annual report - 2008-9

20082009annual reportCOALTECHresearch association

COALTECHRESEARCH

ASSOCIATION

http://www.coaltech.co.za

Coaltech Research Association 3

contentschairman’s review .................................................................................... 4

coaltech structure .................................................................................... 5

steering committees ................................................................................ 6

a celebration of 10 years ......................................................................... 8

research highlights ................................................................................. 12

fi nancial statements ............................................................................... 57

coaltech annual report2008/2009

4 Coaltech Research Association

The years 2008 and 2009 was characterised by economic turmoil. While the beginning of the year was marred by the electricity crisis in South Africa, the commodity boom was still in full swing during April

2008. The price of export coal had risen to record levels and in South Africa the demand for coal was also at unprecedented levels as Eskom was acquir-ing additional coal to rebuild stockpiles.

From October 2008 the situation changed dramatically. Due to the global economic downturn, the demand for electricity – and consequently Eskom’s coal consumption – decreased significantly. At the same time the price of export coal decreased to pre-2008 levels.

Despite the downturn, the support for the Coaltech Research Association remained strong and three additional Associate Members joined Coaltech during this period.

At the beginning of the year it became clear that the South African coal mining industry needed to confront a number of challenges if it was to remain economically sustainable and retain its social licence to operate. These challenges included increased resistance to coal mining from environmental civil society, an escalating water scarcity, global climate change, constrained coal transport capacity, a diminish-ing resource in Mpumalanga and the need to open up a new coal field in the Waterberg.

Consequently Coaltech developed a strategy to address these challenges during the next five years. The strat-egy includes a focus on the waterless beneficiation of coal, improving the utilisation of coal resources, environ-mental conservation and rehabilitation, infrastructure development, the development of the Waterberg coalfield and clean coal technology. In addition, energy efficiency was to be an aspect of all projects.

In accordance with the strategy, Coaltech – while continuing with projects in progress – also embarked upon a number of new projects concerning dry dense medium separation and dry screening of coal, more efficient water treatment technologies, the mitigation of spontaneous combustion, the improved utilisation of rehabilitated mine land and coal transport.

The year under review is also significant in that Coaltech completed its first ten years of operation on 31 March 2009. During the ten years the Coaltech model – in which personnel from all levels in the coal mining in-dustry are involved in the selection and guidance of projects – proved its efficacy and resilience. This model also mitigates the issue of technology transfer, which remains a challenge for some other research undertakings.

In conclusion I wish to thank the members of the Coaltech Board for their support and guidance during a chal-lenging period. In addition I wish to express appreciation to the representatives from the universities of Pretoria and the Witwatersrand, the National Union of Mineworkers and the Department of Minerals and Energy, all of whom contributed their expertise and time to assist the Board.

I also wish to pay tribute to the members of the Steering Committees for their unstinting support and contribu-tions in guiding the work of Coaltech.

Finally I wish to convey the gratitude of the Board to the manager of Coaltech, Johann Beukes, and his ad-ministrator, Carmen Bergman-Ally. Their dedication and perseverance played an immense role in the successes achieved by Coaltech during the year.

Dick Kruger, Chairman: Coaltech Research Association

chairman’s review


coaltech structure

directorsDick Kruger, Chamber of Mines – ChairmanGerhard Jonck, Exxaro – Vice-chairmanJohann Beukes – Company SecretaryWilliam Osae, ARM CoalStan Pillay, Anglo CoalStefan Venter, XstrataVic Cogho, OptimumGerhard Smith, CSIRNoddy McGeorge, BHP BillitonSchalk van Wyk, Sasol

by invitationFrans Knox – BHP BillitonThabo Dube – Department of Minerals & EnergyHuw Philips, University pf the WitwatersrandBrian Roberts, Total CoalJohan Dempers, EskomRonnie Webber-Youngman, University of PretoriaEphraim Malahlela, National Union of MineworkersDavid Nkuna, National Union of Mineworkers

geology &geophysics

coalprocessing

surfaceenvironment

human &social

aspectsengineering

undergroundmining

surfacemining

steering committees

coaltech board

coaltech board


steering committees

geology & geophysicsMarius Smith, Xstrata Coal – ChairmanJohan Dempers, EskomClaris Dreyer, ExxaroMichael van Schoor, CSIRPat Eriksson, University of PretoriaLeon Pienaar, BHP BillitonGeorge Henry, CSIRJohn Ndwamise, Anglo CoalIwan de Jongh, XstrataBruce Cairncross, University of JohannesburgLesley Jeffrey, CIC EnergyRiaan Joubert, Total CoalStoffel Fourie, CSIRViren Deonarain, SasolSimon Mokitimi, BHP BillitonJannie Marais, BHP BillitonFrans Schutte, ExxaroChris van Alpen, EskomGustav Trichardt, Elementary Energy

underground miningNeels Joubert – BHP Billiton – ChairmanBrian Roberts, Total CoalNeels Joubert, SasolDave Roberts, CSIRNielen van der Merwe, CIC EnergyJasper Coetzee, SasolChristian Teffo, Chamber of MinesWellington Chirigo, Kangra CoalStan Pillay, Anglo AmericanJohn Flannigan, BHP BillitonSteve Roos, ExxaroAndre Dougall, SRKRonnie van Eeden, EskomRonnie Webber-Youngman, Pretoria UniversityKalello Chabedi, Wits University

surface miningHenk Lodewijks, Anglo Coal – ChairmanStefan Adamski, ExxaroConri Moolman, BHP BillitonNielen van der Merwe, Bon TerraHuw Philips, University of the WitwatersrandFatima Ferraz, Anglo AmericanDean Hoare, BHP BillitonCezar Uludag, Anglo AmericanKalello Chabedi, WitsBarry Bezuidenhout, BHP BillitonAndy Johnson, SekokoDerek Anthony, AELAndre Pienaar, AELWilliam van der Walt, BME

engineeringErtjies Ernst, BHP Billiton – ChairmanMark Acutt, Anglo CoalRonnie Anderson, EskomEric Croeser, ExxaroPieter van der Walt, SasolJasper Coetzee, SasolFritz van Eeden, Kangra CoalAnthony Coutinho, Department of Minerals & EnergyMartin Gibson, SasolBuks Loock, XstrataJeroen Maaren, MechaneerNelson Pillay, ExxaroFerdie Smith, ExxaroJohn Page, BHP Billiton


coal processing

David Power, Anglo American – ChairmanKobie Badenhorst, Total CoalJohan de Korte, CSIRJakes Jacobs, XstrataSetobane Mangena, SasolThulani Ndlovo, SasolThabo Rabotho, EskomPieter van Heerden, BHP BillitonMark Whitter, EyesizweMientjie van der Vyver, ExxaroDave Tudor, Anglo AmericanJohannes van Heerden, SasolNielen van der Merwe, CIS EnergyMichael Moys, Wits UniversityLydia van der Merwe, Total CoalRosemary Falcon, Fossil FuelAndy Johnson, SekokoGustav Trichard, Elementary Enery

human & social aspects

Dick Kruger, Chamber of Mines – ChairmanEphraim Malahlela, National Union of Mine-workersMaphefo Makgamatha, Mpumalanga Local GovernmentSarel Lessing, XstrataRiaan de Villiers, ExxaroSarel Booyens, SasolClarens Esau, EskomDavid Nkuna, National Union of Mine WorkersLester Peter, EskomMavis Ann Hermanus, Wits

Thandi Mokotedi, Mpumalanga Provincial GovernmentThemba Mataka, Mpumalanga Provincial GovernmentElize Strydom, Chamber of MinesNikisi Lesufi, Chamber of MinesJulie Stacey, WitsAnnelie Naude, Wits UniversityTsheko Ratsheko, Exxaro

surface environment

Dirk Hanekom, EskomLeslie Petrik, University of the Western CapePeter Gunther, Anglo CoalSharon Clark, BHP BillitonNico Dooge, XstrataNielen van der Merwe, CIC EnergyBertie Botha, SasolKevin Kirkman, KwaZulu-Natal UniversityNorman Rethman, Pretoria UniversitySolly Motaung, CSIRLucas Nengovhela, OptimumPiet Wessels, XstrataWayne Truter, Pretoria UniversityCharles Linstrom, ExxaroHallam Payne, UKZNWilliam Pulles, Golder AssociatesJo Burgess, WRCMelanie Naidoo-Vermaak, EskomRalph Heath, Golder AssociatesNikisi Lesufi, Chamber of MinesAndy Johnson, SekokoGustav le Roux, Anglo Coal


The Coaltech Research Association was established in 1999 as the Coaltech 2020 Research Pro-gramme, a collaborative initiative with the vision to develop technology and apply research findings to enable the South African coal industry to remain competitive, sustainable and safe well into the

21st century.Initially its focus was on extending the useful life of coal mining in the Witbank/Highveld coalfield, while

sustaining employment opportunities and utilising the available infrastructure to the year 2020 and be-yond.

Since then the programme has, over a period of 10 years, made the switch from association to a Section 21 company, re-located its premises and extended its research beyond the Highveld to include more than 100 successful research projects (either completed or still ongoing).

in the beginningIt all started in 1997 when the mining technology division (Miningtek) of the Council of Scientific and In-

dustrial Research (CSIR), the University of the Witwatersrand (Wits) and the University of Pretoria (UP) set up a cooperative research programme for four gold mines. Known as Deepmine, the programme’s goal was to do research on mining conducted between 3 000m and 5 000 m underground.

a celebration of 10 years


The model was so successful that the three partners decided to investigate the possibility of setting up such a model for the coal industry.

The original objective was to establish a sustainable forefront technology and human resource base to im-prove the overall productivity and reduce the costs incurred by South African coal mines, in order for them to be and stay internationally competitive. To achieve this, Coaltech 2020 had five goals:

- to develop a new coal mining research programme,- to increase the human resource capacity for research and development,- to establish a culture of innovation,- to encourage rapid technology transfer and implementation, and - to extend the useful life of existing mining operations and other infrastructure.

Getting startedExperts from industry, the state

(through the Department of Minerals and Energy – DME) and labour (the Na-tional Union of Mineworkers - NUM) – and across a broad spectrum of tech-nical disciplines – invested considera-ble time and energy to develop the final programme.

In April 1998 a Coaltech 2020 Steer-ing Committee was formed under the chairmanship of a senior industry exec-utive to guide the planning process. In that year alone, 10 Steering Committee meetings were held.

A one day workshop was also held at Eskom with nearly 50 participants. The workshop focuses on a wide spectrum of problems facing the coal industry in this country. The organisa-tions involved were Amcoal, Chamber of Mines, CSIR, DME, Duiker, Eskom, NRF/THRIP, Ingwe, Iscor, NUM, Wits and Pretoria University.

The workshop also grouped the research needs into seven technology projects and 95 new research top-ics or needs were identified. It developed the Coaltech 2020 Programme Framework which was then refined at various subsequent meetings and workshops.

Seven separate technology projects were initially identified. The technology project on Saleable Product was subsequently combined into Coal Processing and this project was renamed Coal Processing and Dis-tribution.

The six final technology projects included: - Geology and geophysics- Underground mining- Surface mining- Coal processing - Coal distribution- Surface environment mining - Human and social aspects However, it was recognised by the steering committee that further workshops were needed to determine

the objectives, outputs, milestones, cost and duration of each research task identified. The second series of technology project workshops were then carried out at the CSIR Miningtek between

27 August and 3 September 1998. A total of 87 coal industry experts from mines, mining groups, labour


unions, the DME, universities and research agencies participated and nearly 850 man hours were spent at the workshops in generating the outputs detailed in this document.

The result was the formulation of a comprehensive research programme, consisting of 90 research tasks. At the beginning of November 1998 the Coaltech 2020 business plan was prepared. It was presented to the various coal mining houses and stakeholders at the end of November 1998 with the final decision to estab-lish the research programme made in December of that year.

On 1 April 1999 the programme officially came into being. It represented the culmination of 12 months of planning and work by the steering committees, industry representatives and other interested parties. Impor-tant to note is that its establishment was a milestone in coal mining research in this country.

human resources and students There are two requirements for the Coaltech 2020 programme to be a success: the technical problems

must be solved by research and the coal mines must become more receptive to the results of research. To achieve both these objectives implies much more postgraduate research that focus on those areas that make up the Coaltech programme.

From 1999 to 2008, 59 degrees were completed. This included 12 PhDs and 27 Masters degrees, of which 11 were awarded to previously disadvantaged individuals and 19 to women

a change In 2007 Coaltech 2020 underwent some changes. It became a research association incorporated under

Section 21 of the Companies Act, 1973. It also relocated to the Chamber of Mines building. Its programme manager, Johan Beukes, moved with the programme.

Today the Coaltech Shareholders are: Anglo Coal, Xstrata Coal, Eskom, Exxaro Coal, Sasol Mining, BHP Billiton Energy Coal South Africa, Total Coal, the CSIR, the Chamber of Mines, Bon Terra Mining, Kuyasa Mining, Kangra Mining, Leeuw Mining with Wits, UP, NRF, labour (NUM) and the DME.

The programme has gone from strength to strength since this change, with big established coal compa-


nies renewing their membership or coming on board. The programme also created a class of associates for smaller companies interested in particular aspects of Coaltech 2020’s research, but not in all areas. The companies are able to join the research areas relevant to them within Coaltech 2020. In this way the pro-gramme has seen a plethora of companies joining.

celebrating 10 yearsDuring the past 10 years, the programme has completed more that 100 research projects. The Coaltech stakeholders have benefited from the leverage generated by pooling resources and from the

experiences that collaborative research can harness. The value of Coaltech is that competing companies are able to sit around a table and share information.

There are five factors which make this research programme unique to the coal mining industry: It is truly collaborative: collaborative between mining houses and Eskom, labour, and the state, as well as collaborative between the universities and the various research and funding organisations;It is driven by industry needs;It provides for a formal involvement of students and partnerships with centres of tertiary education;The proposed funding arrangement requires industry to contribute a third of the funds needed, while the balance is funded by various state organisations.It involves a voluntary tripartite partnership between business, the state and labour.

The Coal mining industry has shown that companies competing with each other can work together in knowledge development. Coaltech 2020 has evolved over the past 10 years and shown that it is adaptable. Its chairperson, Dick Kruger, is confident it will continue for another decade.

‘The strength of Coaltech 2020 is that the people using the knowledge are the people who oversee its de-velopment. The thrusts are drawn from mine personnel. They define the problem and work closely with the researcher and supervise them. As a result, knowledge transfer has never been a problem. It has resulted in a sense of ownership by the coal companies from the top to the bottom levels.’

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research highlights

introduction

The Waterberg Coalfield (Figure 1) in the Limpopo Province contains vast resources of coal and is the next area that will supply South Africa with energy well into the future. The coalfield is in the Karoo-age Ellisras Basin. Coaltech Research Association commissioned an airborne geophysical survey

of the area (Figure 2), to better understand the structure of the basin. Methods applied were the magnetic method and the radiometric method. The datasets collected were:

• Magnetics (Figure 3)• Total count radiometrics (Figure 4)• Uranium count radiometrics (Figure 5)• Thorium count radiometric (Figure 6)• Potassium count radiometrics (Figure 7), and• Digital Elevation Model (DTM) (Figure 8)

The magnetic susceptibility in the Ellisras Basin is low; however, the application of a phase operator on this data (Figure 9) re-veals a large amount of weakly magnetised anomalies that could be due to pre-Karoo features in the basin floor. The radiometric data complemented the magnetic data by delineating the basin boundaries and indi-cated large block faulting.

importance of the studyThere is currently only one mine in the

Waterberg Coalfield (GrooteGeluk) and is the sole supplier to Matimba Power Station. Medupi Power Station – which is of similar size – is currently under construction in the same area and will also source its coal from Grootegeluk, which may cause delivery ca-pacity problems.

The Waterberg Coalfield is highly faulted and all the structures and their effects have not been identified and studied to date. Pre-cise locations of the faults and structures

geology & geophysicswaterberg coalfield airborne geophysics


will greatly impact on the estimation of both the shallow and deep coal resources, by removing some of the uncertainty regarding the coal resources.

geological settingThe coal-bearing rocks belong to the Karoo Supergroup and was deposited between 260 and 190Ma ago.

It formed as a large graben structure bounded by basin edge faults:

In the north, on older basin rocks (Melinda Fault zone) that belong to the Limpopo Mobile belt.In the south, with the Waterberg Group (Eenzaamheid and Ellisras Faults).Post Karoo faults (Daarby Fault) that disrupt coal seams.The formation of the basin was controlled by structures that were formed and reactivated over time (Daar-by Fault) and is the basis for the block faulting that occur throughout the basin.

stratigraphyThe area covered by the geophysical investigation consists mainly of three types of geological terrains:

The Limpopo Mobile Belt – highly metamorphosed gneiss which is 2700Ma (Kramer et.al, 2006).The Ellisras Basin – consisting of the Waterberg Group (Barker et. al, 2006) and the Karoo Supergroup (Johnson et. al, 2006b) – contains the coal, of which most is in the Grootegeluk Formation (110m thick in the south).Recent cover is from the weathering of gneiss of the Limpopo Mobile Belt, the Karoo rock in the north and from Waterberg sandstone in the south.Intrusive rocks – the most important of these rocks are those that cut through the coal-bearing rocks and disrupt the seams. They occur less frequently in the Ellisras Basin.

geophysical surveyThe survey was conducted in 2007 and covered eight 1:50 000 sheets. The survey was flown in a N-S

direction at a 200m line spacing. The flying height was 80m at a speed of 230km/h. The sampling frequency was 10Hz, which implies a measurement every 6.5m. The magnetic data was collected with a caesium va-pour magnetometer (resolution 100pT). The radiometric data was collected with 80 litre NaI crystal and the

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elevation was measured using a laser altimeter.The contact between the Limpopo Mobile belt and the Ellisras Basin can easily be seen on the magnetic

data (Figure 3). It also shows the absence of strongly magnetised structures in the basin.The total count radiometric data (Figure 4) shows the northern contact of the Ellisras Basin clearly and the

large block faulting. It also shows radioactive material eroding from the source (Waterberg sandstones) in the south into the sediment load of the north-flowing Mokolo River. These sandstones are mainly the Feld-spar-enriched Kranskop Sandstones, which indicate that the original source was granitic in composition. The source in the north is the gneiss of the Limpopo Mobile Belt.

The uranium count (Figure 5) and the thorium count (Figure 6) show a similar pattern. The higher thorium count suggests that the source of the radioactivity is much older; i.e. the current source is a second genera-tion source.

The potassium count (Figure 7) is the highest and maps the distribution of the radioactive isotope of feld-spar.

geophysical interpretation

figure 7: waterberg potassium data figure 8: waterberg dtm data

figure 4: waterberg total count data

figure 5: waterberg uranium data figure 6: waterberg thorium data

figure 3: waterberg magnetic data


The enhanced phasemag data (Figure 9) show all the smaller anomalies in the magnetic data. This con-firms the idea that the structure in the Ellisras Basin is either weakly magnetic, or all structure is below the Karoo cover in the basement material (Waterberg).

Fieldwork indicated that dyke outcrops are scarce and highly weathered. The complete dataset was used to do a lineament interpretation (Figure 10). All interpreted dykes and faults were indicated.

A surface geology interpretation was done by using a ternary radiometric image (Figure 11). It was calcu-lated by using potassium count in the ‘red channel’, total count in the ‘green channel’ and uranium count in the ‘blue channel’. The interpreted surface geology is shown in Figure 12. The major interpreted block faulting is shown in figure 13.

figure 9: phasemag data figure 10: lineament interpretation

figure 11: ternary image of the waterberg coalfield figure 12: surface geology interpretation

figure 13: interpreted block entities


physical propertiesTo do a credible geophysical interpretation and modelling, it is always necessary to sample the geology and

measure the physical properties of the different lithologies. Samples were taken of the Karoo Lavas (Letaba Ba-salt), Karoo sandstones (Molteno Formation) and Waterberg sandstones (Kranskop, Holkrans and Mogolakwena formations) (Figure 14).

A specimen was taken from what we first believed was a hyrdrothermal or felsitic dyke (Figure 15). Microscope studies showed that it is an iron rich pisolite with growth rings around a quartz nucleus. This means that origin was not hydrothermal, but hygroscopic.

The physical properties show that the basalts and shales are magnetic and conductive. The sandstones are mostly non-magnetic. Densities of the shales and sandstones vary.

Using this data, profiles were modelled that indicated that the Waterberg is a half-graben structure (Figure 16).

conclusionsThe airborne geophysical survey was a major contribution towards the knowledge of the Ellisras Basin. The

data and the first interpretation have shown that the basin has undergone much more structural disturbance than what was previously suspected. The survey also showed a large amount of previously unknown structure in the basin.

This poses the question; how many of these structures remain undetected because they are non-magnetic in

nature? The question can most likely be satisfactorily answered by an airborne electromagnetic survey. It will produce much more additional data that will help us understand the structure of the Ellisras Basin better. This will ensure better coal delineation and ultimately better mining practises with a better coal recovery.

figure 14: geology formations of the waterberg coalfield figure 15: pisolite structure discovered in the waterberg coalfield

figure 16: model of the waterberg basin


compilation of a textbook: a guide for using geophysics on the south african coal fields

This project aims to produce a comprehensive guide for coal geologists on the principles, application, strengths, weaknesses and pitfalls of all geophysical techniques that have been used, or might be applicable on the South African coal fields.

The book will cover the following topics:

Introduction to South African coal mining and exploration;The physical properties of coal: a discussion of the petrographic composition of coal and surrounding rock types and how this relates to physical properties;Introduction to the geophysical techniques applicable to coal, including magnetics, gravity, electromag-netics, electrical methods, borehole methods, airborne geophysics, seismics, wireline logging and satellite imagery;Description of different techniques and the underlying principles;Overview of the application of geophysics to coal internationally: a historic overview and recent develop-ments;Summary of coal problems and possible geophysics solutions – problem scenarios to be discussed in-clude cavity/old workings detection, depth of weathering detection, dyke and sill detection, pollution plume mapping, dolomitic pinnacle mapping, coal thickness left in floor/roof of mines, mapping coal underneath pans, coal quality, geotechnical analysis of boreholes, SPONCOM and underground fires;Potential future technologies, including in-seam radar, roof profiler, ERT streamer for wetlands coal map-ping, chirp for wetlands coal mapping and acoustics for seam thickness mapping.

The book will also include a collation of existing physical properties and information on useful resources; for example, a listing of geophysical service providers and internet resources.

The publication of this book is expected to have a number of key impacts in the areas of safety, health, environment and economy; for example: It will increase the awareness of the role that geophysics could play in characterising hazardous geological anomalies and other subsurface hazards, including near-surface cavities, underground fires, hazardous roof conditions, pollution plumes etc. The successful (and more ef-fective) application of geophysics could contribute to more cost effective mining.

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The recent increase in the demand for thermal coal required by Eskom for electricity generation, has prompted the coal industry to review the technologies and techniques available for processing low grade coals in order to produce thermal coal. In the past, power stations were mostly supplied with

a relatively high-grade of raw coal from a small number of captive mines. Presently, coal is supplied from many different sources by a variety of large and small companies. Some of the coal potentially available for

combustion by Eskom is of a low grade and has to be beneficiated to remove stone, shale and pyrite prior to use.

It is necessary to find new technologies that can be used to remove the contaminants from the raw coal – a process referred to as ‘de-stoning’. A suitable process should be able to handle large tonnages, be inexpen-sive to install and operate and must still be able to de-liver the required quality of coal. In South Africa, water is a scarce resource and the optimal use of water dur-ing coal processing is a further concern that has to be

taken into consideration.Coaltech has embarked on a process to review and

evaluate available technologies for the beneficiation of low-grade raw coals and discards. Current dense-me-dium processes, wet jigging, dry jigging or dry shaking tables as well as optical sorting technologies are be-ing evaluated as part of the process.

Although dry processing is generally less efficient than the conventional wet processing technologies, it does offer several advantages. Firstly, no water is consumed, which is a very important consideration for mining operations in South Africa and in particular for the Waterberg coalfield. Secondly, pollution of streams is eliminated since no slurry is produced. A third important consideration is the fact that the moisture content of the product coal remains low, which ensures that the heat value of the coal is maximized.

Coaltech is therefore looking specifically at the potential of dry beneficiation techniques in the South Af-

coal processing

dry processing of coal

figure 1: sorter at mintek

figure 2: FGX in operation at NBC


rican context. Three potential dry-processing technolo-gies are available, namely optical sorting, dry jigging and dry dense-medium beneficiation. Optical sorting tests are being conducted in co-operation with Mintek, whilst dry air jigging is being evaluated in cooperation with both Exxaro and Xantium. At present, tests are be-ing conducted on pilot-scale FGX air-table units capa-ble of processing 10 tons of raw coal per hour. Xantium is busy with the construction of a full-scale FGX plant and testing will also be done on this plant in the near fu-ture. The optical sorting machine at Mintek is shown in Figure 1. Figure 2 shows the Exxaro pilot FGX air table is in operation at NBC Mine near Belfast. The Xantium test unit, in operation at Palesa Mine, is shown in Figure 3.

dry screening of coalDuring the dry beneficiation of coal, it is usually required to pre-screen the raw coal at a relatively small

screen aperture, typically 6 mm, in order to remove the finer coal prior to beneficiation of the coarse coal. It is also viable in many cases to remove the -6 mm coal from the feed coal to a dense-medium or wet-jigging plant. Keeping the fine coal dry, maximizes the heat value of the coal and improves the efficiency of the op-eration.

It is thus required to dry-screen raw coal that is not always completely dry. Dry screening of coal at small screen aperture sizes is very problematic when the coal contains more than about 5% moisture. This is often the case in practice, since water is routinely used dur-ing mining operations to control dust emissions. During rainy weather, the problem becomes worse.

Tests conducted with a pilot-scale Bivi-TEC screen, as well as on a full-scale screen in production at New Clydesdale Colliery, have thus far given encouraging results, but further research is still required. The Bivi-TEC screen in operation at New Clydesdale is shown in Figure 4.

dry dense medium separationA technology that is new to South Africa (but report-

edly already in limited commercial use in China), is dry fluidised-bed dense-medium separation. This process offers all the advantages of dry processing plus good separation efficiencies.

A preliminary Coaltech sponsored study into dry dense-medium separation at the University of Kwa-Zulu Natal (UKZN), yielded encouraging results and the study has now been expanded to include the University of the Witwatersrand. The laboratory-scale dry dense medium separator constructed at UKZN is shown in Figure 5.

figure 4: Bivi-TEC screen at New Clydesdale Colliery

figure 3: FGX in operation at Palesa Mine

figure 5: Laboratory scale dry dense medium drum


This task has been at the very forefront of Coaltech’s Engineering steering committee’s activities since 2004. Very little has – deliberately – been published in the public domain. The time has come to change this. A little background information on the considerations leading up to the establishment of this project is probably in order first.

South African coal demand is soaring, with an increasing need to extract coal under worsening min-ing conditions from dwindling fossil fuel reserves. Although national estimates vary significantly, the minimum percentage of unminable coal reserves is estimated at more than 20%. There are many

reasons why perfectly combustible coal is not mined, chief of which are stone boulders buried within the seam (called ‘floating stone’), layers of various thickness stone sheet (called ‘lenses’) or because the floor or roof – or both – pinch off access to coal behind them over such a distance as to make it uneconomical to mine through. These stone formations easily damage highly productive mechanised mining machinery that is specifically designed to deal with coal. Even at a very conservative national reserve estimate of only 30 billion tons of minable coal, there is a significant amount of coal (i.e. 6 billion tons or more) that can be liberated if the associated stone can be effectively mined through.

Coaltech’s engineering steering committee’s chief goal is to develop effective measures to reduce the overall capital cost of mining per ton of coal removed. One way would be to directly influence the cost of equipment ownership and another is to increase the yield from existing infrastructure and resources by liber-ating more useable coal for the same cost expenditure. The current Vibrant Roadheader project is squarely aimed at both these approaches.

There is also an opportunity around national priorities – such as new job creation and poverty alleviation – by helping smaller mining groups (of which many are BEE partners) in their choice of potential low cost, high value mining equipment suitable for replacing drill and blast coal mining operations, and by stimulating entrepreneurial activities such as local after sales support system creation.

In South African coal mining the unfortunate situation has developed where very expensive mining equip-ment has to be used in applications they were not designed for. Currently there is no rock cutting technology that can compete in terms of reliability with drill and blast stone work mining. Drill and blast mining often damage the stability of the rock strata, which increases the cost of support and safe mining.

The advent of a vibration technology cutting head could just change this situation. The vibration technol-ogy superimposes a high frequency impact motion on top of the normal rotational motion of a cutting pick, much in the same way as impact is used when drilling with a masonry drill bit into concrete. And because the Chinese machinery is so competitively priced, it makes them extremely attractive and deserving of seri-ous consideration.

In 2005/6, Coaltech tested the first vibration technology roadheader (ELMB-75C) in a South African coal mine, with limited success. The primary objective of the test was to determine the ability of the vibration technology to improve the cutting ability of the cutting head in various stone formations. The primary limita-tion identified was that the vibration technology cutting forces could not be made to bear upon the targeted

engineering

the search for a more cost-effective stone cutting machine


rock types due to insufficient stiffness provided by the roadheader embodiment. As a result, it could not be determined if the fundamentals of the vibration technology were sound. After much deliberation and lobby-ing for funding, Coaltech members decided to order a much heavier and stiffer embodiment to re-test the vibration technology cutting head.

After significant

flame proof modification and the

adaptation to accept both the 75 kW and 120 kW cutting booms

at a leading coal mine workshop, the new Vibrant Roadheader machine

was delivered to a South African coal mine for

follow-on testing in March 2009. The original objective – evaluation of the vibration technology – has been expanded to include the testing of a more powerful non-vibrating cutting head in the same stone work conditions, to get some idea as to what the base potential might be should a much more powerful cutting head also be activated or vibrated (the latest news from China is that a 132 kW vibrating head has just been unveiled). Apart from these considerations, the tests now also include operational cost and production data, where possible.

The new machine is based on a standard 120 kW roadheader from China, which doubles the mass of the frame attached to the vibration technology cutting head and boom. Significant changes were also made to the hydraulic circuit, which, combined with the larger, heavier embodiment, also helps with the stiffness.

The second vibrating head cutting test has just ended and the detailed data analysis has only just begun. Although it is too early to publish any conclusive results yet, a great deal was learned.

The new machine was first tested on a remnant full coal face section, where the operators could learn to master the machine with little risk of damaging it. Further, since the machine had to be reassembled with very little assembly documentation, any start-up problems could be addressed too.

After cutting in coal for three weeks, the machined moved to a new face where 30% of the face consisted of a 70 to 80 MPa siltstone formation at the floor parting.

After a short period of operation it became evident that the fitment of a vibrating cutting head to a body not originally designed for vibration, caused all kinds of problems, like bolts and other fittings vibrating loose, causing significant delays. Through dogged determination and perpetual vigilance over an extended period of time, these vibration related failures were systematically rectified, until the machine’s reliability improved to such an extent that meaningful testing could commence.

Testing procedures and methodology had to be changed and tweaked continuously, but in the end enough data was collected to be able to compare the vibrating versus non-vibrating mode performance of the 75 kW cutting head with respect to advance rates. Long term phenomenon, such as the effect of vibration on a possible increase in tonnes mined per pick, could not be determined, though results obtained seem to

figure 1: The new EBZ-120MN Roadheader fitted with the ELMB-75C cutting boom


point in this direction.

During the trial it became apparent that, although the mass of the machine was increased by almost 100%,

it was still not enough and that the bearable cutting force was also insufficient. Both these factors made it

impossible to fully engage the cutting head into the stone, and the maximum cutting loading achieved was

less than 50% of the available power (for both the 75 kW and 120 kW heads). By changing the testing meth-

od and by increasing the hydraulic pressure by 40% during the latter part of the 120 kW cutting head trial

phase, results were obtained that confirmed the potential of the machine. The 120 kW non-vibrating cutting

head consequently yielded surprisingly good increases in advance rates, which surpassed the performance

observed from the 75 kW cutting head. Time constraints prevented further testing of the 75 kW cutting head

with this increase in supply pressure, though comparable increases in performance can be expected.

During the trial the opportunity presented itself to thermally analyse the cutting operations and gather a

figure 2: the coal test-face figure 3: the first stone face, 30 % stone (near floor)

figure 4: a large floating stone on the first panel, with another view for scale

figure 5: the second stone face, dissected by two very hard sand stone lenses (one shown right)


whole new set of data. Of primary interest were the thermal images identifying maximum spark temperatures

while cutting sandstone in the roof. Perhaps surprisingly, a preliminary review of the captured data suggests

that thermal temperatures are not nearly as high as the brightness of some sparks might seem to suggest.

For the last two weeks of the trial, a third 70/30 stone face (the majority siltstone – again dissected by two

very hard sandstone lenses) was used for testing the 120 kW cutting head. During this period there wasn’t

a single stoppage due to the unreliability of the machine. This is a testament to the dedication, commitment

and resourcefulness of the support personnel in bringing the machine to this point of reliability and to the

base potential of this specific embodiment.

The detailed draft trial report should be ready for comment by the engineering steering committee by early

September 2009. After the trial report has been finalised, the engineering steering committee will make a

recommendation to the Coaltech board on the way forward.

figure 6: minor body modification and repair work (spinner drive motor came loose 3 times)

figure 7: a view of the 75 kW cutting head in action Figure 8: a thermal image of the picks directly after cutting sandstone in the roof

figure 9: the largest piece of slab-stone conveyed through the machine – 5 x 0.45 x 0.12 m


surface environment

brine treatment and disposalintroduction

T he aim of this Coaltech funded research is to develop a methodology/technology in which coal mine waters and brines can be pre-treated, beneficiated or concentrated.

There are three components to this project. Firstly, the screening of coal mine waters and brines for their concentration profile, pH, speciation, cation and anion balance, absorption capacity and equilibrium analysis. Secondly, an investigation of the removal of the minor and trace elements such that the waste water stream is simplified to ensure more effective downstream progressing (UWC). The third part of the project looks at further downstream processing where the removal of the major elements from the processed waste stream is considered. This part is further divided into two sections – the Eutectic Freeze Crystallization (UCT) technologies and the use of counter current ion exchange (CPUT). The approaches to achieve these objec-tives have been as follows:

1. Screening of coal mine waters and brines (UWC)Screening of brines for their concentration profile, pH, speciation, cation and anion balance, absorp-tion capacity and equilibrium analysis

2. Problem element removal from brines (UWC)Optimisation of the synthesis condition of zeolite Na-P1 from Arnot flyDetermination of Cation Exchange Capacity (CEC) and % toxic element removal from brine with zeolite Na-P1 Removal of sulphate from circumneutral mine water Adsorption of toxic elements from brine with natural clays and zeolitesThe synthesis of immobilised crown ether ligands for selective removal of Cr and other toxic species from brine effluentsThe synthesis of highly selective mesoporous sorbents for mercury removalFunctionalized Polyacrylonitrile (PAN) fibres containing amidoxime groups for metal ion adsorption from brineElectrodeionization for removal of major and trace elements from brine

3. Removal of the major elements Eutectic Freeze Crystallization (UCT)Sequential removal of pure salts operating under eutectic freeze crystallization conditions and within the metastable zone widthIon Exchange Treatment (CPUT)B.Tech mini projectsCounter current ion exchange (CCIX) and membrane processes for recovery of major elements from brine

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1. screening of coal mine waters and brinesThe evolution of brine water streams during industrial processing, at Tutuka Power Station and Secunda

industrial complex for instance, was investigated as an example in order to understand the variability in process brines, as well as what effect each stage in the industrial process might have upon the brine water quality. The sequence of the brine evolution during water treatment stages at Tutuka Power Station is shown in Figure 1. Figure 2 shows the composition of brine at each stage in the process in comparison to the intake water feed where cooling and mine waters are mixed.

figure 1: sequence of the water treatment stages at Tutuka Power Station.

legend for figure 1TP108 cooling water: mine water mixture at clarifier outlet (ca. 1:9)

TP208 mine water (New Denmark)

TP308 cooling water/mine water mixture (after microfiltration, acidifying and chlorine addition)

TP408 RO Brine

TP508 RO Permeate

TP608 brine after contact with ash

TP708 cooling water

TP808 feed for vapour compressor (combined RO brine)

TP908 vapour compressor reject (VC brine)

TP1008 vapour compressor product

figure 2: composition (% difference) of brine at each stage in the process in comparison to the intake water feed where cooling and mine waters are mixed.


The samples taken from the different water treatment stages at Tutuka Power Station have similar chemi-cal compositions because the water is evolving from one source (mixed mine water and process cooling water). The difference in quality is in the concentration, namely the amount of ions, as they are added into a stream (or removed) by the desalination processes. Mine water and the vapour compressor condensate showed differences in composition from the general trends. Desalination by reverse osmosis and vapour compression removes cations and anions to a large extent, except Si, Cr, Mn, Fe and Pb. The Na content in the vapour compression reject brine increased by 2237.1%, Mg by 1894.4% and Ca by 1930% in relation to the starting water (TP108 - mine water mixture at the clarifier outlet).

Samples from Sasol Synfuels Complex in Secunda generally had similar compositions The RO brine from Sasol-Secunda is more concentrated than that from Tutuka Power Station, but brines from both sites can be classified as a Na-SO4 water type. Analysis of Piper diagrams showed all the data points lay in a single line, meaning that the samples are mixtures of one another. This follows from the fact that effluents are recycled at these sites.

PHREEQC, Aq.QA and Visual MINTEQ speciation models were used to calculate the saturation indices of discharge streams from desalination activities at Tutuka Power Station and Sasol Synfuels Complex in Se-cunda. The saturation indices of all the minerals predicted were found to be between -10 and 25, except for results obtained from non-converging calculations of four samples from Sasol Synfuels Complex (modelled using PHREEQC). The calcium concentration was much higher in some brine samples which had been in contact with fly ash at Secunda. These samples had convergence problems during modelling with PHREE-QC. The program fails when non-carbonate alkalinity is greater than the specified total alkalinity as the program tries to calculate total carbonate species such that carbonate alkalinity + non-carbonate alkalinity = total alkalinity. The study findings show that saturation indices for calcite and aragonite (from converging calculations) done using Aq.QA and PHREEQC models were comparable.

Middelburg mine waters – as well as many other mine waters – are rich in calcium and magnesium concen-trations and the pH of these waters is near to neutral. Fluid properties obtained using the Rockware Aq.QA software shows that Middleburg and Navigation mine waters are of Mg-SO4

2- and Fe-SO42- types respec-

tively. The sulphate concentration in these waters varies between 4500 ppm to 5000 ppm.Modelling showed that most brine streams, including mine water, were likely to precipitate minerals such

as calcite and aragonite because of the brines being supersaturated with respect to these mineral phases. This leads to scale build up in facility piping and equipment used to handle these water streams.

2. problem element removal from brines

The synthesis of pure phase zeolite Na-P1 product from flyash was optimised by using a factorial designed

study of the many synthesis variables. Zeolite NaP1 was successfully prepared from Hendrina and Duvha

fly ash after the ideal conditions for synthesis – when using Arnot fly ash – were identified and applied. The

purest phase zeolite Na-P1was obtained from Arnot fly ash when ageing was performed at 47 °C for 48

hours and the optimum water content was at a molar ratio of 1 SiO2 ; 0.42 Al2O3 ; 0.06 NaOH ; 0.49 H2O in

the hydrothermal step, while optimum crystallisation occurred at 140 °C after 48 hours. A small pore zeolite,

hydroxysodalite was produced when using brine – instead of pure water – as a solvent in the hydrothermal

synthesis process together with Arnot, Hendrina and Duhva ash.

The Cation Exchange Capacity (CEC) of the zeolite product improved to more than 4 meq/g by optimisa-

tion during synthesis, when changes were made to the the ageing conditions and the water content used

(Figure 3).

Larger quantities of toxic elements could be removed from Emahlahleni brines when a zeolite NaP1 prod-

uct was prepared using fly ash (FA) (Figure 4). Removing toxic elements from Emalahleni brine was most

effective when the optimized zeolite Na-P1 prepared from Arnot fly ash was used, and most of the toxic ele-

ments present in brine (Pb, Cd, Ni, Mn,V, As, B, Fe, Se, Mo, Sr, Ba) were significantly reduced. Moreover, the


zeolites showed a significant reuse capacity and could selectively remove the toxic elements from a highly

complex, high salt brine matrix.

Eskom have committed themselves to fund both the scale-up of the synthesis of zeolite Na-P1 from fly ash

to small (400 ml) pilot scale stirred reactors, and the technoeconomic study of preparing zeolites from ash

at a larger pilot scale.

Experiments were conducted to reduce sulphate levels in circumneutral mine waters – such as mine water

found at Navigation and Middleberg mines – by treating these effluents with fly ash (FA). These waters are

sulphate rich, containing sulphate levels of above 4000 ppm, but are not acidic and is therefore a dilute form

of brine. For instance, Hendrina mine water has very low levels of Mn, Na and K ~30 ppm, Ca ~500 ppm and

850 ppm of Mg but contains high sulphate levels. In our study we successfully treated circumneutral mine

water with FA and removed sulphates to the saturation point of gypsum. Removal was pH dependant and

the maximum pHs attained were 10.13, 11.77, 12.12 and 12.31 for minewater to FA ratios 5:1, 4:1, 3:1 and

2:1 respectively. For a 5:1 ratio of minewater to FA, 54.92% sulphate removal was observed while for 2:1 ra-

tio 71.06% sulphate removal was achieved. At pH > 9, Mn(OH)2 starts to precipitate from the circumneutral

water and was completely removed from the mine water.

Thus, treating mine water with FA to pH 12 results in 70% sulphate removal. Treating mine water with FA

and adding Al(OH)3 resulted in 95% removal of sulphates, while the final concentration of sulphates was 213

ppm, below the DWAF effluent limit of 500 ppm. The optimum amount of Al(OH)3 to be added was 0.0844 g

per 100 ml of mine water. This is a significant finding.

The best sulphate removal was achieved when seeding with gypsum crystals followed by the addition

of Al(OH)3 at high pH, further precipitating out sulphates. Initial results on optimisation show that the proc-

figure 3: cation exchange capacity as a function of water content during preparation of zeolite Na-P1

figure 4: toxic element removal from Emalahleni brine with optimized zeolite Na-P1 prepared from Arnot fly ash


ess can be improved by enhancing the degree of ettringite precipitation as a way to remove the maximum

amount of sulphates.

Circumneutral mine water (CMW), mixed with highly contaminated acid mine drainage (AMD) in different

ratios, could also be treated with fly ash (Table 1) and removal of sulphate to above 90% was achieved after

short contact times, without further addition of any chemicals or seeds or Al(OH)3.

INITIAL concentration FINAL concentration

pH SO42- (ppm) pH SO4

2- (ppm) % removal

AMD 2.4 42862 – – –

CMW 6.5 4623 12.35 1191 74.24

*mixture 1:1 2.56 20870 10.16 1842 91.17

*mixture 2:1 2.65 17142 12.69 1228 92.84

*mixture 3:1 2.63 15797 12.66 1236 92.76

table 1: FA treatment for sulphate removal from CMW blended with AMD

(*CMW to AMD ratio (and the ratio of the mixtures to FA is 2:1)

Trace levels of B, Cr and Mo seeps into the water from the ash treatment to above the required effluent

limit, but B and Mo levels can be reduced in the process water by using zeolites synthesized from FA.

Cr removal is also being investigated. Low cost material – such as fly ash –, natural clays – such as cal-

cium and sodium bentonite clay –, attapulgite clay and natural zeolites – such as clinoptilolite – are being

studied. Clay particles can adsorb anions, cations, non-ionic and polar contaminants from natural water or

contaminated water. Clinoptilolite have CEC values between 100 and 400 meq 100 g−1). Adsorption studies

are in progress.

The selective extraction of Cr6+, As5+, Sr2+, Cd2+, and Hg2+ and U is possible using highly selective crown-

based ligands immobilised on porous SiO2 support surfaces. We have successfully immobilised the 18-

crown-6 on silica-gel (60Å) and the results were confirmed by solid state NMR as well as FT-IR. After the

initial trials of the immobilization, a whole series of immobilized 18-crown-6 were prepared for the extraction

of various toxic elements from water. We are still awaiting results of the % toxic element removal obtained

with these materials.

The mercury (Hg2+) levels in the sampled mine waters have been found to be higher than the DWAF re-

quirement. Therefore, we are investigating the use of high surface area mesoporous silica and their carbon

analogues for highly selective mercury removal. A high surface area carbonaceous material possessing sur-

face oxide groups has been successfully synthesized via a CVD process using a silica template. The surface

properties of these new materials are currently under investigation with model dye molecules and will then

be applied for Hg removal.

The research on Ion Exchange Fibres is ongoing. Advantages of fibres as adsorbents include a relatively

high osmotic stability allowing for multiple drying and moistening of the filaments, as well as an overall in-

crease in surface area which promotes faster particle diffusion. We are confirming the repeatability of the

amoxidime functionalised polyacrylonitrile fibres and also assessing their ability to remove some trace ele-

ments from mine waters in addition to the Ca2+ and Mg2+ already successfully evaluated. Uptake of the alkali

/alkaline earth metals was good and also independent of pH, thus amidoxime functionalised fibres did not

exhibit any preferential affinity for Ca, Mg, Na. The adsorption kinetics were found to be sufficiently rapid

reaching equilibrium in 15 minutes. The advantage of the fibrous configuration of the polymer backbone is


the faster rate of equilibrium compared to resin beads.

Research on electrodeionisation is actively being persued after a research visit by Dr L Petrik to 3 laborato-

ries in Turkey during June 2009 – sponsored by the NRF – which included a visit to Prof Nalan Kabay at Ege

University in Izmir where collaborations in electrodeionisation were finalised. Dr Kabay has vast experience

in functionalised ion exchange fibres. Dr Nuran Boke, a post doctoral fellow from Ege University, has arrived

at UWC and started her year of post doctoral studies with ENS and is recommissioning the electrodeioniza-

tion system at present.

B. eutectic freeze crystallisation

During 2009, the Crystallisation and Precipitation Unit, Department of Chemical Engineering at the Uni-

versity of Cape Town, continued to make significant advances in the novel research area of Eutectic Freeze

Crystallization (EFC) for the treatment of hyper-saline brines. This research, under the guidance of Prof Ali-

son Lewis and Dr Jeetan Nathoo, is at the stage of scale-up from laboratory glass reactors to a 2L stainless

steel reactor – a scraped cool-wall reactor that has been designed to conduct both batch and continuous

experiments. This reactor has been constructed and the commissioning phase is due for completion in June

2009. The coolant Kryo 45 – used as the heat transfer liquid with a temperature range of -45ºC to 30ºC in

place of methanol – has proved successful and will continued to be used. The Ph.D proposal of Mr Dyllon

Randall – ‘Sequential Removal Of Pure Salts Operating Under Eutectic Freeze Crystallization Conditions

And Within The Metastable Zone Width’ – was accepted by the selection committee for an upgrade from an

M.Sc. Mr Randall will be travelling to the Netherlands from June to work on the EFC with experts at the TU

Delft as part of human capacity development.

Various aspects of the Coaltech funded research project – which included investigating the effect of an-

tiscalants on key EFC operating and performance parameters and sequential salt removal – have contrib-

uted to the broader research thrust aimed at demonstrating proof of concept for EFC as a feasible treatment

for multi-component hypersaline brines. Some of the key findings included:

figure 5: eutectic freeze crystalisationfigure 6: eutectic freeze crystalisation


The sequential removal of individual salts from a multi-component brine stream can be achieved through

strategic seeding. The seeded experiments also showed good reproducibility, demonstrating better con-

trol of the crystallizing system.

For a ternary Na2SO4MgSO4H2O system, a salt purity of 95% was obtained after only two washes.

Based on the preliminary results of the single antiscalant tested at the typical concentrations used in

industry, no significant negative effects on the key EFC operating and performance were observed.

Also in 2009, a prototype scraped stainless steel 2.5L eutectic freeze crystalliser with automated tempera-

ture and torque control with online data capturing capability was commissioned.

The construction of a state of the art low temperature laboratory – the Industrial Crystallization Eutectic

Laboratory (ICELab) – was completed and commissioned at UCT. The ability to carry out experiments in a

climate-controlled environment at temperatures down to -20˚C, significantly enhances the research capabil-

ity of the unit.

Coaltech continues to play a key role as a benefactor in developing the fundamental and applied knowl-

edge base for ultimately implementing this novel EFC technology for the treatment of hypersaline brines in

the broader context of South African mining and processing industries, and industry partners are looking at

specific solutions using this technology.

Aspects of the various research findings have already been or are in the process of being communicated

to both industry and the scientific community through media such as research reports to Coaltech, journal

publications and oral presentations at local and international conferences such as the SAIMM 2009 and

the International Mine Water Conference. From a capacity building perspective, 4 postgraduate students

continue to be actively involved in this project with one of the students successfully upgrading his MSc to

a PhD.

c. ion exchange treatment

Over the past year several BTECH Chemical Engineering miniprojects were completed at CPUT, focussing

on removing major elements from brine solutions.

Carbonation of a fixed bed of Amberlite IRA-67 resin for sodium carbonate production from sodium chlo-

ride brines was investigated. CO2 reacts with the resin, followed by the loading or ion exchange step when

the concentrated brine solution is passed through the bed, resulting in the precipitation of sodium bicarbo-

nate. The solubility of NaHCO3 in water is 9.6 g/100 g of water and the solubility of NaCl in water is 36g/100g

of water at 20 °C. The concentration of the brine solution must be high in order for the sodium bicarbonate

to precipitate. The resin is regenerated back to its free base form by using a strong base NaOH solution.

In practice, calcium hydroxide will be used as regenerant. Sodium carbonate would be recovered from the

ion exchange effluent by subsequent heating and evaporation of the solution. An exothermic reaction takes

place when the free-base resin is reacted with CO2 causing a temperature rise in the bed. If there is too high

a temperature rise in the column, it will lead to the deterioration of the resin which decreases the capacity

of the plant and will lead to down time because of the regeneration step. The temperature profile in the ion

exchange column was determined axially and radially. The highest temperature increases were obtained for

the radial configuration compared to the axial configuration. Further work is in progress to convert the NaCl

to NaHCO3.

A comparative study was done using a commercial zeolite, Faujasite, and a natural zeolite, clinoptilolite, to

determine which adsorbent was effective at removing both Mg2+ and Ba2+ from a simulated brine solution.

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The percentage removal for Mg2+ and Ba2+ were determined to be 13% and 18% respectively when com-

mercial Faujasite was used, and when natural clinoptilolite was used the % removal increased to 21% and

30% for Mg2+ and Ba2+ respectively. These results showed that the low cost natural zeolite, clinoptilolite, per-

formed better in terms of removing Mg2+ and Ba2+ from the simulated brine than an expensive commercial

zeolite. These low cost adsorbents could be utilised to remove toxic metals from mining effluents – currently

being evaluated at UWC.

Electrodialysis (ED) is well known in water treatment and has the following advantages which make it feasi-

ble for industrial use: no chemical additives required, no extensive pretreatment, the ability to simultaneously

separate a wide variety of ionic constituents and high recovery of demineralised water. A three compartment

electrodialysis cell was built. Synthetic brine (5% NaCl) was used as the central compartment solution; this

was the solution that was to be desalted. A 17 g/L Na2SO4 solution was used as the electrode rinse. Both the

centre compartment and electrode rinse solutions were recirculated back to their respective tanks. After 17

hours the electrical conductivity of the 5g/L brine had been reduced from 9.11 to 0.33 ms/cm. The electrical

conductivity had been reduced by 96 % indicating a good NaCl removal. It was thus possible to remove 96

% of the NaCl from the brine. The electrode rinse solution concentration also decreased from 17 to 2 g/L

Na2SO4. Commercial ED cells would be efficient in desalinating the brine but the cost factor and the water

recovery should not be ignored.

Ion exchangers are available as the familiar beads (“resins”) and also as very fine fibres. Advantages of fi-

bres include a relatively high osmotic stability allowing for multiple drying and moistening of the filaments as

well as an overall increase in surface area which promotes faster particle diffusion. Fibres have applications

in ion exchange operations where they will be used to desalinate or purify brines resulting from the mining

of coal and other processes. The pressure drop-flow rate relationship for fluid flow through porous fibrous

media using Darcy’s equation was established at CPUT. Non-woven and woven fibrous material (a semi-

commercial product: FIBAN and an experimental polyacrylonitrile functionalized fibre) were evaluated. The

FIBAN AK-22-1 offered more fluid resistance, implying a greater pressure drop across the material exposed

to the flow of water. This can be attributed to a smaller void volume when compared to the polyacrylonitrile

woven type of material. The non-woven fabric also had a thicker cross section when compared to the woven

type which would result in greater viscous losses due to the thickness of the material being larger and the

fluid having to travel a greater distance across the bed. This results in a greater resistance to fluid flow. The

polyacrylonitrile material appeared to have a greater porosity than the woven type due a larger superficial

velocity existing during compaction of the material when the fluid passed over it. The linear relationship was

clearly illustrated when pressure drop was plotted against flow rates. The polyacrylonitrile material had the

larger permeability of the two materials investigated. The greater pressure drop results in increased cost

expectations due to an increase in energy required to create the required fluid flow across the material. If

the method would be applied commercially, it would be necessary to take costs into consideration and in

that instance the material with the least fluid resistance (lowest pressure drop) would be recommended.

However, tests need to be performed, evaluating the flow of saline solutions across either bed in order to

simulate the treatment of brines.

The work on the Counter Current ion Exchange CCIX, by Mr Bruce Hendry and students at CPUT, has

been dormant since his presentation to Coaltech in March 2009 as the students are completing their theo-

retical course work prior to starting their projects later this year. They are available for research projects

from July 2009 again. The ideal would be to move the current CCIX rig at CPUT to an industrial site and this

will be pursued for possible installation at the Koeberg Power Station. Condensate polishing plant or the

demineralisation plant, where plant chemists could conduct routine monitoring, maintenance and sampling.

However, an additional budget allocation would be required to effect the installation.


This study, carried out between July 2008 and March 2009, was a collaborative research project be-tween the CSIR and Tshwane University of Technology, focusing on the removal of SO4

2- from acid mine drainage using the CSIR patented alkali barium and calcium (ABC) process. One of the envis-

aged benefits of using this technology is that the resultant sludges can be recycled to be reused as raw materials in the process (e.g. BaCO3). In addition, the final effluent can be used as grey water or treated to drinking water standards without generating brines.

This study focused mainly on the SO42- removal stage of the ABC process. The SO4

2- removal process involves precipitation of SO4

2- present in water as CaSO4 to generate BaSO4/CaCO3 sludge as shown in equation 1.

Ca2+ (aq) + SO42- (aq) + BaCO3 (s) -> BaSO4 (s) + CaCO3 (s) (1)

From Figure 1 it can be seen that the kinetics of SO42- removal is faster when using excess synthetic

BaCO3. In this regard, SO42- removal to levels lower than 200 mg/l is achieved in less than 1 hr using molar

ratios of [Ba2+]:[SO42-] higher than 1.

From Figure 2, the use of commercial (China) BaCO3 for SO42- removal exhibits much slower kinetics com-

pared to using synthetic BaCO3 (Figure 3). In this case SO42- was removed to below 200 mg/l in about 2 hours

when a high dosage of commercial BaCO3 was added to 1000 mg/l SO42- feed water in the [Ba2+]:[SO4

2-] molar ratio of 1.8. This indicates that a longer retention at higher dosage of commercial BaCO3 would be

evaluation of the BaCo3 process for sulphate removal on the coal mines acid mine drainage (AMD)

figure 1: effect of synthetic BaCO3-concentration on the level of SO42- removal in synthetic feed water


required for SO42- removal rate comparable to the under dosed laboratory synthesized BaCO3.

Figure 3 clearly illustrates the significant difference between synthetic and commercial BaCO3 on SO42-

removal from synthetic feed water. This difference in the rate of SO42- removal between the two products

may be attributed to the different physico-chemical properties of the two products which still need to be confirmed by further studies.

Figure 4 shows that the rate of SO42- removal from synthetic feed water increased significantly at low pH

with SO42- removed to levels below 500 mg/l after 1 hr. BaCO3 is sparingly soluble in water with a ksp value

of 5.1 10-9. The precipitation of SO42- as BaSO4 requires that Ba2+ should dissociate from BaCO3 to be able

to react with SO42-. The dissociation of BaCO3 in an aqueous solution is pH dependent. In this regard under

equilibrium conditions the laws of mass action indicates that more BaCO3 would dissociate at low pH and

figure 2: effect of commercial (China) BaCO3 concentration on the level of SO42- removal in synthetic feed water

figure 3: comparison of SO42- removal from synthetic feed water using a 1:1 molar ratio [Ba2+]:[SO4

2-] syn-thetic and commercial BaCO3


become available for SO42- removal. Thus as given in Figure 4 better SO4

2- removal occurs at pH 7.89 com-pared to pH 12.30.

An important step in the BaCO3 process for SO42- removal is the recovery and recycling of BaCO3. BaCO3

may be recycled from the BaSO4 sludge formed during the SO42+ removal step. This is achieved via two

stages; (1) High temperature thermal reduction of sludge to generate water soluble BaS (2) H2S stripping us-

ing CO2 to precipitate BaCO3 Figure 5 shows the results for electrical conductivity (EC) and sulphide during precipitation of BaCO3 from

a BaS feed solution via H2S stripping using CO2. EC gives a measure of ions present in the BaS feed solu-tion. Figure 5 shows that the EC decreases gradually from 50 000 S/cm to almost zero over 3 hr of H2S stripping. Similarly, the sulphide content drops from about 6000 mg/l to almost zero over the same period. The gradual drop in EC during H2S stripping is an indication of the precipitation of BaCO3 from Ba(OH)2 and Ba(HS)2 formed on BaS dissolution in an aqueous medium.

figure 4: the effect of pH on the rate of SO42- removal from pre-treated AMD

figure 5: electrical conductivity and sulphide content data during BaCO3 precipitation


The different aspects of spontaneous combustion, or sponcom for short, have featured on Coaltech’s R&D agenda right from the start in 1999. During 2008/09, the fight against sponcom has continued and although the magic bullet was unfortunately not found, several developments point towards a

slow but steady increase in the knowledge and skills required to eliminate sponcom one day from our op-erations.

The Sponcom Guidelines, on which the University of the Witwatersrand has been working since 2007, were unfortunately not finished during the period due to personnel problems at the University. Publication of the guidelines remains a priority for the coming year.

Hot hole blasting, reported on elsewhere in this text, was strongly driven by the committee.

During the year a number of meetings were sought or held with technology providers which the committee thought could contribute to the objectives of combating sponcom. This culminated in a workshop, organ-ised jointly by Coaltech, Anglo Coal and the Fossil Fuel Foundation, on the 24th of July, in which some of these initiatives were presented to industry representatives and further discussed and developed.

The focal point of the workshop involved a presentation and discussion from a United States-based com-pany with an international solution to coal mine fires. Known as CAFSCO, the company manufactures compressed air foam systems that have proven successful in extinguishing sponcom fires under a variety of circumstances. While traditionally used water-based foams degrade in hours, CAFSCO produces air and nitrogen foams with chemical stabilisers and infused with micro-organisms. As a result, this foam remains stable for several days, while the micro-organisms consume all oxygen in the surrounding atmosphere, thereby preventing the flow of oxygen to the combustible material.

Moving forward, CoalTech will be investing in a proof of concept review and trials into this technology.

Other topics raised at the workshop included an overview of a mine’s own experiences with sponcom, while Christophe Roelofse of Spectra Flight Aviation Services discussed a cost-effective geo-referenced thermal imaging survey technique used for sponcom identification and characterisation. Robbie Louw of Promethium Carbon concluded the workshop with a talk on the mitigation of SponCom as an ideal means to earn carbon credits through the Kyoto Protocol’s Clean Development Mechanism.

surface mining

spontaneous combustion


One of the negative consequences of sponcom is that it affects blasting of overburden and coal seams negatively. Because one cannot exactly know what is happening at the bottom of a blast hole, it may be that these holes are positioned close to the seat of heating, or intersect a crack

which is connected to a source of heating, or any other myriad of mechanisms transferring heat from spon-com to the blast hole. The result in all cases is a blast hole with an elevated temperature, and should defer one to charge such holes with explosives. Premature ignition of such holes has occurred sporadically in the past few years, fortunately without causing any serious injury. In response, the industry has, in conjunc-tion with the explosives manufacturers, developed a number of procedures aimed at reducing the risk of premature ignition. Of the principal approaches, one is based on eliminating the most sensitive links of the

initiating system (detonators and primers) from the bottom of the blast holes, and the other on monitoring the temperature of the borehole and only charging it under rigorous prescribed condi-tions.

However, these procedures cannot by themselves prevent pre-mature ignitions, as there are too many unknown variables in the blasting sequence. Some of these have to do with the lack of knowledge of the behaviour of explosives and accessories un-der conditions of elevated temperature and pressure; others with the lack of understanding of what happens in the borehole be-tween the moment that it has been charged and the moment that it is initiated. Coaltech has set out to investigate these aspects

in order to improve the safety and efficiency of blasting under sponcom conditions. To this end, Coaltech has sought the assistance of the explosives manufacturers active in the South African market, two of which have risen to the challenge and are cooper-ating in finding solutions for this pressing problem. They are Afri-can Explosives Limited (AEL) and Bulk Mining Explosives (BME), which have joined forces in exploring alternative technologies.

One avenue of research is to develop, or make available, a range of explosive products and accessories with improved heat resistance. The challenge is not so much in the chemical formu-lation of such explosives – this field has apparently been widely researched- as to develop and apply testing protocols that can unambiguously and universally quantify the degree of heat re-sistance such explosives and accessories may afford. In this re-spect, the investigation currently focusses on identifying differ-ent testing protocols and on a monitoring campaign to measure temperature and pressure at different elevations in charged blast holes.

Another avenue is the development of an early warning system that alerts the blasting crew when the temperature in one or more blast holes has exceeds pre-set temperature limits, allowing the blasting crew to take the necessary measures in time. Tests have been conducted with several versions of the device with audio alarms and further development of the technology continues, which is expected to lead to commer-cialisation of the technology.

blasting of shot holes heated by sponcom

figure 2: version 3 in field trial

figure 1: hot Eye Version 3


The final draft of this report will be available from 31 July 2009.

The focus of the study has been to identify and address shortfalls in the management of the social aspects of mine closure in South Africa, with a view to provide a pragmatic social process guide for use by closure practitioners.

As an initial step, the key principles for mine closure contained in the local and international literature were examined, in order to extract generic principles for stakeholder behaviour related to closure. Environmental issues are presented only in as far as they contribute to socio-economic stability and/or development. The relationships between the different stakeholders – especially host communities and the mining corporations – lie at the heart of the problem.

Following this, two South African coal mines in the last stages of operational life – or where closures had recently taken place – were investigated. The case studies undertaken involved a mine in a major coal mining region which was closed in 2002 and subsequently re-opened, and another in a remote part of the country which is destined for closure in 2014. A third case study was intended at the commencement of this project, but afterwards investigation proved not to be feasible.

Both international and local data was assessed, and through the use of leading-edge sociological theories guidance for closure was developed for local, pragmatic application. This guidance includes issues such as stakeholder capacitation, engagement, and partnering, with the ultimate aim of leaving communities with opportunities to perpetuate their existence, with the necessary responsibilities of all stakeholders known, understood and agreed to.

project team and contributors

Ms Julie Stacey, CSMI AssociateDr Annelie Naude, CSMI AssociateProf May Hermanus, CSMI DirectorProf Phillip Frankel, CSMI Associate

human & social aspects

the socio-economic aspects of mine closure and sustainable development

centre for sustainability in mining and industry, university of the witwatersrand


The outcome of closure has been shown to be dependent on (i) the mine’s investment in time, money and energy in dealing with social disruptions engendered by closure and (ii) the response of the community. Mine closure outcomes can be described as minimalist, compliant and sustainable.

minimalist closure compliance closure

The minimum required, such that after closure :Job opportunities have been created that are sustainable Skills development has equipped people to par-ticipate in economic activity on a sustainable basisLocal infrastructure has been developed to serv-ice social and economic needs sustainablySocial investment projects and employee wel-fare caters effectively to human needs well into the future

•

•

•

•

Mining company complies with the regulatory regime, whether or not the regulatory framework facilitates optimal social closure and sustainable development. In South Africa (the most explicit of all Southern Af-rican countries in articulating policies and targets for social and community development), this includes compliance with:

The Mining and Petroleum Resources Act (2002)The Mineral and Petroleum Resources Develop-ment Regulations (2004)Various supportive legislation and regulatory provisions related to, inter alia, procurement of services, employment equity, skills development and trainingLocal and regional developmental mechanisms – the IDP processThe Mining Charter: Broad-Based Socio-Eco-nomic Empowerment Charter for the South Af-rican Mining Industry(2005)

•

•

•

•

•

sustainable closure

Internationally, sustainable closure process can demonstrate:Ethical business practices:Fundamental human rights and respect for different values, cultures and customs;Valid data and sound science:Continual improvement in health, safety and environmental performance:Biodiversity and integrated land-use planning:The social, economic and institutional development and long-term viability of communities:That oppression and inequality is tackled in a purposeful, continuous, comprehensive and action-oriented manner (Twelvetrees, 1991).

In the local context, sustainable closure processes also:Require that closure is not “simply” skilling people or providing jobs, but provides for long term economic diversificationReflect concrete social realities rather than vague and standard prescriptionsAlign indigenous South African social conditions with international best-practiceRepresent site specific frameworks and strategies derived from systematic developmental research, that are usable on a micro-managerial, step-by-step sequential or concurrent basis, andAre deployable on a rehabilitative basis, in cases where closure turns out to be unsustainable

•••••••

•

•••

•


problem definition

Currently it is estimated that approximately 50 million tons of coal is transported by road, predomi-nantly in the Witbank, Middleburg and Bethal areas of Southern Mpumalanga. Due to the large vol-umes, the resultant road damage problems associated with transport and rising costs puts the coal

industry under increasing pressure to find viable and sustainable alternative modes of coal transportation.

1.

transportation

road damage

figure 1: typical road damage caused by coal trucks


The aforementioned scenario is further complicated in that current coal reserves are nearing depletion. It is envisaged that new coal reserves will be unlocked from other areas within South Africa, including the Water-berg area, some 400km away from the current mining activity. Furthermore, these new reserves would have to be transported to, amongst others, the Southern Mpumalanga area to sustain the production of several power stations, as well as export terminals such as Richards Bay.

In this light, Coaltech requested an independent coal transport study to identify alternative transport modes and technologies, with the aim of determining which technologies are best suited for specific transport re-quirements. These transport requirements may vary according to the lead distance, terrain, throughput requirements and geographical location, to name but a few factors. It is the intention of the study to provide guidance in terms of selecting the most appropriate technology that would best satisfy these requirements in a cost effective and safe manner, while minimising any negative socio-economic impacts.

objectivesThe objective of this project is to produce a study on alternative coal transport modes that could be employed by the coal industry, so that the following needs are fulfilled:Provide the Chamber of Mines’ Colliery Committee with information to support their policy decisions with respect to various coal transport modes;To test the feasibility and applicability of suggested transport modes at various distances;To highlight transport modes that may require further research and investigation.

project scopeThe project scope takes into consideration the problem definition and objectives of the study, which will

be delivered by 30 September 2009. In essence, a high level desktop study and primary research is to be conducted, subject to the following scope inclusions and exclusions:

3.1 scope inclusionsThe following aspects with respect to the study are included in the scope of this project:Conducting desktop and primary research into alternative transport options, their characteristics, ad-vantages, disadvantages, costs and socio-economic impacts;Investigating the applicability and feasibility of each coal transport mode suggested;Comparing the identified transport options against the same evaluation criteria;The production of an interim report to be reviewed by the Coaltech Technical Committee;The production of a final bound report containing the findings of the study.

3.2. scope exclusionsThe project is intended to provide an independent high level view, and specific scope exclusions are as follows:Determining the best transport option for specific applications in mind;The investigation into the optimisation of the current coal transport network;The recommendation of specific infrastructural investments.

2.1.

2.

3.4.

3.

••

••••

•

•••


research deliverablesThe physical deliverables for the project includes the following:

The production and submission of an interim research report to be reviewed by the Coaltech Technical Committee;The production and submission of a final bound research report containing the findings of the study, to be approved by Coaltech.

The content of the final research report will focus on addressing the following requirements:

To provide a list of all available coal transport options;To provide an indication of the feasibility and applicability of each transport option at various distanc-es.To highlight novel transport options that might need further research and investigation;To provide a completed evaluation matrix that compares all the identified transport options against each other, based on a set of predefined evaluation criteria.

research methodologyCoaltech employed the supply chain specialist company, Crickmay & Associates, to conduct this trans-

port investigation and supplied them with a list of companies, primarily Coaltech members, as points of contact within the wider coal industry, to participate in and contribute to this initiative. The research was divided into the following areas:

Task No

Task Description Expected Result Deliverable

1 User Requirement Definition Coaltech meetings held and agreed project approach finalised

Documented project approach

2 Initial Information Gathering Interviews with industry experts completed

Minutes of meetings with industry experts

Identification of initial transport option list completed

Primary list of transport options

3 Desktop Research Primary desktop research com-pleted

Desktop research notes

Identification of additional trans-port options completed

Amended list of transport options

4 Primary Research Planning of interviews and sched-uling of meetings completed

Minutes of meetings with industry transport experts

Interviews with technology ex-perts done

Primary research notes

5 Define Research Parameters Evaluation matrix developed Approved evaluation matrix

6 Research Evaluation Technology evaluation and report development completed

Populated evaluation matrix

Project quality assurance Interim project report

7 Report approval, supplementary research and report amendment completed

Final research report

Project quality assurance done

table 4: research breakdown

4.

I.

II.

I.II.

III.IV.

5.


5.1. evaluation criteriaIn order to accurately compare the potential of each transport mode, it is imperative that these technolo-

gies are evaluated against the same criteria. The following table provides a brief summary of the evaluation categories:

No Category Description

1 Cost Capital Investment Cost

Operating Cost

Maintenance Cost

2 Capacity Capacity per Unit

Maximum Transport Capacity

Throughput Rate (hourly / daily)

Material/ Article Size Restrictions

Minimum / Optimum / Maximum Transport Distances

3 System Characteristics Advantages

Disadvantages

Optimum Operating Conditions

Geographical Layout Requirements / Terrain / Typography

4 Safety Impact Public Safety

Operator Safety

5 Healt Impact Public Health

Operator Health

6 Environmental Impact Environmental Impact / Damage

Possible Pollution

7 Social Impact Displacement of Settlements

Restriction of Movement

Prevention of Normal Lands Usage

8 Economic Impact Possible Job Creation Opportunities

Impact on Economy of the Area

9 Further Reasearch Required

Current State of Technology

Fundamental Research

Testing / Pilot Applications

Estimated Research Cost and Durationtable 5: evaluation category summary


progress to dateThe research is currently ongoing and the final comparisons and evaluations have not been completed,

although the following table presents a short summary on some of the technologies that have been identi-fied and researched to date.

No Transport Mode Short Description

1 Aerial Ropeways A ropeway conveyor is essentially a subtype of cable car, from which containers for goods, rather than passenger cars are sus-pended.

2 Barges A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods.

3 Coal Log Pipelines (CLP) The CLP concept presses coal into the form of circular cylinders - coal logs - so that coal can be transported by water flowing through a single underground pipe.

4 Conventional Conveyor A conveyor system consists of mechanical handling equipment that moves materials from one location to another, via a belt that moves across rollers.

5 Deep Sea Shipping Ocean transport of coal via ships

6 Intermodal Freight Transport Systems

Intermodal freight transport involves the transportation of freight in an intermodal container or vehicle, using multiple modes of trans-portation (rail, ship, and truck), without any handling of the freight itself when changing modes.

7 Magnetic Levitation Systems The Mag-Lev Transport System uses magnetic levitation technology that allows noncontact, frictionless conveyance of a levitated body within a dedicated transit corridor. The mag-lev technology utilises two types of permanent magnets coupled with an electronic posi-tion control system to achieve noncontact levitation.

8 Merry-Go-Round Trains (MGR) A merry-go-round train (MGR) is a block train of hopper wagons which both loads and unloads its cargo while moving.

9 Performance Based Standard (PBS) Vehicles

Performance Based Standards (PBS) brings a different approach to vehicle regulation. It focuses on how the vehicle behaves on the road, rather than how big and heavy (length and mass) it is, through a set of safety and infrastructure protection standards. In other words, PBS governs what a vehicle can do, not what it should look like. In the context of this report, PBS vehicles operate on public roads, but they generally carry much larger payloads than conven-tional vehicles.

10 Pipe Conveyors Pipe conveyors are similar to conventional conveyors, but the belt is rolled to form a closed pipe. Because of this closed pipe shape, the transportation is dust free and the material is protected from envi-ronmental influences. This system is ideal for large inclines, as well as routes with multiple bends.

11 Rail Rail transport is the conveyance of goods by means of wheeled vehicles running along railway lines.

12 Rail-Veyor Rail-Veyor moves materials, using a light rail track system with a series of two-wheeled, inter-connected cars that typify a long, open trough moving along the track. Individual cars are loaded and offloaded while moving, by turning the track upside down like a roll-ercoaster, which allows the load to be tipped by gravity. The system is designed to operate automatically, without a driver, via a control room.

6.

table 6: summary of technologies


No Transport Mode Short Description

13 Road The transportation of material by truck, through a network of public roads. Typically used where haul distances and ship-ment sizes are small.

14 Road Trains A road train is a trucking concept used in remote areas - it consists of a conventional tractor unit, but instead of pulling one trailer or semi-trailer, the road train pulls two or more of them, thus resulting in a substantially larger payload. Road trains in the context of this report run on privately owned roads

15 Rope Conveyor (RopeCon) RopeCon long-distance, continuous conveyor system, suit-able for the transportation of bulk materials and unit loads of any kind, via a suspended cable system.

16 Slurry Pipelines A slurry pipeline is used to transport coal, where crushed coal is mixed with water and mixed into a slurry and then pumped over a long distance through a pipeline. At the end of the pipeline, the material is separated from the slurry in a filter press to remove the water. Water is usually subject to a waste treatment process before disposal or return to the original station.

17 Tube Freight Transportation Systems Tube freight transportation is a class of unmanned transpor-tation systems in which close-fitting capsules, or trains of capsules, carry freight through tubes between terminals. The system is either pneumatically powered or it uses capsules that are electrically powered, running in a tube about two meters in diameter. The system can be thought of as a small unmanned train in a tube carrying containerised cargo.

The following pictures and photographs show identified systems in operation:

figure 2: pipe conveyor


conclusionAlthough this transport investigation is not completed yet, it is becoming increasingly clear that there is

no single transport technology that could cost effectively satisfy all the divergent transport requirements, across all distances, for all coal sizes and across all types of terrains. The optimum coal transport solution lies in the effective combination of all the available technologies into an integrated and well managed net-work, where individual technologies are applied in applications where it is best suited.

This approach allows for the safest and most cost effective transport application between each source and destination, with the lowest socio-economic impact, while protecting and enhancing the available trans-port infrastructure. The question remains, which technology for which application?

Coaltech is eagerly awaiting the successful completion of this research project, with the expectation that these questions will be answered.

7.

figure 3: coal road train figure 4: aerial ropeway

figure 5: rail-veyor

figure 6: conventional road and rail transport


alleviation of compaction

investigating the alleviation effect of different grass species root development on compacted rehabilitated soil


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the influence of different mechanical soil disturbance techniques and incorporation of organic matter on compaction alleviation


animal production on irrigated rehabilitated land


Figure 16: Exclosures used to do pasture evaluation while excluding the animal


Figure 19: Germination studies conducted using water with different levels of salinity water

evaluate the scope of gypsiferous mine water on the germination and establishment of other pasture species, to be selected for animal production under the irrigation pivot system


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