VOLUME 50 . SEPTEMBER 2017

INSIDE:

New Chief Executive Officer I 1Mahlako Mathabatha

The CGS launches the marine geoscience South African Nearshore Mapping Programme I 2Hayley Cawthra

PGM tailings as potential secondary metals/mineral resources for sustainable development I 4Frédéric Doucet/Sameera Mohamed

CGS interns take centre stage I 6Mahlako Mathabatha

Petrographic services of the Laboratory I 7Nosibulelo Zilibokwe

Specialised XRF spectrometry services I 8Corlien Cloete

New Chief Executive OfficerThe Council for Geoscience is proud to welcome Mr Mosa Mabuza as the newly appointed Chief Executive Officer. Mr Mabuza was seconded to the organisation in November 2016, after the retirement of the then Acting CEO, Mr Simon Sikhosana. Mr Mabuza was permanently appointed in his new role in July 2017.

Mr Mabuza is a qualified geologist with extensive exploration experience in multiple regional jurisdictions including SADC, West Africa and Canada, among others.

Before 2006 he had held various positions at De Beers and Anglo American, when he was appointed as the Director of Mineral Economics in the former Department of Minerals and Energy. Mr Mabuza officially assumed the role of Deputy Director-General of Mineral Policies and (Investment) Promotion in 2012. During his tenure as an official in the Department of Mineral Resources, Mr Mabuza was charged with the responsibility of leading the technical teams that delivered, inter alia:

• the draft strategy for sustainable development and meaningful transformation of South Africa’s mining industry with an emphasis on competitive growth and transformation;

• the Mineral and Petroleum Resources Development Amendment Bill, to be finalised by Parliament; and

• an assessment of the impact of the implementation of the Mining Charter and its amendments in 2010 and 2017 on industry.

Mr Mabuza represented the Department of Mineral Resources on the Boards of a number of State-Owned Entities, including the Council for Geoscience, Mintek and the South African Diamond and Precious Metals Regulator.

During his tenure as Acting CEO at the Council for Geoscience, Mr Mabuza worked tirelessly with staff of the organisation to champion the refocussed geoscientific programme in support of Government’s national developmental priorities.

Mr Mabuza asserts, “I am profoundly honoured to join the CGS family officially and look forward to working with colleagues in the organisation as well as our shareholders and stakeholders to advance the geoscience field and integrate the output to progress socio-economic development imperatives”.

Mr Mosa Mabuza

For more information contact:Mahlako Mathabatha Marketing & Communication+27 (0)12 841 1220mmathabatha@geoscience.org.za

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The CGS launches the marine geoscience South African Nearshore Mapping ProgrammeIntroduction

The South African Nearshore Mapping Programme (SANMAP), conceptualised and initiated in April 2016, aims to conduct a mapping programme covering the entire South African continental shelf, in line with the new strategic plan of the Council for Geoscience. SANMAP has a clear vision of producing seamless onshore–offshore geological maps of the seafloor in view of boosting the blue economy. These maps will be displayed on a scale of 1:50 000 and will be merged with the onshore sheets extending to the coastline.

The need for the acquisition of high-resolution, high-quality marine geophysical and hydrographic data is apparent in the range of applications that can be derived from the data. These include applications for offshore mineral and commodity exploration and identification, the delineation and designation of marine protected areas, utilisation in geohazard assessments, the quantification of sediment migration, infrastructural planning on coasts and the provision of a baseline for monitoring global change. SANMAP aims to provide essential geophysical and geological data both for ocean and coastal research and management, to stimulate and grow research and to raise public education and awareness of issues pertaining to the coast and the ocean. New mapping is being carried out in tandem with analytical work on existing datasets and the development of a robust data management strategy. The six key focus areas identified are marine technology, innovation in mapping, research, capacity building and training, ocean governance and data management.

The mainland of South Africa has a coastline of some 3 000 km, with 40% of the population living within 100 km of the shore. Coastal areas have increased infrastructural requirements, with issues such as renewable energy resources, desalination plants, petroleum production

platforms and pipelines, submarine telecommunication cables and port and harbour entrances all requiring a baseline understanding of the marine environment. The seafloor contains rich palaeoclimate archives, as sea levels were lower than present for ninety per cent of the Quaternary Period, exposing a now-submerged terrestrial landscape. During the time of the Last Glacial Maximum, the exposed continental shelf had added 80 000 km2 to the coastal plain of the Agulhas Bank alone. The opportunity to study these archives is limited by a general lack of high-resolution geophysical data which this programme aims to address. In the light of global climate change and an associated rising sea level, coastal vulnerability warrants meticulous consideration.

Global trends in marine geology are heading in the direction of large-scale offshore mapping programmes. Numerous countries either have completed multibeam bathymetric maps

of their offshore territories or are in the process of collecting these data. The Operation Phakisa initiative of the South African Government strongly bolsters the need for this work at the Council for Geoscience.

Materials and methods

Methods applied in new marine geophysical surveys incorporate the application of multibeam bathymetry, side-scan sonar, boomer and pinger subbottom profiling and marine magnetics. The Council for Geoscience surveyed the Table Bay seafloor in March and April 2017, applying all of these techniques. Data curation is currently being undertaken through an Esri portal that is designed to accommodate historical archives as well as the newly acquired datasets. Existing marine geophysical datasets are used to interpret the geological setting of the continental shelf, palaeo-environments are modelled through multidisciplinary

Planned coverage of offshore mapping blocks for the first two years of the SANMAP programme.

GeoClips I 3Geoclips - Volume 50 - September 2017

collaboration, samples are being analysed for indicators of palaeoclimate and palaeo sea level reconstructions are underway.

Ongoing research in marine geoscience

The first survey of Table Bay, still to be completed within its map sheet area, shows a predominantly rocky seafloor that is relatively sediment starved. Although there is a paucity of well-preserved outcrops of Malmesbury Group metasedimentary deposits onland, these deposits are well exposed on the seafloor. The Table Bay datasets have been integrated with previous work carried out by Michael MacHutchon and Philippe van den Bossche around Robben Island and by Wilhelm van Zyl, who is studying the Atlantic Seaboard. Between the entrance to the commercial harbour and the main (outer) breakwater a number of erosion features have been mapped, including pockmarks caused by the action of dredging pipes. Three palaeochannels which have been mapped surficially and seismically on the seafloor are being linked to the onshore fluvial systems. Considering heritage resources on the seafloor, shipwrecks have been identified and mapped in Table Bay. Wilhelm van Zyl and Michael MacHutchon are working towards understanding beach nourishment and sediment dynamics in the Peninsula and wave models will later be calculated using the acquired high-resolution bathymetry.

Hayley Cawthra is carrying out an investigation of Pleistocene sea levels in South Africa by using surficial marine geophysical datasets (multibeam bathymetry and side-scan sonar) from Cape Agulhas to Port Elizabeth, where deposits remaining from past low sea levels have been preserved on the continental shelf. Southern hemisphere land masses are important for understanding sea level changes and offer the opportunity of reconstructing long-term eustatic sea level fluctuations where tectonic stability can be demonstrated and compared with the formerly glaciated continental regions. The south coast and adjacent shelf provide an ideal locale to examine

Three of the five suites of geophysical equipment used in marine mapping. Top: winch and side-scan sonar,

middle: marine magnetometer and bottom: multibeam echosounder.

Data coverage on the Table Bay seafloor, shown here as a multibeam bathymetry DEM. The colour ramp

increases from shades of blue (deep) to red (shallow). Processing and visualisation: Michael MacHutchon

and Leslee Salzmann.

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sea level fluctuations. The marine geophysical datasets, which were ground truthed by scuba diving, provide a means to understand past fluctuations in this region. In addition to palaeo sea levels, sequence stratigraphy derived from subbottom profiles is being used as a basis for identifying locations for coring on the shelf where terrestrial sediments have been deposited and preserved, and palaeoclimate studies are under way. Ongoing work in this regard through extensive international collaboration with colleagues in Germany has shed light on Late Pleistocene and Holocene

For more information contact:Hayley Cawthra Acting Manager: Western and Northern Cape Regional Offices+27 (0)21 943 6700hcawthra@geoscience.org.za

PGM tailings as potential secondary metals/mineral resources for sustainable developmentNumerous countries face economic, environmental and health-related challenges, which are associated with the management of large volumes of solid mine residues. This is particularly relevant in South Africa, which is a large global producer of platinum, gold and chrome. An aspect that is often overlooked in the life cycle of sustainable mine residues management, and which can resolve these challenges, at least in part, is that mine residues can also represent untapped secondary resources for valuable minerals and metals.

Several countries are developing integrated processes for the recovery of metals from bauxite residue and copper tailings, and for the conversion of bauxite tailings to highly crystalline zeolites. Cyanidation tailings have also been used to synthesise nano-iron red oxide pigment and iron ore tailings have served as a secondary resource for the synthesis of iron oxide and, ultimately, magnetic graphene.

While the full exploitation of such residues will require a paradigm shift in the field of mine waste management, this is one of the central issues of eco-efficient mining in the so-called “green mining” arena, which is already gaining momentum in Europe, Canada and Australia. Another aspect of waste valorisation, which is emerging as an

Process flow diagram for the multistage extraction of major elements from PGM mine tailings (*MTtct contains

M-SO4 compounds, where M is a metal).

important area for metal recovery, is “landfill mining”, a concept in terms of which minerals or other solid natural resources contained in waste materials that previously had been disposed of by burying them in the ground are extracted for resource recovery. However, economically successful recovery of minerals and metals from solid mine residues may be less challenging than

from landfills, given the insufficient information regarding the contents of landfills in regard to valuable elements, such as concentrations, types and location of metals in the landfill sites.

The Council for Geoscience is involved in several projects aimed at developing innovative technological processes to enhance the recovery of metals

climatic and environmental fluctuations in southern Africa.

A third research angle currently being explored is using new backscatter/snippets from multibeam bathymetry to assist in developing sophisticated methods in predictive benthic habitat mapping on the South African shelf, starting with Table Bay. When multibeam bathymetric data are acquired, the backscattered waves are generally lost to the water column. The strength of return and the amount of absorption and reflectivity depend on the geological

substrate and on the textures of communities growing on these deposits. Predictive mapping involves working on processing the snippets and backscatter and this is being carried out by Ph.D. student Talicia Pillay.

Reagent recycling

(NH4)2SO4 (s)

(NH4)2SO4 (s)PGM tailings

NH3 (g)Thermochemical

solid-solid reaction

M-SO4 dissolution

Solid-liquid separation

MTtct*(s)

Al2O3

Residue M- and SO4 - bearing solution

Controlled synthesis of alumina

Controlled synthesis of nano-Fe adsorbents

Applications in wastewater remediation

GeoClips I 5Geoclips - Volume 50 - September 2017

and minerals contained in mining and industrial residual waste and process residues, to synthesise useful products and to solve environmental issues. An example of process residues studied includes an investigation of PGM tailings.

South Africa accounts for 96% of known global reserves of platinum group metals (PGMs). In 2011, research estimated that the country’s mining operations associated with the primary production of PGMs from the Merensky, Upper Group 2 (UG2) and Platreef operations in the Bushveld Igneous Complex (BIC) generated over 77 Mt of fresh tailings per annum. In 2008, Anglo Platinum had already reported a cumulative 730.8 Mt of generated tailings. The ever-increasing volumes of piled PGM tailings pose considerable challenges to the mining sector. These alkaline tailings are regarded as hazardous waste which must be managed properly to avoid contamination of the local surface and groundwater. However, these high-tonnage materials generally contain elevated concentrations of iron, aluminium, chromium and magnesium, and low to moderate amounts of titanium and other valuable elements, depending on their origin. They could therefore be regarded as an economic resource rather than as waste, provided suitable economically viable processes can be developed to extract the metals and minerals.

In 2013, the Two Rivers Platinum Mine commissioned a recovery plant to reprocess its tailings to recover the chromite. Tailings from other mining sectors (e.g. chromium, vanadium) within the BIC can also contain valuable elements or minerals. For instance, Jubilee Platinum, also a platinum-focussed mining and exploration company, was busy commissioning the largest PGM beneficiation plant of surface chrome tailings in the country for the production of platinum, palladium, rhodium and gold concentrates using the ConRoast process. Although most of the focus has been on the recovery of precious and ferrous metals, the extraction of, for example, non-ferrous metals and minerals from tailings is rapidly emerging as a new research area, mostly owing to environmental

considerations associated with active but also with derelict and ownerless mines. An example is the recent interest taken in the CO2 mineralisation potential of PGM tailings owing to their Mg-rich mineralogy. However, this approach can only become feasible and economically viable if it is integrated with the co-recovery of, for example, high-value precious and specialty metals, and low-value major elements that can be converted to value-added products. For instance, elements such as iron could be used by the iron and steel industry or as feedstock for the synthesis of nanobased materials for waste water treatment processing, while aluminium could be used to prepare alumina, for example. Magnesium could be converted to magnesite (MgCO3) as a CO2 sequestration mineral technology. These integrated processes should also achieve high yields, high energy efficiency, minimal emissions and low volumes of final waste. All these envisaged modes of use of the tailings could significantly reduce the volumes of tailings, and could contribute to the sustainability of the mining sector and to the reduction of penalties imposed on mines for waste accumulation.

To date, acid leaching using both strong inorganic and organic acids has been shown to be of limited value for cation

extraction from PGM tailings. In recent years, the Council for Geoscience has focussed on identifying and testing a potentially promising thermochemical extraction process that makes use of a widely available, low-cost, recyclable chemical agent. Ammonium sulphate salt ((NH4)2SO4) meets all three criteria. Its thermal solid-solid reactions with silicate and oxide minerals for elemental extraction have been extensively studied for over thirty years. In recent years, its reactivity with serpentinite rocks from Finland and other countries has also been the focus of much attention at the Åbo Akademi University in Finland, primarily in the context of mineral CO2 sequestration. However, the reactivity of silicate and oxide mineral assemblages present in PGM tailings (e.g. orthopyroxene, clinopyroxene, anorthite) with (NH4)2SO4 for cation extraction has yet to be elucidated.

Some of the extraction efficiencies achieved so far includes 60% for aluminium and 80% for calcium; 35% iron and 32% silicon were also extracted alongside chromium (27%) and magnesium (25%). Thermochemical treatment of PGM tailings with (NH4)2SO4 induces the extraction of metals from the tailings matrix, with the subsequent formation of well-defined, water-

FE-SEM micrographs illustrating well-defined, water-soluble, micron and submicron sized, hexagonal metal

(Fe, Al, Cr and/or Mg) sulphate structures formed during the thermochemical processing of PGM tailings with

ammonium sulphate.

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For more information contact:Frédéric Doucet/Sameera MohamedWater & Environment +27 (0)12 841 1300/1335fdoucet@geoscience.org.zasmohamed@geoscience.org.za

soluble, micron and submicron sized, hexagonal metal (Fe, Al, Cr and/or Mg) sulphate structures.

Thermochemical treatment using ammonium sulphate may therefore represent a promising technology for

extracting valuable elements from PGM tailings, which could be subsequently converted to value-added products. Further development of this integrated process, which aims at achieving the full potential of utilisation of PGM tailings, is currently underway.

CGS interns take centre stageOn 6 and 8 June 2017, 20 interns were given the opportunity to present their work to a panel of internal evaluators which consisted of Executive Management, Human Resources representatives and scientists from various disciplines and projects. The purpose of the session was to provide the interns with an opportunity to showcase their resumés, experience gained, skills developed, achievements and lessons learnt during the course of their internship at the Council for Geoscience. The following staff members were part of the panel: Mr Mosa Mabuza, Mr Fhatuwani Ramagwede, Ms Malefshane Kola, Mr Dibela Matsepe, Dr Bisrat Yibas, Dr Thakane Ntholi, Dr Gerrit de Kock, Dr Chris Hatton, Mr Nick Baglow, Dr Nandi Malumbazo, Ms Valerie Nxumalo, Ms Refilwe Shelembe, Ms Zandile Kota and Mr Neo Moabi.

Throughout their internships, many of the interns had been placed in different projects to expose them to various scientific disciplines. The interns began by introducing themselves to the panel, stating their background, the number of years of their internship, their respective roles within the project(s) as well as the various skills or areas that they had developed. At the start of their presentations, many of the presenters were nervous although faced with the familiar faces of their peers, supervisors and the Executives. Some of the presentations were enthralling while others demonstrated a need for more dedicated support and mentoring. Once the interns had completed their presentations, they had the unenviable task of answering a multitude of questions from the evaluators and Executives.

The CEO, Mr Mosa Mabuza, took to the podium to thank the interns for honouring

the invitation and giving their best efforts in the presentations. He highlighted the importance of designing the internship programme in such a way that it exposes the interns to as many opportunities as possible, allowing them to bring a fresh approach to how things are done, as solutions are constantly being sought.

He added that the strategic re-orientation of the organisation will seek to place the field of geology as a central focus of the country. His message to the interns

A new generation of geoscientists with the team of experts.

Hellen Chukudu presenting to a panel of internal

evaluators.

For more information contact:Mahlako Mathabatha Marketing & Communication+27 (0)12 841 1220mmathabatha@geoscience.org.za

was to continue their hard work with integrity, professionalism and discipline. He urged them never to compromise their professional integrity. He explained that an executive decision had been taken to extend their contracts by another year while the organisation finalises the structure in the light of the new extended mapping programme. Once sufficient funding has been secured, the Council for Geoscience will consider employing them on a permanent basis. He urged the interns to consider staying on, as the Council for Geoscience proceeds to shape and advance the earth sciences to bring this discipline back into sharp focus in South Africa and the world.

GeoClips I 7Geoclips - Volume 50 - September 2017

Petrographic services of the LaboratoryThe main focus of the petrography section of the CGS Laboratory is the preparation of thin sections and ore mounts for clients. The preparation process encompasses the following four stages: cutting, mounting, lapping and polishing. The petrography section also accommodates materials that may have pores, cracks or that are poorly consolidated by using a vacuum impregnated with epoxy prior to grinding. The prepared thin sections are often used for rock testing and for exploration purposes. Most of the currently explored deposits contain finely disseminated grains accompanied by complex textures that can be difficult to identify. Thin section analyses ultimately benefit the client by providing accurate information about the rock.

The thin section preparation laboratory has over 40 years of combined experience with well-trained technicians who work diligently to create custom petrographic products. The laboratory offers a wide range of preparation options to best suit the needs of the client. There are two types of specimen routinely prepared for analysis — thin sections and polished bulk/stub specimens. Thin section specimens are extremely thin, generally 30 μm or thinner, and are typically examined using a transmitted polarised light microscope mostly for silicate minerals. However, for polished stub specimens, the surface is prepared for examination with a reflected polarised light microscope. This method is very useful for targeting many kinds of opaque minerals such as sulphides and oxides.

In 2016, the petrography section acquired a new microscope for conducting petrographic analyses. The microscope is a BX 43 Olympus model with a dedicated camera utilised in conjuction with a stream software package to produce high-resolution images. With this microscope, the petrography section is able to provide services in fields that range from exploration to mining and beneficiation to a large variety of internal and external customers in the minerals industry. The capabilities of the microscope include the generation of multiple views, transmitted and reflected in plane polarised light

The photomicrographs show thin sections of various rock types viewed under transmitted light (a–e) in crossed

polarised light (XPL); (f) was viewed under reflected light in plane polarised light (PPL). (a) The thin section

shows a generally medium-grained rock with feldspar twinning within microcline (centred view), some perthite

exsolution textures (far left) and plagioclase multiple twinning known as albite (seen at the top and bottom left

of the photo). (b) Strongly pleochroic elongated crystals of hornblende and biotite occurring intergranularly

with quartz. c) Clinopyroxene (cpx) as the host, ophitically and subophitically enclosing plagioclase laths.

d) Generally moderate to poorly sorted marine sandstone with well-rounded quartz crystals in a calcite (clt)

rich matrix. e) Very fine-grained clay rich matrix with some quartz and feldspar (feldspar occurs as fine-

grained crystals which makes is difficult to precisely distinguish whether it is plagioclase or sanidine, XRD is

recommended in this case). f) Multimineralic sulphide grain locked in a silicate (appearing grey). The sulphide

shows three phases; pyrrhotite (po) – greyish pink, pentlandite (pn) – light yellow and chalcopyrite (cpy) –

yellow. All images viewed at 4X magnification.

BX 43 Olympus petrographic microscope.

a b

c d

e f

(PPL) and crossed polarised light (XPL). In addition, the petrography section is capable of providing a variety of magnified photos in order to support informed decision making.

The petrographic description includes the quantification of basic mineralogy (i.e. estimated modal abundance), mineral identification (including both gauge and opaque phases) and other factors such as average grain size, shape, texture and mineral associations. In view of

po

pn cpy

If you are not on our mailing list and you would like to receive a copy of GEOclips, please send an e-mail to:Mahlako Mathabatha, Marketing & Communication, mmathabatha@geoscience.org.za

Private Bag X112, Pretoria 0001, South Africa / 280 Pretoria Street, Silverton, Pretoria 0184, South AfricaTel: +27 (0)12 841 1911 / Fax: +27 (0)12 841 1221 / www.geoscience.org.za

Specialised XRF spectrometry services

For more information contact:Corlien CloeteLaboratory+27 (0)12 841 1334hccloete@geoscience.org.za

X-ray fluorescence (XRF) spectrometry is a robust analytical method used to identify and quantify elements of the periodic table. The PANalytical Zetium was purchased and installed during May

2016 at the CGS Laboratory. The new XRF spectrometer complements and, in time, will replace the two ten year old XRF spectrometers of the laboratory. The instrument is the first XRF spectrometer

with both sequential wavelength and energy dispersive detection systems in South Africa and has been successfully calibrated to analyse major elements on glass disks and trace elements on pressed powder pellets. The spectrometer has already analysed more than 2 000 samples mostly for major elements in samples from the raw materials industry. The two analytical methods are being prepared for ISO 17025 accreditation.

This instrument provides the CGS Laboratory with the opportunity to be one of the leaders in XRF spectrometry in South Africa.

Masibi Matji, Esau Tsaagane, Stella Burger, Tshepo Rantsane and Corlien Cloete (Themba Mguni was

absent) beside the PANalytical Zetium XRF spectrometer.

For more information contact:Nosibulelo ZilibokweLaboratory+27 (0)12 841 1012nzilibokwe@geoscience.org.za

the fine-grained nature of the minerals that constitute a rock, the use of optical microscopes in the identification of minerals and their textural relations is paramount in mineralogical investigations.

The petrographic description of rocks is fundamental to research at the Council for Geoscience and is always supported by X-ray diffraction (geochemical analyses), which forms a major part of the activities of the CGS Laboratory.

Services offered include the preparation of:

• polished thin sections • uncovered/standard thin sections • covered thin sections, and • polished bulk/stub specimens.

Available analyses comprise detailed and concise petrographic descriptions. Additional analytical analyses are performed by the mineral separation laboratory, where the following techniques are utilised to separate mineral fractions:

• Gravity separation using a Wilfley shaking table

• Heavy liquid separation using a dense media

• Magnetic separation using a Frantz magnetic separator.