Journal of Scientific & Industrial ResearchVol. 60, May 2001, pp 416-420

SPM is the Major Pollution in Open Cast Mining - A Case Study

G K Banerjee" K K Srivastava tand M K ChakrabortyCentral Mining Research Institute, Barwa Road, Dhanbad 826001, India

Received: 23 October 2000; accepted: 25 January 2001

Presents the emission factors of the twelve open cast mining activities, identified as the most significant sourcesof air pollution in and around the mining areas. The Pasquil and Gifford formula has been used to compute theemission rates for the ground level emissions. The findings of the study reveal that haul roads and transport roads arecontributing maximum of SPM concentration among all other mining activities. The total emission rate of the haulroads and transport roads is 2.3749 gIs, whereas the grand total of the emission rate from overall mining activities is25.7117 gls.Moreover, it is found that the emission rates of NOx and S02 are very negligible, which are only 0.7813gls and 1.2785 gIs, respectively. The emission rates of SPM, NOx and S02 due to overall mining activities of theopen cast mining are compared through a pie diagram. Finally, the study concludes that the SPM is the majorproblem of an open cast mining and it can be controlled through immediate short-term and long-term biologicalcontrol measures.

Introduction

In many countries mining has been an old industry ofmankind. Since industrial revolution, coal mining hasbecome important industry in many developed and de-veloping countries. Though the coal is a basic source ofenergy in most of the countries concerning with powerand economy, the word "coal mining" is still remains adirty one in the dictionary of the people.

As mining of any mineral is always associated withpollution problem, especially air pollution due to par-ticulate matters of size of aerodynamic less than J0/1diam, coal mining is not excepted from such a problem.Large quantities of dust are produced and released inthe working atmosphere during mining and handling ofminerals. Mining activities are accompanied by a vari-ety of environmental impacts, which can contribute to-wards degradation of environment as a whole. The pro-cess of environmental degradation that starts with theextraction of minerals results in land degradation andaddition of pollutants to the atmosphere. Dust is alwaysgenerated whenever coal is subjected. to such operation

*Author for correspondencet Department of Chemistry, Vinoba Bhave University,

Hazaribag ( India)

as crushing, drilling, cutting by virtue of its brittle char-acter. Suspended particulate matter (SPM) is compositegroup of substances, liquid or solid, dispersed in the at- .mosphere. The most significant fraction of SPM is therespirable size that is larger than about 0.1/1 and smallerthan 5.0/1. The SPM is of different size and shapes. Theparticles of importance in air pollution are those withsize between 0.1-10/1. There are the only particles withthis size range which remain suspended in the atmo-sphere, whereas the larger particles settles down.

In open cast mining operation enormous quantity ofdust of various sizes gets into the environment. Coalsobtained from the open cast mining undergo transporta-tion and storage, size reduction and classification, wash-ing and concentrating, mixing and drying operations'.About 10 to 100 g of dust below 5 /1 is produced pertonne of coal mined and about 1per cent of this is dis-persed as airborne dust'. The airborne dust in the ambi-ent air is an important parameter for the study of healtheffects. The air pollution by SPM has attracted muchinterest, as recent epidemiological studies have shown astrong association between SPM concentration in ambi-ent air and effect on human air ways and mortality'".The most important size fractions causing health effectsare that of thoracic particle (aerodynamic diam less than10/1;PMIO) and of fine particles (aerodynamic diam less

BANERJEE e1 a/.: SPM- TH E MAJOR POLLUTION IN OPEN CAST Ml lNG 417

than 2.5 ~ ; PM2

) 9

. The uncontrolled SPM not onl y creates serious health effects but also affects the pro­ductivity through poor visibility, breakdown of equip­ment, and increases maintenance cost. Open cast min­ing technique creates more emi ss ion of fu gitive dust, which compri ses tiny partic les in chemica ll y and bio­logically more tox ic than their parent coal lump. Respi­rable and non-respirable du t impairs lung functions caus­ing "black lung di sease" bes ides silicos is, pneumoco­ni osis, and bronchiti s. Coal mine dusts also contain si I ica and naphthalene and about thirteen polynuclear aromatic hydrocarbon which are tested carcinogens 111

• The large­scale mechanized open cast mining has increased the concentration of SPM in and arou nd mining site.

A study 11.12 on open cast coa l mining reports that about

50 per cent of the total coa l dust is lost while the dum p­ers move on unpaved haul roads and 25 per cent for both during loading and unloading of dumpers. Atmospheric particles have a direct impact on climate13

. As the world stati stics has shown that open cast mining methods are the easiest, quickest and cost- effecti ve and safe for in­creasing mineral output1

\ it is needed to study the emi s­sion factors of different open cast mining operati ons. Thi s important study would help to understand the dis­persion pattern to prevent the consequences of environ­mental damage.

Materials and Methods

Study Sites Belpaher open cast mining area of Ib valley coal fi eld

of Ori ssa state in India has been selected for the present stud y. It is operatin g unde r Mahanacli Coalfil ecl Ltci .(MCL). The area which will be affec ted during project implementation. Espec ially area that will be un­der progress for mining activities in the coming 5 y and the area to be occupied indicates in the locati on map, as shown in Figure I .

Min ing Operations Several mining acti vities are considered to study the

emi ss ion fac tor in open cast mining. These acti viti es may be categori zed as point, line, and area sources. The mi n­ing operations like drilling, overburden loading and un­load ing, coal handling and the sources like haul and trans­port roads, exposed pit surface and overburden clumps, stock yard and workshop are considered fo r the present study. The point source of bla ·ting operations has not

LEGE NO

•

Area vvhleh wW be affected by mHng during proJect 1mp:emertatlon

1111 Area inclcfics the progress of mnng ectlvilies h Rll the five years folow~ng project comP,etion

[ill] Land to be possessed

Figure I -Showing the location of Belphar mining area in­cl uding the area which will be affec ted during the project area expec ted to be covered in the following 5 y and the land to be possessed under the project

been taken into account, as it is an instantaneous source.

Sampling Procedure and Analysis The standard high volume air sampler was used for

monitoring TSPM with RPM measurement unit and SO and NOx with gaseous sampling arrangement. The ave r~ age flow rate was between 1.1 m·1/min and 1.3m1/min during the sampling at proposed monitoring stati ons. The air samplers were kept at a height of 6 m above the ground level to avoid the dust from ground source. According to US EPA guidelines, 24 h sampling was clone for TSPM in 8 h interval to replace filter paper with gasseous sam­pling unit fo r sampling S0

2 and o .. The samples of

TS PM were collected by using WHATMAN GFA glass microfi bre filter papers and analyzed grav imetricall y. The samples of S0

2 and NO, were observed using so­

dium tetrachloromercurate and sodium hydrox ide solu­tion, respecti vely, and analyzed calorimetrical ly by us-

418 J SCIIND RES VOL 60 MAY 200 1

ing spectrophotometer, according to the standard meth­ods'5.lo.

Climate and Its Stability Class Micro-meteorological parameters like wind speed,

wind direction, atmospheric temperature, and humidity were studied during winter season to determine the sta­bility class of the climate in the study area. The stability c lass of a particular climate he lps in comput ing the ver­tical and horizontal dispersion coefficients of the dis­persion phenomena, while the pollutant species were

transported in the atmosphere.

Computation of Emission Rate The emission rates of different mining activities have

been calculated on the basis of modified Pasquill and Gifford formula for ground level sources. The formula

is as given in Eq. ( I ):

Cx,o = Q I 1t! .. W a? y -

.. ( I )

where C refers to difference between the downwind x,o

and upwind concentrations of the po llutant species (g/ m3 ), Q is emi ss ion rate of the pollutant species (g/s), u is avera

0oe wind speed, is (m/s), and a and a are the hori-

Y ' zontal and vertical dispers ion coefficients, compiled in functions of downwind di stance x(m), respec ti ve ly.

Results and Discussion The results reveal that the acti vities like drilling, load­

ing, and unloading of over burden dump materi als and the sources like haul roads and transport roads dust emi s­sion are contributing to the SPM concentrati on s ignifi ­cantly among all activities of open cast mining. It is a lso conc lude from the study that vehicular traffic on haul road of mechanized open cast mines are the most pro­li fic source of fugitive dust and contributes up to 80 per cent of the dust emitted from a surface coal mine 17

. The percentages of emission rates due to Haul road and Trans­port road are 30.9 per cent and 29.0 per cent, i.e, equal to 1.2249 g/s and 1. 1500 g/s, respectively. The total emi ssion rates due to the complete mining activities are 25.7 I 17 g/s. The emi ss ion rate of SPM due to various mininas are shown in Table I . The emission rates of SO,

b -

and NO due to the whole mining act ivities are li sted in X

Tab le 2. The percentages of emiss ion rates of differ nt coal mining operations are shown in Figure 2. The emis­s ion rates of the parameters like S02 and NO, are not shown for different operations because the emiss ion from

Table 1- SPM emission rate of different min ing operations

Mining operations. Drilling Overburden loading Overburden unloading Coal loading Coal Unloading Hau l road Transport road Exposed OB dump Stock yard Workshop Exposed pit surface Coal handling pl anl(CHP)

Emission rate. 0.4910 g/s 0 .5 176 g/s 0 .5617 g/s 0.0090 g/s 0 .0115 g/s

1.2249 g/s/m I . 1500 g/s/m

0.0000393 g/s/m2

0.000 1869 g/s/m2

0.000428 g/s/m1

0.0000628 g/s/m2

0.0000160 g/s/m2

Table 2- SPM , S01

and NO, emission rate for whole mine

Parameter Suspended Particu late Matter(SPM)

Emiss ion rate 25.71 17 g/s/

0.781 3 g/s 1.2785 g/s

these pollutants is neglig ible. Therefore the em iss ion rates for the parameters S0

2 and NO, for a whole mine

have been computed. The percentages of SPM, S02 and NO em is ion rates for the whole mine are shown in Fig-

x

ure3. The percentage of SPM is 92.6 per cent wh ich is equal to 25.7 I 17 g/s, whereas the percentages of S02

and NO, emiss ion rates are 4.6 per cent and 2.8 per cent, which equal to 1.2785 g/s and 0 .7813 g/s, respect ive ly. Moreover the average concentration of ox ides of nitro­gen and sulphur dioxide are found to be neglig ible.

Conclusions On the basis of the results of the study conducted in

and around the Belpahar open cast project, the follow­ing suggestions are g iven.

(i) SPM is the major source of po lluti on in and around the Be lpahar open cast project. The haul roads and the transport roads are the sign ificant sources among all other sources like OB unloading, OB loading, drilling, coa l load ing, coal unloadi ng, exposed OB dumps, stock yard , workshop, exposed pit surface

and coal hand ling activities. It is necessary to sprinkle water along the haul roads and transport roads of the mining area to suppress the particul ate mailers of the aerodynamic d iam less than I 0 ~l.

BA ERJEE eta/.: SPM - THE MAJOR POLLUTION I OPEN CAST MINI G 419

J1Road :0.9%

OBUnloading 14.2%

\ OB load01g

13J)ll

I D-ilng 12.4%

/

_ OUlers (Coal Loading

\

O.S% Coal Unload1ng Exposed OB Dump Stock Yan:l Vl/or1<shop Exposed Pi! Surtace Coal Handling J

Transport 29.0%

Figure 2 - Emission rate of SPM from vari ous operation of open cast mining like drilling, overburden loading, overburden un­loading, coal loading, coal unloading, haul road, transport road , exposed overburden dump , stockyard, workshop, exposed pit surface and coal handling plant. The figures arc shown in per­centage

(ii ) It is recommended that the loaded dump materia ls or the coals should be packed properly and made more compact using bigger size material on the top to arrest the fine particles so that the wind may not inter inside and take them away to atmosphere.

(iii) Certain evergreen plants, grasses and epiphytes like orchids could control the concentration of SPM. A study has reported that certain plants have remark­able dust filtering, air cleaning, and air purifying capacities. The plants with simple leaves such as Peepal(Ficus benghaiensis), Mast (Polualthia ), Mango (Mangifer!l_indica), Teak (Tectona grand is), Sal (Shorea robust(J.), Arjuna (Terminalis arjuna ),

etc. are better dust collectors than the plants with compound leaves like gulmohar, tamarind, cassia distula, and neem 1x.

(iv) The plantation of local species over the peripheral area of proposed overburden dump disposal site should be done, before the commencement of the project, to control the dust emission during unl oad­ing of the dump materials.

Acknowledgement The authors are thankful to Dr C Banbyopadhyay,

Scientist 'G' and Coordinator, Environmental Manage­ment Group, Central Mining Research Institute, Dhanbad for his valuable suggestions and encouragement during this study.

! •.

Figure 3- Showing the per cent age of total emission rate of SPM , NO,, abel S0

1 from various operation of open cast mining

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