Air Pollution Due to Opencast Coal Mining and It's Control in Indian Context M K Ghose • and S R Maj Ee Centre of Mining Environment
Jou rn al of Scientific & Industrial Research Vol. 60, October 200 I, pp 786-797
Air Pollution due to Opencast Coal Mining and It's Control in Indian Context M K Ghose • and S R Maj ee Centre of Mining Environment. In dian School of Mines, Dhanb ad 826004, India
Received: 29 Janu ary 200 I; accept ed : 29 June 200 I
Open cast mining dominates th e coal production scenario in India. It creates more serious air pollution prob le m in the area. Coal producti on scenari o and its impact on air quality is descri bed. To maint ain th e energy demand in opencast min ing i~ growing at a phenomenon rate. There is no wcll-clefinccl method for assess in g the impact on air qu alit y clu e to minin g projects. An investi gati on is condu cted to evalu ate th e impact on ai r enviro nment due to opcncast coal mining. Emi ssion fac tor dat a arc utili zed for computati on of du st ge neration due to different mining ac ti viti es. Approach for the selec ti on of work zo ne and ambient air monitoring stations arc cl cscribccl. Work zone air qu alit y, ambient air qu alit y, and seasonal va riati ons arc di sc ussed. whi ch shows hi gh po llution potential clue to SPM. The statu s of air pollution clue to opencast mining is evaluated and its impac t on air environment is assessed. Characteristics SPM show a great concern to human hea lth . Air pollu tio n control measures involve pl anning and implementati on of a series of preventi ve and suppressive measures in addi ti on to du st ex trac tion system. The study reveals that th ere is a need for wider appli ca ti on of du st co ntrol chemi ca ls and an in depth techno-economic survey i ~ essential. Different abatement measures for co nt ro l of air pollution arc enumerated . Air pollution cont rol by trees. rrees tolerant to dillerent ai r pollutants and pl ant species useful for co ntrolling air polluti on is di sc ussed. The meth odology adopted could be utili zed on industrial sca le for various sites.
Introduction coal production was 75 Mt/y the share of opencast mining was 20 per cent. By 2000 AD when the total coal Coal is the primary source of energy'. The develop producti on was 4 17Mt th e sha re by opencast mining ment of various industri es has a cascad ing affect on th e reached about 70 per cent and th e future plan envisages demand of coal. With the rapid rate of growth of larger share by opencast mining. industries, the future demand of coal will be very hi gh.2 But th e utili zation of coal would be limited by In opencast mining, a mass ive overburden will ha ve environmental di sruption, including deteri oration of air to be removed to reach the mineral deposits. Thi s may quality due to the emission of particulate matter and other require excavators, transporters, loaders, conveyer belts, gaseous pollutants from various mining operati ons , etc., which will results in massive discharge of fin e wh ich , in general , have adverse environ mental impacts . particulate from th e overburden materials. Similarly The magnitude and significance of air pollution, caused normal operations will a lso require excavati on, by mining, depends on method of mining, sca le and transportation, loading, unl oading, size reduction, stock 4 conc entration of mining activities, geolog ical and piling etc . All of th ese will generate particul ate geomorphological setting of th e area. In India, coal matter ' · The volume and variety of air borne du st production will have to be increased to meet the energy particles in the ambient air is ever increasin g and causing demand at the rate of 20-25 Mt/y (ref 3). In underground air pollution problem in th e surrounding areas. Cowherd r' coal mining humans suffer from coal mining inside has reported that vehicul ar traffic on haul road of underground workings but opencast mining creates much mechanized opencast mines can contribute as mu ch as more air quality deterioration in res pect of dust and 80 per cent of the du st emitted. Chadwick et of. 7 ha ve gaseous pollutants in and around th e mining complexes. estimated that about 50 per cent of total coal dust released Opencast mining dominates the coal producti on scenario during journey time on an unpaved haul road, while 25 in India due to the techno-economi c factor, better safety, per cent for both during loading and unl oading of dumper. etc. At the time of nationali zation in 1973, when th e total Drilling is perhaps th e next important source of fu giti ve dust K. Another major source of fugi tive dust is wind · Auti1or for corresponclcn cc eros ion from coal stockpiles. GHOSE & MAJEE: AIR POLLUTION DUE TO OPEN CAST M INING 787
13 O ver e xpl o ita ti o n o f na ture in th e na me o f Control Board (CPCB) , Governme nt of India. T he industri alizati on and development is causing degradati on sampling was continued twice a week for four weeks in of our environment. At the same time, we do relali se a month of each season covering winte r (January), that we cannot stop the development in the name of summe r (M ay-June), monsoon (August) and post 14 saving environment onl y. A balance between sustainable mo nsoon (O c tobe r) seasons. · Air samples were development and environment management is the need coll ected for 24h in three 8h shi fts correspond ing to of the hour. E nvironmental impact assessment (EIA) daytime, evening, and ni ghttime. Micrometeorological 1 pl ays a crucial role in resolvin g the conflicts' . Thus, it is data were coll ected on sampling days with respect to necessary to assess the impacts on air environment due w ind directi o n, w ind veloc it y, humidity a nd 15 to ope ncast coal mining so th at prope r me ti gati ve temperature. · "'. SODAR data were coll ected from a measures could be implemented . However there is no monostati c and Doppler SODAR make M/s Ramtech, well-defined method of assessing the impacts on air France in stall ed at Central Mining Research Station environment due to opencast coal projects. To evalu ate (CMRI), Dhanbad . The parameters studied were wi nd the impact on air environment a fact-finding survey is speed and direction, mi xing height, ventilati on coefficient essentia l. In this study atte mpts have been made to (VC). develop a methodology to evaluate the statu s of air For the coll ecti on of samples of suspended parti culate pollution due to opencast coal mining and to suggest matter (SPM), glass fibre ambient (GF/ A) filter paper control measures for the control of air pollution. was used in a hi gh volume sample r (HYS) and fo r Materials and Methods respirabl e dust parti culate matter (RPM) GF/ A was used T he study area was one of the largest opencast coal in respirable dust sampler (RDS) at a flow rate of 1. 1 to projects (OCP) fo r coking coal in Jhari a Coalfields (JCF). 1.5 m'/min that all ows th e SPM to deposit on the filter It has 34.6 Mt quarri able reserve of coal. T he project paper. Particul ate with size range of 0. 1 to I 0011 m was 17 coll ected by HYS . The cut-point diam of RDS was less report was sanctioned in the year 1982 for a targeted production of 2.5 Mt/y and the li fe of the project was th an I 011 m. Both, HVS and RDS were manu factured by M/s Envirotech Ltd, New Delhi . HYS, havin g impi ngers 17 y. The quarry was bein g worked in two patc hes (bubbl e r tra in s) in seri es w ith sodium th rough separate box cuts. Working depth during th e study peri od was about 60 m in box cut three secti ons. tetrachl oromercurate as absorb in g solutio n, were operated at a n average fl ow rate of 0.5L /m in fo r Working was goin g on in X seams havin g seam thi ckness coll ecti on of SO (as per IS: 5 182, Patt II 1969) fo r 24h.fn of 9.62 m. The project is located in the north-west of JCF in Dhanbad di strict of Jharkhand State. It covers an the case of coll etti on of NO sodium hydroxid e was used as absorbing soluti on and coll ected at an average flow area of about 6.8 sq km It is located between latitudes rate of 0.5L /min fo r 24h (as per IS: 5 182, Part IV 1976). 23°46'30"N and 23°47'4"N and longitudes 86° 10'47"E The impinger samples were put in ice boxes immediately and 86° 13 '3 1"E . It is surrounded by many open cast and after sampling and transferred to a refri gerator pri or to underground coal mines. a na lyse. The samples were a na lysed spectra Work zone a ir qua lity monitoring stati ons we re photometrically. usin g West a nd Gake methods and 111 selected near the sources of air pollution • T he detail s Jackob and Hocheiser modi fied meth ods for analysis of of the monitoring stati ons are given in Tabl e I and 2. SO and Nox, respectively 17 S PM a nd RPM were Ambient air monitoring stations were selected, keeping co~p ut ed after weighing the fi lter paper before and after in view the domin ant wind directions prevailing in th e samp lin g. T he fi lter paper was conditi oned in a dry area. One ambi ent air monitoring station was located in atmosphere before weighing. the project office of OCP. T he dominant win ds directions of th e area"·" were Wand NW. During the selecti on of Parti cle size analysis of SPM was done on the basis ambient air monitorin g stati ons the approach was to put of the principle of photo-extinction and sedimentation two monitoring instruments at upwind (W and NW ) and techniques w ith a M icron Photosizer manufactured by two instruments at downwind (E and SE) di recti ons. The Seisin Enterprise Co. Ltd, Japan (Model S KN I 000). approach was also to see th at these shoul d cover the Attachment of centri fuge with th e uni t had made it pos industrial, residenti al and sensiti ve area li ke hospital as sible to determine size d istri bution up to 0 .02 p. Respi diffe rent standards have been laid by Central Pollution rable dust sampler (RDS) make Envirotcch, New Delhi 788 J SCIIND RES VOL 60 OCTOBER 200 1
Tab le !- Location of work zo ne monitoring stations
Sl No. Station site Location
BW I Feeder breaker Roo f of feeder brea ker control room at abou t 3m abo ve the ground
BW2 Haul road (HR I ) At a height of about 2m on the debris at one side of th e haul road
BW3 Haul road near box cut On the other of hau l roa rd near near th e hox cut 3 office
3 section (HR2) at about 3 m above the ground
BW4 Dragline secti on At a di stance of I OOm from the draglinne at about 2m above th e gro und
BWS Shovel/dumper loading On the immed iate above the bench of a working bench
BW6 Workshop Roo f top of a room ncar th e workshop area whi ch is abo ut 3m above
the ground
Tab le 2-Locati ons of different ambient air monitoring stations
Stn No. Sta tion si te Nature of area Directi on from Locati on Block II OCP
BAI Block II OCP Industrial Centre On the roof top of the Block II pi t oiTice wh ich abou t 4m above the ground level
BA2 Benidih OCP Indust ri al E On th e roof top of th e su rvey office at survey offi ce about 4m above the ground
13A3 Nudkhurkee Res identi al w On th e roof top of a vi llager 's hou se which abo ut 7m abo ve the ground
BA4 M adhuband Residential SE On the roo f top of a villager's house ;ll about 3m above the ground
BAS Benidih hospital Sens itive NW On th e roof top of the hos pital at about 4m above the ground was used to determine respirable particul ate matter were utilized fo r assessin g dust ge nerati on clu e to 1 20 (RPM). In RDS , th e du st-laden air is imparted with a different mining activiti es x. . It has been estimated that rotating motion by virtue of its tangential entry into th e different mining acti viti es generate dust, wh ic h 21 cyclone. Due to thi s rotati on, dust particles > I 0 1J de accounted 9 .36t clu st/d • The dust generated by eli fferen t posit on the wa ll s of th e cyclone and settl e be low and activities contributes SPM as we ll as sett leabl e fracti ons the air containing the RPM travels up and is co ll ec ted in the surrounding locations. over GF/ A fi lter paper. Cascade impactor was also used The data of four seasons revealed that SPM for particle size analys is (make Graseby, Anderson, UK). concentrati on fo r almost all th e mon it oring stati ons exceeded the permi ss ibl e limit spec ifi ed by Central Assessment of Impact on Air Environment Polluti on Control Boa rd (CPCB) (Table 3) during winter, The sources of ai r pollutants were identified and pre-monsoon and post-monsoon periods. During th e different mining activ iti es were record ed along with monsoon peri od, SPM fe ll withi n th e permi ss ible limit producti on of coal and overburden materials. During the due to the removal of du st particulate with rain water. In study peri od the mine was prod ucin g 2500 t coa l /d and fact, they exceeded the permissibl e li mits specifi ed fo r 3 3 1 overburden removal was 9950 m /d. Em iss ion fa ctor data industrial (500 pg/m ), resid ential (200 pg/m ) and GHOSE & MAJEE: AIR POLLUTION DUE TO OPEN CAST M INING 789
Table 3-Nati o nal ambient air quality standards (Central Pollution Control Board, New Delhi)
Po llutant Time Concentratio n in ambient air weighted average Sensitive Industrial Residential , Methods of measurement Rural Sulphur Annual* 15pg/rn' 80pg/m3 60pg/m3 !.Improved West and Gake method 3 .\ 3 dioxide (S02 ) 24 h** 30p g/m 120pg/m 80pg/m 2.Uitra lluorescence Oxides of Annual* 15pg/m' 80pg/m3 60pg/m3 I Jacob and Hocheiser modified nitrogen as 24 h** 30pgtm·' 120pg/m3 80pgfm3 method N02 2 Gas phase chemilluminesencc Suspend ed Annual* 70pg/rn3 360pg/m3 140pg/rn 3 - Hi gh volume sampling particul ate 24 h** I 00pg/rn1 500pg/rn3 200pg/rn3 matter (SPM) Respirable Annual* 50pg/rn.1 120p g/rn.1 60pg/rn3 - Respirable particulate matter particulate 24 h** 75pg/m. 1 150pg/m.1 100pg/m3 sampler matter (RPM) 3 1 3 Lead (Pb) Annual* 0.50pg/m I .O p g/m 0 .75p g/m - AAS method after sampling using 24 h** 0 .75pg/m·' 1.5pglm3 I.Opg/m3 EPM 2000 Carbo n 8 h** I.Omg/rn3 5.0mg/m3 0.50pg/rn1 - Non-dispersive infrared monox ide (CO) I h 2.0mg/nr' I O.Omg/m .1 0.75pg/m3 spectroscopy *A nnual arithmetic mean of minimum I 04 measurements in a year taken twice a week 24 hat uniform interval **24 h /8 h values should be met 98 per cent of the time in a year. However, 2 per cent of the time. it may exceed but not two consecuti ve days
3 hospital ( I 00 f.lg/m ) areas. During winter, pre-monsoon suppressive measures so th at the levels of pollution are 11 and post-monsoon periods RPM concentration in the maintained within certain standard . For thi s an air industrial location (BA I) also exceeds the permissible po llution strategy is formu lated wh ich refers to the master 3 limit ( 150 f.lg/m ). SO and NOx concentration were also plan adopted to tackle the air pollution Y Four types of found to exceed th ~ permissible limit at different strategy have been distinguished for air po llu tion control. occasiOns. These are: Seasonal variation of SPM in work zone air is shown (i) Air quality management, in Figure I. Work zone air quality to be deteriorated during winter season to great extent. SPM and RPM (ii) Emission standards, concentrations were found to be very hi gh and exceeded (iii) Economic, and the permissible limits at all locations. Seasonal va ri ation of SPM in ambient air at different stations is shown in (iv) Cost benefit. Figure 2 and status of air pollution in the study area is shown in Figure 3. The data of four seasons revealed Air quality management is th e regul ation of the that SPM concentration for alm ost all stations exceeded amount, location, and time of pollutant emi ss ions to the permissible limit specified by CPCB. Settleable dust achieve some clearly defined set of ambient air quality observed at different locations also exceeded the standards. It involves the control of pollutant emissions permi ssible limit ( I 0 mt/km2/month). The wind rose to ensure that these levels do not exceed th e acceptable diagrams at different seasons are shown in Figure 4. limit. It in volves several steps, whi ch are discussed within Characteri stics of SPM showed th e hi gh concentration a five-fold typology (Figure 6). Em iss ion standards are of respirable fraction , Average particle size distribution di stinguished for large number of pollutants and are of SPM in work zone and ambient air are shown in app li ed to individual or specific group of emitters. If Figure 5. emission standards are derived from consideration of air quality standards, this makes th e emission strategy, in fact, a part of an air quality manage ment strategy. It is Air Pollution Control Strategy also known as "best ava il ab le and economi cally feasible The air pollution control measures in vo lve planning control technol ogy". Such an approach could reduce air and implementation of a series of preventive and po lluti on up to great extent with known methods but th ese 790 J SCI IND RES VOL 60 OCTOBER 200 1
1.000
'E....._ 01 _:. 3000 c 0 Iii -E 2000 Winter Summer Mo nsoon P-monsoon UliiiD BW1 I FBI ~ BW2 I HR 1 l Clli] BWJ IHR2l ~ BW 4 IDSI D sw s I SO LI LJ BW6 IWSPI Figure 1- Seassunal variation or SPM in work zo ne air 1000,---- BOO • BA1 ~ BA2 f§l BAJ ffiiiill BA' CJ BA6 Figure 2-Seasonal variatio n or SPM in ambient air at different stations should be economi ca l. Strategies, using an economi c If polluti on control expenditure is not made, ambi ent air based approach to air polluti on control wo uld prov ide pollution concentrati on will be hi g h and pollu tion fin ancial incenti ves fo r emi ss ion sources to pursue the da mage cost will also go up. As control ex penditure mos t cost-effec ti ve means fo r reducin g po ll uti on. The increases, th e po ll uti on concentrati on and associated emiss ion charges strategy, based on requ iring polluters damage costs fa ll. to pay charges relatin g to the amount of po llu tion they emit are most frequentl y used. The purpose is to leave to Strotegy Adopted the choice of polluters not to pollute or to pay fine heav il y with penalties increasing ex ponentiall y with the degree As th e project area inclu des the opencast mine, for of poll ut ion. Economi c approach to prov ide in centives whi ch no emi ss ion stand ard s have been proposed and to a fim1 to fin d new tec hni ques and new products, which no economi c strategies have been devel oped, so th at the provides lower po llutant emi ss ions. Cost benefit strategy strategy ad opted here should be th e combinatio n of the first attempts to quant ify th e costs of all the damage air quality managemen t and cost benefit strategy. On the res ul tin g from air po llu ta nts and the cost of all known basis of coll ected field data it has been observed that th e ways of controll ing these po llu ta nts and then adopt th e ma in po llu tion proble m in th e area is due to the du st. A pollution control options whi ch will minim izes th e scene contro l plan has been fo rmulated for abatement of air of po llu tion damages and pollution control costs. In po lluti on probl e m. It in vo lves th e planni ng and Figure 7. conceptual approach of this form is ill ustrated. imp lementation of a series of prcventi ve and suppressi vc GHOSE & MAJEE: AIR POLLUTION DUE TO OPEN CAST MINING 79 1 500 120 500 100 ,., ,., ..._E E §r L.OO --§r BO c 350 .!: c c .2 .2 100 20 70 BA1 BA2 BA3 BA4 BAS 100 100 BO ,., 0 ,., E E ..._ -..... Dl 0'1 :::l. :::l. c .!; 60 c 60 c .2 .2 ..... ~ ~ c c QJ BA1 BA2 BA3 BA 4 BA s E'3 BAL. D BAs Fi gure 3-Status of air pollution in the project area (Annual average concentration o f air pollu tant s under study) 792 1 SCI !ND RES VOL 60 OCTOBER 200 1 SUMMER SEASON WINTER SEASON N N w w ~t===r-----( SE SE s SW s Nw'T-MONSOON SEASON MONSOON SEASON N NW w w sw SE s Seal<.> :- 1 em = 5 '/, ~ 1 7 14 28 Km/hr Figure 4--Wind rose diagram during differelll seasons measures, in addition to the dust extraction syste m 1 ~. 100r-~ Dust Extraction System The dust extraction system envisages wet type dust extractors. This includes network of suction heads and ducting connected to wet wall cyclone for separating dust from the air stream. Air outlet of cyclone collectors will have to be connected, so as to discharge clean air to atmosphere and collected dust from the cyclone shall have to be disposed off suitably. It includes the following: (i) Wet Wall Cyclone Separators 20~ ~ ---'--- '~ J The wet wall cyclone separators must include its all s 10 20 1.0 60 eo 100 required accessories like water spray nozzles, headers, Particle size (IJ) water piping hydraulic scales, solenoid valves, and - Wo rk zone -1- Ambi ent ton e- isolating valves to ensure sufficient separation of coal Figure 5-Average particle size di stributi on o r SPM in ambient and dust from dust laden air. work zone air GHOSE & MAJEE: A IR POLLUTION DUE TO OPEN CAST MINING 793 SPECIF Y AI R QUALIT Y COMPI LE AN MONIT OR MO NIT OR STANDARD S INVENT ORY OF METE OROLOGICAL AIR POL LUTION OR GOAL S SO URCE EMISSIONS CONDITIONS CONC ENT RATION I I J l APPLY MODEL TO J CALCULATE AIR O.UAUTY DEVISE A SET OF EMISSION CONT ROL TACTIC S TO ACHIEVE AIR QUALITY STANDARDS J ENF OR SE EMISSION l CO NTROL TA CTIC S _j 1 l AIR- QUA L!TY AIR - QUALIT Y STANDARDS STANDARDS ACHIEVED NOT ACHIEVE D Figure 6-Stages involved in the ambient ai r-quality management strategy POLLUTIO N CO NTROL EXPENDITURE I OR COST l \ POLLUTION DAHAGf COS\ "'0 u TOT AL OAHAGf +C ON TR OL 1/cosT I I \ /. ' OP TI HUH / ,...... I ..... ------/ ' ____ / Ambient air pollution concentration Figure 7-Schematic repres ent ation of the rela tionship between po ll ut ion control expenditure, pollution damage cos t and polluiant co nce ntration 794 J SCIIND RES VOL 60 OCTOBER 200 1 (ii ) Air Exhaust Fan Dust Suppressive Measures Air exhaust fan should be of centrifugal type with (i) Water Spraying radial bladed impe ll er. The fan s should be of robust. The The regul ar spraying of water over coal inc reases fan associated with dust extraction should be designed the free moisture content of th e coal and also provides for adequate duty keeping of approx. 25 per cent on quantity of water needed to bind th e dust a nd to pressure rating. The fan must be vibration-free during agglomerate into a semi solid condition. operation and designed to limit noi se level to 90 elBA. The fan and motor are to be observed for continuous (ii) Water Spraying by Ultrasonk Dry Fogging System hy Means operation. Relevant IS code of engin eerin g practi ces has nf Service Nozzle to be e mployed for the desig n and construction of In this system, water droplets are set between 0.3 impe ll er, shaft and bearings. to 5.0-mm diam with th e he lp of compressed air. Wi th increasin g fineness of droplets, th e surface area affinity for dust increases, along with th e number of droplets per (iii) Dust Collection Hood unit volume. It is clu e to th e fact that th e droplets roughl y Necessary dust coll ecting hoods and MS sheet ducting havin g the same size as th at of the dust parti c les and as of adequate size and design must be provided for guiding they are charged, the affinity requ ired fo r wetting the dust laden air fro m the generating points to wet wall dust is achi eved and th e dust partic les agglomerate and cyclone separators and dust-free air from cyclo ne to suppresses at th e source. This requires no wetting agent. atmosphere via extraction fan s. The clean air from the (iii) Chemicals for Dust Control fan has to be taken to a suitable he ight (not less th an 2 m or I .5 m above height of roof in the vici nity, which ever Water sprayin g requires huge quantity of water but is more) before discharging into atmosphe re. The clue to th e scarc ity of water in most of the coal mines it fo ll owin g points should be considered while designing is required to reduce wate r consumptio n fo r dust hood and ducting system. Centre line of hoods is to be suppression. It is possible o nl y if suitable chemicals. located at the points of generati on of maximum pressure. whi ch act as wettin g agents, are added to water. It he lps The hood connecti on has to be designed for coll ecting in proper wetting of the fin er sizes of dust and increases the dusty air from various dust generation sources. The th e effic iency of wetting. hoods are to be adequately sized to coll ect all dusty air Chemicals, useful as wetting agents are the following: generated at the point. Ve locity in the hood should not be too hi gh as to draw the large size parti c le . The ducts (a) Aqueous solution of CaCI , MgCI , hydrated time, ::! ~ fo r conveyin g dusty air are to be of shoul d have round sodium sili cate. etc. , shape, havin g stream line appearance. (b) Teepol- laboratory grade product of Burmah Shell, (c) Kodak wetti ng agent - product of Kodak Ltd , (iv) Dust Arrester The dust produced duri ng drilling and blasting could (d) Lessapol - product ofT mperial Che mical Industri es, be minimized by arresting and filtering the dust-l aden (e) F il set 50 - product of F ill er Group of Company, air before it is thrown into the workin g environment. Dust arresters commonl y used w ith clown th e hole drills (f) Jalasakti - A hygroscopic soli d. at the coll ar of the holes being drilled. (iv) Haul Road Dust Consolidation (v) Dust Extractors with a Filtering or a Porous Layer Surface mine haul road is the most prolific source of The fi lterin g unit m ay be made of solid a nd 25 dust in surface mines . Watering of the haul roads is the continuous consisting of pape r, which gives a very hi gh most common method of cont roll in g dust emi ssion. The efficiency. T he filte ring layer may comprise friable frequency of watering has to be related to the c limatic materi al such as loose powde r, sand or granular material, conditi ons. Va rious products are avai lable in the market in a horizontal or verti cal bed, cotton, wool, glass c loth for consolidati on of hau l road dust as the water is quick ly with silicon and other synthetic fibres. evaporated if the water sprayin g is not done at frequent GHOSE & MAJEE: AIR POLLUTION DUE TO OPE CAST MINING 795 Table 4--Abatement measures for control of ai r pollution at the source Dust Source Control measures 2 Dust suppression by water and I or detergent 3 Use of dust arrester Blasting I Dust may be suppression by water sprays Before charging and blasting consideration of expected atmospheric condition Loading and unloading I Suppress dust by automatic or mannual water sprays (with detergent) 2 Enclose of the loading and unloading area, wherever possible Mobile equipment I Intern al roads to be surfaced 2 Exhausts fan to be directed upwards 3 Dust suppression by water sprays 4 Selection of proper routes 5 Sheeting of loads of fine materials 6 Green barrier along mine road Fixed plant (Crushers, screen conveyors. etc.) I Provision of enclosers 2 Use of water sprays to suppress dust 3 Use of dust coll ectors (bag, wet or dry centri fu gal, electrostatic, etc.) 4 Green barrier all around Dust blow I Enclosure of stock piles 2 Vegetation of waste dumps 3 Water spraying to suppress dust 4 Establishment of green barriers of trees intervals. The raised dust causes the problem of visibility Air Pollution Control by Trees on the haul road, which, in turn, affects the average Plantation of trees is one of the best measures for vehicle speed in addition to the pollution problem. The checking the air pollution. Trees are to be selected, based health of the workers would be affected due to high on the type of pollutants, their intensity, location, easy respirable dust concentration. Various products are avail abi lity and sustainability to the climate. For arresting available in the market for the consolidation of haul road dust pollution, trees having compact branching, closely dust. Hygroscopic salts extract moisture from the arranged leaves, broad leaves of simple elliptical and atmosphere and keep the road surface damp. Most hairy structure, shiny or waxy leaves and high proline common examples are calcium chloride, sodium si li cate, content are suitable. A list of trees tolerant to different magnesium chloride, and hydrated lime. Surfactants/ air pollutants is given in Table 5 wetting agents could reduce the surface tension of water helping wetting of dust particles and thus economize the A wide green belt of fast growing trees should be watering costs. Monitoring of SPM was done with the raised around the coal project. New colonies and help of high volume air samplers. SPM was measured residential building should be created at a considerable before and after application of the chemical (Filset-50) distance from the project. To create green barrier around and found that SPM level of 263 I 11g/m3 came down to roadsides, fixed plants, stockpiles of OB dumps the about 780 11g/m3 after one month of application. The following guidelines may be useful in increasing the study reveals that there is a need for wider application efficiency: of dust control chemicals on the haul roads of Indian (i) Trees s hould be planted in beds arranged coal mines. perpendicular to the direction of prevailing wind, Control of Air Pollution (ii) Trees should be planted in a concentric fashion around the source of pollution, Different abatement measures for control of dust (iii ) Peripheral plantations may also be used as wind generated from different mining operations are given in brakes on dry tailings, Table 4. 7% .I SCI IND RES VOL 60 OCTOBER 200 1 21 (iv) A judicious mixture of open and permea bl e planting Maiti and Banerj ee ' have found that the plants can with dense planting should be made to achieve act as li vi ng filters of dust polluting in mining areas. It is max imum beneficial effect, reported th at a 8 m wide green belt between roads and buildings can red uce the dust fall by 2-J times coni fe r (v) Plant s and trees of different heights should be reduce dust fa ll up to 42 per cent in te mperate urban planted on both sides of the traffic lanes, areas. The stud y indicates th ese evergreen plants with (v i) A wide green belt of I 0-m width with 6 rows of tall simpl e, pol ish surface lik e -Alstonia scholaris, Ficus fast growing trees will have to be rai sed around the lun ea, F. henghalensis and Mognifem indica are best CHP and mine complex. dust catchers. Plant species useful for cont ro lli ng air pollution are given in Tabl e 6. Table 5-Trees tol erant to air pollutant s Conclusions Dust pol luti on Sulphur dioxide Ma in air po lluti on problem due to opencast mining is Alswnia scholoris Alhi:ialehheck cl ue to the du st. Work zone and ambient ai r quality data Cassia sia111ea A ilw111111s e.rcd1·11 also reveal the hi gh pollution potenti al in the project area Dalbe1gia sissoo Alstonia sclwlaris and surrounding locations. The respirable frac ti on in Ficus henghalensis A:adimchw indica SPM is fou ncl to be hi gh and alarming to human health. Air pollution control measures involve planning and F. in{t'c/oria Fims religiosa implementation of a series of preventi ve and suppression i\1/angifi'm indiu 1 Lagestm<'lllia measures in add iti on to dust extraction system. There is Pt'lloii!IOrtllll feiTI I.f!.ill l'l /111 MiiiiiiSOIIS clw1gi a need for wider app li cation of dust control chemi ca ls on haul roads for whi ch an in depth techn oeconomic Polwt!thia lognifl'lia Polmlthia lognift'm survey is essent ial. By proper imple mentati on of Shm•ea rolmsta Tl'llrinalia m:jw w suggested abatement measures, ai r pollu tion in opencast A en f'latanoides mi ne and its envi ronment can be suitably controll ed and 'l i'clontl gmndis Quacus fWiustri.l· also a ri g ht kind of ba lance between sustainable development and environmental manage ment can be Alnus l' iridis Q. mhra mai ntained . The methodology adopted rnay have formed OI.O ne Oxides or nitrogen guid elines wh ich could be utili zed on in dustrial sc al e Accr Ncgunda Cagus orit'lllalis fo r various sit es Accr Plwllanoides Quercus m hmr Acknowledgements Quercus palustris Nohinia f!Sellllocacia The authors are th ankful to the Ministry of Aar J!Iatanoides Lead Env ironmental and Forests, Government of India for A. negunda Cassia silllllt'S financial grants for infrastructral facili ties at Centre of Qut' IY" IIS palustris Zi~.1p l111s n1 t1 11ritiww Mining Environ ment, Indian School of Mines. Financial Table 6 -Useful plant spcci(;s rnr controll in g :~ ir polluti on along with th eir ch:1rac teristics Speci:t l properties NdlllC or species (i) Puhe~ce nc e on leaves t0 entrap : Cua:ama, Putrwrjil'£1, N1·ctantlll's, Trenw , llolof!i'leliu. Tem1inalia and hold dust panicle' (i i) Leaves and branches to slow winll. Alhi::ia. Smnania, PellmJJiw mlll. h1111arindus /)ei!Jagio (iii ) Blossoms and foliage that prmidc Morinda. Cl'sllwn. Locntmw, Anona, /11iclll'litl, .laslllillltll l (itm s, plca~a n t smell to mask: ndnur. Plu1ncritt, !11o gnoliu. (il) Lca1·cs and br;111chc' to slow the act1on of r;Jill \: A:an!ichw. Nelia. Acacia a,, ,·icn!twfrnmis. /)c/oni.r Ca.Hw (v) Plants th;ll absorb SO Lir·lll't ts. Fagus, Acer GHOSE & MAJEE: AIR POLLUTION DUE TO OPEN CAST MINING 797 support in th e form fe llowship receiv ed from th e I :l Banerjee S K.. 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