Mrinal K. Ghose

Assessment of Dust Generation Due to Opencast Coal Mining– An Indian Case Study

Every mine in India has to obtain environmental clearance fromthe Govt. Air pollution is one of the most important parametersto be considered in preparing an EIA. However, there is no welldefined method for predicting thr air pollution impact due tomining. Increasing trend of opencast (O/C) mining leads toproduction of huge quantities of dust. Emission factor data havebeen utilised to quantify the generation of dust. The projectunder study is one of the largest opencast project (OCP) forcoking coal. The main sources of air pollution have beenidentified. The rate of emission per unit of a given activityknown as an emission factor has been utilised, taking localfactors into account. It has been estimated that due to topsoilremoval, overburden (O/B) removal, extraction of coal, sizereduction generated 7.8 t of dust per day. Wind erosiongenerated 1.6 t of dust per day and the whole operationproduced dust which accounted for 9.4 mt/day. They cause airpollution in the work zone and surrouding locations. Themethodology adopted may be used to quantify generation for otherprojects also.

Status of air pollution caused by coal washery projects in India.

The importance of coal washeries in India is growing as local coals have a high ash content. At present, there are 23 coal washeries with an annual rated input of 45 Million Tonnes. During the various operations in washeries, large amounts of dusts and gaseous pollutants are generated. Four coal washery projects were surveyed to study their air pollution characteristics. Air monitoring stations were set up in local industrial, residential and sensitive areas and air pollution samples were collected along with micro-meteorological data. Diurnal variations of SPM, SO2 NOx and CO are discussed. SPM concentrations were found to exceed the permissible limits at all locations. SO2 and NOx were also found to exceed the permissible limit in residential and sensitive areas. It was observed that about 50% of the dust particles were less than 10 µ in diameter. Benzene soluble matter in SPM ranged from 45–62%.

Characteristics of iron ore tailing slime in India and its test for required pond size.

The physical and chemical nature of the tailingslime depends on milling operations and water contentin the effluent. The characteristics of the tailingsdictate the type of disposal facility required.Characteristics of the tailings, transportation frombeneficiation plants and disposal system are described.Studies on tailing slime have been carried out at ironore mines in Orissa and the results are discussed. Thetailings contain toxic elements and find their wayinto the water environment. Sedimentation test was carriedout on tailings and the area required for tailing pondwas found to be 3155 m2 in comparison to10 000 m2 obtained from the use of an empiricalequation. Provision of tailing pond for the disposalof tailings is a conservation of resources in additionto pollution control, and sedimentation test is essentialfor required pond size calculation.

Air Pollution Due to Opencast Coal Mining and the Characteristics of Air-Borne Dust--An Indian Scenario

Opencast coal mining creates more air pollution problem in respect of dust and the fines contain coal particles, benzene soluble matters etc. To maintain the energy demand, opencast mining has been growing at a phenemenon rate in India. There is no well defined method for assessing the impacts on air quality due to mining projects. An investigation was conducted to evaluate the impacts on air quality and the characteristics of the air-borne dust due to opencast coal mining in Indian context. The study area has been described and the sources of air pollution were identified. Methodology adopted for the selection of air monitoring stations and air pollution monitoring to evaluate the impacts on air environment due to coal mining activities have been discussed. Impacts on air quality have been assessed on the basis upwind and down wind concentrations of air pollutants. SPM and RPM concentrations were found to be very high in work zone as well as surrounding locations. The SPM was subjected to particle size analysis using different techniques. It was observed that the particulates were more respirable in nature and the median diameter was around 20 w . Variation of weight percentages for different size ranges has been discussed as a function of mining activity. Benzene soluble matters and anions in SPM were found to be high in comparison to other areas. Settleable dust and its compositions were also analysed. The methodology adopted for the study may be utilised to assess the actual contribution of air pollutants due to other coal projects.

Assessment of the Status of Work Zone Air Environment Due to Opencast Coal Mining

In India coal production will have to be increased to meat theenergy demand at a very high rate. By 2000 AD the coolproduction from opencast (O/C) mining will rise to 250 Mt. whichwill be about 70% of the total coal production. The increasing trend of O/C mining leads to cause air pollution problem. A surveywas conducted to assess the status of work zone air envirnmentdue to opencast coal mining in Jharia Coalfield. Keeping in viewof place of dust generation air quality monitoring stations wereselected. Methodology adapted for sampling and analysis of airpollutants have been described. Four season data revealed thatmaximum concentration of SPM was observed at dragline sectionand the next high concentration was at haul roads. At all thelocations SPM and RPM concentrations exceeded the permissiblelimits specified by Indian Pollution Control Board. Shift wiseand location wise analysis for getting higher concentration ofSO2 and NOx have been discussed. Wind velocity anddirections, mixing heights, ventilation coefficient of the areahave been analyzed. Huge dust generation creates vision problemto HEMM operators. The methodology adopted may be utilised onindustrial scale for various sites.

Environmental impacts of Indian small-scale mining industry - an overview

India is among the top ten mineral producing nations in the world and its economy depends on the value of minerals produced. Small-scale mining is more prevalent in India. Although mineral production has increased significantly since countrys independence, what continues to be overlooked, is the contribution of resident small-scale mines to national mineral output. Approximately 90% of Indias mines are operating on a small-scale, employing some 0.5 million people. It provides a wealth of socio-economic benefit to the rural inhabitants. However, because of their rudimentary and highly migratory nature, these operations feature poor environmental management and safety conditions. This paper examines the unique techno-economic and socio-cultural characteristics of some selected small-scale mining regions in India. It identifies the drawbacks in the existing government policy and discusses the role of government for up gradation in this sector. It also focuses the need for technical up gradation and to ensu...

Monitoring and assessment of impact on air environment caused by coke plant operations in India

Coals are converted into coke in coke plant by high temperature carbonization. Total washed coal availability in India was 11 Mt during 1995–96 against 16.2 Mt in steel plants. During various operations substantial amounts of dust along with gaseous, pollutants are released into the atmosphere, causing air pollution problems in the surrounding areas. The present investigation provides a quantitative scenario of stack emissions from a coke plant and its impact in the surrounding areas. Ambient air monitoring stations were selected at upwind and downwind locations of a coke plant. Maximum mixing height was 1200–1600m. The afternoon ventilation coefficient was 4000–6000 m2/sec. SPM concentration at all locations was found to exceed the permissible limit. The contribution of pollutants by the coke plant to air quality in the surrounding areas has been evaluated.

Deterioration of soil quality due to stockpiling in coal mining areas

In the process of opencast mining, the area is to be stripped of vegetation to remove the overburden. Several changes occur in the physical, chemical and microbiological properties of soil as a result of mining and storage. One large opencast coal project of Eastern Coalfields Ltd (ECL) was investigated to assess the deterioration in soil quality. The study reveals a major qualitative deterioration in the excavated soil when dumped over a long period of time. This inability to preserve topsoil is one of the basic hindrances to restoration of mined land and overburden dumps. Hence the topsoil should be stockpiled only when it is impractical to redistribute promptly over the affected areas.

UNDERGROUND COAL GASIFICATION: A NEGLECTED OPTION

The energy sector is crucial to development. Coal is the prime energy resource in the foreseeable future. There is urgent need to develop alternative energy sources, which are cleaner and able to meet the demand and supply gap of energy for development in an environmentally sustainable manner. Underground coal gasification is a neglected option.

Environmentally Sustainable Supplies of Energy with Specific Reference to Geothermal Energy

Although energy is the key element for improving the quality of life, ever increasing use of fossil fuels cannot be the basis for sustainable development. These have unexpected environmental consequences in local and global scale. The need to increase energy supply in a developing country like India is unquestionable. To meet the proposed energy needs, India must produce nearly double the quantity of coal (550 Mt/y) by 2010 AD, as it is mining at present. Rapid growth of the energy sector has made environmental protection a highly complex and more difficult task. There is a pressing need for alternate sustainable supplies of energy. This article examines the energy resources and some of the key environmental issues in these sectors. The focus is on the options available for the supply of energy. Geothermal energy, its potential, recovery, present scenario of utilization and its utility as a cleaner source have been discussed. The development of non-conventional energy in Indian context has been described. This article concludes by identifying geothermal energy as one of the potential sources of energy for maintaining a clean environment.