Pollution Prevention and Abatement Handbook WORLD BANK GROUP Effective July 1998

1. As of April 30 2007, this document is NO LONGER IN USE by the
Pollution Prevention and Abatement Handbook
World Bank Group. The new versions of the World Bank Group WORLD BANK GROUP
Environmental, Health, and Safety Guidelines are available at Effective July 1998
http://www.ifc.org/ifcext/enviro.nsf/Content/EnvironmentalGuidelines
Coal Mining and Production
Industry Description and Practices waste streams: fine materials that are discharged
as a slurry to a tailings impoundment, and coarse
Coal is one of the world’s most plentiful energy material (typically greater than 0.5 millimeters)
resources, and its use is likely to quadruple by that is hauled away as a solid waste.
2020. Coal occurs in a wide range of forms and
qualities; but there are two broad categories: (a) Waste Characteristics
hard coal, which includes coking coal, used to
produce steel, and other bituminous and anthra- The main impacts of surface mining are, in gen-
cite coals used for steam and power generation, eral, massive disturbances of large areas of land
and (b) brown coal (subbituminous and lignite), and possible disruption of surface and ground-
which is used mostly as onsite fuel. Coal has a water patterns. In some surface mines, the gen-
wide range of moisture content (2–40%), sulfur eration of acid mine drainage (AMD) is a major
content (0.2–8%), and ash content (5–40%). These problem. Other significant impacts include fugi-
can affect the value of the coal as a fuel and cause tive dust and disposal of overburden and waste
environmental problems in its use. rock.
The depth, thickness, and configuration of the In underground mines, the surface disturbance
coal seams determine the mode of extraction. is less obvious, but the extent of subsidence can
Shallow, flat coal deposits are mined by surface be very large. Methane generation and release can
processes, which are generally less costly per ton also be a problem under certain geological con-
of coal mined than underground mines of simi- ditions. If groundwater systems are disturbed,
lar capacity. Strip mining is one of the most eco- the possibility of serious pollution from highly
nomical surface processes. Here removal of saline or highly acidic water exists. Impacts may
overburden and coal extraction proceed in par- continue long after mining ceases.
allel strips along the face of the coal deposit, with Table 1 presents the levels of liquid effluents,
the spoil being deposited behind the operation solid waste, and dust generated by the major
in the previously mined areas. In open pit min- mining techniques.
ing, thick seams (tens of meters) are mined by Beneficiation plants produce large volumes of
traditional quarrying techniques. Underground tailings and solid wastes. Storage and handling
mining is used for deep seams. Underground of coal generates dust at rates of as much as 3
mining methods vary according to the site con- kilograms per metric ton (kg/t) of coal mined,
ditions, but all involve the removal of seams fol- with the ambient dust concentration ranging
lowed by more or less controlled subsidence of from 10 to 300 micrograms per cubic meter (µg/
the overlying strata. m3) above the background level at the mine site.
Raw coal may be sold as mined or may be pro-
cessed in a beneficiation/washing plant to re- Pollution Prevention and Control
move noncombustible materials (up to 45%
reduction in ash content) and inorganic sulfur (up Early planning and careful design of operations
to 25% reduction). Coal beneficiation is based on are the key to minimizing pollution associated
wet physical processes such as gravity separa- with mining activities. Specific responsibilities
tion and flotation. Beneficiation produces two should be assigned for the implementation and
282

2. Coal Mining and Production 283
Table 1. Loads Per Unit of Coal Production, by Mining Technique
(tons per 1,000 tons coal produced)
Surface mining Underground mining
Waste characteristic Contour Area Conventional Longwall
Liquid effluents 0.24 1.2 1 1.6
Solid waste 10 10 3 5
Dust 0.1 0.06 0.006 0.01
Note: Local conditions will form the basis for choosing the appropriate mining method.
Source: Based on Edgar 1983.
monitoring of environmental measures. Before • Reduction of dust by early revegetation and
mining begins, a mining plan and a mine closure by good maintenance of roads and work ar-
and restoration plan must be prepared and ap- eas. Specific dust suppression measures, such
proved. These plans define the sequence and as minimizing drop distances, covering equip-
nature of extraction operations and detail the ment, and wetting storage piles, may be re-
methods to be used in closure and restoration. quired for coal handling and loading facilities.
The plans should be updated regularly (every 3 Release of dust from crushing and other coal
to 5 years) as mining progresses. processing and beneficiation operations
should be controlled.
Development Plan • Control of the release of chemicals (includ-
ing floatation chemicals) used in beneficiation
The development plan defines the sequence and processes.
nature of extraction operations and describes in • Minimization of the effects of subsidence by
detail the methods to be used in closure and res- careful extraction methods in relation to sur-
toration. At a minimum, the plan must address face uses.
the following: • Control of methane, a greenhouse gas, to less
than 1% by volume, to minimize the risk of
• Removal and proper storage of topsoil. explosion in closed mines; recovery of meth-
• Early restoration of worked-out areas and of ane where feasible. (When methane content is
spoil heaps to minimize the extent of open above 25% by volume, it normally should be
areas. recovered.)
• Diversion and management of surface and • Development of restoration and revegeta-
groundwater to minimize water pollution tion methods appropriate to the specific site
problems. Simple treatment to reduce the dis- conditions.
charge of suspended solids may also be nec- • Proper storage and handling of fuel and chemi-
essary. (Treatment of saline groundwater may cals used on site, to avoid spills.
be difficult.)
• Identification and management of areas with Mine Closure and Restoration Plan
high potential for AMD generation.
• Minimization of AMD generation by reducing
The plan should include reclamation of open pits,
disturbed areas and isolating drainage streams
waste piles, beneficiation tailings, sedimentation
from contact with sulfur-bearing materials.
basins, and abandoned mine, mill, and camp
• Preparation of a water management plan for
sites. Mine reclamation plans should incorporate
operations and postclosure that includes
the following measures:
minimization of liquid wastes by methods
such as recycling water from the tailings wash • Return of the land to conditions capable of
plant. supporting prior land use, equivalent uses, or
• Minimization of spillage losses by proper de- other environmentally acceptable uses
sign and operation of coal transport and trans- • Use of overburden for backfill and of topsoil (or
fer facilities. other plant growth medium) for reclamation

3. 284 PROJECT GUIDELINES: INDUSTRY SECTOR GUIDELINES
• Contouring of slopes to minimize erosion and from these levels must be described in the World
runoff Bank Group project documentation. The emis-
• Planting of native vegetation to prevent sions levels given here can be consistently
erosion and encourage self-sustaining devel- achieved by well-designed, well-operated, and
opment of a productive ecosystem on the re- well-maintained pollution control systems.
claimed land The guidelines are expressed as concentrations
• Management of postclosure AMD and benefi- to facilitate monitoring. Dilution of air emissions
ciation tailings or effluents to achieve these guidelines is un-
• Budgeting and scheduling of pre- and post- acceptable.
abandonment reclamation activities. All of the maximum levels should be achieved
for at least 95% of the time that the plant or unit
Upon mine closure, all shaft openings and
is operating, to be calculated as a proportion of
mine adits should be sealed or secured.
annual operating hours.
There is a need to reserve money over the life
of the mine to cover the costs associated with
Air Emissions
mine closure. The amount of money and the type
of financing required will depend on a number
Controls may be required on individual sources,
of factors, such as the projected life of the mine,
such as ventilation exhausts, if they have a sig-
the nature of the operations, the complexity of
nificant effect on ambient particulate levels. If
environmental issues, the financial and environ-
coal crushers or dryers are used, fabric filters or
mental management capacity of the borrower or
other systems should be used to recover coal and
project sponsor, and the jurisdiction in which the
reduce particulate emissions to levels below 50
mine is located. The mine reclamation and clo-
milligrams per normal cubic meter (mg/Nm3).
sure plan, the timing of its submission, and its
financing should be discussed and agreed on
Liquid Effluents
with the borrower or sponsor as early as possible.
Settling ponds to catch stormwater and to reduce
Target Pollution Loads
suspended solids should be provided for all ef-
fluent before discharge from the site.
Implementation of cleaner production processes
Where treatment of AMD or other effluents is
and pollution prevention measures can provide
required, the effluent levels presented in Table 2
both economic and environmental benefits. The
should be achieved during operation and after
loads presented in Table 1 can be used as a guide
mine closure.
for pollution prevention purposes. The figures
relate to each of the production processes before
Ambient Noise
the addition of pollution control measures.
Noise abatement measures should achieve either
Emissions Guidelines
the levels given below or a maximum increase in
Emissions levels for the design and operation of
each project must be established through the en- Table 2. Acid Mine Drainage and Liquid
vironmental assessment (EA) process, on the ba- Effluents from Coal Mining
(milligrams per liter, except for pH)
sis of country legislation and the Pollution Prevention
and Abatement Handbook as applied to local con- Parameter Maximum value
ditions. The emissions levels selected must be
justified in the EA and acceptable to the World pH 6–9
Bank Group. TSSa 50
Oil and grease 10
The guidelines given below present emissions Iron 3.5
levels normally acceptable to the World Bank Total metals 10
Group in making decisions regarding provision
of World Bank Group assistance. Any deviations a. Monthly average, 35 milligrams per liter.

4. Coal Mining and Production 285
background levels of 3 decibels (measured on the lead to compliance with emissions guidelines can
A scale) [dB(A)]. Measurements are to be taken be summarized as follows.
at noise receptors located outside the project
property boundary. Develop and implement a comprehensive environ-
mental and mine management plan to include:
Maximum allowable log
equivalent (hourly • Restoration and rehabilitation of disturbed
measurements), in dB(A) areas
Day Night • Minimization of land subsidence
Receptor (07:00–22:00) (22:00–07:00) • Identification and management of AMD
sources
Residential,
institutional, • Water management for operations and
educational 55 45 postclosure conditions.
Industrial, • Management and sealing of pyrite-containing
commercial 70 70 piles to reduce AMD formation.
Monitoring and Reporting Develop and implement a post-closure plan to
include:
Frequent sampling may be required during start-
up and upset conditions. All wastewater dis- • Restoration of disturbed areas
charges from the operations should be monitored • Long-term geotechnical and geochemical sta-
weekly for pH, total suspended solids, and oil bility of waste piles
and grease. A full analysis covering iron and other • Restoration of acceptable long-term surface
trace metals should be carried out quarterly. water and groundwater flow patterns.
Where salinity is a potential problem, appropri-
ate parameters (chloride, total dissolved solids, References and Sources
and conductivity) should be monitored.
Ambient air levels of particulate material, in- Edgar, T. F. 1983. Coal Processing and Pollution Control.
cluding PM10, in and around mining operations Houston, Tex.: Gulf Publishing.
should be measured quarterly. Methane levels Hartman, Howard L., ed. 1992. SME Engineering Hand-
should be monitored, where appropriate, at least book, vol. 2. 2d ed. Littleton, Colo.: Society for Min-
annually even after mine closure. ing, Metallurgy, and Exploration.
World Bank. 1996. “Pollution Prevention and Abate-
Key Issues ment: Coal Mining.” Draft Technical Background
Document. Environment Department, Washington,
The key production and control practices that will D.C.