Now we get to know how mining companies can decrease the
probability of environmental impact during the second major phase of a mining
project that is the mineral production cycle which includes crushing,
concentration and final refining.
Cleaner technology can be used to control chemical hazards,
water contamination and air pollution during the processing phase of mining.
Environmentally sound processing techniques depend on the metal being mined.
Some metals require specific types of refining techniques and therefore have
distinct environmental impacts and mitigation techniques.
During the crushing and grinding phase of metal ore
processing, spraying the ore with water or dust suppressants can significantly
reduce dust production. Only recycled water should be used for this purpose,
and after use, runoff should be collected, treated and recycled. This can be an
effective use of recycled water from other processes that would otherwise be
treated and discharged. This can be an effective use of recycled water from
other processes that would otherwise be treated and discharged. Using water for
this purpose can reduce treatment costs as well. Dust can also be removed with
end-of-pipe solutions such as filters, wet scrubbers and other more advanced
technology.
One of the most common processes of the concentration phase
is the flotation which uses chemical reagents that can threaten the
environment. Froth flotation is a process for selectively separating
hydrophobic (lacking affinity for water) materials from hydrophilic (having a
strong affinity for water). For flotation methods, companies should install
computer-managed control equipment that improves the efficiency of metal
separation and metal recovery to effectively reduce the amount of reagent
required. A collection system should be installed to control and respond to
liquid spills and to direct effluent to a tailings disposal area.
Typically, process plant floors are sloped to collection
areas that pump spills back to the processing circuit. Secondary containment in
the form of specially lined holding tanks and piping made of impermeable
material will further reduce the potential for spills. Ammonia, a toxic
substance used during ore processing can be substituted with lime to reduce
acidity.
When metals are processed through heap leaching, heap piles
should be placed away from natural drainage areas and over impermeable clay
soil. Heap leaching is an industrial mining process to extract precious metals,
copper, uranium and other compounds from ore via a series of chemical reactions
that absorb specific minerals and then re-separates them after their division
from other earth materials.
Heap leaching should be designed to drain to specific
collection areas that can hold all flow and runoff, even from severe storms.
Two impermeable synthetic liners are recommended as well as underground leak
detection systems should be installed for heaps, ponds and drainage areas. The
mine should provide backup containment areas for pipes carrying leach solutions
and should monitor seepage and runoff from heaps. The cyanide solution should
be recycled until it is no longer potent; at this point it should be treated
before discharge, to render it non-hazardous.
As for the next topic, I’ll help you get to know how mining
companies deal with wastewater treatment.
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