Mineral Production Cycle - Part 1

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.