Understanding Mining Waste Management and Disposal Methods

Understanding Mining Waste Management and Disposal Methods 

Written by Erich Lawson for Compactor Management Company

Mining produces a lot of waste which needs to be handled properly.  Improper mining waste disposal will lead to air, soil, and water pollution.  Different types of mining include landfill mining, coal mining, oil and gas extraction, metal, and non-metal ore mining. 

In this article, we will look at different types of mining waste and how to manage it effectively.  

Types of Mine Waste 

1. Rock or Solid Mine Waste

• Waste rock or overburden

This refers to the large mass of initial soil and rock that is removed to get the mineral deposits.  Generally, around five tons of overburden must be displaced to mine a single ton of ore.

Overburden mining is not subjected to any chemical processes; however, overburden still needs to be removed to reach the mineral ores.  You can manage overburden by piling it on the nearby surface of the mining site where it won’t interfere with the ongoing operations.

• Gangue

This is the rock waste that is mixed with the valuable mineral and needs to be processed.  The separation of the mineral from the gangue is known as mineral processing.

The gangue needs to be reprocessed a few times to extract all the minerals from it as some amounts of minerals may be missed during the first processing. 

• Mine Tailings

These are finely ground rocks and mineral waste that is a result of mineral processing.  They can contain concentrations of processing chemicals.  They are an environmental concern, which is why proper transportation and disposal are crucial. 

The mine tailings are pumped with slurry pumps into tailing ponds.  These are sedimentation holding ponds that are enclosed by dams to capture and store waste.

2. Liquid Mine Waste

• Mine Water

This is produced in different ways at mine sites and has different levels of contamination.  Water that is exposed to various mining processes is usually acidic and can contaminate the local water sources.  This process is called acid mine drainage and it contributes to water pollution.

Carefully monitor water at mine sites and devise mine water management strategies to reduce the amount generated.  This water must be treated before it is released into the environment. 

• Sludge

Similar to mine wastewater, sludge is produced at some mine sites.  The difference between the two is that sludge has the additions of solids and processing chemicals. Sludge has very little economic value which is why it is handled as waste.

If the sludge has harmful or radioactive material, it may be classified as hazardous waste. This will require special handling and disposal methods.

Mine Waste Management

The local government bodies and the public keep a close eye on the waste disposal methods of mining companies.  In the past, improper disposal of mining waste resulted in environmental damages.  This is why mining companies needed to come up with better ways to dispose of mining waste without hurting the environment. 

• Disposal

Grinding and adding water and chemicals is a typical step of processing ores in the ore treatment refining plant.  A large portion of the waste leaves the plant in the form of slurry.  The free water in it is then pumped back into the plant.

The gangue and other rock waste are disposed of by storing them in waste piles or in the base of tailings dam embankments.  The major portion of the waste rock is disposed of in piles at the source. 

The coarse coal refuse is removed from the preparation plant and disposed of in large piles or banks.

The tailings are disposed of through pond storage, dry sacking, into underground workings, or in the ocean.  Based on the type of tailing, the right disposal method must be chosen.

• Overburden Management 

The way to manage overburden is by backfilling it back into the excavated mine land.  Overburden dumps are usually reclaimed by tree species as plantation improves the pH, moisture content, and overall nutrient content of the soil.

Ensure that a new pit is excavated only after an existing pit has been exhausted.  The overburden should be properly stacked and compacted.  Maintain the height and slope of the overburden dump to prevent accidents.  Finally, consider drainage to handle heavy rainfall.

• Recycle 

Some of the mining waste can be recycled.  The mining industry can make use of its own waste material by reprocessing to recover additional minerals or using them for internal construction purposes.

Mine waste material can be reused in the construction of impoundments and haul roads.  Certain tailing waste can be used as granular base/subbase, flowable fill aggregate or fill, engineered fill or embankment, or asphalt aggregate.

Final Words

Since mining is done in large quantities, it becomes imperative to manage the generated waste properly.  Understand the type of waste your mine produces and dispose of it accordingly.  Be aware of the latest methods and technologies to achieve the same.