Land clearing and stripping in Mining Operations
Land stripping and clearing prior to setting up new mining operations is an important part of the undertaking to remove valuable resources from the ground. Not only do mine operators strip existing vegetation, but they also need to ensure that their processes do not disrupt the environment too harshly for the long term.
What is land clearing and stripping?
Land stripping or land clearing involves removing all or any portion of existing vegetation from parcels of land with specialised equipment. Heavy duty machinery plows or scrapes the ground surface to remove trees, stumps and other vegetation from wooded areas.
Surface mining (also called strip mining and referenced in this article) impacts the environment acutely because of the sheer volume of land involved. This kind of undertaking can have the following impacts:
- Cause soil erosion or a reduction in the earth’s fertility;
- Pollute waters or drain underground water reserves;
- Blemish or radically alter the landscape;
- Damage roads and other nearby structures;
- Destroy wildlife;
- Create air pollution from the dust and particles of mining roads and stockpiles.
It is, therefore, extremely important that new operators have prior expert opinion on the best way to go about the process, in order to prevent landscape shock once the mining operation has run its course. Unitrans Africa can assist with this audit and assessment.
How is land clearing done?
All surface or strip mining first removes the covering vegetation, soil and top layers of rock in order to expose the minerals or coal deposits. Responsible mining attempts to limit the side effects of this removal when carrying out the usual basic steps:
- The first step is to clear the vegetation (trees, bushes, etc.), also called ‘scalping’ in some countries.
- The operator then removes the topsoil, usually with bulldozers and loaders, either to stockpile the topsoil for later use, or to spread it over an area that already has been mined.
- Next, he turns his attention to the exposed overburden1 which he drills and/or blasts for removal by bulldozers, shovels and excavators, depending on the type of mining and/or the amount of overburden.
- When undertaking coal mining, operators fracture the exposed coal seam with explosive blasting. They then load this onto trucks or conveyor belts to haul off the product. This process continues during the life of the mine.
- Once the resource is all mined/extracted, mine managers must grade, crush and compact the original overburden or waste material and then re-distribute it over the land area affected by the mine. Most countries legislate that mine operators must rehabilitate the location with topsoil and re-vegetation procedures.
Environmental impacts from strip mining
Strip mining accounts for about two-thirds of the world’s solid minerals, and is predominantly used to extract sand, gravel, phosphates, coal, copper, iron and aluminium.
Surface or strip mining is often preferred to sub-surface (underground mining) by mining companies for several reasons:
- It is less expensive,
- there are fewer complications in terms of electricity and water and
- it is safer.
While the basic steps of land clearing are relatively consistent among operators, the environmental impacts vary for small or large clearances. When land clearing is extensive, the effects can be irreversible, but when the clearing is minimal, the effects can be reversed.
The largest threat to the environment lies with irreversible clearance that can destroy an entire ecosystem causing negative effects, such as erosion, greenhouse gas emissions, a rise in soil salinity2, the destruction of natural territories for animals, and decrease or even render indigenous flora extinct.
While at one time land clearing was seen as beneficial and even progressive, we now view it as potentially destructive. But there is now more environmental awareness, so most countries which use land clearing have specific legislative regulations in place.
Equipment used in overburden removal for mining
Bulldozers are the most productive pieces of equipment used in large land-clearing operations, with a variety of specialised attachments available to make the job easier. Some of these are:
- A root plow to remove shrubs and bushes and
- A heavy-duty rake to remove small trees, rocks and stumps.
To remove vegetation, this heavy equipment completely disrupts the ecology of the land, introducing erosion on a large scale. Though bulldozers can remove unwanted trees, the weight of the machines also crushes or exposes the roots of surrounding trees, thus disrupting the ecology of the area.
After felling the trees, operators transport the logs to other locations with further heavy equipment or they pile and burn the overburden. Without due care and attention, bulldozing can leave an unsightly mess.
Excavators are other pieces of equipment also used for land-clearing activities, mostly on larger sites. As with the bulldozers, there are attachments or additional equipment to assist the operator in doing the job correctly:
- Grappling hooks reach, grab onto and remove small trees, brush and logs;
- Stump pullers or grinders for removing tree stumps; and
- Heavy-duty rakes or rock pickers for gathering rocks before they are loaded onto trucks.
Speak to Unitrans Africa about using the right equipment for the task on hand. They provide a variety of services for mining operations, including input to streamline production and save costs. The company is proud of its logistical innovation to create greater payloads, reduction in fleet requirements, decreases in environmental emissions and an increase in safety standards. Material-handling solutions include recommending a fleet of purpose and speciality-built machines to ensure mining operators can meet the size and detail requirements of their projects.
As a leader in mining solutions in Africa, with a strong footprint in countries such as Botswana, Madagascar and Namibia, Unitrans Africa is the right call to make. Find out more about land clearing solutions by getting in touch with one of their professional consultants.
1 In mining, overburden (also called waste or spoil) is the material that lies above an area that lends itself to economical exploitation, such as the rock, soil, and ecosystem that lies above a coal seam or ore body. Overburden is removed during surface mining, but is typically not contaminated with toxic components (Wikipedia)
2 A change in the salinity levels in soil can transform fertile land to unproductive land, which ultimately results in economic loss.