What Is Open Pit Mining? | An Underground Miner

Open-pit mining is a surface mining technique that involves extracting minerals from ore deposits near the topsoil.

Unlike conventional underground mining methods, these operations are extensive projects that form canyon-like features in the landscape.

Open-pit mining companies use modern tools and technology to excavate the earth's surface meticulously.

As a result, much of the surrounding environment sustains long-lasting geographic changes.

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Our dedicated team of industry professionals explains everything about open-pit operations.

Read on to learn the mining science behind this industry and its benefits and impacts.

Many economies worldwide rely on open-pit mining to source valuable materials for trade and manufacturing.

It is generally three to five times more productive than traditional underground mining.

As a result, major extraction companies enlist thousands of workers around the globe to maintain these sites.

Although open-pit mining is a dangerous profession, workers can appreciate safer and more hygienic work environments than traditional methods.

Companies also enjoy a complete extraction of materials at the expense of less capital.

A surface mine can produce dozens of mineral types in the same pit. That is why the modern industry invests so heavily in this strategy.

Due to high-performance results, this mining approach will likely stand firm for the foreseeable future.

Open-pit mining, known by many professionals as "open cast mining," shares features with other surface strategies. Still, differences help distinguish these techniques.

Strip mining is a surface technique where workers clear vegetation, waste rock, and overburden from the ground. Typically, miners use these operations for extracting rock and coal from just below the surface.

Open-pit mining differs as workers excavate large landscapes on deeper slopes, separated by "benches."

A bench is a feature of the mine where workers perform blasting, drilling, and hauling; they usually rely on more robust tools for cutting out these features.

Still, open-pit mining may utilize strategies similar to strip mining, especially when minerals are present on or near the surface. Workers will sometimes develop the site around these areas and carefully strip the minerals from the surface.

An extensive ground survey allows the company to analyze its space and decide which strategy is best for its goals.

While open pit mines can certainly reach low elevations, deep mining operations typically function at excessively lower depths.

Still, both mining strategies can potentially access deep groundwater levels, creating obstacles for miners.

Shaft mining can be considerably more dangerous for workers. Cave-ins, gas leaks, and other health hazards create anxiety on the job. Many workers prefer the safety of the surface to conduct their excavations.

In addition, an open-pit mine generally integrates large-scale hydrology solutions to prevent acid mine drainage.

High wall mining is a great way to avoid the costs and energy of conventional tunneling.

This process extracts ore and waste rock from the exposed high wall after workers reach the strip limit.

Image: Copyright © 2019 Rio Tinto

Pit mining may require small to large swaths of land for economic practicality. The target ore deposits will determine the size of the workspace needed.

For example, one pit may reach just below the surface, while another could be dozens of meters deep.

The deepest open pit mine is the Bingham Canyon Mine in Salt Lake City. This open cast pit reaches a depth of about 1.2km.

Modern mining technology allows workers to excavate large tracts of land with relative ease. However, some limitations prevent efficient open-cut mining.

Rock falls are typical features of surface mines that can endanger workers and equipment. In these instances, additional ground support must stay vigilant of potential hazards on site.

Miners must constantly monitor slope stability to ensure that benches withstand operational demands.

Mineral or ore deposits range depending on the mine and can help workers determine the stability of their mining site.

If the hole location is not stable, structural weaknesses occur in the angled and stepped sides of the pit. This problem delays work and can endanger the team.

Spaces like these can be a treasure trove of heavy metals and minerals.

Conventional mining sites generally specialize in a single mineral. An open-pit mine can extract a broader range of products in the same pit.

Some of the materials typically extracted from these mine sites include:

• Iron ore
• Copper ore
• Coal
• Marble
• Oil shale
• Uranium
• Gravel
• Stone
• Limestone
• Phosphate
• Clay
• Granite
• Diamonds
• Chromite

Over the decades, the mining industry has developed excellent solutions to efficiently identify and extract these materials.

Complete extraction of minerals like coal and iron was once a challenging task.

Modern surface mining makes it easy to locate and pull these minerals from the earth.

Workers can enjoy various open-pit mining methods, such as:

• Blasting rock to remove challenging impasses
• Drilling for precise excavation
• Hauling the ore body from the site for processing

Open cast mining requires modern tools for mineral exploration and digging. The process includes technology like:

• Heavy vehicles for drilling and hauling
• Controlled explosives
• Hydrology (such as plumbing materials and cabling) to relieve water pressure under the surface
• Hand equipment
• GPS and ground mapping technology

Surface mining methods continue to evolve as new information and technology streamline and scale operations across the globe.

This method is perhaps the most intensive in the open-pit mines. A mining technique like this requires careful oversight to maintain the safety and integrity of the open pit.

Miners utilize this method for stripping hills and other elevated surfaces where exposed minerals present themselves.

Though they require careful planning and care, it tends to be less dangerous and labor intensive than deeper pit mining techniques.

Waste rocks are minerals that do not serve the economic purpose of the operation. These are usually by-products of the excavation or material that impedes further mining.

Workers will haul these elements to waste dumps, where they either stay or undergo processing to extract overlooked metal ores.

Open-pit mines are high-demand sites requiring hundreds, if not thousands, of workers. Like any other blue-collar operation, the workforce must adhere to extensive safety rules and regulations.

Workers' safety typically includes hard hats that protect them from falling rocks or tools. Some open-pit mines require workers to use masks or filters. These tools protect them from dust or toxic elements, such as in the case of coal mining.

An open-pit sulfur mine can create significant risks to human health and the environment.

Workers undergo specific training to identify dangerous features they may operate in or around. With this wisdom, they better protect themselves on the job.

Open cast mining operations can last for several months or years. During this period, the mine area will significantly transform in shape and quality. Workers need to remove the solid and liquid waste that accumulates.

Mining uneconomic materials from the mineral deposit indicate that operations will begin to close out.

During mining activity, workers transfer many unusable products to a waste dump. Once mine closure looks imminent, a more thorough cleanup strategy begins.

Workers must take several steps to secure the site before their exit.

To prevent rock falls from continuing, miners implement measures that secure the area from this and other hazards.

Removing dangerous waste material is one step of the process. They must also ensure that tools, chemicals, and explosives are secure.

Many of these items can negatively impact the environment when left behind.

Sometimes, the company will fill areas of the site with soil to protect against dangerous slopes or unstable structures. Larger sites require a more thorough approach.

It is typical for a company to convert exhausted mines into landfills. Most policies attempt to prevent a settling pond or lake from forming in these spaces.

Open-pit mining can unearth several toxic chemicals and heavy metals that may drain into nearby rivers.

To avoid this, miners can implement precautions that route water out of the open pit and surrounding environment.

These procedures may begin as early as the initial excavation. Workers check for any surface water in the pit forming during operations.

Water presence may also indicate that activity has penetrated the water table.

Mining finishes when the site is secure. Workers will appropriately dispose of harmful materials in designated waste dumps by this point.

Surface mining can create long-term impacts on the environment, depending on the intensity of the operation.

The modern mining industry does what it can to circumvent damaging disasters. Still, some geographic limitations can make mitigation difficult.

Toxic runoff from surface mining can contaminate lakes, rivers, or the water table. Acid drainage is a serious health risk that may reduce drinking water quality for some communities. It can also endanger local wildlife and habitats.

Surface mining uplifts large quantities of dirt and dust that lingers over the environment. For some uranium open-pit mines, that means the release of radioactive elements into the air.

Blasting is a common surface mining technique that can lead to fires. While miners typically contain these disasters on-site, natural gas buildup fuels these fires. Excessive smoke and gas can negatively impact local air quality.

Converting a surface pit into a waste dump comes with risks. Many communities fear the unsustainability of landfills around their environments.

Some companies choose alternative landscape rehabilitation options to ease these concerns, such as:

• Filling shallow pits with soil
• Fencing the area from wildlife and trespassers
• Clearly marking sites for future landscapers

The most pressing concern for the mining industry is developing technology and strategies sustainably. These solutions should keep both the environment and the workers safe.

The advent of new technology continues to scale back certain operations that were once labor exhaustive and dangerous.

Using tools like ground penetrating radar systems helps miners identify concentrations of ore. This information allows them to scale back their excavation and create less environmental harm.

Sustainable technology reduces the output of pollutants and chemicals that may cause harm to life.

Landscape development and rehabilitation also allow companies to restore areas that experienced heavy mining activity.

Zoning and legislation continue to regulate the spaces in which companies can operate.

Protected habitats and at-risk communities find relief knowing open-pit mining will not impact their homes.

These industries also rely on the future of global and domestic trade demands.

The value of certain metals fluctuates and may impact the need for mining in some areas.

Open-pit mining is an integral part of our economic culture. These companies extract and process raw materials with methods that streamline the creation of many of our daily comforts.

However, innovation continues to make the mining process more manageable.

Companies enlist thousands of workers around the globe to provide safe and effective extraction on these sites.

Although these methods come with risks, most miners prefer this environment over the dangers of tunneling.

Laws and regulations continue to protect workers and the environment from dangerous practices.

Open-pit mining is a testament to the ingenuity of miners and their parent companies.

As they continue to evolve and adapt, they also uncover greater rewards.

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This article was written by An Underground Miner