Surface mining

People dig for things in the ground.

They move dirt and rock away first. This lets them reach the minerals. They use very big machines to do this.

Some mines are big holes in the ground.

This can change the land and the water. It can also make noise and dust.

Moving these things is a big job.

Surface mining is a way to get minerals from the earth.

In this way, workers remove the soil and rock on top. This top layer is called the overburden. This is different from underground mining. In underground mining, the rock stays in place.

There are many ways to do surface mining. Strip mining removes long strips of soil. This is often used for coal. Some machines used here are very big. One machine can move 12,000 cubic meters of earth every hour.

Open-pit mining uses a large hole in the ground. This works well for minerals that go deep down.

Another way is mountaintop removal. Workers use explosives to break up the rock. They then move the rock into nearby valleys. This can change the shape of the land.

Surface mining has some risks. It can cause noise and air pollution. It can also hurt the health of people. Dust from the mines can travel through the air. This can be a problem for nearby homes.

Surface mining is a way to get minerals from the earth.

This method involves removing the soil and rock that sits on top of a mineral deposit. Scientists and workers call this top layer the overburden. This is very different from underground mining. In underground mining, the rock stays in place while people use tunnels to reach minerals. Surface mining is used all over the world. In North America, it became very popular during the 20th century. Today, it produces most of the coal found in the United States.

There are several ways this work happens. In strip mining, workers remove a long strip of the overburden. This is often used for coal or lignite, which is a type of brown coal. Some machines used for this are huge. For example, a bucket-wheel excavator can move 12,000 cubic meters of earth in just one hour.

Another way is open-pit mining. This method creates a large hole in the ground to reach minerals that go deep down. There is also mountaintop removal. In this way, explosives break up the rock on top of a coal seam.

People have used surface mining for a long time. In North America, this way of mining began in the mid-16th century. Different types of mining have changed as technology grew. For example, highwall mining is a newer method. It evolved from a way called auger mining. It is a mix of surface and underground mining. It uses a machine called a continuous miner to reach coal. This machine uses a hydraulic pushbeam to move forward into the coal seam.

Mining changes the land in many ways. Mountaintop removal can make steep mountains look very flat. This can change the homes of many living things. In the United States, the EPA found that some streams near valley fills had different mineral levels.

Some people use the flat land left behind for new things. In Kentucky and West Virginia, people have built golf courses on reclaimed land. They have also built airports and even prisons. In the United States, a law from 1977 requires companies to fix the land after they finish mining.

Surface mining also affects the air and water. Dust from blasting can fly into the air. This dust might contain sulfur, which can hurt buildings or nearby homes. Mining can also cause noise and water pollution.

To move the heavy materials, people use different tools. Long ago, they used horses or manual labor. Later, they used mining railways.

Today, most mines use large haul trucks on special roads to move everything away.

Surface mining is a broad category of mining used to extract minerals from the earth. Unlike underground mining, which uses shafts or tunnels to reach deposits, surface mining removes the soil and rock sitting on top. This overlying material is known as the overburden. This method is used globally to find many different types of minerals. In North America, surface mining began to be used in the mid-16th century. It became very popular throughout the 20th century. Today, surface mines produce most of the coal mined in the United States.

The process of surface mining usually follows a specific sequence of steps. First, heavy equipment like earthmovers are used to remove the overburden. Once the mineral deposit is exposed, large machines take over. These machines might include dragline excavators or bucket-wheel excavators to extract the mineral. After the minerals are collected, they must be transported away. Historically, workers used manual labor, horse-drawn vehicles, or mining railways. Modern mines typically use large haul trucks on roads built specifically for the mine.

There are five main types of surface mining, each suited to different landscapes. Strip mining is a common method used for coal and lignite, which is brown coal. It involves removing a long strip of overburden to reach a mineral seam. This is most practical when the ore is near the surface and mostly horizontal. There are two forms: area stripping on flat terrain and contour mining in hilly areas. Some machines used here, like bucket-wheel excavators, can move 12,000 cubic meters of earth per hour.

Another method is open-pit mining, which creates a large pit or borrow on the ground surface. This technique is best suited for accessing mineral deposits that are mostly vertical. A different, more intense method is mountaintop removal mining, or MTR. In MTR, explosives are used to break up the overburden above a coal seam. This material is then moved by haul trucks into fills in nearby valleys. This process can change a steep mountain into a much flatter landscape.

Highwall mining is a more specialized method that is considered a semi-surface and semi-underground technique. It evolved from auger mining to recover coal adjacent to an area that was already surface-mined. It uses a continuous miner propelled by a hydraulic pushbeam transfer mechanism, or PTM. The machine goes through cycles of sumping to push forward and shearing to cut the coal. Operators use tools like gamma-ray sensors or coal-rock interface detection sensors to see the seam. This method displaces very little soil compared to mountaintop removal.

Finally, dredging is a method used for mining below the water table, often for gold. Small dredges might use suction to pull material from the bottom of a water body. Large-scale historical operations used floating dredges, which are barge-like vessels. These vessels scoop material via a conveyor belt on the bow. They filter the desired mineral on board and return the unwanted material via a conveyor on the stern.

While surface mining is often cheaper and safer for workers than underground mining, it has many environmental impacts. It can cause habitat destruction, noise, and air pollution. Blasting at mountaintop mines can release dust containing sulfur compounds. This dust can settle on nearby property and may be a health hazard. The U.S. Environmental Protection Agency (EPA) found that valley fills can increase mineral levels in nearby streams. This can lead to decreased aquatic biodiversity.

Despite these challenges, some land is reclaimed after mining is finished. In the United States, the Surface Mining Control and Reclamation Act of 1977 mandates this process. In areas like Kentucky and West Virginia, reclaimed land has been used for many things. Some sites have become golf courses, small-town airports, or even prisons. Proponents say this provides much-needed flat land for use in hilly regions. However, critics argue that the changes to the ecosystem and topography are too profound.