What Is Surface Mining?

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Ever wonder to yourself: what is surface mining?

If so, this is the article for you. We’re going to explain what surface mining is and give you some information about the MSHA Part 46 training requirements for surface mines to boot.

If you read through this and are still wondering about the surface mining definition, leave a note in the comments below.

And let us know if you’d like some additional information about online safety training for surface mining too (MSHA Part 46 training).

What Is Surface Mining? The Definition

So what’s the definition of surface mining? As stated by GreatMining.com, it’s:

Surface mining is a form of mining in which the soil and the rock covering the mineral deposits are removed. It is the other way of underground mining, in which the overlying rock is left behind, and the required mineral deposits are removed through shafts or tunnels.

Our friends at AZO Mining provide some additional context:

There are two basic classes of mining: mining at the Earth’s surface and mining underground…Surface mining accounts for two thirds of the world’s solid minerals, and is predominantly used in obtaining sand, gravel, crushed stone, phosphates, coal, copper, iron and aluminum…

There are 5 main types of surface mining, which are used in various degrees and for different resources. These mining categories are: strip mining, open-pit mining, mountaintop removal, dredging and high wall mining. All methods of surface mining will remove the waste material, or overburden, above the desired resource.

Surface 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.

Let’s look more closely at those different types:

Open-pit Mining

Open-pit mining is the most common type of surface mining.

An open-pit mine is exactly what the name implies: a big hole (or pit) in the ground.

The pit in an open-pit mine is created by blasting with explosives and drilling. This type of mining is typically used to mine gravel and sand and even rock (when open-pit mining is used to extract rock from the earth, the pit is often called a “quarry”).

High Wall Mining

High wall mining is a combination of surface mining techniques and sub-surface techniques.

The basic idea is you start with an open-pit mine, and then drill or bore into those walls to extract more resources.

High Wall mining is performed remotely by a person in a cabin at the surface who uses a television camera to monitor and control the continuous miner machine.

Dredging

Dredging is the process of mining materials from the bottom of a body of water, including rivers, lakes, and oceans.

Strip Mining

Strip mining is the process of removing a thin strip of overburden (earth or soil) above a desired deposit, dumping the removed overburden behind the deposit, extracting the desired deposit, creating a second, parallel strip in the same manner, and depositing the waste materials from that second (new) strip onto the first strip. And so on.

Strip mining is  using a lot for coal, phosphates, clays, and tar mining.

Mountaintop Removal

This is an alternative, and more recent, version of strip mining.

As the main suggests, mountaintop removal mining involves removing the top of steep mountains to expose desired deposits below. The excavated overburden from the mountaintop is deposited in nearby low valley areas known as “valley fills.”

This method is for the most part confined to coal mining in the Appalachian region of the United States.

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Common Physical Characteristics of Surface Mines

In this section, we’ve got a super-cool interactive glossary that defines and illustrates many of the physical characteristics you’ll see at a surface mine.

Then, after that, we just straight-up define those for you in text. In case you don’t like super-cool, interactive multimedia or whatever.

But let’s start with that glossary, which, by the way, is from our General Physical Characteristics of Surface Mines online safety training course.

Here it is. Hope you enjoy it.

If you liked this glossary a LOT, you can download it for free here (please read the further explanations of exactly what you’ll download, how you’ll receive it, and how you can import it into your LMS on the next page).

And now, here are the definitions of many of the different features you’d find at a surface mine, printed out all old-skool in black and white for you.

Pit

The dominant feature in an open pit or quarry operation is the “pit,” a broad, deepened, often funnel-shaped area where material extraction and other active mining activities take place. The pit is created when the overburden, the rock or soil overlaying a deposit of minerals or stone, has been removed to access the material being mined.

Benches

Benches are terrace-like steps cut into steep hillsides or into the sides of an open pit. Benches help prevent rock slides into active mining areas by providing flat areas at intervals that slow or stop any falling material. Ranging from 25 to 60 feet in height, benches are usually cut and graded wide enough for two haul trucks to pass one another safely.

Highwalls

At surface mines, highwalls are unexcavated faces of exposed overburden which can range in height from 20 feet to more than 100 feet, depending upon the geological characteristics of the area and the material being mined.

Angle of Repose

The slope at which a material naturally comes to rest is referred to as the “angle of repose.” Each material’s angle of repose varies based on the nature of the material. 

Understanding the angle of repose is critical to assessing the safety of highwalls or piles of unconsolidated material. When a material rests at an angle greater than its angle of repose, it can become dangerously unstable. Typically, the steeper the angle, the more likely a slide or collapse will occur.

Stockpiles and Wastepiles

Stockpiles and wastepiles are volumes of mined material which have been built up by conveyors or haul truck dumping. They can range greatly in size and height, depending upon the mining operation, the nature of the mined material, and the purpose of the pile.

Haul Roads

In addition to providing truck haulage paths, haul roads define the general operational flow of equipment and material throughout active mining areas.

Haul roads are specifically designed to provide safe operation and travel of mining equipment. Haul roads are recommended to be twice the width of the largest equipment using the road at the mine and the road must be designed and graded so that an operator is able to stop a vehicle within the available site distance.

Berms

Berms are long, low piles of material built up to at least the mid-axle height of the largest mobile equipment which usually travels the roadway at the mine. They are placed and maintained in specific locations in order to clearly define safe limits of vehicle passage and dumping. Properly located and built berms help define the edges of haul roads and piles, mark the safe stopping distance at which loaders may dump material onto a pile, and may provide a sensation of contact to give the vehicle operator the opportunity to regain control and keep the vehicle from leaving the roadway.

Settling Tanks or Ponds

In operations where aggregate and other potential construction material is mined, washing may be part of the process. The used wash water may be piped to settling tanks or ponds where it can be reused after unwanted sediments have settled to the bottom. The size and location of these features will depend on the mining operation and material being mined.

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Common Equipment Used in Surface Mining

OK, now that we’ve discussed the physical characteristics at a surface mine, let’s talk about some of the equipment you might see there.

As before, we’re doing this in two parts. First, a cool, interactive glossary. Then, the straight-up definitions.

Here is the glossary. Hope you enjoy it. This is from our Typical Surface Mining Equipment online training course.

If you liked this glossary a LOT, you can download it for free here (please read the further explanations of exactly what you’ll download, how you’ll receive it, and how you can import it into your LMS on the next page).

Dredges

Dredges are a type of excavation equipment used to remove material from underwater. They can be land-based or barge-mounted and may employ powerful suction or physical digging methods to bring material to the surface for removal or processing.

Dozers

Bulldozers, often referred to as “dozers,” are track-mounted vehicles equipped with a wide, vertical front-mounted pusher blade that can be raised and lowered during operation.

Heavy, powerful, and extremely stable, dozers are typically used to clear land, push material short distances, do grade work, and manage stockpiles and work areas.

Backhoes

Either track-mounted or tire-mounted, backhoes are a type of excavator equipped with a bucket that faces toward itself. The typical backhoe design incorporates an inward-facing bucket affixed to an articulated arm, or “boom.” Backhoes are often used for removing and loading overburden as well as scraping down high banks and digging ditches.

Shovels

Shovels, sometimes called “power shovels,” are versatile excavation machines, often track-mounted, with a large, outward-facing bucket at the end of a powerful, articulated boom that can rotate 360 degrees. Shovels are used primarily to dig out and remove overburden as well as selectively load material for transport.

Draglines

Draglines, a type of specialized excavation equipment, operate by casting a heavy cable-hung bucket outward from a crane-like boom and dragging the bucket toward itself to remove large amounts of overburden, load ore, and manage stockpiles. Draglines can be equipped with buckets of specific design and weight to match the materials being mined.

Front-End Loaders

Front-end loaders, or simply “loaders,” are large, typically tire-mounted vehicles with a deep, wide bucket mounted at the front. Loaders are used to load mined material into haul trucks and feeders, push or dump overburden, and manage stockpile or refuse areas. In sand and gravel operations, loaders may also be used for excavation.

Haul Trucks

Haul trucks, or “haulers,” are tire-mounted vehicles with a deep, wide hydraulically operated dump bed commonly used to transport and place large volumes of mined material from the pit to stockpiles.

Track Haulage

Track haulage involves the loading and management of specially designed railroad cars to transport enormous volumes of overburden or mined material to other areas of the mine or off-site to distant locations.

Water Trucks

Water trucks are tanker trucks used to help suppress dust and other airborne particulate hazards by spraying water on haul roads, access roads, and common work areas.

Human Transport

Active mining operations are often spread across a large area, making walking to distant locations impractical and potentially dangerous. Miners, contractors, and supervisors often need to move quickly between work areas to do their jobs, perform maintenance, and address issues as they arise. A broad range of common passenger vehicles and pickup trucks may share haulage roads to transport people, tools, and small equipment where they are needed.

Scrapers

Scrapers are a type of earthmoving machine with an open, centrally mounted hopper or bowl with a blade-like leading edge that can be raised or lowered hydraulically to selectively remove and spread overburden over level or relatively level terrain.

Skid Steers

Often tire-mounted, skid steers are quick, compact, highly maneuverable, and extremely versatile machines which perform a broad range of vital duties throughout the mine. They may be used in excavation work to carry, spread, and load loose material as well as serve an array of grading, site preparation, construction, demolition, and repair functions.

Cranes

Cranes are a type of lifting equipment typically used to lift, place, and transport heavy items such as equipment, building materials, and mined material over short distances.

Although some cranes can be stationary, many are mobile units that may be tire-mounted, track-mounted, or truck- mounted. 

Stationary Equipment and Structures

Stationary equipment at a surface mine typically performs hauling, processing, and other service functions. Structures provide offices, storage, and maintenance spaces. 

The following stationary equipment and structures are common to most surface mining operations:

Conveyor systems

Feeders, bins, and hoppers

Crushers and screens

Classifiers

Water reclamation systems

Buildings and other structures

In-Pit Conveyor Systems

Belt conveyors are designed to carry bulk material on a wide belt that rotates around two or more pulleys. At least one of the pulleys are driven by a motor that powers the conveyor system.

In-pit belt conveyors are used to move material within a large, active mining pit area or from the pit to loading areas for further distribution within the mine. In-pit conveyors may also move mined material to portable crushing systems that reduce the size of larger rocks or minerals for easier transport.

Overland Conveyor Systems

Overland belt conveyors are used on mine sites where there is the need for continuous movement of high volumes of material over long distances, in some cases, several miles. This type of bulk material handling conveyor may be used to transport material from the pit to processing areas or loading areas for rail or barge transport.

Screw Conveyors

Screw conveyors use a rotating, helical screw to move liquid or granular materials through a tube or trough. The screw is commonly referred to as a “flighting” and may either wrap in a spiral pattern around a central shaft or be “shaftless.”

Bins, Hoppers, and Feeders

Bins, hoppers, and feeders are types of equipment used to help regulate the flow of material through the mining process.

Bins and hoppers are containers with open tops for material to enter and an opening at the bottom for material to exit, typically over a conveyor or feeder. They are filled from the top by a loader or conveyor and discharge material at a continuous rate through the opening at the bottom for distribution to other processing and sorting operations.

Feeders transport material a short distance at a consistent rate using conveyor belts or screw conveyors. Feeders may also have an integrated breaker mechanism used to reduce material size as needed for the next processing stage.

Jaw Crushers

Jaw crushers are often used early in the production process to prepare material for processing. Raw mined material enters the top of the machine where a moveable “jaw” opens and closes repeatedly to break the material against a fixed stationary plate. When the material has been reduced to a size small enough to pass through the opening below the jaws, it exits the crusher and may be further sorted for stockpiling or downstream processing.

Cone Crushers

Cone crushers are typically used in downstream crushing operations for medium-sized materials. Like the jaw crusher, the material is fed into the cone crusher from the top and discharged at the bottom. As the material enters the crusher, an eccentrically rotating cone forces the materials against a crushing plate. The shape and movement of the cone progressively reduces the size of material as it moves down through the crushing chamber to the sizing gap above the discharge opening. Resized material may be further sorted and transported to stockpiles or other processing operations.

Screens

Screens are a type of equipment used to separate particles into various sizes or “grades.” In some cases, screens may also be used to differentiate between the wanted and unwanted materials.

Classifiers

Classifiers are a type of sorting system used to separate coarse and fine particles from one another using water. They are typically located downstream of crushers and screens.

Some of the most common types of classifiers are spiral and rake classifiers. Both of these classifiers separate material by dragging the material along the bottom of an inclined surface in a settling chamber from the bottom (inlet) to the top (discharge).

Water Reclamation System

Water reclamation systems remove fine sediments and return a high percentage of the used water back into the mining process. These systems may involve large settling tanks, mud presses, storm water discharge areas, and extensive piping and pumps to reduce runoff, manage environmental impact, and conserve resources.

Buildings and Other Structures

Other physical elements of a mine include structures relevant to operational oversight and equipment maintenance. Management offices, workshops, storage, refueling, and power generation may all be located on-site. In some cases, a control tower may also be constructed to offer a complete view of processing operations.

Maintenance and Repair Shop

A range of mobile and stationary equipment may be in constant use at a mine, requiring dedicated space for maintenance, repair, parking, and vehicle storage.

Most mines will have a maintenance and repair shop onsite to store replacement parts, supplies, tools, and other specialized machinery while providing sufficient space to maintain and repair equipment. 

Fuel Tanks

Surface mines require the constant operation of heavy equipment consuming large volumes of liquid fuel. Since much of this equipment is not designed to be driven on conventional roadways, refueling must be done on-site making fuel tanks and pumps a necessity. Tanks may be above or below ground and can range in size from 500 to many thousands of gallons.

Generators

Both stationary and portable electrical generators commonly serve a wide range of power needs at a mine. 

Truck and Wheel Washes

Truck and wheel washes are specialized areas or automated systems designed to remove obstructive dirt and mud buildup as well as dust and potentially hazardous particulates from mining equipment. 

While a truck wash may serve to wash large vehicles, wheel washes are generally simple, drive-through baths along a drive path. 

Truck Scales

Since mining operations exist for the purpose of selling extracted and processed commodities, industrial truck scales are put in place to keep track of transported material volumes. Truck scales are normally situated on drive paths close to where over-the-road trucks exit the mine carrying processed material to customers.

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Conclusion: So That’s What Surface Mining Is!

So if you began this article by asking yourself “what is surface mining,” we hope you’ve got it now.

You may find these other articles helpful as well:

And don’t forget, we can help you out if you’re looking for options for MSHA Part 46 Online Safety Training Videos.  Our MSHA Safety Training won the ISHN Best Safety Training Award–did you know that? We’re proud of it and you’ll see why.

And don’t forget to download the free guide below, too.

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Jeffrey Dalto

Jeffrey Dalto

Jeffrey Dalto is an Instructional Designer and the Senior Learning & Development Specialist at Convergence Training. Jeff has worked in education/training for more than twenty years and in safety training for more than ten. You can follow Jeff at LinkedIn as well.

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