A mining excavator is a type of heavy machinery used to dig raw material in mining operations, particularly surface mining. Several types of excavator are commonly used in surface mining operations, including backhoe excavators, power shovels, bucket wheel excavators, and dragline excavators. While some mining excavators may be essentially no different than the typical backhoe excavator seen at any construction site, other machines of this type are among the largest machines ever built and are capable of excavating hundreds of cubic meters of material per hour.
A backhoe mining excavator is configured like the backhoes used in construction and non-mining excavation projects, except that in mining operations, wheeled tractor type backhoes are not usually used. A self-contained cab is mounted on a body that houses the engine and other components of the machine. This part of the machine is mounted by means of a large swivel joint atop a track assembly, allowing the operator to turn the machine 360-degrees. A large articulated arm with a digging shovel, sometimes called a bucket, digs with a motion that pulls material back toward the machine. Machines of this type, with the opening of the bucket pointing upward, that dig with a motion that pushes the bucket away from the cab are known as power shovels.
Very large surface mining operations may employ gigantic machines such as the bucket wheel mining excavator. These machines usually remove overburden, surface material that covers more valuable, mineral-rich ores underneath. A large, self-propelled, tracked vehicle has a long arm called a boom mounted on it that ends with a large rotating wheel outfitted with several buckets. As the wheel turns, the buckets dig into the earth and then dump their payloads onto a conveyor belt for transport to other vehicles for removal before the wheel rotates them around to dig again.
Extremely large power shovels called dragline shovels are another type of mining excavator. These huge machines have a shovel that is suspended from a boom by a series of chains or cables, which are also used to control the motion of the shovel and its digging operations. Some dragline excavators are capable of scooping more than 50 cubic meters per shovel and use so much power that they may be connected directly to the electrical power grid.