The operation of building a pile is called “stacking,” and removing and relocating operations are called “reclaiming.” Stackers and reclaimers are specialized for their respective operations, but a stacker-reclaimer is capable of handling both. This system is indispensable at ironworks, power plants, ports, and mines.

A stacker is a large machine used in bulk material handling. Its function is to pile bulk material such as limestone, ores, coal and cereals on to a stockpile. A reclaimer can be used to recover the material. Stackers are nominally rated for capacity in tones per hour (tph). They normally travel on a rail between stockpiles in the stockyard. A stacker can usually move in at least two directions: horizontally along the rail and vertically by luffing (raising and lowering) its boom. Luffing of the boom minimizes dust by reducing the distance that material such as coal needs to fall to the top of the stockpile. The boom is luffed upwards as the height of the stockpile increases. Some stackers can rotate the boom. This allows a single stacker to form two stockpiles, one on either side of the conveyor.

A reclaimer is a large machine used in bulk material handling applications. A reclaimer's function is to recover bulk material such as ores and cereals from a stockpile. A stacker is used to stack the material. Reclaimers are volumetric machines and are rated in m3/h (cubic meters per hour) for capacity, which is often converted to t/h (tones per hour) based on the average bulk density of the material being reclaimed. Reclaimers normally travel on a rail between stockpiles in the stockyard. A bucket wheel reclaimer can typically move in three directions: horizontally along the rail; vertically by "luffing" its boom and rotationally by slewing its boom. Reclaimers are generally electrically powered by means of a trailing cable.

Component:
Bucket wheel and chute
In reclaiming operations, the bucket disposed at the boom end digs up material and drops it onto a slanted board (“chute”) designed for material to slide down to the conveyor. In this system, eight buckets are attached to a wheel six meters in diameter. In a single rotation, the bucket wheel is estimated to dig up two tons of material.
Boom
Material flows by way of the boom - the “main street” of the system - for stacking and reclaiming. The conveyor inside the square framework travels in a loop in order to transport material. For reclaiming, the system drops material from the center of the portal onto the conveyor that runs on the ground between two rails.
Counterweight and winch
There are two ways to keep the boom in place and to raise/lower it: one is to suspend the boom with a rope and move it using an electric winch; and another is to install a luffing cylinder at the base of the boom. To control the boom’s movement, a huge counterweight is installed. The counterweight (a concrete-filled can) weighs 100 tons.
Portal and tower
A cylinder located at the lower part of the equipment is called the “portal.” It holds the entire unit and serves as the “pivot.” The portal has two motors that allow it to swing the boom in an arc of ±145°. The tower on top of the portal serves as an axis to maintain balance among the components of the system. The winch and the operation room are on the tower.
Tripper
The tripper conveys materials brought from another location up to the boom for stacking. Some trippers are equipped with derricks to raise/lower them.

Automated operations to save manpower involved in stacking and reclaiming. Accurate detection of pile edges during reclaiming operations to enable the equipment to operate in response to its changes is key technology for automating operations. Using ultrasonic sensors technology for detecting pile edges, and moreover, for determining the location where reclaiming should begin.

#manufacturing
#materialhandling
#coal

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