Mine Hoist

a set of machines and devices that are used to raise or lower personnel and loads in vertical or inclined shafts.

A mine hoist (Figure 1) includes a hoisting machine, hoist cables, receptacles, and sheaves; the sheaves are mounted on the

Figure 1. Diagram of a mine hoist: (1) hoisting machine, (2) hoist cables, (3) skips, (4) sheaves, (5) headframe, (6) loading chute, (7) bin

headframe. Useful minerals are loaded into the receptacles by means of a loading chute and are discharged into a bin. The hoisting machine (Figure 2) comprises a winding drum or driving sheave, a brake, reduction gears, an electric motor, and a control console.

Depending on their purpose, various types of mine hoists are distinguished. Main hoists are used to raise useful minerals and barren rock to the surface. Auxiliary hoists are employed to raise or lower personnel and various loads. Sinking hoists are used in the sinking or deepening of shafts. Inspection or emergency hoists are employed to inspect shafts or to raise personnel in emergencies.

Figure 2. A hoisting machine with a cylindrical drum: (1) winding drum, (2) brake, (3) reduction gears, (4) electric motor, (5) control console

The receptacles used in mine hoists may be cages, skips, or buckets. Depending on whether or how the weight of the hoist cables is balanced, the hoisting may be unbalanced, statically balanced, or dynamically balanced. The winding drum or driving sheave may have a single radius or a large and a small radius. Cylindrical drums and Koepe sheaves have a single radius; bicylindroconical drums have a large and a small radius.

Electric motors with an output of up to 5,000 or more kilowatts (kW) are used in hoisting machines. AC induction motors are widely employed. The output of such motors is 1,800–2,000 kW for skip hoists or 800–1,000 kW for hoists that raise and lower cages. DC motors are usually employed in high-capacity hoists.

From the viewpoint of engineering and economy, the best maximum cable speeds range up to 20 m/sec for hoisting loads and up to 12 m/sec for hoisting personnel.

Multirope friction winders are promising. Such hoisting machines are tower mounted over shafts and are used to hoist two skips or two cages or to hoist a single receptacle balanced by a counterweight. In particular, hoists driven by multirope friction winders are used to service several levels at the same time.