underground mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...

a hoist or winder is used to raise and lower

conveyances In law, conveyancing is the transfer of legal title of real property from one person to another, or the granting of an encumbrance such as a mortgage or a lien. A typical conveyancing transaction has two major phases: the exchange of contracts ...

within the mine shaft. Modern hoists are normally powered using electric motors, historically with

direct current Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or eve ...

drives utilizing Ward Leonard control machines and later solid-state converters ( thyristors), however modern large hoists use

alternating current Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in which ...

drives that are variable frequency controlled. There are three principal types of hoists used in mining applications:

Drum hoist

Drum hoists are the most common type of hoist used in North America,

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring count ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the souther ...

. When using a drum hoist the hoisting cable is wound around the drum when the conveyance is lifted. Single-drum hoists can be used in smaller applications, however double-drum hoists easily allow the hoisting of two conveyances in balance (i.e. one skip being lifted while a second skip is being lowered). Drum hoists are mounted on concrete slabs within a hoistroom, the hoisting ropes run from the drum, up to the top of the

headframe A headframe (also known as a gallows frame, winding tower, hoist frame,Ernst, Dr.-Ing. Richard (1989). ''Wörterbuch der Industriellen Technik'' (5th ed.). Wiesbaden: Oscar Brandstetter, 1989. pit frame, shafthead frame, headgear, headstock o ...

, over a sheave wheel and down where they connect to the conveyance (cage or skip).

Advantages

Drum hoists require less routine maintenance than a friction hoist, because the haulage cable is fixed to the drum, and therefore have less

downtime The term downtime is used to refer to periods when a system is unavailable. The unavailability is the proportion of a time-span that a system is unavailable or offline. This is usually a result of the system failing to function because of an ...

, and the maintenance regime is less sophisticated. Drum hoists can continue to operate if the shaft bottom gets flooded and less shaft depth is required below the loading pocket, unlike friction hoists where such flooding could cover the tail ropes and so on. Because drum hoists do not have tail ropes, the hoisting system is more suited to

sling sling may refer to: Places *Sling, Anglesey, Wales *Sling, Gloucestershire, England, a small village in the Forest of Dean People with the name * Otto Šling (1912–1952), repressed Czech communist functionary Arts, entertainment, and media * ...

ing beneath a conveyance.

Disadvantages

Drum hoists take up more space than a friction hoist for the same service as all of the haulage cable must be accommodated on the drum when the hoist is fully raised. Drum hoists require rapid fluctuations in power demand, which can pose a problem if power is generated on site rather than provided through the main

power grid An electrical grid is an interconnected network for electricity delivery from producers to consumers. Electrical grids vary in size and can cover whole countries or continents. It consists of:Kaplan, S. M. (2009). Smart Grid. Electrical Power ...

Friction hoist

Friction (or Koepe) hoists are the most common type of hoist used in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an ...

and Australia. The friction hoist was invented in 1877 by Frederick Koepe. Friction hoists are mounted on the ground above the mine shaft, or at the top of the headframe. Friction hoists utilize tail ropes and

counterweight A counterweight is a weight that, by applying an opposite force, provides balance and stability of a mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves energy and causes less wea ...

s and do not have the haulage rope fixed to the wheel, but instead passed around it. The tailropes and weights offset the need for the motor to overcome the weight of the conveyance and hoisting rope, thereby reducing the required

horsepower Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are th ...

of the hoisting motor by up to 30%, with the overall power consumption remaining the same. Friction hoists, unlike drum hoists, can and normally do use multiple ropes giving them a larger payload capacity, however since they require a larger safety factor, they are impractical for very deep shafts.

Advantages

New friction hoists are less expensive than new drum hoists, and the

lead time A lead time is the latency between the initiation and completion of a process. For example, the lead time between the placement of an order and delivery of new cars by a given manufacturer might be between 2 weeks and 6 months, depending on vari ...

for delivery may be shorter as there is more competition for manufacturing. Multi-rope friction hoists have a larger lift capacity than a drum hoist. A friction hoist is smaller in diameter than a drum hoist for the same service, making it easier to ship and install than a drum hoist.

Disadvantages

Balanced friction hoists are not suitable for hoisting from multiple loading pockets on different horizons within a shaft, and are generally not suitable for deep shafts. Friction hoists can not operate at normal speeds if the shaft bottom is flooded and water reaches the tail ropes.

Blair multi-rope hoist

The Blair multi-rope hoist is a variation of the double-drum hoist. It is used in extremely deep shafts as the second drums cable are used to balance the primary load.

Examples of hoists

File:Ein-trommelförderung.svg, Single-drum hoist File:Doppel-trommelförderung.svg, Double-drum hoist File:Treibscheiben-Förderung.svg, Friction (Koepe) hoist File:Blair-trommelförderung.svg, Blair-multi rope hoist File:Konische Trommelförderung.svg, Conical drum File:Spiral-trommelförderung.svg, Spiral drum

Footnotes

{{Mining technology Underground mining Vertical transport devices Winches

Drum hoist

Advantages

Disadvantages

Friction hoist

Advantages

Disadvantages

Blair multi-rope hoist

Examples of hoists

See also

Footnotes