Ore dressing


Ore dressing

Ore dressing is one of the principal processes in the work of mining. It consists of separating economically valuable minerals from those with little or no value, or of separating valuable minerals from each other, so that they may be further processed, for example by smelting.

Purpose

When minerals are brought up from the mine to the surface, they commonly contain a variety of materials. The contained metal may be either in the native uncombined state or a chemical compound (commonly sulfides or oxides of metals), but in either case the valuable mineral ore is always associated with minerals of little or no value (gangue). The province of the ore-dresser is to separate the valuables from the waste, for example, quartz, feldspar, or calcite, by mechanical means, obtaining thereby concentrates and tailings. It is then the province of the metallurgist is to extract the pure metal from the concentrates by chemical means, with or without the aid of heat.

There are also a number of non-metallic minerals which do not have any value, or at best do not reach their highest value until they have been subjected to some form of mechanical preparation; among them are diamonds, graphite, corundum, garnet, asbestos, and coal.

Methods

Ore commonly has to be crushed, so that crystals of different minerals adhering to each other are broken apart. These then have to be separated. The crushing process is known as "spalling".

Crushing

Traditionally, the raw mineral was broken up using hammers, wielded by hand. Later mechanical means were found to achieve this. An early example of this was the Cornish stamp, consisting of a series of iron hammers mounted in a vertical frame, raised by cams on the shaft of a waterwheel and falling on to the ore under gravity. These have been replaced by other machinery.

eparation

The simplest method of separating ore from gangue consists of the picking out the individual crystals of each. However this is a very tedious process, particularly when the individual particles are small.

Another comparatively simple method relies on the various minerals having different densities, causing them to collect in different places: metallic minerals (being heavier) will drop out of suspension more quickly than lighter ones, which will be carried further by a stream of water (or other liquid). One variety of apparatus for this is the 'buddle'.

Alternatively, if a fluid of a suitable density can be provided, lighter minerals will float and heavier ones sink. This is known as floatation.

Glossary of ore dressing terms

These definitions are from Chambers Twentieth Century Dictionary: [Chambers Twentieth Century Dictionary, 1972, ISBN 0 550 10206 X]
* Buddle,
** (noun), an inclined hutch for washing ore
** (verb), to wash with a buddle
* Hutch (noun), a trough used with some ore-dressing machines
* Keeve or kieve (noun), a large tub
* Spale (noun), a splinter or chip (Scottish)
* Spall,
** (noun), a chip or splinter, especially of stone
** (verb), to split, splinter or chip

References

ources

* Various articles in J. Day & R. F. Tylecote, "Metals in the Industrial Revolution" (Institute of Metals, London 1991).


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Look at other dictionaries:

  • ore dressing — noun crushing and separating ore into valuable substances or waste by any of a variety of techniques • Syn: ↑mineral extraction, ↑mineral processing, ↑mineral dressing, ↑ore processing, ↑beneficiation • Derivationally related forms: ↑beneficiate …   Useful english dictionary

  • ore dressing — noun Date: 1831 mechanical preparation (as by crushing) and concentration (as by flotation) of ore …   New Collegiate Dictionary

  • ore dressing — n. Metall. the mechanical processes by which valuable minerals are separated from ore. [1860 65] * * * …   Universalium

  • ore dressing — noun Any treatment of an ore used to concentrate its valuable constituents (minerals) into products (concentrate) of smaller bulk, and simultaneously to collect the worthless material (gangue) into discardable waste ( …   Wiktionary

  • ore dressing — /ˈɔ drɛsɪŋ/ (say aw dresing) noun the art of separating the valuable minerals from an ore without chemical changes …   Australian English dictionary

  • Dressing — may refer to: Dressing (medical), a medical covering for a wound, usually made of cloth Ore dressing Salad dressing, a type of sauce which is generally poured on a salad, or spread on the bread of a sandwich Stuffing, a mixture of various… …   Wikipedia

  • ore — /awr, ohr/, n. 1. a metal bearing mineral or rock, or a native metal, that can be mined at a profit. 2. a mineral or natural product serving as a source of some nonmetallic substance, as sulfur. [bef. 900; conflation of ME ore, OE ora ore,… …   Universalium

  • öre — /ue rddeuh/, n., pl. öre. 1. a bronze coin of Norway, the 100th part of a krone. 2. a zinc or bronze coin of Denmark, the 100th part of a krone. 3. a bronze coin of Sweden, the 100th part of a krona. 4. a fractional currency of the Faeroe Islands …   Universalium

  • ore processing — noun crushing and separating ore into valuable substances or waste by any of a variety of techniques • Syn: ↑mineral extraction, ↑mineral processing, ↑mineral dressing, ↑ore dressing, ↑beneficiation • Derivationally related forms: ↑beneficiate …   Useful english dictionary

  • dressing floor — /ˈdrɛsɪŋ flɔ/ (say dresing flaw) noun the place where ore is sorted on the floor of a mine; a strake …   Australian English dictionary


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