Gravity concentration and its early use
Introduction of Gravity concentration
In beneficiation plant, Gravity concentration
is a process in which particles of mixed sizes, shapes, and specific gravities
are separated from each other in a fluid by the force of gravity or by
centrifugal force. The process is designed to separate particles by specific
gravity, but to a certain extent it also separates particles on the basis of
size and shape.
Historically,
the process has been used to separate ore minerals or coal from their
associated gangue (refuse) on the basis of mineral density (Table 1). Gravity
concentration is often equally applicable to other common industrial processes,
such as degritting food grains, paper pulp, and chemical raw materials;
recycling municipal solid waste; recovering and recycling spills, splatters,
skimmings, skulls, turnings, and grindings from metal production and
fabrication; and remediating toxic waste piles.
Early Use and Development of Gravity
Concentration
Gravity
concentration of heavy minerals is a natural geological process, and Mother
Nature has concentrated minerals, such as gold, cassiterite, ilmenite, and
diamonds, into natural placer (alluvial or glacial) deposits. Humans have used
gravity concentration processes for thousands of years. Egyptian monuments of
about 3000 BCE depict the washing of gold ores and the
Athenians undoubtedly used flowing film concentration to process ores from
their mines at Laurium before the birth of Christ . In the sixteenth century,
Agricola in De Re
Metallica described
several gravity concentration devices used in Europe, and seventeenth-century
Chinese concentration technology is described in T’ien-kung K’ai-Wu. In the nineteenth century, Rittinger in Europe
performed theoretical and practical studies, and in the later part of that
century, Richards in the United States did much to establish the basic
principles of gravity concentration that were published in his classic
fourvolume treatise. In the 1920s, Finkey established many of the mathematical relationships
describing the process and codified the principles on which gravity
concentration is based. Other valuable references that describe either
processes or devices are Richards and Locke, Mills, Burt and Mills, Aplan ,
Weiss, Osborne, and Leonard and Hardinge.
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