A Knelson concentrator is a type of gravity concentration apparatus, predominantly used in the
gold mining
Gold mining is the extraction of gold resources by mining. Historically, mining gold from alluvial deposits used manual separation processes, such as gold panning. However, with the expansion of gold mining to ores that are not on the surfac ...
industry. It is used for the recovery of fine particles of free gold, meaning gold that does not require
gold cyanidation
Gold cyanidation (also known as the cyanide process or the MacArthur-Forrest process) is a hydrometallurgical technique for extracting gold from low-grade ore by converting the gold to a water-soluble coordination complex. It is the most commonl ...
for recovery.
Operation
The machines utilise the principles of a
centrifuge
A centrifuge is a device that uses centrifugal force to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby separating fluids of different densities (e.g. cream from milk) or ...
to enhance the gravitational force experienced by feed particles to effect separation based on particle density. The key components of the unit are a cone shaped "concentrate" bowl, rotated at high speed by an electric motor and a pressurized water jacket encompassing the bowl. Feed material, typically from a ball mill discharge or cyclone underflow bleed, is fed as a slurry toward the centre of the bowl from above. The feed slurry contacts the base plate of the vessel and, due to its rotation, is thrust outward. The outer extremities of the concentrate bowl house a series of ribs and between each pair of ribs is a groove. During operation the lighter material flows upward over the grooves and heavy mineral particles (usually of economic value) become trapped within them. Pressurized water is injected through a series of tangential water inlets along the perimeter of each groove to maintain a fluidized bed of particles in which heavy mineral particles can be efficiently concentrated. The Knelson concentrator typically operates as a batch process, with lighter
gangue
In mining, gangue () is the commercially worthless material that surrounds, or is closely mixed with, a wanted mineral in an ore deposit. It is thus distinct from overburden, which is the waste rock or materials overlying an ore or mineral body ...
material being continuously discharged via overflow and a heavy mineral concentrate periodically removed by flushing the bowl with water.
History
The first Knelson concentrator was developed by Byron Knelson in 1980.
Mines
Knelson concentrators are used in a number of gold mines operated by
AngloGold Ashanti
AngloGold Ashanti Limited is a global gold mining company. It was formed in 2004 by the merger of AngloGold and the Ashanti Goldfields Corporation. It is now a global gold producer with 21 operations on four continents. The company is listed ...
, like
Geita
Geita is a town and regional capital of Geita Region in northwestern Tanzania. The town is known for its gold trade. Geita, with a population of 99,795 (2012 census). It is located in the centre of a gold mining area. In March 2012 it became th ...
,
Sunrise Dam and the
Serra Grande Gold Mine
The Serra Grande Gold Mine is a gold mine located 5 km from Crixás, in the Goiás state of Brazil. It is jointly owned by AngloGold Ashanti and Kinross Gold Corporation Kinross Gold Corporation is a Canadian-based gold and silver mining ...
as well as
Barrick's TGO Tomingley Gold Operation
Bulyanhulu Gold Mine
Bulyanhulu Gold Mine is an underground gold mine in the Shinyanga Region of Tanzania, located 55 kilometres south of Lake Victoria. It is one of three gold mines owned by Acacia Mining plc, formerly African Barrick Gold plc, a company owned by Ba ...
.
Testimonials
Knelson website, accessed: 2 August 2010
References
External links
Knelson website
Gold Metallurgy website
{{Extractive metallurgy
Centrifuges
Mining equipment
Gold mining