Pyrite separation processes

A simple cleaning process developed by University of Kentucky (Parekh, 2003) begins with the pulverization of coal in a rotating attritor down to 10 (im dimensions. Surfactants and oils are used to separate the purified coal particles from the heavier solid inclusions of silicates, alumino-silicates and iron pyrite. The process produces an acceptable level of ash at a total energy degradation of 1%-primarily associated with the electric attritor that consumes 0.33 MJ-th/kg-C (65 kWh/ton). The cost (raw coal plus cleaning) is estimated at 60/ton. 

Biological processes are also being studied to investigate abiHty to remove sulfur species in order to remove potential contributors to acid rain (see Air pollution). These species include benzothiophene-type materials, which are the most difficult to remove chemically, as weU as pyritic material. The pyrite may be treated to enhance the abiHty of flotation processes to separate the mineral from the combustible parts of the coal. Genetic engineering (qv) techniques are being appHed to develop more effective species. 

Several other processes for extracting Be from beryl have been patented the most feasible involves the formation of BeCl2 by direct chlorination of beryl under reducing conditions several volatile chlorides are produced by this reaction (BeCl2, AICI3, SiCl4 and FeClj) and are separated by fractional condensation to give the product in a pure state. Other methods involve the fusion of beryl with carbon and pyrites, with calcium carbide and with silicon. 

Magnex A process for removing mineral matter from coal by first rendering it magnetic. The coal is treated with iron carbonyl vapor, which deposits a thin skin of magnetic material on the pyrite and other mineral matter, but not on the coal. Conventional magnetic separation is then used. Developed by Hazen Research in 1976. 

Separation of arsenopyrite and pyrite is important from the point of view of reducing downstream processing costs. Normally, roasting or pressure oxidation followed by cya-nidation is used to recover gold. 

The goal of beneficiation is to remove as much sulfur from a fuel as possible before it is ever burned. When burned, fuel with lower sulfur content will produce less sulfur dioxide. Beneficiation is usually accomplished by a physical process that separates one form of sulfur, pyritic sulfur, from coal. Pyritic sulfur consists of sulfur minerals (primarily sulfides) that are not chemically bonded to coal in any way. The name is taken from the most common form of mineral sulfur usually found in coal, pyrite, or iron sulfide (FeS2). 

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