Pyrite roaster

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Sulfur dioxide is manufactured mostly by combustion of sulfur or its iron sulfide mineral, pyrite, FeS2, in air. The flame temperatures for such combustion of sulfur in the air are usually in the range 1,200 to 1,600°C. Many types of sulfur burners are available and are used to produce sulfur dioxide. They include rotary-kiln, spray, spinning-cup and air-atomizing sulfur burners. Selection and design of burners depend on quality of sulfur to be burned, and rate and concentration of sulfur dioxide to be generated. Pyrites or other metal sulfides may be burned in air in fluid-bed roasters to form sulfur dioxide. 

A series of industrial roasters in Wanshan recover mercury from extremely low-grade ores ( 0.06% Hg). Later, the roasters are adapted for processing low-grade Guizhou pyrite for sulfuric acid manufacture. 

Whilst we are dealing with this subject, we may point out that in the case of open roasters it may become necessary to consider the ingredients which are contained in the fire gases thus, coal which is rich in pyrites would not be suitable in operations in which the sulphurous acid produced would act on the substances operated on. Where such is the case, coke as free from sulphur as possible should be used, or better still a gaseous fuel. In the latter case the furnace will have to be constructed in such a manner that, instead of having a fireplace which is fed with solid fuel, it has a chamber arranged for the combustion of gas. 

Pyrite ores are roasted in fluidized beds. The gases from the roasters can contain dust, unbumt particles, etc., and hence are cleaned by using cyclones, bag filters, and electrostatic precipitators. 

As the sulfide ores (pyrites) are roasted, the roaster gas and the metal oxides produced are separated from each other in cyclones. 

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