Mineral impurities, problems caused

In addition to these problems, contaminants within the fuel can also cause air pollution. The most common and worrisome impurity in fossil fuels is sulphur (S), partly present as the mineral pyrite, FeS2. There may be as much as 6% sulphur in some coals and this is converted to S02 on combustion ... 

Barite is frequently contaminated with alkaline-soluble carbonate and sulfide minerals that cause serious drilling fluid problems. Therefore, small concentrations of impurities in barite can lead to significant contamination of the drilling fluid. ... 

The purity of a filler is of importance both commercially and technically, i.e., the users need to know what they are buying, whether it contains components that may be detrimental to the properties of their product and whether it will cause environmental problems. Impurities include trace elements that may be on the filler surface or in the strnctnre of the filler and ancillary minerals, which will have been formed at the same... 

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