Question

the two steps acid treatments for the demineralization of coal are

Answer 1

A coal product which exceeds the purity requirements for ash, iron and silicon in Hall Cell anode carbon was prepared by a unique leaching sequence involving caustic treatment, followed by treatments with sulphuric and nitric acids. The two acid leaching steps for the three-step process can also be combined with no adverse effect on the coal quality for anode purposes. In the process, the majority of the pyrite reacts with NaOH, forming Fe2O3 and Na2S. Na2S is dissolved in the leaching liquor and Fe2O3 is trapped in the coal matrix. The incorporation of sodium with organic sulphur increases the ash content and decreases the heating value of caustic leached coal on a dry basis. The silicon and aluminium contents are lowered by reactions with NaOH. While most of the reaction products are soluble sodium silicates and aluminates, the remaining silica and alumina form noselite. Dilute sulphuric acid dissolves nearly all of the sodium salts. The remaining iron compounds are dissolved by nitric acid.

Answer 2

Answer:

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