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Nowadays the demands to the quality of coal as a fuel are growing more and more. Sulphur is the impurity in coals.
Average content of sulphur in coal’s storage of “Kurakhovskaya” mine changes from 1.6 % (stratum l4) to 5.6 % (stratum l12). On the average it is 3.6 %.
The distribution of common sulphur on the fields is not regular. That’s why it is impossible to produce industrial selective getting of lowsulphur coals.
Content of organic sulphur in middlesulphur coals is less by 0.8 – 0.2 % than in highsulphur ones. The difference is conditioned by the pyrite sulphur, because its content in highsulphur coals is more by 1.19 – 3.9 % than in middlesulphur coals. Pyrite variety (Spd – 51.4 – 87.8 %) prevails in the composition of common sulphur. It is represented by pyrite in the form of lens, nests, inclusions and also by deposits and films on the walls of the cracks.
Separation of pyrite from the coal is an important factor for increasing the quality of the coals is the separation of pyrite from it. Besides pyrite can be used for the production of sulphuric acid.
Studying and estimation of pyrite is performed in coal cleaning.
According to the studying of coals the percentage of sulphur in the concentrate is 54 – 60 % (specific gravity 1.4 gr/c3), 48 % (specific gravity 1.5 gr/c3), and the percentage of sulphur in the rock is 31 %.
According to the laboratory investigations the content of sulphur in concentrate of power coals with specific gravity 1.4 – 1.5 gr/c3 is from 1.8 – 2.9 % to 1.8 – 3.2 %. On the average it is 2.5 – 2.6 %; 4.8 – 5.0 %. As to the rocks it is from 2 to 12 % and on the average it is 6.1 %.
An average level of content of sulphur in the concentrate of power coals exceeds the level under which is possible the formation of toxic compounds. An average level of sulphur in industrial product exceeds the levels by 2.4 – 2.5 times and in rocks in 3 times.
Maximum content of sulphur in the concentrate with specific gravity 1.4 – 1.5 gr/c3 exceeds the limit by 1.6 times in industrial product from 3.8 to 4 times and in rock by 6 times.
It is necessary to take into account the high level of sulphur in products and waste of coal cleaning during its using, reclamation and storage.
Proceed from above stated, it is necessary to make counts of reserves of “extracting” pyrite which are isolated to the tailings during the coal cleaning. The reserves of pyrite are counted only in a group of balance reserves and are recounted in conventional pyrite.
The reserves are counted in terms of coal’s reserves and average contents of conventional pyrite.
The reserves of conventional pyrite is taking into account accurate withing in 0.1 th/t. Count is made in units or in enlarging units.
The high content of pyrite in coals is the source of formation of sulphur gas and corrosion substances which influence on surroundings negatively. Separation of pyrite during coal refining will improve the state of surrounding, will raise the quality of coal and pyrite may become a raw material for sulphide industry.
LITERATURE