GB1580098A

GB1580098A - Method of separating some of the sulphur contained in coal

Info

Publication number: GB1580098A
Application number: GB52269/77A
Authority: GB
Original assignee: L&C Steinmueller GmbH
Current assignee: Hitachi Zosen Inova Steinmueller GmbH
Priority date: 1976-12-31
Filing date: 1977-12-15
Publication date: 1980-11-26
Also published as: DE2659759A1; ZA777456B; JPS5385801A; FR2375907A1; AU3189077A

Description

(54) METHOD OF SEPARATING SOME OF THE SULPHUR CONTAINED IN COAL (71) We, L. & C. STEINMULLER GmbH, a German Company, of 527 Gummersbach, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a method of separating some of the sulphur contained in coal.

The operators of power stations for the production of current, and also of steam generators for the production of process steam or the like, and other large firing plants have to pay attention to regulations for keeping the air clean, that is to say the flue gases emerging from their firing plants into the atmosphere must not exceed certain emission values. This includes the emission of sulphur dioxide, which may be particularly high when coal is burnt.

In the Ruhr region, the average sulphur content of the coal mined there amounts to about 1.1%. In other coals, however, it may reach up to 6% and more.

Various cleaning methods have been proposed in crder to adhere to the emission values predetermined by regulations. One group of these methods is concerned with the desulphurization of flue gas, that is to say the removal of the sulphur is effected from the flue gases after the combustion of the coal. With these methods, additional environmental problems arise because, with them, gypsum is generally produced which can only be utilized in limited quantities - if at all - by the relevant industry.

Methods have also been proposed for gasifying the coal completely, then desulphurizing the gas and supplying it as purified gas to the firing points.

According to other proposals, the desulphurization of the coal ground into dust is effected before combustion by rapid carbonization and/or partial gasification, in which case the gas formed is burnt, after purification together with the coke dust formed, which is low in sulphur. The degree of partial gasification depends, for example, on the sulphur still contained in the coke dust.

Proposals are also known for subjecting the coal to flotation after mining, so as to remove the sulphur from the coal as far as possible in this manner. Flotation installations for the whole amount of coal require extremely high investment costs, however.

The object of the present invention is to indicate a method which renders possible the separation of some of the sulphur contained in coal under economically more favourable conditions.

According to the present invention there is provided a method of separating some of the sulphur contained in coal, characterised by the following method steps: a) the coal is ground to gain sizes less than 0.2 mm; b) the grain fractions from 0.04 to 0.06 mm are separated out of the ground coal dust; c) the aforesaid separated out grain fractions are subjected to a sulphur extraction process which separates sulphur from the coal; d) the separated sulphur component is removed from the coal component for further utilisation separately.

Preferably, the grain fractions from 0.03 to 0.07 are separated out of the ground coal dust and subjected to the sulphur extraction process.

Extensive examination of various types of coal during the development of the rapid carbonization and/or partial gasification method, wherein coal dust < 0.2 mm, preferably < 0.1 mm, is processed, has shown that during the grinding operation of the coal, an effect can be observed which is favourable to the separation of some of the sulphur from the coal. During the examination of the individual grain fractions in the range between 0 and 0.2 mm, it is found that, particularly with coals having a relatively high sulphur content, predominantly the pyrites accumulate in a specific grain fraction, which is apparently caused by the different grinding characteristics - sulphur component/pure grain substance.The sulphur content of the grain fraction between 0.03 mm and 0.07 mm, generally in the grain fraction between 0.04 mm and 0.06 mm, is up to three or four times higher than in the other fractions.

Thus there is the possibility of removing a considerable proportion of the total sulphur from the coal by subjecting this grain fraction to a sulphur extraction process, such as for example the flotation process.

After flotation, or the like, possibly after previous further grinding, the pure coal substance residue of this fraction, freed of sulphur, can be returned to the other grain fractions, the sulphur can be supplied for further processing or storage.

Thus it is possible, by treating only some of the ground coal, with less expense on apparatus and so lower costs, to reduce the sulphur content in the coal dust to be processed to such an extent that the flue gases resulting during the combustion of the coal no longer need to be desulphurized.

WHAT WE CLAIM IS: 1. A method of separating some of the sulphur contained in coal, characterised by the following method steps: a) the coal is ground to grain sizes less than 0.2 mm; b) the grain fractions from 0.04 to 0.06 mm are separated out of the ground coal dust; c) the aforesaid separated out grain fractions are subjected to a sulphur extraction process which separates sulphur from the coal; d) the separated sulphur component is removed from the coal component for further utilisation separately.

2. A method as claimed in claim 1, wherein the grain fractions from 0.03 to 0.07 are separated out of the ground coal dust and subjected to the sulphur extraction process.

3. A method as claimed in claim 1 or 2, wherein the coal from which sulphur was extracted in said process is mixed with the remainder of the coal.

4. A method of separating some of the sulphur contained in coal, as claimed in claim 1 and substantially as hereinbefore described.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. favourable to the separation of some of the sulphur from the coal. During the examination of the individual grain fractions in the range between 0 and 0.2 mm, it is found that, particularly with coals having a relatively high sulphur content, predominantly the pyrites accumulate in a specific grain fraction, which is apparently caused by the different grinding characteristics - sulphur component/pure grain substance. The sulphur content of the grain fraction between 0.03 mm and 0.07 mm, generally in the grain fraction between 0.04 mm and 0.06 mm, is up to three or four times higher than in the other fractions. Thus there is the possibility of removing a considerable proportion of the total sulphur from the coal by subjecting this grain fraction to a sulphur extraction process, such as for example the flotation process. After flotation, or the like, possibly after previous further grinding, the pure coal substance residue of this fraction, freed of sulphur, can be returned to the other grain fractions, the sulphur can be supplied for further processing or storage. Thus it is possible, by treating only some of the ground coal, with less expense on apparatus and so lower costs, to reduce the sulphur content in the coal dust to be processed to such an extent that the flue gases resulting during the combustion of the coal no longer need to be desulphurized. WHAT WE CLAIM IS:

1. A method of separating some of the sulphur contained in coal, characterised by the following method steps: a) the coal is ground to grain sizes less than 0.2 mm; b) the grain fractions from 0.04 to 0.06 mm are separated out of the ground coal dust; c) the aforesaid separated out grain fractions are subjected to a sulphur extraction process which separates sulphur from the coal; d) the separated sulphur component is removed from the coal component for further utilisation separately.