US2369024A - Process of treating coal and composition therefor - Google Patents

Description

Patented Feb. 6, 1945 PROCESS OF TREATING COAL AND COMPOSITION THEREFOR Lawrence P; Crecelius, Shaker Heights, Ohio, as

Signor to The Coal Processing Company, Cleveland, Ohio, a corporation of Ohio V No Drawing. Application September 5, 1941,

Serial No. 409,659

2 Claims.

This invention relates to a process for the treating of coal and the burning of the'same, which coal contains relatively large amounts of iron sulphur compounds, such as iron pyrites, for the purpose of improving the burning of the coaLobviating the efiect of deleterious flue gases and tube slagging, and to improve the ash characteristics. I

The present invention may be properly considered in the nature of an improvement upon the invention which is set forth in my issued Patent No. 2,089,599, granted August 10, 1937.

In that patent I described the advance in the art of power production in power plants which was signalized by the much higher rates of burn ing of coal in furnaces than had heretofore been the practice and the accompanying relative diminution of air supply, and I further, in the before mentioned patent, pointed out the fact that the change in the art of power production b the higher rates of burning of coal in furnaces has had the effect of disqualifying and eliminatingto a very large extent the use of coals high in iron sulphur compounds due to the fact that such coals, when subjected to the furnace conditions which had been described, break down and melt the iron sulphur compounds at approximately 2140 F., causing same to run down upon the grate surfaces of the furnace, obstructing the passage of air and fusing upon the iron of the grate parts.

In my former patent I pointed out how it was possible to utilize chlorine, present during the burning of the coal, for the purpose of effecting, at furnace temperatures, a decomposition of the iron sulphur compounds and ultimately form a stable compound of both iron and sulphur, towit, ferric oxide and sulphur'dioxide.

In my prior patent the desired result was accomplished by treating the coal with a composition comprising a suitable deliquescent halogen compound, such as calcium chloride or magnesium chloride or mixtures of the two, together with suitable catalytic material such as manganese dioxide, iron oxide, chromic oxide, using two or more of them together, and I specifically pointed out a composition suitable for the treatment of coal as consisting of Percent by weight Calcium chloride 92 Potassium dichromate 3 Manganese dioxide 3 Tannic acid 2 This composition was designed to be mixed with water which was sprayed upon the coal, so

as to be distributed throughout themass of coal, either at the mine or at some time prior to the introduction of the coal into the furnaca therein to be burned. V v v a V The present invention differs from the invention pointed out in mypatent to which reference has been made in that adifferent composition of material is used to be applied to the coal, for the same fundamental purposes as that described in my former patent, except that some additional advantages .are gained by the use of the new composition which will be subsequently. pointed out. 4

It may be here stated thatin connection with the present invention the compositiomto be presently described, is mixed with water and sprayed uponthe coal, either at the mine orat any time prior to the coalbeing introduced into the fur nace in which it is to be burned. Experience has indicated that the quantityof the composition to be used is approximately five per cent (5%) of the sulphur content of the coal which is to be burned.

Speaking in general terms, the materials used in connection with the present invention may be said to comprise a suitable deliquescent halogen compound, such for instance as calcium chloride or magnesium chloride or mixtures of the two, together with suitable catalytic .material such as chromic oxide and manganese dioxide, either one of which may be used, but the catalytic effect is enhanced very materially by the use of both chromium oxide and manganese dioxide. In addition, dextrin is employed and potassium acid fluoride.

One suitable composition for the purpose is made up as follows:

Percent by weight Calcium chloride- 92 Chromic oxide 3 Manganese dioxide 3 Dextrin 1 Potassium acid fluoride 1 Ihe chemical response in connection with the use of calcium chloride, manganese dioxide, and

chromic oxide, when utilized in connection with the burning of coal high in compounds of iron and sulphur, is the same as that which has been described in my prior Patent No. 2,089,599.

While in my prior patent the suitable composition therein mentioned included potassium di-v chromate, the subsequent description :r'n'ade it In the present invention, the use of dextrln is desired because of its colloidal property when mixed with water and therefore when the metallic oxides of manganese and chromium (in finely divided condition) are mixed with water in which dextrin is present, the colloidal characteristic: of the dextrin maintains the metallic oxides in suspension in the liquid and materially assists ;in

is small because the percentage by weight of the potassium acid fluoride which is used is low in the composition. However, the fluorine thus lib- I erated will attack any silica or siliceous film upon I theiron sulphur particles that may have adhered to the tube, in effect eradicating the film and ex- I posing the iron sulphlde to the action not only of fluorine but mainly to the action of the chlosecuring a proper distribution of the before mena tioned metallic oxides when the mixture of calcium chloride, manganese dioxide and chromic oxide is sprayed upon the coal. Likewise, the matter of maintaining the metallic oxides, above mentioned, in suspension obviates the clogging of pipes and nozzles which may be a part of the apparatus used in spraying the coal.

To some extent, the dextrin functions to rea silica film forms upon these iron sulphide par ticles (the silica coming from silica containin impurities in the coal) which film is not readily attacked by the chlorine. But where potassium acid fluoride has been used in connection with the mixture with Which the coal is treated, this potassium acid fluoride, in the presence of the catalysts, which have'before been mentioned, liberates fluorine. The quantity of fluorine liberated Manganese 'dioxide I Potassium acid, fiuoride rine, which will be decomposed to the stable oxide of iron and sulphur dioxide.

The'present invention is applicable not only in connection with the treatment and burning of .coaLKbut it will be understood that it is also applicable to coke, lignite, peat, and other sub- ;stances of similar categorywherein is involved the same problem of the removal of iron sulphur compounds.

Having thus described my invention, I claim; ..1.'Accomposition of matter for the treatment of coal comprising the following substances by weight: I

Per cent Calcium chloride Approximately 90 Approximately 3 Approximately 3 Approximately" "3 '2. A composition of matter for the treatment Chromic oxide r of coal comprisingthe following substance fby 'Dextrin weight:

I Per cent Calcium chloride i Approximately 90 "Chrom-ic oxide Approximately 3 Manganese -dioxide Approximately '3 "Potassium acid fluoride Approximately 3 Approximately l LAW ENCE P. CRECELIUS.