US2057486A - Process of coking coal - Google Patents

Description

Patented Oct. 13, 1936' -"UNITED STATES PATENT, OFFIQE Humphreys Coal & Coke Company, Greensburg, Pa'., a corporation of Pennsylvania No Drawing."

Application J anuary 22, 1931, Serial'No.510,586

2 Claims. (01. sna -s4.)

My invention relates to new and useful improvements in processes for the coking of coal .inforder to produce coke as used for ordinary fuel, and also foruse in metallurgical operations. The invention particularly contemplates a process which will efficiently and economically produce coke having a comparatively small sulphurcontent, and to this end an object of the invention is to provide a 'method of treating the coal preparatory to being coked sothat sulphur existing in the coal, either free, or in combination, will be eliminated substantially from the coke, or reduced'to so great an extent as not to be objectionable in the use of the cokep A further object is to provide a method of treatment which may be appliedto the sulphurbearing coal previousto the coking thereof and before charging into the oven or other coking apparatus, and thus obviating the disadvantages of treating the coal, or hot, partially coked coal, or the 'finished hot coke, while in. the oven or other coking apparatus."

I will describe my new method as applied 0 to the elimination of sulphur from coal in which at least a portion of the sulphur content exists in the form of a sulphide, for example, pyrite (FeSz), although the coal may contain free sulphur and sulphur in other combinations, such as organic sulphur compounds, sulphates of iron, calcium, copper, and magnesium, and various other forms in which sulphur may occur as compound-ed in coal deposits.

According to the present invention, a sulphur eliminating agent capable of reacting with the sulphur compounds in the coal to form gaseous sulphur compounds which can be eliminated, is mixed with finely divided coal to be coked and previous to charging in the coking apparatus, so that when the treated coal is charged into the coking apparatus the heat incident to the coking operation will accelerate the reaction between said agent and the sulphur compounds to thereby form gaseous sulphur compounds which will pass off or be driven off with other fumes generated during the coking operation. For the purpose stated, I prefer to employ a fluid agent, preferably hydrochloric acid, which will react with the sulphur content of the pyrite to form ferrous chloride and hydrogen sulphide (I-IzS), the latter being gaseous and passing off with other fumes attending the coking operation. The hydrochloric acid of proper strength as hereinafter described, may be applied to the finely divided coal by any suitable i'means which will thoroughly disseminate the acid throughout the coal mass, this step being performed previous to the introduction of the coal into the coking apparatus, as by so doing thorough mixture of the agent with the coal 1' will be accomplished. I prefer to apply the, acid of proper strength to the coal, by causing the finely divided coal to drop or gravitate in a more or less separated or disseminated condition or stream through a suitable chute or duct and spraying the agent by means of an'atomizing steam jet into the coal while, falling. By the procedure just described, the hot acid vapor. is

caused to bebrought into thorough contact with substantially all the coal particles and be disseminated throughout the coalmass, and thus insure complete and efficient, reaction between the acid. and the sulphur compounds in thecoal.

It will be understoodthat'theproportion of acid by weight. to theamount of coal treatedwill depend upon the amount'of sulphur compounds .present in the 'coal. {1 have found by actual operation that. one pound of commercial -Baumy hydrochloric acid (HCl) will serve to remove an approximately .05% content of sulphur from one ton of coal of the character usually employed for the production of coke, and on this basis the quantity of acid necessary to remove a given amount or percentage of sulphur from a ton of coal can be determined readily, it being premised that the sulphur content of the particular coal to be coked is determinable readily by well known methods of analysis. In practice, in treatment of coal of a given pyritic sulphur contentsay, about .15%-about three (3) pounds of commercial 20 Baum hydrochloric acid may be used to one (1) ton of coal in order to reduce the sulphur content in combination, such as pyrite, to the desired extent. It will be noted that the acid is in a highly concentrated form, and it will be understood that the steam employed for the atomizing effect is preferably in such quantity as to reduce the acid concentration as little as possible, as the reaction takes place more effectually with concentrated or strong acid than with more dilute acid; at the same time the steam should be of sufficient pressure to carry the acid into the stream or column of descending coal.

After treatment as above described, the coal may, if desired, be stored in bins or other receptacles until it is desired to coke the same, or may be charged directly into the coking apparatus. It is sometimes advantageous to retain the treated coal for a period previous to coking, as by so doing thorough saturation of the acid with the coal mass is enhanced, and the desired reaction between the acid and the pyrite is initiated and partially accomplished before coking. After treatment, either immediately after the application of the desulphurizing agent, or after the coal treated therewith has been permitted to stand for a desired period, the coal is charged into a suitable coking apparatus-for example, any of the Well known forms of beehive ovenswherein the coking is accomplished by heat in the usual manner. When the treated coal is subjected to the heat of the coking oven, the pyrites are broken down by the heat to iron sulphide (Feisa) and free sulphur, the latter combining with the hydrogen gas generated by the coking to form hydrogen sulphide which passes off with the coking fumes. The iron sulphide (FezSs) resulting as above described, combines with the hydrochloric acid gas to form iron chloride (FeClz) and hydrogen sulphide (H28) which is liberated and passes off with the fumes. It will be understood that the reaction begins when the hot acid vapor is added to the finely divided coal and is continued and accelerated by the heat generated during the coking of the coal. The treatment does not require the use of any critical temperature attending the application of the acid, but it will be found that the colder the coal and the hotter the acid vapor stream when applied, the more promptly the reaction will be initiated.

When referring herein to the coal as being finely divided, I merely mean that the coal is in the divided condition commonly used in well known coking operations.

Among the advantages of the method of procedure above described, are the following:

The preliminary treatment of the coal previous to being charged into the oven assures that the acid can be thoroughly disseminated throughout the mass, and therefore result in a more complete reaction with the sulphur compounds than the case would be if the acid were applied to the coal while the latter were in a more or less compact and dense mass in the oven. The light acid gas formed by the atomization displaces the cold and heavy coal gases and air in the voids of the coal and assures prompt starting of the reaction before the application of heat in the coking oven. The preliminary treatment of the coal also facilitates the handling and application of the acid without extensive or complicated apparatus. The treatment produces a coke of higher quality than would result from the same coal not so treated, the coke being not only free of a large portion, if not all, of its sulphur content, but is of a finer and denser texture, is harder, and of greater weight per given volume or bulk.

What I claim and desire to secure by Letters Patent of the United States is:

1. The method of coking coal containing sulphur in solid form capable of reacting with hydrochloric acid comprising, forming a stream of finely divided coal, spraying the stream with hydrochloric acid of approximately 20 Baum, at the rate of approximately one pound of acid for each .05% of sulphur per ton of coal, and then coking the treated coal whereby hydrogen sulphide formed by the reaction of the acid and sulphur will pass 01f with the fumes resulting from the coking operation.

2. The method of coking coal containing a solid sulphur compound, which comprises producing a stream of raW, finely divided coal with the particles separated, spraying the particles with hydrochloric acid disseminated throughout the stream to cause immediate reaction with the solid sulphur compound to form a gaseous sulphur compound, and thereafter coking the coal in loose, finely divided form with its acid reagent so that the gaseous sulphur compound of reaction will pass off with the fumes resulting from the coking operation, said hydrochloric acid being of high concentration and applied at the rate of approximately one pound for each .05% of sulphur per ton of coal.

ORMAL A. HIGGINS.