US1963861A - Process of and apparatus for separating coal from coal culm - Google Patents

Description

R. N. NOLL June 19, 1934.

PROCESS OF AND APPARATUS FOR SEPARATING COAL FROM COAL CULM Filed 001;. 27, 1931 2 Sheets-Sheet l gnuenfoz dam R. N. NOLL June 19, 1934.

PROCESS OF AND APPARATUS FOR SEPARATING COAL FROM COAL CULM Filed Oct. 27, 1931 2 Sheets-Sheet 2 Jnwnfot R-IV- IVoZZ damn,

Patented June 19, 1934 UNITED STATES PATENT OFFICE mocnss or AND APPARATUS FOR SEPA- RATING coAr. mom com, com

Rosa Nelson Noll, Philadelphia, Pa., assignor of one-fourth to Michael Angelo Sciullo, Vineland, N. J.

Application October 27, 1931, Serial No. 571,391

3 Claims. (01. 209-173) coal and slate into a tank of liquid, the coal floating upon the surface of the liquid and being carried off from the stone or slate which sinks to the bottom of the liquid.

The general object of the invention is to provide a new method of separation which includes the discharge'of the coal from the culm heap into a. flotation medium consisting of a mixture of sulphuric acid and magnesium sulphate, to thereby 'secure a medium of higher density than of sulphuric acid alone and further securing a reduction in the acidity of the resulting solution by virtue of the common ion effect.

A further advantage of the use of this medium resides in the fact that such increase in density brings about a cleaner separation of the culm by reason of the fact that the intermediate densities will all rise to the surface and not be merely suspended within the liquid or distributed therethrough.

A further object is to provide an apparatus whereby this process may be carried out which provides for the use of soft rubber rolls whereby the excess water may be squeezed from the raw culm to thus permit the culm to be used without regard to the water content thereof and to discharge this damped or dry culm to the separating tank, the separating tank containing a medium consisting of a solution of sulphuric acid, together with magnesium sulphate, the worthless impurities being allowed to sink while the floating coal is carried to a discharge chute.

A further object is to provide means whereby the cleaned coal from the separating tank is passed through rollers to thus free the coal of excess medium and the salvaging of this medium so squeezed out of this coal.

Other objects will appear in the course of the following description.

My invention is illustrated .in the accompanying drawings, wherein:

Figure 1 is a vertical section through the apparatus;

Figure 2 is a top plan view thereof;

Figure 3 is a vertical sectional view through the elevating worm for discharging the impurities from the settling tank.

Referring to these drawings, 10 designates the settling tank which is preferably hopper-shaped and may be lined with hard rubber, pitch or like material designated 11. The upper end of the settling tank is open and disposed above this upper end is an endless chain or equivalent element designated 12 having the paddles 13. This endless conveyor passes over the rollers 14 mounted at opposite ends of the tank and driven by any suitable means not shown.

The lower flight of this endless belt or like member is slack and moves through the liquid within the settling tank. The purpose of this endless element 12 is to cause the floating coal to travel from one end portion of the tank where it enters to the discharge end of the tank.

The coal from the culm pile is discharged upon the chute 15 which in turn discharges the coal upon an endless belt or conveyor 16 of any suitable length and of any suitable material. This passes around the rollers 17 and 18 driven in any suitable manner. Above the roller 1'7 there is disposed the roller 19 in relatively close contiguity to the belt. These rollers 17 and 19 are preferably made of soft rubber. This causes the culm to be squeezed and frees it from any excess moisture. The coal after it passes between the rollers 1'7 and 19 is discharged on to a downwardly directed chute 20 which also acts as a scraper operating against the belt 16 and this chute 20 discharges the dry or partially dry coal into the separating or flotation tank 10. Thistank is filled with a solution of sulphuric acid to which magnesium sulphate has been added for the reason which will be hereafter stated.

In the separating tank, the coal floats while the worthless impurities sink to the bottom of the tank. The floating coal is carried by the paddles 13 to the chute 21 and is discharged to the endless belt 22 passing over the rollers 23 and 24 and driven in any suitable manner. Immediately above the roller 24 is disposed a roller 25. One or both of these rollers are of hard rubber and here again the moisture or excess medium is squeezed out of this fine coal, thus freeing the coal from the excess medium, that is, from the sulphuric acid.

The coal passes to the chute 26 where it is sprayed with water by means of a spray pipe 27 which cleans the coal of any medium which. might still adhere to it and likewise forces the coal down the chute into a coal car or any othersuitable receptacle. The medium which has been squeezed out of this coal is caught in a hopper 28 disposed beneath the chute 21 and the endless belt 22 and the rollers 24 and'from this hopper, the acid medium is carried by the pipe 29 to a reserve tank 30. The pipe 29 is .preferably cast iron and the reserve tank is preferably made of spiral conveyor v34 operating within the casing 35. This tubular casing extends upward to any desired height and at its upper end is formed with a discharge opening 36 discharging on to a chute 37. The chute 37 discharges on to an endless belt 38 supported by the rollers 39 and 40 and above the roller 40 there is disposed a roller 41. The rollers 40 and 41 are preferably made of hard rubber or like material and they act to squeeze the liquid medium out of the fine stone or slate. This worthless residue after passing between the rollers 40 and 41 is discharged on to the discharge chute 42, the upper end of this discharge chute 43 acting to scrape the surface of the belt 38 and thus remove all residue therefrom. The same function is performed by the upwardly extending end of the chute 26 previously referred to. Immediately below the endless belt 38 is disposed the hopper 44 which discharges into a pipe 45 in turn discharging the squeezed out acid or medium into the reserve tank 30 from which as before stated it is pumped upward into the main tank.

It will be understood that the contents of the reserve tank are emptied from time to time by means of the pump 32 which is preferably made of manganese steel. The pump 32 does not act continuously. The screw 34 with its housing 35 is also made of cast iron or manganese steel.

The reason for using a medium consisting of a solution of sulphuric acid, together with magnesium sulphate is as follows:Inasmuch as the density of coal ranges from 1.38 to 1.40 while the density of slate ranges from 1.8 to 1.9, it is obvious that the former could be separated from the latter .by selecting a medium such that its density would range between these two densities. The medium used is sulphuric acid but pure sulphuric acid in commercial work is 1.8400. This is rather too high in density to use in this process. The correct condensation, however, may be found by considering it as a problem in direct proportion. The equation will read:The desired density: 1.8400 as a unit volume: X where X is the volume that the strong acid has to be diluted to in order to obtain the desired density. By a series of experiments, the most efficient density was found to be 1.7000. In this medium, the culm is poured in and mixed. The coal immediately rises to the surface of the medium and may be collected in any suitable manner.

It is desirable, however, to raise the density of the sulphuric acid and to this end, a suitable salt such as magnesium sulphate is added to the acid. This causes the density of the sulphuric acid to rise when the salt is dissolved. By raising the density of the sulphuric acid by the use of magnesium sulphate, a safer medium is secured in that the acidity of the resulting solution is decreased and second, because of the rise in density, a cleaner separation of the culm is brought about by reason of the fact that particles of intermediate densities will all rise to the surface and not be merely distributed throughout or suspended in the liquid.

By a series of experiments, it was found that the desired density lies between 1.50 and 1.70

depending upon the type of culm being separated-and the desired volume maybe foundby using the equation heretofore stated. In order to secure the desired density, it is necessary that the acid be diluted with pure water and since the water so used has the magnesium sulphate dissolved therein, the dilutent itself has a density. Therefore, in order to obtain the final volume, take the density of the aqueous solution: 1 (density of water) X V, where V is the volume that the acid-has to bediluted to in order to obtain the desired gravity using water containing magnesium sulphate as the dilutent. By

saving-the medium, the process can be put on a very economical basis. In actual practice, almost 50% of the medium is saved which would otherwise be lost.

By mixing a small amount of magnesium sulphate in a volume of sulphuric acid, the density of the acid will be raised in proportion to the amount of added salt. Now thishas a. decided advantage over the use of the acid alone, since the medium can be made to have a very high density, thus effecting a much cleaner separation. Secondly, when any salt, as for instance, sulphate of magnesium is mixed with sulphuric acid, the resulting solution is far less corrosive than the pure acid. Thus there is produced an excellent medium and at the same time the danger of using it is decreased.

Furthermore, it is a well-known fact that ma nesium and zinc salts have the ability to resist dust when deposited on materials. Thus when culm is separated, the individual coal particles will have a certain dust resisting power. Furthermore, the addition of salt to the acid will mean a less amount of acid to be used and thus there is a distinct saving of the amount of acid needed in the process. Magnesium or zinc salts are suificiently cheap to warrant such procedure. 1 While I have before referred to and prefer to use magnesium sulphate; other salts may be used such, for instance, as sulphate ofzinc, sulphates 'of sodium, potassium or copper.

. While I have described and illustrated what I regard as a very effective mechanism for carrying out my process, I do not wish to be limited to the exact details shown, as obviously these might be modified in many ways without departing from the spirit of the invention, as defined in the appended claims. Thus the rolls 17 and 19, 24 and 25 and 40 and 41 may be of any suitable material which will force the water or acidified water from the culm or from the cleaned coal or refuse. By the use of soft rubber, the no water will be effectively squeezed out of the coal or culm.

I claim:

1. In a process for separating coal in culm from the worthless residue of the culm, the step 135 of discharging the culm into a body of sulphuric acid diluted with a solution of metallic sulphate.

2. A process for separating the coal in culm from the worthless residue consisting in pressing out the water in the culm, discharging the culm into a body of liquid having a density lying between 1.50 and 1.70, removing the floating coal from the surface of the liquid, submitting the coal so removed to pressure to discharge the liquid therefrom, removing the residue from the 1 liquid, and pressing this residue to discharge liquid therefrom.

3. An apparatus for separating coal in culm from worthless residue comprising a tank for containing a suspension liquid, the tank having the form of a hopper, a conveyor discharging the culm into the top of the tank and having in its length liquid expressing rollers of soft rubber between which the culm passes, means disposed above the top of the tank for causing the coal suspended in the upper portion of the liquid to pass from the inlet end of the tank to the discharge end thereof, a second conveyor on to which the coal is discharged, liquid expressing rollers of soft rubber mounted in connection with the second named conveyor and between which the coal passes, a collecting tank, means for carrying the liquid expressed from the coal to said collecting tank, means in the lower portion of the hopper for conveying the worthless residue from the lower portion of the liquid out of the tank, means for expressing liquid from this worthless residue and discharging the residue comprising a pair of coacting soft rubber rollers, means for carrying said liquid to said collecting tank, and means whereby the liquid from'the collecting tank may be discharged back into the main tank.

ROSS NELSON NOLL.

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