US1678387A - Briquette and process for producing it - Google Patents

Description

No Drawing.

Patented July 24, 1928.

PATENT OFFICE.

ROBERT MARION HALE, OF NEW YORK, N.

NORTH AMERICAN CORPORATION, OF

MARYLAND.

'Y., ASSIGNOR TO MINERALS SEPARATION BRIQUETTE AND PROCESS FOR PRODUCING IT.

Application filed April 30,

This invention relates to briquettes and to processes for producing them, and is herein illustrated as applied to the manufacture of coal briquettes which include both oily material and sulphite cellulose residues as binding materials.

It had hitherto been supposed to be impossible to commercially make weather-proof briquettes in which sulphite cellulose residues alone served as a binder. Briquettes containing sulphite cellulose residues as a binder usually disintegrated when wet. In the endeavor to avoid the disintegration in water which occurs with briquettes bound by sulphite cellulose residues alone, fuel oil and other substances have been emulsified or partially emulsified with the sulphite cellulose residue with the object of producinga weatherproof briquette, but the results have been unsatisfactory. -Moreover, it has hitherto been found diflieultto uniformly bake briquettes containing sulphite cellulose residues, either alone or with other substances. The sulphite cellulose residues vary in composition, and it has heretofore been found that the baking which was proper for one lot was usually incorrect for the next lot. Moreover. thelarge amounts of sulphite cellulose residues which it has been deemed necessary to use in briquetting some coals have increased the cost of the briquettes to prohibitive figures. As much as 18 per cent of sulphite cellulose residues has been found necesiary.

Besides this the briquettes heretofore producedon a commercial scale have been unsatisfactory. The briquettes yielded a large amount of dust in breaking, thus increasing the waste. The briquettes disintegrated in the fire and so a large proportion fell through the grate bars unburned. The disintegration of the briquettes in the fire, wmcn permits large quantities of unburned carbon to pass into the ash and allows the fine ash to accumulate sons to choke the draft. is due in part to the difficulty of uniformly distributing the binder over dry unoiled coal. The fact that some particles have too much binder while other particles have too little or none at all causes the briquette to crumble as soon as the outer shell is destroyed. Moreover, it has been the usual practice to avoid using fines as much as porsiblc in briquetting, except only in 1926. Serial No. 105,627.

' was necessary in order to keep at a minimum the area of the surfaces of the particles of coal and thus to reduce the amount of binder necessary to coat these surfaces. Briquettes made from coarse coal are not as uniform in appearance as those made from fine coal. They break more easily than those made from fine coal,

According to the pre:ent invention these and other difliculties have been overcome. Briquettes have been produced'in which a large proportion of the binder consisted of sulphite cellulose residues, and the briquettes were weather-proof, easily produced by commereially standardized methods of mixing, treating and baking the constituent materials. and which burned out almost completely in the fire, substantially retaining their shape without shrinkage in an ordinary domestic fire until the carbon was almost completely burned out, so that the ash skeleton of the briquette after cooling could be removed intact. Ob:ervation indicated that not more than two or three per cent of unburned carbon remained in the ashes. Moreover, so far as observed the briquettes did not form clinkers, but the ash skeletons of the briquettes were easily crushed topowder in the fingers. Such briquettes immersed in water for twenty hours absorbed from less than two per cent of water to (occasionally) about seven per cent of water. The. briquettes when white hot andtaken from the fire retained 'their shape and were so hard that quite a hard blow was neceswould not break in falling three or four feet upon a concrete or iron floor. Moreover. when broken they broke into pieces of considerable size and did not crumble into dust a; most briquettes do.

To obtain these results it was found that the coal used should be crushed fine and should be oil-coated or coated with some oily material. Fine crushing is advantageous since/it enables high-ash coal to be u::ed, in which the ash can be mechanically freed from the carbon by the crushing and then se rated l" concentrating processes.

'lhefconcentrating process best adapted for this work is the froth-flotation process which ordinaril leaves the coal oil-coated, and avoids the need of drying to the extent hitherto used. The coating thus obtained is binder flocculation is easily accomplished on some coals in connection with frotli-flot-ation concentration.

Where much ash or gangue is present in the impure coal most of the oil needed for agglomeration is i)referably added after most of the ash and gangue has been separated from the purified coal, thus minimizing loss of oil by entanglement 'in the ash gangue. By proper treatment it is possible to float the agglomerates on air bubbles and overflow them, thus separating out the major portion of the pulp water in which they were floated. Agglomerates containing sufficient oil or oily material to. serve as a binder are described in Patent No. 1,512,199, October 21, 1924, to Stenning, Williams, Beasley and Middleton.

According to the present invention, agglomerates or other oil-coated concentrates containing insufficient binder to be moldable into strong briquettes are dewatered to contain, preferably, less then ten per cent of moisture, and then are mixed with further binding material consisting partly or wholly of sulphite cellulose residues.

The resulting mixture is then shaped into briquettes under pressure and baked. The briquettes thus produced may be dropped upon stone from a height of several feet without breaking. Instead they rebound as if elastic. If broken they yield little dust.

, They are, therefore, well adapted to be handled by the machinery usually employed for the automatic handling. of coal.

Other features and advantages will appear in connection with the following examples:

Emample' 1.Domestic anthracite ashes dumped at Corona, Long Island, N. Y., were ground to pass a 35 mesh Tyler standard screen and concentrated in an aqueous pulp by the froth-flotation process. The pulp Wasfed to a froth-flotation minerals separation machine having eight cells, the first six being subaeration cells and the seventh and eighth standard cells. The pulp entered the first cell and the tailings were discharged from the.sixth cell. The concentrates from the first cell went direct to a thickener. The concentrates from the second, third, fourth, fifth and sixth cells went to the seventh cell. The reject from the eighth cell was a middling which went back to the first cell. The concentrates from the seventh and eighth cells went to the thickener. The concentrates from the thickener Went to an Oliver filter. The feed contained 56% ash, the filter cake 11.5% ash and the refuse 83.75% ash. This gave one ton of coal from 2.6 tons of ashes fed to machine. Mexican fuel oil was added at the ball grinding mill and the first cell in the form of a soap solution together with a soluble mineral-frothing agent. The oils were added at the rate of 0.76% of contained oil computed on the feed, or 1.98% computed on the filter cake.

The moisture in the filter cake was further reduced by drying and drainage to about 7%, and then the concentrates were mixed in a C. P. Day dough mixer with 5% of their weight of Mexican fuel oil and 3% of their weight of sulphite cellulose residues from Robeson Process Company. It was found preferable, in orderto ensure evenness of mixture, to mix the thick Mexican fuel oil and the thinner sulphite cellulose residues together to form something resem bling an emulsion, and then add this mixture to the mixer. The resulting coal mixture was fed to a set of Mashek (Belgian type) briquetting rolls to form pillow briquettes, nearly two inches square and about one and a half inch thick. The briquettes did not stick to the rolls or disintegrate. They were placed in a baking oven for one and one-half hours, the temperature rising rather slowly to somewhat over 500 F. and finally cooled. The resulting briquettes were hard, smooth, burned smokelessly and left an ash nearly free from unburned carbon. Another batch of excellent pillow-shaped briquettes. was made from similar ash concentrates by adding 5% Mexican fuel and 3% sulphite'cellulose residues. These were baked at a temperature which slowly rose to 550 F. A hot briquette then removed was crushed by a weight of 85 pounds bearing upon its curved surface, but not by a weight of 80 pounds. Upon further baking for an hour and a half at a temperautre between 500 F. and 550 F. the crushing strength hot increased until a weight of 1 25 pounds failed to crush the briquette. The cooled briquettes were much stronger.

Another batch of baked briquettes simihouse oil from a local New York gas works Eimmyflc 2.High ash anthracite sludge from Lehigh Coal and Navigation Company was ground to pass 35 mesh and concentrated by froth-flotation in an aqueous pulp with 0.96% of a mixture containing cresylic acid gas house oil 57%, and gas house tar 23%. The aqueous pulp was fed to an eightcell minerals separation subaeration machine. T he pulp entered the first cell and the tailings were discharged from the sixth cell. The concentrate'from the first cell went to the seventh cell. The concentrates from the second, third, fourth, fifth and sixth cells were returned to the first cell for retreatment. The cleaned concentrates from the seventh and eighth cells went to a thickener and thence to an Oliver filter. The reject from the eighth cell was a middling which went back to the first cell. The flotation feed contained 27.75% ash. the concentrates contained 16.25% ash, the filter cake 15.75% ash, and the refuse 87.5% ash. This gave one ton of clean concentrates from 1.2 tons of feed recovering 97.2% ofthe combustible material in the feed.

In the seventh and eighth cells the concentrates, in addition to being cleaned, were agglomerated by the addition of 3.44% of oils consisting of 1.5% of gas house oil, 39.4% of hydrolene (an artificial asphaltic material) and 59.1% of crude gas house tar, added at the seventh cell. The resultant concentrates were. estimated to contain a little over 4% of oily materials.

The filter cake containing 22.4% moisture was passed through an Anderson oil expeller and the moisture reduced to 15.5%. The Anderson cake was then mixed in a C. P. Day dough mixer with 3% sulphite cellulose res idues. This and baked as in Example 1. The briquettes were baked slightly longer being in the oven for one and one-half hours at 500 F. to

550 F. The resultant briquettes'were hard, smooth and excellent in every way in spite of the large moisture content when made.

They burned like those of Example 1 leaving an almost coal-free intact ash skeleton.

Example 3.-Anthracite sludge from Philadelphia and Reading Coal and Iron Company containing 24.75% ash was ground to pass about mesh and concentrated by froth-flotation in an eight -cell minerals separation subaeration machine. An aqueous emulsion of Mexican fuel oil with a little laundry soap was added at the ball grinding mill so that 21.9 pounds'of the fuel oil and soap were added per ton of raw coal. There was also added at the ball mill 1.07 pounds 'cresylie acid and 5.08 pounds of gas house oil from a Long Island gas works,bot-h per ton of raw coal. There was further added 0.92 pounds of the gas house oil and 0.16 pounds cresylic acid at the first cell, both per ton of raw coal. The pulp entered the aterial'was then briquetted first cell and the tailings were discharged.

tailings contained 83.75% ash. 96% of the' combustible'material in the feed was recovered in the final filter cake. One ton of clean coal was recovered from 1.23 tons of feed.

The resulting concentrate was filtered yielding a filter cake containing 11% ash.

The filter c'ake further drained for four or five days and then contained about 7.5% water.

These fairly dry concentrates were mixed in a C. P. Day dough mixed with a further 5% Mexican fuel oil and 3% of sulphite eCGlllllOFB residues from Robeson Process Company, previously mixed together as described under Example 1. I

The resulting coal mixture was .briquetted as in Example 1, and the briquettes were baked for an hourand a half at a temperature rather above500 F. The resulting briquettes were excellent. They stood handling well and burned easily and substantially completely without dust loss.

Example 4.New River, West Virginia, bituminous coal ground to substantially pass 35 mesh was agitated in an aqueous pulp with Mexican fuel oil to coat it with about 3% of the oil. The oil-coated coal was filtered and mixed with 5% of the sulphite cellulose residues and then formed into briquettes in a hand mold, under suflicient pressure to form a handleable briquette. The resulting briquettes were baked one hour at 450 F. When tested it appeared that the swelling of this coal which normally takes place when heated, had been greatly reduced with consequent improved burningqualities. .lVhen the coal was not pre-coated with oil, it required such a large amount of binder that the cost of the process was commercially prohibitive. v

Having thus described certain embodiments of the invention what is claimed is:

1. A briquette consisting ofcoal finer than 20-mesh bound by a binder which contains a considerable proportion of oil and also a considerable proportion of sulphite cellulose residues and contains substantially no added inorganic substance. y

2, A baked briquette consisting of coal finer than'20mesh.which contains as binder less than ten per cent by weight, said binder together by a binder of which at least onethird is sulphite cellulose residues and which contains substantially no added inorganic substance.

4. A baked briquette which is substantially Weather-proof and will endure being dropped from a. height of several feet either without breaking or breaking so as not to yield any notable amount of dust, and com posed of coal finer than QO-mesh bound together by a binder consisting partly of oil and partly of sulphite cellulose residues.

5. A baked bituminous coal briquette consisting of coal particles finer'than 20-mesh held together by a binder consisting largely of sulphite cellulose residues and capable of withstanding rough handling but containing less than twelve per cent of total binder.

6. A bituminous coal briquetje consisting of coal particles finer than QO-mesh bound partly by oil and partly by sulphite cellulose residues so that there is less than twelve per cent of binder all told, and which has been rendered weather-proof by baking.

7. A weather-proof baked briquette consisting of coal finer than QO-mesh bound by the residue of oily material and sulphite cellulose residues, burning in a domestic fire so that less than ten per cent unburned carbon remains in the ash, and leaving a substantially complete ash skeleton when it burns out.

8. A weather-proof baked briquette consisting of coal finer than .ZO-mesh bound by the residue of oily material and sulphite cellulose residues, capable of being dropped from a height of several feet without breaking and rebounding elastically when so dropped, burning in a domestic fire so that less than ten per cent unburned carbon remains in. the ash, and leaving a substantially complete ash skeleton when it burns out.

9. The process of making coal briquettes which consists in mixing a few per cent of sulphite cellulose residues with oil-coated coal particles and pressing the mixture into briquettes.

10. The process of making coal briquettes which consists in-mixing a few per cent of sulphite cellulose residues with coal particles substantially uniformly coated with a small percentage of a binding oil, and pressing the mixture into briquettes.

11. The process of making coal briquettes from impure coal which consists in agitating an aqueous pulp of the impure coal with a mineral-frothing agent and an oily agent so as to obtain an oil-coated coal, mixing with it sulphite cellulose residues, and forming it into briquettes.

12. The process ofmaking coal briquettes from impure coal which consists in agitating an aqueous pulp of the impure coal with a mineral-frothing agent and an oily agent so as to obtain an oil-coated coal, drying it, mixing it with sulphite cellulose residues, forming it into briquettes, and baking the briquettes. I

18. The process of' making coalbriquettes from impure coal which consistsin agitating an aqueous pulp of the impure coal with a miner'al-frothing agent and an' oily agent so as to obtain an oil-coated coal floated as a concentrate, separating the float, drying it, mixing it with further oil and with 'sulphite cellulose residues, forming it into briquettes, and baking the briquettes.

14c. The process of making a' bituminous coal briquette which consists in mixing oilcoated bituminous coal particles with sulphite cellulose residues, forming the mixed materials into briquettes, and baking the briquettes at a temperature in the neighborhood of 500 F.

'15. The process of making briquettes which consists in coating fine coal with not more than a few percent of oily material, mixing the coated coal with a few ,per cent of sulphite cellulose residues, forming the mixture into briquettes, and baking the briquettes to make them. weather-proof.

16. The process of making briquettes which consists in agitating an aqueous pulp of fine coal with oily material to coat it but insufficient in quantity to bind it, separating the coated coal from the major portion of the water, mixing it with sulphite cellulose residues, forming .the mixture into briquettes, and baking the briquettes to make them weather-proof.

17 The process of making briquettes which consists in agitating an aqueous pulp of fine coal with oily material and a mineral-frothing. agent to produce overflowing coatedcoal separated from most of the pulp water, mixing the coated coal with sulphite cellulose residues, forming the mixture into briquettes, and baking the briquettes to make them weather-proof.

which consists in agitating an aqueous pulp .of fine coal with oily material to'coat it but insuflicient in quantity to bind it, separating the coated coal from the major portion of the water, mixing it with oily binder and-- sulphite cellulose residues, forming the mixture into briquettes, and baking the briquettes to make them weather-proof.

19. The process of making briquettes which consists in agitating an aqueous pulp of fine coal with oily material and a min-v 1 10' 18. The process of making briquettes which consists in agitating an aqueous pulp of fine coal with oily material to coat it but insufiicient in quantity to bind it, separating the coated coal from the major portion of the water, mixing it with a mixture of oily binder and, sulphite cellulose residues, forming the mixture into briquettes, and bakirg the briquettes to make them weatherroo p 21. The process of making briquettes which consists in agitating an aqueous pulp of 'fine coal with oily material and a mineral-frothing agent to produce overflowing coated coal separated from most of the pulp water, mixing the coated coal with a mixture of sulphite cellulose residues, and with oily binder, forming the mixture into briquettes,

and baking the briquettes to make themweather-proof. p

22; The process of making briquettes which consists in grinding ashes to free the contained coal from the ash, concentrating the coal by froth-flotation in the presence of an .oily material, drying the concentrates to less than 15% of water, mixing the dried concentrates with a few per cent of sulphite liquor, molding the concentrates into briquettes, and baking the briquettes at a temperature exceeding 300 F. and not exceeding 500 F.

23. The process of making briquettes which consists in grinding ashes to free the contained coal from the ash, concentrating the concentrates into briquettes, and baking the briquettes at a temperature exceeding 300 F. and not geratly exceeding 500 F.

24. A coal briquette consisting of coal finer than 20-mesh bound by less than twelve per cent of a binder which consists partly of greatly oil and contains a large proportion of cellulose residues.

In testimony whereof, I have afiixed my signature to this specification.

ROBERT MARION HALE.