US2162200A - Process of preparing dispersions of coal and oil - Google Patents

Description

June 13, M39. s. KIESSKALT tr AL A 2,162,200

PROCESS OF PREPARING DISPERSIONS OF COAL AND OIL Filed May 18, 1956 Patented June 13, 1939 amazon PROCESS OF me DISPEBSIONS or AND 01L Siegfried Kiesskalt, Hans Tampke,

nacker, and Ernst Weingaertner,

Karl Win- Frankforton-the-Main, Germany, assignors to I. G. Farbenindustrie Aktiengesellschatt, Frankforton-the-Main, Germany Application May 1a, 1936, Serial No. 80,440

In Germany 13 Claims.

The present invention relates to a process of preparing dispersions of-coal and oil.

We have found that flowing coal poor in ash and in some cases even free from ash can be a made in one operation in the following manner:

Coal is ground in water in any desired grinding apparatus, for instance in a tube mill oran oscillating device, and in the form of a thick viscous paste is kneaded with oil in a kneading l0. apparatus so as to form a coherent, plastic mass. During this kneading operation the water contained in the paste of coal first separates almost completely and may be drawn ofi. Simultane ously a considerable portion of the ash'is removed together with the water. By a subsequent washing operation during the kneading this ash {removal can be enhanced. By adding the oil by degrees (in 2 to 3 portions) and simultaneously washing with water, it is possible to diminish the g0 ash content of the paste of coal to about 0.5 per cent. During the entire operation the plastic condition of the dispersion of coal and oil is maintained.

During the grinding with water the hydrophile 5 gangue is thoroughly broken up and wetted.

During the kneading of the very viscous paste an intensive mixing of the water phase and the oil phase is produced by the shearing force of the kneading movement, and the ash' together L 80 with the water is eliminated from the dispersion of coal andoil.

By the name "Trent process there is known a process according to which coal groundin water-is made into a paste with oil and an excess as of water and then further treated with a relatively small quantity of oil in a flotation device. During thistreatment the coal particles 'wetted with oil float upwards and are then drawn of! in the form of a non-coherent mass. This process 40 has the drawback that it requires disproportiom ately large quantities of water and, in consequence', large dressing devices. In contradistinction thereto the present process has the advantage that it is possible to obtain a complete re- 45 moval of ash with a considerably smaller addition of water by the kneading with water together with oil. I

The separation may be hastened and the extent of the ash removal and the desiccation may 50 be increased-by adding, according to the character of the coal and the oil, a small proportion of an acid or a base. For instance, the ash removal 'from, and desiccation of, lignite, with the use of lignite tar oils, may be favored by the addition 55 of acids as, for instance, hydrochloric acid, su1- water content does not exceed 35 per cent. It

May 24, 1935 furic acid, acetic acid, oleic acid and phenols. It

may be understood, however, that lignite may' be treated also with other oils by adding acids. On the other hand the ash removal from and desiccation of, coal by means of coal tar oil is .5 considerably acceleratedby the presence of a small quantity of a base, for instance, caustic soda solution, caustic potash solution and aniline. The acid or base maybe added to the aqueous paste before or during the kneading or to the oil.- v

We have furthermore found that some kinds of lignite can yield a dispersion of coal and oil which flows well and can be conveyed with the usual pump devices byusing a paste'of coal and water which has been made with a coal having'a content of water or not more-than about 35 per cent.

In this case it is immaterial whether there is used a coal in the wet state in which it comes from the mine and already containing in this state not more, than about 35 per cent. of water, or a coal which has previously been dried until its f is surprising that the flowing power of a paste prepared with the aid of a coal of this kind is maintained even in cases in which the walls [subsequently made by addition of water into a ;paste of a suitable and increased content of water in order to obtaima mass capable of bein kneaded. I

It may be particularly advantageous to use roller mills as kneading apparatus for carrying out this process. Whereas, in general, in the treatment in roller mills pigments or fllli smaterials are rolled into viscous, plastic masses, for instancedyestuilsinto linseed oil varnish or soot '5 into caoutchouc, it has been observed that in some cases also separating effects can be obtained in roller mills, this being surprising. In a system consisting of coal containing ash, oil and water obtained by an intensive mixing, water 40 and ash may, for instance, be separated by treating the mixture in a roller mill. During this treatment it is noted that when the mixture enters the pass between the rollers, by the action of the shearing force 01 the intake movement, first the water is squeezed outwards from the mixture and then the ash constituents are elimihated with the water.

The drawing diagrammatically shows a device with a roller mill, which device is suitable for the inlet 3 oil is added thereto. The mixture is. as

conveyed by the transporting worm to the rollers t and 5 which are very closely adjusted. In the centre above the two rollers a sump 6 is formed wherein the mixture of coal, oil and water is 5 treated. By the rotation of the rollers the paste is moved in the direction indicated by arrows.

A small quantity of the paste is continuously pressed from the sump 6 between the rollers and forms at the under ports ofthe rollers a thin 10 fllm I and 8 the weight of which is about 1 of the mass in the sump 8. During the going through between the rollers the main quantity of the water contained in the paste is removed and drops to the bottom 9. The fllms I and 8 are loosened from the rollers by scrapers II and H and fall over slide plates l2 and it into suitable containers.

The advantage of using roller mills for this process is that on the one .hand the .operation may be continuous with a considerably lower consumption of power than, for instance, in a. Werner-Pfleiderer kneading apparatus. On the other hand, by the action of the shearing force on the highly viscous paste the particles of coal 2 are more finely crushed so that further particles of ash are dissociated from the coal and eliminated. It, follows that an additional quantity of ash may thus be separated from the paste from which with the aidot kneading and-watering so in the Werner-Pfleiderer kneading apparatus ash can no longer be separated. The kneading process which according to the properties of the coal lasts only a few minutes may be considerably accelerated by an addition which increases the tendency for the coal to be wetted by oil and reduces the tendency for it to be wetted by water, such as tetrahydronaphthalene, benzene,-aniline and alcohols of high molecular weight. The separation of water '40 caused by the kneading process may be improved by the application of a temperature of about40 C. to- 100 0., and if required, by the application of a reduced pressure. The grinding operation in the aqueous phase as preceding the kneading operation affords an opportunity for a simultaneous chemical treatment, such as desulfurization, removal of iron and the like.

The process may be applied for the manufacture of flowing coal, and also for the manufacture of dust coal poor in ash in which case the oil, suitably of low boiling point,- present in the paste is evaporated. By this method it is also possible to make dispersions of graphite in lubricating oils, such as are used for lubricating movable engine parts. For this purpose there are suitable not only graphite but also anthracite, coal. lignite, coke and semi-coke, but particular- I! wastecoal rich in ash as obtained in the go washeries oi the coal dressings.

In comparison with the hitherto usual method for the manufacture of flowing coal, the process has, apart from the quality of the products obtained, the advantage that-it is posibie to apply 55 the wet grinding process for the manufacture of flowing coal free from or poor in ash, whereby there isattained, in comparison with the dry grinding process, a considerable savingof energy with an improved output of fineness.

In comparison with the known flotation process the process of thepresent'invention is distinguished by the fact that in the plasticv phases there is required only a fraction of the water which must be used in these known processes.

The following examples serve to illustrate the equal weight of water.

amaaoo water and most of the ash separate. A dispersion of coal and oil is produced containing only 1 per cent. of ash.

(2) A coal having an ash content of 8.3 per cent. is treated as described in Example 1. The dispersion of coal and oil of 50 per cent. strength which is produced shows an ash content of only 1 per cent.

(3) parts of a lignite coke containing 19.2 per cent. of ash is finely ground with 100 parts of water for about 15 hours in an oscillating device such as that described in U. S. patent ap-. piication Serial No. 731,172, flied June 18, 1934, in the name of Siegfried Kiesskalt and Walther Meier. The aqueous paste so obtained is then kneaded in a WerHer-Pfleiderer kneading apparatus with 100 parts of a mineral oil. Together with the separation of the water most of the ash separates and is eliminated by elutriation with water. There is obtained a dispersion of coke and oil containing 4.1 per cent. of ash.

(4) 100 parts of a dry coal having an ash content of 14.4 per cent. and 50 parts of water are made into a paste in a known kneading apparatus. After the addition of 100 parts of crude oil, 40 parts of water together with most of the ash separate within a few minutes. The separa-- tion of ash is completed by subsequently rinsing with about to 200 parts of water, while con tinuously kneading. About 210 parts of a paste of coal and oilare producedcontaining only 1 per cent. of ash and 5 per cent. of water.

(5) A lignite containing 12.8 per cent. of ash and in the wet state in which it comes from the mine is ground in a suitable grinding device. In a known kneading machine, for instance in a Werner-Pfleiderer kneading apparatus, the ground coal is flrst mixed with water and made into a paste and subsequently kneaded with an equal weight of a lignite tar oil, calculated upon the dry coal, while adding 1 per cent. of sulfuric acid. After some minutes the water and most of the ash separate. There is produced a dispersion of coal and oil containing only 1 per cent. of ash.

(6) A coal containing 7.3 per cent. of ash is flnely ground in an oscillating device with an In a Werner-Pfleiderer kneading machine the coal is kneaded in the form of an aqueous paste with an equalweight of coal tar oil, calculated 'upon the dry coal, while adding 0.5 per cent. of caustic soda solution of 40 B. After some minutes the water and most of the ash separate. The dispersion of coal and oil of 50 per cent. strength produced has an ash content of 0.9 per cent.

(7) A coal containing 11.8 per cent. of ash is flnely ground with an equal quantity of water in a suitafle grinding apparatus. The coal is kneaded in a Werner-Pfleiderer kneading apparatus in the form of an aqueous paste with two thirds. of its weight (calculated upon the dry coal) of coal tar oil, with the addition .of 0.2 per cent. of caustic soda solution of 100 per cent. strength. After a short time most of the water together with the ash can be .separated. The dispersion of coal and oil, thus already freed from ash to a large extent, is then further kneaded in a Werner-Pfleiderer kneading apparatus in the presence of water and together with 2 per cent.

of sulfuric acid calculated upon the weight of (8-) 100 parts of aground lignite in the wet state in which it comes from the mine and cona large part of ash are separated.

taining 55 per cent. of .water and 12.7 per cent. of ash, calculated upon anhydrous lignite, are kneaded together with 18 parts of water so as to form a paste. On addition of 2 per cent. of sulfuric acid, calculated upon the dry lignite, and 45 parts of lignite tar oil, about 45 parts of water and 15 parts of water are added to the paste of lig nite and oil and kneading is continued. By kneading with this small quantity of water .the residual ash is separated from the paste or lignite and oil and may be removed with the water. This procedure is repeated four times more, using 15 parts of water each time. After the five treatments, the removal of ash hasproceededto such an extent that on further kneading the paste with water the supernatant rinsing water remains clear. The paste of lignite and oil which is produced has an ash content of only 1 per cent. and a water content of about 20 per cent. that is to say, the water content of the lignite in the ,wet state as it comes from the mine has been reduced by about 50 per cent.

'(9) 156 parts of a lignite in the. wet state in which it comes from the mine and containing 55 dry lignite, are made into'a paste in a suitable kneading apparatus together with 44 parts of water and 5.3 parts of hydrochloric acid of 100 per cent. strength, and the paste is kneaded with about 63 parts of a lignite tar. After a short time about '70 parts of water separate, together with most-of the ash. By kneading in the presence of further 100 to 150 parts of water the separation of ash is finished. The dispersion of lignite and oil which is produced contains about 1 per cent. of ash and can be readily formed into briquettes in the known briquetting plants.

A coal containing 11.6 per cent. of ash is finely ground in an oscillating device with about an equal weight ofwater. The aqueous paste of coal isomixed in a suitable mixing apparatus with about an equal weight of coal taroil, calculated upon dry coal, while adding 0.5 per cent. of caustic soda solution of 40 B.,'likewise calculated upon dry coal. The mixture is then introduced 6 times successively into a tworoller mill during which operation the water and most of the ash separate. The dispersion of coal and oil obtained, of 50 per cent. strength, has an ash content of'only 1 per cent. o

(11) 150 parts of an aqueous coal paste which consists of 60 parts of .water and 90 parts of ground dry coal having an ash content of; 11.5 per cent. are kneaded in a roller mill together with 0.5 per cent. of caustic soda solution, calculated upon the anhydrous coal and '70 parts of a coal tar oil. After the paste has passed through the rollers several times, about 54 parts ofwater and most of the ash separate from the hydrous, spongy mixture of coal and oil. The separation of ash is completed by subsequently rinsing with a small quantity of water. ln order to obtain a dispersion of coal and oil which is easily conveyed further 10 parts of coal tar oil are rolled into the mixture. There is obtained a dispersion of coal and'oil containing 1 per cent. of ash and about-3 per cent. of water. i

(12) 128 parts of an aqueous paste of lignite consisting of 100 parts of ground lignite in the wet state inwhich it.comes from the mine and' having a water content of 55 per cent., 28 parts a paste of coal and oil which has a water content of,8 percent. and an ash-content of about 1 per cent.

(13) 156 parts of a salt-containing crude lignite having a water content, of 50 per cent. and' corresponding to 70 parts of dry lignite are previ-' ously dried by waste heat to produce 120 parts of lignite having a water content of 35 per cent.

"The lignite is then made into a paste in a'suitable kneading devicetogether with 47 parts of water and 5.85 parts of hydrochloric acid of 100 .per cent. strength (7.5 per cent. calculated upon dry lignite) and the paste is kneaded with 44 parts or lignite hydrogenation oil. Aftera short time About 45 parts of water phase reversal occurs. I and most of the ash separate. By kneading in the presence-of further 100 parts of water the separation of ash is completed. The paste of coal. per cent. of water, corresponding to 70 parts of plastic condition to a squeezing and shearing ac-- tion for a suflicient time toreplace the water by the oil and materially reduce the ash content oi! the coal and removing the ash and water which separate.- I s 2. Process of preparing dispersions of coal and oil which comprises-subjecting a paste of coal and water with about an equal quantity of 011 calculated upon the dry coal, while continuously maintaining the plastic condition-to asqueezing and shearing action for asufllcient time to replace the water by the oil and materially reduce the ash content of the coal and removing the ash and water which separate.

' 3. Process 01' preparingv dispersions of coal and oil which comprises'kneading 'a paste of coal and water with oil by means-of a roller mill wherein the oil is added'by degrees while continuously .maintaining the plastic condition for a suflicient time to replace the water by the oil and materially reduce the ash content ofthe coal and removing the ash and water which separate.

4. Process of preparing dispersions of coal and oil which comprises kneading a paste of coal and water with about an equal quantity of oil, calcalated updn the dry. coal, by means 01 a roller mill wherein the oil is added by degrees while continuously maintaining the plastic condition for a 7 6. Process of preparing dispersions of coal and oil which'comprises subjecting a paste of lignite in the wet state in which it comes from the mine and water with oil while continuously maintaining the plastic condition to a squeezing and shearing action for a sufllcienttime to replace the water by the oil and materially reduce the ash content of the coal and removing the ash and water I which separate.

7. Process of preparing dispersions of coal and oil which comprises subjecting a paste of coal and water with oil while continuously maintaining the plastic condition to a squeezing and shearing action for a suflicient time to replace the water by the oil and materially reduce the ash content of the coal, washing the dispersion with water during the kneading process and removing the ash and. water which separate.

8. Process of preparing dispersions of coal and oil which comprises kneading a paste of coal and water with about an equal 'quantity of oil, calculated upon the dry coal, by means of a roller mill wherein the oil is added by degrees while continuously maintaining the plastic condition for a suflicient time to replace the water by the oil and materially reduce the ash content of the coal washing the dispersion with water during the kneading process and removing the ash and water which separate.

9. Process of preparing dispersions of coal and oil which comprises subjecting a paste of coal and water containing a small quantity of an acid with oil while continuously maintaining the plastic condition to asqueezing and shearingaction for a suflicient time to replace the water by the oil and materially reduce the ash content or the coal and removing the ash and water which separate.

10. Process of preparing dispersions of coal and oil which comprises kneading a paste of coal and water, containing a small quantity of an acid, with oil by means of a roller mill wherein the oil is added by degrees while continuously maintaining the plastic condition for a sumcient time to replace the water by the oil and materially reduce the ash content of the coal and removing the ash and water which separate. I

11. Process of preparing dispersions of coal and oil which comprises subjecting a paste of coal and water, containing a small quantity of a base, with coal tar oil while continuously maintaining the plastic condition to a squeezing and shearing action for a suflicient time to replace the water by the oil and materially reduce the ash content of the coal and removing the ash and water which separate. I

12. Process of preparing dispersions of coal and oil which comprises kneading a paste of coal and water, containing a small quantity of a base, with coal tar oil by means of a roller mill wherein the oil is added by degrees while continuously maintaining the plastic condition for a sufllcient time to replace the water by the oil and materially reduce the ash content of the coal and removing the ash and water which separate.

13. Process of preparing dispersions of 'lig'nite and oil which comprises kneading by means of a roller mill a paste of lignite and water with about an equal quantity of oil, calculated upon the dry lignite, said paste containing a small quantity of hydrochloric acid while continuously maintaining the plastic condition for a sufllcient time to re place the water by the oil and materially reduce the ash content of the coal, washing the dispersion with water during the kneading process and removing the ash and water which separate.

SIEGFRIED KIESSKALT. HANS TAMPKE.

KARL WINNACKER. ERNST WERNGAER'I'NER.

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