CS266318B2 - Process for preparing aglomerate from aqueous coal sludges - Google Patents

Description

KEREKES ANDRAS, BUDAPEST, SZABÓ FERENC dr., DunaujvAros vasmU, RÉPASI GELLÉRT dr., KUSLITS TIBOR, GEILING BÉLA, DUNAUJVAROS, KOVÁCS LÁSZLÓ dr., GAL DEZSY KAR dr. ANDRÁS dr., KESZLER AGNES, MÓGER GALINA dr., KROÓ ERIK, BUDAPEST (HU)

MTA KOPPONTI KEMIAI KUTATO INTESEZET, BUDAPEST (HU), DUNAI VASMU, DUNAUJVAROS (HU)

(57) Coal sludge with a dry matter content of 150 to 300 g per liter, where the dry matter contains 30 to 40% by weight of non-combustible substances, is mixed with heating or tar oil containing 1 to 10% by weight of coal pitch. or with crude tar in an amount of 25 g per liter of sludge, preferably together with pulverized coal or finished agglomerate and optionally with 0.01 to 1.0% by weight of surfactant, based on the dry sludge content of the coal sludge. The mixture is mixed with water vapor at a pressure of at least 0.02 MPa and the moisture of the agglomerate is reduced to a maximum of 10% after separation from the tailings. The method allows the mixing of coal sludge and binder and heating of the mixture in a single process.

CS 266 318 B2

The invention relates to a process for producing an agglomerate having good mechanical properties and high flammability from aqueous coal sludge.

Methods are known in which aqueous coal sludge, which heavily contaminates the environment and causes storage problems, is processed into a mold suitable for further processing. Numerous patents disclose the use of coal sludge and in particular its agglomeration.

The first step of each of the known methods is to mix aqueous coal sludge with a binder, which is typically a liquid hydrocarbon. The mixing can be carried out mechanically, for example by a propeller stirrer, ultrasound, or a hydrodynamic method, in which two liquid phases with a large speed difference are brought into contact with each other. As a result of mixing, the coal sludge grains adhere to the oil emulsified in water and form an agglomerate of filterable size. In general, it is preferable that the mixing is carried out at higher temperatures. Some suggestions, such as US Pat. No. 4,234,320 recommend agglomeration in two phases: an aqueous suspension of solids is first mixed with a hydrocarbon binder under intensive stirring, the resulting agglomerate is separated from water and non-agglomerated grains, and then placed in a mixer containing higher temperature water. than the softening temperature of the binder. Additional binder is then added to the mixer and the resulting agglomerate of better quality than the first stage agglomerate is separated from the hot water in the vibration separator, which is returned to the process.

The method of another U.S. Pat. No. 4,126,426 differs from the previous in that, prior to agglomeration, the coal sludge is divided into two fractions according to the grain size. A fraction with a smaller grain size below 0.1 mm is mixed with a binder and agglomerated, then separated and, after dewatering, a fraction with a larger grain size which is easier to process is added thereto. Liquid hydrocarbons are also used as binders. The method is more efficient at higher temperatures.

According to the Belgian Pat. No. 874,315, agglomeration-inducing agitation is carried out in a hydrodynamic manner: The liquid hydrocarbon is mixed with the liquid coal slurry, agglomerated after mixing and separation is carried out in a filter centrifuge. It is advisable to prepare a suitable hydrocarbon emulsion prior to incorporation into the coal sludge.

According to British Pat. U.S. Pat. No. 2,024,250, which provides accurate mixing and viscosity data, prevents flotation prior to agglomeration to concentrate dry matter. A great advantage of this method is the low oil consumption.

According to German Pat. No. 2,753,628, the agglomeration is carried out with an aqueous oil emulsion. After separation, the procedure is repeated with non-agglomerated tailings. High boiling oils are used and the efficiency of the process is increased by the addition of surfactants. Separation of the agglomerate from the tailings and water is carried out on a shirring screen and the agglomerate is then purified from the tailings by washing.

On the basis of said patents, it can be concluded that the main characteristics of the known processes are the following: the aqueous coal sludge is mixed with the liquid hydrocarbon binder so that the particles form a filterable agglomerate. Mechanical, hydrodynamic and ultrasonic processes are used for mixing. The agglomeration proceeds more efficiently at a higher system temperature. The hydrocarbons used are predominantly various petroleum liquid fractions and hydrocarbon distillation products. If desired, the product is further dried mechanically and / or thermally.

In the known processes, mixing coal sludge with agglomerating substances and heating the mixture always involves two separate technological phases, thereby significantly increasing the processing time and increasing the equipment requirements. A disadvantage of the known technology, which uses various liquid hydrocarbons to agglomerate particles, is that the product is not easy to handle and its calorific value is not very good.

The purpose of the invention is to overcome these disadvantages and to produce fuel with a high calorific value and a low ash content in an economical manner in a single technological phase.

CS 266 318 B2

SUMMARY OF THE INVENTION The present invention provides a process for producing agglomerate from aqueous coal sludge having a dry matter content of 150-300 g per liter, wherein the dry matter comprises 30-40% by weight of non-combustible material and wherein the coal particles have a size up to 0.5 mm. , precipitates and precipitates out. SUMMARY OF THE INVENTION The coal sludge is admixed with fuel oil or tar oil containing from 1 to 10%, preferably from 2 to 4%, by weight of the coal oil. Allow knows ^r 2> j пл I poured iiholnóho к л I 11 nnmn at 20-90 ° C, stirred with water vapor at an overpressure of at least 0.02 MPa, and the moisture of the agglomerates after separation from gangue material is reduced to not more than 10%. Preferably, pulverized coal or finished agglomerate in an amount of 50-500 g of the mixture is added to the coal sludge. According to the invention, it is advantageous to add to the mixture 0.01 to 1.0% by weight, based on the dry matter content, of an ionic surfactant consisting of alkali metal salts of sulfonated aliphatic and aromatic compounds or of a nonionic surfactant selected from polyoxyethylene derivatives and plant lecithins. .

the effect of steam is greatly enhanced when air is simultaneously introduced into the mixture. Preferably, the oil is injected into the coal sludge by means of mixing steam. The process according to the invention substantially improves the filterability, mechanical strength and separability of the product from the tailings, reduces the ash content of the product and increases its calorific value, and improves the mechanical properties of the agglomerate.

If the coal sludge resulting from the treatment of coking coal is treated by the process according to the invention, the ash content can be reduced by less than 12% by the process according to the invention, so that the resulting agglomerate is also suitable for coking. This option is very important for thermal power plants.

The process according to the invention is illustrated in the drawing by a schematic diagram. Coal sludge containing about 30% by weight of dry matter and about 35 to 40% by weight of tailings, based on dry matter, is pumped from settling tank 2 by pump 13 via heat exchanger 4 to mixer 5. Optionally, pulverized coal from tank 3 and / or The coal sludge is agglomerated in a mixing reactor 16 into which steam is introduced tangentially and, secondly, from the storage tank 2 by a pump 12 a crude tar or, optionally, fuel oil or tar oil preheated in a heat exchanger 6 and containing 3% by weight. hard coal pitch. It is convenient to introduce into the mixing reactor 6 the oil sprayed into the valve controlled by the valve 16. The agglomerate prepared in the mixing reactor 6 and the tailings slurries are recirculated through the heat exchanger 6, then introduced into the countercurrent separator 7 where they are separated. The product taken from the bottom of the countercurrent separator consists of an agglomerate of coal with oil, the product taken from above is a tailings in the form of a slurry. The agglomerate triggering the upstream separator 2 ^is dewatered in the mechanical separator 9 and conveyed by a conveyor for further use or storage. Tailings triggering countercurrent separator 2 ⁱⁿ mixer 2 is mixed-VA with flocculant from reservoir 22./ then fed to a settler from the tailings therefrom containing about 40% by weight moisture pump 15 is conveyed to the drier not shown. The water overflowing from the settler 11 and almost free of slurry is passed through the valve 19 and the pump 14 partly to the upstream separator 2 ^and partly recycled through the valve 17 to coal coal (not shown).

The filtrate from the mechanical separator 2 ^is recirculated via the valve 18 again to the water circulation circuit.

The process according to the invention will be explained in the following by means of several examples, which are not intended to limit the invention to the said compounds. Unless otherwise indicated, individual amounts are in% by weight.

He did

The coal slurry with a dry matter content of 250 g / liter and a non-combustible residue of 35% is passed through a heat exchanger in an amount of 4 liters / min to the mixer 5. Fuel oil containing 3% coal pitch, light fuel oil F60 / 130 it is added in an amount of 100 g / min to the coal sludge preheated to 50 to 60 ° C. The viscosity of the fuel oil is -140.10 m / s at

CS 266 318 B2 ° C, the softening temperature of pitch dissolved in fuel oil is 85 to 95 ° C. Intensive mixing of the coal sludge and the added oil is carried out by tangentially introducing steam, the oil being sprayed with the steam. The overpressure of the saturated water vapor used for mixing is 0.1 MPa. The agglomerate formed in the mixing reactor and the tailings slurry to be separated are passed through a heat exchanger to a countercurrent separator whose bottom product is a coal-oil agglomerate while the upper product is tailings in the form of a slurry. The agglomerate triggering the separator relieves the water in the vacuum mold and transports it to other uses or storage (com. The amount of agglomerate formed is 0.95 to 1.0 kg / min and its composition is as follows:

water content 9 % solids content . 80 % oil content 11 % unburnable residue 17 %

The tailings leaving the separator are mixed in the mixer with the flocculant, then fed to a settler and therefrom the tailings having a moisture content of 40% are fed to a drier. The amount of tailings is 420 to 450 g / min and its moisture content is 40 to 42%.

170 to 180 g of dry tailings contain 1.2 to 1.3% oil, the measured carbon content is 3 to 4% and the non-combustible residue is 87 to 89%. The settler water, which is practically free of sludge, and the filtrate from the separator are fed back into the water system.

Example 2

The method is analogous to that described in Example 1, but instead of fuel oil containing 3% coal pitch, an equal amount of tar oil containing 10% coal pitch and 0.01% sodium dodecylsulfonic acid, based on dry coal sludge content, is added.

The amount of agglomerate formed is 1050 g / min and its composition is as follows:

water content 9.5% solids content 80% oil content 10.5% non-combustible residue 17%

The amount of tailings produced is 450 g / min and its water content is 43%.

Example 3

The procedure is identical to that described in Example 1 except that 60 g / min of the finished agglomerate of the following composition is added to the starting coal sludge:

water content 8.2% solids content 75% oil content 16. unburnable residue 12.4% The amount of agglomerate formed is 1.1 kg / min and its composition is this;

% water content

solids content 75% oil content 16% unburnable residue 13.5%

The amount of tailings is 480 g and its water content is 43 to 44%. Oil content in dry matter

CS 266 318 В?

it is 1.3%, the measured carbon content is 4.0% and the amount of non-combustible residue is 88%.

Example 4

The method is the same as that described in Example 1, except that the starting coal sludge m.4 has a low ash content 25. Centrifuge is used for dehydration nec.

The amount of agglomerate formed is 150g / min and its composition is as follows:

water content 10 % solids content 80 % oil content 10 % unburnable residue 10 % When the starting coal suitable for the preparation of blast furnace coke, the agglomerate formed also coking quality.

The quantity of tailings is 380 g / min and its water content is 41%. 1.2 to 1.3% dry matter in the tailings is oil, the carbon content of the combustible tailings is 3.5 to 4.0, the non-combustible residue is 91 to 91.5%.

If the process according to Examples 1 to 3 is operated without direct mixing with steam, it is necessary to produce a product of the same quality by 22% and to work according to Example 4 30% more energy for mixing.

Example 5

If Example 2 is followed, except that a polyoxyethylene derivative (Brij 35) of 0.05% by weight of the solids in the coal slurry is used as the surfactant.

The amount of agglomerate formed is 1.00 to 1.03 kg / min and its composition is as follows:

water content 8% solids content 81% oil content 14 8 non-combustible residue 14%

The amount of waste generated is 400 g / min and contains 40% water, 1.5% oil on dry weight, 3.2 to 3.5% carbon, non-combustible residue 91 to 92%.

Example 6

The procedure is analogous to Example 1, except that 25 to 40% by volume of air compressed to the same pressure was added to water vapor at a pressure of 0.2 MPa for mixing and atomizing the oil component, which significantly improves separation. of the agglomerate formed.

The sintering temperature is 90 ° C. Soy lecithin in 0.01% aqueous solution is added as a nonionic surfactant.

The amount of agglomerate formed is 1.00 to 1.05 kg / min and has the following composition:

water content 9? solids content 81% oil content 10 Я unburnt residue 12% явяваижж · ”'A Wf- U .ÍilLMlMiMi»

CS 266 318 B2

The amount of waste is 440 g / min and contains 45% water, 1.8% oil based on dry matter, carbon content 4.0 to 4.2%, non-combustible residue 89.5 to 91%.

Example 7

The procedure is as in Example 6, except that sodium dodecylsulfonate is added as the surfactant, and as a sintering agent a tar with a viscosity of 5.10 ^-5 m ² at an agglomeration temperature of 25 ° C obtained by low-temperature carbonization of hard coal.

The agglomerate is produced in an amount of 1.00 to 1.5 kg / min and has the following composition:

water content oil content

9.5%

9.5% solids content 82% non-combustible residue 11.5%

Waste separated at 450 g / min contains 20% oil on dry weight, 3.8 to 4.0% carbon, non-combustible residue 90

OBJECT OF THE INVENTION

Claims (5)

A process for producing an agglomerate from aqueous coal sludge having a dry matter content of 150 to 300 g per liter, wherein the dry matter comprises 30 to 40% by weight of a non-combustible material and wherein the coal particles have a particle size of up to 0.5 inm. precipitate and separate the precipitate, characterized in that the coal sludge is mixed with fuel oil or tar oil containing 1 to 10 L, preferably 2 to 4% by weight of coal pitch, or with crude tar, in an amount of 25 g per liter of coal sludge, the mixture is stirred at 20 to 90 ° C with water vapor at an overpressure of at least 0.02 MPa, and the moisture of the agglomerate after separation from the tailings is reduced to a maximum of 10%. 2. A process according to claim 1, characterized in that pulverized coal or the finished agglomerate is added to the coal sludge in an amount of 50 to 500 g per 1000 g of the mixture. 3. A process according to claim 1, wherein 0.01 to 1.0% by weight, based on the dry matter content, of an ionic surfactant consisting of alkali metal sulfonated aliphatic and aromatic compounds or a nonionic surfactant is added to the mixture. from the group consisting of polyoxyethylene derivatives and plant lecithins. 4. The method of claim 1 wherein air is introduced into the mixture simultaneously with the steam. 5. A method according to claim 1, wherein the oil is injected into the coal sludge by means of mixing steam.