RU2223828C2 - Method of concentration of coal sludge - Google Patents

Abstract

FIELD: concentration of coal sludge at concentrating mills, processing sludge and regeneration of sludge water. SUBSTANCE: proposed method includes simultaneous delivery of oil reagent and foam agent to water-and-coal suspension and selective oil sintering of coal particles at supply of air. Sintering process is performed in sintering chamber at mixing the suspension for 2-3 min by revolving agitator at circumferential velocity of 6 m/s. Oil reagent and foam agent are introduced into suspension at weight ratio of 5:1 to 40: 1 and total amount of 0.1-0.25% of mass of dry coal. Separation of selection products is performed in floatation chamber by floatation method upon completion of mixing the suspension. EFFECT: reduced consumption of oil reagent; reduced power requirements. 1 ex

Description

The invention relates to methods for the selective concentration and separation of fine coal particles from a coal-water slurry and can be used to enrich coal sludge in processing plants, process sludge from hydraulic dumps, and recover sludge from enterprises.

The known technology of enrichment of high-ash, fine coal by the method of oil selection (OVZUMS) [1, p. 33-41], which includes: treating the suspension with a medium regulator and an oil reagent at a flow rate of 0.5-1.5%, oil selection in a modernized cell, separation of concentrate and waste in the next cell due to the aero effect without air access. The main disadvantage of this technology is the high consumption of oil reagent per 1 ton of concentrate obtained (with a concentrate output of 20%, the oil consumption is 2.5-7.5% by weight of dry concentrate). Such a consumption of oil reagent is necessary for the formation of coal-oil flocs with a high content of oil component, in order to ensure the effect of the air effect during the separation of selection products. This significantly limits the use of this method in the enrichment of sludge from ordinary coals, due to the need for a sharp increase in reagent consumption due to an increase in the fraction of the organic part in the coal, which goes into coal oil granules.

Also known is the technology for the enrichment of coal sludge [2], which includes the supply of a suspension of oil reagent (diesel fuel or its mixture with heavy oils) in an amount of 0.3-1.5%, oil agglomeration of coal particles, passing at a speed of rotation of the mixer 1600- 2400 rpm for up to 4 minutes, separation of the formed coal microagglomerates using foam flotation in the presence of a foaming agent.

The disadvantages of this method are the high consumption of oil reagent (up to 1.5%) during oil sintering of sludge and high energy consumption for mixing the suspension. The addition of a large amount of oil reagent is caused by the need to increase the number of drops of oil in the suspension to increase the likelihood of their collision with particles and to ensure that enough oil is available to completely remove all coal particles (including microparticles) into coal-oil agglomerates in a limited period of time.

The closest in essence and the achieved result is the method of separation of organic components of coal from inorganic substances contained in preformed coal-oil agglomerates [3], including:

1) mixing in water of preformed agglomerates for their destruction and the formation of a secondary aqueous suspension;

2) mixing the secondary slurry with the addition of an additional binder and the introduction of a sufficient amount of air to:

- combine individual coal particles into denser and stronger secondary agglomerates with a reduced amount of inorganic matter in them compared to preformed agglomerates;

- capture enough air bubbles inside the agglomerates to make them more buoyant compared to preformed agglomerates;

3) separation of the secondary agglomerates from the suspension.

The main disadvantage of this method is the increased consumption of oil binder, which is more than 1% by weight of dry coal. A large consumption of a binder during the agglomeration process is necessary in order, firstly, to ensure sufficiently complete extraction of coal particles in the coal-oil agglomerates, and secondly, to form a strong contact of the coal-oil agglomerates with air bubbles when transporting them to the surface of the suspension under conditions of intensive mixing and, thirdly, to maintain the necessary concentration of oil reagents in the volume of the suspension throughout the process.

These reasons for the high consumption of the binder are caused by the fact that in the known method, the processes of formation of agglomerates with air bubbles inside, their floating and accumulating on the surface of the suspension occur simultaneously and in the same apparatus. Since the implementation of these processes requires different time and speed of mixing the suspension, then for their implementation in the same apparatus it is necessary to supply an excessive amount of oil reagents to increase the rate of formation of secondary agglomerates and achieve a stable connection with air bubbles. In addition, during the transition during the agglomeration of the formed coal-oil complexes to the surface of the suspension, the concentrations of the oil reagent and solid particles decrease in its volume; therefore, an additional supply of reagents is required to maintain the process of oil agglomeration.

The objective of the invention is to reduce the consumption of oil reagent in the enrichment of coal sludge using the processes of oil sintering of coal particles and flotation of formed agglomerates.

This task is achieved in that the coal sludge enrichment process, including the simultaneous feeding of an oil reagent and a foaming agent into the water-coal slurry, the operation of selective oil agglomeration of coal particles by continuously feeding dispersed air into the slurry, the separation of selection products by flotation, is carried out in the agglomeration chamber while the suspension is mixed in flow for 2 to 3 minutes with a rotating mixer at a peripheral speed of its rotation equal to 6 m / s, while the oil reagent and foaming agent added to the slurry at a weight ratio of the reagents of from 5: 1 to 40: 1 and a total amount of 0.1-0.25% by weight of dry coal, and the separation by flotation product selection is performed in the flotation cell at the end of the stirring suspension.

When stirring the suspension under these conditions, the dispersion of oil droplets and air bubbles increases and their number increases. Upon contact of the oil droplets with bubbles, the latter are covered with an oil film, while the total surface area of the oiled bubbles is several times larger than the surface area of the oil droplets with a constant amount of it in suspension. Due to this, the number of collisions of solid particles with oiled air bubbles increases sharply. Small hydrophobic particles of coal in a collision with such bubbles are fixed on the film of oil, forming microfocuses. Oiled microbubbles and microfocuses in a collision with larger particles of coal are fixed on their surface. As a result, complexes consisting of micro bubbles, films and drops of oil and coal particles of various sizes are formed in suspension. At the same time, the consumption of oil reagent is reduced and the rate of transfer of aerocomplexes into a foam product increases when separation of flotation selection products.

The proposed method of enrichment of coal sludge is as follows. Oil reagent and foaming agent are added to the water-carbon suspension in the required amount, the suspension is stirred at high speed for a certain time while it is continuously saturated with dispersed air without foam formation on the surface of the suspension. The coal-oil aerocomplexes formed during the oil sintering process in the suspension volume are separated at the end of mixing by means of a flotation process.

Example. In laboratory conditions, coal sludge in suspension containing 70 g / l of solid phase is enriched. The solid phase of the suspension is represented by KS brand coal with an ash content of 13.5% and fineness of 0.5 mm, with a grade of 0.1 mm, equal to 67%.

A water-carbon suspension is poured into the agglomeration chamber, a stirrer is turned on, and an oil reagent - thermogas oil and a foaming agent - bottoms from the production of butyl alcohols (BBS) are added. Thermogasoil and COBS are not scarce and are used in coal processing plants as flotation reagents. The foaming agent is added in an amount of from 0.0025 to 0.03% by weight of dry coal. An increase in the consumption of the foaming agent positively affects the enrichment results and helps to reduce the consumption of the oil reagent, however, when it is added in an amount of more than 0.03%, a stable flotation foam is formed, which is difficult to dehydrate, and the foaming agent may accumulate in the circulating water.

Air enters the agglomeration chamber due to its ejection through the hollow pipe from the atmosphere and is dispersed as a result of the turbulent effect of the fluid flows on the gas phase, the kinetic energy of which is transmitted by the rotating mixer. Stirring is carried out for a predetermined time at a constant peripheral speed of rotation of the mixer equal to 6 m / s. The duration of the oil sintering process significantly affects the enrichment indices, therefore, in each case, it is necessary to determine the minimum mixing time of the suspension, the increase of which practically does not affect the final results. After mixing, the suspension is transferred to a flotation chamber and floated without the addition of reagents until the mineralization of the foam is completely stopped.

When coal sludge is enriched according to the proposed method with an oil reagent consumption of 0.18% and a blowing agent of 0.02% by weight of dry coal, a suspension mixing time of 2 minutes and a stirrer peripheral speed of 6 m / s, coal concentrate is obtained with a yield of 87.3% and ash content of 6.5% and waste ash content of 61.6%.

Thus, the enrichment of coal sludge according to the proposed method allows to reduce the consumption of oil reagents in comparison with the known method.

Sources of information

1. Elishevich A.T. Enrichment of ultrafine coals / Elishevich A.T., Ogloblin N.D., Beletsky B.C., Papushin Yu.L. - Donetsk: Donbas: 1986 - 64 p.

2. Ignasiak L., Szymocha K., Pawlak W., Kramer J. Engineering development of selective agglomeration technology. Proc. 12th International Coal Preparation Congress "New trends in coal preperation technologies and eguipment", 1994, Cracow, vol. 2, 809-816.

3. US Patent No. 4998624, cl. B 03 D 1/02, publ. 03/12/1991.

Claims (1)

A method of enriching coal sludge, including the simultaneous supply of an oil reagent and a foaming agent into a water-coal suspension, the operation of selective oil agglomeration of coal particles by continuously feeding dispersed air into the suspension, separation of the selection products by flotation, characterized in that the selective oil agglomeration operation is carried out in an agglomeration chamber at stirring the suspension for 2-3 minutes with a rotating mixer at a peripheral speed of its rotation, 6 m / s, while the oil reagent and ne oobrazovatel added to the slurry at a weight ratio of the reagents of from 5: 1 to 40: 1 and a total amount of 0.1-0.25% by weight of dry coal, and the separation by flotation product selection is performed in the flotation cell at the end of the stirring suspension.