RU2804115C1 - Method for producing granular sorbent - Google Patents

Abstract

FIELD: sorbents.

SUBSTANCE: method for obtaining a granular sorbent from diatomite and can be used for water purification to remove highly soluble organic compounds. A method for obtaining a granular sorbent is presented, characterized in that quarry diatomite is crushed, dried, and ground, adjusted to a moisture content of 33-35 wt.%, granulated in an intensive mixer while adding diatomite powder for dusting. The resulting granules are dried at 150-200°C in a rotary kiln, then cooled, classified to obtain granules of the main fraction of 0.8-2.0 mm.

EFFECT: ability to create a method for producing a granular diatomite sorbent for water purification to remove highly soluble organic compounds.

3 cl, 1 tbl, 3 ex

Description

The invention relates to methods for producing granular sorbent from diatomite and can be used to purify water from highly soluble organic compounds.

For the use of diatomite in dynamic processes, the permeability of the adsorbent layer is important. It is possible to increase the permeability of the adsorbent layer if you use diatomite in granular form. When granulating diatomite powder, the surface accessible to adsorption must be preserved due to its high porosity, but, at the same time, the permeability of the adsorbent layer must increase due to an increase in the size of the aggregates (granules).

There is a known method for producing a sorbent for water purification in a drinking water supply system, characterized in that the flask is crushed, dried at a temperature of 150 °C, crushed, cleaned of dust by sifting, particles ranging in size from 1 to 8 mm are isolated with a residual moisture content of 2- 5 wt. % (RU 2643963, IPC B01J 20/16, B01J 20/30, 02/06/2018).

The disadvantage of this known method is the insufficient strength of the resulting particles. Granules used for water purification and water treatment must be strong enough, therefore, to increase the strength of diatomite granules, they need to be heat treated at high temperatures.

There is a known method for producing an adsorbent, in which diatomaceous earth or flask is aged for two weeks for natural drying, during which the moisture content of the rock is reduced to 20-26 wt. %, then crushed in a cone crusher to a fraction of less than 5 mm, then subjected to heat treatment in a drum furnace at 550-650 ºС. The strength of the adsorbent is 1.5-3.0 MPa (RU 2141375, IPC B01J 20/10, B01J 20/16, B01J 20/30, 11/20/1999).

The disadvantages of this known method include the lack of a spherical shape of the resulting adsorbent and high dust formation during its operation. The spherical shape of the granule improves the flowability and portioning of the material, facilitates its surface processing, provides higher packaging density and stability of the granulometric composition of the product (RU 168903, IPC B01D 39/06, 02/27/2017).

There is a known method for producing granular filter material, which consists of grinding diatomite rock to particles less than 1 mm in size, which is then classified into 3 fractions (up to 5 microns, from 5 to 100 microns and over 100 microns), having a moisture content of 15-18 wt. %, which, to regulate the properties and characteristics, are mixed in different ratios of fractions with binding additives: for example, with water, increasing the humidity of the crushed particles to 38-42 wt. %, or with substances containing carbon. A mixture of diatomite rock particles with binding additives is sent for layer-by-layer granulation in a plate granulator or fluidized bed granulator to obtain isotropic spherical granules, the average diameter of which exceeds the average equivalent diameter of crushed diatomite rock particles by at least 8 times. The resulting granules are dried and then fired at a temperature of 700-1200 °C. The size of the granules is in the range from 0.3 to 6.0 mm, the strength of the granule under uniaxial compression is at least 5.0/d _g MPa (d _g – granule diameter, mm). Technical result: improved quality of the finished product (RU 2630554, IPC B01D 39/06, B01J 20/14, 09/11/2017).

There is a known installation for the production of fractionated diatomite, which operates as follows: quarry diatomite is supplied to the ore reserve, which ensures that the material is aged for a certain time and the possibility of its uninterrupted supply for processing. Then the raw material is fed into a paddle mixer, where plasticizers can be supplied, improving the granulation process and the quality of the sorbents. The humidity of the raw materials in the paddle mixer is maintained at 44-46 wt. % and is regulated by supplying process water when the humidity drops below the specified level, or dust when the humidity is above the specified level. Dust entering the paddle mixer is collected in a group cyclone and bag filter from the gas blown through the dryer and oven. The paddle mixer ensures mixing of the incoming raw materials with the added components (water or diatomite dust). Next, the averaged raw material enters the clay grinder, in which it is additionally mixed, ensuring the homogeneity of the mass, from where it enters the press granulator, which forms granules 15-20 mm in size. Granulated diatomaceous earth enters the drying drum through a chute. Drying of raw materials in the drying drum is ensured by supplying hot air from the oven. The temperature of the gases at the inlet to the drying drum is 386 °C, the temperature of the gases at the outlet is no more than 120 °C, while the moisture content of the granules is reduced from 46 to 37 wt. %. Dried granulated diatomaceous earth is uniformly fed into a rotating kiln for firing, the firing temperature is no more than 950 °C, the outlet gas temperature is 390 °C, the firing time is no more than 45 minutes. The fired material enters the layer refrigerator, where it cools down to 70 °C. The air heated in the layer cooler enters the rotary kiln, which saves heat. The fired granules from the layer cooler are sent to the roller crusher. A roller crusher crushes calcined diatomite. The crushed product is fed for sieving into a system of screens, in which the crushed product is divided into fractions: from 0.3 to 0.7 mm, from 0.5 to 1.0 mm, from 1.0 to 3.0 mm and from 3. 0 to 5.0 mm. Material larger than 5.0 mm is returned to the roll crusher for re-crushing. Material of the fraction less than 0.3 mm is sent to a storage hopper, from where it is supplied to the grinding section in a disintegrator combined with a classifier to obtain fine particles and produce burnt powder. The use of a utility model ensures an increase in the utilization rate of raw materials and an increase in the quality of the finished product by obtaining granules of various diameters, depending on the customer’s needs, reducing dust levels and ensuring the recycling of dust generated during the processing of raw materials (RU 80930, IPC F27B 7/34, 27.02. 2009).

An energy-saving process for calcining diatomite is known, in which diatomite particles are mixed with water to form a mixture with a moisture content of 15-50%, and then compacted to form mainly spherical balls, preferably with a diameter of 1.5-20.0 mm. The resulting granular diatomite, which may also contain flux or a bleaching agent, is calcined at a temperature of 923-1290 ºC. The granulation process reduces the time required for calcination from 30-90 min to ~0.75-30 min, thereby reducing the amount of thermal energy required to calcinate a given unit of diatomite. At the same time, fine dust of good purity, as well as materials that were previously considered waste, can be processed into usable products (US 4325844, IPC B01J20/14, 04/20/82).

The disadvantages of the known methods include the use of granulation equipment, which does not allow obtaining high-density granules, as well as the use of high temperatures for heat treatment of granules, at which “vitrification” of the granules occurs (RU 176291, IPC B01D 39/06, B01J 20/28, 16.01 .2018; RU 2630554, IPC B01D 39/06, B01J 20/14, 09/11/2017), as well as dehydration and dehydroxylation of the surface, helping to reduce the number of active adsorption sites of highly soluble organic compounds on the surface of diatomite.

The essence of the proposed method is that quarry diatomite is crushed, dried and crushed, brought to a moisture content of 33-35 wt. %, granulated in an intensive mixer, adding diatomite powder for dusting, the resulting granules are dried at 150-200 ºC in a rotating oven, then cooled, classified to obtain granules of the main fraction of 0.8-2.0 mm. Diatomite powder for dusting with a particle size of less than 100 microns and a moisture content of less than 1.0 wt. % is obtained by grinding fractions of less than 0.8 mm and more than 2.0 mm in size, obtained after classifying the granules.

The technical problem to which this invention is aimed is the creation of a method for producing granular sorbent from diatomite to purify water from highly soluble organic compounds.

The use of the proposed invention provides the following technical result: increasing the performance characteristics of the sorbent and the efficiency of use of material resources.

The specified technical result is achieved by crushing quarry diatomite, drying and grinding, bringing it to a moisture content of 33-35 wt. %, granulated in an intensive mixer, adding diatomite powder for dusting, the resulting granules are dried at 150-200 ºC in a rotating oven, then cooled, classified to obtain granules of the main fraction of 0.8-2.0 mm. Diatomite powder for dusting with a particle size of less than 100 microns and a moisture content of less than 1.0 wt. % is obtained by grinding fractions of less than 0.8 mm and more than 2.0 mm in size, obtained after classifying the granules.

The applicant's analysis of the state of the art, including a search of patents and scientific and technical sources of information and identification of sources containing information about analogues of the claimed invention, made it possible to establish that the applicant had not discovered an analogue characterized by features identical to all essential features of the claimed invention.

Consequently, the claimed invention meets the “novelty” condition.

The method for producing granular sorbent is implemented as follows.

Quarry diatomite is crushed, dried and ground to increase the surface area available for the adsorption of highly soluble organic compounds, which helps achieve the stated technical result - increasing the performance characteristics of the sorbent and the efficiency of use of material resources. Grinding of quarry diatomite is possible only after preliminary operations of crushing and drying the rock, since quarry diatomite has high humidity (up to 60 wt.%) and high water absorption (up to 150 wt.%), which prevents its mechanical processing without preliminary operations of crushing and drying, since high humidity and high water absorption cause rock sticking to the working parts of production machines. Grinding quarry diatomite after preliminary operations of crushing and drying the rock helps to achieve the stated technical result - increasing the performance characteristics of the sorbent and the efficiency of using material resources.

Then the resulting diatomite powder is brought to the optimum moisture content for granulation in an intensive mixer of 33-35 wt. %: when the powder moisture content is less than 33 wt. % diatomite powder is not granulated, when the moisture content of the diatomite powder is more than 35 wt. % gluing of granules occurs, the consumption of dusting agent increases, and the yield of the main fraction of granules decreases. Bringing diatomite powder to the optimum moisture content for granulation in an intensive mixer of 33-35 wt. % allows you to achieve the stated technical result - increasing the performance characteristics of the sorbent and the efficiency of using material resources.

Diatomite powder with a moisture content of 33-35 wt. % is granulated in an intensive mixer, adding diatomaceous earth powder for dusting. Granulation of diatomaceous earth powder in an intensive mixer produces high-density granules through the use of a rotary mixing tank that continuously feeds the mixed material into the area of the rotating devices. In this case, counter flows of mixed material with a high speed difference are formed. The intensive mixer uses rotating special mixing tools and an adjustable combination device that prevents residue from sticking to the tank wall and promotes the formation of a strong vertical component of the mixture flow. Powdering of the granules is carried out to prevent the granules from sticking together by adding diatomaceous earth powder to the intensive mixer.

The finished granules are dried at 150-200 ºС in a rotating kiln, then cooled, classified to obtain granules of the main fraction of 0.8-2.0 mm, which makes it possible to achieve the stated technical result - increasing the performance characteristics of the sorbent and the efficiency of use of material resources.

Diatomite powder for dusting with a particle size of less than 100 microns and a moisture content of less than 1.0 wt. % is obtained by grinding fractions of less than 0.8 mm and more than 2.0 mm in size, obtained after classifying the granules. This makes it possible to achieve the stated technical result - increasing the performance characteristics of the sorbent and the efficiency of using material resources.

Example 1. Quarry diatomite was manually crushed to pieces less than 50 mm, then passed through a jaw crusher to obtain particles less than 4 mm in size, dried in a rotary kiln at 150 ºC to a moisture content of 1.92%, then cooled and ground in a ball mill to particle size no more than 100 microns. The diatomaceous earth powder prepared in this way was placed in a laboratory intensive mixer Eirich R02, water was added in a thin stream to the mixer at a rotation speed of the swirl tool of 264 rpm, until the moisture content was 33 wt. %, granulated at a rotation speed of the swirl tool of 2500 rpm and at a rotation speed of the mixing tank of 42 rpm, then the granules were dusted using diatomaceous earth powder as a granule duster. Dusting was carried out at a rotation speed of the swirler tool equal to 1000 rpm. The resulting granules were dried in a rotating oven with a drum speed of 2 rpm at a temperature of 150 ºС. Then the granules were heat treated in a rotating kiln with a drum speed of 2 rpm at a temperature of 550 ºC, cooled to a temperature of 21 ºC, classified using a set of sieves to obtain the main fraction - 0.8-2.0 mm. Diatomite powder for dusting with a particle size of less than 100 microns and a moisture content of less than 1.0 wt. % was obtained by grinding fractions of less than 0.8 mm and more than 2.0 mm in size, obtained after classifying the granules. The yield of the main fraction of granules was 74.70±0.31%, the consumption of diatomite powder for dusting the granules was 0.1132±0.0002 kg/kg, the moisture content of the granules was 0.30±0.01%.

Example 2. The method for producing granular sorbent was carried out in the same way as in Example 1. The prepared diatomaceous earth powder was brought to a humidity of 35 wt. %. The resulting granules were dried in a rotating oven at a temperature of 200 ºС. The yield of the main fraction of granules was 76.88±0.12%, the consumption of diatomite powder for dusting the granules was 0.1145±0.0005 kg/kg, the moisture content of the granules was 0.41±0.02%.

Example 3. The performance characteristics of samples of granular sorbent obtained in Examples 1 and 2, as well as currently used sorbents for water purification, were tested. The results are shown in Table 1.

Table 1. Parameters of sorbents with particle sizes of 0.8-2.0 mm

Options Granular sorbent Crumbs fired at 1000 ºС Example 1 Example 2 Flask Diatomite Permeability, D 1.60±0.10 1.59±0.13 0.87±0.02 1.89±0.22 Adsorption value of methylene blue, mg/g 7.60±0.85 7.65±0.75 1.05±0.15 1.28±0.08 Ultimate compressive strength, MPa 4.70±0.35 4.66±0.29 5.00-6.00 3.96±0.11

Thus, the above description indicates that the following set of conditions are met when using the claimed invention:

- the means embodying the claimed invention, when implemented, is intended to purify water from highly soluble organic compounds;

- for the claimed method, as it is characterized in the stated claims, the possibility of its implementation using the means and methods described in the application has been confirmed;

- the means embodying the claimed invention when implemented is capable of achieving the technical result envisioned by the applicant - increasing the performance characteristics of the sorbent and the efficiency of use of material resources.

Claims (3)

1. A method for producing granular sorbent, characterized in that quarry diatomite is crushed, dried and crushed, brought to a moisture content of 33-35 wt. %, granulated in an intensive mixer, adding diatomite powder for dusting, the resulting granules are dried at 150-200 ° C in a rotating oven, then cooled, classified to obtain granules of the main fraction of 0.8-2.0 mm. 2. The method according to claim 1, characterized in that diatomaceous earth powder for dusting is obtained by grinding fractions of less than 0.8 mm and more than 2.0 mm in size, obtained after classifying the granules. 3. The method according to claim 1, characterized in that diatomaceous earth powder for dusting is obtained with a particle size of less than 100 microns and a moisture content of less than 1.0 wt. %.