RU2748082C1 - Method for enrichment of kaolin raw materials and device for its implementation - Google Patents

Abstract

FIELD: non-metallic minerals enrichment.

SUBSTANCE: proposed inventions group relates to the field of enrichment of non-metallic minerals containing the mineral kaolinite in an aqueous medium and can be used to obtain concentrates suitable for use in the ceramic, metallurgical and construction industries as raw materials for the production of alumina, refractories and building materials. The method of enrichment of kaolin raw materials includes its suspension in water and separation of the treated suspension with the release of kaolinite concentrate. Before suspension, kaolin raw materials are poured into pallets in layers no more than 10 cm thick and exposed to radiation in a sealed container at a temperature of 160-180°C for 0.5-1 hours. After processing, the suspension is cooled to 40-60°C, then by adding water it is brought to the content of the solid component in the suspension to 35-45%. Radiation treatment is carried out using a device that is a hermetically sealed container with an end bayonet cover and heaters inside it, which has pressure and temperature sensors, and a safety valve. Inside the container there are horizontal rails for placing pallets with kaolin raw materials. For radiation heating of kaolin raw materials, emitters of pulsed functional ceramics (PFC) are used, tuned to radiation in the range of electromagnetic wavelengths λ≈3.3-9.6 microns.

EFFECT: ensures the level of extraction of kaolinite not lower than 92% due to preliminary changes in the physicochemical properties and structure of the original kaolinite, leading to a decrease in viscosity.

2 cl, 1 dwg, 3 tbl

Description

The invention relates to the field of enrichment of non-metallic minerals containing the mineral kaolinite in an aqueous medium and can be used to obtain concentrates suitable for use in the ceramic, metallurgical and construction industries as raw materials for the production of alumina, refractories and building materials.

Alumina refineries around the world produce high-quality metallurgical alumina primarily from low-silica bauxite, which is being depleted. In this regard, the development of technologies for producing alumina from high-silicon raw materials, in particular from kaolins, becomes urgent. In the Republic of Uzbekistan, there is the Angren kaolin deposit, which has 1.4 billion tons of kaolin on its balance sheet.

For the processing of kaolin clays of the Angren deposit to obtain commercial alumina, the All-Russian Aluminum-Magnesium Institute (VAMI) [Enrichment of secondary kaolin of the Angren deposit / A.I. Povarov, N.N. Malova, I. V. Khazanova, I. G. Bannikov // Alumina production: Collection of works by VAMI. 1969. No. 65-66. S. 183-186.] A method of sintering with limestone was proposed, the essence of which is the interaction of limestone with kaolin oxides at 1380 ° C-1400 ° C by reaction, followed by leaching of aluminum from the cake with a solution of soda.

3 (Al ₂ O ₃ .2SiO ₂ .2H ₂ O) + 17СаСО ₃ = 3Al ₂ O ₃ .5СаО + 6 (SiO ₂ .2CaO) + 6Н ₂ О + 17CO ₂

However, the authors of the sintering method note that positive economic indicators are possible only in the case of processing raw materials with an alumina content in the concentrate of at least 32% Al ₂ O ₃ . That is, the disadvantages of the above method are its limitations for processing raw kaolin clays, a significant increase in material flows, very high sintering temperatures, and the need to purify solutions from finely dispersed silicon, which require significant energy consumption.

Since the initial crude average sample of Angren kaolin is characterized by a low content of alumina Al ₂ O ₃ - 21-23% and a very high content of silica SiO ₂ - 64-65%, given the sharp increase in the cost of energy resources and the tightening of environmental requirements over the past 50 years, it is possible to make an unambiguous conclusion: all methods (alkaline, acidic) for obtaining alumina without preliminary enrichment of Angren kaolin have no prospects.

Kaolins mined from the depths, due to their specific crystal structure and high hydrophilicity, are a very difficult object for enrichment. This is due to the fact that the main and accompanying mineral components of kaolin ores have similar physical and physicochemical properties, as well as hygroscopicity and sludgeiness, which complicate both dry and water technologies of their enrichment. Therefore, standard technologies for enrichment of kaolin are applicable only at relatively low productivity, for the ceramic, oil and gas and food industries. The creation of a large-scale production for the needs of the metallurgical industry on the basis of kaolins was not created [Laboratory and semi-industrial tests of enriched secondary kaolins for the production of alumina. Report on research work by VAMI Leningrad 1960-1964].

Analysis of studies on enrichment of kaolin made it possible to formulate requirements for innovative technologies for enrichment of kaolin: scalable methods of physical impact, allowing to modify the crystal structure of the original kaolin, destroy aggregates of minerals (from 0.05 mm to 0.005 mm), minimize the intensity of the bond between kaolin particles, and as a consequence - sharply reduce the viscosity of kaolin suspensions.

In the works of [Sys O.K. Hydrothermal modification of the structure and properties of clay raw materials: dis. Cand. tech. sciences. Belgorod, 2008.158 p. Evtushenko E.I., Sysa O.K. Structural modification of clay raw materials under hydrothermal conditions // Izv. universities. North Caucasus. region. Tech. science. 2006. No. 2. Pp. 82-86.] Were studied changes in the coagulation systems of clay minerals after hydrothermal treatment. It was found that the hydrothermal treatment of clay suspensions leads to a decrease in the specific surface area and the heat of wetting of clays with water, which may also indicate the ordering of the structure of the clay material included in the suspension. Achievement of the stabilization of the properties of clay raw materials under the influence of saturated steam can be due to two factors:

- intensification of the processes of changes in the structure;

- partial dissolution of aluminosilicates and silica, and recrystallization processes through the liquid phase.

- in the process of hydrothermal treatment of kaolin, its structure changes in such a way that the intensity of interaction between its particles and, accordingly, the viscosity of suspensions decreases by 4-10 times, and the particle size increases by 10-20%;

- the preferred mode of hydrothermal treatment of kaolin is high-speed processing in an autoclave at a temperature of 200-250 ° C and a pressure of 1-4 MPa.

It was found that the hydrothermal treatment of clay suspensions leads to a decrease in the specific surface area and the heat of wetting of clays with water, which may also indicate the ordering of the structure of the clay material included in the suspension.

In patent RU 2647549 [Method for enrichment of kaolin raw materials. Authors: Arsentiev V.A. (RU), Gerasimov A.M. (RU), Dmitriev S.V. (RU), Mezenin A.O. (RU), Ustinov I.D. (RU)], which is the closest analogue (NBA), autoclave hydrothermal modification of the structure and properties of clay raw materials is used to enrich kaolin raw materials at temperatures of 180-265 ° C and a pressure of 1-5 MPa.

Considering these results from the standpoint of improving the process of wet enrichment of kaolin, it should be noted that autoclave equipment for the hydrothermal treatment of mineral raw materials and products based on it is used in the construction industry, but is expensive to manufacture and operate due to the use of high temperatures and pressures. There are significant losses in the delivery of saturated steam from the steam generator to the reactor.

The fundamental theory created at the Institute of Materials Science NPO Physics-Solntse of the Republic of Uzbekistan makes it possible to create, on the basis of pulsed functional ceramics (IFC), transducers that act directly on deformation, symmetric and asymmetric, as well as other vibrational modes of water molecules, minerals and solutions. A number of technical solutions protected by patents for inventions have been obtained using the capabilities of the IFC [US 6,251,306 B1, US 6,200,501 B1, US 5,472,720, US 5,350,927, etc.].

With optimal radiation of pulsed functional ceramics (IPC), energy conversion of the primary radiation source - certain chemical reactions of destruction of macromolecules, conglomerates of minerals occur in the entire volume simultaneously.

Based on the analysis of the research carried out, a fundamentally new technological scheme for enrichment of kaolin was developed, based on the use of radiation treatment by radiation of pulsed functional ceramics (IPC) on kaolin raw materials. Radiation radiation of pulsed infrared ceramics in the range of electromagnetic wavelengths λ≈3.3-9.6 microns affects chemically bound and free water in kaolin raw materials, which leads to disaggregation of mineral conglomerates of kaolin and subsequent wet classification by size. The main criteria in the development of the technological scheme were: obtaining the conditional concentration indicators for concentrate with the maximum possible reduction of filtration stages - minimizing the use of process water.

In the claimed method for enrichment of kaolin raw materials, including its suspension in water, and separation of the treated suspension with the release of kaolinite concentrate, which differs from NBA in that, prior to suspension, the kaolin raw materials are poured into pallets in layers no more than 10 cm thick and exposed to radiation by emitters of pulsed functional ceramics ( IFC) tuned to radiation in the range of electromagnetic wavelengths λ≈3.3-9.6 μm in a sealed container at a temperature of 160-180 ° C for 0.5-1 hour, after processing the suspension is cooled to 40-60 ° C, then, by adding water, it is brought to the content of the solid component in the suspension to 35-45%.

The technical result of the method for enrichment of kaolin raw materials is a change in the physicochemical properties and structure of the initial kaolinite, leading to a decrease in viscosity, which makes it possible to subsequently separate it with a selectivity of separation operations when extracting kaolinite not less than 92%.

A new technological scheme for enrichment of kaolin was tested on kaolin of Tashkent, Samarkand and Navoi regions of Uzbekistan (Table 1).

Samples of kaolin were detailed (up to 100 mm), then crushed to 3-2.5 mm. After moistening to 10-15% of the sample weight, the kaolin samples were placed on trays that were installed in a sealed container for radiation treatment with pulsed functional ceramics (IPC) emitters. The processing time was 0.5-1 hour, the temperature inside the container varied 150 ° C-180 ° C. After opening the container and cooling to 40-60 ° C, water was added to the sample at the rate of 35-45% solids and loaded into a scrubber-butar with sieve sizes 1.5 mm - 0.5 mm - 0.2 mm. During the separation, water was supplied to the sieves under pressure, the final S / L = 1/3. The pulp was fed for hydrocycloning, the diameter of the cyclone was 50 mm. Below is the analysis of the discharge of the hydrocyclone (tab. 2).

After filtration and drying, stable results were obtained:

- improved thixotropic properties of kaolin suspensions after radiation treatment with pulsed functional ceramics (IPC), which made it possible to increase the density of slurries subjected to concentration, and, accordingly, to reduce water consumption and the cost of dewatering the products of concentration;

- the use of radiation processing by pulsed functional ceramics (IPC) for kaolins made it possible to avoid the use of liquid glass or sodium phosphate reagents, and to exclude the consumption of flocculant reagents;

- the dispersion of kaolin during processing by radiation with pulsed functional ceramics (IPC) along the boundaries of kaolin minerals provided the best selectivity of separation operations, with the extraction of kaolinite at least 92%;

- the direct effect of radiation by pulsed functional ceramics (IPC) on kaolin is energetically more justified than the processing of kaolin in an autoclave.

The studies carried out have shown the high efficiency of kaolin radiation treatment by pulsed functional ceramics (IPC), so already at the first stage of separation using a scrubber-butar concentrates were obtained with an Al ₂ O ₃ content of 32%, which is quite suitable for acid-base methods of alumina production.

Table. 3 shows the data of experiments with kaolin raw materials of three deposits of Uzbekistan in comparison with the data of the experiments of the NBA.

From those given in table. 3 data it follows that the proposed method, due to the unique properties of the IFC, makes it possible to obtain kaolin concentrates of better quality in comparison with NBA at a lower temperature.

The applicant has not identified technical solutions identical to the present invention, which allows us to conclude that it meets the "novelty" criterion.

Thanks to the implementation of the distinctive features of the present invention in conjunction with the features given in the limiting part of the claims, new properties of the claimed subject matter are achieved.

The task of the device for the implementation of the proposed method of enrichment of kaolin raw materials is to create conditions for radiation treatment of kaolin raw materials in a sealed container at a temperature of 160-180 ° C.

The device is a hermetically sealed container with an end bayonet cover with radiation heaters inside it, which has pressure and temperature sensors, a safety valve, guides are arranged inside the container for placing trays with kaolin raw materials, and for radiation heating of the kaolin raw materials, emitters of pulsed functional ceramics (IPC) are used. for radiation in the range of electromagnetic wavelengths λ≈3.3-9.6 microns.

The possibility of implementing the device, characterized by the above set of features, as well as the possibility of implementing the invention can be confirmed by the description of the design variant of the device made in accordance with the invention, the essence of which is explained by the graphical materials.

FIG. 1 shows a cross-sectional view of a hermetically sealed container with radiation emitters inside it.

Designation of positions in the drawing:

1 - outer container body;

2 - horizontal guides for placing pallets with kaolin raw materials;

3 - pallets with kaolin raw materials;

4 - emitters of pulsed functional ceramics (IFC).

Claims (2)

1. A method for enriching kaolin raw materials, including suspending it in water and separating the treated suspension with the release of kaolinite concentrate, characterized in that, prior to suspension, the kaolin raw material is poured into pallets in layers no more than 10 cm thick and exposed to radiation in a sealed container at a temperature of 160-180 ° C for 0.5-1 hours, after processing the suspension is cooled to 40-60 ° C, then by adding water it is brought to the content of the solid component in the suspension to 35-45%. 2. A device for radiation treatment of kaolin raw materials according to claim 1, which is a hermetically sealed container with an end bayonet cover and heaters inside it, having pressure and temperature sensors, a safety valve, characterized in that horizontal guides are arranged inside the container for placing trays with kaolin raw materials, and for radiation heating of kaolin raw materials, emitters of pulsed functional ceramics (IPC) are used, tuned to radiation in the range of electromagnetic wavelength λ≈3.3-9.6 μm.

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