RU2170211C1 - Method processing silica-containing raw material - Google Patents

Abstract

FIELD: technology of processing raw material. SUBSTANCE: method comprises treating silica-containing material with sulfuric acid till pulp is formed, pulp is separated into precipitate and solution, silica is precipitated from solution separated from pulp. Precipitated silica is washed and dried. Solution is treated so as to form amphoteric oxides. Sulfuric acid is used in concentration of 5-19 wt %. Silica- containing material is boron production waste or boron silicate mineral. EFFECT: utilization of boron production waste and wider range of raw materials used. 4 cl, 12 ex

Description

 The present invention relates to a technology for processing mineral raw materials and in particular relates to a method for processing silica-containing raw materials, such as borosilicate (datolite and other) minerals.

 This method is aimed at obtaining inorganic substances, in particular silica, as well as derivatives of amphoteric oxides of elements (boron, etc.) used in industry and agriculture. Silica is used as a filler in the manufacture of rubber products, polymer composites, etc., an adsorbent or catalyst in a number of technological processes in the chemical, petrochemical, food and other industries.

A known method of processing such silica-containing raw materials as apatite production by-products to produce silica, including acid processing of the raw material, followed by two-stage washing and drying to form the target product (SU, A, 856981). Moreover, as a silica-containing raw material, a nepheline sludge is used, containing, wt.%: SiO ₂ 30.4; Al ₂ O ₃ 4.26; Fe ₂ O ₃ 2.8; TiO ₂ 0.34; CaO 57.0; Na ₂ O 1,1; K ₂ O 1,2 and others. As the acids used: at the stage of processing raw materials - nitric acid with a concentration of 20-72 wt.%, And at the first stage of washing - hydrochloric acid with a concentration of 10-20 wt. % The disadvantages of this known method include the fact that the process proceeds when heated using chemically aggressive and expensive nitric acid. In addition, hydrochloric acid causes severe corrosion of technological equipment.

 There is also known a method of complex processing of silica-containing mining waste, including their processing of 20-50 wt.% Sulfuric acid to form a pulp with subsequent separation of the pulp into sediment and solution (RU 2097322). The precipitate is used to obtain silica and non-ferrous metal oxides. The solution is neutralized and precipitated by metal hydroxides of a chromium-nickel-iron composition. The disadvantage of this method is that the pulp formed during acid decomposition is characterized by a complex chemical composition, it is difficult to separate into individual components, which leads to silica contamination with undesirable impurities.

A known method of processing silica-containing borate raw materials, including its acid treatment, followed by separation from the resulting pulp of boric acid and silica (SU 1480309). The disadvantages of this method are the high decomposition temperature of the silica-containing raw materials (95-98 ^o C) and significant energy consumption for drying the production solution.

 The closest analogue in technical essence and the achieved result with respect to the claimed one is a method for processing silica-containing raw materials, including treating it with sulfuric acid to form a pulp, separating the pulp into a precipitate and a solution, precipitating silica from the solution extracted from the pulp, washing and drying the precipitated silica, and processing the solution to obtain derivatives of amphoteric oxides [RU, 97102963, A1]. The disadvantage of this method is the limited raw material base associated with the use of raw materials and waste only apatite production.

 The objective of the present invention is the expansion of the raw material base while recycling waste from the processing of silica-containing raw materials.

 The problem is solved in that in a method for processing silica-containing raw materials, including treating it with sulfuric acid to form a pulp, separating the pulp into a precipitate and a solution, precipitating silica from a solution extracted from the pulp, washing and drying the precipitated silica, and processing the solution to obtain amphoteric oxide derivatives, according to the invention, sulfuric acid is taken with a concentration of 5-19 wt.%, and waste of boron production or borosilicate mineral is used as a silica-containing raw material.

The use of borosilicate minerals as a silica-containing raw material allows us to expand the raw material base of silica. At the same time, simultaneous utilization of silica-containing waste from boron production is also possible. It is desirable to carry out the precipitation of silica either by introducing sulfuric acid to a concentration of 23-65 wt.% In the solution, or by heating the solution to 40-95 ^o C, or by cooling the solution to (-3) - (-20) ^o C.

 Obtained by the proposed method, products (silica, derivatives of amphoteric oxides, etc.) can be used in various industries.

 The proposed method is as follows, using typical technological equipment.

Silica-containing raw materials are treated with sulfuric acid with a concentration of 5-22 wt. % until pulp formation. As a silica-containing raw material, for example, boron-containing minerals can be used (datolite of the following composition, wt.%: SiO ₂ 32-34; B ₂ O ₃ 16-18; Fe ₂ O ₃ 1.0-1.3; MnO 0.5 ; CaO 37-40; MgO 1.0, etc.), waste from boron production of the following composition, wt.%: SiO ₂ 52.0 - 58.0; CaO 18-24; B ₂ O ₃ 1,5-5,0 and others, as well as other types of silica-containing raw materials.

 When using an acid with a concentration of more than 19 wt.%, Premature precipitation of silica occurs, which significantly reduces the yield of the target product due to the loss of part of the silica along with acid-insoluble sludge sludge. The use of acid with a concentration of less than 5 wt.% Is impractical due to the low speed of the process, while reducing the extraction of the target product and unreasonably increasing water consumption.

The resulting pulp is separated into a precipitate and a solution by any conventional method, and then silica is precipitated from the solution, for example, by adding sulfuric acid to a concentration of 23-65 wt.% Or by heating the solution to 40-95 ^o C without changing the concentration of sulfuric acid, and also combined exposure to sulfuric acid and heating the system to 40-95 ^o C or cooling it to (-3) - (-20) ^o C. At a concentration of sulfuric acid below 23 wt.%, the rate of deposition of silica is low, and at a concentration of sulfuric acid above 65 wt.% increased acid consumption without acceleration deposition rate. Heating the solution obtained from the pulp below 40 ^o C or above 95 ^o C is impractical due to the low deposition rate of the target product or unreasonable increase in energy costs. When silica is precipitated by the simultaneous use of sulfuric acid and cooling, using a temperature above (-3) ^o C does not reduce the cost of washing the resulting silica, and below (-20) ^o C it is impractical due to a significant increase in the viscosity of the solution and the low precipitation rate of silica. The silica formed is washed and dried using traditional methods.

 The essence of the invention is illustrated by the following examples, not exhaustive of its scope.

 Example 1

Nepheline concentrate of the following composition, wt.%: SiO ₂ 44,0; K ₂ O 7.0; TiO ₂ 0.6; MgO 0.7; P ₂ O ₅ 0.25; Al ₂ O ₃ 29.0; Na ₂ O 12.0; Fe ₂ O ₃ 2.1; MnO 0.05; CaO 1.4 and others are added with stirring in sulfuric acid with a concentration of 5 wt. % The acid treatment process is carried out for 30 minutes, after which the reaction pulp is filtered to separate acid-insoluble sludge. In the obtained filtrate, the concentration of sulfuric acid is increased to 23 wt.% By the addition of concentrated (93 wt.%) Sulfuric acid. Silica precipitated is separated by filtration, and the precipitate is washed with water. The silica content in the precipitate is 8 wt.%, And after drying under vacuum is 85 wt.%. The resulting silica is used to obtain rubber products.

Example 2
Datolite concentrate of the following composition, wt.%: SiO ₂ 32; B ₂ O ₃ 16.0; Fe ₂ O ₃ 1.0; MnO 0.5; CaO 38.5; MgO 1.0 and others are added with stirring to sulfuric acid with a concentration of 19 wt.%. The acid treatment process is carried out for 10 minutes, after which the reaction pulp is filtered to separate acid-insoluble sludge. In the obtained filtrate, the concentration of sulfuric acid is increased to 65 wt.% By the addition of concentrated (93 wt.%) Sulfuric acid. Silica precipitated is separated by filtration, and the precipitate is washed with water. The silica content in the precipitate is 8 wt.%, And after drying under vacuum is 87 wt.%. The resulting silica is used as a carrier for the benzene hydrocracking catalyst.

 The solution after precipitation of silica is used to isolate boric acid. The yield of boron (in terms of boron oxide) is 92% of the theoretical value.

 Example 3

Silica-containing waste from the production of datolite of the following composition, wt. %; SiO ₂ 56.0; CaO 20.2; B ₂ O ₃ 3,5 and others are treated with constant stirring with sulfuric acid with a concentration of 13 wt.%. The resulting reaction pulp was filtered, and the filtrate was heated to 40 ^° C. The resulting silica precipitate was washed with water and dried to obtain the desired product. The silica content in the precipitate is 9 wt.%, And after drying by sublimation, 96 wt.%. The resulting silica is used as a desiccant of gases.

 The solution after precipitation of silica is used to produce boric acid by precipitation from acidic media.

 Example 4

The method is carried out analogously to example 2, but datolite is added to a solution of sulfuric acid with a concentration of 15 wt.%, After separation of the precipitate from the resulting pulp, the solution is cooled to -3 ^o C. The precipitate after washing and convective drying contains 89 wt.% Silica. Silica is used as filling polymer-ceramic compositions.

 The solution after precipitation of silica is used to obtain boric acid.

 Example 5

 The datolite concentrate, as in Example 2, is added with stirring to sulfuric acid with a concentration of 5 wt.%. The acid treatment process is carried out for 20 minutes, after which the reaction pulp is filtered to separate acid-insoluble sludge. In the obtained filtrate, the concentration of sulfuric acid is increased to 23 wt.% By the addition of concentrated (93 wt.%) Sulfuric acid. Silica precipitated is separated by filtration, and the precipitate is washed with water. The silica content in the precipitate is 8 wt.%, And after drying under vacuum is 87 wt.%. The resulting silica is used as a carrier for the benzene hydrocracking catalyst.

 The solution after precipitation of silica is used to obtain sodium tetraborate by neutralizing it with a solution of sodium carbonate. The yield of boron (in terms of boron oxide) is 87% of the theoretical.

 Example 6

The method is carried out analogously to example 2, but the precipitation of silica is carried out at a concentration of sulfuric acid of 38 wt.%. Precipitated silica is washed with water and spray dried. Get a powder with a specific surface area of 95 m ² / g and a silica content of 87 wt.%. Silica is used as a filler for abrasive products.

 The solution after silica precipitation is used to obtain sodium tetraborate by neutralizing it with sodium hydroxide. The yield of boron (in terms of boron oxide) is 89% of the theoretical.

 Example 7

The method is carried out analogously to example 2, but the heating of the selected solution is carried out at a temperature of 95 ^o C. The precipitated silica is washed with water and subjected to convection drying. The silica content in the dried product is 92 wt.%. I use the obtained silica to obtain a desiccant.

 The solution after precipitation of silica is used to obtain boric acid by precipitation from acidic solutions at low temperatures. The yield of boron (in terms of boron oxide) is 89% of the theoretical.

 Example 8

Datolite concentrate of the following composition, wt.%; SiO ₂ 33.5; B ₂ O ₃ 17.0; Fe ₂ O ₃ 1,2; MnO 0.3; CaO 39; MgO 1.1 and others are treated with constant stirring with sulfuric acid with a concentration of 5 wt.%. The resulting reaction pulp was filtered, and the filtrate was heated to 60 ^° C. The resulting silica precipitate was washed with water and dried to obtain the desired product. The silica content in the precipitate is 9 wt.%, And after drying by sublimation, 91 wt.%. Silica is used as a carrier of insecticides.

 The solution after precipitation of silica is used to obtain boric acid. The yield of boron (in terms of boron oxide) is 93% of theoretical.

 Example 9

The method is carried out analogously to example 2, but after adding the acid to the isolated solution, the solution is cooled to a temperature of -10 ^o C. The precipitated silica is washed with water and subjected to convection drying. Get a product with a specific surface area of 35 m ² / g and a silica content in the dried product of 91 wt.%. Silica is used to produce adsorbent.

 The solution after precipitation of silica is used to obtain sodium perborates by treating it with an aqueous solution of sodium peroxide. The yield of boron (in terms of boron oxide) is 89% of the theoretical.

 Example 10

The method is carried out analogously to example 9, but after the addition of acid, silica is precipitated at a temperature of -20 ^o C. The precipitated silica is washed with water and spray dried. The content of silicon dioxide in the dried product is 96 wt.%, And the specific surface is 80 m ² / g. Silica is used as a filler for abrasive compositions.

 The solution after precipitation of silica is used to obtain boric acid. The yield of boron (in terms of boron oxide) is 90% of theoretical.

Example 11
The method is carried out analogously to example 2, but the precipitation of silica is carried out without heating the selected solution at a sulfuric acid concentration of 41 wt. % The product after washing and convective drying contains 92 wt.% Silica, which is used in the compositions of household abrasive products.

 The solution after silica precipitation is used to obtain sodium tetraborate by neutralizing it with sodium hydroxide. The yield of boron (in terms of boron oxide) is 85% of theoretical.

 Example 12

The method is carried out analogously to example 2, but the processing of the datolite concentrate is carried out with 10 wt.% Sulfuric acid, and the precipitation of silica by introducing sulfuric acid to 28 wt.% And heating the solution to 65 ^o C. The product after washing and convective drying contains 92 wt.% Silica. Silica is used as a reinforcing additive to concrete.

 The solution after precipitation of silica is used to obtain boric acid. The yield of boron (in terms of boron oxide) is 85% of theoretical

Claims (4)

 1. A method of processing silica-containing raw materials, including treating it with sulfuric acid to form a pulp, separating the pulp into a precipitate and a solution, precipitating silica from a solution extracted from the pulp, washing and drying the precipitated silica, and processing the solution to obtain amphoteric oxide derivatives, characterized in that sulfuric acid is taken with a concentration of 5-19 wt.%, and waste of boron production or borosilicate mineral is used as a silica-containing raw material.  2. The method according to claim 1, characterized in that the precipitation of silica is carried out by the introduction of sulfuric acid to a concentration of it in a solution of 23 to 65 wt.%.  3. The method according to claim 1, characterized in that the precipitation of silica is carried out by heating the solution to 40 - 95 ° C.  4. The method according to claim 2, characterized in that the precipitation of silica is carried out by cooling the solution to (-3) - (-20) ° C.