RU2329950C1 - Method of preparation of composition that contains compounds of deposited silicon dioxide and aluminium - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention may be used in chemical industry. At the first stage of method of composition preparation in vessel at first part of sodium silicate is introduced in the form of solution that has concentration in translation to SiO₂ below 15 g/l, then solution of sulfuric acid is added until at least 60% of Na₂O amount that is available in vessel is neutralised. At the second stage simultaneously solution of sulfuric acid and sodium silicate are added, additional amount of sulfuric acid is added until pH reaction mixture is obtained between 3 and 6.5, and mixture is conditioned at mixing for 1-5-30 minutes. Precipitate is flushed from Na₂SO₄. Precipitate is thinned with mechanical action, and also by addition of sodium aluminate until ratio of Al mass to SiO₂ mass of 0.0027 ÷ 0.0030 is obtained. Sulfuric acid solution is added until pH value is 6.3 ÷ 6.7. Moist precipitate is heated up to 30 ÷ 70°C and activated by passing through magnetising device with magnetic field intensity of 250 ÷ 450 kA/m, for at least 0.3 seconds. After activation, not later than after 0.5 hours, powder is dried. Suggested invention permits to prepare composition that contains compounds of deposited silicon dioxide and aluminium, which has specific surface CTAB S_CTAB 140÷240 m²/g, factor of deagglomeration by ultrasound Fd more than 11 ml, average diameter after deagglomeration with ultrasound below 2.5 mcm, which possesses property of reduced dusting.

EFFECT: allows to prepare composition that possesses property of reduced dusting.

4 cl, 2 ex

Description

The invention relates to inorganic chemistry of silicon and its compounds, and more particularly, to a method for producing a composition containing precipitated silica and aluminum compounds used as an active (reinforcing) filler of polymers, in particular elastomers, for example rubbers.

Known methods for producing precipitated silica by reacting a solution of sodium silicate and a solution of sulfuric acid, where the deposition of silicon dioxide is carried out in two stages. At the first stage, a solution of sodium silicate is first introduced into the container in an amount containing part of the total amount of sodium silicate necessary for the reaction, then a solution of sulfuric acid is added to the container. In the second stage of deposition of silicon dioxide, the rest of the total amount of sodium silicate and a solution of sulfuric acid are simultaneously added to the vessel. (R. Euler, Silica Chemistry, Part 2, M .: Mir, 1982, pp. 769-775; US Patent No. 2731326, 1956).

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и другие. В результате взаимодействия осажденного диоксида кремния и различных алюминийсодержащих катионов и поликатионов образуются разные соединения осажденного диоксида кремния и алюминия. Всякий раз неустановленность точного качественного и количественного состава алюминийсодержащих катионов и поликатионов предопределяет неустановленность точного состава и структуры композиции, содержащей соединения осажденного диоксида кремния и алюминия.A known method of producing a wet cake containing compounds of precipitated silicon dioxide and aluminum by adding sodium aluminate to a wet cake of silicon dioxide (French patent No. FR 2536380, 1984). As a result of the hydrolysis of sodium aluminate, it is known that aluminum hydroxide is formed - Al (OH) ₃ , which is an amphoteric substance and dissociates as an alkali in an acidic medium and as an acid in an alkaline medium. Upon dissociation of Al (OH) ₃ in an acidic environment, various aluminum-containing cations and polycations can be formed, for example: Al ³⁺ , Al (OH) ²⁺ ,

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and others. As a result of the interaction of precipitated silica and various aluminum-containing cations and polycations, different compounds of precipitated silica and aluminum are formed. Each time, the uncertainty of the exact qualitative and quantitative composition of aluminum-containing cations and polycations determines the uncertainty of the exact composition and structure of the composition containing the compounds of precipitated silicon dioxide and aluminum.

A known method of obtaining a composition containing compounds of precipitated silicon dioxide and aluminum, used as an active filler of polymers having a specific surface of CTAB S _becoming 140 ÷ 240 m ² / g, ultrasonic disagglomeration factor Fd is greater than 11 ml, the average diameter after ultrasonic deagglomeration is lower than 2, 5 μm, where the deposition of silicon dioxide is carried out in a tank by interacting with stirring solutions of sodium silicate and sulfuric acid in two stages, in the first of which a solution of sodium silicate is first introduced into the tank, with ERZHAN part of the required reaction total amount of sodium silicate and having a concentration in terms of SiO ₂ is below 20 g / l and then added with sulfuric acid solution until until neutralized by at least 5% by number of Na ₂ O, present in the container after that, in the second stage of deposition of silicon dioxide, a solution of sulfuric acid and a solution of sodium silicate containing the remainder of the total amount of sodium silicate are simultaneously added to the reaction mixture, so that the ratio of the amount of added sodium silicate in ereschete on SiO ₂ to the number of sodium silicate having a tank, based on the SiO ₂ was more than 4 and less than 100, is added to the reaction mixture an additional amount of sulfuric acid until the pH of the reaction medium between 3 and 6.5, the contents of the vessel was kept under stirring for 1 ÷ 60 minutes, the precipitate is separated by silica and washed by Na ₂ sO ₄ formed in the precipitation, the washed wet cake is liquefied silica mechanical action as well as the addition of sodium aluminate in an amount such that the ratio by weight s added sodium aluminate Al based on the weight of SiO ₂ in the precipitate was ÷ 0.0027 0.0030 and, moreover, by adding sulfuric acid solution so that the liquefied wet cake containing a compound of precipitated silica and aluminum, had a pH of 6, 3 ÷ 6.7, carry out the drying of this precipitate. The sodium silicate used usually has a molar ratio of SiO ₂ / Na ₂ O lying between 2 and 4. The mass concentration of the sulfuric acid solution used is preferably between 3.9% (40 g / l) and 16.2% (180 g / l) for example between 5.7% (60 g / l) and 12.1% (130 g / l). In the second precipitation step, the sodium silicate solution usually has a concentration, expressed in SiO ₂ , between 40 g / L and 330 g / L. The temperature of the reaction medium is usually between 60 and 98 ° C. (Patent RU No. 2092435, IPC СВВ 33/193, 1997). This patent provides information on the methods according to which, with respect to precipitated silica, the specific surface of CTAB, the ultrasonic disagglomeration factor and the average diameter after ultrasonic disagglomeration are determined. The indicators characterizing the specific surface of the CTAB, the ultrasonic disagglomeration factor and the average diameter after the ultrasonic disagglomeration, given below for a composition containing precipitated silicon dioxide and aluminum compounds and obtained by the claimed method, are determined by the same methods.

A known method of obtaining a composition containing compounds of precipitated silicon dioxide and aluminum, used as an active filler of polymers, in particular elastomers, for example rubbers, is closest to the claimed combination of essential features and is adopted as a prototype.

A disadvantage of the known prototype method is that the composition obtained by this method does not have the property of reduced dusting when applied. It is known that the aerosol of a composition containing compounds of precipitated silicon dioxide and aluminum is a harmful substance and according to current hygienic standards GN 2.2.5. 1313-03 refers to harmful substances of fibrogenic action, hazard class 3, with a maximum permissible concentration (MPC) in the air of the working zone of 1 mg / m ³ (GN 2.2.5. 1313-03, p. 71, No. p / p 1123), therefore, the development of a method for producing a lower dusty composition containing compounds of precipitated silicon dioxide and aluminum seems to be relevant.

The objective of the invention is to develop a method for producing a composition containing compounds of precipitated silicon dioxide and aluminum, used as an active filler of polymers having a specific surface CTAB S _becoming 140 ÷ 240 m ² / g, ultrasonic disagglomeration factor Fd greater than 11 ml, average diameter after ultrasonic disagglomeration below 2.5 microns, which has the property that, under all other identical conditions, the concentration of dust generated in the air when it is used is at least 50% lower than the concentration of dust, Braz in the air when using the composition obtained in known manner. The same conditions mentioned above, along with others, include the following conditions:

- in the preparation of comparative tests of compositions obtained by the known and claimed methods, by their dusting when used for the manufacture of a portion of the composition obtained by the known method, and a portion of the composition obtained by the claimed method, use the same prepared batch of liquefied wet sediment containing compounds of precipitated dioxide silicon and aluminum;

- equipment, devices, instruments, mode, parameters and conditions for drying wet sediments of both compositions are the same;

- the conditions for the use of both compositions under which their dust is formed are the same;

- the sampling point of dusty air when testing both compositions is the same;

- the dust concentration of both compositions is measured by the same standard method established by the "Methodological guidelines for the photometric determination of amorphous silicon dioxide in industrial dust", approved on September 10, 1991 No. 5887-91.

The problem is solved in that in the method for producing a composition containing precipitated silicon dioxide and aluminum compounds having a specific surface of CTAB S _becoming 140 ÷ 240 m ² / g, the ultrasonic disagglomeration factor Fd is greater than 11 ml, the average diameter after ultrasonic deagglomeration is lower than 2.5 μm, where the deposition of silicon dioxide is carried out in a vessel by interacting with stirring solutions of sodium silicate and sulfuric acid in two stages, in the first of which a solution of sodium silicate is first introduced into the vessel, containing part of the required direct reaction total amount of sodium silicate and having a concentration in terms of SiO ₂ lower than 15 g / l and then added with sulfuric acid solution until until neutralized at least 60% by number of Na ₂ O, present in the container, then a second step of deposition of silicon dioxide are simultaneously added to the reaction mixture solution of sulfuric acid and sodium silicate solution containing the rest of the total amount of sodium silicate so that the ratio of the amount of added sodium silicate calculated as SiO ₂ to the Included quantity TSS sodium silicate having a tank, based on the SiO ₂ it was more than 4 and less than 40 is added to the reaction mixture an additional amount of sulfuric acid until the pH of the reaction medium between 3 and 6.5, the contents of the vessel was kept under stirring for 1 ÷ 30 minutes, separated the precipitate of silica and washed by Na ₂ sO ₄ formed in the precipitation, the washed wet cake is liquefied silica mechanical action as well as the addition of sodium aluminate in an amount such that the weight ratio of added aluminate Sodium Al based on the weight of SiO ₂ in the precipitate was ÷ 0.0027 0.0030 and, moreover, by adding sulfuric acid solution so that the liquefied wet cake containing a compound of precipitated silica and aluminum, had a pH of 6,3 ÷ 6 , 7, they carry out the drying of this precipitate, it is new that a liquefied wet precipitate containing compounds of precipitated silica and aluminum and having a pH of 6.3–6.7 is heated to a temperature of 30–70 ° C before drying and then activated, according to more than 0.5 hours before drying, by passing a stream of sediment through the omagn Chiva device which provides the magnetic field at any point of a part of the male sludge stream 250 ÷ 450 kA / m and the exposure time of the magnetic field at any point of the male part of them flow at least 0.3 seconds.

Liquefied wet sediment containing compounds of precipitated silicon dioxide and aluminum, before its magnetic activation can be heated to a temperature of 40 ÷ 60 ° C, preferably up to 50 ° C.

Magnetic activation of a liquefied wet cake containing precipitated silica and aluminum compounds can be performed at least 0.1 hours before drying, preferably at least 0.01 hours before drying.

The time of exposure of the magnetic field to any point of the portion of the fluidized sludge sludge stream containing the precipitated silicon dioxide and aluminum compounds covered by the magnetizing device is set at least 2 seconds, preferably 5 seconds.

After drying, a composition is obtained which has the property that, under all other identical conditions, the concentration of dust generated in the air when it is used is at least 50% lower than the concentration of dust formed in the air when using the composition obtained in a known manner.

Aluminum-containing cations and polycations form various compounds with precipitated silica, the bonds of which are practically irreversible. The Al atom is characterized by an increased ability to form covalent bonds. In the series, for example, out of 15 cations, Al ^{3+ is} second only to Ga ³⁺ in this ability: Ga ³⁺ , Al ³⁺ , Fe ³⁺ , Cr ³⁺ , V ³⁺ , Co ²⁺ , Cu ²⁺ , Zn ²⁺ , Ba ²⁺ , Sr ²⁺ , Ca ²⁺ , Mg ²⁺ , Rb ⁺ , K ⁺ , N ⁺ . Precipitated silica is characterized by an increased tendency to form chelate compounds (chelates). The reduced dusting property when using the composition obtained by the claimed method can be explained by the fact that the above magnetic activation of a heated diluted wet cake containing precipitated silica and aluminum compounds promotes the formation of an increased amount of chelate compounds in which the ligand is attached to the Al atom by two or more covalent bonds. The resulting structures containing an increased amount of chelate compounds have features that determine reduced dusting when using the composition obtained by the claimed method. However, other properties inherent in the composition obtained in a known manner are preserved. The regulated heating of a diluted wet cake containing silicon dioxide and aluminum compounds before magnetic activation allows this process to be carried out using a reduced magnetic field without compromising the efficiency of this operation.

Examples of known and claimed methods for producing compositions containing compounds of precipitated silica and aluminum. Comparison between the compositions obtained by known and claimed methods for their dusting during use.

Example 1

Obtaining 83.6 kg of a composition containing precipitated silica and aluminum compounds by a known method and 83.6 kg of a composition containing precipitated silica and aluminum compounds by the claimed method.

To prepare the compositions using sodium silicate having a molar ratio of SiO ₂ / Na ₂ O equal to, for example, 2.96.

1600 liters of sodium silicate solution having a concentration expressed in SiO _{2 of} 6.71 g / l (0.9 wt.% Na ₂ O · 2.96 SiO ₂ ) are introduced into a container equipped with a heating system and a mixing device, and this places a part of the total amount of sodium silicate necessary for the reaction in the vessel. The contents of the container are heated to 87 ° C and then, with constant stirring, this temperature is maintained during all operations conducted in the container. Within 7.5 minutes, a solution of sulfuric acid having a mass concentration of 7% (73.2 g / l) in an amount of 77 liters is introduced into the sodium silicate solution placed in the container and this completes the first stage of deposition of silicon dioxide. At this point, 95% by weight of the amount of Na ₂ O present in the vessel has been neutralized. In the second stage of deposition of silicon dioxide, a solution of sulfuric acid having a mass concentration of 7% is simultaneously added to the tank over a period of 82 minutes, with a flow rate controlled in such a way as to maintain a pH of 8.5 ± 0.1 and 735 liters in the reaction medium a solution of sodium silicate having a concentration expressed in SiO ₂ , 197.2 g / l (22.2 wt.% Na ₂ O · 2.96 SiO ₂ ). By the end of the above simultaneous addition, the ratio of the amount of added sodium silicate in terms of SiO ₂ to the amount of sodium silicate in the tank in terms of SiO ₂ is 13.5. A solution of sulfuric acid having a mass concentration of 7% is introduced into the container for 12.5 minutes in an amount necessary to bring the pH of the reaction medium to 5.8. Maintain the reaction mass with stirring at a temperature of 87 ° C for 9 minutes. The silica precipitate is separated and washed from Na ₂ SO ₄ using a frame filter press to obtain a washed silica precipitate having a moisture content of 82 wt.% And a residual Na ₂ SO ₄ content of 1.28 wt.% (Calculated as dry sediment). Thixotropic wet cake of silicon dioxide is diluted by mechanical action, as well as by the addition of 1.29 kg of sodium aluminate (NaAlO ₂ ) and, in addition, a sulfuric acid solution having a mass concentration of 7% in an amount necessary to adjust the pH of the diluted wet sediment containing compounds of precipitated silicon dioxide and aluminum, to a value of 6.5, while the ratio of the mass of added sodium aluminate in terms of Al to the mass of SiO ₂ in the precipitate is 0.0027. All the resulting liquefied wet sediment containing the precipitated silica and aluminum compounds and having a pH of 6.5 is divided into two equal portions. Dry one of the prepared portions of a diluted wet cake containing precipitated silica and aluminum compounds and having a pH of 6.5, at a temperature of 110 ° C. to a residual moisture content of 5 wt.% In a dryer model SFD 47 of the Danish company Anhydro A / S, providing the drying process of the type "Spin Flach", and thus, in a known manner, 83.6 kg of a composition containing precipitated silica and aluminum compounds having a specific surface of CTAB S _becoming 157 m ² / g, ultrasonic disagglomeration factor F _d 19 ml are obtained , average diameter after des lomeratsii sonicated 1.7 microns. Heat the other prepared early portion of the diluted wet cake containing precipitated silica and aluminum compounds and having a pH of 6.5 to a temperature of 70 ° C by passing its stream through a pipe equipped with an external heating cable. Magnetic activation of the heated liquefied wet cake containing compounds of precipitated silicon dioxide and aluminum is carried out 0.1 hour before it begins to dry by passing the stream of this cake through a magnetizing device of the SMTP series of the Russian company ERGA, configured to create a magnetic field of 250 kA / m and at the time of exposure to a magnetic field at any point of the covered part of the flow for 5 seconds. The liquid is activated by the action of a magnetic field of a diluted wet cake containing precipitated silica and aluminum compounds at a temperature of 110 ° C to a residual moisture content of 5 wt.% In a model SFD 47 dryer of the Danish company Anhydro A / S, which provides a Spin-type drying process "Flach", and thus, the inventive method produces 83.6 kg of a reduced dusting composition containing precipitated silica and aluminum compounds having a specific surface of CTAB S _becoming 157 m ² / g, ultrasonic disagglomeration factor F _d 19 ml, average the diameter after disagglomeration by ultrasound is 1.7 microns. The above indicators characterizing the specific surface of CTAB, the ultrasonic disagglomeration factor, and the average diameter after ultrasonic disagglomeration confirm the possibility of realizing the purpose of the composition obtained by the claimed method as an active filler of polymers.

The determination of the concentration of dust generated by the use of compositions obtained by the known and claimed methods set forth in example 1. Comparison of these concentrations among themselves.

Accumulate the known and claimed methods described in example 1, the corresponding composition, each of which in an amount sufficient for the intended scale of the tests, taking into account the characteristics of the selected working area, for example, the area for hanging powdered ingredients of tire production using automatic scales such as ODSS-20, where air intake devices from the scales are connected to the duct, dusty air in the amount of 3150 m ³ / h is sucked out by the Ts4-70 fan. The dust content of the compositions in the air is determined in the cross section of the duct at a selected point in front of the fan. The concentration of dust generated by hanging the composition obtained by the known method, and the concentration of dust generated by hanging the composition obtained by the claimed method, is determined alternately at the same selected cross-sectional point of the aforementioned duct in accordance with the current “Methodological guidelines for the photometric determination of amorphous dioxide silicon in industrial dust ”, approved on September 10, 1991 No. 5887-91, providing for sampling of dusty air with its aspiration at a speed 10 l / min through an AFA-VP-20 filter, followed by measurements and calculation of dust concentrations (mg / m ³ ).

As a result, the following indicators are obtained:

- the concentration in the air of the dust of the composition obtained in a known manner, 20.6 mg / m ³ ;

- the concentration in the air of the dust of the composition obtained by the claimed method, 12.1 mg / m ³ .

From a comparison of the results, it can be seen that the concentration of dust generated by the use of the composition obtained by the claimed method is approximately 70% lower than the concentration of dust generated by the use of the composition obtained by the known method.

Example 2

Obtaining 87.6 kg of a composition containing precipitated silica and aluminum compounds by a known method and 87.6 kg of a composition containing precipitated silica and aluminum compounds by the claimed method.

1600 liters of sodium silicate solution having a concentration expressed in SiO _{2 of} 4.24 g / l (0.57 wt.% Na ₂ O · 2.96 SiO ₂ ) are introduced into a container equipped with a heating system and a mixing device, and this places a part of the total amount of sodium silicate necessary for the reaction in the vessel. The contents of the container are heated to 85 ° C and then, with constant stirring, this temperature is maintained during all operations conducted in the container. Within 5.4 minutes, a solution of sulfuric acid having a mass concentration of 7% in an amount of 43 liters is introduced into the sodium silicate solution placed in the container, and this completes the first stage of deposition of silicon dioxide. At this point, 85% by weight of the amount of Na ₂ O present in the vessel has been neutralized. In the second stage of deposition of silicon dioxide, a solution of sulfuric acid having a mass concentration of 7% is simultaneously added to the tank for 80 minutes, with a flow rate controlled in such a way as to maintain a pH of 8.9 ± 0.1 and 793 liters of solution in the reaction medium sodium silicate having a concentration expressed in SiO ₂ , 195.0 g / l (21.9 wt.% Na ₂ O · 2.96 SiO ₂ ). By the time the above-mentioned simultaneous addition ends, the ratio of the amount of added sodium silicate in terms of SiO ₂ to the amount of sodium silicate in the tank, in terms of SiO _2, is 22.8. A solution of sulfuric acid having a mass concentration of 7% is introduced into the container for 11 minutes, in an amount necessary to bring the pH of the reaction medium to 5.9. Maintain the reaction mass with stirring at a temperature of 85 ° C for 10 minutes. The silica precipitate is separated and washed from Na ₂ SO ₄ using a frame filter press to obtain a washed silica precipitate having a moisture content of 82 wt.% And a residual Na ₂ SO ₄ content of 1.28 wt.% (Calculated as dry sediment). Thixotropic wet cake of silicon dioxide is diluted by mechanical action, as well as by the addition of 1.47 kg of sodium aluminate (NaAlO ₂ ) and, in addition, a sulfuric acid solution having a mass concentration of 7% in an amount necessary to adjust the pH of the diluted wet sediment containing compounds of precipitated silicon dioxide and aluminum, to a value of 6.6, while the ratio of the mass of added sodium aluminate in terms of Al to the mass of SiO ₂ in the precipitate is 0.0030. All the resulting liquefied wet sediment containing the precipitated silica and aluminum compounds and having a pH of 6.6 is divided into two equal portions. Dry one of the prepared portions of a diluted wet cake containing precipitated silica and aluminum compounds and having a pH of 6.6, at a temperature of 110 ° C. to a residual moisture content of 6 wt.% In a dryer model SFD 47 of the Danish company Anhydro A / S, providing a spinning process of the “Spin Flach” type, and thus, in a known manner, 87.6 kg of a composition containing precipitated silica and aluminum compounds having a specific surface of CTAB S _{having become} 157 m ² / g, ultrasonic disagglomeration factor F _d 12 ml are obtained , average diameter after des lomeratsii sonicated 1.3 microns. Heat another prepared early portion of the diluted wet cake containing precipitated silica and aluminum compounds and having a pH of 6.6 to a temperature of 30 ° C by passing its stream through a pipe equipped with an external heating cable. Magnetic activation of a heated liquefied wet cake containing compounds of precipitated silicon dioxide and aluminum is carried out 0.05 hours before it begins to dry by passing a stream of this cake through a magnetizing device of the SMTP series of the Russian company ERGA, configured to create a magnetic field of 450 kA / m and at the time of exposure to a magnetic field at any point of the covered part of the flow 4.1 seconds. The liquid is activated by the action of a magnetic field of a diluted wet cake containing precipitated silica and aluminum compounds at a temperature of 110 ° C to a residual moisture content of 6 wt.% In a model SFD 47 dryer of the Danish company Anhydro A / S, which provides a Spin-type drying process Flach ", and thus, the inventive method produces 87.6 kg of a reduced dusting composition containing precipitated silica and aluminum compounds having a specific surface of CTAB S _becoming 157 m ² / g, ultrasonic disagglomeration factor F _d 12 ml, average diameter after disagglomeration by ultrasound is 1.3 microns. The above indicators characterizing the specific surface of CTAB, the ultrasonic disagglomeration factor, and the average diameter after ultrasonic disagglomeration confirm the possibility of realizing the purpose of the composition obtained by the claimed method as an active filler of polymers.

The determination of the concentration of dust generated by the use of compositions obtained by known and claimed methods described in example 2. Comparison of these concentrations among themselves.

Accumulating the known and claimed methods described in Example 2, corresponding compositions are prepared, each of which in an amount sufficient for the intended scale of testing, taking into account the characteristics of the selected working area, for example, a section for hanging powdered ingredients for tire production using VSC type weights. Above the local pumps weights are combined into a common duct, from which the dust-laden air is sucked into the fan TS4-70 amount of 1700 m ³ / hour. The dust content of the compositions in the air is determined in the cross section of the duct at a selected point in front of the fan. The concentration of dust generated by hanging the composition obtained by the known method, and the concentration of dust generated by hanging the composition obtained by the claimed method, is determined alternately at the same selected cross-sectional point of the aforementioned duct in accordance with the current “Methodological guidelines for the photometric determination of amorphous dioxide silicon in industrial dust ”, approved on September 10, 1991 No. 5887-91, providing for sampling of dusty air with its aspiration at a speed 10 l / min through an AFA-VP-20 filter, followed by measurements and calculation of dust concentrations (mg / m ³ ).

As a result, the following indicators are obtained:

- the concentration in the air of the dust of the composition obtained in a known manner, 67.1 mg / m ³ ;

- the concentration in the air of the dust of the composition obtained by the claimed method, 38.7 mg / m ³ .

From a comparison of the results, it can be seen that the concentration of dust generated by the use of the composition obtained by the claimed method is approximately 73% lower than the concentration of dust generated by the use of the composition obtained by the known method.

Claims (4)

1. The method of obtaining a composition containing compounds of precipitated silicon dioxide and aluminum having a specific surface of CTAB S _becoming 140 ÷ 240 m ² / g, ultrasonic disagglomeration factor Fd is greater than 11 ml, the average diameter after ultrasonic deagglomeration is lower than 2.5 μm, where the dioxide is deposited silicon is carried out in a vessel by interacting with stirring solutions of sodium silicate and sulfuric acid in two stages, in the first of which a solution of sodium silicate is first introduced into the vessel, containing part of the total amount of si sodium liquate and having a concentration in terms of SiO ₂ below 15 g / l, then a solution of sulfuric acid is added until at least 60% of the amount of Na ₂ O present in the vessel is neutralized, after which in the second stage deposition of silicon dioxide at the same time add to the reaction mixture a solution of sulfuric acid and a solution of sodium silicate containing the rest of the total amount of sodium silicate so that the ratio of the amount of added sodium silicate in terms of SiO ₂ to the amount of sodium silicate available in In terms of SiO _2, it was more than 4 and less than 40, add an additional amount of sulfuric acid to the reaction mass until the pH of the reaction medium is between 3 and 6.5, maintain the contents of the tank with stirring for 1 ÷ 30 min, and separate the silica precipitate and washed by Na ₂ sO ₄ formed in the precipitation, the washed wet cake is liquefied silica mechanical action as well as the addition of sodium aluminate in an amount such that the mass ratio of sodium aluminate, based on the weight of Al ₂ SiO wasp ke amounted to 0.0027 ÷ 0.0030 and, in addition, by adding a solution of sulfuric acid so that a liquefied wet cake containing compounds of precipitated silica and aluminum had a pH of 6.3 ÷ 6.7, this cake is dried, characterized in that a liquefied wet cake containing compounds of precipitated silica and aluminum and having a pH of 6.3–6.7 is heated to a temperature of 30–70 ° C before drying and then activated at least 0.5 hours before drying by passing a stream of sediment through a magnetizing device that provides the magnetic field strength at any point of the part of the sediment stream it covers is 250 ÷ 450 kA / m and the time of the magnetic field impact on any point of the part of the stream it covers is at least 0.3 s. 2. The method according to claim 1, characterized in that the liquefied wet cake containing compounds of precipitated silicon dioxide and aluminum is heated to a temperature of 40 ÷ 60 ° C, preferably up to 50 ° C, before magnetic activation. 3. The method according to claim 1 or 2, characterized in that the magnetic activation of the liquefied wet cake containing the precipitated silica and aluminum compounds is carried out at least 0.1 hours before drying, preferably at least 0.01 h before drying. 4. The method according to claim 1, or 2, or 3, characterized in that the time of exposure to a magnetic field at any point covered by the magnetizing device of the part of the stream of liquefied wet sludge containing compounds of precipitated silicon dioxide and aluminum is set at least 2 s preferably 5 s.