Method for preparing high-dispersibility white carbon black by multi-kettle series pressurized carbonization

Abstract

The present application relates to the field of inorganic non-metallic materials, and particularly relates to a method for preparing high-dispersity white carbon black by multi-kettle series pressure carbonization, which comprises the following steps: (1) taking sodium silicate with a modulus of 3.1-3.4 as raw material, and introducing carbon dioxide gas into a reaction kettle to perform carbonization reaction, and stopping the reaction when the pH of the solution is 6-9 to obtain white carbon black slurry; (4) performing filtration, washing and drying treatment on the slurry obtained in step (3) to obtain a white carbon black sample. The present application adopts the mode of adding crystal seeds and multi-kettle series pressure carbonization, which can prepare high-dispersity white carbon black product on one hand, and is beneficial to shorten the reaction time, reduce the energy consumption and improve the raw material utilization rate on the other hand, and provides a new idea for the preparation of high-dispersity white carbon black and has a good industrial prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of inorganic non-metallic materials, in particular to a method for preparing high-dispersion white carbon black by multi-kettle series pressure carbonization. BACKGROUND

[0002] Precipitated white carbon black is a widely used inorganic material with unique physical and chemical properties, such as superior stability, reinforcement, thickening and thixotropy, etc., and is widely used in rubber, silicone rubber, tires, shoe sole materials, toothpaste, papermaking, plastics and other fields; the traditional production process of white carbon black mainly includes precipitation method and gas phase method. Compared with gas phase white carbon black, the production process and equipment of precipitated white carbon black are simple, and the production cost is much lower than that of gas phase white carbon black. At present, precipitated white carbon black is the most widely used process for producing white carbon black. The process of precipitated white carbon black can be different according to different raw materials and preparation methods, and sulfuric acid, hydrochloric acid, carbon dioxide and sodium silicate are used as basic raw materials, which can be divided into acid precipitation method, carbonization method, etc.

[0003] However, in the traditional acid precipitation method for preparing high-dispersion white carbon black, most of the equipment is intermittent, which requires a large amount of equipment and limits the production output. Moreover, most of the selected strong acids, such as sulfuric acid, have a certain corrosion on the equipment, and the large amount of wastewater produced in the production contains SO42-ions which are difficult to treat and cause serious environmental pollution. At present, the state has begun to control SO42-ions and other ions in industrial wastewater. If a large amount of industrial wastewater containing SO42-ions is treated, it is a great challenge in terms of cost and technology to the current white carbon black industry. Carbonization method for preparing white carbon black has been widely concerned due to its low cost, easy availability of raw materials and no pollution emission, but it also has certain problems.

[0004] For example, the patent document with publication number CN104591195B discloses a method for preparing white carbon black by carbonization. In the above-mentioned document, water glass solution is atomized by high-pressure spray reaction tower, then in-situ reaction with carbon dioxide-containing gas in high-pressure spray reaction tower under certain pressure to prepare white carbon black slurry, and after washing and grinding, the white carbon black product is obtained by drying and granulating. The equipment requirement is high, and grinding is needed to improve the dispersity, which greatly wastes material and financial resources.

[0005] For example, the patent document with publication number CN102040225B discloses a process for preparing precipitated white carbon black by carbon dioxide decomposition. Although the above-mentioned patent document can prepare white carbon black by carbonization method, the prepared white carbon black sample cannot meet the requirement of high dispersity. SUMMARY

[0006] The present application aims to provide a method for preparing high-dispersion white carbon black by multi-reactor series pressurized carbonization, so as to solve the problems in the background art.

[0007] To achieve the above object, the present application provides the following technical solutions.

[0008] A method for preparing high-dispersion white carbon black by multi-reactor series pressurized carbonization, the preparation method comprising the following steps:

[0009] (1) Using sodium silicate with a modulus of 3.1-3.4 as raw material, prepare a sodium silicate solution with a mass fraction of 0.5%-4.5% (1# sodium silicate solution) and a sodium silicate solution with a mass fraction of 5%-15% (2# sodium silicate solution);

[0010] (2) Mix and stir the 1# sodium silicate solution with additives in a reaction kettle, and pass carbon dioxide gas to perform carbonization reaction to obtain a seed solution;

[0011] (3) Mix and stir the 2# sodium silicate solution and the seed solution obtained in step (2) in a multi-reactor series pressurized carbonization reaction kettle, then pass carbon dioxide gas into the reaction kettle to perform carbonization reaction, and obtain white carbon black slurry;

[0012] (4) Perform filtration, washing and drying treatment on the slurry obtained in step (3) to obtain a white carbon black sample.

[0013] Preferably, the additive in step (2) is any one or a combination of at least two of anionic, cationic and non-ionic surfactants, electrolytes, ammonium salts and quaternary ammonium salts; the additive is added in an amount of 0.01%-10%; and the carbonization temperature is 60-110℃.

[0014] The stirring rate is 100-600 r / min, and the end point of the carbonization reaction is that the pH value of the slurry is 6-9.

[0015] Preferably, the carbonization reaction in the multiple reactors in series in step (3) includes a pre-carbonization reaction and a main carbonization reaction; the number of reactors is n+1 (n≥2), wherein the n+1th reactor is fixed as a tail reactor, and the remaining n reactors are alternately used as pre-reaction reactors and main reaction reactors; the connection mode of the multiple reactors in series is that the sodium silicate solution is connected to all n reactors except the n+1th reactor through a pipeline; the CO2 gas pipeline is connected to the bottom of all n reactors except the n+1th reactor, and the tail gas of the n th reactor is discharged through the top of the n th reactor and connected to the bottom of the n-1th reactor and the tail reactor at the same time; in the n-1th reactor, the sodium silicate solution first completes the pre-carbonization reaction with the tail gas of the n th reactor, and then completes the main carbonization reaction with the gas introduced through the CO2 gas pipeline; the tail gas after the main carbonization reaction is used for pre-carbonization reaction in the n-2th reactor (when n=2, the tail gas after the main carbonization reaction is used for pre-carbonization reaction in the n th reactor); the slurry after the main carbonization reaction is discharged through the n+1th reactor (tail reactor), and after liquid-solid separation, washing and drying, the white carbon black product is obtained.

[0016] Preferably, the amount of the seed crystal solution added in step (3) is 5% to 50%; the stirring rate is 100 to 1000 r / min; the carbonization temperature is 60 to 110°C; the addition mode of the seed crystal solution and the 2# sodium silicate solution is to add the seed crystal solution first and then add the 2# sodium silicate solution, or to add the seed crystal solution and the 2# sodium silicate solution in any one of the co-current addition mode; and the end point of the carbonization reaction is that the pH value of the slurry is 6 to 9.

[0017] Preferably, in step (3), the total pressure in the reactor during the pre-carbonization reaction is controlled to be 0.4 to 0.6 MPa, and the pre-carbonization reaction time is 3 to 5 h; and in step (3), the total pressure in the reactor during the main carbonization reaction is controlled to be 0.6 to 0.7 MPa.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1. In the present application, the addition of additives for preparing seed crystals should control the nucleation, growth and coalescence process of white carbon black colloidal particles, which can be controlled by adjusting the reaction temperature, concentration, addition amount of the seed crystal solution, and the type and addition amount of the additive, so as to prepare white carbon black with high dispersity.

[0020] 2. In the present application, the reaction process is controlled by using the multiple reactors in series and the operation mode of the reactors, and combining with the control of the reaction pressure, so as to shorten the reaction time, improve the raw material utilization rate, and improve the dispersity of the product.

[0021] 3. In the present application, the carbonization mother liquor generated does not contain SO42+ ions, and no waste water is discharged.

[0022] 4. The method is simple to operate, can prepare high-dispersion white carbon black, is environmentally friendly, has low energy consumption and cost, and has good economic benefits. DETAILED DESCRIPTION

[0023] A method for preparing high-dispersion white carbon black by pressure carbonization in multiple reactors in series, the preparation method comprising the following steps:

[0024] Example 1

[0025] (1) Sodium silicate with a modulus of 3.1 was used as a raw material to prepare a sodium silicate solution with a mass fraction of 3% (1# sodium silicate solution) and a sodium silicate solution with a mass fraction of 6% (2# sodium silicate solution);

[0026] (2) The 1# sodium silicate solution obtained in step (1) was mixed and stirred with 0.1% of an additive (an anionic surfactant) in a reaction kettle, the stirring rate was controlled at 300 r / min, carbonization was performed at 90°C by passing in carbon dioxide gas at a flow rate of 600 mL / min until the pH value was 6, and then the passage of carbon dioxide gas was stopped to obtain a seed solution;

[0027] (3) The 2# sodium silicate solution obtained in step (1) and the seed solution obtained in step (2) were added to a multiple-reaction-kettle pressure carbonization reactor in series with the seed solution being added first and the 2# sodium silicate solution being added second, the addition was performed in n = 3 stages, each reaction kettle was first subjected to a pre-carbonization reaction and then subjected to a main carbonization reaction. The addition amount of the seed solution was controlled at 30%, the stirring rate was 600 r / min, and the temperature was 80°C; the total pressure in the kettle during the pre-carbonization reaction was controlled at 0.6 MPa, and the pre-carbonization reaction time was 4.5 h; the total pressure in the kettle during the main carbonization reaction was controlled at 0.7 MPa; and the slurry pH at the end of the carbonization reaction was 8;

[0028] (4) The slurry in the tail kettle in step (3) was subjected to filtration, washing, and drying to obtain a white carbon black sample.

[0029] The white carbon black prepared in this example had a BET of 155 m2 / g, a CTAB of 148 m2 / g, a DBP absorption value of 2.66 cm3 / g, a heating loss of 5.32%, a burning loss of 6.39%, a water-soluble salt content of 0.78%, and a dispersion grade of 9.6.

[0030] Example 2

[0031] (1) Sodium silicate with a modulus of 3.4 was used as a raw material to prepare a sodium silicate solution with a mass fraction of 2% (1# sodium silicate solution) and a sodium silicate solution with a mass fraction of 8% (2# sodium silicate solution);

[0032] (2) The 1# sodium silicate solution obtained in step (1) is mixed with 2% of an additive (non-ionic surfactant) and stirred in a reaction kettle, the stirring rate is controlled at 300 r / min, carbonation reaction is carried out at 85°C by passing in carbon dioxide gas at a flow rate of 350 mL / min until the pH value is 7.5, then the carbon dioxide gas is stopped, and a seed solution is obtained;

[0033] (3) The 2# sodium silicate solution obtained in step (1) and the seed solution obtained in step (2) are added into a multi-kettle series pressurized carbonation reaction kettle with n = 4 in a parallel flow feeding mode, each kettle first carries out pre-carbonation reaction, and then carries out main carbonation reaction. The addition amount of the seed solution is controlled at 10%, the stirring rate is 700 r / min, and the temperature is 85°C; the total pressure in the kettle is controlled at 0.4 MPa during pre-carbonation reaction, and the pre-carbonation reaction time is 3 h; the total pressure in the kettle is controlled at 0.68 MPa during main carbonation reaction; and the pH value of the slurry at the end of carbonation reaction is 7;

[0034] (4) The slurry in the tail kettle of step (3) is filtered, washed, and dried to obtain a white carbon black sample.

[0035] The white carbon black prepared in this example has a BET of 159 m2 / g, a CTAB of 153 m2 / g, a DBP absorption value of 2.35 cm3 / g, a heating loss of 5.43%, a burning loss of 4.3%, a water-soluble salt of 1.25%, and a dispersion grade of 9.5.

[0036] Example 3

[0037] (1) A sodium silicate with a modulus of 3.3 is used as a raw material to prepare a sodium silicate solution with a mass fraction of 2.5% (1# sodium silicate solution) and a sodium silicate solution with a mass fraction of 10% (2# sodium silicate solution);

[0038] (2) The 1# sodium silicate solution obtained in step (1) is mixed with 5% of an additive (electrolyte) and stirred in a reaction kettle, the stirring rate is controlled at 300 r / min, carbonation reaction is carried out at 75°C by passing in carbon dioxide gas at a flow rate of 100 mL / min until the pH value is 8.5, then the carbon dioxide gas is stopped, and a seed solution is obtained;

[0039] (3) The 2# sodium silicate solution obtained in step (1) and the seed solution obtained in step (2) are added into a multi-pot series pressurized carbonization reactor with n = 5 in the order of adding the seed solution first and then the 2# sodium silicate solution, each reactor is first subjected to pre-carbonization reaction and then to main carbonization reaction. The addition amount of the seed solution is controlled to be 15%, the stirring rate is 300 r / min, and the temperature is 90°C; the total pressure in the reactor is controlled to be 0.45 MPa during pre-carbonization reaction, and the pre-carbonization reaction time is 4 h; the total pressure in the reactor is controlled to be 0.6 MPa during main carbonization reaction; the pH of the slurry at the end of carbonization reaction is 7.5;

[0040] (4) The slurry in the tail pot of step (3) is subjected to filtration, washing and drying treatment to obtain a white carbon black sample.

[0041] The white carbon black prepared in this example has a BET of 160 m2 / g, a CTAB of 156 m2 / g, a DBP absorption value of 2.76 cm3 / g, a heating loss of 5.89%, a burning loss of 4.62%, a water-soluble salt of 0.96%, and a dispersion grade of 9.8.

[0042] Example 4

[0043] (1) A sodium silicate with a modulus of 3.15 is used as a raw material to prepare a sodium silicate solution with a mass fraction of 2% (1# sodium silicate solution) and a sodium silicate solution with a mass fraction of 9% (2# sodium silicate solution);

[0044] (2) The 1# sodium silicate solution obtained in step (1) is mixed with 4% of an additive (a cationic surfactant) and added into a reactor for stirring, the stirring rate is controlled to be 250 r / min, carbon dioxide gas is introduced at a flow rate of 200 mL / min at 70°C to perform carbonization reaction until the pH value is 7, then the introduction of carbon dioxide gas is stopped, and a seed solution is obtained;

[0045] (3) The 2# sodium silicate solution obtained in step (1) and the seed solution obtained in step (2) are added into a multi-pot series pressurized carbonization reactor with n = 6 in a parallel flow feeding mode, each reactor is first subjected to pre-carbonization reaction and then to main carbonization reaction. The addition amount of the seed solution is controlled to be 25%, the stirring rate is 400 r / min, and the temperature is 70°C; the total pressure in the reactor is controlled to be 0.5 MPa during pre-carbonization reaction, and the pre-carbonization reaction time is 4.5 h; the total pressure in the reactor is controlled to be 0.65 MPa during main carbonization reaction; the pH of the slurry at the end of carbonization reaction is 6-9;

[0046] (4) The slurry in the tail pot of step (3) is subjected to filtration, washing and drying treatment to obtain a white carbon black sample.

[0047] The white carbon black prepared in this example has a BET of 161 m2 / g, a CTAB of 153 m2 / g, a DBP absorption value of 2.57 cm3 / g, a heating loss of 6.03%, a burning loss of 5.94%, a water-soluble salt of 1.8%, and a dispersion grade of 9.5.

[0048] Example 5

[0049] (1) Sodium silicate with a modulus of 3.2 was used as a raw material to prepare a sodium silicate solution with a mass fraction of 1.5% (1# sodium silicate solution) and a sodium silicate solution with a mass fraction of 10% (2# sodium silicate solution);

[0050] (2) The 1# sodium silicate solution obtained in step (1) was mixed with 7% of an additive (quaternary ammonium salt) in a reaction kettle and stirred at a stirring rate of 200 r / min. Carbonization was carried out at a flow rate of 600 mL / min under the condition of a temperature of 60°C until the pH value reached 7.8, and then the carbon dioxide gas was stopped. A seed solution was obtained;

[0051] (3) The 2# sodium silicate solution obtained in step (1) and the seed solution obtained in step (2) were added into a multi-kettle series pressurized carbonization reaction kettle in the order of adding the seed solution first and then adding the 2# sodium silicate solution with an addition level n = 2. Each kettle was first subjected to a pre-carbonization reaction and then to a main carbonization reaction. The addition amount of the seed solution was 10%, the stirring rate was 500 r / min, and the temperature was 60°C. The total pressure in the kettle was controlled to be 0.6 MPa during the pre-carbonization reaction, and the pre-carbonization reaction time was 3.5 h. The total pressure in the kettle was controlled to be 0.69 MPa during the main carbonization reaction. The pH value of the slurry at the end of the carbonization reaction was 7.7;

[0052] (4) The slurry in the tail kettle of step (3) was subjected to filtration, washing, and drying to obtain a white carbon black sample.

[0053] The white carbon black prepared in this example has a BET of 161 m2 / g, a CTAB of 153 m2 / g, a DBP absorption value of 2.57 cm3 / g, a heating loss of 6.03%, a burning loss of 5.94%, a water-soluble salt of 1.8%, and a dispersion grade of 9.5.

[0054] Example 6

[0055] (1) Sodium silicate with a modulus of 3.35 was used as a raw material to prepare a sodium silicate solution with a mass fraction of 1% (1# sodium silicate solution) and a sodium silicate solution with a mass fraction of 6% (2# sodium silicate solution);

[0056] (2) the 1# sodium silicate solution obtained in step (1) is added into a reaction kettle together with 0.1% of an additive (ammonium salt) and mixed and stirred, the stirring speed is controlled to be 400 r / min, carbonization reaction is carried out at 90°C by passing in carbon dioxide gas at a flow rate of 10 mL / min until the pH value is 6.9, then the passing in of carbon dioxide gas is stopped, and a seed solution is obtained;

[0057] (3) the 2# sodium silicate solution obtained in step (1) and the seed solution obtained in step (2) are added into a multi-kettle series pressure carbonization reaction kettle with a series number n=3 in a parallel flow feeding mode, each kettle is first subjected to pre-carbonization reaction, and then subjected to main carbonization reaction. The addition amount of the seed solution is controlled to be 20%, the stirring speed is controlled to be 400 r / min, and the temperature is controlled to be 75°C; the total pressure in the kettle during pre-carbonization reaction is controlled to be 0.55 MPa, and the pre-carbonization reaction time is 5 h; the total pressure in the kettle during main carbonization reaction is controlled to be 0.62 MPa; and the pH value of the slurry at the end of carbonization reaction is 7.4.

[0058] (4) the slurry in the tail kettle in step (3) is subjected to filtration, washing and drying treatment, and a white carbon black sample is obtained. The white carbon black prepared in this embodiment has a BET of 160 m2 / g, a CTAB of 151 m2 / g, a DBP absorption value of 2.53 cm3 / g, a heating loss of 6.01%, a burning loss of 4.36%, a water-soluble salt of 0.59%, and a dispersion grade of 9.8.

[0059] It can be seen from the above embodiments that, by adding an additive and controlling the temperature, the sodium silicate concentration, the carbon dioxide and the sodium silicate solution parallel flow feeding rate, and the stirring speed during seed preparation and carbonization, a white carbon black sample with high dispersity can be obtained, the method is simple to operate, can prepare white carbon black with high dispersity, has no pollutant emission, is environmentally friendly, energy-saving, clean, and has low cost, and has remarkable economic benefits.

[0060] The process method of the present application is illustrated by the above embodiments, but the present application is not limited to the above process method, i.e. it does not mean that the present application must rely on the above process method to be implemented. It should be understood by those skilled in the art that any improvement on the present application, equivalent replacement and addition of auxiliary materials and operations of the materials and operations selected by the present application, and selection of specific modes, all fall within the protection scope and disclosure scope of the present application.

[0061] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing highly dispersible white carbon black by multi-kettle series pressurized carbonization, characterized in that, The preparation method comprises the following steps: (1) taking sodium silicate with a modulus of 3.1-3.4 as raw material, and preparing a sodium silicate solution with a mass fraction of 0.5%-4.5% as a 1# sodium silicate solution and a sodium silicate solution with a mass fraction of 5%-15% as a 2# sodium silicate solution; (2) adding the 1# sodium silicate solution into a reaction kettle together with an additive, mixing and stirring, and introducing carbon dioxide gas to perform carbonization reaction to prepare a seed solution; the additive is any one or a combination of at least two of anionic, cationic and non-ionic surfactants; the additive is added in an amount of 0.01%-10%; the carbonization temperature is 60-110 ℃; the stirring rate is 100-600 r / min; and the carbonization reaction endpoint is that the slurry has a pH value of 6-9; (3) mixing and stirring the 2# sodium silicate solution and the seed solution obtained in step (2) in a multi-kettle series pressurized carbonization reaction kettle, introducing carbon dioxide gas into the reaction kettle to perform carbonization reaction, and obtaining white carbon black slurry; the carbonization reaction operation in the multi-kettle series pressurized carbonization reaction kettle comprises pre-carbonization reaction and main carbonization reaction; the number of the reaction kettles is n+1, n≥2, wherein the n+1th reaction kettle is fixed as a tail kettle, and the remaining n reaction kettles are alternately used as pre-reaction kettles and main reaction kettles; the connection mode of the multi-kettle series pressurized carbonization reaction kettle is that the sodium silicate solution is connected into all the n reaction kettles except the n+1th reaction kettle through a pipeline; a CO2 gas pipeline is communicated with the bottom of all the n reaction kettles except the n+1th reaction kettle, while the tail gas of the nth reaction kettle is discharged through the top of the nth reaction kettle and simultaneously communicated with the bottom of the n-1th reaction kettle and the tail kettle; in the n-1th reaction kettle, the sodium silicate solution first completes pre-carbonization reaction with the tail gas of the nth reaction kettle, and then performs main carbonization reaction with the gas introduced through the CO2 gas pipeline; the tail gas after main carbonization reaction is subjected to pre-carbonization reaction in the n-2th reaction kettle, and when n=2, the tail gas after main carbonization reaction is subjected to pre-carbonization reaction in the nth reaction kettle; the slurry after main carbonization reaction is discharged through the n+1th reaction kettle, and after liquid-solid separation, washing and drying, the white carbon black product is obtained; (4) filtering, washing and drying the slurry obtained in step (3) to obtain a white carbon black sample.

2. The method according to claim 1, wherein the method is characterized by, In step (3), the addition amount of the seed solution is 5%-50%; the stirring rate is 100-1000 r / min; the carbonization temperature is 60-110 ℃; and the seed solution and the 2# sodium silicate solution are added in any one of the following ways: the seed solution is added first, then the 2# sodium silicate solution is added, or the seed solution and the 2# sodium silicate solution are added in a co-current manner.

3. The method for preparing high dispersibility white carbon black by multi-reactor series pressurized carbonization according to claim 1, characterized in that, In step (3), the total pressure in the kettle during pre-carbonization reaction is controlled to be 0.4-0.6 MPa, and the pre-carbonization reaction time is 3-5 h; and in step (3), the total pressure in the kettle during main carbonization reaction is controlled to be 0.6-0.7 MPa.