阅读说明：本技术 煤系高岭土多段悬浮煅烧生产高白度煅烧高岭土的方法 (Method for producing high-whiteness calcined kaolin by multi-stage suspension calcination of coal-series kaolin ) 是由 李艳军 袁帅 谢瑞琦 韩跃新 高鹏 于 2020-07-29 设计创作，主要内容包括：煤系高岭土多段悬浮煅烧生产高白度煅烧高岭土的方法,按以下步骤进行：(1)将煤系高岭土破碎磨细制成粉料；(2)粉料输送到悬浮脱水煅烧炉进行脱水反应；(3)进入第一旋风分离器经旋风分离后进入悬浮脱羟煅烧炉,进行脱羟反应；(4)进入第二旋风分离器经旋风分离后进入悬浮脱碳煅烧炉进行脱碳反应；(5)进入第三旋风分离器经旋风分离后进入一级冷却器,与空气逆流换热；(6)进入二级冷却器与空气逆流换热形成高白度煅烧高岭土。本发明工艺流程简单,设备及系统运行稳定,处理量大,单位处理量的能耗及成本低,产品性质易控制,易实现设备大型化。(The method for producing the high-whiteness calcined kaolin by multistage suspension calcination of the coal-series kaolin comprises the following steps: (1) crushing and grinding coal series kaolin into powder; (2) conveying the powder to a suspension dehydration calciner for dehydration reaction; (3) entering a first cyclone separator, entering a suspension dehydroxylation calcining furnace after cyclone separation, and carrying out dehydroxylation reaction; (4) entering a second cyclone separator, carrying out cyclone separation, and then entering a suspension decarburization calciner for decarburization reaction; (5) entering a third cyclone separator, entering a first-stage cooler after cyclone separation, and performing countercurrent heat exchange with air; (6) and then the calcined kaolin enters a secondary cooler to perform countercurrent heat exchange with air to form the high-whiteness calcined kaolin. The invention has the advantages of simple process flow, stable operation of equipment and a system, large treatment capacity, low energy consumption and cost of unit treatment capacity, easy control of product properties and easy realization of large-scale equipment.)

1. A method for producing high-whiteness calcined kaolin through multistage suspension calcination of coal-series kaolin is characterized by comprising the following steps:

(1) crushing coal series kaolin until the particle size is less than or equal to 15mm, then grinding until the particle size is less than 0.038mm, and preparing into powder;

(2) continuously conveying the powder to a suspension dehydration calciner through a screw feeder; the bottom of the suspension dehydration calcining furnace is provided with a first burner and a gas inlet, the top of the suspension dehydration calcining furnace is provided with a feed inlet, and the upper part of the suspension dehydration calcining furnace is provided with a discharge outlet communicated with a first cyclone separator; introducing coal gas into the first combustor, introducing air into a gas inlet of the suspension dehydration calciner, and starting the flue gas generated by the first combustor to enter the suspension dehydration calciner; the powder entering the suspension dehydration calciner is in a suspension state under the action of air flow, and is heated to 200-300 ℃ by flue gas to carry out dehydration reaction, so that attached water on the surface of the powder is removed; the solid material formed after the dehydration reaction is dehydrated material; the dehydrated materials are discharged from a discharge hole of the suspension dehydration calciner along with the flue gas;

(3) the dehydrated material discharged from the suspension dehydration calciner enters a first cyclone separator, and the dehydrated material subjected to cyclone separation is discharged from a discharge hole of the first cyclone separator and enters the suspension dehydroxylation calciner; the bottom of the suspension dehydroxylation calcining furnace is provided with a second burner and a gas inlet, the top of the suspension dehydroxylation calcining furnace is provided with a feed inlet, and the upper part of the suspension dehydroxylation calcining furnace is provided with a discharge outlet communicated with a second cyclone separator; introducing coal gas into the second combustor, introducing air into a gas inlet of the suspension dehydroxylation calciner, and starting flue gas generated by the second combustor to enter the suspension dehydroxylation calciner; the dehydrated material entering the suspension dehydroxylation calciner is in a suspension state under the action of airflow, and is heated to 700-900 ℃ by smoke gas for dehydroxylation reaction, so that kaolin in the dehydrated material is changed into metakaolin; the solid material formed after the dehydroxylation reaction is a dehydroxylation material; the dehydroxylation material is discharged from a discharge hole of the suspension dehydroxylation calciner along with the flue gas;

(4) the dehydroxylation materials discharged from the suspension dehydroxylation calciner enter a second cyclone separator, and the dehydroxylation materials subjected to cyclone separation are discharged from a discharge hole of the second cyclone separator and enter the suspension decarburization calciner; the bottom of the suspension decarburization calcining furnace is provided with a third burner and a gas inlet, the top of the suspension decarburization calcining furnace is provided with a feed inlet, and the upper part of the suspension decarburization calcining furnace is provided with a discharge outlet communicated with a third cyclone separator; introducing coal gas into the third combustor, blending air and nitrogen into a gas inlet of the suspension decarburization calciner, and starting flue gas generated by the third combustor to enter the suspension decarburization calciner; wherein the volume flow ratio of air to nitrogen is 1 (1-2); the dehydroxylation material entering the suspension decarburization calciner is in a suspension state under the action of air flow and is heated to 850-950 ℃ by flue gas for decarburization reaction; taking a solid material formed after the decarburization reaction as a decarburization material; discharging the decarbonized materials along with flue gas from a discharge hole of the suspension decarbonization calcining furnace;

(5) the decarbonized material discharged from the suspension decarbonization calcining furnace enters a third cyclone separator, and the decarbonized material subjected to cyclone separation is discharged from a discharge hole of the third cyclone separator and enters a primary cooler; the top of the first-stage cooler is provided with a feed inlet, the lower part of the first-stage cooler is provided with an air inlet communicated with the first air compressor, the upper part of the first-stage cooler is provided with an air outlet, and the bottom of the first-stage cooler is provided with a discharge outlet communicated with the second-stage cooler; starting a first air compressor to blow air into the primary cooler, and performing countercurrent heat exchange on the decarburized material and the air; when the temperature of the decarbonized material is reduced to 150-200 ℃, a primary cooling material is formed and discharged from a discharge hole of the primary cooler;

(6) the primary cooling material discharged from the primary cooler enters a secondary cooler; the top of the secondary cooler is provided with a feed inlet, the lower part of the secondary cooler is provided with an air inlet communicated with a second air compressor, the upper part of the secondary cooler is provided with an air outlet, and the bottom of the secondary cooler is provided with a discharge outlet; starting a second air compressor to blow air into the secondary cooler, and performing countercurrent heat exchange on the primary cooling material and the air; when the temperature of the primary cooling material is reduced to be less than or equal to 50 ℃, the formed high-whiteness calcined kaolin is discharged from a discharge hole of the secondary cooler.

2. The method for producing high-whiteness calcined kaolin through multistage suspension calcination of coal-based kaolin according to claim 1, characterized in that in the step (1), the part with the particle size of less than or equal to 0.002mm accounts for 90-95% of the total mass during grinding, and is prepared into powder.

3. The method for producing high-whiteness calcined kaolin through multistage suspension calcination of coal-based kaolin according to claim 1, characterized in that in the step (2), the retention time of the powder in the suspension dehydration calciner is 2-10 min.

4. The method for producing high-whiteness calcined kaolin through multistage suspension calcination of coal-based kaolin according to claim 1, characterized in that in the step (3), the retention time of the dehydrated materials in the suspension dehydroxylation calcining furnace is 10-30 min.

5. The method for producing high-whiteness calcined kaolin through multistage suspension calcination of coal-based kaolin according to claim 1, characterized in that in the step (4), the retention time of the dehydroxylation material in the suspension decarburization calcining furnace is 40-90 min.

6. The method for producing high-whiteness calcined kaolin through multistage suspension calcination of coal-based kaolin according to claim 1, characterized in that in the step (6), after the primary cooling material and air perform countercurrent heat exchange, hot air after heat exchange is introduced into an air inlet of a suspension dehydration calciner.

7. The method for producing high-whiteness calcined kaolin through multistage suspension calcination of coal-series kaolin according to claim 1, characterized in that the whiteness of the high-whiteness calcined kaolin is 90-95%.

8. The method for producing high-whiteness calcined kaolin through multistage suspension calcination of coal-based kaolin according to claim 1, characterized in that the part of the high-whiteness calcined kaolin with the particle size of less than or equal to 0.002mm accounts for 90-95% of the total mass.

Technical Field

The invention belongs to the technical field of mineral processing, and particularly relates to a method for producing high-whiteness calcined kaolin through multistage suspension calcination of coal-series kaolin.

Background

Kaolin is one of four non-metal ores, is used as an important industrial basic raw material, and can be widely applied to multiple industries such as ceramics, papermaking, coatings, rubber, plastics, building materials and the like. With the continuous exploitation of high-grade common kaolin minerals, raw ores for processing and producing refined kaolin meeting industrial requirements are increasingly deficient. China has abundant coal-series kaolin resources, the kaolin content of which is usually more than 90 percent, and the kaolin has the characteristics of stable ore bed, convenient mining, excellent texture and the like, and is a high-quality kaolin resource. But at present, coal-series kaolin is not effectively utilized in China. Therefore, the method has important strategic significance for efficiently removing water and organic matters in the coal-series kaolin, improving the whiteness of the finished product and obtaining a high-quality calcined kaolin product.

Patent CN201510755157.X discloses a coal-series kaolin whitening method, which comprises the steps of adding charcoal powder with the fineness of more than 2000 meshes into coal-series kaolin powder, calcining, keeping the temperature at 800-860 ℃ for 2-4 hours, and naturally cooling to room temperature to obtain whitened coal-series kaolin; however, the whiteness of the product can only reach 85-90%, charcoal powder needs to be additionally added, the calcination heat preservation time is long, and the problems of non-uniformity of the product, complex process, high cost, low treatment capacity and heat utilization efficiency and the like exist; patent CN201610228875.6 discloses a decarbonization process of coal-series kaolin, which proposes to remove and recover carbon impurities in coal-series kaolin by crushing, grading, gravity separation of intermediate density products or ore grinding and flotation operations.

Disclosure of Invention

The invention aims to provide a method for producing high-whiteness calcined kaolin by multistage suspension calcination of coal-series kaolin, which is used for obtaining a high-whiteness calcined kaolin product by means of the cooperation of the multistage suspension calcination and accurate regulation.

The method of the invention is carried out according to the following steps:

1. crushing coal series kaolin until the particle size is less than or equal to 15mm, then grinding until the particle size is less than 0.038mm, and preparing into powder;

2. continuously conveying the powder to a suspension dehydration calciner through a screw feeder; the bottom of the suspension dehydration calcining furnace is provided with a first burner and a gas inlet, the top of the suspension dehydration calcining furnace is provided with a feed inlet, and the upper part of the suspension dehydration calcining furnace is provided with a discharge outlet communicated with a first cyclone separator; introducing coal gas into the first combustor, introducing air into a gas inlet of the suspension dehydration calciner, and starting the flue gas generated by the first combustor to enter the suspension dehydration calciner; the powder entering the suspension dehydration calciner is in a suspension state under the action of air flow, and is heated to 200-300 ℃ by flue gas to carry out dehydration reaction, so that attached water on the surface of the powder is removed; the solid material formed after the dehydration reaction is dehydrated material; the dehydrated materials are discharged from a discharge hole of the suspension dehydration calciner along with the flue gas;

3. the dehydrated material discharged from the suspension dehydration calciner enters a first cyclone separator, and the dehydrated material subjected to cyclone separation is discharged from a discharge hole of the first cyclone separator and enters the suspension dehydroxylation calciner; the bottom of the suspension dehydroxylation calcining furnace is provided with a second burner and a gas inlet, the top of the suspension dehydroxylation calcining furnace is provided with a feed inlet, and the upper part of the suspension dehydroxylation calcining furnace is provided with a discharge outlet communicated with a second cyclone separator; introducing coal gas into the second combustor, introducing air into a gas inlet of the suspension dehydroxylation calciner, and starting flue gas generated by the second combustor to enter the suspension dehydroxylation calciner; the dehydrated material entering the suspension dehydroxylation calciner is in a suspension state under the action of airflow, and is heated to 700-900 ℃ by smoke gas for dehydroxylation reaction, so that kaolin in the dehydrated material is changed into metakaolin; the solid material formed after the dehydroxylation reaction is a dehydroxylation material; the dehydroxylation material is discharged from a discharge hole of the suspension dehydroxylation calciner along with the flue gas;

4. the dehydroxylation materials discharged from the suspension dehydroxylation calciner enter a second cyclone separator, and the dehydroxylation materials subjected to cyclone separation are discharged from a discharge hole of the second cyclone separator and enter the suspension decarburization calciner; the bottom of the suspension decarburization calcining furnace is provided with a third burner and a gas inlet, the top of the suspension decarburization calcining furnace is provided with a feed inlet, and the upper part of the suspension decarburization calcining furnace is provided with a discharge outlet communicated with a third cyclone separator; introducing coal gas into the third combustor, blending air and nitrogen into a gas inlet of the suspension decarburization calciner, and starting flue gas generated by the third combustor to enter the suspension decarburization calciner; wherein the volume flow ratio of air to nitrogen is 1 (1-2); the dehydroxylation material entering the suspension decarburization calciner is in a suspension state under the action of air flow and is heated to 850-950 ℃ by flue gas for decarburization reaction; taking a solid material formed after the decarburization reaction as a decarburization material; discharging the decarbonized materials along with flue gas from a discharge hole of the suspension decarbonization calcining furnace;

5. the decarbonized material discharged from the suspension decarbonization calcining furnace enters a third cyclone separator, and the decarbonized material subjected to cyclone separation is discharged from a discharge hole of the third cyclone separator and enters a primary cooler; the top of the first-stage cooler is provided with a feed inlet, the lower part of the first-stage cooler is provided with an air inlet communicated with the first air compressor, the upper part of the first-stage cooler is provided with an air outlet, and the bottom of the first-stage cooler is provided with a discharge outlet communicated with the second-stage cooler; starting a first air compressor to blow air into the primary cooler, and performing countercurrent heat exchange on the decarburized material and the air; when the temperature of the decarbonized material is reduced to 150-200 ℃, a primary cooling material is formed and discharged from a discharge hole of the primary cooler;

6. the primary cooling material discharged from the primary cooler enters a secondary cooler; the top of the secondary cooler is provided with a feed inlet, the lower part of the secondary cooler is provided with an air inlet communicated with a second air compressor, the upper part of the secondary cooler is provided with an air outlet, and the bottom of the secondary cooler is provided with a discharge outlet; starting a second air compressor to blow air into the secondary cooler, and performing countercurrent heat exchange on the primary cooling material and the air; when the temperature of the primary cooling material is reduced to be less than or equal to 50 ℃, the formed high-whiteness calcined kaolin is discharged from a discharge hole of the secondary cooler.

In the step 1, the part with the grain diameter of less than or equal to 0.002mm accounts for 90-95% of the total mass during ore grinding, and is prepared into powder.

In the step 2, the powder stays in the suspension dehydration calcining furnace for 2-10 min.

In the step 3, the retention time of the dehydrated material in the suspension dehydroxylation calcining furnace is 10-30 min.

In the step 3, the reaction formula of the kaolin conversion occurring in the dehydroxylation reaction is:

Al₂O₃·2SiO₂·2H₂O→Al₂O₃·2SiO₂+H₂O。

in the step 4, the retention time of the dehydroxylation material in the suspension decarburization calcining furnace is 40-90 min.

In the step 4, the main reaction formula of the decarburization reaction is:

4(CH)_n+5n O₂→4nCO₂+2nH₂O、

C+O₂→CO₂and

4FeS₂+11O₂→2Fe₂O₃+8SO₂。

in the step 3, the gas separated by the first cyclone separator enters a dust removing device, and is discharged from a chimney after dust removal.

In the step 4, the gas separated by the second cyclone separator enters a dust removing device.

In the step 5, the gas separated by the third cyclone separator enters a dust removing device.

In the step 5, after the decarbonized material and air are subjected to countercurrent heat exchange, the temperature of the heat-exchanged hot air is 600-700 ℃, and the hot air is introduced into an air inlet of the suspension dehydroxylation calciner.

In the step 6, after the primary cooling material and the air perform countercurrent heat exchange, the hot air after heat exchange is introduced into the air inlet of the suspension dehydration calciner.

The whiteness of the high-whiteness calcined kaolin is 90-95%.

The part of the high-whiteness calcined kaolin with the particle size of less than or equal to 0.002mm accounts for 90-95% of the total mass.

Compared with the existing method for decarbonizing and whitening coal series kaolin, the method has the characteristics and advantages that: the coal-series kaolin is subjected to suspension calcination by using gas, so that the heat and mass transfer efficiency is high compared with static calcination, and the problems that the static calcination process is nonuniform in material calcination and is difficult to produce kaolin products with uniform quality can be solved; particularly, a calcination method of 'subsection precise regulation' is adopted, the 'dehydration-dehydroxylation-decarburization' process of the coal-series kaolin is treated in subsection, and products with uniform properties are obtained at each stage, so that the coal-series kaolin is precisely regulated and controlled in calcination; the problems of carbon deposition and whiteness reduction in a sample caused by incomplete combustion of organic matters due to the fact that partial pressure of oxygen in a system is reduced due to water discharge in the process of calcining the coal-series kaolin are effectively solved; the heat energy is effectively recycled through cooling by the cooler twice, energy is saved, the environment is protected, and the cost is reduced.

The invention has the advantages of simple process flow, stable operation of equipment and a system, large treatment capacity, low energy consumption and cost of unit treatment capacity, easy control of product properties and easy realization of large-scale equipment.

Drawings

Fig. 1 is a schematic flow chart of a method for producing high-whiteness calcined kaolin through multistage suspension calcination of coal-based kaolin according to an embodiment of the invention.

Detailed Description

The dust removal device in the embodiment of the invention is a commercial electrostatic dust removal device.

In the embodiment of the invention, a jaw crusher is adopted for crushing.

In the embodiment of the invention, a high-pressure roller mill is adopted for grinding.

The coal-series kaolin in the embodiment of the invention contains SiO in percentage by mass₂42～46％，Al₂O₃36～39％，Fe₂O₃0.15～0.3％，CaO 0.2～0.6％，TiO₂0.1～0.4％，MgO 0.1～0.5％，K₂O 0.2～0.4％，Na₂O 0.1～0.35％，C 0.9～1.6％。