阅读说明：本技术 一种煤系高岭土重金属铅脱除工艺 (Coal series kaolin heavy metal lead removal process ) 是由 贾国兴 李昀霞 邢海明 罗训樵 罗一 于 2021-11-03 设计创作，主要内容包括：一种煤系高岭土重金属铅脱除工艺,属于煤系高岭土脱铅工艺技术领域,解决现有煤系高岭土中铅含量高的技术问题。本发明通过以下技术方案予以实现：一种煤系高岭土重金属铅脱除工艺,包括以下工艺步骤：1)磨粉处理；2)配浆湿磨；3)分级处理；4)酸溶处理；5)打散煅烧。与现有技术相比,本发明提高了煤系固废物资源综合利用能力,推动国内煅烧高岭土产品向技术含量高和安全环保方向发展。(A process for removing heavy metal lead from coal-series kaolin belongs to the technical field of coal-series kaolin deleading processes, and solves the technical problem of high lead content in the existing coal-series kaolin. The invention is realized by the following technical scheme: a coal series kaolin heavy metal lead removal process comprises the following process steps: 1) grinding; 2) slurry preparation and wet grinding; 3) grading treatment; 4) acid dissolution treatment; 5) scattering and calcining. Compared with the prior art, the invention improves the comprehensive utilization capacity of coal-based solid waste resources and promotes the domestic calcined kaolin product to develop towards high technical content, safety and environmental protection.)

1. A coal series kaolin heavy metal lead removal process is characterized in that: the method comprises the following process steps:

1) grinding treatment: adding the crushed coal-based kaolin ore to be treated into a vertical roller mill, and grinding the crushed coal-based kaolin ore by using the vertical roller mill under the pressure of a grinding roller of 7-8 Mpa to prepare 325-400-mesh coal-based kaolin powder;

2) slurry preparation and wet grinding: mixing the coal series kaolin powder according to the weight addition of 30-35% to obtain slurry, and wet-grinding the slurry by wet grinding equipment to obtain slurry of 4000-5000 meshes;

3) grading treatment: sequentially carrying out horizontal centrifuge treatment and disc centrifuge two-time grading treatment on the coal series kaolin slurry prepared in the step 2);

4) acid dissolution treatment: transferring the slurry obtained by grading to a sealed heatable polyurethane dispersing and stirring barrel, adding a dilute nitric acid solution with the mass fraction of 5% into the polyurethane dispersing and stirring barrel, controlling the temperature of the slurry at 80 ℃, fully stirring for 2-3 h, and then dehydrating and filtering by using a corrosion-resistant plate filter press to obtain a coal-series kaolin filter cake;

5) scattering and calcining: drying and scattering the filtered coal-series kaolin filter cake, and placing the filter cake into a rotary kiln to dynamically calcine to obtain the coal-series calcined kaolin with low lead content.

2. The coal-series kaolin heavy metal lead removal process according to claim 1, which is characterized in that: the weight ratio of the coarse materials removed by the horizontal centrifuge in the step 3) is 30-35% of the weight before removal, and the coarse materials are coal series kaolin and heavy metal lead impurity combinations; the weight ratio of the low-concentration mixed slurry removed by the disc centrifuge is 3-5% of the weight before removal, and the mixed slurry is a mixed solution of soluble heavy metal lead, coal-series kaolin and water.

3. The coal-series kaolin heavy metal lead removal process according to claim 1, which is characterized in that: the volume ratio of the dilute nitric acid solution added in the step 4) to the slurry is 0.5: 1.

4. the coal-series kaolin heavy metal lead removal process according to claim 1, which is characterized in that: neutralizing the filtrate filtered in the step 4) by using calcium carbonate.

Technical Field

The invention belongs to the technical field of a coal-series kaolin deleading process, and particularly relates to a coal-series kaolin heavy metal lead removal process.

Background

The coal-series kaolin industrial solid waste is rich in elements such as Si, Al and the like, mainly contains substances such as silicate, aluminate and the like, has a hexagonal platelet structure, high porosity and good acid and alkali resistance, and is widely applied to the fields of coating, papermaking, rubber and plastic and chemical medical treatment. Among them, latex paints for interior and exterior walls of buildings and wrapping papers for foods are most frequently in contact with human bodies.

Lead-containing emulsion paint and food paper are important sources of lead for people to contact, and lead pollution and environmental pollution and public health problems caused by lead poisoning cause close attention of the international society. Heavy metals such as lead, chromium and zinc are accumulated in vivo to generate toxicity, and damage the nervous system of a human body, so that tissues such as a hematopoietic system and a digestive system are damaged. The calcined coal series kaolin product produced by the traditional process has the problems of high lead content, product safety and the like, and cannot meet the application requirements in high-grade coatings and cosmetics. If effective solidification and reduction of the content of heavy metals are not carried out in the process of solid waste deep processing of the coal-series kaolin industry, the sustainable development of the coal-series kaolin industry in China is greatly hindered, and technical innovation and leading cannot be realized.

Disclosure of Invention

The invention provides a process for removing heavy metal lead from coal-series kaolin, aiming at overcoming the defects in the prior art and solving the technical problem of high lead content in the existing coal-series kaolin.

The invention is realized by the following technical scheme.

A coal series kaolin heavy metal lead removal process comprises the following process steps:

1) grinding treatment: adding the crushed coal-based kaolin ore to be treated into a vertical roller mill, and grinding the crushed coal-based kaolin ore by using the vertical roller mill under the pressure of a grinding roller of 7-8 Mpa to prepare 325-400-mesh coal-based kaolin powder;

2) slurry preparation and wet grinding: mixing the coal series kaolin powder according to the weight addition of 30-35% to obtain slurry, and wet-grinding the slurry by wet grinding equipment to obtain slurry of 4000-5000 meshes;

3) grading treatment: sequentially carrying out horizontal centrifuge treatment and disc centrifuge two-time grading treatment on the coal series kaolin slurry prepared in the step 2);

4) acid dissolution treatment: transferring the slurry obtained by grading to a sealed heatable polyurethane dispersing and stirring barrel, adding a dilute nitric acid solution with the mass fraction of 5% into the polyurethane dispersing and stirring barrel, controlling the temperature of the slurry at 80 ℃, fully stirring for 2-3 h, and then dehydrating and filtering by using a corrosion-resistant plate filter press to obtain a coal-series kaolin filter cake;

5) scattering and calcining: drying and scattering the filtered coal-series kaolin filter cake, and placing the filter cake into a rotary kiln to dynamically calcine to obtain the coal-series calcined kaolin with low lead content.

Further, the weight ratio of coarse materials processed and removed by the horizontal centrifuge in the step 3) is 30-35% of the weight before removal, and the coarse materials are coal series kaolin and heavy metal lead impurity combination; the weight ratio of the low-concentration mixed slurry removed by the disc centrifuge is 3-5% of the weight before removal, and the mixed slurry is a mixed solution of soluble heavy metal lead, coal-series kaolin and water.

Further, the volume ratio of the dilute nitric acid solution added in the step 4) to the slurry is 0.5: 1.

further, neutralizing the filtrate filtered in the step 4) by using calcium carbonate.

The method focuses on comprehensive utilization of coal-series kaolinite resources, and removes heavy metal lead according to the mineral composition of different coal-series kaolinite and the physical and chemical difference relationship between the heavy metal lead and the kaolinite. The ore crushing efficiency is improved and the separation of the effective components of the coal series kaolin and the impurity heavy metal is improved by a vertical mill pressurizing and efficiency improving mode; carrying out mineral heavy metal stripping by adopting a multistage grading process; the reduction and removal of the lead content in the material are realized by combining a plurality of acid dissolution filtration modes. Under the condition of ensuring that the components of the product are not changed, the method is favorable for reducing the content of heavy metal lead impurities in the coal-series kaolin, so that the lead content of the coal-series kaolin product prepared by the technical scheme is reduced to 10-30 ppm, which is 10-30% of the content of heavy metal lead in the existing coal-series kaolin. The invention improves the comprehensive utilization capacity of coal-based solid waste resources and promotes the development of domestic calcined kaolin products towards high technical content, safety and environmental protection. Meanwhile, the successful conversion of the project thoroughly solves the problem of the harm of heavy metal substances of the coal gangue solid waste minerals to the environment, and provides technical possibility for the fields of high-end cosmetics, high-end coatings and paper of coal series calcined kaolin advanced to the army.

Detailed Description

A coal series kaolin heavy metal lead removal process comprises the following process steps:

1) grinding treatment: adding the crushed coal-based kaolin ore to be treated into a vertical roller mill, and grinding the crushed coal-based kaolin ore by using the vertical roller mill under the pressure of a grinding roller of 7-8 Mpa to prepare 325-400-mesh coal-based kaolin powder; the content of heavy metal lead in the coal series kaolin ore to be treated is more than 100 ppm.

2) Slurry preparation and wet grinding: mixing the coal series kaolin powder according to the weight addition of 30-35% to obtain slurry, and wet-grinding the slurry by wet grinding equipment to obtain slurry of 4000-5000 meshes; the content of heavy metal lead in the slurry is 73.5-87.6 ppm.

3) Grading treatment: sequentially carrying out horizontal centrifuge treatment and disc centrifuge two-time grading treatment on the coal series kaolin slurry prepared in the step 2); the weight ratio of the coarse materials processed and removed by the horizontal centrifuge is 30-35% of the weight before removal, and the coarse materials are coal series kaolin and heavy metal lead impurity combinations; the weight ratio of the low-concentration mixed slurry removed by the disc centrifuge is 3-5% of the weight before removal, and the mixed slurry is a mixed solution of soluble heavy metal lead, coal-series kaolin and water. The heavy metal lead content in the coal series kaolin mud obtained by twice classification is 52.8 ppm.

4) Acid dissolution treatment: transferring the slurry obtained by grading to a sealed heatable polyurethane dispersing and stirring barrel, adding a dilute nitric acid solution with the mass fraction of 5% into the polyurethane dispersing and stirring barrel, controlling the temperature of the slurry at 80 ℃, fully stirring for 2-3 h, and then dehydrating and filtering by using a corrosion-resistant plate filter press to obtain a coal-series kaolin filter cake; the volume ratio of the dilute nitric acid solution to the slurry added is 0.5: 1. and neutralizing the filtered filtrate by using calcium carbonate. After acid dissolution treatment, the lead content is 20.3ppm, which is reduced by more than 50%.

5) Scattering and calcining: drying and scattering the filtered coal-series kaolin filter cake, and placing the filter cake into a rotary kiln to dynamically calcine to obtain the coal-series calcined kaolin with low lead content.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.