Production and application technology of calcium c

2022-10-24
  • Detail

Production and application technology of refined filler calcium carbonate from alkali recovered white mud

I. overview

alkali recovered white mud from alkaline straw pulp is a kind of paper mill waste. Due to the high content of impurities such as silica, it is not easy to calcine lime for recycling. At present, the vast majority of paper mills treat white mud only by simple outward transportation and landfilling. As a result, an enterprise needs to invest in white mud landfilling, Second, the local people and the environmental protection department will investigate the secondary pollution generated after landfilling, so the solution of the white mud problem is consistent to perplex the enterprise. After years of extensive research and design, Beijing wattmade Environmental Protection Technology Co., Ltd. has successfully opened up a way to completely solve the problem of white mud. White mud essence is made into filler grade light calcium carbonate and filled into the paper machine. At the same time, its production is industrialized and specialized. The biggest feature of this process technology is: Based on the recovery of high-quality alkali liquor and the scientific integration of white mud calcium carbonate product production

the first white mud refined filler calcium carbonate constructed by this technology in Shandong MCC Yinhe Paper Co., Ltd. was successfully put into production in October, 2006. After putting into operation, the system operates well, and the product quality meets the design indicators. It is used in the papermaking and filling production process of medium and high-end cultural paper, not only the quality of the paper produced. In December of the same year, Henan Xinya paper white mud refining filler calcium carbonate project undertaken by the company was put into production and successfully passed the acceptance. The practice of the project of recovering alkali from alkaline straw pulp and refining filler with white mud has proved that the technology of refining calcium carbonate with white mud can fully meet the needs of industrial production and papermaking production. Both the quality of calcium carbonate produced and the quality of paper products after filling meet or exceed the relevant national standards. The success of this technology provides a new method for the comprehensive utilization of straw pulp alkali recovery white mud, which has significant social and economic benefits

the 10000 ton project of the first phase of the white mud refined calcium carbonate project of Shandong MCC Yinhe Paper Group was completed in February, and the project is in the charge of Beijing watmar environmental protection technology company. As of December, 2007, the project has produced nearly 7000 tons of white mud light calcium carbonate (absolutely dry), more than 20000 tons of paper, reduced the landfill area by 6000 cubic meters, equivalent to an area of 20 mu of land, and achieved a direct benefit of 2million yuan

Henan Xinya Paper Group Co., Ltd. is also responsible for the white mud refined calcium carbonate project, which was completed in March and accepted in April. During this period, 10000 tons of white mud light calcium carbonate were produced, and the original filler talc powder produced in paper making has been completely replaced by white mud refined calcium carbonate

II. Introduction to technology

introduction to process flow

white mud recovery refined calcium carbonate production process flow includes optimization and transformation of the existing causticization process flow and white mud refined calcium carbonate process flow; The optimization and transformation of its mechanical performance is not inferior to the causticization process, including the addition of lime classification, green liquor purification, common sheet metal damage at the green mud in the process of transportation, green liquor filtration, removal of excess ash and other parts on the basis of the original process, as well as the optimization of causticization process conditions; The refining process of white mud refining calcium carbonate includes dealkalization, slag removal, washing and concentration regulation, pH value regulation and stability, bacteria prevention treatment, homogenization and other parts

III. technical features

select high-quality quicklime raw materials, strengthen lime classification treatment, ensure the quality of lime, and make lime use reasonably; The combined action of various chemical additives makes the purification of green liquor in a real sense; By washing and filtering the green mud, the loss of alkali is reduced; The causticized green liquor is finely filtered, and no link that may affect the quality of green liquor is missed; The ash removal process and causticization process of white mud are scientifically integrated; The impurity removal process is integrated in the causticization and refining process. After several stages of separation, the solid impurities in the white mud are removed step by step; The active alkali in white mud that is difficult to wash off is treated by chemical method with dealkalization agent, which is conducive to improving the quality of white mud and saving water; While doing a good job in pH value adjustment and stable reaction, carry out anti-corrosion and sterilization treatment on white mud calcium carbonate; In order to obtain calcium carbonate particles with good uniformity, white mud was treated with high-strength dispersion and homogenization

in a word, this technology can well produce light calcium carbonate according to the production situation of the causticization workshop, ensure the stable and optimized production of alkali recovery while producing the qualified light calcium carbonate white mud, and meet the production conditions of the paper machine when filling the paper making machine, so as to produce qualified and high-quality paper

IV. production and application of technology

product quality indicators and characteristics

Whiteness: more than 88%; Calcium carbonate content: more than 90%; Free alkali (CAO): less than 0.05%; PH value: 8 About 5; Average particle size: m; The maximum particle size is not more than 15 m; Sieve residue: 125 m test sieve is less than 0.005%, 45 m test sieve is less than 0.30%; Dust degree: no dust above 0.4m2; Complete sedimentation volume: more than 2.8/g (lotion); Concentration of finished lotion: 18% - 20%

product inspection and test table:

the particle size distribution of white mud calcium carbonate product is shown in the figure below

2. Filling effect

use 100% white mud to replace commercial calcium carbonate, and fill it on the production of medium and high-end cultural paper machines. The test results of the paper are as follows:

compared with commercial calcium carbonate filling, the paper index has the following effects:

-- the thickness of the paper is increased, and the thickness is increased by about 5% under the same ash content

-- the opacity is improved. Under the same ash content, the opacity is increased by more than 5%

-- no adverse effect on whiteness

-- fracture length, folding resistance, surface strength and other indicators are slightly improved

-- the amount of filler is reduced from 32% to about 28% now, the retention rate of filler is increased by more than 8%, and white mud calcium carbonate filler shows strong adhesion to fiber

-- reaching the same surface absorption value, the dosage of AKD is significantly increased, with an increase of about 25% - 50%

v. benefit analysis

at present, the comprehensive work of energy conservation and emission reduction formulated by the development and Reform Commission and relevant departments issued by the State Council also indicates the degree of stratification, which defines the goals, tasks and overall requirements for China to achieve energy conservation and emission reduction in 2010. The plan points out that the comprehensive utilization rate of industrial solid waste must reach more than 60% during the Eleventh Five Year Plan period. The technology of refining calcium carbonate with white mud can achieve this goal for the majority of paper and pulp enterprises, which will also provide inexhaustible development power for the extruder industry, and points out the direction of the target

white mud recovery refined filler is used in the construction of paper filling project. While introducing the new technology of white mud refined filler calcium carbonate, technological transformation is carried out in the causticization section to refine the white mud into calcium carbonate products that meet the paper filling, which not only increases the profit space of the enterprise, but also reduces the loss of alkali in the causticization production process, thus reducing the unit product cost of alkali recovery. The enterprise not only solves the problem of environmental protection, but also increases the net profit by 4million yuan/year (taking the annual output of 20000 tons of absolutely dry white mud as an example)

VI. conclusion

the alkali recovery of white mud from alkaline straw pulp adopts the new technology of refining calcium carbonate from white mud of Beijing wattmade Environmental Protection Technology Co., Ltd. to produce calcium carbonate products for paper filling, which has been proved to be feasible in practice. Its successful application has achieved the purpose of protecting the environment, reducing pollution, turning waste into treasure, and saving resources, and has good economic, environmental and social benefits. (end)

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