Method for bleaching high-concentration kaolin pulp

Abstract

The invention relates to a method for bleaching high-concentration kaolin pulp. The kaolin pulp concentration is 25%-30%. The method comprises the following steps: adding an alkaline agent to water, mixing and adding rongalite to prepare rongalite aqueous solution, wherein, the weight ratio of sodium hydroxide to sodium carbonate in the alkaline agent is 0.33-0.47:10, the weight ratio of the rongalite to the alkaline agents is 100:10.3-10.5, rongalite volume concentration of the rongalite aqueous solution is 10-15% and the pH value of the rongalite aqueous solution is 7.0-8.0; delivering the rongalite aqueous solution and the high-concentration kaolin pulp to a conduit by a pump for mixing, and delivering the mixture to a pulp storage tank, wherein, the added amount of the rongalite aqueous solution is 1.4-2.3% of that of the high-concentration kaolin pulp; and keeping standing and bleaching for 15-20 hours, and adjusting the pH value of the pulp to 2.5-3.0 after bleaching. The method has the advantages of reasonable technical proposal, easy control of operation, stable process, and the bleached high-concentration pulp is beneficial to subsequent filter pressing dehydration processing, which improves the production capacity, reduces the energy consumption and medicament consumption, lowers the production cost and stabilizes quality of kaolin products.

Description

technical field [0001] The invention relates to a chemical bleaching method in the production of kaolin products, in particular to a bleaching method of high-concentration kaolin pulp. Background technique [0002] Kaolin is mainly used in ceramic industry, coatings, refractory materials, papermaking, paint, rubber, high-grade porcelain, wire and cable, industrial plastics, chemical industry fillers and inks, food, cosmetics, medicines, etc. There are three main types of kaolin resources in my country. One is the high-temperature thermal gap filling ore-forming kaolin represented by Suzhou kaolin. Most of this kaolin has a tubular and columnar crystal structure, and a few are flaky crystal structures. Classification after crushing is suitable for processing into products for petrochemical catalysts. The second is coal-measure kaolin, whose crystal structure is needle-like, flake-like, columnar, and tubular. Because it is polluted by coal during the mineralization process, it...

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Problems solved by technology

The second is coal-measure kaolin, whose crystal structure is needle-like, flake-like, columnar, and tubular. Because it is polluted by coal during the mineralization process, it must be calcined and further processed. After processing, it becomes another mineral material. It is mostly used in rubber fillers and high-grade paint coatings, and a few are used in paper-making coatings. Its processing cost is higher than that of sandy kaolin, and its popularization and application are limited.

[0003]The sandy kaolin in Maoming is mainly mined by hydraulic flushing method. Due to the low concentration of pulp (pulp concentration is generally 8-15%), the bleaching method in production mostly adopts direct Add sulfuric acid and sodium hydrosulfite to carry out stirring and bleaching. Due to the low concentration of kaolin pulp, sodium hydrosulfite is easily hydrolyzed and self-reacted when it encounters water under acidic conditions. It is not conducive to the subsequent processing of the filter press dehydration process; for the bleaching of high-concentration kaolin pulp, due to its high viscosity and difficult stirring, it is difficult to evenly distribute the sodium hydrosulfite for bleaching. If the sodium hydrosulfite is dissolved in water, it is easy to Hydrolysis occurs and self-reaction occurs, its properties are extremely unstable, and the bleaching effect decreases rapidly with the passage of time. After 30 minutes, there is no bleaching effect on the pulp, and the consumption of hydrosulfite is large

[0004] patent CN89107952.1 provides a kind of process with complexation method to remove iron from kaolin bleaching, preferably complexing agent, network agent, reducing agent and dispersant and their Ratio of ingredients to achieve iron removal and bleaching, complex formula

Patent application CN200410052171.5 provides a kind of production method of superfine kaolin, the pulp concentration of chemical bleaching is low (6~12%), add sulfuric acid, hydrosulfite, and alkaline agent to bleach, patent application CN200710053033.2 provides a kind of high viscosity The production process of concentrated kaolin, patent application CN200710053034.7 provides a production process of kaolin for papermaking coating, all of which adopt hydromechanical method to mine kaolin ore and make kaolin slurry. The main technology is not bleaching, but traditional chemical bleaching method, there are the same disadvantages of the above-mentioned technology