Method for preparing low alkalinity calcium carbonate

Abstract

The invention relates to a method for preparing low alkalinity calcium carbonate, which comprises the following steps of: 1, filling washed lime kiln fume containing carbon dioxide into Ca(OH)2 suspension to carry out carbonization; 2, aging; 3, carrying out secondary deep over-carbonization on calcium carbonate slurry; 4, dehydrating by a centrifugal machine and then drying; and 5, carrying out depolymerization on calcium carbonate aggregates, simultaneously filling hot air to carry out secondary deep drying on depolymerized calcium carbonate particles, dropwise adding inorganic condensation acid to carry out surface treatment on the calcium carbonate particles and finally separating calcium carbonate from the hot air, sieving to remove coarse particles to obtain the finished product of the low alkalinity calcium carbonate with a pH value of lower than 8.0. The problems of excessively high alkalinity and low acid nonresistance of calcium carbonate products which are currently produced in China are solved. The application of the national calcium carbonate is expanded, so that the calcium carbonate can still be used in a product formula system sensitive for the alkalinity and the effects of filling cost reduction and modification and upgrading are achieved. The method has important significance for promoting the development of both the national calcium carbonate production industry and the material manufacturing industry in which the calcium carbonate is used as packing.

Description

technical field [0001] The invention relates to a preparation method of calcium carbonate, in particular to a preparation method of low-alkalinity calcium carbonate. Background technique [0002] Calcium carbonate is a widely used inorganic salt industrial product. It can be used as a filling and modification material in plastics, rubber, paint, adhesives, papermaking, food processing, pharmaceuticals and other industries. It is closely related to people's daily life. Relationship. [0003] At present, the domestic general calcium carbonate industrial preparation method is as follows: [0004] To a certain concentration of Ca(OH) at a certain temperature 2 The suspension is passed through the washed lime kiln flue gas containing carbon dioxide for carbonization, so that Ca(OH) 2 The ph value of the suspension drops continuously. After the ph value reaches 7.0, the carbonization reaches the end, and the calcium carbonate slurry is obtained, and then the prepared calcium ca...

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Problems solved by technology

[0009] The technical problem to be solved by this invention is to overcome the deficiencies in the above-mentioned current calcium carbonate industrial preparation technology that is current in my country, and to provide a calcium carbonate product that can reduce the alkalinity of the calcium carbonate product to below the pH value of 8.0 and has certain acid resistance. Preparation method, i.e. the preparation method of low-alkalinity calcium carbonate, to solve the problem of high alkalinity and acid resistance of calcium carbonate products produced in my country at present, to expand the use of domestic calcium carbonate products, so that it can be used in product formulas sensitive to alkalinity It can also be used in the system to achieve the effect of filling cost reduction and modification

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