Abstract
The introduction of fillers into various materials improves its technological, physical and mechanical properties, and leads to a decrease in cost. The main areas of application of natural and synthetic calcium carbonate as highly dispersed fillers are: the construction industry, the production of Portland cement, mineral fertilizers, glass, paper, polymer composite materials, paints and varnishes, and rubbers. A promising direction at present is the use of production by-products as fillers, for example, conversion calcium carbonate - a waste product from the production of a complex mineral fertilizer - nitroammophoska. However, its use in the above areas is limited by the content of water-soluble nitrogen-containing impurities, impurities of heavy metals, strontium carbonate, phosphates, etc. The analysis of scientific, technical and patent literature on methods of purification of conversion calcium carbonate has been carried out. These methods are based on the extraction of impurities from the initial product of calcium carbonate production - a melt of calcium nitrate tetrahydrate by precipitation with various reagents, followed by the isolation of an insoluble precipitate (impurities) and processing of the purified melt into calcium carbonate and nitroammofoska. A method is proposed for the extraction of acid-tonic-soluble iron-containing impurities from the initial calcium nitrate melt in order to obtain a cleaner by-product - conversion calcium carbonate, which will expand the scope of its application. An effective method is to dilute the initial calcium nitrate melt with a 60% solution of ammonium nitrate to a calcium content of 12-13%, followed by the isolation of an acid-insoluble precipitate in a vacuum filter, conversion of the purified calcium nitrate solution with ammonium carbonate and separation of the resulting suspension in a drum filter. The described method can reduce the amount of iron-containing impurities by more than 50%.
Highlights
Химическая промышленность: получение кальцинированной соды, кормовых фосфатов и кальцийсодержащих удобрений, синтетических моющих средств, карбида кальция, хлорной извести; Для цитирования
A promising direction at present is the use of production by-products as fillers, for example, conversion calcium carbonate - a waste product from the production of a complex mineral fertilizer - nitroammophoska
The analysis of scientific, technical and patent literature on methods of purification of conversion calcium carbonate has been carried out. These methods are based on the extraction of impurities from the initial product of calcium carbonate production - a melt of calcium nitrate tetrahydrate by precipitation with various reagents, followed by the isolation of an insoluble precipitate and processing of the purified melt into calcium carbonate and nitroammofoska
Summary
Химическая промышленность: получение кальцинированной соды, кормовых фосфатов и кальцийсодержащих удобрений (преципитат, известково-аммиачной селитры и др.), синтетических моющих средств, карбида кальция, хлорной извести; Для цитирования. Дисперсный наполнитель на основе Natarova E.S., Nehcesova Yu.M. Dispersed filler based on synthetic синтетического карбоната кальция – требования к качеству calcium carbonate – requirements for applications quality. В этом случае степень очистки плава нитрата кальция от фтора составляет 60–98,5%, фосфора – 60–99,5%, железа – 85–99,9%. При проведении частичной конверсии плава нитрата кальция происходит совместное осаждение карбоната кальция с выделением фтора, фосфора, железа и других примесей [11].
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