Method for producing feed-grade wet-process purified phosphoric acid and high-purity high-whiteness semi-hydrated gypsum

Abstract

The invention discloses a method for producing feed-grade wet-process purified phosphoric acid together with high-purity high-whiteness semi-hydrated gypsum. The method includes following steps: subjecting raw phosphorite to smashing, grinding and flotation to obtain concentrate pulp, adding a metal ion inhibitor into the concentrate pulp, and filtering and separating after reaction to obtain pretreated phosphorite pulp; enabling phosphoric acid and the pretreated phosphorite pulp to be in extraction decomposition reaction, adding a compound purifying agent for defluorination and dearsenification, filtering and separating mixed pulp after reaction to obtain a filter cake I and filtrate I, adding monocalcium phosphate crystallization improver into the filtrate I for monocalcium phosphate cooling crystallization, filtering and separating to obtain crystallized monocalcium phosphate and filtrate II, enabling crystallized monocalcium phosphate and concentrated phosphoric acid to be in secondary extraction reaction, filtering and separating to obtain filtrate-the wet-process phosphoric acid, using hot water to wash the filter cake, and drying the filter cake to obtain semi-hydrated gypsum. By the method, concentration of the wet-process phosphoric acid is increased, impurity content is lowered, and the feed-grade wet-process phosphoric acid and high-purity high-whiteness semi-hydrated gypsum can be obtained.

Description

technical field [0001] The invention relates to a method for producing feed-grade wet-purified phosphoric acid and co-producing high-purity and high-whiteness hemihydrate gypsum, which belongs to the technical field of chemical production. Background technique [0002] Phosphoric acid is the basic raw material for producing various industrial and agricultural phosphorus products. At present, there are two industrial techniques for producing phosphoric acid: "thermal" process and "wet" process. [0003] Among them, the thermal phosphoric acid process refers to the use of phosphate rock as the main raw material, high-temperature reduction with coke in an electric furnace at 1300°C-1500°C to obtain elemental phosphorus, and then sublimates and escapes in a vapor state, and then burns and hydrates to produce 85% phosphorus. Thermal phosphoric acid. The thermal phosphoric acid product produced by the "thermal method" process has high purity, high concentration and less impuritie...

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Problems solved by technology

[0008] The disadvantages of the above two techniques are: (1) the wet-process phosphoric acid products produced by the two techniques are not purified or purified, and the impurities such as iron, aluminum, magnesium, and fluorine are high in content, and cannot be directly applied to Production of Feed Grade Phosphate Products

(4) The latter process converts 30-50% of the calcium in the phosphate rock into ordinary hemihydrate gypsum, and the remaining calcium is converted into high-purity and high-whiteness hemihydrate gypsum, but the impurities in the phosphate rock eventually enter the ordinary In hemihydrate gypsum, the impurity content of ordinary hemihydrate gypsum increases, the purity of gypsum decreases, and the utilization range of ordinary phosphogypsum is further reduced

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