Method for preparing fine calcium phosphate by weak acid leaching of triple super phosphate

Abstract

This invention relates to a method for preparing fine calcium phosphate by leaching triple superphosphate with weak acid characterizing in leaching cured and loosen triple superphosphate with weak acid referring to adding little inorganic acid, such as H2SO4, HCl, HNO3 or H3PO4 aiming at increasing solubility of calcium phosphate primary in water to dissolve efficient P2O5 at the most and proportion of Mg ions entering into the product is reduced in it by adding calcium dissolvable acid to ensure quality of the product.

Description

1. Technical field [0001] The technical field of application of the invention is the production of fine phosphates. 2. Background technology [0002] The production methods of fine calcium phosphate salts (such as feed grade calcium hydrogen phosphate and toothpaste grade calcium hydrogen phosphate) are basically produced by wet process phosphoric acid or hot process phosphoric acid. The fine calcium phosphate salt produced by thermal phosphoric acid has good quality and high purity, but its production cost is relatively high. This process route is suitable for the use of phosphate with high value-added; while the phosphate produced by wet process phosphoric acid needs to remove phosphoric acid. Only by impurity purification can we produce qualified fine phosphate products, but this kind of process route is often complicated, the investment of engineering equipment is high, the floor area is large, and there are many shortcomings such as many factory operators. At present, ...

AI Technical Summary

Problems solved by technology

The fine calcium phosphate salt produced by thermal phosphoric acid has good quality and high purity, but its production cost is relatively high. This process route is suitable for the use of phosphate with high value-added; while the phosphate produced by wet process phosphoric acid needs to remove phosphoric acid. Only by impurity purification can we produce qualified fine phosphate products, but this kind of process route is often complicated, the investment of engineering equipment is high, the floor area is large, and there are many shortcomings such as many factory operators.

At present, in the process of using double superphosphate as a phosphorus source to produce fine calcium phosphate salts, the patent application number CN98115729 uses clear water to leach heavy superphosphate, and the obtained clear liquid is neutralized with soda ash to obtain a solid ——Common calcium superphosphate, add sodium salt to the liquid phase to remove fluorine, filter, and neutralize the clear liquid with lime to obtain feed grade calcium hydrogen phosphate. The disadvantage of this process is: leaching with process water, the liquid-solid ratio is too high Low (2:1), it is difficult to completely leach the effective phosphorus pentoxide in double superphosphate, and in the defluorination process, it is difficult to remove the fluorine only by adding sodium salt (according to sodium hexafluorosilicate or potassium Solubility diagram data of salt), product quality is also difficult to reach HG2636-2000 standard

And the patent that application number is 85102375 (authorization number 1011583) is to leaching common calcium superphosphate with clear water, and liquid-solid ratio is also 2: 1, and the advantage of this patent is that technique is simple and easy, and shortcoming is the effective five in common calcium superphosphate The phosphorus oxide leaching rate is not high, and a large amount of calcium sulfate hemihydrate (CaSO 4 1 / 2H 2 O), this gypsum has fine crystals and is less efficient in filtration in industrial installations

In addition, the above two patents do not provide a technical route for producing qualified products from high-magnesium double superphosphate and ordinary calcium superphosphate.

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