Method for preparing calcium hypophosphite

Abstract

The invention relates to a method for preparing calcium hypophosphite. According to the technical scheme, the method comprises the following steps: continuously adding a 50-80wt% sodium hypophosphite solution and a 60-75wt% calcium nitrate solution into a reaction crystallizer, controlling the average retaining time of the materials in the continuous reaction crystallizer to be 1-5 hours, continuously discharging a product mother liquid I from the bottom of the crystallizer, aging the product mother liquid I in an aging device for 0-3 hours, then continuously discharging from the bottom of the aging device, performing centrifugal separation, washing and drying so as to obtain calcium hypophosphite crystals of which the purity is greater than 99.0% and a crystal mother liquid II, finally evaporating and crystallizing the crystal mother liquid II so as to obtain a crude sodium nitrate product and a crystal mother liquid III, and feeding the crystal mother liquid III back to the continuous reaction crystallizer for circulation. By adopting a continuous reaction crystallization process, the method can avoid the generation of waste liquid, has the advantages of simple process, gentle operation condition, low energy consumption, stable product quality and the like and can be put into industrialization easily.

Description

technical field [0001] The invention belongs to the technical field of preparation of fine chemicals, and in particular relates to a method for preparing calcium hypophosphite. Background technique [0002] Calcium hypophosphite (Ca(H 2 PO 2 ) 2 ), commonly known as calcium hypophosphite. Calcium hypophosphite is white crystalline powder, soluble in water (normal temperature, 16.7g / 100g H 2 O), but insoluble in ethanol. Calcium hypophosphite can not only be used as flame retardant, electroless nickel plating, food additive and animal nutrition agent, etc., but also can be used in the manufacture of pharmaceuticals, antioxidants, and analytical reagents. For example: Scott (Scott brand) shark liver oil nutritional supplements contain calcium hypophosphite 414mg / 15ml. [0003] The stirring reaction between white phosphorus and milk of lime can produce calcium hypophosphite and toxic phosphine at 98°C. After the reaction is completed, filter to remove unreacted substance...

AI Technical Summary

Problems solved by technology

Although this process effectively avoids the generation of flammable, explosive and highly toxic phosphine gas in the production process, hypophosphorous acid itself is corrosive and irritating, and hypophosphorous acid vapor is very harmful to operators and the environment. Due to the low solubility and slow dissolution rate of lime in water, the large amount of water inevitably introduced in this process will increase the load and energy consumption of the subsequent evaporation and concentration process, thereby increasing production costs