Preparation method of phosphorous acid

Abstract

The invention relates to a preparation method of phosphorous acid. The invention relates to the inorganic acid preparation technique, namely to the phosphorous acid manufacturing technique, and can beused for further processing of phosphorus-contained residue obtained as an accessory substances during electric heating production of phosphorus. In order to reduce the time of soda treatment processof the phosphorus-contained residue, improve the phosphorous acid productivity and quality, and reduce the conversion of phosphorus into phosphine, the preparation method of phosphorous acid from phosphorus-contained raw material includes: using sodium hydrate solution to perform soda treatment; separating the aqueous alkali and precipitation; oxidizing the dissolved sodium hypophosphite into phosphate-ion, converting the phosphate-ion into the form of phosphorous acid, and proposing to take the phosphorus-contained residue as original phosphorus-contained raw material. The original residue is washed by water beforehand, processed by non-ionic emulsifier solution, the sodium hypophosphite is oxidized by sodium hydrate in the presence of barium hydroxide, the barium contained deposition isseparated from the solution, and the barium sulfate deposition and phosphorous acid solution are obtained by using sulfuric acid solution to process.

Description

technical field [0001] The present invention relates to a process for the preparation of mineral acids, ie phosphorous acid, which can be used for the treatment of phosphorus-containing residues obtained as by-products in the electrothermal production of phosphorus. Background technique [0002] It is known to oxidize elemental phosphorus to phosphorus trioxide, which is then dissolved in cold water to prepare phosphorous acid. The phosphorous acid that obtains according to this method mixes many phosphoric acids, and its purification is a very complicated work (French patent № 2125587, C01D25 / 16, 1972). [0003] Phosphorous acid can be prepared by oxidizing phosphorus with chlorine under the water layer, or by mixing concentrated hydrochloric acid with 5-15% in PCl 3 PCl in an inert organic solvent 3 Solution interactions are prepared. The defect of this method is complex equipment structure, poor working conditions, phosphorous acid mixed with chlorine, organic compound...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that phosphorus is lost due to the generation of phosphine when the yellow phosphorus is hydrolyzed, so the phosphorus yield in the final product is low (no more than 50-55%), and the process is multi-stage and efficient.

The use of expensive catalysts complicates the process and helps to oxidize some of the phosphite-ions to phosphate-ions, contaminating the phosphorous acid

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