Method for producing high-quality polyphosphoric acid

Abstract

The invention belongs to the technical field of hot-process phosphoric acid production in the inorganic chemical industry and relates to a method for producing a high-quality polyphosphoric acid. The method is capable of further improving the advancement of the polyphosphoric acid production process and the quality of the obtained product, and as a result, the concentration of the obtained polyphosphoric acid product, converted into the content of orthophosphoric acid, ranges from 100% to 116%, and the content of arsenic in impurities contained in the obtained polyphosphoric acid product is low to the concentration range from 0.1ppm to 1.9ppm; in implementation, the production method comprises the major process steps of burning yellow phosphorus with air in a combustion furnace to generate phosphorus pentoxide flue gas, enabling the phosphorus pentoxide flue gas to enter a hydration-polymerization tower and react to generate the polyphosphoric acid, and carrying out arsenic removal and filtering by virtue of hydrogen sulfide gas, and then carrying out treatments such as color modulation on the polyphosphoric acid obtained through filtering to obtain the finished product.

Description

technical field [0001] The invention belongs to the technical field of thermal phosphoric acid production in the inorganic chemical industry, and relates to a production method of high-quality polyphosphoric acid. Background technique [0002] Polyphosphoric acid is a product with high added value among phosphorus chemical products. It is a relatively new type of chemical raw material. Its main components are orthophosphoric acid, tripolyphosphoric acid, pyrophosphoric acid, tetrapolyphosphoric acid and high polyphosphoric acid. Molecular formula: H (n+2) P n o (3n+1) ; [0003] Structural formula: [0004] Typical product molecular formula: H 6 P 4 o 13 . The phosphoric acid content of polyphosphoric acid is generally 105-115%H 3 PO 4 , including P 2 o 5 Greater than 76%. Polyphosphoric acid has a low viscosity and freezing point, so it is not easy to crystallize in winter, and it remains liquid when stored at low temperature, and is less corrosive. It can be...

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Problems solved by technology

[0018] In addition, the "polyphosphoric acid dearsenic process" published by the patent CN201010207444.4 points out that the dearsenic is removed by adding sulfide to the (poly)phosphoric acid solution, but the patent does not report the concentration of polyphosphoric acid capable of dearsenic, There is no report on the production of polyphosphoric acid, let alone how low the arsenic content in the polyphosphoric acid product after arsenic removal can reach

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