Method for using phosphoric oxide to concentrate diluted phosphoric acid to prepare polyphosphoric acid

Abstract

A method for using phosphoric oxide to concentrate diluted phosphoric acid to prepare polyphosphoric acid, including following steps: mixing yellow phosphorus and air with the proportion of 1kg yellow phosphorus to 6.3-6.6 m3, burning, absorbing the obtained P2O5 by diluted acid; applying the obtained phosphoric acid into a phosphoric acid groove; then using acid pump to send into a condenser to remove the heat; then sending the phosphoric acid into a hydration tower to circularly spray and absorb P2O5 to increase the concentrated phosphoric acid; cycling without stop to obtain the phosphoricacid having 82%-84% P2O5. The recovery coefficient of phosphorus is more than 98%. The obtained product reaches the standard of the food-level phosphoric acid. This invention may greatly reduce the cost of package and distribution of the phosphoric acid production enterprise via using the wet-method phosphoric acid or hot-method phosphoric acid of the concentrated content of the phosphoric acid anhydride of less than 100% obtained by yellow phosphorus burning. This invention does not need to consume the extra energy, and can fully use the burning heat and the hydration heat of the yellow phosphorus; the generated steam can be recycled. So this invention has the advantages of saving energy and greatly reducing the production cost of the polyphosphoric acid, with remarkable social and economic benefits.

Description

technical field

[0001] The present invention relates to phosphorus and its oxides, and also to phosphoric acid, and more specifically, to a method for producing polyphosphoric acid. Background technique

[0002] Phosphoric acid is a basic chemical raw material. The phosphorus sold in the market mainly has two specifications of 85% and 75%.

[0003] There are many ways to produce phosphoric acid, mainly including wet process phosphoric acid and thermal process phosphoric acid. To obtain high-concentration phosphoric acid from wet-process phosphoric acid, it must be concentrated to remove the water. There are many ways to concentrate phosphoric acid, the main ones are: (1) direct heat transfer by external combustion (such as wet wall evaporation); (2) direct heat transfer by immersion combustion (such as Nordank immersion combustion concentration evaporation); (3) indirect heat transfer Thermal evaporation (eg Swenson forced circulation vacuum evaporator). These several me...

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