Water-saving and emission-reducing wet method phosphoric acid manufacture process

Abstract

The invention discloses a wet-process phosphoric acid production process used for saving water and reducing exhaust, relating to a process which produces the wet-process phosphoric acid by a dehydrate method. The process comprises the steps as follows: qualified pulp is concentrated and filtrated; part of the filtrated mineral powder is conveyed to a metering auger by a belt conveyor and subsequently added into a mixed trough; the other part of the filtrated mineral powder is stored in a mineral powder bin; the mineral powder which enters the mixed trough is reacted with return phosphoric acid of the wet-process phosphoric acid and washed water under stirring and sent to a wet-process phosphoric acid extraction reaction trough by a pump; the dilute phosphoric acid is prepared according to the traditional method; the water separated by a filter is sent to a wet grinder, and is measured and mixed with phosphate ore, and then the mixture is grinded in a grinding machine and repeatedly used. The production process has the advantages that (1) a great amount of supplemented water of ore grinding part is saved, the drained water quantity is greatly reduced; (2) the pulp storage equipment is not needed completely, the energy resource consumption and burdensome labor consumption are reduced; and (3) the production capacity of the phosphoric acid is about 16-30 percent, furthermore, compared with the original process, the change of the investment of the process is little.

Description

technical field [0001] The present invention relates to phosphoric acid, in particular to the process for producing wet-process phosphoric acid by the dihydrate method. technical background [0002] The most mature and extensive process of wet-process phosphoric acid production is the process of producing dilute phosphoric acid after reacting phosphate rock with sulfuric acid, extracting and filtering dihydrate gypsum. The production scale of a single series has reached 1000t / a100%P 2 o 5 . The sewage generated in the phosphoric acid production process is the main source of sewage discharge for phosphate fertilizer enterprises, and its sewage discharge accounts for about 50% to 80% of the total amount of phosphate fertilizer enterprises. Especially for large phosphate fertilizer enterprises that use ore pulp to produce large amounts of water, their Sewage discharge is more difficult to control. Aiming at the improvement of wet-process phosphoric acid production process, s...

AI Technical Summary

Problems solved by technology

After the ore slurry brings a large amount of water into the wet-process phosphoric acid production system, it is necessary to reduce the amount of phosphorus-containing sewage that is inevitably generated in the process and reuse it in the production system, and it is difficult to control, especially to achieve the balance of process water

This will have the following effects: first, the amount of phosphoric acid washing water is reduced, the washing is insufficient, and the water-soluble residual phosphorus of phosphogypsum increases; second, the concentration of dilute phosphoric acid is reduced, the production capacity is reduced, and the consumption of concentrated phosphoric acid steam is increased; Balance, increased sewage discharge, increased environmental risks and sewage treatment costs

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