A wet-process phosphoric acid concentration method and device

Abstract

The invention relates to the technical field of wet method phosphorus acid concentration and especially provides a concentration method and a concentration apparatus for wet method phosphorus acid. In the apparatus, a concentrated acid precipitation unit is connected to a secondary acid pump; the secondary acid pump is connected to a concentration mechanism; and the concentration mechanism is connected to a finish product acid precipitation unit. With limitation on concentration, specific gravity and solid content of the wet method phosphorus acid fed from a material inlet, and limitation on flow rate and processing time during the treatment process, the method has better wet method phosphorus acid concentration effect than a conventional method. When processing load is 750000 ton, solid content is reduced by 55675.85 ton, and meanwhile, 59140.87 ton of clear acid is avoided from being brought away by solid, so that the yield of concentrated clear acid is increased by about 8%. The method and the apparatus reduce the loss rate of the clear acid and reduce cost.

Description

technical field [0001] The invention relates to the technical field of wet-process phosphoric acid concentration, in particular to a wet-process phosphoric acid concentration method and device. Background technique [0002] The production process of wet-process phosphoric acid in the prior art is to pump the dilute acid from the slurry extraction production process to the graphite heat exchanger by metering and pumping, using steam as the heat source, phosphoric acid in the tube side, steam in the shell side, and steam through the column The tubular graphite heat exchanger performs heat exchange, provides kinetic energy for the axial flow pump, and controls the steam temperature, pressure, steam flow, dilute acid flow, acid output, liquid level and flash vacuum at the inlet of the graphite heat exchanger, so that the dilute acid The water in the solution is lost, and concentrated into a product with an acid concentration of 44.5%, a phosphorus pentoxide content of 44.5%, a s...

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Problems solved by technology

[0003] In this process, since the viscosity of phosphoric acid increases with the increase of concentration and temperature, some impurities will reach a supersaturated state due to water evaporation during the concentration process and crystallize out, resulting in the graphite heat exchanger being used for 10 days. After left or right, the scaling and thickening rate of the inner wall is relatively large, resulting in a decrease in heat transfer capacity, shortening the normal operation time of the concentration device, and even being forced to shut down for chemical immersion cleaning, mechanical high-pressure dredging, and manual cleaning, which makes the treatment of wet-process phosphoric acid The labor intensity of concentration treatment is high, the cost is high, and the treatment efficiency is low; and it will also cause part of the structure of the graphite heat exchanger to be damaged during the cleaning process, which will shorten the service life of the graphite heat exchange and increase the efficiency. Increased the concentration cost of wet-process phosphoric acid; in addition, the solid content in the concentrated clear acid after concentration treatment is relatively high, and the amount of clear acid taken away by solid waste residue is large, resulting in a small amount of concentrated clear acid obtained , poor quality

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