Recovery treatment method for waste phosphoric acid

Abstract

The invention provides a recovery treatment method for waste phosphoric acid. The method comprises the following steps: pretreating waste phosphoric acid, and carrying out nanofiltration treatment toobtain a nanofiltration permeate and a nanofiltration trapped fluid; adding an alkaline substance into the nanofiltration trapped fluid to remove impurities, and carrying out solid-liquid separation to obtain a phosphate solution; and electrolyzing the phosphate solution to obtain phosphoric acid and alkali, and returning the alkali for recycling. According to the method, the waste phosphoric acidis sequentially subjected to nanofiltration, neutralization, precipitation and electrolysis operation, impurities in the waste phosphoric acid are separated, enrichment and recovery of phosphoric acid are achieved, and the recovery rate of phosphoric acid is high; the recovered phosphoric acid is high in purity and excellent in performance, and can meet the requirements of industries such as semiconductors; the method is simple to operate and relatively low in cost, and resource utilization of the waste acid solution is realized.

Description

technical field [0001] The invention belongs to the technical field of waste liquid treatment, and relates to a method for recycling waste phosphoric acid. Background technique [0002] With the rapid development of economy and society, the discharge of waste liquid is increasing day by day. Among them, waste acid is a kind of highly corrosive waste liquid. If it is discharged without effective treatment, it will inevitably cause great damage to the environment; and the current scale is rapidly The expanded electronics industry, semiconductor industry and other production processes will produce a large amount of waste acid. As a medium-strong acid, phosphoric acid is widely used in chip manufacturing and other production processes. Therefore, waste phosphoric acid is an important waste acid. Research on the recycling process is essential. [0003] CN 101602560A discloses a method for concentrating and recovering low-concentration industrial waste acid water, including: (1) ...

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Problems solved by technology

[0003] CN 101602560A discloses a method for concentrating and recovering low-concentration industrial waste acid water, including: (1) pretreatment of waste acid water, first using aeration method to separate out the difficult-to-remove substances dissolved in the waste water, and then filtering with high-efficiency fiber (2) Osmotic distillation. The pretreated waste acid water enters the osmotic distillation membrane module for osmotic distillation dehydration. (3) The removal agent is evaporated and concentrated, and the removed agent diluted in step (2) is evaporated and concentrated, and osmotic distillation will be used after saturation or supersaturation; (4) Concentrated acid water Purification treatment, the concentrated acid water is filtered with nanofiltration membrane modules to remove impurities such as iron ions; the application of this method has restrictions on the type and concentration of acids in waste acid water, and it is mainly suitable for hydrochloric acid or sulfuric acid, and for phosphoric acid. Poor sex

[0004] CN 205699506U discloses an electronic-grade phosphoric acid recovery and treatment device for electronic waste acid liquid, including an evaporation concentration unit, a dilute acid recovery unit, a negative pressure vacuum unit, and a cooling water circulation unit. The evaporation concentration unit includes a preheater, an evaporator and a separation The dilute acid recovery unit includes a condenser, a non-condensable gas condenser and a dilute acid tank, the negative pressure vacuum unit includes a gas-liquid separation tank and a vacuum unit, and the cooling water circulation unit includes a cooling tower and a cooling water pump. The concentration method realizes the concentration treatment of electronic grade phosphoric acid, and the treatment process is completed under negative pressure, but the device is mainly used for the separation of volatile acids such as nitric acid and acetic acid in phosphoric acid, and does not involve the separation of other types of impurities. The resulting phosphoric acid still cannot be used directly

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