A method for comprehensive utilization of phosphorous and fluorine-containing wastewater

Abstract

The invention relates to the field of wastewater comprehensive utilization, and particularly relates to a comprehensive utilization method of wastewater containing phosphorus and fluorine. The comprehensive utilization method comprises the following steps: carrying out twice neutralization on the wastewater containing phosphorus and fluorine, and controlling the final pH value after each time of neutralization; separating calcium fluoride from wastewater according to the solubility product of calcium fluoride and calcium orthophosphate, so as to enable the main ingredients of wastewater to be calcium orthophosphate and silica gel; separating silica gel by centrifugal separation to obtain a waste liquid containing phosphorus; carrying out secondary neutralization on the waste liquid containing phosphorus to enable the pH value to be 4-7; after generating calcium hydrophosphate, carrying out cooling crystallization treatment; separating calcium hydrophosphate to obtain a clear liquid, so as to realize treatment on wastewater containing phosphorus and fluorine. By adopting the comprehensive utilization method, maximal reutilization of the phosphorus fluorine resource is realized, the by-product silica gel is generated, the product additional value is increased, and the cost of treatment on wastewater containing phosphorus and fluorine is reduced.

Description

Technical field [0001] The invention relates to the technical field of comprehensive utilization of waste water, in particular to a comprehensive utilization method of phosphorus and fluorine-containing waste water. Background technique [0002] Phosphorus-containing fluorine wastewater is an inevitable acidic wastewater produced by phosphoric acid production enterprises; the discharge of this wastewater in the environment will cause serious environmental pollution. For this reason, acid-base neutralization methods are usually used in the prior art to remove phosphorus and fluorine. After the wastewater is neutralized to neutral treatment, solid-liquid separation technology is combined to filter the solid waste residue formed in it, and then the treated clear liquid is discharged. In phosphoric acid production enterprises, phosphate rock and inorganic Acid is produced by reaction, and phosphate rock contains a variety of impurity elements, such as fluorine, silicon, calcium, etc....

AI Technical Summary

Problems solved by technology

[0002] Phosphorous and fluorine-containing wastewater is the unavoidable acidic wastewater produced by phosphoric acid production enterprises; the discharge of this wastewater in the environment will cause serious pollution to the environment. After the waste water is neutralized to neutral treatment, solid-liquid separation technology is combined, and the solid waste residue formed in it is filtered, and the treated clear liquid is discharged; in phosphoric acid production enterprises, phosphate rock and inorganic acid, and phosphate rock contains a variety of impurity elements, such as fluorine, silicon, calcium, etc., so in the production process, it will not only lead to a large amount of waste residue, but also lead to a large amount of waste In the waste liquid, due to the high impurity content and low concentration of part of the fluorosilicic acid, it is difficult to be separated from the mixture with part of the low-concentration phosphoric acid, and then forms phosphorus and fluorine-containing waste water that coexists with phosphorus and fluorine.

[0003] In the above-mentioned prior art, for the treatment method of wastewater containing phosphorus and fluorine, although it can treat the pollution degree of the wastewater when it is discharged to a certain extent, in order to meet the discharge standard, the treatment still cannot reach the ideal standard, and at the same time Also caused the higher processing cost and caused the waste of phosphorus and fluorine

[0004] Of course, there are currently some researchers who recycle the phosphorus and fluorine in the phosphorus and fluorine waste residue through the extraction method, and extract by adding sulfuric acid to reduce the content of calcium ions in it, and increase the concentration of phosphate radicals in it, and then further Concentrate phosphate radicals to obtain phosphate products, and discharge fluorine in the form of gas during the phosphate radical concentration process, and absorb and utilize the exhausted gas, thereby achieving the separation of phosphorus and fluorine-containing waste residue or phosphorus and fluorine resources in waste liquid However, this method consumes a lot of energy and is not ideal for the recovery and utilization of fluorine resources, which will cause some fluorine gases to be difficult to be absorbed and utilized due to high temperature, and will be discharged into the environment, causing secondary pollution of the atmosphere