CN-121990712-A - System and method for cooperatively treating mine acidic wastewater based on multistage modified phosphogypsum

Abstract

The invention relates to the technical field of industrial pollutant cooperative treatment, in particular to a system and a method for cooperatively treating mine acid wastewater based on multistage modified phosphogypsum. The system comprises a modified phosphogypsum preparation unit, a wastewater treatment unit and a resource recovery unit, wherein the phosphogypsum is converted into a high-activity material through purification, alkali modification and activation treatment, and the phosphogypsum is used for step purification and resource recovery of wastewater. The invention also provides a method for treating wastewater based on the system, which comprises the steps of adding the modified material proportionally, regulating and controlling pH, and sequentially carrying out neutralization precipitation, deep precipitation, sulfate radical crystallization and residue solidification, thereby realizing the efficient purification of the acid wastewater and the recycling of byproducts. The invention uses waste to treat waste, solves the problems of large sludge amount, difficult sulfate radical removal and phosphogypsum piling pollution in the traditional treatment technology, improves the waste water treatment efficiency and the phosphogypsum utilization rate, has less secondary pollution and high resource recovery rate, and has environmental and economic benefits.

Inventors

• TAN XIANGQIAN
• ZHANG JUNWEI
• LIU SHUN
• WANG SHIJIE
• YAO ZEYI
• JIANG DAYUAN
• KOU LEI
• Dai Xuke
• HUANG LIYUE
• YUAN MENG
• HUANG JIAN
• HE FUTIAN
• WEN WEN

Assignees

• 湖北省地质局第七地质大队

Dates

Publication Date

20260508

Application Date

20260204

Claims (10)

1. 1. A system for cooperatively treating mine acid wastewater based on multistage modified phosphogypsum is characterized by comprising a modified phosphogypsum preparation unit, a wastewater treatment unit and a resource recovery unit; the modified phosphogypsum preparation unit comprises a purification module, a modification module and an activation module which are sequentially arranged, and the phosphogypsum is subjected to the preparation unit to obtain multistage modified phosphogypsum; the wastewater treatment unit is connected with the modified phosphogypsum preparation unit and is used for receiving the multistage modified phosphogypsum and treating mine acid wastewater, and comprises a neutralization precipitation module, a deep precipitation module and a sulfate treatment module which are sequentially arranged; The resource recovery unit is used for receiving and treating the solid residue and/or the liquid raffinate generated by the wastewater treatment unit.
2. 2. The system of claim 1, wherein the purification module is configured to perform a low temperature calcination and dilute acid washing treatment on phosphogypsum.
3. 3. The system of claim 1, wherein the modification module is configured to mix the purified phosphogypsum with an alkaline modifier selected from one or more of calcium hydroxide, calcium oxide, or magnesium oxide.
4. 4. The system of claim 1, wherein the activation module is configured to load an activator selected from one or more of citric acid, tartaric acid, or sodium dodecyl sulfate onto the modified phosphogypsum surface by in situ growth or deposition.
5. 5. A method for treating acidic mine wastewater based on the system of any one of claims 1 to 4, comprising the steps of: s1, sequentially drying, crushing, calcining at low temperature and washing with dilute acid to obtain purified phosphogypsum in the modified phosphogypsum preparation unit, mixing and modifying the purified phosphogypsum with an alkaline modifier, and loading an activating agent in an in-situ growth or deposition mode to obtain a multi-stage modified phosphogypsum material; s2, adding the multistage modified phosphogypsum material into the neutralization precipitation module, carrying out neutralization reaction with mine acid wastewater, and carrying out solid-liquid separation after the pH reaches a first preset value to obtain a first mixed solution and a first solid residue; s3, transferring the first mixed solution into the deep precipitation module, adding a precipitator, adjusting the pH value to a second preset value, and performing solid-liquid separation after reaction to obtain a second mixed solution and a second solid residue; s4, transferring the second mixed solution into the sulfate treatment module, adding a sulfate precipitant, evaporating, concentrating, cooling, crystallizing and separating to obtain solid sulfate; S5, mixing the first solid residue and the second solid residue in the resource recovery unit, and performing compression molding to prepare the solidified body material for mine backfilling.
6. 6. The method of claim 5, wherein the low temperature calcination is at 160-260 ℃.
7. 7. The method of claim 5, wherein the multistage modified phosphogypsum is added in a molar ratio of effective alkalinity provided by phosphogypsum to initial acidity of the wastewater, and the molar ratio of the effective alkalinity to the initial acidity of the wastewater is 1-1.5:1.
8. 8. The method according to claim 5, wherein the precipitant is sodium sulfide or soluble phosphate, and the adding amount of the precipitant is 5% -10% of the adding mass of the multistage modified phosphogypsum material.
9. 9. The method of claim 5, wherein the first predetermined pH is 3.5-4.5 and the second predetermined pH is 6.0-7.0.
10. 10. The method of claim 5, wherein the sulfate precipitant comprises sodium chloride, sodium sulfate, ammonium chloride, or ammonium sulfate.

Description

System and method for cooperatively treating mine acidic wastewater based on multistage modified phosphogypsum Technical Field The invention relates to the technical field of industrial pollutant cooperative treatment, in particular to a system and a method for cooperatively treating mine acid wastewater based on multistage modified phosphogypsum. Background The mine acidic wastewater (ACID MINE DRAINAGE, AMD) is a polluted water body which is strong in acidity, high in sulfate and rich in various heavy metal ions (such as Fe 2+、Mn2+、Cu2+、Zn2+、Cd2+) and is generated in the mining process of the mine. The long-term discharge of the ecological agent can seriously destroy surrounding water, soil and ecosystem, and can endanger human health through a food chain. At present, the treatment methods for AMD mainly comprise a neutralization precipitation method (such as lime, sodium hydroxide and the like), a vulcanization precipitation method, a biological method, an adsorption method and the like. Among them, the lime neutralization method is widely used because of its simple operation and relatively low cost. However, the method has the remarkable defects that a large amount of sludge containing heavy metals is generated after the AMD is treated by the method, the sludge is difficult to dehydrate and has poor stability, secondary environmental risks exist, and the cost for treating the sludge is high. Secondly, precipitates such as gypsum and the like possibly generated in the neutralization process wrap unreacted lime particles, so that the utilization rate of the medicament is reduced. Thirdly, the lime neutralization method can only carry out pH adjustment and heavy metal precipitation, has limited capability of removing sulfate ions with high concentration in wastewater, and is easy to cause out-of-standard sulfate and cause pollution. Phosphogypsum is a large amount of industrial solid waste discharged in the wet-process phosphoric acid production process, the main component of phosphogypsum is calcium sulfate dihydrate, the global stocking amount is huge, the phosphogypsum occupies land after long-term stocking, and the soluble phosphorus, fluorine, trace heavy metal and other impurities contained in phosphogypsum also have the environmental leaching risk. How to realize the safe and high-value utilization of phosphogypsum is a long-standing difficult problem. Phosphogypsum itself contains a calcium source and is weak acid, and can be theoretically used for neutralizing acidic wastewater, but the original phosphogypsum has the defects of more impurities, low reaction activity and poor efficiency, and can possibly introduce new pollutants, so that the direct application has technical and environmental risks. Therefore, the development of a synergistic treatment technology which can simultaneously consume phosphogypsum waste, efficiently and deeply treat mine acid wastewater and realize byproduct recycling has important significance for reducing mine environment treatment cost and promoting industrial solid waste recycling. Disclosure of Invention The invention aims to overcome the environmental pressure and technical bottlenecks caused by the fact that a large amount of dangerous waste sludge is generated, the operation cost is high, sulfate radical is difficult to remove and phosphogypsum is piled up in a large amount in the existing mine acid wastewater treatment method, and provides a system and a method for treating mine acid wastewater by utilizing waste to treat the waste, efficiently and deeply treat the waste and realize resource recovery based on multistage modified phosphogypsum. In order to achieve the above purpose, the present invention adopts the following technical scheme: In a first aspect, the invention provides a system for cooperatively treating mine acidic wastewater based on multistage modified phosphogypsum. A system for cooperatively treating mine acid wastewater based on multistage modified phosphogypsum comprises a modified phosphogypsum preparation unit, a wastewater treatment unit and a resource recovery unit; the modified phosphogypsum preparation unit comprises a purification module, a modification module and an activation module which are sequentially arranged, and the phosphogypsum is subjected to the preparation unit to obtain multistage modified phosphogypsum; the wastewater treatment unit is connected with the modified phosphogypsum preparation unit and is used for receiving the multistage modified phosphogypsum and treating mine acid wastewater, and comprises a neutralization precipitation module, a deep precipitation module and a sulfate treatment module which are sequentially arranged; The resource recovery unit is used for receiving and treating the solid residue and/or the liquid raffinate generated by the wastewater treatment unit. Further, the purification module is configured to perform a low temperature calcination and dilute acid wash treatment on phosphogypsum. In