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A method for removing fluoride ions in bastnaesite rare earth smelting wastewater

A fluoride ion and waste water technology, applied in the fields of metallurgical waste water treatment, chemical instruments and methods, water pollutants, etc., can solve the problems of limited defluorination effect, difficult disposal of hazardous waste, and high cost of waste water treatment, reducing waste water treatment investment, The effect of reducing the cost of wastewater treatment and the reduction of dosage

Active Publication Date: 2015-09-23
NANJING GW ENVIRONMENT ENG
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

[0004] At present, lime or calcium carbide slag is mainly used to remove fluoride from alkaline-to-alkali wastewater. The fluoride removal effect is limited, and the fluoride ion removal rate is about 90%. It needs to be combined with the phosphate precipitation process for deep fluoride removal. However, fluoride colloids are easily produced during production, and it takes Add flocculants, but generate a lot of solid waste, resulting in increased wastewater treatment costs
And while using lime to remove fluoride, the radioactive elements in the wastewater form hydroxides and precipitate into the sludge. After the sludge is dehydrated, the waste residue contains radioactive elements and forms hazardous waste.
Enterprises face the dilemma of high wastewater treatment costs and difficult disposal of hazardous waste

Method used

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  • A method for removing fluoride ions in bastnaesite rare earth smelting wastewater

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Such as figure 1 As shown, the alkali conversion wastewater is adjusted to a pH value of 6-9 by adding concentrated hydrochloric acid, and the first-grade defluoridation agent calcium chloride is added according to the molar concentration ratio of calcium ions and fluoride ions of 3:4-1:1, and stirred. The first-stage defluorination reaction is fully carried out, and the mixed solution is added with flocculant polyaluminum chloride and coagulant polyacrylamide for first-stage sedimentation, and the sediment is dehydrated through the first-stage filter press, and the first-stage filter press filtrate is merged into the effluent of the first-stage sedimentation Perform secondary defluorination, and recover calcium fluoride from the mud cake produced by primary pressure filtration.

[0025] Add secondary fluoride removal agent rare earth carbonate or rare earth chloride to the effluent of the primary settlement, add the secondary fluoride removal agent according to the mol...

Embodiment 2

[0027] Alkali-to-alkali wastewater: Alkali-to-alkali wastewater produced during the alkali-transfer process of a bastnaesite rare earth smelter has a pH value of 12.8, a fluoride ion concentration of 501mg / L, and a discharge volume of 10m 3 / h.

[0028] Add concentrated hydrochloric acid to the alkali-transformed wastewater to adjust the pH value to 7.2, add the primary defluoridation agent calcium chloride 2.93g / L according to the molar concentration ratio of calcium ions and fluoride ions 1:1, and stir, and the primary defluoridation reaction is sufficient The mixed solution is added with flocculant polyaluminum chloride and coagulant polyacrylamide for primary sedimentation, the sediment is dehydrated through primary pressure filtration, and the filtrate of primary pressure filtration is merged into the effluent of primary sedimentation for secondary defluorination , Calcium fluoride is recovered from the mud cake produced by the primary filter press. The pH value of the p...

Embodiment 3

[0032] Alkali-transformed wastewater: Alkali-transferred wastewater produced during the alkali-transformation process of a bastnaesite rare earth smelter has a pH value of 12.2, a fluoride ion concentration of 398mg / L, and a discharge volume of 12m 3 / h.

[0033] Add concentrated hydrochloric acid to the alkali-transformed wastewater to adjust the pH value to 6.8, and add the first-level fluoride removal agent calcium chloride 1.74g / L according to the molar concentration ratio of calcium ions and fluoride ions at 3:4, and stir to achieve the first-level fluoride removal reaction. Fully proceed, the mixed solution is added with flocculant polyaluminum chloride and coagulant polyacrylamide for primary sedimentation, the sediment is dehydrated through primary filter press, and the filtrate of primary filter press is merged into the effluent of primary sedimentation for secondary dewatering Fluorine, calcium fluoride is recovered from the mud cake produced by the primary filter pr...

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Abstract

The invention discloses a method for removing fluoride ions in bastasite rare earth smelting wastewater, which comprises the first-stage and second-stage fluoride removal using different fluorine-removing agents, wherein the first-stage fluoride removal adopts fluoride-removing agent is chlorination Calcium, the defluoridation agent used in the secondary defluoridation is a rare earth element. The method of the invention can effectively remove and recycle the fluorine ions in the bastnaesite rare earth smelting wastewater, and avoid the generation of hazardous radioactive waste.

Description

technical field [0001] The invention belongs to the technical field of wastewater treatment in the rare earth smelting industry, and in particular relates to a treatment method for high fluorine-containing wastewater formed in the smelting process of bastnaesite rare earth ore. Background technique [0002] Bastnaesite mainly adopts the chemical treatment process derived from the oxidation roasting-hydrochloric acid leaching method as the main process to produce rare earth products. The process is to oxidize and roast bastnaesite, use hydrochloric acid to decompose to obtain a cerium-less rare earth chloride solution, enter tetravalent cerium, thorium, and fluorine into the slag, and then decompose and defluoride through caustic soda to obtain cerium-rich slag, or through Reductive leaching produces cerium oxide with a purity of 97-98%, and rare earth chlorides with less cerium undergo ammonia saponification P507 extraction to separate single rare earth or compound rare eart...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F9/04C02F103/16C02F101/14
Inventor 韩正昌刘大财张永飞许鹏飞薛超
Owner NANJING GW ENVIRONMENT ENG