CN111634936A - Method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater - Google Patents
Method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater Download PDFInfo
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- CN111634936A CN111634936A CN202010465977.6A CN202010465977A CN111634936A CN 111634936 A CN111634936 A CN 111634936A CN 202010465977 A CN202010465977 A CN 202010465977A CN 111634936 A CN111634936 A CN 111634936A
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- C01F17/00—Compounds of rare earth metals
- C01F17/20—Compounds containing only rare earth metals as the metal element
- C01F17/253—Halides
- C01F17/265—Fluorides
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
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Abstract
The invention discloses a method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater, which comprises the following steps: s1, adjusting the pH value of the fluorine-containing wastewater mother liquor to 5-9 by using acid, then adding soluble calcium salt into the fluorine-containing wastewater mother liquor for reaction, filtering the fluorine-containing wastewater mother liquor after the reaction is finished, and removing filter residues; s2, adjusting the acidity of the mother liquor of the fluorine-containing wastewater obtained from S1 to 0.1 +/-0.05 mol/L by using acid, adding the acid as a precipitator into the slurried praseodymium-neodymium carbonate mixed liquor, and keeping the pH value of the whole solution system below 2.0 during the mixing reaction; and S3, after the reaction is finished, filtering to obtain filter residues, and performing subsequent treatment on the filter residues to obtain a praseodymium-neodymium fluoride product. The fluorine-containing wastewater generated in the bastnaesite wet smelting is used as a raw material for producing praseodymium neodymium fluoride, so that the problem of high cost in praseodymium neodymium fluoride production can be solved, fluorine resources in the fluorine-containing wastewater can be recovered, and the defects of the conventional praseodymium neodymium fluoride production process are overcome.
Description
Technical Field
The invention relates to the technical field of praseodymium neodymium fluoride production, in particular to a method for producing praseodymium neodymium fluoride by utilizing fluorine-containing wastewater.
Background
The rare earth fluoride is an important raw material for preparing rare earth metals and alloys by an oxide electrolysis method and a calcium thermal reduction method, and for praseodymium-neodymium alloy, praseodymium-neodymium fluoride is used as a raw and auxiliary material for electrolyzing metals to produce praseodymium-neodymium alloy, and domestic praseodymium-neodymium fluoride production processes are three: one is hydrofluoric acid method (wet method) prepared by adding hydrofluoric acid into praseodymium neodymium carbonate; the ammonia hydrogen fluoride method (dry method) prepared by ammonium bifluoride and praseodymium neodymium oxide; and thirdly, a hydrogen fluoride gas method (gas method) for directly preparing praseodymium neodymium oxide by fluoridizing hydrogen fluoride gas. The three methods are widely applied in production, at present, various problems are exposed in the application process of the three methods, the consumption of products produced by the ammonium bifluoride method in electrolysis is large, and the investment of ammonium recovery equipment is high; the hydrofluoric acid method has long working procedure, low rare earth recovery rate, large three-waste treatment capacity and high production cost; the hydrogen fluoride gas method has strict requirements on the performances of equipment tightness, corrosion resistance and the like, and the cost investment is large. Meanwhile, the three methods all need to purchase and add additional raw and auxiliary materials (hydrofluoric acid and ammonium bifluoride), so that the production cost of the praseodymium neodymium fluoride is increased, and by adopting the three methods, the treatment capacity of waste gas and waste water is not small, and the problem of consuming considerable cost to treat three wastes is solved. Therefore, it is necessary to develop a low-cost praseodymium neodymium fluoride production technology to overcome the deficiencies of the prior art.
In industrial production, do not generally directly adopt the mixed solution of praseodymium neodymium chloride to directly obtain praseodymium neodymium fluoride, lie in, directly deposit the praseodymium neodymium fluoride granule that mixed praseodymium neodymium chloride produced with hydrogen fluoride and be thinner, can form the colloid and suspend in deposiing the mixed solution in the process of deposiing, be difficult for washing and filtering, lead to praseodymium neodymium tombarthite recovery rate to reduce easily moreover, and the process of using hydrogen fluoride to deposit praseodymium neodymium carbonate is praseodymium neodymium ion and fluorine combination production praseodymium neodymium fluoride, and the praseodymium neodymium fluoride of output is the praseodymium neodymium fluoride that the granularity is great to deposit the separation effect relatively good, and easy washing also is difficult for causing praseodymium neodymium tombarthite to lose, therefore, what generally adopt is praseodymium neodymium carbonate.
In addition, the praseodymium neodymium chloride mixed solution is obtained by wet smelting of the fluorocarbon cerium bastnaesite, fluorine-containing wastewater with the fluorine concentration reaching about 35g/L is discharged in the production process, and the fluorine-containing wastewater is discharged after reaching the standard through fluorine removal treatment, so that the waste of fluorine resources is not only caused in the process, but also the wastewater treatment cost is increased in the process of treating the fluorine-containing wastewater, and the profit of enterprises is reduced.
Disclosure of Invention
The invention aims to: mainly aiming at the high cost problem existing in the existing praseodymium neodymium fluoride production, the method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater is provided, the fluorine-containing wastewater produced in the bastnaesite wet smelting is used as a raw and auxiliary material for producing praseodymium neodymium fluoride, the problem of high cost in praseodymium neodymium fluoride production can be solved, fluorine resources in the fluorine-containing wastewater can be recovered, the fluorine-containing wastewater treatment cost in the bastnaesite wet smelting is reduced, and the problems existing in the existing praseodymium neodymium fluoride production process and the bastnaesite wet smelting process are solved simultaneously.
The technical scheme adopted by the invention is as follows: a method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater is characterized by comprising the following steps:
s1, adjusting the pH value of the fluorine-containing wastewater mother liquor to 5-9 by using acid, then adding soluble calcium salt into the fluorine-containing wastewater mother liquor for reaction, filtering the fluorine-containing wastewater mother liquor after the reaction is finished, and removing filter residues;
s2, adjusting the acidity of the mother liquor of the fluorine-containing wastewater obtained from S1 to 0.1 +/-0.05 mol/L by using acid, adding the acid as a precipitator into the slurried praseodymium-neodymium carbonate mixed liquor, and keeping the pH value of the whole solution system below 2.0 during the mixing reaction;
and S3, filtering and taking filter residues after the mixed reaction of the fluorine-containing wastewater mother liquor and the praseodymium-neodymium carbonate mixed liquor is finished, and obtaining a praseodymium-neodymium fluoride product after the filter residues are subjected to subsequent treatment.
In the process, the fluorine-containing wastewater mother liquor is fluorine-containing wastewater obtained by oxidizing roasting, hydrochloric acid leaching and alkali transfer filtering of bastnaesite, the alkalinity of the fluorine-containing wastewater mother liquor generated by bastnaesite hydrometallurgy is 0.3-0.5 mol/L, the fluorine concentration is 30-35 g/L, and the fluorine-containing wastewater mother liquor also contains SO4 2－And AlO2 －When non-rare earth impurities exist, the fluorine-containing wastewater mother liquor exists in praseodymium and neodymium carbonate mixed reaction, and the existence of the non-rare earth impurities canInfluences the quality of the finally obtained praseodymium neodymium fluoride product, SO impurity removal is performed before the mixed reaction, however, SO4 2－And AlO2 －The non-rare earth impurities are not easy to remove, and in order to remove the impurities as much as possible, the impurity removal method adopted by the invention is as follows: adjusting the pH value of the fluorine-containing wastewater mother liquor to 5-9 by using acid, then adding soluble calcium salt into the fluorine-containing wastewater mother liquor for reaction, and finally filtering and removing impurities, wherein the impurity removal principle is as follows:
2F－+Ca2+＝CaF2↓
SO4 2－+Ca2+＝CaSO4↓
AlO2 －+4H+＝Al3++2H2O
Al3++3H2O＝Al(OH)3↓+3H+
according to the chemical reaction equation, the impurity removal method is used for removing the non-rare earth impurity SO in a precipitation mode4 2－And AlO2 －Etc., although F is removed simultaneously with the removal of impurities－However, since these non-rare earth impurities are present in small amounts, the amount of soluble calcium salt added is also small, in removing SO4 2－And AlO2 －When non-rare earth impurities are contained, the fluorine content is lost by about 3 percent, the fluorine content does not substantially influence the fluorine content of the fluorine-containing wastewater mother liquor, and the filtered filter residue can be sold as calcium fluoride residue after being dried, SO the method can be used for effectively removing SO in the fluorine-containing wastewater mother liquor4 2－And AlO2 －And the like non-rare earth impurities.
Further, after impurity removal treatment, acid is used for adjusting the acidity of the mother liquor of the fluorine-containing wastewater to be 0.1 +/-0.05 mol/L, the mother liquor is added into slurried praseodymium-neodymium carbonate mixed liquor as a precipitator for rare earth fluoride precipitation reaction, the pH value of the whole solution system is kept below 2.0 during the mixed reaction, and the reaction principle is as follows (PN represents praseodymium-neodymium):
PN2(CO3)3+6H+＝2PN3++3CO2↑+3H2O
PN3++3F－＝PNF3↓
after the precipitation is completed, the filter residue is washed, centrifuged, dried and dried to obtain a finished product, and the filtrate is used as fluorine-containing wastewater and transferred to a defluorination process for continuous treatment.
In the above-mentioned craft, the raw and auxiliary materials for producing praseodymium neodymium fluoride are waste water containing fluorine, the admixture is soluble calcium salt and acid, it compares with three kinds of praseodymium neodymium fluoride production methods now, has the following advantage:
1. can effectively recover fluorine resources in the fluorine-containing wastewater generated in part of the bastnaesite treatment;
2. the production cost can be effectively saved, namely, raw and auxiliary materials such as hydrogen fluoride, ammonium bifluoride and the like are not used;
3. the method does not need to add other equipment when treating the wastewater, and can reduce the cost of treating the wastewater;
4. the method does not generate other pollutants and extra treatment cost;
5. the method can be carried out on the original production equipment without adding other equipment.
Therefore, the invention uses the fluorine-containing wastewater produced in the bastnaesite wet smelting as the raw and auxiliary materials for producing praseodymium neodymium fluoride, which not only can solve the problem of high cost of praseodymium neodymium fluoride production, but also can recover fluorine resources in the fluorine-containing wastewater, thereby reducing the treatment cost of the fluorine-containing wastewater produced in the bastnaesite wet smelting, and solving the problems of the existing praseodymium neodymium fluoride production process.
In the present invention, the acid used is a hydrochloric acid solution, which is preferably industrial hydrochloric acid.
Further, the soluble calcium salt is one or more of calcium chloride, calcium bicarbonate and calcium hypochlorite, and is preferably calcium chloride.
Further, the fluorine concentration of the fluorine-containing wastewater mother liquor is 30 +/-5 g/L, and the REO content of praseodymium neodymium carbonate is not less than 45%.
Further, in S1, the obtained residue is dried and stored as a by-product.
Further, in the drying process, the drying temperature is controlled at 500-600 ℃.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
1. according to the invention, the fluorine-containing wastewater produced in the bastnaesite wet smelting is used as a raw material for producing praseodymium neodymium fluoride, so that the problem of high cost in praseodymium neodymium fluoride production can be solved, fluorine resources in the fluorine-containing wastewater can be recovered, the treatment cost of fluorine-containing wastewater produced in the bastnaesite wet smelting is reduced, and the problem of the existing praseodymium neodymium fluoride production process is solved;
2. the method is obtained by trial production, the recovery quantity of fluorine resources in the whole bastnaesite is about 35%, the direct yield of praseodymium-neodymium in praseodymium-neodymium fluoride can be ensured to be more than 99%, the method can completely replace the existing praseodymium-neodymium fluoride production method, the production cost is greatly reduced, and enterprises obtain considerable profits.
Drawings
FIG. 1 is a schematic diagram of the process flow of the method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, a method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater comprises the following steps:
s1, oxidizing and roasting bastnaesite, leaching with hydrochloric acid and carrying out alkali transfer filtration to obtain fluorine-containing wastewater, wherein the primary wastewater is used as mother liquor of the fluorine-containing wastewater for later use; wherein the alkalinity of the fluorine-containing wastewater mother liquor is 0.4 +/-0.1 mol/L, and the fluorine concentration is 30 +/-5 g/L;
s2, adjusting the pH value of the fluorine-containing wastewater mother liquor to 5-9 by using industrial hydrochloric acid, then adding a proper amount of calcium chloride into the fluorine-containing wastewater mother liquor for reaction, filtering the fluorine-containing wastewater mother liquor after the reaction is finished, drying filter residues to obtain filter residues which can be sold as calcium fluoride residues, and reserving the filtered fluorine-containing wastewater mother liquor for later use;
s3, adjusting the acidity of the fluorine-containing wastewater mother liquor of S2 to 0.1 +/-0.05 mol/L by using industrial hydrochloric acid, adding the obtained product as a precipitator into slurried praseodymium-neodymium carbonate mixed liquor, wherein the addition amount is 10-20% of theoretical value excess, REO is not less than 45% in the praseodymium-neodymium carbonate mixed liquor, and the pH value of the whole solution system is kept below 2.0 during mixing reaction;
s4, the mixed reaction of fluorine-containing wastewater mother liquor and praseodymium neodymium carbonate mixed liquor is accomplished, the filter residue is got in the filtration, the filter residue obtains praseodymium neodymium fluoride finished product after washing, centrifugation, spin-drying and stoving, the filter liquor is transferred to the defluorination process as low concentration fluorine-containing wastewater and is continued the processing, wherein, in the stoving process, the temperature control of stoving is at 500 + 600 ℃.
The quality of the praseodymium neodymium fluoride produced by the method reaches the market product requirement and is approved by customers, the direct yield of the praseodymium neodymium is more than 99%, and the recovery rate of the fluorine content in the whole bastnaesite is about 35%, so the praseodymium neodymium fluoride production method can completely replace the existing praseodymium neodymium fluoride production method.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. A method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater is characterized by comprising the following steps:
s1, adjusting the pH value of the fluorine-containing wastewater mother liquor to 5-9 by using acid, then adding soluble calcium salt into the fluorine-containing wastewater mother liquor for reaction, filtering the fluorine-containing wastewater mother liquor after the reaction is finished, and removing filter residues;
s2, adjusting the acidity of the mother liquor of the fluorine-containing wastewater obtained from S1 to 0.1 +/-0.05 mol/L by using acid, adding the acid as a precipitator into the slurried praseodymium-neodymium carbonate mixed liquor, and keeping the pH value of the whole solution system below 2.0 during the mixing reaction;
and S3, filtering and taking filter residues after the mixed reaction of the fluorine-containing wastewater mother liquor and the praseodymium-neodymium carbonate mixed liquor is finished, and obtaining a praseodymium-neodymium fluoride product after the filter residues are subjected to subsequent treatment.
2. The method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater as claimed in claim 1, wherein the acid used is a hydrochloric acid solution, and the hydrochloric acid solution is industrial hydrochloric acid.
3. The method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater according to claim 2, wherein the soluble calcium salt is one or more of calcium chloride, calcium bicarbonate, calcium hypochlorite, calcium oxide or calcium hydroxide.
4. The method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater according to claim 3, wherein the fluorine concentration of the mother liquor of the fluorine-containing wastewater is 30 ± 5g/L or more, and the REO content of praseodymium neodymium carbonate is not less than 45%.
5. The method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater as claimed in claim 1, wherein in S1, the obtained filter residue is dried and stored as a byproduct.
6. The method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater as claimed in claim 1, wherein in S3, the filter residue is washed, centrifuged, dried and dried to obtain a finished product, and the filtrate is transferred to a fluorine removal process as the fluorine-containing wastewater for further treatment.
7. The method of claim 6, wherein the drying temperature is controlled at 500-600 ℃ in the drying step.
8. The method for producing praseodymium neodymium fluoride by using fluorine-containing wastewater according to any one of claims 1 to 7, wherein the mother liquor of the fluorine-containing wastewater is the fluorine-containing wastewater obtained by subjecting bastnaesite to oxidizing roasting, hydrochloric acid leaching and alkali-shift filtration.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115259475A (en) * | 2022-08-23 | 2022-11-01 | 四川大学 | Method for removing fluorine by rare earth auxiliary precipitation |
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Application publication date: 20200908 |