CN117965918A - Method for recovering rare earth element from rare earth waste residue and application thereof - Google Patents
Method for recovering rare earth element from rare earth waste residue and application thereof Download PDFInfo
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- CN117965918A CN117965918A CN202410314061.9A CN202410314061A CN117965918A CN 117965918 A CN117965918 A CN 117965918A CN 202410314061 A CN202410314061 A CN 202410314061A CN 117965918 A CN117965918 A CN 117965918A
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 190
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 142
- 239000002699 waste material Substances 0.000 title claims abstract description 105
- 238000000034 method Methods 0.000 title claims abstract description 54
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 98
- 238000002386 leaching Methods 0.000 claims abstract description 67
- 239000007788 liquid Substances 0.000 claims abstract description 55
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 48
- 238000000926 separation method Methods 0.000 claims abstract description 30
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 claims abstract description 26
- 229910052776 Thorium Inorganic materials 0.000 claims abstract description 26
- 229910052742 iron Inorganic materials 0.000 claims abstract description 24
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 20
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000011574 phosphorus Substances 0.000 claims abstract description 19
- 239000012141 concentrate Substances 0.000 claims abstract description 18
- 238000003756 stirring Methods 0.000 claims abstract description 10
- 239000002893 slag Substances 0.000 claims description 53
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- -1 rare earth sulfate Chemical class 0.000 claims description 15
- 238000005406 washing Methods 0.000 claims description 12
- 239000012535 impurity Substances 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 8
- 238000007654 immersion Methods 0.000 claims description 8
- 239000000395 magnesium oxide Substances 0.000 claims description 8
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 8
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 8
- 230000003472 neutralizing effect Effects 0.000 claims description 8
- 238000013019 agitation Methods 0.000 claims description 5
- 238000006386 neutralization reaction Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 3
- 238000004364 calculation method Methods 0.000 description 11
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 10
- 229910052791 calcium Inorganic materials 0.000 description 10
- 239000011575 calcium Substances 0.000 description 10
- 230000008569 process Effects 0.000 description 9
- 239000002253 acid Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 238000000605 extraction Methods 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 238000001179 sorption measurement Methods 0.000 description 4
- 229910052770 Uranium Inorganic materials 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000009776 industrial production Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 239000000284 extract Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910004369 ThO2 Inorganic materials 0.000 description 1
- 238000006136 alcoholysis reaction Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000002925 low-level radioactive waste Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 238000000053 physical method Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 125000002924 primary amino group Chemical class [H]N([H])* 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 238000003904 radioactive pollution Methods 0.000 description 1
- 239000002901 radioactive waste Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- ZCUFMDLYAMJYST-UHFFFAOYSA-N thorium dioxide Chemical compound O=[Th]=O ZCUFMDLYAMJYST-UHFFFAOYSA-N 0.000 description 1
- VGBPIHVLVSGJGR-UHFFFAOYSA-N thorium(4+);tetranitrate Chemical compound [Th+4].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VGBPIHVLVSGJGR-UHFFFAOYSA-N 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- STCOOQWBFONSKY-UHFFFAOYSA-N tributyl phosphate Chemical compound CCCCOP(=O)(OCCCC)OCCCC STCOOQWBFONSKY-UHFFFAOYSA-N 0.000 description 1
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- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a method for recovering rare earth elements from rare earth waste residues and application thereof, wherein the method comprises the following steps: stirring and leaching the crushed rare earth waste residues with sulfuric acid solution with the pH value of 0.7-1 at 15-35 ℃, and carrying out solid-liquid separation to obtain rare earth leaching liquid and secondary waste residues; wherein the rare earth waste residue is waste residue generated by roasting rare earth concentrate with sulfuric acid; wherein the solid-liquid ratio of the rare earth waste residue and the sulfuric acid solution is 1kg (4-10) L. The method can recover rare earth elements from rare earth waste residues, greatly separate the rare earth elements from elements such as thorium, phosphorus, iron and the like, improves the relative separation degree and has mild conditions.
Description
Technical Field
The invention relates to a method for recovering rare earth elements from rare earth waste residues and application thereof.
Background
At present, most of Bayan obo rare earth concentrates are decomposed by adopting a concentrated sulfuric acid high-temperature roasting process, and each ton of decomposed rare earth concentrates containing 50% REO can generate more than about 0.6t of discharged waste residues, namely rare earth waste residues. The content (mass percent) of ThO 2 in the rare earth waste residue is about 0.25%, the content of REO is about 3.51% and the content of total iron is about 10%. Calculated by treating 12 ten thousand tons of mixed rare earth concentrate in a year, 7.2 ten thousand tons of waste slag are produced, and the REO loss of 2527t is caused. The rare earth waste residue can only be stored in a specific residue warehouse, so that the environment is polluted, valuable rare earth elements cannot be recycled, and great waste is caused. Therefore, the method has very important practical significance in reducing the rare earth waste residues and extracting and recycling the rare earth elements.
The rare earth recovery method is more, but most of the rare earth exists in the form of phosphate due to the close properties of iron and rare earth, and the difficulty is increased in the separation, extraction and recovery process.
CN116676486a discloses a method for recovering iron, phosphorus and rare earth from rare earth waste residue, which is to extract iron and phosphoric acid by using P 204 and tributyl phosphate respectively through sulfuric acid dissolution, and then recycle the sulfuric acid rare earth solution to water leaching process to recover rare earth. The method ensures that iron, phosphorus and rare earth in the rare earth waste residue are enriched and recovered in different treatment stages, but the extraction mode in the process is multistage countercurrent cascade extraction, thereby increasing the complexity of actual process operation and being inconvenient for industrial production.
CN103184343a discloses a method for recovering rare earth, thorium and iron from waste residue of rare earth acid process, comprising the following steps: mixing the waste residue with an acid solution, stirring and leaching at the temperature of 60 ℃ to boiling, extracting the leaching solution by primary amine, and back-extracting nitric acid to obtain a thorium nitrate solution; regulating the pH value of thorium extraction raffinate by alkali to precipitate iron; the filtrate is rare earth feed liquid. The recovery method solves the problem of radioactive waste residues in the acid process and realizes the comprehensive recovery and utilization of resources of the waste residues. However, the leaching temperature in the recovery method is higher, and the energy consumption is increased in the actual industrial production.
CN106148713a discloses a method for recovering and degrading rare earth slag, which comprises the following steps: (1) acid leaching; (2) ion adsorption; (3) catalytic degradation; (4) deep degradation. The method comprises the steps of carrying out acid leaching treatment on powder slag slurry, refining part of rare earth elements in rare earth slag, separating liquid phase from solid phase easily, and separating and extracting uranium and thorium elements in the liquid phase through ion adsorption materials; the solid phase is subjected to alcoholysis reaction by using a transition metal salt with moderate acidity and stable property as a catalyst. The method is characterized in that uranium, thorium and rare earth elements are leached out simultaneously, and then the uranium and the thorium are separated and extracted through an ion adsorption material.
In addition, the extracted thorium also needs to be separately stored by constructing a dam for a long time, so that a large amount of manpower, material resources and financial resources are consumed easily, and the accumulated stack after the extraction can cause larger radioactive pollution. Therefore, in view of the limited use of thorium at the present stage, it is of more practical importance to leave it as far as possible in the waste residue at the time of leaching.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a method for recovering rare earth elements from rare earth waste residues, which is advantageous for separating rare earth elements from elements such as thorium, phosphorus, iron, etc., and which has an improved relative separation degree and mild conditions. Another object of the present invention is to provide an application of a sulfuric acid solution having a pH of 0.7 to 1 in separating rare earth elements from thorium elements, phosphorus elements and iron elements from rare earth waste residues to improve the relative separation degree. The invention adopts the following technical scheme to realize the aim.
In one aspect, the invention provides a method for recovering rare earth elements from rare earth waste residues, comprising the following steps:
stirring and leaching the crushed rare earth waste residues with sulfuric acid solution with the pH value of 0.7-1 at 15-35 ℃, and carrying out solid-liquid separation to obtain rare earth leaching liquid and secondary waste residues;
Wherein the rare earth waste residue is waste residue generated by roasting rare earth concentrate with sulfuric acid;
wherein the solid-liquid ratio of the rare earth waste residue and the sulfuric acid solution is 1kg (4-10) L.
According to the method of the present invention, preferably, the particle size of the crushed rare earth waste residue is less than or equal to 100 meshes.
According to the method of the present invention, the sulfuric acid solution preferably has a pH of 0.7 to 0.8.
According to the method of the present invention, preferably, the temperature of the agitation leaching is 20 to 30 ℃.
According to the method of the present invention, preferably, the agitation leaching is performed for a period of 1 to 5 hours.
According to the method of the present invention, preferably, the solid-to-liquid ratio of the rare earth waste residue to the sulfuric acid solution is 1kg (6 to 8) L.
The method according to the invention preferably further comprises the steps of: and drying the rare earth waste residue, and crushing the dried rare earth waste residue to obtain crushed rare earth waste residue.
According to the method of the present invention, preferably, in the rare earth waste residue, REO content is less than 13.0wt%, caO content is more than 10.0wt%, thO 2 content is more than or equal to 0.08wt%, P content is more than or equal to 2.5wt%, and TFe content is more than or equal to 4.9wt%.
According to the method of the invention, preferably, the rare earth waste residue is waste residue generated by roasting rare earth concentrate with sulfuric acid, and the specific steps comprise: roasting the rare earth concentrate and concentrated sulfuric acid for 2-3 hours at the temperature of more than 400 ℃ to form rare earth sulfate roasting ore; leaching the rare earth sulfate roasting mine water to obtain pulp clear liquid and pulp slag; neutralizing the clear pulp liquid by magnesium oxide to remove impurities to obtain water immersion liquid and neutralized slag; the water immersion liquid is rare earth sulfate solution; the neutralization slag and the ore pulp slag are subjected to sulfuric acid washing to obtain slag washing clear liquid and secondary slag; and (3) washing the secondary slag with water, and then neutralizing and removing impurities by using magnesium oxide to obtain external slag, namely rare earth waste slag.
On the other hand, the invention also provides an application of the sulfuric acid solution with the pH value of 0.7-1 in separating rare earth elements from thorium elements, phosphorus elements and iron elements from rare earth waste residues to improve the relative separation degree, which comprises the following steps:
stirring and leaching the crushed rare earth waste residues with sulfuric acid solution with the pH value of 0.7-1 at 15-35 ℃, and carrying out solid-liquid separation to obtain rare earth leaching liquid and secondary waste residues;
Wherein the rare earth waste residue is waste residue generated by roasting rare earth concentrate with sulfuric acid;
wherein the solid-liquid ratio of the rare earth waste residue and the sulfuric acid solution is 1kg (4-10) L.
The method for recovering the rare earth elements from the rare earth waste residues does not need other physical and chemical methods to remove impurities, realizes the separation of the rare earth elements from thorium, phosphorus and iron elements to the maximum extent, simultaneously realizes the separation of the rare earth elements from calcium elements, basically extracts and recovers the rare earth elements, and greatly improves the relative separation degree and separation speed. In addition, the method can obviously reduce the amount of secondary waste residues and realize the reduction of the waste residues. In addition, the method disclosed by the invention is mild in condition, free of exhaust gas and waste liquid emission in the whole process, environment-friendly, simple in process and beneficial to industrial production.
Detailed Description
The present invention will be further described with reference to specific examples, but the scope of the present invention is not limited thereto.
The technical idea of the present invention is different from the prior art. The method for recovering the rare earth elements from the rare earth waste residues can realize the separation of the rare earth, thorium, phosphorus and iron to the maximum extent, and simultaneously realize the separation of the rare earth elements and calcium elements, and basically and independently extract and recover the rare earth elements. The method of the present invention is not a conventional option.
< Method >
The method for recovering rare earth elements from rare earth waste residues comprises the following steps: 1) Crushing; 2) Leaching and solid-liquid separation. Optionally, further comprising: a drying step and a recycling step. The following is a detailed description.
Drying step
And drying the rare earth waste residue to obtain the dried rare earth waste residue. The drying temperature can be 100-120 ℃, and the drying time can be 1-5 h.
The rare earth waste residue is waste residue generated by roasting rare earth concentrate with sulfuric acid, and the specific steps comprise: roasting the rare earth concentrate and concentrated sulfuric acid for 2-3 hours at the temperature of more than 400 ℃ to form rare earth sulfate roasting ore; leaching the rare earth sulfate roasting mine water to obtain pulp clear liquid and pulp slag; neutralizing the clear pulp liquid by magnesium oxide to remove impurities to obtain water immersion liquid and neutralized slag; the water immersion liquid is rare earth sulfate solution; the neutralization slag and the ore pulp slag are subjected to sulfuric acid washing to obtain slag washing clear liquid and secondary slag; and (3) washing the secondary slag with water, and then neutralizing and removing impurities by using magnesium oxide to obtain external slag, namely rare earth waste slag.
The roasting temperature is preferably 450-550 ℃, and the roasting time is preferably 2.5-3 h. In this step, the concentrated sulfuric acid used may be 80 to 95% by weight, preferably 85 to 95% by weight. Neutralization and leaching are referred to those known in the art and will not be described in detail herein.
The REO content in the rare earth waste residue is less than 13.0wt%, preferably less than or equal to 12wt%, more preferably less than or equal to 11.5wt%; the CaO content is more than 10.0 wt.%, preferably more than or equal to 11 wt.%, more preferably more than or equal to 12 wt.%, still more preferably more than or equal to 13 wt.%, still more preferably more than or equal to 14 wt.% and less than 15 wt.%; the ThO 2 content is 0.08wt% or more, preferably 0.09wt% or more, more preferably 0.1wt% or more; the P content is 2.5wt% or more, preferably 2.6wt% or more, and more preferably 2.7wt% or more; the TFe content is 4.9wt% or more, preferably 5.1wt% or more, more preferably 5.2wt% or more, still more preferably 5.3wt% or more.
Crushing step
Crushing the dried rare earth waste residue. The grain diameter of the crushed rare earth waste slag is less than or equal to 100 meshes. This is advantageous for maximum leaching of rare earth elements. The comminution may be carried out using equipment known in the art.
Leaching and solid-liquid separation step
Stirring and leaching the crushed rare earth waste residues with sulfuric acid solution with the pH value of 0.7-1 at 15-35 ℃, and carrying out solid-liquid separation to obtain rare earth leaching liquid and secondary waste residues. The invention surprisingly found that under the conditions of the invention, the separation of rare earth from thorium, phosphorus and iron can be maximized, and basically only rare earth elements are extracted and recovered.
Meanwhile, the invention can separate the rare earth element from the calcium element, and the separation degree of the rare earth element and the calcium is slightly lower, but the separation difficulty of the rare earth element and the thorium, the phosphorus and the iron is larger, so the invention focuses on the separation of the rare earth element and the thorium, the phosphorus and the iron, and simultaneously takes the separation of the rare earth element and the calcium into consideration.
In the present invention, the pH of the sulfuric acid solution may be 0.7 to 1, preferably 0.7 to 0.9, more preferably 0.7 to 0.8. When the pH of the sulfuric acid solution was 1, the molar concentration of H 2SO4 in the sulfuric acid solution was 0.05mol/L.
In the present invention, the solid-to-liquid ratio of the rare earth slag (i.e., the crushed rare earth slag) to the sulfuric acid solution may be 1kg (4 to 10) L, preferably 1kg (5 to 9) L, more preferably 1kg (6 to 8) L. For example, the solid to liquid ratio may be 1kg:6L, 1kg:6.5L, 1kg:7L, 1kg:7.5L, 1kg:8L.
In the present invention, the temperature of the agitation leaching may be 15 to 35 ℃, preferably 20 to 35 ℃, more preferably 20 to 30 ℃, still more preferably 20 to 25 ℃.
In the present invention, the time for agitation leaching may be 1 to 5 hours, preferably 1.5 to 4 hours, more preferably 2 to 3 hours.
The solid-liquid separation may be centrifugation or filtration, preferably filtration.
The rare earth leaching solution obtained by the method has higher rare earth content, the REO yield in the rare earth leaching solution reaches 35-56%, and the rare earth can be separated from other elements to the greatest extent. The rare earth leaching solution can be recycled to a water leaching process for leaching rare earth elements to obtain a sulfuric acid rare earth solution with higher concentration.
Calculation formula of rare earth leaching rate= (mass of REO in rare earth leaching solution/mass of REO in rare earth waste residue) ×100%.
Calculation formula of leaching rate of calcium= (mass of CaO in rare earth leaching solution/mass of CaO in rare earth waste residue) ×100%.
Calculation formula of leaching rate of thorium= (mass of ThO 2 in rare earth leaching solution/mass of ThO 2 in rare earth waste residue) ×100%.
Calculation formula of leaching rate of phosphorus= (mass of P in rare earth leaching solution/mass of P in rare earth waste residue) ×100%.
Calculation formula of leaching rate of iron= (mass of TFe in rare earth leaching solution/mass of TFe in rare earth waste residue) ×100%.
The secondary waste slag amount obtained by the method is obviously reduced, and the slag amount reduction is between 22 and 32 percent.
Calculation formula of slag amount reduction = [ (amount of rare earth slag-amount of secondary slag)/amount of rare earth slag ] ×100%.
The total radioactive discharge ratio of Th in the secondary waste residue is detected to be about 5.104 X10 4 Bq/kg, which is far lower than the storage standard of the specified low-level waste.
The invention has simple process, does not need to adopt physical methods such as adsorption and the like, and correspondingly improves the separation speed.
< Application >
The invention also provides an application of the sulfuric acid solution with the pH value of 0.7-1 in separating rare earth elements from thorium elements, phosphorus elements and iron elements from rare earth waste residues to improve the relative separation degree, which comprises the following steps:
Crushing rare earth waste residues, stirring and leaching the crushed rare earth waste residues with sulfuric acid solution with the pH value of 0.7-1 at 15-35 ℃, and carrying out solid-liquid separation to obtain rare earth leaching liquid and secondary waste residues;
wherein the rare earth waste residue is waste residue generated by roasting rare earth concentrate with sulfuric acid;
wherein the solid-liquid ratio of the rare earth waste residue to the sulfuric acid solution is 1kg (4-10) L. The details are as described above, and are not repeated here.
The test method is described as follows:
REO, caO and TFe contents were determined by a full spectrum direct-reading plasma emission spectrometer;
The ThO 2 content was determined by means of a plasma emission mass spectrometer;
The P content is determined spectrophotometrically.
The raw materials used are described below:
The rare earth waste residues used in the following examples and comparative examples are waste residues generated by roasting rare earth concentrate with sulfuric acid, and the specific steps include: roasting the rare earth concentrate and concentrated sulfuric acid for 3 hours at 500 ℃ to form rare earth sulfate roasting ores; the concentration of the concentrated sulfuric acid is 85wt%; the mass ratio of the concentrated sulfuric acid to the rare earth concentrate is 3:1; leaching the rare earth sulfate roasting mine water to obtain pulp clear liquid and pulp slag; neutralizing the clear pulp liquid by magnesium oxide to remove impurities to obtain water immersion liquid and neutralized slag; the water immersion liquid is rare earth sulfate solution; the neutralization slag and the ore pulp slag are subjected to sulfuric acid washing to obtain slag washing clear liquid and secondary slag; and (3) washing the secondary slag with water, and then neutralizing and removing impurities by using magnesium oxide to obtain external slag, namely rare earth waste slag.
The analysis of the components in the rare earth waste residue is shown in table 1.
TABLE 1
| REO(wt％) | CaO(wt％) | ThO2(wt％) | P(wt％) | TFe(wt％) |
| 11.28 | 14.15 | 0.11 | 2.72 | 5.39 |
Example 1
Drying the rare earth waste residue, crushing the dried rare earth waste residue, wherein the particle size of the crushed rare earth waste residue is less than or equal to 100 meshes.
And (3) stirring and leaching the crushed rare earth waste residues with sulfuric acid solution with the pH value of 0.8 for 1h at the temperature of 20 ℃ according to the solid-to-liquid ratio of 1kg to 8L, and filtering to obtain rare earth leaching liquid and secondary waste residues. The rare earth leaching solution is analyzed, and the main components are shown in Table 2, and the unit is g/L. Comprehensive calculation shows the leaching rate results of rare earth, calcium, thorium, phosphorus and iron in Table 3.
Example 2
Example 2 differs from example 1 only in that: the solid-to-liquid ratio is 1kg:6L; the pH of the sulfuric acid solution was 0.7; stirring and leaching for 2h.
The rare earth leaching solution is analyzed, and the main components are shown in Table 2, and the unit is g/L. Comprehensive calculation shows the leaching rate results of rare earth, calcium, thorium, phosphorus and iron in Table 3.
Example 3
Example 3 differs from example 1 only in that: the solid-to-liquid ratio is 1kg:6L; the temperature of the stirred leaching was 30 ℃.
The rare earth leaching solution is analyzed, and the main components are shown in Table 2, and the unit is g/L. Comprehensive calculation shows the leaching rate results of rare earth, calcium, thorium, phosphorus and iron in Table 3.
Comparative example 1
Comparative example 1 differs from example 1 only in that: the solid-to-liquid ratio is 1kg:6L; the pH of the sulfuric acid solution was 0.2.
The rare earth leaching solution is analyzed, and the main components are shown in Table 2, and the unit is g/L. Comprehensive calculation shows the leaching rate results of rare earth, calcium, thorium, phosphorus and iron in Table 3.
Comparative example 2
Comparative example 2 differs from example 1 only in that: the solid-to-liquid ratio is 1kg:6L; 4mol/L sulfuric acid solution is adopted; the temperature of the stirred leaching was 80 ℃.
The rare earth leaching solution is analyzed, and the main components are shown in Table 2, and the unit is g/L. Comprehensive calculation shows the leaching rate results of rare earth, calcium, thorium, phosphorus and iron in Table 3.
TABLE 2
TABLE 3 Table 3
TABLE 4 Table 4
Note that: in table 4, the relative separation degree of rare earth and thorium is the rare earth leaching rate/thorium leaching rate, and the others are the same.
In examples 1 to 3, the slag amount of the secondary slag was remarkably reduced, and the slag amounts of the secondary slag were 31%, 29% and 28%, respectively.
The present invention is not limited to the above-described embodiments, and any modifications, improvements, substitutions, and the like, which may occur to those skilled in the art, fall within the scope of the present invention without departing from the spirit of the invention.
Claims (10)
1. A method for recovering rare earth elements from rare earth waste residues, which is characterized by comprising the following steps:
stirring and leaching the crushed rare earth waste residues with sulfuric acid solution with the pH value of 0.7-1 at 15-35 ℃, and carrying out solid-liquid separation to obtain rare earth leaching liquid and secondary waste residues;
Wherein the rare earth waste residue is waste residue generated by roasting rare earth concentrate with sulfuric acid;
wherein the solid-liquid ratio of the rare earth waste residue and the sulfuric acid solution is 1kg (4-10) L.
2. The method of claim 1, wherein the crushed rare earth waste residue has a particle size of 100 mesh or less.
3. The method according to claim 1, wherein the sulfuric acid solution has a pH of 0.7 to 0.8.
4. The method according to claim 1, wherein the temperature of the stirred leaching is 20-30 ℃.
5. The method according to claim 1, wherein the agitation leaching is carried out for a period of 1 to 5 hours.
6. The method according to claim 1, wherein the solid-to-liquid ratio of the rare earth waste residue to the sulfuric acid solution is 1kg (6-8) L.
7. The method according to any one of claims 1 to 6, further comprising the step of: and drying the rare earth waste residue, and crushing the dried rare earth waste residue to obtain crushed rare earth waste residue.
8. The method of claim 7, wherein the rare earth slag has a REO content of less than 13.0wt%, a CaO content of greater than 10.0wt%, a ThO 2 content of greater than or equal to 0.08wt%, a P content of greater than or equal to 2.5wt%, and a TFe content of greater than or equal to 4.9wt%.
9. The method according to claim 8, wherein the rare earth waste residue is waste residue generated by roasting rare earth concentrate with sulfuric acid, and the specific steps include: roasting the rare earth concentrate and concentrated sulfuric acid for 2-3 hours at the temperature of more than 400 ℃ to form rare earth sulfate roasting ore; leaching the rare earth sulfate roasting mine water to obtain pulp clear liquid and pulp slag; neutralizing the clear pulp liquid by magnesium oxide to remove impurities to obtain water immersion liquid and neutralized slag; the water immersion liquid is rare earth sulfate solution; the neutralization slag and the ore pulp slag are subjected to sulfuric acid washing to obtain slag washing clear liquid and secondary slag; and (3) washing the secondary slag with water, and then neutralizing and removing impurities by using magnesium oxide to obtain external slag, namely rare earth waste slag.
10. Use of a sulfuric acid solution having a pH of 0.7 to 1 for separating rare earth elements from thorium elements, phosphorus elements and iron elements from rare earth waste residues to improve the relative degree of separation, characterized by comprising the steps of:
stirring and leaching the crushed rare earth waste residues with sulfuric acid solution with the pH value of 0.7-1 at 15-35 ℃, and carrying out solid-liquid separation to obtain rare earth leaching liquid and secondary waste residues;
Wherein the rare earth waste residue is waste residue generated by roasting rare earth concentrate with sulfuric acid;
wherein the solid-liquid ratio of the rare earth waste residue and the sulfuric acid solution is 1kg (4-10) L.
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