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CN-117684028-B - Method for recycling scandium oxide from scandium-containing oxalic acid wastewater

CN117684028BCN 117684028 BCN117684028 BCN 117684028BCN-117684028-B

Abstract

The application belongs to the technical field of rare earth element recovery, and discloses a method for recovering scandium oxide from scandium-containing oxalic acid waste water, which comprises the steps of firstly mixing a phosphoric acid extractant and solvent oil to prepare a mixed solution I, filtering scandium-containing oxalic acid waste water, mixing the mixed solution I with the filtered scandium-containing oxalic acid waste water according to the volume ratio of an organic phase to an aqueous phase of 1:20-30, carrying out countercurrent extraction, stirring and clarification to obtain a mixed solution II, then back-extracting an organic phase in the mixed solution II by using an alkaline solution doped with ethanol to obtain scandium hydroxide, then acid-dissolving scandium hydroxide by using a hydrochloric acid solution, finally precipitating scandium oxalate by using an oxalic acid solution to obtain scandium oxalate, and calcining scandium oxalate in a high-temperature environment to obtain scandium oxide, wherein the scandium oxide recovery rate of the application reaches 97.9%, and meanwhile, the scandium oxide recovered by the method has purity of not less than 99.5%.

Inventors

  • QIU YEHONG
  • CAO SHENG
  • JIAN DAN
  • YIN LIANG

Assignees

  • 广东先导稀材股份有限公司

Dates

Publication Date
20260505
Application Date
20231102

Claims (4)

  1. 1. A method for recovering scandium oxide from scandium-containing oxalic acid wastewater, which is characterized by comprising the following steps: Step 1, mixing a mixed extractant of phosphoric acid extractant C272 and P507 with light white oil, wherein the mass ratio of the mixed extractant to the light white oil is 20:80, and the mass ratio of the C272 to the P507 in the mixed extractant is 1:1, so as to obtain a mixed solution I; Step 2, filtering scandium-containing wastewater, mixing the mixed solution I prepared in the step1 with the filtered scandium-containing wastewater according to the volume ratio of an organic phase to an aqueous phase of 1:20-30, performing 1-3-level countercurrent extraction, and then stirring and clarifying to obtain a mixed solution II; Step 3, back-extracting the organic phase in the mixed solution II prepared in the step 2 by using an alkaline solution to obtain scandium hydroxide; step 4, acid-dissolving scandium hydroxide prepared in the step 3 by using a hydrochloric acid solution, precipitating scandium by using an oxalic acid solution to obtain scandium oxalate, and calcining the scandium oxalate at the temperature of 650-850 ℃ for 2-4 hours to obtain scandium oxide; The alkaline solution in the step3 is a mixed alkaline solution prepared by mixing sodium hydroxide and ammonia water, and ethanol with the mass fraction of 0.1-3% is doped in the mixed alkaline solution.
  2. 2. The method for recovering scandium oxide from scandium-containing wastewater according to claim 1, wherein the scandium-containing wastewater is scandium-containing wastewater containing simple substances or scandium ions.
  3. 3. The method for recycling scandium oxide from scandium-containing oxalic acid wastewater according to claim 1, wherein the step 3 is characterized in that an organic phase in the mixed solution II prepared in the step 2 is back extracted by an alkaline solution doped with ethanol, the reaction temperature is 70-80 ℃, the volume ratio of the organic phase to the water phase is 1:1-1.2, and the reaction time is 0.5-2 h, so that scandium hydroxide is obtained.
  4. 4. The method for recycling scandium oxide from scandium-containing oxalic acid wastewater according to claim 1, wherein the scandium hydroxide prepared in the step 4 is subjected to acid dissolution by using 1-3 mol/L hydrochloric acid solution according to a solid-to-liquid ratio of 1:3-6, scandium precipitation is performed by using oxalic acid solution, the ratio of the molar quantity of oxalic acid to the molar quantity of scandium hydroxide in the oxalic acid solution is 1.8-2.1:1, the reaction time is 1-4 h, the reaction temperature is 60-70 ℃, scandium oxalate is obtained after the reaction is finished, and scandium oxide is obtained by calcining scandium oxalate for 2-4 h under the condition of 650-850 ℃.

Description

Method for recycling scandium oxide from scandium-containing oxalic acid wastewater Technical Field The application relates to the technical field of rare earth element recovery, in particular to a method for recovering scandium oxide from scandium-containing oxalic acid wastewater. Background Scandium (Sc) is widely available in nature, has low average abundance, is about 36×10 -4% in crust, but is extremely dispersed, often gives extremely rare impressions, and meanwhile, independent scandium mineral resources are extremely rare, most scandium is dispersed in the form of mineral accompaniment in tungsten, aluminum, vanadium, titanium, zirconium ore deposits and part of rare earth ores, and research on extraction and deep processing is difficult. Scandium and compounds thereof are mainly applied to the aspects of Al-Sc alloy materials, scandium sodium halogen lamps, solid oxide fuel cells and the like, and the price of the scandium is relatively high due to the extremely rare scandium mineral resources, so that the scandium is limited to be widely applied in the fields of aviation, laser, electronics and the like. At present, although companies producing scandium and related products at home and abroad are more, the total yield is not high, and according to the international Hadamard information research center data, the demand for scandium is huge in the future internationally, and the situation of supply and demand is long-term. Therefore, in order to relieve the unbalanced supply and demand relationship of scandium, the recycling of scandium from different materials in various channels has important significance. At present, oxalic acid solution is generally adopted to precipitate scandium metal in the production process of scandium oxide, but the precipitated oxalic acid waste liquid has large volume and high acidity and also contains a trace amount of valuable scandium metal. For the treatment of oxalic acid waste liquid, alkaline substances are generally selected for neutralization treatment and then discharged, the mode causes high energy consumption and high cost, meanwhile, the produced calcium oxalate is difficult to treat and has environmental protection risks, or a series of acid recovery measures such as re-separation and impurity removal are carried out on the waste acid, the process is tedious, the equipment is complex and the production cost is high, and impurities are easily enriched in products and the purity of the products is reduced due to direct reprecipitation of oxalic acid waste liquid. Therefore, the reasonable disposal of oxalic acid waste liquid is important. Chinese patent application 200910090880.5 discloses a process for extracting and separating rare earth elements, which at least comprises the following steps: (1) The method comprises the steps of simultaneously or stepwise mixing a blank organic extractant, an organic acid salt aqueous solution of magnesium and/or calcium and a rare earth solution to perform pre-extraction, extracting rare earth ions into an organic phase, clarifying to obtain a loaded organic phase and a raffinate aqueous phase, wherein the rare earth content REO in the loaded organic phase is 0.05-0.23mol/L, the pH value of the raffinate aqueous phase is 1.5-5, and the magnesium and/or calcium organic acid salt aqueous solution is prepared from magnesium and/or calcium minerals through a roasting-organic acid dissolving method; (2) The loaded organic phase containing rare earth ions is used for extracting and separating rare earth feed liquid containing 2 or more rare earth elements, and raffinate, washing and back extraction liquid products containing different rare earth elements are obtained through multistage extraction, washing and back extraction, or the loaded organic phase containing rare earth ions is directly back extracted by hydrochloric acid or nitric acid to obtain mixed rare earth chloride solution or mixed rare earth nitrate solution containing REO0.1-2mol/L, and the solution is concentrated and crystallized to produce mixed rare earth chloride or mixed rare earth nitrate products, or further extracted and separated to produce single rare earth compound products; the scheme is that an acidic organic extractant such as P507, P204, C272, naphthenic acid and the like is mixed with an organic acid salt aqueous solution of magnesium and/or calcium and a rare earth solution to extract rare earth ions into an organic phase, the rare earth ions are clarified to obtain a loaded organic phase containing the rare earth ions for the extraction and separation of mixed rare earth feed liquid, and the single rare earth compound or the enrichment of a plurality of rare earth compounds is obtained through multistage extraction and separation. The magnesium and/or calcium organic acid salt aqueous solution is prepared from magnesite, limestone, calcite, dolomite and other minerals through roasting-organic acid dissolution, the content of impurities such as