CN1005565B - Method for extracting scandium oxide from artificial rutile - Google Patents

Abstract

The invention proposes a method for extracting scandium oxide from artificial rutile. Without destroying the structure and quality of the original rutile product, scandium can be effectively separated and recovered from the high-acid high-titanium acid leaching solution by sulfuric acid leaching, organic solvent extraction, and oxalic acid precipitation. The process of leaching, extraction and purification is simple, only need secondary extraction, stripping and secondary precipitation to obtain products containing Sc ₂ O ₃ >99.9%, and the total recovery rate of Sc ₂ O ₃ is above 83%.

Description

Method for extracting scandium oxide from artificial rutile

The invention relates to a method for recovering scandium from a mixture containing scandium, titanium, zirconium and the like by using sulfuric acid leaching, organic solvent extraction and oxalic acid precipitation, in particular to a method for separating and recovering scandium from artificial rutile.

The decomposition of black tungsten concentrate with hydrochloric acid and the use of P is described in non-ferrous metals 1981, 11 th, 13 th page₂₀₄Extracting scandium from the acidolysis solution with kerosene solution of sec-octanol as extractant in the ratio of organic phase to water phase of 1: 5, back extracting with 2.5N NaOH solution in the ratio of organic phase to water phase of 3: 1 to obtain scandium hydroxide precipitate, and burning to obtain Sc₂O₃And (5) a product process. However, the process test is still insufficient, and problems such as scandium oxide purification and the like need further research. Furthermore, for scandium oxide extraction from synthetic rutile, leaching with sulfuric acid, the pickle liquor contains TiO₂The material which is high in titanium and scandium trioxide content and has acidity of more than 18N and is as high as 50-80 g/L is difficult to implement by the existing method.

The invention aims to provide a method for extracting scandium oxide from artificial rutile. Under the condition of not destroying the structure and the quality of the original rutile product, scandium in the rutile product is leached by sulfuric acid, and the scandium is effectively separated and recovered from the high-acidity high-titanium acid leaching solution.

The technological composition of the present invention is that the synthetic rutile is leached with 60% concentration sulfuric acid solution in the solid-to-liquid ratio of 1 to 1 at 120 deg.c for 1 hr without re-grinding, so that the non-rutile TiO is obtained₂And most of the iron and about 50% of Sc₂O₃Leached out, and the leached residue is not destroyed after being washed, still exists in rutile type, and contains TiO because impurities in the leached residue are removed₂The grade of (A) can be improved by one level.

And (2) standing the leached filtrate, crystallizing to separate out titanyl sulfate crystals, filtering to remove the titanyl sulfate crystals, diluting the rest mother liquor to 13N acidity by using slag washing water, and using the mother liquor as a scandium extraction feed liquid (I), wherein the filtered titanyl sulfate crystals absorb part of dissolved scandium, and are dissolved by using the slag washing water to recover the absorbed scandium, and the scandium is filtered and used as a scandium extraction feed liquid (II). The method comprises the following steps of extracting a feed liquid I and a feed liquid II by using 15-30% of di- (2-ethylhexyl) phosphoric acid, 0-5% of tributyl phosphate and a kerosene solvent in an organic phase/water phase ratio of 1: 3-15 and extraction stages of 1-5, and carrying out back extraction on a loaded organic phase by using 0.8-2.5N NaOH solution in an organic phase/water phase ratio of 1: 0.8-2.0. Filtering the hydroxide obtained by back extraction, dissolving the filter residue with 4N-6N sulfuric acid at acidity of 0.1N-2NH₂SO₄Hydrolyzing under the condition of the solution to obtain metatitanic acid and scandium-rich liquid, filtering to remove metatitanic acid, wherein metatitanic acid contains 0.15-0.5% of Sc₂O₃And extracting after acid dissolution.

The solution after the titanium is removed by water contains Sc₂O₃300-1300 mg/l, TiO₂0.1-4 g/l, Fe0.2-2 g/l, re-extracting the solution with the organic phase under the conditions, and subjecting the loaded organic phase to secondary extraction with 5% NaCl and 1NH₂O₂H of (A) to (B)₂SO₄Washing iron and titanium with the solution, and then using the NaoH solutionAnd carrying out back extraction to obtain the scandium concentrate.

For purification, the scandium concentrate was dissolved in 1: 1 industrial hydrochloric acid and further water-stripped of titanium and zirconium. Since the scandium concentrate inevitably contains sulfate radicals, it is dissolved in hydrochloric acid, the solution is heated to a temperature above 80 ℃, diluted with water and neutralized to a pH of 1-2, in which case the titanium is replaced with metatitanic acid (H)₂TiO₃) Precipitation, zirconium as basic sulphate (ZrO)₂∶SO₃About 1: 0.3) precipitation. The metatitanic acid and zirconium basic sulfate can be filtered and removed, and filter residues are treated in a centralized manner.

Precipitating the filtrate with industrial oxalic acid saturated solution, washing the precipitate with water, filtering, drying and burning to obtain coarse scandium. Dissolving the coarse scandium with 1: 1 analytically pure hydrochloric acid solution, and precipitating with analytically pure oxalic acid to obtain Sc-containing solution₂O₃Greater than 99.9% product.

The method provided by the invention can extract scandium from rutile, the granularity and structure of the original rutile product are not destroyed, the original rutile product still exists in rutile type, and the quality of the original rutile product is improved, and the grade of the original rutile product is improved from the grade of the original rutile product containing TiO₂88.26% to 92.65% without other impurities, can effectively recover scandium from the high acid (18N) and high titanium (50-80 g/L) feed liquid to a higher degree, has simple extraction process, only needs two times of extraction and back extraction in the enrichment and purification process, and can obtain Sc more than 99.9% by two times of oxalic acid precipitation₂O₃The product and the back extraction operation basically solve the common emulsification problem, so that the organic phase and the water phase are separated quickly and do not stick to the wall.

The following examples further illustrate the operation of the present invention.

The operation steps for carrying out this example are illustrated in the order shown in fig. 1.

The 1.8 ton synthetic rutile was treated with 1800 liters of 60% H₂SO₄Leaching with solution, i.e. 1542L of the extracted feed liquid obtained in the first and second steps, containing Sc₂O₃56 mg ofPer liter, TiO₂55.83 g/l, Fe21.25 g/l, H⁺12.8N, 1009L of feed liquid and Sc₂O₃84 mg/l, TiO₂38.61 g/l, Fe31.50 g/l. H⁺9.45N。

The feed liquid (3 a) is subjected to single-stage extraction by using 20 percent of di- (2-ethylhexyl) phosphoric acid (P204), 4 percent of tributyl phosphate (TBP) and a kerosene solvent according to the volume ratio of an organic phase to a water phase of 1: 9, and the raffinate contains Sc₂O₃5.6 mg/l, TiO₂52.8 g/l, Fe19.63 g/l, H⁺12.4N, and returning to the acid preparation in the first step. The liquid medicine (3 b) is extracted in single stage with the same extractant in the volume ratio of 1 to 8, and the raffinate contains Sc₂O₃2.9 mg/l, TiO₂36.82 g/l, the Fe content was unchanged. H⁺8.8N, and discharging the raffinate after being neutralized by lime. Sc of feed liquid (i) in this step₂O₃Extraction rate is 90%, and Sc of feed liquid is₂O₃The extraction rate is 96.37 percent, and the Sc in the two feed liquids₂O₃The average actual extraction was 93.24%.

Back extracting the loaded organic phase with 2N NaOH solution in the ratio of organic phase to water phase of 1 to 1, filtering in the fifth step, dissolving the filter cake with 4-6N sulfuric acid solution to obtain scandium containing solution, adding hot water to eliminate titanium in the seventh step, filtering in the eighth step, and adding H to the obtained filter residue-metatitanic acid solid in the ninth step₂SO₄And after the dissolution, repeating the operation of the third step to the eighth step. 193L of Sc are obtained in total in two times₂O₃800 mg/l scandium-rich solution and 0.85 kg Sc₂O₃0.4% metatitanic acid sludge (left for next treatment).

Extracting said scandium-rich liquid in the third step with 1: 5 ratio of organic phase/aqueous phase of extracting agent, and extracting raffinate containing Sc₂O₃1.25 mg/l, discarded. This step Sc₂O₃The extraction rate of (D) was 99.84%. 6NH for organic phase loaded in the first generation₂SO₄+6.2% NaCl 3 times in 2: 1 organic/aqueous phase and 4NH₂SO₄+1NH₂O₂Washing 4 times according to the ratio of organic phase to water phase being 2: 1, and returning the washing waste liquor to the sixth step for use. The washed loaded organic phase is back extracted with industrial pure 2.5N naoH solution at the ratio of organic phase to water phase of 1: 1 in the third step to obtain scandium hydroxide, which is filtered in the third step, dried and burned at 700 deg.C for 0.5 hr to obtain scandium concentrate 320 g containing Sc₂O₃47.5%。

The scandium concentrate is dissolved in a 1: 1 solution of industrial hydrochloric acid (step a), diluted with water and neutralized to a pH of 1-2 (step a), and the titanium is removed by heating with water (e.g. the zirconium contained therein can also be removed at the same time). Filtering out hydrolysis residue (step III), concentrating and post-treating, adding industrial oxalic acid into filtrate at 80 deg.C to precipitate scandium oxalate, filtering, washing, drying, and burning at 850 deg.C for 0.5 hr to obtain 152.1 g of coarse scandium oxide containing Sc₂O₃The content was found to be 96%. The said coarse scandium is repeatedly processed by analytically pure hydrochloric acid and oxalic acid to obtain scandium oxide product 142.5 g containing Sc₂O₃More than 99.9 percent, wherein Zr is less than 0.001 percent. Sc of two oxalic acid precipitations₂O₃The recovery was 93.75%. From the leached scandium-containing solution to a Sc of > 99.9%₂O₃Product, Sc₂O₃The overall recovery was 83.28%.

Claims (2)

1. A method for extracting scandium oxide from scandium-containing materials, comprising the following main steps: leaching with an inorganic acid, extraction with di-(2-ethylhexyl)phosphoric acid, stripping with a NaOH solution, and precipitation with oxalic acid. The method is characterized in that scandium in artificial rutile is leached with 60% sulfuric acid, titanyl sulfate is precipitated by the acid leaching solution after standing, titanyl sulfate is removed by filtration, the mother liquor is diluted with slag washing water to an acidity of 13N and then used as a feed solution for extracting scandium. The filtered titanyl sulfate solid is also dissolved with the slag washing water, and the filtrate after filtering out insoluble impurities is used as the extraction liquid. Take scandium feed solution ②, extract feed solution ① and feed solution ② with 15-30% di-(2-ethylhexyl)phosphoric acid + 0-5% tributyl phosphate + kerosene solvent, with the ratio of organic phase:aqueous phase = 1:3-15, and the number of extraction stages being 1-5, the loaded organic phase is stripped with 0.8-2.5N NaOH solution, the stripped hydroxide is dissolved with 4-6N sulfuric acid, hydrolyzed to remove titanium, the scandium-rich solution after titanium removal is subjected to secondary extraction with the organic solvent under the conditions, the loaded organic phase is washed with a sulfuric acid solution containing NaCl and _H2O2 , and stripped with the _NaOH solution, the stripped hydroxide is filtered, calcined, dissolved with hydrochloric acid, scandium oxalate is precipitated with oxalic acid, and then calcined to convert it into scandium oxide. 2. The method according to claim 1, characterized in that when dissolving scandium oxide with hydrochloric acid, the solution is diluted with water and neutralized to pH = 1-2 for hydrolysis to further remove titanium and zirconium contained in the raw material is also removed at the same time.