Method for preparation of scandium oxide from red mud

FIELD: non-iron metallurgy, in particular scandium oxide recovery from industrial waste.

SUBSTANCE: method for preparation of scandium oxide from red mud being waste of alumina production includes: multiple subsequent leaching of red mud with mixture of sodium carbonate and hydrocarbonate solutions; washing and precipitate separation; addition into obtained solution zinc oxide, dissolved in sodium hydroxide; solution holding at elevated temperature under agitation; precipitate separation and treatment with sodium hydroxide solution at boiling temperature; separation, washing, and drying of obtained product followed by scandium oxide recovery using known methods. Leaching is carried out by passing through mixture of sodium carbonate and hydrocarbonate solutions gas-air mixture containing 10-17 vol.% of carbon dioxide, and repeated up to scandium oxide concentration not less than 50 g/m3; solid sodium hydroxide is introduced into solution to adjust concentration up to 2-3.5 g/m3 as calculated to Na2O (caustic); and mixture is hold at >=800C followed by flocculating agent addition, holding, and separation of precipitate being a titanium concentrate. Obtained mixture is electrolyzed with solid electrode, cathode current density of 2-4 A/dm3, at 50-750C for 1-2 h to purify from impurities. Zinc oxide solution in sodium hydroxide is added into purified after electrolysis solution up to ratio ZnO/Sc2O3 = (10-25):1, and flocculating agent is introduced. Solution is hold at 100-1020C for 4-8 h. Separated precipitate is treated with 5-12 % sodium hydroxide solution, flocculating agent is introduced again in amount of 2-3 g/m3, mixture is hold, and precipitate is separated. Method of present invention is useful in bauxite reprocessing to obtain alumina.

EFFECT: improved recovery ratio of finished product into concentrate; decreased impurity concentration in concentrate, reduced sodium hydrocarbonate consumption, as well as reduced process time due to decreased time of fine-dispersed precipitate.

2 cl, 2 ex

 

The invention relates to ferrous metallurgy, namely the recovery of scandium oxide from the waste in the processing of bauxite to alumina.

The method for extracting scandium oxide from waste alumina red mud, including leaching with sulfuric acid sorption on treated with sulfuric acid ion-exchange resin-based polyethylenepolyamines, sorption of scandium phosphate by ion exchange, subsequent washing of the resin, the desorption of scandium and processing the obtained eluate extraction of scandium oxide (patent No. 2196184, With 22 In 59/00, 2003).

But the known method has a number of disadvantages: complex technology use effectively when carrying out the extraction and sorption, poor environmental conditions due to the use of organics.

The closest to the technical nature of the claimed method is the extraction of scandium in the processing of bauxite to alumina, for example, from red mud, a by-product of processing, including the leaching of water and/or 5-12% solution of carbonate or sodium bicarbonate or mixtures thereof that are at least 3 times at a temperature not exceeding 50°for at least 2 hours at a ratio of T:W=1:2,5-5,0 using each time new portions of the product refining of bauxite as raw material separating the solution from osedc the, introduction to the resulting solution of aluminum oxide or zinc, dissolved in sodium hydroxide, the extract at a temperature not lower than 80°for at least 2 hours. The obtained precipitate was separated, washed and treated with 10-25%sodium hydroxide solution when heated to boiling, filtered and washed with 1-5%sodium hydroxide solution, and then dissolving the precipitate in 1-5%hydrochloric acid, filtered and the filtrate treated with 10-25%solution of ammonia or 2-10%hydrofluoric acid with an excess of 1-3% from stoichiometry accessing primary scandium concentrate (RF patent No. 2201988, IPC From 22 In 59/00, 2003).

The disadvantages of this method are:

substantial consumption of sodium bicarbonate and reduced extraction of scandium by leaching, a limited number of cycles of leaching of red mud one portion of a solution due to the increased content of sodium carbonate in excess of its solubility in the solution of sodium bicarbonate;

- getting poor scandium concentrate, enriched with some impurities;

- a considerable amount of time defending the drop-down fine precipitate of oxide of scandium.

Thus, the authors task was to develop a method to produce scandium oxide from red mud, waste from alumina production, which would have had a high adaptability n is the number of high extraction of scandium in the final product.

The proposed method provides the technical result consists in the high technological process along with the high extraction of scandium.

The technical result is achieved in the proposed method of producing oxide of scandium from red mud, waste from alumina production, including multiple sequential leaching of the red sludge is a mixture of solutions of carbonate and sodium bicarbonate, washing and separating the precipitate, introducing the resulting solution of zinc oxide dissolved in sodium hydroxide, the extract solution at elevated temperature and stirring, separating the precipitate and treated with a solution of sodium hydroxide at boiling point, separating, washing and drying the resulting product, followed by removing the oxide of scandium known methods, in which leaching through a mixture of solutions of sodium carbonate and sodium bicarbonate miss air-gas mixture containing 10-17% CO2(by volume), leaching repeat until you get a solution with a concentration of scandium oxide is not less than 50 g/m3injected in solution solid sodium hydroxide to a concentration of 2-3 .5 kg/m3in PA2Aboutcausticand maintained at a temperature not exceeding 80°followed by the introduction of the flocculant, endurance and sludge separation, which is the titans who m a concentrate, the resulting solution is subjected to electrolysis with solid electrodes at the cathode density 2-4 A/DM2and a temperature of 50-75°C for 1-2 hours to remove impurities, a solution of zinc oxide in sodium hydroxide added to purified after electrolysis solution to a ratio of ZnO:SC2O3=(10-25):1 and introducing the flocculant, the extract solution is carried out at 100-102°C for 4-8 hours, processing the separated precipitate lead 5-12% solution of sodium hydroxide at boiling point, again enter the flocculant, stand and separate the precipitate.

The flocculant can be used flocculant brand “Nalko” in the amount of 2-3 g/m3.

At the present time of patent and technical literature is not a method of obtaining oxide of scandium waste from alumina production, including the proposed process sequence with the parameters in the proposed range of values.

The proposed operating modes and parameters are explained by the following reasons.

Obtaining hydrogen from sodium carbonate directly into the apparatus by passing through the slurry of red mud CO2-containing gas mixture obtained, for example, purified and cooled flue gases from furnaces, sintering, calcining limestone and others)allows you to use more than the cheap and in a smaller amount of product, and secondary sodium carbonate, which is formed in the neutralization contained in the red mud Na2Aboutkuthe sodium bicarbonate, and reduces the consumption of soda derivatives;.

The use of CO2-containing gas allows you to adjust the content stored in the sodium carbonate solution, preventing the precipitation by reusing portions of the enriched solution that allows you to improve the content of scandium in the solution. In the used temperature range, there is increased resistance bicarbonate complex scandium and, consequently, its maximum extraction.

The proposed method uses the effect of increasing the activity of sodium bicarbonate at the time of its formation, through which more than 3% increases the extraction of scandium oxide into soluble bicarbonate complex.

Introduction scandium enriched solution solid sodium hydroxide in a certain amount and under certain conditions allows to partially separate the soluble compounds of titanium, iron, zirconium, etc., complexes which are destroyed when creating a slightly alkaline environment. These oxide compounds precipitate, while more strongly associated with hydrogen-ion scandium remains in solution, which allows you to receive an increased number of the GTC of the final product. Conducting electrolysis in the proposed conditions also aimed at improving the purity of the final product, ensuring reduced several times the content of iron, lead, copper, and other impurities.

Introduction of a solution of zinc oxide in the sodium hydroxide in the proposed correlation with the subsequent introduction of the flocculant and conducting high-temperature hydrolysis in the proposed conditions promotes the release of fine sediment, further processing which provides a high percentage of extraction of scandium oxide.

The proposed method is as follows.

In carbonization placed filtered red mud, water, carbonate (30-100 g/DM3) and sodium bicarbonate (50-100 g/DM3), the ratio of T:W=1:(2-5). The pulp is treated at a temperature of 50-60°With a gas mixture containing 10-17% (volumetric) CO2. In the carbonization process in storydorothy solution moving part of scandium oxide, sodium oxide contained in the liquid and in the solid phase of the sludge (20%), a number of compounds of titanium, iron, zirconium and others, as well as finely dispersed suspension consisting of oxides of silicon, iron, etc. the Use of CO2of the gas mixture in average close to 30%. After the operation, the solution advocated is separated from the precipitate. The latter is washed with water, which used the technology to compensate for water loss during carbonization. Thanks to the return of prambody loss of scandium and soda derivatives; with moisture sludge is negligible. The required concentration of sodium bicarbonate is supported by interaction of initial and secondary sodium carbonate with carbon dioxide. Temperature range due to the fact that at temperatures below 50°decreases the rate of leaching of sludge, and at temperatures above 60°With increased loss of solvent of sodium bicarbonate. The use of carbonate instead of sodium bicarbonate allows you to spend 1.68 times less soda derivatives; in addition, it uses the secondary sodium carbonate, the amount of which 1 operation carbonization is 15-19% (mass.) from the primary sodium carbonate. The use of carbon dioxide increases by 3% for the extraction of scandium in the solution, as the resulting sodium bicarbonate in the formation has a higher reactivity.

One portion stagedoorcabaret.com enriched solution using up to 10 times, accumulating at least 50 g/m3oxide of scandium. The number of operations is limited by the concentrations of bicarbonate and sodium carbonate in solution, since the excess of the solubility limit begins precipitation of solid phases.

Rich scandium storydorothy solution after carbonization and clarification of Podlachia the Ute with sodium hydroxide to a concentration of 2-3 .5 g/DM 3in PA2Aboutcaust.and subjected to hydrolysis at a temperature of 80°for at least 2 hours. The precipitation of the oxides of titanium, iron, zirconium, silicon is rich titanium concentrate [(56% Tio2and 3.5% ZrO2(mass.)]. Received codewelcome solution is electrolyzed at a cathode current density of 2-4 A/DM2the temperature of 50-75°C for 1-2 hours. In the electrolysis process several times decreasing concentration electrophoretically impurities such as iron, copper, lead. At the same time decreasing concentration in the colloidal form of the oxides of titanium and silicon, which can be explained by electrophoretic transfer to the cathode of the micelles and their discharge, whereby the oxides of titanium and silicon are also partially precipitate.

In purified codewelcome solution is injected zincate solution, based on the dosage of ZnO:Sc2O3=(10-25):1, introducing the flocculant is added and stirred the mixture at 100-102°C for 4-8 hours. In conditions of high temperature hydrolysis of solution precipitation, in which zinc oxide is a collector for scandium oxide. With less the stated excess zinc decreases the extraction of scandium oxide, the greater the excess does not affect the process, but is more poor concentrate, which creates additional difficulties in the subsequent operation is the removal of sediment oxide CIN is and. The wet sludge is fed to the leaching 5-12% solution of sodium hydroxide at 100°and With stirring.

At a concentration of less than 5% sodium hydroxide deteriorate the speed and completeness of the leaching of zinc oxide, at a concentration of more than 12% increase loss of scandium oxide.

In the known method by leaching of precipitation that results from the production of solutions, removing the sodium hydroxide solution zinc oxide is usually stopped after removal of 92-94%; in the proposed method, due to the removal of impurities when carrying out electrolytic cleaning increases the percentage of leachability of zinc oxide, resulting removes 95-98% of zinc oxide.

Uterine codewelcome solution after extraction of scandium passed in alumina production or partially used in the head process. Zincate solution after leaching the precipitate oxides used multiple times.

The precipitate of oxide of scandium is sucked from the zincate solution, washed and dried at 250°C. He is a rich concentrate containing up to 32% of scandium oxide. For the separation of finely dispersed precipitate of oxide of scandium enter the flocculant and give adequate exposure up to 6 hours for sedimentation. As a flocculant may be used flocculant “Nalko” No. 7864 in the form of a solution at a ratio of 2-3 g/m3.

Complete removal of the ACS is Yes scandium from red mud in concentrate average of 12.8% (mass.).

The proposed method is illustrated by the following examples.

Example 1. In a steel beaker 3,5 DM3(⊘150 mm, height 200 mm) - carbonization equipped with a stirrer, a cover, a bubbler and water jacket, placed 150 g PA2CO3and 30 g Panso3, 1.6 DM3water and 1 kg of waste red mud with a humidity of 25%. The composition of the sludge: solids, wt.%: Fe2O339-40, FO 6-7, Al2O312-14, SiO28-9, Cao 12-13, Tio23.5-4.0, PA2O 3-3 .5, ZrO20.16, si 0.08, Pb 0.05, Sc2O30.0125, nnn 14.0; liquid phase, g/DM3: PA2Oku8.0, Na2OKB0.4, Al2O31.6.

Through the pulp, consisting of 1.85 DM3liquid and 0.75 kg of the solid phase ratio (W:T=1:2,5), 6 hours of carbonization at a temperature of 60°miss 290 bat3the gas mixture containing 17% CO2. The carbonisation maintain a constant volume of slurry to compensate for the loss of water by adding located, obtained at wash leached slurry. Due to leaching losses soda derivatives; decrease by 3.3 g PA2O in a single operation.

Part Panso3- 19.8 g - spent on neutralization PA2Okucontained in the liquid and solid phases of the red sludge, respectively, 2.1 and 5.2 g, only 7.3 g PA2Oku. When this is formed in the solution 25.0 g PA2CO3. The absorption of CO2rest the rum when carbonization is on average 30%.

The mass of the precipitate obtained in the first and subsequent operations is ~1.0 kg at a moisture content of 25%.

The volume of filtrate after separating and washing the precipitate equal to 1.60 DM3and has a composition, kg/m3: PA2CO371.9, Panso360.1, Fe2O30.14, Al2O30.1, Tio20.7, ZrO20.02, Sc2O38.13·10-3(total in all volume of a solution of 13.0 mg). The resulting solution was used for the carbonization of the second portion of red mud in the above conditions. For carbonization of the second portion of the slurry for 2 hours in the pulp serves 65 NDM3gas mixture containing 17% (volumetric) CO2to compensate for Panso3by neutralizing PA2Okusludge and sediment washing. In the second operation receive 1.6 DM3leachate composition, kg/m3: PA2CO372.9; Panso365.1; Fe2O30.22; Al2O30.12; Tio21.38; ZrO20.058 and Sc2O315.3 g/m3(24.5 mg).

In subsequent operations, the carbonization is conducted so that in 3-5 operations, the content of hydrogen was within 65-68 kg/m3and 6-10 in the range of 70-75 kg/m3. The adjustment is the addition of PA2CO3in this case, do not hold. After running 5 operations carbonization receive 1.63 DM3leachate composition, kg/m3 : PA2CO381.9, Panso368.3, Fe2O30.27, Al2O30.14, Tio21.40, ZrO20.059 and Sc2O338.6 g/m3(62.9 mg). Extraction from sludge into solution in all operations for PA2O and Sc2O3remains approximately constant, the contents in the solution of the oxides of iron, titanium, aluminum, silicon, and other changes slightly.

Operations carbonation slurry in one portion of a solution continue up to 10 operations, after which they receive 1.68 DM3leachate composition, kg/m3: PA2CO398.5, Panso374.9, Fe2O30.62, Al2O30.17, Tio21.69, ZrO20.06, SiO20.23, C 0.046, N 0.056 and SC2O379 g/m3(132.0 mg).

In obtained after filtering the solution there is a significant amount of sediments consisting of fine and colloidal particles of compounds of iron, titanium, silicon, etc. For transfer to precipitate soluble in bicarbonate compounds of some hydroxides (Fe, Ti, Zr and others), and part of the suspended solids in the filtrate with stirring enter 65.3 g of solid sodium hydroxide to obtain a slightly alkaline solution, which corresponds to 2.5 kg/m3in PA2Ocaustic. After 2 hours of heating at 75-80°the solution is injected 1% solution of flocculant “Nalko” No. 7864 at the rate of 2 g/m3then after 6 hours of settling the precipitation is filtrowa and washed.

The dried and calcined precipitate weight 5.2 g contains, wt.%: Tio256.0; ZrO23.5; Fe2O325.9; SiO26.0; others (SiO2, Fe2O3, PA2O and others) 8.2; Sc2O35.1 mg or 0.16% of the mass of sediment.

Received codewelcome solution with a volume of 1.7 DM3composition, kg/m3: PA2CO3176.9, PA2Oku2.5, Al2O30.1, Fe2O30.04, Tio20.04, ZrO20.01, SiO20.05, si 0.036, Pb 0.05 and SC2O3At 74.20 g/m3(126,0 mg), is subjected to electrolysis at a current density of: cathode 2.0 A/DM2, volume 5 A/DM3temperature 75°With electrodes of acid-resistant steel. 2 hours of electrolysis, the concentration of a number of impurities is reduced and is, kg/m3: Fe2O30.003, Tio20.01, SiO20.03, Pb 0.005, C 0.004. Visually solution after settling more transparent. Later in the solution is injected at 0.05 DM3zincate solution (1.05 g Zn) concentration PA2Oku180 kg/m3and Zn 21 kg/m3(the ratio of the ZnO:SC2O3=10:1)add 3.2 mg flocculant “Nalko and maintained at a temperature of about 100°and With stirring for 4 hours. After 6 hours of settling filters precipitated crystalline precipitate. After washing and drying at 250°With the mass of sediment is 1.61 g, component content, % mass.: SC2O3 - 7.60 (0,122 g); ZnO - 81.80; Al2O3- 4.16; Fe2O3- 0.31; Tio2- 1.05; ZrO2- 0.37; SiO2- 3.10; si - 0.006; N - 0.1; other - 1.53.

Filtered codewelcome the solution is used to leach the next batch of red mud.

The wet precipitate of oxides within 2 hours treated at 100°and With stirring 12% solution of sodium hydroxide. At the end of the operation to impose 3.2 mg flocculant “Nalko and after 6 hours of settling the precipitate is filtered off scandium concentrate. After washing and drying at 250°With the mass of sediment is 0.41 g, composition, % (mass.): SC2O3- 29.70; ZnO - 11.82; Al2O3- 20.30; Tio2- 5.15; Fe2O3- 1.52; si - 0.30; Pb - 0.60; other - 6.98.

Next scandium concentrate processed by known techniques.

Consequently, the average extraction of scandium oxide from the slurry in storydorothy solution for 10 transactions amounts (including losses with moisture dump cake) 13.90%. Loss of scandium oxide in the operations comprise, % (mass.): separation of the precipitate hydroxides of titanium, zirconium, etc. - 3.8; contained in the solution; mechanical - 0.5%; the deposition of a mixture of oxides of scandium and zinc 3% and leaching of zinc oxide from the precipitate - 2%. Complete recovery of scandium oxide in the primary concentrate containing 29.70% SC2O3is 12.8%.

In the known method the calcined precipitate contains only 5-20% SC 2O3less than 1.5-5.9 times, and removing SC2O3from sludge to 3.0% lower. The duration of the bleaching solutions before filtering the known method is also 2-3 times the duration of the operation in the proposed method.

Example 2. Perform 10 operations carbonation as described in example 1, but using a gas mixture with a content of 10% (vol.) CO2at a temperature of 50°. The other conditions correspond to example 1. In the first operation amount of the gas mixture is 437 bat3period of 8.5 hours. In the second operation amount of the gas mixture is equal to 100 NDM3when the duration of 3 hours, in subsequent operations, the feed gas mixture is conducted from the calculation of the content of hydrogen in the solution 65-75 g/DM3. The content SC2O3after 10 operations is 77.4 g/m3(127.4 mg), which is 96.5% of the result in example 1. For transfer to precipitate soluble in bicarbonate compounds of some hydroxides (Fe, Ti, Zr and others), and part of the suspended solids in the filtrate with stirring introduce solid sodium hydroxide in the calculation of 2.5 kg/m3in PA2Ocausticto obtain a weakly alkaline solution. After 2 hours of soaking in the solution at 75-80°injected With 1% solution of flocculant “Nalko” No. 7864 at the rate of 3 g/m3then after 6 hours is taiwania the precipitation is filtered off, washed and calcined. The content Sc2O3in the sediment after the annealing is 0.08% (4.5 mg) or 3.2% from the original solution. Received codewelcome solution is electrolyzed at a cathode current density of 4.0 A/DM2temperature 50°With electrodes of acid-resistant steel. Visually solution after settling more transparent. Later in the solution is injected 2.5 g of zinc, based on the ratio of ZnO:SC2O3=25:1, the process is carried out at 102°C for 8 hours. The wet precipitate of oxides within 2 hours treated at 100°and With stirring with 5% sodium hydroxide solution. At the end of the operation to impose flocculant “Nalko” No. 7864 at the rate of 3 g/m3and after 6 hours of settling the precipitate is filtered off scandium concentrate, washed it and dried at 250°C.

Removing SC2O3of sludge in storydorothy solution is 13.6%. Loss SC2O3when receiving concentrate from stagedoorcabaret.com solution in operations, %: by separating the precipitate hydroxides of impurities - 3.2; deposition of ZnO and Sc2O3- 3.1; leaching ZnO - 2.5; mechanical - 0.5; total - 9.6.

Complete recovery (mass.) of sludge in concentrate amounts to 11.4% when the content of 30.6 wt.% Sc2O3.

Thus, the proposed method of producing oxide of scandium from red mud, waste production is odstv alumina, allows you to increase the percentage of extraction of the target product in the concentrate to reduce the content of impurities in the concentrate, as well as significantly reduce the consumption of sodium bicarbonate to reduce the duration of the process for reducing the time of the settling of fine sediment.

1. The method of producing oxide of scandium from red mud, a waste of alumina production, including multiple sequential leaching of the red sludge is a mixture of solutions of carbonate and sodium bicarbonate, washing and separating the precipitate, introducing the resulting solution of zinc oxide dissolved in sodium hydroxide, the extract solution at elevated temperature and stirring, separating the precipitate and treated with a solution of sodium hydroxide at boiling point, separating, washing and drying the resulting product, followed by removing the oxide of scandium known methods, wherein when leaching through a mixture of solutions of sodium carbonate and sodium bicarbonate miss air-gas mixture containing 10-17%2(by volume), leaching repeat until you get a solution with a concentration of scandium oxide is not less than 50 g/m3injected in solution solid sodium hydroxide to a concentration of 2-3 .5 kg/m3in Na2Ocausticand maintained at a temperature not exceeding 80°With posledovaniem flocculant, exposure and separation of the precipitate, which is the titanium concentrate, the resulting solution is subjected to electrolysis with solid electrodes at the cathode density 2-4 A/DM2and a temperature of 50-75°C for 1-2 h to remove impurities, a solution of zinc oxide in sodium hydroxide added to purified after electrolysis solution to a ratio of ZnO:Sc2O3=(10÷25):1 and introducing the flocculant, the extract solution is carried out at 100-102°C for 4-8 h, the processing of the separated sludge are 5-12%sodium hydroxide solution at boiling point, again enter the flocculant, stand and separate the precipitate.

2. The method according to claim 1, characterized in that as a flocculant use flocculant brand “Nalko” in the amount of 2-3 g/m3.



 

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8 cl, 1 dwg, 1 ex

FIELD: chemical technology; recovery of deactivated and decontaminated radioactive industrial wastes.

SUBSTANCE: proposed method that can be used for deactivating and decontaminating industrial radioactive wastes incorporating Tb-232 and their daughter decay products (Ra-228, Ra-224), as well as rare-earth elements, Fe, Cr, Mn, Sl, Ti, Zr, Nb, Ta, Ca, Mg, Na, K, and the like includes dissolution of wastes, treatment of solutions or pulps with barium chloride, sulfuric acid, and lime milk, and separation of sediment from solution. Lime milk treatment is conducted to pH = 9 - 10 in the amount of 120-150% of total content of metal oxyhydrates stoichiometrically required for precipitation, pulp is filtered, and barium chloride in the amount of 0.4 - 1.8 kg of BaCl2 per 1 kg of CaCl2 contained in source solution or in pulp, as well as pre-diluted sulfuric acid spent 5 - 20 times in chlorine compressors in the amount of 0.5 - 2.5 kg of H2SO4 per 1 kg of BaCl2 are introduced in filtrate. Alternately introduced in sulfate pulp formed in the process are lime milk to pH = 11 - 12, then acid chloride wash effluents from equipment and industrial flats at pulp-to-effluents ratio of 1 : (2 - 3) to pH = 6.5 - 8.5, and pulp obtained is filtered. Decontaminated solution is discharged to sewerage system and sediment of barium and calcium sulfates and iron oxysulfate are mixed up with oxyhydrate sediment formed in source pulp neutralization process; then 35 - 45 mass percent of inert filler, 10 - 20 mass percent of magnesium oxide, and 15 -m 25 mass percent of magnesium chloride are introduced in pasty mixture formed in the process while continuously stirring ingredients. Compound obtained is subjected to heat treatment at temperature of 80 - 120 oC and compressed by applying pressure of 60 to 80 at.

EFFECT: reduced radioactivity of filtrates upon separation of radioactive cakes due to enhanced coprecipitation of natural radionuclides.

7 c, 1 ex

FIELD: rare, dispersed and radioactive metal metallurgy, in particular hydrometallurgy.

SUBSTANCE: invention relates to method for reprocessing of polymetal, multicomponent, thorium-containing radwastes, formed when reprocessing of various mineral, containing rare-earth elements, Nb, Ta, To, V, Zr, Hf, W, U, etc. Method includes treatment of solution and/or slurry with alkaline agent; introducing of sulfate-containing inorganic compound solution and barium chloride; treatment of obtained hydrate-sulfate slurry with iron chloride-containing solution, and separation of radioactive precipitate from solution by filtration. As alkali agent magnesia milk containing 50-200 g/dm2 of MgO is used; treatment is carried out up to pH 8-10; sodium sulfate in amount of 6-9 g Na2SO4/dm2 is introduced as solution of sulfate-containing inorganic compound; barium chloride solution is introduced in slurry in amount of 1.5-3 g BaCl2/dm2. Hydrate-sulfate slurry is treated with solution and/or slurry containing 0.8-16 Fe3+/dm2 (as referred to startingsolution) of iron chloride, followed by treatment with high molecular flocculating agent and holding without agitation for 0.5-2 h. Radioactive precipitate is separated from mother liquor, washed with water in volume ratio of 0.5-2:1; then washed with sodium chloride-containing solution and/or slurry in volume ratio of 0.5-2:1; radioactive precipitate is removed from filter and mixed with mineral oxides in amount of 0.5-0.8 kg MgO to 1 kg of precipitate. Formed pasty composition is fed in forms and/or lingots and presses with simultaneous heating up to 80-1200C.

EFFECT: filtrate with reduced radioactivity due to increased codeposition coefficient of natural Th-232-group radioactive nuclide, in particular Ra-224 and Ra-228, with radioactive precipitates.

10 cl, 1 ex

The invention relates to a method of extracting magnesium from containing magnesium material, such as magnesite, dolomite and silicate type of serpentine residues, products amphibolite and pyroxene groups

The invention relates to the field of non-ferrous metallurgy and can be used for other industries that are toxic arsenic-bearing materials

The invention relates to hydrometallurgy, in particular to the purification of copper electrolyte from impurities and can be used in the chemical industry in acidic solutions from impurities

The invention relates to a method of recovering chlorine from solutions obtained in the chemical, pulp and paper and steel industry, and can be used in the recovery of gold from solutions containing active chlorine

FIELD: chemical technology; deactivation and decontamination of radioactive industrial products and/or wastes.

SUBSTANCE: proposed method designed for deactivation and decontamination of radioactive industrial products and/or production wastes incorporating Th-232 and its daughter decay products (Ra-228, Ra-224), as well as rare-earth elements, Fe, Cr, Mn, Al, Ti, Zr, Nb, Ta, Ca, Mg, Na, K, and the like and that ensures high degree of coprecipitation of natural radionuclides of filtrates, confining of radioactive metals, and their conversion to environmentally safe form (non-dusting water-insoluble solid state) includes dissolution of wastes, their treatment with barium chloride, sulfuric acid, and lime milk, and separation of sediment from solution. Lime milk treatment is conducted to pH = 9-10 in the amount of 120-150% of that stoichiometrically required for precipitation of total content of metal oxyhydrate; then pulp is filtered and barium chloride is injected in filtrate in the amount of 0.4 - 1.8 kg of BaCl2 per 1 kg of CaCl2 contained in source solution or in pulp and pre-dissolved in sulfuric acid of chlorine compressors spent 5-20 times in the amount of 0.5 - 2.5 kg of H2SO4 per 1 kg of BaCl2. Then lime milk is added up to pH = 11 - 12 and acid chloride wash effluents of equipment and production floors are alternately introduced in sulfate pulp formed in the process at pulp-to-effluents ratio of 1 : (2-3) to pH = 6.5 - 8.5. Filtrate pulp produced in this way is filtered, decontaminated solution is discharged to sewerage system, sediment of barium and calcium sulfates and iron oxysulfate are mixed up with oxyhydrate sediment formed in source pulp neutralization, inert filler and 0.5 - 2 parts by weight of calcium sulfate are introduced in pasty mixture while continuously stirring them. Compound obtained in the process is placed in molds, held therein at temperature of 20 - 50 oC for 12 - 36 h, and compacted in blocks whose surfaces are treated with water-repelling material.

EFFECT: reduced radioactivity of filtrates upon separation of radioactive cakes.

8 cl, 1 dwg, 1 ex

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