RU2484164C1 - Method of producing scandium-bearing concentrate from red mud - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: proposed method comprises sulfuric acid leaching of scandium from red mud, pulp filtration, scandium sorption from sulfuric acid solutions, desorption from organic phase by carbonate solution to obtain column effluent. Then, scandium poorly soluble compounds are precipitated from column effluent, precipitate is filtered out, flushed, dried and annealed to get scandium-bearing concentrate. Note here that said leaching is performed by 10.0-13.5%-sulfuric acid at pulp initial vibration cavitation at rotary velocity of 35-60 m/s for 15-35 min. Scandium is precipitated from column effluent by potassium caprinate in amount of 75-100 g/t of scandium at pH 3.5-4.5 and exposure for 15-25 min.

EFFECT: increased yield.

3 cl, 2 tbl, 2 ex

Description

The invention relates to non-ferrous metallurgy, namely to the integrated processing of red mud from alumina production.

There is a method of extracting scandium from red mud of an alumina production based on pyrometallurgical processing of such and subsequent sulfatization of a processed product - belite sludge (Derevyankin VA, Saltanov VV and others. "An improved version of the pyrohydrochemical technology for processing red mud". - Transactions of YOU “Problems of alumina production in the USSR.” L .: 1990, p. 101). The method includes pyrometallurgical processing of red mud at 1200-1400 ° C into a metal product and aluminum-calcium slag, soda processing of the latter to produce a belite slurry, sulfation of the belite slurry at 200 ° C for 1 hour with concentrated (90.0%) sulfuric acid, aqueous leaching of sulfate mass at 50 ° C for 45.0-60 min to obtain a scandium-containing sulfate solution, precipitation of scandium from the solution with organic complexones (polyamine derivatives) at a flow rate of precipitators of 150-200 g / g Sc, filtering the precipitate, drying y and calcining the latter to obtain a scandium-containing concentrate. The extraction of scandium in concentrate from the initial content in the red mud is ~ 65%, and the concentration in the concentrate is 10-15 wt.%.

The disadvantages of this method are primarily associated with the complexity and multi-stage technological process of processing red mud as such, including high-temperature annealing, soda leaching, sulfation by concentrated sulfuric acid and only then obtaining scandium-containing concentrate from the obtained scandium-containing solution.

This also leads to an insufficiently high degree of extraction of scandium from the initial red mud, and the use of polyamine derivatives as an organic scandium precipitator results in a low concentration of the latter in the concentrate, because at the same time there is a quantitative (85-95%) precipitation of iron, aluminum, titanium and REE ions .

A known method of extracting scandium from red mud, including leaching of red mud first 3-5% hydrochloric acid at 20-25 ° C and a ratio of T: W = 1: 5-10, then subsequent treatment with 50-55% sulfuric acid at 100-110 ° C and the ratio T: W = 1: 6-8 (RF patent No. 2040587, C22B 59/00).

Then, from the obtained scandium-containing sulfuric acid solution, scandium is further concentrated by known methods — sorption and / or extraction — followed by elution of scandium from the organic phase with a solution of sodium carbonate, acidification of the solution, precipitation of scandium from the solution with an alkaline reagent, drying and calcination of the precipitate to obtain a scandium-containing concentrate (Korshunov B .G., Reznik A.M. et al. Scandium. M.: Metallurgy, 1987).

This method of hydrochemical extraction of scandium from red mud has several disadvantages. This is primarily a two-stage leaching of red mud, and in the second stage, sulfuric acid of high concentration is used, which leads to a significant recovery of macrocomponents - Fe, Al, Ti, the concentration of which in the obtained sulfuric acid solution is many times (500-1000 times) higher than the concentration of scandium (0 , 02-0.03 g / dm ³ ); this necessitates a 2-3-stage sorption and / or extraction of scandium to obtain sufficiently pure scandium-containing solutions, which not only complicates the process, but also reduces the through extraction of scandium from red mud to concentrate up to 65-70%.

The closest in technological essence, the totality of the features and the achieved technical result is a method for producing scandium-containing concentrate from various industrial wastes, including from red mud from alumina production.

The method consists in the following (RF patent No. 2048564, C22B 59/00).

The acid leaching of red mud from alumina production is carried out with solutions of hydrochloric (20-25% HCl) or sulfuric acid (20-30% H ₂ SO ₄ ), then the pulp is filtered or centrifuged, sorption extraction of scandium from the obtained acid solution is carried out, sorbent washed to wash off partially sorted impurity ions: aluminum, iron, titanium, desorb scandium with a carbonate-containing solution to obtain an eluate, then scandium-containing eluate is treated with mineral acid to pH≤1.0, an alkaline reagent is introduced to obtain pH values of 1.8-2.2, hold at 60-100 ° C for 15-60 minutes, separate the oxyhydrate precipitate of impurities from the solution by filtration, poorly soluble scandium compounds precipitate from the filtrate, separate the precipitate by filtration, wash, dry and calcine with obtaining scandium-containing concentrate.

The disadvantages of this method are the relatively low through extraction of scandium in the target product due to the multi-stage process and also the low content of scandium in such a product due to the significant transition of impurity macrocomponents when highly concentrated solutions of mineral acids are used to leach red mud.

The technical result is the provision of conditions for increasing the degree of extraction of scandium and an increase in the content of scandium in the target product.

This goal is achieved by a method for producing scandium-containing concentrate from red mud of alumina production, which includes acid leaching of red mud, centrifugation or filtration of pulp, sorption extraction of scandium from acidic solutions, washing of the sorbent, desorption of scandium with a carbonate-containing solution to obtain an eluate, precipitation from the eluate of malate eluate, scandium, filtering, washing, drying and calcining the precipitate to obtain a scandium-containing concentrate, and differs from earlier from estno process so that leaching of red mud is carried out with solutions of mineral acids, relatively low concentrations in vibrokavitatsionnom mode, and the deposition of scandium from the product further after sorption-desorption eluate is conducted with an organic precipitant - caprate potassium (K [CH ₃ (CH _{2) 8} COO]) - with certain technological parameters.

The above set of distinctive features provides a technical result, which consists in increasing the degree of extraction of scandium and increasing its content in the target product.

Example 1 (prototype). The leaching of red mud from alumina production is carried out, containing, wt.%: 46.0 Fe ₂ O ₃ , 10.5 Al ₂ O ₃ , 9.0 SiO ₂ , 7.5 CaO, 4.5 TiO ₂ , 4.0 Na ₂ O, 0.011 Sc, 0.035 ZrO ₂ , 0.05 Y ₂ O ₃ , 0.03 GeO ₂ , 0.03 LaO ₅ , 0.005 ThO ₂ - 20% sulfuric acid at 90-95 ° C, ratio W: T = 5: 1 and a duration of 90 minutes Next, the pulp is filtered, and the obtained scandium-containing solution containing, g / dm ³ : 55.0 Fe ₂ O ₃ , 15.0 Al ₂ O ₃ , 1.0 TiO ₂ , 0.02 Sc, 0.02 Zr, 0, 06 Y ₂ O ₃ , 0.05 GeO ₂ , 0.005 ThO ₂ , 100 H ₂ SO _{4 sv} - in an amount of 1.0 dm ³ are brought into contact under dynamic conditions with 10.0 g of phosphate ampholyte, for example API-22 or ANKF -80; sorption was performed until scandium ions appeared in the filtrate (0.002 g / dm ³ ). Next, the ion exchanger was washed with 1.0 N HCl in an amount of 0.1 dm ³ and scandium was desorbed with a 3.0 N sodium carbonate (Na ₂ CO ₃ ) solution under dynamic conditions, passing through the ion exchanger in an amount of 0.1 dm ³ to obtain the eluate (pH 9.5) containing, g / dm ³ : 0.2 Sc, 0.5 Zr, 1.0 Ti, 0.6 Y ₂ O ₃ , 0.65 Fe, 0.70 Al, 0.02 Y, 0.001 Th. The eluate is neutralized to a pH of 0.8, the solution is heated to 70 ° C and incubated for 10 minutes with stirring. The neutralized solution was alkalinized with an alkaline reagent (NaOH solution) to a pH of 2.0 and further maintained at 70 ° C for 45 minutes with stirring. The precipitated oxyhydrate precipitate of impurities is separated from the solution by filtration, the filtrate is made alkaline with a NaOH solution to pH 6.0 and kept at 80 ° C for 90 minutes. The precipitate formed is filtered off, washed, dried and calcined at 750 ° C for 60 minutes to obtain a scandium-containing concentrate.

Through recovery of scandium in the target product amounted to:

0.75 · 0.94 · 0.96 = 0.67 or 67.0% (where 75.0, 94.0 and 96.0 are the degrees of scandium recovery, respectively, when red mud is leached, sorption-desorption and extracted from the eluate concentrate), and the content of Sc ₂ O ₃ in the concentrate was 20.5%.

Example 2. The acid leaching of this red mud is carried out at the following process parameters: temperature 90-95 ° C, ratio W: T = 5: 1, sulfuric acid concentration 12.5%, the total leaching time is 90 min, at the beginning of 25 min the treatment is carried out pulp in a vibro-cavitation mixer with a value of the peripheral speed of the rotor of the mixing device ω = 45 m / s. Next, the pulp is filtered and the resulting scandium-containing solution containing, g / dm ³ : 10.0 Fe ₂ O ₃ , 10.0 Al ₂ O ₃ , 0.2 TiO ₂ , 0.025 Sc, 0.01 Zr, 0.03 Y ₂ O ₃ , 0.001 ThO ₂ , 40 H ₂ SO _{4 sv} - in an amount of 1.0 dm ³ are brought into contact under dynamic conditions with 10.0 g of phosphate ampholyte, for example API-22 or ANKF-80; sorption was carried out before the "slip" (the content of scandium in the filtrate of 0.002 g / DM ³ ). Next, the ion exchanger was washed with 1.0 N HCl in an amount of 0.1 dm ³ and scandium was desorbed with a 3.0 N sodium carbonate solution under dynamic conditions in an amount of 0.1 dm ³ to obtain an eluate containing, g / dm ³ : 0.3 Sc, 0.1 Zr, 0.12 Ti, 0.25 Fe, 0.40 Al, 0.01 Y, 0.0003 Th. The eluate was further acidified to pH 4.0, an organic precipitant, potassium caprinate (K [CH ₃ (CH ₂ ) ₈ COO]), was introduced as a 0.1 M solution in terms of a dosage of 85 g of reagent / g of scandium in solution and holding the resulting pulp for 20 minutes The precipitate was isolated in a laboratory flotation machine.

The precipitate was washed on a filter, dried and calcined at 750 ° C for 60 min to obtain a scandium-containing concentrate.

Through recovery of scandium in the target product amounted to:

0.80 · 0.94 · 0.98 = 0.737 or 73.7% (where 80.0, 94.0 and 98.0 are the degree of scandium extraction, respectively, when red mud is leached in vibro-cavitation mode, sorption-desorption cycle and extraction from the eluate to the concentrate using an organic precipitant), and the content of Sc ₂ O ₃ in the concentrate was 25.0%.

Tables 1 and 2 show the results of experiments on obtaining scandium-containing concentrate from red mud during the implementation of the technological process according to the claimed invention, as well as when going beyond the optimal limits of the parameters.

Table 1 shows the results on the degree of extraction of scandium and its content in the concentrate when varying the parameters of sulfate leaching from red mud, ceteris paribus, the technological process as a whole:

- leaching: temperature 90 ° C, the ratio W: T in the initial pulp 5: 1, the total duration of the process is 90 minutes;

- precipitation with caprinate of potassium from the eluate: pH 4.0, dosage of organic reagent 85 g / g Sc ³⁺ , exposure 20 min.

Table 1 The results of experiments during the implementation of the process with the optimal leaching of scandium, ceteris paribus Experience number Leaching parameters The degree of extraction of scandium, η,% The content of Sc ₂ O ₃ in concentrate,% C _H2SO4 ,% value of ω, m / s vibration processing time, min prototype 67.0 20.5 one 10.0 60 fifteen 70.0 23.0 2 12.5 45 25 73.7 25.0 3 13.5 35 35 74.5 22.5 when exceeding the optimal parameter limits four 8.5 45 25 63.0 21.7 5 15.0 45 25 77.0 16.7 6 12.5 25 25 65.5 20.8 7 12.5 70 25 74.5 18.7 8 12.5 45 10 66.0 21.0 9 12.5 45 45 74.8 18,4 10 8.5 25 10 60.0 22.0 eleven 13.5 70 45 79.0 17.5

Thus, as can be seen from table 1, the optimal conditions for sulfuric acid leaching of scandium from red mud, providing, all other things being equal (when scandium is precipitated from potassium capricate eluate), the achievement of the required technical result is an increase in the degree of extraction of scandium in the concentrate and an increase in its content in the target the product are the following (op.1 ÷ 3):

- concentration of sulfuric acid (H ₂ SO ₄ ) - 10.0-13.5%;

- the value of the peripheral speed (ω) of the rotor with vibrocavitation mixing, m / s - 35-60;

- the duration of the initial vibration cavitation treatment of sulphate pulp - 15-35 minutes

When going beyond the optimal limits of the parameters of the technological mode of leaching:

- a decrease in the concentration of sulfuric acid is less than 10% H ₂ SO ₄ - there is a decrease in the degree of extraction of scandium to 63.0% (option 4); this is also caused by a decrease in the time of vibro-cavitation treatment to 10 min (op. 8) η _Sc = 66.0%, which is less than the required technical result;

- a decrease in the peripheral speed of the rotor of the mixing device during vibro-cavitation treatment to 25 m / s (option 6) also leads to a decrease in the degree of extraction of scandium to 65.5%, i.e. less than in the known invention;

- an increase in one or all three parameters above the upper optimal limit — sulfuric acid concentration up to 15.0% (op. 5), peripheral speed values up to 70 m / s (op. 7) or vibro-cavitation treatment time up to 45 min (op. 9) although it leads to an increase in the degree of extraction of scandium in concentrate to 74-77%, but significantly reduces its content in the target product to 17.5-18.5%. This is due to a simultaneous increase in the extraction of elements such as titanium, zirconium, rare earth elements (yttrium, cerium, lanthanum) from red mud, which also, together with scandium, are partially sorbed on phosphate ion exchangers and then are precipitated with potassium caprinate from carbonate-containing eluate.

Table 2 shows the results on the degree of extraction of scandium and its content in the concentrate when varying the parameters of deposition of scandium from the eluate, ceteris paribus, the process as a whole:

- leaching: sulfuric acid concentration (H ₂ SO ₄ ) - 12.5%, temperature 90 ° C, ratio W: T = 5: 1, total duration 90 minutes, duration of vibro-cavitation treatment 25 minutes at a peripheral speed of 45 m / s .

table 2 The results of experiments during the implementation of the process with the optimal deposition of scandium from the eluate of potassium caprinate Experience number Deposition parameters The degree of deposition of Sc from the eluate The degree of extraction of Sc in concentrate The content of Sc ₂ O ₃ in concentrate,% dosage org. reagent, g / g Sc pH value deposition time, min prototype - 67.0 20.5 12 70 3,5 fifteen 92.0 69.0 26,4 13 85 4.0 twenty 98.0 73.7 25.0 fourteen one hundred 4,5 25 97.0 72.8 22.0 when exceeding the optimal parameter limits fifteen 85 3.0 twenty 84.0 63.0 21.0 16 85 5,0 twenty 86.0 64.5 19.0 17 60 4,5 twenty 83.5 62.6 22.0 eighteen 110 4,5 twenty 98.5 74.0 17.0 19 85 4,5 10 85.5 64.0 21.0 twenty 85 4,5 thirty 98.0 73.5 19.5 21 60 3.0 10 78.0 58.5 18.0 22 110 5,0 thirty 89.5 67.0 16.5

Thus, as can be seen from Table 2, the optimal conditions for the deposition of scandium by potassium caprinate from the eluate obtained after the sorption-desorption cycle, providing, all other things being equal (when scandium is sulfuric leached from red mud in vibro-cavitation mode), the achievement of the required technical result is an increase in the degree of extraction scandium in concentrate and increasing its content in the target product are the following (op.12 ÷ 14):

- dosage of potassium caprinate in an amount of 70-100 g / t of scandium in the initial solution (eluate);

- the pH of the deposition of 3.5 ÷ 4.5;

- the duration of the deposition of 15 ÷ 25 minutes

When going beyond the optimal limits of the parameters of the technological mode of deposition:

- the exit of one or all parameters beyond the lower limit of optimal conditions - a decrease in the precipitation pH to 3.0 (op.15), or a dosage of potassium caprinate to 60 g / g (op.17), or a deposition time of up to 10 min (op.19 ) - leads to a significant decrease in the degree of deposition of scandium from the eluate by an organic precipitant, and therefore, the degree of extraction of scandium from red mud to the concentrate as a whole, respectively, to 83.5-85.5% and ~ 63-64%, which is less than the required technical result;

- the exit of one or all parameters beyond the upper limit of optimal conditions - increasing the pH to 5.0 (op.16), the dosage of the precipitant to 110 g / g (op.18) or the deposition time to 30 min (op.20) leads to either reducing the degree of deposition of scandium from the eluate to 86.0% (option 6), and therefore to concentrate up to 64.5%, or with a positive effect, maintaining the degree of deposition of scandium from the eluate at the highest possible level of 98.0-98, 5% (op. 18, 20 and 22) - leads to a significant decrease in the content of scandium in the target product to ~ 17-19%, which is caused by an increase in the degree of deposition of caprino m of potassium associated scandium components from carbonate eluate - titanium, zirconium, rare earth elements.

So, only the process of obtaining scandium-containing concentrate from red mud under optimal conditions: leaching of scandium from red mud by 10.0-13.5% sulfuric acid with vibrocavitation initial pulp treatment at a peripheral speed of 35-60 m / s for 15 -35 min and the subsequent precipitation of scandium from the eluate obtained after the sorption-desorption cycle with potassium caprinate at a dosage of 70-100 g / g scandium at a pH of 3.5-4.5 and holding for 15-25 min, the conditions for increasing the degree of extraction of scandium in concentration t and an increase in its content in the target product, respectively, up to ~ 70.0-75.5% and 22.5-25.0% or increase, compared with the known invention (prototype), respectively, 3.0-7.5% and 2.5-4.5%.

Claims (3)

1. A method of obtaining a scandium-containing concentrate from red mud, including sulfuric acid leaching of scandium from red mud, filtering the pulp to obtain a sulfuric acid solution, sorbing scandium from a sulfuric acid solution, washing the sorbent, desorbing scandium with a carbonate-containing solution to obtain an eluate, acidifying the eluate and precipitating the eluate and precipitating the eluant and eluate sludge filtration, washing, drying and calcining the sludge to obtain scandium-containing concentrate, characterized in that sulfuric acid leaching initially lead in vibro-cavitation mode, and the precipitation of scandium from the eluate is carried out by caprinate of potassium. 2. The method according to claim 1, characterized in that the leaching of scandium from red mud is carried out with 10.0 ÷ 13.5% sulfuric acid, initially in vibro-cavitation mode, at a peripheral speed of 35-60 m / s and a duration of 15-35 min . 3. The method according to claim 1, characterized in that the precipitation of scandium from the obtained eluate with potassium caprinate is carried out at a dosage of 70-100 g / g of scandium at a pH of 3.5-4.5 and an exposure of 15-25 minutes