RU2576562C1 - Method for columbite concentrate processing - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to method of columbite concentrate processing. Method involves development of concentrate with mixture of sulphuric acid and hydrofluoric acid, pulp filtration to separate cake, which is washed and delivered for further processing. Then, collective counterflow extraction of tantalum and niobium from solution containing niobium and tantalum is made using octanol followed with extract washing. This is followed by selective re-extraction of niobium and tantalum, wherein resulted extract of niobium is subject to additional de-tantalizing. These resulted extract are sent for individual processing and decomposition into respective elements. Note here that prior to filtration the pulp is cooled, and before extraction the filtrate is mixed with flushing water. Washing of extract is carried out with a mixture of sulphuric and hydrofluoric acids. Niobium re-extraction is performed with sulphuric acid solution and re-extraction of tantalum - with softened water.

EFFECT: high efficiency of process due to extraction from concentrate of not less than 96 % niobium oxide and tantalum oxide and producing high-quality compounds of niobium and tantalum.

6 cl, 2 dwg, 5 tbl

Description

The invention relates to hydrometallurgical processing of ore concentrates, mainly to the processing of columbite concentrate, and can be used to extract compounds of niobium and tantalum from ores of other deposits or rare metal concentrates.

In recent decades, niobium and tantalum have become one of the most important factors in scientific and technological progress, and with the development of new branches of production and technology, their role increases. Niobium and tantalum have unique physical and chemical properties (refractoriness, heat resistance, ductility, corrosion resistance, magnetic capacity), due to which they are used in a number of areas of technology, namely in the manufacture of electrolytic capacitors (tantalum, niobium), steel alloying (niobium) , heat-resistant and heat-resistant alloys, in chemical engineering, etc.

There is a steady demand for niobium-tantalum products in the world. In this regard, the involvement in the production of new deposits of niobium-tantalum raw materials and the development of effective technologies for producing products based on niobium and tantalum is an urgent task.

Most types of niobium and tantalum deposits are highly complex and contain associations of minerals: phosphorus, zirconium, rare earth metals, scandium, strontium, barium, iron, titanium, thorium (alkaline deposits) or tantalum, beryllium, rubidium, cesium, tin ores (granites and pegmatitis). The main minerals containing tantalum and niobium: columbite, tantalite, pyrochlore, loparite, manganotantalite, vzhinit, ixiolite, microlite, plumbomicrolite, are known in pegmatites of granite and alkaline rocks, carbonatides, and also hydrothermal veins.

In some industrial sources of raw materials, in particular in columbite, niobium and tantalum coexist as the main beneficial components. Complex tantalum-niobium deposits are considered to be deposits in which tantalum and niobium are approximately the same in terms of gross value: Nb ₂ O ₅ / Ta ₂ O ₅ = 5 ÷ 20. These deposits are in differentiated massifs of agpaitic nepheline syenites, deposits in metasomatically altered alkaline granitoids, as well as in apogneissic metasomatites of regional fault zones.

Columbite (Fe, Mn) · (Nb, Ta) ₂ O ₆ was the first niobium mineral known to mankind. And this same mineral is the richest element No. 41. Oxides of niobium and tantalum account for up to 80% of the weight of columbite. Much less niobium in pyrochlore (Ca, Na) ₂ (Nb, Ta, Ti) ₂ O ₆ (O, OH, F) and loparite (Na, Ce, Ca) ₂ (Nb, Ti) ₂ O ₆ . In total, more than 100 minerals are known, which include niobium. Significant deposits of such minerals exist in different countries: Brazil, USA, Canada, Norway, Finland, etc.

In Russia there are large reserves of loparite, they are found on the Kola Peninsula. Predicted resources of niobium pentoxide in Russia are concentrated in the Irkutsk region and the Krasnoyarsk Territory and are estimated at 292.6 thousand tons. Russia ranks second after Brazil for this indicator. Russia also ranks second in the world after Brazil in terms of the amount of niobium pentoxide balance reserves. More than 65% of ores are concentrated in Eastern Siberia, about 30% are in the Murmansk region. Niobium ores in Russia are mostly low-grade; the average content of niobium pentoxide in the predicted resources is 0.3-0.9%, in explored reserves - 0.2%.

Brazil is the leader in the extraction and production of niobium by a wide margin. Of the total volume of niobium in concentrates (86.0-88.6 thousand tons of Nb ₂ O ₅ ), Brazil accounts for more than 90% - 81-83 thousand tons. In Canada, 7-9% is produced, in other countries - 1 % or less. Pyrochlore deposits are being developed in Brazil and Canada. Currently, approximately 90% of the world's primary production of niobium is accounted for by its extraction from pyrochlore. About 7.5% of the total primary niobium is extracted as a by-product of the production of tantalum in the processing of columbite.

Russia's share in global tantalum consumption does not exceed 1-2%.

Many methods for processing niobium-tantalum ores and concentrates are known. Previously, basically, two methods of processing loparite concentrate were used, which provided the production of refractory metal oxides, referred to as specialists in perchloric and sulfuric acid technologies. Chlorine technology is described quite fully in the dissertation of M. Petukhov. “Study of the process of chlorination of tantalite-columbite concentrate and the creation of technology for the joint processing of tantalite-columbite and loparite concentrates”, M. “MISiS”, 2010

It was the first to study the process of chlorination of tantalite-columbite concentrate in a melt of an equimolar mixture of potassium and sodium chlorides, and it was established that sodium chloride and concentrate react with the formation of methaniobates and, possibly, sodium metatanthalates and iron chloride in the melt, which helps to increase the speed and degree of chlorination of tantalite-columbite concentrate.

It was shown that the rate and degree of chlorination of the concentrate increases with increasing temperature. The extraction of niobium and tantalum into the condensate is greater than that of other components of tantalite-columbite concentrate and its mixture with loparite.

Direct extraction of tantalum into the condensate of the gas-vapor mixture amounted to 87.5%, niobium - 99.5%. The specific consumption rates of chlorine, pitch coke, argon and electricity are determined.

The chlorine technology of processing loparite concentrate provides the recovery of 93-94% niobium and 86-88% tantalum into technical oxides, 96.5-97% titanium into technical tetrachloride.

However, chlorine technology is very dangerous and harmful to staff and the environment due to the use of large amounts of chlorine, and therefore, from the point of view of environmental safety, it is completely unacceptable for use and has very limited use.

A known method of processing tantalum-niobium concentrates, which relates to the hydrometallurgical processing of ore concentrates. The method includes the decomposition of loparite concentrate at a temperature of 103-105 ° C and a concentration of hydrofluoric acid 38-42% (wt.) To obtain a pulp containing fluorides of titanium, REE, niobium, tantalum and sodium. The pulp is filtered at a temperature of 90-95 ° C with the release of fluorides of niobium and tantalum and at least 58% sodium in terms of Na ₂ O into the fluorotitanium solution and the precipitate containing REE fluorides and residual sodium is separated. The resulting solution is cooled to 18-24 ° C with the separation of the second precipitate of sodium fluorotitanate, after which niobium and tantalum are extracted from the solution by extraction with octanol-1 at a ratio of organic and aqueous phases (1.0 ÷ 1.1): 1. The precipitate of REE fluorides is washed from sodium fluorotitanate with water in one stage at a temperature of 90-95 ° C and T: W = 1: (2.0 ÷ 2.5). The wash solution was separated and evaporated to give an additional precipitate of sodium fluorotitanate. After extraction of niobium and tantalum, the fluorotitanic solution is evaporated and filtered to separate the first precipitate of sodium fluorotitanate from a concentrated solution of fluorotitanic acid, which is directed to the extraction of titanium. The resulting sodium fluorotitanate contains a reduced amount of impurity components of calcium and strontium (RF patent No. 2270265, published February 20, 2006).

This method is not technologically advanced due to its complexity and duration, the use of elevated temperature, which is associated with additional energy costs, as well as due to the relatively low extraction of the amount of niobium and tantalum into the extract in one extraction step. Also, this method of extraction of niobium and tantalum with octacol-1 is not applicable for concentrates with a low titanium content, as in columbite concentrate.

In the abstract of the dissertation for the degree of candidate of technical sciences Baklanova IV “Extraction of niobium and tantalum by octanol in the technology of rare metal raw materials”, (Kola Science Center RAS, Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials named after IV Tananaev, Apatity - 2004), the purpose of which was to develop and justify low-waste technological schemes for obtaining pure compounds of tantalum and niobium by extraction with n-octanol and its isomers during hydrometallurgical processing of rare-metal raw materials, based on extensive research and testing to create extraction technological schemes m niobium- and tantalum-processing solutions with low content of metals as well as for using the new extractants for processing of concentrated solutions of rare metals, recommendations for the individual operations concentrates processing process.

The extraction of niobium and tantalum complexes is largely determined by their state in solutions and the nature of the organic reagent. In industry, two variants of extraction schemes are usually implemented: collective extraction with the separation of niobium and tantalum at the stage of re-extraction and selective (sequential) extraction of niobium and tantalum.

After preparatory operations (crushing, grinding), the opening of the feedstock to achieve the complete transition of niobium and tantalum into the solution is required with a sufficiently large excess of hydrofluoric acid (HF). In technology, it is often necessary to reduce the concentration of HF in the extraction system to improve the separation and separation of niobium and tantalum.

Separation of niobium and tantalum by octanol is realized when the content of sulfuric acid during extraction is about 200 g / l. At a lower concentration of H ₂ SO _{4, the} co-extraction of niobium is significantly lower. However, the degree of tantalum extraction is also reduced, which does not allow its complete extraction to be achieved or requires the implementation of too many equilibrium steps on the extraction cascade. When the content of H ₂ SO _{4 is} more than 200 g / l, the determining factor is the rapid increase in the coextraction of niobium and, accordingly, the deterioration of the separation of rare elements.

The extracts were purified from impurities by treatment with water, acid solutions, and fluoride solutions of these elements.

The niobium and tantalum extract washed from impurities is sent for the re-extraction of niobium with water. It was found that at O: B = 3: 1, about 80% of niobium and less than 20% of tantalum pass into the aqueous phase in one step. In countercurrent mode, the concentration of niobium in a reextract of 300-350 g / l Nb ₂ O ₅ and higher was achieved. Tantalum is readily extracted from the washed extract with water, and octanol is returned to the process. The spent solution after washing the tantalum extract, in order to avoid loss of rare metals, is connected to the initial solution, which is used for the extraction of niobium and tantalum.

According to the author, the implementation of the proposed technological schemes will simplify the production of high-purity compounds of tantalum and niobium in the processing of loparite and columbite-tantalite concentrates and reduce the amount of waste.

However, the disadvantages of the known technical solutions include the relatively low extraction of tantalum and niobium from the initial concentrate, because the parameters of some operations of the processing process are not optimal, as well as the high consumption of expensive hydrofluoric acid, which is very aggressive and requires additional equipment protection, and during the opening process, hydrofluoric acid evaporates.

The closest technical solution to the claimed method is the processing of tantalum-niobium concentrates, described in the manual "Chemical technology of tantalum" (A.A. Kopyrin, N.V. Zots, A.V. Nechaev, Yu.G. Glushchenko, St. Petersburg. : SPbGTI (TU), 2010. - 80 pp.), Which provides information on modern technology for processing columbite concentrates. Currently, tantalite and columbite concentrates are most often opened with hydrofluoric acid. Tantalum and niobium pass into solution in the form of complex acids, the composition of which depends on the concentration of HF. In addition to niobium, tantalum, iron, and manganese, other elements contained in the accompanying minerals of tin, titanium, silicon, and tungsten as part of complex acids are transferred into the solution: H ₂ SnF ₆ , H ₂ TiF ₆ , H ₂ SiF ₆ , H ₂ WF ₈ .

Opening the concentrates with hydrofluoric acid gives solutions that are heavily contaminated with foreign elements, which previously made it difficult to isolate pure tantalum and niobium compounds from them. Effective processing of these solutions became possible with the development of extraction methods for the extraction and separation of tantalum and niobium, as well as their separation from other elements. When hydrofluoric acid is decomposed, the technological scheme contains fewer operations than in the fusion of concentrates with alkaline reagents. In order to intensify the opening of concentrates and to improve the subsequent extraction processing of solutions, it is recommended to use a mixture of hydrofluoric and sulfuric acids.

When the concentrate is opened, niobium and tantalum go into solution. The resulting solution is directed to the extraction extraction and separation of niobium and tantalum.

Collective countercurrent extraction of a solution containing niobium and tantalum by means of octanol-1 and its isomers (otanol-2, 2-ethylhexanol) having similar extraction properties. N-octyl alcohol CH ₃ (CH ₂ ) ₆ CH ₂ OH has a solubility in water of 0.05 wt.%, Specific gravity 0.824 g / cm ³ , melting point -16 ° C, boiling point 195 ° C, flash point 64 ° C; MAC when working with OKL - 10 mg / m ³ .

The separation of niobium and tantalum is carried out by washing the niobium from the extract purified from impurities with a solution of a mineral acid, after which tantalum is re-extracted. Since part of tantalum is also washed along with niobium, usually traces of tantalum are extracted from the niobium-containing aqueous solution.

The obtained reextracts of niobium and tantalum are sent for further processing in order to obtain the corresponding individual compounds.

The disadvantages of the prototype include the fact that in this source it recommends a general technology for processing niobium-tantalum concentrates, therefore, in order to obtain the optimal parameters of individual operations, considerable research is necessary to establish the influence of related factors and increase the degree of extraction of individual elements and reduce the content of impurities in them.

The basis of the present invention was the task to develop a method for processing niobium-tantalum concentrate, in which the opening would be carried out under such conditions as to ensure an increase in the degree of opening of the concentrate and its time to be reduced, a reduction in energy consumption for the process would be achieved, the filterability of the resulting pulp after opening would be improved, yield of marketable products and obtain high-quality niobium and tantalum-containing solutions for further processing, and ensuring safe conditions labor.

The technical result is achieved in that in a known method of processing columbite concentrate, including preparing the concentrate for opening, opening the concentrate with a mixture of sulfuric and hydrofluoric acids, filtering the pulp with separation of cake, which is washed and sent for further processing, collective countercurrent extraction of a solution containing niobium and tantalum octanol, washing the extract, followed by re-extraction of niobium and tantalum, moreover, the niobium re-extract is subjected to additional de-ethanization, then the obtained reextracts are sent for separate processing to the appropriate individual compounds, changes and additions have been made, namely:

- before filtration, the pulp is cooled, and before extraction, the filtrate is mixed with wash water;

- moreover, the washing of the extract is carried out with a mixture of sulfuric and hydrofluoric acids, the optimal concentration;

- the optimal values of the parameters of each operation are selected depending on the composition and concentration of the incoming reagents.

In addition, the opening of the concentrate is carried out at a temperature of 75-85 ° C, with a ratio of T: W = 1: (4.5 ÷ 5.0) in excess of hydrofluoric acid, at a concentration of 230-250 g / l and a concentration of sulfuric acid - 390-410 g / l, and pulp cooling before filtration is carried out to a temperature of 38-45 ° C.

The extraction is carried out continuously in mixing-settling extractors with the ratio O: B = 1: (0.34 ÷ 0.38), the extract is washed with a mixture of hydrofluoric and sulfuric acids, with concentrations of 55-65 g / l and 290-310 g / l accordingly, with the ratio O: B = 1: (0.15 ÷ 0.20), niobium is reextracted with a solution of sulfuric acid with a concentration of 290-310 g / l, and tantalum with softened water, with the ratio O: B = 1 :( 0.52 ÷ 0.70) and O: B = 1: (0.28 ÷ 0.32), respectively, and de-extraction of the niobium reextract is carried out with the ratio O: B = 1: (2.20 ÷ 2.30).

Opening of columbite concentrate in a mixture of sulfuric and hydrofluoric acids allows one to separate cake containing almost all active elements (uranium and thorium), as well as rare-earth metals, and a solution containing target components - niobium and tantalum, already at the first stage of the technological process. The solution obtained after opening the concentrates is radiation-safe.

Cooling the pulp to a temperature of less than 38 ° C reduces its filtration rate; at temperatures over 45 ° C, i.e. above the claimed range, there is a filtration rate of the pulp, but the cake is difficult to separate from the filter cloth.

The use of octanol-1 as an extractant for niobium and tantalum makes it possible to separate niobium and tantalum from "vulgar impurities" at the extraction cascade, as well as to obtain a niobium-containing solution (niobium reextract) with a minimum content of tantalum and impurities at the stage of selective re-extraction of niobium. High purity niobium oxide (≥99.5%) is obtained from this solution by precipitation technology. The tantalum-containing solution (tantalum re-extract) is sent for further processing, the technology of which depends on the required degree of purity of the resulting product.

Re-extraction of niobium from the solution is carried out with sulfuric acid, and not with water, because this allows you to increase the degree of extraction of niobium, and the concentration and O: B ratios should be selected optimal, based on the analysis of test results.

An analysis of the totality of the features of the claimed invention and new parameters for their implementation and the result achieved with this shows that there is a certain causal relationship between them, because they are obtained as a result of research and experimental testing, which were carried out according to the proposed method. The following are the results obtained from these tests.

During autopsy experiments, the concentration of hydrofluoric and sulfuric acids, the temperature, and the T: W ratio in the pulp were controlled, which affect the completeness of opening of the columbite concentrate.

The experimental technique was as follows. In the reactor equipped with a stirrer and a thermocouple, the required amount of the mixture of acids was preliminarily poured, mixed for 2-3 minutes; then gradually weighed a portion of the columbite concentrate.

The temperature was fixed (with an error of ± 3 ° C) after loading and exiting it to the set value, then heating and thermostat were turned on.

The pulp was maintained at a given temperature and constant stirring for the specified time (τ = 8 h). After a predetermined time interval, a sample was taken, filtered, cake on the filter was washed. The filtrate and wash water were returned for the content of valuable components and impurities. The results of experiments on the opening of columbite concentrate are presented in table. one.

Note 1: The degree of extraction of Ta ₂ O ₅ and Nb ₂ O ₅ into the solution was calculated by the content of Ta ₂ O ₅ and Nb ₂ O ₅ in the initial sample concentrate and by the content of Ta ₂ O ₅ and Nb ₂ O ₅ in the filtered solution after opening, washing water and taking into account the sampling during the process.

From the data table. 1, it can be noted that the temperature, concentration and consumption of hydrofluoric acid, as well as the content of up to 390-410 g / l sulfuric acid in the mixture, positively affect the degree of extraction of niobium and tantalum. The smallest extraction of Nb ₂ O ₅ and Ta ₂ O ₅ in the solution was noted in experiments characterized by a concentration of sulfuric acid in the solution of less than 390 g / l, and also by a low temperature of less than 75 ° C.

The temperature of the opening process is also a determining factor for this process. At a temperature of 75-85 ° C, the opening is much more intense than at a temperature of 70 ° C. The concentration of Σ (Nb ₂ O ₅ + Ta ₂ O ₅ ) = 120-130 g / l at 80 ° C is achieved in 8 hours of the opening process. It should also be noted that an increase in the process temperature of more than 75-85 ° C, apparently, is positively related to the degree of extraction of Nb ₂ O ₅ and Ta ₂ O ₅ into the solution, however, at these temperatures additional problems arise with the choice of structural materials for organization an industrial opening process for corrosive media such as a mixture of hydrofluoric and sulfuric acids at temperatures close to 100 ° C. Also, at temperatures above 100 ° C, the pressure of saturated HF vapors above the solution sharply increases, the evaporation rate of HF increases, which increases the consumption of hydrofluoric acid and the load on the gas treatment equipment.

The ratio of T: W in the initial pulp, equal to 1: (4.5 ÷ 5.0), allows to achieve a concentration of Σ (Nb ₂ O ₅ + Ta ₂ O ₅ ) = 120-130 g / l. Changing this ratio in the direction of increasing the liquid phase in the pulp is a very negative factor in the organization of industrial technology for opening the feedstock for the subsequent extraction of niobium and tantalum for the following reasons: the cure of niobium and tantalum in the solution is reduced; during extraction with octanol-1, the so-called "phase inversion" process is possible (the density of the organic phase becomes higher than the density of the aqueous phase); due to an increase in the density and viscosity of the aqueous and organic phases, the likelihood of mechanical entrainment of the dispersed aqueous phase and the organic and dispersed organic phase in the aqueous phase and the like increases.

Impurities such as iron and manganese, which are present in macro amounts in columbite concentrate, are extracted into the solution along with niobium and tantalum.

The influence of the temperature formed during the opening of the pulp on the rate of its filtration was studied as follows.

After opening, the pulp was cooled by natural heat exchange with the environment (without forced cooling) to a certain temperature. Then the temperature was recorded (with an error of ± 3 ° C); after it exited to the set value, heating and thermostat were turned on; thus, the pulp was kept under stirring for 1 h. After the pulp was kept, it was filtered on a vacuum filter (on KS-44 filter cloth) and the technological properties of the cake were fixed.

Data on the study of the process of filtering the pulp after opening the concentrate are presented in table. 2.

From the data table. 2 it can be noted that the pulp, when filtering in the temperature range of 70-85 ° C, has a high filtration rate of 0.10 m ³ / (m ² · h), however, the precipitate is difficult to separate from the filter cloth. This circumstance leads to additional labor costs for servicing the filtration equipment during pulp filtration operations, as well as to an increased consumption of filter cloth. When filtering the pulp, cooled to a temperature of 38-45 ° C, has a fairly high filtration rate of 0.06 m ³ / (m ² · h), and is also easily separated from the filter cloth. Cooling the pulp to 20-25 ° C leads to a sharp decrease in the rate of filtration of the pulp.

In order to simulate the washing processes, as well as selecting the optimal composition of the washing solution, a series of experiments was carried out in a batch mode.

The experiments were carried out as follows: a predetermined amount of aqueous (initial solution for extraction) and organic phases (extractant — octanol-1) were poured into a separatory funnel with a stirrer.

Then the mixer was turned on at the optimum speed (without the formation of very thin, non-stratified emulsions) and the extraction process was carried out. After 3 minutes, the mixer turned off.

After complete delamination and clarification, the phases were separated using the lower tap of the separatory funnel (discharge of the aqueous phase) and samples of the aqueous phase were taken for analysis. The volumes of the aqueous and organic phases and their density were measured.

Conducted 1 contact of the extractant with the initial solution, the composition of which is given in table. 3, then the organic phase was divided into 5 equal parts and contacted with washing solutions of various compositions at the same O: B ratio.

The effectiveness of the washing process was judged by the concentration of impurities in the organic phase after contacting with the washing solution.

Data analysis table. 3 shows that a solution of 60 g / l HF + 300 g / l H ₂ SO ₄ has the highest selectivity with respect to Al, Ca, Ti, Zr, W impurities. A decrease in the concentration of hydrofluoric and sulfuric acids in the washing solution to 50 and 280 g / l leads to a decrease in the degree of washing of the extract (increasing the concentration of impurities in the extract after washing) from impurities. An increase in the concentration of hydrofluoric and sulfuric acids in the washing solution to 70 and 320 g / l leads to an additional consumption of sulfuric acid and does not significantly affect the degree of washing of the extract from impurities.

In order to simulate the process of re-extraction of niobium, as well as to select the optimal composition of the re-extracting niobium solution, a series of experiments was carried out in a batch mode.

The experiments were carried out as follows: a predetermined amount of aqueous (initial solution for extraction) and organic phases (extractant — octanol-1) were poured into a separatory funnel with a stirrer.

Then the mixer was turned on at the optimum speed (without the formation of very thin, non-stratified emulsions) and the extraction process was carried out. After 3 minutes, the mixer turned off.

After complete delamination and clarification, the phases were separated using the lower tap of the separatory funnel (discharge of the aqueous phase) and samples of the aqueous phase were taken for analysis. The volumes of the aqueous and organic phases were measured.

Conducted 1 contact of the extractant with the initial solution, the composition of which is given in table. 4, then the organic phase was divided into 3 equal parts and contacted with stripping solutions of various compositions at the same O: B ratio.

The effectiveness of the re-extraction of niobium was judged by the separation coefficient β _Ta-Nb .

The results of a study on the re-extraction of niobium in periodic mode are given in table. four.

Data analysis table. 4 shows that the highest selectivity (separation coefficient) with respect to Nb ₂ O ₅ has a solution of sulfuric acid H ₂ SO ₄ - 300 g / l. A decrease in the concentration of sulfuric acid in the stripping solution to 250 g / l leads to a decrease in the selectivity of the solution with respect to Nb ₂ O ₅ , which may require a significant increase in the number of stages of the extraction cascade. An increase in the concentration of sulfuric acid in the stripping solution to 350 g / l leads to an additional consumption of sulfuric acid and does not significantly affect the selectivity of the stripping solution.

Below are the results of experiments on the selection of optimal parameters for the continuous extraction process, washing the extract, reextracting niobium and tantalum, as well as de-energizing the reextract niobium.

The extraction separation of niobium and tantalum and their purification from impurities was organized as follows.

The continuous countercurrent extraction cascade involved 45 working stages on countercurrent mixing-settling extractors. In the process of continuous testing of the extraction separation of niobium and tantalum, a search was carried out for optimal extraction redistribution modes.

A series of studies within this phase was aimed at finding the optimal modes for obtaining a niobium reextract and tantalum reextract of the required quality.

The number of steps in the contours of the cascade:

- the total number of working steps in the cascade n = 45

- the number of steps in the extraction part n = 10

- the number of steps in the washing part n = 6

- the number of steps in the de-energization circuit n = 6

- the number of steps on the re-extraction of niobium n = 11

- the number of steps on the re-extraction of tantalum n = 9

- the number of sludge chambers of the organic and aqueous phases n = 3

Working solutions per cascade:

1. Stock solution, g / l:

Ta ₂ O ₅ - 10.1; Nb ₂ O ₅ - 126.3; Mn - 3.0; Fe - 25.1; Al - 0.85; Ca 0.2; Ti - 0.9; Zr 0.14; Si 9.37; F - 190.6; the density of the solution is ρ = 1.395 g / l.

2. Wash solution: H ₂ SO ₄ - 300 g / l + HF-60 g / l.

3. Reextracting solution for niobium: H ₂ SO ₄ - 300 g / l.

4. Reextracting solution for tantalum: deionized water.

5. The extractant is circulating octanol-1 (ρ = 0.825 g / l).

The efficiency of the extraction cascade was judged by the concentrations of elements with raffinate, niobium reextract, tantalum reextract, and the organic phase after tantalum reextraction. Samples were taken after the extraction cascade was brought into equilibrium after 36 hours of continuous operation of the extraction cascade.

The results of the extraction cascade are presented in table. 5.

Data analysis table. 5 shows that in the optimal mode (experiment 4), the re-extract of niobium contains impurities of Ta ₂ O ₅ less than 0.1 g / l, which allows to obtain niobium hydroxide of the required quality.

The de-decanting circuit has been shown to be effective - niobium reextract when working with the de-decanting circuit does not contain Ta ₂ O ₅ .

The concentration of Nb ₂ O ₅ in the tantalum reextract is 0.02 g / l with a minimum amount of vulgar impurities. From this solution it is possible to obtain tantalum hydroxide of the required quality.

The organic phase after re-extraction of tantalum practically does not contain Ta ₂ O ₅ and Nb ₂ O ₅ (less than 0.1 g / l); This mode of re-extraction of niobium and tantalum allows you to completely regenerate the organic phase for reuse in the extraction process.

With this ratio of O: B phases, almost complete extraction of Ta ₂ O ₅ and Nb ₂ O ₅ from the initial solution is also achieved by extraction; the content of Ta ₂ O ₅ and Nb ₂ O ₅ in the raffinate during steady state cascade operation does not exceed 0.1 g / l. The organic phase is completely regenerated; the content of Ta ₂ O ₅ and Nb ₂ O ₅ in the organic phase after re-extraction of tantalum is less than 0.1 g / l, which can be considered a satisfactory result.

For a better understanding of the claimed technical solution, we consider its implementation on the example of the processing of columbite concentrate with optimal parameters for redistribution operations.

The flow chart is shown in FIG. 1. It is presented in the form of separate blocks corresponding to the name of the operation. The blocks also indicate the parameters of each operation, and they are located in the sequence of implementation of the claimed invention. The technological scheme does not need additional explanation, because all connections between the blocks and the direction of the reagents received for each operation are indicated by arrows, which indicate their name and information necessary for understanding the implementation of each operation.

In FIG. Figure 2 shows a more detailed diagram of the extraction cascade, which shows the location of the main equipment - mixing-settling extractors and their number in each operation: extraction, washing, re-extraction of niobium and tantalum, as well as de-energizing re-extract of niobium.

The symbols shown in FIG. 2, mean: N-1 / 1-7 - pumps that transport working solutions in each operation; EK-1 / 1-45 - the number of extractors used in all the above operations, including each of them; E-1 / 1-9 - containers for the source and final products obtained in each operation, and their purpose is clear from the names indicated on each container; FTI - flow control devices (flow meter).

The crushed columbite concentrate containing niobium and tantalum was sent to production, where it was opened after preparation.

Columbite concentrate was opened in an autopsy reactor equipped with a mixing device, fittings for supplying a heating agent, and fittings for connecting to an aspiration system and sampling devices allowing sampling resulting from opening the pulps. For opening, a mixture of hydrofluoric and sulfuric acids with a concentration in solution of 240 and 400 g / l, respectively, was loaded into the reactor and mixed for 2-3 minutes. Then, the columbite concentrate was portionwise loaded into the reactor with constant stirring to a ratio and the reaction mixture was heated to a temperature of 80 ° C.

The pulp was kept at a given temperature, constant stirring for the specified time (τ = 8 h). After a predetermined time interval, a sample was taken, filtered and washed. The filtrate and wash water were returned for analysis of the content of valuable components and impurities.

After completion of the autopsy process, the reaction pulp was naturally cooled to a temperature of 42-45 ° C and then kept under stirring for 1 h.

Aspiration gases containing hydrogen fluoride vapors and traces of silicon fluoride were sent for gas purification. Purified air was released into the atmosphere.

The reaction pulp from the opening reactor was discharged into a suspension receiver connected to a vacuum system.

After filtering the reaction pulp and draining the filtrate into an intermediate tank, the cake was washed on a filter partition.

The filtrate and wash water were combined in an intermediate tank. The washed cake was sent for processing.

The solution obtained after combining the filtrate with washings after the washing of the precipitate, containing the main amount of niobium and tantalum with a small amount of impurities, was the initial solution for the extraction separation process on the extraction cascade (see Fig. 2).

The extraction cascade consisted of 45 mixer-settler extractors with mechanical stirring.

The extraction cascade consisted of the following circuits (stages):

- extraction part - 10 extractors;

- washing part - 6 extractors;

- contouring system - 6 extractors;

- re-extraction of niobium - 11 extractors;

- Re-extraction of tantalum - 9 extractors.

The following solutions were used for the extraction cascade:

- extractant - 100% octanol-1;

- stock solution for the extraction cascade;

- washing solution -300 g / l H ₂ SO ₄ +60 g / l HF;

- reextracting niobium solution - 300 g / l H ₂ SO ₄ ;

- reextracting tantalum solution - deionized water.

The ratio of the flows (flow rate) of the organic and aqueous phases α = Vо / Vв in the circuits of the extraction cascade is very important variable, i.e. controlled and adjustable parameter depending on various factors (composition of the initial solution, the value of the separation coefficients, etc.), but for a specific process and real conditions there is a basic ratio that can vary slightly in one direction or another, and which is taken at startup extraction cascade (indicated on the block diagram of Fig. 1).

For the extraction cascade, the following basic ratios of the organic and aqueous phases are adopted:

- extraction part: O: B = 1: (0.34 ÷ 0.38);

- washing part: O: B = 1: (0.15 ÷ 0.20);

- de-energization circuit: O: B = 1: (2.20 ÷ 2.30);

- re-extraction of niobium: O: B = 1: (0.62 ÷ 0.70);

- tantalum reextraction: O: B = 1: (0.28 ÷ 0.32).

The initial solution from the vessel E-3 for extraction separation (see Fig. 2), containing ~ 120-130 g / l Σ (Nb ₂ O ₅ + Ta ₂ O ₅ ), 25-30 g / l (Fe + Mn) as well as up to 5-7 g / l of vulgar impurities (W, Ti, Zr, Al, Si, Ca, etc.), is pumped by the N-1 pump to the head chamber of the extraction cascade.

The extractant (100% octanol-1 reverse) is supplied countercurrent to the initial solution. The organic phase after the de-decanting circuit, containing up to 60 g / l ∑ (Nb ₂ O ₅ + Ta ₂ O ₅ ), is also fed to the extraction part of the cascade.

The initial solution, moving along the extraction circuit of the cascade, is depleted in Nb ₂ O ₅ and Ta ₂ O ₅ , because Nb ₂ O ₅ and Ta ₂ O ₅ pass into the organic phase and merge from the last chamber by gravity in the form of a raffinate (capacity E-1) with a content of ∑ (Nb ₂ O ₅ + Ta ₂ O ₅ ) of less than 0.1 g / l and then goes to the disposal of fluoride-sulfate effluents. Impurities that were in the initial solution are removed with the raffinate.

A washing solution containing a mixture of hydrofluoric and sulfuric acids with a concentration of 60 and 300 g / l, respectively, is supplied countercurrent to the organic phase in the washing circuit of the extraction cascade.

Saturated ∑ (Nb ₂ O ₅ + Ta ₂ O ₅ ) extractant after the extraction circuit enters the washing circuit. In addition to the sum ∑ (Nb ₂ O ₅ + Ta ₂ O ₅ ), impurities (W, Zr, Al, Ca, etc.) also pass to the organic phase to a different degree, therefore, upon contact with the washing solution, these impurities are displaced from the organic phase to the aqueous. As a result, at the outlet of the washing circuit, the extractant will be saturated in ∑ (Nb ₂ O ₅ + Ta ₂ O ₅ ), and the washing solution, passing through the washing circuit and simultaneously removing a certain amount of Nb ₂ O ₅ and Ta ₂ O ₅ , will be attached to the initial solution for extraction.

The washed extractant after the washing circuit enters the circuit for selective re-extraction of niobium. Reextracting niobium solution containing 300 g / l of sulfuric acid is supplied countercurrent to the washed extractant. Countercurrently passing the washed extract, reextracted solution "removes" the organic phase with Nb ₂ O ₅ and Ta ₂ O ₅ (Nb ₂ O ₅ to a much greater extent.

Further, the aqueous phase (re-extract of niobium contaminated with tantalum) after re-extraction of niobium enters the de-exhaustion circuit. At the same time, an extractant (100% octanol-1 reverse) is supplied in countercurrent reextract with niobium. Niobium reextract, moving along the reextraction circuit with countercurrent extractant, is depleted in Nb ₂ O ₅ and Ta ₂ O ₅ , because Nb ₂ O ₅ and Ta ₂ O ₅ pass into the organic phase, and merge by gravity in the form of a pure niobium reextract with a Ta ₂ O ₅ content of less than 0.1 g / L. Niobium re-extract, as it accumulates, is directed to the production of individual niobium compounds. The organic phase after the de-decanting circuit, containing Σ (Nb ₂ O ₅ + Ta ₂ O ₅ ), is gravity drained into an intermediate tank.

The niobium-depleted organic phase enters the tantalum re-extraction circuit. In this case, a counter-extracting tantalum solution is supplied to a countercurrent extractant. Having passed the countercurrent circuit of tantalum reextraction, the stripping solution “removes” Ta ₂ O ₅ from the organic phase and merges by gravity in the form of a tantalum reextract, which is sent for further processing to its compounds.

As a result, at least 96% Nb ₂ O ₅ and Ta ₂ O _{5 are} recovered from the columbite concentrate.

The advantages of the proposed method is that the proposed technology is effective, does not cause difficulties in its implementation and is relatively safe for staff and equipment life.

Currently, the laboratory research phase has been completed and the results obtained will be used in pilot studies at pilot plants, which are supposed to be implemented in 2015.

Claims (6)

1. A method of processing columbite concentrate, including preparing the concentrate for opening, opening the concentrate with a mixture of sulfuric and hydrofluoric acids, filtering the pulp to separate the cake from the filtrate in the form of a solution containing tantalum and niobium, washing the cake with rinsing water, sending the cake for further processing, collective countercurrent extraction of a solution containing niobium and tantalum, octanol, washing the extract, subsequent selective reextraction of niobium and tantalum to obtain a niobium reextract and reextract and tantalum, wherein the niobium reextract is subjected to additional de-ethanization, then the obtained reextracts are sent for separate processing to the corresponding individual compounds, characterized in that the pulp is cooled before filtration, and the filtrate is mixed with washings before extraction, and the extract is washed with a mixture of sulfuric and hydrofluoric acids . 2. The method according to p. 1, characterized in that the opening of the raw material is carried out at a temperature of 75-85 ° C, with the ratio Τ: W = 1: (4.5-5.0) in excess of hydrofluoric acid, at a concentration of 230- 250 g / l and sulfuric acid concentration - 390-410 g / l. 3. The method according to p. 1, characterized in that the cooling of the pulp before filtering is carried out to a temperature of 38-45 ° C. 4. The method according to p. 1, characterized in that the extraction is carried out continuously in a mixing-settling extractors with a ratio of O: B = 1: (0.34-0.38), and the washing of the extract is carried out with a mixture of hydrofluoric and sulfuric acids having concentrations 55-65 g / l and 290-310 g / l, respectively, with the ratio O: B = 1: (0.15-0.20). 5. The method according to p. 1, characterized in that the re-extraction of niobium is carried out with a solution of sulfuric acid with a concentration of 290-310 g / l, and tantalum with softened water, with a ratio of O: B = 1: (0.62-0.70) and O: B = 1: (0.28-0.32), respectively. 6. The method according to p. 1, characterized in that the de-extraction of the niobium reextract is carried out with a ratio of O: B = 1: (2.20-2.30).

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