RU2176676C1 - Method of processing vanadium-containing middlings - Google Patents

Abstract

FIELD: metallurgy; production of commercial vanadium pentoxide from various middlings. SUBSTANCE: method includes treatment of vanadium-containing middlings with alkaline solution, separation of insoluble residue from NaVO₃ solution and washing it, combining filtrate and alkaline industrial water, introducing ammonium-containing inorganic compound, for example NH₄Cl and/or NH₄NO₃,, separation of ammonium metavanadate from solution and its crystallization, filtration of suspension, separation of NH₄VO₃ sediment from mother liquor, flushing, drying and calcinating the sediment, thus obtaining commercial vanadium pentoxide. NaOH solution at concentration of 40120 g/cu.dm is used as alkaline reagent; sodium hypochlorite is preliminarily introduced into alkaline reagent to obtain concentration of NaClO from 5 to 25 g/cu.dm and treatment is conducted at mole ratio of NaOH:NaClO = 1: (0.05-0.2) at L:S =(8- 12):1 for 0.5-2 h at 60-90 C. EFFECT: increased extraction of vanadium. 3 ex

Description

The invention relates to the field of metallurgy and can be used, in particular, at the enterprises of ferrous and non-ferrous metallurgy to obtain vanadium pentoxide from various intermediate products containing 50-95% V ₂ O ₅ and impurities of oxides Fe, Cr, Mn, Al, Si, Mg , Ca and others, for example from technical vanadium pentoxide.

Known (Non-ferrous metallurgy, 1976, N 11, S. 29-30) a method for processing vanadium-containing intermediate products of technical vanadium oxytrichloride. According to this method, technical oxytrichloride is poured into a 10% solution of ammonia or sodium hydroxide, the pulp is filtered, the titanium cake is separated from the solution from which ammonium metavanadate is isolated, the latter is washed, dried and calcined at 550 ^° C to obtain vanadium pentoxide.

 The reasons that impede the achievement of the following technical result when using the known method include the formation of large quantities of vanadium-containing production waste: titanium cake; sewage - mother liquors and promoters of ammonium metavanadate.

Of the known analogues, the closest in technical essence and the achieved result to the proposed method is a known method of processing vanadium-containing intermediate products - technical V ₂ O ₅ to produce commercial vanadium pentoxide (Non-ferrous metallurgy, 1995, N 7-8, p. 33-37), which selected as a prototype.

According to the prototype method, vanadium-containing intermediate products (technical V ₂ O ₅ containing impurities of oxides Fe, Mn, Cr, Si, Mg, Ca, etc.) are treated, mainly at elevated temperature, with an alkaline reagent - a solution of sodium hydroxide or carbonate, an insoluble residue (oxyhydrates and metal oxides of impurities) are separated from a solution of sodium metavanadate - NaVO ₃ , which is treated with an ammonium-containing inorganic compound (NH ₄ Cl, NH ₄ NO ₃ and others), the solid phase released from the solution is ammonium metavanadate (NH ₄ VO ₃₎ - separated - filtration of the mother liquor, washed, dried and calcined, to produce vanadium pentoxide V ₂ O ₅ according to the quality requirements of the specification.

 The reasons that impede the achievement of the technical result indicated below include the high content of vanadium in the secondary production waste — in the insoluble residue — after separation of the sodium metavanadate solution.

The claimed technical solution is aimed at solving the problem of increasing the degree of extraction of vanadium and reducing its losses with secondary production waste. The technical result that can be obtained by carrying out the claimed invention is to increase the degree of vanadium separation from the feedstock into a NaVO ₃ solution, which is formed by processing the initial technical V ₂ O _{5 with an} alkaline solution of sodium hypochlorite, and, as a result, a decrease in the content of vanadium in the secondary production waste - insoluble residue after separation of NaVO ₃ solution.

The specified technical result in the implementation of the invention is achieved by the fact that in the known method of processing vanadium-containing industrial products, including their treatment with an alkaline reagent, filtering the pulp, separating the precipitate of metal oxyhydrates from impurities from the sodium metavanadate solution, treating the resulting solution with an ammonium-containing inorganic compound, precipitation and crystallization of ammonium metavanadate filtering the suspension, separating the mother liquor from the precipitate of ammonium metavanadate, washing the precipitate ka, its drying and calcination to obtain commercial vanadium pentoxide, according to the invention, an NaOH solution with a concentration of 40-120 g / dm ^{3 is used} as an alkaline reagent, sodium hypochlorite is preliminarily added to the alkaline reagent to reach a concentration of 5-25 g / dm ³ NaClO and processing are carried out at a molar ratio of NaOH: NaClO = 1: (0.05-0.2) at W: T = (8-12): 1 for 0.5-2 hours at 60-90 ^o C.

 Ceteris paribus, the proposed method, characterized by new methods of performing actions and a new order of performing actions, using certain substances, without which it is impossible to implement the method itself, with new modes and parameters of the process, provides a technical result in the implementation of the claimed invention.

 Checking the patentability of the claimed invention shows that it corresponds to the inventive step, as it should not be obvious to specialists.

The analysis of the prior art indicates that in the book, journal and patent literature there is no information on obtaining vanadium pentoxide from vanadium-containing intermediate products (50-95% V ₂ O ₅ ) by treating the initial intermediate products with an alkaline solution of sodium hypochlorite: solution (40-120) g / dm ³ NaOH + (5-25) g / dm ³ NaClO at a molar ratio of NaOH: NaClO = 1: (0.05-0.2); with W: T = (8:12): 1; for 0.5-2 hours at 60-90 ^o C; filtering the pulp, washing the insoluble residue, precipitating from the resulting solution and washing with NH ₄ VO ₃ , filtering the suspension, washing, drying and calcining NH ₄ VO ₃ to obtain marketable V ₂ O ₅ .

An analysis of the totality of the features of the claimed invention and the result achieved at the same time shows that there is a definite causal relationship between them, expressed in the fact that the implementation of the process of processing vanadium-containing industrial products of technogenic raw materials (50-95% V ₂ O ₅ ) in strictly defined above conditions , modes and parameters of the process (NaOH concentration, NaClO, their ratio, G: T, temperature, time, etc.) enhances the recovery rate V ₂ O ₅ of the middlings into marketable products, reduced e losses V ₂ O ₅ with the secondary waste production (insoluble residue). In violation of the above process modes, sequence of actions, etc. the above technical result is not achieved.

 It should be noted that the established causal relationship does not explicitly follow for specialists and does not follow from the literature on the chemistry and technology of vanadium and its compounds.

 Information confirming the implementation of the invention with obtaining the above technical result, as well as a comparison of the effectiveness of the known (prototype) and the proposed technical solutions are given in the examples.

 Example 1 (by a known prototype method).

One kilogram of vanadium-containing intermediate is a technical V ₂ O ₅ produced by OAO Chusovskoy Metallurgical Plant, containing% (by weight): 50.2 V (IV and V); 1.4 Fe ₂ O ₃ ; 2.4 MnO ₂ ; 0.26 SiO ₂ and TiO ₂ impurities; Cr ₂ O ₃ ; Al ₂ O ₃ ; MgO; CuO and others, were treated at 80 ± 5 ^o C with a solution of sodium hydroxide (100 g / DM ³ ) at W: T = 10: 1 for 1 hour. The insoluble residue (oxides of Fe, Ti, Si, Cr, Mn, Ca, Mg, etc.) was separated from the solution, washed, dried, and calcined.

2.2 kg of NH ₄ Cl were added to the sodium metavanadate-NaVO ₃ solution obtained after separation of the insoluble residue, kept for 3 hours and filtered. The solid phase which precipitated in this case, the precipitate of ammonium metavanadate NH ₄ VO _{3, was} washed on the filter with a solution of 10 g / dm ³ NH ₄ Cl, then with water. The washed precipitate was dried at 100 ± 5 ^o C and calcined at 550 ± 10 ^o C to constant weight (5 ± 1 h).

Under these conditions, the following results were obtained:
- extraction of vanadium from the original technical V ₂ O ₂ in the filtrate solution after separation of the insoluble residue and its washing - 74%;
- end-to-end vanadium extraction in commercial products - 72.0%;
- the content of V ₂ O ₅ in commercial products is 97.0-98.8%, which meets the requirements of technical specifications for V ₂ O ₅ qualifications VNO-1 and VNO-2;
- loss of vanadium with secondary production waste - insoluble residue - 26%;
- "yield" of wet (60%) insoluble residue to be disposed of in the sludge disposal site - 600 g / kg (kg / t) of the initial vanadium-containing intermediate products - technical V ₂ O ₅ ;
- the vanadium content in the insoluble residue is 34.4% (61.2% V ₂ O ₅ ), calculated on the dry calcined product.

Thus, the known method allows to obtain - at relatively high technological indicators - from vanadium intermediates marketable V ₂ O ₅ , for all normalized impurities corresponding to the requirements of existing specifications.

However, in the processing of the original vanadium raw materials (technical V ₂ O ₅ , intermediates) by a known method, a significant amount of secondary production waste is produced — an unreusable vanadium-containing insoluble residue. In particular, up to 500 kg of such waste is generated per 1 ton of technical V ₂ O ₅ (≈ 90% V ₂ O ₅ ). The extraction of vanadium from these wastes by known methods and methods described in the literature seems to be very problematic, and therefore these wastes must be disposed of in slurry fields, which inevitably entails secondary environmental pollution - due to dust removal, partial erosion by rain and ground waters, etc.

 Example 2 (by the proposed method).

For the experiments used samples of technical V ₂ O ₅ , the composition of which is shown in example 1. To obtain objective data on the comparative effectiveness of the known and proposed methods, all experiments were carried out under conditions identical to the conditions of the experiments according to the known method, except for the leaching operation (processing of the initial vanadium industrial products with an alkaline reagent).

In particular, 1 kg of technical V ₂ O _{5 was} treated at 80 ^o C for 1 hour (W: T = 10) with an alkaline solution (100 g / dm ³ NaOH), into which sodium hypochlorite was previously introduced until a NaClO concentration of 20 g / dm ³ ; molar ratio of NaOH: NaClO ≅ 1: 0.1; the resulting pulp was filtered, the filter cake was washed first with 2 volumes of alkali (20 g / dm ³ ), then with water; the washed insoluble residue was weighed, dried (100 ± 5 ^o C) and calcined at 550 ± 1 ^o C (to constant weight), weighed and analyzed for vanadium and impurity metals. NH ₄ Cl was introduced into the filtrate solution of sodium metavanadate (NaVO ₃ ), held for 3 hours, the solid phase precipitated - the NH ₄ VO ₃ precipitate was separated from the mother liquor by filtration on a laboratory suction filter and washed first with a diluted NH ₄ Cl solution (10 g / dm), then with water, the washed precipitate NH ₄ VO _{3 was} dried (≈ 100 ± 5 ^o C), calcined at 550 ± 10 ^o C for 5 hours (to constant weight), weighed and analyzed for vanadium and all regulated ( according to TU) impurities.

Under these conditions, the following results were obtained by implementing the specified method in optimal conditions:
- the degree of extraction of vanadium from the original technical V ₂ O ₅ into the solution after separation and washing of the insoluble residue - 89% (in the known method - 74%);
- loss of vanadium with secondary production waste with an insoluble residue - 11% (in the known method - 26%);
- the through degree of extraction of vanadium from technical V ₂ O ₅ in commercial products - 87% (by the known method - 72%);
- the content of V ₂ O ₅ in commercial products was (for various experiments) 97.0 - 99.0%, which meets the requirements of technical specifications for V ₂ O ₅ qualifications VNO-1 and VNO-2; the content of regulated impurities (Fe, Si, Mn, Cr, S, P, As, ∑Na, R), SPP and HKO also meets the requirements of TU.

 Thus, the proposed method in comparison with the known allows 15% to increase the degree of extraction of vanadium from the initial intermediates in commercial products; accordingly, irrevocable losses of vanadium are reduced, the amount of secondary vanadium-containing waste products is reduced, and the environmental situation is significantly improved.

 Example 3 (by the proposed method).

 To search and justify the optimal modes and process parameters, several series of experiments were carried out in which the leaching conditions, that is, the processing conditions of the initial vanadium-containing intermediate products with alkaline reagents, were changed. In particular, the ratio W: T, the temperature and time of leaching, the concentration of NaOH solution, the amount of alkali, sodium hypochlorite introduced into the solution, and its initial (before leaching) concentration in the solution, the ratio of NaOH and NaClO in the initial solution before leaching were changed.

For experiments, we used a sample of technological V ₂ O ₅ , the composition of which is shown in example 1 and used in the experiment described in example 2.

The processing operations of the obtained solutions of sodium metavanadate with an ammonium-containing inorganic compound — NH ₄ Cl, crystallization of NH ₄ VO ₃ , washing, drying and calcining were carried out in the same way as described in examples 1 and 2.

The results of the experiments showed that preliminary introduction into the alkaline solution (40-120 g / dm ³ NaOH) of sodium hypochlorite in an amount providing its concentration in the solution of 5-25 g / dm ³ and a molar ratio of NaOH: NaClO = 1: (0.05 -0.2), provides, ceteris paribus (NaOH concentration, W: T, temperature of solutions and leaching time), increasing the degree of extraction of vanadium from the original vanadium intermediate products (technical V ₂ O ₅ ) in a NaVO ₃ solution from 65-75 % by a known method up to 88-91%; accordingly, the amount of secondary production waste (insoluble residue) decreases - by 2.5-4 times and the loss of vanadium; at the same time, the unit productivity of the equipment in the technological cycle increases.

An increase in the concentration of sodium hypochlorite in the system and an increase in its amount (increase in the ratio of NaOH: NaClO) is impractical because this leads to a number of negative consequences at the subsequent stages of processing NaVO ₃ solutions, in particular, when NaVO ₃ containing excess (unreacted part of NaClO) sodium hypochlorite, ammonium-containing inorganic compounds - NH ₄ Cl is introduced into the solution, it is possible that Cl ₂ and ClO ₂ and the formation of explosive mixtures.

 At a lower (than optimal) concentration and amount of NaClO, the effect of increasing the degree of extraction of vanadium from the solid phase into the solution drops sharply.

 In addition, the use of hypochlorites of other metals instead of sodium hypochlorite, for example calcium hypochlorite (i.e., hypochlorite pulp formed during the purification of exhaust gases from chlorine), leads to a decrease in the degree of vanadium recovery compared to the known method, an increase in vanadium losses and an increase in the amount of waste production.

The introduction of sodium hypochlorite in an alkaline solution before leaching is a necessary, but still not sufficient condition to achieve a technical result according to the proposed method: to increase the degree of extraction of vanadium from the original vanadium products (technical V ₂ O ₅ ) into the solution and then into the marketable V ₂ O ₅ ( 97.0-99.0% V ₂ O ₅ ) it is also necessary to observe other optimal leaching conditions: W: T = (8-12): 1; temperature 60-90 ^o C; leaching time 0.5-2 hours; initial concentration of an alkaline solution of 40-120 g / dm ³ NaOH. If these conditions are not met, the technical result of the proposed method is not achieved.

Thus, the developed method provides an increase in the degree of vanadium extraction into commercial products, a decrease in the amount of secondary production waste, and a reduction in vanadium losses during the selective extraction of vanadium from industrial products (for example, technical V ₂ O ₅ ) containing, in addition to vanadium, impurities of oxides of other elements. At the same time, the target product, vanadium pentoxide, satisfies all existing technical specifications in terms of quality, and the degree of vanadium extraction from the feedstock into commercial products is significantly higher than in previously known methods.

Claims (1)

A method of processing vanadium-containing industrial products of production, including their treatment with an alkaline reagent, filtering the pulp, separating the precipitate of metal oxyhydrates from sodium metavanadate solution, treating the resulting solution with an ammonium-containing inorganic compound, precipitating and crystallizing ammonium metavanadate, filtering the suspension, separating the mother liquor from the ammonia metavanadate, washing the precipitate, drying and calcining it to obtain commercial vanadium pentoxide, characterized in that as The alkaline reagent uses a solution of NaOH with a concentration of 40-120 g / dm ³ , sodium hypochlorite is pre-introduced into the alkaline reagent to achieve a concentration of 5-25 g / dm ³ NaClO and the treatment is carried out at a molar ratio of NaOH: NaClO = 1: (0.05- 0.2) at W: T = (8-12): 1 for 0.5-2 hours at 60-90 ^o C.