RU2075526C1 - Method of recovery of metals from metal-containing spent catalysts based on oxides of aluminium and/or silicon - Google Patents

Abstract

FIELD: metallurgy, methods of recovery of metals from metal-containing spent catalysts based on oxides of aluminium and/or silicon including their processing by heating. SUBSTANCE: processing is carried out by melting of catalysts in mixture with lime fluxes and/or alumina with use of plasma-arc heating at temperature of 1600-1650 C with supply of carbon-containing reducer in the amount of 0.06-0.08 of mass of initial material, and iron in the amount of not less than 0.15 of the initial material with subsequent blowing of obtained melt with neutral gas with specific intensity of blowing of 0.2-0.4 cu.m/t.min. EFFECT: higher efficiency. 2 tbl

Description

 The invention relates to methods for extracting metals from metal-containing catalysts, representing a porous insoluble carrier (aluminum oxide and (or) silicon), with a metal deposited on it in the form of a thin film covering the surface of the catalyst base, and can be used in the chemical industry, and in metallurgy.

 Known hydrometallurgical methods for the extraction of metals from metal-containing spent catalysts, including the treatment of the catalyst with nitrogen oxides in the presence of water (ed. St. USSR N 778752, IPC B 01 D 53/02) or a urea solution followed by treatment with nitrogen oxides in the presence of water (ed. St. USSR N 1114701, IPC C 22 B 71/00).

 The disadvantages of the known methods are the lack of integrated processing of spent catalysts, low metal recovery, high cost of the obtained metal, the presence of environmental dirty production effluents and waste in the form of a contaminated catalyst base.

 Meanwhile, the oxide base of the catalyst is a valuable raw material for the production of high-grade cement.

 Closest to the claimed technical solution is the adopted as a prototype method for the extraction of metals from spent catalysts, including processing by heating, for example, sodium chloride and water vapor (Biswas RK Warihava M, Janiguohi M. "Hydrometallurgy", 1985, 14, N 2, 219-230; RJ "Chemistry", 1986, N 4L223).

 The main disadvantages of this method also include low metal recovery, the lack of the possibility of the integrated use of spent catalysts, the presence of large quantities of solutions to be neutralized due to the high concentrations of molybdenum, chlorine and carcinogenic cobalt contained in them. The method is not economically viable.

 The invention is aimed at solving the problem of complex processing of metal-containing spent catalysts made on the basis of aluminum oxides and (or) silicon, which allows to achieve high levels of extraction of valuable components, resulting in valuable grades of high-quality mortars (high-alumina cements, fireclay), to ensure environmental requirements to the process in modern conditions.

The technical result noted above is achieved by the fact that in the known method for extracting metals from metal-containing spent catalysts based on aluminum and (or) silicon oxides, including processing them by heating, according to the present invention, the processing is carried out by melting the catalysts in a mixture with lime fluxes and (or) alumina using plasma-arc heating at a temperature of 1600-1650 ^o C with the supply of a carbon-containing reducing agent in the amount of 0.06-0.08 from the weight of the starting material and iron in the amount of n e less than 0.15 by weight of the starting material, followed by purging the obtained melt with neutral gas with a specific intensity of the blast of 0.2-0.4 m ³ / t • min.

 The essence of the proposed method is as follows.

 The studies made it possible to establish the optimal method and mode of extraction of metals from metal-containing spent catalysts based on aluminum and (or) silicon oxides from the point of view of the processed object.

 It was found that as a result of plasma-arc heating in the claimed conditions of the initial mixture containing the above spent catalysts in a mixture with lime fluxes and (or) alumina, valuable components contained in the catalysts (such as nickel, cobalt, tungsten, molybdenum, etc. . metals), go into ferrous alloys, while dump slag in its structure and composition is a molten mortar.

 Studies have shown that the iron fed in the form of iron chips in the melt, acts as a collector and thereby contributes to the maximum extraction of valuable components.

 It was experimentally confirmed that for the organization of the optimal process, the temperature regime, the amount of reducing agent (table 1) and collector (iron) (table 2), as well as inert gas for slag purging are also essential.

Moreover, if the slag temperature is maintained below 1600 ^o C, the metal content in the slag rises above 0.1%, while the slag temperature rises above 1650 ^o C, the resistance of the refractory masonry of the plasma furnace decreases sharply.

 When the content of the carbon-containing reducing agent is less than 0.06 of the weight of the starting material, the metal content in the dump slag increases, with an increase of this value above 0.08, the metal in the slag does not decrease.

Inert gas purging of the slag is required to reduce the metal content in the slag. In the absence of purging, the metal content in the slag does not decrease to the level of the dump. When purging with an intensity below 0.2 m ³ / t • min, the metal content in the slag continues to be higher than that achieved under the claimed mode, while increasing the intensity of the blast above 0.4 m ³ / t • min, there is no further decrease in the metal content in the slag.

 When the ratio of the amount of introduced iron to the weight of the starting material is less than 0.15, a significant increase in the metal content in the slag is observed.

 Below are examples of specific implementations of the proposed method, confirming both the possibility of carrying out the invention with the implementation of the specified purpose, and the possibility of obtaining the above technical result.

 Examples of specific implementations of the proposed method.

Example 1. Processing was performed on the spent catalyst containing 17% tungsten and 3% nickel, based on aluminum oxide. The mixture, consisting of 200 kg of catalyst and 100 kg of limestone, was loaded into a semi-industrial plasma-arc furnace with a charge of 300 kg. Melting is carried out at a temperature of 1650 ^o C, a plasma-forming nitrogen gas. After directing the charge to the bath, reducing agent-coke was continuously fed, the total consumption was 27 kg with a carbon content of 85%. In the first half of the heat, iron chips in the amount of 42 kg were fed to the melt bath. After its melting, the bath was purged with neutral nitrogen gas with a specific intensity of 0.2 m ³ / t • min. The resulting ferroalloy, containing 29.8% tungsten and 5.3% nickel, was discharged from the furnace at a temperature of 1370 ^o C. Slag was discharged from the furnace at a temperature of 1600 ^o C. The slag obtained in its composition and structure corresponded to a high-alumina cement with a composition of 75% Al ₂ O ₃ and 25% CaO.

Example 2. The spent catalyst for the oxidation of sulfur dioxide containing 8% vanadium pentoxide, 74% silicon oxide was subjected to processing. A mixture consisting of 200 kg of catalyst and 200 kg of limestone was loaded into a semi-industrial plasma-arc furnace with a charge of 300 kg. Melting is carried out at a temperature of 1620 ^o C, a plasma-forming nitrogen gas. After the charge was melted, reducing coke in the amount of 16 kg and iron in the form of iron shavings in the amount of 50 kg were continuously fed to the bath. After melting the iron chips, the bath was purged with neutral nitrogen gas with a specific blast intensity of 0.35 m ³ / t • min. The resulting ferroalloy contained 25% vanadium, it was released at a temperature of 1350 ^o C. Slag from the furnace was released at a temperature of 1620 ^o C. In its composition and structure, the slag corresponded to cement grade 400.

Example 3. The spent aluminosilicate platinum catalyst containing 63.5% silica: 23.5% alumina and 0.9% platinum was processed. The mixture, consisting of 300 kg of catalyst and 321 kg of alumina, was loaded into a semi-industrial plasma-arc furnace with a charge of 300 kg. Melting is carried out at a temperature of 1650 ^o C, a plasma-forming nitrogen gas. After the charge was melted, a coke reducing agent in the amount of 18 kg and iron in the form of chips in the amount of 20 kg were continuously fed to the bath. After the iron was melted, the bath was purged with neutral gas with nitrogen with a specific blast intensity of 0.4 m ³ / t • min. The resulting ferroalloy contained 16% platinum, it was discharged from the furnace with a temperature of 1380 ^° C. Slag was released from the furnace with a temperature of 1600 ^° C. Slag composition: 60% silicon oxide and 40% aluminum oxide. After grinding, it is a fireclay mortar.

 The results of experimental studies to identify optimal conditions for the proposed method are shown in tables 1,2.

As follows from the analysis of the data, the best results are achieved by maintaining the temperature of the melt loaded into the plasma furnace spent catalyst in a mixture with lime fluxes at a level of 1600-1650 ^o C, with the supply of molten carbon reducing agent to the bath, supplied in an amount (0.06-0 , 08) by weight of the starting material (spent catalyst) and iron supplied in an amount of at least 0.15 by weight of the starting material, followed by purging the melt with a neutral gas with a specific intensity of blasting, 0.2-0.4 m ³ / t • min.

 Thus, the inventive method successfully solves the problem of complex cost-effective processing of spent metal-containing catalysts made on the basis of aluminum oxide and (or) silicon in terms of achieving high levels of extraction of valuable components contained in spent catalysts to obtain expensive cement grades from processing, high-quality fireclay, as well as provide environmental requirements for the process.

Claims (1)

The method of extracting metals from metal-containing spent catalysts based on aluminum and / or silicon oxides, including processing them by heating, characterized in that the processing is carried out by melting the catalysts in a mixture with lime fluxes and / or alumina using plasma-arc heating at 1600 1650 ^o C with the supply of a carbon-containing reducing agent in an amount of 0.06 0.08 mass of the starting material and iron in an amount of not less than 0.15 mass of the starting material, followed by purging of the obtained melt with neutral g gas with a specific intensity of the blast of 0.2 - 0.4 m ³ / t • min.

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