RU2466199C1 - Processing method of waste molybdenum-aluminium-containing catalyst - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method involves sintering of catalyst, leaching of sinter and deposition of aluminium at the first stage and molybdenum at the second stage from the solution. Catalyst is mixed with soda solution at solid-to-liquid ratio of 1:0.8÷1 prior to sintering. Soda consumption is taken based on 200-400 kg/t of raw material. The obtained sinter is subject to water leaching during 1-2 hours at temperature of 50-80°C. At that, molybdenum is deposited in the form of calcium molybdate at the second stage.

EFFECT: increasing molybdenum extraction efficiency.

3 cl, 1 ex

Description

The invention relates to hydrometallurgy of rare metals and can be used in the processing of spent molybdenum-containing catalysts.

Known methods for the extraction of molybdenum, based on preliminary oxidative calcination of the catalysts and subsequent carbonate leaching.

A known method of extracting molybdenum from a molybdenum-containing cinder (patent RU No. 2296802, IPC C22B 34/34, C22B 3/12), which consists in processing cinder with a solution of carbonate and potassium nitrate.

Closest to the claimed is the method described in SU No. 704654 - a method for processing spent molybdenum-aluminum-containing catalyst, comprising sintering the catalyst, leaching cake and precipitation from aluminum solution in the first stage and molybdenum in the second stage.

The disadvantage of this leaching method is the relatively low extraction of molybdenum in solution.

The technical result of the invention is the creation of an effective method for the extraction of molybdenum.

The technical result is achieved in that the extraction of molybdenum from the spent molybdenum-containing catalyst includes the steps of:

- mixing the catalyst with a solution of soda;

- sintering of the resulting paste;

- leaching with water;

- precipitation of aluminum;

- precipitation of calcium molybdate.

The catalyst is kneaded with a soda solution at a ratio of T: W = 1: 0.8-1 at a soda flow rate of 200-400 kg / t of raw material. The resulting cake is subjected to leaching with water for 1-2 hours at a temperature of 50-80 ° C. In the first stage, aluminum is precipitated, in the second stage, molybdenum in the form of calcium molybdate. To obtain aluminum-free calcium molybdate, a solution of hydrochloric acid is introduced into the obtained filtrate in the first stage at a temperature of 20-25 ° C to a pH of 8.2-8.5 to precipitate aluminum. The process is carried out with stirring for 15-20 minutes. The resulting precipitate is filtered off. In the second stage, calcium molybdate is precipitated. The process is carried out by introducing a solution of calcium chloride into the filtrate to a pH of 6.5-6.8 at a temperature of 95-100 ° C and then stirring for 60 minutes. The resulting precipitate is calcium molybdate is dried.

Sintering is carried out at a temperature of 450-500 ° C for 40-60 minutes. After sintering, the resulting cinder is leached with water. According to the leaching reaction, sodium molybdate and sodium aluminate are formed in the solution.

MoO ₃ + Al ₂ O ₃ + 2Na ₂ CO ₃ + H ₂ O = Na ₂ MoO ₄ + 2NaAlO ₂ + CO ₂ + H ₂ O

The proposed method was tested on a spent molybdenum-aluminum-containing catalyst. Content,%: MoO ₃ - 17.54; Al ₂ O ₃ 63.13; NiO - 2.69; Co ₃ O ₄ - 2.61; V ₂ O ₅ - 2.97.

Example 1. Before sintering, a catalyst was kneaded with a soda solution at a soda flow of 400 kg / t with a ratio of T: W = 1: 1; sintering temperature 450 ° С, sintering time 40 min. The resulting spec was leached for 2 hours, T: W _high = 1: 4; leaching temperature 75 ° C.

The resulting solution contained, g / l: Mo — 27.85; Al - 1.49; Co - 0.0012; Ni is 0.0013; V is 0.0018. Molybdenum recovery was 98.2%.

To obtain calcium molybdate with a low content of impurities, the deposition process was carried out in two stages. At the first stage of precipitation, hydrochloric acid was introduced into the resulting solution with a pH of 11.3 to a pH of 8.5. Extraction of aluminum from solution to precipitate was 99.2%. After filtration in the second stage, the precipitation was carried out by introducing calcium chloride to a pH of 6.8 at boiling point, followed by stirring for 60 minutes. The resulting precipitate contained,%: Al - 0.064; Si - 0.017. The recovery of molybdenum from the solution is 98%.

Claims (3)

1. A method of processing spent molybdenum-aluminum-containing catalyst, including sintering the catalyst, leaching the cake and precipitating aluminum from the solution in the first stage and molybdenum in the second stage, characterized in that before sintering, the catalyst is kneaded with a soda solution at a ratio of T: W = 1 : 0.8 ÷ 1, moreover, the soda consumption is taken from the calculation of 200-400 kg / t of raw materials, the obtained cake is subjected to leaching with water for 1-2 hours at a temperature of 50-80 ° C, while in the second stage molybdenum is precipitated in the form of molybdate calcium. 2. The method according to claim 1, characterized in that in order to precipitate the aluminum contained in the solution, hydrochloric acid is introduced in the first stage to a pH of 8.2-8.5 at a temperature of 20-25 ° C. 3. The method according to claim 1, characterized in that for the precipitation of calcium molybdate carry out the introduction of a solution of calcium chloride to a pH of 6.5-6.8 at a temperature of 95-100 ° C.