SU982362A1 - Method of extracting molybdenum - Google Patents

Abstract

A method of extracting molybdenum from cinders of molybdenum products, including soda alkalization when heated to produce cake and molybdenum-containing solution, characterized in that, in order to increase the degree of extraction and reduce the consumption of reagents, leaching is carried out at a soda consumption of 50 to 70% by weight of scum for 3 to 6 hours, followed by treatment with a nitric sulfate solution at a liquid to solid ratio of 2.0, 8: 1, a temperature of 80-95 ° C, and a dosage of the resulting acidic solution to a molybdenum-containing solution ( H 1.2 - 2.5.

Description

19 The invention relates to the field of rare metals metallurgy, namely to methods for extracting molybdenum. A known method of recycling cinder obtained as a result of oxidative roasting of molybdenum concentrate or middling includes two-stage ammonium leaching of cinder followed by a 2-3 stage sodam leaching cakes formed after ammonia treatment. Ammonium solutions are purified from heavy metals (copper, nickel, etc.) with sulfuric ammonium, after which they are sent to the separation of molybdenum as a salable salt — ammonium paramolybdate — and sodium chloride is recycled to produce a double ammonium molybdenum sodium salt. by introducing the required amount of ammonium chloride (or sulphate) ammonium Cl 1 There is also known a method for extracting molybdenum from butts of molybdenum products, including soda. baking by heating to produce a cake and a molybdenum-containing solution 2, This method is the most close to the IMT in technical essence and the achieved result. The disadvantages of this method are low recovery and long consumption of reagents. The aim of the invention is to increase the recovery rate and reduce the reagent flow. The goal is achieved by the fact that in the method of extracting molybdenum from cinders of molybdenum products, including soda leaching in priming to produce cake and molybdenum-containing solution, leaching takes place at a flow rate of 50–70% to the weight of cinder for 3 to 6 hours with the next treating the cakes with a nitrous-sulphate solution at a ratio of liquid to solid 2-0.8: 1, temperature 80-95 ° C and dosing the resulting acidic solution to molybdenum containing solution to a pH of 1.2-2.5. The method is as follows. The calcine after calcining the molybdenum product is leached in the reactor — with pneumatic (like a wad) or mechanical stirring or in a cascade of reactors connected in series, while maintaining a temperature of 80 -. The pulp after filtration is filtered to separate the cake from the molybdenum-containing soda solution. The cake is washed on the filter with water (the solution is added to the molybdenum-containing solution) and treated with a nitric sulfate solution when heated to 80-95 ° C. The nitric sulfate solution is prepared by mixing sulfuric and nitric acids, the latter being added at the rate of 10% excess over stoichiometric for oxidation of sulfide sulfur remaining in the calcine after calcining. The acidic pulp is filtered, the precipitate is washed with water and repulped, and then pumped to the tailings; An acidic solution is used to neutralize the soda molybdenum-containing solution. The dosage of the acidic solution to the molybdenum-containing solution is carried out in a cascade of two reactors connected in series. The process is controlled by the pH value obtained from mixing the solution, which is regulated by pneumatic valves on the solution supply lines and monitored by the pH meter. The resulting solution with a pH of 1.2-2.5 is directed to the extraction of molybdenum by the sorption method using ion exchange resins. It does not require cleaning solutions from impurities; product paramolybdate satisfies the requirements for hch brand products. Thus, when processing waste cake obtained after soda melting of a cinder of molybdenum products with a nitrogen-sulphate solution, acid decomposition of films of poorly soluble carbonates and hydroxides on the particles of the initial compounds occurs, as well as partial dissolution of the minerals of the host rocks. As a result, the oxidized molybdenum is further extracted into the solution, and the sulfide forms and lower valencies of molybdenum are oxidized by nitric acid in the solution being treated, which also contributes to the depletion of the solid part of the pulp in molybdenum. Primer p. The calcine after roasting molybdenite middling in the furnace of the fluidized bed contains,%: molybdenum

33.2; copper 3.12; iron (total) 5.81; sulfide sulfur 0.6; alumina 6.8; silica 2.76.

Exaggeration in soda is carried out by P reactors with mechanical stirring.

15 m each, equipped with a steam jacket for heating. SODA is served as a saturated solution with a suspension at a ratio to the weight of the calcine (W: T) equal to 1: 4, n the consumption of soda 70% by weight of the calcine. The temperature in the alkalization process is maintained at 95 ° C, the duration of the process is 6 hours.

After alkalizing, the slurry is filtered on a frame filter press, the cake cake is washed for 10 minutes with process water from the circulating water supply system. Promoid is combined to molybdenum-containing soda solution.

The washed cake is treated with nitrogen-sulphate in two stainless steel reactors of 4 m each, connected in series, in terms of T: W 1: 2, temperature 95 ° C and duration of treatment 1 h. The nitrogen-sulphate solution is prepared on the basis of sulfuric acid content. and nitric acids, respectively 12.0 and 2.0%.

After processing, the acidic pulp is filtered on a filter press, the precipitate is washed with technical water, and the solution after analysis for molybdenum, excess acidity and impurities are pumped out at the tailings pond. Acid solution with content, g / l: molybdenum 20-25; iron 12-17; nitrate - ion 0.4-0.6; sulphate ion 80-110 and a total acidity of 60–80 g / l are sent for mixing with molybdenum-containing soda solution.

The mixing of the solutions is carried out in a cascade of reactors p by mechanical agitation. The dosing of the acidic solution was carried out according to the pH value in the tail reactor of the cascade, which was maintained by automatic pneumatic valves at the signal of the pH meter sensor.

These conditions for the dosage of the acidic solution to the molybdenum-containing soda solution provide a sufficiently complete dissolution of the iron hydroxide falling out of the solution during neutralization, and are necessary for the subsequent operation of sorption processing of the solutions in order to extract the molybdenum to the anion exchanger. If in an acidic solution the iron content exceeds 20/25 g / l (i.e. during processing, for example, ferrous molybdenum-containing cakes), the pH value after dosing is maintained within 0.8 - 1.2 - to create more favorable conditions. hydroxides dissolving.

The table shows the main data obtained during pilot testing on the proposed and known methods.

The results of pilot tests confirm that the implementation of the proposed method improves the extraction of molybdenum from the calcine, reduces the specific consumption of chemicals, in particular soda, for improvement.

The choice of the leaching duration limit of 3-6 hours, as well as the consumption of soda for alkalization of 50-70% by weight of calcine, was determined experimentally. With a duration of less than 3 hours, the content of molybdenum in the cake increases, i.e. the degree of its extraction from the calcine into the solution is reduced. With increasing time above; more than 6 hours, the degree of extraction of molybdenum changes insignificantly.

An analysis of the results obtained with the different consumption of soda needed for alkalization shows that the optimal limit is in the range of 50-70% by weight of the calcine and depends mainly on the composition of the calcine and the content of molybdenum in it. For example, as the molybdenum content of the desired calcine is reduced, the soda consumption increases. At a flow rate of up to 70% by weight of the calcine, the degree of extraction of molybdenum into the solution is almost not likely due to the formation of carbonate films on the surface of the starting materials. Reducing soda consumption to less than 50% by weight of calcine leads to a decrease in the extraction of molybdenum into the solution.

The parameters and modes of the subsequent nitric-sulfuric acid treatment of the cake obtained after soda extraction (calcination, were also determined experimentally and confirmed by experimental tests). For example, when determining the limit of the ratio of liquid to solid, equal to Оj8 - 2: 1, showed that the ratio is W: T

0.8: 1, the extraction of molybdenum into acidic solution is reduced due to the high salt background. In this process, it is difficult to process thick pastes. Above the ratio L; -T 2: 1, the extraction increases slightly, and in this case the consumption of acid for processing increases, the dosage regimen of the acidic solution to the molybdenum-containing solution, which controls the pH of 1.2-2.5, is selected based on , that iron hydroxide, which is formed at the first moment as a result of comparative test data, after processing of butt and

the dosage of the acidic solution is completely and quickly dissolved in the resulting mixed solution. When the pH value is more than 2.5, dissolution goes slower, since in this case the limit of iron hydrolysis is close, and it is impractical to neutralize below pH 1.2 because of the need to introduce additional acid for neutralization, and also because the processing of solutions with A pH of 1.2 in subsequent operations is difficult (for example, in the sorption of molybdenum t5 by anion exchangers). according to the proposed prototype scheme

Claims (1)

METHOD FOR REMOVING MOLYBDENE from cinder of molybdenum products, including soda leaching when heated to obtain cake and a molybdenum-containing solution, characterized in that, in order to increase the degree of extraction and reduce the consumption of reagents, the leaching is carried out at a flow of soda of 50 - 70% by weight of the cinder for 3 6 hours, followed by treating the cakes with a nitric sulfate solution at a liquid to solid ratio of 2 0.8: 1, a temperature of 80 - 95 ° C and a dosage of the resulting acid solution to a molybdenum-containing solution, to a pH of 1.2 - 2.5.