RU2536615C1 - Method for processing of sulphide and mixed molybdenum-containing concentrates - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method for processing of sulphide and mixed molybdenum-containing concentrates involves mixing of concentrates with an additive of calcium oxide taken in the quantity of 2-2.5 times excess of the stoichiometrically required one for connection of molybdenum, rhenium and sulphur at oxidation annealing into non-volatile compounds. Then, oxidation annealing of the mixture is performed during 60-120 minutes. Leaching of the obtained stub end is performed in two stages. Water leaching is performed at the first stage during 60-80 minutes at S:L ratio of at least 1:2 and temperature of 90-95°C for selective extraction of rhenium into the solution. At the second stage, leaching is performed by means of a solution of alkali metal carbonate for extraction into the solution of molybdenum and the rest rhenium.

EFFECT: improving efficiency of the method and selective separation of molybdenum and rhenium.

2 cl, 1 dwg, 1 tbl, 1 ex

Description

The invention relates to the field of non-ferrous metallurgy and can be used to extract molybdenum and rhenium from sulfide and mixed molybdenum-containing concentrates.

There is a method of oxidative roasting of molybdenum concentrate and intermediate products in a continuous shaft furnace, which includes supplying air to the furnace and removing calcining gases, while in the upper loading zone of the furnace there is a movement of solid and gas phases having a temperature of 600-700 ° C in one direction, which provides oxidation of molybdenum, complete combustion of organic substances and a high degree of distillation of rhenium and osmium into the gas phase (RF patent No. 2106420, IPC 6 C22B 34/34, publ. 1998.03.10).

The disadvantages of the method are firing at elevated temperatures, which requires significant energy consumption, and the complexity of the allocation of rhenium and osmium from the gas phase.

A known method of extracting molybdenum from oxidized ores or concentrates, including mixing them with lime (CaO) in an amount of 3-4%, firing the mixture at a temperature of 700-850 ° C, leaching the cinder with a 2-3% solution of sodium carbonate at a temperature of 90 ° C and ratio T: W 1: 2.5, followed by separation of the cake from the filtrate and extraction of molybdenum from the filtrate by precipitation of molybdenum in the form of trisulfide or by ion-exchange method (A.N. Zelikman. Molybdenum. M .: Metallurgy, 1970, pp. 109-110 )

The disadvantages of this method are:

- the need to capture toxic sulfur dioxide released in the gas phase due to incomplete sulfur binding during the firing process;

- loss of rhenium with exhaust gases of sulfur dioxide;

- increased energy costs during firing at temperatures above 700 ° C;

- insufficiently complete extraction of molybdenum into the solution during cinder leaching.

The closest set of essential features is a method for processing sulfide and mixed molybdenum-containing concentrates, including mixing them with additives selected from MgO, MgCO ₃ , CaO, CaO ₂ , CaCO ₃ , BaO, BaO ₂ , BaCO ₃ , in an amount of 100-120% from stoichiometrically necessary for sulfur binding, oxidative roasting of the mixture at a temperature of 450-650 ° C, leaching of the cinder with a solution of alkali metal carbonate (sodium or potassium) with a concentration of 150-200 g / dm ³ to obtain a solution containing molybdenum and rhenium, and metal recovery from prod such as are for leaching (RF patent №2393253, IPC 8 S22V 34/34, publ. 2010.06.27).

The disadvantage of this method is the insufficiently high efficiency due to the presence in the cinder of poorly soluble compounds of molybdenum and rhenium, which prevent their further conversion to solution, as well as the impossibility of selective separation during soda leaching of molybdenum and rhenium into separate products from collective molybdenum solution.

The technical result of the claimed invention is to increase the efficiency of the method of processing molybdenum-containing concentrates by completely converting molybdenum and rhenium into the corresponding highly soluble calcium compounds CaMoO ₄ and Ca (ReO ₄ ) ₂ and sulfur into poorly soluble CaSO ₄ during oxidative roasting and subsequent selective separation of molybdenum and rhenium.

This result is achieved by the fact that in the method for processing sulfide and mixed molybdenum-containing concentrates, comprising mixing the concentrates with calcium oxide, oxidizing the mixture, leaching the calcined solution with an alkali metal carbonate solution and extracting molybdenum and rhenium from the solution, calcium oxide is added in an amount of 2 -2.5-fold excess of stoichiometrically necessary for the binding of molybdenum, rhenium and sulfur during oxidative firing, leaching of the cinder obtained bred in two stages, while in the first stage, water leaching is carried out for 60-80 minutes at T: W at least 1: 2 and a temperature of 90-95 ° C for selective extraction of rhenium into the solution, and in the second stage, leaching is carried out with a carbonate solution alkali metal to extract molybdenum and the remaining rhenium into the solution. In addition, oxidative firing is carried out for 60-120 minutes.

The addition of CaO to the concentrate in an amount of 2-2.5-fold excess of the stoichiometrically necessary for the binding of molybdenum, sulfur, and rhenium allows the complete conversion of sulfur, molybdenum, and rhenium to non-volatile compounds during oxidative firing: SO ₂ in CaSO ₄ , and Mo and Re in CaMoO ₄ and Ca (ReO ₄ ) ₂ , reactions (1), (2), (3):

$$\mathrm{<figure-callout\; id="2"\; label="S\; O"\; filenames="00000004.png"\; state="\{\{state\}\}">S\; </figure-callout>}{O}_{}{}_2+CaO+\mathrm{one}/2{\mathrm{<figure-callout\; id="2"\; label="O"\; filenames="00000004.png"\; state="\{\{state\}\}">O</figure-callout>}}_2=CaS{O}_{\mathrm{four}}(\mathrm{one})$$

$$Mo{O}_3+CaO=CaMo{O}_{\mathrm{four}}(2)$$

$${\mathrm{Re}}_2{O}_7+CaO=Ca{(\mathrm{Re}{O}_{\mathrm{four}})}_2(3)$$

This determines the possibility of selective separation of molybdenum and rhenium during cinder leaching in two stages. It was water leaching of calcium perrenate that was chosen as a selective rhenium solvent, since it has a fairly good solubility, and the calcium molybdate formed as a result of oxidative firing does not dissolve in water.

In the first stage, rhenium is extracted from the cinder with an aqueous solution for 60-80 minutes at T: W of at least 1: 2 and a temperature of 90-95 ° C. Since calcium molybdenum compounds are poorly soluble in water, and calcium rhenium compounds have a sufficiently high solubility, this allows rhenium to be selectively transferred into an aqueous solution with a complete recovery of up to 76%. To extract molybdenum, the cakes after the first leaching stage are treated with solutions of sodium carbonate (Na ₂ CO ₃ ) or potassium carbonate (K ₂ CO ₃ ) with a concentration of 150-200 g / dm ³ , which allows 99.8% to transfer molybdenum and residual the amount of rhenium to obtain, during subsequent operations, pure marketable products of molybdenum and rhenium according to known technologies.

The claimed method of processing molybdenum concentrates has been tested in laboratory conditions.

Example. Sulphide molybdenum concentrate of the South Shameysk deposit, containing, wt.%: 42.6 Mo; 0.004 Re; 31.9 S, in an amount of 15 g was mixed with calcium oxide in an amount of 25 g (which is a 2-fold excess of the stoichiometrically necessary for the binding of molybdenum, rhenium and sulfur during oxidative roasting). The resulting mixture weighing 40 g, containing, wt.%: 16,29 Mo; 0.0016 Re; 11.89 S; 42.56 Ca was placed in a PVK-1.4-8 muffle furnace and fired at 600 ° C with continuous supply of air oxygen (air flow 100 dm ³ / h) and a duration of 120 minutes. In this case, cinder and gases were formed. Gases were analyzed for the content of rhenium compounds by the calorimetric method, sulfur compounds were analyzed on a gas analyzer of the MGL-19.3A model. Rhenium and sulfur were not detected in the gases. After cooling, the cinder was unloaded from the furnace and subjected to analysis for the content of molybdenum, rhenium, sulfur, calcium. A cinder weighing 44.842 g, containing wt.%: 14.52 Mo; 0.0014 Re; 10.82 S; 37.91 Ca, was subjected to leaching in the first stage with an aqueous solution at T: W equal to 1: 2, temperature 95 ° C for 60 minutes to obtain a solution containing, mg / dm ³ : 4,5 Mo; 4.74 Re, and cake containing, wt.%: 14.693 Mo; 0,00034 Re. The extraction into the solution in the first stage was,%: 0.009 Mo; 75.9 Re, the resulting solution can be aimed at obtaining ammonium perrenate by known technologies. The cake was subjected to the second stage of leaching with a solution of sodium carbonate with a concentration of 200 g / dm ³ , the ratio T: W - 1: 4, at a temperature of 90 ° C for 60 min to obtain a solution containing 32.48 g / dm ³ Mo and 0.75 mg / dm ³ Re and the residue containing, wt.%: 0,055 Mo; <0.00001 Re. The extraction into the solution in the second stage was,%: 99.8 Mo; 24,0 Re, the resulting solution can be aimed at sequentially receiving first ammonium perrenate, and then calcium molybdate according to known technologies. The recovery in two-stage leaching was,%: 99.8 Mo and 99.9 Re.

Under similar conditions, oxidative calcination of a sulfide molybdenum-containing concentrate was carried out, containing, wt.%: 42.6 Mo; 31.7 S; 0.004 Re, with a variation in the addition of calcium oxide in an amount of 2-2.5-fold excess of the stoichiometrically necessary for the binding of molybdenum, rhenium and sulfur during oxidative firing, on the amount of soluble compounds CaMoO ₄ , CaSO ₄ and Ca (ReO ₄ ) obtained in the cinder ₂ can be judged by the intensity of the lines of the corresponding compounds in the x-ray shown in the drawing.

The results of experiments on leaching in two stages of the obtained cinder containing, wt.%: 14.52 Mo; 10.82 S; 37.91 Ca; 0.0014 Re are given in the table. At the same time, in the first stage, the water leaching of the cinder was carried out for 60-80 minutes at T: W of at least 1: 2 and a temperature of 90-95 ° C for the selective transfer of calcium perrenate into solution. In the second stage of leaching with a sodium carbonate solution, according to the conditions of the example, the cakes obtained under optimal conditions of aqueous leaching were subjected.

Thus, the proposed method provides, in comparison with the prototype, a high selective extraction of rhenium and molybdenum from molybdenum-containing concentrates due to:

- complete binding during firing of sulfur in the form of SO ₂ in CaSO ₄ , molybdenum in the form of MoO ₃ in CaMoO ₄ and rhenium in the form of Re ₂ O ₇ in Ca (ReO ₄ ) ₂ ;

- obtaining cinder containing molybdenum and rhenium in the form of molybdate and calcium perrenate in a form suitable for selective separation by hydrometallurgical method;

- transfer of rhenium into solution with selective water leaching by 75.9% and complete additional extraction of rhenium (24.0%) and molybdenum recovery by 99.8% with soda leaching of the residue from water leaching of cinder.

The results of experiments on leaching the cinder of molybdenum concentrate in two stages Temperature ° C Duration min Ratio, T: F The first stage - water leaching Stage Two - Carbonate Leaching Extract from the cinder,% Content Recovery in solution,% Content Recovery in solution% In solution, mg / DM ³ In cake,% In solution In the balance,% Mo Re Mo Re Mo Re Mo g / dm ³ Re mg / dm ³ Mo Re Mo Re Mo Re Prototype - - - - - - 99.8 98 99.8 98 The proposed method 80 60 1: 2 3.00 3.89 14,675 0,00041 0.006 67.5 90 60 1: 2 4.69 4.18 14.57 0,00035 0.008 74.0 95 60 1: 2 4,5 4.74 14,693 0,00034 0.009 75.9 32,48 0.75 0,055 0.00001 99.8 24.0 99.8 99.9 95 fifty 1: 2 3.92 3.84 14.61 0,00042 0.007 68.0 95 60 1: 2 4,5 4.74 14,693 0,00034 0.009 75.9 32,48 0.75 0,055 0.00001 99.8 24.0 99.8 99.9 95 80 1: 2 4.62 4.13 14.56 0,00035 0.008 74.0 95 90 1: 2 4.87 4.05 14,692 0,00039 0.012 72.1 95 60 1: 1 2.75 3.67 14.65 0,00053 0.006 62.5 95 60 1: 2 4,5 4.74 14,693 0,00034 0.009 75.9 32,48 0.75 0,055 0.00001 99.8 24.0 99.8 99.9 95 60 1: 3 7.42 4.26 14.72 0,00035 0.015 74.8 - -

Claims (2)

1. A method of processing sulfide and mixed molybdenum-containing concentrates, including mixing concentrates with the addition of calcium oxide, oxidizing the mixture, leaching the cinder with a solution of alkali metal carbonate and extracting molybdenum and rhenium from the solution, characterized in that the calcium oxide is added in an amount of 2-2, 5-fold excess of stoichiometrically necessary for the binding of molybdenum, rhenium and sulfur during oxidative firing into non-volatile compounds, the leaching of the cinder is carried out in two stages in this case, in the first stage, water leaching is carried out for 60-80 minutes at T: W of at least 1: 2 and a temperature of 90-95 ° C for selective extraction of rhenium into the solution, and in the second stage, leaching is carried out with an alkali metal carbonate solution to extract into a solution of molybdenum and the remaining rhenium. 2. The method according to claim 1, characterized in that the oxidative firing is carried out for 60-120 minutes.

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