A method for separating ferromolybdenum from waste iron-molybdenum catalyst

Abstract

The present invention belongs to the technical field of iron-molybdenum separation, and more specifically, relates to a method for separating molybdenum iron from waste iron-molybdenum catalysts. The method comprises the following steps: subjecting the waste iron-molybdenum catalyst to reduction acid leaching, adding a promoter, using alkaline solution as a precipitant, adjusting the pH of the solution to alkaline by a parallel flow equal pH precipitation method, reacting at a temperature of 60 to 90°C, aging for 6 to 8 hours, and using magnetic separation to achieve solid-liquid separation of the alkaline slurry to obtain molybdenum-containing alkaline solution and magnetic iron slag, achieving effective separation of molybdenum and iron, and a molybdenum recovery rate of more than 99%, wherein the molybdenum-containing alkaline solution is used to prepare pure molybdic acid by pH adjustment.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical separation, and relates to the technical field of a method for separating ferromolybdenum from waste iron-molybdenum catalysts. Background Art

[0002] Molybdenum is a refractory rare metal with a small reserve. Its status in the national economy is becoming more and more prominent. Industrial waste catalysts are often discarded as waste materials. The main components of waste iron-molybdenum catalysts are Fe2O3 and MoO3, and the Mo content is about 30% to 50%. Therefore, recycling the molybdenum in it is not only a full utilization of precious resources, but also can create considerable economic benefits.

[0003] Conventional acid and alkaline leaching methods can achieve the extraction of molybdenum. However, the dissolution rate of molybdenum is low under acidic conditions, resulting in a low molybdenum recovery rate. Alkaline leaching can increase the leaching rate of molybdenum, but the presence of iron will make the filtration of alkaline slurry difficult, resulting in poor separation of iron and molybdenum.

[0004] Therefore, it is necessary to find an efficient separation method for iron and molybdenum to improve the recovery rate of molybdenum in waste iron-molybdenum catalysts, so as to improve the resource utilization rate and recovery value of waste catalysts. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a method for separating ferromolybdenum from waste iron-molybdenum catalysts.

[0006] To achieve the above object, the present invention is implemented by the following technical solutions:

[0007] The present invention provides a method for separating ferromolybdenum from waste iron-molybdenum catalyst, the method comprising the following steps:

[0008] The waste iron-molybdenum catalyst is subjected to reduction acid leaching, a promoter is added, and an alkali solution is used as a precipitant. The pH of the solution is adjusted to alkaline by a parallel flow equal pH precipitation method. The reaction temperature is 60-90°C, and the aging is carried out for 6-8 hours. The solid-liquid separation of the alkaline slurry is achieved by magnetic separation to obtain molybdenum-containing alkali solution and magnetic iron slag, thereby achieving effective separation of molybdenum and iron, with a molybdenum recovery rate of more than 99%. The molybdenum-containing alkali solution is used to prepare pure molybdic acid by pH adjustment.

[0009] The present invention adopts the method of reducing acid leaching to realize the dissolution and partial reduction of iron, so that the iron in the slurry exists in the form of trivalent iron and divalent iron. The promoter used in the present invention is a combination of one or more of oxalate, tartrate and citrate, which can accelerate the dissolution of iron and the reduction reaction of trivalent iron, and has the effect of improving the reaction efficiency. At the same time, the waste catalyst is activated to provide more erosion channels, which is beneficial to the subsequent alkaline leaching of molybdenum. The pH of the solution is adjusted to alkaline, so that the trivalent iron and divalent iron in the solution generate magnetic ferroferric oxide. Since molybdenum is more soluble in alkaline solution, the leaching effect of molybdenum in the acid leaching process is poor, and some molybdenum cannot be dissolved. Therefore, in the process of adjusting the pH to precipitate iron, molybdenum will be further leached, and the precipitation is terminated. The magnetic separation method is adopted to realize the effective separation of molybdenum-containing alkali solution and magnetic iron slag in the alkaline slurry, which solves the problem of difficult filtration and poor separation effect of alkaline slurry caused by simple alkaline leaching of molybdenum, improves the separation effect of molybdenum and iron, and improves the recovery rate of molybdenum.

[0010] Further, the reducing acid leaching reducing agent is one or a combination of two of sodium pyrosulfite, sodium dithionite, sodium sulfite, sodium thiosulfate, and hydrazine hydrate;

[0011] Further, the molar ratio of the reducing agent to the iron in the waste iron-molybdenum catalyst is 0.3 to 1:1;

[0012] Furthermore, the accelerator is one or a combination of oxalate, tartrate, and citrate;

[0013] Furthermore, the molar ratio of the amount of the promoter added to the iron in the waste iron-molybdenum catalyst is 0.1 to 1:1;

[0014] Furthermore, the alkali in the alkali solution as the precipitant is one or a combination of ammonia water, sodium hydroxide, and potassium hydroxide;

[0015] Furthermore, the pH control range in the iso-pH precipitation method is 9 to 11;

[0016] Furthermore, the molybdenum-containing alkali solution is used to prepare pure molybdic acid by adjusting pH.

[0017] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0018] The technical principle of the present invention is to dissolve and partially reduce the iron in the waste iron-molybdenum catalyst by reducing acid leaching, and adjust the pH by alkali to make trivalent iron and divalent iron generate ferroferric oxide, and molybdenum exists in the form of molybdate ions in the alkaline solution. The molybdenum-containing alkali solution and magnetic ferroferric oxide in the alkaline slurry are effectively separated by magnetic separation, and the molybdenum recovery rate reaches more than 99%, wherein the molybdenum-containing alkali solution is used to prepare pure molybdic acid by pH adjustment.

[0019] The beneficial effects of the present invention are that it can achieve effective solid-liquid separation of iron and molybdenum in waste iron-molybdenum catalysts, achieve effective recovery of molybdenum, and achieve effective recycling of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the solid-liquid separation of molybdenum-containing slurry before and after the magnetic field condition of the present invention;

[0021] Figure 2 It is a comparative schematic diagram of the molybdenum-containing slurry before and after solid-liquid separation under magnetic field conditions in the comparative example of the present invention. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can implement the invention with reference to the description. However, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0023] Example 1

[0024] A method for separating ferromolybdenum from waste iron-molybdenum catalyst comprises the following steps:

[0025] The waste iron molybdenum catalyst is subjected to a reduction acid leaching reaction with 0.5 times of hydrazine hydrate, and 0.5 times of citric acid is added. The acid-soluble slurry and sodium hydroxide solution are adjusted to an alkaline pH by a parallel flow equal pH precipitation method, and the pH is stabilized at 10.5. The reaction temperature is 90°C, and the aging is performed for 6 hours. The solid-liquid separation of the alkaline slurry is achieved by magnetic separation to obtain molybdenum-containing alkaline solution and magnetic iron slag, thereby achieving effective separation of molybdenum and iron, and the molybdenum recovery rate is above 99.5%, wherein the molybdenum-containing alkaline solution is adjusted to pH 1 to prepare pure molybdenum acid.

[0026] Example 2

[0027] A method for separating ferromolybdenum from waste iron-molybdenum catalyst comprises the following steps:

[0028] The waste iron molybdenum catalyst is subjected to a reduction acid leaching reaction with 0.5 times of sodium dithionite, and 0.5 times of citric acid is added. The acid-soluble slurry and sodium hydroxide solution are adjusted to alkaline pH by a parallel flow equal pH precipitation method, and the pH is stabilized at 11. The reaction temperature is 90°C and the aging is carried out for 6 hours. The alkaline slurry is separated into solid and liquid by magnetic separation to obtain molybdenum-containing alkaline solution and magnetic iron slag, thereby achieving effective separation of molybdenum and iron. The molybdenum recovery rate is more than 99.1%, and the molybdenum-containing alkaline solution is adjusted to pH 1 to prepare pure molybdenum acid.

[0029] Example 3

[0030] A method for separating ferromolybdenum from waste iron-molybdenum catalyst comprises the following steps:

[0031] The waste iron molybdenum catalyst is subjected to a reduction acid leaching reaction with 0.8 times of sodium metabisulfite, and 0.5 times of tartaric acid is added. The acid-soluble slurry and sodium hydroxide solution are adjusted to alkaline pH by a parallel flow equal pH precipitation method, and the pH is stabilized at 10. The reaction temperature is 90°C and the aging is carried out for 6 hours. The alkaline slurry is separated into solid and liquid by magnetic separation to obtain molybdenum-containing alkaline solution and magnetic iron slag, thereby achieving effective separation of molybdenum and iron. The molybdenum recovery rate is more than 99.3%, and the molybdenum-containing alkaline solution is adjusted to pH 1 to prepare pure molybdenum acid.

[0032] Comparative Example 1

[0033] Compared with Example 1, the difference is that no reduction treatment is performed, and the remaining steps and parameters are the same. The magnetic separation method cannot achieve solid-liquid separation of the alkaline slurry, the atmospheric pressure filtration speed is slow, and it is difficult to wash, and the molybdenum recovery rate is only 50.2%.

Claims

1. A method for separating ferromolybdenum from waste iron-molybdenum catalyst, characterized by comprising the following steps: The waste iron molybdenum catalyst is mixed with a reducing agent for reduction acid leaching, one or a combination of oxalate, tartrate and citrate are added as a promoter, alkali solution is used as a precipitant, and the pH of the solution is adjusted to alkaline by a parallel flow equal pH precipitation method, the reaction temperature is 60-90°C, and the aging is 6-8h. The solid-liquid separation of the alkaline slurry is achieved by magnetic separation to obtain molybdenum-containing alkali solution and magnetic iron slag, thereby achieving effective separation of molybdenum and iron, and the molybdenum recovery rate is more than 99%, wherein the molybdenum-containing alkali solution is used to prepare pure molybdic acid by pH adjustment.

2. A method for separating ferromolybdenum from waste iron-molybdenum catalyst according to claim 1, characterized in that: The reducing agent is one or a combination of two of sodium pyrosulfite, sodium dithionite, sodium sulfite, sodium thiosulfate and hydrazine hydrate.

3. A method for separating ferromolybdenum from waste iron-molybdenum catalyst according to claim 1, characterized in that: The molar ratio of the reducing agent to the iron in the waste molybdenum-iron catalyst is 0.3 to 1:

1.

4. The method for separating ferromolybdenum from waste iron-molybdenum catalyst according to claim 1, characterized in that: The molar ratio of the amount of the promoter added to the iron in the waste molybdenum-iron catalyst is 0.1 to 1:

1.

5. The method for separating ferromolybdenum from waste iron-molybdenum catalyst according to claim 1, characterized in that: The alkali solution used as the precipitant is one or a combination of ammonia water, sodium hydroxide and potassium hydroxide solution.

6. The method for separating ferromolybdenum from waste iron-molybdenum catalyst according to claim 1, characterized in that: The pH control range in the iso-pH precipitation method is 9-11.

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