A method for recovering tungsten and molybdenum from tungsten smelting slag

Abstract

The present invention provides a method for recovering tungsten and molybdenum from tungsten smelting molybdenum removal slag, and relates to the field of comprehensive utilization of tungsten and molybdenum waste. The present invention provides a method for recovering tungsten and molybdenum from tungsten smelting molybdenum removal slag, comprising the following steps: oxidative roasting the molybdenum removal slag to obtain oxidized molybdenum removal slag; mixing the oxidized molybdenum removal slag with a reducing agent, a slag forming agent, and an iron source, and then reducing and smelting to obtain a tungsten-molybdenum-iron alloy. The recovery method of the present invention is suitable for recovering tungsten and molybdenum from molybdenum removal slag, and the recovery rate of tungsten and molybdenum is more than 95%.

Description

Technical Field

[0001] The invention relates to the field of comprehensive utilization of tungsten and molybdenum wastes, and in particular to a method for recovering tungsten and molybdenum from tungsten smelting slag for removing molybdenum. Background Art

[0002] At present, most tungsten smelting enterprises use alkali decomposition-ion exchange / extraction process to produce ammonium paratungstate (APT). In the APT production process, molybdenum removal is required. The current molybdenum removal process is mostly based on the fact that molybdenum can be preferentially sulfided to form MoS under certain conditions. 4 2- Then, the pH value of the sulfurized solution is adjusted to 2.5-3.0 with acid to generate MoS 3 The molybdenum removal slag contains 15-35% of valuable metal molybdenum and 1.5-5% of tungsten. In the situation of tight tungsten and molybdenum resources and high prices, the recycling of molybdenum removal slag as a secondary resource has great prospect value.

[0003] At present, the process of treating molybdenum slag at home and abroad is to perform hydrometallurgy on the molybdenum slag to convert it into salts or oxides containing tungsten and molybdenum, and then use other reduction methods to purify the intermediate products containing tungsten and molybdenum into pure tungsten and molybdenum compounds. However, the existing hydrometallurgical technology generally has the disadvantages of complex process flow and low tungsten and molybdenum recovery rate (only 90wt%). Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for recovering tungsten and molybdenum from tungsten smelting molybdenum-removing slag, and the present invention can efficiently recover tungsten and molybdenum.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for recovering tungsten and molybdenum from tungsten smelting slag for removing molybdenum, comprising the following steps:

[0007] The molybdenum removal slag is subjected to oxidative roasting to obtain oxidized molybdenum removal slag;

[0008] The oxidative molybdenum removal slag is mixed with a reducing agent, a slag-forming agent and an iron source and then reduced and smelted to obtain a tungsten-molybdenum-iron alloy.

[0009] Preferably, the oxidation roasting is carried out at a temperature of 500-600° C. and for a time of 2-5 hours.

[0010] Preferably, the reducing agent includes one or more of coke, silicon, aluminum and ferrosilicon, and the particle size of the reducing agent is 100-300 μm.

[0011] Preferably, the mass ratio of the oxidative molybdenum removal slag to the reducing agent is 100:5~19.8.

[0012] Preferably, the slag-forming agent includes potassium sulfate and / or lithium sulfate.

[0013] Preferably, the mass ratio of the oxidative molybdenum removal slag to the slag-forming agent is 100:2~10.

[0014] Preferably, the iron source includes one or more of iron particles, iron filings, scrap steel and steel filings.

[0015] Preferably, the mass ratio of the oxidative molybdenum removal slag to the iron source is 100:10~27.8.

[0016] Preferably, the reduction smelting is carried out in a protective atmosphere;

[0017] The reduction smelting includes first reduction smelting, heating and second reduction smelting;

[0018] The temperature of the first reduction smelting is 600-750°C, and the holding time is 15-40 minutes;

[0019] The temperature of the second reduction smelting is 1700-1850°C.

[0020] Preferably, the tungsten-molybdenum-iron alloy comprises, by mass fraction, 2.36-11.2% tungsten, 55-65% molybdenum, less than 1% silicon, less than 0.15% carbon, less than 0.1% sulfur, less than 0.5% copper, less than 0.05% phosphorus, less than 0.05% antimony, less than 0.06% tin and the remainder iron.

[0021] The present invention provides a method for recovering tungsten and molybdenum from tungsten smelting slag for removing molybdenum, comprising the following steps:

[0022] The molybdenum removal slag is subjected to oxidative roasting to obtain oxidized molybdenum removal slag;

[0023] The oxidative molybdenum removal slag is mixed with a reducing agent, a slag-forming agent and an iron source and then subjected to reduction smelting to obtain tungsten-molybdenum-iron.

[0024] The inventors of the present invention changed the traditional wet method of treating the molybdenum removal slag when recovering the tungsten and molybdenum in the molybdenum removal slag, and designed a process route for treating the molybdenum removal slag by pyrometallurgy, that is, firstly oxidizing and roasting the molybdenum removal slag, and then reducing and smelting the reducing agent, slag-making agent and iron source, and recovering the tungsten and molybdenum in the molybdenum removal slag in the form of tungsten-molybdenum-iron. The method of the present invention is simple, has few steps, and has a small loss of tungsten and molybdenum, thereby improving the recovery rate of tungsten and molybdenum, and solving the problem of low recovery rate of tungsten and molybdenum in the process of wet recovery of tungsten and molybdenum in the molybdenum removal slag due to lengthy process.

[0025] The recovery method of the present invention is suitable for recovering tungsten and molybdenum by removing molybdenum slag, and the recovery rate of tungsten and molybdenum is more than 95%.

[0026] Therefore, the present invention has the advantages of high efficiency and high metal recovery rate compared with the traditional wet extraction process.

[0027] The tungsten-molybdenum-iron alloy product obtained by the present invention has high purity and a wide range of applications, and can replace tungsten iron and molybdenum iron for steel smelting, thereby avoiding the problem of harsh conditions caused by adding in batches or directly adding.

[0028] The present invention recovers tungsten and molybdenum in the molybdenum removal slag in the form of tungsten-molybdenum-iron alloy, solves the problem of difficulty in separating tungsten and molybdenum, reduces production costs, realizes efficient and comprehensive utilization of the molybdenum removal slag, has a simple and easy process, and is suitable for industrial production.

[0029] Furthermore, the reducing agent, slag-forming agent and iron source selected in the present invention match the composition of the oxidative molybdenum removal slag, and efficiently recover tungsten and molybdenum in the tungsten smelting molybdenum removal slag to obtain a tungsten-molybdenum-iron alloy that meets market demand. DETAILED DESCRIPTION

[0030] The present invention provides a method for recovering tungsten and molybdenum from tungsten smelting slag for removing molybdenum, comprising the following steps:

[0031] The molybdenum removal slag is subjected to oxidative roasting to obtain oxidized molybdenum removal slag;

[0032] The oxidized molybdenum-removing slag is mixed with a reducing agent, a slag-forming agent and steel scraps and then subjected to reduction smelting to obtain a tungsten-molybdenum-iron alloy.

[0033] The present invention performs oxidative roasting on the molybdenum removal slag to obtain the oxidized molybdenum removal slag.

[0034] In the present invention, the molybdenum-removing slag preferably includes 40-65% of molybdenum sulfide by mass fraction. In a specific embodiment, the mass fraction of the molybdenum can be 40%, 45%, 50%, 55%, 60% or 65%.

[0035] In terms of mass fraction, the molybdenum-removing slag preferably includes 1.5-6.5% of tungsten trioxide. In a specific embodiment, the mass fraction of the tungsten trioxide can be 1.5, 2%, 3%, 4%, 5%, or 6.5%.

[0036] In terms of mass fraction, the molybdenum-removing slag preferably includes less than 2% Si. In a specific embodiment, the mass fraction of Si may be 0, 0.5%, 1%, 1.5% or 2%.

[0037] In terms of mass fraction, the molybdenum-removing slag preferably includes less than 0.1% phosphorus. In specific embodiments, the mass fraction of phosphorus may be 0%, 0.02%, 0.04%, 0.06%, 0.08% or 0.1%.

[0038] In terms of mass fraction, the molybdenum-removing slag preferably includes less than 0.1% tin. In a specific embodiment, the mass fraction of tin can be 0%, 0.02%, 0.04%, 0.06%, 0.08% or 0.1%.

[0039] In terms of mass fraction, the molybdenum-removing slag preferably includes less than 0.1% copper. In a specific embodiment, the mass fraction of copper may be 0%, 0.02%, 0.04%, 0.06%, 0.08% or 0.1%.

[0040] Measured by mass fraction, the molybdenum-removing slag preferably includes a residual amount of impurities; the impurities preferably include sodium sulfate.

[0041] In the present invention, the particle size of the molybdenum removal slag is preferably less than 100 μm. In a specific embodiment, the particle size of the molybdenum removal slag may be 10 μm, 20 μm, 40 μm, 60 μm, 80 μm or 100 μm.

[0042] In the present invention, the particle size of the reducing agent is preferably 100-300 μm. In a specific embodiment, the particle size of the molybdenum removal slag may be 120 μm, 170 μm, 180 μm, 220 μm, 260 μm or 300 μm.

[0043] In the present invention, the temperature of the oxidative roasting is preferably 500-600°C. In a specific embodiment, the temperature of the oxidative roasting may be 500°C, 520°C, 540°C, 560°C, 580°C or 600°C. The time is preferably 2-5h. In a specific embodiment, the time of the oxidative roasting may be 2h, 3h, 4h or 5h.

[0044] The purpose of oxidative roasting is to convert the molybdenum sulfides in the molybdenum-removing slag into molybdenum oxides.

[0045] After obtaining the oxidized molybdenum-removing slag, the present invention mixes the oxidized molybdenum-removing slag with a reducing agent, a slag-forming agent, and an iron source, and then performs reduction smelting to obtain a tungsten-molybdenum-iron alloy.

[0046] In the present invention, the mass ratio of the oxidized molybdenum removal slag to the reducing agent is preferably 100:5~19.8. In a specific embodiment, the mass ratio of the oxidized molybdenum removal slag to the reducing agent can be 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14, 100:15, 100:16, 100:17, 100:18, 100:19 or 100:19.8. The reducing agent preferably includes one or more of coke, silicon, aluminum and ferrosilicon. In the present invention, the mass content of silicon in the ferrosilicon is preferably 75%.

[0047] In the present invention, the mass ratio of the oxidized molybdenum removal slag to the slag forming agent is preferably 100:2-10. In a specific embodiment, the mass ratio of the oxidized molybdenum removal slag to the slag forming agent can be 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9 or 100:10. The slag forming agent preferably includes potassium sulfate and / or lithium sulfate.

[0048] In the present invention, the mass ratio of the oxidized molybdenum removal slag to the iron source is preferably 100:10 to 27.8. The iron source preferably includes one or more of scrap steel, iron filings, steel filings and iron particles. In a specific embodiment, the mass ratio of the oxidized molybdenum removal slag to the reducing agent can be 100:10, 100:11, 100:12, 100:13, 100:14, 100:15, 100:16, 100:17, 100:18, 100:19, 100:20, 100:21, 100:22, 100:23, 100:24, 100:25, 100:26, or 100:27.8.

[0049] In the present invention, the reduction smelting is carried out in a protective atmosphere; the reduction smelting preferably includes a first reduction smelting, a heating step and a second reduction smelting.

[0050] In the present invention, the heating rate to the temperature of the first reduction smelting is preferably 35-50°C / min. In a specific embodiment, the heating rate can be 35 / min, 40°C / min, 45°C / min or 50°C / min.

[0051] In the present invention, the temperature of the first reduction smelting is preferably 600-750°C. In a specific embodiment, the temperature of the first reduction smelting may be 600°C, 650°C, 700°C or 750°C. The holding time is preferably 15-40 minutes. In a specific embodiment, the holding time of the first reduction smelting may be 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes.

[0052] In the present invention, the heating rate is preferably 35-50°C / min. In a specific embodiment, the heating rate can be 35 / min, 40°C / min, 45°C / min or 50°C / min.

[0053] In the present invention, the temperature of the second reduction smelting is preferably 1700-1850°C. In a specific embodiment, the temperature of the first reduction smelting can be 1700°C, 1750°C, 1800°C or 1850°C.

[0054] The present invention has no particular limitation on the time of the second reduction smelting, as long as the molten pool used for the second reduction smelting is melted clear.

[0055] After the second reduction smelting, the present invention preferably cools, deslags and finishes the obtained mixture to obtain the tungsten-molybdenum-iron alloy.

[0056] In the present invention, the tungsten-molybdenum-iron alloy preferably includes, by mass fraction, 2.36-11.2% tungsten. In a specific embodiment, the mass fraction of the tungsten can be 2.36%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or 11.2%.

[0057] In terms of mass fraction, the tungsten-molybdenum-iron alloy preferably includes 55-65% molybdenum. In a specific embodiment, the mass fraction of the molybdenum can be 55%, 58%, 63% or 65%.

[0058] In terms of mass fraction, the tungsten-molybdenum-iron alloy preferably includes less than 1% silicon. In specific embodiments, the mass fraction of silicon may be 0%, 0.2%, 0.4%, 0.6%, 0.8% or 1%.

[0059] In terms of mass fraction, the tungsten-molybdenum-iron alloy preferably includes less than 0.15% carbon. In a specific embodiment, the mass fraction of silicon can be 0%, 0.5%, 0.1% or 0.15%.

[0060] In terms of mass fraction, the tungsten-molybdenum-iron alloy preferably includes less than 0.1% sulfur. In a specific embodiment, the mass fraction of sulfur can be 0%, 0.02%, 0.04%, 0.06%, 0.08% or 0.1%.

[0061] In terms of mass fraction, the tungsten-molybdenum-iron alloy preferably includes less than 0.5% copper. In a specific embodiment, the mass fraction of copper can be 0%, 0.1%, 0.2%, 0.3%, 0.4% or 0.5%.

[0062] In terms of mass fraction, the tungsten-molybdenum-iron alloy preferably includes less than 0.05% phosphorus. In a specific embodiment, the mass fraction of phosphorus can be 0%, 0.01%, 0.02%, 0.03%, 0.04% or 0.05%.

[0063] In terms of mass fraction, the tungsten-molybdenum-iron alloy preferably includes less than 0.05% antimony. In a specific embodiment, the mass fraction of the antimony can be 0%, 0.01%, 0.02%, 0.03%, 0.04% or 0.05%.

[0064] In terms of mass fraction, the tungsten-molybdenum-iron alloy preferably includes less than 0.06% tin. In a specific embodiment, the mass fraction of tin can be 0%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05% or 0.06%.

[0065] The tungsten-molybdenum-iron alloy preferably includes a balance of iron in terms of mass fraction.

[0066] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0067] Example 1

[0068] The molybdenum removal slag with a particle size of 70 μm (the sulfide content of molybdenum is 60.19wt%, the content of tungsten trioxide is 2.57wt%, the content of silicon is 1.61wt%, the content of phosphorus is 0.06wt%, the content of tin is 0.03wt%, the content of copper is 0.01wt%, and the balance is impurities such as sodium sulfate) is placed in a push plate kiln for oxidation roasting at 550℃ for 2h, and then the molybdenum removal slag, carbon powder, aluminum particles (particle size 180μm), potassium sulfate, and steel scraps (iron content is 98.73%, and the balance is impurities) after oxidation roasting are added to the mixer according to a mass ratio of 100:6.4:7.8:8:17.7 and mixed evenly. The mixed materials are added to the crucible of the medium frequency furnace, argon gas is introduced, and the temperature is raised to 600℃ at a rate of 40℃ / min and kept warm for 30min, and the heating is continued, and the temperature is raised to 1800℃ at a rate of 35℃ / min and kept warm until the molten pool of the medium frequency furnace is melted. Then it is cast out of the furnace, cooled, slag removed and finished to obtain tungsten-molybdenum-iron alloy.

[0069] After testing, the molybdenum content of the prepared tungsten-molybdenum-iron alloy is 60.23wt%, the tungsten content is 4.09wt%, the silicon content is 0.08wt%, the carbon content is 0.11wt%, and the copper content is less than 0.01wt%.

[0070] It has been calculated that the recovery rate of molybdenum is 95.18% and the recovery rate of tungsten is 95.31%.

[0071] Example 2

[0072] The molybdenum removal slag with a particle size of 60 μm (the sulfide content of molybdenum is 63.98wt%, the content of tungsten trioxide is 5.69wt%, the content of silicon is 1.5wt%, the content of phosphorus is 0.06wt%, the content of tin is 0.02wt%, the content of copper is 0.01wt%, and the balance is impurities such as sodium sulfate) is placed in a push plate kiln for oxidation roasting at 580°C for 2.5h, and then the molybdenum removal slag, aluminum particles (particle size 220μm), potassium sulfate, lithium sulfate, and steel scraps (iron content 98.73%, the balance is impurities) after oxidation roasting are added to the mixer according to a mass ratio of 100:19.3:3:2:16.5 and mixed evenly. The mixed materials are added to the crucible of the medium frequency furnace, argon is introduced, and the temperature is raised to 650°C at a rate of 40°C / min and kept warm for 25min, and then the heating is continued, and the temperature is raised to 1850°C at 38°C / min and kept warm until the molten pool of the medium frequency furnace is melted clear. Then it is cast out of the furnace, cooled, slag removed and finished to obtain tungsten-molybdenum-iron alloy.

[0073] After testing, the molybdenum content of the prepared tungsten-molybdenum-iron alloy is 60.18wt%, the tungsten content is 8.53wt%, the silicon content is 0.08wt%, the carbon content is 0.04wt%, and the copper content is less than 0.01wt%.

[0074] It has been calculated that the recovery rate of molybdenum is 95.26% and the recovery rate of tungsten is 95.60%.

[0075] Example 3

[0076] The molybdenum removal slag with a particle size of 75μm (the sulfide content of molybdenum is 52.62wt%, the content of tungsten trioxide is 1.52wt%, the content of silicon is 1.8%, the content of phosphorus is 0.08%, the content of tin is 0.02%, the content of copper is 0.01%, and the balance is impurities such as sodium sulfate) is placed in a push plate kiln for oxidation roasting at 500℃ for 3h, and then the molybdenum removal slag, ferrosilicon (silicon content is 75wt%, particle size is 150μm), lithium sulfate, and iron particles after oxidation roasting are added to the mixer according to the mass ratio of 100:14.3:3:12.23 and mixed evenly. The mixed materials are added to the crucible of the medium frequency furnace, nitrogen is introduced, and the temperature is raised to 700℃ at a rate of 45℃ / min and kept warm for 20min. Continue to heat, and heat to 1820℃ at a rate of 40℃ / min until the molten pool of the medium frequency furnace is melted. Then cast out of the furnace for cooling, slag removal and finishing to obtain tungsten-molybdenum-iron alloy.

[0077] After testing, the molybdenum content of the prepared tungsten-molybdenum-iron alloy is 60.31wt%, the tungsten content is 2.77wt%, the silicon content is 0.5wt%, the carbon content is 0.05wt%, and the copper content is less than 0.01wt%.

[0078] It has been calculated that the recovery rate of molybdenum is 95.09% and the recovery rate of tungsten is 95.20%.

[0079] Example 4

[0080] The molybdenum removal slag with a particle size of 70μm (the sulfide content of molybdenum is 44.67wt%, the content of tungsten trioxide is 1.45wt%, the content of silicon is 1.2%, the content of phosphorus is 0.07%, the content of tin is 0.02%, the content of copper is 0.01%, and the balance is impurities such as sodium sulfate) is placed in a push plate kiln for oxidation roasting at 500℃ for 3h, and then the molybdenum removal slag, ferrosilicon (silicon content is 75wt%, particle size is 150μm), potassium sulfate, and iron particles after oxidation roasting are added to the mixer according to the mass ratio of 100:12.2:3.4:10.3 and mixed evenly. The mixed materials are added to the crucible of the medium frequency furnace, nitrogen is introduced, and the temperature is raised to 700℃ at a rate of 45℃ / min and kept warm for 20min. Continue to heat, and heat to 1800℃ at a rate of 45℃ / min until the molten pool of the medium frequency furnace is melted. Then cast out of the furnace for cooling, slag removal and finishing to obtain tungsten-molybdenum-iron alloy.

[0081] After testing, the molybdenum content of the prepared tungsten-molybdenum-iron alloy is 60.09wt%, the tungsten content is 3.1wt%, the silicon content is 0.6wt%, the carbon content is 0.06wt%, and the copper content is less than 0.01wt%.

[0082] It has been calculated that the recovery rate of molybdenum is 95.29% and the recovery rate of tungsten is 95.36%.

[0083] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for recovering tungsten and molybdenum from tungsten smelting slag, characterized in that: The following steps are involved: The molybdenum removal slag is subjected to oxidative roasting to obtain oxidized molybdenum removal slag; The oxidative molybdenum removal slag is mixed with a reducing agent, a slag-forming agent and an iron source, and then subjected to reduction smelting to obtain a tungsten-molybdenum-iron alloy; The slag-forming agent includes potassium sulfate and / or lithium sulfate; Calculated by mass fraction, the tungsten-molybdenum-iron alloy includes: 2.36-11.2% tungsten, 55-65% molybdenum, less than 1% silicon, less than 0.15% carbon, less than 0.1% sulfur, less than 0.5% copper, less than 0.05% phosphorus, less than 0.05% antimony, less than 0.06% tin and the remainder iron.

2. The recycling method according to claim 1, characterized in that: The temperature of the oxidation roasting is 500-600° C., and the time is 2-5 hours.

3. The recycling method according to claim 1, characterized in that: The reducing agent includes one or more of coke, silicon, aluminum and ferrosilicon, and the particle size of the reducing agent is 100-300 μm.

4. The recovery method according to claim 1 or 3, characterized in that: The mass ratio of the oxidative molybdenum removal slag to the reducing agent is 100:5~19.

8.

5. The recycling method according to claim 1, characterized in that: The mass ratio of the oxidative molybdenum removal slag to the slag-forming agent is 100:2-10.

6. The recycling method according to claim 1, characterized in that: The iron source includes one or more of iron particles, iron filings and steel filings.

7. The recycling method according to claim 1 or 6, characterized in that: The mass ratio of the oxidative molybdenum removal slag to the iron source is 100:10~27.

8.

8. The recycling method according to claim 1, characterized in that: The reduction smelting is carried out in a protective atmosphere; The reduction smelting includes first reduction smelting, heating and second reduction smelting; The temperature of the first reduction smelting is 600-750°C, and the holding time is 15-40 minutes; The temperature of the second reduction smelting is 1700-1850°C.