Method for synergistically and intensively leaching molybdenum from ferromolybdenum smelting smoke dust under normal temperature condition

Abstract

The invention provides a synergistic enhanced leaching method for efficiently extracting molybdenum from ferromolybdenum smelting smoke dust under the condition of normal temperature. By introducing hypochlorite ions into a sodium hydroxide segmented leaching system, the leaching efficiency of molybdenum is effectively improved. According to the method, aiming at the characteristics that the content of impurities in the ferromolybdenum smelting smoke is high and insoluble salts such as lead molybdate are easily formed on the surface of molybdenum oxide, sodium hydroxide is used for dissolving salt coverings, meanwhile, hypochlorite ions can promote low-valence compounds (molybdenum disulfide and molybdenum dioxide) of molybdenum to be oxidized and dissolved in alkali, and efficient leaching of molybdenum is promoted. Besides, in the leaching process, impurity metal reacts with sodium hydroxide to generate hydroxide precipitates, so that dissolution of impurity metal ions is reduced, the extraction rate of molybdenum is increased, and the difficulty of follow-up purification treatment is reduced. The method is suitable for the field of comprehensive resource recovery, and resource utilization of the ferromolybdenum smelting smoke dust is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of mineral resource recovery, and in particular relates to a method for synergistically enhancing the leaching of molybdenum from ferromolybdenum smelting dust at room temperature, which can effectively recover the molybdenum in the ferromolybdenum smelting dust. Background Art

[0002] The color of ferromolybdenum smelting dust is light yellow-brown, with extremely fine particles, earthy or powdery. It is the precipitate of the flying dust from ferromolybdenum smelting after water washing. In addition to a certain amount of molybdenum, it also contains a large amount of quartz, silicate, iron, copper, calcium, magnesium, aluminum, lead, etc. At present, the utilization of ferromolybdenum smelting dust is mainly returned to the ferromolybdenum oxide molybdenum batching system as raw material, but because the dust particle size is too fine, its utilization efficiency is not high after returning to the batching system, and most of it is still consumed in the form of ash from the smelting system, causing energy waste; another existing utilization method is to use alkali roasting-water leaching-ion exchange or extraction process to recover molybdenum and produce molybdate. The main process of this method is to convert molybdenum oxide, insoluble heavy metal iron molybdate, calcium molybdate, etc. in molybdenum-containing waste into sodium molybdate through soda ash, and then transfer molybdate to aqueous solution through crushing, grinding and water leaching, and then recover molybdenum through ion exchange (extraction) or chemical precipitation. The recovery rate of molybdenum in this method is only about 82%. At the same time, the waste gas generated during the roasting process and the pollution generated during the leaching process are difficult to control. Therefore, it is necessary to establish a new, efficient and environmentally friendly molybdenum ferrometallurgical dust utilization process.

[0003] Patents CN101280369A and CN101724758A both involve methods for recovering molybdenum from molybdenum-containing waste catalysts. Patent CN101280369A roasts and crushes the waste catalyst, then uses an alkaline solution for leaching and filtering, and after multiple roasting and acidification treatments, the molybdenum is precipitated in the form of molybdic acid, and finally an ammonium molybdate product is obtained. Patent CN101724758A roasts and crushes the waste catalyst, then adds an alkaline substance for mixed roasting, and then leaches with a mixed acid solution to finally obtain an ammonium molybdate product. Both methods are complex and have high processing costs.

[0004] Patent CN102950010A discloses a method for utilizing molybdenum in waste cobalt-molybdenum sulfur-resistant conversion catalysts, and the specific steps are to use an alkaline aqueous solution of potassium to react with waste cobalt-molybdenum sulfur-resistant conversion catalysts, convert the molybdenum contained therein into a water-soluble powder material, directly use it as an active component raw material for preparing sulfur-resistant conversion catalysts, and prepare cobalt-molybdenum sulfur-resistant conversion catalyst products, including crushing, preparation of water-soluble powders, and preparation steps of cobalt-molybdenum sulfur-resistant conversion catalyst products. However, molybdenum in ferromolybdenum smelting dust exists in the form of multiple valence states. When only potassium hydroxide is used as a leaching agent, although PbMoO4 and MoO3 in the dust can be dissolved by KOH solution, they are wrapped in MoO2 and MoS2 and are insoluble in potassium hydroxide solution. If the two cannot be oxidized into alkali-soluble MoO3, MoO2 and MoS2 will be retained in the leached residue after leaching, and the leaching rate of molybdenum in ferromolybdenum smelting dust is low. Therefore, the above method is not suitable for the recovery of molybdenum in ferromolybdenum smelting dust.

[0005] Patent CN117701918A discloses a method for recovering molybdenum from ferromolybdenum smelting dust, which includes oxidizing and roasting the ferromolybdenum smelting dust and then adding reagents for alkaline leaching to increase the molybdenum leaching rate and reduce the burden of the purification process. However, this patent requires high-temperature roasting of up to 600-670°C, and the process equipment and comprehensive cost have no significant advantages. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art and solve the problem of recovering molybdenum resources in ferromolybdenum smelting dust, the purpose of the present invention is to provide a method for synergistically enhanced leaching of molybdenum from ferromolybdenum smelting dust under normal temperature conditions. After segmented-oxidation synergistic enhanced leaching, the recovery effect of molybdenum resources is significant.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for synergistically enhancing the leaching of molybdenum from ferromolybdenum smelting dust under normal temperature conditions comprises the following steps:

[0009] Step 1, the synergistic enhanced leaching step, is divided into two stages of leaching, wherein:

[0010] Stage I leaching: Add water to the ferromolybdenum smelting dust to adjust the slurry to 30% to 50% by weight concentration, then add sodium hydroxide and stir to leach at room temperature;

[0011] Stage II leaching: Add sodium hypochlorite to the stage I leaching product and continue stirring and leaching at room temperature;

[0012] Step 2, solid-liquid separation step, separates the product after leaching into solid and liquid, and the filtrate is the molybdenum-rich noble liquid.

[0013] In one embodiment, the molybdenum in the ferromolybdenum smelting smoke exists in one or more forms of MoS2, MoO2, MoO3 and MeMoO4 (Me: Pb, Fe, Cu, Ca, Ni, Zn, etc.).

[0014] In one embodiment, the room temperature condition is 20-30°C.

[0015] In one embodiment, in step 1, the liquid-to-solid ratio of the slurry is controlled between 2.3:1 and 1:1 by weight.

[0016] In one embodiment, in the stage I leaching, the initial addition amount of the leaching agent sodium hydroxide is 200 g / L to 300 g / L, and the added reagent sodium hydroxide content is 98.5%.

[0017] In one embodiment, in the stage II leaching, the initial amount of sodium hypochlorite added is 40 g / L to 50 g / L, and the content of sodium hypochlorite in the added reagent is 99.7%.

[0018] In one embodiment, the leaching time of stage I is controlled at 3h to 5h.

[0019] In one embodiment, the leaching time of stage II is controlled within 1 hour to 3 hours.

[0020] The present invention adopts sodium hydroxide aqueous solution to react with molybdenum iron smelting smoke to carry out stage I leaching, open the salt substances on the surface of the smoke, dissolve molybdenum flower and salt substances such as lead molybdate into the leaching solution, then add sodium hypochlorite to carry out stage II leaching, oxidize tetravalent molybdenum in alkali-insoluble compounds such as MoO2 and MoS2 into hexavalent molybdenum, synergistically enhance their alkali solubility, dissolve more molybdenum in the solution, and obtain molybdenum-rich precious liquid at the end of leaching.

[0021] Compared with the prior art, the present invention does not require high-temperature roasting. Under normal temperature conditions, sodium hydroxide and sodium hypochlorite are used to synergistically enhance leaching in stages, and molybdenum-rich precious liquid can be obtained after solid-liquid separation. This can reduce reagent consumption, shorten leaching time, and achieve efficient recovery of molybdenum. This allows comprehensive utilization of ferromolybdenum smelting dust, which is in line with the resource sustainable development strategy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a process flow chart of the present invention.

[0023] Figure 2 It is the process flow chart of Comparative Example 1 of the present invention.

[0024] Figure 3 It is a process flow chart of Example 1 of the present invention.

[0025] Figure 4 It is the process flow chart of Comparative Example 2 of the present invention.

[0026] Figure 5 It is a process flow chart of Example 2 of the present invention. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0028] The molybdenum iron smelting dust of the present invention is a molybdenum-containing waste generated from the production process of molybdenum iron, and molybdenum exists in the form of multiple physical phases, such as MoS2, MoO2, MoO3 and MeMoO4 (Me: Pb, Fe, Cu, Ca, Ni, Zn, etc.), and the content of molybdenum hua (MoO3) is relatively high. As mentioned above, the prior art is mainly aimed at the comprehensive recovery of secondary resources of molybdenum for ore dressing tailings, waste molybdenum-containing catalysts, waste molybdenum-containing alloys, etc., while there is little research on the comprehensive recovery of valuable metals of molybdenum in smelting dust. CN117701918A recovers molybdenum in smelting dust, but requires high-temperature roasting. Thus, the present invention provides a method for synergistically strengthening the leaching of molybdenum from molybdenum iron smelting dust under normal temperature conditions, which not only adds a new source for the recovery of molybdenum resources, but also solves the problem of recovering molybdenum in molybdenum iron smelting dust, realizes the resource recovery of molybdenum iron smelting dust, and reduces environmental risks.

[0029] like Figure 1 As shown, the present invention mainly comprises the following steps:

[0030] (1), Stage I leaching.

[0031] The ferromolybdenum smelting dust contains unrecovered molybdenum, which mainly exists in the form of insoluble molybdate, molybdenum flower and molybdenum disulfide. This step is mainly to open the salt substance package on the surface of the dust and dissolve the salt substances such as molybdenum flower and lead molybdate. The main reaction formula is as follows:

[0032] PbMoO4+2NaOH=Na2MoO4+Pb(OH)2↓

[0033] MeMoO4+2NaOH=Na2MoO4+Me(OH)2↓(Me:Pb, Fe, Cu, Ca, Ni, Zn, etc.)

[0034] MoO3+2NaOH=Na2MoO4+H2O

[0035] In the present invention, the ferromolybdenum smelting smoke can be placed in a stirring tank and prepared into a slurry. The liquid-solid ratio of the slurry is controlled between 2.3:1 and 1:1 by weight. Sodium hydroxide is used as a leaching agent, and its main function is to open the salt substance wrapping on the surface of the smoke, convert the insoluble molybdenum salt on the surface of the smoke into Na2MoO4 and dissolve it in the aqueous solution. Impurities such as lead, copper, iron, nickel, and zinc form hydroxides and enter the slag, which can remove the impurity ions in the solution. Among them, the leaching temperature can be controlled at 20 to 30°C, and the leaching time can be controlled at 3 to 5 hours. Based on the weight of the ferromolybdenum smoke, the amount of sodium hydroxide added is generally 250 to 270 g / L.

[0036] In this step, the ferromolybdenum smelting smoke is leached in a system with sodium hydroxide as a leaching agent. The sodium hydroxide can open the salt substances on the surface of the smoke and convert molybdenum into Na2MoO4 to dissolve in the aqueous solution. At the same time, it can remove the impurity ions in the solution and prevent the impurity ions from forming molybdate precipitation.

[0037] (2), Stage II leaching.

[0038] Sodium hypochlorite reagent is added to the slurry after stage I leaching, and stirred for oxidation alkaline leaching. The main equation is as follows:

[0039] MoS2+9NaClO+6NaOH=Na2MoO4+2Na2SO4+9NaCl+3H2O

[0040] MoO2+NaClO+2NaOH=Na2MoO4+NaCl+H2O

[0041] In the present invention, sodium hypochlorite is added after the completion of stage I leaching to carry out stage II leaching, so as to promote the oxidation and dissolution of low-valent oxides of molybdenum (MoO2 and MoS2) that are insoluble in alkali in alkali, and synergistically strengthen the leaching of molybdenum. The alkali that can be used is generally a strong alkali, such as sodium hydroxide or potassium hydroxide. Among them, the leaching temperature can be controlled at 20 to 30°C, and the leaching time can be controlled at 1 to 3 hours. Based on the weight of molybdenum iron dust, the amount of sodium hydroxide added is generally 40 to 50 g / L.

[0042] In this step, the ferromolybdenum smelting dust after the first stage of sodium hydroxide leaching is oxidized and leached in a system of sodium hydroxide + sodium hypochlorite as a leaching agent. Sodium hypochlorite can oxidize the low-valent molybdenum compounds of MoO2 and MoS2 that are insoluble in alkali into high-valent molybdenum compounds that are soluble in alkali. At the same time, under normal temperature conditions, sodium hypochlorite can avoid the cations formed by the oxidation of base metal sulfides and MoO4 2- Molybdate precipitation is generated, allowing more molybdenum to be recovered.

[0043] (3), solid-liquid separation.

[0044] After leaching, solid-liquid separation is carried out, and the filtrate is a molybdenum-containing noble liquid (Na2MoO4).

[0045] In summary, the present invention leaches the molybdenum iron smelting dust in two stages in a system of sodium hydroxide and sodium hydroxide + sodium hypochlorite as leaching agents. In the first stage, the salt substances wrapped on the surface of the dust can be opened and the soluble molybdenum compounds can be leached to remove the impurity ions in the solution. In the second stage, the sodium hypochlorite promotes the reaction of sodium hydroxide with MoO2 and MoS2, oxidizes the alkali to leach the insoluble molybdenum, and strengthens the conversion of molybdenum into Na2MoO4 to dissolve in the aqueous solution, which can reduce the consumption of reagents, shorten the leaching time, and better realize the efficient recovery of molybdenum resources.

[0046] The following are several specific embodiments of the present invention.

[0047] An experiment on recovering molybdenum from ferromolybdenum smelting dust was conducted at a molybdenum company in Shaanxi.

[0048] Comparative Example 1: Conventional Leaching

[0049] like Figure 2 As shown, 200.0 g of ferromolybdenum smelting dust was weighed and placed in a stirring tank, water was added to form a slurry, the liquid-solid ratio of the slurry was controlled at 1.5:1, 380 g / L of NaOH was added, and leaching was carried out at a temperature of 25°C for 8 hours.

[0050] Embodiment 1: The method of the present invention, such as Figure 3 As shown, the following steps are included:

[0051] Step 1: Synergistically enhanced leaching

[0052] Stage I leaching: Weigh 200.0g of ferromolybdenum smelting dust and place it in a stirring tank, add water to make slurry, control the slurry liquid-to-solid ratio at 1.5:1, add 260g / L NaOH, and leach at 25°C for 4h.

[0053] Leaching stage II: Add 42 g / L NaClO to leaching stage I and leach for 2 h at 25 °C.

[0054] Step 2, solid-liquid separation.

[0055] The test results are shown in the following table:

[0056]

[0057] The present invention adopts a resource comprehensive recovery process of coordinated leaching under the condition that the fineness of molybdenum iron smelting dust meets the conditions, and the leaching rate of molybdenum reaches 97.13%. Compared with the conventional leaching process, the leaching rate of molybdenum is increased by 6.72%, and the efficient recovery of molybdenum resources is realized. The process utilizes the advantages of coordinated enhanced leaching, reduces the consumption of reagents, shortens the leaching time, and greatly improves the leaching rate of molybdenum. It is a low-cost and high-recovery molybdenum recovery process, which helps to realize the sustainable development strategy of resources.

[0058] An experiment was conducted to recover molybdenum from ferromolybdenum smelting dust of a Chinese molybdenum company.

[0059] Comparative Example 2: Conventional Leaching

[0060] like Figure 4 As shown, 500.0 g of ferromolybdenum smelting dust was weighed and placed in a stirring tank, water was added to form a slurry, the liquid-solid ratio of the slurry was controlled at 1.5:1, 400 g / L of NaOH was added, and leaching was carried out at a temperature of 25°C for 8 hours.

[0061] Embodiment 2: The method of the present invention, such as Figure 5 As shown, the following steps are included:

[0062] Step 1: Synergistically enhanced leaching

[0063] Stage I leaching: Weigh 500.0g of ferromolybdenum smelting dust and place it in a stirring tank, add water to make slurry, control the slurry liquid-to-solid ratio at 1.5:1, add 265g / L NaOH, and leach at 25°C for 4h.

[0064] Leaching stage II: Add 45 g / L NaClO to leaching stage I and leach for 2 h at 25 °C.

[0065] Step 2, solid-liquid separation, the test results are as follows:

[0066]

[0067] The present invention adopts a comprehensive resource recovery process of synergistic enhanced leaching under the condition that the fineness of molybdenum iron smelting dust meets the conditions, and the leaching rate of molybdenum reaches 97.41%. Compared with the conventional leaching process, the leaching rate of molybdenum is increased by 5.82%, and the efficient recovery of molybdenum resources is achieved. The process utilizes the advantages of synergistic enhanced leaching, reduces the consumption of reagents, shortens the leaching time, and greatly improves the leaching rate of molybdenum. It is a low-cost and high-recovery molybdenum recovery process, which helps to realize the sustainable development strategy of resources.

[0068] The above description is only a preferred embodiment of the invention. It should be pointed out that those skilled in the art can make changes and modifications to the invention without departing from the spirit and scope of the invention, and all changes and modifications should be within the scope defined by the appended claims of the invention.

Claims

1. A method for synergistically enhancing the leaching of molybdenum from ferromolybdenum smelting dust at room temperature, characterized in that: The steps include: Step 1, the synergistic enhanced leaching step, is divided into two stages of leaching, wherein: Stage I leaching: Add water to the ferromolybdenum smelting dust to make a slurry, then add sodium hydroxide and stir to leach at room temperature; Stage II leaching: Add sodium hypochlorite to the stage I leaching product and continue stirring and leaching at room temperature; Step 2, solid-liquid separation step, separates the product after leaching into solid and liquid, and the filtrate is the molybdenum-rich noble liquid.

2. The method for synergistically enhancing leaching of molybdenum from ferromolybdenum smelting dust at room temperature according to claim 1, characterized in that: The molybdenum in the ferromolybdenum smelting smoke exists in one or more forms of MoS2, MoO2, MoO3 and MeMoO4, wherein Me is Pb, Fe, Cu, Ca, Ni or Zn.

3. The method for synergistically enhancing leaching of molybdenum from ferromolybdenum smelting dust at room temperature according to claim 1, characterized in that: The weight concentration of the ore pulp is 30% to 50%.

4. The method for synergistically enhancing leaching of molybdenum from ferromolybdenum smelting dust at room temperature according to claim 1 or 3, characterized in that: In the step 1, the liquid-to-solid ratio of the slurry is controlled between 2.3:1 and 1:1 by weight.

5. The method for synergistically enhancing leaching of molybdenum from ferromolybdenum smelting dust at room temperature according to claim 1, characterized in that: The normal temperature condition is 20-30°C.

6. The method for synergistically enhancing leaching of molybdenum from ferromolybdenum smelting dust at room temperature according to claim 1, characterized in that: In the first stage leaching, the initial addition amount of the leaching agent sodium hydroxide is 200 g / L to 300 g / L, and the added reagent sodium hydroxide content is 98.5%.

7. The method for synergistically enhancing leaching of molybdenum from ferromolybdenum smelting dust at room temperature according to claim 1, characterized in that: In the stage II leaching, the initial amount of sodium hypochlorite added is 40 g / L to 50 g / L, and the content of sodium hypochlorite in the added reagent is 99.7%.

8. The method for synergistically enhancing leaching of molybdenum from ferromolybdenum smelting dust at room temperature according to claim 1, characterized in that: The leaching time of stage I is controlled within 3 hours to 5 hours.

9. The method for synergistically enhancing leaching of molybdenum from ferromolybdenum smelting dust at room temperature according to claim 1, characterized in that: The leaching time of the stage II is controlled within 1 hour to 3 hours.

10. The method for synergistically enhancing leaching of molybdenum from ferromolybdenum smelting dust at room temperature according to claim 1, characterized in that: The molybdenum content of the molybdenum-rich noble liquid is not less than 100g / L.

Images