A method for the comprehensive recovery of molybdenum metal from copper smelting slag

Abstract

This invention discloses a method for the comprehensive recovery of molybdenum metal from copper smelting slag. Addressing the challenges of complex molybdenum occurrence states, fine particle size, and difficulties in recovery using conventional methods, this invention proposes a combined process integrating mineral processing pre-enrichment with hydrometallurgical / pyrometallurgical methods. The method includes: crushing and grinding the copper smelting slag, followed by flotation to obtain a rough molybdenum concentrate; subjecting the rough molybdenum concentrate to oxidative roasting, acid leaching, and solvent extraction to obtain a high-purity molybdenum trioxide product. For different slag types, selective leaching of molybdenum can be achieved using an oxygen-pressure acid leaching process, or a smelting reduction process can be used to simultaneously recover iron and molybdenum to prepare iron-molybdenum alloys. This invention achieves highly efficient recovery of molybdenum resources from copper smelting slag, with a molybdenum recovery rate exceeding 95%, while simultaneously utilizing iron. It offers advantages such as flexible process flow, high metal recovery rate, and environmental friendliness, providing a new approach for the resource utilization of copper smelting slag.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for the comprehensive recovery of molybdenum metal from copper smelting slag. Background Technology

[0002] Copper smelting slag is a byproduct of copper pyrometallurgical processes, producing approximately 2-3 tons of slag for every ton of copper produced. Besides valuable elements such as copper, iron, and zinc, some copper smelting slag also contains 0.1%-0.5% molybdenum metal. Molybdenum is an important strategic rare metal, widely used in steel, petrochemical, and aerospace industries. However, due to the complex mineral composition and fine particle size of copper smelting slag, molybdenum often exists in oxide form, closely associated with or encapsulated by minerals such as fritillary olivine and magnetite, making it difficult to effectively recover using traditional single-benefit methods. Currently, large quantities of copper smelting slag are stockpiled or used as building materials, not only wasting molybdenum resources but also posing environmental pollution risks. Therefore, developing a method for the deep recovery of molybdenum metal from copper smelting slag is of great significance for achieving comprehensive resource utilization and alleviating pressure on primary molybdenum resources. Summary of the Invention

[0003] The purpose of this invention is to provide a method for the comprehensive recovery of molybdenum metal from copper smelting slag.

[0004] The objective of this invention is achieved by the method for comprehensively recovering molybdenum metal from copper smelting slag, which includes pretreatment, pre-enrichment, roasting, leaching, extraction separation, and post-treatment steps, specifically including: A. Pretreatment: The copper smelting slag to be treated is crushed and ground to obtain material a; B. Pre-enrichment: Material a is subjected to a process of "copper suppression and molybdenum flotation" or "copper-molybdenum mixed flotation separation" to obtain molybdenum rough concentrate b; C. Calcination: The crude molybdenum concentrate b is oxidized and roasted to obtain the roasted product c; D. Leaching: The roasted product is leached with an acidic leaching agent to obtain a molybdenum-containing leachate d; E. Extraction and separation: The molybdenum-containing leachate d is extracted with an amine extractant, and the loaded organic phase is washed and then back-extracted with ammonia to obtain a molybdenum-rich solution e. F. Post-processing: Neutralize and precipitate the molybdenum-rich solution e to obtain ammonium molybdate or polymolybdate, which is then calcined to obtain molybdenum trioxide product.

[0005] The specific steps are as follows: (1) Crushing and grinding: The copper smelting slag is crushed and then ground to fully dissociate the molybdenum minerals and gangue minerals in the slag.

[0006] (2) Flotation pre-enrichment: The grinding products are subjected to flotation using a "copper-suppressed molybdenum flotation" or "copper-molybdenum mixed flotation-separation" process to obtain molybdenum rough concentrate. During the flotation process, modifiers, inhibitors, collectors and frothers are added to achieve selective enrichment of molybdenum minerals.

[0007] (3) Roasting pretreatment: The molybdenum concentrate is oxidized and roasted to destroy the mineral structure, converting molybdenum into soluble oxides and iron oxides into insoluble hematite, thus creating favorable conditions for subsequent leaching.

[0008] (4) Leaching: The roasted product is leached with an acidic leaching agent to allow molybdenum to enter the leaching solution and achieve separation from gangue components.

[0009] (5) Extraction and separation: The molybdenum-containing leachate was solvent-extracted using an amine extractant (such as N235) to selectively extract molybdenum. The loaded organic phase was washed and then back-extracted with ammonia to obtain a molybdenum-rich solution.

[0010] (6) Precipitation and calcination: The molybdenum-rich solution is neutralized and precipitated to obtain ammonium molybdate or polymolybdate, which is then calcined to obtain high-purity molybdenum trioxide product.

[0011] As a preferred option, the flotation process described in step (2) adopts the process of "grinding - copper-molybdenum mixed flotation - regrinding of copper-molybdenum mixed concentrate - copper-molybdenum flotation separation", which can obtain molybdenum concentrate with a molybdenum grade of more than 25% and a recovery rate of more than 75%.

[0012] Preferably, the oxidation calcination temperature in step (3) is 600-800℃ and the calcination time is 1-3 hours.

[0013] As a preferred option, the extractant in step (5) is trialkylamine (N235). The pH value of the leachate is not adjusted during the extraction process, and the extraction efficiency can reach more than 94%. After three-stage countercurrent extraction, the molybdenum extraction rate can reach 99.26%.

[0014] For different slag types, this invention can also employ an oxygen-pressure acid leaching process to achieve selective leaching of molybdenum, or a molten reduction process to simultaneously recover iron and molybdenum to prepare iron-molybdenum alloys. The specific operation of the oxygen-pressure acid leaching process for selective molybdenum leaching is as follows: For copper smelting slag with high oxidation rate, oxygen pressure acid leaching is used to enhance molybdenum leaching.

[0015] Using high-oxidation-rate slag from a copper smelter as raw material, containing 0.42% Mo and 2.26% Cu, the processing procedure is as follows: 1. Fine grinding: Grind the slag to a particle size of -0.045mm, accounting for 95%.

[0016] 2. Oxygen-pressure acid leaching: The ground ore is placed in a high-pressure reactor, sulfuric acid is added, oxygen is introduced, and the temperature is controlled at 180-200℃, the oxygen partial pressure at 0.6-0.8 MPa, the liquid-to-solid ratio at 5:1, and the leaching time at 2-3 hours. Under these conditions, the molybdenum leaching rate reaches 95.39%, the copper leaching rate reaches 96.87%, and more than 90% of the iron enters the leaching residue (which can be used as a raw material for iron smelting).

[0017] 3. Solid-liquid separation: The leaching slurry is subjected to solid-liquid separation to obtain molybdenum-containing leaching solution and leaching residue.

[0018] 4. Solvent extraction: The leachate was extracted using the same N235 extraction system as in Example 1, and the molybdenum extraction rate reached over 99%.

[0019] 5. Back-extraction and product preparation: The supported organic phase is back-extracted with ammonia water, and the back-extraction solution is crystallized and calcined to obtain molybdenum trioxide product.

[0020] Its beneficial effects are as follows: by using oxygen pressure acid leaching technology, highly selective leaching of molybdenum and copper is achieved, while iron is retained in the slag, simplifying subsequent separation processes.

[0021] The specific operation of the molten reduction process for the simultaneous recovery of iron and molybdenum to prepare iron-molybdenum alloys is as follows: For molybdenum that is difficult to recover from flotation tailings through mineral processing, a pyrometallurgical reduction process is used to simultaneously recover iron and molybdenum.

[0022] The tailings from copper flotation in an electric arc furnace at a copper smelter were used as raw material. The tailings contained 35.37% Fe and 0.30% Mo. Iron mainly existed as magnetite and fir olivine, while molybdenum was primarily in oxide form and formed chemical bonds with silicon and iron. The processing procedure was as follows: 1. Ingredients: Mix copper slag with pulverized coal (reducing agent), calcium oxide and aluminum oxide (slag-forming agent) in a ratio of copper slag: pulverized coal: calcium oxide: aluminum oxide = 100: 20: 20: 10.

[0023] 2. Melt Reduction: The mixture is melt-reduced in a high-temperature furnace at 1400℃ for 60 minutes. Under these conditions, molybdenum and iron are reduced and enriched in the alloy phase.

[0024] 3. Separation: After smelting, the metal is naturally cooled and then crushed and separated to obtain an iron-molybdenum alloy and secondary slag.

[0025] 4. Product specifications: Fe recovery rate of 89.03% and Mo recovery rate of 98.44% in the iron-molybdenum alloy, Fe grade of 91.70% and Mo grade of 0.86%.

[0026] Its beneficial effects are as follows: the molten reduction process simultaneously recovers iron and molybdenum from copper slag to obtain iron-molybdenum alloy products, which solves the problem that conventional mineral processing methods are difficult to recover molybdenum in complex occurrence states.

[0027] This invention achieves efficient recovery of molybdenum resources from copper smelting slag, with a molybdenum recovery rate of over 95%, while simultaneously utilizing iron. It has advantages such as flexible process flow, high metal recovery rate, and environmental friendliness, providing a new approach for the resource utilization of copper smelting slag. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0030] The method for comprehensively recovering molybdenum metal from copper smelting slag according to the present invention includes pretreatment, pre-enrichment, roasting, leaching, extraction separation, and post-treatment steps, specifically including: A. Pretreatment: The copper smelting slag to be treated is crushed and ground to obtain material a; B. Pre-enrichment: Material a is subjected to a process of "copper suppression and molybdenum flotation" or "copper-molybdenum mixed flotation separation" to obtain molybdenum rough concentrate b; C. Calcination: The crude molybdenum concentrate b is oxidized and roasted to obtain the roasted product c; D. Leaching: The roasted product is leached with an acidic leaching agent to obtain a molybdenum-containing leachate d; E. Extraction and separation: The molybdenum-containing leachate d is extracted with an amine extractant, and the loaded organic phase is washed and then back-extracted with ammonia to obtain a molybdenum-rich solution e. F. Post-processing: Neutralize and precipitate the molybdenum-rich solution e to obtain ammonium molybdate or polymolybdate, which is then calcined to obtain molybdenum trioxide product.

[0031] In step A, crushing and grinding involves grinding the copper smelting slag to be processed to a thickness of -0.074 mm, accounting for more than 90%.

[0032] The roasting temperature described in step C is 600~800℃.

[0033] The roasting time described in step C is 1 to 3 hours.

[0034] The acidic leaching agent mentioned in step D is dilute sulfuric acid.

[0035] The leaching temperature in step D is 50~70℃, and the leaching time is 1~3h.

[0036] The amine extractant mentioned in step E consists of N235, a modifier, and sulfonated kerosene, wherein the modifier is an alkylamine.

[0037] The volume ratio of N235, modifier and sulfonated kerosene is (10~30):(10~30):(50~70).

[0038] The present invention will be further described below with reference to specific embodiments: Example 1

[0039] Using flash slag from a copper smelter as raw material, its main components include Cu 2.26%, Mo 0.42%, Fe 43.95%, and SiO2 30.51%. The processing procedure is as follows: 1. Grinding: Grind the slag to -0.074mm, accounting for 90%.

[0040] 2. Flotation pre-enrichment: The "copper suppression and molybdenum flotation" process is adopted. Under the condition of pulp pH=9, 200g / t of Na2S is added as a modifier, 150g / t of xanthate and 180g / t of kerosene are added as collectors, and 120g / t of No. 2 oil is added as a frother. Through a closed-circuit flotation process of roughing, scavenging and cleaning, molybdenum rough concentrate (Mo grade 1.90%, recovery rate 40.70%) and copper concentrate (Cu grade 34.80%, recovery rate 85.70%) are obtained.

[0041] 3. Oxidative roasting: The crude molybdenum concentrate is oxidized and roasted at 650℃ for 2 hours to convert molybdenum into soluble oxides.

[0042] 4. Acid leaching: The calcined sand was leached with dilute sulfuric acid at a liquid-to-solid ratio of 4:1 and a temperature of 60℃ for 2 hours, and the molybdenum leaching rate reached 85.86%.

[0043] 5. Solvent Extraction: The leachate consisted of an organic phase of 20% N235 + 20% modifier + 60% sulfonated kerosene. Extraction was performed for 20 minutes at a ratio of O / A = 1:1 and a temperature of 25°C. The single-stage extraction rate reached 94.35%, and the total extraction rate reached 99.26% after three-stage countercurrent extraction. The modifier was a primary amine, RNH2.

[0044] 6. Back-extraction and precipitation: The supported organic phase was subjected to three-stage countercurrent back-extraction with 8 mol / L ammonia water, with a back-extraction rate of 99.66%. The back-extraction solution was neutralized, precipitated, and calcined to obtain molybdenum trioxide product with a purity of 98.48%.

[0045] Example 2

[0046] Using flash slag from a copper smelter as raw material, its main components include Cu 2.32%, Mo 0.38%, Fe 42.81%, and SiO2 33.12%. The processing procedure is as follows: 1. Grinding: Grind the slag to a thickness of -0.074mm, accounting for 95%.

[0047] 2. Flotation pre-enrichment: The "copper-suppressing and molybdenum-floating" process is adopted. Under the condition of pulp pH=9, 150g / t of Na2S is added as a modifier, 100g / t of xanthate and 150g / t of kerosene are added as collectors, and 100g / t of No. 2 oil is added as a frother. Through a closed-circuit flotation process of roughing, scavenging and cleaning, molybdenum rough concentrate (Mo grade 1.92%, recovery rate 41.33%) and copper concentrate (Cu grade 35.23%, recovery rate 86.21%) are obtained.

[0048] 3. Oxidative roasting: The crude molybdenum concentrate is oxidized and roasted at 800℃ for 1 hour to convert molybdenum into soluble oxides.

[0049] 4. Acid leaching: The calcined sand was leached with dilute sulfuric acid at a liquid-to-solid ratio of 4:1 and a temperature of 60℃ for 2 hours, and the molybdenum leaching rate reached 86.33%.

[0050] 5. Solvent extraction: The leachate consists of an organic phase of 10% N235 + 10% modifier + 80% sulfonated kerosene. Extraction is carried out for 40 minutes at a ratio of O / A = 1:1 and a temperature of 20℃. The single-stage extraction rate reaches 93.82%, and the total extraction rate reaches 99.31% after three-stage countercurrent extraction. The modifier is a secondary amine.

[0051] 6. Back-extraction and precipitation: The supported organic phase was subjected to three-stage countercurrent back-extraction with 8 mol / L ammonia water, with a back-extraction rate of 99.72%. The back-extraction solution was neutralized, precipitated, and calcined to obtain molybdenum trioxide product with a purity of 98.89%.

[0052] Example 3

[0053] Using flash slag from a copper smelter as raw material, its main components include Cu 2.45%, Mo 0.56%, Fe 44.22%, and SiO2 31.17%. The processing procedure is as follows: 1. Grinding: Grind the slag to -0.074mm, accounting for 93%.

[0054] 2. Flotation pre-enrichment: The "copper-suppressing and molybdenum-floating" process is adopted. Under the condition of pulp pH=10, 250g / t of Na2S is added as a modifier, 180g / t of xanthate and 200g / t of kerosene are added as collectors, and 150g / t of No. 2 oil is added as a frother. Through a closed-circuit flotation process of roughing, scavenging and cleaning, molybdenum rough concentrate (Mo grade 1.96%, recovery rate 41.63%) and copper concentrate (Cu grade 35.13%, recovery rate 86.22%) are obtained.

[0055] 3. Oxidative roasting: The crude molybdenum concentrate is oxidized and roasted at 700℃ for 1.5 hours to convert molybdenum into soluble oxides.

[0056] 4. Acid leaching: The calcined sand was leached with dilute sulfuric acid at a liquid-to-solid ratio of 4:1 and a temperature of 70℃ for 1.5 hours, and the molybdenum leaching rate reached 86.23%.

[0057] 5. Solvent extraction: The leachate consists of an organic phase of 15% N235 + 15% modifier + 70% sulfonated kerosene. Extraction is carried out for 25 minutes at a ratio of O / A = 1:1 and a temperature of 28℃. The single-stage extraction rate reaches 95.31%, and the total extraction rate reaches 99.47% after three-stage countercurrent extraction. The modifier is a tertiary amine.

[0058] 6. Back-extraction and precipitation: The supported organic phase was subjected to three-stage countercurrent back-extraction with 8 mol / L ammonia water, with a back-extraction rate of 99.74%. The back-extraction solution was neutralized, precipitated, and calcined to obtain molybdenum trioxide product with a purity of 98.88%.

Claims

1. A method for the comprehensive recovery of molybdenum metal from copper smelting slag, characterized in that, The method for comprehensively recovering molybdenum metal from copper smelting slag includes pretreatment, pre-enrichment, roasting, leaching, extraction separation, and post-treatment steps, specifically including: A. Pretreatment: The copper smelting slag to be treated is crushed and ground to obtain material a; B. Pre-enrichment: Material a is subjected to a process of "copper suppression and molybdenum flotation" or "copper-molybdenum mixed flotation separation" to obtain molybdenum rough concentrate b; C. Calcination: The crude molybdenum concentrate b is oxidized and roasted to obtain the roasted product c; D. Leaching: The roasted product is leached with an acidic leaching agent to obtain a molybdenum-containing leachate d; E. Extraction and separation: The molybdenum-containing leachate d is extracted with an amine extractant, and the loaded organic phase is washed and then back-extracted with ammonia to obtain a molybdenum-rich solution e. F. Post-processing: Neutralize and precipitate the molybdenum-rich solution e to obtain ammonium molybdate or polymolybdate, which is then calcined to obtain molybdenum trioxide product.

2. The method for comprehensively recovering molybdenum metal from copper smelting slag according to claim 1, characterized in that, In step A, crushing and grinding involves grinding the copper smelting slag to be processed to a thickness of -0.074 mm, accounting for more than 90%.

3. The method for comprehensively recovering molybdenum metal from copper smelting slag according to claim 1, characterized in that, The roasting temperature described in step C is 600~800℃.

4. The method for comprehensively recovering molybdenum metal from copper smelting slag according to claim 1, characterized in that, The roasting time described in step C is 1 to 3 hours.

5. The method for comprehensively recovering molybdenum metal from copper smelting slag according to claim 1, characterized in that, The acidic leaching agent mentioned in step D is dilute sulfuric acid.

6. The method for comprehensively recovering molybdenum metal from copper smelting slag according to claim 1, characterized in that, The leaching temperature in step D is 50~70℃, and the leaching time is 1~3h.

7. The method for comprehensively recovering molybdenum metal from copper smelting slag according to claim 1, characterized in that, The amine extractant mentioned in step E consists of N235, a modifier, and sulfonated kerosene, wherein the modifier is an alkylamine.

8. The method for comprehensively recovering molybdenum metal from copper smelting slag according to claim 7, characterized in that, The volume ratio of N235, modifier and sulfonated kerosene is (10~30):(10~30):(50~70).

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