A method for enriching molybdenum from low-grade uranium-molybdenum ore

Abstract

The application discloses a method for enriching molybdenum from low-grade uranium-molybdenum ore, and belongs to the technical field of ore dressing. In view of the problems of high oxidation degree, micro-fine-grained embedding and low efficiency of traditional ore dressing and smelting of the low-grade uranium-molybdenum ore, the application proposes a collaborative process of'stage grinding-magnetic separation-oxidation-sulfur mixed flotation'. By pre-screening and rod grinding to control the particle size, the mineral over-grinding and mud phenomenon are reduced, and the maximum particle size for suitable flotation and magnetic separation is realized; the brown iron ore carrier is directionally enriched by combining with the super-strong magnetic field magnetic separation, and the clay gangue is removed; the synchronous recovery of oxidized molybdenum and molybdenum sulfide is realized by adopting a composite collector and a staged flotation strategy. The application has the advantages of simple process, high product recovery rate, convenient operation, low production cost and the like, and realizes efficient ore dressing and enrichment of the low-grade uranium-molybdenum ore.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology for radioactive associated minerals, specifically relating to a mineral processing method for enriching molybdenum from low-grade uranium-molybdenum ore. Background Technology

[0002] Associated uranium deposits constitute a certain proportion of uranium resources. Uranium and molybdenum share similar chemical properties, thus they often occur naturally as associated minerals. In recent years, with the continuous development and utilization of uranium and molybdenum resources in my country, high-grade uranium-molybdenum ore resources that are easy to process and have low production costs have been largely depleted, making low-grade uranium-molybdenum ore resources a promising research subject. Currently, the main method of developing and utilizing uranium-molybdenum ore in my country is direct hydrometallurgical processing of raw ore, including concentrated acid leaching, pressurized oxygen leaching, conventional stirred acid leaching, and conventional stirred alkaline leaching. The choice of development and utilization method mainly depends on the ore properties such as grade, particle size distribution, and degree of oxidation of the uranium-molybdenum ore.

[0003] One type of low-grade uranium-molybdenum deposit is a medium-to-low temperature hydrothermal porphyry uranium-molybdenum deposit. The ore has complex properties, high clay mineral content, high oxidation degree, and fine-grained, amorphous molybdenum-bearing minerals. The main molybdenum-bearing minerals in the ore are limonite, molybdenite-calcium ore, and uranium-molybdenite. The gangue minerals are mainly quartz, clay minerals, and feldspar. Molybdenum is partly present in limonite as molybdenum oxide, and partly in the form of molybdenite-calcium ore, uranium-molybdenite, azurite, and sulphite.

[0004] Current hydrometallurgical processes cannot achieve efficient and economical recovery of such low-grade uranium-molybdenum ores, mainly because: 1) the raw ore grade is low, resulting in high costs and low economic benefits from direct hydrometallurgical processing; 2) this typical low-grade uranium-molybdenum ore has a high content of fine-grained minerals, making solid-liquid separation difficult; 3) the pressure oxygen leaching process for the raw ore has a small capacity, requiring a large oxygen pressure reactor and related supporting equipment, leading to high equipment investment; 4) conventional stirred leaching has a low leaching rate and low resource utilization. Therefore, it is necessary to achieve efficient enrichment and recovery by beneficiation and the removal of a large amount of gangue minerals.

[0005] CN117443567A discloses a physical beneficiation and enrichment method for high-clay, low-grade uranium-molybdenum ore. This method involves adding a dispersant during grinding to enhance mineral particle separation, screening the grinding product into multiple particle sizes, and performing targeted sorting based on the differences in mineral properties within each size size. CN117737477A discloses a method for extracting uranium and molybdenum from encapsulated uranium-molybdenum ore. This method involves magnetically separating the encapsulated uranium-molybdenum ore under a magnetic field strength of 2T or higher to obtain magnetic concentrate and tailings. The magnetic concentrate undergoes a first-stage oxidative acid leaching to obtain a first-stage leachate. The first-stage leachate and the magnetic tailings are mixed for a second-stage oxidative acid leaching to obtain a uranium-molybdenum leachate. CN119287180A discloses a method for processing easily mud-encapsulated uranium-bearing primary molten molybdenum ore. The method involves coarsely crushing and finely crushing the easily mud-encapsulated uranium-bearing primary molten molybdenum ore, followed by a first-stage classification to obtain a first-stage fine mud and a first-stage material. The first-stage material is then coarsely ground and subjected to a second-stage classification to obtain a second-stage fine mud and a second-stage material. The second-stage material is then finely ground to obtain finely ground material. The first-stage fine mud, the second-stage fine mud, and the finely ground material obtained in step (1) are placed in an alkaline solution and pressurized under an oxygen-containing atmosphere for positive pressure alkaline leaching. The alkaline solution is an aqueous solution of alkali metal hydroxide, and the pH of the positive pressure alkaline leaching stage is controlled above 10. Subsequently, solid-liquid separation is performed to obtain molybdenum-rich leaching solution and uranium-rich leaching residue. The uranium-rich leaching residue obtained in step (2) is then subjected to acid leaching to obtain uranium-rich leaching solution.

[0006] While these existing technologies offer solutions for certain uranium-molybdenum ores, these solutions are difficult to apply to low-grade uranium-molybdenum ores. The primary target minerals in the beneficiation of these low-grade uranium-molybdenum ores are molybdenite and oxidized molybdenite. Due to the unique surface properties and occurrence states of these minerals, traditional single-process beneficiation methods are insufficiently adaptable. The main technical challenges in beneficiation are: 1) Mineral surface properties are unfavorable for flotation. Molybdenite: Its surface has a colloidal or amorphous structure, with significantly weaker hydrophobicity than molybdenite, making it difficult to effectively adsorb by conventional nonpolar hydrocarbon collectors. The surface is easily oxidized or adsorbed with slime, forming a hydrophilic layer that hinders contact between the collector and the mineral surface. Oxidized molybdenite (such as calcium molybdenite CaMoO4): Its surface is highly hydrophilic, with extremely poor natural floatability, making it impossible to directly bind with conventional collectors through physical adsorption. Chemical activation (such as sulfidation treatment) is needed to restore hydrophobicity, or traditional hydrocarbon acid collectors can be used, but the selectivity is poor, resulting in very low-grade concentrates and still high metallurgical costs.

[0007] 2) The minerals are found in complex states, exhibiting fine-grained dissemination, which hinders effective liberation. Process mineralogy reveals that molybdenite is closely associated with clay minerals, iron oxides, or uranium minerals, while molybdenite oxide is mostly intercalated with carbonate or silicate gangue, making it difficult to achieve individual liberation through conventional grinding. Both types of minerals are often dispersed in the ore as micron or nano-sized particles and are easily encapsulated by gangue minerals or form a "sludge cap," reducing separation efficiency.

[0008] In order to develop and utilize the aforementioned low-grade uranium-molybdenum ores, it is urgent to develop a systematic method that can achieve dual harvesting of sulfide and oxide minerals through mineral surface modification, customized reagent systems, and multi-process synergy, thereby increasing the grade of ore entering the metallurgical process, reducing production costs, and realizing the efficient and economical utilization of such low-grade uranium-molybdenum ores. Summary of the Invention

[0009] The purpose of this invention is to provide a method for enriching molybdenum from low-grade uranium-molybdenum ore. Addressing the challenges of coexistence of molybdenum sulfide and oxidized molybdenum ore, and the complex mineral occurrence states that hinder effective liberation, this invention develops a targeted flotation composite collector and provides a beneficiation and enrichment process based on this collector, thereby improving the grade and recovery rate of low-grade uranium-molybdenum ore. This objective is achieved through the following technical solutions.

[0010] A method for enriching molybdenum from low-grade uranium-molybdenum ore includes the following steps: S1 crushes the uranium-molybdenum ore to a particle size of less than 2 mm; S2 The uranium-molybdenum ore crushed in step S1 is screened using a 0.074~0.2mm grading screen. The undersize ore directly enters the magnetic separation process. The oversize ore is ground using a rod mill. The particle size of the ground ore is more than 95% of the undersize portion of the grading screen. S3 combines the screened ore obtained in step S2 with the ground ore, adds water to prepare a slurry, and performs magnetic separation to obtain magnetic concentrate and magnetic tailings. S4. The magnetic tailings obtained in step S3 are used to prepare a flotation slurry, and a composite flotation reagent is added for flotation to obtain a flotation concentrate. The composite flotation reagent includes 2000~3500 g / t of flotation dispersant, 100~250 g / t of flotation composite collector and 30~40 g / t of flotation frother. The flotation dispersant is a mixed solution of sodium carbonate and sodium silicate. The composition of the flotation composite collector is: 30~40 wt% ethyl biflavonoid, 10~20 wt% polyoxybutenol dithiophosphate ammonium, 20~30 wt% oxidized paraffin soap, 10~20 wt% RA935 (purchased from Hubei Chengfeng Chemical Co., Ltd.) and 10~20 wt% sulfonated kerosene. The flotation frother is selected from one or more of pine oil, MIBC (methyl isobutyl methanol) and 2-octanol. S5 combines the magnetic concentrate obtained in step S3 with the flotation concentrate obtained in step S4, and then thickens and filters them to obtain the molybdenum concentrate product.

[0011] This invention provides a method for enriching molybdenum from low-grade uranium-molybdenum ore. By developing a targeted flotation composite collector, and through the dual collecting action of sulfide and oxide minerals, a chemical regulation mechanism for the co-flotation interface of molybdenum oxide and molybdenum sulfide minerals is constructed under a flotation pulp system with strong inhibition and strong collection. This overcomes the technical challenge of simultaneous recovery of oxygen, sulfur and molybdenum minerals in high clay systems.

[0012] Furthermore, the low-grade uranium-molybdenum ore has a molybdenum grade of 0.1~0.3wt%, an oxidation rate of ≥50%, and a clay content of ≥25wt%.

[0013] Furthermore, in step S2, the rod mill is filled with steel rod media at a filling rate of 30-40%. By limiting the steel rod filling rate, the over-grinding of the ore is effectively controlled, increasing the proportion of intermediate particles suitable for magnetic separation / flotation by more than 15%, while reducing the generation of ultrafine particles below 0.074mm, significantly improving the rheological properties of the slurry in subsequent flotation operations.

[0014] Furthermore, in step S3, the magnetic separation includes a roughing process and a scavenging process. The background field strength for the roughing process is 0.5~1.5T, and the background field strength for the scavenging process is 7~9T, with a magnetic induction gradient of 3~5T / m. By employing a combination of gradient field strengths and a specific magnetic induction gradient, the limonite carrier minerals are initially enriched in the roughing stage, and high-field-strength precise capture is achieved in the scavenging stage, increasing the magnetic separation efficiency by more than 30% while avoiding the entrainment of strongly magnetic gangue minerals.

[0015] Furthermore, in step S3, the molybdenum recovery rate of the limonite phase in the magnetic separation concentrate is ≥40%, and the clay mineral removal rate is ≥90%. By precisely matching the magnetic separation parameters with the mineral characteristics, the efficient recovery of molybdenum carrier minerals is ensured, while the content of viscous substances (clay) in the slurry is reduced from more than 25% in the original ore to less than 2.5%, significantly improving the filtration performance.

[0016] Furthermore, in step S4, the slurry pH is 8.5–9.5. By controlling the pH range, the oxide film on the surface of the molybdenum sulphite is sloughed off, improving the chemisorption efficiency of xanthate collectors while inhibiting the activation of carbonate gangue.

[0017] Furthermore, in step S4, the flotation process consists of one roughing and six scavenging stages; each scavenging stage only adds a collector, and the amount of collector used is reduced by 50% compared to the roughing stage, with the middlings products being returned sequentially.

[0018] Furthermore, in step S4, 0.5~1.5wt% sodium dodecyl sulfonate is added to the flotation pulp to control the rheological properties of the flotation pulp to meet the following condition: shear rate 100s. -1The viscosity is ≤120 mPa·s, and the yield stress is ≤35 Pa. The addition of surfactants improves reagent dispersibility, reducing the emulsion particle size of the composite collector in the pulp to below 5 μm, increasing the reagent adsorption rate on the mineral surface, and simultaneously inhibiting the ineffective consumption of the collector by clay minerals. Rheological parameter control improves flotation bubble mineralization efficiency and increases bubble loading.

[0019] Furthermore, in step S5, a ceramic filter is used for thickening filtration, with a filtration pressure of 0.4~0.6MPa and a filter cake moisture content of ≤12wt%. High-pressure ceramic filtration increases the density of the concentrate filter cake and reduces the moisture content, meeting the direct feeding requirements of subsequent hydrometallurgical processes.

[0020] Furthermore, in step S5, the combined mass ratio of flotation concentrate and magnetic concentrate is 1:(0.8~1.2), and the enrichment ratio of molybdenum concentrate after merging is ≥3.5.

[0021] This invention has the following beneficial technical effects: by constructing a "pre-screening-bar milling" system, it improves the mineral liberation degree while suppressing mud formation, creating favorable conditions for strong magnetic separation. The specific magnetic susceptibility of the molybdenum-based carrier mineral limonite is (0.5×10⁻⁶). -6 ~5×10 -6 m 3 / kg) and the magnetic susceptibility of clay minerals (<10) -7 m 3 Despite significant differences (in kg), an ultra-strong magnetic field separation process (background field strength 8T) was selected to achieve directional enrichment of molybdenum oxide-carrier minerals, resulting in a molybdenum recovery rate of over 40% in the limonite phase and simultaneous removal of over 90% of clay gangue. A novel oxygen-sulfur composite collector system was developed. Through the dual collecting action of sulfide and oxide minerals, a chemical regulation mechanism was constructed at the interface of molybdenum oxide-molybdenum sulfide co-flotation under a flotation slurry system with strong inhibition and strong collection. This overcame the technical challenge of simultaneous recovery of oxygen-sulfur-molybdenum minerals in high-clay systems. With a concentrate enrichment ratio of not less than 3, the overall molybdenum recovery rate in the entire process experiment exceeded 60%. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0024] This uranium-molybdenum deposit is a medium-low temperature hydrothermal porphyry uranium-molybdenum deposit with a high degree of oxidation, abundant slime, and complex ore properties. The molybdenum-bearing minerals are finely intercalated, mainly in colloidal form, and most are amorphous with poor floatability. The raw ore contains 0.262% molybdenum, with an oxidation rate of 54.20%. Molybdenum is partly present as molybdenum oxide in limonite, and partly as molybdenite-calcium ore, uranium-molybdenite, azurite, and sulphite.

[0025] The test samples for each embodiment were all uranium-molybdenum ore that had been crushed, mixed and reduced in size, with a particle size of less than 2 mm. Four portions were taken, each weighing 1 kg, and were numbered A, B, C and D respectively. Example 1

[0026] Four uranium-molybdenum ore samples were pre-screened using a 0.15 mm sieve. The undersize ore entered a high-intensity magnetic separation tank, while the oversize ore entered the grinding process. A rod mill was used to grind the ore to a density of 95% below 0.15 mm. After adjusting the slurry concentration to 20%, the slurry entered the high-intensity magnetic separation process. The magnetic separation media had a toothed plate width of 3 mm, performing one coarse and one scavenging separation. The coarse and scavenging concentrates were combined. The background magnetic field strength for coarsening was 1 T, and for scavenging it was 8 T. The magnetic concentrate was collected. The tailings slurry from the high-intensity magnetic separation was added to a thickening tank, and the thickened slurry was then added to a flotation tank. The slurry temperature was adjusted to 45℃. After stirring for a certain period of time, add flotation reagents, including 2000, 2500, 3000, and 3500 g / t of flotation dispersant (comprising 30% sodium carbonate and 70% sodium silicate), 150 g / t of flotation composite collector (comprising 30% ethyl biflavin, 10% polyoxybutenol dithiophosphate, 20% oxidized paraffin soap, 20% RA935, and 20% sulfonated kerosene), and 40 g / t of pine oil frother. Stir thoroughly for 5 minutes. Open the flotation machine's air inlet valve and scraper to collect the flotation concentrate. The flotation process uses one roughing and six scavenging stages, with only collector added during each scavenging stage, and the amount reduced by 50%. The middlings are returned sequentially. After the flotation process is completed, the flotation concentrate and magnetic concentrate are combined into a molybdenum concentrate.

[0027] After the mineral processing test, solid-liquid separation was performed. After the concentrates were dried, the Mo grade in each concentrate was analyzed, and the Mo recovery rate was calculated. The Mo grades in concentrates A, B, C, and D were 0.385%, 0.452%, 0.553%, and 0.612%, respectively, and the Mo recovery rates were 79.59%, 56.35%, 56.35%, and 47.42%, respectively. Example 2

[0028] Example 2 uses the same process flow as Example 1, the only difference being the type and amount of flotation reagents added. The rougher flotation reagent regime is as follows: 3500 g / t of flotation dispersant (including 20% ​​sodium carbonate and 80% sodium silicate), 100, 150, 200, and 250 g / t of flotation composite collector (including 40% ethyl biflavin, 10% polyoxybutenol dithiophosphate, 20% oxidized paraffin soap, 10% RA935, and 20% sulfonated kerosene), and 30 g / t of MIBC frother. For each scavenging stage, only the collector is added, with the dosage reduced by 50%.

[0029] After the mineral processing test, the Mo grade in each concentrate was analyzed, and the Mo recovery rate was calculated. The Mo grades in concentrates A, B, C, and D were 0.735%, 0.622%, 0.573%, and 0.435%, respectively, and the Mo recovery rates were 29.1%, 48.56%, 60.33%, and 67.52%, respectively. Example 3

[0030] Example 3 uses the same process flow as Example 1, the only difference being the grinding fineness of the ore samples and the flotation reagent regime. The ore samples were pre-screened using 0.2 mm, 0.15 mm, 0.1 mm, and 0.074 mm screens, respectively. The undersize ore entered the strong magnetic separation stirring tank, and the oversize ore entered the grinding process. The samples were ground using a rod mill to a particle size of -0.2 mm, -0.15 mm, -0.1 mm, and -0.074 mm ("-" indicates that the particle size is below this size) to 95% before entering the flotation process. The roughing flotation reagent regime was as follows: 3500 g / t of flotation dispersant (including 35% sodium carbonate and 65% sodium silicate), 150 g / t of flotation composite collector (including 30% ethyl biflavin, 20% polyoxybutenol dithiophosphate ammonium, 30% oxidized paraffin soap, 10% RA935, and 10% sulfonated kerosene), and 40 g / t of 2-octanol frother. Each time the collector is used, only the collector is added, reducing the dosage by 50%.

[0031] After the mineral processing test, the Mo grade in each concentrate was analyzed and the Mo recovery rate was calculated. The Mo grades in concentrates A, B, C, and D were 0.633%, 0.612%, 0.533%, and 0.352%, respectively, and the Mo recovery rates were 38.59%, 47.42%, 53.25%, and 69.66%, respectively.

[0032] Although embodiments of the present invention have been shown and described above, it is understood that these embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and alterations to the above embodiments within the scope of the present invention without departing from its principles and spirit. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A method for enriching molybdenum from low-grade uranium-molybdenum ore, characterized in that, Includes the following steps: The low-grade uranium-molybdenum ore described in S1 has a molybdenum grade of 0.1~0.3wt%, an oxidation rate of ≥50%, and a clay content of ≥25wt%; the uranium-molybdenum ore is crushed to a particle size of less than 2mm; S2 The uranium-molybdenum ore crushed in step S1 is screened using a 0.074~0.2mm grading screen. The undersize ore directly enters the magnetic separation process. The oversize ore is ground using a rod mill. The particle size of the ground ore is more than 95% of the undersize portion of the grading screen. S3 combines the screened ore obtained in step S2 with the ground ore, adds water to prepare a slurry, and performs magnetic separation to obtain magnetic concentrate and magnetic tailings. S4. The magnetic tailings obtained in step S3 are used to prepare a flotation slurry, and a composite flotation reagent is added for flotation to obtain a flotation concentrate. The composite flotation reagent includes 2000~3500 g / t of flotation dispersant, 100~250 g / t of flotation composite collector and 30~40 g / t of flotation frother. The flotation dispersant is a mixed solution of sodium carbonate and sodium silicate. The composition of the flotation composite collector is: 30~40 wt% ethyl biflavonoid, 10~20 wt% polyoxybutenol dithiophosphate ammonium, 20~30 wt% oxidized paraffin soap, 10~20 wt% RA935 and 10~20 wt% sulfonated kerosene. The flotation frother is selected from one or more of pine oil, MIBC and 2-octanol. S5 combines the magnetic concentrate obtained in step S3 with the flotation concentrate obtained in step S4, and then thickens and filters them to obtain the molybdenum concentrate product.

2. The method according to claim 1, characterized in that, In step S2, the rod mill is filled with steel rod media, with a filling rate of 30-40%.

3. The method according to claim 1, characterized in that, In step S3, the magnetic separation includes a roughing and a sweeping. The background field strength of the roughing is 0.5~1.5T, the background field strength of the sweeping is 7~9T, and the magnetic induction gradient is 3~5T / m.

4. The method according to claim 1, characterized in that, In step S3, the molybdenum recovery rate of limonite phase in the magnetic separation concentrate is ≥40%, and the clay mineral removal rate is ≥90%.

5. The method according to claim 1, characterized in that, In step S4, the pH value of the slurry is 8.5~9.

5.

6. The method according to claim 1, characterized in that, In step S4, the flotation process consists of one roughing and six scavenging stages. Only collectors are added during each scavenging stage, and the amount of collector used is reduced by 50% compared to the roughing stage. The middlings products are returned sequentially.

7. The method according to claim 1, characterized in that, In step S4, 0.5-1.5 wt% sodium dodecyl sulfonate is added to the flotation pulp to control the rheological properties of the flotation pulp to meet the following condition: shear rate 100 s⁻¹ -1 The viscosity is ≤120 mPa·s and the yield stress is ≤35 Pa.

8. The method according to claim 1, characterized in that, In step S4, a ceramic filter is used for thickening filtration, with a filtration pressure of 0.4~0.6MPa and a filter cake moisture content of ≤12wt%.

9. The method according to claim 1, characterized in that, In step S5, the combined mass ratio of flotation concentrate and magnetic concentrate is 1:(0.8~1.2), and the enrichment ratio of molybdenum concentrate after merging is ≥3.5.

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