Method for enriching molybdenum from low-grade uranium-molybdenum ore

Abstract

The invention discloses a method for enriching molybdenum from low-grade uranium-molybdenum ore, and belongs to the technical field of ore dressing. In order to solve the problems that low-grade uranium-molybdenum ore is high in oxidation degree, micro-fine particles are disseminated, and the traditional dressing and smelting efficiency is low, the invention provides a stage grinding-super magnetic separation-oxygen-sulfur bulk flotation synergistic process. The particle size is controlled through pre-screening and rod milling, the phenomenon that minerals are over-ground and argillization is reduced, and the appropriate flotation and magnetic separation size fraction maximization are achieved; directional enrichment of a limonite carrier is realized by combining magnetic separation of an ultra-strong magnetic field, and clay gangue is removed; and the synchronous recovery of molybdenum oxide and molybdenum sulfide is realized by adopting a composite collecting agent and a grading flotation strategy. The method has the outstanding advantages of being simple in process, high in product recovery rate, convenient to operate, low in production cost and the like, and efficient beneficiation and enrichment of the low-grade uranium-molybdenum ore are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of radioactive associated mineral beneficiation, and in particular relates to a beneficiation method for enriching molybdenum from low-grade uranium-molybdenum ore. Background Art

[0002] Co-existing uranium ores account for a certain proportion of uranium resources. Uranium and molybdenum have similar chemical properties, so they often exist in the form of associated elements in nature. In recent years, with the continuous development and utilization of uranium-molybdenum ore resources in my country, high-grade uranium-molybdenum ore resources that are easy to select and have low production costs have been exhausted, and low-grade uranium-molybdenum ore resources have gradually become a potential research object. At present, the development and utilization of uranium-molybdenum ores in my country are mainly based on direct hydrometallurgy of raw ore, including concentrated acid leaching, pressurized oxygen leaching, conventional stirred acid leaching, conventional stirred alkaline leaching, etc. The choice of development and utilization method mainly depends on the grade, particle size composition, oxidation degree and other ore properties of uranium-molybdenum ore.

[0003] A type of low-grade uranium-molybdenum ore is a medium-low temperature hydrothermal porphyry uranium-molybdenum deposit with complex ore properties, high clay mineral content, high oxidation degree, and fine-grained molybdenum-containing minerals without crystal form. The main molybdenum-containing minerals in the ore are limonite, molybdenum calcium ore, and uranium-molybdenum ore. The gangue minerals are mainly quartz, clay minerals and feldspar. Molybdenum is partially present in limonite in the form of molybdenum oxide, and partially in the form of molybdenum calcium ore, uranium-molybdenum ore, blue molybdenum ore and colloidal sulfide molybdenum ore.

[0004] The hydrometallurgical process currently used cannot achieve efficient and economic recovery of this type of low-grade uranium-molybdenum ore. The main reasons are: 1) The original ore grade is low, the direct hydrometallurgical cost is high, and the economic benefits are low; 2) The typical low-grade uranium-molybdenum ore has a high content of fine minerals, and solid-liquid separation is difficult; 3) The pressurized oxygen leaching of the original ore has a small processing capacity, requiring a large oxygen pressure reactor and related supporting equipment, and the equipment investment is large; 4) The leaching rate of conventional stirring leaching is low, and the resource utilization rate is low. Therefore, it is necessary to enrich the ore through beneficiation and discard a large amount of gangue minerals to achieve efficient enrichment and recovery.

[0005] CN117443567A discloses a method for physical beneficiation and enrichment of high-clay low-grade uranium-molybdenum ore, wherein a dispersant is added during the grinding process to strengthen the separation of mineral particles, the grinding product is screened into multiple particle sizes, and targeted sorting is performed based on the difference in mineral properties of each particle size. CN117737477A discloses a method for extracting uranium and molybdenum from an encapsulated uranium-molybdenum ore, wherein the encapsulated uranium-molybdenum ore is subjected to magnetic separation treatment at a magnetic field strength of more than 2T to obtain a magnetic concentrate and a magnetic tailing; the magnetic concentrate is subjected to a first stage of oxidation acid leaching to obtain a first stage of leaching solution; the first stage of leaching solution and the magnetic tailing are mixed for a second stage of oxidation acid leaching to obtain a uranium-molybdenum leaching solution. CN119287180A discloses a method for treating an easily sludged and encapsulated uranium-containing primary colloidal sulfide molybdenum ore, comprising the steps of: coarsely crushing and finely crushing the easily sludged and encapsulated uranium-containing primary colloidal sulfide molybdenum ore, and then performing a first stage classification to obtain a first stage fine mud and a first stage material; coarsely grinding the first stage material and then performing a second stage classification to obtain a second stage fine mud and a second stage material; and finely grinding the second stage material to obtain a finely ground material; placing the first stage fine mud, the second stage fine mud and the finely ground material obtained in step (1) in an alkali solution, and pressurizing them with an oxygen-containing atmosphere to perform a positive pressure alkali leaching treatment, wherein the alkali solution is an aqueous solution of an alkali metal hydroxide, and the pH value of the positive pressure alkali leaching stage is controlled to be above 10, and then performing solid-liquid separation to obtain a molybdenum-rich leaching solution and a uranium-rich leaching residue; and acid leaching the uranium-rich leaching residue obtained in step (2) to obtain a uranium-rich leaching solution.

[0006] Although these existing technologies have proposed their own technical solutions for some uranium-molybdenum ores, these technical solutions are difficult to apply to such low-grade uranium-molybdenum ores. The main target minerals for the beneficiation of such low-grade uranium-molybdenum ores are colloid-sulfide molybdenum ore and oxide molybdenum ore. Due to the particularity of surface properties and occurrence states, the traditional single beneficiation process is not adaptable enough. The main technical difficulties in beneficiation are: 1) The surface properties of the mineral are not conducive to flotation. Colloidal molybdenite: The surface is colloidal or amorphous, and its hydrophobicity is significantly weaker than that of molybdenite, making it difficult to be effectively adsorbed by conventional non-polar hydrocarbon collectors. The surface is easily oxidized or adsorbed with ore slime to form a hydrophilic layer, which hinders the contact between the collector and the mineral surface. Oxidized molybdenum ore (such as calcium molybdenite CaMoO4, etc.): The surface is highly hydrophilic, with extremely poor natural floatability, and cannot be directly combined with conventional collectors through physical adsorption. It is necessary to restore the hydrophobicity through chemical activation (such as sulfidation treatment), or use traditional hydrocarbon acid collectors, but the selectivity is poor, the grade of the selected concentrate is very low, and the metallurgical cost is still high.

[0007] 2) The mineral occurrence state is complex and fine particles are embedded, which is not conducive to effective dissociation. From process mineralogy, it is known that colloid molybdenum sulfide ore is closely associated with clay minerals, iron oxides or uranium minerals, while molybdenum oxide ore is mostly embedded with carbonate or silicate gangue, and conventional grinding is difficult to achieve monomer dissociation. Both are often dispersed in the ore in micron or nanometer particles, and are easily wrapped by gangue minerals or form "slime cover", reducing the sorting efficiency.

[0008] In order to develop and utilize the above-mentioned low-grade uranium-molybdenum ores, it is urgent to develop a systematic method to achieve dual capture of sulfide and oxidized minerals through mineral surface modification, customized reagent systems and multi-process coordination, thereby improving the grade of ore entering the metallurgical process, reducing production costs, and realizing efficient and economical utilization of such low-grade uranium-molybdenum ores. Summary of the invention

[0009] The purpose of the present invention is to provide a method for enriching molybdenum from low-grade uranium-molybdenum ore, and to develop a targeted flotation composite collector to address the difficulties of coexistence of colloid-sulfurized molybdenum ore and oxidized molybdenum ore, complex mineral occurrence state and difficulty in effective dissociation, and to provide a set of mineral processing and enrichment processes based on the flotation composite collector to improve the grade and recovery rate of low-grade uranium-molybdenum ore. The purpose of the present invention is achieved through the following technical solutions.

[0010] A method for enriching molybdenum from low-grade uranium-molybdenum ore comprises the following steps: S1 crushing 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 0.074-0.2 mm grading screen, and the ore under the screen directly enters the magnetic separation process; the ore on the screen is ground by a rod mill, and the particle size of the ore after grinding accounts for more than 95% of the part under the grading screen; S3: combining the undersize ore obtained in step S2 with the ground ore, adding water to prepare slurry, and performing magnetic separation to obtain magnetic concentrate and magnetic tailings; S4: preparing flotation slurry with the magnetic tailings obtained in step S3, adding a composite flotation agent for flotation to obtain a flotation concentrate; the composite flotation agent comprises 2000-3500 g / t of a flotation dispersant, 100-250 g / t of a flotation composite collector and 30-40 g / t of a flotation frother; the flotation dispersant is a mixed solution of sodium carbonate and sodium silicate; the flotation composite collector comprises: 30-40 wt% ethyl dixanthate, 10-20 wt% polyoxybutylene alcohol ammonium dithiophosphate, 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 carbinol) and octanol; S5 combines the magnetic concentrate obtained in step S3 and the flotation concentrate obtained in step S4, and obtains a molybdenum concentrate product after dense filtration.

[0011] The present invention provides a method for enriching molybdenum from low-grade uranium-molybdenum ore. By developing a targeted flotation composite collector and through the dual capture of sulfide and oxide minerals, a chemical regulation mechanism for the co-flotation interface of molybdenum oxide-molybdenum sulfide minerals is constructed under a flotation slurry system with strong inhibition and strong capture, thereby overcoming the technical difficulty of synchronous recovery of oxygen-sulfur-molybdenum minerals in a high-clay system.

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

[0013] Furthermore, in step S2, the rod mill is filled with steel rods with a filling rate of 30-40%. By limiting the steel rod filling rate, the over-grinding phenomenon of the ore is effectively controlled, the proportion of the intermediate particle size suitable for magnetic separation / flotation is increased by more than 15%, and the generation of ultra-fine particles below 0.074 mm is reduced, which significantly improves the rheological properties of the slurry in subsequent flotation operations.

[0014] Furthermore, the magnetic separation in step S3 includes a roughing separation and a scavenging separation, the background field strength of the roughing separation is 0.5-1.5 T, the background field strength of the scavenging separation is 7-9 T, and the magnetic induction gradient is 3-5 T / m. The gradient field strength combination and the specific magnetic induction gradient are used to make the limonite carrier minerals initially enriched in the roughing stage, and the high field strength is accurately captured in the scavenging stage, and the magnetic separation efficiency is increased by more than 30%, while avoiding the entrainment of strong magnetic gangue minerals.

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

[0016] Furthermore, in step S4, the pH value of the slurry is 8.5-9.5. By controlling the pH value range, the oxide film on the surface of the colloidal sulfide molybdenum ore is peeled off, the chemical adsorption efficiency of the xanthate collector is improved, and the activation of carbonate gangue is inhibited.

[0017] Furthermore, in step S4, flotation adopts one roughing and six scavenging; only collector is added in each scavenging, and the amount of collector is reduced by 50% compared with the roughing, and the intermediate ore products are returned in sequence.

[0018] Further, in step S4, 0.5-1.5 wt% sodium dodecyl sulfate is added to the flotation pulp to control the rheological properties of the flotation pulp to meet the following conditions: shear rate 100 s -1The viscosity is ≤120mPa·s and the yield stress is ≤35Pa. By adding surfactants to improve the dispersibility of the reagent, the emulsified particle size of the composite collector in the slurry is reduced to below 5μm, the adsorption rate of the reagent on the mineral surface is increased, and the ineffective consumption of the collector by clay minerals is suppressed. By controlling the rheological parameters, the flotation bubble mineralization efficiency is improved and the bubble loading capacity is increased.

[0019] Furthermore, in step S5, a ceramic filter is used for dense filtration, the filtration pressure is 0.4-0.6 MPa, and the moisture content of the filter cake is ≤12wt%. The density of the concentrate filter cake is increased and the moisture content is reduced by high-pressure ceramic filtration, which meets the direct feeding requirements of the subsequent hydrometallurgical process.

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

[0021] The present invention has the following beneficial technical effects: by constructing a "pre-screening-rod mill" system, the degree of mineral dissociation is improved while suppressing the mud phenomenon, creating favorable conditions for strong magnetic separation. The specific magnetic susceptibility of the carrier mineral limonite based on molybdenum (0.5×10 -6 ~5×10 -6 m 3 / kg) and the magnetic susceptibility of clay minerals (<10 -7 m 3 / kg), the ultra-strong magnetic field magnetic separation process (background field strength 8T) was selected to achieve directional enrichment of colloidal sulfide molybdenum ore-molybdenum oxide carrier minerals, so that the molybdenum recovery rate of the limonite phase reached more than 40%, and more than 90% of the clay gangue was removed simultaneously. A new oxygen-sulfur composite collector system was developed. Through the dual capture of sulfide and oxidized minerals, a chemical regulation mechanism for the co-flotation interface of molybdenum oxide-molybdenum sulfide minerals was constructed under a flotation slurry system with strong inhibition and strong capture, and the technical difficulties of simultaneous recovery of oxygen-sulfur-molybdenum minerals in high-clay systems were overcome. When the concentrate enrichment ratio was not less than 3, the comprehensive recovery rate of molybdenum in the whole process test reached more than 60%. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings of the specification. Obviously, the described implementation is only a part of the implementation of the present invention, not all of the implementations. Based on the implementation of the present invention, all other implementations obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] A certain uranium-molybdenum mine is a medium-low temperature hydrothermal porphyry uranium-molybdenum deposit with a high degree of oxidation, a large amount of ore mud, and complex ore properties. The molybdenum-containing minerals are finely embedded and mainly colloidal minerals. Most of the molybdenum minerals are amorphous and have poor floatability. The original ore contains 0.262% molybdenum, and the oxidation rate reaches 54.20%. The molybdenum is partially present in the form of molybdenum oxide in limonite, and partially in the form of molybdenum calcium ore, uranium-molybdenum ore, blue molybdenum ore and colloidal sulfur-molybdenum ore.

[0025] The test samples of each embodiment are all uranium-molybdenum ore that has been crushed, mixed and shrunk, with a particle size of less than 2 mm. Four portions, each weighing 1 kg, are taken and 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 ore under the sieve entered the strong magnetic separation mixing barrel, and the ore on the sieve entered the grinding process. The rod mill was used to grind the ore to 95% below 0.15 mm. After the pulp concentration was adjusted to 20%, the pulp entered the strong magnetic separation process. The strong magnetic separation medium tooth plate width was 3 mm, one roughing and one sweeping, the roughing and sweeping concentrates were merged, the roughing background magnetic field intensity was 1 T, the sweeping background magnetic field intensity was 8 T, and the magnetic separation concentrate was collected. The tailings pulp after strong magnetic separation was added to the thickening tank, and the thickened pulp was added to the flotation mixing barrel, and the pulp temperature was adjusted to 45 ° C. After stirring for a certain period of time, add flotation reagents, such as 2000, 2500, 3000, and 3500 g / t of flotation dispersant (including 30% sodium carbonate and 70% sodium silicate), 150 g / t of flotation composite collector (including 30% ethyl dixanthate, 10% polyoxybutylene alcohol ammonium dithiophosphate, 20% oxidized paraffin soap, 20% RA935, and 20% sulfonated kerosene), and 40 g / t of pine oil foaming agent, and stir thoroughly for 5 minutes. Open the air inlet valve and scraper of the flotation machine to collect the flotation concentrate. The flotation process adopts 1 roughing and 6 scavenging. Only collector is added for each scavenging, and the dosage is reduced by 50%. The intermediate ore products are returned in sequence. After the flotation process is completed, the flotation concentrate and magnetic separation concentrate are combined into molybdenum concentrate.

[0027] After the beneficiation test, solid-liquid separation was carried out, and after the concentrate was dried, the Mo grade in each concentrate was analyzed and the Mo recovery rate was calculated. The Mo grades in the concentrates of 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 adopts the same process flow as Example 1, the only difference is the type and amount of flotation reagents added, the roughing flotation reagent system: 3500 g / t of flotation dispersant (including 20% ​​sodium carbonate, 80% sodium silicate), 100, 150, 200, 250 g / t of flotation composite collector (including 40% ethyl dixanthate, 10% polyoxybutylene alcohol ammonium dithiophosphate, 20% oxidized paraffin soap, 10% RA935, 20% sulfonated kerosene), 30 g / t of MIBC frother. Only the collector is added each time, and the amount is reduced by 50%.

[0029] After the ore dressing test, the Mo grade in each concentrate was analyzed and the Mo recovery rate was calculated. The Mo grades in the concentrates of 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 adopts the same process flow as Example 1, the only difference is the grinding fineness of the ore sample and the flotation reagent system. The ore samples are pre-screened using 0.2 mm, 0.15 mm, 0.1 mm, and 0.074 mm screens, respectively. The ore under the screen enters the strong magnetic separation stirring barrel, and the ore on the screen enters the grinding process. The rod mill is used to grind to -0.2 mm, -0.15 mm, -0.1 mm, and -0.074 mm ("-" represents the particle size below) and accounts for 95% before entering the flotation process. The roughing flotation reagent system is: 3500g / t of flotation dispersant (including 35% sodium carbonate and 65% sodium silicate), 150g / t of flotation composite collector (including 30% ethyl dixanthate, 20% polyoxybutylene alcohol ammonium dithiophosphate, 30% oxidized paraffin soap, 10% RA935, 10% sulfonated kerosene), and 40g / t of octanol foaming agent. Only collector is added each time the sweep is performed, and the dosage is reduced by 50%.

[0031] After the ore dressing test, the Mo grade in each concentrate was analyzed and the Mo recovery rate was calculated. The Mo grades in the concentrates of 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 the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. The protection scope of the present invention is defined by the claims and their equivalent technical solutions.

Claims

1. A method for enriching molybdenum from low-grade uranium-molybdenum ore, characterized in that: The following steps are involved: S1 crushing 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 0.074-0.2 mm grading screen, and the ore under the screen directly enters the magnetic separation process; the ore on the screen is ground by a rod mill, and the particle size of the ore after grinding accounts for more than 95% of the part under the grading screen; S3: combining the undersize ore obtained in step S2 with the ground ore, adding water to prepare slurry, and performing magnetic separation to obtain magnetic concentrate and magnetic tailings; S4: preparing flotation slurry with the magnetic tailings obtained in step S3, adding a composite flotation agent for flotation to obtain a flotation concentrate; the composite flotation agent comprises 2000-3500 g / t of a flotation dispersant, 100-250 g / t of a flotation composite collector and 30-40 g / t of a flotation frother; the flotation dispersant is a mixed solution of sodium carbonate and sodium silicate; the flotation composite collector comprises: 30-40 wt% ethyl dixanthate, 10-20 wt% polyoxybutylene alcohol ammonium dithiophosphate, 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 octanol; S5 combines the magnetic concentrate obtained in step S3 and the flotation concentrate obtained in step S4, and obtains a molybdenum concentrate product after dense filtration.

2. The method according to claim 1, characterized in that 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%.

3. The method according to claim 1, characterized in that In step S2, the rod mill is filled with steel rod medium, and the filling rate is 30-40%.

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

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

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

5.

7. The method according to claim 1, characterized in that In step S4, flotation is performed using one roughing and six scavenging processes; only collector is added in each scavenging process, and the amount of collector is reduced by 50% compared with the roughing process, and the intermediate ore products are returned in sequence.

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

9. The method according to claim 1, characterized in that: In step S4, a ceramic filter is used for dense filtration, the filtration pressure is 0.4-0.6 MPa, and the moisture content of the filter cake is ≤12wt%.

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

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