Low-grade molybdenum ore stepped recovery method

Abstract

The invention provides a low-grade molybdenum ore stepped recovery method which comprises the following steps: carrying out primary grading after carrying out coarse crushing and intermediate crushing on raw molybdenum ore to obtain oversize ore, intermediate ore 1, intermediate ore 2 and undersize ore; carrying out photoelectric separation on the intermediate ore 1 to obtain concentrate 1 and tailings 1, carrying out dense medium separation on the intermediate ore 2 to obtain concentrate 2 and tailings 2, and carrying out coarse fraction flotation on the undersize ore to obtain concentrate 3 and tailings 3; the concentrate 1 and the concentrate 2 are subjected to primary slurry making and conveyed into a ball mill to be subjected to primary ore grinding, then secondary classification is conducted through a cyclone, conventional flotation of one-time roughing and one-time scavenging is conducted on overflow slurry of the cyclone, and roughing concentrate and tailings 4 are obtained; and the roughing concentrate and the concentrate 3 are subjected to secondary grinding, pre-concentrate is obtained, the pre-concentrate is subjected to three-time concentration and one-time scavenging, and molybdenum concentrate and molybdenum tailings are obtained. According to the method, the tailing discarding amount in the earlier-stage flotation process is increased, and the recovery rate and the grade of molybdenum are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ore dressing, and particularly relates to a low-grade molybdenum ore step-by-step recovery method. BACKGROUND

[0002] Molybdenum is a refractory metal, which has high strength, high melting point, corrosion resistance, wear resistance and other advantages, and is an indispensable raw material in the manufacturing industry of metallurgy, electricity, chemical industry, aviation and spaceflight.

[0003] With the rapid development of industry, the demand for molybdenum is increasing, and high-quality molybdenum resources are becoming exhausted, and most of the molybdenum ore has become low-grade molybdenum ore. Low-grade molybdenum ore generally refers to mineral resources with low molybdenum grade (such as less than 0.1% Mo) or complex occurrence state and many associated interfering elements. The traditional single flotation process has low recovery efficiency and high cost for such ores, resulting in resource waste.

[0004] The prior art mainly uses methods such as intensified flotation, chemical leaching or biological leaching, but the molybdenum content in low-grade molybdenum ore is low, which easily leads to a small amount of pre-selection tailings in the ore dressing process, resulting in a large amount of low-grade grinding ore in the subsequent process, increasing the subsequent flotation load, and causing the process to be complex, the cycle to be long, and the molybdenum recovery rate to be unstable, thereby increasing the production cost. Therefore, efficient development and utilization of low-grade molybdenum ore to realize efficient, economic and green recovery of molybdenum is of great significance to improve the level of resource comprehensive utilization. SUMMARY

[0005] The present application provides a low-grade molybdenum ore step-by-step recovery method to solve the problems mentioned in the background.

[0006] The present application provides a low-grade molybdenum ore step-by-step recovery method, which comprises the following steps: (1) After coarse crushing and medium crushing of the molybdenum ore, the ore is subjected to one-stage classification by three-layer screening to obtain the oversize ore, the intermediate ore 1, the intermediate ore 2 and the undersize ore; (2) The oversize ore is subjected to fine crushing and returned to the one-stage classification, the intermediate ore 1 is subjected to photoelectric separation to obtain the concentrate 1 and the tailings 1, the intermediate ore 2 is subjected to heavy medium separation to obtain the concentrate 2 and the tailings 2, and the undersize ore is subjected to coarse particle flotation to obtain the concentrate 3 and the tailings 3; (3) The concentrate 1 and the concentrate 2 are subjected to one-stage pulp making and fed into a ball mill for one-stage grinding, the ball mill and a cyclone constitute a closed circuit grinding for two-stage classification, and the overflow slurry of the cyclone is subjected to conventional flotation of one roughing and one scavenging to obtain the roughing concentrate and the tailings 4; (4) The roughing concentrate and the concentrate 3 are subjected to two-stage grinding to obtain the pre-concentrate, the pre-concentrate is subjected to three-stage cleaning and one-stage scavenging to obtain the molybdenum concentrate and the molybdenum scavenging tailings.

[0007] Optionally, the particle size of the discharged ore after coarse crushing is less than or equal to 150 mm, and the particle size of the discharged ore after medium crushing is less than or equal to 50 mm.

[0008] Optionally, the first layer of the three-layer screen has a screen hole of 10 mm, the second layer of the three-layer screen has a screen hole of 3 mm, and the third layer of the three-layer screen has a screen hole of 1 mm.

[0009] Optionally, the size of the ore in the photoelectric sorting process is 3-10 mm, the rejection rate is greater than or equal to 70%, and the grade of the tailings is less than or equal to 0.016%.

[0010] Optionally, the size of the ore in the photoelectric sorting process is 3-10 mm, the rejection rate is greater than or equal to 70%, and the grade of the tailings is less than or equal to 0.016%.

[0011] Optionally, the size of the ore in the photoelectric sorting process is 3-10 mm, the rejection rate is greater than or equal to 70%, and the grade of the tailings is less than or equal to 0.016%.

[0012] Optionally, the size of the ore in the photoelectric sorting process is 3-10 mm, the rejection rate is greater than or equal to 70%, and the grade of the tailings is less than or equal to 0.016%.

[0013] Optionally, the size of the ore in the photoelectric sorting process is 3-10 mm, the rejection rate is greater than or equal to 70%, and the grade of the tailings is less than or equal to 0.016%.

[0014] Optionally, in the first grinding process, the grinding concentration is 70-75%, and the fineness of the discharged ore is 35%-40% of -200 mesh; In the second grinding process, the grinding concentration is 25-30%, and the fineness of the discharged ore is 60%-75% of -325 mesh.

[0015] Optionally, the reagent system of the coarse particle flotation process adopts: the dosage of the collector MO-P4 is 50-80 g / t; the dosage of No. 2 oil is 20-30 g / t; Optionally, the reagent system of the coarse particle flotation process adopts: the dosage of the collector MO-P4 is 50-80 g / t; the dosage of No. 2 oil is 20-30 g / t; In the three-time concentration and one-time scavenging process of the pre-concentrate, an inhibitor is added in the first concentration and the second concentration, and the dosage of the inhibitor in each concentration process is 800-1000 g / t; the inhibitor includes sodium thioglycolate, and the dosage of diesel in the one-time scavenging is 20-40 g / t.

[0016] The low-grade molybdenum ore step-by-step recovery method provided in the application realizes efficient recovery of molybdenum, and has the following beneficial effects compared with the prior art: (1) The application realizes the step-by-step recovery of molybdenum in low-grade molybdenum ore. Through the use of photoelectric separation, heavy medium separation and coarse particle flotation, the particle sizes of the materials that can be treated are different. According to the differences in ore particle size, density and surface properties, molybdenum minerals are enriched in stages, the gangue minerals in the molybdenum ore are pre-eliminated, the energy consumption of subsequent production is reduced, the metal loss is reduced, and the separation efficiency is improved. At the same time, coarse particle flotation and conventional flotation are combined to realize the early elimination technology in the flotation stage, thereby improving the grade of molybdenum flotation feed, improving the recovery rate of molybdenum after flotation, reducing the processing load in the molybdenum flotation process, saving energy consumption in the molybdenum flotation process, reducing production costs, reducing waste liquid discharge in the molybdenum flotation process, and achieving the purpose of reducing costs and increasing efficiency.

[0017] (2) In the conventional flotation and molybdenum concentration stage, MO-P4, No. 2 oil and diesel oil are used together. MO-P4 has strong collecting property for molybdenum and can be applied to the roughing stage to improve the molybdenum recovery rate. Diesel oil has a certain collecting property for molybdenum and can improve the molybdenum concentrate grade.

[0018] (3) In the first and second concentration processes, inhibitors including sodium mercaptoacetate and 4-hydroxy coumarin are added. Sodium mercaptoacetate has two strong polar groups of mercapto and carboxyl in its molecular structure, which forms a stable and dense hydrophilic film on the mineral surface, so that pyrite is inhibited in the slurry. At the same time, 4-hydroxy coumarin has strong chelation (coordination) ability for divalent cations, which chelates with divalent cations (Ca 2+ ) on the surface of gangue minerals to form a stable and hydrophilic surface complex, thereby inhibiting the gangue minerals from floating with the collector MO-P4, indirectly enhancing the hydrophobicity of the molybdenum mineral particle surface, and improving the flotation efficiency and selectivity of the molybdenum mineral through the synergistic effect of sodium mercaptoacetate and 4-hydroxy coumarin, thereby improving the recovery efficiency of molybdenum. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0020] Figure 1 The process diagram of the low-grade molybdenum ore step-by-step recovery method provided by the embodiments of the present application. DETAILED DESCRIPTION

[0021] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are clearly and completely described below. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0022] As shown in Figure 1 The present application provides a low-grade molybdenum ore step-by-step recovery method, comprising the following steps: (1) After coarse crushing and medium crushing of the molybdenum ore, a first classification is performed by three layers of screens, and the obtained mixture of different particle sizes of the raw ore is divided into the above-screen ore, the intermediate ore 1, the intermediate ore 2 and the under-screen ore from the screen up to the screen down according to the particle size from large to small; (2) The above-screen ore is returned to the first classification after fine crushing, the intermediate ore 1 is subjected to photoelectric separation to obtain the concentrate 1 and the tailings 1, the intermediate ore 2 is subjected to heavy medium separation to obtain the concentrate 2 and the tailings 2, and the under-screen ore is subjected to coarse particle flotation to obtain the concentrate 3 and the tailings 3; (3) The concentrate 1 and the concentrate 2 are subjected to primary pulp making, and are fed into a ball mill for primary grinding, and the ball mill and the cyclone constitute a closed circuit grinding for secondary classification, and the overflow slurry of the cyclone is subjected to conventional flotation of one roughing and one scavenging to obtain the roughing concentrate and the tailings 4; (4) The roughing concentrate and the concentrate 3 are subjected to secondary grinding to obtain the pre-concentrate, and the pre-concentrate is subjected to three cleaning and one scavenging to obtain the molybdenum concentrate and the molybdenum scavenging tailings. The tailings 1, the tailings 2, the tailings 3, the tailings 4 and the molybdenum scavenging tailings are mixed together to obtain the final total tailings.

[0023] Optionally, the particle size of the discharged ore after coarse crushing is ≤150 mm, and the particle size of the discharged ore after medium crushing is ≤50 mm.

[0024] Specifically, the molybdenum ore is first crushed to an appropriate particle size by coarse crushing and medium crushing to provide a particle size basis for subsequent separation. Then the above-screen ore (coarse particles) is returned to fine crushing to further reduce the particle size of the mineral, which helps to dissociate molybdenum in the subsequent mineral. The intermediate ore 1 is subjected to photoelectric separation, which takes advantage of the optical property difference between molybdenum minerals and gangue to separate molybdenum minerals and waste rock efficiently, reducing the subsequent grinding and flotation load and energy consumption, and obtaining the concentrate 1 and the tailings 1. The intermediate ore 2 is subjected to heavy medium separation, which separates the minerals by density difference to further enrich the molybdenum minerals with higher density. Then the under-screen ore is directly fed into coarse particle flotation, and the tailings are discarded in the coarse particle flotation process to achieve the purpose of early discarding in the flotation stage, reducing the processing load in the molybdenum flotation process, avoiding over-grinding, and avoiding loss of useful minerals.

[0025] The concentrate 1 and the concentrate 2 are combined and ground to a suitable flotation particle size, a closed-circuit grinding is formed by a ball mill and a cyclone, the overflow slurry of the cyclone is subjected to a conventional flotation of one roughing and one scavenging to obtain a roughing concentrate and a tailing 4, and the particle size is ensured to be uniform. The molybdenum minerals are preliminarily separated by the conventional flotation of one roughing and one scavenging, and the roughing concentrate is subjected to secondary grinding to further dissociate the intergrowth and improve the molybdenum grade. The cyclone classification pressure is 0.045-0.065 MPa.

[0026] Further, the conventional flotation of one roughing and one scavenging refers to a flotation process in which the middlings sequentially returned in one roughing and one scavenging are returned to the previous flotation, and specifically, the roughing molybdenum concentrate and the middlings after the roughing are subjected to one scavenging to obtain the middlings, the middlings are sequentially returned to the previous flotation, and the tailing 4 is combined with the tailings obtained in other processes for centralized treatment.

[0027] The roughing concentrate obtained after the roughing and the concentrate 3 are subjected to secondary grinding to obtain a rough molybdenum concentrate, the rough molybdenum concentrate is subjected to three times of cleaning and one scavenging to obtain a molybdenum concentrate and a molybdenum scavenging tailing. The tailing 1, the tailing 2, the tailing 3, the tailing 4 and the molybdenum scavenging tailing are combined together to form a final total tailing.

[0028] Further, the three times of cleaning and one scavenging refers to a flotation process in which the middlings sequentially returned in three times of cleaning and one scavenging are sequentially returned to the previous cleaning, and specifically, the rough molybdenum concentrate obtained after the secondary grinding is subjected to three times of cleaning, the first cleaning obtains the molybdenum concentrate 1 and the first cleaning middlings, the molybdenum concentrate 1 is subjected to the second cleaning to obtain the molybdenum concentrate 2 and the second cleaning middlings, the molybdenum concentrate 2 is subjected to the third cleaning to obtain the molybdenum concentrate 3 (i.e. the final molybdenum concentrate) and the third cleaning middlings, the third cleaning middlings are sequentially returned to the previous cleaning (i.e. the second cleaning), the first cleaning middlings and the second cleaning middlings are subjected to one molybdenum scavenging, the middlings obtained in the molybdenum scavenging are sequentially returned to the first cleaning, and the tailing is the molybdenum scavenging tailing which is combined with the tailings obtained in other processes for centralized treatment.

[0029] In the ball mill for the primary grinding and the secondary grinding, the grinding medium is ceramic balls which can avoid the influence of iron on the molybdenum grade.

[0030] Further, the tailing 1, the tailing 2, the tailing 3, the tailing 4 and the molybdenum scavenging tailing are combined together to form a final total tailing, and the total tailing is subjected to centralized treatment and used for road paving materials and building bricks, which not only realizes the resource utilization of the tailings, solves the long-term direct piling of the solid waste, avoids the pollution to the surrounding environment, but also reduces the production cost of the building enterprises, has good economic and environmental benefits, and brings economic income to the mining enterprises.

[0031] This application achieves the tiered recovery of molybdenum from low-grade molybdenum ore through the aforementioned method. By utilizing the different particle sizes that can be processed by three different methods—photoelectric separation, heavy media separation, and coarse flotation—molybdenum minerals are enriched in stages according to differences in ore particle size, density, and surface properties. This allows for the pre-disposal of gangue minerals in the raw molybdenum ore, reducing subsequent production energy consumption, minimizing metal loss, and improving separation efficiency. Furthermore, the combination of coarse flotation and conventional flotation enables the early disposal of gangue minerals during the flotation stage, thereby increasing the grade of the molybdenum flotation feed, improving the molybdenum recovery rate after flotation, reducing the processing load during the molybdenum flotation process, saving energy consumption, lowering production costs, and reducing wastewater discharge, thus achieving the goal of cost reduction and efficiency improvement.

[0032] Optionally, for a single grading process, the first layer of the three-layer sieve has a sieve aperture of 10mm, the second layer has a sieve aperture of 3mm, and the third layer has a sieve aperture of 1mm.

[0033] Optionally, during the photoelectric separation process, the feed particle size is 3-10mm (i.e., intermediate ore 1), the waste rate is ≥70%, and the grade of tailings 1 is ≤0.016%.

[0034] Optionally, the feed particle size for heavy media separation is 1-3mm (i.e., intermediate ore 2), the waste rate is ≥55%, and the grade of tailings 2 is ≤0.013%.

[0035] Optionally, the feed concentration during coarse-grained flotation is 35-40%, and the tailings grade is ≤0.011%.

[0036] Optionally, the coarse-grained flotation uses a Beikuang Machinery electrostatic flotation column with a bed static pressure of 3-3.5 kPa, a water flow rate of 10-13 L / min, and a gas flow rate of 0.5-0.8 cm / s.

[0037] Specifically, in the coarse-grained flotation process, reagents are added to the undersize ore. Molybdenum ore is hydrophobic. When the mineral particles adsorbed with the reagent collide with air bubbles in the flotation column, the hydrophobic nonpolar groups cause the molybdenum ore particles to adhere firmly to the air bubbles, thus being lifted by the bubbles and floating to the surface of the pulp to form a foam layer, thereby achieving the separation of molybdenum concentrate from tailings. By applying an electric field within the flotation column, the surface charge of the mineral particles changes, reducing the aggregation of coarse particles or their detachment from air bubbles, while simultaneously promoting the generation of fine bubbles, increasing the collision and adhesion efficiency between coarse particles and air bubbles.

[0038] During the flotation process, static pressure is provided to the bed to ensure sufficient height for the undersize ore, providing ample opportunities for mineralization and washing, preventing excessive deposition and clogging of coarse particles, while maintaining a certain processing capacity of the flotation column. The upward water flow rate is controlled at 10-13 L / min to provide upward hydraulic lifting force, allowing molybdenum mineral particles to float smoothly to the froth layer, while gangue particles sink smoothly and are discharged from the tailings.

[0039] Simultaneously controlling the gas flow rate to 0.5-0.8 cm / s helps generate larger bubbles. Larger bubbles have stronger lifting force, which is key to carrying molybdenum mineral particles to the surface. In this application, by synergistically controlling the bed static pressure, rising water volume, and gas flow rate, and supplementing it with electrostatics, the adhesion between molybdenum mineral particles and large bubbles is enhanced by an electric field, achieving efficient separation in a stable hydraulic environment while minimizing clogging and detachment.

[0040] Optionally, the feed concentration for the rougher in the conventional flotation process is 30-35%, and the tailings grade is ≤0.008%.

[0041] Optionally, during a single grinding process, the grinding concentration is 70-75%, and the discharge fineness is -200 mesh, accounting for 35%-40%. During the secondary grinding process, the grinding concentration is 25-30%, and the discharge fineness is -325 mesh, accounting for 60%-75%.

[0042] Optionally, the coarse-grained flotation reagent system adopts the following dosage: collector MO-P4 dosage 50-80 g / t; No. 2 oil dosage 20-30 g / t; The conventional flotation reagent system uses: collector MO-P4 dosage 50-60 g / t; No. 2 oil dosage 30-40 g / t; During the three-stage beneficiation and one-stage scavenging process of the pre-concentrate, inhibitors are added in the first and second beneficiation processes, with an inhibitor dosage of 800-1000 g / t in each beneficiation process; the inhibitor includes sodium mercaptoacetate, and the diesel dosage in the first scavenging process is 20-40 g / t.

[0043] Specifically, the coarse-grained flotation reagent system employs the following dosages: collector MO-P4 at 50-80 g / t; and No. 2 oil at 20-30 g / t. Collector MO-P4, primarily composed of hydrocarbon oil, forms an oil film on the highly hydrophobic surface of molybdenum mineral particles through physical adsorption and spreading. This significantly enhances the adhesion strength and toughness between bubbles and molybdenum mineral particles, preventing the detachment of large, easily detached coarse particles. No. 2 oil, primarily composed of pine oil, acts as a frother in coarse-grained flotation, increasing the hydrophobicity difference between molybdenum mineral particles and promoting particle adhesion to bubbles. During flotation, in conjunction with the bed static pressure, rising water volume, and gas volume of the electrostatic flotation column, No. 2 oil generates relatively uniform and stable bubbles, providing sufficient lifting force for the molybdenum mineral particles. These bubbles also facilitate the separation of hydrophobic and hydrophilic molybdenum mineral particles, thereby achieving tailings removal in coarse-grained flotation, improving tailings removal efficiency, and ultimately increasing molybdenum recovery.

[0044] Furthermore, during the three-stage beneficiation and one-stage scavenging process of the pre-concentrate, the inhibitors added during the first and second beneficiation processes include 4-hydroxycoumarin, with a dosage of 6-20 g / t.

[0045] Sodium mercaptoacetate contains two strongly polar groups, thiol and carboxyl, in its molecular structure. These groups can strongly chelate or chemically adsorb iron ions on the surface of minerals such as pyrite, forming a stable and dense hydrophilic film on the mineral surface. This film covers the active sites that can adsorb the collector MO-P4, changing the surface from hydrophobic to hydrophilic, thus preventing the adhesion of air bubbles and suppressing them in the slurry.

[0046] Simultaneously, the inhibitor also includes 4-hydroxycoumarin, which, along with sodium thioglycolate, further inhibits other associated sulfide minerals, thereby separating molybdenum ore from other gangues, improving molybdenum ore flotation efficiency, and consequently increasing the grade of molybdenum concentrate, achieving efficient molybdenum recovery. 4-Hydroxycoumarin is an organic heterocyclic compound containing an enediol unit in its structure, which is effective against divalent cations, especially Ca2+. 2+ It has a strong chelating (coordination) ability. Common associated gangue minerals in molybdenum ore, such as calcite (CaCO3) and fluorite (CaF2), will have Ca on their surface in the ore pulp. 2+ When ions partially dissolve or are exposed, 4-hydroxycoumarin molecules, through their enediol structure, interact with the Ca2+ on the surface of these gangue minerals. 2+Chelation occurs, forming stable surface complexes. These complexes are hydrophilic and can be firmly adsorbed onto the surface of calcium-containing gangue, forming a hydrophilic film. This keeps the gangue surface highly hydrophilic, preventing the collector MO-P4 from adsorbing onto the gangue surface covered by the complexes formed by 4-hydroxycoumarin. MO-P4 cannot react with the collector and float, thus being effectively inhibited. This allows the collector MO-P4 to concentrate to the maximum extent on the surface of molybdenum mineral particles, thereby indirectly enhancing the hydrophobicity of the molybdenum mineral particle surface, improving the flotation efficiency and selectivity of molybdenum minerals, and increasing the recovery efficiency of molybdenum.

[0047] The following are embodiments and effect test examples of the present invention, further describing the technical solution and technical effects of the present invention. However, the scope of protection of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not depart from the concept of the present invention are within the scope of protection of the present invention. Furthermore, for those embodiments where specific technical operation steps or conditions are not specified, they are performed according to the techniques or conditions described in general literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially. The ore concentrations mentioned in this application are all mass concentrations. Example 1

[0048] A method for cascade recovery of low-grade molybdenum ore includes the following steps: (1) After coarse crushing (discharge particle size ≤ 150 mm) and medium crushing (discharge particle size ≤ 50 mm) of the raw molybdenum ore with a grade of 0.0433%, it is classified once through a three-layer screen to obtain the oversize ore, intermediate ore 1, intermediate ore 2 and undersize ore. (2) The ore oversize (particle size +10mm) is finely crushed and returned to the first classification. The intermediate ore 1 (particle size 3-10mm) is subjected to photoelectric separation to obtain concentrate 1 and tailings 1. The waste rate is ≥70% and the grade of tailings 1 is ≤0.016%. Intermediate ore 2 (particle size 1-3mm) is subjected to heavy media separation to obtain concentrate 2 and tailings 2, with a waste rate ≥55% and a tailings 2 grade ≤0.013%. The density of the heavy media in the heavy media separation is 1.58g / cm³. 3 ; The undersize ore (particle size -1mm) was fed at a concentration of 38% and subjected to coarse-grained flotation to obtain concentrate 3 and tailings 3, with the grade of tailings 3 being ≤0.011%. The coarse-grained flotation adopted the electrostatic flotation column of Beikuang Machinery, with a bed static pressure of 3 kPa, a water flow rate of 10 L / min, and an air flow rate of 0.5 cm / s. The coarse-grained flotation reagent system was as follows: collector MO-P4 dosage of 50 g / t; No. 2 oil dosage of 20 g / t. Collector MO-P4 was purchased from Changsha Lifu Resources and Environment Technology Co., Ltd. (3) Concentrate 1 and concentrate 2 are slurried once and fed to a ball mill for grinding once. The ball mill and hydrocyclone form a closed-circuit grinding for secondary classification. The overflow slurry of the hydrocyclone is subjected to conventional flotation with one roughing and one scavenging (feed concentration 32%) to obtain roughing concentrate and tailings 4. The feed concentration for a single grinding operation is 70%, and the discharge fineness is -200 mesh, accounting for 35%-40%. The conventional flotation reagent system is as follows: collector MO-P4 dosage 60g / t; No. 2 oil dosage 30g / t. (4) The rough concentrate and concentrate 3 are ground twice to obtain pre-concentrate. The pre-concentrate is then subjected to three fine cleanings and one scavenging to obtain molybdenum concentrate and molybdenum tailings. Tailings 1, 2, 3, 4 and molybdenum tailings are mixed together to form the final total tailings.

[0049] The secondary grinding feed concentration is 25%, and the discharge fineness is -325 mesh, accounting for 60%-75%; In the three-stage selection and one-stage scavenging process, the amount of sodium thioglycolate inhibitor added in the first selection was 800 g / t, and the amount of sodium thioglycolate inhibitor added in the second selection was 800 g / t; the amount of diesel fuel used in the first scavenging was 25 g / t. Example 2

[0050] A method for cascade recovery of low-grade molybdenum ore includes the following steps: (1) After coarse crushing (discharge particle size ≤ 150 mm) and medium crushing (discharge particle size ≤ 50 mm) of the raw molybdenum ore with a grade of 0.0412%, it is classified once through a three-layer screen to obtain the oversize ore, intermediate ore 1, intermediate ore 2 and undersize ore. (2) The ore oversize (particle size +10mm) is finely crushed and returned to the first classification. The intermediate ore 1 (particle size 3-10mm) is subjected to photoelectric separation to obtain concentrate 1 and tailings 1. The waste rate is ≥70% and the grade of tailings 1 is ≤0.016%. Intermediate ore 2 (particle size 1-3mm) is subjected to heavy media separation to obtain concentrate 2 and tailings 2. The waste rate is ≥55%, the grade of tailings 2 is ≤0.013%, and the density of the heavy media in the heavy media separation is 1.55g / cm³. 3 ; The undersize ore (particle size -1mm) was fed at a concentration of 39% and subjected to coarse-grained flotation to obtain concentrate 3 and tailings 3, with the grade of tailings 3 being ≤0.011%. The coarse-grained flotation uses an electrostatic flotation column from Beikuang Machinery, with a bed static pressure of 3.2 kPa, a water flow rate of 12 L / min, and a gas flow rate of 0.55 cm / s. The coarse-grained flotation reagent system is as follows: collector MO-P4 dosage of 55 g / t; No. 2 oil dosage of 24 g / t. (3) Concentrate 1 and concentrate 2 are slurried once and fed to a ball mill for grinding once. The ball mill and hydrocyclone form a closed-circuit grinding for secondary classification. The overflow slurry of the hydrocyclone is subjected to conventional flotation with one roughing and one scavenging (feed concentration 34%) to obtain roughing concentrate and tailings 4. The feed concentration for a single grinding operation is 72%, and the discharge fineness is -200 mesh, accounting for 35%-40%. The conventional flotation reagent system is as follows: collector MO-P4 dosage 55g / t; No. 2 oil dosage 35g / t. (4) The rough concentrate and concentrate 3 are ground twice to obtain pre-concentrate. The pre-concentrate is then subjected to three fine cleanings and one scavenging to obtain molybdenum concentrate and molybdenum tailings. Tailings 1, 2, 3, 4 and molybdenum tailings are mixed together to form the final total tailings.

[0051] The feed concentration for secondary grinding is 25-30%, and the discharge fineness is -325 mesh, accounting for 60%-75%. In the three-stage selection and one-stage scavenging process, the amount of sodium thioglycolate inhibitor added in the first selection was 900 g / t, and the amount of sodium thioglycolate inhibitor added in the second selection was 850 g / t; the amount of diesel fuel used in the first scavenging was 30 g / t. Example 3

[0052] A method for cascade recovery of low-grade molybdenum ore includes the following steps: (1) After coarse crushing (discharge particle size ≤ 150 mm) and medium crushing (discharge particle size ≤ 50 mm) of the raw molybdenum ore with a grade of 0.0426%, it is classified once through a three-layer screen to obtain the oversize ore, intermediate ore 1, intermediate ore 2 and undersize ore. (2) The ore oversize (particle size +10mm) is finely crushed and returned to the first classification. The intermediate ore 1 (particle size 3-10mm) is subjected to photoelectric separation to obtain concentrate 1 and tailings 1. The waste rate is ≥70% and the grade of tailings 1 is ≤0.016%. Intermediate ore 2 (particle size 1-3mm) is subjected to heavy media separation to obtain concentrate 2 and tailings 2, with a waste rate ≥55% and a tailings 2 grade ≤0.013%; The undersize ore (particle size -1mm) is fed at a concentration of 35-40% and subjected to coarse-grained flotation to obtain concentrate 3 and tailings 3, with the grade of tailings 3 being ≤0.011%. The coarse-grained flotation uses a Beikuang Machinery electrostatic flotation column with a bed static pressure of 3.5 kPa, a water flow rate of 13 L / min, and a gas flow rate of 0.8 cm / s. The coarse-grained flotation reagent system is as follows: collector MO-P4 dosage of 80 g / t; No. 2 oil dosage of 30 g / t. (3) Concentrate 1 and concentrate 2 are slurried once and fed to a ball mill for grinding once. The ball mill and hydrocyclone form a closed-circuit grinding for secondary classification. The overflow slurry of the hydrocyclone is subjected to conventional flotation with one roughing and one scavenging (feed concentration 30%) to obtain roughing concentrate and tailings 4. The feed concentration for a single grinding operation is 75%, and the discharge fineness is -200 mesh, accounting for 35%-40%. The conventional flotation reagent system is as follows: collector MO-P4 dosage 60g / t; No. 2 oil dosage 30g / t. (4) The rough concentrate and concentrate 3 are ground twice to obtain pre-concentrate. The pre-concentrate is then subjected to three fine cleanings and one scavenging to obtain molybdenum concentrate and molybdenum tailings. Tailings 1, 2, 3, 4 and molybdenum tailings are mixed together to form the final total tailings.

[0053] The feed concentration for secondary grinding is 25-30%, and the discharge fineness is -325 mesh, accounting for 60%-75%. In the three-stage selection and one-stage scavenging process, the amount of sodium thioglycolate inhibitor added in the first selection was 1000 g / t, and the amount of sodium thioglycolate inhibitor added in the second selection was 950 g / t; the amount of diesel fuel used in the first scavenging was 40 g / t.

[0054] Comparative Example 1 A method for cascade recovery of low-grade molybdenum ore includes the following steps: The difference from Example 2 is that: (1) The grade of the raw molybdenum ore is 0.0431%; (2) Undersize ore (particle size -1mm) is not subjected to coarse-grained flotation; (4) The rougher concentrate obtained by conventional flotation and the undersize ore are subjected to secondary grinding to obtain pre-concentrate. The pre-concentrate is subjected to three cleaning and one scavenging processes to obtain molybdenum concentrate and molybdenum tailings. Tailings 1, tailings 2, tailings 3, tailings 4 and molybdenum tailings are mixed together to form the final total tailings.

[0055] The yield, molybdenum grade, and molybdenum recovery rate of the raw molybdenum ore and the final tailings in Examples 1-3 and Comparative Example 1 are summarized in Table 1, and the results are shown in the table below.

[0056] Table 1

[0057] The step recovery of low-grade molybdenum ore was carried out through the technical solutions of Examples 1 to 3 and Comparative Example 1. As shown in Table 1, the molybdenum recovery scheme provided in this application has a molybdenum concentrate grade of ≥45% and a molybdenum recovery rate of ≥70%. By using three different methods, namely photoelectric separation, heavy medium separation and coarse flotation, the gangue minerals in the raw ore are pre-discarded, reducing the energy consumption of subsequent production and improving the separation efficiency.

[0058] Comparing Examples 1-3 with Comparative Example 1, in Comparative Example 1, the undersize ore was not subjected to coarse-grained flotation. Instead, the rougher concentrate obtained from conventional flotation was directly ground with the undersize ore for a second grinding, followed by three cleaning and one scavenging processes to obtain molybdenum concentrate and molybdenum tailings. Ultimately, the molybdenum grade of the molybdenum concentrate in Comparative Example 1 was 41.58%, and the molybdenum recovery rate was only 52.67%, which is significantly lower than that of Examples 1-3. This indicates that the present application adopts a combination of coarse-grained flotation and conventional flotation, achieving early and timely removal of tailings during the flotation stage. This not only improves the grade of the molybdenum flotation feed and the molybdenum recovery rate after flotation, but also reduces the processing load during the molybdenum flotation process, saves energy consumption, reduces production costs, and reduces wastewater discharge during the molybdenum flotation process, thus achieving the goal of cost reduction and efficiency improvement.

[0059] Example 4 A method for cascade recovery of low-grade molybdenum ore includes the following steps: The difference from Example 2 is that: (1) The grade of the raw molybdenum ore is 0.0462%; (4) The rough concentrate and concentrate 3 are ground twice to obtain pre-concentrate. The pre-concentrate is then subjected to three fine cleanings and one scavenging to obtain molybdenum concentrate and molybdenum tailings.

[0060] In the three-stage selection and one-stage scavenging process, the dosage of sodium thioglycolate inhibitor added in the first selection was 900 g / t, and the dosage of 4-hydroxycoumarin was 20 g / t; the dosage of sodium thioglycolate inhibitor added in the second selection was 850 g / t, and the dosage of 4-hydroxycoumarin was 10 g / t; the dosage of diesel fuel in the first scavenging was 40 g / t.

[0061] Example 5 A method for cascade recovery of low-grade molybdenum ore includes the following steps: The difference from Example 2 is that: (1) The grade of the raw molybdenum ore is 0.0422%; (4) The rough concentrate and concentrate 3 are ground twice to obtain pre-concentrate. The pre-concentrate is then subjected to three fine cleanings and one scavenging to obtain molybdenum concentrate and molybdenum tailings.

[0062] In the three-stage selection and one-stage scavenging process, the dosage of sodium thioglycolate inhibitor added in the first selection was 900 g / t, and the dosage of 4-hydroxycoumarin was 15 g / t; the dosage of sodium thioglycolate inhibitor added in the second selection was 850 g / t, and the dosage of 4-hydroxycoumarin was 15 g / t; the dosage of diesel fuel in the first scavenging was 40 g / t.

[0063] Example 6 A method for cascade recovery of low-grade molybdenum ore includes the following steps: The difference from Example 2 is that: (1) The grade of the raw molybdenum ore is 0.0455%; (4) The rough concentrate and concentrate 3 are ground twice to obtain pre-concentrate. The pre-concentrate is then subjected to three fine cleanings and one scavenging to obtain molybdenum concentrate and molybdenum tailings.

[0064] In the three-stage selection and one-stage scavenging process, the dosage of sodium thioglycolate inhibitor added in the first selection was 900 g / t, and the dosage of 4-hydroxycoumarin was 6 g / t; the dosage of sodium thioglycolate inhibitor added in the second selection was 850 g / t, and the dosage of 4-hydroxycoumarin was 10 g / t; the dosage of diesel fuel in the first scavenging was 40 g / t.

[0065] Comparative Example 2 A method for cascade recovery of low-grade molybdenum ore includes the following steps: The difference from Example 5 is that: (1) The grade of the raw molybdenum ore is 0.0462%; (4) In the process of three selections and one sweep, the amount of sodium thioacetate inhibitor added in the first selection is 800g / t, and the amount of 4-hydroxycoumarin is 5g / t; the amount of sodium thioacetate inhibitor added in the second selection is 800g / t, and the amount of 4-hydroxycoumarin is 15g / t; the amount of diesel fuel used in the first sweep is 40g / t.

[0066] Comparative Example 3 A method for cascade recovery of low-grade molybdenum ore includes the following steps: The difference from Example 5 is that: (1) The grade of the raw molybdenum ore is 0.0517%; (4) The rough concentrate and concentrate 3 are ground twice to obtain pre-concentrate. The pre-concentrate is then subjected to three fine cleanings and one scavenging to obtain molybdenum concentrate and molybdenum tailings.

[0067] In the three-stage selection and one-stage scavenging process, the dosage of sodium thioglycolate inhibitor added in the first selection was 800 g / t, and the dosage of 4-hydroxycoumarin was 15 g / t; the dosage of sodium thioglycolate inhibitor added in the second selection was 800 g / t, and the dosage of 4-hydroxycoumarin was 5 g / t; the dosage of diesel fuel in the first scavenging was 40 g / t.

[0068] Comparative Example 4 A method for cascade recovery of low-grade molybdenum ore includes the following steps: The difference from Example 5 is that: (1) The grade of the raw molybdenum ore is 0.0416%; (4) The rough concentrate and concentrate 3 are ground twice to obtain pre-concentrate. The pre-concentrate is then subjected to three fine cleanings and one scavenging to obtain molybdenum concentrate and molybdenum tailings.

[0069] In the three-stage selection and one-stage scavenging process, the dosage of sodium thioglycolate inhibitor added in the first selection was 800 g / t, and the dosage of 4-hydroxycoumarin was 20.5 g / t; the dosage of sodium thioglycolate inhibitor added in the second selection was 800 g / t, and the dosage of 4-hydroxycoumarin was 15 g / t; the dosage of diesel fuel in the first scavenging was 40 g / t.

[0070] Comparative Example 5 A method for cascade recovery of low-grade molybdenum ore includes the following steps: The difference from Example 5 is that: (1) The grade of the raw molybdenum ore is 0.0537%; (4) The rough concentrate and concentrate 3 are ground twice to obtain pre-concentrate. The pre-concentrate is then subjected to three fine cleanings and one scavenging to obtain molybdenum concentrate and molybdenum tailings.

[0071] In the three-stage selection and one-stage scavenging process, the dosage of sodium thioglycolate inhibitor added in the first selection was 800 g / t, and the dosage of 4-hydroxycoumarin was 15 g / t; the dosage of sodium thioglycolate inhibitor added in the second selection was 800 g / t, and the dosage of 4-hydroxycoumarin was 20.5 g / t; the dosage of diesel fuel in the first scavenging was 40 g / t.

[0072] The yield, molybdenum grade, and molybdenum recovery rate of the raw molybdenum ore and the final tailings from Examples 4-6 and Comparative Examples 2-5 are summarized in Table 2, and the results are shown in the table below.

[0073] Table 2

[0074] As shown in Table 2, the molybdenum grade and recovery rate of Examples 4-6 were significantly improved compared to Examples 1-3. In Examples 4-6, in addition to sodium thioglycolate, 4-hydroxycoumarin was added as an inhibitor. 4-hydroxycoumarin can react with Ca on the surface of gangue minerals. 2+ Chelation occurs, forming a stable surface complex that is firmly adsorbed onto the surface of calcium-containing gangue, forming a hydrophilic film. The calcium-containing gangue cannot react with the collector MO-P4 and thus floats, indirectly enhancing the hydrophobicity of the molybdenum mineral particles, improving the flotation efficiency and selectivity of molybdenum minerals, and increasing molybdenum recovery efficiency. Meanwhile, the molybdenum grade and recovery rate of Comparative Examples 2-5 were lower than those of Examples 4-6, but higher than those of Examples 1-3, indicating that the addition amount of 4-hydroxycoumarin needs to be controlled within a suitable range of 6-20 g / t. Excessive addition did not further improve the molybdenum grade and recovery rate, but instead increased reagent waste.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for the stepwise recovery of low-grade molybdenum ores, characterized in that, The method comprises the following steps: (1) Coarse crushing and medium crushing are performed on the molybdenum ore, and then one-stage classification is performed on the three-layer screen to obtain the screen-up ore, the intermediate ore 1, the intermediate ore 2 and the screen-down ore; (2) The screen-up ore is finely crushed and returned to the one-stage classification, the intermediate ore 1 is optoelectronic sorted to obtain the concentrate 1 and the tailings 1, the intermediate ore 2 is heavy medium sorted to obtain the concentrate 2 and the tailings 2, and the screen-down ore is subjected to coarse-grained flotation to obtain the concentrate 3 and the tailings 3; (3) The concentrate 1 and the concentrate 2 are subjected to one-stage slurry making and then are fed into a ball mill for one-stage grinding, the ball mill and the cyclone constitute a closed circuit grinding for two-stage classification, the overflow slurry of the cyclone is subjected to conventional flotation of one roughing and one scavenging to obtain the roughing concentrate and the tailings 4; (4) The roughing concentrate and the concentrate 3 are subjected to two-stage grinding to obtain the pre-concentrate, and the pre-concentrate is subjected to three-stage cleaning and one-stage scavenging to obtain the molybdenum concentrate and the molybdenum scavenging tailings.

2. The low-grade molybdenum ore stepwise recovery method according to claim 1, characterized by, The particle size of the ore discharged after the coarse crushing is less than or equal to 150 mm, and the particle size of the ore discharged after the medium crushing is less than or equal to 50 mm.

3. The low-grade molybdenum ore stepwise recovery method according to claim 1, characterized by, The first layer of the three-layer screen has a screen hole of 10 mm, the second layer has a screen hole of 3 mm, and the third layer has a screen hole of 1 mm.

4. The low-grade molybdenum ore stepwise recovery method according to claim 1, characterized by, In the optoelectronic sorting process, the feed size is 3-10 mm, the rejection rate is greater than or equal to 70%, and the grade of the tailings 1 is less than or equal to 0.016%.

5. The low-grade molybdenum ore stepwise recovery method according to claim 1, characterized by, The heavy medium separation gives a feed grain size of 1-3 mm, a heavy medium density of 1.55-1.58 g / cm 3 , a discard rate of ≥ 55%, and a tailing 2 grade of ≤ 0.013%.

6. The low-grade molybdenum ore stepwise recovery method according to claim 1, characterized by, In the coarse-grained flotation process, the feed concentration is 35-40%, and the grade of the tailings 3 is less than or equal to 0.011%.

7. The low-grade molybdenum ore stepwise recovery method according to claim 1, characterized by, In the coarse-grained flotation process, a fluidized flotation column is used, the bed static pressure is 3-3.5 KPa, the rising water flow is 10-13 L / min, and the gas flow is 0.5-0.8 cm / s.

8. The low-grade molybdenum ore stepwise recovery method according to claim 1, characterized by, In the conventional flotation process, the feed concentration of the one roughing is 30-35%, and the grade of the tailings 4 is less than or equal to 0.008%.

9. The low-grade molybdenum ore stepwise recovery method according to claim 1, characterized by, In the one-stage grinding process, the grinding concentration is 70-75%, and the fineness of the discharged ore is 35%-40% of -200 mesh; In the two-stage grinding process, the grinding concentration is 25-30%, and the fineness of the discharged ore is 60%-75% of -325 mesh.

10. The method according to any one of claims 1 to 9, wherein the low-grade molybdenum ore is a molybdenum ore containing 0.01 to 0.1% of molybdenum. In the coarse-grained flotation process, the collector MO-P4 is used in an amount of 50-80 g / t, and the No. 2 oil is used in an amount of 20-30 g / t; In the conventional flotation process, the collector MO-P4 is used in an amount of 50-60 g / t, and the No. 2 oil is used in an amount of 30-40 g / t; In the three-stage cleaning and one-stage scavenging process of the pre-concentrate, an inhibitor is added in the first cleaning and the second cleaning, and the amount of the inhibitor used in each cleaning process is 800-1000 g / t; the inhibitor comprises sodium thioglycolate, and the amount of diesel used in the one-stage scavenging is 20-40 g / t.

Images