A mineral processing method for recovering ultra-low-grade scheelite from molybdenum tailings.

Abstract

This invention belongs to the field of mineral resource recycling technology, specifically disclosing a beneficiation method for recovering ultra-low-grade scheelite from molybdenum tailings. For refractory scheelite with severe alteration and mudding, the method employs pre-slurry conditioning, enhanced pretreatment with reagents moved forward, followed by grinding and classification of the raw ore. By combining collectors, the refractory scheelite is synergistically recovered, ultimately obtaining a tungsten concentrate with a grade >26%, achieving a comprehensive actual recovery rate of 77%. This invention's process achieves full recovery and utilization of refractory scheelite resources in tailings, while reducing the operating costs of refractory ore recovery, creating considerable economic and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of mineral resource recycling technology, and specifically discloses a mineral processing method for recovering ultra-low grade scheelite from molybdenum tailings. Background Technology

[0002] Tungsten, as an important strategic metal, is widely used in key fields such as cemented carbide, special steel, aerospace, and defense due to its high density, high hardness, and excellent high-temperature performance. For a long time, the global tungsten industry has mainly relied on high-grade wolframite and easily beneficiated scheelite resources with simple intergrowth relationships. However, after years of large-scale mining, these high-quality resources are becoming increasingly depleted.

[0003] Currently, some progress has been made in the technology for recovering scheelite from molybdenum ore. However, the ore sources are gradually shifting towards complex and difficult-to-process resources. Among them, the proportion of scheelite with severe alteration and mud formation is continuously increasing, making it increasingly difficult to recover scheelite from tailings resources. The surface of scheelite is contaminated by alteration or closely associated with calcium-bearing gangue minerals (such as calcite and fluorite), which leads to the complexity of its surface physicochemical properties and significantly reduces the selective collection and inhibition effects of traditional flotation reagents. In addition, a large amount of fine mud is easily generated during the mining and grinding process. This fine mud not only covers the surface of scheelite, hindering its interaction with collectors, but also increases the viscosity of the slurry, deteriorates the flotation environment, and leads to a sharp decline in concentrate grade and recovery rate.

[0004] Traditional scheelite flotation processes employ ambient temperature roughing followed by heated cleaning. However, single collectors are ineffective at selectively collecting refractory scheelite, leading to a decline in both concentrate grade and recovery rate, and increased reagent consumption. Existing reagent regimes are less effective at inhibiting the formation of calcareous gangue ores with similar floatability to the target mineral in scheelite, further highlighting the difficulty in separating scheelite from calcareous gangue minerals. Therefore, developing new processes capable of efficiently processing such heavily altered and muddy refractory scheelite has become a critical technical challenge urgently needing to be addressed in the current tungsten resource beneficiation field. Summary of the Invention

[0005] To address the problems in the background art, this invention discloses a beneficiation method for recovering ultra-low-grade scheelite from molybdenum tailings, which achieves full recovery and utilization of difficult-to-benefit scheelite resources in tailings and reduces the operating cost of difficult-to-benefit ore recovery.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A beneficiation method for recovering ultra-low-grade scheelite from molybdenum tailings specifically includes the following steps:

[0008] S1. Slurry Pretreatment: Sodium carbonate, a scheelite modifier, is added to the feed pipe of the flotation column in the final scavenging stage of upstream sulfur beneficiation. An inhibitor is added to the tailings box of the upstream sulfur beneficiation operation. The tungsten ore slurry is transported by gravity to the tungsten ore pump pool, with a raw ore mass percentage concentration of 35-41%.

[0009] S2, Raw Ore Classification and Regrinding: The tungsten ore slurry in step S1 is pumped to a hydrocyclone for classification, separating it into overflow and underflow. The qualified fine-grained product of the overflow enters the raw ore separation tank as the raw ore for subsequent roughing operations. The coarse-grained or intergrowth product of the underflow enters the regrinding mill for regrinding to ensure the dissociation of intergrowths. The regrinded ore discharge is returned to the tungsten ore pump pool for further classification, forming a closed-circuit grinding.

[0010] S3, Tungsten roughing operation: After adding the combined collector to the hydrocyclone overflow in step 2, it enters the roughing flotation column for one roughing operation to obtain tungsten rough concentrate and roughing tailings. The tungsten rough concentrate is transported to the rough concentrate foam box, and the roughing tailings enter the scavenging operation. Preferably, both the roughing and scavenging processes include two sets of parallel equipment. In S2, the raw ore slurry in the raw ore slurry box is divided into two streams and enters the corresponding roughing equipment respectively.

[0011] S4. Tungsten crude concentrate concentration: In step S3, the crude concentrate in the foam box is transported by gravity through a pipeline to a Φ30m thickener for concentration, resulting in thickener underflow and overflow. The thickener overflow is transported to a pre-concentration column for re-selection and recovery. The pre-concentration column concentrate is returned to the thickener, and the pre-concentration column tailings are collected into the final tailings.

[0012] S5. Heating and De-drug Removal: The thickener underflow in step S4 is a concentrated tungsten crude concentrate slurry with a mass percentage concentration of 60%-70%. The concentrated slurry is pumped into a heated mixing tank and heated with steam. The slurry temperature is raised to 60°C, and a de-drug agent is added. Then, the slurry temperature is raised to 85°C under vigorous stirring. Heating is stopped, and the temperature is maintained for at least 45 minutes.

[0013] S6. Slurry preparation and roughing operation: After the slurry is heated and de-treated in step S5, it is pumped to the slurry preparation tank and then clean water is added to prepare the slurry. The mass percentage concentration of the slurry after preparation is 25%-30%. The slurry after preparation is first roughed, and the roughed foam enters the cleaning stage. The roughed tailings are then cleaned.

[0014] S7. Fine Refinement Operation: The fine refinement process includes five stages: Fine Refinement I, Fine Refinement II, Fine Refinement III, Fine Refinement IV, and Fine Refinement V, which are set up in series. After five fine refinements, the final tungsten concentrate is obtained. The concentrate obtained from each fine refinement enters the next fine refinement stage, and the tailings obtained from each fine refinement stage are returned to the previous fine refinement stage for further separation.

[0015] S8. Fine Scavenging Operation: Step S6, fine scavenging operation, includes fine scavenging I, fine scavenging II, and fine scavenging III connected in series. The concentrate from fine scavenging I is returned to the roughing operation. The tailings from fine scavenging I are processed by fine scavenging II. The tailings from fine scavenging II are processed by fine scavenging III. The concentrates from fine scavenging II and fine scavenging III are returned sequentially to the previous scavenging operation for further separation. The tailings from fine scavenging III are discarded as the final cleaned tailings.

[0016] Furthermore, in the beneficiation method for recovering ultra-low grade scheelite from molybdenum tailings, step S3 includes scavenging operations consisting of scavenging I and scavenging II connected in series. After adding an appropriate amount of combined collector to the roughing tailings, scavenging I is performed. The concentrate from scavenging I is returned to the roughing process for further separation. The tailings from scavenging I are then processed in scavenging II. The concentrate from scavenging II is returned to the previous stage of the process. The tailings from scavenging II are then discarded as the final tailings.

[0017] Furthermore, in the beneficiation method for recovering ultra-low grade scheelite from molybdenum tailings, the combined collector in step S3 of the roughing and scavenging operations is a fatty acid, including reagents FX-8 and FX-E mixed in a mass ratio of 6:1. The combined collector dosage in the roughing operation is 200-360 g / t, and the combined collector dosage in the scavenging operation is 40-80 g / t.

[0018] Furthermore, in the beneficiation method for recovering ultra-low grade scheelite from molybdenum tailings, in step S1, sodium carbonate is used as a modifier in the slurry pretreatment to adjust the pH value of the slurry to 9.5-10, and the amount of modifier used is 1500-2500 g / t; the inhibitor is a mixture of water glass and SG, wherein the amount of water glass used is 1000-2200 g / t, and the main component of SG is a composite phosphate, and the amount used is 40-100 g / t.

[0019] Furthermore, in the beneficiation method for recovering ultra-low grade scheelite from molybdenum tailings, the mass percentage of particles with a fineness of -0.074 mm in the overflow material in step S2 is 59-64%.

[0020] Furthermore, in the beneficiation method for recovering ultra-low grade scheelite from molybdenum tailings, a combined collector is added to the S4 pre-cleaning column at a dosage of 10 g / t.

[0021] Furthermore, in the beneficiation method for recovering ultra-low grade scheelite from molybdenum tailings, the amount of desiccant used in the S5 heating and desiccant stage is 35-50 kg / ton of rough concentrate.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention relates to a beneficiation method for recovering ultra-low-grade scheelite from molybdenum tailings. Targeting refractory scheelite with severe alteration and mudding, the method employs pre-slurry conditioning, enhanced pretreatment with reagents moved forward, followed by grinding and classification of the raw ore. A combination of collectors is used to synergistically enhance the recovery of refractory scheelite, ultimately yielding a tungsten concentrate with a grade >26%. The overall actual recovery rate reaches 77%. This invention's process achieves full recovery and utilization of refractory scheelite resources in tailings, while reducing the operating costs of refractory ore recovery, creating considerable economic and social benefits.

[0024] In this invention, the modifier sodium carbonate is moved forward to eliminate the interference of calcium and magnesium ions in the water in advance, enhance the moderating effect on the pulp, and create a suitable pulp alkalinity for flotation. The inhibitor water glass and SG are added in advance at the front-end operation point before the grinding process, which prolongs the reaction time of the reagents, allowing the inhibitor to interact more fully with the mineral surface, inhibit gangue in advance, and help improve the grade of tungsten rough concentrate, creating good conditions for subsequent beneficiation.

[0025] In this invention, the tungsten ore is preferentially graded and regrinded, which helps to liberate the intergrowth scheelite, increases the flotation reagent binding sites on the scheelite surface, and makes it easier for the scheelite to selectively adsorb with the collector. This reduces the decrease in concentrate grade caused by the flotation of gangue carried by the intergrowth. At the same time, it avoids the over-grinding of the already liberated fine-grained useful minerals and gangue minerals, which would generate secondary slime, deteriorate the flotation environment, reduce the consumption of flotation reagents, and achieve effective collection of fine-grained scheelite. This has a significant effect on improving the roughing recovery rate.

[0026] In this invention, the combination of collectors FX-8 and FX-E utilizes the synergistic effect of different collectors to enhance the collection ability and selectivity for the target mineral, ultimately resulting in a significant increase in the recovery rate of scheelite flotation. Attached Figure Description

[0027] Figure 1 This is a process flow diagram of the mineral processing method for recovering ultra-low grade scheelite from molybdenum tailings according to the present invention.

[0028] Figure 2 This is a flowchart comparing examples 1 and 2. Detailed Implementation

[0029] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the scope of protection of the present invention is not limited to the following embodiments.

[0030] In this invention, FX-8, FX-E and SG are all commercially available reagents purchased from Luoyang Zhenbei Industry and Trade Co., Ltd. FX-8 and FX-E are fatty acid collectors, and the main component of SG is a combination phosphate. Example 1

[0031] In this embodiment, the molybdenum tailings from sulfur flotation at a large mineral processing plant in Henan Province contained 0.070% WO3, 20.49% CaF2, and 36.50% CaCO3. The valuable metals in the tailings were mainly scheelite, pyrite, and magnetite, while the gangue consisted primarily of fluorite, calcite, and apatite. The specific steps of the mineral processing method are as follows:

[0032] S1: The tungsten ore slurry concentration is 36%, and the fineness of -0.074mm accounts for 61.2%. The slurry is transported by gravity to the tungsten ore pump pool. Sodium carbonate, water glass and SG are added to the ore pump pool as modifiers, at dosages of 1900g / t, 1000g / t and 60g / t respectively, and the pH value is adjusted to 9.5.

[0033] S2: Tungsten ore with added modifiers and inhibitors is classified by hydrocyclones. The overflow enters the ore slurry box, the underflow enters the regrinding mill for fine grinding, and the refrinding discharge is returned to the tungsten ore pump pool to form a closed-circuit grinding.

[0034] S3: The hydrocyclone overflow slurry entering the flotation column has a concentration of 34.75% and a fineness of -0.074mm accounts for 64.83%. At room temperature, a process of one roughing and two scavenging is used to recover scheelite. 320g / t, 40g / t and 10g / t collector FX-8 are added to the roughing, scavenging I and scavenging II respectively.

[0035] S4: The rough concentrate obtained in step S3 is transported to a Φ30m thickener for concentration. After concentration, the slurry concentration is 64%.

[0036] S5: Pump the concentrated crude concentrate into a heated mixing tank, heat and remove reagents using steam heating. When the slurry temperature reaches 60℃, add the reagent remover at a dosage of 43kg / ton of crude concentrate. Heat to 85℃ under strong stirring and then stop heating. Keep the slurry at the temperature for 50 minutes after heating is stopped.

[0037] S6~S8: After the slurry is heated and de-treated in step S5, it is pumped to the slurry mixing tank and then clean water is added to adjust the slurry concentration to 25%-30%. The slurry after adjustment is first roughed out, and the roughed foam enters the cleaning stage for five cleaning processes. The roughed tailings are then cleaned out three times.

[0038] Using the beneficiation method of this embodiment, tungsten rough concentrate with WO3 grade > 1.0% was obtained, with a roughing recovery rate of 76.90% and an overall actual tungsten recovery rate of 67.20%, ultimately yielding tungsten concentrate with WO3 grade > 26%. Example 2

[0039] In this embodiment, the molybdenum tailings from sulfur flotation at a large mineral processing plant in Henan Province contained 0.089% WO3, 25.49% CaF2, and 34.79% CaCO3. The valuable metals in the tailings were mainly scheelite and magnetite, while the gangue consisted primarily of calcium-bearing minerals such as calcite, andradite, quartz, and chlorite. The specific steps of the mineral processing method are as follows:

[0040] S1: The slurry is pretreated before scheelite flotation. 2300g / t of sodium carbonate is added to the feed pipe of the flotation column in the last scavenging of sulfur in the upstream process to adjust the pH of the slurry to 9.5-10. Water glass and SG are added to the tailings box of the sulfur scavenging operation at a dosage of 1400g / t and 60g / t, respectively.

[0041] S2: The pretreated tungsten ore is classified by a hydrocyclone. The overflow enters the ore slurry tank, the underflow enters the regrinding mill for fine grinding, and the refrinding discharge is returned to the tungsten ore pump pool.

[0042] S3: The tungsten ore overflow from the hydrocyclone entering the flotation column has a fineness of -0.074mm accounting for 61.57%. At room temperature, the "one roughing and two scavenging" process is used to recover scheelite. 280g / t and 70g / t collector FX-8 are added to the roughing and scavenging I processes, respectively.

[0043] S4: The rough concentrate from step S3 is transported to a Φ30m thickener for concentration. After concentration, the pulp concentration is 68.36%.

[0044] S5: The concentrated crude concentrate is pumped into a heated mixing tank for heating and de-drug removal. Steam heating is used. When the slurry temperature reaches 60℃, de-drug agent is added at a dosage of 40kg / ton of crude concentrate. Heating is stopped when the temperature reaches 85℃ under strong stirring. The slurry is kept warm for 50 minutes after heating is stopped.

[0045] S6~S8: After the slurry is heated and de-treated in step S5, it is pumped to the slurry mixing tank and then clean water is added to adjust the slurry concentration to 25%-30%. The slurry after adjustment is first roughed out, and the roughed foam enters the cleaning stage for five cleaning processes. The roughed tailings are then cleaned out three times.

[0046] Using the beneficiation method of this embodiment, tungsten rough concentrate with WO3 grade >1.0% was obtained, with a roughing recovery rate of 80.0% and an overall actual tungsten recovery rate of 76.90%, ultimately yielding tungsten concentrate with WO3 grade >26%. Example 3

[0047] The molybdenum tailings from sulfur flotation at a large mineral processing plant in Henan Province, processed in this embodiment, contained 0.062% WO3, 18.43% CaF2, and 35.49% CaCO3. Valuable metals in the tailings were mainly scheelite, pyrite, and magnetite. The gangue minerals were diverse, including magnetic gangue minerals such as garnet (mainly andradite), pyroxene, and amphibole, followed by non-magnetic gangue minerals such as quartz, carbonate minerals, feldspar, fluorite, and apatite, as well as small amounts of chlorite and talc. The sample had a high calcium mineral content. The following methods were employed: Figure 1 The mineral processing method shown in the process flow diagram has the following specific steps:

[0048] S1: The slurry is pretreated before scheelite flotation. 2000g / t of sodium carbonate is added to the slurry feed pipe of the flotation column in the last scavenging of sulfur in the upstream process to adjust the pH of the slurry to 9.5-10. Water glass and SG are added to the tailings box of the sulfur scavenging operation at a dosage of 1800g / t and 60g / t, respectively.

[0049] S2: The pretreated tungsten ore is classified by a hydrocyclone, the overflow enters the ore slurry box, the underflow enters the regrinding mill for fine grinding, and the refrinding discharge is returned to the tungsten ore pump pool to form a closed-circuit grinding.

[0050] S3: The tungsten ore feed into the hydrocyclone of the flotation column has a fineness of -0.074mm, accounting for 62.08%. At room temperature, the "one roughing and two scavenging" process is used to recover scheelite. 280g / t and 60g / t of combined collector are added to the roughing and scavenging I processes, respectively. The mass ratio of FX-8 and FX-E in the combined collector is 6:1.

[0051] S4: The rough concentrate from step S3 is transported to a Φ30m thickener for concentration. After concentration, the pulp concentration is 67.68%.

[0052] S5: The concentrated crude concentrate is pumped into a heated mixing tank for heating and de-drug removal. Steam heating is used. When the slurry temperature reaches 60℃, de-drug agent is added at a dosage of 40kg / ton of crude concentrate. Heating is stopped when the temperature reaches 85℃ under strong stirring. The slurry is kept warm for 50 minutes after heating is stopped.

[0053] S6~S8: After the slurry is heated and de-treated in step S5, it is pumped to the slurry mixing tank and then clean water is added to adjust the slurry concentration to 25%-30%. The slurry after adjustment is first roughed out, and the roughed foam enters the cleaning stage for five cleaning processes. The roughed tailings are then cleaned out three times.

[0054] Using the beneficiation method of this embodiment, tungsten rough concentrate with WO3 grade > 1.0% was obtained, with a roughing recovery rate of 83.13% and an overall actual tungsten recovery rate of 77.64%, ultimately yielding tungsten concentrate with WO3 grade > 26%. Example 4

[0055] The molybdenum tailings from sulfur flotation at a large mineral processing plant in Henan Province processed in this implementation method contained WO3 content of 0.095%-0.115%, CaF2 content of 20.49%, and CaCO3 content of 36.50%. Valuable metals in the tailings mainly consisted of scheelite, pyrite, and magnetite, while gangue primarily included fluorite, calcite, and chlorite. The following method was adopted... Figure 1 The mineral processing method shown in the process flow diagram has the following specific steps:

[0056] S1: The slurry is pretreated before scheelite flotation. 2200g / t of sodium carbonate is added to the feed pipe of the flotation column in the last scavenging of sulfur in the upstream process to adjust the pH of the slurry to 9.5-10. Water glass and SG are added to the tailings box of the sulfur scavenging operation at a dosage of 1500g / t and 60g / t, respectively.

[0057] S2: The pretreated tungsten ore is classified by a hydrocyclone. The overflow fineness of -0.074mm accounts for 62.74%. The overflow enters the raw ore slurry box, and the underflow enters the regrinding mill for fine grinding. The regrinded ore discharge is returned to the tungsten ore pump pool to form a closed-circuit grinding.

[0058] S3: The tungsten ore overflow from the hydrocyclone entering the flotation column has a fineness of -0.074mm accounting for 61.57%. At room temperature, the "one roughing and two scavenging" process is used to recover scheelite. 240g / t and 80g / t of combined collector are added to the roughing and scavenging I processes, respectively.

[0059] S4: The rough concentrate from step S3 is transported to a Φ30m thickener for concentration. After concentration, the pulp concentration is 62.81%.

[0060] S5: The concentrated crude concentrate is pumped into a heated mixing tank for heating and de-drug removal. Steam heating is used. When the slurry temperature reaches 60℃, de-drug agent is added at a dosage of 42kg / ton of crude concentrate. Heating is stopped when the temperature reaches 85℃ under strong stirring. The slurry is kept warm for 50 minutes after heating is stopped.

[0061] S6~S8: After the slurry is heated and de-treated in step S5, it is pumped to the slurry mixing tank and then clean water is added to adjust the slurry concentration to 25%-30%. The slurry after adjustment is first roughed out, and the roughed foam enters the cleaning stage for five cleaning processes. The roughed tailings are then cleaned out three times.

[0062] The production index results corresponding to different proportions of FX-E in the combined collector in step S3 are shown in Table 1.

[0063] Table 1. Production index results for different combinations of collectors

[0064]

[0065] According to the data in Table 1, as the proportion of FX-E in the combined collector continues to increase, the grade of tungsten rough concentrate tends to decrease, and the theoretical recovery rate of roughing is reduced. Therefore, the proportion of FX-E in the combined collector is determined to be 14.29%, that is, the ratio of FX-8 to FX-E in the combined collector is 6:1.

[0066] Comparative Example 1

[0067] The molybdenum tailings from sulfur flotation at a large mineral processing plant in Henan Province, processed in this implementation, contained 0.095% WO3, 21.49% CaF2, and 38.63% CaCO3. Valuable metals in the tailings were mainly scheelite, pyrite, and magnetite. Gangue primarily consisted of fluorite, calcite, and apatite, with some ores showing severe alteration and chloritization. The following method was adopted... Figure 2 The mineral processing method shown in the process flow diagram has the following specific steps:

[0068] S1: The concentration of tungsten ore slurry is 34%, and the fineness of -0.074mm accounts for 58.2%. The slurry is transported by gravity to the tungsten ore pump pool. Sodium carbonate and water glass and SG are added to the ore pump pool as modifiers, with dosages of 3000g / t, 500g / t and 30g / t respectively. The pH value of the ore slurry is adjusted to 9.2.

[0069] S2: At room temperature, the "one roughing and two scavenging" process is used to recover scheelite. 360g / t, 40g / t and 10g / t collector FX-8 are added to the roughing, scavenging I and scavenging II processes, respectively.

[0070] S3: The rough concentrate obtained in step S2 is transported to a Φ30m thickener for concentration. The concentrated rough concentrate is then pumped into a heated mixing tank. The slurry concentration is measured to be 60%, and the reagent dosage is 50 kg / ton of rough concentrate. Scheelite is recovered using a heated cleaning method, consisting of one roughing, five cleaning, and three fine scavenging processes.

[0071] Using the beneficiation method described in this comparative example, a tungsten rough concentrate with a WO3 grade of 0.89% was obtained. The theoretical recovery rate of roughing was 68.79%, the actual comprehensive tungsten recovery rate was 65.62%, and the final tungsten concentrate had a WO3 grade of over 25%.

[0072] Comparative Example 2

[0073] The same batch of flotation tailings as in Example 1 was used in Comparative Example 2, except that the process steps of Comparative Example 1 were used in Comparative Example 2.

[0074] In this embodiment, the molybdenum tailings from sulfur flotation at a large mineral processing plant in Henan Province contained 0.070% WO3, 20.49% CaF2, and 36.50% CaCO3. The valuable metals in the tailings were mainly scheelite, pyrite, and magnetite, while the gangue consisted primarily of fluorite, calcite, and apatite. The specific steps of the mineral processing method are as follows:

[0075] S1: The concentration of tungsten ore slurry is 34%, and the fineness of -0.074mm accounts for 58.2%. The slurry is transported by gravity to the tungsten ore pump pool. Sodium carbonate, water glass and SG are added to the ore pump pool as adjusters, at a dosage of 1900g / t, 1000g / t and 60g / t respectively, to adjust the pH value of the ore slurry to 9.5.

[0076] S2: At room temperature, the "one roughing and two scavenging" process is used to recover scheelite. 320g / t, 40g / t and 10g / t collector FX-8 are added to the roughing, scavenging I and scavenging II processes, respectively.

[0077] S3: The rough concentrate obtained in step S2 is transported to a Φ30m thickener for concentration. The concentrated rough concentrate is then pumped into a heated mixing tank. The slurry concentration is measured to be 60%, and the reagent dosage is 50 kg / ton of rough concentrate. Scheelite is recovered using a heated cleaning method, consisting of one roughing, five cleaning, and three fine scavenging processes.

[0078] Using the beneficiation method of this comparative example, tungsten rough concentrate with WO3 grade >1.0% was obtained, with a theoretical recovery rate of 71.27% in roughing, an actual comprehensive tungsten recovery rate of 66.28%, and a final tungsten concentrate with WO3 grade of over 25%.

[0079] Comparing Comparative Example 2 with Example 1, it can be seen that in Example 1, by adding a classification and regrinding process, the roughing recovery rate increased from 71.27% to 76.90%, an increase of 5.63 percentage points. The overall actual tungsten recovery rate increased from 66.28% to 67.20%, an increase of nearly 1 percentage point. Finally, the WO3 grade of the tungsten concentrate also increased by 1 percentage point.

[0080] Comparative Example 3

[0081] The same batch of flotation tailings as in Example 2 was used in Comparative Example 3, except that the process steps of Example 1 were used.

[0082] In this embodiment, the molybdenum tailings from sulfur flotation at a large mineral processing plant in Henan Province contained 0.089% WO3, 25.49% CaF2, and 34.79% CaCO3. The valuable metals in the tailings were mainly scheelite and magnetite, while the gangue consisted primarily of calcium-bearing minerals such as calcite, andradite, quartz, and chlorite. The specific steps of the mineral processing method are as follows:

[0083] S1: The tungsten ore slurry concentration is 36%, and the fineness of -0.074mm accounts for 61.2%. The slurry is gravity-fed to the tungsten ore pump pool. Sodium carbonate, water glass and SG are added to the ore pump pool at dosages of 2300g / t, 1400g / t and 60g / t respectively, and the pH value is adjusted to 9.5-10.

[0084] S2: Tungsten ore with added modifiers and inhibitors is classified by hydrocyclones. The overflow enters the ore slurry box, the underflow enters the regrinding mill for fine grinding, and the refrinding discharge is returned to the tungsten ore pump pool to form a closed-circuit grinding.

[0085] S3: The hydrocyclone overflow slurry entering the flotation column has a concentration of 34.75% and a fineness of -0.074mm of 64.83%. At room temperature, a process of one roughing and two scavenging is used to recover scheelite. 280g / t, 70g / t and 10g / t collector FX-8 are added to the roughing, scavenging I and scavenging II respectively.

[0086] S4: The rough concentrate obtained in step S3 is transported to a Φ30m thickener for concentration. After concentration, the slurry concentration is 64%.

[0087] S5: Pump the concentrated crude concentrate into a heated mixing tank, heat and remove reagents using steam heating. When the slurry temperature reaches 60℃, add the reagent remover at a dosage of 43kg / ton of crude concentrate. Heat to 85℃ under strong stirring and then stop heating. Keep the slurry at the temperature for 50 minutes after heating is stopped.

[0088] S6~S8: After the slurry is heated and de-treated in step S5, it is pumped to the slurry mixing tank and then clean water is added to adjust the slurry concentration to 25%-30%. The slurry after adjustment is first roughed out, and the roughed foam enters the cleaning stage for five cleaning processes. The roughed tailings are then cleaned out three times.

[0089] Using the beneficiation method of this comparative example, a tungsten rough concentrate with a WO3 grade >1.0% was obtained. The theoretical recovery rate of roughing was 78.55%, the actual comprehensive tungsten recovery rate was 73.95%, and the final tungsten concentrate had a WO3 grade of over 26%.

[0090] Comparing Comparative Example 3 with Example 2, it can be seen that in Example 2, by moving the reagent forward in step S1 to enhance the pretreatment, the roughing recovery rate increased from 78.55% to 80.0%, an increase of 1.45 percentage points, and the overall actual tungsten recovery rate increased from 73.95% to 76.90%, an increase of nearly 3 percentage points.

[0091] Comparative Example 4

[0092] The same batch of flotation tailings as in Example 3 was used in Comparative Example 4, except that the process steps of Example 2 were used.

[0093] The molybdenum tailings from a large mineral processing plant in Henan Province, processed in this study, contained 0.062% WO3, 18.43% CaF2, and 35.49% CaCO3. Valuable metals in the tailings were mainly scheelite, pyrite, and magnetite. The gangue minerals were diverse, including magnetic gangue minerals such as garnet (mainly andradite), pyroxene, and amphibole, followed by non-magnetic gangue minerals such as quartz, carbonate minerals, feldspar, fluorite, and apatite, as well as small amounts of chlorite and talc. The sample had a relatively high calcium content. The specific steps of the mineral processing method are as follows:

[0094] S1: The slurry is pretreated before scheelite flotation. 2000g / t of sodium carbonate is added to the feed pipe of the flotation column in the last scavenging of sulfur in the upstream process to adjust the pH of the slurry to 9.5-10. Water glass and SG are added to the tailings box of the sulfur scavenging operation at a dosage of 1800g / t and 60g / t, respectively.

[0095] S2: The pretreated tungsten ore is classified by a hydrocyclone. The overflow enters the ore slurry tank, the underflow enters the regrinding mill for fine grinding, and the refrinding discharge is returned to the tungsten ore pump pool.

[0096] S3: The tungsten ore overflow from the hydrocyclone entering the flotation column has a fineness of -0.074mm accounting for 61.57%. At room temperature, the "one roughing and two scavenging" process is used to recover scheelite. 280g / t and 60g / t collector FX-8 are added to the roughing and scavenging I processes, respectively.

[0097] S4: The rough concentrate from step S3 is transported to a Φ30m thickener for concentration. After concentration, the pulp concentration is 68.36%.

[0098] S5: The concentrated crude concentrate is pumped into a heated mixing tank for heating and de-drug removal. Steam heating is used. When the slurry temperature reaches 60℃, de-drug agent is added at a dosage of 40kg / ton of crude concentrate. Heating is stopped when the temperature reaches 85℃ under strong stirring. The slurry is kept warm for 50 minutes after heating is stopped.

[0099] S6~S8: After the slurry is heated and de-treated in step S5, it is pumped to the slurry mixing tank and then clean water is added to adjust the slurry concentration to 25%-30%. The slurry after adjustment is first roughed out, and the roughed foam enters the cleaning stage for five cleaning processes. The roughed tailings are then cleaned out three times.

[0100] Using the beneficiation method of this comparative example, a tungsten rough concentrate with a WO3 grade >1.0% was obtained, with a theoretical recovery rate of 79.97% in roughing, an actual comprehensive tungsten recovery rate of 76.87%, and a final tungsten concentrate with a WO3 grade of over 26%.

[0101] Comparing Comparative Example 4 with Example 3, it can be seen that in Example 3, by using a combined collector in step S3, the roughing recovery rate increased from 79.97% to 83.13%, an increase of 3.16 percentage points, and the overall actual tungsten recovery rate increased from 76.87% to 77.64%, an increase of nearly 1 percentage point.

[0102] In summary, the present invention provides a beneficiation method for recovering ultra-low-grade scheelite from molybdenum tailings. For refractory scheelite with severe alteration and mudding, the method employs pre-slurry conditioning, enhanced pretreatment with reagents moved forward, followed by grinding and classification of the raw ore. By combining collectors to synergistically enhance the recovery of refractory scheelite, a tungsten concentrate with a grade >26% is finally obtained, achieving a comprehensive actual recovery rate of 77%. The process of this invention achieves full recovery and utilization of refractory scheelite resources in tailings, while reducing the operating costs of refractory ore recovery, creating considerable economic and social benefits.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A beneficiation method for recovering ultra-low-grade scheelite from molybdenum tailings, characterized in that, Specifically, the following steps are included: S1. Slurry Pretreatment: Sodium carbonate, a scheelite modifier, is added to the feed pipe of the flotation column in the final scavenging stage of upstream sulfur beneficiation. An inhibitor is added to the tailings box of the upstream sulfur scavenging operation. The sodium carbonate modifier is moved forward to eliminate interference from calcium and magnesium ions in the water, enhancing the conditioning effect on the slurry and creating a suitable slurry alkalinity for flotation. The inhibitor is added before grinding to achieve enhanced pretreatment by moving the reagents forward. The tungsten ore slurry is transported by gravity through pipelines to the tungsten ore pump pool, with a raw ore mass percentage concentration of 35-41%. S2, Raw Ore Classification and Regrinding: The tungsten ore slurry in step S1 is pumped to a hydrocyclone for classification, separating it into overflow and underflow. The qualified fine-grained product of the overflow enters the raw ore separation tank as the raw ore for subsequent roughing operations. The coarse-grained or intergrowth product of the underflow enters the regrinding mill for regrinding to ensure the dissociation of intergrowths. The regrinded ore discharge is returned to the tungsten ore pump pool for further classification, forming a closed-circuit grinding. S3, Tungsten roughing operation: After adding the combined collector to the hydrocyclone overflow in step 2, it enters the roughing flotation column for one roughing operation to obtain tungsten rough concentrate and roughing tailings. The tungsten rough concentrate is transported to the rough concentrate foam box, and the roughing tailings enter the scavenging operation. S4. Tungsten crude concentrate concentration: In step S3, the crude concentrate in the foam box is transported by gravity through a pipeline to a Φ30m thickener for concentration, resulting in thickener underflow and overflow. The thickener overflow is transported to a pre-concentration column for re-selection and recovery. The pre-concentration column concentrate is returned to the thickener, and the pre-concentration column tailings are collected into the final tailings. S5. Heating and De-drug Removal: The thickener underflow in step S4 is a concentrated tungsten crude concentrate slurry with a mass percentage concentration of 60%-70%. The concentrated slurry is pumped into a heated mixing tank and heated with steam. The slurry temperature is raised to 60°C, and a de-drug agent is added. Then, the slurry temperature is raised to 85°C under vigorous stirring. Heating is stopped, and the temperature is maintained for at least 45 minutes. S6. Slurry preparation and roughing operation: After the slurry is heated and de-treated in step S5, it is pumped to the slurry preparation tank and then clean water is added to prepare the slurry. The mass percentage concentration of the slurry after preparation is 25%-30%. The slurry after preparation is first roughed, and the roughed foam enters the cleaning stage. The roughed tailings are then cleaned. S7. Fine Refinement Operation: The fine refinement process includes five stages: Fine Refinement I, Fine Refinement II, Fine Refinement III, Fine Refinement IV, and Fine Refinement V, which are set up in series. After five fine refinements, the final tungsten concentrate is obtained. The concentrate obtained from each fine refinement enters the next fine refinement stage, and the tailings obtained from each fine refinement stage are returned to the previous fine refinement stage for further separation. S8. Fine Scavenging Operation: Step S6, fine scavenging operation, includes fine scavenging I, fine scavenging II, and fine scavenging III connected in series. The concentrate from fine scavenging I is returned to the roughing operation. The tailings from fine scavenging I are processed by fine scavenging II. The tailings from fine scavenging II are processed by fine scavenging III. The concentrates from fine scavenging II and fine scavenging III are returned sequentially to the previous scavenging operation for further separation. The tailings from fine scavenging III are discarded as the final cleaned tailings.

2. The beneficiation method for recovering ultra-low-grade scheelite from molybdenum tailings according to claim 1, characterized in that, Step S3 includes scavenging operations consisting of scavenging I and scavenging II connected in series. After adding an appropriate amount of combined collector to the roughing tailings, scavenging I is performed. The concentrate from scavenging I is returned to the roughing stage for further separation. The tailings from scavenging I are then processed into scavenging II. The concentrate from scavenging II is returned to the previous stage and the tailings from scavenging II are discarded as the final tailings.

3. The beneficiation method for recovering ultra-low-grade scheelite from molybdenum tailings according to claim 2, characterized in that, In step S1, sodium carbonate is used as a modifier in the slurry pretreatment to adjust the pH value of the slurry to 9.5-10, and the dosage of the modifier is 1500-2500 g / t. The inhibitor is a mixture of water glass and SG, wherein the dosage of water glass is 1000-2200 g / t, and the main component of SG is a composite phosphate, with a dosage of 40-100 g / t.

4. The beneficiation method for recovering ultra-low-grade scheelite from molybdenum tailings according to claim 2, characterized in that, In step S2, the mass percentage of particles with a fineness of -0.074 mm in the overflow is 59-64%.

5. The beneficiation method for recovering ultra-low-grade scheelite from molybdenum tailings according to claim 2, characterized in that, In the S5 heating and de-agenting process, the amount of de-agent used is 35-50 kg / ton of rough concentrate.

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