A flotation regulator for refractory scheelite and a flotation process thereof

Abstract

The application discloses a flotation regulator combination for refractory scheelite and a flotation process thereof, and belongs to the technical field of mineral processing, wherein the regulator comprises oxalic acid as a regulator, lead nitrate as an activator and GY chelating collector as a collector; the flotation process adopts a process of one roughing, one scavenging and three cleaning, that is, after raw ore is ground, oxalic acid is added to adjust the pH of the ore slurry, lead nitrate is added to activate the surface of scheelite, GY collector and 2# oil are added to perform roughing; the tailings of roughing are subjected to one scavenging; the roughing concentrate is subjected to three cleaning, and finally, scheelite concentrate is obtained. The application is aimed at the refractory scheelite with fine embedded particle size and high calcium content, and utilizes the oxalic acid to selectively inhibit the gangue minerals such as calcite and clean the surface of scheelite, so as to realize effective separation in cooperation with the GY collector.

Description

Technical Field

[0001] This invention belongs to the technical field of mineral processing, specifically relating to a flotation modifier for refractory scheelite and its flotation process. Background Technology

[0002] Scheelite (CaWO4) is an important tungsten mineral resource, and its flotation separation is a key technical step in obtaining high-grade tungsten concentrate. Scheelite often occurs in association with calcium-bearing gangue minerals such as calcite (CaCO3) and fluorite (CaF2). These gangue minerals and scheelite both contain calcium ion active sites, have highly similar surface chemical properties, and similar floatability, making flotation separation extremely difficult.

[0003] Currently, the commonly used modifiers in scheelite flotation are mainly inorganic depressants such as sodium carbonate and water glass, while collectors are primarily fatty acid reagents such as oxidized paraffin soap and 731. However, these conventional reagent systems have significant shortcomings when dealing with certain types of difficult-to-process scheelite ores. For example, in a scheelite mine in Guangxi, the main metallic minerals are magnetite and pyrite, and the non-metallic minerals are apatite, dolomite, mica, calcite, and talc. The raw ore contains only 0.56% WO3, and the gangue minerals are closely intergrown with the scheelite, with fine particle size. When using conventional sodium carbonate as a modifier, the flotation effect is extremely poor, with almost no significant difference in WO3 grade between the raw ore, concentrate, and tailings, making effective separation impossible.

[0004] Furthermore, the oxidized paraffin soap collectors used in traditional processes typically require heating, and these agents are somewhat toxic, posing potential hazards to the environment and operators, thus limiting their application. While fatty acid collectors such as 731 are less expensive, they lack selectivity when processing ores with high calcium gangue content, easily leading to low concentrate grades.

[0005] In recent years, organic inhibitors have attracted attention due to their diverse structures and ease of selective inhibition. Oxalic acid, as a small-molecule organic acid, contains two polar hydrophilic carboxyl (-COOH) groups in its molecule, which can react with CaO on the surface of calcium-bearing gangue minerals such as calcite. 2+ Chelation occurs, forming a hydrophilic surface that inhibits the flotation of gangue minerals. Studies also show a synergistic effect when oxalic acid and water glass are used together: oxalic acid promotes the formation and polymerization of silica molecules, forming fine silica particles, while simultaneously dissociating itself to release more C2O4. 2- The two complement and reinforce each other, enhancing the inhibitory effect of the drug on gangue minerals.

[0006] On the other hand, GY chelating collector is a novel tungsten ore collector developed in recent years. It is composed of benzo[a]hydroxyxamic acid and fatty acid collectors, and has good collecting performance for both wolframite and scheelite. Lead nitrate is a commonly used activator in tungsten ore flotation. After hydrolysis in the pulp, it forms an active zone, which allows the anionic groups of the collector to form chemical adsorption on the mineral surface, thereby improving the collecting effect.

[0007] However, there are no reports on the application of oxalic acid as a modifier in combination with GY collector and lead nitrate activator for the treatment of specific refractory scheelite ores. In existing technologies, oxalic acid is mainly used as a component of combined inhibitors for the separation of tungsten-fluorite ores or high-calcium ores, while the GY method is mainly applied to the flotation of mixed tungsten-white and spruce ores such as those from Shizhuyuan. Developing an effective modifier combination and supporting flotation process for a specific refractory scheelite ore in Guangxi, characterized by calcite as the main gangue, fine particle size, and ineffectiveness of conventional modifiers, has significant industrial application value. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a flotation modifier for refractory scheelite and its flotation process to solve the problems mentioned in the background art or achieve better technical effects.

[0009] In order to solve the above-mentioned technical problems, the inventors derived the technical solution of the present invention through practice and summary. The present invention discloses a flotation modifier for refractory scheelite, comprising oxalic acid as a modifier, lead nitrate as an activator, and GY chelating collector as a collector.

[0010] The amount of oxalic acid used in the flotation roughing operation is 150~300g / t, the amount of lead nitrate is 600~1000g / t, and the amount of GY chelating collector is 300~500g / t.

[0011] Furthermore, the flotation modifier also includes a frother, which is No. 2 oil, and the dosage is 20~60g / t.

[0012] Furthermore, the flotation modifier is: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0013] Furthermore, the flotation process for refractory scheelite using any of the flotation modifiers described above comprises the following steps:

[0014] S1: Grind the refractory scheelite ore to -0.074mm, accounting for 65%~85%;

[0015] S2: Add oxalic acid to the slurry as a modifier. The reaction time of oxalic acid with the slurry is 2-5 minutes, and adjust the pH of the slurry to 6.0-8.0.

[0016] S3: Add lead nitrate to the slurry as an activator;

[0017] S4: Add GY chelating collector and No. 2 oil frother to the slurry for roughing operation;

[0018] S5: Perform scavenging on the roughing tailings, and return the scavenged concentrate to the roughing operation;

[0019] S6: Perform at least three fine-refinement operations on the rough concentrate, and return the middlings from each fine-refinement operation to the previous operation in sequence to finally obtain scheelite concentrate.

[0020] Furthermore, the refractory scheelite is a scheelite with a WO3 grade of 0.3%~1.0% and a calcite content of ≥15%.

[0021] Furthermore, the refractory scheelite is a scheelite ore with a WO3 grade of 0.5%~0.6% and a total content of calcite and dolomite in gangue minerals of ≥20%.

[0022] Furthermore, in S4, the amount of oxalic acid used in the roughing operation is 150~300g / t, the amount of lead nitrate is 600~1000g / t, the amount of GY chelating collector is 300~500g / t, and the amount of No. 2 oil is 20~60g / t.

[0023] Furthermore, in S5, the scavenging operation is a single scavenging operation, during which 50~150g / t of GY chelating collector is added.

[0024] Furthermore, in S6, the refining process is a three-stage refining process. Water glass is added as an inhibitor in the first and second refining processes, with a dosage of 100~300g / t.

[0025] Furthermore, the oxalic acid is added during or after the grinding process.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) This invention develops a special modifier combination for a specific difficult-to-process scheelite ore in Guangxi (the original ore has a WO3 grade of 0.56%, and the gangue is densely embedded and fine-grained). Oxalic acid is used as the modifier, and the carboxyl group in the oxalic acid molecule reacts with the Ca on the surface of calcium-containing gangue minerals such as calcite. 2+ Selective chelation occurs, forming a hydrophilic film on the surface of gangue minerals, thereby selectively inhibiting calcium-containing gangue minerals. This solves the technical problem that conventional sodium carbonate modifiers are basically ineffective and cannot achieve effective separation of this type of difficult-to-process scheelite.

[0028] (2) The present invention uses oxalic acid as a modifier. Through the cleaning effect of oxalic acid on the surface of scheelite, the contamination of the surface of scheelite by the residual reagents of the front-end sulfide mineral flotation is effectively eliminated, providing a clean reaction interface for the effective adsorption of the subsequent GY chelating collector on the surface of scheelite, and solving the problem that the collector is difficult to adsorb due to the residual reagent covering the surface of scheelite.

[0029] (3) The present invention adopts a synergistic reagent combination of oxalic acid and GY chelating collector. By utilizing the division of labor and synergistic mechanism of oxalic acid selectively inhibiting calcium-containing gangue and GY collector selectively collecting scheelite, the target mineral and gangue mineral are efficiently separated, which solves the problems of insufficient selectivity and low separation efficiency of single reagent system.

[0030] (4) The present invention adopts a flotation process structure of one roughing, one scavenging and three cleaning, and with the sequential return of ore in each operation, it realizes the full recovery of useful components and the gradual improvement of concentrate grade, and obtains high-grade final concentrate while ensuring recovery rate.

[0031] (5) This invention targets spruce ore with a WO3 grade of only 0.56%, dense gangue embedding, and fine particle size. Under mild conditions without heating or using toxic agents, spruce concentrate with a WO3 grade of 23.20% and a recovery rate of 54.70% can be obtained, solving the technical problem of economically and effectively recovering low-grade, fine-grained, difficult-to-process spruce ore. Attached Figure Description

[0032] Figure 1 This is a flow chart of the flotation process for difficult-to-process scheelite in Embodiment 1 of the present invention. Detailed Implementation

[0033] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0034] Unless otherwise specified, all raw materials or reagents used in the following examples are commercially available products.

[0035] In this embodiment, the GY chelating collector was purchased from the Guangzhou Nonferrous Metals Research Institute, the No. 2 oil was an industrial-grade frother, and the remaining reagents were of analytical grade. The flotation equipment used was an XFD series flotation machine, with the flotation cell volume adapted to the pulp volume.

[0036] The raw ore was a scheelite mine in Guangxi. The results of the multi-element chemical analysis of the raw ore are shown in Table 1.

[0037] Table 1. Results of multi-element chemical analysis of the raw ore

[0038]

[0039] The main metallic minerals are magnetite and pyrite, followed by a small amount of lead ore; the non-metallic minerals are mainly apatite, dolomite, mica, calcite, and talc. Scheelite has a fine grain size and is closely related to gangue minerals, making it a difficult-to-process ore.

[0040] Example 1

[0041] The flotation modifier combination used in this embodiment for refractory scheelite is: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0042] A flotation process for refractory scheelite, comprising the following steps:

[0043] S1: Grinding: Take 500g of the above raw ore and grind it in an XMQ-240×90 conical ball mill until -0.074mm accounts for 75%;

[0044] S2: Slurry preparation and reagent addition: Transfer the ground slurry into the XFD-1.5L flotation cell and add reagents in the following order:

[0045] Add 200g / t of oxalic acid, stir for 3 minutes, and adjust the pH of the slurry to 7.0;

[0046] Add 800g / t of lead nitrate and stir for 3 minutes;

[0047] Add 400g / t of GY chelating collector and stir for 3 minutes;

[0048] Add 40g of No. 2 oil and stir for 1 minute;

[0049] S3: Roughing: Aerated flotation, skimming time 5 min, to obtain roughing concentrate and roughing tailings;

[0050] S4: Scavenging: Scavenging is performed on the roughing tailings. During the scavenging operation, 100g / t of GY collector is added, and the aeration and scraping are carried out for 3 minutes. The scavenging concentrate is returned to the roughing operation, and the scavenging tailings are the final tailings.

[0051] S5: Fine Concentration: The rougher concentrate is fined three times. In the first fine concentration, 200g / t of water glass is added, stirred for 2 minutes, and then aerated and skimmed for 3 minutes. The middlings 1 are returned to the rougher operation. In the second fine concentration, 200g / t of water glass is added, stirred for 2 minutes, and then aerated and skimmed for 3 minutes. The middlings 2 are returned to the first fine concentration. In the third fine concentration, no reagents are added, and the middlings 3 are aerated and skimmed for 2 minutes. The middlings 3 are returned to the second fine concentration. The product in the tank is the final scheelite concentrate.

[0052] The results of the flotation tests are shown in Table 2 below;

[0053] Table 2 Results of flotation test in Example 1

[0054]

[0055] As shown in Table 2, using the modifier combination and flotation process of this embodiment, the WO3 grade of the raw ore is 0.58%. After one roughing, one scavenging and three cleaning flotation processes, a tungsten concentrate with a WO3 grade of 23.20% and a recovery rate of 54.70% can be obtained. The concentrate grade is nearly 40 times richer than that of the raw ore, and the separation effect is significant.

[0056] Example 2

[0057] The flotation modifier combination used in this embodiment for refractory scheelite is: 100g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0058] A flotation process for refractory scheelite is the same as in Example 1; namely: grinding to -0.074mm (75%) → sequentially adding oxalic acid (100g / t), lead nitrate, GY collector, and No. 2 oil → one roughing, one scavenging, and three cleaning flotation processes, with 100g / t of GY collector added during scavenging, and 200g / t of water glass added during the first and second cleaning processes.

[0059] The results of the flotation tests are shown in Table 3 below;

[0060] Table 3 Results of flotation test in Example 2

[0061]

[0062] As shown in Table 3, when the dosage of oxalic acid is 100 g / t, the inhibitory effect on calcium-containing gangue is insufficient, and the concentrate grade is only 12.35%, which is significantly lower than that in Example 1.

[0063] Example 3

[0064] The modifier combination in this embodiment is: 300g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0065] The flotation process steps are exactly the same as in Example 1.

[0066] The results of the flotation tests are shown in Table 4 below;

[0067] Table 4. Results of flotation test in Example 3

[0068]

[0069] As shown in Table 4, when the oxalic acid dosage is 300 g / t, although the concentrate grade is further increased to 28.15%, the recovery rate drops significantly to 40.37%, indicating that excessive oxalic acid also has a certain degree of inhibitory effect on scheelite.

[0070] Example 4

[0071] The modifier combination in this embodiment is: 150g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0072] The flotation process steps are exactly the same as in Example 1.

[0073] The results of the flotation tests are shown in Table 5 below;

[0074] Table 5 Results of flotation test in Example 4

[0075]

[0076] As shown in Table 5, when the oxalic acid concentration is 150 g / t, the concentrate grade is 18.76% and the recovery rate is 53.45%. The indicators are significantly improved compared with Example 2 (oxalic acid 100 g / t), but are still slightly inferior to Example 1 (oxalic acid 200 g / t).

[0077] Example 5

[0078] The modifier combination in this embodiment is: 250g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0079] The flotation process steps are exactly the same as in Example 1.

[0080] The results of the flotation tests are shown in Table 6 below;

[0081] Table 6 Results of flotation test in Example 5

[0082]

[0083] As shown in Table 6, when the oxalic acid content is 250 g / t, the concentrate grade is 26.83%, which is higher than that in Example 1, but the recovery rate drops to 48.26%, indicating that the recovery rate begins to decline after the oxalic acid content exceeds 200 g / t.

[0084] Example 6

[0085] The modifier combination in this embodiment is: 200g / t oxalic acid + 800g / t lead nitrate + 300g / t GY chelating collector + 40g / t No. 2 oil.

[0086] The flotation process steps are exactly the same as in Example 1.

[0087] The results of the flotation tests are shown in Table 7 below;

[0088] Table 7 Results of flotation test in Example 6

[0089]

[0090] As shown in Table 7, when the GY collector dosage is 300 g / t, the recovery rate is significantly low (only 36.25%), indicating that the collector dosage is insufficient and the scheelite is not fully recovered.

[0091] Example 7

[0092] The modifier combination in this embodiment is: 200g / t oxalic acid + 800g / t lead nitrate + 500g / t GY chelating collector + 40g / t No. 2 oil.

[0093] The flotation process steps are exactly the same as in Example 1.

[0094] The results of the flotation tests are shown in Table 8 below;

[0095] Table 8 Results of flotation test in Example 7

[0096]

[0097] As shown in Table 8, when the GY collector was increased to 500 g / t, the recovery rate increased to 56.32%, but the concentrate grade decreased to 20.85%, indicating that excessive collector will reduce selectivity.

[0098] Example 8

[0099] The roughing agent combination is: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil. For scavenging operations, an additional 50g / t of GY collector is added.

[0100] The flotation process steps are the same as in Example 1, except that 50 g / t of GY collector is added during the scavenging operation.

[0101] The results of the flotation tests are shown in Table 9 below;

[0102] Table 9 Results of flotation test in Example 8

[0103]

[0104] As shown in Table 9, when the amount of scavenging collector added was reduced to 50 g / t, the recovery rate decreased compared to Example 1 (52.18% vs 54.70%), indicating that the amount of scavenging collector should be 100 g / t.

[0105] Example 9

[0106] The roughing agent combination is: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil. For scavenging operations, 150g / t of GY collector is added.

[0107] The only difference between the flotation process steps and those in Example 1 is the addition of 150 g / t of GY collector during the scavenging operation.

[0108] The flotation test results are shown in Table 10 below;

[0109] Table 10 Results of flotation test in Example 9

[0110]

[0111] As shown in Table 10, when the amount of GY collector added to the scavenging process increased to 150 g / t, the recovery rate slightly increased to 55.36%, but the concentrate grade decreased to 22.15%, and the overall performance was not as good as in Example 1.

[0112] Example 10

[0113] The modifier combination is the same as in Example 1: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0114] The flotation process steps are basically the same as in Example 1, except that the stirring time after adding oxalic acid is shortened from 3 minutes to 1 minute, that is, the reaction time between oxalic acid and slurry is 1 minute.

[0115] The results of the flotation tests are shown in Table 11 below;

[0116] Table 11 Results of flotation test in Example 10

[0117]

[0118] As shown in Table 11, when the reaction time of oxalic acid is too short (1 min), the modifier fails to fully react with the mineral surface, and the concentrate grade is only 10.32%, which is a poor effect.

[0119] Example 11

[0120] The modifier combination is the same as in Example 1: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0121] The flotation process steps are basically the same as in Example 1, except that the stirring time after adding oxalic acid is extended from 3 minutes to 5 minutes.

[0122] The results of the flotation tests are shown in Table 12 below;

[0123] Table 12 Results of flotation test in Example 11

[0124]

[0125] As shown in Table 12, when the reaction time of oxalic acid was extended to 5 min, the concentrate grade increased slightly (23.56%), but the recovery rate decreased compared with Example 1 (52.38% vs 54.70%), indicating that the optimal reaction time of oxalic acid is 3 min.

[0126] Example 12

[0127] The modifier combination is the same as in Example 1: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0128] The flotation process steps are basically the same as in Example 1, except that the stirring time after adding oxalic acid is extended to 10 minutes.

[0129] The results of the flotation tests are shown in Table 13 below;

[0130] Table 13 Results of flotation test in Example 12

[0131]

[0132] As shown in Tables 12 and 13, the recovery rate continued to decrease after the oxalic acid reaction time exceeded 5 min (it dropped to 48.65% at 10 min), indicating that excessive oxalic acid reaction would have an adverse effect on scheelite.

[0133] Comparative Example 1

[0134] The modifier combination is: 2000g / t sodium carbonate + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0135] The flotation process steps are basically the same as in Example 1, except that: 2000g / t of sodium carbonate is added to replace oxalic acid, stirred for 3 minutes, and the pH of the pulp is adjusted to 9.0; the order of addition of other reagents and the flotation process are completely consistent with those in Example 1.

[0136] The experimental results are shown in Table 14;

[0137] Table 14. Flotation test results of Comparative Example 1 (sodium carbonate as modifier)

[0138]

[0139] As shown in Table 14, when sodium carbonate is used as a modifier, there is almost no difference in WO3 grade among the products. The WO3 grade of tungsten concentrate is only 0.68%, and the recovery rate is only 6.38%, indicating that sodium carbonate is basically ineffective for this ore and cannot achieve effective separation. This shows that oxalic acid, as a modifier in this invention, plays an irreplaceable and crucial role for this difficult-to-process ore.

[0140] Comparative Example 2

[0141] The modifier combination is: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t 731 collector + 40g / t 2# oil.

[0142] The flotation process steps are the same as in Example 1.

[0143] The experimental results are shown in Table 15;

[0144] Table 15 Results of flotation tests in Comparative Example 2 (731 collector)

[0145]

[0146] As shown in Table 15, even with oxalic acid as a modifier, the flotation effect of collector 731 was still extremely poor, with a WO3 grade of only 1.85% and a recovery rate of only 20.36%. Compared with Example 1, the concentrate grade differed by more than 10 times, and the recovery rate differed by nearly 2.7 times, indicating that the combination of oxalic acid and GY collector in this invention has a specific synergistic effect, and not any combination of collector and oxalic acid can achieve good results.

[0147] Comparative Example 3

[0148] This comparative example does not add any modifiers, only the following: 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0149] The flotation process steps are basically the same as in Example 1, except that the oxalic acid addition step is omitted. That is, lead nitrate, GY collector and No. 2 oil are added directly after grinding. The subsequent scavenging and cleaning processes are the same as in Example 1.

[0150] The experimental results are shown in Table 16;

[0151] Table 16. Flotation test results of Comparative Example 3 (without modifier)

[0152]

[0153] As shown in Table 16, even with the use of GY collector, the flotation separation effect is still extremely poor without the addition of oxalic acid as a modifier, with the WO3 grade of the concentrate being only 0.92%. This indicates that oxalic acid plays an irreplaceable key role in this process system. The inhibitory effect of oxalic acid on calcium-bearing gangue and its function of cleaning the surface of scheelite are prerequisites for GY collector to exert its selective collecting effect.

[0154] Comparative Example 4

[0155] The modifier combination for this comparative example is: 2000g / t water glass + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0156] The flotation process steps are basically the same as in Example 1, except that 2000g / t of water glass is added to replace oxalic acid, while the other reagents and flotation process are the same as in Example 1.

[0157] The experimental results are shown in Table 17;

[0158] Table 17 Results of flotation test in Comparative Example 4 (using water glass as a modifier)

[0159]

[0160] As shown in Table 17, when conventional water glass was used as a modifier, the WO3 grade of the concentrate was only 1.52%, and the recovery rate was only 11.82%. Although the separation effect was slightly better than that of sodium carbonate (Comparative Example 1), it was still far inferior to the oxalic acid scheme of this invention (Example 1). This indicates that for this densely embedded, high-calcium gangue-containing, difficult-to-process ore, oxalic acid has a specific inhibitory effect that cannot be replaced by other conventional modifiers.

[0161] Comparative Example 5

[0162] The modifier combination for this comparative example is: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t benzohydroxyxamic acid + 40g / t No. 2 oil.

[0163] The flotation process steps are exactly the same as in Example 1.

[0164] The experimental results are shown in Table 18;

[0165] Table 18 Results of flotation test in Comparative Example 5 (using water glass as a modifier)

[0166]

[0167] As shown in Table 18, when benzohydroxyxamic acid is used as a collector, the concentrate grade is only 8.56%, which is significantly lower than that of GY collector (Example 1, 23.20%), indicating that GY collector has better selective collection performance in the reagent system of the present invention.

[0168] Comparative Example 6

[0169] The modifier combination for this comparative example is: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t salicylic acid + 40g / t No. 2 oil.

[0170] The flotation process steps are exactly the same as in Example 1.

[0171] The experimental results are shown in Table 19;

[0172] Table 19. Results of flotation tests in Comparative Example 6 (using salicylic acid as a collector).

[0173]

[0174] As shown in Table 19, when salicylic acid is used as a collector, the concentrate grade is only 6.32% and the recovery rate is only 29.15%, which is the worst effect, further illustrating the specific advantages of GY collector in the system of this invention.

[0175] Comparative Example 7

[0176] The modifier combination for this comparative example is: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t sodium oleate + 40g / t No. 2 oil.

[0177] The flotation process steps are exactly the same as in Example 1.

[0178] The experimental results are shown in Table 20;

[0179] Table 20 Results of flotation test in Comparative Example 7 (sodium oleate as collector)

[0180]

[0181] As shown in Table 20, when sodium oleate is used as a collector, the concentrate grade is only 3.21% and the recovery rate is only 21.68%, which is far less effective than that of GY collector.

[0182] Comparative Example 8

[0183] The modifier combination is the same as in Example 1: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0184] The difference between the flotation process steps and those in Example 1 is that the cleaning operation only involves two cleaning processes (i.e., one roughing, one scavenging, and two cleaning), and the middlings return method is adjusted accordingly.

[0185] The experimental results are shown in Table 21;

[0186] Table 21 Results of flotation tests in Comparative Example 8 (two rounds of fine selection)

[0187]

[0188] As shown in Table 21, after reducing the number of cleaning stages, the concentrate grade dropped significantly to 12.86%. Although the recovery rate increased slightly (56.38%), the concentrate grade could not meet the quality requirements of qualified concentrate, indicating that the three cleaning stages play an important role in ensuring the concentrate grade.

[0189] Comparative Example 9

[0190] The modifier combination is the same as in Example 1: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

[0191] The flotation process adopts a roughing, scavenging and refining process, and the operation of adding water glass in each refining step is the same as in Example 1.

[0192] The experimental results are shown in Table 22;

[0193] Table 22 Results of flotation tests in Comparative Example 9 (two rounds of fine selection)

[0194]

[0195] As shown in Table 22, when the number of beneficiation steps is increased to four, the concentrate grade increases to 25.68%, but the recovery rate drops significantly to 42.35%. The process is lengthy and the indicators are not good, indicating that three beneficiation steps are the optimal choice for this invention.

Claims

1. A flotation modifier for refractory scheelite, characterized in that, This includes oxalic acid as a modifier, lead nitrate as an activator, and GY chelating collector as a collector; The amount of oxalic acid used in the flotation roughing operation is 150~300g / t, the amount of lead nitrate is 600~1000g / t, and the amount of GY chelating collector is 300~500g / t.

2. The flotation modifier for refractory scheelite according to claim 1, characterized in that, The flotation modifier also includes a frother, which is No. 2 oil, and the dosage is 20~60g / t.

3. The flotation modifier for refractory scheelite according to claim 2, characterized in that, The flotation modifier is: 200g / t oxalic acid + 800g / t lead nitrate + 400g / t GY chelating collector + 40g / t No. 2 oil.

4. A flotation process for refractory scheelite using any one of the flotation modifiers described in claims 1 to 3, characterized in that, The steps are as follows: S1: Grind the refractory scheelite ore to -0.074mm, accounting for 65%~85%; S2: Add oxalic acid to the slurry as a modifier. The reaction time of oxalic acid with the slurry is 2-5 minutes, and adjust the pH of the slurry to 6.0-8.

0. S3: Add lead nitrate to the slurry as an activator; S4: Add GY chelating collector and No. 2 oil frother to the slurry for roughing operation; S5: Perform scavenging on the roughing tailings, and return the scavenged concentrate to the roughing operation; S6: Perform at least three fine-refinement operations on the rough concentrate, and return the middlings from each fine-refinement operation to the previous operation in sequence to finally obtain scheelite concentrate.

5. The flotation process for refractory scheelite according to claim 4, characterized in that, The refractory scheelite is a scheelite with a WO3 grade of 0.3%~1.0% and a calcite content of ≥15%.

6. The flotation process for refractory scheelite according to claim 5, characterized in that, The refractory scheelite is a scheelite ore with a WO3 grade of 0.5%~0.6% and a total content of calcite and dolomite in gangue minerals of ≥20%.

7. The flotation process for refractory scheelite according to claim 4, characterized in that, In S4, the amount of oxalic acid used in the roughing operation is 150-300 g / t, the amount of lead nitrate is 600-1000 g / t, the amount of GY chelating collector is 300-500 g / t, and the amount of No. 2 oil is 20-60 g / t.

8. The flotation process for refractory scheelite according to claim 4, characterized in that, In S5, the scavenging operation is a single scavenging operation, during which 50~150g / t of GY chelating collector is added.

9. The flotation process for refractory scheelite according to claim 4, characterized in that, In S6, the refining process consists of three refining operations. Water glass is added as an inhibitor in the first and second refining operations, with a dosage of 100~300g / t.

10. The flotation process for refractory scheelite according to claim 4, characterized in that, The oxalic acid is added during or after the grinding process.

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