Beneficiation method for recovering micro-fine particle cassiterite and fluorite from cassiterite tailings

Abstract

The invention discloses a beneficiation method for recovering micro-fine particle cassiterite and fluorite from cassiterite tailings, and belongs to the technical field of beneficiation. The method comprises the steps that cassiterite tailings are subjected to reselection, obtained reselected bulk concentrate is subjected to ore grinding and then sequentially subjected to magnetic separation iron removal and flotation desulfurization, and the desulfurized tailings are subjected to cassiterite flotation with metal ion modified water glass with the valence higher than bivalent as an inhibitor and a metal-based multi-ligand organic complex as a collecting agent, so that cassiterite concentrate and flotation tailings are obtained; and the flotation tailings and the gravity separation tailings are combined, water glass or acidified water glass serves as an inhibitor, aliphatic carboxylic acid and heavy alkyl benzene sulfonate serve as a composite collecting agent, fluorite flotation is conducted, and fluorite concentrate is obtained. According to the method, the technological process is simple, the ore grinding and agent cost can be remarkably reduced, and selective separation of cassiterite and fluorite is achieved while efficient recycling of micro-fine particle cassiterite is achieved.

Description

Technical Field

[0001] The invention relates to a method for processing cassiterite tailings, in particular to a beneficiation method for comprehensively recovering fine-grained cassiterite and fluorite from the cassiterite tailings, and belongs to the field of mineral processing technology utilization. Background Art

[0002] Cassiterite (SnO2) is the only tin-containing mineral with industrial mining value and the primary source of global tin resources. As a strategic metal, tin is widely used in key sectors such as electronics and information technology, chemical materials, metal alloys, and new energy. It is particularly irreplaceable in high-tech industries such as lead-free solder, lithium batteries, and solar cells.

[0003] Fluorite (CaF2) is a major fluorine-containing mineral and a core raw material for hydrofluoric acid and its downstream fluorine-based chemical products (such as fluoropolymers, refrigerants, pesticides, and pharmaceuticals). It plays a vital role in the chemical, electronics, and new materials sectors. Fluorite is also used as a flux in the metallurgical industry to improve steelmaking efficiency and metal purity. High-purity fluorite is also used in the manufacture of optical components and lasers, and is widely used in the aerospace and military sectors. With the development of high-tech industries, the strategic value and resource security significance of fluorite are becoming increasingly prominent.

[0004] Cassiterite tailings often contain large amounts of finely embedded cassiterite with complex associations with other minerals, making beneficiation difficult, low-grade, and difficult to economically recover. The associated fluorite resources are often stored in tailings ponds along with the gangue minerals, resulting in significant waste of resources and land occupation, as well as environmental risks. The secondary development and utilization of metal resources in tailings is crucial for the sustainable development of mines. The key to comprehensive recovery of low-grade cassiterite and fluorite resources lies in achieving monomeric dissociation of useful minerals, selective suppression of gangue minerals, and selective separation of cassiterite and fluorite, while ensuring recovery rates and reducing production costs. In the existing technology, the simultaneous recovery of low-grade cassiterite and fluorite resources often faces problems such as high grinding costs, large amounts of reagents used, and complex separation processes; the large amount of inhibitors added when preferentially flotating fluorite with better floatability will have an adverse effect on the subsequent separation of cassiterite, and fatty acid collectors will often entrain some cassiterite, affecting the comprehensive recovery of resources; because cassiterite is brittle and easily over-ground and muddied, traditional gravity separation and flotation methods have poor recovery effects on fine-grained cassiterite. When using flotation methods to recover cassiterite, they often face problems such as small processing capacity and high grinding and reagent costs.

[0005] In summary, developing an economically reasonable beneficiation method for the comprehensive recovery of low-grade fine-grained cassiterite and fluorite resources in cassiterite tailings will have important guiding significance for the efficient recycling and utilization of resources. Summary of the Invention

[0006] In view of the technical problems that useful minerals such as cassiterite and fluorite in cassiterite tailings are of low grade and fine embedded particle size, resulting in great difficulty and high cost in mineral processing, the purpose of the present invention is to provide a mineral processing method for the comprehensive recovery of low-grade fine-grained cassiterite and fluorite resources in cassiterite tailings. The method has a simple process flow, can significantly reduce the cost of grinding and reagents, and realizes the selective separation of cassiterite and fluorite while achieving efficient recovery of fine-grained cassiterite.

[0007] In order to achieve the above technical objectives, the present invention provides a beneficiation method for recovering fine particles of cassiterite and fluorite from cassiterite tailings, which comprises the following steps:

[0008] 1) After slurry adjustment, the cassiterite tailings are re-selected and classified using a spiral classifier. The returned sand from the classification is pre-selected in a spiral chute, and the overflow from the classification is pre-selected in a centrifugal concentrator. The pre-selected concentrate from the spiral chute and the pre-selected concentrate from the centrifugal concentrator are combined to obtain a mixed concentrate.

[0009] 2) After grinding, the mixed concentrate is subjected to magnetic separation for iron removal and flotation for desulfurization to obtain desulfurized tailings;

[0010] 3) After slurrying, the desulfurized tailings are subjected to cassiterite flotation using water glass modified with divalent or higher metal ions as an inhibitor and a metal-based multi-ligand organic complex as a collector to obtain cassiterite concentrate and flotation tailings;

[0011] The metal-based multi-ligand organic complex is assembled by coordination of divalent or higher-valent metal ions with hydroxamic acids and alkylbenzene sulfonates;

[0012] 4) After the flotation tailings are combined with the spiral chute pre-selection tailings and the centrifugal concentrator pre-selection tailings for slurry adjustment, fluorite flotation is carried out using water glass or acidified water glass as a depressant and fatty carboxylic acids and heavy alkylbenzene sulfonates as composite collectors to obtain fluorite concentrate.

[0013] The present invention provides a beneficiation method for recovering fine-grained cassiterite and fluorite from cassiterite tailings. According to the difference in the distribution rate of cassiterite minerals in various particle sizes, a spiral classifier is used to classify the cassiterite minerals to reduce the content of fine-grained cassiterite minerals in the coarse-grained return sand, thereby reducing the loss of fine-grained cassiterite minerals caused by insufficient equipment and processes during the coarse-grained separation process. The spiral classification return sand and overflow are discarded using a spiral chute and a centrifugal concentrator, respectively, to achieve preliminary enrichment of the cassiterite minerals. This can significantly reduce the grinding energy consumption and reagent costs of the subsequent cassiterite mineral flotation stage. The flotation of the cassiterite minerals uses a special metal-based multi-ligand collector, which has the characteristics of targeted adsorption and high selectivity on the surface of the cassiterite minerals. It uses metal ions as solid-affinity groups and can precisely act on the oxygen particles on the surface of cassiterite without reacting with the calcium particles on the surface of calcium-containing minerals such as fluorite. In particular, when used in combination with silicate polymers formed by modified water glass with divalent or higher metal ions, it can improve the flotation selectivity of metal-based multi-ligand collectors for cassiterite minerals, strengthen the separation of cassiterite minerals from gangue minerals, and simultaneously achieve efficient recovery of fine-grained cassiterite minerals and selective separation of cassiterite minerals from fluorite. Fluorite and gangue minerals enter the flotation tailings together, and after being combined with the gravity separation tailings, a composite collector composed of fatty carboxylic acids and heavy alkylbenzene sulfonates is used to strengthen the flotation of fluorite to obtain high-grade fluorite concentrate.

[0014] The mass content of gangue minerals such as quartz, muscovite, chlorite, feldspar, pyroxene, etc. in the cassiterite tailings of the present invention is greater than or equal to 60%, the mass content of SnO2 is greater than or equal to 0.12%, and the mass content of CaF2 is greater than or equal to 5.0%.

[0015] As a preferred solution, the cassiterite tailings are slurried to a concentration within the range of 25-35 wt.%.

[0016] As a preferred solution, the spiral classifier has an inclination angle of 15-25°. After the cassiterite tailings are classified by the spiral classifier at an appropriate inclination angle, coarser particle size return sand and finer particle size overflow are obtained.

[0017] As a preferred solution, the concentration of the ore pulp fed into the spiral chute is 25-30 wt.%, and the pitch of the spiral chute is controlled within the range of 40-60 mm.

[0018] As a preferred solution, the feed slurry concentration of the centrifugal concentrator is 20~25wt.%, the rotation speed of the centrifugal concentrator is 500~800 r / min, the centrifugal acceleration is 250~300G, the operating pressure is 100~120PSI, the feeding time is 40~80s, the interval time is 5~15s, the flushing time is 10~15s, and the reset time is 5~15s.

[0019] The present invention is based on the difference in distribution rate of cassiterite minerals in various particle sizes. The present invention reduces the content of fine-grained cassiterite minerals in coarse-grained return sand through classification by a spiral classifier, thereby reducing the loss of fine-grained cassiterite minerals caused by the coarse-grained separation process. By preliminarily classifying the cassiterite tailings and then performing gravity separation on them, not only can the loss of fine-grained cassiterite minerals be reduced, but also the preliminary enrichment of fine-grained cassiterite can be achieved. The SnO2 mass content of the spiral chute concentrate is ≥0.18%, the SnO2 mass content of the centrifugal concentrator concentrate is ≥0.35%, the SnO2 mass content of the mixed concentrate obtained by gravity separation is ≥0.25%, the recovery rate is ≥85%, and the SnO2 mass content of the combined gravity separation tailings is ≤0.05%.

[0020] As a preferred solution, the mixed concentrate is ground to a particle size of 80-85% by mass meeting the -0.074mm particle size. The mixed concentrate is wet-milled in an XMQ conical ball mill measuring 240mm x 90mm. The slurry concentration is controlled at 50-60wt.%, and the content of the -0.074mm particle size in the ground product is ≥80%, which facilitates further dissociation of the cassiterite minerals.

[0021] As a preferred solution, the magnetic separation and iron removal uses a drum-type wet weak magnetic separator, and the magnetic separation and iron removal process controls the pulp concentration to 40-50wt.%, and the magnetic field strength is 400-600KA / m. The drum-type wet weak magnetic separator is, for example, an XCRS-φ400×300 drum-type wet weak magnetic separator. The magnetic field strength is further preferably 500-600KA / m. Since metal-based multi-ligand collectors can selectively adsorb on the surface of iron oxides, thereby adversely affecting cassiterite flotation, the use of weak magnetic separation to recover iron oxides can not only improve the effectiveness of the collector, but also recover part of the magnetite, which is beneficial to the comprehensive utilization of resources.

[0022] As a preferred solution, the flotation desulfurization reagent system is as follows: the copper sulfate activator is used at a dosage of 100-200 g / t, the butyl xanthate collector is used at a dosage of 150-200 g / t, and the foaming agent pine oil is used at a dosage of 25-30 g / t. As a preferred solution, the reagent action time and flotation time are both 5 minutes.

[0023] As a preferred solution, the divalent or higher metal ion modified water glass is obtained by compounding divalent or higher metal ions and water glass in a molar ratio of 1: (1-5), wherein the divalent or higher metal ions include Fe 2+ , Pb 2+ 、Cu 2+ Mg 2+ 、Al 3 + The divalent or higher metal ion is further preferably Ca 2+ or Al3+ The divalent or higher metal ion-modified water glass is prepared by compounding the divalent or higher metal ions with water glass in a molar ratio of 1:(1-2). The silicate colloids generated by the chemical reaction between the water glass and the metal ions are larger than those of ordinary water glass, have more surface hydroxyl groups, are more active, and have stronger adsorption on silicate mineral surfaces. This allows for efficient inhibition of silicate minerals such as quartz with a relatively low dosage.

[0024] As a preferred solution, the metal-based multi-ligand organic complex is assembled by coordination of divalent or higher metal ions with hydroxamic acids and alkylbenzene sulfonates in a molar ratio of (1-20): (1-10): 1, wherein the divalent or higher metal ions include Ca 2+ Mg 2+ 、Zn 2+ 、Fe 2+ , Pb 2+ 、Cu 2+ 、Mn 2+ 、Fe 3+ or Al 3+ At least one of them. The metal organic complex is further preferably assembled by coordination of divalent or higher metal ions with hydroxamic acids and alkylbenzene sulfonates in a molar ratio of (1~5): (1~2): 1. The metal-based multi-ligand collector uses divalent or higher metal ions as polar groups, has a targeted adsorption effect on the oxygen active sites on the surface of cassiterite, and basically does not react with calcium particles on the surface of calcium-containing minerals such as fluorite. When used in conjunction with metal ion-modified water glass, it can effectively inhibit the coordination of organic functional groups such as hydroxamic acid groups and sulfonic acid groups in the multi-ligand with divalent or higher metal ions, which can enhance the adsorption capacity of the metal base and the hydrophobicity of the non-polar group, thereby enhancing the flotation recovery of fine-grained cassiterite. The divalent or higher metal ions are further preferably Pb 2+ 、Mn 2+ or Fe 3+ These metal-based multi-ligand organic complexes constructed with divalent or higher metal ions have better targeted adsorption effects on cassiterite.

[0025] As a preferred embodiment, the hydroxamic acid includes at least one of benzohydroxamic acid, salicylic hydroxamic acid, and C7-C9 alkyl hydroxamic acid.

[0026] As a preferred embodiment, the alkylbenzene sulfonates include C 10 ~C 14 At least one of the linear alkylbenzene sulfonates of alkylbenzene sulfonates such as potassium salt, sodium salt or ammonium salt.

[0027] As a preferred embodiment, the cassiterite flotation process includes one roughing operation and three to six concentrating operations. The roughing process includes a pH adjuster to adjust the pulp pH to a range of 10.0 to 12.0, a depressant dosage of 100 to 500 g / t, a collector dosage of 500 to 1000 g / t, and a frother dosage of 20 to 40 g / t. The pH adjuster is a compound alkali composed of NaOH and Na2CO3 in a mass ratio of (1 to 2):1. The concentrating process includes a depressant dosage that decreases in a stepwise manner. The pH adjuster is preferably a compound alkali composed of NaOH and Na2CO3 in a mass ratio of (1 to 2):1. The pH is further preferably adjusted to 10.0 to 10.5. The mixed alkali is further preferably composed of NaOH and Na2CO3 in a mass ratio of 1:1. Metal-based multi-ligand collectors are more sensitive to the pH conditions of the slurry. Therefore, Na2CO3 is used as a buffer to maintain the stability of the slurry pH. It can also be used as a dispersant to promote the separation of cassiterite and surface slime. At the same time, the alkaline slurry environment adjusted by NaOH is conducive to promoting the participation of some hydroxides in the coordination assembly of the collector, which is beneficial to improving the selectivity and capture capacity of the collector.

[0028] In the cassiterite flotation process of the present invention, the reagent types and reagent system are optimized to obtain a cassiterite concentrate with a SnO2 mass content of ≥8.0%, a recovery rate of not less than 50.0%, and a fluorite recovery rate in the tailings of not less than 90.0%, thereby achieving efficient enrichment of fine-grained cassiterite. At the same time, most of the fluorite enters the tailings, achieving efficient separation of fine-grained cassiterite and fluorite.

[0029] As a preferred embodiment, the fatty acids include at least one of oleic acid, linoleic acid, tall oil, lauric acid, linolenic acid, palmitic acid, stearic acid, erucic acid, and oxidized paraffin soap.

[0030] As a preferred solution, the relative molecular mass of the heavy alkylbenzene sulfonate is 300-800.

[0031] As a preferred solution, the composite collector is composed of fatty acids and heavy alkylbenzene sulfonates in a mass ratio of (1-5):1. The carboxyl group (-COOH) of the fatty acid in the composite collector reacts with the Ca 2+ The particles undergo chemical adsorption to form a hydrophobic layer, and the rigid benzene ring of HABS can be inserted into the gap between fatty acid molecules, and the sulfonic acid group (-SO3 -) can adsorb onto defect sites or weakly electropositive regions on the fluorite surface, and their long-chain alkylbenzene structure assists adsorption through hydrophobic association. Fatty acids and HABS form a denser mixed adsorption layer on the fluorite surface, reducing intermolecular repulsion and enhancing the stability of the hydrophobic film. Fatty acids also tend to form micelles in solution, lowering their effective concentration. As strong surfactants, HABS can lower the critical micelle concentration of collector adsorption at the solid / liquid interface in mixed systems, allowing more collector molecules to exist as monomers and improving adsorption efficiency. The combination of fatty acids and heavy alkylbenzene sulfonates combines both capture capacity and selectivity. Through their efficient synergistic effect, they can enhance the recovery of coarser-sized fluorite and undissociated fluorite conglomerates, ensuring the recovery rate of roughing.

[0032] As a preferred solution, the fluorite flotation process includes one roughing operation, four to ten cleaning operations, and one to two scavenging operations. The roughing concentrate is then regrinded. The roughing agent system includes a pH adjuster to adjust the pulp pH to 9.5-10.0, a water glass inhibitor dosage of 1000-3000 g / t, and a composite collector dosage of 100-300 g / t. The scavenging agent system includes a composite collector dosage halved, and the scavenging process returns to the previous operation. The cleaning agent system includes a composite collector dosage of 50-100 g / t for the first cleaning operation, an acidified water glass inhibitor dosage of 600-1000 g / t, and depressants for other cleaning operations decreasing in a step-by-step manner. The pH adjuster is sodium carbonate, which is used to adjust the pulp pH to 9.5-10.0. This pH condition is more conducive to fluorite flotation. The amount of water glass inhibitor used in the roughing process is further preferably 2000-2500 g / t. The amount of acidified water glass inhibitor used in the fine selection process is further preferably 600-800 g / t. By optimizing the reagent type and reagent system during fluorite flotation, a fluorite roughing concentrate with a CaF2 mass content of ≥40% and a recovery rate of not less than 90% can be obtained; a fluorite final concentrate with a CaF2 mass content of ≥85% and a recovery rate of not less than 50%. The acidified water glass inhibitor of the present invention is a conventional inhibitor for fluorite fine selection in the prior art, and is formed by compounding sulfuric acid and water glass in a mass ratio of 1:(1-2). Compared with single water glass, acidified water glass has a stronger silicon reduction effect, and also has a selective inhibitory effect on calcium-containing minerals such as calcite. At the same time, it can improve the flotation foam state, strengthen the secondary enrichment effect, and improve the efficiency of fluorite flotation.

[0033] As a preferred solution, the regrinding process controls the particle size to achieve a mass fraction of ≥85% within the -0.074mm fraction. The rougher concentrate is wet-milled in an XMQ conical ball mill with dimensions of 240mm x 90mm. The ground product has a mass fraction of ≥85% within the -0.074mm fraction. Regrinding the rougher concentrate further separates the fluorite from the gangue minerals, facilitating subsequent fluorite recovery.

[0034] Compared with the existing technology, the technical solution of the present invention brings the following beneficial technical effects:

[0035] 1. The technical solution of the present invention uses gravity separation to pre-enrich cassiterite. In particular, after the cassiterite tailings are classified by a spiral classifier, the returned sand obtained by classification is pre-discarded by a spiral chute, and the overflow is pre-discarded by a centrifuge. This not only reduces the loss of fine-grained cassiterite, but also effectively improves the pre-enrichment of fine-grained cassiterite, greatly reduces the processing volume of the subsequent cassiterite flotation stage, and is conducive to reducing the cost of grinding and reagents.

[0036] 2. The technical solution of the present invention uses a metal-based multi-ligand collector in the cassiterite flotation process, which can selectively act on the oxygen sites on the surface of cassiterite and has almost no binding effect on the surface of fluorite. When used simultaneously with a polymer obtained by modifying water glass with divalent or higher metal ions, it has synergistic selectivity, can enhance the separation from gangue minerals, and at the same time achieve efficient recovery of fine-grained cassiterite and selective separation of cassiterite and fluorite. Fluorite and gangue minerals enter the flotation tailings together, and only a small amount of inhibitor is added in the rough selection of cassiterite, which will not have an adverse effect on the flotation of fluorite.

[0037] 3. In the fluorite flotation process, the technical solution of the present invention differs from the conventional use of fatty acid collectors for fluorite flotation. Instead, a composite collector composed of fatty acids and heavy alkylbenzene sulfonates (HABS) is used for fluorite flotation. The combination of fatty acids and heavy alkylbenzene sulfonates has both capture ability and selectivity. Through the efficient synergistic effect of the two, the recovery of coarser-sized fluorite and undissociated fluorite intergrowths can be enhanced, thereby ensuring the recovery rate of roughing. At the same time, only the coarse concentrate needs to be regrinded in the fluorite flotation stage, which greatly reduces the grinding cost.

[0038] In summary, the technical solution of the present invention has the characteristics of low cost, short process, simple operation and strong adaptability. It realizes the effective comprehensive recovery of low-grade cassiterite and fluorite resources in cassiterite gravity separation tailings, which is conducive to large-scale promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a flow chart of the fluorite removal and tin selection process of Comparative Example 1.

[0040] Figure 2This is a process flow chart of Example 1, Example 2, Comparative Example 2, and Comparative Example 3. DETAILED DESCRIPTION

[0041] The following examples are provided to further illustrate the present invention in detail, but are not intended to limit the scope of protection of the claims of the present invention.

[0042] The acidified water glass inhibitor in the following examples and comparative examples was prepared as follows: a sulfuric acid solution and a water glass solution, both having a concentration of 10%, were uniformly mixed at a mass ratio of 1:2 under stirring to obtain the acidified water glass inhibitor.

[0043] The preparation of the mixed alkali in the following examples and comparative examples is as follows:

[0044] 10 g of sodium carbonate and 5 g of sodium hydroxide were weighed separately and placed in a beaker, water was added until the total weight of the solution was 100 g, and the mixture was thoroughly mixed under stirring to obtain the mixed alkaline solution.

[0045] The preparation of the composite collector of fluorite in the following specific examples and comparative examples is as follows:

[0046] Under stirring conditions, 0.5L of 1.0mol / L sodium oleate solution and 0.5L of 0.2mol / L heavy alkylbenzene sodium sulfonate solution were mixed evenly to obtain the composite collector for fluorite flotation.

[0047] The metal-based multi-ligand collectors in the following examples and comparative examples were prepared as follows: 0.125 mol of lead nitrate was added to 0.5 L of a 1.0 mol / L benzohydroxamic acid solution and 0.5 L of a 0.1 mol / L sodium dodecylbenzenesulfonate solution mixed under stirring, and the mixture was reacted for 3 minutes to obtain a metal-based multi-ligand collector.

[0048] Comparative Example 1 (Compared with Example 1)

[0049] In a tin-bearing tailings sample from Jiangxi Province, the ore had a fineness of -0.074mm and a content of 55%. The sample contained 0.15% SnO2 and 6.09% CaF2. The main minerals in the ore included quartz, fluorite, mica, feldspar, amphibole, chlorite, and pyroxene. Quartz accounted for approximately 75%, while other minerals, such as mica, feldspar, amphibole, chlorite, and pyroxene, accounted for approximately 20%.

[0050] Use Figure 1The fluorite removal and tin selection process shown in the figure is to prepare the cassiterite tailings into a 50wt% slurry, and after wet ball mill grinding, a grinding product with a -0.074mm content greater than 80% is obtained. The grinding product is iron-removed using an XCRS-φ400×300 drum-shaped wet weak magnetic separator, and the magnetic field strength is set to 500KA / m. The magnetic tailings are subjected to desulfurization flotation, and the amount of copper sulfate activator, butyl xanthate collector and pine oil foaming agent is 200g / t. Water glass is added to the desulfurization tailings as a gangue mineral inhibitor in an amount of 2500g / t, and oil is added. Sodium oleate collector 500g / t, aerated slurry stirring for 5 minutes, then fluorite roughing operation was carried out. During the roughing process, the pulp pH was stable at about 10.2. This pH range is more conducive to fluorite floating; sodium oleate collector 250g / t was added during the scavenging operation; water glass was used as a depressant in the first two selections, and the dosage followed the principle of step-by-step reduction, which was 600g / t and 300g / t respectively; acidified water glass was used as a depressant in further selection, and the dosage was 300g / t and 150g / t respectively. After four selection operations, fluorite concentrate with a CaF2 grade of 83.56% was obtained, and the recovery rate was 68.65%. The fluorite tailings were removed by adjusting the pulp pH to a weak alkaline condition of about 9.7 with sodium carbonate, and Al 3+ Al-SBL obtained from modified water glass was used as an inhibitor, wherein the molar ratio of aluminum sulfate to water glass was 1:2, and the dosage was 300 g / t. Pb-BHA metal-based complex collector was used for cassiterite flotation, wherein the molar ratio of lead nitrate to benzohydroxamic acid was 1:2, and the dosage was 800 g / t. Pine oil was used as a frother, and the dosage was 30 g / t. The scavenging operation was halved relative to the roughing collector. The dosage of the fine selection inhibitor followed the principle of gradual decrease, namely 600 g / t, 300 g / t, and 150 g / t Al-SBL. After three rounds of concentration, a cassiterite concentrate with a SnO2 grade of 4.52% was obtained.

[0051]

[0052] As can be seen from Table 1, although the fluorite removal-tin selection process can obtain good fluorite selection indicators and produce fluorite concentrate with a CaF2 grade of 83.56% and a recovery rate of 68.65%, the comprehensive recovery effect of cassiterite is very poor, with a cassiterite recovery rate of less than 30%. A large amount of SnO2 is adsorbed by the fluorite collector and enriched in the fluorite concentrate, and is not effectively recovered, resulting in a serious waste of resources.

[0053] Comparative Example 2 (Compared with Example 1)

[0054] This example uses the desulfurized tailings of Example 1 for cassiterite flotation. The pH of the desulfurized tailings is adjusted to 10.0-12.0 using a mixed alkaline solution. The cassiterite flotation uses a water glass inhibitor dosage of 2000 g / t, a benzohydroxamic acid collector dosage of 800 g / t, and a pine oil frother dosage of 30 g / t. The concentration reagent system is to reduce the inhibitor dosage by half with each concentration step; the dosages are 200 g / t, 100 g / t, and 50 g / t, respectively. The selected middlings are returned to the previous operation in sequence. As can be seen from Table 2, the grade of the cassiterite concentrate is 3.88%, and the recovery rate is 52.82%. Although this method achieves a certain degree of cassiterite enrichment, the capture capacity and selectivity for low-grade fine cassiterite need to be improved. In addition, a large amount of water glass is added to the cassiterite coarse selection stage to inhibit gangue minerals, which is not conducive to the recovery of fluorite in the cassiterite tailings.

[0055]

[0056] Comparative Example 3 (Compared with Example 2)

[0057] In this example, the gravity separation tailings and cassiterite flotation tailings of Example 2 were combined and then fluorite was flotated. The mixed tailings were adjusted to a slurry concentration of about 40wt%, and the pH was adjusted to 9.5-10.0 using sodium carbonate. 1500g / t of water glass inhibitor and 250g / t of sodium oleate collector were used for fluorite roughing. The amount of scavenging collector was 80g / t. The roughing concentrate was wet-milled in an XMQ conical ball mill. The grinding product entered the concentration. The concentration reagent system was as follows: the amount of sodium oleate collector was 50g / t, and the amount of acidified water glass inhibitor was halved with the number of concentrations, which were 600g / t, 300g / t, 150g / t, and 75g / t, respectively. The middlings from the concentration and scavenging were returned to the previous operation in sequence to finally obtain fluorite concentrate. As can be seen from Table 3, although a high-grade fluorite concentrate can be obtained by using a single collector, its ability to collect coarse-grained fluorite and undissociated fluorite intergrowths is obviously insufficient, resulting in a CaF2 recovery rate in the tailings as high as 39.13%, and some fluorite resources are not effectively recovered.

[0058]

[0059] Example 1

[0060] The process of the present invention is used to treat a cassiterite tailing in Jiangxi Province. The slurry concentration is adjusted to about 25wt%, and a spiral classifier is used to classify the tailings at an inclination of 21°. The return sand under the condition of 21° of the spiral classifier is matched to obtain a slurry with a mass concentration of 25%, which is fed into a mixing barrel and fed into a spiral chute with a pitch of 40mm for testing. The overflow obtained by the spiral classifier under the condition of an inclination of 21° is subjected to centrifugal separation with a feed concentration of 20wt.%, a speed of 600r / min, a centrifugal acceleration of 300G, an operating pressure of 100PSI, a feed time of 60s, an interval of 10s, a flushing time of 10s, a reset time of 10s, and a rinse water volume of 3.3L / min. The reselection results are shown in Table 2. The re-selected concentrates were combined and wet-milled in an XMQ conical ball mill. The pulp concentration was controlled at 50wt%. The milled products were magnetically separated and iron removed using an XCRS-φ400×300 drum-shaped wet weak magnetic separator. The magnetic field strength was set at 500KA / m. The magnetic tailings were subjected to desulfurization flotation. The dosage of copper sulfate activator, butyl xanthate collector, and pine oil frother was 200g / t. The agent action time and flotation time were both 5min. ; The pH of the desulfurized tailings is adjusted to about 11 using mixed alkali; the dosage of Al-SBL inhibitor used in cassiterite flotation is 300g / t, among which the molar ratio of aluminum sulfate to water glass is 1:2, the dosage of metal-based multi-ligand collector is 800g / t, and the dosage of pine oil foaming agent is 30g / t; the selection reagent system is that the dosage of inhibitor is gradually halved with the number of selection times; respectively, 200g / t, 100g / t, and 50g / t, and the selected middlings are returned to the previous operation in sequence. After the gravity separation tailings and cassiterite flotation tailings are combined, the slurry concentration is adjusted to about 40wt%, and the pH is adjusted to about 9.7 using sodium carbonate. The fluorite roughing uses 2000g / t of water glass inhibitor and 200g / t of composite collector. The amount of composite collector for scavenging is 50g / t. The roughing concentrate is wet-milled in an XMQ conical ball mill, and the grinding product enters the concentrating process. The concentrating reagent system is as follows: the amount of composite collector for the first concentrating is 50g / t, and the amount of acidified water glass inhibitor is halved with the number of concentrating times, which is 800g / t, 400g / t, 200g / t, and 100g / t, respectively. The middlings from the concentrating and scavenging are returned to the previous operation in sequence, and finally cassiterite and fluorite concentrates are obtained.

[0061] As can be seen from Tables 4 and 5, the new method for treating cassiterite tailings can not only ensure the effective recovery of fluorite and cassiterite, but also the recovery effect of fluorite and cassiterite concentrates produced by the new method is better. The CaF2 grade of fluorite concentrate is 87.01% and the recovery rate is 66.19%, and the SnO2 grade of cassiterite concentrate is 9.23% and the recovery rate is 62.41%. The grade and recovery rate of the concentrate products have been improved to a certain extent.

[0062]

[0063]

[0064] Example 2

[0065] The low-grade, fine-grained tin-bearing tailings from a certain place in Hunan used in this example have a cassiterite grade of about 0.32% and a fluorite grade of about 8.75%. The main gangue minerals are quartz, mica, garnet, tourmaline, etc., among which the quartz content is about 50%, the garnet content is about 25%, and the content of other minerals is relatively small.

[0066] The process of the present invention was used to treat a cassiterite tailing in Hunan Province. The slurry concentration was adjusted to about 25wt%, and a spiral classifier was used to classify the tailings at an inclination of 21°. The return sand under the spiral classifier at 21° was mixed to obtain a slurry with a mass concentration of 25%, which was fed into a mixing barrel and fed into a spiral chute with a pitch of 40mm for testing. The overflow obtained by the spiral classifier at an inclination of 21° was subjected to centrifugal separation under the conditions of a feed concentration of 20wt.%, a rotation speed of 600r / min, a centrifugal acceleration of 300G, an operating pressure of 100PSI, a feed time of 70s, an interval time of 8s, a flushing time of 13s, a reset time of 10s, and a rinsing water volume of 3.0L / min. The re-selected concentrates were combined and wet-milled in an XMQ conical ball mill. The pulp concentration was controlled at 50wt%. The milled products were magnetically separated and iron removed using an XCRS-φ400×300 drum-shaped wet weak magnetic separator. The magnetic field strength was set at 500KA / m. The magnetic tailings were subjected to desulfurization flotation. The dosage of copper sulfate activator, butyl xanthate collector, and pine oil frother was 20g / t. The agent action time and flotation time were both 5m. in; the pH value of the desulfurized tailings is adjusted to about 11 using composite alkali; the dosage of Al-SBL inhibitor for cassiterite flotation is 400g / t, wherein the molar ratio of aluminum sulfate to water glass is 1:2; the dosage of metal-based multi-ligand collector is 600g / t, and the dosage of terpineol foaming agent is 30g / t; the selection reagent system is that the dosage of roughing inhibitor is gradually halved; respectively, 300g / t, 150g / t, and 75g / t, and the selected middlings are returned to the previous operation in sequence. After the gravity separation tailings and cassiterite flotation tailings are combined, the slurry concentration is adjusted to about 40wt%, and the pH is adjusted to about 9.7 using sodium carbonate. The inhibitor water glass of 1500g / t and the composite collector of 250g / t are used for fluorite roughing. The dosage of composite collector for scavenging is 80g / t. The roughing concentrate is wet-milled in an XMQ conical ball mill, and the grinding product enters the concentrating. The concentrating reagent system is as follows: the dosage of composite collector for concentrating is 50g / t, and the dosage of acidified water glass inhibitor is halved with the number of concentrating times, which is 600g / t, 300g / t, 150g / t, and 75g / t, respectively. The middlings from concentrating and scavenging are returned to the previous operation in sequence, and finally cassiterite and fluorite concentrates are obtained.

[0067] As can be seen from Table 4, by using the new process to treat cassiterite tailings, cassiterite concentrate with a SnO2 grade of 18.23% and a recovery rate of 61.63% and fluorite concentrate with a CaF2 grade of 88.11% and a recovery rate of 78.29% can be obtained, and the comprehensive recovery of cassiterite and fluorite is achieved at the same time. After the cassiterite tailings are classified by the spiral classifier, the returned sand is pre-discarded by a spiral chute, and the overflow is pre-discarded by a centrifuge, which greatly reduces the processing volume of the cassiterite flotation stage and is conducive to reducing the cost of grinding and reagents; the metal-based multi-ligand collector can selectively act on the oxygen sites on the surface of cassiterite, thereby having a selective inhibitory effect on fluorite, while achieving efficient recovery of fine-grained cassiterite and selective separation of cassiterite and fluorite. Fluorite and gangue minerals enter the flotation tailings together, and only a small amount of inhibitor is added to the rough selection of cassiterite, which will not have an adverse effect on the flotation of fluorite; a composite collector composed of fatty acids and heavy alkylbenzene sulfonates (HABS) is used to float fluorite. The combination of fatty acids and heavy alkylbenzene sulfonates has both collection ability and selectivity. Through the efficient synergistic effect of the two, the recovery of coarser-grained fluorite and undissociated fluorite intergrowths can be enhanced to ensure the recovery rate of rough selection. At the same time, the fluorite flotation section only needs to grind the coarse concentrate, which greatly reduces the grinding cost. This technical solution is simple to operate for the beneficiation of cassiterite tailings, has low reagent cost, and is highly applicable. It has guiding significance for the comprehensive recovery of fine-grained cassiterite and fluorite, and is conducive to further promotion and use.

[0068]

Claims

1. A beneficiation method for recovering fine particles of cassiterite and fluorite from cassiterite tailings, characterized in that: The following steps are involved: 1) After slurry adjustment, the cassiterite tailings are re-selected and classified using a spiral classifier. The returned sand from the classification is pre-selected in a spiral chute, and the overflow from the classification is pre-selected in a centrifugal concentrator. The pre-selected concentrate from the spiral chute and the pre-selected concentrate from the centrifugal concentrator are combined to obtain a mixed concentrate. 2) After grinding, the mixed concentrate is subjected to magnetic separation for iron removal and flotation for desulfurization to obtain desulfurized tailings; 3) After slurrying, the desulfurized tailings are subjected to cassiterite flotation using water glass modified with divalent or higher metal ions as an inhibitor and a metal-based multi-ligand organic complex as a collector to obtain cassiterite concentrate and flotation tailings; The metal-based multi-ligand organic complex is assembled by coordination of divalent or higher-valent metal ions with hydroxamic acids and alkylbenzene sulfonates; 4) After the flotation tailings are combined with the spiral chute pre-selection tailings and the centrifugal concentrator pre-selection tailings for slurry adjustment, fluorite flotation is carried out using water glass or acidified water glass as a depressant and fatty carboxylic acids and heavy alkylbenzene sulfonates as composite collectors to obtain fluorite concentrate.

2. A method for recovering fine-grained cassiterite and fluorite from cassiterite tailings according to claim 1, characterized in that: The cassiterite tailings are slurried to a concentration within the range of 25-35 wt.%; The spiral classifier has a classification angle of 15 to 25 degrees. The feed slurry concentration of the spiral chute is 25-30wt.%, and the pitch of the spiral chute is controlled within the range of 40-60mm; The feed slurry concentration of the centrifugal concentrator is 20~25wt.%, the rotation speed of the centrifugal concentrator is 500~800 r / min, the centrifugal acceleration is 250~300G, the operating pressure is 100~120PSI, the feeding time is 40~80s, the interval time is 5~15s, the flushing time is 10~15s, and the reset time is 5~15s.

3. A method for recovering fine-grained cassiterite and fluorite from cassiterite tailings according to claim 1, characterized in that: The mixed concentrate is ground to a particle size that satisfies a -0.074 mm particle size fraction of 80% to 85% by mass.

4. A method for recovering fine-grained cassiterite and fluorite from cassiterite tailings according to claim 1, characterized in that: The magnetic separation and iron removal adopts a drum-shaped wet weak magnetic separator, and the magnetic separation and iron removal process controls the ore pulp concentration to be 40-50wt.%, and the magnetic field strength to be 400-600KA / m.

5. A method for recovering fine-grained cassiterite and fluorite from cassiterite tailings according to claim 1, characterized in that: The reagent system of the flotation desulfurization is as follows: the dosage of copper sulfate activator is 100-200g / t, the dosage of butyl xanthate collector is 150-200g / t, and the dosage of pine oil as foaming agent is 25-30g / t.

6. A method for recovering fine-grained cassiterite and fluorite from cassiterite tailings according to claim 1, characterized in that: The divalent or higher metal ion modified water glass is obtained by compounding divalent or higher metal ions and water glass in a molar ratio of 1: (1-5), wherein the divalent or higher metal ions include Fe 2+ , Pb 2+ 、Cu 2+ Mg 2+ 、Al 3+ At least one of the following; The metal-based multi-ligand organic complex is assembled by coordination of divalent or higher metal ions with hydroxamic acids and alkylbenzene sulfonates in a molar ratio of (1-20): (1-10): 1, wherein the divalent or higher metal ions include Ca 2+ Mg 2+ 、Zn 2+ 、Fe 2+ , Pb 2+ 、Cu 2+ 、Mn 2+ 、Fe 3+ or Al 3+ At least one of the following; The hydroxamic acid includes at least one of benzohydroxamic acid, salicylic hydroxamic acid, and C7-C9 alkyl hydroxamic acid; The alkylbenzene sulfonates include C 10 ~C 14 At least one linear alkylbenzene sulfonate.

7. A method for recovering fine-grained cassiterite and fluorite from cassiterite tailings according to claim 1 or 6, characterized in that: The cassiterite flotation includes one roughing and 3 to 6 cleaning; The reagent system for the roughing is as follows: the pH adjuster is used to adjust the pH of the ore pulp to be within the range of 10.0-12.0, the dosage of the inhibitor is 100-500 g / t, the dosage of the collector is 500-1000 g / t, and the dosage of the foaming agent is 20-40 g / t; the pH adjuster is a composite alkali composed of NaOH and Na2CO3 in a mass ratio of (1-2):1; The selected drug system is as follows: the dosage of the inhibitor follows a step-by-step decrease.

8. A method for recovering fine-grained cassiterite and fluorite from cassiterite tailings according to claim 1, characterized in that: The fatty acids include at least one of oleic acid, linoleic acid, tall oil, lauric acid, linolenic acid, palmitic acid, stearic acid, erucic acid, and oxidized paraffin soap; The relative molecular mass of the heavy alkylbenzene sulfonate is 300-800; The composite collector is composed of fatty acids and heavy alkylbenzene sulfonates in a mass ratio of (1-5):

1.

9. A method for recovering fine-grained cassiterite and fluorite from cassiterite tailings according to claim 1 or 8, characterized in that: The fluorite flotation includes 1 roughing, 4 to 10 cleaning and 1 to 2 scavenging, and the roughing concentrate is regrinded; The reagent system for the roughing is as follows: pH adjuster is used to adjust the pH of the pulp to be within the range of 9.5 to 10.0, the dosage of water glass inhibitor is 1000 to 3000 g / t, and the dosage of composite collector is 100 to 300 g / t; The reagent system of the scavenging is as follows: the dosage of the composite collector is halved, and the scavenging sequence of the ore is returned to the previous operation; The selected reagent system is as follows: the dosage of the composite collector for the first selection is 50-100 g / t, the dosage of the acidified water glass inhibitor is 600-1000 g / t, and the dosage of other selected inhibitors follows a step-by-step decrease.

10. A beneficiation method for recovering fine particles of cassiterite and fluorite from cassiterite tailings according to claim 9, characterized in that: The regrinding process is to control the particle size to meet the mass content of the -0.074 mm particle size ≥85%.

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