Flotation method of calcite-containing fluorite

Abstract

The invention provides a calcite-containing fluorite flotation method, and belongs to the technical field of mineral flotation, and the calcite-containing fluorite flotation method comprises the following steps: grinding calcite-containing fluorite coarse ore, and mixing with water to obtain first ore pulp; adding a hydroxy carboxylic acid chelating agent to obtain second ore pulp; adding an inhibitor into the second ore pulp to obtain third ore pulp; a collecting agent is added into the third ore pulp, and fourth ore pulp is obtained; and a foaming agent is added into the fourth ore pulp for flotation, and fluorite concentrate is obtained. Based on a powerful calcium ion chelation reaction, the hydroxycarboxylic acid chelating agent and calcium ions on the surface of the calcite selectively form a stable complex, so that the surface hydrophilicity of the calcite is enhanced, chemical bonds with extremely high strength can be generated, fluorite precipitates on the surface of the calcite are replaced, and the surface hydrophilicity of the calcite is improved. The purposes of cleaning the calcite surface and eliminating the homogeneous transformation phenomenon are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of mineral flotation, and in particular to a flotation method for fluorite containing calcite. Background Art

[0002] Fluorite (CaF2) is a non-renewable strategic non-metallic mineral resource. Its main application area is the chemical industry. Almost 50% of fluorite is used to produce hydrofluoric acid (HF) and other downstream products. Fluorite is often associated with calcite. Calcite will seriously affect the stability of the hydrofluoric acid production system and introduce carbon dioxide (CO2) impurities, causing safety hazards, reducing product quality, and reducing economic benefits. It is the impurity mineral with the greatest impact on acid production. Therefore, it is very important to remove calcite from fluorite, and it is a necessary condition for fluorite to produce high-quality hydrofluoric acid.

[0003] The flotation separation of fluorite and calcite is extremely challenging. The fundamental reason is that the surface properties of the two are similar and homogeneous conversion occurs. The homogeneous conversion of fluorite and calcite is a process in which fluorite particles are precipitated on the surface of calcite through dissolution and precipitation reactions, and calcite is also generated on the surface of fluorite. This makes the surface chemical composition and physical and chemical properties such as hydrophilicity and hydrophobicity of fluorite and calcite more similar, which seriously affects the selective adsorption of flotation reagents. Therefore, eliminating homogeneous conversion is a prerequisite for achieving the precise removal of calcite from fluorite.

[0004] At present, the removal of difficult-to-separate calcite impurities is mainly done by developing calcite inhibitors with stronger inhibitory effects. The most commonly used inhibitors are sodium silicate, modified sodium silicate, sodium hexametaphosphate, starch, and sodium humate. However, the development and application of these inhibitors are all carried out under the premise that fluorite and calcite have not undergone homogeneous transformation, and the influence of mineral surface precipitation on the action and floatability of the reagent is not taken into account, resulting in unsatisfactory effects of these inhibitors in practical applications, and it is difficult to achieve the precise removal of trace calcite. The patent "A flotation method for improving the quality and reducing the calcium content of metallurgical-grade fluorite concentrate" (patent number: CN118681680A) uses a flotation method of one-stage roughing and four-stage concentrating to obtain a flotation concentrate with a grade of more than 90%. The flotation method improves the quality of fluorite in metallurgical-grade fluorite concentrate and effectively achieves the purpose of improving the quality and reducing the calcium content of metallurgical-grade fluorite concentrate. However, its flotation process is complicated, the dosage of inhibitors and regulators is about 1000 g / t, the dosage of collectors is about 500 g / t, and the dosage of reagents is large. The patent "A flotation reagent for inhibiting calcite in fluorite-barite paragenetic ore" (patent number: CN118341571A) uses 5-isosorbide mononitrate and water glass as inhibitors, sodium oleate and oxidized paraffin soap as collectors. After one roughing, two concentrating and two scavenging, the fluorite concentrate grade is more than 95% with a low dosage of reagents. However, the main impurity in the fluorite ore used is barite, and the calcite content is low (only 15.13%), and the method is not suitable for fluorite minerals with high calcite content. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present application provides a fluorite flotation method containing calcite, aiming to solve the following technical problems: ① the flotation separation of fluorite and calcite is difficult, and it is difficult to obtain high-grade fluorite concentrate; ② the method process is long and complicated, requiring complex method processes such as multiple stages of concentration and scavenging; ③ the amount of reagents used is large and there are many types, and a large amount of inhibitors are often used to suppress calcite.

[0006] In a first aspect, an embodiment of the present application provides a method for flotation of fluorite containing calcite, comprising the following steps: Grinding the fluorite coarse ore containing calcite and mixing it with water to prepare a first slurry; Adjusting the temperature and pH of the first slurry, adding a hydroxycarboxylic acid chelating agent thereto, stirring and reacting, and obtaining a second slurry; adding an inhibitor to the second slurry, stirring and reacting, and obtaining a third slurry; Adding a collector to the third slurry, stirring and reacting, to obtain a fourth slurry; A frother is added to the fourth slurry for flotation to obtain fluorite concentrate.

[0007] In some embodiments, the added amount of the hydroxycarboxylic acid chelating agent is 30-120 g / t; the hydroxycarboxylic acid chelating agent is at least one of 4-hydroxybenzoic acid, dihydroxyethylglycine, and sodium gluconate.

[0008] In some embodiments, the inhibitor is added in an amount of 50-200 g / t; the inhibitor is at least one of sodium silicate, modified sodium silicate, sodium hexametaphosphate, starch, and sodium humate.

[0009] In some embodiments, the amount of the collector added is 100-250 g / t; the collector is at least one of sodium oleate, oxidized paraffin soap, sodium dodecyl sulfate, and tall oil.

[0010] In some embodiments, the amount of foaming agent added is 10-40 g / t.

[0011] In some embodiments, the particle size of the fluorite coarse ore containing calcite in the first slurry is 38-150 μm, and the concentration of the first slurry is 15%-30%.

[0012] In some embodiments, the stirring reaction time is 2 to 10 minutes.

[0013] In some embodiments, flotation comprises the steps of: A frother is added to the fourth pulp for roughing, the roughing concentrate is subjected to three consecutive cleanings, and the roughing tailings are subjected to one scavenging; The concentrate from each round of concentration enters the next round of concentration, the tailings from the first round of concentration are returned to the roughing round, and the tailings from the second and third rounds of concentration are returned to the previous round of concentration. The final flotation foam is the fluorite concentrate. The scavenging concentrate is returned to the roughing and the scavenging tailings are discharged.

[0014] In some embodiments, inhibitors and collectors are added during the second and third stages of concentration, and the mass of the inhibitor added in the second stage of concentration is 5% to 15% of the mass of the inhibitor added in the roughing stage; the mass of the collector added in the second stage of concentration is 10% to 30% of the mass of the collector added in the roughing stage; the mass of the inhibitor added in the third stage of concentration is 2% to 10% of the mass of the inhibitor added in the roughing stage; and the mass of the collector added in the third stage of concentration is 5% to 15% of the mass of the collector added in the roughing stage.

[0015] In some embodiments, the flotation stirring speed is 800-1500 r / min.

[0016] In some embodiments, the flotation aeration volume is 0.1-0.4 m 3 / h, flotation time is 5~15min.

[0017] Different from the existing technical solutions, the beneficial effects of this application include: 1. This application adds hydroxycarboxylic acid chelating agents to cooperate with inhibitors to effectively inhibit calcite. The types of reagents used are small, the cost is low, and the method process is simple and easy to control. Based on the strong calcium ion chelation reaction, the hydroxycarboxylic acid chelating agent selectively forms a stable complex with the calcium ion on the surface of calcite, which not only enhances the hydrophilicity of the calcite surface, but also generates extremely strong chemical bonds, thereby replacing the fluorite precipitate on the surface of calcite, achieving the purpose of cleaning the calcite surface and eliminating the homogeneous conversion phenomenon, and ultimately enhancing the inhibitory effect of the inhibitor on calcite. Under low reagent dosage conditions, the flotation index of CaF2 grade of 98.23% and recovery rate of 96.45% can be achieved after three stages of selection and one stage of scavenging.

[0018] 2. In the flotation method of the present application, a hydroxycarboxylic acid chelating agent is first used to react with calcium ions in calcite to generate a chemical bond with extremely high strength, thereby replacing the fluorite precipitate on the surface of the calcite, achieving the purpose of cleaning the surface of the calcite and eliminating the phenomenon of homogeneous transformation, and finally enhancing the inhibitory effect of the inhibitor on calcite. Based on the above-mentioned hydroxycarboxylic acid chelating agent, a method for eliminating the homogeneous transformation of fluorite associated with calcium carbonate has been developed, which can effectively promote the fluorite precipitate to fall off the surface of calcite, expose the fresh surface of calcite and eliminate the influence of homogeneous transformation, creating favorable conditions for the subsequent adsorption of inhibitors.

[0019] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is a flow chart of the fluorite flotation method in this application.

[0022] Figure 2 The test results of CaF2 grade and recovery rate of fluorite concentrates prepared in Examples 1 to 5 and Comparative Examples 1 to 3 are shown.

[0023] Figure 3 Figure 3 is the SEM scan of homogenized calcite before and after the reaction with sodium gluconate, where 3 (a) is the SEM scan of homogenized calcite; 3 (b) is the SEM scan of homogenized calcite after the reaction with sodium gluconate. DETAILED DESCRIPTION

[0024] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0026] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0027] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0028] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0029] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0030] At present, the removal of difficult-to-separate calcite impurities is mainly done by developing calcite inhibitors with stronger inhibitory effects. The most commonly used inhibitors are sodium silicate, modified sodium silicate, sodium hexametaphosphate, starch, and sodium humate. However, the development and application of these inhibitors are all carried out under the premise that fluorite and calcite have not undergone homogeneous transformation, and the influence of mineral surface precipitation on the action and floatability of the reagent is not taken into account, resulting in unsatisfactory effects of these inhibitors in practical applications, and it is difficult to achieve the precise removal of trace calcite.

[0031] In order to solve the following problems: ① the flotation separation of fluorite and calcite is difficult, and it is difficult to obtain high-grade fluorite concentrate; ② the method flow is long and complicated, requiring complex method flows such as multi-stage selection and scavenging; ③ the dosage of reagents is large, the types are many, and a large amount of inhibitors are often used to inhibit calcite. The present application provides a fluorite flotation method containing calcite, wherein by adding hydroxycarboxylic acid chelating agents, synergistic inhibitors are used to efficiently inhibit calcite, the types of reagents used are small, the cost is low, and the method flow is simple and easy to control. Based on the strong calcium ion chelation reaction, the hydroxycarboxylic acid chelating agent selectively forms a stable complex with the calcium ion on the surface of calcite, which not only enhances the hydrophilicity of the calcite surface, but also generates extremely strong chemical bonds, thereby replacing the fluorite precipitation on the surface of calcite, achieving the purpose of cleaning the calcite surface and eliminating the phenomenon of homogeneous conversion, and finally enhancing the inhibitory effect of the inhibitor on calcite. Under the condition of low dosage of reagents, the flotation index of CaF2 grade of 98.23% and recovery rate of 96.45% can be achieved by three stages of selection and one stage of scavenging.

[0032] First, as Figure 1 As shown, the embodiment of the present application provides a method for flotation of fluorite containing calcite, comprising the following steps: Grinding the fluorite coarse ore containing calcite and mixing it with water to prepare a first slurry; Adjusting the temperature and pH of the first slurry, adding a hydroxycarboxylic acid chelating agent thereto, stirring and reacting, and obtaining a second slurry; adding an inhibitor to the second slurry, stirring and reacting, and obtaining a third slurry; Adding a collector to the third slurry, stirring and reacting, to obtain a fourth slurry; A frother is added to the fourth slurry for flotation to obtain fluorite concentrate.

[0033] In some embodiments, the added amount of the hydroxycarboxylic acid chelating agent is 30-120 g / t; the hydroxycarboxylic acid chelating agent is at least one of 4-hydroxybenzoic acid, dihydroxyethylglycine, and sodium gluconate.

[0034] In some embodiments, the inhibitor is added in an amount of 50-200 g / t; the inhibitor is at least one of sodium silicate, modified sodium silicate, sodium hexametaphosphate, starch, and sodium humate.

[0035] In some embodiments, the amount of the collector added is 100-250 g / t; the collector is at least one of sodium oleate, oxidized paraffin soap, sodium dodecyl sulfate, and tall oil.

[0036] In some embodiments, the amount of foaming agent added is 10-40 g / t.

[0037] In the technical scheme of the embodiment of the present application, hydroxycarboxylic acid is an organic compound containing at least one hydroxyl or carboxyl group in its molecular structure. Since the hydroxyl and carboxyl groups are polar, they can quickly form hydrogen bonds with water and become hydrophilic. In addition, hydroxycarboxylic acid is a calcium ion chelating agent, which has the ability to undergo strong chemical adsorption and complexation reaction with calcium ions on the surface of fluorite and calcite to form extremely stable chelates. This strong chemical adsorption can replace the chemical bond between the fluorite or calcite precipitate and the mineral surface, thereby forming a hydrophilic chelating substance on the mineral surface, desorbing the mineral precipitate on the surface of fluorite and calcite, and ultimately eliminating the negative impact of homogeneous conversion.

[0038] This application uses typical hydroxycarboxylic acid chelating agents 4-hydroxybenzoic acid (C7H6O3), dihydroxyethylglycine (C6H 13 NO4), sodium gluconate (C6H 11 O7Na) become synergistic inhibitors of calcite after homogeneous conversion. Due to the strong complexation of hydroxycarboxylic acid chelating agents with calcium ions on the surface of minerals, mineral precipitation on the surface of fluorite and calcite is removed, and the adverse effects of homogeneous conversion on flotation separation are removed, creating favorable conditions for the deep removal of calcite.

[0039] In some embodiments, the particle size of the fluorite coarse ore containing calcite in the first slurry is 38-150 μm, and the concentration of the first slurry is 15%-30%.

[0040] In some embodiments, the temperature of the first slurry is 15-35° C., and the pH value is 7-11.

[0041] In some embodiments, the stirring reaction time is 2 to 10 minutes.

[0042] In some embodiments, Figure 1 As shown, flotation includes the following steps: A frother is added to the fourth pulp for roughing, the roughing concentrate is subjected to three consecutive cleanings, and the roughing tailings are subjected to one scavenging; The concentrate from each round of concentration enters the next round of concentration, the tailings from the first round of concentration are returned to the roughing round, and the tailings from the second and third rounds of concentration are returned to the previous round of concentration. The final flotation foam is the fluorite concentrate. The scavenging concentrate is returned to the roughing and the scavenging tailings are discharged.

[0043] In the technical solution of the embodiment of the present application, the carboxylic acid chelating agent is added to the first slurry before the inhibitor, and interacts with the fluorine-containing precipitation on the surface of the calcite to remove the fluorite precipitation on its surface and eliminate its adverse effect on flotation, and then the inhibitor is added to enhance the inhibitor's inhibitory effect. This can greatly reduce the dosage of the inhibitor (the dosage of sodium silicate in the present application is 50~200 g / t) and shorten the flotation process (three times of concentration and one scavenging in the present application), thereby further improving the flotation effect and reducing costs.

[0044] In some embodiments, Figure 1 As shown, the mass of inhibitor added in the second cleaning (fine II) is 5%~15% of that in the roughing; the mass of collector added in the second cleaning is 10%~30% of that in the roughing; the mass of inhibitor added in the third cleaning (fine III) is 2%~10% of that in the roughing; the mass of collector added in the third cleaning is 5%~15% of that in the roughing.

[0045] In some embodiments, the flotation stirring speed is 800-1500 r / min.

[0046] In some embodiments, the flotation aeration volume is 0.1-0.4 m 3 / h, flotation time is 5~15min.

[0047] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0048] 1. Preparation method The mineral sample used in the embodiments of the present application is an artificial mixed ore of fluorite with a purity of 99.1% and calcite with a purity of 99.4% (the mass fraction of each is 50%), so as to simulate the associated fluorite mineral containing a large amount of calcite.

[0049] Example 1 A method for flotation of fluorite containing calcite, comprising the following steps: S1. Mix the mineral samples of fluorite and calcite with a particle size of 38-150 μm with ultrapure water to prepare a slurry with a slurry concentration of 17%. Adjust the slurry pH to 9 and control the temperature to 25°C. Add 20 g / t of 4-hydroxybenzoic acid, 20 g / t of dihydroxyethylglycine, and 20 g / t of sodium gluconate. React for 2 min. Then add 100 g / t of sodium silicate as an inhibitor. React for 2 min. Then add 200 g / t of sodium oleate. React for 5 min.

[0050] S2. Add 20 g / t methyl isobutyl carbinol to the slurry for roughing. The roughing concentrate is subjected to three consecutive cleanings, and the roughing tailings are subjected to one scavenging. The mass of sodium silicate added in the second and third cleanings is 10% and 5% of the mass of sodium silicate added in the roughing, respectively. The mass of collector added in the second and third cleanings is 15% and 10% of the mass of collector added in the roughing, respectively.

[0051] The concentrate from each round of concentration enters the next round of concentration, the tailings from the first round of concentration are returned to the roughing round, and the tailings from the second and third rounds of concentration are returned to the previous round of concentration. The final flotation foam is the fluorite concentrate. The scavenging concentrate is returned to the roughing and the scavenging tailings are discharged.

[0052] The stirring speed is 1200 r / min and the aeration volume is 0.1 m 3 / h, the scraping time is 10 min, and the flotation foam obtained in the third concentration is fluorite concentrate.

[0053] The CaF2 grade of the obtained concentrate is 98.23% and the recovery rate is 96.45%.

[0054] Example 2 A method for flotation of fluorite containing calcite, comprising the following steps: S1. Mix the mineral sample of fluorite and calcite with a particle size of 38-150 μm with ultrapure water to prepare a slurry with a slurry concentration of 15%. Adjust the slurry pH to 11 and control the temperature to 35°C. Add 40 g / t of 4-hydroxybenzoic acid, 40 g / t of dihydroxyethylglycine, and 40 g / t of sodium gluconate. React for 10 min. Then add 200 g / t of sodium silicate as an inhibitor. React for 10 min. Then add 250 g / t of sodium oleate. React for 10 min.

[0055] S2. Add 10 g / t methyl isobutyl carbinol to the slurry for roughing. The roughing concentrate is subjected to three consecutive cleanings, and the roughing tailings are subjected to one scavenging. The mass of sodium silicate added in the second and third cleanings is 5% and 2% of the mass of sodium silicate added in the roughing, respectively. The mass of collector added in the second and third cleanings is 10% and 5% of the mass of collector added in the roughing, respectively.

[0056] The concentrate from each round of concentration enters the next round of concentration, the tailings from the first round of concentration are returned to the roughing round, and the tailings from the second and third rounds of concentration are returned to the previous round of concentration. The final flotation foam is the fluorite concentrate. The scavenging concentrate is returned to the roughing and the scavenging tailings are discharged.

[0057] The stirring speed is 800 r / min and the aeration volume is 0.4 m 3 / h, the scraping time is 5 min, and the flotation foam obtained in the third concentration is fluorite concentrate.

[0058] The CaF2 grade of the obtained concentrate is 98.76% and the recovery rate is 93.46%.

[0059] Example 3 A method for flotation of fluorite containing calcite, comprising the following steps: S1. Mix the mineral sample of fluorite and calcite with a particle size of 38-150 μm with ultrapure water to prepare a slurry with a slurry concentration of 25%. Adjust the slurry pH to 8 and control the temperature to 15°C. Add 10 g / t of 4-hydroxybenzoic acid, 10 g / t of dihydroxyethylglycine, and 10 g / t of sodium gluconate. React for 2 min. Then add 50 g / t of sodium silicate as an inhibitor. React for 2 min. Then add 100 g / t of sodium oleate. React for 2 min.

[0060] S2. Add 40 g / t methyl isobutyl carbinol to the slurry for roughing. The roughing concentrate is subjected to three consecutive cleanings, and the roughing tailings are subjected to one scavenging. The mass of sodium silicate added in the second and third cleanings is 15% and 10% of the mass of sodium silicate added in the roughing, respectively. The mass of collector added in the second and third cleanings is 30% and 15% of the mass of collector added in the roughing, respectively.

[0061] The concentrate from each round of concentration enters the next round of concentration, the tailings from the first round of concentration are returned to the roughing round, and the tailings from the second and third rounds of concentration are returned to the previous round of concentration. The final flotation foam is the fluorite concentrate. The scavenging concentrate is returned to the roughing and the scavenging tailings are discharged.

[0062] The stirring speed is 1500 r / min and the aeration volume is 0.4 m 3 / h, the scraping time is 15 min, and the flotation foam obtained in the third concentration is fluorite concentrate.

[0063] The CaF2 grade of the obtained concentrate is 97.62% and the recovery rate is 96.58%.

[0064] Example 4 A method for flotation of fluorite containing calcite, comprising the following steps: S1. Mix the mineral sample of fluorite and calcite with a particle size of 38-150 μm with ultrapure water to prepare a slurry with a slurry concentration of 20%. Adjust the slurry pH to 10 and control the temperature to 30°C. Add 30 g / t of 4-hydroxybenzoic acid, 30 g / t of dihydroxyethylglycine, and 30 g / t of sodium gluconate. React for 8 min. Then add 150 g / t of sodium silicate as an inhibitor. React for 8 min. Then add 200 g / t of sodium oleate. React for 8 min.

[0065] S2. 15 g / t methyl isobutyl carbinol was added to the slurry for roughing. The roughing concentrate was subjected to three consecutive cleanings, and the roughing tailings were subjected to one scavenging. The mass of sodium silicate added in the second and third cleanings was 8% and 4% of the mass of sodium silicate added in the roughing, respectively. The mass of collector added in the second and third cleanings was 15% and 8% of the mass of collector added in the roughing, respectively.

[0066] The concentrate from each round of concentration enters the next round of concentration, the tailings from the first round of concentration are returned to the roughing round, and the tailings from the second and third rounds of concentration are returned to the previous round of concentration. The final flotation foam is the fluorite concentrate. The scavenging concentrate is returned to the roughing and the scavenging tailings are discharged.

[0067] The stirring speed is 1000 r / min and the aeration volume is 0.2 m 3 / h, the scraping time is 7 min, and the flotation foam obtained in the third concentration is fluorite concentrate.

[0068] The CaF2 grade of the obtained concentrate is 98.41% and the recovery rate is 94.60%.

[0069] Example 5 A method for flotation of fluorite containing calcite, comprising the following steps: S1. Mix the mineral sample of fluorite and calcite with a particle size of 38-150 μm with ultrapure water to prepare a slurry with a slurry concentration of 20%. Adjust the slurry pH to 8 and control the temperature to 20°C. Add 15 g / t of 4-hydroxybenzoic acid, 15 g / t of dihydroxyethylglycine, and 15 g / t of sodium gluconate. React for 4 min. Then add 80 g / t of sodium silicate as an inhibitor. React for 4 min. Then add 150 g / t of sodium oleate. React for 4 min.

[0070] S2. Add 30 g / t methyl isobutyl carbinol to the slurry for roughing. The roughing concentrate is subjected to three consecutive cleanings, and the roughing tailings are subjected to one scavenging. The mass of sodium silicate added in the second and third cleanings is 12% and 8% of the mass of sodium silicate added in the roughing, respectively. The mass of collector added in the second and third cleanings is 25% and 12% of the mass of collector added in the roughing, respectively.

[0071] The concentrate from each round of concentration enters the next round of concentration, the tailings from the first round of concentration are returned to the roughing round, and the tailings from the second and third rounds of concentration are returned to the previous round of concentration. The final flotation foam is the fluorite concentrate. The scavenging concentrate is returned to the roughing and the scavenging tailings are discharged.

[0072] The stirring speed is 1300 r / min and the aeration volume is 0.3 m 3 / h, the scraping time is 12 min, and the flotation foam obtained in the third concentration is fluorite concentrate.

[0073] The CaF2 grade of the obtained concentrate is 97.83% and the recovery rate is 96.23%.

[0074] Comparative Example 1 The difference between this comparative example and Example 1 is that none of 4-hydroxybenzoic acid, dihydroxyethylglycine and sodium gluconate is added, and the CaF2 grade of the obtained concentrate is 89.53%, and the recovery rate is 97.99%.

[0075] Comparative Example 2 The only difference between this comparative example and Example 1 is that 100 g / t 4-hydroxybenzoic acid, 100 g / t dihydroxyethylglycine, and 100 g / t sodium gluconate are added, and the CaF2 grade of the obtained concentrate is 98.94%, and the recovery rate is 92.89%.

[0076] Comparative Example 3 The only difference between this comparative example and Example 1 is that the inhibitor sodium silicate is not added, and the CaF2 grade of the obtained concentrate is 59.23%, and the recovery rate is 97.34%.

[0077] Comparative Example 4 Comparative Example 4 is different from Example 1 in that 4-hydroxybenzoic acid, dihydroxyethylglycine, sodium gluconate and sodium silicate are added to the slurry at the same time for reaction, comprising the following steps: S1. Mix the mineral samples of fluorite and calcite with a particle size of 38-150 μm with ultrapure water to prepare a slurry with a slurry concentration of 17%. Adjust the slurry pH to 9 and control the temperature to 25 °C. Add 20 g / t of 4-hydroxybenzoic acid, 20 g / t of dihydroxyethylglycine, 20 g / t of sodium gluconate, and 100 g / t of inhibitor sodium silicate. React for 2 min, then add 200 g / t of sodium oleate and react for 5 min.

[0078] S2. Add 20 g / t methyl isobutyl carbinol to the slurry for roughing. The roughing concentrate is subjected to three consecutive cleanings, and the roughing tailings are subjected to one scavenging. The mass of sodium silicate added in the second and third cleanings is 10% and 5% of the mass of sodium silicate added in the roughing, respectively. The mass of collector added in the second and third cleanings is 15% and 10% of the mass of collector added in the roughing, respectively.

[0079] The concentrate from each round of concentration enters the next round of concentration, the tailings from the first round of concentration are returned to the roughing round, and the tailings from the second and third rounds of concentration are returned to the previous round of concentration. The final flotation foam is the fluorite concentrate. The scavenging concentrate is returned to the roughing and the scavenging tailings are discharged.

[0080] The scavenged concentrate is returned to the first cleaning process, with a stirring speed of 1200 r / min and an aeration volume of 0.1 m 3 / h, the scraping time is 10 min, and the flotation foam obtained in the third concentration is fluorite concentrate.

[0081] The CaF2 grade of the obtained concentrate is 92.75% and the recovery rate is 95.87%.

[0082] 2. Test Method The CaF2 grade of the concentrate is determined in accordance with the method specified in the Chinese national standard GB / T 5195.1-2017 Determination of calcium fluoride content in fluorite by EDTA titration and distillation-potentiometric titration. The concentrate yield is determined by the percentage of the concentrate mass to the original ore mass.

[0083] The recovery rate of CaF2 in the concentrate is determined by the following formula: Recovery rate = (concentrate grade × yield / ore grade) × 100%.

[0084] III. Analysis of test results of various embodiments and comparative examples (1) The CaF2 grade and recovery rate of the concentrates obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were tested. The test results are shown in Figure 2 .from Figure 2It can be seen that in Comparative Example 1, when hydroxycarboxylic acid chelating agents 4-hydroxybenzoic acid, dihydroxyethylglycine, and sodium gluconate are not added, the grade of fluorite concentrate is low, only 89.53%, indicating that when hydroxycarboxylic acid chelating agents are not added, it is difficult to achieve efficient separation of fluorite and calcite using only 100 g / t sodium silicate and 200 g / t sodium oleate. From Examples 1 to 5 and Comparative Example 2, it can be seen that when the amount of hydroxycarboxylic acid chelating agents increases, the grade of fluorite concentrate is not significantly improved, while the recovery rate is reduced to 92.89%, indicating that excessive hydroxycarboxylic acid chelating agents inhibit fluorite flotation and have an adverse effect on the separation of the two, and the amount of hydroxycarboxylic acid chelating agents should not be too high. It can be seen from Examples 1 to 5 and Comparative Example 3 that without adding the inhibitor sodium silicate, the grade of fluorite concentrate is greatly reduced to 59.23%, indicating that hydroxycarboxylic acid chelating agents cannot be used alone as inhibitors and their flotation inhibitory effect on calcite is not strong.

[0085] It can be seen from Examples 1 to 5 and Comparative Example 4 that when 4-hydroxybenzoic acid, dihydroxyethylglycine, sodium gluconate and sodium silicate are added to the pulp at the same time, the fluorite concentrate grade is low, at 92.75%, indicating that the addition of a hydroxycarboxylic acid chelating agent mixed with sodium silicate will reduce its inhibitory effect, mainly because the carboxylic acid chelating agent needs to react with the fluoritized cover layer on the surface of the calcite to cause it to fall off. If sodium silicate is added when the fluoritized cover layer has not completely fallen off, the sodium silicate cannot be effectively adsorbed on the fluoritized calcite surface, resulting in a waste of reagents and reducing its inhibitory effect.

[0086] (2) If Figure 3 As shown, in order to more significantly demonstrate the exfoliation and activation effect of hydroxycarboxylic acid chelating agents on the surface of homogenized calcite, SEM tests were carried out on the homogenized calcite samples before and after the action of sodium gluconate to characterize the changes in their surface morphology. The results show that spherical fluorite precipitates were observed on the surface of homogenized calcite, resulting in the calcite surface showing properties similar to fluorite. However, after treatment with sodium gluconate, the precipitates on the surface of calcite were effectively removed, restoring the original surface characteristics of calcite, thereby enhancing the inhibitory effect of sodium silicate on calcite.

[0087] This method can effectively separate fluorite and calcite by flotation, with the fluorite concentrate grade reaching 98.23% and the recovery rate reaching 96.45%. At the same time, it can effectively shorten the flotation process, reduce the dosage of reagents, and reduce the flotation cost. Compared with the traditional method, this method has a higher calcite removal rate and more thorough flotation separation of fluorite and calcite.

[0088] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for flotation of fluorite containing calcite, characterized in that: The steps include: Grinding the fluorite coarse ore containing calcite and mixing it with water to prepare a first slurry; Adjusting the temperature and pH of the first slurry, adding a hydroxycarboxylic acid chelating agent thereto, stirring and reacting, and obtaining a second slurry; adding an inhibitor to the second slurry, stirring and reacting, to obtain a third slurry; adding a collector to the third slurry, stirring and reacting, to obtain a fourth slurry; A frother is added to the fourth slurry for flotation to obtain fluorite concentrate.

2. The fluorite flotation method according to claim 1, characterized in that: The added amount of the hydroxycarboxylic acid chelating agent is 30-120 g / t; the hydroxycarboxylic acid chelating agent is at least one of 4-hydroxybenzoic acid, dihydroxyethylglycine, and sodium gluconate.

3. The fluorite flotation method according to claim 1, characterized in that: The added amount of the inhibitor is 50-200 g / t; the inhibitor is at least one of sodium silicate, modified sodium silicate, sodium hexametaphosphate, starch, and sodium humate.

4. The fluorite flotation method according to claim 1, characterized in that: The added amount of the collector is 100-250 g / t; the collector is at least one of sodium oleate, oxidized paraffin soap, sodium dodecyl sulfate, and tall oil.

5. The fluorite flotation method according to claim 1, characterized in that: The added amount of the foaming agent is 10-40 g / t.

6. The fluorite flotation method according to claim 1, characterized in that: The particle size of the fluorite coarse ore containing calcite in the first slurry is 38-150 μm, and the concentration of the first slurry is 15%-30%.

7. The fluorite flotation method according to claim 1, characterized in that: The temperature of the first slurry is 15-35° C., and the pH value is 7-11.

8. The fluorite flotation method according to claim 1, characterized in that: The flotation comprises the following steps: Adding a frother to the fourth slurry for roughing, performing three consecutive cleanings on the roughing concentrate, and performing one scavenging on the roughing tailings; The concentrate from each round of concentration enters the next round of concentration, the tailings from the first round of concentration are returned to the roughing round, and the tailings from the second and third rounds of concentration are returned to the previous round of concentration. The final flotation foam is the fluorite concentrate. The scavenging concentrate is returned to the roughing and the scavenging tailings are discharged.

9. The fluorite flotation method according to claim 8, characterized in that: Inhibitors and collectors are added during the second and third stages of concentration. The mass of inhibitors added in the second stage of concentration is 5%~15% of that added in the roughing stage; the mass of collectors added in the second stage of concentration is 10%~30% of that added in the roughing stage; the mass of inhibitors added in the third stage of concentration is 2%~10% of that added in the roughing stage; the mass of collectors added in the third stage of concentration is 5%~15% of that added in the roughing stage.

10. The fluorite flotation method according to claim 1, characterized in that: The flotation stirring speed is 800-1500 r / min; the flotation aeration volume is 0.1-0.4 m 3 / h, flotation time is 5~15min.

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