Combined cassiterite flotation inhibitor and application thereof

Abstract

The invention discloses a cassiterite flotation combined inhibitor and application thereof. The combined inhibitor is composed of N-(phosphoryl methyl) glycine and carboxymethyl cellulose. According to the invention, N-(phosphoryl methyl) glycine and carboxymethyl cellulose are synergistically compounded, N-(phosphoryl methyl) glycine is used as a molecular anchoring agent, and accurate recognition and locking of calcium active sites on the surfaces of calcite, fluorite and other minerals are realized through specific chelation; carboxymethyl cellulose serves as a space barrier and a film-forming agent, a compact, hydrophilic and stable three-dimensional coating film is formed on the basis of anchoring, and long-acting three-dimensional shielding is provided; the cassiterite and the calcium-containing gangue have complementary functions and synergistic interaction, and high-strength and high-selectivity inhibition on the calcium-containing gangue can be realized on the premise of basically not influencing the floatability of the cassiterite, so that the separation efficiency of the cassiterite and the calcium-containing gangue minerals and the concentrate quality are remarkably improved; the inhibition effect is lasting and stable, the calcium impurity content in the tin concentrate can be effectively reduced, and the tin concentrate quality and the separation efficiency are improved.

Description

Technical Field

[0001] This invention relates to a cassiterite flotation combination inhibitor and its application, belonging to the field of mineral flotation separation technology. Background Technology

[0002] Tin is generally considered an important strategic non-ferrous metal, with cassiterite being its primary industrial mineral. Cassiterite flotation is a core process for the efficient recovery and purification of tin resources. In the flotation of complex cassiterite-co-existing ores, the efficient separation of calcareous gangue minerals such as calcite and fluorite from cassiterite has always been a common challenge in the industry. Calcium-containing gangue minerals have numerous active Ca²⁺ sites on their surfaces, and their floatability highly overlaps with that of cassiterite. They are prone to rising simultaneously with cassiterite during flotation, leading to excessive calcium content in the tin concentrate and low separation efficiency, severely restricting the efficient utilization of cassiterite resources.

[0003] Currently, existing depressants used in cassiterite flotation generally suffer from technical defects such as poor selectivity, inadequate inhibition effect, and poor environmental compatibility. Traditional inorganic depressants, such as water glass, have limited adsorption selectivity for calcium-containing gangue, requiring excessive addition to achieve the desired inhibition effect, which can easily lead to fine mud covering in the pulp and interfere with normal cassiterite flotation. Although sodium hexametaphosphate can complex Ca²⁺, its non-selective action can destroy the active sites on the cassiterite surface, reducing cassiterite recovery. Some small molecule depressants or heavy metal salt depressants, while possessing certain inhibition effects, suffer from high toxicity and can easily cause process pollution, failing to meet the requirements of green mineral processing. Furthermore, single organic depressants such as tannic acid and carboxymethyl cellulose cannot simultaneously achieve the synergistic effects of "precise adsorption, long-lasting hydrophilicity, and three-dimensional shielding." Tannic acid adsorption layers have poor stability, and carboxymethyl cellulose (CMC) has insufficient selectivity, easily causing non-specific inhibition of cassiterite, making it difficult to meet the high-efficiency separation requirements of complex cassiterite ores.

[0004] Therefore, developing a new and highly efficient cassiterite flotation combination inhibitor is the key to solving the above-mentioned technical problems. Summary of the Invention

[0005] In view of the many defects and shortcomings of the above-mentioned background technology, the present invention has made improvements and innovations, aiming to provide a cassiterite flotation combination inhibitor with strong inhibition effect and environmentally friendly and its application. By enhancing the adsorption capacity on the surface of calcium gangue minerals and improving the hydrophobicity of the cassiterite surface, the present invention achieves efficient and highly selective flotation separation of cassiterite and calcium gangue minerals.

[0006] To solve the above problems and achieve the above-mentioned objectives, the present invention provides a cassiterite flotation combination inhibitor and its application, which is achieved by adopting the following design structure and the following technical solution:

[0007] A cassiterite flotation inhibitor composed of N-(phosphorylmethyl)glycine and carboxymethyl cellulose.

[0008] Preferably, the N-(phosphorylmethyl)glycine is analytical grade, with a purity ≥95%, and is in powder form; the carboxymethyl cellulose is type I, MW 700000 (DS=0.9), 2500~4500mPa.s;

[0009] The mass ratio of N-(phosphorylmethyl)glycine to carboxymethyl cellulose is 0.5–1.5:1.

[0010] Preferably, the combined inhibitor is used in the flotation separation process of cassiterite and calcium-containing minerals.

[0011] Preferably, the flotation includes one roughing, two to four sweeping, and two to three cleaning processes, with the combined inhibitor added during the roughing and cleaning processes.

[0012] Preferably, the amount of combined inhibitor added during the first coarse selection process is 200-400 g / t.

[0013] Preferably, the application includes the following steps:

[0014] (1) Prepare cassiterite slurry and adjust the pH of the slurry to 8-10;

[0015] (2) Add activator, inhibitor and collector to the slurry in sequence, and carry out roughing to obtain rough concentrate and rough tailings;

[0016] (3) Add a collector to the obtained coarse tailings and perform 2 to 4 scavenging operations to obtain scavenged concentrate. No frother is added in the last scavenging operation.

[0017] (4) Add inhibitors to the obtained crude concentrate and perform 2 to 3 fine selections to obtain tin concentrate.

[0018] Preferably, in the roughing process, the activator is lead acetate, and the addition amount is 50-100 g / t;

[0019] The amount of the combined inhibitor added is 200-400 g / t;

[0020] The collector is sodium oleate, and the addition amount is 800-1200 g / t.

[0021] Preferably, in the 2nd to 4th scavenging processes, the collector is sodium oleate, and the amount of collector added in scavenging operation I is 400-600 g / t; the amount of collector added in scavenging operation II is 200-300 g / t; the amount of collector added in scavenging operation III is 100-150 g / t; and the amount of collector added in scavenging operation IV is 50-75 g / t.

[0022] Preferably, in the 2-3 selection processes, the amount of inhibitor added in selection process I is 100-200 g / t, the amount of inhibitor added in selection process II is 50-100 g / t, and the amount of inhibitor added in selection process III is 25-50 g / t.

[0023] Preferably, the combined inhibitor is added in the form of an aqueous solution with a mass percentage concentration of 0.5% to 1%;

[0024] The lead acetate is added in the form of an aqueous solution with a mass percentage concentration of 1-5%.

[0025] The sodium oleate is added in the form of an aqueous solution with a mass percentage concentration of 1-5%.

[0026] Working Principle: This invention achieves a breakthrough improvement in the inhibition effect on calcium-containing gangue minerals during cassiterite flotation through a three-pronged synergistic mechanism of "molecular anchoring - three-dimensional film formation - synergistic stabilization". In terms of molecular structure design and synergistic effect, N-(phosphonomethyl)glycine, as a small molecule inhibitor, has a phosphonate group (-PO3H2) and a carboxyl group (-COOH) forming a pair of spatially matched and charge-complementary "functional group clamps". These clamps preferentially and specifically chelate with Ca²⁺ on the surface of calcium-containing minerals such as calcite and fluorite, forming stable bidentate or multi-ring complexes, thereby achieving highly selective molecular anchoring and establishing a precise starting point for subsequent inhibition. Carboxymethyl cellulose, as a high-molecular-weight inhibitor, has a long-chain backbone rich in hydroxyl and carboxymethyl groups. It can extend and adsorb onto the anchored gangue surface through hydrogen bonds, electrostatic attraction, and van der Waals forces, thereby constructing a dense, thick, and highly hydrophilic three-dimensional protective film, providing durable spatial shielding and physical barrier. The synergistic effect of the two is manifested in deep functional complementarity and enhancement: the precise anchoring of N-(phosphorylmethyl)glycine ensures the selectivity of the inhibition process, avoiding the encapsulation of cassiterite by polymeric inhibitors due to non-selective adsorption; the stereochemical film formation of carboxymethyl cellulose solves the problem of thin adsorption layers of small molecule inhibitors, which are susceptible to fluid shear or mechanical detachment, thus achieving long-term stability of the inhibition effect. On this basis, the combined system further enhances the inhibition efficacy through synergistic hydration and stereochemical shielding: the hydrophilic groups of N-(phosphorylmethyl)glycine that do not participate in coordination and the polar groups on the carboxymethyl cellulose chain jointly construct a strengthened hydrogen bond network, greatly enhancing the strength of the hydration layer on the gangue surface; at the same time, the long chain structure of carboxymethyl cellulose generates significant steric hindrance, kinetically blocking the approach and adsorption of hydrophobic collectors to the gangue surface. This multi-level synergistic approach of "anchoring-film formation-hydration-shielding" significantly broadens the buoyancy difference between cassiterite and calcium-bearing gangue through both thermodynamic (by greatly reducing the surface energy of gangue through strong hydrophilicity) and kinetic (by inhibiting collector adsorption through steric barriers and high energy barriers). It not only overcomes the shortcomings of traditional small-molecule inhibitors, such as weak adsorption and easy desorption, but also compensates for the poor selectivity and susceptibility to mechanical entrainment of single polymer inhibitors. Thus, it achieves efficient, stable, and highly selective inhibition of calcium-bearing gangue minerals at the molecular recognition and interface engineering level, providing an innovative solution for the efficient separation of complex calcareous gangue-type cassiterite resources.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. This invention utilizes the synergistic combination of N-(phosphorylmethyl)glycine and carboxymethyl cellulose. N-(phosphorylmethyl)glycine acts as a "molecular anchoring agent," achieving precise identification and locking of calcium active sites on the surface of minerals such as calcite and fluorite through specific chelation. Carboxymethyl cellulose acts as a "spatial barrier and film-forming agent," forming a dense, hydrophilic, and stable three-dimensional coating film on the basis of anchoring, providing long-lasting three-dimensional shielding. The two complement each other and work synergistically to achieve high-intensity and high-selectivity inhibition of calcium-containing gangue without significantly affecting the floatability of cassiterite, thereby significantly improving the separation efficiency and concentrate quality of cassiterite and calcium-containing gangue minerals.

[0029] 2. The adsorption film formed by the combination inhibitors of this invention is stable and dense, overcoming the shortcomings of traditional single small molecule inhibitors that are easy to desorb and inorganic inhibitors that need to be added in excess. The inhibition effect is long-lasting and stable, which can effectively reduce the calcium impurity content in tin concentrate and improve the quality and sorting efficiency of tin concentrate.

[0030] 3. The combined inhibitor system in this invention greatly broadens the difference in floatability between cassiterite and calcium-containing gangue through the multi-level synergistic effect of "chemical anchoring-interface induction-three-dimensional physical shielding", achieving long-term stability of the inhibitory effect and effectively preventing the non-specific encapsulation of cassiterite by the agent.

[0031] 4. All components used in this invention are low-toxicity, easily biodegradable, and environmentally friendly agents. They pose no risk of heavy metal pollution, have excellent environmental compatibility, and meet the industrial development needs of green mineral processing.

[0032] 5. The combined inhibitor of this invention has strong adaptability and a wide applicable concentration range, which can be adapted to complex and varied cassiterite ore flotation systems. It has broad application prospects and can provide reliable technical support for the efficient recovery of complex calcareous gangue-type cassiterite resources. Attached Figure Description

[0033] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0034] Figure 1 This is a flowchart of the cassiterite flotation process in Embodiment 1 of the present invention;

[0035] Figure 2 This is a flowchart of the cassiterite flotation process of Comparative Example 1 of the present invention;

[0036] Figure 3 This is a flowchart of the cassiterite flotation process in Embodiment 2 of the present invention;

[0037] Figure 4 This is a flowchart of the cassiterite flotation process of Comparative Example 2 of the present invention;

[0038] Figure 5 This is a flowchart of the cassiterite flotation process in Embodiment 3 of the present invention;

[0039] Figure 6 This is a flowchart of the cassiterite flotation process of Comparative Example 3 of the present invention;

[0040] Figure 7 This is a flowchart of the cassiterite flotation process in Embodiment 4 of the present invention. Detailed Implementation

[0041] To make the technical means, inventive features, objectives and effects of the present invention easier to understand, the technical solution of the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0042] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] A cassiterite flotation inhibitor composed of N-(phosphorylmethyl)glycine and carboxymethyl cellulose.

[0044] Furthermore, the molecular formulas of the combined inhibitors are C(C(=O)O)NCP(=O)(O)O and (C6+2yH7+x+2yO2+x+3yNay)n;

[0045] The structural formula of the combined inhibitor is:

[0046] ,

[0047] Among them, N-(phosphorylmethyl)glycine is analytical grade, with a purity ≥95%, and is in powder form; carboxymethyl cellulose is type I, MW 700000 (DS=0.9), 2500~4500mPa.s;

[0048] The mass ratio of N-(phosphorylmethyl)glycine to carboxymethyl cellulose is 0.5–1.5:1.

[0049] Furthermore, the combined inhibitor is used in the flotation separation process of cassiterite and calcium-bearing minerals.

[0050] Specifically, the flotation includes one roughing, two to four sweeping, and two to three cleaning processes, with the combined inhibitor added during the roughing and cleaning processes.

[0051] More specifically, the amount of combined inhibitor added during the first coarse selection process is 200-400 g / t.

[0052] More specifically, the application includes the following steps:

[0053] (1) Prepare cassiterite slurry and adjust the pH of the slurry to 8-10;

[0054] (2) Add activator, inhibitor and collector to the slurry in sequence, and carry out roughing to obtain rough concentrate and rough tailings;

[0055] (3) Add a collector to the obtained coarse tailings and perform 2 to 4 scavenging operations to obtain scavenged concentrate. No frother is added in the last scavenging operation.

[0056] (4) Add inhibitors to the obtained crude concentrate and perform 2 to 3 fine selections to obtain tin concentrate.

[0057] More specifically, in the roughing process, the activator is lead acetate, and the addition amount is 50-100 g / t;

[0058] The amount of the combined inhibitor added is 200-400 g / t;

[0059] The collector is sodium oleate, and the addition amount is 800-1200 g / t.

[0060] More specifically, in the 2nd to 4th scavenging processes, the collector is sodium oleate. The amount of collector added in scavenging operation I is 400-600 g / t; the amount of collector added in scavenging operation II is 200-300 g / t; the amount of collector added in scavenging operation III is 100-150 g / t; and the amount of collector added in scavenging operation IV is 50-75 g / t.

[0061] More specifically, in the 2-3 selection processes, the amount of inhibitor added in selection process I is 100-200 g / t, the amount of inhibitor added in selection process II is 50-100 g / t, and the amount of inhibitor added in selection process III is 25-50 g / t.

[0062] More specifically, the combined inhibitor is added in the form of an aqueous solution with a mass percentage concentration of 0.5% to 1%;

[0063] The lead acetate is added in the form of an aqueous solution with a mass percentage concentration of 1-5%.

[0064] The sodium oleate is added in the form of an aqueous solution with a mass percentage concentration of 1-5%.

[0065] In summary, a more specific embodiment of the present invention is as follows:

[0066] The present invention will be further described in detail below with reference to specific embodiments and comparative examples, so as to provide reference and guidance for those skilled in the art. It should be noted that the embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention. All equivalent substitutions, improvements, etc. made based on the present invention should be included within the scope of protection of the present invention.

[0067] The reagents used in this invention are as follows: N-(phosphorylmethyl)glycine is analytical grade, with a purity ≥95%, and is in powder form; carboxymethyl cellulose is type I, with a molecular weight of 700,000, a degree of substitution DS=0.9, and a viscosity of 2500~4500 mPa·s; sodium oleate, lead acetate, and sodium hexametaphosphate are all analytical grade; the flotation machine used in the experiment is a 40mL hanging tank flotation machine with a fixed rotation speed of 1602r / min.

[0068] Example 1 (Application of combined inhibitors in the flotation of pure cassiterite)

[0069] In this Example 1, the SiO2 grade in the pure mineral system of cassiterite and calcium-bearing gangue (calcite / fluorite) is 30.32%, the MgO grade is 3.93%, and the Al2O3 grade is 5.98%.

[0070] This embodiment aims to verify the inhibitory effect of the combined inhibitor in a pure mineral system of cassiterite and calcium-bearing gangue (calcite / fluorite). The specific steps are as follows, and the flowchart is shown below. Figure 1 :

[0071] 1. Preparation of cassiterite slurry: Take 2g of mixed ore with a particle size of -74 to +38μm (cassiterite and calcite / fluorite in a mass ratio of 1:1), add 35mL of distilled water, and place them together in a 40mL hanging tank flotation machine. Turn on the stirring to adjust the slurry at a stirring speed of 1602r / min. After the slurry is adjusted, adjust the pH value of the slurry to 8~10;

[0072] 2. Reagent Addition and Flotation: First, a combined inhibitor (composed of N-(phosphorylmethyl)glycine and carboxymethyl cellulose) is added to the pulp, controlling the total concentration of the combined inhibitor in the pulp to be 20 mg / L. The mass ratio of N-(phosphorylmethyl)glycine to carboxymethyl cellulose is set to four gradients: 1.5, 1, 0.5, and 0.2. Then, sodium oleate collector is added, controlling its concentration to be 80 mg / L. After all reagents are added, aeration is carried out for flotation. After flotation, the froth product (tin concentrate) and the tailings in the flotation cell are collected separately.

[0073] 3. Index testing: The collected foam products and tailings are placed in an oven to dry, weighed after drying, and the yield and recovery rate of cassiterite are calculated based on the weighing results. At the same time, the tin grade in the foam products is tested.

[0074] The flotation results of pure minerals in this embodiment are shown in Table 1 below. As can be seen from the data in Table 1, the combined inhibitor of this invention has a significant effect on the flotation separation of cassiterite and calcite / fluorite, and the effect varies within different ratio ranges: when the concentration of the combined inhibitor is 20 mg / L and the mass ratio of N-(phosphorylmethyl)glycine to carboxymethyl cellulose is in the range of 0.5 to 1.5, the cassiterite grade can be stabilized above 73%, and the recovery rate can reach above 88.5%. Among them, the effect is best when the ratio is 1.5, with a cassiterite grade of 73.23% and a recovery rate as high as 89.78%; while when the ratio is reduced to 0.2, the inhibition effect decreases significantly, with a cassiterite grade of only 54.13% and a recovery rate of 72.10%, indicating that the optimal mass ratio range of the combined inhibitor of this invention is 0.5 to 1.5.

[0075]

[0076] Table 1

[0077] Comparative Example 1 (Application of a single inhibitor in the flotation of pure cassiterite, compared with Example 1)

[0078] This comparative example uses existing single inhibitors (carboxymethyl cellulose, sodium hexametaphosphate) and the same pure mineral flotation system as Example 1 to verify the difference in effectiveness between existing single inhibitors and the combined inhibitors of this invention. Specific steps are as follows (see flowchart). Figure 2 :

[0079] 1. Preparation of cassiterite slurry: The steps are exactly the same as in Example 1, that is, take 2g of mixed ore with a particle size of -74 to +38μm (cassiterite and calcite / dolomite in a mass ratio of 1:1), add 35mL of distilled water, place it in a 40mL hanging tank flotation machine, stir and adjust the slurry at a speed of 1602r / min, and adjust the pH value of the slurry to 8~10;

[0080] 2. Reagent addition and flotation: First, add a single inhibitor (carboxymethyl cellulose or sodium hexametaphosphate) to the pulp, controlling the inhibitor concentration in the pulp to 20 mg / L (consistent with the total concentration of combined inhibitors in Example 1); then add sodium oleate collector, controlling its concentration to 80 mg / L (consistent with Example 1); after all reagents have been added, aeration is carried out for flotation. After flotation, the froth product and tailings are collected separately.

[0081] 3. Index testing: The steps are exactly the same as in Example 1. The foam product and tailings are dried, weighed, and the cassiterite recovery rate and grade are calculated.

[0082] The flotation results of the pure minerals in this comparative example are shown in Table 2 below. As can be seen from the data in Table 2, the flotation effect of existing single inhibitors is far lower than that of the combined inhibitor of this invention: when the inhibitor concentration is 20 mg / L, with carboxymethyl cellulose as the inhibitor, the cassiterite grade is only 42.17%, and the recovery rate is 59.21%; with sodium hexametaphosphate as the inhibitor, the cassiterite grade is 56.89%, and the recovery rate is 68.91%, both significantly lower than the cassiterite grade (≥73%) and recovery rate (≥88.5%) of the combined inhibitor (ratio 0.5–1.5) in Example 1. This demonstrates that the combined inhibitor of this invention significantly improves the separation selectivity of cassiterite from calcium-containing gangue and the cassiterite recovery rate through synergistic effects.

[0083]

[0084] Table 2

[0085] Example 2 (Application of combined inhibitors in the flotation of raw cassiterite from a cassiterite mountain)

[0086] In this Example 2, actual industrial ore (raw tin ore) was used, with a SiO2 grade of 25.61%, a MgO grade of 1.98%, and an Al2O3 grade of 8.54%.

[0087] This embodiment uses actual industrial ore (raw cassiterite from a cassiterite mine) to verify the application effect of the combined depressant in an actual ore flotation system. The specific steps are as follows, and the flowchart is shown below. Figure 3 :

[0088] 1. Mineral sample preparation: Take raw ore from a cassiterite mountain (the feed ore contains 0.28% tin and 7.19% calcium), and grind it in a grinding mill until the mineral monomers are completely liberated, to obtain a slurry with 90% of the particles being -200 mesh; send the slurry to a flotation cell and adjust the pH value of the slurry to the range of 8 to 10.

[0089] 2. Roughing operation: Add 50 g / t of lead acetate, 120 g / t of N-(phosphorylmethyl)glycine, 80 g / t of carboxymethyl cellulose and 800 g / t of sodium oleate to the slurry in sequence; after all additions are completed, ventilate to carry out roughing operation. After roughing is completed, rough concentrate and rough tailings are obtained.

[0090] 3. Scavenging operation: Add 400g / t of sodium oleate to the rough tailings obtained from the roughing process, stir evenly, and then perform the first scavenging; collect the tailings from the first scavenging, add 200g / t of sodium oleate to them, stir evenly, and then perform the second scavenging; after the second scavenging is completed, the final flotation tailings are obtained; the middlings produced during the scavenging process are all returned to the previous stage of flotation operation to form a closed-circuit flotation.

[0091] 4. Cleaning Operation: Add 60 g / t of N-(phosphorylmethyl)glycine and 40 g / t of carboxymethyl cellulose to the rough concentrate obtained from the roughing process, stir evenly, and then perform the first cleaning operation; collect the concentrate from the first cleaning operation, add 30 g / t of N-(phosphorylmethyl)glycine and 20 g / t of carboxymethyl cellulose to it, stir evenly, and then perform the second cleaning operation; after the second cleaning operation, the final flotation concentrate is obtained; the middlings produced during the cleaning process are returned to the previous stage of flotation operation to form a closed-circuit flotation.

[0092] 5. Index testing: The final flotation concentrate and flotation tailings are dried and weighed separately, and the grade and recovery rate of tin concentrate are calculated. At the same time, the grade and recovery rate of calcium in tin concentrate are tested.

[0093] The experimental results show that, under the condition of a tin grade of 0.28% in the feed ore, after a closed-circuit flotation process consisting of one roughing, two cleaning, and two scavenging stages, a tin concentrate with a tin grade of 6.13% and a tin recovery rate of 87.16% can be obtained. At the same time, the calcium grade in the tin concentrate is only 0.77%, and the calcium recovery rate is 0.42%. This indicates that the combined inhibitor of the present invention can effectively inhibit calcium-bearing gangue in the ore, significantly improve the quality of the tin concentrate, and achieve efficient separation of cassiterite and calcium-bearing gangue.

[0094] Comparative Example 2 (Application of a single inhibitor in the flotation of raw cassiterite from a cassiterite mine, compared with Example 2)

[0095] This comparative example uses the same cassiterite ore from a certain cassiterite mine as in Example 2, and employs existing single inhibitors (N-(phosphorylmethyl)glycine alone and carboxymethyl cellulose alone) to verify the difference in industrial application effects between these and the combined inhibitors of this invention. The specific steps are as follows, and the flowchart is shown below. Figure 4 :

[0096] 1. Mineral sample preparation: The steps are exactly the same as in Example 2, namely grinding to 90% -200 mesh, dissociating mineral monomers, and adjusting the pH of the slurry to 8-10.

[0097] 2. Roughing operation: Add 50 g / t of lead acetate, 200 g / t of single inhibitor (N-(phosphorylmethyl)glycine or carboxymethyl cellulose) (total amount is the same as the total amount of combined inhibitor in Example 2), and 800 g / t of sodium oleate to the slurry in sequence; after all additions are completed, aeration is carried out for roughing to obtain rough concentrate and rough tailings.

[0098] 3. Scavenging operation: The steps are exactly the same as in Example 2, that is, the coarse tailings are scavenged twice to obtain flotation tailings, and the scavenged ore is returned to the previous operation.

[0099] 4. Cleaning process: Add 100g / t of the corresponding single inhibitor (N-(phosphorylmethyl)glycine / carboxymethyl cellulose) to the rough concentrate for the first cleaning; add 50g / t of the corresponding single inhibitor to the first cleaned concentrate for the second cleaning; return the middlings from the cleaned process to the previous stage to obtain the final flotation concentrate.

[0100] 5. Index detection: The steps are exactly the same as in Example 2, and the grade and recovery rate of tin concentrate, as well as the grade and recovery rate of calcium, are detected.

[0101] The experimental results show that, under the same feed conditions and flotation process, the flotation effect of a single inhibitor is far lower than that of the combined inhibitor of the present invention: when only N-(phosphorylmethyl)glycine is used, the tin grade of the obtained tin concentrate is 2.13%, the tin recovery rate is 49.39%, the calcium grade is 3.67%, and the calcium recovery rate is 3.31%; when only carboxymethyl cellulose is used, the tin grade of the obtained tin concentrate is 3.81%, the tin recovery rate is 45.56%, the calcium grade is 4.13%, and the calcium recovery rate is 1.92%. Compared with Example 2, the tin concentrate grade is increased by more than 2 times, the tin recovery rate is increased by more than 38 percentage points, and the calcium grade and calcium recovery rate are significantly reduced, further proving the synergistic effect of the combined inhibitor of the present invention, whose inhibition effect and separation efficiency are far superior to those of a single inhibitor.

[0102] Example 3 (Application of combined inhibitors in the flotation of raw cassiterite from a cassiterite mountain)

[0103] In this Example 3, the SiO2 grade of the actual industrial ore from another production area (a certain tin mine raw ore) is 35.59%, the MgO grade is 5.17%, and the Al2O3 grade is 5.36%.

[0104] This embodiment uses actual industrial ore from another production site (raw cassiterite from a certain cassiterite mountain) to further verify the applicability and stability of the combined inhibitor. The specific steps are as follows, and the flowchart is shown below. Figure 5 :

[0105] 1. Mineral sample preparation: Take raw ore from a cassiterite mountain (the ore contains 0.32% tin and 7.34% calcium), feed it into a grinding mill for grinding, and grind until the mineral monomers are completely liberated to obtain a slurry with 90% -200 mesh; adjust the pH of the slurry to the range of 8 to 10.

[0106] 2. Roughing operation: Add 75g / t of lead acetate, 150g / t of N-(phosphorylmethyl)glycine, 150g / t of carboxymethyl cellulose and 1000g / t of sodium oleate to the slurry in sequence; after all additions are completed, ventilate for roughing to obtain rough concentrate and rough tailings.

[0107] 3. Scavenging operation: Add 500g / t of sodium oleate to the coarse tailings for the first scavenging; add 250g / t of sodium oleate to the tailings from the first scavenging for the second scavenging; the final flotation tailings are obtained, and the scavenged ore is returned to the previous operation to form a closed loop.

[0108] 4. Fine Concentration Process: Add 75 g / t of N-(phosphorylmethyl)glycine and 75 g / t of carboxymethyl cellulose to the rough concentrate for the first fine concentration; add 37.5 g / t of N-(phosphorylmethyl)glycine and 37.5 g / t of carboxymethyl cellulose to the first fine concentrate for the second fine concentration; the final flotation concentrate is obtained, and the middlings are returned to the previous stage of the process to form a closed loop.

[0109] 5. Index testing: Dry and weigh the flotation concentrate and tailings, and calculate the tin concentrate grade and recovery rate.

[0110] The experimental results show that, under the condition of a tin grade of 0.32% in the feed ore, after a closed-circuit flotation process consisting of one roughing, two cleaning, and two scavenging stages, a tin concentrate with a tin grade of 6.67% and a tin recovery rate of 82.36% can be obtained. At the same time, the calcium grade in the tin concentrate is only 0.68%, and the calcium recovery rate is 0.36%. This indicates that the combined inhibitor of the present invention is suitable for cassiterite ores from different origins and with different compositions, and has good applicability and stability, and can effectively achieve efficient separation of cassiterite and calcium-bearing gangue.

[0111] Comparative Example 3 (Application of existing inorganic inhibitors in the flotation of raw cassiterite from a cassiterite mine, compared with Example 3)

[0112] This comparative example uses the same cassiterite ore from a certain cassiterite mine as in Example 3, and employs a commonly used inorganic inhibitor (sodium hexametaphosphate) to verify the difference in effectiveness between it and the combined inhibitor of the present invention. The specific steps are as follows, and the flowchart is shown below. Figure 6 :

[0113] 1. Mineral sample preparation: The steps are exactly the same as in Example 3, namely grinding to 90% -200 mesh, dissociating mineral monomers, and adjusting the pH of the slurry to 8-10.

[0114] 2. Roughing operation: Add 75 g / t of lead acetate, 300 g / t of sodium hexametaphosphate (the dosage is the same as the total dosage of the combined inhibitor in Example 3), and 1000 g / t of sodium oleate to the slurry in sequence; after all the additions are completed, ventilate for roughing to obtain rough concentrate and rough tailings.

[0115] 3. Scavenging operation: Add 500g / t of sodium oleate to the coarse tailings, stir for 3 minutes and then carry out the first scavenging; add 250g / t of sodium oleate to the tailings from the first scavenging and carry out the second scavenging; obtain the final flotation tailings, and return the scavenged ore to the previous stage operation.

[0116] 4. Fine Concentration Process: Add 150 g / t of sodium hexametaphosphate to the rough concentrate for the first fine concentration; add 75 g / t of sodium hexametaphosphate to the first fine concentrate for the second fine concentration; the final flotation concentrate is obtained, and the middlings are returned to the previous stage of the process.

[0117] 5. Index detection: The steps are exactly the same as in Example 3, and the tin concentrate grade, recovery rate, calcium grade, and calcium recovery rate are detected.

[0118] The experimental results show that, under the same feed conditions and flotation process, the inhibition effect of sodium hexametaphosphate is far lower than that of the combined inhibitor of the present invention: the tin concentrate obtained has a tin grade of only 3.14% and a tin recovery rate of 49.18%, while the calcium grade in the tin concentrate is as high as 4.13% and the calcium recovery rate is 2.82%. Compared with Example 3, the tin concentrate grade is increased by more than 112%, the tin recovery rate is increased by more than 33 percentage points, and the calcium impurity content is significantly reduced, proving that the combined inhibitor of the present invention has stronger inhibition efficacy and higher selectivity than commonly used inorganic inhibitors.

[0119] Example 4 (Application of combined inhibitors in the flotation of a high-tin grade ore)

[0120] This embodiment uses high-tin-grade cassiterite ore from a certain region to verify the application effect and compatibility of the combined inhibitor in high-tin-grade ore. The specific steps are as follows, and the flowchart is shown below. Figure 7 :

[0121] 1. Mineral sample preparation: Take raw tin ore from a certain cassiterite mountain (the ore contains 0.45% tin and 7.27% calcium) and grind it in a grinding mill until the mineral monomers are completely liberated, and obtain a slurry with 90% -200 mesh; adjust the pH of the slurry to the range of 8 to 10.

[0122] 2. Roughing operation: Add 100g / t of lead acetate, 100g / t of N-(phosphorylmethyl)glycine, 200g / t of carboxymethyl cellulose and 1200g / t of sodium oleate to the slurry in sequence; after all reagents have been added, ventilate for roughing to obtain rough concentrate and rough tailings.

[0123] 3. Scavenging operation: Add 600 g / t of sodium oleate to the coarse tailings for the first scavenging; add 300 g / t of sodium oleate to the tailings from the first scavenging for the second scavenging; add 150 g / t of sodium oleate to the tailings from the second scavenging for the third scavenging; the final flotation tailings are obtained. The middlings produced during the scavenging process are returned to the previous flotation operation to form a closed loop.

[0124] 4. Cleaning Operation: Add 50 g / t of N-(phosphorylmethyl)glycine and 100 g / t of carboxymethyl cellulose to the rough concentrate for the first cleaning; add 25 g / t of N-(phosphorylmethyl)glycine and 50 g / t of carboxymethyl cellulose to the first clean concentrate for the second cleaning; add 12.5 g / t of N-(phosphorylmethyl)glycine and 25 g / t of carboxymethyl cellulose to the second clean concentrate for the third cleaning; the final flotation concentrate is obtained. The middlings produced during the cleaning process are returned to the previous flotation operation, forming a closed loop.

[0125] 5. Index testing: Dry and weigh the final flotation concentrate and tailings, and calculate the tin concentrate grade and recovery rate.

[0126] The experimental results show that, under the condition of a tin grade of 0.45% in the feed ore, after a closed-circuit flotation process consisting of one roughing, three cleaning, and three scavenging stages, a tin concentrate with a tin grade of 6.39% and a tin recovery rate of 83.49% can be obtained. At the same time, the calcium grade in the tin concentrate is as high as 0.65%, with a calcium recovery rate of 0.52%. This indicates that the combined inhibitor of the present invention is suitable for high-tin-grade cassiterite ore. By optimizing the flotation process and reagent dosage, it can effectively inhibit calcium-containing gangue, achieving efficient recovery and purification of cassiterite. This further verifies the wide applicability and excellent inhibition effect of the combined inhibitor of the present invention.

[0127] Comprehensive test conclusions

[0128] Based on the experimental results of Examples 1-4 and Comparative Examples 1-3 above, it can be seen that the present invention uses N-(phosphorylmethyl)glycine and carboxymethyl cellulose to form a combined inhibitor. Through the three-in-one synergistic mechanism of "molecular anchoring-stereoscopic film formation-synergistic stabilization", the inhibitory ability and selectivity of calcium gangue minerals such as calcite and fluorite are significantly better than existing single inhibitors (carboxymethyl cellulose and N-(phosphorylmethyl)glycine used alone) and commonly used inorganic inhibitors (sodium hexametaphosphate).

[0129] This combined inhibitor not only achieves efficient separation of cassiterite and calcium-bearing gangue in pure mineral systems, but is also adaptable to actual industrial cassiterite ores from different origins and with different tin grades. Through reasonable flotation processes and reagent dosages, it can stabilize the tin concentrate grade at over 6% and the tin recovery rate at over 82%, while significantly reducing the calcium impurity content in the tin concentrate. It solves the technical problems of poor selectivity, insufficient inhibition efficiency, and poor environmental compatibility of existing inhibitors, providing reliable technical support for the efficient recovery of complex calcium-bearing gangue cassiterite resources and has broad prospects for industrial application.

[0130] During use, this cassiterite flotation inhibitor achieves synergistic effects through clear molecular division of labor and multi-level synergy: N-(phosphonomethyl)glycine, as a molecular recognition unit, with its rigid "bifunctional pincer" structure (phosphonic acid group and carboxyl group), can selectively chelate with Ca²⁺ on the surface of calcium gangue, achieving precise chemical anchoring and blocking the collector's action site at the source. Carboxymethyl cellulose, as a spatial barrier unit, can spread its long polymer chains at the interface through physical adsorption, forming a dense, hydrophilic three-dimensional protective film. This film physically isolates the collector through a strong steric hindrance effect and significantly strengthens the surface hydration layer. The synergistic mechanism between the two lies in the fact that the specific chemical adsorption of small molecules provides an optimized binding interface for polymers, inducing their directional and stable enrichment; the polymer film weaves the dispersed chemical anchoring points into a continuous and complete protective network, which not only enhances the persistence and coverage of inhibition but also prevents non-specific encapsulation of cassiterite. This multi-level synergistic effect of "specific chemical anchoring-interface induction-three-dimensional physical shielding" significantly expands the difference in floatability from the dual dimensions of chemical bonding and physical barrier, achieving efficient, highly selective and environmentally friendly inhibition, and providing a breakthrough solution for improving the quality and reducing the calcium content of complex cassiterite resources.

[0131] Finally, it should be noted that the concept, specific structure, and technical effects of the present invention have been clearly and completely described above in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections and connection relationships mentioned herein do not simply refer to direct connection of components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

Claims

1. A cassiterite flotation depressant, characterized in that: This combination inhibitor consists of N-(phosphorylmethyl)glycine and carboxymethyl cellulose.

2. The cassiterite flotation combination inhibitor according to claim 1, characterized in that: The N-(phosphorylmethyl)glycine is analytical grade, with a purity ≥95%, and is in powder form; the carboxymethyl cellulose is type I, MW 700000 (DS=0.9), 2500~4500mPa.s; The mass ratio of N-(phosphorylmethyl)glycine to carboxymethyl cellulose is 0.5–1.5:

1.

3. The application of the cassiterite flotation combination inhibitor as described in claim 1 or 2, characterized in that: The combined inhibitors were used in the flotation separation process of cassiterite and calcium-bearing minerals.

4. The application of the cassiterite flotation combination inhibitor according to claim 3, characterized in that: The flotation process includes one roughing, two to four scavenging, and two to three cleaning processes, with the combined inhibitor added during the roughing and cleaning processes.

5. The application of the cassiterite flotation combination inhibitor according to claim 4, characterized in that: The amount of combined inhibitor added during the first coarse selection process is 200-400 g / t.

6. The application of the cassiterite flotation combination inhibitor according to claim 3, characterized in that: The application includes the following steps: (1) Prepare cassiterite slurry and adjust the pH of the slurry to 8-10; (2) Add activator, inhibitor and collector to the slurry in sequence, and carry out roughing to obtain rough concentrate and rough tailings; (3) Add a collector to the obtained coarse tailings and perform 2 to 4 scavenging operations to obtain scavenged concentrate. No frother is added in the last scavenging operation. (4) Add inhibitors to the obtained crude concentrate and perform 2 to 3 fine selections to obtain tin concentrate.

7. The application of the cassiterite flotation combination inhibitor according to claim 6, characterized in that: In the roughing process, the activator is lead acetate, and the addition amount is 50-100 g / t; The amount of the combined inhibitor added is 200-400 g / t; The collector is sodium oleate, and the addition amount is 800-1200 g / t.

8. The application of the cassiterite flotation combination inhibitor according to claim 6, characterized in that: In the 2nd to 4th scavenging processes, the collector is sodium oleate. The amount of collector added in scavenging operation I is 400-600 g / t; the amount of collector added in scavenging operation II is 200-300 g / t; the amount of collector added in scavenging operation III is 100-150 g / t; and the amount of collector added in scavenging operation IV is 50-75 g / t.

9. The application of the cassiterite flotation combination inhibitor according to claim 6, characterized in that: In the 2nd to 3rd selection processes, the amount of inhibitor added in selection process I is 100 to 200 g / t, the amount of inhibitor added in selection process II is 50 to 100 g / t, and the amount of inhibitor added in selection process III is 25 to 50 g / t.

10. The application of the cassiterite flotation combination inhibitor according to claim 7, characterized in that: The combined inhibitors are added in the form of an aqueous solution with a mass percentage concentration of 0.5% to 1%; The lead acetate is added in the form of an aqueous solution with a mass percentage concentration of 1-5%. The sodium oleate is added in the form of an aqueous solution with a mass percentage concentration of 1-5%.

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