Collophanite dealumination reverse flotation composite collecting agent and preparation method and application thereof

Abstract

The invention provides a collophanite dealumination reverse flotation composite collecting agent and a preparation method and application thereof.The composite collecting agent comprises, by mass, 45%-55% of benzalkonium chloride, 20%-30% of cocamidopropyl hydroxysulfobetaine, 15%-30% of iso-tridecanol polyoxyethylene ether and 3%-10% of sodium citrate. The collecting agent provided by the invention is green and environment-friendly, and solvent pollution can be thoroughly eliminated; the dealumination selectivity is high, and the content of Al2O3 in the concentrate is stable and less than or equal to 2.0 The process adaptability is high, and efficient flotation within the wide temperature range of 10-40 DEG C is achieved; the foam property is optimized, the half-life period of the foam is kept at 100-120 seconds, and the water content of the foam product is reduced to 35-38%.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, specifically relating to a composite collector for the reverse flotation dealuminization (Al2O3) process of medium- and low-grade phosphate rock, achieving efficient removal of aluminum impurities and enrichment of phosphate. Background Technology

[0002] Colophane accounts for over 75% of global phosphate rock resources, but high-grade deposits (P2O5 ≥ 30%) have shrunk dramatically due to long-term mining. Medium- and low-grade deposits (P2O5 content 15-25%) have become the mainstream resource, with the core challenge being the severe co-occurrence of aluminum, magnesium, and iron impurities. Taking the Yunnan-Guizhou mining area in China as an example, the "China Mineral Resources Report 2023" points out that the average P2O5 grade of colophane is only 22.5-24.8%, while the Al2O3 content is as high as 4.2-7.5%. Aluminum impurities in wet-process phosphoric acid production can form colloidal aluminum fluoride complexes, leading to a 30-fold increase in phosphoric acid viscosity, an 85% decrease in filtration rate, and equipment corrosion (literature). Industrial&Engineering Chemistry Research (2022). Currently, industrial mineral processing is dominated by flotation. Among them, reverse flotation dealuminization is widely used because of its simple process, low energy consumption (20-30% more energy saving than direct flotation), and suitability for fine-grained disseminated ores (more than 85% of which are -200 mesh). However, this process requires the collector to achieve high-precision separation of aluminum minerals and apatite under acidic conditions (pH 4-6), and the Al2O3 in the concentrate must be ≤2.0% to meet the standards for wet-process phosphoric acid production. Traditional collector systems are difficult to consistently meet these standards.

[0003] For acidic dealumination environments with pH 4-6, collector research focuses on three types of systems: anionic, cationic, and composite. Anionic systems, represented by sodium methyl ester sulfonate (MES) and petroleum sulfonates, rely on the electrostatic adsorption of sulfonic acid groups (-SO3⁻) and protonated aluminum minerals (Al-OH2⁺). However, sulfonates readily combine with Ca²⁺ on the surface of apatite in acidic slurries, resulting in a phosphorus loss rate of 15-20% (Example 2 of patent CN113292398A). Cationic systems are mainly composed of ether amines (such as C13 amine ethers) and quaternary ammonium salts, which adsorb negatively charged aluminum minerals through cationic groups (-NH3⁺ / -N⁺R4) (ζ potential < -20 mV at pH 4-6). However, amines require isopropanol / methanol as a solubilizer (addition amount 20-30%), resulting in VOC emissions > 200 ppm (exceeding the limit of HJ 1031-2019), and the recovery rate for fine-grained aluminum minerals (-20 μm) is only 60-68% (Minerals). Engineering, 2023, Vol. 192); Composite systems such as dodecylamine + oxidized paraffin soap (patent CN111036398B) improve selectivity, but have drawbacks such as foam viscosity (moisture content > 45%), low-temperature precipitation (solidification < 25℃) and the need to use sodium silicate inhibitor (cost + 35%).

[0004] The common defects exposed by the aforementioned existing technologies include: 1. Safety and environmental risks posed by alcohol solvents; 2. Insufficient selectivity in the separation of aluminum minerals and apatite, resulting in excessive aluminum content in the concentrate; 3. High foam viscosity leading to phosphorus entrainment loss; and 4. Poor low-temperature adaptability. Therefore, there is an urgent need to develop an alcohol-free, highly selective, low-temperature self-emulsifying collector to overcome the limitations of traditional processes. Summary of the Invention

[0005] To address the above problems, this invention provides a composite collector for dealuminization and reverse flotation of phosphate rock, comprising the following components by mass fraction: 45-55% benzalkonium chloride, 20-30% cocamidopropyl hydroxysulfonate betaine, 15-30% isotridecyl alcohol polyoxyethylene ether, and 3-10% sodium citrate.

[0006] Furthermore, the benzalkonium chloride has an alkyl chain of C12-C14, and preferably is a compound of benzalkonium chloride with an alkyl chain of C12 and benzalkonium chloride with an alkyl chain of C14 in a mass ratio of 1:(1-1.5).

[0007] Furthermore, the degree of polymerization of the isomeric tridecyl alcohol polyoxyethylene ether is 7-9.

[0008] This invention also provides a method for preparing a composite collector for dealuminization reverse flotation of phosphate rock, comprising the following steps: S1. Benzalkonium chloride and cocamidopropyl hydroxysulfonate betaine are heated and stirred at 80±5℃ under nitrogen protection to obtain mixture A; S2. Cool mixture A to 45-50℃, add isomeric tridecyl alcohol polyoxyethylene ether, and shear emulsify to obtain emulsion B; S3. Cool the emulsion to 35-40℃, add sodium citrate and stir to obtain emulsion C; S4. Cool the emulsion C to 25±5℃, add citric acid to adjust the pH to 6-6.5, and obtain the composite collector.

[0009] Furthermore, the nitrogen flow rate in S1 is 0.8-1.2 L / min; The cooling rate of S2 is 2-3℃ / min, the shear rate is 400-800rpm, and the shearing time is 5-15min; The cooling rate of S3 is 2-3℃ / min, the stirring rate is 100-500rpm, and the stirring time is 2-8min.

[0010] Furthermore, the sodium citrate has a particle size of <200 mesh.

[0011] The composite collector described in this invention or the composite collector obtained by the preparation method described herein is used for reverse flotation dealuminization of phosphate rock.

[0012] Furthermore, it includes the following steps: (1) Grind the phosphate rock to -200 mesh ≥65%, add water to adjust the slurry concentration to 25-30%, and adjust the pH to 4.5-5.5 with sulfuric acid; (2) Add 0.3-1.0 kg / t of collector to the ore and stir for 1-5 min; (3) Aeration flotation for 5-8 minutes, aeration volume of 0.3-1.0 m³. 3 / (m 2 ·min), to obtain refined phosphate rock.

[0013] Furthermore, the collophane is low-grade or medium-grade collophane.

[0014] Furthermore, the reverse flotation dealuminization temperature is 10-40℃.

[0015] The beneficial effects of this invention are as follows: (1) Green and environmentally friendly, completely eliminating solvent pollution: Alcohol-free self-emulsification is achieved by compounding cocamidopropyl hydroxysulfonate with isotridecyl alcohol polyoxyethylene ether. The HLB value of the compounding system is controlled at 12.5-13.0, forming a stable oil-in-water emulsion. The use of toxic solvents such as methanol and isooctanol in traditional formulations is completely avoided, achieving zero VOCs (volatile organic compounds) emissions. The COD value of flotation wastewater can be reduced from >5000 mg / L in traditional schemes to below 100 mg / L.

[0016] (2) High selectivity for dealumination and breakthrough in dealumination efficiency: A dual inhibition mechanism of "chemical chelation-physical steric hindrance" is formed by sodium citrate and isomeric tridecyl alcohol polyoxyethylene ether to control the reaction between sodium citrate and Ca on the surface of apatite. 2+ The chelation reaction is preferential to benzalkonium chloride adsorption, which precisely and efficiently inhibits the flotation of apatite, and expands the difference in floatability (contact angle difference) between aluminum minerals and apatite to more than 30°. This solves the problem of poor selectivity of traditional reagents leading to substandard concentrate grade, improves the separation accuracy of aluminum / phosphorus minerals, and keeps the Al2O3 content in the concentrate stable at ≤2.0%.

[0017] The basic principle of the dual inhibition mechanism of "chemical chelation-physical steric hindrance" formed by sodium citrate and isomeric tridecyl alcohol polyoxyethylene ether is as follows: (a) Sodium citrate (molecular weight ~258) has a smaller molecular size and faster diffusion rate than benzalkonium chloride (such as BAC-12, molecular weight ~340) and the micelles formed therefrom, which allows it to reach the mineral surface earlier and faster. (b) Citrate ions inhibit Ca 2+ The chelation constant is extremely high (forming a complex with a stability constant logK>3), which is a strong, rapid, and specific chemical reaction; while the adsorption of cationic collectors on the apatite surface is mainly due to electrostatic interactions, which are relatively weak under acidic conditions. Therefore, from the perspective of reaction kinetics and thermodynamics, the chelation reaction is more advantageous. (c) Nonionic C13EO adsorbs onto the apatite surface through hydrogen bonding via its polyoxyethylene chains, and simultaneously forms steric hindrance through its long chains. Together with sodium citrate, it constructs a dense "composite hydrophilic protective film" on the apatite surface. This physical barrier further hinders the adsorption of collector molecules.

[0018] (3) Strong process adaptability, achieving low-temperature and high-efficiency flotation: The collector provided by this invention has no precipitation or stratification after 30 days of storage at 25℃; within a wide temperature range of 10-40℃, the collector provided by this invention has a dispersion time of less than 10 seconds in the slurry, overcoming the disadvantages of traditional amine collectors that are easy to solidify and slow to disperse at low temperatures, and no additional heating of the slurry is required during use.

[0019] (4) Optimization of foam properties and reduction of effective ingredient loss: The foam stability is controlled by the zwitterionic properties of cocamidopropyl hydroxysulfonate betaine, so that the foam half-life is maintained at 100-120 seconds; the foam formed has good fluidity, is brittle and non-sticky, and the water content of the foam product can be reduced from 45%-50% in the traditional scheme to 35%-38%, which greatly reduces the mechanical entrainment loss of fine-grained apatite concentrate, and at the same time reduces the energy consumption and cost of subsequent dehydration processes. Detailed Implementation

[0020] The embodiments of the present invention will be described in detail below with reference to the examples. The following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0021] Example 1 S1, Preparation of Phosphate Rock Collector S1-1. Add 50 parts of benzalkonium chloride (alkyl chain C12) and 25 parts of cocamidopropyl hydroxysulfonate to a nitrogen-protected reactor and stir. The nitrogen flow rate in the reactor is 1 L / min, the temperature is 82℃, the stirring speed is 400 rpm, and the stirring time is 15 minutes to obtain mixture A.

[0022] S1-2. Cool mixture A to 48°C, add 20 parts of isomeric tridecyl alcohol polyoxyethylene ether with a degree of polymerization of 8 and stir to emulsify at a stirring speed of 600 rpm for 10 min to obtain emulsion B.

[0023] S1-3. Cool emulsion B to 40℃ (cooling rate is 3℃ / min), add 5 parts of sodium citrate powder (particle size <200 mesh) and stir at 300 rpm for 5 minutes.

[0024] S1-4. After stirring, cool to 25℃ (cooling rate is 3℃ / min), add citric acid to adjust pH=6.5, and obtain a water-in-oil emulsion aluminum-removing collector with a solid content of 40%.

[0025] The collector concentration was adjusted to 1% (working concentration), and the half-life of the collector foam was measured to be 103 s by the bubbling method.

[0026] S2, reverse flotation of collophane ore S2-1. Take Hubei siliceous calcium phosphate rock type collophane ore (main components include P2O5 25.75%, MgO 1.36%, Al2O3 4.41%), crush it and then grind it, control the grinding fineness to -0.074mm accounting for 70.4%, and add water to adjust the slurry concentration to 27%.

[0027] Under S2-2 and 10℃ conditions, sulfuric acid was added to the slurry to adjust the pH of the slurry to 5.5. After stirring for 3 min, 0.3 kg / t (based on the dry weight of phosphate rock) of the dealuminizing collector prepared in S1 was added and stirred for 3 min to obtain a mixed slurry. S2-3. Aerate and skim the mixed slurry for 5 minutes, with an aeration rate of 0.8 m³ / s. 3 / (m 2 The foam product obtained is tailings, and the product in the tank is phosphate concentrate.

[0028] Tests showed that the phosphate concentrate had a P2O5 content of 31.81%, MgO content of 1.13%, and Al2O3 content of 1.76%, with a concentrate recovery rate of 65.95% and good concentrate separation properties.

[0029] The contact angle measuring instrument measured the contact angle between the collector and the aluminum mineral to be 52°, and the contact angle between the collector and the apatite to be 19°. The moisture content of the foam product was measured to be 37% after filtration and drying. The lower moisture content can effectively reduce transportation and dehydration costs and increase the production capacity of the beneficiation plant equipment.

[0030] Comparative Example 1 Unlike Example 1, operations S1-3 are omitted; the rest is the same as in Example 1.

[0031] Tests showed that the phosphate concentrate had a P2O5 content of 31.37%, MgO content of 1.28%, and Al2O3 content of 1.89%, with a concentrate recovery rate of 59.28%. The concentrate had good separation properties, but the phosphate concentrate recovery was poor.

[0032] The half-life of the collector foam was determined to be 107 s by the blasting method; the contact angle between the collector and aluminum minerals was 55° and the contact angle between the collector and apatite was 31°; the moisture content of the foam product was determined to be 43% after filtration and drying.

[0033] The results of Example 1 and Comparative Example 1 show that, in the preparation of the phosphate rock dealuminizing collector, the absence of sodium citrate has little impact on the P2O5 grade and impurities MgO and Al2O3 of the phosphate concentrate obtained from the reverse flotation of siliceous calcium phosphate rock, but the phosphate concentrate recovery rate decreases significantly. Therefore, adding sodium citrate to the phosphate rock dealuminizing collector can effectively reduce phosphate concentrate loss and improve the phosphate resource recovery rate. The core value of sodium citrate lies in its chelating effect, which shields the calcium active sites on the surface of apatite, thereby blocking the adsorption of cationic collectors and synergistically achieving efficient separation of aluminum minerals and apatite with the collector.

[0034] Comparative Example 2 Unlike Example 1, in S1-1, benzalkonium chloride was adjusted to 40 parts and cocamidopropyl hydroxysulfonate was adjusted to 35 parts, while the rest were the same as in Example 1.

[0035] Tests showed that the phosphate concentrate contained 30.01% P2O5, 1.19% MgO, and 2.12% Al2O3, with a concentrate recovery rate of 68.86%. The concentrate had poor separation properties and exceeded the aluminum content standard.

[0036] The half-life of the collector foam was determined to be 93 s using the blasting method. The contact angle between the collector and aluminum minerals was measured to be 36°, and the contact angle between the collector and apatite was measured to be 17°. The moisture content of the foam product was measured to be 31% after filtration and drying.

[0037] The results of Example 1 and Comparative Example 2 show that when benzalkonium chloride is used as the main collector for dealuminizing phosphate rock, it electrostatically adsorbs aluminum minerals. However, when its content is low, it cannot efficiently remove aluminum impurities, resulting in substandard concentrate grade.

[0038] Comparative Example 3 Unlike Example 1, in S1-1, benzalkonium chloride was adjusted to 60 parts and cocamidopropyl hydroxysulfonate was adjusted to 15 parts, while the rest were the same as in Example 1.

[0039] Tests showed that the phosphate concentrate had a P2O5 content of 29.37%, an MgO content of 1.28%, an Al2O3 content of 1.27%, and a concentrate recovery rate of 50.76%. The concentrate grade was substandard, the recovery was poor, and the foam was sticky and had poor fluidity.

[0040] The half-life of the collector foam was determined to be 178 s using the blasting method. The contact angle between the collector and the aluminum mineral was measured to be 62°, and the contact angle between the collector and the apatite was measured to be 39°. The moisture content of the foam product was measured to be 31% after filtration and drying.

[0041] The results of Example 1 and Comparative Example 3 indicate that when benzalkonium chloride is used as the primary collector, excessively high concentrations lead to a large amount of apatite being collected and floated to the surface, significantly reducing the P2O5 grade and recovery rate of the concentrate in the tank. Furthermore, the increased foaming properties result in overly stable foam that is difficult to break and transport.

[0042] Example 2 Unlike Example 1, in S2 the phosphate rock was changed to a spiral sluice gravity separation tailings of a siliceous calcium phosphate rock type collophane mine in Hubei (-200 mesh accounted for 95%, and the main components included P2O5 22.31%, MgO 1.94%, and Al2O3 4.54%), and the rest was the same as in Example 1.

[0043] Tests showed that the phosphate concentrate had a P2O5 content of 30.32%, an Al2O3 content of 1.89%, a concentrate recovery rate of 43.54%, and good concentrate separation properties.

[0044] The contact angle measuring instrument measured the contact angle between the collector and the aluminum mineral to be 50°, and the contact angle between the collector and the apatite to be 21°; the moisture content of the foam product was measured to be 41% after filtration and drying.

[0045] The results show that the dealuminizing collector provided by the present invention still has a good separation effect on the reverse flotation dealuminization of fine-grained (more than 90% of -200 mesh) phosphate rock.

[0046] Example 3 The only difference from Example 1 is that S2-1 is different. Specifically, S2-1 is as follows: take Hubei siliceous calcium phosphate rock type collophane (main components include P2O5 17.67%, MgO 1.68%, Al2O3 6.75%), crush it and then grind it, control the grinding fineness to -0.074mm accounting for 70.4%, and add water to adjust the slurry concentration to 20%.

[0047] Tests showed that the phosphate concentrate had a P2O5 content of 29.52%, an Al2O3 content of 1.95%, a concentrate recovery rate of 43.23%, and good concentrate separation properties.

[0048] The contact angle measuring instrument measured the contact angle between the collector and the aluminum mineral to be 57°, and the contact angle between the collector and the apatite to be 23°; the moisture content of the foam product was measured to be 39% after filtration and drying.

[0049] The results show that the dealuminizing collector provided by this invention still has a good separation effect on the reverse flotation dealuminization operation of low-grade phosphate rock.

[0050] Example 4 Unlike Example 1, benzalkonium chloride was obtained by compounding benzalkonium chloride with an alkyl chain of C12 and benzalkonium chloride with an alkyl chain of C14 in a mass ratio of 1:1. The rest is the same as in Example 1.

[0051] Tests showed that the phosphate concentrate had a P2O5 content of 32.67%, MgO content of 1.15%, and Al2O3 content of 1.52%, with a concentrate recovery rate of 70.95% and good concentrate separation properties.

[0052] The half-life of the collector foam was determined to be 100 s using the blasting method. The contact angle between the collector and the aluminum mineral was measured to be 57°, and the contact angle between the collector and the apatite was measured to be 22°. The moisture content of the foam product was measured to be 34% after filtration and drying.

[0053] The results showed that the combination of benzalkonium chloride C12 and C14 as the main collector achieved the best collecting performance. The foam structure was optimal, resulting in the best overall performance.

[0054] Example 5 The difference from Example 1 is that the reverse flotation temperature is 40°C, while the rest is the same as in Example 1.

[0055] Tests showed that the phosphate concentrate had a P2O5 content of 31.74%, MgO content of 1.11%, and Al2O3 content of 1.81%, with a concentrate recovery rate of 65.03% and good concentrate separation properties.

[0056] The contact angle measuring instrument measured the contact angle between the collector and the aluminum mineral to be 49°, and the contact angle between the collector and the apatite to be 20°; the moisture content of the foam product was measured to be 32% after filtration and drying.

[0057] The results show that the dealuminizing collector provided by the present invention has a wide applicable temperature range, is not limited by season or region, and can effectively reduce energy consumption in beneficiation plants and save production costs.

[0058] Comparative Example 4 The difference from Example 1 is that benzalkonium chloride is replaced with dodecyltrimethylammonium bromide, otherwise the same as in Example 1.

[0059] Tests showed that the phosphate concentrate had a P2O5 content of 29.89%, an MgO content of 1.23%, and an Al2O3 content of 2.21%, with a concentrate recovery rate of 56.93%. The concentrate was of poor quality, with excessive aluminum content and poor recovery. The foam was sticky and difficult to dissipate.

[0060] The half-life of the collector foam was determined to be 183 s using the blasting method. The contact angle between the collector and the aluminum mineral was measured to be 53°, and the contact angle between the collector and the apatite was measured to be 37°. The moisture content of the foam product was measured to be 41% after filtration and drying.

[0061] The results of Example 1 and Comparative Example 4 show that benzalkonium chloride exhibits stronger collecting ability and better foaming performance.

Claims

1. A composite collector for the de-alumination reverse flotation of collophanite, characterized in that, By mass fraction, comprising the following components: 45-55% benzalkonium chloride, 20-30% cocamide propyl hydroxy sultaine, 15-30% isomeric tridecanol polyoxyethylene ether, 3-10% sodium citrate.

2. A composite collector for the reverse flotation of de-alumination of collophanite according to claim 1, characterized in that, The benzalkonium chloride alkyl chain is C12-C14, preferably the benzalkonium chloride with alkyl chain C12 and the benzalkonium chloride with alkyl chain C14 are compounded in a mass ratio of 1: (1-1.5).

3. A composite collector for the reverse flotation of de-alumination of collophanite according to claim 1, characterized in that, The isomeric tridecanol polyoxyethylene ether has a polymerization degree of 7-9.

4. A method for preparing a composite collector for reverse flotation of de-alumination of collophanite, characterized by, Comprising the following steps: S1, under the protection of nitrogen, heating and stirring benzalkonium chloride and cocamide propyl hydroxy sultaine at 80±5℃ to obtain mixture A; S2, cooling mixture A to 45-50℃, adding isomeric tridecanol polyoxyethylene ether, shearing and emulsifying to obtain emulsion B; S3, cooling emulsion B to 35-40℃, adding sodium citrate and stirring to obtain emulsion C; S4, cooling emulsion C to 25±5℃, adding citric acid to adjust pH to 6-6.5 to obtain composite collector.

5. A process for the preparation of a composite collector for the reverse flotation of de-aluminized collophanite according to claim 4, characterized in that, The nitrogen flow in S1 is 0.8-1.2 L / min; The cooling rate in S2 is 2-3℃ / min, the shearing rate is 400-800 rpm, and the shearing time is 5-15 min; The cooling rate in S3 is 2-3℃ / min, the stirring rate is 100-500 rpm, and the stirring time is 2-8 min.

6. The method of claim 4, wherein the method is characterized by, The particle size of the sodium citrate is <200 mesh.

7. The composite collector according to any one of claims 1-3 or obtained by the preparation method of any one of claims 4-6 is used for collophanite reverse flotation for removing aluminum.

8. Use according to claim 7, characterized in that, Comprising the following steps: (1) grinding collophanite to -200 mesh ≥65%, adding water to adjust the pulp concentration to 25-30%, and adjusting pH to 4.5-5.5 with sulfuric acid; (2) adding 0.3-1.0 kg / t of ore of the collector and stirring for 1-5 min; (3) Flotation for 5-8 minutes with 0.3-1.0 m 3 (m 2 per minute to obtain refined phosphate ore.

9. Use according to claim 7, characterized in that, The collophanite is low-grade collophanite or medium-grade collophanite.

10. Use according to claim 7, characterized in that, The reverse flotation temperature for removing aluminum is 10-40℃.