A combined grinding aid for enhancing the flotation separation of magnesite and dolomite and its application

Abstract

This invention relates to the field of mineral processing technology and relates to a combined grinding aid for enhancing the flotation separation of magnesite and dolomite. By optimizing grinding parameters and introducing the combined grinding aid, it achieves the effects of reducing over-grinding, inhibiting the transformation of mineral surface properties, and enhancing the flotation separation of magnesite and dolomite. The combined grinding aid and its application provided by this invention have the advantages of low dosage, high efficiency, and low cost.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology and relates to the grinding and flotation separation of magnesite and dolomite. Background Technology

[0002] Liaoning Province is rich in magnesium resources, especially magnesite and talc, which are its advantageous non-metallic minerals. Despite this abundance, the utilization of magnesium resources suffers from low efficiency and waste. Furthermore, the practice of mining high-grade ore and discarding lower-grade ore is prevalent, resulting in the dumping and stockpiling of large quantities of low-grade ore. This not only causes serious resource waste but also severe environmental pollution. Low-grade magnesite contains a large amount of dolomite. During flotation, dolomite and magnesite have very similar chemical compositions, surface properties, and crystal structures. Both are polar minerals, and their fractured surfaces exhibit ionic bonds, strong hydrophilicity, and are difficult to float. In the crystal lattice, calcium, magnesium, and iron can interchange to form isomorphous structures, making magnesite and dolomite difficult to separate. With the decreasing availability of high-quality magnesite resources, in order to meet the needs of magnesite industrial production and domestic and international markets, the existing magnesite beneficiation process for obtaining high-quality magnesite concentrate has gradually revealed problems such as high cost, low utilization rate of magnesite resources, serious resource waste, increased tailings volume, occupation of large amounts of soil, and serious environmental pollution.

[0003] Grinding is a process preceding flotation. During this process, various factors, including physicochemical, electrochemical, and mechanical factors, cause significant selective dissolution of the mineral surface, affecting its surface morphology and the chemical properties of the pulp solution. As a necessary step before flotation, grinding is not only energy-intensive, accounting for a large proportion of production costs, but also has a significant impact on subsequent magnesite flotation indicators. The addition of grinding aids can effectively reduce grinding energy consumption and improve mineral flotation behavior, significantly influencing ore separation. Grinding is a high-energy-consuming operation, accounting for over 60% of the total energy consumption of the entire concentrator. Therefore, based on the needs of magnesite production, adding appropriate grinding aids during the grinding stage can reduce grinding energy consumption, prevent over-grinding, achieve higher monomer cleavage, increase the surface property differences between magnesite and dolomite, and promote the efficient development and utilization of magnesite resources. Studies have found that due to the high solubility of magnesite and dolomite, surface transformation or heterogeneous aggregation occurs between them in the flotation system, leading to a convergence of mineral surface properties. This is the main reason for the difficulty in separating magnesite through direct flotation. Therefore, improving the flotation separation efficiency of magnesite and reducing tailings production are of great significance for promoting the sustainable development of magnesite resources. Summary of the Invention

[0004] Addressing the technical challenges of poor grinding efficiency and high energy consumption of magnesite and dolomite in the prior art, and the difficulty in flotation separation due to surface transformation or heterogeneous agglomeration of the two minerals in the flotation system, this invention optimizes key grinding parameters such as grinding media size and ratio, media filling rate, feed-to-ball ratio, grinding concentration, and grinding time. Simultaneously, it introduces highly efficient combined grinding aids during the grinding process to selectively improve grinding performance, mitigate the impact of over-grinding on fine-particle products on flotation, and effectively suppress the surface property transformation of the two minerals, thereby enhancing subsequent flotation separation.

[0005] This invention provides a combined grinding aid for optimizing the magnesite grinding and flotation system, the combined grinding aid being composed of inorganic phosphates, organic amines, polar alkanolamines, and water.

[0006] Furthermore, in the above technical solution, the inorganic phosphate is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate; the organic amine agent is selected from one or more of propylamine, butylamine, and pentylamine; the polar alkanolamine organic agent is selected from one or more of diethanolamine, triethanolamine, and triisopropanolamine; the mass fraction of each monomer in the combined grinding aid is: 20%–40% inorganic phosphate, 10%–20% organic amine agent, 20%–40% alkanolamine agent, and the remainder is water.

[0007] This invention also provides a method for efficiently separating magnesite and dolomite, the process of which is as follows: Figure 1 As shown, magnesite and dolomite are wet-ground using ceramic ball media. A combination of grinding aids is added during the grinding process, and after setting the grinding time, the slurry is obtained. The slurry is then transferred to a flotation cell, the pH value of the slurry is adjusted, and an inhibitor is added. Finally, a collector is added to obtain magnesite concentrate.

[0008] Furthermore, the above technical solution specifically includes the following steps:

[0009] (1) Determine grinding parameters;

[0010] (2) Determine the quality of the material fed into the mill and the amount of water used for wet grinding;

[0011] (3) Under the grinding working parameters determined in steps (1) and (2), after adding the grinding material into the mill, the combined grinding aid is directly mixed with the grinding water and then directly added into the mill. The mill is then turned on to obtain the slurry.

[0012] (4) Transfer the slurry obtained in step (3) to a flotation machine, adjust the pH value of the slurry to 9-12, add inhibitors and collectors for flotation, and obtain concentrate and tailings.

[0013] Furthermore, in the above technical solution, the grinding operating parameters in step (1) are:

[0014] 1) The size and ratio of the grinding balls are: Ф30mm:Ф15mm:Ф8mm = (30~50):(15~30):(20~40) (mass ratio);

[0015] 2) Grinding ball filling rate T: 30-40% (volume ratio);

[0016] 3) Mill speed R: 110~115 r / min;

[0017] 4) Pulp concentration C m 65-80%;

[0018] 5) Material to grinding ball ratio Ф m : 0.75~0.85 (volume ratio);

[0019] 6) Grinding time: 4-9 min.

[0020] Furthermore, in the above technical solution, the grinding ball is a ceramic ball;

[0021] Furthermore, in the above technical solution, the method for determining the quality of the material entering the mill in step (2) is as follows: according to formula W m =0.38VTФ m δ w Determine that V is the effective volume of the mill; δ w Where Φ is the bulk density of the material, T is the filling rate, and Ф is the bulk density of the material. m For the ratio of material to balls, W m For the quality of the materials;

[0022] Furthermore, in the above technical solution, the method for determining the grinding water volume in step (2) is as follows: according to formula C m =W m / (W m +W w )×100% to determine, where C m For grinding concentration, W w For grinding water consumption, W m The quality of the material.

[0023] Furthermore, in the above technical solution, the fineness of the slurry in step (3) is -74μm, accounting for 75% to 90%.

[0024] Furthermore, in the above technical solution, in step (3), the dosage of the combined grinding aid is 100g / t to 500g / t.

[0025] Furthermore, in the above technical solution, in step (4), the inhibitor is a phosphate compound, and the amount added is 3 mg / L to 10 mg / L; the collector is a fatty acid compound, and the amount added is 100 mg / L to 300 mg / L.

[0026] The beneficial effects of this invention are:

[0027] Based on optimized grinding parameters, this invention utilizes a combination of highly efficient grinding aids with appropriate ratios and dosages to improve the grinding effect of magnesite and dolomite. While ensuring the degree of monomer liberation, it increases the content of qualified particle sizes in the grinding product, effectively reducing the generation of fine particles and providing a product with the optimal particle size composition for flotation operations. At the same time, the selective adsorption of the grinding aids on the surfaces of the two minerals amplifies the differences in surface properties between the two minerals, thus enhancing subsequent flotation separation.

[0028] Compared with the prior art, the advantages of the present invention are as follows:

[0029] (1) Conventional flotation separation processes for magnesite and dolomite fail to consider the influence of the grinding process. Grinding, as an important step before flotation, is affected by various factors such as physicochemical, electrochemical, and mechanical processes. A large amount of selective dissolution occurs on the surface of magnesite and dolomite, thus affecting the surface morphology of the minerals and the solution chemistry of the pulp. This invention introduces a highly efficient combined grinding aid into the mineral grinding process. While improving the grinding effect, it can increase the differences in surface properties of the minerals, thereby improving grinding efficiency and enhancing flotation separation.

[0030] (2) The combined grinding aid of the present invention has a selective grinding effect, which can significantly improve the grinding effect of magnesite, while the effect on dolomite is relatively weak.

[0031] (3) The combined grinding aid of this invention requires a small dosage and is easy to add. After mixing the grinding aid with grinding water, it can be directly added to the mill, making it highly operable. At the same time, the dosage of the combined grinding aid is small. Conventional organic macromolecular grinding aids are added at a dosage of 1% to 5% of the mass of the material entering the mill, which requires a large dosage. However, the dosage of the combined grinding aid in this invention is only 0.03% to 0.07% of the mass of the material entering the mill. The dosage is low, the effect is significant, and the cost of reagents can be saved. Attached Figure Description

[0032] Figure 1 Flowchart of the separation process for magnesite and dolomite Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the embodiments. The embodiments listed are for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention. Unless otherwise specified, the raw materials and reagents used in the embodiments can be obtained commercially.

[0034] Example 1

[0035] The magnesite selected in this embodiment has a purity of 97% and an MgO content of 46.38%; [The text abruptly ends here, likely due to an incomplete sentence or missing information.] Figure 1 The method shown for flotation separation includes the following steps:

[0036] (1) Add ceramic ball media with a size and ratio of Ф30mm:Ф15mm:Ф8mm = 30:25:20 (mass ratio) to the mill;

[0037] (2) Add 80g of magnesite to the mill. The purity of the magnesite is 97.0%, and the MgO content is 46.38%.

[0038] (3) Magnesite, the combined grinding aid, and water were mixed and directly added to the mill. The mill was then started to obtain a slurry. At this point, the grinding concentration was 65%; the combined grinding aid had the following mass ratio: sodium tripolyphosphate 20%, propylamine 10%, diethanolamine 40%, and the remainder was water, with an addition amount of 100 g / t; the grinding time was 4 min; and the rotation speed was 112 r / min.

[0039] (4) Transfer the slurry obtained in step (3) to the flotation cell, stir, adjust the pH of the slurry to 9, add 3 mg / L of sodium hexametaphosphate inhibitor and 100 mg / L of sodium oleate collector, stir for 2 min after adding the reagents; flotation yields concentrate and tailings;

[0040] (5) Dry and weigh the flotation product concentrate and tailings respectively, calculate the yield and test the product grade.

[0041] The particle size distribution of magnesite after grinding in Example 1 was as follows: -0.074mm +0.038mm: 49.2%; -0.038mm +0.023mm: 4.8%; -0.023mm: 24.9%; and the flotation recovery rate of magnesite was 80.4%.

[0042] Example 2

[0043] The flotation separation was performed using the same method as in Example 1, with the specific steps being the same as in Example 1, except that:

[0044] (1) Different ores were selected. The ore selected in Example 2 was dolomite, with a purity of 95.7%, a CaO content of 30.68%, and a MgO content of 20.95%.

[0045] (2) The particle size distribution of the products after grinding is different. The particle size distribution of the products after grinding in Example 2 is as follows: -0.074mm +0.038mm: 54.8%; -0.038mm +0.023mm: 4.8%; -0.023mm: 25.1%.

[0046] (3) The flotation effect was different, and the recovery rate of dolomite was 9.2%.

[0047] Example 3

[0048] The flotation separation was performed using the same method as in Example 1, with the specific steps being the same as in Example 1, except that:

[0049] (1) Different ores were selected. The ore selected in Example 3 was an artificial mixed ore made of magnesite and dolomite in a mass ratio of 1:1.

[0050] (2) The particle size distribution of the products after grinding is different. The particle size distribution after grinding in Example 3 is: -0.074mm +0.038mm: 52.6%; -0.038mm +0.023mm: 3.1%; -0.023mm: 27.3%.

[0051] (3) The flotation results were different. The yield of the artificially mixed ore concentrate was 78.8%, the MgO grade in the concentrate was 43.7%, and the CaO grade was 5.6%.

[0052] Example 4

[0053] The flotation separation was performed using the same method as in Example 1, with the specific steps being the same as in Example 1, except that:

[0054] (1) The materials used for grinding and flotation are different. In Example 4, the material fed into the mill was actual magnesite ore, with an MgO grade of 45.35% and a CaO grade of 1.5%.

[0055] (2) The particle size distribution of the products after grinding is different, with -0.074mm +0.038mm: 48.4%; -0.038mm +0.023mm: 2.9%; and -0.023mm: 29.4%.

[0056] (3) The flotation effects were different, with a concentrate yield of 70.8%, a MgO grade of 46.3%, and a CaO grade of 0.82%.

[0057] Comparative Example 1

[0058] The flotation separation was performed using the same method as in Example 1, with the specific steps being the same as in Example 1, except that:

[0059] (1) Different grinding conditions. No grinding aid was used in the grinding process of Comparative Example 1.

[0060] (2) The particle size distribution of the products after grinding differed, with -0.074mm +0.038mm accounting for 44.2%; -0.038mm +0.023mm for 4.1%; and -0.023mm for 26.9%.

[0061] (3) The flotation effect is different; the flotation recovery rate of magnesite is 74.1%.

[0062] Compared with Example 1, the test results of Comparative Example 1 show that the use of combined grinding aids in grinding can increase the content of qualified particle size in magnesite grinding products, reduce the generation of fine particle size, and improve the flotation recovery rate of magnesite.

[0063] Comparative Example 2

[0064] The flotation separation was performed using the same method as in Example 1, with the specific steps being the same as in Example 1, except that:

[0065] (1) Different ores were selected. The feed material for Comparative Example 2 was dolomite, with an MgO content of 20.7% and a CaO content of 30.1%.

[0066] (2) The grinding conditions are different. In Comparative Example 2, no grinding aid is used in the grinding process.

[0067] (3) The particle size distribution of the products after grinding is different, with -0.074mm +0.038mm: 49.1%; -0.038mm +0.023mm: 3.4%; and -0.023mm: 29.8%.

[0068] (4) The flotation effect was different, and the recovery rate of dolomite was 13.7%.

[0069] Compared with Example 2, the experimental results of Comparative Example 2 show that the use of combined grinding aids in grinding can increase the content of qualified particle size in dolomite grinding products, reduce the generation of fine particle size, and improve the flotation recovery rate of dolomite. However, compared with Example 1, the combined grinding aids have a weaker effect on dolomite and a stronger effect on magnesite.

[0070] Comparative Example 3

[0071] The flotation separation was performed using the same method as in Example 1, with the specific steps being the same as in Example 1, except that:

[0072] (1) Different ores were selected. Comparative Example 3 was an artificial mixed ore prepared by mixing magnesite and dolomite in a mass ratio of 1:1.

[0073] (2) Different grinding conditions. Comparative Example 3 did not use grinding aids during the grinding process.

[0074] (3) The particle size distribution of the products after grinding is different, with -0.074mm +0.038mm: 47.7%; -0.038mm +0.023mm: 2.5%; and -0.023mm: 31.1%.

[0075] (4) The flotation effects are different. The yield of artificial mixed mineral concentrate is 75.9%, the MgO grade in the concentrate is 42.3%, and the CaO grade is 6.5%.

[0076] Compared with Example 3, the test results of Comparative Example 3 show that the use of combined grinding aids in grinding can increase the content of qualified particle size in artificial mixed ore, reduce the generation of fine particle size, and improve the yield of concentrate.

[0077] Comparative Example 4

[0078] The method is the same as in Example 1, and the specific steps are the same as in Example 1, except that:

[0079] (1) Different ores were selected. Comparative Example 4 used actual magnesite ore, with an MgO grade of 45.35% and a CaO grade of 1.5%.

[0080] (2) Different grinding conditions. Comparative Example 4 did not use grinding aids during the grinding process.

[0081] (3) The particle size distribution of the products after grinding is different. Among them, -0.074mm +0.038mm: 43.5%; -0.038mm +0.023mm: 1.5%; -0.023mm: 31.6%.

[0082] (4) The flotation results were different, with a concentrate yield of 68.2%, a MgO grade of 44.4%, and a CaO grade of 0.95%.

[0083] Compared with Example 4, the test results of Comparative Example 4 show that the use of combined grinding aids in grinding can increase the content of qualified particle size in the magnesite ore grinding product, reduce the generation of fine particle size, and at the same time increase the concentrate yield and enhance the flotation separation of magnesite and dolomite.

[0084] Comparative Example 5

[0085] The flotation separation was performed using the same method as in Example 1, with the specific steps being the same as in Example 1, except that:

[0086] (1) Different ores were selected. Comparative Example 5 used actual magnesite ore, with an MgO grade of 45.35% and a CaO grade of 1.5%.

[0087] (2) The components of the combined grinding aids are different. The combined grinding aids used in Comparative Example 5 during the grinding process are: 30% sodium hexametaphosphate, 15% butylamine, 30% triethanolamine, and the remainder is water.

[0088] (3) The particle size distribution of the products after grinding is different. Among them, -0.074mm +0.038mm: 44.1%; -0.038mm +0.023mm: 2.7%; -0.023mm: 29.5%.

[0089] (4) The flotation results were different, with a concentrate yield of 69.3%, a MgO grade of 45.1%, and a CaO grade of 0.84%.

[0090] Compared with Example 4, the experimental results of Comparative Example 5 show that using a combination of grinding aids with different components in grinding can also enhance the flotation separation of magnesite and dolomite.

[0091] Comparative Example 6

[0092] The flotation separation was performed using the same method as in Example 1, with the specific steps being the same as in Example 1, except that:

[0093] (1) Different ores were selected. Comparative Example 6 used actual magnesite ore, with an MgO grade of 45.35% and a CaO grade of 1.5%.

[0094] (2) The components of the combined grinding aids are different. The combined grinding aids used in Comparative Example 6 during the grinding process were: 25% sodium pyrophosphate, 18% pentamidine, 30% triisopropanolamine, and the remainder was water.

[0095] (3) The particle size distribution of the products after grinding is different. Among them, -0.074mm +0.038mm: 45.7%; -0.038mm +0.023mm: 3.5%; -0.023mm: 27.5%.

[0096] (4) The flotation results were different, with a concentrate yield of 70.8%, a MgO grade of 45.7%, and a CaO grade of 0.78%.

[0097] Compared with Example 4, the experimental results of Comparative Example 6 show that changing the composition of the combined grinding aid during grinding can also enhance the flotation separation of magnesite and dolomite.

Claims

1. A method for the flotation separation of magnesite and dolomite, characterized in that, The method comprises the following steps: (1) setting grinding parameters; (2) determining the quality of the material entering the mill and the quality of the water for wet grinding; (3) under the grinding parameters determined in step (1), after adding the material entering the mill into the mill, the combined grinding aid is directly mixed with the water for grinding and then added into the mill, and the mill is started to obtain the slurry; The combined grinding aid is composed of inorganic phosphate, organic amine and polar alcohol amine, and water, and the mass fraction of each component is as follows: inorganic phosphate 20-40%, organic amine 10-20%, polar alcohol amine 20-40%, and the rest is water; The inorganic phosphate is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate and sodium pyrophosphate, the organic amine is selected from one or more of propylamine, butylamine and amylamine, and the polar alcohol amine is selected from one or more of diethanolamine, triethanolamine and triisopropanolamine; The amount of the combined grinding aid is 100-500 g / t, and the fineness of the grinding product is 75-90% of -74 μm; (4) transferring the slurry obtained in step (3) to a flotation machine, adjusting the pH value of the slurry, adding a phosphate inhibitor and a fatty acid collector for flotation to obtain a concentrate and a tailing; The amount of the inhibitor is 3-10 mg / L, and the amount of the collector is 100-300 mg / L.

2. The method for the flotation separation of magnesite and dolomite according to claim 1, characterized in that, The grinding parameters in step (1) are as follows: 1) the size of the grinding ball Φ: 8-30 mm; 2) the filling rate of the grinding ball T: 30-40% by volume; 3) the speed of the mill R: 110-115 r / min; 4) the concentration of the slurry Cm: 65-80%; 5) the ratio of the material to the grinding ball Φm: 0.75-0.85 by volume; 6) the grinding time: 4-9 min.

3. The method of magnesite and dolomite flotation separation according to claim 1, characterized by, The method for determining the mass of the material in step (2) is determined according to the formula Wm=0.38VTФ m δ w , wherein V is the effective volume of the mill, δ w is the bulk density of the material, T is the filling rate of the grinding ball, Ф m is the ratio of the material to the ball, and W m is the mass of the material. The method for determining the mass of the water used in wet grinding is determined according to the formula C m =W m / (W m +W w )×100%, wherein C m is the grinding concentration, W w is the amount of water used for grinding, and W m is the mass of the material.

4. The method of magnesite and dolomite flotation separation according to claim 1, characterized by, In step (4), the pH value of the slurry is 9-12.

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