A method for deep iron removal of granite tailings by combined magnetic separation and flotation

Abstract

The present invention discloses a method for magnetic separation and flotation combined with step-by-step deep iron removal of granite tailings. According to the method, granite tailings are subjected to grinding treatment, followed by magnetic separation for impurity removal, reverse flotation for removal of black and white mica ore, and reverse flotation for removal of fine-grained ankerite ore. After the pH of the reverse flotation tailings is adjusted, fluorine-free and acid-free separation is performed to obtain low-iron quartz concentrate and feldspar coarse concentrate. The feldspar coarse concentrate is regrinded and subjected to secondary magnetic separation for impurity removal to obtain low-iron feldspar concentrate. The method provided by the present invention does not involve strong acid throughout the entire process, fundamentally solving the technical problem of wastewater and waste liquid pollution caused by the introduction of strong acid in the flotation of quartz and feldspar in the prior art. The method also achieves efficient and deep removal of iron impurities in granite tailings through the magnetic pre-enrichment-three-stage flotation separation-step-by-step deep iron removal process, significantly improving the overall removal efficiency of iron impurities and realizing the comprehensive resource utilization of granite tailings.

Description

Technical Field

[0001] The invention relates to a method for removing iron from granite tailings, in particular to a method for removing iron from granite tailings by combined magnetic separation and flotation stepwise, and belongs to the technical field of mineral processing. Background Art

[0002] Granite tailings are ideal raw materials for obtaining high-quality quartz and feldspar due to their uniform distribution of crystal clusters and low levels of impurities within the crystals. Quartz can be used for high-purity quartz glass, and feldspar can be used for high-end ceramic blanks. However, both have extremely high requirements for iron content: excessive iron content in the glass industry will significantly reduce light transmittance, while iron impurities in ceramic applications will cause color differences in the blanks after firing, which cannot meet high-end needs. Current methods for removing iron from tailings include magnetic separation, flotation, and chemical pickling, but traditional processes have problems such as low efficiency, high environmental pollution, or insufficient product purity. For example, strong acid leaching causes serious pollution, and single magnetic separation is insufficient to remove fine-grained iron minerals. Although flotation can separate mica, it is limited by the environmental hazards of fluoride flotation agents and the poor separation effect of quartz and feldspar.

[0003] In recent years, the combined process has attracted attention due to its low cost and low pollution. However, existing technologies mostly rely on acid leaching or simple process series. Therefore, the market urgently needs to develop an efficient and environmentally friendly technology to break through the bottleneck of granite tailings resource utilization. Summary of the Invention

[0004] To address the problems of the existing technology, the present invention aims to provide a method for deep, step-by-step iron removal from granite tailings using a combined magnetic separation and flotation process. This method achieves efficient, deep removal of iron impurities from granite tailings through a three-stage process: pre-enrichment by magnetic separation, three-stage flotation separation, and deep, step-by-step iron removal. Compared to the inefficient capture of fine-grained iron minerals by a single magnetic separation process in the prior art, the step-by-step separation design provided by the present invention significantly improves the overall removal efficiency of iron impurities and significantly increases the comprehensive resource utilization rate of granite tailings, thereby achieving the transformation from "waste" to "high-purity raw materials."

[0005] In order to achieve the above technical objectives, the present invention provides a method for deep iron removal of granite tailings by combined magnetic separation and flotation, comprising: subjecting the granite tailings to grinding treatment, followed by a first-stage magnetic separation for impurity removal, reverse flotation for removal of black and white mica ore, and reverse flotation for removal of fine-grained ankerite ore; adjusting the pH of the reverse flotation tailings, and then subjecting them to fluorine-free and acid-free separation to obtain low-iron quartz concentrate and feldspar coarse concentrate; and regrinding the feldspar coarse concentrate and subjecting it to a second-stage magnetic separation for impurity removal to obtain low-iron feldspar concentrate.

[0006] The magnetic separation-flotation combined process provided by the present invention can significantly reduce the amount of flotation reagents used, reduce production costs, and improve product recovery while ensuring that the entire process is fluorine-free and acid-free. On the other hand, it can also efficiently separate a variety of oxide ores and silicate minerals, significantly reducing the iron content in the product. It should be noted that this method must be strictly implemented in accordance with the above requirements. When only magnetic separation is used, the silicate minerals are almost impossible to separate, making it difficult to obtain high-purity quartz products. When only flotation is used, the amount of reagents used will increase, the separation process will become longer, and the iron content in the product will be too high, resulting in poor product quality.

[0007] As a preferred solution, the grinding treatment conditions are: the granite tailings are ground to a particle size of -0.074 mm, with the proportion of the material being 10-20%.

[0008] As a preferred solution, the condition for the first stage of magnetic separation and impurity removal is: using a magnetic separator with a magnetic induction intensity of 1.0~1.5T to magnetically separate the coarsely ground tailings to a constant weight.

[0009] As a preferred solution, sodium carbonate is added before the reverse flotation to remove the monochromatic mica ore to adjust the slurry pH to 10-11.

[0010] As a preferred solution, the anionic and cationic composite collector for reverse flotation removal of monochromatic mica ore comprises an anionic collector composition and a cationic collector composition, and the mass ratio of the two is 2 to 4:1.

[0011] The anion-cation composite collector provided by the present invention must be compounded strictly in accordance with the above requirements, so as to simultaneously target minerals with different surface electrical properties, significantly reducing the amount of reagents used while significantly improving flotation efficiency and selectivity.

[0012] As a preferred solution, the anionic collector composition includes 50% by weight or more of sodium oleate and at least two different fatty acid collectors.

[0013] As a preferred solution, the cationic collector composition includes 50% by mass or more of dodecylamine acetate and at least two different amine collectors.

[0014] As a preferred solution, the foaming agent for reverse flotation removal of black and white mica ore is one of diesel, kerosene, paraffin oil, eucalyptus oil, pine oil and cresol acid.

[0015] As a preferred solution, the mass ratio of the anion-cation composite collector to the frother for removing the monochromatic mica ore by reverse flotation is 13-15:1.

[0016] As a preferred solution, sodium carbonate is added to adjust the pH of the slurry to 10-11 before the reverse flotation to remove the fine-grained ankerite ore.

[0017] As a preferred solution, the collector for removing fine-grained ankerite ore by reverse flotation comprises an anionic collector and a cationic collector in a mass ratio of 2 to 3:1.

[0018] As a preferred solution, the anionic collector is oleic acid and / or sodium sulfonate.

[0019] As a preferred solution, the cationic collector is dodecylamine and / or etheramine.

[0020] The main purpose of the collector in this stage is to remove the fine-grained ankerite in the material. The anionic collector adsorbs the iron active sites in the ankerite through the carboxyl group, and the cationic collector adsorbs the carbonate areas in the dolomite through the amine group, forming a complementary coverage.

[0021] As a preferred solution, the process of adjusting the pH of the reverse flotation tailings is: adjusting the pH of the reverse flotation tailings to 4-5 using sodium carbonate.

[0022] As a preferred solution, the second-stage inhibitor is at least two of sodium silicate, soluble starch, sodium hexametaphosphate, sodium lignin and sodium silicate.

[0023] As a preferred solution, the second-stage inhibitor consists of 50% by mass of sodium hexametaphosphate and 50% by mass of carboxymethyl cellulose.

[0024] As a preferred solution, the conditions for the regrinding treatment are: grinding the coarse feldspar concentrate to a particle size of -0.074 mm, where the mass proportion of the material is 70±5%.

[0025] As a preferred solution, the two-stage magnetic separation and impurity removal process is: using a magnetic separator with a magnetic induction intensity of 1.0~1.5T to magnetically separate the ground feldspar coarse concentrate to a constant weight.

[0026] As a preferred solution, the SiO2 content in the quartz concentrate is ≥99.5%, the iron content is ≤90ppm, and the whiteness is ≥95.

[0027] As a preferred solution, the iron content in the feldspar concentrate is ≤0.14% and the whiteness is ≥56.

[0028] Compared with the prior art, the beneficial technical effects of the technical solution of the present invention are:

[0029] 1) The method provided by the present invention removes large-particle iron-containing impurities from granite tailings through a first-stage grinding and a first-stage magnetic separation. Muscovite and biotite with poor dissociation ability are then separated through a first-stage flotation. Flotation agents including anionic and cationic collectors are then used to remove fine ankerite. Quartz concentrate and feldspar coarse concentrate are then separated through a fluorine-free and acid-free separation process. The feldspar coarse concentrate is then subjected to a second-stage grinding and a second-stage magnetic separation to obtain a feldspar concentrate. This method does not involve the intervention of strong acid throughout the entire process, fundamentally solving the technical problem of wastewater and waste liquid pollution caused by acid leaching in the prior art.

[0030] 2) In the technical solution provided by the present invention, the efficient and deep removal of iron impurities in granite tailings is achieved through a magnetic separation pre-enrichment-three-stage flotation separation-cascade deep iron removal process. Compared with the inefficient capture of fine-grained iron minerals by a single magnetic separation process in the prior art, the cascade separation design provided by the present invention can significantly improve the overall removal efficiency of iron impurities and greatly improve the comprehensive resource utilization rate of granite tailings, thereby realizing the transformation from "waste" to "high-purity raw materials." BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a process flow chart of the magnetic separation-flotation combined step-by-step deep iron removal method provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] To facilitate understanding of the present invention, the present invention will be described in more detail below in conjunction with the accompanying drawings and preferred embodiments. It should be noted that the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for deep iron removal from granite tailings by combining magnetic separation and flotation. The specific process is as follows: 1) granite tailings (containing 75.41%, 5.22%, and 1.45% SiO2, K2O, and Na2O, respectively) are coarsely ground in a conical ball mill to a fineness of -200 mesh (10%). The ground slurry is then placed in a flotation tank, and water is added to adjust the slurry concentration. The slurry is then wet-magnetically separated at a magnetic field strength of 1.2 T to remove some iron-containing minerals (biotite and ankerite).

[0035] 2) Sodium carbonate was added to the magnetic separation tailings to adjust the pulp pH to 10. Then, 300 g / t of TB1 (sodium oleate: fatty acid = 1:1), 100 g / t of TB2 (dodecylamine acetate: amine = 1:1), 80 g / t of diesel, and 30 g / t of pine oil were added to float muscovite and poorly dissociated coarse biotite minerals.

[0036] 3) The tailings after flotation are subjected to flotation slurry adjustment, and a mixture of 350g / t sodium hexametaphosphate and 150g / t carboxymethyl cellulose is added in sequence as an inhibitor, 50g / t of dodecylamine and etheramine in a mass ratio of 1:1, and 100g / t of oleic acid and sodium sulfonate in a mass ratio of 1:1 are added as collectors to separate fine-grained ankerite by flotation to obtain a mixed product of quartz and feldspar;

[0037] 4) Adding 600g / t of a mixed inhibitor of sodium silicate, soluble starch, and sodium hexametaphosphate in a ratio of 1:1:1 to the mixed product of quartz and feldspar, adjusting the pH to 4-5 with sodium carbonate, and separating the quartz and feldspar by coarse-grained flotation of feldspar to obtain high-purity quartz concentrate and feldspar coarse concentrate;

[0038] 5) The feldspar coarse concentrate is re-ground to a material ratio of -0.074 mm of 70 ± 5%. The re-ground slurry is placed in a wet magnetic separator with a magnetic field strength of 1.2 T for secondary iron removal to obtain feldspar magnetic separation tailings;

[0039] After steps 1) to 5), high-purity quartz concentrate and feldspar concentrate can be obtained; wherein, the SiO2 content in the quartz concentrate is 99.6%, the iron content is 80 ppm, and the whiteness is 96; the content of the K2O and Na2O mixture in the feldspar concentrate is 12.5%, the Al2O3 content is 16.9%, the iron content is 0.11%, and the whiteness is 60.

[0040] Example 2

[0041] The process of this embodiment is exactly the same as that of embodiment 1, except that the granite tailings are placed in the conical ball mill for a longer coarse grinding time, so that the grinding fineness is -200 mesh, accounting for 15%.

[0042] High-purity quartz concentrate and feldspar concentrate can be obtained through this embodiment; wherein, the SiO2 content in the quartz concentrate is 99.5%, the iron content is 85ppm, and the whiteness is 96; the content of the K2O and Na2O mixture in the feldspar concentrate is 12.3%, the Al2O3 content is 16.8%, the iron content is 0.13%, and the whiteness is 57.

[0043] Example 3

[0044] The process of this embodiment is exactly the same as that of embodiment 1, except that the magnetic field strength of the wet magnetic separator for the two-stage magnetic separation is adjusted to 1.4T.

[0045] High-purity quartz concentrate and feldspar concentrate can be obtained through this embodiment; wherein, the SiO2 content in the quartz concentrate is 99.7%, the iron content is 60 ppm, and the whiteness is 97; the content of the K2O and Na2O mixture in the feldspar concentrate is 12.8%, the Al2O3 content is 17.1%, the iron content is 0.09%, and the whiteness is 64.

[0046] Example 4

[0047] The process of this embodiment is exactly the same as that of Example 1, except that sodium carbonate is added to the magnetic separation tailings to adjust the pH value to 10.7.

[0048] High-purity quartz concentrate and feldspar concentrate can be obtained through this embodiment; wherein, the SiO2 content in the quartz concentrate is 99.6%, the iron content is 85ppm, and the whiteness is 95; the content of the K2O and Na2O mixture in the feldspar concentrate is 12.6%, the Al2O3 content is 16.8%, the iron content is 0.12%, and the whiteness is 59.

[0049] Comparative Example 1

[0050] The process of this comparative example is exactly the same as that of Example 1, except that the feldspar coarse concentrate is directly used as the final product without undergoing magnetic separation.

[0051] The final products can only produce high-purity quartz and feldspar products with high iron content: quartz concentrate: SiO2 content 99.4%, iron content 60ppm, reaching 97% whiteness; feldspar concentrate: 10.8% K2O and Na2O, 16.6% Al2O3, 0.35% iron content.

[0052] Comparative Example 2

[0053] The process of this comparative example is exactly the same as that of Example 1, except that no 1-1.5 T magnetic separation is performed after the first stage of grinding.

[0054] The final products are quartz and feldspar products with higher iron content and lower quality: quartz concentrate: SiO2 content 98.1%, iron content 1350ppm; feldspar concentrate: 8.4% K2O and Na2O, 14.1% Al2O3, 1.23% iron content.

[0055] Comparative Example 3

[0056] The process of this comparative example is exactly the same as that of Example 1, except that no flotation is performed, and the muscovite and poorly dissociated coarse biotite are not separated.

[0057] The final products are quartz of lower quality and feldspar products with higher iron content and lower quality: quartz concentrate: SiO2 content 88.61%, iron content 2533ppm; feldspar concentrate: 6.5% K2O and Na2O, 13.1% Al2O3, iron content 1.80%.

Claims

1. A method for removing iron from granite tailings by combining magnetic separation and flotation, characterized by: After the granite tailings are ground, they are sequentially subjected to a first-stage magnetic separation to remove impurities, reverse flotation to remove black and white mica ore, and reverse flotation to remove fine-grained ankerite ore. After the reverse flotation tailings have their pH adjusted, they are subjected to fluorine-free and acid-free separation to obtain low-iron quartz concentrate and feldspar coarse concentrate. The feldspar coarse concentrate is regrinded and subjected to a second-stage magnetic separation to remove impurities to obtain low-iron feldspar concentrate. The anionic and cationic composite collector for reverse flotation removal of black and white mica ore comprises an anionic collector composition and a cationic collector composition, the mass ratio of the two being 2 to 4:1; The anionic collector composition includes sodium oleate accounting for 50% by weight or more and at least two different fatty acid collectors; the cationic collector composition includes dodecylamine acetate accounting for 50% by weight or more and at least two different amine collectors; The collector for removing fine-grained ankerite ore by reverse flotation comprises an anionic collector and a cationic collector in a mass ratio of 2 to 3:1; the anionic collector is oleic acid and / or sodium sulfonate; and the cationic collector is dodecylamine and / or etheramine.

2. The method for removing iron from granite tailings by combined magnetic separation and flotation stepwise deep separation according to claim 1, characterized in that: The conditions for the grinding treatment are: the granite tailings are ground to a particle size of -0.074 mm, with the proportion of the material being 10-20%; the conditions for the first-stage magnetic separation and impurity removal are: a magnetic separator with a magnetic induction intensity of 1.0-1.5T is used to magnetically separate the coarsely ground tailings to a constant weight.

3. The method for removing iron from granite tailings by combined magnetic separation and flotation stepwise deep separation according to claim 1, characterized in that: Before the reverse flotation to remove the black and white mica ore, sodium carbonate needs to be added to adjust the pH of the slurry to 10-11.

4. The method for removing iron from granite tailings by combined magnetic separation and flotation stepwise deep separation according to claim 1, characterized in that: The foaming agent for reverse flotation removal of black and white mica ore is one of diesel, kerosene, paraffin oil, eucalyptus oil, pine oil and cresol acid; the mass ratio of the anion-cation composite collector to the foaming agent for reverse flotation removal of black and white mica ore is 13-15:

1.

5. The method for removing iron from granite tailings by combined magnetic separation and flotation stepwise deep separation according to claim 1, characterized in that: Before the reverse flotation to remove the fine-grained ankerite ore, sodium carbonate needs to be added to adjust the pH of the slurry to 10-11.

6. The method for removing iron from granite tailings by combined magnetic separation and flotation in a stepwise manner according to claim 1, wherein: The process of adjusting the pH of the reverse flotation tailings is as follows: adjusting the pH of the reverse flotation tailings to 4-5 using sodium carbonate.

7. The method for removing iron from granite tailings by combined magnetic separation and flotation in a stepwise manner according to claim 1, wherein: The conditions for the regrinding treatment are: grinding the feldspar coarse concentrate to a particle size of -0.074 mm, with a material mass ratio of 70±5%; the process of the second-stage magnetic separation and impurity removal is: using a magnetic separator with a magnetic induction intensity of 1.0~1.5T to magnetically separate the ground feldspar coarse concentrate to a constant weight.

8. A method for removing iron from granite tailings by combined magnetic separation and flotation stepwise deep separation according to any one of claims 1 to 7, characterized in that: SiO2 in the quartz concentrate The content is ≥99.5%, the iron content is ≤90ppm, and the whiteness is ≥95; the iron content in the feldspar concentrate is ≤0.14%, and the whiteness is ≥56.

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