Magnetic separation-flotation combined stepped deep iron removal method for granite tailings

Abstract

The invention discloses a magnetic separation-flotation combined stepped deep iron removal method for granite tailings. According to the method, after granite tailings are subjected to ore grinding treatment, magnetic separation impurity removal, black and white mica ore removal through reverse flotation and fine ferrodolomite ore removal through reverse flotation are conducted in sequence, after the pH of reverse flotation tailings is adjusted, fluoride-free and acid-free separation is conducted, low-iron quartz concentrate and feldspar rough concentrate are obtained, the feldspar rough concentrate is subjected to regrinding and secondary magnetic separation impurity removal, and the low-iron quartz concentrate and the feldspar rough concentrate are obtained. And low-iron feldspar concentrate is obtained. According to the method, no strong acid is involved in the whole process, the technical problem that in the prior art, strong acid is introduced in quartz and feldspar flotation, and consequently waste water and waste liquid pollution is caused is fundamentally solved, and efficient and deep removal of iron impurities in the granite tailings is achieved through the magnetic separation pre-enrichment-three-section flotation separation-step deep iron removal technology. And the overall removal efficiency of the iron impurities is remarkably improved, and comprehensive utilization of granite tailings resources is achieved.

Description

Technical Field

[0001] The present invention relates to a method for removing iron from granite tailings, specifically to a combined magnetic separation - flotation cascade deep iron removal method for granite tailings, belonging 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 the uniform distribution of crystal clusters and few impurities in the crystals. Among them, quartz can be used for high - purity quartz glass, and feldspar can be used for high - end ceramic billets. However, both have extremely high requirements for iron content: too high iron content in the glass industry will significantly reduce the light transmittance, and iron impurities in ceramic applications will cause color differences in the fired body of the billet, unable to meet high - end requirements. Currently, the methods for removing iron from tailings include magnetic separation, flotation, and chemical pickling methods. However, traditional processes have problems such as low efficiency, high environmental pollution, or insufficient product purity. For example, strong acid leaching causes serious pollution, single magnetic separation is insufficient for removing fine - grained iron minerals, and although flotation can separate mica, it is limited by the environmental harm of fluoride flotation agents and the poor separation effect between quartz and feldspar.

[0003] In recent years, combined processes have received attention due to their low cost and small pollution. However, existing technologies mostly rely on acid leaching or simple process series. Therefore, there is an urgent need in the market to develop an efficient and environmentally friendly technology to break through the bottleneck of granite tailings resource utilization. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention aims to provide a combined magnetic separation - flotation cascade deep iron removal method for granite tailings. This method realizes the efficient and deep removal of iron impurities in granite tailings through a three - stage process of "magnetic separation pre - enrichment - three - stage flotation separation - cascade deep iron removal". 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, greatly improve the comprehensive resource utilization rate of granite tailings, and thus realize the transformation from "waste" to "high - purity raw materials".

[0005] To achieve the above technical objectives, the present invention provides a combined magnetic separation - flotation cascade deep iron removal method for granite tailings, including: after grinding the granite tailings, successively passing through single - stage magnetic separation for impurity removal, reverse flotation for removing biotite and reverse flotation for removing fine - grained ankerite. After adjusting the pH of the reverse flotation tailings, fluoride - free and acid - free separation is carried out to obtain low - iron quartz concentrate and feldspar rough concentrate. The feldspar rough concentrate is re - ground and then undergoes two - 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 dosage of flotation reagents, reduce production costs, and improve the recovery rate of products while ensuring no fluorine and no acid throughout the process. On the other hand, it can also efficiently separate various oxidized ores and silicate minerals, significantly reducing the iron content in the products. It should be noted that this method needs to be strictly implemented in accordance with the above requirements. When only magnetic separation is used, it is almost impossible to separate silicate minerals from each other, and it is difficult to obtain high - purity quartz products. When only flotation is used, it will lead to an increase in the dosage of reagents, a longer separation process, and too high an iron content in the products, resulting in poor product quality.

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

[0008] As a preferred solution, the conditions for the first - stage magnetic separation for impurity removal are as follows: a magnetic separator with a magnetic induction intensity of 1.0 - 1.5 T is used to magnetically separate the tailings after rough grinding until a constant weight is achieved.

[0009] As a preferred solution, sodium carbonate needs to be added to adjust the pH of the pulp to 10 - 11 before reverse flotation to remove biotite.

[0010] As a preferred solution, the anionic - cationic composite collector for reverse flotation to remove biotite includes an anionic collector composition and a cationic collector composition, and the mass ratio of the two is 2 - 4:1.

[0011] The anionic - cationic composite collector provided by the present invention needs to be compounded strictly in accordance with the above requirements, so as to target minerals with different surface electricities simultaneously, significantly reducing the dosage of reagents while significantly improving the flotation efficiency and selectivity.

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

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

[0014] As a preferred solution, the foaming agent for reverse flotation to remove biotite is one of diesel oil, kerosene, paraffin oil, eucalyptus oil, pine oil, and cresylic acid.

[0015] As a preferred solution, the mass ratio of the anionic - cationic composite collector to the foaming agent for reverse flotation to remove biotite is 13 - 15:1.

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

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

[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 ether amine.

[0020] The main purpose of the collector at this stage is to remove fine-grained ankerite in the material. Among them, the anionic collector adsorbs the iron active sites in ankerite through carboxyl groups, and the cationic collector adsorbs the carbonate region in dolomite through amino groups to form complementary coverage.

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

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

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

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

[0025] As a preferred solution, the process of the second-stage magnetic separation for impurity removal is as follows: using a magnetic separator with a magnetic induction intensity of 1.0-1.5 T to magnetically separate the ground feldspar rough concentrate until it reaches a constant weight.

[0026] As a preferred solution, the SiO2 content in the quartz concentrate is ≥99.5%, the iron content is ≤90 ppm, 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 as follows:

[0029] 1) The method provided by the present invention removes large - particle iron - containing impurities in granite tailings through one - stage grinding and one - stage magnetic separation. Then, it separates muscovite and biotite with poor dissociation ability through one - stage flotation. Next, it uses flotation reagents including cationic and anionic collectors to remove fine - grained ankerite, and then through a fluorine - free and acid - free separation process, it separates quartz concentrate and feldspar rough concentrate, and performs two - stage grinding and two - stage magnetic separation on the feldspar rough concentrate to obtain feldspar concentrate. This method has no strong acid intervention throughout the 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, through the process of magnetic separation pre - enrichment - three - stage flotation separation - cascade deep iron removal, the efficient and deep removal of iron impurities in granite tailings is realized. Compared with the inefficient capture of fine - grained iron minerals by the 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, greatly improve the comprehensive utilization rate of granite tailings resources, and thus realize the transformation from "waste" to "high - purity raw materials". BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is the process flow diagram of the magnetic separation - flotation combined cascade deep iron removal method provided in Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in conjunction with the specification drawings and preferred embodiments. It should be noted that the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0033] Embodiment 1

[0034] This embodiment provides a magnetic separation - flotation combined cascade deep iron removal method for granite tailings. The specific process is as follows: 1) Place granite tailings (with SiO2, K2O, and Na2O contents of 75.41%, 5.22%, and 1.45% respectively) in a conical ball mill for rough grinding to make the grinding fineness such that the proportion of - 200 mesh is 10%. Place the ground slurry in a flotation cell and add an appropriate amount of water to adjust the pulp concentration. Perform wet magnetic separation on the slurry at a magnetic field intensity of 1.2 T to remove some iron - containing minerals (biotite, ankerite);

[0035] 2) Add sodium carbonate to the magnetic separation tailings to adjust the pulp pH to 10, then add 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 to float mica and coarse-grained biotite minerals with poor dissociation;

[0036] 3) Conduct pulp conditioning on the tailings after flotation, sequentially add a mixture of 350 g / t of sodium hexametaphosphate and 150 g / t of carboxymethyl cellulose as an inhibitor, a total of 50 g / t of dodecylamine and ether amine with a mass ratio of 1:1, and a total of 100 g / t of oleic acid and sodium sulfonate with a mass ratio of 1:1 as collectors to float and separate fine-grained ankerite to obtain a mixed product of quartz and feldspar;

[0037] 4) Add a mixed inhibitor of 600 g / t of sodium silicate, soluble starch, and sodium hexametaphosphate with a ratio of 1:1:1 to the mixed product of quartz and feldspar, adjust the pH to 4 - 5 with sodium carbonate, and separate quartz and feldspar by roughing flotation of feldspar to obtain high-purity quartz concentrate and feldspar rough concentrate;

[0038] 5) Regrind the feldspar rough concentrate until the proportion of materials with a particle size of -0.074 mm is 70 ± 5%, and place the reground slurry in a wet magnetic separator with a magnetic field intensity of 1.2 T for secondary iron removal to obtain feldspar magnetic separation tailings;

[0039] Through steps 1) - 5), high-purity quartz concentrate and feldspar concentrate can be obtained; among them, the SiO2 content in the quartz concentrate is 99.6%, the iron content is 80 ppm, the whiteness is 96, the content of the mixture of K2O and Na2O 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 example is exactly the same as that of Example 1, and the difference lies in that the rough grinding time of the granite tailings in the conical ball mill is increased so that the grinding fineness is 15% with a particle size of -200 mesh.

[0042] Through this example, high-purity quartz concentrate and feldspar concentrate can be obtained; among them, the SiO2 content in the quartz concentrate is 99.5%, the iron content is 85 ppm, the whiteness is 96, the content of the mixture of K2O and Na2O 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, and the difference lies in that the magnetic field intensity of the wet magnetic separator for two-stage magnetic separation is adjusted to 1.4T.

[0045] High-purity quartz concentrate and feldspar concentrate can be obtained through this embodiment; among them, the SiO2 content in the quartz concentrate is 99.7%, the iron content is 60 ppm, the whiteness is 97, and the content of the mixture of K2O and Na2O 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] Embodiment 4

[0047] The process of this embodiment is exactly the same as that of Embodiment 1, and the difference lies in 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; among them, the SiO2 content in the quartz concentrate is 99.6%, the iron content is 85 ppm, the whiteness is 95, and the content of the mixture of K2O and Na2O 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 Embodiment 1, and the difference lies in that the feldspar rough concentrate is directly used as the final product without magnetic separation.

[0051] Only high-purity quartz and feldspar products with a relatively high iron content can be obtained as the final product: Quartz concentrate: SiO2 content 99.4%, iron content 60 ppm, whiteness reaching 97; Feldspar concentrate: 10.8% of K2O and Na2O, 16.6% of Al2O3, 0.35% of iron content.

[0052] Comparative Example 2

[0053] The process of this comparative example is exactly the same as that of Embodiment 1, and the difference lies in that magnetic separation at 1 - 1.5T is not carried out after the first stage of grinding.

[0054] The final products are quartz and feldspar products with a relatively high iron content and poor quality: Quartz concentrate: SiO2 content 98.1%, iron content 1350 ppm; Feldspar concentrate: 8.4% of K2O and Na2O, 14.1% of Al2O3, 1.23% of iron content.

[0055] Comparative Example 3

[0056] The process of this comparative example is exactly the same as that of Embodiment 1, and the difference lies in that no primary flotation is carried out, and muscovite and poorly dissociated coarse-grained biotite are not separated.

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

Claims

1. A combined magnetic separation - flotation cascade deep iron removal method for granite tailings, characterized in that: After the granite tailings are subjected to grinding treatment, they are successively subjected to first-stage magnetic separation for impurity removal, reverse flotation for removing biotite mica ore, and reverse flotation for removing fine-grained ankerite ore. After the pH of the reverse flotation tailings is adjusted, fluorine-free and acid-free separation is carried out to obtain low-iron quartz concentrate and feldspar rough concentrate. The feldspar rough concentrate is reground and subjected to second-stage magnetic separation for impurity removal to obtain low-iron feldspar concentrate.

2. The magnetic separation - flotation combined cascade deep iron removal method for granite tailings according to claim 1, wherein: The conditions for the grinding treatment are as follows: the granite tailings are ground until the proportion of materials with a particle size of -0.074 mm accounts for 10 - 20%; the conditions for the first-stage magnetic separation for impurity removal are as follows: a magnetic separator with a magnetic induction intensity of 1.0 - 1.5 T is used to magnetically separate the tailings after rough grinding until a constant weight is achieved.

3. A method for combined magnetic separation - flotation cascade deep iron removal from granite tailings according to claim 1, characterized in that: Before the reverse flotation for removing biotite mica ore, sodium carbonate needs to be added to adjust the pH of the pulp to 10 - 11; the anionic and cationic composite collector for the reverse flotation for removing biotite mica ore includes an anionic collector composition and a cationic collector composition, and the mass ratio of the two is 2 - 4:

1.

4. A method for combined magnetic separation - flotation cascade deep iron removal from granite tailings according to claim 3, characterized in that: The anionic collector composition includes sodium oleate with a mass proportion of 50% or more and at least two different fatty acid collectors; the cationic collector composition includes dodecylamine acetate with a mass proportion of 50% or more and at least two different amine collectors.

5. A method for combined magnetic separation - flotation cascade deep iron removal of granite tailings according to claim 1, characterized in that: The foaming agent for the reverse flotation for removing biotite mica ore is one of diesel oil, kerosene, paraffin oil, eucalyptus oil, pine oil, and cresylic acid; the mass ratio of the anionic and cationic composite collector to the foaming agent for the reverse flotation for removing biotite mica ore is 13 - 15:

1.

6. A method for combined magnetic separation - flotation cascade deep iron removal of granite tailings according to claim 1, characterized in that: Before the reverse flotation for removing fine-grained ankerite ore, sodium carbonate needs to be added to adjust the pH of the pulp to 10 - 11; the collector for the reverse flotation for removing fine-grained ankerite ore includes an anionic collector and a cationic collector with a mass ratio of 2 - 3:1; the anionic collector is oleic acid and / or sodium sulfonate; the cationic collector is dodecylamine and / or ether amine.

7. A method for jointly and stepwise deeply removing iron by magnetic separation - flotation of granite tailings according to claim 1, characterized in that: The process of adjusting the pH of the reverse flotation tailings is as follows: the pH of the reverse flotation tailings is adjusted to 4 - 5 using sodium carbonate.

8. A method for combined magnetic separation and flotation cascade deep iron removal of granite tailings according to claim 1, characterized in that: The conditions for the regrinding treatment are as follows: the feldspar rough concentrate is ground until the mass proportion of materials with a particle size of -0.074 mm accounts for 70 ± 5%; the process of the second-stage magnetic separation for impurity removal is as follows: a magnetic separator with a magnetic induction intensity of 1.0 - 1.5 T is used to magnetically separate the ground feldspar rough concentrate until a constant weight is achieved.

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

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