Microwave magnetizing roasting-gradient magnetic separation iron removal method and purification process for quartz ore

Abstract

The invention relates to a microwave magnetizing roasting-gradient magnetic separation iron removal method and purification process for quartz ore. Firstly, impurity minerals / inclusions in ores are magnetically modified through microwave magnetizing roasting, weak magnetic minerals in quartz minerals are converted into strong magnetic minerals through a gaseous reducing agent, introduction of solid impurities is avoided, meanwhile, the Fe-containing gas-liquid inclusions are subjected to heating decomposition and magnetic conversion at the specific temperature, and the Fe-containing gas-liquid inclusions are subjected to magnetic modification; and removing magnetic minerals through a gradient magnetic separation process of permanent magnet-high-strength superconducting magnetic separation to obtain the low-iron quartz sand. Due to the characteristic of selective microwave heating, gas / solid inclusions are more easily broken and exposed outside, the efficiency of impurity removal and purification in the subsequent process is effectively improved, and high-purity quartz sand with Fe less than or equal to 0.05 ppm and SiO2 more than or equal to 99.998% can be obtained by matching with purification processes such as acid leaching, flotation and chloridizing roasting. According to the method, ferromagnetic and weakly magnetic impurities, inclusions and the like in the quartz sand can be removed in a targeted mode, the iron removal effect is extremely good, the process is simple and efficient, and the method is more environmentally friendly.

Description

Technical Field

[0001] The invention relates to the field of natural ore processing and treatment, and is a microwave magnetization roasting-gradient magnetic separation iron removal method and a purification process for quartz ore. Background Art

[0002] High-purity quartz sand is a high-end new material made from high-grade natural minerals through a series of processes. It has the characteristics of high hardness, high compressive resistance, high heat resistance, high insulation, low linear expansion coefficient and excellent electrical insulation. It is widely used in many high-tech fields, such as electric light sources, optical fiber communications, solar cells, semiconductor integrated circuits, precision optical instruments, aerospace, etc.; the SiO2 content of high-purity quartz sand for photovoltaics is required to be ≥99.998%, and the SiO2 content of high-purity quartz sand for semiconductors is required to be ≥99.999%, so there are extremely high requirements for the processing technology of natural ores.

[0003] The preparation process of high-purity quartz sand is complicated, and the quality control of each process is difficult, resulting in high purification and processing costs and low production efficiency. In addition, the scarcity of high-grade ore reserves and other factors make it difficult for domestic high-quality high-purity quartz sand to meet the needs of the rapid development of the industry. At present, the domestic deep processing technology for purifying 4N (SiO2 ≥ 99.99%) and above products mainly adopts the combined process of sorting - coarse crushing - calcination - water quenching - grinding - screening - magnetic separation - flotation - acid leaching - washing - drying. In the process of purifying quartz sand by the above scheme, weakly magnetic impurity minerals such as hematite, ilmenite, limonite and biotite, as well as residual Fe-containing gas-liquid inclusions are likely to remain, resulting in a high level of residual Fe in the high-purity quartz sand, causing serious consequences such as color spots, high-temperature discoloration, high-temperature thermal deformation, and phase change crystallization in high-purity quartz products. In addition, it is difficult to specifically remove the gas-liquid inclusions in the quartz ore by the above scheme, and the residual inclusions will lead to problems such as high impurity content, excessive bubbles in quartz products, and decreased light transmittance.

[0004] In the prior art, CN116273393A discloses a high-purity quartz sand preparation process, and its specific process is: selecting, crushing, screening, washing, flotation to remove light impurities, acid washing to remove metal compounds, drying the crushed materials after washing, and finally putting the dried crushed materials into a magnetic separator for magnetic separation. The process is simple, but it is impossible to completely remove the residual iron-containing mineral impurities by magnetic separation alone, and the general magnetic separator is an open structure, which is easy to introduce additional impurities, causing pollution to the high-purity quartz sand again. Another Chinese patent with publication number CN102168173A discloses a method for extracting niobium from tailings, in which solid carbonaceous reducing agents such as nano-carbon powder, activated carbon, and charcoal are added to the crude niobium iron concentrate for microwave magnetization roasting to convert hematite into magnetite. The process introduces a solid reducing agent, and the residual reducing agent is easy to become a new impurity, which is not conducive to the further purification of quartz. Chinese patent document with publication number CN1562743A discloses a method for preparing ultrapure quartz sand, which uses cold explosion to increase longitude and latitude cracks to remove impurities inside the quartz sand. This process cannot effectively remove inclusions, and the low temperature of the cold explosion method consumes a lot of electricity and the operating environment is relatively dangerous. Summary of the invention

[0005] Therefore, the present invention provides a microwave magnetization roasting-gradient magnetic separation iron removal method and purification process for quartz ore. The method has simple procedures and extremely high impurity removal efficiency, and can specifically remove various weakly magnetic minerals and gas-liquid inclusions in quartz sand.

[0006] The specific technical solutions adopted are as follows:

[0007] A process for removing iron from granite pegmatite and purifying quartz comprises the following steps:

[0008] (1) Pretreatment: Manually select and remove visible impurities in the quartz ore, and then roast, water quench, filter, and dry the ore in sequence;

[0009] (2) Crushing and screening: The quartz ore treated in step (1) is subjected to crushing, grinding, sand making and screening in sequence to obtain coarse quartz sand;

[0010] (3) Microwave magnetization: The crude quartz sand obtained in step (2) is subjected to microwave magnetization roasting treatment in a microwave tube furnace under a reducing atmosphere to convert weakly magnetic impurity minerals into strongly magnetic minerals; at the same time, microwave heating is used to evaporate the Fe gas-liquid inclusions in the quartz sand at a specific temperature and convert them into magnetic substances; the characteristic of microwave selective heating also causes some gas-liquid inclusions to break under internal pressure, which is convenient for subsequent purification;

[0011] (4) Gradient magnetic separation: Gradient magnetic separation is used to remove various magnetic minerals and fine magnetic inclusions in the coarse sand after modification in step (3), and then scrubbing is performed;

[0012] (5) flotation: adding water to the quartz particles treated in step (4) to prepare a quartz sand slurry, adding a pH regulator and a flotation agent to the slurry to perform flotation operations;

[0013] (6) mixed acid leaching: adding the quartz sand obtained in step (5) into an acid leaching reactor, heating and stirring with the mixed acid solution to obtain refined quartz sand;

[0014] (7) High temperature chlorination: The quartz sand treated in step (6) is washed with deionized water until it becomes neutral and then centrifuged and dried. The quartz sand particles are then subjected to high temperature chlorination calcination treatment, purification and drying to obtain high purity quartz sand.

[0015] Preferably, in step (1), the SiO2 content in the quartz ore is not less than 10%.

[0016] Further preferably, in step (1), the quartz ore is roasted at a temperature of 800-1200° C. for 0.5-5 hours, then placed in cold water for water quenching, filtered, and dried, and finally the water content of the quartz particles is maintained below 5%.

[0017] Preferably, in step (2), coarse quartz sand with a mesh size of 50-160 is obtained after screening.

[0018] Preferably, in step (3), the microwave heating temperature is 600-1200°C, the heating time is 15-30 min, the reducing atmosphere is one or a mixture of H2, CH4 and CO, and the gas flow rate is 0.5-3.5 m 3 / min.

[0019] Preferably, in step (4), a gradient magnetic separation method combining permanent magnetic separation and superconducting magnetic separation is carried out, wherein the magnetic field strength of the permanent magnetic separation is 0.8-1.5T, the magnetic field strength of the superconducting magnetic separation is 2.0-5.0T, the medium for mechanical scrubbing is oxalic acid solution, the scrubbing time is 15-30min, and the scrubbing pulp concentration is 40-70%.

[0020] Preferably, in step (5), the pulp concentration is controlled to be 20-45% during flotation; the pH regulator is a mixture of one or more of sulfuric acid, hydrochloric acid or oxalic acid; the collector is one or more of sodium petroleum sulfonate, sodium dodecyl sulfonate, sodium dodecyl sulfate, sodium oleate or rosin amine; and the foaming agent is No. 2 oil.

[0021] Preferably, in step (6), the mixed acid solution used in the acid leaching is one or more of nitric acid, hydrochloric acid, oxalic acid, acetic acid and hydrofluoric acid, the concentrations of the nitric acid, hydrochloric acid, oxalic acid, acetic acid and hydrofluoric acid used are all 15-25%, and the solid-to-liquid ratio of the mixed solution of the quartz sand and the acid solution is 1:1 to 1:3.

[0022] Preferably, in step (7), the high-temperature chlorination calcination temperature is controlled at 800°C-1000°C, and a chlorinating agent is added during the high-temperature calcination, wherein the chlorinating agent comprises one or a combination of sodium chloride, calcium chloride, hydrogen chloride and chlorine.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] In order to solve the problem that impurity elements such as Fe and various inclusions are difficult to remove in the existing process, the microwave magnetization roasting method is used to carry out magnetic modification of natural ores. The reducing atmosphere gas in the microwave tube furnace can fully contact with the quartz sand, while avoiding the risk of mixing with solid impurities. In the unique environment of reducing microwave roasting, a series of reactions occur simultaneously: the hematite Fe2O3 in the quartz sand is reduced to magnetite Fe3O4; the ilmenite FeTiO3 is decomposed into Fe, TiO2 and H2O, and then Fe reacts with the hematite Fe2O3 to generate magnetite Fe3O4; the limonite Fe2O3·nH2O is dehydrated to hematite Fe2O3 and then reduced to magnetite Fe3O4; even the complex biotite K(Mg,Fe)3AlSi3O 10 (F,OH)2 can also be converted into magnetic substances under the action of reducing microwave roasting; and some Fe-containing gas-liquid inclusions are converted into fine magnetic inclusions. Then, through the gradient magnetic separation process combining permanent magnet and superconducting magnetic separation, the Fe-containing magnetic minerals and fine magnetic inclusions are accurately separated and removed, thereby obtaining low-iron high-purity quartz sand. Due to the characteristics of microwave selective heating, gas-liquid inclusions are more likely to expand and rupture, and the difference in expansion coefficients between mineral inclusions and quartz sand easily generates huge thermal stress at the interface, which will cause the mineral inclusions to expand and rupture, produce cracks, and release impurities, which effectively improves the efficiency of subsequent acid leaching and impurity removal. The purity of the obtained quartz sand can exceed 99.9985%, and the Fe element can be as low as 0.04ppm. In addition, the efficient impurity removal using microwave magnetic roasting-gradient magnetic separation can greatly reduce the frequency of subsequent use of various acid solutions and flotation agents, greatly simplify high-pollution processes, and be more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present application provides a process flow chart of the microwave magnetic roasting-gradient magnetic separation iron removal method and purification process for quartz ore.

[0026] Figure 2 Schematic diagram of Fe-containing gas-liquid inclusions inside quartz sand before and after microwave magnetization roasting. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The present invention will be further described below in conjunction with specific implementation modes.

[0029] To maintain the consistency of the experiments, the natural quartz ore sources used in the following Examples 1 to 7 are all of the same quality stable imported quartz ore from India, the type is granite pegmatite, and the quartz content in the original ore is about 15-25%.

[0030] Example 1

[0031] (1) Pretreatment: Manually select and remove visible impurities in the ore, place the selected quartz ore in a tunnel kiln at 1050°C for 4 hours of roasting, place the quartz ore in cold water for quenching after roasting, and filter and dry after complete cooling;

[0032] (2) Crushing and screening: The pretreated quartz ore is crushed, ground, sanded, and screened to obtain 50-160 mesh coarse quartz sand, which is washed with deionized water, filtered under reduced pressure, and then dried to finally keep the water content of the quartz particles below 5% to obtain coarse quartz sand;

[0033] (3) Gradient magnetic separation: various magnetic minerals in the crude quartz sand obtained in step (2) are removed by permanent magnetic separation, the magnetic field strength of the permanent magnetic separation is 1.4 T, and then the quartz sand after magnetic separation is mechanically scrubbed, the scrubbing medium is oxalic acid solution, the scrubbing time is 20 minutes, and the scrubbing pulp concentration is 50%;

[0034] (4) flotation: the scrubbed pulp obtained in step (3) is rinsed and filtered, and then adjusted to a 30% quartz sand slurry, which is added to a flotation machine for flotation operation, oxalic acid is added to the pulp to adjust the pH value to 3.0, and a collector composed of sodium dodecyl sulfate, sodium oleate, and rosin amine is added. The amount of the collector added is 150 g / t. After stirring to generate a small amount of foam, 120 g / t of a foaming agent No. 2 oil is added thereto, stirred, and the foam is scraped and floated for 10 minutes;

[0035] (5) mixed acid leaching: the quartz sand obtained after flotation in step (4) is cleaned and added into a reactor for atmospheric pressure acid leaching, stirred and reacted at 80°C for 6 hours, and then repeatedly washed with deionized water until neutral, wherein the mixed acid solution is prepared by mixing 36% concentrated hydrochloric acid, 68% concentrated nitric acid and 98% concentrated sulfuric acid in a volume ratio of 8:2:1, the concentration of the acid solution is 25%, and the solid-liquid ratio of the mixed solution of quartz sand and the acid solution is 1:2;

[0036] (6) High-temperature chlorination: The quartz sand treated in step (5) is washed with pure water until it becomes neutral and then centrifuged and dried. The quartz sand particles are then subjected to high-temperature chlorination calcination treatment. After HCl gas is introduced, the reaction is carried out at 900° C. for 2 h. Sodium chloride is added as an auxiliary chlorination agent during the high-temperature calcination to obtain high-purity quartz sand.

[0037] The content of impurity elements in the high-purity quartz sand obtained in Example 1 was analyzed by ICP-OES. The results are shown in Table 1. The total amount of impurity elements was 33.43 ppm, of which the Fe element content was 2.64 ppm.

[0038] Example 2

[0039] like Figure 1 As shown, this embodiment provides a microwave magnetization roasting-gradient magnetic separation iron removal method and purification process for quartz ore.

[0040] (1) Pretreatment: Manually select and remove visible impurities in the ore, place the selected quartz ore in a tunnel kiln at 1050°C for 4 hours of roasting, place the quartz ore in cold water for quenching after roasting, and filter and dry after complete cooling;

[0041] (2) Crushing and screening: The pretreated quartz ore is crushed, ground, sanded, and screened to obtain 50-160 mesh coarse quartz sand, which is washed with deionized water, filtered under reduced pressure, and then dried to finally keep the water content of the quartz particles below 5% to obtain coarse quartz sand;

[0042] (3) Microwave magnetization: The crude quartz sand was subjected to microwave magnetization roasting treatment in a microwave tube furnace under a reducing atmosphere. The microwave tube furnace was set at a temperature of 700°C and a heating time of 15 min. The reducing atmosphere was H2 and the gas flow rate was 1.5 m / s. 3 / min;

[0043] (4) Gradient magnetic separation: permanent magnetic separation is used to remove various magnetic minerals in the coarse quartz sand. The magnetic field strength of the permanent magnetic separation is 1.4T. The quartz sand after magnetic separation is then mechanically scrubbed. The scrubbing medium is oxalic acid solution. The scrubbing time is 20 minutes and the scrubbing pulp concentration is 50%;

[0044] (5) Flotation: The scrubbed pulp is rinsed and filtered, and then adjusted to 30% quartz sand slurry, which is added to a flotation machine for flotation. Oxalic acid is added to the pulp to adjust the pH value to 3.0, and a collector consisting of sodium dodecyl sulfate, sodium oleate, and rosin amine is added. The amount of the collector added is 150 g / t. After stirring to generate a small amount of foam, 120 g / t of frother No. 2 oil is added, stirred, and flotation is performed for 10 minutes by scraping foam;

[0045] (6) Mixed acid leaching: After the quartz sand after flotation is cleaned, it is added into a reactor for atmospheric pressure acid leaching treatment, stirred and reacted at 80°C for 6 hours, and then repeatedly washed with deionized water until neutral, wherein the mixed acid solution is prepared by mixing 36% concentrated hydrochloric acid, 68% concentrated nitric acid and 98% concentrated sulfuric acid in a volume ratio of 8:2:1, the concentration of the acid solution is 25%, and the solid-liquid ratio of the mixed solution of quartz sand and acid solution is 1:2;

[0046] (7) High-temperature chlorination: The quartz sand treated in step (5) is washed with pure water until it becomes neutral and then centrifuged and dried. The quartz sand particles are then subjected to high-temperature chlorination calcination treatment. After HCl gas is introduced, the reaction is carried out at 900° C. for 2 h. Sodium chloride is added as an auxiliary chlorination agent during the high-temperature calcination to obtain high-purity quartz sand.

[0047] The content of impurity elements in the high-purity quartz sand obtained in this Example 2 was analyzed by ICP-OES. The results are shown in Table 1. The purity of the high-purity quartz sand reached 4N8 level, the total amount of impurity elements was 19.88 ppm, of which the Fe content was 1.88 ppm. Compared with Example 1, Example 2 added a microwave magnetization roasting process, and the results showed that the impurity elements such as Fe, Al, and Na were significantly reduced.

[0048] Example 3

[0049] Except that the microwave tube furnace temperature was set to 950° C., the other steps were consistent with the experimental steps and methods of Example 2, and the same method was used for characterization, and the impurity content results of the quartz sand were shown in Table 1.

[0050] The content of impurity elements in the high-purity quartz sand obtained in this Example 3 was analyzed by ICP-OES. The results are shown in Table 1. The total amount of impurity elements is 14.17 ppm, of which the Fe content is 1.35 ppm. Compared with Example 2, Example 3 increases the microwave magnetization roasting process to 900°C. The results show that impurity elements such as Fe, Al, and Na are significantly reduced, which is related to the valence state transformation of Fe-containing inclusions / impurity minerals at higher temperatures and the high-temperature rupture of more inclusions.

[0051] Example 4

[0052] (1) Pretreatment: Manually select and remove visible impurities in the ore, place the selected quartz ore in a tunnel kiln at 1050°C for 4 hours of roasting, place the quartz ore in cold water for quenching after roasting, and filter and dry after complete cooling;

[0053] (2) Crushing and screening: The pretreated quartz ore is crushed, ground, sanded, and screened to obtain 50-160 mesh coarse quartz sand, which is washed with deionized water, filtered under reduced pressure, and then dried to finally keep the water content of the quartz particles below 5% to obtain coarse quartz sand;

[0054] (3) Microwave magnetization: The crude quartz sand was subjected to microwave magnetization roasting treatment in a microwave tube furnace under a reducing atmosphere. The microwave tube furnace was set at a temperature of 950°C and a heating time of 15 min. The reducing atmosphere was H2 and the gas flow rate was 1.5 m / s. 3 / min;

[0055] (4) Gradient magnetic separation: A gradient magnetic separation method combining permanent magnetic separation and superconducting magnetic separation is used, wherein the magnetic field strength of the permanent magnetic separation is 1.4T, and the magnetic field strength of the superconducting magnetic separation is 2.0T. The quartz sand after magnetic separation is then mechanically scrubbed with an oxalic acid solution for 20 minutes. The scrubbing pulp concentration is 50%;

[0056] (5) Flotation: The scrubbed pulp is rinsed and filtered, and then adjusted to 30% quartz sand slurry, which is added to a flotation machine for flotation. Oxalic acid is added to the pulp to adjust the pH value to 3.0, and a collector consisting of sodium dodecyl sulfate, sodium oleate, and rosin amine is added. The amount of the collector added is 150 g / t. After stirring to generate a small amount of foam, 120 g / t of frother No. 2 oil is added, stirred, and flotation is performed for 10 minutes by scraping foam;

[0057] (6) Mixed acid leaching: After the quartz sand after flotation is cleaned, it is added into a reactor for atmospheric pressure acid leaching treatment, stirred and reacted at 80°C for 6 hours, and then repeatedly washed with deionized water until neutral, wherein the mixed acid solution is prepared by mixing 36% concentrated hydrochloric acid, 68% concentrated nitric acid and 98% concentrated sulfuric acid in a volume ratio of 8:2:1, the concentration of the acid solution is 25%, and the solid-liquid ratio of the mixed solution of quartz sand and acid solution is 1:2;

[0058] (7) High-temperature chlorination: The quartz sand treated in step (5) is washed with pure water until it becomes neutral and then centrifuged and dried. The quartz sand particles are then subjected to high-temperature chlorination calcination treatment. After HCl gas is introduced, the reaction is carried out at 900° C. for 2 h. Sodium chloride is added as an auxiliary chlorination agent during the high-temperature calcination to obtain high-purity quartz sand.

[0059] The content of impurity elements in the high-purity quartz sand obtained in this Example 4 was analyzed by ICP-OES. The results are shown in Table 1. The total amount of impurity elements is 12.32 ppm, of which the Fe content is 0.77 ppm. Compared with Example 3, Example 4 adds superconducting magnetic separation on the basis of microwave magnetization roasting process. The results show that the impurity elements such as Fe, Al, and Ti are significantly reduced. This is due to the mineral processing effect of magnetic modification of impurity minerals / inclusions and superconducting magnetic separation.

[0060] Example 5

[0061] Except that the magnetic field strength of the superconducting magnetic separation is adjusted to 3.0 T, the other steps are consistent with the experimental steps and methods of Example 4, and the same method is used for characterization, and the impurity content results of the quartz sand are shown in Table 1.

[0062] The content of impurity elements in the high-purity quartz sand obtained in this Example 5 was analyzed by ICP-OES. The results are shown in Table 1. The total amount of impurity elements is 11.59 ppm, of which the Fe element content is 0.39 ppm. Compared with Example 4, Example 5 increases the magnetic field intensity of superconducting magnetic separation from 2.0 T to 3.0 T, and cooperates with microwave magnetization calcination to further reduce the Fe impurity element.

[0063] Example 6

[0064] Except that the magnetic field intensity of the superconducting magnetic separation is adjusted to 4.0 T, the other steps are consistent with the experimental steps and methods of Example 4, and the same method is used for characterization, and the impurity content results of the quartz sand are shown in Table 1.

[0065] The impurity element content in the high-purity quartz sand of this Example 6 was analyzed by ICP-OES. The total amount of impurity elements was 11.32 ppm, of which the Fe element content was 0.18 ppm.

[0066] Example 7

[0067] Except that the magnetic field intensity of the superconducting magnetic separation is adjusted to 5.0 T, the other steps are consistent with the experimental steps and methods of Example 4, and the same method is used for characterization, and the impurity content results of the quartz sand are shown in Table 1. Figure 2 The changes of Fe-containing gas-liquid inclusions in high-purity quartz sand before and after microwave magnetization roasting at 950°C are demonstrated. After microwave magnetization roasting, the Fe-containing gas-liquid inclusions are heated and decomposed into solid matter, and acquire magnetic properties, which are targetedly removed in the subsequent magnetic separation process.

[0068] The content of impurity elements in the high-purity quartz sand obtained in Example 7 was analyzed by ICP-OES. The results are shown in Table 1. The total amount of impurity elements is 10.07 ppm, of which the Fe content is 0.04 ppm. This means that the Fe element that remains in various forms (fine mineral impurities, fine gas-liquid inclusions) and is difficult to remove is removed by the microwave magnetization roasting process combined with the gradient magnetic separation of permanent magnet-high-intensity superconducting wet magnetism. At the same time, other impurity elements combined with Fe are removed. In combination with other purification steps, the natural quartz ore is processed into high-quality, high-value-added high-purity quartz sand, which meets the standard of high-purity quartz sand for photovoltaics (Fe≤0.5ppm, GB / T 32649-2016 High-purity quartz sand for photovoltaics).

[0069] Sample analysis

[0070] The impurity content of the quartz sand products obtained in the examples and comparative examples was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES). The results are shown in Table 1.

[0071] Table 1 Impurity content in the product quartz sand in the embodiment (ppm)

[0072] project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Al 16.03 9.51 6.03 5.96 5.82 5.97 5.61 B 0.20 0.15 0.13 0.14 0.14 0.13 0.13 Ba 0.05 0.05 0.03 0.04 0.03 0.03 0.03 Ca 3.85 2.24 1.99 1.37 1.29 1.18 0.91 Cr 0.01 0.03 0.02 0.02 0.01 0.02 0.02 Cu 0.07 0.05 0.01 0.01 0.01 0.00 0.00 Fe 2.64 1.88 1.35 0.77 0.39 0.18 0.04 Ge 0.58 0.72 0.74 0.71 0.71 0.69 0.57 K 0.73 0.38 0.05 0.05 0.10 0.07 0.03 Li 0.42 0.44 0.33 0.31 0.30 0.31 0.30 Mg 0.49 0.23 0.08 0.06 0.06 0.09 0.05 Mn 0.03 0.03 0.01 0.00 0.01 0.01 0.01 Na 1.96 0.71 0.17 0.18 0.20 0.31 0.22 Ni 0.02 0.04 0.01 0.02 0.00 0.01 0.02 P 0.92 0.75 0.76 0.60 0.55 0.44 0.64 Ti 4.97 2.42 2.44 2.05 1.94 1.85 1.42 Zr 0.46 0.25 0.02 0.03 0.03 0.03 0.07 ∑ 33.43 19.88 14.17 12.32 11.59 11.32 10.07

[0073] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A microwave magnetization roasting-gradient magnetic separation iron removal method and purification process for quartz ore, It is characterized in that First, the raw ore is crushed, ground, and sanded to obtain coarse quartz sand particles; then, the quartz sand is subjected to microwave magnetization roasting in a microwave tube furnace under a reducing atmosphere to convert weakly magnetic impurity minerals into strongly magnetic minerals; at the same time, microwave heating is used to evaporate the Fe gas-liquid inclusions in the quartz sand at a specific temperature and convert them into magnetic substances; the characteristics of microwave selective heating also cause some gas-liquid inclusions to break under internal pressure; then gradient magnetic separation is carried out to remove various magnetic impurity minerals using permanent magnets and to remove fine magnetic inclusions in the quartz sand using superconducting magnetic separation; finally, the quartz sand is subjected to flotation, acid leaching, and chlorination purification treatment to finally obtain high-grade low-iron quartz sand, which specifically includes the following steps: (1) Pretreatment: Manually select and remove visible impurities in the quartz ore, and then roast, water quench, filter, and dry the ore in sequence; (2) Crushing and screening: The quartz ore treated in step (1) is subjected to crushing, grinding, sand making and screening in sequence to obtain coarse quartz sand; (3) Microwave magnetization: The crude quartz sand obtained in step (2) is subjected to microwave magnetization roasting treatment in a microwave tube furnace under a reducing atmosphere; (4) Gradient magnetic separation: using gradient magnetic separation to remove various magnetic minerals and fine magnetic inclusions in the coarse sand modified in step (3), and then scrubbing; (5) flotation: adding water to the quartz particles treated in step (4) to prepare a quartz sand slurry, adding a pH regulator and a flotation agent to the slurry to perform flotation operations; (6) mixed acid leaching: adding the quartz sand obtained in step (5) into an acid leaching reactor, heating and stirring with a mixed acid solution to obtain refined quartz sand; (7) High-temperature chlorination: The quartz sand treated in step (6) is washed with deionized water until it becomes neutral, centrifuged and dried, and then the quartz sand particles are subjected to high-temperature chlorination roasting treatment to obtain high-purity quartz sand.

2. The microwave magnetization roasting-gradient magnetic separation iron removal method and purification process of quartz ore according to claim 1, It is characterized in that In step (1), the SiO 2 The content is not less than 10%.

3. The microwave magnetization roasting-gradient magnetic separation iron removal method and purification process of quartz ore according to claim 1, It is characterized in that In step (1), the ore is roasted at a temperature of 800° C. to 1200° C. for 0.5-5 hours, then placed in cold water for water quenching, filtered, and dried, and finally the water content of the quartz particles is maintained below 5%.

4. The microwave magnetization roasting-gradient magnetic separation iron removal method and purification process of quartz ore according to claim 1, It is characterized in that In step (2), coarse quartz sand with a mesh size of 50-160 is obtained after screening.

5. The microwave magnetization roasting-gradient magnetic separation iron removal method and purification process of quartz ore according to claim 1, It is characterized in that In step (3), the crude quartz sand is subjected to microwave magnetization treatment in a reducing atmosphere using a microwave tube furnace, the microwave heating temperature is 600-1200° C., the heating time is 15-30 min, and the reducing atmosphere is H 2 , CH 4 Mixed with one or more of CO, the gas flow rate is 0.5-3.5m 3 / min.

6. The microwave magnetization roasting-gradient magnetic separation iron removal method and purification process of quartz ore according to claim 1, It is characterized in that In step (4), a gradient magnetic separation method combining permanent magnetic separation and superconducting magnetic separation is performed, wherein the magnetic field strength of the permanent magnetic separation is 0.8-1.5T, the magnetic field strength of the superconducting magnetic separation is 2.0-5.0T, and the quartz sand after magnetic separation is mechanically scrubbed, the scrubbing medium is oxalic acid solution, the scrubbing time is 15-30min, and the scrubbed slurry concentration is 40-70%.

7. The microwave magnetization roasting-gradient magnetic separation iron removal method and purification process of quartz ore according to claim 1, It is characterized in that In step (5), the pulp concentration is controlled to be 20-45% during flotation; the pH regulator is one or a mixture of sulfuric acid, hydrochloric acid and oxalic acid; the collector is one or a mixture of sodium petroleum sulfonate, sodium dodecyl sulfonate, sodium dodecyl sulfate, sodium oleate or rosin amine; and the foaming agent is No. 2 oil.

8. The microwave magnetization roasting-gradient magnetic separation iron removal method and purification process of quartz ore according to claim 1, It is characterized in that In step (6), the mixed acid solution used in the acid leaching is one or a mixture of nitric acid, hydrochloric acid, oxalic acid, acetic acid and hydrofluoric acid, the concentration of the nitric acid, hydrochloric acid, oxalic acid, acetic acid and hydrofluoric acid used is 15-25%, the solid-liquid ratio of the mixed solution of quartz sand and the acid solution is 1:1-1:3, the leaching temperature is 70-85°C, and the heating and stirring time is 2-6h.

9. The microwave magnetization roasting-gradient magnetic separation iron removal method and purification process of quartz ore according to claim 1, It is characterized in that In step (7), the high-temperature chlorination calcination temperature is controlled at 800° C.-1000° C., and a chlorinating agent is added during the high-temperature calcination. The chlorinating agent comprises one or a combination of sodium chloride, calcium chloride, hydrogen chloride and chlorine.

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