Method for preparing 4N-grade high-purity quartz by purifying Shiwu-series powder quartz

Abstract

The invention discloses a method for preparing 4N-grade high-purity quartz by purifying Shiwui-series powder quartz. The method comprises the following steps: carrying out coupling scrubbing on raw ore and a synergistic dispersant; settling and removing-400-mesh fine silt, extracting silicon and reducing impurities; iron-containing minerals are removed through strong magnetic separation, and magnetic substances and non-magnetic substances are obtained; screening non-magnetic substances to remove coarse particles of + 40 meshes; carrying out reverse flotation on non-magnetic substances with the size of-40 + 400 meshes by using a new reagent to remove feldspar and other black impurity minerals so as to obtain flotation concentrate; -40 + 80-mesh coarse particles are screened out from flotation concentrate, acid pickling, calcination, water quenching and acid pickling are conducted, and 4N-grade high-purity quartz concentrate is obtained; fine particles of-80 + 400 meshes are screened out from flotation concentrate, primary acid pickling is conducted, and 3N7-grade secondary high-purity quartz concentrate is obtained; fine silt, magnetic substances, + 40-mesh coarse particles and flotation middlings can be used as aerated bricks and novel building materials. The method provided by the invention realizes stepped high-valued utilization of the Shiwui-series powder quartz resource, greatly improves the economic value and social benefit, and is also suitable for purification of other types of powder quartz.

Description

Technical Field

[0001] The present invention belongs to the technical field of deep processing of non-metallic minerals. Specifically, it relates to a method for purifying Cambrian powder quartz to prepare 4N grade high-purity quartz. Background Art

[0002] With the rapid development of technology, high-purity quartz has become an irreplaceable key material in high-tech fields such as semiconductors, photovoltaics, and new energy. Powder quartz is a natural quartz mineral resource formed under natural weathering, leaching, and disintegration. It looks like earthy. It occurs naturally in powder form, with a loose structure and can be easily crushed into powder by gently squeezing in the dry state. After being contaminated by iron, mud, etc., it shows red or yellowish-brown color. High-purity quartz concentrate can be obtained through purification treatment. Powder quartz has a fine natural particle size, a relatively regular particle shape, and an aspect ratio close to 1:1, and is regarded as a high-quality industrial silica raw material. After traditional massive quartz resources are crushed and ground, needle-shaped raw materials are easily formed. When producing quartz glass, the needle-shaped raw materials are likely to cause blockage of the feeding channel. At the same time, processing massive quartz resources requires a crushing and grinding process, and the grinding cost is high. Therefore, it is of great significance to carry out high-value purification research on powder quartz.

[0003] The main difficulty in purifying powder quartz is that the original powder quartz ore is a weathered fine-grained ore. The weathering process forms inert impurities or disseminated impurities on the surface or in the cracks of the powder quartz particles, which are extremely difficult to remove. At the same time, during the mineralization or mining process, coexisting silicate mineral clay impurities with extremely fine particle size and physical and chemical properties extremely similar to those of powder quartz particles, as well as a small amount of inclusion impurities and lattice impurities are mixed in. The inclusion impurities mostly exist inside the quartz particles in the form of <10μm. Different types and contents of impurities seriously affect the performance of downstream quartz products, making the purification of powder quartz much more difficult than that of hard-rock type quartz ore. Although the original powder quartz ore has poor quality and fine particle size, with the progress of the purification process, powder quartz can still enter the high-end quartz product industry.

[0004] In recent years, large-scale high-quality amorphous silica resources have been successively discovered in many regions of China, such as Guangxi, Jiangxi, and Guizhou. The SiO2 content of the raw ore of the amorphous silica ore in Jiangxi is 99%, and the whiteness is relatively high. Its resource reserves and annual output rank first in the country, attracting the research interest of many scientific researchers. High-purity quartz generally requires a SiO2 content of more than 99.9% and an Fe2O3 content of less than 10 μg / g (Fe content less than 7 μg / g). Since the amorphous silica has a fine particle size, the crushing and grinding processes can be omitted, greatly reducing the purification cost. Therefore, purifying and preparing 4N-grade high-purity quartz from the abundant amorphous silica resources can change the current situation of poor utilization of high-quality resources and realize greater resource value for amorphous silica. At present, the purification technologies of amorphous silica mainly include physical methods and chemical methods. The physical methods mainly aim to remove most of the clay impurities or associated mineral impurities, including scrubbing and de-sludging, gravity classification, magnetic separation, and flotation. The chemical methods include roasting, acid leaching, chlorination, etc.

[0005] Tang Chunhua et al. (Patent No. CN202311552681.8) announced a process for purifying and processing 4N-grade high-purity fine-grained quartz sand from natural amorphous silica. Using Jiangxi amorphous silica (raw ore SiO2 content 99.08%, Al2O3 content 0.49%, Fe2O3 content 0.075%), a combination of physical and chemical purification methods such as screening - magnetic separation - flotation - calcination - acid leaching was adopted, and finally a high-purity quartz concentrate with a SiO2 content of 99.992% was obtained. The amorphous silica raw material used in this invention has good quality and relatively high whiteness. The raw ore SiO2 has reached 99%, and the iron and aluminum contents are both very low, laying a good foundation for purifying and preparing high-purity quartz concentrate.

[0006] Wu Zhaoyang et al. selected an amorphous silica ore in a certain place in Jiangxi as the raw material (Research on the beneficiation and purification technology of Jiangxi amorphous silica, "China Non-Metallic Minerals Industry Herald", No. 4, 2011). The raw ore SiO2 content is 97.90%, the Al2O3 content is 1.15%, and the TFe content is 0.024%. Through treatment processes such as scrubbing, classification and de-sludging, magnetic separation, flotation, acid washing, and calcination, silicon micropowder with a SiO2 content ≥99.93%, low iron, aluminum and other impurity contents, and meeting the requirements for use in the electronics and electrical industries was obtained. The purification process used calcination and acid washing, and the quartz purity only reached 3N, still having room for further improvement.

[0007] Du Jie et al. (Patent No. CN201910724769.0) announced a beneficiation and purification method for incompletely weathered silica powder. Using Guangxi silica powder (the original ore contains 94.32% SiO2, 2.15% Al2O3, and 0.043% Fe2O3), physical purification methods such as scrubbing - screening - selective flocculation - reverse flotation were adopted, and finally quartz concentrate with only 99.2% SiO2 content was obtained. The quartz purity is relatively low and there is room for further improvement.

[0008] Luo Shaodong et al. took five kinds of silica powder ores produced in Qiannan Prefecture as the research object (Study on the Characteristics and Processing Technology of Silica Powder in Qiannan Prefecture, Guizhou, "Mineral Resources Protection and Utilization", No. 2, 2013). The original ore contains 95.3% - 98% SiO2. Water washing and acid leaching methods were used for purification. After acid washing and purification, the SiO2 content is above 99.30%. Although chemical purification was used, the final SiO2 purity only reached 2N, and the added value of the quartz concentrate product is relatively low and needs to be further improved.

[0009] As can be seen from the above, current research results on the purification of silica powder mainly focus on the preparation of silica powder with 99% and 99.9% SiO2 content. There is still a lack of effective separation methods for the preparation of 99.99% high - purity quartz.

[0010] Recently, a large - reserve and previously unreported silica powder deposit was discovered in the southern Cambrian system in Tongren, Guizhou, China. This type of deposit is a typical weathering and leaching - type deposit, mainly loose accumulation. Under the combined action of external forces such as wind, tides, and coastal currents, the detrital materials are repeatedly washed and accumulated to form a quartz sand layer, which appears red due to a high mud content. The original ore of Guizhou silica powder contains 65.48% - 95.10% SiO2, with an average grade of 82.95%, 1.4% - 15.64% Al2O3, and 0.56% - 7.06% Fe2O3. The rock components mainly consist of quartz, siliceous debris, clay minerals, iron oxides, etc. The ore structure is mainly unequal - grain sand - like structure and microcrystalline - fine - crystalline structure; the ore texture is mainly fractured texture and massive texture. The selected sample of Jiangxi silica powder contains about 99% SiO2, about 0.5% Al2O3, and less than 0.1% Fe2O3 (Patent CN202311552681.8). Obviously, Guizhou silica powder and Jiangxi silica powder are of different types and qualities. Guizhou silica powder is red, while Jiangxi silica powder is white. The silicon content of the original ore of Jiangxi silica powder is much higher than that of Guizhou. It is extremely difficult to purify and prepare 4N - grade high - purity quartz from the Cambrian silica powder in Guizhou. There is no relevant literature or patent reporting the successful preparation of 4N - grade high - purity quartz. Therefore, the 4N - grade purification technology for this Cambrian silica powder is still blank.

[0011] In view of this, the present invention is specifically proposed. Summary of the Invention

[0012] In order to change the current situation of poor utilization of high-quality resources of Cambrian powder quartz, the present invention provides a method for purifying and preparing 4N grade high-purity quartz from powder quartz raw ore by coupling dispersant scrubbing - sedimentation de-sludging - magnetic separation - screening - flotation - classification - pickling - calcination water quenching - pickling. This method introduces dispersant coupling scrubbing to fully cleave and disperse powder quartz and fine-grained clay particles, remove clay minerals and disseminated iron minerals to a greater extent, achieve efficient separation of concentrate and clay pulp, effectively improve the silicon quality and reduce iron and aluminum impurities, and then use a collector with good selectivity and excellent synergistic effect to remove feldspar and other black impurity minerals in the powder quartz, realizing deep separation of powder quartz from various impurities, laying a foundation for the later preparation of high-purity quartz by calcination and acid leaching chemical purification. The present invention can greatly improve the application range and economic benefits of Cambrian powder quartz ore.

[0013] To solve the above technical problems, the basic concept of the technical solution adopted in the present invention is:

[0014] A method for purifying and preparing 4N grade high-purity quartz from Cambrian powder quartz includes the following steps:

[0015] Step 1, raw ore coupling dispersant scrubbing: Using Cambrian powder quartz as the selected raw ore, adding a dispersant and water, and scrubbing and stirring in a scrubbing machine to obtain a scrubbed pulp;

[0016] Step 2, sedimentation de-sludging: Pouring the scrubbed pulp obtained in Step 1 into a graduated cylinder, fully stirring and gravity sedimenting to remove the slime, and repeating this process multiple times for de-sludging until the supernatant is clear, obtaining quartz coarse sand and slime;

[0017] Step 3, high-intensity magnetic separation: Performing high-intensity magnetic separation on the quartz coarse sand material obtained in Step 2 to obtain magnetic substances and non-magnetic substances;

[0018] Step 4, screening: Screening the non-magnetic substances obtained in Step 3 to remove +40 mesh coarse particles, and increasing the silicon content in the -40 + 400 mesh particle size;

[0019] Step 5, reverse flotation: Pouring the -40 + 400 mesh non-magnetic substances obtained in Step 4 into a flotation machine, adjusting the pulp pH, adding a collector, and performing reverse flotation multiple times to obtain flotation concentrate and middlings;

[0020] Step 6, pickling: Screening out the coarse particles -40 + 80 mesh from the flotation concentrate obtained in Step 5 for pickling and ultrasonic cleaning to obtain acid leaching concentrate;

[0021] Step 7, calcination water quenching - pickling: Calcining - water quenching - pickling the acid leaching concentrate obtained in Step 6 to obtain 4N grade high-purity quartz concentrate;

[0022] Step 8, pickling: Screening out the -80 + 400 mesh fine particles from the flotation quartz concentrate obtained in Step 5 for one-time pickling to prepare 3N7 grade sub-high-purity quartz concentrate;

[0023] Among them, the slime obtained in step 2, the magnetic substance obtained in step 3, the +40 mesh coarse particles obtained in step 4, and the middlings in flotation obtained in step 5 can be used to make aerated bricks and new building materials.

[0024] The flotation collector is a mixture of compound amine, fatty acid, and silicate inhibitor; among them, the weight percentage of compound amine, fatty acid, and silicate inhibitor is 7:7:1;

[0025] The screening of +40 mesh coarse particles can be carried out on the coarse sand obtained in step 2 or on the non-magnetic substance obtained in step 3.

[0026] The flotation concentrate obtained in step 5 is screened to separate out -40 + 80 mesh coarse particles and -80 + 400 mesh fine particles. It can also be screened into other particle sizes such as -40 + 100 mesh and -100 + 400 mesh, etc. High-purity quartz concentrates with different grades and particle sizes can be prepared according to market demand.

[0027] Preferably, in step 1, the dispersant is one or a mixture of two of silicate, inorganic strong base, and long-chain inorganic alkali metal phosphate.

[0028] Preferably, in step 2, sedimentation and slime removal are carried out by pumping once every 5 minutes, with the number of pumping times being 10 - 14 times, removing the fine slime below 400 mesh until the pulp is clarified.

[0029] Preferably, in step 3, high-intensity magnetic separation is wet magnetic separation, and the magnetic separation operation includes one-stage magnetic separation with a magnetic field intensity of 1.4 - 2.0 T.

[0030] Preferably, in step 4, the screening is carried out with a 40-mesh standard sieve, separating into +40 mesh coarse particles and -40 + 400 mesh fine particles. The +40 mesh coarse particles do not meet the particle size requirements of high-purity quartz and have a high impurity content.

[0031] Preferably, in step 5, reverse flotation is pneumatic flotation, and the process conditions are as follows: the pulp concentration is 10 - 30%, the pulp pH is 2 - 3, the acid used to adjust the pulp is one or a mixture of sulfuric acid and hydrofluoric acid, the dosage of the collector is 300 - 600 g / t, the stirring rate is 1200 - 1500 r / min, the flotation time is 1 - 2 min, and multiple flotation operations are carried out until all impurities are removed.

[0032] Preferably, in step 6, the -40 + 80 mesh coarse particles separated from the flotation quartz concentrate are pickled. The mixed acid is a mixture of nitric acid, hydrochloric acid, and hydrofluoric acid, the leaching time is 4 - 24 hours, and ultrasonic cleaning is carried out.

[0033] Preferably, in step 7, the acid-leached concentrate is calcined in a muffle furnace at 1050°C for 1 hour, water-quenched, pickled, the mixed acid is a mixture of nitric acid, hydrochloric acid, and hydrofluoric acid, the leaching time is 4 to 24 hours, and ultrasonic cleaning is performed to obtain 4N grade high-purity quartz concentrate.

[0034] Preferably, in step 8, the -80 + 400 mesh fine particles of the flotation quartz concentrate are directly subjected to primary pickling, the leaching time is 4 to 24 hours, and ultrasonic cleaning is performed to obtain 3N7 grade sub-high-purity quartz concentrate;

[0035] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0036] Combined with the XRD analysis, microscopic identification, and laser Raman spectroscopy analysis of Guizhou chalcedony, it can be known that the main impurity sources of iron and aluminum are kaolinite, hematite, and feldspar. The size of the rich liquid-phase inclusions and pure gas-phase inclusions in the original chalcedony ore is <5μm, and the size of the solid inclusions is <10μm. Among them, the liquid-phase component in the rich liquid-phase inclusions is mainly H2O, and the components of the pure gas-phase inclusions are mainly C2H4, C3H8, C6H6, and aromatic hydrocarbon gases. The small size of the inclusions and the long-term weathering and clay impurity impregnation greatly increase the purification difficulty. The key of the present invention is to adopt the dispersant-coupled scrubbing and dispersion de-sludging process, which has a low treatment cost and can remove the fine-grained clay minerals and impregnated iron minerals on the surface of the chalcedony particles to a greater extent, greatly improving the silicon quality and reducing the impurity contents such as iron and aluminum. After de-sludging, the quality of the chalcedony has a qualitative leap. The SiO2 grade of the quartz sand is increased from 92.39% of the original ore to 99.58%, Al2O3 is reduced from 3.41% of the original ore to 0.25%, the aluminum removal rate is 92.6%, Fe2O3 is reduced from 1.66% of the original ore to 0.095%, and the iron removal rate is 94.2%. The quality of the chalcedony is greatly improved.

[0037] Through the synergistic effect of the new agents, the present invention further removes feldspar and black impurity minerals in the chalcedony, realizes the efficient and deep separation of chalcedony and various impurities, greatly improves the purity of the flotation quartz concentrate, and lays a foundation for the later calcination and acid leaching purification to prepare high-purity quartz. The novel flotation agents are all environmentally friendly agents.

[0038] The present invention does not require crushing and grinding. By means of the self-grinding and scrubbing through the collision between the raw ore particles of cryptocrystalline silica, and through the processes of dispersion agent-assisted cleavage, dispersion, desliming - magnetic separation - screening - flotation - pickling - calcination - water quenching - pickling, the high-purity quartz concentrate obtained has a SiO₂ content of 99.9907%. The by-products such as the middlings in flotation, +40 mesh coarse particles, magnetic substances, and fine mud can be used as building materials, aerated bricks, cement ingredients, etc. The present invention realizes the high-value cascade utilization of Cambrian cryptocrystalline silica resources, improves the current situation of using high-quality resources in a poor way, increases the economic benefits of the mine, conforms to the concept of green mines, and has strong applicability and a wide application range. It can also provide an economical and efficient purification method for the high-value utilization of other types of cryptocrystalline silica.

[0039] The following further describes in detail the specific embodiments of the present invention with reference to the accompanying drawings. Description of the Drawings

[0040] Figure 1 It is a schematic flow diagram of the method of the present invention.

[0041] Figure 2 It is the XRD spectra of the raw cryptocrystalline silica ore and the ore mud. Specific Embodiments

[0042] Example 1

[0043] 150 kg of representative cryptocrystalline silica samples were collected from a Cambrian cryptocrystalline silica mine in Guizhou. The samples were air-dried in the sun. The appearance was loose and showed an iron-impregnated red color. Without crushing treatment, after gently hitting and rolling with a wooden mallet, it was screened with a 1 mm sieve. The materials on the sieve such as grass roots and lumpy stones were discarded, and the uniform powder below -1 mm was used as the test raw ore. The multi-element analysis results of the raw ore are shown in Table 1, the XRD analysis results of the raw ore are shown in Table 2, the XRD analysis results of the 400-mesh fine mud are shown in Table 3, and the XRD spectra of the raw ore and the 400-mesh fine mud are shown in Figure 2 .

[0044] Table 1 Analysis Results of the Raw Ore (%) Element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO Content 92.39 3.41 1.66 0.021 Element <![CDATA[K2O]]> <![CDATA[Na2O]]> <![CDATA[TiO2]]> MgO Content 0.16 0.016 0.091 0.069

[0045] Table 1 shows that the SiO₂ content of the cryptocrystalline silica raw ore is 92.39%, the Al₂O₃ content is 3.41%, and the Fe₂O₃ content is 1.66%. It shows that the higher contents of clay minerals, iron, etc. in the Cambrian cryptocrystalline silica raw ore in Guizhou affect the quality of the ore and cause great difficulty in purification.

[0046] Table 2 XRD Analysis Results of the Raw Ore (%) Mineral Name Quartz Kaolinite Feldspar Hematite Content 91.52 5.71 2.75 0.03

[0047] Table 2 shows that the quartz mineral content in the cryptocrystalline silica raw ore is 91.52%, the kaolinite mineral content is 5.71%, the feldspar mineral content is 2.75%, and there is a small amount of hematite, indicating that the aluminum-containing minerals are mainly kaolinite and feldspar.

[0048] Table 3 XRD Analysis Results of 400-Mesh Fine Slime (%) Mineral Name Quartz Kaolinite Feldspar Hematite Content 73.20 23.47 3.14 0.19

[0049] For the fine slime removed by scrubbing the original ore in Table 3, the content of quartz minerals is 73.20%, the content of kaolinite minerals is 23.47%, the content of feldspar minerals is 3.14%, and the content of hematite is 0.19%. This shows that scrubbing removes the symbiotic silicate clay impurities and the disseminated impurities on the surface and in the cracks of quartz particles, thereby improving the quality of quartz concentrate and playing an important role in the subsequent purification to prepare 4N-grade high-purity quartz.

[0050] Combined with the Figure 1 process flow shown, weigh 400 grams of the mixed Cambrian powder quartz original ore and pour it into the scrubbing machine. For the XRD spectra of the powder quartz original ore and ore slime, see Figure 2 , add 400 ml of water, and scrub for 30 minutes. One method is to use the collision and self-grinding scrubbing between powder quartz particles, and the other is to screen out the +40-mesh coarse particles, add zirconium balls for scrubbing in equal proportion, and conduct siphon sedimentation de-sludging tests respectively. De-sludge once every 5 minutes, and draw 14 times until the scale line reaches 1000. The results of the de-sludging scheme are shown in Table 4.

[0051] Table 4 De-sludging of the Original Ore by Self-Grinding Scrubbing and Scrubbing with Added Zirconium Balls (%) Scrubbing and desliming scheme Product Yield Grade Recovery rate <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> Particle autogenous grinding and scrubbing Slime 30.77 76.66 11.88 5.14 25.64 91.87 90.69 Quartz sand 69.23 98.80 0.41 0.21 74.36 8.82 9.31 Zirconium ball scrubbing Slime 30.00 77.94 10.81 4.68 25.38 91.18 90.30 Quartz sand 70.00 98.24 0.51 0.25 74.62 8.13 9.70

[0052] Using the collision and self-grinding scrubbing and dispersion de-sludging between powder quartz particles, the quality of the obtained quartz sand is better than that obtained by scrubbing with added zirconium balls, and the removed slime contains more aluminum and iron, with a high impurity removal rate. Adding zirconium balls will increase the two screening processes. Therefore, using the collision and self-grinding scrubbing between quartz particles can save costs and improve de-sludging efficiency.

[0053] Weigh 400 grams of the mixed Cambrian powder quartz original ore and pour it into the scrubbing machine, add 400 ml of water, add a dispersant for coupled scrubbing, scrub for 30 minutes, pour it into a 2000-ml graduated cylinder for sedimentation de-sludging, de-sludge once every 5 minutes, and draw 10 times until the scale line reaches 800. Analyze the silicon, aluminum, and iron in the slime and sand to examine the de-sludging effects under different conditions. The results are shown in Table 5.

[0054] Table 5 De-sludging Results of Scrubbing (%) Dispersant Product Yield Grade Recovery rate <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> Dispersant 0 Slime 30.77 76.66 11.88 5.14 25.64 91.18 90.30 Quartz sand 69.23 98.80 0.51 0.25 74.36 8.82 9.70 Phosphate 300g / t Slime 29.25 76.53 12.02 5.30 24.30 92.79 92.18 Quartz sand 70.75 98.56 0.39 0.19 75.70 7.21 7.82 Phosphate 600g / t Slime 30.00 76.62 11.41 5.23 24.92 94.75 94.35 Quartz sand 70.00 98.90 0.27 0.13 75.08 5.25 5.65 Phosphate 800g / t Slime 26.33 72.34 14.13 6.16 20.61 95.28 95.86 Quartz sand 73.67 99.58 0.25 0.095 79.39 4.72 4.14 Phosphate 1000g / t Slime 26.12 72.00 13.82 6.21 20.44 95.69 94.01 Quartz sand 73.88 99.10 0.22 0.14 79.56 4.31 5.99 Inorganic strong base 600g / t Slime 33.05 78.64 11.27 4.74 28.17 96.45 94.34 Quartz sand 66.95 99.01 0.20 0.14 71.83 3.55 5.66 Recycling of dispersant backwater Slime 31.61 77.80 11.18 5.14 26.70 94.86 94.06 Quartz sand 68.39 98.70 0.28 0.15 73.30 5.14 5.94

[0055] The dispersant phosphate at 800 g / t has the best coupling scrubbing and de-sludging effect, with a sludge removal rate of 26.33%, aluminum and iron removal rates both greater than 95%, a quartz sand ore yield of 73.67%, the SiO2 grade of quartz sand increased from 92.39% of the original ore to 99.58%, Al2O3 decreased from 3.41% of the original ore to 0.25%, and Fe2O3 decreased from 1.66% of the original ore to 0.095%, significantly improving the quality of the silica sand.

[0056] Add the coarse quartz sand obtained after de-sludging to a wet high-intensity magnetic separator. The magnetic separation operation is a single-stage high-intensity magnetic separation with a magnetic field intensity of 1.4 - 2.0 T to obtain non-magnetic substances and magnetic substances.

[0057] Screen out the +40-mesh coarse particles from the non-magnetic substances. This part of the product does not meet the particle size requirements of high-purity quartz and has high iron, aluminum, and other impurities. The purpose is to improve the quality of the quartz entering the flotation process.

[0058] Weigh a certain amount of non-magnetic substances (-40 + 400 mesh) and add them to a 0.5 L flotation cell of an XFD12 flotation machine to conduct reverse flotation of feldspar and other impurity minerals. The flotation pulp concentration is 10 - 30%, adjust the pulp pH to 2 - 3, stir for 1 minute, add 300 g / t of collector. The flotation collector is a mixture of compound amine, fatty acid, and silicate inhibitor, and the weight percentage of compound amine, fatty acid, and silicate inhibitor is 7:7:1; the stirring rate is 1200 r / min, stir for 1 minute, and the flotation time is 2 minutes. The foam product is feldspar and impurity minerals, and the product in the cell is the flotation quartz concentrate. To ensure the grade of the flotation quartz concentrate, conduct multiple scavenging operations according to this procedure, and mix the flotation products as the final flotation middlings.

[0059] Screen out the -40 + 80-mesh coarse particles from the flotation quartz concentrate, weigh 20 grams of the sample and put it into a high-pressure reactor for heating acid leaching test. The mixed acid used is HCl:HNO3:HF = (2 - 4):1:1, the liquid-solid ratio is 1:2, the leaching temperature is 80 °C, and the leaching time is 24 hours. After the acid leaching, wash it with ultrapure water until neutral, and then use ultrasonic washing for 10 minutes to further remove the impurities on the surface of the quartz particles, and dry it to obtain the acid-leached concentrate.

[0060] Calcine the acid-leached concentrate in a muffle furnace at 1050 °C for 1 hour, pour it into ultrapure water for water quenching. High-temperature calcination causes the volume of quartz to expand and deform. During the quenching process, the fluid inclusions and mineral inclusions impurities inside the quartz are exposed from the inside to the outside, and lattice impurity elements such as Al, K, and Na are enriched on the surface of the quartz, which is beneficial for deep impurity removal in the subsequent acid washing process.

[0061] The calcined and water-quenched samples were dried and placed in a high-pressure reactor for secondary heating and acid leaching. The mixed acid used was HCl:HNO3:HF = (2 - 4):1:1, the liquid-solid ratio was 1:2, the leaching temperature was 80 °C, and the leaching time was 24 hours. It was washed with ultrapure water until neutral, and then ultrasonically washed for 10 minutes to remove the impurities on the surface of the quartz particles. After drying, 15 impurities were measured by ICP-OES. After subtraction, the SiO2 content of the high-purity quartz concentrate was 99.9908%.

[0062] 15 g of -80 + 400 mesh fine particles screened from the flotation quartz concentrate were poured into a high-pressure reactor for direct primary acid washing. The mixed acid used was HCl:HNO3:HF = (2 - 4):1:1, the liquid-solid ratio was 1:2, the leaching temperature was 80 °C, and the leaching time was 24 hours. It was ultrasonically washed for 10 minutes to remove the impurities on the surface of the quartz particles. After drying, 15 impurities were measured by ICP-OES to obtain a 3N7 grade high-purity quartz concentrate. The second scheme was the same acid washing - calcination - acid washing purification process as that of the -40 + 80 mesh coarse particles. The analysis results of the coarse particles, fine particles, and by-products are shown in Tables 6, 7, 8, and 9.

[0063] Table 6 Analysis results of -40 + 80 mesh coarse particles by acid washing - calcination - acid washing Element <![CDATA[SiO2 / %]]> Al Ba Ca Co Cr Cu Fe Content μg / g 99.9908 51.38 0.76 11.73 <0.01 <0.01 0.1 1.34 Element K Li Mg Mn Na Ni Ti Zr Content μg / g 10.91 1.63 2.73 0.01 10.80 <0.01 0.1 0.08

[0064] Table 7 Analysis results of -80 + 400 mesh fine particles by primary acid washing Element <![CDATA[SiO2 / %]]> Al Ba Ca Co Cr Cu Fe Content μg / g 99.9726 61.29 0.87 158.96 <0.01 <0.01 0.12 2.34 Element K Li Mg Mn Na Ni Ti Zr Content μg / g 12.8 2.23 24.46 0.04 11.05 <0.01 0.21 0.08

[0065] Table 8 Analysis results of -80 + 400 mesh fine particles by acid washing - calcination - acid washing Element <![CDATA[SiO2 / %]]> Al Ba Ca Co Cr Cu Fe Content μg / g 99.9869 54.74 0.62 45.01 <0.01 <0.01 0.14 1.87 Element K Li Mg Mn Na Ni Ti Zr Content μg / g 11.63 1.97 3.27 0.01 11.34 <0.01 0.31 0.09

[0066] In the experiment of Example 1, for the -40 + 80 mesh coarse particles in Table 6, after the acid washing - calcination - acid washing purification process, the SiO2 purity reached 99.9908%, which was greater than 4N. For the -80 + 400 mesh fine particles, after primary acid washing, the SiO2 purity was 99.9726%, and after acid washing - calcination - acid washing, the SiO2 purity reached 99.9869%.

[0067] Table 9 Analysis results of by-products (%) Product Yield <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> Ore slime 26~32 77.01 11.37 5.23 Magnetic substance 1.6~2 95.92 1.21 0.65 +40 mesh coarse particles 3~4 98.78 0.43 0.17 Floatation middlings 12~14 97.92 0.45 0.28

[0068] The by-products such as slime, magnetic substances, +40 mesh coarse particles, and middlings in flotation contain relatively high silicon and can be used as cement ingredients, aerated bricks, or new building materials.

[0069] Example 2

[0070] The raw silica sand is directly stirred and scrubbed without a dispersant for 30 minutes, and the 400-mesh fine mud is settled and removed. The coarse sand is subjected to magnetic separation - flotation. The flotation quartz concentrate is screened to obtain coarse particles of -40 + 80 mesh and -80 + 200 mesh. 15 grams of samples are respectively weighed and subjected to high-temperature calcination in a muffle furnace at a calcination temperature of 900 °C for 1 hour, quenched with water, dried, pickled, then calcined for the second time at 1050 °C for 1 hour, quenched with water, dried, and pickled for the second time (the pickling ratio, liquid-solid ratio, etc. are the same as in the example). Ultrasonic cleaning is used to further remove impurities on the surface of the quartz particles, dried, and 15 impurities are measured by ICP-OES. The analysis results of the prepared high-purity quartz concentrate are shown in Table 10 and Table 11.

[0071] Table 10 Analysis Results of Coarse Particles of -40 + 80 Mesh after Two Calcinations - Two Picklings Element <![CDATA[SiO2 / %]]> Al Ba Ca Co Cr Cu Fe Content μg / g 99.9905 50.62 1.08 13.48 0.01 0.01 0.3 2.1 Element K Li Mg Mn Na Ni Ti Zr Content μg / g 10.68 1.83 1.98 0.07 12.48 0.01 0.05 0.05

[0072] Table 11 Analysis Results of Coarse Particles of -80 + 200 Mesh after Two Calcinations - Two Picklings Element <![CDATA[SiO2 / %]]> Al Ba Ca Co Cr Cu Fe Content μg / g 99.9893 53.84 1.0 21.19 0.01 0.01 0.4 2.65 Element K Li Mg Mn Na Ni Ti Zr Content μg / g 11.09 2.16 2.67 0.07 12.09 0.02 0.07 0.06

[0073] In the experiment of Example 2, the results in Table 10 and Table 11 show that after two calcinations and two picklings for purification, the SiO2 purity of the coarse particles of -40 + 80 mesh can reach 99.9905%, while for the fine particles of -80 + 200 mesh after two calcinations and two picklings for purification, the SiO2 purity is 99.9893%, which cannot reach 4N.

[0074] Example 3

[0075] Weigh 400 g of raw silica sand, add 600 g / t of dispersant phosphate, add 400 ml of water, stir and scrub for 30 minutes to remove the 400-mesh fine mud. The coarse sand is subjected to magnetic separation - flotation. The flotation quartz concentrate is screened to obtain coarse particles of -40 + 80 mesh and -80 + 400 mesh. 50 grams of samples are respectively weighed and subjected to high-temperature calcination in a muffle furnace at a calcination temperature of 900 °C for 1 hour, quenched with water, dried, pickled, then calcined for the second time at 1050 °C for 1 hour, quenched with water, dried, and pickled for the second time (the pickling ratio, liquid-solid ratio, etc. are the same as in the example). Ultrasonic cleaning is used to further remove impurities on the surface of the quartz particles, dried, and 15 impurities are measured by ICP-OES. The analysis results of the prepared high-purity quartz concentrate are shown in Table 12 and Table 13.

[0076] Table 12 Analysis Results of Coarse Particles of -40 + 80 Mesh after Two Calcinations - Two Picklings Element <![CDATA[SiO2 / %]]> Al Ba Ca Co Cr Cu Fe Content μg / g 99.9904 49.96 1.27 14.11 <0.01 <0.01 0.3 2.33 Element K Li Mg Mn Na Ni Ti Zr Content μg / g 10.78 1.78 2.14 0.08 11.86 0.01 0.42 0.10

[0077] Table 13 Analysis Results of Coarse Particles of -80 + 400 Mesh after Two Calcinations - Two Picklings Element <![CDATA[SiO2 / %]]> Al Ba Ca Co Cr Cu Fe Content μg / g 99.9887 56.47 1.15 21.3 0.01 0.04 0.41 3.7 Element K Li Mg Mn Na Ni Ti Zr Content μg / g 11.67 2.17 3.27 0.14 12.29 0.01 0.61 0.13

[0078] The test of Example 3, the results in Table 12 and Table 13 show that after the coarse particles of -40+80 mesh are calcined twice and pickled twice for purification, the purity of SiO2 can reach 99.9904%, while the fine particles of -80+400 mesh are calcined twice and pickled twice for purification, and the purity of SiO2 is 99.9887%, which cannot reach 4N.

[0079] Example 4

[0080] Weigh 400 g of the original powder quartz ore, add 600 g / t of dispersant phosphate, add 400 ml of water, stir and scrub for 30 minutes, settle and remove the 400-mesh fine mud to obtain coarse sand. The coarse sand is subjected to magnetic separation with a magnetic field strength of 2.0 T to remove magnetic substances. After the non-magnetic substances are screened to remove the +40-mesh coarse particles, they enter flotation to obtain flotation concentrate. The flotation concentrate of -40+400 mesh is directly subjected to pickling-calcination-pickling purification without classification. The pickling ratio, liquid-solid ratio, calcination temperature, etc. are the same as those in Example 1. Finally, the quartz particles on the surface of the concentrate are further removed by ultrasonic cleaning, dried, and 15 impurities are measured by ICP-OES. The analysis results of the prepared high-purity quartz concentrate are shown in Table 14.

[0081] Table 14 - Analysis results of pickling-calcination-pickling of -40+400 mesh Element <![CDATA[SiO2 / %]]> Al Ba Ca Co Cr Cu Fe Content μg / g 99.9888 55.24 0.75 22.98 <0.01 <0.01 0.13 2.42 Element K Li Mg Mn Na Ni Ti Zr Content μg / g 11.24 1.94 4.4 0.04 11.37 0.01 1.43 0.12

[0082] The test of Example 4, the results in Table 14 show that the flotation concentrate of -40+400 mesh is directly subjected to pickling-calcination-pickling purification without classification, and the purity of SiO2 reaches 99.9888, which cannot reach 4N.

[0083] Example 5

[0084] Weigh 400 g of the original powder quartz ore, add 500 g / t of dispersant phosphate + 500 g / t of inorganic strong base for synergistic scrubbing and de-sludging, with a pulp concentration of 50% and a scrubbing time of 30 minutes. The coarse sand is subjected to magnetic separation and flotation. The flotation concentrate is screened into -40+80 mesh and -40+100 mesh and subjected to pickling-calcination-pickling purification respectively. The results are shown in Table 15 and Table 16.

[0085] Table 15 - Analysis results of pickling-calcination-pickling of -40+80 mesh Element <![CDATA[SiO2 / %]]> Al Ba Ca Co Cr Cu Fe Content μg / g 99.9913 48.18 0.70 10.96 <0.01 <0.01 0.1 1.34 Element K Li Mg Mn Na Ni Ti Zr Content μg / g 10.71 1.61 2.45 0.01 10.58 0.06 0.06 0.04

[0086] Table 16 - Analysis results of pickling-calcination-pickling of -40+100 mesh Element <![CDATA[SiO2 / %]]> Al Ba Ca Co Cr Cu Fe Content μg / g 99.9907 49.43 0.7 11.59 <0.01 <0.01 0.11 1.44 Element K Li Mg Mn Na Ni Ti Zr Content μg / g 10.79 1.73 2.69 0.01 10.24 <0.01 0.10 0.10

[0087] Example 5 test, the analysis results in Table 15 and Table 16 show that for the flotation concentrate classification of -40 + 80 mesh and -40 + 100 mesh, after pickling - calcination - pickling purification, high - purity quartz concentrate with SiO2 content above 4N can be obtained. The comparison results between Table 6 and Table 15 show that the synergistic effect of dispersants of phosphate type and inorganic strong base type for slime removal is better than single use, and the good slime removal effect in the early stage plays a key role in the subsequent purification.

[0088] The above examples show that classifying the flotation quartz concentrate into -40 + 80 mesh and -40 + 100 mesh for pickling - calcination - pickling or two - stage calcination and two - stage pickling can obtain 4N - grade high - purity quartz concentrate. However, for the fine particles of -80 + 400 mesh or unclassified -40 + 400 mesh, whether using pickling - calcination - pickling or two - stage calcination and two - stage pickling, they cannot reach the 4N grade. This shows that the finer the particle size of the powder quartz, the higher the impurity content. The fine particles contain high levels of fluid inclusions and lattice impurities. Calcination can better remove Ca 2+ and Mg 2+ .

[0089] In summary, in order to save the purification cost and obtain a higher - yield 4N - grade high - purity quartz concentrate (the yield of -40 + 80 mesh in the flotation concentrate accounts for about 26% of the flotation concentrate yield and about 15% of the original ore yield; the yield of -40 + 100 mesh in the flotation concentrate accounts for 41% of the flotation concentrate yield and about 25% of the original ore yield), the best purification process for this Cambrian powder quartz is dispersant - assisted stirring scrubbing for slime removal - magnetic separation - screening - flotation - classifying to obtain -40 + 100 mesh coarse sand, and then preparing 4N - grade high - purity quartz concentrate through pickling - calcination - pickling purification process. The -100 + 400 mesh fine particles are pickled once to obtain 3N7 - grade secondary quartz concentrate, realizing the hierarchical comprehensive utilization of this Cambrian powder quartz resource and improving the economic value of this ore. High - purity quartz concentrate with different particle sizes and purities can be prepared according to the downstream market demand.

Claims

1. A method for purifying Cambrian powder quartz to prepare 4N high-purity quartz, characterized in that, It includes the following steps: Step 1, coupled scrubbing of raw ore with dispersant: Using Cambrian pulverized quartz as the selected raw ore, adding a dispersant and water, and scrubbing and stirring in a scrubber to obtain a scrubbed pulp; Step 2, sedimentation and de-sludging: Pour the scrubbed pulp obtained in Step 1 into a graduated cylinder, fully stir and perform gravitational sedimentation to remove the sludge. Repeat this process multiple times for de-sludging until the supernatant is clear, obtaining quartz coarse sand and sludge; Step 3, high-intensity magnetic separation: Perform high-intensity magnetic separation on the quartz coarse sand material obtained in Step 2 to obtain magnetic substances and non-magnetic substances; Step 4, screening: Screen out the +40 mesh coarse particles from the non-magnetic substances obtained in Step 3 to increase the silicon content in the -40 + 400 mesh particle size; Step 5, reverse flotation: Pour the -40 + 400 mesh non-magnetic substances obtained in Step 4 into a flotation machine, adjust the pulp pH, add a collector, and perform reverse flotation multiple times to obtain flotation concentrate and middlings; among them, the flotation collector is a mixture of compound amine, fatty acid, and silicate inhibitor; the weight percentage of compound amine, fatty acid, and silicate inhibitor is 7:7:1; Step 6, acid washing: Screen out the -40 + 80 mesh coarse particles from the flotation concentrate obtained in Step 5 for acid washing and ultrasonic cleaning to obtain acid-leached concentrate; Step 7, calcination - water quenching - acid washing: Calcinate - water quench - acid wash the acid-leached concentrate obtained in Step 6 to obtain 4N grade high-purity quartz concentrate; Step 8, acid washing: Screen out the -80 + 400 mesh fine particles from the flotation quartz concentrate obtained in Step 5 for one-time acid washing to prepare 3N7 grade sub-high-purity quartz concentrate; Among them, the sludge obtained in Step 2, the magnetic substances obtained in Step 3, the +40 mesh coarse particles obtained in Step 4, and the middlings in Step 5 flotation can be used to make aerated bricks and new building materials.

2. The method for purifying Cambrian silt quartz to prepare 4N high-purity quartz according to claim 1, wherein: The Cambrian pulverized quartz is a weathered siliceous raw material that does not require crushing and grinding.

3. A method for purifying Cambrian powder quartz to prepare 4N high-purity quartz according to claim 1, characterized in that: In Step 1, the dispersant is one or a mixture of two of inorganic strong bases and phosphates, and the dosage of the dispersant is 300 - 1000 g / t.

4. A method for purifying Cambrian powder quartz to prepare 4N high-purity quartz according to claim 1, characterized in that: In Step 2, the sludge is extracted once every 5 minutes by gravitational sedimentation, and the extraction times are 10 - 14 times to remove the fine sludge below 400 mesh.

5. A method for purifying Cambrian powder quartz to prepare 4N grade high-purity quartz according to claim 1, characterized in that: In Step 3, the high-intensity magnetic separation is wet magnetic separation, the magnetic separation operation is single-stage magnetic separation, and the magnetic field intensity is 1.4 - 2.0 T.

6. The method for purifying Cambrian powder quartz to prepare 4N grade high-purity quartz according to claim 1, characterized in that: In Step 5, the reverse flotation is pneumatic flotation, and the process conditions are: pulp concentration is 10 - 30%, pulp pH is 2 - 3, the acid for adjusting the pulp is one or a mixture of sulfuric acid and hydrofluoric acid, the dosage of the collector is 300 - 600 g / t, the stirring rate is 1200 - 1500 r / min, the flotation time is 1 - 2 min, and perform multiple flotation until all impurities are selected out.

7. A method for purifying Cambrian ground quartz to prepare 4N high-purity quartz according to claim 1, characterized in that, In Step 6, the acid washing uses a mixed acid, and the mixed acid is a mixture of nitric acid, hydrochloric acid, and hydrofluoric acid, and the leaching time is 4 - 24 hours.

8. A method for purifying Cambrian powder quartz to prepare 4N grade high-purity quartz according to claim 1, characterized in that: In Step 7, the calcination conditions are: raise the temperature of the muffle furnace to 1050 °C and calcinate for 1 hour, the acid washing uses a mixed acid, and the mixed acid is a mixture of nitric acid, hydrochloric acid, and hydrofluoric acid, and the leaching time is 4 - 24 hours.

9. A method for purifying Cambrian ground quartz to prepare 4N high-purity quartz according to claim 1, characterized in that: In Step 8, the acid washing leaching time is 4 - 24 hours.

10. A method for purifying Cambrian ground quartz to prepare 4N high-purity quartz according to claim 1, characterized in that: The waste acid after acid washing in Step 8 is recycled and used as the acid for acid washing in Step 6.

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