Method for preparing high-purity quartz by effectively removing aluminum and titanium components in quartz ore

Abstract

The invention provides a method for preparing high-purity quartz by effectively removing aluminum and titanium components in quartz ore, which comprises the following steps: pretreating the quartz ore to obtain first quartz particles; carrying out ammonium salt flotation, washing and drying on the first quartz particles to obtain second quartz particles; and carrying out segmented roasting, acid pickling, water washing and drying on the second quartz particles to obtain the high-purity quartz. The invention provides a mode of mixing and roasting a compound additive, namely ammonium chloride and ammonium sulfate, together with quartz sand, so that the synergistic effect of the compound additive on quartz ore particles during roasting is fully utilized, and inclusion impurities and lattice impurities which are wrapped in quartz and are difficult to expose are activated and removed; the mass percentage content of SiO2 in the prepared high-purity quartz can be increased from 99.9% to 99.999%.

Description

Technical Field

[0001] This invention relates to the field of high-purity material preparation, and more specifically, to a method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz. Background Technology

[0002] High-purity quartz is a high-purity material with a SiO2 mass percentage greater than 99.99%. It is a mineral product obtained by refining ores such as crystal, vein quartz, and granite pegmatite. It is the material basis for high-end products in the silicon industry and has excellent physical and chemical properties such as high temperature resistance, corrosion resistance, low thermal expansion, high insulation and high light transmittance. It is widely used in semiconductors, photovoltaics, optical fiber communication, optics, electric light sources and other fields. It is a key basic material for strategic emerging industries such as next-generation information technology, new energy and high-end equipment.

[0003] Al and Ti are impurity elements that severely affect the quality of quartz. They are difficult to completely remove from quartz, and the types of impurity minerals they present in include ilmenite, hematite, magnetite, hematite, tourmaline group, and kyanite group. These minerals often contain isomorphous substitutions of Ti, Al, Mn, Fe, Ca, and Mg; and often contain micro-inclusions of rutile and ilmenite, as well as lattice impurities. However, existing magnetic separation technologies and their combined processes have significant defects and shortcomings in the deep removal of Al and Ti impurities, severely restricting the final grade and preparation efficiency of high-purity quartz products, including the following aspects: 1. Ineffective removal of non-magnetic / weakly magnetic minerals: A large number of Al-containing minerals (such as kyanite, feldspar, and some mica) and Ti-containing minerals (such as rutile) are inherently very weakly magnetic, and strong magnetic separation is inefficient in separating them, resulting in a large amount of these impurities remaining.

[0004] 2. Ineffective against lattice impurities and micro-inclusions: Magnetic separation, as a physical separation method, is fundamentally incapable of dealing with Al that exists in the quartz lattice in an isomorphic form. 3+ Ti 4+ Ions are also helpless against tightly encapsulated, fine mineral inclusions because they cannot be exposed and separated.

[0005] 3. Limitations as a pretreatment method: Although magnetic separation can initially reduce the content of some impurities, the purity of the output is far from meeting the standard of high-purity quartz (4N and above). If conventional flotation or acid leaching is relied upon in the subsequent process, due to its lack of specificity, it not only consumes a large amount of reagents and is costly, but also fails to remove stubborn lattice impurities and inclusions effectively, making it difficult to achieve a breakthrough in "high purification" of quartz quality.

[0006] Therefore, the industry urgently needs to develop a more targeted and efficient deep purification method that can effectively overcome the challenges of removing lattice impurities and micro-inclusions, in order to make up for the shortcomings of existing magnetic separation processes and provide a reliable technical solution for the preparation of ultra-high purity quartz sand. Summary of the Invention

[0007] The purpose of this invention is to overcome at least one of the aforementioned deficiencies in the prior art. For example, one objective of this invention is to provide a method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz; another objective of this invention is to provide a high-purity quartz.

[0008] To achieve the above objectives, the present invention provides a method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz, the method comprising the following steps: 1) Pre-treat the quartz ore to obtain the first quartz particles; 2) The first quartz particles are subjected to ammonium salt flotation, water washing and drying to obtain the second quartz particles; 3) The second quartz particles are subjected to staged roasting, acid washing, water washing and drying to obtain high-purity quartz.

[0009] Optionally, the quartz ore includes at least one of natural crystal, granite pegmatite, vein quartz, and quartzite; the quartz ore contains mineral impurities of aluminum and titanium, micro-inclusions, and lattice impurities; the mineral impurities include two or more of feldspar, mica, ilmenite, hematite, magnetite, hematite, tourmaline group, and kyanite group; the micro-inclusions and lattice impurities are present inside the quartz ore; the pretreatment includes crushing-screening, scrubbing and desliming, strong magnetic separation, acid reverse flotation, and water washing.

[0010] Optionally, the particle size of the product obtained after crushing and screening is -50 to +120 mesh; the solid-liquid mass-volume ratio of quartz ore to scrubbing liquid in the scrubbing and desliming process is 1:3 to 1:8 kg / L; the scrubbing and desliming time is 10 min to 60 min; and the scrubbing and desliming is carried out by one or both of mechanical scrubbing and ultrasonic scrubbing; the strong magnetic separation is carried out by a superconducting magnetic separator, a high-gradient vertical ring magnetic separator, or a wet strong magnetic separator; the magnetic field strength of the strong magnetic separation is 1.0 to 4.0 T; the magnetic separation cycle is 2 to 5 times; and the magnetic separation endpoint is when the proportion of magnetic product is less than 0.1% of the feed mass.

[0011] Optionally, the collector used in the acid reverse flotation includes dodecylamine, with a dosage of 100-200 g / t. When performing the acid reverse flotation, dilute sulfuric acid or hydrofluoric acid is used to adjust the pH of the quartz ore pulp to 1.5-3, and the mass fraction of the pulp concentration is 10%-30%. The water washing is the washing of the concentrate after the acid reverse flotation with deionized water, and the washing endpoint is when the pH of the washing solution is greater than 6.5.

[0012] Optionally, the reagents used in the ammonium salt flotation in step 2) include ammonium salt and collector; the ammonium salt includes one or both of ammonium sulfate and ammonium chloride, and the mass ratio of the ammonium salt to the first quartz particles is 1:3 to 1:50; the collector and its concentration in the flotation solution are 5-60 mg / L of ferrous chloride or ferric chloride, 1-10 mg / L of citric acid or ascorbic acid, and 80-300 mg / L of sodium oleate; the mass fraction of the slurry for ammonium salt flotation is 10% to 35%; the washing is the washing of the concentrate after ammonium salt flotation with deionized water, and the washing endpoint is when the pH of the washing solution is greater than 6.5; the drying is the process of dehydrating the washed product using one of the following methods: electric heating blasting, vacuum drying, and freeze drying, until the water content is less than 0.1%, to obtain the second quartz particles.

[0013] Optionally, the segmented calcination in step 3) refers to mixing the second quartz particles with the additives and then performing segmented calcination in a calcination furnace; the segmented calcination refers to the heating process being divided into two stages, wherein the calcination temperature of the first stage is raised from room temperature to 600℃ and held for 30~240min, and the calcination temperature of the second stage is raised from 600℃ to 1200℃ and held for 30~240min.

[0014] Optionally, the mixing is carried out using one of a mixer, an air jet mixer, and a dynamic reaction vessel, with a mixing time of 3 to 60 minutes; the additives include ammonium sulfate and ammonium chloride, wherein the mass ratio of ammonium sulfate to the second quartz particles is 1:10 to 1:50, and the mass ratio of ammonium chloride to the second quartz particles is 1:20 to 1:50; the calcining furnace includes at least one of an atmosphere sintering furnace, a tube furnace, a rotary kiln, and a suspension furnace, and the calcining atmosphere in the calcining furnace is an inert gas, including one or two of nitrogen, helium, and argon.

[0015] Alternatively, the pickling in step 3) is to use a mixed acid solution to pickle the roasted product after segmented roasting, with the pickling temperature being 80~220℃ and the pickling time being 180~720min. The mixed acid solution comprises hydrofluoric acid, hydrochloric acid, nitric acid, and sulfuric acid, wherein the concentration of hydrofluoric acid is 0.2~2.0 mol / L, the concentration of hydrochloric acid is 1.2~3.2 mol / L, the concentration of nitric acid is 1.6~4.8 mol / L, and the concentration of sulfuric acid is 0.5~2.0 mol / L; the solid-liquid ratio of the calcined product to the mixed acid solution is 1:2~1:5 kg / L.

[0016] Optionally, the water washing in step 3) refers to the product after acid washing using deionized water, and the endpoint of the washing is when the pH of the washing solution is greater than 6.5; the drying refers to the process of dehydrating the product after water washing using one of the following methods: electric heating blasting, vacuum drying, and freeze drying, until the water content is less than 0.1%, to obtain high-purity quartz.

[0017] In another aspect, the present invention provides a high-purity quartz, which can be prepared by the above-described preparation method.

[0018] Optionally, the SiO2 content in the high-purity quartz is 99.99%~99.999%; the content of aluminum and titanium impurities is less than 15μg / g, which meets the standard for photovoltaic-grade high-purity quartz sand.

[0019] Compared with the prior art, the beneficial effects of the present invention include at least one of the following: (1) The present invention has a significant effect on removing mineral impurities such as ilmenite, hematite, magnetite, hematite, tourmaline group, kyanite group and mica group during the purification of quartz, as well as reducing the Al and Ti impurity components in the quartz lattice; the method of the present invention can reduce the Al content in the final high-purity quartz product after purifying quartz ore with Al content of 104 μg / g and Ti content of 77 μg / g to 8 μg / g and Ti content to 11 μg / g.

[0020] (2) The present invention provides a method of mixing and roasting quartz sand with a composite additive, namely ammonium chloride and ammonium sulfate. This fully utilizes the synergistic effect of the composite additive on quartz particles during roasting, and activates and removes inclusion impurities and lattice impurities that are difficult to expose inside the quartz. In other words, the chlorination roasting process is enhanced by using sulfuric acid, which can remove Al and Ti impurity components in quartz particles in a targeted and efficient manner.

[0021] (3) The mass percentage of SiO2 in the high-purity quartz prepared by the method of the present invention can be increased from 99.9% to 99.999%, and the contents of various impurity elements, mainly Al and Ti, are significantly reduced. Attached Figure Description

[0022] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which: Figure 1 A schematic diagram of a process flow for preparing high-purity quartz by effectively removing aluminum and titanium components from quartz ore according to the present invention is shown.

[0023] Figure 2 A photograph of the appearance of sample Q-1 used in Examples 1-3 of the present invention is shown.

[0024] Figure 3 The XRD analysis diagram of sample Q-1 used in Examples 1-3 of this invention is shown.

[0025] Figure 4 A comparison diagram of tailings and concentrate from ammonium salt flotation in Example 3 of the present invention is shown.

[0026] Figure 5 A photograph of the high-purity quartz prepared in Example 3 of the present invention is shown. Detailed Implementation

[0027] In the following, a method for preparing high-purity quartz by effectively removing aluminum and titanium components from quartz ore will be described in detail with reference to exemplary embodiments.

[0028] It should be noted that "first," "second," etc., are used only for the convenience of description and distinction, and should not be interpreted as indicating or implying relative importance.

[0029] This invention is highly effective in removing impurity minerals such as hematite, magnetite, hematite, tourmaline group, and kyanite group during the purification of quartz, and in reducing the proportion of micro-inclusions and lattice impurities containing Al and Ti impurity elements inside the quartz. It can promote the further development of high-purity quartz production technology in China.

[0030] Exemplary Example 1 This exemplary embodiment provides a method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz. Figure 1 The diagram shown is a schematic flow chart of the method for preparing high-purity quartz according to the present invention. Figure 1 As shown, the preparation process can be summarized as follows: crushing and screening the raw ore, scrubbing and desliming, strong magnetic separation, acid reverse flotation, followed by washing and drying to obtain first quartz particles; ammonium salt flotation, washing, and drying of the first quartz particles to obtain second quartz particles; and staged roasting, acid washing, washing, and drying of the second quartz particles to obtain high-purity quartz. The screening tailings and flotation tailings are collected for other uses.

[0031] Specifically, the method may include the following steps: S1. Pre-treat the quartz ore to obtain the first quartz particles.

[0032] In this embodiment, the quartz ore includes at least one of natural crystal, granite pegmatite, vein quartz, and quartzite; the quartz ore contains mineral impurities of aluminum and titanium, micro-inclusions, and lattice impurities; the mineral impurities include two or more of feldspar, mica, ilmenite, hematite, magnetite, hematite, tourmaline group, and kyanite group; the micro-inclusions and lattice impurities are present inside the quartz ore; the pretreatment includes crushing-screening, scrubbing and desliming, strong magnetic separation, acid reverse flotation, and water washing.

[0033] In this embodiment, the particle size of the product obtained after crushing and screening is -50 to +120 mesh. Crushing and screening the quartz particles to a particle size of -50 to +120 mesh is to ensure the feed particle size of the strong magnetic separation process and to maximize the contact area of ​​the particles in the magnetic field to reduce the speed at which the particles pass through the magnetic field, so as to make the magnetic separation of the material more complete.

[0034] In this embodiment, the solid-liquid mass-volume ratio of quartz ore to scrubbing liquid in the scrubbing and desliming process is 1:3 to 1:8 kg / L, and the scrubbing liquid is one or both of industrial water and oxalic acid solution; the scrubbing and desliming time is 10 min to 60 min, and the scrubbing and desliming is carried out by one or both of mechanical scrubbing and ultrasonic scrubbing.

[0035] Among them, scrubbing and desliming can effectively wash away the impurities, mineral powders and some amorphous impurities attached to the surface, minimizing the impact of these impurities on the surface of quartz particles and affecting the subsequent second-stage flotation effect.

[0036] In this embodiment, the strong magnetic separation is carried out using a superconducting magnetic separator, a high-gradient vertical ring magnetic separator, or a wet strong magnetic separator. The magnetic field strength of the strong magnetic separation is 1.0~4.0T (i.e., 10000Gs~40000Gs), such as 1.1T, 2T, 3.8T, etc.; the magnetic separation cycle is 2~5 times, and the magnetic separation endpoint is when the proportion of magnetic products is less than 0.1% of the feed mass.

[0037] In this embodiment, magnetic separation can be at least one of wet magnetic separation or dry magnetic separation, and magnetic separation can be multi-stage magnetic separation. Wet magnetic separation can use industrial ultrapure water to make the washed water-containing quartz ore particles into a slurry with a concentration of 10~60%. The purpose of magnetic separation is to remove magnetic impurities such as magnetite and hematite from the raw ore, and to minimize the adhesion of these impurities to the surface of the quartz ore particles, so as to affect the effect of subsequent two-stage flotation.

[0038] In this embodiment, the collector used in the acid reverse flotation includes dodecylamine, and the dosage of dodecylamine is 100~200g / t. When carrying out the acid reverse flotation, dilute sulfuric acid or hydrofluoric acid is used to adjust the pH of the quartz ore pulp to 1.5~3, and the mass fraction of the pulp concentration is 10%~30%. The water washing is to wash the concentrate after the acid reverse flotation with deionized water, and the washing endpoint is when the pH of the washing solution is greater than 6.5.

[0039] S2. The first quartz particles are subjected to ammonium salt flotation, water washing and drying to obtain the second quartz particles.

[0040] In this embodiment, the reagents used in the ammonium salt flotation include ammonium salt and collector; the ammonium salt includes one or both of ammonium sulfate and ammonium chloride, and the mass ratio of the ammonium salt to the first quartz particles is 1:3 to 1:50; the collector and its concentration in the flotation solution are 5-60 mg / L of ferrous chloride or ferric chloride, 1-10 mg / L of citric acid or ascorbic acid, and 80-300 mg / L of sodium oleate; the mass fraction of the slurry in the ammonium salt flotation is 10% to 35%; the washing is the washing of the concentrate after ammonium salt flotation with deionized water, and the washing endpoint is when the pH of the washing solution is greater than 6.5; the drying is the dehydration process of the washed product using one of the following methods: electric heating blasting, vacuum drying, and freeze drying, drying until the water content is less than 0.1%, to obtain the second quartz particles.

[0041] Among them, ammonium salts enhance the potential activity of the quartz particle surface, promote the interfacial reaction between minerals and collectors during flotation, improve the efficiency of two-stage flotation, and at the same time, the hydrolysis of ammonium salts makes the solution acidic, eliminating the need to add acid to adjust the pH, thus providing a green flotation method.

[0042] During the purification research, it was found that conventional purification processes have difficulty removing impurity minerals such as hematite, magnetite, hematite, tourmaline group, and kyanite group, or the removal is incomplete. This results in high levels of Al and Ti impurity elements in the final quartz concentrate. Therefore, a targeted flotation process was designed to separate these impurities from quartz.

[0043] S3. The second quartz particles are subjected to segmented calcination, acid washing, water washing and drying to obtain high-purity quartz.

[0044] In this embodiment, the segmented calcination involves mixing the second quartz particles with the additives and then calcining them in a calcination furnace. The segmented calcination refers to dividing the heating process into two stages. In the first stage, the calcination temperature is raised from room temperature to 600°C and held for 30-240 minutes. In the second stage, the calcination temperature is raised from 600°C to 1200°C and held for 30-240 minutes.

[0045] In the first stage of roasting, ammonium chloride and ammonium sulfate decompose completely at 350~500℃. Ammonium chloride decomposes into ammonia and hydrogen chloride gas, and the reaction equation is (1). When NH4Cl is completely decomposed at a temperature ≥337.8℃, NH3 and HCl are obtained, forming a chlorination atmosphere in the sealed tube. Ammonium sulfate undergoes a three-stage decomposition reaction under high temperature conditions. In the first stage of the reaction, ammonium sulfate begins to decompose into solid and undergoes a deammoniation reaction to form ammonium bisulfate and ammonia, and the reaction equation is (2). Since the decomposition temperature of ammonium sulfate is higher than the melting point of ammonium bisulfate, the surface of ammonium sulfate crystals is coated with molten ammonium bisulfate as the reaction proceeds. As the reaction temperature continues to rise, the yield of ammonium bisulfate increases, the content of ammonium sulfate decreases, and the process of heat transfer to ammonium sulfate becomes more difficult as the yield of ammonium bisulfate increases. The higher the temperature, the less obvious the factors controlling the chemical reaction become. When the temperature of the second stage reaction is reached, liquid ammonium bisulfate begins to undergo a dehydration reaction to form ammonium pyrosulfate. The flow of liquid ammonium bisulfate helps to form ammonium pyrosulfate crystals. The reaction equation is (3). When the reaction temperature is further increased, ammonium pyrosulfate will decompose to generate ammonia, nitrogen, sulfur dioxide and water vapor. The reaction equation is (4). However, due to the sealed tube and the complete decomposition of ammonium chloride at this temperature, the concentration of ammonia in the tube increases, which will increase the concentration quotient Q of the chemical reaction in equation (4). Under constant temperature, the equilibrium constant K is fixed. At this time, Q>K, and the reaction tends to proceed in the reverse direction. The reaction kinetics formula for the third stage is (1-(1-α)). 1 / 3 ) 1 / 2 =7.0087×104exp(-93347.9 / (RT))t,is the external diffusion control. The increase in gas concentration in the tube will control the diffusion resistance of the reaction products from the catalyst surface to the main gas flow. In summary, under the synergistic effect of ammonium chloride, ammonium sulfate will tend to decompose to generate ammonium pyrosulfate. Ammonium pyrosulfate and metal oxide can be melted together to obtain soluble sulfate, which will react with the aluminum film on the surface of quartz, causing the quartz to be exposed. At the same time, it will also have a corresponding corrosion effect on the quartz, and more pits will appear on the surface of the quartz, thereby increasing the specific surface area of ​​the quartz mineral particles and making the quartz mineral particles more fully roasted by chlorination.

[0046] ≥337.8℃: NH4Cl=NH3+HCl (1) 246°C-328°C: (NH4)2SO4= (NH4)HSO4+NH3 (2) 328°C-346°C: 2(NH4)HSO4=(NH4)2S2O7+H2O (3) 346°C-430°C: 3(NH4)2S2O7=2NH3+2N2+2SO2+9H2O (4) In this embodiment, the mixing is performed using one of a mixer, an airflow agitator, and a dynamic reaction vessel, with a mixing time of 3-60 minutes. The additives include ammonium sulfate and ammonium chloride, wherein the mass ratio of ammonium sulfate to the second quartz particles is 1:10-1:50, and the mass ratio of ammonium chloride to the second quartz particles is 1:20-1:50. The calcining furnace includes at least one of an atmosphere sintering furnace, a tube furnace, a rotary kiln, and a suspension furnace, and the calcining atmosphere in the calcining furnace is an inert gas, including one or two of nitrogen, helium, and argon.

[0047] In this embodiment, the acid leaching is performed by using a mixed acid solution to leach the roasted product after segmented roasting. The leaching temperature is 80~220℃ and the leaching time is 180~720min. The equipment used for acid leaching is a dynamic acid leaching reactor or a static hydrothermal reactor.

[0048] In this embodiment, the mixed acid solution includes hydrofluoric acid, hydrochloric acid, nitric acid, and sulfuric acid, wherein the concentration of hydrofluoric acid is 0.2~2.0 mol / L, the concentration of hydrochloric acid is 1.2~3.2 mol / L, the concentration of nitric acid is 1.6~4.8 mol / L, and the concentration of sulfuric acid is 0.5~2.0 mol / L; the solid-liquid mass-volume ratio of the calcined product to the mixed acid solution is 1:2~1:5 kg / L.

[0049] In this embodiment, the water washing refers to the product after acid washing with deionized water, and the endpoint of the washing is when the pH of the washing solution is greater than 6.5; the drying refers to the process of dehydrating the product after water washing by one of the following methods: electric heating blasting, vacuum drying, and freeze drying, until the water content is less than 0.1%, to obtain high-purity quartz.

[0050] Exemplary Example 2 This exemplary embodiment provides a high-purity quartz, which can be prepared by the preparation method described in Exemplary Embodiment 1.

[0051] In this embodiment, the SiO2 content in the high-purity quartz is 99.99%~99.999%; the content of aluminum and titanium impurities is less than 15μg / g, which meets the standard for photovoltaic-grade high-purity quartz sand.

[0052] To better understand the exemplary embodiments of the present invention described above, further explanation is provided below with reference to specific examples.

[0053] Examples 1-3 all used sample Q-1 as raw quartz ore to prepare high-purity quartz. For example... Figure 2 As shown, sample Q-1 is a reddish-brown, gravelly quartz-containing mixture with a loose texture and some adhesion.

[0054] Sample Q-1 was crushed and ground to below 100 mesh, and then subjected to powder XRD diffraction analysis. The analysis results are as follows: Figure 3 As shown, the main mineral components of sample Q-1 are quartz, microcline, phlogopite, and kyanite, with quartz accounting for approximately 45%. Sample Q-1 was ground to below 400 mesh, and its chemical composition was analyzed. The results are shown in Table 1.

[0055] Table 1 Chemical composition analysis of sample Q-1 (%)

[0056] Example 1 This example demonstrates the preparation of high-purity quartz using conventional high-purity quartz preparation processes. The preparation method includes the following steps: 1) The raw ore is ground into powder using a rod mill with a zirconium oxide lining, and the grinding time is 90 seconds.

[0057] 2) Screening: A 50-mesh vibrating screen is used for screening. The material under the 50-mesh screen is collected as concentrate, and the product over the 50-mesh screen is collected and ground again to finally obtain quartz ore particles smaller than 50 mesh.

[0058] 3) Scrubbing: The sieved product is scrubbed to remove mud. The scrubbing solution is a 5% oxalic acid solution, and the scrubbing method is mechanical scrubbing.

[0059] 4) Magnetic separation: The quartz ore particles after scrubbing and desliming are subjected to wet magnetic separation, wherein the slurry concentration of the wet magnetic separation is 40% and the magnetic field strength of the wet magnetic separation is 1.5T.

[0060] 5) Acid reverse flotation: Quartz ore particles of -50 to +120 mesh are subjected to flotation. The flotation conditions are as follows: the pH of the pulp is adjusted to 2.5 with hydrofluoric acid, dodecylamine is used as the collector, the pulp concentration is 20%, and the dodecylamine concentration is 200 g / t. Quartz flotation concentrate is obtained.

[0061] 6) Washing: Wash the quartz flotation concentrate obtained in step 5) with deionized water until the pH returns to neutral. Place the washed quartz ore particles into an oven for electric heating and drying.

[0062] 7) Segmented roasting: The dried quartz flotation concentrate from step 6) is subjected to segmented roasting. Ammonium chloride is mixed with and coated with third-stage quartz ore particles at a mass ratio of 1:40. After mixing and coating for 50 minutes, roasting is carried out under inert gas protection. The roasting process is set to a two-stage heating process: the first stage roasting temperature is 600℃ and the holding time is 180 minutes, and the second stage roasting temperature is 1200℃ and the holding time is 180 minutes.

[0063] 8) Acid leaching: The quartz concentrate obtained in step 7) is subjected to mixed acid leaching, wherein the molar concentration of hydrofluoric acid is 1.5 mol / L, the molar concentration of hydrochloric acid is 2.0 mol / L, the concentration of nitric acid is 4.0 mol / L, the concentration of sulfuric acid is 1.5 mol / L, the solid-liquid ratio of acid leaching is 1:4, the acid leaching temperature is 180℃, and the acid leaching time is 600 min.

[0064] 9) Washing and drying: The quartz flotation concentrate obtained in step 8) is washed with deionized water until the pH returns to neutral. The washed quartz particles are then placed in an oven for electric heating and drying to obtain high-purity quartz.

[0065] 10) Testing: The obtained high-purity quartz samples were sent to the National Silicon Inspection Center for testing. Each sample weighed 10g. The testing and judgment were based on JY / T 0567-2020 "General Rules for Inductively Coupled Plasma Emission Spectrometry Analysis". The results are shown in Table 2. It can be seen that after purification using conventionally designed process steps and parameter conditions, the impurity content in the prepared high-purity quartz was 196.81 μg / g. The content of Al and Ti impurities was relatively high, at 104.64 μg / g and 77.76 μg / g respectively, proving that conventional purification methods cannot efficiently remove the aluminum and titanium impurities from this sample.

[0066] Table 2. Detection results of impurity element content in high-purity quartz obtained in Example 1

[0067] Example 2 This example demonstrates the preparation of high-purity quartz using the preparation method described in this invention. The preparation method includes the following steps: 1) Grind the raw ore using a rod mill with a zirconium oxide lining for 90 seconds.

[0068] 2) Screening: A 50-mesh vibrating screen is used for screening. The material under the 50-mesh screen is collected as concentrate, and the product over the 50-mesh screen is collected and ground again to finally obtain quartz ore particles smaller than 50 mesh.

[0069] 3) Scrubbing: The sieved product is scrubbed to remove mud. The scrubbing solution is a 5% oxalic acid solution, and the scrubbing method is mechanical scrubbing.

[0070] 4) Magnetic separation: The quartz ore particles after scrubbing and desliming are subjected to wet magnetic separation, wherein the slurry concentration of the wet magnetic separation is 40% and the magnetic field strength of the wet magnetic separation is 1.5T.

[0071] 5) Acid reverse flotation: Quartz ore particles of 50-120 mesh are subjected to flotation. The flotation conditions are as follows: the pH of the pulp is adjusted to 2.5 with hydrofluoric acid, dodecylamine is used as the collector, the pulp concentration is 20%, and the dodecylamine concentration is 200 g / t. Quartz flotation concentrate is obtained.

[0072] 6) Washing: The quartz flotation concentrate obtained in step 5) is washed with deionized water until the pH returns to neutral to obtain the first quartz particles.

[0073] 7) Ammonium salt flotation: The first quartz particles are subjected to ammonium salt flotation. The flotation reagents used include ammonium salt and collector. The ammonium salt used is ammonium chloride, and the mass ratio of ammonium chloride to the first quartz particles is 1:40. The collector used and its concentration in the flotation solution are 50 mg / L ferrous chloride, 8 mg / L citric acid, and 200 mg / L sodium oleate. The mass fraction of the flotation pulp is 30%. The flotation concentrate is then washed and dried to obtain the second quartz particles.

[0074] 8) Segmented calcination: The second quartz particles obtained in step 7) are calcined in segments. Ammonium sulfate and ammonium chloride are mixed and coated with the second quartz particles, wherein the mass ratio of ammonium sulfate to the second quartz particles is 1:30 and the mass ratio of ammonium chloride to the second quartz particles is 1:40. After mixing and coating for 50 minutes, calcination is carried out under a nitrogen atmosphere. The calcination process is set to a two-stage heating process: the first stage calcination temperature is 600℃ and the holding time is 180 minutes, and the second stage calcination temperature is 1200℃ and the holding time is 180 minutes.

[0075] 9) Acid washing: The roasted product obtained in step 8) is subjected to acid leaching with mixed acid, wherein the molar concentration of hydrofluoric acid is 1.5 mol / L, the molar concentration of hydrochloric acid is 2.0 mol / L, the concentration of nitric acid is 4.0 mol / L, the concentration of sulfuric acid is 1.5 mol / L, the solid-liquid mass ratio of acid leaching (the solid-liquid mass ratio of roasted product to mixed acid solution) is 1:4 kg / L, the acid leaching temperature is 180℃, and the acid leaching time is 600 min.

[0076] 10) Washing and drying: The acid leaching product obtained in step 9) is washed with deionized water until the pH returns to neutral. The high-purity quartz particles after rinsing are placed in an oven for electric heating and drying to obtain high-purity quartz.

[0077] 11) Testing: The obtained high-purity quartz samples were sent to the National Silicon Inspection Center for testing. Each sample weighed 10g. The testing and judgment were based on JY / T 0567-2020 "General Rules for Inductively Coupled Plasma Emission Spectrometry Analysis". The results are shown in Table 3. After purification using the process steps and parameters provided by this invention, the total impurity content in the prepared high-purity quartz was 33.06 μg / g, a reduction of 163.75 μg / g compared to conventional purification methods, demonstrating a significant purification effect. Specifically, the Al and Ti impurities were reduced by 93.07 μg / g and 64.24 μg / g, respectively, proving that the preparation method described in this invention has a significant removal effect on aluminum and titanium impurities in quartz.

[0078] Table 3 Comparison of impurity element content in high-purity quartz prepared in this example and high-purity quartz prepared in Example 1

[0079] Example 3 This example demonstrates the preparation of high-purity quartz using the preparation method described in this invention. The preparation method includes the following steps: 1) The raw ore is ground into powder using a rod mill with a zirconium oxide lining, and the grinding time is 90 seconds.

[0080] 2) Screening: A 50-mesh vibrating screen is used for screening. The material under the 50-mesh screen is collected as concentrate, and the product over the 50-mesh screen is collected and ground again to finally obtain quartz ore particles smaller than 50 mesh.

[0081] 3) Scrubbing: The sieved product is scrubbed to remove mud. The scrubbing solution is a 5% oxalic acid solution, and the scrubbing method is mechanical scrubbing.

[0082] 4) Magnetic separation: The quartz ore particles after scrubbing and desliming are subjected to wet magnetic separation, wherein the slurry concentration of the wet magnetic separation is 40% and the magnetic field strength of the wet magnetic separation is 1.5T.

[0083] 5) Acid reverse flotation: Quartz ore particles of 50-120 mesh are subjected to flotation. The flotation conditions are as follows: the pH of the pulp is adjusted to 2.5 with hydrofluoric acid, dodecylamine is used as the collector, the pulp concentration is 20%, and the dodecylamine concentration is 200 g / t. Quartz flotation concentrate is obtained.

[0084] 6) Washing: The quartz flotation concentrate obtained in step 5) is washed with deionized water until the pH returns to neutral to obtain the first quartz particles.

[0085] 7) Ammonium salt flotation: The first quartz particles are subjected to ammonium salt flotation. The flotation reagents used include ammonium salt and collector. The ammonium salt used is ammonium chloride, and the mass ratio of ammonium chloride to the first quartz particles is 1:20. The collector used and its concentration in the flotation solution are ferrous chloride 20 mg / L, citric acid 5 mg / L, and sodium oleate 100 mg / L. The mass fraction of the flotation pulp is 20%. The flotation concentrate is then washed and dried to obtain the second quartz particles. Figure 4 A comparison diagram of tailings and concentrate after ammonium salt flotation is shown.

[0086] 8) Segmented calcination: The second quartz particles obtained in step 7) are subjected to segmented calcination. Ammonium sulfate and ammonium chloride are mixed and coated with the second quartz particles, with a mass ratio of ammonium sulfate to third quartz particles of 1:20 and a mass ratio of ammonium chloride to third quartz particles of 1:20. After mixing and coating for 10 minutes, calcination is carried out under a nitrogen atmosphere. The calcination process is set to a two-stage heating process: the first stage calcination temperature is 600℃, and the holding time is 60 minutes; the second stage calcination temperature is 1200℃, and the holding time is 60 minutes.

[0087] 9) Acid washing: The roasted product obtained in step 8) is subjected to acid leaching with mixed acid, wherein the molar concentration of hydrofluoric acid is 0.5 mol / L, the molar concentration of hydrochloric acid is 2.0 mol / L, the concentration of nitric acid is 2.0 mol / L, the concentration of sulfuric acid is 1.0 mol / L, the solid-liquid mass ratio of acid leaching (the solid-liquid mass ratio of roasted product to mixed acid solution) is 1:3 kg / L, the acid leaching temperature is 120℃, and the acid leaching time is 360 min.

[0088] 10) Washing and drying: The acid leaching product obtained in step 9) is washed with deionized water until the pH returns to neutral. The rinsed quartz ore particles are then placed in an oven for electrically heated drying to obtain high-purity quartz. Figure 5 The image shown is a photograph of the prepared high-purity quartz.

[0089] 11) Testing: The obtained high-purity quartz samples were sent to the National Silicon Inspection Center for testing. Each sample weighed 10g. The testing and judgment were based on JY / T 0567-2020 "General Rules for Inductively Coupled Plasma Emission Spectrometry Analysis". The results are shown in Table 4. After purification using the process steps and parameters provided in this application, the impurity content in the prepared high-purity quartz was 24.93 μg / g, a reduction of 171.88 μg / g compared to conventional purification methods, demonstrating a significant purification effect. Specifically, the Al and Ti impurities were reduced by 96.19 μg / g and 66.31 μg / g, respectively, proving that the preparation method described in this invention has a good and significant removal effect on aluminum and titanium impurities in quartz.

[0090] Table 4 Comparison of impurity element content in high-purity quartz prepared in this example and high-purity quartz prepared in Example 1

[0091] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz, characterized in that, The method includes the following steps: 1) Pre-treat the quartz ore to obtain the first quartz particles; 2) The first quartz particles are subjected to ammonium salt flotation, water washing and drying to obtain the second quartz particles; 3) The second quartz particles are subjected to staged roasting, acid washing, water washing and drying to obtain high-purity quartz.

2. The method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz according to claim 1, characterized in that, The quartz ore includes at least one of natural crystal, granite pegmatite, vein quartz, and quartzite; the quartz ore contains mineral impurities of aluminum and titanium, micro-inclusions, and lattice impurities; the mineral impurities include two or more of feldspar, mica, ilmenite, hematite, magnetite, hematite, tourmaline group, and kyanite group; the micro-inclusions and lattice impurities are present inside the quartz ore; the pretreatment includes crushing-screening, scrubbing and desliming, strong magnetic separation, acid reverse flotation, and water washing.

3. The method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz according to claim 2, characterized in that, The particle size of the product obtained after crushing and screening is -50 to +120 mesh; the solid-liquid ratio of quartz ore to scrubbing liquid in the scrubbing and desliming process is 1:3 to 1:8 kg / L, the scrubbing and desliming time is 10 min to 60 min, and the scrubbing and desliming is carried out by one or both of mechanical scrubbing and ultrasonic scrubbing; the strong magnetic separation is carried out by a superconducting magnetic separator, a high-gradient vertical ring magnetic separator, or a wet strong magnetic separator, the magnetic field strength of the strong magnetic separation is 1.0 to 4.0 T, the magnetic separation cycle is 2 to 5 times, and the magnetic separation endpoint is when the proportion of magnetic product is less than 0.1% of the feed mass.

4. The method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz according to claim 2, characterized in that, The collector used in the acid reverse flotation includes dodecylamine, and the dosage of dodecylamine is 100~200g / t. When carrying out the acid reverse flotation, the pH of the quartz ore pulp needs to be adjusted to 1.5~3 with dilute sulfuric acid or hydrofluoric acid, and the mass fraction of the pulp concentration is 10%~30%. The water washing is to wash the concentrate after the acid reverse flotation with deionized water, and the washing endpoint is when the pH of the washing solution is greater than 6.

5.

5. The method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz according to claim 1, characterized in that, The reagents used in the ammonium salt flotation in step 2) include ammonium salts and collectors; the ammonium salts include one or both of ammonium sulfate and ammonium chloride, and the mass ratio of the ammonium salts to the first quartz particles is 1:3 to 1:50; the collectors and their concentrations in the flotation solution are 5-60 mg / L for ferrous chloride or ferric chloride, 1-10 mg / L for citric acid or ascorbic acid, and 80-300 mg / L for sodium oleate; the mass fraction of the pulp used in the ammonium salt flotation is 10% to 35%; The water washing refers to washing the concentrate after ammonium salt flotation with deionized water, and the washing endpoint is when the pH of the washing solution is greater than 6.5; the drying refers to the process of dehydrating the product after water washing by one of the following methods: electric heating blasting, vacuum drying and freeze drying, until the water content is less than 0.1%, to obtain the second quartz particles.

6. The method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz according to claim 1, characterized in that, The segmented calcination mentioned in step 3) refers to the process of mixing the second quartz particles with the additives and then calcining them in a calcination furnace in stages. The segmented calcination means that the heating process is divided into two stages. In the first stage, the calcination temperature is raised from room temperature to 600°C and held for 30 to 240 minutes. In the second stage, the calcination temperature is raised from 600°C to 1200°C and held for 30 to 240 minutes.

7. The method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz according to claim 6, characterized in that, The mixing is carried out using one of a mixer, an airflow agitator, and a dynamic reaction vessel, with a mixing time of 3-60 minutes. The additives include ammonium sulfate and ammonium chloride, wherein the mass ratio of ammonium sulfate to the second quartz particles is 1:10-1:50, and the mass ratio of ammonium chloride to the second quartz particles is 1:20-1:

50. The calcining furnace includes at least one of an atmosphere sintering furnace, a tube furnace, a rotary kiln, and a suspension furnace, and the calcining atmosphere in the calcining furnace is an inert gas, including one or two of nitrogen, helium, and argon.

8. The method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz according to claim 1, characterized in that, The acid washing described in step 3) involves using a mixed acid solution to leach the roasted product after segmented roasting. The leaching temperature is 80~220℃ and the leaching time is 180~720min. The mixed acid solution comprises hydrofluoric acid, hydrochloric acid, nitric acid, and sulfuric acid, wherein the concentration of hydrofluoric acid is 0.2~2.0 mol / L, the concentration of hydrochloric acid is 1.2~3.2 mol / L, the concentration of nitric acid is 1.6~4.8 mol / L, and the concentration of sulfuric acid is 0.5~2.0 mol / L; the solid-liquid ratio of the calcined product to the mixed acid solution is 1:2~1:5 kg / L.

9. The method for effectively removing aluminum and titanium components from quartz ore to prepare high-purity quartz according to claim 1, characterized in that, The water washing mentioned in step 3) refers to the product after acid washing with deionized water. The endpoint of the washing is when the pH of the washing solution is greater than 6.

5. The drying refers to the process of dehydrating the product after water washing by one of the following methods: electric heating blasting, vacuum drying, and freeze drying, until the water content is less than 0.1%, to obtain high-purity quartz.

10. A high-purity quartz, characterized in that, The high-purity quartz is prepared by the preparation method according to any one of claims 1-9; The high-purity quartz contains 99.99% to 99.999% SiO2; the content of aluminum and titanium impurities is less than 15 μg / g, meeting the standard for photovoltaic-grade high-purity quartz sand.

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