A method for completely removing calcium from high-purity quartz during purification

Abstract

The invention discloses a method for comprehensively removing calcium in the process of purifying high-purity quartz: the method is characterized by comprising the following steps: a. adding a medium to the quartz sand after magnetic separation to scrub it at a certain liquid-solid ratio, and washing the scrubbed fine sand with deionized water; b. adding a flotation collector to the quartz sand after drug removal treatment, floating out the calcium-containing minerals as tailings through a flotation machine, and washing the flotation fine sand with deionized water; c. mixing the flotation fine sand with mixed acid and deionized water, putting it into a reactor at a certain liquid-solid ratio for high-temperature pickling, and washing the pickled fine sand with deionized water after the pickling is completed; d. utilizing the difference in specific gravity, using an ultrasonic classifier to remove the calcium fluoride impurities generated after pickling, and obtaining the final fine sand. The advantages of the invention are that the natural calcium-containing mineral impurities and the introduced calcium-containing impurities in the quartz sand sample can be comprehensively removed, the pertinence is strong, the removal efficiency is high, and the calcium content of the high-purity quartz sand can be significantly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of high-purity quartz sand beneficiation and purification, and relates to a method for comprehensively removing calcium elements in the process of high-purity quartz purification. Background Art

[0002] High-purity quartz sand is the only raw material for quartz products such as quartz crucibles, quartz tubes, quartz balls, and quartz boats. These products are indispensable consumables in the photovoltaic and semiconductor industries and are used in all aspects of silicon wafer processing. The total impurity content of high-purity quartz sand is extremely low, and there are strict standards for the content of individual elements. Among them, excessive calcium content is one of the important issues restricting the development of my country's high-purity quartz sand industry. Different quartz products require different calcium content requirements. Generally speaking, it is generally not higher than 1.5ppm. Excessive calcium content will affect the optical properties, thermal stability and other indicators of the product, and will also reduce the service life of the product. The existing mineral processing and purification processes are unable to achieve targeted removal of calcium elements, which means that in order to obtain high-quality, high-purity quartz sand, production companies have extremely stringent requirements on the endowment of quartz ore. However, there are very few high-quality high-purity quartz ores in my country. With the current purification technology and prospecting progress, there is basically no high-purity quartz raw material that can be industrialized. This forces high-purity quartz sand production companies to import high-quality raw materials from abroad. Therefore, breaking through the existing bottleneck of mineral processing and purification technology and developing a targeted removal process for calcium elements are important supports for ensuring the healthy development of my country's photovoltaic and semiconductor industries.

[0003] The calcium element in high-purity quartz sand is divided into two types: native and introduced. The native calcium element is present in the associated gangue minerals, such as calcite and fluorite. At this stage, this part of the gangue minerals is mainly removed by flotation. Relying on the difference in the properties of the gangue minerals and the quartz surface interface, oleic acid collectors are used to achieve the selective floating of calcium-containing minerals. However, the selectivity of such agents is weak, and due to their poor water solubility, they are extremely sensitive to the slurry temperature, and often cannot achieve comprehensive removal of calcium-containing minerals; the introduced calcium element is mainly caused by hydrofluoric acid. Due to the property of hydrofluoric acid that can dissolve silicon dioxide, hydrofluoric acid is inevitable in the field of quartz beneficiation and purification. Hydrofluoric acid easily reacts chemically with native calcium-containing minerals to generate insoluble calcium fluoride impurities, which are extremely difficult to remove. Existing research and processes cannot have a significant removal effect on the acquired calcium fluoride impurities, resulting in the problem of excessive calcium in some quartz ores after beneficiation and purification. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of excessive calcium in high-purity quartz sand in the prior art and to propose a method for comprehensively removing calcium in the process of purifying high-purity quartz.

[0005] A method for comprehensively removing calcium in a high-purity quartz purification process, characterized in that it comprises the following steps: a. Add the magnetically separated quartz sand into the medium and scrub it at a certain liquid-to-solid ratio, and use deionized water to wash the scrubbed sand; b. Adding a flotation collector to the scrubbed sand after washing and drug removal, floating the calcium-containing minerals through a flotation machine and discarding them as tailings, and washing the obtained flotation sand with deionized water; c. Mix the washed flotation concentrate with mixed acid and deionized water, put it into a reactor at a certain liquid-to-solid ratio for high-temperature pickling, and wash the obtained pickled concentrate with deionized water after the pickling is completed; d. Utilize the difference in specific gravity and use an ultrasonic classifier to classify the pickling concentrate to remove the calcium fluoride impurities produced during the pickling process and obtain the final concentrate.

[0006] On the basis of the above technical solutions, there are the following further technical solutions: In step a, the scrubbing medium is one or a combination of hydrochloric acid, sulfuric acid, citric acid, and nitric acid, and the scrubbing concentration is 40-60%, which can achieve efficient cleaning of the quartz sand surface while avoiding the introduction of calcium fluoride impurities in this process.

[0007] The flotation in step b is neutral reverse flotation, the flotation concentration is 25-35%, the flotation adopts the new collector EP-3, the synthesis method is to use the higher alcohol with a carbon chain length of 6-12 and pyrophosphoric acid to heat and react to generate phosphate ester compounds, the molar ratio is 1:0.8-1.5, the synthesis is completed under normal pressure environment, the synthesis temperature is 60-80°C, the time is 6h-12h, and the dosage is 200-400g / t.

[0008] In step c, the solid weight ratio of the pickling liquid (the weight ratio of the flotation concentrate to the mixed acid and deionized water) is 1:0.8-2, and the mixed acid is one or more of hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, citric acid, and oxalic acid, and the dosage is 100-200 kg / t.

[0009] In the step d, the ultrasonic hydraulic classifier has an upward water flow of 5-20 L / h, an ultrasonic frequency of 20-60 KHz, and a classification time of 10-60 min.

[0010] Beneficial effects of the present invention:

[0011] 1. The present invention provides a method for comprehensively removing calcium elements during the purification process of high-purity quartz. Through the scrubbing-flotation-pickling-ultrasonic purification process, while achieving efficient flotation removal of calcium-containing minerals, the introduction of calcium fluoride impurities during the purification process of high-purity quartz is solved to the greatest extent.

[0012] 2. In the present invention, the surface of the quartz sand particles is first cleaned by a scrubbing process before the flotation process, which greatly improves the flotation effect. In addition, hydrofluoric acid is not used as the scrubbing medium, which avoids its reaction with calcium-containing minerals to generate a large amount of calcium fluoride impurities that are difficult to remove.

[0013] 3. In the present invention, the flotation process adopts a new type of floating calcium collector, the synthetic raw materials are easy to obtain and the production process is simple. Compared with traditional collectors such as oleic acid, the removal rate of calcium-containing minerals is higher.

[0014] 4. In the present invention, the pickling process adopts a mixed acid combination mainly composed of hydrofluoric acid, which can open the crack channels and improve the pickling effect by relying on the corrosiveness of hydrofluoric acid on silicate minerals.

[0015] 5. In the present invention, a new type of ultrasonic classifier is used to remove a small amount of calcium fluoride impurities introduced by hydrofluoric acid. Ultrasonic waves can effectively shake calcium fluoride impurities out of the cracks in quartz sand, and utilize the difference in specific gravity between quartz sand and calcium fluoride to remove calcium fluoride through hydraulic action. In addition, during the purification process, the ultrasonic classifier can keep the quartz sand in a dispersed state at all times, effectively preventing the calcium fluoride impurities from being blocked by quartz sand particles when floating up. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a process flow chart of the present invention. Specific implementation plan

[0017] Implementation Case 1 This example uses vein quartz from northern India as raw material (1) High-quality vein quartz raw materials without obvious iron contamination are hand-selected, and the particle size range is controlled to -0.45mm+0.1mm through the crushing-screening-magnetic separation pre-treatment process, and some impurity minerals and mechanical iron are removed to obtain preliminary purified quartz sand.

[0018] (2) The magnetic separation concentrate obtained in step (1) is mixed with hydrochloric acid and deionized water in a scrubbing tank, wherein the amount of hydrochloric acid used is 30 kg / t, the slurry concentration is 50%, the scrubbing time is 30 min, and the scrubbing speed is 400 r / min, which can preliminarily remove the impregnation iron impurities on the surface of the quartz sand and clean the surface of the quartz sand particles. After scrubbing, the slurry is deacidified with deionized water, the deacidification concentration is controlled to be 25%, the sedimentation time is 1 min, and the process is repeated 5 times to obtain scrubbed concentrate.

[0019] (3) The scrubbed concentrate obtained in step (2) is mixed with deionized water in a flotation tank and fixed on a 0.75L laboratory small-scale pneumatic flotation machine, wherein the pulp concentration is 30%, the flotation machine speed is 1999r / min, 200g / t of new flotation collector EP-3 is added, the stirring time is 2min, and the scraping time is 3min. During the flotation process, the collector EP-3 can be adsorbed on the calcium-containing mineral, making it hydrophobic and floating. After flotation, the quartz sand settled at the bottom of the flotation tank is poured out for deacidification treatment, and the deacidification concentration is controlled to be 25%, and the sedimentation time is 1min. Repeat 5 times to obtain flotation concentrate. The production process of EP-3 is to take a higher alcohol with a carbon chain length of 6-12 and pyrophosphoric acid in a molar ratio of 1:0.8~1.5, respectively, set the synthesis temperature to 60-80℃ under normal pressure, take it out after 6h-12h, and pour it into a reagent bottle after the temperature drops to room temperature.

[0020] (4) The flotation concentrate obtained in step (3) is mixed with deionized water in a polytetrafluoroethylene tank and placed in a reactor, wherein the amount of hydrofluoric acid + oxalic acid is 200 kg / t, the liquid-to-solid ratio is 1:2, the pickling temperature is 80°C, and the pickling time is 12 h. Hydrofluoric acid can expand the cracks on the surface of the quartz sand, enhance the pickling effect, and achieve deep removal of impurity elements. After the pickling is completed, the quartz sand in the reactor is deacidified, the deacidification concentration is controlled to be 25%, the sedimentation time is 1 min, and the process is repeated 6 times to obtain pickled concentrate.

[0021] (5) The pickled fine sand obtained in step (4) is placed in an ultrasonic classifier, the rising water flow is controlled to be 10 L / h, the ultrasonic frequency is set to 40 kHz, and the purification time is 30 min. The calcium fluoride impurities can be effectively shaken out from the cracks of the quartz sand, and the calcium fluoride can be removed by hydraulic action by utilizing the difference in specific gravity between quartz sand and calcium fluoride. During the purification process, the quartz sand can be kept dispersed at all times, and finally a high-purity quartz sand fine sand is obtained.

[0022] The index results of the vein quartz before and after mineral processing and purification are shown in Table 1, the comparison of flotation agent effects is shown in Table 2, and the comparison of ultrasonic purification effects is shown in Table 3.

[0023] Table 1 Comparison of indicators before and after purification of vein quartz in northern India (mg·kg -1

[0024]

[0025] Implementation Case 2 This example uses Pakistani vein quartz as raw material Using the same method as in Example 1, the index results of the vein quartz before and after mineral processing and purification are shown in Table 4, the comparison of flotation agent effects is shown in Table 5, and the comparison of ultrasonic purification effects is shown in Table 6.

[0026] Table 4 Comparison of Pakistani vein quartz indicators before and after purification / mg·kg -1

[0027] Implementation Case 3 In this example, Xinjiang Altay pegmatite quartz is used as raw material Using the same method as in Example 1, the index results of the pegmatite quartz before and after mineral processing and purification are shown in Table 7, the comparison of flotation agent effects is shown in Table 8, and the comparison of ultrasonic purification effects is shown in Table 9.

[0028] Table 7 Comparison of Xinjiang pegmatite quartz indicators before and after purification / mg·kg -1

[0029] The above embodiments are only descriptions of preferred examples of the present invention and do not limit the scope of the present invention. Without departing from the principle of the present invention, all forms of changes should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for comprehensively removing calcium from a high-purity quartz purification process, characterized in that The following steps are involved: a. Add the magnetically separated quartz sand into the medium and scrub it at a certain liquid-to-solid ratio, and use deionized water to wash the scrubbed sand; b. Adding a flotation collector to the scrubbed sand after washing and drug removal, floating the calcium-containing minerals through a flotation machine and discarding them as tailings, and washing the obtained flotation sand with deionized water; c. Mixing the washed flotation concentrate with mixed acid and deionized water, and then placing the mixed acid in a reactor for high-temperature pickling. After the pickling is completed, the obtained pickled concentrate is washed with deionized water; d. Use an ultrasonic classifier to classify the pickling concentrate, and use the difference in specific gravity to remove the calcium fluoride impurities produced during the pickling process to obtain the final concentrate.

2. The method for comprehensively removing calcium from high-purity quartz during purification according to claim 1, characterized in that: In step a, the scrubbing medium is one or a combination of hydrochloric acid, sulfuric acid, citric acid, and nitric acid, and the scrubbing concentration is 40-60%.

3. The method for comprehensively removing calcium from high-purity quartz during purification according to claim 1, characterized in that: The flotation in S2 is neutral reverse flotation, the flotation concentration is 25-35%, and the flotation adopts a new collector. The synthesis method is to use a higher alcohol with a carbon chain length of 6-12 and pyrophosphoric acid to heat and react to generate a phosphate ester compound, and the dosage is 200-400g / t.

4. The method for comprehensively removing calcium from high-purity quartz during purification according to claim 1, characterized in that: In the step c, the weight ratio of the flotation concentrate to the mixed acid and deionized water is 1:0.8-2, and the mixed acid is one or a combination of hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, citric acid, and oxalic acid, and the dosage is 100-200 kg / t.

5. The method for comprehensively removing calcium from high-purity quartz during purification according to claim 1, characterized in that: In the step d, the water flow rate of the ultrasonic classifier is 5-20 L / h, the ultrasonic frequency is 20-60 KHz, and the classification time is 10-60 min.

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