Method for manufacturing high-purity quartz sand by liquid-phase discharge method and device therefor

Abstract

The application relates to a method for manufacturing high-purity quartz sand by a liquid-phase discharge method and a device thereof, and belongs to the technical field of quartz sand purification methods.The technical scheme is characterized in that the method comprises the following steps: S1, pretreatment; S2, liquid-phase discharge purification; S3, neutralization treatment; S4, dehydration; and S5, dehydroxylation; the device comprises an electrolytic cell, a reaction container and a direct-current pulse power source, the electrolytic cell is internally provided with an alkaline electrolyte; the reaction container is provided with a filter hole, one end of the electrolytic cell is internally provided with a plate-type graphite electrode, the plate-type graphite electrode is connected with a negative electrode of the direct-current pulse power source, the reaction container is internally provided with a tungsten rod electrode, and the tungsten rod electrode is connected with a positive electrode of the direct-current pulse power source; the prepared high-purity quartz sand is not easy to adsorb small particles on the surface, has high purity, and has good removal effects on metal elements such as aluminum, titanium and lithium.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quartz sand purification methods, and particularly relates to a method for manufacturing high-purity quartz sand by a liquid-phase discharge method and a device thereof. BACKGROUND

[0002] High-purity quartz sand refers to quartz sand with a silicon dioxide content of greater than 99.99%, which can be applied to the fields of photovoltaic new energy, national defense and military industry, and electronic semiconductors, and is an industrial raw material with strategic significance.

[0003] At present, the main method for purifying quartz sand on the market is to treat it by chemical processes such as acid leaching and alkali leaching. For details, reference can be made to the following documents. A Chinese patent application file with the application publication number CN112919478A discloses a preparation method of high-purity quartz, which comprises the following steps: alkali leaching: mixing the screened quartz ore with a sodium hydroxide solution for heat leaching; acid leaching: mixing the quartz after alkali leaching with a hydrochloric acid solution for heat leaching, and then washing with water, filtering and drying to obtain high-purity quartz. A Chinese patent with the authorization publication number CN114477188B discloses a purification method of high-purity quartz sand, which comprises the following operations: soaking quartz sand in a chemical solution, the chemical solution comprising an acid solution and / or an alkali solution, and then separating and removing the chemical solution after soaking; soaking the quartz sand in a silicon dioxide colloid, and then separating and removing the silicon dioxide colloid after soaking; and obtaining the purified quartz sand.

[0004] The process of acid leaching and alkali leaching for purifying quartz sand can achieve good removal effect on copper, iron, calcium and other elements in the quartz sand, but the removal effect on aluminum, titanium, lithium and other metal elements is not ideal, because these impurity elements have a low content and exist in inclusions, and are easy to form lattice impurities ； On the other hand, during the acid leaching and alkali leaching processes, small metal salt ions are generated, which are easy to be adsorbed on the surface of quartz sand particles, and cannot be cleaned by the conventional ultrasonic oscillation water washing method, thereby affecting the purity of high-purity quartz sand. SUMMARY

[0005] One of the purposes of the present application is to provide a method for manufacturing high-purity quartz sand by a liquid-phase discharge method, which can prevent small particles from being adsorbed on the surface of the prepared high-purity quartz sand, has high purity, and has good removal effect on aluminum, titanium, lithium and other metal elements.

[0006] The above technical purpose of the present application is achieved by the following technical solution: a method for manufacturing high-purity quartz sand by a liquid-phase discharge method, comprising the following method steps:

[0007] Step S1, pretreatment, after the quartz sand is magnetically selected, the quartz sand is soaked in a mixed acid treatment liquid for 6-8 hours, and after being taken out, the quartz sand is washed with ultrapure water to obtain pretreated sand;

[0008] Step S2, liquid phase discharge purification, the pretreated sand is put into an insulating material reaction container, a filter hole is arranged on the reaction container, the diameter of the filter hole is smaller than the diameter of the quartz sand selected, the reaction container is put into an electrolytic cell containing an alkaline electrolyte, the alkaline electrolyte is used to immerse the pretreated quartz sand in the reaction container, a cathode connected to the negative pole of a power supply is inserted into the electrolytic cell, and an anode connected to the positive pole of the power supply is inserted into the reaction container, the power supply is turned on, a pulse direct current voltage of 15-45V is applied to the electrolytic cell, and after treatment for 30-120 minutes, the quartz sand in the reaction container is taken out for standby;

[0009] Step S3, neutralization treatment, the quartz sand treated in step S2 is added into a combined acid neutralization liquid for immersion washing for 30-60 minutes, and then taken out and washed with ultrapure water;

[0010] Step S4, dehydration, the quartz sand treated in step S3 is added with a coupling agent and uniformly mixed, and then centrifugal dehydration is performed to remove the water contained in the quartz sand;

[0011] Step S5, dehydroxylation, the quartz sand treated in step S4 is heated at 950-1050℃ for 30-50 minutes to obtain the high-purity quartz sand.

[0012] Through the above technical solution, the surface of the quartz sand is first corroded by the mixed acid to remove the metal impurities on the surface of the quartz sand which are easy to react with the acid, and then the quartz sand is put into the electrolytic cell of the alkaline electrolyte, and the alkaline electrolyte is used to further corrode and strip the impurities on the quartz sand. Under the action of the pulse voltage, a large number of hydrogen bubbles are formed on the surface of the anode in the electrolytic cell, and then a bubble layer is formed to wrap the anode, so that the alkaline electrolyte and the anode are insulated in a short time, a potential gradient is formed to form an electric field, and when the field strength exceeds the critical value, an electric shock occurs, that is, the bubble layer is broken down, and a spark discharge is generated. The high temperature generated in the spark discharge moment acts on the surface of the quartz sand, the impurities on the surface of the quartz sand are stripped by thermal stress, and cracks are generated on the surface of the quartz sand, so that the impurities in the quartz sand can be etched better; the impurities and metal ions stripped from the quartz sand have a particle size much smaller than that of the quartz sand, and under the combined action of electric charge, gravity and water flow, they pass through the filter hole of the reaction container, the large particles gradually deposit at the bottom of the electrolytic cell, and the small metal cations are attracted and gathered near the cathode, so that the surface of the quartz sand is not easy to adsorb small particles; after the liquid phase discharge purification of the quartz sand is completed, the quartz sand is immersed and washed with a combined acid neutralization liquid, on the one hand, the residual alkali on the surface of the quartz sand is neutralized, and on the other hand, the cracks generated on the surface of the quartz sand during the liquid phase discharge purification process further etch and purify the quartz sand.

[0013] Preferably, in step S2, a pressure nozzle is arranged at the lower part of the anode, and the quartz sand near the discharge end of the anode is impacted by the water flow of the pressure nozzle to make the quartz sand roll and flow.

[0014] Through the above technical solution, the water flow sprayed by the pressure nozzle impacts the quartz sand to make the quartz sand roll and flow, so that the quartz sand can more uniformly and efficiently receive the discharge stripping effect of the anode.

[0015] Preferably, the pressure nozzle is connected with a circulating water pump, and the alkaline electrolyte at the cathode is pumped to the vicinity of the anode by the circulating water pump.

[0016] Through the above technical solution, with the discharge of the anode, the alkaline electrolyte in the alkaline electrolyte reacts with the impurities in the quartz sand, so that the alkaline electrolyte near the anode has a lower concentration. The alkaline electrolyte at the cathode is pumped to the anode by the circulating water pump, so that the alkaline electrolyte near the anode is maintained at a relatively constant concentration range during the discharge process.

[0017] Preferably, the mixed acid treatment liquid comprises 3-5wt% of HF, 0-2wt% of H2SO4, 8-14wt% of HCl, and 0.5-1wt% of hydroxyethylidene diphosphonic acid.

[0018] Through the above technical solution, the HF in the mixed acid treatment liquid can well corrode the surface of the quartz sand, and then the H2SO4 and HCl can efficiently react with metal impurities such as Fe, Ca, Mg, and Al on the newly exposed surface to generate metal salt ions; the hydroxyethylidene diphosphonic acid can form complexes with various metal ions such as iron, copper, aluminum, and zinc, and play a role in precipitation conversion in the acid solution. The corrosion of H2SO4 in the mixed acid treatment liquid is relatively strong, but the concentration is relatively low, so the reaction finally generates chlorides and complexes with high solubility. At the same time, the hydroxyethylidene diphosphonic acid plays a film-forming role on the surface of the quartz sand in the subsequent liquid phase discharge purification process, thereby buffering the liquid phase discharge process, reducing excessive removal, balancing the chemical corrosion and discharge removal process, and thus achieving a better purification effect on the quartz sand.

[0019] Preferably, the alkaline electrolyte comprises 7-10wt% of NaOH, 14-20wt% of KOH, and 2-5wt% of sodium dodecyl sulfate.

[0020] Through the above technical solution, the ionization degree of KOH is higher than that of NaOH, and its alkalinity is stronger. If the initial OH - concentration of the alkaline electrolyte is too low, its corrosion is too weak; if it is too high, more insoluble precipitates will be formed. By compounding NaOH and KOH, the OH -The quartz sand can be discharged and purified well by keeping the concentration range constant; sodium dodecyl sulfonate as a surfactant improves the surface wettability of the anode, reduces the surface tension, significantly reduces the thickness of the air layer, reduces the critical voltage of the liquid phase discharge, and thus improves the removal efficiency, achieving the purpose of purification.

[0021] Preferably, the combined acid neutralizing liquid comprises 0.5-1wt% hydrochloric acid and 0.5-1wt% oxalic acid.

[0022] Through the above technical solution, hydrochloric acid as a pH regulator, plays a role in neutralizing the alkali solution, adjusting the pH of the solution, oxalic acid provides oxalate, as a ligand of metal ion complex, converts some slightly soluble precipitates formed in the alkaline environment into soluble chelates.

[0023] Preferably, the coupling agent is a silane coupling agent.

[0024] Through the above technical solution, the hydrophilic end of the silane coupling agent is combined with the OH - The hydrophobic end is outward, and a monolayer is formed on the surface of the quartz sand, the surface energy of the quartz sand is reduced, the ability of the particles to adsorb impurities and fine powder in the air is reduced, and the tendency of the particles to attract each other is reduced, so that the quartz sand can be dehydrated more effectively and the adsorption of fine particles by the quartz sand is effectively reduced.

[0025] Preferably, the cathode is a plate graphite electrode, and the anode is a tungsten rod electrode with a tapered end.

[0026] Through the above technical solution, graphite has good corrosion resistance to most acids, bases and organic solvents, and has a large contact area with the alkaline electrolyte, and has good discharge effect; tungsten has good chemical stability and good corrosion resistance to most acids, bases and organic solvents, and by setting the end of the tungsten rod electrode to be tapered, the discharge effect is further improved.

[0027] Another object of the present application is to provide a device for manufacturing high-purity quartz sand by liquid phase discharge method, which can effectively remove aluminum, titanium, lithium and other metal elements.

[0028] A device for manufacturing high-purity quartz sand by liquid phase discharge method, comprising an electrolytic cell, a reaction vessel and a direct current pulse power supply, the electrolytic cell is filled with an alkaline electrolyte; the reaction vessel is provided with a filter hole, one end of the electrolytic cell is provided with a plate graphite electrode, the plate graphite electrode is connected with the negative electrode of the direct current pulse power supply, the reaction vessel is provided with a tungsten rod electrode, and the tungsten rod electrode is connected with the positive electrode of the direct current pulse power supply.

[0029] By the technical scheme, when the quartz sand is subjected to discharge purification by the device for manufacturing high-purity quartz sand by using liquid-phase discharge method, the quartz sand is put into the reaction container, and then the reaction container is put into the electrolytic cell, so that the alkaline electrolyte immerses the quartz sand in the reaction container, then the plate graphite electrode and the tungsten rod electrode are connected with the negative pole and the positive pole of the direct-current pulse power source respectively, a large number of hydrogen bubbles are formed on the surface of the tungsten rod electrode by pulse discharge, and then a bubble layer is formed to wrap the anode, so that the alkaline electrolyte and the anode form insulation in a short time, a potential gradient is formed to form an electric field, and when the field strength exceeds a critical value, an electric shock occurs, i.e. the bubble layer is broken down, spark discharge is generated, the high temperature generated in the spark discharge moment acts on the surface of the quartz sand, the impurities on the surface of the quartz sand are stripped by thermal stress, and cracks are generated on the surface of the quartz sand, so that the impurities in the quartz sand can be etched better; the impurities and metal ions stripped from the quartz sand have a particle size much smaller than that of the quartz sand, and under the comprehensive action of electric charge, gravity and water flow, the impurities and metal ions pass through the filter hole of the reaction container, and the large particles gradually deposit at the bottom of the electrolytic cell, and the small metal cations are attracted and gathered near the cathode, so that the surface of the quartz sand is not easy to adsorb small particles.

[0030] Preferably, the device further comprises a circulating assembly, the circulating assembly comprising a circulating water pump, a water inlet pipe connected with the water inlet end of the circulating water pump, and a water outlet pipe connected with the water outlet end of the circulating water pump; a pressure nozzle is arranged at the lower part of the tungsten rod electrode, and the water outlet pipe of the circulating water pump is connected with the pressure nozzle.

[0031] By the technical scheme, with the discharge of the anode, the alkaline electrolyte in the alkaline electrolyte reacts with the impurities in the quartz sand, so that the concentration of the alkaline electrolyte near the anode is low, and by arranging the circulating assembly, the water inlet pipe is arranged near one end of the plate graphite electrode when the quartz sand is subjected to electrochemical purification, so that the electrolyte at the plate graphite electrode is pumped to the tungsten rod electrode by the circulating water pump, so that the alkaline electrolyte near the anode is maintained in a relatively constant concentration range during the discharge process. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0033] Figure 1 are scanning electron microscope images of high-purity quartz sand samples of Examples 1-6.

[0034] Figure 2 are scanning electron microscope images of quartz sand samples of Comparative Examples 1-2.

[0035] Figure 3 is a structural schematic diagram of Example 7.

[0036] In the figure, 1, electrolytic cell; 2, reaction container; 3, direct current pulse power supply; 4, plate graphite electrode; 5, alkaline electrolyte; 6, tungsten rod electrode; 7, circulating assembly; 71, circulating water pump; 72, water inlet pipe; 73, water outlet pipe; 74, nozzle joint; 8, pressure nozzle. DETAILED DESCRIPTION

[0037] In order to more clearly illustrate the present application, the following further describes the application in conjunction with the examples. Those skilled in the art should understand that the following description is a detailed description of the content of the application and is not a limitation, and therefore should not be used to limit the scope of protection of the present application.

[0038] EXAMPLE

[0039] Example 1

[0040] A method for manufacturing high-purity quartz sand by liquid-phase discharge method, comprising the following method steps:

[0041] Step S1, pretreatment, after magnetic separation, the quartz sand is placed into a mixed acid treatment liquid for 6 hours, and then washed with ultrapure water to obtain pretreated sand; the mixed acid treatment liquid comprises 3wt% HF, 8% HCl and 0.5wt% hydroxyethylidene diphosphonic acid.

[0042] Step S2, liquid-phase discharge purification, the pretreated sand is placed into an insulating material reaction container, a filter hole is provided on the reaction container, and the diameter of the filter hole is smaller than the diameter of the selected quartz sand; the reaction container is placed into an electrolytic cell containing an alkaline electrolyte, and the alkaline electrolyte is used to immerse the pretreated quartz sand in the reaction container; the alkaline electrolyte comprises 7wt% NaOH, 14wt% KOH and 2wt% sodium dodecyl sulfate.

[0043] A cathode connected to the negative pole of the power supply is inserted into the electrolytic cell, and an anode connected to the positive pole of the power supply is inserted into the reaction container. The power supply is turned on, a pulse direct current voltage of 15V is applied to the electrolytic cell, and the quartz sand in the reaction container is taken out after 30 minutes of treatment for standby.

[0044] Step S3, neutralization treatment, the quartz sand treated in step S2 is added into a combined acid neutralization liquid for 30 minutes of immersion washing, and then taken out and washed with ultrapure water; the combined acid neutralization liquid comprises 0.5wt% hydrochloric acid and 0.5wt% oxalic acid.

[0045] Step S4, dehydration, the quartz sand treated in step S3 is added with a silane coupling agent, and then centrifuged at a speed of 800-1200 rpm for dehydration.

[0046] Step S5, dehydroxylation, the quartz sand treated in step S4 is heated at 950℃ for 30 minutes to obtain the high-purity quartz sand.

[0047] Example 2

[0048] A method for manufacturing high-purity quartz sand by liquid-phase discharge method, comprising the following method steps:

[0049] Step S1, pretreatment, after magnetic separation of the quartz sand, the quartz sand is soaked in a mixed acid treatment liquid for 6 hours, and after being taken out, it is washed with ultrapure water to obtain pretreated sand; the mixed acid treatment liquid comprises 5wt% of HF, 2wt% of H2SO4, 14% of HCl and 1wt% of hydroxyethylidene diphosphonic acid.

[0050] Step S2, liquid-phase discharge purification, the pretreated sand is placed in a reaction container made of insulating material, a filter hole is provided on the reaction container, and the diameter of the filter hole is smaller than the diameter of the selected quartz sand; the reaction container is placed in an electrolytic cell containing an alkaline electrolyte, and the alkaline electrolyte is used to immerse the pretreated quartz sand in the reaction container; the alkaline electrolyte comprises 7wt% of NaOH, 14wt% of KOH and 2wt% of sodium dodecyl sulfate.

[0051] A cathode connected to the negative pole of the power supply is inserted into the electrolytic cell, and an anode connected to the positive pole of the power supply is inserted into the reaction container. The power supply is turned on, a pulse direct current voltage of 15V is applied to the electrolytic cell, and after 30 minutes of treatment, the quartz sand in the reaction container is taken out for standby.

[0052] Step S3, neutralization treatment, the quartz sand treated in step S2 is added to a combined acid neutralization liquid for immersion washing for 30 minutes, and then taken out and washed with ultrapure water; the combined acid neutralization liquid comprises 0.5wt% of hydrochloric acid and 0.5wt% of oxalic acid.

[0053] Step S4, dehydration, a silane coupling agent is added to the quartz sand treated in step S3, and then centrifugal dehydration is performed at a speed of 800-1200 revolutions per minute.

[0054] Step S5, dehydroxylation, the quartz sand treated in step S4 is heated at 950℃ for 30 minutes to obtain the high-purity quartz sand.

[0055] Example 3

[0056] A method for manufacturing high-purity quartz sand by liquid-phase discharge method, comprising the following method steps:

[0057] Step S1, pretreatment, after magnetic separation of the quartz sand, the quartz sand is soaked in a mixed acid treatment liquid for 6 hours, and after being taken out, it is washed with ultrapure water to obtain pretreated sand; the mixed acid treatment liquid comprises 5wt% of HF, 2wt% of H2SO4, 14% of HCl and 1wt% of hydroxyethylidene diphosphonic acid.

[0058] Step S2, liquid phase discharge purification, the pretreated sand is put into a reaction container made of insulating material, the reaction container is provided with filter holes, the diameter of the filter holes is smaller than the diameter of the selected quartz sand; the reaction container is put into an electrolytic cell containing alkaline electrolyte, so that the alkaline electrolyte immerses the pretreated quartz sand in the reaction container; the alkaline electrolyte includes 10wt% NaOH, 20wt% KOH and 5wt% sodium dodecyl sulfate.

[0059] A cathode connected to the negative pole of the power supply is inserted into the electrolytic cell, and an anode connected to the positive pole of the power supply is inserted into the reaction container. The power supply is turned on, a pulse direct current voltage of 15V is applied to the electrolytic cell, and the quartz sand in the reaction container is taken out after 30 minutes of treatment for standby.

[0060] Step S3, neutralization treatment, the quartz sand treated in step S2 is added to a combined acid neutralizing liquid for immersion washing for 30 minutes, and then taken out and washed with ultrapure water; the combined acid neutralizing liquid includes 0.5wt% hydrochloric acid and 0.5wt% oxalic acid.

[0061] Step S4, dehydration, the quartz sand treated in step S3 is added with a silane coupling agent, and then centrifuged for dehydration at a speed of 800-1200 revolutions per minute.

[0062] Step S5, dehydroxylation, the quartz sand treated in step S4 is heated at 950℃ for 30 minutes to obtain the high-purity quartz sand.

[0063] Example 4

[0064] A method for manufacturing high-purity quartz sand by a liquid phase discharge method, comprising the following method steps:

[0065] Step S1, pretreatment, the quartz sand after magnetic separation is put into a mixed acid treatment liquid for immersion for 6 hours, and then taken out and washed with ultrapure water to obtain pretreated sand; the mixed acid treatment liquid includes 3wt% HF, 8% HCl and 0.5wt% hydroxyethylidene diphosphonic acid.

[0066] Step S2, liquid phase discharge purification, the pretreated sand is put into a reaction container made of insulating material, the reaction container is provided with filter holes, the diameter of the filter holes is smaller than the diameter of the selected quartz sand; the reaction container is put into an electrolytic cell containing alkaline electrolyte, so that the alkaline electrolyte immerses the pretreated quartz sand in the reaction container; the alkaline electrolyte includes 10wt% NaOH, 20wt% KOH and 5wt% sodium dodecyl sulfate.

[0067] A cathode connected to the negative pole of the power supply is inserted into the electrolytic cell, and an anode connected to the positive pole of the power supply is inserted into the reaction container. The power supply is turned on, a pulse direct current voltage of 15V is applied to the electrolytic cell, and the quartz sand in the reaction container is taken out after 30 minutes of treatment for standby.

[0068] Step S3, neutralization treatment, the quartz sand treated in step S2 is added into a combined acid neutralization liquid for immersion washing for 30 minutes, then taken out and washed with ultrapure water; the combined acid neutralization liquid includes 0.5wt% hydrochloric acid and 0.5wt% oxalic acid.

[0069] Step S4, dehydration, a silane coupling agent is added into the quartz sand treated in step S3, then centrifugal dehydration is performed at a speed of 800-1200 revolutions per minute.

[0070] Step S5, dehydroxylation, the quartz sand treated in step S4 is heated at 950℃ for 30 minutes to obtain the high-purity quartz sand.

[0071] Example 5

[0072] A method for manufacturing high-purity quartz sand by liquid-phase discharge method, including the following method steps:

[0073] Step S1, pretreatment, after magnetic separation, the quartz sand is put into a mixed acid treatment liquid for immersion for 6 hours, then taken out and washed with ultrapure water to obtain pretreated sand; the mixed acid treatment liquid includes 3wt% HF, 8% HCl and 0.5wt% hydroxyethylidene diphosphonic acid.

[0074] Step S2, liquid-phase discharge purification, the pretreated sand is put into a reaction container made of insulating material, a filter hole is arranged on the reaction container, the diameter of the filter hole is smaller than the diameter of the quartz sand selected; the reaction container is put into an electrolytic cell containing an alkaline electrolyte, so that the alkaline electrolyte immerses the pretreated quartz sand in the reaction container; the alkaline electrolyte includes 7wt% NaOH, 14wt% KOH and 2wt% sodium dodecyl sulfate.

[0075] A cathode connected to the negative pole of a power supply is inserted into the electrolytic cell, and an anode connected to the positive pole of the power supply is inserted into the reaction container; a pulse direct current voltage of 15V is applied to the electrolytic cell, and the quartz sand in the reaction container is taken out after treatment for 120 minutes for standby.

[0076] Step S3, neutralization treatment, the quartz sand treated in step S2 is added into a combined acid neutralization liquid for immersion washing for 30 minutes, then taken out and washed with ultrapure water; the combined acid neutralization liquid includes 0.5wt% hydrochloric acid and 0.5wt% oxalic acid.

[0077] Step S4, dehydration, a silane coupling agent is added into the quartz sand treated in step S3, then centrifugal dehydration is performed at a speed of 800-1200 revolutions per minute.

[0078] Step S5, dehydroxylation, the quartz sand treated in step S4 is heated at 950℃ for 30 minutes to obtain the high-purity quartz sand.

[0079] Example 6

[0080] A method for manufacturing high-purity quartz sand by liquid-phase discharge method, comprising the following method steps:

[0081] Step S1, pretreatment, after magnetic separation of quartz sand, the quartz sand is soaked in a mixed acid treatment liquid for 6 hours, and after being taken out, it is washed with ultrapure water to obtain pretreated sand; the mixed acid treatment liquid comprises 3wt% of HF, 8% of HCl and 0.5wt% of hydroxyethylidene diphosphonic acid.

[0082] Step S2, liquid-phase discharge purification, the pretreated sand is placed in a reaction container made of insulating material, a filter hole is provided on the reaction container, and the diameter of the filter hole is smaller than the diameter of the selected quartz sand; the reaction container is placed in an electrolytic cell containing an alkaline electrolyte, and the alkaline electrolyte is used to immerse the pretreated quartz sand in the reaction container; the alkaline electrolyte comprises 7wt% of NaOH, 14wt% of KOH and 2wt% of sodium dodecyl sulfate.

[0083] A cathode connected to the negative pole of the power supply is inserted into the electrolytic cell, and an anode connected to the positive pole of the power supply is inserted into the reaction container. The power supply is turned on, a pulse direct current voltage of 15V is applied to the electrolytic cell, and the quartz sand in the reaction container is taken out after 120 minutes of treatment for standby.

[0084] Step S3, neutralization treatment, the quartz sand treated in step S2 is added to a combined acid neutralization liquid and soaked for 30 minutes, then taken out and washed with ultrapure water; the combined acid neutralization liquid comprises 0.5wt% of hydrochloric acid and 0.5wt% of oxalic acid.

[0085] Step S4, dehydration, a silane coupling agent is added to the quartz sand treated in step S3, and then centrifugal dehydration is carried out at a speed of 800-1200 revolutions per minute.

[0086] Step S5, dehydroxylation, the quartz sand treated in step S4 is heated at 1050℃ for 30 minutes to obtain the high-purity quartz sand.

[0087] Example 7

[0088] A device for manufacturing high-purity quartz sand by liquid-phase discharge method, hereinafter referred to as purification device, with reference to Figure 3 , comprising an electrolytic cell 1, a reaction container 2, a direct current pulse power supply 3 and a circulating assembly 7. The electrolytic cell 1 is filled with an alkaline electrolyte 5; a plate graphite electrode 4 is provided at one end inside the electrolytic cell 1, and the plate graphite electrode 4 is connected to the negative pole of the direct current pulse power supply 3.

[0089] The reaction container 2 is made of inert material which is not easy to react with the alkaline electrolyte 5, and is provided with a filter hole. The reaction container 2 is internally provided with a tungsten rod electrode 6, and the lower part of the reaction container 2 is provided with a pressure spray head 8.

[0090] The electrolytic cell 1 is provided with a spray head joint 74 at the bottom of the end away from the plate graphite electrode 4, which is used to communicate and dock with the pressure spray head 8. The circulating assembly 7 includes a circulating water pump 71, a water inlet pipe 72 connected to the water inlet end of the circulating water pump 71, and a water outlet pipe 73 connected to the water outlet end of the circulating water pump 71; the water outlet pipe 73 is connected to the spray head joint 74.

[0091] When the purification device is used for liquid phase discharge purification of quartz sand, the quartz sand is placed in the reaction container 2, and then the reaction container 2 is placed in the electrolytic cell 1, so that the spray head joint 74 is docked with the pressure spray head 8 at the bottom of the reaction container 2. The alkaline electrolyte 5 in the electrolytic cell 1 should be able to immerse the quartz sand in the reaction container 2. The tungsten rod electrode 6 is connected to the positive electrode of the direct current pulse power supply 3, the direct current pulse power supply 3 is turned on, and the circulating water pump 71 is started.

[0092] Comparative Example

[0093] Comparative Example 1

[0094] A method for preparing high-purity quartz, comprising the following steps:

[0095] Alkaline leaching: the sieved quartz ore is mixed with sodium hydroxide solution for hot leaching, and the alkaline leaching conditions are that the concentration of the alkaline solution is 0.06 mol / L, the addition speed is 5 ml(g·min) -1 , the temperature is 300℃, and the leaching time is 4 hours;

[0096] Acid leaching: the quartz after alkaline leaching is mixed with hydrochloric acid solution for hot leaching, and the acid leaching conditions are that the concentration of the acid solution is 0.06 mol / L, the addition speed is 5 ml(g·min) -1 , the temperature is 300℃, the leaching time is 4 hours, and then water washing, filtration and drying are performed to obtain high-purity quartz.

[0097] The above method process is taken from the patent application file with the application publication number CN112919478A and the name of a high-purity quartz sand purification method and device.

[0098] Comparative Example 2

[0099] A method for purifying high-purity quartz sand, comprising the following steps:

[0100] (1) Quartz sand raw material: The vein quartz raw ore is pretreated by crushing, calcining, water quenching, and grinding, to obtain a quartz sand raw material with a particle size of 100 mesh. The quartz sand raw material is subjected to microwave heating, with a heating power of 2000W and a heating time of 1h.

[0101] (2) Mixed acid leaching: The quartz sand is soaked in a chemical solution. The chemical solution is a mixed solution of sulfuric acid with a concentration of 20%, hydrochloric acid with a concentration of 20%, and hydrofluoric acid with a concentration of 10%. The acid leaching temperature is 80℃, and the acid leaching time is 4h.

[0102] (3) Silica colloid purification: The quartz sand is soaked in a silica colloid. The silica colloid used is ultra-high purity silica colloid with a purity of 99.9999% and a mass concentration of 20%. The silica colloid is first subjected to an alternating electric field (10V / 20kHz) for 5min to fully contact with the quartz sand, then it is left to stand for 30min, and finally it is subjected to a direct current electric field (100V) to separate from the quartz sand.

[0103] (4) The quartz sand is washed and dried.

[0104] The above method process is taken from the patent document with the authorized publication number CN 114477188 B and the name of a high-purity quartz sand purification method and device.

[0105] Test method

[0106] The quartz sand samples prepared in Examples 1-6 and the quartz sand samples prepared in Comparative Examples 1-2 are tested according to the following method.

[0107] 1. The quartz sand samples are detected for impurity elements according to the method in JY / T 0567-2020, and the detection results are shown in Table 1.

[0108] 2. The quartz sand samples of Examples 1-6 and Comparative Examples 1-2 are observed under an electronic display microscope. The model of the electronic microscope is JSM-IT510, with a magnification of 500 times.

[0109] Figure 1 In the figure, the numbers 1-6 correspond to the electron microscope images of the quartz sand samples of Examples 1-6, respectively.

[0110] Figure 2 In the figure, the numbers 7-8 correspond to the electron microscope images of the quartz sand samples of Comparative Examples 1-2, respectively.

[0111]

[0112] Table 1 Detection results of impurity content of quartz sand samples

[0113] From Table 1, it can be seen that the removal of Al, Li and Ti in Examples 1-6 is obviously better than that in Comparative Examples 1-2, and the overall impurity content is also better than that in Comparative Examples 1 and 2.

[0114] From the results of the examples, it can be seen that appropriately increasing the concentration of the mixed acid treatment solution and the alkaline electrolyte or increasing the dehydroxylation heating temperature can promote the removal of impurities; simply increasing the pulse power voltage or prolonging the liquid phase discharge reaction time cannot significantly improve the impurity removal effect, and instead, excessive removal can affect the overall removal effect.

[0115] From the SEM photos of Table 1 and Figure 1 , Figure 2 It can be seen from the SEM photos of Table 1 and

[0116] Although some specific embodiments of the application have been described in detail above, those skilled in the art should understand that the above examples are only for illustration, and are not intended to limit the scope of the application. Those skilled in the art should understand that the above examples can be modified without departing from the scope and spirit of the application. The scope of the application is defined by the appended claims.

Claims

1. A method of manufacturing high purity quartz sand by liquid phase discharge method, characterized by, The method comprises the following steps: Step S1, pretreatment, the quartz sand is put into a mixed acid treatment solution after magnetic separation for 6-8 hours, and then washed with ultrapure water to obtain pretreated sand; the mixed acid treatment solution comprises 3-5wt% of HF, 0-2wt% of H2SO4, 8-14wt% of HCl and 0.5-1wt% of hydroxyethylidene diphosphonic acid; Step S2, liquid phase discharge purification, the pretreated sand is put into an insulating material reaction container, a filter hole is arranged on the reaction container, the diameter of the filter hole is smaller than the diameter of the selected quartz sand, the reaction container is put into an electrolytic cell containing an alkaline electrolyte, the alkaline electrolyte is used to immerse the pretreated quartz sand in the reaction container, a cathode connected to the negative pole of a power supply is inserted into the electrolytic cell, and an anode connected to the positive pole of the power supply is inserted into the reaction container, the power supply is turned on, a pulse direct current voltage of 15-45V is applied to the electrolytic cell, the quartz sand in the reaction container is taken out after 30-120 minutes of treatment, and the quartz sand is reserved; the alkaline electrolyte comprises 7-10wt% of NaOH, 14-20wt% of KOH and 2-5wt% of sodium dodecyl sulfate; Step S3, neutralization treatment, the quartz sand treated in step S2 is added into a combined acid neutralization solution for 30-60 minutes of immersion and washing, and then taken out and washed with ultrapure water; the combined acid neutralization solution comprises 0.5-1wt% of hydrochloric acid and 0.5-1wt% of oxalic acid; Step S4, dehydration, a coupling agent is added into the quartz sand treated in step S3 and mixed uniformly, and then centrifugal dehydration is performed to remove the water contained in the quartz sand; Step S5, dehydroxylation, the quartz sand treated in step S4 is heated at 950-1050℃ for 30-50 minutes to obtain the high-purity quartz sand.

2. The method for manufacturing high purity quartz sand by liquid phase discharge method according to claim 1, characterized by: In step S2, a pressure spray head is arranged at the lower part of the anode, the quartz sand near the discharge end of the anode is impacted by the pressure spray head to make the quartz sand flow and roll.

3. The method for manufacturing high purity quartz sand by liquid phase discharge method according to claim 2, characterized in that: The pressure spray head is connected with a circulating water pump, and the alkaline electrolyte at the cathode is pumped to the vicinity of the anode by the circulating water pump.

4. The method for manufacturing high purity quartz sand by liquid phase discharge method according to claim 1, characterized in that: The coupling agent is a silane coupling agent.

5. The method for manufacturing high purity quartz sand by liquid phase discharge method according to claim 1, characterized in that: The cathode is a plate graphite electrode, and the anode is a tungsten rod electrode with a tapered end.

6. The method of claim 1, wherein the method is characterized by: The following device is adopted, which comprises an electrolytic cell, a reaction container and a direct current pulse power supply, the electrolytic cell contains an alkaline electrolyte; the reaction container is provided with a filter hole, one end of the electrolytic cell is provided with a plate graphite electrode, the plate graphite electrode is connected with the negative pole of the direct current pulse power supply, the reaction container is provided with a tungsten rod electrode, and the tungsten rod electrode is connected with the positive pole of the direct current pulse power supply.

7. The method of claim 6, wherein the method is characterized by: A circulating assembly is further included, which comprises a circulating water pump, a water inlet pipe connected with the water inlet end of the circulating water pump and a water outlet pipe connected with the water outlet end of the circulating water pump; the lower part of the tungsten rod electrode is provided with a pressure spray head, and the water outlet pipe of the circulating water pump is connected with the pressure spray head.

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