Quartz sand purification waste acid recovery method

Abstract

The invention discloses a quartz sand purification waste acid recovery method. The method specifically comprises the following steps: step 1, filtering; step 2, molecular migration; step 3, gas-liquid separation; step 4, electrolysis; step 5, laser synthesis; the invention relates to the technical field of fluosilicic acid purification treatment. According to the quartz sand purification waste acid recovery method, quartz sand purification waste acid is recovered through a membrane separation technology, the operation is simple, the cost is low, the efficiency is high, gas-liquid separation treatment on waste acid and electrolysis on reuse water are combined with the arrangement of a laser synthesis furnace, and the recovery efficiency of the waste acid is improved. High-purity hydrogen fluoride gas and quartz sand products can be obtained, the product quality is improved, waste acid discharge can be reduced, environmental pollution is reduced, green and environment-friendly support is provided for improvement of industrial production efficiency, dilute acid is heated, the purpose of no sewage discharge in the waste acid recovery process is achieved, resource waste is avoided, and meanwhile the production cost is reduced. And the production cost is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of fluosilicic acid purification and treatment, in particular to a method for recovering waste acid from quartz sand purification. Background Art

[0002] At present, in the industries of new energy such as photovoltaics and energy storage as well as new materials such as electronic-grade ultra-pure quartz powder, the annual consumption of hydrogen fluoride in the quartz purification process is ≥200,000 tons, the annual consumption of hydrogen fluoride in the glass etching process is ≥500,000 tons, the annual consumption of hydrogen fluoride in the glass thinning process is ≥300,000 tons, and the annual consumption of hydrogen fluoride in the silicon negative electrode preparation process is ≥100,000 tons. It can be seen that a large amount of hydrofluoric acid is used in these processes, and a large amount of dilute fluorosilicic acid with a concentration of 0.1%-10% is produced.

[0003] In the prior art, a large amount of dilute fluorosilicic acid cannot be recycled. That is, the treatment method for dilute fluorosilicic acid is often to directly use slaked lime for acid-base neutralization and adjust the pH value of the sewage. This not only causes production companies to spend huge costs on wastewater discharge, but also produces a large amount of low-grade calcium fluorosilicate, resulting in waste of resources and high production costs.

[0004] Based on the search of the above information, a method for recovering waste acid from quartz sand purification is proposed to achieve effective recovery and utilization of dilute fluorosilicic acid. While saving energy and protecting the environment, high-purity synthetic quartz, high-purity silicon dioxide powder and hydrogen fluoride are extracted to avoid waste of resources. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for recovering waste acid from quartz sand purification, which solves the problem that the existing dilute fluorosilicic acid cannot be effectively recycled, resulting in waste of resources and high processing costs.

[0006] To achieve the above purpose, the present invention is implemented by the following technical scheme: a method for recovering waste acid from quartz sand purification, specifically comprising the following steps: Step 1, filtration: solid-liquid separation of waste acid generated during the purification of quartz sand; Step 2, molecular migration: introducing the waste acid obtained after solid-liquid separation into a molecular migration device to obtain recycled water and fluorinated silicic acid liquid; Step 3: Gas-liquid separation: perform gas-liquid separation on the fluorinated silicic acid liquid to obtain dilute acid and gas; Step 4: electrolysis: introducing the recycled water obtained in step 2 into an electrolytic cell to obtain hydrogen and oxygen; Step 5: Laser synthesis: Introduce the gas in step 3 and the hydrogen and oxygen in step 4 into a laser synthesis furnace to obtain hydrogen fluoride gas and quartz sand products.

[0007] The present invention is further configured as follows: the molecular migration device in step 2 is a membrane separation device, and the membrane separation device is a reverse osmosis membrane.

[0008] The present invention is further configured such that: the conductivity of the recycled water in step 2 is less than 50 US.

[0009] The present invention is further configured as follows: the concentration of fluorosilicic acid in the waste acid in step one is 0.01%-20%, and the concentration of fluorosilicic acid in the fluorosilicic acid-containing liquid in step two is 30%-40%.

[0010] The present invention is further configured as follows: the gas-liquid separation in step 3 is performed by heating and boiling to separate the dilute acid and the gas, wherein the boiling temperature is 108.5°C; The gas includes silicon tetrafluoride and hydrogen fluoride gas; The dilute acid is silicic acid, and its reaction chemical formula in step 3 is: SiF4+3H2O=H2SiO3+4HF↑.

[0011] The present invention is further configured as follows: the process for obtaining the dilute acid in step 3 comprises: The diluted acid is introduced into a heating furnace and heated at 150° C. to obtain silicon dioxide and water, wherein the water is condensed and introduced into the recycled water in step 2; The reaction chemical formula in the heating furnace is: H2SiO3=SiO2+H2O.

[0012] The present invention is further configured as follows: the quartz sand product in step five includes silicon dioxide powder, quartz rods and quartz lumps.

[0013] The present invention is further configured as follows: the reaction chemical formula in the laser synthesis furnace in step 5 is: SiF4+2H2+O2=SiO2+4HF↑. Beneficial Effects

[0014] The present invention provides a method for recovering waste acid from quartz sand purification, which has the following beneficial effects: (1) The present invention utilizes membrane separation technology to purify waste acid from quartz sand for recycling, which is simple to operate and has the advantages of low cost and high efficiency. In addition, through gas-liquid separation of waste acid and electrolysis of recycled water, combined with the setting of a laser synthesis furnace, high-purity hydrogen fluoride gas and quartz sand products can be obtained, thereby improving product quality, reducing waste acid emissions, and reducing environmental pollution, providing green and environmentally friendly support for improving industrial production efficiency.

[0015] (2) The present invention heats the dilute acid obtained in the gas-liquid separation to prepare silicon dioxide and water, thereby achieving the purpose of no wastewater discharge during the waste acid recovery process and realizing the efficient recovery and reuse of the waste acid purified by quartz sand, thereby avoiding the waste of resources and effectively reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1 , the embodiment of the present invention provides the following three technical solutions: Embodiment 1

[0019] A method for recovering waste acid from quartz sand purification, comprising the following steps: Step 1, filtration: the waste acid generated during the purification of quartz sand is subjected to solid-liquid separation, wherein the concentration of fluorosilicic acid in the waste acid obtained after solid-liquid separation is 0.01%; Step 2, molecular migration: the waste acid obtained after solid-liquid separation is introduced into a molecular migration device to obtain recycled water and fluorinated silicic acid liquid, wherein the molecular migration device is a membrane separation device, the membrane separation device uses a reverse osmosis membrane, and the conductivity of the recycled water is less than 50US; The concentration of fluorosilicic acid in the fluorosilicic acid-containing liquid is 30%; Step 3, gas-liquid separation: perform gas-liquid separation on the fluorinated silicic acid liquid to obtain dilute acid and gas, wherein the gas-liquid separation is performed by heating and boiling, wherein the boiling temperature is 108.5°C; The gas includes silicon tetrafluoride and hydrogen fluoride gas; The dilute acid is silicic acid, and its reaction chemical formula in step 3 is: SiF4+3H2O=H2SiO3+4HF↑; In order to achieve zero discharge of wastewater, the treatment process for obtaining dilute acid in step 3 includes: The diluted acid is introduced into a heating furnace and heated at 150° C. to obtain silicon dioxide and water, wherein the water is condensed and introduced into the recycled water in step 2; The reaction chemical formula in the heating furnace is: H2SiO3=SiO2+H2O; Step 4: electrolysis: introducing the recycled water obtained in step 2 into an electrolytic cell to obtain hydrogen and oxygen; Step 5, laser synthesis: introducing the gas in step 3 and the hydrogen and oxygen in step 4 into a laser synthesis furnace to obtain hydrogen fluoride gas and quartz sand products, wherein the quartz sand products include silicon dioxide powder, quartz rods and quartz lumps; The reaction chemical formula in the laser synthesis furnace is: SiF4+2H2+O2=SiO2+4HF↑. Embodiment 2

[0020] A method for recovering waste acid from quartz sand purification, comprising the following steps: Step 1, filtration: the waste acid generated during the purification of quartz sand is subjected to solid-liquid separation, wherein the concentration of fluorosilicic acid in the waste acid obtained after solid-liquid separation is 20%; Step 2, molecular migration: the waste acid obtained after solid-liquid separation is introduced into a molecular migration device to obtain recycled water and fluorinated silicic acid liquid, wherein the molecular migration device is a membrane separation device, the membrane separation device uses a reverse osmosis membrane, and the conductivity of the recycled water is less than 50US; The concentration of fluorosilicic acid in the fluorosilicic acid-containing liquid is 40%; Step 3, gas-liquid separation: perform gas-liquid separation on the fluorinated silicic acid liquid to obtain dilute acid and gas, wherein the gas-liquid separation is performed by heating and boiling, wherein the boiling temperature is 108.5°C; The gas includes silicon tetrafluoride and hydrogen fluoride gas; The dilute acid is silicic acid, and its reaction chemical formula in step 3 is: SiF4+3H2O=H2SiO3+4HF↑; In order to achieve zero discharge of wastewater, the treatment process for obtaining dilute acid in step 3 includes: The diluted acid is introduced into a heating furnace and heated at 150° C. to obtain silicon dioxide and water, wherein the water is condensed and introduced into the recycled water in step 2; The reaction chemical formula in the heating furnace is: H2SiO3=SiO2+H2O; Step 4: electrolysis: introducing the recycled water obtained in step 2 into an electrolytic cell to obtain hydrogen and oxygen; Step 5, laser synthesis: introducing the gas in step 3 and the hydrogen and oxygen in step 4 into a laser synthesis furnace to obtain hydrogen fluoride gas and quartz sand products, wherein the quartz sand products include silicon dioxide powder, quartz rods and quartz lumps; The reaction chemical formula in the laser synthesis furnace is: SiF4+2H2+O2=SiO2+4HF↑. Embodiment 3

[0021] A method for recovering waste acid from quartz sand purification, comprising the following steps: Step 1, filtration: the waste acid generated during the purification of quartz sand is subjected to solid-liquid separation, wherein the concentration of fluorosilicic acid in the waste acid obtained after solid-liquid separation is 5%; Step 2, molecular migration: the waste acid obtained after solid-liquid separation is introduced into a molecular migration device to obtain recycled water and fluorinated silicic acid liquid, wherein the molecular migration device is a membrane separation device, the membrane separation device uses a reverse osmosis membrane, and the conductivity of the recycled water is less than 50US; The concentration of fluorosilicic acid in the fluorosilicic acid-containing liquid is 33%; Step 3, gas-liquid separation: perform gas-liquid separation on the fluorinated silicic acid liquid to obtain dilute acid and gas, wherein the gas-liquid separation is performed by heating and boiling, wherein the boiling temperature is 108.5°C; The gas includes silicon tetrafluoride and hydrogen fluoride gas; The dilute acid is silicic acid, and its reaction chemical formula in step 3 is: SiF4+3H2O=H2SiO3+4HF↑; In order to achieve zero discharge of wastewater, the treatment process for obtaining dilute acid in step 3 includes: The diluted acid is introduced into a heating furnace and heated at 150° C. to obtain silicon dioxide and water, wherein the water is condensed and introduced into the recycled water in step 2; The reaction chemical formula in the heating furnace is: H2SiO3=SiO2+H2O; Step 4: electrolysis: introducing the recycled water obtained in step 2 into an electrolytic cell to obtain hydrogen and oxygen; Step 5, laser synthesis: introducing the gas in step 3 and the hydrogen and oxygen in step 4 into a laser synthesis furnace to obtain hydrogen fluoride gas and quartz sand products, wherein the quartz sand products include silicon dioxide powder, quartz rods and quartz lumps; The reaction chemical formula in the laser synthesis furnace is: SiF4+2H2+O2=SiO2+4HF↑.

[0022] In summary, it can be seen that according to the above embodiment, the membrane separation technology is used to purify the waste acid from quartz sand for recovery, which is simple to operate and has the advantages of low cost and high efficiency. In addition, through the gas-liquid separation treatment of the waste acid and the electrolysis of the recycled water, combined with the setting of the laser synthesis furnace, high-purity hydrogen fluoride gas and quartz sand products can be obtained, the product quality can be improved, the waste acid discharge can be reduced, and the environmental pollution can be reduced, providing green and environmental protection support for the improvement of industrial production efficiency. In addition, by heating the dilute acid obtained in the gas-liquid separation and preparing silicon dioxide and water, the purpose of no sewage discharge in the waste acid recovery process is achieved, and the efficient recovery and reuse of the waste acid from quartz sand purification is realized, which avoids the waste of resources and effectively reduces the production cost.

[0023] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions. The sentence "includes an element defined by... does not exclude the existence of other identical elements in the process, method, article or device including the element".

[0024] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for recovering waste acid from quartz sand purification, characterized in that: The specific steps include: Step 1, filtration: solid-liquid separation of waste acid generated during the purification of quartz sand; Step 2, molecular migration: introducing the waste acid obtained after solid-liquid separation into a molecular migration device to obtain recycled water and fluorinated silicic acid liquid; Step 3: Gas-liquid separation: perform gas-liquid separation on the fluorinated silicic acid liquid to obtain dilute acid and gas; Step 4: electrolysis: introducing the recycled water obtained in step 2 into an electrolytic cell to obtain hydrogen and oxygen; Step 5: Laser synthesis: Introduce the gas in step 3 and the hydrogen and oxygen in step 4 into a laser synthesis furnace to obtain hydrogen fluoride gas and quartz sand products.

2. A method for recovering waste acid from quartz sand purification according to claim 1, characterized in that: The molecular migration device in the step 2 is a membrane separation device, and the membrane separation device uses a reverse osmosis membrane.

3. A method for recovering waste acid from quartz sand purification according to claim 1, characterized in that: The conductivity of the recycled water in step 2 is less than 50 US.

4. A method for recovering waste acid from quartz sand purification according to claim 1, characterized in that: The concentration of fluorosilicic acid in the waste acid in step 1 is 0.01%-20%, and the concentration of fluorosilicic acid in the fluorosilicic acid-containing liquid in step 2 is 30%-40%.

5. A method for recovering waste acid from quartz sand purification according to claim 1, characterized in that: The gas-liquid separation in step 3 is carried out by heating and boiling to separate the dilute acid and the gas, wherein the boiling temperature is 108.5°C; The gas includes silicon tetrafluoride and hydrogen fluoride gas; The dilute acid is silicic acid, and its reaction chemical formula in step 3 is: SiF4+3H2O=H2SiO3+4HF↑.

6. A method for recovering waste acid from quartz sand purification according to claim 5, characterized in that: The process for obtaining dilute acid in step 3 includes: The diluted acid is introduced into a heating furnace and heated at 150° C. to obtain silicon dioxide and water, wherein the water is condensed and introduced into the recycled water in step 2; The reaction chemical formula in the heating furnace is: H2SiO3=SiO2+H2O.

7. A method for recovering waste acid from quartz sand purification according to claim 1, characterized in that: The quartz sand product in step five includes silicon dioxide powder, quartz rods and quartz lumps.

8. A method for recovering waste acid from quartz sand purification according to claim 1, characterized in that: The reaction chemical formula in the laser synthesis furnace in step 5 is: SiF4+2H2+O2=SiO2+4HF↑.

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