High-purity quartz sand purification process

Abstract

The invention discloses a high-purity quartz sand purification process, relates to the technical field of quartz sand processing, and aims to solve the problems of waste acid pollution, excessive use of acid, wastewater treatment, water resource consumption, equipment corrosion and the like, realize recycling of waste acid and wastewater, reduce cost and reduce environmental pollution. The method comprises the following steps: S1, acid purification: adding a quartz sand raw material into a reaction kettle, adding reaction acid into the reaction kettle according to a certain solid-to-liquid ratio, heating the reaction kettle, reacting for a period of time, and cooling to dissolve impurities in quartz; s2, filter pressing and cleaning: feeding the pickled material to a plate frame for filter pressing to form a filter cake, cleaning the filter cake with clear water for 1-4 times, feeding the filter cake to the plate frame for filter pressing again, separately collecting waste acid, recycling waste water to a waste water pool, and recycling the waste water after purification; s3, repeating acid purification and filter-pressing cleaning for several times until various acids are used up in the process; and S4, drying: putting the cleaned filter cake into a drying system for drying to obtain the high-purity quartz sand with the purity being greater than or equal to 99.9%.

Description

Technical Field

[0001] The invention relates to the technical field of quartz sand processing, in particular to a high-purity quartz sand purification process. Background Art

[0002] In modern industrial production, high-purity quartz sand is widely used in glass, casting, ceramics, fireproof materials, metallurgy, chemical industry and other fields due to its excellent physical and chemical properties. With the rapid development of science and technology, the purity requirements for high-purity quartz sand are also increasing, making it a valuable component of green environmental protection strategic resources. However, the traditional high-purity quartz sand production process, including the steps of coarse crushing, fine crushing, grinding, particle size sorting, flotation, magnetic separation, acid leaching, high-temperature chlorination roasting and high-temperature calcination of the raw ore, has significant environmental and cost problems. In particular, in the acid leaching step, the use of mixed acids such as hydrochloric acid, nitric acid and hydrofluoric acid to remove impurities can effectively reduce the iron content in quartz sand and improve the purity, but it also brings the problem of waste acid and wastewater treatment. If these waste acids and wastewater are not properly treated, they will directly cause environmental pollution and waste of resources, while increasing production costs and bringing safety risks.

[0003] In addition, the mixed nature of waste acid in the existing process increases the difficulty of recycling and treatment, and the high-temperature chlorination roasting process is not only energy-intensive and corrosive, but also may have the risk of uncontrolled release of toxic gases. Therefore, it has become an urgent need for the development of the industry to develop a new high-purity quartz sand production process to achieve effective recycling of waste acid and wastewater, reduce environmental pollution and resource waste, reduce energy consumption and production costs, and ensure the safety of the production process. Summary of the invention

[0004] In order to solve the above problems, that is, to solve the problems raised by the above background technology, the present invention proposes a high-purity quartz sand purification process, which includes the following steps: S1, acid purification: adding quartz sand raw materials into a reactor, adding reaction acid into the reactor according to a certain solid-liquid ratio, heating the reactor for a period of time and then cooling it down to dissolve impurities in the quartz; S2, filter pressing and cleaning: sending the acid-washed material to a plate-frame filter press to form a filter cake, washing the filter cake with clean water for 1 to 4 times, sending the filter cake to the plate-frame filter press again, and collecting the waste acid separately, The waste water is recycled to the waste water pool and reused after purification; S3, repeat acid purification and filter pressing cleaning several times until all acids in the process are used up; S4, drying: the cleaned filter cake is put into the drying system for drying to obtain high-purity quartz sand with a purity of ≥99.9%; S5, waste acid purification: the generated waste acid is collected separately, and each waste acid is purified by evaporation and condensation for later use; S6, wastewater purification: the generated waste water is recycled to the waste water pool, and the waste water is purified and set aside in the manner of industrial wastewater treatment.

[0005] The present invention is further configured as follows: in S1, the reaction acids are hydrochloric acid, hydrofluoric acid, nitric acid, hydrochloric acid, and nitric acid in the order of only one each time for acid purification.

[0006] The present invention is further configured as follows: the hydrochloric acid concentration range is 3-6 mol / L, and the reaction time range is 20-60 min.

[0007] The present invention is further configured as follows: the hydrofluoric acid concentration ranges from 0.5 to 2 mol / L, and the reaction time ranges from 20 to 50 min.

[0008] The present invention is further configured as follows: the nitric acid concentration ranges from 1 to 3 mol / L, and the reaction time ranges from 20 to 60 min.

[0009] The present invention is further configured as follows: in S1 and S3, the solid-liquid ratio of the first acid purification and acid addition is in the range of 1:7-10, the solid-liquid ratio of the repeated acid purification and acid addition is in the range of 1:8-12, and the reaction temperature in the reactor is in the range of 50-90°C.

[0010] The present invention is further configured as follows: in S2, the amount of clean water used for each cleaning is the same as the amount of the corresponding reaction acid used.

[0011] The present invention is further configured as follows: in S4, the drying temperature range in the drying system is 150-200°C.

[0012] The present invention is further configured as follows: in said S5, the waste acid purification comprises the following steps: S501, purifying different types of previous waste acids separately, adding sulfuric acid in a concentration range of 20-80% to the evaporator; S502, adding the waste acid to the evaporator, evaporating the mixed acid of sulfuric acid and waste acid, controlling the vacuum degree and temperature of the evaporator, the vacuum degree range is -760mm~-680mm mercury column, the temperature range is 70~100°C, and the evaporated gas is recovered by condensation to obtain recovered acid; S503, after testing the recovered acid, preparing it according to the concentration required for acid purification as the corresponding type of reaction acid.

[0013] The present invention is further configured as follows: in said S6, the wastewater purification comprises the following steps: S601, adjusting the pH value: adding one or more of calcium hydroxide, sodium hydroxide or sodium carbonate in a concentration range of 2-4%, 3-5% or 3-5% to the wastewater, neutralizing the acid in the wastewater, and adjusting the pH value to 9-11; S602, flocculation precipitation: adding a certain amount of one or more of flocculants PAC or PAM to the neutralized wastewater, the amount of PAC added is in the range of 2-5 mg / L, and the amount of PAM added is in the range of 0.1-0.5 mg / L, and after precipitation in a sedimentation tank, removing part of the precipitate and suspended matter; S603, multi-stage filtration and impurity removal: filtering the precipitated wastewater through quartz sand and ultrafiltration in turn, removing calcium ions, fluoride ions and heavy metals through ion exchange resin, and then undergoing two-stage reverse osmosis, and finally EDI purification and desalination, so that the wastewater reaches the ultrapure water standard.

[0014] The beneficial technical effects of the present invention are as follows: the present invention significantly improves the purity of quartz sand through acid leaching and purification technology, realizes efficient recycling of waste acid and waste water, and effectively reduces environmental pollution and resource consumption. By optimizing the pickling process, the closed-loop circulation of waste acid is realized, the use of new acid is reduced, the cost is reduced, and the risk of acid pollution is reduced. At the same time, the waste water is recycled and reused after purification, reducing water resource consumption. The reaction devices used in this process are all made of special materials to resist acid corrosion and extend the service life of the equipment. In addition, the process avoids the high-temperature roasting process, reduces energy consumption and toxic and harmful gas emissions, and realizes green production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The process flow chart of the present invention is shown.

[0016] Figure 2 A schematic diagram of the first inspection result is shown.

[0017] Figure 3 A schematic diagram of the second inspection result is shown. DETAILED DESCRIPTION

[0018] Please refer to the attached Figures 1 to 3 Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention. Example

[0019] S1. Acid purification: 500g of -100 mesh quartz sand raw material is added to a reactor, which is made of steel-lined PTFE material. Then 4200ml of reactive hydrochloric acid is added to the reactor, and the concentration of hydrochloric acid is 4.66mol / L. The temperature in the reactor is controlled at 85°C, and the reaction time is reduced to 30°C after 30min.

[0020] S2. Filter pressing and cleaning: the acid-washed material is sent to the plate and frame filter pressing to form a filter cake, and the waste acid is collected separately; the filter cake is washed with clean water for 3 times, and the amount of clean water added each time is 4200 ml, and the waste water is collected; then the filter cake is sent to the plate and frame filter pressing again, and the waste water is collected.

[0021] S3, repeat the acid purification and filter press cleaning 4 times until all acids in the process are used up; The filter cake enters the reactor for the second time, and 4000ml of hydrofluoric acid is added. The concentration of hydrofluoric acid is 1.57mol / L. The temperature in the reactor is controlled at 85℃. After 30min of reaction time, the temperature is lowered to 30℃, and then it enters the plate and frame filter press, and the waste acid is collected separately; the filter cake is washed with clean water 3 times, and the amount of clean water added each time is 4000ml, and the waste water is collected; then the filter cake is sent to the plate and frame filter press again, and the waste water is collected.

[0022] The filter cake enters the reactor for the third time, and 3000ml of nitric acid is added. The concentration of nitric acid is 1.03mol / L. The temperature in the reactor is controlled at 85℃. After 30min of reaction time, the temperature is lowered to 30℃, and then it enters the plate and frame filter press, and the waste acid is collected separately; the filter cake is washed with clean water 3 times, and the amount of clean water added each time is 3000ml, and the waste water is collected; then the filter cake is sent to the plate and frame filter press again, and the waste water is collected.

[0023] The filter cake entered the reactor for the fourth time, and 4200ml of reaction hydrochloric acid was added. The concentration of hydrochloric acid was 4.66mol / L. The temperature in the reactor was controlled at 85℃. After 30min of reaction time, the temperature was lowered to 30℃, and then entered the plate and frame filter press. The waste acid was collected separately. The filter cake was washed with clean water 3 times, and the amount of clean water added each time was 4200ml. The waste water was collected. Then the filter cake was sent to the plate and frame filter press again, and the waste water was collected.

[0024] The filter cake enters the reactor for the fifth time, and 3000 ml of nitric acid is added. The concentration of nitric acid is 1.03 mol / L. The temperature in the reactor is controlled at 85°C. After 30 minutes of reaction, the temperature is lowered to 30°C, and then it enters the plate and frame filter press. The waste acid is collected separately. The filter cake is washed with clean water 3 times, and the amount of clean water added each time is 3000 ml. After the waste water is collected, the filter cake enters the next process.

[0025] S4, drying: the filter cake is introduced into the drying system for drying, the drying temperature is 150°C, and the drying time is 3 hours. The purity of the obtained quartz is 99.96% after testing.

[0026] S5. Waste acid purification: The generated waste acid is collected separately, and each waste acid is purified by evaporation and condensation for later use, including the following steps: S501, purify different types of previous waste acid separately, add sulfuric acid with a concentration range of 50% into the evaporator, the evaporator is made of steel lined with PTFE; S502, adding the waste acid into an evaporator to evaporate the mixed acid of sulfuric acid and the waste acid, controlling the vacuum degree of the evaporator to -700 mm Hg and the temperature to 70° C., recovering the evaporated gas by condensation to obtain recovered acid; S503. After testing the recovered acid, it is prepared according to the concentration required for acid purification and used as the corresponding type of reaction acid. The pipes and valves in the system that come into contact with sulfuric acid, waste acid and recovered acid are all made of PVDF.

[0027] S6. Wastewater purification: The generated wastewater is recycled to the wastewater pool, and the wastewater is purified and used in accordance with the industrial wastewater treatment method, including the following steps: S601, adjust the pH value: add 3% calcium hydroxide, 4% sodium hydroxide and 3.5% sodium carbonate to the wastewater to neutralize the acid in the wastewater and adjust the pH value to 10; S602, flocculation sedimentation: add 3 mg / L PAC and 0.2 mg / L PAM to the neutralized wastewater to accelerate the aggregation of colloidal particles in the water, and remove part of the sediment and suspended matter after sedimentation in the sedimentation tank; S603, multi-stage filtration and impurity removal: the precipitated wastewater is filtered through quartz sand and ultrafiltration in turn to remove part of the precipitate and suspended matter; calcium ions, fluoride ions and heavy metals are removed through ion exchange resin; ions and impurities in the water are removed through two-stage reverse osmosis; finally, EDI purification and desalination are carried out to make the wastewater reach the ultrapure water standard and meet the conditions required for the previous acid purification reaction. After passing the test, it is directly used as water for the previous step. Example

[0028] The difference from the first embodiment is that: S1. Add 3500 ml of hydrochloric acid with a concentration of 4.87 mol / L and control the temperature in the reactor to 80°C.

[0029] S2. The amount of clean water added each time is 3500ml.

[0030] S3, the concentration of hydrofluoric acid is 0.91mol / L, and the temperature in the reactor is controlled at 80°C; Add 2500ml of nitric acid with a concentration of 1.34mol / L, control the temperature in the reactor to 80°C, and add 2500ml of clean water each time; Add 3500ml of hydrochloric acid for reaction, the concentration of hydrochloric acid is 4.87mol / L, the temperature in the reactor is controlled at 80℃, and the amount of clean water added each time is 3500ml; Add 2500 ml of nitric acid with a concentration of 1.34 mol / L, control the temperature in the reactor to 80°C, and add 2500 ml of clean water each time.

[0031] S4. The purity of the obtained quartz was 99.91% after testing.

[0032] S502, control the vacuum degree of the evaporator to -730 mm Hg and the temperature to 85°C.

[0033] S601. Adjust the pH value: Add 2% calcium hydroxide, 3.5% sodium hydroxide and 3.5% sodium carbonate to the wastewater.

[0034] S602, flocculation sedimentation: add 2.5 mg / L PAC and 0.15 mg / L PAM to the neutralized wastewater. Example

[0035] The difference from the first embodiment is that: S1. Add 4000 ml of hydrochloric acid with a concentration of 3.52 mol / L, control the temperature in the reactor to 90°C, and cool to 30°C after 40 minutes of reaction.

[0036] S2. The amount of clean water added each time is 4000ml.

[0037] S3, add 5000ml of hydrofluoric acid, the concentration of hydrofluoric acid is 1.06mol / L, control the temperature in the reactor to 90℃, cool to 30℃ after 40min reaction time, and add 5000ml of clean water each time; Add 4000ml of nitric acid with a concentration of 1.63mol / L, control the temperature in the reactor at 90°C, cool to 30°C after 40min of reaction, and add 4000ml of clean water each time; Add 4000ml of hydrochloric acid to the reaction, the concentration of hydrochloric acid is 3.52mol / L, control the temperature in the reactor at 90℃, cool to 30℃ after 40min of reaction time, and add 4000ml of clean water each time; 4000 ml of nitric acid was added, the concentration of nitric acid was 1.63 mol / L, the temperature in the reactor was controlled at 90°C, and after 40 min of reaction time, the temperature was lowered to 30°C. The amount of clean water added each time was 4000 ml.

[0038] S4, drying temperature 200 ° C, drying time 2h, the obtained quartz is tested to have a purity of 99.92%.

[0039] S502, control the vacuum degree of the evaporator to -760 mm Hg and the temperature to 90°C.

[0040] S601. Adjust the pH value: Add 2% calcium hydroxide, 3% sodium hydroxide and 3.5% sodium carbonate to the wastewater.

[0041] S602, flocculation sedimentation: add 2.5 mg / L PAC and 0.2 mg / L PAM to the neutralized wastewater.

[0042] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0043] In the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0044] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] The term "comprise" or any other similar term is intended to cover a non-exclusive inclusion, such that a process, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, article, or apparatus / device.

[0046] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A high-purity quartz sand purification process, characterized in that: The following steps are involved: S1, acid purification: add the quartz sand raw material into the reactor, add the reaction acid into the reactor according to a certain solid-liquid ratio, heat the reactor for a period of time and then cool it down to dissolve the impurities in the quartz; S2, filter press cleaning: the acid-washed material is sent to the plate and frame filter press to form a filter cake, the filter cake is washed with clean water 1 to 4 times, and the filter cake is sent to the plate and frame filter press again; S3, repeat the acid purification and filter pressing cleaning several times until all acids in the process are used up; S4, drying: the cleaned filter cake is put into the drying system for drying to obtain high-purity quartz sand with a purity of ≥99.9%; S5. Waste acid purification: the generated waste acid is collected separately, and each waste acid is purified by evaporation and condensation for later use; S6. Wastewater purification: The generated wastewater is recycled into the wastewater pool, and the wastewater is purified and set aside in the same way as industrial wastewater treatment.

2. A high-purity quartz sand purification process according to claim 1, characterized in that: In S1, the reaction acids are hydrochloric acid, hydrofluoric acid, nitric acid, hydrochloric acid, and nitric acid in the order of only one each time for acid purification.

3. A high-purity quartz sand purification process according to claim 2, characterized in that: The hydrochloric acid concentration ranges from 3 to 6 mol / L, and the reaction time ranges from 20 to 60 min.

4. A high-purity quartz sand purification process according to claim 2, characterized in that: The hydrofluoric acid concentration ranges from 0.5 to 2 mol / L, and the reaction time ranges from 20 to 50 min.

5. A high-purity quartz sand purification process according to claim 2, characterized in that: The nitric acid concentration ranges from 1 to 3 mol / L, and the reaction time ranges from 20 to 60 min.

6. A high-purity quartz sand purification process according to claim 1, characterized in that: In S1 and S3, the solid-liquid ratio of the first acid purification and acid addition is in the range of 1:7-10, the solid-liquid ratio of the repeated acid purification and acid addition is in the range of 1:8-12, and the reaction temperature in the reactor is in the range of 50-90°C.

7. A high-purity quartz sand purification process according to claim 1, characterized in that: In S2, the amount of clean water used for each cleaning is the same as the amount of the corresponding reaction acid.

8. A high-purity quartz sand purification process according to claim 1, characterized in that: In S4, the drying temperature in the drying system ranges from 150 to 200°C.

9. A high-purity quartz sand purification process according to claim 1, characterized in that: In S5, the waste acid purification comprises the following steps: S501, purifying different types of previous waste acids respectively, and adding sulfuric acid with a concentration range of 20-80% into the evaporator; S502, adding waste acid to an evaporator to evaporate a mixed acid of sulfuric acid and waste acid, controlling the vacuum degree and temperature of the evaporator, wherein the vacuum degree ranges from -760 mm to -680 mm of mercury, and the temperature ranges from 70 to 100° C., and recovering the evaporated gas by condensation to obtain recovered acid; S503. After testing the recovered acid, it is prepared according to the concentration required for acid purification and used as the corresponding type of reaction acid.

10. A high-purity quartz sand purification process according to claim 1, characterized in that: In S6, wastewater purification comprises the following steps: S601, adjusting pH value: adding one or more of calcium hydroxide, sodium hydroxide or sodium carbonate in a concentration range of 2-4% to 3-5% to the wastewater to neutralize the acid in the wastewater and adjust the pH value to 9-11; S602, flocculation sedimentation: adding a certain amount of one or more flocculants PAC or PAM to the neutralized wastewater, the amount of PAC added is in the range of 2~5mg / L, and the amount of PAM added is in the range of 0.1~0.5mg / L, and after sedimentation in the sedimentation tank, part of the sediment and suspended matter are removed; S603, multi-stage filtration and impurity removal: The precipitated wastewater is filtered through quartz sand and ultrafiltration in turn, and then the calcium ions, fluoride ions and heavy metals are removed through ion exchange resin, and then it goes through two-stage reverse osmosis, and finally EDI purification and desalination, so that the wastewater reaches ultrapure water standards.

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