Iron removal process in low-iron quartz sand production

Abstract

The iron removal process in the low-iron quartz sand production takes crushed quartz sand as a raw material, and comprises the following steps: S1, weighing the quartz sand through a belt conveyor; s2, mixing the weighed quartz sand with water, wherein the weight ratio of the water to the quartz sand is 7: 3; s3, screening the mixed sand-water mixture through a drum screen; large impurity particles with the particle size of 0.75 mm or above are removed; s4, the screened sand-water mixture is subjected to iron removal through a vertical ring high-gradient magnetic separator; s5, the water-sand mixture passing through the vertical ring high-gradient magnetic separator passes through a spiral chute; and S6, the sand-water mixture obtained in the step S5 is injected into a reaction tank, a plurality of ultrasonic oscillators are fixedly installed in the reaction tank, the ultrasonic oscillators are started, carbon dioxide gas is continuously input from a gas inlet pipe, water is continuously input from a water inlet pipeline, continuous reaction is conducted for 1-3 hours, after the reaction is finished, materials are discharged, dehydration is conducted, and the low-iron quartz sand is obtained. The process is good in effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the production of quartz sand, in particular to a de-ironing process in the production of low-iron quartz sand for photovoltaic ultra-white glass. BACKGROUND

[0002] The use of quartz sand is mainly affected by the iron content (calculated as Fe2O3) and the purity of silicon dioxide. The lower the iron content and the higher the purity, the higher the technical threshold of the application scenarios. For example, the application of ultra-white glass, photovoltaic glass, optical glass (lenses, prisms) usually requires (Fe2O3 < 0.01%), that is, the iron content (calculated as Fe2O3) is less than 100 ppm. Most conventional ordinary quartz sand is ordinary quartz sand after natural mining, crushing and washing. The Fe2O3 content is concentrated in the range of 0.02% to 0.06%, which is the most common iron content range in mining quartz sand. The iron content of some high-quality mineral deposits is extremely low. For example, a certain place in Guangxi is an important raw material base for low-iron quartz sand for ultra-white glass. The average iron content of gravel ore after washing is ≤30 ppm (0.003%), and the average iron content of coarse sand ore after washing is ≤52 ppm (0.0052%). This kind of raw ore has excellent quality, but the production area is small, the yield is low, and the price is high. Due to the obvious transportation cost from the production area to the use area, this kind of quartz sand is not practical for many manufacturers. To meet the requirements of ultra-white photovoltaic glass for low-iron quartz sand, most manufacturers use ordinary quartz sand to remove iron to meet the requirements of the raw material. For quartz sand with an iron content of less than 100 ppm for ultra-white glass, ordinary quartz sand with an iron content of 200 ppm or less is usually used after iron removal to meet the requirements. For quartz sand with an iron content of more than 100 ppm and less than 150 ppm, ordinary quartz sand with an iron content of 350 ppm or less is usually used after iron removal. The corresponding particle size of the quartz sand is 0.1 to 0.75mm (the smaller the particle, the relatively easier to reduce the iron content), currently in the quartz sand iron removal process, generally first use physical iron removal and then use acid leaching process, the acid used is hydrochloric acid, sulfuric acid, oxalic acid and hydrofluoric acid combined use, the quartz sand is mixed with hydrochloric acid, sulfuric acid, oxalic acid, hydrofluoric acid and other acid solution to react, dissolve the iron or iron-containing minerals wrapped on the surface of the quartz particles, and can reduce the iron content to below 100ppm, this generally uses strong acid or hydrofluoric acid, the environment is not friendly during the treatment process, and waste treatment is needed after the treatment with hydrofluoric acid, there are also various methods for removing iron from quartz sand disclosed in Chinese patent documents, such as the iron removal method for quartz sand for photovoltaic glass disclosed in CN115367994A, which uses strong acid hypochlorous acid, CN117567023A discloses a production process for processing quartz sand into super white sand, which uses mixed medicine water, the treatment cost is high, CN105880213A discloses an ultrasonic iron removal process for quartz sand, which claims that the iron removal rate reaches 100% for 20 micron diameter, in this process, oxalic acid is used to dissolve fine or wrapped iron impurities due to its chelating property, because the price of oxalic acid is high, the cost is high in large-scale production, and this process is difficult to achieve when the initial iron content of the raw material is high, in addition to the above-mentioned environmental unfriendly, high initial iron content of the raw material and other problems, the quartz sand treated by the acid pickling iron reduction process also has a significant negative impact on the service life of the glass furnace, because the traditional acid pickling obtained quartz sand contains residues such as chlorine, sulfur and fluorine, which can corrode the refractory material of the glass furnace, years of operation practice has proved that the service life of the furnace operated by low-iron quartz sand obtained by acid pickling is only 60-70% of the normal service life, which significantly increases the cost of the furnace. SUMMARY

[0003] The purpose of the present application is to provide an iron removal process in the production of low-iron quartz sand.

[0004] To achieve the purpose of the present application, the following technical solution is adopted: an iron removal process in the production of low-iron quartz sand, using crushed quartz sand as raw material, comprising the following steps: S1: the quartz sand is weighed by a belt conveyor; S2: the weighed quartz sand is mixed with water, and the weight ratio of water to quartz sand is 7:3; S3: the mixed sand-water mixture is sieved by a rotary screen; remove large impurity particles larger than 0.75mm; S4: the sieved sand-water mixture is removed by a vertical ring high gradient magnetic separator; S5: the sand-water mixture after the vertical ring high gradient magnetic separator is removed by a spiral chute, and the material with a specific gravity greater than 3.5g / cm³ is removed; S6: the sand-water mixture obtained in step S5 is injected into a reaction tank, the bottom of the reaction tank is connected with a water inlet pipeline, a valve is connected on the water inlet pipeline, and an air inlet pipeline is also connected on the water inlet pipeline; an overflow pipe is installed on the reaction tank, and a plurality of ultrasonic oscillators are fixedly installed in the reaction tank; the ultrasonic oscillators are turned on, carbon dioxide gas is continuously input from the air inlet pipeline, and water with an iron content lower than 10 ppm is continuously input from the water inlet pipeline; the reaction is continuously carried out for 1-3 hours, water in the reaction tank flows out from the overflow pipe during the reaction, and the material is dehydrated after the reaction is completed, so that low-iron quartz sand is obtained.

[0005] Further, the weight ratio of the quartz sand to water in the reaction tank is 6:3.5-4.5.

[0006] Further, the ultrasonic oscillation power configured on the reaction tank is 35-45 times the tonnage of the quartz sand, the unit of the ultrasonic oscillation power is W, and the ultrasonic oscillation power per unit area on the horizontal section of the reaction tank is 180-250 W / m 2 ; the ultrasonic oscillation frequency is 50 kHz.

[0007] Further, the amount of carbon dioxide is W=TxCx(0.02-0.03), wherein T is the weight of the quartz sand, the unit is ton; C is the reduction value of the iron content of the quartz sand, the unit is ppm; the dimension does not participate in the calculation, the unit of W is kg, and the carbon dioxide is input at a uniform speed.

[0008] Further, the weight of the input water is 0.6-0.8 times the weight of the quartz sand.

[0009] Further, the particle size of the quartz sand is 0.1-0.71 mm, and the average particle size is 0.3-0.4 mm.

[0010] Further, the iron content in the quartz sand is greater than 220 ppm and less than or equal to 228 ppm, and the iron content in the quartz sand after iron removal is less than 100 ppm.

[0011] Further, the iron content in the quartz sand is greater than 190 ppm and less than or equal to 196 ppm, and the iron content in the quartz sand after iron removal is less than 80 ppm.

[0012] Further, the iron content in the quartz sand is greater than 430 ppm and less than 435 ppm, and the iron content in the quartz sand after iron removal is less than 150 ppm.

[0013] The positive beneficial technical effect of the present application is that the process uses carbon dioxide to react with iron in the quartz sand to achieve the purpose of removing iron, the carbonic acid itself is a weak acid and is easy to decompose, and will not form harmful residues in the quartz sand, and the process will not produce harmful waste, and through tests, the process has a wider process range, which will be described in detail in combination with the specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a schematic diagram of the reaction tank used in the present application.

[0015] Figure 2 is a flow chart of the present application. DETAILED DESCRIPTION

[0016] In order to more fully explain the implementation of the present application, the implementation examples of the present application are provided, which are only an illustration of the present application and do not limit the scope of the present application.

[0017] In the drawings, each mark is: 1: reaction tank; 2: ultrasonic oscillator; 3: air inlet pipe; 4: water inlet pipe; 5: quartz sand; 6: water; 7: overflow pipe.

[0018] The reaction tank used in the present application has a diameter of 4m, and 35 ultrasonic oscillators are arranged inside, each having a power of 70W, 60 tons of quartz sand are fed into the reaction tank at a time, the weight ratio of the quartz sand to water in the reaction tank is 6:4, when the quartz sand in the reaction tank reaches between 20 tons and 30 tons, the ultrasonic oscillators are turned on and water and carbon dioxide are fed from the bottom to react and remove iron, when the quartz sand in the reaction tank reaches 60 tons, the feeding is stopped, the reaction is carried out at normal temperature and pressure, and the water overflowed from the reaction tank can be recycled after flocculation treatment.

[0019] An iron removal process in low-iron quartz sand production, using crushed quartz sand as raw material, the particle size of the raw quartz sand is 0.1-0.71mm, and the average particle size is 0.3-0.4mm, including the following steps: S1: the quartz sand is weighed by a belt conveyor; S2: the weighed quartz sand is mixed with water, and the weight ratio of water to quartz sand is 7:3; S3: the mixed sand-water mixture is sieved by a drum screen; remove large impurity particles larger than 0.75mm; S4: the sieved sand-water mixture is removed by a vertical ring high gradient magnetic separator; S5: the sand-water mixture after the vertical ring high gradient magnetic separator is removed by a spiral chute, and the material with a specific gravity greater than 3.5g / cm³ is removed; S6: the sand-water mixture obtained in step S5 is injected into a reaction tank, the bottom of the reaction tank is connected with a water inlet pipeline, a valve is connected on the water inlet pipeline, and an air inlet pipe is also connected on the water inlet pipeline; an overflow pipe is installed on the reaction tank, and a plurality of ultrasonic oscillators are fixedly installed in the reaction tank, the ultrasonic oscillators are turned on, carbon dioxide gas is continuously input from the air inlet pipe, water is continuously input from the water inlet pipeline, the iron content in the water is less than 10 ppm, and the continuous reaction is carried out for 1-3 hours; during the reaction, the water in the reaction tank flows out from the overflow pipe, after the reaction is completed, the discharged material is dehydrated, and low-iron quartz sand is obtained.

[0020] The above process is used to treat raw sand (raw material quartz sand) with different iron contents, and the results are as follows:

[0021] Example 1: .

[0022] Example 2: .

[0023] Example 3: .

[0024] Example 4:

[0025] Example 5:

[0026] The reaction time of example 1 and example 2 is 80 minutes, the reaction time of example 3, example 4 and example 5 is 90 minutes, and the reaction end time is determined by multiple tests that the iron content basically does not change. The raw sand in the examples refers to the raw material quartz sand, and the treated refers to the quartz sand after iron removal by the process, and the data in the examples is the percentage content.

[0027] From the above examples, it can be seen that the process of the present application has a wider range. The traditional pickling (acid dissolution) iron removal process reduces the iron content to 150 ppm, which requires the iron content of the original sand to be about 350 ppm. However, the present process can reduce the iron content of the original sand of more than 450 ppm to 150 ppm. Since the higher the iron content, the lower the price of the original sand, and vice versa, the use of the process of the present application can greatly increase the added value of the original sand. In the production of solar super white glass, the iron content of the quartz sand is required to be below 100 ppm. The traditional pickling (acid dissolution) process uses original sand with an iron content of generally 190-200 ppm. However, the present process can widen the iron content standard of the original sand to more than 220 ppm, greatly reducing the cost of the original sand. The traditional pickling (acid dissolution) process is used for the iron removal of solar super white glass raw materials (Example 3, Example 4). The use of the present process can reduce the iron content to below 80 ppm. The quartz sand with an iron content of below 80 ppm is significantly higher in price than the quartz sand with an iron content of 100 ppm. Moreover, the carbon dioxide used in the present process is low in price, the treatment process is pollution-free, there is no ion residue of corrosion-resistant materials after treatment, and there is no impact on the service life of the glass kiln.

[0028] After the embodiments of the present application are described in detail, those skilled in the art can clearly understand that various changes and modifications can be made without departing from the scope and spirit of the above application. Any simple modification, equivalent change and modification made according to the technical essence of the present application to the above examples are within the scope of the technical solution of the present application, and the present application is not limited to the implementation modes of the examples shown in the specification.

Claims

1. An iron removal process in the production of low-iron quartz sand, using crushed quartz sand as raw material, comprising the following steps: S1: Quartz sand is weighed via a belt conveyor; S2: The weighed quartz sand is mixed with water, and the weight ratio of water to quartz sand is 7:

3. S3: The mixed sand-water mixture is screened through a drum screen to remove large impurity particles larger than 0.75mm; S4: The sieved sand-water mixture is then passed through a vertical ring high-gradient magnetic separator to remove iron. S5: The water-sand mixture after passing through the vertical ring high gradient magnetic separator is passed through a spiral chute to remove particles with a specific gravity greater than 3.5 g / cm³. 3 Substances; S6: Inject the sand-water mixture obtained in step S5 into a reaction tank. The bottom of the reaction tank is connected to a water inlet pipe, which is connected to a valve and an air inlet pipe. An overflow pipe is installed on the reaction tank. Multiple ultrasonic oscillators are fixedly installed inside the reaction tank. Turn on the ultrasonic oscillators, continuously input carbon dioxide gas from the air inlet pipe, and continuously input water from the water inlet pipe. The iron content in the water is less than 10 ppm. The water carries carbon dioxide into the reaction tank and reacts continuously for 1-3 hours. During the reaction, the water in the reaction tank flows out from the overflow pipe. After the reaction is completed, the material is released for dehydration to obtain low-iron quartz sand.

2. The iron removal process in the production of low-iron quartz sand according to claim 1, characterized in that: When the weight ratio of quartz sand to water in the reaction vessel is 6:3.5-4.

5.

3. The iron removal process in the production of low-iron quartz sand according to claim 1, characterized in that: The ultrasonic vibration power configured on the reaction vessel is 35-45 times the tonnage of the quartz sand. The unit of ultrasonic vibration power is W, and the ultrasonic vibration power per unit area on the horizontal cross-section of the reaction vessel is 180-250 W / m. 2 The ultrasonic oscillation frequency is 50 kHz.

4. The iron removal process in the production of low-iron quartz sand according to claim 1, characterized in that: The amount of carbon dioxide used is: W = T × C × (0.02 - 0.03), where T is the weight of the quartz sand in tons; C is the reduction in the iron content of the quartz sand in ppm; dimensions are not involved in the calculation, and the unit of W is kg. The carbon dioxide is input at a constant rate.

5. The iron removal process in the production of low-iron quartz sand according to claim 1, characterized in that: The weight of the input water is 0.6-0.8 times the weight of the quartz sand.

6. The iron removal process in the production of low-iron quartz sand according to claim 1, characterized in that: The quartz sand has a particle size of 0.1-0.71 mm and an average particle size of 0.3-0.4 mm.

7. The iron removal process in the production of low-iron quartz sand according to claim 6, characterized in that: The iron content in the quartz sand is greater than 220 ppm and less than or equal to 228 ppm, and the iron content in the quartz sand after iron removal is less than 100 ppm.

8. The iron removal process in the production of low-iron quartz sand according to claim 6, characterized in that: The iron content in the quartz sand is greater than 190 ppm and less than 196 ppm, and the iron content in the quartz sand after iron removal is less than 80 ppm.

9. The iron removal process in the production of low-iron quartz sand according to claim 6, characterized in that: The iron content in the quartz sand is greater than 430 ppm and less than 435 ppm, and the iron content in the quartz sand after iron removal is less than 150 ppm.

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