Method for preparing 99.99% quartz sand by using river channel yellow sand as raw material

Abstract

The present application relates to a kind of river yellow sand as raw material preparation 99.99% quartz sand method, first to river yellow sand raw material is sand making and pretreatment, make the SiO2 of quartz raw material treated ≥99%;The obtained quartz raw material is first pickled, and the pickling solution is composed of HF and high ferric salt composite acid solution;The obtained quartz raw material is mixed with wood carbon powder, and the temperature is kept at 1000±50 DEG C for 30-45 min, after baking, cooling;The obtained quartz raw material is second pickled, and the pickling solution is composed of hydrochloric acid and EDTA composite acid solution, after pickling, washing, drying, obtain the SiO2 purity not less than 99.99% quartz sand.The present application can be extracted from low quartz content river yellow sand with the purity of 99.99% high-purity quartz sand, and process is simple, without high-temperature chlorination process.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing 99.99% quartz sand using river channel yellow sand as raw material, belonging to the technical field of non-metallic mineral deep processing. BACKGROUND

[0002] At present, high-purity quartz sand products of 99.99% and above are mostly produced using high-quality vein quartz ore, high-purity quartzite, and pebbles with high silica content as raw materials, and there are also some using granite pegmatite as raw material. With years of mining, high-grade quartz resources are becoming less and less. Therefore, it is urgent to broaden the high-purity quartz raw material. The river channel yellow sand resource is abundant in China, but the quartz content of river channel yellow sand is low, mainly composed of a small amount of quartz and a large amount of feldspar, among which the quartz content is generally less than 50%, and the metal content of feldspar (including potassium feldspar, sodium feldspar, and plagioclase) is high, among which a large amount of Al 3+ , Ti 4+ , etc. impurity ions are similar in ionic radius to Si 4+ , Al 3+ ions in quartz lattice, which are difficult to separate by physical methods.

[0003] The sand and stone resources such as yellow sand in the river channel are abundant, and are one of the important siliceous raw material resources. The silica content in high-quality yellow sand can reach about 70%, and other impurities include a small amount of soil, feldspar, magnetite, ilmenite, limonite, mica sheet, etc. It is a natural and high-quality silica sand resource. If the river sand is not comprehensively treated and utilized, it will accumulate in the riverbed year after year, raising the riverbed and water level, and causing floods to the people on both sides of the riverbed during the rainy season. At present, the yellow sand in the river channel is mostly used as cement concrete, cement floor, cement brick, ash sand brick, and cement pole building materials, and a small amount is used as pesticide granules and casting sand materials. The economic value of yellow sand is low. How to scientifically and reasonably develop these river channel yellow sand resources, dredge the river channel to prevent floods, and process and utilize them to improve their economic benefits, has special significance.

[0004] Patent CN1111097C discloses a method for purifying quartz sand from river silt, which comprises seven process steps of opening slurry, screening, weak magnetic primary selection, heavy sand separation, cylinder deslagging, strong magnetic separation, light sand separation and coarse product selection to obtain SiO2≥98% quartz sand. However, this method cannot fundamentally solve the problem of separation of mica and feldspar, and the use of the product quartz sand is greatly limited; and the feldspar sand and iron ore contained in the yellow sand are not further recycled and utilized, but are used as by-products for building raw materials, which does not maximize the utilization value and best economic benefit of the yellow sand. Patent CN103372496A discloses a process for separating quartz sand, feldspar sand and iron powder from river sand, which solves the above problems, but still cannot solve the quality standard requirements of the separated quartz sand containing less than 0.008% of Fe2O3 and the feldspar sand containing less than 0.02% of Fe2O3, and the quality standard requirements of the artificial quartz stone plate sand. Therefore, it has become one of the important tasks for technical personnel in the field of siliceous material technology to scientifically and reasonably develop and utilize the cheap yellow sand resources in the river to maximize the utilization value and best economic benefit. SUMMARY

[0005] The purpose of the present application is to provide a method for preparing 99.99% quartz sand from cheap river yellow sand.

[0006] The solution adopted by the present application to solve the above technical problems is:

[0007] A method for preparing 99.99% quartz sand from river yellow sand, comprising the following steps:

[0008] (1) preparing sand and pretreating the river yellow sand raw material;

[0009] (2) performing first acid washing on the quartz raw material obtained in step (1), and the acid washing liquid is a composite acid liquid composed of HF and high ferrate;

[0010] (3) mixing the quartz raw material obtained in step (2) with carbon powder, and baking at 1000±50℃ for 30-45min, and then cooling after baking;

[0011] (4) performing second acid washing on the obtained quartz raw material, and the acid washing liquid is a composite acid liquid composed of halogen acid and heavy metal complexing agent, and after acid washing, washing with water and drying to obtain quartz sand with SiO2 purity not less than 99.99%.

[0012] Further, the pretreatment process in step (1) is selected from one or both of magnetic separation and flotation. The purpose of pretreatment is mainly to remove feldspar and other aluminum silicate minerals, and impurities such as pyrite minerals in the river yellow sand raw material.

[0013] Further, the pre-treatment process of step (1) comprises at least one magnetic separation and at least one flotation.

[0014] Further, the magnetic separation uses an electromagnetic field with a magnetic field strength of 13000-18000 Gauss.

[0015] Further, the flotation uses HF as an activator and regulator, and dodecylamine as a collector, and is performed at a pH of 2.0-2.5. The feldspar and other organic impurities are floated out with the foam.

[0016] Further, the quartz sand obtained after each flotation is subjected to X-ray phase analysis, and the flotation is stopped when the feldspar content in the quartz sand is less than 1%.

[0017] Further, step (1) uses grinding to produce sand. For example, rod mill grinding. The grinding process fully dissociates the quartz and other minerals in the coarse-grained river sand, and the dissociated sand is classified to select the part with a particle size range of 60-150 mesh as the quartz raw material for the next step.

[0018] Further, the SiO2 content in the quartz raw material after the pre-treatment of step (1) is ≥99%.

[0019] Further, the first acid washing is performed at a temperature of 80±5℃ for 3-4 hours, and the second acid washing is performed at a temperature of 80±5℃ for 3-4 hours.

[0020] The first acid washing is an oxidizing acid washing, which aims to remove the residual aluminum silicate minerals and pyrite minerals in the quartz raw material, so that the SiO2 content in the purified quartz sand is ≥99.9%. The HF removes the residual aluminum silicate mineral impurities in the quartz sand, and the strong oxidizing property of sodium ferrate can oxidize and decompose the sulfide mineral impurities, thereby improving the quartz sand and increasing the whiteness of the quartz sand to meet the standard requirements for quartz sand for artificial stone slabs.

[0021] Further, after the acid washing of step (2), the quartz raw material is subjected to deacidification and washing with tap water until neutral.

[0022] Further, the halogen acid in step (4) is hydrochloric acid, and the heavy metal complexing agent is EDTA.

[0023] Further, after the acid washing of step (4), the quartz raw material is subjected to deacidification, washing with tap water until neutral, washing with electronic-grade pure water at least three times, and then drying.

[0024] Further, the mass fraction of HF in the composite acid solution used in the first acid washing is 10%-30%, and the mass fraction of sodium ferrate is 0.001%-1%, and is further preferably 0.001%-0.1%.

[0025] Further, the high ferrate is selected from sodium ferrate or potassium ferrate.

[0026] Further, the mass fraction of halogen acid in the composite acid solution used for the second acid washing is 20% to 30%, and the mass fraction of the metal complexing agent is 0.01% to 0.05%.

[0027] Further, step (3) cools the material to the second acid washing temperature or a temperature not higher than 25°C than the second acid washing temperature. For example, the second acid washing temperature is 80±5°C, and step (3) can cool the material to 95-105°C.

[0028] Further, the carbon powder used in step (3) is selected from wood carbon powder, coke carbon powder or activated carbon powder sold on the market.

[0029] Further, the mass of the carbon powder used in step (3) is 0.5% to 2% of the mass of the quartz raw material, for example, 0.8% or 1%.

[0030] The purpose of high-temperature roasting in step (3) is to remove the gas-liquid inclusions in the quartz, and the acid washing with the composite acid solution composed of halogen acid + heavy metal complexing agent in step (4) can remove the metal and alkali metal and alkaline earth metal impurities in the quartz raw material, so that the purity of the final product SiO2 is not less than 99.99%, and high-temperature chlorination is not needed.

[0031] The present application uses a combination of physical and chemical methods, has a high impurity removal rate, a low loss rate of quartz sand, realizes the upgrading of the product with less equipment investment, and produces quartz sand with high purity, which can be used not only as a raw material for photovoltaic ultra-white glass but also for preparing high-value-added artificial quartz plate sand, such as crystal glass, crystal glass, high-grade ceramics, high-boron glass tube, electronic and electrical silicon powder, and can also be used for tap water filtration and artificial quartz plate sand. The purity problem of the quartz sand purified from the river sand is solved, and the industrial use of the quartz sand purified from the river sand is greatly expanded. DETAILED DESCRIPTION

[0032] In order to better understand the present application, the following examples are further illustrations of the present application, but the content of the present application is not limited to the following examples.

[0033] Example 1

[0034] Take the river sand in Macheng City, Hubei Province as an example.

[0035] 1. Select coarse particles (2-40 mesh) river sand as raw material for X-ray phase analysis, and the analysis result shows that the quartz content is 35%, and the others are potassium feldspar, sodium feldspar and plagioclase minerals.

[0036] 2. Raw material quartz sand pretreatment:

[0037] a, sand making + magnetic separation: rod mill is used for grinding, wet classification is carried out by using 60 mesh cylinder screen as upper screen and 150 mesh cylinder screen as lower screen, 60-150 mesh slurry is collected, and most of the undersize of the 150 mesh screen is feldspar powder which can be purified and utilized separately. The screened quartz raw material is subjected to iron removal by 13000 gauss electromagnetic separation and 18000 gauss electromagnetic separation, and the slurry after iron removal is dehydrated for flotation;

[0038] b, flotation: HF is used as activator and pH regulator, and dodecylamine is used as collector (dosage is 500 g / t), and flotation is carried out under the condition of pH = 2.0. After each flotation, the obtained quartz sand is subjected to X-ray phase analysis, and after 6 times of flotation, the content of feldspar minerals in the quartz sand is less than 1%, and the flotation is stopped, and the quartz sand is washed and dehydrated for standby use.

[0039] 3, acid pickling to remove aluminosilicate and pyrite impurities: the quartz sand after flotation is subjected to dynamic acid pickling at 80°C for 3 hours by using a composite acid liquid composed of 18% HF and 0.02% sodium ferrate (acid pickling equipment is referred to patent CN201110247061.4). After acid pickling, the acid liquid is removed, and the quartz sand is washed with clean tap water until neutral, and then dehydrated for standby use. The content of SiO2 in the raw quartz sand is 99.92% as analyzed by sampling.

[0040] 4, the raw quartz sand after the first acid pickling is mixed with 1% wood carbon powder based on the mass of the quartz sand, and then uniformly mixed and baked at 1050°C for 30 minutes, and then cooled to 95°C for standby use.

[0041] 5, the quartz sand obtained in step 4 is subjected to acid pickling at 80°C for 3 hours by using a composite acid liquid composed of 30% hydrochloric acid and 0.01% EDTA, and then the acid liquid is removed, and then the quartz sand is washed with clean tap water until the washing water is neutral, and then washed with electronic grade pure water for three times, and then dehydrated for standby use.

[0042] 6, the material after the second acid pickling in step 5 is sent into a high-temperature drying device for drying, and then the quartz sand after drying is sampled and analyzed.

[0043] According to GB / T32649-2016 "High-purity quartz sand for photovoltaic use", the impurity elements in the obtained quartz sand product are detected by the impurity element detection method in GB / T3284-2015 "Quartz glass chemical composition analysis method". The sampling and testing methods of all examples in this application are the same, and the above standards are used.

[0044] The test results of the quartz sand product obtained in this example are: SiO2: 99.99%, aluminum: 22.3 ppm, iron: 0.5 ppm, potassium: 1.0 ppm; sodium: 1.2 ppm; calcium 0.9 ppm:; magnesium: 0.8 ppm; titanium: 2.4 ppm.

[0045] The quartz glass tube drawn by high-temperature electric melting using this sand as raw material has a hydroxyl content of 5 ppm according to the detection of GB / T 1242-2019 "Quartz Glass Hydroxyl Content Test Method".

[0046] Comparative Example 1

[0047] Different from Example 1, the composite acid solution used in step 3 is 18% HF + 0.02% oxalic acid. The SiO2 content in the raw material quartz sand after the first acid pickling is 99.8%. The test results of the final quartz sand product are: SiO2: 99.97%, aluminum: 37.8 ppm, iron: 7.5 ppm, potassium: 3.0 ppm; sodium: 4.2 ppm; calcium 15.5 ppm:; magnesium: 0.8 ppm; titanium: 6.4 ppm.

[0048] Comparative Example 2

[0049] Different from Example 1, the acid pickling solution used in step 5 is 30% hydrochloric acid. The test results of the final quartz sand product are: SiO2: 99.98%, aluminum: 46.3 ppm, iron: 3.5 ppm, potassium: 4.8 ppm; sodium: 6.1 ppm; calcium 16.8 ppm:; magnesium: 1.8 ppm; titanium: 8.5 ppm.

[0050] Example 2

[0051] Take the yellow sand of Shangba River in Xishui County, Hubei Province as an example.

[0052] 1. Select coarse particles (2-50 mesh) river sand as raw material for X-ray phase analysis. The analysis results show that the quartz content is 40%.

[0053] 2. Raw material quartz sand pretreatment:

[0054] a. Sand making + magnetic separation: rod mill is used for ore grinding, wet classification is carried out with 60 mesh cylinder screen as upper screen and 150 mesh cylinder screen as lower screen, and 60-150 mesh slurry is collected. The screened quartz raw material is subjected to iron removal by 13000 Gauss electromagnetic separation and 18000 Gauss electromagnetic separation, and the slurry after iron removal is dehydrated for flotation;

[0055] b, flotation: using HF as activator and regulator, and dodecylamine as collector (500 g / t), flotation was carried out at pH = 2.5, and the quartz sand obtained after each flotation was subjected to X-ray phase analysis, and after 6 times of flotation, the content of feldspar in the quartz sand was less than 1%, and the flotation was stopped, and after washing and dewatering, it was ready for use.

[0056] 3, acid washing to remove aluminosilicate and pyrite impurities: the quartz sand after flotation was subjected to dynamic acid washing at 85℃ for 4 hours with a composite acid solution composed of 16% HF and 0.01% potassium ferrate, and after acid washing, the acid solution was removed, and the sample was washed with clean tap water until it was neutral, and after dewatering, it was ready for use, and the SiO2 content in the raw quartz sand was 99.93%.

[0057] 4, mix the raw quartz sand after the first acid washing with 1% wood carbon powder by mass of the quartz sand, and bake at 1000℃ for 45 minutes, and after baking, cool to 105℃ for standby.

[0058] 5, the quartz sand obtained in step 4 is subjected to acid washing at 85℃ for 3.5 hours with a composite acid solution composed of 20% hydrochloric acid and 0.05% EDTA, and after acid washing, the acid solution is removed, and then washed with clean tap water until the washing water is neutral, and then washed with electronic grade pure water three times, and dewatered for standby.

[0059] 6, the material after the second acid washing in step 5 is sent to a high-temperature drying device for drying, and the quartz sand after drying is sampled and analyzed. Among them, SiO2: 99.99%, aluminum: 20.8 ppm, iron: 0.6 ppm, K: 1.1 ppm, sodium: 1.3 ppm, calcium: 0.8 ppm, magnesium: 0.9 ppm, titanium: 2.6 ppm.

[0060] The quartz glass tube drawn by high-temperature electric melting using this sand as raw material is detected according to GB / T1242-2019 "Quartz Glass Hydroxyl Content Test Method", and the hydroxyl content is 6 ppm.

[0061] Example 3

[0062] Take the river sand in Hong'an County, Hubei Province as an example.

[0063] 1. Select coarse particles (2-60 mesh) river sand as raw material for X-ray phase analysis, and the phase analysis results show that the quartz content is 36%.

[0064] 2, raw quartz sand pretreatment:

[0065] a, sand making + magnetic separation: rod mill is used for grinding, wet classification is carried out with 60 mesh cylinder screen as upper screen and 150 mesh cylinder screen as lower screen, and 60-150 mesh slurry is collected. The screened quartz raw material is subjected to iron removal by 13000 gauss electromagnetic separation and 18000 gauss electromagnetic separation, and the slurry after iron removal is dehydrated for flotation.

[0066] b, flotation: HF is used as activator and regulator, and dodecylamine is used as collector (800 g / t) for flotation under the condition of pH = 2.0. The quartz sand obtained after each flotation is subjected to X-ray phase analysis, and after 5 times of flotation, the content of feldspar in the quartz sand is less than 1%, and the flotation is stopped. After washing and dehydration, it is ready for use.

[0067] 3, acid pickling to remove aluminosilicate and pyrite impurities: the quartz sand after flotation is subjected to dynamic acid pickling at 80℃ for 4 hours with a composite acid solution composed of 16% HF and 0.01% sodium ferrate, and after acid pickling, the acid solution is removed, washed with clean tap water until neutral, and dehydrated for use. The SiO2 content in the raw quartz sand is 99.93%.

[0068] 4, mix the raw quartz sand after the first acid pickling with 1% wood carbon powder based on the mass of the quartz sand, and uniformly mix it at 1000℃ for 45 minutes, and after the roasting is completed, cool it to 105℃ for use.

[0069] 5, the quartz sand obtained in step 4 is subjected to acid pickling at 80℃ for 3.5 hours with a composite acid solution composed of 25% hydrochloric acid and 0.03% EDTA, and after acid pickling, the acid solution is removed, first washed with clean tap water until the washing water is neutral, then washed with electronic grade pure water three times, and dehydrated for use.

[0070] 6, the material after the second acid pickling in step 5 is sent to a high-temperature drying device for drying, and the quartz sand after drying is sampled and analyzed. Among them, SiO2: 99.99%, aluminum: 20.8 ppm, iron: 0.6 ppm, K: 1.1 ppm; sodium: 1.3 ppm; calcium 0.8 ppm:; magnesium: 0.9 ppm; titanium: 2.6 ppm.

[0071] The quartz glass tube drawn by high-temperature electric melting with this sand as raw material has a hydroxyl content of 6 ppm according to the detection of GB / T1242-2019 "Hydroxyl content test method for quartz glass".

[0072] Example 4

[0073] Take the river sand in Luotian County, Hubei Province as an example.

[0074] 1. Select coarse particles (2-30 mesh) river sand as raw material for X-ray phase analysis, and the analysis result shows that the quartz content is 45%.

[0075] 2, raw material quartz sand pretreatment:

[0076] a, sand making + magnetic separation: rod mill is used for grinding, wet classification is carried out with 60 mesh cylinder screen as upper screen and 150 mesh cylinder screen as lower screen, and 60-150 mesh slurry is collected. The screened quartz raw material is subjected to iron removal by 13000 gauss electromagnetic separation and 18000 gauss electromagnetic separation, and the slurry after iron removal is dehydrated for flotation;

[0077] b, flotation: HF is used as activator and regulator, and dodecylamine is used as collector (1000 g / t) for flotation under the condition of pH = 2.3. The quartz sand obtained after each flotation is subjected to X-ray phase analysis, and after 4 times of flotation, the content of feldspar in the quartz sand is less than 1%, and the flotation is stopped. After washing and dehydration, it is ready for use.

[0078] 3, acid pickling to remove aluminosilicate and pyrite impurities: the quartz sand after flotation is subjected to dynamic acid pickling with a composite acid solution composed of 20% HF and 0.02% sodium ferrate at a temperature of 80°C for 3 hours. After acid pickling, the acid solution is removed, washed with clean tap water until neutral, and dehydrated for standby use. The SiO2 content in the raw material quartz sand is 99.94%.

[0079] 4, mix the raw material quartz sand after the first acid pickling with 1.5% wood carbon powder based on the mass of the quartz sand, and uniformly mix it at a temperature of 1050°C for 30 minutes. After the roasting is completed, cool it to 95°C for standby use.

[0080] 5, the quartz sand obtained in step 4 is subjected to acid pickling with a composite acid solution composed of 28% hydrochloric acid and 0.02% EDTA at a temperature of 80°C for 3 hours. After acid pickling, the acid solution is removed, washed with clean tap water until the washing water is neutral, and then washed with electronic grade pure water three times, and dehydrated for standby use.

[0081] 6, the material after the second acid pickling in step 5 is sent to a high-temperature drying device for drying. The quartz sand after drying is sampled and analyzed. The SiO2 content is 99.99%, the aluminum content is 20.3 ppm, the iron content is 0.7 ppm, the potassium content is 1.0 ppm, the sodium content is 1.2 ppm, the calcium content is 0.7 ppm, the magnesium content is 0.5 ppm, and the titanium content is 2.2 ppm.

[0082] The quartz glass tube drawn by high-temperature electric melting with this sand as raw material is detected according to GB / T 1242-2019 "Quartz Glass Hydroxyl Content Test Method", and the hydroxyl content is 5 ppm.

[0083] The above is the preferred embodiment of the present application, of course, cannot be limited by the scope of the present invention, should be noted that for ordinary skilled in the art, without departing from the principles of the present invention, can also make a number of improvements and changes, these improvements and changes are also considered to be within the scope of the present invention.

Claims

1. A method for preparing 99.99% pure quartz sand from riverbed yellow sand, characterized in that, Includes the following steps: (1) The river sand raw material is processed and pretreated to ensure that the SiO2 content of the pretreated quartz raw material is ≥99%; (2) The quartz raw material obtained in step (1) is subjected to a first acid wash. The acid wash solution is a composite acid solution composed of HF and ferrate. (3) Mix the quartz raw material obtained in step (2) with carbon powder, and bake at 1000±50℃ for 30-45 minutes. After baking, cool. (4) The obtained quartz raw material is subjected to a second acid wash. The acid wash solution is a composite acid solution composed of halogen acid and heavy metal complexing agent. After the acid wash is completed, it is washed with water and dried to obtain quartz sand with SiO2 purity of not less than 99.99%.

2. The method according to claim 1, characterized in that, The pretreatment process in step (1) is selected from one or both of magnetic separation and flotation.

3. The method according to claim 1, characterized in that, The particle size range of the quartz raw material obtained from step (1) sand making is 60~150 mesh.

4. The method according to claim 1, characterized in that, The first pickling temperature is 80±5℃, and the pickling time is 3~4 hours; the second pickling temperature is 80±5℃, and the pickling time is 3~4 hours.

5. The method according to claim 1, characterized in that, The composite acid solution used for the first pickling contains HF with a mass fraction of 10% to 30% and ferrate with a mass fraction of 0.001% to 0.1%.

6. The method according to claim 1, characterized in that, The ferrate is selected from sodium ferrate or potassium ferrate.

7. The method according to claim 1, characterized in that, The composite acid solution used for the second pickling contains 20% to 30% halogen acid and 0.01% to 0.05% metal complexing agent.

8. The method according to claim 1, characterized in that, Step (3) Cool the material to the second pickling temperature or no more than 25°C higher than the second pickling temperature.

9. The method according to claim 1, characterized in that, The quartz raw material obtained after the first acid washing has SiO2 ≥ 99.9%.

10. The method according to claim 1, characterized in that, The mass of carbon powder used in step (3) is 0.5% to 1% of the mass of the quartz raw material.