Method for separating aluminosilicate minerals and purifying quartz sand under neutral conditions and its application

Abstract

The application discloses a method for separating aluminosilicate minerals and purifying quartz sand under neutral conditions and application thereof. The method for separating aluminosilicate minerals and purifying quartz sand under neutral conditions adopts one or more times of reverse flotation operations, and the reverse flotation operation comprises the following steps: adding a quartz depressor into quartz raw sand slurry or low-aluminum-content fine quartz sand slurry obtained through previous reverse flotation operation and mixing; then adding an aluminosilicate mineral collector and mixing; subsequently, adding a foaming agent under the condition of air agitation and stirring, and performing quartz reverse flotation, during which, stirring is kept and bubbles are scraped; and finally, washing the remaining slurry to obtain low-aluminum-content fine quartz sand. The reverse flotation process of the application is performed under neutral conditions, avoids the use of traditional strong acid and strong alkali, and further reduces the harm of the purification process to production equipment, ecological environment and operating personnel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-purity quartz sand preparation, and particularly relates to a method for separating aluminosilicate minerals and purifying quartz sand under neutral conditions and application thereof. BACKGROUND

[0002] High-purity quartz has excellent chemical stability, very low volume expansion coefficient, high temperature resistance, high insulation voltage capacity and the like due to its unique molecular chain structure, lattice shape and lattice change rule, and is an irreplaceable basic raw material in the fields of semiconductors, photovoltaics, optical fibers, electric light sources and the like, and plays a vital role, and has been listed as a strategic non-metallic mineral, so its preparation and purification process has important research significance. In industrial production, deep purification processing of quartz-rich raw ore is a conventional method for producing high-purity quartz with high economic value.

[0003] In natural quartz ore, a kind of aluminosilicate minerals is often associated. The mineral structure of this kind of mineral is very similar to that of quartz, which is formed by replacing one fourth of Si 4+ in the quartz structure with Al 3+ . This similar structure leads to similar physical and chemical properties between the two, which is not conducive to the purification and separation of minerals. In particular, when the aluminum content in quartz is high, the corresponding quartz products will have significantly reduced photoelectric properties, thereby affecting the quality of quartz products, and thus the content of aluminum in the raw material needs to be strictly controlled. Common aluminosilicate associated minerals mainly include feldspar, kaolin, zeolite, garnet, kyanite, sillimanite, mica and the like. Except for mica, aluminosilicate minerals cannot be dissolved and removed by high-concentration mixed acid (such as hydrofluoric acid and hydrochloric acid), nor do they have magnetism and can be separated by magnetic separation, so it is very challenging to realize efficient separation of quartz and aluminosilicate minerals.

[0004] Flotation is a very efficient and low-cost mineral separation process in mineral deep processing. The application of flotation to separate aluminosilicate minerals from quartz and then purify quartz is an effective strategy for preparing high-purity quartz sand. However, the existing flotation methods for separating quartz from aluminosilicate minerals face many problems: first, the flotation environment usually needs acid or alkali, which often causes equipment corrosion, environmental pollution, and even harm to operators; second, the commonly used collectors have poor water solubility (such as sodium oleate), which is easy to precipitate from water for a long time, affecting the addition amount of the collector, and the collectors used are often mixtures, and their interaction is complex, which makes the industrial flotation effect unsatisfactory; third, the existing flotation schemes are usually only for one kind of aluminosilicate mineral, such as the separation of feldspar and quartz, mica and quartz, etc., lacking systematic research on aluminosilicate minerals. In summary, the existing flotation schemes cannot meet the diversified needs of the high-purity quartz sand purification field, and therefore there is an urgent need to develop more efficient flotation methods for separating aluminosilicate minerals from quartz.

[0005] The patent specification with publication number CN108176518A discloses a neutral flotation method for purifying quartz minerals, which uses an amine, an organic halogenated acid, or an alkali solution of a halogenated salt as a mixture to separate iron oxide-stained quartz sand and iron-containing aluminosilicate minerals in quartz sand, and then obtain high-purity quartz concentrate.

[0006] The patent specification with publication number CN110127708A discloses a purification method for SiO2 purity ≥ 99.99% high-purity quartz sand, including flotation, high-temperature activation and water quenching, high-temperature alkali washing, high-temperature oxidation and acid washing, etc. The flotation reagent used in the flotation process is dodecylamine and its corresponding quaternary ammonium salt, No. 2 oil as a foaming agent, and phenylethyl ester oil. Under the condition of pH 2.0-3.0, feldspar mineral impurities and layered aluminosilicate mineral particle impurities are floated out, and then the goal of purifying quartz sand is achieved.

[0007] In addition, some patent technologies also report flotation separation methods for feldspar, mica, and quartz, respectively. However, these flotation separation methods are often only effective for part of the aluminosilicate minerals, and lack research on other aluminosilicate minerals such as kaolinite and zeolite. SUMMARY

[0008] Aiming at the above technical problems and the deficiencies in the field, the present application provides a method for separating aluminosilicate minerals and purifying quartz sand under neutral conditions and its application. The present application has simple and efficient operation steps: the quartz raw sand can be obtained by a series of pretreatments on the quartz-containing raw ore, and the quartz reverse flotation is carried out under neutral and mild conditions, the quartz depressant is added preferentially to inhibit the floating of quartz; then the aluminosilicate mineral collector is added to realize the efficient separation of quartz and aluminosilicate minerals; in order to make up for the weak foaming problem of the aluminosilicate mineral collector, a foaming agent, preferably pine oil, is added to prolong the foaming time of the flotation. The content of aluminum oxide in the quartz sand obtained by reverse flotation is reduced to below 100 ppm.

[0009] A method for separating aluminosilicate minerals and purifying quartz sand under neutral conditions, which adopts one or more reverse flotation operations, the reverse flotation operation comprising:

[0010] The quartz depressant is added to the quartz raw sand slurry or the low-aluminum content fine quartz sand slurry obtained by the last reverse flotation operation, and mixed evenly; then the aluminosilicate mineral collector is added and mixed evenly; then the foaming agent is added under the condition of air agitation to carry out quartz reverse flotation, and stirring and bubble scraping are maintained during the process; after the reverse flotation is completed, the remaining slurry is washed to obtain low-aluminum content fine quartz sand.

[0011] The quartz raw sand contains quartz and aluminosilicate minerals.

[0012] In the present application, the aluminosilicate minerals can include one or more of feldspar, kaolin, zeolite, garnet, kyanite, sillimanite, and mica.

[0013] The particle size of the quartz raw sand in the quartz raw sand slurry can be 60-100 mesh.

[0014] The mass concentration of the quartz raw sand in the quartz raw sand slurry can be 45%-55%.

[0015] The mass concentration of the low-aluminum content fine quartz sand in the low-aluminum content fine quartz sand slurry can be 45%-55%.

[0016] The quartz raw sand can be obtained by pretreating the raw ore, and the pretreatment can include: sequentially crushing, grinding, screening, magnetic separation, water washing, acid washing, and drying the raw ore.

[0017] In some embodiments, the crushing can include crushing the raw ore into small ore of 1-5 centimeters.

[0018] In some embodiments, the acid used in the acid washing can be 0.1wt%-1wt% (for example, 0.5wt%) dilute sulfuric acid.

[0019] In some embodiments, the mass content of quartz in the raw ore is not less than 50%, and the mass content of aluminosilicate minerals is not higher than 50%.

[0020] In the reverse flotation operation, the pH of the ore pulp can be maintained at 6.5-7.5.

[0021] In the reverse flotation operation, no additional acid or alkali can be added.

[0022] In the reverse flotation operation, the temperature of the ore pulp can be maintained at 20-30℃.

[0023] The addition sequence of the reagents in the reverse flotation operation is crucial. In order to ensure the effective separation of quartz and aluminosilicate minerals, a quartz depressant needs to be added before the collector, so as to reduce the interaction between the collector and quartz, and maximize the flotation separation of quartz and aluminosilicate minerals.

[0024] The quartz depressant preferably includes one or both of sodium fluorosilicate and ammonium fluorosilicate.

[0025] The mass ratio of the added mass of the quartz depressant to the mass of solids in the quartz raw ore pulp can be 15-20 g:1 t.

[0026] The aluminosilicate mineral collector preferably includes one or more sulfonate amphoteric ion collectors having the structure shown below:

[0027] ,

[0028] wherein n is selected from 6-16, such as 6, 8, 10, 12, 14, 16, etc.

[0029] The aluminosilicate mineral collector of the present application preferably uses an amphoteric compound containing a sulfonate group and a quaternary ammonium salt structure. The structure of the amphoteric compound contains an anion group sulfonate ion, a positively charged quaternary ammonium salt structure, and a hydrophobic long-chain alkane. The sulfonate ion and the quaternary ammonium salt structure are connected by three methylene groups, and the length of the long-chain alkane is eight carbon structures to eighteen carbon structures.

[0030] Under neutral conditions, the surfaces of quartz and aluminosilicate minerals both carry negative charges. The positively charged nitrogen ions in the amphoteric compound collector used in the present application are adsorbed on the surfaces of the two ores through electrostatic interaction. The aluminum ions in the aluminosilicate minerals are adsorbed on the sulfonate groups in the collector through coordination interaction, and the adsorption of quartz on the collector is weak due to the lack of aluminum ions, thereby realizing selective adsorption of the collector on the aluminosilicate minerals and high-selectivity flotation separation of the aluminosilicate minerals and quartz.

[0031] Further, the aluminosilicate mineral collector preferably includes one or more of 3-(N,N-dimethyldodecylammonium)propane sulfonate (CAS No.: 14933-08-5), hexadecyl sulfobetaine (CAS No.: 2281-11-0), 3-sulfopropyl tetradecyldimethylammonium betaine (CAS No.: 14933-09-6), 3-(N,N-dimethyloctylammonium) propane-1-sulfonic acid inner salt (CAS No.: 15178-76-4), 3-(decyldimethylammonio) propane-1-sulfonate (CAS No.: 15163-36-7), 3-(dimethyl(octadecyl)ammonio) propane-1-sulfonic acid inner salt (CAS No.: 13177-41-8).

[0032] In some preferred examples, the ratio of the added mass of the aluminosilicate mineral collector to the mass of solids in the quartz raw sand slurry is 20-30 g:1 t. Too little collector added will result in poor separation of the aluminosilicate minerals and quartz, affecting the grade of the quartz, while too much collector added will cause some of the quartz sand to float with the aluminosilicate minerals, affecting the recovery rate of the quartz.

[0033] In the present application, a frother is required to extend the flotation time and improve the stability of the froth. The frother preferably includes pinolene oil. The ratio of the added mass of the frother to the mass of solids in the quartz raw sand slurry can be 10-20 g:1 t.

[0034] In the method of the present application, the purity of SiO2 in the low-aluminum-content fine quartz sand obtained by one or more reverse flotation operations is ≥99.9%, and the content of Al2O3 is ≤100 ppm. Multiple reverse flotation operations can further improve the purity of the product quartz sand.

[0035] The present application also provides the use of the method in separating aluminosilicate minerals and purifying quartz sand.

[0036] Compared with the prior art, the present application has the following beneficial effects:

[0037] (1) The present application uses reverse flotation strategy for ores with high quartz content, which is superior to positive flotation strategy in terms of reducing the amount of reagents used and improving the separation effect of flotation.

[0038] (2) The aluminosilicate mineral collector preferably used in the present application is a zwitterionic collector with a sulfonate group and a quaternary ammonium salt structure. The collector is adsorbed on different sites of the aluminosilicate mineral through the synergistic action of the positively charged nitrogen ion and the sulfonate anion, and the adsorption is stronger and the adsorption amount is larger. Therefore, the collecting ability of the collector for aluminosilicate minerals is greater than that of traditional single or mixed collectors, and the reverse flotation separation effect of the collector for quartz and aluminosilicate minerals is superior to the flotation effect of single or mixed collectors.

[0039] (3) The collector used in the application has two polar groups and one hydrophobic long chain, and has good hydrophilicity and hydrophobicity, which overcomes the problem of poor water solubility of traditional collectors with a single polar group. Compared with other collectors, the collector used in the application has stronger capturing ability for aluminum elements and higher sensitivity, and has good capturing ability for a small amount of aluminum elements exposed on the surface of the crystal, thereby exhibiting better separation effect on the flotation separation of quartz and aluminosilicate minerals.

[0040] (4) The reverse flotation process of the application is carried out under neutral conditions, avoiding the use of traditional strong acid and strong base, thereby reducing the harm of the purification process to production equipment, ecological environment and operating personnel. DETAILED DESCRIPTION

[0041] The application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not to limit the scope of the application. The operation methods not specified in the following examples are usually carried out according to conventional conditions or according to the conditions recommended by the manufacturer. Example 1

[0042] 1. Mineral raw material:

[0043] The mass content of quartz in the raw ore is 50.23%, the mass content of feldspar is 28.40%, the mass content of kaolin is 14.78%, and the mass content of other aluminosilicate minerals such as zeolite, garnet, kyanite and sillimanite is 4.32%. Phase analysis shows that the ore mainly contains quartz, feldspar and kaolin.

[0044] 2. Flotation reagents and operating conditions:

[0045] Pretreatment process: the above raw ore is crushed into small ore of 1-5 centimeters by a crusher, and the small ore is put into a wet mill for grinding and sieved into 60-100 mesh raw sand; then the sieved raw sand is poured into a magnetic separator to remove magnetic impurities; the quartz sand after magnetic separation is cleaned with water in a scrubbing machine, and after water cleaning, 0.5wt% dilute sulfuric acid is used to clean the impurities on the surface of the sand, and then vacuum drying machine is used for drying treatment.

[0046] The pre-processed raw sand is poured into a flotation machine, and the raw sand preliminarily purified by stirring and rinsing with warm water at 20-30°C is prepared into raw sand slurry with a mass concentration of 45%-55% by mixing; 20 g / t (t is based on the solid mass in the raw sand slurry, and the same below) of sodium fluosilicate, a quartz depressant, is added to the slurry and stirred for 20 minutes, followed by the addition of 20 g / t (t is based on the solid mass in the raw sand slurry, and the same below) of 3-(N,N-dimethyl dodecyl ammonium) propane sulfonate (CAS No. 14933-08-5), an aluminosilicate mineral collector, and stirring for 30 minutes; under the condition of air agitation, 10 g / t (t is based on the solid mass in the raw sand slurry, and the same below) of pine oil, a frother, is added to the slurry, and the quartz reverse flotation is performed, with stirring and froth scraping during the 30-minute flotation; after the flotation, the obtained quartz sand is rinsed with deionized water for two to three times to wash away the residual reagents on the surface of the minerals, and the above process is repeated once to obtain high-quality quartz sand. The pH of the slurry in the reverse flotation process is kept at 6.5-7.5.

[0047] The test results show that the quartz mineral can be effectively recovered according to the above process parameters and reagent conditions, with a recovery rate of 83.25%, and the product quartz sand with a grade (purity) of 99.95% and an aluminosilicate mineral (alumina) content reduced to below 100 ppm. Example 2

[0048] 1. Mineral raw material:

[0049] The mass content of quartz in the raw ore is 64.23%, the mass content of feldspar is 16.22%, the mass content of kaolin is 7.78%, the mass content of mica is 4.94%, and the mass content of other aluminosilicate minerals, zeolite, garnet, kyanite, and sillimanite, is 3.86%; the phase analysis shows that the ore mainly contains quartz, feldspar, kaolin, and mica.

[0050] 2. Flotation reagents and operating conditions:

[0051] The pre-treatment process is the same as that in Example 1;

[0052] The reverse flotation process: the raw sand obtained by the pretreatment is poured into the flotation machine, and the preliminarily purified raw sand is stirred and rinsed once with warm water at 20-30°C, and then the raw sand is prepared into a raw sand slurry with a mass concentration of 45%-55%; the quartz depressor ammonium fluosilicate 20 g / t is added into the slurry, and stirred for 20 minutes, then the aluminosilicate mineral collector 3-(dimethyl(octadecyl)ammonium) propane-1-sulfonate (CAS No.: 13177-41-8) 30 g / t is continuously added, and stirred for 30 minutes; under the condition of air agitation, the frother pinolite oil 10 g / t is further added into the slurry, and the quartz reverse flotation is carried out on the ore, and the flotation is carried out for 30 minutes, during which the stirring and scraping of bubbles are carried out, after the flotation is completed, the obtained quartz sand is rinsed two to three times with deionized water to wash the residual reagents on the surface of the minerals, and the above process is repeated once to obtain high-quality quartz sand. The pH of the slurry in the reverse flotation process is always kept at 6.5-7.5.

[0053] The test results show that the quartz mineral can be effectively recovered according to the above process parameters and reagent conditions, the recovery rate is 80.11%, and the product quartz sand with a grade (purity) of 99.90% is obtained, and the content of aluminosilicate minerals (aluminum oxide) is reduced to below 100 ppm. Example 3

[0054] 1. Mineral raw material:

[0055] The mass content of quartz in the raw ore is 78.19%, the mass content of feldspar is 8.26%, the mass content of garnet is 7.78%, and the mass content of other aluminosilicate minerals kaolin, zeolite, kyanite, and sillimanite is 5.04%, and the phase analysis shows that the ore mainly contains quartz, feldspar, and garnet.

[0056] 2. Flotation reagents and operating conditions:

[0057] The pretreatment process is the same as that in Example 1;

[0058] The reverse flotation process: the raw sand obtained by the pretreatment is poured into the flotation machine, and the preliminarily purified raw sand is stirred and rinsed once with warm water at 20-30°C, and then the raw sand is prepared into a raw sand slurry with a mass concentration of 45%-55%; the quartz depressor ammonium fluosilicate 20 g / t is added into the slurry, and stirred for 20 minutes, then the aluminosilicate mineral collector 3-(dimethyl(octadecyl)ammonium) propane-1-sulfonate (CAS No.: 13177-41-8) 30 g / t is continuously added, and stirred for 30 minutes; under the condition of air agitation, the frother pinolite oil 10 g / t is further added into the slurry, and the quartz reverse flotation is carried out on the ore, and the flotation is carried out for 30 minutes, during which the stirring and scraping of bubbles are carried out, after the flotation is completed, the obtained quartz sand is rinsed two to three times with deionized water to wash the residual reagents on the surface of the minerals, and the above process is repeated once to obtain high-quality quartz sand. The pH of the slurry in the reverse flotation process is always kept at 6.5-7.5.

[0059] The test results show that under the above process parameters and reagent conditions, the quartz mineral can be effectively recovered, the recovery rate is 82.21%, and the product quartz sand with a grade (purity) of 99.92% is obtained, and the content of aluminum silicate mineral (aluminum oxide) is reduced to below 100 ppm. Comparative Example 1

[0060] The difference between this comparative example and Example 1 is only that no quartz depressant sodium fluosilicate is added in the flotation reagent, and the rest is the same.

[0061] The test results show that without adding the quartz depressant sodium fluosilicate, not only the recovery rate of quartz is significantly reduced, which is 61.29%, but also the grade of quartz is slightly reduced, and the product quartz sand with a grade of 99.93% is obtained, and the content of aluminum silicate mineral (aluminum oxide) is reduced to below 100 ppm. Comparative Example 2

[0062] The difference between this comparative example and Example 1 is only that the quartz depressant added in the flotation reagent is water glass 20 g / t (t is based on the solid mass in the original sand ore slurry), and the rest is the same.

[0063] The test results show that the replaced quartz depressant water glass has poor effect on inhibiting the floating of quartz under the neutral conditions of the present application, the recovery rate of quartz is 71.68%, which is lower than that when sodium fluosilicate is used as the depressant, and only the product quartz sand with a grade of 99.91% can be obtained, and the content of aluminum silicate mineral (aluminum oxide) is reduced to below 100 ppm. Comparative Example 3

[0064] The difference between this comparative example and Example 1 is only that the collector is replaced by trimethyl dodecyl ammonium chloride 30 g / t (t is based on the solid mass in the original sand ore slurry), and the rest is the same.

[0065] The test results show that the replaced collector trimethyl dodecyl ammonium chloride cannot effectively separate quartz and aluminum silicate mineral under the neutral conditions of the present application, the recovery rate of quartz is 87.32%, the grade is only 85.71%, and the content of aluminum silicate mineral (aluminum oxide) exceeds 1%, and the flotation cannot be effectively carried out. Comparative Example 4

[0066] The difference between this comparative example and Example 1 is only that the collector is replaced by a mixed collector: a mixture of trimethyl dodecyl ammonium chloride and sodium dodecyl sulfonate (according to the mass ratio 1:1), 30 g / t (t is based on the solid mass in the original sand ore slurry), and the rest is the same.

[0067] The test results show that the mixed collector after replacement, trimethyl dodecyl ammonium chloride and sodium dodecyl sulfonate, under the neutral condition in the application, causes part of the aluminosilicate minerals to be unable to float, and thus the quartz and the aluminosilicate minerals cannot be effectively separated, wherein the quartz recovery rate is 94.39%, the grade is only 79.12%, and the content of the aluminosilicate minerals (aluminum oxide) is more than 2%, and the flotation cannot be effectively performed.

[0068] Furthermore, it is to be understood that even though numerous characteristics and embodiments of the application have been set forth in the foregoing description, many modifications and / or changes of the embodiments of the application in addition to those described above are possible. Such modifications and changes are also intended to fall within the scope of the application as defined in the appended claims.

Claims

1. A method for separating aluminosilicate minerals and purifying quartz sand under neutral conditions, characterized by, The one or more reverse flotation operations comprise: adding a quartz depressor into the quartz raw sand slurry or the low-aluminum-content fine quartz sand slurry obtained from the previous reverse flotation operation, and mixing; then adding an aluminosilicate mineral collector, and mixing; and then adding a frother under the condition of air agitation, and performing quartz reverse flotation, during which agitation is maintained and froth is scraped; after the reverse flotation is completed, the remaining slurry is washed to obtain the low-aluminum-content fine quartz sand; the quartz depressor is one or both of sodium fluorosilicate and ammonium fluorosilicate; the mass ratio of the quartz depressor to the solid mass in the quartz raw sand slurry is 15-20 g:1 t; the aluminosilicate mineral collector comprises one or more sulfonate amphoteric ion collectors having the structure shown in the following formula: wherein n is selected from 6-16; the mass ratio of the aluminosilicate mineral collector to the solid mass in the quartz raw sand slurry is 20-30 g:1 t; the purity of SiO2 in the low-aluminum-content fine quartz sand obtained from the one or more reverse flotation operations is ≥99.9%, and the content of Al2O3 is ≤100 ppm.

2. The method of claim 1, wherein, the quartz raw sand contains quartz and aluminosilicate minerals; the particle size of the quartz raw sand in the quartz raw sand slurry is 60-100 mesh; the mass concentration of the quartz raw sand in the quartz raw sand slurry is 45%-55%; the mass concentration of the low-aluminum-content fine quartz sand in the low-aluminum-content fine quartz sand slurry is 45%-55%; the quartz raw sand is obtained through raw ore pretreatment, and the pretreatment comprises: sequentially performing crushing, grinding, screening, magnetic separation, water washing, acid washing, and drying on the raw ore; the crushing comprises crushing the raw ore into small ore pieces of 1-5 centimeters; the acid used in the acid washing is dilute sulfuric acid with a concentration of 0.1wt%-1wt%; the mass content of quartz in the raw ore is not less than 50%, and the mass content of aluminosilicate minerals is not higher than 50%; the aluminosilicate minerals comprise one or more of feldspar, kaolin, zeolite, garnet, kyanite, sillimanite, and mica.

3. The method of claim 1, wherein, in the reverse flotation operation: the pH of the slurry is maintained at 6.5-7.5; no additional acid or alkali is added; the temperature of the slurry is maintained at 20-30℃.

4. The method of claim 1, wherein, the aluminosilicate mineral collector comprises one or more of 3-(N,N-dimethyldodecylammonium) propane sulfonate, hexadecyl sulfobetaine, 3-sulfopropyl tetradecyl dimethyl betaine, 3-(N,N-dimethyloctylammonium) propane-1-sulfonate inner salt, 3-(decyldimethylammonium) propane-1-sulfonate, and 3-(dimethyl(octadecyl)ammonium) propane-1-sulfonate inner salt.

5. The method of claim 1, wherein, the frother comprises pine oil; the mass ratio of the frother to the solid mass in the quartz raw sand slurry is 10-20 g:1 t.

6. The method according to any one of claims 1-5 for separating aluminosilicate minerals and purifying quartz sand.

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