Acid pickling process for preparing high-purity quartz sand

Abstract

The invention discloses an acid pickling process for preparing high-purity quartz sand, which belongs to the technical field of purification production of high-purity quartz sand, and comprises the steps of ore selection, surface cleaning, jaw breaking, hammer breaking, screening, magnetic separation, flotation impurity removal, high-temperature microwave gas-liquid inclusion removal, acid leaching process, drying magnetic separation and the like. Sulfuric acid can react with most metals, most sulfide minerals are converted into corresponding high-valence metal sulfate, alkali metal content is reduced by diluting and washing away, impurities which are not completely removed in the production process or introduced in the production process can be oxidized and removed, subsequent operation pressure is reduced, production water is reduced, and finished product output is improved. And compared with the conventional process, the ICP inductively coupled plasma emission chromatograph has no influence on element detection of the acid-washed sand.

Description

Technical Field

[0001] The invention belongs to the technical field of high-purity quartz sand production and relates to a pickling process for preparing high-purity quartz sand. Background Art

[0002] High-purity quartz sand is a national strategic product. Its SiO2 content is generally higher than 99.99%. It is widely used in high-tech industries such as integrated circuits, medicine, military industry, aerospace, optical communications, laser, and electronics industry, especially high-end optical electronic engineering. After physical purification, almost all mineral impurities existing in monomers can be removed, and the content of impurity elements after impurity removal is at a low level. Physical purification cannot remove gas-liquid inclusions and isomorphous impurities inside the lattice, which are the main sources of impurities. These impurities are the key factors restricting the preparation of high-purity quartz products, so chemical deep purification is required. Acid treatment is a very important purification method in chemical purification. Acid treatment removes impurities that exist on the surface of quartz sand particles in the form of inclusions or embedded in the particles. There are also a small amount of impurity minerals in the grain boundaries, microcracks and crystals. The acid treatment method is mainly to remove these impurities. Among them, the acid leaching method is the most widely used, and a mixed solution of hydrofluoric acid, sulfuric acid, hydrochloric acid and nitric acid is often used to purify quartz sand. However, nitric acid is used in large quantities during acid leaching, and the liquid-to-solid ratio is usually 3:1. Large amounts of acid not only pollute the environment, but also require more clean water for subsequent cleaning. Therefore, it is necessary to adopt an environmentally friendly acid leaching process. Summary of the invention

[0003] In order to fill the gap in the prior art, the present invention provides a pickling process for preparing high-purity quartz sand to overcome the shortcomings of the prior art.

[0004] The technical solution of the present invention: A pickling process for preparing high-purity quartz sand comprises the following steps: S1: Select high-grade quartz ore and wash the surface of the ore to remove non-mineral impurities such as surface soil and other attachments; S2: After the jaw crusher and hammer crusher process, the large ore is crushed into small ore, and then crushed and screened to collect 50-200 mesh particles as crushed semi-finished raw materials; S3: Magnetic separation is performed on the crushed semi-finished raw materials through a magnetic separator to remove magnetic substances; S4: Flotation removes impurities from sand, including iron impurities and ore-associated impurities such as feldspar and mica; S5: releasing the gas-liquid inclusions and isomorphous impurities inside the crystal lattice by high temperature and microwave heating, followed by water quenching; S6: adding mixed acid to pickle the quartz sand after water quenching, wherein the mixed acid is prepared by mixing hydrofluoric acid, hydrochloric acid, sulfuric acid and water in a molar ratio of 1-3:2-4:0.5-1.5:4-6, and adding the mixed acid to the pickling reactor containing the quartz sand after water quenching and fully shaking it, wherein the solid-liquid ratio of the quartz sand to the mixed acid is 2-4:1, and the temperature is controlled at 140-160°C, and the acid leaching reaction is carried out, and the mixture is fully shaken once every 1 hour. After pickling for 18-24 hours, the quartz sand is drained, and ultrapure water is added to clean the sand containing residual acid solution, and then dried; S7: The dried quartz sand is subjected to 4-8 times of magnetic separation, and the discharge temperature of the magnetic separation is ≤50°C. After the magnetic separation is completed, high-purity quartz sand is obtained.

[0005] Furthermore, the quartz ore in S1 is vein quartz or pegmatite.

[0006] Furthermore, the flotation process in S4 is to first add water to the flotation machine to wash and drain the crushed semi-finished raw materials after magnetic separation; then add sodium hydroxide as a pH adjuster and use it in combination with QS flotation collector to perform rough flotation to remove impurities, including associated minerals such as feldspar and mica and non-magnetic associated minerals; then add sulfuric acid as a pH adjuster and use it in combination with 608 anion collector and kerosene frother to perform fine flotation to remove iron impurities; finally, add sulfuric acid as an adjuster and use it in combination with dodecylamine cationic collector to perform fine flotation to remove impurities associated with ores such as feldspar and mica.

[0007] Furthermore, in S7, a microwave heating rotary kiln is used to heat the quartz sand to a high temperature of 600-1300° C., and the selective heating characteristics of microwaves are utilized to release gas-liquid inclusions and isomorphous impurities inside the lattice, and then water quenching is performed.

[0008] Furthermore, in S6, the acid is prepared in a molar ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: water = 2:3:1:5.

[0009] Furthermore, the solid-to-liquid ratio of quartz sand and mixed acid in S6 is 3:1. Furthermore, the pickling time in S6 is 20 hours.

[0010] Furthermore, the number of magnetic separations in S7 is 6 times, and the magnetic separation temperature is 45°C.

[0011] The beneficial effects of the present invention are: The present invention converts most of the sulfide minerals into corresponding high-valent metal sulfates by adding sulfuric acid during the pickling process, and reduces the alkali metal content by diluting and washing away. At the same time, the oxidation impurity black spots can be effectively degraded, the water used in the production process can be reduced, the production capacity and finished product output of the subsequent operation can be improved, and the finished product elements have no effect, which is conducive to the production of higher-quality high-purity quartz sand. The purity of the high-purity quartz sand purified by this process is higher than the 4N8 level and reaches the 4N9 level. The purification effect is outstanding, so as to better meet customer requirements and market demands. The solid-liquid ratio of the quartz sand and the mixed acid of the present invention is 3:1, the amount of the mixed acid is small, the amount of water used for subsequent cleaning is small, and it is environmentally friendly. DETAILED DESCRIPTION

[0012] The specific embodiments of the present invention are described in detail below. Example 1

[0013] The production of quartz sand coarse material includes the following steps: S1: Select high-grade vein quartz or pegmatite or other quartz ore, and use a cleaning machine to clean the surface of the ore to remove non-mineral impurities such as surface soil and other attachments; S2: After the jaw crusher and hammer crusher process, the large ore is crushed into small ore, and then crushed and screened to collect 50-200 mesh particles as crushed semi-finished raw materials; S3: Magnetic separation is performed on the crushed semi-finished raw materials through a magnetic separator to remove magnetic substances; S4: Flotation to remove impurities: First, add water to the flotation machine to wash and drain the crushed semi-finished raw materials after magnetic separation; then add sodium hydroxide as a pH adjuster and use it with QS flotation collector to perform rough flotation to remove impurities, including associated minerals such as feldspar and mica and non-magnetic associated minerals; then add sulfuric acid as a pH adjuster and use it with 608 anion collector and kerosene frother to perform fine flotation to remove iron impurities; finally, add sulfuric acid as an adjuster and use it with dodecylamine cationic collector to perform fine flotation to remove impurities associated with feldspar, mica and other minerals; S5: Using microwave heating rotary kiln, heat the quartz sand to 600-1300℃, and use microwave selective heating characteristics to remove gas-liquid inclusions inside the quartz sand, so that impurities therein are released. This step is to release gas-liquid inclusions and isomorphous impurities inside the lattice by high temperature and microwave heating, and then perform water quenching.

[0014] High purity quartz sand acid leaching process S6: prepare acid with a molar ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: water = 2:3:1:5, add mixed acid to pickle the quartz sand after water quenching, shake the mixed acid and add it to the pickling reactor containing the quartz sand after water quenching and shake it thoroughly, the solid-liquid ratio of quartz sand and mixed acid is 3:1, the temperature is controlled at 150°C, and acid leaching reaction is carried out, shaking it thoroughly every 1 hour, after pickling for 20 hours, drain the quartz sand, add ultrapure water to clean the sand containing residual acid, and then dry it; S7: The dried quartz sand is subjected to 6 magnetic separations, and the discharge temperature of the magnetic separation is controlled at 45° C. After the magnetic separation is completed, high-purity quartz sand is obtained.

[0015] Test: The pickled and dried samples were tested for elements in the pickled quartz sand using ICP inductively coupled plasma emission chromatograph. The results showed that the mixed acid had a good leaching effect and had a good removal effect on the impurities of elements such as Na, K, and Fe in the ore.

[0016] The magnetic separation process can effectively remove substances such as Na, K, and Fe from the sand, and the purity level of the prepared high-purity quartz sand exceeds 4N8 level and reaches 4N9 level. Example 2

[0017] High purity quartz sand acid leaching process S6: prepare acid with a molar ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: water = 3:4:1.5:6, add mixed acid to pickle the quartz sand after water quenching, shake the mixed acid and add it to the pickling reactor containing the quartz sand after water quenching and shake it thoroughly, the solid-liquid ratio of quartz sand and mixed acid is 4:1, the temperature is controlled at 160°C, and the acid leaching reaction is carried out, and the mixture is shaken thoroughly every 1 hour. After pickling for 24 hours, the quartz sand is drained and ultrapure water is added to clean the sand containing residual acid solution, and then dried; S7: The dried quartz sand is subjected to 4 magnetic separations at a discharge temperature of 50° C., and high-purity quartz sand is obtained after the magnetic separations are completed.

[0018] Test: The pickled and dried samples were tested for elements in the pickled quartz sand using ICP inductively coupled plasma emission chromatograph. The results showed that the mixed acid had a good leaching effect and had a good removal effect on the impurities of elements such as Na, K, and Fe in the ore.

[0019] The magnetic separation process can effectively remove substances such as Na, K, and Fe from the sand, and the purity level of the prepared high-purity quartz sand exceeds 4N8 level and reaches 4N9 level. Example 3

[0020] High purity quartz sand acid leaching process S6: prepare acid with a molar ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: water = 1:2:0.5:4, add mixed acid to pickle the quartz sand after water quenching, shake the mixed acid and add it to the pickling reactor containing the quartz sand after water quenching and shake it thoroughly, the solid-liquid ratio of quartz sand and mixed acid is 2:1, the temperature is controlled at 140°C, and the acid leaching reaction is carried out, and the mixture is shaken thoroughly every 1 hour. After pickling for 18 hours, the quartz sand is drained and ultrapure water is added to clean the sand containing residual acid solution, and then dried; S7: The dried quartz sand is subjected to 8 magnetic separations, and the discharge temperature of the magnetic separation is room temperature. After the magnetic separation is completed, high-purity quartz sand is obtained.

[0021] Test: The pickled and dried samples were tested for elements in the pickled quartz sand using ICP inductively coupled plasma emission chromatograph. The results showed that the mixed acid had a good leaching effect and had a good removal effect on the impurities of elements such as Na, K, and Fe in the ore.

[0022] The magnetic separation process can effectively remove substances such as Na, K, and Fe from the sand, and the purity level of the prepared high-purity quartz sand exceeds 4N8 level and reaches 4N9 level.

[0023] The present invention adds a certain proportion of sulfuric acid during the pickling process. The sulfuric acid can react with most metals, convert most of the sulfide minerals into corresponding high-valent metal sulfates, and wash them away through dilution, thereby reducing the alkali metal content. In addition, impurities that are not completely removed during the production process or introduced during the production can be oxidized and removed, thereby reducing the pressure of subsequent operations, reducing production water, and increasing the output of finished products. In addition, compared with conventional processes, the detection of elements in sand after pickling by ICP inductively coupled plasma emission chromatograph has basically no effect.

[0024] The above shows and describes the basic principles, main features and advantages of the present invention. The present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A pickling process for preparing high-purity quartz sand, characterized in that: The following steps are involved: S1: Select high-grade quartz ore and wash the surface of the ore to remove non-mineral impurities such as surface soil and other attachments; S2: After the jaw crusher and hammer crusher process, the large ore is crushed into small ore, and then crushed and screened to collect 50-200 mesh particles as crushed semi-finished raw materials; S3: Magnetic separation is performed on the crushed semi-finished raw materials through a magnetic separator to remove magnetic substances; S4: Flotation removes impurities from sand, including iron impurities and ore-associated impurities such as feldspar and mica; S5: releasing the gas-liquid inclusions and isomorphous impurities inside the crystal lattice by high temperature and microwave heating, followed by water quenching; S6: adding mixed acid to pickle the quartz sand after water quenching, wherein the mixed acid is prepared by mixing hydrofluoric acid, hydrochloric acid, sulfuric acid and water in a molar ratio of 1-3:2-4:0.5-1.5:4-6, and adding the mixed acid to the pickling reactor containing the quartz sand after water quenching and fully shaking it, wherein the solid-liquid ratio of the quartz sand to the mixed acid is 2-4:1, and the temperature is controlled at 140-160°C, and the acid leaching reaction is carried out, and the mixture is fully shaken once every 1 hour. After pickling for 18-24 hours, the quartz sand is drained, and ultrapure water is added to clean the sand containing residual acid solution, and then dried; S7: The dried quartz sand is subjected to 4-8 times of magnetic separation, and the discharge temperature of the magnetic separation is ≤50°C. After the magnetic separation, high-purity quartz sand is obtained.

2. A pickling process for preparing high-purity quartz sand as claimed in claim 1, characterized in that: The quartz ore in S1 is vein quartz or pegmatite.

3. A pickling process for preparing high-purity quartz sand as claimed in claim 1, characterized in that: The flotation process in S4 is to first add water to the flotation machine to wash and drain the crushed semi-finished raw materials after magnetic separation; then add sodium hydroxide as a pH adjuster and use it in combination with QS flotation collector to perform rough flotation to remove impurities, including associated minerals such as feldspar and mica and non-magnetic associated minerals; then add sulfuric acid as a pH adjuster and use it in combination with 608 anion collector and kerosene frother to perform fine flotation to remove iron impurities; finally, add sulfuric acid as an adjuster and use it in combination with dodecylamine cationic collector to perform fine flotation to remove impurities associated with ores such as feldspar and mica.

4. A pickling process for preparing high-purity quartz sand as claimed in claim 1, characterized in that: In the step S7, a microwave heating rotary kiln is used to heat the quartz sand to a high temperature of 600-1300° C., and the selective heating characteristics of microwaves are utilized to release gas-liquid inclusions and isomorphous impurities inside the lattice, and then water quenching is performed.

5. The pickling process for preparing high-purity quartz sand according to claim 1, characterized in that: In the S6, the acid is prepared in a molar ratio of hydrofluoric acid: hydrochloric acid: sulfuric acid: water = 2:3:1:

5.

6. A pickling process for preparing high-purity quartz sand according to claim 1, characterized in that: The solid-to-liquid ratio of quartz sand to mixed acid in the S6 is 3:

1.

7. The pickling process for preparing high-purity quartz sand according to claim 1, characterized in that: The pickling time in S6 is 20 hours.

8. The pickling process for preparing high-purity quartz sand according to claim 1, characterized in that: The number of magnetic separations in S7 is 6, and the magnetic separation temperature is 45°C.