Method for efficiently separating and preparing 4N quartz by using high-silicon iron ore waste

Abstract

This invention provides a novel method for the efficient separation and preparation of 4N quartz from high-silicon iron ore waste. This method employs an innovative multi-stage strong magnetic separation and a two-stage ternary acid washing process, increasing the iron concentrate grade to 60% while simultaneously producing 99.99% high-purity quartz. Compared to existing technologies, this invention not only optimizes the process flow but also significantly reduces environmental pollution and operating costs, improves the utilization efficiency of useful components in high-silicon iron ore waste, and effectively addresses the challenge of high-quality quartz resource shortages. Particularly in the sulfuric acid-phosphoric acid-hydrofluoric acid ternary acid washing stage, this technology demonstrates significant advantages in purification effect, environmental performance, and cost control, providing a more environmentally friendly and economical solution for the resource utilization of high-silicon iron ore waste.

Description

Technical Field

[0001] This invention belongs to the field of secondary utilization of mineral resources and relates to a method for efficiently separating and preparing 4N quartz from high-silicon iron ore waste. Background Technology

[0002] High-silicon iron ore waste is a byproduct generated during iron ore refining, mainly composed of quartz, silicate minerals, and hematite. Rich in silicon, it possesses certain economic value. However, traditional utilization methods suffer from low utilization rates and environmental pollution. Therefore, developing a new method for the resource utilization of high-silicon iron ore waste is of great significance. In modern industrial production, steel is a crucial material widely used in casting, construction, aerospace, and other fields. The production process from iron ore to steel generates a large amount of tailings, which are high in silicon and low in iron, possessing potential application value. However, traditional utilization methods suffer from low utilization rates and environmental pollution. Although traditional methods such as magnetized roasting, acid leaching, alkali leaching, and hydrothermal methods have achieved iron recovery and silicon extraction to some extent, these methods typically face problems such as high energy consumption, significant environmental pollution, large equipment investment, and insufficient purity.

[0003] Therefore, developing a method that can both efficiently recover iron and produce high-purity silicon dioxide is of great practical significance for the special resource of high-silicon iron ore waste. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, the purpose of this invention is to provide a method for efficiently separating and preparing 4N quartz from high-silicon iron ore waste. This method can efficiently realize the resource utilization of high-silicon iron ore waste, not only recovering iron from the waste to obtain high-quality iron concentrate, but also separating and recovering silicon concentrate. The silicon concentrate can be used as a raw material to prepare 4N high-purity quartz, and the acid generated during the entire pickling process can be recycled.

[0005] To achieve the above objectives, this invention provides a method for efficiently separating and preparing 4N quartz from high-silicon iron ore waste. This method improves the resource utilization rate of high-silicon iron ore waste and increases the added value of the product.

[0006] This invention discloses a method for efficiently separating and preparing 4N quartz from high-silicon iron ore waste, comprising the following steps:

[0007] (1) Desliming-magnetic separation: First, the high-silicon iron ore waste is deslimed and then subjected to multi-stage magnetic separation. The first stage of strong magnetic separation is 1.8 to 2.1T. After magnetic separation, the first iron concentrate and silicon concentrate are obtained. Then, the first iron concentrate is subjected to the second stage of magnetic separation with a magnetic field strength of 1.5 to 1.6T to obtain the second iron concentrate.

[0008] (2) Leaching under normal pressure: The silica concentrate obtained in step (1) is ball-milled to a predetermined fineness, and leached under normal pressure using a ternary mixed acid. The leached product is washed to neutral and dried to obtain the first high-purity quartz.

[0009] (3) High-temperature hot-press leaching: The first high-purity quartz is ball-milled to a set fineness, and the ball-milled first high-purity quartz is leached by high-temperature hot-press leaching using ternary mixed acid to obtain the acid-washed product.

[0010] (4) Heat treatment: The acid washing product obtained in step (3) is washed until neutral, dried and then heat treated to obtain the second high-purity quartz, which is the 4N quartz product.

[0011] The ternary mixed acid is a mixture of sulfuric acid, phosphoric acid, and hydrofluoric acid in a volume ratio of 1-3:1-3:1.

[0012] In the preferred embodiment, in step (1), a wet high-intensity magnetic separator or a high-gradient magnetic separator is used for magnetic separation.

[0013] In the preferred embodiment, in step (1), the magnetic field strength of the first stage of strong magnetic separation is 1.8–2.1 T, and the slurry-to-ore ratio is 1:5–10. This process optimizes the separation efficiency of iron and silicon, reduces the silicon content in iron concentrate, and provides a purer silicon source for the subsequent preparation of high-purity SiO2.

[0014] In the preferred embodiment, in step (1), the magnetic field strength of the second stage of magnetic separation is 1.2 to 1.6 T, and the slurry-to-ore ratio is 1:5 to 10. The difference in the magnetic separation stage of this invention is that flotation is not required, and the iron concentrate obtained after magnetic separation has a high grade.

[0015] Further preferred, the second stage of magnetic separation involves performing one or more magnetic separations on the first iron concentrate.

[0016] In the preferred embodiment, the atmospheric pressure leaching process in step (2) is as follows: the acid concentration is 9-10 mol / L, the atmospheric pressure leaching time is 5-6 h, the reaction temperature is 90-100 ℃, and the liquid-solid ratio is 4-5:1 (mL:g).

[0017] In the preferred embodiment, in step (2), the drying temperature is 100-105℃ and the drying time is 3-8h. After initial purification, the first high-purity quartz is obtained with a total impurity of 500-900mg / kg, which is a 3N-3N5 high-purity quartz product.

[0018] In the preferred embodiment, in steps (2) and (3), zirconium balls are used as the grinding medium during the ball milling process, and nylon screens are selected as the sieves.

[0019] In the preferred embodiment, the high-temperature hot acid leaching process in step (3) is as follows: the acid concentration is 9-10 mol / L, the leaching time is 5-8 h, the reaction temperature is 180-200 °C, and the liquid-to-solid ratio is 4-5:1 (mL:g). Through hot acid leaching, this purification process significantly improves the purity of SiO2 and reduces the impurity content.

[0020] In the preferred embodiment, in step (3), the pickling equipment used for high-temperature hot-press leaching is a reaction vessel. The reaction vessel used can withstand high temperature and high pressure conditions to ensure leaching efficiency and safety.

[0021] In the preferred embodiment, in step (4), the drying temperature is 100-105℃ and the drying time is 3-8h.

[0022] In the preferred embodiment, the heat treatment process in step (4) is as follows: high temperature treatment at 900-1000℃ in a tubular furnace for 3-5 hours. After primary purification, secondary purification and heat treatment, a second high-purity quartz is obtained, and the total impurities can be reduced to below 100mg / kg, which is the 4N high-purity quartz product.

[0023] In the preferred embodiment, after the waste liquid undergoes evaporation and crystallization treatment, sulfuric acid and hydrofluoric acid are recovered for recycling, which significantly reduces chemical consumption and environmental impact, meets environmental protection requirements, and improves the economy and sustainability of the entire process.

[0024] The preferred method involves multiple rinses with ultrapure water after pickling, and the washing equipment must be made of polytetrafluoroethylene (PTFE), not glass.

[0025] This invention employs a mixed acid of sulfuric acid, phosphoric acid, and hydrofluoric acid. Sulfuric acid, being a strong acid, effectively dissolves metallic impurities such as iron, aluminum, and calcium in quartz, promoting their dissolution and thus improving the purity of the quartz. Hydrofluoric acid is the only acid capable of effectively dissolving silicates, efficiently dissolving silicate minerals in quartz and reducing their content. The presence of hydrofluoric acid significantly improves the leaching efficiency of the pickling process and effectively opens inclusions, releasing impurities and ensuring that the silicon content in the quartz meets high purity requirements. Phosphoric acid can form stable complexes with certain metal ions, such as W, preventing impurities from redepositing during the pickling process. In the mixed acid, phosphoric acid synergizes with the effects of sulfuric acid and hydrofluoric acid, enhancing the pickling effect and further improving the purity of the quartz.

[0026] The innovative aspects of this invention are as follows:

[0027] The raw material of high-silicon iron ore waste has a free SiO2 content of 65-78%, an iron grade of 8-15%, and a -200 mesh content of 10-24%. This precise raw material selection standard is based on a large amount of experimental and practical data and is more conducive to the subsequent preparation of high-purity SiO2 compared with existing technologies.

[0028] The first stage of high-intensity magnetic separation yields a first iron concentrate and a silicon concentrate. The grade of the first iron concentrate is above 40-45%, and the SiO2 content of the silicon concentrate is above 90-95%. This process optimizes the separation efficiency of iron and silicon, reduces the silicon content in the iron concentrate, and provides a purer silicon source for the subsequent preparation of high-purity SiO2. Magnetic separation of the first iron concentrate is then performed with a magnetic field strength of 1.2-1.6T and a pulp-to-ore ratio of 1:5-10 to obtain a second iron concentrate with an iron grade of above 57-60%.

[0029] In the desliming-multi-stage strong magnetic separation process, this invention achieves more efficient iron and silicon separation by precisely controlling the parameters of the multi-stage strong magnetic separation. Compared with existing technologies, this invention uses a wet strong magnetic separator or a high-gradient magnetic separator, and sets the magnetic separation intensity to 1.2T~2.1T. This improvement significantly increases the grade of iron concentrate and silicon concentrate, providing a purer silicon source for subsequent high-purity SiO2 preparation.

[0030] The two-stage acid washing process (initial purification and re-purification) employed in this invention demonstrates significant advantages in purification effect, environmental performance, and cost control. By meticulously controlling acid washing conditions (such as total acid concentration, leaching time, reaction temperature, and liquid-solid ratio), compared with existing technologies, the method of this invention not only achieves higher purity SiO2 but also significantly reduces environmental pollution.

[0031] The heat treatment process in this invention optimizes the process, including drying in a vacuum drying oven and high-temperature treatment in a tube furnace. By precisely controlling the temperature and time, this invention not only removes gas-liquid inclusions and lattice impurities from silicon concentrate, but also ensures the structural stability and high purity of the SiO2 product, which is difficult to achieve with other patented technologies.

[0032] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0033] The method proposed in this invention, by optimizing process parameters and processing flow, not only improves the recovery efficiency of iron and silicon, but also realizes the preparation of 4N high-purity silica, solving the problems existing in traditional methods, and has the characteristics of simplicity, high efficiency, environmental protection and low cost.

[0034] This invention achieves a more efficient separation and purification process through optimization of process parameters and procedures. For example, it employs a wet high-intensity magnetic separator or a high-gradient magnetic separator, with multi-stage magnetic separation intensities ranging from 1.2T to 2.1T, eliminating the need for flotation and thus improving the grade of iron concentrate. During the acid washing process, this invention precisely controls the parameters of the acid washing equipment and the ratio of ternary mixed acid to maximize the removal rate of impurities. Furthermore, after evaporation and crystallization treatment, the sulfuric acid and hydrofluoric acid in the waste liquid can be recycled, significantly reducing chemical consumption and environmental impact, and improving the economy and sustainability of the entire process.

[0035] These innovative process parameters and improvements in processing procedures have enabled the purity of the product of this invention to reach a level unmatched by other patents, ensuring the production of high-purity SiO2 products. Compared with inventions CN 108636591 B and CN116159666A, the purity of quartz has been improved by two grades, and the iron concentrate has also reached 60% iron content. Attached Figure Description

[0036] Figure 1 This is a process flow diagram of the present invention;

[0037] Figure 2 The image shows the XRD pattern of iron concentrate 1 in Example 1. Detailed Implementation

[0038] To better explain the present invention, the following detailed description of the invention is provided in conjunction with the accompanying drawings and specific embodiments. However, the following embodiments do not limit the scope of protection of the claims.

[0039] The composition of high-silicon iron ore waste is as follows: free SiO2 content is 65-78%, iron grade is 8-15%, and -200 mesh content accounts for 10-24%.

[0040] Unless otherwise specified, all chemical reagents used in the following examples are commercially available.

[0041] Example 1

[0042] A method for efficiently separating and preparing 4N quartz from high-silicon iron ore waste includes the following steps:

[0043] (1) Desliming-Magnetic Separation: 100g of high-silicon iron ore waste (low mud content, SiO2 content of 78%, iron grade of 8-10%) was mixed with 500ml of water and subjected to a 1.8T wet high-intensity magnetic separator to obtain silicon concentrate 1 with a grade of 95.45% and iron concentrate 1 with a grade of 58.8%. 100g of iron concentrate 1 was mixed with 500g of water and subjected to a 1.5T wet high-intensity magnetic separator to obtain iron concentrate 2 with a grade of 61.56%.

[0044] (2) Atmospheric pressure leaching: Silica concentrate 1 was ball-milled using a planetary ball mill. Both the milling jar and the milling media were made of 95% zirconium oxide, and the particle size was ground to below -200 mesh. Initial acid washing purification process: Silica concentrate 1 was acid-washed using a ternary acid washing process of sulfuric acid-phosphoric acid-hydrofluoric acid (acid washing conditions: liquid-solid ratio 6:1, acid concentration 8 mol / L, sulfuric acid:phosphoric acid:hydrofluoric acid volume ratio 2:2:1, reaction temperature 100℃, reaction time 3 h). After acid washing, the concentrate was washed with ultrapure water to a neutral pH. It was then dried in a vacuum drying oven at 105℃ for 3 h to obtain high-purity quartz 1 with a purity of over 3N.

[0045] (3) High-temperature hot-press leaching: High-purity quartz 1 was ball-milled using a planetary ball mill. Both the ball milling jar and the ball milling media were made of 95% zirconium oxide. The particle size was ground to below -5000 mesh. The silicon concentrate 1 was hot-pressed and acid-washed using a sulfuric acid-phosphoric acid-hydrofluoric acid ternary acid washing method. The leaching conditions were: total acid concentration of 12 mol / L, sulfuric acid-phosphoric acid-hydrofluoric acid ternary acid ratio of 2:2:1 (volume ratio), high-pressure leaching time of 6 h, reaction temperature of 200 °C, and liquid-solid ratio of 6:1 (mL:g) to obtain the acid-washed product.

[0046] (4) Heat treatment: After acid washing, the product is rinsed with ultrapure water until the pH value is neutral. It is then dried in a vacuum drying oven at 105℃ for 3 hours, followed by high-temperature treatment in a rotary tube furnace at 900℃ for 3 hours. Finally, it is vacuum-packed and sealed to obtain the high-purity quartz product 2. (Refer to...) Figure 1 .

[0047] Table 1 Chemical composition of high-purity quartz 2 in Example 1 (mg / kg)

[0048]

[0049] Example 2

[0050] A method for efficiently separating and preparing 4N quartz from high-silicon iron ore waste includes the following steps:

[0051] (1) Desliming-Magnetic Separation: 100g of raw material was mixed with 500ml of water and subjected to a 1.8T wet high-intensity magnetic separator to obtain silicon concentrate 1 with a grade of 95.45% and iron concentrate 1 with a grade of 58.8%. 100g of iron concentrate 1 was mixed with 500g of water and subjected to a 1.5T wet high-intensity magnetic separator to obtain iron concentrate 2 with a grade of 60.56% and silicon concentrate 2. Ball Milling: Silicon concentrate 1 was ball-milled using a planetary ball mill. The ball mill jar and grinding media were made of 95% zirconia material, and the particle size was ground to below -200 mesh.

[0052] (2) Atmospheric pressure leaching: The silica concentrate 1 was acid-washed using a ternary acid washing system of sulfuric acid, phosphoric acid, and hydrofluoric acid (acid washing conditions: liquid-solid ratio of 5:1, acid concentration of 10 mol / L, sulfuric acid:phosphoric acid:hydrofluoric acid volume ratio of 2:2:1, reaction temperature of 100℃, and reaction time of 3 h). After acid washing, the silica concentrate was washed with ultrapure water to a neutral pH. Then, it was dried in a vacuum drying oven at 105℃ for 3 h to obtain high-purity quartz 1 with a purity of 3N or higher.

[0053] (3) High-temperature hot-press leaching: High-purity quartz 1 was ball-milled using a planetary ball mill. Both the ball milling jar and the ball milling media were made of 95% zirconium oxide. The particle size was ground to below -5000 mesh. The silicon concentrate 1 was hot-pressed and acid-washed using a sulfuric acid-phosphoric acid-hydrofluoric acid ternary acid washing method. The leaching conditions were: total acid concentration of 10 mol / L, sulfuric acid-phosphoric acid-hydrofluoric acid ternary acid ratio of 2:2:1 (volume ratio), high-pressure leaching time of 8 h, reaction temperature of 200 °C, and liquid-solid ratio of 5:1 (mL:g) to obtain the acid-washed product.

[0054] (4) Heat treatment: After pickling, the product is rinsed with ultrapure water to neutral pH. Then it is dried in a vacuum drying oven at 105℃ for 3 hours, then treated in a rotary tube furnace at 1000℃ for 3 hours, and finally vacuum packaged and sealed to obtain the product high-purity quartz 2.

[0055] Table 2 Chemical composition of high-purity quartz 2 in Example 2 (mg / kg)

[0056]

[0057] Example 3

[0058] A method for efficiently separating and preparing 4N quartz from high-silicon iron ore waste includes the following steps:

[0059] (1) Desliming-Magnetic Separation: 100g of raw material was mixed with 500ml of water and subjected to a 1.8T wet high-intensity magnetic separator to obtain silicon concentrate 1 with a grade of 95.45% and iron concentrate 1 with a grade of 58.8%. 100g of iron concentrate 1 was mixed with 500g of water and subjected to a 1.5T wet high-intensity magnetic separator to obtain iron concentrate 2 with a grade of 60.56% and silicon concentrate 2. Ball Milling: Silicon concentrate 1 was ball-milled using a planetary ball mill. The ball mill jar and grinding media were made of 95% zirconia material, and the particle size was ground to below -200 mesh.

[0060] (2) Atmospheric pressure leaching: The silica concentrate 1 was acid-washed using a ternary acid washing system of sulfuric acid, phosphoric acid, and hydrofluoric acid (acid washing conditions: liquid-solid ratio of 5:1, acid concentration of 10 mol / L, sulfuric acid:phosphoric acid:hydrofluoric acid volume ratio of 3:3:1, reaction temperature of 100℃, and reaction time of 3 h). After acid washing, the silica concentrate was washed with ultrapure water to a neutral pH. Then, it was dried in a vacuum drying oven at 105℃ for 3 h to obtain high-purity quartz 1 with a purity of 3N or higher.

[0061] (3) High-temperature hot-press leaching: High-purity quartz 1 was ball-milled using a planetary ball mill. Both the ball milling jar and the ball milling media were made of 95% zirconium oxide. The particle size was ground to below -5000 mesh. The silicon concentrate 1 was hot-pressed and acid-washed using a sulfuric acid-phosphoric acid-hydrofluoric acid ternary acid washing method. The leaching conditions were: total acid concentration of 10 mol / L, sulfuric acid-phosphoric acid-hydrofluoric acid ternary acid ratio of 3:3:1 (volume ratio), high-pressure leaching time of 8 h, reaction temperature of 200 °C, and liquid-solid ratio of 5:1 (mL:g) to obtain the acid-washed product.

[0062] (4) Heat treatment: After pickling, the product is rinsed with ultrapure water to neutral pH. Then it is dried in a vacuum drying oven at 105℃ for 3 hours, then treated in a rotary tube furnace at 1000℃ for 3 hours, and finally vacuum packaged and sealed to obtain the product high-purity quartz 2.

[0063] Table 3 Chemical composition of high-purity quartz 2 in Example 3 (mg / kg)

[0064]

[0065] Comparative Example 1

[0066] In comparison, a mixed acid of sulfuric acid and hydrofluoric acid (volume ratio of 2:1) was added to Comparative Example 1, and the remaining preparation steps and process parameters were the same as in Example 1, resulting in the product quartz.

[0067] Table 4. Chemical composition of quartz in Comparative Example 1 (mg / kg)

[0068]

[0069] Figure 2 The image shown is the XRD pattern of iron concentrate 1 in Example 1. Figure 2 It can be seen that the peak values ​​of Fe2O3 and FeO(OH) in iron concentrate 1 are also significantly increased, indicating that magnetic separation significantly improves the grade of iron concentrate.

[0070] This invention is not limited to the above-described embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this invention.

Claims

1. A method for preparing 4N quartz from high-silicon iron ore waste, characterized in that, Includes the following steps: (1) Desliming-magnetic separation: First, the high-silicon iron ore waste is deslimed and then subjected to multi-stage magnetic separation. The first stage of strong magnetic separation is 1.8~2.1T. After magnetic separation, the first iron concentrate and silicon concentrate are obtained. Then, the first iron concentrate is subjected to the second stage of magnetic separation with a magnetic field strength of 1.5~1.6T to obtain the second iron concentrate. (2) Atmospheric pressure leaching: The silica concentrate obtained in step (1) is ball-milled to a predetermined fineness, and leached under atmospheric pressure using a ternary mixed acid. The leached product is washed to neutral and dried to obtain the first high-purity quartz. (3) High-temperature hot-press leaching: The first high-purity quartz is ball-milled to a set fineness, and the ball-milled first high-purity quartz is leached by high-temperature hot-press leaching using ternary mixed acid to obtain the acid-washed product; (4) Heat treatment: The acid-washed product obtained in step (3) is washed until neutral, dried and then heat-treated to obtain the second high-purity quartz, which is the 4N quartz product. The ternary mixed acid is a mixture of sulfuric acid, phosphoric acid, and hydrofluoric acid in a volume ratio of 1~3:1~3:1; The composition of the high-silicon iron ore waste is as follows: free SiO2 content is 65-78%, iron grade is 8-15%, and -200 mesh content accounts for 10-24%.

2. The method for preparing 4N quartz from high-silicon iron ore waste according to claim 1, characterized in that, In step (1), a wet high-intensity magnetic separator or a high-gradient magnetic separator is used for magnetic separation.

3. The method for preparing 4N quartz from high-silicon iron ore waste according to claim 1, characterized in that, In step (1), the slurry ratio of the first stage of strong magnetic separation is 1:5~10.

4. The method for preparing 4N quartz from high-silicon iron ore waste according to claim 1, characterized in that, In step (1), the slurry ratio of the second stage magnetic separation is 1:5~10.

5. The method for preparing 4N quartz from high-silicon iron ore waste according to claim 1, characterized in that, In step (2), the atmospheric pressure leaching process is as follows: the acid concentration is 9~10 mol / L, the atmospheric pressure leaching time is 5~6 h, the reaction temperature is 90~100℃, and the liquid-solid ratio is 4~5 mL:1 g.

6. The method for preparing 4N quartz from high-silicon iron ore waste according to claim 1, characterized in that, In steps (2) and (3), zirconium balls are used as grinding media during the ball milling process, and nylon screens are selected as the sieves.

7. The method for preparing 4N quartz from high-silicon iron ore waste according to claim 1, characterized in that, In step (3), the high-temperature hot-press leaching process is as follows: the acid concentration is 9~10mol / L, the leaching time is 5~8h, the reaction temperature is 180~200℃, and the liquid-solid ratio is 4~5mL:1g.

8. The method for preparing 4N quartz from high-silicon iron ore waste according to claim 1, characterized in that, In step (4), the heat treatment process is specifically: high temperature treatment at 900~1000℃ in a tubular furnace for 3~5 hours.

9. The method for preparing 4N quartz from high-silicon iron ore waste according to claim 1, characterized in that, The second stage of magnetic separation involves one or more magnetic separations of the first iron concentrate.

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