Method for preparing quartz particles by removing fine-grained kaolinite from kaolin tailings

Abstract

The invention provides a method for preparing quartz particles by removing fine-grained kaolinite from kaolin tailings, and the method comprises the following steps: crushing and screening quartz raw ore in the kaolin tailings to obtain first quartz particles with the particle size of 0.106-0.212 mm; calcining the second quartz particles to enable the kaolinite to be subjected to dehydroxylation phase change into calcined kaolinite, so as to obtain second quartz particles; mechanically scrubbing the second quartz particles to realize preliminary stripping of the calcined kaolinite, so as to obtain third quartz particles; and finally, carrying out acid ultrasonic synergistic scrubbing, water washing, filtering and drying treatment on the third quartz particles to obtain the quartz particles. The purity of the quartz particles is remarkably improved through calcination transformation and mechanochemical cooperative treatment, the bottleneck problem of quartz utilization caused by kaolinite residues is effectively solved, and the method is suitable for industrial preparation of high-end quartz materials.

Description

Technical Field

[0001] This invention relates to the field of high-purity mineral material preparation and comprehensive resource utilization technology, specifically to a method for preparing quartz particles by removing fine-grained kaolinite from kaolin tailings. Background Technology

[0002] Kaolin is an important non-metallic mineral, widely used in ceramics, papermaking, coatings, rubber and other fields. my country is rich in kaolin resources. During its mining and beneficiation process, a large amount of tailings waste is generated. These tailings typically contain more than 90% quartz, making them a high-quality potential raw material for the preparation of quartz sand, with great prospects for resource utilization.

[0003] However, because kaolin and quartz often coexist and intercalate closely during natural mineralization, even after conventional crushing, grinding, and sorting processes (such as gravity separation, magnetic separation, and flotation), a large number of micron-sized or even submicron-sized fine-grained kaolinite group minerals (mainly kaolinite) remain firmly attached to the surface of quartz particles or fill the micro-fractures within the quartz. This dense state of occurrence makes it difficult for traditional physical beneficiation methods to effectively remove these impurities. The residue of kaolinite introduces a large amount of aluminum impurities, severely reducing the chemical purity of quartz and diminishing its potential for high-value utilization.

[0004] Currently, research on the purification of quartz in kaolin tailings is still in its early stages. Conventional treatment methods have significant limitations. Physical methods (such as gravity separation and magnetic separation) are mainly effective for impurity minerals with large differences in density or magnetic properties. For kaolinite, which has similar physicochemical properties to quartz and has complex intergrowth relationships, the separation effect is minimal, and it cannot solve the problems of surface adhesion and fissure filling. Although chemical acid washing can dissolve some aluminum-containing impurities, the acid solution is difficult to effectively penetrate and contact kaolinite that is wrapped by quartz particles or embedded deep in narrow fissures, resulting in low reaction efficiency, high acid consumption, long treatment cycle, and unsatisfactory economic and environmental performance. Mechanical scrubbing alone can remove some loosely attached impurities on the surface, but its ability to remove fine kaolinite particles adsorbed through strong forces such as hydrogen bonds and van der Waals forces inside fissures is limited, resulting in insufficient purification depth.

[0005] Therefore, there is an urgent need to develop an efficient, economical removal method suitable for large-scale application in order to overcome the technical bottleneck in the purification of quartz from kaolin tailings. Summary of the Invention

[0006] The purpose of this invention is to address at least one of the aforementioned deficiencies in the prior art. For example, one objective of this invention is to provide a method for preparing quartz particles by removing fine kaolinite from kaolin tailings; another objective of this invention is to provide quartz particles.

[0007] To achieve the above objectives, the present invention provides a method for preparing quartz particles by removing fine kaolinite from kaolin tailings, the method comprising the following steps: 1) The kaolin tailings were crushed and screened to obtain the first quartz particles; 2) The first quartz particles are calcined to obtain the second quartz particles; 3) The second quartz particle is mechanically scrubbed to obtain the third quartz particle; 4) Post-process the third quartz particles to obtain quartz particles.

[0008] Optionally, the SiO2 content in the kaolin tailings is 70% to 95%; the minerals in the kaolin tailings include one or more of kaolin-associated quartz, gravelly quartz, and powdered quartz.

[0009] Alternatively, the sieving in step 1) is performed by sieving the first quartz particles with a particle size of 0.106~0.212 mm using a standard analytical sieve.

[0010] Alternatively, the calcination in step 2) can be carried out in a high-temperature device at a temperature of 500-700°C for 30-120 minutes.

[0011] Optionally, the mechanical scrubbing in step 3) is carried out in a high-speed mixing device with a mixing rate of 200-500 rpm; the mechanical scrubbing time is 30-120 min.

[0012] Alternatively, the post-processing described in step 4) includes acid ultrasonic scrubbing, water washing, filtration, and drying.

[0013] Alternatively, the acid ultrasonic scrubbing involves placing the third quartz particles in an acidic medium and performing deep scrubbing under ultrasonic conditions; the water washing involves washing the acid ultrasonically scrubbed third quartz particles with ultrapure water until the filtrate is neutral.

[0014] Optionally, the acidic medium is a solution prepared by mixing one or more inorganic or organic acids with deionized water, and the concentration of the solution is 0.2~1 mol / L; the inorganic acid includes hydrochloric acid, nitric acid or sulfuric acid, and the organic acid includes oxalic acid; the ultrasonic time is 30~120 min.

[0015] In another aspect, the present invention provides quartz particles that can be prepared by the method described above for preparing quartz particles by removing fine kaolinite from kaolin tailings.

[0016] Alternatively, the SiO2 content in the quartz particles is greater than 97.00%.

[0017] Compared with the prior art, the beneficial effects of the present invention include at least one of the following: (1) The method of the present invention removes fine kaolinite from quartz sand by calcination, which can transform kaolinite into calcined kaolinite by dehydroxylation, thereby increasing its activity and dispersibility, which is beneficial to the removal of kaolinite.

[0018] (2) The method of the present invention removes fine kaolinite from quartz sand by calcination, which can open the micro-cracks in quartz and is more conducive to the removal of other gangue impurities.

[0019] (3) The method of the present invention removes fine kaolinite from quartz sand by calcination, providing a raw material with high purity that can be used to prepare high-purity quartz sand.

[0020] (4) The method of the present invention has a simple process flow, mild conditions and wide applicability, and is suitable for large-scale high-value utilization of quartz resources in kaolin tailings. Attached Figure Description

[0021] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which: Figure 1 A scanning electron microscope analysis image of the raw material in Example 1 of the present invention is shown.

[0022] Figure 2 The image shows a scanning electron microscope analysis of the raw material after direct acid ultrasonic scrubbing in Example 1 of the present invention.

[0023] Figure 3 The image shows a scanning electron microscope analysis of the raw material after calcination followed by acid ultrasonic cleaning in Example 1 of the present invention. Detailed Implementation

[0024] In the following, a method for preparing quartz particles by removing fine kaolinite from kaolin tailings according to the present invention will be described in detail with reference to exemplary embodiments.

[0025] It should be noted that "first," "second," "third," etc., are merely for the convenience of description and distinction, and should not be interpreted as indicating or implying relative importance.

[0026] This invention proposes a removal process that combines calcination transformation with mechanochemical synergistic treatment. The core of this process is to promote the structural transformation of kaolinite through calcination, and to achieve deep purification of quartz particles by combining mechanical scrubbing with acid and ultrasonic synergistic effects. This provides a raw material guarantee for the preparation of high-value-added quartz materials and realizes the high-value utilization of quartz resources.

[0027] Exemplary Example 1 This exemplary embodiment provides a method for preparing quartz particles by removing fine kaolinite from kaolin tailings, the method comprising the following steps: S1. The kaolin tailings are crushed and screened to obtain the first quartz particles.

[0028] In this embodiment, the SiO2 content in the kaolin tailings is 70%~95%; the minerals in the kaolin tailings include one or more of kaolin-associated quartz, gravelly quartz, and powdered quartz.

[0029] In this embodiment, the sieving is performed by using a standard analytical sieve to separate the first quartz particles with a particle size of 0.106~0.212mm.

[0030] In this embodiment, the crushing can be carried out using a closed coal sampler, a vibratory mill, an impact crusher, or a roller crusher, wherein the crushing ratio is 2 to 15, for example, 3, 5, 9, and 14.

[0031] S2. The first quartz particle is calcined to obtain the second quartz particle.

[0032] In this embodiment, the calcination is carried out in a high-temperature device, which includes a box-type muffle furnace, a tube furnace, and a vacuum atmosphere furnace, etc.; the calcination temperature is 500~700℃, for example 501℃, 550℃, 600℃, and 695℃, etc.; the calcination time is 30~120min, for example 32min, 50min, 85min, and 119min, etc.

[0033] In this embodiment, the calcination process promotes the dehydroxylation and phase transformation of kaolinite, transforming it into calcined kaolinite. This process destroys the crystal structure and enhances its activity. More importantly, it is accompanied by volume shrinkage and crack expansion, which is beneficial for the subsequent removal of impurities.

[0034] S3. Mechanically scrub the second quartz particle to obtain the third quartz particle.

[0035] In this embodiment, the mechanical scrubbing is carried out in a high-speed stirring device, with a stirring rate of 200~500 rpm, such as 210 rpm, 280 rpm, 350 rpm and 490 rpm; the mechanical scrubbing time is 30~120 min, such as 31 min, 55 min, 90 min and 119 min.

[0036] In this embodiment, the mechanical scrubbing needs to be carried out until the supernatant of the system is clear.

[0037] In this embodiment, the mechanical scrubbing can use mechanical shearing force to peel the calcined kaolinite off the quartz surface as a whole, and to initially remove the impurity minerals adhering to the surface of the quartz particles.

[0038] S4. Post-process the third quartz particles to obtain quartz particles.

[0039] In this embodiment, the post-processing includes acid ultrasonic scrubbing, water washing, filtration, and drying.

[0040] In this embodiment, the acid ultrasonic scrubbing involves placing the third quartz particles in an acidic medium and performing deep scrubbing under ultrasonic conditions; the water washing involves washing the acid ultrasonically scrubbed third quartz particles with ultrapure water until the filtrate is neutral; and the drying involves drying at 105°C for 4 to 6 hours, for example, 4.2 hours, 4.9 hours, 5.5 hours, and 5.9 hours.

[0041] In this embodiment, the acidic medium is a solution prepared by mixing one or more inorganic or organic acids with deionized water, and the concentration of the solution is 0.2~1 mol / L, such as 0.21 mol / L, 0.3 mol / L, 0.55 mol / L and 0.99 mol / L.

[0042] In this embodiment, the inorganic acid includes hydrochloric acid, nitric acid or sulfuric acid, and the organic acid includes oxalic acid; the ultrasound time is 30~120min, for example 31min, 62min, 85min and 118min.

[0043] Exemplary Example 2 This exemplary embodiment provides quartz particles that can be prepared by the method described in Exemplary Embodiment 1 for preparing quartz particles by removing fine kaolinite from kaolin tailings.

[0044] In this embodiment, there is almost no kaolinite residue on the surface and in the cracks of the quartz particles, and the purity of SiO2 is significantly improved. This makes it suitable for high-purity quartz sand applications, such as high-purity quartz sand, quartz glass, optical fibers, and photovoltaic silicon materials, which are high-value-added application fields.

[0045] In this embodiment, the SiO2 content in the quartz particles is greater than 97.00%.

[0046] To better understand the exemplary embodiments of the present invention described above, further explanation is provided below with reference to specific examples.

[0047] Example 1 This example demonstrates the preparation of quartz particles using the preparation method described in this invention.

[0048] This example uses kaolin tailings from a certain area in Maoming as raw material, with a quartz content of approximately 86%, a kaolinite content of approximately 9.9%, and other impurities accounting for approximately 4%. The operation steps include: crushing and screening the raw quartz ore in the kaolin tailings to obtain first quartz particles with a particle size of 0.106-0.212 mm; calcining the first quartz particles to obtain second quartz particles; mechanically scrubbing the second quartz particles to obtain third quartz particles; and subjecting the third quartz particles to acid ultrasonic scrubbing, water washing, filtration, and drying to obtain quartz particles. The details are as follows: (1) A vibratory grinding mill with a zirconium oxide liner was used to crush the kaolin tailings. The crushing ratio was 1.8. The quartz particles were screened using a standard analytical sieve to obtain the first quartz particles with a particle size of 0.106-0.212 mm.

[0049] (2) The first quartz particles were calcined at 600°C for 1 hour using a box-type muffle furnace to obtain the second quartz particles.

[0050] (3) The second quartz particles were mechanically scrubbed using a mixer to peel off the calcined kaolinite from the quartz surface in one piece, and to remove the impurities adhering to the surface of the quartz particles until the supernatant was no longer turbid, thus obtaining the third quartz particles. The stirring speed was 400 rpm and the time was 3 min.

[0051] (4) The third quartz particles were subjected to acid ultrasonic scrubbing, water washing, filtration and drying to obtain quartz particles.

[0052] The third quartz particle was placed in a 1 mol / L HCl solution and subjected to acid ultrasonic scrubbing for 30 min to remove calcined kaolinite from smaller crevices; it was then repeatedly rinsed with ultrapure water until the pH value of the quartz surface was 7; it was filtered using a Buchner funnel; and dried at 105℃ for 4 h.

[0053] The samples prepared in this example were tested, and the results are shown in Table 1. Table 1 shows that the oxides of aluminum, titanium, potassium, and iron were significantly reduced in both the calcined and uncalcined scrubbed samples, while the oxides of silicon were significantly increased. This indicates that scrubbing is effective in removing impurities, primarily kaolinite, and that scrubbing after calcination is significantly more effective than scrubbing before calcination in removing kaolinite.

[0054] Figure 1 This is a scanning electron microscope (SEM) image of the raw material in this example. Figure 2 This is a scanning electron microscope image showing the raw material after being directly subjected to acid ultrasonic scrubbing in this example. Figure 3 This is a scanning electron microscope (SEM) image showing the raw materials in this example after calcination followed by acid ultrasonic cleaning. Figure 1 It can be seen that a large amount of flaky kaolinite adheres to the surface of the quartz particles in the raw material. From Figure 2 , Figure 3 The comparison shows that the surface of the quartz particles that were directly scrubbed without calcination was rougher and there was a large amount of flaky kaolinite adhering and accumulating in the gaps between the quartz particles; while the surface of the quartz particles that were calcined and then scrubbed was cleaner and the kaolinite in the gaps was removed more effectively.

[0055] Table 1 Comparison of XRF results of calcination-assisted acid ultrasonic scrubbing

[0056] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the scope of the claims.

Claims

1. A method for preparing quartz particles by removing fine kaolinite from kaolin tailings, characterized in that, The method includes the following steps: 1) The kaolin tailings were crushed and screened to obtain the first quartz particles; 2) The first quartz particles are calcined to obtain the second quartz particles; 3) The second quartz particle is mechanically scrubbed to obtain the third quartz particle; 4) Post-process the third quartz particles to obtain quartz particles.

2. The method for preparing quartz particles by removing fine kaolinite from kaolin tailings according to claim 1, characterized in that, The SiO2 content in the kaolin tailings is 70%~95%; the minerals in the kaolin tailings include one or more of kaolin-associated quartz, gravelly quartz and powdered quartz.

3. The method for preparing quartz particles by removing fine kaolinite from kaolin tailings according to claim 1, characterized in that, The sieving described in step 1) involves sieving the first quartz particles with a particle size of 0.106~0.212mm using a standard analytical sieve.

4. The method for preparing quartz particles by removing fine kaolinite from kaolin tailings according to claim 1, characterized in that, The calcination described in step 2) is carried out in a high-temperature device at a temperature of 500~700℃ for a time of 30~120min.

5. The method for preparing quartz particles by removing fine kaolinite from kaolin tailings according to claim 1, characterized in that, The mechanical scrubbing described in step 3) is carried out in a high-speed mixing device at a mixing rate of 200-500 rpm; the mechanical scrubbing time is 30-120 min.

6. The method for preparing quartz particles by removing fine kaolinite from kaolin tailings according to claim 1, characterized in that, The post-processing described in step 4) includes acid ultrasonic scrubbing, water washing, filtration, and drying.

7. The method for preparing quartz particles by removing fine kaolinite from kaolin tailings according to claim 6, characterized in that, The acid ultrasonic scrubbing involves placing the third quartz particles in an acidic medium and performing deep scrubbing under ultrasonic conditions; the water washing involves washing the acid ultrasonically scrubbed third quartz particles with ultrapure water until the filtrate is neutral.

8. The method for preparing quartz particles by removing fine kaolinite from kaolin tailings according to claim 7, characterized in that, The acidic medium is a solution prepared by mixing one or more inorganic or organic acids with deionized water, and the concentration of the solution is 0.2~1 mol / L; the inorganic acid includes hydrochloric acid, nitric acid or sulfuric acid, and the organic acid includes oxalic acid; the ultrasonic time is 30~120 min.

9. A type of quartz particle, characterized in that, The quartz particles are prepared by any one of the methods described in claims 1-8 for preparing quartz particles by removing fine kaolin from kaolin tailings.

10. A quartz particle according to claim 9, characterized in that, The quartz particles contain more than 97.00% SiO2.

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