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Article

The Migration Phenomenon of Metal Cations in Vein Quartz at Elevated Temperatures

by
Zhenxuan Wang
1,2,
Hongjuan Sun
1,2,*,
Bo Liu
1,2,
Yehao Huang
3 and
Tongjiang Peng
1,2
1
Key Laboratory of Solid Waste Treatment and Resource Recycle of Ministry of Education, Southwest University of Science and Technology, Mianyang 621010, China
2
Institute of Mineral Materials and Applications, Southwest University of Science and Technology, Mianyang 621010, China
3
Henan Institute of Ultrapure Mineral Materials, Zhengzhou 450016, China
*
Author to whom correspondence should be addressed.
Minerals 2025, 15(12), 1318; https://doi.org/10.3390/min15121318
Submission received: 10 November 2025 / Revised: 2 December 2025 / Accepted: 15 December 2025 / Published: 17 December 2025
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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Versions Notes

Abstract

With the rapid development of the photovoltaic (PV) and semiconductor fields, the reserves of traditional high-purity quartz raw materials can no longer meet the demands of various industries, creating an urgent need to develop new types of high-purity quartz feedstock. In this study, three groups of vein quartz samples from different mining areas were subjected to calcination at 950 °C for 2 h. The impurity states of the vein quartz before and after calcination were characterized using XRD, ICP, Raman and XRF. The migration behavior of metal cations in vein quartz under high-temperature conditions was systematically investigated, and the structural changes in the vein quartz before and after calcination were discussed from the perspectives of impurity element distribution and phase transformation. The results demonstrate that impurity cations in vein quartz migrate from the interior to the surface of the material under high-temperature environments. Quantitative ICP analysis of the inner and outer layers of the quartz samples before and after calcination revealed that, among the three groups, the surface impurity cation content of the sample with the most pronounced migration effect reached four times that of its internal structure. Combined with other characterization techniques, it was confirmed that after the cation migration process, the vein quartz samples exhibited a layered structure from the surface to the interior: a hematite mineralized layer, a high lattice impurity layer, and a low lattice impurity layer. This indicates that high-purity vein quartz with low lattice impurity content can be obtained by subjecting quartz to high-temperature calcination and subsequently removing the mineralized layer and the surface high lattice impurity layer. Consequently, vein quartz of ordinary quality can also be converted into high-purity quartz raw material of 4N grade or higher through the processes of cation migration and tailing removal.

1. Introduction

High-purity quartz is a kind of mineral obtained by purification of raw materials such as crystals, vein quartz, granite, and pegmatite. Being the material basis of high-end products in silicon-based industry, it is widely used in strategic emerging fields. With the rapid development of the global technology and material production, the demand for high-purity quartz in semiconductor manufacturing, optical communication, aerospace engineering and other sectors continues to grow [1,2,3]. It has been suggested that high-purity quartz be included in the China’s strategic non-metallic mineral list. It is noteworthy that even though the output of high-purity quartz in China has increased year after year, the import of this material has remained at a high level, reaching nearly 160,000 tons in 2017 as the highest point in history. High-purity quartz sand is originally processed from primary and secondary natural crystals. Meanwhile, because of the increasing market demand in the past two decades, natural crystal resources have gradually dried up, and alternative raw materials must be found. At present, the core technology of purifying and producing high-purity quartz sand from natural rock minerals in China is still not fully explored [4,5]. Therefore, it is of great significance to find suitable quartz raw materials and carry out targeted purification research.
As far as the distribution of quartz raw materials in nature is concerned, the ore types of quartz raw materials are very diverse. According to the deposit sources, there are natural quartz crystals, quartz sandstone, quartzite, vein quartz, powder quartz, quartz sand and granite quartz. In addition to natural quartz ore, some attempts have been made to use tailings rich in quartz resources as high-purity quartz raw materials for purification experiments [6]. Although there are various types of quartz ores and abundant reserves in nature, high-quality ores that can serve as high-purity quartz raw materials are extremely scarce. Among them, hydrothermal vein quartz is one of the ideal raw materials for the preparation of high-purity quartz because of its abundant reserves and SiO2 content higher than 99%. Various studies have shown that the main difficulty in the production of high-purity or ultra-high-purity quartz using vein quartz is the elimination of inclusions and impurity ions from the quartz lattice [7]. In spite of the fact that impurity ions in quartz inclusions and lattices can be effectively removed by HF acid leaching and chlorination roasting of vein quartz, HF and Cl2 cause serious environmental pollution when used in large-scale industrial production [7,8,9]. Therefore, finding or optimizing methods to remove inclusions and Lattice-bound impurities in quartz is of great significance for the deep purification of the material [10].
Heat treatment is a common technique in quartz processing and purification industries due to its advantages of simple operation, easy realization, and prevention of impurity mixing [11,12]. For example, high-temperature calcination can induce the crystal transformation of a low-temperature α quartz phase, leading to the decrease in hardness and the increase in brittleness, which is beneficial to crushing and deep processing of quartz [8,13]. In addition, calcination pretreatment also causes the internal inclusions of quartz to break under thermal stress to form microcracks, which is conducive to the exposure of impurities in inclusions and cracks, as well as their removal in subsequent processes, allowing for deep purification of quartz [2,14]. However, existing studies still have significant limitations: first, they lack systematic elaboration on the migration behavior, occurrence state of metal cations in quartz within the commonly used temperature range (900–1000 °C) for heat treatment and their correlation with impurity removal efficiency, especially the lack of quantitative characterization data to support the quantitative analysis of migration mechanisms; second, most of the existing green purification technologies remain in the laboratory exploration stage, and the heat treatment-subsequent separation combined process for vein quartz lacks industrial-scale optimization verification, making it difficult to directly guide large-scale production; third, the research on the coupling relationship between the occurrence form of impurities and migration laws in alternative raw materials (vein quartz) is not in-depth enough, resulting in the lack of accurate theoretical basis for the design of purification processes.
Therefore, in order to directly explore the influence of heat treatment on the purification of quartz, vein quartz ores from three different mining areas were selected in this work as raw materials to be exposed to calcination at 950 °C as a fixed experimental condition. 950 °C falls within the commonly used temperature range of 900–1000 °C for quartz heat treatment. It can not only provide sufficient thermal kinetic energy for cation migration, ensuring a surface impurity enrichment rate, but also avoid excessive thermal damage and energy consumption waste, achieving a balance between “efficiency and cost”. The morphology, structure, encapsulation degree and metal element content before and after calcination were characterized and analyzed to elucidate the effect of calcination on the migration of impurities in vein quartz.

2. Experimental Materials and Methods

2.1. Raw Materials and Equipment for Testing

The vein quartz samples utilized in this experiment were collected from Shiyan (Hubei Province) and Kangding (Sichuan Province). These samples are mainly hosted in the interior of granite bodies, the contact zones of these bodies, or metamorphic rocks adjacent to such zones, and all belong to magmatic-hydrothermal-type vein quartz. The samples were labeled as MH, GYG and KDK according to relevant mining areas. Among them, MH and GYG were taken from the interior of the mountain in the Guanyingou mining area of Shiyan City, Hubei Province. KDK was collected from the mining area of Guza County (Kangding, Sichuan Province) via mechanical crushing sampling inside the mine.
The raw MH-W, GYG-W and KDK-W ores were ground to below 400 mesh size, and the X-ray fluorescence spectrum diffraction analysis was carried out. The chemical composition results are shown in Table 1.
According to the XRF data, the purity of SiO2 in the three quartz veins was higher than 99%, and the impurities were mainly composed of CaO, P2O5, SO3, Al2O3 and Fe2O3. It shows that vein quartz has good purification potential in terms of chemical composition.
Equipment: XT-8812 hot air circulation drying oven (Shanghai Shengxin Experimental Equipment Co., Ltd., Shanghai, China), KQ5200DE CNC ultrasonic cleaner (Wuhan Jiyi Instrument & Equipment Co., Ltd., Wuhan, China), XJ-20 digest instrument (Nanjing Binzhenghong Co., Ltd., Nanjing, China), SX-10-12DII box high temperature furnace(Tianjin Taisite Experimental Equipment Co., Ltd., Tianjin, China), diamond groove grinding tool (Lijian Tools, China), and agate mortar (Lichen Instrument & Equipment Co., Ltd., China) were used in this research.

2.2. Experimental Method

(1) Raw material pretreatment
In order to avoid the introduction of extraneous impurities, quartz samples from three mining areas were coated with organic fiber cloth and crushed with a jaw crusher to achieve the average particle size of 30 mm. The crushed bulk quartz samples were then repeatedly washed with deionized water and ultrasonically cleaned in an oxalic acid solution with a mass fraction of 5% to remove clay minerals and amorphous impurities attached to the surface of quartz. The ultrasonic power employed for ultrasonic cleaning was 200 W, and the cleaning process was conducted at 60 °C for 30 min. The quartz samples after cleaning, referred to as MH-W, GYG-W and KDK-W, respectively, were dried in a hot air circulation drying oven at 105 °C.
(2) Calcination
The dried MH-W, GYG-W and KDK-W samples were put into different covered cristobalite crucibles, which were afterward exposed to heating in a high-temperature furnace at a heating rate of 10 °C/min to a temperature of 950 °C. After holding at 950 °C for 2 h, the furnace was cooled down to room temperature, and the calcined quartz samples (referred to as MH-C, GYG-C, and KDK-C, respectively) were obtained. The surface and internal parts of the samples were labeled as MH-C-S, GYG-C-S, KDK-C-S and MH-C-I, GYG-C-I, KDK-C-I, respectively. The calcination was conducted under an air atmosphere, with the muffle furnace equipped with air exchange holes to facilitate air circulation with the external environment. Six replicate samples were collected from each group, and both the sampling and grinding processes were performed in a clean bench.
(3) Sampling
The washed (MH-W, GYG-W, and KDK-W) and calcined (MH-C, GYG-C, and KDK-C) quartz materials (each taken in an amount of 50 g) were selected for further sampling. In particular, the surface and fracture surface were grooved and sampled using a diamond graver. The surface of each specimen was sampled every 5 mm along the longest direction of the transverse axis, and the sampling groove size was 2 × 8 mm. The samples obtained through the above operation were mixed and ground to below 200 mesh.
The overall sample preparation and sampling process is shown in Figure 1.

2.3. Characterization Methods

The main chemical elements composing the samples were detected using an Axios X-ray fluorescence spectrometer (XRF) (Malvern Panalytical B.V., Almelo, The Netherlands). The trace element components were determined by employing iCAP7400 (Thermo Fisher Scientific, Waltham, MA, USA) full-wavelength coverage instrument and Nexion300 X (PerkinElmer, Shelton, CT, USA) mass spectrometer. To ensure data accuracy and eliminate interference, the samples for ICP testing were prepared as mixed samples of six replicate samplings. Three parallel tests were conducted, and the average value was adopted for subsequent analysis. The phase structures were analyzed using an Ultra X-ray diffractometer (Rigaku Corporation, Tokyo, Japan) equipped with a Cu target tube at a voltage of 40 kV and a current of 40 mA within a scan range of 3–80° at a scanning speed of 20°/min. The micro-morphology and micro-area composition analysis of the samples were conducted using InVia laser Raman spectrometer (Raman) (Renishaw plc, Gloucestershire, UK) produced by Rainey Company in the United Kingdom.

3. Result and Discussion

3.1. The Change in Morphology Before and After Calcination

Figure 2 shows the morphology of MH, GYG and KDK samples before and after calcination. According to Figure 2a–c, the vein quartz samples before calcination were mainly translucent crystals, exhibiting dense grains without obvious cracks. Except for a small amount of surface impurities resistant to ultrasonic scrubbing, there were no impurities that might be visible to the naked eye. In Figure 2d–f, reddish-brown films were observed on the surface of the samples after calcination, which were assumed to be the oxidized iron-containing mineral layers. These layers were more pronounced than the original surface impurity layer, indicating that internal impurities could migrate to the surface of the vein quartz under the action of thermal stress after calcination. The interior of the calcined sample changed from translucent to more uniform milky white, whereas the section had a greasy luster, and the cracks between the grains increased. By comparing and analyzing the internal and surface morphology characteristics of the calcined samples, it was concluded that iron-containing impurities in the calcined vein quartz were predominately settled within the surface of minerals.

3.2. The Change in Phase Structure Before and After Calcination

Figure 3 displays the XRD patterns of MH, GYG and KDK samples before and after calcination. Conforming to the standard PDF card, no impurity mineral phases other than quartz were detected before calcination, confirming high purity degree of the sample. After calcination at 950 °C, the phase composition of the sample did not change significantly, indicating that the vein quartz still maintained its quartz phase crystal structure. It is noteworthy that even though reddish-brown film layers were detected after calcination, no relevant phases were identified because their content might be lower than the XRD detection limit or the crystallinity of the film layers was poor.
A comparative analysis of the XRD patterns of the surface and interior of the calcined vein quartz revealed no significant differences in the mineral compositions between the three mining areas. However, some of the diffraction peaks from the calcined surface, such as (112) and (103), weakened or disappeared compared with those acquired from the internal structure, meaning that the crystallinity of the sample surface was reduced. As shown in Table 2, in addition, the cell volume on the surface after calcination was larger than that inside the sample, confirming that the lattice-bound impurities in the quartz structure are positively correlated with the cell volume [15]. Given the fitted unit cell volume data obtained on the inner surface of a series of samples after calcination, the amount of superficial Lattice-bound impurities exceeded that of internal impurities. This might be related to the possible migration of impurities from the inside of the vein quartz to the surface layer.

3.3. Changes in Raman Spectra Before and After Calcination

Figure 4 depicts the Raman spectra of MH, GYG and KDK samples before and after calcination. Figure 4a,c,e show the quartz scattering peaks of the surface layers of vein quartz samples before calcination. The sharp peaks at 466 cm−1 and 129 cm−1 indicate that the surface layers of the untreated vein quartz possess excellent crystallinity. The Raman spectra of the calcined surface area exhibited more scattering signals in addition to those of original quartz. Applying the RRUFF spectrum database, it was established that these Raman peaks were generated by the Eg optical vibration mode and the second-order 2LO phonon vibration mode of hematite, respectively [16,17]. Hematite layer is distributed in the gap of quartz grains. On the one hand, the reddish-brown film layer on the surface of the calcined quartz might be a newly formed hematite layer. On the other hand, more impurities might be enriched on the surface of the quartz after calcination.
From the microscopic images in Figure 4b,d,f, it was evident that some inclusions and fine particles still existed in the internal area of quartz (MH-W-I, GYG-W-I, and KDK-W-I) before calcination. After calcination, the inclusions in the internal area of quartz (MH-C-I, GYG-C-I, and KDK-C-I) were reduced, and the overall morphology became more uniform than before calcination, but the number of cracks between grains increased. Based on the analysis of the relevant literature, it was implied that some inclusions in quartz might be broken to provide channels for the migration of impurities in quartz [18,19]. By comparing and analyzing the Raman spectra in Figure 4b,d,f, it was concluded that the inner region of quartz almost did not change after calcination, showing the sharp characteristic scattering peaks of quartz. Therefore, the calcination treatment caused little damage to the crystal structure of quartz in the inner region.

3.4. Changes in Metal Cations Before and After Calcination

Figure 5 depicts the impurity element content distributions throughout the surface and internal areas of untreated vein quartz samples. It can be seen from the figure that the quartz collected from the three mining areas contained a large number of impurity elements, mainly alkali metals or alkaline earth metal elements, such as Al, Ca, Fe, K and Na. The contents and distributions of impurity elements in the surface and internal areas of the samples had a good consistency between each other, indicating that the impurity elements were evenly distributed throughout the scanned regions. The content of impurity elements on the surface of the original vein quartz was slightly higher than that in the internal area. This might be due to the long-term contact of the quartz surface area with other minerals or amorphous impurities present in the natural environment [20].
In order to further confirm whether the calcination treatment might have promoted the migration of impurities inside the quartz, the contents of impurity elements within the surface and internal areas of the vein quartz samples from the three mining areas were determined, as shown in Figure 6. The test method involves digesting the samples with HF and analyzing the digestion solution using ICP-OES and ICP-MS.
It can be seen from Figure 6 that the relative contents of total impurity elements in the surface/internal regions of uncalcined samples MH-W, GYG-W and KDK-W were 57%/43%, 69%/31% and 52%/48%, respectively. The relative contents of total impurity elements in the surface/inner regions of MH-C, GYG-C and KDK-C after calcination were 86%/14%, 69%/31% and 82%/18%, respectively. Obviously, the three groups of vein quartz minerals after calcination have the characteristics of Al, Cr, Cu, Fe, Na, K and other metal elements migrating from the inside to the surface area. Especially in MH and KDK samples (Figure 6b,f), the total impurity elements after calcination migrated from the inside to the surface and their contents on the inner surface were 29% and 30%, respectively. The amount of the impurity elements on the surface of the calcined vein quartz sample accounted for more than 80% of their total quantity on the inner surface, which might be conducive to the subsequent deep purification [19,21].

3.5. Impurity Migration Process

According to the above characterization results, high temperature treatment can promote the migration of metal cations from the interior to the surface of the vein quartz. Given the micro-Raman data, it can be clearly seen that the distribution of the hematite mineralization layer on the surface spread along the grain gap. The relevant reports have also pointed out that internal inclusions and microcracks are broken and expanded under the action of lattice distortion and thermal stress after the quartz is heated, which can also open the channels for the outward migration of internal impurities [19]. In particular, the metal elements with large ionic radii, represented by Fe, are difficult to remain in the quartz lattice and further combine with impurities in the surface layer to mineralize in the air atmosphere so as to form a hematite layer [19,22,23].
Based on relevant studies and experimental results, it is inferred that the outward migration of cations in quartz during high-temperature calcination can be divided into the following stages.
① Quartz undergoes two crystal transitions during the calcination at 950 °C. At 573 °C, it is converted from α-quartz to β-quartz through a rapid phase transition process without involving bond breaking and recombination. At 870 °C, β-quartz is slowly transformed into β-tridymite, whereby the fracture and recombination of silicon-oxygen bonds occur. The fracture of bonds preferentially arises along the stress concentration area, that is, the fracture of inclusions and Lattice-bound impurities in quartz [24,25]. In this process, cracks formed within the impurity concentration area inside the quartz will move to the surface layer, providing a channel for the migration of impurities [18,19].
② In the process of bond breaking and recombination at 870 °C, the Si-O bond in the β-quartz unit cell is first broken at the micro level and then reconstructed. In this process, the bond energy of the M-O bond (here, M represents the metal cation in quartz) is lower than the bond energy of the Si-O bond, The bond energy of the Si-O bond is approximately 799 kJ/mol, while the bond energies of conventional metal oxides are all lower than this value—for instance, that of the Al-O bond is about 512 kJ/mol, and that of the Fe-O bond is roughly 409 kJ/mol [26]; therefore, the M-O bond is preferentially broken, allowing the metal cations to enter the migration channel [19]; At the same time, the energy required for Si-O binding during the recombination process in a high-temperature environment is higher than that for M-O binding. In order to achieve an overall steady state, the system tends to generate more stable Si-O bonds to store more energy in the form of binding, thereby squeezing the exposed metal cations and enabling them to migrate toward the non-quartz phase region.
③ While the transformation of quartz crystal forms provides the migration channels and migration power for metal cations, the surface of quartz is more easily oxidized under a high-temperature air atmosphere than the internal metal cations. As a result, a hematite mineralized layer is formed on the surface of quartz through the capture of internally migrating metal cations, appearing macroscopically as a reddish brown film covering the cracks of quartz grains.
Under the synergistic effect of the above three factors, the metal cations will migrate from the quartz phase region to the non-quartz one, and some of them will move directly to the surface mineralization layer (see Figure 7). Other metal cations that are not completely migrated will exist in the form of Lattice-bound impurities in the outer quartz layer due to the exclusion of the internal quartz phase.

3.6. Experimental Verification

To verify the effect of calcination on the outward migration of impurities in vein quartz, comparative purification experiments were performed using KDK vein quartz samples from Kangding, Sichuan as the raw material. As shown in Figure 8, two groups (Group a and Group b) were designed for the purification experiments. Specifically, Group a adopted a combined process of crushing-calcination-grinding-scrubbing-magnetic separation-flotation-acid pickling, which refers to the conventional process for preparing high-purity quartz from vein quartz raw materials. In contrast, Group b employed a combined process of crushing-calcination-autogenous grinding-screening and tailing discarding-grinding-flotation-acid leaching. The process parameters for each stage are presented in Table 3.
ICP tests were conducted on the high-purity quartz sand obtained from the two groups of experiments, with the test results shown in Table 4. The results reveal that the final purity of silicon dioxide in the high-purity quartz sand from Group a is 99.94%, while that from Group b reaches 99.992%. Although Group a exhibits a higher yield (92.11% for Group a versus 84.28% for Group b), the higher concentrate purity of Group b unequivocally confirms that impurities can spontaneously migrate to the outer surface of quartz during the calcination process, and this migration process can be applied in the preparation of high-purity quartz. This also demonstrates the practical application value of this study—namely, realizing the quality improvement, development, and utilization of vein quartz raw materials by facilitating the impurity migration process in quartz.

4. Conclusions

In this study, three groups of vein quartz samples from different mining areas were subjected to major chemical composition analysis. Combined with the macroscopic morphology images and phase structure data of the inner and outer surfaces of the raw ore before and after calcination, the variation laws of their phase composition and unit cell parameters were systematically investigated. Additionally, micro-Raman spectroscopy was employed to comprehensively analyze the microstructural and compositional characteristics of the inner and outer surfaces of quartz before and after calcination. Integrating the trace element distribution information, the following conclusions are drawn:
(1)
Major chemical composition analysis and macroscopic morphology characterization indicate that vein quartz exhibits excellent purification potential in terms of impurity element control. All three groups of vein quartz samples achieve a purity of 2N grade, serving as suitable raw materials for high-purity quartz production. Furthermore, a reddish-brown adherent layer forms on the quartz surface after calcination, providing macroscopic evidence for subsequent phase analysis.
(2)
Based on the XRD and Raman spectroscopy results, the unit cell volume of the quartz surface layer after calcination is significantly larger than that of the internal region. Moreover, the layered substance covering the quartz surface at the macroscopic scale is confirmed as a hematite layer through phase matching, revealing the evolutionary characteristics of surface phases during the calcination process.
(3)
Trace chemical composition analysis demonstrates a distinct migration phenomenon of internal cations toward the surface during calcination, with the impurity element content on the surface of calcined vein quartz samples accounting for more than 80% of the total content. Integrating multiple characterization techniques, it is inferred that after cation migration induced by calcination, a hematite adherent layer forms on the quartz surface, and Lattice-bound impurities are enriched in the surface layer. This implies that by removing the surface layer of calcined vein quartz, the internal quartz with low lattice impurity content can be utilized as a high-quality raw material for high-purity quartz preparation.
(4)
By regulating the impurity migration process of quartz and adopting the autogenous grinding and sieving process for surface tailing removal of calcined quartz, the purification potential of vein quartz raw materials can be significantly enhanced, thereby enabling the preparation of high-purity quartz sand with a grade of 4N or higher. This process features both simplicity and economy, making it applicable to practical industrial production. It realizes the high-value utilization of conventional vein quartz and effectively alleviates the demand pressure for high-purity quartz sand in fields such as photovoltaics and communications.

Author Contributions

Z.W.: Conceptualization, Methodology, Software, Investigation, Formal Analysis, Writing—Original Draft. H.S.: Data curation, Project administration, Writing—Original Draft, Funding acquisition. B.L.: Visualization, Investigation. T.P.: Resources, Supervision, Validation. Y.H.: Resources, Supervision, Validation. All authors have read and agreed to the published version of the manuscript.

Funding

This research was financially supported by the National Key Research and Development Program of China (2024YFC3907602); and Henan Province Major Science and Technology Special Funding (241100320100).

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author(s).

Acknowledgments

We sincerely acknowledge Key Laboratory of Solid Waste Treatment and Resource Recycle of Ministry of Education, Southwest University of Science and Technology providing the experimental and testing platforms.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. Schematic Diagram of Experimental and Sampling Procedures.
Figure 1. Schematic Diagram of Experimental and Sampling Procedures.
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Figure 2. The morphology of MH, GYG and KDK samples (a–c) before and (d–f) after calcination.
Figure 2. The morphology of MH, GYG and KDK samples (a–c) before and (d–f) after calcination.
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Figure 3. (a) XRD patterns of MH, GYG and KDK samples after washing; (b) XRD patterns of the surface and internal structure of MH samples after calcination; (c) XRD patterns of the surface and internal structure of GYG samples after calcination; (d) XRD patterns of the surface and internal structure of KDK samples after calcination.
Figure 3. (a) XRD patterns of MH, GYG and KDK samples after washing; (b) XRD patterns of the surface and internal structure of MH samples after calcination; (c) XRD patterns of the surface and internal structure of GYG samples after calcination; (d) XRD patterns of the surface and internal structure of KDK samples after calcination.
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Figure 4. Raman spectra of (a,c,e) the surface areas and (b,d,f) the inner region of MH, GYG and KDK samples before and after calcination, respectively.
Figure 4. Raman spectra of (a,c,e) the surface areas and (b,d,f) the inner region of MH, GYG and KDK samples before and after calcination, respectively.
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Figure 5. The contents of impurity elements in the surface and inner regions of uncalcined vein quartz samples, (a) Element distribution in the inner and outer layers of MH sample before calcination; (b) Element distribution in the inner and outer layers of GYG sample before calcination; (c) Element distribution in the inner and outer layers of KDK sample before calcination.
Figure 5. The contents of impurity elements in the surface and inner regions of uncalcined vein quartz samples, (a) Element distribution in the inner and outer layers of MH sample before calcination; (b) Element distribution in the inner and outer layers of GYG sample before calcination; (c) Element distribution in the inner and outer layers of KDK sample before calcination.
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Figure 6. The relative content distributions of impurity elements on the surface and inner layer of quartz: (a,c,e) before and (b,d,f) after calcination, respectively.
Figure 6. The relative content distributions of impurity elements on the surface and inner layer of quartz: (a,c,e) before and (b,d,f) after calcination, respectively.
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Figure 7. Impurity migration and occurrence state diagram upon the calcination process.
Figure 7. Impurity migration and occurrence state diagram upon the calcination process.
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Figure 8. KDK Purification Process Flow Diagram ((a). morphology of calcined products in Group a experiment; (b). morphology of calcination-auto-grinding products in Group b experiment).
Figure 8. KDK Purification Process Flow Diagram ((a). morphology of calcined products in Group a experiment; (b). morphology of calcination-auto-grinding products in Group b experiment).
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Table 1. Chemical compositions of raw materials.
Table 1. Chemical compositions of raw materials.
Component (%)SiO2CaOP2O5SO3Al2O3Fe2O3BaOMgOCr2O3Cs2OIgnition Loss
MH-W99.570.100.100.02*0.16**0.040.020.39%
GYG-W99.680.030.020.120.050.020.030.05**0.58%
KDK-W99.320.090.080.020.450.02*0.02**0.62%
* Indicates not detected.
Table 2. Comparison Table of Unit Cell Volumes Between Surface and Internal Layers of Samples After Calcination.
Table 2. Comparison Table of Unit Cell Volumes Between Surface and Internal Layers of Samples After Calcination.
Sample NameUnit Cell Volume (Å3)
Surface SamplesInternal Samples
MH-C113.58112.78
GYG-C113.26113.12
KDK-C113.22113.12
Table 3. Comparison of experimental process parameters.
Table 3. Comparison of experimental process parameters.
Group aGroup b
Workshop SectionParameterWorkshop SectionParameter
crushingJaw crusher with zirconia liner to break down to 10 mm.crushingJaw crusher with zirconia liner to break down to 10 mm.
calcinationThe samples were calcined at 900 °C for 120 min in oxygen atmosphere.calcinationThe samples were calcined at 900 °C for 120 min in oxygen atmosphere.
grindingThe sample was ground to 70~150 mesh using a zirconia lining disc prototype.autogenous grindingAutogenous grinding for 5 min using zirconia-lined self-grinding mill.
scrubbingScrub with 5% mass fraction of oxalic acid solution.screeningFine tailings with particle size less than 100 mesh are sieved and discharged.
magnetic separationUsing a wet high intensity magnetic separator with a magnetic flux of 23,000 Oe, magnetic separation is performed once at a pulp concentration of 20%.grindingThe sample was ground to 70~150 mesh using a zirconia lining disc prototype.
flotationSlurry concentration 20%, pH ≈ 2.5, regulator HF, collector dodecylamine.flotationSlurry concentration 20%, pH ≈ 2.5, regulator HF, collector dodecylamine.
acid pickling0.4 mol/L HF, 1.2 mol/L HCl, solid–liquid ratio of 1:1, acid leaching at 80 °C for 4 h.acid pickling0.4 mol/L HF, 1.2 mol/L HCl, solid–liquid ratio of 1:1, acid leaching at 80 °C for 4 h.
Table 4. Chemical composition test results of comparative experiments (μg/g).
Table 4. Chemical composition test results of comparative experiments (μg/g).
ElementAlCaCrCuFeKLiNaMgMnNiPTiSUM
KDK-a351.92134.640.420.0722.108.761.448.5514.201.900.629.232.49556.33
KDK-b36.5810.970.300.165.733.230.567.044.500.320.193.242.5175.32
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Wang, Z.; Sun, H.; Liu, B.; Huang, Y.; Peng, T. The Migration Phenomenon of Metal Cations in Vein Quartz at Elevated Temperatures. Minerals 2025, 15, 1318. https://doi.org/10.3390/min15121318

AMA Style

Wang Z, Sun H, Liu B, Huang Y, Peng T. The Migration Phenomenon of Metal Cations in Vein Quartz at Elevated Temperatures. Minerals. 2025; 15(12):1318. https://doi.org/10.3390/min15121318

Chicago/Turabian Style

Wang, Zhenxuan, Hongjuan Sun, Bo Liu, Yehao Huang, and Tongjiang Peng. 2025. "The Migration Phenomenon of Metal Cations in Vein Quartz at Elevated Temperatures" Minerals 15, no. 12: 1318. https://doi.org/10.3390/min15121318

APA Style

Wang, Z., Sun, H., Liu, B., Huang, Y., & Peng, T. (2025). The Migration Phenomenon of Metal Cations in Vein Quartz at Elevated Temperatures. Minerals, 15(12), 1318. https://doi.org/10.3390/min15121318

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