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BY-NC-ND 3.0 license Open Access Published by De Gruyter Open Access December 3, 2016

Mineralogical and chemical characteristics of a powder and purified quartz from Yunnan Province

  • Ran-Fang Zuo , Gao-Xiang Du EMAIL logo , Wei-Gang Yang , Li-Bing Liao and Zhaohui Li
From the journal Open Geosciences


For comprehensive utilization of powder quartz, a detailed mineralogical analysis is needed. In this paper, the minerals collected from a powder quartz deposit in Yunnan Province and its purification products were characterized by X-ray diffraction (XRD), chemical composition, and scanning electron microscopy (SEM) analyses. The raw powder quartz deposit had a simple mineral composition made of 85% quartz and 15% clay minerals kaolinite and illite with a trace amount of feldspar. It had narrow particle size distribution with whiteness of 81.4. The impurity minerals kaolinite and illite existed in the forms of aggregates with quartz or inclusions in quartz particles and could be easily removed. The mineralogical characterization suggested that the powder quartz deposit was formed by long-term weathering of feldspathic or felsic rocks, possible of pegmatitic origin.

1 Introduction

Handling of fine, usually submicrometer-sized, powders in large quantities requires a high degree of process control to achieve the desired microstructural characteristics, e.g., small defect size, good dispersion in other phases, and homogeneous grain-boundary composition [1]. Powder quartz, a novel siliceous material of unique application, was formed mostly by weathering of microcrystalline quartzite [2]. In China, the first powder quartz deposit was discovered in Jiangxi Province in the 1980’s, which accounts for 99% of the total reserves in China, but with low quality [3]. It was characterized with small particle sizes, easy processing, and wide application compared with traditional siliceous materials such as quartzite, quartz sand, and vein quartz, respectively [4].

The particle size of the quartz added a significant influence on its potential development [5]. Thus, fine powder quartz had its distinct advantages in its utilization. Particularly, high purity quartz has become one of today’s key strategic minerals with applications in high-tech industries that include semiconductors, high temperature lamp tubing, telecommunications and optics, microelectronics, and solar silicon applications [6]. In the lamp tubing and optics industries aluminium should not exceed 20 ppm, while other metals should be less than 1 ppm, and total impurities less than 30 ppm [6]. For semiconductor base materials and crucibles aluminium content should be even lower, specified to less than 10 ppm, other metals less than 0.1 ppm, and total impurities not to exceed 15 ppm [6].

High-purity and ultra-fine micro powder quartz could be obtained by scrubbing, magnetic separation, flotation, acid-cleaning of conventional quartz deposits [7891011]. Comprehensive studies of the purification technology of quartz deposits were also undertaken extensively [12], so as to expand its application and improve its industrial value. As quartz sands have variable degrees of purity due to variable mineral composition, only a small fraction is suitable for glassmaking and other high-grade industrial applications including foundries [13].

The production of high purity materials requires precise control of impurity contents [14]. The forms of impurities existed in powder quartz would affect its purification technology and purification products directly. Thus, mineralogical analyses of powder quartz were conducted to help promoting its comprehensive utilization. In this paper, the powder quartz from Yunnan Province was evaluated on its compositional properties and analyzed for its possible genesis. The results would be used to provide a basis for improving its mechanical properties, comprehensive development, and utilization.

2 Experimental

2.1 Materials

The powder quartz samples were collected from a powder quartz deposit in Yunnan Province, China. The deposit occurred in the lower to mid Devonian with an average thickness of 10 m. The deposit is about 3.0 M ton with an average SiO2 content of 92.47% [15]. It occurs on a shallow depth and can be mined in open pit mining.

They consisted of silica powder and silica sand with loose texture. The raw materials were analyzed first and then subject to further treatment such as dry ultrafine grinding with liquid additives [16]. The grinding consisted of two stages: (1) grinding the samples to <200 meshes; and (2) further grinding the samples to <800 meshes. In brief, the ultrafine grinding was performed in a vibration rod mill. A desired amount of quartz sample (50 g) and ethanol (5 mL) were added to the pot filled with the grinding media. After grinding the samples to desired particle size, the samples were collected for SEM observation and EDS analyses. The grinding will result in two distinct consequences: particle breakdown and mechanical activation [17]. Our goal was to utilize the fine grinding process while minimizing mechanical activation during the purification stage.

2.2 Methods of characterization

The chemical composition was analyzed using ICP-AES [18], while the mineral identification was conducted using XRD. The relationships between the host and the accessory minerals were determined by grinding the powder quartz first and then purifying the samples to different degrees as indicated by the SiO2 content. The purified minerals were further analyzed for their particle morphology. Residual impurity minerals were further identified. The genesis of the powder quartz deposit was deduced from the analytic results following the principles of minerals weathering.

The ICP analyses were performed on an ICP-AES (Thermo Jerell Ash, USA). Accuracy was checked in each analytical batch by measuring certified reference material and was found to be within ±5% of the certified values. Precision was also evaluated by measuring standard deviation of three individual runs, which was typically better than 2%.

The micromorphology of raw powder quartz and powder quartz samples purified to 98.6% and 99.6% SiO2 contents was further analyzed using SEM supplemented with energy dispersion spectrum (EDS) analysis. The SEM images were taken using a QUANATA 6000 scanning electron microscope from American FEI Company at an accelerating voltage of 25 kV.

XRD patterns were recorded by a Rigaku D/MAX-rA diffractometer (Rigaku, Japan) with a Ni-filtered CuKα radiation at 40 kV and 100 mA and a scanning speed of 2° 2θ/min at 0.02° per step. The whiteness was measured by SBDY-1 digital whiteness meter (Shanghai, China).

3 Results and Discussion

3.1 Chemical composition analysis

The species and content of impurity minerals existing in powder quartz were the main factors to affect purification of the powder quartz. The chemical composition analysis and microelement analysis of powder quartz were performed to obtain the accurate content of each component.

The major chemical analyses revealed that the powder quartz was mainly made of SiO2, yielding 93.7% (Table 1). The main impurity was Al2O3, accounting for 3.62%, followed by K2O, MgO, and Fe2O3, accounting for 0.64%, 0.26%, and 0.18% respectively. Microscopic observation showed that the impurities existing in powder quartz were in the form of K-feldspar and magnesium silicates. The contents of CaO, Na2O, MnO2, and SO3, were very low. The trace element analyses showed that Co, Cu, Pb, and Zn were at the ppb level. However, the concentrations of B and Ti (Table 2) were much higher than typical for quartz deposits of different origins [19]. The major, minor, and trace element contents, respectively, suggested that the powder quartz mine was associated with geological environment and mineralization of felsic rocks of pegmatitic origin as indicated by the higher B and Ti contents [20].

The whiteness of powder quartz was 81.4, a value suggesting that it could be used as raw material for ceramics directly. It could also be used as raw refractory materials after removal of Al. Resource exploration in this area revealed a great prospect for a large mineral deposit.

Table 1

The chemical composition analysis of powder quartz (%).

Table 2

The trace element analysis of powder quartz (mg/kg).


3.2 XRD pattern analysis

The semi-quantitative analysis showed that the contents of quartz and clay minerals were 85% and 15%, respectively. The clay minerals mainly consist of illite and kaolinite (Fig. 1).

Figure 1 The XRD pattern of powder quartz from Yunnan province.
Figure 1

The XRD pattern of powder quartz from Yunnan province.

3.3 The particle morphology and energy spectrum analysis

After the powder quartz was ground to less than 200 meshes and then purified, the SiO2 content of the sample increased to 98.6%. Further purification after grinding to 800 meshes resulted in a SiO2 content of 99.6%. The impurity minerals were significantly removed by the grading and subsequent purification processes.

3.3.1 The micromorphology analysis of raw powder quartz

Several spots were analyzed using EDS attached to the SEM (Fig. 2). Each spot was about 2 μm in diameter and the given content of impurity elements thus determined was semi-quantitative. The powder quartz samples had a characteristic high degree of weathering and flake-like impurities distributed in between quartz particles (points A and C in Fig. 2a) or on the surface of quartz particles (point B in Fig. 2a). A part of it was wrapped in weathered quartz particles or mingled in quartz particle gaps. Point I in Fig. 2b was a clay mineral particle surrounded by agglomerated particles. The EDS analyses of each point suggested that the impurity minerals were mainly kaolinite or illite as indicated by the substantial amount of K (Table 3).

Figure 2 SEM observation of raw powder quartz.
Figure 2

SEM observation of raw powder quartz.

Table 3

The energy spectrum analysis of raw powder quartz samples.

PositionMorphologyFormContent (%)Impurity minerals
Ascale aggregatefree45.506.2547.041.21kaolinite or illite
Bsheetstick to quartz surface50.551.2947.380.78kaolinite or illite
Cscale aggregatefree55.596.5936.311.50kaolinite or illite
Dunclearparticle gap42.464.9851.231.33kaolinite or illite
Eunclearparticle gap42.682.5554.050.72kaolinite or illite
Isheetwrapped in particles51.5012.8735.190.44kaolinite or illite

3.3.2 The micromorphology of purified powder quartz samples

As the particle sizes of the impurity minerals were overall less than 2 μm, grinding the materials to less than 200 or 800 meshes was needed in order to remove most of the impurity minerals. The SEM analyses of powder quartz purified after grinding to 200 and 800 meshes were shown in Figs. 3 and 4. The results of EDS analyses of impurity particle were listed in Table 4.

Table 4

The energy spectrum analysis of powder quartz after first purification.

PositionMorphologyFormContent (%)Impurity minerals
Asingle graininclusion42.073.5551.571.89kaolinite or illite
Cscale aggregatestick to quartz surface48.3214.8636.730.09kaolinite or illite
Escale aggregateparticle gap49.268.5341.081.13kaolinite or illite
Fplaty aggregateparticle gap35.496.1953.744.58potash feldspar
Gplatyparticle gap30.806.0758.494.64potash feldspar

Most of the impurity minerals were removed upon purification after ground to 200 meshes. The surface of quartz particle was clean and had regular edges (Fig. 3). However, there are still some sheet-like impurity minerals sticking to the surface of quartz particles (point C in Fig. 3a). Some platy impurity minerals were mingled in the gaps of weathered quartz particles (point E in Fig. 3b). Again, the EDS analyses suggested that they were mainly kaolinite, illite, and K-feldspar. Further purification and separation of quartz from the impurity minerals could be achieved via the size differences between quartz and impurity particles (in the range of 2 to 4 μm).

Figure 3 SEM analyses of powder quartz after first purification.
Figure 3

SEM analyses of powder quartz after first purification.

Upon further purification (i.e. after ground to 800 mesh), the particle size of quartz became uniform, about 10 μm (Fig. 4a). The impurity minerals on the surface of quartz particles disappeared. The remaining impurity particles may be attributed mainly to inclusions in the quartz particles (point A in Fig. 4b). The EDS analysis at point A showed chemical composition similar to that of kaolinite or illite, owing to the sheet-like morphology and substantial amount of Al. After the second step of purification, the remaining impurity particles (about 2 μm) existed only in the gap of quartz particles in the forms of inclusion, making further purification very difficult.

Figure 4 SEM analyses of powder quartz after second purification.
Figure 4

SEM analyses of powder quartz after second purification.

Unlike kaolinite and illite, K-feldspar was present in the gaps of quartz particles or covered by layers of platy minerals with extremely low quality, making it difficult to be observed in comparison to platy minerals.

3.4 Genetic analysis

Under acidic conditions of the diagenetic process, K-feldspar would undergo incongruent dissolution and weathering to form kaolinite, illite, and quartz. Under specific conditions, kaolinite can react with K-feldspar to form illite and quartz. The reactions could be expressed as follows:

2KAlSi3O8 (K-feldspar) + 2H++ H2O → Al2Si2O5(OH)4 (kaolinite) + 4SiO2 (quartz) + 2K+

3KAlSi3O8 (K-feldspar) + 2H++ H2O → KAl3Si3O10(OH)2 (illite) + 6SiO2 (quartz) + 2K++ H2O

Al2Si2O5(OH)4 (kaolinite) + 2KAlSi3O8 (K-feldspar) → KAl3Si3O10(OH)2 (illite) + SiO2 (quartz) + H20

The relationships between quartz and feldspar indicated that quartz was the dominant residual mineral or newly formed one, while K-feldspar was consumed in the process of incongruent dissolution. The absence or near absence of K-feldspar suggested that weathering process proceeded over a long period of time and was almost completed. The minor K-feldspar was only detected as inclusions or surrounded by clay minerals, which protect its further decomposition. The high B and Ti content suggested its pegmatitic origin.

4 Conclusion

1) The whiteness of powder quartz from Yunnan Province was 81.4 and the content of SiO2 was 93.7%. The material was mainly composed of quartz under a higher degree of weathering, coexisted with some kaolinite, illite, and trace amount of feldspar. Its simple mineral composition and small particle size distribution made it a valuable mineral resource.

2) The impurity minerals stick to the surface of quartz particles and were wrapped in quartz particles or mingled in the gap of quartz particles. The size of impurity particles was less than 2 μm. These impurity minerals could be easily removed from the quartz after grinding and purification.

3) The powder quartz was formed from feldspar or feldspar and quartz over long-term weathering, while the minor remaining K-feldspar was present as inclusions or wrapped by newly formed clay minerals to protect a further decomposition.

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The project was partially supported by the Fundamental Research Funds for the Central Universities” (No. 2652013037 and 2652013043).


[1] Sigmund, W.M., Bell, N.S., Bergström, L., 2000. Novel powder-processing methods for advanced ceramics. J. Am. Ceram.Soc., 83, 1557–1574.10.1111/j.1151-2916.2000.tb01432.xSearch in Google Scholar

[2] Yu, Z.W., Qi, X.P., Hu, X.P., Ma, Z., Liu, X.Y., 2001. Study on the development and utilization of powder quartz mines in Western. China Non-metallic Mining Industry Herald, 27, 17–18. In Chinese.Search in Google Scholar

[3] He, M.S., Li, M.X., 2003. Utilization status and development of non-metallic mines in Jiangxi Province. China Non-metallic Mining Industry Herald, 32, 52–54. In Chinese.Search in Google Scholar

[4] Guan, J.F., Mao, Y.L., Gao, H.M., Zhang, L.Y, Wu, L.J., Jing, Z.Q., Tang, H.W., 2007. The character and application foreground of natural fine quartz in Guiding Country, Guizhou Province. China Non-metallic Mining Industry Herald, 62, 54–55. In Chinese with English abstract.Search in Google Scholar

[5] Jing, Z., Ishida, E.H., Jin, F., Hashida, T., Yamasaki, N., 2006. Influence of quartz particle size on hydrothermal solidification of blast furnace slag. Ind. Eng. Chem. Res. 45, 7470–7474.10.1021/ie060461eSearch in Google Scholar

[6] Haus, R., Prinz, S., Priess, C., 2012. Assessment of high purity quartz resources. In Quartz: Deposits, Mineralogy and Analytics, J. Götze and R. Möckel (eds.), Springer-Verlag Berlin Heidelberg, 29–51.10.1007/978-3-642-22161-3_2Search in Google Scholar

[7] Hicyilmaz, C., Ulusoy, U., Yekeler, M., 2003. Effects of the shape properties of talc and quartz particles on the wettability based separation processes. Applied Surface Science 233, 204–212.10.1016/j.apsusc.2004.03.209Search in Google Scholar

[8] Sayilgan, A., Arol, A. I., 2004. Effect of carbonate alkalinity on flotation behavior of quartz. Int. J. Miner. Process 74, 233–238.10.1016/j.minpro.2003.12.002Search in Google Scholar

[9] Sekulic, Z., Canic, N., Bartulovic, Z., Dakovic, A., 2004. Application of different collectors in flotation concentration of feldspar, mica and quartz sand. Minerals Engineering 17, 77–80.10.1016/j.mineng.2003.10.004Search in Google Scholar

[10] Wang, Y. H., Ren, J. W., 2005. The flotation of quartz from iron minerals with a combined quaternary ammonium salt. Int. J. Miner. Process 77, 116–122.10.1016/j.minpro.2005.03.001Search in Google Scholar

[11] Mowla, D., Karimi, G., Ostadnezhad, K., 2008. Removal of hematite from silica sand ore by reverse flotation technique. Separation and Purification Technology 58, 419–423.10.1016/j.seppur.2007.08.023Search in Google Scholar

[12] Ruey, L. U., Shiuh, J. J., Chia, C. W., Sahayam, A. C, 2005. Microwave-Assisted Volatilization of silicon fluorides for the determination of trace impurities in high purity silicon powder and quartz by ICP-MS. Analytica Chimica Acta 536, 295–299.10.1016/j.aca.2004.12.040Search in Google Scholar

[13] Štyriaková, I., Mockovčiaková, A., Štyriak, I., Kraus, I., Uhlík, P., Madejová, J., Orolínová, Z., 2012. Bioleaching of clays and iron oxide coatings from quartz sands. Applied Clay Science 61, 1–7.10.1016/j.clay.2012.02.020Search in Google Scholar

[14] Sokolnikova, J.V., Vasilyeva, I.E., Menshikov, V.I., 2003. Determination of trace alkaline metals in quartz by flame atomic emission and atomic absorption spectrometry. Spectrochimica Acta Part B, 58, 387–391.10.1016/S0584-8547(02)00153-2Search in Google Scholar

[15] Lu, Y., Yin, H., Zhang, W., Chen, W., 2008. Geologic survey of the powder quartz deposit in Yunnan, 88 pages, Internal report. In Chinese.Search in Google Scholar

[16] Hasegawa, M., Kimata, M., Shimane, M., Shoji, T., Tsuruta, M., 2001. The effect of liquid additives on dry ultrafine grinding of quartz. Powder Technology 114, 145–151.10.1016/S0032-5910(00)00290-4Search in Google Scholar

[17] Mohammadnejad, S., Provis, J.L., van Deventer, J.S.J., 2013. Effects of grinding on the preg-robbing potential of quartz in an acidic chloride medium. Minerals Engineering 52, 31–37.10.1016/j.mineng.2013.03.003Search in Google Scholar

[18] Dash, K., Thangavel, S., Dhavile, S.M., Chandrasekaran, K., Chaurasia, S.C., 2003. Multichannel vapor phase digestion (MCVPD) of high purity quartz powder and the determination of trace impurities by ICP-AES and ICP-MS. Atomic Spectroscopy 24, 143–148.Search in Google Scholar

[19] Götze, J., 2012. Classification, mineralogy and industrial potential of SiO2 minerals and rocks. In Quartz: Deposits, Mineralogy and Analytics, J. Götze and R. Möckel (eds.), Springer-Verlag Berlin Heidelberg, 1–27.10.1007/978-3-642-22161-3Search in Google Scholar

[20] Thomas, R., Davidson, P., Badanina, E., 2012. Water-and boron-rich melt inclusions in quartz from the Malkhan pegmatite, Transbaikalia, Russia. Minerals 2, 435–458.10.3390/min2040435Search in Google Scholar

Received: 2015-6-13
Accepted: 2016-4-12
Published Online: 2016-12-3
Published in Print: 2016-1-1

© 2016 Ran-Fang Zuo et al., published by De Gruyter Open

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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