To produce 4N grade high-purity silica powder from natural ore, the mineralogical characteristics of natural silica ore were investigated and their effects on the purification process were revealed. The Chinese silica mineral ore used was composed of iron and aluminum as main impurities and calcium, magnesium, potassium, sodium, and titanium as trace impurities; these trace impurities generally exist as either single oxides or complex oxides. It was confirmed that liberation and acidic washing of the impurities were highly dependent on the particle size of the ground silica ore and on its mineralogical characteristics such as the distribution and phases of existing impurities. It is suggested that appropriate size reduction of silica ore should be realized for optimized purification according to the origin of the natural silica ore. A single step purification process, the mechano-chemical washing (MCW) process, was proposed and verified in comparison with the conventional multi step washing process.

1. Introduction
 2. Experimental procedure
  2.1 Raw materials
  2.2 Sample preparation
  2.3 Acid Washing
  2.4 Analysis
 3. Results and Discussion
  3.1 Effect of particle size on impurity liberation
  3.2 Distribution and phase of impurity
  3.3 Effect of acidic washing solution
  3.4 Mechano-chemical acidic washing
 4. Conclusions
 Acknowledgment
 References

• Jesik Park(School of Materials Science and Engineering, Kumoh National Institute of Technology, 61 Daehak-ro, Gumi-si, Gyeongsangbuk-do 39177, Republic of Korea)
• Churl Kyoung Lee(School of Materials Science and Engineering, Kumoh National Institute of Technology, 61 Daehak-ro, Gumi-si, Gyeongsangbuk-do 39177, Republic of Korea)
• Hyun-Kwon Lee(School of Materials Science and Engineering, Kumoh National Institute of Technology, 61 Daehak-ro, Gumi-si, Gyeongsangbuk-do 39177, Republic of Korea)