How to Purify Quartz Associated with Kaolinite?

The comprehensive utilization of quartz associated with kaolinite can effectively alleviate the problem of tailings accumulation in kaolinite production. This quartz exhibits characteristics such as high impurity content, complex mineral composition, and low SiO₂ content. The primary challenge in its purification process lies in adopting economically viable methods to remove gangue minerals like kaolinite, mica, and feldspar, thereby further reducing impurity levels.

(1) Scouring-Classification

Scouring utilizes mechanical forces acting on quartz surfaces during rotation and abrasion between sand particles to effectively remove adhering minerals, clay-like impurities, and surface iron films. It also fractures unconsolidated mineral aggregates. Combined with classification, this achieves preliminary purification. The mechanical structure of the scrubber significantly impacts quartz sand cleaning efficiency, followed by scrubber speed, duration, and pulp concentration. For quartz accompanied by kaolinite, this process effectively removes adhered clay minerals like kaolinite and aggregates from the quartz surface while reducing surface iron film, achieving preliminary purification.

(2) Color Sorting

Color sorting utilizes the differences in photoelectric properties between quartz sand and gangue minerals for separation. However, it is limited by particle size, with sorting effectiveness varying across different grain sizes. Coarser particles yield better results, while finer particles perform less effectively. Color sorting can efficiently remove discolored particles prior to processing and classify quartz into different grades, preventing cross-contamination between grades during subsequent mineral processing stages. Quartz associated with kaolinite often contains gangue minerals and aggregates of varying colors. Color sorting can effectively separate these discolored particles, but it may also remove some quartz.

(3) Grinding and Classification

Grinding reduces coarse quartz particles to finer sizes while simultaneously liberating quartz and gangue minerals into individual grains. Common grinding methods include ball milling, rod milling, and agitation milling, each emphasizing different grinding effects. These typically require grinding media such as iron balls or zirconium balls for ball milling. Milled minerals are typically classified to screen out the required particle sizes and remove fines generated during grinding.

(4) Magnetic Separation and Flotation

Magnetic separation utilizes differences in mineral magnetic properties for sorting. Kaolinite-associated quartz often contains biotite and iron-bearing magnetic materials, which can be removed using strong magnetic separators and high-gradient magnetic separators. Flotation separates minerals based on differences in hydrophobic properties. Quartz associated with kaolinite often contains significant amounts of silicate minerals like mica and feldspar, which are typically separated and removed via flotation. Mica and feldspar are commonly removed using multi-stage reverse flotation. Leveraging the potential difference between mica and quartz, amine collectors are typically employed to remove mica through multi-stage flotation under acid washing conditions.

(5) Acid Leaching

Acid leaching serves as a method for deep purification of quartz. Leveraging quartz's chemically stable nature and its insolubility in acids other than hydrofluoric acid, various acid solutions are formulated to leach impurities from gangue minerals within quartz under specific solid-liquid ratios and temperatures.