Chemical leaching

Chemical refining is one of the most efficient operations to reduce mineral impurities in high purity quartz. During acid treatment, medium to strong mineral acids are used at elevated temperatures. Usually hydrofluoric acid is applied, but a combination of several acids can be used (HF, HCl, HNO₃) to improve chemical purification results.

Connate minerals (e.g. feldspars, micas), difficult to liberate during physical processing, are dissolved in the course of leaching. Additional impurities, enriched in micro fissures and structural dislocations, can be removed by the enhanced dissolution of quartz. This kind of purification procedure is regularly applied in lamp tubing as well as semiconductor applications of high purity quartz.

Besides laboratory scale equipment, ANZAPLAN provides local test plant for the production of high purity quartz samples which allows production of up to 1,000 kg sample quantities. This plant also permits leaching of silica by hydrofluoric acid. All auxiliaries such as classifiers and drying equipment have been tuned to high-purity conditions so allowing the reliable processing of high-purity raw materials on a semi-technical scale.