Quartz for the Chemical Industry

The widespread use of quartz in the chemical industry stems both from its being a pure silicon source and from its chemical durability. Apart from hydrofluoric acid and hot concentrated alkaline solutions, it is resistant to acids and to most industrial chemicals; it does not react and does not release ions into the medium. With a Mohs hardness of 7, a density of 2.65 g/cm³ and a melting point of 1710°C, this mineral keeps its form both at high temperature and in aggressive chemical environments. These properties make quartz usable both as a raw material and as a process material.

The production of sodium silicate, silica gel, precipitated silica and colloidal silica all begins with quartz-sourced silica. In the production of silicon carbide, ferrosilicon and metallic silicon, quartz is processed by reduction at high temperature together with a carbon source. In the production of zeolites, catalyst carriers and synthetic silicates, the purity of the quartz affects the pore structure and the activity of the finished product. Each of these processes calls for a silica source in which the iron, aluminum and alkali contents are kept under control.

Besides its use as a raw material, quartz is also employed as a process material in chemical plants. It is used as inert packing in absorption and neutralization columns, as a support layer in catalyst beds and as bed material in acid lines; both mechanical strength and non-reactivity are sought in these applications. Medium and coarse granular fractions such as 0.7-1.2 mm are generally preferred in column and reactor applications, while micronized quartz is used in filler and coating chemicals. The fraction is selected according to column geometry, flow rate and pressure drop targets.