The use of zircon (ZrSiO4) as an opacifier glaze is now common in the sanitaryware and tile industries, with ceramics accounting for 56% of the 1.3m. tpa global zircon market.
To achieve the best results in opacity and whiteness in the glaze it is important that the size and shape of the zircon particles are closely controlled. Zircon flour, typically at a particle size below 45µm, as well as micronised zircon sand at a fineness below 6µm, are today used as opacifiers. However, to meet today’s market demands micronised grades are by far the preferred grades as they can be used directly in the glaze.
For all the micronised grades the average particle size, known as the D50 value, is the determining factor for the quality and grades from D50 = 0.8µm to 1.5µm are commercially available and in use today. ...