DESCRIPTION

Diatomaceous Earth occurs as a powder of varying colors consisting of processed siliceous skeletons of diatoms. The natural powder (gray to off-white) is air dried and classified by particle size; the calcined powder (pink to buff-colored) is air dried, classified, calcined with or without the addition of a modifier such as perlite or low levels of flux (as used in flux-calcined powder) at a high temperature (815°–982°), and again classified; the flux-calcined powder (white) is air dried, classified, calcined in the presence of a suitable flux (generally soda ash or other alkaline salt), and again classified; the acid-washed powder is any of the preceding powders having been further purified by washing in acid and rinsing with water; and the functionally coated powder is any of the preceding powders treated with silicon dioxide—a substance used as an adsorbent or absorbent in food processing. It is insoluble in water, in acids (except hydrofluoric), and in dilute alkalis.