Abstract: Low soluble arsenic diatomite filter aids and method of making such filter aids are disclosed. Alumina and/or aluminum hydroxide (ATH) are used as additives when preparing the filter aids, which may be straight-calcined or flux-calcined. Alternatively, activated alumina may be added to an already straight-calcined or flux-calcined diatomite filter aid. As compared to either straight-calcined or soda ash flux-calcined diatomite filter aids of similar permeabilities made from the same ore, the disclosed filter aids have lower soluble arsenic content. The disclosed filter aids have a soluble arsenic content, either by the OIV, EBC or USFCC method, of about 60% or less than the straight or flux-calcined diatomite filter aids of similar permeability without an alumina or ATH additive.

Abstract: Processes for manufacturing low soluble iron diatomite filter aids and such filter aids are disclosed. Aluminum oxide and/or aluminum hydroxide are used as additives when preparing the flux-calcined diatomite filter aids. As compared to either straight-calcined or soda ash flux-calcined diatomite filter aids of similar permeabilities made from the same ore, the disclosed filter aids have lower soluble iron levels. For instance, disclosed filter aids of about 0.5 to about 2.0 Darcy were made using either an aluminum oxide or aluminum hydroxide additive with soda ash. The disclosed filter aids may have an EBC soluble iron content of less than 80 ppm versus 130 ppm for similar filter aids that were made from the same ore and flux-calcined with just soda ash.