Abstract: A diatomaceous earth product with low crystalline silica content after at least one calcination step of between about 927° C. (1700° F.) and about 1149° C. (2100° F.) is disclosed. The product comprises natural diatomaceous earth and at least one binding agent comprising potassium silicate. Further the product comprises no more than about 4.0 wt % of crystalline silica and has a permeability in the range of about 0.3 darcy to greater than about 20 darcy. A process for making such diatomaceous earth product with a low crystalline silica content is disclosed. Moreover, a diatomaceous earth filter aid comprising such a diatomaceous earth product is disclosed.

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.

Abstract: A process for manufacturing low soluble iron, medium flow rate diatomite filter aids and such filter aids are disclosed. Sodium aluminate is used as an additive. 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 much lower iron solubilities. For instance, disclosed filter aids of about 0.3 to about 2.0 Darcy were made using an alkali aluminate as an additive/flux agent to have an EBC soluble iron content of less than 100 ppm versus more than 140 ppm for similar filter aids that were made from the same ore and flux-calcined with soda ash.

Abstract: A diatomaceous earth product with low crystalline silica content after at least one calcination step of between about 927° C. (1700° F.) and about 1149° C. (2100° F.) is disclosed. The product comprises natural diatomaceous earth and at least one binding agent comprising potassium silicate. Further the product comprises no more than about 4.0 wt % of crystalline silica and has a permeability in the range of about 0.3 darcy to greater than about 20 darcy. A process for making such diatomaceous earth product with a low crystalline silica content is disclosed. Moreover, a diatomaceous earth filter aid comprising such a diatomaceous earth product is disclosed.