Abstract: Porous granules that contain separate particles of alkali metal silicate and zeolite are stable and are efficient ion exchangers in aqueous effluents and/or solutions. Said granules are heated to provide the stability required so that even though some silicate may dissolve when the granules are exposed to water, the zeolite does not disperse throughout the water.

Abstract: Amorphous, hydrated magnesium silicate is effective in reducing the concentration of various metal ions in aqueous solutions or effluent streams. Both mono- and multi-valent ions can be treated in this manner thereby providing a method of preventing release of metal ions to the environment. The method is especially efficient in removal of chrome values from effluents generated in chrome tanning operations. Efficient adsorption of the chrome requires that the pH of the effluent-magnesium silicate slurry be adjusted to or maintained at a value between 5.3 and 9.8. The chrome value may be recovered from the magnesium silicate by acidification of the complex.

Abstract: The recycle stream from chrome tanning baths can be treated with magnesium silicate to reduce the amount of suspended solids. The treated stream can be recycled more times, thereby providing a considerable savings of chrome values.