Effect of Accumulated Lime‐Softening Slurry on Magnesium Reduction

Abstract

This article discusses an example of reducing magnesium by lime‐softening in the Meramec River water source in the presence of accumulated softening slurry, to an amount that will not precipitate in 140°F domestic hot water heaters and will not require recarbonation. The lime dose for this purpose should not exceed the raw‐water alkalinity equivalent plus 34.24 ppm. The slurry concentration for contacting should be about 5 per cent by weight and should be from softening products only, being virtually free of activated silica, coagulant, and turbidity. If large amounts of magnesium solids are accumulated in the slurry, and are not removed with the effluent water, the slurry becomes less effective as a softening aid. Mixing and contacting time for the softening reactions should be about 30 min.