Importance of Slaking Temperature

Lime consumption is directly related to slurry reactivity which in turn is tied to the slaking process itself - when you manage slaking properly you will use less quicklime.

Slaking temperature has long been understood to be the most influential factor in preparing highly reactive lime slurry. The theory is, that the hotter the temperature is when the reaction takes place, the smaller the hydrated lime particles are that are created, with more surface area and more porosity. More surface area and porosity means quicker dissolution and more available hydroxl ions for the neutralization reaction to take place in a given time period.

Not satisfied with theory alone, our optimization specialists devised an experiment to show exactly how important slaking temperature is to lime reactivity and lime consumption. The results of which are displayed in the following two charts:

Lime slurry prepared at an incoming water temperature of 25 oC (85 oC slaking temperature) produced a slurry with very fine (small) hydrated lime particles, with high surface area, and was able to neutralize a known acid from pH ~2 to ph ~10 in approximately 9 minutes.

Lime slurry prepared with at a lower incoming water temperature of 5 oC (65 oC slaking temperature) produced a slurry with relatively coarse (large) hydrated lime particles, with low surface area, and required 17% more quicklime to neutralize the same acid, and took more than twice as long to reach the same pH (20 minutes vs 9 minutes).