Calcite/Limestone

Limestone is a naturally occurring rock that is crushed & processed to produce a uniform granular material which when used in properly designed limestone contactors will allow the pH of finished water to be in the range of 7.2-8.3.

Limestone contactors are typically placed after filtration, primary disinfection & chlorine contact. With a limestone contactor, there is no chemical feed facility to maintain and no concern for over-feeding a chemical such as caustic soda.

KALIMATI® limestone complies with ASTM Standard C51-02 as “sedimentary rock consisting of mainly carbonate & containing no more than 0-5% magnesium carbonate”.

Uses of Limestone:

Acid rain: The neutralization of acid lake water.
Agriculture: Soil stabilization and pH control.
Air quality: Neutralizes sulfur dioxide gases from industrial processes such as smelting metal ores and coal-fired generating stations.
Aluminium
Aggregate for concrete and road building.
Artificial Waterfalls.
Water treatment-drinking water clarification.

Design Conditions:

Limestone contactors must be designed to treat the maximum flow of the plant.
EBCT (Empty Bed Contact Time) is in the range of 20 to 40 minutes if water is less than 5 °C, otherwise, B EBCT in the range of 15 minutes to 1 hour have been used in successful contactor design.
The water to be treated with a limestone contactor must have low iron and turbidity content.
A water system should have a pH < 7.2, calcium < 60 mg/L and alkalinity < 100 mg/L.
A special contactor design is required if the iron content is more than 0.2 mg/L & manganese content is more than is 0.05 mg/L.

This is due to possibility of the iron and manganese coating the contactor, and slows the calcium carbonate dissolution