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