By Jim Bloch
Cargill Salt, Inc. in St. Clair will erect a new silo in which to store soda ash, demolish the old silo, and build a new pump shed to house an existing mixing tank, pump and air compressor.
The St. Clair City Council unanimously approved the site plan for the project at its regular meeting March 18.
“Cargill Salt uses soda ash in a brine purification process to remove any calcium ions that may be present,” said Ben Slaton, Cargill’s builds project manager, in his scope-of-work narrative.
If Calcium ions are not removed, they can form salts that do not dissolve, reducing the amount of usable salt, which must be removed at the end of the manufacturing process.
“Cargill receives the soda ash in a bulk powder form via truck,” said Slaton.
The improvements include upgrading the dust collection system to maintain a clean environment as the soda ash is unloaded.
“The soda ash is then stored in a large silo and gradually fed to our clarifier unit to treat the brine,” said Slaton. “This process is essential to our operation and there is no substitute or alternative method.”
The brine is transferred to the Cargill site from a tank farm on Puttygut Road.
“We make a salt that is unique to St. Clair,” said Slaton at the planning commission meeting March 12, referring to Diamond Crystal Kosher Salt. “The treatment of the brine is proprietary, which is the critical first step in the process.”
The new silo will be more efficiently designed, allowing for better flow of the soda ash to the clarifier tank. It will be constructed from a low-carbon stainless steel, giving it a longer life than the current silo, and stand 51 feet tall, compared to 47 feet for the old silo.
“The steel on the current silo is showing signs of thinning and needs to be replaced,” said Slaton.
The old silo is an A.O. Smith Harvestore built in 1957 when the Diamond Crystal Salt Company, the predecessor of Cargill, switched from using 50-pound bags of soda ash to bulk storage. The silo, designed for grain storage, was adapted for receiving and storing bulk soda ash. The old silo sits on the east side of Second Street, outside Cargill’s fenced tank farm on the west side of the street, just north of Mary Street. A gravel containment berm runs between the tank farm, which contains four tanks and an outbuilding, and Second Street. The new silo and the pump shed will be built inside the fence, making the equipment more secure.
“By relocating the tank closer to the existing buildings, we can eliminate the need to pump (the soda ash slurry) under Second Street,” said Slaton. “Currently, the soda ash silo and a couple of conveyors are just out open to the public.”
The pump shed will cover 484 square feet and stand 17 feet tall. New process piping will be installed inside and outside the pump shed.
The council approved the project by a 6-0 vote; council member Kris Paul was absent.
Jim Bloch is a freelance writer based in St. Clair, Michigan. Contact him at bloch.jim@gmail.com.
