The Superior plant, located on the Lake Superior waterfront in Wisconsin, is ideally positioned to service the upper Midwestern states and Central Canada.
Limestone is not quarried at this site; it comes from quarries in Michigan and is transported by self-unloading bulk freighters to the Superior dock in Wisconsin. Finished product is shipped out by truck and rail, often providing return loads for overland carriers who have dropped off commodities for shipping out of the port.
The newest addition to the plant is kiln #5, a state of the art high efficiency preheater lime kiln.
Graymont Superior has storage capacity allowing for 500,000 short tons of limestone to be stockpiled over 10 acres. Specialized equipment is required to handle this volume of raw material, including a massive man-trolley bridge crane that picks up limestone from anywhere within the storage area and transports it to conveyors feeding the rotary kilns. Large silos on the Superior site hold 10,000 short tons of finished lime. This inventory helps the Superior Plant meet fluctuations in customer demand.
Three types of limestone are calcined at the Superior facility to produce high calcium quicklime, high calcium hydrated lime, dolomitic quicklime and PCC quicklime.
In addition to calcined lime products, the plant is also a major supplier of finely ground limestone for various mining and manufacturing processes throughout the Midwest.
History of the Superior Plant:
The Graymont Superior plant was originally a lumber and cement supplier to the Duluth/Superior region, named Cutler-Gilbert-Pearson Company, formed in 1880. The company was sold to C. H. Graves Company in 1882, which added salt to the product line.
In 1912 the company began producing lime in Duluth, MN, and in 1914 the name was officially changed to Cutler-Magner Company. Over the years, the company expanded its enterprise to encompass production of cement, salt and lime at two production locations, Duluth and Superior.
Today: The Superior lime facility is called the Graymont Superior Plant, and the Duluth salt operation is North American Salt.