Drive-Through Silos Ideal for Chemical-Grade Limestone

At its Crab Orchard, TN, facility, Franklin Industrial Minerals specializes in the mining and processing of high-purity, chemical-grade limestone into coarse-, medium-, or ground-sized aggregate. This facility joins the company’s seven other mining and processing facilities in the United States, that together offer hundreds of high-quality products with a worldwide distribution.

The Crab Orchard facility features an underground mine that utilizes room and pillar mining methods and is developed with the help of computer aided design (CAD). The average room height is 30–60 ft and mineral reserves are in excess of 50 years. The mine is dry and is utilized to store highly seasonal, high-volume products, such as fertilizer filler.

Crushing, grinding, and milling equipment includes five roller mills and has the capability to produce specialized and closely sized products, or a variety of blends. The high-quality products are available in bulk or bag, and sometimes semibulk. The processing plant is specifically designed to produce chemical-grade raw materials, as well as fine ground filler and extenders.

When the company began a project at its Crab Orchard plant in spring 2008 that would allow it to process chemical-grade limestone into a very fine limestone ground powder (90% by volume passes through a 325 mesh screen), the company recognized its need for additional storage to accommodate the new product.

“We needed two large storage silos—much larger than our typical silos—that would suit both our plant and product specifications and could be delivered at an economical cost,” said Gary Hankins, project engineer for Franklin Industrial Minerals.

After visiting another local plant that featured a Columbian TecTank silo that had worked with no problems for more than 10 years, the company approached the tank manufacturer for solutions to its storage challenge.

“The silos we proposed were 32 × 112 ft and featured a drive-through design that would allow for loading of both trucks and railcars, which were the two principal methods of transport from this facility,” said Crystal Riley, sales representative for Columbian TecTank in Parsons, KS.

Construction of the Columbian TecTank silos began in May 2008 and the first silo was filled in late October. The unloading system was operational a few weeks later. Both silos have a truck load-out system in place that ships up to 500 tn/day. Two rail load-outs are planned to be on-line in early fall 2009.

“The drive-through design was key for us,” said Hankins. “This new project requires a significant amount of storage and the ability to move our product efficiently. We feel the tanks from Columbian TecTank allow us to do that.”

Franklin owns and operates eight mineral mining and processing locations across the southeastern and southwestern United States. They supply hundreds of quality products to thousands of customers in more than 20 major industrial and agricultural markets. Principally known as a major producer of chemical-grade high-purity limestone, other minerals produced include alumina trihydrate and crushed stone. Franklin products are readily available in bulk, semibulk, and bagged quantities, and are sold through both direct sales and an extensive worldwide distributor network.

Columbian TecTank tanks are specially designed for simple, quick, and safe installation, ensuring value and quick turnaround. All tanks are produced at ISO-certified facilities in Kansas and Tennessee. For more information, visit www.columbiantectank.com. For more information on Franklin Industrial Minerals, visit www.frankmin.com.