Characterization of New and Traditional Clay Products using Wrenshall, Springfield, and St. Cloud Area Clays

Abstract

Clays and clay minerals from Wrenshall, Springfield, and the St. Cloud area show potential for use as industrial minerals. The Wrenshall clays are Pleistocene glacial lake clays, the Springfield clays are Late Cretaceous non-marine and marine shales, and the St. Cloud area clays are primary and secondary kaolins and Late Cretaceous non-marine shales. This project includes a characterization of the physical properties of these clay raw materials and their finished products. Specialty bricks can be made from the Wrenshall clays using coloring additives, paint rock, taconite concentrate, and wild rice hulls as additives. Springfield non-marine shales can be used as fillers in a tile body to improve plasticity to the body. Springfield marine shales, which bloat upon firing, can be used as lightweight aggregate. The primary kaolins from the St. Cloud area are capable of being used as floor and wall tile and as a ceramic clay. The secondary kaolins can also be used for tile and ceramics, but sufficient quantities have not been found. The non-marine shales in the St. Cloud area (Avon) are currently being used for ceramic pieces. This project characterizes these clays and clay minerals based on evaluation of the shrinkage, absorption, and color of the fired products. These clay deposits can be used as industrial minerals for the products tested.