2015-9-10 · Fire Clay -Figure 11.25-4 illustrates the process flow for fire clay processing. Mined fire clay first istransported to the processing plant and stockpiled. In some cases, the crude clay is weathered for 6 to12 months, depending on the type of fire clay. Freezing and thawing break the material up, resultingin smaller particles and improved plasticity. The material then is crushed and ground. At this stage inthe process, the clay has a moisture content of 10 to 15 percent. For certain applications, the clay isdried in mechanical dryers to reduce the moisture content of the material to 7 percent or less.Typically, rotary and vibrating grate dryers fired with natural gas or fuel oil are used for drying fireclay.