Intermediate Heat Zone:  The intermediate section is the zone directly above the fluid bed.  Two (2) radiant U-tubes extend through this section over the top surface of the fluidized bed.  Soil particles are thrown out of the fluid bed by gas bubbles which migrate through bed of material.  These particles mix around and contact the U-tubes.  The radiant U-tubes in this section contribute to heat input by radiant heating and conductive heating of the particles that contact the U-tubes.

Quieting Chamber:  The quieting chamber (gas room) is the uppermost section of the calcine chamber.  Dust will be found moving slowly with the gas stream.  The shape of this section reduces gas/dust velocity to minimize dust loading downstream.  Two (2) radiant U-tubes are placed in this section.  These U-tubes will maintain and slightly elevate the temperature of the gas stream to aid vaporization of mercury contained in dusts, prior to their exit from the calcine chamber.

Refractory:  The calcine chamber was constructed with an abrasion resistant refractory lining, which will resist the abrasive action of the soil impacting the walls.  The life expectancy of the refractory lining will vary depending on a variety of factors, among them: the inherent resistance of the lining itself, the abrasive characteristics of the soil, the number of times the chamber is allowed to cool off and restarted, etc.

The calcine chamber contains three different types of refractory:  1. HW 32-71 insulating fireclay castable refractory.  This insulating castable refractory is used in the floor of the chamber, up to the ledge which the steel plate rests on.  2. ALKAGUN® fireclay gunned refractory.  This gunned refractory is used from the ledge up to and including the cover.  Between the steel shell and the gunned-on refractory is 2" of board insulation, K-FAC-19®.  3.  Anchor-Loc® Ceramic Fiber Insulating Modules.  This insulating block refractory is used only in the upper hinged door of the chamber, as it is lightweight.  All of the above refractories are secured to the shell using stainless steel anchors.  The HW 32-71 and AKLAGUN refractories contain stainless steel needles for additional resistance to spalling.