In the first half of the rotary kiln, the organic fractions of shale or shale stone are combusted, releasing significant heat, and forming the cellular structure required for the low density lightweight aggregate. Nearly 85 percent of the thermal energy required for the process is provided by the organic fraction of shale. In the second half of the kiln, the pellets are heat hardened by exposure to high-temperature gases (1150-1350°c) from the upstream combustion. This atmosphere creates the conditions necessary for the pellet sintering, creating the high-strength properties necessary for construction applications.

Shale ceramsite is also called high tensile ceramsite which is made of  shale or slate through crushing screening, or after grinding into a ball then burned expansion and become products, those particle size above 5 mm and light coarse aggregate are called shale ceramsite; those particle size less than 5 mm and light fine aggregate are called shale ceramic sand. 
According to process methods shale ceramsite are classified into ordinary shale ceramsite which made through crushing, screening, and burned expansion and round ball shale ceramsite made through grinding, ball pressing and burned expansion. 
Usage: 

Shale ceramsite is at present a kind of energy saving material, with the characters of light volume, high compressive strength, low thermal conductivity, no radiation, corrosion resisting, low bibulous rate, sound insulation, heat preservation, fire-resistant, antifreeze and corrosion resistant. 400 and 500 class super light shale ceramsite are suitable for structure insulation concrete, 600 to 900 level ones are used for main structure concrete and also can be used for in situ concrete floor mat layer, high-rise building external wall, shear wall, elevator room wall, roof insulation, find slope and aboard live roof. It is widely used among ship building, bridge engineering, kiln project, BOT TOT OT and oil-field engineering and also the most ideal material to produce space truss lightweight partition board, roof insulation board, hollow block, acoustical tile and not to finalize the design refractory pouring. In recent years its application way is expanding and is using among thermal equipment, heat preservation library, highway, soilless culture greening and so on.