Ceramsite is made of shale, clay, gangue, fly ash and other inorganic materials as the main raw material, by the ingredients, granulation into pellet, high temperature firing, and is one of silicate products with a certain strength and the bulk density is more than 900kg / m³. Ceramsite is low density, light weight, low water absorption, and has good thermal insulation, anti-seismic, anti-frost and corrosion resistance properties. Ceramsite is widely used in construction industry, environmental protection industry, chemical industry and horticultural industry and other industries. In the construction application, ceramsite is divided into ultra-light ceramic ceramsite, ordinary ceramsite and high-strength ceramsite according to the density grade.

There are two stages of the development of sludge ceramsite industry.

First, the basic theoretical research

This stage is mainly undertaken by the environmental engineering major of higher professional institutions, and the content is mainly including burning mechanism, proportioning test, firing regime, product performance of sludge ceramsite. The research of this stage basically formed the basic theory system of adding the sludge burning to the ceramsite, and draw the following conclusion:

(1) the main components of sludge is SiO₂, Al₂O₃ and other oxides and organic matter, in which SiO₂, Al₂O₃ and the base material sintered together to provide structural strength skeleton, and the decomposition of organic matter in the firing process of gas, resulting in ceramsite expansion, to reduce the ceramsite density.

(2) the calcination temperature of ceramsite is about 1200 degrees centigrade, and the organic matter in sludge is decomposed, and the pathogen and parasite are killed by high temperature, and the harmful heavy metal is melted in ceramsite under high temperature, and the leaching toxicity accords with "Soil Environmental Quality Standards " in the agricultural land of heavy metal pollutants control standard value requirements. The disposal of the sludge is complete, and is harmless to the environment, and it will not affect the use performance of ceramsite products.

Second, the ceramsite production process technology

To further systematic research of pretreatment technology, deodorant technology, matching technology, firing technology and flue gas treatment technology and other systems and equipment that high sodium content of sludge ceramsite raw material.

The two stages of research, is the basic formation of basic theory production technology theory system about production of blending sludge into ceramsite, and gradually promoting to application in the sludge ceramsite industry.