Environmental Toxicity Analysis and Reduction of Ceramsite Synthesis from Industrial Coal Gasification Coarse Cinder Waste

Coal gasification coarse cinder (CGCC) is the main waste in the coal gasification industry, containing low calorific value but high heavy metal residuals. To achieve environmental toxicity stabilization and waste recycling, we developed a manufacturing method of multiple-functional ceramsite from CGCC by pelletizing and sintering. By altering key parameters during the manufacturing process (including CGCC content, sintering temperature, and time), the physical properties and leaching toxicity of ceramsite were evaluated. Sintering temperature was identified with a significantly positive relationship with ceramsite's compressive strength, whereas CGCC content was negatively correlated with water adsorption. The highest compressive strength (24.00 MPa) and relatively lower water absorption (21.36%) was achieved at 50% CGCC content and 1,150 degrees C sintering for 30 min. The toxicity tests showed acceptable leaching heavy metals with minimal environmental impact. Considering the energy conservation and the maximal recycling of CGCC, optimal ceramsite manufacturing is suggested as 50% CGCC content and 1,150 degrees C/10 min sintering temperature/time. Our results indicated that multiple-functional ceramsite manufacturing is a low-cost and environmentally friendly approach for CGCC recycling.