| abstract |
A method of cement and sulphuric acid production by the Muller-Kuhne process involves decomposing CaSO4 in a mixture of residues and cement starting material powder and/or chemically reactive carbon in a rotary kiln, firing the CaO at above 1200 deg C in the presence of SiO2, Al2O3 and Fe2O3 to form cement and reacting the SO2-containing flue gas to form SO3 or H2SO4. The novelty is that dry gypsum board and other gypsum rubble are pre-reduced to a uniform mill-processable edge length, sorted and freed from foreign materials such as wood, steel and plastic pieces, ground to powder fineness under throttled air suction, mixed with other cement starting material powder components and, after optional intermediate storage, processed in the rotary kiln while supplying tertiary air. Also claimed is a plant for carrying out the above method. |