Different residues of Huadian oil shale processing were investigated. Their inorganic chemical composition and phase structural characteristics were identified by X-ray fluorescence spectrometry (XRF) and X-ray diffractometry (XRD). The influence of calcination conditions on processing residues at different ash activation degrees and impurities' leaching rates as well as the quality of obtained SiO2 concentrate were investigated by a single-factor method. The results showed that only circular crossflow-type retorting-derived semicoke has different phase-structural characteristics at different calcination temperatures. In the range of 700–800 °C, the leaching rate of aluminum and iron reaches the maximum. To prepare SiO2 concentrate, starting material should be calcined for 1.5 h at 700–800 °C. As a result, SiO2 concentrate which meets the national standard of silica white will be obtained; the content of SiO2 is 92.34% and its specific surface area 104 m2/g. Phase structures of Fushun-type retorting residue and cogeneration power plant ash did not change dramatically at different calcination temperatures. The leaching rate of Al and Fe reached the maximum. Further calcination is unnecessary in reutilization, only removal of impurities by means of acid soaker is relevant. Fushun-type retorting residue can also be used to make SiO2 concentrate which meets the national standard; the content of SiO2 is 90.38%, its specific surface area is 91 m2/g. The leaching rate of aluminum from cogeneration power plant ash is lower, and this ash cannot be used to prepare silica white meeting the national standard. It can be applied as an ingredient of cement, at brick preparation, etc. Separation and purification products are a mixture of crystalline SiO2 and amorphous SiO2, while the content of crystalline SiO2 is 32.2%.
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