Effect of minerals on the self-heating retorting of oil shale: Self-heating effect and shale-oil production

•The effect of minerals on the pyrolysis is studied under a special condition, i.e., self-heating retorting.•Different effects are observed between self-heating retorting and common retorting.•Using HF or HNO3 to treat oil shale promotes self-heating temperature, but using HCl markedly lower it.•Lowering self-heating temperature may not lower oil yield, but it favors the production of heavy components.•Despite different acid demineralizations, the oils mainly consist of various hydrocarbons. The effect of the minerals of Huadian oil shale on a low-energy input retorting route was studied. This special retorting route was achieved by a self-heating effect, that is, spontaneously increasing retorting temperature in the absence of external heat provision (Guo et al., 2013) [12]. Oil shale was first demineralized with HCl, HNO3 or HF before used in the self-heating retorting. The oil shales treated with different acids, and their corresponding semicokes attained after retorting were also characterized. The results showed that using HF-treated oil shale produces the best self-heating effect and the highest oil yield. Using HNO3-treated oil shale also promotes the self-heating effect. While using HCl-treated oil shale remarkably worsens the self-heating effect, but it gives a higher oil yield than using HNO3-treated or raw oil shale. The reasons are also analyzed. Although different acid treatments affect the self-heating effect differently, all the attained oils mainly consist of various hydrocarbons, however, the product distributions are different.