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

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.