Abstract: Disclosed is a process for removing acidic impurities from off-gases generated in the retorting of oil shale comprising contacting a rubblized mass of oil shale which has been substantially depleted in hydrocarbonaceous materials with water, so as to extract basic components from the mass; and contacting off-gases, which were generated during the retorting of oil shale and which contain acidic impurities, with the water containing basic components so as to substantially remove said acidic impurities from said off-gases.

Abstract: Removal of molten slag from combustion chambers for combustion of combustible gases containing entrained slag-forming particulates, is frequently a problem since the slag tends to solidify in the tap-hole resulting in bridging and eventual pluggage of the tap-hole. This invention eliminates this problem by providing a dam around the periphery of the tap-hole of sufficient height to maintain a pool of molten slag on the inclined bottom of the combustion chamber to a depth whereby said slag pool is an effective heat sink to maintain the molten slag in flowable condition, and by providing in the dam at least one inclined drain trough which over-hangs the tap-hole a sufficient distance to minimize contact of draining slag with the walls of the tap-hole.

Abstract: Temperature control is often a problem in direct-fired rotary kilns for the pyrolysis of carbonaceous materials wherein at least part of the thermal energy for pyrolysis is obtained by in situ combustion of the pyrolysis gases. The present process and apparatus provides a means by which temperature control, and particularly reduction in intensity of the fireball at the burner end of the kiln and/or moving the fireball away from the burner hood. This is accomplished by (1) controlling the velocity of any burner gases and the velocity of the in situ air (or other oxygen-containing gas) and (2) the distribution of the in situ air at the burner end of the kiln, such that a Craya-Curtet number of at least 0.2, and preferably at least 0.4, is obtained.