fact that, during calcination, the limestone remains stationary relative to the hearth. The vertical kiln has the lowest uncontrolled dust emissions due to the large lump feed, the relatively low air velocities, and the slow movement of material through the kiln. In coal-fired kilns, the Vertical Incinerator. Our durable, high-quality Vertical Incinerator solutions are designed to optimise your calcination processes. By recycling rotary kiln exhaust gases, our Vertical Incinerators are able to cut energy costs and harmful emissions, while maximising steam production. Traditionally, calcinating raw materials comes at a steep price.