Rare earth elements are a group of seventeen chemical elements that occur together in the periodic table (see image). The group consists of yttrium and the 15 lanthanide elements (lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium).
Uses include catalysts (55%), metallurgy/alloys, ceramics/glass, glass polishing, etc. Most computer, cell phone, and electric vehicle batteries are made with rare earth metals. The demand for rare earth elements has grown rapidly, but their occurrence in minable deposits is limited. While rotary kilns are used in their beneficiation the scale is currently restricted to indirect fired rotary kilns. However, this could be further investigated with potential clients.
Nickel, direct reduction iron (DRI), and other metals reduction processes can be performed in direct-fired rotary kilns. Zinc recovery from metallurgical waste such as lead blast furnace (LBF), Electric Arc Furnace (EAF) dust, etc. is current metal recycle process that is equally attractive (Mintek)and uses the rotary kiln (Waelz kiln) with short L/D.