text: Given that direct reduction is a chemical exchange between gas and solid, the fluidization of ore by reducing gases is an attractive line of research. However, the changing nature of the constituents, combined with the high temperature and the difficulty of controlling the fluidization phenomenon, make its adoption singularly difficult.
  Many processes have been developed on this principle. Some have been technical failures, such as the HIB (a single plant commissioned in 1972, converted to the Midrex in 1981) or economic failures, such as the FIOR process (a single plant commissioned in 1976, mothballed since 2001, the forerunner of FINMET).
  Developed in 1991 from the FIOR process, the FINMET process seems more mature, but its expansion has not materialized (two plants were built, and only one was in operation as of 2014). The CIRCORED process, also recent, is similarly stagnant (just one plant built, commissioned in 1999, mothballed in 2012), despite its adaptability to coal (CIRCOFER process, no industrial production).