Method of operating a rotary furnace for the production of hydraulic binder so as to reduce ring formation therein, whereby the longitudinal temperature profile in the furnace is varied during furnace operation by injecting at least one fluid other than the main fuel(s), the primary oxidizer and hot air from the material cooler with at least one continuously or discontinuously varying injection parameter.

A method for the manufacture of a high alumina hydraulic binder comprising hydrating a source of aluminium ions with a source of calcium ions in the presence of water to form mineral hydrates and subsequently heating said mineral hydrates to form said high alumina hydraulic binder.

Method of operating a rotary furnace for the production of hydraulic binder so as to reduce ring formation therein, whereby the longitudinal temperature profile in the furnace is varied during furnace operation by injecting at least one fluid other than the main fuel(s) the primary oxidizer and hot air from the material cooler with at least one continuously or discontinuously varying injection parameter.