Abstract: A method of calcining solid materials on a downdraught travelling grate prior to treatment at a higher temperature on a continuously operating kiln, wherein heat for said calcining is obtained by drawings hot gaseous effluent from the kiln into the travelling grate through the solids discharge outlet thereof, characterized in that additional heat from an auxiliary source is induced into a downstream portion of the travelling grate.

Abstract: Waste matter is incinerated in a combustion zone external to a rotary cement kiln. The resulting gaseous product is taken up in effluent gas from the cement making process in contact with calcareous material. At least some of the combustion zone bottom ash is combined in the eventual standard Portland cement by firing it in the kiln with the clinker-forming materials. The combustion zone can for instance be a fluidized bed combustor. The combustion zone can be a zone through which the clinker-forming materials pass at a temperature such that the waste matter ignites.

Abstract: A method of utilizing waste heat from a fuel-fired electrical power generation or steam raising plant, wherein flue gas from said plant is conducted through a heat exchange zone in contact with relatively cool wet material for making Portland cement.

Abstract: A process in which a substance undergoes endothermic change within a predetermined temperature range in at least one stage of the process and is subsequently subjected to a substantially higher temperature in a further stage of the process, characterised in that effluent heat from said further stage is augmented and the resultant supply of heat is applied partly to the generation of power, and partly to said endothermic change.