Abstract: The present invention relates to processes for producing a material usable as a suitable civil engineering and construction material by treating a combustion ash formed by the combustion of a fluidized bed comprising a coal as the fuel and limestone as a desulfurizing agent. In this process, quick lime contained therein is sufficiently slaked at first by addition of water and heat thus generated is released to prevent disintegration of the product, and then the product is subjected to atmospheric pressure steam treatment to obtain a product of high strength in a short time.

Abstract: A plant for manufacturing cement clinker is constituted by the following portions: a suspension preheater for preheating a cement material powder; a spouted-bed type furnace for granulating the preheated cement material powder; a fluidized-bed type furnace for sintering the granulated cement material powder; a cooling system for cooling the granulated and burned product; a plurality of burners disposed at a lower portion of the spouter-bed type furnace so as to oppose to one another such that their ends are directed obliquely upward and direct streams of fuel to converge on a central axis of the spouted bed, thereby to form a local hot region in the spouted bed; a preheated material charging chute disposed slightly above the local hot region and adapted for charging the preheated material powder from the suspension preheater into the spouted-bed type furnace; and a granulated material discharging chute provided on one side of the local hot region.

Abstract: A bed of solid particles on an air distributor of a fluidized-bed furnace is fluidized by upward currents of air fed through the distributor. A fuel to be burnt in the fluidized bed is premixed with carrying air, and the fuel-air mixture is fed into the bed from a burner extending upwardly through the distributor. For utmost combustion efficiency the ratio by mass of the feed rate of the fuel-carrying air to the sum of the feed rates of the fuel-carrying air and the bed-fluidizing air is adjusted by flow control valves so as to be in the range of from about 0.2 to 0.6. The head of the burner is of such construction that the fuel-air mixture is ejected therefrom in the form of swirling jets. The burner head is usually located about 50 millimeters above the distributor.