Abstract: An apparatus for manufacturing a rapidly cooled solidified slag, which comprises: a pair of cooling drums, the peripheral surfaces of said pair of cooling drums being in contact with each other and rotating in directions opposite to each other at the same peripheral speed; a pair of weirs provided at the both ends of said pair of cooling drums so as to be in contact with the both ends of said pair of cooling drums, said pair of weirs forming a slag sump in cooperation with the upper half of the peripheral surface of each of said pair of cooling drums, and a molten slag being poured into said slag sump; a pair of gas nozzles provided adjacent the peripheral surface of each of said pair of cooling drums, said pair of gas nozzles uniformly ejecting a gas onto the molten slag, which has been deposited on the surface of said pair of cooling drums in said slag sump, to blow part of said molten slag back into said slag sump, thereby uniformly reducing the thickness of said molten slag deposited on the peripheral sur

Abstract: A method for operating a blast furnace, characterized by: adding a prescribed volume of blast furnace gas to an air for blast fed to a hot stove; oxidizing, in the hot stove, CO contained in the blast furnace gas into CO.sub.2 and H.sub.2 contained therein into H.sub.2 O to prepare a blast containing CO.sub.2 and H.sub.2 O and additionally heated by the above-mentioned oxidation; blowing the resultant blast containing CO.sub.2 and H.sub.2 O into a blast furnace through tuyeres thereof; thereby controlling the calorific value at the portions around the tuyere exits as a result of the endothermic effect produced by the reactions at the portions around the tuyere exits of the CO.sub.2 and H.sub.2 O contained in the blast with red-hot coke in the blast furnace wherein the amount of the blast is substantially equal to that of a blast without addition of a blast furnace gas.

Abstract: A runner extending from a blast furnace to a slag pit, water spray unit for manufacturing granulated slag or slag ladle is partly or wholly composed of a plurality of trough elements each made from copper or copper alloy. Each trough element comprises a hollow body having an inner space which is divided into sections by a plurality of partitions to define throughout the inner space of the body a series of passages in which a cooling medium is allowed to flow without stagnation. The cooling medium within the hollow body of the trough element is introduced under a predetermined pressure from a pipe line for supplying cooling medium into the body, whereby the cooling medium freely flows at a relatively high velocity in the passages defined by the partitions and molten slag glowing in contact with the surface of the trough element is cooled to a desired temperature which prevents wear and loss of the element and makes it possible to produce hard granulated slag from the molten slag.