| 摘要 |
<p>1537194 Cement from steel slag NIPPON KOKAN KK 24 May 1977 [23 June 1976] 21759/77 Heading C1H A cement manufactured from steel slag discharged from a steel-making furnace such as a converter, an open-hearth furnace or an electric arc furnace, consists of, in weight per cent:- the balance being incidental impurities. The CaO/SiO 2 weight ratio is from 2.61 to 3.27 and the CaO and SiO 2 are present principally in the form of 3 CaO.SiO 2 . The steel slag cement is substantially free of 3 CaO.Al 2 O 3 , and of free lime and alkaline constituents. The cement may be manufactured by (a) preparing a reduced steel slag by reducing a steel slag, discharged from a steel making furnace, in a reduction furnace while adding carbonaceous reducing agent, constituents detrimental to cement, viz. phosphorus and manganese, contained in the steel slag being substantially removed through the reduction treatment and the chemical composition of the reduced steel slag being adjusted principally during the reduction treatment; (b) preparing an oxidized steel slag by oxidizing the reduced steel slag in an oxidation furnace while adding SiO 2 as a chemical composition adjusting agent as required; (c) finely pulverizing the oxidized steel slag; and then (d) adding and mixing a gypsum powder in a required amount into the finely pulverized oxidized steel slag. The reduction treatment is effected until carbides, CaC 2 , are produced in an amount of from 1 to 7 weight per cent, as expressed in carbon content of the reduced steel slag. The oxidation treatment of the reduced steel slag may be effected in either the molten or solid states. Alternatively, the oxidation treatment may be initially effected in the molten state with the remainder of the treatment being carried out in the solid state. The reduction and oxidation treatments may be effected continuously, suitable apparatus for such treatments being depicted in Figs. 3 to 5 (not shown). Blast furnace watergranulated slag may be admixed with the steel slag cement in the making of mortars.</p> |
