New indices of sinter basicity

Abstract

In May of 1942, the Chusovoi Metallurgical Plant began the construction of a new sinter plant designed to utilize iron-and vanadium-bearing wastes generated by the factory. The facility is still being successfully operated. During the period from 1994 to 1998, 1763 tons of vanadium alone were returned to the production cycle by the sinter plant. This amount is roughly 15% of the amount of vanadium present in the pellets and sinter obtained from the Kachkanar Mining-Concentration Combine (KGOK).Until 1991, the sinter plant also made use of chromium and manganese. Special local sinter with high concentrations of these elements were melted in a small blast furnace to make high-alloy cast iron. The cast iron was widely used in machine plants and the cement industry to make high-strength parts and balls for ball mills [1, 2].The local sinter was used in blast-furnace smelting and other applications. Until 1971, the charge used in the blast furnace consisted mainly of unfluxed Kusinsk sinter and untreated Pervoural'sk ore. As a result, the consumption of raw limestone reached 337 kg/ton pig iron (1961). Fluxing of the local sinter was the only way to reduce limestone consumption in the charge [3, 5, 6], and the level of fluxing of that material was kept very high. For example, from 1967 to 1971, the average level was 3.31 based on the ratio CaO/SiO 2 and 3.70 based on the ratio (CaO + MgO)/SiO 2 ( Table 1).The plant attempted to make sinter with a higher basicity. During the September-October period of 1965, it conducted trial sinterings which produced sinter with a basicity above 6.0. The high-basicity sinter had a low concentration of the lower oxide and fewer fines, but the factory stopped making iron-bearing flux due to the unavailability of high-quality sinter-grade limestone [4].Since the plant began to use fluxed pellets and sinter from the Kachkanar Mining-Concentration Combine, the need for raw limestone in the charge of the blast furnaces has been sharply reduced, and there has been a corresponding reduction in the basicity of the local sinter.It should be noted that, by itself, the basicity of the material does not give a completely accurate picture of the possibility that exists for replacing limestone. If the initial materials have a basicity greater than or equal to the basicity blast-furnace slag, then the higher the SiO 2 content of those materials (and, accordingly, the higher their CaO content) when basicity is equalized, the lower the consumption of raw limestone in the blast-furnace heat, other conditions being equal. Conversely, if the initial materials are less basic than the furnace slag, then the consumption of raw limestone will be greater in proportion to the SiO 2 content of those materials (when basicity has been equalized) (Fig. 1).The fluxing ability of the material is more accurately characterized by the following relations:where CaO, MgO, and SiO 2 are the concentrations of the respective oxides in the material, % (CaO/SiO2)sZ and ((CaO + MgO)/SiO2)sl is the basicity of the blast furnace...