The increasing need for clean metallic charge materials in quality metallurgy has given ~ise to the problem of developing lacilities tot the direct reduction of iron in certain regions of our country. Due to the economic situation in Russia, several new criteria have been established for evaluating the cost-effectiveness of building facilities for direct iron reduction. In particular, the following considerations have become paramount:-solving the given problem by rebuilding existing facilities; -minimizing capital expenditures; -achieving compatibility between the direct-reduction subdivision of the factory and its existing infrastructure (especially in regard to energy consumption).These requirements are met by a technology which is based on the metallization of an iron-ore-based raw material and involves the in-furnace conversion of natural gas. The technology includes the following (Fig. 1):-metallization of oxidized pellets in a shaft furnace by products of the conversion of natural gas;heating of the natural gas (to 400~ and circulating top gas (to 900-1000~ and mixing them with oxygen-enriched air in a tuyere before feeding them into the shaft furnace;-removal of dust from the top gas, partial recirculation of the gas, and use of the excess gas to warm the gas heaters or in the fuel system of the combine; -steam-air conversion of natural gas, 40% of the conversion being done in the heaters and 60% in the working chamber of the furnace on metallized pellets; -hot briquetting of the metallized product (if necessary). The technology also makes it possible to use a large portion of the equipment of small blast furnaces that have been removed from service: -the equipment used to receive, transport, store, and batch charge materials and charge them into the furnace;-the gas-cleaning system and water-supply system; -equipment used in compressing and heating the air blast;-oxygen plant (if present).Introduction of the proposed technology will make it possible to:

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The known reserves of manganese ores in Russia are presently estimated to be 150 million tons. The deposits located on the eastern flank of the North Ural Mountains (Polunochnoe and Marsyatskoe), in the Kemerovo Region (Usinskoe), and the Krasnoyarsk Province (Mazul'skoe) are sedimentary carbonate deposits and were formed in the Cenozoic and Paleozoic eras.Most of these deposits are composed of such minerals as calcium rhodochrosite (CaMn)CO3, oligonite (FeIMn)CO 3, psilomelane MnO2.MnO-nH20 , and pyrolusite MnO 2.Based on the chemical composition of their minerals, these ores (Table 1) can be classified as dirty low-grade manganese ores with a very low value of the ratio Mn:Fe (1:6). This precludes their use tor making ferromanganese in blast furnaces.As is known, the indicated ratio should be greater than 10 in order to make the higher grades of ferromanganese (Mn > 75%). Such a value is necessary due to the significant difference in the coefficients that characterize the transfer of Mn and Fe to pig iron (in a blast furnace, these coefficients are equal to 0.6--0.8 and 0.996, respectively). For example, the consumption of an ore with a Mn content of 50% will be as follows in the production of ferromanganese (82% Mn, 2% Si, 10% Fe, and 8% C): 82/50 x 0.8 = 2.05 tons/ton alloy. Then the maximum allowable iron content of the ore will be: 10:2.05 = 4.87.Thus, the value of the ratio Mn:Fe in the given case cannot be less than 50:4.87 = 10.3.The ratio of Mn to Fe is almost never improved by the beneficiation of ore, since iron enters the crystalline lattice of the manganese-bearing ore minerals and is transferred completely to the concentrate. The only way to increase the value of this index by an order of magnitude or more is liquid-phase reduction of the iron, such as in a Romelt furnace (invented by V. A. Romenets, A. V. Vanyukov, and E. E Vegman in 1979). The process yields synthetic high-quality fused manganese ore for blast furnaces.In the Romelt furnace (useful volume 140 m 3, hearth area 20 m 2, capacity up to 700 tons of conversion pig iron a day) built at the Novolipetsk Metallurgical Combine, about 50,000 tons of pig iron containing 0.1-0.3% Si, 0.1-0.2% Mn, 0.03-0.05% S, 0.1% P, and 4.4% C have been obtained thus l:ar in trial heats [1, 2]. Since there is no coke column in this furnace, the manganese and silicon undergo almost no reduction during the refining operation and the oxides of these metals remain in the slag; the coefficient characterizing the transfer of iron to the pig iron is 0.98. Thus, a real possibility has arisen for the almost complete separation of manganese from iron and the production of a fused manganese slag with a very low iron content and an extremely high Mn:Fe ratio (200 or more).Two trial heats were conducted in the furnace in 1988 to obtain ferromanganese with the use of sinter produced from high-quality Nikopol' manganese ore (Mn:Fe = 10.85). In both cases, the pig iron contained only 0.25-2.85% Mn. Changing the basicity of the slag within a broad range of values (CaO:SiO 2 ...