The Problem of Phosphorus in the Production of Manganese Ferroalloys

Abstract

Ferrous metallurgy is the main consumer of manganese. The mineral resource base of manganese ores in Russia is quite extensive: the reserve of manganese ores amounts to 283.7 million tons (~2% of the world’s), and the expected reserves amounting to more than 1 billion tons. The quality of manganese ores in Russia is lower than that of manganese ores in most major producing countries. The average manganese content in Russian ores ranges from 9 to 23%. The Russian domestic manganese ores contain an increased amount of hazardous impurities, which are primarily phosphorus (from 0.2 to 0.8%). To involve domestic manganese ores into production, it is necessary to develop perfect methods for dephosphorizing manganese concentrates. Studies regarding a novel method for the dephosphorization of manganese-containing products are underway. In order to eliminate the manganese loss together with associated metal, as occurring in the case of the currently used dephosphorization method, this method consists in phosphorus reduction from the oxide melt by using gaseous carbon monoxide CO blown through the oxide manganese-containing melt, rather than using solid carbon. A novel process has been developed for smelting high-carbon ferromanganese and ferrosilicomanganese based on manganese concentrates with an increased phosphorus content. The process is carried out in a two-zone furnace equipped with a third zone intended for dephosphorization. Exhaust gases from the reduction zone containing 80–85% of carbon monoxide serve as the source of carbon monoxide required for performing dephosphorization. Methods have also been developed intended for smelting medium-carbon and low-carbon ferromanganese, as well as metallic manganese. These methods are based on a similar way for the phosphorus reduction from the oxide melt.