Mn and Cr Extraction from the Secondary Wastes of Metallurgical Combines by Gas-Phase Conversion in Nitriding Media

An approach based on the gas-phase processing of secondary wastes in an HNO₃ (vapor)–air or NO_x–H₂O (vapor)–air atmosphere with further Mn and Cr leaching with water is proposed for Mn and Cr extraction from the secondary wastes of metallurgical plants (fly ash from the ore-dressing plant of the Norilsk Combine and rock refuses from the Punda Gourda Nickel Production Combine of the Cuban State-Owned Commercial Caribbean Nickel Company). It is shown that the preliminary treatment of secondary wastes in a nitriding atmosphere at a temperature of 400–425 K for 5 h makes it possible to leach Mn from the volume of secondary wastes. For the fly ash from the ore-dressing plant of the Norilsk Combine and the rock refuses from the Punda Gourda Nickel Production Combine of the Cuban State-Owned Commercial Caribbean Nickel Company, the degree of Mn extraction with water is less than ~33 and ~65% of their total content in the wastes, respectively. The degree of Cr extraction is less ~2% in all cases.