A Novel Process for Producing Ferromolybdenum Powder Master Alloy without Generating Secondary Pollutants through a Two-Step Hydrogen Reduction Process

Abstract

A new process for producing ferromolybdenum powder master alloy without generating secondary pollutants by a two-step hydrogen reduction process involving MoO 3 and mill scale has been developed. In this process, mill scale which is an iron byproduct generated from the steel rolling process is used as an iron source. Experimentally, ferromolybdenum powder master alloy was produced by a two-step hydrogen reduction process: The first hydrogen reduction stage was carried at a horizontal furnace for 60 min at 848 K under a hydrogen gas at a partial pressure of 101.3 kPa, and the second hydrogen reduction stage was done at the same furnace for 40 min at 1123 K under the same hydrogen partial pressure. In the process, the reduction reactions of MoO 3 to MoO 2 and mill scale to Fe proceed simultaneously in the first reduction step, and then the reduction reaction of MoO 2 to Mo does in the second reduction step. The reaction rate of the second step in the two-step hydrogen reduction process of MoO 3 -Fe 2 O 3 mixture was also measured under isothermal condition in hydrogen atmosphere using TGA equipment. As an example, at 1173 K under a hydrogen partial pressure of 101.3 kPa, almost 100% of MoO 2 was reduced to Mo in 5 min. The nucleation and growth model were found to be applicable to the reaction rate. The reaction was first order with respect to hydrogen partial pressure and had an activation energy of 83.8 kJ/mol (20.1 kcal/mol).

Investigation of the Reduction of a Molybdenum/Iron Molecular Nanocluster Single Source Precursor

“…This approach produces ferro-molybdenum particles in the typical size range of microns to millimeters. However, the aluminothermic reaction generates large amounts of slag and dust, inevitably causing environmental issues [10]. By contrast, the gas-solid reduction route offers advantages in the versatility of reduction gases (CH 4 , CO, H 2 ), relatively low processing temperatures, and production of powders with particle size in the micro and nano regime [11].…”