| Various aspects of processing high-manganese slags, generated during the production of standard grade ferro-manganese, have been studied in laboratory scale plasma furnaces. These laboratory furnaces are based on the use of conventional graphite electrodes rather than water cooled non-consumable torch devices. The reactor system has separate, distinct zones for pre-heating, melting and smelting. This unique feature assists in the removal of undesirable elements from the molten alloy.; Ferro-manganese alloys containing 70% to 90% manganese, with phosphorus and sulphur contents less than 0.01%, and silicon contents less than 0.3% or as high as 8%, depending on the alloy requirements, have been produced, with manganese recoveries from the slag in excess of 75%.; It has been found that 3 wt % of MgO is required to stop the dissolution of the magnesia refractory. Thus with proper control of slag chemistry, it has been demonstrated that refractory dissolution within the hearth zone of the plasma reactor can be inhibited. In addition, by periodically working with an acidic slag, excessive skull formation can be prevented.; The reduction of manganese oxide in the Extended Arc Flash Reactor, EAFR, takes place in two distinct stages, an initial fast stage characterized by rapid gas evolution followed by a second slower stage in which gas evolution virtually ceases.; In contrast to conventional steelmaking experience, dephosphorization in the EAFR shows very little dependence on slag basicity and occurs at lower oxygen potentials with the reactions showing an opposite temperature dependence. Thus it is clear that phosphorus removal is not by the normal slag-metal reaction and mass balances show that phosphorus is lost mainly in the gaseous phase. In a similar way to dephosphorization, volatilization also plays a major role in the successful desulphurization in the EAFR.; It has been established that the EAFR can be used for the production of standard ferro-manganese from manganese ores.; Contaminated ferro-manganese fines have also been successfully processed in the EAFR to produce high quality ferro-manganese alloys containing over 82% manganese. |
