Continuous nickel matte converter for production of low iron containing nickel-rich matte with improved cobalt recovery

A system for directly and continuously converting high iron nickel-cobalt and nickel-cobalt-copper mattes into low-iron mattes, a low value-metal containing discard slag and a gas of high sulfur dioxide content, the system comprising an oxygen reactor, the reactor including a substantially closed, elongated, gently sloped downward toward product discharge, cylindrical, tilting, concurrent gas-slag flow and countercurrent matte-slag flow refractory lined vessel having a roof, the reactor subdivided into an oxidizing gas top-blown, gas bottom-stirred finishing zone, a slag reducing zone, and an oxidizing zone disposed intermediately between the finishing zone and the slag reducing zone, the reactor adapted to contain a molten bath including matte and slag, a barrier extending from the roof into the molten bath thereby partially separating the finishing zone from the oxidizing zone, the barrier including a bath underflow passage between the oxidizing zone and the finishing zone and a gas passage between the finishing zone atmosphere and the oxidizing zone atmosphere, a slag discharge taphole disposed at the end of the slag reducing zone, a product discharge taphole disposed at the end of the finishing zone, a gas off-take disposed near the end of the slag reducing zone, at least one bottom-stirring gas injector disposed in the bottom of the finishing zone, at least one top-blowing oxidizing gas injector disposed in the roof of the finishing zone, at least one material feeder disposed in the roof of the oxidizing zone, at least one material feeder disposed in the roof of the reducing zone, a plurality of spaced fluid-shielded, submerged oxygen injectors generating bath-oxidizing bubble plumes disposed in the bath of the oxidizing zone, a plurality of spaced fluid-shielded, submerged carbonaceous fuel-oxygen injectors generating bath-reducing bubble plumes disposed in the bath of the reducing zone, quiescent bath settling regions interposed between each of the submerged oxygen injector bubble plumes and between each of the submerged carbonaceous fuel-oxygen injector bubble plumes, a quiescent settling region interposed between the plurality of submerged oxygen injector bubble plumes and the plurality of submerged carbonaceous fuel-oxygen injector bubble plumes, a quiescent settling region interposed between the plurality of submerged carbonaceous fuel-oxygen injector bubble plumes and the slag discharge, a quiescent settling region interposed between the plurality of submerged oxygen injector bubble plumes and the barrier, and the inputs to each of the submerged injectors independently regulated to control the oxygen potential along the length of the reactor, and the product discharge taphole connected to a subsequent treatment facility.

A continuous process for maximizing the recovery of value-metal from high-iron nickel-cobalt and nickel-cobalt-copper mattes of controlled sulfur content while converting a reactor feed into a low-iron matte product and maximizing the sulfur dioxide concentration of the resultant off-gas, the process comprising establishing a molten bath in a substantially closed, elongated, gently sloped downward toward product discharge, cylindrical, tilting, concurrent gas-slag flow and serially locally agitated, countercurrent matte-slag flow, refractory lined vessel, subdivided into an oxidizing gas top blown, gas-bottom stirred finishing zone having a bath eye therein, a reducing zone, and an intermediate oxidizing zone disposed therebetween, the finishing zone and the oxidizing zone separated by a barrier extending from the roof into the molten bath, the barrier including a bath underflow passage between the oxidizing zone and the finishing zone and a gas passage between the finishing zone atmosphere and the oxidizing zone atmosphere, introducing solid reactants selected from the group consisting of mattes, roasted mattes, fluxes, pyrite, pyrrhotite, iron and steel scrap, ferrosilicon and carbonaceous and appropriate recycled materials into the vessel, introducing reactants selected from the group consisting of oxygen, nitrogen, natural gas, petroleum oil, coal and water into the vessel by a plurality of regulated, spaced, fluid-shielded, submerged injectors disposed in the oxidizing and reducing zones, converting the solid reactants to form fluid matte and slag in the oxidizing zone, treating the slag in the reducing zone to recover its value-metal content, establishing in the oxidizing zone bath a sequential plurality of increasingly oxidizing bubble plume turbulent mixing regions each separated by a quiescent settling region as the matte flows at increasingly high oxygen potential to the finishing zone, establishing in the reducing zone bath a sequential plurality of increasingly reducing bubble plume turbulent mixing regions each separated by a quiescent settling region as the slag thus flows at increasingly low oxygen potential to a discharge taphole, flowing the matte produced in the oxidizing zone into the finishing zone for final increase in oxygen potential and decrease in its iron content and production of a floating cobalt-rich mush, and discharging the reactor products.