A method of roasting metal-sulfidic material, comprising feeding solid particulate metal-sulfidic material through a feed port into a roaster having a distribution plate that supports solid particulate material fed into the roaster and accumulating as a bed on the distribution plate, wherein the material is fed into a feed zone above the distribution plate that comprises less than the entirety of the upper surface of the distribution plate, wherein the feed zone is the area on the top surface of the bed on which material that is fed through the feed port lands, wherein the roaster includes space below the distribution plate, and wherein passages are present through the distribution plate which have inlets that are open to the space and have outlets in the upper surface of the distribution plate that are in the feed zone, and wherein passages are present through the distribution plate which have inlets that are open to the space and have outlets in the upper surface of the distribution plate that are not in the feed zone; feeding oxygen-containing gas into space that is under the distribution plate; injecting oxygen enrichment gas whose oxygen concentration is higher than the oxygen concentration of the oxygen-containing gas into a region of said space that is under said feed zone and mixing said enrichment gas with oxygen-containing gas in said region to form oxygen-enriched oxidant gas in said region; and feeding said oxygen-enriched oxidant gas from said space through passages in said distribution plate under and into the metal-sulfidic material in the feed zone while feeding said oxygen-containing gas from said space through passages in said distribution plate that are not under the feed zone. feeding solid particulate metal-sulfidic material through a feed port into a roaster having a distribution plate that supports solid particulate material fed into the roaster and accumulating as a bed on the distribution plate, wherein the material is fed into a feed zone above the distribution plate that comprises less than the entirety of the upper surface of the distribution plate, wherein the feed zone is the area on the top surface of the bed on which material that is fed through the feed port lands, wherein the roaster includes space below the distribution plate, and wherein passages are present through the distribution plate which have inlets that are open to the space and have outlets in the upper surface of the distribution plate that are in the feed zone, and wherein passages are present through the distribution plate which have inlets that are open to the space and have outlets in the upper surface of the distribution plate that are not in the feed zone; feeding oxygen-containing gas into space that is under the distribution plate; injecting oxygen enrichment gas whose oxygen concentration is higher than the oxygen concentration of the oxygen-containing gas into a region of said space that is under said feed zone and mixing said enrichment gas with oxygen-containing gas in said region to form oxygen-enriched oxidant gas in said region; and feeding said oxygen-enriched oxidant gas from said space through passages in said distribution plate under and into the metal-sulfidic material in the feed zone while feeding said oxygen-containing gas from said space through passages in said distribution plate that are not under the feed zone.