Partially-reduced iron producing apparatus and partially-reduced iron producing method

A partially-reduced iron producing method comprising the steps of:

• laying a portion of raw material pellets as ignition raw-material pellets to a predetermined height on an endless grate, the raw-material pellets made of a material formed by mixing and pelletizing a reduction carbon material and a raw material containing iron oxides;
• heating the ignition raw-material pellets laid on the endless grate to a reduction temperature range by heating means, and then packing an added portion of the raw-material pellets on the ignition raw-material pellets;
• heating the added raw-material pellets adjacent to the ignition raw-material pellets by use of a heat of the ignition raw-material pellets to generate and combust a flammable volatile component from the reduction carbon material in the raw-material pellets;
• causing a temperature of the added raw-material pellets to further rise by use of a combustion heat of the flammable volatile component, so that a reduction reaction proceeds and a carbon monoxide gas is generated, while causing the added raw-material pellets to be heated by the combustion heat, so that a flammable volatile component is generated from the reduction carbon material in the added raw-material pellets;
• increasing a concentration of the carbon monoxide gas that is near the added raw-material pellets having the temperature further raised, to a combustion range of the carbon monoxide gas by supplying an oxygen-containing gas to the raw-material pellets, so that the carbon monoxide gas combusts and a combustion zone is formed, the oxygen-containing gas made by circulating a remaining portion of the flammable volatile component and the carbon monoxide gas and mixing the remaining portion and the carbon monoxide gas with air;
• and
• moving the combustion zone sequentially in a bed height direction of a packed bed of the raw-material pellets in a period between the packing of the raw-material pellets onto the ignition raw-material pellets and discharging thereof, so that the packed bed of the raw-material pellets is thermally reduced and a partially reduced iron is produced.