Reduced iron production method
Disclosed herein is a reduced iron production method enabling heat to be input well into reduced-iron raw materials on a hearth covering material in a reduction-melting furnace to improve the efficiency of treatment thereof. The reduced-iron raw materials are set on the hearth covering material through their falls and reduced on the hearth covering material. The hearth covering material is constituted by carbon materials each having a particle diameter of 5 mm or less. At least 7 mass % of the carbon materials have respective particle diameters each being 0.1 mm or less. This restrains the reduced-iron raw materials from embedment into the hearth covering material.
1. A method for producing reduced iron, the method comprising:
successively charging a plurality of reduced-iron raw materials each containing a carbonaceous reducing agent and an iron oxide into a reduction-melting furnace having a hearth that travels in a horizontal direction and a hearth covering material formed of powder laid on the hearth and letting the reduced-iron raw materials fall onto the hearth covering material to set the reduced-iron raw materials on the hearth covering material; and
successively reducing each of the reduced-iron raw materials on the hearth covering material along with travel of the hearth to thereby produce reduced iron and discharging the reduced iron produced to outside of the reduction-melting furnace,
wherein the hearth covering material is constituted by carbon materials each having a particle diameter of 5 mm or less,
wherein at least 7 mass % of the carbon materials have respective particle diameters each being 0.1 mm or less,
wherein the reduced-iron raw materials are spherical,
wherein the successively charging comprises ejecting the reduced-iron raw materials downward from a lower surface of a ceiling located above the hearth and letting the reduced-iron raw materials fall onto the hearth covering material while giving a horizontal velocity, which is in the same direction as a travel direction of the hearth and greater than a moving speed of the hearth, to the reduced-iron raw materials to thereby roll the reduced-iron raw materials on the hearth covering material in a direction of the horizontal velocity,
wherein the successively charging comprises letting the reduced-iron raw material fall on the heath along a slope surface formed internally of the ceiling, and
wherein the slope surface has an inclination angle of from 36° to 60° with respect to ceiling.
2. The method of claim 1 , further comprising, prior to the successively charging:
preparing the hearth covering material by adding fine-particle carbon materials each having particle diameters of 0.1 mm or less to carbon materials each having a particle diameter of 5 mm or less.
3. The method of claim 1 , wherein
the carbon materials are anthracite or coke.
4. The method of claim 1 , wherein the reduced-iron raw materials fall onto the hearth covering material at a horizontal velocity corresponding to an inclination angle of a slope surface formed internally of the ceiling in addition to a downward velocity due to gravity.
5. The method of claim 1 , wherein the slope surface is a curved surface as viewed from sides of the reduction-melting furnace.