Patent ID: 8834596
Filing Date: 2014-09-16
Classification: C22B

Abstract:
1. A method for pretreating a sintering material comprising at least two types of iron ore containing coarse grains and fine powder, wherein the at least two types of iron ore each has a water of crystallization content of 3 mass % or more, said method comprising the steps of: producing S-type granules using said coarse grains as core grains and an amount of said fine powder in a first granulator, wherein said amount of said fine powder is adjusted so that the S-type granules have an average stuck thickness of fine powder to the core grains of 50 to 300 μm, and producing P-type granules using the remaining fine powder not supplied to said first granulator using a second granulator by a method comprising pulverizing the fine powder forming the material for the second granulator, adjusting the grains so that grains under 500 μm become 90 mass % or more and grains under 22 μm become more than 80 mass %, and granulating the grains in the presence of moisture in the second granulator.