Method for recovering iron and phosphorus from steelmaking slag

Abstract

Provided is a method for reclaiming iron and phosphorus from steelmaking slag, which comprises a first process, in which steelmaking slag that contains phosphorous, such as dephosphorization slag, is reduction treated using a reducing agent, such as carbon, Si, or Al, to reduce and recover iron oxides and phosphorus oxides in the slag as phosphorus-containing molten steel, a second process, in which the steelmaking slag, from which the iron oxides and phosphorus oxides have been removed, is used as a CaO source in a sintering process, and the resulting sintered ore is recycled to a blast furnace, a third process, in which the phosphorus-containing molten steel recovered by the aforementioned reduction treatment is dephosphorization treated until the phosphorus concentration in the phosphorus-containing molten steel reaches 0.1% by mass or less, and the phosphorus is concentrated into a CaO-based flux, and a fourth process, in which the phosphorus-containing molten steel with a phosphorus concentration of 0.1% by mass or less is mixed as an iron source in the blast furnace hot metal, whereby phosphorus and iron can be inexpensively recovered from said steelmaking slag, and the reclaimed phosphorus and iron can each be effectively used as resources.

Description

technical field [0001] The present invention relates to a method for recovering iron and phosphorus contained in steelmaking slag containing phosphorus, such as dephosphorization slag produced by pre-dephosphorization treatment of molten iron (hot metal). Background technique [0002] Phosphorus (P) is contained in molten iron melted in a blast furnace due to the composition of iron ore. Phosphorus is a harmful component to steel, and conventionally, dephosphorization has been performed in the steelmaking process in order to improve the material properties of steel products. In this dephosphorization treatment, phosphorus in molten iron or molten steel is usually oxidized with oxygen or iron oxide, and then the oxidized phosphorus is fixed in slag mainly composed of CaO, thereby removing phosphorus. When oxygen is used to oxidize phosphorus in molten iron or molten steel, iron is also oxidized, and therefore iron contained in slag is in the form of iron oxide even when iron...

AI Technical Summary

Problems solved by technology

Obviously, when recycled to an oxidation process such as pre-dephosphorization treatment, the function as a dephosphorization agent is also impaired, and the amount of recycling is limited.

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