Production method for hematite for iron production

Abstract

Provided is a production method for refining iron oxide (hematite), which has such a low sulfur content as to be used as a raw material for ironmaking from a leach residue containing iron oxide, the leach residue being produced by a high pressure acid leach (HPAL) process and being a raw material that can be cheaply and stably procured. In the method of producing (high purity) hematite for ironmaking by a process of adding an oxidant and sulfuric acid to nickel oxide ore and then leaching nickel, a leach residue obtained after the leaching of nickel is heated to 600° C. or more, and preferably 800° C. or more and 1400° C. or less.

Description

BACKGROUND[0001]1. Field of the Invention[0002]The present invention relates to a production method for refining a leach residue obtained by hydrometallurgical refining of nickel oxide ore into hematite that can be used as an iron-making raw material and has low-grade sulfur.[0003]2. Description of the Related Art[0004]In steel smelting, a method of charging iron ore containing iron oxide into a blast furnace along with a reductant such as coke, heating and melting the iron ore under a reducing atmosphere to obtain crude steel, and refining the crude steel in a converter to obtain desired steel has been used.[0005]The iron oxide that is a raw material of the steel is a limited resource, and furthermore it is gradually hard to obtain high-quality iron ore required to maintain a quality of steel.[0006]Meanwhile, with respect to nickel becoming a raw material of stainless steel, technology for smelting low-grade oxide ore as a raw material due to a tendency toward resource exhaustion o...

AI Technical Summary

Benefits of technology

This patent describes a method to easily obtain low-grade sulfur hematite, which can be used as an iron-making raw material. The method utilizes a cheap and stable raw material, resulting in inexpensive hematite. Additionally, the patent discusses the benefits of using waste materials, such as leach residue, in the iron-making process to reduce costs and environmental risks. The method also highlights the ease of establishing a producing process for low-grade sulfur hematite without the need for special facilities.

Problems solved by technology

The iron oxide that is a raw material of the steel is a limited resource, and furthermore it is gradually hard to obtain high-quality iron ore required to maintain a quality of steel.

However, the leach residues have no special utility value, and have been scrapped to a residue disposal yard.

For this reason, it has been a grave challenge how to secure the disposal yards for an enormous amount of leach residues generated along with the smelting.

Furthermore, the leach residue of the HPAL process cannot be directly used for the aforementioned iron-making raw material.

The reason is that the leach residue of the HPAL process contains gangue and impurities, particularly sulfur, in addition to the iron oxide and requires exhaust gas treatment, and thus is not suitable for the raw material used in the conventional iron-making process in common.

However, these neutralizers are expensive, and have a limited amount of production.

Thus, when a large quantity of neutralizer is required as in the HPAL process, it is industrially difficult to cover the whole quantity.

As such, it has been impossible to process the leach residue created in the HPAL process into the hematite and to use it as the iron-making raw material.

However, this method requires an expensive device such as an autoclave, increases a facility cost, and further has a problem even in the aspect of productivity.

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