STRATEGIES FOR PROCESSING LOW-GRADE IRON ORE MINERALS

Abstract

The conventional routes for making iron and steel require that the ore be upgraded through a series of physical separation processes in sequence. The unit operations involved include crushing, grinding, separation, dewatering, pelletization, blast furnace processing, and basic oxygen furnace processing. This complex sequence is not cost effective for many low-grade ores that are resistant to physical concentration. For example, many ores contain iron oxide in a nonmagnetic form and are so fine-grained that it is uneconomical to grind them to a fine enough size to separate the iron oxides from the gangue. Exploitation of these iron minerals needs to take a different approach, using fewer process steps than are required for conventional ironmaking. Results are presented showing that it is possible to produce metallic iron directly from low-grade ores. The metal is in a form that can be easily separated to produce a high-grade iron product, and the iron recovery is greater than can be achieved from difficult-to-process ores by conventional means.

Keywords:

• iron extraction
• iron nuggets
• iron ore
• low-grade ore
• pyrometallurgy

ACKNOWLEDGMENTS

This work was done through the Advanced Sustainable Iron and Steelmaking Center (ASISC), an NSF Industry/University Cooperative Research Center, with partial support from the National Science Foundation.

Notes

^aThe compositions for the low-grade ore and upgraded ore were calculated for an iron oxide/ coal ratio of 3.6:1.