Carbothermal Reduction of Iron Ore in Its Concentrate-Agricultural Waste Pellets

Zhulin Liu,Zeping Gao,Xuegong Bi,Wei Liu

doi:10.1155/2018/2138268

Abstract

Carbon-containing pellets were prepared with the carbonized product of agricultural wastes and iron concentrate, and an experimental study on the direct reduction was carried out. The experimental results demonstrated that carbon-containing pellets could be rapidly reduced at 1200 to 1300°C in 15 minutes, and the proper holding time at high temperature was 15 to 20 min. The degree of reduction gradually increased with temperature rising, and the appropriate temperature of reducing pellets was 1200°C. The weight loss rate and reduction degree of pellets increased with the rise of carbon proportion, and the relatively reasonable mole ratio of carbon to oxygen was 0.9. A higher content of carbon and an appropriate content of volatile matters in biomass char were beneficial to the reduction of pellets. The carbon-containing pellets could be reduced at high speeds in the air, but there was some reoxidization phenomenon.

Highlights

In recent years, the research of carbon-containing pellets has attracted great attention of metallurgists. e carboncontaining pellets are composed of iron-containing powders and carbonaceous additives blended with appropriate binders [1]. ey are carbon- and ironcontaining pellets or cold/hot briquettes made through pelletizing in a balling disc or through briquetting in a molding machine after thorough mixing
As the C/O ratio was increased from 0.8 to 0.9, the reduction was accelerated before 10 min, and it was more obviously accelerated as the C/O ratio was further increased to 1.0. e degree of reduction at 20 min was increased by 5.88% when the C/O ratio was increased from 0.8 to 0.9, but it almost did not change at all when the C/O ratio was further increased to 1.0, stating that it is reasonable to control the C/O ratio at a level of 0.9
It was experienced that too high C/O ratios will deteriorate the ballability of pelletizing mixture and the strength of product pellets, which would justify the use of 0.9 C/O ratio

Summary

Introduction

The research of carbon-containing pellets has attracted great attention of metallurgists. e carboncontaining pellets are composed of iron-containing powders and carbonaceous additives (coke breeze, petro-coke, pulverized coal, peat moss, and charcoal) blended with appropriate binders [1]. ey are carbon- and ironcontaining pellets or cold/hot briquettes made through pelletizing in a balling disc or through briquetting in a molding machine after thorough mixing. The research of carbon-containing pellets has attracted great attention of metallurgists. E carboncontaining pellets are composed of iron-containing powders and carbonaceous additives (coke breeze, petro-coke, pulverized coal, peat moss, and charcoal) blended with appropriate binders [1]. Yokoyama et al [4] prepared ore/coal briquettes with cement as the binder (blending ratio was 10-11 mass%) and conducted a 80 day 54 kg/t charge test at Oita BF No 2. It was attempted to partially substitute biomass char from Japanese cedar for pulverized coal in the preparation of carbon-containing iron ore hot briquettes [5]. E raw material source of biomass char is wide; in China, the forest resource is poor, but the agricultural waste output is great. Charcoal bars made with agricultural crops as raw materials gradually form market for home heating in winter

Methods

Results

Conclusion