拜耳法赤泥碳热还原生产灰铸铁

Production of Gray Cast Iron by Carbothermal Reduction of Bayer Red Mud

摘要: 本文提出了从赤泥和红土镍矿中提取灰铸铁的工艺。将赤泥、红土镍矿和焦粉按确定的比例混合均匀，利用造球机制备成一定尺寸的球团，烘干后在电弧炉中经碳热还原获得铸铁。观测所得铸铁石墨形态的变化，测定焦炭含量对铁镍等金属还原率的影响以及铸铁的洛氏硬度。实验表明，焦炭含量的增加有利于提高铁镍等金属的还原率。不加红土镍矿时，铁合金金相组织为白口铸铁，碳主要以渗碳体形式存在，当镍含量达到0.6%或更多时，出现游离的石墨薄片，微观结构呈现灰铁特征。随着镍含量的增加，游离石墨增加，渗碳体减少，显微组织由白口铸铁变为灰口铸铁。综上所述，该工艺是一种具有应用前景的从赤泥中还原铸铁的技术，对消除拜耳法赤泥的污染危害具有重要意义。

Abstract: This paper presents a process for extracting gray cast iron from red mud and laterite nickel ore. Red mud, laterite nickel ore and coke powder were mixed evenly according to the determined proportion, and pellets with a certain size were prepared by pelletizing mechanism. After drying, cast iron was obtained by carbothermal reduction in electric arc furnace. The graphite morphology of cast iron was observed, the effect of coke content on the reduction rate of iron, nickel and other metals and the Rockwell hardness of cast iron were measured. The results show that the increase of coke content is conducive to improve the reduction rate of iron, nickel and other metals. Without laterite nickel ore, the metallographic structure of ferroalloy is white cast iron, and carbon mainly exists in the form of cementite. When the nickel content reaches 0.6% or more, free graphite flakes appear, and the microstructure presents the characteristics of gray iron. With the increase of nickel content, free graphite increases, cementite decreases, and the microstructure changes from white cast iron to gray cast iron. In conclusion, this process is a promising technology for reducing cast iron from red mud, which is of great significance to eliminate the pollution harm of Bayer process red mud.