What is it about?
The waste generated during the alumina production by Bayer’s process is popularly called red mud. This red mud is a rich source of iron values. Generally, the iron content in the red mud varies between 20% and 45% depending on the bauxite source. The present investigation was carried out to recover iron values from red mud. Red mud contains ultrafine particles and is highly alkaline in nature because of which it is difficult to recover the iron values from it using conventional beneficiation techniques. In the present investigation, the iron values were successfully recovered by reduction roasting followed by magnetic separation. During the process, the hematitic and goethitic iron-phase minerals present in the red mud sample are converted into magnetite and metallic irons, which are subsequently recovered using low-intensity magnetic separator. The results showed that an iron recovery of 61.85% with an iron content of 65.93% of iron concentrate could be obtained at roasting temperature of 1150°C, roasting time of 60 min, and magnetic field intensity of 0.18 Tesla.
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Why is it important?
In this work, experiments were performed to observe the effect of different parameters on recovery of iron values from Indian red mud. The effects of amount of coal used, reduction temperature, reduction time, selection of pellet size, and grinding fineness on the iron recovery and grade were investigated. The iron value recovered by the technique mentioned above can be used for the production of steel or other high-value products.
Perspectives
The recovery of iron values from red mud generated from Bayer’s process has been investigated. The conventional beneficiation methods are not efficient in recovering iron values because of the ultrafine nature of particle size and high alkalinity and mineralogy of the iron-phase minerals present. Moreover, the iron-phase minerals are present in the form of weathered hematite and goethite, which are difficult to be recovered in the conventional methods. By applying the reduction roasting method, the iron oxide present in red mud is reduced and iron-phase mineral can be economically recovered by low-intensity magnetic separation. The optimal results within the present experimental parameters for better recovery with a good grade is obtained at reduction roasting temperature of 1150° C, time of 60 min, and coal amount of 25%. The magnetic concentrate containing 65.93% iron value with a recovery of 61.85% was obtained from a feed containing 32.87% of total iron. It is possible to recover the iron values from the red mud, which could be used for iron and steel making after blending with the high-grade raw materials.
JITENDRA KUMAR SADANGI
CSIR-Institute of Minerals and Materials Technology, Bhubaneswar
Read the Original
This page is a summary of: Investigation into recovery of iron values from red mud dumps, Separation Science and Technology, April 2018, Taylor & Francis,
DOI: 10.1080/01496395.2018.1446984.
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