Page 16 - Annual Report_21-22

MINERAL PROCESSING

Development of a process for reduction roasting of low and lean grade iron ores using fluidized
bed roaster (in pilot scale) to maximize the recovery of iron values

Utilization of low/ lean grade iron ore for iron and
steelmaking is the need of the hour to meet the future
demand of iron and steel. Upgradation of these low/ lean
grade iron ore can be achieved by adopting reduction
roasting followed by magnetic separation. The main
objective of this project is to develop a suitable process
for reduction-roasting of low and lean grade iron ore
fines/ slimes in a pilot-scale fluidized bed roaster. To
carry out the reduction roasting of low/ lean grade iron
ore fines, the existing batch type fluidized bed reactor
with 1.5m height was modified to a 4m high continuous
type FBR with PID controlled electrically heating system.
The present capacity of this modified FBR is 100 kg/hr.
The modified FBR is shown in the Figure. The present
study aims at utilizing the high ash non-coking coal as a
reductant for the reduction reaction. The results obtained
from this study are promising. Fig. Modified Continuous Fluidized Bed Reactor

Pilot scale study of reduction of phosphorous content in high phosphorous Indian iron ores

The occurrence and association of phosphorous in iron content of 0.13% through the application series of physical
ore is complex with the various mineralogical association. beneficiation. High-temperature reduction roasting
As the phosphorous content in steel crosses above a and hydro-metallurgical route indicated a reduction of
certain permissible limit, it adversely affects the steel appreciable phosphorous content below 0.05%. The
quality. Therefore, its content in iron ore feed needs to current investigation deals with upscaling the experiments
be controlled beforehand through applied metallurgical on a pilot scale. After a successful pilot-scale study,
processes. Laboratory scale investigation has been done industrial participation and trial will help in utilizing these
on selected Indian iron ore samples with the phosphorous high phosphorous bearing iron ore.

An innovative and viable process for recovery of iron values from red mud and processing of
non-iron material for developing value-added products – complete utilization of red mud

Red mud is produced in the process of alumina extraction upon the mineralogical composition of the bauxite and
from bauxite. In this context, the development of its extraction efficiencies. The treatment and utilisation of
effective handling, storage, usage and management stands high volume red mud waste has been a major challenge
as a burning issue for the global community. The Bayer for the alumina industry. A typical chemical analysis
process is the principal industrial means of refining bauxite would reveal that red mud contains silica, aluminum, iron,
to produce alumina (aluminium oxide). The majority of calcium, titanium, as well as an array of minor constituents,
global alumina production is through Bayer’s process. namely: Na, K, Cr, V, Ni, Ba, Cu, Mn, Pb, Zn etc. Therefore,
Red mud is highly alkaline, which is a potential pollution an in-depth R&D study is needed to utilise and recover the
threat to water and land close proximity of the alumina different mineral values from red mud. The main objective
refinery plant. Meanwhile, high costs are associated with is to minimise waste generation by recovering the mineral
the large area of land needed for storage of the residue values. The iron phase minerals are almost 40-60% in the
and also the polythene lining on the surface in the storage red mud. If 70-80% of iron values can be recovered, a
pond provided to avoid ground water contamination. The good amount of waste generation can be minimised. The
disposal of red mud is a major problem in alumina plants major challenge is to aim for bulk utilization of red mud in
throughout the world. Usually, the production of 1 tonne a reliable manner.
of alumina generates 1-1.5 tonnes of red mud depending

14 ANNUAL REPORT 2021-22