International Journal of Minerals, Metallurgy and Materials
Volume 25, Number 6, June 2018, Page 591
Corresponding author: Ti-chang Sun E-mail: email@example.com
© University of Science and Technology Beijing and Springer-Verlag GmbH Germany, part of Springer Nature 2018
Feasibility of co-reduction roasting of a saprolitic laterite ore
and waste red mud
Xiao-ping Wang, Ti-chang Sun, Jue Kou, Zhao-chun Li, and Yu Tian
School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China
(Received: 11 October 2017; revised: 27 November 2017; accepted: 10 December 2017)
Abstract: Large scale utilization is still an urgent problem for waste red mud with a high content of alkaline metal component in the future.
Laterite ores especially the saprolitic laterite ore are one refractory nickel resource, the nickel and iron of which can be effectively recovered
by direct reduction and magnetic separation. Alkaline metal salts were usually added to enhance reduction of laterite ores. The feasibility of
co-reduction roasting of a saprolitic laterite ore and red mud was investigated. Results show that the red mud addition promoted the reduction
of the saprolitic laterite ore and the iron ores in the red mud were co-reduced and recovered. By adding 35wt% red mud, the nickel grade and
recovery were 4.90wt% and 95.25wt%, and the corresponding iron grade and total recovery were 71.00wt% and 93.77wt%, respectively.
The X-ray diffraction (XRD), scanning electron microscopy, and energy dispersive spectroscopy (SEM-EDS) analysis results revealed that
red mud addition was helpful to increase the liquid phase and ferronickel grain growth. The chemical compositions “CaO and Na
O” in the
red mud replaced FeO to react with SiO
to form augite.
Keywords: laterite ore; red mud; reduction roasting; phase transformation
Nickel laterite deposits are divided into two primary parts:
limonite and saprolite . The reduction of saprolitic laterite
ores is much more difficult than that of limonitic laterite .
Since serpentine undergoes dehydroxylation during roasting,
the resulting phases, such as olivine and pyroxene, are not
conducive to reduction . So, the key issues in the reduc-
tion roastingmagnetic separation of saprolitic laterite ores
are: (1) the liberation of nickel and iron from their host min-
erals, (2) adequate reduction of iron and nickel oxides, and
(3) the growth of ferronickel particles. Previous research
showed that the addition of alkali compounds, such as so-
dium and calcium salts, was usually used for the efficient
recovery of nickel from laterite ores. Some researchers 
studied the effect of calcium salts on the reduction of a sa-
prolitic laterite ore. And several studies completed a simula-
tion study on the mechanism of sodium salts on promoting
the reduction of laterite ores [3,812]. The effects of addi-
tives such as sodium and calcium salts on the reduction of
laterite ores are significant, but their prices are high. There-
fore, it is necessary to study the use of low cost alternatives
to replace them in the reduction of laterites.
Red mud is an alkaline waste byproduct generated by the
extraction of alumina from bauxite . Appropriate man-
agement of red mud is becoming a global concern following
increased awareness of the need for environmental protec-
tion. The red mud is mainly composed of a mixture of
oxides and hydroxides such as Fe
, and very small amounts of other met-
al oxides . Therefore, a comprehensive use for red mud
is also crucial for economic reasons .
Therefore, in this study, waste red mud containing large
amounts of CaO and Na
O was added to a saprolitic ore.
This mix was then subjected to reduction roasting followed
by magnetic separation. This was then tested to determine
the effect of red mud on the reduction of as-received sapro-
litic laterite and test the feasibility of co-reduction. In
additon, the effects of red mud on phase transformations and
ferronickel grain growth were investigated.