De-watering, disposal and utilization of red mud: state ... - Redmud.org

– option of at least partial utilization of the low soda bauxite residue
– option of making desilication product (Bayer-sodalite) as a new by-product for sale,
and/or converting it to value-added products such as zeolites at a competitive cost
– more cost effective pressure decantation instead of relatively large settlers
– processing of bauxite bodies with relatively high silica and/or high boehmite and/or
high goethite content do not pose a processing problem.
The ILTD Process makes possible to obtain such a bauxite residue with a chemically
combined soda content of as low as 1-1.5% Na2O, opposite to the 8-9% Na2O content of the
red mud of the conventional process. The iron content of the low soda bauxite residue of the
ILTD Process can be as high as 60-70% Fe2O3 instead of the 50% Fe2O3 of the red mud of the
CLTD Process. These figures are based on tests with a typical Trombetas bauxite, Brazil [77].
Therefore the ILTD Process has benefits both from the point view of the usage of the residue
and its environmentally sustainable disposal. The ILTD Process has been further developed
since its patenting.
9. Waste paradox
There is a paradox regarding the utilization of wastes:
– There are cheap competitive materials and the transportation costs hinder its
transportation to a large distance, therefore the price in large quantities should be
cheap enough to be competitve
– there are high value added applications, but these are marginal in quantites
compared with the amount of production of bauxite residue by-product.
10. Conclusions
Consideration of red mud disposal should be based on alumina process technology and with
weather and socio-economical circumstances.
When the method for the transportation and the disposal of the bauxite residue is selected, the
red mud washing system and the overall water balance should be considered at the same time.
Special attention should be paid for preventing dusting and the progressive rehabilitation of
the filled red mud disposal areas.
The most up-to-date solution is the dry mud stacking system, provides a technical solution
what satifies the environmental regulations in a cost-effective manner. In such a case the
disposal of the red mud is safe. The bauxite residue can be obtained with characteristics which
make possible disposal as a non-hazardous material.
Due to the research and development achievements so far and the ongoing activities, the
bauxite residue has several useful and environmentally sustainable applications.
Though there has been continuous progress, utilization of the red mud has not been solved in
great quantities. It can be reasonably expected that using the proven and emerging
technologies the amount of bauxite residue that are used in an economic and environmentally
sustainable way will considerably increase.
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