Red mud
As a result, significant effort is being invested in finding better methods for safe storage and dealing with it such as waste valorization in order to create useful materials for cement and concrete.
[3][4][5] In addition to iron, the other dominant components include silica, unleached residual aluminium compounds, and titanium oxide.
[8] In October 2010, approximately one million cubic metres (35 million cubic feet) of red mud slurry from an alumina plant near Kolontár in Hungary was accidentally released into the surrounding countryside in the Ajka alumina plant accident, killing ten people and contaminating a large area.
The practice in early years was to pump the slurry, at a concentration of about 20% solids, into lagoons or ponds sometimes created in former bauxite mines or depleted quarries.
Another option for ensuring safe storage is to use amphirols to dewater the material once deposited and then 'conditioned' using farming equipment such as harrows to accelerate carbonation and thereby reduce the alkalinity.
In 2013 Vedanta Aluminium, Ltd. commissioned a red mud powder-producing unit at its Lanjigarh refinery in Odisha, India, describing it as the first of its kind in the alumina industry, tackling major environmental hazards.
[32] The key focus will be the recovery of iron, aluminium, titanium and rare-earth elements (including scandium) while valorising the residue into building materials.
Additionally, EU funding of approximately €11.5 million has been allocated to a four-year programme starting in May 2018 looking at uses of bauxite residue with other wastes, RemovAL.
As part of the H2020 project RemovAl, it is planned to erect a house in the Aspra Spitia area of Greece that will be made entirely out of materials from bauxite residue.
[33][34] In November 2020, The ReActiv: Industrial Residue Activation for Sustainable Cement Production research project was launched, this is being funded by the EU.
One of the world's largest cement companies, Holcim, in cooperation with 20 partners across 12 European countries, launched the ambitious 4-year ReActiv project (reactivproject.eu).
The latter will modify the properties of the industrial residue, transforming it into a reactive material (with pozzolanic or hydraulic activity) suitable for new, low CO2 footprint, cement products.
Fluorchemie GmbH have developed a new flame-retardant additive from bauxite residue, the product is termed MKRS (modified re-carbonised red mud) with the trademark ALFERROCK(R) and has potential applicability in a wide range of polymers (PCT WO2014/000014).
In a suitable compact solid form, with a density of approximately 3.93 grams per cubic centimetre (0.142 lb/cu in), ALFERROCK produced by the calcination of bauxite residues, has been found to be very effective as a thermal energy storage medium (WO2017/157664).
This method aims to boost alumina production efficiency while decreasing the environmental impacts typically linked with this process, notably the generation of red mud and carbon dioxide emissions.
It presents a significant decrease in caustic soda consumption and a notable reduction in red mud output, thereby minimizing hazardous waste and environmental risks.
In addition to reducing red mud production, the IB2 process aids in lowering CO2 emissions, primarily through the optimized treatment of low-grade bauxite.
