Red mud applications in building materials

Overview

Topic status: In progress

Project Description

Bauxite refinery residues (red mud) are derived from the Bayer process by the digestion of crushed bauxite in concentrated caustic (NaOH) at elevated temperatures. The process results in the dissolution of gibbsite (Al(OH)3) and boehmite (AlOOH) as sodium aluminate, while the remaining insoluble residue (45% liquor and 55% solid mud) is removed by means of flocculation and decantation. Red mud varies in physical, chemical, and mineralogical properties, however, the general consensus of the composition of red mud has been found to be largely composed of iron oxides, primarily hematite (Fe2O3), and goethite (FeOOH), boehmite, other aluminium hydroxides, calcium oxides, titanium oxides (anatase and rutile), and aluminosilicate minerals (sodalite).

RM is a form of laterite (soil types rich in iron and aluminium) and has the potential to be used for building materials. When moist, laterites can be easily cut with a spade into regular-sized blocks and upon exposure to air, gradually hardens as the moisture between the flat clay particles evaporates and the larger iron salts lock into a rigid lattice structure and become resistant to atmospheric conditions. Therefore, there is the potential for red mud to be used in the production of commercial products such as; bricks, road base, cement aggregate, pavement blocks and ceramics.

Research Activities

This project will involve the full characterisation of red mud, and red mud treated with acid, seawater and thermal activation techniques. An investigation into the specifications required for different building materials will be essential and the differently treated red muds will then be tested to see if these specifications are met for each type of building material. These tests will involve a range of physical (durability, strength, weatherability, load, slip resistance) and chemical (composition, microstructural) tests. Other physical properties such as grading, density, porosity, strength, rheology, mechanical, electrical and thermal properties will be analysed. An investigation on the microstructure aspects of red mud will be used to determine product failure or defects, failure mechanisms, inclusions, grain size and bonding structures, surface analysis, degradation and contaminants. Students working on this project will coordinate tests with Rio Tinto Alcan.

The project objectives are to:

  • characterise red mud that has undergone different chemical and physical treatments
  • determine the specifications required for commercial building materials
  • estimate the feasibility of the different red mud materials for the five different building products investigated

The project duration is for up to 8 weeks and specific times can be tailored to the individual needs of the student (generally between the hours of 9am and 5pm) within the general time period mid-November to mid-February. A top up scholarship may be available for this project and will be confirmed closer before the project commences.

Study level
Vacation research experience scholarship
Supervisors
QUT
Organisational unit

Science and Engineering Faculty

Research area

Chemistry

Contact
Please contact a supervisor for enquiries.