Red Mud Processing Research Articles

Calcification–carbonation method for red mud processing

Red mud, the Bayer process residue, is generated from alumina industry and causes environmental problem. In this paper, a novel calcification–carbonation method that utilized a large amount of the Bayer process residue is proposed. Using this method, the red mud was calcified with lime to transform the silicon phase into hydrogarnet, and the alkali in red mud was recovered. Then, the resulting hydrogarnet was decomposed by CO2 carbonation, affording calcium silicate, calcium carbonate, and aluminum hydroxide. Alumina was recovered using an alkaline solution at a low temperature. The effects of the new process were analyzed by thermodynamics analysis and experiments. The extraction efficiency of the alumina and soda obtained from the red mud reached 49.4% and 96.8%, respectively. The new red mud with <0.3% alkali can be used in cement production. Using a combination of this method and cement production, the Bayer process red mud can be completely utilized.

New technology of extracting the amount of rare earth metals from the red mud

The paper outlined the environmental and economic problems associated with red mud - the waste generated in processing of bauxite ore for aluminum production. The chemical analysis of red mud has identified a number of useful elements including rare earth metals. The electromembrane technology of red mud processing with extraction of valuable elements is described. A possible scheme of separation of these metals through electrolysis is also given.

A Problem of Efficient Red Mud Processing, Search for Solutions

The authors analyzed pilot projects on bauxite tail processing—red muds. The authors made a conclusion on absence of the technology for efficient muds processing in the volume comparable to their annual output. Comprehensive investigation of physical and chemical properties of the muds produced by Urals Aluminium Smelter were carried out. The authors provided the results of laboratory investigation of the red muds usage as an intensifier for sintering of iron-ore agglomerates and as a binder for production of the iron-ore pellets. The factors impeding mass use of the red muds in classic processes of ferrous metal industry were identified. It was showed that mass processing of the muds is possible in new processes of iron production out of the blast-furnaces. The authors proposed the breakthrough approach to the problem of complete processing of existing red muds, namely, their use as a binder and a collecting agent for the metals in multi-fuel gas producers of the air-lift type.

Gallium and vanadium extraction from red mud of Turkish alumina refinery plant: Hydrogarnet process

In this paper the treatment of red mud by autoclave leaching for its conversion into ferrous hydrogarnet product and extraction of valuable components (i.e. Na2O, Al2O3, Ga and V2O5) was investigated. Leaching of red mud using high modulus alkaline solution (Na2O 240g/L; αк=30) in the presence of lime at 240–260°C was found to allow the recovery of the contained values (98.5% Na2O, 65.3% AI2O3, 55.5% Ga and 65.8% V2O5) and the fixing silica in the form of hydrogarnet mud (3СаО·Fe2O3·2SiO2·2Н2О) with a low alkali content (0.35% Na2O). An effective treatment scheme for the leach solution based on precipitation and two-stage carbonization processes was developed and demonstrated. This allowed the generation of alkaline solutions suitable for recycling back to leaching stage and recovery of a concentrate (30% AI2O3) that is rich in Ga (0.32%) and V2O5 (3.7%). The chemical and phase composition of the solid products obtained from each stage of processing were determined by XRF and XRD analyses. This study has demonstrated that Bayer–hydrogarnet process can be suitably exploited for processing of red mud.

Recycling of red muds with the extraction of metals and special additions to cement

The liquid-phase reduction of iron oxides from red mud is experimentally studied. It is shown that, in addition to a metal, a slag suitable for utilization in the construction industry can be produced as a result of pyrometallurgical processing of red mud. Portland cement is shown to be produced from this slag with mineral additions and a high-aluminate expansion addition to cement.

Monitoring the processing of red mud

An approach is developed for quantitative chemical analysis of red mud and its processing products (hot metal and slag). Numerous macrocomponents and impurities may be determined simultaneously, over a wide content range (n × 10−n × 10−4%), by inductively coupled plasma atomic-emission spectrometry (ICP-AES), IR-absorption analysis, and gravimetric analysis.

Reduction of iron oxides during the pyrometallurgical processing of red mud

The results of experiments on the use of red mud in traditional pyrometallurgical processes and plants are presented. The red muds of the Ural Aluminum Plant (UAZ, Kamensk-Ural’skii) and the Alyum Plant (Tul’chiya) are shown to have similar phase and chemical compositions. The morphology of the iron oxides in red mud samples taken from mud storage is studied by Mossbauer spectroscopy. It is found that the metallic (cast iron) and slag phases that form during the pyrometallurgical processing of red mud by melting with a carbon reducer in the temperature range 1200–1500°C are clearly separated. Cast iron can be used in steelmaking, and the slag can be used for hydrometallurgical processing and extraction of nonferrous metals and for the building industry after correcting its composition.

Study on Red Mud as Secondary Resource for Iron Concentration

Depending on the analysis of the phase composition of red mud, particle distribution, distribution of reusable iron was studied clearly which size must above 360 mesh and verified by experiments. The revealed regular pattern of reusable red mud reduces the cost of the red mud processing costs. Then the rest of the distribution of iron in red mud were studied by flotation which is not the effective methold.Study provides a economic way to use red mud reused as secondary resources.