Alumina and Bauxite: Bauxite, Impurities and Alternative Processes
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: James Vaughan, University Of Queensland
Monday 2:30 PM
February 24, 2020
Room: 2
Location: San Diego Convention Ctr
Session Chair: Linus Perander, Yara International
2:30 PM Introductory Comments
2:40 PM Keynote
The Alumina Technology Roadmap 4.0.: Anne Duncan1; 1HATCH
The Alumina Technology Roadmap (ATR) approaches its 20th year. With a common agenda, numerous collaborative partnerships were established between producers and research establishments. A challenge to any Roadmap is to ensure the strategy remains relevant and the goals are realistic. Since the first Roadmap, our industry has grown by 2.5 times with 90 % of the growth in China. With these new players, we all are united with the recent and worsening climate change outlook. Also recent tailings failures which were not perceived 20 years ago remain a risk. With progress, we have entered the Industrial 4.0 Revolution which creates new efficiency opportunities. Behavioral safety continues to strengthen our safety culture. This paper summarizes the most recent 2018 ATR update and confirms we are working in the right areas. Engaging with all our global producers and creating compelling entrepreneurial business cases for the critical few initiatives are proposed next steps.
3:10 PM
Impacts of Mineralogy on Soluble Phosphorus Concentrations During Low Temperature Processing of Jamaican Bauxites: Michael Coley1; Anthony Greenaway1; Khadeen Henry-Herah1; 1University of the West Indies
Jamaica’s bauxite reserves are primarily from pocket deposits with highly variable mineral characteristics. Traditionally, local refineries process low phosphate hematite-rich bauxites however current resources tend towards higher phosphate concentrations which are primarily goethitic. Bauxites from different mining locations may have identical total phosphorus concentrations but differ widely in their caustic soluble phosphorus. This study compares bauxites with similar total phosphorus concentrations and examines the impacts of their phosphorus, alumina, iron, calcium, silica and titanium mineralogies on phosphorus extraction during low temperature digestion. Bauxite elemental concentrations were determined via XRF while mineralogy was characterized using XRD and the XDB programme. Caustic soluble phosphorus was measured using the molybdenum blue ascorbic acid spectrophotometric procedure. The phosphorus and calcium mineralogies were found to have the greatest impacts on low temperature caustic soluble phosphorus concentrations and, along with other parameters, have been used to predict caustic soluble P-concentrations for bauxites of widely differing characteristics.
3:30 PM
Effects of the Granular Properties of Bauxite Pisolites on the Solid/Liquid Separation in Liquid Fluidized Beds of Classifiers: Thomas Grillot1; Guy Simard1; Romain Chesnaux1; Damien Boudeville2; Lou Perrachon2; 1Université du Quebec à Chicoutimi; 2Rio Tinto
Bauxite pisolites found in the Cape York region in Australia are typically near spherical particles. Ore extracted from the Andoom (Weipa) deposit goes through a beneficiation plant to remove the finer fraction, that otherwise lead to handling problems. A key part of the beneficiation flowsheet is a fluidized bed classifier, where fine particles are removed with an overflow system. The objective of this project was to study and understand the solid/liquid separation phenomena taking place in the fluidized bed, especially determining the role of the granular properties in controlling the separation mechanisms. Lab-scale experiments, using a transparent tank and glass beads of controlled grain-size, in place of bauxite, allowed an accurate observation of the fluidized bed behavior. Computer modeling using multi-phase flow, was used to perform the numerical simulations of the experimental setup and establish the relative effects of the parameters that control the separation processes in the fluidized bed.
3:50 PM
Mineralogical Assessment of the Solid Phase Obtained on Leaching of Brazilian Red Mud: Amilton Botelho Junior1; Denise Espinosa1; Jorge Tenório1; 1University of Sao Paulo
The main residue generated during the Bayer Process is the red mud. In 2015, the quantity of waste stored around the world reached 4 billion ton. The composition of the red mud varies according to the bauxite used in the alumina extraction process. The main components of the residue are iron, aluminum, silicon and titanium. Despite that, the red mud is the main source of scandium, considered as a critical metal. Hydrometallurgical processing is the main route used for scandium extraction from red mud. For this reason, the goal of this work is the mineral assessment of the solid phase obtained on leaching of red mud. The Brazilian sample was leached by sulfuric acid. The solid/liquid ratio was 1/10 and the acid concentration was studied. Results showed that the mineral phases obtained was in agreement with the thermodynamic simulation calculated using FactSage software. Experiments were carried out at 25°C.
4:10 PM Break
4:30 PM
Inhibition of Kaolinite Dissolution in Bayer Liquor Through Addition of Lithium: Horace OGilvie1; James Vaughan1; Hong (Marco) Peng1; 1University of Queensland
With increasing reactive silica in bauxite, sodium hydroxide usage increases due to the precipitation of desilication products in the Bayer process. In this study, we report on how the presence of lithium ions in the Bayer liquor inhibits the dissolution of kaolinite. The inhibition was studied at temperatures ranging from 90-150°C with residence times up to 4 hours. The inhibition effect is attributed to the localised precipitation of LiAl(OH)7.2H2O on the surface of kaolinite. This phenomenon enables a low temperature digestion process to be contemplated, whereby gibbsite is selectively dissolved in the presence of kaolinite, leading to significant savings in sodium hydroxide as well as a low-alkaline bauxite residue. Economic trade-offs between lithium addition rates and sodium hydroxide savings are discussed.
4:50 PM
Ionic Effect of NaCl and KCl on the Flotation of Diaspore and Kaolinite using Sodium Oleate as Collector: Chaojun Fang1; Shichao Yu2; Hong Peng3; Xiaowei Deng1; Jun Wang2; 1Henan Polytechnic University; 2Central South University; 3The University of Queensland
The major type of bauxite in China is low-grade diasporic bauxite, which is mainly composed of diaspore and kaolinite. Desiliconization by flotation technology can meet the requirements of Bayer process, but Na+, K+ and Cl- will inevitably appear and affect the flotation of bauxite. The results of flotation show that NaCl and KCl have little effect on the flotation of diaspore, but NaCl have the effect of improving the flotation of kaolinite. It may be attributed to the ion size order Na+<K+<Cl-. Na+ has the ability to enter the gap of kaolinite layered crystal due to its smaller size, which increased the zeta potential and the electrostatic attraction force between kaolinite and oleate, and therefore improving the flotation of kaolinite. In addition, Na+ has salt effect on anionic collector, which also promoted the flotation of kaolinite. This study have reference significance to the industry flotation of diasporic bauxite.