Pre-treatment of Ultramafic Nickel Ores for Improved Mineral Carbon Sequestration

  • Author / Creator
    Bobicki, Erin R.
  • Mineral carbon sequestration (MCS) is a type of carbon storage based on natural rock weathering processes where CO2, dissolved in rainwater, reacts with alkaline minerals to form solid carbonates. Although MCS has advantages over other carbon storage techniques, an economic MCS process has not yet been developed. Two approaches were taken in this work to reduce the cost of MCS. The first approach was to use a waste material, serpentine waste from ultramafic nickel ore processing, as a feedstock. The second approach was to use pre-treatments to increase the carbon storage capacity of the waste material. Two pre-treatments were developed in this work. The first pre-treatment, microwave pre-treatment, was identified as a way not only to improve the carbon sequestration capacity of the waste, but also to improve the mineral processing of ultramafic nickel ores. Microwave pre-treatment was shown to successfully convert serpentine in ultramafic nickel ores to olivine, to improve the grindability of ultramafic nickel ores with consistent texture, to reduce the viscosity of ultramafic nickel ore slurries by an average of 80%, and to enhance the CO2 storage capacity of ultramafic nickel ores by a factor of up to 5. The second pre-treatment developed was leaching with ligands at neutral to alkaline pH. Catechol, EDTA and tiron were shown to greatly improve the leaching rate and total magnesium leached from ultramafic nickel ores. While EDTA proved to be too strong of a ligand to allow the precipitation of MgCO3 from solution, catechol and tiron promoted the formation of MgCO3, particularly at pH 10. Overall, tiron was the most effective ligand for enhancing MCS and increased the CO2 storage capacity of ultramafic nickel ores by a factor of up to 3. Although the pre-treatment techniques developed required optimization, both microwave pre-treatment and leaching with ligands at neutral to alkaline pH show promise for ultimately reducing the cost of MCS.

  • Subjects / Keywords
  • Graduation date
    Fall 2014
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.