A Comparison Between Conventional and Microwave Heating for the Thermo-concentration of Nickel from Pyrrhotite Tails
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Authors
Jaansalu, Michael James Spencer
Date
2024-10-04
Type
thesis
Language
eng
Keyword
Nickel , Pyrrhotite , Tailings , Mineral Processing , Pyrometallurgy , Microwaves , Thermo-concentration , Thermal Upgrading , Acid Mine Drainage , Sulphides
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Abstract
In nickel sulphide ore deposits, nickel is found in one of two minerals: pentlandite, which contains approximately 30 wt% Ni, and pyrrhotite, where the nickel content is less than 1 wt% Ni. Rapid growth in the demand for nickel in the second half of the 20th Century, combined with more stringent environmental regulations, led to the removal of pyrrhotite from the smelter feeds and its disposal in tailings. Pyrrhotite remains an attractive resource as global nickel demand continues to increase. One proposed process for extracting the nickel is thermo-concentration. Thermo-concentration recovers the nickel to a ferronickel alloy with sulphur remaining in the sulphide. Significant heat input is required as the process is run at temperatures above 800°C and the reactions are endothermic. This thesis explores the use of microwave radiation to supply this heat and compares it to a conventional resistance furnace.
Thermo-concentration was performed using pyrrhotite tails from Sudbury, Ontario; two iron-bearing materials from Custer, South Dakota and Clear Hills, Alberta; and metallurgical coke. The pyrrhotite tails were used in the as-received condition and in two upgraded forms. Upgrading of the tails was performed by magnetic separation and collectorless flotation followed by magnetic separation. Microwave tests were conducted using 800 W of input power and 120 and 300 seconds of processing time. Conventional furnace tests were performed at 900°C for 35 minutes. Limited formation of ferronickel alloy particles occurred; sample metallization was less than 10% for all samples and particles that did form were too small to be easily recovered by common mineral processing techniques. Three particle populations were found of low (less than 3 wt% Ni), medium (4-23 wt% Ni) and high (greater than 18 wt% Ni) grade, all of which appeared to have formed from the solidification of a liquid matte. It is recommended that thermo-concentration trials be conducted at longer reaction times to permit further metallization.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivatives 4.0 International