Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Civil and Environmental Engineering

Supervisor

Dr. Shang, Julie Q

Abstract

A sample preparation method for total sulphur measurement in reactive mine tailings was developed by ultrasound assisted digestion (USAD) and inductively coupled plasma-optical emission spectroscopy (ICP-OES) technique. KZK-1, asericite schist, was selected as the certified reference material (CRM) and Musselwhite gold mine tailings were used as tailings sample. Experimental factors (i.e. digestion time, temperature and acid-oxidant combination) were studied in two steps. In the first step, a two-level and three-factor (23) full factorial design of experiment was applied and the total sulphur was measured by USAD and ICP-OES technique. The best result at 95% confidence level (P< 0.05) was identified to be 20 minutes of digestion, 80OC and 1ml HNO3:1ml HCl, which can achieve 100% recovery of total sulphur for the selected CRM. Subsequently, the USAD method was compared with other total sulphur measurement techniques (i.e. hot plate assisted digestion method, X-ray fluorescence and LECO-CNS). The investigated method was verified by X-ray diffraction analysis. In the second step, for further improvement, the role of H2O2 (oxidant) was investigated for USAD and ICP-OES technique. The process was optimized by design of experiment and response surface methodology. The optimum result at 95% confidence level (P< 0.05) was identified as 10 minutes of digestion, 77 OC in combination with 1ml HNO3: 1ml HCl : 1.35ml H2O2 for 100% recovery of total sulphur for the selected CRM. The optimum digestion level was applied to tailings and satisfactory result was observed. A regression model equation was developed and verified by the F (Fisher’s) values as well as P (probability) values. The percentage relative standard deviation (%RSD) revealed the precision of the developed technique.


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