University of Toronto
Department of Chemical Engineering and Applied Chemistry

CURRENT PROJECTS

 

Magnesium Solubility in Mixed Electrolytes
Matthew Jones
 
It has been found that introducing sulphates into high-strength chloride solutions will induce the precipitation of Magnesium in the form of kieserite.  Recently developed hydrometallurgical processes are attempting to utilize this behaviour in order to reject magnesium from process streams in a cost effective manner.  The purpose of this project is to use OLI Software to model this behaviour.  In order to do this, ionic interaction parameters and reference state properties are determined using existing literature data and added to the OLI Mixed Solvent Electrolyte database of thermodynamic parameters.
 
Evaluating the Potential of Scaling due to Calcium Compounds in Hydrometallurgical Processes
Ghazal Azimi
 
Chemical Modelling is a useful tool in the developing, designing, and controlling of industrial processes such as hydrometallurgical processes which are of our interest. Once a model is validated against experimental data, it can be used to predict beyond the range of parameterization which is the range of industrial plant data. These models can be used for planning an experimental procedure and for selecting a process. As a result, they provide considerable economic benefits during feasibility studies.
The objective of this work is to investigate the solubility of calcium sulphate in mixed sulphate-chloride-carbonate solutions encountered in fully or partially neutralised process waters. This can be accomplished with the aid of OLI software platform (http://www.olisystems.com), which provides an advanced thermodynamic framework for predicting complex aqueous-based phase equilibrium over wide temperature and pressure ranges, i.e., -50 to 300 ºC, and 0 to 1500 bar, respectively. 
 
Chemical modeling of ammonia solutions in Ni/Co hydrometallurgy
 
Chemical modeling is becoming increasingly useful in the development, analysis, design and control of industrial chemical processes, particularly in hydrometallurgy. Chemical modeling is a very powerful tool to predict and understand the behaviour of complex aqueous systems such as ammoniacal systems containing Ni, Co, Cu, Zn sulphates, and ammonium sulphate. The vapour pressure of ammonia in aqueous ammoniacal multicomponent solutions is being studied by using the Mixed Solvent Electrolyte (MSE) thermodynamic framework implemented in the OLI software.

 

Recovery of base metals from slags by high pressure oxidative leaching

M. Baghalha (now with Sharif University of Technology, Iran), Ilya Perederiy and Yunjiao Li (now with Ortech)

 

There are large amounts of non-ferrous slags dumped from nickel and copper smelters all over the world each year. Recovery of base metal values from this kind of slags is important not only for saving metal resources, but also for protecting the environment. The conventional method for recovery of base metals from the slags is re-smelting, ehich is very costly. However, no one to date has come up with an ecommimically viable process for re-treatment of the waste dump slags. In this study, a high pressure oidative acid leaching technology was applied for the treatment of dump smelter slags. The selective leaching of valuable metals with extractions of 97.4-99.5% for Ni, Co, Cu and Zn, and about 1% for iron was achieved. The produced residue containing less that 0.03% of heavy metals can be discarded safely. A poster about this project is available for viewing in Adobe Acrobat format (pdf).

 

Publications:

 

W. M. Curlook, V. G. Papangelakis and M. Baghalha, “Pressure acid leaching of non-ferrous smelter slags for the recovery of their base metal values,” Pressure Hydrometallurgy 2004, (Eds.  M.J. Collins and V.G. Papangelakis), 34th Annual Hydrometallurgy Meeting of CIM, CIM, Montreal, QC, pp. 823-838, 2004.

 

M. Baghalha, V.G.Papangelakis, W. Curlook, Factors affecting the leachability of Ni/Co/Cu slags at high temeperature. Hydrometallurgy (2006), doi:10.1016/j.hydromet.2006.07.007

 

Study of thermodynamic properties of aqueous systems

Irina Bylina

 

With the help of a calorimeter, heat capacities of salts and aqueous electrolyte solutions are measured. Another focus of this study is the enthalpy changes of minerals leached at elevated temperatures and pressures using a mixing cell.

 

Direct (in-situ) pH Measurement at High Temperature and Pressure in Hydrometallurgical Processes

 

Zoran Jankovic

 

A special once flow-through hydrothermal cell made of Titanium grade 5 provides the required high temperature and pressure environment. A flow-through YSZ (yttria stabilized zirconia) electrode is used as the pH sensor and a flow-through Ag/AgCl electrode as the reference. The silver/silver chloride element is placed at ambient temperature to prevent any thermal degradation. Computer software will be used to convert the voltage difference to pH values.

 

Publications:

 

V.G. Papangelakis, D.S. Seneviratne, Z. Jankovic, X.Y. Zhou, and S.N. Lvov, “pH measurements in High-Temperature Hydrometallurgical Systems,” Hydrometallurgy 2003 – Fifth International Conference in Honour of Professor Ian Ritchie (Eds. C.A. Young, A.M. Alfantazi, C.G. Anderson, D.B. Dreisinger, B. Harris and J. James), TMS, Warrendale PA, pp. 645-656.

 

S.N. Lvov, X.Y. Zhou, S.M. Ulyanov, Z. Jankovic, and V.G. Papangelakis, “In-situ pH Monitoring of High Concentration Sulfuric Acid and Acidified Geothermal Brines at Elevated Temperatures,” Pressure Hydrometallurgy 2004, (Eds.  M.J. Collins and V.G. Papangelakis), 34th Annual Hydrometallurgy Meeting of CIM, CIM, Montreal, QC, pp. 561-576, 2004.

 

 

 

PAST PROJECTS

 

Electrical Conductivity and Acidity of High Temperature Aqueous Sulphate Solutions. The main goal of this work is to investigate the inter-relationship between the measured conductivities and the acidities of high temperature aqueous sulphate solutions. To undertake this research, the conductivity cell developed previously (by Dr. Morteza Baghalha) will be used to measure the electrical conductivity of simulated laterite leach slurries at temperatures up to 250 °C. Acidities will be measured with the new pH sensor and estimated with chemical models. This will enable the development of a model capable of estimating the acidities of these high temperature sulphate solutions based on their conductivities. This work was undertaken by Mr. Ming Huang (now with AECL) as his Ph.D. research.

 

Hematite solubility in H2SO4 from 130-170 ºC and 230-270 ºC. In the study conducted by Mr. Michael Reid (currently with Vale Inco) as his Master's project, hematite solubility data was generated for 0.1-0.7 molal H2SO4 solutions at 130-170ºC and 230-270ºC. These measurements represent an improvement over previous experimental data due to better in-situ filtration of samples and inhibition of ferric iron reduction on titanium.

 

From Low Grade Ilmenite to TiO2 Using Hydrometallurgy: Kinetic Study on Leaching of Ilmenite in HCl/H2SO4. This research was undertaken by Mr. Gursaran Singh (now with Bantrel) as a Master's project.

 

Modelling of the nickel and cobalt kinetics during pressure acid leaching of laterites using Aspen plus 11.1 and OLI. This work was undertaken by Ms. Miranda Cheung (currently with Lafarge) as a Master's project.

 

Gypsum Scale Abatement in Continuous Hydrometallurgical Reactors. The objective of the work is to determine the rate of gypsum scale formation in continuous stirred reactors. Effect of pH, temperature, residence time are studied experimentally in order to elucidate the mechanism of scale growth, and eventually to reduce the scale in industrial reactors. Dr. Jeffrey F. Adams (now with Hatch) worked on this project for his Ph.D.

 

Development of Novel Experimental Techniques for Pressure Oxidation of Nickel Sulphide Ore. This state-of-the-art research was undertaken by Mr. James Brown (now with SGS-Lakefield) as a Master's project. A custom-made titanium autoclave (high-pressure reaction vessel) having three quartz windows is being equipped with a high-speed imaging system to monitor and quantify the production of elemental sulphur in real time under various reaction conditions. The wetting and adhesion force of liquid sulphur on the mineral surface will be measured by measuring the surface tension and contact angle.

 

High Temperature Thermodynamic Modelling of Autoclave Laterite Leaching Systems. This work was undertaken by Dr. Jesus Casas (University of Santiago, Chile) as a post-doctoral research project and later continued by Dr. Haixia Liu (now with Colt Engineering, Calgary).

 

Mathematical modelling of the pressure oxidation process of refractory gold-bearing ores and concentrates. This three-phase process was selected for case studies of the Population Balance application to the hydrometallurgical reactor modelling. The work was undertaken by Dr. Dmitri Rubisov (now with Bank of Montreal).

 

Kinetic Study of Gold Ore Cyanidation. The experimental work on establishing gold cyanidation kinetics was a M.A.Sc. Thesis of Ms. Peimeng Ling (now with Aker Kvaerner).

 

Development of the electrochemical kinetics models for gold ore cyanidation. The fundamental research findings in gold cyanidation were adapted and applied to describe the behaviour of particulate gold ores. The work was undertaken by Dr. Dmitri Rubisov (now with Bank of Montreal).

 

Neural Net modelling of aqueous metallurgical processes. The ability of neural nets to predict key process indices was successfully proved on the zinc electrowinning process. The established procedure of NN modelling was also applied to simulate another process (copper electrorefining). The work was undertaken by Dr. Dmitri Rubisov (now with Bank of Montreal).

 

Population Balance Modelling of a Particulate Dissolution-Precipitation Reaction Sequence: Hydronium Alunite Synthesis. The M.A.Sc. Thesis by Xiao Hong Ye (now with Honda) aimed at establishing the method of extracting kinetic data from experiments that involve simultaneous occurrence of several reactions. The work was based on the data obtained by Mr. B. Blakey.

 

Kinetics of Nickel Dissolution during Sulphuric Acid Leaching of Laterites. The dissolution kinetics for limonitic laterites were reported in the M.A.Sc. Thesis by Mr. Dimitrios Georgiou (currently with University of Patras, Greece) who also collected data on Co, Fe, Al and Mn behaviour during the process. These investigations were continued by Ms. J.-M. Krowinkel (currently with Budelco, The Netherlands) by experimentations with saprolitic laterites. The emphasis was on the behaviour of Ni, Mg and Co.

 

Scale Formation and Prevention during Sulphuric Acid Leaching of Limonitic Laterites. This experimental work is intended to establish the influence of the process parameters on the composition and rate of formation of scales in autoclaves for laterite leaching. The work was a M.A.Sc. Thesis of Mr. Panagiotis Perdikis (currently with Petrochemical Company, Greece).

 

Modelling and optimization of limonite leaching in continuous autoclaves. The high-temperature sulphuric acid leaching of nickeliferous laterites has been a major interest of the group over last five years. The results gained during the previous work were summarized and turned into a comprehensive process model capable of predicting the process parameters in both batch and continuous reactors. The work was undertaken by Dr. Dmitri Rubisov (now with Bank of Montreal).

 

Thermodynamics of Aqueous Solutions at High Temperatures. This work was undertaken by Dr. Morteza Baghalha (now Assistant Professor, Sharif University of Technology, Iran) and was his Ph.D. Thesis. Practical aqueous solutions at high temperatures are characterized by different experimental techniques. The techniques used to date include solubility measurements and conductivity measurements up to 250° C. Through this characterization, the complexes and the activity coefficient behavior of them "at temperature" are recognized.

 

Solubility of Hydronium Alunite under Direct Sulphuric Acid Pressure Leaching Conditions. This project constituted the M.A.Sc. Thesis of Mr. Zhu Xuetang (now PhD candidate, UofT). It is forming a basis for future modelling work, which needs accurate solubility data to verify and improve model predictions.

 

Ferric Scale Characterization and Dissolution during Sulphuric Acid Leaching of Limonitic Laterites. This experimental work established the influence of process parameters on the properties and rate of dissolution of scales in autoclaves for laterite leaching. This work constituted the M.A.Sc. project of Mr. Dimitrios Kambossos (now with Bantrel).

 

Synthesis and Solubility of Hydronium Alunite under Direct Sulphuric Acid Pressure Leaching Conditions. This project constitutes the M.A.Sc. Thesis completed by Mr. Brian C. Blakey (currently with GE-Research, Houston, TX, USA). The importance of the job is that hydronium alunite comprises a significant part of scales formed during pressure leaching of nickeliferous laterites.

Research

Important Announcement:

 

A Post Doctoral Fellow position is available in the areas of electrolyte thermodynamics and aqueous chemical processing.  The project deals with the development of databases for aqueous inorganic systems (minerals/salts in concentrated multi-component aqueous solutions) of interest to industrial applications at ambient and high temperatures-pressures. It has both computational and experimental parts. The project is supported by 5 Canadian and international metal producing companies. The position is available immediately and for one year initially. Interested candidates may direct questions and/or send CV and contact details for 2 referees to Prof. Papangelakis: vladimiros.papangelakis*AT*utoronto.ca