QUANTIFYING, REDUCING AND IMPROVING MINE WATER USE by Aaron James Gunson B.A., Mount Allison University, 1999 B.A.Sc., University of British Columbia, 2002 M.A.Sc., University of British Columbia, 2004 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Mining Engineering) THE UNIVERISITY OF BRITISH COLUMBIA (Vancouver) May, 2013 © Aaron James Gunson, 2013 ABSTRACT Water is vital to the mining industry; mines can require substantial amounts of water and are often located in some of the driest places on earth. Reducing water withdrawals and improving mine water use are key strategic requirements for moving toward a more sustainable mining industry. Mine water requirements often have significant technical, economic, environmental and political implications. This thesis quantifies global mine water withdrawals and discusses methods of improving mine water use by reducing water withdrawals and water-related energy consumption. The thesis is composed of four main sections. First, two methods are proposed to calculate global mining water withdrawals by commodity. One method is based on the amount of water required to process a tonne of ore and the other is based on the amount of water required to produce a tonne of concentrate. A large database was created, compiling data regarding ore production, commodity production, commodity prices, and mine water withdrawals between 2006 and 2009. The study estimates that global water withdrawals range from 6 to 8 billion m3 per annum. Second, the thesis presents a case study on the challenges faced and lessons learned during the design, start-up and modification of the water systems of a large copper mine site. Third, the thesis identifies multiple mine water reduction, reuse and recycle strategies that have been implemented around the world. A model is developed and used to show the potential impact of these strategies. The results of the modelling show how a hypothetical mine could reduce water withdrawals from 0.76 m3/t to 0.20 m3/t of ore processed or lower. In particular, the combination of ore pre-concentration and filtered tailings disposal reduced water consumption by over 74% of the base case. Finally, this thesis describes and demonstrates a method of determining the lowest energy option for a mine water network. The method uses a linear programming algorithm to compare options for matching water sources with consumers at mine sites. An example illustrates the method and shows how mine water system energy requirements can be reduced by over 50%. ii PREFACE Thus far the research undertaken for this dissertation has generated two journal publications and five refereed conference papers. In all cases, as the first author, I was primarily responsible for the research design, data collection and analysis, manuscript preparation and writing. Dr. Bern Klein, Dr. Marcello Veiga, Dr. Scott Dunbar, and Dr. Ward Wilson, as members of my supervisory committee, provided input, through advice and editing assistance. The publications are as follow: Gunson, A. and K. Wood. 2008. Raw Water Supply: The Experience of Cerro Verde. In CMP 2008 Proceedings. Ottawa. Gunson, A, Klein, B., and Veiga, M. 2008. Improving Mill Water System Design, In Proceedings WIM 2008, Santiago. Gunson, A., Wood, K., Klein, B., and Veiga, M. 2008. Estimating Water Demand and Availability for Open Water-based Mill Cooling Systems, In Proceedings of XXIV IMPC, Beijing. Gunson, A, Klein, B., and Veiga, M. 2010. Improving Mine/Mill Water Network Design by Reducing Water and Energy Requirements. In CMP 2010 Proceedings. Ottawa. Gunson, A, Klein, B., and Veiga, M. 2010. Estimating Global Water Withdrawals due to Copper Mining. In Proceedings WIM 2010, Santiago. Gunson, A. Klein, B., Veiga, M., Dunbar, S. 2010. Reducing mine water network energy requirements. Journal of Cleaner Production, Volume 18, Issue 13, September 2010, Pages 1328-1338. iii Gunson, A. Klein, B., Veiga, M., Dunbar, S. 2012. Reducing mine water requirements. Journal of Cleaner Production, Volume 21, Issue 1, January 2012, Pages 71-81. Additional assistance was provided by others as follows: “Raw Water Supply: The Experience of Cerro Verde.”, was reviewed and commented on by Ken Wood, my mentor at Fluor Canada. The paper was also reviewed, commented on and approved by John Marsdon, John Broderick, and Peter Faur, of Freeport McMoran Copper and Gold and Dave Dicaire, of Fluor Canada. In addition, Ian Orford, 1st Vice Chair of the Canadian Mineral Processing Conference, 2008, provided editing recommendations on the structure of the paper before final acceptance. The case study describes the design, pre-operations testing, start- up and upgrades to the Cerro Verde Primary Sulfide Project (CVPSP) water system. In addition to being the primary author, I worked as a process specialist with Fluor Canada and Fluor Daniel International on the CVPSP from November 2004 until March 2007, from the beginning of detailed engineering to the completion of the water system upgrade. I was the primary process designer for the CVPSP water systems, with responsibilities including: Creating and updating the site water balance, using data from the project mass (metallurgical) balance, existing site data and data from MWH Global on the proposed tailings storage facility; Compiling information about the available water quality based on SMCV environmental monitoring data; Compiling information from vendors about water requirements for mechanical and electrical equipment; Designing process flow sheets and piping and instrumentation diagrams for the plant water systems and providing process data for mechanical equipment datasheets; iv Writing the water systems process control philosophy and operating manuals; Leading the pre-operational testing and wet testing of the plant water systems; and Leading efforts to upgrade the fresh water system, including drafting evaluations of available options, completing detailed design of the process modifications, commissioning the modifications and training SMCV operators on how to operate the system. “Improving Mill Water System Design” was reviewed and commented on by an anonymous reviewer for the Water in Mining Conference in 2008. “Estimating Water Demand and Availability for Open Water-based Mill Cooling Systems” was reviewed, commented on, and approved by Ari Partanen of Freeport McMoran Copper and Gold. It was also reviewed and commented on by an anonymous reviewer for the International Mineral Processors Conference in 2008. “Improving Mine/Mill Water Network Design by Reducing Water and Energy Requirements” was reviewed and commented on by Dominic Fragomeni, 1st Vice Chair of the Canadian Mineral Processing Conference, 2010. “Estimating Global Water Withdrawals due to Copper Mining” was reviewed and commented on by an anonymous reviewer for the Water in Mining Conference in 2010. “Reducing mine water network energy requirements” and “Reducing mine water requirements” were reviewed and commented on by anonymous peer reviewers and Gavin Hilson, Subject Editor, Journal of Cleaner Production. Chapter 2, Literature Review, integrates the literature reviews undertaken during the research of all of the above papers in addition to further relevant publications. v Chapter 3, Methodology, integrates the methodology descriptions of all the above papers in addition to outlining the methodology used in Chapter 4, Estimating Global Mine Water Use. Chapter 4, Estimating Global Mine Water Use, is partially based on concepts developed in “Estimating Global Water Withdrawals due to Copper Mining,” but is largely composed of material not previously published. Chapter 5, Case Study – Cerro Verde Concentrator Fresh Water System, is primarily based on the papers, “Raw Water Supply: The Experience of Cerro Verde,” “Improving Mill Water System Design” and “Estimating Water Demand and Availability for Open Water-based Mill Cooling Systems.” Chapter 6, Reducing Mine Water Requirements, is closely based on the paper “Reducing mine water requirements.” Chapter 7, Mine Water Network Design, is closely based on the paper “Reducing mine water network energy requirements.” However, it also includes a previously unpublished section integrating and building on the results of the paper “Reducing mine water requirements.” No ethics certificates were required or obtained for this dissertation. vi TABLE OF CONTENTS ABSTRACT ................................................................................................................................... ii PREFACE ..................................................................................................................................... iii TABLE OF CONTENTS ............................................................................................................. vii LIST OF TABLES ...................................................................................................................... xiii LIST OF FIGURES .................................................................................................................... xvi LIST OF ABBREVIATIONS AND SYMBOLS ..................................................................... xviii ACKNOWLEDGEMENTS ....................................................................................................... xxv DEDICATION ......................................................................................................................... xxvii 1. INTRODUCTION ................................................................................................................