Integrated Mining, Pre-Concentration and Waste Disposal Systems for the Increased Sustainability of Hard Rock Metal Mining
Total Page：16
File Type：pdf, Size：1020Kb
INTEGRATED MINING, PRE-CONCENTRATION AND WASTE DISPOSAL SYSTEMS FOR THE INCREASED SUSTAINABILITY OF HARD ROCK METAL MINING By ANDREW SHERLIKER BAMBER, B.Sc. (Mechanical Engineering) University of Cape Town, 1993 Pr. Eng. (Engineering Council of South Africa), 1999 M.A.Sc. (Mining & Mineral Processing) University of British Columbia, 2004 A THESIS SUBMITTED IN FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Doctor of Philosophy in THE FACULTY OF GRADUATE STUDIES (Mining Engineering) UNIVERSITY OF BRITISH COLUMBIA (Vancouver) April 2008 © Andrew Sherliker Bamber 2008 Abstract In the hard rock metal mining industry, both in Canada and globally, a decreasing number of economic mineral deposits are found at shallow to medium depth, and most of the deposits that remain are close to sub-economic and are required to be mined at high tonnages in order to show a return. The majority of remaining deposits are presented in challenging geological or geotechnical settings making the deposit sub-economic. The integration of ore pre-concentration and waste disposal functions into the hard rock metal mining system is proposed as a novel interpretation of Mine-Mill Integration for improving the economics and environmental impact of exploiting such deposits. The proposed approach seeks to reject waste as early as possible in the mining cycle, and safely dispose of it as backfill. This is proposed as a ‘Lean’ alternative to improving the economics of mining simply by increasing the throughput. ‘Lean’ philosophy seeks to design out overburden, smooth production, and eliminate waste from the manufacturing system. It is suggested that the proposed approach addresses all three areas, and is thus an important strategy to be considered for mining companies wishing to simultaneously improve their efficiency, economics and environmental performance, thus increasing their sustainability. Technologies specific to the success of the approach including pre-concentration systems, composite fill systems, and continuous mechanized mining methods are discussed. The impacts and benefits of integrating these technologies are defined and quantified through research, testwork, systems design and analysis. Custom geo-metallurgical evaluation tools incorporating mineralogical, metallurgical and geotechnical methods have been developed to assess ores in terms of their potential for the adoption of the proposed approach. A computerized parametric evaluation model has been developed to quantify the potential impacts and benefits using data from these evaluations. Data from over 26 case studies combined with the literature indicates that the opportunity for ore pre-concentration appears to be a general case in hard rock ores. A wide range of impacts and benefits arising from this potential have been identified and quantified through the research, indicating positive overall outcomes for the majority of cases studied. ii Table of Contents Abstract…………………………………………………………………………… ii Table of Contents……………………………...………………………………….. iii List of Tables……………………………………………………………………... viii List of Figures…………………………………………………………………….. x List of Symbols……………………………………………………………............ xiv Glossary…………………………………………………………………………... xvi Acknowledgements………………………………………………………………. xx Chapter 1 – Introduction and Thesis Outline………………………............ 1 1.1 Introduction………………………………………………………………….. 1 1.2 Significance of the Research……………………………………...….............. 7 1.3 Research Contribution……………………………………………………….. 8 1.4 Thesis Outline………………………………………………………………... 8 Chapter 2 – The Application of Integrated Mining, Pre-concentration and Waste Disposal Systems in the Hard Rock Metal Mining Industry………………………………………………………………………….. 10 2.1 Introduction………………………………………………………………….. 10 2.2 The Application of Lean Manufacturing Concepts to the Hard Rock Metal Mining System……………………………………………………………….. 13 2.3 Ore Pre-concentration as an Example of Lean Manufacturing in Mining……………………………………………………………………….. 14 2.4 ‘Lean’ Case Study – Xstrata Nickel Ontario Operations…………………….. 21 2.5 Conclusions…………………………………………………………………... 25 Chapter 3 – Enabling Technologies………………………………………….. 27 3.1 Introduction…………………………………………………………………… 27 3.2 Process Technologies…………………………………………………………. 29 3.2.1 Ore Pre-concentration by Comminution and Size Classification…………... 32 3.2.1.1. Development of the Concept…………………………………………… 32 3.2.1.2. Testwork at UBC………………………………………………………. 34 3.2.2 Pre-concentration by Sorting……………………………………………….. 37 iii 3.2.2.1 Sorting Practices in the Minerals Industry……………………………… 37 3.2.2.2 Radiometric Methods…………………………………………………… 41 3.2.2.3 X-Ray and Laser Methods………………………………………............ 42 3.2.2.4 Optical Sorting………………………………………………………….. 42 3.2.2.5 Conductivity Sorting……………………………………………………. 43 3.2.3 Pre-concentration by Dense Media Separation……………………………... 45 3.2.4 Coarse Particle Flotation Techniques for the Pre-concentration of Base Metal Sulphide Ores………………………………………………………… 48 3.2.4.1 Development of the Concept……………………………………………. 48 3.2.4.2 Theoretical Basis………………………………………………………... 50 3.2.4.3 Scoping Testwork Results………………………………………………. 53 3.3 Waste Disposal Technologies………………………………………………… 56 3.3.1 Background………………………………………………………………... 56 3.3.2 Development of A ‘Rocky’ Paste Fill For Use With Underground Pre- Concentration Systems…………………………………………………….. 59 3.3.3 Fill Preparation and Delivery Systems…………………………………….. 62 3.4 Interfacing the Technologies with the Mining Activity………………………. 65 3.4.1 Cut-and-Fill Mining……………………………………………………….. 69 3.4.2 Open Pit Methods…………………………………………………………. 71 3.4.3 Block Caving………………………………………………………………. 72 3.4.4 Open Stoping Methods……………………………………………………. 75 3.4.5 Room and Pillar……………………………………………………............ 76 3.5 Conclusions……………………………………………………………............ 77 Chapter 4 –Experimental Methods for the Geo-metallurgical Evaluation of Ores for Pre-concentration and Waste Disposal ………… 78 4.1 Introduction……………………………………………………………….. 78 4.2 Mesotextural Evaluation, Fragmentation and Liberation Analysis……….. 78 4.3 Separability Evaluation……………………………………………………. 84 4.3.1 Dense Media Separation Testwork…………………………………… 84 4.3.2 Optical Characterization……………………………………………… 85 4.3.3 Conductivity Evaluation……………………………………………… 89 4.3.3.1 Testing of the INCO 'B2' Sensor……………………………….. 90 iv 4.3.3.2 Development of the MineSense B2 ‘MkII’ Sensor…………….. 93 4.4 Grinding Work Index Testing……………………………………………… 97 4.5 Additional Geotechnical, Geo-metallurgical and Rheological Testwork….. 97 4.5.1 Geotechnical Characterization of Rejects…………………………... 97 4.5.2 Mix Design and Testing…………………………………………….. 99 4.5.3 Rheological Tests……………………………………………............ 100 4.6 Conclusions…………………………………………………………............ 101 Chapter 5 – A Parametric Model for the Economic Evaluation of Pre- concentration as a Lean Manufacturing Technique in Hard Rock Metal Mining……………………………………………………….................................. 102 5.1 Introduction…………………………………………………………………... 102 5.2 Evaluation Methodology……………………………………………………... 103 5.3 Model Assumptions………………………………………………………….. 107 5.4 Cost and Revenue Impacts……………………………………………............ 108 5.4.1 Operating Cost Impacts……………………………………….. 108 5.4.2 Estimation of Capital Costs for Hard Rock Mines…………… 111 5.4.2.1 Estimation of Open Pit Mining Costs…………………………............ 111 5.4.2.2 Estimation of Underground Mining Costs……………………………. 112 5.4.2.3 Estimation of Plant & Surface Infrastructure Capital Costs………….. 114 5.4.2.4 Adjustments for Variations in Mine Capacity and Effect of Inflation……………………………………………………….………. 116 5.4.3 Revenue Impacts………………………………………………. 117 5.4.3.1 Impacts on Recovery…………………………………………………... 117 5.4.3.2 Variations in Metal Price………………………………………............ 120 5.5 Impact of Cost Variations on Cutoff Grade, Resources and Reserves………. 122 5.5.1 Estimating the Ore Reserve…………………………………… 122 5.5.2 Cost – Cutoff Grade Interactions……………………………... 126 5.5.3 Cutoff Grade – Tonnage Interactions for an Idealised Resource………………………………………………………. 128 5.6 Impact Valuation and Evaluation Methodology……………………………... 131 5.7 Conclusion……………………………………………………………............ 136 v Chapter 6 – Integrated Mining, Processing and Waste Disposal Case 137 Studies…………………………………………………………………………… 6.1 Introduction…………………………………………………………………… 137 6.2 Gold Ores……………………………………………………………………... 138 6.3 Lead-Zinc Ores of the Mississippi Valley Type………………………............ 139 6.4 Pre-concentration of Copper Porphyry Ores………………………………….. 142 6.5 Footwall and Contact Type Ores of INCO’s Sudbury Operations……............ 146 6.6 Polymetallic Base Metal Sulphide ores of Xstrata Nickel’s Ontario Operations…………………………………………………………………….. 147 6.6.1 Preliminary Core Evaluations for 2 Mines……………………………….. 148 6.6.2 Phase II Study for 9 Ores of Xstrata Nickel’s Ontario Operations……….. 153 6.6.2.1 Metallurgical Results…………………………………………………. 155 6.6.2.2 Investigation of Waste Disposal Aspects…………………………….. 159 6.6.2.3 Rheological Evaluations of Fill Mixes……………………………….. 165 6.6.2.3 Grinding Index Testwork…………………………………………….. 165 6.6.3 Evaluation of Impacts on Energy Usage at Xstrata Nickel’s Ontario Operations…………………………………………………………........... 167 6.6.3.1 Impact of the Pre-concentration Step…………………………………. 170 6.6.3.3 Impacts on Hoisting Energy…………………………………………... 170 6.6.3.4 Impacts on Surface Haulage………………………………………….. 171 6.6.3.5 Impacts on Grinding and Overall Beneficiation of the Ore…………... 172 6.6.3.6 Impacts on Overall Energy Usage……………………………………. 174 6.6.4 Conclusions……………………………………………………………….. 175 6.7 Low Grade Ultramafic Ni Ores of the Thompson