IMPROVING EFFICIENCIES: THE ROLE OF PROCESS AUDITS MINE AFRICA BREAKFAST, PDAC 2015 Mike Hallewell B.Sc., C.Eng. Business Development Manager
COMMITMENT TO SERVICING AFRICA s NEEDS Mines in Africa SGS in Africa 2
TYPICAL PLANT ISSUES n Plant management are pinching our gold!!?? n Our recovery is bad, must be the ore type!!?? n We cannot achieve recovery or concentrate grade!!?? n We cannot make throughput concentrate grade or recovery!!?? n Poor manual sampling, sample preparation at mine and plant Installed automatic samplers and adapted metallurgical accounting systems to back calculate head assay. n Found level controllers on flotation cells defective. Redesigned level controller measurement n Found ore type had changed mineralogically Introduced new Operational Practices. n Plant Design Infrastructure NOT as Feasibility Study recommended Capex Savings Subsequently Retrofitted at much greater cost to business due to metal losses incurred. 3
GLOBAL TREND WHY INCREASE EXISTING OPERATIONAL EFFICIENCIES? n This downturn is different n Financial support, specifically for greenfield projects is at an all time low n Mining industry performance is being scrutinised financially like never before n Risk mitigation is increasing mine development costs and timelines. n The global industry is forced to maximise return on investment n Post feasibility optimisation programs now occurring n Mining sector needs to innovate n Maximisation of metal recoveries and minimisation of costs is vital n Measurement of appropriate operational metrics is essential n The skills available in the next 10 years will be in shorter supply n This is why improving efficiencies is a key focus today SGS have significant skills in this area which compliment our current strong On site laboratory business which is very strong in Africa Commercial geochemical, metallurgical/mineralogical and trade business in Africa 4
WHAT IS A PROCESS AUDIT? 1. Review of feasibility study flowsheet design and testing 2. Review of metallurgical accounting 3. Metallurgy and mineralogy 4. Efficiency & metallurgical benchmark testing 5. Review of throughput, power usage and plant downtime 6. Review of instrumentation and process control 7. Review of operational practices 8. Review of health and safety 5
OPERATIONAL BEST PRACTICES In remote areas- Keep it simple!! n Critical points n Key measurements and KPI s n Data tracking and reporting n Communications up down and across n Design systems so that the easiest way to operate is the correct way. n Efficient plants are generally easy to operate. n One common operating strategy for all shifts NOT different strategies for each shift!! USGS Core Repository - Denver Plants run 24hrs a day not 8hr shifts!! 6
IMPROVED PROCESS CONTROL & AUTOMATION The future is advanced system control where applicable n Throughput and Recovery with lower grade deposits is key to project success Advanced control enables the process to self optimise itself 24/7. Always adds value to grinding circuit constrained operations n Real time measurement of KPIs is increasingly vital to ensure project success. n Data is required quicker and faster to speed up decision making processes where automation can not be applied. n Removes sensitivity of operations from human resources especially in remote geographically challenging areas. 7
MUPANE GOLD MINE, BOTSWANA 8
INITIAL FLOWSHEET n In Summary Crush Grind Float Carbon In Leach (CIL) Carbon elution, regeneration and EW Gold pour Tailings 9
THE (FORMER) ISSUE AT MUPANE The situation n 10% Increase in Tonnes 2010 n Pseudo CIP Circuit 2010 n Ore changes (oxide to sulphide) The problem n High soluble gold losses n Poor carbon elution The investigation n Diagnostic approach Carbon activity very poor (less than 10% mid-circuit & only 40% after regeneration) n Small scale testing and CIL modelling Simulate plant, model CIL performance Assess n Plant testing Organic poisoning of the carbon? Perhaps by flotation reagents? Regeneration efficiency? Bypass flotation for test case Improve kiln (higher temp, longer res time) 10
SGS CIP-CIL MODELLING METHODOLOGY n Rheology testwork to optimize pulp density n Determine gold leaching kinetics n Determine kinetics of gold adsorption on carbon n Model data-fitting Plug kinetic leaching and adsorption equilibrium constants (k s, k, K) into the rate and mass balance equations n Results Gold concentration profiles in the ore, on the carbon and in solution across multi-stage adsorption circuits. Plant design optimization based on metallurgical performance for various plant design and operating scenarios. 11
MODEL PARAMETERS INPUTS n Plant throughput (tonnage, pulp density, gold head grade). n Leach and adsorption constants. n Number and size of leach and adsorption tanks. n Desired concentrations of gold Barren solution On Loaded carbon, and on Eluted carbon. OUTPUTS n Amount of carbon needed for each stage. n Loaded carbon advance rate to elution and regeneration. n Gold lock-up in the plant on the carbon. n Concentration profiles of gold in solution in solids and on the carbon in each stage of the multi-stage circuit. 12
CIL PLANT PERFORMANCE 2009/2010 Analyzed Gold in solution (mg/l) Gold on carbon (g/t) (carbon activity) Gold in the ore (g/t) (feed grade) Q1/09 flotation Q2/09 no flot 2010 no flot Q1/09 Q2/09 2010 Q1/09 Q2/09 2010 CIL feed 2.20 2.36 1.90 CIL 1 0.76 0.18 0.25 1917 2044 2221 1.84 0.96 0.39 CIL 2 0.40 0.11 0.11 1467 1208 1572 0.71 0.80 0.28 CIL 3 0.34 0.09 0.051 1275 980 927 0.62 0.56 0.24 CIL 4 0.21 0.04 0.027 923 616 696 0.58 0.61 0.23 CIL 5 0.13 0.027 0.016 680 363 485 0.47 0.53 0.22 CIL 6 0.09 0.019 0.012 566 377 409 0.27 0.48 0.22 Recovery,% 76.0 80.3 84.5 13
BENEFITS n Sensitivity Analysis shows that a 12.5% decrease in processing costs increases the pretax NPV by about 6%. Reagent and power costs decreased because flotation pre-concentration was no longer used. n Gold recovery increased from 76% to 80.4% n $2.9 million to the bottom line year on year no capex costs n No flotation Plant - Opex savings increasing NPV 14
PROCESS AUDITS PROVIDES COMPETITIVE EDGE n Thinking globally n Acting locally n Using best practices n Cutting Edge Technologies n Enhancing Quality n Improving Productivity n Ensuring Compliance n Reducing Risk 15
n THANK YOU! 16