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By S Davidge, J Pile, R Schumann, E Kepe, W Stewart, M Ridd, B Rathi

Geographical constraints, including steep terrain and high rainfall, at the Ok Tedi copper-gold mine in PNG’s Western Province present Ok Tedi Mining Limited (OTML) with significant challenges in mine waste management. Waste management includes discharge of tailings into the local river system and storage of waste rock from the mine pit in waste rock dumps which erode into the river system. Copper bearing skarn mineralisation is associated with a massive sulfide (mainly pyrite) deposit. Consequently, waste rock and tailings can contain significant amounts of pyrite. Without appropriate management, these waste streams represent a risk of producing acid and metalliferous drainage (AMD) when discharged to the river system. Throughout the life of the project, OTML have developed evolving strategies to manage mine wastes and mitigate AMD.

Aug 2, 2023

By A Fern, A Hawkes, o, W Smith, K Mee

Serious Injury and Fatality (SIF) prevention remains a priority focus within high-risk industries sector. A major mining operation sought to strengthen their approach to the management of high-risk activities through an in-depth review of all historical incidents that had serious injury or fatality potential (SIFp) events (sometimes known as hi-potential events). The analysis found that the organisation invested a disproportionate level of resources, time and effort on low consequence incidents with a high proportion of SIFp incidents going under the radar. It was found that 76 per cent of SIFp incidents were rated in moderate or lower risk categories and conversely, almost half of those incidents with a ‘serious risk’ rating had little or no potential for a serious outcome. As a result of this project, the operation engaged in a renewed focus on critical risk management and enhanced its operating cadence in critical risk for the workforce. This included bow tie analysis, an update to critical risk standards and increased workforce engagement in the use of critical control verifications in the field. Data analytics with lead and lag indicators continue to provide senior leadership team and risk owners with an understanding of exposure for SIFp and control effectiveness. The audience will take away learnings from a real-world case study that provides data-driven insights of the human, local and organisational factors contributing to incidents with SIF potential. In addition, participants will understand the steps taken to categorise and analyse this incident data and the initiatives currently being implemented by the organisation as a result.

Apr 16, 2024

By R Berry, S G. Walters, J A. Hunt, D Collett

The texture of an ore type is fundamental in understanding the metallurgical behaviour of an ore. This study will show examples of how quantified textural attributes (mineral shape, grain size and mineral association) can be obtained from automated and scanning electron microscope (SEM)-based microscopy and utilised using advanced image processing techniques. Examples will be shown of integrating quantified and semi-quantified meso- and macro-scale textural attributes as well as how they relate to texture-based visual logging systems. The implications of texture for processing behaviours such as comminution, liberation and recovery will be discussed. This research is part of a major collaborative geometallurgical project undertaken at the Centre of Excellence in Ore Deposits (CODES, University of Tasmania) and the Julius Kruttschnitt Mineral Research Centre (JKMRC, University of Queensland). The authors wish to acknowledge financial support and permission to publish from the sponsors of the AMIRA P843 GEMIII project.

Jan 1, 2008

By J Sigda, T Jones, D Staggs, J Ewing, C Cheng, J Pickens, S Paulka

Mine-derived solutes from Energy Resources of Australia’s (ERA’s) Ranger uranium mine have been closely monitored for decades. Ranger is surrounded by the Northern Territory’s Kakadu National Park and is upstream of Ramsar convention wetlands. Modelling of groundwater flow and solute egress from mine wastes to surface waters has helped ERA successfully assess closure options and secure intermediate regulatory approvals during the site closure process. Potential environmental impacts were assessed using groundwater modelling in support of three ERA applications involving disposal of tailings-derived mine waste. Model results were an important part of the basis for obtaining regulatory approval. Three case studies are presented describing the three applications and how the groundwater modelling supported approval of the applications. For case study #1, INTERA supported ERA in addressing stakeholder concerns in 2017 regarding two aspects of tailings deposition in Pit 3. The first was the potential for flow of tailings fluid into the surrounding formations during tailings deposition. The second was the difference in post-closure magnesium (Mg) loading to surface water for two tailings deposition scenarios. INTERA developed a two-dimensional (2D) model that showed excess tailings pore pressures would not cause outflow and solute egress from the pit during deposition. INTERA’s three-dimensional (3D) models demonstrated that post-closure Mg loading to creeks for both tailings scenarios differed marginally and would be a small fraction of natural creek Mg loads. The modelling results helped avoid delays in completing tailings deposition driven by stakeholders’ environmental concerns. Case study #2 consisted of supporting ERA’s 2019 request for approval to change the tailings deposition method and final tailings level in Pit 3. INTERA’s model results for the permitted and proposed deposition methods showed minimal differences in post-closure Mg loading to creeks. The model results helped ERA obtain the needed approval for the tailings deposition method and water and tailings levels in Pit 3. For case study #3, INTERA modelled the comparative impacts from leaving the entire contaminant plume from the temporary tailings storage facility (TSF) in situ or excavating a portion of the contaminated material from beneath the TSF floor and placing it in Pit 3. The modelling results supported an approved TSF contaminated material application important for ERA to stay on schedule and minimise both closure costs and environmental impacts.

Jul 1, 2021

By J Dyt, S Lyons

In the mining industry, crusher-related incidents have led to 15 reported deaths in Australia, New Zealand, and the USA between 1998 and 2007 (NSW Government Resources Regulator, 2024). The majority of these fatalities occurred during routine crusher maintenance tasks. A survey of quarry and mine site maintenance staff was completed to ascertain what they thought of such safety device to understand if beneficial and if so reasons if unused. Overall, findings show, staff perceived risks differently, cost, familiarity, device awareness and not front of mind, influenced adoption. This underscores the importance of asking the right questions involving maintenance and safety staff to lead to more proactive risk assessment.

Apr 16, 2024

By G H. Park, Y J. Jun, J H. Park

The carbon solubility of the CaO-Al2O3-FeO-SiO2-MgO slag, the main system formed in the Ruhrstahl-Heraeus (RH) vacuum degasser, was measured at 1873 K to understand the effect of slag compositions on the carbon contamination in the ultra-low carbon (ULC) steels. The stable form of carbon was demonstrated to be carbonate by plotting the log [(wt%C)/aC] ratio against the log p(O2) which ranged -11 < log p(O2,atm) < -9. The carbon solubility of the CaO-Al2O3-FeO-SiO2-MgO slag can be estimated using thermodynamic model. The distribution ratio of carbon increased with increasing concentration of FeO due to the FeO reduction reaction and increased basicity of slag. The carbonate capacity of the CaO-Al2O3-FeO-SiO2-MgO slag can be expressed as a linear function of the activity of lime and the optical basicity.

Jun 19, 2024

By J Ross

The foundation of effective leadership is communication. You can have all the leadership theories, models and training you want, but in the end it is all about leaders talking to, listening to and understanding the point of view of those below and above them.The foundation of effective safety is peoples’ behaviours. Every incident, every near miss and every safe act comes down to what one person does and how that affects themselves and others. We tend to focus these behavioural considerations on the people at the ‘coal face’, those most in harm’s way. But it is the individual behaviours of everyone in the organisation, particularly those at the top, which are just as (if not more) important. The foundation of effective safety leadership in the mining industry is that it starts at the top, with the individual behaviours of leaders. The behaviours of each and every leader will be reflected in their teams. And where their teams are made up of leaders, these leaders will pass these behaviours on to their teams and so on. It’s the sum total of what people see their leaders do and what they do as a result, that creates the ‘culture’ of the business – and it’s this culture that makes or breaks how safely people work.

Mar 21, 2011

By X Y. Ma, X G. Tian, P F. Zhang, T B. Zhao, Z H. Li, Z Y. Fu

This study analysed the fracture characteristics and movement process of goaf roofs under the condition of gangue backfilled mining, based on the engineering conditions of Tangshan Mine F5001 gangue backfilled working face. The inclined borehole detection method is adopted to conduct long-term and fixed-point detection of the roof stability. The distribution characteristics of mining-induced cracks in the roof are described quantitatively based on the crack density, and a similar model test method is used to assist the analysis of the roof movement under the control of gangue backfilled mining using stress sensors and digital speckle deformation field monitoring. The results show that under the condition of gangue backfilled mining, structural cracks in the roof typically appear at the boundary of rock strata. The appearance of cracks is related to the rock strata where they are located. Structural cracks appear in the form of single cracks ahead of the working face and develop into structural cracks in the goaf. The roof movement of the coal seam develops in five stages: fracture incubation, crack extension in advance, dense fracture development, steady fracture expansion, and roof stability. Separation forms the primary component of the roof subsidence, accounting for more than half of the subsidence value. The separation generally extends over a long distance along the strike, and vertical crack-intensive areas appear in the roof above the cut-off and stop line. The findings of this study provide a theoretical basis to support designs of backfilled mining and upgrading of hydraulic supports in working faces.

Nov 29, 2022

By M Recabarren, A Echeverria, J Ronda, J I. Guzman, R Dodds, G Juarez, E Vila-Echague

A strategic mine plan is a fundamental part of any mining operation. It must provide a realistic and operative extraction and processing schedule, and yield the highest value for the business. For open pit mines, the problem can be modelled as a set of blocks representing the deposit, for each of which we need to decide if it is going to be mined, if so, when and where it will be sent (process, stock or dump).This problem can be proven to be of NP-Hard complexity. The traditional approach used by mining engineers to tackle this complexity is to separate the problem into more tractable components, solving each separately. The first step is to use the Lerchs-Grossman (LG) algorithm to obtain the final pit limit, as well as a set of optimised pit shells (nested pits), using different input prices. Then, using this input, operational phases are designed. Third, the set of phases can be used as an input for a phase-bench style optimisation, usually using a mathematical programming-based algorithm.There are, however, several problems with this approach. First, dividing the problem into simpler parts has the consequence that any compromises made at early stages limit the potential value left for the following steps. Second, LG is a static algorithm, with no concept of the time-value of money, capacity limits, opportunity costs, etc. Phase design is essentially a manual step, for which nested pits provide insufficient information in practice, and therefore the quality of the result in terms of potential net present value (NPV) depends strongly on the experience and expertise of the designer. This means that key input data such as commodity prices, different processes capacities and mine movement limits, are considered only at scheduling, when there is little room for optimisation. This sequential approach limits the potential value in each step, where a simplified problem is addressed, instead of addressing the real, and more complex problem, which is dynamic and should be solved as a whole.We present in this paper an algorithm, and its commercial software implementation, that addresses the dynamic problem as a whole, simultaneously and automatically creating a high-value strategic mine plan that adheres to basic operational constraints, determining dynamic cut-off grades and delivering a set of phases which can serve as a much stronger guide than nested pits for the final design. We discuss some of the key elements of the algorithm and propose a new methodology for strategic mine planning, where phase design dynamically responds to mining strategy definition. Results using different mining and operational parameters on a fictitious copper deposit are used as a demonstrative example.CITATION:Juarez, G, Dodds, R, Echeverria, A, Guzman, J I, Recabarren, M, Ronda, J and Vila-Echague, E, 2014. Open pit strategic mine planning with automatic phase generation, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 147–154 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By S Bright, M J. Masamvu, E K. Chiwandika, S Dandi, S M. Masuka

The depletion of high-grade hard and lumpy chrome ores has forced Zimbabwean ferrochrome producers to resort to low-grade friable ores that have an average of 28 per cent fines against a set limit of 12 per cent. Submerged open arc furnaces currently in use are associated with eruptions within the furnace because of the high amounts of fines, high energy consumption, as well as high SO2 and CO2 emissions. Traditionally employed agglomeration methods such as pelletising and the use of coke in the furnace have been discarded because of the pressure to lower operational costs and to achieve higher profit margins. This research aims to develop a method to incorporate lowgrade friable ore fines and unprocessed coal into production while lowering CO2 and SO2 emissions through a closed direct current (DC) arc furnace. The closed DC arc furnace could incorporate the friable ores and coal while maintaining above 90 per cent reduction rates. Preliminary findings also show that energy consumption could be reduced by up to 35 per cent by incorporating a pre-heating and pre-reduction system using the flue gases from the furnace. In the proposed circuit, the cost of production per ton of ferrochrome might be potentially lowered by an average of 30 per cent.

Jun 19, 2024

By M Bettison, R Wright, N Taylor

The primary mine planning focus during early study phases of future mining projects is Life of Asset ore production and grade quality, this will always be the situation. While waste schedule optimisation is generally considered in the latter study phases nearing execution for a limited number of schedule periods only and not a true optimisation considering all attributes such as waste destination location, design, cycle time and closure. This can be particularly applicable in large multi-pit bulk mining operations where one approach to meet Life of Asset ore tonnes and grade targets has been to maintain pit development flexibility resulting in large open pit areas and substantial expit Overburden Storage Area (OSA). The value opportunity is to develop a Life of Asset waste schedule source-to-destination optimisation prior to mine development considering all applicable attributes and routinely review throughout the Life of Asset taking account of improved ore and waste knowledge.CITATION:Taylor, N, Wright, R and Bettison, M, 2018. Utilising mine planning to deliver closure landforms through productive movement, in Proceedings Life-of-Mine 2018, pp 96–99 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By A Specht, A Müller, V Montenegro, S Winkler, E Klaffenbach, A Schmidt

In the process of primary copper smelting in flash smelting furnace (FSF), the ratio of iron to silica (Fe/SiO2 mass ratio) primarily determines the slag viscosity and magnetite formation. Viscous slag does not only cause difficulties in daily operation, such as in tapping, it also increases the copper losses to slag. Thus, keeping the Fe/SiO2 mass ratio at the desired level is an important aspect of FSF and slag cleaning furnace (SCF) operation. In this study, the improvement of the Fe/SiO2 mass ratio was conducted in two steps: First, the optimal Fe/SiO2 mass ratio was derived based on thermodynamic data. Based on this analysis, appropriate control limits were determined. Second, this range of favourable Fe/SiO2 mass ratios was implemented into operation by an advice-based control system, which suggests the addition of silica based on the analysis of SCF slag. As this approach was successful, the same advice-based control system principle was adapted for the coke addition to the SCF. After testing the new advice-based control for several months, the production data confirm the predictions by thermodynamics: since the prediction was implemented as an advisor, the copper and magnetite content in SCF slag is significantly reduced and viscous slag is reported less often by operations.

Aug 21, 2024

By F Faraj, M Pal, M Haest, M Bradshaw, H Lang, K Hume

MineSense Technologies Ltd. is revolutionising grade control at mining operations by installing ShovelSense® sensors on buckets that measure the grade of every load before it is dumped in the truck. This allows the mine to exploit grade variations at a resolution that was not available before, reducing the amount of ore loss to the waste stream and removing waste from material destined for processing. These changes dramatically improve the profitability and sustainability of mining operations. ShovelSense relies on X-ray fluorescence analysis of the rocks as they flow in the bucket and is integrated with fleet management to direct the trucks to the right destination. Lab simulations of ShovelSense measurements on porphyry copper ores show correlations between predictions and lab measurements at 0.98 r-squared with a coefficient of variation of 10 per cent. Visualisation of copper grade predictions in three dimensions shows a reasonable match with the dig plan, but with local changes in the ore-waste contact due to more accurate contact identification, related to blast movement and other mining factors. Correct delineation of these contacts ensures ore trucks are not sent to the waste dump and waste trucks are diverted from the crusher, creating enormous value for the operation and the environment.

Mar 22, 2022

By J Heyes, G A. Maddocks, R J. Stewart, G D. Corder

Mining is an international business and vital contributor to national and global economies. It depends on the trust and confidence of investors and stakeholders for its financial and operational well-being (Committee for Mineral Reserves International Reporting Standards (CRIRSCO), 2016). The Social Licence to Operate (SLTO) is an increasingly multifaceted and multistakeholder risk that can impact investment decisions. Community challenges to broader political and economic decisions have given rise to protest delaying or stopping projects or closing mines and has led to loss of life (Ernst and Young, 2016). Some governments are now giving greater powers to stakeholders to make the final decision on approving mining and metals activities (EY, 2016). With billions of dollars in project investment at stake, ongoing engagement, collaboration and effective communication with stakeholders is crucial and mutually beneficial solutions are increasingly expected (EY, 2016). It is therefore essential that the industry communicates the risks (and opportunities) associated with investment effectively and transparently in order to earn the necessary level of trust with investors and stakeholders to underpin its activities (CRIRSCO, 2016). Despite this need, investor and stakeholder trust in the sector has eroded in recent years.CITATION:Maddocks, G A, Corder, G D, Heyes, J and Stewart, R J, 2016. The social licence to operate and drivers for change – resource reporting and mine material characterisation, in Proceedings Life-of-Mine 2016 Conference, pp 183&ndash;187 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By D van der Spuy, T Kewe, K Keet, N Moffatt, A P. Paine

The Blue Cube Mineral Quantifier Inline (MQi) instrument uses reflective light spectroscopy and advanced chemometrics to measure mineral or elemental grade in a slurry line. The instrument takes scans continuously and sends data to the DCS or PLC control system.Controlling the concentrate grades on a flotation circuit using low-frequency measurements can be difficult or impossible, especially on a circuit that has fast process dynamics. The ability to rapidly measure changes in grade makes it possible to continuously manipulate the flotation circuit operating parameters such as level, airflow and reagent addition set points to optimise plant performance throughout changing conditions.At Barrick’s Porgera mine in Papua New Guinea the flotation circuit feeds sulfide concentrate slurry to a pressure oxidation circuit. In order to maximise gold recovery in the flotation plant and increase performance in the pressure oxidation process, there is a stringent requirement to maintain a stable and optimum sulfur grade. The gold recovery is directly affected by the sulfur grade as most of the gold at Porgera is submicroscopic and associated with the sulfides (disseminated?pyrite).Porgera considered various points in the flotation circuit for installing Blue Cube analysers. This was part of a plant upgrade to improve process control. Due to budget constraints it was decided to initially only install one Blue Cube analyser on the final concentrate stream of the flotation circuit measuring sulfur, sulfides, gold and particle size. The accuracy of the calibration results were very good for all these properties. The sulfur measurement was used in an advanced control system to optimise and stabilise the grade. The paper presents comparisons between mineral grades determined using analytical laboratory analyses and the online Blue Cube data measurements, as well as benefits achieved by measuring grade online. An analysis of the plant data before and after installation of the Blue Cube and the advanced process control upgrade indicate that the flotation recovery increased by 1.98 per cent.CITATION:Kewe, T, Moffatt, N, Strobos, P, van der Spuy, D, Paine, A P and Keet, K, 2014. Evaluation of the Blue Cube MQi slurry analyser for application in an advanced control system for the optimisation of a gold sulfide flotation circuit, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 357–362 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By B T. Qin, C Zhu, Y W. Jia, Y Lu, F L. Li, Q L. Shi

Air leakage through rock fractures in coal mining is a major cause of coal spontaneous combustion. In order to overcome the deficiency of the existing fire control technology and prevent coal spontaneous combustion by isolating coal from oxygen, the article proposes a novel technology of inorganic solidified foam (ISF) with high expansion to fill fractures effectively. ISF consists of fly ash, cement, setting accelerator, redispersible polymer powder, water and aqueous foam. For preparing homogeneous and stable ISF, a preparation system with a pore type foam generator, a mixer device installed with a hollow shaft and helical blades, air compressor, slush pump and monitoring instruments was developed, and the working principles of key devices were elucidated. Based on a series of experiments on the different ratios of each component material and technological parameters of the preparation system, ISF with a foam expansion ratio of 8~10 and dry density of 250–400 kg/m3 was prepared. The relationship between elastic compressive strength, modulus of elasticity and density was summarised. Based on the injection experiment for fracture of loose coal pile with high temperature, the characteristics of sealing air leakage, compressive strength, thermal insulation, flow and cooling of ISF in the fresh state were investigated, indicating that ISF can effectively cut off the air leakage and cover the coal sample to reduce the temperature in the earlier stage, and ISF can remain stable and not crack. The ISF was applied to Luwa coalmine to seal small coal pillar pressure fractures and loose coal fractures in goaf. After press-casting the ISF in Luwa coalmine, the pressure-difference of inner-outer increased, meaning the effect of external conditions on the pressure-difference decreased, showing that it could plug the air leakage effectively.CITATION:Qin, B T, Shi, Q L, Lu, Y, Zhu, C, Li, F L and Jia, Y W, 2015. The novel technology of inorganic solidified foam with high expansion for preventing coal spontaneous combustion, in Proceedings The Australian Mine Ventilation Conference, pp 121–126 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By G Bickert

Australia is currently developing and engineering a range of specialised processing options for rare earth (RE) (Lynas, 2011, Alkane, 2005), zirconia (Alkane, 2005), lithium (Galaxy Resources, 2008) and other special minerals and metals required in high-tech applications. The processing of lithium, zirconium and RE minerals is based on complex leaching processes which require extensive liquor clarification, solid liquid separation and solids washing. The filtration properties for those leach liquors, residues and precipitates are not well understood and differ drastically according to the process route applied. Thus, filtration test work is essential for equipment selection, sizing and design. Similar types of slurries are filtered in laterite nickel, TiO2 and other chemical oriented processes, while more experience is available here as those processes are applied widely for a number of decades. The increasing need for dry stacking of tailings requires advanced tailings filtration with properties differing drastically depending on tailings properties. More traditional mineral processes such as flotation commonly apply filtration. All of these and other cases require proper filtration test work particularly evaluation of vacuum versus pressure filtration and the need for cake pressing and/or air blowing for filter presses. Bench scale test work and/or pilot plant operation is common to determine filtration rates, achievable cake moisture and wash efficiencies and sometimes filtrate clarity. While those values are important, there is much more valid information to be obtained by filtration test work.This paper discusses the intricacy of filter selection and sizing based on driving forces (vacuum and pressure air, compression by mechanical means and slurry) and parameters (cake thickness, forces and times) and different processes utilised in common filtration equipment. It will discuss the in’s and out’s of filtration test work design, planning, and in particular data gathering, processing, reporting, evaluation and filter sizing from recent examples of bench and pilot scale filtration test work for above applications together with methods for predicting filtration performance for example where test work is lacking. One focus will be the realistic extrapolation of test work results towards different parameters utilised in full scale equipment and plants. The conclusion of the paper will contain checklist for filtration test work.

Aug 8, 2011

By D Espinoza, I Rees, J Pocoe, P Collier

P Collier, I Rees, J Pocoe and D Espinoza

Mar 22, 2022

By T Sua, B Wright

"BHP Billiton West Australian Iron Ore (WAIO) conducts an extensive geometallurgy program for its iron ore deposits in the Pilbara with the focus on determining the lump yield (the mass percentage of &gt;6.3 mm rocks) and the lump and fines grade for iron ore products. The geometallurgy program provides accurate information to design engineers and technical marketing teams on the performance of different iron ore mineralogies for future deposits. Additionally geometallurgy results are being used to guide short-term production planning with their introduction into short-term geology models and grade control models. The data that underpins this knowledge is from dedicated geometallurgical programs, drilled using PQ (~83 mm) holes. These holes are crushed by intervals that are based on geological definition which provides an indicative lump yield and lump and fines grade. The lump is then subjected to standard dropping and tumbling test stages to produce a simulated lump and fines product. In the past, quality assurance, quality control holes were drilled using HQ (~64 mm) holes for geochemistry purposes. These holes were crushed to provide an indicative lump yield and lump and fines grade and then 100 per cent is sent for assay (with no dropping and tumbling). Utilising data from HQ holes can significantly increase the indicative geometallurgical data available. This paper compares the geometallurgical results from both PQ and HQ holes from a range of bedded iron deposits (Brockman and Marra Mamba). The PQ and HQ data are compared by orebody, stratigraphy and depth to exclude factors that are expected to influence geometallurgical results.CITATION:Wright, B, Sua, T, Robertson, B and Van Dijken, B, 2016. Comparison of Diamond Drill Size on Iron Ore Geometallurgical Results, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 161–166 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By R Hargreaves, T Elkington, W J. Shaw, G W. Booth

Every day, around the world, thousands of tons of ore are loaded onto ships completing the miningproduction process and starting a multimillion-dollar economic transactions process. These transactions are based on the supply of tons of a commodity with certain specifications of assays of the main element (or physical properties) and concentration of contaminants, which are finally verified and evaluated by buyers, and also are considered ‘as true’ during Reconciliation process. On Sample Stations, this ‘true’ is based on a few kilograms of sample, often representing thousands of tons, that are sent to laboratories for further sample preparation and chemical analysis, where finally assay information is obtained from a few grams of pulverised sample, and are used for further production, planning, operational and financial-marketing decisions. Different International Standards (depending on the commodity) are used to establish the methodology to be followed, to set-up and obtain samples from the Sample Stations, and the specifications are visually inspected to give an estimation on the performance of the sampling point. This paper seeks to highlight with examples, the importance of the implementation of a continuously monitored Quality Program (QAQC and QM) on Sample Stations, focused on the parameters that directly affect the quality and representativeness of the samples. By this implementation, a proactive approach and better-informed decisions can be taken for mining companies to: a) quantify/improve production and reconciliation results, and b) to supply the right specifications of shipped ore, increasing the value of the Resources. Finally, laboratory results are normally used as an indication of the quality of the information applied for the economic transaction, but it should be considered, clarified and highlighted that the laboratory will only process and analyse a sample obtained from a Sample Station, and potential problems on bias or precision may occur in stages prior to the laboratory reception. Hence the importance of the implementation of a quality assurance program that protects multi-million dollar decisions.

Mar 22, 2022