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By Mario Alejandro Bendezú

Este trabajo tiene como objetivo mostrar la importancia de la minería junior en la creación de nuevas minas, así como en el mercado de valores. Este documento tocará los retos por los que está atravesando el sector junior, y analizará las acciones, factores, estrategias y documentos públicos provistos por ciertas mineras junior que lograron llegar a su objetivo. En el primer capítulo de esta tesis se abarcará los conceptos esenciales para poder conocer la minería junior en el cual se precisarán definiciones tale como la de éxito, valor y objetivos que buscan alcanzar este tipo de empresas. En el segundo capítulo se analizará cómo la minería junior ha contribuido en la exploración minera a nivel global. De la misma manera, se identificarán los principales desafíos que están impidiendo que las mineras junior continúen con sus operaciones exploratorias normalmente. El tercer capítulo tiene como finalidad realizar el estudio y análisis de aquellas mineras que llegaron al éxito, para realizar esto se ha recopilado toda la información relevante que puede haber contribuido a que la minera junior analizada haya cumplido su objetivo. Por último, se presentaran una serie de ratios, estrategias y variables extraídos del análisis de las mineras junior exitosas para poder identificar a las actuales junior que están encaminadas al éxito.

Sep 21, 2015

By Juan Silbino Marceliano Rojas

Volcan Compañía Minera S.A.A. es una empresa minera peruana que inicia sus operaciones en el año 1943. A lo largo de sus 71 años ha logrado posicionarse como la primera productora de plata, plomo y la segunda en zinc a nivel nacional. Durante este periodo la compañía se ha expandido y ha alcanzado excelentes resultados de productividad. Sin embargo, estos resultados no han sido acompañados de indicadores de seguridad favorables. En los últimos 12 años (2000-2011) se han presentado 88 fatalidades, 960 accidentes incapacitantes y 1400 accidentes leves. En el 2012, la dirección de la organización decide realizar un cambio trascendental en la gestión de seguridad, estableciendo como primer objetivo estratégico de la compañía la implementación de una cultura de seguridad de clase mundial para minimizar la frecuencia y la severidad de los accidentes de trabajo. Partiendo de este objetivo en el año 2012 realizó un diagnóstico a nivel corporativo que nos ubicó en una fase de dependencia en relación a la curva de cambio de cultura, tomando como base el concepto de Bradley e identificó la necesidad de efectuar un cambio en dos frentes: Sistema de Gestión SSO y Líderes. Diseñamos una "Estructura Organizacional" en los tres niveles de operaciones, lo que involucró a los líderes y evidenció así el "Liderazgo Visible". El sistema se basó en cuatro pilares fundamentales y aplicó las siguientes herramientas: gestión de riesgos, condiciones, conocimiento y comportamiento. Dentro del pilar condiciones, priorizamos doce riesgos críticos para contener los accidentes mortales e incapacitantes. Los Líderes fueron entrenados en la herramienta de gestión y en los cuatro pilares del sistema. De esta manera se logró el impacto directo en la supervisión y los trabajadores, así como desarrollar las competencias de comunicación, motivación, retroalimentación, confianza y compromiso. El modelo está evolucionando la cultura de seguridad hacia una fase de interdependencia. Hemos reducido los índices de frecuencia en un 55%, severidad en un 92% y accidentabilidad en 96%, sin embargo nuestro logro más importante es la contención de los accidentes mortales a la fecha.

Sep 21, 2015

By Luis Wilson Arzapalo

El tema refiere a las acciones que llevara a cabo el equipo de operaciones, una vez terminado el "Comisionamiento" donde la Planta ha alcanzado el estado "Listo para Arrancar". En el periodo de puesta en marcha de una planta de proceso, se encuentra una serie de dificultades de índole operativo; saltan a luz las propiedades físicas y químicas del mineral no detectados durante las investigaciones metalúrgicas previas, se hacen presente los defectos de diseño de los equipos los cuales a su vez pueden estar sub o sobredimensionados y otras manifestaciones no esperadas. En tal virtud el conocimiento de los metalurgistas experimentados en este tema, las continuas prácticas de liderazgo participativo y la capacidad de decisión, deben hacer que los motores y equipos reciban la alimentación planeada y entreguen el producto esperado para garantizar el equilibrio del sistema.

Sep 21, 2015

By Francisco Macías

Los drenajes ácidos de mina de la Faja Pirítica Ibérica presentan una elevada acidez y altas concentraciones metálicas. En la mina abandonada de Monte Romero se ha testado un sistema de tratamiento pasivo multi-pasos a escala piloto, para tratar una descarga ácida con un pH de 3, 380 mg/L de Zn, 275 mg/L de Fe, 100 mg/L de Al, 15 mg/L de Mn, 5 mg/L de Cu y 0.1-1 mg/L de As, Pb, Cd, Co y Ni. El sistema consta de un primer pretratamiento denominado NFOL, donde se recrean a gran escala los procesos de atenuación natural observados en las terrazas de Fe de estos ambientes. Posteriormente el agua fluye a través del tratamiento Sustrato Alcalino Disperso (DAS), el cual está formado en primer lugar por dos tanques de 3 m3 rellenos con la mezcla reactiva DAS-caliza (80% virutas de madera y 20% de arena caliza), y conectados en serie con 4 piscinas decantadoras de 6 m3. Finalmente el agua fluye a través de un último tanque de 1 m3 de capacidad relleno con la mezcla reactiva DAS-magnésica (80% virutas de madera y 20% de MgO tamaño polvo). En el pretratamiento NFOL se produce la retención de aproximadamente el 35% del Fe, así como un 75% del contenido en As. En la parte basada en la disolución de la caliza queda retenido el resto de Fe y As, y el 100% de Al, Cu y Pb. Finalmente en el DAS-magnésico la totalidad de Zn, Mn, Cd, Co y Ni son retenidos. Basándonos en esta tecnología y mediante financiación de la Unión Europea a través del proyecto LIFE-ETAD (LIFE12 ENV/ES/000250) se está desarrollando un ambicioso proyecto para la implementación a escala real de un tratamiento pasivo para aguas ácidas con altas concentraciones metálicas, en colaboración con la empresa Sacyr Construcción y la Agencia de Medioambiente y Agua de la Junta de Andalucía.

Sep 21, 2015

By Albert H. Herrera

La microcuenca Tres Ríos, está ubicada en el distrito de Cajamarca, Región Cajamarca y al NW de la ciudad de Cajamarca, abarcando el centro poblado de Chámis, Corizorgona, Collpayoj y parte de Ronquillo, con un área aproximada de 39.653055km2, a una elevación de 2800 a 3800msnm. Ubicada a 10 km aproximadamente de la ciudad de Cajamarca. Las Formaciones existentes en la microcuenca Tres Ríos son del Ki-desde el Aptiano (Grupo Goyllarisquizaga) con la Fm. Farrat hasta Ks-Turoniano con la Fm. Cajamarca. (Boletín 31.Serie a.-Geología del Perú-INGEMMET). Siendo las primeras Formaciones las más importantes a tomar en cuenta para la construcción reservorios artesanales para el almacenamiento del agua.

Sep 21, 2015

By J. Ipinza

Más del 70% de las reservas de cobre se encuentran contenidas en yacimientos de calcopirita. La lixiviación bacteriana de la calcopirita es cinéticamente lenta (ciclos de 300 a 320 días) y con extracción de cobre bajo 40%. El pre-tratamiento de minerales de calcopirita consiste en su humectación con agua y adición óptima de cloruro de sodio y ácido sulfúrico concentrado, seguido de un tiempo de reposo conforme a las características propias del mineral, lo que permite una extracción del cobre sobre 70% en alrededor de 120 días. El pre-tratamiento que antecede a la lixiviación en la pila es la etapa clave para el éxito de esta nueva técnica, que ha sido aplicada con éxito a nivel semi-industrial para el beneficio de sulfuros de cobre secundarios. Experimentos de voltametría cíclica complementados con análisis de DRX y SEM, permiten la identificación de los compuestos formados durante el pre-tratamiento, en ausencia y presencia de concentraciones variables de cloruro de sodio. Los resultados indican que los productos de reacción están asociados a calcosina, covelina y polisulfuros de cobre. El cloruro de sodio promueve la formación de sulfato de sodio disminuyendo la ocurrencia de azufre elemental, condición favorecida a temperaturas sobre 50 °C.

Sep 21, 2015

By Lucy Villena

El presente trabajo se detalla los resultados más importantes de los estudios realizados de la mineralogía (mena y ganga) y microtermometría con el objetivo de caracterizar los flujos mineralizantes y la dirección de la migración de los fluidos mediante los paleoisotermas de la veta 1. La veta polimetálica es comprendida Pb-Zn-Ag compuestas por rocas volcánicas (andesita a basáltica), cuyo control estructural principal está dado por fallas tensionales de dirección NE-SO, causadas por el movimiento sinestral de fallas Chonta y Huachocolpa- Huancavelica. La composición de las menas reconocidas en la veta 1 corresponde a esfalerita, galena, tetraedrita, bournonita, acantita-argentita y calcopirita, en una ganga conformada por cuarzo, calcita, barita, adularia y yeso. En las muestras de la veta estudiada, los estudios microtermométricos fueron realizados en los cristales de baritina, calcita, cuarzo y esfalerita asociada a la mineralización. Se observan inclusiones fluidas bifásicas acuosas (LH2O + v H2O) las cuales poseen al menos tres eventos mineralizantes según temperaturas de homogeneización y salinidad % equivalente en peso, los fluidos mineralizantes son moderadamente salinos, sugeriendo un ambiente de tipo epitermal.

Sep 21, 2015

By Jhony Mamani

El presente trabajo muestra dos casos de recuperación de recursos en rampas y taludes finales de un tajo abierto: el primer caso está referido a la recuperación de mineral en la rampa principal del tajo Chaquicocha, y el segundo caso sobre la recuperación de mineral en taludes de los tajos El Tapado y La Quinua. Durante la etapa del diseño y la planificación del Tajo Chaquicocha se identificaron zonas con potencial mineral por debajo del límite económico que podían ser aprovechados, una de estas zonas fue la rampa principal del Tajo Chaquicocha que fue evaluada considerando las nuevas condiciones topográficas del tajo final, para lograr recuperar estos recursos se presentó una alternativa que considero la explotación con equipo mayor, logrando obtener después del desarrollo de la ingeniería 77 Konz. de Oro. El segundo caso es la recuperación de taludes de los tajos El Tapado y La Quinua, específicamente las bermas de seguridad o "Catch Bench" (CB), la alternativa para recuperar estas zonas se desarrolló durante la etapa de cierre de los tajos El Tapado (ET) y La Quinua (LQ) que fueron considerados como depósito de desmonte, aprovechando la altura de la descarga de este nuevo depósito se logró recuperar los "Catch Bench" obteniendo 11 Konz de Au.

Sep 21, 2015

By M Hourn, D Turner, P Voigt, D Mallah

The GPM Gold Project is located in Armenia, and consists of an open cut mine at Zod, near the Azerbaijan border, and a CIL processing plant at Ararat near the Turkish border. Mining at Zod commenced in 1976, and focused on near surface oxide ores, which overlay deeper refractory sulphides. Historical mining has now almost depleted the oxide ores, and the sulphide content of ore delivered to the processing plant at Ararat is increasing. Gold and silver recoveries through the Ararat plant were declining steadily.GeoProMining, the owners of the project, have expanded the Ararat facility to deal with the increasing sulphide content in the ore. In 2014, GeoProMining refurbished an existing concentrator on site to recover a sulphide concentrate from the ore, and have constructed an Albion ProcessTM plant to oxidize the refractory concentrate. Glencore Technology (GT) provided the Albion ProcessTM plant as a technology package.In July 2014, the progress of the GPM Gold Project Albion ProcessTM Plant was reported (Hourn, Voigt and Turner, 2014). At the time of writing, the construction of the plant was nearly complete. This paper presents an update of project progress, covering commissioning and ramp up of the GPM Gold Project.The commissioning phase occurred over June to August 2014, which included an M3,000 IsaMillTM fine grinding plant, a 6 tph limestone milling plant, a 60 tpd vacuum pressure swing adsorption oxygen plant, a 10 m residue thickener and a 12 tph Albion ProcessTM oxidative leach plant. Since commissioning was completed, ramp up occurred over the following three months with downstream gold recoveries from cyanide leaching reaching over 98%.CITATION:Voigt, P, Hourn, M, Mallah, D and Turner, D, 2015. Commissioning and ramp-up of the Albion Process at the GPM Gold Project, in Proceedings MetPlant 2015, pp 207–219 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By J Mercuri, S Dunford, P Rothman, E Bartsch, J Snyder, D Newton, R Maron, D Cirulis

The purpose of a mineral comminution circuit with a ball mill running in closed-loop with a hydrocyclone classification cluster is to feed the downstream process with the target particle size. Maintaining the optimal particle size in the flotation feed can significantly improve plant cash flow. In particular, reducing the amount of coarse material is often a major challenge. Existing instrumentation to provide particle size measurement is considered standard equipment in most modern concentrator plants. However, availability is often very low, mainly owing to high maintenance requirements of the analyser and associated sampling system.CiDRA Minerals Processing has developed two novel and robust technologies that address this challenge by providing high reliability and very low maintenance systems for on-line measurement of coarse material in the overflow of individual hydrocyclones. The first system is non-invasive and measures pebbles and rocks greater than 6 mm. This paper focuses on the second system, which is a ruggedized wetted sensor design with no moving parts and provides a real-time trend of the desired target grind size parameter, such as percentage above 150 micron.Both systems have simple robust designs and measure in the primary overflow stream of the individual hydrocyclone. Individual hydrocyclone measurement enables identification of poor performing hydrocyclones in addition to providing a representative measurement of the whole hydrocyclone cluster. The systems do not require sampling and associated sample transfer piping circuits that are prone to plugging, thus avoiding high maintenance requirements.The wetted sensor will be described in detail along with its implementation in a robust control scheme in a major copper concentrator in North America. Plant data shows very high availability, achieved with very low maintenance, has enabled improved process control, thereby maintaining throughput and ball mill target power while reducing grind size.CITATION:Cirulis, D, Dunford, S, Snyder, J, Bartsch, E, Rothman, P, Maron, R, Newton, D, O’Keefe, C and Mercuri, J, 2015. Process optimisation using real-time tracking of coarse material in individual cyclone overflow streams, in Proceedings MetPlant 2015, pp 93–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By K Cameron, S Strohmayr, J Wallace

In 2012, a single module heavy medium cyclone plant (HMP) was installed at the Glencore Zinc’s (then Xstrata Zinc) McArthur River lead zinc mine. The HMP formed the first part of the MRM Phase 3 Project to increase run of mine (ROM) capacity from 2.4 to 5.5 Mt/a.The purpose of the HMP is to remove liberated gangue from the crusher product at minimal loss of valuable mineral. The McArthur ores are very finely disseminated requiring a fine primary grind size prior to rougher flotation. Rejecting waste prior to grinding therefore offers significant power and grinding media savings. The plant was designed to treat only those ores with a reasonable upgrade ratio at the target zinc recovery across the HMP of 95%.On this basis, a 1.8 Mt/a single module plant was built based on 250 t/h feed rate and 82% availability. In contrast to existing base metal heavy medium plants in Australia, the MRM Flow sheet utilised the principles in modern coal heavy medium cyclone plant design. Since commissioning, the plant feed rate has been significantly increased and is now normally operated up to 540 t/h (dry basis).Although this throughput increase is partially due to debottlenecking work, it is also attributable to the conservative design parameters for base metal heavy medium cyclone circuits in comparison to those used in equivalent coal circuits.This paper discusses Flow sheet design and compares traditional base metal design parameters with those achieved at MRM and those of modern coal plants. It provides information on plant capital and operating costs and the net savings realised by its installation. In addition to power and grinding cost savings, the paper also highlights the savings in water through rejection of near dry waste and reduction of tailings pumped to the storage dam.CITATION:Wallace, J, Strohmayr, S and Cameron, K, 2015. McArthur River Mine heavy medium plant – the benefits of applying modern coal plant design principles to base metal heavy medium separation, in Proceedings MetPlant 2015, pp 311–323 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By A Rantala, K Aberkrom, O Haavisto, P Blanz

More complex ore bodies with lowering grades increase the challenges of maintaining high throughput, energy efficiency and required particle size for optimal downstream processing in grinding circuits. Continuous and often rapidly changing characteristics of the mill feed requires constant focus to operate the circuit at optimal level. Modern process instruments, on-line analyzers, monitoring and process control systems provide attractive and managed options to increase the circuits’ capability to respond to the challenge, often in phases and in rather short time period. Furthermore, well instrumented and performing base level automation in the grinding circuit enables advanced process control (APC) strategies that utilize measurements from the whole circuit to stabilize and optimize production. In this paper alternatives for incorporating process measurements and controls to typical grinding circuits are proposed. The expected benefits to throughput, availability, energy efficiency and particle size stability are described in recent case examples.CITATION:Rantala, A, Blanz, P, Aberkrom, K and Haavisto, O, 2015. Increasing grinding circuit robustness with advanced process control, in Proceedings MetPlant 2015, pp 129–141 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By G J. Delemontex, N J. Grigg

Pre-concentration of precious metal and base metal ore types is becoming more relevant with the discovery, development and operation of many lower grade deposits around the world. The fluctuations in metal prices expose many mines to risks especially dealing with low and variable ore grades.Pre-concentration, the process of concentrating the valuable metal into a smaller mass yield, effectively results in the introduction of higher feed grades to milling circuits. Gangue Rejection, the removal of lower S.G. waste rock from the circuit not only results in higher downstream grades but also potentially removes harder, non-valuable mineral, providing significant power savings within the circuit. The pre-concentration or ‘gangue rejection’ process offers a number of benefits when considering the treatment of marginal ore deposits, especially if it can be performed at a coarse crush size; these benefits include a reduction of the operating costs and the feed of more metal units to the mill.Gekko Systems has effectively utilized the Inline Pressure Jig (IPJ) to pre-concentrate the valuable metal, achieving high primary recoveries into a range of mass yields resulting in upgrade ratios between 2 and 10 times.This paper explores the benefits of pre-concentrating ‘marginal’ ore deposits prior to the milling circuit; the selective rejection of ore types that may affect either the recovery or comminution process, and also looks into the potential to effectively reduce the ‘cut-off’ grade when considering the mine planning process. Case studies of projects using the IPJ to pre-concentrate and reject gangue are also included.Pre-concentration and gangue rejection provide the potential to develop marginal ore deposits, thus providing higher grades, less gangue and more metal at a lower operating cost to producers.CITATION:Grigg, N J and Delemontex, G J, 2015. The pre-concentration of precious and base metal deposits using the Inline Pressure Jig – higher feed grades and more metal, in Proceedings MetPlant 2015, pp 296–310 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By A Hoyle, P Walker, D Bennett

The Phu Kham copper-gold operation located in Laos People’s Democratic Republic (PDR) is owned and operated by Phu Bia Mining Limited. PanAust Limited, based in Brisbane Australia, holds a 90 per cent interest in Phu Bia Mining Limited, with the remaining 10 per cent held by the Government of Laos PDR.The 12Mt/y copper-gold concentrator at Phu Kham commenced production in April 2008. Flotation copper and gold recovery from commissioning was consistently poor, due to the high levels of pyrite and problematic secondary and oxide copper species and non-sulfide gangue.The low recoveries of copper and gold from Phu Kham were recognised during the feasibility study design phase. A bulk sulfide flotation regime in roughing produced high recoveries, however a large capacity cleaning circuit was required and there was risk of not meeting saleable concentrate grade specifications. The installed design offered a capital efficient compromise to ensure that a concentrate grade of 24% copper could be achieved at acceptable recoveries.Incremental improvements in copper recovery were achieved by 2011 through conversion of conditioning cells to flotation cells in both roughing and first cleaning and increased cleaner capacity through the installation of a Jameson cell. In 2012 the Phu Kham Upgrade Project was commissioned to increase mill throughput, along with additional rougher and cleaner capacity to increase residence times at the nominal 16 Mt/y throughput. The marginal reduction in primary grind size due to the additional ball milling power also provided a small recovery improvement.This paper presents the development, design, implementation, and performance of the Increased Recovery Project commissioned in April 2013 which targeted the major causes of copper loss from the circuit. Based on fundamental and detailed test work and mineralogical analysis of concentrator streams, an optimised design was developed which has increased copper and gold recoveries by over 5% and 10% respectively. The Increased Recovery Project has positioned the concentrator to process high pyrite ores that were previously considered untreatable, and opened further opportunities for maximising flotation recovery by de-bottlenecking plant regrind and cleaning capacity.CITATION:Hoyle, A, Bennett, D and Walker, P, 2015. The increased recovery project at the Phu Kham copper-gold operation, Laos PDR, in Proceedings MetPlant 2015, pp 246–265 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By V Cullinan, D Buchanan

The Brunswick plant is located in Costerfield, approximately 40km east of Bendigo in central Victoria. Crushing, grinding, gravity gold concentration and flotation methods are used to produce a saleable gold concentrate and an antimony-gold flotation concentrate. This paper discusses the improvements made within the processing plant which have resulted in a 99% increase in throughput over nameplate capacity of 6 250 average tonnes per month to 12 445 average tonnes per month and increases of 12% gold (from 2007 average of 78% to 2014 average of 90%) and 16% antimony recovery (from 2007 average of 79% to 2015 average of 95%). This combined effort has resulted in an increase of equivalent gold ounces (AuEq oz) produced from 2010-2014 of 15 872 to 82 574 – a 66 702 increase.AuEq oz= Au oz +Sb t × Sb (US$/t)Au (US$/oz)CITATION:Buchanan, D and Cullinan, V, 2015. Improvements in bi-metal production at the Brunswick Plant, Costerfield, in Proceedings MetPlant 2015, pp 267–272 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By G J. Lyman, F S. Bourgeois

As the prices of metals slide, financial control of mineral processing operations becomes more and more important. Control of a mineral processing operation implies measurement of grades, recoveries and losses, with every effort being made to recover more product from the same feed. Shareholders become more concerned with the transparency of the operations and the corporate governance.There is only one way to achieve this and this is by sampling and making good use of the results of that sampling. Sampling systems that provide only 'rough' figures are not good enough. Similarly, a competitive position in the marketplace demands close control of product quality. Maximisation of product output demands that the product just meet the specification so that product yield is maximised. Decisions based on precise sampling results carry less risk that those based on imprecise results.This paper reports some recent advances in sampling theory that permit full quantification of sampling distributions, not just the sampling variance as has been possible in the past. These advances can be used together with simulation methods to tie down sampling precisions and develop calculations that quantify decision making risk when using the sampling results. A number of examples illustrate the use of the new advances and a final example indicates the development of risk analysis curves in the coupling of sampling precision to sale of a commodity.CITATION:Lyman, G J and Bourgeois, F S, 2015. Sampling, corporate governance and risk analysis, in Proceedings MetPlant 2015, pp 27–34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By H Kurth

Geoscan is used for multi-elemental analysis of conveyed bulk materials in real time. It has been used for coal analysis since the 1990s, in the cement industry, and since 2003 for measuring mineral ore quality. Geoscan-M has proven performance and demonstrated paybacks of weeks or months, in iron ore, manganese, copper, zinc-lead and phosphate industries. Geoscan-M measures continuously through the full bed depth and is unaffected by belt speed, particle size, layering and dust levels. Increments of two minutes (typically one to five minutes) are accurately measured and provide the plant operators with tonnage weighted results of each element within seconds.A Geoscan installed after crushing is able to measure quality shortly after mining. The analysis results can be used to divert the increments based on composition, such as diverting waste for disposal and diverting marginal material to a stockpile for processing at a later date. The bulk sorting process allows different qualities to be placed into relevant stockpiles for subsequent blending. Material meeting product DSO (Direct Shipping Ore) quality can bypass a beneficiation circuit to prevent unnecessary treatment costs. An analyser in a blending application enables proportioning of different quality feed materials from multiple stockpiles to achieve a desired compositional consistency for process feed. The parameter used for decisions may be; a) primary metal content, e.g. Cu, Fe, P, etc. b) deleterious component content, e.g. Mg as an indicator of talc content, c) process parameter content, or a combination of these. Process parameter content may be the elemental ratio between critical components, e.g. Cu:S ratio, Fe:Si ratio, basicity, Lime Saturation Factor, etc. or the content of an “indicator” element, e.g. Si as an indicator of material hardness or grindability.Measurement of the composition in real time enables prompt feedback to the mining operators and also feed forward to the process operators. Compositional variability can be critical in the process and advance warning enables appropriate reactions prior to processing. This may include modifying the feed rate, changing the feed blend (through additives), or modifying reagent dosing in anticipation of a change in feed quality. Benefits include, but are not limited to; reducing waste processing, improved feed grade stability, reducing energy, water and grinding media consumption, producing less tailings, increasing process efficiency, higher metal recovery, better plant utilisation, reducing plant downtime, better utilising mined material, all achieved using the same process plant throughput capacity.CITATION:Kurth, H, 2015. Optimising plant feed quality and process performance using Geoscan elemental analysis, in Proceedings MetPlant 2015, pp 373–380 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By A Giblett, K Afewu

This paper uses a case study to demonstrate best practices techniques for predicting the contribution of gravity concentration in a gold recovery process flowsheet. The case study was selected as an example of an ore with a marginal gravity gold content, which makes the value of a gravity circuit difficult to quantify. In this instance the value of leveraging a significant knowledgebase of operating gravity circuit performance to support the decision making process was demonstrated. This case study analysis serves as a useful demonstration of best practice methodologies supporting decisions to include or exclude gravity recovery in a gold recovery process flowsheet.CITATION:Giblett, A and Afewu, K, 2015. Do we need a gravity circuit or not? A case study in applying best practice, in Proceedings MetPlant 2015, pp 288–295 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By S E. Munro, P D. Munro

The commonly traded base metals concentrates of copper, lead, tin and zinc are sold by miners to custom smelters using contracts whose terms were generally established at the beginning of the 20th century or even earlier. Technical clauses in these concentrates for items such as payable metals and penalty elements do not reflect current realities of extractive metallurgical technologies and hygiene/environmental issues.It is an axiom that the miners and smelters have a symbiotic relationship. While the existing antique and arcane commercial arrangements serve the purpose of transferring money from the buyer to the seller, they are not likely to result in the industry achieving better overall technical and economic outcomes. By examining the cases for copper concentrates and zinc concentrates in particular, it will be shown that the practical application of these antiquated technical clauses does not drive the miners to produce the better quality concentrates that should be desired by the smelters. This is despite development of mineral beneficiation and hydrometallurgical technologies that would allow the miners to make better products.The adage that any extractive metallurgical problem in the smelter is cheaper to solve in the concentrator still generally holds.While nickel concentrates are only touched on lightly in this discussion because sales terms are more opaque than those for the other base metals, it is expected that the same conclusions will apply.CITATION:Munro, P D and Munro, S E, 2015. Base metals concentrate sales contracts – change Pavlov and the dog, in Proceedings MetPlant 2015, pp 46–60 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By M Bird, B Oats, M Sganzerla

Mining operations are continually aiming to reduce operating costs to improve plant profitability. One way in which the Cannington operation sought to achieve this was by increasing the wear life and reducing the energy consumption of their flotation mechanisms. This was made possible using Outotec’s FloatForce mechanism. The FloatForce mechanism has been developed by Outotec over a six year period involving both CFD modelling and rigorous site testing. FloatForce delivers improved air dispersion and cell agitation efficiency; as such it can be operated at lower rotor tip speeds when compared to Outotec’s previous mechanism.Cannington trialled three FloatForce mechanisms in a train of ten OK38 zinc roughers. The mechanisms’ rotational speed was reduced by 10% compared to the previously installed MultiMix mechanisms. The purpose of the trial was to quantify the energy saving and assess whether there was any reduction in plant metallurgical performance.The trial was successful with FloatForce delivering a 17% reduction in power, an improvement in wear and improved recovery. Analysis of pre and post-installation metallurgical accounting data showed the following:The FloatForce installation resulted in a recovery increase of zinc to zinc final concentrate of 0.4 – 4.0%*The FloatForce installation resulted in a recovery increase of lead to zinc final concentrate of 0.0 – 0.3%*There was no statistically significant change in silver recovery to zinc final concentrate that can be attributed to FloatForce**95% confidence interval (CI) using multiple linear regression models.The Cannington operation is now in the process of further optimizing its power consumption and wear savings by changing the remaining OK38 zinc and lead rougher float cells to FloatForce mechanisms.CITATION:Bird, M, Oats, B and Sganzerla, M, 2015. Improvements in flotation cell maintenance, power consumption and operation at South32 Cannington, in Proceedings MetPlant 2015, pp 230–245 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015