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By P Klaric, N Swart, S Barnes

The recent advances in digital imaging technology, specifically around photogrammetry, have facilitated precision measurement in the difficult conditions encountered in an underground development mining environment. With the recent downturn in the resources industry, many mining houses have begun to focus on cost reduction projects and driving efficiencies. The application of digital photogrammetry has allowed greater insight into the development mining cycle and supported a focus on areas where efficiencies and cost savings can be achieved. Data collation, via digital image capture, can be completed with minimal disruption to the development mining cycle with analyses taking a nominal time to process and interpret. The result can be a stark visual representation of the result of blasting and associated activities of the development mining cycle. Many millions of dollars of benefit can be derived from understanding the impact of each component of the development mining process, with some of the biggest savings associated with conformance to drill design and the minimisation of overbreak during blasting. This paper will explain the image capture process, analyses and instigated improvement opportunities that were undertaken at a number of mine sites to improve efficiencies and drive savings in their development mining processes.CITATION:Klaric, P, Swart, N and Barnes, S, 2017. Digital imaging provides valuable insights into underground development mining, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 129–134 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By T M. Brettell, D Sidea

The CSA Mine is located in Cobar, New South Wales and is operated by Glencore. Large scale underground production started from 1965, with zinc, lead, silver and copper extracted in the past. The current operations focus on copper, with a silver co-product.From 2014 to 2016, Cobar Management Pty Ltd (CMPL) undertook a major capital project to upgrade the primary ventilation system at the CSA Mine. This involved the development of ten raises using full-face raise boring from surface to a depth of 1450 m. The total length of the raises was approximately 2500 m. Geotechnical conditions were identified as a key project risk during the early planning stages of the project. Timely quantification of the geotechnical risks was required to minimise project delays and cost overruns. Geotechnical investigations were planned and conducted for each raise prior to pilot drilling and full-face back reaming.Nine of the ten raises had final wall camera and laser baseline surveys completed following full-face reaming. The surveys were conducted progressively, allowing ongoing back analysis and calibration of geotechnical evaluations as the project advanced.This paper presents the design and planning process of the raise bored excavations. It details the geotechnical investigation work undertaken to mitigate the geotechnical risks and the challenges and learnings from the project including the benefits of close collaboration between the parties involved.CITATION:Sidea, D and Brettell, T M, 2017. The CSA ventilation upgrade – geotechnical challenges and learnings, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 341–352 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By J Cronin, R Burgess-Limerick, T Horberry, L Steiner

"Automation offers the mining industry great potential for improvements in productivity and safety. However, the experience of introducing automation in other industries has been that the full potential of new technology is not always realised. Designers are surprised, for example, to find that automation does not eliminate human errors. Unwanted and unexpected consequences also arise if the introduction of automation fails to consider how people will adapt to the new technology. A focus on the technical aspects of automation is necessary but not sufficient for success. The potential for improvements in productivity and safety promised by automation will only be achieved if the joint cognitive system that emerges from the combination of humans and automation is designed to perform the functions required for system success. This case study describes the human factors issues associated with the introduction of automation generally, and describes a case study of the successful implementation of loader automation at Northparkes mine.Information obtained through a site visit and interviews with operators, safety staff and the project manager revealed the following strategies for successful design and implementation of the automation system: involve the people who will be impacted encourage constant communication between operators and designers provide operators with essential information avoid providing non-essential information provide the operators with flexibility empower operators to take action take advantage of the new possibilities automation provides.CITATION:Burgess-Limerick, R, Horberry, T, Steiner, L and Cronin, J, 2017. Mining automation human-systems integration – CMOC-Northparkes case study, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 93–98 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 16, 2017

By J Graaf, R A. Murrell

Gold Fields Australia is constructing two major ventilation shafts at the Wallaby gold mine in Western Australia. The new ventilation shafts are required to facilitate the long term ventilation strategy for the mine, thereby allowing continued extraction of ore beyond 1000 m below the surface. The construction work has involved all of the challenges that shaft construction can throw up, including challenging geotechnical conditions, unexpected high water inflows and major circulation loss during pilot hole drilling for raise boring. An extensive geotechnical and hydrological investigation program was undertaken prior to awarding the shaft construction contracts. While most of the risks were identified, several proved to be much more challenging than expected. The shaft construction methods included conventional sinking into the fresh rock profile in each shaft, followed by raise bore pilot hole drilling and reaming. A headframe was constructed for the first shaft, which was sunk to 92 m with a stage suspended in the shaft to facilitate the concrete lining and provide rope guides for the kibble winding. Drawing from experience when sinking the first shaft, additional ground pre-conditioning was implemented for the second shaft, which was pre-supported with continuous piles to 28 m followed by sinking to 50 m using a crane instead of winders and a headframe. Following the conventional sinking through the weathered zone in each shaft, the shafts were completed using a raise bore. The first shaft utilised a riser pipe and rotary vertical drilling system (RVDS) with the second shaft having utilised a dual rotary rig for pilot hole drilling. This paper reviews the site investigations undertaken, construction methodologies applied, the results achieved and the lessons learnt.CITATION:Murrell, R A and Graaf, J, 2017. Shaft construction at the Gold Fields Wallaby mine, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 321–334 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By D Kilkenny

Underground contractors in the mining industry must be prepared to take a position at the forefront of innovation of equipment and work methods in order to maintain a competitive advantage over in-house operations and remain relevant. Innovative concepts such as split-feed development jumbos, high capacity trucks and loader guidance systems were implemented by contractors to stay ahead of ‘the pack’. All of these are now common across the industry.The demands of regular participation in competitive tendering coupled with aggressive fleet depreciation, means contractors tend to have more communication and opportunities to work with equipment suppliers than mine owners. Therefore, they are more likely to influence equipment design and product directions. They also have a unique opportunity to assist in trialling new concepts and technologies across a wide variety of operating conditions rather than being restricted to one mine.In addition, as a ‘guest’ on a mine site, mining contractors do not have the luxury of creating the environment for their preferred systems, rather they must have the capacity to adapt their technology to suit the offered environment at a particular mine. This leads to a pursuit of adaptive technologies that can be implemented selectively and seamlessly without excessive disturbance rather than ‘all-of-mine’ systems. These incremental innovations then become available for use across the mining industry where they can add value as ‘bolt-on systems’ to existing operations.Mining contractors, therefore, act as the bellwether for industry practices and equipment. However, in order to maintain their position they must engage industry stakeholders to deliver practical, innovative and cost-effective technologies that add value and result in an improved bottom line for all. This paper uses case study material to illustrate how the Byrnecut Group has approached innovation and how the theory of Disruptive Technology applies to underground mining innovation.CITATION:Kilkenny, D, 2017. Innovation in mining – a contractor’s role, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 59–68 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By A D. Campbell

Conversion of Mineral Resources to Ore Reserves requires a multidisciplinary approach and application of a number of Modifying Factors. The Modifying Factors for mining, particularly dilution and recovery in a caving mine are complex and can be difficult to determine. Cave flow modelling software is widely used for mine planning, scheduling and forecasting metal production. However, the conversion of Mineral Resources to Ore Reserves remains a difficult and subjective process and a consistent approach to convert Mineral Resources to Ore Reserves as part of the cave flow modelling process is not published in the literature. This is due to the difficulty in estimating the Ore Reserve that remains as cave stocks at a particular point in the mine schedule, the recovered tonnage and grade of the diluting material at various stages in the mine life, as well as the Mineral Resource classification of both the recovered and diluting material that forms the Ore Reserve. The key principle of this paper is the tracking of the Mineral Resource classification in the flow model used to estimate the Ore Reserves. This is critical to defining the Ore Reserve as Proved or Probable and enabling transparency in the reporting process. An approach for dealing with mineralised external dilution in the Ore Reserve estimation process is also provided.This paper outlines the approach to convert Mineral Resources into Ore Reserves developed at the Ernest Henry mine sublevel cave (EHM SLC). The same method could be used in any cave mine and applied at any stage of the mine life. The process replaces broad-brush assumptions for the mining Modifying Factors, such as dilution and recovery, as these are determined numerically as part of the model computation. This paper explains the Ore Reserve estimation method with a worked example to enable the reader to adopt the process at any caving mine. Mineral Resource classification within the block model is embedded in the cave flow model and the flow model results used to attribute tonnes, grade and the mixed proportions of the Mineral Resource classification for material extracted from each drawpoint. This information is then used to convert planned mine production into the appropriate Ore Reserve classification. Since the flow model simulation follows the mine schedule, it can be used to predict depletion and cave stocks at any stage of the mine life, and can calculate a residual block model at the end of the mine life. The accuracy of the flow model is checked by validating the forecast ore grade and metal tonne with reconciliation data from the concentrator which is also used to calibrate the flow model.CITATION:Campbell, A D, 2017. A simple and accurate method for Ore Reserve estimation and Mineral Resource depletion in caving mines, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 253–260 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By G Noonan, S Thomas, M Limbert

Stuck drill rods (often referred to as bogged rods) in production ‘upholes’ are a common problem in the underground mining industry. Bogged and broken off drill rods have the potential to fall out of the hole without warning, posing a serious hazard to personnel and equipment below.Current industry practice to alleviate this hazard can be to either grout the hole in order to lock the drill rods in place, or to ‘plate over’ the hole with a rock bolt. Each of these operations seriously delays mine production as both require demobilisation of the production drill and mobilisation of alternative personnel and equipment to address the hazard. Both methods have been assessed for safety and efficiency and were found to be expensive, time consuming and in the case of plating over, ineffective.To address the safety and efficiency short-comings of the traditional practices, the long hole plug (LHP) has been developed to safely secure the lost rods in the hole. The LHP when struck by falling drill rods behaves similar to an expansion shell anchor transferring the axial forces from the falling drill rods horizontally into the rock mass. It is installed using standard production drills allowing work to safely continue with little interruption.Extensive testing has been carried out on the LHP in the laboratory and underground at the Rosebery mine on the west coast of Tasmania, Australia. Testing has included static pull testing, full scale drop testing and underground trials.The outcome of this work has proven the LHPs ability to add safety, volume and cost benefits to the Rosebery underground operation and it is currently in use at that site. It enables proven elimination of a common workplace hazard immediately, thus eliminating delay on the mine’s production cycle.CITATION:Thomas, S, Noonan, G and Limbert, M, 2017. Long hole plug – addressing the hazard of bogged rods in ‘upholes’, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 305–310 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By Graham Speirs

La minería del siglo XXI requiere que ingenieros, consultores y proveedores brinden apoyo a promotores, desarrolladores y operadores para lograr una extracción y procesamiento de minerales segura, eficaz y con el menor costo posible. Este artículo técnico muestra el diseño, construcción y mantenimiento de un eje vertical, con una forma más rápida, económica y productiva de izar con cables guía, buzones de aluminio y sistemas de izado diseñados con tecnología de vanguardia.

Sep 30, 2017

By José Luis Calderón, Percy Arrosquipa

Compañía Minera Poderosa ha identificado una interesante oportunidad de generar valor y de mejorar tanto el clima laboral como el de relaciones comunitarias mediante el proyecto descrito en este artículo. El proyecto se orientó a motivar la incorporación de prácticas de responsabilidad social, tanto entre proveedores de bienes y servicios, como entre empresarios mineros artesanales en proceso de formalización. Como ejemplo, se analiza el caso del cofinanciamiento de la obra “Mejoramiento del sistema de agua para consumo humano del anexo Pueblo Nuevo”, que benefició a 195 familias con un servicio de agua de calidad las 24 horas del día. De este modo, se corrigió una fuente de conflictos sociales y se materializó una alianza para el desarrollo local entre la mediana minería y la minería artesanal. Por su parte, Asociación Pataz entregó certificados de donación, deducibles del Impuesto a la Renta, a los aportantes.

Sep 30, 2017

By Andrés Recalde

Dado que el riesgo social se ha convertido en uno de los principales factores de éxito o fracaso para un proyecto minero, las familias, comunidades y gobiernos locales en la zona de influencia se constituyen en actores primordiales de un proceso de relacionamiento y acuerdos que debe contribuir al mutuo beneficio. El Modelo o Acuerdo de impacto beneficio (AIB) es una propuesta metodológica desarrollada en Canadá desde 1970, que busca generar consenso entre la empresa minera y las comunidades impactadas social y económicamente por un nuevo proyecto, mediante la firma de un contrato en los que se enumeran los impactos y las medidas de mitigación que se efectuarán en contraprestación para evitar el daño. Los Acuerdos de impacto beneficio permiten guiar el relacionamiento entre las partes, controlar expectativas y mitigar el impacto social. La firma de una AIB es el inicio de la licencia social para operar (LSO), lo que la convierte en un activo intangible del proyecto.

Sep 30, 2017

By Juan Rayo

Minería sin residuos o Wasteless Mining (WLM) es una innovación tecnológica global que apunta a eliminar los riesgos ambientales generados por escombreras y relaves, por medio de una combinación de los procesos de explotación subterránea por hundimiento y de espesamiento de relaves hasta convertirlo en pasta. La condición ideal ocurre cuando ya existe una explotación a tajo abierto y se migra a explotación subterránea por hundimiento, en cuyo caso el déficit de volumen para alojar el relave en pasta lo suple el antiguo tajo. La cavidad resultante del minado por hundimiento puede contener algo más de 2/3 del residuo generado; el otro tercio se coloca en el tajo pre-existente, en obras subterráneas abandonadas, en un depósito sobre zonas de subsidencia delimitada por pretiles o en una relavera menor. Durante la explotación de mina por hundimiento, hasta extraer 1/3 de las reservas no hay cráter de subsidencia. Entre las principales ventajas de la WLM, el artículo cita: mínimo uso de suelo y quebradas para depositar residuos, bajo riesgo de filtraciones y/o producción de aguas ácidas, bajo consumo de agua, ausencia de vibraciones o polvo por voladura.

Sep 30, 2017

By Fábio Rogério do Carmo

O ar soprado é uma das principais utilidades responsáveis pelo processo de transformação do minério de ferro em gusa no Auto Forno. Para que ocorra o processo de redução o ar soprado é superaquecido nos regeneradores dos autos fornos a uma temperatura de 1.300°C. Este energético é fornecido na CSN-UPV pelos turbos sopradores da Central Termoelétrica nº 2 (CTE#2), área dos Motos Sopradores 1 e 2 e os turbos sopradores n°1 e 3 da CTE#1 que operam com a velocidade reduzida 24 horas soprando para atmosfera e consumindo vapor de 30Bar. Devido à obsolescência do sistema de ar soprado da CTE#1, alto custo de operação e risco para a segurança operacional, este trabalho apresenta o estudo do problema em questão, a metodologia utilizada para desativação do ar soprado da CTE-1 e a redução de custo.

Sep 25, 2017

By Samuel Vasconcellos

Existem vários tipos de compressores centrífugos de gás, mas em todos o sistema de controle de capacidade influencia diretamente a performance do compressor e também a capacidade máxima de compressão do mesmo. O Controle de Capacidade do Compressor por ser realizado a partir de válvulas tanto na sução bem como na descarga em forma de vent ou mesmo uma válvula em forma de recirculação. Todos os sistemas operam como forma de controle de capacidade mas o mais eficiente é por meio de controle por uma válvula na sucção do compressor, pois tanto a recirculação como um vent na descarga não reduzem o consumo de energia elétrica de forma eficiente pela vazão entregue. Neste trabalho trataremos particularmente de um controle de capacidade por meio de válvulas de sucção em compressores de nitrogênio centrífugos procurando uma forma mais eficiente de compressão e também elevar a capacidade de compressão.

Sep 25, 2017

By Humberto Celeste Gomes

Este trabalho irá apresentar os critérios e considerações que levaram a AMT decidir pela primarização de duas equipes de manutenção da área de Energia (equipe de manutenção mecânica das turbomáquinas e equipe de manutenção elétrica de SEP/RUG). Apresentará também os desafios de formação, treinamento e capacitação das equipes bem como abordará a avaliação dos ganhos do projeto. Ganho em produtividade: Aumento da produtividade da equipe com a redução de 11% da quantidade total de empregados e Ganho financeiro para a empresa em função de redução de custo fixo. Ganhos adicionais: Melhoria na qualidade dos serviços, com menor retrabalho e turn over; oportunidade de redução de contratação SPOT em outras atividades envolvendo equipamentos rotativos de menor porte (ex: bombas); Formação de uma base de técnicos para futuras promoções internas (inspetores, técnicos de manutenção dentre outras). Pontos de atenção: Serviços realizados fora do horário ADM pela equipe de manutenção; Formação de turno de revezamento na equipe de manutenção de Turbomáquinas em grandes paradas.

Sep 25, 2017

By Alencar de Andrade Soares

Este trabalho tem como objetivo descrever as ações que foram tomadas pela TKCSA com o objetivo de restabelecer a capacidade operacional plena do Gasômetro (BFG), pela sua estabilidade e, por conseguinte a sua continuidade operacional. Desde seu start-up, ambos os Gasômetros apresentaram vários problemas que impediram sua operação em plena capacidade; provocaram várias paradas para realinhamento, rebalanceamento, bem como repopeamento. Estas ocorrências interferiram fortemente na Geração de energia do complexo, devido a instabilidade dos Gasômetros, causada por irregular movimentação do pistão, provocando sua descentralização e desnivelamentos fora das tolerâncias aceitáveis, o que levou a TKCSA a limitar a operação dos Gasômetros e, mesmo assim ; sempre que descentralizava e ou desnivelava, era necessário novos ajustes (repopeamento e rebalanceamento). Tais eventos nestes importantes equipamentos, levaram a CSA a tomar várias ações conforme preconiza o IGEM (Instituition of Gas Engineer) passando por reparos estruturais e culminando com a troca do sistema de selagem dos Gasômetros.

Sep 25, 2017

By Joaquim Luiz Monteiro de Barros

Com base na atual situação de restrição de disponibilidade e do custo da energia no Brasil, sistemas tipo Heat Pipe (tubos de calor) tendem a ser cada vez mais utilizados na recuperação do calor dos gases de exaustão nos processos de produção de gusa, para o pré-aquecimento de ar/gás, aumentando a eficiência energética global do sistema e reduzindo o consumo de combustível. Esta tecnologia agrega uma série de vantagens, quando comparada com os trocadores de calor tradicionais, pois possui um design compacto, transferência de calor uniforme em toda a área de troca térmica, alto grau de vedação, de forma a evitar o risco de vazamento e mistura/contaminação entre os fluidos quente e frio.

Sep 25, 2017

By Wallace Ernesto Sant’Anna Ramos

Dentre as diversas tecnologias utilizadas para desinfecção da água uma das mais utilizadas em todo mundo são as Monocloraminas. O presente trabalho visa mostrar as vantagens e benefícios de se utilizar uma tecnologia combinada mais limpa, verde e eficaz para controle microbiológico sem causar danos ao meio ambiente, além de ser mais segura e confiável, para o processo e o ser humano.

Sep 25, 2017

By Cláudio S. S. Pinto

Em face do agravamento da situação da energia elétrica no Brasil, com disponibilidade cada vez mais restrita e custo cada vez maior, torna-se urgente reduzir o seu consumo onde possível. Ventiladores centrífugos de processo de médio e grande porte são grandes consumidores de energia elétrica e podem ter um elevado potencial para a redução do seu consumo. Este texto mostra como identificar a possibilidade de economizar o uso da energia elétrica em um determinado ventilador e que modificações ele necessita para cumprir este objetivo.

Sep 25, 2017

By Márcio Zamboti Fortes

A alguns anos os setores residencial e industrial tem se deparado com mudanças de paradigmas que tangem a necessidade de melhorias em suas atividades, com o intuito de desenvolver processos com menor impacto ambiental, sustentáveis e com eficiência energética, objetivando reduzir o consumo de energia elétrica. O uso de tecnologias baseadas em fontes renováveis para a geração de energia elétrica, tais como a solar e a eólica, tem apresentado-se como uma alternativa a ser implementada por estes setores para atender às exigências do mercado, se beneficiando da difusão da tecnologia e uso destes equipamentos, para a consciente utilização da energia elétrica. A instalação e avaliação de novas fontes de geração de eletricidade estão sendo desenvolvidas pelo projeto Cidade Inteligente de Búzios através da implantação de painéis fotovoltaicos e aerogeradores de pequeno porte em unidades consumidoras residenciais, comerciais e industriais e alguns resultados estão apresentados neste texto.

Sep 25, 2017

By Eduardo Luiz Sales Marinho

A Fábrica de oxigênio da AMT produz gases O2 e N2, utilizados no processo de produção de aço. Neste processo de fracionamento de ar, existe um compressor de ar que é responsável pela captação do ar atmosférico. Este compressor é do tipo centrifugo de 4º estágios de compressão, fabricação Hitachi, e tem capacidades de vazão de 114.000 Nm³/h e pressão de descarga 5.4 Kg/cm². Em Novembro de 2012, foi realizada inspeção no compressor e identificado trincas nas pás do impelidor do 4º st e perda de espessura de parede das pás do impelidor do 3º st de compressão. Houve perda da confiabilidade de operação do equipamento, sendo necessária uma ação para correção do problema. Depois de identificado a causa raiz das trincas,foi decidida a compra de dois novos impelidores com modificações no material para aumentar a resistência à corrosão. Na aquisição dos novos impelidores havia duas possibilidades: 1) Adquirir novos impelidores junto ao fabricante original do equipamento; 2) Adquirir novos impelidores por processo de engenharia reversa (levantamento de desenhos da peça desgastada para fabricação de uma nova) em conjunto junto com empresa especializada. Este trabalho irá mostrar os critérios e considerações que levaram a AMT decidir pela compra de novos impelidores por “Engenharia Reversa”, bem como, suas vantagens e riscos assumidos.

Sep 25, 2017