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By Rafael Valencia-Dongo, Ernesto Ramírez, Julio Tapia

Enfocado en una novedosa metodología de resolución de conflictos basada en la teoría de juegos, este artículo propone estrategias para generar un equilibrio estable entre empresa, Estado y comunidad. Tras evaluar la tipología y características de la conflictividad socioambiental por acción de líderes opositores a la inversión, se desarrolla un marco de resolución de conflictos a través de lo que se denominan pactos de contrapeso, que cubren los ámbitos de comunicación, gestión sociopolítica y fidelización del trabajador minero. Estos pactos permiten cambiar la percepción, incentivos y acciones de los actores, lo que incluye la acción de terceros legítimos.

Sep 30, 2019

By Armando Rivera, Ángel Cueva

Proyecto Mirador es una explotación a cielo abierto que requiere la construcción de vías, campamentos, plataformas, diques, canales, bandas transportadoras y otras facilidades, las mismas que implican remoción de suelos y su posterior adecuación en escombreras estabilizadas con técnicas de restauración ambiental. Mirador se encuentra en una zona tropical que presenta un promedio de precipitación de 2,500 mm anual y dos ecosistemas naturales: el bosque húmedo piemontano y el bosque húmedo montano bajo. En este documento se analiza cómo controlar la erosión con las especies de flora nativas, la tecnología a utilizar, la clase de suelo y la selección de plantas idóneas para cada ecosistema.

Sep 30, 2019

By Walter Estrada, Fernando Valencia, Jaime Luyo

La gasificación por plasma es un proceso térmico a alta temperatura en el que los desechos se descomponen en elementos fundamentales y compuestos simples en un entorno anaeróbico. El sistema presentado en este artículo actúa como un digestor al transformar las moléculas de carbono y otras sustancias en compuestos menos contaminantes. Se utilizó una mezcla de cianuro disuelto en agua como muestra de ensayo —procedente de aguas de una mina—, que se sometió al componente radiante de plasma, y se estudió la energía generada actuando sobre la purificación y transformación de las muestras.

Sep 30, 2019

By Ángel Nuñez-Meza, Juan Alfaro-Bernedo

La intención del trabajo reportado en este artículo es la de superar las limitaciones que conlleva no trabajar con modelamiento previo, base de datos y un enfoque sistémico. En atención a esta idea, el estudio desarrolló un software para dos circuitos (directo e integral). Como resultado, se recomienda desarrollar un software integral de toda la planta concentradora —chancado, molienda, flotación y eliminación de agua— con diferentes tipos de circuito, en un solo sistema (enfoque holístico); además de migrar a un modelo de servicio en la nube, con el objeto de poder contar con completa disponibilidad.

Sep 30, 2019

By Joel Ochoa, Miguel A. Montiel

El artículo da cuenta del estudio de un prototipo de placa de desgaste para chutes de transferencia con un nuevo sistema de sujeción. El sistema fue validado mediante el software Ansys. La innovación no solo está constituida por un nuevo diseño sino también por el tipo de proceso productivo para la fabricación del producto mejorado. Se incluyeron ensayos con torquímetro, que presentaron resultados favorables.

Sep 30, 2019

By José Vergara, José Espinoza

El objetivo principal de la técnica de precorte es generar un plano de debilidad que permita disminuir las vibraciones y gases producidos por las voladuras de producción, de modo que la calidad final del talud no sea vea deteriorada. Mientras que los modelos teóricos suponen limitaciones para diseñar la tronadura para el caso de un macizo rocoso fracturado, los modelos numéricos, aun cuando son complejos en su arquitectura, son una gran herramienta para analizar el comportamiento dinámico que se genera dentro del macizo rocoso al momento de desarrollar la detonación de los explosivos. Este trabajo tiene como objetivo mostrar los resultados obtenidos al aplicar programación en elementos finitos con programa Elfen, en diseños de precorte en roca fracturada.

Sep 20, 2019

By Daniel Soares, Rodrigo Moreira

En un escenario altamente competitivo, la innovación se ha vuelto esencial para la supervivencia sostenible de las organizaciones. Sin embargo, proyectos de esta naturaleza poseen características muy específicas, ya que presentan alto riesgo e incertidumbre en comparación con proyectos convencionales. Desde su concepción, las iniciativas de I&D deben gestionarse de forma diferente. En 2011, Nexa Resources reestructuró su área de Innovación y creó el Directorio de Tecnología, con el foco en la implantación de proyectos de I&D. Se desarrolló una gobernanza específica para la gestión de esos proyectos, donde se definieron y estandarizaron tanto los procesos de gestión como la estrategia de innovación que la empresa seguiría en su planeamiento estratégico.

Sep 20, 2019

By Manuel Viera

El modelo Viera-Hurwick es una herramienta para la valoración económica de activos mineros. Es práctica, de fácil aplicación y arroja muy buenos resultados para un proceso de compra-venta. Se presenta el caso de estudio real del prospecto Greenfield Manuelita I Ongon Patazun, que se evalúa con esta metodología a nivel de exploración básica. Después de aplicar técnicas tales como árbol de decisiones, flexibilidades, Hurwick, estadística bayesiana, Hoskold, opciones reales, entre otras, se concluye que esta metodología, por su simpleza, arroja buenos y rápidos resultados que concuerdan totalmente con otros métodos y son plenamente aceptados por el código australiano VALMIN de valoración económica de activos mineros.

Sep 20, 2019

By Leoncio Méndez, Jesús Arguijo, Juan José Frausto, Daniel Castruita, Daniel Aguilar

Minera Sabinas (Grupo Peñoles), localizada en Sombrerete, Zacatecas, México, produce concentrados de cobre y zinc. Su proceso es un circuito de conminución de quebradoras y dos molinos de bolas en circuito cerrado con hidrociclones seguido de un circuito de flotación, a partir de mineral polimetálico extraído de una mina subterránea. Su problemática consiste en que la recuperación por flotación disminuye significativamente cuando minerales con contenido de pirrotita son procesados. La flotabilidad natural de la pirrotita supera la cinética de flotación de las especies de cobre y zinc y limita la capacidad de la concentradora para generar concentrados vendibles. Este artículo presenta un diagnosticó de los problemas que se tienen cuando se procesan minerales con alto contenido de pirrotita, así como resultados de un programa experimental a escala laboratorio realizado en el CIDT de Peñoles y en sitio. La investigación se enfocó en definir un esquema de reactivos para poder procesar minerales con pirrotita en su composición. Compósitos de alta y baja ley de cobre fueron usados en la investigación. Se identificó el agua de proceso como una fuente de iones calcio y sulfato. Se desarrolló un esquema de reactivos orientado a promover la selectividad de las especies de valor respecto a la pirrotita, incluyendo tratamiento del agua de proceso.

Sep 20, 2019

By John Marsden, Mike Botz

A variety of modeling techniques can be utilized to forecast metal production at heap leaching operations. These approaches reflect a wide range of complexity, flexibility, time to implement, cost, and accuracy. For many operators, a spreadsheet-based modeling technique is attractive since the calculations are directly accessible, models can often be developed by site staff, and the results are generally easy to extract and interpret. The authors have developed a spreadsheet-based modeling technique that provides a high degree of flexibility, while still considering detailed operating information for ore properties, leach kinetics, scaleup factors, lift height, and in-heap metal inventories. The technique involves establishing kinetic leach curves for each ore type to characterize metal extractions, followed by application of separate metal recovery curves to define the rate at which leached metals exit the heap in pregnant solution, taking into account delays due to the in-heap solution inventory. At any point in time, the difference between total metal extracted and total metal recovered is equal to the in-heap inventory of the leached metal. This modeling technique is particularly useful for larger multi-lift heaps where delays in metal recovery are appreciable due to in-heap solution holdup. The technique is also applicable to sites with multiple heaps, leach cycles, and/or metal recovery plants (e.g., carbon columns for gold; solvent extraction for copper). This paper describes the modeling technique, including input data required and methods for defining kinetic leach curves and metal recovery curves. The technique is compared against an alternative spreadsheet technique using a simplified in-heap solution inventory calculation to forecast metal production, which has proven to be effective at a number of sites.

Sep 3, 2019

By Tung Vu, Michael Harrington

"The Regional Connector project is a complex subway light-rail project that runs through the heart of downtown Los Angeles, CA. The design-build contract was awarded in April 2014 to the Regional Connector Constructors (RCC), a joint venture between Skanska USA Civil West California District Inc. and Traylor Brothers Inc., and their designer team consisting of Hatch Mott McDonald (HMM) and subconsultants. The project broke ground on Sept. 30, 2014 and is expected to be completed in winter 2021-2022. The main components of the project consist of 6.4-m (21-ft) diameter twin-bored tunnels, three crosspassages, a 87-m (287-ft) long crossover SEM cavern, three new underground stations, and cut-and-cover tunnels along South Flower, Alameda and 1st Streets. The project map is shown in Fig. 1. The design and construction challenges associated with each of these main components are discussed in the following sections.Project designTunnels. The Regional Connector tunnels are located primarily within the Fernando formation consisting predominantly of extremely weak to very weak, massive, clayey siltstone. About 305 m (1,000 ft) of tunnels on the eastern end are in alluvium and mixed face of Fernando formation and alluvium. The tightest curve of the tunnel alignment is 178 m (583 ft) in radius. The tunnels were designed with a reinforced precast concrete tunnel lining (PCTL) to be used with an earth balance pressurized (EPB) tunnel boring machine. The PCTL ring is 5.5 m (18 ft-10 in.) inside diameter, 27 cm (10.5 ft) thick, 1.5 m (5 ft) long, and consists of five segments and a key. The segments were designed with 6,500 psi concrete, 80 ksi yield strength wire rebar, convex joint surfaces to enhance seismic performance, and a dosage of 1.7 lbs polypropylene microfibers per cubic yard of concrete for fire resistance. The rings are designed with a right ring and left ring pattern and a taper of 3.8 cm (1.5 ft) to allow for alignment curve negotiation. Figure 2 shows typical sections of the PCTL. The structural lining design was modeled using FLAC 3D. Four consecutive rings were modeled with 32 dowel connection. Loading considered in the lining design includes temporary ground load during excavation, long-term ground loads, seismic loads and train loads. The seismic loads on the PCTL were simulated with the racking deformation applied at vertical boundaries of the model. Due to variation of geologic condition along the tunnel alignment and different surcharge requirements, three different types of reinforcement (typical, heavy and extra heavy) were designed. The typical type PCTL was required in Fernando formation, the heavy type was required in alluvium or mixed-face condition, and the extra heavy type was required in alluvium and underneath the Japanese Village Plaza where a surcharge of 1,000 psf was required."

Sep 1, 2019

By J. Bilant, B. Carlson, N. Gow

"High-pressure grinding roll (HPGR) technology was evaluated to replace tertiary cone crushing at Coeur Rochester operations (Coeur Rochester Inc.) as an opportunity to improve silver recovery. In 2016 and 2017, onsite and third-party pilot programs were initiated to evaluate the impact on metallurgical recovery and heap leach performance of crushed product generated by an HPGR. In 2018, Forte Dynamics evaluated the HPGR laboratory metallurgical data from Coeur Rochester and all third parties to develop field-scale leach curves based on new crushing scenarios. The laboratory recovery test work data were consolidated and scaled to field conditions to determine projected heap leach performance. Based on the metallurgical testing conducted, the replacement of current tertiary cone crushers with HPGR technology has the potential to increase Coeur Rochester’s silver recovery rate by 8 percentage points, from 61 percent to 69 percent, and shorten the overall timing of silver recoveries from 20 years to just more than two years.The Rochester Mine, and associated valley fill heap leach facilities is an openpit silver and gold mine located in Pershing County, NV, approximately 42 km (26 miles) northeast of the city of Lovelock. In 2017, Rochester produced approximately 4.7 million oz silver (Ag) and 51,000 troy oz gold (Au). Ore mined at Rochester is either fed directly to the primary X-Pit crusher, crushed at an in-pit crusher system, or placed directly onto a heap leach pad as run-of-mine (ROM). Both crushing circuits are comprised of three stages of crushing to produce a nominal 3/8 in. ore. Primary crushing consists of jaw crushing while secondary and tertiary crushing are composed of varying cone crushers.Historical recovery rates of crushed Rochester ore averaged 61.4 percent Ag and 95.9 percent Au over a period of 20 years (Robinson et al., 2018). These rates were derived from third-party verification of in-house metallurgical test results, crusher production and heap leach production results from 1986 through 2004 in a private report for Rochester produced by KD Engineering Co., Inc. Recovery rates are regularly verified by compositing daily samples of ore delivered to each leach pad from the X-pit crusher, in-pit crusher and/ or ROM. A proportionate split of each sample is used to generate monthly composites for metallurgical analysis utilizing column leaching and bottle roll leaching. These tests are run in a manner analogous with production conditions and deliver test results that provide expected heap leach performance. As the Rochester oxide deposit has been mineralogically and metallurgically consistent, the gold and silver recovery trends have also been consistent over the life of the project."

Sep 1, 2019

By Tim McMahon

"A slurry is any combination of liquids and solids where solids make up more than 10 percent of the mixture. Mining operations create various types of slurries from processes such as dewatering, bitumen extraction in oil sands, concentrator plants, milling operations, tailings, lime addition and so on. The mines then transport these slurries through pipelines (Fig. 1).Slurry valves are used when the mine needs to transport ore a long distance and there are no other viable transportation methods, such as roads or railroads.Severe service valves must be used in slurry applications and they must be tested to ensure reliability. This article describes how Emerson designs and tests its Fisher valves for use in mining slurry applications.Slurry pipeline valvesWithin a slurry pipeline system, valves are required as part of the pumping stations, choking stations and isolation stations. There may be multiple pumping stations depending on the length of the pipeline or the terrain it crosses. Choking stations are used to reduce the velocity and the pressure in the pipeline, either before a pumping station or at the end of the pipeline, and to ensure the pipeline does not slack (remains full and pressurized). Isolation stations exist so that a pig (a device sent through a pipeline to clean or inspect the pipe) can be inserted or removed from the pipeline.Typical valves used in a slurry pipeline are severe service ball valves. The valves use floating balls that are held between the seats and are not pinned or permanently attached to the shaft that rotates the ball. The inside diameter of the ball typically matches the pipeline inside diameter, enabling the pipeline to be cleaned or inspected with a pig.They can be built to accommodate the high pressures required for the typical slurry pipeline. These pressures can require up to ASME Class 2500 valves and flanges. The valves can get qlarge, up to NPS 36 inches.Specialized segmented ball valves and slurry knife gate valves are also used in some slurry applications when pressures are lower, in the ASME Class 150-300 range."

Sep 1, 2019

By B. Boutilier, R. Mendoza

"First Majestic Silver Corp. (FMS) is a silver mining company founded in 2002 that operates exclusively in Mexico. It has six producing silver mines, one of which is the La Encantada silver mine (La Encantada) located in the state Coahuila. La Encantada is located near the southern United States border and 708 km (440 miles) north of the city Torreon.La Encantada is located in the Sierra Madre Oriental and is a high-temperature carbonate replacement deposit. Mineralization in La Encantada occurs in many different forms such as veins, chimneys, breccia pipes and reefs (mantos). Mineralization is mainly oxides of iron, zinc, lead and manganese, with high concentrations of sulfides at depth relating to two main intrusive events: the Milagros Intrusive and the La Prieta Skarn.Mining began in La Encantada during the 1950s with small vertical shafts, drifts and raises. It focuses on the high-grade silver zones using traditional hoists and extraction methods, before branching into two main separate mining camps: El Plomo and Penoles camp. Penoles, the previous owner, focused mainly on large ore bodies using post pillar cut-and-fill mining method to extract the higher-grade material. Due to the type of ground, irregularity of pillars, and rock conditions, large amounts of high-grade pillars had to be left in situ to ensure the stability of the excavations. The mined-out areas would then be filled with lower-grade material to assist in the stability of the secondary level. These room-and-pillar development entries were 2.5 m x 2.5 m (8.2 ft x 8.2 ft) and spaced every 10 m (32 ft), leaving a vertical pillar of 7.5 m (25 ft). First Majestic acquired La Encantada in 2006. After the acquisition of the mine, the company began the conversion of the surveying reference system from a local grid (Maria Isabel Shaft as 0,0) to the Nav27 coordinate system, and subsequently converted to the WGS84 coordinate system in 2015. Due to the extensive history of the mine, different areas were surveyed with different systems, causing significant challenges when designing the principal extraction levels, pillar heights and ramp locations. To overcome this difficulty, the entire mine was resurveyed and the old workings transposed to the new coordinate system, except for some inaccessible areas due to poor ground conditions or ground collapses. To further ensure pillar height and the safety of the mine workers, probe holes were drilled during the development process."

Sep 1, 2019

By Phil Rice, Mohammed Nasim, Richard Flanagan

"The Gateway Trans-Hudson Partnership (GTHP), a joint venture of WSP USA, Inc., AECOM USA, Inc, and STV Incorporated, is providing preliminary engineering services to Amtrak for the Hudson Tunnel project as well as supporting the NEPA process for getting the record of decision (ROD). This preliminary engineering design effort by GTHP includes geotechnical exploration and laboratory testing, design of structures, tunnel contract packaging and procurement planning.The Hudson Tunnel Project includes the construction of a new Hudson River Tunnel system and rehabilitation of the existing North River Tunnel. The new tunnel system will be constructed south of the existing North River Tunnel, from North Bergen under the Palisades to Hoboken in New Jersey, below the Hudson River, and connecting directly to Penn Station in New York (Fig. 1). The tunnel system is configured as two single-track tubes, intermediate ventilation shafts and cross passages in compliance with NFPA- 130 requirements. The adjacent surface alignment west of the Palisades will be constructed on viaducts, embankment and retained fills. The existing North River Tunnel (Fig. 2) consists of two single-track, electrified rail tunnels extending from tunnel portals in North Bergen, New Jersey to Penn Station in New York. Completed in 1910 by the Pennsylvania Railroad, the tunnel opened at the same time as Penn Station and the four, single-track, East River tunnels that connect Penn Station to Queens and onto Long Island and New England, respectively. Both tunnels in the existing North River Tunnel were inundated with brackish river water during Superstorm Sandy (Fig. 3), resulting in the cancellation of all Amtrak and NJ Transit service into New York City for five days. After the brackish water was removed from the tunnels, the residual chlorides and sulfates have had on-going detrimental impacts on the interior concrete and rail systems."

Sep 1, 2019

"The National Mining Hall of Fame and Museum (NMHFM) announced the class of 2019 National Mining Hall of Fame inductees. This year’s inductees, selected by the National Mining Hall of Fame’s Board of Governors, represent exceptional financial acumen in assembling several operations that formed the basis of a successful American mining company; conception and development of equipment which contributed to improved efficiency and mine safety; and unrelenting advocacy for the U.S. mining industry and its workers. These individuals, selected for being determined, forward-thinking innovators, doers and leaders have propelled the industry toward vastly improved safety and social responsibility.The Prazen Living Legend of Mining Award, named for renowned mining artist Gary Prazen, will also be presented at the ceremony. This award recognizes an individual or organization for significant and sustained commitment to educating the public about the relationship of mining to our everyday lives through educational materials, programming, and outreach.2019 National Mining Hall of Fame inducteesFrank Calandra, Jr. has devoted more than 50 years to the mining industry and he is an icon in ground control technology for the mining, tunneling and civil construction industries.From the ground up, his passion, sweat equity and shrewd business acumen have grown Frank Calandra, Inc. (FCI) and Jennmar from a single plant in Pennsylvania to a world-class enterprise with 25 plants employing thousands globally. As evidenced by Calandra’s more than 20 patents on ground control devices (not to mention the additional 80 patents his companies hold), his innovation and commitment to safety have made underground mining safer and more efficient. In the late 1970s and early 1980s, Calandra was instrumental in upgrading American Society for Testing and Materials (ASTM) standards in roof control for both state and federal regulations. Through his work with industry associations such as the National Mining Association, National Coal Council and Center for Energy and Economic Development, among others, Calandra has contributed his time, expertise and financial support to ensure a balanced political and regulatory climate for mining. Calandra is an inductee of the West Virginia Coal Hall of Fame."

Aug 1, 2019

By Chee Theng

"What would you do if you are an industry leader and disruptive technology threatens to overturn your business model? Although bearings and seals are in little danger of being displaced in the near future, one company is taking no chances in an age of digital disruption.“For SKF, digital transformation and the Industrial Internet of Things (IIoT) make this time right now arguably the most exciting time in our 100-plus years of history,” John Schmidt, president of SKF USA Inc., said during the SKF Technical Press Day in Philadelphia, PA.The company is not merely integrating digital technologies into its products and services but is taking a forward-looking, strategic approach. “To be successful, legacy companies have to undertake a process called digital transformation. It’s not just an IT initiative but is really about upgrading the strategic thinking,” explained Michael D’Argenio, vice president of digital transformation and customer experience at SKF Americas.Learning from those who went beforeD’Argenio cited the examples of two companies that saw entirely different outcomes in the face of digital disruption. The well-known case is that of Kodak, one of the storied brands in history, whose business was disrupted by the advent of digital photography. Although it invented digital photography, Kodak decided to box it up and put it on the shelf because it was scared of disrupting its business in photographic fim. Instead, it was disastrously disrupted from the outside.Less well known is the case of Encyclopedia Brittanica Inc., publisher of the longest-running English-language, general-knowledge encyclopedia in the world. Sales peaked at 120,000 sets in 1990, plunging to 8,000 sets in 2012. In 20 short years, it saw not one but two massive digital disruptions. The first was in 1993, when Microsoft published the first digital interactive encyclopedia on a CD-ROM, called Encarta, priced at just $99. The second was in 2001, when a communitycurated, free website called Wikipedia launched. Taking the opposite approach from Kodak, Encyclopedia Brittanica looked at its industry, its company and its customers through the lens of the new technologies, made a prediction about the future and, based on that prediction, took a bold move. Having identified its core value proposition as the delivery of reliable, high-value, verifiable knowledge, Encyclopedia Brittanica replanned, restructured and rebuilt its company from the ground up to deliver that same value proposition, only in a different way. It stopped producing the only product that it had known for 244 years and began producing digital products that it sold to educational institutions.“There is a lot to learn from the Encyclopedia Brittanica case,” said D’Argenio. “The company embraced its market change, it embraced its customer change, and it rethought what it needed to do to be successful. Because it owned that disruption internally, it was never disrupted from the outside. It continues to operate today and is as profitable as it has ever been.”"

Aug 1, 2019

By Mike Moody

"No matter what type of ore is being extracted from a mine, mucking with front loaders can be accompanied by wet fines that cling to every surface. Once loaded into a hopper or conveyer transfer chute, viscous material can quickly build up on the walls to create bottlenecks, clogging the chute and causing expensive downtime.Clearing material from hoppers, chutes, bins and vessels can be done using manpower and tools on hand, but safety experts recommend considering a solution that prevents exposing workers to potential hazards. Operators at modern mining sites, such as the Eagle Mine, located in Western Marquette County of Michigan’s Upper Peninsula, understand that using specialized equipment reduces worker exposure, offers the safest mode of production and provides the most cost-effective lasting results.“Safety is a top priority for us,” said Ted Lakomowski, lead reliability technician at the Eagle Mine. “When we experienced clogging and downtime at the processing mill, the crew naturally swung into action to resolve it, but we immediately sought a safer long-term solution.”Stope mining for nickel and copperOwned by Lundin Mining, a globally diversified base metals mining company headquartered in Toronto, ON, Canada, the Eagle Mine is the only primary nickel mine in the United States, producing 1.5 percent of the world’s total nickel production. The first operation permitted under Michigan’s Part 632 Non-Ferrous Mineral Mining Law, it opened in 2014 and is expected to produce 163 kt (360 million lbs) of nickel, 134 kt (295 million lbs) of copper and small amounts of other metals over its estimated nine-year lifespan.The company extracts approximately 2 kt/d (2,200 stpd) from the underground nickelcopper mine using a bench-and-fill stoping process. Accessed from the surface by specialized underground trucks, the vehicles carry about 45,400-kg (100,000-lb) loads through a 1.6-km (1- mile) long and 5.4-m (18-ft) diameter ramp shaft descending into the earth at a 13 percent grade. Stoping is a bottom-up method that involves systematically blasting columns of loosened ore that is then mucked by front loaders into trucks and backfilled using cemented and uncemented rockfill."

Aug 1, 2019

By H. Gerry Stephenson, Devin Castendyk

"One of the most important environmental issues associated with contemporary openpit mining is the closure of mine pit lakes, and the perpetual legacy these lakes can potentially generate. Ideally, successful pit lake closure includes the following:• The water quality within the pit lake, plus surface water and ground water discharging from the pit lake, meets premining or other acceptable water quality conditions of the receiving environment. • The termination of all active treatment processes.• The return of the pit lake to the government for long-term care and maintenance.• The release of the mining company from all future liabilities associated with the pit lake.• The return of the environmental bond to the mining company.• The reuse of the pit lake for some post-closure, beneficial purpose.The achievement of these goals is known as walk away pit lake closure.Peer-reviewed publications of successful walk away, pit lake closure provide mining companies with the ability to address public concerns regarding the safety of pit lakes which commonly occur during the permitting, operations, and closure phases of mining. To date, most published work on walk away, pit lake closure work has occurred in the coal mining sector in Germany and Australia (McCullough et al., 2009; Jones and McCullough, 2011; Kumar et al., 2013; Schultz et al., 2013). In North America, examples of walk away, pit lake closure are not widely discussed in the literature despite there being excellent examples from the coal mining sector in Alberta, Canada (e.g. Pleasure Island, Black Diamond, East Pit, Sphynx, Robb, Lovette, Siltstone and Sterling), and from the iron mining sector in Minnesota in the United States (e.g. Portsmouth Lake, see MNDNR, 2018). Although seldom included in discussions of pit lakes from the metal and coal mining sectors, the aggregate and fabricated-stone mining sectors also produce pit lakes, and there are numerous examples throughout North America where these pit lakes have been successfully closed and transformed into post-mining resources (Vandenberg, 2018; Crossman, 2019). The difficulty of finding these good examples in the literature makes it challenging for companies to respond to public and regulatory questions regarding pit lake closure and reuse. As such, there is a pressing need to document the motivations and approaches used in examples of successful, walk away, pit lake closure in North America so that the mining industry, at large, can learn from these examples and can better address public concerns."

Aug 1, 2019

By Marcelo Marchesi Martinelli, Caio Henrique Vidigal

Gasômetros são equipamentos de grande valia para aumento da eficiência energética e ambiental de empresas siderúrgicas integradas, sendo estes equipamentos responsáveis pelo controle da pressão do gás resultante das transformações dos processos siderúrgicos, controle este realizado através das variações de volume abaixo dos pistões. Quando não há disponibilidade de operação dos gasômetros faz-se necessário o uso de torres de queima para controle das pressões das redes de gases. Em dezembro de dois mil e dezoito fora realizada a troca da selagem do gasômetro de gás de Coqueria da ArcelorMittal Tubarão, que utiliza a tecnologia M.A.N. (Selo a óleo). Utilizando técnicas da metodologia Lean, modificando o mindset e alterando antigos paradigmas foi possível realizar a manutenção, de forma eficaz, em 32 dias, 28 a menos que o último trabalho similar realizado e 13 dias a menos que a meta proposta para a parada, aumentando a recuperação de gás de Coqueria, maximizando ganhos de geração elétrica e minimizando a exposição a riscos ambientais associados a parada. As ideias apresentadas neste artigo são de grande valia para a evolução do pensamento crítico e sistêmico sobre a manutenção, não só em gasômetros, mas em todo o contexto de realização de atividades já consolidadas.

Aug 1, 2019