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By D. Spitty

Mining companies often have many disparate systems and repositories of data in their organization for planning and scheduling outbound mining supply chains. To optimize ore quality, throughput, transport logistics scheduling and delivery to contract, planning teams need to model and manage the value chain accurately and achieve a consolidated, enterprise view of operational performance. Planning teams coordinate a complex series of activities to ensure production forecast accuracy. They also negotiate and execute complex contracts often with disconnected and limited visibility of production forecasts, quality, and variability with little ability to accurately market potential product specifications over longer time horizons. This market is becoming increasingly dynamic, with increasing variability and the time for planning teams to react is decreasing. This is driving the need towards using science to generate the necessary scenarios required to support the decisions made by planners on a frequent basis. Resource-to-Market is a highly flexible, user-configurable supply chain management system for the mining and metal processing industries. This provides an integrated view of the supply chain that supports the dynamic nature of planning in a mining company, embraces variability of elements across the supply chain with the ability to optimize across all the functional areas of the operation to enable optimal decision making for often competing objectives such as throughput, quality, cost, revenue and profit.

Feb 23, 2014

By M. A. Oskouei

Draglines are dominant machines and the most electricity consumers in surface coal mines. With the growing price of energy, environmental concerns, and the high sensitivity of mine profitability to dragline productivity, any improvement in efficiency of draglines can be beneficial for mines. Research has shown that operator skills have a significant impact on energy efficiency of loading machines. This study suggests a method to identify the key parameters that lead to differences in operator energy efficiency (responsible parameters). First, correlation analysis is used to identify parameters that are correlated to energy efficiency. Second, linear regression of a difference matrix is used to determine responsible parameters. Since this method is based on pair-wise comparison of operators, equal number of cycle is required for pairs of operators. Complete case analysis (CCA) is used to handle missing data problems. The final conclusion is made after removing the effect of random sampling and by considering all pairs of operators. Identifying responsible parameters can improve operator training programs. The suggested method is illustrated with a case study using field data.

Feb 23, 2014

By J. Paraszczak

Application of teleoperated and automated (or ?autonomous?) mobile equipment in underground metal mines is a promising avenue for overcoming some of the challenges facing mine operators. These include, but are not limited to, the issues related to safety and health of underground workers, better use of the shift time leading to increased productivity, skilled manpower shortages, and remoteness of some mine sites. Autonomous load-haul-dump machines and trucks offer several benefits over man-operated ones, but their use at their full capacity is a challenging and complex task. This paper makes an overview of commercially available equipment and systems and their applications. It examines factors affecting adversely availability, utilization, and production efficiency of autonomous vehicles and compares them to conventional man-operated machines. Technical and operational aspects are discussed and their criticality is analyzed. Based on that, recommendations concerning means and measures that may help raise operational effectiveness are given. It is stressed that due to a scarcity of publicly available information on the performance and cost of autonomous loading and haulage operations, more field studies and in-depth analysis are needed.

Feb 23, 2014

By A. Festa

Secondary crushing often gets good press for its increases in energy efficiency and SAG milling rates but for a project considering this option the proposed benefits soon get overshadowed by implementation concerns. Reverse engineering from the published case studies is risky unless the reader understands the drivers impacting stability and operability of the circuit. This paper discusses the features of secondary crushing for Greenfield and Brownfield SAG mill grinding circuits. It is the author?s view that secondary crushing rarely adds value to a Greenfield project and restricts future expansion. Its application is best retro fitted to Brownfield operations where the benefit gained for capital expended is excellent. Two case studies are presented to reaffirm these statements. The first case study shows that the implementation of partial and total secondary crushing increases SAG mill power efficiency and it offers substantial incremental increases in milling throughput with staged capital investments for the crushing and grinding circuits respectively. The paper provides a critical analysis of process conditions for secondary-crushed grinding circuits, with particular emphasis on Brownfield circuit retrofits. Furthermore, the second case study quantifies the economic impact of secondary crushing on circuit design for plant start up and it illustrates the limit imposed on plant expansion.

Feb 23, 2014

By C. Ernst

The underground operation at Barrick?s Cortez Mine, located near Elko, NV, required the construction of a 12 foot diameter smooth-lined ventilation shaft. Barrick preferred to mechanically excavate from the ground surface without putting people in the excavation and considered blind drilling by Frontier-Kemper Constructors the best option. Design and construction challenges arose throughout both the excavation and lining stages. A large portion of the rock to be drilled was highly fractured. Important risks that were addressed included water loss into the formation, zones of squeezing ground, damage to drilling tools caused by blocky ground and fallout, and potential hazards during cast-in-place concrete lining. Detailed explanations of these challenges and the methods used to overcome them will be described.

Feb 23, 2014

By L. Schlink

Impacted waters, often complex, are created in mining which at some point in the mine life cycle will need to be attended. The simplest and most cost effective method of handling impacted water is to reuse it as makeup water for operations. At the end of mine life, operational reuse will not be an option and the impacted water will require treatment to achieve alternative reuse goals. Conventional mine impacted water treatment is successful in removing unwanted constituents but create brine and sludge that may require special handling or additional treatment, resulting in additional liabilities and costs. Freeport-McMoRan Copper & Gold has taken an approach to water treatment that focuses on transformation not concentration. The Water Treatment Test Facility located at Sierrita Mine has three test plants that are piloting the mine impacted water transformation process. Two plants have been designed for the removal of calcium and sulfate with products of gypsum and sulfur. The third plant removes metals from process water and transforms them into marketable metal sulfides. The transformation, rather than concentration, of mine impacted water solutes greatly reduce long term risks.

Feb 23, 2014

By J. F. Brune

This is a shortened version of the paper ?The Methane-Air Explosion Hazard Within Coal Mine Gobs published in the 2013 volume of SME Transactions (Brune, 2013). This paper analyzes the explosion hazard resulting from the formation of methane-air mixtures in the mined-out gobs of underground longwall coal mines. Evidence from numerous mine explosions suggests that explosive methane zones can form within longwall gobs. Explosions and fires resulting from these methane accumulations have led to severe and fatal injuries to the miners, including the explosion of the Upper Big Branch mine in West Virginia, where 29 miners lost their lives. The paper also reviews current research on numerical modeling of gas flows in longwall gobs and outlines how targeted injection of nitrogen into gobs can effectively reduce the volume of such explosive methane zones. The paper concludes that comprehensive monitoring of gas compositions along the accessible fringes of the gobs along with inertization, improved ventilation schemes and further research are necessary to control this explosion hazard and make mining operations safe.

Feb 23, 2014

By S. D. Abbott

Mines are filled with a mixture of gases, some of which are toxic, flammable, or explosive. Others serve as early reporters of impending problems. Mines monitor these gases in order to ensure the safe, efficient operation of the facility and avoid losses or disasters. Two different approaches to monitor these gases have historically been taken. One kind of device measures the amount of each gas present by using selective detectors (e.g. handhelds and spectrometers). Another kind separates the mixture of gases into the individual constituents, then measures the amount of each gas present (e.g. gas chromatographs). Handheld units are the most widely used, but gas chromatographs are the most powerful yet underutilized units available to enhance mining operations. There are many misconceptions about the nature, applicability and proper use of each type of device, and little data is available. Up to this point, many people had only the manufacturers? claims to guide them. This study was undertaken to clarify the range of applicability, important characteristics, and value in use of these units in real-world situations. An additional goal of the study was to provide ways to evaluate comparative data, and thus aid mining operations in choosing the most beneficial and reasonable ways to use such devices in various situations and contexts.

Feb 23, 2014

By A. K. Martin

Adaptive management can be described as a structured, iterative process of robust decision making in the face of uncertainty, with a goal of reducing uncertainty over time through system monitoring. Adaptive management is a tool which can be applied to not only change a system, but learn about the system (Holling, 1978). Adaptive management has been used in ecosystem management for years and guidance is provided in a variety of handbooks and publications. Adaptive management can be applied to industrial facilities and mines through the use of an adaptive environmental management plan (AEMP) and associated practices. The goal of this paper is to provide an explanation of how the plans and practices support regulatory agency approvals and permitting, span the life-cycle of mines, manage uncertainty, and assist in addressing mining impact and legacy issues. AEMPs and associated practices are useful tools to address the uncertainties in identifying, evaluating, and managing impacts of proposed new and modified mining facilities undergoing environmental review. Once a proposed project is approved, the AEMP continues as a living document, being informed, revised, and adapted by the operations. The AEMP can serve as an ongoing management tool for describing and evaluating environmental impacts, continuing in operations into post reclamation. If initiated during planning and environmental review of a project (and in some locations such as the United States [U.S.], the preparation of an Environmental Impact Statement (EIS)), the AEMP becomes a basis to identify, monitor, and manage potential project environmental impacts. Development of an AEMP for an operating mine is also beneficial since there are generally developing and ongoing environmental issues at those facilities as well. Over time, the AEMP is adapted to changing requirements and conditions including those anticipated and unanticipated. Ever increasing scrutiny of mining projects and the complexities of the EIS process highlight the uncertainties inherent in impact predictions. In making the momentous decision of initial project approval, these uncertainties can discourage the regulatory agencies? actions and create stakeholder anxiety and controversy about a project. A well-designed AEMP can support the decision to approve an EIS and enable a project to move forward. Additionally, an AEMP can inform financial assurance estimates and revisions over the life of a mine providing all parties including the citizens of the surrounding communities with greater confidence that potential environmental impacts and risks will be well managed.

Feb 23, 2014

By D. Spitty

There are enormous complexities with mine planning and the problem itself presents a huge challenge to the existing mine planners performing this activity. Mine planning optimization supports planners to determine ?What are the best increment excavation sequence and the best material blending combination such that throughput, quality, cost, utilization and Net Present Value (NPV) targets are met?? It is achieved through using an advanced scientific approach that has been specifically adapted to address the mine planning dilemma.

Feb 23, 2014

By L. Sandbak

The Turquoise Ridge Joint Venture (TRJV) is located in northern central Nevada, and is situated within the Basin and Range province, near the northeast end of the Osgood Mountains (see Figure 1). The TRJV mine consists of typical Carlin type- gold mineralization characterized by low strength rock of altered limestones, siltstones, and mudstones. The weak nature of the ground facilitates the underhand cut and fill mining methods. TRJV has been working to optimize ground support and mechanize top cut drift sizes and eliminate operating hazards associated with jackleg drilling. Safety Factor analysis based on bolt strengths has allowed us to pursue larger sized top cut drifts and to evaluate bolt length sizes and spacing. Switching from jackleg sized drifts of 10?W x 10?H to a mechanized 12?H x12?W top cut drift design has the potential to decrease overbreak, provide more uniform drift design sizes and bolt patterns, and increase ore production by at least 38%.

Feb 23, 2014

By F. J. Sotillo

Mining in Peru is mainly concentrated on metallic and polymetallic ores of gold, copper, lead, zinc, silver, tin, iron, etc. However, little has been done to develop extensive and rich non-metallic or Industrial Minerals deposits with the exception of some silica and phosphate deposits. This paper presents the characterization and metallurgical studies for the development of a feldspar deposit. These studies showed that the special characteristics of the ore, such as high porosity, high Al2O3 content, low clays content, and sized material allowed us to obtain commercial products applying relatively simple and low cost concentrating unit operations. The characterization studies showed that the feldspar products contained no quartz and about 90% of albite (NaAlSi3O8). The 14x40-mesh size fraction product analyzed 5.91% Na2O, 22.56% Al2O3, 65.73% SiO2, 0.65% K2O, 6.50% CaO, and 0.40% Fe2O3; whereas, the 40x150-mesh size fraction product analyzed 6.22% Na2O, 24.30% Al2O3, 60.80% SiO2, 0.91% K2O, 7.06% CaO, and 0.54% Fe2O3. These products could be used for manufacturing glass, ceramics, refractory, and filters in different applications. In addition, Middlings, could be used as insulation material due to its porosity (bulk density of 0.828 Kg/dm3), analyzing 4.46% Na2O, 15.7% Al2O3, 67.2% SiO2, 2.57% K2O, 3.94% CaO, and 4.24% Fe2O3. The material showed a sphericity of 0.77, a roundness of 0.68, and acid solubility of 13.3025% on only washed and 2.72% effective for clean material suitable for use in these applications. No selective accumulation of the valuable mineral was observed at any specific size fraction. However, iron and titanium bearing impurities trended to concentrate in fine fractions (minus 70 mesh -212 µm-). Metallurgical studies demonstrated that this feldspar ore required sizing at 14x40 mesh and 40x150 mesh to render commercial products. In the case of the 14x40-mesh size fraction, the process involved magnetic separation, gravity separation, and flotation for feldspar (direct flotation) using a blend of primary and condensate amines. However, the reverse flotation for mica-biotite and iron bearing minerals was also possible using petroleum sulfonate. The metallurgical process for the 40x150-mesh size fraction required magnetic separation and reverse flotation of iron and titanium bearing minerals, the feldspar being reported in the sink material. Commercial products from this feldspar deposit for glass, ceramics, refractory, and filtration; and for the manufacturing of insulation material were obtained.

Feb 23, 2014

By J. V. Belke

There are many aspects of a grinding mill supply and installation that can result in the mill not operating as intended, resulting in unplanned shutdowns, poor reliability and headaches for all concerned. One of the largest aspects, both in criticality and physical mass, is the mill foundation; if not properly specified, designed and constructed the mill operation will be compromised. The mill foundation starts with the design specification and loading diagram supplied by the mill builder. The importance of understanding these documents and how to apply them is critical for the start of any mill project. When designing mills with a GMD the foundation must be properly modeled to ensure that all interactions of the mill and motor structures, foundation and subsurface strata behave in the intended fashion. All of the previous efforts can be laid to waste if the construction of the mill foundation is poorly handled. Mill foundations are typically the most massive concrete structure at a processing plant and can easily cause nightmares for inexperienced contactors. This paper explores some of the more important facets along the lifecycle of the grinding mill foundation.

Feb 23, 2014

By E. O. Jacobs

A coupled solid and rock fracture mechanics model is used to analyze the blast driven fracture propagation phase, predict propagation rates, and directly measure shockwave and particle velocity. The study incorporates quasi-static pre-stress conditions for different depths below the surface. The scaled experiments include dynamic material properties and quasi-dynamic fracture mechanics which are shown to significantly affect the fracture propagation. The study was performed using three-dimensional cube-type laboratory models fabricated from Polymethylmethacrylate (PMMA). The test cubes are loaded with explosives and resulting fracture networks are studied. The dynamic evaluation of the spatial crack system is monitored using a high speed image camera. An experimental model set-up is designed to indicate the pre-stress effect on deep borehole blasting and is shown that the pre-stress conditions have a decisive influence on fracture profiles and orientation. It is found that shockwaves rapidly exceed the slower dynamic fractures and a majority of cracks occur due to detonation pressure. Experimental testing using different parameters validate that explosive fracturing can predict the outcome of fracture and crack propagation in any rock type with known material properties. This can be accomplished under great stress conditions deep below ground surface. The experimental study results can be applied to a variety of industries such as mining and quarrying, tunneling, oil and gas, and construction.

Feb 23, 2014

By K. Zhang

Real option value (ROV) method is considered to be more practical and advanced compared to net present value (NPV) method in evaluating a mining project, in particularly when there is substantial uncertainty in the commodity market as well as possible operational flexibility embedded in the project. Usually, it may take months or even years for the commodity product to be available in the market after the mining activation decision is made. The impacts of postponing the delivery of commodity product on the mine?s ROV and NPV are assessed based on the proposed real option method. Postponing the delivery of the products leads to declined NPV and ROV compared to the non-postponing scenario and extended postpone results in higher lost values in NPV and ROV. For a mine with lower mining cost, by postponing the delivery, the exercising threshold of commodity price is lower because the mine owner anticipates that commodity price may rise during the time of postponing. A mine with higher mining cost requires a higher exercising price threshold to ?lock up? the profit when there is ambiguity of market situation due to the postponing of the delivery.

Feb 23, 2014

By M. A. Bartkoski

Today?s surviving companies are being pushed to a heightened level of excellence due to market changes. Therefore, new business strategies must be explored. This paper offers a sequenced plan to retool, empower, and organize the entire team for a common goal. Integrity Process is an operating system that is very comprehensive and is integrated in every part of the business. It relies on a detailed prevention concept intertwined with accountability that produces individual efficiencies and team effectiveness. Integrity Process focuses on the importance between working from commitment motives versus compliance fears. The results are balanced in priority and truly yield a win-win for the owners, management, workforce, and the community. Integrity Process can and is being used in any industry that is challenged to optimize the relationship between people and process.

Feb 23, 2014

By F. Mielli

Over the last three years there has been an increase in mining congress and conferences focusing on water management. Water in mining is a key concern for mine managers and operations, and we are now seeing this operational dilemma escalated to the level it deserves. According to Frost & Sullivan research, mining water and wastewater treatment and its related technologies will be a U$3.6 Billion global market in 2016, which translates the importance of this issue. Looking at the current mining trends, some factors increased the importance of water in mining operations, including: ? Future mining investments will be located in geographical locations where water is scarce (water stressed areas) ? A decline in grade will increase the intensity of mineral processes and therefore increase the use of the water ? Increased sustainability and regulations will extend the control/monitoring of water during the entire mine life cycle representation of the mine water flow system. A water balance has several benefits/objectives in a mine operation: ? Mine planning/simulation of mining scenarios/climate change Production optimization ? Minimizing strategic and operational risks ? Social license to operate ? Water-smart mine planning ? Target: water neutral mines ? Benchmarking within and between sites ? Sharing knowledge/technology transfer ? Reporting/communications ? Permitting/Compliance

Feb 23, 2014

By A. Anani

The goal of hot mix asphalt (HMA) design is optimal material blending to meet Superpave specifications. HMA cost minimization has being modeled as linear programing (LP) (Awuah-Offei et al 2011) and mixed integer LP problems (Brown et al, 2012) and solved with commercial software such as LINDO and CPLEX. Often these software, which are designed to solve general optimization problems, have licenses that cost thousands of dollars. The objective of this study is to develop a novel solution algorithm to the HMA optimization problem presented by Brown et al. (2012), which will negate the need for expensive commercial packages and is specific to this problem. This novel algorithm is based on the branch and bound algorithm for solving mixed integer problems. The algorithm is incorporated into a software package with an easy-to-use graphical user interface. The developed algorithm is validated using a real-life HMA problem. Using this solution algorithm will save companies thousands of dollars, otherwise used to purchase software licenses.

Feb 23, 2014

By S. Philipp

This paper describes several variants of placement and design, from a technical and economic point of view, of shafts, ore bunkers and drifts near shafts of a Russian potash mine. Advantages and disadvantages of the position of different workings are shown as well as an analysis of stratigraphic and geological layers and their use for excavating pit bottoms, haulage drifts and bunker installations. The potash mine consists of two hoisting shafts and one service shaft. The hoisting capacity of one of these skip shafts is planned to be approx. 7 Million tons of crude potash salt per year. Both shafts together will have a hoisting volume of about 14 Million tons. When the mine will increase their highest level of production, it will be one of the biggest potash mines in the world. The skips, the hoist drives and the bunker near the shaft will belong to the largest ones worldwide, too. This paper specifies the features of such a double skip shaft pit in detail and demonstrates problems, which depend on the fact that the pit bottom is in a depth of nearly 1200 m.

Feb 23, 2014

By E. Hsieh

Proximity detection in the open pit mine can be used effectively as an operator assist strategy which improves digging production through enforcement of best practices, although it is normally thought of first as a safety tool, and second as a step toward full automation when combined with object avoidance.

Feb 23, 2014