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By T. D. Barkand

A recent coal mine elevator accident resulted in serious injuries to four passengers. The miners struck the ceiling of the elevator car as it collided into the overhead structure at an estimated speed four times faster than normal. In response to mine hoisting accidents, safety authorities have required additional protective devices on new and existing mine hoists and elevators. This paper examines supplemental safety circuits and new devices designed to provide ascending car overspeed protection on mine hoists and elevators. These devices provide needed protection that eliminates the hazard or significantly reduces the potential of a mine hoisting accident.

Jan 1, 1995

By Jack O?Hearn

A liquid and solid waste management plan for an operating uranium ore processing mill was developed to efficiently and effectively dispose of existing solid wastes and related, affected surface and ground water resources. The goal of this management plan was to achieve satisfactory clean up of these existing wastes ad their by-products as well as to prevent similar situations from occurring in the future. An existing, modern system of synthetically lined tailings ponds, constructed after many years of mill operations, now provides an approved site for the disposal and containment of waste streams currently generated by the mill. This system was thought to be readily adaptable to serve as a key element of the waste management plan. The potential presence of extra capacity in these ponds could eliminate or reduce expenditures for new facilities required solely for proper management of liquid and solid wastes generated by operations prior to construction of the modern tailings ponds as well as for a range of anticipated future operations.

Jan 1, 1984

"INTRODUCTION The characterization of groundwater hydrogeology is a common component in feasibility studies, geotechnical investigations and regulatory permitting for mining operations. The lithology at a location of interest may include several discrete water-bearing units; and the means of isolating each for testing can be accomplished through the use of inflatable packers. Consideration for testing during drilling program planning and communication between all stakeholders is essential to ensure that the Mine, Drilling Contractor and Hydrogeological Testing Specialist (Specialist) are ready to perform packer testing when the call is made to mobilize. Often, the notice to mobilize can be delayed and then occur with little warning due to the issues that can occur during drilling of very deep boreholes, as well as other factors. Hydrogeological investigation reports and journal articles generally discuss testing methods and results, with limited information available describing the planning and coordination of the field testing program, as evidenced by the lack of references cited below. The source of inspiration for the subject matter of this paper is grounded in the author’s past shortsightedness; with the hope that others not share similar misfortunes but experience success through thorough preparation for their future hydrogeological testing programs. The sections below focus on the planning stages of a field investigation using inflatable packers, including considerations for site specific conditions, designation of stakeholder responsibilities, and communication of testing expectations. Following these sections is a presentation of two examples of successful field programs and lessons learned in addressing problems encountered along the way. PRELIMINARY PROGRAM PLANNING & CONSIDERATIONS From the onset of planning for drilling programs, the Specialist should be in communication with the Mine to review plans and identify fatal flaws which could impede collection of hydrogeological data. Preliminary scope decisions can significantly affect the budget and duration of hydrogeological field programs and may dictate the means by which the field data is collected. The issues that need to be considered include the following factors. Testing Objectives The setup of the packer tool is dependent on the testing objectives. Is the goal to estimate bulk aquifer hydraulic conductivity or to identify discrete discontinuity hydraulic characteristics? Are groundwater samples needed? The answers to these questions affect selection of test interval length and what instrumentation might need to piggyback on the packer tool. Identifying the testing goals initially will provide adequate time to prepare packer equipment for mobilization. Borehole Size While inflatable packers come in many shapes and sizes, some sizes are more readily available and easier to procure on short notice. Packers for NQ and HQ size boreholes have been historically easy to procure and are commonly used in exploration drilling. Packer equipment is available for smaller holes, but it becomes more difficult to fit instrumentation down-hole as the borehole size decreases. This is particularly a consideration if collection of groundwater samples is required. In addition, risks of losing the hole or equipment downhole are greater for smaller boreholes. Larger boreholes require larger packers and clearly require more effort and heavier capacity machinery to manually manipulate due to the increased size."

Jan 1, 2017

By P. Songfack

In this work, the slurry flow in the ball mill is solved with Navier-Stokes' equations and the marker and cell technique (MAC), which tracks the fluid-free surface. Considering different planes in the radial and axial directions, this numerical approach leads to the direct calculation of the slurry velocity profile, mill holdup, and volumetric flow in the ball charge and pool. The MAC technique takes as input, the results of a direct three-dimensional simulation of the motion of grinding media, and in turn, provides a detailed knowledge of the hydrodynamics of slurry flow through the porous structure of ball load. This technique is a new approach to the mass transport problem that overcomes the limitations of indirect studies such as residence time analysis and holdup measurements.

Jan 1, 1994

By N. Rowlands

The importance of mineralogical and chemical characterization of fine particles in the fields of mineral and metallurgical processing is discussed. Emphasis is placed on electron beam analysis techniques including electron diffraction and energy dispersive analysis with special reference to the scanning trans- mission electron microscope. The correct choice of instrument depending upon particle size, composition and nature of sample is stressed and the analytica1 capabilities of different types of instruments are evaluated. Recent applications of electron beam equipment to processing problems are presented and the paper concludes with a review of new developments in the fields of surface analysis and micro-diffraction.

Jan 1, 1985

By Takuya Tani, Tomoyuki Aoki, Kazuo Saskai

"The authors have proposed a unique methodology in the evaluation of rock mass stiffness for the range of five to twenty meters ahead of the tunnel face, with the use of small diameter inclinometers. The inclinometers are installed at the tunnel crown at a pre-determined constant interval, about one meter behind the face in order to obtain the slight change in inclination angles during tunnel excavation. This method was developed as a daily control measurement such that the geological condition and its possible change ahead of the face could be detected early by monitoring the trend of inclination angles. This paper describes the results of the ground stiffness ahead of the tunnel face evaluated at a mountain tunnel construction site. This stiffness is evaluated automatically and displayed visually by the current system equipped with a result display screen, together with a warning message against a weak zone when detected. 1. INTRODUCTION In a conventional planning of a mountain tunnel, according to the Japanese Standard (JSCE, 2006) seismic refraction surveys from the ground surface are performed and tunnel support patterns are then designed based on the seismic wave velocity. The resolution of the velocity profile estimated by this technique, however, is poor as the tunnel overburden becomes large. The tunnel face is therefore often encountered by unforeseeable fault zones or weak rocks. Such an unpredictable weak zone occasionally causes the collapse of the tunnel face. Clarifying the forward geological information during excavation is hence significant for safe and well-controlled construction. According to the geological conditions ahead of a face, auxiliary methods typified by forepiling and face bolting could be preliminarily prepared for prompt execution. For the purpose of acquiring forward geological information, pilot borehole drilling and seismic reflection methods represented by the TSP (Tunnel Seismic Prediction) or HSP (Horizontal Seismic Profiling) are often applied. Those exploration are carried out near the tunnel face for a couple of days. This often leads to the interruption of excavation procedure and has no small effect on the construction schedule. On the other hand, some forward ground prediction methods in the daily control measurement have been developed e.g. by Schubert et al. (1995). In this method, tunnel displacements in the direction of the tunnel axis are used together with the crown settlements. We have tested their method at a few of our tunnel projects and found difficulty in the evaluation of the forward ground condition due to insufficient resolution of the axial displacement measured by a total station theodolite that we usually use for the tunnel measurement. We have therefore developed a novel methodology of monitoring slight inclination at the tunnel crown near the face, so that the forward ground conditions can be predicted and evaluated as part of a routine measurement procedure."

Jan 1, 2016

By T. Bednarski, T. McCallum

"Physical impurity transfer in solvent extraction (SX) has a significant impact on operating costs, electrowinning (EW) performance, and cathode quality. Some operations use a wash stage to limit impurity transfer by diluting the entrained pregnant leach solution (PLS) to prevent direct transfer to EW. Wash stage operating conditions vary impacting impurity transfer. A number of factors impact dilution efficiency including mixer continuity, wash aqueous acidity, and organic quality. The impact of these variables on dilution efficiency was studied and compared to current industry practice. INTRODUCTION With the exception of iron, impurity transfer in copper SX is due to PLS carryover in the loaded organic via aqueous entrainment and crud movement. The quantity of impurity transfer is influenced by many variables including operating set points, organic quality, and settler housekeeping. Crud management and treatment is a common practice aimed at minimizing transfer of impurities to EW. Crud is a complex solid-stabilized emulsion of aqueous and organic[9]. As such, it contains a large aqueous component and the associated impurities (from the PLS). A common practice is to remove interfacial crud to prevent movement. Additionally, mixer continuity can be altered to enable compaction and improve the efficiency of interfacial pumping[10]. Understanding the factors impacting aqueous entrainment and optimizing the available controls should be a key focus for any operation. Aqueous entrainment in the loaded organic can be impacted by: • Mixer continuity • Mixer organic/aqueous (O/A) ratio • Mixer speed and impeller type • Organic and aqueous depths • Specific settler flow • Use of settler internals (picket fences, coalescing packs) • Organic quality • Design and operation of loaded organic tanks Conventional thought is to run the E1 mixer in aqueous continuity to reduce aqueous entrainment. Generally, O/A ratios close to 1:1 result in improved metallurgical and physical performance. Mixer speeds should be chosen to achieve acceptable stage efficiencies while minimizing over-mixing. Organic depths can be increased in the E1 stage to increase retention time and minimize aqueous entrainment. Settler internals can also be used, but require maintenance to maintain effectiveness. The quality of the plant organic inventory will impact physical performance. Poor organic quality can lead to higher phase disengagement times increasing impurity transfer to the electrolyte. Additionally, the design and operation of the loaded organic tank can impact impurity transfer[8]. Despite the variables that can be used to reduce aqueous entrainment and crud movement, impurity transfer is still an issue in some operations. For these operations with high PLS impurity concentrations, a wash stage may be beneficial to manage impurity transfer. Understanding factors impacting wash stage performance is important to optimize performance and limit impurity transfer."

Jan 1, 2016

By Joseph Moses Botbol

The disposition of world mineral resources is such that a vital need exists for both the most efficient development of existing resources and the rapid disclosure of as-yet undiscovered resources. The technological developments described in this report are directed primarily toward the acceleration and increased efficiency of mineral-resource exploration program. In the past decade the use of computers in the mineral industry has grown exponentially. Most computer applications in mineral exploration are designed to be implemented either before or after data collection. Few, if any, computer applications are designed to be used during the collection of data. One major reason for the lack of development of computer applications in this area is that comunications links do not exist between computing systems and the remote areas that host mineral-deposit exploration programs.

Jan 1, 1975

By D. Tao

Coal is a major source of energy in the U.S. and more than 51% of the electricity used in the country is generated from coal. Coal cleaning prior to combustion is necessary and often accomplished using wet physical processes at coal preparation plants to remove impurities such as ash, sulfur, mercury. However, the resultant clean coal product still contains a significant amount of impurity due to the fact that impurities are not well liberated from coal particles ranging from several millimeters to inches in size at which wet cleaning processes take place. A cleaner coal product can be obtained if a cost-effective dry process is developed to further clean pulverized and thus better liberated fine coal at the power plants prior to its combustion. The benefit of such a process is a significant reduction in the cost of expensive post-combustion chemical cleaning processes such as flue gas scrubbing employed to meet the stringent environmental air quality regulations. In this study, a novel rotary triboelectrostatic separator (RTS) was investigated for its application to dry cleaning of fine coal samples acquired from the power plants in the state of Illinois. The pulverized fine coal contains well liberated ash and pyrite minerals and is an ideal feed to the triboelectrostatic separator for further cleaning without the use of water or any chemical reagents. The proprietary rotary triboelectrostatic separator (RTS) is characterized by an innovative high efficiency rotary charger, charger electrification, laminar air flow, and specially designed electrodes. Compared to existing triboelectrostatic separators, the rotary triboelectrostatic separator offers significant advantages in particle charging efficiency, solids throughput, separation efficiency, applicable particle size range, etc. Testing with several fine coal samples has demonstrated that this technology can significantly reduce ash content with a process efficiency similar to or better than froth flotation. Important process parameters such as charger rotation speed, injection and co-flow rate, feed rate were investigated for their effects on separation performance.

Jan 1, 2010

By S. Davis

It has been accepted almost as dogma that sampling contributes most of the error to fluctuations in gold fire assays. Differences in assay results on pulp material from the same sample interval are frequently regarded as evidence of the presence of the so called "nugget effect" or relatively coarse gold particles. It is true that if coarse gold particles are present they contribute to substantial sampling fluctuations, but while the process of sampling is probably the major source, the analytical process cannot -be completely ignored as a possible contributor to erratic assay results. In order to maintain a stable assay process, the analytic part of the system must be kept in control as well as the sampling and preparation part. One way of monitoring the performance of the analytic system is to systematically assay standard material whose sampling characteristics are carefully controlled. Gold assay standards are not prepared nor can they be prepared to account for both sampling and analytical errors. It is not possible to send coarse material to a lab for preparation (which includes both the processes of comminution and splitting) followed by fire assay, to make inferences only about the fire assay process. Because most gold ores are very heterogeneous, sampling errors would in most cases completely mask the contribution of the analytical errors. Assay standard material is prepared only to assess the accuracy and variability in the fire assay process.

Jan 1, 1995

By D. A. Stanley

Researchers at BCD Technologies and the University of Alabama have applied three statistical techniques to the information contained in a large database of measurements from a phosphate ore processing plant. The rust, Principal Components Analysis (PCA), replaces many measured variables with a few fundamental and un-correlated variables. The second technique, Projection to Latent Structures (PLS), is an extension of PCA that explores the relation between variables identified as either independent or dependent. The third technique, Cluster Analysis (CA), is applied to the results of the PCA or the PLS calculations, and identifies individual data clusters that represent uniform operating conditions in the plant. All three statistical methods can be seen as geometrical operations on the data viewed as points in space. A Viewer gives a corresponding graphical presentation of the data points. This paper describes the use of the above three techniques and the Viewer to explore part of the phosphate flotation database.

Jan 1, 1998

By Basar Arioglu, Jaeung Kim, Mehmet Öztürk, Jinmoo Lee, Dongho Lee, Taek-Kon Kim

"Istanbul Strait Road Tube Crossing Project (Eurasia Tunnel) includes 3.34 km of a bored double-deck tunnel under the Bosphorus Strait, at a maximum depth of 106 m from the sea level, and 1 km of twin NATM tunnels on the Asian side. The region’s variable geology, hydrology and propensity for seismic activity, combined with high water pressure and large-diameter/double-deck tunnel configuration, make the Eurasia Tunnel one of today’s most challenging and complex projects under construction. Due to the site’s proximity to the active North Anatolian Fault, the tunnel is designed to withstand a 7.5 magnitude earthquake. The tunnel penetrates through both the Trakya bedrock (on both European and Asian sides) and the alluvial sediments at the bottom of the channel. The tunnel is designed to accommodate differential displacements by introducing seismic/flexible joints at proper locations at the transition zones between rock and soft soils. Tunnel fire is also a significant design consideration for undersea tunnel due to that the rubber protecting it in close proximity of the seismic joint should resist a fire for long term safety and durability. This paper mainly focuses on the design for method of tunnel response analysis in transverse and longitudinal direction against seismic demands relating with the seismic joints. INTRODUCTION Istanbul Strait Road Tube Crossing Project (Eurasia Tunnel) will build and operate a roadway tunnel under the Borphorus connecting Kazlicesme on the European side and Goztepe on the Asian side, to provide additional road-access across the Strait and consist of three main parts as shown in Figure 1."

Jan 1, 2016

By Phillip J. Maddex

Transportation is a major part of yours in the industrial minerals industry. Whereas federal income taxes merely take 50 per cent of your firms profits, transportation cost may take 50 per cent of the gross realization - selling price plus transportation - on your product, f. o. b. customers plant.

Jan 1, 1969

By Z. Sample, S. Kaushik

"INTRODUCTION Industries around the globe have been making significant advancements in recent years due to innovations in automation technology. With the implementation of modern automation technology, professionals in process automation or plant operations can expect significant and exciting change, and the mining and mineral processing industries are no exception. From 2000 to 2010, the International Council on Mining & Metals (ICMM) reported that an increased output and increased value of most metals has resulted in a rise in global metal and mineral process industries from $214 billion to $644 billion. [1] Since most productivity increases in mining and mineral process industries have been achieved through the ability to process lower grade ores with improved efficiency and larger equipment, these industries have begun to adopt advanced automation and control technologies. Despite a growth slow-down, the mining and mineral processing industries are poised for continued and sustainable growth and development due to an increasing demand for energy minerals and emerging technologies requiring minerals and metals previously not demand. However, as these industries becomes more automated, new challenges are arising on the horizon. DEMOGRAPHIC TIME BOMB John Payne from BP is credited with first using the term Demographic Time Bomb to describe the upcoming crisis in the process industry in finding experienced operations personnel. From a survey of 912 mining professionals, Stratum International found that a mere 0.4% of senior level candidates were between the ages of 25 and 34 and a similar proportion aged over 75 years. This indicates that there is both a deficiency of young skilled workers and a skilled workforce that is retiring earlier than the previous generation. Combined with data published by the US Department of Labor stating that the median age of the mining workforce is approaching 50 years old, this implies that these skilled mining and mineral process professionals are an aging population with irreplaceable knowledge and experience that are expected to retire in the next 5-10 years. While it is projected that the labor pool will be sufficient to fill open positions, the real question is if this young workforce will have necessary skill sets and experiences."

Jan 1, 2015

By Brad Grothen, Lok Home

The choice of TBM type is never easy, but it becomes especially challenging when faced with a hard rock tunnel with expected high water flows and pressure. Slurry Shield tunneling has a long history of being used in these conditions to minimize the risk, though this method has brought with it other risks along with cost considerations. At recent projects around the world, another method has been proven to effectively manage these project risks without utilizing Slurry Shield tunneling: Shielded, NonContinuous Pressurized (NCP)-TBM tunneling in rock with a comprehensive grouting program. In this paper, the authors will analyze the use of Shielded NCP TBMs at projects around the world as compared with slurry shield tunneling in rock under water pressure. Recommendations will be given in order to establish a clear picture of the optimal tunneling method.

Jun 13, 2021

By Christophe Bragard, Rebecca Reeve

The Regional Connector Transit Corridor (RCTC) Project is a 1.9-mile-long metro light-rail extension project that traverses the historical core of downtown Los Angeles, California. This project aims to improve mobility throughout downtown LA with fewer transfers for riders. It is designed to connect two existing rail lines for a more seamless travel. The project consists of twin bore tunnels, three new stations, and is scheduled to be completed in 2022. The design-build contract was awarded to the Regional Connector Constructors (RCC) in 2014, a joint venture of Skanska and Traylor Bros, Inc. with Hatch Mott MacDonald as the designer. One of the challenging aspects of the project was the construction of a crossover cavern in a narrow public right-of-way surrounded by historical structures. RCC used Sequential Excavation Method (SEM) to construct the crossover cavern measuring 287 ft long by 58 ft wide by 36 ft tall. The initial lining of the cavern featured a 12 in. fiber reinforced shotcrete lining. The initial lining was separated from the final lining by a hydrocarbon resistant membrane, as specified by the standard requirements of Metro. The cavern features a cast-in-place final lining with a thickness of 5 ft 9 inches in the invert and 18 inches in the crown and walls. The structure also features a nonload bearing plenum slab and interior walls for ventilation.

Jun 13, 2021

By R. D. Bartlett

Large open pit mines in desert climates, such as the Phelps Dodge Morenci copper mine in Arizona, can create groundwater cones-of-depression of considerable size and :ability. The hydraulic containment provided by the groundwater depression prevents migration of process solutions into the surrounding regional aquifer. Copper leach operations that fall within the groundwater depression may not require costly lining if passive containment can be demonstrated. An approach is presented in this paper that was successfully used to demonstrate passive containment. The approach includes a combination of groundwater modeling and a water balance analysis of leaching operations failing within or immediately near the open pit.

Jan 1, 1999

By S. K. Kawatra

In order to meet federal air pollution guidelines, it is necessary to remove a considerable quantity of sulfur from many North American coals. This may be accomplished by oxidizing the sulfur to water soluble forms, followed by washing the coal. Selective oxidation of the various sulfur forms can be accomplished through the use of a variety of types of bacteria. In this paper, the various bacteria and their requirements are described, and processes using bacteria to remove coal sulfur are discussed.

Jan 1, 1987

By Enrique Jelvez, Pierre Nancel-Penard

The traditional way of generating open-pit mine production schedules has several limitations. This work addresses the design and production-scheduling problem by considering minimum operational space requirements under a Direct Block Scheduling approach to generate extraction sequences that satisfy the operational space required. For this, traditional formulations were extended by including a new set of constraints that generate operating spaces for mining equipment to move and extract material. Then, a heuristic algorithm produces close to optimal practical pushbacks. This proposal was applied in a case study, and the results show its ability to generate practical production schedules without sacrificing expected return, obtaining differences in terms of Net Present Value (NPV) lower than 1% when compared to the traditional approach.

Jun 25, 2023

The engineering company's participation in quality assurance in the mining industry is twofold. Not only must it have such a program to ensure the necessary high standards for its own design and construction of a minerals processing plant, but it is also responsible as the "engineer" for both the selection and the quality of purchased equipment which goes into that plant. It is in this latter role that the engineer finds the most difficulty, or controversy, since while it is relatively easy to control his own performance, this is not ncessarily so when dealing with companies, all with their own ideas or standards. The engineer has perhaps rather reluctantly become more involved with the quality assurance of purchased equipment. This is because he has been used to writing performance type specifications and expecting the equipment manufacturer to provide the degree of quality, and control of that quality, for the product to meet the specified operating conditions. However, this has sometimes placed the manufacturer in a difficult position since to remain competitive in today's market conditions, he cannot always insist on product improvements or options which may in the long run be vital to reliable operation of the equipment.

Jan 1, 1982