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By G. P. Hand

The purpose of this paper is to bring to your attention the various kinds of high performance graphites available today, their characteristics and possible applications. These materials are products of a proprietary high temperature technology developed by Superior Graphite Company. We feel we have only begun to tap the potential of this technology and the utilization of the resulting products. During the course of the paper, we shall investigate high purity, high performance graphites made from raw materials such as mined natural graphites, synthetic graphites and petroleum derivatives. We shall define their characteristics and resulting benefits to current applications, along with applications currently under development. It is our desire to stimulate speculation and development of current high performance graphites and their applications as well as ideas for new high performance products and applications. First, a little background about the process. The technology was developed through a concentrated R&D effort which culminated in 1976 in the construction of a unique furnace capable of continuously processing tonnage quantities of granular carbons at temperatures in excess of 2,500 degrees C. This process is capable of refining various carbonaceous raw materials, including natural graphites, to levels of purity and consistency that were previously unattainable in commercial quantities. Carbon contents in excess of 99.9% are currently being produced on a continuous flow-through basis. Since beginning operation in 1977, this plant, located in Hopkinsville, KY, has been expanded in stages to its present capacity of producing over 45,000 tons of purified graphites and graphitic carbons per year. In addition to the purification process, the technology used allows the introduction of selected elements into the carbon/graphite structure to provide additional benefits. Elements of interest include boron, silicon, copper, iron and rare earths. The characteristics of and applications for some of these products will be discussed later.

Jan 1, 1990

By T. J. Lutz, S. Gallagher, J. R. Srednicki, J. J. Sammarco

The Illuminating Engineering Society of North America reports that an underground mine is the most difficult environment to illuminate (Rea, 2000). Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) are conducting ongoing studies designed to explore different lighting technologies for improving mine safety. Underground miners use different visual cues to escape from a smoke-filled environment. Primary and secondary escapeways are marked with reflective ceiling tags of various colors. Miners also look for mine rail tracks. The main objective of this paper is to compare different lighting types and ceiling tag colors to differentiate what works best in a smoke-filled environment. Various cap lamps (LED and incandescent) and lasers (red, blue, green) were compared to see which options resulted in the longest detection distances for red, green and blue reflective markers and a section of mine rail track. All targets advanced toward the human subject inside of a smoke-filled room to simulate the subject walking in a mine environment. Detection distances were recorded and analyzed to find the best cap lamp, laser color and target color in a smoke environment. Results show that cap lamp, laser color and target color do make a difference in detection distances and are perceived differently based on subject age. Cap lamps were superior to lasers in all circumstances of ceiling tag detection, with the exception of the green laser. The incandescent cap lamp worked best in the simulated smoke compared to the LED cap lamps. The green laser was the best color for detecting the tags and track compared to the red and blue lasers. The green tags were the easiest color to detect on the ceiling. On average, the track was easier for the subjects to detect than the ceiling tags.

Jan 1, 2013

By John S. Lagarias

When ore bodies are faulted or mill feed turns refractory, mining managers and engineers act vigorously to convert imminent failure into eventual success. The recent proliferation of onerous "environmental" regulations and restraints is likewise a threat to successful mining enterprise, in some ways more insidious and dangerous than the problems presented by natural obstacles. The regulatory burden has become so heavy that a pall of pessimism covers much of the mining enterprise. In this paper we frankly recommend a Pollyanna approach, making not just "the best of it" but directing the whole environmental process: first, to improve our planning, engineering, and operating procedures; and, second, to demonstrate the need for modification of laws and regulations which are intolerably burden-some to both the mining industry and the public. It is customary for government officials and environmentalists to point out how great are the new environmental regulations and how successfully these have improved the natural environment in particular and the quality of life in general.

Jan 1, 1978

By J. M. Manka

American mining companies operate many drum hoists that hoist from various depths with varying payloads. This paper will review the procedure of selecting optimum wire rope constructions for these existing hoisting installations. Selection for proposed installations along with recommended hoisting parameters will also be presented. To achieve this optimum rope performance, preventative and corrective maintenance procedures will be reviewed along with examples of rope problems and their causes.

Jan 1, 1992

By S. S. Xue

A study has been conducted to remove iron from sulfate solutions using Eichrom's Dipex® extractant, P,P?-di(2-ethylhexyl) methanediphosponic acid (H2DEH[MDP]). It is found that this extractant can effectively and selectively extract ferric ion from highly acidic solutions. Ninety-nine percent of the iron was extracted from a simulated feed solution in a single stage. The separation factor, Fe/Zn, was 10 6 Over 90% of the iron in a loaded organic can be recovered in an aqueous solution by reductive stripping. This paper presents the experimental results. A new process for iron removal using Dipex extractant is described and discussed.

Jan 1, 1999

By Desiree Willis

At 6 percent downgrade to a low point beneath California?s Sacramento River, the Lower Northwest Interceptor Sewer was a difficult project from the outset. Project owner Sacramento County Regional Sanitation District (SRC-SD) planned to excavate the V-shaped tunnel in two sections using an earth pressure balance (EPB) machine in soft ground. Muck removal, due to the steep downgrade, was a tricky proposition. ?We did look at muck cars, but determined they were not the best option due to the relatively steep slope of the tunnel alignment. The safety benefits of conveyors on this job were obvious, as there were not the potential hazards associated with muck cars traveling on an incline or derailing,? said Steve Norris, senior civil engineer for SRCSD The successful project represented one of the first instances of a conveyor system being used for a soft ground tunnel boring machine (TBM) application. Several projects in California, including a recent tunnel completed in 2009, have highlighted a growing acceptance of conveyor muck removal in a variety of ground conditions. Conveyors offer higher system availability than more common methods, such as muck cars, as they allow for continual operation of the TBM. The design of conveyor systems must, however, take into account the differences in material between soft ground and hard rock, including belt cleaning features, sealed transfer points and other elements.

Jun 1, 2010

By Christopher R. Winter

Mining companies have sharpened their refocus on their tailings management strategies in recent years. Mining companies with tailings storage facilities that use the upstream construction method have been challenged to track the evolution of industry standards, assess risks, revise design, and communicate design revisions with regulators. While many aspects of best practices and industry standards have evolved in recent years as an attribute of continual improvement, the controlling standard in the design of many upstream dams is understanding the foundational strengths of hydraulically deposited tailings. Following best practices and industry standards, Hibbing Taconite Company managed by Cleveland-Cliffs, began the re-evaluation of foundation strengths underlying a system of upstream dams at the company’s iron ore mine tailings storage facility in northern Minnesota. Initial steps in the re-evaluation require reanalysis of design parameters and recommendations by the Engineer of Record to the Owner, which was followed by a series of meetings with the Technical Review Board to determine an initial path forward. Once a path forward and preliminary design parameters were determined, the Owner engaged with the State Dam Safety Engineer to discuss and seek approval of the plan. With continuous regulatory engagement throughout the process, further refinement of the design parameters for the hydraulically-placed tailings foundations underlying upstream dams began with field and lab geotechnical investigations. Following a review of risk assessments and trigger actions response plans, Hibbing Taconite revised its tailings storage facility operating plans and budget for the coming years. Based on the findings of the re-evaluation, reanalysis, and refinement of parameters, a paradigm shift was realized with the hydraulically placed tailings foundation strengths underlying the upstream system of dams. This paper explores the path that the Hibbing Taconite Company followed to understand the paradigm shift and construct downstream improvements. The plan involved tailings re-characterization, dam design revisions, operating plan reconciliation, budget revisions, wetland permitting, dam safety permit amendments, storm water prevention plans, borrow materials studies, new concrete decant structures and the pursuit to recognize and be consistent with industry standards.

Feb 1, 2024

By Lei Pan, Venkata Atluri, Xuming Wang, Yuesheng Gao, Jan D. Miller

The wetting characteristics and water film stability at the talc surface have been studied, particularly the effect of polysaccharides such as guar gum, starch, and dextrin. Talc is a gangue mineral in the flotation of base metal sulfide ores, precious metal sulfide ores, and platinum group metal (PGM) sulfide ores. Talc surfaces were investigated using surface analysis techniques including atomic force microscopy, high-speed video bubble attachment measurements, and wetting film stability measurements using a synchronized tri-wavelength reflection interferometry microscope (STRIM). In the presence of polysaccharides, there is a significant increase in bubble attachment time at the talc surface, but only a slight change in contact angle, which suggests that polysaccharide depression of talc is due primarily to the slow rate of bubble attachment and not due to a change in contact angle. The critical rupture thickness (hc) for a hydrophobic talc surface was found to be 56 nm, while the hydrophilic phlogopite surface of similar structure has an equilibrium film thickness (he) of 25 nm. At low polysaccharide concentrations, the wetting films formed on the talc surfaces were unstable, but at high concentrations the wetting films became stable with similar thickness values as the critical rupture thickness, and bubble attachment did not occur. However, it was found that the critical and equilibrium film thickness values do not change significantly with the polysaccharide type or concentration. The results from this research help us understand further details of film rupture and displacement during bubble attachment.

By K. T. Brashear, N. Ripepi

"Over recent years, specifically following the MINER Act of 2006, an increasing number of manufacturers of underground mine seals in the United States have begun using a form of pumpable cement or shotcrete to create barriers separating the working and abandoned sections of underground coal mines. This seal material, while generally considered to be homogenous and solid, contains a network of microcracks, voids, and delaminations. Generally, it has been assumed that methane (CF4) leakage around these seals is a result of movement around the boundary interface between the seal and surrounding strata. Using a perfluorinated tracer compound, perfluoromethyl-cyclohexane (PMCH), the movement of gases can be monitored through seal material to observe how gases move though the material, both intact and with faulting in the material. This paper documents two large experiments where the movement of PMCH was monitored in the field, along with modeling confirmation using 3D visualization software. INTRODUCTION According to a report in 2007, there were over 14,000 active mine seals in underground U.S. coal mines alone (Zipf, Sapko, & Brune, 2007). These seals are used for both ventilation and safety purposes, to direct the flow of air away from the abandoned area of the mine and to help eliminate the propagation of explosions that can occur on the outby side of the mine seal. The atmosphere on the outby side of these seals typical consists of low levels of methane that have the potential of producing leakage along the face of the seal on the inby side. Methane leakage around mine seals has historically been attributed to the permeability between the seal and mine interface (McPherson, 1993). According to the United States Bureau of Labor Statistics (BLS) between 2003 and 2012 an average of 17 deaths occurred annually in underground bituminous coals mines. The only time during the ten-year period where the fatalities were higher than the average was in 2006 and 2010, years which had three major explosions occurring in underground coal mines in West Virginia and Kentucky. Two of the explosions were propagated through the mine by seal failure or methane leakage around newly poured seals (Light, et al., 2007) (Gates, et al., 2006). These recent events, and new regulations regarding seal strength (MINER Act), have created a need to monitor the condition of underground mine seals. BACKGROUND Measuring the permeability of solid materials, such as concrete or seal materials, can be a valuable tool in the field of non-destructible testing (NDT). By using an inert gas, such as nitrogen, injecting the gas into a solid structure, and measuring the resultant flow rate and pressure differential, this can provide valuable information about the structure. Studies have shown permeability can be affected by the stresses applied to the structure, as well as temperature and moisture (Choinska, Khelidj, Chatzigeorgious, & Pijaudier-Cabot, 2007) (Abbas, Carcasses, & Olliver, 1999)."

Jan 1, 2015

By Alvaro Veizaga, Samuel Cuellar

In recent years, Industry 4.0 has generated a change in the way companies in various industrial sectors design, produce and deliver products and services, and is focused on the interconnection of systems, the advanced access and management of large amounts of data in real time, and the implementation of emerging technologies such as the Internet of Things (IoT). Artificial intelligence (AI), machine learning (ML), digital twins (DT), robotics, virtual and augmented reality (VR/AR), among others [1]. DTs are accurate and dynamic virtual models that replicate physical systems, where it is possible to simulate and optimize operations before implementing real-world changes [3]. These features make it possible to reduce investment costs, minimize risks and improve strategic decision-making. These benefits are of utmost importance for tailings storage facilities (TSF), since they are facilities aimed at the safe storage of tailings and with the constant need for growth [4]. This paper evaluates the applicability of a DT in a TSF from a conceptual perspective, providing the advantages of its implementation, but also the barriers identified in the industry based on the authors’ experience.

Feb 1, 2025

By David X. Zhang

This paper describes the results of using shear flocculation and flotation known as aggregative flotation technique for the enrichment of coal-derived char produced from mild gasification process. Aggregative flotation is a separation process which involves the use of suitable aggregating liquid under the action of high shear forces to render hydrophobic surface of coal-derived char particles to aggregate in an aqueous slurry. The fine carbonaceous particles are aggregated into larger floes while the impurities remain hydrophilic. In subsequent flotation process, the char aggregates are then separated from mineral matters by aeration in the flotation cell. The floatability of char aggregates and removal of mineral matters from chars are studied in a lab scale flotation column cell. The effect of various operating parameters on the aggregative flotation responses is presented. Emulsification of aggregating liquid using high intensity agitation and ultrasonic energy provides excellent aggregating liquid dispersion and increases selectivity for char aggregation. In subsequent flotation process, it results in significantly increasing the flotation rate of char aggregates. The microscopic examinations of bubble attachment to coal-derived char particles under various aggregating liquid dispersion levels were conducted by induction time measurement. The distributions of hydrophobicity of char particles and char aggregates prepared under various aggregating liquid dispersion techniques were measured by film flotation. The char particles prepared under high intensity emulsification attach at significantly faster rates to air bubble and with lower mean critical wetting surface tension than that of char with direct aggregating liquid addition. An interrelationship of increasing in flotation rate/combustible recovery with decreasing in induction time, mean critical wetting surface tension and dispersion of hydrophobicity on the char particles and char aggregates were obtained.

Jan 1, 1992

By Charles B. Manula

This paper describes the development of a mathematical model for simulating the behavior of a longwall coal production system. The longwall simulator is a design simulator incorporating both deterministic and stochastic methods to calculate: (a) the size and density of support; (b) the cutting force, power requirements and haulage speed for the loader-shearer; (c) the conveyor size, speed and power requirements; and (d) delay generation at head and tail-gates and the longwall face.

Jan 1, 1978

By M. S. Klima

A 25-mm diameter dense-medium cyclone was tested to investigate the effects of geometry and operating conditions on cyclone performance when processing -150 I'm coal. The emphasis was on examining those variables (e.g., flow rate and inlet velocity) which impact the separation kinetics (specifically the number of g's and the mean retention time) and the occurrence of apparent bypass. Apparent bypass, indicated by partition curve "tails", results from the short circuiting of the feed coal to one or both of the product streams and represents a loss and/or contamination of the clean coal. This paper presents the results for this series of tests.

Jan 1, 1993

By W. C. Hirt

Selective flocculation was used to produce superclean zinc concentrate with minimized silica contamination. Research was carried out on a flotation concentrate from the Jersey Miniere Zinc Company (JMZ) in Gordonsville, Tennessee. The material was first dispersed with sodium silicate and then causticized tapioca starch was used to selectively flocculate the sphalerite, leaving the silica in suspension. This technique has been applied commercially to iron ore beneficiation but has never been used for processing zinc. The feed material assayed 0.45% Si02. Use of 0.56 kg/tonne (1.13 lb/st) of sodium silicate and 0.070 kg/tonne (0.141 lb/st) of causticized tapioca starch resulted in 98.2% zinc recovery in a purified zinc concentrate assaying 66.0% Zn and 0.24% silica. The present target level for silica contamination in JMZ zinc concentrates is 0.3% Si02. This work has shown that selective flocculation offers a potential method for cleaning flotation concentrates, particularly where low silica products are required.

Jan 1, 1993

In the screening process, used to prepare particles for many applications, shape is known to have a significant effect. The degree of flakiness of construction aggregates has been considered particularly important. The objective of this research was to find values of operating parameters that optimize the separation of flaky from non-flaky particles by slotted screens. Thus an investigation was conducted to experimentally determine the influence of the particle size and thickness on the screening process. The Response surface method was employed for modelling and analysis of the data. Experiments employing a central composite design were performed on a pilot-scale, rectangular-aperture, vibrating screen to examine the effects of the screening variables the mass recovery of flaky and non-flaky particles to the oversize product. The SAS statistics package was used to fit a second-order model to each response and to analyze the fitted surface to determine the optimum levels. The optimization associated with a dual response system was then considered. The results of this study should provide a basis for optimizing screening conditions to obtain maximum recovery of non-flaky particles to the screen oversize while minimizing the recovery of flaky particles, which should be of interest to the aggregate industries.

Jan 1, 1999

By J. Creamer

Pumping plays a major role across multiple process and facility applications in the mining world. Examples include: raw water supply, leach solutions, chemicals, dewatering, and mine drainage, and process water for metal recovery. Mining operations such as grinding, classifying, separating and concentrating minerals all have pumps at the heart of the operations Special purpose pumps such as dewatering, process water and slurry pumps are at the heart of many of these processes. Unfortunately the pumps themselves are often overlooked in terms of energy savings potential as they are often embedded into these sophisticated processes which are the ultimate operational focus.

Feb 23, 2014

By D. M. Steelman

Digital systems have been employed in industry as an aid in process evaluation and control for about 20 years. The earlier systems were quite simple and did little more than periodically scan a multitude of process variables, perhaps comparing them to alarm limits, and print out the results. As time passed, the needs of industry and the imagination of process engineers became more demanding. Rather than perform only alarm checking and logging, operating guides were generated to help the operator gain optimum performance from the process. Eventually, systems were entrusted with the job of manipulating the set points of the local analog control loops in a (DDAC) digitally directed analog control mode. Today digital systems are used to gather all-the process information, including both analog and digital variables; to make the necessary data manipulations; and to control the process end elements in a (DDC) direct digital control mode. During these years of transition from the very simplest systems to the complex systems of today, the demands upon the system engineer have been every increasing. The process engineer has required, among other things, more computational ability at high speeds, faster input and output rates, greater flexibility, better communication facilities (man-machine interface), (process oriented software), and finally, greater reliability at lower cost.

Jan 1, 1969

By J. A. Barrera-Godinez

Traditional batch flotation tests produce a limited number of data points from which to evaluate the kinetics of the process. In this research, continuous weighing of froth, from a modified circular flotation cell, using a computer/data acquisition system., has been coupled with chemical analyses from intermittent froth sampling. This combination has permitted the experimental data to be smoothed such that the flotation kinetic parameters could be determined with enhanced confidence. To demonstrate the procedure, a galena ore was floated to permit flotation kinetics to be investigated as a function of cell parameters. It was shown that the kinetic data of this lead flotation most closely correlated with the Huber-Panu three parameter model. In addition the results illustrated the effect of froth thickness, froth scraper rate and air flow rate on the cell performance, in terms of mass flow, grade and recovery.

Jan 1, 1990

By M. D. Monroe

Getting the best match between truck and haul road requires examination of many factors and their effect on the bottom line. Most mines use a bottom line measure based in some way on cost per ton of material moved. This measure focuses on the two components of truck haulage cost per ton: productivity (or performance) and operating cost. Productivity can be measured or predicted for specific tasks using either field measurement or modelling. Individual tasks can be combined to provide a larger scale, longer term net figure for total mine output. True cost is more difficult to capture as they are time and task oriented and can be influenced by a summation of factors over a truck lifetime. For example, "allocated" costs, such as owning (depreciation) and some repair costs, are spread over long periods of time. Other cost, such as fuel and tires can be tied more directly to certain tasks such as fuel and tire cost. This paper focuses on the more direct, task-oriented factors that affect truck productivity and cost.

Jan 1, 1992

By M. J. Klishis

This paper presents the findings of a study on roof bolters' hazard exposure. A "micro-analysis" of accident data was combined with ergonomic observations of roof bolter operators to categorize bolting-related injuries and a checklist was constructed. Bolting-related problems were identified as situations that could expose bolter operators to hazards. Approaches to avoid these situations were applied at six mining operations to evaluate specific problems in roof bolting operations. The re-search emphasized the importance of analyzing worker behaviors in the context of mining situations and equipment design problems that lead to human error accidents.

Jan 1, 1995