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By K. Biswas

For the pillars, which have been standing long after mining, the stability depends much on the weathering action in the presence of mine moisture. From the field observations, it has been found that this weathering action becomes critical in terms of pillar stability if the coal seam contains partings or binders in it. The weathering action degrades both the partings and coal in terms of their load bearing capacity as the mine moisture penetrates into them. This paper investigates the effect of weathering action on coal and partings in the laboratory. In the field, the strength profile in the coal and the partings and the effect of time (in terms of the pillar age) on them have been studied by using borehole penetrometer. In this paper, an attempt has also been made to establish formulae for time dependent strength of coal and partings.

Jan 1, 1997

By T. Eisele, T. Weldum, G. Rajala, H. Walqu, S. Kawatra

The throughput and energy efficiency of comminution circuits is reduced when ore characteristics change, causing bottlenecks in some portions of the circuit while leaving excess capacity in others. The results of analysis of three years of daily grinding circuit operating data for a full-scale plant has shown that the location of bottle-necks in the circuit will change depending on the nature of the feed ore. The circuit tends to be limited by the primary mill capacity when the ore hardness increases, and limited by the secondary mill capacity with softer ores. Two methods are considered for shifting load in the circuit to relieve bottlenecks by taking advantage of excess capacity in other parts of the circuit: 1) Addition of supplemental comminution operations, such as high-pressure grinding rolls, to process specific size fractions that are not handled efficiently by the primary mill; and 2) Use of screens to shift grinding load upstream from the secondary mills back to the primary mills. In the case of the plant examined in this study, it was found that 58% of the time there was sufficient excess capacity in the primary mills that the throughput of the circuit could have been increased by using screens to shift the grinding load from the secondary mills to the primary mills.

Jan 1, 2004

By Erik Westman, Benjamin Mirabile

"Ongoing research is being conducted to evaluate secondary support performance in longwall ventilation entries. In a three-entry longwall gateroad, secondary supports are applied in the #2 entry to maintain a functional airway for the entirety of second panel mining. This airway represents a pathway for contaminated mine air to travel from the longwall tailgate to the mine bleeder system. The ground response curve concept may be used as a design basis for selection of appropriate secondary support in these ventilation entries. Two types of secondary supports are monitored for load and convergence in this project. These monitored supports are pumpable crib supports and interlocking wood crib supports. To evaluate the effect of support density, two installation patterns are monitored for each support type. Both a single-row, protected airway pattern and double-row, full entry support pattern are monitored for each support type. Load and displacement data is collected for all support patterns as second panel mining retreats past instrumentation sites. Data is collected for approximately 200-feet inby the second panel face or as long as safely possible. Load and convergence data collected will be used to calibrate numerical models that will simulate ground response curves for the #2 entry inby the second panel face.INTRODUCTIONWhen a bleeder ventilation system is used, the #2 entry of a three-entry longwall gateroad system is designed to function as a pathway for contaminated air from a longwall face to the bleeder system during second panel mining. The #2 entry is subject to substantial ground movement and loading during its function as an air course because it is a single entry between two longwall gobs. Secondary support is regularly applied in this entry to maintain air course functionality during second panel mining.Research on performance and design of secondary supports has been conducted extensively over the last 30 years (Barczak and Gearhart, 1993; Barczak and Gearhart, 1994; Mucho, Barczak, and Dolinar, 1999). This research has focused heavily on the application of secondary support in longwall tailgate, with little research on the application of secondary support in bleeders or other ventilation entries (Mirabile and Westman, 2018). Secondary supports in #2 entry are likely to experience similar loading and ground movement as those applied in the tailgate entry. However, the designed lifespan of the mine entry and the definition of acceptable ground conditions differs from mine entries where more extensive research has been conducted."

Jan 1, 2019

From a gathering storm of climate change based legislation that could potentially overwhelm the mining industry, to the nuts and bolts of mineral processing and just about everything in between, about 100 mining and mineral processing professionals heard it at all at the 60th annual Colorado MPD Meeting April 22-24 at the Broadmoor in Colorado Springs, CO. With a sweeping agenda under the banner ?What in the world is new in mining and metallurgy? attendees were treated to four sessions and 21 presentations that covered the range of mining industry issues. Bill Reid, president, chief executive officer and director of Gold Resources Corp., spoke about his company?s El Aquila gold project in Mexico. With five projects in Mexico, Gold Resources Corps. is aiming to become a low-cost gold and silver producer. Its flagship property, the El Aguila gold project, is a high-grade gold and silver property with significant base metal credits of copper, lead and zinc. Production of the El Aguila project was targeted for mid-2009. Reid said that three high-grade deposits have been discovered at the El Aguila project. They include the high-grade ?manto? style El Aguila openpit deposit, the El Aire high-grade polyme-tallic vein system, which is underground, and the underground La Arista high-grade polymetallic vein system. The project is located 120 km (75 miles) south-east of the capital city of Oaxaca, Mexico. Reid said the property has yielded several exceptional gold and silver surface samples, including a 36-g/t (1.1 oz/st) gold sample and a 3,100-g/t (90 oz/st) silver sample. Other properties that Gold Resource Corp. has are:

Jul 1, 2010

By Ahmed Alghamdi, Salem AlGharbi, Aisha AlHarbi, Owain Morton, Norah AlMuhaisen

This paper addresses the challenges in optimizing the phosphate flotation process, specifically focusing on the variability in P2O5 recovery. An artificial intelligence (AI) driven Flotation Prediction Model was developed to accurately forecast P2O5 grades. Leveraging real-time data from various operational sources, the model provides insights into how operators can opstimize key flotation parameters to enhance product quality and recovery rates. The results demonstrate the effectiveness of AI predictive modeling in addressing operational variability, marking a crucial step toward intelligent operations in the phosphate flotation process.

Feb 1, 2025

By R. Woods, O. A. Kiehn, C. A. Born, F. N. Bender

Development of the flotation reagent scheme at Climax Molybdenum Company's mine at Climax Colorado is reviewed. Features of the mineralogy, milling practice and background of reagent changes are outlined. Special attention is given to the hitherto unpublished details of the application of depressants for copper and lead impurities. The present rougher flotation reagent scheme utilizes a neutral hydrocarbon oil, low in unsaturates and wax, as collector with a sulfated coconut oil emulsifier and pine oil frother. Lime and sodium silicate are used as rougher conditioning and slime dispersant agents. Chalcopyrite and galena impurities are de- pressed in both rougher and cleaner plants by stage addition of Nokes reagent and sodium cyanide to yield a metallurgical grade molybdenite concentrate containing greater than 90% molybdenite and less than 0.5%, 0.1% and 0.05% iron, copper and lead impurities, respectively.

Jan 1, 1976

By R. Schlüter

"The global mining industry is facing increasing challenges in terms of geological, technological and social aspects. Potential exploi-tation of deposits shows a tendency to increasing depth with complex ores and decreasing grades. A promising approach to deal with these constrains is by applying alternative extraction methods like (bio-)hydrometallurgy as in-situ leaching (ISL) technology. The Bergakademie Freiberg University of Mining and Technology established the “Biohydrometallurgical Center for strategic Elements” (BHMZ) to foster the interdisciplinary research along the entire biohy-drometallurgical process chain to extract indium from sulfide ores. The involved Department of Underground Mining Methods deals with the design and implementation of a pilot-scale underground testing facility for microbial in-situ stope leaching in its “Research and Educational Mine”. This paper discusses the potential of in-situ bioleaching under technological aspects. In addition, different conditioning approaches based on hydraulic and explosive methods for enhanced permeability in the formation are introduced and the gathered data will be presened. INTRODUCTION A reliable, substantial and sustainable supply of raw materials is of crucial importance for any industrialized country. This dependency applies to “strategic elements” including rare earth elements (REEs), platinum group metals (PGMs) as well as a variety of other metals like indium and germanium which are needed for high-tech industry and products such as electric and electronic devices, fibre optics and laser technology (Barakos et al., 2016; European Commission, 2010). Due to the economic growth of the BRIC-countries (Brazil, Russia, India, China), the resource policy of China as well as the volatile world mar-ket prices of different metals the availability of these critical raw materi-als and therefore the dependency of the high-tech producing countries has become increasingly important (Barakos et al, 2016). Adequate supply is often affected by the increasing depth of de-posits, lower metal concentrations and more complex ore mineralogy. In addition, mining activities are increasingly restricted by their envi-ronmental and social impact and footprints. As a consequence, con-ventional mining and processing methods are limited by high energy consumption and technical constraints."

Jan 1, 2018

By W. Zitz

Incorporation of heat exchangers into drilled shaft foundations is a novel approach to both improve the energy efficiency of building heat pump systems and provide necessary structural support using the same construction materials. In an effort to quantify the structural and heat exchange performance of deep foundations used as ground-source heat pumps, two instrumented test foundations were constructed as part of a new construction project in Denver, CO. They will be integrated into the conventional ground-source heat pump system for the building. This paper focuses on the lessons learned from the construction process for these energy foundations.

Jan 1, 2011

By J. R. Sims

Gold assays from production blastholes in the Mercur Hill Pit were used to delineate known ore zones and to determine how well previous exploration drilling defined these zones. The most important factors causing inadequate ore zone definition were: 1) inappropriate location of drill holes relative to the ore zones, 2) presence of stopes from previous mining, 3) sampling and assaying errors, and 4) smoothing of the ore zone boundaries during ore reserve estimation. Infill drilling strategies were evaluated to determine the efficiency with which a given drill pattern defined the known ore zones. A drilling strategy was developed which improved ore zone delineation when compared to techniques which maintained uniform drill spacing.

Jan 1, 1992

By Dean E. Albon

In the late 1940's and early 50's in southern Illinois, the usual open pit blasting in the coal field consisted of one or two rows of churn drilled vertical holes being shot with instant electric blasting caps. The entire shot detonated at one rime. In southern Indiana and Ohio most mines were drilling horizontal holes and they too were primed with instant EB caps. During the ten years from 1355 through 1965 many changes occurred in drilling and blasting methods. The churn drill in southern Illinois and the horizontal drill in Indiana and Ohio were replaced by the rotary vertical drill. The ammonia dynamites and liquid oxygen explosives were replaced by ANFO. The elctric blasting cap in the hole was replaced by a detonating cord down line and detonating cord trunk lines made the connections between holes and rows of holes. Host open pit mining was in areas far enough from town that the noise and vibration from blasting was, if not ignored, at least tolerated. During the 1960's open pit mining expanded to account for nearly 50% of the coal produced. Mines came closer to town and towns expanded along the highways with suburban homes and mobile homes. The mines began receiving complaints about the noise and vibrations from blasting operations.

Jan 1, 1976

By W. K. Utt, C. C. Woodward, W. L. Howie, G. G. Miller

The process of roof drilling and bolting is one of the most dangerous jobs in underground mining. In the United States, roof drilling and bolting results in about 1,000 accidents with injuries each year. Researchers, from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are studying the feasibility of using a drill-monitoring system to estimate the strength of successive layers of rock and assess the integrity of a mine roof. Such a system would allow roof drill operators to be warned when a weak layer is being drilled. Using measurements taken during drilling, a neural network can classify mine roof strata in terms of relative strength. The concept has been proven in principle. This research project was undertaken to increase the safety of underground miners, especially those involved in roof bolting. The system should be applicable to the mobile drills now used in underground mines, and the system would likely find wider application as well.

Jan 1, 2003

By K. Deaton

"INTRODUCTION A packaged cooling system is being developed for refuge alternatives (RAs) that meets MSHA qualification guidelines for deployment in coal mines. This system will allow full occupancy ratings of deployed Refuge Alternatives (RAs) to be maintained by keeping the apparent temperature inside the RA from exceeding 95°F. Research investigations sponsored by NIOSH have shown that heat buildup caused by occupants in mobile RAs will result in apparent temperatures that exceed the 95°F limit established in 30 CFR 7.504. Figure 1 shows the temperature rise in an inflatable RA having an occupancy rating of 23 people at an 81°F mine air temperature. This plot shows the need for either heat mitigation or occupancy derating in warmer mines. The RAECS will be designed to provide enough heat mitigation to eliminate occupancy derating due to heat buildup over the 96 hour refuge period.This paper describes testing of a prototype cooling system that uses proven vapor compression technology powered by batteries to keep the RA interior below the 95° limit for a minimum of 96 hours. Testing of this prototype cooling system was conducted in December of 2015 and January of 2016 at the NIOSH test mine in Bruceton, PA. December testing was conducted at the prevailing mine ambient temperature – approximately 60°F. The January testing was done with the mine ambient temperature in the immediate vicinity of the RA artificially elevated to 85°F. Realistic heat gain from RA occupants was provided by human simulators developed by NIOSH. These simulators add sensible heat corresponding to human metabolic processes and latent heat generated by respiration and perspiration. Heat generated by CO2 scrubbers was also added. Results of cooling system performance using these simulated loads at the two ambient conditions are described. A comparison of the apparent temperature in the RA using two different control techniques is also presented. This work documents the ability of the cooling system to meet the established apparent temperature limit at the full occupancy rating of a six person RA. A new cooling system intended for use with existing RA deployments and having greater cooling capacity is currently in development and will be described."

Jan 1, 2017

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 Kim McKnight

Dupont has successfully incorporated a Floatex Density Separator into its wet-gravity operations for the recovery of zircon from titanium tailings. Results indicate that the Floatex achieved a zircon recovery of approximately 95% while rejecting similar amounts of quartz and other gangue minerals. Additionally, a unit capacity approaching 16 tonnes/hr/m2 was achieved. Results also show that the alumino-silicates can be separated into other product streams that will further improve process economics and minimize waste material. The improved plant feed grade provided by the Floatex has allowed for either an increase in overall plant capacity and/or final product grade. This paper will present the findings from the in-plant study.

Jan 1, 1996

By Rami Abousleiman, Gabriel Walton, Sankhaneel Sinha

"Although conventional coal mine designs are conservative regarding pillar strength, local failures such as roof-falls and pillar bursts still affect mine safety and operations. Previous studies have identified that discontinuous, layered roof materials have some self-supporting capacity. This research is a preliminary step towards understanding these mechanics in coal-measure rocks. Although others have considered broad conceptual models and simplified analogs for mine roof behavior, this study presents a unique numerical model that more completely represents in-situ roof conditions. The discrete element method (DEM) is utilized to conduct a parametric analysis considering a range of in-situ stress ratios, material properties, and joint networks to determine the parameters controlling the stability of single-entries modeled in two-dimensions. Model results are compared to empirical observations of roof-support effectiveness (ARBS) in the context of the coal mine roof rating (CMRR) system. Results such as immediate roof displacement, overall stability, and statistical relationships between model parameters and outcomes are presented herein. Potential practical applications of this line of research include: (1) roof-support optimization for a range of coal-measure rocks, (2) establishment of a relationship between roof stability and pillar stress, and (3) determination of which parameters are most critical to roof stability and therefore require concentrated evaluation.INTRODUCTIONRecent studies on pillar design have suggested that the assumptions utilized in traditional methods such as tributary area theory (TAT) (i.e. overburden has no self-supporting capacity, infinite pillar array, and CHILE material properties) are invalid in many geo-mining conditions (Esterhuizen, Mark, and Murphy, 2010; Frith and Reed, 2017). Although TAT is conservative with respect to pillar loading, and mine fatalities have steadily decreased since 1990, roof-falls and pillar bursts still occur and injure hundreds of miners per year (Mark, Pappas, and Barczak, 2011). Even though large-scale global mine failure has not occurred in a US coal mine since 2007, the mechanics of global and local stability as governed by the relationship between geologic parameters, mine geometry, and engineering design are still not well-constrained.Numerical methods are a highly effective tool that can be used to gain further insight into these relationships. When using such an approach, calibration to existing empirical relationships is imperative to ensure that numerical model results are realistic. In this study, we utilize the discrete element method (DEM) approach in Itasca’s Universal Distinct Element Code (UDEC v. 6.0) (Itasca, 2010).DEM accounts for explicit separation and contact of individual deformable blocks (Jing, 2003) and captures how discontinuities can affect system behavior. Discontinuous and anisotropic rockmass properties are typical features in coal-measure rock which contain various horizontal (bedding) and sub-vertical (joints) fractures depending on their depositional environment, diagenesis, and historic and current stress states."

Jan 1, 2019

By John C. Nixon

In 1959, The Australasian Institute of Mining and Metallurgy (Aus. I.M.M.) was asked by the Federal Government of Australia and the State Government of South Australia to join in the formation and management of a new contract research organization which was subsequently named The Australian Mineral Development Laboratories (Arndel) ? This body was formerly the Research and Development Branch of the South Australian Department of Mines which had been set up to develop the Radium Hill uranium deposit. It had then gone into contract R&D and the State felt that it would be more appropriate for the Branch to become a separate national organization. The Aus. I.M.M. decided that a professional institute could not participate directly in Arndel and, as there was no other suitable industry group to do so, it formed the. Australian Mineral Industries Research Association Limited (AMIRA). AMIRA held its first Annual General Meeting in September 1959 when the first Council was elected and the Memorandum and Articles of Association were adopted. The initial task of AMIRA was to raise guarantees of work or cash from its members to underwrite Arndel for the first five years of operation. The Federal and State Governments also provided guarantees and Arndel commenced operations in January 1960.

Jan 1, 1977

By P. Somasundaran, Bruno Lartiges

Two different groups of mechanisms have been considered in the past to explain the effects of chemical additives on grinding. While one group of explanations is based upon alterations of surface and mechanical properties of the individual particles, the other group depends mainly on the arrangement of particles and their flow in suspensions. In this paper some of the past work on grinding aids is reviewed and attrition grinding of a commercially important ceramic material, zirconia (stabilized with yttria) with polyaaylic acid as grinding aid, is studied in order to determine the effect of the aid on the ground product itself. It was observed that even though polyaaylic acid did cause a drastic decrease in the viscosity of the pulp, it did not have any major effect on the grinding of zirconia at least up to 2000 ppm and only minor detrimental effect above it. Importantly, complexation by the polymer was found to cause extraction of yttrium into solution with possibly significant changes in the surface chemical composition of the product.

Jan 1, 1992

By F. F. Aplan

The material known as coal has a highly variable composition. As a consequence, coals show a great variation in their physical and chemical properties as a function of coal rank. The situation is further complicated because the preparation engineer must deal with raw coal, as mined. This is an assemblage of coal, upwards of 30% mineral matter and, typically, several percent pyrite. The kind and amount of the mineral constituents is also highly variable from source to source. A knowledge of coal rank and source location, and the kind and amount of associated impurities, is the first step in evaluating the response of a raw coal to preparation procedures. The raw coal must first be characterized before information from one source can be extrapolated to that of another.

Jan 1, 1988

By Michael Francis, Chris Darton

More than 55 km of tunnels have been constructed by TBM in the last 12 years to refurbish and upgrade the high voltage cable network in London. These include a tunnel of 20km length using EPBM machines in both clay and granular soils. Route selection was made with reference to subsurface structures, existing ground conditions, using suitable shaft locations addressing environmental concerns. The complex interfaces to manage included obtaining of consents to the coordination of multiple suppliers. The paper describes how all these challenges have been met successfully and how technology has been employed to provide for safe construction and operation in the congested urban environment.

Jan 1, 2003

By Jeffery L. Kohler

The research and development of a pattern recognition system which can predict incipient failures and safety hazards in the mine power network is described. An examination of mine electrical safety hazards revealed they are often related to the electrical equipment down-time experienced on mine sections. Based on this, a method is proposed that can improve both production and safety, without compromising either. Equipment failure modes are examined to illustrate how the ultimate failure can be predicted for enough in advance to allow a convenient and safe repair, followed by a discussion of actual monitoring system performance. Finally, the paper is concluded by projections of the system's utility to industry.

Jan 1, 1977