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By M. Li, J. K. Thompson, A. S. Azman

Powerful mining systems typically generate high-level noise that can damage the hearing ability of miners. Engineering noise controls are the most desirable and effective control for overexposure to noise. However, the effects of these noise controls on the actual hearing status of workers are not easily measured. A tool that can provide guidance in assigning workers to jobs based on the noise levels to which they will be exposed is highly desirable. Therefore, the Pittsburgh Mining Research Division (PMRD) of the U.S. National Institute for Occupational Safety and Health (NIOSH) developed a tool to estimate in a systematic way the hearing loss due to occupational noise exposure and to evaluate the effectiveness of developed engineering controls. This computer program is based on the ISO 1999 standard and can be used to estimate the loss of hearing ability caused by occupational noise exposures. In this paper, the functionalities of this software are discussed and several case studies related to mining machinery are presented to demonstrate the functionalities of this software.

Jan 1, 2016

By F. Patisson

One of the major issues with multiparticle reactors is to handle their multiscale aspect. For modeling, it usually comes to coupling a reactor model (describing the phenomena at the macroscopic scale) with a so-called grain model (simulating the behavior of a single grain or a particle). An interesting approach proposed by H.Y. Sohn (1978) is to use the law of additive reaction times in order to calculate, approximately but analytically, the reaction rate of a particle in the reactor model. Its great advantage, compared to a numerical grain model, is to drastically reduce the computation time, particularly in the case of complex reactor models. This is the approach we retained for modeling the moving bed furnace, a counter-current gas-solid reactor used in the nuclear fuel-making route for producing uranium tetrafluoride from uranium trioxide. The numerical model we developed is 2-dimensional, steady-state and based on the finite volume method. It describes solid and gas flow, convective, conductive and radiative heat transfers, and six chemical reactions involved in the process. The law of additive reaction times is used to calculate analytically the rate of the three principal gas-solid reactions at every discrete point in the reactor. We have demonstrated the validity of this approach by comparing its results with those calculated from a numerical grain model. Also detailed in the paper are the main results of the moving bed furnace model itself and the possibilities of optimizing the process revealed by the calculations.

Jan 1, 2006

By J. E. Feddock

To succeed in today's competitive coal market, coal companies must continuously improve production and lower cost. However, the coal industry's historical management practices must change to remain viable? The practices of the current day efficient coal mine manager are reviewed and examined using W. Edwards Deming's definition of management. The statistical tools, including Pareto Charts, Control Charts and Scatter Diagrams, which identify the problems management must approach differently to increase productivity at a coal mine, are discussed.

Jan 1, 1993

By G. Deschênes

"In 2013, as the prices of precious metals dropped, investors moved their positions to equity markets for higher returns. As a result, the price of gold dropped further to below US$1200 per ounce, prompting additional substantial outflows from gold investments. In response to lagging gold prices, major gold producers initiated large asset write-downs and cost-cutting programmes. In 2015, this trend continues and gold mining stocks are close to lows not seen since the global financial crisis (GFC) of 2008. In the current economic climate many projects have marginal economics, and the number of projects that have competitive development and production costs is declining. A competitive edge is particularly important with the decreasing grades of orebodies, increasing complexity of the mineralogy, and increasingly demanding environmental constraints. In addition, higher cost producers seek to optimize their process t o reduce operating costs.This paper presents some highlights of three case studies on optimization of gold leaching strategies that improved the economics of brownfield projects. Processing of sulphide-bearing ores was optimized by using the synergy between cyanide, lead nitrate, and oxygen. The outcomes were significant reduction of retention times while maintaining or increasing gold extraction and reducing cyanide addition and effluent treatment costs. A stirred tank reactor experimental programme led to direct implementation of reliable leaching strategies from laboratory scale to production. This approach resulted in savings of $2.2 million to $15.2 million on the three brownfield projects discussed in this paper."

Jan 1, 2016

By H Arvidson, A Walker, N Pollock

Following the recent tailings tragedy in Brumadinho, the Investor Mining and Tailings Safety Initiative was formed representing institutional investors in the mining industry. This Initiative, led by The Church of England (CoE), requested data from 726 mining companies on each of their Tailings Storage Facilities (TSFs). What this exercise confirmed was that there was no public database of TSFs, and that there was a clear gap in tailings management systems within the disclosing companies. We present an approach using technology to support best practice TSF management, governance and disclosure which was originally submitted as part of University of Cambridge Post-graduate studies in Sustainability Leadership in January 2020. The aim of the paper is to discuss how technology could be used to deliver a Tailings Management Solution (TMS) that is aligned with the Global Industry Standard on Tailings Management (GISTM), and supports rigorous governance leading to disclosure. Subsequently the goals of the plan are aligned with that of the co-conveners of the GISTM (the International Council on Mining and Metals (ICMM), Principles for Responsible Investment (PRI) and United Nations Environment Program (UNEP)) which is to facilitate operators’ trajectory towards zero harm to people and the environment. Most of the focus to date around tailings management post Brumadinho has been on monitoring technologies, of which there are many. It is obviously important to acknowledge the critical role of monitoring technologies; however, our approach is agnostic to monitoring technologies and assumes that all of them are relevant. Our focus is on the data management, reporting and governance leading to disclosure of the information. Critical components of developing the TMS include adapting existing software products and solutions, recognising a system thinking approach is needed, strategic partnerships to deliver an accessible solution faster and more cost effectively, and, new ways of collaborating. The TMS should also accommodate relevant regional geotechnical codes and standards. The industry need for a TMS is well established and urgent, with significant pressure from regulators and civil society for the industry to address this significant issue.

Jul 1, 2021

By P. J. K Leeuw, E. Uludag, M. J. Nong

Efficient drill-and-blast performance is pivotal to the profitability of deep-level mines, where high operating costs and declining grades demand maximum throughput. This study investigated persistent fragmentation problems at a longhole stoping operation that suffered from simultaneous oversized rock blockages in 300 mm × 300 mm grizzlies and excessive fines. Fifty-one muckpile images from five blasted stopes were analysed with Split-Desktop. Although the overall F₈₀ was 287 mm, nominally suitable for the grizzly aperture, the Rosin- Rammler uniformity index of 0.80 revealed a highly inconsistent size distribution containing both boulders and fines. Existing drill patterns were then evaluated with the Aegis underground software, which showed negligible crack overlap at the toe owing to inadequate spacing and burden. Insufficient energy overlap between blastholes, particularly at the toe, was found to contribute to the coarse fragmentation, while excessive fines were attributed to the crushing and severely fractured zones of blastholes. Optimisation simulations demonstrated that an 89 mm blasthole diameter on a 2 m × 2 m pattern would overlap, aligning with Aegis requirements of balancing powder factor, break angle, and energy distribution. Implementing this revised pattern is expected to reduce secondary breaking, prevent ore-pass blockages, lower fines, and ultimately improve overall production efficiency. The methodology illustrates how integrated image analysis and modelling software can effectively diagnose and address fragmentation issues, particularly in underground longhole mining, where challenging blasting conditions require a balance between achieving optimal fragmentation and maintaining stope stability. This approach offers a cost-effective pathway to improving comminution performance in deeplevel mines.

Oct 2, 2025

By C. A. Rowland

Introduction Comminution efficiency, as measured by relating circuit performance to the consumption of energy and the time and money required, can be determined by the following comparisons: Theoretical efficiency: The theoretical efficiency is the actual energy consumed in a comminution machine compared to the theoretical energy required to perform the size reduction. Operating efficiency: The operating efficiency compares the operating work index of a comminution machine to the Bond work index of the ore, as determined from bench-scale crushing and grindability tests or pilot-plant tests. Economic efficiency: The economic efficiency is comparing income from production to predicted income. Key words: Comminution, Bond work index, Grinding, Crushing, Ball mills, Rod Mills. Theoretical efficiency In their book Process Engineering of Size Reduction - Ball Milling, Austin, Klimpel and Luckie (1984) stated that, "We have tried throughout this book to avoid the use of the term grinding efficiency because the degree of conversion of energy to useful size reduction is an ill-defined concept. In addition, the only efficiency, which is of real interest, is the meeting of product specifications at the minimum cost." The National Materials Advisory Board, National Re¬search Council (1981), in the abstract of a report titled "Comminution and Energy Consumption" stated that, "Up to 99% of the energy consumed in grinding these ores may be expended in the movement of machinery, with noise and heat the undesirable byproducts, thus leaving only 1% of the energy available for size reduction. Coupled with this is evidence that many of today's crushing and grinding techniques not only are antiquated but have little or no scientific base of understanding." Throughout the past 50-plus years, grinding efficiency has been referred to as being from 1 % to 10%. The measurable basis for these observations is difficult to establish, but they appear to be based on production performance compared to theoretical energy requirements for the work done. The theoretical energy requirements were determined from the energy required to break a single particle or a thin layer of monosized particles by compression or by a single impact from an impact-testing device. King, Tavaras and Middlemiss (1997), in a paper titled "Establishing the energy efficiency of a ball mill" described such a test. These batch single-breakage tests generally do not duplicate the continuous-breakage process in the comminution machinery used in ore concentrators. Operating efficiency The currently available crushers and grinding mills are fed at a controlled continuous flow rate, and they impart the breakage pattern needed to produce the desired size reduc¬tion. While theoretically inefficient, they are the most practical comminution machines available. The operation of this machinery is relatively simple and can be controlled with available control systems. The essential factors in determining the operating efficiency of comminution machines are energy, as consumed in the machinery, and the required energy, as determined from test work. Bond work indices, obtained from bench-scale or pilot-plant crushability and grindability tests are used in the following Bond equation (Bond, 1960) to determine the energy required to produce the required size reduction

Jan 1, 1999

By C. A. Rowland

Comminution efficiency can be expressed in three different ways. Theoretical Efficiency: actual energy consumed, in a comminution machine compared to the theoretical energy required to make the size reduction. Operating Efficiency: compares the operating work index, calculated from production comminution machinery operating data, to the Bond Work Index from bench scale comminution tests or calculated from pilot plant operating data. Economic Efficiency: income compared to planned income. Using the Bond Work Index and operating work index, this paper explains how to determine operating efficiency.

Jan 1, 1998

By D. Debasis, Christopher Mark, Gregory M. Molinda

The stability of any underground opening is, in large part, a function of the strength of the rock mass which surrounds it. The Coal Mine Roof Rating (CMRR) has been developed to quantify the defects in the rock mass and compile a strength value which can be used for engineering design. The CMRR has been applied to a number of ground stability problems, including chain pillar design, roof bolt selection, hazard assessment, intersection design, and numerical modeling. The CMRR procedure and some of these applications are described in this paper. The CMRR will soon be available in a Visual Basic computer program, allowing easy integration into exploration programs and standard roof fall assessments.

By Dan Preston, Shane Yanagisawa, Robert Marshall, Don Deere

Geotechnical Baseline Reports often estimate the number of cobbles that will be encountered in terms of volume or weight. These estimates are practically impossible to verify in the field. ClaroVia Holdings in conjunction with Frontier Kemper Constructors Inc. developed Digital Geologist 2.0 to classify and count cobbles discharged from an EPB TBM at the RSC7 project in Burbank, CA. The system worked by using two stereoscopic laser sensors with a global shutter to scan and count cobbles at 12 frames per second. Results of the effort are revealed along with lessons learned and paths for improvement.

Jun 13, 2023

By J. H. White

It is hypothesized that the Hotelling Valuation Principle (HVP) can determine the value of developed gold reserves using simple methods and easily obtained data. This paper reports the results of an empirical test of this hypothesis. Using publicly available data from North American gold companies, we obtained data for V, R, p, and c and ran a simple linear regression using equation (1.1) as the definition of the dependent and explanatory variables. By examining the value of the coefficients of the resulting regression equation, we can draw conclusion as to whether or not the HVP can be confident1y used as an estimator of the value of developed gold reserves.

Jan 1, 1995

By M. S. Prithvi

Over the decades, mine and mineral processing plant operations for the most part, have been found to have had adverse impacts on the environment. At the same time, mineral processing and mining operations produce mineral products that are indispensable to modern society. Thus, the sector has desirable and undesirable attributes simultaneously. The situation presents itself as a contradiction (i.e.) the mineral processing and mining operations are wanted by society, and at the same time unwanted by society. The existing methods of addressing the issues raised above have evidently not been very successful in reducing the opposition to new projects and to the related activities such as land acquisition. This paper attempts to show the relevance and applicability of TRIZ for addressing the issue. TRIZ, or Teoriya Rezheniya Isobretatelski Zadach, is a Russian acronym meaning Theory of Inventive Problem Solving. TRIZ is a powerful tool that can be usefully applied to resolve such contradictions, using resources usually available within the system of interest. Accordingly, this paper introduces the issue background, followed by an introduction to some key concepts of TRIZ such as the 40 principles, separation principles and directed evolution. The paper goes on to apply the 40 principles to two case studies. The results show that TRIZ could be a useful tool to generate potentially innovative and sustainable approaches. Its most appropriate position would be as a supplement to current decision-making procedures, and as a validation tool to review existing solutions for possible improvements. Keywords: minerals, environment, TRIZ, contradiction, resources

Sep 1, 2012

By C. Ciriello

Six Sigma methodology, as applied within Xstrata (formerly Falconbridge and Noranda), involves a disciplined approach to managing projects, solving problems, improving performance, and leveraging information. The four (4) cornerstones of Six Sigma are the use of Philosophy (customer driven, desire to improve and discipline), Metrics (measurement systems), Methodology (scientific method and sequence of deliverables), and Tools (such as statistics, change management, and root cause analysis). This paper will outline the general steps of the Six Sigma methodology and demonstrate how each phase directly applies to a real plant metallurgical project aimed at reducing nickel losses of the rougher flotation circuit at Raglan. The main concepts of Six Sigma are described, along with the specific challenges, successes, and deliverables related to the project. It is also the authors' aim to demystify the basic Six Sigma principles.

Jan 1, 2007

By M. P. Hay

"For a model to be successful it must address the concerns and needs of a target audience. Further, the model must demonstrate the same patterns of behaviour as the real system, and need only be complex enough to meet this objective. If the model is too complex it can become unusable to those who need it most.With this in mind, SUPASIM has been developed for the practical metallurgist requiring only laboratory flotation rate data as input. Some 35+ successful plant simulations have been completed since 1985. The approach of SUPASIM is to characterise an ore, organise information in an understandable way and add structure to the complex flotation situation and hence support the metallurgist to interpret the relationship between variables and optimise the flotation process.The paper describes the basis on which the model was developed and sets out to provide an insight into interpreting laboratory flotation kinetics and their physical meaning in a production plant and the influence floatable gangue has on float performance and plant design. A case study illustrates how the ratio of slow floating mineral to gangue can influence circuit design and improve recovery on a plant scale.INTRODUCTIONThere is an enormous amount of useful data in the results of a laboratory scale rate test. Each variable of fraction and rate, for mineral, metal and gangue has a physical meaning in the plant. The link between float kinetics and the plant in respect of recovery, grade, pulp density, pulp flowrate, residence time, number of stages of cleaning and circuit configuration has been established by the author in the process of developing SUPASIM."

Jan 1, 2005

By Yang Jun, Qu Mei, Zheng Yao-wu, Chi Li-yuan

Due to the necessity of the prediction of blasting seismic effect around strip mine bench blasting area, the paper provides a method to predict the blasting seismic effect by employing the superposition of seed waveform at different monitoring points. The method assumes that blasting vibration waveform per hole is similar to seed waveform at monitoring point. Therefore seismic wave consists of the superposition of the waves from all of blast holes. Firstly, via sensors multiple seed waveforms can be achieved at different distances from signature hole. Then, by using the given dose and the distance, the vibration waveform of a certain blast hole can be calculated by the corresponding seed waveforms. Finally, the initiation delay time interval per hole is added to the propagation time to the predicting point. The predictive waveform at the whole blasting area can be obtained by superimposing all of the single waveforms. Considering the vibration waveform of a single blast hole changes greatly with the distance, under different distances condition the seed wave employed to superimpose is achieved from the similar distance. The experiments demonstrate that based on the method the predictive vibration waveform and spectrum are basically consistent with monitoring results around near-field blast. Compared with single seed wave method, the superposition method of multiple seed wave is more reliable to predict the duration of blasting vibration, the peak particle velocity, dominant frequency and frequency distribution.

Jan 1, 2015

By Inc. Pile Dynamics, Daniel S. Belardo, Marcus Galvan, George Piscsalko

Soil nails are often utilized as a temporary or permanent earth retention technique for slope stabilization and for excavation retention for existing or new structures. Soils nails are generally advantageous as installation is relatively rapid and they can be installed beneath existing structures and where site access for equipment is limited. Due to the typically small cross-section of these elements, the inability to inspect the holes prior to grouting/concreting, and the various installation techniques utilized, quality control for assessing the integrity along the entire length is limited. Currently, quality assurance is conducted by load testing to verify the pull out capacity after installation. The load testing is typically done on a small percentage of the total number of soil nails. This paper will provide the results of a demonstration where the new Non-Destructive Test (NDT) method Thermal Integrity Profiling (TIP) was used to access the integrity of several soil nails along their entire lengths. This TIP method has been successfully used for several years to assess the integrity in drilled shafts and ACIP piles. The TIP method assesses the integrity across the entire cross-section and can identify regions where bulges, necks, and insufficient grout/concrete are present. TIP testing can also help assure that the contractor's installation methods are adequate and consistent for the intended design. For the project presented, instrumented Thermal Wire were affixed to the centered tension bars prior to placement in the excavated shafts. Temperature measurements were recorded from the hydration energy generated after grout/concrete placement, capturing the entire heating cycle. Manufactured defects were installed on the center bar at multiple locations. The results and conclusion will be discussed as well as recommendations for future use.

Jan 1, 2017

By Shadia J. Ikhmayies

The SnO2/CdS/CdTe thin film solar cells were fabricated on glass substrates by using the spray pyrolysis (SP) technique for the deposition of the SnO2 and CdS layers and vacuum evaporation for the CdTe layer. The transmittance curves were used to investigate the interdiffusion in the two interfacial regions SnO2/CdS and CdS/CdTe by taking the first derivative of the absorbance as a function of wavelength. The appearance of new bandgaps around the bandgaps of SnO2:F, CdS:In and CdTe layers is a strong evidence on the interdiffusion in the two interfacial regions and/or the formation of quantum dots.

Jan 1, 2010

By Bo Hyun Kim, Mark K. Larson

Researchers at the National Institute for Occupational Safety and Health have tested the finite element code, UT3PC, with LaModel to evaluate their results using know case studies. The purpose of the testing was to demonstrate the usefulness and limitations of these programs in evaluating mine layout design. Both of these software packages are simple to use and free for public download. Their use by mine engineers, along with other tools, such as empirical methods, can enhance the assessment of a mine layout design. LaModel can model mining layout on a mine scale or, at least, on a multiple-panel scale. However, this software has limitations in calibrating to conditions at many coal mines in the western United States. The UT3PC software models smaller parts of a mine and is used to evaluate the design of pillars, shafts, or drifts; but the software calculates all components of the stress tensor and provides stresses, displacements, and safety factors throughout the model volume. The two codes are used to evaluate design of one known case, and UT3PC is used to evaluate another case. The results and approaches demonstrated in the testing are intended to aid mine engineers in evaluating site-specific problems and to show that these tools can provide useful information to the mine engineer in evaluating mine layout design.

Jul 1, 2023

By A. B. Cecala

It has long been known that ventilation is a cost-effective method to lower respirable dust concentrations in all types of mining applications. The National Institute for Occupational Safety and Health has been working on a number of different research techniques that use ventilation as a critical component to lower respirable dust levels at surface and metal/nonmetal operations in the United States. This article presents five such research efforts. The first research area discusses how improving the ventilation flow patterns in an iron ore mill facility lowered respirable dust concentrations by 31 pct throughout the primary grinding area. The second research area examines how respirable dust levels were lowered at a dimensional stone shop by using air cleaning units suspended from the ceiling. A third area discusses how improvements in ventilation at underground limestone mines lowered respirable dust concentrations. The fourth area examines how improvements in dust filtration and pressurization systems significantly impacted the air quality in enclosed cabs of surface mining equipment. The last area presents a newly developed clothes cleaning technique. This technique uses an air spray manifold to blow dust from a worker?s clothing in an enclosed booth, which confines the dust for capture and removal by a baghouse dust collector. These research areas represent an array of different control technologies to lower respirable dust concentrations. Ventilation is an integral part of these control technologies.

Jan 1, 2006

By Hugh McMillan

To protect the water supply for the Metropolitan Chicago area, the Illinois legislature, in 1889, created the Metropolitan Sanitary District of Greater Chicago. To insure the quality of the water supply, the Sanitary District collected and diverted the wastes of 750,000 people away from Lake Michigan. Today, the Sanitary District collects and treats the wastes from a domestic population of 5 ¼ million people and an industrial waste load equivalent to 4 ¼ million people. The District serves Chicago and 120 other cities and suburbs in an 858 square mile area. An average of 1300 million gallons of wastewater is treated each day, producing as a by- product about 700 dry tons of solids which contains more than $10,000 worth of plant nutrients when equated to the value of commercial fertilizer purchased in the retail market. The Sanitary District considered several alternatives to past methods for disposing of these solids, and chose land application as a technique to utilize the solids produced by the wastewater treatment process in a beneficial manner.

Jan 1, 1973