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By R. R. Sayers

Radioactivity, the property of radium that led to its isolation more than 30 years ago, is the characteristic that makes it of value in the treatment of disease. Tyler3 gives the following brief history of the investigation: The way to the discovery of radium was opened in 1895 by Rontgen, who found that the glow from a Crooke's tube contained penetrating rays, which .he called X rays. Prof. Henri Bequerel, while investigating the effect of various phosphor¬ escent substances, found that uranium salts produced photographic impressions even when enveloped with opaque substances. To Marie Sklovouski, a young Polish student, who later became Madame Curie, Professor Bacquerel delegated the task of learning how and why uranium possessed power to emit these peculiar rays, which he had proved to be electrical in character. Madam Curie, examining by electri¬ cal methods the radioactivity of a large number of minerals containing uranium and thorium, discovered that some specimens of pitchblende had about four times the activity of the metal uranium; that chalcolite, the crystallized phosphate of copper and uranium, was twice as active as uranium; that autunite, a phosphate of calcium and uranium, was quite as active as the same weight of pure uranium. In order to check these discoveries, she prepared chalcolite artificially, starting with pure products, but found that this artificial chalcolite had only the acti¬ vity represented by its composition, or, roughly, 40 per cent of the activity of uranium. This led to the conclusion that there was some element or substance in the residue from uranium minerals that possesses a high degree of activity. After an exhaustive chemical investigation of pitchblende from Joachimsthal, she found that this mineral contained not only uranium but also another radioactive sub¬ stance, to which she gave the name of polonium, in honor of her native land. Later in 1898, Monsieur and Madame Curie found still another element, which, when brought to a state of concentration, was several million times as active as uranium, and to this was given the name of radium. Debierne afterwards found a fifth radio¬ active substance, actinium; and in 1906 Boltwood isolated the metal ionium. Strict¬ ly pure radium chloride was first produced in 1902. The first radium was produced commercially from the uranium residues obtained from the mines of Joachimsthal, Bohemia. Tyler calls to attention that, as the ores were a government monopoly, search was begun at once for sources in other parts of the world. As a result, radium-containing ores have been found in about 10 countries.

Oct 1, 1932

By N. N. Ngoepe

Positron Emission particle tracking (PEPT), which makes use of a radioactively labeled tracer particle, a positron camera and a tracking algorithm has been shown to be a viable method for studying flow properties in both the pulp and froth phases of flotation cells. Detailed velocity measurements of 300-400 µm glass beads were extracted to assess turbulence from velocity fluctuations in a micro flotation cell. The effects of particle speed and orientation at the instant of attachment events were studied. A minimum speed of 0.16 m/s was needed for a collision to lead to attachment. The most attachment events happen when the particle is directly in line with the inlet tube at 90o.

Sep 1, 2012

By M. Mokgohloa, T. R. Stacey

Boring of tunnels and shafts in hard rock under high stress conditions is becoming more common as mines and tunnels are developed at greater depths. Under the high stress conditions, fracturing of the often-brittle rock occurs in the walls, backs, and ahead of advancing faces of excavations. Fracturing can have a significant impact on boring activities: sidewall spalling, which affects machine gripper capacity, and fractures can also develop in the rock ahead of the face, leading to blocky rock conditions, which may have a significant effect on machine excavation. Fracturing may develop dynamically, leading to rock bursts manifesting in the form of strain bursts, which can be hazardous and destructive. In brittle rock, fracturing is commonly extensional in nature. The focus of this paper is on fracturing in the face of the excavation. Examples of such fracturing behaviour are described briefly in the paper. Numerical analyses were carried out to predict the initiation of extension fractures and their orientations ahead of excavation surfaces, and the resulting formation of rock slabs/plates, and the stability of these plates. The results should be beneficial for the evaluation of the conditions prior to, and during boring operations.

Nov 27, 2024

By B. J. Scheiner

Electrooxidation of cinnabar mercury ores (HgS) was investigated as a means of providing an effective and economical hydrometallurgical technique for extraction of mercury from its ores, particularly those too low in grade to allow economical metal recovery by retorting or furnacing techniques. Oxidation was accomplished by electrolysis of ere slurried with brine. Cinnabar was dissolved by oxidation of the insoluble sulfide to soluble mercuric salts. The mercury ion in a brine solution forms a stable tetrachloro complex. Typical laboratory experiments required I to 7 hours of electrolysis at 35-percent pulp density in a brine solution that contained 4 to 20 weight-percent sodium chloride (NaCl). Power consumption ranged from 10 to 50 kwhr/ton of dry ore. Mercury extraction values between 90 and 99 percent were obtained with all of the ores investigated. Subsequent mercury recovery from leach solutions was readily accomplished by precipitation on zinc. Pilot mill experiments in a 100- to 200-lb/hr extraction plant are in progress to quantify power and reagent requirements, and extraction and recovery data obtained to date closely parallel those obtained in the laboratory.

Jan 1, 1970

By C. Musingwini, A. S. Nhleko, P. M. Muke

Open-pit mine planning includes the determination of a long-term open-pit mine production scheduling (OMPS) plan. The OMPS plan is generally a three-dimensional (3D) block extraction sequence that seeks to maximise the net present value (NPV) of future cash flows, while complying with technical and operational constraints. The OMPS problem is computationally complex because it involves the analysis of large datasets, while simultaneously incorporating both multiple hard and soft constraints. The OMPS problem has been solved using deterministic or exact approaches, heuristic, and metaheuristic models. When compared to heuristic and metaheuristic models, deterministic approaches tend to take much longer to solve the OMPS problem when the number of constraints increases. Therefore, this paper presents a metaheuristic model which utilises a genetic algorithm (GA) framework to solve the OMPS problem. The GA-based model was applied to the Newman1 and Zuck Small mining instances, which are publicly available from the online MineLib database. The NPVs for the OMPS plan generated using the GA-based model for the two case studies were compared to the best-known published MineLib solutions obtained using the TopoSort heuristic model at the time of this study. For the Newman1 instance the equivalent annual NPVs were approximately US$6.6 million for the GA-based solution and US$5.1 million for the TopoSort solution. For the Zuck Small mining instance, the equivalent annual NPVs were approximately US$99.8 million for the GA-based solution and US$102.5 mil for the TopoSort solution. These results show that the GA-based model produced comparable solutions to some of the best-known solutions, thus, indicating strong potential application of GA-based models to solve OMPS problems.

Sep 1, 2021

By W. R. Reed, J. P. Rider

"The National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) has recently developed a series of models utilizing computational fluid dynamics (CFD) to study airflows and respirable dust distribution associated with a medium-sized surface blasthole drill shroud with a dry dust collector system. CFD models were constructed in ANSYS FLUENT Version 15. Previously run experiments conducted in the NIOSH full-scale drill shroud laboratory were utilized to validate the models. The setup values in CFD models were calculated using experimental data obtained from the drill shroud laboratory and measurements of test material particle size. Subsequent simulation results were compared with the experimental data for test scenarios, including 0.14 m3/s (300 cfm) bailing airflow with 2:1, 3:1, and 4:1 dust collector-to-bailing airflow ratios and 0.24 m3/s (500 cfm) bailing airflow cases with 2:1, 3:1 and 4:1 dust collector-to-bailing airflow ratios. For the 2:1 and 3:1 ratios, results showed the calculated dust concentrations from the CFD models were within the 95% confidence intervals of the lab experimental dust concentrations. This paper describes the methodology used to develop the CFD models, to calculate the model dust input, and to validate the models based on experimental data. Problem regions were identified and revealed by the simulation of a dry dust collector system. The simulation results could be used for future development of dust control methods for a surface mine blasthole drill shroud. INTRODUCTION In surface mines, production drilling is an essential process in blasting which fractures the hard rock overburden for removal. Holes with a predetermined pattern, diameter, and depth are drilled into the overburden to introduce explosives. During the drilling process, considerable amounts of respirable dust are produced. Past research conducting area sampling at blasthole drills has documented time-weighted average respirable dust concentrations ranging from 8.68 to 95.15 mg/m3 [1] and 1.04 to 52.30 mg/m3 [2]. These high dust concentrations, which may contain silica, can lead to respirable dust over-exposures for the drill operator, drill helper, and other personnel in the vicinity. These over-exposures can lead to silicosis, an occupational lung disease that has no cure and is ultimately fatal. In order to prevent the development of silicosis to mine workers, the Mine Safety and Health Administration (MSHA) regulates the exposure to respirable dust. For metal/nonmetal (M/NM) mines, MSHA has adopted the threshold limit values recommended in 1973 by the American Conference of Governmental Industrial Hygienists (ACGIH) [3]. The total airborne dust standard is 10 mg/m3. However, if the sample contains greater than 1 percent quartz (the most common form of crystalline silica), a respirable dust standard is calculated with the following equation: Respirable dust standard = (10 mg/m3) / (% respirable quartz + 2)"

Jan 1, 2016

By Christopher B. Kapes

To reduce concentrate dewatering and drying costs, the Concentrator Division at Phelps Dodge Morenci, Inc. investigated available filtration technologies. Numerous methods were explored, including: drum, disk, belt, pressure, hyperbaric, and ceramic media filtration. An economic evaluation of the individual filtration technologies indicated the advantages of ceramic media filtration for Morenci concentrates. This paper discusses the technological development culminating in the first full scale application of ceramic media disk filters in North America. Low moisture contents are obtained at high production rates and greatly reduced operating costs.

Jan 1, 1994

What has happened to the basic coal industry during the past year? Has it been a better year for coal than 1961? What striking new developments have occurred in mining, preparation and utilization? Are there positive signs that production will go up? What has happened in the utility market, the metallurgical market and the export market? Is the controversial question of coal transportation nearer to a solution? What progress has research made for coal during the year? The answer to these and many other important questions are offered in the following review of the Coal Industry-1962.

Jan 2, 1963

The JORC Code contains a mandatory classification system for Mineral Resource and Ore Reserve estimates for public reporting. The classification is a statement of the Competent PersonÆs confidence in the estimate and an attempt to convey that confidence to the various users of the resource estimate. In general the classification process is either largely subjective, relying on the Competent PersonÆs experience, or relies on statistical measures derived from the estimation process, or is derived from an estimated level of confidence in the outcome. However, the statistical measures may not necessarily relate to the overall confidence in the resource or reserve which must take account of the confidence in the geological inputs to the estimation.In addition to the traditional deterministic interpretation and estimations adopted by geologists, semi-quantitative techniques are now available to improve the estimation of confidence while continuing to involve the Competent PersonÆs experience in the process. Methods for quantifying confidence in mineral resource estimates for advanced projects and operating mines have also been developed.Classification is undertaken primarily as a communication tool between the estimators and the other stakeholders in the process. A brief examination of the stakeholdersÆ requirements is included.

Sep 26, 2011

By A. House

Newmont Mining Corporation owns and operates the Phoenix Mine near Battle Mountain, Nevada, USA. The existing milling facility has operated since 2006. Following the startup of the milling operation, and coupled with the upswing in the copper market, Newmont realized that Phoenix needed a process option to treat lowgrade transition and oxide copper ores. This meant that potentially revenue generating ore was being mined as waste. With no system in place to treat the transition and oxide copper, work began to determine the most feasible approach. After evaluating multiple options, the flow sheet was set for a run-of-mine (ROM) heap leach pad and solvent extraction/electrowinning plant (L-SX/EW). This paper will discuss the synergies and challenges of developing a copper L-SX/EW plant at the Phoenix copper-gold mill.

Jan 1, 2010

By A. M. McKim, J. S. Ambler

"The iron ore of the Scully Mine is upgraded from 36 per cent Fe to 66 per cent Fe through single-stage crushing, wet autogenous milling, sizing by vibrating screens and two-stage spiral separation, followed by a process in which the concentrate is dried and then further improved by high-tension separators. The capacity of the concentrator is 17,000 long tons of concentrate per day. Discussion of the operation will recognize the special problems encountered in handling preponderantly fine ore, relate issues of interest regarding wear and review mechanical innovations found to be advantageous at Wabush. The modern trend toward big equipment, thoroughly instrumented, has been the theme of design. Effects on availability must be a consideration in this choice, and sectionalizing of circuits to minimize these consequences is as important as streamlined maintenance."

Jan 1, 1969

By W. R. Hardwick

This Information Circular describes the development of block-caving methods and practices by the Miami Copper Co. at the Miami mine in Gila County, Arizona. It is one of a series published by the Bureau of Mines on mining methods, practices, and costs in various mining districts of the United States. This report gives a history of the district and outlines early prospecting and exploration including methods of sampling and estimation of ore tonnage and value at the Miami mine. Early mining methods are described, particularly those that influenced developments in the caving method. Mine exploration, development, and operating methods for block caving are described with particular attention to those factors, physical, economic, engineering, and managerial that have improved efficiency in the mining operations over a long productive period. Extraction, ventilation, wage system, safety, water supply, power plant, and shop facilities are discussed. The last section gives a brief sumary of such costs as are available for publication.

Dec 1, 1964

By P Esteves, J L. Bechir, R Galery, C Senna, V Souto

The current moment experienced by the mineral industry is marked by a series of economic, social and environmental challenges. Among the main challenges, it is important to highlight the decreasing in ore grades with the gradual depletion of the existing deposits, the high volatility in international commodity prices and the operational inefficiencies in the mine, beneficiation, and metallurgical plants. In this context, mining companies are continuously looking for alternatives that minimize production costs and maximize overall production. In addition, recent tragedies involving tailings dam collapses in Brazil, reinforced the need for a more responsible, sustainable, and conscious mining, such as aiming the preservation and rehabilitation of the land environment. In this scenario, the Sensor-Based Sorting (SBS) technology is currently getting more space into the mining market. This separation technology aims the removal of gangue material in coarse particle size fractions, prior to comminution and concentration stages. As a consequence, the technology allows a smaller consumption of energy, water, chemical reagents and other inputs. Moreover, the sensor-based sorting is a dry processing technology and favors the reduction of fine material to be sent to the tailings. The aim of this paper is to provide information regarding the technical and economical evaluation of SBS technology applicability to a zinc silicate mining in Brazil. The project evaluation was performed in two stages: laboratory test work and the execution of a pilot plant. The execution of a pilot plant allowed the technology optimization, quantification of downstream process effects, such as a proper economic evaluation about the technology benefits. Keywords: Sensor-Based Sorting; Particle Sorting; Ore Sorting; Preconcentration; capital expenditure (CAPEX); operating expenditure (OPEX); zinc; comminution; dry processing.

Nov 10, 2020

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 Ron Ketterling

We will discuss electronic and paper record keeping, what works and what doesn’t. We’ll review record keeping in light of those five sub-committees: Audit, Awards, Constitution, Ethics and Planning. You’ll come away with concrete steps you can use to improve your record keeping processes

Feb 1, 2020

By James R. Arnold, John O. Marsden

Introduction Metallurgical accounting practices have been revolutionized over the past 15 years by the introduction of low cost personal computers and easy- to-use spreadsheet software. The Chimney Creek metallurgical accounting system takes full advantage of these advances. Data is provided by a PLC-based process control system, IBM data logging, operator logsheets and assay results from an automatatic plant sampling system. The data is organized and stored in an IBM PS/2 system using Lotus 123 and customized accounting programs to provide a comprehensive information management system. Metallurgical accounting for gold plants should ideally provide information for the following: a) Gold production accounting b) Day-to-day process control and operation c) Metallurgical evaluation and process optimization The Chimney Creek system provides all of these while overcoming specific accounting problems presented by SAG milling a coarse feed, grinding in cyanide and dump leaching run-of-mine material. Process description Gold Fields' Chimney Creek mine is located 47 miles northeast of Winnemucca, Nevada, at the northern end of the Osgood Mountains. Ore is processed by a combination of dump leaching and milling processes. The dump leach operation treats approximately 2.0 million tons per year of low grade ore (0.030 oz/ton). Run-of-mine ore is top dumped in 40 foot high pads. The use of three solution ponds for leaching enables an intermediate solution to be recirculated to the leach pad to reduce the pregnant solution flowrate and increase gold tenor of solution to the carbon-in-column (CIC) recovery circuit. Gold recovery is approximately 65% by this method. The milling process employs a SAG mill-ball mill grinding circuit to treat 900,000 tons per year at an average grade of 0.19 oz/ton. The ore is crushed to minus 12" in a jaw crusher prior to feeding the SAG mill. Cyanide is added to the grinding circuit to start gold dissolution as early as possible. After grinding, leaching of the ore is continued in a unique two-stage counter current decantation circuit 1 with 12 hours of leaching between stages . 85% of the soluble gold is recovered from the first stage thickener overflow in carbon columns (CIC). The second stage underflow is treated in a scavenger carbon-in-pulp (CIP) plant. Ultimate gold recovery is over 95%. Loaded carbon from both the dump leaching and milling processes is pressure stripped by hot cyanide solution and gold is recovered from the resulting solution by zinc precipitation. The precipitate is retorted for mercury removal and smelted into bullion. The plant flowsheet appears in Figure 1. Data collection Data for daily metallurgical accounting is obtained from three sources: a) Plant sampling b) Process control system c) Operator logsheets All of the data collection for metallurgical accounting is based around the 12-hour shift operating schedule. Sampling All critical sampling for gold production accounting is performed by automatic samplers (Figure 2). Heath & Sherwood two-stage sampling systems are used for sampling all slurry streams (cyclone overflow, CIP feed and CIP tails). The automatic sampler consists of a pneumatically operated primary sample cutter and a continuous rotary secondary splitter. The cyclone overflow and CIP tails are the most critical samples since these are used to calculate gold into and out of the plant on a shiftly basis. The CIP feed sample gives additional information concerning intermediate dissolution and recovery

Jan 1, 1990

By Alan A. Campoli

"Pumpable crib support for longwall gates and ventilation bleeder entries is becoming more prevalent in United States coal mines (Figure 1). The pumpable crib selection and spacing design has been greatly refined by the full-scale testing conducted at the National Institute for Occupational Safety and Health (NIOSH) Mine Roof Simulator. The peak load on 24-, 27-, 30-, and 36- inch diameter J-Cribs is, on average, 300, 400, 450, and 650 kips, respectively. Standard J-Cribs have useful deformation of approximately 8 inches. The maximum useful deformation can be extended to 18–20 inches with an exterior reinforcement layer or an interior double wall, for all four J-Crib diameters. J-Crib diameter is primarily limited by a maximum 4.5:1 height-to-diameter aspect ratio. Spacing is controlled by immediate roof stability, anticipated pillar deformation, and roof bolting practice. Approximately 500,000 J-Cribs have been successfully placed in 18 different United States longwall coal mines. The selection and spacing of the J-Crib utilized to date is summarized for each mine.IntroductionLongwall productivity and safety depend on ground stability in gate and ventilation bleeder entries. Numerous support technologies have been developed and employed in United States longwall mines since the 1990s to replace traditional wooden cribbing. Many, if not all, of these technologies have been evaluated at the NIOSH Pittsburgh Research Laboratory since the mid-1990s (Mucho, et al., 1999). The NIOSH Mine Roof Simulator has a 3,000-kip vertical load and 24-inch displacement capacity, which has facilitated in-depth analysis of complex multimaterial support technologies like the pumpable crib. The extreme cost and human exposure risk associated with modern longwall mining prevent the trial and error development that would have been required absent the Mine Roof Simulator research. As a direct result of this research, pumpable cribs are becoming a major component of the standing support industry, providing the peak capacity and extended deformation characteristics necessary for successful gate and bleeder support. Recent research by Zhang, et al. (2012) and others have defined the required performance characteristics."

Jan 1, 2015

By J. A. Finch

The metallurgical performance of a flotation cell is strongly influenced by the features of the bubble population, characterized by the gas dispersion properties, a collective term including bubble size, superficial gas velocity and gas holdup. It is required that gas be well distributed throughout the cell. Gas distribution is estimated here by simultaneous measurement of gas velocity (Jg) at different distances from the center (radial Jg mapping). This communication describes a technique to perform radial Jg mapping together with fundamentals for the interpretation of the data.

Jan 1, 2009

By Visitor Makiyi, Chris Batten

Poor coal recovery due to coal damage or loss caused by blasting can have a significant impact on a mining operation. Increasing coal recovery by reducing blast damage can provide a significant opportunity for coal mines to maximise their revenue and reduce their operating costs. This paper provides details on advanced drilling and blasting techniques used throughout the coal industry globally to prevent coal damage and movement during blasting. Typical coal loss and damage mechanisms are explained, along with how each of the applied techniques works to minimise the impact of each mechanism. Key requirements for a coal loss reduction program are detailed with typical design parameters used for each of the methods discussed. The positives and negatives of each method are also provided to enable comparisons and help determine suitability for a particular coal mining operation.

Jan 21, 2025

By Harmon E. Keyes

Many organizations, including the Bureau of Mines, have made intensive studies of the application of leaching methods to relatively small low-grade disseminated deposits of copper ores, containing both oxide and sulphide minerals. One of the principal difficulties has been to obtain a solvent that could be made at a low cost and would effectively dissolve the copper minerals. Another drawback has been the high initial cost of a plant and the refined type of mechanism ordinarily required by standard practice for carrying out the leaching cycle. The Bureau of Mines has attempted to develop a cheap and efficient solvent that would especially meet the requirements of smaller plants. (See Bibliography.) It has been known that dilute ferric sulphate-sulphuric acid solution is an excellent solvent for most copper minerals, such as chalcocite, bornite, and oxidized forms, but not for chalcopyrite and certain silicates. A method of producing this solution from sulphurous products and waste liquors was developed by the bureau and tried successfully on a test-plant scale at the Southwest Experiment Station in cooperation with the department of mining and metallurgy, University of Arizona, Tucson, Ariz. However, this work did not involve the actual leaching of ores with the solutions thus produced or the cyclic use of the iron solutions in the regenerator cell. Except for certain laboratory tests, in which known impurities were added, no data were available to show the effect on regeneration if accumulations of impurities were built up in the leaching circuit.

Jan 1, 1930