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By M. M. Moghaddam

Charge motion is of prime importance in the efficiency of comminution in tumbling mills. Since direct observation of charge shape and its motion in industrial mill are not possible, a combination of analytical and physical studies was used to determine charge trajectory. Software packages, which predict charge motion such as the GMT (Grinding Media Trajectory) only consider the outermost layer of charge (single ball) and ignore the interactions of grinding elements. In this research, the measured charge trajectory in a 1m-diameter mill with the transparent end, called model mill, was compared with that of the GMT. Four types of polyurethane rings were accurately machined to scale down the liners arrangements at two industrial mills. To explore various charge shapes and trajectories, the model mill was operated at 55, 70 and 85% of critical speed for five levels of mill filling (10, 15, 20, 25 and 30% by volume). The angular displacement of the toe, toe departure, shoulder and charge impact point were determined from the photographs taken from the model mill. New relationships to predict charge shape and charge impact points were introduced to modify the GMT results. The relationships were validated by the model mill using the new liner of the Sarcheshmeh copper complex SAG mill. The relative error of prediction was found to be 1.1%. The results indicated that when the lifter face angle increased from 7 to 30º, the distance between the charge impact point and the toe decreased from 52 to 31º for 25% filling. This meant increasing the probability of charge impacting the toe not the liner which favoured more efficient comminution practice. After converting AG mills to SAG mills on account of liner profile change, 31% increase in throughput (from 419 to 548 t/h) in addition to 4% decrease in the product size (from 516 to 496 µm) were realized which was a significant contribution in the plant performance improvement.

Sep 1, 2012

By Eun-young Kim

Electrogenerated chlorine leaching of waste printed circuit boards was investigated in hydrochloric acid solutions. The pulverized printed circuit board contained about 37.6% of metal component, in which copper was about 83.6%. The leaching rate of copper was greatly affected by current density and agitation speed. The leaching of copper up to 98% was achieved at 20 mA/cm2, 50?, 180 minutes, and 600 rpm in 1M HCl solution. Increasing agitation and lowering current density enhanced utilization efficiency of electrogenerated chlorine. Leaching of copper was suppressed at initial stage, while the minor metal elements, such as aluminum, lead, and tin, were dominantly leached out.

Jan 1, 2006

By Heinz Böni, Christian Ludwig, Bernhard Steubing, Uca Silva

"Chile will soon have to find solutions for dealing with rapidly growing quantities of Waste Electrical and Electronic Equipment (WEEE) due to its strong economy and fast increase of internet and communications technology usage. To support this process, the state of the Chilean recycling infrastructure as well as government, industry and consumer efforts to deal with ewaste were analyzed. Current e-waste quantities were assessed and future flows were predicted using a material flow analysis model. In this model computer hardware was used as tracer equipment for WEEE. Best available numbers indicate that today’s formal recycling infrastructure receives less than 3% of the annual quantities of computer waste. This study represents the most comprehensive analysis regarding e-waste in Chile, identifying relevant streams of e-waste and providing a basis for authorities and producers of electronic goods in order to take the necessary actions to establish an adequate recycling system.IntroductionSince 1991, Chile has experienced a period of strong economic growth. It is amongst the countries with the fastest development in the sector of Information and Communication Technologies (ICT) in Latin America and the number of people with access to ICT has been growing rapidly. The high growth rates of the computer market over the last years are representative for the ICT sector with the consequence that the generated quantities of electronic waste are increasing rapidly [1, 2].Waste Electrical and Electronic Equipment (WEEE) or e-waste is “any appliance using an electric power supply that has reached its end-of-life” as defined by the OECD [3]. Even though the overall waste management in Chile has improved much over the last decade, the issue of ewaste was hardly addressed. Due to the value of the materials contained in computer waste - such as precious metals, basic metals as copper or plastics - it may be assumed that an important quantity is already being recovered. This usually takes place on the informal market under questionable conditions for human health and the environment [1, 2, 4]."

Jan 1, 2008

By J. R. Shultz, R. J. Lambert

One of the present trends in the mining industry is the increased use of mining contractors. In the past, many project owners have utilized mining contractors for topsoil stripping or overburden removal, usually on a short-term or periodic basis. In recent years, mining contractors have not only removed the overburden, but mined the product as well. Why is this change occurring? A prevalent trend in the mining industry appears to be the outsourcing of non-core and non-strategic functions, allowing producers to focus more on areas of technical expertise where higher incremental value is added—that is the processing, refining, and marketing of the product. As capital allocation becomes more critical, this trend is likely to continue.

Jan 1, 2002

By F. Ikumapayi

In order to predict and minimize detrimental production problems due to the recycling of process water in sulfide ore processing, the influence of major species, calcium and sulfate in process water on sphalerite flotation was investigated through Hallimond tube flotation, zeta potential, diffuse reflectance Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements using sphalerite mineral sample. Assessment of process water species in flotation was done using deionized water, process water and simulated water containing calcium and sulfate ions in experiments. Hallimond flotation shows increased sphalerite float-ability in process water compared to deionized water, but no significant effect on the presence of calcium and sulfate ions in deionized water using isobutyl xanthate as a collector. The presence of calcium ions reduced the sphalerite?s negative zeta potential, while at higher concentrations, a charge reversal occurred, at about pH 11. FTIR and XPS studies revealed the presence of surface-oxidized sulfoxy and carbonate species on sphalerite at pH 11.5 in deionized water, process water and water containing calcium and sulfate ions. These surface species do not influence xanthate adsorption.

By John A. Breslin

The year 2010 will mark the 100th anniversary of the beginning of the research efforts by the U.S. government to improve the health and safety of miners working in the United States. This research began in 1910 with the establishment of the U.S. Bureau of Mines (the Bureau) and it has continued during the past 10 decades, even after the closure of the Bureau in 1996. The research on safer mining technology, formerly done by the Bureau, has now been combined with National Institute for Occupational Safety and Health (NIOSH) studies of miners? health to form a unified federal research program to improve the health and safety of miners. This article describes this research and places some of the accomplishments into perspective with other activities in the U.S. Mine Safety and Health Time Line (insert).

Jan 1, 2010

By R. Ramesh

Understanding the nature of coal surface heterogeneity is a prerequisite to accurate characterization and efficient control of coal surfaces. New techniques based on the centrifugal immersion of particles from the liquid/ vapor interface and film flotation have led to independent estimation of surface energy distributions in individual coal particles. Changes in the distribution of surface sites due to oxidation and polyacrylamide adsorption on coal are studied here using the above techniques. New information on -possible conformations of adsorbed polymers is also obtained.

Jan 1, 1989

By Gordon M. Miner

When I was originally invited to speak to this audience on the subject of the future supply of precious metals I was somewhat apprehensive and suggested that the Program Chairman select someone with more credentials. He declined and the results of our conversation gave me cause to reflect and recall the opportunities I have had over the years and how fortunate I have been to be associated with so many successful companies and knowledgeable people affiliated with the precious metals field. I discovered that since 1935, 1 have worked in or visited most of the gold and silver camps in the United States; have been a leaser of a gold mine in Mohave, California; have both lost and made money in the silver futures market; have worked for two of the greatest precious metals companies in the United States - Homestake Mining Company and Hecla Mining Company, have spent a considerable amount of time in precious metal related discussions with men like Don MacLaughlin, Paul Henshaw, Dick Stoehr, Abe Shoemaker, Bill Love, Phil Lindstrom, Simon Strauss, Herbert and Bunker Hunt and many others. It is those exposures and experiences that I draw onto discuss the subject at hand.

Jan 1, 1980

By S. Banisi, E. Arghavani, A. Akbari, Gh. A. Parsapour, S. Darvish Tafvizi

The new copper processing plant of the Sarcheshmeh copper complex consists of two parallel circuits. After a primary crushing, the ore is sent to a SAG mill and the product is further ground in a ball mill. The overflow of the hydrocyclones is fed to a flotation circuit which contains 8 rougher tank cells (RCS130), 3 cleaner cells (RCS50), 5 scavenger cells (RCS50) and a 4 x 12 m flotation column as recleaner. The circuit was initially designed to process a feed containing 0.8% Cu, but because of the ore type change, the feed grade decreased to 0.6% Cu. This resulted in a reduction of final concentrate grade and recovery from 28 and 85.5% to 24 and 84.4%, respectively. Based on the original design, the copper and silica recovery in the cleaner cells should be 69 and 55%, respectively, but these values increased to 85 and 75% because of a higher retention time. The rather high silica recovery (i.e., 75%) was found to be the main source of the lower final concentrate grade. In order to reduce the retention time of particles in the cleaner cell from 13.7 to 6.9 min, the rougher concentrates of two parallel circuits were fed to only one cleaner-scavenger and regrind circuit. This modification increased the cleaner and final concentrate grade from 15.1 and 24.5% to 17 and 26%, respectively. To prevent a possible reduction in the copper recovery, the froth depth in the scavenger cells was reduced. The overall outcome of the circuit modification was evaluated to be a 10% reduction in the energy consumption without any loss in the overall copper recovery.

Jan 1, 2016

By Roger L. Baer

Introduction Brief Review -SEC mission & history -Development of SEC mining disclosure guidelines -Principles of good public company ‘disclosure’ SEC staff views of alternative approaches to mining company disclosure -SME Resource & Reserve Committee – April 2003 Food for thought

Jan 1, 2003

By Yuanming Pan, Brett Rogers, Baoquan Hu, Gary Yeo, Christine Austman

The nature and distribution of radiation-induced defects (RIDs) in quartz from the Maw Zone, a yttrium- and rare-earth-element-enriched sandstone breccia complex exhibiting intense hydrothermal alteration, have been investigated by electron paramagnetic resonance (EPR) spectroscopy. EPR spectra show that detrital quartz in sandstone, from five diamond drill holes intersecting the Maw Zone and one above the crest of the so-called Quartzite Ridge, contain only background-level RIDs, indicating that Ubearing fluids were absent in this area. However, close to the sandstone-basement unconformity, in hole WR-194 immediately west of the Quartzite Ridge, the concentration of RIDs in detrital quartz is significantly above background but at least an order of magnitude lower than those at the Key Lake and McArthur River deposits. Widespread drusy quartz at the Maw Zone, which signifies intense hydrothermal alteration, is associated with hematite-, sulfide- and carbonate-bearing mineral assemblages, which exhibit complex crosscutting relationships. EPR spectra of drusy quartz in all three types of mineral assemblages are low in RIDs as well, supporting the EPR evidence that fluids at the Maw Zone did not carry significant U. These EPR results suggest that, in spite of intense hydrothermal alteration and favorable structural geology, the Maw Zone is unlikely to host any significant U mineralization. Moreover, this study shows that the EPR technique is potentially a useful exploration tool, capable of determining whether individual alteration zones in the Athabasca Basin were associated with U-bearing fluids or not.

Jan 1, 2013

By F T. Suorineni

Empirical methods are deeply rooted in geomechanics. This is a consequence of the recognised complexity of the nature of the rock mass. The usual assumptions of material continuity, homogeneity, isotropicity and linear elasticity often assumed for soil, concrete and steel are difficult to justify in a rock mass except for mathematical convenience. These assumptions form the bases for most mechanistic, analytical and numerical methods in geomechanics. Believers in empirical methods argue that the complexity of the rock mass and its interaction with structures developed in it is adequately accounted for in empirical methods, which compensate for our ignorance.Franklin (1993) defines empirical design as quantified judgement based on experience. He further states that empirical methods often prove ‘closer’ to the ‘truth’ than the apparently more precise predictions of theoretical analysis, adding that based on real data empirical methods provide a standard against which theoretical predictions are measured and can be judged. This paper takes a critical look at the common empirical methods in geomechanics – rock mass classification systems (Bieniawski, 1973; Barton, Lien and Lunde, 1974; Hoek, 1994a), Laubscher block caving design rules (Laubscher, 1994), the stability graph (Mathews et al, 1981), pillar design equations (Salamon and Munro, 1967; Hedley and Grant, 1972; and their derivatives), pillar design chart (Lunder and Pakalnis, 1997) and failure criteria (Hoek and Brown, 1980; and its derivatives). The common thread in the application of these methods is that in most cases they are often applied blindly without an understanding of the underlying assumptions and database limits. This paper emphasises that users of these methods need to know the underlying assumptions, database limits and inherent hidden risks that are often unmentionable for their satisfactory use. Finally, suggestions are provided for the efficient use of empirical methods and how they can be improved.CITATION:Suorineni, F T, 2014. Reflections on empirical methods in geomechanics – the unmentionables and hidden risks, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 143–156 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By W. F. Hazen

This paper describing the mining practices at a 100 per cent mechanized mine working the Pittsburgh or No. 8 coal bed in eastern Ohio is one of a series being prepared by the U. S. Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The purpose of assembling this data is to place before those interested in the mining industry the methods employed and the cost data on the items involved in the winning of the coal and its removal to the railroad car at the tipple. Mining costs are governed by the mining method used, which is selected for its adaptability to local natural physical conditions such as the nature and thickness of the coal, its dip, the character of the roof and floor, and the thickness of the overlying strata.

Jan 1, 1929

By S. E. Sankey

High anionic functionality acrylamide co-polymers and poly(sodium acrylate) are used as red mud flocculants in bauxite processing operations. These synthetic polymers are effectively displacing starch as the dominant polymer in red mud settling. The performance of these polymers is primarily dependent on the bauxite mineralogy, the alkalinity of the red mud slurry, and the anionic functionality and molecular size (viscosity) of the polymer. In this paper, the physical and chemical properties of the synthetic watersoluble polymers will be reviewed. The relationship between polymer structure and red mud slurry properties as they control polymer performance in settling red muds common to digester and washer circuits will be illustrated. The availability of polymers of varying functionality and viscosity will permit bauxite processors to make significant improvements in the economics of red mud disposal and valuable reagent recovery.

Jan 1, 1982

By R. J. Howarth, P. L. Llowenstein

The errors resulting from field sampling, sample preparation and analysis are investigated for drainage sediments derived from homogeneous sandstone, shale, limestone, basic igneous and granite lithologies as a background to a primary reconnaissance survey of England and Wales. Emission spectrographic analyses of approximately 350 samples for Al, Ca, Fe, K, Si, Ba, Co, Cr, Cu, Ga, Li, Mn, Ni, Pb, Sc, Sn, Sr and V and atomic absorption analyses for Cu, Ni, Mn, Co, Zn and Pb have been treated statistically. For routine broad-scale surveys analysis of the unground -80-mesh sediment fraction proves satisfactory. Sampling error between localities in a stream is shown to be less than spectrographic analytical error for many of the elements considered here, except where mineralisation (contamination) occurs, but exceeds the atomic absorption analytical errors in most cases. Unless it it critical to reduce the amount of between-site variability (having regard to analytical errors) in the regional survey, there appears to be no advantage in the use of a more sophisticated sampling technique. The utility of moving-average maps in reducing the width of the confidence belt around the regional 'geochemical surface', and thus compensating to some extent for the sampling errors, is also demonstrated.

Dec 1, 1971

By Brandon Buschmeier, Frederic Masse

"Inclusions are a type of ground improvement that provide an improvement of a soil mass by insertion of a material with better characteristics than the surrounding soils. There are primarily two types of inclusions: “Soft” inclusions which are constructed of granular material (Stone Columns, Rammed Aggregate Piers, VibroPiers...), and “rigid” inclusions which are constructed of grout inserted with or without pressure (VibroConcrete Columns, Controlled Modulus Columns, Soil Mixing Columns).While the central principle of the inclusions is similar (i.e., overall improvement of characteristics of the soil mass below the structure), the load transfer mechanism is radically different for each technique. Therefore, the applicable design methodology is specific to the type of inclusions and there exists no universal method of design which spans across all inclusions.This paper will present an in-depth comparison between the standard design methods used for “soft” granular-type inclusions (Priebe modified, Balaam & Booker, Goughnour & Bayuk...) and the methods used for “rigid” inclusions which mainly rely on finite element analysis. The paper will explain why the design for soft inclusion methods cannot be applied to rigid inclusions and vice-versa. Each design method will be reviewed in detail to better emphasize its limitations and advantages.Two case histories will also be presented; one for each type of inclusions in order to illustrate the concepts developed in the first part of the paper.1 INTRODUCTION1.1 GENERAL OVERVIEW OF GROUND IMPROVEMENT WITH INCLUSIONSThe use of ground improvement methods to provide the appropriate amount of foundation support is a growing and constantly evolving industry. Traditional structural foundation methods including ‘shallow’ and ‘deep’ foundations do not adequately address the wide range of settlement tolerances, soil conditions, and loading considerations inherent to each unique potential project. In some instances, ‘shallow’ foundation solutions are simply not feasible due to soil and loading constraints. Furthermore, ‘deep’ foundation solutions are used to ‘bridge’ the soft compressible soils, ensuring that the entirety of the load in the structure is transmitted through individual elements into competent layers below the ground surface (bedrock, dense residual soils). Highly concentrated structural loads are transferred into the individual elements by means of direct contact requiring the use of structurally rigid surficial components (structural slabs, grade beams, and pile caps).Ground improvement bridges the gap between these two traditional methods, offering adequate foundation support while using more costeffective techniques and design methodologies. Inclusions are a type of ground improvement used to provide a reinforcement of the soil mass through the vertical insertion of a material with better characteristics than the surrounding soils. Much like deep foundations, inclusions are installed through soil layers with high compressibility and/or low bearing capacity and terminated in a suitable bearing stratum. However, unlike deep foundations, ground improvement inclusions rely on a distribution of load between the soil and the inclusions. By doing so, some of the structural load is applied directly to the soil in a proportion equal to its bearing capacity and compressibility limits, while the rest of the load is shed into the vertical inclusions down to the bearing stratum. Load sharing is a critical aspect in the performance and design of the various ground improvement methods."

Jan 1, 2015

By Charles Camsell

At the Annual General Meeting of the Institute in 1924. I endeavoured to present the position held by the mineral industries in the commercial life of this country. The facts and figures were presented at that time in a detached way. Since then, however, I have made some attempt to analyze them in order to determine the causes for that position and to draw some conclusions as to the future of the mining industry. As everyone knows, our trade figures are very often used in political discussion, especially in discussion of tariff policy. It would be entirely out of order for me to say anything touching the tariff issue and I want to have it clearly understood that, in my opinion, the material I am about to present contains not a single statement or conclusion which anyone would be warranted in using as an argument for either a lower or a higher tariff or for tariff changes of any kind. As a starting point, let me re-state, very sketchily, Canada's general situation in external trade. In the last calendar year, 1924, we sold Canadian merchandise of all kinds to other countries to the value of $1,045,000,000 in round figures. Our purchases abroad reached about $893,000,000. Thus our sales exceeded our purchases by roughly $152,000,000. In other words, we had what is known as a 'favourable balance of trade' - one of the biggest favourable balances we have ever had in our history. The proceeds of our sales of Canadian products enabled us to meet the bills for all our purchases of foreign commodities and, in addition, placed a large surplus to our credit with which to offset our interest charges and other obligations abroad.

Jan 1, 1925

By E. H. Miller, E. J. Hall, M. J. Flak

It is well known that, with the exception of the so-called " niter-and-nails " method, all methods used for the fire-assay of salphide-ores,* especially those of iron, zinc, lead and copper, are very tedious and require the constant attention of the assayer. The objections to the niter-and-nails method are: The liability of the charge to boil over, due to the presence of the' niter; the low results in silver (uncorrected); and the frequently large discrepancy between the actual weight of the lead button and the calculated weight. In many cases the buttons are too small to collect all of the gold and silver contained in the sample, while in others they are too large for cupellation. It was thought that, if these objections to the niter method could be eliminated, it mould give a method for the crucible-assay of sulphide-ores, and especially the low-grade ores of zinc and copper, which would be superior to any method in use at the present time. The only similar methods of assay are those of Perkins,t Rhead and Sexton,$ and Mitchell. The method of Perkins requires too much litharge for it to be a commercial success; that of Rhead and Sexton, utilizing the prelimiilary assay we found to be the best;—the charge for the final assay, however, was modified by having borax-glass added to it; also, the oxidizing power of the niter mas determined by a charge which difters from either the preliminary or the

Jan 1, 1904

By V. Vekris

A diverse patent portfolio and an effective intellectual property strategy are vital in today’s small business world. Not only does a diverse patent portfolio enable a company to secure a monopoly within the market, it greatly increases the value of a company’s intangible assets and keeps competitors at bay. An overview of the patenting process as it pertains specifically to the materials science-related start-ups will be given, together with a summary of some general patenting strategies and a review of some patenting errors to be avoided, such as premature disclosure of the invention to the public. Additionally, a review of new “green technology” initiatives recently adopted by Patent Offices around the world is also provided. These initiatives are expected to greatly benefit patent applicants in the fields of metallurgy and mining, where research efforts are often directed to environmentally-friendly products and processes. INTRODUCTION Patents are playing an increasingly significant role in the business world. A diverse patent portfolio can enable a company to secure a monopoly within the market, which can provide a competitive advantage over competitors. At the same time, patent portfolio of any size can greatly contribute to the total value of a company’s intangible assets. As an example, Nortel entertained bids in 2011 for its portfolio of about 4000 patents, a large portion of which were directed to 3G- and 4G-mobile communication technologies. The portfolio was eventually sold for $4.5 billion to a consortium including Apple, EMC, Ericsson, Microsoft, Research in Motion, and Sony. Copper mining, and indeed the global mining industry as a whole, is facing challenges. Ore deposits are increasingly low grade, complex, and deeper in the ground, rendering copper mining operations more difficult and costly. Production costs are increasing. According to one study, the cost of producing copper has increased by an average of 10% per year since 2005 (Cantallopts, 2017). To illustrate, the cost of producing a pound of copper in 2005 was 90 cents, but had increased to 217 cents by 2014.

Jan 1, 2019

By C. D. Litton

When methods to prevent the occurrence of fire in underground mines fail, the next line of defense is to rapidly and reliably detect the developing fire, so that subsequent evacuation and control procedures can be safely and successfully implemented. To provide this capability requires an understanding of the operational principles of different types of fire sensors, their merits as well as their limitations, and performance characteristics of the monitoring systems that control and process sensor data; an understanding of how fires develop and the different types of fires that can occur, along with their characteristics and the hazards they present; an understanding of the impact of the mine environment and routine mining activities, not only in terms of these effects on fire sensors but also in terms of the impact of mine ventilation and mine geometry on fire growth, fire characteristics and the detection process. All of these factors are components of the technology of fire detection, and when insufficient knowledge of any of these components exists, the ability to implement adequate mine fire detection systems is diminished. Within the last decade, significant advances have been made in fire detection technology applicable to underground mines. These advances include not only the development of improved sensors and better monitoring systems, but also an expanded understanding of how to deploy sensors, set sensor alert/alarm levels, account for ventilation effects, etc. In addition, there has been an increase in our knowledge of the types of fires that occur, the types of combustibles involved, characteristic times for fire growth and development, the levels of heat, smoke and gas that are produced and the hazards that result. It is the intent of this paper to provide not an overview of current mine fire detection technology and, also, to present data obtained for some smoke sensors that have potential for use in underground mines. The paper will also discuss the data, information and resources that are currently available and seek to identify those areas most in need of further research and development.

Jan 1, 2011