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By D. J. Barratt

The application of autogenous and semi-autogenous grinding circuits in recent years has contributed toward substantial savings in capital and operating costs compared to conventional circuits, particularly for large scale copper and molybdenum operations. Such savings have been realized from the deletion of operating, maintenance, equipment purchase and substantial civil/structural costs associated with secondary-/tertiary crushing and screening, fine ore storage and conveying. In spite of the downturn in the copper- moly industry in North America, there is still an interest in autogenous and semi-autogenous grincting for copper-zinc, gold and silver ores and in the overseas market. Both single-stage and two-stage circuits are in operation. Primary circuits operate autogenously or semi-autogenously in either open or closed-circuit. Critical sizes are extracted and crushed for recycle in some cases (e.g. ABC circuit). Secondary grinding is conducted using ball mills or pebble mills.

Jan 1, 1985

By Tim Arnold

"Justified is a show on FX that takes place in Kentucky coal country. The two main characters, a cop named Raylan and a criminal named Boyd, are adversarial to the very end, yet they manage to maintain a seemingly inexplicable bond of friendship through it all. The final episode ends (spoiler alert) with Boyd asking Raylan why that is. He responds, “If I allow myself to be sentimental, there is one thing I wander back to” Boyd responds, “We dug coal together.” Fade to black.What creates these types of bonds between friends and co-workers in mining? I don’t know about you, but many of my best friends I met in mining. Certainly the people I respect the most in this world are a part of our industry. Good, honest, honorable men and women. And I am not just talking about the leaders of our industry. I am talking about great miners who taught me how to do the right thing and also be productive.I have had the pleasure to work for some great people and the misfortune of working for some of the loudest screamers. What I consider the worst butt-chewing in my life may surprise you. I once worked for a man I respected, because he showed me respect. He went on a business trip and left some instructions. For some reason, I was able to justify to myself that they applied to everybody but me, and I disobeyed them. When he returned he called me into his office and said to me: “Tim, you pissed me off when you did that.” He said it quietly and with no anger. I had lost his respect. This devastated me more than any screaming shift boss ever could have. I learned a lot about values from that conversation.Most of us will spend more time at work than we will with our families over a lifetime. It is natural that tight bonds be created at work. What I believe makes mining special is that these bonds are so strong. They are strengthened by the incredibly hard work our miners do. They work at all hours, on holidays and in all sorts of extreme weather conditions. The physical demands of the job are sometimes exhausting. Our bonds are further reinforced because the work is dangerous. Not only does management watch out for the wellbeing of their people, but each and every one of us looks out for one another. The bonds are made tight because our people are so passionate about what they do, no matter the department or profession. Finally, they are strong because of the thousands in the industry that keep doing the right thing, every day. We make great friends in this industry because of the strength of character of our people. That is why Boyd and Raylan respected one another so much."

Sep 1, 2016

By José Maria Silva, Eugênio Oliveira, Ruberlan Silva, Thiago Souza, Lucas Reis, Lorena Guimarães, Matheus Bianchetti

Copper mine operations consistently generate a large quantity of tailings after their concentration processing. These tailings are either piled up or stored in a dam, where both alternatives of disposal lead to environmental impacts. The dam copper tailings have a huge potential for by-product production thus improving sustainability and profitability in industrial operations. This paper describes a study aiming at producing a magnetite pellet feed as a by-product from a dam chalcopyrite flotation tailings and generating free magnetite non-magnetic rougher tailings. The chemical assay and mineralogy analysis of dam copper flotation tailings indicate low Fe grade (6.34 wt%), high SiO2 grade (63.14 wt%), low magnetite (3.6 wt%), and high iron silicates content (22.72 wt%). The complex mineralogy of these tailings leads to the need of grinding the rougher magnetite pellet feed as fine as 80% of particles smaller than 20 μm ( P80) aiming at improving magnetite liberation. The proposed process route comprises a scalping screen, low field rougher, and cleaner magnetic separations using a drum magnetic separator (80 kA/m or 1000 Gauss), followed by silicates reverse cationic flotation as a recleaner step. With this process route, it was possible to produce a high-quality magnetite pellet feed reaching 68.00 wt% of Fe, 2.13 wt% of SiO2, 0.51 wt% of Al2O3, and 95.1 wt% of magnetite. The Blaine specific surface area was 2300 cm2/ g, being in the range recommended for pelletizing (1900 up to 3000 cm2/ g). The total mass, Fe, SiO2, Al2O3, and magnetite recoveries were 2.77%, 29.71%, 0.09%, 0.12%, and 73.17%, respectively. Most of the magnetite losses, around 20% of total magnetite fed, occurred in the oversize of the scalping screen. Additionally, it generated non-magnetic rougher tailings with less than 1.0 wt% of magnetite that could be used as by-products and reduced the amount of tailings disposal in a dam. This study contributes toward the sustainability of operation, minimizing tailings disposal.

Sep 28, 2022

By Ross W. Smith

In recent years there has been a considerable amount of research work done relative to the effect of pretreatment and aging in water on the surface properties of both simple metal oxides and more complex oxides such as the silicate minerals 1-6. Of particular interest is the work of Somasundaran6 who states that after preparing minerals by size reduction and washing with dilute acids "... it is essential to treat it (the mineral) with water in order to remove any effects of leaching itself." Somasundaran also states, "... it is advisable to use a solution close to the point of zero charge for conditioning purposes." Parksl notes that, "Dehydration, dehydroxylation, and increased crystallinity can be expected to decrease the PZC. The presence of anionic impurities or of pH-independent potential determining ions will decrease the PZC. Cationic species will increase the PZC." Healy and Jellett4 believe that in the Zn0-water system "the surface charge of Zn0 in water and each pH is determined by the concentration and adsorption of each hydrolyzed (charged and uncharged) Zn(II) species." Finally, according to Parks 2, "The PZC of an unaltered com¬plex oxide in a system devoid of specific electrolytes is approximately the average of the PZC's of its component oxides... Equilibration with water results in loss of mono and divalent cations by exchange with H+, thus a loss of influence on the PZC by those cations, i.e., a shift in the PZC with time in the direction of that remaining oxide. The present paper investigates the change of point of zero charge (PZC) of a number of simple oxides and several complex oxides as a function of aging time in water. In some cases acid pretreatment of minerals was performed. However, in most cases the minerals were not acid pretreated. In several systems pH change as a function of aging time in water was monitored.

Jan 1, 1972

By J. H. Schuenemeyer

Uncertainty estimates on coal resources were computed as part of the U.S. Geological Survey’s National Coal Resource Assessment study of more than 60 coal beds and zones in the Appalachian Basin, the Colorado Plateau, the Gulf Coast, the Illinois Basin, and the Northern Rocky Mountains and Great Plains. The estimates were made to provide zone specific measures of uncertainty on the historical categories of geological assurance, namely measured, indicated, inferred and hypothetical. Previous estimates were based solely upon distance from a drill hole. These new estimates incorporate site-specific variability and spatial correlation and indicate that there is considerable difference in variability within and between regions. Uncertainty estimates for the measured category are discussed in this paper.

Jan 1, 2001

By K. Oraee

Mining Ventures are considered as high risk projects and therefore managing the risks is inevitable. Risk assessment is an important part of the complex process of risk management, hence applying appropriated and practical methods for ranking the risks associated with projects, can help to perform a better risk management. In this research the applicability of using Techniques for Order Preference by Similarity to Ideal Solution (TOPSIS) method for risk ranking in an underground mine, extracting by block caving method, was studied. Via this method, the risk associated with reserve estimation ranked as the first while in conventional method (P-I Matrix method) located in the sixteenth. Also there were significant differences in ranks of the other risks. Considering the more criteria, with different weights, in comparison with conventional methods, the results comprised from TOPSIS method are more reliable. By implementing this method risks are ranked better and more realistic and consequently then will be managed more efficient.

Jan 1, 2011

By Ronald J. Riberich

The Mineral Economics and Management Society (MEMS) held its fifth annual conference in Montreal, Quebec, Canada earlier this year. “The Minerals Industry: Responding to the Global Challenge” was the first MEMS conference to be held outside of the United States. About 125 mining- and minerals-related professionals attended. The MEMS program included six sessions and three distinguished speaker addresses. The session topics included: “Minerals in the Macro economy: Development in Demand,” “Trends in Global Metals Supply: The Producers’ Challenge,” “Global Environmental Issues: Policy Perspectives,” “Global Environmental Issues: Quantitative Analysis” and “Minerals in the CIS: Phoenix or Albatross?” A student session was also offered. It provided a competition for monetary awards for outstanding papers.

Jan 1, 1996

By Thomas J. Lien

Granitic Pegmatite deposits are the chief source of commercial feldspar, micas, lithium minerals, tantalum-columbium, beryl, and certain types of kaolin. The output from pegmatite mines in the United States is small compared to other mineral products in terms of bulk or value, and much of it comprises only minor metals and nonmetals. Nevertheless, pegmatite minerals play a vital part in our domestic industrial economy, particularly in the ceramic and electrical industries. Numerous special purpose uses also are important, even though they require small quantities of raw materials. In recent years, realizing the potential importance of the pegmatite minerals, the U.S. Geological Survey, the United States Bureau of Mines, several state Bureaus of Mines, and a few private companies have carried on extensive programs of pegmatite studies in the New England and southeastern states, in the Black Hills area of South Dakota, in the Rocky Mountain region of Wyoming, Colorado, and New Mexico, and in various parts of Washington, Idaho, Utah, Nevada, Arizona, and California. Currently, some of the pegmatite minerals such as micas and spodumene are selectively separated by the flotation process. To a lesser extent a few plants are selectively floating feldspar and quartz. Much of the credit for the above progress goes to the fine work done by U.S. Bureau of Mines (1), and companies such as Foote Minerals (2). Additional research efforts by the New Mexico Bureau of Mines (3) has successfully demonstrated selective separation of micas, beryl, spodumene, lepidolite, microlite, quartz and feldspar from a complex Pegmatite containing all these minerals. Since the nature of the mineralization of various valuable components of a pegmatite deposit is such that selective separation of some of these can be carried out at a coarse size using the Heavy Media Separation technique, it was felt that such a system should be investigated for selective preconcentration of their minerals. It was also felt that of all the :MS systems available, the DYNA WHIRLPOOL (DWP) device which allows a close control and adjustment of specific gravity should provide a means of achieving the above goal. Once the desired preconcentration of one or more of the pegmatite mineral assemblage is achieved, the available selective flotation techniques should provide effective recovery of various minerals into marketable products. This paper presents technical and economic aspects of selective preconcentration of some of the pegmatite minerals followed by selective flotation to produce marketable products.

Jan 1, 1978

By Norbert T. Rogers

An accepted statement of fact is that, next to agriculture, transportation is the second most important industry in the world. The transportation networks of the United States have greatly contributed to our nation's growth and prosperity. The objective here is to make the reader aware of the need for communication between geologists, mining engineers, purchasing agents, and transportation managers. Only through a cooperative effort is it possible to reap the benefits of transportation in the industrial minerals field. Transportation is often thought of in terms of trucks, rail cars, barges, and covered wagons. There is much more. Corning Inc. Corning Glass Works is a worldwide organization with more than $2 billion in annual sales. It supplies more than 60,000 different products a year to some 47,000 customer firms and millions of individual consumers. Corning operates 32 of its own plants worldwide and is also an investor with a 50-50 or minority position in 24 affiliated companies in 11 countries. Corning competes in four broad business categories: • specialty glass and ceramics; • consumer housewares; • laboratory sciences; and • telecommunications Binding these four sectors together is the glue of technology. Coming's research laboratory, established in 1908, was one of the first in American industry. That early commitment to research has never wavered. Today, Corning spends annually on research and devel¬opment, as a percentage of sales, at double the average rate for all manufacturing industry in the US. Some 1500 scientists, engineers, and support personnel are now employed at the company's research and development centers in the US, Japan, and France. Petalite background A family of materials melted conventionally as a glass, then converted by special processing to a ceramic was invented in 1957. One of the basic minerals in this glass ceramic product is petalite. Petalite is a monoclinic mineral with a framework silicate structure and a low iron content, about 0.06% Fe2O3. Petalite is found in very few places throughout the world and no commercial petalite deposit has been found in the United States. Sizable deposits occur in Zimbabwe, Southwest Africa, Brazil, Australia, the Soviet Union, and Sweden. Coming's purchasing and geology departments located a source of petalite with proven reserves in what was then known as Rhodesia. The supplier was Bikita Minerals. The relationship with Bikita was one in which Bikita supplied bulk ore that Corning processed into a finished material at its US facility. This bulk ore method of shipment resulted in high losses through contamination and processing. It also caused tank upsets at the Corning plant because of iron contamination picked up through the numerous handlings of this product in bulk. The relationship with Bikita continued until 1965 when the white political leadership of Rhodesia declared its independence from Great Britain. This led to the imposition of international sanctions. The sanctions were lifted in 1980 and the relationship with Bikita was reestablished in 1983.

Jan 1, 1989

By J. MacFadyen

The U.S. cement industry experienced its best year ever during 2004 in terms of production and shipments of cement. Clinker, portland and masonry cements production and shipments were up considerably. Clinker production as reported to the U.S. Geological Survey (USGS) was 87.75 Mt (96.73 million st), an increase of 5.4 percent. Gray and white portland cement production from domestic and imported clinker was estimated to be 91.6 Mt (101 million st), up 5 Mt (5.5 million st) from 2003.

Jan 1, 2005

By C. J. Roos

Ground engaging tools are used to prevent damage to the main components of earth-moving equipment. These tools consist of everything from shovel teeth to replaceable drill bits to dozer wear plates. The costs of these ?consumable? items are increasing with the costs of raw materials. This project developed a tool to be used by Newmont Mining Corporation to predict the consumption of excavator teeth. This paper presents the results of a Montana Tech research project in which an equation was developed to predict excavator teeth consumption based on production rates and rock properties.

Jan 1, 2009

By Richard E. Sabaski

The demand placed on the mining industry in the past 15 years for increased production, coupled with lower grade ore and higher cost capital, has resulted in a noticeable increase in grinding mill sizes. The pressure to increase mill size continues. During the mid sixty's and early seventy's, ?larger? conventional ball mills were in the range of 13 - 16-1/2 f t. diameter (4 - 5 m) increasing by the mid 70's to 18 ft. (5.5 m) diameter. At the same time, autogenous mills expanded from 24 - 32 ft. (7.3 - 9.1 m) to the present 34 and 36 ft. (10.b and 11.0 m) diameters. These size pioneers of 16-1/2, 18, and 36 ft. diameter mills from Allis-Chalmers have been free from structural problems, because they were analyzed, modeled, designed, and field tested to meet the challenge.

Jan 1, 1981

By S. J. Neethling

The flotation froth structure and motion determines the amount of entrained gangue that is collected to the concentrate. Despite this important role in the overall performance, the behaviour of the froth is still ill understood. To date, predominantly empirical models have been developed to describe entrainment. A fundamentally based model is described and used here in an attempt to improve the understanding of entrainment. This general froth simulator (UMIST FrothSim) allows the modelling of a wide range of flotation conditions, as it takes account of a large number of the physical phenomena that occur within flotation froths. The model firstly describes gas motion and bubble coalescence, and the water motion based on gravitational, viscous and capillary effects. The motion of the solids distinguishes between various solids classes based on hydrophobicity, particle size and density and models them by including the effects of Geometric and Plateau border dispersion, particle settling and the motion of the water. The aim of this paper is to show the applicability of this model to explain the observed entrainment and collection of gangue. This is done by comparing model predictions with the experimentally observed relationship between the gangue and water recoveries. The model predicts the identical trends, which are explained in terms of the interaction between the linear effects of water motion and hindered settling and the non-linear effect of particle dispersion.

Jan 1, 2001

By Ian McFeat-Smith

Despite a present, short-term economic recession, a remarkable enthusiasm exists in Hong Kong for building infrastructure including major tunnel projects. This paper provides details of current and recent bored tunnel works together with an insight into the impressive list of future underground projects planned by the MTRC,KCRC, Highways Department and Drainage Services Department for the next decade. Risks for each of these works including pipejacking, mixed face and rock tunnelling generally in Hong Kong are also identified. From this is evident that the scale and difficulty of such works continues to increase, requiring the use of more sophisticated methods of construction, the need for better methods of assessing and managing risks and for Government to utilize improved, more equitable Conditions of Contract for such major tunnelling projects.

Jan 1, 2001

By M. E. Rossi

This paper discusses the use of Conditional Simulation (CS) models to provide mill feed grade profiles for different time periods. The conventional approach of classifying block estimates as ore or waste generally does not adequately represent dilution, lost ore and the anticipated grade control data, including variability of mill feed from the pit and possible stockpiles. The detailed simulation of grade control practices can be done, but at the Pre- or Feasibility stage of the project may be impractical, since drawing dig limits on multiple benches is tedious and time consuming. Using the Feasibility Grade Control (FGC) method as developed by the Centre for Computational Geostatistics (CCG, University of Alberta-Edmonton), the CS models can be processed quickly to establish dilution and lost ore, and predict daily or short-term feed to the mill. The simulated nodes can be aggregated into selective mining units with adequate representation of likely geometries to be recovered from the pit, to mimic anticipated selectivity. An example from a large copper deposit is shown. The study provides an estimated stream of tonnages and grades fed to the plant by mining periods of interest and based on a specific mine design and schedule. The resulting cash flows support the economic and financial analyses of the Feasibility Study; also leads to improving mine schedules; and aids in developing blending schemes if necessary. INTRODUCTION The conventional approach of separating mineralized material into ore or waste categories does not always include a realistic amount of dilution and ore loss. Also, often it does not provide a good estimate of the grade that will be fed to the mill. If the grade control estimates are unbiased, they will over the long run represent the long-term average of grades fed to the mill; but the anticipated variability of mill feed from the pit and stockpile sources may be misrepresented. Some references on traditional grade control implementations can be found in Chunnett (1982); Davis et al. (1989); Srivastava et al. (1992); and Nowak (1992). Alternative methods based on economic variables improved significantly on the purely grade-based control methods, see Douglas et al. (1994). Further developments involved the use of geostatistical conditional simulations (CS) and profit models, which in several cases have been successfully implemented (Aguilar and Rossi, 1996; Rossi, 1997; Deutsch et al., 2000; Norrena and Deutsch, 2002; Neufeld, 2005; Jewbali and Dimitrakopoulos, 2009). But they can be impractical, mostly due to the lack of understanding of the methodology involved; even if semi-automatic dig limit drawing is implemented, there is always a need for is tedious and time consuming checking and corrections, even if using a single profit model derived from the simulated grades.

Jan 1, 2019

By Sotiris N. Kamenopoulos, Zach Agioutantis

Rare earth elements (REEs) are considered critical minerals for industrial and defense sectors. REEs are not as rare as the word “rare” portrays; yet, the exploitable and/or profitable deposits of REEs may be found only in certain geographical areas. The political and social conditions characterizing these areas may not always be in favor of mining operations. These conditions are imposing the need for extra consideration on the geopolitical constraints prior to any decision-making and before any mining project begins. This study assesses the risk related to mining projects for areas that feature REE deposits based on a geopolitical viewpoint. Probable ranking differences between the current assessment and a 2015 assessment are discussed. The comparative indicators used and the appraisal procedure applied in this comparison are based on a number of different geopolitical indicators. Several ranking changes occurred between 2015 and 2019.

By M. J. Gula, S. S. Xue, E. P. Horwitz

A study has been conducted to remove iron from sulfate solutions using Eichrom's Dipexo® extractant, P,P'-di(2ethylhexyl) methanediphosponic acid (H2DEH[MDP]). It is found that this extractant can effectively and selectively extract ferric ion from highly acidic solutions. Ninety-nine percent of the iron was extracted from a simulated feed solution in a single stage. The separation factor, Fe/Zn, was 106. Over 90% of the iron in a loaded organic can be recovered in an aqueous solution by reductive stripping. This paper presents the experimental results. A new process for iron removal using Dipex extractant is described and discussed.

Jan 1, 1999

By M. J. Hannan

Considerable interest has arisen in developing analytical methods suitable for measuring resource commodity substitution patterns. some of this work has applied the Translog method to estimate actual elasticities of substitution. Recent examples incl.uae Privolos and Dunietz (1987), Kopp and Smith (1983), and Moroney and Trapani (1983). Another method, one which has received attention earlier in the work of Fisher and Pry (1970), is that of the logistic or diffusion function. We believe that the latter method has properties suitable for analyzing current problems of material substitution. The present study thus evaluates this method in its original logistic form as well as an extended version incorporating additional explanatory influences. The analysis is applied to copper/aluminum substitution and iron ore beneficiation. Substitution for copper by aluminum is examined in the building wire and cable, and magnet wire end-use markets. For iron ore, the substitution of pellets for sinter is considered for the U. S. market.

Jan 1, 1990

By D. E. Walsh

With the exception of the development of large scale mining equipment (haul trucks, draglines, shovels, etc.), there are likely few other candidates responsible for the ability to exploit large tonnage, low grade deposits, than the development of large capacity comminution equipment and circuits; crushers and grinding mills. Ball mills are often the final step in the comminution process and are responsible for providing what should be the optimum particle size distribution of ore to subsequent mineral concentration steps in the flowsheet. Because comminution processes are such high cost centers for milling operations, both capital and operating costs, an enormous amount of research has been conducted to study and model their performance, in order to improve efficiencies (Kelsall, et al., 1969; Austin et al., 1984; Napier-Munn, et al., 1999; Powell and Smit, 2001). With respect to modeling ball mills, estimates of the breakage rates for individual size classes of ore particles are fundamental, as are the particle size class breakage functions (the progeny of particle sizes produced from breaking a coarser particle size class), also termed appearance functions. Fundamental research into particle breakage in tumbling mills focuses on how much energy is input into single particles versus how they break and what size distribution of particles results. Several test methods, including JKMRC?s well known dual pendulum test and drop weight test, have been developed for the breakage of coarse particles down to 6 mm in size (Napier-Munn, et al., 1999). Work on the breakage of finer particles is still an area of intense research and single particle breakage is being investigated as are multiple particle, fixed bed methods (Hoffler and Herbst, 1990; Bourgeois et al., 1992; Whiten, 2007).

Jan 1, 2011

By Peter Shuttleworth, Chris Fesq, Eddie Woods

Precast concrete segmental linings for tunnels have traditionally been designed with conventional steel bar reinforcement. In many cases, this has been satisfactory in service, but in others, major problems have occurred with the durability of the linings. Commonly this has resulted from corrosion of the reinforcement, mainly from chloridesin ground water, causing spalling of the concrete and leading to very expensive and disruptive repair programs. This paper discusses the relative merits of designing tunnel linings with steel fiber reinforcement to provide long-term durability, improved impact resistance and toughness for greater load capacity across joints, enhanced robustness during transportation and erection, plus improved fire resistance with the addition of polypropylene fibers. Guidance is also given in the selection of the correct fiber type, mix design and testing methods to establish the optimum dosage required and production techniques to ensure even distribution and compaction.

Jan 1, 2005