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By S. G. Malghan

This paper describes uses of sodium sulfide in the flotation of oxide and sulfide minerals of copper, lead, and zinc. The activation and depression effects of sodium sulfide are of particular importance because of their applications with oxidized lead and copper ores. In spite of its industrial importance; however, the nature of the heterogenious reactions between sulfide ions in solution and the surface of oxidized minerals has not been fully understood. Hence, proposed mechanisms of the sulfide action in flotation, methods of measuring and monitoring of sodium sulfide in flotation pulps, and variables influencing the sulfide addition are analyzed. A review of recent studies shows that sodium sulfide addition to flotation pulps can be monitored and hence the optimum dosage controlled using the platinum and/or sulfide specific ion electrodes. The use of these electrodes for improved reproducibility of bench-scale experimental data and plant implementation of laboratory results is described.

Jan 1, 1985

By F. Robert Hollo

Programmable controllers have achieved remarkable acceptance over the relatively few years since their introduction. They provide some unique advantages over conventional relay and solid-state logic, which they often replace. Programmable controllers are discussed in both conceptual and functional terms, followed by an exploration of their applicability to material handling tasks with particular emphasis on conveyor systems.

Jan 1, 1973

By A. S. Atkins

The interest in the use of micro- organisms in the leaching of sulphide minerals has been traditionally exploited as a scavenger process for the recovery of valuable metal by- products from waste ore dumps. Environmental concern on sulphur emission from conventional pyrometallurgical plants together with the cost of stack cleaning systems to comply with legislative control also indicate baccerial leaching to offer a low cost treatment for the processing of sulphide minerals. The paper describes the effect and limits of relatively coarse particles on the complete leaching of pyrite and its importance to the practical application in dump leaching operations of sulphide minerals. It has also been demonstrated that static leaching techniques have encouraging economic potential for process plant operations compared with agitated leaching systems.

Jan 1, 1984

By S. L. Barua

An industrial engineering and computer simulation study was conducted on reclamation operations to evaluate the possibility of integrating mining and reclamation operations, and to evaluate the factors which influence the production potential of scrapers. The study was done in a southern Illinois strip coal mine producing approximately 2.27 M metric tons (2.5 million short tons) of clean coal annually. The main outcomes of this study are (a) it is possible to reduce reclamation cost about 20-25 percent by integrating reclamation and mining operations, (b) haul distance has the most significant effect on scraper production, (c) push-pull is the best mode of operation for wheel scrapers for topsoil/subsoil removal, and (d) historical data obtained from the mine for one year show that average dozer productivity in rock grading is about 60 percent lower than the expected production; similar data for scraper is about 25 percent less.

Jan 1, 1981

By David B. Brooks

I gratefully acknowledge the help of a number of American and Canadian geologists, in both federal surveys and in private firms, who took the time to discuss this problem with me. Hans Landsberg and Bruce Netschert also followed the study with interest and encouragement. In their 1961 monograph, THE FUTURE SUPPLY OF THE MAJOR METALS, Bruce Netschert and Hans Landsberg noted that identified potential resources (that is, known but submarginal resources) of lead and zinc were much lower relative to reserves (that is, known and supermarginal resources) than was the same ratio for other metals.1/ Put another way, it seemed that for such metals as iron, manganese, copper, and aluminum, slightly more favorable economic conditions or modest advances in technology would greatly increase reserves by permitting the exploitation of vest quantities of leaner or deeper or otherwise less valuable mineral deposits. But for lead and zinc, Netschert and Landsberg concluded that either: "(1) there is relatively little material below present cutoff grades; [or] (2) such material exists, but for some reason there are no data.? 2/ This situation, which they called "the lead-zinc anomaly" has been subsequently discussed by other authors. The purpose of this paper is to carry the discussion further by examining the evidence in favor of (1) and (2) and by advancing a third alternative.

Jan 1, 1967

"Above ground, elevated belt conveyors that span more than 200 m (656 ft) between support points can cross valleys, rivers, forests and buildings with a minimal footprint. The cable bridge conveyor (CBC) is a new type of suspension bridge based belt conveyor system that has long spans between support points. It combines a typical belt conveyor and an improved simple suspension bridge to form a conveyor bridge. The improved simple suspension bridge places a widened bridge deck directly on suspended cables, without the need for high truss towers. The benefits include reduced cost and increase aerodynamic stability compared to conventional suspension bridges. The CBC’s compatibility with current belt conveyors allows versatility in application.A belt conveyor is a ubiquitous material handling system. Conveyors can be placed directly on ground or elevated above ground by support structures. Considerations of cost, design, environment, civil work, safety and process requirements are all factors in choosing the ground-based or elevated conveyors (Zhang, 2014). The ground-based conveyor has the lowest structural cost when the conveyor is placed on an existing road. Maintenance access is easy and straightforward. Compared to the groundbased conveyor, the elevated conveyor can cross existing buildings and structures, give passage to traffic beneath the conveyor, has a smaller footprint and requires less civil work to pass mountainous areas. The drawback of the elevated conveyor is higher structural cost, which can be compared with savings in civil work and other benefits. Conventional elevated conveyors are supported by rigid truss-type structures, with a typical span of 15 to 25 m (50 to 82 ft) between concrete support bents or steel trestles. Triangular truss, using steel pipes instead of hot rolled steel sections, is more efficient. The typical span of a triangular truss-supported conveyor is around 30 to 40 m (100 to 130 ft), while the weight is about 10 percent less than conventional box truss with a shorter span (Jennings, 2013).Long-span elevated structures based on suspension bridge is another step forward in increasing the distance between support bents, reaching 100 to 400 m (330 to 1,312 ft) and beyond. The wide distance between the support points of an elevated conveyor offers unique benefits. The conveyor can cross rivers, valleys, highways, forests and other obstacles with minimal footprint and reduced civil work. The versatility from long-span conveyors makes bulk material transportation over previously impossible terrains now a feasible option."

Jan 1, 2014

By Rameshwar Sah, PK GHORUI, LR SINGH, SIVALINGARAJU BARISETTY, SHYAM YADAV

Fly ash is a by-product generated by the combustion of coal in thermal power plants. Its disposal is a major environmental concern for these power plants. Though a considerable part of fly ash is used in cement making and brick manufacturing, a substantial quantity remains unutilized. Bentonite is commonly used as binder in the micropelletization of process waste to attain the mechanical strength required for handling and transportation. The present paper deals with the partial replacement of bentonite with fly ash in the micropelletization process without affecting the quality of the micropellets. The mechanisms of both the binders are discussed. The bonding of particles by bentonite is a physical mechanism, while fly-ash bonding is a chemical mechanism. Silica and alumina are the major constituents present in fly ash along with lime. In the presence of water, the alumino-silicates and unhydrated lime present in fly ash undergo a pozzolanic reaction and form cementitious bonds, which hold the particles together. Use of fly ash as alternative binder for bentonite has cost benefits besides providing a better utilization option for fly ash.

By William Gleason

"It is the largest mining exhibition in the world that attracts thousands of attendees from around the world to Las Vegas, NV once every four years. Despite the recent struggles in the mining industry, MINExpo International 2016 promises to be as big as ever. In the following pages, Mining Engineering takes a look what some of the more than 1,800 companies plan to showcase during the three-day exhibition.CaterpillarCaterpillar will support MINExpo 2016 with an exhibit showcasing machines, technology, expertise and practical knowledge that miners can apply to help address their cost, productivity and efficiency challenges in today’s mining environment.Caterpillar will once again occupy the largest space at the event and will showcase both surface and underground machines, but the talk at the booth will focus on how Cat technology and know-how combines to help mining operations address and solve the issues that are most important to them. The main stage in the exhibit will feature presentations describing how mining companies, Cat dealers and Caterpillar work together to improve operations.“The challenge for all in the mining industry now is to optimize operations — to drive costs down while creating sustainable businesses that can weather downturns,” said Caterpillar Resource Industries group president Denise Johnson. “We believe that through our expertise and the knowledge of our dealers —combined with innovative technologies and our growing data analysis capabilities — we can help them not only survive, but thrive in these challenging times.” Johnson was selected by the National Mining Association (NMA) to chair MINExpo 2016. “Chairing this show is a great honor, and it’s a testament to Caterpillar’s partnership with this critical industry,” she said. “We’re proud to be a long-time supporter of the NMA, and we are excited to participate in another MINExpo. It’s an opportunity for us all to learn from each other how to increase productivity, control costs and improve overall operations.”Surface mining displays. The surface mining section of the Caterpillar exhibit will showcase the new MD6420C rotary drill. This is autonomy ready and optionally equipped to leverage the safety and productivity benefits of Cat MineStar Terrain. This high-precision drill management system optimizes utilization and improves drilling and blasting operations by accurately guiding the operator and improving precision of hole placement and drilling depth — and the next step is fully autonomous operation, Command for drilling. The third-generation drill incorporates proven Cat components throughout for superior reliability and durability."

Sep 1, 2016

By John H. Lichtblau

There are three parties to the oil imports controversy: the domestic oil producers, whose side has just been ably summarized by Mr. Jameson; the oil importers; and the public. Domestic producers and importers are both motivated by economic self-interests, that is by their natural and legitimate desire for profit maximization, in their respective positions. Thus, domestic producers, rightly, regard every barrel of imported crude oil (with the exception of some specialty crudes) as a displacement of a barrel of their own crude. Hence, the lower the import Level the better they like it. Conversely, U .S. refiners whose plants are located at the seaboard or at certain inland waterways generally welcome a higher level of imports because refiner profits are based primarily on the spread between the crude oil price and the refined products price, since crude oil represents by far the refiner?s largest cost factor. The relatively low cost of foreign oil means therefore higher profits to those refiners able to process such oil, This applies particularly to integrated companies whose own domestic oil production is insufficient, to meet their refinery requirements but who have developed ample low-cost foreign oil supplies.

Jan 1, 1962

By SUHAINA ISMAIL, NORLIA BAHARUN, SHAIK ABDUL RAHMAN, WAN NUR SYAFIQAH ANUAR, MOHAMMAD REZAEI ARDANI

Refractory gold ore contains sulfide minerals like pyrite, chalcopyrite and sphalerite that are difficult to be directly leached by cyanidation or by lixiviants such as thiourea and halides. In such cases, it is necessary to perform oxidative pretreatment of the ore to oxidize the sulfide matrix, and gold particles can be exposed to the solution during the leaching process [1]. In recent years, hypochlorite and chloride solutions have been introduced as alternative materials for hydrometallurgical methods of gold extraction instead of cyanide solution [2]. A previous study by Hasab et al. [3] reported that the gold dissolution rate in hypochlorite solution was higher than in the cyanidation process, due to the presence of hypochlorous acid (HOCl) as a strong oxidizing agent. In a hypochlorite leaching system, the change in pH can influence the presence of oxidant species in the solution: the hypochlorite ion (OCl−) is stable in pH greater than 7.5, HOCl can be found in pH between 4.0 and 7.5, and aqueous chlorine (Cl2 (aq)) is the predominant oxidant when pH is below 4.0. As HOCl is the most effective oxidizing agent for gold extraction, pH should be maintained in the range of HOCl stability [4].

When science and the human spirit come together amazing things can happen. This was perhaps never more evident than through the events that unfolded during August and October in a remote desert in northern Chile. On Aug. 5, the main shaft of the San José copper and gold mine near Copiapó in Chile?s Atacama Region collapsed, leaving 33 miners trapped more than 624 m (2,000 ft) beneath the earth?s surface.

Jan 1, 2010

By T. J. Lutz, D. S. Yantek, L. Yan, J. R. Srednicki, J. A. Yonkey, G. T. Homce

Federal regulations require the installation of refuge alternatives in underground coal mines. Of the inuse refuge alternatives, more than 95 percent are mobile refuge alternatives, with the remainder being built-in-place (BIP) refuge alternatives. Heat/humidity buildup has been one of the major concerns with mobile refuge alternatives. For BIP refuge alternatives, however, there is a lack of in-mine heat/humidity test data to determine the extent of heat and humidity buildup. To quantify heat/humidity buildup in BIP refuge alternatives, the U.S. National Institute for Occupational Safety and Health (NIOSH) performed a series of heat/humidity tests on a 60-person BIP refuge alternative with and without a borehole air supply. At various times during the year, tests were performed with cooled, heated or unconditioned borehole air to examine how various outdoor temperatures may affect the thermal conditions inside a BIP refuge alternative. The results show that the air supplied to a BIP refuge alternative may require heating or cooling, depending on the outside air temperatures and the temperature of the mine. For example, during tests with an external ambient temperature above 21 °C (70 °F) and a relative humidity of 90 percent, providing 13 °C (55 °F) dew point air at 775 scfm, which is slightly higher than the mandated flow rate of 12.5 scfm per person, kept the internal apparent temperature below the mandated 35 °C (95 °F). Results for each test case are presented.

Jan 1, 2018

By Aixiang Wu, Minjie Zhang, Zhuen Ruan, Yiming Wang

This paper combines theoretical and experimental analysis to conduct relevant research to improve the accuracy of predicting paste yield stress by slump flow. The analytical model of slump flow for yield stress is derived based on a mini-cylindrical mold with a height-to-diameter ratio of 1. It shows that the dimensionless slump flow is a monotonic decreasing function of the dimensionless yield stress and is independent of the material type (specific gravity), which provides a theoretical basis for quantifying the rheological properties of paste with slump flow. Three different tailing-prepared pastes were tested for their slump flow and implemented rheological tests simultaneously. The yield stress is obtained based on the Bingham model fit, as the measured value of the yield stress is substituted into the derived theoretical model. The studied pastes yield stresses range from 34.78 to 524.08 Pa, with corresponding dimensionless slump flow of 3.43 to 1.09. The results showed that the calculated slump flows were generally greater than the measured values. The analysis showed that this was mainly due to the thixotropy of the paste, with minor deviations ranging from − 1.5 to 5.8% for the less thixotropic pasted prepared from tailing C. An approximate analytical solution for yield stress as a function of slump flow is obtained using Taylor’s formula. However, it is unsuitable for predicting the yield stress because the yield stress calculated by this function is much higher than the measured value. The empirical yield stress model was constructed and experimentally verified. The results show that the empirical formula has high accuracy and good generality. The deviation of the studied pastes is between − 15 and 5%, which provides a practical method for rapid and accurate prediction of paste yield stress in mine sites.

Jun 1, 2023

By C. Dirscherl

"Declining ore grade, leading to increased material transport and plant throughput requirements, is one of the major challenges in the current mining environment. This is accompanied by rising energy and labor costs, decreasing plant productivity and the requirement for highest plant availability. Siemens’ answer is the latest gearless drive technology for grinding and conveying. Gearless drive solutions are surpassing the mechanical limits of conventional drive systems serving to utilize the principle of economies of scale. By elimination of various components of the drive train the maintenance activities and spare parts inventories are reduced. The advantages are culminating in the incomparable availability of the Siemens’ gearless drive technology of 99.46 to 99.71% - as confirmed by real operational data from the Antapaccay mine in Peru. It was the first plant worldwide to use gearless drives for both applications. KEYWORDS: Gearless Mill Drives, Gearless Conveyor Drives, Availability, SAG Mill, Ball Mill, Overland Conveyor, Antapaccay INTRODUCTION – THE GEARLESS PRINCIPLE The principle idea behind a gearless drive system is to reduce the number of components and diversity of parts. Especially those components that are at the edge of current manufacturing or power limits are eliminated. The used equipment provides the possibility to scale up and increase the power transmitted to the driven machine. This finally results in a possible increase of throughput respectively transported or processed material. In order to apply this principle of simplification we will take a look at the components of a conventional drive system consisting of: - Driven equipment (mill, conveyor, slurry pump…) - Components altering the rated speed (gearboxes, girth gear / pinion) - The electric motor - Starting devices for the motor (VSD, CCV, LRS, clutch…), which are necessary because a direct across-the-line start of high power motors with load would result in a significant drop in the line supply voltage - Alternatively a variable speed drive (VSD) or cycloconverter (CCV) to utilize the possibility of speed variation during operation - The electrical supply system (cables, switchgear, transformers, protection equipment) Intermediate gearboxes are not required when a motor is used with a rated speed that directly matches the speed requirement of the driven equipment. Furthermore the VSD can be used to smoothly start the motor and to vary speed during operation, which means that it satisfies both requirements."

Jan 1, 2015

By B. G. White

Traditional interpretations of vein ore deposits in the Coeur d' Alene Mining District, such as the view that these deposits formed in a transcurrent tectonic regime during the Precambrian, are being supplanted by the view that the deposits (1) formed in low-grade metamorphic shear zones similar to those that host an important type of gold deposit, (2) display features, such as wall rock carbonate zoning and vein zoning, that are common to ore deposits elsewhere, and (3) are probably Mesozoic and possibly related to emplacement of the Idaho batholith. In recent years, new interpretations have led to major ore discoveries that are likely to extend the life of the district for decades.

Jan 1, 1998

By David T. Kao

The energy situation the world faced during the decade of the Seventies resulted in actions throughout the free world to reduce its dependence on OPEC oil. Many nations heeded the indicators early in that decade and commenced efforts to reduce their oil requirements. Those nations which did not heed these warnings had the message brought to them more emphatically in the last portion of the decade with the further rapid and continuing rise in prices of OPEC oil. Furthermore, the demonstrated unstable nature of large oil-producing countries has made it clear to all free world nations that their energy demands of the future must be provided for by some more stable and assured supply. Now, early in the decade of the Eighties, we see the need for expanded use of coal as an energy supply to be essential. The result in 1980 and 1981 has been a great increase in demand for steam coal worldwide. In essence, a new business for the United States has developed in steam coal export. In the United States, the large growth in foreign demand for our steam coal is now well recognized and documented. A major impediment in meeting this growing demand became abundantly clear in 1980. This impediment is the congestion existing at U.S. coal export ports. With the recognition of this constraint, a plethora of activity has been observed in announcements for alleviating the problem by improving and expanding current export port facilities. In addition to improvement and expansion, an abundance of totally new facilities has been announced in an effort to find ways to meet this large demand in the new business of steam coal export. This is needed; and hopefully, many of these plans will be translated into action. While total implementation of all stated plans is not expected, much of the implementation depends upon large- scale dredging, large waterside ground storage sites, and improved handling equipments in the conventional type of export ports. The time and capital required for implementation is great, and environmental problems associated with dredging are substantial. Host significantly, and unfortunately, implementation that does include dredging our ports will still not permit use of the truly large colliers of 140,000 DWT and greater, which are evolving as the "state of the art" in long-distance sea transport.

Jan 1, 1981

By A. J. Sinclair

Los métodos de desmuestre para estudios de viabilidad dependen de las características geológicas del yacimiento que ha de ser evaluado. Se requiere un estudio geoestadístico preliminar, teniendo en cuenta los aspectos de autocorrelación de las variables sometidas a estudio, con objeto de que el plan de diseño de muestras pueda ser optimizado para producir las estimaciones de ley y tonelaje dentro de los límites de errores establecidos. En general, debe de tenderse a una distribución regular de muestras para ello, y longitudes regulares de las mis¬mas (a partir de los testigos o cortes, por ejemplo) son preferidas con objeto de facilitar los análisis estadísticos. Los planes de desmuestre son modificados y mejorados (bien técnica o económicamente) a medida que avanza el programa y es obtenida información adicional. Las muestras a granel para pruebas metalúrgicas pueden ser evaluadas en término de va¬riaciones señaladas por todas estas muestras en un depósito y la variabilidad de la ley dentro de las mismas. Una atención adecuada sobre estas fuentes de variabilidad asegurará una evaluación adecuada de los resultados de las pruebas piloto de las muestras a granel. Por otro la¬do, un estudio mineralógico general del yacimiento es un requerimiento importante, a veces ignorado, en una evaluación más general pero semicuantitativa de la representatividad de una muestra a granel; y, además, proporciona una información muy útil para optimizar el diseño de la planta.

Jan 1, 1982

By G. Bulut, Ü. Yenial

"The use of recycled water in flotation has significant effects on flotation and selectivity because the recycled water contains many dissolved compounds and ions that alter the chemistry of the system. In this study, the effects of calcium, magnesium and sulfate, which are abundant components in recycled water, were investigated on galena, sphalerite and pyrite flotation using pure minerals and a complex sulfide ore by conducting bench-scale flotation, microflotation and zeta potential measurements. The bench-scale flotation tests indicated that higher recoveries of galena and sphalerite are obtained when water is recycled, due to higher concentrations of ions in recycled water. However, there was a critical ion concentration for galena recovery. The microflotation tests showed that galena recoveries at different pHs in recycled water are lower than in tap and distilled water. Pure sphalerite recoveries improved in recycled water in the bench-scale test with ore. Pure pyrite was depressed with recycled water as well. Zeta potentials became less negative with increased calcium and magnesium ion concentrations due to their adsorptions, and the presence of sulfate ions was seen to increase the negative charges of sphalerite and pyrite, conversely for galena. IntroductionWater is among the most important elements for mining and mineral processing. The distance to water sources is one of the major factors for mine site selection. The mining and mineral processing sector needs and consumes large quantities of water. In Chile in 2014, the copper mining sector alone consumed 12.7 m3/s fresh water for 1.189 tons of ore processing, and recycled 74 percent of the consumed water (Chilean Copper Commission, 2015). A plant that does not reuse or recycle any water will require 1.9 to 3.0 m3 of water per ton of ore processed (Gunson et al., 2012). Many stages of mineral processing, such as grinding, gravity concentration, dense medium separation, wet magnetic separation, flotation and hydrometallurgical operations, use large volumes of water (Schumann, Levay and Ametov, 2009).In mineral processing plants, the process water is recycled from the tailings dams, thickener overflows, and dewatering and filtration units. Wet concentration processes can require large quantities of water. Flotation, the most common process, typically takes place at 25 to 35 percent solids by mass. Most flotation plants practice at least some water reuse and recycled. Modern mines and mineral processing operations generally aim for zero water release (Levay, Smart and Skinner, 2001). In most cases, water quality has been found to affect flotation performance, and this interaction remains under investigation."

Jan 1, 2016

By F. H. Seymour

Central to Newmont Gold's Mine planning system is the ability to interactively perform cut and fill operations on topographic contours and to accurately evaluate grades and tonnages within contour outlines using polygon set manipulation routines. This paper develops the applied geometry concepts that underlie these routines. Included are representation of volumes with contours, point in polygon test, block proportion in polygon calculation, polygon area and centroid calculation, and intersection, union, and complement between polygon sets.

Jan 1, 1990

By M. P. Hoffman

The U.S. Bureau of Mines is developing a roof bolter with a computer-controlled drill head that will increase the safety of roof bolting in underground coal mines by allowing miners to be relocated to a safe area. To ensure secure anchorage, acceleration and strain data are broadcast from an instrumented drill steel to a data acquisition system. These data are analyzed, correlated, and transformed to pro-vide information about roof strata, then are sent to a supervisory computer executing National Institute of Standards and Technology's real-time control software. The supervisory computer sends setpoint commands to proportional-integral-derivative control loops to control drill thrust, position, revolutions per minute, and torque.

Jan 1, 1994