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By T. P. McNulty

During the last decade, many exhaustive studies have been made of process energy requirements for the production of various metals and materials. Some excellent technical papers and text books have resulted, and some of these are included in the bibliography of this paper. These studies were, of course, prompted by the economic pressures which resulted from the beginning of the "Energy Crisis" in 1973. Our intensified consciousness of the cost of energy led, then, to a greatly improved understanding of the energy consumption attributable to individual mining, processing, and refining steps. It is worth noting, however, that an awareness of the cost of energy is not new and that efforts to minimize this cost were an important part of sound mine and plant management practice throughout the earlier days of our industry. One only has to read a few accounts of mining operations around the beginning of this century to develop an appreciation for the cost of supplying wood, coal, fuel oil, or electric power to remote locations.

Jan 1, 1983

By S Schwarz, D Alexander

The mining industry, and in fact the world, has undergone significant changes in the past five to ten years, ranging from the metals boom, the global financial crisis and the rise and fall of national economies, to name just a few. There has been a focus on sustainable development for projects and operations in the mining industry, mainly pushed onto the industry by communities, governments and other agencies. While sustainable development and operation is a worthy priority for mining operations, discussions with mining industry personnel (with a strong slant on the mineral processing perspective) have shown other issues have surpassed the typical issues of water resources, energy availability and the environment. These include staff turnover and skills shortages, extracting metal from more complex orebodies and the uptake of new step-change technology.A number of key operating mineral processing personnel were interviewed to determine their perspective on the current issues facing the mining industry. This paper details the findings of this survey and highlights some of the topics that have been identified as the top issues from a mineral processing perspective.CITATION:Schwarz, S and Alexander, D, 2012. Current issues in the mining industry - From the operational mineral processorÆs perspective, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 369-372 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By E. Yigit

Hydrometallurgical production of zinc from concentrates is generally carried out by H2SO4 leaching. For the smooth operation of this process, some harmful components must be removed from the leach solution before the electrolysis stage; MgO is one of these compounds. Zinc concentrate samples from the Mount Isa mines were used in leaching tests. Leaching tests with an aqueous solution of H2SO4 and SO2 gas were carried out at various temperatures, pH levels and leaching durations. While duration and the pH value of the solution were effective parameters in H2SO4 leaching, temperature and pH were more effective in SO2 leaching for the removal of MgCO3 and CaCO3. Removal of MgCO3 and CaCO3 was generally achieved at low pH values. The results show that SO2 gas can be a good alternative to sulfuric acid in the leaching of MgCO3 and CaCO3

Jan 1, 2010

By James B. Pfeiffer

TETRA Technologies, Inc., has applied its HDS? metals precipitation system to control a mine drainage problem. The effluent from the mine contains primarily zinc, manganese and iron, plus varying small amounts of cadmium, copper and lead. The flow from the mine averages 350 gpm, and varies considerably depending on season and weather conditions. The plant was designed to treat 1000 gpm of the water and generate a dense sludge suitable for recycling. The HDS? system contains a number of reactors, followed by post filtration and meets stringent metals discharge criteria as specified by New Source Performance Standards.

Jan 1, 1994

By T. A. Griffin

Gentlemen: The subject of this paper is: ADVANCED APPLICATIONS OF BUCKET WHEEL EXCAVATORS AND RECLAIMERS. Against an urgent world wide energy crisis, the role of bucket wheel excavators and reclaimers in the surface mining of fossil fuels and other ores has been raised to new prominence. This paper will review the reasons for the expanded application of bucket wheel technology, its unique contributions, and other factors relative to volume, cost, versatility, and efficiency. Today, surface mining is faced with the twin challenge of (1), accelerating the rate of removal of massive quantities of overburden and ore, and (2), replacing comparable high volumes of overburden back into the mined-out portion of the pit. Optimum quantitites for - a single electrical power plant now range from 5 to 15 million tons of coal per year. The use of bucket wheels offers the best method for meeting this challenge at lowest possible cost. For example, an advanced application that also satisfies environmental concerns involves the simultaneous functioning of two bucket wheel excavators during surface mining operations. Working at spaced intervals and different levels in conjunction with a transfer conveyor and stacker, one excavator removes the ore while the other one transfers overburden to a stacker that replaces it back into the open pit. The result of this continuously operating cycle is: (1) removal of ore and replacement of overburden back into the pit in massive quantities, (2) at accelerated volume and extreme low cost that cannot be matched by conventional loading machines of any size, and (3) fulfills a basic environmental requirement which is to

Jan 1, 1974

By Jeramy B. Decker, Paul H. Madsen

"During the excavation of the north bound tunnel of the Devil’s Slide Tunnel project, deformation (convergence) was measured after passing through Fault Zone B. The tunnel convergence was not symmetrical, but was larger on the left side of the profile. It was determined that a shear zone nearly parallel with the tunnel drive was contributing to the uneven deformation. This paper will discuss how it was determined that the shear zone existed and how multi-point borehole Extensometers (MPBX) were used to verify that a significant amount of the deformation was occurring due to movement along the shear zone as the excavation was advanced. In addition, performance of the shotcrete liner in the area of the convergence will be examined. Finally, the paper will consider the means and methods that were utilized to ultimately control and stabilize the deformation. INTRODUCTION The Devil’s Slide Tunnel Project consisted of excavating two 1,250 meter tunnels each with a profile of 80 m2 utilizing the New Austrian Tunneling Method (NATM) or otherwise known as the Sequential Excavation Method (SEM). The tunnels are part of the California Coastal Highway south of Pacifica, CA, a suburb of San Francisco. The tunnels were opened to traffic in March of 2013. Geological Setting The tunnels run north-south through the San Pedro Mountain ridge, which is part of the Santa Cruz Mountains. The tunnel lies within the San Andreas Fault system and is 7.2 km west of the surface trace of the San Andreas Fault and 2.8 km east of the surface trace of the San Gregorio Fault. The 10 km strip between these two faults is referred to as the La Honda structural and terrain block (Decker et al. 2010; Amini et al. 2005; Earth Mechanics Inc. 2003). Locally, the tunnel passes through three blocks representing different geological conditions: South Block, Central Block, and North Block (Figure 1) (Decker et al. 2010; HNTB Corporation et al. 2005). The South Block consists of Mesozoic aged granodiorite and quartz diorite. The South Block also contains many local shear zones and a low angle thrust fault (Fault A). The South Block ends at Fault B, which is the southern border of the Central Block."

Jan 1, 2016

By W. A. Cole

As the mines get older and the active workings get Farther and farther away from the original mine openings, it becomes increasingly difficult and expensive to ventilate most coal-mines properly. At the same time, the avenues of escape for those employed underground have become so extended' as often to make it impossible for them to make their way out of the mine in the event of a fire, mine explosion, or other emergency. Where such Conditions exist, the only satisfactory solution is to make new ventilation and emergency-escape openings near the active mine workings. At most mines this would necessitate sinking shafts, which is often slow and expensive.

Jan 1, 1945

By A. D. Misener, L. G. D. Thompson

"IntroductionIt was shown by work previously reported that reliable geothermal gradients representative of various regions of the earth's, surface could he obtained from extended surveys of the rock temperatures in operating mines. These surveys showed the presence of anomalies in the isothermal levels and the existence of regions of regular behaviour. Below about 3,000 feet the temperature gradients became quite regular over the areas stud1ed. It is these regular gradients which are taken as representative of the region, wherever possible.The present paper describes the extension of this work which was undertaken to obtain further temperature gradients with a view to correlating them to other geophysical properties determined for the same regions. The additional data obtained have indicated possible reasons for the temperature anomalies. The experimental procedure was similar to that already described and was again made possible through the wholehearted co-operation of the management and the assistance of the personnel of the mines concerned. The research was entirely supported by a grant from the Research Council of Ontario.The equipment was a distinct improvement over that previously used and made it possible to take many more accurate temperature readings in a given time. Thermistor resistance thermometers were used, encased in silver sheaths and protected against damage by heavy copper casings. These were calibrated with a standard platinum resistance thermometer.The bridge used with these thermometers was one of a number designed and built by the Meteorological Service and designated M.S.C. Thermometer Indicator Type C-3. This very convenient and portable instrument operated from batteries in the instrument case. Multiple thermometer connections were provided so that rapid readings• of a number of thermometers was possible to accuracy of the order of 0.1°F. All electrical connections on the panel are covered with Dow-Corning ignition compound to prevent; electrical leakage due to moisture condensation. This, together with the high resistance of the thermometers and components of the bridge, gave much more reliable results than previously obtainable."

Jan 1, 1950

By W. B. Xie

The hardening behaviour and microstructure evolution of Cu-30Ni-30Mn alloys aged at 350 °C has been investigated utilizing optical microscope, scanning electron microscope, transmission electron microscopy and Vickers hardness tester. The results show that the discontinuous precipitation of NiMn phase results in a remarkably hardening effect in Cu-30Ni-30Mn alloy during aging at 350 °C. The maximum hardness (~494HV) is attained in the sample after aged for 48 h. The NiMn precipitates are ordered and have a face-centered tetragonal structure. The coherent orientation relationship between the NiMn precipitates and Cu matrix is (220)Matrix // (220)P, [1-1-2]Matrix // [1-1-2]P. In addition, there is a linear relationship between hardness and volume fraction of the discontinuous precipitation, which indicates that the hardness increment of Cu-Ni-Mn alloys aged at 350 °C is attributed to the microstructure characteristics of discontinuous precipitation. The high strength of discontinuous precipitation colony is caused by the formation of nanoscale NiMn precipitates with a lamellar structure in discontinuous precipitation. INTRODUCTION Cu-Ni-Mn alloys are attractive candidates for oil drilling, aerospace and energy applications due to their high elasticity, high strength and excellent corrosion resistance (Sun et al., 2009; Liu, Yang, Xia, Jiang, & Gui, 2016). The high strength of the Cu-Ni-Mn alloys is mainly attributed to the precipitation of NiMn phase (Shapiro, Tyler, & Lanam, 1974; Xie et al., 2015). The uniformly dispersed nanoprecipitates formed by continuous precipitation can impede dislocation movement, and thereby lead to a significant improvement in strength of traditional precipitation-strengthened alloys. However, it is reported that there are two precipitation types observed in Cu-Ni-Mn alloys, namely, continuous precipitation and discontinuous precipitation (Shapiro et al., 1974). The discontinuous cellular colony with a lamellar structure nucleates at grain boundaries, and progressively grows inward the grain on the process of discontinuous precipitation (Ng, Bettles, & Muddle, 2011). It is found that the discontinuous precipitation can occur in many Cu-based alloys, such as Cu-Ni- Mn alloy (Shapiro et al., 1974), Cu-Be alloy (Monzen, Hasegawa, & Watanabe, 2010) and Cu-Ni-Sn alloy (Zhao, & Notis, 1998). Many studies consider that the discontinuous precipitation results in a detrimental effect on hardness and strength, and the discontinuous precipitation occurring during aging treatment should be suppressed (Markandeya, Nagarjuna, & Sarma, 2004; Semboshi, Sato, Iwase, & Takasugi, 2016). The mechanical properties can also be improved by discontinuous precipitation in AZ91 magnesium alloy (Tamura, Kida, Suzuki, & Soda, 2009) and AM30 magnesium alloy (Saikawa et al., 2012). Jun (2017) found that the reduced interlamellar spacing of precipitate fibers in discontinuous cellular colony leads to a significant increase in hardness. Indeed, the strengthening contribution of discontinuous precipitation is similar to that of continuous precipitation in Cu-20Ni-20Mn alloy. Discontinuous precipitation of NiMn phase can provide a significant strengthening effect in Cu-Ni-Mn alloys.

Jan 1, 2019

By P. R. Taylor

Titanium carbide and titanium diboride powders have been successfully synthesized by direct treatment of ilmenite concentrates in a non-transferred arc thermal plasma reactor. Methane gas was used as the reducing agent and boron oxide was used as the boron source in these processes. Free energy minimization plots were used to predict the behavior of each system under different molar ratios and operating conditions. Products were characterized by XRD, SEM and chemical analytical techniques. The average size of the ceramic product is in the submicron range. Metallic iron apparently is finely deposited on the surface of the titanium carbide or titanium diboride particles. Minor impurities such as silica, manganese and zircon were converted to the carbide form.

Jan 1, 1995

By N. Arbiter

Evidence for the floatability of sulphide minerals without collector is analyzed and it is shown that results obtained with ores, in contrast to those with single minerals or mineral mixtures, depend on many additional variables, some identified and others not. Because of the prevailing low levels and costs of collectors for most sulphide ores, it is unlikely that collectorless flotation will have commercial applications, so that continued research on the subject may be justifiable on theoretical but not on practical grounds.

Jan 1, 1993

By Benjamin Cebrián, María Gil, David Flores

In many occasions during the Mining operation life, blasting engineers find different and controversial results of fragmentation, dilution or wall control for the same geotechnical domain and blast design (pattern and explosive charge). Most of the times, the difference between same blast designs is not measured, not controlled. Once a blast designed is defined, the most important part of the process after that is the implementation of every step of the blast on site. Almost nobody is measuring it, controlling it, but just controlling implementation is possible to relate blast design with results in a consistent way, to optimize the full process of D&B. Controlling implementation not only per event but also to check and change trends and decision-making is paramount for optimization and saving millions of extra costs every year. The lack of resources and the hardness to manage all the info created every day in a blast make this process very tough and difficult to maintain in long term. The use of new technologies on site and software that allows a best, more consistent and continuous control of blast implementation have been proved to be the key for optimizations and cost saving. This document shows the evolution of drilling and blast digitization process, savings and trends in a mine, using new technologies that creates business opportunities and general improvement of D&B process.

By A. D. Davis

The Bear Butte Creek watershed, in the northern Black Hills of South Dakota, shows the effects of past mining activities in the form of dissolved metals and arsenic in stream water. Bear Butte Creek, during normal flow periods, loses all of its discharge to sinkholes that recharge the Madison Limestone aquifer. This work focused on the geochemical transport and fate of arsenic and on understanding ground-water flow conditions in the Madison aquifer through development of a three-dimensional ground-water flow model that was coupled to a geographic information system (GIS). Stream sampling and discharge measurements helped determine sinkhole losses and loading rates. Column laboratory tests provided data on arsenic adsorption and the mixing of stream water with aquifer water, which also was simulated with the geochemical models, pHREEQE and NETPATH. The models and GIS can be updated with new information and will be useful in managing the water quality of the Madison aquifer.

Jan 1, 1997

By Alessandro Boscaro, Daniele Martinelli, Cristina Gabriela Oñate Salazar, Daniele Peila, Carmine Todaro

"The wear phenomenon in TBM machines is not a simple issue, as many parameters are playing an important role on the consumption of the tools during a tunnel excavation. The action of the wear due to the contact with the soil can occur on the excavation tools, on the cutterhead, in the excavating chamber and on the screw conveyor. The test developed at the Laboratory “Tunnelling and Underground Space Center” of the Politecnico di Torino is aimed to reproduce the interaction between the tools and the excavated material, simulating the excavation conditions in terms of soil conditioning and water content. The test, which is not standardized, is studied to evaluate the wear in a global point of view. The present work starts by testing the influence of the use of chemical agents during the conditioning phase on the drop of the wear phenomenon, in terms of metal weight loss. 1. INTRODUCTION The wear phenomenon of the excavation tools used in TBM tunneling machines is playing recently a major role in the design stage of full-section tunnels in both soils and rocks. Concerning EPB excavation technology, the main issue regarding productivity is the wear of its components (Peila et al.,2012), which increases the so called dead time in the whole process. The friction generated between the components and the ground causes the consumption of the tools and other metallic components in contact with the ground, described as primary and secondary wear by Nielsen et al. (2006a). This leads to downtime, with risky and complicated maintenance operations (Peila and Schulkins, 2009), as occurred in recent tunneling works in Liguria (Italy). The study of this argument in granular soils is very delicate, as it encloses not only the properties of the excavation tools, but also the characteristics of the ground to be excavated (hardness, mineralogy composition, shape and dimension of the particles and moisture content). The penetration mechanism is based on the scraping of the ground, by mean of cutting tools, with its consequent consumption. Concerning the rocks, the excavation principle is characterized by crushing the rock mass matrix by applying high compressive stresses through cutting disks. In such a way, to avoid frequent downtimes and their consequent economic losses, it is very important to study this subject and therefore understand and forecast the durability of the components, in order to try to maximize the productivity of the machine by reducing the frequency of maintenance stoppings."

Jan 1, 2016

By G. W. Jones

An important activity of the Bureau of Mines is the promotion of safety in mining and industry. As a part of this program, the Bureau determines the explosion hazards of combustible gases, vapors, and solids and investigates means of controlling and preventing explosions. The limits of inflammability (explosive limits) of combustibles are not only of theoretical but also of practical importance, because many industries at one time or another contend with explosive mixtures of combustible gases or vapors in their manufacturing processes. At present many new organic compounds are being manufactured, transported, and used in huge quantities which a few years ago were only laboratory curiosities.

Jan 1, 1941

By A. David Miller, Douglas M. Barber

"The Rocky Mountain Arsenal was used by the military to produce chemical warfare agents and incendiary munitions for use during World War II and later by private companies for the production of industrial and agricultural chemicals. After an investigation performed in accordance with CERCLA confirmed significant levels of contamination due to the common industrial and waste disposal practices of the era and the discovery of over 300 species of wildlife inhabiting the land the Rocky Mountain Arsenal became a wildlife refuge and contamination cleanup efforts began. Three lime basins originally used to treat wastewater from the chemical production were decided to be contained in place, requiring a seepage barrier installed around the perimeter of the site to further prevent groundwater/contaminant migration. This case study will discuss the successful installation of a soil-bentonite cutoff wall around the area using deep soil mixing. Highlights of this case study will also include a discussion of the challenges faced due to construction activities performed with Level B Hazmat PPE requirements as well as added challenges brought on by the Winter season, after the project was delayed due to a positive air monitor detection for the chemical weapon Lewisite during construction of the work pad.INTRODUCTIONThe Rocky Mountain Arsenal (RMA), located just outside of Denver, Colorado, was established by the United States Army in 1942 to produce chemical warfare agents and incendiary munitions for use during World War II. Following the war, and as weapons production decreased, portions of the site were leased to private companies for the production of industrial and agricultural chemicals. The principal lessee, Shell Oil Company, manufactured mostly pesticides at RMA facilities from the early 1950s to the early 1980s.In 1984 an investigation began in accordance with the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) and confirmed significant levels of contamination due, in large part, to the common industrial and waste disposal practices of the era. It was also discovered that over 300 species of wildlife inhabited the land in the absence of regular human activity, including a group of bald eagles, leading to the passing of the Rocky Mountain Arsenal National Wildlife Refuge Act in 1992."

Jan 1, 2015

By T. A. Penzov

As a result of recent scientific and experimental studies new technical devices have been developed for monitoring and control the process of grinding. The description of microprocessor module MILLCONT 1 for control of the loading of the mill and microprocessor density control module DENSIMETER is given in the paper. The improved variant of the automatic system for ore grinding control in single-stage ball mill working in close cycle with a classifier with above mentioned technical means is shown in the paper. The loops for measuring and stabilization of the basic technological parameters (density of the ready pulp ? and fineness of grinding of the pulp ß) are described in the paper. The nowadays economic results in ore grinding process automation are given as well.

Jan 1, 2014

By Evgenii Pavlov, Ivan Tronin, Viktor Timofeev, Vladimir Kislov, Sergei Bogovalov

"Modeling of the magnetohydrodynamical (MHD) and thermodynamical processes during the industrial scale Direct Chill (DC) casting of aluminum slabs is performed using a combination of ANSYS/CFX and ANSYS/EMAG software. The electromagnetic field is modeled through ANSYS/EMAG, while hydrodynamic and thermodynamic processes are modeled through ANSYS/CFX. Both packages were modified in order to calculate MHD flows in the liquid pool that forms during aluminum DC casting, and they were unified into a software combination that provides simultaneous simulation of all the above processes. The simulation shows that the electromagnetic stirring of the molten aluminum changes the shape of the solidification front (solid-liquid interface) very dramatically, namely it becomes significantly flatter. This effect should improve the internal structure of aluminum DC slabs and allows us to increase the casting velocity.IntroductionProduction of Aluminum alloys with high mechanical properties and structural uniformity is one of the main goals of industry. The preferred production method of aluminum alloys in most modern plants is Direct Chill (hereafter DC) casting because it offers high productivity and commercial success. One important limitation of this technology is the development of centerline shrinkage in slabs larger than about 1 meter. The improvement of the internal structure of long DC cast slabs can be achieved by electromagnetic stirring (hereafter ES) of the liquid metal above the solidification front. This intensifies heat transport in the zone close to the solidification front and suppresses shrinkage formation."

Jan 1, 2013

By V. Z. Kozin, E. A. Bekchurina, P. S. Volkov, Yu. P. Morozov, A. S. Komlev

"The current sampling systems of ore flows or concentrates are based on the method of cross sections in point sampling and the method of scooping in reducing. The limited number of point samples in sampling and microsamples in reducing lead to big random and probable systematic errors. The paper defines the principles of sampling, which assure the absence of systematic errors and also provides calculation formulas of probable errors in sampling methods of cross and longitudinal sections as well as in samples preparation. The article sets the fundamental laws of sampling: the dependency of minimal mass of gross sample and number of point samples from mass of point sample in sampling from heterogeneous body; the dependency of a sample minimal mass from lumps’ size in preparation of carefully mixed samples; the dependency of point samples’ dispersion from duration of control period. The paper introduces the fundamental notions: lump variance; probable systematic error; methodical error. It also provides a solution of outstanding sample correct application in analysis results calculations. In application of automatic analyzers, mounted in material flows, the probable error connected with sampling, is calculated by the formulas for carefully mixed sampling bodies. The paper describes the developed and introduced sampling systems on the base of combined application of cross and longitudinal sections methods in sampling and preparation of samples. The advantages of this equipment are compactness, reliability, simplicity in service and operation, and for pulps it is adaptability in pipelines. Application of the developed equipment entirely excludes probable systematic error. The new systems of sampling and preparation of samples are introduced at 25 concentrating plants. Introduction of the developed systems at sampling balance points of concentrating plants allowed double reducing balance deficiency."

Jan 1, 2018

By Chikabumi Yamauchi, Mitsuru Tanahashi, Jutaro Miura, Takaharu Iwadachi, Toshiharu Fujisawa

"Tue oxidation behavior of molten Cu-Be alloys was investigated by exposing· the molten Cu-Be alloys to various Ar-O2 atmospheres to control the oxygen partial pressure, PO2 = 10 ~105 Pa at 1423 K. The following results were obtained:• The oxygen · partial pressure in gas phase affects the morphology of the oxide formed on the surface of the alloy and · the oxidation rate of beryllium.• At lower oxygen partial pressure, a molten Cu-Be alloy is covered with a homogeneous and compact internal layer of BeO. Thus, the beryllium oxidation rate can be minimized.• By adding a small amount of calcium or zirconium into the molten Cu-0.5 mass% Be alloy, a protective BeO layer is formed even at higher oxygen partial pressure. Thus, the beryllium oxidation rate can be reduced.IntroductionCopper-beryllium (Cu-Be) alloys are well recognized for their unique properties, such as high electrical conductivity, high strength, high fatigue strength, excellent properties at elevated temperatures, good formability and good corrosion resistance. .This extraordinary collection of properties are the reasons why Cu-Be alloys are expected to be ""Key-materials"", which are necessary to further advance science and technology and to be applied in.various fields such as electronic devices, machine parts, repeater housings of undersea optical fiber communication cables, etc.However, a large amount of beryllium is oxidized to BeO in melting stage of the current Cu-Be alloy production process, because beryllium is a highly reactive element. This is one of the ·main factors that negatively affect the production yield and th_e product quality."

Jan 1, 2000