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By J. Restrepo, N. Ripepi

"The International Organization of Standards defines risk as “the effect of uncertainties on achieving objectives (15).” In mining, many uncertainties can influence the outcome of personal or professional objectives and are often difficult to predict. Risk management, the minimization and control of adverse effects from exposure to identified risks, is a well-established concept that can summarized as “being smart about taking chances” (12). Risk management now consists of management processes unique to numerous organizations across many industries, as varying sectors encounter a variety of needs, including the analysis and mitigation of risks related to physical security, product liability, information security, various forms of insurance, regulatory compliance, and workplace safety (12). The reoccurrence of multiple fatality events in the US mining industry, especially the underground coal sector, suggests an opportunity for improved methods of major safety hazard identification, assessment, and mitigation. A risk management approach would include ready identification and mitigation of these risks, inclusive stakeholder engagement, and rapid integration. While many solutions to reducing the risk of mine disasters have been proposed including stricter regulation and improved technology, a comprehensive risk management approach has yet to be fully integrated in the US mining industry. In December of 2006, R. Larry Grayson of the National Mining Association’s Mine Safety Technology and Training Commission called for “a new paradigm for ensuring safety in underground coal mines, one that focuses on systematic and comprehensive risk management as the foundation from which all life-safety efforts emanate (7).” A risk management approach has already been implemented with success in Australia’s minerals industry as part of a transition during the mid-1990s from a prescriptive based health and safety attitude to a more proactive, duty-of care [risk-based] philosophy (13, 16, 17).FUNDAMENTAL ELEMENTS OF RISK MANAGEMENT TECHNIQUES The fundamental components of a comprehensive risk assessment/management program are well-established within the realm of mining health and safety. Figure 1 depicts the elements of a typical mining hazard management framework. The first step in any safety-based risk management system is to identify and assess hazards by their location, nature, and magnitude within a mine. Next, a decision is made about choosing to eliminate, mitigate, or tolerate each hazard. Ideally, a hazard will be eliminated during the design stages of mining, though dynamic mining conditions often require continuous improvement and reevaluation of existing hazard controls. If elimination is not possible, hazard mitigation actions can consist of methods, rules, equipment, competencies, or other mechanisms. If a hazard is simply tolerated, as many inherent mining hazards must be, then specialized administrative controls must be utilized to minimize losses. During this process, the performance of each action is monitored and modified as needed (13)."

Jan 1, 2015

By T. P. Meloy

A methodology is presented for the spreadsheet solution of processing networks performing separations with the methodology developed here a spreadsheet grid is used to represent networks with and without recycle loops. In this manner, network solutions are numerically approximated by spreadsheet grid solutions. The methodology was used to explore the ramification networks developed by the Chinese for tungsten and molybdenum processing. Non-linear stage transfer functions for two-component sharp separations can be used.

Jan 1, 1994

By J. W. Mustard

The Macmillan Pass tungsten property (MacTung) is the largest known copper-tungsten, calcic, exoskarn deposit in the Western Hemisphere. Located on the border between the Yukon and Northwest Territories in northwestern Canada, the deposit crops out on Mt. Allen within the Selwyn Mountain Range. It was discovered in 1962 by a subsidiary of AMAX Inc. and has since been explored by 16,300 meters of surface and underground diamond drilling and by 800 meters of underground development. Geologic reserves are in excess of 30 million tons, grading slightly less than 1.0% WO3. Scheelite (CaWO3 ) is the main mineral of economic interest. Accessible by road, the property is not in production. Previously estimated reserves at MacTung have been unable to fully utilize all the geological controls on mineralization. In the past three years, however, an intensive program has been underway to improve our understanding of the deposit and to use the resulting information in a more precise way. This paper will discuss the key aspects of the geology as they specifically relate to reserve estimation and will demonstrate how these controls are being used in a geostatistical model of the deposit.

Jan 1, 1985

By B. Waterman, R. Collins, V. R. K. Paruchuri, P. Gonzalez, H. Dijkman

"INTRODUCTION Mining and processing of sulfide ore bodies has the potential to solubilize sulfate. Gypsum in the host rock, as well as oxidation of sulfides during milling and processing can solubilize sulfate. Acid rock drainage (ARD) also has the potential to generate waters high in sulfate. Even after treatment of the ARD with lime, the treated water can have sulfate present in gypsum saturation levels. Most mine-sites reuse sulfate impacted water but as a mine nears closure, reuse options may be limited and water treatment becomes an option. Furthermore, sulfate discharge requirements, particularly for anti-degredation narrative standards, can be very strict. Freeport has investigated many new technologies to economically remove sulfate from these types of water. A Dutch company, Paques B.V. developed one of these technologies and it utilized biological reactors to convert sulfate into elemental sulfur in a 2-step process. In 1992 the first industrial reference of the SULFATEQTM technology was commissioned at the Nystar Budel zinc refinery in the Netherlands. PILOT PLANT TECHNOLOGY AND DESCRIPTION As shown in Figure 1, the plant contains several process steps, which can mainly be divided into the following sections: 1. Anaerobic biological system in which sulfate is reduced to hydrogen sulfide by sulfate reducing bacteria. 2. Aerobic biological system in which hydrogen sulfide is oxidized to elemental sulfur by sulfide oxidizing bacteria. 3. Solid/liquid separation in which sulfur, calcium carbonate and biomass solids are separated and dewatered. Sulfate impacted ground water is pumped to the feed water tank through a plate and frame heat exchanger to maintain the solution temperature around 95°F. A custom mix of micronutrients is dosed to the feed tank. This nutrient mixture provides essential elements for the growth of anaerobic and aerobic biomass. Urea is added to the feed tank and provides the required nitrogen source to the biomasses. The pretreated feed water is pumped into the anaerobic reactor. The reactor works on the gas lift principle. Sulfate reducing bacteria utilize hydrogen gas as electron donors and reduce sulfate to hydrogen sulfide. This reaction increases the alkalinity of the solution. Carbon dioxide gas is added in order to control the pH within working range of the reactor. Due to the low solubility of the hydrogen gas, the anaerobic gas mixture is recycled through the system. The gas mixture recycle also provides the gas lift for mixing within the anaerobic reactor."

Jan 1, 2016

By C. Sampaio, C. Petter, M. Veras

"INTRODUCTION Use of sensor technology applied to the gravimetric beneficiation is intended for the selective preconcentration or separation of various minerals. Sensor Based Sorting (SBS) uses sensors to identify the particles and separate them by a mechanical process (flap) or pneumatic ejection valves (Wotruba et al. 2014). The principle of the SBS technology to separate mineral particles consists of three phases which cover feed,detection and separation. (killmann, 2009 Apud nienhaus et al. 2014). The applicability of the technique in an early stage of beneficiation enables free particles and poor grade to be a part of the process. The mass of tailings to be processed can be removed at the initial stage to save energy, water and equipment maintenance (Wotruba et al. 2014). Lindner (2010) suggested that the use of SBS technology would only will be possible if there exsists an electromagnetic interaction in all the wave spectra interacting with the solid ore. The interaction of electromagnetic waves depends directly on the characteristics of the material. The material receives a spectrum of electromagnetic waves by irradiation and this results in a reduced wavelength with differing types radiation such as fluorescence, reflection, remission, absorption, transmission and transmission. The frequency of the wave spectrum varies between 1000 and 1020Hz, illustrated by the data in Figure 1, which shows that each type of sensor emits a wavelength inversely proportional to the frequency ranging from 10-11pm to 104km, and the frequency that varies between EHz 103 and 1020kHz. The difference between the electromagnetic spectrum variations can only be visible to the human eye at wavelengths with intervals between 380nm and 780nm (Wotruba et al. 2014). One of the main advantages of operating with imaging sensors is the versatility of the images which can take on zero, one, two or three dimensions shown below as a point, a line, an area or a spatial image, as illustrated in Figure 2. According to Schubert (1988), to separate a mineral particle it is necessary to follow the characteristics of mineralogy, physics and chemistry with or without use of water. The use of new technologies can help reduce operating costs and improve utilization of mineral resources."

Jan 1, 2016

By J. Kemeny, K. M. Kim

A site-specific blasting model has been developed for the Asarco Mission mine. The main inputs to the model are the in situ block size (F80), the post-blast fragmentation (P80) and the intact tensile strength (To). The output from the model is the specific blast energy (ESE). Modern techniques are being used to obtain the input parameters for the site-specific blast fragmentation model. In particular, image processing software is used to obtain both the in situ block size and the post-blast fragmentation, and the Schmidt hammer is used to obtain the tensile strength at numerous locations throughout the rock mass. An initial model was developed using five test shots in an area of the mine that contains argillite and is relatively homogeneous. This process also included calibrating Schmidt hammer readings against actual Brazilian tensile measurements. The model for argillite will be updated as more tests are conducted, and the model will be extended to the four other primary rock types at the Asarco Mission mine.

Jan 1, 2011

By Mary Nelima Ondiaka, Kayode Henry Talabi, Oladunni Oyelola Alabi, Fatai Olufemi Aramide, Francis Gitau

Iron ore is essential in steel making; however, high-grade ores have diminished, making low-grade ores inevitable. These lowgrade iron ores need further beneficiation to upgrade the iron content. Currently, traditional physical and chemical methods are utilized and are not environmentally friendly. Bio-beneficiation techniques have emerged as a sustainable alternative for mineral recovery. This review delves into recent bio-beneficiation advancements for enhanced low-grade iron ore recovery using microbes. Research has revealed that bio-beneficiation methods such as bio-leaching, bio-flotation, and bio-flocculation have proven successful in iron recovery from ores. The bio-beneficiation process occurs in mild conditions using bio-reagents derived from microbes and offers a reduction of chemicals used in processing. Bio-beneficiation of iron ore potentially offers a relatively energy-efficient, cost-effective, and environmentally friendly method of maximum iron ore recovery. However, this review has identified a scaling-up difficulty in which a future approach for industrial-use applications is offered following a thorough sustainability assessment. Bio-beneficiation, using microbial processes, provides a viable avenue for maximizing iron ore recovery while tackling the constraints of dwindling high-grade iron ore resources and environmental sustainability.

Mar 16, 2024

By Emily Sarver, Cigdem Keles, Jonathan Gonzalez

The study re-examines respirable coal mine dust samples using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). It finds that SEM tends to overpredict the abundance of dust from rock strata and underpredict coal content, possibly due to coal-mineral microagglomerates (MAGs). The findings suggest that MAGs could be valuable in improving dust controls in mines.

Feb 10, 2022

By Dennis P. Bryan

Nevada is especially well endowed with industrial minerals, both in the number of ore deposits and the diversity of commodities. More than 600 significant industrial mineral deposits, containing 22 principal commodities, are present, in the State. The materials produced in Nevada in 1978 had a value of approximately 113 million dollars, and additional processing of some of them (e.g. gypsum into wallboard, limestone and clay into cement) added considerable more value. Table 1 shows the value of Nevada's industrial mineral production in 1978. Nevada currently supplies 85 percent of the country's barite producing 1.6 million tonnes (1.8 million short tons) valued at 30 million dollars in 1978. Nevada is second in diatomite production and contributes one-third of total lithium produced. Other industrial minerals being produced include clays, fluorspar, gypsum, lightweight aggregates, limestone and dolomite, magnesite and brucite, perlite, salt, sand and gravel, and silica. In general, Nevada produces high-value industrial minerals which are not consumed within the State, but rather, are shipped out of State. In contrast, most more populous states produce larger tonnages of lower value industrial minerals which are consumed chiefly within that state.

Jan 1, 1980

Geostatistics is well known as a tool for ore reserves calculations at the exploration stage. The goal of this paper is to show geoscatistics can also contribute to productivity gains, allow better selection of the mining methods and better control of the grades during production. The first two examples show how geostatistics can provide sophisticated models, using conditional simulations and the use of them for simulations or optimizations of mining processes. A third example will show how to use geostatistics for short term planning in a large polymetallic vein type mine.

Jan 1, 1983

By E. Ashworth

A thermistor probe has been developed to measure in situ temperature profiles underground. A full description of the probe is given. Data collected from the probe has been used to compare the actual profiles with those predicted from a finite element analysis using laboratory measured thermal properties of the different rock types. This comparison indicates the applicability of laboratory measured parameters in modeling the real conditions. Factors such as applied pressure, moisture content and anisotropy on laboratory measurements is discussed.

Jan 1, 1983

By Douglas G. Fox

Outputs from industrial activities planned in the Riley Ridge natural gas project are modeled to determine the potential locations of air pollution impacts on the Bridger and Fitzpatrick Wildernesses in Wyoming. The nature of modeling, especially with regard to its realism, is discussed. Alpine lakes which, along with their watersheds, have minimal buffering capacity are being studied because of their sensitivity to acidic deposition from proposed new air pollution sources. A hypothesis which relates a source's emissions to deposition and lake chemistry in a worst-case sense is presented. Research designed to test the hypothesis and reduce uncertainties is outlined and progress reviewed. Focus is placed on the meteorological transport and atmospheric deposition parameterization contained in the hypothesis.

Jan 1, 1984

By John B. Gustavson

Gold was first discovered in Alabama in 1830. Before a decade had passed more than 20,000 people were employed in the various gold districts scattered across east-central Alabama. By 1849 most of the presently defined gold districts were known with such towns as Arbacoochee, Chulafinnee, Goldville, Pinetucky, and Idaho being the principal mining camps. The California gold rush of 1849 signaled the end of intensive prospecting in the Alabama Piedmont for the precious metal. Reactivation of many of the old gold districts has been attempted several times since 1849. Significant activity and development took place between 1874 and 1880, 1888 and 1916, and 1929 and 1936. Locally, some of the development met with moderate succes. The last productive gold mine in Alabama ceased production in 1935. The sharp increase in gold prices since 1973 has caused renewed interest in the potential values of gold of the Alabama gold districts. Most of the gold workings have been abandoned for nearly 75 years and are for the most part inaccessible for convential property evaluation. The early gold miners and prospectors in Alabama were more intent upon finding and mining the valuable metal than in recording their activities for future generations. No matter how interesting or historically significant these records might have been the miners kept no records and left behind them few maps as clues to their activities. Inasmuch as most of the old gold districts have been extensively mined and prospected during the past 150 years, there is very little chance of finding large deposits through conventional outcrop prospecting methods. Similarly, the present geologic knowledge of the various districts is insufficient to launch successful exploration programs looking for large blind lode deposits in new locations within the general gold bearing region.

Jan 1, 1975

By Rollien R. Wells

The Bureau of Mines was created in 1910 by an act of Congress and subsequently directed to: "...conduct inquiries and scientific and technologic investigations concerning mining, and the preparation, treatment, and utilization of mineral substances with a view to improving health conditions, and increasing safety, efficiency, economic development, and conserving resources through the prevention of waste ..." Under this broad charter, the Bureau's responsibilities have changed and grown from an almost exclusive concern with coal and coal mine safety to the present emphasis on a full spectrum of mineral producing and consuming problems. In the past 30 years, the domestic consumption of coal, oil, gas, metals, and industrial minerals has more than quadrupled, in parallel with the rapid and enormous growth in industrial production. Of the scores of metals and nonmetals essential to the Nation's progress and security, many are scarce and difficult to wrest from domestic sources. Reserves of some ores are dwindling. Available ore resources are becoming leaner and more difficult to treat. In recognition of this many faceted problem, the Bureau has engaged in a continuing quest for new and improved technology to enable economic exploitation of marginal minerals and fuels, to find substitutes for minerals in short supply, and to create better materials to meet the expanding and diverse requirements of the growing economy. The current central concern of the Bureau is focused on meeting projected fuel, metal, and mineral demands at the lowest real cost by recovery from available resources by new and improved technology that minimizes waste, hazards, and social and environmental problems.

Jan 1, 1970

By G. Kemp Williams, Peter H. Dohms, Barry A. Hillman, Laurie A. Williams

Introduction In 1969, the US devalued the dollar. This action, over the ensuing four years, resulted in the deregulation of the price of gold. It also resulted in the rebirth of the US gold mining industry. The extreme inflation of the 1970s led to a dramatic increase in the price of precious metals. Consequently an increased interest in the exploration for and mining of gold has occurred. The enthusiasm began among the few existing producers who had survived on marginal profits during a prolonged period of fixed prices and constantly rising costs. Then came the newcomers. They saw the opportunity to enter an industry that historically had been characterized by small operations with low capital costs. It was not until the late 1970s that large mining companies recognized that investment in gold projects could generate cash flows that previously were associated only with world class deposits. Today, gold mining has tremendous appeal for the entire mining community, despite the dramatic price drop from 1980-81 levels. There are even major firms with no mining experience attempting to gain a foothold. But how easy is it to enter the US gold mining industry? What are the basic factors that influence the economics, and what are they likely to be for the remainder of the decade? How has the industry changed, and what is the composition of the active companies? An examination of the industry will help to answer these questions. US Gold Mining History The current gold rush is actually the fifth in the 208-year history of the US. The first recorded commercial mining of gold occurred in the Southeast in 1799. It produced from small, yet relatively rich placer deposits. The famous California gold rush of 1848 placed the US as a major producer with 62.2 t (2 million oz) of output by 1850. More than 93.3 t (3 million oz) was mined by 1853, equivalent to 63% of world production. But the richest placers were soon depleted. By the end of the Civil War, annual production had declined to well below 62.2 t (2 million oz). The government then relaxed prices and the industry again began to recover. The 1870-80s saw the great mines of the California Mother Lode and Grass Valley brought into production. This was followed by development of Nevada's Comstock, which later became one of the world's largest producers. Discovery of gold at Cripple Creek in 1892, coupled with technological advances in the use of large dredges in the California placers, resulted in significant production increases. And, with the expansion of the Homestake mine at Lead, SD, in 1898, US output again surpassed the 93.3-t (3 million-oz) level. By 1905, produc¬tion climbed to 124.4 t (4 million oz) with the addition of the Alaskan deposits, new output at Goldfields, NV, and the introduction of the cyanidation process. During World War I, the government forced the shutdown of gold mines. By 1920, total production had dropped to little more than 62.2 t (2 million oz). Many mines remained closed until the Great Depression. This, combined with the devaluation of the US dollar in 1934, resulted in a gold price increase to about $1.13/g ($35 per oz). Then began the fourth gold rush. By 1937, output had again surpassed 124.4 t (4 million oz). This was due to an increase in primary production and new byproduct production from base metal operations. Unlike the previous period of growth, however, this period was short-lived. The imposition of Executive Order L-208 in 1942 once again forced the shutdown of most mines. At the end of World War II, cumulative US gold production had

Jan 12, 1984

By Gerald H. Luttrell, Seyed Hassan Amini, Aaron Noble

One of the most important processing engineering tools for designing mineral processing facilities is linear circuit analysis. This technique, originally conceived and developed by Meloy, Williams, and Fuerstenau nearly four decades ago, provides fundamental insights regarding how unit operations interact and respond when arranged in multi-stage processing circuits. Researchers have successfully utilized this tool to improve the operating performance of industrial processing circuits incorporating coal spirals, magnetic separators, mineral spirals, and eddy current separators. More recently, advanced versions of this tool have also been developed to provide a standardized framework for circuit mass balance calculations, to output exact analytical solutions to mass yield and value-based efficiency expressions, and to estimate uncertainty propagation in separation circuits. This article reviews the historical development of linear circuit analysis, describes how the technique has evolved to address more complex circuit design problems, and presents industrial case studies that highlight the importance of this process engineering tool.

By R. D. Call

During the past fifteen years considerable progress has been made in the technology of slope design. It is possible to design rational slope angles if suitable data on geology, hydrology, and rock properties are available. It is of course preferable to conduct a full scale slope design study, but there are those situations where a full scale study is not feasible because of time and budget constraints. In this paper we will treat two situations: (1) choosing slope angles for a preliminary feasibility study at the exploration stage; and (2) dealing with a slope failure in an operating pit. In these instances slope angles must often be chosen on the basis of available or readily obtained data. In an exploration program all too often a feasibility study is initiates just a few months prior to the decision deadline to drop the property or to exercise an expensive purchase option. If all that is available at this point are a few cross sections at odd angles showing ore and waste contacts and a dog-earred map of the surface geology there may not be time to collect and organize enough information for design of slope angles. On the other hand if during the drilling program geologic cross sections are constructed and the structural data is presented in tabular form, rational slope angles can be determined within the allotted time. Certain types of data can be collected only at specific times during a project. Two prime examples are logging fracture intensity and collecting samples for rock testing before the core is split. It is particularly disheartening to ask to see the core and to be shown a tattered cardboard box filled with plastic bags of sample pulps.

Jan 1, 1976

By Shani Engelbrecht, Belinda McFadzean, Avuyile Wali, Natalie Shackleton, Vratislav Malysiak

Frothers play a crucial role in sulphide and PGM ore flotation recovery, and AECI Mining Chemicals studies on PGM ores have shown significant flotation kinetic increases with the optimal frother-collector combinations. Using Senfroth 200 as the industry baseline, remarkable kinetic increases were observed with AECI Mining Chemicals developed frothers in the first concentrate. Even in the worst-case scenarios, 4E PGM recovery increased by 5% at a slightly higher concentrate grade. It is important not to limit frother dosage to a fixed value. Instead, enough frother should be added to maintain a stable bench float, measuring the dosages by frother volume before and after tests. Frothers can be specialized blends and their importance should not be underestimated. The results produced by formulating and innovating frothers to address specific industry challenges have been encouraging. Testing a frother on a plant scale does not have to be as daunting as with collectors, enabling the identification of the best frother-collector combinations at an industrial scale. AECI Mining Chemicals bench scale testwork has motivated plant-scale trials that have successfully transitioned to commercialization. This paper compares the results from metallurgical and froth stability tests and shows that occasionally frothers that have a less stable froth can have improved valuable mineral recoveries, while still exhibiting better drainage for reduced entrainment and mass pull. It was shown that caution should be used when relying only on simplified froth stability tests in the evaluation of new frothers.

Feb 1, 2025

By Dean H. Herrick

The production of crushed stone in the United States has exceeded 1.0 Gtpy since 1987. Eighty percent of the crushed stone produced is used in the aggregate industry, accounting for over half of the quantity of natural aggregate consumed in the United States. Approximately 718 of the crushed stone produced in 1989 was limestone and dolomite followed by granite, traprock, sandstone and quartzite, miscellaneous stone, marble, shell, calcareous marl, volcanic cinder and scoria, and slate in order of descending volume (Table 1). Of the remaining 20% crushed stone produced in the United States and not used as aggregate, 12% is used in the manufacture of cement which is an important construction material. Only 8% of crushed stone is used in specialty products not associated with the construction industry. Therefore, this chapter will concentrate on crushed stone as used in aggregates, with occasional reference to other uses or to chapters which discuss specific nonconstruction uses of crushed stone. Construction aggregates are hard, essentially inert materials suitable for being formed into a stable mass by the addition of cementing or binding materials that produce a concrete by compaction, or by natural weight to produce a road or foundation fill. Aggregates are usually from 80 to 100% of the material volume of the construction masses in which they are used. Conditions necessary for a rock deposit to be developed for construction crushed stone include: Quality-should pass rigid specifications for strength and durability; Quantity-adequate volume of rock is needed to have a production life of at least 10 years, preferably 20 or more years; Market-must have adequate market to support a new crushed stone operation; Transportation-transportation cost must be competitive for the intended market; Environmental-the impacts of mining, processing and transportation of crushed stone on the environment at or surrounding the mine site must be within acceptable limits; Permitability-mining, processing and transportation of crushed stone must usually be permitted by governing agency. The following discussion will touch upon all facets of crushed stone operations from the mineral deposit and its geology to technology, uses, economic factors and end with governmental regulations of mining crushed stone. The sections are not designed to answer all questions, but rather to be an introduction to the crushed stone industry. Where more information is required, The Aggregate Handbook by Barksdale (1991) is recommended as the best general source.

Jan 1, 1994

By R. J. Weege

Conventional underground mapping methods and diamond drilling are being applied in a study to determine the nature of the copper ore occurrences near the footwall of the Osceola lava flow top, commonly referred to as the Osceola Amygdaloid. Our work to date suggests that structures formed by relatively impermeable barriers, created by flowage and injection of still-molten lava from the interior of the flow into the solidified, brecciated crust, acted as the ore receptacles. Ascending hydrothermal fluids traveling near the footwall contact were trapped and confined in these barriers which retarded the direct upward movement of the ore fluids and caused deposition of copper. Oreshoots located near the footwall appear to have been formed spatially' independently from the hanging-wall oreshoots by fluids traveling simultaneously, but along different channelways. The barrier concept as advanced by earlier writers to explain the concentration of the ore-bearing, fluids into broad shoots con¬stituting entire ore bodies is found to be equally as applicable for the localization of smaller oreshoots within the Osceola ore body.

Jan 1, 1962