Search Documents

By Evan Bennett

ALMADEN is Arabic for "the mine." The definite article is properly used, for no mercury mine in the world compares with it for richness and volume of ore, produced and potential. After more than twenty centuries of exploitation, intensive throughout the last lour, ore from Almaden is about five times as rich as that of its closest competitor. We drove to the mine one April afternoon, across Don Quixote's plains of the Mancha, up the bleak, arid valley of the Rio Valdeazogue where we passed tenth century Moorish workings and their ruined castles. At dusk, we came to the Hacienda de Castilseras, a large farm where Almaden miners work their land on off days. Then we drove through the whitewashed, well-ordered town to the Castillo de la Direccion where we were challenged at the iron gate by two picturesquely costumed Guardias Jurados.

Jan 1, 1948

By W. F. Watts

This report describes a statistical analysis of 41,502 respirable quartz dust samples collected from 1974 through 1981 in metal and nonmetal mines and mills. The goal of this Bureau of Mines study was to identify commodities and occupations associated with high quartz dust exposure so that future enforcement and research activity can be focused on the high-exposure areas. For this analysis, the Bureau used its computerized Mine Inspection Data Analysis System (MIDAS), which contains data on nearly 350,000 air samples, including data for 61 contaminants in 45 commodities. The samples analyzed were collected by inspectors of the Mine Safety and Health Administration (MS HA). The data were entered into the MIDAS computer and coded according to commodity, occupation, location, and other categorical information. Occupations an. commodities with high quartz dust exposure were identified by grouping the data by code categories. Workers at sandstone, clay and shale, and miscellaneous nonmetallic mineral mills had the highest quartz dust exposures. Within these mills, occupations with high exposures were baggers, general laborers, and persons involved in crushing, grinding, and sizing operations. Dust concentrations in these mills were not necessarily the highest, but because the dust contained a high percentage of quartz, the health risk from dust exposure was the greatest.

Jan 1, 1984

By S. Koski

The Cerro Verde copper-molybdenum porphyry mine, majority owned and operated by Freeport- McMoRan Copper & Gold, is located 30 km southwest of Arequipa Peru. The concentrator, which produces copper and molybdenum concentrates, started operating in late 2006 with a 108,000 tpd design capacity, processing primary sulfide ore (mainly chalcopyrite and molybdenite). Plant capacity was recently increased to 120,000 tpd. The comminution circuit consists of one 60? x 113" primary crusher, four MP-1000 secondary crushers in closed circuit with dry screens, four 2.4m x 1.6m High Pressure Grinding Rolls (HPGRs) in closed circuit with wet screens, and four 7.3m x 11m gearless ball mills in closed circuit with cyclones. The HPGR circuit is fed by the Secondary Crushing circuit product at a T80 of 35 millimeters, and the HPGR circuit product feeds the Ball Mill circuit at a T80 of 3000 microns. This paper describes operating experiences with HPGRs during these first four years highlighting improvements in operating practices and presentation of data regarding operational efficiencies, also discussed are the primary benefits provided by HPGRs such as production of micro fractured particles, reduced ore Bond Work Index, and reduced power consumption. Cerro Verde represents the first installation of HPGRs in both the copper industry and large scale hard rock mining.

Jan 1, 2012

By Taner Aydogmus

The A$29 billion Chevron-operated Wheatstone Project is one of Australia’s largest resource projects. Located at Ashburton North, 12 kilometers west of Onslow in Western Australia, the project will consist of two Liquefied Natural Gas (LNG) trains with a combined capacity of 8.9 million tons per annum and a domestic gas plant. The LNG Plant will serve the offshore gas fields, which are situated some 250 km off the coast of Onslow in Western Australia. Once operational and on-stream, the Wheatstone Project will contribute to Australia becoming the world’s second largest exporter of LNG. For crossing the environmentally sensitive shore area, a micro-tunnel with an internal diameter of 2 m and approx. 1,242 m in length has been constructed by means of the pipe-jacking method. The micro-tunnel will accommodate a 1.1 m diameter pipeline (trunkline) to deliver gas from the offshore fields LNG Plant. The Wheatstone shore crossing design involves a number of unique challenges owing to its coastal location, where the alignment crosses through a shore area and terminates in a marine environment. This paper provides an overview of the Wheatstone Shore Crossing Project, presents the key features, and discusses the main aspects of the micro-tunneling design.

Jun 13, 2021

By Paulo José Costa Couceiro Junior, Manuel Lopez Cano

In 2011, two historic outcrop rocks known as Teffé and Itapema located in the navigation channel of the Port of Santos, Brazil (Latin America’s largest port) – were excavated by drilling and blasting techniques. Sensitive structures - a passenger terminal and an 80-year old warehouse were exposed to ground vibrations generated by underwater blasting. The warehouse had existing structural problems due to a combination of factors such as the presence of an unstable soil, previous repair work, and intense seismic events generated by the daily traffic of cargo trains nearby during eight decades. Since the worsening state of the structure was attributed to ground vibration from underwater blasting, particle velocity time histories generated by underwater blasting and by passing trains were monitored. By analyzing the energy spectral density of these events using spectrograms, it was possible to observe the seismic energy levels in time and spectral domains. Since the hysteretic energy dissipation by structures is related to the duration of the seismic event and the limited dissipation capacity of the structure, one could expect damages to appear in the structure once energy levels exceeded this dissipation capacity. As the quantity of energy transmitted to the structure is proportional to the duration of the seismic event, the transmission of seismic energy to the warehouse structure over time was more significant in the case of the train-induced ground vibrations (several minutes) than those generated by the underwater blasting (few seconds). Thus, for the warehouse, train-induced ground vibrations have a larger impact on the structure rather than ground vibration generated by controlled underwater blasting techniques.

Jan 1, 2016

By Jonathan J. Dewsbury

It is argued that approximate computer based methods are only suited to modelling conventional piled rafts, for pile enhanced rafts where the interactions will be non linear three dimensional finite element analysis is required. However current 3D finite element analysis often relies on symmetry to reduce computational cost and there are concerns over the dependency of the results on the user. Therefore a new strategy within the finite element framework has been proposed. The main advantage of this strategy is that each stage of the model can be checked for consistency. There is also the added benefit that non symmetrical models can easily be constructed by tying the validated components together without dramatic increases in computational time. The proposed strategy compared well to the published results of a hypothetical example of a piled raft previously analysed with numerous methods by Poulos et al. (1997).

Jan 1, 2010

By Maria I. De Rosa

The U. S. Bureau of Mines performed experiments to determine if the primary gas toxicities evolved during the early (~300° C) and later (~400° C) combustion stages of chlorinated polyester-reinforced mine ventilation ducts could be predicted by a smoke particle characteristic, for the development of a test parameter. The experiments were conducted in an approximately 20-L furnace, at 14-min durations at set furnace temperatures of 2500 and 1,000° C, with an airflow through the furnace of 10 L/min. The variables studied, as a function of time, were the hydrogen chloride (HCI), carbon monoxide (CO), carbon dioxide (C02), and oxygen (02) concentrations, furnace temperatures, the sample mass weight loss, the average smoke particle diameter (dg and average number and concentration (no), and the product of the average smoke particle diameter and concentration (dgno). Results show that the inverse of the smoke particle diameter-concentration product [(l/dgn0)], correlates directly and significantly with the primary gas toxicities evolved during both early (HCI) and later (CO) stages of combustion.

Jan 1, 1989

By Zhang Chuanfu

The fibrous nickel oxide powder was prepared by the method of chemical precipitation and pyrolysis, that is, the NiO precursor was firstly precipitated from nickel ions solution with addition of oxalate salt and then the final NiO powder was obtained by pyrolysis of the prucursor. The effects of the pH, reaction temperature, reactant concentration, addition of surfactant on the morphology of the precursor particles were investigated. The influences of the various conditions, including the temperature and time, the air flow and the speed of the temperature increase on the morphology, average size and specific surface area of the NiO particles were also addressed. The fibrous NiO particles with IOO~ 120 in axis/diameter ratio and 5.5 m2/g of the specific surface area may be produced under certain operation conditions by this process.

Jan 1, 2003

By B. DANIEL MARJAVAARA, I. A. SOFIA LARSSON, ANNA-LENA LJUNG

The flow field and coal combustion process in a pilot-scale iron ore pelletizing kiln is simulated using a computational fluid dynamics (CFD) model. The objective of the work is to investigate how the thermal effects from the flame affect the flow field. As expected, the combustion process with the resulting temperature rise and volume expansion leads to an increase of the velocity in the kiln. Apart from that, the overall flow field looks similar regardless of whether combustion is present or not. The flow field though affects the combustion process by controlling the mixing rates of fuel and air, governing the flame propagation. This shows the importance of correctly predicting the flow field in this type of kiln, with a large amount of process gas circulating, in order to optimize the combustion process. The results also justify the use of down-scaled, geometrically similar, water models to investigate kiln aerodynamics in general and mixing properties in particular. Even if the heat release from the flame is neglected, valuable conclusions regarding the flow field can still be drawn.

Apr 20, 2021

The history of the discovery and development of the Kambalda nickel orebody. is reviewed and the decision to process the Kambalda concentrates by the Sherritt-Gordon process at Kwinana is discussed. The Kwinana Nickel Refinery is described and the problems encountered in the first year of operation are Outlined.

Jan 1, 1971

By Frank E. Williams

This Bureau of Mines report deals with the urbanization of Tucson, Ariz., a southwestern city with an arid environment. Zoning regulations concerning known aggregate sources are described, and information relating to projected needs for the urban area is furnished. History of growth is outlined not only for the local aggregate industry, but also for the entire urban area. Past conditions are pointed out and background material for future conditions is provided.

Jan 1, 1967

By John Kruse, Sethu Raman, Dave Tenney

The Cullaton Lake B-Zone gold mine was the first gold producer in the Kaminak Subprovince of the Canadian Shield . Located approximately 650 km north of Thompson. Manitoba, the mine produced 77,783 ounces of gold and 5,564 ounces of sil ver from 251 ,236 tons of ore during 1981-84 period. The depos it is a small , structurally controlled , stratabound orebody in an Archean iron formation. Most gold occurs in sulphide and silicate fac ies. Based on new ev idence, the depos it is interpreted to have fo rmed by remobilization of syngenetic low-grade gold mineralization in the iron fo rmation in a favoura ble fold structure. The concept and methods developed at the mine have been successfull y applied in the discovery of new deposits in the area. One of the concepts. which link Archean and Proterozoic mineralization. may have wider applications in the search fo r gold deposi ts elsewhere in Canada .

Jan 1, 1986

By Kingman, Robert I.

SUFFICIENT testing has been .performed with the Dutch State Mines Cyclone for thickening and desliming flotation feed at the concentrator of the National Lead Co., Tahawus, N. Y., to prove its application for this work. It is the purpose of this article to present some of the test results, operational details and advantages of cyclone thickening and classification. The metallurgy of the mill operation was described by Frank R. Milliken, assistant manager of the titanium division.

Jan 1, 1950

Never known as a conference to shy away from its share of off-color jokes, the Colorado Mineral Processing Division?s Annual Meeting returned to the Broadmoor Hotel in Colorado Springs, CO April 26-28 for its 62nd edition, this one held under the theme ?Does size matter (is bigger always better).? With the predictable jokes sprinkled in here and there, and a few unpredictable ones as well, the three-day conference featured a healthy mix of talks about some of the latest technical developments in the field of mineral processing, as well as insightful looks at some new operations in the western United States. This year, the Colorado MPD also launched the Wagner Equipment Student Scholarship program.

Jan 1, 2012

By George F. Becker

(San Francisco Meeting, October, 1911.) A MERE record of Emmons's professional career would very inadequately represent the man. That he was eminent we know, and our successors will realize in due time; but they must depend upon us for knowledge of a singularly wholesome, modest, unselfish personality, and of a character that did honor to a profession in which trustworthiness is indispensable: Those members of the Institute who met Emmons are his friends, and I never knew one of these who was not the better for that friendship. Emmons was born in Boston, Mar. 29, 1841, the son- of Nathaniel H. and Elizabeth (Wales) Emmons, and was named Samuel Franklin after an ancestor who was of the same family as Benjamin Franklin. He took the degree of Bachelor of Arts at Harvard in 1861, and soon afterwards went abroad to complete his education. From 1862 to 1864 he attended the courses at the École Impériale des Mines at Paris, lie e Beaumont and Daubrée being among his professors. The year 1864-1865 he spent at Freiberg under Cotta and other famous teachers; after which he spent another year in traveling through Europe. Like many other renowned geologists, he approached his ultimate profession from its economic side, and was thus from the first imbued with a sense of high responsibility in the promulgation of scientific opinions or conclusions. With hypotheses which were interesting merely because. they were ingenious or even plausible, he would have nothing to do. In 1867 he joined the Geological Exploration of the Fortieth Parallel at its organization under Clarence King, serving at first as a volunteer, but soon receiving a regular appointment. This expedition was the first one of purely geological character sent out by the United States Government. As Emmons has shown in his admirable presidential address on " The Geology of Government Explorations," its work was founded on a com-

Sep 1, 1911

By Walter Pajalich

This Bureau of Mines report is a study of the organizational framework of the ferrous scrap industry, of the products produced, and of the factors affecting the consumption of ferrous scrap by the steel industry. Consumption data from 27 major iron and steel firms in the States of Illinois, Indiana, Iowa, Michigan, Minnesota, and Wisconsin during the period between 1957 to 1962 were grouped by type of iron and steel furnace production facilities to determine consumption pattern for various grades of scrap in comparison to ingot production, hot metal consumption, and home scrap generation. Grades of scrap affected by changes in scrap consumption were determined, and the pattern that emerged was analyzed. Correlation of scrap demand and its effects on scrap prices based on price of scrap receipts of No. 1 heavy melting scrap and No. 2 bundles in the Chicago area for the years 1957 through 1962 indicated that demand trends do not always affect the price of scrap, Past and present technological advancements in steelmaking processes are discussed, and their effects on the scrap industry are analyzed.

Jan 1, 1967

By S DeKruijff

The Mount Isa Mines Copper Mine in Mount Isa started producing copper in 1966. The Copper Mine gradually increased production rates to nearly six million tonnes per year. Over the last three years the mine has been in a gradual ramp down due to the reduction of primary ore sources and head grade. The majority of ore sources are predominantly in pillar retreat sequences bounded by multiple fill masses. There also a substantial lower grade resource delineated to the south of the main orebody. These remaining ore sources present significant engineering challenges to obtain a safe and cost-effective extraction. Stope designs have become increasingly complex and require additional engineering and operations input and analysis. This paper describes the major planning and operational challenges and issues associated with the stope design and extraction of an orebody in the later stages of mine life.

Jan 1, 2000

Objective: On-the-job training (OJT) is a common means of training workers. By definition, it seems relatively simple. However, to be effective, training must go beyond the simple process of following an experienced worker around the workplace— sometimes called the "follow Joe" method. NIOSH researchers spoke with human resources personnel, safety and health specialists, supervisors, experienced miners, and new miners and found that OJT was of high interest, but was rarely part of a formal or standardized program. Various training methods have evolved to ensure that a trainee will absorb the information presented rather than simply emulate what the instructor is teaching. These methods have been brought together into a published guide for developing an effective formalized OJT program. The guide (Information Circular (IC) 9479) is called "Coaching Skills for On-the-Job Trainers." It contains materials and suggestions for your company or mine to conduct a 1-day workshop for teaching OJT trainers how to be better coaches to less experienced workers. The guide was created by the NIOSH Pittsburgh Research Laboratory and a safety professional from a private mining company.

Feb 1, 2006

By Krishna R. Reddy, Jyoti K. Chetri, Girish Kumar

Geotechnical engineering encompasses a major portion of the civil and infrastructure projects. The large amounts of energy and resources typically used in these projects leads to undesirable emissions and wastes which contribute substantially towards global environmental impacts (e.g., global climate change). This could further include secondary economic and societal issues which are often unaccounted in traditional engineering design of the geotechnical projects. In order to address this issue, it is imperative to integrate the broader environmental, economic and social implications into decisions of a geotechnical project. Recent years have seen a major impetus on life cycle assessment to evaluate the environmental sustainability of the geotechnical designs. However, there are no tools that can quantify the life cycle triple bottom line sustainability of potential design alternatives in a project with holistic considerations towards broader economic (indirect costs and benefits) and social impacts (stakeholder preferences, socio-environmental and socio-economic impacts). This study presents a new framework for quantitative assessment of life-cycle sustainability (QUALICS) for alternative designs in engineering projects. The framework integrates two multi-criteria decision analysis methods namely, the Integrated Value Model for Sustainable Assessment (MIVES) and Analytic Hierarchy Process (AHP), to support decision making on the potential design alternatives. In this study, a brief overview of the framework is presented. A case study demonstrating the use of QUALICS framework is discussed with its application to the sustainability assessment of two deep foundation systems, caissons and piles, over their design life. The technical designs of both systems are developed based on bearing capacity, both primary and secondary settlements, and structural integrity. The results from the sustainability assessment of the two deep foundation systems are discussed, and the most sustainable option based on different stakeholder preferences and site-specific conditions are identified.

Jan 1, 2019

By P. P. Rosario, D. M. Maijer

The primary crusher is a key component in the comminution process applied in open pit mines. A collaborative research project between the University of British Columbia and Highland Valley Copper (HVC) was conducted aiming at understanding gyratory crusher liner wear in the overall context of the crushing process. This paper presents an analysis methodology applied to data collected using a laser-based tool for assessing wear in gyratory crushers. Data from the wear measurements was correlated with crusher production information such as current draw and throughput. As a result of the knowledge developed during this work, an innovative way to evaluate crusher liner profiles was created and new mantle profiles were designed. This led to a reformulation of HVC’s standard liner management policy with a resulting estimated annual savings of 13% in total crusher liner cost and a 15% reduction in liner replacement downtime.

Jan 1, 2006