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By W. M. Colwell

When it comes to the analysis of gold bearing ore, there are literally dozens of variables that contribute to the final "true value" of a given sample. Initial sample selection, splitting size and method, inherent nugget gold, pulverization method, and analytical method variations are but a few. However, it seems that the inherent nugget gold particle is targeted as the primary reason for intra and inter-laboratory variations in assay. The following study will show that this is not always the case. A series of tests were undertaken for the Aurora Partnership-Aurora Project to solve inter-laboratory variations in the analyses of blasthole cuttings. Initial concern was centered on the probability that free gold occurrence was resulting in erratic results for the mine's cyanide shake assays and outside laboratory fire assays. Comparison of fire assay and cyanide shake assay was sporadically consistent with previously demonstrated extraction percentage for the cyanide method. The goal was to delineate the factors that ensure consistency in analyses; implement, where needed, Good Laboratory Practices; and reestablish acceptable analytical method correlation.

Jan 1, 1993

By Robert J. Russell

The importance of grinding as a unit operation in all industry has caused much effort to be expended toward improving the facility with which grinding can be done. Endeavor has continued nearly 100 years to formulate laws governing crushing and grinding. This has not been without controversy. However, grinding is an experimental science and our useful knowledge originates in experience. The recorded experience is grinding history. Today, many types of size reduction equipment, each with variations, are available to industry. Frequently, more than one type of grinding equipment will meet a requirement of grinding. However, an economic evaluation of installation and operating costs generally indicates a preferred type. The selection of grinding equipment requires' a consideration of the purpose in grinding, the characteristics of the material to be ground, equipment available for grinding, and the manner in which it can be applied best.

Jan 1, 1960

By Earl M. Frizzell

This paper addresses considerations for the use of artificial support of pit walls in surface mines, a new project of the Bureau of Mines. Results to date indicate that a polymer-coated cable with embedded grit could provide good anchorage for stabilizing benches and highwalls, and an electronic method of recording discontinuities in the field is being reviewed and developed for application to mining. The objectives of the work in progress are to define the engineering parameters and evaluate the concepts for artificial supports in order to provide safe working environments when pit slopes are steepened to increase ore recovery and reduce overburden handling.

Jan 1, 1986

By I. M. Stewart

In a proposed rulemaking regulating asbestos, nonasbestos varieties of Tremolite, Anthophyllite and Actinolite would be excluded from the regulations controlling permissible exposure to asbestos fibers. This proposed rulemaking is perceived as improving the scientific basis of the regulation of asbestos because it recognizes that there are no scientific data, either mineralogical or health related, which support the regulation of nonasbestos Tremoiite, Anthophyllite and Actinolite in the same manner as asbestos fibers. However, the proposed regulation, while representing a major advance in the treatment of AT A for regulatory purposes, does not provide an adequate analytical method for distinguishing between asbestos and nonasbestos particles, nor an adequate description of the regulated minerals. This paper addresses those topics, recommending that OSHA include an appropriate mineralogical definition, and implement a discriminate counting procedure to distinguish asbestos from nonasbestos particles.

Jan 1, 1992

By B. C. B. Pretorius

A heat load analysis of the very hot sub-shaft area of Loraine gold mine situated near Welkom, South Africa, showed. that the heat that needed to be removed to give acceptable wet-bulb temperatures at the working faces could not be done by the normal ventilation air alone, but would have to be complemented with extensive refrigeration. The paper outlines the considerations in selecting the cooling system adopted for this shaft.

Jan 1, 1980

By Edward A. Vitunac

The emerging importance of pneumatic conveying systems for bulk materials is becoming recognized by more persons responsible for materials management as consultants, at the corporate level and at the plant level. They have learned that the economic advantages of a pneumatic system are frequently decisive when compared to alternate methods. Included in these advantages are relative simplicity, ease of installation, flexibility, ease of maintenance, cleanliness, safety and ease of automation to the degree desired. In general, installed costs favor a pneumatic system when compared to competing mechanical systems if the transporting distances are long or to and from many points. In addition, supplemental use such as cooling, heating, or drying may supply the incremental value required to justify its selection. (1). The main disadvantages of a pneumatic system is the greater horsepower required per unit weight of material conveyed and material limits in abrasiveness and density. In addition, there is a tendency to increase material breakage at changes of direction and at any obstruction such as the imperfect butting of one, piece of pipe to another in the conveying line. Classification of the material at the discharge may also cause problems in dusting and segregation. Materials weighing less than 4 pounds per cubic foot tend to cause feeding and collecting problems although they can be conveyed easily. Material between 4 and 20 pounds per cubic foot can be handled with less problems but flow rate is hard to predict. The 20 to 60 pounds per cubic foot range offers best results; whereas, over 60 pounds per cubic foot, materials tend to drop out of the air stream and settle in the pipe line unless careful provisions are made to prevent it. (2).

Jan 1, 1967

By Glenn L. Krum

Inflation has received much attention due to its effect on capital budgeting, associated cost overruns, and declining real profits. This study focuses on the effects of inflation on the evaluation of a mining investment and the estimation of a mining project's revenues. The study indicates that the best method for estimating future returns is the fore- cast dollar scheme. In this scheme, the metal price was held constant, and the operating costs were "inflated" along a historical regression line. The conclusion was reached by comparing the "actual" performance of a 3000 tpd (tonnes per day) lead mine model with 'its estimated performance during four time periods (1950-1960, 1955-1965, 1960-1970, 1965-1975). The individual data files for each time period and estimating method (6 files by 4 time periods) were pro- cessed by a suite of cash flow computational and investment analysis sub- routines. The analysis presumed that the mine was part of a large corporation which could utilize the expensed, development and exploration costs and any investment tax credits, in the year that they were incurred.

Jan 1, 1979

By J. M. Rios

This paper exposes the reasons that led the Empresa Nacional Minera del Sahara, S.A. (ENMINSA) to the selection of a conveyor belt system for the transport of phosphate rock over a distance of 100 kilometers. ENMINSA was created in 1962, with the main objetive of the exploitation of phosphate rock deposits in the Spanish province of Sahara, in North West Africa. Poor grade outcrops were known previously. A detailed geological research carried over the province led ENMINSA to the discovery of deposits not exposed, and of much higher grade. The sector known as Bu-Craa was chosen as the most promising, and was explored by means of drill holing and shafting. The important amount of information obtained permitted a detailed evaluation of the capacity and grade of the rich ore contained in the Bu-Craa area. Simultaneously with the systematic reconnaissance of the Bu-Craa deposits, ENMINSA developped the study of the technical and economical problems required for the beneficiation of the rock, which comprised five main groups of projects: rock exploitation; beneficiation plant; rock transport from the mine site to the Atlantic coast; storage, handling and loading facilities by the sea- side, and power plant. Once determined the location of the marine loading facilities, which to date are in an advanced stage of construction (figs. 1 and 2), the studies conductive to the selection of the best transport system from the mine to the ocean, along 100 kms. distance were undertaken.

Jan 1, 1968

By Naoko Shimazaki, Andre Xavier

Over 10 million tourists have visited Vietnam in 2016. Travel and tourism accounted for 9.3% of the country’s Gross Domestic Product (GDP) in 2014. At the same time, as with many other resource-rich developing countries, Vietnam has been developing its extractive resources sector as a means of promoting the country’s social and economic development. In 2015, mining was the third largest contributor to GDP, and accounted for 8% of Vietnam’s gross domestic product. Vietnam is the third largest mineral producer in SE Asia. Although it produces zinc, nickel, bauxite, and manganese, coal mining is its most developed sector. The country has over two hundred coal mines, and total reserves of approximately 6 billion tons. Quang Nihn Province, where the World Heritage Site Ha Long Bay is located, is a very important tourism destination. It is also a coal-rich region where mining extraction and processing have been active since the early 20th century. Vietnam is signatory of the United Nations Sustainable Development Goals (SDGs). The country is aware of the importance and the challenges involved in managing the extractive sector in a way that does not undermine its tourism industry and yet that contributes to the country’s sustainable development. To this end Vietnam is taking actions towards implementing more advanced coal-mining extraction and processing techniques. The country is furthermore promoting a responsible mining sector, and is investing in programs that foster environmental protection and sustainable tourism. This paper examines the case of the Ha Long Bay region and the project involved in relocating the Hong Gai coal preparatory factory from a seafront area to a mountainside area. This paper provides a preliminary review of the initiatives adopted by the government of Vietnam to address the existing challenges that have resulted from a focus on promoting the country’s socio-economic development through the exploration of its rich coal endowment. Furthermore, it also describes Vietnam’s legal and policy frameworks. In conclusion this study identified that Vietnam has drafted a National Action Plan to implement the Sustainable Development Goals. The country is also taking an integrated approach to implementing the SDGs agenda and that it is assigning responsibility to a variety of ministries to achieve SDGs’ specific targets. Furthermore the country is changing policies and the legal framework in order to facilitating the execution of the work of agencies that are responsible for implementation, regulation and enforcement. In this respect, the approval of the National Action Plan on Sustainable Development Goals is another important step in that direction. While the decision of supplying its internal market with high quality coal helps minimize negative environmental impacts in Vietnam, exporting low quality coal to other countries does not help resolve the problem of CO2 emissions globally. With respect to the 2030 Agenda, this may be considered a temporary solution since to achieve the SDG goals, Vietnam will have to consider other sources of cleaner energy in order to align with the Sustainable Development Goals # 7 on affordable and clean energy.

Jan 1, 2017

The US Constitution provides for regulation by the states for protecting the public's safety, health, and welfare. Hence, in the eyes of the law of all states today, this is the sole justification for registration of professional engineers. Wyoming was the first state to register professional engineers in 1907, to correct abuses of incompetent or fraudulent practices in surveying and real estate. Public safety and health are most directly affected by civil, electrical, and mechanical engineering. Other branches of engineering have a profound effect on the public welfare, including investors, and safety and health of employees. No arguments, pro or con, are valid except in relation to the registration laws of various states. Code of Ethics Few would argue the desirability of requiring conformance with a code of ethics. A major problem lies in enforcing compliance, since protecting the public demands a high standard of competence, yet assessing competence gets confused with restraint of trade. Bidding engineering work on price competition can lead to pressure to cut corners on engineering quality, and was therefore discouraged by codes of ethics. The Supreme Court, in a suit against the National Society of Professional Engineers (NSPE), barred any engineering society from such bidding restriction. It has, however, upheld the right of states to impose codes of acceptable practice as part of registration laws. For example, Texas Canon I reads, "The engineer's paramount professional responsibility should be the safety, health, and welfare of the general public." Anything less makes the code practically meaningless, but there are potential conflicts of interest in many engineering organizations. How can conflicts be handled? Any corporation could improve its public image by adopting a policy that each employed PE should, without fear of recrimination, record in writing over his seal any problem or flaw in any design that comes to his attention. The policy should further require that his superior provide him a written reply pointing out that the "flaw" is accepted as requiring correction or as a calculated risk, or overruled as erroneous or as a difference of opinion. Errors in calculation of judgment are inevitable. Despite this, there are limits to how much time and money should be spent to eliminate them. It is difficult, however, to see any excuse for failure to conscientiously evaluate the opinion of a PE. This may be an impossible ideal, but how else can the profession or the industry have credibility? The National Council of Engineering Examiners (NCEE) has a code of ethics one presumably subscribes to by signing an application to write a Principles and Practices examination. However, NCEE has none of the power of enforcement that is available through state boards of registration. Registration Qualifications Qualifications are set by the laws of the states. In general, they require passage of an eight-hour examination in fundamentals, preferably at graduation, and, later, one in principles and practices. The examinations are compiled and distributed by NCEE. This system provides for a high degree of uniformity and reciprocity. States set the education and experience levels (typically four years after graduation) required by those desiring to write the principles and practices examination. Examinations The principles and practices examination calls for answering eight of 20 equal weight questions; one on engineering economics, 19 on engineering. Economics may enter into engineering questions, but only provided the question is not answerable by an economist without engineering training. In preparing examinations, NCEE strives to use questions that require some judgment and can be more effectively answered by someone with four years experience beyond college. The aim is to assess entry-level professional

Jan 2, 1984

By Jonathan M. Pachter

The Bailey mining complex is located in Greene County, PA in the valley of Talley Run, a small stream tributary to the Enlow Fork of Wheeling Creek as shown on the location map insert found on Figure 1. The Bailey complex includes two Pittsburgh No. 8 Seam deep mines (Bailey and Bailey #2), a coal preparation plant, and two refuse areas (for disposal of coarse and fine processing waste). Clean coal is shipped from the complex via a 24.15 km (15 mile) rail spur, which connects to the Monongahela Railroad in Waynesburg, PA. In early 1981, Consolidation Coal Company (Consol) began a permitting effort aimed at beginning construction of Bailey, the largest underground coal mining complex to be built to date in the United States. Construction of the Bailey Mine began in December, 1981, less than six (6) months following the first application submittal. Clean coal was produced by the Bailey Preparation Plant in September, 1984. Effective project planning, including early formulation of a project planning team, identification of "red flag" issues, innovative responses to environmental questions and development of environmentally sound project designs, all contributed to the relatively quick permitting at Bailey.

Jan 1, 1985

By T. A. Farr, I. A. Gibbs, F. Guevara, S. R. Simms, G. Nojima

This paper describes an installation of a medium-voltage adjustable frequency motor drive (AFD) on a high starting torque regrinding mill. This type of application is typically found in the mineral industry dealing with hard ore. The AFD electrical architecture is introduced from line to load. The type of closed loop encoder feedback motor control algorithm is briefly described. The results of the AFD motor identification auto-tuning are compared against the manufacturer’s supplied data. The motor drive performance results are shown for pre-ramp DC fluxing, high starting torque with overload current, excessive load torque stall condition, and blocked rotor. The instrumentation and arrangement for the two watt-meter method to capture low frequency data are presented. The data shown is from the input power quality meter, the AFD computer tool, the output motor protection relay, an oscilloscope, and load shaft connected strain gauge (rotating telemetry for torque assessment). These types of high starting torque constant torque loads are found in mining and process industry applications employing AC adjustable frequency drives. Using field results should help demystify the use of voltage matching output transformers in AFD applications including constant torque loads

Mar 2, 2022

By J. M. Rotter, R. A. Lohnes, J. Y. Ooi

Reliable prediction of wall pressures in a coal silo demands careful characterization of the stress-strain properties of the coal. This paper describes the results of triaxial compression tests on a typical fine-ground coal used in power generation and describes the fitting of several different constitutive models to the data. The fitted parameters for the constitutive models are well suited to application infinite element analyses. The different models are used to give the reader flexibility in choosing a model and to show the shortcomings of some models. To explore the quality of the fitting process, the fitted results are compared with finite element predictions of the triaxial test itself.

Jan 1, 1998

By A. G. Journel

The indicator random function formalism allows a common coding of hard numerical data, constraint intervals, and soft qualitative information as prior probability distributions. The soft kriging algorithm allows interpolating these priors into posterior probability distributions of the unknown. The curse of ?negative kriged grades? is solved. The consideration of additional soft information, whenever deemed necessary, becomes possible within the framework of well-proven kriging techniques.

Jan 1, 1986

By K. V. Raj, T. Bhowmick

"Computational fluid dynamics (CFD) modeling of an open-pit mine has several challenges. A good quality mesh of the model domain is a pre-requisite for convergence in solution. Good quality tetrahedral meshing and insertion of prism layers in faceted open-pit mine geometry is complicated due to presence of numerous vertices and ridges. Presence of vertices and ridges result in poor quality tetra elements and holes in prism layers, which cause instability in the model. Good quality pit bottom prism mesh elements significantly improve the formation of velocity boundary layer and thermal boundary layer at the pit bottom. This results in an expected temperature dependent micrometeorological buoyancy flow in the pit. Whereas, model geometry without a prism layer, results in abrupt temperature gradient near pit bottom. Buoyancy flow and recirculation have significant effect in lifting mechanism of fugitive dust particles generated near pit bottom. Representative initial and boundary conditions and selection of appropriate turbulence model have significant influences on the simulation results. In this paper, three-dimensional models of open-pit mines are developed using commercial CFD software (CRADLE-CFD). Important constraints and various consequences in modeling complex open-pit geometries are presented. INTRODUCTION Application of Computational fluid dynamics (CFD) to model an open-pit mine to predict fugitive dust and pollutant concentrations in and around a mine is relatively new. In former Soviet republic (USSR), Baklanov [1] and Belousov [2, 3] presented numerical models of pollutant transport in open-pit mines in Arctic regions. In recent years, advances in mathematical and computational fields have enabled better modeling of pollutant dispersion phenomenon around mines using computational fluid dynamics (CFD). Several CFD software packages have been used by various researchers to model the pollutant transport in open-pit mines. Works by Alvarez et al. [4]; Lowndes et al. [5]; Silvester et al. [6]; Torno et al. [7]; Choudhury and Bandopadhyay [8]; Collingwood et al. [9]; Raj et al. [10] and Flores et al. [11]; are examples of application of various commercial and open source CFD packages (COMSOL, ANSYS, OpenFOAM) to model pollutant transport in open-pit mines. These researches provided a strong background for additional research involving CFD modeling of open-pit mines. Due to the limitations of computational times and capacity, 3D modeling and various aspects of fugitive dust dispersion in open-pit mines remained unexplored."

Jan 1, 2015

By C. G. Treworgy

Geologists at the Illinois State Geological Survey are evaluating geologic and land use conditions that affect the minability of coal to determine how much coal is available for development using current technology and mining practices. Coal resources are being evaluated for selected 7.5-minute quadrangle study areas. In a central Illinois study area, more than 25% of the deep-minable resources were limited from development by unstable roof conditions resulting from thick unconsolidated sediments overlying thin bedrock overburden. In some southern and southeastern Illinois study areas, geologic conditions associated with a paleo-channel limit the minability of significant resources of low-to medium-sulfur coal. Some features which were thought to limit mining, such as areas of closely-spaced oil wells, have been found to have minimal impact on the amount of coal recovered.

Jan 1, 1995

By T. A. Gray

There are several potential large-volume uses for coal ash in mining-related applications that could be environmentally and economically beneficial to mining companies. Actual usage, however, may be constrained by regulations or by perceptions of coal ash and the potential uses. To identify currently allowed uses and to assess constraints to coal ash use in the eastern coal fields, questionnaires were sent to state coal mining agencies to determine their policies on coal ash utilization and to mining companies to solicit their viewpoints on coal ash utilization. Identifying and understanding the constraints will allow for the development of a coordinated and consistent approach to remove or reduce these constraints and possibly allow for increased utilization of coal ash by the mining industry. This paper summarizes the findings of our investigation.

Jan 1, 1995

By K. A. McDonald

This paper will describe the experiences of Hibernia Holdings, Inc. in constructing a mineral processing facility in Mexico. It will attempt to set forth a guideline on what companies attempting to operate in Mexico can expect and what actions they can take. Ownership laws, import/export laws, labor laws, security, transportation and operating experiences will be discussed.

Jan 1, 1994

By C. Huang, S. Lin, Y. J. Wang

Introduction A mine characteristic curve is of great importance for both theoretical analysis and daily management of a mine ventilation network. Ventilation engineers are well acquainted with the ways of obtaining and using a mine characteristic curve that is conventionally associated only with single-fan networks. However, for a multiple-fan network, difficulty has long been recognized in defining the curve, not to mention, obtaining or using it. To extend the concept of mine characteristic curves for a multiple-fan network, a subsystem-based approach has been introduced by Wang (1992a). He defines a subsystem characteristic curve for a multiple-fan network and discusses the numerical procedure for constructing the curve. A graphical method of obtaining a subsystem characteristic curve for serial-parallel, multiple-fan networks has also been accomplished (Wang, 1992b). In spite of the maturity of the fundamental concepts related to and the numerical analysis tool for a multiple-fan ventilation network, information regarding the related laboratory tests is very scarce. To make up this gap, laboratory experiments have been done by using a two-fan experimental network. This paper presents the methodology and major findings regarding the construction and features of a subsystem characteristic curve. Characteristic curves and measurement fundamentals A characteristic curve A characteristic curve is a graphic presentation of the relationship between any two variables of a two-terminal component. It is typically defined in the form of a quantity-pressure curve for a ventilation component, which can be a single branch (airway), a fan, a regulator, a portion of a network or even a whole network. If a component is a single branch, the curve is called a branch characteristic curve. If it is a fan, then the curve is called a fan characteristic curve, and so on. Figure I illustrates the characteristic curves of some typical ventilation components. A general method for obtaining a characteristic curve from measurement is to apply an adjustable-pressure source between the two terminals of a component and measure the quantities corresponding to the different pressures. Mine characteristic curve A single-fan network can be easily divided into two ventilation components, the fan and the remaining network. The latter consists of only branches and regulators. Under this subdivision scheme, two characteristic curves can be constructed. They are the fan characteristic curve and the characteristic curve of the remaining network. The latter is referred to as the mine characteristic curve or the system characteristic curve. Although the general method for constructing a characteristic curve from measurement can be applied to obtain a mine characteristic curve, there is a shortcut for constructing the curve by introducing a mine resistance factor R. It is a constant if all of the resistance factors in the network are constant. R relates mine pressure H with quantity Q as in: H=RQ2 (1) For a given R, Eq. (1) can be directly used to plot a mine characteristic curve by assigning a series of Q values and calculating the corresponding H values. Hence a shortcut to constructing a mine characteristic curve is to measure one set of mine pressure H and quantity Q values, calculate the mine resistance factor R using Eq. (1) and then plot the curve. Subsystem characteristic curve Applying a similar scheme as is used for a single-fan system, divide a multiple-fan network into two components, a fan under consideration and the remaining network that contains all the other elements (branches, regulators and remaining fans) of the network. The fan under consideration

Jan 1, 1994

By John Corcoran

INTRODUCTION Content of this Report The 1300m long twin-bore 8.1m diameter Airside Road Tunnels (ART) were excavated beneath the busy taxiways and stands of Heathrow Airport between 2002and 2003. The tunnels were fully completed and handed over to the client for use early in 2005. This paper will describe the purpose of the tunnels, and the measures put in place to minimize the impact of construction on the daily activities involved in running an international airport. Terminal 5 Construction Heathrow Airport is the busiest international airport in the World, with a current capacity of circa 67 million passengers per year, based on existing infrastructure of4 passenger terminals, 1 cargo terminal, 2 runways and 170 aircraft stands. Terminal 5(T5) is being built to increase Heathrow’s passenger capacity by providing the following: 12 additional aircraft stands through redevelopment of the south apron area, in the autumn of 2004 A main terminal building (T5A) and a first satellite (T5B), and 43 additional stands by the spring of 2008, most of which will be able to receive the new generation large aircraft (Airbus A380) A second optional satellite (T5C) by year 2010 A third optional satellite (T5D) by year 2015 The total value of the project is approximately 4.2 billion pounds for the main phase of the works spanning from 2000 to 2007. Purpose of the Airside Road Tunnel The ART has been constructed to support the internal road traffic of the airport between terminals, aircraft stands, runways and taxiways, for passenger buses, service and technical vehicles. The majority of the traffic will be buses transporting passengers between the terminals and their aircraft.

Jan 1, 2005