Search Documents

By A. Chieregati

"A heterogeneity study was conducted at Erdenet Copper Mine in Erdenet, Mongolia, to determine the fundamental sampling error associated with blasthole sampling. Using a custom designed sector sampler, six large blasthole samples were collected to perform the test that was developed by Pierre Gy, to estimate the constitutional heterogeneity factor for several types of ore. The study investigated the entire sampling protocol, from mine site to analytical laboratory, and quantified the contributions to fundamental sampling error (FSE) of the various stages of sampling and sample preparation. The total relative standard deviation (RSD) of sampling error was determined to be ±32% and ±49.4% for copper and molybdenum respectively. A classical statistics analysis conducted on the data confirmed the level of RSD. About 95% of the sampling error was produced from only one step in the sampling protocol: when the 1 kg sample was reduced to 50 g sample for chemical analysis. Therefore, it is recommended that the 1 kg sample be reduced to 50g using a slightly different protocol to minimize the FSE. The 1 kg sample should be first crushed to 0.2cm size. A 250g split should then be taken and fine ground. A 50g split should then be taken from the 250g fine ground split. These two simple steps will reduce the FSE to ±7.9% and ±17% for copper and molybdenum respectively. The modified sampling protocol effectively reduces the probability of misclassification of low grade ore to zero. INTRODUCTION The Erdenet copper-molybdenum open pit mine is located in Erdenet, in Orkhon province, Mongolia. The Erdenetiin-Ovoo copper-molybdenum deposit is between 1.5 and 3 km wide, and about 25 km in length (Erdenet Mining Corporation, 2016). Chalcopyrite, bornite covellite and chalcocite are among the major minerals found in the deposit. The mine processes approximately 26 million tons of ore annually. A study was conducted to evaluate the fundamental error associated with the blasthole cuttings and sampling protocol at the mine. The open pit mine uses 215mm diameter Russian drills to drill 17.5m holes for 15m benches. The total weight of blasthole cuttings for a 215mm diameter hole and 15m bench height is between 1.5 and 2 tonnes. This amount of sample is difficult and time consuming to collect and analyze. Therefore, a sector sampler was designed for the Russian drills to collect large samples that were representative of the blasthole cuttings (Ganguli et al., 2016). In order to eliminate the delimitation and the extraction errors, researchers consider sector samplers to be ideal for sampling blastholes (Pitard, 2008; Chieregati and Pitard, 2009). This method was intentionally more rigorous than the blasthole sampling protocol at the mine to ensure that the blasthole cuttings were properly sampled. This study was part of a broader study that also looked at the relationship between particle size and grade. The samples collected by the custom designed sector sampler were very large (195 kg on average), and therefore, sufficient for both studies. The relationship between particle size and grade has been reported in Ganguli et al. (2016)."

Jan 1, 2017

By E. J. Haas, K. A. Rost

"This study sought to identify changes in continuous mining machine (CMM) operators’ risk perception and risk behaviors as a result of adding a proximity detection system (PDS) into their environment. To accomplish this research task, 9 CMM operators from 5 locations were interviewed. Interviews were thematically analyzed for constructs including patterns in risk perception and behavior before and after PDS integration and the process of adapting to the PDS. Operators discussed standing in the red zone less than they did before using the PDS; however, they also discussed other risky decisions they made while learning how to operate their CMM with the PDS technology such as “cheating” the technology and working faster to meet production goals. The process of relearning job tasks with technology and unintended behaviors as a result of that relearning process need to be taken into account when introducing new technology into the mine environment. The study results show an in-depth view of mine workers’ perspectives and how their job tasks and environment could be or are affected when learning how to use new technology that are relevant to companies and mine operators when introducing new technology into the mine environment. INTRODUCTION Established “red zones” can help prevent striking and pinning incidents by providing guidance to continuous mining machine (CMM) operators about where they should stand and not stand while operating a CMM. Although red zones influence operator placement positions, these guidelines are not foolproof safety mechanisms. Depending on the job task and circumstances of the mine environment, a CMM operator may unintentionally or intentionally stand in a red zone. For example, CMM operators may work in close proximity to their CMM for better visual attention cues and the ability to work at a higher rate of production [1-3]. To further enhance protection and prevent collisions between vehicles and mine workers, a proximity detection system (PDS) was developed for the industry. The PDS determines an individual’s position relative to a specific piece of machinery, issues visual and/or audible warnings to the mine worker to change positions, and, if necessary, disables machine motion [4]. The introduction of new technology within other sectors has been identified as a factor that influences work decisions. Specifically, previous research demonstrates that when technology debuts there can be an initial intrinsic risk perceived among users about how the technology will interact with their current environment and behaviors; however, these ambiguities, including the possible risks and benefits, are seldom studied [5]. Some research suggests that the constant presence of technology can disrupt situation awareness and decision-making capabilities by increasing worker responsibilities and worker cognitive demands [6-8]. Further, if workers’ perceived risks both with and without technology are misjudged, unsafe decisions that result in human error and injury may be more likely [9-11]. Although these statements are provided within a broad contextual framework, they support the need to study how technology is perceived among end users in their own environment. Because research about technological impact on worker behaviors has suggested both positive and negative consequences of technology, this issue is worth addressing in the mining industry. Specifically, research has not determined whether CMM operators view their placement choices in the red zone as safe or risky and what effect PDS technology has, if any, on risk perception and subsequent risk behavior."

Jan 1, 2015

By Neel Gupta, Dustin M. Crandall, Brijes Mishra

X-ray computed tomography (CT) images of rock specimens often contain artifacts which must be corrected before scientific analyses are performed. This paper presents a new workflow of automated image processing to utilize poor-quality X-ray CT scan images. The workflow runs on the open-source image analysis software and efficiently separates desired features from low-contrast scanned images. The new workflow is a two-step technique using contrast enhancement and automated feature segmentation to generate noise-free binary images. The results of binary images using the proposed workflow and using a conventional thresholding technique are analyzed to show the quality of the proposed method. The paper also presents a workflow of estimating the structural geometries of features in two and three dimensions. The results of the structural feature analyses and computational time were compared between the open-source (ImageJ) and commercial image analysis software (Bruker Computed Tomography Analyzer). The commercial software was more computationally efficient, but the task-specific macros in open-source software enabled the user-desired automation in image processing and data extraction of desired structural features of comparable quality.

Sep 8, 2022

The Cutoff grade optimization is very critical to the open pit production scheduling. In case of single mineral deposits, algorithms have been developed for determining cutoff grade policy that maximizes the net present value (NPV) of yearly cash flows. For deter-mining the cutoff grade policy for projects with two minerals including stockpiles the problem becomes much more complex. The purpose of this paper is to present fundamentals of a generalized cutoff grade optimization algorithm that will maximize the NPV of a project subject to mining, milling, and marketing constraints. Benefits of the methodology developed are demonstrated on three different case studies.

Jan 1, 1997

By C. J. Kirkland

The paper describes the arrangements for the casting, curing and handling at the casting yard, of the concrete segments for the lining of the UK half of the tunnel, and the plant used for the handling of these linings at the construction site. An outline of the tunnel boring machines being used is given, with particular reference to lining handling and erection, and the extensive muck disposal systems installed. A general progress update will be given to the conference.

Jan 1, 1989

By D. D. Schlepp

There is a continuing debate about the influence of circulating load and classifier efficiency on the capacity of the circuit. Specifically, the effects of preferential classification, bypassed fines, and the sharpness of classification will be examined. Horizontal cyclones have also proven to be very successful in a number of operations but their impact on the circuit capacity has not been clearly defined.

Jan 1, 1990

By S. R. Brown

A number of relatively recent factors associated with the design of new metallurgical processing plants have made the effective training of operators a requirement for a successful start-up. Some of these factors include large capital investment in a minimum of processing lines, highly complex process control systems, and stringent regulations on plant effluent, to name a few. More than ever, operating mistakes during the start-up phase can lead to substantial delays in achieving design production, as well as problems with government authorities if permit limits are exceeded. The only way to assure your return on plant investment is to ensure new plant operators have the knowledge to properly run the plant from the outset. A comprehensive set of operating manuals specifically targeted for plant operators and foreman, written by experienced operating personnel, is the only effective way to provide the necessary information for start-up-related training.

Jan 1, 1995

By James N. Brentz

This paper deals briefly with the problem of efficiently selecting the most cost effective haulage truck. Problems and factors are identified that effect productivity and operating cost. Despite the sophistication of computerized vehicle simulation programs, there is a wide disparity in accuracy and methodology, particularly in dealing with the various elements of cost.

Jan 1, 1984

By J. P. Gliddon, G. C. Wade, J. W. Lill

Since 1980 a number of significant changes have been introduced at Palabora in an effort to offset the effects of reduced product price and increased unit costs of production. These changes and improvements include major equipment rationalization programs, the introduction of trolley-assisted truck haulage, adoption of a sophisticated computerized truck control system, pit design enhancements, improved drilling practices, use of emulsion explosives, and the installation of an in-pit crushing and conveying system. The various changes, their effect on the operation, and their contribution to cost reduction and improved productivity at Paihbora are considered.

Jan 1, 1987

By W. G. Pariseau

"BACKGROUND Strata mechanics of three underground coal mines in central Utah were recently studied using a specialized finite element technique [1, 2, 3, 4]. The purpose of these studies was to examine relationships between mining and related seismicity. The longwall mining method was predominant, but room and pillar mining and barrier pillar mining were also used in the mines studied. In every case, high correlation between face advance and seismicity was observed. The specialized finite element technique allows for whole mine subsidence estimation at a kilometer scale and for stress concentration at a meter scale near a working face. Comparisons of observed mine subsidence with model subsidence allows for model verification and justifies detailed analysis of the evolution of stress at seam level. Yielding is expected near a longwall panel face and as the face is advanced the extent of yielding is expected to increase. The total number of element failures in a finite element mine model also increases, so a high correlation with associated seismicity, say, event count, is not so surprising. A brief review of recent coal mine studies in Utah is presented in the sequel. The procedures are given in some detail in application to trona mining. COAL MINES The analysis procedure begins with the geologic column and proceeds to specification of strata properties including elastic moduli and strengths. Joints are an integral part of the geologic model and joint set specifications include dip direction, dip, spacing, stiffness and strength. Spatial variability of strata properties in situ may be taken into account during analysis. Topography is important, especially to Utah coal mines that are developed from outcrop in regions of high relief. Mesh generation follows specification of data input. Finite element analysis is next, followed by reporting of results. In this regard, all finite element computations are based on first principles. No model “calibration” is done that involves adjusting computer input to obtain a fit to mine measurements such as subsidence profiles. Figure 1 illustrates the concept of a dual node – dual mesh finite element concept. Dual nodes are roof and floor nodes in mined areas. These nodes replace the seam. The dual mesh is a much refined mesh with displacement boundary conditions obtained from the big mesh and thus replaces the effect of mining in the region outside the dual mesh. The refined dual mesh allows for details of stress, strain and displacement near a working face of interest. Strata Properties Strata properties include elastic moduli and strengths of intact rock between joints and joint stiffness and strength for each joint set present. Both properties sets may be obtained from laboratory test data, although testing joints poses a sampling problem in the field. The statistical variability observed in laboratory test data, say, in unconfined compressive strength tests is often characterized by much variation. In fact, the coefficient of variation, ratio of standard deviation to mean, is often greater than 35 percent. When sample values are mapped back to the mine location, one may observe spatial variability as properties vary from place to place as shown in Figure 2. Spatial variability may be incorporated into a finite element analysis with probabilistic assignment of properties to elements in accordance with measured variability. The result is a more realistic model of rock in situ."

Jan 1, 2017

By Sahendra Ram, Ashok Kumar, Rakesh Kumar, AMIT KUMAR SINGH, Dheeraj Kumar, Arun Kumar Singh, Rajendra Singh

This article offers an examination of a retreat mining method conducted at the Pinoura Mine in India from 2010 to 2017. The method is atypical for coal mines of India’s coalfields. The method executes depillaring in a single pass and does not require the formation of galleries and support installation in splits, thus, reducing the cycle time. A variety of observations are discussed throughout this work and emphasis is placed on field measurements and depillaring under weak roof (RMR = 40–45). This paper discusses design techniques, specifically the estimation of the snook (remnant pillar) size, and important practical observations after the fact. The execution of this method was eventually conducted in eleven panels.

Aug 4, 2020

By Pratt Rogers, Aaron Young

This paper considers the mining industry’s need for digital transformation (DT) and presents a three-part review of the foundational components of the DT process: ubiquitous data, connectivity and decision-making. It also provides a discussion on the future of DT in mining as well as a research direction, which identifies the need of academia to provide support for mining companies in the form of both research and the education of digitally literate, dynamically capable mining engineers into the coming decades.

By E. Siami-Irdemoosa, S. R. Dindarloo

Ease of excavation or rippability, also called diggability or excavatibility, is a critical decision-making parameter in the selection of both the overburden removal method and the required equipment in surface mining and geotechnical engineering projects. The most widely used method of estimating rippability is rock mass classification. Although there are different classification schemes in the literature, all of them have the two major limitations of sharp transitions at class boundaries and subjective uncertainties in decision making. In this study, the decision trees method was employed as a classification tool for estimating ground rippability, using the four rock mass parameters of weathering degree, uniaxial compressive strength, joint spacing and bedding spacing. The results were compared with those of the widely used method of diggability index rating (DIR) and a fuzzy-based DIR. The problem of subjective uncertainty was resolved in the proposed decision trees method, as the tree rules were derived automatically from the training data sets. Compared with fuzzy-DIR, a decision tree classifier is simpler, needs less computational time and is more appreciable by industry practitioners. Nevertheless, the proposed method is not flawless and, similar to both the conventional and fuzzy DIR methods, yielded poor estimations in particular instances. The limitations of the three methods are discussed.

Jan 1, 2015

By K. P. Wang, Ta M. Li

The Chinese energy and mineral industries are readying themselves for a period of dynamic transition, unprecedented in the country's long and sometimes turbulent history. The transition comes as a result of the government's new program of "Four Modernizations" in its agricultural, defense, industry, and science and technology sectors. The announced program is generally considered by Western observers to be a moderate, pragmatic approach to get China on the road to industrial parity with Western nations by the year 2000. The game plan calls for integration with the West to beef up Chinese know-how and the purchase of foreign technology to supplement areas where China lacks the ability to do so itself. While the role of energy and minerals is not specifically mentioned in the program, it was made clear to ME that China realizes the basis of any sustained modernization program is tied closely to the health of its minerals sector. Various published reports have indicated the existence of an already vibrant energy and minerals sector with world rank production in coal, iron ore, tin, antimony, cement, pyrite, asbestos and tungsten to name just a few. For the most part, except for the export metals, the primary focus of China's production has been on fulfilling domestic needs. Now the new initiatives are aimed not only at self-sufficiency, but also on propelling the country's natural resource clout into international prominence. With a mineral resource base that is considered by many westerners a potential bonanza, China's new long march toward modernization will be an exciting adventure, well worth watching. Big Projects Spark Excitement China's renewed commitment to a more liberal program is as much a desire to "walk on its own two legs" as it is a backlash from the frustrating years that followed the Cultural Revolution of the 1960s and early 1970s. Much of the early excitement was initiated by China's Premier and Party Chairman Hua Guo-feng in speaking to the fifth National People's Congress (NPC) in 1978. Here, Chairman Hua presented the Communist Party's 10-year blueprint for economic development. Specifically, the Party's plans called for completion of 120 large-scale industrial projects by 1985. Mentioned were 10 new iron and steel works, 30 power plants, six new railways, 10 oil and gas fields, nine nonferrous metal

Jan 3, 1980

By Osvaldo A. Bascur

Standards and technology for bringing information to the desktop have greatly evolved in recent years. The benefits to be realized depend on how these new tools are embraced at the performer level. A key operating challenge is to ensure cooperative effort is geared towards the most efficient achievement of identified operating and corporate objectives. Presentation, application and database layers are emerging in successful client/server applications, the three-tier architecture.

Jan 1, 1996

By B. K. Cantrell

A miner working in an underground coal mine with diesel equipment is exposed to a wide array of pollutants from the diesel exhaust. These include CO, CO2, NO, NO2, SO2, diesel-exhaust aerosol, and a variety of hydrocarbon compounds. A quantitative definition of the health risk resulting from these exposures remains elusive, but during the past several years, progress has been made in defining the problem. Results from epidemiological studies by Garshick, et al. (1988); animal inhalation studies by Mauderly, et al. (1986); Iwai, et al. (1986); and Brightwell, et al. (1986); and in vitro studies by Lewtas, et al. (1986), have provided sufficient data for the National Institute of Occupational Safety and Health (NIOSH) to recommend that "whole diesel exhaust be regarded as a 'potential occupational carcinogen,' as defined in the Cancer Policy of the Occupational Safety and Health Administration," NIOSH (1988). NIOSH further stated that "though the excess risk of cancer in diesel-exhaust-exposed workers has not been quantitatively estimated, it is logical to assume that reduction in exposure to diesel exhaust in the workplace would reduce the excess risk."

Jan 1, 1990

By Joseph D. Drew

Oregon Resources Corp. (ORC) has developed and permitted a new mining operation that incorporates a process design that will allow the unique paleo-beach placer deposits of southwestern Oregon to be extracted efficiently and economically, creating the only domestically mined source of a unique foundry grade chromite and specialty de-veining sand for precision casting. The operation will also provide an additional domestic source of garnet and zircon. Engineering design has been guided by the variable geology and mineralogy of the paleo-beach placer deposits as well as the need for a dry tailing scheme that resolves a lack of water resources at the placer locations and at the same time eliminates the need for slurry settling ponds, typical of paleo-beach placer operations in North America.

Jan 1, 2010

By J. C. Stankus

Many coal seams are associated with soft floor strata and during mine development if coal pillars are not properly designed, floor heave occurs and causes interruption of coal production. In the severe cases, the section or mine is abandoned. One of the methods for controlling floor heave is floor bolting. This paper describes the demonstration of floor bolting methods in a West Virginia coal mine. Three methods were used: (1) vertical full resin bolting, (2) floor truss bolting, and (3) floor truss bolting plus a floor cut at the center of the entry. The design of each method and the experimental results are discussed in detail.

Jan 1, 1993

How do you think the US Bureau of Mines closing will affect SME? The demise of the bureau represents a challenge, an opportunity and, above all, new responsibilities for our profession. A lot of good professionals are seeking new positions. A lot of worthwhile research is available for transfer to the private sector. Logic dictates that worthwhile projects of any defunded government activities should find support in the private sector. The bureau may be gone but its legacy is deeply rooted in the profession. The bureau’s contributions will be remembered as long as there are mines and miners. Its1994 research program was divided into three major areas: environ-mental technology; health, safety and mining technology; and minerals and materials science. There must be a place in either the government or private sector to continue these worthwhile activities.

Jan 1, 1996

By Sean Cassady, Jason Liu, Sanja Zlatanic, Taehyun Moon, Chris Devery

"For the Hollywood International Airport Runway Expansion Project at Fort Lauderdale, Florida, the structural fire durability analysis was completed for a series of tunnels formed by roadway and railroad cells located under the runway structure. A systematic design approach was developed to mitigate structural damage during a fire event and arrive at a practical method to structural fire engineering that is compliant to NFPA 502. To ensure the NFPA 502 requirements are satisfied, the performance based approach was implemented and the engineering analyses were performed for the adopted design fire event. The analyses considered the facility’s unique features including its fire safety systems to determine applicable design fire curves for structural durability analyses. The paper also outlines the process of defining the project specific fire curves for a specific design fire scenario and summarizes the results of heat transfer and structural fire durability analyses. This approach was aimed to assist the owner and Authority Having Jurisdiction to achieve practical decisions to the tunnel facility fireproofing.INTRODUCTIONFort Lauderdale–Hollywood International Airport (FLL) in Broward County, Florida is a major hub facility serving more than 23 million passengers annually. As part of the Airport Expansion Program, the South Runway (9R-27L) Expansion project aimed to meet ever increasing service demands via an increase to runway lengths. This necessitated the placement of one of the reconstructed runways on bridge structures over the existing U.S. Route 1 (US 1), a major north–south U.S. Highway that serves the East Coast of the United States, and the Florida East Coast (FEC) Railway, thus effectively creating multiple tunnel cells beneath the subject runway. For this project, HNTB suggested a tunnel fire damage mitigation system that would protect the runway major structural elements from the design fire event that may happen within the tunnel cells. This paper addresses the issues related to the fire event originating within the tunnel encompassing the US1 highway only, and deals with requirements of NFPA 502 [5] exclusively. Therefore, while approaching the structural fire protection issues for the specific tunnel cells beneath the runway structure, the requirements of the American National Standard NFPA 502 (Standard for Road Tunnels, Bridges, and Other Limited Access Highways, 2008 edition) were followed. Per this standard, regardless of tunnel length, all primary structural concrete and steel elements shall be protected in order to:"

Jan 1, 2016