Search Documents

By A. K. Mukherjee

The roles of pulsating mechanisms such as the amplitude and frequency of the jig cycle are well established in jigging. Also well established are the roles of the size ratio and the volume fraction of the feed. In iron ore beneficiation plants, these process parameters are optimized to achieve the highest efficiency. However, the role of one of the more important feed characteristics, the liberation characteristic of the feed, has not been studied in detail. Evaluation of the liberation characteristics is difficult because the required washability test is not viable for iron ore feed. In this paper, a new method is proposed in which the liberation characteristics are measured through a separation efficiency value. In the new evaluation method, jigging parameters such as amplitude and frequency of the jig cycle are optimized from the fundamental understanding of the process dynamics and feed characteristics such as size distribution. Then, feeds with different liberation characteristics are tested to evaluate the liberation characteristics of feed in jigging.

Jan 1, 2008

By Edgardo Fogli, Mario Lampiano, Antonio Nicola

The project is located in the northern region of the People’s Republic of China and was awarded to Impregilo, as sponsor of the Wan Long Joint Venture, in September1997. The project consists of four tunnels for a total length of 88,700 m, with an excavation diameter of about 4.9 m. The lining is made of honeycomb pre-cast segments, connected by PVC dowels and the joints are sealed with elastomeric gaskets. The geology is mainly Limestone, Dolomite and Sandstone. Karst cavities are abundant and are often in-filled with plastic red clay. This has adversely affected the TBM’s progress. Four double shield telescopic TBMs were mobilized to cope with the very tight construction schedule and, at the end of November 2000, more than 80% of the tunnel has been bored. The article analyses the TBMs’ productions in the various geological conditions and the results of different technical solutions adopted at the project.

Jan 1, 2001

By A. Korchevskiy

While Russia continues to be a worldwide leader in asbestos production, the environmental and health status around Russian asbestos mines is not well known and understood, internationally. A literature review was performed to evaluate the potential impact of Russian mining operations on mesothelioma incidence rates in the Ural region where the majority of the asbestos deposits are located. Asbestos that has been mined in this region includes chrysotile, crocidolite, and anthophyllite forms. The Nicholson-Peto (1986) model was applied to published exposure data and mesothelioma mortality statistics in different cities and villages of the Ural region to estimate mesothelioma potency factors (KM) for the various associated fiber types. It was demonstrated that mesothelioma potency factors, as determined by Berman and Crump (2008), could be used to predict mesothelioma risks of non-occupationally exposed individuals in locations where either pure chrysotile, or both crocidolite and chrysotile, are mined and milled. A mesothelioma potency factor was calculated for anthophyllite that appeared to be higher than expected based on previously published studies. The highest incidence of mesothelioma was identified in a community close to a crocidolite mine. The study confirms the validity of utilizing current risk models for non-occupationally exposed populations near asbestos mining activities where asbestos exposures are relatively low and provides methods of characterizing mesothelioma risk in the former Soviet republics (FSRs).

Feb 27, 2013

By Richard E. Gertsch

Mechanical mining holds great promise for the mining industry. Realizing this promise depends on developing the tools needed to mechanize a mining operation with a reasonable expectation of success. Mechanical mining entered the 1990s with new machines, new operating methods and new ideas for the future. Mechanical mining can provide higher production, increase safety, reduce roof support requirements, create smoother openings for better ventilation, substitute continuous production for cyclical drill-and-blast procedures, and create opportunities for automatic and teleoperated control. The full promise of this important technology still lies ahead. Obstacles include: • Long-term production prediction: Mechanical systems have a high capital cost. Although recouped by lower operating costs, the tradeoffs are not always clear to mine operators. • Cutting tools for hard rock: Rock of more than 103.4 MPa (15,000 psi) cannot be cut by flexible mining machines. • Machine designs: Many machines cannot convert the required power into rock cutting capability. • Engineering: Better use of the machines in the mine is needed.

Jan 1, 1994

By J. Torma-Krajewski, C. Hipes

Many mining companies apply ergonomic principles, but it is done either informally and/or reactively. Examples of an informal approach include replacing worn equipment, such as seats, with models that have ergonomic features, or modifying tasks to eliminate safety hazards that will also reduce risk factor exposures that may result in musculoskeletal disorders (MSDs). A reactive approach is followed when modifying a task/equipment after an MSD occurs. Neither one of these approaches involves a systematic method of proactively applying ergonomic principles to actually prevent injuries or illnesses. This paper will discuss how Vulcan Materials Company applied ergonomic principles and the interventions implemented to reduce risk factor exposures.

Jan 1, 2007

By M. Maier

Geographic Information Systems (GIS) has evolved into a powerful tool for analyzing spatial and attribute data in many industries including mining. Modern field data collection techniques add another dimension to the use of data in the field and enhance the utilization of GIS for mining applications. This discussion will review how field data is collected and how office data and maps can be taken into the field to be analyzed and verified using pen-based computers and differentially corrected GPS.

Jan 1, 2001

The more than 40,000 mining industry professionals that are expected to attend the National Mining Association’s(NMA) MINExpo International2000 trade show and conference will be treated to the exhibition’s largest display ever. The exhibit is expected to cover more than 60,385 m2(650,000 sq ft) and feature more than 1,300 exhibitors. The event is set for Oct. 9-12, 2000 at the Las Vegas Convention Center in Las Vegas, NV. Richard L. Lawson, NMA’s president and chief executive officer, said, “MINExpo 2000 will showcase everything that mining is proudest of. This is the largest premier mining exposition in the world.” MINExpo is held every four years.

Jan 1, 2000

By C. Arthur Lefler

The hydrometallurgical processes for recovery of gold and silver in use at Round Mountain, Nevada and the practical aspects of the operation are discussed. Included are heap leaching by cyanidation, upgrading of solutions by adsorption of values on activated carbon and desorption (stripping) for electrowinning and subsequent refining steps to produce dore metal.

Jan 1, 1981

By A. Habibi

The ventilation survey was conducted in an underground longwall trona mine. The mine is relatively shallow and categorized as a gassy mine. The ventilation system consists of nine shafts (three intakes and six exhausts). Three surface based axial fans ventilate the mine configured in a blowing arrangement. Following the ventilation survey airflow quantity, frictional pressure losses and air psychrometric characteristics have been quantified. An accurate resistance survey has been conducted to calculate the pressure drop with regard to moving cages and skips in the shafts. This paper discusses the benefits of utilizing high accuracy digital pressure transducers and psychrometers in a ?leapfrogging? survey to gather data needed to build the computer ventilation model. Two underground booster fans with VFD are currently idle but available at the mine. The ventilation model has been used to determine the optimal booster fan locations to decrease the overall operating cost by reducing the load carried by the main fans. A leakage study has been conducted to evaluate the effects on the system of additional pressure from a booster fan. The study finally prepares a future ventilation model for the next fifteen years of mine operation and investigates the effect of proposed scenarios.

Feb 27, 2013

By Larry F. Drolet

Charleston, SC is anything but boring. The city was founded in 1670 and has played a significant role throughout the history of the United States. Located along the coast of the Atlantic Ocean in the southeastern United States, Charleston was a vital city in America?s early existence. Charleston?s coastal location has helped the city become the fourth largest cargo port in the United States and earn the 2011 designation as the number one travel destination in the United States by the Conde Nast Traveler Magazine. Part of Charleston?s charm and beauty can be attributed to its historic structures and churches that line nearly every sidewalk, roadways that were laid out based on the width of horse carriages, great weather, southern hospitality and coastal living. Now imagine the challenges of installing new, or re-placing aging infrastructure, in this setting. Every shovel full of dirt, every stick of pipe and every roadway sub-surface has its own historic story to tell. For engineering minded individuals, Charleston?s infrastructure has almost as fascinating a history as its more visible surface structures. Charleston was among one of the first American cities to construct separate sanitary and storm water drainage infrastructure. This concept has roots dating back to the city?s founding and is a credit to the foresight of its founding fathers who understood the basic health differences between sanitary and storm water.

Jan 1, 2013

By Steven W. Hunt, Isabelle Lamb, Steven B. Fradkin

Groundwater control is generally an important consideration and significant source of risk during most tunneling projects. Proper baselining of groundwater conditions requires: 1) a thorough understanding of the geological environment; 2) a focused site investigation; 3) identification of construction and adjacent property damage risks associated with inflows and short and long term piezometric level changes; and 4) consideration of contractual issues including restrictions on means and methods and pay items for associated work. This paper provides an overview of groundwater baselining issues and risks based on selected design studies and construction case histories.

Jan 1, 2005

By Yifan Ding, Shemek Oginski, Patrick Finn

The Manhattan section of the New York Water Tunnel No. 3 constructed by the Schiavone/Shea/Frontier-Kemper Joint Venture is a $668 million project. The contract includes a tunnel drive of 8.85 km (29,045 feet), tunnel lining of 14.77 km (48,468 feet)and construction of nine shafts ranging in depth from 143 m (469 feet) to 169 m(555 feet). Construction methods for excavation of the shafts are presented including raise bore, ground freezing, soil excavation, blasting, slashing, muck handling, rock support and shaft final concrete lining.

Jan 1, 2007

By J. Hansen

This paper has been written for presentation during the Open Pit Mining Session at the SME Annual Meeting and Exhibit, Denver, Colorado, February 26 to 28, 2001. The paper addresses the application of automated monitoring of electric rope shovels to improve performance and blasting technique.

Jan 1, 2001

By Marianne Snedeker

In September 1985 we published a questionnaire asking about the content of MINING ENGINEERING and about your interests. By Dec. 10, our cutoff date, we had 430 responses, representing about 1.5% of the 28,238 people who received the September issue of ME. In the data that follow the tabulation and percentages are based on the number of individuals who responded to the particular question. About ME Through responses to the questionnaire, we were hoping to learn more about you, your interests, and how the magazine could better serve you. Those of you who responded told us something positive - you look at or read the magazine. Of the 430 respondents, 428 or 99.5% indicated that they had read or looked through the July and/or August issues. Those of you who refer to the magazine once are 207 or 48.5%. Those of you who refer to the magazine two or three times are 193 or 45.2%. Those of you who refer to the magazine four or more times are 27 or 6.3%. How much time do you spend reading the magazine? Of those responding to this question: 64 spent up to 1/2 hr 15.0% 224 spent up to 1 hr 52.6% 115 spent up to 1-2 hr 27.0% 23 spent more than 2 hr 5.4% In an informal survey among our staff, we determined that most people spend 1/2 to 1 hr reading magazines to which they subscribe at home. Does that match your experience? Many of you, 335 or 79%, clip your magazine for further reference. Also, many of you, 313 or 73.6%, do not pass your copy on to another reader, indicating that you are clipping it or receiving the magazine at home. Those magazines that are passed on reach: 1 person 3 0.7% 2 people 64 15.1% 3-5 people 34 8.0% 5 or more 11 2.6% Answers to what portions of the magazine you find useful indicated that the top three were Industry Newswatch, feature articles and Technical Papers; see Table 1. The "other" category included advertising - display, classified, Employment, and Professional Services - Washington Survey, New Products, Free Literature, book reviews, technology news, and Coming Events and Short Courses. We asked your appraisal of the technical level of the magazine. Of those responding, 39 or 9.1% indicated that it is too technical, 55 or 12.8% indicated it is not technical enough, and 335 or 78.1% judged it to have the correct technical level. In response to the question about whether you like to read an occasional feature that is not technically oriented, 21 or 5.1% said no, but an overwhelming 94.9% (393) said yes. Of the specific

Jan 1, 1986

With the dawning of a new century came the beginning of a new era in the coal industry. Instead of the traditional practice of only buying and selling produced coal in the United States, a coal futures market was established. The New York Mercantile Exchange began trading coal futures in July 2001. But, even in this new era, many of the old is-sues that have beset the coal industry still remain, as was evident in2001. Coal production increased to are cord level during 2001, according to preliminary data from the US Energy Information Administration(EIA). Production in 2001 rose by4% to 1.01 Gt (1.12 billion st), compared with 2000 (Table 1). This barely surpassed the previous record level of 1 Gt (1.11 billion st)set in 1998. Coal consumption remained unchanged. The additional production was used to replenish the depleted stockpiles that had resulted after two years of declining coal production and increasing coal consumption.

Jan 1, 2002

By Donald E. Raab, Lee W. Saperstein

INTRODUCTION The Premise Not much time has to be spent in a tunneling project to realize the tremendous interdependence that exists among the various unit operations. The research that is to be described attempts to examine one set of these linked operations, namely, the effect of cutters on muck handling properties. All too often research focuses on too minute an aspect of a problem for the results to be of much immediate, practical use. The goal of this research is to avoid this specificity. Apologies are tendered if this goal is missed. It is known that the mode of flow of bulk solids under the influence of gravity -- emptying a bin or hopper -- is dependent on several basic parameters. The size of the particles and the distribution of sizes (consist) determine whether the solids will first flow out of a given aperture; the cohesion of the solids will determine if flow will continue after the bin is opened; and the angle of internal friction determines the size of the flow regime (1,2,3). It is well understood that the latter two parameters affect the behavior of bulk material on a conveyor belt. Cohesion of material to a belt is always an undesired problem. Heaping of material on a belt depends on the material's internal friction. It is also known that varying the particle size, and the packing density of the material can affect the material's angle of internal friction (4,5). The question was posed whether sufficient variation in a mechanical tunneling machine's (mole) cutting function could be arranged to affect materially the handling properties of the muck

Jan 1, 1974

By James Diekmann

The Disputes Potential Index (DPI) is a computer program designed to help team mem¬bers assess the likelihood of contract disputes on a construction project. The program's predictions are based on data from 159 construction projects that encompass a variety of public and private projects. The impact of three categories of project characteristics are included in the DPI program, specifically, people, process and project characteristics. Ultimately, DPI returns an overall project score that indicates the likelihood of exces¬sive contract disputes. The output of a DPI analysis can be used as part of a contract readiness review or to define the need for extraordinary dispute avoidance procedures. This paper examines the development of DPI and presents the results of DPI analyses on several tunneling projects.

Jan 1, 1995

By M. S. Klima, P. T. Luckie

Proper analysis of washabiity data can lead to the development of a maximum yield coal preparation plant flow sheet. Simulations, as simple as spreadsheet mass and water balancing, are important in examining yield maximization and middlings liberation. Key to such attribute tracking flow sheet simulations is the distribution model, expressing the probability of a species reporting to the product stream. There are many such models in the literature. This paper examines a functional form that can represent or fit most of the proposed distribution functions.

Feb 24, 1997

The Functional Performance Equation for ball milling circuits allows us to isolate the circuit classification system efficiency (CSE) from the mill?s grinding performance. The factors which affect circuit CSE are reviewed, with emphasis on water usage at the classifiers. It is shown that manipulation of such water usage can be carried out to improve plant grinding circuit efficiency, at times by more than 30 percent.

Jan 1, 2009

By Lewis V. Wade

This paper summarizes the results of the rock mechanics monitoring program performed as part of Old Ben Coal Company's longwall coal mining demonstration project conducted in cooperation with the United States Bureau of Mines. The work described herein included installation of instruments, collection of data and data analysis performed during mining of the first longwall panel in Mine No. 24. The rock mechanics monitoring program included both surface and underground instrumentation and was designed to achieve the following purposes: 1 -To provide the capability to observe unusual situations during mining so that remedial measures could be instituted quickly 2 -To formulate design guidelines for future longwall mining efforts; 3 -To evaluate surface subsidence, and its character, rate and potential effects on cultural features, and to develop criteria to assist in predicting subsidence for other mines having similar roof conditions. Six previous attempts with longwall methods in Old Ben Coal Company's Hine 21 had been unsuccessful due to roof control problems. A description of these attempts is given by Moroni (1973). In preparation for the present longwall operation a study was performed to review existing data on the previous unsuccessful attempts, to establish coa1-and floor-strata bearing capacities in Mines Nos. 21 and

Jan 1, 1977