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Semiautogenous (SAG) ball mills are being increasingly used today for the coarse grinding of a range of ores, including gold, copper and iron. Larger mines are demanding mills with larger throughputs. This has led to some remarkable developments in mill diameters and installed powers. Conventional design principles - mills with trunnion bearings - have reached their limitations. This article describes one SAG mill with a slide-shoe arrangement and Krupp Polysius' Combiflex twin drive. In August 1997, the world's largest SAG mill with a slide-shoe arrangement was commissioned in Queensland, Australia, operating as a wet mill. The inside diameter is 10.4 x 5.1 m (34 x 17 ft) effective grinding length. The 1.36-ktlh (1,500-stph) SAG mill is driven by two Combiflex drives (twin drives with 2 x 5,500-MW or 7,375-hp installed motor power) in conjunction with a girth gear (outside diameter 11,890 mm or 468 in.). Commissioning of the SAG mill was completed with no notable technical difficulties. The plant runs continuously except for planned maintenance stoppages and process-specific reasons. As this article is written, the machine has been in operation for about 8,000 hours without major problems.

Jan 1, 1998

By T. W. Camm

"As engineers, we are trained to use logical, rational problem solving to insure our mines operate at maximum efficiency. We tend to use the same technical approach to design safety into all mining systems. This works well for machines, but not so much for the human component. Recent insights in the field of behavioral economics provide useful ideas for addressing the fact that we are driven by emotions more often than by rational thought. Understanding the nonrational aspect of human behavior is an important piece of any safety system design. INTRODUCTION The most common economic model is based on humans making rational decisions; that given the proper information, we will make a logical, rational decision based on what is best for ourselves (Ariely, 2009, p. xviii). In many cases this is an accurate description of how we make decisions. As an engineer, I was trained to apply the precision of mathematics and logic to solve problems. As an engineering professor, I now teach this approach to bright young minds preparing them for a life of professional effectiveness as practicing engineers. That said, we are not only rational. Daniel Kahneman, winner of the Nobel Prize in Economics, describes a model for how we think (Kahneman, 2011). System 1 is the part of our mind that is fast, intuitive, and emotional; while our logical, slower, and deliberative mind is System 2. According to Kahneman’s model, System 1 runs automatically, most of what you think and do originates in System 1. System 2 takes over when things get difficult, including the application of math and logic, and the resolution (or avoidance) of conflict. As engineers, we would typically assume that we operate in System 2 mode most of the time. This is where the model becomes useful, for Kahneman points out two important aspects of the dynamic between the two systems in our mind. First, System 1 has biases, systematic errors that lead to answering questions with an easier answer (rather than a right answer) before System 2 is engaged. Second, we can be blind to the obvious, and also be blind to our blindness. Complicating things further, System 1 cannot be turned off (Kahneman, pp. 24-25)."

Jan 1, 2015

By Yuting Xue, Lihong Zhou, DAVOOD BAHRAMI

The paper discusses the use of machine learning (ML) to develop a predictive model for determining the location and size of underground mine fires using simulated ventilation data. The study highlights the importance of prompt fire location determination for effective firefighting strategies and reducing injury risks. The ML model was trained with simulated data and achieved an accuracy score of 0.920, which improved to 0.962 by grouping closely connected airways.

Sep 1, 2023

By A. Dell’Era, E. Ciro, C. Lupi

The paper explores the recovery of indium via electrowinning from sulfate baths, focusing on the impact of different cathodic supports (AISI 316L and nickel) on process parameters such as electrolyte composition, current density, and temperature. The study compares productivity, morphology, and structure of indium deposits on both cathodes, finding that nickel cathodes generally yield better results.

Nov 1, 2023

By Donald A. Dahlstrom, Wai-Ping Kam

The mineral industry and individual processing plants are large consumers of energy. While energy conservation has received some attention in the present Federal Administration National Energy Strategy proposal it is obvious that the mineral industry should also continue to emphasize energy consumption reduction for important economic savings alone. As indicated by other studies, comminution is the largest single consumer of energy in the mineral processing plant (1.3% of total electrical energy consumption in the U.S.A.).1 Fine grinding is the largest portion of this amazing statistic. While substantial energy savings have been demonstrated by new machine developments and improved control methods, undoubtedly there are additional areas in comminution where substantial progress can be made. Some time ago, the U.S. Department of Energy published a report on "Comminution and Energy Consumption" by a committee composed of experts in the field of comminution from industry and academia. They identified the following potential for energy savings by specific areas? Classification device design 9-13% Comminution device design 3-16% Control 9% Grinding additive 3-6% Materials 3% It is apparent that the classification device had the first or second highest savings potential. Obviously, serious research consideration must be given to this technology area. A series of three papers have previously been written on the subject of two stage classification research work for ball mill operation by the authors. Accordingly, a brief review will be made. Previous Research Results on Two Stage Classification The hydrocyclone was selected as the type of classification equipment for this study as it represents by far the majority of the devices used in ball milling. While four different hydrocyclone circuits have been proposed by others,3 only two were considered in this work as illustrated in Figure 1. Flowsheet A is truly counter-current in nature in that the product from the ball milling circuit is taken from the first stage overflow

Jan 1, 1992

By John C. LaScola, Gerald L. Finfinger, Michael A. Trevits

Methane gas is an ever-present problem facing the underground coal mining industry. Mine operators are mandated by law to maintain safe concentrations of methane gas within the mine environment. Ventilation is the method of choice used by all mine operators to reduce gas concentrations. When gas emissions are such that ventilation alone cannot control the gas, methane drainage methods must be applied. In the 1970’s, there was a concern that unprecedented gas emissions would be experienced as mine operators began new developments in the deep and gassy Blue Creek and Pocahontas No. 3 Coalbeds. Such concern was well founded as significant gas volumes are being emitted as these mining operations mature. In 1971, the U.S. Bureau of Mines began to tabulate and track the change in mine emissions. These data were extracted from the underground coal mine quarterly air quality-quantity inspections performed by the Mine Safety and Health Administration. At that time, approximately 6560 Mm3/d (231.7 MMcfd) of gas were emitted from 430 underground coal mines. It was determined however, that the mines emitting less than 2832 m3/d (100 Mcfd) contributed only 2.1 percent of the total daily gas flow. In 1988, underground coal mines emitted 8350 Mm3/d (294.9 MMcfd) from 487 mines. This report evaluates the changing nature of U.S. mine gas emissions over the last 18 years.

Jan 1, 1991

By Yueyue Ding, Yuanhui Li, Zhengrong Li, Pengfei Yu, Kunmeng Li, Zhipeng Xiong

The overburden responses in gently inclined orebody mining are different from those in horizontal orebody affected by the orebody dip angle. In particular, the mining-induced stress presents asymmetrical distribution characteristics spatially, resulting in stress concentration and large-scale pressure relief phenomenon in the surrounding rock. As a result, frequent ground pressure disasters such as roof collapse and barrier splitting occur frequently. Moreover, the ground pressure evolution law and the interaction between stopes in multistope mining are complex. The effective ground pressure control measures cannot be taken due to unclear understanding of the evolution of stress and displacement fields, justifying the investigation of the distribution and evolution of underground pressure for safe and efficient mining.

Jun 1, 2023

By Alan L. Mierke

West Virginia's economy has been closely linked with coal. West Virginia is consistently one of the top three coal-producing states. Its 149 Mt (164 mil¬lion st) produced in 1992 represented 16.5% of total US coal production. In recent years, the state's economy has experienced a diversification away from its traditional employment base of min¬ing and heavy manufacturing. However, the coal industry remains an integral part of the lives of West Virginians. Coal is mined in 33 of the state's 55 counties. In many of these counties, the coal industry is the largest private employer and contributor to the economy. West Virginia has three major coal-producing regions. The northern region produces coal high in gas and sulfur content (steam coal). It is consumed primarily by utility and industrial markets. The southeast region produces high-grade coal low in sulfur content but high in carbons and Btu (metallurgical coal). The southwest region produces metallurgical and steam coal. The high-grade metallurgical coal is used in the production of coke for steel manufacturing. Metallurgical coal also comprises the majority of coal exported from the United States. During 1993, West Virginia was the country's largest exporter of coal, accounting for 44.5% of total US coal exports.

Jan 1, 1995

By F. Gray

Diamond tool fabricators expect strong growth in most applications for 1995 and 1996. Overall growth projects range from 8% to 10%. Diamond grinding is forecast to grow between 5% and 8%, while cubic boron nitride grinding should grow between 10% and 12%. A strong automotive industry is a major factor in this projected growth, as is continuing demand for other durables

Jan 1, 1995

By Faruk Oksuz, Dave Schiemann, Matt Trotter, Mike Padilla, Miguel Sanchez, Carmen Scalise

"Chicago’s Tunnel and Reservoir Plan (TARP) is a nearly $4.0 billion and over 30 years long program and arguably the largest and longest combined sewer tunnel and reservoir system in the world. Recently, a massive tunnel construction is underway for connection of the McCook Reservoir to the existing TARP tunnel system. Once completed in two stages in 2017 and 2019, the reservoir will hold 38 billion-liters (10 billion-gallons) of combined sewer overflows (CSO) and flood waters from the city of Chicago and over 20 communities in Cook County, Illinois. McCook Main Tunnel will connect Chicago TARP’s Mainstream Tunnel to the McCook Reservoir. Connecting two 10-meter (33-ft) diameter tunnels at 92 meters (300 feet) underground has not been a simple task for the McCook Tunnel Project participants, the project owner U.S. Army Corps of Engineers (USACE), local sponsor Metropolitan Water Reclamation District (MWRD) of Greater Chicago, designer Black & Veatch, and the contractor, Kiewit Infrastructure Company (Kiewit). Yet alone excavating and lining massive size tunnels, the team is also challenged with live tunnel conditions in TARP Mainstream Tunnel that carries CSO and flood flows from city of Chicago which runs full during rain events and must remain in service at all times. The project is a noteworthy feat for engineering and construction with the upcoming installation of world’s largest underground wheel gates for flow control within the tunnel. In this paper, we describe one of its kind elements of this major tunnel system along with key design and construction considerations, specifically for the live tunnel connection which is a rare occurrence in the tunneling industry. INTRODUCTION The McCook Main Tunnel system consists of a 10 m (33 ft) finished diameter and 490 m (1,600 ft) long hard rock tunnel constructed from a 27.5 m (90 ft) diameter and 92 m (300 ft) deep main gate and tunnel construction access shaft. The gate shaft houses six high head 4.4 m by 9 m (14.5 ft by 29.5 ft) wheel gates to be installed in the bifurcated and steel lined section of the tunnel. The tunnel also includes portal and energy dissipation structures as it daylights into the reservoir."

Jan 1, 2016

By John J. Sammarco

"The mining industry has made great strides in making mining safer and reducing the occurrence of mine disasters. Nevertheless, sometimes miners encounter smoke while trying to escape from a mine. Underground miners use different visual cues to help them escape from a smoke-filled environment. Foremost, miners look for primary and secondary escapeways that are typically indicated with reflective markers of various colors, with at least 11 colors available from manufacturers. Federal regulations require that escapeways be marked, but they do not specify the colors to be used. Thus, no standard color code exists and some colors can be more difficult to see in a smoke-filled mine.Researchers at the National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) tackled this problem by taking a human-centered approach to provide miners with better visual information that would improve their ability to see escapeway markers in smoke, thus enhancing their ability to self-escape. What marker colors does your mine use?Does your mine use blue retro-reflective markers to indicate primary or secondary escapeways? Is your mine ready to purchase new or replacement retro-reflective markers? Color is important and blue had the poorest visibility as determined by OMSHR’s recent research investigating the visibility of markers in smoke. OMSHR researchers are not alone in their interest to improve a miner’s ability to escape - specifically when their efforts are hampered by smoke. For instance, there is a LinkedIn Mining Safety subgroup called "Standardized Color Code for Escape Ways and Returns in Underground Mines," and a recent National Academy of Sciences report recommended the development of humancentered technologies to enhance self-escape from underground mines. The mining industry has a common goal of helping improve miner safety, especially when it can be done by way of a simple and relatively low-cost solution of using escapeway colors that are more visible."

Jan 1, 2014

By Joel Lööw, Johan Larsson, Stig Vinberg, Malin Mattson Molnar, Mats Jakobsson, Jan Johansson

The mining industry is undergoing rapid transformation, driven by technological advancements, sustainability concerns and demographic shifts. This transformation will put more younger people in management positions. This study provides valuable insights into the leadership behaviors of younger and older managers within a large Swedish mining company, highlighting the importance of managerial experience and targeted training programs to foster effective leadership, particularly in the context of change management. The findings emphasize the need to create work environments that support managers to develop their leadership, contributing to improved employee well-being, operational efficiency, and adaptation to the changing demands of the modern mining sector.

May 1, 2025

By Meyer Klein

Decision theory is the formal theory of the logic of decisions in view of the decision maker's objectives, preferences, I beliefs, and available information, It usually deals with weighty economic problems involving irrevocable (or costly to reverse) decisions. Capital investment planning problems constitute an instance par excellence for application of the decision theory concepts. Decision theory as it is presently conceived has evolved in recent years. At first it concentrated on decisions in the face of total lack of information and on games with intelligent adversaries. The results of these efforts proved theoretically interesting, but practically of little applicability. In the last few years, stress has shifted to the introduction of subjective probabilities and preferences, and the results have been eminently successful in applications both in government and with- in business firms in the resolution of complex problems.

Jan 1, 1970

By Susumu Ukita

We have developed first a conveyor belt for transporting large lumps, i.e. Rock Belt successfully, in June 1976. The First Rock Belt had been delivered to Myodani site of Kobe City Developing Board in Japan, and its' successful operation has attract keen interests in customers from over the world as well as Japan. However, this First Rock Belt was removed in arch '81, viewing it has satisfactory expired its service life of about five-year, and also original location of this belt become to be far from the site due to long-years earth collecting work. Taking this opportunity, we introduce the Second Rock Belt applied for Rock Belt Loader as ell as three types of application of our Rock Belt working for rationalization of quarry of major company in Japan, and, view the prospect of Rock Belt:

Jan 1, 1981

By John J. Friel

The addition of dolomite to iron ore pellets improves their high-temperature reduction properties primarily by increasing their reducibility and raising their softening temperature. In this study we prepared dolomite-fluxed pellets from three different concentrates; Hibbing, a magnetic taconite, Knob Lake, an earthy hematite; and Carol Lake, a mixture of specular hematite with magnetite. The composition n of the concentrates is given in Table I. The pellets were subjected to standard physical tests and the following reduction tests: low temperature degradation, swelling, softening, and thermogravimetric analysis. Petrographic examination and electron microprobe analysis allowed us to evaluate the effect of composition and firing on the phase assemblage. Further, we were able to interpret the test results in terms of chemistry and microstructure. This approach enabled us to determine which fluxed composition best suited each of the concentrates.

Jan 1, 1980

By Daniel C. McLean

Chemistry plays a more important role in milling operations than is generally recognized, particularly in fluid- solid separation processes. Chemical aspects are also very important insofar as plant water quality is concerned, and in the manner in which this water quality effects plant design and operation. Aside from the inherent chemical characteristics of plant water, the mineral preparation industry is becoming increasingly more dependent on the use of mining chemical reagents--relatively new to the coal industry, but items of I standard usage in complex metal recovery plants. These chemicals have many useful properties and can produce significant improvements in operations and metallurgical efficiencies when used properly and intelligently. They can produce poor results and sometimes severe losses when used improperly. Most reagents are relatively expensive on a per pound basis, hence costs can be excessive if they are used wastefully or inefficiently.

Jan 1, 1968

By P. L. De Bruyn

[According to the Young equation, SG = SL + Coso, the equilibrium contact angle depends on the values of the three interfacial tensions involved. A solute promotes wetting, i. e. a decrease of contact angle if it decreases.LG and/or YSL or if it increases SG. Dewetting, the important step in flotation is, promoted if the solute increases y and/or SL or decreases. Most solutes used for wetting or dewetting are, positively adsorbed at all interfaces involved and consequently according to the Gibbs equation lower the interfacial tensions. Wetting is therefore expected to occur if LG and SL are more affected by the solute than SG. Dewetting on the other, hand demands a greater decrease of SG than that of SL (and of LG). See P. L. de Bruyn, J. Th. G. Overbeek and B. Schuhmann, Jr., Mining Engineering (1954) P. 519.]

Jan 1, 1960

By R. Perez

The consumption of grinding media forms a significant part of the operating cost of a mineral processing plant. An estimated half billion pounds of steel in the USA and over one billion pounds in the world are consumed each year in wet grinding alone. However, there is some conjecture as to the interacting roles of abrasion and corrosion. In order to provide a more complete picture of the conjoint action of abrasion and corrosion, marked ball tests were conducted on different grinding ball compositions in a laboratory ball mill and the metal losses were measured on varying the conditions, i.e., pH, PO2, in wet grinding a Cu-Ni gabbroic rock and compared with taconite grinding. Ball wear rates ere discussed with respect to ball composition and microstructure and the varying conditions used in the grinding tests.

Jan 1, 1984

By David S. Young

All pigments and extenders or fillers whether organic or inorganic fall into the following broad general classes: I. Colored II.-White III. Black IV. Metallic A pigment- is any particulate matter that is essentially insoluble and chemically unaffected by the media into which it is dispersed. According to this very broad definition, colored pigments, white pigments, fillers, extenders, and functional pigments would all be included. The particulate size range would also be quite broad ranging from very fine colloidal particles (~0.01µ) to relatively coarse particles (~100.0µ). This broad definition is usually subdivided into more practical divisions which tend to relate the classification of the pigment to its primary function in the system in which it is used. Hence, the word extender implies that its major purpose may be to extend the system.

Jan 1, 1985

By W. E. Hale

The Institute of Applied Geology (I.A.G.), a joint project sponsored by the University of the Philippines, the Philippine Bureau of Mines and the United Nations Development Programme (Special Fund) undertook during 1965-66 a number of field projects in Northern Luzon Island (Fig. 1). These field operations were of a two-fold nature: during approximately six weeks an orientation survey, involving, geology, geophysical surveying, and geochemical prospecting, was conducted over a partly developed, disseminated copper deposit at Sto. Nino (Fig. 1). The Sto. Nino study demonstrated (Hale and Govett, 19677 Govett and Hale, 1967) the feasibility of geochemical prospecting relative to other exploration methods for the location and delineation of disseminated copper occurrences, the major source of metal in the expanding mineral industry of the Philippines. A vein occurrence at Suyoc (Fig. 1) was similarly subjected to

Jan 1, 1968