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By JIACHENG XIE, XUEWEN WANG, QINGBAO BAO, ZEWEN YAN

The general application of memory cutting technology to shearers is improving the intelligence of the working face, but it has its limitations. It is only suitable for conditions where the environment of coal seam is changing slowly. It compensates for the cutting height by changing the fuselage attitude, and frequently adjusts the height to control the learning cutting trajectory, but due to the problems of shearer control and height adjustment accuracy, it cannot adapt to and compensate for the change of cutting height in a timely manner, resulting in poor cutting accuracy. This study puts forward a virtual memory cutting method based on prediction of the shape of the armored face conveyor (AFC). The integrated key technologies include generation of virtual teaching cutting curve, height adjustment strategy of front and rear drums, cutting

By Barry A. Hillman

Respirable (PM-10) crystalline silica is regulated by the State of California as a carcinogen. The risk-management of this material by the State exemplifies the inherent problems in the development of regulations based on current risk-assessment practices. The influence of extremely conservative risk-assessment and risk-management can be expressed in economic impacts including the increased cost of production, reduced competition, increased prices, reduced employment and redistribution of income. This paper attempts to contrast theoretical risk- assessment and risk-management with current application using crystalline silica as an example. Based on health information pertaining to silica, the paper examines federal and State of California regulatory and public policy positions. Using current risk factors and empirical data for the Central Valley of California, the projected incidence of lung cancer in humans is examined. While such an analysis would project an extremely high incidence of lung cancer as well as silicosis, not a single case of either lung impairment has been recorded within the study area or throughout the world in the general population. This suggests that sound guidelines for the analysis of scientific information have given way to the assumption that virtually any information representing a substance as a carcinogen is to be considered valid with little or no qualification.

Jan 1, 1992

By Steve Trussell, William H. Langer

"Arizona aggregate (sand, gravel and crushed stone) producers enjoyed more than a half a century of nearly constant growth in demand for aggregates. Approximately 80 percent of the aggregate produced in Arizona is sand and gravel, and 20 percent is crushed stone (U.S. Geological Survey, 2015). Figure 1 shows the generalized distribution of potential sources of sand and gravel (yellow) and potential sources of crushed stone (other colors described below). Black dots show locations of aggregate operations.Sand and gravel commonly is produced from modern river channels and terraces although some alluvial fans and high-level paleo-river terraces also serve as aggregate resources. The gravel clasts are a mix of rock types that reflect the types of rock in the source area of the rivers. Generally processed river gravels meet stringent specifications for highend uses.Crushed stone, which makes up about 20 percent of production, primarily comes from a variety of metamorphic rocks and light-colored intrusive igneous rocks such as granite (brown areas), dark colored extrusive igneous rocks such as basalt and scoria (rust colored areas), and carbonate rocks such as limestone or dolostone (green areas). Carbonate rocks are also used in the manufacture of cement and lime.Construction and aggregate production in ArizonaBecause aggregate producers have limited facilities for storing product, stockpile changes are insignificant compared to production. Therefore, demand or consumption of aggregate in Arizona is considered to be equal to production. Production figures used in this paper reflect shipments, sales or marketable production, including aggregate used by producers to make readymix concrete and asphalt. Production figures were reported by the U.S. Bureau of Mines from 1950 until 1995 and by the U.S. Geological Survey (USGS) since then. Production figures are reported voluntarily, and major operators are the primary source for these figures. Because many smaller operators do not report their production, the figures are conservative values that provide an approximation of aggregates production activity."

Jan 1, 2015

By J. L. Thompson

The combustion of pulverized coal is a century-old practice. Many people have investigated coal dust and the residual fly ash particles that re-main after combustion. But the combustion process and fly ash formation mechanism are not under-stood. Working at our Maysville, Kentucky lime plant, the Dravo Lime Company Research team has collected samples of partially burned coal dust from the flame of a pulverized coal burner. Specimens were placed in a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). Microscopic examination of the particles, together with a large collection of micrographs of lime dust fused to fly ash particles, now make it possible to theorize as to how combustion advances through a piece of coal dust. Coal is a physical mixture of carbon-based compounds interspersed with bits of ash-forming materials, primarily alumina-silicate compounds. The alumina-silicate materials are commonly in angular nodules measuring 100 A to 700 A across their major dimension. It would appear that if the coal particle is in a well mixed gas stream, combustion starts at the surface and advances radially toward the particle center. With poor gas mixing, it is common that combustion moves from one end of a particle and advances on a broad front almost normal to some axis. In either case the combustion process and ash-forming mechanism are the same. As combustion occurs the carbon-based compounds oxidize in a highly exothermic reaction. Heat from the re-action melts the alumina-silicate nodules causing them to flow together and coalesce into an open sponge-like structure. As melting continues surface tension of the liquid and free surface energy causes the sponge-like structure to simplify into fewer, larger pores. Most likely the lighter molecular weight hydro-carbons burn before the heavier species. This means that as the melting ash structure is metamorphosing to a single large pore, there continues to be out-gasing throughout the structure due to combustion. Surface tension will form a spherical piece of fly ash if the ash material is liquid for a sufficient period of time. Out-gasing from combustion of the heavier hydro-carbons will provide internal gas pressure to keep the particle spherical until it freezes.

Jan 1, 1978

By Lynda T. Holden, Philip L. LeHoux

Barneys Canyon Mine is a 1.8 million t.p.y. gold heap leach operation near Salt Lake City, Utah. The gold recovery plant has been operating since September of 1989. Carbon elution is done at atmospheric pressure with a high temperature caustic solution. No cyanide is used in the process. Operating experience is discussed.

Jan 1, 1990

By A. W. Fletcher

A nickel-copper sulphide concentrate was treated in a pilot plant at Warren Spring Laboratory during 1961, by a hydrometallurgical roast-leach- solvent extraction process devised to cleanly separate the metal values, and produce acid sulphate liquors containing the metals. It is shown that 86 percent of the nickel and 95 percent of the copper could be leached from the calcine, after a sulphatizing roast on finely ground flotation concentrate. Iron was removed from the leach liquor by limestone neutralization with a small loss of values. Copper and nickel were separated by solvent extraction with naphthenic acid in kerosene after partial neutralization of the iron-free liquors with ammonium hydroxide. Hydrogen sulphide and chlorine were used to remove zinc (and residual copper) and cobalt impurities respectively. The recovery of pure copper and pure nickel, by electrowinning, from the acidic solvent extract strip liquors finally produced, appears technically feasible.

Jan 1, 1964

By Madan M. Singh

Although roof bolting has been a major means of strata support for nearly two decades, little attention has been directed towards the design of bolt Installations. The variables involved are interdependent and their study complex. However, some simple tests may be employed to serve as guides to the efficient design of roof bolt systems. Local conditions are continually varying and are important to pattern design. This paper discusses such considerations and suggests techniques which may be employed to effect improved roof control with bolts.

Jan 1, 1967

By A. H. Baldo

Covers a very broad spectrum of problems and solutions. The problems are multitudinous and their solutions are sometimes simplistic, sometimes ingenious and sometimes within a very broad interpretation of the law. However, one thing is quite certain: the problems and their solutions will have a direct impact upon corporate and personal well being. First of all, why does one mine in a foreign land? Since the Bronze Age, when ancient man discovered the metallurgy of copper, tin and zinc, intrepid souls have been wandering afield searching for and exploiting those mineral deposits which would create wealth and security for his city-state or community.

Jan 1, 1981

By C. E. Capes

The continuous balling? operation whereby a moist particulate mass is tumbled in a horizontal revolving drum with recirculation of the undersize product can be extremely unstable. Product and recycle rates are subject to wide fluctuations. Although the problem seems to be well-recognized, there is little published information or quantitative data readily available, especially in relation to industrial-scale circuits. Probably the best available published results are in the Russian literature, an illustration of which is given in Figure 1. These data, taken from a study') of some of the factors which influence the stabilization of the pelletizing process, illustrate the wide variations in circulating load and circuit productivity which may be encountered over a period of operation. The problems of balling circuit stability may be traced to random seed or nuclei generation and uncontrolled agglomerate growth. The situation is analogous to that in crystallization processes where (4 considerable attention is given to nucleation control. Traditionally attempts have been made to optimize system and operating variables to stabilize the balling process. A supplemental approach which is taken here is to build on the considerable

Jan 1, 1975

By W. W. Kephart

The glass container industry is the largest producer of glass in the United States. As of this writing, there are approximately 89 active domestic production locations. In 1984, the industry shipped 11.8 million tons of glass containers. Approximately 70% of this production was clear or flint glass, 20% amber, 7% green, and the remainder miscellaneous colors. Although the production of nearly 12 million tons of glass is impressive, anyone following the industry over the last five years is aware that the industry has changed from a pattern of growth in the 1970's to one of maturity in the 1980's. Some observers, less generous, perhaps, have described the 1980's as a period of decline. In 1981, there were 119 production facilities which produced 13.2 million tons of glass the previous year. This equates to a 10% reduction in glass container production from 1980 to 1984, with a corresponding impact on the segment of the industrial minerals producers serving the container glass industry, as shown in Figures 1 and 2.

Jan 1, 1986

By Vivas

Goldcorp is one of the largest gold producers in the world with projects in South, Central and North America. Goldcorp?s flagship operation is Peñasquito, a world class, polymetallic deposit that started production in 2010 and is one of the largest mines in Mexico. Since the early stages of the project, Goldcorp has used the most advanced technologies available to maximize its value. However, the implementation of optimum mine plans has been challenging to put into practice. This is due to the fact that the mine operation involves more complexity than the plans usually reflect. This challenge is an industry-wide issue that presents opportunities for improvement. This article discusses the mine planning methodologies and procedures used to connect long-, medium- and short-term planning strategies in order to bridge the gap and produce optimum mine plans that can be practically implemented in the field.

By David M. Abbott

"The picture of the baby surrounded by the number of (usually) pounds of a variety of mineral products a newborn will use in a lifetime has been widely distributed over the years, both on the web and as business cards that could be distributed to anyone. Figure 1 shows a typical example. I have included a slide of the mineral baby in various lectures over the years, particularly in my lecture “Industrial minerals: much used, little recognized.” The mineral baby with associated estimated lifetime mineral quantities is updated every year. I collected a set of past mineral baby pictures to examine the changes in the quantities of the various mineral products over the years.The mineral baby was introduced by the Minerals Information Institute (MII) in 1999 and became known as the “MII Baby.” SME took over MII in 2008 and continued publication as the “MII Baby” until the merger of MII with SME’s GEM program in 2011 to form SME’s Minerals Education Coalition (MEC). MEC is now the publisher. Figure 2 is the 2016 version of the mineral baby. The repositioning of the picture of the baby from lying on its back to crawling reflects a major design change to help emphasize that SME’s MEC is now the mineral baby’s publisher.Data sourcesThe data used to prepare each year’s mineral baby comes from the National Mining Association, which collects the preliminary annual mineral commodity data from the U.S. Geological Survey (USGS) and other sources. This preliminary data becomes available late in the first half of each year. The life expectancy data for each year comes from the Center for Disease Control’s “Data and Statistics by Topic” and the population data comes from the U.S. Census Bureau’s “Quick Facts” tab.The source mineral data is compiled using metric tonnes as the basic unit. The quantity of of each mineral is the apparent U.S. consumption each year."

Jan 6, 2017

By K. Huttu, A. van Wageningen

"The Kittilä underground mine in northern Finland is extracting one of the largest known gold deposits in Europe. Kittilä achieved commercial production on May 1, 2009, becoming Agnico Eagle’s first mine to open outside of Canada. The Kittilä orebodies were initially mined from two openpits – Suuri and Roura – and underground operations were added in October 2010. The pits were mined out in November 2012, so mining is now entirely underground in the Suuri and Roura deposits. Additional, small openpits will mine any remaining near-surface reserves in the future.The Kittilä Mine is located in the Lapland region of northern Finland, approximately 900 km (560 miles) north of Helsinki and 150 km (93 miles) north of the Arctic Circle. With a mine life estimated through 2034, Kittilä is Agnico’s longest-life mine.The mine’s proven and probable reserves contain 32 Mt (4.7 million oz) at 4.6 g/t (0.13 oz/ st) gold. Ore has been mined from underground since 2010. The original 3 kt/d (3,300 stpd) operation underwent an expansion project to increase the throughput capacity of the mill by 1 kt/d (1,100 stpd), starting by the end of 2014.The region around the Kittilä Mine is underlain by mafic volcanic and sedimentary rocks of the Kittilä Greenstone Belt oriented nearly vertical. This greenstone belt is similar to those hosting Agnico Eagle’s Canadian deposits in Quebec’s Abitibi region and Nunavut. At the contact point between ironrich and magnesium-rich rocks lies a 100- to 200- m (330- to 660-ft) thick structural zone known as the Suurikuusikko Trend. This trend hosts the Kittilä deposit, where multiple mineralized zones have been traced over a strike length of more than 25 km (15 miles).Most of Agnico Eagle’s work has focused on a 4.5-km (2-mile) segment of the Suurikuusikko Trend that hosts the five main zones of the known gold reserves and resources. From south to north they are: Ketola, Etela, Suuri, Roura and Rimpi.The ore at the Kittilä Mine is refractory, making gold extraction relatively difficult because the gold is generally locked inside the two main sulfide minerals – arsenopyrite and arsenic-rich pyrite. Only about 4 percent is very fine-grained “free gold” (not locked in sulfide grains) and easier to extract. Most of this free gold is found in the outer, oxidized or eroded sections of the ore."

Jan 1, 2015

By VASU GANGRADE

Large-opening underground stone mines pose significant ground control challenges, including the risk of massive pillar collapses. These collapses can result in dangerous air blasts characterized by tremendous force and high velocity. Estimating the velocity of these air blasts proves challenging due to the absence of accurate air velocity instruments near the mine portals. To address this issue, this paper proposes a novel approach that leverages closed-circuit television camera footage from the mine. Specifically, it employs the optical flow algorithm implemented in Python to estimate the velocity of the air blasts, providing a valuable tool for assessing and mitigating risks in such mining environments.

Feb 1, 2024

By Yi Luo, Jian Yang, YUJIA LIAN

Scale physical models, constructed according to the principle of similarity theory, are widely used to simulate the mining disturbances to surrounding strata and to evaluate the effectiveness of implemented ground-control techniques. This technique has also been used for studying mining-induced surface and subsurface subsidence. The movements of the observation points installed on the physical model at different mining stages are currently measured using a total station, which is time consuming and inaccurate, especially on small-scale models.

By James E. Lonergan

Linear goal programming is a multi-objective optimization technique where the constraints of a linear programming formulation of a problem are considered as additional objectives. The optimal solution is the one that comes closest to satisfying all the objectives. An interactive computer program was written to utilize this technique in solving the feed blending problem faced by power plants de- pendent on multiple sources of coal supply. This program determines the amount of coal from each supplier to utilize in the blend. Examples of the use of the program in both long and short term coal procurement planning scenarios are given.

Jan 1, 1984

By R. W. Salmi

The authors discuss the cooperative efforts by Minnesota Ore. Operations and Research; from the earlier development, testing and installation of fine shear screens in the Minntac Step III concentrator to the most recent testing and operating data that has resulted in the installation of Derrick Multifeed sandwich deck screens in Minntac Steps I and II. Pilot-plant test results that were obtained at the Coleraine, Minnesota Research Laboratory are also reported and demonstrate the effects of feed rate and feed percent solids on sandwich screen performance with two sizes of Minntac fine screen feed.

Jan 1, 1984

By Thomas E. Newman

This paper is a case study using new laser-terrain-mapping technology by EagleScan, Inc., for creating topographic maps. Holnam, Inc., has used this technology to create maps and volumetric calculations of several mines in the United States. The information is superior to conventional methods through accuracy, manpower, time, and cost. Holnam, Inc., was the first cement manufacturer to use the Digital Airborne Topographic Imaging System (DATIS?). The technology uses the DATIS? to produce high-resolution terrain maps and volumetric assessments of any area. DATIS? is a mapping instrument that integrates (1) a Light Detection and Ranging (LIDAR) instrument to measure terrain elevation using laser light, (2) a large-format digital camera, (3) a relative position Global Positioning System (GPS) to measure aircraft position, and (4) an Inertial Measurement Unit (IMU) to measure aircraft attitude. The DATIS? can measure up to 220,000 elevation samples per mil. The system continually collects data on the aircraft's position and measures the time for each laser pulse transmission to return from the ground, giving each sample a GPS reference. The system can operate at night, in overcast sky, and during high-wind conditions and can measure terrain below vegetation cover, unlike standard aerial photography used for traditional surveying and mapping. Surveyed ground-control panels are no longer necessary with this new technology, and only one ground GPS base station located within 60 mi from the aircraft position is required. A computer elevation-point data file is created with the x, y, z coordinates of each laser elevation sample. With this file, CAD engineering programs can create topographic maps that rival products using conventional aerial mapping techniques. Volumetric measurements of stockpiles and pits are also available due to the high density of points collected from an area. This new technology radically changes the turnaround time for map users, giving a product in the format used by today's cartographers. The time line from flight to maps is measured in days instead of weeks.

Jan 1, 1999

By Robert L. Frantz

The various facets of university-company cooperative activities and the opportunities for collaborative research for the mineral industries are presented in this paper. The advantages and disadvantages of various alternative research funding arrangements for the researcher, the university, and the sponsoring corporation are discussed. Examples of university-industry cooperative research programs are briefly outlined. The concept of a cooperative mining research program is presented. The improvement of performance through techno- logical developments and human skills may well be the greatest competitive edge available to the U.S. mining industry. In this regard, the need for new endeavors between industry and universities can hardly be overemphasized.

Jan 1, 1984

By R. E. Cook

"Mineral deposits require substantial amounts of energy to transport and be processed into usable form and, as such, present a real processing challenge in that the deposits are never homogeneous and orebody compositional characteristics are all over the map. Extracting the desired mineral(s) from the deposit at sufficient profit margin, despite severe fluctuations in market price, requires process automation architecture capable of supporting an integrated enterprise solution. Such an architecture will encompasses the activities of individuals, process units, process areas, plant level activities, mine management and business planning, and accounting systems. Key to the automation process is the aspect of value generation. This article brings together the various requirements for the automation of a mining enterprise and presents the different aspects of how to obtain value across the entire mining operation.Minerals’ processing sites are historically long lived, with 20-year life-of-mine not uncommon and 75 years not unheard of. Considering that hardware technology advancements are introduced every six months, or less, it is prudent to select process automation systems that adhere to “open” industrial standards versus proprietary based systems. In the minerals processing industry, the key to survival is driving the cost of production per unit volume to the lowest possible level and provide enough profit to sustain operations. Control system architecture and business information technology are rapidly becoming important tools in the quest for productivity. Getting key dynamic business performance information at the right time to the right person or process unit is crucial to successfully achieving corporate goals. The process automation architecture selected must, therefore, be able to integrate to the various networking enterprises and business systems.The mining industry is generally known as an extractive industry that is physically oriented with respect to operations and the activities in which workers engage. Large numbers of people performing manual tasks in difficult surroundings, produce variable outputs. But times are changing – and so are industry best practices. While the nature of work still consists of activities such as ore extraction, ore movement, ore concentration, refinement and logistics, automation innovations are starting to change the nature of many of the production steps. The industry has transitioned from requiring more physical activities by workers to more information management, automated control and collaboration within the operation. Humans are good at situational intervention and nonlinear reasoning and do best when empowered with an overall production perspective. Machines and automation are good at repetitive functions, steady state operation, and managing transitions. Thus, a combination of advanced technology solutions, reliable and useful information and full human contributions are necessary to mining operations for value generation."

Jan 1, 2015