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By Carl Erickson, James Hislop

INTRODUCTION As practiced today, longwall mining is a mechanical version of an established mining system. The equipment for longwall mining consists of four basic units: roof supports, face conveyor, winning or mineral-getting ma¬chine, and stage-loader conveyor. The system mines relatively thin slices of mineral across a predetermined face length in a virtually continuous sequence. As the winning machine cuts, the mineral is loaded automatically onto the face conveyor. In turn, the face conveyor is pushed over into the newly cut track by hydraulic rams attached to the conveyor and the roof supports. The roof supports then are lowered individu¬ally from the roof, advanced to the repositioned con¬veyor, and reset to the roof. At the end of the pass, the longwall cutter is pushed over, and a slice is taken in the opposite direction, so the system repeats itself. Fig. I illustrates a typical longwall mining system. The principle behind the longwall mining system is that the roof is supported only immediately adjacent to the worked seam, keeping the blocks of immediate roof clamped securely from the face to the rear of the sup¬ports. At the rear of the supports, the roof is allowed to fall and break up, with the swell of the broken material eventually establishing an equilibrium in the strata be¬hind the mined area. Fig. 2 illustrates the principle of longwall support. There are two distinct types of longwall mining. The longwall retreating system is the most common in the United States, South Africa, and Australia. The longwall advancing system is the most common in the re¬maining industrialized countries such as Britain, Ger¬many, Poland, and the Soviet Union. The longwall retreating system comprises a mining panel, where the roadways that form the head entry (end at which mineral is delivered from the face con¬veyor to a stage-loader conveyor) and the tail entry are predriven before the longwall units starts production. In the longwall advancing system, the longwall unit makes the head and tail entries as the face advances, utilizing various techniques to prevent the entries from being destroyed as they are left in a consolidating gob area. Fig. 3 illustrates the comparative approaches of the longwall retreating and advancing operations. As with most other underground mining systems, there are many variations on these two basic systems, using combinations of the systems that are dictated by

Jan 1, 1982

By R. A. Wyman

"The froth flotation process was patented by E.L. Sulman, H.F.K. Pickard, and John Ballot in 1906 . . . . . . . . . .James M. Hyde installed the first froth flotation process in the U.S., about August 1, 1911, at the Basin Reduction Co. plant, Basin, Montana . . . . . . . . . .By 1914, 42 mining companies were operating or experimenting with the flotation process . . . . . . . . . .The period 1930 to 1960 saw the application of flotation spread to nonsulphide ores and become the key factor in the economic production of many industrial minerals". So states FROTH FLOTATION, 50th Anniversary Volume, published by AIME in 1962. It is interesting, to observe that the Mines Branch, now part of the Canadian Department of Energy, Mines and Resources, was established in 1907 through an act of Parliament entitled, "The Nines and Geology Act". In 1911, a mineral dressing group was formed and a laboratory was constructed. By 1921, an engineer was devoting full time to industrial mineral processing problems.

Jan 1, 1971

By K. A. McDonald

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

Jan 1, 1994

By K. R. Griffin

Explosions in underground coal mines have been a serious safety concern since the advent of mining; despite significant technological advances, they are still occurring. Parameters such as barometric pressure, geological changes, and changes in ventilation can contribute to an explosion. These factors can be monitored with available and developing technologies to create algorithms that predict when explosions are more likely to occur. This paper reviews current underground atmospheric monitoring systems and related regulations around the world. In addition, suggestions for improvement and implications for explosion prevention are discussed.

Jan 1, 2011

By R. C. Burtan

Long before recorded history, man began to dig into the earth's crust in a never ending search for useful materials. It is well known that more than half of the earth's crust is composed of silicon dioxide (SiO2), also known as silica. Silica and silica-containing material have a great many uses in modern society. This material, however, is potentially an extreme health hazard. Silicosis: Not a New Disease Centuries before the Christian Era, Hippocrates wrote of a lung disease common to those who mined in hard rock. He was obviously describing silicosis. It is also apparent from ancient writings that the Egyptians were aware of this malady. Dioscorides also wrote on this subject in the fifth century B.C. It is undoubtedly the oldest and best studied of the occupational lung diseases. Silicosis was certainly described by Agricola in his De Re Metallica published in 1556. Here he described lung disease among hard-rock miners. The original document was written in Latin and then translated in 1912 by Hoover and Hoover. One of these translators was Herbert L. Hoover, a former US president who once made his living as a mining engineer. More recently, there are numerous references in medical literature in the 19th and 20th centuries relating silica exposure to silicosis. There are specific references to mining in hard rock, as well as to sandblasting and a host of other industrial exposures. In 1919, Winslow described standards for measuring the efficiency of exhaust systems in polishing shops using sandblasting. These standards were equally applicable in the mining industry. As early as 1920, Winslow explored the efficiency of certain devices used to protect sand-blasters against the dust hazard. These devices were equally applicable in the hard-rock mining industry. The medical community recognized the silica health hazard in the early 1900s. Middleton described the illness in the British Medical Journal in 1929. He noted the danger to health at that time. D. Hunter mentions in his book, The Diseases of Occupations (1969), the monumental work of Merryweather in 1936, in which he surveyed the silicosis risk in Great Britain. He showed statistically that the average employment length of sandblasters who ultimately died of silicosis was 10.3 years, compared to 40.1 years for all fatal cases, irrespective of occupation. Sandblasting and hard-rock mining and drilling, obviously, are very hazardous occupations. Weil and Zisking of Tulane University wrote in 1975 that "it was known as early as 1935 that the course of silicosis is much more rapid in sandblasters than in miners or foundry workers. This can be explained by the fact that sandblasters are exposed to an almost pure siliceous dust containing high concentrations of respirable particles within the range of 1 to 3 micron size." Protecting the Worker The medical community recognized in the early 1900s the need for proper protective equipment for all of those who worked with siliceous materials. Middleton, writing in 1929, said: "The worker is then protected by a close fitting helmet with an air feed, much as in the case of an underwater diver. In spite of these precautions, cases of silicosis among sandblasters are being met with today. It is a matter for serious consideration whether a substitute, such as steel or iron grit, could not be used to replace the siliceous grit as the abrading material." C. E. A. Winslow, a professor of public health at Yale School of Medicine, and others wrote of the need to protect sandblasters by

Jan 7, 1984

By F. G. Heivilin

We are no longer short of viable Rare Earth deposits. As little as 2 years ago China mined and produced 97% ofthe world?s rare earths. Only a few deposits were in an advanced stage of exploration and development. Now Technical Metals Research (TMR) Gareth Hatch *5 reports that 347 deposits are being developed by 265 companies down from 440 on July 6th. Their Index of Advanced projects lists 45 projects in 14 countries. They will sustain the world for centuries to come and many good deposits are yet to be found. The problem is mining 14 elements in balance. Each of the deposits listing production in the chart has a unique set of minerals which they think will give them a cost advantage. Which of these will make it to production is a question. Most of the Advanced won?t be mined soon, but which ones? China is still in the driver?s seat in Light Rare Earth production (LREO) with one deposit with 35 million ton Baiyunebo deposit in Inner Mongolia which is part of a working iron ore deposit. The number of HREE deposits have been reduced and they attempting to eliminate unpermitted mines. This report will tell you what a Rare Earth is, how rare they are, why they are important, and where they are being developed which includes Australia, the United States, Africa, Greenland, Brazil and Canada.

Feb 27, 2013

By Kadri Dagdelen, Lee J. Zamalloa

Modern surface mining operations are always seeking for minimizing costs while increasing production rates, among the optimization of other specific tasks that have an impact on the economics of the mine. Specifically, the cost related to the production fleet operation (shovels and trucks), the maximization of the overall performance of the equipment, and the uncertainty to meet the goals at the end of the operational time horizon are always topics of discussion with no apparent simple answer. On the other hand, truck-shovel dispatch systems based on Linear/Non-Linear Programming Algorithms have been in operation since mid-1990’s with different levels of success depending on the correct arrangement of operational resources and the complexity of the mine, but having in most cases some important shortcomings related to the way these systems deal with the decision making of the operational objectives, being necessary to have a human agent (dispatcher) to guide the system when the operational parameters change, creating the possibility of suboptimal decisions due to the human factor. This paper discusses the implementation of a novel methodology based on AI techniques to assist in the decision making of the best goal selection when operating a Fleet Management System, taking into consideration time periods as variables and integrating them as part of the analysis, providing a better overview of the forecast plan completion with respect to previous production numbers and evaluating best alternative to handle future events to minimize losses or maximize profits, resulting in better truck assignments, minimum shovel idle times and overall productivity improvements of the operation at the end of the time horizon.

Jun 25, 2023

By Delbert L. Keenon

The principal concepts of computer control and automation have been successfully applied in industries world-wide, The enthusiasm generated by the proponents of computer control, and the apparent mystery enveloping the techniques of computer control, have caused attention to be focused on this infant industry from all quarters. Consequently, the motivation to "computerize" may be the hope that computers will solve all economic problems. The truth remains that not only have there been monumental successes, but there have been some colossal failures. This paper will attempt to outline a generalized guide to computer control and present methods for avoiding some of the major pitfalls. Since the investment required for computer control systems has been drastically reduced in the past year, small operations will likely find that computerized process control is attractive in areas where it has never been considered before, The discussion presented here is intentionally non-technical and directed towards those who may soon find they have a possible application for a control computer. The primary purpose of computer control is to reduce expenditure and increase profits by improving the quality of product, increasing the efficiency of operation, reducing the materials and man hours required or a combination of these. Success or failure to reach the desired goal depends, to a large degree, on a well-planned approach. This includes recognizing a possible computer application, properly defining the job which is to be accomplished, evaluating computer systems, selecting a capable manufacturer, and following through with sound systems engineering and programming.

Jan 1, 1965

By R. R. Klimpel

The industrial processing of ores containing precious metals such as gold is generally very mining site specific, e. g. McQuiston and Shoemaker (1985), vanZyl et. a1. (1988), Fuerstenau and Hendrix (1990), and Hausen et. a1. (1990). The variety of various mineral processing techniques employed is extensive and includes size reduction, size classification, gravity separation, roasting, cyanidation, chemical and/or bacterial leaching, ion exchange and/or solvent extraction, and froth flotation. Gold occurs in the earth's crust on the average in very low concentration estimated by various sources to be between two and five parts per billion. For a specific ore deposit to be considered as an economic source of gold, generally a concentration of near one part-per million (one gram / Mton) or more is required. From a mineralogical viewpoint, gold often occurs in its native or free form. However, it can also occur as gold compounds of telluride, antimony, and selenium contained within either sulfide minerals such as pyrite, arsenopyrite. and pyrrhotite or, to a less extent, within silicate, oxide, and carbonate minerals. In many locations, alloying of gold with silver is found. The optimal processing method for recovering gold is determined by many factors such as the mineralogy of the gold bearing minerals as well as the associated mineralogy of the gangue minerals, the type of liberation profile of the gold bearing minerals upon' size reduction, and the particle size of the gold itself. Free or native gold particles can vary in size from the extreme of large nuggets to very finely disseminated gold associated in a complex sulfide mineral matrix. Typically free gold particles of several hundred microns or larger are efficiently recovered by one or more of a number of gravity based techniques due to the large specific gravity differential of gold (19.3 to 15) versus typical gangue minerals (5 to 2.7). When gold is associated with a sulfide (usually pyrite) matrix, historically most industrial plants involving size reduction and subsequent liberation have operated in a size range of 50 to 80 percent less than 75 microns. Grinding finer than this has been normally not economical unless the ore has a high gold content in the feed ore.

Jan 1, 1998

By Birger Schmidt

INTRODUCTION Conceptual design of the first Exploratory Shaft (ES-I) for the Nuclear Waste Repository in Basalt (NWRB) began in July 1981; detailed design began in February 1982, and was largely completed by December (RKE/PB, 1983). The intent was to begin shaft construction by January 1983. The site had been prepared at that time, a construction manager selected and on board, the starter hole excavated and lined, and steel casings were under procurement. Government policy changed, however, and construction was halted before the drill rig started turning. Construction is now planned to begin in 1988. ES-I is a part of the site characterization program for the NWRB. The shaft will be used to develop production data and related information relative to drilling shafts at the site near Richland, WA, and to provide access to the repository horizon for site characterization and testing. The early program called for one shaft and some 330 m (1000 ft) of drifting. The program has since expanded to include a second shaft (ES-II) and more extensive drifting and testing. Currently, both shafts are planned to be 1.8 m (6 ft) in finished diameter, but studies are underway to determine if the second shaft should be larger. The drilling method was selected for shaft construction primarily because it offered a significantly shorter construction period than conventional shaft sinking using freezing and grouting. The finished drilled shaft will be lined with a continuous steel lining. Personnel are safer during construction with a drilled shaft than with a conventionally sunk shaft. The drilling method

Jan 1, 1987

By Gary Brierley, Lok Home

"The majority of tunnels for civil engineering applications are now being constructed using some form of mechanical excavation. Beginning in the 1960s with rock tunnel boring machines (TBM), the tunneling industry has introduced both earth pressure balance (EPB) and slurry pressure balance (SPB) soil machines; mixed soil and rock machines and a variety of different mechanical devices for the construction of small diameter tunnels. Over time, these machines have become more powerful and more adaptable to a wider variety of ground conditions; so much so that tunnels are now being constructed in ground conditions and in the vicinity of third-party impacts that would have been considered beyond the state of the art just 10 years ago. Figure 1 is an example of a mixed ground crossover TBM used successfully at Mexico City’s Túnel Emisor Poniente II.All of the above is highly advantageous for the tunneling industry, but it has also placed a much higher level of risk on the performance characteristics of the tunneling machines, on the contractors operating those TBMs and on the manufacturers of those machines. Most of the risks for a tunneling project are associated with creating the space inside of which the finished facility will be constructed. In order to create that space, the tunnel contractor must make many decisions about the best way to excavate the ground, the best way to control the ground at the face of excavation and the preferred method for supporting the ground around the tunnel in a manner that is safe for the workers and stable with respect to all of the overlying and adjacent existing structures. If it is proposed to use some form of TBM in order to build the tunnel, then the TBM becomes central to all three of these activities and becomes an integral part of managing the risks associated with these activities."

Jan 9, 2018

By Sam Rosenblum

The anomaly ratio is obtained by dividing the analyzed value of an element by the anomaly threshold value of the element. The sum of anomaly ratios for all anomalous elements in a sample may be compared with similar sums for other samples, so that the samples having the greatest anomaly-ratio totals can be recognized easily. In partial or full-suites-of-ore-elements the use of anomaly ratios is more meaningful than analyzed values because the ratios quickly indicate anomalous elements and call attention to samples and localities that should be investigated.

Jan 1, 1980

By Youngtak Ko, Wonnyon Kim

Korean contract Mn-nodule field in the NE equatorial Pacific is composed of seven sectors showing average water depths of 4,513 - 5,025 m. Of the various factors controlling the property of Mn-nodules, water depth has a potential linkage to chemical composition, shape and abundance of nodules. To clarify such a possibility, we review more than 20 years of research data in one of the northern sectors (hereafter KR1) where there is a marked contrast in water depth. High-resolution seabed mapping clearly separates a northern part from a deeper southern part, cutting across the middle of the KR1. In terms of nodule occurrence, manganese nodules in the deeper north are comparatively larger (2-4 cm) with rough surface (t-type) and discoidal shape (D-type), while those in the south are generally small (<2 cm) with smooth surface (s-type) and irregular shape (Itype). In addition, the nodules in the north have higher metal contents including Cu, Mn and Ni. Such connections of water depths to nodule occurrence and metal contents are commonly observed in the Korea licensed Pacific nodule fields. However, the relation between nodule abundance, size and water depth may be a different story. In KR1, nodule abundance and size are probably controlled by morphological features especially in the north. Seamounts in the north continuously provide rock fragments as new nuclei for the nodules. As a result, the nodules can not grow larger than 2 cm and show the shapes of newly formed nodules (i.e., smooth surface and irregular shapes). Such an interpretation is supported by anomalously high backscattered intensities in the side-scan sonar image map of the north, which possibly reflects a younger generation of magmatic activity.

Sep 1, 2014

By Kevin DeSomber, Scott Bird

Larger grinding mills continue to utilize large gear-driven drives or electrical wraparound drives. The panel will include presenters from operations with large mechanical and electrical drives. JIM HANDLEY: Before we get to the third and final session, I want to introduce my co-conspirator for this session, John Mansanti. John is manager of milling with Newrnont Gold Company, Carlin, Nevada, and was very active in securing participation in this innovative symposium. I&apos;m Jim Handley and I&apos;m with Cyprus-Amax Minerals at the Sierrita copper and molybdenum mine. Our third presentation is titled "Geared Up or Wrapped Up?" I hear this topic discussed, but never at great length. I think that&apos;s because the opinions are fairly strong and diverse, and people generally aren&apos;t reinforced properly in their arguments. The first person to enlighten us on this topic is Scott Bird. He has more than 20 years with Kennecott, is a graduate in metallurgical engineering from the University of Utah, and is currently operations superintendent and deals with this phenomenon every day.

Jan 1, 1998

By V. McLemore, N. Dunbar, K. Donahue

There are three principle lines of evidence that indicate the clay minerals found in the Goathill North (GHN) rock pile at the Molycorp mine are predominantly a product of hydrothermal alteration, not weathering. The unweathered drill core and samples from GHN have similar types and abundances of clay-mineral groups based on XRD analysis. Chemical analyses from the electron microprobe reveal similar chemical compositions for the hydrothermal alteration clays in drill-core samples and clays found in the rock pile. Textural evidence gathered from petrographic and microprobe examination also suggests a hydrothermal origin for clay minerals.

Jan 1, 2007

By David C. Girard, Larry Williamson, Leonard R. Benson, Ronald E. Bizzarri

On the east side of Washington DC, the DC Water & Sewer Authority is developing a Facility Plan for the Anacostia River CSO Control Projects, including 8 to 12 miles of CSO storage/conveyance and flood relief tunnels and associated facilities. The project includes major technical and non-technical challenges, including: completion under a Federal Consent Decree schedule; large diameter (estimated 25 to 35 ft) soft ground tunnels and shafts up to 200 ft depth; operations without use of active flow control systems; and close coordination with several major public and private construction and development projects that are being advanced in the project area.

Jan 1, 2007

By F. Mielli

Mine operation managers are constantly tasked with identifying new ways to produce more, while using less. Mine effectiveness and reliability is the foundation of improving operational performance. Timely decisions need to be made in order to identify production waste. Intelligent data needs to be visualized in real-time. Operational events need to be captured with impacts quantified and root causes identified. Unfortunately, complex information technology solutions often have a very poor success rate, with some reports suggesting 30 percent of complex projects are canceled before completion.

Feb 27, 2013

By Peter F. Mataich

The phosphate mining industry is a highly competitive one, one in which survival depends on the plant&apos;s ability to produce at costs equal to, or below, the competition. The solution toward getting costs down is usually one of scaling up the plants to get the most tons through at the lowest possible cost. Control of these plants has been an art. Few of them are well instrumented because until a few years ago reliable instrumentation was non-existent. International Minerals and Chemical Corporation was a pioneer in applying computer techniques to ore reserves analysis and mine planning and the success in these areas led to the question of whether we could not extend the advantages of computer processing into the plant itself. There was a great deal of doubt on the operator&apos;s end that this could be done successfully because of the lack of instrumentation and the fact that plant control was largely an art that was learned only after many years of experience. However, in 1965 the instrumentation picture began to look up and the new generation of process computers just coming on the market were considerably lower in cost than the previous ones. A preliminary study of the installation costs and the probable benefits that could be realized from computer control convinced us that a process control computer should be seriously considered for a new phosphate mining plant which was being designed.

Jan 1, 1969

By F. A. Baczek

The Electroslurry TM electrowinning concept has been incorporated into a process flowsheet for recovering copper from smelter flue dusts. The process has averaged 96% recovery of the copper as high-grade electrowon while at the same time removing a majority of the impurities that degrade drawn copper as a result of recycling flue dust and liberator cathodes: The dust is processed through several stages consisting of leaching, copper precipitation, Electroslurry TM electrowinning and waste liquor treatment. The process may be integrated into a smelter operation and become an effective and feasible means of maintaining good product purity.

Jan 1, 1980

An incremental-analysis-based stope design and cutoff grade calculation method was developed for an underground metal mine project. Traditional stope design methods are typically very time consuming and lack consistency and accuracy by manually drawing stope shapes. For quick reserve calculation and economic analysis, a new method named "3D incremental analysis based stope design" was created for mine-wide stope designs. The key idea of this method is to replace engineers&apos; manual checking of each incremental ring with one calculation of all the rings, and to build the final stope shape with the maximum values. This process was realized through a 3D ring grid setup and proper naming conventions for rapid calculations. With this unique but practical method, multiple options for a mine design were completed within a short time before the final selection of optimal cutoff grade and best stope designs for the project.

Jan 1, 2012