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By P. B. Queneau, J. E. Litz, T. P. McNulty

I. INTRODUCTION Modern hydrometallurgy has its roots in such notable successes as heap leaching for recovery of copper, cyanidation of gold ores, the Bayer process, the Oxland process for tungsten, electrorefining of copper, roast/ leach/electrowin process for zinc, and production of yellowcake from lowgrade uranium ores. Metallurgical testing techniques, sampling and analytical procedures, operating and maintenance practices, and improved methods and materials of construction which were pioneered in these processes have promoted the extension of hydrometallurgy into other applications. Periodically, new tools such as solvent extraction, resin ion exchange, and flocculants have opened new avenues to hydrometallurgists. Conversely, pursuit of more complex mineralization, the rising costs of energy and environmental quality preservation, and declining ore grades continue to create new challenges. For much of this century, it can be fairly said that practically any hydrometallurgical development moved the frontier of technology. The 1970's and 1980fs, however, have seen a significant maturing of hydrometallurgy's role in process metallurgy. Simplistically, this maturing seems to derive from a growing awareness of the strengths and weaknesses of hydrometallurgy and a determined effort to capitalize on the strengths. For example, many of us were among those revolutionaries of the 1960's and 1970's who taught that "chemical smelting" was the answer to the treatment of all sulfides. We now recognize, however, that only in very special cases can hydrometallurgy offer economic advantage over the generally less energy-intensive pyrometallurgical systems. The maturing of hydrometallurgy does not, however, signal stagnation. Important innovations are being studied and developed in most extractive areas, and a number are approaching or have achieved commercialization. From our company's perspective, that of an organization dealing with the development of the most economic solutions to metallurgical problems, innovation must be defined as the commercially successful reduction of an idea to practice. There appears to be no shortage of ideas, nor has there ever been a shortage. Many ideas now being implemented were conceived decades ago, but reduction to practice was foiled by the lack of such technology as responsive process control and economical materials of construction capable of withstanding highly corrosive or erosive environments. Commercialization of a new process is a particularly challenging undertaking. Even if technical risks are reduced to a minimum through careful and thoughtful process development, there are inevitable uncertainties in feed characteristics, variable costs, and product prices. Commercialization takes courage, both on the part of innovators who may be staking their careers or reputations and of investors who may face financial disaster in the event of project failure. This paper discusses innovative programs and recently commercialized processes which either have been discussed in the literature or disclosed to Hazen Research staff in private nonconfidential conversations with contacts in industry. Regarding this latter category of information, relative ease of communication has resulted in many of our observations being of North American origin.

Jan 1, 1985

By N. I. Fedunets

The development of variousworks on automatising of operational processes at coal¬extractive and coal-mining enterprises introduces an ever growing necessity to carry out investigations in the wide range of problems concerning the possibitity of joint functioning of different levels, which seems impossible without the use of integrated systems of passing on and prossessing the information on the basis of modern calculating machines and other means of automation. This view on the problem of automation of the enterprise operation presupposes that the structure of automated operational dispatcher control (AODC) should be very closely connected with that of integrated data processing system! In this case the AODC structure from the point of view of automation of its functions (or operations), i.e. from the point of view of informational techniques coinsides in general with the structure of dispersed information and calculating network (ICN), realizing the passing on and processing of the information as well as solving the functional tasks on the basis of local calculating networks of electrical calculating machines with correspond to different levels of AODC and located with regard to productional hierarchy of operational dispatcher control (ODC). In this approach however the use of dispersed, ICN gives opportunity to. realize the possibility of action only with realisation on the CM of algorithmic' task of ODC, when a dispatcher 'is the lastto make a final decision.. At the mining enterprises it's rather difficult for a dispatcher to make a final decision because of the great variaty of productional situations, the presence of contradictions and a number of other subjective factors which often lead to the dispatcher's mistaks causing great material losses of the enterprise. Hence the necessity arises to automize and formalize making a decision and including the expert systems (ES) into the ontour of AODC, which enables the dispatcher 2to get a neeessary advice in different situations, especially in case ofemergency on the basis of establishing the mechanism of logical layout of non-formalized data base (DB) procedures relying upon the background knowledge and experience of experts. The presently presented in this paper theory of establishing the. ISAODC on the basis of dispersed ICN and expert systems is aimed at trasformation ofoperational' tasks of the higher level into the technological ones, at solving the tasks of diagnostics and forseeing of the process of production, with a dispatcher getting an opportunity of making qualitative and effective decision concerrning the choice of operational impacts in actual time on the basis of generalization the realisation of presented conception must, as has been already mentioned, be accomplished only on the basis of the foundatoin of the united dispersed informational - calculating network of electrical calculating machines.. This includes ICN which would be operating in . different operational contours. . From what has just been said it followsthat the ISAODC Structure will conside with that of DICN (in our case) and hence all the problems of ISAODC structure would be regarded as the questions of DICN.

Jan 1, 1992

By G. van Eck, H. Smit, L. Meyer

The Cook Islands (CI) possesses within its Exclusive Economic Zone (EEZ) a massive field of polymetallic nodules representing one of the world’s largest undeveloped cobalt deposits, along with large quantities of other metals critical to achieving global energy transition targets. In February of 2022 the Seabed Minerals Authority (SBMA) of the CI granted Moana Minerals a license to conduct our nodule exploration program. This paper describes how Moana Minerals chose to approach conducting exploration activities, one of the greatest challenges to Deep Sea Mining (DSM) development and the securing of the social license to advance to eventual mining of the resources, in an unconventional manner. The remote location of the project poses logistical challenges in mobilizing to and operating in the region and is a significant cost driver. Historically, exploration campaigns mobilized large vessels from mainland Europe, the Americas, and Asia as this model works well when contemplating long duration and widely temporally spaced campaigns without the need to revisit. Moana Minerals, when considering these challenges determined a multi-year deep sea mining (DSM) exploration program conducted in such a remote location can be better optimized by the deployment of a smaller yet highly capable “exploration optimized” vessel that is dedicated to the task and is based full time in the Cook Islands. INTRODUCTION The paper describes the challenges of exploration in remote regions including the South Pacific, and how an unconventional consideration of the problem led to the solution. Completion of an Environmental and Social Impact Assessment begins with a detailed environmental scoping study, resource update sampling requirements, and engineering data and sample requirements, which identifies the exploration goals of the project and technology needed to accomplish those goals. The method walks the reader through vessel and technology selection, discusses the challenges of equipment selection considering size and capability, describes the final arrangement, and provides results from the initial exploration campaigns. We followed the project from conception through the shipyard conversion, mobilization, and initial operations in the Cook Islands. The result shows how a smaller vessel with limited budget makes a large impact on the exploration capabilities in the region while building public trust. The Anuanua Moana is the first dedicated deep sea minerals exploration vessel modified with a suite of technologies that allow it to compete technically with existing ships but operate locally in the smaller ports of the South Pacific. The unique combination of size and technical capability gives the Anuanua Moana advantages over other vessels. This paper shows the importance of the Anuanua Moana in the development of offshore exploration strategies in the emerging deep sea minerals space.

Feb 22, 2026

By Yuting Xue, Taghi Sherizadeh, Mark Van Dyke, Dogukan Guner, Khaled Mohamed

The Coal Pillar Rib Rating (CPRR) technique has been developed to assist in rib support design in underground coal mines. One major challenge of the data collection process is the measurement of coal strengths in the field. Schmidt hammer has been verified as a useful tool to determine coal strength. An alternative approach is to obtain the representative strength of coal mass by determining the coal lithotypes in the field based on the coal brightness profile by experienced geologists or mining engineers. In this paper, image processing techniques have been used to quantify the texture of coal images of different lithotypes with the purpose of classifying coal lithotypes. The coal images were collected from the pillar ribs with exposed surfaces in underground coal mines, and the coal lithotypes were identified when taking the images. The method of Gray-Level Co-Occurrence Matrix (GLCM) was used to analyze the textures of coal images of different lithotypes, and the texture parameters, such as contrast, homogeneity, energy, and entropy, were compared. The results show that the images of coal with different lithotypes have different textures, which can be quantified through the image processing. The results from this study demonstrate the potential of classifying coal lithotypes using rib photos and easing the data collection process of CPRR.

Feb 1, 2024

By A. L. Mular

Introduction The cost of grinding may be divided into a fixed equipment cost portion and an operating cost portion. The fixed equipment cost is the amount of money required to purchase the grinding mill itself. This amount may be kept separate from the installation cost which, often, is taken as a percentage of the fixed equipment cost. A good average is 43%; therefore a $100,000 ball mill would cost approxi¬mately $143,000 installed. Operating costs are variable and paid per unit time for power, liner replacement, grinding charge replenishment, labor, and mainte¬nance including major parts replacement. Such costs depend on the geographical location and will vary with the cost of labor. Operating costs are difficult to estimate. Most mining companies consider such information proprietary. This section provides a means to obtain an estimate of the equip¬ment cost of a grinding mill with a rated accuracy of±l0%. Compara¬ble methods to determine operating costs are not available. Such costs are presented in table form with suggestions for updating them. Esti¬mating the cost of liners and steel replacement is possible as described in a later section. Capital Costs of Grinding Mills Grinding mill costs have been related,124 by means of equations and corresponding graphs, to the nominal horsepower requirements of mills. All graphs are based on a Marshall and Stevens cost index for Mining and Milling of 300, where a cost index is a ratio used to estimate current prices of equipment from obsolete prices. Where (Cost Index Now) Cost Now = (Cost Then) (Cost Index Then) (I) For example, the cost of an autogenous mill that requires a 3000¬hp motor is estimated as $500,000 (Fig. 95). This was the estimated price when the M&S (Marshall and Stevens, Mining and Milling) cost index had a value of 300. If the index is currently at 400, then the estimated current price of the autogenous mill is: Cost Now = ($500,000) (400) (300) = $667,000 Most professional journals will publish current values of cost indices at least once a month. In subsequent pages, each graph of grinding mill cost vs. mill horsepower has an associated graph of capacity vs. horsepower along with a table that relates mill size to horsepower. The associated graph and the table must be used with caution, since both apply to an average ore under average conditions. Example calculations showing how graphs should be used are shown in the following. It should be stressed that the cost data incorporated herein ex¬cludes the cost of pumps, motors, lines, and classifiers, unless other¬wise stated. Costs are not direct quotes; they are the averages of quotes supplied by manufacturers and analyzed by means of regression analysis. Example 1. Calculate the power required to grind 100 tons of dry solids per hour (in a closed circuit with a classifier) when the

Jan 1, 1985

By E. J. Jacques

A typical problem in ventilation networks with multiple fan systems is the possibility of them interacting. Multiple fan systems are no exceptions in complex tunnels, and may also be met in mines where underground fans are installed. When aiming at controlling a multiple fan system in a ventilation network, e.g. with a view to maintaining an acceptable air quality level, yet at minimum power consumption, transient flow conditions frequently occur. Although in most applications these transients are short compared to the time needed to achieve the planned actions on the ventilation, one should, however, keep in mind that it is important to avoid any bouncing effect between different (adjacent or distant) fan systems. Therefore a simulation of the unsteady-state flows could allow us to learn more about the propagation of transients within the network, and their possible secondary effects Among others, one question that often is raised, is to find out in which sequence and at what time schedule each of the fans in a network should e.g. be started up? Another typical problem, into which an unsteady-state simulation could provide some insight is the following: how should the facilities of variable pitch angle and/or changeable RPM of several fans operating in parallel be handled and combined in order to obtain a flow rate that changes gradually from zero to its maximum value i.e. the sum of the individual throughput flows of all the fans. The literature is not very abundant on the topic of simulating transient flows in networks. There is no doubt that numerical models have been developed (Pollak, Christensen, 1987), most of the time for particular applications (Wala, Kim, 1985), (Tanaskovic et al., 1984), (Schultz, Sockel, 1991), etc. The aim of this paper is to present a model that also simulates one-dimensional compressible flows in unsteady-state conditions with, however, the specific intent to handle networks with more than one fan. PROBLEM STATEMENT The mathematical model chosen to describe the unsteady flows in a ventilation network is based on the dynamic and continuity equations applied to each of its airways. The following basic assumptions are made : - the flow in the airway is considered to be one- dimensional, - - the flow is assumed to be fully turbulent, and hence the ATKINSON equation for calculating the friction losses will be applied. Whether this equation remains valid for transient state flows remains an open question. However, this may reasonably be assumed since the interesting flow frequencies are low. A discussion may be found in (Kämpf, 1987) ; - the airways are assumed to have a constant cross- sectional area along their length. If obviously this would not be the case, it is always possible to subdivide the concerned airway into sections for which the previous assumption holds. Applying the basic equations of mass and energy conservation, the flow in each branch may be described by the Euler equation for Newtonian flows.

Jan 1, 1995

By Jacques H. Nantel, James F. Archibald

INTRODUCTION The use of backfill materials in underground mines has been practiced for many years and the trend indicates an increased utilization of backfill materials in the future. The authors believe that underground uranium mines will follow this trend. Classified mill tailings, approximately 65 to 70 percent solids by weight, are the most common fill materials. Cement or other pozzolanic agents can be added to the fill materials to improve their strength characteristics. Dry fill, in the form of development muck, can also be introduced in the stopes to fill the voids left by the action of mining the ore. This paper deals mainly with the assessment of the radiation properties of backfill materials originating from uranium ores processed in the milling facilities of uranium mines. The paper outlines the results of studies conducted in the laboratory and in the field on radon emanating characteristics of backfill materials utilized in uranium mines. ROLE OF BACKFILL IN UNDERGROUND MINES Fill is a structural component of any underground mining system. In general terms, the purpose of filling is to provide ground support, to make recovery of pillars possible to provide a working platform for men and equipment, and to allow for waste disposal. There are other inherent advantages to the use of backfill underground, the most important being to: a) permit mining at greater depth b) allow the adoption of highly mechanized mining techniques c) reduce dilution from wall sloughing d) minimize roof and wall failures e) allow the mining of irregular orebodies, and f) to provide better control of ventilation. The last item is of great importance to uranium mine operators. The introduction of radioactive backfill underground represents an additional source of radioactive contamination; on the other hand the introduction of backfill in the mine reduces the volumes of workings to be ventilated. As a consequence the general mine ventilation is more effective and in most cases, better air quality can be maintained in the mine. There are of course some disadvantages associated with the use of hydraulic fills in underground mines, notably: a) the handling of large additional quantities of water from the underground workings b) delays caused by the cyclical nature of the backfilling operations c) additional costs associated with stope preparation and placement of backfill in stopes, and d) "spills" caused by bursting pipes or fill escaping from fill retaining structures. ASSESSMENT OF NON-RADIOACTIVE PROPERTIES Although the radioactive properties of mine backfills are discussed in this paper many other physical and chemical properties of backfills must also be considered. These properties include: a) percolation rate and permeability parameters b) viscosity versus pulp density relationships c) size analyses d) settling times e) settled bulk density f) solids specific gravity g) void ratio and porosity h) optimal percentage solids by weight i) specific gravity of slurry j) addition of cement:cement retention and loss k) unconfined compressive strength 1) triaxial compressive strength m) shear strength (non-cemented)

Jan 1, 1981

By Peter Zhang, Todd Minoski, Gabriel Esterhuizen, Jack Trackemas, Berk Tulu, Morgan Sears

Roof stability in the belt entry is critical for safe and continuous production of coal during longwall mining. Previous studies of roof falls that occurred in belt entries have shown that the roof falls were largely associated with high in situ and longwall-induced horizontal stresses [1,2,3,4]. To properly support the roof in a belt entry, it is important to understand how longwall-induced horizontal stress changes can affect roof stability in the belt entry. Monitoring of horizontal stress changes was conducted in the belt entries of two Pittsburgh seam longwall panels oriented unfavorably to the major horizontal stress. Numerical models were also set up to investigate how horizontal stress concentrates and relieves in the belt-entry roof near the face as panel orientation changes. Both measurements and modeling results show that high horizontal stress concentrates in the belt entry roof within about 15 m outby the face. The study demonstrates that longwall-induced differential horizontal stress can be used to evaluate the horizontal stress concentration factors. The horizontal stress concentration factors change with panel orientation, resulting in high stress concentrations at orientations between 20 and 110° and low stress concentrations between 130 and 180°. Roof support strategies are given for the belt entries under the influence of high horizontal stress. For unfavorably oriented panels in weak roof conditions, supplementary support should be installed during development, and cable bolts should be anchored into a stable roof horizon. The bolting pattern should be designed to cover both entry corners and the entry center to prevent potential roof cutters and sagging.

Jan 1, 2023

By T. W. Camm, J. C. Johnson

"Most engineers are bright, hard-working, reliable, and prefer to avoid conflict. An engineering curriculum tends to self-select these characteristics. By most standards, you would expect workers exhibiting these traits to require minimal supervision. But is this true? Is this how most current engineering managers lead? Looking at some current theories on leadership combined with personal anecdotes, this presentation will look at some common misconceptions about leading engineers. INTRODUCTION Engineers are different. There, I said it. From cartoons to movies to television shows and more, there is a reason stereotypes of engineers resonate. Yes, you can find a lot individual variation among specific engineers that you may know, but they do not detract from some of the overarching commonalities that engineers are known for. CLASH OF CULTURES What distinguishes a professional? Raelin (1985), in his book Clash of Cultures, describes professionals as having superior intellectual training, maintaining their own standards of excellence, and being supported by associations that maintain the quality of the profession. Engineers obviously fit all three of these ideas: an engineering degree is still regarded as one of the most difficult to attain; we maintain our own standards both through peer-review and in academia through ABET accreditation; and through professional associations like SME to promote the discipline and foster technical growth. Six characteristics representing professional status are described by Raelin (1985, p. 9): Expertise—prolonged specialized training in a body of abstract knowledge. Autonomy—the freedom to choose the means to solving a problem. Commitment—Primary interest is in pursuing the practice of one’s own chosen specialty. Identification—identifying with the profession and with fellow professionals, both through formal associations and through peers external to the organization. Ethics—providing service without concern for oneself or without becoming emotionally involved with the client. Standards—committed to help in policing the conduct of fellow professionals. Engineers are smart—in the vast majority of cases they are hired specifically for their expertise. At a typical mine the ventilation engineer knows more about mine ventilation than anyone else on site; the same is true for the rock mechanics engineer, the explosives engineer, the planning engineer who uses sophisticated computer software—each is the expert for their particular area at the mine, that is why they have that responsibility. This can present a dilemma for the manager for each (sometimes all) of these engineers. The manager needs to keep everyone on task and focused on the objectives of the organization. Because they have reached their position by following the norms and expectations of the organization, managers tend to have a certain amount of loyalty to that organization. Engineers, on the other hand, tend to have mixed loyalties, having as much loyalty and affinity for their profession as they do for the particular company they happen to be working for at any given time. This dynamic can often lead to power struggles between the managers, based on their positional authority in the organization, and the engineers, based on their specialized knowledge (Camm, 2013)."

Jan 1, 2017

By J. Sottile, V. Androulakis

Operators of underground coal mine shuttle cars are exposed to numerous hazards including noise, dust and musculoskeletal trauma. The repetitive nature of shuttle car operation leads to fatigue-related incidents and soft tissue injuries. The poor visibility conditions, and dust and noise increase the occupational hazards to the operator, as well to other miners. To reduce the risks for all miners, towards providing a safer working environment for all workers, the introduction of autonomous shuttle cars is essential. This paper introduces a project to demonstrate the feasibility of incorporating autonomous shuttle cars in the underground coal mining cycle. The autonomous shuttle car will be able to localize itself, to map its surroundings and to navigate in an underground GPS-denied environment. It will also navigate efficiently by fusing different on-board sensor modalities, autonomously planning the optimum path and traversing around the mine while avoiding collisions with humans and other static and dynamic obstacles. This will be achieved by exploring and testing different state-of-the-art techniques and off-the-shelf components, and integrating them into existing equipment, i.e., retrofitting an actual shuttle car. Moreover, a modified mining system will be demonstrated which will incorporate the autonomous shuttle car, capable of making real-time decisions, into the mining cycle. The system will regulate the interactions between the autonomous machinery and the human dynamic, with emphasis given to the safety of the workers, and enable the real-time, remote supervision of the mining process. The focus will be on coal mines, where the room and pillar mining method is used. INTRODUCTION The growing demand for mineral supplies combined with the steady decline in the available surface reserves has driven the mining industry to mine deeper underground deposits. These deposits are difficult to access, and the environment may be hazardous to mine personnel (e.g., increased heat, difficult ventilation conditions, etc.). Moreover, current mining methods expose the miners to numerous occupational hazards such as working in the proximity of heavy mining equipment, possible roof falls, as well as noise and dust. In recent decades, the utilization of autonomous machines has evolved in the mining industry to provide increased health and safety to mine personnel and reduce their exposure to adverse conditions. Automation aims to remove the workers from the hazardous conditions which may be present in an active mining area and place them to a more comfortable and safer environment at a distance from the active mining face. Examples of incorporation of autonomous machinery in the mining industry include the fleet of more than 100 autonomous mine trucks that are employed at the Rio Tinto’s iron ore mines in Western Australia for material haulage. There are also semi-autonomous, teleoperated LHD machines employed at several mines around the world (e.g., Sweden, USA, China). However, the operation of the autonomous machinery in these cases is either partial (semi-autonomous, teleoperated vehicles) and of small-scale or occurs at surface mines where GPS significantly facilitates the autonomous navigation of them.

Jan 1, 2019

By C. Rutter, S. Nelson

"Climax Molybdenum Company’s Henderson Mine, owned by Freeport McMoRan Inc., is a panel caving molybdenum mine located 69 km west of Denver, Colorado. The mine utilizes long interconnected ore passes as part of the ore flow system. Knowing the approximate level of ore in these ore passes is beneficial for preventing increased dust concentrations in various production areas, as well as scheduling truck loading operations. Level monitoring has been achieved by using a strain gauge placed on the steel structure of the truck chute, an amplifier and a Programmable Logic Controller. This paper explains the concepts and limitations associated with using strain gauges for ore pass monitoring as well as applying proactive dust prevention and level monitoring interfaces. INTRODUCTION The Henderson Mine, located 69 km west of Denver, Colorado, is an underground molybdenum mine which uses a panel caving process to produce 18,000 tonnes per day currently. This process involves dumping ore down a series of interconnected ore passes leading to truck chutes. Trucks use these chutes to load ore and deliver this ore to an underground crusher. If ore is pulled below the lowest intercept of these ore passes, a ventilation pressure imbalance occurs which generates a large amount of dust on the levels where ore is being loaded into the tops of the ore pass. When a dust event occurs, work must be stopped until the dust settles. Once the dust settles the ore passes must be filled significantly before trucks can start pulling from the corresponding chute. This downtime and unplanned work due to dust can be avoided if the approximate ore pass levels are known. Strain gauges have been installed and tested on a truck chute at the Henderson Mine and the results of these tests have led to a series of concepts in using strain gauges to monitor ore pass levels. This paper explores these concepts and corresponding limitations and explains how the application of ore pass monitoring can be achieved with the use of strain gauges. Ore Pass and Ventilation Pressure Imbalance Overview At the Henderson Mine, there are typically two or four ore passes in different drifts that combine into one bin to create an ore pass complex as shown in Figure 1. When the level of ore is at or below the 7210 intercept (I82W), four drifts have a ventilation connection to each other and the 7655 exhaust level. A “piston effect” is created each time a bucket of muck is dumped down the ore pass. Figure 2 illustrates this phenomenon: as the loader in 621 dumps a bucket down the ore pass, the muck pushes the air in the ore pass down the 82A leg and back up the 82B leg which generates a large amount of dust. The bin regulators on 7655 cannot be opened enough to allow for this surge of air to be relieved onto the exhaust level and the dust ends up exhausting into the 625 and 627 drifts."

Jan 1, 2018

By C. E. Jordan

The Bureau of Mines investigated a simultaneous elutriation and flotation technique for separating polyethylene terephthalate (PET) from polyvinylchloride (PVC). The Tuscaloosa Research Center, through a cooperative agreement with a recycling company, devised an elutriation-flotation method for beneficiating the mixed heavy plastics portion of municipal solid wastes which is composed of polystyrene (PS), PET, and PVC. A sodium carbonate brine was used to remove the lighter PS from the heavier PET and PVC. Over 98 pct of the PS was recovered in a high purity PS concentrate containing 99.7 pct PS, The remaining PET and PVC mixture was washed to remove the brine salts that would be harmful to the flotation process. The clean PET and PVC mixture was conditioned in a solution of 45 g/t gelatine and floated in a short (l-m) column flotation cell in an upward flow of water. In a single flotation step, over 75 pct of the PET was recovered in a high purity product containing 99.8 pct PET. The bubbles attached to the PET lowered the effective density of the PET-bubble agglomerate and allowed successful separation of these agglomerates from the PVC plastic pieces. This method separated two-thirds of the mixed plastics fraction into high purity PS and PET products suitable for recycling and left only one-third of the plastics in the mixed plastics product.

Jan 1, 1992

By Joyce Lappin-Randolph

In 1977, Vertical Crater Retreat (VCR) Mining was developed at the Homestake Mine and by 1983 had become a fully integrated mining method contributing 60% to total underground production. VCR has proven successful for continuous ore blocks exceeding 55,100 tons (50,000 st) with dips greater than 60" and provides a productivity average of 39 tons (35 st) per man shift (tpms) which is 92% greater than Open Cut-and-Fill. Discontinuous ore bodies, small pods, or flat structures not amenable to bulk systems are mined with Mechanized Cut-and-Fill (MCF) and have been able to achieve a 32 tpms (29 st) average productivity. Small, low grade, remnant ore bodies were not economically viable with large scale bulk techniques and couldn't support the development required for a MCF system. As a result, Homestake began researching modified bulk mining methods to increase production rates and maintain safety, while lowering costs. A modified version of VCR with significantly diminished development was prototyped in an effort to reduce initial capital investment and expedite the production phase. This modified method is called Small Block Vertical Crater Retreat (S. B. VCR). Geology The Homestake Gold Mine is located in the northern Black Hills of South Dakota at Lead. Having been active since 1876, it now extends from the surface to the 2,440 m (8000 ft) level underground.

Jan 1, 1987

By R. L. Ziegfeld

It has often seemed to me that people are too prone to turn to new and untried materials in an effort to solve their problems, without giving sufficient consideration to the old stand-bys, except as a last resort, It?s a little like middle-aged men who are swept off their feet by the fresh beauty of a young girl without first considering the many advantages that a more mature woman has to offer. Maybe it?s because, like the older woman, the older materials have to make a determined effort to keep themselves looking young and attractive. T at?s just about the situation with which the lead industry is laced. We have to make a determined effort to keep lead looking young and attractive to industry. However, there is one difference and it is important, Lead can not only be kept looking young, but it can, in fact, actually be kept young, This results from two things. First, industry and technology are constantly changing. For example, we have known for years that the density of lead makes it ideal to stop gamma rays, but it is only recently that atomic fission as a source of gamma radiation has become an important tool of industry, That makes old knowledge about lead useful in developing a new market for it.

Jan 1, 1958

By Robert T. McKnight

Introduction The minerals exploration business, like many businesses, is faced with the problem of valuing future, risky cashflows. These cashflows are derived from those mineral deposits which have been successfully commercialized. Many deposits, however, do not have the quantities or grade of ore to be considered economic at the projected metal prices using the traditional tools of the Capital Asset Pricing Model and discounted cashflow analyses. If one calculates the future revenues, costs and cashflows of one these marginal properties, and discounted it at the appropriate risk-adjusted discount rate, it may have a negative present value. Yet such a property may still have real, positive value in the marketplace. Why would a firm pay money for a property with an (apparent) minus present value? Mining properties such as these are bought and sold in arms- length transactions on a regular basis. Why is this so? Part of the reason relates to the nature of ore reserve information. To generate cashflows, the analyst must t assume that the reserve information is known with certainty when, in fact, reserves are not known with certainty. Mineral reserves are a function of commodity price, extraction costs and the level of (usually drilling) information about the reserves. Stated, or currently known, mineral inventories may vastly understate the true state of nature. Some firms may therefore be buying a property based on a completely

Jan 1, 1988

By John M. Wootten

The development of new coal markets is -t upon the ability to utilize coal in an environmentally acceptable and economically viable fashion. Foremost in the concerns about coal utilization is the impact its combustion has on air pollution. Concerns over environmental issues, such as acid rain, are currently one of the major impediments to the development of new coal markets. The Department of Energy and the Synthetic Fuels Corporation are addressing certain aspects of the development of new technologies for the utilization of coal. However, at the present time, there is a void in the new technology development process. That void is the step from proof- of-concept to commercial demonstration. Congress has established the Clean Coal Technology Fund at a level of $750 million to fill this void. The Department of Energy, in a solicitation of interest, received over 175 proposals for commercial demonstrations of clean coal technologies. A review of these solicitations indicates that $1.2 billion worth of research could be accomplished with a federal cost sharing of $425 million or 35 percent of the total. Industry has indicated, through this response, its willingness to invest its limited funds on projects it feels have the greatest potential for the clean use of coal. What must now occur is that Congress must appropriate the monies from the fund to initiate the commercialization of these clean coal techno1ogies.

Jan 1, 1986

By William Gleason

During the past five years, mining operations have had access to press technology for piping and joint fittings that can save owners a significant amount of time when installing or replacing pipes by eliminating the need for welding or threading. Viega, with North American headquarters in Wichita, KA, entered the mining sector in 2009, adding to its already expanding industrial sector. Since then, the company?s global engineering department has paid considerable attention to its industrial division, bringing its expertise in plumbing solutions for residential and commercial buildings to the mining and mineral extraction industry. ?We have a lot of applications in the mining industry.?We have a lot of applications in the mining industry throughout the United States, Canada and Mexico and continue to expand in the mining industry,? Tom Shields, Viega?s director for industrial accounts explained. ?Since we made the decision to increase our presence in the industrial markets, we have been aggressive and more than 240 applications have been approved by our engineering department in Germany.? Getting approval from Viega?s engineering department is no small feat. During a tour of the manufacturing facilities in Ennest and Großheringen, Germany, Mining Engineering, as well as a select few other publications and clients, were shown Viega?s manufacturing process. At the Ennest facility, hundreds of millions of fittings are produced, and each one is inspected mechanically and with a laser at the end of the production line. With four production facilities in Germany and one in the United States, Viega is able to ship to anywhere in the world. The company distributes everything from fittings to stainless steel pipe.

By Vincent R. Bovino

Introduction Only a person fresh from an information vacuum could not know the status of this nation's economy. The inability of the US to compete in the world marketplace is manifested in many industries, from shoes to computer chips, from cars to copper. What industry will next fall prey to world competition? Perhaps the question should be, what insustry will next fall prey to declining productivity? American industry is being forced into an era where the focus must be on productivity, quality, cost control, and competition in the world marketplace. It is approaching a change that could rival the American Industrial Revolution. The future of the US is bright only if it can increase productivity by trying different and new ways to manage its businesses and people. Unlike the easy successes during the 60s and 70s, success in the decades ahead will depend on an ability to compete in the world market. Any operation can achieve unlimited productivity by developing the resources within its employees. As an industry, mining has harvested the earth's resources. As an industry in trouble, it now has to learn to tap human resources to release the energy and creativity in each person. Recently, I worked with a mining operation to reopen a mine and implement a different management approach. The extensive changes resulted in a 50% reduction in cash cost of producing silver (from $0.40 to $0.19/g or from $12.50 to $6 per oz). Thus, an unprofitable mine became an attractive business venture without technological changes or significant capital infusion. The operation is union-free, in spite of being in a highly unionized area. The mine implemented a real productivity improvement process called "gain-sharing." Employees now recognize their individual success is tied to the success of the business. They recognize the day of the free lunch is over for mining employees. This paper will explore three areas related to productivity: • some of the unspoken "whys" of the mining industry's paralysis and how management has caused unproductiveness in mining operations; • major components of a productivity improvement process; and • characteristics common to companies with successful productivity plans. Unspoken whys When things go wrong, everyone tends to point a finger at someone, anyone. This industry has blamed every conceivable person, corporate group, government agency, foreign government, and private group for its failures. The fault finger will not work anymore. Nobody is listening. It is a characteristic of winners in management to assume responsibility for less than acceptable performance. Excellent people tend to blame others less for problems. Everyone involved in mining should shoulder part of the blame for the industry's illness. Is the problem low prices or our high operating costs? To regain our status in the world marketplace and increase our productivity, we need to painfully and honestly talk about our mistakes.

Jan 3, 1986

By R. W. Henn

Introduction Shotcrete, by the American Concrete Institute definition, is mortar or concrete pneumatically projected at high velocity onto a surface. The term gunite is still common in literature. It is a trade name established by Cement Gun Co. of Allentown, PA, around 1911 for a dry mix of fine aggregate material, hydrated at the nozzle, and pneumatically projected at high velocity onto a surface. This article will discuss shotcrete applications, ingredients, mix proportioning, batching and mixing, admixtures, testing, and steel fiber vs. conventional shotcrete. Applications Shotcrete is used primarily by the mining and underground construction industries to temporarily stabilize an excavated rock surface until a permanent cover can be installed. It may also be used as the permanent covering material. Other uses include refractory material, architectural finishes, slope stability, wearing surfaces, repairing existing concrete structures, fireproofing, and corrosion protection of steel. Wet Versus Dry Process In the wet process, all ingredients, including water but not accelerator, are mixed the same way as normal concrete before its placement by pneumatic projection. The accelerator is added in a liquid state through the nozzle at the point of placement. In the dry process, all ingredients, including acceleration in dry form but not water, are mixed just before placement by pneumatic projection. Water is added through the nozzle at the point of placement. Liquid accelerator may be added at the nozzle in the dry process. Ingredients Shotcrete consists basically of the same ingredients as concrete with some limitations. Type I, II, and III cements are used. However, Type II seems to be used most in underground applications. This can be attributed to ground water at most sites having slight to moderate concentrations of sulfates. Air-entraining cement or air-entraining admixtures are generally not used in dry mix shotcrete. It is generally agreed that it is impossible to entrain air due to the absence of the usual concrete mixing action, and the high velocity of impingement of the material on the application surface. Air-entraining cement or air-entraining admixtures are used in wet mix shotcrete. Their use, however, is not widespread due to the placement method and the fact that high velocity air drives off most of the entrained air. Test results are not conclusive in showing any durability increase of shotcrete to freezing and thawing by using entrained air. In spite of current practice, the trend is toward additional research, with more agencies and owners requiring the use of entrained air. The philosophy behind this is that some entrained air is better than no entrained air to increase durability to freezing and thawing. The aggregates used in shotcrete are the same as those used in concrete. However, the largest coarse aggregate presently used is 19 mm (0.75 in.). A typical gradation requirement is shown in Table 1. The water quality requirement for shotcrete is the same as that for concrete. Accelerators are by far the most important admixture in shotcrete.

Jan 6, 1984

By A. Unal, H. Sevim

The utilization of high-sulfur Illinois coal by utility plants has been decreasing since the enactment of the 1990 Clean Coal Air Act Amendment. Illinois coal producers can make their coal more attractive by offering the choice of taking the coal combustion and flue-gas desu furization products from the utility plants and placing them in the abandoned sections of their mines To be competitive, however, coal producers need to select an environmentally acceptable transportation-handling-placement system through which the cost-per-ton of product disposed of can be minimized In this paper, several such systems are presented The favorable operating conditions of each system are determined in terms of distance and tonnage ranges. For a 90 kt/year (100 thousand stpy) operation, it is found that, up to a distance of 150 km (93 miles), transporting products by truck would be less expensive than using rail cars and intermodal containers. Also, a case study is given in which a cost analysis is conducted for an underground coal mine receiving products from two Illinois utility plants. At 90 kt/year (100 thousand stpy) and a distance of 40 km (25 miles) between the power plant and the mine, it is found that truck transportation and under ground placement would cost $0.090/tkm ($0.131/st-mile) and $2.98/t ($2.70/ st), respectively.

Jan 1, 1999