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By James R. Brown

Mount Isa Mine should be regarded as a large mining complex rather than one mine. This arises from the geography, variety and extent of the orebodies, the mining methods, and the use of 14 shafts for ventilation distribution. A brief resume is presented here since comprehensive descriptions of lead-zinc mining methods {11}, copper mining methods {2 }{3}, geology 241, stope fill {5} and ventilation techniques {6}{7}, have all been published in the last five years. Mining extends over a north-south strike length of 2.5 miles (4 Ian) with a maximum width across dip approaching 3 200 ft (1 Ian). Current mining is to a depth of 3 150 ft (960 m) with the ore hoisting shafts extending 660 ft (200 m) deeper. The composite longitudinal section, Figure 1, shows a representational disposition of the copper and lead-zinc-silver orebodies in the central shaft complex where the main service and hoisting shafts are located. To the south the X41 man and materials shaft provides access to the copper area. The mine layout is typical of high tonnage track- less mines, utilising a large diesel fleet, raise- borers and some large diameter hole stope drilling. Mining methods include sublevel open stoping, slot and massfire, and a trial vertical crater retreat in the copper ore, and sublevel caving, sublevel open stopes with and without rib pillar recovery, and mechanised cut and fill in the numerous lead orebodies. All ore reports to one of the three crushing systems located below 19 level in the central shaft complex. Copper ore is hauled exclusively along the 19 level computer assisted Rockflo haulage system, and lead-zinc-silver ores report via central orepasses from Granby haulages on 13 level and 15 level. Tonnages hoisted during the 1977178 financial year were 5.0 million for copper at 3.2%. and 2.3 million for lead-zinc-silver at 7.8%. 6.3% and 7.06 oz/ton (216 g/tonne) respectively.

Jan 1, 1980

By Justin Brown, Michael Kobler, Dave Ragland, Bob Shufflebotham

PROJECT OVERVIEW As the sun-bronzed San Diego students strolled casually to class, mining crews from Atkinson Construction were working only 9 meters below the surface. The330 meter long, 11.3 meter diameter squat ellipse NATM tunnel is part of the9.3 kilometer Mission Valley East Extension Light Rail Transit (MVE-LRT) being constructed for the San Diego Metropolitan Transit Development Board (MTDB). The SDSU segment of the MVE-LRT was awarded to the Clark Construction Group, the parent company of Atkinson Construction for $82.7 million. URS CORP was the prime designer and Hatch Mott MacDonald performed the NATM tunnel design. The construction managers were Washington Infrastructure Services with Underground Construction Managers, EPC Consultants, and ILF Consultants. A NATM tunnel design was chosen as the most cost-effective way to minimize disruption of the university activities. The tunnel passes close to several buildings and directly below access roads, tennis courts and a baseball field. The NATM method of conventional mining uses shotcrete for ground support often reinforced with steel orplastic fibers, welded wire mesh and lattice girders. The tunnel runs from a cut and cover box up a 4.2% grade in a 217 meter radius left-hand curve with several spirals and ends at the underground station 330 meters away. The depth of cover varies from 16 meters near the west portal to nine meters at the station. The design called for a two-pass system with a primary lining of 300 mm shotcrete with lattice girders at 1 m centers and two layers of welded wire mesh. The lattice girders are used primarily for profile control and are not considered a structural element. The top heading was designed to be excavated in one of three excavation sequences depending on ground conditions and depth of cover. In sequence one excavation, the top heading is excavated in two halves with a one-meter separation. In sequence two excavation, a side gallery is advanced 8 or more meters ahead of the

Jan 1, 2003

By L. Rudolphy, P. Tähkiö

"The cPlant is a modular flotation plant which has been designed to minimize capital expenditure and risk. The plant is based on a number of standard modules, for both flotation and ancillary equipment, which can be configured to give the required flowsheet for the ore being treated. All of these modules can be rapidly deployed and erected onsite, minimizing not only engineering time and site preparation but reducing the time taken to get the plant up and generating revenue. Given the paradigm shift in flotation circuit design that has been employed in the cPlant it may allow smaller, previously uneconomic deposits to be exploited and create a more cost efficient upgrade route for existing plants. This paper introduces the cPlant and presents a case study comparing EPC cost and development timing of a cPlant against a traditional flotation circuit design. INTRODUCTION In the development of any mining project the cost associated with process plant engineering, equipment procurement and installation can affect the financial viability of a project. This is of special significance for smaller scale mining projects which perhaps don’t have the mine-life or revenue generation to justify the payback on a modern processing facility. Listening to customer feedback and understanding the challenges that small to mid-sized projects can face lead Outotec to the development of the cPlant. Modularization of mineral processing plants isn’t a new idea with a number of examples being reported in literature for gravity gold (Cabot, Trudel and Cabot, 2001; Gray et al., 2006), dense medium separation (September and Abate, 2006) and even hydrometallurgy (Saario et al., 2013). All these plants have been developed to try to improve on the traditional economics associated with fixed processing plants. Using standardized modules to construct a plant reduces engineering time and design costs which can both be beneficial to the outcome of a project. In addition the modular nature of the plant lends itself to transport to remote sites and rapid installation with only minimal site preparation required. A plant of modular design also has several other advantages over its conventional cousins. Firstly it is relatively easy to expand by duplicating existing modules. Secondly the modules can be treated as building blocks for the process and rearranged if a change in conditions requires flowsheet adjustment. Thirdly, there is potential to disassemble and remove the modular units at the end of the mine life. The ability to easily disassemble, re-pack and transport the plant to a new location not only is important to the long term environmental footprint of an operation but can also be seen as a bonus to an operator that has a number of small ore deposits. If applied in this way modular plants have the potential to create a whole new operating model for previously unviable ore deposits."

Jan 1, 2016

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 C. William Parisi

Since the introduction of mechanical mining, some 35 years ago, a great deal of effort has been expended by the coal industry to solve the coal dust problem. The original concern was the possibility of a dust explosion or the propagation of a gas ignition; however, in recent years it has come to be recognized as a possible 'health hazard as well. In the middle thirties, the Pittsburgh Coal Company began an intensive study of the dust problem to determine the dust levels created by the various cycles of operation in mechanical mining and to make a comparison with those of hand loading operations. Numerous dust samples were collected with a midget impinger and it was found that dust counts varied from 38 to 268 million particles per cubic foot during hand loading and from 96 to 227 million particles per cubic foot during mechanical loading. The study indicated that the source of underground dust in coal mining could be classified as primary or secondary. A primary source is one associated with appreciable degradation of size, that is, where most of the fines capable of becoming air-borne are produced. A secondary source is one in which most of the fines have been produced at some previous operation and are in such condition that they can become air-borne. Cutting, drilling and blasting are the operations which produce the primary dust. Secondary dust is formed by operations which include; loading, transportation and discharge at transfer points. The study showed clearly that the coal cutting operation was responsible for the greatest amount of dust and that the amount of dust produced varied directly with the speed of cutting; type and dullness of cutting bits; and the distance the cuttings had to fall to the floor. The information obtained from the study enabled our company to decide on a course of action and the direction to follow. With the cooperation of mining machine manufacturers, water tanks with a 200 gallon capacity were built into the machine trucks and were provided with a pump driven by a small motor. A length of 1/2" water hose carried the water from the pump to the two water spray nozzles located at the front of the machine. Water was delivered to the machine tanks by water cars which were filled on the surface or from an underground water supply. It was during these early days that wetting agents were introduced into the water system. Our studies revealed that wetting agents did little better than plain water in the abatement of the dust problem. It was found that when using a wetting agent less water was required to obtain the same results but we could not take advantage of this fact because it was almost impossible to keep the smaller nozzles open to reduce the amount of water being used.

Jan 1, 1967

By James J. Fallen

In this paper we are going to look at some things that may happen to the industrial minerals industry in the next decade. First, some concepts and definitions. What are industrial minerals? Not everyone agrees on an answer to this. So let's look at some of the opinions. Some say that industrial minerals are non-metallic minerals. As you well know, metallic minerals are used as a source material for metals. Copper, lead, and zinc are extracted from metallic minerals. But, some metallic minerals are also used for other reasons. Bauxite is used as a source of alumina and aluminum. It is also used as proppant in well drilling, as an abrasive, as a refractory material, and as a source of aluminum-based chemicals. So bauxite is both metallic and nonmetallic. There are other examples, too. Bastnasite is a source of rare earth metals and alloys but its concentrate is used in fluid cracking catalysts. Phosphate rock is an industrial mineral when used for fertilizer, but it is also the source of phosphorus. Ilmenite and rutile are sources for titanium dioxide pigments as well as titanium. So the nonmetallic designation is not adequate to define industrial minerals. Some say industrial minerals are called such because they are consumed in industry. How about your cat's litter box? Is that industry? Huge amounts of montmorillonite, attapulgite and other sorbtive minerals are pelletized and calcined to make animal litter. Doctors are trying to get people to cut down on their salt consumption. They are against people eating industrial minerals. When diamonds are a girl's best friend, they are not industrial minerals; when they are grinding and polishing media, they are. These examples show that industrial minerals are not exclusive to industry. Regardless, here is my list of industrial minerals: Abrasive Materials - Bentonite Antimony (Oxide) - Borates Asbestos - Calcium Carbonate Attapulgite - Diatomite Ball Clay - Dolomite Barite - Feldspar Bauxite (and Alumina) - Fire Clay Fluorspar - Pyrophyllite Fuller's Earth - Rare Earths Graphite - Salt Gypsum - Sand and Gravel Kaolin - Silica Sand Kyanite - Soda Ash Limestone - Sodium Sulfate Magnesite - Spodumene (Lithium) Magnetite - Sulfur Mica - Talc Nepheline Syenite - Titanium Dioxide Perlite - Vermiculite Phosphates - Wollastonite Potash - Zeolites Pumice There is some overlapping. Fuller's Earth takes in some attapulgite, bentonite, and other minerals, depending on the market. Some would like to distinguish industrial minerals by the market emphasis they receive compared to fuels, metallics, and precious metals. But even there, strict logic fails. Some industrial minerals are commodities. They are sold on a price basis against industry product specs, usually in large volumes. Phosphate rock, potash, sulfur, salt, soda ash, and other materials fit this category. Some are almost custom-designed for end-use and meet performance specs. These are sometimes called functional or specialty industrial minerals. Examples of these are ground calcium carbonate, water-washed kaolin, cosmetic grade talc, filtration grades of diatomite, perlite, and vermiculite. To determine prospects for the decade ahead, regardless of our

Jan 8, 1984

By D. A. Gulley, L. J. MacDonnell, William A. Vogely

INTRODUCTION Environmental impacts are most commonly associated with air and water pollution. Not- withstanding this fact, to many people the primary disruption caused by mineral extraction is the change in the character of the locale. That is, the environmental impact of mining includes, but is not limited to, the generation of residuals. The dramatic transformation of wilderness or rural land often creates strong reactions to mineral development. Thus, the basic issues of land use management are a useful addition to environmental discussion. In this section, we take up a discussion of federal, state, and local land use management regimes, along with a brief introduction to the potential role of economic analysis. Elsewhere in this volume, land management issues are discussed from other orientations, and the interested reader may wish to look there as well. Locatable Minerals on Federal Lands Legislation and Administration: Access to hard-rock minerals on the public lands is governed by the General Mining Law of 1872. This law declares that "valuable mineral deposits in land belonging to the United States . . . are hereby declared to be free and open to exploration and purchase . . . ." In order to initiate rights, prospectors are required to physically stake claims of specified sizes and shapes following basic procedures set by federal law which may be supplemented by the individual states. Rights to these claims are protected at the exploration stage so long as actual possession is maintained and diligent exploration activity is underway. If a valuable mineral deposit is discovered on the claim, the claimholder earns the exclusive right of possession as against private parties so long as the claim is properly maintained. To maintain this exclusive right the claimholder must per- form $100 worth of labor or improvements, known as assessment work, on each claim every year and make related annual filings with the U. S. Department of the Interior. If the existence of a valuable mineral deposit can be demonstrated, and other legal requirements are met, the claimholder may receive a patent giving full title to the claimed land, including the surface in most cases. The purchase price is either $2.50 or $5 .OO per acre. The Mining Law has remained largely un- changed by legislative amendment during its now more than 100-vear existence. However, while the law itself has not changed, its interpretation and administration have changed considerably. Written at a time of rapid western expansion of the U.S. following the Civil War, the intent of the law was to promote mineral development by inviting unrestricted prospecting and by selling the lands containing mineral deposits at a minimal charge. As federal land policy shifted from one of rapid disposal into private ownership to one of retention and management for a number of uses, mineral patenting requirements have been administered more strictly. The most critical issue concerns what must be demonstrated to establish the existence of a valuable mineral deposit. The so-called "prudent man" standard was established in the case of Castle v. Womble (19 L.D. 455 (1894)):

Jan 1, 1985

By C. J. Bise

Virtual reality (VR) is a concept in which the human experience of perceiving and interacting with a computer-modeled environment is achieved through the use of sensors and effectors. It is an advanced form of computer graphics. The images are generated based on where the user looks and how the user moves. As personal-computer-based (PC) instruction gains acceptance as an innovative approach to providing safety training, VR can provide a multisensory, rather than merely a multimedia, mode of presentation. New technology continues to be introduced into the mining industry to meet the productivity needs of coal and noncoal producers. There is also an increased need for more innovative training of mine workers. New technology and equipment designs often affect the basic causes of accidents. For example, the development of cabs and canopies for underground coal-mine equipment has reduced the number of accidents related to roof falls and rib rolls. However, safety-training specialists then had to focus on the machines themselves, because the modifications had the potential for causing "pinch-point" accidents. In fact, although the overall physical demands on mine workers have diminished, there has been an escalation in the concerns about trauma from repetitive physical activity. Thus, health-and-safety training specialists have shifted their atten¬tion to the recognition, evaluation and control of workplace hazards (Hancock and Hill, 1995). Recognizing that the spatial relationships of a workplace convey more information about hazards when experienced rather than described, trainers agree that simulation is the method of choice. Unfortunately, until recently, simulation systems were either simple software programs that did not come close to portraying the real experience or were complex hardware systems (such as flight simulators) that did, but at a cost of millions of dollars (Fritz, 1991). However, researchers and training specialists are excited about an emerging approach to work-force education based on virtual reality. VR is also described as cyberspace, immersive simulation, artificial reality, telepresence, virtual environment or virtual world (Meyer and Dunn-Roberts, 1992; Peterson, 1992). It represents a group of concurrent advances in computer and interface technologies. They enable an individual to interact in a multisensory way with a computer-generated environment. To achieve this, a typical VR system incorporates a computer that contains the necessary databases for producing realistic images and audio; a head-mounted display (HMD) or screen for viewing the images; and a three-dimensional controller, joystick or data glove for interacting with the computer-generated environment. If virtual reality is to become an effective tool for the safety training of mine workers, its attributes will have to be measured against other forms of delivery. Accordingly, Carr (1992) listed the following areas in which VR should be considered the method of choice: ? When training mistakes would be costly. ? When the necessary environment cannot be experienced in the real world. ? To build interfaces that are sensible and can be manipulated. ? To make training situations really "real." ?To make perceptible the imperceptible.

Jan 1, 1997

By Egon Pohl, Peter Eckl, Friedrich Steinhäusler, Johanna Pohl-Rüling

RADON EXPOSURE AND CARCINOGENIC CELL TRANSFORMATION The highest radiation burden to miners is due to inhalation of radon and its short-lived decay products. The quantification of the risk associated with this radiation burden is complicated by modeldependent lung dosimetry, insufficient accuracy of past human exposure data as well as lacking knowledge about potential synergism of various carcinogens. Nevertheless, it is evident from epidemiological studies of miners that inhalation of elevated levels of radon daughters is correlated with increased lung cancer incidence (UNSCEAR, 1977). The situation is further complicated by the lack of reliable data on the biological variability of the latency period for the development of lung tumor under varying exposure conditions. At present information on variation with age is scarce, however, it is indicated that the excess lung cancer rate for workers exposed to high radon levels is considerably higher, if exposure occurs at ages over 40 years as compared to under 30 years of age (Sevc, Kunz, Placek, 1976). Furthermore, latency period is shorter by 6 - 7 years for smokers exposed to elevated radon levels than for non-smokers (Fry, 1976). Analysis of US- and CSR-uranium miner data revealed that the mean latency period is in the order of about 15 years (Jacobi, 1973). These uncertainties, together with medical diagnostic shortcomings, lead to the dissatisfying situation that at present the detection of radon induced injury of mining personal is primarily the assessment of the endpoint, i.e. radiation induced cancerous transformation of lung cells with typically less than 10% chance for recovery. Therefore it would be advantageous to develop practically applicable diagnostic aids to indicate already early precancerogenic changes of cell characteristics. This would permit the identification of specific population groups at increased risk for the development of lung cancer, thereby increasing the chances of more successful medical treatment. Despite continuous improvements in the reliability of test methods for the diagnosis of cancer cells there is still need for techniques, which enable the detection of transformed cells before the onset of invasion of the host organism. It is generally recognized that the transformation of a cell into a malignant state leads to a change of the cell surface, indicating a correlation between membrane-specific immunological properties and loss of growth control. Surface alterations on cells appear to be responsible in part for the malignant state and are not simply secondary effects of the transformation (Schnebli and Burger, 1973). Furthermore, membranes of cancer cells differ significantly from those of normal cells, particularly, in permeability properties (Rastogi, 1976). In dying cells, proteins, glycoproteins, peptides, aminoacids and their breakdown products are released, which block the permeation of the membrane itself. A mammalian cell can be considered as a 3-phase system (interior, boundary, environment) with the membrane forming a heterogeneous barrier between two subsystems. Under normal circumstances a difference of chemical potential is maintained on both sides of the membrane, causing an ion gradient across and fixed surface charges on the membrane. This results in a membrane resting potential (MRP) between cytoplasm and the bulk medium. It has been shown that MRP is a highly sensitive indicator for cellular reactions due to physical, chemical and biological agents, particularly whenever phenomena of transport and ion gradients as well as permeability are involved (Redmann, 1980). The primary interaction of the agent "ionizing radiation" with any form of living matter occurs at the cellular level. The component with the highest hit probability is the cell membrane. In the study presented MRP-changes of human cells were investigated with simultaneous measurements during irradiation and post-irradiation intervals up to six days. Furthermore, the suitability of MRP-measurements of human cells was tested as an indicator for early changes of cellular properties prior to the histological confirmation of carcinogenic transformation. EXPERIMENTAL METHODS Lung cells The biological specimen used were cultured human lung cells and human lung biopsy samples. Monolayers of lung fibroblasts (W138) were grown in petridishes using conventional culture techniques. In addition, transformed lung cells (W138SV13, subline 2RA) were used applying similar culture methods. All petridishes were incubated at 37°C and only cells in logarithmic growth phase were used. Freshly excised lung biopsy samples were obtained from randomly selected male and female patients (20 cases), where suspected or unclear malignancies were indicated by clinical or X-ray observations. At the time of sampling 80 % of the patients were or had been smokers in the past. The samples were taken by means of a stiff bronchoscope introduced into the trachea under local anasthesia with 1 % Novesinsolution (preparation with Atropin and Pantopen). This permitted the observation of both main bronchi down to the segmental bronchials. From each patient two tissue samples were excised from the mucusepithelial layer under visual control with fiber optics and transferred immediately into 1 % NaClsolution. One sample was taken from the suspected

Jan 1, 1981

This geometallurgical study examines the gangue mineral variability at the Bingham Canyon porphyry copper mine in Utah. Understanding an orebody?s mineralogy is important for mine and mill planning because it provides information on the size, texture, and distribution of ore minerals, the relationship between ore and gangue minerals, and the extent and type of alteration. Quantification of the mineralogical variability and properties of an orebody provides valuable input to the ore model and may have a significant effect on recovery optimization. This study was designed to be carried out on an initially detailed scale in order to develop a robust methodology for measuring and quantifying specific parameters, such as the distribution of mineral phases, alteration assemblages and fractures from key ore domains at the Bingham Canyon mine (Figure 1). Details of the methodology are reported below. This technique can be applied to testing the impact of mineralogy on a number of processing parameters. [ ] Figure 1. Ore domain map of Bingham Canyon (Kennecott Utah Copper, 2003) showing the 33 geometallurgical ore domains. The samples for this study were collected from the northwest part of the deposit circled on the map. PROJECT BACKGROUND Geology The Bingham Canyon deposit is a large porphyry Cu-Mo-Au deposit with associated skarn and base-metal replacement deposits mined in an open-pit mine measuring about 2.5 miles across and 4,000 feet deep. The deposit is hosted by the Bingham Stock, a Late Eocene to Mid-Oligocene intrusive complex. The skarn is hosted by the Late Carboniferous-age Bingham Mine Formation, which is comprised of quartzites and basal limestones (Babcock Jr. et al., 1998). The Bingham Stock is a composite intrusive complex that was emplaced over a period of about two million years. The oldest phase is described as a fine-grained equigranular monzonite (MZ), which intruded the country rocks at 39.8 ± 0.4 Ma (U-Pb zircon TIMS age) (Parry et al., 2001). Subsequently, the quartz monzonite porphyry (QMP) was emplaced, followed by intrusion of a latite porphyry (LP). The final intrusive phase, which forms narrow dikes that crosscut the Bingham Stock, is represented by a quartz latite porphyry (QLP), which is dated to 37.5 ± 0.4 Ma by 40Ar/39Ar dating of sanidine (Deino and Keith, 1998). Also present, are a minette dike in contact with a QLP dike (Waite et al., 1998; Deino and Keith, 1998), and a biotite porphyry (BP), a quartz latite porphyry breccia (QLPbx), and a pebble dike (Redmond, 2002). The copper orebody is centered above the Bingham Stock and forms an inverted cup shape with three high-grade copper zones extending to depth. Molybdenite mineralization occurs within and extends below the copper orebody, but is not correlated with copper mineralization. The main sulfide assemblage is chalcopyrite, bornite, molybdenite, and pyrite. Gold is locally intergrown with chalcopyrite and bornite (Babcock Jr. et al., 1998; Phillips et al., 1998). The surrounding country rocks host skarn deposits with three main ore types - garnet skarns, massive sulfides, and iron oxides. The garnet skarns contain chalcopyrite and pyrite with magnetite veins. In the massive sulfides chalcopyrite and pyrite occur either in banded sulfides or in unconsolidated microbreccias. The iron oxides contain disseminated chalcopyrite with minor chalcocite and bornite (Harrison and Reid, 1998). The deposit is overprinted by several stages of alteration. Potassic alteration is concentrated at the center of the deposit. It is surrounded and partially overlapped by a propylitic alteration zone. Both zones are overprinted by sericitic alteration. In the northern part of the deposit evidence for argillic alteration can be found (Bowman et al., 1987). Similarly, the skarn deposit was also overprinted by several stages of alteration: wollastonite, idocrase, and garnet in cherty limestones, and quartz and diopside forming in calcareous quartzites. Distally, diopside was replaced by talc, tremolite, dolomite, secondary calcite, and pyrite, and quartz and sulfide veinlets with biotite and actinolite selvages are present. Andradite garnet, diopside, quartz, magnetite, hematite, and copper sulfides were overprinted by wollastonite (Babcock Jr. et al., 1998). Because the monzonite, quartz monzonite porphyry, latite porphyry, and quartz latite porphyry host the bulk of the mineralization, our research is focused on these lithologic units. Geometallurgy On the basis of geological (lithology, alteration assemblages, fracture density, copper mineralization) and metallurgical properties, the deposit has been divided into 33 ore domains by mine geologists and metallurgists (Figure 1). In map view, these domains cross geologically defined boundaries (MZ, QMP etc.). These domains reflect regions of the deposit that have particular, mapable attributes or properties. They reflect a combination of geological and mineralogical characteristics that combine to impact processing. Alteration, for example, as shown by talc mineralization, is one such key feature. Hardness may reflect the absence of sericitic but presence of potassic alteration. Structural discontinuities such as faulting, fracturing, or development of void

Jan 1, 2009

By A. J. Richardson

Before the development of the underground stoping and mining costs can be considered, certain facts about the ore body, the proposed mine, markets, etc., must be known or determined. In the case to be studied, the zinc-lead mineralization occurred with a narrow vertically dipping structure of undetermined length and vertical extent. Exploration completed to date has revealed 6.5 mil¬lion st t of proven reserves. A further 820,000 st of in¬dicated reserves has been outlined and this tonnage is considered capable of being expanded by a factor of approximately four after more detailed drilling. After studying the market conditions and completing a very preliminary feasibility study, it was decided that production would be 730,000 stpy (or 2000 stpd) of ore. First year production would be at the rate of 1500 stpd. The main design criteria for the selection of the min¬ing methods are minimizing surface subsidence, maxi¬mum recovery of the ore body, maximum degree of grade control, maximum productivity, and safe working conditions. Two basic extraction systems are considered capable of meeting these requirements: mechanized cut¬and-fill stoping and sublevel long-hole stoping with filling. The primary development system of the mine has been designed to give maximum flexibility in stoping systems and layout and to permit changes if considered necessary as a consequence of actual production ex¬perience. At the present time, access to the mine is by a circu¬lar concrete lined vertical shaft, 16 ft diam, sunk to a depth of 1380 ft. Two exploration levels have been driven within the ore zone at depths of 165 and 1246 ft below the surface outcrop. The development to date had the objective of sampling the mineralization and produc¬ing detailed information on the outline of the ore body and the distribution and controls of zinc and lead values. In an attempt to satisfy the basic design criteria for the mine, it was decided that production would be best achieved by a combination of 40% sublevel long-hole stoping and 60% cut-and-fill mining. Costs of exploration and capital development of per¬manent underground facilities are normally written off over the life of a mine. Production expenditures, on the other hand, are of a temporary nature and are normally charged as and when incurred as an operating expense. Reasonably accurate predictions of mine production costs can be built up from engineering design and estimates of individual mine activities for ultimate inclusion in the comprehen¬sive data required for financial decision making. The simulated operations can be costed on a detailed basis in the form of a monthly operating budget. The budget format can be generalized or detailed, depending upon the scope of the project. However, ex¬perience suggests that a fairly detailed format has the advantage of assuring that all significant cost items are included. For underground costing it is suggested that the budget structure include five major cost centers (i.e. development, diamond drilling, ore extraction, hoisting/ transportation, and general mine expense). These in turn are detailed under numerous subheadings. The mechanism for compiling an operating budget will be illustrated. Because of its relative simplicity, ore extraction under sublevel long-hole stoping has been chosen for illustration. All other activities, simple or complex, can be estimated in similar fashion. BLOCK AND STOPE DEVELOPMENT Long-hole blocks, used where advantageous, will be up to 250 ft in height, depending upon the vertical con¬tinuity of the mineralization, and approximately 300 ft long. Drawpoints will be at 36-ft intervals and serviced by loading crosscuts driven from a footwall drift parallel to and close to the ore zone. Pillars between the stopes will be 50 ft wide. Stopes will be drilled off with vertical rings of blastholes drilled from sublevels approximately 60 ft apart vertically. This drilling will be done by percussion drilling machines (31/2 in.) mounted on a trackless drilling rig. Load¬haul-dump (LHD) equipment will be used to move broken ore from the drawpoints to the orepass connecting to rail haulage systems. On completion, long-hole stopes will be backfilled to prevent caving and to facili¬tate later pillar removal. From a planned stope layout, a forecast of produc¬tion and development is made in Table 1. Table 1. Block Tonnage and Stope Development Quantity Ore Waste Total ore block 375,000 st 2 stopes 310,000 st 1 pillar 65,000 st Access crosscuts, 4 at 100 ft 400 ft Drill sublevel drifts, 6 at 300 ft 1800 ft Stope raises, 3 at 250 ft 750 ft Undercut sublevel drifts, 2 at 300 ft 600 ft Loadout crosscuts at 35-ft intervals 550 ft 100 ft 3300 ft 500 ft Total development footage 3800 ft Tons per ft of development 987 st

Jan 1, 1982

By Paul M. Jr. Musgrove, Donald C. Moore

Conventional Smelting Practice Conventional copper smelting practice varies from smelter to smel¬ter, but generally consists of some or all of the following unit processes: roasting, smelting, converting, and fire refining. Roasting. Copper sulfide concentrates can be smelted directly or after an initial roasting step. Roasting is used in some smelters because roasting prior to smelting increases smelting capacity, less energy is required to melt hot roaster calcines than wet sulfide concen¬trates, roaster off gases are high in Sot concentration, 5-15% SO2, and some volatile impurities are removed from the concentrate prior to smelting. However, many smelters do not use roasters, because the problems associated with handling hot dry calcines outweigh the advantages mentioned. Concentrate roasting is performed in multiple hearth or fluid bed roasters. If the moisture is low, roasting can be performed autogenously, usually at 500-600°C. High roasting temperatures are avoided because excess oxidation of the iron compounds may lead to magnetite formation. Magnetite is detrimental to reverb operation because mag¬netite can combine with refractory minerals to form a highly viscous slag. This slag prohibits efficient matte-slag separation and leads to excessive copper losses. Also, magnetite can settle through the matte layer, deposit on the furnace bottom, and consequently reduce furnace capacity. Roasting is carried out only on sulfide concentrates prior to smelt¬ing in reverb or electric furnaces. For smelting processes, such as the flash and continuous that rely on the exothermic heat of oxidation of the sulfur minerals, roasting is not practiced. Reverberatory Smelting. The predominate copper smelting fur¬nace for the past 50 years has been the reverb. These furnaces are typically 100-120 ft long, 30-35 ft wide, and 12-15 ft high. A typical furnace layout is shown in Fig. 2. Refractory brick linings cover all internal surfaces of the furnace. Originally the flame was directed to reverberate or reflect off the furnace ceiling and melt the feed material. Current practice is to direct the flame down the furnace length to melt the concentrate. A method of charging the concentrates or calcines, generally along the side walls to minimize refractory erosion, is incorporated in the furnace design. The copper concentrates, calcines, and fluxes charged into the reverb undergo a series of complicated reactions as the temperature of the mixture increases. The reaction of the iron and copper sulfides with the oxygen in the furnace produces a molten Cu25-FeS mixture called matte. Copper smelting metallurgy is based on the fact that sulfur has a greater affinity for copper than for iron and most other common metals. Therefore, in a system containing copper, the copper will preferentially remain as a sulfide compound until all of the other metals have been oxidized. The oxidized metals combine with silica to form a silicate slag that floats on the matte and is removed from the system. Reverberatory furnace smelting chemistry can be approximated by the following chemical equations: FeS2 + O2 - FeS+ SO2 (1) The formation of FeS ensures that any copper present other than as sulfides will be reduced by the relationship: CuO2 + 2FeS + O2 - CuS + 2FeO+SO2 (2) or 2Cu +FeS - Cu2S + Fe (3) As the molten charge travels down the furnace, continued oxida¬tion of the iron minerals and sulfurization of the copper minerals occurs. When all of the copper has been converted to sulfides, the iron sulfides can then be further oxidized as: FeS + (3)2 O2 FeO + SiO2 (4) The FeO reacts with the silica added as flux in the furnace charge. A simplified equation is: FeO + SiO2 -FeO SiO2 (5) The iron silicate slag formed is skimmed from the surface at the end opposite the burners. The copper content of reverb slag is usually less than 0.6% Cu and is discarded. Matte is removed along the side wall and is taken to the converter for oxidation of the remaining sulfur and iron. The main objectives in reverberatory smelting are to produce a molten Cu2S-FeS matte containing 30-60% Cu and a throwaway slag. Production of matte permits complete conversion of all copper minerals into copper sulfides, which can migrate because of specific gravity differences, through the lighter slag layer. Also, the molten matte droplets collect the noble metals, gold and silver, as the matte settles in the furnace. The large settling area of the furnace provides enough separation time to produce a low grade slag, which can be discarded without further processing. High heat losses are associated with reverberatory smelting be¬cause of the large volume of gases sweeping through the furnace. Therefore, an outside source of heat is required to keep the smelting reaction going. Natural gas, fuel oil, or pulverized coal are used as this heat source.

Jan 1, 1985

By H. Lyn Bourne

This is the seventh annual tabulation of royalty information. It is also the first year in which some data have been deleted to make room for new data. The concept of royalties evolved from a time when the government owned all of the land, including mines, to the situation where free miners won the right to claim minerals but paid a portion of their production to the royal treasury. Today, a mineral royalty is a payment to the owner of the mineral rights for the privilege of producing the mineral commodity. However, some people incorrectly believe that the selling price and the royalty are the same thing. The contract between the owner (lessor) and the mining company (lessee) is the mineral lease. Some clauses that are common to mineral leases include: identification of property, granting clause, reservations, definitions, royalty rate, taxes and title, indemnity, termination, inspection, assignability, successors, and reclamation. There often are variations in royalty rates for a given commodity that reflect differences in location, quality, market conditions or public versus private ownership. History In the time of ancient Rome, the government owned the mining properties by virtue of conquest. It would lease the mines to favored citizens who would pay rent to the State. Various conditions of sovereign ownership of both land and mineral rights continued in Europe until the Renaissance. As the laws evolved for land ownership by private citizens, the concept that minerals belonged to the State (King, Crown, sovereign) continued until about the 15th century. Free miners challenged the notion of sovereign ownership and won the right to discover and claim minerals. But a portion of their production had to be paid to the sovereign - a royalty. So, the original concept of a mineral royalty was a tax on production that was due to the Crown or Church. The term mineral royalty, as it is known today, is a payment to the owner of the mineral rights (formerly the royal owner) for the privilege of mining and producing the mineral commodity. The owner of the mineral rights, the lessor, and the mine operator, the lessee, enter into an agreement to mine the property. The agreement is the lease. While this concept is common, there are some who do not understand that the royalty is a portion of production paid to the owner as agreed on in the lease document. This author has seen reports where the selling price of a commodity has been quoted as the royalty. ("They get 70 cents a ton royalty at their pit and the guy down the road only has a 65 cent royalty.") These reports have been authored by people not familiar with the mining industry. Lease clauses In addition to the amount to be paid the lessor, there are several other items to be addressed in the lease agreement. The following list may not be all inclusive, but briefly describes most of the common clauses any good mining lease should contain. Identification: This opening clause names the owner (lessor) and the operator (lessee), the address of each, and gives the legal description of the property. Granting clause: This part of the lease gives the time period or duration of the agreement and information about renewal periods. It also has language about the exclusive right of the lessee to mine the property. Reservations: If the owner wants to exclude any portion of the property or set some specific conditions about the operation, there needs to be a clause that describes these reservations. Definitions: This section should address some of the technical terms that the lessor may find confusing - short tons versus cubic yards, dollars versus percentage of average selling price, any escalator indices such as consumer price index or producer price index, and material mined versus material sold. Royalty: This section spells out what the royalty rate will be, how often it will be paid, if there is an annual minimum, the pay dates, and how the records will be kept. This section also describes the conditions under which the lessee is exempt from the annual minimum - natural disasters, strikes, governmental actions, or other causes referred to as force majeure. Taxes and title: The lease needs to identify who is responsible for the property taxes, severance taxes (if applicable), and other taxes that relate to the mining activity - taxes on equipment, improvements, or stockpiles. This is a good place in the lease for the owner to certify his ownership of the property and its mineral rights and also certify that no other leases are in effect. The lessees may want language that allows them to pay mortgages or other debts on the property to keep their lease in effect. Indemnity: This portion of the lease identifies that the lessee assumes the risks for lessee's mining operation. Lessor should expect indemnification by the lessee through standard insur¬ance policies - workers compensation, liability and property damage. Termination: Both the lessor and lessee want language that will allow them to terminate the lease. This section of the lease describes the conditions under which one of the parties may terminate the lease (failure of the

Jan 1, 1989

By M. G. Schulz

Mining of molybdenum at Questa, New Mexico has been accomplished by block cave methods since August, 1983. As caving progresses, a periodic geologic evaluation is made of the rock-types present in finger raises on the Grizzly Level of the mine. The production maturity of the cave can be monitored by relating this data to geologic cross-sections through the ore body. The draw point mapping program is a simple and effective tool that is used in making draw control decisions at Questa.

Jan 1, 1985

By B. F. Dickerson

STRATEGIC METALS! Recently, this money accented cry has been heard in such diverse locales as Mining company boardrooms, Banker's offices, Stockbroker's quarters, Swindler's dens and Congressional committee rooms. (In some cases, these locales are one and the same). Is the strategic metals rush for real? Should it be? Our paper attempts to give a very generalized view of the subject for a few metals, points to a few potential, but generally overlooked sources of these metals, and offers conclusions based on our studies.

Jan 1, 1981

By D. W. Jahn

Road construction in the near future will require contractors to guarantee that a project will remain trouble free for years after the project has been completed. These guarantees will challenge aggregate producers to become technically proficient in judging performance of their products. Testing procedures are described that may be used to predict performance of concrete and asphalt pavements before being committed into a construction project, and may also be used as quality assurance tools during construction to monitor performance as construction proceeds.

Jan 1, 1995

By H. E. Bonner

The recovery of fine coal has historically had limited success due to the intimate clay association on the surfaces of the coal particles. This clay presence has detrimentally affected conventional beneficiation techniques resulting in a recovered product containing unacceptably high concentrations of ash and moisture. An ultrasonically activated tray that operates in a continuous fashion has been developed that separates the clay film from each particle's surfaces. This separation is of sufficient duration to allow conventional beneficiation techniques to be utilized more efficiently.

Jan 1, 1989

By Robert M. Jimeson

The competitive market potential for solvent refined coal is estimated. Market advantages of solvent refined coal are enumerated. Markets are possible in combustion, railroad locomotion, and carbon electrodes. The combustion characteristics are consistent with expected air pollution restrictions on the emission of sulfur and particulate matter. A market potential of sufficient size exists to support the initiation of solvent refining in the United States. The market analysis should help fuel producers determine the advisability of their undertaking the solvent refining of coal.

Jan 1, 1969

By E. G. Loesche

Grinding mills in which the comminution takes place between rollers and the surface of a disc, table or ring are generally known as roller type mills. The Loesche Mill, also known as the Disc Roll Mill, is a special type of roller mill in which the grinding surfaces consist of two rollers assembled over a horizontal disc or table which rotates at a relatively low speed. This design is particularly applicable to industry's present day demand for large capacity grinding mills.

Jan 1, 1964

By J. Sanko

When faced with the task of designing a process control system the control engineer must consider the following: 1. The type of process to be controlled and the manner in which the process must be controlled (the algorithm). 2. The type of equipment to be used to implement the control system. 3. A means of describing the control system for use in the following areas: a. Project engineering. b. Procurement of the control system equipment. c. Plant startup. d. Operator training and reference.

Jan 1, 1981