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By J. Dasher

Regarding the March 1991 ME technical paper by De Souza and Moore: For more than a decade since my February 1981 article on how to use modern metric, which SME-AIME had decided to do, I have monthly pointed out metric errors to the editors. In part, I do this because there has been no action to al low editors to fix figures and tables or to allow them to require authors to do so. The latest resulting atrocity provokes this discussion of vibrating drill handle units being stated in decibels.

Jan 1, 1991

By J. Iannicelli

Kaolin tailings ponds play an important role in reclamation of land and water. Discharges impounded from kaolin plants include oversize fractions consisting of coarse kaolin, mica, quartz as well as magnetically extracted contaminents, acid filtrates, and plant washdown streams. Tailing ponds perform an essential function in sedimentation of particulates, blending and reoxygenation of liquid waste, and neutralization and clarification of discharge water. During the past fifteen years, most kaolin firms have segregated their coarse filler waste to allow for possible reclamation for production of delaminated coating clay. This excess coarse filler fraction constitutes a reserve for future coating clay production.

Jan 1, 1985

By Eric Leung, Stephen G. Hardcastle, Andrew Dasys

In today's economic environment, Canadian mines can ill afford to neglect their ventilation systems as they can consume 30- 40% of the electricity used in underground mines. In addition, Canadian mines can incur significant heating costs. For mines to be their most cost efficient they must embrace existing and emerging technology to optimize the use of their air; namely, maximizing its work in diluting and removing pollutants, limiting leakage, and avoiding the unnecessary consumption of costly fan pressure all the while ensuring the health of their workforce. Furthermore, in Canadian mines which are heavily dieselized there is great interest within the industry to convert from a rigid quantitative approach to ventilation, based upon engine size, towards a more flexible qualitative approach that provides credit for Clean engine technology" and permits ventilation supply to be driven and based upon pollutant demands. In the future, there is even the possibility that ventilation will only be required to supply oxygen to diesel equipment as the underground hands-on workforce is replaced by surface workers and tele-operation. Such changes will allow mine operators to minimize their electrical usage and operating costs, for in its simplest form the cost of running a fan is proportional to the quantity3; therefore, reducing current ventilation demands or limiting increases brought on by more stringent legislation, can produce very significant cost savings. CANMET, through ventilation surveys and use of its modern 3D-CANVENT ventilation simulator, have been demonstrating to the mining industry how ventilation can be optimally delivered at reduced costs. El-Equip with their leaky-feeder communications and MultiVENT monitoring and control system have facilitated mines to control fans and hence costs, and also monitor such ventilation parameters as pollutant concentrations. These two parties are now combining their efforts to develop an integrated air management system which will be demonstrated at CANMET's Experimental Mine Val D'Or, Quebec. With such an air management system, the ventilation engineer will have: 1) a simple to use simulator to design and test ventilation scenarios; 2) remote controls of fans, doors and regulators to implement changes; and 3) real-time monitoring of airflow, pollutant concentrations, and both vehicle identity and location to show whether changes are necessary. It is only when all three are available, that a mine's ventilation system can be operated at minimum cost.

Jan 1, 1997

Your thoughts on the current status of the global minerals industries? The global economic, technological, social and political changes of the last two decades of the 20th century resulted in the emergence of a restructured minerals industry. This industry is now based on a new cost-cutting philosophy; utilization of modern technology; productivity gains rather than production tonnages; diversification of mineral markets; and globalization of exploration, mining and processing. Quantity and tons used to be the focus. The emphasis today is on remaining competitive in the marketplace by lowering per-unit production costs as much as possible. What factors and trends will impact the minerals industries in this, the 21st century? A number of parameters will impact minerals operations and shape the future sustainability and growth of the minerals industries. Increased demand for minerals will be accompanied by the demand for technical advancements. We will also see a continued emphasis on health and safety, environmental stewardship, and education and training. Let me elaborate.

Jan 1, 2002

By Claude Deveau, Stephen R. Young

Introduction Tanco History Tanco is sometimes known as the Bernic Lake Mine. It is located about 180 km east-northeast of Winnipeg close to the Manitoba-Ontario boundary. Tanco operates an underground mine employing ramp access, room and pillar mining and shaft hoisting for the production of tantalum, lithium and cesium minerals. Tantalum recovery employs conventional gravity and centrifugal concentration methods along with a flotation process which recovers ultra-fine tantalum. All tantalum concentrates are shipped to Cabot Supermetals, Boyertown, Pa., for the production of tantalum chemicals and metals. Tanco also produces lithium products from spodumene ore. The lithium concentrates from Tanco are shipped worldwide for use in ceramics, specialty glass and mold powders. Cesium processing involves the dry grinding of pollucite as feed stock to the on-site chemical plant dedicated to the production of cesium formate, a high density drilling fluid. Tantalum milling operations commenced in 1969. In the early years of the operation, feed grades were three to four times as high as they are today. Coarse-grained tantalum mineralization with complete tantalum liberation at sizes of 300 µm allowed for easy recovery with conventional equipment such as spirals and shaking tables. Over the years, the process and feed material to the plant have drastically changed. Due to drastically reduced liberation sizes, efforts have been made to try to recover as much of the liberated particles as possible in order to maintain acceptable recoveries.

Jan 1, 2005

By T. W. Beck

Drilling into coal mine roof strata to install roof bolts has the potential to release substantial quantities of respirable dust. Due to the proximity of drill holes to the breathing zone of roof bolting personnel, dusts escaping the holes and avoiding capture by the dust collection system pose a potential respiratory health risk. Controls are available to complement the typical dry vacuum collection system and minimize harmful exposures during the initial phase of drilling. This paper examines the use of a bit sleeve in combination with a dust hog-type bit to improve dust extraction during the critical initial phase of drilling. A twisted-body drill bit is also evaluated to determine the quantity of dust liberated by comparison to the dust hog-type bit. Based on these laboratory tests, the bit sleeve may reduce dust emissions by one-half during the initial phase of drilling before the drill bit is fully enclosed by the drill hole. Because collaring is responsible for the largest dust liberations, overall dust emissions can also be substantially reduced. The use of a twisted-body bit has minimal improvement on dust capture compared to the commonly used dust hog-type bit.

Feb 27, 2013

By A. B. Holland-Batt

In the 1960s and 1970s, incremental development rather than innovation was the norm for gravity separation. However, the last 15 years have seen a number of new developments in this area. The article reviews the traditional gravity-separation techniques and then examines the newer developments such as centrifugal separators. Emphasis is placed on novel devices or improvements that offer better control or improved performance.

Jan 1, 1998

By D. D. Harbuck

Previous studies at the U.S. Bureau of Hines have shown that only 70 to 80% of the germanium in domestic zinc process residues can be extracted during H2S04 leaching. To increase germanium extraction, the Bureau developed and researched the hypothesis that minor amounts of germanium and zinc silicate, both present in zinc calcine, dissolve during the leaching stages of zinc processing, forming soluble germanium and silica gel. This silica gel then selectively adsorbs germanium from solution, rendering the germanium insoluble. Testing showed that as the amount of silica gel formed increased, the amount of insoluble germanium in the zinc residue increased. Several processing alternatives are presented for overcoming this problem.

Jan 1, 1991

By Z. Yu

Dewatering of a -0.5 mm fine coal has been studied extensively. Deep cleaning requires however fine grinding, and dewatering of such ultrafine products presents a great challenge. Several coal samples finely ground and characterized by different wettabilities have b.een used in the filtration tests. Vacuum and press filters have been employed. In this paper only the results obtained with different flocculants (totally hydrophobic. semi-hydrophobic and hydrophilic polymers) are included. The results reveal the effect of coal surface properties and flocculant type on filtration of ultrafine coal.

Jan 1, 1994

By Richard L. Bullock, Bruce Kennedy

Vince Lombardi once said, "Practice doesn't make perfect, perfect practice makes perfect." When it comes to building a mine that will operate at the optimum level for the set of geologic conditions from which it was developed, Lombardi's remark might be paraphrased to describe the problem: planning won't guarantee the best possible mine operation unless it is the best possible mine planning. Any sacrifice in the best possible mine planning introduces the risk that the end results may not reach the optimum mine operation desired. This section addresses many of the factors to be considered in the initial phase of mine planning. These factors have the determining influence on the mining method, the size of the operation, the size of the mine openings, the mine productivity, the mine cost, and, eventually, the economic parameters used to determine whether or not the mineral reserve even should be developed. A little-known fact, even within the metal-mining community, is that room-and-pillar mining accounts for most of the underground mining in the united States. According to a 1973 study on noncoal mining (Anon., 1974), more than 76% of the producing mines [of over 1089 t/d (1200 stpd) capacity] produced approximately 70 000 000 t (77,000,000 st) or 60% of the nation's underground tonnage of material by room-and-pillar mining. That same year, 96.8% of the nation's under- ground coal mines produced 262 950 000 t (289,911,000 st) of coal extracted from room-and-pillar mines (Anon., 1976). Thus, nearly 333 000 000 t (367,000,000 st) of the United States' raw material is produced from mines using some form of the room-and-pillar mining system. Because approximately 90% of all mining in the United States is done by some variation of room-and- pillar mining, it is appropriate to give special emphasis to the effects of the various elements of mine planning on room-and-pillar mining. The relationship of these elements to other mining methods will become apparent as the elements are described in later sections herein. TECHNICAL INFORMATION NEEDED FOR PRELIMINARY MINE PLANNING Assuming that the reserve to be mined has been delineated with diamond-drill holes, the items listed in the following paragraphs need to be established with respect to mine planning for the mineralized material. Geologic and Mineralogic Information The geologic and mineralogic information needed includes the following: 1) The size (length, width, and thickness) of the areas to be mined within the overall area to be considered, including multiple areas, zones, or seams. 2) The dip or plunge of each mineralized zone, area, or seam, noting the maximum depth to be mined. 3) The continuity or discontinuity within each of the mineralized zones. 4) Any swelling or narrowing of each mineralized zone. 5) The sharpness between the grades of mineralized zones within the material considered economically minable. 6) The sharpness between the ore and waste cutoff, including whether this cutoff can be determined by observation or must be determined by assay or some special tool; whether this cutoff also serves as a natural parting resulting in little or no dilution, or whether the break between ore and waste must be induced entirely by the mining method; and whether or not the mineralized zone beyond (above or below) the existing cutoff represents submarginal economic value that may be- come economical at a later time. *7) The distribution of various valuable minerals making up each of the minable areas. 8) The distribution of the various deleterious minerals that may be harmful in processing the valuable mineral. 9) Whether or not the identified valuable minerals are interlocked with other fine-grained mineral or waste material. 10) The presence of alteration zones in both the mineralized and the waste zones. Structural Information (Physical and Chemical) The needed structural information includes the following: * 1 ) The depth of cover. 2) A detailed description of the cover including: the type of cover; * the structural features in relation to the mineralized zone; * the structural features in relation to the proposed mine development; and * the presence of and information about water, gas, or oil that may be encountered. 3) The structure of the host rock (back, floor, hanging wall, footwall, etc.), including: * the type of rock; * the approximate strength or range of strengths; * any noted weakening structures; * any noted zones of inherent high stress; noted zones of alteration; the porosity and permeability; * the presence of any swelling- clay or shale interbedding; the rock quality designation (RQD) throughout the various zones in and around all of the mineralized area to be mined out; the temperature of the zones proposed for mining; and the acid generating nature of the host rock. 4) The structure of the mineralized material, including all of the factors in item 3 plus: * the tendency of the mineral to change character after being broken, i.e., oxidizing, degenerating to all fines, recompacting into a solid mass, becoming fluid, etc.; * the siliceous content of the ore; the fibrous content of the ore; and the acid generating nature of the ore. Economic Information The needed economic information includes: *1) The tons of the mineral reserve at various

Jan 1, 1982

By R. Barthel, O. Nitzsche, J. Pateiro Fernández, T. Cramer

The Hong Gai coal field in northeast Vietnam has been the main coal mining area of Vietnam for more than 150 years. Anthracite coal is produced from several open pit and underground mines situated close to the UNESCO world natural heritage site Ha Long Bay. The mining-induced environmental impacts such as dust emissions, acid mine drainage, and visual impairments due to waste dumps resulted in severe conflicts of interests regarding future land use and the protection of the world natural heritage site Ha Long Bay. Within the RAME project (Research Association Mining and Environment in Vietnam), Brenk Systemplanung is contributing to an improved environmental and sustainable planning in Vietnam's mining industry and the reduction of environmental impacts on Ha Long Bay by developing suitable and sustainable technology and planning measures (e.g. for dump construction/rehabilitation, predictive modelling, and/or monitoring) for Vietnam's leading coal producer.

Jan 1, 2011

By Dominc C. Torre

INTRODUCTION Rapidly increasing capacities of equipment used to load and handle material at the face require improved haulage equipment and better methods of transporting the mined materials or "muck" to the shaft or slope and out of the mine to the processing plant on the surface. Increasingly, those transportation demands are being satisfied with underground belt conveyors. Such con¬veyors provide the most readily available, most efficient, and most reliable method of carrying materials in a continuous and rapid flow from the face loading equip¬ment to the surface plant. Almost universally, belt con¬veyors are used in coal mines and those nonmetallic and metallic mines operating in relatively flat bedded deposits. Belt conveyors are available in a wide range of capacities, mainly limited by belt width, belt speed, and weight of the material to be transported. They can be used on the level, on grades, on the surface, or under¬ground. They provide a rapid and constant flow of material, transporting the material as quickly as it is mined. Length of belt conveyors is almost unlimited. Where the haulage distance exceeds the practical capacity of a single conveyor unit, two or more conveyors can be used in series. Single conveyors more than 1.6 km (1.0 mile) long are common; multiple-unit conveyors in series operation are transporting materials over distances exceeding 16.1 km (10 miles). Depending upon mate¬rials being transported, job conditions, cost of the terrain being spanned, and alternative haulage methods avail¬able, conveyors can be conceivably economical for even greater distances. Table 1 lists maximum belt speeds recommended for most materials, relating belt speeds to belt widths. Table 2 lists capacities of typical conveyors of various widths and speeds, transporting commonly mined mate¬rials of various weights. ADVANTAGES OF CONVEYOR SYSTEMS For several years after their initial introduction, belt conveyors were available only with rigid side frames or a supporting structure of steel and concrete. That con¬struction limited underground applications, due to the cost and relative inconvenience of extending or retract¬ing the belt conveyor in the confined underground environment. However, during the last 20 years, wire-¬rope side-frame belt conveyors, as shown in Fig. 1, have become widely used in underground applications. Even wider use can be anticipated with their application to the fast movement of materials in surface mining operations. Advantages of the wire-rope side-frame belt con¬veyors were realized first in panel or section belt haulage in coal mines. Soon afterward, use of those conveyors was extended to gathering and main-line haulage. The mobility of the wire-rope side-frame conveyor is the principal reason for its success. The conveyor can be extended, retracted, dismantled, moved, and reassembled easily, even in relatively confined under¬ground spaces. The intermediate structure consists of rope support stands, wire-rope side frames, wire-rope tie-off stands, and the necessary carrying idlers and return idlers. An important and very attractive feature is the ability to suspend the conveyor from the roof in an underground mine, as shown in Fig. 2, leaving more room for improved housekeeping and allowing passage of face-service equipment, haulage vehicles, and other mining equipment. The conveyor's open construction allows quick and easy visual inspection of its com¬ponents for failures or malfunctions; it also facilitates checking and correcting conveyor-belt alignment. Other advantages contributing to the attractiveness and widespread application of wire-rope side-frame conveyors in main-line, slope, and surface installations include: lower capital costs, lower installation costs, lower maintenance costs, reduced impact on idlers and belting, reduced spillage and minimal cleanup, improved conformation to undulating terrain or mine bottoms, and the ability to span most obstacles without heavy structural support. CONVEYOR CLASSIFICATIONS Underground belt conveyors are classified normally according to their function. Generally, conveyors are classified into one of four main categories: 1) Panel or section conveyors normally receive the material to be transported directly from the face-haulage equipment. 2) Gathering conveyors are secondary haulage units that usually receive material from two or more panel conveyors. 3) Main-line conveyors transport all the material mined in the underground operations to the slope or shaft. Normally, they receive the material from two or more gathering conveyors. 4) Slope conveyors generally operate in tandem with the main-line conveyor, providing continuous Table 1. Maximum Belt Speeds Recommended for General Use Run-of-Mine Hard Ores and Belt Width, Coal and Earth, Primary Crushed mm (in.) m/s (fpm) Stone, m/s (fpm) 356(14) 1.52 (300) 1.52 (300) 406(16) 1.52 (300) 1.52 (300) 457(18) 2.03 (400) 1.78 (350) 508(20) 2.03 (400) 1.78 (350) 610(24) 2.54 (500) 2.29 (450) 660(26) 2.54 (500) 2.29 (450) 762(30) 3.05 (600) 2.79 (550) 914(36) 3.30 (650) 3.05 (600) 1067 (42) 3.56 (700) 3.05 (600) 1219 (48) 3.56 (700) 3.30 (650) 1372 (54) 3.56 (700) 3.30 (650) 1524 (60) 3.56 (700) 3.30 (650) 1676 (66) 4.06 (800) 3.81 (750) 1829 (72) 4.06 (800) 3.

Jan 1, 1982

By E. Allen Wendt

It is both a great pleasure and something of a challenge for me to have this opportunity to address a gathering encompassing such a wealth of expertise in the minerals field, It is particularly challenging because I have been asked to turn your attention from the relatively glamorous subjects of gold and money to the more mundane questions of our International commodity policy and the place of buffer stocks in that policy. However, these questions may be of more immediate importance for our economic interests at home and Abroad. I can testify that the problems affecting international commodity markets and the possibility of international action To resolve those problems are matters of real concern to Washington as well as to your industries,

Jan 1, 1978

By W. Burr Bennett

The prestressed concrete industry in particular, and the precast concrete industry to some extent, are rank newcomers to the concrete construction field compared to the cement, ready-mixed or concrete masonry industries. This young industry reflects its youth and vigor in its enthusiasm, optimism and the belief that it can reach any goal it chooses to set -- and it is setting its sights high. The prestressed and precast concrete industry fully expects to become the major structural and architectural material by the 1980's. Before exploring how the industry expects to reach this goal, a brief look at the origins and the growth of the industry may be useful in an evaluation of the feasibility of this goal. It was always recognized that concrete, strong and efficient for supporting loads which cause compression, was weak and inefficient when used to carry loads which induce tension. Thus the reason for reinforced concrete in which the concrete efficiently carries the compression in a flexural member while low grade steel bars reinforce the concrete in the areas 'of tensile stress. (Fig. 1). The steel being relatively inexpensive, can passively, but quite effectively carry tensile force while the concrete carries compression. The concrete in contact with the reinforcing also protects the steel from corrosion and acts as insulation to provide a superior "built-in" fire resistance. The major disadvantage of reinforced concrete relative to its main competitor, steel, is its weight in relation to its load-carrying capacity. Reinforced concrete systems, such as waffle slabs, I-beams, thin shells, etc. ,

Jan 1, 1971

By H. Akbari

Ordinary portland cement (OPC) is the key pozzalonic component of the concrete mix widely used as a construction material worldwide. B illions of tons of OPC are used in the construction industry each year. However, calcinations of limestone and silica that produce OPC also produce almost an equal amount of C O2 during the cement manufacturing process. Thus, OPC production accounts for nearly 7% of all anthropogenic C O2 emissions each year. The main objective of this study was to develop a geopolymer-based composite to be used as a substitute for OPC in concrete application to significantly lower the carbon footprint of the construction industry. A waste material produced during the coal combustion process was used as the main raw material for the geopolymer-based composite. It was mostly the nonmetallic content of the F-type fly ash produced from the combustion of bituminous coal. The authors envisioned extracting some of the valuable metal oxides from fly ash prior to using the major nonmetallic portion of the fly ash for geopolymer concrete application. The results obtained from this study showed that the compressive strength of geopolymer concrete compares favorably with that of conventional concrete prepared using OPC.

Dec 1, 2013

By C. H. Bucknam

Metallurgical processing of gold ores in positive water balance environments has been facing decreasing discharge concentrations in permits and additional requirements to pass acute toxicity testing before discharges will be allowed to native fisheries. In response to the challenge to meet 0.005 mg/L free cyanide guidance for discharges to fresh water fisheries, the American Society of Testing and Materials (ASTM) International Cyanide Task Group has undertaken an interlaboratory study for the free cyanide method in the metallurgical processing cyanide detoxified reverse osmosis effluent to determine if the quantitation limit for the method could be lowered from the current 0.009 mg/L free cyanide (1) to less than the 0.005 mg/L guidance concentration. Results of the testing are presented below.

Jan 1, 2012

By E. W. Lindroos, Fred D. DeVaney, R. L. Bennett, R. W. Hernlund, W. R. van Slyke, W. F. McDermott, C. U. Keranen

INTRODUCTION Iron is the world's most widely used metal and constitutes about 5% of the earth's crust. Iron ores are found widely distributed throughout the world. Because of its wide occurrence and relatively low value, an iron ore to be merchantable must contain a relatively high percentage of the metal to be considered as a source of iron. Few ores containing less than 25% iron would be considered as ore unless they existed in large amounts and could be concentrated very cheaply. The grade of the ore, the ease of concentration, and the transportation cost to market are fundamental considerations deter- mining its worth. Iron never occurs as a natural metal except in meteorites. Most iron ores occur as oxides, and to a lesser degree as carbonates. A small amount is recovered as a byproduct from iron sulfides. Iron ore must be reduced (oxygen removed) to metal for use. Iron is marketed in many forms and combinations, such as pig iron and a great variety of steels. Iron is practically never pure as marketed but contains varying amounts of carbon, phosphorus, sulfur, and alloying elements such as nickel, chromium, etc., all of which affect the physical proper- ties of the end product. Please note that in this section all analyses ore on a dry basis and all tonnage figures are on a long-ton basis of 2,240 lb unless otherwise noted.

Jan 1, 1985

By H. C. Juvkam-Wold

The design of an aquifer depressurization system is discussed. The system uses a number of wells surrounding a mine shaft to reduce the aquifer pressure in the vicinity of the shaft. The effect of various parameters such as number of wells, wellbore diameter, time and well location is discussed. It is concluded that, with a properly designed depressurization system, the aquifer pressure and the water inflow rate to the shaft may be reduced to less than 15X of their potential values in the absence of wells

Jan 1, 1980

By G. Raspa

This article describes a procedure for calculating the recoverable reserves of stratified orebodies characterised by a thin and irregular layers. An application on the phosphate deposits in the N'Zeto region of the Popular Republic of Angola is also described. The procedure consists in building a block model of the deposit through the conditioned multivarial geostatistical simulation of small areal units. The recoverable reserves are then calculated and defined by applying to the model a selection processes based on measured geological/economic parameters taken from the drillholes: thickness of overburden and mineralised layers, economic grain-size fraction, grade. The procedure also takes account both of the geometrical constraints of the mining method and dilution. For reasons of confidentiality, a multiplier has been applied to the values adopted for the sampling data.

Jan 1, 1992

By W. G. Willson, D. E. Walsh, B. Irwin

Low-rank coal (LRC) drying processes are generally categorized by operating temperature, drying environment and type of feed (either sized or ground coal). Within these broad categories, drying processes differ according to the type of drying equipment and methods of quenching and stabilizing the dried products. This paper focuses on the produce quality of various LRC drying processes including conventional low and high temperature evaporative drying and non-evaporative, hydrothermal drying. The former may be preferred if the dried product can be utilized immediately, but moisture reabsorption, spontaneous heating and fines production during handling are problems associated with longer term storage, transportation and utilization. Methods for reducing these problems are discussed. Hydrothermal processing is an advanced technology featuring high pressure, non-evaporative drying, which solves stability problems by producing a liquid feel.

Feb 24, 1997