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By D. Harris, M. Osterberg

This paper examines the economics of acquiring mineral exploration rights by royalty-rate bidding when the royalty basis does not provide for full cost recovery. Bidding takes place prior to exploration and the documentation of actual tonnage and grade. Consequently, it increases considerably the risk to exploration capital when the fraction of cost recovered is small and the product price exhibits large fluctuations. Price and grade risk are demonstrated on a 360-Mt (400-million-st) porphyry copper deposit by Monte Carlo simulation of discounted-cash-flow analysis. Copper price is modeled as a stochastic price process, and costs are based on US Bureau of Mines cost models. When both grade and price risk are considered, the probability for a negative NPV is 0.54, given a royalty rate of 5% applied to a basis that allows the recovery of costs up to 50% of product price. Investment risk could be considerably reduced by defining the royalty basis to allow greater cost recovery. Although such a basis would require society to share in the risk, society would benefit from greater resource development.

Jan 1, 2000

By Anthony G. Fonseca, W. W. Wen

About 45-50% of the coal mined in the U.S. passes through coal preparation plants; east of the Mississippi River this number increases to about 75-80%. Although the cost for coal preparation is worthwhile to some, the coal industry faces the challenges of continuing downward pressure on the price of coal and the impact of new environmental regulations. Coal preparation, as commercially practiced today, is an effective process achieving 75-803 ash reduction, 15-8m trace element reduction, and 85-90% Btu recovery; it is less effective for pyrite reduction (35-70%), and on-line operating time (40-60%), and suffers from obsolete control systems. Methods will be discussed for reducing costs of coal preparation and improving the performance of coal preparation plants. Comments are included on equipment selection, especially for -28 mesh coal, and prep plant operation and control practices. Btu recovery, ash and pyrite reduction, fines processing including dewatering and slurry fuel use options are emphasized. Trace element removal and expert control systems for maximization of prep plant operation also will be highlighted.

Jan 1, 1995

By F. L. Wilke

Underground mining is a very complicated and complex industrial activity. The uncertain and, in most cases, the incomplete knowledge of the geological and mineralogical nature of the deposits can cause unforeseen difficulties. For a safe and uninterrupted operation, in addition to good planning and scheduling, reliable and up-to-date monitoring and control of all processes and conditions become necessary. Today, this is even more important in view of increasingly difficult working conditions, poorer grades, and more complex and expensive machinery. In short, large capital investment and higher risk of financial losses are involved in modern-day mining operations. Monitoring and control of the underground mining process has become a very complex and difficult task in itself. Many different systems are available, and the correct choice .is of utmost importance from both the economic and safety points of view. This chapter will deal with aspects of underground production monitoring and control. There are, however, many other areas of equal importance which are covered in an excellent manner in a hand- book by Olaf (1976) on monitoring and control of underground operations.

Jan 1, 1979

By Kostas Fytas, Pierre Bousquet, Bill Evanelou

Acid mine drainage (AMD) is a serious environmental problem that preoccupies the Canadian Mining Industry. Considerable amounts of money are spent every year in an effort to prevent or reduce the acid mine drainage phenomenon. AMD occurs when sulphide minerals (ex. pyrite) contained in rock are exposed to air and water and subsequently oxidise to produce low pH water. This acid effluent has the potential to mobilise any heavy metals contained in the rock. Coating the sulphide minerals with silicates is a new promising technology to reduce AMD. Pynte is treated with a solution containing H2O2, sodium silicate and a buffering agent. H2O2 oxidises a small part of pyrite producing ferric iron (Fe3+) ions. These ions subsequently react with the silicate ions to produce ferric hydroxide-silica that precipitates on the pyrite surface producing a passive coating. This silicate coating can protect the grains of pyrite from oxidation. This paper presents a series of experiments that confirm that silicate coating can considerably reduce AMD.

Jan 1, 2000

By J. M. Stewart

The incidence of heat stroke in the South African gold mining industry is today small (less than 1 in 10 6 shifts worked). Acclimatization and selection procedures have been developed and applied throughout the industry, underground working conditions have, and are being improved, and personnel are to-day made more aware of heat stress and its consequences than ever before. Although these actions have, over the years, brought about a steady reduction in the incidence of heat stroke (see Figure 1) the small incidence of heat stroke which persists indicates that heat stress is still a problem. This realization provides the stimulus for the work presented in this paper, which has as its primary objective the development of reliable heat stress limits for men working in South African gold mines. [ ] In keeping with recent trends3I4 the approach followed in this paper is based on the physical principles of heat transfer. Detailed studies of heat transfer from humans have been undertaken,5-l1 and certain of the results form an important aspect of this Paper -

Jan 1, 1980

By M. Charles Gilbert

Basement rocks in southern Oklahoma are divided into two groups. One group is the Lower Cambrian Wichita Igneous Province, a diverse igneous suite that crops out in the western Arbuckle Mountains and in the Wichita Mountains. These largely bimodal igneous rocks were emplaced in an intracratonic-rift environment. The other group, the older, is a set of Precambrian rocks of the Eastern Arbuckle Province, yielding ages between 1,350 and 1,400 Ma, exposed in the core of the eastern Arbuckle Mountains. These are deeply eroded mesozonal granitic rocks and associated granitic gneisses cut by numerous dikes ranging in composition from diabase to rhyolite. The southern Oklahoma igneous rocks have long been utilized mostly as dimension and crushed stone. Most of the early quarries were in granite of various red hues for monuments and facing stones. Large crushed-stone quarries are now exploiting both granite and rhyolite, which is used chiefly as aggregate and railroad ballast. The exposed basement rocks in Oklahoma represent an underdeveloped and accessible resource.

Jan 1, 1999

In underground coal mining, one of the biggest challenges is spontaneous combustion, which will not only present safety hazards but result in reserve losses as a result of burnt coal. The released heat coupled with other combustible gases commonly encountered underground will significantly increase the risk of explosion. In this paper, three-phase foam as an environment-friendly fire fighting agent composed of nitrogen, water and fly ash is introduced. The nitrogen facilitates inertization of the fire zone; the water helps cool down the fire and the fly ash can closely cover the coal to isolate the oxygen. What's more, the fly ash and the foaming agent are good free radical absorption. The comprehensive merits mentioned above make three-phase foam quite effective in quenching spontaneous combustion. Experiments indicate that three-phase foam can significantly slow down the temperature rise of coal during oxidation. The comparison between slurry and three-phase foam shows that the latter one is capable of flowing upward in the porous media so as to extinguish the high-point fire and concealed fire.

Jan 1, 2011

By A. J. Benham, H. Kessler

In the UK a high proportion of land-won sand and gravel is extracted from sub-alluvial gravels and river terrace gravels located within river valleys. However, extraction from deposits of this type is increasingly proving to be less acceptable. Quarries within river valleys often have a high visual impact and the cumulative impact of these operations in close proximity to each other can be high (figure 1). River valley operations are almost always restored to open water. Whilst these may be attractive for nature conservation and provide leisure activities, they can also have a serious impact on the natural hydrology of the flood plain. Wet restoration of quarries located close to airports or airfields can also lead to concerns regarding increased risk of bird strike on aircraft. The Civil Aviation Authority recently suggested that an exclusion zone of 13 km be applied around all airports and airfields to reduce the potential for bird strikes on aircraft. This action is likely to have a serious impact on the availability of potential sand and gravel extraction sites in river valleys.

Jan 1, 2005

By A. Hoath, V. Paul, F. Haslam McKenzie

This paper considers mining ventures occurring in rural communities in Galicia, Spain and Western Australia, Australia. It compares and contrasts the communities where mining is taking precedence over other industries, examining the potential land use conflicts and the future of both the communities and the mines currently operating there. The Galician case study, Trevinca, is located 200 km inland and was once a primary producing area, notable for its scenic alpine landscapes, which have since been developed for small scale tourism purposes. The Australian case study, Boddington is located 100 km inland in what has been a highly productive farming area. Mining was a marginal industry in the case study areas but due to the comparative devaluing of agriculture and tourism and the increased value of mining outputs, mining has increased in scale and economic importance. This paper will consider the environmental, social and economic impacts that have occurred in both the case study localities. Where there have been land use conflicts, strategies for minimising the adverse outcomes will be considered.

Jan 1, 2011

By Richard E. Gray

Virtually all structures show some signs of distress due to deterioration of the building components, to changed loads, or to changed support conditions. Changed support conditions result from ground movements. In mining regions many cases of structural distress are attributed to mining without considering alternative causes. This is particularly true of coal mining since it occurs under extensive areas. Coal mining is estimated to have already undermined more than eight million acres and may eventually undermine 40 million acres in the United States (HRB Singer, Inc., 1977). Other nonmetal and metal underground mines impact much smaller areas. Although it is sometimes difficult, even with careful study, to identify the actual cause of damage, persons responsible for underground coal mining should at least be aware of possible causes of building stress other than mine subsidence. This paper presents information on distress to structures and briefly reviews a number of causes of ground movements other than subsidence: Mass movements, dissolution, erosion, frost action, shrinking and swelling, yield into excavations and compressibility

Jan 1, 1986

By B. Cavender

Mining managers trying to rapidly reduce production costs tend to implement a traditional set of top-down managerial practices: layoffs of employees, renegotiation of supplier contracts, cancellation of employee training, restrictions on travel, reductions in office supplies, and so forth. While these practices do reduce costs, the benefit is often limited in both magnitude and duration, and the workforce is usually left demoralized. Successful cost-cutters take a different approach. They make the continuous reduction of costs a priority for all members of the organization, whether managers or workers. The culture of these firms emphasizes the commitment, voluntarily given, of individuals and work groups to this goal. Cost cutting practices often reject all of the traditional methods mentioned above, but are far more numerous, innovative, and successful. This culture of cost reduction is the result of a set of leadership competencies that establish direction for the organization, align the organization’s various constituencies with this direction, and motivate and inspire the organization. Dramatic cost reduction then becomes a routine task rather than a heroic achievement.

Jan 1, 2000

By F. Vallianatos

The main objective of the present investigation is to demonstrate the potential of ERT (Electrical Resistivity Tomography) and HVSR (Horizontal to Vertical Spectral Ratio) methods as geophysical tools for the monitoring of subsurface cavities. The survey sites are located in Akrotirion Peninsula, almost 7 km east of Hania town in Crete Island, Greece. At this site, the surface expression of a known cavity with a diameter of about 25 m is visible. The true geometrical characteristics of the cavity were unknown since there are no boreholes in the area. The focus of this survey was primarily of a qualitative nature and the objective was to determine if ERT and HVSR could be used to identify and map near surface cavities (less than 30 meter in depth) in a limestones kartsic area such as Akrotirion Peninsula. A 2D/3D model of the resistivity distribution is given for the area under investigation. Furthermore, analysis of microtremors data provides a profile of the seismic response of the tectono-karstic voids.

Jan 1, 2006

By B. A. Osei

Research to evaluate possible metrics for predicting dredgeability of compact aggregates, by hydraulically actuated clamshell dredges, shows work done by the pistons as a viable metric. Analysis of field data shows that there is a low, positive, correlation between cycle time (CT) and work done. If this correlation exists, then CT has to be considered an independent variable affecting work done during dredgeability assessment. Further research is required to elucidate the relationship between CT and work done during dredging. The objective of this paper is to test the hypothesis that work done during dredging increases with increasing CT. Kinematics and dynamics of the hydraulic clamshell were modeled and implemented in Simulink® in MATLAB. The model was validated using field data. The model was then used to test the research hypothesis. The results show that work done increases with increasing CT. This work confirms that work done during dredging increases with increasing CT. This result indicates that though an operator can increase the CT to deal with difficult digging, inputting unduly high CTs results in higher energy consumption during dredging.

Jan 1, 2011

By C. Allen Born

There is a saying, the greater the gratitude, the shorter the speech. That puts me in a quandary, because while I am grateful for the honor you do me today, I also want to talk about a subject very important to all of us. A few months ago, when I was asked to submit a title for my talk, I chose "Quality where it counts." I did so because perhaps the most important thing we at Amax did in our restructuring was to commit to quality in all our businesses - quality people, assets, and operations. Together, they create quality performance, which produces quality growth and increased shareholder value - our prime corporate mission. We are dedicated to quality. At Amax, quality means everything. Today, I want to discuss quality in another context - the need for it in American education and what we have to do to achieve it. If we ignore this need, we will all suffer the consequences. And they will be upon us far sooner than the next century, barely a decade away. I think almost everyone in this room works for an organization that had to restructure in the 1980s. Mining companies that did not, just didn't make it. Well, we did. As an industry, we are seeing improved profits, positive cash flow, and a more competitive position in the world marketplace. But all the restructuring we have done, all the hard work, and all the pain that was part of it, will be in vain if, down the road, we do not have the educated people we need as workers. We need them to design, manufacture, and market the products that use the basic materials produced by the mining industry. Simply put, we are at a crisis point in education today. That is no new revelation. Nearly six years ago, the National Committee on Excellence in Education published its report, "A Nation At Risk." Since then, things have not gotten better. The Wall Street Journal, Business Week, US News & World Report, and Fortune have all recently published stories about the sorry state of education in the United States. The subject has become the topic of TV talk shows as well as national commissions, and for good reason. The pool of young people entering the US labor force is dwindling. In the next decade, 10 million fewer will enter the job market compared to the 1970s. But fewer of them will be qualified to do the jobs available to them. Here's why: • 20% of today's high school students drop out before they are 18 and another 20% graduate functionally illiterate; 40% of today's fourth graders think the world is flat; • 20% of today's sixth graders cannot locate the United States on a world map; • one of every three ninth graders cannot figure the change for a two-item meal - and I'm talking about a Big Mac and fries. These are not just problems of minority kids in big city ghettos. Fully 40% of all young working Americans cannot add up their lunch bill. Three out of every five college freshmen need some kind of remedial work. These statistics are frightening. Particularly so because, while the work force is becoming less qualified and our public education system is getting worse, our products and technologies are becoming more complex. We are approaching a time when we will have machines that recognize handwriting but people who cannot write. We will have technology to take voice commands, but people who do not know what they are talking about. The accelerating pace of technology is changing the nature of the job market. The fastest growing jobs now, and in the years ahead, are in professional, technical, and sales positions requiring the highest education and skill levels. Most of these jobs will require the use of a computer. Yet, 95% of today's graduating high school students have never laid a finger on a computer keyboard. While our education system is failing the students it is supposed to serve, other countries are doing far better. In a

Jan 1, 1990

By K. -A. Björkstedt

INTRODUCTION Strassa lies in the central part of Bergslagen, a tradi¬tional mining district, on the eastern side of the Stora Valley at an elevation of about 200 m above sea level. A railway siding runs between the mine and the Stora railway station from which there are railway connections to the shipping port and iron and steel works in Oxelosund, about 224 km away. The distance to the provin¬cial capital Orebro is about 60 km. The climate is typi¬cal for this part of central Sweden and is illustrated by the diagram of monthly precipitation and temperatures for the years 1968-1975 (Fig. 1). HISTORY There is no certain information as to when the Strassa mine was first worked, but it is known from sur¬viving accounts of mine inspectors that there were smelt¬ing works in operation in nearby villages in the 12th century. An example is the Gusselhytta ore smelting works, 10 km south of Strassa, which dates from this period. Around the year 1540 there were two smelting works in Strassa, the Upper Karberg and Lower Karberg works. Ore for these smelters was probably taken from Strassa and from the adjacent Blanka mine. In the year 1624 Strassa is mentioned by the painter Jons Nils Krook in an account of the iron mines in the Linde mining district (Linde Bergslags Jarngruvor). Several mines were listed in the area, the deepest being about 30 m. An impressive power installation is mentioned in 1639, including a piston system of lashed poles for transmit¬ting power from the Stora River to the Strassa fields. Its length was 2670 m. Common ground comprising about 20.2 km2 (5000 acres) of forest was allocated in 1689 for the furtherance of mining operations. Until the beginning of this century only the rich cen¬tral parts of the ore body were mined and these yielded, after handpicking, lump ore suitable for smelter feed. An example of the ore grades from these early times is an analysis of ore from the "Big Mine" (Storgruvan) from the year 1873: 48.5% Fe, 0.008% P, and 0.06% S. This same year a total of about 18 000 t was ex¬tracted from the Strassa mine. OWNERSHIP The mine was owned and run until 1874 by a min¬ing association made up of 119 so-called "bergsman," who were homesteaders often engaged in agriculture and timber-cutting as well. In that year the Strossa Grufvebolag (Mining Co.) was founded. In 1906 it was con¬verted into a joint stock company, the Strossa Gruveaktiebolag. This was acquired in 1907 by Metallurgiska AB for the implementation of Gustav Grondal's beneficiating and briquetting methods, for which the Strassa ore was well suited. The same year saw the completion of a new ore dressing plant with an annual production of 46 000 t of ore concentrate. In 1911 the mine passed to new hands, and in 1913 it was purchased by an Austrian company. Extensive new installations were made and in 1915 a new dressing and briquetting plant was completed with twice the capacity of the old one. In 1917 the Strassa mine was acquired by Granges. Be¬cause of unfavorable business trends and technical diffi¬culties, mining operations were brought to a close in 1923. Pumping kept the mine free of water until 1933 but it was completely filled ten years later. Up to 1950 the surface buildings and installations remained intact but the large dressing and briquetting plant burned to the ground in that year. Today only the machine shop re¬mains from this earlier period of operation, now housing parts of the Mineral Processing Laboratory. The decision to take up mining operations again was made in 1955 and construction work began the follow¬ing year. Of the old installation, only the "southern shaft" could be used for some development drifting after it had been completed with a new headframe. Other¬wise, all the buildings and installations required for the operations had to be rebuilt. New installations ready by 1960 were office and personnel facilities, a new shaft and headframe, a sorting and concentrating plant, a macadam plant, settling basins, pump stations, and a railway and yard with transport equipment. The instal¬lation was completed with two plants

Jan 1, 1982

By H. Wen

"Taking the long flame coal, gas-fat coal and anthracite as samples, we tested the adsorption quantity to single component gas of N2, CO2 and CH4 under atmospheric pressure phase at different temperatures. Then we analyzed the adsorption characteristics and models of different metamorphic coals. The results show that metamorphic grade, temperature and gases species are main factors to adsorption quantity of coal. The higher and lower metamorphic grade of coal have greatly influence on adsorption capacity while moderate grade of coal has opposite result. The coal adsorption amount to three single component gases under the same experimental condition is CO2> CH4> N2.The simulation precision order of four adsorption models is quadratic curve model > Freundlich isotherm model> Langmuir model >logarithmic curve model. Quadratic curve model and Freundlich isotherm model both can accurately describe the adsorption behaviors of N2 and CH4, different isothermal adsorption curve of CO2 needs two kinds or more models to describe. This has a reference value to the study of adsorption characteristics and models to single component gases.INTRODUCTION Adsorption is the interfacial phenomena that concentration of single or multiple components in the interface layer is different from the bulk phase (1964). Adsorption model is mathematical models to describe the adsorption characteristics of the adsorbent, mainly reflected to fitting effect of gas adsorption isotherm, which contribute to deeply understand the adsorption characteristics of adsorbent. Many scholars have carried out extensively experimental studies of the coal adsorption process from different angles. Zhao (2010) studied the influence of coal metamorphism to pore development of coal seam through a variety of experimental methods. Zhang (2006) analyzed the adsorption capacity and the controlling factors from three aspects of the coal rank, maceral and coal mass deformation. Cheng et al., (2002) studied the influence of pore size distribution of different rank coals to adsorption constants. Zhong (2002) carried out varieties of isothermal assay and established the prediction method of coal seam adsorption affected by a variety of conditions. R. M. Bustin (1998) proposed that we could not simply describe the change law of coal adsorption capacity and maceral content by a fixed parameter, and the adsorption capacity of the same coal rank also has great change. C. R. Clarkson et al., (1997) used four different adsorption models to describe the coal methane adsorption process, and the fitting precision of adsorption models is D-A equation >D-R equation > BET equation> Langmuir equation. Gasem, K et al., (2003) found that the fitted isothermal adsorption curve of D-A equation and BET equation are better than Langmuir equation under high pressure condition, while D-R equation and BET model are better to CO2 adsorption. In recent years, scholars’ at home and abroad research achievements of coal adsorption focused on high-pressure stage (about 0~15 MPa), mainly for coalbed methane exploitation, carbon dioxide trapping and sealing technology development, but the study of coal adsorption under atmospheric pressure phase is little. In this paper, we analyzed the adsorption characteristics and models under atmospheric pressure phase, it has a reference value to the study of characteristics and models to single component gas."

Jan 1, 2015

By P. Rosten

US mine production of iron ore in 1984 showed some improvements compared to 1983. But reduced demand from the iron and steel industry caused temporary shutdowns of many iron ore mines and pelletizing plants. US raw steel production in 1984 was slightly above 1983, but still at a depressed level. Production was 83 Mt (92 million st), compared with 77 Mt (85 million st) in 1983 and 68 Mt (75 million st) in 1982. Two major production trends continued in 1984. They were the increased production from electric furnaces and the growing use of continuous casters. Electric furnace production included 33.2% of the steel poured in 1984, compared with 31.5% in 1983. Continuous casting was used for 39% of 1984 steel production, compared with 32.1% in 1983. Statistical Process Control Statistical Process Control (SPC) has taken on new proportions in the iron ore and steelmaking industries within the last year. This mathematical technique is used to monitor, control, evaluate, and analyze a manufacturing process. The technique charts variability of important quality parameters. Training and adaptation of SPC techniaues for process control have been initiated at Inland, Steel's Minorca, Pickands-Mather's Hibtac, Cleveland-Cliff's Empire and Sherman operations, and at Reserve Mining. One of these operations has requested its bentonite supplier provide SPC charts on quality specifications. Some of the steelmaking operations (Inland Steel, Bethlehem Steel, Dofasco, LTV Steel, National Steel, Stelco, Weirton Steel, and Wheeling-Pittsburgh) have set up SPC programs within their operations. And they also have insisted that some of their suppliers use SPC. Plant Shutdowns The permanent closure of Stelco's Griffith mine at Red Lake, Ontario, has been delayed by one year. This gives employees more time to adjust. The mine is now set to close in April 1986, instead of April 1985. Sidbec (Canadian government) and its other partners (including British Steel Corp., Quebec Cartier Mining, and US Steel) closed its iron mining operations at Gagnon, Quebec. The pellet plant has been leased to Quebec Cartier. New Iron Ore Operations The massive Carajas iron ore project in Brazil is scheduled to come onstream in Jan. 1986. It is to achieve full-scale commercial shipments by July of that year. The 66% iron crude ore requires only crushing and screening before shipment. The product consists of 83% sinter feed and 17% coarse ore. Annual production capacity will be 32 Mt (35 million st) when the project is completed. Principal customer for the ore is Nippon Carajas Iron Ore Co., a consortium of Japanese steel mills. The Arab Iron & Steel Co. (AISCO) has started up a $US300 million, 3.6 Mt/a (4 million stpy) iron ore pelletizing plant built by Kobe Steel Ltd., at Al Hidd-hide in Bahrain. By 1986, this grate-kiln-cooler plant will supply high quality iron ore pellets to feed direct reduction plants in the immediate Gulf area and Far East markets. Iron ore supplied from Brazil, Peru, India, and Mauritania provides the feed to the pellet plant. Hydrated lime (2%) is used as a burden.

Jan 5, 1985

By William A. Griffith

The recent recession has severely impacted the performance and results of virtually all of our natural resource companies. The depressing climate continues to linger and recovery maybe sometime away. Problems remain for resource companies in the steel and petroleum industries as well as the mining business. In February, at the AIME Annual Meeting in New York, an All-Institute session presented a variety of views on the situation. A. T. Yu, chairman of ORBA Corp., Mountain Lakes, NJ, organized presentations by top management personnel of four natural resource companies. This well attended session heard management strategems for the present and views for the future. A compilation and synthesis of these presentations, gathered by Dr. Yu, are presented here for ME readers. Leading off will be William A. Griffith, president and chief executive officer of Hecla Mining Co., Wallace, ID. Other speakers presented here include Wilfred P. Schmoe, executive vice president of Du Pont Co., Wilmington, DE; Frank W. Luerssen, chairman and chief executive officer of Inland Steel Co., Chicago, IL; and Adam H. Zimmerman, president and chief operating officer of Noranda Mines Ltd., Toronto, Ontario. First, then Griffith's remarks. Introduction The key to successfully managing a natural resource company in austere times is good management in good times. In other words, position the company during prosperous times to survive the times when the well dries up. Although we know how to manage properly, for various reasons we sometimes do not do it. We forget the lessons of history. We allow ourselves to be carried away by our egos. We fail to position our companies properly in good times. As a result, in bad times we find ourselves in deep trouble. We need constant reeducation in the things we already know. In the natural resource industries, proper positioning in good times involves becoming a low-cost producer, retaining the flexibility to pull in our horns, developing a lean and effective organization, and maintaining a healthy balance sheet. Nothing improves the chance of survival during austere times as much as being able to produce at a lower cost than your competitors. In our business, that means having low-cost mines - low cost because the ore bodies are high grade or favorably located, and because they are efficiently operated. It also means recognizing the competition. The key numbers are the cost to produce an ounce of silver or gold. Nothing else really counts. And our competition is every other precious metal mine in the world. Flexibility is important when one gets stuck with a high-cost operation, often because things do not work out as we expect. It is important to be able to shut down an operation quickly and easily, without high holding costs, and without disrupting the corporate organization. A lean and mean, effective organization of competent people is vital during bad times. A company will not have that if it is not developed and maintained during good times. Finally, a natural resource company has to develop a healthy balance sheet during good times if it is to survive the bad. Money in the

Jan 6, 1985

By A. P. Cook

Methane drainage on a mine-wide scale is a relatively new technology to South African coal mines. Shallow seams and apparently low methane contents have been assumed to result in less methane problems than experienced in other countries. The introduction of deeper mines however, has now resulted in methane drainage taking on a higher priority. Methane contents in the region of 12 m3\t have resulted in one colliery introducing drainage as a ventilation support. Although a low seam permeability initially indicated reduced potential for drainage, early borehole flows of 90 m3\m\year have since increased to 450 m3\m\year. Rapid inflow of methane into goafs and sealed areas from seams surrounding the main production seam at another colliery have warranted extensive evaluation of the methane properties of these seams with the projected introduction of predrainage from surface. Methane pressures in excess of 1000 kPa and contents in the region of 10 m3\t again give methane volumes suitable for drainage. Coal seam drainage ahead of mining is becoming more significant and is likely to see an increase in the near future. INTRODUCTION Methane gas is an everpresent hazard associated with underground coal mining. Safe working levels of methane in the mine atmosphere are normally maintained by ventilation practises, ensuring sufficient dilution of the gas. However in some cases the ventilation must be assisted by methane drainage, either from the mined seam, or from adjacent seams and strata, or from goafed areas. South African collieries have practised only limited methane drainage until now. Relatively shallow mining depths, and apparently low in-seam methane contents have been assumed to result in fewer problems with methane than are the normal for other countries. This is now being shown to not necessarily be the situation. Work carried out by the Coal Mining division of COMRO (Cook and Erwee, 1991) indicates South African production coal seams have very similar methane retention properties to those of coals in other countries, with seam gas contents of up to 12 m3/t. This awareness, as well as greater mining depths, and higher degrees of mechanisation, has resulted in higher priority being given to methane emission problems throughout the industry. Increased levels of safety, as well as possible commercial applications, are the main reasons for the interest now being shown in methane drainage. Not only is there possible applications in the present production coalfields, but South Africa has vast areas of coal reserves which are presently non-mineable, now being seen as possible alternative energy sources. Limited methane drainage is practised within the industry, but only on collieries that have identified specific methane problems that can be alleviated by drainage. Historically this has been restricted to surface drainage of longwall goafs, reducing emissions onto the faces. More recently, horizontal in-seam holes have been drilled, until now for bord and pillar sections, but the results are being evaluated for later application to shortwall faces. Adjacent seams pose problems at some sites and vertical and cross measure boreholes are now being considered.

Jan 1, 1993

By Samuel A. Rasmussen

Lead anodes are used in commercial copper electrowinning operations, yet there is no method to calculate anode life. To be discussed in this paper are operating characteristics of rolled plate (Pb,Sn,Ca) alloy anodes at Morenci's electrowinning tankhouse along with fundamental operating conditions and how the anode reacts to these conditions. These include anode maintenance, electrolyte temperature and viscosity, cobalt concentration, and manganese concentration. Also to be discussed are anode substrate characteristics under normal operating conditions and how the corrosion rate is affected by changes in operating conditions.

Jan 1, 1995