Search Documents

By Estanislao Dunin

Aunque el Perú disponga de un potencial carbonífero suficiente, no ha logrado posicionarse como principal productor de carbón. Dicha crisis es atribuida al fracaso gubernamental en el manejo de difusión y gestión del carbón peruano. Por ello, el presente texto analiza este problema a través de la tenencia de yacimientos de carbón, entidades nacionales relacionadas con el carbón y así buscar un adecuado fomento de la minería en el carbón.

Nov 1, 1982

By Richard R. Klimpel

The first part of this two-part article summarizes the result of a 10-year, multimillion dollar research and plant testing program involving operating mining companies throughout the world. The program was aimed at developing a better understanding of the influence of slurry rheology on the performance of mineral/coal grinding circuits. Part 1 presents the basic concepts identified, including typical laboratory results showing the influence on grinding behavior of controlled changes in percent solids, particle size, slurry temperature, and viscosity control chemicals. Part 2, in January, will illustrate typical industrial scale test results on both open and closed circuits using the concepts presented in Part 1. Special emphasis will be placed on identifying some industrial operating implications of controlling rheology by different methods. Introduction The industrial-scale practice of wet grinding minerals and coals in tumbling media mills (ball, rod, and pebble) is well-known to operating mineral processing engineers and plant design personnel. Over the last century, considerable experience and data has been collected, correlated, and put into rules or guidelines for successful circuit design and operation. Typical factors influencing circuit throughput that have been analyzed in some depth are mill diameter and length, grinding media size and loading, feed and product particle size, mill power use, and the interaction of classifier type and efficiency with the grinding device. Until recently, knowledge of slurry rheology influence on large scale grinding circuit performance has been limited. Even today slurry rheology effects are essentially ignored in plant design. Indeed, in most plant operations only qualitative guidelines are followed. For example, too thick a slurry causes throughput losses and too thin a slurry uses excessive water or causes water handling problems such as pumping limitations. A search of published literature and numerous discussions with experienced plant operating personnel has shown an awareness that changing the percent of solids in the mill influences grinding or the response of grinding involving fine feeds versus coarse feeds. However, most the work identified relative to rheology effects in mineral/coal grinding was qualitative. Even in the few studies that were more quantitative, the scope of the work was usually too narrow to draw general conclusions. Also, the detailed rheological characterization tied to observed breakage and the combination of laboratory to industrial-scale testing that is required to develop a broad understanding of any factor influencing grinding had not been done. In this environment, this detailed program began in 1967. It had three distinct goals: • To develop a basic understanding of slurry rheology influence on breakage characteristics in the laboratory. • To test general rheology concepts developed in the lab on the industrial scale. • To develop a commercially viable chemical approach to controlling slurry rheology that would lead to the use of chemical grinding additives or grinding aids. The goals have been met, at least in part, this year. A small fraction of the extensive laboratory and plant results have been made available in published literature. Much of the research program dealt with identifying and developing chemical grinding aids, but a lot of useful and practical information on percent solids, particle size, and slurry temperature influence on grinding circuit performance also was collected. The purpose of this article is to present a clear and concise sum¬mary of the results of the entire program. The importance of rhe¬ology control in grinding circuit behavior will be demonstrated using a series of carefully per¬formed industrial scale experi¬ments (both open and closed cir¬cuits) that have not yet been reported in general literature. Mining companies participating in the test program on a proprie¬tary basis have found the informa¬tion in this article to be useful in better understanding and improv¬ing circuit performance. Viscosity Effects in Grinding Studies In this program&apos;s previous labo¬ratory studies, it was shown that there is a consistent pattern of change in specific rates of break¬age of both mineral and coal slur¬ries as slurry fluidity changes. Using the net production rate of material smaller than some spec¬ified size-for example, kg/hr of <75 µm (200 mesh)-as an index of mill production in a standard batch mill test (with a given feed material, feed size, mill, and mill conditions such as constant time of grind), the following facts were established (see Fig. 1): • The normal range of low den¬sity, low viscosity slurry (region A) gave no variation in mill produc¬tion. The measured rates of break¬age exhibited normal first order grinding. • Grinding of a somewhat higher viscosity slurry (region B) could give increased production. The higher viscosity was obtained

Oct 12, 1982

By W. L. Wearly

El presente texto decribe el proceso de mecanización en la minería donde hay reducción del costo de mano de obra. Para elllo, se revisa la historia de este proceso desde el siglo XIX hasta la actualidadd (1970).

Sep 1, 1982

By Enrique Cervantes

Durante mucho tiempo, las vetas angostas generaron inquietud para los operadores mineros - en tanto su morfología provoca una baja productividad, así como el aspecto técnico obliga a depurar sus sistemas. En ese sentido, el presente texto refiere el método de corte y relleno como el más adecuado para la explotación de vetas puesto que puede adaptarse a las características de este tipo de yacimientos, además del alto grado de flexibilidad para adoptar algún cambio de sistema.

Sep 1, 1982

By Julio Auzmendi

Dado que algunas industrias utilizan material a granel en sus procesos, este puede presentarse en fábrica, envasado, en sacos a granel, camión cisterna o volquete. Sin embargo, se generan problemas de diversa índole Por lo que el presente texto describe los posibles problemas encontrados cuando las industrias utilizan este tipo de materiales como: problema de recepción, almacenamiento y extracción, transporte a la zona de preparación o mezclado, dosificación y transporte a las máquinas del proceso y transporte del material elaborado a los puntos de consumo, así como las soluciones.

Sep 1, 1982

By Patricio Campos

Durante los diez últimos años, la perforación hidráulica ha desplazado al sistema neumático en aplicaciones mineras y obras civiles. En ese sentido, el presente texto describe las ventajas e inconvenientes de este sistema hidráulico como alternativa futura en el campo de la perforación. La aplicación de esta tecnología aumentó la productividad en la perforación de roca y disminuyó a un costo menor de operación que la de perforadora neumática. De forma que se la considerará como proceso obligatorio en breve plazo, al tiempo que mejora el ambiente de trabajo del personal.

May 1, 1982

By Richard J. Mainiero

The Bureau of Mines has developed a prototype nonincendive explosive rock-breaker charge that can be fired unconfined in underground bituminous coal mines without the danger of igniting a flammable atmosphere that might be present. At present, unconfined shooting in underground coal mines is prohibited, but there are situations where the use of such shots would yield an overall improvement in safety. The charge consists of l-1/2 lb of permissible water gel explosive in the form of a short cylinder 7 inches in diameter and 7/8 inches high, surrounded by a l/2-inch-thick layer of damp salt, and encased in latex rubber reinforced with cheese cloth. The latex rubber housing provides a charge package that is strong enough to resist rough handling yet is pliable enough to conform to an irregular stone surface. A charge of this shape was found to be more effective at breaking rock than charges with lined or unlined cavities. Incendivity tests in a gallery have shown that the prototype charge will not ignite a flammable methane-air atmosphere when fired. Rock- breaking tests made with limestone boulders indicate that the charge will satisfactorily break stone slabs weighing 1 to 2 tons, and that two or more charges might be effective for slabs weighing up to 10 tons. In cooperation with the Mine Safety and Health Administration (MSHA), a test protocol for the certification of these charges as "permissible" for use in flammable atmospheres is being developed.

Apr 1, 1982

By Mario Samamé Boggio

El presente texto describe algunos aspectos de la inversión extranjera en tres períodos: fines del siglo XIX, la primera mitad del siglo XX y segunda mitad del siglo XX. Dentro de lo quince casos analizados se halló que 5 empresas son iguales: Northern, Southem, Santander, Santa Luisa y Madrigal; 4 empresas se han "peruanizado" total o parcialmente: Caylloma, Ticapampa (Alianza), Lampa (Minsur) y Ruaron, 3 empresas se han agotado aparentemente: Santo Domingo, Salinas y Minas Ragra, 1 yacimiento revertió al Estado y fue desarrollado por Minero Perú: Cerro Verde; y 2 empresas fueron expropiadas y estatizadas: Cerro de Pasco Corporation y Marcona. En todos los casos no hubo descubrimiento del yacimiento por el inversionista, quien compró las concesiones y denuncios, con excepción de Marcona que estuvo explorado y desarrollado y fue contratado para su explotación.

Mar 1, 1982

By Hernán Arévalo

El presente texto describe las perspectivas en la utilización de la tecnología de conversión del carbón en los países latinoamericanos para producir petróleo sintético y derivados. En ese sentido, el proceso de gasificación carbón y síntesis en combustibles líquidos es costoso. Por ello, se requiere un análisis económico cuidadoso antes de decidir la instalación de cada planta en los países en América Latina y en el que los institutos geológicos y del carbón de los países de Latinoamerica inicien o continuen, según sea el caso, con la exploración de los recursos carboníferos para determinar reservas, incluyendo las de los carbones hidrocarburables.

Mar 1, 1982

By Jaime Mercado

"El presente texto señala los yacimientos de cobre de tamaño medio, que por su especial ubicación geográfica son de importancia regional y nacional su desarrollo. Dichos yacimientos están ubicados en la faja costera de Arequipa (Condestable, Raúl, Río Seco, Monterrosas, Acarí y Chapi) y Lima. Además de estos yacimientos, existen otros, cuyas reservas y potencial no están determinados. Sus principales características son: proximidad a la carretera Panamericana, puntos de embarque de primera importancia, depósitos de almacenamiento de ácido sulfúrico, energía eléctrica del Mantaro y Charcani en proceso de ejecución. "

Mar 1, 1982

By Paul D. Tomlingson

Maintenance costs in the mining industry often account for as much as 18-20% of total operating costs and with the cost of labor and materials rising, they threaten to become an even larger percentage of the total. Yet, without an effective maintenance program costs can soar beyond what they would be without a program. In other words, when production equipment is down, there is no production and no product to sell in the marketplace. This cost of downtime in lost product far exceeds the actual cost of maintenance, which is defined here as labor and materials. Thus, mine management must have an effective maintenance program to avoid downtime and meet production targets. Attaining an Effective Maintenance Program Many mine management and operations supervisors believe that an effective program is a function of how hard they push maintenance. Yet, when vital production equipment is inoperable and production is lagging, no amount of pushing helps. In actuality, maintenance has little control over its own destiny and needs support from other departments to deliver good service. Success of the maintenance program depends on gaining control of those factors that directly influence maintenance. Consider the following. Organization-The maintenance organization must be structured for maximum responsiveness to production needs. Unfortunately, some needs are immediate and many are unknown in advance. The maintenance department has little control over them. These outside influences limit the department manager&apos;s ability to control his own organizational structure. Preventive maintenance procedures-Routine lubrication, equipment inspection, minor adjustments and the like are controlled mostly by maintenance. Yet, scheduling preventive maintenance depends also on the availability of equipment controlled by other departments. Planning-The purpose of planning maintenance jobs is to ensure that the best use is made of maintenance resources. If the production department creates an environment of running repairs and emergencies, there can be little planning. Even well-planned jobs will suffer if there is less than full cooperation in carrying them out. As a consequence, the maintenance department is not blocked from planning, but the value of its planning is reduced. Scheduling-Maintenance scheduling should be a joint effort. Although maintenance does the planning, production must agree to the scheduled maintenance of its equipment. Workload-As a service organization, the maintenance department has limited control over its workload because it must consistently respond to other department&apos;s demands. At best, maintenance controls only the fixed portion of its workload-utility work, janitorial service, maintenance shop work, and assigned repetitive and preventive maintenance duties. Unscheduled and emergency work are initiated by operations. Major maintenance actions require full cooperation. Labor productivity-The effective use of labor is tied to other key functions of maintenance. These include organization, preventive maintenance, planning, scheduling, and emergency work. An area type organization, for example, can often respond more quickly to immediate needs than a centrally controlled maintenance group. Yet, area maintenance can result in lower labor productivity unless tight control is exercised. One of the advantages of a good "detection-oriented" preventive maintenance program is early discovery of problems and better opportunity to schedule corrective work in advance. Under planned work conditions, use of labor can be more productive. Complete planning and scheduling can minimize time spent on each job, increase effectiveness of supervision, and improve labor productivity. Finally, if emergency work is minimized, there are fewer delays, less lost time, better coordination, and more productive use of labor. While labor productivity is an important factor in carrying out maintenance, it also is influenced by outside factors. However, few realize the impact of being able to improve maintenance productivity. By improving the productivity of 30 men from 30% to 40%, maintenance could accomplish the same work value as if it had added 7.5 men working at 40% productivity. 30 (1800) (40%) = 21,600 man-hr/yr 30 (1800) (30%) = 16,200 man-hr/yr Difference = 5,400 man-hr/yr 1800 (40%) 7.5 men Leadership-The maintenance department can have significant control over its own leaders, the front-line foremen, but they must

Jan 12, 1982

By Katzer R. Klimpel, J. Sewell

Dr. Roussey Roussev The use of chemical additives on grinding is of significant importance considering the high energy consumption of grinding processes. My research indicates that the dispersant approach explains the effects, in this particular case of wet grinding. Further, the dispersant approach combined with torque measurements give the possibility of clarifying the mechanisms involved when using grinding aids. I find the conclusions derived from the data obtained to be correct and useful for grinding. In general, I agree with the explanations. However, I would like to discuss several additional points that I consider to be important, and in the same time to mention some of my own results from investigations similar to those presented in the study under discussion. The "bed volume concept" and the change of slurry viscosity explain adequately the data plotted on fig. 3, in conjunction with Figs. 1 and 2. However, the significant increase of the average torque in the case of 83% solid with XFS-4272 introduces the necessity of establishing the optimum of percent solid when dispersant is used. For example, the optimum percent of solid for different materials varies. One of the reasons is the material&apos;s mass density. On the other hand, it is necessary to determine the concentration of the chemical used. Because of this, it would be interesting to know how the cited concentration was selected. The supportive discussion and verification by Dr. Roussev, with results similar to that of the paper, is appreciated. I will try to answer the additional questions he has raised. To begin with, the mill was fitted with six lifters of approximately one-quarter inch height. There has been extensive lab and plant level work to understand downstream influences of using dispersants like XFS-4272*. In sulfide ore processing, which is the area in which most industrial scale testing has been performed with this approach, neutral to positive influences have been observed. For example, positive effects (e.g., increased recovery) have been noticed in flotation operations involving ores that have a tendency to produce excessive slimes upon grinding. (1) Also, the use of a dispersant has been shown to demonstrate a positive influence on classification by improving the sharpness of separation and preventing a decrease in d50 value that usually accompanies increasing flow rates to classifiers.(2) The biggest potential downstream problem is in thickening, which at the dosages involved, has not been a problem in plant scale usage. The commercial price of dispersants like XFS-4272 is quite variable depending on source, concentration, etc, but a typical cost of XFS-4272 to achieve a 10% increase in throughput in industrial mills has been between 20 and 35- US per ton of feed ore (1981).

Jan 12, 1982

By J. D. Miller, R. J. Smith

Earl C. Herkenhoff Publication of the article "The Flotation Behavior of Digested Asphalt Ridge Tar Sands" by R.J. Smith and J.D. Miller has confirmed and again spotlighted a most significant and important development in the field of tar sand and heavy oil mining. This is the ability to recover 95 % of the bitumen in dry tar sands by a hot water process. The initial investigation by Miller and Sepulveda in early 1978, "Separation of Bitumen from Dry Tar Sands," was the first blockbuter. It is disappointing that there has been so little scientific and industry ackowledgement that the authors laid to rest the long entrenched belief that the sand grains had to be "water wetted" for a hot water process to be applicable. Dr. Miller and his researchers at the University of Utah used slightly different mineral dressing terminology in describing their process but it is essentially the old, established technique of high solids attrition scrubbing at elevated temperatures with a conditioner or modifier, followed by dilution and froth flotation. Similar techniques were described in detail for other nonmetallic minerals in the mid-1940s by Stuart Falconer of American Cyanamid Co. The authors used a 15-minute "scrub" period (or in their terminology "digester step") at 73% solids and 95°C (203°F) in a 0.3 m solution of sodium carbonate -about 4 kg/t (8 lb per st) of tar sand. Flotation was at 10% solids. Obviously, the scrub is an expensive step with respect to energy input but the high recovery of bitumen appears to justify it. Two basic questions then arise: • What are the effects of shorter scrubbing time, lower temperature, and less sodium carbonate? • Would a two-stage approach be advantageous? That is, could you get the major proportion of the bitumen with a mild scrub and apply the high power and temperature only to the refractory portion? These variables should be evaluated. Apparently, all results were only for rougher flotation. What would the grade and recovery of bitumen be if multiple cleaner flotation steps were employed? We must concede that a 60-62% grade of bitumen leaves considerable room for upgrading. Finally, it should be noted by all executives who approve funds for heavy oil recovery schemes, most of which are variations of in-situ methods, that mining can yield a 95% recovery of bitumen. That is correct, 95%. Imagine what that does to the total barrels recovered from a heavy oil resource compared with the scrawny 30-35% maximum recovery we are getting now. The conclusion-let&apos;s mine heavy oil and tar sands. Reply by R.J. Smith and J.D. Miller We, too, share Mr. Herkenhoff s enthusiasm for the mining of tar sands-heavy oil and continue the development of related processing technology. Specifically, it will be noted that by appropriate control of bitumen viscosity in the feed (probably the most important variable for successful separation) the recovery can be accomplished at low digestion temperature and low addition of alkali. A 91 t/d (100 stpd) pilot plant based on our technology is now being operated by Enercor in Salt Lake City (Hatfield, Oblad, and Miller, 1982). In these same pilot facilities, rougher concentrates containing more than 80% bitumen on a dry basis are being produced from Asphalt Ridge Feed. However, the processing of certain other tar sands results in incomplete digestion of bitumen/sand aggregates as discussed elsewhere (Miller and Misra, 1982). Such undigested aggregates are shown in Fig. 1. In this regard, it is intended that a recycle stream will be installed in the pilot plant to provide for redigestion of middling products. Further details regarding surface chemistry aspects of this tar sand technology have recently been published (Misra, Aguilar, and Miller, 1981). References Hatfield, K.E., Oblad, A.G., and Miller, J.D., 1982, "Pilot Plant Recovery of Bitumen from Oil Wet Tar Sands," Processing, Second International Conference on Heavy Crude and Tar Sands, Caracas, Venezuela, Feb. 7-17. Hatfield, K.E., Oblad, A.G., and Miller, J.D., 1982, "Pilot Plant Processing of Oil-Wet Tar Sands," Symposium, Rocky Mountain Fuel Society, Salt Lake City, Utah, Feb. 18-19. Miller, J.D. and Misra, M. 1982, "Hot Water Process Development for Utah Tar Sands," Fuel Processing Technology, Vol. 6, No. 1, April, pp. 27-49. Misra, M., Aguilar, R., and Miller, J.D., 1981, "Surface Chemistry Features in the Hot Water Processing of Utah Tar Sand, Proceedings, "Symposium of Separation Science and Technology for Energy Applications," Gatlinburg, Tennessee, May 5-8.

Jan 11, 1982

By Thomas J. Neil, O&apos

Most analysts find that progress has been evolutionary in any technologic field. To be sure, a few discrete breakthroughs can usually be identified, but viewed in its entirety, the curve of technologic progress over time tends to be relatively smooth with few discontinuities. Even in those cases where a major scientific discovery is achieved, the rate of technologic progress is limited by the often surprisingly slow rate of commercializing the concept into usable products. Whereas discovery and invention tend to be discrete events, technical innovation is often a painfully slow process. In spite of overall gradual change, technologic progress in most fields, when viewed in retrospect, tends to reveal certain relatively homogeneous periods where little change is evident, separated by episodes of accelerated progress. Thus, open-pit mining over the past century has changed from predominately train haulage to truck haulage and is now experiencing a major increase in belt haulage. Ore reserve estimation is another field that fits the same pattern, and the history of mine evaluation lends itself to a similar analysis. Evaluating mine investment opportunities is a fascinating aspect of mining. The unique set of risks inherent to every mining project is particularly intriguing. Geologic risks are most obvious, since faulty ore grade and tonnage estimates are among the leading causes of mine failures. Wide swine&apos;s in mineral commodity prices are usually cited as another major risk in mining. Because any ore deposit is a finite resource and the miner has limited discretion in selecting a mining sequence, mines are generally at the mercy of notoriously fickle commodity markets. There is a tendency for many mine investment analysts to feel that mineral market uncertainties are unprecedented in severity. Of course, prices in other markets rise and fall also-in some cases as precipitously as with minerals. However, two other mining characteristics tend to compound this marketing risk. First, the preproduction development period for a new mine is characteristically long. Under extremely favorable conditions, a significant mine may be developed in as little as two years, but the norm is four to six years or more. Second, mining is among the most capital intensive industries, consistently ranking near the top among all industrial sectors in assets per employee, and near the bottom in annual sales dollars per dollar of assets. Thus, mine investors typically have large sums invested for a long time before the outcome of the venture is determined by notoriously unpredictable markets. This is not a business for the faint of heart, and the importance of sound investment decision making is obvious. The high risk and technical complexity of mining operations have combined to require greater attention to financial evaluation by mining engineers than by most engineers in other specialties. Nearly all early mining engineering textbooks dealt with problems in mine valuation in a detailed manner; and, today, the sophistication of capital investment analysis is high in the mineral industries. Traditional Mine Valuation Methods Although some evaluation process has no doubt accompanied nearly every mine development throughout history, a formalized quantitative approach first emerged in the last half of the 19th century with the establishment of academic programs in mining engineering. The philosophy and approach to mine valuation that evolved at this time were, with periodic minor refinements, considered the standard for nearly a century. Only after 1960 did major changes begin to occur. The traditional approach to mine valuation reflected the investment community&apos;s historic attitudes toward risk. Mines were generally considered too risky for debt financing, and virtually every new mine was financed from internally generated funds or new equity subscriptions. The investment evaluation methods that evolved focused on mining&apos;s higher risk relative to other

Jan 11, 1982

By Tom Skodack

Mine and tunnel contractors face a complex environment-one in which economic risks are high, operating costs grow ever higher, ore grades are lower or recovery more difficult, and civil construction projects are intensely competitive on a world-wide scale. Within the context of this environment, the risks and rewards of proper machine selection for rock excavation have become proportionately large. Speed, depth and scope of analysis, and extensive supporting information are indispensable in the selection process. Equipment designs and their applications are also myriad and diverse. Several equipment alternatives and excavation techniques may have to be evaluated at once to choose the most cost-efficient approach. The following examples are typical of the current demand for more detailed equipment analysis: • An aggregate supplier starts a new quarry. He knows his targeted tonnage, blasting restrictions, and previous operating costs from other quarries. But he must improve on his old costs. What drill pattern, hole size, and bench height will give lowest cost per ton? How many crawler drills and what type will produce this tonnage most efficiently? • A mine is using a fleet of twin pneumatic ring drills for long hole drilling to initiate their cave. The mine is facing both air shortages and increasing operating costs with decreased efficiency in the ring drill fleet. If they invest in new hydraulic long hole drills, what impact will each drill unit have on production? Each twin drill unit? What configuration gives best operator efficiency and subsequent reduction in manpower? Which configuration gives the best return on investment? • A tunnel contractor is bidding a long straight water tunnel by conventional drill and blast methods. What is the optimum number of drill booms for the tunnel cross section and excavation schedule? How many rounds per day can he achieve? What are his total project drill, blast, and muck costs? In the past, such questions could be answered, but only approximately at best. One good prediction could involve many hours of laborious calculations that had to be repeated each time a new parameter was introduced or an existing parameter changed. In 1980, increasingly complex analysis, coupled with increasing need and quick response times demanded by industry, led Atlas Copco&apos;s project department to turn to the computer. New computer programs based on theoretical considerations and three decades of worksite performance data were developed for evaluating mine and tunnel contractors&apos; equipment needs, productivity, and partial or total operating cost calculations for most conventional drill and blast excavation techniques-including shot rock loading and transportation. This Computerized Analysis of Rock Excavation-or CARE-program has since been available to the mining and construction industry. From each program specific results can be pre- dicted, including: • Productivity Calculations-Rock drill penetration rate for a given drill, hole size, and rock type, optimized for the best drill steel life; net machine productivity (drill-out time or drill meters-footage-per shift); total drill round time, including charging, blasting, loading, and haulage; suggested drill pattern, computer printed, including hole size for a given rock drill, rock type, and associated blasting restrictions for either drift rounds or benching applications; long-hole drill meters (ft) per drill shift; breasting down (upper drilling) drill meters (ft) per drill shift; and comparison between continuous loading machine capacity and LHD capacity. • Operating Cost Calculations-Operating costs expressed as cost per drill meter (ft), cost per cubic meter (cubic yard) of excavated rock, and cost per meter (ft) of tunnel advance. These costs may be calculated using as many cost centers as the mine, quarry, or tunneling contractor wishes. Specific operating costs may cover drill rig operating costs only, less capitalization; drill rig operating costs, including amortized equipment investment; drilling and blasting costs; drill, blast, load, and haulage operating costs; long-hole drilling operating costs per drill meter (ft) or per blasted cubic meter (cubic yard) of rock; and loading and transport operating costs. In all the above cases, any number of cost and capacity calculations may be run by simply changing important cost center variables to judge their net effect. Accuracy as a Function of Input Data and the Statistical Data Base Accuracy of a projection clearly depends heavily on the data base from which the projection is drawn.

Jan 11, 1982

By E. L. Fidler, T. E. Finch

Wayne Anderson Regarding the technical paper by Thomas E. Finch and Edward L. Fidler, "Recovery of Stray (Thin) Seams in Western Coal Mining." I would like to comment on this subject. In western Canada, most strip mines encounter thin seam coal or rider seams. Although the paper addresses the problems and costs associated with the recovery of this coal, it does not take into account what the savings are. Without looking at the savings, the "Total Objective" is of course not clear. I feel that in a stripping operation the mine can spend per ton (of the thin seam) up to their dragline stripping costs per ton to recover a rider seam or thin seam. The reasoning behind this is simply that this is the price the mine will have to pay to expose an equivalent amount of coal without the recovery of these thin seams. If the mine can recover a rider seam or thin seam for less than the dragline operating costs per ton, a savings will be realized. By recovering a thin seam or rider seam, the life of an ore body is extended by that amount of coal not thrown away. In addition, the cost of land acquisition, associated permits, capital, and reclamation will be reduced as more coal is delivered for a given area. When the above points are considered, the recovery of these thin seams can be very profitable and indeed worth recovering.

Jan 11, 1982

By James M. Link

The first rule of mineral deposits always seems to be: the deposit is never close to the market. With gems and precious metals, this is not much of a problem. But with most of the mineral commodities used in today&apos;s world, transportation becomes a major part of the cost to the consumer. In Japan, for example, more than 60% of the cost of coal to the consumer may be attributed to transportation. The purpose of this article is to examine pipeline transportation, particularly mineral slurry pipelines, as a means of getting the mineral to market. Pipelines Today Regulated pipelines in the US totaled nearly 724 Mm (450,000 miles) in 1980 according to the Federal Energy Regulatory Commission (FERC). Worldwide, more than 210 Mm (125,000 miles) of new pipelines will start construction in 1982 at an estimated cost of more than $150 billion. According to the Bechtel Corp., the period between 1982 and 2000 will see major growth in pipelines of all kinds. In North America, major movements of crude oil from Alaska and synfuels from the Rocky Mountains will require the construction of nearly 16 Mm (10,000 miles) of new pipelines. Nearly 42 Mm (26,000 miles) of new gas transmission pipelines will be needed to tap both US and Canadian arctic gas fields and move the gas to major markets on both coasts. Other pipelines will be required to move additional quantities of natural gas from the Rocky Mountains to more populous regions. Bechtel says more than 24 Mm (15,000 miles) of slurry pipelines will be needed to transport coal from both eastern and western coal provinces to the Mississippi valley and coastal areas. In 1980, 125 companies delivered more than 1 km3 (6.5 billion bbl) of crude oil and 652 hm3 (4.1 billion bl) of products in the US. At the same time natural gas pipelines transported 498 km3 (17.6 trillion cu ft). The reported investment by these companies was nearly $20 billion at the end of 1980. Advantages of Pipeline Transportation The obvious success and vitality of the oil and gas pipeline industry is based, at least in part, on the fact that pipelines are a very efficient and low-cost method of transportation. This fact, coupled with the need for lower cost trans¬portation, has led to the marriage of oil and gas transmission technology and the bulk mineral solids transportation industry. The off-spring of this marriage is the mineral slurry pipeline. Slurry pipelines have a number of advantages over other transportation methods. One of these is the fact that they are buried-out-of-sight, out-of-mind. Second, they are relatively small users of labor because they lend themselves to automation and remote, or even computer control. Third, they offer an attractive economic alternative to other transportation systems. For example, for a 1000 km (621 miles) distance, rail costs of 1?/ km (1.7?/ton-mile) are about equivalent to slurry pipeline costs. But, as the distance increases, pipeline cost per t-km continues to drop while equivalent rail charges remain essentially insensitive to distance. Where existing rail, barge, or ocean ships are available, the cost of new construction associated with a slurry pipeline probably will render it noncompetitive. However, where new rail or other construction is needed, the cost of a slurry pipeline is very competitive. About three-fourths of the cost of a pipeline is in pipe, fittings, and construction. Nearly a fifth of the investment is in pump stations and the remainder is in right-of-way, surface facilities, utility acquisition, communication facilities, and other support areas. The fact that pipelines are capital intensive is, at the present time, a mixed blessing. For example, the delivered cost of coal in a hypothetical project doubles when the cost of money rises from 9% to 17.5% per year. The largest cost element for delivered coal in this example is in depreciation and finance charges. The next largest cost element is electricity to power the pumps, with labor making up the smallest increment of the delivered cost of coal. World Slurry Pipelines The idea of a slurry pipeline was probably first investigated in the latter 19th century, but the first ones were successfully built and operated in the US in the early 1900s. Today, they are fairly common worldwide. Table 1 shows a number of the world&apos;s slurry pipelines. An examination of these will further emphasize the fact that pipelines provide a cost competitive alternative where new construction of a transportation system is required. In each of the examples, the desired mineral commodity is located in a remote corner of the world, markets are at a great distance, value of the commodity is not great, and no other transport system is available.

Jan 10, 1982

By Peter J. Szabo

Many mining engineers tend to think of the economic analysis of mining ventures and projects on an f.o.b. mine basis. This is especially true of mines that are operated in an established domestic mining district. Here, transportation costs are many times smaller in comparison to overall delivered prices. One has only to consider the development economics of taconite mines in Minnesota with production destined for lower lake ports to see the truism of this statement. In the international arena, however, with consumers such as Japan and Europe located thousands of miles from source countries such as Brazil and Australia, the situation is different because mineral transportation is often a critical factor in determining project viability. This article is being presented to provide a basic understanding of the factors that govern ocean transportation of the three largest bulk mineral commodities shipped around the world: iron ore, coal, and phosphate. The major dry bulk commodity trades as a percentage of volume shipped are iron ore, 45%; grain, 25%; coal, 20%; phosphate rock, 5%; and bauxite and aluminum, 5%. Most of these commodities are carried by bulk carriers rather than tankers. These are vessels that have cargo, usually in solid form, loaded directly into the hold of a vessel by shore-side materials handling facilities or, in the case of a geared bulk carrier by the vessel&apos;s cranes and derricks. Gearless bulk carriers are used in most cases for iron ore and coal. Geared bulk vessels are mainly used for minor dry bulk trades such as ore concentrates (copper, lead, zinc, etc.), fertilizers (phosphate, potash, etc.), cement, petroleum, and coke. There has been, however, a trend toward using more self-unloading ships in both iron ore and coal ocean transport. And large vessels, such as the Universe Kure of Japan, have been designed with a cargo capability of 157 kt (155,000 dwt (deadweight tons)). Trade patterns of major bulk commodities are influenced by the Panama and Suez canals. Both of these canals have draft limitations that prohibit large, deep-draft, ocean-going vessels from using them for shorter trade routes used by Panamax and Suex vessels. The shipping industry has developed two widely used vessel classes; the Panamax and Suex vessels. The former is the maximum size vessel that can pass through the Panama Canal, usually 51-61 kt (50,000 - 60,000 dwt), depending on the season and draft of the vessel. The Panama Canal is usually 0.6-0.9 m (2-3 ft) deeper in the winter than in the summer. Thus, less cargo can be carried by the same size ship in the summer through the canal than in the winter. The Suex vessel is in the 71-81 kt (70,000-80,000 dwt) class. This larger vessel is able to transit the Suez since Egypt deepened the canal following the Seven Days War. Recently, the Suez Canal has been deepened to accommodate vessels with drafts as deep as 152 kt (150,000 dwt).

Jan 10, 1982

By Ernest E. Thurlow

Introduction Today, more than 50% of rail-carried commodities are mineral industry related, with coal being the most important single commodity moved by rail. In 1980, coal accounted for more than 5.7 million of the total 22.6 million carloads moved by rail. Metallic ores were third behind grain, with more than 1.4 million carloads. Crushed stone, gravel, sand, and other non-metallic minerals totaled almost 2.3 million carloads. Chemicals and allied products, including fertilizer and coke, added another 1.7 million cars, with petroleum and petroleum products totaling 300,000 carloads. Coal Several things happened in the 1970s that gave rise to increased consumption of coal-particularly western coal-and to its dominant position among rail-carried commodities. First, the Clean Air Act of 1970 required generating plants to make significant reductions in sulfur dioxide emissions. To comply, utilities could either invest in scrubbers or switch to low-sulfur western coal. Many opted for the latter. By 1972, increasing demands by the utility companies halted what had been a 25-year decline in national coal consumption. Second, the Arab Oil Embargo of 1973 put an end to cheap oil and gas, limiting their future as fuels for electric generating purposes and increasing the potential for coal. Third, in 1977, President Carter announced an energy program with coal as its cornerstone, calling for an annual two-thirds increase in national coal production by 1985. He also called for conversion to coal by utilities and large industrial users. Finally, he proposed a 10-year, $10 billion program to encourage domestic coal production and stimulate development of export markets. Coal bounded into world prominence. Foreign demand for steam and metallurgical coal increased tremendously, while US demand for western coal also shot up. This meant greater demands on the transportation sectors that traditionally carried coal to market. Many railroads began programs to serve the coal industry. One example is Burlington Northern&apos;s commitment to handle increased western coal tonnages. The company spent more than $1 billion in recent years to develop a system capable of moving more than 91 Mt (100 million st) of coal each year. Other leaders in this renewal were Norfolk and Western, Union Pacific, Santa Fe, and Southern Pacific railways. The importance of the rapid growth of coal traffic to the railroads is shown in the accompanying table, which gives percentages of total tonnages hauled and revenues attributed to coal. With coal providing the railroad industry with a substantial share of its revenues, there is keen competition among the rail companies themselves and among railroads and other transportation sectors for coal haulage. But there is also cooperation when more than one railroad is involved in delivering the coal from mine to market or when a combination of transportation modes is more economical. The latter is represented by Conrail&apos;s interest in working with the port authorities of New York and New Jersey to establish a new coal port that would serve not only export markets, but also utilities and industries in the northeast. Iron Ore Next to coal, iron ore (taconite) is the most important single mineral commodity handled by railroads. In Minnesota, where most iron ore is produced, rail transportation is primarily by Burlington Northern and the Duluth, Missabe, & Iron Range Railway Co. (DM&IR). The DM&IR, owned by US Steel, serves several producers on the Mesabi Iron Range. Two of the larger producers, Erie Mining Co. and Reserve Mining Co., also own railroads that operate between the mines and the ports of Silver Bay and Taconite Harbor on Lake Superior. Several iron mines and taconite plants in Michigan are served by the Chicago and Northwestern, and the Soo Line. Total 1981 shipments of taconite and iron ore are estimated at 55.9 Mt (55 million It), compared with about 61 Mt (60 million It) in 1979 the most ever shipped in one year. Still, with annual production capacity of the eight Mesabi Range

Jan 10, 1982

By A. T. Yu

Two major events highlight recent developments in US ore and coal ports: completion of the last series of modern taconite pellet transshipment facilities on the Great Lakes; and modernization and construction of coal ports, particularly on the East and Gulf Coasts. The New Taconite Transportation System To reduce raw material transportation costs, a fleet of new generation high-capacity 304-m (1,000-ft) self-unloading vessels were built to carry iron ore pellets from the Minnesota-Michigan iron ranges to the steel plants on the lower Great Lakes. Existing port facilities had to be modernized, revised, or completely rebuilt to accommodate these large vessels. Some of these were Burlington Northern&apos;s Allouez, WI, loading dock; Duluth, Missabe & Iron Range Railway Co.&apos;s Two Harbors, MN, facility; Republic Steel&apos;s Lorain, OH, facility; and Chessie&apos;s Toledo, OH, dock. Allouez and Two Harbors receive taconite pellets from unit trains and load them onto large vessels either after dumping or via a large stockpile and reclaim system. The Lorain facility receives iron ore pellets from self-unloading vessels&apos; discharge boom conveyor and reloads the pellets into rail cars or small vessels destined to inland steel mills. The Toledo facility receives Armco pellets from vessels, stockpiles them through the winter, and reloads into unit trains destined for Armco&apos;s mills along Chessie&apos;s rail tracks. Burlington Northern&apos;s $75-million Allouez pellet dock, completed in June 1977, was built to receive pellets produced by Hibbing Taconite Co. and National Pellet Plant in Minnesota, stockpile them through the winter when the lakes are frozen, and load them into 304-m (1,000-ft) vessels in the shipping season. As much as 10 Mt (11 million st) of pellets may be stockpiled within the loop track. A 6-km (4-mile) long conveyor system connects the stockpile area and the dock. Thirty-six new concrete silos were built on the dock to house 2 kt (2,000 st) each of pellets before shiploading. The $35.5-million expansion of the Two Harbors transshipment facilities began shiploading in July 1978 after ground breaking in Aug. 1974. Particularly noteworthy is the first application of the Orboom system-a breakthrough in technology for the modernization of the century-old pocket docks on the Great Lakes to accommodate the new generation of super vessels. The pocket-type loading dock has been a standard on the lakes for nearly a hundred years. Bottom-dump rail cars fill the ore pockets on top of a finger pier. Gravity chutes matching standardized ore ship hatch spacings are lowered to fill the holds of a 20.3-kt (20,000-dwt) ship. The construction is simple and the loading swift. In spite of advances in technology elsewhere, most of these docks continue to serve the iron ore and coal trade in the same manner they did in the 19th century. Although performance of the pocket docks on small vessels remains outstanding, the new 304-m (1,000-ft) vessels are beyond the reach of the old docks. After extensive development, the Orboom system (Patent No. 4,065,002) for pocket docks was successfully developed. The heart of the Orboom system is the retractable shuttle loading arm which loads the wide beam vessels. The Orboom shuttles are fed by existing pockets of the dock that, in turn, are charged by a tripper conveyor along the length of the dock. The Two Harbors shiploading system is supported by a 0.9 Mt (1 million st) storage-reclaim network. Unit trains are bottom dumped. Taconite pellets are stacked and reclaimed by bucket wheel reclaiming systems. Lower Lakes New Ore Ports At the lower Great Lakes receiv-

Jan 10, 1982