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By G. S. Grainger, R. A. Cummings, F. S. Kendorski, R. L. Butts

Georgia Power Company's Rocky Mountain Project, located approximately ten miles northwest of Rome, Georgia, in the Valley and Ridge Physiographic Province, is a pumped-storage facility rated at approximately 800 megawatts of peaking energy. Geological field explorations and borings enabled the division of the rocks along the tunnel and shaft alignment into distinct lithologic units and defined the ground--water regime. Field explorations included a detailed analysis of the rock mass discontinuities at available rock unit exposures. Testing of rock strengths was performed in several phases in both the field and the laboratory. The field testing consisted of point-load testing, geophysical testing, in situ load testing, and hydro-fracture testing. Laboratory testing determined the Brazilian split-tensile strength, the unconfined compressive strength, the triaxial compressive strength, the joint-direct shear strength, and the pulse velocity. The rock mass along the tunnel and shaft was also characterized by empirical classification systems. The classification systems included the Rock Mass Rating (B1IR) and the Rock Mass Strength Determination (RHSD). The results of the field explorations, field testing, laboratory testing, and rock classifications were used to divide the rocks into two structural groups. These rock groups were defined as volumes of rock wherein the rock mass behaves similarly in response to the excavation. Each group, therefore, required separate rock engineering consideration.

Jan 1, 1986

By L. M. Petrie, D. C. Marozas, S. E. Paulson

The US Bureau of Mines (Bureau) is conducting research to evaluate the potential for developing an in situ leach mining process that will selectively extract manganese from oxide ores, leaving gangue relatively undisturbed. To accomplish this, a geochemical approach based on deposit-specific information, such as mineralogy and geology, is used to constrain the operating parameters of the system. Among the studies being conducted are: • leaching experiments to define reaction mechanisms and kinetics, • detailed petrologic characterization at the microscopic scale to assess manganese distribution and leaching efficiencies, • deposit characterization and evaluation, and • development of potential manganese recovery schemes. Data from these studies are being used to develop engineering design information for an in situ mining process. Specific details of the Bureau's research project are discussed, including results obtained to date.

Jan 1, 1993

By K. T. Dreher, J. A. Brierley, C. L. Brierley

Water from underground uranium mines located in the Ambrosia Lake district near Grants, New Mexico, U.S.A., is treated to reduce levels of uranium, selenium, radium and molybdenum. The treatment system consists of a series of ponds and an ion exchange plant. Bacterial and algal populations present in the pond system are considered agents which actively assist in removal of the pollutants present in the water. Pondbottom sediments maintain a reducing zone and a large population of sulfate-reducing bacteria of the genera [Desulfovibrio] and [Desulfotomaculum]. Uranium, molybdenum, and selenium accumulate in the pond sediment. Stimulation of the microbial sulfate-reducing activity resulted in a decrease of soluble concentrations of these elements in laboratory systems. Predominant components of the treatment ponds’ algal flora are the filamentous [Spirogyra] and benthic [Chara]. Laboratory study indicates that [Spirogyra] is more active than [Chara] in removal of uranium and molybdenum from solution. However field-collected algal samples of both of the genera contain uranium and molybdenum. Laboratory studies indicate that death and decay of the algae in association with pond sediment does not result in return of cellbound uranium and molybdenum to the water. The algae appear to act as bio-filters for accumulation of particulate pollutants and agents for adsorption and/or absorption of soluble pollutants.

Jan 1, 1980

By A. L. Boerner

Off-highway tire costs represent a significant portion of the total mining costs in openpit, truck-shovel operations. To extend the lives of tires, the site-specific factors influencing tire life should be investigated Valuable data can be obtained by combining historical operational data captured by a mine dispatch system with detailed tire and maintenance histories. Assuming that failure counts satisfy a Poisson distribution, F-tests can be applied to determine significant deviations from desired or target counts. The methodology developed in this paper can be used to identify the haul routes and loading and dumping zones that have significantly higher incidences of tire failure. Corrective action can then be targeted at these zones by modifying the shovel or truck operator practices; changing the haul route maintenance and clean up practices; or altering the bench, ramp or waste dump design parameters. An example is given of the correlation of tire separation and tire impact failures with haul routes for a fleet of nine Caterpillar 793C trucks in operation at the Chuquicamata Mine in northern Chile. A high incidence of impact failures was observed for the ex pit ore crusher and for tires installed in the left outer rear position on the trucks. The latter was postulated to be due to a preference for drivers to execute right-hand turns prior to dumping. Recommendations were made to revise crusher and dump cleanup practices and investigate the feasibility of super-elevating the surface of dumping zones to reduce ground pressure on the left rear tires.

Jan 1, 2002

By R. K. Singhal, R. D. Lama

Underground coal mining systems have kept pace with developments that have occurred in other types of mining. A diversified group of machines are now available with high horsepower motors, built-in microprocessor technology, and numerous options to satisfy miners' needs in various geological environments. The results will be a greater degree of mechanization and recovery of coal from inclined seams, thins seams, and seams mined in lifts from shallow as well as deeper deposits. This article is based on a general suvey carried out by the authors to detemine the current status of mechaniztion and systems development in underground coal mining. It indicates that the next two decades will see increasing use of longwall mining, which has already reached a high degree of sophistication. Automation, remote control, and robotics are the key words of the future. Data transmission from underground to surface and over long distances will be almost routine. Many components of the high technology industry that are just being considered by the mining industry regarding equipment health and perform¬ance monitoring, quality control, application of expert systems, and computer networking will become a routine part of underground mining technology. Within the next 21 years, "manless" mining, first attempted about 25 years ago, will become a reality. References to any trade name are meant to aid understanding of the text and do not imply endorsement by the authors or their users. Current coal face developments Developments in underground mining equipment, its application, and associated technology have made phenomenal progress compared to those in other types of mining. Room-and-pillar systems, on one hand, and longwall mining, on the other, have sophisticated equipment at their disposal. Both of these systems have become highly productive, with output per manshift about 50% higher than that achieved a decade ago. Continuous miners continue to be the mainstay of room-and-pillar coal mining. Numerous developments, how-

Jan 1, 1989

By C. John Dunnicliff, Birger Schmidt

INTRODUCTION To be effective and useful, monitoring of tunnel construction must be carefully planned throughout all steps. A vital and frequently overlooked step is a clear definition of the specific purposes of the instrumentation. Most tunnel construction monitoring has in the past been of benefit to research, the advancement of tunneling practice, wittingly or not. The development of monitoring instrumentation for the benefit of the project from which the data are recovered has very significant potential for risk and cost reduction of soft ground tunneling. A systematic approach to tunnel construction monitoring, from conception to full implementation, includes at least the following nine tasks or steps: Definition of benefits and purposes; design and project specification to draw full benefits; selection of monitoring parameters; selection of instruments and writing of specifications for procurement and installation; procurement and installation; reading and maintenance; data storage and retrieval; interpretation; implementation. Some of these steps are fairly easy and resolved through the use of established theories and technologies. The difficult ones are those that require the bending of minds, those that involve changes in the ways engineers design soft ground tunnels, the way owners pay for tunnels, and the construction is managed, inspected and controlled. Performance monitoring can be of benefit to the owner, design

Jan 1, 1974

By Louis C. Just, Grahan A. Mathieson

Low cost, greater operating flexibility, and relatively simple operation are just three of the reasons for using minicomputers in the mining industry. No less than a dozen US manufacturers have sold the new generation of minicomputers to mining operations in the US and the world. Many manufacturers produce several models of minicomputers, each with excellent calculating capabilities. Prices for these "mini-giants" range from about $10,000 for a basic system to over $300,000 for a very powerful, sophisticated system with numerous peripheral devices. While the acceptance of minicomputers by the mining sector has lagged behind their penetration into other businesses, mines with minicomputer capability-especially remote mine sites-have found applications in practically all areas of operations including standard payroll processing, mineral deposit modeling and planning, surveying/mapping, production reporting, and daily production scheduling. In fact, the only limit to the further application of minicomputers in mining is the user's imagination. There are some obstacles to the accelerated use of minicomputers in the mining sector: the limited amount of software available, limited information on site-specific uses, and limited interest in the mining market by manufacturers. The latter is especially significant in light of the fact that many manufacturers queried in a recent telephone survey did not compile statistics on locations of their units in mining. The general consensus is that mining sales represent less than 1% of the total market. Many manufacturers do believe that market dynamics will increase their future research and development for the mining industry. The minicomputer was introduced in 1968, when Digital Equipment Corp. of Maynard, MA, developed a small computing device-the PDP-8 minicomputer. It is important to note that since then, it has become increasingly difficult to precisely define a minicomputer (see box, page 1582). The mini has evolved to surpass the capabilities of many of the large computers (mainframes) of 1968, and some models rival the mainframes of today.

Jan 11, 1981

By Don Runge, John T. Zeni

Cuprex Limited is currently developing a small gold mining operation in Central Australia in the Tennant Creek field. In February 1984, the company undertook a feasibility study on the project and operations commenced in August 1984. Ore reserves are located between 230 and 280 metres (755 ft and 919 ft) below surface and ore extraction required the establishment of a shaft network for access, ore hoisting and ventilation. Zeni Drilling Company from West Virginia, U.S.A. was contracted to blind drill two shafts for the project. Blind drilling was selected for various reasons, including timing which related to cost efficiency. The blind drill shaft technique has proved successful in this application and with enthusiastic and innovative support from the mining industry, will prove an efficient and cost effective means of accessing and operating underground mining projects of all sizes in the future.

Jan 1, 1987

By S. K. Kawatra, A. K. Bakshi

Mineral suspensions in water show Newtonian flow properties at low percent solids. However, this changes to a non-Newtonian regime as the pet-cent solids increases. For Newtonian fluids, viscosity is independent of shear rate, hut, for non-Newtonian fluids, viscosity varies with shear rate. Therefore, if the slurry is non-Newtonian, attempting to measure the viscosity at a shear rate different from the shear rate experienced by the fluid within the process is futile. This is especially true for a hydrocyclone, where the rate of shear is different at different points within the hydrocyclone. In this case, it is very important to determine the flow type of the suspension before attempting to establish any correlation between the viscosity and the process efficiency. A new technique to distinguish such changes inflow type was developed. This involves two viscometers: a coaxial cylinder-type viscometer that measures apparent viscosity at low shear rates and a vibrating sphere-type viscometer that measures the apparent viscosity at high shear rates. For each of these instruments, special precautions were taken to allow, for the measurement of the viscosity of rapidly settling mineral suspensions. Because the vibrating sphere viscometer is operated at a much higher shear rate than the rotating viscometer, the two instruments together could determine the shear-rate dependency of the viscosity. Ground silica (80% passing 65 µm) in water was used to prepare slurries at concentrations ranging from 10% to 70% (by weight) solids. The viscosity of each slurry sample was measured simultaneously by both viscometers, and the results were compared. With this technique, it was found that all of the silica-slurry samples tested were in the Newtonian flow regime for up to 70% (by weight) solids. Methocel and Cellosize polymer solutions showed clear non-Newtonian behavior using this technique. This confirmed that non-Newtonian behavior of the silica slurries, if present, would have been detected by this arrangement.

Jan 1, 1997

By Jon T. Langstaff

The microseismic method of detecting instability and high-stress zones in underground mines was first developed in this country by the US Bureau of Mines in the early 1940's (Obert and Duvall, 1957). Early laboratory experiments showed that when competent rocks are stressed in a testing machine, the rock noise rate (number of rock noises per unit time) increases with increasing applied stress. This increase is more pronounced as the ultimate strength of the rock is approached. Subsequent testing of rock noises in underground mines confirmed this laboratory experience and much effort has been directed in recent years to make use of this property to develop a practical method of predicting rock failure. Investigations conducted in the Coeur d'Alene district mines have pointed out a definite relationship between the stress buildup in a rock mass caused by mining activity and the emission of audible and subaudible seismic activity (microseisms). In 1968, a concentrated joint effort by USBM Denver Mining Research Center and American Smelting and Refining Co. at Asarco's Galena mine was undertaken to verify several theories regarding the generation of microseisms (Blake, 1971; Blake, Leighton, and Duvall, 1974; and Kovacs, 1973). Findings indicate that (1) rocks under stress emit detectable seismic energy; (2) the energy source can be located using a triangulation method involving travel time differences to various receiving stations; (3) the rate of release of seismic energy increases with increasing stress; and (4) this increase in noise generally precedes a major rock failure (rock burst).

Jan 1, 1979

By Steven Tubbs

Steven Tubbs From mine to farm is a long journey for Florida's phosphate, but it is an important one to the American farmer who uses phosphate fertilizers to replenish the soil and produce the crops which eventually wind up on the American dinner table. In this phosphate-food connection, transportation plays a vital life-giving role, a role that is unique because of the large quantities of phosphate produced and the mineral's location in relation to its markets. Florida Leads World Florida is the world's largest phosphate producer, supplying 80% of the nation's and a third of the world's annual total. About 95% of Florida's phosphate goes into agricultural chemicals, with 90% going into fertilizers. Phosphate production is primarily concentrated in west central Florida, with the exception of mining and processing in north Florida by Occidental Chemical Co. The phosphate rock is beneficiated at the mine sites and then is transported out of Florida in a raw state, or to one of the industry's 18 chemical complexes where it is processed further. In 1981, Florida produced more than 42 Mt (46 million st) of phosphate rock-a 1% decrease from 1980. The industry also produced more than 12 Mt (13 million st) of phosphate chemical products in 1981 and transported them to both domestic and foreign customers. This year, the state's phosphate production and shipments are substantially lower than recent annual levels because of a depressed worldwide phosphate market. With production down slightly in 1981, shipments declined and company inventories increased dramatically. Phosphate-related shipments through the port of Tampa alone fell 20%. As a result, in 1982, phosphate operations cut production to reduce inventories. According to the Fertilizer Institute, during the fiscal year ending June 30, 1982, phosphate rock production fell 18%; phosphate rock shipments, 28%; finished fertilizer production, 30%; finished fertilizer shipments, 25%; and phosphate rock exports declined by 20%. Despite depressed conditions, Florida phosphate production and shipments are expected to increase in the near future with more rock being processed into fertilizer products. Phosphate is one of Florida's major industries. The US Bureau of Mines estimates it contributed $3 billion to the state's economy in 1981 and an additional $1.4 billion to the US economy. In addition, phosphate exports contributed to

Jan 10, 1982

By V. C. Rogers, K. K. Nielson

INTRODUCTION The potential health impact from uranium milling operations is mainly associated with long-term releases of radioactive contaminants from the mill tailings.(1,2) The major mechanisms for mitigating these potential releases focus on increasing the tailings containment with the addition of migration barriers such as thick earthen covers and clay liners. Some limited investigation has also focused on reducing the radionuclide source terms. This alternative approach has some desirable features, but stringent cost requirements are placed upon source removal methods in order for them to be economically favorable. A cost effectiveness evaluation is presented herein, in which costs for containment methods are used to establish maximum cost guidelines for the source removal methods. The 230U decay chain, shown in Figure 1 contains the radioisotopes of major concern, 230Th, 226Ra, 222Rn and its short-lived alpha-emitting daughters, When the uranium is removed in the milling process, these isotopes, which are normally not removed remain in the tailings solids. The general pathways to the environment from uranium mill tailings are depicted in Figure 2. The dominant pathways are radon to the atmosphere and radium and thorium to a groundwater aquifer. The magnitude of the contaminants released into these pathways can be characterized by the following parameters: 1. The 230Th and 226Ra content. 2. The emanating power for radon. The fraction of radon generated that is free to migrate. 3. The leach rates. Source reduction methods seek to reduce the magnitude of any or all of these parameters. In general the dose rates are proportional to the source terms. For radon production the source term is proportional to the product of the radium concentration, R, and the emanating power, E, so that the risk is reduced by the same factor that reduces RE. For example, if the radium content is reduced by 95 percent, but E is increased by a factor of two, then the dose rates are reduced by an order of magnitude. The source term for the groundwater pathway is not as easy to identify. The peak in the radium concentrations in the accessable water body can also

Jan 1, 1981

By B. Fitch, E. J. Roberts

Definitions and Terminology Classification is defined within this section as the separation of solid particles into size or weight fractions or classes by differential settling through a fluid. It is usually thought of as a size separation, but is actually made on the basis of particle settling rate, and so is affected by any variations in particle density and shape. The fluid may be liquid (wet classification) or gas (dry or air classification). This section will treat only wet classification. There are two basic types of classification; pool and hydraulic. In pool classification a suspension of feed particles is fed into and out of a pool of some kind at such a rate that only part of them¬ the coarser and faster-settling part-has time to settle out. The remain¬der overflows as fines. In hydraulic classification the feed suspension is introduced into or above one or more columns or pockets through which water is rising at a controlled velocity. Coarse particles subside through the pockets and are removed through spigots. Those which settle slower than the rising velocity in any column or pocket are (at least ideally) prevented from subsiding and so must overflow. Hydraulic classifiers or sizers are capable of making far sharper sepa¬rations than pool classifiers. The force causing settling may be gravity, or alternatively may be from centrifugal acceleration as developed in a centrifuge or hydra cyclone. Two things are needed to characterize the separation produced by classification: first, the size, D„ or equivalently the screen mesh at which it is made; second the sharpness of separation. Separation size may be defined in various ways. In closed-circuit grinding it is commonly specified by some point in the overflow screen analysis: For example, 5% on 65 mesh. In other applications, notably

Jan 1, 1985

By P. Massacci, F. La Marca, G. Bonifazi

Some deposits of inhomogeneous materials, which occur near the surface and are exploitable by open-pit mining, may he characterized in real time prior to mining through groundsurface imagery. If the slice to be stripped is not overly thick, surface texture and color properties may be extrapolated to its entire thickness. Image-analysis techniques for processing ground-surface images acquired in situ or in the laboratory shortly after their acquisition have been developed. These images yield pattern vectors representative of red, green and blue (RGB) color component distributions and hue, saturation and brightness (HSB) texture parameters. The techniques were applied to a sandy ore deposit containing three lithotypes. Geostatistical analysis indicated that the data used to characterize the lithotypes were reliable. The correct recognition of the lithotypes was carried out using a multibarycenter classification algorithm. Such in situ image-analysis procedures provide a means for selecting the ore to be mined, selecting the proper ore-processing method and determining the appropriate blend to he processed. This can be done either before or during mining.

Jan 1, 2000

By Ning Liu, Di Yin, Xuming Wang, Yongqiang Lu, Jan D. Miller

Air-sparged hydrocyclone (ASH) flotation technology has been evaluated for phosphate recovery from the central Florida phosphate deposits. As expected, it was demonstrated in pilot-plant tests that the ASH system has a specific capacity about 50-100 times higher than that of a traditional flotation cell. In the case of fatty acid flotation, single-stage ASH flotation produced a recovery of 75-77% in a rougher concentrate containing 24% P2O5 In reverse flotation with amine, the single- stage ASH system produced a phosphate recovery of 98% in a cleaner concentrate containing 31% P2O5. These results are comparable with those obtained at plant operations in the Florida phosphate industry. Based on these pilot-plant results, the effects of process variables are discussed in terms of separation efficiency. Subsequently, a 6-inch ASH system was fabricated and tested in a central Florida phosphate plant for reverse flotation in the amine flotation circuit. The high capacity of the ASH system was again demonstrated for the 6-inch ASH system. A single-stage phosphate recovery of 91% was achieved with a concentrate grade of 30% P205. During plant tests, it was established that porous tube plugging, the most significant engineering problem identified, was due to the poor quality of the plant water. Possible solutions to this problem are discussed.

Jan 1, 1999

By Edwin A. Harre, John J. Mortvedt

Plants obtain nutrients from both air and soil. They absorb carbon dioxide mainly from the air, although some carbon dioxide may be dissolved in soil water which is absorbed by plant roots. Carbon dioxide, a gaseous form of carbon and oxygen, supplies the carbon which usually makes up 50% or more of plant structure. Growing plants use water more than any other biological substance. Plant nutrients dissolve in soil water and enter the plant via root absorption. Water is then given off into the air as the plant breathes or transpires. Water also supplies hydrogen and oxygen to plants. Plant roots absorb nutrient cations or anions by contact exchange with soil clay particles. Inorganic or mineral nutrients essential to plants are supplied through the soil. Inorganic or mineral composition of plants usually is less than 5% of their weight. In most crop-growing areas, much of this nutrition is inadequately supplied from soil reserves and must be provided by fertilizers. The role of the fertilizer industry is to provide economical, efficient, good quality fertilizers to improve or maintain soil productivity for optimum crop production. The essential plant nutrients other than carbon, hydrogen, and oxygen which often must be added to soils or plants are categorized as primary nutrients (nitrogen, phosphorus, and potassium), secondary nutrients (calcium, magnesium, and sulfur), and micronutrients (boron, chlorine, copper iron, manganese, molybdenum, and zinc). These classifications are based on quantity of nutrients utilized by plants and do not imply their function or degree of necessity. One point of major significance to the fertilizer industry is that not all fertilizer minerals contain the plant nutrients in a chemical form available to the plant. A product which may be considered a fertilizer mineral may require substantial processing or treatment before it becomes useful as a nutrient source or fertilizer.

Jan 1, 1994

By Qing Wang, Xiaochuan Xu, Jianping Liu, Xiaowei Gu, Qingyu Zhu

"The ecological costs related to the various optimized production schemes were calculated based on the designed ultimate pit. Moreover, the influence of the ecological costs on the selection of production schemes was discussed. In one designed pit, a series of geologically optimum pushbacks with sufficiently small increment were produced using the floating cone method founded on the principle of the highest metal content. Then all the pushbacks were reordered by the dynamic network diagram. The production scheme with the maximum NPV route was considered as the optimum one. The ecological impacts produced by mining were quantified and the ecological cost calculation models, which contain the direct eco-value loss, the indirect eco-value loss, the eco-restoration cost and the carbon emission cost were proposed. In one big open pit mine case, various production schemes were optimized and the one with maximum NPV was selected without taking into account the eco-costs. The scheme with the maximum comprehensive profit was obtained by calculating the eco-cost of each scheme. The results showed that the best scheme considered with the eco-cost was not the scheme with the maximum NPV. Therefore, the eco-cost presents the effect on the selection of the best production scheme.Introduction Optimizing production scheme is to determine the mining quantities of ore and rock, the pushing position of stope each year, and maximize the NPV of mine. In the theory, production scheming optimization has gone through trial and error (Pana and Carlson 1966), linear programming method (Johnson 1968), mixed integer programming (Gershon 1983), integer mapping (Kim and Cai 1990), dynamic programming et al (Gu et al 2014). In recent years, the study on production scheduling optimization has been focused on two aspects. On the one hand, the study is to solve the investment risk caused by the uncertainties of economic and geological environment (Ramazan and Dimitrakopoulos 2013, Marcotte and Caron 2010, Lamghari and Dimitrakopoulos 2012, Godoy and Dimitrakopoulos 2004, Benndorf and Shishvan 2014). On the other hand, the emphasis of the study was on reducing the problems for the optimization algorithm, to make it more efficient and practical (Cullenbine et al 2011, Shishvan and Sattarvand 2015, Askari-Nasab et al 2011, Nasab et al 2010). However, different production schemes cause different damage of mine land and pollutant emission, thus triggering environment problem. With the improvement of people’s consciousness of environment protection, the environmental issue of mining has been attracting more and more attention."

Jan 1, 2017

By G. Meiers, M. O’Kane

Dry cover systems as a closure option for management and decommissioning of waste rock and tailings is a common prevention and control technique used at numerous sites around the world. Numerous site-specific factors control the long-term performance of dry cover systems. Site-specific climate conditions are one of the key factors to consider when determining the objectives of a dry cover system because these conditions will significantly influence long-term performance. There are advantages and disadvantages of characterizing the site on an annual basis as generally a “dry” site (annual potential evaporation greatly exceeds annual precipitation), or generally a “wet” site (annual precipitation meets or exceeds annual potential evaporation). The field performance monitoring data and discussion presented herein illustrates the caution that is required when using these “annual” criteria for characterizing site climate conditions. Numerous sites exist where precipitation exceeds potential evaporation on an annual basis; however, the site typically experiences hot, dry summer months where evaporation greatly exceeds rainfall. These dry summer conditions have a strong influence on long-term performance. In contrast, sites where potential evaporation exceeds precipitation on annual basis, typically experience periods of the year when a moisture surplus occurs, which also impacts on long-term performance. This paper uses soil-atmosphere cover design modelling and field performance monitoring from sites in Canada, Australia, and the United States to demonstrate the importance of considering site-specific climate conditions when predicting long-term cover system performance.

Jan 1, 2003

By Charles E. Melbye

INTRODUCTION In a discussion of South American exploration, it is difficult to know how much area to cover, as there has been such intense exploration for many years in all of the South American countries. Therefore, I have decided to discuss only Argentina, Bolivia and Peru in this paper, since I am most familiar with these three countries. This familiarity has been gained during my last 12 years of nearly continual exploration and mine development. Furthermore, these three countries form a contiguous block straddling the Andes Mountain chain for 2,200 miles in length N-S. Although Chile is part of this block, I excluded that country because it has had the longest recent history in South American exploration, and it is now in a mature stage where new important mines are being placed in production every year. Exploration must progress a lot for the other three countries to attain the stature of Chile. However, major exploration successes such as Yavacocha and Pieriva in Peru, Kori Khollu in Bolivia and Bajo Alumbrera, Agua Rica and Cerro Vanguardia in Argentina certainly indicates that these countries are rapidly accelerating in exploration successes and the resulting new mine developments. Also, by concentrating on three countries, I have avoided making this paper too lengthy. This paper will cover activities of both junior and senior mining companies, both of whom are making significant contributions to exploration. The junior companies often make the initial discovery, develop it further and then bring in a major company when large capital is required. Since most exploration is for gold and copper or combinations of these, most descriptions will cover these types. However, there are significant new exploration successes for zinc and for silver-lead-zinc, and they will be covered, as well. After descriptions of the various properties, there is included a discussion of the governmental policies of Argentina, Bolivia and Peru, as to how they are affecting exploration activities and budgets. Some of these problems could have a major negative affect on the future exploration plans of many companies. I have intended to cover what I think are significant exploration developments in each country, and if a company project is omitted, there was no intention to slight anyone. Since exploration results change monthly, there could be

Jan 1, 1998

By N. Finkelstein, C. G. Palagi, S. S. Stillar

The C. E. Weed concentrator treats 51,000 tons per day of 0.5% to 0.7% copper ore received from the Berkeley Pit, the Continental East Pit and the Butte underground mines. Improved operating techniques and conversion from semi-autogenous secondary grinding to ball milling have increased tonnage from an original design of 42,000 tpd. Separate treatment of sands and slimes, with recovery of soluble cop- per from the slimes, has increased total copper recovery. Concentrator tailings are pumped 600 vertical feet and 20,000 horizontal feet for disposal.

Jan 1, 1976