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By B. Dabrowski, J. D. Miller, D. Halbe, J. Hupka

An air-sparged hydrocyclone (ASH) mobile system was evaluated for continuous stripping and recovery of cyanide (the AVR process) from process water at a gold plant site. The ASH unit performed exceptionally well as an absorber. HCN was removed from the gas phase in a single one second pass with an efficiency exceeding 99%. HCN concentration in the discharged gas phase was lower than 10 ppm, which provided for a safe working environment. The stripping efficiency, controlled by the Henry’s Law constant, exceeded 40% in one pass.

Jan 1, 2004

By O. A. Bascur

The problem of setting the proper control objectives and/or having several objectives to be met in the implementation of grinding control strategies can be resolved. The design and implementation of a distributed control system for safe operation of a grinding circuit while maximizing profit is presented. An optimal recovery through- put target for a desired grind is accomplished by advanced control strategies at the DCS level. A mill load constraint control technique provides stable operation with a substantial increase in throughput, while the desired grind index is maintained by an inferential grind control technique without using a particle size analyzer. The integration of crushing/grinding and flotation in the overall design was the key to the success of the project. This synergistic effect was obtained by implementing a computer plant management system in the concentrator. The overall/philosophy was to keep the implementation simple while using new technology creatively.

Jan 1, 1991

By Ronald F. Ayers

The study upon which this paper is based was completed by Battelle's Columbus Laboratories for the U.S. Army Corps of Engineers in 1974. It is but part of an overall effort by the Corps to evaluate the costs and benefits to the nation of waterway improvements. This study is primarily concerned with future coal markets for production from those counties near the Wabash River in the heart of the Eastern Interior Province. An objective here is to consider a most pessimistic energy (and hence, coal) demand for planning purposes.

Jan 1, 1976

By S. J. Czehura

The Butte quartz monzonite is the host rock for early porphyry copper style mineralization and subsequent mesothermal-epithermal, enargite-gold style veining that transects the district. The east-west Anaconda system veins: including the Emma, Anaconda-Original, Syndicate, Badger-State, and Alice-Rainbow veins, each with strike lengths of over 12,000 feet and vertical continuity in excess of 4,500 feet, along with mining widths from 5 to 50 feet, are unique to Butte. The incredible dimensions and tenor of these veins have yet to be surpassed and Butte is still touted as being the “Richest Hill on Earth.” The Anaconda Company was formed in 1895 to develop underground copper reserves in the district and eventually consolidated all operations under one company. Production from underground mining continued through the mid-1970’s. Open pit mining in the Berkeley pit began in 1955 with the extraction of supergene ores, along with the remnants of deeper horsetail zones inaccessible to the underground mines. Operations in the Berkeley pit were suspended in mid-1982 because of the rejection of high arsenic, copper concentrates at major smelting facilities throughout the world. Bulk mining of porphyry style mineralization in the Continental pit began in January 1980 to supplement copper production while stripping “C” pushback in the Berkeley pit. The Anaconda Smelter closed in September 1980. A molybdenum circuit was added to the Butte Concentrator in 1981 and mining continued in the Continental pit to produce copper and molybdenum concentrates. A blend of Berkeley and Continental ores were processed to dilute penalty metals in the final concentrates marketed to toll smelters. All mining operations ceased mid-1983 when Anaconda closed the Continental pit and offered the property for sale. Montana Resources reopened the Continental pit in June 1986 to produce copper and molybdenum concentrates. Operations were suspended mid-2000, because of exorbitantly high power prices, but resumed in November 2003 with rising metal prices. Bulk open pit mining of the early porphyry style mineralization has sustained production over the past twenty years and mining is expected to continue in the Continental pit with favorable prices. Future mining will eventually develop a 500 million-ton geologic resource incorporated in a supergene enrichment blanket situated between the Berkeley pit and the Continental pit. Grades in this enrichment blanket range in the neighborhood of 0.5% copper.

Jan 1, 2006

The only good news in the exploration sector in 1982-a year plagued by low metal prices and weak demand-was precious metals. Gold in particular remained in the forefront, as it has for at least the past three years. The reason for this is partially due to gold's seeming resilience to conventional supply side factors-such as new production-that normally influence many other metals. Also, with projected production costs of about $6.40-$9.65/g ($200¬$300/oz), modest deposits with average grades can offer an early return on capital investment and good profit potential. Keeping escalating capital costs for new mining ventures within reason has shifted gold exploration efforts in recent years. Many mining companies are seeking relatively low grade, modest tonnage, near-surface gold mineralization. This, of course, leads to lower development costs using open-pit mining methods. Recent refinements in the carbon-in-pulp recovery process also has enhanced the economics of such deposits. Slumping economic conditions certainly played a key role in shaping exploration activity last year. Nearly every major mineral-producing state recorded exploration slowdowns. In Alaska, for example, development expenditures approached the level of exploration spending for the first time in the state's history. This not only reflects major companies' decisions to move toward production but also the economic slowdown. The worldwide recession stopped Nevada's exploration and mining boom "dead in its tracks," said John Schilling, state geologist. The year was one of layoffs and closings for the state's mines and exploration offices, he reported. Similar trends were noted in most other states, especially in the West and Southwest. In the Pacific Northwest, however, exploration appeared to continue at a relatively good pace considering the metals market. In the mining geophysical community, recent advances in telecommunications and microprocessor technology are continuing to provide a positive impact. Many geophysicists have begun using satellite digital communication links to access computer systems from remote sites where using a microcomputer would be difficult. There were also major contributions made in exploration geochemistry last year. Highlights include progress in formulating mineral deposit models, geochemical exploration in glaciated and arid environments, and publication of many informative books. The following state-by-state summary and articles on geophysics and geochemistry provides a detailed view of exploration events throughout the US in 1982.

Jan 5, 1983

By R. J. Pruett, P. I. Prescott

Ground calcium carbonate (GCC) is used in the paper, plastics, paint, rubber and caulks and sealants industries. The favorable properties of GCC include high whiteness and brightness, low hardness and outstanding rheology in water systems. The quality of calcitic GCC ores, which includes chalk, limestone and marble, is dependent on calcite purity and the nature and quantity of the impurity minerals. Wet and dry grinding are used in the processing of GCC. Ore processed by optical sorting, flotation and/or particle-size classification has higher brightness and lower abrasion characteristics. GCC markets are a function of the product's properties, purity and cost.

Jan 1, 1997

By R. M. Wheeler

For years the blasting industry has recognized eight milliseconds as the minimum delay time interval required between charges in order for them to be considered to fire independently of each other. However, computer analyses of seismic recordings made of several surface mine blasts reveals that this time interval may not always be sufficient for adequate vibration separation to occur. In some situations a combination of short delay periods and low frequency vibrations can result in waveform reinforcement. Various analyses of seismic recordings obtained from single hole detonations can be used to predict delay intervals that may enhance or reduce blast vibration effects.

Jan 1, 1987

The public relations problems of users of explosives have greatly increased within the past few years. One reason is that explosives and blasting agents are being consumed in increasing quantities. The principal reason, however, is that more people have become physically affected by blasting. Mines, quarries, and construction sites that were formerly in relatively remote locations now find themselves near congested areas. New express traffic ways being constructed to connect the suburbs with downtown areas are being built through the middle of long-established business and residential neighborhoods. The public becomes aware of blasting by two physical sensations-vibration and noise. Vibrations are usually so slight as to be negligible, and in most cases the only sensation noted is noise. The reduction of vibrations to this low level has been primarily achieved by the use of blasting practices and explosive products recommended by vibration engineers based on seismograph recordings. Unfortunately, very little scientific attention was given to the accompanying physical sensation-noise.

Jan 1, 1962

By W. DR. Fritz

Technical progress depends on strategic objectives and a concept showing how to benefit from the effects of novel techniques in an innovation process and how to implement them creatively in harmony with manpower capabilities. With the invention of prime movers, it was initially power engineering which dominated the development of industrial history before it was replaced by production techniques resulting from the more widespread use of machines. With the advances in the field of data processing and with the introduction of novel communication techniques, it is information technology- which today is having an ever increasing impact on technological progress. The main objectives of information technology in this context are a positive influence on the ?time? factor as well as the provision of tools to handle the complexity governing many operational processes through a concentration of information for the decision-making process. The German hardcoal industry became aware of the chances inherent in these new technological possibilities for the optimization of operational sequences and of decision-making and planning processes as a potential for success at an early stage and it has worked out a purposeful concept for their implementation.

Jan 1, 1992

By L. Piga, P. Cipriani, F. Pochetti

High-temperature roasting of alunite in the presence of K2CO3 gives rise to a reaction that results in up to an 80% recovery of its potassium content as K2SO4 by leaching of the roasted mixture. K2SO4 is also generated from the reaction between the added K2CO3 and the SO3 driven off during roasting of the alunite. This limits the environmental and corrosive problems involved in the thermal treatment of this mineral. A solid residue containing mainly aluminum oxide is also obtained. This could be used as raw material for the production of aluminum, as the use of K2CO3 does not introduce different cations than are in the ore. A statistical study was performed on the factors assumed to affect the recovery of potassium, namely, roasting temperature, K2CO3- alunite stoichiometric ratio and leaching temperature.

Jan 1, 2000

By J. K. Horbaczewski

The reclamation of an open dragline pit (Pond A3P-2) at the Gibbons Creek lignite mine in east-central Texas required neutralization of acid mine pit water. At the start of treatment with hydrated lime (Ca(OH)2) on March 28, 2000, the pond had partially filled with 913,000 m3 (740 acre ft) of pH 4.9 water. Another 666,600 m3 (540 acre ft) of pH 3.3 water was pumped in from an adjacent pit (PitA3P- 1). By the end of the project (July 5, 2000), a combined volume of 1,579,000m3(1,280ac-ft or 417milliongal) in PondA3P-2 had been successfully treated to pH 8.2 with 431 t (475 st) of lime. This was two to three times more neutralizer than laboratory trials and detailed chemical titration had predicted. The main reasons for the difference are thought to be the inadequate representation in a laboratory setting of some of the chemical reactions that occurred in the field, including incomplete mixing of reactants, reactions with clay minerals in the pit walls, the kinetics of biologically-mediated reactions and the kinetics of aluminum oxyhydroxide polymerization (aging).

Jan 1, 2002

By Alan G. Mayton, Jon C. Volkwein

The U.S. Department of the Interior, Bureau of Mines, in cooperation with an American firm, has been contributing toward the creation of a new highwall mining system for extracting coal in active, unreclaimed contour strip mines in the United States. The prototype system features the computer-based, remote control, video operation of a thin-seam continuous miner. Haulage is accomplished remotely also with a 76-m (250-ft) long multiple-unit continuous haulage (MUCH) conveyor system on rubber-tire vehicles. One aspect of this multi-faceted effort has been to design a ventilation system for removing dust generated at the face during the extraction process. The remote mining system eliminates the need for personnel in the mined workings. Ventilation is required to remove visible dust from the area inby two video cameras. These cameras are located approximately 6 m (20 ft) from the face, one on either side of a modified Jeffrey 102HP continuous miner. Removing the dust from this area provides the remote operator with constant visual monitoring of coal extraction at the face and thus, insures the effective operation of the mining system. A ventilation system was designed for use in a mine opening with a maximum cross-sectional area of roughly 4 sq m (44 sq ft) excluding the mining machinery. This paper describes the ventilation system and discusses how it was developed in view of the constraints imposed by the mining equipment, mining conditions, and the extraction process.

Jan 1, 1989

By S. Chander

Neutralization of acidity by addition of alkaline materials is a commonly used method to treat acid mine drainage. However, this procedure requires large amounts of reagents based on acid-base accounting. The potential use of organic additives in preventing or ameliorating acid mine drainage was investigated in this research. The tests were conducted in weathering columns using refuse samples from a coal cleaning plant. Both cationic and anionic compounds were tested. For a comparison, tests were made in the presence of limestone and lime. The results show that some of the reagents substantially retarded the rate of oxidation whereas others even enhanced it. The suppression of the rate of pyrite oxidation was ascribed to surface chelation. Formation of surface compounds prevented the pyrite particles from further oxidation. Such a treatment required only small quantities of reagents since the reaction was confined to the surface.

Jan 1, 1992

By Christopher J. Bise

The potential of the coal reserves in the western United States for meeting future energy needs has been recognized for quite some time. However, two of the major constraints which have tended to limit the development of these reserves which can only be deep-mined are the great thicknesses of the coal seams encountered and their high pitch. Although new mining methods may need to be developed to recover these reserves, at least in the short- term the industry has to incorporate presently available equipment which were not originally designed for thick-seam mining. The purpose of this paper is to present an analysis of the various equipment that are in use today and their possible application to thick-seam mining. The paper also addresses the various ground control and safety considerations that are unique to thick-seam extraction.

Jan 1, 1981

By D. D. Young

During the 1970's a number of covered storage facilities were constructed in North America to store and handle large quantities of bulk, solid materials. This trend, away from outdoor storage piles, will probably continue at a stronger pace in the 1980's. This paper attempts to answer some of the questions often raised about the economics of large covered storage facilities. The paper is in four parts: 1. Why Build a Storage Facility? 2. 2. Common Components of Storage Systems With Details of Six Storage Facilities 3. Results of a Study for 50,000 Mg Clinker Storage 4. Guidelines for Conducting a Study to Select a Storage System.

Jan 1, 1980

By James R. Arnold, Timothy D. Arnold

The mathematical rigor of the collegiate engineering experience prepares an engineer well for the technical aspects of his or her career. However, as that engineer progresses in the industry, how well does he or she do as a manager? The exacting, detailed, and complete problem-solving process that engineers are trained to use sometimes conflicts with the nimble, rapid decision-making process required in the dynamic world of business. This paper discusses the topic of "engineers as managers.”It will investigate the personality traits of engineers relative to the traits of successful managers, and provide specific details about how well engineers have done in the field of management.

Jan 1, 2001

By Franc Runovc

The service hoisting plant in the mining transportation is an installation serving for the vertical transport of material and persons. An adequate mathematical model is presented for simple evaluation of the project parameters where different plant designs and the ways of transport are take into consideration. The technical and economical optimization procedure is added to the basic mathematical model of the project. This approach enables on one hand the optimization of the reconstruction of the multi-purpose hoisting plants in order to suppress possible bottle necks, while on the other hand it enables the determination of such values of the parameters of the choice and of the operation that the sum of total expenses per a transport unit' becomes the lowest. The optimization procedure is designed in such a way that all numerical data of the optimum hoisting plant are printed out together with the graphical representation of dependencies of the fundamental parameters in broader optimization region.

Jan 1, 1992

By Y. Nien Wang

The Devil?s Slide portion of Highway 1 between Pacifica and Montara is often closed due to the instability of the adjacent slopes. Following many years of public input and careful evaluation of alternatives, Devil?s Slide will be by-passed via two inland tunnels, providing a safe, dependable highway between Pacifica and Montara. For the twin tunnels, each 9m diameter tube will accommodate only one traffic lane. Each tunnel tube will accommodate a 3.6 meter roadway, 0.6 meter and 2.4 meter inside and outside shoulders respectively, and 1.2 meter walkways on each side. Cross passages will connect the bores at about 120 meter intervals and jet fans will provide tunnel ventilation. The twin tunnels are approximately 1,250 meter long and 9 meter wide. Excavation will progress from south to north using tunneling techniques that rely on inherent rock strength for support known as the New Austrian Tunneling Method (NATM). Both tunnels will be excavated at the same time, one tunnel face approximately 40 meters ahead of the other. Staggering the tunnels reduces the likelihood of damage from blasting in alternate tunnels. The work schedule is 24 hours a day, 7 days a week resulting in a 24-month timetable to break through to the north portal.

Jan 1, 2008

By William A. Ribich, Hans A. Hug

INTRODUCTION Providing sufficient thrust, particularly in the proper manner, is one of the major problems of conventional hardrock drilling and tunneling machines. For instance, with tunnel boring machines, massive jacks, mechanisms, and structures are required to generate and transmit the forces to the cutting head. One pays for this massiveness both in terms of material (dollars per pound) and in the attendant difficulties of transporting and maneuvering such machinery. The effect of an efficient thrust generation method on system size is evident when one considers conventional shaft drilling equipment. Raise borers are small enough to be used underground, while conventional big hole drilling equipment requires large amounts of space, personnel, and support. Proper application of the force is another problem, even with smaller holes such as blastholes. While one can load most tricone blasthole bits to their limit with such drill rigs as the Bucyrus Erie 61R or the Gardner Denver 120D, transmitting very large forces through the relatively flexible mast and drill pipe leads to large vibrations, fatiguing of the mast structure, and impact loads on the bit. In the following, a new method of generating the required rock fragmentation force is presented. Furthermore, the force is generated and applied in such a fashion that not only can the equipment size and weight be reduced, but also the cutter and equipment life can be increased.

Jan 1, 1974

By G. D. Schena

A decision support system for the management of the mineral resources of a developing country has been derived. The system allows the evaluation of the impact of a mineral project in a developing country in the broad context of its economy. The analysis permits the assessment of the overall socio-economic consequences of mineral prospects and allows incorporation in the evaluation of issues that are broader in scope than the pure financial objectives. The system is built around the Leontief framework of economic analysis. The original input-output model, enhanced to incorporate country-specific behaviour is integrated with cost-benefit analysis and shadow pricing. The analysis leads to synthetic measures of profitability at market and shadow prices. These measures are useful to direct the mineral policy of a developing country through the exploitation of those mineral resources which are most likely to bring about economic growth and social advancement.

Jan 1, 1992