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By Rosa H. Harris

The world's largest gold dump leach operation, Minera Yanacocha S.A., has installed community assistance programs in Peru concerned with health, education, electrification, agricultural assistance and road improvements. The programs are conducted in a joint venture fashion in association with various organizations.

Jan 1, 1998

The 1996 Arizona Conference was held in Tucson on Dec. 8 and 9. Attendance was 648, a 12% increase from the 1995 conference. The annual conference is organized by the Arizona Conference Board of Directors, representing SME sections from throughout Arizona and adjacent areas. In addition to those representing mining and processing operations in the Arizona region, the meeting was well attended by interested parties from throughout North America. These included vendors, consultants, academia, research organizations and corporate management. The technical program highlighted the meeting. It consisted of a keynote address and morning and afternoon technical sessions. In the technical sessions, 23 papers were presented by the mining, hydrometallurgical, smelting, geology and mineral-processing divisions. The conference was then capped by a banquet that included a talk by a noted economist. Keynote address The program was kicked off by a keynote address titled "Forecasting for the 105th Congress," by Rep. John Shadegg (R-AZ). He was elected to Arizona's Fourth Congressional District in 1994. Shadegg serves on the House Budget Committee, the Resources Committee and the watchdog Government Reform Committee. He stressed the familiar conservative positions of reducing government spending, balancing the budget and states rights. As a member of the House Resources Committee, Shadegg stated his support for the mining industry. Technical sessions Mining division. Two of the five presentations described developments at two Arizona mining operations. T.J. Swendseid of Phelps Dodge presented a paper titled "New developments at Morenci" and P. Garretson of BHP presented a paper titled "Startup of the Robinson Project." Morenci continues to expand its operation and recently broke records for production. Other developments at Morenci included the completion of a 600-m (2,000-ft) drainage tunnel and stockpile rehandling. In addition, Phelps Dodge moved Morenci's crusher plant. It was completely disassembled and reassembled in just eight days. Another interesting presentation was "Predictive maintenance techniques for large electric shovels at Cyprus Sierrita," presented by T. Ritzel of Cyprus Amax. The presentation described high-technology methods for predicting maintenance problems. These methods included vibration analysis, ultrasonic detection, infrared thermography, electrical measurements and tribology (the science of lubricant evaluation). The benefits of these techniques are reduced downtime of the equipment, as was demonstrated in case studies at the mine. The other presentations were "Introduction to NOSA 5-star safety program," by R. McKinnon, BHP Copper North America, and "A new design guideline for mine sealing," by K. Fuenkajorn, Rock Engineering International. Hydrometallurgical division. The hydrometallurgical session consisted of five papers. These included a presentation titled "Recovery of gold and silver using guanidine-based extractants," by M. Vining of Henkel Corp., Tucson, AZ. In this presentation, guanidine-based extractants LIX-79 and AURIX resin were introduced. LIX-79 was shown to have applications in copper-gold and high silver ores. In ammonia-cyanide leaching, AURIX was shown to be more selective in CIL vs. RIL comparisons. Other papers in the hydrometallurgical division included "Application of cobalt in the copper industry," by J. Hawke, OMG Apex Inc.; "Series parallel conversions and production gains at Cyprus Miami Mining's dump leach and solvent extraction operation," by E. Bilson of Cyprus Amax; "Lead alloy anode corrosion at the San Manuel SXEW tankhouse," by W .M. Gort of BHP Copper and "Hydrometallurgical treatment of copper refinery slimes," by B.C. Wesstrom of Phelps Dodge. Smelting division. Three papers were presented in the smelting division session. These included updates and reports on improvements at the Hayden, Hidalgo and BHP San Manuel smelters. For example, W.A. Dutton of Phelps Dodge presented "Recent improvements at the Hidalgo Smelter." These changes were aimed at reducing environmental emissions and increasing production. They included modifications to the fugitive-gas collection system to reduce particulate emissions, rubber lining the acid plant scrubbers to reduce corrosion and the installation of a cold lime softening system for water treatment. Equally interesting papers were presented by D. Norton of Asarco, Hayden, AZ, in a paper titled "Update of the Hayden smelter process," and by D. Jones of BHP Copper, San Manuel, AZ, in a paper titled "Update on first campaign of the BHP San Manuel Copper." Geology division. The session began with a paper that outlined the progress of an exploration project in South America. "The Pierina exploration project, Ancash Province, Peru" was presented by J.D. Lowell, Lowell Mineral Exploration, Rio Rico, AZ. Another paper was then presented on a copper deposit in Grant County, New Mexico. "Zonation of supergene copper minerals at Hanover Mountain, Grant

Jan 1, 1997

By M. Karmis

"The process of coal mining, as indeed of the mining of any stratified mineral, is inevitably followed by some degree of sinking of the superjacent strata and consequently of the surface." Royal Commission on Mining Subsidence, Second and Final Report, London, 1927. INTRODUCTION The above statement was used to describe mining subsidence in the classic report of the "Royal Commission on Mining Subsidence," published in 1927. In fact, this phenomenon has been recognized in Britain since the early fifteenth century, as revealed from court records of disputes and litigations related to property damage above mine workings (Shadbolt, 1978). The first attempts to investigate and analyze the mechanisms associated with mining subsidence, however, date back to the 1800's and were pursued by Belgian Engineers. This research effort was initiated as a result of the widespread movements and subsequent structural damage suffered by the City of Liege in the 1820's. The most notable achievement of the Belgian school of that era was he publication of Gonot's treatise "Loie de la Normal" in 1871 (Gongt, 1871).

Jan 1, 1982

By R. E. Johnson, J. E. Dutrizac, B. R. Palmer

Silver sulphide (acanthite) and lead sulphide (galena) dissolve relatively rapidly in FeCl3 media with the formation of elemental sulphur and soluble silver and lead chlorides. Parabolic kinetics are observed, and the leaching rates are controlled by the outward diffusion of the AgCl and PbCl2 reaction products through the constantly thickening elemental sulphur layer formed on the sulphide. Hence, both leaching rates are strongly dependent on those variables which affect the solubility of AgCl or PbCl2 at the reaction interface. The rates therefore increase with increasing temperature and total chloride ion concentration, but decrease in the presence of elevated concentrations of AgCl or PbCl2. By contrast, neither sulphide is significantly attacked by ferric sulphate media, even at high Eh values. Although the reasons for the refractory behaviour of Ag2S in sulphate media remain unknown, the low rate of PbS attack is attributable to the passivating layer of PbSO4 and elemental sulphur formed on the surface of the galena.

Jan 1, 1993

By W. J. Kogelmann

Roadheaders, also called Boom Miners or Boom-type Tunneling Machines have been in North America since 1968, when first introduced by Willy Kogelmann, the founder of Alpine Equipment Corp. (?Alpine?). Roadheaders were invented in Europe in the late 1940s. Machines with in-line, axial cutter heads were developed in the former Soviet Union. The British Dosco DRCL is based on the Russian PK-3 roadheader. Roadheaders with transverse ?ripper? cutter heads were invented in Hungary (1). The Austrian-made Alpine Miners of VOEST-Alpine, purchased by Sandvik AB, are based on a 1965 Hungarian license. Roadheaders are widely used in the mining and tunneling industries because they can excavate drifts, entries and tunnels with cross sections of any shape and size, can handle mixed faces, work on steep grades, and negotiate tight curves and cross-cuts. A roadheader?s only major limitation is the strength and abrasiveness of rock and minerals to be excavated. This paper covers roadheader selection criteria, improvements in reliability, attachments for flexibility (Multi-Tool Miner), and automated support systems for increased cutting time for increased shift production.

Jan 1, 2008

By E. D. Attanasi

The US mining industry finished the traumatic 1980s with a strong economic performance. Worldwide economic growth and capital spending led to tight metal markets. So, 1989 metals prices were generally higher than average 1988 prices. Financial markets' volatility resulted from US junk bond defaults, heavy US savings and loan losses and effects on the US budget deficit, higher energy prices, and the seemingly intractable problems of some debtor countries. Moreover, the events in Eastern Europe promise fundamental changes in the world economic system for the 1990s. US mining companies that survived the decade had weathered economic changes that, at one point, reduced industry employment by 40%, drove oil companies to divest or liquidate recently acquired mineral subsidiaries, and led to substantial write-offs of reserves. Canadian and other international minerals firms experienced similar industry upheavels. The forced modernization and capacity rationalization produced an internationally competitive US industry. For example, even though 1989 US copper production was 27% greater than in 1980, industry employment was less than half the 1980 level. The steel industry and other minerals industries showed similar productivity improvements.

Jan 1, 1990

By R. C. Timberlake

An understanding of the Florida Phosphate Industry, the mining practices and extraction processes and the historical development of the Industry, is essential to any consideration of reclamation. In the earliest days of the Industry, phosphate rock was produced by screening the phosphate pebble from the matrix. The waste, which consisted of overburden, clay, sand and fine phosphate, and was called "debris", was disposed of onto, either the adjacent surface area, or into mined-out pits. Since the Central Florida area was sparsely settled in those early days, there was no complaint from residents about contamination of streams or the resulting spoil piles - environmental concerns were non-existent. The development of the flotation process in the 1930's and the implementation of the flotation process in the early 1940's was a significant technological breakthrough in the Industry. This technique made possible the extraction of fine phosphate particles, and doubled the recovery of phosphate values from the matrix. However, the implementation of the flotation process produced a new waste disposal problem.

Jan 1, 1978

By Kefton H. Teague

Olivine was first described and named by Warner in 1790. It is an olive green to greenish gray colored magnesium-iron silicate containing a mixture, in solid solution, of fosterite (Mg2SiO4) and fayalite (Fe2SiO4). Ratios between fosterite and fayalite in olivine are somewhat variable, but in general olivine contains at least 85% fosterite. Specific gravity is variable also, depending on the ratios of fosterite to fayalite. As a rule it is in the 3.2 - 3.4 range. All commercial olivine is obtained from the rock dunite, the most basic member of the peridotite group. Dunites, in addition to being composed primarily of olivine, generally contain assessory pyroxenes and spinels (chromite and magnetite). Dunites', when altered by hydrothermal solutions or metamorphism, often contain alteration minerals such as talc, serpentine, chlorite, vermiculite and amphiboles. In the 1930's and 40's considerable research was conducted on olivine for use as a refractory, plant food raw material, magnesium source for metal, and a source for magnesium chemicals. This research met with only limited success.

Jan 1, 1977

By A. C. Smith

Although it is only utilized in a few U.S. longwall mines, a bleederless ventilation system can be an effective spontaneous combustion control method in mines with a demonstrated history of spontaneous combustion. In order to provide insights for the optimization of bleederless ventilation systems for U. S. underground coal mines, a computational fluid dynamics (CFD) study was conducted to model the spontaneous heating in longwall gob areas with a bleederless ventilation system. A single longwall panel with a bleederless ventilation system was simulated, and typical ventilation data for a longwall mine was used in the simulations. The permeability and porosity profiles for the longwall gob were estimated using a geotechnical model and were used as inputs for the CFD modeling. The effects of gob permeability and resistance of the collapsed entries on the spontaneous heating were studied. The effectiveness of nitrogen injection to prevent spontaneous heating in the gob was also examined. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Jan 1, 2008

By Mary C. Jennings, Peter F. Marcus

This paper examines the dynamics of aluminum consumption (all products), scrap recovery and primary aluminum capacity for the Western World through 1995, with particular emphasis on the U.S. aluminum industry. The relationship between the prices of ingot, sheet and extruded products is also explored.

Jan 1, 1986

By Edward F. Fries

Computerized, real -time monitoring had its beginning in the U.S. coal industry in the early 1970's. Over the last 10 years, developments in technology have made systems available that are capable of monitoring and controlling many mine parameters that can increase safety and production. However, situations currently exist where computerized monitoring systems are not being utilized to their fullest capability. They produce reams of printed output that are not sorted in a useful format, and human operators are not able to react fast enough in emergency situations tn tile large amount of information that the systems generate. A solution is the application of an expert system as the interface with real-time monitoring. An expert system would use an extensive knowledge base and human-type reasoning ability to make decisions on optimum strategies. Expert systems have been applied successfully to problems in other industries, and could provide significant benefits to mine information management systems. The use of an expert system with real-time mine monitoring is discussed in this paper.

Jan 1, 1986

By J. P. Fitzgerald

This paper is an accumulation of information on the geology, mineralogy and mining of the Hectorite clay deposit owned by NL Chemicals (U.S.A.), Inc. The mine is located in San Bernardino County, California approximately 35 miles east of Barstow and 1-1/2 miles south of U.S. Highway 40. The region is known as the Mojave Block which is a region bound by the San Andreas fault zone to the southeast and the Garlock fault zone to the North. The faults of both zones are active, vertical faults along which movements are mainly horizontal. Most of the faults within the Mojave Block are high angle faults which trend northwest. They are considered part of the San Andreas fault system and are a result of the right- lateral movement characteristic of this system. The east-trending faults are also high angle faults, along which movement has displaced rock units vertically. Manix fault is the only mapped fault that shows evidence of left slip which is characteristic of the Garlock sys tem to the North.

Jan 1, 1986

By Raymond W. Peterson

The practice of Countertrade and all of its variations has increased dramatically during the last five years in great part due to the worsening world economic situation and the Third World's increasing debt problems. Conventional wisdom has held that the goods finding their way into countertrade will tend to be manufactured goods of ever increasing value added. It is my contention that this has not been the case. The continued depression of most metals and minerals prices has conspired to keep a great number of metals and raw materials in the forefront of countertrade negotiations. The concept that if a country needs hard currency it will simply sell metals into world markets for cash has been significantly modified by countertrade which encourages subsidies for raw materials which are in turn funded by higher prices for the manufactured goods which the country must import. Countertrade is a term that is relatively new to most of us who have been involved in the international trade of metals and minerals, but it is one that we will continue to hear more of in the future. Countertrade as it is generally known today had its beginnings after the Second World War in Eastern Europe. As the shattered economies of Europe struggled to right themselves, a "cashless" system of trade developed. This system included such ancient concepts as barter as well as more modern ones like bilateral clearing agreements. For over 30 years countertrade was confined mainly to the COMECON nations and their various trade protocols with Third World nations. If metals and minerals were involved, there was little disruption of world markets by such examples as Cuba shipping ferronickel and sugar cane to the U.S.S.R. for a host of manufactured goods and oil. As the world's economy began to slow in the late 70's and the debt crisis began in earnest in the early 801s, this all began to change. As more and more nations which had previously been almost totally dependent upon their mineral wealth over-extended themselves in an attempt to industralize, they concurrently found their income from minerals falling, due to the decreased demand and subsequently lower prices available in the marketplace. At first these nations attempted to balance their payments by promoting the sales of their high value-added manufactured goods. We have all heard numerous examples of U.S. companies going to sell their high technology products in Rumania or Yugoslavia and being confronted with counterpurchase requirements for machine tools, shoes or drill bits. When faced with these demands, a number of companies chose not to sell into those markets while others merrily signed up the obligations without much intent to carry them out. The Performance Bonds required were generally minimal, especially when considered in light of the high margin inherent in high tech items; and the penalty clauses were equally small or nonexistent. A third group of companies actually tried to buy the machine tools or drill bits either for their own internal use or resale but found that due to poor quality and high prices, they were faced with a difficult if not impossible task. This is not to say that no one was able to fulfill a countertrade requirement, but the success ratio on these transactions was incredibly low. This was one of the major contributing factors to the reputation that countertrade has gained as a discipline ... "that it is mostly talk and very little action." As this situation slowly evolved, both the countries imposing the countertrade obligation and the exporters assuming the obligation began to realize that something

Jan 1, 1986

By P. A. S. Manning

Eastern Jamaica consists predominantly of non-carbonate rocks reaching elevations of over 2200 m. The area is drained by a well established river network which supplies close to 30% of the sand and gravel used by the building and construction sector. Present high extraction rates and slow rates of replenishment will result in early exhaustion of this source of aggregate. A number of volcanic and carbonate rocks are being examined as a possible source of high quality aggregate which meet the requirements for all types of construction. Preliminary evaluations show a dacitic deposit to be the most suitable source for aggregate use.

Jan 1, 1998

By Donald C. Moore

Asamera Minerals Cannan Mine has been producing a 170 g gold/tonne (5 oz gold/ton) siliciaus flotation concentrate since July 1985. Flotation concentrate is shipped to a smelter for gold recovery. Numerous processes have been investigated to economically produce bullion on site. This paper describes the laboratory and pilot plant test results of a bacterial assisted oxidation of the refractory minerals. Economic comparisons with autoclaving and roasting processes are included.

Jan 1, 1989

By A. Bascetin, A. Nieto

One of the most difficult problems in mining operation is how to determine optimum cutoff grades of ores at different periods over the lifespan of the mine that will maximize the net present value (NPV) of the mine. Cutoff grade optimization maximizes the NPV of a project subject to capacity constraints in the mine, mill and the market.. This paper describes the determination of a cutoff grade strategy based on K. Lane’s algorithm adding an iterative optimization factor calculated for every year during the live of the mine to maximize the project’s NPV. The introduced algorithm is a windows based program developed at Virginia Tech which coded in visual-basic within a spreadsheet environment (Excel). The resulting cut-off windows based program is a user-friendly tool which calculates interactively different mining cutoff grade scenarios. The benefits of the methodology are demonstrated using a hypothetical case study. The authors have observed an improvement of the total NPV using this iterative approach using a year by year optimization factor.

Jan 1, 2007

By L. S. Harris

The application of briquetting in various chemical, mineral, mining and metallurgical processes has been rapidly increasing in the past two decades. This is, in part, due to the development of new, more economical and higher performance briquetting equipment. Some of these developments, which have reduced the operating and maintenance costs,, include anti-friction bearings, hydraulically applied pressure enclosed and sealed gearing and bearings, tapered predensification feed screws, water cooling and materials of construction capable of operating at temperatures up to 18000F, and control systems capable of maintaining optimum briquette quality control. The briquets can be formed into almost any desired size and shape, To date, with present rotary briquetting presses in the 25 to 500 ton force range, briquets from 1/4" to 6" length are presently being used, some of which are illustrated in Figure No. 1. In force fed rotary briquet machines, these shapes are produced by feeding the material in between a pair of counter rotating rolls, as illustrated in Figure No. 2. The rolls have forming dies indented into their circumferential surface, as illustrated in Figure No. 3.

Jan 1, 1973

By A. V. Castelli

The provinces of Guangxi, Guizhou, Hubei (and most recently Fujian) were the prime exporters of barite during this period. Guangdong and Shandong were exporters too but not major participants. These are all primarily agricultural areas so there existed a sufficient labor force willing to work in the mines to supplement their income from farming. During the early years, barite export pushed the existing transportation systems in these provinces to operational capacity. The mines from which this barite is extracted are located about 250 to 1,400 kilometers from the sea ports. Transportation of the ore from the mines to the ports follows a net-work that includes trucking to various rail-heads where it is then shipped via freight trains to ports for loading into seagoing vessels. in some instances, the barite travels by truck or train to the Yangtze River where it is then barged to an ocean port.

Jan 1, 1990

By D. V. Professor Keller

The production of premium coal-based fuels (<3% ash) and ultra clean coals (<1% ash) using the process of selective agglomeration requires proper selection of raw coal, rough preparation procedures, milling equipment, product coal size distribution, water purity, agglomerants, agglomeration equipment and operational procedures. Each of the variables can contribute a small fraction to the impurity load in the product coal or limit the ability of the process to separate mineral matter-free coal. Each of the variables and their importance will be examined from data produced at the bench by batch and continuous agglomeratons as well as the results from pilot plant and tonnage production units. The results are discussed which have indicated that some standard commercial coals can be produced with ash contents as low as 0.2 % ash (batch/bench) and several tonnage lots of 0.6% ash in as 200 lb/hr pilot plant. In most cases iron pyrite released from the coal matrix and with proper pH control is rejected from the product coal agglomerates.

Jan 1, 1995

By J. A. McKeown, B. M. Sanders, A. Dadgar, R. H. Sergent

This paper describes the leaching of gold with Geobrom® 3400 from a very rich (6.2 kg/tonne) black sand concentrate and its subsequent recovery by ion exchange resins and solvent extraction. The dissolution of gold from black sand ranged from 94 to 96%. Gold loadings and recoveries of nearly 100% were achieved by both ion exchange and solvent extraction methods. The kinetics and equilibrium of loading gold onto ion exchange resins and its elution from the resin were studied. The commercial ion exchange resins PAZ®- 4, DOVEX®- 21K, and Amberlite® XAD- 7, and Great Lakes Chemical experimental GLR-30 were evaluated in this work. Diethylene glycol dibutyl ether was used in all the solvent extraction work for gold recovery from Geobrom leach solution. The consumption of Geobrom was about 130 kg per tonne of the concentrate processed. Therefore, the cost of lixiviant to extract 3.11 x l0-2 kg of gold from the black sand was only about $1.00. Based on the electrochemical regeneration of bromine, the economics of bromine process vs. cyanidation were investigated.

Jan 1, 1990