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By C E. Loayza, R M. Pinto, J G. G=mez

The Yanacocha District is located 20 km north of the city of Cajamarca, in the Northern Andean Orogenic belt of northern Peru.Gold production may have occurred as early as Incan times (Paverd, 2000), but modern exploration that began in the 1960s targeted only copper and silver. Newmont Mining Corporation, BRGM and Compa±fa de Minas Buenaventura began exploring for gold in 1983, with Newmont as operator.Initial drilling took place in 1985. By 1992 a reserve of 1.28 million ounces was reported (Teal et al, 2002).Production began at the Carachugo deposit in 1993.Current reserves are 31.7 million ounces at $US 325 per ounce at a grade of 1.03 ppm (Newmont Annual Report, 2003).The operating company, Mineral Yanacocha SRL (Newmont 51 per cent, Buenaventura 44 per cent and International Finance Corporation five per cent) produced 2.85 million ounces in 2003, making Yanacocha one of the largest gold mining operations in the world. The district is made up of a series of epithermal, high sulfidation style gold deposits and one gold-rich gravel deposit (La Quinua), aligned in a NE trend.La Quinua is not discussed in detail in this paper. The bedrock deposits are hosted in a Miocene volcanic package, the Yanacocha Volcanic Complex that also trends NE.Re gional NW striking Andean faults intersect the NE striking Trans-Andean Chicama-Yanacocha structural corridor (Turner, 1997), localising the district mineralisation. These two structural orientations dominate the district, controlling breccia and intrusion locations, and gold mineralisation. Discontinuous EW oriented fracture zones are interpreted as extensional and locally are important in controlling gold mineralisation.

Jan 1, 2004

By T. W. Lippert

In these opening remarks, I will endeavor to give a background of continuous casting of metals. Only passing attention will be given to the different processes to be described by the authors whose papers are on the program, as they are far more familiar than I am with their subject matter. Suffice to say that over the past several years the brass, copper, aluminum and magnesium industries have shifted practically completely from conventional static molds to continuous casting machines. The Aluminum Company of America alone has more than 60 continuous machines in operation. The product as continuously cast is superior metallurgically, less scrap loss is involved, costs are generally lower, and the equipment requires little floor space. A continuous machine, operating as it does with deadly constancy, is a ravenous consumer of molten metal, and in most plants one or two machines are well able to handle large banks of melting and refining furnaces. In steel, interest in continuous casting is today more serious than ever before in history, and there is every reason to believe that continuous machines may secure a minor place in the ferrous industry, particularly for tool and alloy analyses. In the past, steel has been commercially cast continuously, and today many tons of steel are being turned out in this manner. It has been said that the cradle of every science is surrounded by dead theorists— and certainly there are innumerable examples of this in the metals industries. An excellent illustration, for instance, is the continuous rolling of metal, a tantalizing objective that for decades on end exhausted . the efforts of a long line of famous, infamous and unknown inventors. Finally, in 1922, John B. Tytus, of the American Rolling Mill Co., brought forth what now seems such an obviously simple scheme— a concave roll face, each stand of progressivcly less concavity. And out of this one change in design sprang today's wide continuous mill rolling steel sheet Ioo in. wide at 2000 ft. per minute. Another excellent example is the con- . tinuous casting of liquid metal into an intermediate form, preferably one requiring little subsequent breakdown. First, the casting of liquid metal alone was fascinating enough. Then someone passed the cast metal directly into a rolling mill, and shortly thereafter this continuously rolled strip was passed directly into a stamping machine. This leitmotiv of a continuous flow of metal from the liquid phase to a consumer end product, fast and inexpensive, and all housed within a small space, was enough to drive some 200 or so inventors into frenzy over the past hundred years. All the ideas, however, like mayflies, had only their brief afternoon of existence. They were born and they died on paper, as constant exemplification of that great void that always exists between mental production and commercial production.

Jan 1, 1945

By Charles Barnhart

This paper is a discussion of the causes of deflagration in cast blasting and a description of a project intended to demonstrate how changes in six critical parameters contribute to the deflagration chemical reaction. Control of these parameters is key to solving the nitrogen dioxide “orange smoke” problem. Preliminary results of an investigation into the development of a technology addressing the problem of atmospheric releases of nitrogen dioxide during cast blasting in surface mine operations are described. The project is funded by a $600,000 Small Business Innovative Research grant from the National Science Foundation and an $80,000 Abandoned Coal Mine Land Reclamation Program grant from the state of Wyoming. The presentation will address the measures required to control the blast chemical reaction so that it does not produce nitrogen dioxide through deflagration. Experimental blast data will be focused on a new shaped charge detonation system designed to instantaneously bring the powder column to maximum velocity of detonation (VOD), thus insuring efficient detonation of the entire colulnn.

Jan 1, 2003

By Offler R, Lau J, Lea J. F

The stratiform and vein-type pyritic silver-Iead-zinc-copper sulphide deposits of Sunny Corner, NSW are hosted by acid volcanic and clastic sedimentary rocks of Middle Silurian to Early Devonian age. The rocks have been subjected to low-grade regional metamorphism (prehnite-pumpellyite facies) and three phases of folding and four faulting events are recognised. Pyrite is intensely fractured, indicating brittle deformation. Chalcopyrite and galena exhibit deformation twins and slip planes indicating ductile deformation; sphalerite and chalcopyrite show straight and curved grain boundaries and dihedral angles of 120° as evidence of annealing recryslallisation. Sulphur isotope ratios for 22 samples from five deposits range from 1.7 to 10.7 per mil and average 7.4 per mil. Sulphur isotope data are similar to those from other stratiform sulphide deposits in acid volcanic rocks of Late Silurian age in the eastern Lachlan Fold Belt, especially Woodlawn and Captains Flat and together with other features of the mineralisation, suggest a volcanic exhalative origin for the Sunny Corner deposits.

Jan 1, 1984

By G. Noce

The ever more present necessity for greater precision in foundation structures on vertical piles subject to horizontal forces applied to the heads, in the light of of the latest knowledge about the elastic-plastic behaviour of the soil has led to the use of numerical calculation for the formulation of a general resolution method for the problem. The calculation method that will be set out, applicable to piles with inertia moments variable discreetly along their axes is especially useful when studying steel structures for medium and large tonnage vessels for which the metal piles are often constructed for the assembly of section of equal external diameter but different thickness and therefore different inertia moments. Two examples are given of constructions whose foundations have been projected with these calculation tools, one in the railway sector (foundation pile for the river Nera viaduct - Italy) important for the limitation of horizontal relative deck displacement, the other maritime (Dolphins of the petroleum pier of the port of Bandar Abbas - Iran).

Jan 1, 1989

By LeRon E. Bielak

Public Law 103-426 was signed into law in October 1994. Its provisions amended sections 8(k) and 20(a) of the Outer Continental Shelf Lands Act (OCSLA). The 8(k) amendment provides the Secretary of the U.S. Department of the Interior 001) with new discretionary authority to negotiate agreements for using Outer Continental Shelf (OCS) sand, gravel, and shell resources for certain projects of public benefit (e.g, beach, shoreline and coastal wetlands restoration that are under- taken by a Federal, State or local government agency). The new law also covers construction projects that are funded wholly or in part or authorized by the Federal Government. Under the law, the Secretary may assess a fee for use of the resource by taking into consideration the value of the resource and the public interest served. The law also requires that any Federal agency proposing to make use of OCS sand, gravel, or shell resources enter into a Memorandum of Agreement (MOA) with the DOI. An MOA would promote efficient coordination and resolution of inter- agency scheduling and issues. The law requires that Congress be notified before use is made of these OCS resources. The amendment to section 20(a) of the OCSLA clarifies that obligations concerning environmental studies extend to non- competitive lease situations and includes minerals other than oil and gas. The Minerals Management Service (MMS) is the DO1 agency responsible for interpreting and implementing the provisions of Public Law 103-426. The negotiated agreement approach is distinctly different from the competitive bidding requirements that have applied to all OCS minerals since the inception of the OCSLA. The MMS has opted to implement the new law in a nontraditional manner. Rather than issuinga body of new regulations to cover the negotiated agreement situation, or attempting to amend three sets of existing regulations, MMS is pursuing a less formal approach of providing guidelines. More weight is placed on the negotiation process itself and the legal agreement that consummates the process as the means for establishing ground rules, terms, and conditions under which qualifying projects may be conducted. This process must recognize and adhere to requirements of other laws, including the National Environmental Policy Act.

Jan 1, 1995

By Harold C. Pierce

"INTRODUCTION During the years 1941 to 1945, the United States produced less than one-half of one percent of all primary nickel, whereas the nation's consumption of the metal amounted to nearly three-fourths of the world's supply. Although postwar nickel consumption probably will be less than wartime consumption, trade- estimates for the next 10 years are well above the average established during the 1930-1940 decade. The greatest consumption is expected in nickel alloys, particularly nickel-alloy steels. 3/ The greater use of nickel cast irons and nickel-clad metals also signifies an expanding nickel market. In anticipation of the postwar demand for nickel, and realizing the seriousness of the ""have not"" position of the United States with respect to this metal, the Bureau of Mines, sent an engineer 4/ into the lower Copper River region of Alaska during the summer of 1944 to investigate the nickel deposits near the head of Canyon Creek. Samples from the Spirit Mountain nickel prospect were sufficiently encouraging to justify more intensive exploration. As a result, a program of surface trenching, systematic sampling, and detailed mapping of the property was adopted and directed by a Bureau of Mines engineer 5/ in the summer of 1945."

Aug 1, 1946

By Don Dodds

Iron Mountain Mine Rehabilitation Project Brief History The Iron Mountain Mine is located in Northern California approximately 12 miles northwest of Redding. The ore body is a large, very dense pyritic intrusion, discovered in 1860, and initially minded for silver. The silver played out quickly and 34 years later the ore body was mined for copper. Copper mining was scheduled to cease in 1939, but WWII prolonged the closure. After WWII, the pyrite ore was mined to produce sulfuric acid. In 1949 when large amounts of cheaper sulfuric acid were being generated by the oil industry the underground mine shut down. Little was done with the site conditions until 1970 when the U.S. Bureau of Mines began monitoring the pH of the effluent. The initial pH readings were around 2.0. This was lower than anyone expected. Laboratory tests showed that when the ore from the mine was submerged in water, the pH of the water would stabilize above 4.0. However, the pH got steadily lower. In 1989 with the ph around 0.7, the U.S. Environmental Protection Agency (EPA) required the owner to build a capture and treatment facility. During this initial period, the majority of the effort was spent on the treatment plant. The relationship between the mine owner and the EPA was basically an adversarial relationship from the very beginning. In 2001, North Pacific Research was hired to upgrade the capture and control facility. The general layout of the Iron Mountain Mine is shown in Figure 1.

By Read T. A

THE Broken Hill South Ltd. is one of ten companies operating on the Broken Hill lode (See Fig. 1). It has two leases-Blocks 7 and 8-of a total length of 2250 ft. on strike of lode.From the surface to 425-ft. level the ore was found principally in the form of carbonates and high-grade friable sulphides. Below the 425-ft. level the ore is found in the form of compact sulphides. The ore-bodies found in the South mine may be broadly divided into two classes...

Jan 1, 1921

By T. Seal

Hydro-Jex© releaching was undertaken during the summer of 2010 at the Valley Leach Facility (VLF) at AngloGold Ashanti?s Cripple Creek & Victor Gold Mine. Several advancements to the technique were made in response to the technical design and operational challenges posed by the unique site conditions. New geophysical resistivity monitoring techniques were developed to monitor solution migration during the injections. These developments are presented along with discussion of gold production resulting from the project.

Jan 1, 2011

By Ralph M. Hunter

UNTIL recent years, maintenance of surface coal handling facilities was a relatively simple task. Equipment consisted principally of conveyors, screens and crushers of comparatively simple construction. Electrical equipment consisted of motors and starters, with little, if any, interlocking. In most cases failure of any component affected only the grades of coal loaded so that even a prolonged break-down did not affect mine operation materially. However, with the introduction of modern cleaning plants, the picture has changed. The equipment is much more complex and therefore more difficult to maintain. In many cases failure of any component of the plant prevents loading of coal. Even if provision is made to by-pass, the quality of coal loaded is lowered, affecting markets. In the case of plants designed to permit full seam mining, marketable coal cannot be loaded without operation of the cleaning plant. Under these conditions it is apparent that considerable thought and effort toward better maintenance are justified. In order to assure continuous, efficient and economical operation, maintenance should receive consideration, not only after the plant is in operation, but while it is being designed. It is hardly necessary to say that the designer should strive for sturdiness and wearing qualities. It is sometimes not realized, however, that even the best parts will sooner or later require replacement or repair. The designer should, therefore, give consideration to accessibility. Anyone who has had to do with cleaning plant maintenance is familiar with installations where several hours are required to get at a part that can be repaired or replaced in a few minutes, once it is accessible. As in most cases, experience is the best guide. The men who operate and maintain this equipment know the problems encountered. Whenever available, the opinions of these men should be sought and heeded. As an example, we might consider the refuse elevator on a Chance Cone. Our company is now operating three of these cones, the first of which was installed in 1941, and the latest in 2946. Exact records are not available, but well over 50 pct of delays charged to the Chance Cones have been caused by the refuse elevator. This elevator receives refuse from the cone and carries it to a point above the water level of the cone, discharging onto a dewatering and desanding screen. Since the elevator operates under water and necessarily has close clearances in the lower boot, it tends to jam on large pieces of refuse or tramp iron. The chain, buckets and boot are also subjected to the action of water, sand and refuse, which accelerate normal wear. In case of jamming or chain-breakage it is necessary to drain the elevator and the cone so that even a minor fault in the elevator causes a considerable loss of time for the cone. In our new plant, which will contain two Chance Cones, the refuse elevator has been eliminated. This was accomplished by raising the cone so that the refuse gates could discharge directly onto the dewater-

Jan 1, 1948

By Li Zhou

The kinetics of the dissolution of galena was studied by monitoring the mixed potential of a galena electrode in ferric sulfate solutions. The results show that the mixed potential of the galena electrode fluctuated with time in a regular pattern in a 0.1 mol/L Fe2(SO4)3 solution of pH 1.66 and in a 0.01 mol/L Fe2(SO4)3 solution of pH 2.33 at 35°C. The periodic accumulation and precipitation of lead ions at the galena electrode surface and the cyclical variation in pH at the galena electrode surface caused the oscillation phenomena.

Jan 1, 2008

By Frank K. McIntosh

The Hamme tungsten district is in Vance County, N. C., and Mecklenburg County, Va. Principal development has been in Vance County. The district is approximately 8 miles long by 1 mile wide and extends northeast-southwest. Its center is about 3 miles N. 65° W. of Townsville, N. C. The occurrence of tungsten in the district was first reported in 1901, but it was not until the Hamme brothers revived interest in the deposits in 1942 that commercial development began. The Bureau of Mines, as part of the war minerals program, began exploration and development of the district in June 1943 and completed it in December 1943. The Federal Geological Survey cooperated by mapping the topography and geology and logging the drill cores. The program included mapping, trenching, sampling, diamond drilling, and analyses and beneficiation of ore samples, The principal ore mineral is hubnerite, which occurs in quartz veins within the schist and granite. The veins are generally lenticular along the strike and dip. About 50 quartz veins have been noted in the area, but many are barren or slightly mineralized.

Jan 1, 1948

Judicious placement of a range of geotechnical instruments was employed at the Tasmania gold mine, Beaconsfield, Tasmania, as a key strategy in the monitoring of rock mass conditions over the past four years. The range of instruments employed included vibrating wire stress-meters and hollow inclusion cells to monitor changing stress conditions, resistance wire and multipoint borehole extensometers to monitor the impact of stress changes on the integrity of the rock mass, and instrumented cable bolts and threadbar bolts to monitor the static and dynamic impact of rock mass changes on the installed ground control system. Initially the monitoring was of a qualitative nature, monitoring change from the time of installation. The value of the output was considerable when considered in relation to the ongoing seismic record which was also being monitored. It was clear from the seismic record and the monitoring results that stope blasting was the primary trigger for changing rock mass conditions. However, it was unclear how well observed behaviour was reflecting conditions anticipated by elastic numerical modelling. The latter had predicted significant stress increase in the near field of man-access footwall development. Qualitative monitoring and visual inspection did not support the modelling prediction, and this led to a program of quantitative measurement being undertaken. Measurement of the absolute stress condition in the backs of footwall development immediately adjacent to monitoring hollow inclusion cells provided the benchmark for tracking quantitative stress change. The program provided insight into the evolution of principal stress field magnitude and orientation in relation to rock mass change observed with extensometers and instrumented ground control elements, as well as providing a degree of calibration between the elastic numerical modelling and the virgin stress field. Calibrated monitoring data has also provided a useful benchmark for finite element modelling which is to be used for future mine-wide design.

Nov 25, 2010

By T. Yegulalp, M. Castaldi

As global energy demands increase, there will be a critical need to employ fuels that have minimal environmental impacts. While hydrogen is considered the ultimate fuel for that purpose, hydrocarbon based fuels will be in use for a considerable time and will probably be the first major source of hydrogen for next generation power systems. The best fuel for this transition will be natural gas because of the high hydrogen to carbon ratio. Natural gas hydrates have the potential to meet the global energy needs for the foreseeable future. The amount of energy stored in natural gas hydrates is significantly more than that of all the other fossil fuels combined. However, most proposed techniques for recovering the natural gas from the hydrate require too much energy input, raise safety concerns or can only recover a fraction of the gas. This paper discusses the technical feasibility of a novel method of gas production in hydrate reservoirs. The method is an in-situ process that creates a point heat source in the hydrate formation. This method not only significantly reduces the energy input, but also has the potential to sequester as much or more CO2 than would be produced from combustion of the natural gas produced, thus making this in-situ methane production technique virtually carbon neutral. Simulations using FEMLAB™ show that the method offers an energy efficient and environmentally friendly way to produce natural gas from hydrate reservoirs. Preliminary results indicate that it is possible to have an energy efficiency of nearly 90% for land based reservoirs for hydrate loadings of 20%. The simulation results also suggest that alternatives to a point source can be employed which may improve the process efficiency.

Jan 1, 2007

By Y. H. Hatzor, D. Bakun Mazor

"A new model for thermally-induced block displacement in discontinuous rock slopes is being explored inside a Controlled Climate Laboratory (CCL). The model is based on a hypothesized wedging mechanism that takes place inside the filled tension crack of a discrete block that rests on an inclined plane. Irreversible block sliding is assumed to develop in response to climatic thermal fluctuations and consequent contraction and expansion of the sliding block material. While an analytical expression for this model is already available, we are exploring the possibility of obtaining such a permanent, thermallyinduced, rock block displacement, under fully controlled conditions in the laboratory, to enable effective analysis of the sensitivity of the mechanism to geometry, mechanical properties, and temperature fluctuations.A large scale (approximately 0.5 m3 in volume) model consisting of four blocks has been installed in the CCL. The CCL permits accurate control of atmospheric temperature (?0.5 °C) from 6 °C to 45 °C. Harmonic temperature function is planned in advance and is controlled by a computer program throughout the experiment process. The minimum length of the temperature cyclic period for thermally-induced block displacement is calculated here based on the existing analytical model.Due to the fact that this experiment is still in progress, preliminary results will be available in the next few months. The obtained results may explain sudden triggering of rock slope failures that are not correlated with common failure triggers such as seismic activities, pore pressure build-up, or freezing and thawing of water inside rock joints."

Jan 1, 2015

By Dirk Bergmann

During the spray forming process, a continuous molten metal stream is atomized by impinging high speed inert gas jets. In the generated spray cone, the resulting metal droplets are rapidly cooled by the huge temperature difference to the surrounding gas phase and thereby partly solidified during flight. After a certain flight and residence time inside the spray cone, the droplets impinge onto the solid substrate and form the product (deposit) by compaction. Material properties of this preform strongly depend on several process parameters and especially on the thermal and kinetic state of the deposited droplets at the point of impingement. Smaller droplets may cool very fast due to their low mass and impinge onto the product in a completely solidified state as solid metal powder particles. Larger droplets with big mass contain a higher amount of thermal energy and impact during the state of phase change or still as completely liquid. It is obvious, that a certain amount of liquid content in the droplets is needed for forming a homogeneous deposit. Therefore, the thermal history of metal droplets during flight in the spray cone is of great importance for overall process modelling and control. Modelling the effects of the impinging droplet mass on the formation and heat balance of the deposit, the thermal conditions of the droplet stream need to be temporary and spatially averaged at different locations. Averaging may be achieved in different ways, giving alternative results. A first method is averaging over the droplets total enthalpy which consists of the thermal content and the remaining latent heat of fusion within the droplets. A second method may yield the average over the heat content and the solid fraction separately. Results of these two methods depend on the application and the kind of information which one wants to achieve and show some deviations, which will be discussed in terms of consolidation and energy conservation of the deposit.

Jan 1, 1999

By Daniel Harrington

On the night of June 8, 1917, the flame of a carbide lamp accidentally set fire to the uncovered and frayed insulation of an armored power cable near the 2,400-foot level of the North Butte Mining Co.'s Granite Mountain shaft. How this insulation accidentally became exposed is explained on page 15. The highly flammable oiled fabric set fire to the shaft timbers, and as this is a downcast shaft the fire spread with great rapidity, soon filling the mine workings with smoke and gas. At the time 410 men were working underground, 247 of whom escaped by various means, but most of the 163 remaining were probably overcome soon after the lire started, and perished. Only two men were actually burned. The cause of the disaster was purely accidental. The immediate effect was the unexpected reversal of normal conditions; the ultimate effect was great loss of life and the destruction of the main hoisting shaft, putting it temporarily out of service. The work of rescue and fire fighting continued eight days. The following pages present an attempt to draw some practical conclusions and suggestions from this disaster. The property of the North Butte Mining Co. consists of about 220 acres in the northeastern part of the Butte district, Montana. Next to the Anaconda Copper Mining Co. it is the largest pro¬ducer of the district. In 1916, the year before the disaster, there were 1,160 men employed. The output was 560,947 tons of ore, which yielded 24,498,181 pounds of copper, 1,047,063 ounces of silver, 1,712 ounces of gold, and 412,953 pounds of zinc. The profit was $2,479,595. The total development work for that year was 21,694 feet. During the first half of 1917, the year of the accident, the daily tonnage of ore averaged 2,000, an increase of 400 tons over that of the year 1916.

Jan 1, 1922

By R. A. Wood, R. I. Jaffee, H. R. Ogden, D. N. Williams

Dispersion-containing titanium-copper alloys were prepared having mean free paths varying from 1.0 to 9.7 P. Tensile studies at room temperature and at 1000°F showed that little or no strengthening occurred when the mean free path exceeded 3 p. However, at lower values of mean free path appreczable strengthening was observed. A considerable amount of strengthening also resulted from copper in solid solution. DURING the past several years, an increasing amount of study has been devoted to dispersion hardening, an alloying process in which increased strength is obtained through the addition of a ran-

Jan 1, 1961

"With millions of dollars and thousands of lives at stake, the Iron Ore Company of Canada (IOC) turned to a private wireless network for help.IOC needed a network that possessed the ability to adapt to changes in a nanosecond and to function seamlessly in the most rugged of environments.Canada’s largest iron ore producer required a private wireless network powerful enough to support all mine applications and deliver all data to one central point — without any existing cellular/3G/Wi-Fi coverage.Operations at IOC, a leading global supplier of iron pellets, involved dispatch, drill management and equipment monitoring, pump control and remote video that must service three distinct pits. Due to its setup, the facility does not offer a great deal of flexibility for transmitting signals.IOC serves a robust customer base made up of North American, European and Asian steel producers. It also employs nearly 1,900 people. Catastrophic death and destruction are two very real potential consequences of system communication failure.Technology for tough terrainKinetic mesh technology was born in the wake of the 9/11 terrorist attacks on the United States, one of the most high-stakes emergency situations in U.S. history. The failure of the communications infrastructure on a massive scale that day underscored the need for networking technologies that could provide service even in the most chaotic of conditions.Kinetic mesh networks allow organizations to deploy networks at sites where communications infrastructure has been compromised, as well as quickly establish networks in places where they did not previously exist. Kinetic mesh networks have also demonstrated a better ability to adapt to network changes on-the-fly versus other types of networking technologies."

Jan 1, 2015