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By S A. Myers, T Klein

The Yanacocha mining district is located in the northern Andes of Peru. The project is within the Cajamarca province, 20 km north of the town of Cajamarca and 600 km north of Lima, the capital of Peru (Figure 1). The district encompasses an area of 120 km 2 and is centred on the 78030'west longitude and 7000' south latitude. The project lies at an elevation of 3400 to 4200 masl.

Jan 1, 1999

By B. E. Burakov, S. D. Lupal, O. A. R. Thalhammer, B. Saini-Eidukat

Electric-pulse disintegration is a mineral separation technique that liberates all mineral grains from any igneous or metamorphic rock irrespective of its lithology or grain-size distribution. The normal mechanical crushing of whole-rock samples is replaced by the rending effect of an explosion, produced by applying an electric current from a high-voltage power source. A voltage greater than the 100 kV necessary for the electrical breakdown of rock samples is achieved by using capacitors charged in parallel, but discharged in series. The sample sits in a water bath and the rapid distribution of electric pulses leads to an explosion which occurs preferentially along grain boundaries of the sample. Individual, undamaged mineral grains can be recovered in their original shape and form regardless of grain size. Examples are given of the liberation and concentration of important accessory minerals from different rock types. The examples show the recovery of diamond from two types of non-kimberlitic host rock in Popigai and Kumdykol in Kazakhstan and platinum group minerals associated with chromitites from the Konjdor intrusion and sulphides from intrusions in the Kola Peninsula in Russia

Apr 1, 1995

By Peter Bigwood

Whether drilling through tough clay or breaking rock, or facing the most severe conditions including mixed face ground, perched water and running and flowing sands, working under-ground certainly comes with no shortage of challenges. In an environment where the unknown is faced on a daily basis, tunneling contractors must be able to rely on their equipment to get the job done properly. Not only that, their equipment must comply with two of the highest priorities: safety and efficiency. In addition to being the number one concern, a proven safety record provides additional benefits to a company. A safe work environment serves as a key component to company growth, including the ability to remain competitive in bidding and maintaining higher-level, more challenging projects.

Jan 1, 2012

The Precambrian Eastern Creek Volcanics comprises spilitic basalts with interbedded sediments and tuffs which were extruded and deposited during Middle Proterozoic time. The rocks have undergone low-grade regional metamorphism.The Eastern Creek Volcanics are approximately 17,000 ft thick and have been divided into four units.The rocks were laid down in a geosynclinal basin elongate to the north. The main structural features are the northerly trending Mount Isa and Gorge Creek-Quilalar fault systems.Major east-west faults cause repetition of the sequence.Copper and uranium mineralization is known within the formation. Copper mineralization is confined to quartz-filled shears anp basalts. Nothing of economic importance has been found in the area though ore deposits have been found elsewhere in this type of environment.

Jan 1, 1968

By B A. Tapp

The minerals industry in Australia is currently regarded as the country's economic saviour; the bastion of economic security. As Fitzgerald (1974) stated, 'Australia's natural endowments in minerals are the envy of most countries of the world'. As a result the proposed new mineral developments are on a scale that hitherto in the sixties would have been completely un-envisaged. It is reported that Australia is poised on the verge of a 16 billion dollar mining-based investment boom: a boom that will see Australia dominate the energy export field, the mineral processing field, and create the 'coal dollar'. This growth scenario has many inherent dangers, and it is the authors' contention that these should be carefully considered before further development proceeds. Two of the major problems related to the mineral industry growth scenario are the predictability of the future metal market, and the energy cost of mining. The latter problem is the one discussed here. The mining-mineral processing industries in Australia currently use about 36 per cent of Australia's primary energy budget. This large energy input is dominated by two major industries, iron and steel and the rapidly developing a1uminium industry. These two combined use over 20 per cent of the total Australian energy budget. In an industry which is export oriented about 96 per cent as expressed in ex-mine value terms û much of the energy input is exported along with the product. The authors therefore urge that serious consideration by the mineral industry be given to the relatively high energy intensiveness of process operations, especially in respect of the aluminium industry.

Jan 1, 1980

By R. A. Bullivant

Roger Bullivant Piling Limited has started 1992 with the introduction of the CONE PILE into its range of precast concrete foundation techniques. Since the establishment of its Piling Division ten years ago, alongside the original Underpinning Company, a commitment to innovated development has seen a steady growth in Roger Bullivant's activity in piling, ground treatment and general foundation engineering. Over the last four years, £1.2 million has been invested by the Bullivant Piling Division into research and development in the field of precast piling and other foundation systems. The goal has been to develop economically attractive systems tailored to our clients design requirements and, wherever possible, unique to Roger Bullivant Piling.

Jan 1, 1992

By G. V. R. Landman

It is self-evident that economic pressure demands that today?s mines stay ahead and stay competitive. The challenge, however, isto find fresh approaches to the pursuit of efficiency and operational effectiveness. Rather than focusing on individual activities in isolation, a process that can lead to poor investment decisions affecting other critical areas of operation, a key concept is optimization of the whole value-adding process of mining. This concept is often called ?mine to mill?. Whereas it is never easy to establish optimal conditions across a whole mining operation, the quality and consistency of the blasted rock strongly affects all operations. In many instances an inability to control rock breaking has been unchallenged, leading to significant investment in time and money to manage the consequences of poor and/or inconsistent rock breaking. This paper discusses how electronic initiation systems can play a major role in optimizing the whole mining operation. Electronically programmed detonators provide not only the ability to tightly control a key parameter, namely timing, but also the opportunity to extract blast data for a continuous improvement process. The ability to alter predictably, using feedback from the downstream processes, blasting variables such as fragmentation, throw, wall stability, and vibration, is a huge advantage. The current understanding of the effect of timing, accuracy, and scatter on rock fragmentation is reviewed and offers reasons why there is significant progress in controlling blast results. Two case studies are examined, which demonstrate the benefits of the technology on the economics of the operations under review.

Jan 1, 2010

By J J. McEwan

Silver tarnishes readily in common atmospheres and is accelerated in humid atmospheres. Tarnish is the formation of silver sulphide on the surface of silver when it is exposed to a wide range of sulphur-containing atmospheres. Tarnish is unattractive and highly undesirable, and can be removed either with a silver polish or a chemical dip. Dips are generally only recommended when heavy black tarnish cannot be removed with a polish, and care must be taken during cleaning because these can contain aggressive chemicals and give off hazardous and unpleasant smelling fumes. Polishes work best for large areas of plain undecorated silver, and form part of a regular cleaning programme. Some polishes contain chemicals that inhibit tarnishing, but these generally only have a short life. Several methods have been developed to reduce tarnish formation on Silver; these include alloying, surface treatment, and coatings. The authors evaluated a range of self-assembled monolayer (SAM) surface treatments and coatings in earlier research. Four treatments/coatings increased the time to noticeable tarnish by more than ten fold, and the results were reported at the International Corrosion Congress (ICC) in 2005, and at the Mint Directors Conference (MDC) in 2006. SAM treatment using 95% 1-hexadecanethiol (C16H34S) was found to give good anti-tarnish performance and showed potential for the commercial treatment of Sterling silver. Therefore research was performed to optimise the methods of application of this type of coating to provide an easier, faster, and more-user friendly technique to provide an anti-tarnish treatment. Keywords: silver, tarnish resistant coatings.

Jan 1, 2006

By John E. Rourke, O&apos

This report documents the process of site selection, instrument installation, data acquisition, and preliminary data analysis followed to characterize the physical response of overlying strata to longwall mining. A system of surface, subsurface and mine level instrumentation was installed at the Allen Mine in Weston, Colorado where the overburden varied in thickness from 600 to 900 feet. Survey monuments, automatic-recording strain-meters, multi-point rod extensometers, inclinometer-extensometers, stressmeters and tape extensometer convergence stations were installed to monitor displacements and stress changes. A preliminary analysis of the data acquired up until project termination has shown the system to be operative and strata response to be similar to that reported for other subsidence monitoring case histories. Recommendations for continued monitoring of the instrumentation systems are presented.

Jan 1, 1982

By J. W. Howland

A demonstration of dozer blades, designed for recontouring area-mined spoil and shown effective at Kansas and East Texas surface mine sites, was conducted at a Northeast Arizona surface coal mine to determine their effectiveness in different climate and soil conditions. The specialized tools were: 48-ft angle blade (on side-by-side tractor), 24-ft grading bar, modified 24-ft "U" blade (on side-by-side tractor), and a 13-ft deep "U" blade. Interest in the increased dirt-handling capacity of a previously built 22-ft blade, resulted in the design of a new Centerflow Blade of good versatility, able to maintain increased flow in otherwise difficult-to-move spoil. The demonstration involved 263 acres and showed a reduction of 50% in reclamation costs and 20% in fuel requirements for this mine site over conventional equipment. This savings resulted from improved technology, trained operators, and rigorous application of supervisory and monitoring techniques. Procedures and results of the demonstration are presented and analyzed here, along with guidelines for application of findings.

Jan 1, 1982

By M. J. Nicol

The kinetics of the dissolution of colloidal silver in aerated cyanide solutions has been investigated with the aim of developing a relatively rapid and convenient method for monitoring the ?leaching power? of solutions typically used in the cyanidation process. Experimental results obtained are consistent with an electro-chemical model, in which the mixed potential is set up in the active region of the polarization curve for the anodic dissolution of silver, giving rise to a rate of dissolution which is controlled by the rate of mass transport of either cyanide or oxygen to the surface of the silver. The rate of dissolution of colloidal silver was found to respond to variations in the reactant concentrations in a similar manner to gold (and silver) in a typical free-milling ore. The use of this technique for the monitoring and control of the cyanide leach process is discussed.

Jan 1, 1998

Innovative Technology for Optimised Thickening Sedimentation

Sep 13, 2010

By Rao P. K, Sahoo P. K

The main constituents of ferromanganese slags are silicates of Mn, Ca and AI. Factors affecting the recovery of manganese from a low manganese content ferromanganese slag (about 16 per cent MnO) during acid leaching were studied. These included time, temperature, agitation, sulphuric acid addition, solid:liquid ratio and particle size. Agitation rates greater than 300 rev/min. leaching periods greater than 30 min and temperatures above ambient were found to have no effect on Mn recovery. Dissolution of Mn was found to be highly dependent on the amount of acid added.About 90 per cent of the Mn was recovered when 5·5 times the stoichiometric amount of acid was used. About 28 per cent of the Mn was recovered when the stoichiometric quantity of acid (with respect to Mn alone) was used. However, the recovery increased to about 75 per cent when the total stoichiometric requirement of acid with respect to Ca, Al, Mg and Fe as well as Mn was used for leaching. The extent of Mn dissolution also depended on the particle size of the slag. The percentage of Mn recovery (using 5·5 times the stoichiometric amount of acid) increased from about 60 per cent to about 92 per cent when particle size decreased from -36 +52 to -150 +200 mesh (B.S.S.). When the results of this study were compared with those in a previous study involv,ing the leaching of a high manganese content slag (containing about 40 per cent MnO) results were similar except that there was a gr-eater consumption of acid in the present case (i.e. low manganese content slag).

Jan 1, 1979

By J. I. Muñoz González

El presente trabajo verifica la utilidad de la incorporación de algoritmos de inteligencia artificial (IA) en cuanto a mejorar los resultados obtenidos en campañas de sondajes de exploración. Tomando la información geológica, geoquímica y geofísica de un proyecto real de exploración, se simularon 3 campañas posteriores y consecutivas, utilizando algoritmos de “boosted regression”. Luego fueron comparados con los resultados reales de los mismos.

May 1, 2008

By C. J. Brown

Controlling the level of impurities in copper refinery electrolytes is essential to achieving acceptable cathode purity. Purge of electrolyte is not an entirely satisfactory solution since the cost of neutralization, waste disposal, and replacement acid can be appreciable. The APU® process utilizes ion exchange resin to sorb sulphuric acid while rejecting metal salt impurities. Extensively employed for recovery of waste pickling and anodizing acids since 1977, the system is now being used at several refineries for removal of contaminants such as antimony, bismuth, iron, and nickel. The purified acid, which is recovered from the resin by water elution, is recycled back to the refinery tank-house, while the metals are typically recovered from the de-acidified by-product solution by precipitation.

Jan 1, 2005

Zircon producers are often required to lower impurity levels to meet customer specifications as most of these impurities adversely effect the end use. For example, zircon sand in foundry applications needs to be free of any surface impurities (eg clay, gibbsite and goethite) which otherwise could cause sintering or fusion between cast metal and the zircon mould. Light coloured ceramic grade zircon, typically low in iron oxides and titania, is preferred in ceramics applications. The presence of impurities in zircon sands is a problem in the magnetic and electrostatic separation stages of their concentration. Previous work (Aral et al, 1997) showed that impurities in zircon sand concentrates occurred in the form of stains on grain surfaces, discrete gangue minerals and in the mineral grains. The gangue minerals such as rutile, garnet, xenotime, monazite, spinels, ilmenite, and aluminium silicates in the concentrate in some cases (Aral et al, 1997) contribute significantly to the impurity content of the concentrate. A careful hand picking of the impurity grains from a Western Australian zircon sand showed that the impurity content of the concentrate could be lowered significantly as a result of the removal of the surface stained grains and gangue minerals. The hand-picked ædirtyÆ fraction, comprised about eight per cent by weight of the concentrate, and consisted mostly of iron-oxide/hydroxide-stained zircon, silica grains and rutile, and occasionally ilmenite, monazite, gahnite and other (unidentified) coloured grains. The chemical analysis of the remaining æcleanÆ fraction showed that the major impurities (Fe and Ti) were reduced significantly (Table 1). The reduction in the uranium content was about 30 per cent. The other measured impurities, P, Mg, Al, Th, and Ca remained mostly unchanged as shown in Table 1. The contribution of ilmenite to the overall iron content of æcleanÆ zircon was insignificant as it comprised about 0.1 per cent weight of the æcleanÆ zircon. Rutile was the major source of titanium contamination (about one per cent by weight). Recent work (Aral and Calle, 1999) on zircon sand concentrates from the Murray Basin showed that, under the electron microprobe, the bulk of the impurities occurred in the dark back scattered electron (BSE) regions of the zoned zircon grains. The impurity contents of the light BSE regions and unblemished (unzoned) grains were low. The impurity content in zoned zircons has been investigated on single, relatively large, crystals (McLaren, Gerald and Williams, 1994; Smith et al, 1991; Romans, Brown and White, 1975). These studies generally aimed to investigate the incorporation of U in zircon as zircon is used extensively for U-Pb geochronology owing to its relatively high content of uranium. Smith et al (1991) identified a striking difference in composition between the areas of lower (dark BSE) and higher (light BSE) average atomic number in the zoned zircon. Their work showed in particular that the zones of lower atomic numbers contained very significant amounts of trace metals such as Y, REE, Nb, U, Al, Fe, Ca, Ba and, by difference H2O. In this paper the impurity distribution in zoned zircon grains was investigated on statistically significant number of grains before and after a leach treatment. The distribution of impurities was also measured in unblemished areas to compare the results.

Jan 1, 2000

The Rate Variable Batch Test (RVBT) - A Research Method of Characterising Ore Floatability

Sep 13, 2010

By D. D. Banerjee, S. K. Kawatra, T. C. Eisele

A high calcium fluid-bed combustor ash has been shown to be an effective binder at dosages of 1 to 2% of the magnetite concentrate weight. Magnetite pellets 1.3 cm (1/2 inch) in diameter were produced with dry crushing strengths greater than 22.3 Newtons/pellet (5.0 pounds force/pellet), which is comparable to the results produced using conventional bentonite binder. The effectiveness of fly-ash-based binders was considerably improved when calcium chloride was added as an accelerator. Addition of calcium chloride at a rate of 0.1 to 0.2% of the total powder weight increased the strength of dried pellets by as much as 22% compared to the strength of pellets made using fly-ash without accelerators.

Feb 24, 1997

By Amy B. Cerato

The application of this study is to use helical anchors as a foundation system for small wind tower (1 ? 10 kW) guyed cables. Helical anchors are currently used to anchor guyed cables of telecommunication and electric towers. However, the increased dynamic vibrations a wind turbine adds to the tower and foundation system under working loads, as well as extreme environmental conditions (e.g., straight line winds, ice load or sudden furling shocks), require additional knowledge about the behavior of helical anchors. These field conditions were simulated in this study by instrumenting a working tower with load cells and 3-axis accelerometers to gather data on wind speed and tower response. These tower responses were then transmitted to the helical anchors through an extensive, large-scale testing program that included monitoring the performance of the helical anchor foundation under dynamic loads, subject to natural variations in both wind regimes, precipitation (water level) and variations in helical anchor geometry. This paper specifically discusses the effects of helical anchor geometry on helical anchor performance under long-term dynamic loads.

Jan 1, 2008

By Michael Rehbock-Sander

The Gotthard Base Tunnel (GBT) is 57 km (35 miles) long and consists of two par-allel single-track tubes with an ex-cavation diameter ranging from 8.8 to 9.5 m (28.8 to 31.2 ft). These are interlinked by cross-passages every 312 m (1,000 ft). Two multifunction stations (MFS) are located in the sections Sedrun and Faido, at one-third and two-thirds of the entire tunnel length (Fig. 1). These will be used for the diversion of trains to the other main tube via tunnel crossovers, for the housing of tech-nical infrastructure and equipment and for potential emergency stops. To reduce construction time, the GBT was divided into five sections and was excavated from several sites simultaneously. The tunnel was excavated from the two portals, Erstfeld in the north and Bodio in the south, and also from three intermediate attacks, with their corresponding access tunnels, in Amsteg and Faido and two vertical 800-m (2,624-ft) deep shafts in Sedrun.

Jan 1, 2012