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By Malcolm Flavel

Dado que la trituración constituye el componente de alto costo en la mayoría de procesos mineros, se utiliza una tecnología basada en el resultado de los programas de investigación desarrollados por Allis-Chalmers Corporation. donde se busca reducir paulatinamente dichos costos. En ese sentido, el presente texto señala cómo reducir el consumo de energía requerida por el proceso de trituración y así minimizar la inversión de capital necesaria para construir las instalaciones del procesamiento.

Mar 1, 1983

By B. Caro Vargas

The Toulon Tunnel project is a key component of the highway corridor on the French Riviera between Marseille and Nice and is a fundamental transportation infrastructure for the region. The first design studies started in the 1960s. The tunnel project is comprised of two separate tunnels: south and north. The north tunnel was built between 1992 and 2002 after 10 years of difficult construction. On March 15, 1996, for example, a collapse of the tunnel in the Marchand area generated a sinkhole in the city center, causing a 20-month delay. The south tunnel alignment runs parallel to the north tunnel below Toulon?s historical downtown at a depth of 20 to 40 m (65 to 131 ft) with some areas with less than 10 m (32 ft) of cover. The risk management program was studied to be a state of the art program in urban tunneling construction.

Jan 1, 2012

By Michael Wieland

The resolving capacity of the thermodynamic work-principal model has been seriously refined over its twelve year history, so a review of the innovations, wrong turns and their rectification is warranted to help future researchers. The work-principal model rests upon the four laws of thermodynamics that drive the universe and relatively few other assumptions: like the removing and imposing of constraints on the quasi-potential to yield trapped minimum key-states that represent the wanted process. The formative research was concerned with the role of ingredient changes, the removal of booster influence and the quench temperature with which to reckon toxic fumes. The transfer of reaction-zone energy as work upon the surrounding rock/water/fixture was not fully rationalized until the notion of reversed-inertial pressure was formulated and determined (for water) with underwater trinitrotoluene (TNT) shots. The rock-water-jelly model incorporated that term into its dynamic pressure formula as a way to represent rock blasts or underwater shots, while the zone of reaction gases remained trapped. The real irreversible thermodynamic process, which yielded the total expansion work, was later complemented with a wholly reversible imaginary process, to form a closed thermodynamic loop, with a remarkable consequence – the determination of the theoretical heave and hence, the undissipated-shock by difference from the total work. With the wholly developed model, it was recently possible to quantify the time retardation of reaction chemistry for non-molecular (mining) explosives, as compared to the rather negligible time-retardation found for the molecular (military) explosives in underwater tests.

Jan 1, 2009

The risk associated with mining induced seismicity is one of the major threats to the safety and sustainability of deep underground mines. This paper describes techniques that allow site practitioners to efficiently control such risks in mines. The proposed approaches rely on ground support to strategically control seismic risk and re-entry time to tactically control this risk. The strategic approach is based on the detailed understanding of past seismicity to as certain the seismic hazard of individual sources throughout the mine. This approach also relies on assessing the potential damage that these sources can induce on nearby excavations using the excavation vulnerability potential (EVP) and rockburst damage potential (RDP) concepts proposed by Heal et al. (2006). It is then possible to investigate how to reduce the risk of experiencing damaging seismicity in mine drives by locally enhancing the ground support system. The tactical approach relies on a proposed methodology to estimate reliable re-entry times or exclusion periods based on the seismic decay following blasting. Some examples of how these techniques have been applied in Australian mines are given.

Jan 1, 2009

By V. Petr, G. G. W. Mustoe, T. G. Rozgonyi

We introduced a numerical method that is applicable for the analysis of static and dynamic deformations of elastic media. In this numerical study, each elastic body is modeled with a system of several hundred rigid particles that are joined together elastically. Maximum shear stress fields due to external loading are obtained and compared with those obtained by photoelastic experiment. Preliminary results are presented for the stresses generated in circular disk shaped bodies idealized with connected systems of particles. Extension of this simulation method to fragmentation of brittle materials is also illustrated in an example.

Jan 1, 2000

Retreating Cu-Mo Rougher Tailing by Flotation for Concentration of Copper and Molybdenum

Sep 13, 2010

Great new drilling results! What's so sinful about being a multi-national company? Overseas protestors flown to Australia for a free holiday How to counter the protectionist danger? Our current economic standing Over-regulation puts a convicted paedophile on the payroll The broken window fallacy Mining - A shared history Aristotle and the camels A brighter future? Something over which we do have far greater control, i.e. leadership within our own industry My challenge to you The expanding gold- producing company of which I am proud to be Chairman, Croesus Mining NL, is by definition a æmultinationalÆ. Our shareholders are based in 36 different countries, 77% of our 107 million shares are held in Australia, 23% are held outside Australia, and include New Zealand holdings of 7%. In September, Croesus Mining presented our company at the Mining 2000 Forum in Melbourne, a city caught up with multinational protestors demonstrating against multi-national companies.  

Jan 1, 2000

By X. Q. Cao, D. S. Zhang, L. Q. Ma

To solve the support stability control problem for a coal face with large angles along both strike and dip (CLSD), the ’support-surrounding rock’ mechanical model has been developed, which takes into account the impact of the dip angle of the seam on the stability of the support in the strike direction. The mechanical relationships of the critical topple angle and critical slip angle of the support along the strike of the coal face with large dip angle and the support height, support resistance, friction coefficient, and other factors have been derived through the mechanical analysis of support stability in the strike direction of CLSDs in the free state, the operating state, and the special state. The research findings were applied to a fully mechanized CLSD in Xinji Coal Mine. The maximum underhand angle and overhand angle in strike are 42° and 25° respectively, and the maximum dip is 39°. It is calculated that during underhand mining and overhand mining, the critical support resistances for avoiding support toppling are 3723 kN and 1714 kN respectively, and the critical support resistances for avoiding slipping of the support are 7405 kN and 6606 kN respectively. Thus, the selection of type ZZ7600/18/38 hydraulic roof support for the coal face is justified. Measures to prevent sliding of the support and the installation of a limiting stop maintain the support runs in good condition and ensure safe and efficient mining of CLSD.

Jan 1, 2015

By A. A. El-Midany

Traditionally, the choice amongst different upgrading techniques or in finding the optimum operating conditions for a given upgrading technology depends on whether one is looking at the grade or the recovery of the valuable mineral in the concentrate. In fact, the conclusions are not usually the same. This is because the best technique or optimum operating conditions for the highest grade are not the same as the conditions to achieve the maxi-mum recovery. Therefore, a unique measure that takes into consideration both grade and recovery is urgently needed. Finding such a measure is the objective of this paper. A proposed measure provides a selectivity index in the range of 0 to 1, where 0 is no selectivity and 1 is ideal selectivity. The index can be obtained by plotting the so-called Fuerstenau upgrading curve, which relates the recoveries of the components in products of separation and a running regression applying a one-parameter equation. The measure was applied to assess the selectivity of selective flocculation under different operating conditions when used as a sensitive upgrading technique for ultrafine ground ores. After applying the proposed selectivity measure in the case of the selective flocculation of ultrafine Egyptian iron ore without the addition of cations, it was found that the optimum conditions are pH 11, 1 kg/t sodium silicate and 0.4 kg/t potato starch with a selectivity index of 0.55. With the addition of cations, the optimum conditions were found to be pH 11, 1 kg/t sodium silicate and 2 kg/t potato starch with a selectivity index of 0.65. It should be noted that determining these optimum conditions using the traditional grade or recovery measures was highly ambiguous.

Jan 1, 2008

"Foreword by Emily SarverAssistant professor, Mining and Minerals Engineering, Virginia Tech, Blacksburg, VAThe Mineral Processing Division hosted its fifth Student Poster Contest during the 2014 SME Annual Meeting and Exhibit in Salt Lake City, UT – and, by all accounts, it was a huge success! This year, the contest more than doubled in numbers of individual entries and schools represented. A total of 30 students participated, including 23 graduates and 7 undergraduates, representing 13 US and international institutions: Colorado School of Mines, Michigan Tech, Missouri University of Science and Technology, Montana Tech, New Mexico Tech, South Dakota School of Mines, University of Kentucky, University of Utah, Virginia Tech, West Virginia University, Autonomous University of Chihuahua (Mexico), UNAL Medellin (Colombia), University of British Columbia (Canada). In addition to constructing their posters, students submitted abstracts and gave short oral presentations highlighting their research. Based on tallied scores from all three components of the contest, the judging panel selected 1st, 2nd and 3rd place winners at the undergraduate and graduate levels, which were announced during the MPD Luncheon on February 26.In the undergraduate division, University of Utah’s Lucas Pich was awarded the 1st place prize for his poster “Solid-liquid mixing studies in lab-scale flotation tank using electrical resistance tomography.” His extended abstract is included in this issue of Minerals & Metallurgical Processing. Joshua Chidester, also of Utah, won 2nd place for his poster presenting “Evaluation of detectors for radiotracer RTD measurement by MCNP.” And Lucas Rojas-Mendoza, of UNAL Medellin, took 3rd place for his poster on “Preg-robbing in Colombian gold ores.”In the graduate division, 1st place went to Caelen Anderson, of the Colorado School of Mines, who also placed in this contest in 2012 and 2013! The 2nd and 3rd place prizes were awarded to Jacob McDonald and Joseph Halt, respectively, both of Michigan Tech. Extended abstracts describing the work of these up-and-coming researchers are also included in this issue.The 2014 Contest was chaired by Emily Sarver (Virginia Tech) and Lisa Schlink (Freeport-McMoran Copper and Gold, Inc.). Aaron Noble (West Virginia University), David Perkins (Derrick Corporation) and Derek Novotny (Eriez) graciously served on the judging panel this year.Special thanks are extended to all sponsors of the 2014 MPD Student Poster Contest, and to all student participants. Please watch for upcoming details on the 2015 Contest. We look forward to seeing you in Denver!"

Jan 1, 2015

By Q. C. Reynolds

Keywords: Pyrometallurgy, plant, photography, GIS, satellite images, Google Earth Google Earth is a piece of software able to display an interactive three-dimensional map of the world, combining aerial and satellite photography with maps, terrain, and user-generated geographical information systems (GIS). Many structural features of the planet, both natural and man-made, are of great interest to the mining and metallurgy field, and in this paper a study is made of the current state of the art of data accessible by Google Earth.

Jan 1, 2006

By H Sofatzis, J Kinal, J Siliezar, B Kirkwood

Ernest Henry Mining (EHM) is a copper, gold and magnetite mining and processing operation located 38 kilometres north east of Cloncurry in the Mount Isa - Cloncurry mineral district of north west Queensland, Australia. The EHM ore body is an iron oxide copper gold deposit with an average grade of 1.1 percent copper, 0.5 g/tonne gold and 22 percent magnetite.At the end of 2009, after a series of promising laboratory test work, EHM converted the ball mill media charge from forged steel to high chrome media. Laboratory test work also indicated that with the use of high chrome media, the pH was able to be reduced with no negative impact on plant performance. At high pH values (above 10.5), the forged media is passivated, so as the pH of the system drops the media corrosion rate increases and floods the system with corrosion products, affecting flotation. As the high chrome media is much more inert, pH has less of an effect on copper flotation response.This paper provides an overview of the effects of reducing the pH in the EHM copper rougher flotation circuit. The pH in the roughers was dropped from 10.6 to 9.6 to determine the impact on the rougher performance and the subsequent performance of the whole copper flotation circuit. It was found that there was a slightly increased improvement in copper recovery and no statistical change in either the rougher or final copper concentrate grades for copper and gold.With the reduction in pH, there was a noticeable reduction in lime usage from 0.85 kg of lime per tonne of ore processed to 0.55 kg/t. This reduction in lime is equivalent to approximately $700,000 per annum at current production rates.CITATION:Kirkwood, B, Kinal, J, Siliezar, J and Sofatzis, H, 2013. Low pH trial in the Ernest Henry Mining copper rougher flotation circuit, in Proceedings MetPlant 2013 , pp 371-377 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By D Pilone

The Tyrrhenian micro-nodules, findable at low depths (200/600 m under s l) are a reasonable reserve of manganese. They can be easily and cheaply recovered but do not contain valuable metals as in the case of oceanic nodules. In this work a hydrometallurgical process for manganese recovery from Tyrrhenian nodules is presented. The studied treatment includes the following operations: magnetic enrichment, reducing leaching, leach liquor purification and electrowinning . The study shows that the most important step in the process is the preliminary manganese enrichment. It can be done directly on the platform reducing not only the transport cost, but also the residue mud in the metallurgical plant. The leaching parameters such as status and size of nodules, temperature, composition of leaching solution and S/L ratio have been investigated. After purifying the leach liquor by iron precipitation as ammonium jarosite , the conditions to electrowin manganese have been investigated. The yields of both manganese leaching and iron precipitation together with current efficiency and specific energy consumption in the electrowinning step are given.

Jan 1, 2000

During the construction of storage caverns, and during their lifetime if the use to which they are put so requires, it is necessary to provide adequate ventilation to ensure the safety and comfort of the underground workforce. An analysis of likely contaminants during construction has indicated that where a large facility is situated in a rock mass of even moderate temperature climatic conditions are likely to be the limiting factor during most of the mining operation and atmospheric pollution when blasting is undertaken. Possible options for improvement are increased air flow, cooling of intake air and reduction of the heat source by altering the number and type of haulage units employed in the cavern. Local solutions are an alternative approach where heat problems are confined to a few specific locations

Aug 1, 1994

By J. Alexis, G. Ye, E. Burström

Over the past twenty years the 3 MW DC arc furnace at MEFOS has been frequently used for development of new processes. These processes include recovery of valuable metals from slag, sludge and dust from steel and other metallurgical industry, treatment of ashes from power plant and incinerators, smelting reduction of minerals and zinc recovery from EAF dust. The process characteristics of the DC arc furnace operation in terms of: ? selective reduction, ? total reduction, ? process stability and flexibility, ? dust carry-over, ? thermodynamic conditions provided in the hot spot area, ? precision in composing slag products These are analysed and described in this paper based on technical results from selected test campaigns over the years and thermodynamic considerations. The electromagnetic properties of DC arcs beneath the electrode have been studied by CFD simulation. The calculated result enables us to understand some interesting technical phenomena observed. The heat balance has also been considered based on data obtained from test campaigns and heat balance calculation.

Jan 1, 2004

By J. Engels

CODELCO is considering the implementation of high-density tailings management at the Chuquicamata mine in northern Chile for its long term disposal plan. To achieve this, CODELCO commissioned the design, construction, and operation of a 70 t/d pilot plant, fed by existing tailings. The testing programme was completed in May 2011, and consisted of laboratory rheological and characterization assessments, pipe loop testing, beaching trials, and analyses of deposition behaviour for solid contents ranging from 57?68% (w/w). This paper describes the characteristics of the pilot plant, the testing programme, the beach trial analyses, and the resulting beach profile predictions based on the stream power theory. CODELCO also used other predictive beach slope methods, such as the equilibrium slope concept, which are not discussed in this paper. The final beach profile for design will be selected after an expert analysis of all methods has been completed.

Jan 1, 2012

By Brad Murray

Evaluating the performance of a shielded tunnel boring machine (TBM) can be difficult because the ground cannot be observed directly and in relation to the TBM attitude within the excavation. It is difficult to determine whether performance problems are caused by ground loading, steering issues, fine muck packing against the shield, or migration of annular grout around the shield. The Arrowhead Tunnels Project in Southern California uses strain gauges on its shielded hard rock TBMs to detect shield strains early and correlate them with tunneling conditions, thereby increasing the chances that problems will be correctly diagnosed and addressed to optimize TBM performance. The frequent automatic measurement of shield strain has also been valuable by confirming whether remedial methods used to free the machine after stoppages are effective. This paper discusses the qualitative interpretation of characteristic strain patterns on the Arrowhead Tunnels TBM shields and discusses installation details and special considerations for setting up a strain measurement system.

Jan 1, 2008

By F. Petkovich, M. P. Sudbury

Development of a new method of treating flotation concentrates for the preparation of feed suitable for direct charging to blast furnaces or converters is described. The method takes advantage of the fact that pyrrhotite contained in the concentrates can be made to undergo exothermic reactions which, under properly controlled conditions, result information of oxidation products that serve to cement the concentrate particles together. Thus green concentrates either in the form of pellets or briquettes containing 5 to 8 pct moisture not only were hardened, but also completely dried autogenously by continuous countercu,vrent shaft treatment with air. The process was developed through pilot plant operations ranging from 35 1b per hr to 2.5 tph, culminating in products evaluation tests on a railway-car scale. Falconbridge Nickel Mines Ltd., Falconbridge, Ont., have practised sintering, on a travelling grate machine, for many years to prepare a pyr-rhotite-bearing Cu-Ni sulfide flotation concentrate for blast furnace smelting. In recent years the development of new mines, and the construction of concentration plants some 40 miles from the smelter has increased the quantity of concentrate shipped, and encouraged the search for a method of producing dry, hard pellets or briquettes suitable for direct charging to a blast furnace or converter, and capable of withstanding considerable handling. The cementing properties of pyrrhotite oxidation products were discovered during a search for a suitable agglomeration method for sulfide concentrates, and were exploited in a process subsequently developed for autogenously drying and hardening pellets and briquettes of pyrrhotite-bearing Cu-Ni sulfide flotation concentrate. EARLY TEST WORK The production of hard, dry pellets of concentrate filter cake was attempted in the drying plant of one of the new concentrators. While soft pellets were produced containing 5 pct moisture, attempts at further drying resulted in disintegration of the pellets and intolerable dusting. The plant therefore was controlled to produce a concentrate containing about 6 pct moisture. The partially dried concentrate, which was shipped to Falconbridge for sintering, tended to heat spontaneously in transit. An at- tempt to briquette the moist concentrate at Falconbridge, in a plant incorporating a muller, a 20-in. roll briquetting press, and a steam-heated travelling grate oven, was more successful, although the equipment corroded rapidly due to the acid nature of the concentrate after spontaneous heating had occurred. LABORATORY STUDIES OF SPONTANEOUS HEATING OF CONCENTRATE The spontaneous heating of partially dried concentrate was studied in the laboratory. Moist concen-

Jan 1, 1961

By Steve Kral

As the current boom in the global mining industry rumbles on, mining companies have had to step up their efforts to replace mined reserves. Many of the majors are replacing and adding to their reserves and resources through acquisitions. This situation has allowed junior mining and exploration companies to do what they do best. They have been re-examining once uneconomic gold, copper and other metals properties with an eye to partnering with a major to develop them. And mines that have been closed for years due to poor economics are being given another look.

Jan 1, 2006

By B Xiao, J Yang, H Chen

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Tuwu-Yandong Cu deposit, located in the East Tianshan mountains in the eastern section of the Central Asian Orogenic Belt, is the largest and economically most important porphyry Cu deposit in Xinjiang, China. It contains ~3 Mt of copper at an average grade of 0.46 per cent Cu and 0.2 g/t Au, with significant amounts of Mo and Ag. The deposit is mainly hosted in the Carboniferous Qi’eshan Group and plagiogranite porphyry, and is controlled by faults that are east–west-, north-west- and north-east-trending. Ore minerals in the Tuwu-Yandong deposit are dominated by pyrite, chalcopyrite and molybdenite, with minor bornite, chalcocite, magnetite, sphalerite and galena. Gangue minerals are mainly composed of quartz, sericite, chlorite, epidote, anhydrite, gypsum, muscovite, biotite, phosphorite, sphene, dolomite, actinolite, barite, albite and calcite. Based on the megascopic and microscopic textural relationships and mineral assemblages, five stages of hydrothermal alteration and hypogene mineralisation are recognized in the Tuwu-Yandong Cu deposit: the potassic stage, propylitic stage, phyllic stage, late veins stage and supergene stage. Most of the copper was deposited during the phyllic stage, along with less molybdenite.CITATION:Xiao, B, Chen, H, Wang, Y and Yang, J, 2015. Geology, mineralisation and alteration of the Tuwu-Yandong porphyry Cu deposit, north-west China, in Proceedings PACRIM 2015 Congress, pp 641–644 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015