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By S Cossfo Torres

Minera PenmontÆs gold mine, La Herradura, is located at the northwestern Mexican state of Sonora and consists of an open pit mine and heap leaching facility for the recovery of gold. The production began in July 1998, and today La Herradura produces about 200 000 oz of gold per year. Standard sampling and assaying protocols were established during exploration based on heterogeneity tests. However, at deeper zones of the pit, coarse gold became evident and it was necessary to develop a new sampling protocol in order to minimise the fundamental error and improve the metallurgical accounting. This new sampling protocol requires cyanide leaching the whole pulverised sample from the blasthole, assaying pregnant solution and fire assaying 50 g of tailings. A sampling study was performed on 195 blasthole samples analysing gold under the standard and new protocols. The new protocol demonstrated that the original one underestimated gold grade by approximately 27 per cent, with impacts on ore misclassification and metallurgical accounting. According to the ore grade control system, mineral with gold grade above 0.35 g/t was sent to the leach pad and mineral with lower grade was classified as waste. Based on the sampling study, it was decided to classify a low-grade ore with gold assay between 0.20 and 0.35 g/t which was stored for future treatment under better gold prices or should mine production decrease. These two conditions were present during 2005 and 2006, when about 3.5 Mt of low-grade ore were leached.

Jan 1, 2008

By B. Krysa, J. Qiu

The zinc pressure leach plant at HBM&S's operations is now in its fifteenth year of operation. Current pressure leach operation is steady at a concentrate processing rate of around 26.5 tonnes per hour. A new cellhouse with a design capacity of 124,000 tonnes per annum and the capability of expansion of up to 154,000 tonnes per annum was commissioned in July 2001. The potential to expand the capacity of the pressure leach circuit and associated processes, as well as the purification circuit and casting plant, to meet the maximum capacity of the cellhouse has been investigated. This paper reviews current operation of the zinc plant, as well as the possibility of a capacity increase without major process modifications or major capital expenditures.

Jan 1, 2008

By N. Mangesana

The effect of high solids concentration and coarse particle sizes (d50 ranges 90?300 µm) on the viscosity of a suspension of water and silica sand was investigated. The experiments were designed to include conditions that have been tested by other authors and those encountered in the operation of tumbling mills. The rheological data was measured using a tube rheometer with operating pseudo shear rates of up to 1500 s-1. The rheograms obtained depicted dilatant behaviour. The Otswald-de Waele, Bingham, Herschel-Buckley and Casson models were fitted to the experimental data. The Herschel-Buckely model, which approximates the yield point and gives an indication of the shear thinning or shear thickening behaviour of the suspension, was found to provide the best description of the flow curves for all slurries. The Herschel-Buckely model was then used to determine the apparent viscosity of all the tests. The apparent viscosity and yield stress increased with solids concentration and particle size at the different pseudo shear rates. The increase in slurry viscosity with solids concentration was attributed to increased frequency of particle-particle interactions. The increase in slurry viscosity with particle size was attributed to increased inertial effects. At low shear rates the sand slurry exhibited shear thinning behaviour for all solids concentrations. At higher shear rates above 1000 s-1the high solids concentration suspensions exhibited a transition from shear thinning to a shear thickening behaviour.

Jan 1, 2008

By H Austrheim, A K. Engvik, A Putnis

How aqueous fluids move through rocks and minerals is a question of possible pathways and mechanisms. Existing pathways such as fractures and grain or mineral boundaries provide obvious channels for fluid movement. We show how minerals reactive in the presence of an interfacial fluid can be replaced by new product phases through a process of interface-coupled dissolution-reprecipitation. A resulting porosity in the new phase provides a new pathway for fluid movement and therefore mass transport through the mineral, which progressively reacts at a moving interface. Eventually fluids of new and changing composition can pass through originally solid minerals and move on further, taking remobilised elements with them, to be reprecipitated whenever the chemical and/or physical conditions allow. One such example is albitisation of rocks associated with mineralisation.

Jan 1, 2008

In order to realise seafloor massive sulfide (SMS) mining, the environmental baseline survey around targeted SMS mining areas and the creation of an environmental assessment technique suitable for quantifying the impacts of ocean floor mining are necessary. The targeted areas generally host large chemosynthetic communities in association with active hydrothermal venting. The ecosystem structure around the chemosynthetic communities has not been clarified yet in macro-scale or quantitatively. The systematic approach and plan for the baseline survey and the environmental assessmentÆs basic studies are introduced. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

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 Madan M. Singh

This section is unique to the Handbook in that it is the only section that deals with underground excavations for nonmining purposes. The editors were of the opinion that the section should be incorporated because the subject matter covered by the chapters is closely related to mining, and many mining engineers are currently involved in these activities. As we enter the decade of the 1990s activities in this category will increase, enhancing the relevance and utility of the material discussed. As the population increases, especially in metropolitan areas, the necessity to go underground will be greater. At the present time, not only are subsurface shopping malls and pedways connecting buildings becoming commonplace, but structures as diverse as the Civil and Mining Engineering Building on the University of Minnesota campus, a road-and-fleet maintenance facility in Multnomah County, OR, and even an ice cream parlor (Dairy Queen) in northern Wisconsin have been constructed underground. Placing utilities below the surface has numerous advantages and is now customary. Rapid transit and highways through tunnels in urban areas have been the norm for many years, but subterranean stormwater reservoirs, power plants, industrial warehouses, and food storage silos are relatively new innovations. The philosophy of underground defense installations is ancient, but their requirements and designs have trans-formed radically as technology advances. The use of under-ground space for disposition of wastes is modern, since it is recently that environmental concerns and waste disposal costs have assumed increased significance.

Jan 1, 2008

By J. P. Kirsch

This paper sets out to clearly identify all elements that make up an effective furnace feed system. These are outlined and the more common types of technology are listed. These technologies all play an important role in the final delivery of all feed materials to the furnace.

Jan 1, 2008

By G Newling

Zinifex Rosebery Mine is a lead-zinc underground mining operation located at the base of Mount Black, on the West Coast of Tasmania. Mining activities at the Rosebery Mine have been undertaken for over 100 years, and it has been operating in its current form for over 60 years. A large surface and underground exploration drilling program over the last 18 months has increased the mineÆs expected mine life from five to 12 years, with expectations that over the next 18 months as the program continues this will swell to 20 plus years. Zinifex Ltd secured Rosebery Mine in April 2004 and commissioned a detailed life-of-mine (LOM) study on all aspects of the operation. One of the most detailed sections of this report was on the state of the current ventilation system. It was identified in this report that for mining at the current depth of approximately 1100 m to continue a minimum 30 per cent increase in ventilation quantity was essential, as well as a likely requirement for a refrigerant cooling plant for each of the two deepest panels, the K and P lenses. It was identified that Zinifex did not have personnel with the expertise in underground refrigeration to manage and implement a project of this nature. A second report was commissioned with Bluhm Burton Engineering (BBE), a South African firm specialising in both surface and underground large-scale refrigeration plants. BBE concluded that two refrigeration plants were required to provide the necessary cooling power in the lower sections of the mine. In 2005, with BBE as technical consultants, Zinifex Rosebery Mine embarked on a project to commission two underground refrigeration units capable of lowering the wet bulb temperature at the decline face by four degrees centigrade. This paper is intended to give the reader an overview of: Rosebery Mine operations,Rosebery underground refrigeration project,technical difficulties associated with implementing an underground refrigeration system, andkey learnings to date.

Jan 1, 2008

By Anand Raman, Steve Dixon

"Industry practice for defining acid consumption is based on column tests. Freeport-McMoRan (FCX) has adopted a practice of leach operation using a defined pH or gpl acid in the raffinate based on the column test program. The acid consumption can be easily calculated using the leach operating parameters of SX-EW efficiency, lift height, bulk density, irrigation rate, primary leach cycle time, acid cure dose and acid concentration in the raffinate. The column leach test results and a column to heap efficiency factor are used to define the copper extraction. The maximum acid consumption will occur when zero acid is contained in the raffinate. The term Net Extracted Value (NEV) is to define the maximum extracted value relative to acid consumed.This paper presents the operating logic and method used to calculate acid consumption based on column tests and operating parameters.INTRODUCTIONIndustry practice for defining acid consumption is based on column tests. This may result in lower economic value if the tests are not designed to account for operating variables. A test program is described to assist in defining lift height and the influence of gangue on solution chemistry. A simple spreadsheet is presented that will use the leach operating parameters of SXEW efficiency, lift height, bulk density, irrigation rate, primary leach cycle time, acid cure dose and acid concentration in the raffinate to calculate the acid consumption for a proposed operation.A review of current leach operations solution chemistry will help to define acid consumption. This is recommended for all current leach operations.DISCUSSIONThe current practice at Freeport-McMoRan (FCX) is the use of column test results to define operating parameters. The monitoring of operational solution chemistry and copper production addresses any changes needed in operational parameters. This practice maximizes the value extracted from each tonne of ore leached."

Jan 1, 2008

By Anne Fagot

Because of the risk of corrosion caused by stray currents, steel foundations and steel sheet piling are generally prohibited in the vicinity of railway structures. Steel solutions are only accepted if they are shown to meet the required design working life and if this can be achieved at an acceptable cost compared to competing materials. The influence of stray currents on various steel sheet piling designs was studied using software initially dedicated to gas and pipeline industries and cathodic protection systems. It has been successfully adapted to model stray currents affecting steel sheet piling. Corrosion rates assessed using this modeling software were considerably lower than commonly expected. Zones of potential corrosion risk were identified; specific cost-effective countermeasures could be established. The developed software tool can help to optimize the design of piling solutions in the vicinity of DC railway power systems in terms of suitable countermeasures that meet structural reliability and cost requirements.

Jan 1, 2008

By Hugo E. Camargo

Noise Induced Hearing Loss is the most common occupational disease in the U.S. and of paramount importance in the mining industry. According to data for 2006 from the Mine Safety and Health Administration (MSHA), Continuous Miner operators accounted for 30.2% of underground mining equipment operators with noise doses exceeding the Permissible Exposure Limit (PEL). This figure becomes more significant considering that 49% of the 2006 national underground coal production was extracted using continuous mining methods. Thus, there is a clear need to reduce the sound radiated by Continuous Mining Machines. The first step towards efficient noise control of a Continuous Mining Machine requires identification of the various noise sources under controlled operating conditions. To this end, a 42-microphone phased array was used in conjunction with 4 reference microphones to sample the acoustic field of a machine in the Hemi-anechoic chamber of the Pittsburgh Research Laboratory. These data were processed using a frequency-domain beamforming algorithm to obtain acoustic maps of 5 sides of the machine. The focus of the test was on the conveyor noise since previous studies showed that operation of the conveyor is the most important contributor to the sound radiated by the machine. From the acoustic maps, the following potential areas for noise control were identified, and included: chain-tail-roller interaction, chain flight tip-side board interaction, and chain-upper deck interaction.

Jan 1, 2008

By Xiping Chen, Wangxing Li

"Spent potlining is unavoidable solid waste from aluminum smelters. About thirty kilograms spent potlining is discharged in China to produce per ton primary aluminum. Spent potlining has high level soluble fluorides and cyanides so that it brings heavy pollution to environment. It is prohibited to keep a large amount of spent potlining in open air because it will lead concentrated pollution to local soil and water source due to hydrated reactions between spent potlining and rain water/moisture in air. Landfill may solve pollution of spent potlining provisionally, but it is difficult to be accepted by aluminum smelters because of its high investment, troublesome monitoring and perennial maintenance. Detoxifying of spent potlining not only can remove deleterious fluorides and cyanides in SPL, but also can make fluorides in SPL recycle and return to aluminum electrolysis cells, at the same time benign SPL solid residue can be recycled and ready for cement production.IntroductionChina became the largest primary aluminum manufacturer in 2001. In the past few years, its aluminum output increased by twentyfive percent every year and reached 12.56 million metric tons in 2007. The whole world was very surprised and focused attention upon Chinese aluminum industry. It is more and more important to keep sustainable and steady development with the rapid development of Chinese economy. Aluminum industry is an important base industry and does a great contribution to Chinese economy. But aluminum industry is high energy-consumption and heavy-pollution industry. The government has paid more attention to aluminum industry in recent years. Nowadays the bothersome problem which counterworks Chinese aluminum industry is pollution from solid wastes. Main Solid wastes from aluminum industry are red mud from alumina refineries and spent potlining (short as SPL) from aluminum smelters. Spent potlining are waste lining materials from aluminum electrolysis cells. During production of aluminum, due to reactions between melted electrolyzer and pot lining as well as penetrating of fluorides into pot lining, newly-formed compounds inlayed in pot lining, destroyed the lining structure and brought pot lining cracking. Melt rushed out of lining cracks, cells have to be stopped running and ready for heavy repair. Cell life generally varies from 1500 to 2000 days. Spent potling is an unavoidable solid waste from aluminum industry."

Jan 1, 2008

By D. F. Machuca-Mory

A change of support model consists of a procedure to change a stationary histogram at a small data scale to represent a larger scale; typically a distribution of sample drill-hole data is changed to represent a chosen selective mining unit (SMU) scale. Most grade variables average arithmetically. Thus, the mean stays the same for different scales, and the variance changes according to well-established theory using average variogram values. The longstanding challenge has been to predict how the shape of the histogram changes. The discrete gaussian model is widely used because it appears reasonable and introduces few artifacts; there are no artificial minimum/maximum values and the target mean and variance are reproduced exactly. The resulting distribution shape, however, is strongly dependent on a multivariate gaussian distribution. The authors generalize the approach by taking advantage of a property of the isofactorial model, which allows one to specify where the random function falls on the spectrum between a low-entropy mosaic model and a maximum-entropy diffusion model. A measure of dissemination (MD) is computed using a ratio of the madogram and the variogram. The change of support algorithm is developed that uses a variable measure of dissemination (VMD) that is easily calculated and fit to data from the deposit. The resulting VMD change of support model is very flexible to represent different mineralization styles encountered in practice; global predictions of recoverable reserves are more accurate and decision-making is improved. A number of real examples are shown to demonstrate the approach.

Jan 1, 2008

By G. T. Lineberry

Underground mine development begins with the positive investment decision to mine and ends with the inception of full-scale exploitation. It incorporates all activities, personnel, and equipment required for creation of underground access to a mineral deposit. Because of the depletion of near-surface mineral resources, the reduced mobility of large surface mining equipment, increasingly stringent environmental constraints, and the introduction of promising innovations to rock penetration and rock excavating equipment (e.g., continuous miners, rock borers), under-ground mining is projected to account for an increased share of worldwide mineral production in the foreseeable future. Without proper engineering during the mine development phase, failure of the underground mining project is axiomatic. A frustration attendant to coverage of the complex area of underground mine development lies not only with the need for treatment of the many disparate specialties within the area but even with the lack of systematization of these specialties in what is recognized as a vital precursor to successful mining. Section17 offers insights into (1) the basic principles of the planning and design process, including baseline assessment, reserve determination, premine planning, and subsystem design (Chapter17.1); (2) equipment selection and sizing, with emphasis on exca-

Jan 1, 2008

By Michal Rehor, Vladimir Cablik, Peter Fecko, Tomas Lang

"1. Introduction The North-Bohemian Basin area is known for its largest Czech brown coal deposit. About 50% brown coal reserves have been exploited in the North-Bohemian Basin by the mining company of Severoceske doly, a.s. (North Bohemian Mines, j.s.c.) today. The opencast mining of brown coal naturally led to vast landscape damages. Therefore reclamation work has acquired great significance. The specific feature of Severoceske doly, a.s. mining is the fact that the mining has been realized in two geologically absolutely different localities. This fact demands even rather different methods of reclamations. The main problem at Doly Bilina localities is the occurrence of overburden rocks from the series of rocks of coal seams. These rocks are texturally light but large amounts of coal (cca 5 %) and sulphur (cca below 3 %) which makes the soil reaction extremely acid. If they appear on the surface of the dump, they create a phytotoxic area, reclamation of which requires special methods. Rocks from Doly Nastup Tusimice localities are more suitable to reclamation use, but texturally extremely heavy rocks with large fraction of physical clays appear there that can generate a sterile soil area. Their reclamation requirements are completely different from those on Doly Bilina phytotoxic areas. That is the reason of the application of some non – traditional restoration methods. This report briefly summarises the experience in application of fertilizable soils, power plant stabilizer, power plant ash and aerial sowing of charlock. The results are documented by the monitoring of the physical, mineralogical and pedological parameters of rocks in testing areas.2. Properties of Overburden Rocks in Opencast Mines Bilina and Libous The reclamation work methodology in the North Bohemian Basin is above all determined by the properties of overburden rocks which occur in the top horizon of the reclaimed sites. The research of the rocks reclamation properties dealt with four current mining localities in the central part of the basin. It concerned the Bilina and Libous mines. This chapter states the stratigraphic status properties of these sites with respect to reclamation availability. The total status of the area of interest is shown in the figure No. 1."

Jan 1, 2008

By K. Kavouridis

The energy and climate protection policy of European Union (EU), and its Member States adopted in 2007 bridges security of supply, environmental protection and competitiveness. The objectives of the EU energy and environmental strategy cover the foreseeable period till 2020. It assumes all sources of energy will be needed. The objectives for renewable and improved efficiency are ambitious; it must be established if they are also realistic. Coal can continue to make valuable contribution to the security of supply and low price of electricity, only with technologies allowing for drastic reduction of the CO2 emitted of its combustion. The aimed at -20% reduction of green-house gases (GHG) of EU-27 by 2020 is an objective limited in time and content. Europe produces less than 15% of global CO2 and this will be reduced to 10% in 2030. Emissions Trading (ET) is to remain the central instrument for CO2 management, especially in the power sector. ET scheme (ETS) or other mechanisms need designing to create an incentive for investment in higher efficiency and technologies and to Carbon Capture & Storage (CCS). The ETS as the climate protection instrument of the EU can become a heavy burden (high fuel and electricity prices, less security of supply) or it can create a climate for modernization of fossil fuel power plants. The suggestion in this paper of fuel-specific benchmark system for CO2 allocation after 2012 can combine the emission levels to be reached with a strong drive to invest, the necessary investment security, transparency and the principle of proportionality. A Benchmark System as recommended by coal industry could adapt to the different circumstances in the long term and comply with EU energy and environmental policy objectives.

Jan 1, 2008

By I. Dumitrescu

Since 1990, the entire Romanian mining industry has suffered a major restructuring, i.e. technical and economic. The large majority of the remaining active mines are these with a chance for economic comeback. This is also the case for the mines that belong to MINVEST Deva Company; most of the mines are closed, and are waiting to be reclaimed. The authors present the closing procedures of the former copper mining perimeters managed by MINVEST. It is well known that pollutants of concern for the environment must be monitored to obtain reliable information on the quality of ambient conditions and to minimize their impact on the environment. Consequently, the monitoring problems during the closing procedures will be presented.

Jan 1, 2008

By P B. Hills, R J. Walton

Geotechnical instrumentation has been implemented as a key step for monitoring and optimising an engineered mine design for managing seismicity at the Beaconsfield Gold Mine. Measurements of displacement, stress change, ground control element load and seismic response of the rock mass allow for back analysis and calibration of critical parameters for feedback into the engineering design loop. Instrument clusters are installed in strategic locations prior to the commencement of stoping in order to determine the nature of the response of the rock mass to stoping. A selection of instruments including instrumented cable bolts and rod extensometers, resistance wire extensometers, hollow inclusion stress cells, vibrating wire stress meters and resistance wire extensometers are used to gather data through a data logging system. The rate at which data is recorded is adjusted to provide more information during periods of anticipated rapid change such as around stope firings or during periods of high seismic activity, and less information during periods of anticipated quiescence. The twofold purpose of the instrumentation is to calibrate the numerical modelling output which forms the basis of the engineered mine design, and to provide an alert mechanism where the behaviour of the rock mass is not what was anticipated, or where the impact of that behaviour may compromise the integrity of the engineered ground control system. The paper describes the location of instrument clusters with respect to stoping, the type of instruments employed and the method of data acquisition. It provides examples of results obtained and illustrates the way in which that information is used to optimise the mine design and manage seismicity.

Jan 1, 2008

By Nourredine Menad, Christian Lucion, Maurice Save, Paul Hubaux, Solène Touzé

"The collection and treatment of WEEE has recently become mandatory in Europe and is now being organized. As the first step in current treatment processes is manual dismantling, we decided to investigate the development of an entirely automatic WEEE treatment procedure using physical separation techniques so as to limit manual sorting to the removal of hazardous components. Our approach was to test different wet and dry physical separation methods on bulk WEEE; i.e. gravity separation (jig and pneumatic table), electric conductivity separation (eddy currents), and particle shape separation (Lavodune classifier and vibrating helical conveyors). The results enabled us to determine a global treatment flowsheet of shredding, electromagnetic separation, eddy current separation, screening (2 mm), sink&float separation (d=1), and jigging. All the end products, except for the fine fraction, have possible recycling outlets. Batches of WEEE can thus be treated automatically once the problem of non-ferrous wires is resolved.IntroductionAccording to Ademe (French Agency for Environment and Energy Management; www.ademe.fr), France's annual production of WEEE is between 1.7 and 2.0 million tonnes. This waste, although of very varied composition, consists mainly of plastics and metals, and its collection and treatment has been mandatory in France since 2006; the modalities are gradually becoming organized. Existing treatment processes rely on a first step of manual dismantling which, though essential for removing dangerous components from the WEEE (e.g. batteries, cathode-ray tubes, ink cartridges, etc.), also includes separating out the decimetre-size plastic parts and metal parts. No fully automatic process has yet been developed for this type of waste. Moreover, the dismantling units in Europe are highly subsidized and call upon social workers. As this situation is not conceivable for the long-term, it is obviously important to develop entirely automatic WEEE-treatment technologies based on physical separation techniques. This would limit manual sorting to the removal of toxic components."

Jan 1, 2008