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By Kenneth M. Maas

The Bureau of Mines inventoried the land in southwestern Alaska to classify ownership and availability and compared this land with known mineral terranes and mineral deposits. This report discusses and quantifies the potential for favorable location of mining claims for metalliferous (locatable) mineral deposits. Of the nearly 24 million acres that constitute the study area, approximately 3.6 million acres or 17% are available for mineral location, 3.4 million acres or 14% are available with restrictions, and 17 million acres or 71% are unavailable. Mineral terranes are known to underlie about 7.8 million acres or 33% of the study area; 3 million acres or 38% occur on land available for mineral location, 1.3 million acres or 17% occur on land available with restrictions, and 3.5 million acres or 45% occur on unavailable land. The State of Alaska has opened over 91 % of its land in the study area to mineral location; in comparison, the Federal Government allows mineral location on 0.07% of the land under its jurisdiction. There are 117 known mineral deposits or occurrences within the study area, including 77 lode deposits and 40 placer deposits. Of the 41 lode deposits occurring within a mineral terrane, 2 occur on available land.

Jan 1, 1988

By L. Hales

Neural networks are a generalized, multivariable non-linear modeling technique that can be used to model mineral processing operations. Neural networks will be described as will their use in modeling column flotation. Optimization of column flotation will be explored and discussed by using the neural network column models.

Jan 1, 1996

By Maurilio Pereira Gomes

The aim of this work was to heat treat and characterize sintered valve seat inserts (VSI). The powder metallurgy route was the only way found to substitute cobalt and lead, used in the VSI original alloy, due to their high cost and toxicological effect, respectively. The studied VSI was obtained with AISI M2 high-speed steel powder mixed with iron powder and other additives such as manganese sulphide, graphite, zinc stearate, carbides and copper, which was added by metallic infiltration. All the VSI were air quenched and double tempered, for one hour each, at seven different equidistantly temperatures, ranging from 100 °C up to 700 °C. The physical and mechanical properties were evaluated by means of the VSI apparent density, apparent hardness and crush radial strength. The chemical composition was determined through gas analysis, for the light elements such as carbon and sulfur, and energy dispersive X-ray fluorescence spectrometry for other elements. Microstructural characterization was performed with the support of scanning electron microscopy and energy dispersive spectroscopy. Regarding the VSI final application, the best results were achieved with the inserts air quenched and double tempered at 600 °C.

Oct 30, 2017

By C. Opoku-Ware, M. Kukay, P. Conrad, F. Inkoom, R. Pal

Researchers at Montana Tech are investigating the potential for developing trees tolerable to degraded un-reclaimed mine site tailings and soils as a solution to re-establishing long-term tree growth on those sites. This project involves growing tree seedlings from seeds planted in the degraded mine tailings and soils in which they will eventually be planted. The outcome of the project is expected to lead to a successful solution for re-establishing tree growth in degraded tailings and soils in Butte, Montana with minimal post-planting human intervention. Work conducted on the project to date has shown successful growth of seedlings in degraded tailings and soils. INTRODUCTION In an effort to improve Butte Area One natural resources, this research project is working to help restore tree growth in the Butte Priority Soils Operable Unit Boundary (BPSOU) (Opoku-Ware, et al 2018). Research by Blicker, et al (2003) found that, the BPSOU, which is part of the Silver Bow Creek/Butte Area National Priorities List (Superfund) Site within and near Butte, Montana has multiple historic mining sites situated entirely within the urban setting of Butte. Mine wastes and mill tailings, accumulated from over 100 years of gold, silver, and especially copper mining are dispersed throughout Butte, posing health risks to human and environmental receptors. Stabilization of tailings sites is needed to control fugitive dust, prevent run-off of toxic material resulting in subsequent sediment deposition in streams, reducing the volume of water seepage through acidic and heavy metal contaminated material, and improving land productivity and aesthetic values (Watkin and Watkin, 1982). If successful, the project will help restore water quality and maintain stream flow in Silver Bow Creek where it flows through Butte Area One. Trees native to Butte are being grown to seedlings in a greenhouse located on Montana Tech’s campus which will be planted in degraded soils located within the BPSOU. Growing trees is expected to help restore vegetative ground cover within the watershed contributing to stream flow in Silver Bow Creek. The trees will prevent soil and tailings from eroding and being deposited in Silver Bow Creek where they could degrade water quality and choke stream flow. The project combines research with tree seedling growth to provide a resource for Butte that could produce thousands of tree seedlings each year adapted to the harsh climate, soil, and tailings conditions that exist in the BPSOU where they will grow. It is anticipated that the trees developed by the project will have the capability for long-term survival and growth because they will be germinated and grown into seedlings in the degraded soils and tailings collected from the BPSOU where they will be planted. Soils and tailings collected for the project have been evaluated to determine if they lack nutrients or contain substances potentially toxic to the long-term growth and survival of the trees. Toxic levels of metals, high concentrations of soluble salts, extremes in pH, nutrient deficiencies and imbalances, surface crusting, high bulk density, low infiltration rates, high surface temperatures, low cation exchange capacity, restricted microbial activity, low water retention, harsh climatic conditions and surface particle movement are some of the traits of mine tailings sites that restrict revegetation efforts (Barth, 1986).

Jan 1, 2019

By P Clark

This paper discusses the challenges, solutions and lessons learnt as tunnelling work continues on the Melbourne Main Sewer Replacement (MMSR) project.The MMSR project is a $220 million dollar project for the Melbourne Water Corporation. It involves the construction of approximately 4.2 km of new sewer from the southern fringe of the CBD through the inner metropolitan suburbs of Port Melbourne and South Melbourne.Of the 4.2 km of sewer currently in construction approximately 2.2 km will be constructed using a 2.95 m diameter Lovat EPB tunnel boring machine (TBM) with approximately 1.9 km of small diameter (300 to 600 mm) reticulation sewers constructed using trenchless techniques.These sewers are being constructed in a dense urban environment, which means that the tunnels and shafts are often in close proximity to buildings and structures. The underground constructionof the sewer is further complicated by the variable geology of the ancient Yarra River delta which includes weathered basalts, the infamous Coode island silt formation and fine loose sands.Some of the key challenges and lessons learnt so far during construction include:· steering and alignment control of the TBM through very soft silt with little residual strength,· development and refinement of a monitoring and alarm system for leaving the machine dormant on a day works only project,· control and measurement of tunnel lining defl ection during ring build and grouting,· prediction and monitoring of surface settlements during tunnel excavation,· improved understanding of the geology and hydrogeology at this previously unchartered area of Melbourne,· consolidation settlement due to dewatering at shafts required careful construction controls, and· ground support and excavation in close proximity to the existing 110 year old sewer which requiredvery detailed risk control measures.

Mar 8, 2011

By Andrzej M. Wala

A knowledge of the friction factor (K-factor) is necessary in planning and designing mine ventilation systems for least cost and highest effectiveness. The friction factor used must be accurate and reliable for correct estimation of airway resistances. At present, the friction factors are determined by using tables of published values. These values were established principally for metal-mine openings having small effective areas. This presents a problem to the ventilation design engineer whose responsibilities center around the design of effective ventilation systems for large room-and- pillar mechanized underground coal mines. Friction factors selected from these tables could be excessively conservative for large scale room-and- pillar operations. With only limited data on the K-factor (which are considerably site dependent) for Kentucky's coal mines and for all the above mentioned reasons, it was concluded that there is a need for field investigations to determine these values in-situ for existing mining conditions in Kentucky. The author describe the study carried out in ten coal mines located in eastern and western Kentucky and present the results of the investigation in both tabular and graphical form.

Jan 1, 1991

By Betty J. Laswell, Gerald W. Laswell

Rotary drilling in modern open-pit mining is usually considered the lead phase which not only establishes the production rates but frequently limits them. From this viewpoint alone, the drilling phase must be maximized. The drill phase is the step that permits all the other operational phases to function within their design limits. This means that, in most cases, the drill is literally run to destruction to ensure that the shovel will be able to smoothly and consistently load a manageably size muck, the haul trucks can carry a balanced load without having a boulder dropped through the bed, and the crusher can devour constant rock size.

Jan 8, 1978

By D. A. Sloan

"THE FIRST COMMENTATOR that I will call on is Mr. W. G. (Bill) Brissenden, Vice-President, Mines, Noranda Mines Ltd. Bill, would you care to comment.W. G. BRISSENDEN ...Mr. Chairman, Ladies and Gentlemen, I spent some time reading the four papers that were presented here, yesterday evening, and decided that the four to six minutes that I had been allotted for this afternoon were going to be pretty tough to meet. It's a very big subject and I just hope that I will be able to stay within my time limit. As has been so aptly demonstrated by the members of our panel here this afternoon young men in growing numbers continue to be attracted to careers in the mineral industry, especially to careers in mining engineering. Now from 80 the point of view that the profession may have regained its status this is indeed welcome news. However, perhaps all of the members seem to have the suspicion that the number of mining engineers that the industry can absorb is a much lower figure than previously forecast. It is said that technical school graduates are now occupying some of the jobs once considered the private preserve of the mining engineer and also that mining engineering undergraduates are having trouble locating summer employment. If these interpretations of mine are correct then we are now confronted not only with our old dilemma - whither the mining engineer - but also with an urgent need to solve it. We cannot allow our profession to become once again an undesirable one in the eyes of our youth because if we permit such a thing to happen a second time the profession may never recover."

Jan 1, 1972

"NI 43-101 is a rule that governs how issuers disclose scientific and technical information about mineral projects to the public in Canada. The disclosure standards apply to oral statements as well as written documents and websites. NI 43-101 does not apply to disclosure concerning petroleum, natural gas, bituminous sands or shales, groundwater, or coal be methane. NI 43-101 first came into force on Feb. 1, 2001 and was revised in December 30, 2005. As a “National Instrument”, the law has been passed in each provincial and territorial legislature across Canada.“PART 1 DEFINITIONS AND INTERPRETATION 1.1 Definitions - In this Instrument “adjacent property” means a property(a) in which the issuer does not have an interest;(b) that has a boundary reasonablyproximate to the propertybeing reported on; and (c) that has geological characteristics similar to those of the property being reported on; “data verification” means the process of confirming that data has been generated withproper procedures, has been accurately transcribed from the original source and is suitable to be used; “development property” means a property that is being prepared for mineral production and for which economic viability has been demonstrated by a feasibility study; “disclosure” means any oralstatement orwritten disclosure made by oron behalf of an issuer and intended to be, orreasonablylikely to be, made available to the public in a jurisdiction of Canada, whether or not filed under securitieslegislation, but does not include written disclosure that is made available to the public only by reason of having been filed with a government or agencyof government pursuant to a requirement of lawother than securities legislation; “early stage exploration property” means a property that has(a) no current mineral resources or mineral reserves defined; and (b) no drilling or trenching proposed; in a technical report being filed in a local jurisdiction; “exploration information” means geological, geophysical, geochemical, sampling, drilling, trenching, analytical testing,assaying, mineralogical, metallurgical and other similar information concerning a particular property that is derived fromactivities undertaken to locate, investigate, define or delineate a mineral prospect or mineral deposit; “feasibility study” means a comprehensive studyof a mineral deposit in which all geological, engineering, legal,operating, economic, social, environmental and other relevant factors are considered in sufficient detail that it could reasonably serve as the basis for a final decision by a financial institution to finance the development of the deposit for mineral production; “historical estimate” means an estimate of mineral resources or mineral reserves prepared prior to February 1, 2001;“IMMM Reporting Code” means the classification system and definitions of mineral resources and mineral reservesapproved by The Institution of Materials, Minerals, and Mining in the United Kingdom, as amended; “JORC Code”means the Australasian Code for Reporting of Mineral Resources and Ore Reserves prepared by the Joint Ore Reserves Committee of the Australasian Institute of Mining and Metallurgy, Australian Institute ofGeoscientists and Mineral Council of Australia, as amended; “mineral project” means any exploration, development or production activity, including a royalty interest or similarinterest in these activities, in respect of diamonds, natural solid inorganic material, or natural solid fossilized organic material including base and precious metals, coal, and industrial minerals;"

Jan 1, 2003

By Ashish Agarwal

For a correct evaluation of the performance of any process, it is important to reconcile the data gathered in the plant from the material balance point of view for all the streams flowing in and flowing out of the process unit. There are two main approaches to reconciliation of data, which involve minimization of the sum of the squares of: (i) the closure residuals and (ii) the component adjustments; both weighed with the estimated variances of the components. Though, these approaches have served us well, it has not been possible to ascertain if the reconciled values for various components and the split factors obtained using these approaches are truly the best estimates. In this paper, this aspect has been investigated by analyzing pseudo-experimental data of known error structure on size classification of particles in a hydrocyclone. Three types of basic error structures were considered for the measured component values: absolute error, relative error and chi-square error. The error structure was modified by adding a random component of error using normally distributed random numbers corresponding to zero mean and different levels of variance. By carrying out a large number of simulation experiments, it has been shown that in the presence of random errors, irrespective of the basic error structure of data, which is usually unknown, the chi-square error minimization criterion can be used to obtain most reliable results. Keywords: data reconciliation methods, chi-square error minimization

Sep 1, 2012

By J. Jorge, J. Mariño-Salguero, B. Álvarez-Rodriguez, J. M. Menéndez-Aguado, J. J. de Felipe

"This work focuses on the characterization of heat generation during dry fracture by direct impact of a tantalum ore. Moreover, an attempt was made to quantify the heat energy loss to the environment during the grinding process of a ball mill. The study was carried out using mineral samples from a Spanish mine that were characterized by measuring their density and specific heat. During the experiments, increases of temperature ranging from 5.9 to 7.3 °C after the fracturing process were observed. A numerical model was then applied to calculate temperature distributions through the mill wall. Three possible combinations of heat transfer coefficients were analyzed, from (1) Kapakyulu and Moys, (2) Duda and (3) the heat transfer laboratory of Universitat Politècnica de Catalunya. The models with the coefficients from Kapakyulu and Moys and the heat transfer laboratory of Universitat Politècnica de Catalunya were found to provide results that were in best agreement with the experimental data. IntroductionEvery year, several billion tons of metallic ores, minerals, cement and other solids used in the ceramic and chemical industries are subjected to size reduction in ball mills around the world. The U.S. Department of Energy (2005) reported that in the United States about 29 percent of the total energy used by the mining industry, or 0.4 percent of total U.S. energy consumption, is used in comminution. In Canada and Australia, comminution is responsible for about 2 percent and 1.5 percent of total energy use, respectively. In nonindustrialized countries where mining constitutes higher fractions of their industrial sectors, comminution costs represent a significant contribution to mine operating costs. The specific energy consumption values for the grinding of these materials typically range from 5 to 50 kWh/t. Thus, a significant amount of electrical energy is consumed in the ball mill grinding operation (Aguado et al., 2006; Gupta and Sharma, 2014). Grinding can represent up to 50 percent of the direct operating cost in a mineral processing plant, especially as comminution devices operate in highly inefficient ranges of 4 to 8 percent (Wang, Yang and Yu, 2012)."

Jan 1, 2017

Choosing the right valve for corrosive, abrasive slurry applications requires exacting analysis and a comprehensive understanding of the complete slurry process. Within the realm of flow control in abrasive and corrosive slurry applications, there is no room for a one-size-fits-all approach. To ensure minimal maintenance, maximum uptime and the lowest overall cost of ownership, the slurry processing toolbox must contain countless alloy and elastomeric pairings ? each carefully targeted to the particular process medium and conditions. This materials selection process is best tackled by turning to expert slurry application engineers and valve product managers who work closely with customers to specify the optimal valve for the given parameters. ?When plant operators and design engineers apply conventional valves in abrasive applications or use metal seated valves or simply apply the wrong valve for a particular flow control situation, it typically leads to rapid valve failure, the potential for hazardous leakage, unexpected shutdowns and costly downtime,? said Cal Cobb, valve products manager for Weir Minerals North America, manufacturer of Isogate slurry valves for service in mining, minerals processing and metallurgical environments.

Jan 1, 2011

By Jennings S. Cox

(Glen Summit Meeting, June, 1911.) THE following notes, prepared in 1908, as the result of a personal examination and extensive explorations under my direction in 1906, have been revised and greatly augmented after two subsequent visits and further explorations in 191.0. The hard iron-ores of the south coast of Oriente Province, in the island of Cuba, have been known for many years, in fact one mine has been in operation for more than 20 years ; but it is only within the past four years that the large mantle-deposits of brown ores of the north coast have attracted serious attention. A. C. Spencer 1 has described these ores in a paper, entitled Three Deposits of Iron Ore in Cuba, which refers to the Mayari, Moa, and Cubitas deposits. C. M. Weld,2 in a scholarly paper on The Residual Brown Iron-Ores of Cuba, has discussed the character and possible genesis of these deposits with particular reference to the Moa field, calling attention also to the Taco and Navas fields in addition to those described by Spencer. Descriptive articles with reference to the Mayari field, and a few words about the Moa deposit, have also appeared.3 It is the purpose of the present paper to give some account of the exploration of the Moa deposit and to call attention to its commercial importance. LOCATION. The Moa district is situated on the north coast of the . Province of Oriente, which is the most easterly province of the island of Cuba. It lies on the northern or seaward slope of 1 Bulletin No. 340, U. S. Geological Survey, pp. 318 to 329 (1908). 2 Trans., xl., 299 to 312 (1910). 3 Iron Age, vol. lxxx., No. 7, pp. 421 to 426 (Aug. 15, 1907), and vol. lxxxi., No. 15, pp. 1149 to 1157 (April 9, 1908).

Mar 1, 1911

By Jose Luis Pineda Villarreal

New technologies emerge every day with practical applications for open pit mining. For every operation, managers need to understand the best way to increase efficiency in drilling, blasting, fragmentation and hauling routes.

Jan 1, 2018

By Jaroslav Horskoý, Miroslav Raudenský, Bogdan Filipic, Božidar Sader

This paper describes main elements and practical use of the computational system for automated setting of optimized casting conditions in the continuous casting of steel. The system consists of the heat transfer model of the process, empirical metallurgical criteria, and optimization algorithm. The physical model of the, strand temperature distribution relies on the classical Bennon-Incropera mixture continuum formulation for the convective-diffusive heat transport. Fluid flow effects are considered through enhanced thermal conductivity of the liquid phase. The model is solved by the operator-splitting Crank-Nicolson finite volume version of the Voller-Swaminathan scheme. The solution procedure is coupled with the IDS solidification analysis package. Boundary conditions for the strand cooling rely on combination of the generic and plant-specific mold, spray, and roll heat transfer coefficients ' by coping the effects of the casting speed, casting temperature, casting powder, mold oscillation mode, steel grade, water or air-mist spray type, running water, trapped water on the rolls, and radiation. The caster safety and productivity and the quality of the strand are related to nine empirical metallurgical criteria. The criteria ensure the caster safety and economy as well limit the internal, longitudinal, and transversal surface cracking possibility. The problem of finding optimum casting parameter values is stated as a minimization problem based on the analytical form of the cooling criteria evaluated from the steady-state temperature distribution of the strand. To solve the optimization problem, a genetic algorithm is employed. The algorithm explores process parameters settings heuristically by applying the principles of biological evolution. It starts with a random set of solutions and iteratively improves them through selection and variation. Solutions are evaluated by running the heat transfer model of the process and extracting the values of the empirical metallurgical criteria.

Jan 1, 2000

By Jeroen van Eldert, Daniel Johansson, Henrik Ittner, Håkan Schunnesson

"Numerous aspects of underground construction, from structural stability to construction costs, depended on the tunnel quality, including blast damage and the Excavation Damage Zone. Accurately quantifying the extent and severity of damaged rock is a problem. Recent technical developments in the field of Measurement While Drilling (MWD), including software for on-board logging and on-site analysis, have shown potential for rock-mass characterization. Ground Penetrating Radar (GPR) and P-wave velocity measurement have also improved and show similar potential. This paper explores the use of MWD, GPR and P-wave velocity measurements and uses them in techniques for excavation damage characterization and prediction. The paper is based on data collected from a small underground waste-collection site in central Stockholm, Sweden. The data is correlated against rock-mass characteristics and their responses are evaluated. Results indicate potential for excavation damage characterization for all tested techniques, which could minimize blasting damage and improve the over-all tunnel quality. 1 INTRODUCTION During underground excavation the rock mass is influenced in many ways. The Excavation Damage Zone (EDZ) is a result of these influences. The EDZ can be defined by an irreversible change in rock mass properties, for example increased permeability. EDZ is influenced by the excavation method, the rock mass properties and the in-situ stresses in the area of the tunneling. Since the 1990s research has been done on the EDZ by Emsley et al. (1997), Christiansson et al. (2005), Olsson et al. (2009), Ouchterlony et al. (2009), Ittner et al. (2014), and Siren et al. (2015). Based on past literature the EDZ have in this paper been separated in the following subzones: 1. Failure Zone or over-break is the area outside the planned tunnel profile, including the Look-Out and hole deviation. This zone consists of fracture networks (both natural and blasting-induced), that caused rock fall-outs. The extent of the over-break can be determined by volumetric scanning and photogrammetry and the half cast factor can be used as a damage indicator. 2. The Damaged Zone is split into three parts and but the quantity and depth of damage is difficult to measure. Although it can be visualized by sawing of rock slices in the tunnel wall (Olsson et al. 2009), diamond coring (DC) or P-wave velocity reduction (Jern 2001): a. Inner Damage Zone (Crush Zone): It is located directly around the drill hole, and is caused by the shock-wave energy of the detonation. The micro fractures in the Crush Zone produce a white-wash (rock dust) in the half cast. b. Transition Zone: This zone consists of micro fractures that connect and form macro fractures, both radially and parallel to the tunnel wall. The macro fractures are caused by the gas expansion during the detonation of the explosive; it increases the pressure in the (micro) fractures and creates the macro fractures. Seismic reflection, rock slicing and core drilling can be used for the examination. c. Progressing Zone: In this zone the existing radial fractures propagate due to the increase gas pressure inside these macro fractures. Examination methods are seismic reflection, rock slicing and core drilling. In addition, the Peak Particle Velocity (vibrations) could be used to estimate the depth (Tesarik et al. 2011)."

Jan 1, 2016

By Robert L. Lagace

The objective of this task was to perform theoretical analyses related to identifying and increasing the understanding of wireless propagation mechanisms in mines, and for predicting the performance ranges and limitations of proposed systems. This was to be achieved by building on and extending previous ADL work* and utilizing experimental data as they became available in the radio frequency bands of interest. B. TASKS Theoretical radio wave propagation investigations undertaken on this task centered on three areas. The first area dealt with extending previous UHF wireless propagation results*: to estimate the losses caused by the presence of haulage vehicles such as trains in coal mine tunnels; to estimate the propagation losses and wireless communication ranges expected along a longwall coal face tunnel; and to assess the applicability of previous analytical approximations to tunnels having reduced crossectional dimensions, such as those found in low coal and in the presence of haulage vehicles. The second area dealt with the development of a suitable propagation model to adequately explain the unexpected, highly favorable LF to MF band wireless radio wave propagation behavior experimentally observed in Consolidation Coal Co.'s Ireland mine. The third area dealt with the formulation of a model for evaluating the overall system transfer function and transmitter requirements for a hoist shaft LF communications system, taking into account the hoist rope/shaft transmission line characteristics, the cage and sheave wheel line terminations, the signal inductive couplers, and hoist shaft signal and noise data.

Jan 1, 1975

By T. Qiu

"The purpose of this study is to investigate the effect of the dosage of sodium hypochlorite as activator on the flotations of depressed marmatite and depressed chalcopyrite, with a focus on activation-flotation kinetics. Four flotation kinetic models were applied to test data using 1stOpt statistical analysis software to estimate the relationships between the maximum flotation recovery rates for the depressed marmatite and depressed chalcopyrite, the flotation rate constants and the sodium hypochlorite dosages. Within the range investigated, the highest flotation performances of depressed marmatite and depressed chalcopyrite were obtained at 2.5 mL/L sodium hypochlorite with zinc recovery rate of 93.8 percent and 3 mL/L sodium hypochlorite with copper recovery rate of 94.6 percent, respectively, after four minutes of flotation. A second-order model with rectangular distribution of flotabilities gave the best fit to test data collected at various sodium hypochlorite dosages. For the highest flotation performances of depressed marmatite and depressed chalcopyrite, the respective equations of their flotation models were derived and presented.IntroductionCyanidation tailings are the solid residues generated by gold plants that use cyanide to extract gold (Lv, Ding and Qian, 2015; Zhang, Li and Yu, 2013). Because of increasing demand for gold, the Chinese gold industry has developed rapidly, with production amounting to 451.799 tons in 2014, an increase of 5.5 percent from 2013. Chinese gold production has been the highest in the world for eight consecutive years. As a result, more than 2.45 million tons of cyanidation tailings are estimated to be discharged into tailings ponds every year (Li et al., 2010; Lv, Ding and Qian et al., 2015; Wang et al., 2015; Zhang, Li and Yu, 2013; Zhang, Li and Yu, 2012), and approximately 300 million tons of cyanide tailings are stockpiled in China, with the potential to cause serious environmental pollution as well as death to wildlife (Adams and Lloyd, 2008; Donato et al., 2007; Hewitt, Breuer and Jeffery, 2012; Velasquez-Lopez et al., 2011; Stephen et al., 2009; Zagury, Oudjehani and Deschenes, 2004). Concerns over cyanidation tailings are not exclusively environmental but also economic, as tailings occupy considerable land area, and tailings storage facilities increase the production costs of gold enterprises (Donato et al., 2007). Tailings often contain other valuable metals such as zinc, lead and copper. For example, the cyanidation tailings of Gaoyao Hetai Gold Plant in Guangdong Province contain 2.5 percent copper (Cu), 0.31 percent lead (Pb), 0.23 percent zinc (Zn) and 15.36 percent iron (Fe) (Shi, 2008), and the tailings of Tianshui Gold Plant in Gansu Province contain 1.94 percent Cu, 5.96 percent Pb, 0.27 percent Zn and 24.62 percent Fe. Cyanidation tailings have therefore been increasingly viewed as a secondary resource rather than waste."

Jan 1, 2016

By D Mather, H R. Asche

"In the civil tunnelling field, the use of tunnel boring machines (TBM) has now overtaken the use of conventional excavation methods (drill and blast / roadheader). This is due to a number of reasons, including the increasing availability and reliability of TBMs, the ability to deal with a wider range of face conditions, and the reduced excavation cost that TBMs can bring.Mining companies have spearheaded the advances in shaft boring by mechanised means, both in blind and raise boring. However, mining companies have been slower to adopt mechanised tunnelling.When contrasted with a conventional mining contract, there are good reasons why TBMs in mining applications are relatively rare. A conventional decline contract may have very little geotechnical information. The decline alignment can be subject to change as the tunnelling progresses. The infrastructure requirements are less for a conventional decline, and the sunk cost prior to excavation commencing is lower. Contract documents can be very simple.The history of TBM use in mining is reviewed and lessons are described. From the case histories and lessons learnt, the paper identifies ways that mining companies can maximise the potential benefit of TBM technology.We believe that despite the additional requirements for TBM declines, the cost and time advantage to mining companies is very attractive. The challenge is to recognise and to meet the requirements for success in a TBM drive to achieve the advantages of: faster advance rates reduced rock damage/overbreak reduced support requirements uniform muck characteristics greater personnel safety.From the case histories and lessons learnt, the paper identifies ways that mining companies can maximise the potential benefit of TBM technology.CITATION:Asche, H R and Mather, D, 2014. Use of ?tunnel boring machines in the mine environment, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 655–662 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 17, 2014

By J Gould, T Elkington

Mine operation strategies are commonly optimised with a net present value (NPV) maximisation objective. There are well known properties of a typical mining project optimised for NPV, including high production rates and declining cut-off grade schedules. In practice, however, frequently there are operations that diverge from such NPV-maximising properties. Although a range of reasons for this can be at play, one possible explanation is that operators intuitively adjust their strategies to compensate for the flaws inherent to NPV maximisation. In particular, NPV analysis does not reflect the benefits of managerial flexibility inherent in a mining plan. Real options valuation (ROV) is an alternative approach that addresses this issue. We compare the properties of NPV and ROV optimisation solutions generated for the same scenario. Our simple case study demonstrates that the presence of real operating options in the optimisation model not only entails increased project value as expected, but also tends to encourage lower processing capacity (with lower associated capital cost), higher cut-off grades and greater use of stockpiles.CITATION:Elkington, T and Gould, J, 2012. Real option value optimisation, in Proceedings Project Evaluation 2012 , pp 35-40 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012