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By R. Roufail

Mineral liberation is accomplished by comminution and is the first step towards achieving successful downstream processes such as flotation or leaching. In metal mining, one of the most effective comminution methods that is used to grind particles below 10 microns is stirred milling. In this paper the study of particle breakage mode vs. mill operating parameters is addressed. Stirred mills' grinding action is mainly attrition, but operation can be manipulated to include breakage by compression or impact loading. Macro and micro analysis of particle breakage and grinding mechanisms are correlated. Macro analyses convey information that relates grinding mechanism to particle size and shape. It is speculated that the breakage mechanism in the horizontal stirred mills is massive fracture for the coarsest particles and attrition (abrasion) close to the grinding limit where the size reduction ratio approaches 1.0. For micro analysis, the particle breakage mode has a direct impact on fracture type either transgranular or intergranular. Intergranular particle breakage leads to higher mineral liberation compared to transgranular breakage. Similar minerals would have more homogeneous properties that convey a stronger bond compared to dissimilar, heterogeneous mineral bonds. Transgranular fracture requires higher energy than inter granular fracture; trans granular fracture toughness of pure single phase mineral is about 10-14 % higher than the intergranular fracture toughness. This communication presents the results of an investigation to assess how operating conditions can affect trans- vs. inter-granular breakage.

Jan 1, 2009

By Robert W. Leonardson

The Questa Molybdenite Mine provides a unique opportunity to study the geochemical dispersion of various hydrothermal events, utilizing drill hole analyses. Numerous post-ore factors have altered the primary ore-related geochemical dispersions to the present day configuration, e. g. dikes, faults, hydrothermal convection cells, and weathering. Due to the interaction of an andesitic volcanic pile with the silicic-alkalic generated volatiles, the geochemical haloes of the Goat Hill deposit demonstrate a marked divergence from the classic Climax-type molybdenite ore body. Certainly, however, the similarities to the Climax-type ore body are apparent as potassically-rich fluids have invaded the highly reactive country rock.

Jan 1, 1984

By R. W. Fountain, W. D. Forgeng

A new constitutional diagram is presented for the cobalt-rich end of the cobalt-titaniurn system. The modifications result from the presence of a new, intermediate, fcc phase, ?, the existence and homogeneity limits of which were established by metallo-graphic and X-ray studies of alloys containing from about 3 to 30 pct Ti. The precipitation of the ? phase from supersaturated solid solution was studied by hardness and electrical resistivity measzsrements, and two distinct stages in the process were observed. COBALT forms the base for a number of precipitation -hardenable alloy systems which may be divided into two distinct categories of practical interest, a) those hardened by intermetallic compounds and b) those hardened by carbide formation. The precipitation of intermetallic compounds from solid solution in cobalt-rich alloys has, however, received very little attention. Although the phase diagrams for some binary systems capable of precipitation have been determined,' there is an almost complete lack of data on the property changes associated with the precipitation, and even less information on the kinetics of the reactions or morphology of the products. More information is available on the precipitation of carbides because of the practical significance in superalloys. A survey of cobalt binary phase diagrams suggested that the cobalt-titanium alloys might provide interesting and useful precipitation-hardenable alloys. The equilibrium diagram as proposed by Wallbaum2 is shown in Fig. 1. Köster and wagner3 have indicated that the maximum solubility of titanium in cobalt is about 10 pct at the eutectic temperature (1135oC), and this decreases to about 7.2 pct at room temperature. The temperature of the allotropic transformation in cobalt is lowered by the addition of titanium, about 5 pct being sufficient to retain the high-temperature fcc modification to room temperature. Wallbaum and Witte 4,5 have indicated that the precipitating phase in alloys containing up to about 29 pct Ti is Co2Ti, a hexagonal Laves phase of the MgNi, type. With slightly higher titanium contents, they also report a cubic modification of Co2Ti of the MgCu2-type Laves phase. Duwez and Taylor6 confirmed the existence of the hexagonal (MgNi2) modification but not the cubic (MgCuz) modification of Co2Ti and suggested that existence of the cubic form may have resulted from impurities in Wallbaum's alloys. In their work on Laves-type phases, Elliott and Rostoker 7 reported the cubic modification of Co,Ti, but did not confirm the existence of the hexagonal modification. However, Dwight8 in a discussion of the work of Eliott and Rostoker again showed the existence of both modifications of Co2Ti, a result which was confirmed at that time by Elliott and Rostoker. As a result of a study on the iron-cobalt-titanium system, Köster and Gellers suggested the existence of a Co3Ti phase isomorphous with Fe3Ti. Witte and Wallbaum,' however, established the fact that no compound, Fe3Ti, exists in the iron-titanium system, and in a later publication, wallbaum2 stated that Kitster and Geller's reasoning was not valid, and no compound, Co3Ti, exists. This conclusion was later acknowledged by Köster.10 Preliminary experiments by the present authors to determine the precipitation-hardening characteristics of the cobalt-rich, cobalt-titanium alloys re-

Jan 1, 1960

By Premur V

In industry and power production and distribution large quantities of fine wastes are produced. These are above all fly ash and phosphogypsum. Attempts are made to use them as secondary raw materials in industry and construction. Since they contain dangerous and harmful components or are nonhomogeneous their direct application is limited so that they are treated as waste. This paper reports on tests conducted with the aim of agglomerating the mentioned fine industrial wastes by pelletisation. The aim of this resarch was to obtain agglomerated product suitable for handling, transport and dumping. At the same time efforts were made to incapsulate harmful components by producing pellets with protective shells. Next, pellets without binders and with different binders were produced. Strength, resistance to freezing and solubility of pellets were tested. All the fine industrial wastes under survey were found to be suitable for pelletisation. The utilisation of appropriate binders ensures pellet strength required for safe handling and ecologically sound deposition of pelleted Material.

Jan 1, 1993

By David M. R. Stone

Underground mining in the gold industry is gaining popularity in Nevada, and with it the use of cemented rockfill is becoming mainstream. Even with today?s high metal prices, however, mining companies are very sensitive to the margins they realize, and are constantly looking for ways to reduce costs or improve efficiencies. Given that the backfill is one of the largest cost centers in underground mining, mines are constantly under pressure to reduce backfill costs. This paper will present an overview of the factors that impact cemented rockfill quality in Nevada mines based on the authors many years of consulting experience. Cemented rockfill quality can be linked directly to binder consumption, hence programs aimed at improving quality generally result in lower binder costs, better performance in the fill (hence less dilution), and improved safety. The paper will conclude with the key elements of a comprehensive program of backfill quality assessments and backfill QA programs. Comparative laboratory and minesite data from a number of operating and proposed mines will be presented.

May 1, 2007

By C. F. Harris

Following the initial development of the zinc-lead blast furnace, efforts have been directed both at increasing the scope of the process and increasing the cash return. The paper reviews the process developments which enable the process to smelt efficiently a range of material which encompasses high-grade zinc sulphide concentrates. mixed concentrates, Waelz oxide, zinc ashes and other materials blended to give a furnace feed ranging from 25 to 65% zinc and from 1 to 25% lead, with a copper-lead ratio exceeding 1 to 8. The paper also reviews the process developments which have enabled the capacity of a furnace and condenser system of standard size to be boosted from 30,000 to 80,000 tonnes/annum. The benefits achieved are used as a justification for continuation of the development of the zinc-lead blast furnace. Predictions are made of the benefits expected from further developments.

Jan 1, 1979

By Collin Stewart

Bowie Resources maintains one of the most pro-active ground control programs in the U.S. mining industry today. Its guiding philosophy is that everyone in the organization, from the miners at the face all the way through the top management, are involved in ground control. Some of the unique elements of the Bowie ground control program include: ? Roof bolt operators log the stratigraphy of test holes in nearly every cut. These ?lithgraphs? are used by section foremen to determine the need for additional roof support, and they are entered into the geologic data base for use in geologic modeling and mapping. ? Underground core drilling is conducted to obtain data for CMRR and stability maps. ? Weekly ?Quality? meetings, involving mine management and technical staff, are held to ensure that ground control information is integrated into production operations. The paper will describe the program in detail, discussing the involvement of roof bolters, section foremen, surveyors, technical staff, and production managers. It will also show how the program has contributed to the mine planning process. Case histories of successful ground control interventions will be discussed.

Jan 1, 2006

By R. D. Doepker

The dissolution of metals from various metal-mine tailings has been studied through a series of submerged tailings batch tests at U.S. Bureau of Mines laboratories. Tailings selected for this study included both reactive (as determined by column leaching studies) and benign tailings. Metal mobilization in aerated (97 pct saturated with oxygen) samples appeared to be consistently greater than metal dissolution from stagnant (79 pct or 70 pct saturated with oxygen) waters. In the early weeks of the study, sulfate concentrations increased with solid-liquid contact time, while calcium dissolution remained nearly constant. Metal concentrations varied in relation to solid-liquid contact time and aeration. Leachate pH appeared to be nearly independent of solid-liquid contact time for basic tailings. Reactive tailings having both a submerged and a surface component demonstrated increased metal mobility.

Jan 1, 1990

By S Sandover, D Glenister

Alcoa World Alumina Australia is committed to sustainability principles as a basis of business success into the future. In March 2001, Alcoa Inc chairman Alain Belda announced a set of far-reaching environmental goals for the corporation, with the challenge that they should be achieved in ways that enhance economic and social performance, while substantially reducing environmental impact. Application of Cleaner Production methods is seen as the key to achieving these joint objectives. In Australia Alcoa has launched a co-ordinated effort to accelerate our application of Cleaner Production principles to delivering cost-effective in-process solutions to environmental issues. Our Western Australian Operations are a signatory to the WA Cleaner Production Statement, through which we provide a Cleaner Production Plan to the State Government on a voluntary basis. This paper describes in general terms AlcoaÆs goals, achievements and directions in applying Cleaner Production to enhance business performance in the economic, environmental and social dimensions. Quantification of the benefits and tracking of progress in quantitative terms is a key challenge for the future

Jan 1, 2002

By D. Berberick, G. Sturgis, M. Board, B. Strickland

"Hecla Limited is nearing completion of the Lucky Friday Mine No.4 shaft located in Mullan, ID. The shaft is collared at the 4940 level of the mine and will have a final mine level depth of 8620, or 9,590 feet below the surface. After reaching the 7400 mine level the shaft encountered ground deformation higher then allowed for in the design for a circular shaft excavation and concrete lining. This additional ground deformation required portions of the shaft concrete liner to be reinforced with frameless, steel liner plate. To eliminate the installation of the liner plate from the remaining shaft development, the design of the shaft excavation starting at the 7650 mine level was changed to an elliptical cross section based on the overall stress field orientation as well as the orientation of the structure of the host rock surrounding the shaft. The elliptical cross section was instrumented to confirm the shaft excavation and lining was performing as designed. This design change has allowed the shaft to continue to the planned 8620 mine level without the need to install liner plate in the shaft or change the overall functionality of the shaft or the Lucky Friday life of mine plan.INTRODUCTION Hecla’s Lucky Friday Mine is a deep, underground producer of silver, lead and zinc in the Coeur d’Alene mining district of northern Idaho (Figure 1). Primary access into the mine is via the Silver Shaft, a 5.5-m (18-ft) diameter, concrete lined shaft sunk to an original depth of 1,890-m (6,200-ft). Current production is from the Gold Hunter vein system, approximately 1,525-m (5,000-ft) northwest of the Silver Shaft.Lucky Friday’s #4-Shaft is a 5.5-m (18-ft) finished diameter, internal shaft, or winze, being sunk to the north of the Gold Hunter vein system, from the mine’s 4760 level, 1,743-m (5,720-ft) below the surface, to the 8620 level, 2,923-m (9,590-ft) below the surface. The shaft is designed to provide access to the deep, high-grade zones of the Gold Hunter in order to increase the mine’s production and operational life. Design and engineering began in 2006, with construction starting in the fourth quarter of 2009."

Jan 1, 2016

By Naj Aziz

A series of laboratory experiments were conducted on a variety of bolt types to examine the load transfer capacities of different profiled bolts in short encapsulation push testing. A 75 mm section of 150 mm long bolt specimen was anchored in a 75 mm long stainless steel tube using full resin encapsulation. Six types of different profiled bolts and two non - profiled bolts were tested. Bolts with higher profile were in general found to have greater shearing resistance and higher stiffness than low profile bolts. Widely spaced profiles allowed greater displacement at peak shear strength, and bolts with no profiles produced very link load transfer capability. Rough surfaced plain bolts showed a significant load transfer capability in comparison to a factory supplied smooth surface bolt which supports the belief that rusted bolts have higher lnad transfer capability that un-rusted bolt surfaces.

Jan 1, 2003

By Qiong Wu, Li Guo, Qinghua Gu

BP neural network is a multilayer feedforward network trained by error back-propagation algorithm, which is one of the most widely used neural network models. However, BP neural network has exposed more and more shortcomings and deficiencies with the expansion of the application scope. In the prediction of ore quantity, BP neural network has the characteristics of slow convergence and easy to fall into local minimum point. In order to obtain the global optimal solution, and to improve the defects of BP neural network, this paper proposes combination optimization algorithm of genetic algorithm (GA) and BP neural network to improve the speed and accuracy of forecasting the main design flow chart and the analysis of the sort distinguish algorithm are offered, and then some problem in the design and debugging of the algorithm are discussed. On this basis, the GA-BP neural network model is constructed and applied to optimize the initial weights and threshold value of BP neural network. This model choices the floating point coding method to encode the connection weights and thresholds, and divides subjects into several populations. Through the introduction of selection, mutation, crossover, initial weight and other operators, making operational synergies between the various groups. This study selects 30 geological units, 8 quantitative variables (Pb, Zn, Cu, Mo, Si, Ni, Co, V) and 12 qualitative variables to carry out empirical analysis. Then the simulation of the algorithm is carried out in MATLAB and the parameters are analysed. By normalizing the input samples, 22 groups of observation data are used as the training data for prediction, and the latter 8 groups of observation data are used as the test data to be verified. The results show that when the ore quantity characteristics are not very significant, the model will produce prediction bias. But the improvement of the algorithm increases the efficiency of the function approach capacity of BP neural network and conquer the BP neural network system’s instability. It provides an auxiliary guide for ore prediction, which have higher reference value.

Jan 1, 2017

"There is considerable evidence that all mine dusts do not present the same health hazard. Rank of coal and composition, especially silica content of the mine dust, shape, and surface charge are risk factors that affect the incidence and severity of CWP. Current efforts of Center researchers involve characterization of:•,size/shape/composition•,surface and functional groups•,particle interactions.Work is underway to prepare and characterize respirable coal dust samples, and to develop and evaluate techniques and procedures for the characterization of respirable dust. A suite of standard samples including anthracite, medium volatile and high volatile bituminous coals, quartz, clay, and rock dust have been prepared and thoroughly characterized with respect to the distributions of particle size and compositions. A comparison of the morphology of the standard dust particles with similar particles collected in an underground coal mine is given in Figure 43. Samples of these characterized (Standard) dusts have been distributed among various research groups associated with the Center.The aerodynamic diameter of a particle is a particularly important characteristic since this parameter determines the point of deposition in the human respiratory tract. A 3-dimensional numerical model for theoretically determining the equivalent aerodynamic diameter of irregular shaped particles has been developed and used to analyze coal dust particles and a particle shadowing technique has been developed for .experimental 3-dimensional shape analysis (Figure 44). In the theoretical technique, the equivalent aerodynamic diameter of the particle is numerically determined from computation of the fluid drag on the particle. This allows the aerodynamic diameter of any regular or irregular shaped particle to be determined as a function of the particle's orientation or as an average over all particle orientations. The technique is quite accurate in that the aerodynamic diameter of several coal dust particles have been numerically determined to be within 5% of experimentally measured values."

Nov 1, 1988

By L. C. S. Dharmasiri, S. M. Shin, A. Senaputra, J. S. Sohn, K. H. Park, J. Avraamides

Reducing agents can be applied to leach metal values from natural and secondary resources such as laterite ores and deep sea manganese nodules and recycled materials such as spent batteries / catalysts which contain high-valent metal oxides of manganese, cobalt and iron. Selective leaching of some metals can be achieved by selecting conditions to control the saturated solubility and dissolution rates of metals from oxides or mixed metal/oxide matrices. The leaching results are rationalized on the basis of chemical species, Eh-pH diagrams and heterogeneous kinetic models. The role of reducing agents such as hydrogen peroxide, sulfur dioxide and iron(II) sulphate, in acid, alkali and in the presence of complexing ligands such as ammonia for the improvement of the leaching of metal oxides and metals is discussed. Previous studies on acid leaching of metals from nickel laterites, manganese nodules and spent catalysts/batteries in the absence or presence of reducing agents show that the rate controlling step involves the diffusion of protons through a thickening product layer on the particle being leached. It is shown that the leaching of nickel and cobalt from manganese nodules and zinc-carbon batteries in ammoniacal sulphur dioxide solutions also obey shrinking core kinetics.

Jan 1, 2014

By Aldino Campos, Frederico Carvalho Dias, Pedro Madureira, Patrícia Conceição, José Gomes-Pereira, Inês Tojeira, Andreia Afonso, António Calado, Luísa Pinto Ribeiro

Since 2008, the Portuguese Task Group for the Extension of the Continental Shelf has been operating the ROV "Luso" (rated for 6000m depth) for geological sampling of the deep North Atlantic seabed, performing surveys on, e.g., seamounts and hydrothermal vent fields. Amongst other sensors, the ROV is equipped with a full HD video camera with which still images of the deep ocean floor are recorded. Fixed on the ROV’s frame are two underwater "line" lasers, each generating a sharp green line (532nm) over the seabed. The two lasers are paralleled and calibrated at a set distance. Provided that the camera’s angle of view is known, numerical values for seabed surface area may be calculated using direct measurements taken from the pictures containing the laser lines. We present the corresponding main mathematical formulas, which are derived from simple geometrical considerations, and discuss how to generalize these results for an arbitrary camera tilt or pan. We present an example of application of our method by estimating values for percent coverage of rock substrate versus sediment. Our results are also relevant for determining seabed polymetallic nodule abundances from still images obtained during ROV surveys.

Sep 1, 2014

A field trial of the prompt neutron-gamma SIROLOG technique was undertaken by the CSIRO - Division of Geomechanics at Callide Coalfields during July 1989. The trial investigated whether the sonde could reliably be used for the determination of Ash and Iron Oxide (Fe2O3) in coal seams, which had a highly variable iron content. Ten boreholes were logged, being water filled of a nominal diameter of 120 mm. The logging probe employed a 1.6 ¦g 252Cf neutron source and a 51 x 51 mm BGO detector. The source to detector distance was 15 cm. The results from one exploration borehole at the Dunn Creek Mine are discussed in the paper. The rms deviations for ash and iron determination between the neutron-capture predictions of the geophysical logs and the laboratory - chemical assays were 1.9 per cent Ash and 0.88 per cent Fe respectively. Using existing empirical equations which relate iron oxide concentration in coal ash to Initial Deformation Temperature (reducing conditions) at Callide, it may be possible to indirectly determine ash fusion properties as least as accurately, on a more detailed ply-by-ply basis, and more cost competitively than current laboratory techniques allow.

Jan 1, 1991

Provide mine safety personnel, MSHA inspectors, and original-equipment manufacturers with guidelines and a check list for inspecting rollover protection structures (ROPS) being used in mining operations. The Problem ROPS are provided on mobile surface mining equipment to protect operators from such safety hazards as machine rollovers, falling objects, and collisions. However, the protective capability of a ROPS can be greatly reduced if it is damaged. Certain kinds of damage, such as hair- line cracks, corrosion, and loosened bolts, may occur as a result of normal machine use but may not be recognized as unsafe by untrained personnel. Therefore, the Bureau of Mmes designed a manual which can be used by mine personnel when inspecting ROPS equipment. The Manual The manual was prepared to help acquaint mine safety personnel and MSHA inspectors with typical ROPS deficiencies and their causes. It provides a systematic means for inspecting ROPS so that the identified deficiencies and their causes can be corrected. It is suggested that an inspection of the ROPS be conducted after every 1,000 h of equipment operation, or sooner if the structure has been subjected to any unusual loads which could cause damage, such as a rollover, highwall caving, or collision. The manual also details common deficiencies in the structure and attachment hardware which may affect the service life. The checklist, when used as instructed in the manual, provides a means for systematically inspecting the structure to ensure maximum protective capability and conformance with applicable Federal regulations.

Jan 1, 1986

By G K. Robinson

Variations in many aspects of physical and chemical grade are often of concern to mining operations and mineral processing plants. In most circumstances these amounts of variation are predictable. At the time of planning new operations, we should be able to predict the amount of sampling and testing variation which our sampling devices, laboratory procedures and on-stream analysis devices will achieve. We should know how well our stockpiles, reclaimers and bins will homogenise material (or whether segregation will actually increase the amount of variation). We should be able to predict the amounts of variation that will occur on the important time or tonnage scales at the crucial p oints in our proposed operation. And once these amounts of variation are reliably known, mine planning will seem a little bit more like dealing with known knowns rather than like dealing with unknown unknowns.The first step towards quantifying amounts of variation for planned operations is to assess amounts of variation for existing operations. How many operations have estimates of amounts of variation in their databases? How often are people able to partition amounts of variation into amounts due to sampling error, amounts due to sample preparation, amounts due to assaying, and the amount of real variation in the stream of material?CITATION:Robinson, G K, 2012. Making sure that the amount of grade variation is a known known, in Proceedings Project Evaluation 2012 , pp 159-162 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By Kwang-Hyun Jeon

Recently, 3D printing technology in the manufacturing field is in the spotlight. In the construction industry, similar rapid prototyping technology that does not use conventional form can be applied to meet the demand on free formed structure that can provide aesthetic value and functionality. Conventional formwork can increase construction cost and period for various structure with complex shapes while it has numerous advantages such as high strength, convenience, accuracy and good quality of surface roughness. To meet the demand on free formed structure, automated freeform construction systems such as Contour Crafting and Concrete Printing have been developed with active collaboration between university and industry in USA and England. However, details on the system have not been fully released in public, so the possibility of its fusion and spin-off technology cannot be expected. In this paper, cost-effective solution for mechanical and control system for constructing a free curved structure without mold are described. As an appropriate material for the system, fiber reinforced mortar was selected by experiments on compressive strength, setting time and fluidity. After performing G-code simulation, transfer and extrusion experiments with the selected mortar mix were performed and the possibility of the development of automated freeform construction system was demonstrated. Based on this research results, it is required to keep the automated freeform construction system improve and extend it into the new application area in construction industry.

Aug 1, 2013

By R. H. Grau, R. B. Krog

The National Institute for Occupational Safety and Health (NIOSH) has investigated the unique ventilation requirements of large-opening mines to help identify and evaluate the effectiveness of various fan types to improve the ventilation and air quality in the underground workplace. Large-opening mines, with their low airflow resistance factors, can be ventilated with free-standing auxiliary fans because airflow pat-terns in these mines are primarily controlled by airflow momentum. The flow characteristics of both vane-axial and propeller fans were investigated and tested at four large-opening mines to assess the effects of fan location on recirculation and entrainment. Each fan type has its own airflow, entrainment and penetrating air-flow characteristics, and operating costs that are advantageous for specific applications. Either fan type can be used for most auxiliary applications. However, this research has shown that the optimum placement and use criteria for propeller fans differ from those promulgated by the U.S. Bureau of Mines (USBM) for vane-axial fans Brechtel et al. (1985)