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By M. Le Roux

Fine coal (-500 µm) is notoriously difficult to dewater. It is not uncommon for a dewatered product to have a moisture content as high as 30 per cent after vacuum filtration. This poses several handling and financial problems to such an extent that a lot of fine coal is discarded onto slurry waste ponds. A novel way of dewatering fine coal was developed at North-West University. It entails deliberately damaging the filter cake during dewatering to allow for an increased flow of air through the cake at the expense of the applied pressure differential. This method resulted in an average improvement in final cake moisture of between 3 per cent and 5 percent when executed in the laboratory under controlled conditions. A device was designed that could be fitted onto existing belt filters that would damage the filter cake as it passes by. This device was tested on a vacuum belt filter installation at a coal beneficiation operation in the Waterberg coal field in South Africa. The results showed a 3 per cent reduction in final moisture of the cake, proving the validity of the method at full industrial scale.

Jan 1, 2012

Effect of Iron on ash fusion temperature and waterwall deposits FeS, H2S on tube material corrosion and erosion [ ]

Jan 1, 2005

By Charles E. Wait

IT is said by some that the occurrence of a deposit of sulphide of antimony in Southwestern Arkansas has been known for fifteen or twenty years. Whether or not such is the case I am not prepared to say, but I am not able to find any record of such a discovery, or any analysis of antimony ore obtained from that section, published at so early a period. The present discoveries, that seem to be attracting some attention, date back to the winter of 1873-74. At that time a vein of ore was found by Mr. Robert Wolf, in honor of whom the vein was named, and still is called, "the Wolf lode." At the time of the discovery the ore was unknown to the prospector, and its composition was not thoroughly understood in that locality until samples were sent to several analytical chemists, who pronounced it sulphide of antimony-stibnite. Since the discovery of this ore there have been three mines opened, and a number of interesting minerals of the antimonial series have been found. I have had an unusually good opportunity to collect specimens from these mines; and it is owing to the constant inquiry concerning the character of these ores that I have collected for publication the results of quite a number of analyses, sufficient I trust to clearly point out their composition. This is one of the few localities in the United States where antimony ore is found in workable quantities; I say workable quantities, because two different shipments of ore have been made to English reduction works, and in both cases excellent returns were made. The discovery of these deposits will, it is hoped, give rise to a prosperous and remunerative industry at no distant day, and when fully developed they may yield ore in sufficient quantity to supply the regulus for the home demand, thus adding wealth not only to those interested, but also to the State of Arkansas. The three mines are situated in the northern part of Sevier County, and may be reached by the St. Louis, Iron Mountain and Southern Railway to Fulton, thence by wagon-road to Columbus, Nashville, Centre Point, and to the mines. During most seasons of the year the

Jan 1, 1880

By W E. Vance, B H. Ashton

The emission of seam gases into underground workings in coal mines is acknowledged as a major hazard, particularly methane due to its possible ignition. Acknowledge of seam gas parameters is important for the prediction of gas emission rates into the ventilating air current. They are also important as the basis for the evaluation of the likely contained gas as a possible energy source.   Gas content determinations for the Kupakupa seam have been made at the Huntly West Mine.  Applying the method of Creedy (1986) to face samples, gas contents of 1.80 and 1.66 have been determined. Using desorbed and residual gas content data a content of 1.92 m3/t has been derived. These are on an ash included basis. Calculations using the adsorption equation of Kim (1977) and coal quality have given a gas content of 2.19 m3 t. Long-hole exploration drilling at Huntly West Mine has provided information on gas pressure. A pressure rise test has given a reading of 500 kPa (absolute); this is low compared with the pressure given for the determined gas content from theoretical adsorption isotherms.

Jan 1, 1991

By Sudhir Kumar Kashyap

In underground activities ground control is a challenging problem. It affects safety, production, and efficiency. As per statistics of accident data, ?fall of roof/sides? is one of the major causes of mine accidents. In many cases, our experiences and understanding of soil and rock behavior still fall short of being able to predict how the ground will behave. Presently, empirical approaches to design are widely used in estimating mine support parameters. Under these circumstances, expert judgment plays an important role, and such accidents can be obviated with accurate measurement and optimization of data and analysis using the neuro-fuzzy technique of artificial intelligence. Recently, a neuro-fuzzy hybrid approach has become one of the major areas of interest in engineering fields because it gets the benefits of neural networks as well as those of fuzzy logic systems, and it removes the individual disadvantages by combining them on the common features. Neural network and fuzzy logic technologies have common features, such as a distributed representation of knowledge, the ability to handle data with uncertainty and imprecision, etc., like in ground control. Fuzzy logic technique has tolerance for imprecision of data, while neural networks have tolerance for noisy data. In this paper we have focused an intelligent technique, i.e., neuro-fuzzy technique, to approximate the setting load given to the standing support (props) erected for the purpose of supporting freshly exposed roof during underground mining. We have used twelve input variables of rock parameters, and after having trained using a neural network with a sigmoidal function as an activation function, simulation was done to find the output parameter, i.e., the pre-load (setting load)to be applied on props. Outputs of the neural network were again fed to the fuzzy system together with the twelve parameters, incorporating five triangular membership functions for each parameter. Final optimum output was approximated using the MATLAB program, which was found to be satisfactory. Neuro-fuzzy technique has better performance over individual neural networks or fuzzy logic technique.

Jan 1, 2012

By C. Sun

The Leeville underground mine has been in operation since 2006 and currently produces 3,500 tons of ore per day with an average gold grade of 0.34 opt. The mine has a large horizontal extent of 2,500 feet by 500 feet and a vertical extent of 20 to 200 feet. Based on the characteristics of the ore bodies, a long-hole stope and cut-and-fill mining methods are used at the deposits which are divided into several mining zones. Cemented rock fill (CRF) is used as the backfill in the open stope. CRF design includes the aggregate design, the ratio of cement and fly ash design, and strengths for the long-hole stope and cut-and-fill. In the aggregate design, the particle size distribution is one of the most influential aggregate characteristics in determining how it will perform as a basic backfill material. Gradation helps determine durability, porosity, cement and water requirements, strength, and shrinkage. To cut the backfill cost, fly ash usually is added into the binder to replace some part of cement. However, adding fly ash can affect the strength of the backfill. The reasonable percentage of fly ash is also important for making a good and low cost backfill. Based on the different mining method, the different backfill with different strength is designed. A systematic quality control procedure for aggregate and backfill is followed. After four yeas application, CRF system in Leeville achieved very good results.

Jan 1, 2011

By Roberto Maldonado

El presente texto señala el proyecto de profundización en la mina Animón considerando sus características como: geología e hidrogeología, parámetros geomecánicos, niveles de producción, costos de capital y operación, eficiencia del sistema, flexibilidad para cambios en las operaciones, reservas de mineral y consistencia con el sistema de explotación. De forma que a través del conocimiento de estas y de las herramientas gráficas tridimensionales, se pueda analizar las diferentes alternativas, incluyendo condiciones que debe cumplir el proyecto de profundización, el cual abarca también los servicios auxiliares y ventilación.

Sep 12, 2005

By Maya Kamenetsky, Khoi Nguyen, Natalee Bonnici, Steve Walters, Claire McMahon, Julie Hunt, Ron Berry

"The analysis of meso- and micro-scale textural attributes has been undertaken on ore samples from the Ernest Henry iron oxide-copper-gold (IOCG) deposit in NW QLD. Quantified textural data including grain size, shape and mineral association have been extracted from classified images of core with the aim to better predict potential mineral processing behaviours such as comminution, liberation and flotation. Data have been extracted from images of intact core at meso- and micro-scales using high resolution continuous images collected using automated core-logger technology, SEM-based and optical microscopy platforms.The results of this study will show examples of quantified size, shape and mineral association data from meso- and micro-scale classified images. Analysis of the data shows that there are domains of variable grain size and mineral association that can potentially be related to crushing and liberation behaviour. The trends that are observed at the drill-core (meso-) scale are consistent with those at the micro-scale. The results from the micro-scale analysis show that the domains defined at the core-scale have clearly different chalcopyrite sizes and shapes as well as variable bulk mineralogy.INTRODUCTIONInnovations in technology have allowed automated extraction of information about mineral shape, grain size and mineral association, i.e., texture, from meso- and micro-scale images of intact rocks. The overall aim of this research is to investigate trends in quantified textural data that can potentially give an early view of processing parameters such as predicted grind size and liberation behaviour."

Jan 1, 2009

By Tapio Leskinen

"l. IntroductionA reliable sampling system is the basis for an on-stream analyzer. This was realized in Outokumpu company when the development work of the Courier 300 On-Stream X-ray analysis system was started. Because Outokumpu Oy is a mining and mineral processing company, its engineers have been able to thoroughly test sampler prototypes in actual operating situations. The sampler development has been going for several years in close co-operation between company's concentrators, the Institute of Physics and the Instrument Division of Outokumpu Oy. The most active part of the work was done between 1969- 1972. Besides the reliable operation of a sampler special attention was paid to the representatively of the samples taken by the samplers. 2. The Courier 300 Sampling SystemThe sampling system comprises up to fourteen sampling circuits in one Courier analysis system. Each circuit consists of the following components:1. Primary sampler 2. Secondary sampler 3. Cleaner screen 4. Feeding tank5. Sample cell6. Timer-controlled sampler7. Pumps, sumps and pipesSecondary samplers, cleaner screen and feeding tanks are included in the secondary sct1npling system. The sample cells are located in the spectrometer cabinet of the analyzer."

Jan 1, 1976

By D. J. Hallbom

This paper presents a novel methodology for the hydraulic design of mine backfill distribution systems. The ?operating range? method uses the concepts of the hydraulic grade line and equivalent pipe length to determine flows and pressures as the pipeline route and static head change over the life of the mine. The operating range method is easy to learn because it is semi-graphical and uses well-known design concepts (e.g., the hydraulic grade line) and slurry design models (e.g., the Durand deposition velocity model). However, by changing the paradigm in which these concepts are used, the operating method allows all potential pipeline cases to be analysed simultaneously without the need to know the exact pipe routing. It also allows the hydraulics engineer to quickly identify ?pinch points? and ?slack flow? zones, to estimate the effect of changing the size or length of any given section of pipe, to assess the impact of changing the material properties of the backfill slurry, to size the slurry pumps, and to size and locate rupture discs when required.

May 1, 2007

By S D. C Rabone

An elongate belt containing granodiorite stocks with associated stockwork molybdenum mineralisation in west Nelson is correlated with the I-type Separation Point Suite of mid Cretaceous age. Trace element characteristics of the 'Mo-granites', and the Separation Point Batholith strongly suggest a primitive, subcrustal origin for these granitoids, by partial melting of oceanic basaltic crust or upper mantle material in a subduction zone. They were emplaced in the upper crust without undergoing significant differentiation or contamination by sialic crust. Molybdenum, which is at levels of approximately 5 ppm in unaltered granite, is not significantly reduced in altered (but unmineralised) granite. This suggests the metallisation has a magmatic, subcrustal source and is not derived by hydrothermal leaching of upper crustal rocks or the granitic host rocks. Geochemistry of the 'Mo-granite' belt, in particular low K2O, calc-alkali to calcic Peacock Index, high Sr and TiO2, and low Rb, Nb and F, suggest classification as calcic granitoids similar to those which host porphyry copper deposits, indicating grades of mineralisation are likely to be low.

Jan 1, 1987

By Paul J. Ehret

With the passage of the Surface Mining Control and Reclamation Act (SMCRA), and the implementation of state permanent programs, underground coal mining operations are for the first time subject to government regulations regarding subsidence. These regulations now and in the future will directly affect the manner in which mining companies mine their coal. Since the promulgation of the original final regulations by OSM, numerous changes in those regulations have been made and many additional changes are pending in the near future. This paper will discuss state and federal approaches to regulating underground coal mines and examine issues surrounding future subsidence regulations.

Jan 1, 1986

By P. N. Anyalebechi

The effects of solidification rate on the cast microstructures of aluminum alloys 6009 and 6016 have been investigated with directionally cooled laboratory-size ingots, at 0.2-10.1 K/s and 0.4- 23.1 K/s, respectively. These ranges of solidification rate are within those observed in commercial-size ingots. In both alloys, the average dendrite cell size and second phase particle size decreased with increase in average solidification rate and with a decrease in average local solidification time. However, at comparable solidification rates, the dendrite cells and second phase particles are finer in the shorter freezing range alloy 6009 than in the longer freezing range alloy 6016. This is provisionally attributed to the earlier formation of second phase intermetallics at higher temperatures during solidification and to the formation of greater amount of the relatively coarse plate-like ß -phase (Al9Fe2Si4) phases in alloy 6016. In general, in both alloys, the types and relative amounts of the second phase particles in both alloys are independent of solidification rate.

Jan 1, 2006

By Zhang Chuanfu

Keywords: modified coprecipitation method, Ni-Co alloy powders, solid-solution oxalate, growth mechanism Homogeneous solid-solution oxalates of Ni2+ and Co2+ ions were synthesized by modified coprecipitation method and the composition and morphology of the fibrous solid-solution oxalates precursor were characterized by XRD, IR, DTA/TG and SEM analysis. The effects of feeding methods, pH values, precipitation temperature, reactant concentration, addition surfactant, alcohol washing and drying process on the morphology and dispersion of the precursor were investigated in detail. The experimental results showed that the coprecipitated powders have characteristics that are different from those of the mechanical mixtures with the same stoichiometry. Based on the observations of precursors growth and SEM morphology of the precursor, the oriented attachment was proposed for the well-aligned growth of the fibrous Ni-Co alloy precursor particles.

Jan 1, 2005

By J. I. Muñoz González

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

May 1, 2008

By Jan E. Nesset, James A. Finch, Wei Zhang

"Bubbles are unquestionably the heart of the flotation process. Their size and combined surface area are largely what drive the recovery process. This suggests that plant engineers should be aware of where their plants are operating with respect to what is achievable for these key parameters. The paper presents a model of how the key operating variables of frother type and concentration, gas rate, altitude (above sea level) and viscosity affect the Sauter mean bubble size (D32) and bubble surface area flux (Sb). The results are compared to a set of plant measurements that demonstrate the benchmarking capability of the approach. A case study is used to link hydrodynamic change to improved metallurgical performance.INTRODUCTION At the beginning of the 20th Century the early practitioners of flotation were aware of the importance of understanding bubble behaviour (Rickard, 1916) but measurement of individual bubble and gas behaviour in the industrial environment was not possible due to a lack of adequate sensors. This situation was not rectified until three quarters of a century later with the advent of industrially-robust sensors developed, notably, at the University of Queensland’s Julius Kruttschnitt Mineral Research Centre (JKMRC) (Schwarz & Alexander, 2006) and McGill University (Gomez & Finch, 2002). What emerged was not the chaotic environment perhaps expected, but defined relationships between gas rate, gas holdup, bubble size and the total surface area of bubbles. These relationships could be defined by mathematical expressions and predicted from an understanding of the key process variables (Gorain, Franzidis & Manlapig, 1997; 1999) (Hernandez-Aguilar, Gomez & Finch, 2002) (Gomez, Cortes-Lopez & Finch, 2003) (Nesset, Gomez & Finch, 2007). The early JKMRC work focused on a large pilot cell (3 m3) installed in plant environments, while the McGill work was initiated on flotation columns (Finch & Dobby, 1990) (Xu, Finch & Uribe-Sales, 1991) and later adapted to industrial mechanical cells (Cooper, Scott, Dahlke, Finch & Gomez, 2004) (Dahlke, Gomez & Finch, 2005) (Nesset, Gomez, Finch, Hernandez-Aguilar & Difeo, 2005). Yianatos of Santa Maria University (Chile), a graduate of the McGill research team, carried the work to industrial settings in South and Central America (Yianatos, Bergh, Condori & Aguilera, 2001). The methods of gas dispersion measurement are now well accepted and most major research centres and flotation cell manufacturers have adopted the technology (Pyecha, Sim, Lacouture, Hope & Stradling, 2006) (Yañez et al., 2009) (Collins, Schwarz & Alexander, 2009)."

Jan 1, 2012

By B. Kahraman

About 70% of the world?s total boron reserves are located in Turkey. Boron minerals are typically concentrated by attrition scrubbing followed by screening and classification to remove clay minerals and other impurities. These wet concentration methods, however, result in a considerable amount of accumulated tailings in large tailings dams. The tailings are approximately 28% solids and contain 14% B2O3. Problems caused by these tailings can be minimized by employing dry beneficiation techniques involving heat treatment. This method has been successfully tested on laboratory and pilot scales. During heat treatment, borax undergoes expansion in volume. The amount of expansion is dependent on the particle size, temperature and duration of heat treatment. Because the optimum temperature and the duration of the heat treatment are not well defined, the boron ore acts as a calcined clay mineral and is discarded along with the gangue. It is important to predict such parameters using mathematical formulations. Thus, a mathematical model is used to predict the required temperature and duration period prior to heat treatment. In the experimental study presented here, a series of systematic thermal tests was carried out in a muffle furnace. Two variables, temperature and time, were studied in a response surface design. A quadratic regression model was chosen and regression coefficients were calculated. Using a regression equation, the volume expansion of the particles in various circumstances can be predicted. The mathematical test results are then correlated with the experimental results to relate the optimum expansion of borax with heating time and temperature and with borax grades and recoveries.

Jan 1, 2008

By A. D. Davis, J. L. Sorensen, C. J. Webb

Environmental impacts from acidic mine drainage are growing national concerns that are particularly acute in the headwaters of the Rocky Mountain region. In the Black Hills of South Dakota, approximately one thousand mines are inactive or abandoned, most of them in the headwaters of major drainages. This paper examines the Bear Butte Creek basin, a heavily mineralized watershed with significant historical mining impacts and a surface gold mine permitted in 1997. The watershed loses its surface discharge to swallow holes in the karstic Madison Limestone. The integrity of the aquatic ecosystem was monitored with a suite of sitespecific bio-indicators. Stream surveys covered the entire reach of Bear Butte Creek from near its headwaters to the swallow holes in the Madison aquifer. Data from the stream surveys, water-quality sampling, and bio-indicator surveys clearly showed that water-quality impacts are limited mainly to Strawberry Creek and to the area of Bear Butte Creek near and downstream of the town of Galena.

Jan 1, 1999

The purpose of this paper is to describe briefly the clean-up procedure adopted at the treatment plant of Paringa Mining & Exploration Co. Ltd. at Kalgoorlie, Western Australia.A clean-up is carried out at the end of each four-weekly period, and all figures subsequently quoted are taken from a summary of the results of the eight periods ending 8th April, 1941.STRAKING AND AMALGAMATIONOf the total gold won 22· 77 per cent. is recovered by straking and amalgamation.The discharges of both the primary and secondary ball mills are pumped over a common set of five ten feet long by three feet wide straking tables, set at an angle of 10 degrees, before passing to the 14 ft. diameter by 30 ft. by 8 ft. Dorr bowl classifier.This classifier is in closed circuit with both of the ball mills, hence the whole of the circulating load of the fine grinding circuit, which approximates to 800 per cent., is required to pass over the straking tables. For convenience in handling, corduroy cloths are used in lengths of 5 feet, and are picked up and replaced by clean cloths at four-hourly intervals. The avaHable straking area provided is, therefore, 900 square feet, or approximately 3·30 square feet per original ton per 24 hours. The density of the pulp passing over the tables is about 54 per cent. solids, the area provided per ton of pulp per 24 hours being approximately o· 2() square feet. Washing of the corduroy cloths is carried out on the day shift only, about 800 lb. of strake concentrate being obtained daily.This concentrate is sluiced from the washing trough on the elevated straking floor to the 4 ft. by 2 ft. diameter amalgamating barrel located in the gold room below.The barrel is of standard design and is rotated at 25 r.p.m. It is charged each day at 4 p.m., and grinding of the strake concentrate at approximately 70 per cent. solids is continued until 8 a.m. the following day. The barrel is then stopped, and the contents generously diluted with water, and after a few minutes rotation some of the slime is carefully poured off through the small discharge hole. This dilution and decantation is repeated until a good deal of the valueless slime has been removed.A further quantity of strake concentrate is then charged to the barrel, which is allowed a further 16 hours grinding period. After again diluting and decanting, approximately 25 lb. of mercury and 15 lb. of lime are added to the charge, which is then given an amalgamation period of 2 hours before cleaning up.By the process of grinding, diluting and removal of slime by decanting...

Jan 1, 1941

By K Firmin

The Mt Tom Price orebody of Hamersley Iron Pty Limited consists of a folded hematite - shale sequence capped by a layer of goethite. Consequently, variations in iron content occur within the ore body, and as the overall grade is below that required to make specification products, selective mining must be carried out. A necessary preliminary to quality control of products based on selective mining is the production of advance data on the tonnages and grades of material to be expected in future mining areas. Bench plans showing zones of different grades and types of material anticipated are prepared from structural geological information. The grades of materials on a bench are essentially governed by the positions and attitudes of the shale bands. Quality control is exercised by blending different grades and types of material in primary crusher feed. Iron grade is the prime grade consideration although sometimes the level of phosphorus content must be considered. Pre-production grades are determined from assay of samples taken from blast hole cuttings. As shales are more friable than hematite, product fines are always lower in iron grade than the lump product. The realisation of contract specification grade is more difficult with fines than with lump, so maintaining the correct fines grade becomes a prime factor in quality control. Control of fines grade is presently effected by aiming for an appropriate feed grade to the primary stockpile. Studies to estimate fines grade directly by qualitatively taking into account material types are in progress. Quality control measures are checked by monitoring the crushing and screening plant output, and taking appropriate compensatory actions in the mine when required. Minor fluctuations in quality of fines can be blended out on stockpiles. The quality control measures described ensure constant quality products, and a good recovery of high grade material from the deposit.

Jan 1, 1971