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Jan 1, 1942

The process of electrostatic separation was developed in the late 19th century, but did not make much headway for about 25 years. High dc voltages, of the order of 20 kilovolts, are involved, and the only means of obtaining such voltages at that time were by the use of frictional machines, such as the Wimshurst. These were not reliable, for two reasons:-a. If a spark discharge occurred it took an appreciable time before a steady voltage was again attained.b. In damp weather the machines were almost useless.In the first 20 years of the 20th century the advent of mechanical and vacuum-tube rectifiers led to promising developments of 'the process. In the early 1920's flotation became widely used commercially, and proved to be more reliable, and capable of wider application, than electrostatic separation. During the last 15 years or so, with a better knowledge of the fundamentals forming the basis of the process, electrostatic separation is beginning to compete with flotation, especially in the treatment of smallsizedgranular material, such as beach sands. Electrostatic separation can be, and is, widely used in many cases where flotation is impossible, such as in the cleaning of food products which must be kept dry.

Jan 1, 1950

In this paper we present the results of preliminary investigations into the applicability of new laboratory scale tests for the prediction of operating gap and specific throughput in high pressure grinding rolls (HPGR). The work is a part of the CAMIRO HPGR research program being conducted at the University of British Columbia, which aims to develop a suite of small-scale tests and procedures for the selection and sizing of HPGRs. A focus of the presented study is to test sample types in terms of their terra-mechanics based characteristics and relate them to specific throughput and gap results from pilot HPGR testing on the same samples.

Jan 1, 2012

By Ronaldo Esteves Ribeiro, Jefferson Felipe Faria Clemente, Carlos Victor Francisco dos Santos, José Herbert Dolabela da Silveira

n recent years, the market for thick plates has been highly competitive, in this scenario the plates quality is a critical success factor. In this process, the quality of the cut in thick plates is one of the important requirements for the customers, by the visual aspect as well as the technical aspect of the plate application. In the shear line, the cutting is done by shearing to trim tips, subdivide plates, trim side edges, remove samples, eliminate defects, etc. The cut is obtained by the penetration of the upper knife in the plate, causing plastic deformation in a certain region and hardening. If the clearance between the knives is adequate, the cracks will be close to the centre of the plate thickness and will result in a good cut quality. This work will present the theory of cutting of thick plates, the types of shearing, the quality of the edge in the cut, the types and the main characteristics of the knives.

Oct 1, 2019

By Marc Boyer

Modern civilization, modern industry, and modern standards of living, bring into, sharp relief the present-day essentiality of metals .and minerals, and the wide and diversified use which is made of them. Any attempt, therefore, to appraise the international situation today must take into consideration the metal and mineral resources of the world. If, as some believe, the world is divided into two distinct ideologies of political belief, one unalterably opposed to the other, so that armed conflict is unavoidable, then the question of national strength in mineral resources becomes of paramount importance. If, however, it is possible to avoid war by raising the standard of living in the underdeveloped ?areas of the world, thus ensuring all peoples everywhere against the dread spectres of starvation and disease, then the development of the world's mineral resources assumes even greater importance. Today it is difficult to realize that, prior to the industrial revolution in Great Britain, only a few of the metals and minerals now in common use entered into the everyday life of the people. !iron and steel, copper, lead, tin, and zinc, usually in .their unalloyed forms, along with the more common industrial minerals, were those most widely used, and then only in limited amount. With the advance of technology in metallurgy and in fabricating skills, the list of commercial metals and minerals has expanded until today they number more than eighty.

Jan 1, 1951

By F Ramos

Conventional techniques for resource estimation generally involve the laborious analysis of variograms and the specification of parameters for covariance functions. In large deposits, construction of resource models and their update require significant amount of manual work, expert knowledge and time. In this paper we take a machine learning view to the problem of resource estimation. This is a non-parametric Bayesian method, leading to automatic parameter estimation (learning). Through Bayesian learning, the parameters of the model can be obtained by optimising a quantity known as the marginal likelihood. The main advantage of this approach over conventional maximum likelihood estimators is that the objective function incorporates the OccamÆs razor principle. This allows the comparison of different statistical models û for example, models designed with different covariance functions û and naturally penalises complexity, thus avoiding overfitting. Our technique presents significant flexibility for the definition of mean and covariance functions and permits the usage of more sophisticated models.The second contribution of this work is the formulation of a data fusion mechanism that continuously updates the resource model. As mining progresses, more information becomes available. For example, the hardness of the rocks can be measured while drilling blast holes, grades of ore and contaminants are obtained from cone logging. This information is in general available at a finer spatial resolution but can be more uncertain. The data fusion mechanism can seamlessly estimate the uncertainties of the different types of information and fuse them as new measurements are acquired. This procedure can significantly improve the quality of the resource model, defining new grounds for stochastic mine planning. We demonstrate the effectiveness of our approach in estimating iron ore deposits by integrating information about different grades.

Sep 26, 2011

By K White, R Hardie, J Merritt, B Kirsch, R Lucas

Constructed stream diversions are a common element of mine sites across Australia. A review of constructed stream diversion performance in the Bowen Basin funded by the Australian Coal Association Research Program (ACARP) in 1999 found over 80 per cent of constructed stream diversions failed to meet regulator and operator expectations. Since that time, improvements have been made in the assessment, design, monitoring and management of constructed stream diversions. Fundamental to these improvements has been the development of a better understanding of the regional stream systems and efforts to replicate the natural stream processes in the function and operation of constructed stream diversions.This paper discusses the history of constructed stream diversions through the Bowen Basin in central Queensland recorded in the outcomes of a series of ACARP funded research projects. Further, the paper reports on the outcomes of a current ACARP funded project that has reviewed the success or otherwise of constructed stream diversions in the region. The assessment has compared the performance of diversions that have been designed to replicate and provide for ongoing stream geomorphic processes with those diversions that were designed and built prior to the development of these design improvements. Based on these investigations we have identified design and construction successes and issues requiring further research and management attention.CITATION:White, K, Lucas, R, Hardie, R, Merritt, J and Kirsch, B, 2013. Challenges and opportunities for constructed stream diversions in the Bowen Basin, Central Queensland, in Proceedings Water in Mining 2013 , pp 73-82 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By Ari Glazer

"Every year the tunneling business is expanding and collaboration with the International Society of City and Regional Planners (ISOCARP) for the future design of cities and urban communities is in the making. During the last half of this century, billions of people migrated to cities, and it is estimated that by 2030 almost five billion people worldwide will reside in urban communities. Hence, “Underground development will be an important tool in reshaping our urban areas to meet the challenges of the future without destroying their heritage or worsening their surface environment” (Esaki, 2005). In 2013, the Organization for Economic Co-operation and Development (OECD) estimated life expectancy to be around 80 years, meaning that in less than a decade we will need to bury billions of people in cities and urban communities, while trying to retain the deceased’s beliefs and customs. Religion plays a major role in our lives, and many people worldwide still decline to cremate their body after their death; therefore, cemeteries are essential for city inhabitants. Rites and traditions usually call for burials to be near the place of residence, which allows the remaining family members and friends to visit the grave frequently, at least in the first years. This is a challenge that urban designers and architects must confront while trying to solve the problems of future urbanization. In recent years, population growth, the rising cost of land and the extensive preservation of green areas have made cemeteries a burden and a nuisance, particularly for large cities and communities. Many graveyards that were once on the city's outskirts have become lifeless islands in populated areas (Fig. 1), rarely visited by the second and later generations. Cities worldwide face the challenge of allocating less land to maintain current burial practices. In response, some cities have begun to bury their dead at a great distance from the community; others have started to stacked burials, one on top of the other, while still others are constructing buildings and even skyscrapers for the practice of burial (Fig. 2)."

Jan 1, 2016

By C Mroczek, B Mitchell

Perilya Broken Hill, from its inception, has budgeted for more than 2.0 million tonnes per year from the Southern Operations. This tonnage was planned to come from in excess of 100 stopes per year in a remnant mining environment with numerous mined voids and consequent mining challenges. To mine an average of two stopes per week requires patience, flexibility and detailed knowledge to best manage the potential risks and hazards. The evolution of the Perilya Broken Hill Mine Planning Process has necessitated the establishment of a process to identify and manage these risks during the planning stage in a reliable but efficient manner. This process is to ensure that vital steps for each stope are not missed, and that each personÆs work can be tracked by other members of the team. This paper outlines the planning process from resource to stope closure.

Jan 1, 2005

By R. J. Wysor

Discussion of the paper of R. J. WYSOR, presented at the New York meeting, February, 1916, and printed in Bulletin No. 106, October, 1915, pp. 2161 to 2170. LEONARD WALDO, New York, N. Y.-Will Mr. Wysor kindly give us more information as to the pyrometers used and the temperature measurement? R. J. WYSOR, So. Bethlehem, Pa.-We used standard Bristol pyrometers with bare fire ends. These were standardized both before and after the tests with salt and pure aluminum. We also interchanged the pyrometers. J. W. RICHARDS, So. Bethlehem, Pa.-Did you attain any results which gave you approximately the value of the heat insulation at any of the furnaces? R. J. WYSOR.-In the first installation we were afraid to put in the insulation throughout the hot-blast main for the reasons mentioned in the paper, but we used the insulating brick in two 8-ft. sections in straight lengths of our hot-blast mains. Owing to the high conductivity of the steel shell, the temperatures which were taken on the outside were not representative of the two temperatures resulting from heat flow through the insulating brick. I believe that when a hot-blast main is insulated

Jan 5, 1916

By Gordon M. Pugh, David G. Rasmussen

INTRODUCTION Variations of cut-and-fill stoping are the most com¬monly used methods for mining narrow, nearly vertical veins in the United States. These methods offer the best results for maximum recovery with minimum dilution of ore from veins that are irregular along either the strike or dip. The vein is developed along the strike length in 61 to 122-m (200 to 400-ft) blocks or stopes and vertical lifts of 48 to 61 m (160 to 200 ft). The level development is either on the vein or parallel to the vein with crosscuts intersecting the vein at right angles. Chutes, manways, and haulageways are established in the center of the stopes at the lower level of the ore block. Mining then proceeds by blasting down horizon¬tal cuts of the vein in both directions from the chutes. As the blasting continues to the outer limits of the stope, the broken ore is slushed into chutes. When a complete horizontal cut has been made, the service raise, including chutes, is raised to a height of a few feet from the back and the stope is filled with either sand fill or waste rock. Then the mining cycle is re¬peated until the stope reaches the level above. LEVEL DEVELOPMENT PRACTICES FOROVERHAND CUT-AND-FILL STOPING The two basic methods used are: the development of the haulage drift within the vein, or development of the haulage drift paralleling the vein in the foot or hang¬ing wall with crosscuts intersecting the vein perpendicu¬larly at 61 to 122-m (200 to 400-ft) intervals. The il¬lustrated methods of development show some of the variations which can be used to develop a stope block. Development for cut-and-fill stoping does not require the more elaborate schemes outlined for shrinkage or sublevel long-hole stoping. Many factors must be considered before deciding on a particular development plan and usually the nature of the vein or host rock will dictate which specific method to use. If the vein is relatively straight, then develop¬ment on the vein is feasible. Excessive ground pressures will necessitate the leaving of a sill pillar (Fig. la) and highly fractured or "heavy" ground will require timber¬ing (Fig. 1b). Development on the vein has the advan¬tage of reducing capital outlay and waste handling prob¬lems since the mined rock has value. But removal of the sill pillar is costly and time-consuming. Also, where no sill pillar is left, excessive timbering and subsequent level repair is a drawback. Development in either the footwall or hanging wall is the more common procedure and offers greater flexi¬bility in overall development of consecutive stoping blocks by partially disassociating the level development from stoping (Fig. 2). Chutes, manways, and service compartments com¬prise the next stage of development and are established in a variety of ways. They provide access to the stope, ventilation ducts, and muck removal. Several different development systems are in common use and average costs for each have been developed. Raise borers are used to establish ventilation and ac¬cess from level to level. They are normally reamed with 1.5 or 1.8-m (5 or 6-ft) cutterhead and may either be left bald or lined with a 1.2-m (4-ft) diam corrugated liner plate, depending upon ground conditions. The use of an Alimak raise climber is another effec¬tive method of driving a raise from level to level. The size usually is 2 m (7 ft) square. This will accommodate square-set timber which is later installed. This method of raising is not common, although it is a valuable tech¬nique especially when level spacing is several hundred feet.

Jan 1, 1982

By V. Falmagne

The mining sequence at Noranda?s Bell-Allard mine calls for two mining fronts retreating toward a central pillar known as the Retreat Zone between pyramids A and C. It is clear from numerical modelling and rock mass characterization that the induced stress level in the pillar will exceed the rock mass capacity. A mining plan was developed including the re-dimensioning of stopes in the Retreat Zone, additional ground support and instrumentation in order to ensure the safety of the workforce and to maximize ore recovery while minimizing production delays. The mining strategy consists in allowing the rock mass to fracture and fail progressively while maintaining control of the existing openings with the appropriate support. A systematic analysis of rockbursting and caving hazards was conducted for all accesses and stopes in order to plan ground support and instrumentation needs.

Apr 1, 2004

By M. Gunter, M. Buzon

"Talc formed by hydrothermal alteration of preexisting carbonate rocks is known to be nearly monomineralic, and lacking in amphiboles. In southwest Montana, talc formed from hydrothermally altered dolomitic marbles, and is still actively mined. These talc deposits are typically in contact with quartzofeldspathic gneiss and marble. Accessory minerals vary between these rocks and the ore producing body; the identification and characterization of such minerals requires carefully selected analytical methods. Recent litigation and ensuing confusion over the petrology and asbestos content of these deposits challenges the talc mining industry in Montana, and elsewhere in the world. INTRODUCTION Commercial talc has been mined from the deposits in southwest Montana since the 1940s, and by 1956 the region had output 200,000 tons of talc ore (Chidester et al., 1964). Commercial talc refers to rocks containing more than 20% of the mineral talc (McCarthy et al., 2006); the ores from Montana typically contain upwards of 90% talc. This region remains the leading domestic source of talc in the U.S. partly due to the reserves in the area, and partly due to the diagnostic purity of the ore compared to that of other regions, some of which are no longer actively mined. The mineral talc, a sheet silicate, is expressed by the formula Mg3Si4O10(OH)2, and therefore can form in geologic environments that are rich in Mg, Si, O and water. The protolith for the talc deposits in southwest Montana is a dolomitic marble, but other common protoliths include ultramafic igneous, mafic igneous, and siliceous dolomites (McCarthy et al., 2006). Physical properties such as hardness of 1 on Mohs hardness scale, white streak and slippery feel are among some of the reasons why talc is so widely used as fillers in a number of industries. In decreasing order, ceramics, paper, paint, roofing, plastics, rubber, and cosmetics are the leading domestic industries that use talc despite the decreasing trend in U.S. talc use and production since 1994 (Virta, 2015). The purpose of this paper is to describe the mechanism of talc formation in southwest Montana by focusing on talc deposits and surrounding rocks in the Ruby, Greenhorn, and the Gravelly Ranges, and to relate the mechanism of formation to the composition of talc ores. The compositional data show mineral content of selected ores, and the major and trace element content of those minerals, specifically talc. Our electron microprobe (EPMA), powder x-ray diffraction (XRD) and x-ray fluorescence data for samples from five mines in these three ranges provide continued evidence of the purity of these ores despite claims made during recent litigation that these ores contain asbestos. The five mines that we discuss include the Beaverhead, Treasure, Regal, Willow Creek, and Yellowstone Mines (Figure 1.)"

Jan 1, 2016

By G. Hausen, H. Micka

"Modern signal and power electronics made adjustable-speed AC drives technically feasible and reliable and economically attractive. Cycloconverters are discussed as a proven technology for mine hoists. \IntroductionUntil rather recent technical and commercial advances in power and signal electronics, DC motors were used almost exclusively for applications requiring continuously adjustable operating speeds and torques. More recently, the significantly higher efficiency and the accordingly lower operating costs of AC motors gained importance. An effective and efficient speed control of AC motors requires the control of AC voltage and frequency. Table 1 shows typical applications of adjustable-speed AC drives.CycloconvertersOf particular interest to the mining industry are cycloconverters for hoist drives. The cycloconverter represents by far the simplest, most efficient and most economical means of converting a constant-voltage, constant-frequency supply into an adjustable-voltage, adjustable-frequency supply as required for the speed control of AC drives operating in the frequency range to half of the utility frequency.Cycloconverters feeding synchronous motors or induction motors are ideally suited for slow-speed direct-coupled drives."

Jan 1, 1988

By G. J. Grott

Direct Production Costs for Solar Sa 1t approximate the trucking cost for 160 Km. Operations near markets appear unusually attractive at first look. However, many desert operations have been plagued by dust storms yielding salt too high in insolubles for most uses. This paper relates the history of a successful operation in a dust storm area. Saturated brine from the solution mining of LPG storage caverns is evaporated in solar ponds yielding 99.95% sodium chloride (dry basis). Purchased energy is one-eighth that of vacuum pan operations. Production scale tests have proved it works at another desert location using a more complex brine. A new approach for refining soluble salts at ambient temperatures is demonstrated by bench scale and pilot work. Again, savings in purchased energy exceed 80%, even when temperatures are raised to reduce refining time.

Jan 1, 1988

By Tatyana A. Ivanova, Tamara N. Matveyeva, Anatoliy A. Fedorov, Tatyana V. Nedosekina, Valentin A. Chanturiya

An ingenious methodology purposively developed by the authors for comprehensive assessment of flotation properties, electrophysical characteristics and. crystal chemistry features of natural gold-bearing sulfide minerals of different origin has been used in this study. Examination of the elemental composition of the minerals, ion-molecular components of the liquid phase in suspensions, surface properties of sulfides and different flotation reagents sorption forms was performed using the methods of X-ray phase and spectral analysis, potentiometry, UV and IR spectrometry, computer image analysis, and computer simulation techniques. The role of isomorphous impurities in the formation of hydrophobic sulfhydric collector layers on mineral surfaces in complex ore processing has been elucidated. The parameters characterizing the variability of the Fe:S ratio in pyrite of different origin have been determined based on non-stoichiometry characteristics of natural gold-bearing sulfide crystals. An ingenious method of formatting and linear approximation of experimental data was used to find out the quantitative relationships between the impurity content, electrophysical characteristics, non-stoichiometry and floatability of pyrite from a number of different deposits. The effect of the impurity species present in sulfides on the characteristic pH value marking the floatability peaks as such and their trend of shift towards higher alkalinity has been revealed. A theoretical substantiation has been given to prognostic assessment criteria for processing characteristics of gold-bearing sulfide minerals with varying composition. New flotation reagents and advanced reagent systems which help to increase the contrast of processing characteristics for different gold-bearing sulfides, resulting in improved selectivity, have been developed. The mechanism of selective flotation of precious metal-bearing Fe and As sulfides achieved by using short-chain dithiocarbamates and a mixture of cyclic trithiocarbonate with oxyalkylsulfides has been analyzed.

Jan 1, 2003

By G. E. Anderson

The Asientos-Tepezala district is in the north of the State of Aguasca-lientes, about 30 miles north of the city of Aguascalientes, the capital. The district is reached by a standard-gage railway on the west side through the junction, Rincon de Romos, which is on the main line of the National Railways of Mexico from El Paso to Aguscalientes. The terminal is Tepezala. On the east side a narrow gage connects Asientos with the junction, San Gil, on the main line, Asientos to San Luis Potosi. Tepezala on the west side of the Asientos hills is about 2 miles from Asientos on the east side. The area between the two mining centers is separated by a low subdued divide which forms the central part of the hills. The district is in a group of isolated hills surrounded by characteristic bolsón plains. The hills rise above the surrounding plains about 6500 to 10,000 ft.; the highest peak is Alta Mira. The two mining districts lie somewhat upon the flanks of the hills at about the same elevation, 7200 ft. The district is an old one and has been known since early in the 17th Century when the mines were worked by the Franciscan Monks. Their mining operations, which were limited to the oxidized ore above the water level, consisted chiefly in extracting silver from the Santa Francisca vein. To judge from the old workings and the remains of surface plant, the operations were on a large scale. By modern mining operations since about 1900, the various mines of the district have been one of the principal sourees of ore for the smelter located at Aguascalientes. Topography The topographic features of the Asientos hills are largely controlled by the character of the underlying rocks. During the Tertiary period, the entire group of hills was probably covered by extrusive volcanic material in the form of cones and lava flows. The central part of these have since been carried away by erosion, so that remnants have been left along the borders of the hills. These remnants form rather conspicuous peaks,

Jan 1, 1927

By A. J. Barry

A method was developed for testing the anchorages obtained with 3/4-inch, expansion-type, headed bolt and shell assemblies. The apparatus is a modification of that used in testing -inch-diameter, slotted-type bolts. Four makes of expansion-type shells were used in 64 tests made in sandstone and shale roof. The results show that for 3 makes of shells the anchorage effectiveness is independent of the installed land, and for the fourth make of shell a better anchorage is obtained when instilled at a load of 8,000 pounds. The results also show that deformation of the expansion plug influences the majority of the anchorages obtained with two makes of shells. This deformation causes a larger increase in displacement for a given added increment of load. The data from 48 of the 64 tests were combined to establish a relationship between average displacement and increase in bolt load (above the installed load). This relationship can be used to evaluate the anchorage effectiveness of any 3/4-inch-diameter, expansion-type, headed bolt and shell assembly tested in the field.

Jan 1, 1956

By B. Hayen

The principal advantages of fibre optics as compared to copper wire are well known and include almost perfect electromagnetic isolation, light weight, small size, excellent transmission security and substantially better bandwidth/distance performance. The decreasing cost of the optical fibre technology (both fibre cable and equipment) has led to another generation of private networks, which provide much larger bandwidths, very high reliability and an increase of the maximum geographical coverage. The larger bandwidth allows to transport all types of information on a single network. Typical communication requirements are speech (audio), computer data, LAN info, control information, video, etc. OTN or ‘Open Transport Network’ is a transmission system based on the latest available technology in fibre optics. It is characterized by the dual ring approach, resulting in high network availability, and the integration of different types of services in one network. As such, it can fulfil almost all transmission requirements for voice, data, LAN, video and any special service required.

Sep 1, 2001

The primary (sulphide) resources at Aphrodite are refractory in nature, requiring an oxidation process stage to be introduced to facilitate extraction of the gold. The company is investigating the use of pressure oxidation (POX) as the oxidation method for processing of high grade gold bearing concentrate it plans to produce at Aphrodite. POX has been used extensively around the world for the past 30 years and continues to be the favoured option for a number of refractory gold plants currently in the design and construction stages. Initial pressure oxidisation testing investigated the effect of temperature, pressure and grind size on a bulk flotation concentrate prepared from Alpha lode material. The concentrate averaged 47.3 g/t gold and was prepared from a composite of core samples averaging 1.49 g/t gold. Sub-samples of the concentrate were subjected to POX for 1 hour resulting in rapid oxidation during this very short period. Testing undertaken showed that there was a significant increase in sulphide oxidisation at higher temperature (220°C) and pressure (2,500 k/Pa) for the two grind sizes (75 and 20 microns) evaluated. The proposed flowsheet, OPEX and CAPEX are critical aspects for project development.

Jan 1, 2014