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The acoustic signals emitted from a laboratory-scale ball mill were used for the estimation of the comminution of two complex sulphide ores, viz. Merensky and UG2 ores from the Bushveld Igneous Complex in South Africa. The digital acoustic signals were transformed to power spectral densities that could be related to particle size distributions (-75 µm to 4000 µm) in the mill by use of continuum regression. This approach is more general than principal component regression methods or Kalman filtering used previously and resulted in significantly more accurate calibration in the case of the Merensky ore, where approximately 93.4% of the variance in the particle size distributions could be explained. With fewer data available, the variance in the particle size distributions in the UG2ore could be explained less accurately (82.4%), but still satisfactorily. In addition, smaller particle sizes (less than 300 µm) could be modelled more accurately in the case of the UG2 ore.

Jan 1, 2000

By Gerrit V. R. Goodman

In This Chapter [Design and operation of machine-mounted scrubbers Dust control with scrubbers and blowing ventilation Dust control with scrubbers and exhaust ventilation Dust control with exhaust ventilation and no scrubber Dust control methods common to all continuous miner sections Dust control for roof bolters] This chapter explains how to control dust at continuous miner sections in coal mines where the main dust sources are continuous miners and roof bolters. In relation to dust, there are three categories of continuous miner faces depending on the type of ventilation and whether or not a machine-mounted dust scrubber is used. These are— 1. Mining machines with dust scrubbers used with blowing face ventilation 2. Mining machines with dust scrubbers used with exhaust face ventilation 3. Mining machines without scrubbers used with exhaust face ventilation The approach to dust control is somewhat different in all three of these. However, there are many dust control features (such as the need to provide adequate airflow) common to all continuous miner sections. For workers at roof bolter faces, there are two dust sources: 1. Dust from the continuous miner when it is upwind. 2. A malfunctioning dust collector on the bolter, which allows dust to escape DESIGN AND OPERATION OF MACHINE-MOUNTED SCRUBBERS [Almost all new continuous miners are equipped with scrubbers. When the dust is excessive, it is possible that the scrubber needs some maintenance.]

Jan 6, 2003

By H. E. Bartlett

In the operation of some flotation plants treating platinum ores it was found that there were imbalances between the inputs and outputs. The inputs and outputs were sampled as slurries and it was determined that the imbalances arose from biases in the sampling, despite the samplers having been designed according to well-established rules. The launders feeding the sample cutters, and the sample cutters themselves were redesigned using finite element analysis to model the flows. A new set of design rules were formulated. The application of a Components of Variance Analysis, to determine the variance of primary and secondary sampling and of analysis in the lab for a concentrate is presented to illustrate the need for frequent sampling of process streams.

Jan 1, 2002

By Q. H. Bui

The elastoplastic self-consistent model is one of the effective models to study the initial microstructure effect on the mechanical behavior of bulk materials. However, the use of this micromechanics-based model which takes into account only the Hall-Petch relationship at grain level for predicting the grain sized effects on the strength of the deformed materials is not accurate yet because of the fact that the dislocation density contributes also to the strengthening of this kind of materials. In this study, a modification made to the Hill-Hutchinson elastoplastic self-consistent model was proposed for investigating the microstructure dependence of the mechanical behavior of cold-drawn 6063 aluminium tubes. Because of the novel modification, an estimation procedure with two steps was required to identify the parameters of this micromechanical model. An acceptable agreement between experimental and theoretical stress-strain curves was achieved.

Jan 1, 2011

Three methods of gold analysis are briefly described highlighting some of the problems and advantages of each. The variation of results between samples and splits and due to method of preparation is illustrated. The mean per cent difference of the fire assay values from the means of sample split values for three cases is 15 per cent.Finally, a comparison of the aqua regia leach atomic absorption spectroscopy (AAS) and fire assay fusion AAS techniques is made.This shows that the mean precision, the ability to obtain the same value, of the methods at 98 per cent confidence is ± 30 per cent and ± 15 per cent respectively. The fire assay fusion AAS method is relatively more accurate than the aqua regia one.

Jan 1, 1984

By N. Del Bel Belluz

Drilling underground in the Grasberg De-watering drifts has routinely hit water aquifers with high flow rates and pressures. Two types of holes are utilized; pilot-holes to probe ahead of the tunnel development to intersect aquifers ahead of the face; and de-watering holes to de-water rock formations that will drain water from the Grasberg pit and allow tunnel development to proceed safely. Recently, rates of 1050 psi static pressure have been recorded with flows from a NQ hole measured at 1350 gpm (US). The water flows can be slightly acidic, necessitating the use of stainless steel collar gear to resist corrosion. These rates were anticipated and contingencies were planned early to deal with these conditions. The collar gear is used to control water flows whereby the water is treated as an important resource. As a result, pm has established procedures to maintain safety of the drill crews, enable coring of the rock and to maintain safety of the miners who are driving the drifts.

Jan 1, 1998

By Juan M. Pestana, Jeremy M. Gasser, Cuneyt Gokmen, Paul J. Sabatini, William Tanner, Daniel J. Woeste

An access pathway and working platform were designed and constructed for equipment access for a Deep Soil Mixing (DSM) pilot study over a coal combustion residual (CCR) surface impoundment (SI). The DSM pilot study was conducted to evaluate slurry mix designs and construction techniques for installing DSM columns up to 95 feet deep. Two-dimensional (2-D) limit equilibrium and 2-D finite element analyses were used to evaluate multiple failure mechanisms including: (i) bearing capacity, (ii) punching shear of mixed ground and underlying CCR, (iii) effect of fluidized DSM columns on working platform stability, and (iv) liquefaction. The analysis results were used to design ground improvement required to increase bearing capacity and stability of the CCR under the proposed equipment access route. A long-reach excavator was used to perform shallow bucket mixing and walk onto the CCR SI atop previously mixed cells following a minimum cure time and acceptance of quality control test results. Prior to mobilizing the DSM rig, a static load test was conducted to evaluate performance of the working platform. Both the access pathway and working platform demonstrated acceptable performance under the design loads during the DSM pilot study. This case study emphasizes the economic and safety benefits that can be realized by appropriately designing critical temporary work items such as access pathways and working platforms in difficult ground conditions. INTRODUCTION A Deep Soil Mixing (DSM) pilot study was conducted at a coal combustion residual (CCR) surface impoundment (SI) to evaluate slurry mix designs and construction techniques for closure design of the SI (Site). Sluicing of CCR at the facility ceased and closure will be initiated based on requirements in the final United States Environmental Protection Agency (USEPA) Rule for Disposal of Coal Combustion Residuals from Electric Utilities, 40 CFR 257, effective October 19, 2015. The proposed closure approach involves constructing a DSM containment structure (DSM Wall) to separate the SI into two areas: (i) a closure by removal area; and (ii) a consolidate and cap-in-place area. The proposed DSM Wall would retain the CCR within the consolidated closure footprint and provide a barrier between the two areas of the SI. The predominant CCR in the SI where the pilot study was conducted were fly ash and bottom ash. CCR materials in surface impoundments are generally soft and saturated as a result of being sluiced into place and can present stability and safety challenges when performing earthwork activities.

Jan 1, 2019

One would anticipate that after 40 years in the mineral industry it would be simple to project the trends at least 5 or 10 years into the future. However the last 20 years, 1950-1970, have been so different in the mineral industry from the years 1930-1950 that I suggest only 20 years or so are relevant to any forward projection.Those, of us that have been about during the last 40 years find it hard to relate the two periods.The first with the depression, low base metal prices, attempts to revive the gold industry, very little export of minerals, and finally World War II and the recovery period.The second, a period of unimagined discoveries and the reappraisal of a wide variety of minerals and metals-iron, coal, bauxite, beach sands, manganese, oil and gas, and nickel, to name but a few.The second period started early in the 1950s and was triggered off by the search for oil in Australia.Rough Range No. 1 was an important milestone in our history because it initiated a series of speculations and the re-examination of much of our thinking about our mineral resources. It lead to the discovery of bauxite and the start of a flourishing aluminium industry.The realization of the extent of the iron ore resources was another, major step and the influx of overseas capital and competence started the large wave of development made effective by the Japanese markets.The momentum of the late 1950s has carried us to where we are today and will undoubtedly carry us further forward in the next few years.All this development in the mineral industry has come at a time when our pastoral industries have reached a difficult period. I have no doubt that if it were not for the mineral industry Australia would at the moment be experiencing one of its blackest eco...

Jan 1, 1971

By Gunderson C. T

The use of carbide tipped integral drill steels and detachable bits is discussed in relation to the means of drilling or cutting employed. It is stressed that only by correct use can the full value of these tools be realised.Factors affecting carbide quality, the design of shanking steels and the requirements and techniques of brazing in inserts are considered.It is essential that the brazed jointing between carbide and steel be strong but ductile. The methods used for the manufacture of carbide tipped tools are briefly outlined.INTRODUCTIONIn recent years the application of tungsten carbide to various mining tools in the mining industry, has developed to the stage where it is now regarded as an essential item in the production of coal and metal ores. In fact it is claimed that certain mining operations would not be possible if it were not for the benefits obtainable from the characteristic properties of tungsten carbide. The advantages of this hardmetal have, to some extent, influenced manufacturers to revise design specifiations of some machines, while againsome machines have actually been designed with tungsten carbide as their basic medium for operation.In general the applications fall into the following three categories:(a) Drilling hard rock by percussive means.(b) Drilling soft rock and coal by rotary means.(c) Coal cuttingThis paper is concerned with tungsten carbide tools associated with these three activities in Australia, the effectiveness of their application and significant points in their design and manufacture.

Jan 1, 1958

By Anton Gronningsater

AT the present time we hear a great deal about organization of labour, collective bargaining, workmen's councils, and company unions; about C.1.0. with its principle of vertical unions and A.F.L., largely based on craft unions; and about provincial and federal laws for protection of labour's right to collective bargaining. What we perhaps hear too little about is corresponding organization of the employers, although it recently is mentioned more frequently. I will only mention W. H. Davis, Chairman of the United States War Labour Board, who has had and is having plenty of experience in this field and has also studied labour conditions in Europe-in Sweden for instance. He has repeatedly expressed the opinion that where employer-employee problems are involved, a thing badly needed in America is organization of employers as well as employees to get some order in the present chaos. With this I agree. I believe a strong organization on one side necessitates a correspondingly strong organization on the other side; that has at least been the experience in the industrialized countries in Europe. I happen to be fairly familiar with conditions in Norway, where they have struggled with these problems for fifty years, and a talk on the history, development, and present state of employer-employee relations in that country might perhaps be of interest as giving a general picture of the development of such relations in the northwestern European countries as a whole. The talk was originally given to the Fourth Year students in Mining and Metallurgy at the University of Toronto. I have changed it somewhat to fit a different audience, but I hope you will make allowances if you now and then are reminded of the school auditorium. I will try to be as objective and factual as possible, but it is probably unavoidable that some of what is said is coloured by personal opinion.

Jan 1, 1943

Uranium exploration over a wide area of the Southern Frame Embayment, South Australia, has defined a number of Lower Tertiary fluvial palaeochannels incised in older rocks. The buried channels contain similar stratigraphicsequences of interbedded sand, silt, and clay, probably derived from the adjacent uranium-rich Olarv Provinee. Uranium mineralization is pervasive within two major palaeochannels, and four small uranium deposits have been found in the basal sands of these channel sequences, at the margins of extensive tongues of limonitic sand.One of the channels is examined in detail with respect to channel morphology, stratigraphy, and rock alteration and the geology and ore controls of the contained uranium deposits are described.A geochemical zonation reflected by variation in limonite, pyrite, carbon, and humic malleI' is defined across one of the deposits. A genetic model is proposed suggesting formation by a uraniferous geochemical cell which migrated down the stream gradient and concentrated uranium on its lateral margins adjacent to the channel bank.

Jan 1, 1978

By C. Gerow

THIS paper is entitled "Some" problems, rather than "The" problems, met in selling coal, since the problems to be met in selling any commodity have to deal with an infinite number of circumstances and conditions. These are believed to be more varied in the case of coal than probably any other commodity. This is due, perhaps, to the fact that coal has been one of the basic materials in the guiding of industrial and national achievement for the past two hundred years. During this time its use has developed from a most haphazard one to uses involving all modern scientific methods, which, rather than simplifying matters as regards the marketing of coal, have added many fresh problems, and these vary according to the particular market served. Since the concern of this paper is primarily the selling of Nova Scotia coal, it is proposed to deal chiefly with some of the specific conditions met in the markets presently served by this coal. For the purpose of discussion, these markets may be considered as divided into three main groups, namely, the Maritime market, the Quebec market, and the Ontario market. THE MARITIME MARKET First of all, let us consider the Maritime market. This is a market which has been regularly served by Nova Scotia coal since coal mining became the first industry in Cape Breton, slightly over one hundred years ago. Conditions as applying to the use of coal have naturally tended to adjust themselves to the characteristics of the coal most readily available, and, therefore, marketing problems are fewer in the Maritimes than in districts where many coals of varied characteristics are offered. Up to recent years, the problems involved were chiefly those of providing satisfactory service insofar as de-liveries were concerned. However, with the speeding-up of manufacturing processes and the necessity of reducing costs to a minimum, users of coal have become interested in obtaining coal that will give the most economical service. It is, therefore, now of importance that the salesman should have full knowledge of the particular conditions applicable to each customer's use in order to deal to the best advantage.

Jan 1, 1936

By I Thin, L Morizzi, C Seymour, G Mungur

Olympic Dam has been investigating mine design options for the South Mine Area (SMA), which will continue using the existing sublevel open stoping (SLOS) method. The SMA is an undeveloped mining area, located south of the existing underground mining areas currently in production at Olympic Dam. The SMA study reached the stage where geotechnical inputs were required for stope design, infrastructure location and ground support forecasts. A large database of geotechnical data was collected to inform open pit designs for the ODX (Olympic Dam expansion) project (resulting from 659 drill holes). This geotechnical data has since been reprocessed to align with design inputs required for the SLOS mining method. The result has been the construction of a preliminary three-dimensional mining rock mass model (MRMM) that has been incorporated into preliminary stope mine design and infrastructure layout assessments, which have taken into account the predicted prevailing ground conditions.As with any model, it is necessary to improve the confidence in its predictability; therefore the model must be calibrated. The preliminary SMA MRMM was no exception. First pass calibration was possible with results from underground geotechnical window mapping from exposed rock mass conditions in the lateral development and surface geotechnical holes for ventilation shafts.The SMA project continues to advance and has started a program of resource drilling. Selected holes have been identified that target data limited areas. This will ensure that the data gaps are infilled in order to maintain the required data density required to improve the model confidence. In addition, further underground window mapping in the SMA will provide ‘mine scale drill hole’ data that can be used to either update the MRMM or as part of planned future calibration. Stope performance data from stopes will provide further valuable data for calibration purposes.The proposed paper will present the process and findings that have been followed in order to establish a well calibrated geotechnical model that can be used with an acceptable level of confidence in the ongoing refinements of the mine design and planning process for the SMA.CITATION:Thin, I, Morizzi, L, Mungur, G and Seymour, C, 2016. Building and calibration of a geotechnical model for sublevel open stope design at Olympic Dam, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 523–532 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By K. Blaski

his paper reports an investigation aimed at optimizing the compaction of granulated hard-metal powder for the production of cutting tool inserts. The optimal compaction is that which yields optimal shrinkage during sintering, i.e. minimum porosity in the sintered part. Extensive compaction tests on 23 different hard-metal powders have been carried out and have shown that the ideal ?green density? of a hard-metal compact, i.e. the density after compaction, increases linearly with the apparent density of the powder. On the basis of this result, an equation has been derived, which allows one to predict the optimal shrinkage that a hard-metal compact undergoes during sintering once the following data are known: the required sintered density, the volatile content of the powder and the apparent density of the powder. Since these data are available to the tooling designer, this equation allows one to design tooling for the compaction of hard-metal, which leads to optimal shrinkage

Jan 1, 2007

By P Holtham, K Duffy, W Valery, A Jankovic

As high grade ore deposits are depleted, remaining deposits are generally lower grade and require the mining and processing of larger volumes of material per tonne of product. These low grade deposits often contain a large proportion of barren gangue. Pre-concentration aims to remove this barren material at as coarse a particle size and as early in the process as possible. This has the potential to reduce processing costs, energy and water consumption, increase production and improve resource utilisation.There are several technologies that may be applicable for pre-concentration. This paper looks specifically at bulk ore sorting and how it can be integrated into existing or new mining operations to improve profitability and reduce environmental impact. Bulk ore sorting is the separation of barren gangue from a fully loaded conveyor belt based on the grade as measured or inferred from a sensor measurement. It may be used to increase the production rate through fixed plant capacity, or increase production and/or reduce the size of downstream processing equipment in Greenfield operations. Marginal ore sub-economic reserves may be upgraded, making them economic to treat and improving the resource utilization. Bulk ore sorting could also be used to reduce dilution and ore loss in mining operations by improving grade control, or to separate ore types to treat via different process routes. Various applications of bulk ore sorting are discussed in this paper, and three cases are investigated considering the impact on the overall operation and the associated benefits.CITATION:Duffy, K, Valery, W, Jankovic, A and Holtham, P, 2015. Integrating bulk ore sorting into a mining operation to maximise profitability, in Proceedings MetPlant 2015, pp 273–287 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Tianjiao Luo

The electroless copper plating process for continuous carbon fiber using CuSO4?5H2O as the main salt and formaldehyde as reducing agent was experimentally studied, including the effects of pH values and concentration of chelating agents, stabilizing agents and reducing agent on the electroless plating process. The surface morphology and the composition of coating were investigated by means of Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), and deposited the coating thickness was measured by way of dissolution. The results indicated that the pretreatment of carbon fiber before plating was so important. This pretreatment could prevent the formation of the black cores, furthermore, it could form many active absorption cores with Ag as the center on the carbon fiber surface. Used the optimized parameters in this process, which led to a stable solution for plating, a homogeneous copper coating was conducted with the carbon fiber plated with favorable mechanical performance and high adhesion strength.

Jan 1, 2006

By Christopher Mark

Multiple seam interactions are a major ground control hazard in many U.S. underground coal mines. The two most common types are: ? Undermining, where stress concentrations caused by previous full extraction in an overlying seam is the primary concern, and; ? Overmining, where previous full extraction in an underlying seam can result in stress concentrations and rock damage from subsidence. The National Institute for Occupational Safety and Health (NIOSH) has completed a major study aimed at helping to identify the location and likely severity of these interactions. In the course of field visits to mines throughout the U.S., more than 300 multiple seam case histories were assembled into the largest data base of multiple seam case histories ever collected. These data were analyzed with the multivariate statistical technique of logistic regression. The study also employed LaM2D to estimate the multiple seam stresses, ALPS and ARMPS to determine pillar stability factors, and the CMRR to measure roof quality. The study resulted in the development of a computer program, called Analysis of Multiple Seam Stability (AMSS), which can help mine planners to evaluate each potential interaction and take steps to reduce the risk of ground control failure. AMSS first evaluates pillar design by calculating the single seam Stability Factor (SFSS) using ALPS or ARMPS. It also automatically generates a LaM2D analysis that provides the additional multiple seam stress so that the final, multiple seam SFMS can be determined. The second part of the AMSS procedure builds upon the statistical findings that overmining is much more difficult than undermining, isolated remnant pillars cause more problems than gob-solid boundaries, and weaker roof significantly increases the risk of multiple seam interactions. AMSS quantifies these effects and predicts the outcome in terms of three levels of risk: GREEN (where a major multiple seam interaction is considered unlikely), YELLOW (where adding a pattern of cable bolts or other equivalent supplemental support could greatly reduce the probability of a major interaction.), or RED (a major interaction should be considered likely, and it may be desirable to avoid the area entirely).

Jan 1, 2007

Lignite deposits of Central Otago Miocene Dunstan Formation accumulated on a broad alluvial plain and on deltas that flanked a large freshwater lake. The regional subsurface distribution and configuration of the lignite-bearing strata are identified within the context of depositional systems and placed into a genetically defined stratigraphic framework. The stratigraphic and depositional models constructed, should form an integral part of the geological assessment process to guide future regional or mine based lignite drilling programmes. Further testing and evaluation of the commercialy important lignite deposits in the Blackstone and Roxburgh Coalfields are required to adequately characterise the lignites and their geological setting, particularly to select methods of mining and wise uses of the lignite.

Jan 1, 1992

By N. Behnood

"This paper describes how material selection, quality assurance, and failure investigation play important roles in the efficiency and safety of mining and metallurgical operations.INTRODUCTION Material selection, quality assurance, and failure investigation are all complementary elements of materials engineering in the application of materials technology for failure prevention. Based on commodity price increase of 300% between 2002 to 2013 [1] and increased cost ofcapital projects and operation, equipment failure, which in some cases causes complete shutdown of the operation, becomes a vital importance in mining and metallurgical plants. The following sections present a number of examples from many failure cases experienced by the author during his three decades of work as a materials engineer in the mining industry."

Jan 1, 2015

The excavation of ramps and tunnels often requires high-speed development with (or without) the use of high-energy mining equipment such as loaders, dump trucks, TBMs and roadheaders. This high-speed development creates a challenge in terms of providing a safe and productive working environment. For example, heat from continuously exposed surrounding rock, heat from broken rock, heat generated by mining equipment, potential in flows of hot ground water, pollution from associated diesel equipment and the distance of the advancing face from fresh through-ventilation all have to be taken into account when designing ventilation systems for high-speed ramp and tunnel developments. This paper discusses methods of achieving acceptable environments at the face and along the length of the tunnel. The methodology has been successfully implemented in the development of long (up to 20 km) TBM drives in the Lesotho Highlands Project and in mining projects in hot rock using drill and blast methods as well as mechanized methods using continuous miners and roadheaders. The determination of heat loads includes calculation of the heat flow within the surrounding rock, evaluation of the operating cycle of the equipment and the contribution to the overall heat load of the broken rock as it travels out of the tunnel. The determination of heat loads from surrounding rock in new tunnels required a modification of the algorithms generally used for established excavations. The paper also examines the use of, for example, mobile duct and fan systems to ensure that fresh air is delivered to the specific areas where workers are located.

Jan 1, 2000