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By Yaw Boadi, Andrew McCallum, Sandy Gray, Yavuz Atasoy, Peter Wemyss

"Various full-scale test programs and installations of the InLine Pressure Jig (IPJ) have provided evidence that pre-concentration of the difficult to leach sulphide mineral through gravity can provide significant increases in economic recoveries. The continuous gravity concentrates are intensively treated either by re-grinding or Intensive Cyanidation. Data from various mine sites worldwide is presented. Treatment of complex ore bodies with this low cost methodology may render previously uneconomic ore bodies financially viable and assist in the recovery profile of transitional ore.INTRODUCTIONThe use of gravity is made extremely attractive in complex ore situations due to the low cost of operation, typically a few cents per ton operating cost and lack of chemicals.Gold mines which suffer from poor recovery due to complex mineralogy such as Stibnite, Arsenic, Carbon, Telluride, Silver and other pacifying agents such as Iron, which can form coatings, can all benefit from the process proposed in this paper. The key issue is not overall recovery as much as one of economic recovery. The key to this is maximised recovery at the lowest possible capital and operating cost. Other options such as flotation are reviewed but are not seen in many instances to be the panacea due to issues discussed in the paper. The use of the InLine Pressure Jig in the re-circulating load of the milling circuit is a cost effective means of recovering a sulphide/gold concentrate containing the complex mineral assemblages which require re-grinding and intensive leaching for optimised gold recovery.The benefits of Jig Assisted Grinding (JAG) are many and the challenge over the past years has been developing, understanding, implementing and evaluating the benefits of various flowsheet models. This has involved the reconciliation of results in plant scale trials back to the original laboratory test program. The following paper outlines the insights gained in this area through extensive work carried out by many people across both laboratories and plant sites in Australia and overseas. The examples in this paper are some of the work carried out on a few selected sites but similar work has been carried out on other sites such as Penjom, Granny Smith and Agnew. This work has eventuated in several installations which we believe have great importance in the future of the gold processing industry. They will lead the way forward to the modern all-gravity plants of the future.Compared to flotation, for the recovery of sulphides, gravity is a simple option. The simplicity generally translates to low capital and operating cost."

Jan 1, 2004

By J. Utt

Recent developments in circulating fluidized bed (CFB) once-through supercritical technology (OTSC) have enabled this technology to be offered as a utility-scale alternative competing head-to-head with pulverized fuel (PF) OTSC offerings. One clear example is the CFB supercritical unit at the Lagisza Power Plant in Poland, owned by PoludniowyKoncernEnergetyczny SA (PKE). This unit has now been in commercial operation for three full years, exhibiting very good performance, and has validated Foster Wheeler?s performance model at this utility scale as well as for units in the 600 MWe and 800 MWe size ranges offering net efficiency of ~43 per cent (LHV basis). This operating unit has also proven the use of the world?s first FW/BENSON? vertical-tube OTSC low mass flux technology. Since the Lagisza original international tender specified OTSC PF technology, it is important to note that the alternative selection of CFB OTSC technology over conventional PF technology is of historic significance, not only for the validation of the CFB supercritical platform as a viable alternative to conventional PF technology, but it also positions the CFB OTSC with fuel flexibility for offering of sizes up to and including 800 MWe units. This paper explores the differences between CFB OTSC technology and standard PF OTSC in utility power generation. Selection criteria, fuel burning range in both technologies, and other selection drivers are discussed. Economic analysis of both technologies, based on existing cases, is also provided. Also discussed are the technical advantages and uses of each technology. Foster Wheeler has recently been awarded a contract for four units of CFB OTSC technology, which utilizes a 2 on 1 configuration of two 550 MWe CFB OTSC boilers on two single 1000 MWe turbines. Essentially this provides a fuel-flexible low-emissions alternative to a 2 × 1000 MWe solid fuel power block.

Jan 1, 2012

During an eight month period, January to August 1978, nine bore holes were drilled in the Mikonui River gravels. On account of two rebores required from near bottom, the number of bores is in effect 11. Just on 1300 feet were drilled with an average depth of 120 feet. Depth varied from 102 feet to 133 feet. Penetration on average per hole value, varied from 7.4 to 16.4 feet per day. Gold values were even more erratic. Drill rig used was the Keystone churn drill manufactured locally by the Dispatch Foundary. It is skid mounted and requires a crew of two persons.

Jan 1, 1979

By K. M. Li, Y. D. Zhang

The selection of stripping dragline is a complicated problem. Several factors, such as the deposit buried conditions, the demand of mine production rate, cast blasting result, the mining/stripping operation method and parameters, etc. may comprehensively influence the optimal selection of technical specifications of the dragline. Under these circumstances, the basic thinking and procedures for dragline selection are put forward as follows. •Step 1—Initially estimate the dragline annual stripping rate and stripping bench height according to the annual coal production rate and advancing speed of mining front. Then the feasible alternatives of dragline sizes can be calculated and selected from the existing dragline series. •Step 2—A computer simulation model is developed to simulate the dragline stripping operation, to obtain a series of working face parameters, then to select the best dragline alternative. This step can be interactively iterated until the satisfactory results are obtained. •Step 3— Sensitivity analysis can be done with the systems simulation model by changing the stripping bench parameters, e.g. stripping bench height and cut width, etc. to verify and modify the selection results if necessary. The mathematical model for dragline stripping simulation has been set up. The flowchart of the model is shown. A case study for a large surface coal mine with annual production rate of 16 Mt/a is followed. The dragline bucket capacity and operation radius, stripping bench height and cut width as well as other parameters are comprehensively optimized and selected. Keywords: Open cast, dragline, specification, selection, cast blasting

Jan 1, 2003

By J. Bennetts

As part of its mission to develop technology that will help increase the supply of critical and strategic minerals from domestic resources, the Bureau of Mines has investigated methods for beneficiating platinum-group metal ores from the Stillwater complex, Montana. This report presents the result of a bench-scale study employing froth flotation to recover a sulfide concentrate containing platinum-palladium values from a mineralized gabbro. Best results were obtained with a flotation scheme utilizing a mercaptobenzothiazone collector and sulfuric acid. Rougher concentrates containing approximately 11 oz Pt-Pd/ton and 90 pct of the metal values in the ore were obtained. Subsequently, cleaner concentrates containing approximately 26 oz Pt-Pd/ton and between 80 to 85 pct of the Pt-Pd values in the ore were prepared.

Jan 1, 1980

A dedicated tunnel construction version of the Caterpillar 328D LCR compact radius excavator is proving highly productive on the A9 Autoroute construction project near Visp, in Switzerland. It is the first machine of its kind to operate on a Swiss contract and uses a special dedicated front attachment designed and constructed by German Caterpillar dealer Zeppelin. The machine offers a powerful, stable and compact solution for tunneling contractors. A rear overhang of just 305 mm (12 in.) provides a tail swing radius of just 1.9 m (6.2 ft). The 328D LCR is ideal for the restricted working areas within a tunnel construction site. The machine is equipped with the wide tracks from the 330D L conventional crawler excavator, ensuring maximum stability when operating. In addition, the boom mounting has been moved further toward the center of the machine for the tunnel model, creating an increased lift capacity over the front end compared with a standard 325D L. The boom itself features a robust box section construction, with high-strength steels, additional supporting struts and reinforced bearings for maximum durability. All pins have hard-chromium plating for optimum protection against wear. Stick digging force is a powerful 134 kN, with up to 212 kN of bucket digging force available, for maximum penetration in blasted material. The 328D LCR is also equipped with a heavy-duty dozer blade as standard. This ensures outstanding stability when working and providing a useful secondary tool for clearing and leveling within the jobsite. Two 45° tilting mechanisms in the boom construction, allow the boom to be swung to 45° on either side of the machine. So the specially designed attachment linkage provides increased rollback for access to the roof of the tunnel. A Caterpillar CW45S mechanical quick-coupler allows rapid changes between specialist tunneling attachments, standard Caterpillar buckets and a range of Caterpillar work tools. The machine is powered by a Caterpillar C7 diesel engine. This six-cylinder EU Stage IIIA diesel motor [ ] offers 8 percent more power than its predecessor, with 140 kW (190 hp) available at just 1,800 rpm. Caterpillar?s ACERT combustion technology results in lower fuel consumption and reduced exhaust emissions. However, the tunnel machine is also equipped with a diesel particulate filter as standard, to further cut exhaust gases within the tunnel working. The 328D LCR is designed for use in transport tunnels of 6.8 m (22.3 ft) in height. With the tunneling boom in place, the machine has an operating weight of 42,540 kg (93,783 lbs), yet retains a transport height with the tunnel boom of just 3.9 m (12.8 ft). Transport width with 600 mm (23.6 in.) track shoes, is just 3.2 m (10.5 ft). On the A9 tunnel contract, the machine is being used by a consortium of Swiss and Austrian companies working for the canton of Valais? Routes Nationals Construction (RNC) department. The 31.8-km (19.7-mile) A9 Autoroute construction project will connect Sierre in the west and the town of Brig to the east. The tunnel that is bypassing the town of Visp is just one of a number along the mountainous route.

Jan 1, 2009

By Alla D. Mah

The need for more and better basic thermodynamic data for the oxides of many of the rare metals is evident to anyone who attempts thermodynamic calculations involving these substances. In continuation of a Bureau of Mines program to meet this need, this paper reports new experimental values of the heats of formation at 298.15° K. of the hexagonal crystalline variety of germanium dioxide and germanium dioxide glass. The values were obtained by means of combustion calorimetry and sodium hydroxide-solution calorimetry. The calorimetric results also made possible the derivation of values for the heat and entropy of fusion of hexagonal germanium dioxide at its melting point. The newly measured data were combined with previously known entropy and high-temperature heat content values to obtain heats and free energies of formation of germanium dioxide (in the hexagonal crystalline, glassy, and liquid states) over the temperature range from 298.15° to 2,000° K.

Jan 1, 1962

This Bureau of Mines publication presents an overview of mine electrical power systems research currently being conducted by the Bureau. The papers, given at a Technology Transfer Seminar, emphasize the increasing importance of research related to the safety considerations of underground coal mine electrical systems. Selected topics are included that summarize results of research in the areas of electrical shock prevention, explosion-proof enclosures and load centers, discriminating circuit breakers, and trailing cables. Other topics discussed at the seminar are published as separate sections of the Bureau of Mines Hand- book "Application Notes--Mine Electrical Power Systems."

Jan 1, 1982

By D Bruggemann, F Sereshki

There has been an ongoing research on coal and gas outburst for the past two decades at the School of Civil, Mining and Environmental Engineering, University of Wollongong. Research study began with a humble beginning, initially conducting basic laboratory studies on the coal and gas properties, progressing into the determination of gas content of coal by sorption technique and the effect of gas pressures on coal strength. The present laboratory facilities and research interests are extended to include the study of coal permeability and shrinkage properties and their effect of gas drainage characteristics with respect to gas type, and pressures. All the changes are examined with respect to changing in-site geological conditions of the coal deposit investigated. The aim is to provide a long-term support to industry in establishing a data bank for Australian coal deposit characteristics and properties.

Jan 1, 2005

By Marianne Snedeker

In September 1985 we published a questionnaire asking about the content of MINING ENGINEERING and about your interests. By Dec. 10, our cutoff date, we had 430 responses, representing about 1.5% of the 28,238 people who received the September issue of ME. In the data that follow the tabulation and percentages are based on the number of individuals who responded to the particular question. About ME Through responses to the questionnaire, we were hoping to learn more about you, your interests, and how the magazine could better serve you. Those of you who responded told us something positive - you look at or read the magazine. Of the 430 respondents, 428 or 99.5% indicated that they had read or looked through the July and/or August issues. Those of you who refer to the magazine once are 207 or 48.5%. Those of you who refer to the magazine two or three times are 193 or 45.2%. Those of you who refer to the magazine four or more times are 27 or 6.3%. How much time do you spend reading the magazine? Of those responding to this question: 64 spent up to 1/2 hr 15.0% 224 spent up to 1 hr 52.6% 115 spent up to 1-2 hr 27.0% 23 spent more than 2 hr 5.4% In an informal survey among our staff, we determined that most people spend 1/2 to 1 hr reading magazines to which they subscribe at home. Does that match your experience? Many of you, 335 or 79%, clip your magazine for further reference. Also, many of you, 313 or 73.6%, do not pass your copy on to another reader, indicating that you are clipping it or receiving the magazine at home. Those magazines that are passed on reach: 1 person 3 0.7% 2 people 64 15.1% 3-5 people 34 8.0% 5 or more 11 2.6% Answers to what portions of the magazine you find useful indicated that the top three were Industry Newswatch, feature articles and Technical Papers; see Table 1. The "other" category included advertising - display, classified, Employment, and Professional Services - Washington Survey, New Products, Free Literature, book reviews, technology news, and Coming Events and Short Courses. We asked your appraisal of the technical level of the magazine. Of those responding, 39 or 9.1% indicated that it is too technical, 55 or 12.8% indicated it is not technical enough, and 335 or 78.1% judged it to have the correct technical level. In response to the question about whether you like to read an occasional feature that is not technically oriented, 21 or 5.1% said no, but an overwhelming 94.9% (393) said yes. Of the specific

Jan 1, 1986

Paper written on project work carried out in partial fulfilment of M.Sc. (Chemical Engineering)degree Identification of non-linear systems can be a daunting task and in the process industries the problem is complicated considerably by the presence of noise from various sources, non-stationarity of the data and intermittence, such as observed in particulate flows. Traditional methods, such as frequency analysis and linear model-ling do not handle these systems well. Similar problems arise with the application of non-linear theory developed over the last few decades, where much of the analysis depends on embedding of the data in a phase space or pseudophase space, since these methods were not originally designed to deal with noisy systems. In contrast, singular spectrum analysis is a method which can be used to identify structure and distinguish noise from important information in multivariate data, such as the trajectory matrices of time series measurements. It provides an orthogonal basis onto which the data can be transformed, so that components of the time series can be investigated individually. With Monte Carlo methods, the components can be compared with those from linear surrogate data in order to identify possibly non-linearities in the data. In this paper, this versatile technique is briefly explained and illustrated by means of case studies.

Jan 1, 2003

By Frank L. Hess

"New England" and "granite" if not synonymous are at least associated terms. Where there are granites that are not deeply eroded there are usually pegmatites, the most erratic of rocks, and of them New England has a full portion. Many of the New England pegmatites contain the rare alkalis - lithium, rubidium, and cesium. however, the same in homogeneity of the earth's crust that has made the New England pegmatites unusual, in that so many of them contain the rare alkalis, has likewise made the distribution of the rare-alkali minerals sporadic even in those pegmatites, and most contain only enough to furnish collectors with more or less ornamental and uncommon minerals. New England has long had numberless collectors of minerals, and the mineralogists of its various schools have published many papers on the pegmatitic minerals, including those of the rare alkalis, but none of the papers have dealt with estimates of quantities. In this paper we have tried to place the emphasis on quantity rather than on mineralogy.

Jan 1, 1943

By M. Perolo, A. Contini, E. Ramelli, G. Borgonovo, L. Locatelli

This paper presents the ground settlement monitoring system used during the construction of two tunnels bored by two EPB TBMs, beneath the existing and active railway embankment in Bologna (Italy). The tunnels run close to large buildings and beneath bridges and other infrastructure. Data are collected from remote total stations and from electro levels installed directly on the railway tracks. The automated monitoring system acquires and analyses data then sounds an alarm in the event that there is a problem. Alarms are sent out in case of excessive tilt or settlement. Data is provided through a dedicated web application for multiple-party access, to gather, manage and store monitoring data.

Jan 1, 2007

By Lottrey A. L, Sowerby B. D, Cutmore N. G

On-line monitoring of low rank coal quality during input to a process has the potential to provide benefits through: ò anticipation of coal quality variations prior to utilisation; ò provision of a tool to help determine the influence of coal quality on process behaviour, and ò provide a direct measure of coal quality for pricing. Moisture and ash are the two most significant coal quality parameters for combustion. They determine the energy content which can be derived from the coal and the problems arising from the presence of ash in the process (eg ash fouling, corrosion, erosion, particulate emissions and ash disposal). Extensive pilot-scale testing and full-scale experience has shown that specific coal/ash constituents (eg Na2O/ash ratio, acid-soluble aluminium, silica, sulphur contents, etc) are also important for the behaviour of Latrobe Valley brown coal during combustion, ash formation, deposition and removal of ash in precipitators and furnace ash hoppers. This paper discusses the range of on-line analysis techniques which have been investigated and their application to low rank coal analysis. Preliminary results from a joint SECV/CSIRO project which aims to develop two separate advanced instrument systems are also presented. These systems are based on: ò microwave attenuation and phase shift - for direct determination of moisture content; and ò inelastic neutron scattering - to provide total hydrogen, carbon, chlorine and ash contents, with potential for calculation of moisture content, specific energy, sodium content and Na20/ash ratio using correlations.

Jan 1, 1992

By Klaus Rieker

Over the last 30 years Wayss & Freytag Ingenieurbau AG has gained a lot of experience in mechanized tunnelling on various major projects. During this period most important developments concerning the machine technology for EPB- and Slurry-Shields have taken place. Since the first application of a hydro shield for the Wilhelmsburg Collector project in Hamburg in the early seventies, several stages of development have led to the current state-of-the-art in mechanized tunnelling. The continuous improvement of TBM techniques allows the execution of high quality tunnelling, particularly with regard to maximum safety and efficiency. The practical experience of the construction companies is of essential importance in order to continue further development and improvement.

Jan 1, 2005

The importance of the Broken Hill mining field may be gauged from the fact that since the discovery of the ore-body in 1883, till the end of 1931, approximately 43,000,000 tons of ore have been raised.The lode covers a length of 31 miles, and in places is upwards of 300 ft. in width. The ore, as at present mined, consists of an intimately blended mixture of lead and zinc sulphides with silver and gangue minerals.Structurally the lode conveys the impression of a huge longitudinal arch (when viewed from the east or west), having its apex or crown near the centre of the field, in the leases of the Broken, Hill Proprietary Co. Ltd., where the lode outcropped at the surface.The minimum depth of the lode in the Proprietary mine was some 500 ft. from the surface, but huge undulations, having an average pitch of 45°, carry the extensions of the arch gradually deeper, to those places where active stoping operations are now in progress in the workings of the North mine at one extremity, and the South and Zinc Corporation mines at the other. The depth of the lode from the surface, as exposed at present, is approximately 1700 ft. at these extremities.The structure and physical character of the ore-body, and its containing walls, are so complex and varied that almost every type of mining problem is met with.

Jan 1, 1932

By James A. Schneider

Selection of resistance factors within Load and Resistance Factor Design (LRFD) requires accurate assessment of uncertainty and bias in load and resistance. To date, many studies have focused predominantly on the assessment of uncertainty, while the potential for bias appears to be the dominant factor in design for consistent levels of reliability under a variety of situations. Bias comes from factors which have been ignored in design method development but significantly influence resistance when extrapolating from conditions typical of databases to those at a given site. Uncertainty and bias can be quantified as the coefficient of variation and mean (or median) of a data set, respectively, for statistical assessment of load and resistance factors. This paper first presents an overview of statistical assessment of resistance factors, and then discusses factors that influence uncertainty and bias when extrapolating to situations outside of conventional databases of driven pile axial capacity.

Jan 1, 2009

The widely accepted kinetic model for the gaseous reduction of hematite is critically examined. The formation of the wustite layer during internal reduction cannot be explained in terms of solid-state diffusion. Present evidence indicates the existence of a micropore system in the wustite adjacent to the magnetite with the gas/solid type of reaction occurring not only at the iron/wustite interface but also at the wustite/magnetite interface. During the partial reduction of dense hematite pellets, in a controlled atmosphere, porous magnetite and wustite are formed as products. The mean pore size, as measured by mercury injection, increases with time at constant temperature and with temperature increase over the range 6500C to 950°C. The sizes of the pores indicate that Knudsen diffusion is the principal gaseous transport mechanism across thick layers of magnetite or wustite.The kinetics of the gaseous reduction to iron are consistent with a mixed control mechanism involving the interaction of gaseous diffusion effects with a first order reversible chemical reaction at the iron/wustite interface. Because of the larger pore sizes in the iron layers, ordinary molecular gaseous diffusion must be the principal transport mechanism. The usual experimental methods used for establishing the validity of chemical rate ~ontrol are incapable of differentiating between the mixed control- mechanism and exclusive chemical control.Some implications of mixed control kinetics are developed, including a predicted independence of rate on reducing gas pressure at higher pressures.INTRODUCTIONAn extensive literature review of the reduction of iron oxides has been compiled recently by Themelis and Gauvin (1962). From the large number of papers published and the widely divergent opinions of workers in this field, it appears that a simple unified quantitative analysis of reduction kinetics is not possible. The aim of the present paper is to show that a major cause of confusion is due to the attempts of many workers to interpret experimentally observed reaction rates in terms of a single rate controlling mechanism without due regard to other rate processes which must occur simultaneously.Some of the differences in behaviour reported for particles...

Jan 1, 1964

By C Doblin

Any value addition to the mineral sands in the Murray Basin (Australia) will generate waste that needs to be disposed of safely. For example, conversion of ilmenite and synthetic rutile to titania (TiO2) pigment would generate large amounts of environmentally undesirable elements. Processing of U+Th containing zircon sands to zirconia or to higher purity zircon would generate a low-level radioactive waste. In this study it is proposed that one way to circumvent the waste problem could be to contain such waste in magnesium-based (Sorel) cements. Containment of waste in magnesium cements is an attractive idea especially for the mineral sand processing companies that could operate in the Murray Basin in the future, because the required magnesium oxide and magnesium chloride may be made cheaply from the saline waters encountered during mining operations. The magnesium cement production process is also far less energy intensive than the Portland cement production process. The results of this study indicate that mixing a waste stream with a slurry of magnesium cement before being discharged to the disposal area would contain the waste in a æconcrete-likeÆ structure, resistant to dispersion by wind and moderate rain. However, some loss of strength and increased leaching of impurities, Mg and Cl could take place in wet climate areas. Ongoing research is being concentrated to develop a new process for making water-resistant magnesium cement.

Jan 1, 2002

Flat jack stress determinations in selected colliery roadways have revealed a range of measured stress from 330 lb/sq. in. tension to 3,750 lb/sq. in. compression. Photoelastic examination of loaded plastic and actual rock model mine openings has shown that the primary horizontal stress required to attain these measured stresses would be from one to three times the superincumbent vertical load.Examination of roof movement with a borehole extensometer and a series of anchors at various horizons to 30 feet in a vertical roof borehole showed that when a standing face was advanced the roof movement was practically confined to the lower two feet. The majority of this movement occurred during the 36 hours after mining at this face commenced.The use of a radioactive isotope and a scintillation counter in a pair of parallel boreholes is a sensitive and accurate method of roof bedding plane crack detection.INTRODUCTIONA knowledge of strata stresses is required to understand the deformation of an underground opening and, in particular, the roof behaviour. It is the aim of investigations currently being conducted by Australian Coal Association (Research) Ltd. to determine the stress existing around mine openings and the location and magnitude of roof movement.STRATA PRESSURE MEASUREMENTMost measurements of strata stress are performed at the surface of underground openings and the majority measure the change of strain resulting from stress relief. The accuracy of the measured value of stress depends upon knowledge of the rock modulus of elasticity. The flat jack method has the advantage that strain relief is restored by a measured stress applied directly by the jack. The rock modulus of elasticity can also be determined.

Jan 1, 1963