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By S. Vennos

As a result of Synopsis 73-16 Dynadyne responded with an unsolicited proposal offering the Bureau of Mines to develop an ultra-low volume coal mine dust personal sampler. In the ensuing technical discussions the choice of a desirable volumetric rate became a focal point. While, the initial proposal was based on a volumetric rate in the area of 50 cc/min the Government expressed interest in a variety of mass flow rates ranging from 50 cc/min to 2000 cc/min. The physical characteristics such as weight, volume and configuration of a personal sampler are to a large extent - dependent on the operating volumetric rate. It became readily apparent that the optimum size of such an instrument as a function of volumetric rate was not known and that a study of the choice of optima was essential prior to beginning the development, Hence, the Government authorized a two phase approach to this project. Phase I was to include a Technical Evaluation Study of optimum characteristics in the range between 0. 1 to 2. 0 lpm. Based on these findings and in consultation with MESA personnel, the Bureau of Mines was to authorize the second phase that is, the development. Phase II, was to include the drawing of a set of performance specifications stating among others the desired operating volumetric rate. In this report, every effort was made not only to present the actual work done over the course of this development, but to reflect also our engineering "thinking" providing answers as to the "why" we preferred certain solutions over others. We believe that this added dimension is not only useful for the Government official evaluating this report, but also that the Government is entitled to it providing the official with an educational content useful in avoiding future costly repetitions of similar situations.

Jan 1, 1975

By B A. Mowat, T M. Leach

The Morobe Goldfield inPapua New Guinea has produced in excess of 120 tonnes of gold from predominantly alluvial sources. Hardrock gold has been mined historically at Wau (23 t) and Edie Creek (4 t) and geological resources have been established at Hidden Valley (78 t), Kerimenge (36 t) and Hamata (30 t).Numerous prospects have also been identified within the goldfield. Primary gold mineralisation is related to intrusion of dacitic to andesitic Edie Porphyry (2.4 to 3.8 Ma), often with associated diatremes, which have intruded along major regional structures. A full spectrum of deposit styles from proximal (mesothermal) to distal (epithermal) to the porphyry source is recognised. The transition between the proximal and distal styles is recognised both between deposits and within an individual deposit. The deposit styles should be termed porphyry related gold mineralisation rather than given the generic epithermal and mesothermal labels.   It is proposed that magmatic fluids which evolved from parent melts to the high level Edie porphyry stocks mixed with convecting meteoric fluids and were channelled along major structure and diatreme contacts. Proximal to the intrusives, gold mineralisation is associated with deposition of pyrite-hematite-quartz+/-magnetite-gold (Hamata) and pyritebasemetals-quartz-gold (Wau). The mineralising fluids were hot, and periodically saline due to pulses of magmatic fluid. Gold is non-refractory and occurs as 20 to 30 micron blebs within the pyrite.   More distal from the intrusives or under late cooler conditions, mixing of cool dilute meteoric and magmatic fluids resulted in gold deposition associated with arsenic rich pyrite-and arsenopyrite-mineralisation (Kerimenge, Hamata and Edie Creek). Gold is refractory and occurs within the sulfides either as sub-micron inclusion or within the lattice.   CO2 and H2S gases which evolved off the upwelling hydrothermal fluids as a result of boiling and pressure reductions, condensed within superficial groundwater and formed cool oxygenated bicarbonate fluids. These fluids percolated back down the structures depositing manganocarbonate in the upper parts of the hydrothermal system. At deeper levels in the system mixing of the descending bicarbonate fluid with upwelling mineralised fluids deposited manganocarbonate-quartz-sulfides nonrefractory gold (Hidden Valley, Wau and Edie Creek).   At Kerimenge the cool bicarbonate fluids have also quenched a late stage magmatic fluid rising along high permeability structures. The quenching has resulted in deposition of non-refractory gold mineralisation associated with hessite (Ag2Te)-tennantite-chalcopyrite deposition.   Within the Morobe Goldfield, a transition from deeper level pyrite-quartz+/-hematite-magnetite to intermediate level quartz sulfide and quartz-carbonate-sulfide deposition to upper level, massive manganocarbonate deposition is recognized. Gold mineralisation can occur within all levels up the system.

Jan 1, 1995

By Joseph A. Vanous

The inductive communication system was developed under this contract for use in the hoist of deep mines. This program was a four phase program with experimental dual frequency equipment resulting from Phase I, emergency single frequency equipment developed under Phase II, and equipment documentation required under Phase III. An additional emergency system was provided under Phase IV.

Jan 1, 1976

By M. du Plessis

This paper describes the evaluation of a limit equilibrium model to simulate the behaviour of crush pillars in platinum mines. An analytical model was derived to calculate the residual average pillar stress (APS) values of the crush pillars. The values predicted by this model were compared to the numerical values obtained from TEXAN simulations. In general, the limit equilibrium model appears to be very attractive for simulating pillar failure as the gradual crushing of the outside of the pillar and the transfer of stress to the intact core can be replicated. The value of the TEXAN crush pillar model was further demonstrated by simulating an idealized layout with crush pillars between two adjacent panels. The simulations illustrated that oversized pillars will not crush close to the face and this may lead to seismic failure in the back area. An important finding of the study is that closure measurements may prove to be a very valuable diagnostic measure in crush pillars layouts. Distinct differences in magnitudes of closure were simulated for a scenario where the pillars crush as expected, compared to the scenario where an oversized pillar is left. Experimental closure data collected in a crush pillar stope provided further evidence regarding the value of closure measurements in these layouts.

Jan 1, 2011

By T. W. Beck

Overexposure to respirable dust remains a widespread health hazard to roof bolter occupations in underground coal mines. Recently implemented mist drilling technology was evaluated for its effectiveness in controlling respirable dust exposures for roof bolting personnel. This work presents the findings from NIOSH field and laboratory studies comparing respirable dust levels on mist drilling roof bolter machines to dust levels measured on machines using a conventional vacuum drilling system. Gravimetric and instantaneous respirable dust samples were collected for multiple drilling cycles. These dust measurements were used to assess the potential dust control capabilities relative to conventional drilling. Controlled laboratory tests found 0.3 mg/m3 more respirable dust with mist drilling than with the conventional vacuum method. A separate field investigation of the two techniques observed higher dust levels around the mist bolting machine.

Jan 1, 2008

By M. Dworzanowski

The beneficiation of fine iron ore will increase in importance in the future because most new iron ore resources will be in the form of lower grade ore deposits that will require liberation of iron ore minerals at finer sizes. Generally this fine iron ore will be beneficiated to produce a pelletizing concentrate with very strict chemical and physical specifications. In addition, because of the increasing demand for iron ore there are now more opportunities to produce by-product iron ore from mining operations producing other commodities. In the past the associated iron ore minerals would report to final tailings but now there is potential value to be realised from by-product revenue. These by-product iron ore opportunities are almost all centred on producing pelletizing concentrate. Currently pelletizing concentrates are produced mainly by various combinations of flotation and magnetic separation. The selection of the beneficiation route will depend on ore mineralogy and considerations around plant capacity and final concentrate quality. The main economic iron minerals are magnetic, haematite being paramagnetic and magnetite being ferromagnetic. This, therefore, means that magnetic separation can be applied, in principle, to all fine iron-ore beneficiation plants. While flotation has a considerable capacity advantage over magnetic separation, the real advantage of magnetic separation over flotation in fine iron-ore beneficiation is that treatment of -10 µm iron ore is possible-in flotation, the feed is deslimed at 10 µm and the -10 µm stream is considered to be final tailings, even though there is often a significant amount of contained iron ore. This paper describes a study around the recovery of fine magnetite in the form of a pelletizing concentrate. The study is based on an evaluation of an iron ore by-product opportunity from an iron oxide copper-gold (IOCG) deposit. Experiments were conducted to quantify the differences in magnetic separation performance with decrease in particle size treated. A mineralogical evaluation of all the test work products was undertaken to facilitate the interpretation of the test work results. These results were then used to propose an economically viable flowsheet for maximizing fine magnetite recovery using magnetic separation.

Jan 1, 2012

The Santa Rita mine is located in north eastern part of Bahia in Brazil and is owned and operated by Mirabela Mineração do Brasil Ltda. Typical SABC circuit was designed as the preferred option for the 4.0 mtpa (500tph) to produce a P80 of 125um for flotation. Although the SAG was originally designed to operate with conventional radial pulp lifters, later it was fitted with Outotec?s Turbo Pulp Lifters ? TPL (Latchireddi, 2005). The milling circuit commenced commissioning on the 24th of October 2009 and the milling circuit achieved the nameplate capacity within days. with small and relatively simple measures to rectify. Since commissioning, the SAG mill has been working in fully autogenous grinding (FAG) mode with no balls (in contrast to the estimated 10% ball charge) and has been consistently treated up to 650tph. This paper examines the comminution design process, the operating philosophies, start-up experiences, post commissioning optimization and future development works. An evaluation of mill performance relative to the design criteria for the project life to date is also included.

Jan 1, 2012

By E. Henry, C. Mayer, H. Rott

Hangingwall deformation monitoring at Kiruna mine is a major concern for Luossavaara- Kiirunavaara AB (LKAB) since underground production is deepening toward the town of Kiruna. In the quest for more effective monitoring techniques, LKAB decided to evaluate the ability of satellite-borne synthetic aperture radar (SAR) interferometry to monitor ground subsidence by generating continuous deformation maps from satellite radar images. While adopted by other geoscience-related industries, SAR interferometry is still relatively untested in the mining industry. This paper describes the basic principles of SAR interferometry and describes how subsidence is monitored at Kiruna mine. The encouraging results are discussed as well as the benefits (continuous deformation mapping, low cost, fast, etc.) and limitations (sensitivity to snow and vegetation cover) of the technique.

Jan 1, 2004

By R. L. Castro

The extraction of ore in panel caving operations also involves the coextraction of non-economic material, known as dilution. Forecasting, avoiding, and understanding the mechanics of dilution is critical to longterm planning. The models of dilution that are currently in use in panel caving operations are those by Laubscher (1994), who postulated that dilution is due to gravitational flow and depends on the height of interaction, the column height, and the draw uniformity. This paper presents a back-analysis of extraction and dilution behaviour at Codelco?s El Salvador and Andina Divisions, which use panel caving as a mining method. This analysis was conducted in order to review the existent dilution entry mechanisms and calculation methods. Three sources of dilution were identified. The first source is ?gravitational dilution?, which is due to gravitational flow and mixing as dilution migrates by gravity from a sector located above the panel under analysis. The second source of dilution is ?caving dilution?, which occurs when an air gap is formed in a large area and a sudden propagation of a hang-up occurs, inducing early ingress of waste into the production level from a level above. The third mode observed is ?lateral dilution?, which occurs when the panel is located next to an exhausted sector and the broken material enters the draw column early during draw. In the last two cases, dilution could migrate large distances horizontally. The mine data indicated that draw and caving strategy are key for long-term planning of large panel caves.

Jan 1, 2014

By J. A. Bartol

A survey was made of accident data and operating practices related to overloading and uneven load distribution on haulage trucks in noncoal open pit mines. Safety and economic aspects were analyzed. A bibliography of the literature was prepared. Review was made of available or projected systems for weighing or load indicating that might be applied to haulage trucks. A model specification was prepared for an overload detection system. Several promising systems for overload detection were identified. One was installed and tested briefly in a 170-ton rear dump truck in a copper surface mine.

Jan 1, 1982

By B. C. Lewis

Have technological advancements in underground coal mining driven people's skills to new highs or have the expanded skills of mining people driven the industry's technological advancements. Who knows? What we do know is that both our technology and our people have made meaningful and significant advancements. Overall, longwall systems continue to increase productivity and retreat faster. Globally, gate road development is the primary bottleneck in a longwall mine. The primary bottleneck in gate road development is roofbolting. Generally, roofbolting is the bottleneck in room and pillar operations as well. This paper will present an integrated manufacturer's (Joy Mining Machinery) vision of the future in comparison to current equipment performance. Particular emphasis will be placed on roofbolter technologies.

Jan 1, 1999

The history of soft and hard rock underground mining is blemished with regional instabilities of mine workings. Whilst the potential consequences of regional instability events are recognised to be high, there is a false perception that the probability of them occurring is very low. In fact, Australia has averaged more than one event per year for the past 20 years. At least five fatalities and over $100 million of losses have been associated with the events. As such, they are a core risk to underground mining and have a significant effect on the quadruple bottom line of business û safety, environment, community acceptance and economics. This paper explores the important roles that risk management has in reducing the probability and consequences of regional instabilities. It concludes that education and continuing professional development are essential elements for effectively managing the risk.

Jan 1, 2003

This paper contains an account of some creep tests on electrolytic lead and some of its alloys. The stresses used in determining creep were 500, 350, and 200 lb. per sq.' in. The alloys contained silver, bismuth, tellurium, antimony and zinc respectively. All were castin vacuo, and tested "as rolled." Tests were done also on electrolytic lead which had been cast in air.The electrolytic lead contained 0.0005% total impurities.The preparation and vacuum casting of this lead have been described in a previous paper in this series. The preparation of the alloys, and the air casting of the electrolytic lead, are described in the next section.EXPERIMENTAL PROCEDURE.Every effort was made to keep the vacuum-cast specimens from contact with the atmosphere throughout their history.The ingots were stored eIther in a vacuum desiccator or immersed in heavy oil. The creep specimens were coated with vaseline except during rolling, etching and photography, which involved exposure to the atmosphere for about 45 minutes all told.It is not claimed that vaseline is a perfect shield against the intrusion of atmospheric gases. Possibly during the months that some tests were in progress the gases diffused through the vaseline and gained a limited access to the lead.Nevertheless, the use of vaseline gave protection that brought the tests nearer the ideal at which the author aimed, *Research Fellow, Dept. of Metallurgy, University of Melbourne.

Jan 1, 1936

By Camier R. J, Perry G. J

Extensive deposits of brown coal exist in the Gippsland Basin, primarily in the Latrobe Valley. The total quantities of economically winnable coal in this region of Victoria and in other smaller fields are large enough to adequately assure Victoria's future electricity needs and to also provide large quantities for alternative applications, including liquefaction. As a result of the recent conflict in the Middle East attention has again been focussed on the production of synthetic fuels from coal. There have been many investigations over the years into the production of oil from Victorian brown coal. The purpose of this paper is to summarise the scope, objectives and major findings of these studies, with the emphasis on the direct hydrogenation route for converting brown coal to oil. The principal alternative processes are carboniastion and hydrotreatment of the product tar, or gasification and Fischer Tropsch synthesis of liquids from the product gas. The attractions of Victorian brown coal which have encouraged these studies include: ò the vast reserves of Victorian brown coal and the favourable conditions for low cost mining, ò the high quality of the coal (low ash, sulphur and nitrogen contents), ò the high reactivity of the coal giving high yields of product in hydrogenation to liquid fuels, ò the extensive data base available on the resource and its characteristics, and ò the availability of a skilled workforce and extensive infrastructure in the Latrobe Region to support a major resource development project. These advantages have been partially offset by: ò the high moisture content of the brown coal and the cost of drying, and ò the priority previously given to electricity generation in the allocation of the brown coal resource.

Jan 1, 1992

By J. M. Simard, S. Morissette, P. Coursol, P. Mackey

A new, powerful model is presented that focuses on plant logistics and scheduling aspects of the smelting, converting, fire refining and casting operations at the Horne smelter. This plant complex is the largest custom copper smelter in North America. It handles a wide range of feeds and utilizes a number of proprietary continuous and batch technologies that require good scheduling in order to maximize plant capacity and efficiency. The present model was developed by Xstrata Process Support, in collaboration with the Horne smelter, and uses the Arena® software to evaluate the impact of a number of plant variables on the annual copper capacity of the plant. Model development was carried out by Xstrata Process Support, in collaboration with the Horne smelter, through the effective combination of process chemistry knowledge and detailed knowledge of the plant operation (including all material flows and transfers, as well as information such as operating on-line times, plant stoppages and also scheduled and unscheduled maintenance activities). A number of case studies were then examined, including the impact of anode furnace and casting cycle times on annual copper capacity and the impact of a one-crane mode of operation in the converter aisle, which normally operates with two cranes in service. The model predictions were found to match actual plant results very well. The present modelling of plant logistics and the scheduling aspects were found to add important dimensions at the plant with regard to projections of the real-life plant capacity. As demonstrated in the present case, this type of model and application can have a significant impact on optimizing operations at a given plant. This impact is particularly important in the current market environment, where emphasis is on maximizing plant output and lowering costs. These models can help yield the easily obtained gains that are clearly desirable in these times. Xstrata Process Support has developed Arena models for other operations and is available to explore new applications for a win-win situation at other plants, including mines and concentrator operations.

Jan 1, 2009

By R. D. Dukimo, M. V. Sevian

The nature of fracture and factors that control the extent of fracture in the tumble-drum and drop-tower tests have been identified. The product-size distribution, on which the standard strength indices for these tests are based, and the breakage rate constants depend on a number of factors other than the strength of the lumps. The standard indices and rate constants are meaningful only in a comparative context and for events whose loading mechanism is similar. The results of experiments on three Australian ores, from Yandi, Koolan and Mount Whaleback, are used in combination with fracture mechanics theory to explain why different tumble-drum standards have been found to be fully consistent. A more meaningful measure of strength could be the parameters of the Weibull function, scatter and average strength

Jun 19, 1905

The oxidation of sulphide minerals in aqueous suspension is discussed from several viewpoints. Limitations of our present knowledge are pointed out, and several points where further information would be of special interest are mentioned.Firstly, some properties of minerals and their effect on oxidation are discussed. Properties of different species, such as crystal structure, lattice bonding, and "metallic" properties are mentioned, and then the effect of variation within a given species is discussed. The effect of physical factors, especially particle size, is also considered. Other variables discussed include the importance of solution composition, and its effect on the nature and rate of reaction, and the use of various oxidising agents. Some factors concerned with the whole system, such as temperature, pulp density and stirring rate are then considered.Finally, the nature of various oxidation products is discussed with reference to the kinetics of reaction and the nature of the rate limiting step. It is suggested that more attention should be paid to electrochemical explanations of the reaction mechanism.INTRODUCTIONKnowledge of the factors governing the rate of oxidation of sulphide minerals in aqueous suspension is a prerequisite for the effective control of many ore treatment operations. Rapid oxidation of sulphides is usually desired during the leaching of sulphide ores and concentrates, but in the cyanidation of gold ores, or in the leaching of uranium ores, any oxidation of sulphides may be regarded as an undesirable side reaction. Knowledge of many of the factors involved is also of interest in connection with the oxidation of sulphides in flotation circuits and in natural ore forming processes.Systems for which some reasonably quantitative data have been published are listed in Table 1. Qualitative...

Jan 1, 1961

By Günter Huber, Bruno Mattle, Helmut Westermayr, Daniel Spöndlin, Max John, Nejad Ayaydin

PROJECT DESCRIPTION Alignment The Strenger Tunnel forms part of the S16 four-lane expressway between Landeckand Bludenz. The construction of this important East-West connection started in 1973with the Arlberg Road Tunnel as its key constituent. Beginning in 1992, solutions for the section between Pians and Flirsch were investigated. Efforts to conserve nature and to avoid potential avalanche and landslide areas led to a solution detouring the villages in the Stanz valley. The starting points were predetermind by the intersections at Pians in the East and at Flirsch in the West. As a result of the expected traffic load and the comparatively high gradient of 2.9%, both one-way, two-lane tubes were constructed at once. The north tube is 5.851 m long, the south tube 5.775 m, see Figure 1. Layout of Tunnel Cross-Section The tunnel cross-section was determined by 2 × 3.75 m wide, 4.70 m high roadways, two sidewalks and sufficient space for two fans above the clearance

Jan 1, 2005

By G. Kim

The influence of bacterial growth phase on the flotation behavior of malachite has been investigated in a well-controlled Hallimond tube system. The microflotation tests were conducted for malachite (45?53 µm) using different amounts (bulk phase concentration=1×108?5×109 cells/mL) of Rhodococcus opacus (R. opacus) as a collector, which was grown at mid-exponential versus stationary phase, at a constant speed (340 rpm), pH (6), and malachite-bacteria interaction and flotation time (each 10 min). Hug differences between R. opacus cells in mid-exponential and stationary phase was observed from the results for electrophoretic mobility and flotation tests. Specifically, the isoelectric point of the cells in the stationary phase was lower than that in the mid-exponential phase, suggesting that the amount and distribution of surface functional groups onto cell surfaces are likely different. Additionally, the cells in stationary phase led to significant increase in the flotability compared to those in mid-exponential phase over the background bacterial concentration level of 1×108?5×109 cells/mL. Furthermore, the flotation efficiency tended to increase with increasing cell dosage for stationary phase cells while no distinct difference was observed for mid-exponential cells.

Feb 27, 2013

By A. C. Fieldner

All technical facilities of the Bureau of Mines have been geared for more efficient use and conservation of mining equipment, developing plans for safety, improving the quality of coal through better methods of preparation, studying the problems of coal storage and utilization, and extending the uses of coal5/ for the war and postwar economy. The Bureau is now analyzing all of the coal purchased by the Army and much of that required by the Navy. Work on boiler feed water was doubled over last year to meet the increased demand made by the War Department for protecting vital boiler plants in many new camps and defense plants. Progress has been made in safely storing coal to reduce dangers of spontaneous ignition to a minimum and to preserve coking power. Mixtures of oil and coal to be used as a substitute fuel have been investigated. Technical service on the conversion of plants to other fuels has been given to government agencies and private consumers. The possibilities of making motor fuel,

Jan 1, 1944