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By Rob Thomas

Pre-driven recovery roads are used to speed up the longwall recovery process by reducing bolt-up requirements and by improving ground conditions on the face during the removal of the powered supports. To lower the geotechnical risks associated with the use of pre-driven recovery roads, and so improve its overall acceptance in the industry as a viable alternative to more conventional, potentially difficult and costly longwall recoveries, this paper outlines (i) a geomechanical model for the use and design of pre-driven recovery roads, (ii) an updated version of the worldwide database on pre-driven recovery roads, (iii) a summary of the various methods of holing a longwall into a pre-driven recovery road and (iv) a series of relevant ground support and strata management guidelines.

Jan 1, 2008

By D. M. Larsen

Since start-up in 1985, the Cannon Mine has produced and shipped a 170-g/ton (5 oz/ton) gold flotation concentrate to various smelters for gold and silver recovery. Several processes have been investigated to economically produce done' at the mine site from the refractory concentrate. This paper describes laboratory and pilot scale test work used in the process design and engineering. feasibility study of a 73-t/d (80 stpd) pressure oxidation and carbon-in-leach (CIL) facility. The designed pressure oxidation circuit utilizes a series of verti¬cal autoclave units operating at 170°C (338F) and 1.4 MPa (200 psig). Projected operating costs are discussed.

Jan 1, 1993

By Met B. E

The increasing pace of modern mining makes constantly greater demands upon the several contributing departments of rock breaking and transport, and rock-drilling, as the spearhead of attack, has received a great deal of attention with respect to both machines and steels. By a series of mechanical improvements, combined with the application of selected heat-treated alloy steels, the rock-drill has now been developed into a machine capable of rapid drilling and long service under severe working conditions. As a factoryproduct made under strict metallurgical control it is as foolproof as, say, the modern automobile, and, like its prototype, it can be kept in efficient operation by a minor amount of attention during use and by periodical adjustments and replacements.The same cannot be said, unfortunately, of the drills with which the machine is supplied; in conventional mine-shop practice these are made of the best tool steel shaped and heat-treated under the poorest of metallurgical conditions.The crudities of steel-shop practice have, in fact, always prevented the full exploitation of the steels available at any time, and even at the present day the general standard of treatment offers a contrast with the quality of the steels which moves the metallurgist to amusement, despondency or outrage, according to his temperament. Nevertheless, the tendency persists to meet the increasing demands of the rock-drill primarily by the use of still better steels, and secondarily by improvement, of the steel-shop practice. Athird type of development is the introduction of factorymade tools in the form of detachable bits and rods. It is proposed in this paper to deal with these three aspects of the recent developments in rock-drilling.*Re-written from a lecturette given during the First Ordinary Meeting, 1936.

Jan 1, 1936

By D. E. Sherwood

Recent developments in high torque hydraulic rotary rigs has lead to the construction of secant bored pile walls by rotary drilling methods in circumstances where earlier methods were difficult and in some cases impossible. The evolution of secant bored pile wall construction is described including classical, rotary drilled and continuous flight auger construction methods. The paper then details the restraints which have been created in recent inner city redevelopment, many of which were not relevant in the early days of the technique. Typical examples of walls are presented to show the adapatability and advantages of the secant bored pile wall method. A number of in-situ retaining wall construction techniques are then compared in detail with regard to relative cost, technical quality and practicality.

Jan 1, 1989

By Levent Ozdemir, Bjorn Nilsen

For several recent TBM tunnel projects, unexpected ground conditions have been encountered, causing extra cost, considerable delay, and in some cases major claims. Undoubtedly, insufficient and/or irrelevant site investigation and testing are among the main causes of such incidents. The purpose of this paper is to review the main investigations and tests relevant for hard rock TBM projects, with particular emphasis on the considerable development that has taken place over the last few years. Also, guidelines for defining optimum scope and extent of site investigations and testing are discussed, as well as the importance of adjusting the investigations and tests according to complexity of the ground conditions and project type.

Jan 1, 1999

By K C. Williams, A W. Roberts, J D. Prigge

For stockpile design, the flowability and structural interfaces are critically dependant on the stress conditions throughout the pile. Historically, the predictive methodologies for stress determination have been too conservative, which adds inefficiency to the stockpile reclaim interface selections, especially for live reclaim stockpile systems. In addition, accurate pressure profiling throughout stockpile is essential to correctly design the stockpile support structures, which are buried within the stockpile. Such buried structures include trestle legs or columns to support load-out conveyors or the roof of bulk storage sheds. Improved methodologies with respect to the development of the hoop stress condition which exists in material ædrawn-downÆ within the stockpile has been developed. This hoop stress approach has significantly improved the live capacity prediction to over 90 per cent accuracy and improved rathole structure prediction within live reclaim stockpiles. Additionally the methodologies in estimating the vertical and circumferential stress variation acting on buried stockpile structures have been significantly progressed, with experimental testing shown good agreement with the theory.CITATION:Williams, K C, Roberts, A W and Prigge, J D, 2013. Recent developments in stress analysis and live reclaim prediction within iron ore stockpiles, in Proceedings Iron Ore 2013 , pp 501-510 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By P. K. Hofmeyr

Base Metal (Cu, Ni, Mo, Zn, Co etc.) analysis traditionally has been very slow in conventional analytical laboratories which can lead to additional costs being incurred in waiting time of drill rigs or mining excessively off-reef. Recent developments in the automation of analytical laboratories now allow for very rapid turn-around times for base metal analytical data which can help reduce such costs as well as reduce the unit costs of the analyses themselves. 2.0 CONVENTIONAL ANALYTICAL LABORATORY PRACTICE Conventional analytical laboratories are necessarily are very manual. Sample preparation is slow and laborious, samples are moved from stage to stage manually and, typically, all samples are processed in batches so a sample which is the first to be, say, milled has to wait for the complete milling of the batch before it advances to the next stage eg. mixed with wax prior to pelletising for XRF analysis. Inevitably this results in long sample data turn-around times for laboratories handling large numbers of samples. Manual sample preparation can only be accelerated by increasing staff which increases costs and can lead to additional errors being introduced. Cleaning of sample preparation equipment, eg. crushers and mills, between samples is essential to avoid cross-contamination between samples and this is slow and labour-intensive. In manual sample preparation the correct sample numbers staying with the samples is totally dependent on the efficiency of laboratory operators. It is extremely difficult to detect when errors have occurred due to the switching of sample numbers during the sample preparation stages. Running duplicates and QC samples at best is only partially successful in detecting when sample number switching errors have occurred. Errors of this nature and cross-contamination problems due to incomplete cleaning of sample preparation equipment tend to occur when laboratories are working at pressure due to high sample numbers and when supervisors are not present during 24/7 laboratory operations which is often required on plant process control laboratories. These problems are common to all conventional analytical laboratories and their magnitude is dependent on the level of control and efficiency of QC systems practised by individual laboratories. The disadvantages of conventional manual analytical laboratories can be summarized as follows:- 1. Labour-intensive which is costly especially when multiple shifts have to be used during 24/7 operations.

Jan 1, 2005

By E. P. Deliac

The aim of this joint work between the French Coal Board and the Paris School of Mines is to be able to practically model the behaviour of a transverse drum cutting rock with picks. First a theoretical approach leads to the concept of cutting curves, giving forces and torque against penetration per drum revolution. Then experimental evidence, from full scale and reduced scale testing, validated and confirmed the theoretical shape of the curves. Finally practical applications are given, to improve the design or use of a shearer (or continuous miner). A micro-computer program is being developed to predict the cutting performances of a machine in certain conditions.

Jan 1, 1985

By Sanford Belden

My topic, Recent Developments in the Design of Electric Mine Locomotives and Mining Machinery, does not require me to go into a general review of electricity as applied to the mining industry. Interesting as that subject always is, what I might say in regard to it, by way of introduction, would be unnecessary use of your time, since such facts are familiar to all. First, we will consider the recent development of the electric mine locomotive. We may well pause for a moment to reflect upon its importance to the coal-mining industry of to-day. With the dawn of the electrical age its advent was inevitable. Our practical interest is aroused not so much by the first crude effort as by the great efficiency attained during the 30 or more years since the electric locomotive made its first appearance. To judge accurately what it means to coal mining, and through coal mining to the industrial field at large, we would have to know how many of these locomotives are in use throughout the country and their aggregate daily performance, and then compare the results with what could be expected with other forms of power. Such data are lacking, but it requires no statistician to make it evident that the electric mining machine is a tremendous factor in modern progress, and that without it the work of the world could never have reached its present magnitude. Not only has the electric mine locomotive served its own special branch of usefulness, but incidentally it has solved in the main the whole problem of electric transportation. It is but a step from the triumph of a 25-ton locomotive leading a long train of loaded coal cars from a mine to the electrification of common carriers. We may or may not be near any great change in this respect. Economical reasons may hold it back for an indefinite period. But the fact remains that in the development of our mine locomotives we have met this larger emergency, in mechanical type and efficiency, whenever it may come.

Jan 6, 1914

By Brian P. Waagner

Construction law in general and the law of deep foundations in particular continues to develop rapidly, particularly in the areas of risk allocation. Public and private owners are increasingly using contractual disclaimers to shift the risk of differing site conditions to contractors, and courts are increasingly willing to enforce these contractual devices. Perhaps also in an effort to control costs, public and private owners are turning to design-build contracting techniques. While design-build offers many advantages over traditional project delivery systems, it does not answer all of the risk-allocation questions that frequently arise. Even in design-build, problems with unanticipated subsurface conditions and defective design are not easily addressed. Finally, developments in electronic commerce present the potential to transform the construction industry.

Jan 1, 2002

By J. C. Farge, G. G. Jacox

"The effect of composition and process variables on the properties of Marmet and modified Ni-Hard slugs will be discussed. The effect of shape on the over-all performance of grinding media and its relationship to the end product has been investigated and these results will be reviewed. The cost effectiveness of slugs versus balls has been well documented under various operating conditions and this will be presented in detail. IntroductionThe selection of grinding media is based on the cost-to-wear ratio combined with the consideration that it must stand repeated impacts without breaking. The specific consumption of grinding balls and slugs depend s primarily on their microstructure, which, in turn, is controlled by chemical composition and by the processing condition s to which they are subjected during manufacture.The first part of the paper deals with the optimization of alloy content to produce cast iron slugs with microstructures consisting essentially of marten site and carbide and with hardnesses of 650 B.H.N. and higher. The second part deals with the use of cast iron slugs to replace forged steel balls in milling operations. Tests indicate that the shape of the media has little if any effect on results and that the hardness and microstructure of grinding media will determine its relative performance. Where price is equal under similar milling conditions, the cost effectiveness of cast iron slugs is superior to that of forged steel balls.In order to understand the role of alloying elements in cast irons, it is judicious to consider the microstructural changes which occur during solidification and subsequent cooling, particularly from above the eutectoid temperature. Solidification starts with the formation and growth of dendrites of austenite. As temperature decreases, an eutectic nucleates and grows between the primary austenite dendrites. Immediately after solidification, the structure consists of proeutectic austenite and of the eutectic of primary carbides and austenite. On cooling to room temperature, austenite can be retained or transformed to pearlite, bainite, martensite or mixtures thereof. It is necessary to prevent decomposition of austenite into pearlite by adjusting the alloy content. For best abrasion resistance, the microstructure at room temperature should consist essentially of martensite and carbide. These types of irons are known as ""martensitic irons "". Depending on the carbon content of the austenite and cooling rate, "" as-cast"" martensitic irons will contain different proportions of martensite and retained austenite. The more carbon in solution in the austenite, the lower is the temperature at which the martensitic transfoemation takes place. By the time room temperature is reached ., the transformation is seldom complete, and the end product is generally a mixture of martensite and retained austenite."

Jan 1, 1980

By Martin Herrenknecht, Karin Bäppler

The last five years have seen a remarkable increase in tunnelling projects in both soft ground and hard rock applications. Part of the increase is a result of recent Research & Development efforts to improve Tunnel Boring Machine (TBM) adaptability, capability and reliability. This paper will review the latest innovations in the TBM industry and explain in detail the results of these innovations followed by a forecast where the technology will take the tunnelling industry in the future.

Jan 1, 2005

By Paul Tyler

STRATEGICALLY situated in almost the heart of the leading fertilizer-consuming area of the United States, Tennessee long has ranked second only to Florida as a phosphate-producing state. Since 1932 its share of the national output of phosphate rock has increased steadily, and in 1937 its production mounted to an all-time record. More significant even than the increase in tonnage are the forward strides in technology. The Tennessee Valley Authority's research program has led to quasicommer-cial operations using hydroelectric power to manufacture concentrated phosphatic fertilizer that is used to further the farmer education program designed to streamline the fertilizer business and halt the appalling waste of farm land by soil erosion. Even more stimulating to chemically minded imaginations is the production of elemental phosphorus by a private company that not only has succeeded in extracting it from the phosphate rock in electric furnaces but actually has contrived to capture it and to transport it safely in tank cars. New values have been created for low-grade phosphate deposits, and the economic life of reserves has been lengthened while the waste of former years goes back into the mills for recovery of its values by modernized methods. Tennesse's phosphate-mining industry dates from the discovery of blue rock in Lewis County in December 1893. Its known reserves are of the order of 101,500,000 tons, which compares with the production of 825,099 tons in 1937; that is, 21 per cent of the phosphate-rock output of the whole nation. The total output reported from 1894 until July 1, 1938, was approximately 19,000,000 tons. Official estimates of reserves are overly conservative and evidence submitted before a joint Con-gressional committee in November 1938 places "probable" reserves at more than 6,000,000,000 tons.

Jan 1, 1939

Currently an Australian Standard for tunnel fire safety is being developed for road and rail tunnels. Other local guidance relating to tunnel fire safety that has recently become available includes publications by both the Roads and Traffic Authority and RailCorp of New South Wales. Internationally, the World Road Congress has completed its 2004 - 2007 cycle, which has resulted in a number of publications. International developments in rail guidance include a new European Standard regarding fire safety in railway tunnels that will come into effect in July 2008. In addition, the National Fire Protection Association committee NFPA 130 are in the process of revising their standard for fixed guideway transit and passenger rail systems, which is due for publication in late 2009. This paper outlines the status of these and other recently published relevant local and international fire safety guidelines and their implications for tunnel projects in Australia.

Jan 1, 2008

By J W. Hedenquist

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Epithermal deposits (Au or Ag dominant, ± base metals) form within ~1 km of the surface in volcanic belts, both arcs and rifts, with the different tectonic settings reflected in distinctly different characteristics. Within arcs, deposits are typically intrusion centred and commonly associated with hypogene advanced argillic alteration, both in lithocaps and as halos to shallow or proximal portions of some veins; such alteration is coupled with processes that form porphyry Cu-Au deposits at depths of ~1–3 km. Introduction of metals is related to the subsequent phyllic-stage overprint; if this fluid rises to the level of the lithocap or into epithermal veins, Au mineralisation with Cu or Ag may occur, associated with sulfate minerals or muscovite. By contrast, Au-rich (both low Ag:Au ratio and bonanza grade) colloform quartz veins form at shallow depths in volcanic rifts, typically within a few hundred metres of the surface, with clay halos and topped by silica sinter if the palaeosurface is preserved. The geologic variability in volcanic belts, including host rocks, structures and hydraulic gradients, means that many epithermal deposits vary from the end-member features of the principal styles. Effective exploration requires familiarity with end-member styles as well as potential variations, plus the mineralogical indicators of palaeotemperature (eg evidence for erosion depth, fluid flow channels). This knowledge helps the geologist in the field to imagine what might be buried and where, and how to best test the target with drilling.CITATION:Hedenquist, J W, 2015. Recent developments in understanding of and exploration for epithermal deposits in volcanic arcs , in Proceedings PACRIM 2015 Congress, pp 11–16 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Harvey T. Gracely, Mark J. Woodhull

DURING the past few years a marked refinement has taken place in the design of electric power shovels for the mining industry, increasing their digging ability and speed of operation without adding to their total weight. The increase in pay load has been accomplished by a more rigid engineering analysis of shovel design, involving the adoption of new special alloy steels, new sections, and new welding methods. Emphasis has been placed on lightness with increased strength, which is most clearly shown in the front-end equipment where dipper, handle and boom are new in design, material, and construction.

Jan 1, 1938

By Alain Blouin, Mohamad Sabsabi, Aissa Harhira, Paul Bouchard, Greg Lithgow

"The objective of this study was to demonstrate the application of Laser-Induced Breakdown Spectroscopy (LIBS) to the continuous analysis of online monitoring of Al, Mg, Ni, Mn, Si and Fe in nickel ore limonite and saprolite slurry samples. Analysis was performed on slurry samples in air at atmospheric pressure. Two pure samples of limonite and saprolite were used. Mixtures of the two samples in varying proportions were used to build calibration curves, study the influence of solid/liquid ratio, and evaluate short and long term reproducibility. The LIBS measurement of these elements is independent of the water content (from 70-85%, the range allowed by our setup). Repeatability of the measurement and long term reproducibility (from day-to-day) were below 1.2 % and 2% respectively for all the elements studied in our conditions. The results obtained showed that an industrial LIBS analyzer could provide the chemical composition of the six elements Al, Mg, Ni, Mn, Si and Fe within 1-2 minutes.IntroductionThe metal-producing industry faces the major challenge of increasing productivity, reducing costs, and maximizing benefits from existing equipment. By pyrometallurgy, metal making involves the basic steps of charging the furnace, melting the charge and refining. By hydrometallurgy, the metal refining is carried out through the dissolution of the metal by chemical reaction and electrolysis. During refining either by pyrometallurgy or hydrometallurgy, it is critical that operating parameters be adjusted and controlled so that the chemistry of the melt or the solution is within predetermined limits. Presently, the complete turnaround time for sampling, sample transfer, analysis and communication of the results to the operators is often 30 minutes or more."

Jan 1, 2016

By Magnus Ek

After the installation of three new converters as part of the recent expansion of the Rönnskär smelter completed in 2000 work continues to further improve the converter operation. The converter upgrade led to an increase in blister copper taps from 150 tons per batch to more than 300 tons. The total cathode copper production increased from 130,000 tons in 1999 to 230,000 tons in 2001, the first year in full production. In recent years focus has been to improve operating practise, maximize the blowing time, extend the converter campaigns hence to reduce the specific brick consumption and improve the converter slag composition.

Jan 1, 2005

By D. Pickering, R. Wharton

The deadline for meeting legal requirements relating to the sale of explosives in the European Union was 1 January 2003. The paper examines the range of materials that have already been certified by the different Explosives Notified Bodies as well as recent national and European Commission decisions relating to this work. The implications of enlargement of the European Union are also discussed as is the future role of the Great Britain Explosives Notified Body in certification and assessment.

Jan 1, 2003

By R. K. Wharton

The paper reviews the development of European harmonised standards for fireworks, recent major incidents involving the bulk storage of fireworks which led to research funded by the European Commission, progress with the forthcoming European Regulation on pyrotechnics and potential issues relating to the certification of products within the scope of the new Regulation.

Jan 1, 2005