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By T. N. Rushton

Rate minima are encountered in the reduction of magnetite with hydrogen. In a certain temperature zone, the reaction rate decreases with rise in temperature. This is inexplicable by classical kinetic theories; neither is a transition in reduction mechanism suitable for interpreting the observed behavior, This anomaly can be fully explained by hypothesizing two species of chemisorbed hydrogen with different adsorption coefficients and activation energies for adsorption. Competition between two energetic states of adsorption occurs with temperature rise, with the low energy state predominating below the anomalous temperature zone and the high energy state above it. The presence of two possible adsorption sites appears to be characteristic for oxidic adsorbents.

Jan 1, 1968

By G J. Corbett, P Magner, M McKenzie

Structures formed during ductile deformation have been reactivated during the later brittle mineralisation process. Two generations of folding are classified as: early recumbent megascopic FI folds and FI shears which transpose the hinge regions, and later upright F2 folds. S1 is folded about F2 folds which contain axial planar S2 crenulation cleavage. Vergence relationships between S1 and bedding indicate that many of the mineralised structures occupy sites of FI folds which have acted as plumbing systems for later gold mineralisation (eg Blackwater mine). The Globe-Progress gold mineralisation is localised by a major jog formed by sinistral strike-slip movement on two FI fault segments and mineralisation also occurs in smaller jogs along strike (eg Sir Francis Drake, Happy Valley-Merrijigs, Cumberland).   The lodes of ribbon quartz which exploit the FI shears and local bedding planes, are inferred to have mostly formed after the peak of metamorphism, possibly related to the emplacement of Carboniferous granites. This was followed by a sequence of vein deposition and wallrock alteration which consists of quartz-As/Fe sulphides ? carbonate - stibnite ¦ trace base metal sulphides and Bi-sulphosalts ? illitic clay/sericite-chlorite. Gold at Globe-Progress is mainly encapsulated in arsenopyrite. At Blackwater, free high fineness gold occurs in partings in lode quartz with late sericite-chlorite. The above sequence of events is comparable to that encountered in many intrusion-related gold systems throughout the Southwest Pacific region. There is a spatial relationship between gold mineralisation and dykes variably described as diabase, dolerite or lamprophyre. Alkaline rocks occur in many Pacific rim and older goldfields and may possibly be related to a magmatic source for gold mineralisation.

Jan 1, 1997

By R. J. Hickson

From 1993 through 1999 Cyprus Amax Minerals Company successfully completed eight major construction projects around the world. Six greenfield mines were brought into production, an ongoing operation was completely modernized, and an environmental issue was appropriately remediated. The projects stretched over three continents, from arctic Russia to the Atacama Desert, from 16,000feet to sea level, from city suburbs to remote wilderness, from a low of $130 million to over $1 billion. Open pit and underground; mill and leach; gold, copper, molybdenum, and coal were all encompassed. The breadth of diversity experience from these projects inspired Cyprus Amax to create a “best practices” project management protocol, to steer corporate expansion into the next millenium. This paper summarizes those best practices, while high-lighting project management pitfalls to avoid.

Jan 1, 2000

Atlas Copco Wagner launched its ST1010 Scooptram load haul dumper. The ST1010 replaces the company’s Wagner ST-1000 Scooptram. The improvements to the Wagner ST1010 include increased reliability, ease of maintenance and driver comfort or ergonomics. The ST1010 has been redesigned and has added several new features and options not offered in the earlier model. These include anew boom design with side stops. Heavy reinforcements to the bogie offer better protection against the harsh working conditions in underground mining and tunneling. An auto lube system has also been added as has paint-on grip tread to reduce slips and falls during maintenance checks or repair work. Other features include a heavy-duty, auxiliary-fan motor, an isolated transverter, remote diagnostic pressure taps, a bolt-on battery box, raised air-intake, improved fuel-filter access for easier maintenance, larger wear-bars around the engine tub, and smaller, higher output batteries

Jan 1, 2000

By J. R. Campbell

THE need for standardizing methods of arriving at definite conclusions regarding the cleanability of a given coal, and for measuring the performance of coal-cleaning equipment, is constantly increasing. Earlier notes by the author on this subject are amplified in this paper, because he believes that better preparation of bituminous coal is a partial solution of the coal operators' troubles. WASHABILITY STUDIES The term "washability" of coal was coined when washing was the universal method of separating coal from its impurities by utilizing their difference in specific gravity. This and analogous terms are still used in their broad sense although pneumatic or air separation is now used to clean coal. These terms are so used in this paper. Too much time or money, can hardly be spent on "feed surveys" to get a "picture" of the coal that is to be cleaned. There have been too many "rule of thumb" methods used. Screen analyses and "sink-and-float" tests on the raw coal enable the coal operator and washery man to predict within reasonable limits the results that may be expected from any efficient cleaning apparatus.

Jan 1, 1928

(This paper reviews the reasons for and the principles followed in designing and constructing complete new surface works at the mine of the Zinc Corporation Limited, Broken Hill, New South Wales, and describes the layout, plant, buildings and services.)The Zinc Corporation mine produces high grade lead, silver and zinc sulphide ore. Lead and zinc concentrates are sent by rail to Port Pirie, where the lead is smelted and the zinc concentrate is shipped to Tasmania, England and other overseas countries.Some time ago consideration was given to the advisability of sinking an additional shaft. For some years the old main shaft had been working at full capacity and developments underground had indicated that the mine would eventually be capable of an output greater than that which could be handled through the shaft. It was therefore decided to sink a new main shaft and the site chosen was in footwall country 900 feet south of the old main shaft. The reason for the move south was so that the new shaft would be opposite the centre of gravity of the ore-bodies at depth. The size of the new shaft is 27 ft. ,6 in. x 15 ft., and the work was put in hand early in 1936.It was intended to haul the whole mine output through this shaft, which was 1,600 feet from the mill then operating. An extensive conveyor system thus became necessary unless a new mill was built near the shaft. A careful study of the situation was made by the management and consideration was given to requirements for expansion, the condition of...

Jan 1, 1940

By John G. Henning

The Porcupine Joint Venture operates the Dome Mine in South Porcupine, Ontario. Dome underground began production in 1910. It is the longest continuous operating gold mine in Canada, producing in excess of 15 M ounces. More than 900 underground stopes have been mined and hundreds of miles of drifts, sublevels and raises developed. Underground mining methods included shrinkage, cut and fill and longhole. Not all stopes were backfilled upon completion, particularly the longhole stopes. The Dome open pit was designed above the underground mine workings such that, as the pit is excavated, it intersects underground drifts and stopes. Potential operational problems associated with the interactions between the stopes and the pit walls may occur, necessitating pit wall redesign, ground support installation and operational rescheduling. Each intersection of the pit with the underground mine workings is closely evaluated to maintain a safe working environment and wall stability. This paper discussed how risks to pit wall stability are assessed, mitigated and monitored.

May 1, 2004

By A. M. Tunstall, N. Djordjevic, H. A. Villalobos

The damage zone behind a typical smooth-wall blast in the open pit was assessed by visually examining diamond drill core to identify blast-induced cracking, mapping core rock quality designations to identify changes in fracture frequency and conducting uphole seismic testing to determine changes in rock mass characteristics. The results from the three techniques show reasonable correlation. They suggest that major damage, in the form of fracturing of intact rock, occurs at least 7 m behind the smooth-wall blast and significant damage, in the form of opening and extension of calcite-filled fractures, at least 12 m from the blast. At greater distances the dominant damage mechanism is the loosening of existent joints within the rock mass. In the trachytes at El Soldado these damage mechanisms correspond to peak particle velocities of 2 000, 900 and 500 mm/s respectively

Jun 19, 1905

By H. Razavizadeh

The recovery of copper from oxide ores containing from 2% to 4.1% acid-soluble copper from the Sarcheshmeh mine in Kerman province of Iran was investigated by agitation leaching in sulfuric acid media. Quartz, as a major constituent, and malachite, as the major copper mineral, were identified in the ore by X-ray diffraction (XRD) and microscopic studies. A series of leaching experiments on the ore was performed over a concentration range of 10 to 20 g/L and temperatures from 15° to 50°C for a maximum of 3 hours. An initial high dissolution of copper was followed by a very slow reaction. By increasing acid concentration and temperature, the dissolution rate of copper was accelerated. However, by increasing acid concentration, the acid consumption of ores was also increased. Surface morphology of solid residues at various leaching times was examined with a scanning electron microscope (SEM). All SEM micrographs of the partially reacted particles displayed a needle structure. The kinetic studies showed that the malachite dissolution rate could be modeled in two stages. About 85% of the malachite dissolution occurred in Stage 1, while the remaining 15% occurred in Stage 2. The data obtained for the leaching kinetics indicate that the dissolution for Stage 1 was a diffusion-controlled reaction with an activation energy of about 20.6 kJ/mole, and the dissolution for the Stag 2 was a chemical-controlled reaction with an activation energy of about 87.6 kJ/mole.

Jan 1, 2008

By Campbell Brown GA

IN 1904-5 diamond drilling operations in the Mount Morgan mine proved the presence of some inillioils of tons of rich, copper-gold ore, averaging about 45% to 50% silica and 22%Fe as sulphide. To smelt this ore in blast furnaces, without previous concentration, large quantities of basic flux.were required. Unlimited quantities of cheap, limestone, were available at Marmor, on the GladstoneRockhampton railway, 50 miles from Mount Morgan, but the supply of iron flux was a more difficult problem. Smelting operations started, with one' furnace in January, 1906, using as flux low-grade sulphide ore fro:m. the mine, containing very little silica. When the second, furnace was blown in this was supplemented by ironstone from, small aeposits in the immediate district. It was recognized that these sources of supply would be insufficient to keep the full plant going after the third furnace had been blown in. Accordingly, the deposits at Eabra and Mount Etna were opened, neither of which proved capable of supplying the quantity required viz, 1000 tons per week. Negotiations were meanwhile being conducted with the Marble Island Iron and Limestone Co. to obtain the right to mine at Iron Island, where a sufficiently large deposit was known to exist. Shipments from this source commenced in January, 1907, and ceased at the end of July of this year, when the metallic flux from...

Jan 1, 1912

By Abhiram Shankar

Construction projects are becoming more demanding both in terms of time and complexity. This necessitates intricate planning and sequencing of activities at the macro and micro level and continuous flow of resources across the project in order to achieve planned targets. Work and Resource planning need to be done in such a way that limited resources give optimal output. Currently dominant activity-based scheduling techniques like Critical Path Method (CPM) and Program Evaluation and Review Technique (PERT) do not model work-flow or resource-flow through a project life cycle. An extension to the conventional activity based planning is Location Based Management System (LBMS). LBMS has been explored and utilised in the case of repetitive and cyclic projects such as high rise buildings. This study focusses on the application of LBMS to repetitive and non-repetitive components of Power Transmission and Distribution (PT&D) projects involving construction of substation and cable laying. This paper presents the findings on comparing the current planning practice for cable laying with an LBMS based approach. A key finding of the study was that the conventional practice resulted in a schedule with several coordination issues that could not be identified in the planning reports. Using the LBMS based approach these issues could be identified and decisions required for resolving these could be made.

Aug 1, 2013

By C. M. Rule

Energy efficiency is currently a significant area of interest due to the Eskom power situation, which led to severe power impacts to the PGM, and indeed whole SA primary industries, in early 2008. Anglo Platinum has focused on energy efficiency for a number of years, especially in the concentrator operational area. New comminution technologies have been aggressively developed, which have shown real metallurgical efficiency gains as well as significant energy efficiency and saving potential for Anglo Platinum?s total electrical consumption as the company expands into a growing PGM demand market. This paper illustrates this programme?s activities, potential and considerable achievements to date.

Jan 1, 2009

By G. C. McLachlan

Two papers dealing with Noranda's milling operations have already been presented. The first1 of these covered the initial metallurgical problems connected with the treatment of the ore, while the second2 described the development of the mill from a 500-ton unit in 1928 to one with a daily capacity of 3000 tons less than six years later. At the time the second paper was written the equipment whirh had been installed to bring the mill capacity up to 3000 tons was being tuned into production and for this reason, though each step had previously been tested by a large-scale pilot operation, it was thought advisable to withhold metallurgical data until any starting-up difficulties had been overcome and anticipated requirements fulfilled. These requirements called for an improvement in gold recovery without any lowering of the previous ratio of concentration, and the pages that follow deal with the methods by which this result was obtained. An idea of the character of Noranda concentrating ore will be gained from an inspection of the following mineralogical analysis of the ore treated by the mill during 1933: MineRal Content Mineral ConteNt Chalcopyrite, per cent..... 6.8 Silica and silicates, per cent............ 18.3 Pyrite, per cent........... 22.1 Gold, native and as telluride, oz. per ton 0.15 Pyrrhotite, per cent....... 51.5 Silver, probably as argentite, oz. per tou 0.35 Magnetite, per cent....... 0.5 Thesr figures, which are typical, show that over 73 per cent of the ore treated consists of pyrite and pyrrhotite. Determirnation of the proportion of unrecovered gold associated with each of these minerals was therefore of primary importance in developing a suitable method for improving gold recovery. As pyrrhotite is magnetic, this information was obtained by making magnetic sorting tests on samples of the mill tailing and screening the material thus segregated. This showed that the magnebtic material finer

Jan 1, 1935

By R. J. Matetic, J. S. Peterson, P. G. Kovalchik

The National Institute for Occupational Safety and Health (NIOSH) has initiated a study of a roof bolter to reduce noise exposure to mine roof-bolter operators. An important segment of this research entails determining the affect of various drilling configurations on the performance (penetration rate) and sound power emissions when drilling into granite. Test conditions included using various combinations of rotational speeds and thrusts, using 2.54- and 3.49-mm- (1- and 1 3/8-in.-) diameter hexagonal and round drill steels, using vacuum and wet conditions and using drill media of differing compressive strengths. This paper details the affects of each of these variables on the performance and sound power level emission. When drilling into granite, it was found that wet drilling generated lower sound power levels and performed better than vacuum drilling.

By Thomas M. Gurtowski

The New Pacific Northwest Baseball Park, now known as Safeco Field, is located directly south of the Kingdome in Seattle, Washington, and will be the new home of the Seattle Mariners baseball team. The location of the ball field is shown on Figure 1, Vicinity Map. The seating capacity is 45,600, and outfield distances are 331 feet in left, 405 feet in center, and 326 feet in right field. The overall dimensions of the stadium are 680 by 800 feet. It is bordered on the east by the Burlington Northern Santa Fe Railroad main line. A unique aspect of this ballpark is the retractable roof with a north-south span length of 660 feet. The roof consists of three separate sections that roll on elevated rails running east-west on the north and south sides of the stadium. The soil conditions consisted of near-surface fill underlain with alluvial and Estuarine deposits to depths of 60 to 80 feet. The bearing soils consisted of very dense, glacially overridden deposits. Groundwater is 4 to 7 feet below the ground surface, and the alluvial deposits are subject to liquefaction during a strong motion earthquake.

Jan 1, 1998

By J. P. Morris

An experimental blast furnace in normal operation was quenched by substituting cold nitrogen for the hot blast air. More than 2,200 samples from the stack, bosh, and hearth were taken; 500 of these were selected for detailed analysis. Deductions are made as to the patterns of burden movement and gas flow; the reduction of iron oxides, including a comparison of ore and sinter; and the behavior of sulfur above the smelting zone. Metal and slag beads from the bosh were analyzed, as were samples from the hearth metal and slag. A brief description of a petrographic examination of the quenched burden is included.

Jan 1, 1963

By H. Foster Bain

THERE has never been a great civilized nation which did not have a mining industry; civilization cannot flourish without metal mining. Without tools we can have none of the 'industries that are the foundation of civilization and without metal mining we cannot produce the material of which tools are made. Therefore, if we have no metal mining we have no metals, no tools, no civilization. An example to illustrate this may be drawn from a recent article in the Saturday Evening Post which described the run-down condition of modern Athens. Athens is nothing but a busted mining camp! In its palmy days the Greeks so applied the leasing system to the silver mines of Laurium that the royalties, paid the expenses of government and instead of a tax bill the inhabitants received a pay check. The Persians came over to capture these mines but the Greek navy was built to defend them. When the silver mines played out, Greek civilization declined.. Our mining must continue if our civilization is to continue.

Jan 1, 1921

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 J Wei, A Yo, R Levy

Waste water reuse from municipal and industrial effluents is becoming increasingly important in many areas around the world. Water scarcity, local regulation and environmental impact are driving many industries like coal and copper mines to reuse the large volume of waste water they produce. For example, the Chinese coal industry generated about 4.2 billion tons of mine waste water in 2005 of which only approximately 30 per cent was reused. Coal energy represents 76.6 per cent of the total energy generated in China in 2007 and most of the coal-fired power plants are located in north-west of China, which is a water stressed area.The selection of mine waste water treatment process is challenging as the effluents typically contains high levels of organic compounds and salinity and their composition can vary significantly. In recent years there has been a growing interest in the integration of ultrafiltration (UF) and reverse osmosis (RO) membrane technologies for mine waste water treatment and reuse.In this paper, an overview of the design and performance of ultrafiltration and RO membranes applied for reuse of mine waste water are discussed. A study was carried out in two effluents treatment plants treating copper and coal mine waste water, which are located in Chile and China respectively. The following topics will be discussed to demonstrate the performance of an integrated membrane system in mine waste water reuse: The main challenges from copper mine waste water treatment: high level of chemical oxygen demand (COD); high level of total suspended solids (TSS); high salinity; high concentration of silica, sulfate, iron and other contaminants; and fluctuation of raw water quality. The main challenges from coal mine waste water treatment: high level of total dissolved solids, and waste water quality fluctuation. Design parameters for waste water treatment systems: Selection of pretreatment for dual-membrane system in the copper mine: Clarifier with coagulation and flocculation to remove high TSS; Dissolved Air Flotation (DAF) to remove non-settling solids; Media filtration to handle fine solids and particulate organics; Activated Carbon filters (ACF) to remove dissolved organics, colour and odours. Selection of UF and RO membranes and specific design of their recovery, flux, chemical dosage and cleaning regimes. Finally, the performance of UF and RO, including the main fouling factors and efficient cleaning procedures, will be presented and compared to the design parameters to demonstrate the efficiency and performance of the selected integrated membrane systems in each case.

Jan 1, 2009

By Scales PJ, Ralston J

Fine coal particles have been examined with respect to dustiness and its connection with various physical and chemical properties. It appears that a given coal will tend to be dusty ifthe moisture content is low and if the inert maceral content and overall rank are high. The hydrophobicity ofa coking coal (Young-Wallsend) and a steaming coal (Blair Athol) was examined in detail by a dynamic contact angle technique. The YoungWallsend coal had a higher contact angle, on average, than the Blair Athol sample. This result has important implications for dust suppression and associated processes.

Jan 1, 1986