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By P. Rosario

"Current industry practice for HPGR assessment and sizing relies on conducting a series of tests using pilot-scale machines with roll diameters of 700 mm to 1000 mm. Substantial amounts of sample are required for such pilot test programs, typically 1 to 10 tonnes of the sample is needed depending on the level of study and complexity of the resource. Collection of large quantities of representative samples during the early stage development is challenging and expensive, thus significantly hinders the HPGR technology from being incorporated into early-stage designs. A robust and reliable laboratory test is therefore needed to allow a fair consideration of HPGR for early stage projects. With support from the Canadian Mineral Industry Research Organization (CAMIRO), the NBK Institute of Mining Engineering at the University of British Columbia (UBC) developed a suite of Piston Press bench-scale tests that correlated to pilot and full scale HPGR operating information (Davaanyam, 2015; Davaanyam et al, 2015; McClintock, 2018). The Piston Press Tests (PPTs) are capable of assessing the HPGR technology at the scoping, pre-economic analysis (PEA), and pre-feasibility (PFS) stages of project development. This paper will briefly describe the theory on which the PPTs are based, and then presents a case study conducted for a copper deposit to show how the PPTs are being used for scoping and pre-feasibility level studies. Specifically, the PPTs are being used to provide information for preliminary sizing and selection of an HPGR and to assess the effect of ore variability on HPGR performance. The results are also applied to developing HPGR circuit designs and can be incorporated in simulation so that optimum design parameters can be selected.INTRODUCTION It is widely accepted that high pressure grinding rolls (HPGRs) offer a viable energy-efficient solution for the modern comminution flowsheet design. Table 1 summarizes selected examples of HPGR applications in the hard rock mining industry. The main benefits of HPGRs are energy savings which leads to lower operating costs, and its stable operating characteristics that can better cope with variations in ore hardness when compared to the conventional SAG mill-based comminution circuits."

Jan 1, 2019

By N. Shi, T. G. Joseph

The design of dippers for cable shovels has essentially remained unchanged for the last 100 years. In the past 10 years, shovel manufacturers have started taking another look at dipper design, resulting in changes that have borne models from major manufacturers that address some of the wear conditions and material retention problems that dominate maintenance and operational costs. However, with the exception of added lateral curvatures to the front and corners of the dipper, the geometry is essentially unchanged. This paper looks at the criteria that have resulted in the first new cutting dipper design in a century. The design is based on kinematic considerations, reflected in a revolutionary geometry that matches the range of motions of the shovel, designed to minimize wear, impact loading and power required to dig, thus maximizing productivity for a minimum energy requirement. The shape configuration is such that the weight of the dipper is reduced through wall thickness, enabling a larger capacity dipper to be conceived for the same shovel. Benefits are reflected in reduced operational and maintenance costs and increased productivity.

Jan 1, 2006

By Oscar Lee, B. W. Gandrud, F. D. DeVaney

"IntroductionFlue dust which results from the smelting of ores containing appreciable quantities of fines is one of the troublesome products of iron blast-furnace practice. Gases issuing from the furnaces at a high velocity carry small particles of coke, ore and flux into dust-collecting chambers. These particles constitute the flue dust. Lasses of iron ore through the production of flue dust vary between wide limits in the different furnaces, and depend on a number of factors, such as size and design of furnace, amount of fines in the ore, the operating conditions and the blast pressure.Blast-furnace operators of the Birmingham district keenly realize this waste. The ores are comparatively low grade and require more fuel than is ordinarily used elsewhere. Hence the flue dust is low in iron content and high in coke. As a result it is not in suitable condition for direct sintering. In many other iron and steel centers direct sintering is a common practice. In the Birmingham district efforts have been made to prevent this loss by recharging the dust into the furnace, but, as might be expected, a material fine enough to be blown out once will very likely be carried over again.In general, the flue-dust losses in this district will average 250 pounds per ton of pig iron produced, but at times the losses at different furnaces are substantially higher or lower than this figure. On the basis of the present rate of pig-iron production, the annual loss of flue dust exceeds 300,000 tons. The iron content of the dust probably averages 25 per cent, therefore about 75,000 tons of iron is wasted yearly, or about 3 per cent of the iron mined is lost in flue dust."

Jul 1, 1926

By Thomas M. Gurtowski

This paper presents a summary of allowable bearing pressures and skin friction values that have been used to design drilled pier foundations for support of high-rise structures in downtown Seattle, Washington. These design parameters are based upon a review of geotechnical reports and records of more than 20 building projects. The following pages present a description of the soils encountered at these sites including foundation bearings soils, and design bearing and friction values. The accumulated data is summarized in Table 1, and the locations of the buildings are shown in Figure 1. A detailed description of the construction of two belled drilled piers are presented illustrating typical methods and procedures used in downtown Seattle. The two cases are from the Washington State Convention and Trade Center (WSC&TC). SEATTLE AREA SOILS The Puget Sound area was subjected to several major glaciations during the Pleistocene Epoch. Glacial ice originated in the cordilleran and coastal mountains and the Vancouver Range of British Columbia. The maximum southward advance of ice reached the area about halfway between Olympia and Centralia. As a result of these glaciations, the Puget Lowland was filled to significant depths by glacial and non-glacial sediments during the Pleistocene.

Jan 1, 1990

By Earl Rau

Introduction Will cogeneration be a major power source in the future? The location of electric power generating plants has changed. In 1900, more than 50% of electricity was generated by industrial plants. Since then, industrial plant generation of electricity greatly decreased to 17% in 1950 and to only 3% in 1980. Changing economics in electric power generating costs, though, may allow cogeneration to reverse this trend. Cogeneration has been defined as the simultaneous production of electric (mechanical) and thermal energy from a single energy source. Some applications are considered to be byproduct generation of electricity from industrial, thermal operations. Cogeneration is not new to the mining and minerals industry. Smelters and steel mills have used waste heat to generate electricity. Public Utilities Regulatory Policies Act of 1978 The potential for increased industrial cogeneration of electricity is related to the March 9, 1978 enactment of the Public Utility Regulatory Policies Act (PURPA). The US Supreme Court ruled that PURPA is constitutional. The court upheld requirements that utilities interconnect to cogenerators. It also ruled that 100% of avoided costs be used as the guideline for electricity sales by a qualifying facility (QF) to a utility. The state of New York established a floor price $0.06/kWh for electricity sales from a QF to a utility. It is obvious, then, that a cogenerator must first establish price and then become a qualifying facility in order to sell electricity to a utility. Proposed cogeneration plants The estimated industrial cogeneration potential for the years 1986 to 2000 is 9500 to 25,000 MW. Industries represented in this cogeneration estimate are pulp and paper, petroleum, chemicals, food, textiles, rubber, plastics, steel, lumber and wood, cement, glass, metal fabrication, and industrial parks. A cogeneration plant has been proposed for the Union Carbide chemical plant in Institute, WV. A steam turbine/generator would be installed to replace the pressure-reducing valve in the 2.7 MPa (400 psig) header. Scott Paper Co., Mobile, AL, proposed a cogeneration plant using a coal- and wood-fired boiler and a turbine/generator to produce process steam and electric power. A cogeneration system has been proposed for a large oil refining plant. A pulverized coal boiler would produce high-pressure steam to operate a turbine, generator. The exhaust steam from the turbine will go to the process and an existing turbine. Kansas City, MO's Armour meat-processing plant has proposed a cogeneration plant. This proposal is to use a natural gas or oil-fired, gas-driven turbine and a generator. The waste heat from the gas turbine would go to a heat recovery boiler for use as process heat. Dade County, FL is implementing a central energy system to supply electricity, air conditioning, and domestic hot water for five buildings in downtown Miami. The cogeneration system is to provide flexibility, to optimize fuel use efficiency while serving the variable thermal demands. Generation of electricity from municipal waste is not considered to be a cogeneration process but is covered by PURPA. Special considerations are provided for waste/electric power generation to encourage the development of these systems. ?

Jan 7, 1987

By M. F. van der Merwe

Anglogold Ashanti?s Kopanang Gold Plant (previously No. 9 Gold Plant) treats ore from Kopanang and Tau Lekoa shafts. The plant is twin streamed and has dedicated treatment circuits, from milling to final product, for each shaft. Waste rock material is used to compensate for the mill gap on both streams. Each stream consists of three 4.85 m x9.15 m ROM mills in closed circuit with a single stage hydrocyclone, milling an average of 7 000 t per day. The liner configuration in each mill consists of six rows of 30 grid liners along with rectangular lifter bars. The topic of gold lock-up is not new and has been investigated and reported on many times, both within Anglogold Ashanti and the broader mining industry. Although the lock-up mechanism is understood, its measurement is neither practical nor precise. The initial lock-up in a new liner and the release as the liner wears down cannot be accurately quantified. Previous test work carried out on Kopanang Gold Plant (with a ?gold scanner?) measured the natural gamma radiation emitted by uranium. This radiation is in proportion to the mass of concentrate locked up in the grid liner pockets, as well as between the cast-on backing plate and the shell. The ratio of concentrate lock-up was estimated as 35% behind the liners and65% in the pockets. Mill gravity concentrates are recovered during routine relining operations from behind the grid liners at Kopanang Gold Plant. Prior to relining, the liners tend to release the concentrate from the pockets as the liners wear. Historical Kopanang data from actual ?mill gold? smelted indicates that an average of 29 kg gold is recovered from behind each row. This indicates a total lock-up of 250kg gold per mill. This locked-up gold should preferably be minimizedor eliminated for the following reasons: ?The cyclic build-up and release of gold in mills complicates accounting ?Gold concentrate arising from liners is a security risk and creates a major mechanism for gold theft ?Loss of interest on the value of 250 kg fine gold is significant and was a major driver for the project. These factors led to the need to develop techniques to eliminate or at least minimize the gold lock-up in the mills. Wave liners, with rubber inserts, have been successful in eliminating lock-up, and were tested at Kopanang Gold Plant in November 2000. However, due to increased load-slip and high wear rates associated with these liners, this option proved less economical in terms of liner wear. Grid liners, with rubber-filled pockets, demonstrated a very high wear life and eliminated pocket lock-up. This system was successfully trialed in January 2003, but unfortunately did not prevent lock-up behind the liners. Current developments have resulted in a system that eliminates both pocket and backing plate lock-up. The conventional grid liner design has been modified to remove its steel backing plate. Rubber inserts that are integrated onto a rubber backing plate, have been designed to be used with the newly modified grid. The backing plate and grid pockets are now completely occupied by rubber, thus completely eliminating concentrate build-up around the new grid liner system installed in November 2003. Results to date are promising and liner life is expected to exceed conventional performance.

Jan 1, 2005

By Huang Zhiwei, Paul Skayman, Kevin Holley

In 1989 The First Brigade for Geology and Mineral Exploration of Qinghai Province discovered gold at Jinlonggou and Qinlongtan, Tanjianshan. Between 1992 and 2002 small scale mining was carried out at these sites using underground mining methods at Jinlonggou and an open pit at Qinlongtan. During 2003 and 2004 geotechnical investigations were carried out in support of a bankable feasibility study. An important objective of this investigation was to meet both internationally accepted standards and codes of practice, and also to satisfy the Chinese requirements. Extensive use of local experience was utilised. Where possible geological drilling information was incorporated into the assessment. Extensive geotechnical mapping of surface and underground exposures, and index testing to gain an appreciation of rock intact strength were used to characterise the sites. Rock mass classification (MRMR) was used to assess indicative overall slope angles and appropriate bench stack heights for the proposed pits at Jinlonggou and Qinlongtan. Measured discontinuity orientations were used in kinematic analysis to assess stability of possible pit slope geometry at a batter and overall scale to provide preliminary recommendations for the pit slope configuration. Numerical modelling was also carried out to improve the understanding of anticipated pit behaviour. Site investigation and preliminary geotechnical design details, that incorporate site specific conditions for the formation of open pits at Tanjianshan, are discussed in this paper.

Jan 1, 2006

By H. S. Venkatesh R. Balachander, G. C. Naveen

During the construction of a 1020 MW underground hydroelectric project in Bhutan a huge rock fall took place in the Downstream Surge Chamber (DSC) during March 2016. The total quantity of rock in the fall area is estimated to be about 1,50,000m3 (2.6 billion cubic feet), out of which about 25,000m3 (0.44 billion cubic feet) of muck was removed. The removal of muck was stopped apprehending that the cavity formed due to the rock fall may get further aggravated leading to widening and destabilising the adjacent transformer hall cavern or it might day light as the top cover was about 190m (623 feet). As the fall has virtually blocked the 314m (1030 feet) long cavern and divided it into two different chambers (south and north), and that the muck cannot be disturbed, it was decided to erect concrete wall on either side of the fall up to the cavern roof and then later address the filling of the cavity with appropriate fill material. As the access to the DSC was there for the southern side it was decided to extend a cable tunnel which was terminated at a distance on the north side of the cavern by D&B so that once it gets punctured into the north wall of the DSC it can be used to access the fall from this front too. This is a unique situation where in every blast approaching the DSC, the parting between them is diminishing and hence the tunnel blast will be exerting axial load on the parting wall leading to dynamic transient loading conditions and buckling may take place on the northern wall of DSC. This paper describes the various drill blast combinations adopted for successful excavation of this tunnel.

Jan 1, 2019

By B. M. England, M. V. Swain, N. Bristow, R. D. Dukino

The toughness and fracture mechanisms of ores with significantly different microstructures from Yandi, Koolan and Mount Whaleback were studied with a view to understanding their degradation behaviour. Bulk fracture toughness was determined by the 3-point single-edge notch beam test and the results interpreted using Weibull statistical analysis; indentation fracture mechanics was also used to measure fracture toughness of the different mineral forms and to understand their response to contact fracture

Apr 1, 1995

By C. S. Tout

While investigating methods for determining the best temperatures for hot-working experimental stainless steels, the Bureau of Mines Albany Metallurgy Research Center developed a machine in which hot-twist tests could be made in a few minutes. This machine is similar to some used previously except that specimens are heated by induction instead of by radiation, and their temperature is measured by a calibrated radiation-detection unit instead of by a thermocouple. In. developing the technique for using the new machine, tests were made on specimens of medium-carbon steel, mild steel, and AISI (American Iron and Steel Institute) type 304 stainless steel. Tests also were made on as-cast specimens and preworked specimens of experimental AISI type 202, low austenitic stainless steel, and as-cast specimens of AISI type 301 experimental stainless steel. The optimum hot-working temperatures were determined for all types of steel tested. Also, data were gathered on the effects of test speed and temperature on torsional strength and the effect of twisting on tensile stress in the specimen.

Jan 1, 1962

The papers contained herein summarize results of various recent Bureau of Mines investigations in the area of mine power distribution systems. They are based on information from Bureau personnel, contractors and grantees, and Mining Enforcement and Safety Administration. Conclusions drawn from a series of parameter measurements on mine power systems, taken over a 3-year span, are presented. Personnel and equipment hazards due to faults on isolated, solidly grounded, and resistance grounded three-phase systems are discussed. Two papers cover dc applications of circuit breakers, including a novel protection scheme for trolley lines. The methods of suppressing induced arcing currents and voltages in a-c machines are evaluated. An evaluation program for ground monitors is described. Acceptance test procedures and the importance of various paparameters for trailing cable splice are covered. A number of techniques for locating faults in trailing cables are described.

Jan 1, 1975

By I. H. Van Horn

IN the development of the incandescent electric lamp one aim of the investigators has been to establish the fundamentals of lamp design, so that the performance of any new lamp may be accurately predicted. The study of the temperature relations in lamps has done much toward establishing these fundamentals. Fig. 1 gives the typical FIG. 1.-ARRANGEMENT OF PARTS IN MAZDA B AND MAZDA C LAMPS. arrangement of the lamp parts in both the Mazda B (vacuum) and Mazda C (gas-filled) lamps. The outstanding differences are the filament form and the bulb shape. The ideal lamp is one in which the filament operates at a uniform temperature throughout its length. In practice, it is necessary to disturb this uniformity by the introduction of supports and terminals. The amount of cooling at the supports and terminals affects the over-all efficiency of the filament as a light producer. The life of the lamp is ordinarily proportional to the maximum and not to the average filament temperature. The Holborn-Kurlbaum type of optical pyrometer has

Jan 9, 1919

By F. H. McDowell

The increasing interest in the subject of electrical separation warrants the addition to what has already been written of a few lines covering the practical workings of the Tilly Foster mill under the direction of Mr. E. S. Moffat, General Manager. Since my last paper was presented to the Institute, Mr. S. P. Tomkins, the superintendent, has had thrust upon him for solution several problems complicated by the introduction of new conditions. 1. The richer portion of the lean ore dump, and that nearest the railroad track, having been worked up in 1890, the handling of the balance, including a largely increased amount of rock, could only be accomplished at an increased cost. 2. The tailings had accumulated close about the mill to such an extent that arrangements had to be perfected to move them further away.

Jan 1, 1893

By Parker A. J, Muir D. M

Solutions of acetonitrile in water dissolve water soluble copper(I) chloride. Removal of volatile acetonitrile from the resulting solutions, by distillation with low grade steam, precipitates pure copper(I) chloride. This is used to purify a crude copper chloride sublimate from the chlorination of nickel matte but is applicable to other sources of copper(I) chloride. The pure product can be converted to pure copper(I) oxide, copper(II) oxychloride or pure copper metal directly.

Jan 1, 1980

A mini- or micro-machine is a small electro- mechanical device. There are several existing applications of micro-sensors such as the accelerometers used in automobile airbags or the force sensors and grippers used at the ends of micro-surgery tools. Potential applications of existing mini- and micro-technologies are possible and could be used to improve the control and efficiency of fragmentation, heap leaching and other mining and mineral processing operations. A more radical proposition is to devise mass-produced, possibly disposable, minimachines that would operate in large groups. These would be the basis of highly selective, efficient, flexible, and clean mining and mineral processing methods. The paper is intended to promote discussion of how innovative applications of mini-technologies can be used to improve and radically change current mining and mineral processing methods.

Jan 1, 2002

Recently discovered Carboniferous bentonites are variable in charadeI and thickness, but being altered aeolian, ash-fall tuffs, they are probably extensive. Most are the Ca-montmorillonite type without the natural swelling characteristics of the Wyoming deposits, but their situation, thickness, and response to beneficiation through cation exchange may give them some potential as sources of future economic deposits.INTRODUCTIONLoughnan and See (1959) gave an account of bentonites and fuller's earth deposits of New South Wales. The most likely potential industrial sources were those occurring in the uppermost formations of the Newcastle and Singleton Coal Measures (Permian) in the Hunter Valley and deposited during epochs not marked by strong contemporary vulcanicity.One feature of the record of known occurrences at that time was the absence of bentonites from the thick volcanic sequences of the Carboniferous, but since this paper appeared, many bentonite beds have been discovered by the writer in the Carboniferous facies formerly known as the "Kuttung Series".The purpose of this contribution is to report briefly on the occurrence, genesis, mineralogy, and economic potential of these deposits which augment possible sources of bentonite near major industrial centres on the eastern seaboard.The potential world demand for bentonite would increase markedly with the trend to pelletization in the steel industry, if its use in this field became more general. More detailed mineralogical studies will be presented in later publications.STRATIGRAPHIC DISTRIBUTIONBentonite occurs at irregular intervals throughout a thick sequence of dominantly continental, plant bearing strata...

Jan 1, 1965

By H. M. Coggin

The study summarizes the state of the art in rock mechanics, open pit and underground mining, leaching, geology, metallurgy and financial analysis Conceptual design of pit slope caving technique and analyses explore concepts for the exploitation of ore grade remnants in the walls and bottoms of open pit mines and the potential economics of the adaptations Several coded sites were examined for future studies where the feasibility of the method may be demonstrated. An extensive bibliography has been developed

Jan 1, 1977

By B. B. Broms

Embankment piles are common in the Scandinavian countries (Kjellman, 1940) and in Southeast Asia as support of fills, light structures, bridge abutments and deep excavations (Eide, 1968) as described in the following. Untreated timber piles are often used for light structures and shallow fills when the ground water level is high since they are inexpensive and readily available. When the applied loads are relatively high precast concrete piles and steel piles are preferred. DESIGN CONSIDERATIONS Embankment piles carry the load from a fill or a struc-ture either through skin friction along the sides of the piles (Fig. 1a) or through a precast concrete slab or through pile caps at the top of the piles (Fig. 1b). When the load is carried by skin friction it is often economical to use small diameter timber piles because of the large surface area (Asplund, 1939). For precast concrete or steel piles concrete caps are used to transfer the load to the piles due to the relatively high capacity of the piles since the skin friction resistance alone is not sufficient to transfer the load to the piles.

Jan 1, 2010

By R. Armstrong, C. Ware, P. Sudan, G. Whitmore

The northern KwaZulu-Natal (KZN) coastal dune cordon, South Africa, extends from north of Durban into Mozambique. The Quaternary dune cordon, which can be up to 2 km wide, comprises a series of stacked, unconsolidated dunes that in places attain a height of over 100 m. Mining of the dunes produces much of the world’s supply of ilmenite, rutile and zircon. This paper documents the age of zircon grains separated from dune units, identifies likely source rocks and presents an evolutionary history for the dune cordon. Between 30 and 60 detrital zircon grains from three distinct units from the northern KZN coastal dunes were analysed for U/Pb isotopic ages using the SHRIMP II at the Australian National University. The samples represent units from the base (ca. 250 ka; luminescence age1),middle (ca. 190 ka2) and upper (ca. 20 ka2) portions of the coastal dune cordon. Zircon grain ages identify three source populations: (1) a 1 000 to 1 200 Ma group correlated to the Natal Metamorphic Province, (2) a 500 to 650 Ma group representing a Pan-African belt, which may correlate to the Mozambique Belt and (3) a ca. 650 to 800 Ma group of unknown provenance. Surprisingly, the presently exposed basement, comprising the Kaapvaal Craton and Archaean volcano-sedimentary sequences, has not supplied a significant amount of zircon grains (< 5%).This suggests that unroofing of basement rocks in the region has only occurred during the last 20ka. In addition, the absence of zircon grains younger than 500 Ma indicates that the bulk of zirconis not reworked from the Karoo Supergroup cover succession, but may be sourced by reworking of the Natal Group sandstones.

Jan 1, 2003

Impala Platinum?s No.16 Shaft mine is currently under construction and is expected to reach full production of 256 500 tons per month by 2014. Mining will start at 1 260 m below surface with a maximum mining depth of 1 535 m where virgin rock temperatures of 56.6°C will be experienced. As a result of depth, high virgin rock temperature and narrow reef mining, an expected total of 31.5 MW[R] of air cooling capacity will be required to achieve acceptable underground conditions. This will be achieved by cooling mine intake air in a single dedicated air cooling installation located on surface. The compact installation includes air cooling spray chamber, refrigeration machines, condenser cooling towers, evaporator and condenser water reticulation as well as all electrical and control systems. Construction and commissioning of the first phase of this air cooling installation has recently been completed on a turn-key contract basis.

Jan 1, 2009