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By S. Jayasekera, A. M. T. S. Bandara, J. Kyle, E. Koenigsberger, L. Koenigsberger

The extraction of rare earth oxides from fluoroapatite rich phosphate concentrates often involves a weak acid leach of fluoroapatite and a sulphuric acid bake of the leach residue followed by water leach and precipitation to obtain an intermediate product. The main aim of this study was to determine and rationalize the solubility of rare earth metal ions in synthetic solutions representing various process liquors at the temperatures 40, 60 and 80oC. The liquors contained different acid and metal ion concentrations with respect to sulphuric acid, phosphoric acid and sulphate salts of sodium, magnesium, aluminium, potassium, calcium and iron(III). A solid of mixed rare earth carbonates was used as the source of rare earth metal ions. The solubility tests and characterization of solids using XRD were conducted at Murdoch University laboratories as part of the process development for the Arafura Resources Nolans rare earth project. The composition of initial carbonate solids and the solids and solutions formed after saturation were analysed for rare earth and other elements at TSW Analytical Laboratories in Perth using ICP-MS and ICP-OES. The precipitated solid in sodium-rich acidic sulphate solutions is the double salt NaRE(SO4)2 based on the solid assays. However, in acidic solutions free of sodium or of low concentrations of sodium the precipitated solid appears to be RE2(SO4)3.

Jan 1, 2014

By J. Wong, M. G. Lipsett, L. K. Daneshmend

"Current trends of increased size, complexity, and automation of surface mining equipment necessitate more comprehensive and objective techniques for equipment comparison and selection. The field of reliability analysis provides tools to generate quantitative bases for maintenance and reliability aspects of such comparisons. Results from statistical analyses of failure and repair time data are used to perform the comparison. A case study is presented which analyzes five machines of two different technologies and three different designs.IntroductionThe surface mining industry is currently faced with a rapid evolution in production equipment. The more obvious trend in this evolution is the steady introduction of even larger machines. Parallel, and complementary, to this increase in size is the introduction or adaptation of new technologies. Together, these two trends result in new surface mining equipment designs; these designs are often more complex and may feature technologies that have yet to be proven for the application or at the scale they are now fielded.The prospect of significant automation of open pit equipment is also bound to add complexity to future equipment designs. Semi-automated features, such as drilling controllers (Aquila, 2000), have already been commercialized. Fully autonomous haul trucks have been demonstrated in open pit mines (Jackson and Zoschke, 2000). Design concepts for comprehensive teleoperation of open pit operations have been formulated (Lipsett, 1998).With this rapid availability and deployment of new technology and equipment, managers and maintainers are faced with a multitude of decisions regarding what equipment to acquire and what maintenance strategies to implement. In light of this evolution in mining equipment, it is necessary to develop better methods for making equipment management decisions (Dessureault et al., 1999; Paraszczak, 1999). The incentive for development of such techniques is that a large portion of an open pit mine’s operating cost is maintenance related, as shown in Table 1."

Jan 1, 2000

By O. Peters, D. Lascelles, R. Caldwell

Ageing tests on a crushed Cu-porphyry ore were conducted to assess the impact of sample oxidation on flotation performance. The objective of the testwork was to simulate ageing of ore that would be blasted through block caving but not milled for possibly several months. Ageing was performed in specially designed columns, using site and deionised water to keep the samples moist over the entire ageing period. Samples from each ageing interval (0, 0.5, 1, 2, 4, and 8 months) were examined for physical and metallurgical changes resulting from the ageing process through chemical analyses, size analyses, and batch flotation tests.

Jan 1, 2009

By Roméo Roussin

"The yearly production from the Asbestos Hill pit is 1,550,000 tons of asbestos ore, with a yield varying between 18 and 20 % . The orebody was exposed at the top of a hill, and initial production started without having to remove any overburden. The projected ratio of barren rock to ore, based on the present orebody, was 2 to 1. However, as it was necessary to push back the upper benches, this ratio has changed to 3 to 1. The final pit will be 2,300 feet long by 1,000 feet at the longest and widest points. The final depth will be 680 ft. A pit slope stability study was carried out and an average wall angle of 60-70 degrees must be maintained. Preshearing of final pit limits will produce good wall stability. Permanent access ramps will be 60 ft wide, with an 8 % maximum grade. Geological conditions and the low rock temperature are the major causes of the operation's drilling and blasting problems."

Jan 1, 1976

By V. K. Karra

A mathematical model for the performance of a vibrating screen is developed in terms of an oversize partition curve. This is a normalized curve for any assemblage of particles presented for screening when their size is normalized with respect to the 50 per cent passing size (d50 ) under the prevailing screening conditions. Based on the throughfall aperture (hT) of the wire mesh on the deck, the effects of oversize (% >hT), half-size under (% <0.5 hT), deck location and feed rate were evaluated using the existing screen sizing information. All these variables and also the near-mesh (1.25 hTx 0.75 hT) content (%) of the feed affect the d50. Performance data from different decks of a double-deck screen with various feed rates, size distributions and screen apertures were used to evaluate the near-mesh factor. Effects of wet screening and material bulk density are also incorporated in the model. This generalized model is useful for the simulation of a multiple-deck screen. It furnishes the sieve analysis information of all the deck output streams and therefore has a potential use in the over-all circuit evaluation when used in conjunction with relevant crushing and grinding performance models. An example illustrating the prediction capabilities of the model is given.

Jan 1, 1979

By P. Leo

Al-Mg-Si alloys are widely used as medium-strength structural materials; extrusion is the most common processing route. In the present hot deformation investigation of a 6060 alloy, the microstructure of the alloy has been analyzed in the as-cast state, after homogenization heat treatment and after hot deformation by tensile tests in the range 400-490°C and 10-4 to 10-2s-1 on both as cast and homogenized alloys. After deformation the microstructure of the as-cast alloy exhibited cavitation. The flow curves at the lowest test temperature T show a gradual softening after a stress peak, being more evident for the alloy deformed in the homogenized state in association with a high yield stress; at higher T a plateau is attained which is lower as T rises and strain rates decrease. For each fixed T, the ductility decreases as strain rate increases for the homogenized alloy whereas, for the as cast alloy, it rises with strain rate. Constitutive analysis gives Q = 240kJ1mol for the homogenized alloy in agreement with published values; this indicates a more rapid strength decline with rising T than Al, suitable for good hot workability along with the lack of cavitation.

Jan 1, 2011

By H. J. lgner

Hydraulic fills are widely used in the tabular, steeply dipping stopes of the South African gold and platinum mines as an integrated process within a daily cycle of drill and blast. There is therefore only a small time window in which to fill the geotextile bags used as primary fill containment, without the risk of loosing production. Consequently, mines tend to increase the flow rate to the stopes, although this compromises adequate drainage, consolidation and strength development during filling. Recent underground measurements inside the geotextile bag have revealed that at high rates of rise and at 25 degrees dip, the backfill can remobilise within a limited area inside the geotextile bag during filling. This sudden downward surge of backfill exerts, for only a few seconds, additional loading on the geotextile, its supporting mesh and the props. This unstable behaviour poses a serious threat as it can push props out of place, thereby damaging the geotextile bag and causing a mud slide in the stope. To reduce the risk of accidents, the phenomenon of sudden slumping was further investigated for various filling conditions in the laboratory. The results confirmed that the maximum pressures associated with the sudden slumping can be more than five times those experienced during steady-state consolidation. Based on this new insight, the current best practice for hydraulic backfilling was critically reviewed. A practical approach to implementing meaningful standards is presented to ensure safe operations in relation to the consistency of the backfill quality and the appropriate matching of geotextile characteristics with backfill properties.

May 1, 2007

By Richard W. Hutchinson, Christopher Osterman

Abstract -The Selebi-Phikwe deposits are hosted by amphibolite to granulite facies gneisses of the Limpopo belt. The sulfide orebodies are generally stratiform and conformable to the foliation of the wallrock gneiss. Sulfide remobilization has occurred during metamorphism and has produced discordant sulfide veins, called piercement structures, which project into the hanging wall and foot­ wall gneisses. These piercement structures are compositionally similar to the stratiform sulfides, consisting mainly of pyrrhotite, pentlandite and chalcopyrite. However, texturally the piercement sulfides are coarse grained and inclusion-free, whereas the stratiform sulfides are fine grained and packed with tectonically produced wallrock inclusions. The piercement structure sulfides and adjacent stratabound sulfides were sampled and analyzed for major base metals and PGE&apos;s for comparative purposes. Most of the piercement structures were enriched in Cu, Ag and Au, whereas they were generally depleted in Ni, Co, Fe and PGE&apos;s. Changing elemental associations were observed from the stratabound sulfides and along the length of the piercement structures. This and the degree of depletion or enrichment of various major and minor elements in the sulfide piercement structures may reflect the relative mobilities of metals under metamorphic conditions. The similarities between sulfide piercement structures and the footwall Cu-POE veins in some Sudbury deposits are reviewed.

Jan 1, 1994

By R. K. Netolitzky

The Weedy Lake, Tower Lake, and Wedge Lake gold deposits illustrate contrasting styles and different ages of mineralization within the same district. The discovery of these deposits was the result of systematic exploration of gold occurrences noted during research of assessment files. The Weedy Lake and Tower Lake depo its reflect a late-stage gold mineralizing event. The e deposits developed along the same major structural break, and also display simi lar mineralogy and alteration patterns. Mineralization is developed in all the lithologies present. The Wedge Lake property, while having occurrences similar to the Weedy and Tower deposits. has the more important Twin Zone which best fits a volcanogenic exhalative model. The Twin Zone has a complex structural history without a recognizable alteration halo. The setting may be proximal to a hydrothermal vent. Mineralization is hosted within a mixed ulphide/oxide/silicate facies iron formation breccia. and the gold is intimately associated with arsenopyrite. The origin and age of the brecciation is key to understanding the mineralizing event. Traditional prospecting procedures in conjunction with conventional B-horizon soil geochemistry were instrumental in the Twin Zone and Weedy lake disco,•eries. Tower Lake was a prospecting discovery partially defined by previous drill programs. This deposit was also identified by B-horizon oil sampling.

Jan 1, 1986

By A. Warczokand

The cleaning of copper smelting slag requires magnetite and cuprous oxide reduction. The slag reduction with coke, injected coal powder or bunker oil is strongly endothermic and requires heat generation by fuel combustion or the use of electric energy. The reduction of fayalitic slag with calcium carbide is slightly exothermic and the formed calcium silicate modifies the slag. Thus, the additional energy is required only for covering furnace heat losses. Results of crucible scale tests showed the rate of slag reduction approximately five times higher in comparison of the slag reduction with coke under the same conditions. It seems that the effect of exothermic reaction and slag modification with CaO at the reaction interface results in very high rate of slag reduction. Industrial scale tests carried out in the Anglo-American Chagres Smelter demonstrated the possibilities of effective reduction and cleaning of the slags from a flash smelter and Peirce-Smith converters in a Teniente Slag Cleaning Furnace. The slag reduction was carried out without any reductant or stirring gas injection, simply by calcium carbide charging through a furnace mouth, and was very fast.

Jan 1, 2007

By A. V. Tarasov

There are still a number of copper smelters in the world using the roasting and smelting process flow diagram for treating sulphide raw materials. The technical, economic and environmental performance indicators of such operations are inferior to the respective indicators of advanced processes. First of all with respect to copper and sulphur recovery: 95% and 75% as compared with 98% and over 90%, respectively. Based on the studies of the single-stage smelting process to produce white metal and blister copper conducted during recent years an analysis of the feasibility of roastingsmelting technology improvement was carried out in the Gintsvetmet Institute to substantially increase the copper and sulphur recoveries. On the basis of this analysis, it was proposed to modernize the technology and equipment within the framework of the existing process flow-sheet. The proposed modernization implies an increase in the roasting temperature; higher desulphurization degree in the process of roasting; a number of modifications in the roaster design depending on the particular conditions of a given operation; addition of lime flux to the feed charge to roasting; and transition to combined calcium-silicate smelting slags. The metallurgical and energy computations made have indicated that the proposed modifications of the technology will improve the copper and sulphur recovery up to 98% and 90%, respectively. The required capital investments have been estimated using as an example a particular copper smelter, the payback period determined taking into consideration additional output, fuel saving and a reduction in fines for sulphur emissions. For comparison, the capital cost of a smelter modernization is given for change-over to basically new autogenous Ausmelt, Outokumpu and V anyukov smelting technologies.

Jan 1, 2007

By Dirige. A. P. E.

A study was conducted for an operating mine to determine the appropriateness of its tailings material to be used for the preparation of a low modulus, high density backfill. The research was initiated due to issues arising from increased observations of compressive failure of backfill placed in stopes and inconsistent backfill behaviour (i.e. increased backfill brittleness and modulus). Backfill materials investigated were classified tailings and de-slimed tailings. Characterization of the physical properties of the classified and de-slimed tailings materials was conducted to assess the effect that these material properties would have on the strength and deformation behaviour of high density backfill products made using them. Such behaviour was investigated to determine whether differences in tailings physical properties would influence the strength and modulus character of the backfill materials. Uniaxial (UCS) and consolidated-undrained triaxial compression strength tests were conducted to determine strength performance and deformation behaviour of backfill. This paper presents the results of the backfill material characterization study and how different particle size distributions affected the strength performance and deformation behaviour of the different backfill mixes. It also demonstrates how stress-strain curves generated from material strength tests were used to evaluate variation in high density backfill mix response when such materials were subjected to unconfined and confined (triaxial) compression loading.

Aug 1, 2013

By Fred G. Hewett

The Cassiar orebody is located in a sill-like serpentinite body intrusive into the Devonian-Mississippian sedimentary rocks of northern British Columbia. Subsequent intrusion of the Cassiar batholith formed the McDame synclinorium and produced chrysotile asbestos. Present information indicates an orebody of approximately 16,277,000 tons amenable to open-pit mining, but continued diamond drilling will be needed to accurately define total tonnage and grade. A program has been developed at the mine to provide the required information on a daily basis, and work is continuing on more effective dollar-value prediction methods.

Jan 1, 1978

By J. G. Kelly, C. P. Brown

"In June 1983 a new borehole hoisting system was commissioned at Sherritt Gordon&apos;s Fox Mine. Twelve hundred tons-per-day of ore from the 2600 and 2800 levels are being hoisted to the 2000 level through an 8-jt diameter bored winze. This new method replaces the diesel truck haulage system which had been in operation at the mine since 1975.A study was initiated in 1980to determine the most effective method of achieving the required production. The study examined several hoisting alternatives including: expanding the existing trucking system; converting to electrically -powered truck haulage; and deepening the skip compartments of the existing main shaft. The alternative selected as the hoisting method most suited to the requirements was borehole hoisting.Development of the new system commenced in April 1982. Underground excavations included 700 feet of 8-ft diameter borehole, a hoistroom and headframe, storage bins, and a grizzly and rockbreaker station. Equipment installations included: a 5-ft diameter double-drum Nordberg hoist; a counterweighted Kimberley-type skip; two rockbreakers; and the steel sets in the winze. These installations were completed in June 1983. Some problems were encountered after the initial commissioning but these were solved, and since August 1983, the system has proven that the designed capacity is achievable within expected costs."

Jan 1, 1985

By Martin Grenon

This paper presents two case studies where fracture set orientation was quantified using three methods: a simple fracture pole grouping, a Fisher distribution and a Kent distribution. The three fracture orientation representations were then used as inputs for kinematic slope stability analysis. Differences showed up in the probability of sliding for all instability modes considered.

Aug 1, 2013

By WENDY MARTIN

The Eastern Townships and Asbestos Hill areas are the current asbestos-producing districts of Quebec. Mining in the two areas began in the /are 1870s and 1972 respectively. Production from the Eastern Townships is derived from rhe Serpentine Zone of ulrramafic rocks, specifically from basal serpentinized peridotite members of what are now considered to be allochrhonous ophiolitic material that was abducted onto the Early Ordovician continental margin. From south west to northeast, the rhree allochthonous asbestos-producing sections of the Serpentine Zone are designated the Asbestos Ophiolite Complex, the Thetford Mines Ophiolite Complex and the Pennington Dyke; the Pennington Dyke is considered to represent a segment of serpentinized Alpine peridotire that was fragmenred from a larger, more complete ophiolire complex. The Asbesros Hill deposir on the Ungava Peninsula lies in what apparenrly is an inrrusive sill found wirhin rhe Chukorar Group, the uppermosr group of Precambrian-aged Cape SmithWakeham Bay Belr of volcanic-sedimentary rocks.

Jan 1, 1984

By Robert Dickson

Princess colliery is operated by Old Sydney Collieries, Limited, a direct descendant of the General Mining Association of London, England, which, in the first quarter of the nineteenth century, pioneered in coal mining in Nova Scotia. The coal worked is a 5 ft. 6 in. seam known generally through the Sydney coalfield as the Harbour seam but referred to locally as the Sydney Main. Entry is made by shafts, 680 feet deep, sunk in 1871 on a headland forming the northern entrance to Sydney harbour. From them extend the main roadways of the colliery, a distance of 700 feet to the shore line and a further distance of 14,700 feet in submarine areas to a total length of 15,400 feet. It was the first colliery in Nova Scotia designed to work submarine areas. Lateral development extends across a frontage of 16,000 feet and the submarine area from which the coal has been extracted is slightly over 6 square miles. There yet remains sufficient territory ahead of the workings to assure a future life to this colliery estimated at over 80 years at the current rate of production. In this area the seam dips at 6 to 7 per cent and face workings have reached a depth of 1,690 feet below the sea level. Until 1923 extraction of the coal was by room-and-pillar, followed by the drawing of the pillars. At that date the superincumbent strata had reached a thickness of 1,400 feet, resulting in heavy weighting on the roof and severe side pressure on the coal ribs. In combination with a soft, heaving pavement this created a set of conditions involving great difficulties and expense in keeping open places driven in the solid sufficiently long to permit recovery of the coal in the pillars by methods and equipment then available. The operator was forced to resort to extraction by longwall as the only economical method of winning the coal.

Jan 1, 1948

The Anglo Platinum Mogalakwena North concentrator was one of the first three hard rock mineral processing applications to utilise a HPGR circuit in preference to a SAG milling circuit. This was driven by the extreme competence of the ore that had given rise to throughput issues on the original South Plant. Despite more than adequate capacity and performance of the individual comminution units, the circuit has struggled to obtain full design capacity. A thorough review of the integrated performance of the circuit revealed a wide range of bottlenecks and underutilised parts of the circuit arising from design issues. Interestingly, the major opportunities lie in materials handling issues and mismatch of loads about the circuit. This paper presents the high-level outcomes and the associated opportunities, and is pertinent to all HPGR circuit designs.

Jan 1, 2012

By Kevin B. Doyle

"Canada now supplies 23 per cent of the world demand for potash. Although potash is produced by many countries, Russia and Canada have the greatest reserves and capability to supply the future substantial demand over the next decade. It is estimated that demand will grow from 38,000,000 mt KCl in 1975-76 to 60,000,000 mt KCl in 1985-86. Current firm expansion plans and development underway in the world will move Russia to the forefront in supplying this demand growth. Russia will move from supplying 40 per cent of world demand in 1975 to supplying as much as 52 per cent in 1981. Canadian deposits suffer from natural disadvantages, such as high costs and risks of mine development and operation, and high-cost transportation to international markets, but experience has shown that these natural barriers can be surmounted to effectively compete in these international markets. However, Canadian potash is losing out in the race to supply the growth in the world potash demand over the next ten years because of artificial barriers raised through the unhealthy environment created by the current battle between different levels of government and the industry over resource taxation and legislation."

Jan 1, 1976

By F. -Z. Ji, G. A. Irons, M. Barati, K. Coley

The use of oxygen in electric arc furnace steelmaking is tied to the use of fossil fuels, and slag foaming. The current work examines the kinetics of carbon injection into EAF slags especially the saturation injection rate and available reaction area in the slag foam. Based on individual rate data and experimental gasification rates of carbon in the slags, the available reaction surface area in the gas bubbles was found to be around 1900¬4700 cm2.kg-slg-1 for carbon injection into EAF like slags at appropriate injection rates and steel making temperatures. The ratio of number of bubbles to number of particles is 1 to 17 and the weights of carbon per unit reaction area are 0.001-0.008 gC-cm-2. Using the relationship between active reaction area and x supplied in this study, the gasification rates of carbon in slags can be estimated with gas-slag interfacial reaction rates.

Jan 1, 2004