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By J. P. Grau, J. Z. Lu

"Thickeners/clarifiers are widely used in coal preparation plants, potash processing and other mineral processing facilities. Thickeners play a very important role in slurry treatment systems to accomplish solid/liquid separation. The demand for larger plants and the increased thickener handling capacities sometime require thickener diameters as large as 200m. The development and use of high capacity thickeners makes it possible to increase the handling capacity of these thickeners by several to more than 10 times compared to conventional thickeners. Hence, for a given slurry rate, selection of a high capacity thickener will significantly reduce the footprint of the thickener. Much higher handling rate, higher concentration of underflow, clearer overflow and lower capital cost are obvious advantages of high capacity thickeners; however, some process requirements and the concerns of operational cost, especially the flocculant cost of a high capacity thickener operation, keep some engineers selecting conventional thickeners and staying away from the high capacity thickeners. Forty years after the first high capacity thickener was developed, there are still arguments in the selection of conventional thickeners or high capacity thickeners in mineral processing. The arguments will continue unless there is a clear picture of capital cost vs. operational cost for each of the thickener types. The purpose of this paper is to analyze these costs and to provide guidelines for selection of thickeners. INTRODUCTIONThickeners/clarifiers are widely used in various slurry treatment systems. For mining and mineral processing, thickeners are an integral part of the solid/liquid separation system. The feed to the thickeners are processing slurries. The fundamental mechanism for the solids/liquid separation is for the solid particles in the slurry to gravity settle inside the thickener tank. The clear water overflows from the top of the thickener tank and is typically reused in the processing circuit, and the concentrated underflow is discharged to different downstream process systems depending on the application of the thickeners. The general requirements for a thickener operation include high density of underflow and clear overflow. Since thickener operation consists of continuous feeding, overflow and discharge of underflow, the solid particles will gravity settle against an upward flow with its velocity dependent on the feed rate and the underflow discharge rate. Higher feed rates to a given thickener produce higher upward velocities. Underflow discharge is typically relatively small compared to the amount of overflow. The upward flow tends to take particles up to the overflow. Only those particles having a settling velocity greater than the upward flow velocity will possibly settle out. Hence, thickener feed rate has to be controlled so that the required overflow water clarity can be achieved."

Jan 1, 2012

By W. D. Sinclair, R. J. Cathro, E. M. Jensen

"The Cash is one of the largest porphyry copper-molybdenum Deposits found in Yukon to date. It is 80 km northwest of Carmacks, within the unglaciated portion of the Dawson Range, and is associated with the Big Creek fault, an important tectonic feature. Part of the mineralized zone is blanketed by up to 70 m of alluvial drift . The remainder is covered by a relatively thin residual soil layer. The mineralized zone, however, was not detected by conventional stream-sediment sampling because pathfinder elements, such as Cu and Mo, have not been geochemically dispersed into the main drainage system. The deposit was discovered by a combination of soil analysis and inspection of rock fragments from small pits.Twenty widely spaced, shallow drill holes have outlined an areaover 2700 m long and 550 to over 1000m wide that grades more than 0.1% copper equivalent (% CuE = % Cu + (5 x % MoS2)). Two smaller zones grading over 0.4% copper equivalent occur within the larger area. The limits of the widest end of the deposit have not been delineated.The Cash deposit is fairly typical of high-level, calc-alkaline porphyry copper-molydenum occurrrences in the Canadian Cordillera {cf, CIM Special Volume 15) and is representative of most prospects in the Dawson Range. It is associated genetically with a subvolcanic complex of small, irregular stocks and dykes of feldspar porphyry and related breccias of Late Cretaceous age. Copper and molybdenum sulphides occur along fractures, in quartz veinlets and disseminated in feldspar porphyry and in older metasedimentary and intrusive rocks. Higher-grade zones of copper and molybdenum have associated potassic alteration. Phyllic alteration is, in part, superimposed on potassic alteration. Argillic alteration occurs locally.This paper describes the history of the discovery and the geochemical and geophysical characteristics, together .with the regional geology, and the nature and distribution of the host rocks, hypogene mineralization and hydrothermal alteration."

Jan 1, 1981

By A. Romero, M. Carvalho, D. L. Millar

"The number of underground mines replacing diesel by battery powered mobile equipment is growing worldwide. The latter produces locally zero emissions and less heat, improving air quality in the working areas, and can potentially reduce energy costs due to lower ventilation requirements and in the face of higher fuel prices. However, there is a lack of systematic approaches to evaluate the potential economic benefit of switching from diesel mobile technologies to electric ones. This paper presents a method to answer the question of whether a mine with known operating conditions should invest in battery-powered electric equipment to reduce its total costs. Furthermore, this method provides the optimal number of electric and diesel equipment in relationship with their impact on the ventilation system and the total costs of running the mine from the energy perspective. A case study of an underground mine in Northern Ontario (Canada) is presented to validate the method proposed. The scenarios studied include the specific climatic conditions of the region, and the possibility to use heat recovery for the ventilation system. Overall, results show that the use of electric mobile plants is cost competitive, especially so when electricity cost can be lowered through load-shedding strategies.INTRODUCTIONOf the multiple advantages of using electrical vehicles (EV) underground in mining, the potential increase in air quality and comfort is the most significant (Paraszczak, Svedlund, Fytas, and Laflamme, 2014). Until recently, fully battery-powered electrical underground heavy duty machinery (i.e., loaders or trucks) were not available, so that tethered and trolley assisted vehicles were the only electric alternatives to diesel powered vehicles (Bétournay et al., 2011). Today, several commercial battery-based alternatives are available (General Electric Fairchild, 2015; RDH Mining Equipment, 2015; Paraszczak et al., 2014). Operational details can be found in Ewing (2015). The main battery technology used (Lithium Iron Phosphate, LiFePO4, or LFP) was already anticipated in Bétournay et al. (2011) as a good candidate for these types of vehicles. More details on these batteries, along with state of the art and future perspectives can be found in Zubi, Dufo-López, Carvalho, and Pasaoglu, (2018)."

Jan 1, 2019

By B. van Beek, T. Goff, P. Gebski, P. Szyplinski, W. L. Ying

"Monitoring the refractory lining integrity is essential to assure the safety of the operators and to determine the remaining campaign life of a furnace. Early detection of refractory lining degradation is essential to avoid sudden furnace failures and prevent unscheduled shutdowns. In the mid-1990s a stress wave propagation technique was developed and since then it has been utilized by Hatch Non-Destructive Testing (NDT) Group to evaluate furnace linings. For the last 17 years the AU-E technique evolved in terms of hardware, software and signal acquisition and interpretation. Most importantly, based on more than a decade of commercial applications, an extensive database of various failure modes, refractory deterioration trends and material properties has been created. This knowledge base is an integral part of AU-E which progressed from a NDT technique towards a comprehensive approach for furnace condition monitoring. All of the improvements introduced over the last several years have greatly improved the accuracy of the measurements. The data analysis process has also become more time efficient making the critical results available to the furnace operators in a more timely manner. Today the AU-E technology is used on a variety of process vessels in non-ferrous, glass, chemical and iron and steel industries.In this paper we are reviewing the available techniques for furnace refractory lining measurement and discussing the pros and cons of each method. The need for continuous improvement and development of new techniques for refractory monitoring is also emphasized. Finally, we are presenting a number of case studies and comparisons between the physical verifications and the AU-E measurements."

Jan 1, 2015

By A. J. Stapleton

"This paper gives a brief description of the occurrence and development of the Needle Mountain mine at Gaspe Copper Mines, Limited and describes the trackless mining equipment used in this highly mechanized underground operation.Maintenance of the trackless equipment is considered in detail, with particular emphasis on scheduling and control, examination and inspection. All maintenance is carried out in an underground garage, and the facilities for maintenance and field repairs are also described. Maintenance costs are given for various units and the figures for different types of loading and haulage units are compared to support the trend toward larger units and the increasing use of rubber-tired loaders."

Jan 1, 1969

By K. Maruyama, T. Nagasaka, R. d. Chairaksa-Fujimoto, T. Miki

Electric arc furnace dust or EAF dust is considered as a hazardous waste but contains a significant amount of economically attractive non-ferrous metals especially zinc as zinc ferrite (ZnFe2O4) and zincite (ZnO). The hydrometallurgical process is one alternative choice because it has the advantage of low energy consumption. The leaching of ZnO from the dust is very easy. However, the complex major zinc compound in EAF dust is ZnFe2O4, which is very stable and insoluble in alkaline or acidic media under delicate conditions, and causes the low zinc recovery yield by hydrometallurgical process. Moreover, halogens and heavy metals in the dust are also problematic. In order to develop a new effective EAF dust treatment process, the authors have proposed "CaO addition process" as pre-dust treatment to transform all of ZnFe2O4 in the EAF dust to ZnO and Ca2Fe2O5. In this study, the selective zinc leaching from the CaO treated EAF dust with NaOH and NH4Cl solutions was carried out. The effect of temperature, reaction time and solute concentration were systematically investigated. All of zinc in CaO treated EAF dust was successfully leached into both solutions.

Jan 1, 2014

By M. Savich

A graphical method has been developed for the evaluation of the U.S. Occupational Safety and Health Act Noise Exposure Index and the Equivalent Continuous Sound Level. The method makes use of a noise survey form and a mechanical integrator with two sliders, and is less tedious and susceptible to error than alternative methods. The graphical method is adaptable to various codes for noise exposure and may be used with any instrument that measures noise level. One example of its application to a practical situation in a Canadian mine is given to demonstrate the procedure .

Jan 1, 1978

By M. Mohammadijoo, J. B. Wiskel, D. G. Ivey, S. Kenny, H. Henein

Cold-wire tandem submerged arc welding (CWTSAW) has recently been developed as a novel welding technique to replace the conventional tandem submerged arc welding (TSAW) process and improve the productivity of pipeline manufacturing. The process involves two electrodes with arcs and one electrically cold electrode. Since heat-input of the welding process is a key factor affecting the properties of the weld metal (WM) and the heat-affected zone (HAZ), and the additional cold-wire affects the heat introduced to the weldment, it is of interest to investigate property and geometry changes in the WM and HAZ when a cold-wire is added to the welding process. In the current research, the CWTSAW process is investigated and optimized by correlating the main welding parameters with the micro-hardness of the WM and HAZ and the geometry of the weld, i.e., the bead width (BW), penetration depth (PD), reinforcement area (RA) and coarse grained heat-affected zone (CGHAZ) area. Three statistical and mathematical methods are employed to optimize the CWTSAW process in terms of the mechanical properties and WM and HAZ geometry of a typical microalloyed steel used for pipeline manufacturing.

Jan 1, 2015

By Lise-Aurore Lapalme

Structure of the Presentation ? sustainable development and its social dimension ? challenges that mining is facing ? responses by industry ? corporate social responsibility ? the role of government Sustainable Development ? new perspective on how we view development ? consider how minerals and metals contributes to sustainable development ? challenge to better understand economic, environmental and social aspects ? make social aspects more broadly understood and appreciated

May 1, 2002

By Earl Gebhardt

The planning and design of mining panels in the Potash Corporation of Saskatchewan Inc., Lanigan Division mine Block B involved a number of investigative techniques. The techniques utilized to gain insight into the viability of mining included 2-D and 3-D seismic surveys, longhole drilling, exploration wells, photolineament, magnetic and gravity surveys, and actual room excavation.

Feb 1, 1993

By F. Melo, M. Pawlik

Fine coal aggregation in concentrated coal-water suspensions was studied through steady-state rheological measurements. The wettability of coal particles was modified by dry oxidation of a bituminous coal. The degree of hydrophobicity was monitored using film flotation. The rheological measurements revealed that hydrophobic coal particles aggregate in aqueous suspensions, over a wide pH range, and produce slurries with high yield stresses. As the degree of coal oxidation increases, the coal particles become more hydrophilic and such suspensions exhibit lower yield stresses values. The yield stress values for suspensions prepared from oxidized/hydrophilic coal become a strong function of pH and correlate well with the surface charge as determined through electroacoustic measurements. These results indicate that the yield stress of aqueous suspensions of coal, and hence coal particles aggregation, is strongly affected by the wettability of coal particles.

Jan 1, 2004

By M. J. Gole, R. E. T. Hill, S. J. Barnes

"The Agnew (also known as the Perseverance) nickel deposit and its northern extension, the Rocky's Reward deposit, form one of the world's largest accumulations of nickel sulphides hosted by komatiites. Agnew was previously classified as an ""intrusive dunite-associated"" deposit . It has now been shown that the sulphides are hosted by komatiite flows which underlie an adcumulate-textured dunite body that crystallized in a large lava channel.The rocks of the mine area have been subjected to a metamorphic temperature of550°C and pressure of up to 3 kb. The komatiites have mostly been reconstituted to olivine-amphibole chlorite assemblages. There is a zoned sequence of enstatite-, anthophylite-, talc- and antigorite-bearing assemblages inwards from the western margin of the ultramatic reflecting variations in the CO/HP ratio of metamorphic fluids.Facing directions are determined from variations in the proportions of metamorphic minerals and in rock compositions which reflect asymmetric layering in the flows . Olivine-sulphides matrix ore is hosted in a single 50 m thick, east-facing flow that is overlain by flows containing massive sulphides. Much of the massive sulphide has been physically remobilized into fold noses, faults and shear zones. Chemical diffusion of ore components has upgraded a sulphide-rich metasedimentary unit where it is in structural contact with massive ore.To the north, the mineralized flow sequence is separated from a stratigraphically higher komatiite sequence, the Perseverance ultramafic complex, by approximately 150 m of felsic meta volcanic and meta sedimentary rocks. Southward, the Perseverance ultramafic grades laterally into an olivine adcumulate body and its lower contact cuts progressively down stratigraphy until it lies directly on top of olivine-sulphide ore of the mineralized flow sequence. This discordant contact is interpreted as the base of a thermal erosion channel formed by a voluminous komatiite lava flow. This contact greatly influenced later deformation of the mineralized flow sequence."

Jan 1, 1989

By James E. Wennen

The through-put and energy efficiency of an autogenous (AG) grinding mill are adversely affected by variability in rock size and rock competency. This applies to both fully autogenous and semi-autogenous (SAG) grinding circuits. In this paper we focus on an approach to overcome the problem of inconsistent mill through-put related to variability in mill feed size and rock competency. The focus is on ores containing hard, competent rock. This approach consists of preparing feed to an autogenous mill that contains 20% coarse media rock and 80% of material crushed to pass 37 mm. Results of pilot-scale testing for two iron-ores will be presented to show that a 10% to 12% reduction in unit energy consumption is possible with prepared feed, compared with feeding the mill with conventional primary crusher discharge.

Jan 1, 2012

The Discrete Element Method (DEM) is a powerful tool for analysing the flow of charge, the energy consumption and the pattern of energy utilisation of a SAG mill. With the development of laser scanning measurement, the detailed internal working surfaces of a SAG mill can now be included in DEM models. Using scanned results for new and worn shell liners for a 32? (9.75 m) SAG mill, it is shown that the feed and discharge lifters have significant effect on the flow of the charge introducing significant threedimensionality. The effects of the resolution accuracy of liner geometry and the lower cut-off of the rock size distribution are explored. Finally, using a matched new and end of life worn liner and operating conditions taken from site surveys, the effect of wear on charge motion, distribution and energy utilisation are evaluated.

Jan 1, 2012

By R. J. Mitchell

"The use of hydraulically delivered classified tailings sands to provide ground support in large mining operations is still widespread despite recent developments of alternate backfilling methods and materials. The major disadvantages of the use of hydraulic fill are the costs and risks associated with slurry delivery. The main risk is that of bulkhead failure resulting from sand liquefaction due to insufficient operational control or due to dynamic loading from earthquake or rockburst. That risk may be eliminated by the pouring of a stiff cemented sand plug in the base of each stope prior to continuous fill pouring in that stope. An additional advantage of cemented plugs is that massive bulkheads are not needed. Instead, a temporary (removable and reusable) bulkhead can be used for plug forming.Physical model studies of fill pressures on a temporary bulkhead were carried out in a 3 m radius centrifuge facility. Fill pouring in-flight was carried out in order to model prototype stress paths. The results indicate that the average bulkhead pressure is likely to be less than 10 kPa under normal operating conditions and less than 20 kPa under the poorest anticipated operating conditions which include smooth walls, high slimes content and high water-content slurries. A portable bulkhead consisting of a central core and a surrounding sealing bladder was modelled and found to be effective. The use of different sizes of cores allowed the stress distribution adjacent to these bulkheads to be evaluated."

Jan 1, 1992

By R. Jacobs, R. E. L. Pobe

The Moab Khotsong Metallurgical Complex comprises a gold recovery circuit (Noligwa Gold Plant) and a uranium recovery circuit (South Uranium Plant). The metallurgical complex employs the reverse leach technology for the recovery of uranium; specifically, uranium extraction prior to gold using acid leaching processing. The inherent uranium species in the ore are uraninite, coffinite and brannerite. The slurry that has been subjected to the uranium leach is further subjected to solid-liquid separation to separate the uranium in solution through counter-current decantation and the solids (solids carrying all the gold), which are repulped and returned to the gold plant for gold processing. The uranium leaching process is critical to the uranium playing a pivotal role as a value adding by-product to the gold operation. The benefit of adopting this reverse leach process, for improved gold recovery, is that it exposes gold particles occluded within the uranium matrices and avails them for cyanidation. However, the drive for operational efficiency in uranium extraction must be weighed against the incremental operating cost against the backdrop of depressed spot uranium market prices. Over the years, efforts were directed at maintaining the benefit of extracting uranium to enhance gold recovery and simultaneously, optimizing the operating cost model for the uranium operation to remain relevant to the gold operation. The aim of this paper and the corresponding presentation is to give account of the uranium processing optimization journey embarked on over the years; namely, the operational trade-offs made in the process of ensuring that uranium continues to add value to the gold operation. These challenges were faced while striking a fine balance between processing cost and operational efficiencies against the prevailing depressed uranium spot market prices. Mineralogical- and laboratory tests conducted form the support basis for the results and observations articulated in the paper.

Jan 1, 2020

By Tadeusz W. Wlodek

THE known phenomenon that a test-piece of ferro-magnetic steel is magnetic after it has been broken in tension indicates that, while it is being loaded, the steel acquires magnetic properties. In the present investigation of the influence of the stress on the magnetic flux, repeated pulsating stresses of increasing amplitude, varying from zero to the maximum tensile value, i.e., pull-pull loading, were employed. The specimens were prepared from two types of carbon steel and two of alloy steel. The magnitude of the magnetic flux was determined indirectly. The voltage and mode of variation of the electromotive force induced in a coil surrounding the stressed steel specimen were measured as an indication of the varying magnetic flux within the specimen. Curves representing the electromotive force induced by the varying magnetic flux show that as the tensile load increased so also the magnetic flux increased, with a corresponding increase in measured e.m.f. At a certain stress there is a sharp bend in the voltage curve (point Win the diagram, Figure 5); this critical stress corresponds very closely with the yield stress (0.2 per cent permanent strain). Beyond this point, slight increases in the stress produce large increases in the voltage. The wave form of the e.m.f. was registered on an oscillograph. Analysis of the curves so obtained demonstrated the necessity of continuing these experiments, in order to determine the type of induced wave form associated with various types and amplitudes of stresses. In these experiments, the shape of the stress wave was sinusoidal, although the shape of the induced e.m.f. was sinusoidal only up to a certain load and became more and more complex above this load.

Jan 1, 1944

By Charles J. Zablocki, Robert J. Kamilli

"Buried, possibly mineralized granite cupolas at the Silsilah tin deposit in Saudi Arabia (lat. 26°06' N, long. 42°40' E) have been successfully located using a closely spaced electric-field-ratio profiling technique. In this study, electrical fields at 27 and 270 Hz across grounded electrodes spaced 50 m apart were measured along six traverses. This method is interpretable by inspection, unlike the dipole-dipole technique, which requires mathematical modeling for interpretation.In the study area, the technique allowed the authors to identify and distinguish among unroofed granite cupolas, cupolas with their aplite-pegmatite apical contact zones intact, strong (quartz-rich) and weak (relatively quartz-poor) greisens, dikes, faults, and pervasively argillized rocks.This method should be useful in the valuation of other shallow mineral prospects in similar settings in other parts of the world, especially deposits for which the location of vertical contrasts is important, such as veins or mineralized zones associated with the apexes of small igneous cupolas."

Jan 1, 1993

By J. G. Whellock, J. W. Matousek

"In spite of their importance to the economics of many metallurgical projects, the values and technical aspects of precious metals losses in smelting operations are relatively undeveloped subjects. This paper attempts to provide a condensed overview of precious metals losses in pyrometallurgy, using some of the limited production and experimental data available. It is intended for three general groups of metallurgists - operators attempting to improve recoveries, cost-accounting engineers making estimates of metal losses in new or modified smelting plants, and research engineers and students.Distribution coefficients of precious metals, the ratios of metal or matte assays to slag assays, are convenient means of comparing smelting processes and the tendencies of the different metals to enter the slag. For silver in lead blast furnaces this ratio is approximately 250;for gold and the platinum group metals in submerged-arc, electric furnaces it is 900. The ratio for gold and PGMs in converters varies with the degree of oxidation of the charge. The over-all cycle-average for industrial installations is tentatively estimated to be 35.IntroductionThe magnitude of precious metal s losses in pyrometallurgical operation s is difficult to assess. The primary producers are generally reluctant to discuss the subject. The by-product producers (the large sulphide smelters o f copper , nickel, and lead) might be more willing to disclose information, but these have precious metals in their feeds in such dilute quantities that accurate accounting is extremely difficult. It is not until numerous processing steps have been taken t hat the precious metals become sufficiently concentrated to permit acceptably accurate sampling and analytical procedures to be followed. Thus, knowledge of the precious metals contents o f the intermediate mattes and slags may simply be unavailable."

Jan 1, 1990

By P. Hanniala, S. Harkki, B. Andersson

"The Outokumpu Flash Smelting Process was put into commercial operation in 1949. The original process was based on the use of preheated air. The adoption of oxygen enrichment of the flash smelting process air in 1971 was a crucial improvement, especially for smelter capacity. Oxygen use according to the Outokumpu method means selection of the most suitable oxygen content for the process air on the basis of the concentrate composition, capacity and matte grade. The furnace is not bound to only one fixed degree of process air oxygen enrichment; the oxygen content may vary from 21% to 100%.The degree of oxygen enrichment and the matte grade are the most important process parameters in reducing the operating costs of the whole system, including smelting, converting and acid production. Raising the matte grade allows more efficient use of the reaction heat in the smelting stage. Sulphur is recovered in a high-strength, constant-flow gas stream. The blowing time in the converters is reduced considerably.Oxygen enrichment and high matte grade improve the energy efficiency of the plant complex as long as the surplus heat from the system is not wasted. When the operating costs and investment expenditure of the total plant complex are taken into account, a reasonably high degree of oxygen enrichment (35-80°/0) is the best alternative in practice. Existing operating smelters have achieved single-stream thoughputs of over one million t/yr of concentrates.HistoryLocal capital and operating costs as well as lower energy consumption per unit of metal produced are now the crucial factors in determining the choice of process. In the late I940s, the same reasons prompted Outokumpu to develop the original flash smelting process in Finland. Between 1900 and 1940, very few technical changes in pyrometallurgical copper production took place. However, the commercial use of the flash smelting technique began a new era in metal extraction from sulphide concentrates. The characteristic feature of the method is that the concentrate is smelted in suspension: this offers the most favourable conditions for heat and mass transfer, and thus high reaction velocities. Outokumpu was the first to exploit the known advantages of flash smelting in a commercial installation at Harjavalta in 1949."

Jan 1, 1982