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By X. Cao, X. -G. Chen, K. Liu

Due to the detrimental effect of platelet iron-rich intermetallics on mechanical properties (particularly ductility) in cast alloys, it has been essential to transform these phases into Chinese script morphology. In the present work, the effects of Mn and/or Si addition and cooling rate on the phase transformation of the iron-rich intermetallics in 206 cast alloys with different Fe contents ranging from 0.15 % to 0.5 % were systematically investigated. The results obtained showed that platelet ß-Fe and Al3(FeMn), Chinese script a-Fe, Alm(FeMn) and Al6(FeMn) can be observed in the 206 cast alloys, depending on the Fe, Mn and Si contents as well as the cooling rate. It was found that the addition of either Mn or Si favors the formation of Chinese script iron-rich intermetallics but inhibits the precipitation of the platelet phases. In addition, the combined addition of both Mn and Si has a synergistic effect on the phase transformation. Furthermore, there exists a critical cooling rate to effectively suppress the formation of platelet iron-rich intermetallics for a given alloy. The threshold cooling rate decreases with increasing Fe, Mn and Si contents. Casting process maps are established to correlate the intermetallics precipitated with alloy chemistry and cooling rate for 206 cast alloys containing various Fe levels.

Jan 1, 2014

By K. Mayhew, A. Lossin, H. Salomon-de-Friedberg

"The proportion of arsenic-bearing copper concentrates that supply the copper industry is on the increase. The current strategy of miners and smelters to blend feeds to reduce average arsenic levels is rapidly becoming unsustainable as more concentrates with even higher arsenic levels enter the marketplace. In addition, the capability of smelters to manage increasing arsenic levels to more stringent and restrictive environmental standards is limited by available process technologies.CESL Cu-As Technology is a viable technical and economic alternative to traditional smelting. It offers the advantage of simultaneous leaching and precipitation of the arsenic in a single processing step while achieving high copper extractions. The process has been piloted in six separate, fully-integrated pilot campaigns for feeds ranging from ~1% to 12% arsenic in concentration. This paper will focus on the behaviour of arsenic in CESL’s leaching/precipitation step and operational factors that influence it, and on the chemical and physical characteristics of the subsequent iron-arsenic residue that represents today’s best available technology from a long-term sustainable (capital/operating costs, metal recovery, safety, environmental) perspective.The examples provided will demonstrate copper extractions approaching 99% and arsenic deportment to residue of 99%. Instantaneous settling rates of the residue were measured at 15+ m/hr. Data from subsequent short and long-term stability testing of the residue confidently support the view that the scorodite-bearing residues from the process will be stable and provide an acceptable arsenic management practice. The technology offers increased revenue and environmental certainty for miners, smelters & refiners to support the development of metallurgically challenged copper-arsenic deposits. Furthermore, results will be presented demonstrating the technology’s ability to successfully incorporate hazardous arsenic containing smelter by-products such as dust into the process feed and simultaneously extract copper value while fixing the arsenic in a stable residue."

Jan 1, 2016

By R. C. Urquhart

Since the first use of the electric arc furnace Henri Moissan (1892) and its use by Paul Hérholdt (1902) to melt steel, it has been successfully used as a pyrometallurgical smelting tool in the production of calcium carbide, iron, ferrous and non-ferrous alloys. Commercial forms of the electric arc furnace have evolved from round, single-phase single electrode units to rectangular three electrode three-phase units to round three electrode three phase units and ultimately to rectangular six electrode three-phase units. DC electrical supply has also been used to replace the three phase power supplies in some cases. This paper examines how these electric arc smelting furnaces have evolved in size, efficiency and configuration within the constraints of the smelting process, electrodes and electrical power supply equipment.

Jan 1, 2014

By K. Schimann, H. D. Knipping, J. P. Fouques

"The Cigar Lake uranium deposit, in the Athabasca area of north Saskatchewan, was discovered in May 1981 by Cogema (Canada) Ltd., as operator of the Waterbury Lake Joint Venture.The deposit, which is devoid of direct surface expression, is located at the unconformity between the Lower Proterozoic (Aphebian) Wollaston Group meta-sediments and the Middle Proterozoic (Helikian) Athabasca sandstone, at a depth of 410 m to 450 m below surface.At the end of 1984, the deposit had been defined by 105 mineralized holes over a length of 1800 m and a width of between 25m and 105m. It has the shape of flat-lying /em 5 m to 30m thick and shows a remarkable longitudinal and lateral continuity from the information obtained to date. A well defined bulge of the unconformity underlies the mineralized zone over its entire length.The deposit appears to be controlled by an east-west trending structure within which a particular rock facies (""augen gneiss'') has developed in the graphitic metapelites of the Wollaston Group. It is surrounded by a strong alteration halo affecting both sandstone and basement, characterized by extensive development of Mg-AI rich clay minerals (illite-chlorite). The mineralization is hosted principally by the Athabasca sandstone, and consists mainly of uraninite and sulfa-arsenides of nickel and cobalt. Numerous geochemical and geophysical surveys have been carried out in the Cigar Lake area, and although no specific geochemical or geophysical anomaly can be directly associated with the mineralized body, there may be locally a good coincidence.However, a combination of several methods proved extremely useful in interpreting the regional geology and defining the drilling targets within the favourable areas.Although the Cigar Lake deposit shows many similarities with several classical deposits of the Athabasca region, it is characterized by the intensity of its alteration processes and the presence of massive, extremely high grade mineralization.At the end of 1984, the global geological reserves estimated by geostatistics on the main mineralized ""pod"" of the deposit amounted to 110,000 metric tonnes of uranium at an average grade of 12.2% U, with a precision of 25% at the 95% confidence level."

Jan 1, 1986

By W. S. (Steve) Vaughan

The Origins of Joint Ventures in Canada?s Mining Industry ? Among the most important financing structures used in our mineral industry today ? Virtually unheard of in the Canadian industry prior to the 1970s ? Borrowed from the U.S. oil and gas sector where it came into prominence in the late 1930s ? The Securities Acts of 1933 and 1934 in effect killed the sale of (equity) shares for financing oil and gas wells and start up mining companies

May 1, 2013

By A. Kishimoto, Yoshida Honmachi, T. Uda, Y. Taninouchi

Recycling of e-scrap is often performed by utilizing a pyrometallurgical Cu smelting process. Several valuable metals, including precious metals, can be efficiently recovered through the Cu smelting process. However, recovery of Sn is quite difficult because it is distributed in slag during the smelting process. Sn is used as solder and plating in electronic devices, and its recycling will be more important in the future. In light of this background, a pretreatment process that can extract Sn directly and selectively from e-scrap was developed in this study. The proposed Sn extraction process involves alkaline leaching using iodate ions, IO 3, as an oxidizing agent. We conducted leaching experiments for Sn, Sn-Ag-Cu alloy solder, and Cu, and the effective dissolution of Sn was confirmed. In principle, the electrodeposition of Sn from the leach solution and regeneration of IO3 are possible by a subsequent electrolysis process. The results obtained in this study suggest that the proposed leaching process can be an effective and useful pretreatment for Cu-smelting-based e-scrap recycling. INTRODUCTION Electronic scrap (e-scrap), including waste printed circuit boards (PCBs), is one of the fastest growing waste treatment streams in the global urban environment. E-scrap contains numerous valuable metallic elements, including Cu, Sn, and precious metals, in rich quantity. Furthermore, some metals and other materials contained in e- scrap are hazardous to human health and the environment when they are not properly managed. The recycling of e- scrap is therefore a major concern in terms of resource supply and waste treatment, and it has been performed by many companies using a variety of methods.

Jan 1, 2019

By A. Zangooi, J. A. Finch

"A frother analysis technique based on the formation of a colored solution with UV-VIS absorbance proportional to frother concentration over a certain range has been developed. The calculation of concentration requires the comparison of the sample absorbance at a selected wavelength with a linear calibration (frother concentration vs. absorbance) constructed with values collected from solutions of known concentration (standards) at the same wavelength. It has been found that concentration ranges for preparation of standards can vary widely. An integration of our experiences into a databank can offer some guidance on the selection of standard concentrations. The databank includes results from the analysis of 37 chemical reagents, commercial frothers, and natural oils used in research work or at industrial sites. Grouping frothers by similar chemical structure or origin provides a good basis for selecting the standards to approach the maximum absorbance range for the spectrophotometer in use.INTRODUCTIONA technique to determine frother concentration on samples of industrial milling streams based on formation of a colored solution with UV-VIS absorbance proportional to frother concentration has been developed. The concentration is determined by comparison of its absorbance, at some selected wavelength, with those obtained by processing a series of solutions of known concentration (standards), at the same wavelength. It is desirable to have linear calibration (frother concentration vs. absorbance) over the widest concentration range. The upper concentration can be restricted by the instrument, as there is a maximum detectable absorbance (minimum transmittance), which can be reliably sensed by the UV-VIS detector (in most cases maximum absorbance is 3)."

Jan 1, 2016

By H. Clare Horwood

"In the Little Long Lac-Sturgeon River area of Thunder Bay district, Ontario, most of the known ore deposits occur in fractures, shear zones, and zones of brecciation, in folded sedimentary rocks . In two or three instances, however, deposits occur in Keewatin greenstones and in later granitic rocks of probable Algoman age.The principal regional features in the area are the long narrow bands of Keewatin volcanic rocks and Timiskaming sedimentary formations that extend east from lake Nipigon to Long Lac, a distance of about 65 miles. The belts continue to the east for many miles beyond Long Lac and probably for some distance to the west under the waters of lake Nipigon. They are intruded in places, particularly in the north, by large masses of diorite, granodiorite, and granite. Small intrusive masses of diorite and porphyry also occur in many localities throughout the area.The Little Long Lac-Sturgeon River mining area is the youngest camp in Ontario and has been in production only since 1934.The district is readily accessible from the branch line of the Canadian National railway between Longlac station on the main line and Port Arthur, and from the Trans-Canada highway No. 17. Both these means of communication traverse the area in a general east-west direction parallel with the principal structural trend of the rocks of the region.In the Little Long Lac section discoveries were made by W. W. Smith in 1931 (Hard Rock property) , by T. A. Johnson in 1932 ( Bankfield property) , by T. A. Johnson and T. Oklend in 1932 (Little Long Lac property) , by F. MacLeod and A. Cockshutt in 1933 (MacLeod-Cockshutt property) , and by George and Frank Papineau in 1935 (Hutchison Lake property).In the Sturgeon River section discoveries were made by Powers and Silam in 1925 (Northern Empire property), T. A. Johnson in 1931 (Dik-Dik property) , and by Russell and James Cryderman in 1935 and 1936 (Sand River and Leitch properties)."

Jan 1, 1954

By Fidelis T. Suorineni

HydraboltTM is a Swellex-type dowel support element developed and manufactured by New Concept Mining in South Africa. Like Swellex, the HydraboltTM is a folded tube which can be inserted into a larger diameter hole without pushing. It is then activated by injection of high pressure water which inflates the folded tube to intimate contact with the walls of the borehole at a set pressure, normally 25 MPa. Unlike Swellex however, the set water pressure at the end of the inflation is maintained throughout the life of the dowel. An integral non-return valve makes this possible. The HydraboltTM is being investigated as a possible stress change measuring cell. This paper presents the results of closed form solutions, numerical modeling and laboratory test to date. Preliminary results indicate that the HydraboltTM can be used as a stress change monitoring cell in addition to its conventional role as a rock mass reinforcing element. If successful, the HydraboltTM will supplement microseismic monitoring systems in rockburst-prone ground conditions where they will give quantitative stress change data for both mine design model calibrations and means for proactive safety measures.

Oct 1, 2010

By N. Aydogan, H. Dundar, Å. Partapuoli, A. Fredriksson, P. Wikström, K. Tano, G. Adolfsson

The Autogenous milling of ores holds an increasing attraction as the focus moves towards reducing energy usage, both direct and embodied in grinding media. However, most of the early AG mills were converted to SAG for improved stability and increased throughput. This imposes a huge penalty in steel grinding media consumption. The LKAB iron ore operations in Sweden process highgrade magnetite through fully-autogenous milling lines to a final product P80 of about 45µm. The outcomes of P9O AMIRA research surveys, covering a wide range of mill fillings and throughputs and with different feed blends, are presented. Insights are provided on operational strategies, opportunities, the influence of feed size control and balancing the blend of competent gangue and softer magnetite. Areas of importance in the successful operation and control of energy-efficient autogenous circuits are highlighted.

Jan 1, 2012

By J. A. Finch

Samples of feed and product from a closed grinding circuit treating a heterogeneous lead-zinc ore were taken. The feed was subjected to laboratory batch grinding in a rod and ball mill with the objective of simulating the closed-circuit size distribution. It was concluded that the batch rod mill can closely simulate this product if only the over-all size is considered, but mineral-by-mineral large differences occur. If, as is suspected, the mineral sizes are the important factor in flotation, the differences could lead to problems in interpreting flotation results. An example of mineral recovery as a function of size is described to illustrate the potential problems.

Jan 1, 1979

By Y. M. Shneerson, I. V. Fomenko, M. A. Pleshkov, E. A. Ospanov, A. A. Shakhalov, S. S. Naboychenko

Low-grade copper concentrates (with copper content less than 20%) often contain impurities such as arsenic, zinc, lead, mercury, antimony and bismuth. The pyrometallurgical treatment of such concentrates is associated with several problems, which will ultimately affect the cost and the quality of copper cathodes as well as by-products. SRC Hydrometallurgy proposed a complex hydrometallurgical technology which allows the removal of impurities and the enrichment of low-grade copper concentrates to a quality which will be more suitable for pyrometallurgical processing. Laboratory batch tests and pilot plant results for the pressure leaching steps are shown in this paper. The key parameters of the leaching steps were determined and optimized. The quality of possible by-products were also determined. The developed flowsheet includes two pressure leaching steps: pressure oxidation (POX) and hydrothermal alteration (HTA). Both operations are carried out at 170°C with subsequent flotation of POX and HTA residues and recovery of copper, zinc and lead into separate concentrates for further processing. The development of the flowsheet was based on the Balkhash Zinc Plant (Balkhash, Kazakhstan), which had been non-operational since 2009. The developed flowsheet for processing of low-grade concentrates will utilize 80% of the existing equipment of the Balkhash Zinc Plant, thus leading to a significant reduction in required capital expenditure. INTRODUCTION As the age of copper mining operations advance, copper grades continue to diminish and impurity levels increase. Therefore, copper producers are forced to look for new innovative hydrometallurgical technologies which are able to handle low-grade raw materials and solve problems associated with impurities in an economically justifiable way. New technologies allow to extract valuable components selectively and to process low-grade concentrates which had previously been marked as non-technological and economically unviable. Hydrometallurgical technologies for processing of copper-containing materials can be divided into two main categories: chloride and sulfate (atmospheric, autoclave and bacterial) based technologies. Since the 1970s, many autoclave techniques for the processing of copper-containing materials have been developed and implemented (Naboichenko, 2002; Dreisinger, 2005; Habashi, 2009; Shneerson, 2011). The mineralogical composition of the ore (or concentrates), geographical location of the deposit, distance from industrial areas, availability of existing treatment facilities, availability of skilled labor, cost of electricity and cost of neutralization are some of the factors which are usually considered when the appropriate technology is selected (Halbe, 2002).

Jan 1, 2019

By B. Arsenault

Aluminum coatings can provide galvanic cathodic protection for several metals and alloys, In order to be a suitable protective solution on structural components, the mechanical integrity of the component must be preserved, In particular, fatigue properties are a challenge for thermal-spray protective coatings on mechanical structures, To address the issue of the fatigue integrity of 7075 aluminum alloy with an arc-sprayed protective coating, different surface preparations prior to arc spraying were considered, In the present work, a feasibility study was performed using laser ablation as a surface-preparation technique before or during arc spraying of coatings, This was collaborative effort between the LERMPS laboratory in France, the National Research Council Canada and the Royal Military College of Canada, Both fatigue and adhesive properties of aluminum coatings were evaluated in relation to substrate-surface-preparation techniques including laser ablation (Protal® process), grit blasting and shot peening. Results indicate that a combination of key conditions, including the use of nitrogen as the arc spray gas, shot peening, and proper laser energy density for ablation, provide high fatigue resistance of metallic coated 7075 alloy substrates. Specimens prepared under these conditions show a similar fatigue resistance to uncoated substrates.

Jan 1, 2005

By J. T. Birkholzer, M. Rutenberg, K. -H. Lux, R. Wolters, J. Rutqvist, L. Blanco Martin

In this paper, we present numerical results corresponding to the Thermal Simulation for Drift Emplacement (TSDE) test, conducted in the Asse salt mine (Germany) between 1990 and 1999 to simulate reference repository conditions for spent nuclear fuel in rock salt. This test is of significant relevance for nuclear waste disposal in salt because extensive research and measurement programs were set up for the experiment. In our numerical study, we use two sequential simulators, TOUGH-FLAC and FLAC-TOUGH, and we investigate two-way coupled processes, focusing on thermo-mechanical analyses due to the main effect of heating. The two simulators used have recently been updated and are able to deal with large strains and creep processes. Moreover, specific constitutive relationships and coupling functions for rock salt and crushed salt under repository conditions are available. Within the framework of a benchmark exercise between Lawrence Berkeley National Laboratory and Clausthal University of Technology, the same scenario has been modeled in three dimensions using the two simulators mentioned. The main objective of the current, first stage of the benchmark is to evaluate the capabilities of these two simulators to predict relevant processes under repository conditions for high-level nuclear waste in saliniferous media. The comparison of the numerical predictions between them is very satisfactory, leading to a successful code-to-code verification. The comparison between measurements and numerical results shows that the most important processes are captured by the codes and constitutive models used. However, some differences exist between measurements and numerical results. These differences will be addressed in the next stage of the benchmark exercise, in which a parameter fitting effort will be undertaken. Overall, from the results obtained it can be concluded that TOUGH-FLAC and FLAC-TOUGH have the necessary capabilities to reproduce relevant processes under repository conditions for high-level nuclear waste in saliniferous formations.

Jan 1, 2015

By Frank Baczek, R. Q. Honaker, D. P. Patil, B. K. Parekh

Fine refuse slurry impoundment is a requirement for the coal industry to dispose the fines. Impoundment maintenance is an on going problem for the coal industry and its breakage creates environmental as well as financial problems. Deep Cone thickener technology which has been successfully applied in the alumina industry to dewater red mud was evaluated for fine refuse slurry. Preliminary obtained in a pilot-plant test showed that properly flocculated conventional thickener underflow slurry could be thickened to about 52.5 wt % solids and could replace belt filter press. The Deep Cone thickener was also found to dewater clean coal slurry to about 70 wt % solids. Further testing of the unit at other coal preparation plant is in progress.

Jan 1, 2004

By Mei-Yan Yang, Qiu-Ying Wang, Ltd. Yunnan Yuntong Zinc Co., Guo-Mu Chen, Meng-Yang Huang, Peng Zeng, Guo-Feng Li

"Historically, alot of jarosite was found in the leaching residue when leaching indium from secondary zinc oxide materials. The reasons for the formation of indium bearing jarosite were theoretically analyzed. The influence of controlling the acidity and the addition of reagents on the indium leaching yield during secondary zinc oxide processing was investigated. In order to increase the leaching yield of indium, a measure of controlling the creation and destruction of jarosite was proposed. The production data shows that the leaching yield of indium was increased from 60 to 96%, and the content of indium in leaching residue simultaneously decreased from 900g/t to 100–200g/t when implementing such controlling measures.INTRODUCTIONIndium does not occur as independent minerals in the earth’s crust and is mainly associated with complex sulphide minerals. Specifically some sphalerites can contain as much as 900g/t of indium. Most indium is recovered from by-products of copper, lead or zinc metallurgy. Therefore, the research on the recovery of by-products in non-ferrous metallurgy is important(Sinclair et al, 2006). The main technologies used for this objective in China include: •,pre-neutralization-reduction-precipitation indium process(Yu et al, 2008), •,countercurrent oxidizing acid leaching process and sulphation roasting-water leaching process(Cao, 2005), •,oxygen pressure acid leaching of zinc concentrate-P204 extraction process(Yang et al, 2006), •,doubleacid leaching-solvent extraction process on lead dross from a reverbatory furnace flue dust(Liu, 2003),•,an acid leaching-solvent extraction process on smelting ash(Zhouet al, 2005). Although high pressure and extreme conditions can be used to improve extraction from high iron bearing indium residues(autoclave processing), mild extraction with lower cost and lower environmental impact are preferred.This paper describes both how the indium extraction using mild conditions in a secondary zinc circuit was quite low and, how through XRD and chemical analysis jarosite formation was found as the main cause. The paper then proceeds to discuss a method for improving the leaching yield and the application of this method in industrial practice."

Jan 1, 2016

By Ahmad Abdollahi

Many factors affect mechanical properties of hypoeutectic Al-Si alloys. As examples the presence of impurities such as Mn and Fe due to the formation of intermetallic phases, additions of small amounts of alkaline earth metals and cooling rate in consideration of Si formation, they all have an impact on mechanical properties of hypoeutectic Al-Si alloys. In this investigation, the effect of Fe content into the specification range of A357 alloy, the addition of different modifiers consisting of Na, Sr and Ca for the alloy of A356 and different mounting techniques for separately cast test coupons of hypoeutectic Al-Si alloys using the lost wax method were studied. The results showed that using material with lower Fe content and addition of modifiers improve mechanical properties. Also different mounting techniques resulted in different mechanical properties.

Jan 1, 2004

By M. E. Stutt, R. H. Rehder

"The mining industry is taking advantage of the increased performance resulting from the use of variable speed A C drives for large motors. This technology provides increased efficiency under the variable speed and torque requirements of such drives as mine hoists, conveyors, and air moving equipment. The technology does introduce voltage spikes on the voltage wave form that stress the insulation system to a greater degree than would occur with a constant voltage source. These voltage spikes must be considered in the design of the insulation system used for these motors.BackgroundHistorically the insulation systems for large AC motors were designed to withstand with reasonable life the voltage stresses of a 60 Hz constant sinusoidal voltage. One of the design tests is a voltage endurance test that requires the application of a 60 Hz voltage from conductor to ground equal to four to five times normal and establishing a time to failure. These higher than normal voltages accelerate the normal aging process by causing extensive partial discharge activity (corona) within the insulation system and the time to failure is a relative indication of insulation life.In addition to the voltage endurance test at 60 Hz, the individual coils are subjected to a surge voltage test to establish the withstand capability of the turn to turn insulation under switching surge conditions. The surge voltage is a fast rise time, 0.2 microsecond to crest value, voltage spike that can be caused by a circuit breaker or contactor closing operation. These voltage spikes can have a crest value of greater than 3.5 times the normal line to ground crest voltage of the normal 60 Hz power supply. The standard withstand test value is thus 3.5 times normal line to ground voltage. Because the voltage surges or spikes occur mainly during start and stop switching conditions, voltage endurance under these conditions has not been a major factor in insulation system design."

Jan 1, 1995

By A. Navarra, Norman Toro, T. Marín, Fernando Ayala

The quantitative techniques to evaluate the enhancement of a particular unit operation should consider the corresponding changes to the adjacent unit operations. For example, the expansion of off gas handling capacity should consider the corresponding changes in converter cycle times, matte grade, and other operational parameters, that can provide the optimal system-wide benefit. In general, the upgrading of smelter equipment is risky due to the size of capital investment, as well as any unforeseen impacts on rest of the operations. However, this risk can be mitigated by applying the principles of Front End Loading (FEL) in the formulation of multiphase re-engineering projects. The initial phases of engineering are relatively inexpensive, and determine whether or not to pursue the subsequent phases that are comparatively more expensive. Each phase of engineering depends on increasingly detailed descriptions regarding the critical phenomena that can effect design decisions; the increasing levels of detail may result from numerical simulations, as well as laboratory and plant trials. The quantitative framework should be sufficiently flexible to accommodate these increasing levels of detail, regardless of the particular phenomena, so that it may evolve throughout the project. The current article describes the combined usage of mass balancing, thermochemistry and multiphysics, in the development of discrete event simulation (DES) and finite differences (FD). The incorporation of finite differences into a DES framework depends on adaptive time-stepping, to determine threshold-crossing times, e.g. when the matte temperature surpasses a critical level that necessitates the addition of cold charge. The hybridization of DES and FD is appropriate for multiphase smelter development projects, as it supports semi-continuous material flows, operational policies and scheduling, as well as unexpected events and trends, in increasing levels of detail. This type of framework will support the installation and tuning of modern control systems, including state-of-the art sensors and machine learning algorithms.

Jan 1, 2019

By Ferenc Molnár, David H. Watkinson

Abstract - Cu-Ni-PGE footwall ore deposits were studied in the McCreedy East and Whistle mines along the North Range, and the Lindsley and Little Stobie mines along the South Range of the Sudbury Igneous Complex. The footwall ores in these localities differ from typical magmatic Fe-Ni-Cu- PGE deposits in the Sudbury mining camp: they have higher Cu/Ni ratios, higher PGE content, veinlike appearance and ubiquitous association of ore with hydrous silicates. Results of comparative fluid inclusion petrography and microthermometry of footwall ores indicate that high temperatures (300°C to 480°C) and heavy-metal rich saline (up to about 40 NaCl equivalent wt% salinity) fluids were associated with the formation of the PGE-rich footwall ores at moderately high pressures (around 2 kbars). However, several, possibly independent fluid circulation stages were also found at the different localities and there also are differences in detailed characteristics for ore-forming fluids especially comparing data from the North Range and the South Range. Thus, in addition to the high temperature and salinity of fluids, there are local variations in the nature of hydrothermal processes. These differences may be related to the diverse origin of fluids (magmatic, metamorphic, and formational brines) and their differing extents of interaction with the compositionally different footwall lithologies.

Jan 1, 2001