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By L. E. Djingheuzian

Introduction Cylindrical grinding mills have been used for a long time, but during many years of testing no methods were established that gave consistent results. The work by both scientific investigators and operators led very often to contradictory conclusions, and each millman was very much 'on his own' when trying to find the limits for working of his ball-mills. Fred C. Bond, in the introduction to his paper on Wear and Size Distribution of Grinding Balls, freely states that the mathematical immaturity of the grinding process "is the cause of many inefficient designs and installations as well as of much poorly oriented experimental work", and evidently he sees the solution of all our grinding problems in the discovery of the fundamental laws "which can change the empirical art into a mathematically exact science". While the writer is in complete agreement with Mr. Bond that grinding is governed by fundamental laws which can be expressed by mathematical formulae, there are so many variables in grinding, all interwoven with each other and mutually influencing each other, that the coalescing and merging of all these variables into a harmonious mathematical whole appears to be a homeric job. However, a light appeared on the horizon when it was proposed that power be used as an index of the grinding operation. It is pertinent to quote Gow, Guggenheim, Campbell, and Coghill from their paper on Ball Milling, in which they say: "Much of the past literature devoted to the subject has been concerned with the Kick-Rittinger dispute over evaluating grinding, or with dissertations on ball paths and the closely allied impact versus attrition hypotheses or with the exclusive consideration of certain specific variables, such as mill speed or circulating load, irrespectve of the other factors in operation. Such subjects may be dismissed with but little discussion in what may be called, by comparison a new philosophy in the stud of ball milling. Briefly this 'new philosophy' consists ' of using power as an index of the mill operation, and investigating grinding from the standpoint of set and induced variables with emphasis on the latter". But it is safe to assume that it was the work by E.W. Davis, H. E. T. Haultain, F. C. Dyer, A: M. Gaudin, J. Gross, S. R. Zimmerley, and others, that cleared the path for the authors of Ball Milling and induced them and A. W. Fahrenwald to look farther afield and thus to establish a far-reaching relationship between the power and capacity and the diameter of the ball-mills.

Jan 1, 1949

By K. Ebrahimi-Nasrabadi

The dependence between the extent of conversion of cryptocrystalline magnesite to caustic magnesia was studied experimentally in the temperature range of 400?1200 °C and for calcination times up to 8 h. A TGA?DTA analysis showed that decomposition begins at temperatures as low as 340 °C and is completed at 600 °C. Measurements of specific surface area (SSA), iodine adsorption number (IN), crystallite size, and loss on ignition were carried out to characterize the product quality. It was found that while all the parameters are dependent on the extent of calcination, densification of the product caused by grain coarsening affects their final values. As a consequence, SSA and IN went through a maximum with time. The study showed that high quality caustic calcined magnesia can be produced in a narrow range of temperature (600?650 °C) and time (1?4 h). Medium quality caustic calcined magnesia can be made within a wider range of parameters.

Aug 1, 2013

Despite the claims of energy efficiency and the considerable development that has gone into dramatically extending rolls? life and facilitating rolls? change-out, in the six years since the last SAG conference, only a few HPGR operations have entered the realm of mineral processing. Risk barriers to the take-up of new equipment or processes are: a massive increase in materials handling issues as well as in the number of pieces of equipment required, low total circuit potential energy savings, and similar or higher capital costs. An alternative route is to make use of the complementary strengths of the HPGR and SAG in hybrid circuits. Minimising materials handling issues, providing an ideal balanced feed to the AG or SAG mill, and improving controllability through shifting grinding load as the RoM feed changes, are all potential major advantages to this approach. Conceptual circuit layouts, based on real measured ore and equipment data, are presented here to illustrate the potential production upside, the reduction in operating costs and the reduction in the physical and energy footprints.

Jan 1, 2012

By J. S. Fox

"Besshi-type Cu-Zn (-Ag-A u ± Co) deposits are tabular, stratiform volcanogenic sulphide bodies which are usually associated with mafic volcanic rocks of oceanic or intra-plate geochemistry, but which can also be found locally with ultramafic volcanics or subvolcanic mafic intrusions. A thick sequence of continentally-derived clastic sediment usually encloses both the mafic volcanics and the ore. Besshi-type deposits form subaqueously, in epicratonic rifting environments, more-or-less proximally, and as a result of hydrothermal convection in their subjacent mafic volcanic - clastic sedimentary piles. They belong to a rift -related metallogenic spectrum that includes sediment-hosted and Cyprus-type base metal deposits, and may diller genetically from these mainly with respect to rate and degree of crustal extension. Modern analogues to these deposits are f ound in the submarine volcanogenic sinters of the Gulf of California rift system.The associated lithologies and tectonic selling of Besshi-type deposits clearly distinguish them from Kuroko-type ores. This difference also seems to be reflected in their lead isotopic character. For example, leads from Besshi-type deposits in the Sanbagawa belt of Japan and from the Blue Ridge belt of southeastern U.S.A. lie on extended anomalous lead lines and have lowslopes in 207Pb/204 Pb - 206Pb/ 204 Pbspace (Sato and Sasaki, 1980; Leriuray, 1982), wheras those from most Kurokotype mining districts exhibit only narrow isotopic ranges and lie near or on the orogene growth curve (e.g. , Franklin et a I., 1981). More over, where Besshi- and Kuroko-type deposits are found in the same orogene, the former often occur earlier in the tectonic cycle than the tatter (e.g., Japan, the Norwegian Caledonides, the southern Appalachians and south-central Finland).Besshi-type deposits are not confined to any particular part of the world, or to any geological epoch. Moreover, in many mineralized belts, Besshi-type deposits are the predominant volcanogenic ore type. On a world-wide scale, deposits of this type therefore constitute an important base metal resource."

Jan 1, 1984

By W. D. Watson

"Early in mine development at Quintette Coal Limited major problems were encountered with the fleets of primary equipment which seriously hampered production. These major fleets (cable shovels, hydraulic shovels, hydraulic drills and electric trucks) have consequently been the focal point of maintenance efforts. Some were prototypes in the Canadian mining scene and brought with them new concerns to test their skills. The problems were studied and the category and areas which were having the greatest impact on the reliability of the equipment were determined. Once defined, priorities were established and a program was initiated which was designed to accomplish a resolution. Resulting from implementation of this systematic approach, over the past three and one-half years, the fleets are now giving good reliability and industry standard availabilities. Along with these significant achievements, cost per operating hour on some of the equipment fleets has decreased substantially and continue a downtrend through 1987. This paper identifies the problems and describes the resolutions. IntroductionIn the early years of the mine development, Quintette Coal Limited (QCL) experienced production shortfalls due to problems with the major excavator and haulage fleets. A large fleet of hydraulic excavators had been purchased, and QCL was among the first northern users of all hydraulic blasthole drills. They were also using some prototype equipment and encountered problems which were not common on other types of equipment or were unknown.Because of these unique problems and lack of experience from other mines to draw on, an analytical approach was taken to areas and associated causes of the delays affecting the availability and reliability of equipment. This was done by dividing the equipment downtime into seven classifications of delays, i.e. maintenance, electrical, hydraulic, mechanical, damage, service and preventative maintenance, and tires; and then each was expressed as a percentage of total downtime. Subsequently each of the delay classification was divided into categories e.g. electrical to six categories - wheel motors, main alternator, relays, cards, no propel, lighting and 24 V system. Then, the basis for further study had been established.From this preliminary analysis of historic records, it was possible to determine the areas which were causing the majority of the downtime. These areas were then analyzed to evaluate causes and to determine possible solutions to the problem s. This paper addresses the major fleets, their problems and eventual solutions. Plea se bear in mind that the over-all objectives were to increase physical availability and reliability."

Jan 1, 1988

By Lloyd F. Dunham

"Crucial to the implementation of new computer-based information systems at Sudbury Operations of Falconbridge Limited was a data communications network that would take computing power to the various mine and plant sites. Falconbridge required a capability to provide on-line data entry, inquiry, and reporting capabilities in three geographical areas, six mines, two mills, a smelter, approximately fifty shops, seven warehouses and numerous administrative offices throughout the Sudbury basin.Conventional cabling methods were rejected based on the projected cost of installation of necessary cables; lack of flexibility to meet the changing requirements of the mine environment; and the risk of losing service to an entire area depending on solitary communication lines.Instead, Falconbridge selected and installed a Data Carrier System (DCS) and Packet Switching Communication System from Teltone Limited, Markham, Ontario. This combined system ""piggy-backs"" computer data over voice-grade twisted pair wire, bringing data to the associated PBX equipment. From there data packets are assembled and routed to the central computer site where they are disassembled for entry into the host machine.Falconbridge has been successful in using existing technology to solve communications problems in a difficult environment. Plans for the future of this network will increase its utilization for technical and real time data communications in addition to the business systems workload it now handles. The Computer Services group in Sudbury is confident that the data highway will handle communications traffic well into the future.IntroductionIn late 1984, the Sudbury Operations of Falconbridge Limited undertook a review of their existing business computer systems. The results of this review indicated that there was an opportunity to improve the timeliness and quality of information coming from the existing computer-based systems while achieving an investment payback by undertaking the project. The greatest benefits from this project would be achieved if the computing tools could be delivered to the employees that were the day-to-day users of the data. Falconbridge's existing business systems were oriented to the batch mode of processing. An alternative solution to using the existing programs had to be found."

Jan 1, 1988

By O. P. Garg

Based on improved methods of collection and analysis of geotechnical data, slope angles have been steepened in some mines of the Iron Ore Company of Canada at Schefferville, Quebec. This paper describes the slope design case history for Fleming NO.3 mine and illustrates the application of modern techniques. The new design has resulted in significant financial savings due to a reduction in required waste stripping.

Jan 1, 1978

By Leslie B. English

"HistoricalWHILE DIGGING caves and underground passages for living quarters, primitive man must have had some means of illumination. Most likely he used pieces of wood or slim bundles of reeds or grasses as torches, perhaps steeped in animal fats to give more light. If this is so, we may accept these as the first means of underground illumination. Very little was clone to improve lighting devices for many generations, but slowly there was developed a fount holding fatty oils, with a spout in which was inserted a form of wick.Actual mining. for metals first of all, was started about 3,000 B.C. Some of the old Greek and Roman records refer to the use of torches underground, and some evidence of clay lamps has been found. Candies came into use some time during the first century A.D. When coal mining began about the 14th Century in England, candles were used for illumination because of the ease of manufacturing and handling them. Open oil-lamps came into use early in the 16th century -Agricola, in his De Re .Metallica, written about 1540. pictures a miner with such a lamp. However, the expense of these was so great that candies still continued as the general means of underground lighting.Unfortunately, as miners went deeper underground, they encountered a mysterious gas which. upon coming in contact with open lights, flamed violently, resulting in explosions and accompanying loss of life. The first reference to the results of these gas explosions appeared in 1621. No help seemed to be available. The gas was given off when the coal was mined and the miners could not see without lamps. Attempts were made to use the phosphorescent glow from partly decayed fish, fish skins, and fungus, also to bring daylight clown into the workings by means of a series of • mirrors; •but these means of illumination proved to be impracticable."

Jan 1, 1955

Eagle Plains Resources? Exploration in the Northern Cordillera ?Eagle Plains Resources Ltd. (EPL) is actively exploring for Zn-Pb deposits in the northern Cordillera in both carbonate-hosted and shale-hosted (sedex) environments. ?This presentation will review some of the significant carbonate-hosted Zn-Pb showings occurring in the Mackenzie Mountains, NWT and make limited comparisons with sedexdeposits in the adjacent Selwyn Basin.

May 1, 2006

By D. R. Nagaraj, Napoleon Tercero, Raymond Farinato

"Dialkyl dithiophosphinates are a unique class of collectors used in the flotation processing of Cu- Au, complex polymetallic, and precious metal ores. They are known to exhibit higher selectivity and flotation rates for Cu sulfides, galena, and precious metal values in the presence of other gangue sulfides, than the traditionally used collectors such as dialkyl dithiophosphates and xanthates. They also have an attractive HSE profile. Historically, for most reagents used in flotation, practical methods of chemical usage have preceded detailed scientific understanding of how they work; this applies also to dithiophosphinates. Recently, however, the research community has shown significant interest in this chemistry, and numerous studies have been conducted to understand the fundamentals of interactions of dithiophosphinates with several base metal sulfides and precious metals. A critical overview of fundamental studies, laboratory ore flotation, and plant practice of dithiophosphinates is given in this paper. The findings from these studies are rationalized by drawing on concepts and insights from coordination chemistry. A comparison between the interactions of dithiophosphinates and dithiophosphate analogues with various minerals and metals is also made throughout. We believe that such a critical analysis/overview will be invaluable in identifying gaps in knowledge regarding this important set of compounds, which in turn may provide a basis for the design of studies that can advance understanding of their flotation performance. INTRODUCTIONDialkyl dithiophosphinates are an important member of the class of thiophosphorus compounds that are widely used in flotation beneficiation of base metal sulfide and precious metals ores. Ore flotation studies and plant practice experience have demonstrated their unique properties compared to the traditionally used sulfide collectors such as dialkyl dithiophosphates (their closest analogues) and xanthates. The predominant dialkyl dithiophosphinate used in the industry today is sodium diisobutyl dithiophosphinate (a.k.a. DIBDTPi; AEROPHINE® 3418A1 introduced by American Cyanamid in the late 1970s; Figure 1). The widest application of AEROPHINE 3418A is found in complex polymetallic ores of Cu-Pb-Zn-Ag, Pb-Zn-Ag, and Cu-Zn where it has demonstrated improved recoveries (and flotation rates) of sulfide minerals of Cu, Pb and Ag and selectivity against sphalerite, iron sulfides, and penalty elements (Mingione, 1991). More recently, it has also been used as a collector in the processing of Cu, Cu-Ni, and Ni ores (Guitard et al., 2015) and Cu-Au ores (Dunne, 2005). In general, it is considered to possess the collecting power of xanthates together with the selectivity (against pyrite) of dithiophosphates (Hope et al., 2003a, 2003b), while requiring lower dosages than those reagents (Guitard et al., 2015). AEROPHINE® 3418A has also found an important place in several targeted formulations to improve flotation performance. Other benefits of this reagent include higher flotation rates, having a better HSE (health, safety and environmental) profile2 compared to xanthate, and exhibiting resistance to hydrolysis and oxidation (Guitard et al., 2015). Compared to diisobutyl dithiophosphate (DIBDTP), which is known to contribute significantly to frothing (often leading to over-frothing), AEROPHINE® 3418A is observed to be froth neutral (i.e. it does not alter the existing froth characteristics). As is the case for other flotation reagents, the design and application of AEROPHINE® 3418A has preceded understanding of its behavior at a fundamental level. Recently, there have been numerous fundamental and application studies designed to develop a better understanding of its interaction with sulfide minerals and precious metals. This should help in optimizing its application in flotation and provide a basis to better rationalize its unique selectivity and activity characteristics. Past studies on the interacti"

Jan 1, 2016

By M. D. Vance, G. R. Corbett, S. D. Butt

Surface wave imaging is a relatively new seismic technique that generates subsurface depth images without having to drill boreholes into the ground, and is rapidly becoming a standard tool in non-destructive geotechnical characterization. This paper presents a case study of the application of these surface wave techniques to image shallow abandoned mine workings at the Montague Gold Mines district near Dartmouth, Nova Scotia. This district has numerous steeply dipping narrow vein workings from historical mining activity, and has actively subsiding and collapsing crown pillars. Due to the rugged conditions at the site and the relative narrowness of the openings (often less than 1 m), a surface seismic system was developed that had improved portability and lateral resolution over other available seismic imaging systems. Seismic surveys were conducted over two sites where independent evidence indicated the presence of shallow mine workings. At one site, a comparative gravity survey was also conducted. The seismic data was processed to generate velocity vs depth images. Overall, the velocity images show vertical zones of zero velocity in the same lateral positions where historical mapping, current subsidence and gravity surveys indicate the presence of steeply dipping workings. Further, the velocity sections are consistent with the thickness of the till cover at each site and the possible weakening of crown pillars at one of the sites.

Jan 1, 2005

By Matthew D. Meyer

SMART, an association of surface mining companies formed in 1995 to develop a coordinated approach to technology development for the mining industry, has recognized the need for the establishment of a worldwide database that continuously collects mining equipment data and provides metrics related to productivity and cost. Under the auspices of SMART, Syncrude Canada, Suncor Energy and Albian Sands Energy (three oil sands mining operations located in northern Alberta) have established a pilot project for mine benchmarking. This presentation will include a review of the pilot progress including: ???Data gathering techniques: means of collection and storage, proposed practice for data control and normalization, access to data/reports and format for data. ???Reports/analyses for individuals, across groups, within the total industry pool and publicly. ???Security and confidentiality of information belonging to identified parties. ???Sharing of best practices among members. SMART has identified two key deliverables to ensure success of the project. First, data supplied from surface mines must be validated and normalized to common definitions and then analyzed to provide participating companies with regular reports that allow them to understand their position and resultant opportunities to achieve world-class performance. This model maintains granularity of the data for each operation that can then be recombined into standard comparisons or specific indices as required. The general categories of: operating delays, maintenance downtime, standby, and scheduled downtime, have been used to frame comparisons. Second, participating companies are looking to go behind the indices to identify and share best practices that distinguish particular operations. The spirit of cooperation between the companies involved in the pilot project is meant to be a model for future expansion of the benchmarking project.

Apr 1, 2005

By Ian Orford, Ken L. Boyd

"Can the ever-increasing tonnages of ore and waste being mined today be accommodated simply by using bigger and better crushers? This paper updates the principal author’s earlier publication, “Crushing Plant Design and Layout Considerations” (SME Mineral Processing Plant Design, Practise, and Control, 2002). It reviews the latest primary crushing and large cone crusher designs. Its goal is to help consultants and operators select the optimal equipment and custom-designed items in the material handling flowsheet from the mine to the mill, maximizing operating hours per year.INTRODUCTIONAre larger crushers the answer to meeting the demands of existing or new mining projects for increased tonnage? The principal author’s previous paper in the year 2002 on ""Crushing Plant Design and Layout Considerations"" provided a detailed design and layout review for the design of primary and fine crushing (Secondary, Tertiary, Quaternary) mineral processing facilities. Some of the conclusions in this previous paper had predicted that larger crushers for primary and fine crushing would be beneficial and contribute to the further development of mineral processing. Larger crushers for primary and fine crushing applications are now available.The rock size reduction process, from the mine to the selected milling process facility has not changed since man first broke a rock to get at the interesting mineralization within. The rock size reduction process circuit from the mine to the mill can be summarized into four (4) stages:• Stage 1: Mining ( Rock Breakage and Fragmentation)• Stage 2: Pre-Screening (Scalping)• Stage 3: Primary Crushing• Stage 4: Fine Crushing (Secondary, Tertiary and Quaternary; the crushers used in this stage are identified by the titles which usage has conferred on them)Plant throughput and ore delivery schedule will form the basis for flowsheet design and equipment selection. Once a project's design criteria and the mine plan has been established, the actual circuit's utilization percentage (percentage of hours when the circuit is being utilized) can be optimized for each of the four stages. The mining and process departments are the key stake holders in the selection of the final comminution circuit and both departments should be familiar with and contribute to the design of the circuit."

Jan 1, 2016

Mine Safety in Chile ?Since the year 2000 fatality rate averages 34 per year ?1% of world mining labour force but 8% of world?s mining fatalities San Jose Mine Safety ?From 1998 to 2010 eight fatalities ?In 2003 mine inspectors recognized no second means of egress and a raise system was developed ?In 2006 182 workers were injured, 56 of them seriously ?In January 2007, there was a fatality after a rock burst, and the government ordered the mine closed ?Less than a year later the mine was back in operations. It had not complied with some of the basic safety measures ordered. One of those measures was to complete the escape way ladder.

May 1, 2011

"10.1. IntroductionAs discussed by Westland (1981), the six platinum-group elements (PGE) belong to the Group VIII transition metals, to which iron, nickel and cobalt also belong. The chemical similarity between these nine metals accounts for the fact that they tend to be concentrated together as a result of geological processes. These processes started to effect the distribution of these metals at the very beginning of the earth's history.The first line in Table 1 gives the concentration of nickel and certain other Group VIII transition metals in carbonaceous chondrites, those meteorites with a composition that is believed to reflect best the composition of our planetary system apart from hydrogen and helium. The second line is the estimated concentration of the same elements in the earth as a whole. It is seen that these two estimates are quite similar, the earth being perhaps 2 to 3 times richer in these particular metals than the planetary system as a whole. The reason for this is not fully understood, but it may be due to the earth being formed by the accumulation and capture of a greater proportion of iron (and therefore siderophile-rich) than stoney (and therefore siderophile-poor) planetesimals than the planetary system itself.The third line in Table 1 is the average composition of the crust of the earth. With the exception of iron, all of the Group VIII transition elements are rare in the crust, present at concentrations of It tOO to Itt ,000 of that of the bulk earth. This is because the outstanding chemical characteristic of this group of elements is their siderophile nature; that is, their tendency to alloy with metallic iron. Because of this, once the earth became molten very early in its life history, these elements dissolved in the molten iron present at this stage and were removed from the outer accessible parts as this dense liquid sank to the centre of the earth to form the core. Although iron was the main instrument of concentration of the Group VIII metals, its much greater over-all abundance and its ability to combine with oxygen more easily than the others in the group means that significant amounts still remain in the oxidized portions of the earth.The fact that most of the Group VIII metals are available to use in workable concentrations at all is that they are 5 to 30 times more concentrated in the earth's mantle than the crust, as shown in line 4 of Table I. There has been a constant, if slow, interchange of matter between the mantle and the overlying crust throughout most of the earth's history and, under certain circumstances, this interchange has given rise to economic concentrations of metals."

Jan 1, 1979

By Robert Drummond

Away back in the eighties of the last century, when Sir Charles, then Doctor, Tupper, was not only a prominent but a dominant figure in the political life of Nova Scotia, his opponents brought the railing accusation against him that he was the foremost of egotists because of his frequent use of the personal pronoun. I heard Tupper speak and had no sympathy with the railers, because I could not well see how the pronoun could be dispensed with without laying himself open to a charge of affectation. I shall make reference in what follows to incidents in which I have taken part, and shall be at no pains to dispense with the pronoun, even though thereby I lay my-self open to the charge of being a pupil of the deceased states-man. EVENTS LEADING UP TO THE ORGANIZATION OF THE PROVINCIAL WORKMEN'S ASSOCIATION The Springhill Mining Company began development work at Springhill in the early seventies of last century. So vigorously was the work prosecuted that in 18 7 4 two slopes, the east and the west, were in active operation, with a considerable. output, the east slope on occasional days producing 800 tons. The President of the Company, the late Senator McFarlane, was a Nova Scotian, the other directors were mainly merchants from St. John, N.B. From the first the enterprise was an .astonishing success, due in the greatest part to its geographical position, and in large part to the untiring vigilance of the directors, a majority of whom visited the collieries at short intervals, thereby keeping the manager, much of the time, on tenter hooks.

Jan 1, 1924

By James B. Templeton

"IntroductionWith the steady rise of the cost of coal and freight, the time is now ripe for an investigation into the feasibility of using the heat pump for heating purposes in fairly remote industrial areas.The gold mines of northern Ontario seemed to be a most likely place for the application of the heat pump.It was decided that the first step in the investigation would be to determine what economic advantage was to be gained by using the heat pump and thereby determining whether a further and more detailed research programme was warranted.If we can use the heat pump with economic advantage, we can reduce our mining costs and make a worthwhile contribution to our national economy by reducing the import of U. S. coal.The investigation was conducted under the auspices of the Nipissing Fellowship and directed by Professor R. E. Barrett of the Department of Mining Engineering, University of Toronto.With the able guidance of Mr. C. S. Gibson, of the Mines Accident Prevention Association of Ontario, the author visited the following mines: Mcintyre-Porcupine, Delnite, Dome, Lake Shore, Wright-Hargreaves, Kirkland Lake, Macassa, and Kerr Adcliso11.In all cases, the management and technical personnel of these mines were most co-operative and helpful in supplying information and ideas.It should be emphasized at the outset that the design and operation of the heat pump itself is by no means complicated or even new. The reason we hear so much about it today is because there have been improvements in compressors, motors, and heat exchangers in the past few years, and because fuel and freight rates have risen to such a point that, in some cases, the heat pump now has an economic advantage over other methods of heating."

Jan 1, 1950

By S. K. Kawatra, S. J. Ripke, T. C. Eisele

It was determined by the authors that the water that remains in the filter cake after filtration in iron ore concentrators can contain several hundred times greater concentrations of calcium ions and other cations, due to surface chemical effects carrying the ions along with the water. Filter cake from two plants was analyzed. The water retained in samples of magnetite concentrate filter cake in Plant 1 contained 5088 ppm calcium and 5995 ppm magnesium, while the Plant 2 filter cake contained 231 ppm calcium and 119 ppm magnesium. These levels were dramatically elevated compared to the water that was removed from the concentrate by filtration for recycle to the plants (9 ppm calcium/15 ppm magnesium for Plant 1, and 11.9 ppm calcium/9.3 ppm magnesium in Plant 2). In addition to possible effects on agglomeration performance, the presence of these cations also affected the efficiency of filtration. In order to reduce the effects of these cations on filtration in Plant 2, carbon dioxide was injected into the slurry before it entered the filter press. This was found to increase filtration rates by up to 23.7%. Comparison of the results from the two plants shows that the concentrations of cations present in the filter cake will vary greatly from plant to plant, with correspondingly large variations in their effects on plant operations.

Jan 1, 2004

By Peter A. Adcock, Rob Fraser

Interest in monitoring nucleation overpotential in electrometallurgical processes dates back some 40 years or more. Conversely, remarkable progress has been made in recent years on describing in detail the processes involved in the formation of thin films by electrodeposition. The newer body of work underscores a need for greater clarity in speaking about the role of nucleation and in the acquisition and interpretation of nucleation overpotential measurements – the aim of this paper. In electrometallurgy, it is generally desirable to form deposits that remain smooth, compact, and relatively fine-grained while the deposit grows to a thickness on the order of 5-10 mm, about 100 times thicker than technological thin films. Hence, we distinguish two kinds of nucleation that can result in formation of new grains:- (1) initial nucleation (onto the substrate surface) of islands that coalesce into growing deposit, and (2) ongoing nucleation of new grains on the deposit surface long after the substrate has been covered and ceases to have a direct influence. Nucleation overpotential of the first type should be measured on an electrode surface truly representative of a real industrial substrate. The second type requires judicious choice of electrode material – an “ideal foreign substrate”. In general neither the industrial substrate nor native metal to be deposited is suitable for measurement of the second type of nucleation overpotential, because of interference by other processes. For the future, clear terminology is needed to distinguish these two types of nucleation potential. The second is the one for which the type of plot dubbed by Moats and Derrick as an “Adcock plot” and by us as a “Kerby-Adcock plot” was first conceived and correlated with relatively thick zinc electrodeposits. The data of Moats and Derrick showing trends for copper electrodeposition on stainless steel and on copper electrodes are interpreted within this framework.

Jan 1, 2016

By Lawrence Devon Smith

"What is Due Diligence?Within the mining industry the term “due diligence” is used to describe a detailed data review, generally in connection with the purchase or sale of a mineral property, the approval of a large capital expenditure, or the borrowing of a large sum of money.The term originates in the requirement of the board of directors of a corporation to “act honestly and in good faith ... and exercise the care, diligence, and skill that a reasonably prudent person would exercise in comparable circumstances” (OBCA, 1994). Furthermore, the law assumes that a corporation (or its board) will have exercised due diligence in the acquisition of an asset and, therefore, knowingly (in the absence of fraud or deceit) will have taken on the liabilities and obligations associated with the asset (Nelson, 1994). This is the familiar “Buyer Beware”.Directors are liable for their decisions except “if the director relies in good faith upon financial statements of the corporation represented … by an officer of the corporation or in a written report of the auditor, or a report of a lawyer, accountant, engineer, appraiser, or other person whose profession lends credibility to a statement made by any such person.” (OBCA, 1994).Hence the importance of reports prepared by professionals. They provide confirmation that the directors have exercised due diligence in the performance of their duties. For this reason these reports are referred to as due diligence studies"

Jan 1, 1997