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By Roy Norcross, Stephen Gos

For over 100 years Degussa has worked together with the min­ing industry not only providing quality products but also develop­ing technologies to support these products through value added goods and services. For cyanide, these technologies include leach enhancement processes such as PAL™ and Solidox™, and cyanide detoxification with peroxygen based processes such as SILOX™ and Caro's acid using our DegOX™ technology. Degussa has also made important advances in how sodium cyanide is packaged and shipped with our liquid NaCN plant joint venture with MSI, CYANCO in Winnemucca, Nevada, and our Advantage SLS™ solid to liquid cyanide delivery system. All of these innovative technologies developed to support NaCN in mining, provide value to our customers and show Degussa's commitment to Responsible Care·11.1 and dedication to product stewardship. With Responsible Care and the customer in mind, Degussa has developed Advantage CCS™ cyanide control system, which will soon be available for the North American market. Currently there are several CCS units in service installed by Degussa AG (Germany), and we are in the process of designing the next gen­eration of the CCS which should be completed by late '98. Based on our experience working with gold and silver mines all over the world, there appeared to be an opportunity to further assist our customers by providing a better more automated way to control their cyanide additions. By providing the mine with an accurate method for maintaining their desired cyanide levels in their leach circuits, we could help them avoid underdosing and the associated gold and silver losses, and overdosing the cyanide which not only wastes cyanide but may increase treatment costs as well. In the early 1990's, when we began to introduce our CCS units, there were several cyanide controllers and on-line analyzers avail­able. However, they appeared to be too complicated and not made to stand the harsh conditions inside a mill. This resulted in exces­sive downtime and poor analytical results. We also found that many units would be installed but not commissioned by the sup­plier. Based on these observations, along with filtration and con­trol problems on some existing units, Degussa decided to design its own cyanide control system based on our extensive knowledge of cyanide chemistry, using the best components available worldwide.

Jan 1, 1998

The key to the successful debt funding of a new mining project, whether in economically established or developing nations, is the submission of a comprehensive feasibility study. The feasibility study forms the basis from which the resource banker can construct financial models which govern the amount of available funds, the conditions which control the supply of such funds and the time period over which the loan may be repaid. The bank will wish to ensure that the feasibility study is the best representation and confirmation of reality possible because this model is the basis of the loan security package. Thus the study will be vigorously interrogated by independent experts in all its elements including the ore reserve, mineability, metallurgy, operating and capital cost profile, environmental factors and management. A well constructed feasibility study, undertaken by well recognised and respected independent consultants can save the client company a great deal of real and opportunity costs especially in relation to project timing. Once constructed and operating, the mining project may face one or more completion tests in relation to the loans provided. The genetics of such tests often relate to either the ability of the operating company to become solely responsible for the repayment of the loan or to be rewarded by lower interest rates or some other mechanism. Strong professionalism, accessible records, good checking procedures and high quality, competent site management will greatly assist the client company passing these tests. A record of well established technical competence with its bankers may well assist a company in the establishment of a mezzanine loan for the early development of its next project, thus allowing an earlier return of dividends to shareholders.

Jan 1, 1995

By Donald E. Cummings

Measures appropriate for the control of the silicosis hazard in mining cannot be formulated precisely, but sufficient knowledge1-l9 has accumulated during the past quarter century to permit the suggestion of useful, though partly empirical, rules for its alleviation. The industrial hygienist today recognizes that the peril incurred by the inhalation of harmful dust is a function of two variable factors—the degree of harmful exposure and the specific susceptibility of the exposed individual to pulmonary injury. Control of the danger arising out of prolonged contact with pernicious airborne particulate matter is consequently best exercised by influencing both of these recognized variables. Obviously the problem has two broad aspects—one, medical; the other within the province of the engineer. I—Factors Comprising Degree of Individual Susceptibility Thorough investigations conducted among miners who have labored for years in the presence of recognized silicosis hazards usually reveal an impressive difference in the injury incurred by men whose exposure to dust has been nearly identical. After a quarter century underground, one individual is short of breath and incapacitated with miners' complaint, while a fellow workman suffers no pulmonary embarrassment and is in good health. Physicians ascribe this oft-observed difference in reaction to individual susceptibility and express a universal regret when they deplore the fate that chose to make the predisposed youth a miner rather than a farmer. To trust the health of miners to fate at the present time is even more unfortunate, because many of the factors that influence man's susceptibility to dust are known, and can be accurately determined by competent medical methods. Among the most important factors comprising susceptibility to injury by dust are the anatomical peculiarities of the individual's respiratory mechanism, his physiological response to the inhalation of dust, his previous dust, exposure, the existence of pulmonary infections or other pathological processes in his lungs, his age,

Jan 1, 1940

By M. C. Leverett

The behavior of mixtures of immiscible liquids in porous solids is of rapidly increasing interest to those engaged in the production of petroleum. The operation of artificial water-floods and the control of natural ones immediately raise questions concerning the fundamental nature of such processes. Moreover, it is now recognized that often water occurs dispersed throughout the rock from which the oil issues into the well,' and thus tends to move toward the well simultaneously with the oil. The work reported here is a laboratory investigation of the simultaneous, steady-state flow of oil and water through the same column of uncon-solidated sand. It is thus directly related to the situation in which water occurs in oil-producing sands; it may have less direct implications for the displacement of oil from sands by water. However, it is to be clearly understood that the experiments to be described were performed primarily to obtain information of a more or less fundamental nature, and are not an attempt to reproduce, on laboratory scale, any part of an oil field. The dynamic behavior of a system in which oil and water are flowing simultaneously through sand is best described in terms of its "effective permeability" to either phase. For incompressible fluids flowing through a system of uniform cross section, the effective permeabilities to the two phases, in darcys, may be defined by the equations: Ko = PA6A [la] and Ku = Q [lb] In order to put the results obtained on a comparable basis for different sands, the effective permeabilities will be stated as fractions of the normal permeability of the sand; i.e., fractions of its permeability to a homogeneous fluid. Algebraically, these fractions are: KO' = Ko/K, and KWr = K,/X [2a] and [Zb]

Jan 1, 1939

THE millng methods employed in the Mount Lyell Mining and Railway Company's mines are, perhaps, less known to the milling world than those of other important districts, due to the geographical remoteness and isolation of the Mount Lyell field,but they present many features which are unusual, and should be of interest to the mining engineer. Typical mining is carried out on an open-stope system, details of which are the result of local experience and evolution, and of which the outstanding feature is that the ground is so worked as to be largely self-supporting by virtue of domical form given to the stope roofs. It is locally termed "rill" stoping,' but differs widely from what is generally understood by that designation, chiefly in that the "rill" or slope is developed in every direction from a central focus, and not merely in directions followllig the strike of a lode or ore-body whose longitudinal dimensions are very much greater than its width. Such terms as "donie stoping" or "arched-back stoping" would be more appropriate and descriptive.The company's active operations' at the present time extend to the Mount Lyell and North Lyell mines, and, though the fundamental principles of stoping methods are the same in each, the dissimilarity of the ore-bodies, both in nature and mode ofoccurrence, necessitates considerable variation as to details to meet the respective conditions. The Mount Lyell pyritic body lends itself to the adoption of the .system in its simplest and almost ideal form, and a description of stoping in this mine willserve best to illustrate it, while later reference to details of practice in the North Lyell mine will indicate how it may be varied to meet more difficult circumstances.

Jan 1, 1915

By E. S. Leaver

THE amount of gold that occurs in a ton of milling ore from most of the large-scale copper mines is so small that unusual care and special attention are necessary to recover it. In some cases the gold is not considered important enough to warrant daily assays of the various products. Considering the large tonnage of copper ores that are now concentrated by flotation, as computed in a recent review, the gross gold content is surprisingly large, probably amounting to over 10 million dollars per year in the United States. The indications are that in many of the copper-milling operations with gold content under $1 per ton, only 50 per cent. of the gold is recovered in the flotation concentrates. Lime is generally used as a depressant for pyrite in the flotation circuit. The authors have shown that high lime or a solution high in calcium ions is also a depressant for gold. Their experiments on several well-known ores show that by careful regulation of the alkalinity of the mill solutions, a higher flotation recovery of the gold can be obtained, together with equally good copper recovery in a good grade of copper concentrates. In cyanidation for the recovery of gold, the best accepted practice demands that the mill solutions be tested and regulated by simple chemical reactions at definite periods during treatment or with each change in the treatment. It is similarly important for the recovery of gold that the solution in the flotation circuit be analyzed for calcium ions at regular periods and at each step in the flotation practice. The lime should be added when and where needed and not in excessive amounts at the head of the mill.

Jan 1, 1931

RISKGATE is an interactive online risk management system developed by the Minerals Industry Safety and Health Centre (MISHC; University of Queensland) to assist the mining industry in implementing continual improvement in management of major unwanted events so maximising health and safety performance. A comprehensive body of knowledge has been compiled from diverse mining industry experts for risk management of tyres, collisions, fires, isolation, strata underground, ground control open cut, explosions, explosives, manual tasks and slips/trips/falls. This paper presents an overview of the RISKGATE body of knowledge captured specifically for the management of unwanted events that stem from the handling and use of explosives (drill and blast) within surface coal mining operations. The knowledge presented is divided into a series of initiating events (listed below) within which there are further degrees of classification based on design, operation, and management concerns. Initiating events: ? Loss of control of explosives and associated chemicals in storage on site ? Loss of control of explosives and associated chemicals during transport ? Loss of control of explosives and associated chemicals during manufacture ? Loss of control of explosives and associated chemicals during handling and blast operations ? Loss of control of explosives and associated chemicals during disposal The system guides the user in generating substantive and leading-edge controls to assist in the design, management and reporting of drill and blast operations to meet stringent internal and external requirements. From a broader industry perspective, RISKGATE provides an environment for knowledge capture and knowledge exchange to drive innovation and best practice in the identification, assessment and management of risk. By capturing operational knowledge from industry experts, RISKGATE provides a cumulative corporate memory at a time of high personnel turnover in the coal industry.

Aug 1, 2013

By Hedge AS

Mt Whaleback is one of the largest open-cut iron ore mines in the world. Haulage cost is the single largest component of operating costs at the mine. Past studies towards alternatives to truck haulage have recognised the potential viability of an in-pit crushing and conveying system, dependent on the proportion of uphill haulage. After seventeen years of mining Mt Whaleback still contains more than 1,000 million tonnes of ore, needing 1,800 million tonnes of waste removal to extract it. What was once a quarry has now turned into a large open pit. The increasing proportion of uphill haulage, the need to replace ageing 120 ton and 200 ton trucks and the necessity of achieving and maintaining a higher stripping ratio prompted, in 1984, the initiation of a new feasibility study into the viability of alternative material handling systems. A semi-mobile in-pit crushing and conveying system was found to be most suited to Mt Whaleback conditions. The East Pit was selected as the best location based on the analysis of haulage profiles measured on long term incremental mine plans. A capacity of 22 million tonnes per year was considered achievable by the proven technology currently available. A detailed estimation of capital and operating costs of two systems - one with trucks only and another with trucks, crusher and conveyor - for the removal of 22 million tonnes per year of waste rock, showed substantial cost savings achievable by the proposed system. An economic evaluation of the two systems established the advantages of constructing the in-pit crushing and conveying system. This is now under construction and will be commissioned in early 1987. Experience gained in constructing and operating this installation is expected to influence decisions on similar installations in future.

Jan 1, 1986

By Donald E. Cummings

MEASURES appropriate for the control of the silicosis hazard in mining cannot be formulated precisely, but sufficient has accumulated during the past quarter century to permit the suggestion of useful, though partly empirical, rules for its alleviation. The industrial hygienist today recognizes that the peril incurred by the inhalation of harmful dust is a function of two variable factors-the degree of harmful exposure and the specific susceptibility of the exposed individual to pulmonary injury. Control of the danger arising out of prolonged contact with pernicious air- borne particulate matter is consequently best exercised by influencing both of these recognized variables. Obviously the problem has two broad aspects-one, medical; the other within the province of the engineer. I-FACTORS COMPRISING THE DEGREE OF INDIVIDUAL SUSCEPTIBILITY Thorough investigations conducted among miners who have labored for years in the presence of recognized silicosis hazards usually reveal an impressive difference in the injury incurred by men whose exposure to dust has been nearly identical. After a quarter century underground, one individual is short of breath and incapacitated with miners' complaint, while a fellow workman suffers no pulmonary embarrassment and is in good health. Physicians ascribe this oft-observed difference in reaction to individual susceptibility and express a universal regret when they deplore the fate that chose to make the predisposed youth a miner rather than a farmer. To trust the health of miners to fate at the present time is even more unfortunate, because many of the factors that influence man's susceptibility to dust are known, and can be accurately determined by competent medical methods. Among the most important factors comprising susceptibility to injury by dust are the anatomical peculiarities of the individual's respiratory mechanism, his physiological response to the inhalation of dust, his previous dust exposure, the existence of pulmonary infections or other pathological processes in his lungs, his age,

Jan 1, 1938

By Thomas C. Atchison

An understanding of the physical processes involved in breaking rock with explosives will lead to better blasting techniques. In this chapter known rock breakage principles will be outlined, some conjectural ideas will be discussed, and areas needing further study will be pointed out. The principles outlined will serve as a basis for the design of blasting rounds described in the following chapter. 7.2-1. Factors Important to Rock Fragmentation. The efficacy of explosives as tools for rock fragmentation lies in their ability to deliver almost instantaneously large amounts of energy to a limited portion of the rock. When an explosive charge is detonated in a drill hole, its energy is released in a very small fraction of a second in the form of gas at extremely high pressure and temperature. The mechanics of the transfer of this energy to the rock and the resulting breakage are complex and not completely understood. Factors that have been identified as important to the fragmentation process may be grouped in three categories: explosive parameters, charge loading parameters, and rock parameters. EXPLOSIVE PARAMETERS. Explosive parameters known to influence breakage are density, detonation velocity, detonation impedance, detonation pressure, gas volume, and available energy. Detonation pressure is probably the best indicator of an explosive's ability to break solid hard rock. Detonation pressure is roughly proportional to the product of density and the square of the detonation velocity. The relative ability of different explosives to transmit their pressure to stress in a given rock is function of their detonation impedances. Detonation impedance is the product of density and detonation velocity. The volume of gas released in the explosive detonation undoubtedly is of importance, at least in the later stages of breakage, and is probably

Jan 1, 1968

By R. S. Archer

IN the microscopic examination of aircraft-engine parts made of heat-treated alloy steels, the writer has been forcibly impressed by the failure of the usual etching processes to disclose any but gross defects in heat treatment. It seemed particularly desirable to bring out the grain size of the steel, which is indicated in the ordinary etching processes chiefly by the change in orientation of structure from grain to grain. After various attempts, a fairly successful method has been found, which is here presented in the hope that it may be of use to those who have occasion to examine these steels in the heat-treated condition. The specimens worked with have been mostly chrome-nickel steels heat treated (that is, hardened and tempered) to a Brinell hardness of around 300. A few experiments with other specimens will be referred to later. Briefly, the method employed consists in etching the steel about 10 min. in a fresh solution of picric acid in ethyl alcohol, and then rubbing off the smudge of carbonaceous matter on moist broadcloth. Different samples of almost identical analysis; heat treatment, and physical properties (including resistance to impact) respond quite differently to this treatment. In some, the grain boundaries are developed quite readily, while iii others, especially ill those whose grain is unusually fine or in which the final hardening heat, has not quite obliterated the previous crystallization, the results are more obscure. The exact time of etching to secure the best results also differs for various samples, and the greatest success is usually attained by a process of "tinkering." Such a process is illustrated in a series of micrographs, the first six of which were taken at a magnification of 300 diameters.

Jan 1, 1919

By Will H. Coghill

In this investigation, the low-grade red iron ores of Alabama were examined by the use of "heavy solutions."' Ores are generally ground preparatory to concentration and as long as the concentrators make suitable products the effectiveness of the grinding is likely to be unquestioned; but when suitable products are difficult to make, an investigation becomes imperative. In such a case a dissection of the ore might be made to find the cause of the trouble. Such a condition of unsuitable products exists in the low-grade red iron ores of Alabama. They are difficult to concentrate. To be sure it might be said that the concentration of iron ores is a new thing and that the ore-dressing methods are undeveloped, but a glance at the industry reveals an abundance of methods and devices for almost all imlaginable conditions. Concentrating machinery has not been tested in this investigation. When the properties of the ores have been gleaned, the machinery may be used more effectively. Alabama Low-grade Red Iron Ores The Bureau of Mines has undertaken by laboratory methods to select the best means of concentrating the low-grade iron ores of Alabama. These ores constitute the parts of the ore bed left by selective mining. If more of the ore bed could be included in the current output, the mining cost would be reduced and longer life of the district would be insured. This advantage would be reflected by added permanence of churches, homes, schools and every undertaking in the commonwealth. The red ores chosen for this study of effectiveness of grinding are too low in lime to meet the requirements of the blast furnace. If lime is

Jan 1, 1927

By J. A. Woolf, E. S. Leaver

The presence of soluble base metals in precious-metal ores usually precludes cyanidation as the best method of treatment. The laboratory experiments described in this paper show the possibility of cyanidation of gold-silver ores containing less than 0.5 per cent. of cyanide-soluble copper and the effect of zinc in the cyanide solution. Part I.—Copper in Cyanidation The proposed process of cyanidation of precious-metal ores containing copper is based on the regeneration of about 80 per cent. of the cyanide used in the dissolution of the copper. The method of regeneration involves a combination of the sulfide and the acid precipitation of the copper and silver. The resultant solution is made alkaline with lime, and the gold is precipitated with zinc dust. Solubility of Copper Minerals in Cyanide Solution In order to determine the solubility of copper minerals, including metallic copper, under the usual conditions for cyanidation, experiments were conducted with synthetic ores. Each ore sample was prepared by mixing the particular pure copper mineral with barren sea sand. Both the mineral and sand were ground to pass 100 mesh before they were thoroughly mixed. The percentage of copper in each head sample was determined by direct assay, excepting the metallic copper sample, which was computed on weights before mixing. Table 1 gives the results. Azurite, bornite, chalcocite, cuprite, malachite and finely divided metallic copper are readily and completely soluble under the usual conditions for cyanidation. Enargite and tetrahedrite are sufficiently soluble to cause an excessive loss of cyanide, and they also cause fouling of solutions with arsenic and antimony. Precious-metal ores containing small percentages of chalcopyrite or chrysocolla may give satisfactory returns with the usual cyanidation.

Jan 1, 1930

By John Mastoris, Kostis Dragasakis, Kostas Kouklidis, Shkurtë Gashi, Halil Berisha, Jenuz Bulica

Titan Group’s environmental policy and Sharrcem’s Corporate Social Responsibility (CSR) are the driving forces behind the development and implementation of a comprehensive Rehabilitation Plan at Dimce Quarry, which is the main raw material source for Sharrcem Cement Plant since the 1970’s, located in the municipality of Hani i Elezit in Kosovo. Based on an Environmental Impact Assessment Study and the approved Mining Plan and also on the principles prescribed in the Guidelines on Quarry Rehabilitation, released by the Cement Sustainability Initiative of the World Business Council for Sustainable Development (WBCSD-CSI), Sharrcem has adopted a quarry operation and rehabilitation process in line with the best practices in the mining and cement sector. This paper discusses the background for the development of the rehabilitation plan and the results of rehabilitation activities, as have been implemented over the last few years. The main objective of the progressive rehabilitation plan at Dimce Quarry is to restore the depleted pit and return it back to the original land owners for resettlement. To date approx. 3,4Ha of former mining area has been restored by backfilling and levelling of the depleted closed pit and returned back to owners, who have built their houses and turned it into a living area again. This Quarry has turned out to be a real composition and practical example of preserving and returning back the natural resources in a state compatible with the surrounding environment and with respect to the needs of the local stakeholders. The motivation for business to engage in rehabilitation activities in the first place lies in the belief that the development and implementation of a progressive and practical Quarry rehabilitation plan and restitution of the land will deliver significant environmental and social benefits that outweigh the long-term rehabilitation costs, while maintaining the company’s reputation.

Jan 1, 2017

By Claus G. Goetzel

PRESSING of powdered metal parts is best done in the direction of the shortest extension of the piece, to avoid too great a loss of pressing force through internal [ ] friction. As long as curved surfaces, recesses, or offsets occur only parallel to this shortest axis of pressure, no special difficulties arise: the cross sections, perpendicular to the pressure, do not vary, nor does the shape of the parts change during compression except for a gradually reduced thickness (Fig. IA). The problem becomes more difficult, however, when the curved surfaces or recesses are perpendicular to the shortest axis of the part (Fig. IB). Two processes for molding uniformly dense parts with complicated shapes from powdered metals are described in detail in this paper. Both can be employed successfully by those trained in the art. The first refers to curved parts; the second is especially adapted to parts having one or more recesses or steps. Both methods, as set forth here, are applied under the condition that presents the more difficult problem. For clarity, before description of the two practical methods, the variable factors in molding powdered metal parts will be reviewed, then an idealized procedure will be considered briefly. VARIABLE FACTORS IN MOLDING POWDERED METAL PARTS Compression Ratio Compression ratio is defined as the proportion of the final relative density of the compact to the apparent density of the powder. For iron powder of an apparent density of 3.0, for example, a compression ratio of 2 1/2 : I would be required to produce a compressed compact of 7.5 density; whereas for another iron powder having an apparent density of only I.5, a compression ratio of 5:I would be required to produce the same density. The lower the powder's apparent density, the greater must be the compression ratio for pressing compacts of high density.

Jan 1, 1945

By W. Griffith

The purpose of this paper is to make public record of new information in regard to the sustaining power of artificial mine-roof supports (not timber props), the result of investigations recently made in the anthracite coal fields of Pennsylvania. First.—By the "Scranton Mine Cave Commission," appointed to investigate the mining conditions under the City of Scranton. Second.—By the "Pennsylvania Mine Cave Commission," appointed by the Governor to investigate the general subject of mine caves in the anthracite region of Pennsylvania. Third.-—By the personal researches and tests made by the author in an effort to secure a better artificial mine-roof or surface support. During the progress of the work of the Scranton Mine Cave Commission, the Engineers for the Commission, Messrs. Conner and Griffith, being aware of the general lack of exact information in the engineering profession as to the strength of the ordinary artificial mine-roof or surface support, and particularly the stronger kinds, such as mine cogs, rock piers, etc., had tests made at the Fritz Engineering Laboratory at Lehigh University, to determine the sustaining power under various compressions of the several kinds of artificial mine supports in use in the anthracite region of Pennsylvania. A report of these tests wasincluded in the report of this Commission, which was published as Bulletin No. 25 of the United States Bureau of Mines, Washington. A similar series of tests, more extensive and more elaborately planned, were subsequently made for the Pennsylvania Minc Cave Commission at the U. S. Government Testing Laboratory at Pittsburgh, Pa. The report of this Commission was made to the Governor, but has not yet been published. The author, during his connection with the Scranton Mine Cave Commission, observed that of all the various devices employed for sustaining the roof of coal mines, the one universally used and the best

Jan 1, 1918

A mining companyÆs approach to managing the risk of theft of explosives and initiating devices should be underpinned by an organisation-wide policy developed with internal and external consultation. It should be based on the principles of sound proactive risk management, planning, monitoring and remedial action. This paper aims to provide mining (and construction)organisations with the rationale and many of the tools they need to control explosive security risks. As with all legislative compliance, they are best managed by incorporating the statutory and legal requirements into company policies, management systems and plans, operating procedures and culture. This is the approach that has been adopted in this paper. Trends we should expect: more prescriptive legislation and stricter government regulations; enhanced enforcement and more prosecution; more sophisticated detection systems, eg airports; additional compliance costs; additional vigilance on record keeping; improved risk awareness and risk communication; wider use of explosives policies, management systems and plans; and additional security staff with investigative skills.It should be noted that mining companies will be required to play their part in reducing the likelihood of explosives, intended for mining purposes, being wrongfully used to threaten, hold to ransom or to injure individuals or members of the public or to produce property damage. This will be done by putting in place safeguards to reduce the risk of theft of explosives while they are under their control. On that basis, this is a business risk assessment rather than a hazard risk assessment. A conclusion of this paper is that mining companies can and should play their part in reducing the supply of explosive materials that can then be used for illegal activities. In fact, mining companies have always had this duty, but now the stakes are higher û æcomplacency no longerÆ.

Jan 1, 2004

By Sadan Kelebek, Gerhard W. Heinrich, Peter F. Wells, Peter J. Whittaker

"Based on plant mineralogical data & circuit modelling, a pilot plant campaign was conducted at Strathcona Mill to identify options for improving the performance and operating flexibility of the copper-nickel separation circuits. Emphasis was given to options for combined treatment of the two feed streams (primary nickel ore rougher concentrate and copper ore circuit concentrate) to obtain more flexibility in the use of existing column flotation capacities. The pilot test results demonstrated that circuits which incorporated preconcentration prior to column flotation gave the best metallurgical results. Maximum column carrying rates were also related to the preconcentration. Predictions that increased circulating loads from the column scavengers would improve copper-nickel separation performance were confirmed.IntroductionThe copper-nickel separation circuits at Falconbridge's Strathcona Mill produce a high grade (>30% Cu) copper concentrate most of which is treated at the Falconbridge Kidd Creek smelter near Timmins. The remaining nickel concentrate which still contains approximately 20% of the feed copper is combined with other lower grade nickel/copper concentrates and shipped to the Falconbridge nickel smelter. The separation is required because of the limited capacity for copper processing in and downstream from the nickel smelter. Since no nickel is recovered at present in the Kidd smelter, the challenge is to minimize the nickel content of the copper concentrate.At present there are two independent separation circuits treating the rougher concentrates from the copper and nickel circuits as shown in Figure I. The minerals treated are mainly chalcopyrite and pentlandite but there is up to 25% of the copper present as cubanite in the copper ore. The circuits were kept separate because the flotation rates and froth characteristics were very different, probably because of the presence of cubanite and the large difference in the concentrate grades feeding the circuits."

Jan 1, 1995

By M. C. Leverett

The behavior of mixtures of immiscible liquids in porous solids is of rapidly increasing interest to those engaged in the production of petroleum. The operation of artificial water-floods and the control of natural ones immediately raise questions concerning the fundamental nature of such processes. Moreover, it is now recognized that often water occurs dispersed throughout the rock from which the oil issues into the well,' and thus tends to move toward the well simultaneously with the oil. The work reported here is a laboratory investigation of the simultaneous, steady-state flow of oil and water through the same column of uncon-solidated sand. It is thus directly related to the situation in which water occurs in oil-producing sands; it may have less direct implications for the displacement of oil from sands by water. However, it is to be clearly understood that the experiments to be described were performed primarily to obtain information of a more or less fundamental nature, and are not an attempt to reproduce, on laboratory scale, any part of an oil field. The dynamic behavior of a system in which oil and water are flowing simultaneously through sand is best described in terms of its "effective permeability" to either phase. For incompressible fluids flowing through a system of uniform cross section, the effective permeabilities to the two phases, in darcys, may be defined by the equations: Ko = PA6A [la] and Ku = Q [lb] In order to put the results obtained on a comparable basis for different sands, the effective permeabilities will be stated as fractions of the normal permeability of the sand; i.e., fractions of its permeability to a homogeneous fluid. Algebraically, these fractions are: KO' = Ko/K, and KWr = K,/X [2a] and [Zb]

Jan 1, 1939

Solar Salt, Lunar Ambitions I Bauerti The title of this paper is `Solar Salt, Lunar Ambitions'. It is largely the result of a lack of imagination and a tight deadline. I was seeking a catchy title to convey the image of being 'here' and wanting to get `there', with `there' being a long way away and our being held 'here' by powerful gravitational forces. I tried `Solar Salt, Lunar Landings', but that implied we had already reached `there' when, on reflection, we had not. A colleague suggested 'Solar Salt, Luna Park' which is a fun park in Sydney and, I must admit, there was appeal in the image of having embarked on a wild roller coaster ride with stomach-wrenching twists and turns and the only reward being a pair of sweaty palms, and a feeling of nausea. That's sometimes how it feels when you launch into change. In the end I settled for the more sedate `Lunar Ambitions'. It contained that suggestion of hope and continual striving which are central to the idea of best practice. I will discuss our experiences in this area shortly, but I would firstly like to provide some background to our business. The salt industry is steeped in history and tradition. As one learned commentator observed, common salt is 'a substance seemingly too ordinary to think about, yet it is the oldest of man's raw materials and the basis of some of his newest inventions' (Multhauf, 1978). From ancient times, salt was recognised as a key necessity of life and it has played a role in the rise and fall of governments throughout history. The Romans recognised its importance when they gave their soldiers money regularly to purchase salt, hence our modern word 'salary'. Today, while culinary use remains important, the main consumer of salt is the chemical industry (Figure 1).

Jan 1, 1995