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The additional information that Clarke and Taylor (1982) provide about the important but poorly documented Ardlethan deposit is, of course, very welcome. However their contention that structural considerations, in conjunction with petrology, alter the interpretation of the mineralogical and geochemical data presented previously (Scott, 1981) is not accompanied by adequate supporting evidence. Indeed characteristics of the orebodies studied invalidate their arguments.Heterogeneity between matrix and fragments is not a problem in the South Cherry and Ardwest orebodies because most samples are comprised entirely of interlocking hydrothermal assemblages with a fabric and mineralogy that is uniform through both former breccia fragments and matrix. In hand specimen, the rock superficially resembles altered granite and, as indicated by Clarke and Taylor (1982), a brecciated texture is difficult to discern. In thin section, relict brecciated textures can be observed as localized changes in the grainsize or in the distribution of minerals that outline former breccia fragments (P. J. Eadington, 1982, personal communication).Because of the intense brecciation and comminution of rocks (fragments < 10 mm are usual) in the South Cherry and Ardwest breccia bodies, hydrothermal recrystallization was complete, resulting in homogenization of fragments and matrix. Furthermore, the amount of sample analysed (-100 g for drill core and 2-3 kg for hand specimens) is sufficiently large to be representative of both former breccia fragments and matrix. The Carpathia and Stackpool orebodies, with their abundance of sedimentary fragments, have alteration superimposed on a heterogeneous fabric, and were not studied. Thus the problems of differentiating between fragments and matrix (Clarke and Taylor, 1982) are irrelevant to the particular orebodies described in my paper.Within the alteration halo, which is several hundred metres wide (Paterson, 1976), the very uniformity of the alteration assemblages implies that subsequent, postmineralization brecciation is of only minor significance.Indeed tourmaline pipes in the Ardwest pit are less than several metres across (Clarke, 1979) and produce minimal alteration in the surrounding rocks. Therefore the interpretation of the mineralogical zonation is not compromised by the recognition of several periods of brecciation.

Jan 1, 1982

By James Douglas

THOUGH liberality is not supposed to be a prominent trait of the Scottish character, Canada owes to a Scotchman, Sir Wm. Macdonald, more than to any other of its people, not only wise ideas, but pecuniary help towards extending education: and another Scotchman, in New York, has sumptuously housed under one roof three branches of the engineering fraternity, of which we are one. Having thus created us members of the same family-for the metaphorical meaning of house and kinship is identical-Mr. Carnegie expresses more emphatically than even he could in words, that, by affording facilities for closest intercourse, he in¬vites the mechanical, electrical and mining engineers to par¬ticipate in the freest interchange of idea and experience, and to correlate and combine the results of their studies and activi¬ties; and, being members of the same household, to banish re¬serve and secrecy. And now we, the members of the - American Institute of Mining Engineers, meet as though we were at home in a neighboring country. For whether we meet in Canada, in England, or elsewhere, the Institute is always received as though no political or geographical divisions separated its members from those of congenial associations in the land of its host. In truth, the title which we have assumed claims for the sphere of our activities the whole American continent, regardless of such trifling details as boundary-lines. The fact that we meet to communicate each other's experience, to discuss our difficulties, and to seek each other's aid in solving the intricate problems that so often present themselves in the course of our profes¬sional life, is an acknowledgment of our individual helpless¬ness; and therefore an argument for united effort. But no effort can be of any value if there is an underlying suspicion

Jan 9, 1907

By LUKE O. LINDOE

A major clay products industry in the Medicine Hat area since before 1910 has maintained a continued interest in the clays of the Cypress Hills. For the first forty years the materials used were local red-burning Cretaceous and Pleistocene clays and sands and high-quality stoneware clays of the Whitemud Formation at Eastend, Saskatchewan. Recently a much broader spectrum of raw materials has been brought into use. Including the exposures of the Eagle Butte structure, the Cypress Hills present a 1200 m section of clay-like sediments. Of this 1200 m about 94 per cent, the high montmorillonite shales of the Upper Cretaceous, can be considered useless, or nearly so; the remaining six per cent, all fresh-water beds, presents a wide variety of potentially useful materials. The development of these clay resources is complicated by deep surface creep on the south flank of the Cypress Hills, by largescale slumping on the north flank and by a structural complex in the Eagle Butte area.

Jan 1, 1984

By J L. Mauk

Golden Cross is a volcanic-hosted, low-sulfidation, epithermal Au-Ag deposit in the Hauraki Goldfield. Irrespective of the rock type (andesite versus dacite), hydrothermally altered wallrocks are enriched in K, Rb, As and Sb around Au-Ag mineralised veins of the Empire vein system and stockwork. Sodium and Sr are strongly depleted around these veins, whereas Mg and Fe are locally depleted. Calcium and Si display mixed behaviour, varying from unchanged to depleted to enriched. Other elements including Al, Ti, Mn, Zr, Y, and Nb show little change or are immobile during hydrothermal alteration. Element enrichment and depletion trends are directly related to the degree of alteration and the alteration mineralogy. Addition of K and Rb and converse loss of Na and Sr in intensely altered wallrock surrounding veins corresponds to the replacement of igneous plagioclase by hydrothermal adularia. Sodium and Sr occur in moderately altered rocks on the margins or in æhard barsÆ that contain plagioclase. Locally, elevated Si concentrations and depletion of Mg adjacent to the Empire vein system reflects intense silicification of the wallrocks and the replacement of mafic minerals by quartz rather than by chlorite. The geochemical zonation patterns at Golden Cross are very similar to those at the McLaughlin deposit California, and shallow levels of the active Broadlands Ohaaki geothermal system. Therefore, determination of K, Na, Rb, Sr, and Ca enrichment and depletion patterns provides insight into alteration intensity and mineralogy that is complimentary to traditional trace element analysis of As, Sb, Hg, Au, Ag, Zn, and Pb used in the exploration of shallow level (< 500 m) epithermal Au-Ag deposits.

Jan 1, 2000

By Michael Samis

The real option valuation method is often presented as an alternative to the conventional discounted cash flow (DCF) approach because it is able to recognize additional project value due to the presence of management flexibility. However, these two valuation methods can be separated on a more fundamental level by their differences in risk discounting. Real option valuation applies the risk-adjustment to the source of uncertainty in the cash flow while the DCF method adjusts for risk at the aggregate level of net cash flow. This seemingly small difference is the reason why the real option method is able to differentiate between projects according to each project?s unique risk characteristics while the conventional DCF approach cannot. This paper provides an overview of the real options and DCF valuation frameworks and discusses the differences in risk discounting that exist between the two methods. Using grade-school mathematics, this paper clearly demonstrates how, with real options, a unique project risk discount can be calculated which is directly linked to the project?s unique risk profile. It also highlights why the DCF method fails in this regard and shows why a call to ?increase the Risk-Adjusted Discount Rate? is an incomplete solution at best. Finally, a heap-leach project and satellite reserve development project are valued with both techniques and the difference in investment conclusions is explained in terms of the risk-discounting concepts discussed here.

May 1, 2003

The selective placement of coal stripmine overburden is examined. Physical and chemical properties of spoil detrimental to revegetation and groundwater are detailed. The United States is divided into regions or similar problems. Five mining methods already used in the industry, that are capable of selectively handling waste are examined in detail. Technical and economic comparisons are made for the systems when applied to realistic mine settings. The same analysis is conducted for five novel methods capable of selectively handling waste. Comparisons are made between novel and existing methods. Suggestions for new and modified equipment are outlined. Recommendations for further research are provided. This volume contains all Appendices to the report.

Jan 1, 1981

By Yao Zhou

Under the United Nations Convention on the Law of the Sea (UNCLOS), the international seabed area (Area) and its resources are the common heritage of humanity (CHH). Patent rights can be incompatible with the CHH doctrine and its underlying principles because patent holders might charge unjustifiably high prices to license patented technology for exploring and exploiting the Area’s resources (creating a "patent holdup" situation), might choose not to license, or might license exclusively when doing so would contravene CHH principles. However, a reasonable patent licensing regime can contribute to sharing the benefits derived from the Area and promote environmental sustainability. Provisions of the UNCLOS that stipulated compulsory technology and financial transfers were removed in the 1994 Agreement relating to the Implementation of Part XI of the UNCLOS but to promote equity and sustainability I propose a voluntary licensing regime modeled on the concept of reasonable and non-discriminatory patent licensing that has been used in other contexts. The International Seabed Authority or another entity will need to coordinate and promote this licensing regime through governance of intellectual property derived from the Area. This proposed approach can better effectuate the CHH doctrine and its underlying principles.

Sep 1, 2014

By D. Hopkins, D. Türler, R. D. Giauque, W. B. Davis, M. Karaca

In a highly collaborative research and development project with mining and university partners, sensors and data-analysis tools are being developed for rock-mass characterization and real-time measurement of mineral content. Determining mineralogy prior to mucking in an open-pit mine is important for routing the material to the appropriate processing stream. A possible alternative to lab assay of dust and cuttings obtained from drill holes is continuous on-line sampling and real-time x-ray fluorescence (XRF) spectroscopy. Results presented demonstrate that statistical analyses combined with XRF data can be employed to identify minerals and, possibly, different rock types. The objective is to create a detailed three-dimensional mineralogical map in real time that would improve downstream process efficiency.

Jan 1, 2002

By H. Paudyal, K. Ohto, H. Kawakita, S. Alam, B. Pangeni

The orange waste after lime water modification was converted into promising adsorbents for fluoride by metal loading reaction. The effectiveness and mechanism of fluoride adsorption on metal loaded orange waste gel from synthetic and real plating solution were investigated. Amount of zirconium(IV), aluminium(III), cerium(III), lanthanum(III), titanium(IV), vanadium(IV) and tin(IV) loaded on orange waste from aquearegia dissolution were evaluated to be 1.62, 1.16, 0.93, 0.95, 1.20, 1.12, 0.97 mmol/g respectively. The maximum adsorption capacity (qmax) of zirconium(IV), cerium(III), lanthanum(III), iron(III) and aluminium(III) loaded orange waste for fluoride ions were evaluated to be 1.74, 0.91, 1.07, 0.98 and 1.01 mmol/g from aqueous solution. The mechanism of fluoride adsorption by metal loaded orange waste was inferred to be ligand exchange reaction. Application of zirconium(IV) loaded saponified orange juice residue(SOJR) for real plating solution showed effective removal of trace concentration of fluoride down to the accepted standard. The negligible interference of co existing anions like nitrate, carbonate, sulphate and chloride makes zirconium(IV) loaded SOJR a promising sorbent for waste water treatment. The adsorbed fluoride from fluoride loaded zirconium(IV)-SOJR was effectively desorbed by using alkali solution for its regeneration. This work shed light on the potential application of metal loaded SOJR to remediate fluoride contaminated water for environmental relevance.

Jan 1, 2012

By Marlion T. McQuinn

This paper will discuss the design, construction, and performance of the support of excavation on the Dulles East and West Automated People Mover Tunnels and Station projects. The elements of the system included drilled soil nails and rock anchors with reinforced shotcrete to the excavated face. We will discuss the geotechnical characteristics, design and construction considerations, loading criteria, construction techniques, schedule constraints, and performance of the support of excavation system. In consideration of the conference theme, there will be a discussion of the application of the real-time instrumentation monitoring program. The project team worked to design and install approximately 710,000 square feet of shotcrete and 19,000 soil nails/rock anchors as well as excavate over 720,000 cubic yards of rock materials within 15 months and in such a manner as to minimize the disruption to airport passengers and operations.

Jan 1, 2006

By J. -M. Chautru

A geostatistical simulation of a typical mining site for polymetallic nodules in the North Pacific Ocean is presented. This is the first stage in the design of an industrial mining system. Two variables which have a major effect on the orebody's economic potential are considered, namely: the maximum slope of the ground inside a mining block of 50 x 100 m; and the average quantity of nodules on the same support. Two geostatistical problems have emerged in this study. The first is due to the lack of a change of support model for the maximum of a variable. A provisional solution, considering an experimentally accessible 'equivalent' support, is proposed. The second is due to a non-linear link between the two variables. To be able to take this into account in the simulation, we propose a new method based on the decomposition: X = E(X/Y) + Residue (X). Satisfactory results were obtained with this approach.

Jan 1, 1987

By R. Peroni, J. Kopp

Mine planning and scheduling is based on using a geological model for the deposit. Blocks are used to discretize the deposit into mineable volumes where grade values are assigned. Traditional estimation techniques such as kriging or inverse distance weighting are frequently used for this task where an interpolated value is calculated within a discrete volume. This group of block grades is the input for sequence optimizers, which base their decision on the economical value of a given block. Ultimately, the economical value of a block depends on its grade, making mine sequencing sensitive to all estimated values. If one looks to a block not as a single grade but as a set of equally possible grades, its economical value will change as different grades can be assigned to it. Stochastic simulation is known to provide the tools to assess grade variability, which makes it possible to generate equally probable values in a block. Different grade block models can thus be built and multiple sequencing alternatives are observed by running the optimizer for these distinct inputs. The results demonstrate that the methodology is adequate for risk assessment and proves to be useful for mining project sensitivity analyses. Differences in the project net present value showed that there is little difference between the two simulation methodologies (sequential Gaussian simulation and sequential indicator simulation) applied. The process is demonstrated using a Brazilian kaolin deposit. Keywords: geostatistical simulation, mine planning, sequencing, risk assessment, open pit optimization.

Jan 1, 2003

By T. K. Smith

The comments contained in the discussion of the paper concerning the prediction of fracture gradients are of considerable interest, since the subject is of a very controversial and timely nature. It is regrettable and Fairhurst2 contradicts the author's statement in the third paragraph of Other Applications. These references create significant doubt that Eaton's Eq. 1 predicts fracture pressure during the injection of fluid into old wells. 3. No evidence is presented in this paper to support the author's Conclusions 2 and 3. While an empirical coefficient related to back-calculated field data is correlated with depth (Eaton's Fig. 4), there is no reason to suspect that this coefficient might be the Poisson's ratio of the various formations involved. 4. Until the field data supporting the empirical approach proposed by the author are presented and evaluated, the accuracy claimed in Conclusion 5 is without substantiation. References 1. Geertsma, J.: "Problems of Rock Mechanics in Petroleum Production Engineering", Proc., First Intl. Symposium on Rock Mechanics, Lisbon (1966) 585. 2. Haimson, B. and Fairhurst, C.: "Hydraulic Fracturing in Porous-Permeable Materials", I. Pet Tech. (July, 1969) 811-817. that the comments are those of a critic and do not offer an alternative and better method for the prediction of fracture gradients. Nevertheless, a reply is in order.

Jan 1, 1970

By R. Mensah-Biney

The loading characteristics of gold-tetrabromide species onto activated carbon have been evaluated using a completely mixed batch reactor system. The overall loading of gold onto carbon was rapid for the first hour but continued slowly without cessation as a result of reduction of gold. Conventional equilibrium considerations were therefore not applicable. Although loading continued slowly after several days, abnormally high loading capacity values of 10-12 meq/g carbon (650-800 kgAu/tonne) could be attained within 72 hours. The loading of gold-bromo species by activated carbon was by the mass transfer of [AuBr4l-onto the carbon surface where reduction to metallic gold took place. Elution of gold from the loaded carbon was feasible provided the carbon had not been loaded to too high capacity values. If loading is carried to high levels, complete elution becomes impractical and the gold may be recovered by ashing the carbon. For the high loading capacities observed, this option would appear to be cost effective. The effect of several variables on the loading capacity of the activated carbon is discussed.

Jan 1, 1992

By H. R. Manouchehri

"Pyrrhotite (Po) is one of the most abundant sulfide minerals in processing industry and must be rejected in most cases. Particularly, Po rejection and its selectivity against pentlandite (Pn) have long been a challenge due to similarities in the mineral composition of the two minerals and the collectorless flotation characteristics of Po. Xanthates have been widely used to promote sulfide mineral flotation; however, in the presence of xanthates, the redox potential established at the mineral/solution interface is most important, determining the flotation performance. In this paper, the importance of electrochemistry in Po and Pn flotation has been demonstrated and a comprehensive study was conducted on two different feed streams (i.e., magnetic concentrate and scavenger cleaner streams, containing magnetic and nonmagnetic forms of Po, respectively), from Vale’s Clarabelle Mill in Sudbury, Ontario, with an objective to determine if improvements in Po rejection and Pn recovery could be achieved by controlling pulp electrochemistry. By conducting a series of flotation tests under different Eh conditions and reagent usage schemes, it was revealed that higher Po content in the magnetic stream may protect Pn from being oxidized, improving Pn recovery. The results indicated that at low oxidizing pulp chemistry, the rest potential for the Pn is still high enough to allow the formation of dixanthogen to promote its flotation. Using a Pt electrode, it was found that by controlling pulp potential at -50<Eh< +50 mV, the Pn recovery and Po depression would be satisfactory. The results, using mineral electrodes (Outotec Chena analyzer), indicated that selective separation can be achieved if low-to-moderate oxidation potentials (0 to 100 mV) or reduction (0 to -100 mV) potentials are monitored using Pn and Po electrodes. Mixing two streams at 50:50 wt % would be possibly beneficial in selective separation.IntroductionPyrrhotite (Po), Fe1-xS, is one of the most abundant sulfide minerals in the processing industry. It is an iron-deficient sulfide that occurs either in monoclinic or hexagonal form. The monoclinic one is richer in sulfur and is ferromagnetic, whereas the hexagonal Po is poorer in sulfur and has no magnetic properties. In general, the ferromagnetic properties of natural Po increase with increasing sulfur content. Although Po holds significant iron content, it is not used as a feedstock for the iron and steel industry due to the difficulty in achieving complete removal of sulfur. The common availability of iron oxide ores makes the iron sulfides irrelevant for the steel industry."

Jan 1, 2015

By Valentine Chanturiya, Irina Khabarova, Maria Ryazantseva, Igor Bunin

"XPS investigations of the influence of HPEMP - treatment duration on the surface composition for natural chalcopyrite and sphalerite are described. HPEMP is a video pulse with a nanosecond front lasting between 5 and 10 ns. The electrical field component can reach 30 kV, whereas pulses repetition frequency is 100 Hz. In general, the formation of metal-deficient surfaces, polysulphides or elemental sulphur and oxides/hydroxides, were determined during the treatment for both sulphides as well as the essential differences of the way of mineral surface transformation during the treatment. The chalcopyrite surface shows the formation of elemental sulphur under the HPEMP treatment at 103 pulses while appearance of unstable sulphite species was detected at the chalcopyrite surface within 5 seconds (0.5•103 pulses) under the same treatment conditions. The results indicate that the quantity of adsorbed water (at.%) is changed considerably during the HPEM - treatment depending on treatment duration for both minerals. The concentration of water onto the chalcopyrite surface decreased during 30 seconds (3•103 pulses) of the HPEMP - treatment and it rose after the treatment at 5•103 pulses. The inverse dependency was obtained for sphalerite surface. Single mineral flotation tests have shown the significant increasing of the minerals recovery."

Jan 1, 2014

By Arthur S. Cornford

According to Arbiter (Reference 1), the ball mill was invented by Brückner in Germany in 1876 and was first used in the United States on ores about 1905. The basic concept was a simple rotating cylindrical drum in which the tumbling action of the charge of material and grinding media resulted in size reduction of the material. Despite the very low mechanical efficiency of this method a number of factors have caused the tumbling mill to remain, by far, the most widely used piece of equipment for mineral grinding. The principal factors influencing this situation have been simplicity of design, ease of manufacture, ready adaptability to familiar material handling layouts and the absence of practical alternatives acceptable to the industry. In the early mills, the material was ground in batches, the mills being charged and discharged through doors in the shell. The shell was supported by means of solid trunnion shafts resting in plain bearings and the drive was accomplished through one of these shafts. In some later batch mills, the mill shell was supported on rollers which were also used to drive the mill. At an early stage, continuous operation was made possible by feeding and discharging the mill through hollow trunnions, the method still in most widespread use. The mechanical and structural design of the early mills was not an onerous engineering task. Norse sense and good practical knowledge were key qualifications. The mill shells had to be heavy enough to withstand the physical abuse they would receive in the field and the bearings had to have low enough unit pressures and sufficient wear retol to ensure several months of operation before the need for replacement occurred. When these requirements were satisfied, stresses developed in the equipment during operation were insignificant and the majority of structural failures were probably due to the use of inferior materials in manufacture. Over the years, the ever present demand for increased productivity has resulted in a steady Increase in the size of units of production equipment, including grinding mills. Arguments have been presented elsewhere, for and against the Idea of a high throughput single line grinding operation as opposed

Jan 1, 1972

By P G. Gaylard

The minerals Industry carries out over US$ 2 billion of R&D annually. The R&D is performed at three levels ? in house research facilities; on a one-on-one basis with a research provider; as syndicated (collaborative) research. The key to a successful R&D programme is project selection. It is suggested that at this time of ?bounty? for the minerals industry the research portfolio should contain some ?blue sky? but potentially long term significantly beneficial projects. This said, the projects should align the technical concepts with the business imperatives. AMIRA has found the ?Road Map? concept has assisted in defining areas for R&D. Examples of this methodology using a Copper Road Map developed by AMIRA for the copper producers operating in South America is presented. The benefits derived from syndicated research are also discussed.

Jan 1, 2007

By Willy Ank de Morais

Pontos estratégicos de solos foram analisados com o objetivo de estudar a possível contaminação de água pluvial, por difusividade, mantidas em reservatórios existentes na Ilha dos Arvoredos, localizada no Guarujá, litoral de São Paulo, Brasil. Iniciou-se o procedimento com a preparação das amostras (homogeneização e quarteamento), seguida das análises físicas (granulometria e umidade). A caracterização foi realizada por espectrometria de fluorescência de Raio-X e por espectrometria de absorção atômica. As concentrações de enxofre foram quantificadas por forno de combustão e as cinzas e matéria volátil por TGA (Analisador Termogravimétrico). As análises realizadas em Raio –X mostraram composição química de solo argiloso com altas concentrações de SiO2 e Al2O3 e as realizadas no equipamento de combustão mostraram concentrações de enxofre menores que 0,03%. Os resultados se apresentaram negativos para metais pesados ou outro tipo de elemento que poderia comprometer a potabilidade das águas contidas nos reservatórios.

Oct 30, 2017

By Ralph Harris, Xia Qi, Frank Komsic

"Gold cyanidation kinetics which are often limited in commercial operations by the rate of oxygen dissolution from gas bubbles into the slurry, are discussed. Emerging technologies for improving the rate of oxygen dissolution are compared and the gas efficiency, energy use and operating performance of inverted cones and a device based on a jet diffuser are examined. The effect of solids loading is also reviewed and a relationship between operating parameters and the kilograms oxygen dissolved per kilowatt-hour is presented.Inverted cones are shown to create slurry settling problems at high gas flow rates and surface tension lowering agents are shown not to greatly improve the overall rates of oxygen dissolution.The novel jet diffuser technology operates at a range of gas to liquid ratios that improves its energy use over conventional technology and the performance of a number of designs are discussed.Gas efficiencies as high as 35% were observed with the novel diffusers at 40 cm diffuser immersion and are expected to increase at greater immersions. Energy use of 1.8 kg 02 I kWh were estimated for prototype full size diffusers operating at 100 cm immersion. Energy use of 3.S kg 02 /kWh is conservatively expected at 600 cm immersion.IntroductionGold ExtractionGold that can not be recovered by gravity separation can be recovered by either the Merrill-Crow process or the newer carbon in pulp (CIP) or carbon in leach (CIL) processes 1. Reductions in operating costs and improvements in gold recovery are central mill operating strategies. The present paper examines the potential for improvement that can be achieved in the gold cyanidation step of gold recovery. This paper introduces a number of emerging technologies and provides a basis for comparison of the performance. It shows that the basis for comparison of a particular technology depends on the type of gold extraction circuit employed and the type of reactants employed."

Jan 1, 1996