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By A. Perucho, J. P. Harrison, A. Bedi, L. Alejano, L. Lamas, A. Sofianos, A. M. Ferrero, R. Migliazza, R. Olsson, J-F. Mathier

"In 2010, the Eurocode for Geotechnical Design, EN-1997-1:2004 (CEN, 2004), informally known as Eurocode 7 or EC7, became the Reference Design Code (RDC) for geotechnical design – including rock engineering design – within the European Union (EU). EC7 is one standard within the comprehensive Structural Eurocode suite, which as a whole has been also adopted by a number of other countries beyond the EU. EC7 is thus becoming a key design standard for geotechnical engineering worldwide.As part of the Structural Eurocode suite, EC7 requires designs to adhere to the principles of Limit State Design. However, it is not clear that current rock engineering design practice can satisfy this requirement. In addition, evidence is accumulating that EC7 is currently difficult to apply to, and may even be inappropriate for, rock engineering design. These issues may be due to the fact that the development of EC7 to date took place without any formal input from the international rock mechanics and rock engineering community.In early 2011 under the auspices of CEN (Comité Européen de Normalisation / European Committee for Standardisation), EC7 entered a formal period of maintenance which was aimed at improving the applicability and ease-of-use of the Code. This maintenance cycle will conclude in 2020 with the publication of a revised version of EC7.This paper describes a number of critical aspects for rock engineering in the context of EC7, inparticular the following:– the history of the Structural Eurocodes and the concepts they embody;– the nature of Limit State Design and the challenges and opportunities it poses for rock engineering design;– the formal means by which the Structural Eurocode maintenance cycle proceeds;– the plans currently being developed for improving EC7 with regard to rock engineering design and construction;– the unique and vital opportunity for the entire international rock mechanics and rock engineering community to comment on the Code and make suggestions for its improvement."

Jan 1, 2015

By B. Burger, T. Bester, S. Deonarain, L. S. Schultz

"This paper details the process followed to raise drill and equip a 6.1 metre diameter vertical service shaft at Glencore’s Mindola Deeps project in Kitwe, Copperbelt Province, Zambia. The project scope comprises a shaft collar, bulk air intake, a pre-sink to -90 metres and raise drilling the shaft from surface to a final depth of 1,892 metres underground, in four separate lifts of approximately 475 metres each. Equipping of the shaft steelwork, headframe erection and commissioning the shaft for hoisting. In addition, the scope included the development of a decline down from 5430’ level underground to the new shaft position on 6205’ level. This paper will provide some insight into the successes and challenges encountered during execution of the shaft works to date and provide some learnings for future projects of a similar nature. INTRODUCTION The Mindola Mine is situated to the west of the city of Kitwe in the Copperbelt Province of the Republic of Zambia (Figure 1). The mine is owned and operated by Mopani Copper Mines Plc (MCM), whose shareholders are Glencore AG (73.1%), First Quantum (17.9%) and ZCCM Holdings Plc (10%).Productivity at the Mindola mine has been adversely affected because of significant ventilation and ore re-handling challenges, which are caused by the dilapidated infrastructure, and design of the existing vertical and sub vertical shaft system. In the circumstances, it was apparent that it was necessary to sink a new vertical shaft that would increase the volume of fresh air down the mine, improving the underground working environment and the current hoisting restrictions, resulting in an increase in productivity and efficiency. Because there were two existing levels ideally situated and perpendicular to one another and because a third level was in close proximity to that perpendicular and because the mine required a ramp down to shaft bottom in any event, consideration was given to raise drilling the shaft as opposed to using conventional blind sinking methodologies."

Jan 1, 2019

By Yufeng Yao, Robert P. Lowell

Abstract - Conductive heat flow anomalies associated with hydrothermal sulfide mounds on the seafloor have been studied. Sulfide mounds tend to focus conductive heat flow because sulfide minerals have a greater thermal conductivity than country rock. The topography of the mound above the seafloor, however, leads to a reduction of heat flow, particularly near the center of the mound. Because the focusing effect is constant, whereas the topographic effect decreases with distance away from the center, the focusing effect dominates toward the edges of the mound. The magnitude of these effects depends upon the conductivity contrast and the height/radius aspect ratio of the mound. Conductive heat flow anomalies at sulfide mounds also result from fluid circulation within the edifice. For the active and relict mounds at the TAG hydrothermal field, which have an aspect ratio of approximately 0.3 and a conductivity contrast of 3, the heat flux through the center of the mound should be roughly 70% of the background heat flux. The maximum effect of heat flow focusing is to increase the heat flux by about 30% above background. By comparing these effects with conductive heat flow data at TAG, we find that advective processes dominate conductive heat flow at both the active and relict mounds. Advective circulation can also give rise to much larger lateral and vertical temperature gradients than would result from conduction alone.

Jan 1, 1999

By K. Chotruangprasert

This paper explores Global Reporting Initiative (GRI) reporting practices within the mining industry. Specifically, this paper investigates how and why a mining company makes voluntary reporting decisions to include the GRI indicators that may be considered ?negative? to the company?s reputation. Due to the voluntary nature of the GRI Guidelines, a GRI adopter is not legally obligated to report every GRI indicator. Not surprisingly, empirical studies that evaluated the extent to which companies? sustainability reports meet the GRI requirements (Guenther, Hoppe, & Poser, 2006; Morhardt, Baird, & Freeman, 2002; Samy, Odemilin, & Bampton, 2010; Skouloudis, Evangelinos, & Kourmousis, 2009) have found that reporting practices of the companies under their studies are well below the standards reflected in the GRI Guidelines. An influential study by Clarkson et al (2008) uses economic-based and socio-political theories to explain variation in companies? environmental disclosure. They have found that, as predicted by economic-based theory, superior environmental performers disclosed more ?hard? (i.e. verifiable) environmental information. Inferior environmental performers are found to disclose more ?soft? (i.e., not easily verifiable) claims, which is consistent with socio-political theories (Clarkson, Li, Richardson, & Vasvari, 2008). However, this study and the existing literature do not adequately explain why a company may act in a way that cannot be explained by economic-based and socio-political theories, for example, why it would report some negative soft data that it is not required to report. This paper intends to address this literature gap. GRI reporting by a Canadian mining company, which I would like to call ?Company C?, is used as a case study for this paper. Company C was selected for this research because in addition to ?positive? information, its GRI-based sustainability report also includes both hard and soft ?negative? information such as grievances. Research methods include interviewing Company C?s employees who are involved in preparing GRI reports and reviewing documents prepared both by the company and by external parties. I find that integrative social contracts theory (ISCT) offers a valuable explanation to Company C?s reporting practices. From the ISCT perspective, Company C?s management appears to feel that the company is obligated under social contracts to be transparent. Therefore, Company C disclosed both positive and negative social and environmental information to the public because the management appeared to think that it is the right thing to do. At the same time, being transparent about the bad news gave the company an opportunity to conclude that it had done something to avoid future occurrence of the negative incidents. Therefore, I propose that, in addition to the economic and socio-political theories that are more often used in literature, insights from ISCT are instrumental in improving our understanding of the corporate non-financial reporting practices phenomenon.

Aug 1, 2013

By I. A. Menshikh, S. A. Kotov, N. L. Shinkarkin

All the cycle for conversion of natural and reprocessed uranium of ROSATOM’s “TVEL” Fuel Company is concentrated at the Siberian Chemical Plant. Conversion capacities are located on two sites, i.e. the Radiochemical Plant, which refines feedstock, and the Conversion Plant, which produces uranium oxides and uranium hexafluoride. Liquid radioactive waste arising in the process, after pretreatment, is transferred to a dedicated national operator for underground disposal. Environmental strategies pursued by the Fuel Company involve the introduction of process solutions intended to eliminate liquid radioactive waste and convert it into a solid phase. In the 5–7 years coming, work will be performed to refurbish and upgrade conversion facilities of the Siberian Chemical Plant that will principally change its radioactive waste management scheme. This paper describes the current waste management scheme and sets out planned schemes for management of natural and reprocessed uranium waste, which will be implemented in the refurbishment of conversion facilities of the Siberian Chemical Plant. The new technologies for the management of liquid radioactive waste from uranium conversion described in the present paper have an undeniable advantage over the current technology mainly due to significantly less environmental harm.

Jan 1, 2020

By A. Roy MacLean

This paper outlines the changes in modern-day coal mining that have been brought about by the increased cost of labour and the use of new and highly efficient equipment. In the latter category are mentioned the ramp-plate, the Bretby cable carrier, armoured face conveyors and the shearer-loader. Greater productivity and increased safety are emphasized.

Jan 1, 1969

By S. Gheibi, H. S. B. Duzgun, N. Dadashzadeh

It is widely recognized that there are various uncertainties in the analysis of rock slope stability owing to inadequate information for site characterization and inherent variability and measurement errors in geological and corresponding parameters. Therefore, reliability-based approaches that allow the systematic and quantitative treatment of these uncertainties have become a topic of increasing interest in rock slope engineering. There has been extensive reliability analysis of rock slope stability in the literature. However, all of these analyses are based on the First-Order Reliability Method (FORM). The probability of failure of a rock slope in the First-Order Reliability Method is provided by a linear approximation of the failure function. The FORM is most commonly used because it is efficient; its accuracy, however, deteriorates when the nonlinearity of limit-state function increases. A better approximation of the failure function can establish a more accurate value of the probability of failure. The Second-Order Reliability Method (SORM) overcomes this drawback with a cost of lower efficiency in terms of the number of function calls and computation expenses. Despite considerable studies of the application of the SORM in other engineering fields, a few attempts have been made in the slope stability studies. In this study, a recently published Second-Order Reliability Method with First-Order Efficiency (SORM-FOE) is implemented on a selected rock slope in Amasya, Turkey. The SORM-FOE overcomes the low efficiency of the SORM by decreasing the number of function calls. The probability of failure of both FORM and SORM-FOE are obtained and the results are compared. It is shown that, in high value of failure probability, SORM’s do not significantly affect the analysis and design. However, in very low failure probability, the discrepancy between FORM and SORM-FOE becomes pronounced. It is also shown that, where the second order methods are required, the SORM-FOE is more efficient than the conventional curvature fitting methods in terms of computational costs.

Jan 1, 2015

By B. Panton, J. Carvalho, E. T. Brown

"A major consideration in the design of high capacity tiedown anchors for dam, bridge and tower foundations is the tensile resistance of the rock mass to pullout, typically as a result of overturning moments or hydrostatic uplift. Rock mass pullout capacity for installed anchors is developed from the tensile strength and fracture propagation properties of intact rock, the orientation and physical properties of the discontinuities and anchor confinement at depth. The typically assumed, but generally conservative, design approach is to calculate anchor pullout capacity using the dead weight of a uniformly shaped inverted “cone” with an assumed initiation point and breakout angle. In some cases, some tensile or shear strength is considered across the area of the assumed pullout cone, however, these strength estimates are based primarily on based on limited historic testing data, empirical relationships for rock mass strength developed for other applications, and engineering judgement.As an alternative to the current foundation anchor design method, this paper presents a new approach to the rock cone pullout problem using Discrete Fracture Networks (DFN) combined with numerical simulations. The simulations presented in the paper investigate the influence of fractures in a synthetic rock mass on ultimate anchor strength. In addition, the global influence on fracture network statistics on rock mass pullout failure is also discussed and it is contended that some of the aleatory and epistemic uncertainty inherent in the design of rock anchors can be reduced by considering fracture statistics in anchor design."

Jan 1, 2015

By Xian Jian Guo, Lei Li, Hua Wang

The distribution and behavior of As, Pb and Zn elements in the copper smelting process were investigated using thermodynamics. The differences between thermodynamics evaluation and practical smelting processes were analyzed. The main factors affecting the distribution of the elements are oxygen enrichment in blowing, copper matte grade and smelting temperature. In general, the distribution ratio of As, Pb and Zn to off gas increases with the smelting temperature and decreases with oxygen enrichment in blowing. Meanwhile, their distributions in matte decreases and that in slag increases with the increase of copper matte grade. There is some gap in distributions between thermodynamics evaluation and practical smelting processes. INTRODUCTION The copper concentrates usually contain a number of minor elements, the control of which in copper smelting processes is often a key to the quality of the anode copper produced and may also have a bearing on the overall economics of the process (Yang et al., 2017). Knowledge of the thermodynamic properties of the minor elements in slag is very important in the control of the slagging reactions (Takeda Y, Ishiwata & Yazawa, 2007). In addition, the environmental contamination caused by the minor elements associated with copper-bearing ores, such as As, Pb and Zn, has become more and more important (Wang, 2004). Arsenic, lead and antimony, which are all carcinogenic metalloid elements, are usually contained in iron-rich wastes, and theirs emissions are considered to be one of the foremost environmental concerns (Wang, 2004). It is important to elucidate the elements distribution of them in the reducing-matte smelting process. The distributions of As, Pb and Zn elements in the copper smelting process are dependent on many factors, including the temperature, raw material composition, reduction atmosphere, concentration level, and slag chemistry etc. (Chen L Z, Xu X, 2016). Generally, these minor elements mainly distribute in phases of gas, copper matte and slag in the smelting process (Shu, Wang, & Qu, 2016). The arsenic exists mainly in the form of sulfo-arsenides in the copper concentrate, and it will decompose and be oxidized in the smelting process (Chen & Lu, 2016). Part of the products, including AsS, AsO, As2 and As2O3, evaporates into the gaseous state, and some other part enters into slag phase in the form of As2O3 and As2O5 (Wang, Guo, & Tian, 2017). Meanwhile, the As2O3 in the slag phase can also be reduced to metallic As and combine with Cu, S, Fe forming Cu3As2, As2S3 and Fe3As2, and then enter into copper matte. During the copper smelting process, about 50% of zinc enters into slag phase in the form of ZnO and 45% exists in the copper matte in the form of ZnS. Little volatizes into the gas phase. Most lead exists in forms of PbS and PbO in the copper concentrate, and it is mainly distributed in copper matte in the smelting process (Zheng & Lin, 2015).

Jan 1, 2019

By Jose Alberto Gonzalez, Said Sharif Mahboob, Jeffrey L. Shepherd

"During the industrial electrowinning of zinc, uneven growth can cause short-circuits and make the deposits more sensitive to the presence of impurities that can significantly impact current efficiency. To produce levelled zinc deposits, additives such as glue, licorice and sodium silicate are often added to the electrolyte. Even in the presence of additives, uneven zinc growth still takes place because of the combination of hydrodynamic and electrolysis conditions in the cell house. Recent advancements in imaging spectroscopy and scaling analysis have opened an avenue to further study the effects of additives on zinc growth morphology. In this study, Atomic Force Microscopy (AFM) and scaling analysis have been used to monitor zinc growth characteristics including roughness, periodicity, aspect ratios and growth mechanisms as a function of electrolyte composition as well as deposition time. Zinc was electrodeposited from an industrial electrolyte containing a host of additives onto an aluminum cathode with a platinum wire serving as the anode. AFM images of the samples were collected to obtain 3D topographical information on which scaling analysis was performed to extract details on root-mean-squared (rms) roughness, periodicity (grain size), aspect ratio of surface features and growth mechanism. This analysis provided information on the mechanism by which the previously mentioned variables can impact short term growth and also provided a prediction of expected growth at long deposition times.INTRODUCTIONElectrowinning is one of the final stages in the industrial production of zinc metal. It is during this process where dissolved zinc ions undergo electro-reduction from an acidic electrolyte onto an aluminum cathode and are later recovered by stripping the zinc metal from the substrate. However, due to the nature of zinc growth as well as the various operating conditions, zinc deposition may occur unevenly, sometimes causing short-circuits that can cause electrode damage and reduced zinc production."

Jan 1, 2016

By Hans Lundberg

The magnetometer which was developed during the war for detecting submarines has proven exceedingly valuable in outlining deep-seated structures in oil exploration, and will be useful also to geologists in outlining regional structural features in the Precambrian. Our magnetometer has been developed to outline local and detail structures. 1 am quite sure that all geophysicists and geologists would agree with me that, in ore prospecting, it is important to obtain as much detailed information as possible. We know that, as we ascend from the ground and get away from the magnetic ore-bearing structures and orebodies, the magnetic intensity decreases rapidly, but, worse than that, we lose the details even faster. Figure l shows two strong, very sharp, magnetic 'highs' over two orebodies which, as our distance increases, rapidly merge into one fairly broad, moderately strong anomaly. If we drilled on this maximum, we would not encounter any of the orebodies. Therefore, we should fly the airborne magnetometer as close to the ground as possible in order to duplicate the results of the magnetic ground surveys. The first chance to accomplish this came with the helicopter, which is an exceedingly maneuverable aircraft. It can be landed in a cleared space not much more than fifty feet square. With floats, it can be landed anywhere, even in a swamp, on thin ice, or on soft snow. It can stand still in the air, hovering over a given point. It can ascend and descend vertically, fly sideways and even backwards, at the will of the pilot. It flies forward at any speed up to l00 miles an hour. The helicopter can be taken to any desired position at a given time. It can fly at any useful altitude from a few feet to several thousand feet above the ground. It can fly very close to the ground with safety. In bare areas, the survey flight may be performed a few feet above the ground. In forested areas, however, the flights, to clear the trees, must be made at l00 to 150 feet. To mark out a certain point, a small parachute-like marker may be draped over a tree or laid on the ground. This can be done from the helicopter without touching the ground.

Jan 1, 1947

By M. Rafieazad, P. Fathi, X. Duan, M. Mohammadi, A. M. Nasiri

"Direct metal laser sintering (DMLS) is a metal additive manufacturing technology that creates highly complex components by fusing metal powder into a solid part. In this study, the impact of surface roughness on corrosion resistivity of AlSi10Mg_200C alloy manufactured through DMLS was investigated. The as-printed DMLS-AlSi10Mg _200C alloy was subjected to various surface finishing processes including grinding and sandblasting. The corrosion performance of the surfaces was then evaluated using potentiodynamic polarization testing and electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl solution to mimic seawater environment. Surface characterization and corrosion morphology of the samples were assessed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) spectroscopy. The results of this study show that the surface finishing process and the resultant surface roughness has a significant impact on the corrosion resistivity of the DMLS-AlSi10Mg_200C alloy in the seawater environment.INTRODUCTION Direct Metal Laser Sintering (DMLS), also known as Selective Laser Melting (SLM) (Sames, List, Pannala, Dehoff, & Babu, 2016), Laser Beam Melting (LBM), or Laser Metal Fusion (LMF) (Herzog, Seyda, Wycisk, & Emmelmann, 2016), is an additive manufacturing process that utilizes a precise, high-power laser to micro-join powdered metals and alloys layer by layer to form almost fully dense and functional components in three dimensions from the 3D computer-aided design (CAD) data. Complex geometries not possible with conventional manufacturing processes can be readily manufactured with high accuracy using the DMLS process with no need to time-consuming tooling."

Jan 1, 2018

By Halet. R. A.

"The Quesabe Mine, owned by Brunston Mines Limited, is a gold deposit in the south central part of Duprat Township, northwestern Quebec, about 10 miles northwest of Noranda.It is one of the few gold mines in Canada developed since World War II. The occurrence of gold in the Quesabe fault structure has been known for many years, but serious exploration did not begin until 1945. By 1949, 15,000 feet of diamond drilling had been completed and a shaft sunk to a depth of 635 feet, with lateral development on the 450 and 600 foot levels. In 1949 and 1950 a new shaft was sunk to 1,050 feet, new levels were established at 800 and 1,000 feet, and ore was mined and shipped to the Noranda smelter. After November 1950 the ore mined was treated in the company's own mill. The grade of ore was marginal under existing economic conditions, and production was suspended in April 1952. The mine produced about 100,000 tons of ore with an average grade of approximately 0.25 ounces of gold per ton.GeologyThe bedrock formations are all Precambrian, and the general geology of the area has been described by W. G. Robinson (1). The rocks in the vicinity of the mine are acidic and basic volcanics of the Keewatin series (andesite, rhyolite, agglomerates, tuffs) invaded by the Flavrian Lake granite stock, and by dykes and irregular masses of intrusive felsite, quartz porphyry, syenite-porphyry, diorite, and lamprophyre.The mine workings are in andesite and felsite, about 2,500 feet west of the western margin of the Flavrian Lake stock.The principal structural feature of the area, from an economic point of view, is the Quesabe fault. This steeply-dipping fault cuts all the rock formations of the area, and has been traced for about 11 miles along a strike of north 65 degrees east from Lake Arnoux in the northeast corner of Dasserat Township to Duprat Lake near the east boundary of Duprat Township."

Jan 1, 1949

By Scott K. Palm, Neil D. Pearson, Jr. Read

"Uncertainty is an important feature of many investments, but it is especially important for mineral properties. Mine properties often entail large investments and fixed commitments. Managers in the mining industry often view price uncertainty as undesirable, due to the possibility that the price of the mined commodity will fall to a level that prevents the firm from recovering its investment and fixed costs. This paper identifies pitfalls in conventional valuation methods and outlines a new approach to valuation based on option pricing theory and dynamic programming. In the process, it identifies generic strategies for organizing mine production in ways that allow the owner to benefit from the uncertainty in mineral prices. IntroductionRisk is pervasive in the mining industry. The operation and maintenance of a mine may involve high, and unavoidable, fixed costs. A mine owner can only begin to recover these fixed costs if the price of the mined commodity is greater than the incremental cost of production. But the prices of many minerals are extremely volatile. The price volatility of copper has been significantly higher than the price volatility of a typical stock, for example. A mine owner cannot be sure that the price of the mineral product will remain high long enough for the firm to recover its capital and fixed costs.Mine owners are able to minimize their losses during periods when the output price is below the incremental cost of production by temporarily closing operations. During these periods they incur only fixed costs. While shut-downs help minimize losses, the y do not help the firm recover its initial investment. If output prices remain low long enough, the fixed costs and original investment may never be recovered. High fixed costs, therefore, lead to substantial downside risk."

Jan 1, 1986

By P. B. Marchant

"Based on laboratory and pilot scale continuous biooxidation of complex sulphide concentrates, commercial processing design and scaleup considerations are discussed. Capital and operating cost estimates for commercial biohydrometallurgical operations are summarized and potential applications of biotechnology are discussed. Biooxidation as an oxidative pretreatment alternative to enhance precious metals extraction from refractory sulphide concentrates in stirred tank reactors has received considerable attention recently due mainly to advances in the practical applicability of the process. Biooxidation of sulphides is certainly not a new process, however, application and control in large scale hydrometallurgical operations to treat refractory sulphides remains conceptual and the limited data available is restricted to relatively small laboratory and pilot scale operations. It is the intent of this paper to indicate scaleup and plant scale process design considerations for commercial bioleach circuits, based on recent operating experiences with laboratory and pilot scale continuous bioleach systems. An indication of the expected range of applications will be presented parameters for optimization will be discussed."

Jan 1, 1986

By C. Bazin, D. Hodouin, M. Ounpuu

Sensors are now available in mineral processing circuits to monitor pulp flowrate and density, as well as ore characteristics and other process variables. The amount of information provided by these instruments is considerable but in many cases poorly exploited. This paper gives the results of the application of time series analysis techniques to signals generated by the sensors installed on an industrial Pb dezincing flotation circuit in New-Brunswick. Autocorrelation and cross correlation functions appear to be interesting tools for a preliminary circuit analysis, however the calibration of single input single output discrete transfer functions using collected sensors signals leads to conflicting results. For this reason a phenomenological approach, based on the kinetic and transport properties of the flotation process, is also considered. It has several advantages over the empirical transfer function modelling but also limitations in its applicability to industrial processes. A combination of the transfer function and kinetic modelling approches appears to be a promising avenue for better process modelling and control.

Jan 1, 1985

By D. O. Tansey

This paper will describe the mechanisms involved in delay blasting and how they are applied with the use of D.S.B. It will examine the control of potential damage resulting from detonations, and show how good fragmentation and efficient recovery of this material blasted can be achieved.

Jan 1, 1979

By X. Zhong

Thermal shock resistant properties of reaction sintered bauxite-based ß -Sialon bonded corundum have been investigated, and the results are compared with those of Al2O3 based counterpart. It is found they all have very good thermal shock resistance. Their residual strength ratios after one thermal shock cycle at ? T=1200°C and A T=1350°C are 61-73% and 53-65% respectively. TSR parameters are calculated based on thermal expansion, modulus of elasticity, and fracture toughness determined. The reasons for improved TSR of these composite materials are discussed.

Jan 1, 2004

By Michael L. Free, Shukla. Abhijeet

The short-circuiting tendency of a copper electrowinning cell (EW) based on the roughness of cathode deposits was investigated with varying parameters such as Cu concentration, guar concentration, current density, and temperature. A bench scale EW cell was set up to produce copper under conditions similar to industrial Cu EW. In addition, a statistical analysis and finite element analysis were performed to analyze the deposited thickness, surface roughness and maximum feature height. Interaction data for the cathode deposits suggest that current density and Cu concentration together affect the roughness of deposit more than the combined effect of guar and temperature. Model predictions of roughness were similar to experimental values. The predicted time to short-circuiting was similar to the measured time. This study provides an industrial relevant baseline against which new operating parameters can be compared.

Jan 1, 2014

By S. M. Bulataovic, D. M. Wyslouzil

"The Martison Lake phosphate-niobium deposit is composed of unconsolidated residuum containing clay and silt-size particles of phosphate, niobium, iron and clay minerals. This paper deals with the laboratory and pilot plant development of the flowsheet and the reagent scheme to treat the Martison Lake ore. The ore, in addition to the complex gangue composition, contained several phosphate minerals including fluorapatite, francolite and florencite. The detailed laboratory and pilot plant evaluation resulted in the development of an effective flowsheet and reagent scheme for the selective flotation of phosphate minerals using a fatty acid circuit, followed by niobium flotation using amine collectors at acid pH. The developed flowsheet included des liming of ore, magnetic separation, and selective P 2 O 5 -Nb 2Os flotation. The main aspects discussed include characterization of the ore, step by step development of flowsheet and evaluation of dfferent modifiers and collectors for P20s and Nb20s flotation.INTRODUCTIONMartison Lake phosphate-niobium ore deposit, located 75 km north of Hearst, Ontario was discovered in the early 70's and has been the subject of extensive technical-economic evaluation in the late 70's and early 80's.The deposit is covered completely by 30 m to 90 m of glacial overburden and is composed entirely of unconso1idated material called residuum, that lies on top of a precambrian age carbonatite intrusive from which the residuum was derived by weathering and natural leaching in situ. The residuum is and irregularly-shaped horizontal lens, 2 km by 3 km in area, and up to 100 m thick, composed mostly of unconsolidated clay and silt-size particles of phosphate, niobium, iron, mica and clay minerals."

Jan 1, 1986