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By R. D. Berkenkotter

Titanium and iron assays obtained from cores of three diamond-drill holes from the Cebolla Creek titaniferous iron deposit were evaluated by statistical techniques to obtain information concerning the mineral characteristics of the deposit and to make a preliminary determination of sampling requirements for the deposit. A range of sample volumes representing sizes from one-sixth NX core 2 feet in length through full NX core 10 feet in length were prepared by split-ting the NX core with a diamond saw and combining pulverized splits. Results indicate the existence of at least two statistical populations having different average grades of iron and titanium. Each has an assay frequency distribution that is not normal but is highly peaked (leptokurtic). Frequency distributions of assays from specific altered zones of the drill holes appear to be normally distributed. Increasing the cross-sectional area of the sample unit to change assay volume did not result in significant changes either in assay values or the resulting frequency distributions of assays. However, when assay volume is increased by increasing sample interval, the shape of the assay frequency distribution changes, and a normal distribution of assays is approached. Positive correlation exists between titanium and iron assays. The degree of correlation, although very significant, is too low to use for prediction purposes. Although the amount of data from three widely separated drill holes is not sufficient to establish an average grade for this large deposit, it indicates a range of expected assay values and provides some information for determining requirements of future sampling for evaluation purposes.

Jan 1, 1963

By Tyler Acorn, Brandon Wilson, Jeff Boisvert

Scenario-level uncertainty is a representation of large-scale differences encountered when considering ultimate mining pits optimized over various subsets of stochastic realizations. Accounting for scenario-level uncertainty allows mine plans to be assessed against several probabilistic subsurface interpretations. Scenario-level uncertainty is found through clustering stochastic geostatistical realizations and optimizing final pits across the realizations in each cluster. Where these pits are geometrically different, plans for each scenario differ. Knowing these differences allows the value of each planning alternative to be assessed based on the value and relative probability of each scenario. These results also facilitate the use of formal decision-making frameworks for planning, leading to optimization that better represents the full statistical characterization of the deposit. An example utilizing this approach evaluates both infrastructure placement and drilling program requirements. In both cases, scenario-level uncertainty improves initial plans by limiting opportunity costs and identifying additional potential.

By Tyler Acorn, Brandon Wilson, Jeff Boisvert

Scenario-level uncertainty is a representation of large-scale differences encountered when considering ultimate mining pits optimized over various subsets of stochastic realizations. Accounting for scenario-level uncertainty allows mine plans to be assessed against several probabilistic subsurface interpretations. Scenario-level uncertainty is found through clustering stochastic geostatistical realizations and optimizing final pits across the realizations in each cluster. Where these pits are geometrically different, plans for each scenario differ. Knowing these differences allows the value of each planning alternative to be assessed based on the value and relative probability of each scenario. These results also facilitate the use of formal decision-making frameworks for planning, leading to optimization that better represents the full statistical characterization of the deposit. An example utilizing this approach evaluates both infrastructure placement and drilling program requirements. In both cases, scenario-level uncertainty improves initial plans by limiting opportunity costs and identifying additional potential.

By K. Blaski

his paper reports an investigation aimed at optimizing the compaction of granulated hard-metal powder for the production of cutting tool inserts. The optimal compaction is that which yields optimal shrinkage during sintering, i.e. minimum porosity in the sintered part. Extensive compaction tests on 23 different hard-metal powders have been carried out and have shown that the ideal ?green density? of a hard-metal compact, i.e. the density after compaction, increases linearly with the apparent density of the powder. On the basis of this result, an equation has been derived, which allows one to predict the optimal shrinkage that a hard-metal compact undergoes during sintering once the following data are known: the required sintered density, the volatile content of the powder and the apparent density of the powder. Since these data are available to the tooling designer, this equation allows one to design tooling for the compaction of hard-metal, which leads to optimal shrinkage

Jan 1, 2007

Despite a long history of production of industrial minerals and rocks, New South Wales still offers significant opportunities for exploration for and development of these minerals. Exploration for opal, sapphires, and zeolites in the State has been particularly encouraged by pioneering geological studies by the Department of Minerals and Energy, which have resulted in the development of important new geological concepts and exploration techniques. Large areas with potential for these minerals have not yet been tested. In the case of sapphires, the studies have identified a new type of deposit which is'the source of most of the sapphires mined from alluvial deposits. Recent price increases for heavy minerals, a re-evaluation of previous exploration in coastal regions, and a recognition of suitable environments in inland New South Wales have stimulated renewed exploration both onshore and offshore and have led to increased production. Significant potential also exists for development of a number of other minerals, including: topaz, which occurs in large, unusual and perhaps unique deposits in northern New South Wales; dimension stone (particularly granite); bentonite; diatomite; and silica for metallurgical use. Potential also exists for development of construction material resources, particularly construction sand, which is in short supply in the Sydney region.

Jan 1, 1989

By A. B. Parsons

Jan 1, 1971

By D O’Dea, B Godel, T Honeyands, G Evans, T Harvey

The pores within iron ore sinter are important for producing a high quality material that is strong and easily reduced. The complementary methods of mercury intrusion porosimetry (MIP) and X-ray computed tomography (CT) were used to characterise the structure of industrial and pilot scales sinters across a wide range of pore sizes (3 nm to 100 µm for MIP and 50 µm to 5 mm for CT). The inhomogeneous nature of sinter and the variation in the measurements make it difficult to compare samples. The generalised additive modelling (GAM) approach, using the open source statistical software package, R, has been applied to highlight where there are peaks in the concentration of pore sizes. Importantly, the shape of the GAM-fitted function and the heights of the peaks show statistically significant differences between samples. For the samples investigated, the GAM-fitted functions for the MIP volume distribution of pore diameters were found to have a common set of distinctive peaks at 0.005, 0.6 and 20 µm. The GAM approach was also applied to the X-ray CT measured pore wall thickness, highlighting a single peak whose position varies between samples. The cause of these distinctive peaks and their implications for sinter quality are discussed. Correlation was found between the volume in peak 1 (0.005 µm) and the concentration of primary hematite. No correlation was found between the pore wall thickness and the strength of the sinter, suggesting the composition of the pore walls may be more important. Future work will focus on small-scale sinters produced under tightly controlled conditions to study sinters with a wider range of quality values.CITATION:Harvey, T, O’Dea, D, Evans, G, Godel, B and Honeyands, T, 2017. Highlighting key features of the pore structure of iron ore sinter using mercury intrusion porosimetry and X-ray computed tomography, in Proceedings Iron Ore 2017, pp 39–48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By L. Flett, S. Woods, C. Deredin

"Following a significant reduction in world Imperial Smelting Furnace (ISF) capacity from 2003 to 2008, a major optimization initiative was successfully carried out on the lead upgrading and bulk (zinclead) flotation circuits in the Brunswick Concentrator.This paper describes the process improvements that have taken place in order to reduce the quantity of bulk concentrate:•,Increase in lead upgrading rougher flotation circuit capacity•,Installation of a closed-circuit bulk regrind utilizing MillPebs and 150 mm Cavex hydrocyclones•,Installation of two additional cleaner flotation stages on the bulk circuit•,Optimization of the manipulated variables in the lead upgrading and bulk circuitsINTRODUCTIONThe Brunswick Mine (Xstrata Zinc Canada) is located near Bathurst, New Brunswick and is one of the world’s largest lead/zinc mines. Milling of ore commenced in 1964 from the No. 12 orebody, with an expansion in 1966 to accommodate ore from the No. 6 open pit mine. The planned closure of the mine will take place at the end of the first quarter in 2013. The ore is a complex massive sulphide, consisting of approximately 20% valuable minerals, 60% pyrite and 20% silicates.A simplified flowsheet for the concentrator is given in Figure 1. The overall flowsheet involves SAG milling, secondary ball milling, selective flotation, and dewatering by thickening, filtering and drying. The complexity of the flowsheet evolves from the requirements for fine grinding and the production of four concentrates: zinc (sphalerite), lead (galena), copper (chalcopyrite) and bulk (sphalerite plus galena).Primary hydrocyclone overflow feeds the copper-lead aerator-roughers for flotation at pH 9.0 with soda ash. Plant xanthate (80-20 sodium isopropyl and potassium amyl) and AP407 are used as collectors in the copper-lead circuit. The rougher concentrate is directed to the copper-lead regrind circuit and the tailings are fed to the secondary grinding circuit. The secondary hydrocyclone overflow from the secondary grinding circuit feeds the copper-lead rougher-scavenger banks. Rougher concentrates are reground to a P80 of 28 µm prior to three stages of copper-lead cleaning. The first stage of cleaning is done in an open circuit with the tail reporting to the cleaner scavenger. The cleaner scavenger concentrate reports to the regrind circuit and the cleaner scavenger tail combines with the rougher/scavenger tail to feed the zinc circuit. The second and third stages of cleaning are performed in closed circuit with the cleaner tail being recycled to the copper-lead regrind circuit. The average final concentrate grades 23% Pb, 3% Cu and 704 g/t Ag, and is fed to the copper separation circuit."

Jan 1, 2013

By J. R. Cole-Baker

An independent technical audit by a consultant is part of the accountability process of publicly owned or publicly quoted companies when raising finance through share issues or loans or the sale of equity, and of banks or development funds when granting loans. Africa is undergoing a renaissance in investment in its mining industry. It is forecast that capital investment, in major mining projects in Africa, will be over US$ 4.4 billion, in the next few years. Most, if not all, of the capital to be raised will require an independent technical audit. The aim of this paper is to assist the management of mining companies seeking finance in appreciating the role of such technical audits. The reasons for such audits, especially to attract international investment, are listed. The role of the audit is explained in assessing the underlying robustness of the company as ?a going concern? and the viability of any ?expansion plans?. Its use is emphasised in establishing the underlying value of the company based on the mine life as supported by the mineral reserves. The independent consultant role is stressed as a representative of the parties in a finance deal who cannot, in practice, carry out their own detailed and specialized technical due diligence. The various components of a typical audit are examined with examples of critical matters which may require resolution. The definitions, which are used commonly in audits, in respect of competence and reserves and resources, as stated by various regulatory bodies, are compared.

Jan 1, 1998

Plant survey data has shown that gold recovery through a specific copper concentrator was significantly lower than copper recovery. Size-by-size analysis revealed that this was due to poor recovery of+75 µm and ?23 µm gold containing particles. In order to further investigate the nature of the gold losses, experiments were conducted at laboratory scale. Gold deportment studies on the laboratory flotation products revealed that coarse gold (+75 µm) reporting to the rougher tailing was predominantly associated with non-sulphide gangue. Further grinding of the plant rougher tailing improved recovery of gold and copper, while not affecting iron recovery, due to improved liberation of gold from non-sulphide gangue in coarse size fractions. EDTA extraction to remove surface contaminants showed a similar improvement for fine, liberated gold flotation.

Jan 1, 2003

By Geoffrey G. Huggins

Discussions are presented of the three phases of the noise reduction program on flight-type coal conveyors. The three phases are identification of noise sources, evaluation of potential noise reduction concepts, and implementation of noise reduction which is intended to reduce conveyor noise to less than 90 dB(A) in the underground mining environment. The major noise sources are impacts of the chain on the tail roller and on the top and bottom decks. A total noise reduction of 11 dB(A) was achieved by using techniques which are applicable to retrofit. These are a vibration isolated tail roller and an isolated wear strip on the return deck. A theoretical model of isolation provided by the isolated tail roller is developed. Appendices are presented which contain information on other potential concepts and additional data generated.

Jan 1, 1976

By Teele Tuuna, Voglers Eesti OÜ

Blasting operations are a strong and important part in any kind of building and mining industry, a shot-firer profession is one of the oldest professions in the civilized world. It still serves an important and ongoing purpose in the modern economy all over the world. Europe, nowadays, values strongly the mobility of workers, the movement of know-how and labor force between different countries inside Europe. There are no borders for most of the everyday professions.

Jan 1, 2018

By Larry A. Cramer

"Three primary drivers are setting the trend for base and precious metal processing . they are: continued low real base metal prices, environmental concerns, and continued high prices for PGM.s. Low base metal prices are increasing the search for economies of scale and company consolidation as well as the development of some hydrometallurgical technologies. Environmental concerns are pushing for continued reductions in SO2 emissions and hydrometallurgical technologies. The high prices for PGM.s are driving major expansions and a focus on minerals processing recoveries and, to a lesser extent, reductions in the refining metal lockup.In nickel, HPAL operations on laterites have failed economically but Inco is still pursuing some alternatives. BHP-Billiton and others are developing bioleaching alternatives for nickel laterites and sulphides.Copper continues to be dominated by the hydrometallurgical and pyrometallurgical debate; new hydrometallurgical developments are being tested at several sites whilst the pyrometallurgists continue to make competitive cost and environmental improvements.Gold processing developments are dominated by the use of improved gravity recovery equipment and by the development of thiosulphate as a more environmentally acceptable lixiviant.PGM processing trends are the use of fine grinding technologies, higher power input flotation cells, and new pyrometallurgical technologies. Hydrometallurgical options for some applications are being sought.OVERVIEW The metals industry has remained under price pressure for some time; low and decreasing real prices for most metals have become an expected scenario. Occasional price spikes give some relief but invariably bring expansions and new entrants into an already oversupplied commodity market, thus leading to the continued price pressure. Technical innovation, economies of scale, and improved work systems are continually sought, so as to improve the competitive position of each individual company in such a climate; however, these developments add to the downward price pressure. In such a situation the application of scarce funds to research and development is a difficult task. Excess funding is not available in tight economic times and yet the main route to higher profits is clearly the application of technical developments to lower the cost of producing a metal commodity. Many technical centers have closed as a cost saving exercise and some have coalesced to obtain economies of scale. The Australian based AMIRA research organisation has grown to serve the R&D part of the market well in Australia and in South Africa by acting as the catalyst to form research partnerships between a number of industry players and as an administrator to direct the funding of research projects towards the various applicable research institutions. AMIRA has developed closer ties to Camiro (Canadian Mining Research Organisation) through the appointment of Camiro.s metallurgical processing research director as AMIRA.s North American based director. AMIRA is continuing discussions with MIRO (Minerals Industry Research Organisation) in regard to a merger, with a report outlining the merger proposal expected in March of 2003. Company focused research centers continue to be effective at Anglo American Research Labs, Teck-Cominco Research, Falconbridge Research center, Inco Research and some others."

Jan 1, 2003

By K Belanger, J. Mclachlan, F. Stober, G. Norval, B. Snider, A. Munsch, T. Koehler, E. Piantino, J. Carlos Queiroz

The project to rebuild the smelting furnaces at the Anglo American - Barro Alto ferronickel smelter, located in Goias, Brasil, was initiated in September 2013. To optimize the capital cost, while maximizing furnace integrity and robustness, a design basis giving flexibility to ore composition variation was developed in order to ensure sustained nameplate production. The resulting capital efficient, fasttracked project execution was accomplished through the creation of an integrated project team of Anglo American and Hatch through FEL 3 and FEL 4 phases of the project. The integrated team addressed the project challenges through a cooperative and versatile approach, created by access to knowledge, experience and systems in both Anglo American and Hatch. The team could operate at an optimized speed of execution, as demonstrated in the FEL 3 and FEL 4 completion durations, as well as efficiently mitigating any risks of increasing cost or delaying schedule by utilizing lessons learned and team knowledge from Anglo American on the original green-field project and Platinum smelters and Hatch on similar reference ferronickel furnace rebuilds. Other critical drivers of project cost minimization and revenue loss/generation (considering production revenue of each furnace) are scheduled durations for construction, commissioning and ramp-up. The integrated team commenced construction, commission and ramp-up planning almost one year in advance of the shutdown and this paper will discuss the strategies developed to reduce risks and optimize the construction schedule to mitigate revenue loss and optimize ramp-up time to sustained operation at nameplate capacity.

Jan 1, 2015

In the late 1970's and early 1980's a considerable number of large scale open pit mines were developed in N.S.W. and Queensland. At the time these mines were planned, the industry was characterised by rising coal prices, rising fuel prices, and a host of other labour and government constraints different to the situation today. Yet some mines have clearly been able to cope with this change much better than others. While one mine may now be expanding and profitable, its neighbour may still be labouring under painful adjustment processes. This paper examines the major reasons for this difference. It suggests more robust criteria for assessment of future projects to reduce their sensitivity to changes outside management control.

Jan 1, 1990

By E. M. Shemang, C. E. Suh, L. Mbinkar, University of Yaounde

"Two iron deposits within the Precambrian mineral belt of Cameroon are described in detail for the first time: the Archean Metzimevin replacement iron deposit enclosed in Fe-enriched itabirite, and the Proterozoic granite-hosted, shear zone-related Mayo Binka magnetite deposit. In the Metzimevin de¬posit, quartz is corroded and microplaty hematite overprints martite-textured hematite. The Mayo Binka massive magnetite veins show evidence of deformation in magnetite (fracturing and microbrecciation) and in overgrowths of specular hematite (mechanical twinning and undulating extinction). The magnetite is partially replaced by hematite (martitization) and goethite. Ores from both deposits have >88% total Fe2O3 and low contents of contaminants such as SiO2, Al2O3, MgO, CaO, P2O5, and TiO2. They are also poor in Cu, Pb, Zn, V, Cr, and Ni. The Metzimevin massive hematite is characterized by an accentuated light rare earth element depletion relative to the Fe-enriched itabirite. It is suggested that the Metzimevin iron deposit is the result of hypogene leaching of gangue minerals from, and further hematitization of, an itabirite protore. Although the genesis of the Mayo Binka massive magnetite is unclear, it is spatially related to Neoproterozoic granitic rocks. The data allow some comparison of these little known, but pot¬entially economic iron deposits, with some of the world’s better investigated deposits, and are useful to the exploration efforts for iron ore currently underway in Cameroon and the Central African subregion.Deux gisements de fer de la ceinture minérale Précambrienne du Cameroun sont ici décrits en détail pour la première fois : le gisement de fer Archéen de Metzimevin formé par remplacement et encaissé par des itabirites enrichies en Fe, et le gisement de magnétite Protérozoïque de Mayo Binka as¬socié au cisaillement dans un granite. Au gisement de Metzimevin, le quartz est corrodé et de l’hématite en microplaquettes se développe au dépends de l’hématite a texture martitique. Les veines de magné¬tite massive de Mayo Binka présentent des évidences de déformation dans la magnétite (fracturation et microbréchification) et dans les surcroissances d’hématite spéculaire (Macles tectoniques et extinction ondulante). La magnétite est partiellement remplacée par l’hématite (martitisation) et par la goethite. Le minerai des deux gisements contient >88% de Fe2O3 total et un faible contenu en contaminants tels que SiO2, Al2O3, MgO, CaO, P2O5, et TiO2. Il est également pauvre en Cu, en Pb, en Zn, en V, en Cr et en Ni. L’hématite massive de Metzimevin est caractérisée par un appauvrissement relatif en terres rares légères relativement à l’itabirite enrichie en Fe. Il est suggéré que le gisement de fer de Metzimevin résulte du les¬sivage hypogène des minéraux de la gangue ainsi que de l’hématitisation poussée d’une préconcentration de fer dans l’itabirite. Bien que la genèse de la magnétite massive de Mayo Binka demeure obscure, elle est spatialement associée aux roches granitiques Néoprotérozoiques. Ces données permettent de comparer ces gisements de fer peu connus et potentiellement économiques avec certains des gisements mondiale¬ment mieux connus, aidant ainsi les efforts d’exploration présentement en cours en Afrique de l’ouest et au Cameroun."

Jan 1, 2008

By A. J. Hynes, Lutes. G. G., Ravenelle. J. -F.

"The Anomaly A area of the Clarence Stream gold deposits in southwestern New Brunswick contains mineralized structures that bear geometrical relationships to regional folding events. The four mineralized zones of Anomaly A (AD, MW, 93, and Murphy) are hosted by turbiditic graywacke, quartzose wacke, siltstone, and argillite sequences of the Kendall Mountain Formation. A regional scale structural analysis reflects at least four deformational events, three of which appear to control the folded geometry of Anomaly A (D2, D3, and D4). F2 and F3 folds are coaxial and are refolded into a dome and basin geometry by F4 folds. The mineralized zones are subparallel to axial surfaces of F2 folds. Structural analysis of a mineralized zone exposed at surface indicates that gold mineralization is hosted by a quartz-vein system that comprises veins generated during both D2 and D3. Threedimensional representations of Anomaly A created using drill-core data and ®GoCAD suggest that the quartz-vein system was emplaced in fault structures during D2 as well as within brecciated dilation zones during D3. Three of the four zones that make up Anomaly A have F2 hinge surfaces that can be linked through a geometry compatible with the style of F3 and F4 folds. The apparent continuity of these three zones indicates the potential for kilometer-scale mineralized structures at Anomaly A. Le secteur de l’Anomalie A du gisement aurifère Clarence Stream contient des zones minéralisées qui montrent des relations géométriques avec les épisodes de déformation régionale. Les quatre zones minéralisées de l’Anomalie A (AD, MW, 93, Murphy) sont comprises dans une séquence turbiditique composée de grauwacke, de wacke quartzitique, de siltstone, et d’argilite appartenant à la Formation de Kendall Mountain. Des quatre épisodes de déformation étudiés par l’entremise de cartographie structurale, trois semblent contrôler la géométrie de l’Anomalie A (D2, D3, et D4). Les plis P2 et P3 sont coaxiaux et sont replissés en dômes et bassins par les plis P4. Les zones minéralisées sont subparallèles aux plans axiaux des plis P2. Une analyse structurale effectuée sur une zone minéralisée exposée à la surface indique que la minéralisation aurifère est localisée dans un système de veines de quartz qui contient des veines générées durant D2 et D3. Des représentations en trois-dimensions créées avec le programme informatique ®GoCAD à partir de données de forages suggèrent que le système de veines est localisé dans des zones de failles D2 ainsi que dans des zones de dilatation associées avec D3. Trois des quatre zones qui forment l’Anomalie A possèdent des plans axiaux P2 qui peuvent être liés par l’entremise d’une géométrie qui respecte le style des plis P3 et P4. La continuité apparente de ces trois zones indique qu’une structure minéralisée pourrait s’étendre sur plusieurs kilomètres dans le secteur de l’Anomalie A."

Jan 1, 2008

By M. P. Hay

"For a model to be successful it must address the concerns and needs of a target audience. Further, the model must demonstrate the same patterns of behaviour as the real system, and need only be complex enough to meet this objective. If the model is too complex it can become unusable to those who need it most.With this in mind, SUPASIM has been developed for the practical metallurgist requiring only laboratory flotation rate data as input. Some 35+ successful plant simulations have been completed since 1985. The approach of SUPASIM is to characterise an ore, organise information in an understandable way and add structure to the complex flotation situation and hence support the metallurgist to interpret the relationship between variables and optimise the flotation process.The paper describes the basis on which the model was developed and sets out to provide an insight into interpreting laboratory flotation kinetics and their physical meaning in a production plant and the influence floatable gangue has on float performance and plant design. A case study illustrates how the ratio of slow floating mineral to gangue can influence circuit design and improve recovery on a plant scale.INTRODUCTIONThere is an enormous amount of useful data in the results of a laboratory scale rate test. Each variable of fraction and rate, for mineral, metal and gangue has a physical meaning in the plant. The link between float kinetics and the plant in respect of recovery, grade, pulp density, pulp flowrate, residence time, number of stages of cleaning and circuit configuration has been established by the author in the process of developing SUPASIM."

Jan 1, 2005

By R. Ramírez, N. Aslin, G. Ríos, T. Bravo, A. R. Almansa

Lacy copper has been an on-going concern at Atlantic Copper for at least 10 years and was first reported to Glencore Technology in mid-2010. Over the past 12 years, many of the plates were replaced due to age and general deterioration however; plate passivation and lacy copper issues have persisted. After analyzing all the possible causes of this phenomena, it was found that the problem is caused by a degradation of stainless steel as a consequence of the deposition of Sb oxides. These deposits act as passivating agents of stainless steel, which reduces the density of copper nuclei, causing defective copper deposit, with low thickness and ductility. After doing several tests for reducing/removing the phenomena, the over-riding factor was found to be the anode-cathode overlap. An adequate overlap eliminates the problem of "lacy copper". This was verified during an eight month trial with anodes extended 2.5cm in length. Longer anode not only avoids the appearance of lacy copper, but also recovers cathodes that already have lacy copper. On the other hand polishing of plates only gives rise to a temporary solution that requires on-going polishing, to avoid the re-appearance of lacy copper. INTRODUCTION The electrolytic copper refinery of Atlantic Copper in Huelva (Spain) was commissioned in 1970 with an initial capacity of 40,000 t of cathodes per year. In 1975 the copper refinery was expanded to 108,000 t/year. From 1994 to 1996, a new expansion together with the implementation of ISA permanent cathode technology led to a capacity of 215,000 t/y. Since 1995, a progressive increase in the current density up to 350 A/m2 has been accomplished, which together with an increase in the number of cells from 1,120 to 1,204, has led to the present cathode production capacity of 290,000 t/y A lack of copper deposition in the lower part of the steel permanent cathodes was first reported in 2010. This phenomenon is known as “Lacy copper” because of the appearance of the copper deposit as it can be seen in Figure 1. The occurrence of this phenomena was relatively low and was assumed to be originated by an excessive anode scrapping. Nevertheless, in December 2015 Lacy Copper was observed in a significant amount of copper cathodes giving rise to the following issues: Increased tramp copper – housekeeping and maintenance problems Poor appearance of cathode deposit and untidy looking bundles

Jan 1, 2019

By Barry Voight

The law [ ] where [ ] is a measurable quantity such as strain and A and cu are empirical constants, describes the behavior of materials in terminal stages of failure under conditions of approximately constant stress and temperature. Applicable to intact rock and rock masses, the relation may be extended to conditions of variable stress and cyclic stress, and may be used to predict time to failure. Applications in rock mechanics include slope and excavation stability and various topics in ground control.

Jan 1, 1989