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By Q. Dong, S. A. Nightingale

An investigation has been carried out to assess the effects of an applied voltage on the dissolution rate of MgO refractory in a steelmaking like slag. In this study corrosion results obtained from dip tests using a dense direct bonded MgO refractory in a CaO-SiO2-Fe2O3-FeO-MgO slag are presented. These results demonstrate that the application of a voltage across a dense MgO refractory-slag interface can change the rate of refractory dissolution. For the slag composition used and the voltage range tested, it was found that a maximum corrosion rate was obtained at a voltage setting of -0.45V. The results of this investigation have been explained in terms of voltage affects on Marangoni (interfacial tension induced) stirring and its effect on the MgO dissolution reaction that is at least partly controlled by mass transfer in the slag.

Jan 1, 2004

By P. Stantke

Glue, thiourea and chloride are the common reagents which are used in copper electrorefining to achieve fine-grained and smooth copper deposition. While thiourea and chloride are clearly defined chemical substances, glue is a natural product consisting of a mixture of amino acids in different constituent parts. The amino acids are continually degraded in the electrolyte by hydrolysis until they finally become completely inactive. This effect is well-known, largely constant and balanced by the continuous dosing of glue. In contrast, the behaviour of glue in the batch container is not always foreseeable. The glue can become partly or completely inactive by contamination with acid or bacteria, for instance. Usually this is not noticed, and partly or fully inactive glue is added to the electrolyte over a longish period, with the result that the copper growth is significantly impaired. Examples from operational practice show that, with the help of the CollaMat system, partly or fully inactive glue batches can be quickly detected.

Jan 1, 2007

By G. Dörsam, M. Spreij, S. J. Van der Wal, A. P. Schmidt

The transfer of hot metal desulphurising from the torpedo cars to the hot metal ladles at the IJmuiden BOS plant no.2 caused a decrease in ladle lining life from 680 to 470 heats. Changing the desulphurising agent CaC2 for CaO during a trial period, for environmental reasons, led to a further decrease in refractory life. Availability of the ladles became critical and the major reasons for the low life were identified. Solving one of them, temperature, quickly resulted in restoration of the original lives. However, re- introduction of the new desulphurising agent on 50% of the heats again resulted in a decrease, this time from 700 to 550 heats. In order to be prepared for the full introduction of the new agent, thorough investigation of worn linings was conducted, revealing the major (chemical) wear mechanisms. With these findings, a new design for the hot metal ladle is proposed.

Jan 1, 2004

By D. Harris, S. Murugesan, G. Ye, G. Oprea, J. Rigby, T. Troczynski

The spinel-added and in-situ spinel bonded castables have been developed and widely used in steel industry. It is challenging to develop magnesia-based castables for the non-ferrous industry because the temperatures in industrial furnaces are significantly lower than those in the steel industry and therefore the binding systems of these castables must have the capability to develop a ceramic matrix below 1300°C. It is also challenging to develop a good binding system without addition of fume silica, because the hydration of magnesia may take place during installation, curing and firing of the castables. This work presents the experimental results on developing magnesia-based cement-free, silica fume-free refractory castables using hydratable alumina as the hydraulic binder and a spinel phase as the final ceramic binder. In order to activate the sintering and have a ceramic matrix well developed at the relatively low required temperatures, ultrafine aluminas, chromia, magnesium-aluminate spinel and aluminum titanate powders were used as components of the binding system.

Jan 1, 2004

By J. Starkey

A comminution circuit in recent history, is one of the most difficult parts of a mineral processing plant to design with confidence. It is usually the most costly part of a plant to build, and it can consume up to half or more of the energy used on a mine site. To suggest that comminution energy usage is sustainable in the long term is not possible at this time. What we have to choose from today, based on more than 50 years of experience, does include the best available technology, and the best way to design it. There is controversy in the industry as to how to properly approach the subject of comminution design, with many of the optional solutions requiring a level of training and expertise beyond the ability of a non-specialist engineer. Semi-autogenous grinding technology in particular, has not been properly appreciated because of many recent mistakes in its application and design, which have blurred the positive perception about what SAG technology is, how it can be used, and how it needs to be designed and built. In order to change this, mine owners and senior managers need to take responsibility for, and learn to understand the fundamental challenges that a comminution circuit poses to the project, to the design process, to the operators who use the equipment, and to the resulting metallurgy. This address is intended to summarize these challenges and offer fundamental engineering solutions, which are clear, specific and in a format which is directly applicable to the mining and mineral engineering community.

Jan 1, 2018

By Larry M. Southwick

Processing of ores to recover metals usually generates large amounts of waste materials, such as rejects from concentrating operations, tailings from leaching and slags from smelting. These wastes often contain substantial amounts of iron and other metals, recovery of which are often considered to be of commercial value. Earlier versions of this paper investigated a number of processes built to recover iron from a variety of copper processing residues. This paper will extend that coverage to residues from nickel/cobalt, aluminum, asbestos and oil shale processing and coal plant fly ash. Products of interest are iron, ferroalloys, magnesium and aluminum. While none of these processes achieved long-term commercial success, their efforts cover the gamut of problems that must be addressed in treating dirty and difficult materials to recover generally low-value products. An Adept is an alchemist who can create a Philosopher's Stone, which could transmute base metals into gold. In 1701 in Berlin one Johann-Freidrich Böttger, a nineteen year old apothecary's apprentice, told King Frederick I that he could discover how to make the Stone. He failed and fled Frederick's wrath to Poland. He failed again, and King Augustus II threw him in jail. Then, in 1709, he discovered instead the secret of making Dresden china, certainly a more practical search. His failures in alchemy led to the nickname Adeptus Ineptus.

Jan 1, 2004

By K. Morikawa, K. Asano, J. Yoshitomi

The quality requirements for ladle shrouds have become stricter year by year to the pursuit of higher productivity and improved quality in the continuous casting of steel. The ladle shrouds must be sufficiently durable under severe conditions, such as operation without preheating and during several sequential castings. The consideration is that ceramic fibres, which have been applied in shrouds for thermal insulation during casting, could pose a risk to the worker's health. We realized materials for the ladle shrouds which show high strength and low elasticity. At the same time pursuing effective insulation, a coating which contains no fibres (Foaming Coat) has been developed, replacing the conventional one containing fibres. These materials are durable under conditions of repetitive use and consequently satisfy the customer's demands. The ladle shrouds which were improved in this way have achieved an excellent durable life in hot service of three times that of conventional ones. This paper reports the recent technological developments in ladle shrouds as well as their performance under hot operating conditions.

Jan 1, 2004

By T. Cutard, E. Yeugo Fogaing, C. Gault, H. Marzagui, N. Prompt, M. Huger, C. Deteuf

This paper deals with studies made in the field of the French research network PROMETHEREF. Several refractory castables are considered in this program. In the present paper, one of these materials is considered, it is a low cement castable based on andalusite aggregates. A particular attention is paid to microstructural changes during the first heating and on their effects on the high temperature mechanical behavior. Microstructural evolutions have been characterized by the way of dilatometry, scanning electron microcopy and X-ray diffraction. In-situ observations by environmental scanning electron microscopy gave complementary results on these high temperature microstructural changes. They deal with microcrack formation, phase changes, crystallization, liquid phase formation and sintering. By propagation of ultrasonic waves, high temperature continuous measurements of the Young's modulus have been made. Results confirm the existence of microstructural changes and allow to quantify the Young's modulus variations all along specific thermal cycles. High temperature four point bending tests and room temperature tensile tests were made in the same temperature range. Behavior evolutions could be found and interpreted with the help of previously mentioned results.

Jan 1, 2004

By Mauricio Olivares

About Largest combined Phosphate and Potash company in the world Corporate headquarters in Plymouth, Minnesota Publicly traded on NYSE under MOS

Aug 1, 2013

By Michel Aubertin

Mining activities can produce large volumes of waste rock, which are typically deposited in piles on the soil surface, above the water table. Such piles can cover areas of several tens of hectares and can reach over a hundred meters in height. For hard rock mines, the waste rock grain size can vary from silty particles to metre-scale blocks. The internal structure of a pile constructed on a relatively flat surface typically includes two main zones. The first zone corresponds to the heart of the pile, and is formed by several sub-horizontal stratifications (with dense and loose layers) due to the heavy mine equipment traffic which induces local compaction and degradation of the waste rock. The second zone corresponds to regions where waste rocks are deposited by push-dumping or end-dumping close to the external flank of the pile, inducing grain size segregation along the slope. Depending on the deposition sequence, grain size distribution and bench height, a gradation may then be observed, with coarser particles (with cobbles and blocks) near the base and finer particles near the crest, together with inclined stratifications due to the advance of the deposition face. These internal features affect the distribution and flow of water (and air) in the pile. To assess the internal distribution of material properties within the pile, a combination of several tools is usually required which can provide information on the hydrogeological and geochemical characteristics of the waste rock. In this regard, geophysical tools are very interesting because they can lead to a threedimensional mapping of property variations. The information gathered from a combination of appropriately selected techniques can be used to construct numerical models to further study unsaturated water flow and reactive transport. Such simulations help better understand the pile response in its actual and future states, which in turn provides input to adjust the deposition sequence, to plan for closure, and to select an in situ groundwater monitoring strategy. The presentation will give an overview of techniques that have been developed to characterise material properties in the laboratory and in the field, and to obtain a general picture of a pile?s internal structure. Additional results on unsaturated reactive transport modelling will also be shown to illustrate how the internal pile structure may influence its hydro-geochemical and environmental response.

Nov 1, 2008

By H. Henein

Atomization provides many advantages in processing such as rapid solidification and near net shaping. Two atomization techniques will be compared and contrasted in this presentation: Single fluid atomization techniques such as Impulse Atomization (IA) and gas atomization. The characteristics of both processing approaches will be presented. Results in powder structure, size and size distribution as well as microstructure will be discussed. A comparison of spray formed ingots carried out using both techniques will also be presented.

Jan 1, 2007

By Jacek Paraszczak

As the deposits located closer to the surface are getting depleted, more and more Canadian mines produce ore from considerable depths. Deep mining represents a number of serious challenges including high rock temperature. Conventional diesel powered loadhaul- dump machines and trucks so widely used in metal mines constitute an additional source of heat and noxious gases. Due to this, they have a substantial adverse impact on a quantity of fresh air required and a cost of ventilation, particularly since the mines have to meet more and more stringent regulations in this respect. In this context, the paper examines possible alternatives for diesel powered equipment, both these commercially available as those at the stages of prototypes or under development. They are reviewed with regards to their principles, required infrastructure, stage of technology development and its progress. The questions of their flexibility, practicality and economic viability are also addressed. Following the above a potential for their implementation and possible benefits (if any) in the conditions of deep Canadian mines is discussed. The paper concludes with short to medium term predictions concerning the most promising drive alternatives for vehicles destined to operate in deep metal mines.

Feb 1, 2008

"“Developed by the CIM Sub-Committee, these guidelines are an addition to Guidelines Specific to Particular Commodities which are appended to the CIM Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines.Rock Hosted DiamondsJennifer Burgess, Consultant, Sechelt, BCNeil Buxton, WWW International Diamond Consultants Ltd.Darren Dyck, BHP Billiton Diamonds Inc., Kelowna, BCMartinus Oosterveld, (De Beers retired), Plettenberg Bay, South AfricaRichard Routledge, Scott Wilson Roscoe Postle Associates Inc., Toronto, ONMalcom Thurston, De Beers Canada, Toronto, ONPreambleDiamonds are produced commercially from intrusive rock, consisting of kimberlite and lamproite, and from alluvial and marine placer deposits. These guidelines apply to rock deposits; the term ""diamonds"" herein refers to natural diamonds; ""diamond deposits"" refers to diamonds hosted in kimberlite and lamproite rocks; and ""diamonds"" and ""stones"" are interchangeable.The CIM Best Practices General Guidelines for other commodities are also applicable to diamond deposits, however, because of diamond's distinguishing aspects, additional guidelines are appropriate as published in the CIM Guidelines for the Reporting of Diamond Exploration Results and these Best Practice Guidelines for estimating Mineral Resources and Mineral Reserves (MRMR).Diamonds differ from other minerals. Firstly, they occur as discrete particles in concentrations as low as parts per billion. Secondly, the release of diamonds from the kimberlite or lamproite host rock is a function of the excavation and treatment process. Thirdly, the value of diamonds varies from deposit to deposit and varies with stone size within a given deposit. These aspects must be considered when sampling, evaluating the resource and establishing the reserve of a depositThe product from metallic mineral mines is generally quite liquid in terms of number of potential buyers, and the commodity prices and price structure are published daily. In contrast, most diamonds are valued in the overall market context only 10 times a year in ""sights"" and the marketing of diamonds is dominated by a small number of organizations. Diamond valuation is more akin to industrial minerals valuation in that process recovery is important at the ""assay stage"", the impact on price of new goods arriving on the market must be evaluated, and product quality must be acceptable to potential buyers."

Jan 1, 2003

The copper electrodeposition from sulphuric acid electrolytes in the presence of Thiourea and Gelatin as additives was investigated by electrochemical noise and cyclic voltammetry in conjunction with the scanning electron microscopy technique. This study was oriented to examine the utility of using electrochemical noise "EN" technique to characterize the electrowinning process and the deposit structure morphology as compared to cyclic cyclovoltammetry "CV", an electrochemical method generally used industrially. Both EN and CV techniques were successful to reveal the effect of different concentrations of Thiourea and Gelatin on copper electrodeposition process. In this study, CV has detected an excess of Thiourea leading to porous deposit. While, the electrochemical noise analysis in the time domain (skewness and kurtosis parameters) as detected the presence of nodules and has given useful information concerning the morphology of the deposit closely related to the macroscopic and microscopic studies.

Jan 1, 2007

By G. C. Weatherly, D. S. Wilkinson, A. M. Limarga

Competition between stress generation and relaxation mechanisms during the oxidation process has been observed. However, the nature of the intrinsic growth stress in thermally grown scales is not well understood. In this talk, we will propose a conceptual model to calculate the intrinsic growth stress based on the analysis of stress-driven diffusional process of oxygen ions along the oxide grain boundary. The calculated stress, which is considered to originate from the constrained lateral expansion of the oxide, is in agreement with a range of experimental observations.

Jan 1, 2004

By D. Kim

Kennecott operates one of the largest and most modern copper refineries in the world at Magna, Utah, USA. The inputs to the refinery are anodes produced at Kennecott Smelter, which has extremely high contents of lead and bismuth. In order to minimize undesired effects in the electrolytic refining process, unwanted impurities, especially bismuth, must be controlled. This paper describes the process development of practicing state-of-the-art quality control and presents the pilot test results of using the MRT Technology for Bi production.

Jan 1, 2007

By Deborah McCombe

"and Bill Roscoe, Consulting Geologist and Principal with Scott Wilson Roscoe Postle AssociatesMineral property valuations are carried out for a variety of reasons, such as mergers and acquisitions, non-arm’s length transactions, initial public offerings of stocks, support of audited financial statements, fairness opinions, determination of vendor considerations, litigation, expropriation, income tax matters and insurance claims.The CIMVal Committee was formed in 1999 to review and advise on approaches to the valuation of mineral properties. CIMVal is a special committee of CIM formed on the recommendation of the Mining Standards Task Force of the Toronto Stock Exchange and the Ontario Securities Commission.After solicitation of views and consultation with various interested parties, the CIMVal Draft Standards and Guidelines for Valuation of Mineral Properties were released for comment in February 2002 and were finalized in February 2003. CIMVal’s objective was for the standards to be used by the mining industry in general and to be adopted by Canadian securities regulators and Canadian stock exchanges. To that end, the standards contain many of the definitions and concepts of National Instrument 43-101, Standards of Disclosure for Mineral Projects, which came into force in February 2001.The intent of the CIMVal Standards and Guidelines is that mineral property valuations be carried out by appropriately qualified individuals and that all relevant information be fully disclosed. It consists of two parts: standards, which are mandatory in the valuation of mineral properties, and guidelines, which elaborate on the standards and provide guidance and recommendations for the valuation process and for reporting."

Jan 1, 2003

By Premil Agarwal, Alok R. Patnaik, Pulak Dhar, Prakash C. Patnaik

In this study, a physics based model has been presented, considering the growth of the thermally grown oxide (TGO) layer on the bond coating of a thermal barrier coating. Using diffusion equations, a model has been developed to physically describe the oxidation process. The mathematical equations representing the diffusion formulations have been solved numerically. The computed results show the depletion of Al in the bond coating as it diffuses both towards the super-alloy substrate and towards the TGO produced in between the bond coating and the ceramic TBC top layer.

Jan 1, 2004

By J. H. Bernard, K. Zak

Abstract- The three traditional types of Variscan vein Pb-Zn-(Ag) mineralization recognized in the Bohemian massif from historic paragenetic studies are confirmed by modern metallogenic studies. Stable C, S, and 0 isotope data, as well as Pb and Sr isotopic ratios of the deposits, indicate a predominantly crustal origin of the constituents in all three types. Although the data also suggest differences in temperature and pressure of formation, and the oxidation conditions and nature of the hydrothermal fluids, nonetheless they are consistent with prevailing metallogenic classifications of the vein mineralization.

Jan 1, 1992

By L. Contretras

This study has as an objective to analyze and to propose actions to improve the quantity and quality of the graduate education in the area of mining industry, specifically of mining engineers, metallurgists, geologists, to satisfy the expectations of professionals in the mining industry. Included are an analysis of the present scenario and the future demands in countries like Chile and proposed plans for the Establishment of Educational Initiatives, country policies and market forecast, vis-a-vis the experience of Australia, South Africa, United Kingdom, Canada and the United States of America.

Jan 1, 2007