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By J. Jara

Oxygen, ozone and air were evaluated in the oxidation of ferrous iron in the presence of hydrochloric acid ranging from 0.1 to 4 M HC1. Stoichiometric coefficients were determined through mass balances of gases and ferrous titration. The molar ratio ferrous to ozone increases from two at 0.1 M HC1 concentration to six at 4 M HC1. For oxygen the same ratio is constant and equal to 2 and it is in agreement with other works. The stoichiometric coefficient of hydrogen ion was not defined due to the effect of hydrolysis of ferrous and in particular ferric ion on measuring acid concentration by titration with sodium hydroxide. Agitation, gas flow and pressure contribute in the utilization of gas. A technique to compare the gas efficiency at several conditions is discussed and it is based on the relationship between oxygen and ferric during time. There is a strong compromise between gas efficiency and ferrous conversion. Oxygen efficiency decreased with time due to ferrous depletion. The gas efficiency ranged from 3 % (low level of agitation) producing 25 g Fe(III)/h to 12 % at 1000 rpm with 60 g Fe(III)/h converted. At 405 kPa absolute the oxygen efficiency was in the range of 80 % producing 300 g Fe(III)/h. The replacement of chlorine with oxygen to enrich molybdenite concentrates by reducing copper to less than 0.2 % was evaluated. Oxygen can be employed in batch or continuous operation and it can treat molybdenite concentrates with high variation of copper content. The dissolution rate is mainly controlled by oxygen addition in which utilization of oxygen plays an important role. Improvement on safety and environmental conditions is feasible by using oxygen instead of chlorine gas. The economics indicate good opportunities to implement oxygen without significant modifications to the actual circuit and enough benefit when oxygen is well used.

Jan 1, 2007

By J. N. De La Vergne, J. S. Redpath

"The authors make recommendations that they believe will improve the efficiency of a mining company's use of a mining contractor's services. The recommendations are in the form of specific ""DO"" or ""DO NOT"" instructions, giving explanations and covering the contracting process from the end of the feasibility study to the end of the job. IntroductionThis paper is an attempt by the authors to set out some of the things which they feel an owner should consider to achieve maximum effectiveness from mining contractors. It is based on our experience as contractors as well as our experience as consultants to owners. Should this paper create the impression that we feel all the responsibility lies with the owner, this is neither our intention nor our belief.Before the Tendering Process BeginsUse Defined EstimatesIn Feasibility Study DO NOT estimate your cost or schedule by telephoning contractors and asking them for ballpark figures. The only kind of estimate that is worth anything is the one that is clearly defined on paper and bears the signature of the author. This type of time or cost estimate takes time to prepare. In general, the estimate will be worth what you pay for it.Ensure Adequate FinancingDO NOT ask contractors to tender on a project unless the funds have been approved for it. Remember that, depending on the size of the job, it will cost the contractor from $5,000 to $50,000 to prepare his tender. When financing is not assured, a single contractor should be approached regarding a detailed estimate and he should be paid for it. Contractors should not be expected to finance speculative mining ventures."

Jan 1, 1980

By W. T. Boyes, J. M. Harrison

"Squall Lake Gold Mines, Limited, owns a group of claims at Squall lake, northern Manitoba, about 75 miles east of Flin Flon and 3 to 4 miles north of the Nor-Acme mine at Snow lake. Gold mineralization was discovered in this locality several years prior to 1944, but it was only in that year that a comprehensive examination of the occurrences was begun. Development work to the end of 1946 has been encouraging and the deposits show interesting relations to rock structure.GEOLOGICAL SETTINGThe gold occurs in a sill of biotite-hornblende diorite at or near its contact with gneisses derived from arkosic sediments . In detail, the contact between the diorite and the arkose to the southeast of it is irregular, with interfingering of the two rock types. On the northwest side of the sill, between it and Squall lake, the rock is staurolite schist (see accompanying sketch-map).Several mineralized shear zones are known, of which those shown are the most important. Within the zones, the diorite is silicified and somewhat carbonatized. Fairly coarse arsenopyrite is the chief sulphide mineral in these zones but, locally, they contain also pyrite and pyrrhotite. Where quartz and chlorite are present, rather coarse gold is associated with them. In that part of the main zone where gold assays have been most consistent, the diorite is rich in albite."

Jan 1, 1954

By . A. C. Atenas

Control of arsenic in the Potrerillos' Refinery electrolyte has been obtained by withdrawing a bleed stream of circulating electrolyte and ensuring the ratio of [O]/[As] in the cast anodes is maintained between 0.9 and 1.0. In order to achieve this control the anode oxygen must be adjusted, depending on the arsenic level in the cast anodes. It has been necessary to modify the time of the reduction step in the anode furnace refining process. Control of this ratio has permitted electro refining of anodes with high levels of arsenic, up to 3000 ppm, while minimizing the volume of electrolyte that must be removed for impurity control so as not to affect the copper concentration in the electrolyte. However this control strategy is not useful when the arsenic concentration in the cast anode is too high, because it is limited by the maximum oxygen concentration allowable for a good quality anodic. Costs have been reduced in anode furnace refining because it is no longer necessary to use alkaline flux injection to remove the arsenic in cast anodes.

Jan 1, 2007

By R. V. Kumar, F. Tailoka

In order to use ZnO laden dust as a possible desulphurization reagent, it is important to evaluate thermodynamics of the Zn-O-S system. At temperatures greater than 1450 K, there is an uncertainty in the thermodynamic data for the reaction of zinc with sulfur to form Zinc sulfide. In this work, the standard free energy has been determined using an electrochemical cell: Pt, Mo, MoO2/YSZ/ZnO, ZnS, S02, Pt., between 1198 and 1602 K. AG° varies from -145,880 to -88,100 J (± 2500) , with a phase change to ZnS (g) by sublimation occurring between 1450 and 1460 K. This is supported by thermogravimetric analysis which shows about 80% weight loss in ZnS from 1273 to 1473 K. Feasibility reactions were also performed and confirmed that ZnS (g) is formed when ZnO reacts with FeS (1473 to 1653 K) or with Fe-Csat-S(1473-1673 K). There is therefore potential for the utilization of ZnO laden waste as an additional or alternative reagent for desulfurisation.

Jan 1, 2004

By Andreea Catalina Gluhoi

The oxidation of propylene and methane has been investigated over two series of Au/MOx/Al2O3 and Au/MIOx/MIIOx/Al2O3 catalysts (M, MI, MII =Li, Rb, Mg, Mn, Ce, Zr). Whereas the effect of the presence of MOx or MOI x/MOII x on the oxidation of methane is relatively small, a large enhancement in activity is observed for propylene oxidation. Synergistic effects have been observed by combining ceria or a transition metal oxide (high oxygen storage capacity) with an (earth) alkali metal oxide.

Oct 1, 2003

By Geoffrey C. Streeton

A continual objective of mine operations is to reduce ground control costs without compromising the overall safety or performance of the installed ground support. Any change in the ground support regime must not result in a less secure or safe workplace. The due diligence required to implement a change in rockbolting practice is extensive, particularly when the new bolting system has not been used at any other mining operation. Factors such as yield, shear strength and embedment strength must all be investigated to gain an understanding of how the rockbolt can be expected to perform. This paper also discusses the substantial cost reductions and efficiency gains which can be achieved through the introduction of the Jumbolt rockbolt.

May 1, 2001

By Jucheng Wang

Unplanned open stope dilution is a major cost factor for many mining operations, even though significant advances in empirical and analytical approaches for estimating stope dilution have been made. Many factors that influence hanging wall dilution are still either ignored or assessed in purely subjective terms. Undercutting the stope hanging wall on both the overcut and undercut development are well recognized factors which contribute to hanging wall instability and dilution. In many mines, undercutting the hanging wall breaks the integrity of the rock mass that may form along continuous foliation or bedding planes parallel to the stope hanging wall contact, reducing stability. This undercutting also increases the zone of destressed or relaxed rock that may potentially fall into the open stope as dilution. An approach is introduced for quantifying the effect of undercutting on potential stope dilution. An extensive database of stope case histories has been collected to look at dilution from Hudson Bay Mining and Smelting operations (HBMS) in Flin Flon.

May 1, 2002

By He Zhexiang

The settlement properties of tailings modified by flocculants were investigated at the Shizhuyuan Mine, with the aims to screen for the most effective flocculants and the optimum dosage rates for tailings sedimentation. The settlement rate was used as the indicator of effective tailings sedimentation. Calcareousness and three polyacrylamides (F1, F2 and F3) were selected for settlement property evaluation. The results proved that sole use of calcareousness or any of the polyacrylamides had no apparent effect on the tailings sedimentation, while a remarkable acceleration of sedimentation could be observed with a combined addition of calcareousness and polyacrylamides, among which the addition of polyacrylamide F2 together with calcareousness is the most effective. The optimum dosage rate of F2 and calcareousness is 50g/t and 3kg/t respectively. The density of tailings slurry has an effect on sedimentation at the early settlement stage, with lower density generating quicker initial settlement.

May 1, 2007

By Kimberly M. Curran

The path by which hydrogen supply is provided to any end use application will have a strong effect on the specific economics and price stability for the product supply and the flexibility with which it can be used. The objective of this paper is to present those variables which play a significant role in the selection of the hydrogen production technology, with a particular focus on several typical mining applications. The variables examined include gas requirements in terms of flow-rate and demand profile, overall volumetric consumption, level of interruption tolerable, gas pressure and quality needs. Also examined are the effects of geography in terms of primary energy supply available as well as existing hydrogen sources, developed or not. The role of these factors in the selection of an appropriate supply chain capable of supporting mining applications that use hydrogen as an energy carrier will be illustrated with a typical mining application scenario drawn upon in the form of a case study.

May 1, 2007

By Sheila E. Daniel

"Since 1989, the Mine Environmental Neutral Drainage Program (MEND) has sponsored research into ways of reducing the environmental impact and financial liabilities associated with Acid Mine Drainage from tailings and waste rock. Toward this overall objective, Kilborn was contracted to review the use and applicability of passive treatment systems for acid mine drainage.Experimentation using passive systems to treat acid mine drainage has been ongoing since the early 1980's in North America. Passive treatments are generally considered an attractive alternative to active lime treatment, since they require minimal human involvement, no power, and only seasonal or periodic care and maintenance after establishment. Most attractive is that initial capital cost to implement a passive treatement system is generally low to moderate. Ongoing operating costs are similarly low when compared to active treatment systems.Passive treatment systems currently used, or under investigation to treat acid mine drainage include: anoxic limestone drains, aerobic wetlands, reed bed wetlands, compost wetlands, microbial systems and bioabsorption systems. These wastewater treatment systems utilize the chemical, biological and physical removal processes that occur naturally in the environment to improve wastewater quality, including: oxidation, reduction, coagulation, adsorption, absorption and precipitation; microbial activity; and, gravity aeration and dilution. The rates at which these processes occur determines the loading which can be treated and the effectiveness of the system.The results of our literature review will be summarized, and insight provided into the applicability of passive systems to treat acid mine drainage from Canadian Mines."

Jan 1, 1995

By F. Andrieux

"Extruded aluminum profiles are increasingly used for lightweight vehicle construction. Since fracture strains of aluminum profiles are relatively low, damage modeling is crucial for reliable crash simulation. For aluminum profiles, not only the stress state but also the orientation influenced both the deformation and damage behavior. For the material characterization smooth tensile tests were performed in six orientations, both stress-strain curves and r-values were registered. Moreover notched tensile and shear-tension tests were performed in three directions. Finally punch specimens were tested to investigate biaxial loading. Digital image correlation (DIC) analyses were performed to determine local strain values such as critical values at failure. Numerical investigations were conducted with the strain based damage model GISSMO, which is well suited and widely applied for crash simulation. For a strain based failure model the choice of the deformation model is crucial. Deformation models with increasing complexity were investigated to find the best compromise over all experiments. It was found that there is still a great requirement on development of a material model which describes the orientation dependence of the hardening behavior over all stress states in order to be able to use a strain based failure model reliably.INTRODUCTION Weight reduction is an important step for less energy consumption and as a consequence aluminium is increasingly used in automotive parts. An important field of application is the well-established aluminium extrusion which allows the realisation of quite complex shapes of profiles required for an innovative lightweight design with integrated functions. Typical applications are chassis parts, bumpers, crash elements, air bags, etc. Especially the Al–Mg–Si medium strength alloys of the 6000 series can be easily extruded to form complex profiles and prevail for extrusion. Since fracture strains of aluminum profiles are relatively low, damage modeling is crucial for reliable crash simulation. For aluminum profiles not only the influence of the stress state but also the orientation with respect to the extrusion direction have an influence on both the deformation and damage behavior and need to be characterized. The effect of orientation on deformation behavior has been intensively investigated in the last decades and material models haves been proposed (e.g. Barlat & Lian, 1989; Barlat, Lege, & Brem, 1991; Barlat et al., 2003) to describe accurately anisotropic behavior. However it can be noticed that the parameters of anisotropic material models often rely on the yield stress in different directions, which means that the effect of strain hardening is not automatically accounted for. The accuracy of the models at large deformation is not guaranteed and has to be verified. In contrast to deformation models both the characterisation and the modeling of anisotropic damage behavior are not systematically studied. Isotropic failure models based on a critical strain as function of stress triaxiality (ratio of the hydrostatic stress to von Mises equivalent stress) are widely used for crash application (e.g., Bai & Wierzbicki, 2010; Sun, Andrieux & Feucht, 2009; Sun et al., 2013). The mechanisms of failure are manifold and not fully understood; to develop an anisotropic failure model it is mandatory to also have experimental data in different orientations for loading scenarios other than uniaxial tension, e. g. shear, biaxial tension, which implies an extensive experiment plan. This makes the development of failure models more challenging than deformation models for which it is possible to develop a reasonable anisotropic model using the framework of yield function and calibrate the material parameters based on results of tensile tests in different directions. Moreover the development of deformation and failure models are intricate as the variables governing the damage evolution are predicted by the def"

Jan 1, 2018

Ni and samaria-doped ceria (Ni-SDC) cermet are desirable materials for making a solid oxide fuel cell anode working at intermediate temperature (800°C or lower) due to its good ionic/electronic conductivity at the reduced operating temperature. An advantage of the use of a Ni-SDC anode is the enlargement of the effective reaction zone in the interfacial area between the anode and the electrolyte. As a result of the mixed ionic/electronic conductivity of the anode, the electrode reaction rate is enhanced. Investigations into the properties of the ceria-based anode reveal that the performance of the anode is closely related to its microstructures, which are dependent on the composition and fabrication conditions of the ceramics. In this paper, a method for quantitative characterization and correlation of Ni-SDC cermet microstructures to the performance of an anode is investigated. A series of Ni-SDC anode samples are prepared by screen-printing (SP) and spin-coating (SC) techniques, and different microstructures of the samples are obtained through controlling the SP or SC conditions and the sintering temperature. Individual phases (Ni, SDC and pore) in the tri-phase boundary (TPB) microstructures in the electrode are differentiated and segmented from each other in optical and SEM images based on the differences in refractivity and atomic contrasts among the phases. The geometric properties of the segmented phases are characterized using image analysis methods, so that a quantitative skeleton illustrating the TPB microstructures of the Ni-SDC electrode is obtained. Statistical analysis of the distribution of the three phases in the TPB microstructures is performed and the relationship of the microstructures with the optimum electrode is interpreted in terms of the microstructure analysis data.

Jan 1, 2005

By Y. A. Grinin, M. A. Liamina, V. A. Shumskij, Y. I. Sannikov, M. V. Radashin

"A brief history of the development of the Kivcet flash smelting process is presented. The broad scope of the process with an ability to treat high grade lead sulphide concentrates, as well as oxidized lead-zinc residues, is emphasized. Fine coal in the charge serves two purposes, one as auxiliary fuel and the other as a pre-reductant for ferric iron in residues. Current Kivcet operations incorporate a layer of coke or “coke checker” at the surface of the slag in the reaction shaft that acts as a reducing agent for flame products or slag that flow through it. Details of this invention, are given. IntroductionFor many years, the sinter-blast furnace lead smelting process has been the main internationally accepted method used for the production of primary lead metal. In recent times, this process has been unable to meet legislated environmental restrictions and it became clear in the mid-1960s that a new and cleaner process would have to be developed. The present level of Kivcet performance was developed in three main stages:1. flash smelting natural sulphide lead raw materials with the attached electric furnace for production of lead bullion and crude zinc;2. natural raw material smelting with lead and zinc separation in a “coke filter” or “coke checker” at the surface of the slag in the reaction shaft to produce lead bullion and ZnO-bearing slag that can be fed to conventional slag fuming; and3. processing of oxidized lead-bearing raw materials, such as low grade zinc plant residues, with the production of lead bullion and ZnO-bearing slag periodically directed to slag fuming."

Jan 1, 1998

By Michael Nicol

A quantitative description of hydrometallurgical operations depends primarily on an understanding of the kinetics of the chemical and physical processes that take place in such operations. This paper will review the current status of kinetics in hydrometallurgy in terms primarily of the author’s experience in diverse unit operations. A distinction will be made between the popular use of models based on limited kinetic data and mechanisms which reflect the actual elementary chemical or physical steps involved in an overall process. Several examples will be used to illustrate this distinction. The proliferation of published papers of declining quality has resulted in the bequest to later researchers of outdated and often incorrect conclusions by a process that is often difficult to reverse. Some examples of these mysterious concepts will be examined and hopefully reversed. Finally, several examples will be given that identify significant gaps in our understanding of the kinetics of important processes that remain unresolved.

Jan 1, 2014

By John Oxenford

There are currently two operators producing oil from the surface-mineable portions of Alberta?s oil sands (Syncrude Canada Ltd. and Suncor Inc.) and two other companies are proposing to enter the industry (Albian Sands in 2002 and True North in 2004). Tailings from the two current oil sands plants contain approximately 220 000 tonnes per year of recoverable TiO2 and approximately 80 000 tonnes per year of recoverable zircon. This represents approximately 6% of the world?s TiO 2 consumption and approximately 9% of the world?s zircon production. With the commissioning of plants by Albian Sands and True North, and the announced expansion of plants by Syncrude and Suncor, it is expected that these tonnages could quadruple in the next ten years. All of these operators have at least 50 years of reserves even at these expanded production rates. The occurrence of heavy minerals in Alberta?s oil sands has long been known and is well documented in the literature. There have been a number of attempts to produce market-grade products from this resource and the results of this work have been quite mixed. Typically, researchers have used the normal mineral dressing techniques of the industry and have found the mineral assemblage does not respond to these techniques all that well. This has led to the widelyheld suspicion that there must be some difficult metallurgical problems associated with this resource. There are three main problem areas that have created difficulties for previous researchers: 1) The bitumen coating on the sand grains; 2) Secondary mineralization such as pyrite, siderite and calcite 3) A high proportion of aluminosilicates (approximately 25%) that have the same gravity, electrostatic and magnetic properties as other minerals in the heavy mineral suite. Recent work by Lakefield Research shows that these problems can be largely overcome with some novel approaches. The bitumen can be removed by washing with a solvent in the presence of a demulsifier. The pyrite can be removed by flotation. And the titanium and zircon minerals can be separated by selective flotation followed by conventional electrostatic and magnetic separation.

May 1, 2001

By K. John

"THE most recent estimate of minteable coal reserves in Saskatchewan was made by the Federal Royal Commission on Coal (1944- 6). Saskatchewan was then estimated to have some 24 per cent of the Canadian reserves and two-thirds of this is located in what is called the Souris-Estevan area, which lies in the southeast corner of the Province and border's on the International boundary. It is also estimated that there are some 61/2 million thousand-tons in this area of lignite coal which grades 8,000 B.t.u. or less and has a moisture content ranging from 30 to 33 per cent. Ownership of coal rights in the Province is widely dispersed between the Crown, individuals, and corporations, and a recent survey disclosed that 40 percent of ownership was vested in the Crown and 60 per cent in private individuals and corporations. Coal rights on Crown lands may be leased at an annual rental of $ 1.00 an acre. Under such leases, a royalty of 5 cents a ton is levied on all coal mined. A royalty of 7 cents a ton is levied on coal produced from lands where mineral rights were purchased from the Federal Government prior to the transfer of jurisdiction over natural resources to the Province, in 1931. An annual mineral tax of 50 cents per acre has also been imposed by the Provincial Government on all coals within a defined producing areas."

Jan 1, 1952

By John Starkey

This paper examines 5 years of SAGDesign testing data with particular emphasis on the grinding test results from two recent projects, the Fortune Minerals Limited NICO project, and the Aurora Energy Resources Inc., Michelin deposits, located in the Northwest Territories and in Labrador respectively. The context is to compare these results with the SAGDesign database. The required SAG mill pinion energy for these two ores showed vast differences, even though both ores had similar average Bond Ball Mill Work Index values - about 13 kWh/t each for the two deposits respectively. Bond Rod Mill Work Index values for NICO ranged up to 19.7 kWh/t for the hardest ore, confirming the harder nature of the coarse material. SAG mill pinion energy to grind the NICO cobalt-gold-bismuth-copper ore from F80 152 mm to T80 1.7mm varied from 16 to 35 kWh/t, while for Michelin uranium ore, it varied from 2 to 9 kWh/t. NICO ore is harder than any other material encountered to date using SAGDesign testing. SAG pinion energy is more than double the ball mill pinion energy using a transfer size T80 of 1.7mm and a final grind P80 of 74 microns. For NICO, the ore is ?off the charts? for simulation design techniques because there is no comparable operating SAG mill treating ore that is this macro-competent. For Aurora, the relationship between SAG and ball mill pinion energy is reversed in that the SAG mill requires less than half of the ball mill pinion energy using a transfer size T80 of 1.7mm and a final grind P80 of 90?. Because these discoveries are so important for grinding mill design, their impact will be dealt with in future papers, at the August METSOC Conference in Sudbury, and at the September SME Workshop in Tucson. It has now been concluded that the ratio of SAG pinion energy to Bond Ball Mill Work Index, is valuable data to use in designing a SAG/ball mill grinding circuit, to help choose the power split needed.

May 1, 2009

By S. Kawai

Natural convective flow of the electrolyte solution plays an important role in several electrochemical systems. Copper refining electrolysis is the most important industrial process to produce high purity copper on large scale. Turbulent natural convection develops along vertical plane copper electrodes installed in an unstirred electrolyte accompanying with the electrochemical deposition and dissolution of copper during the electrolysis. It introduces the electrolyte stratification phenomenon. Thus, the electrolyte is circulated in a special way depending on each electrorefining tankhouse. The theoretical discussion is indispensable to understand the coupling phenomenon between the ionic mass transfer rate and the morphological variations of electrodeposited copper. In present study, the mass transfer rate of both Cu2+ and H+ ions as well as the momentum transfer rate is numerically analyzed accompanying with the turbulent natural convection along 1 m high Cu metal electrode surface.

Jan 1, 2007

By G. Morin, G. Marin, M. C. Parr, J. Carignan

"Investment casting offers many advantages for the near net shape production of complex geometries, however, molten titanium reacts with most of the refractories used in investment casting shelling systems, which leads to the formation of an oxygen contaminated surface layer. This layer, called alpha case, is 0.1 to 0.6 millimeters in thickness according to the casting section size and must be removed either by mechanical or chemical milling processes. Alpha case removal processes affect casting tolerances and may contaminate the part intended for medical applications (e.g. embedding of abrasive grit media in the alloy). A shelling system based on an yttria prime slurry has been developed and was found to almost suppress the mold metal reaction. Yttria is an expensive refractory, but slurry life was found acceptable for small castings using a closed container and flow coating process instead of conventional pattern dipping. Alpha case depth has been determined for Ti6Al4V by metallographic techniques and microhardness measurements on different step block casting cross sections. Alumina and yttria second prime stuccos were evaluated in this study. The shelling system minimizes finishing operations in the production of casting for medical applications.INTRODUCTIONTitanium investment castings have been in the commercial market since the beginning of the titanium era in the mid 50’s. Investment casting is a cost effective way to produce complex parts for medical, aerospace and chemical processes applications. Investment casting of titanium is difficult due to the high reactivity of titanium with air and refractories used for shell mold building especially for the face coat. Melting is done under vacuum and no shelling system has been proven effective to suppress the mold-metal reaction yet. The main issue with the mold-metal reaction is the formation of an oxygen enriched zone at the surface of the castings named alpha case (Frueh et al., 1997; Kim, 2002; Saha, 1986). The alpha case is brittle, reduce the fatigue life in service of the parts and must be removed by chemical milling.For industrial purposes, calcia partially stabilized zirconia based slurries have become widely used in titanium investment casting for primary coats due to a combination of limited metal shell reaction. Calcia stabilized zirconia slurries have an acceptable shelf life and offer an interesting production window. Our experience shows that a resulting alpha case depth is 280 micrometers for a casting section of 6.35 mm in thickness is typical with such a shelling system (Morin, 2013)."

Jan 1, 2016