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By M. Fairman

The effect of welding speed on the microstructure of friction stir processed (FSPed) AZ31B-H24 magnesium alloy was studied using light microscopy, image analysis, and microhardness tests. The grain size of the magnesium alloy was observed to increase after FSP from about 3.5 µm in the base alloy to about 8 µm in the stir zone. The aspect ratio decreased from 1.60 to 1.55 towards the center of the stir zone. The changes in the grain size and shape caused the microhardness of the samples to drop significantly across the FSPed region from 75 HV in the base alloy to below 55 HV in the stir zone. Decreasing the welding speed increased the grain size due to a greater input of heat energy. The faster heating rate due to the lower welding speed caused a deeper penetration of the annealing effects of FSP. It was also observed that the annealing effects caused by FSP were less pronounced with increasing distance from the interface between the sample and pin tool shoulder. The Hall-Petch type relationship of the micro-indentation hardness as a function of the grain size was observed to hold true after FSP.

Jan 1, 2007

By J. R. Perumareddi, V. S. Sastri, M. Elboujdaini

It is well known that high strength steels used in aerospace industry, are generally susceptible to hydrogen embrittlement during surface treatment such as electroplating with zinc on cadmium. Hydrogen embrittlement reduces ductility and results in brittle fracture rather than failure by plastic deformation. Hydrogen embrittlement of high strength steels is mitigated by surface treatment such as plating with other metals. Data on the hydrogen contents of steels before and after surface treatment by hot extraction-thermal conductivity, secondary ion mass spectrometry (SIMS) and UV-visible spectroscopy along with the mechanism are presented.

Jan 1, 2006

By Robert B. Parsons

"Income tax legislation is not keeping pace with federal and provincial environmental legislation. There is a vast array of new environmental regulations at various stages of implementation across the country. Unfortunately, there are serious concerns about the deductibility of significant payments which mining companies will be required to make under these new rules, and the Department of Finance seems to be reluctant to act on these concerns. IntroductionWhile the federal and provincial governments are racing ahead with obvious fervour to introduce new envirorunental laws, the tax rules relating to envirorunental costs are being allowed to lag far behind. In a nutshell, the tax treatment of envirorunental costs is not keeping pace with the new envirorunental legislation.One of the most serious concerns of the mining industry is the deductibility of mine reclamation or closing costs. The producing provinces are well advanced down the road toward mandating upfront deposits, bonds, or similar financial guarantees to protect the envirorunent from the operation and eventual closure of a mine. These requirements are not small. In some instances, they can amount to tens of millions of dollars. And, if there is no tax deduction for these sums when they are set aside by the mining company, then the costs have to be paid out of the company's after-tax earnings."

Jan 1, 1991

By M. Leijd, K. S. Forrester, M. Saxon, M. Oczlon

This paper provides an introduction to wet high intensity magnetic separation (WHIMS) and its successful application to the beneficiation of rare earth element (REE) enriched eudialyte. The analysis includes an in-depth reporting of the deportment of key elements as well as a statistical interpretation of the relative importance of operational parameters including magnetic field intensity, flow velocity, and matrix loading density. Conclusions are drawn on the relative success of the technology, potential areas for process improvement, and the research direction that continues to be investigated. Three original equipment manufacturer (OEM) technologies were subjected to a series of screening and characterization tests to identify the optimal operating parameter set to magnetically beneficiate eudialyte from Norra Kärr, Sweden. Upon the completion of the characterization test it was apparent that the Metso HGMS technology was superior with respect to REE recovery and gangue rejection for the Norra Kärr composite. The Metso HGMS was then subjected to a series of verification tests to confirm the repeatability and reproducibility of the system.

Jan 1, 2014

By Jorge Blanco, Joaquin Gotor, Enrique Delgado, Carlos Frias

Since 2009 Cobre las Cruces (CLC) has successfully operated a sustainable mining business near Seville, Spain, applying the most advanced hydrometallurgical technologies to process secondary copper sulphide ores through atmospheric leaching in ferric sulphate media and using oxygen sparging in a cascade of ten reactors. In comparison to conventional copper smelters, the CLC hydrometallurgical process does not generate SO2 gas, airborne emissions or slags. The copper ore is ground and sent directly to atmospheric leaching reactors; flotation is not required, and consequently, copper extraction is maximized at 93-95%, while producing 72,000 t/y copper cathodes of the highest purity (99.999 wt.% Cu, Grade A). Reserves for the CLC deposit were estimated at 16 million tonnes of ore averaging over 6 wt.% Cu and containing principally a chalcocite mineralization. Other copper bearing species include digenite, covellite, chalcopyrite, bornite and enargite. Pyrite represents over 70 wt.% of the ore. In the CLC leaching process, chalcocite reacts with ferric sulphate at approximately 90 ºC and copper is released into solution while ferric ions are reduced to ferrous ions. The ferric sulphate leachant is regenerated continuously by oxygen injection and consumes sulphuric acid. It is remarked that pyrite plays a crucial role to yield high copper leaching rates. When pyrite is oxidized, a small proportion of iron is co-leached and some sulphuric acid is generated. The CLC leaching technology has been designed to allow a certain level of pyrite oxidation, which is positive in many ways: (i) to maintain a Fe/Cu ratio in solution; (ii) to facilitate Fe(II) oxidation; (iii) to produce a high redox potential; and (iv) to counterbalance a bleed solution that removes some iron. Moreover, galvanic interaction between pyrite (cathode) and chalcocite (anode) can substantially increase atmospheric leaching kinetics and efficiency (copper recovery).

Jan 1, 2016

By A. R. Barnes, R. Pandher, T. Shannon, P. Gover

Following the closure of the Glencore Zinc Brunswick mine, the Glencore Brunswick Smelter has transitioned to treating external feeds, and currently treats a number of secondary Pb-Zn concentrates. Processing these concentrates has in some cases been challenging due to the diverse mineralogy of the feeds. Certain feeds are difficult to ignite or show inadequate sulphur removal during oxidation on the sinter strand, while in other cases, combinations of feeds produce a sinter with unsuitable properties for further handling. This paper discusses two methods developed in collaboration with XPS Consulting & Testwork Services to characterize these feeds prior to processing them and to identify which ones are most likely to pose challenges during processing.

Jan 1, 2014

By R. P. Hackl, P. G. West-Sells

Carbonaceous gold ores are particularly attractive for leaching by ammonium thiosulfate as the gold thiosulfate complex is not significantly adsorbed by the organic carbon present in the ore. A technically and economically feasible process for treating these ores with ammonium thiosulfate has been developed. In this process, gold is extracted by leaching the ore with ammonium thiosulfate, the solution is separated from the ore by counter - current decantation, the gold is recovered by precipitation with ammonium sulfide, and finally the gold containing product is upgraded by reacting the elemental sulfur present in the precipitate with ammonium sulfite. The precipitation filtrate is recycled back to the grinding step to close the solution balance. Reagent consumption is not excessive. Besides precipitating gold, the precipitation step removes most deleterious solution impurities and converts a portion of the polythionates back to thiosulfate. This paper discusses the optimization of the leaching, precipitation, and upgrading steps. The results of a 10 kg/h pilot plant campaign are also discussed.

Jan 1, 2005

By C. -M. Katsari, G. N. Anastassakis

"Copper is considered one of the most important industrial metals because of its properties (conductivity, malleability) and variety of uses. Approximately 70% of the global copper is used for various electrical applications, with a significant part of copper originating from recycling, since copper can be recycled and re-used countless times, without any loss of performance and difference in the quality of recycled copper in comparison to that from ore. Copper recycling significantly contributes to natural resources conservation, waste minimization, energy saving, and overall cost reduction. Approximately, 35% of the globally produced copper originates from recycled copper.The objective of the current work is to investigate the recovery of copper from electric wire scraps using wet shaking table as an alternative to air separation methods that prevail over the wet ones in recycling processes. The tests were carried out using feed of correspondingly high- and low-grade in copper. In the first case, the wire scraps had been subjected to shredding only, prior to tabling separation; in the later, the low-content tailing of prior air separation was used as feed ?n table separation.In regard to testing, the following factors were examined: table tilt, water flow-rate, and reciprocating speed. The results of the tests clearly denote that copper wire separation from plastic polymer is feasible, as in most cases, table separation resulted in heavy products of high purity in copper and high recovery, and tailings of very low copper grade. The results of the current work clearly denote that wet tabling can be applied efficiently for the separation of recycled copper wire from plastic, as an alternative to air separation methods, as well as for the recovery of copper from the low-grade tailings derived from air separation methods."

Jan 1, 2016

By G. Riveros

A new, continuous fire refining process for copper has been developed and tested at the 5 tph pilot scale. During oxidation, the blister copper flows through a packed bed of crushed refractory bricks counter-current to a hot oxygen containing gas. The resulting desulphurized copper flows then directly into a packed bed of charcoal for deoxidation. By controlling the air to natural gas ratio, both temperature and reducing conditions can be controlled. Based on extensive laboratory scale measurements of the rate of copper oxidation and reduction, the process concept was developed aided by process modeling and simulation. The industrial-pilot scale installation built at the ENAMI Paipote smelter in Chile, consists of two cylindrical, compact reactors, operating in line, with a designed capacity of 5 t/h of blister copper. The results of the industrial-pilot tests confirmed the feasibility of the new process. The blister copper processing capacity was increased to 10 t/h with satisfactory sulphur removal. The degree of oxidation as well the copper temperature was controlled with relative ease. The specially designed siphon block allowed for smooth tapping of the oxidized copper and separation of refining slag. The reduction of oxidized copper in the packed bed of charcoal appeared to be very effective while control of the degree of reduction according to the height of the bed ensured control of the oxygen content in the refined copper at the required level.

Jan 1, 2007

By R. J. Grant, D. W. Scott, M. A. Cooper, E. R. Shannon

"The Brunswick No.12 site concentrator processes 10,500 tonnes per day of a complex lead, zinc, copper and silver ore producing four concentrates by differential flotation. Research over the years has led to increased understanding about the mineralogical and flotation characteristics of the ore. A pilot plant study conducted at Lakefield Research, primarily designed to investigate the technical feasibility of semi-autogenous grinding, provided an opportunity to test recent theories about grind size,, reagent schedule and flowsheet configuration.A fundamental approach was taken with each of the unit processes involved in grinding and flotation. Basic operating and metallurgical criteria were established in each area and a step-by-step implementation program initiated in the plant.Significant improvements in metallurgical and financial performance have been realized through the application of basic grinding and flotation principles using conventional milling equipment and without major capital expenditure. Current operating practice is detailed and metallurgical advancements cited.INTRODUCTIONBrunswick Mining and Smelting operates one of the world's largest lead and zinc mines near Bathurst, New Brunswick. Brunswick is a publicly traded company with majority ownership held by Noranda Minerals (63%). In addition to the No. 12 underground mine, the company operates a lead smelter and phosphate fertilizer plant in Belledune, N.B. and maintains a 25% interest in a joint venture with Noranda Minerals' Heath Steele mine near Newcastle, N.B. Through the four operations, a total of 2000 people are directly employed with fixed assets totalling Cdn$187 million (BM&S, 1991)."

Jan 1, 1993

By Robert B. Parsons

"Draft income tax amendments aimed primarily at certain carve-out arrangements prevalent in the oil and gas industry could have devastating results for long standing royally arrangements in the mining industry . Whether or not this potentially damaging effect is intended is largely beside the points-the point is that the mining industry would be well advised to become familiar with the draft amendments and make sure that the potential damage to existing and future royalty agreements is minimized.The draft amendments fail to take into account the nature of mineral royalties and app ear to reflect a lack of understanding of the characteristics of the mining industry.IntroductionOn July 19, 1985 Finance Minister Michael Wilson released draft amendments to the Income Tax Act which are intended 10 effectively thwart the use of so called “carve-out arrangements"".Unfortunately, the proposed amendments are so broad and far- reaching that countless ""innocent"" royalty arrangements in the mining industry, and in the oil and gas industry, are threatened. The potential harshness of the new rules would be compounded by the retroactive application to the amendments to longstanding royalty and similar agreements."

Jan 1, 1985

By Mohammad. M. Khajeh

Rock mechanical properties are important parameters in geomechanical simulation. Considering stochastic heterogeneous models rather than conventional homogeneous layer cake models leads to more realistic simulation results and uncertainty assessment. These heterogeneous models are usually fine scale models generated by geostatistical techniques. Although considering high resolution property models is desirable, geomechanical simulation with a fine scale model is not computationally feasible for full?field, coupled geomechanical-flow simulation. Upscaling of property models is necessary to move from fine scale/high resolution property models to coarser scale/low resolution models appropriate for simulation. Local numerical upscaling was proposed by Khajeh et al. (2012) to describe the macroscopic elastic behavior of complex heterogeneous media and is expanded upon in this work. This numerical technique is not restricted to specific geologies as typical analytical techniques are. Moreover, transversely isotropic deformation is considered rather than the usual assumption of isotropic deformation. To compare the accuracy of the upscaling methodology, in this study shear strain is considered as the geomechanical response of a synthetic facies model and the response of the coarse scale model is compared to other conventional analytical averaging techniques. It is found that the numerical upscaling technique better approximates the geomechanical response of the fine scale model.

Jun 1, 2012

By W. A. Kracht

The McGill Bubble Size Analyzer, with the original image-capturing device (digital video camera), has a proven record for measuring bubble size distributions that are relatively narrow, such as in mechanical cells with frother. However, some problems arise when dealing with bubble size distributions characterized by a bi-modal shape and wide range of sizes such as found in some flotation columns. To measure wide bubble size distributions it is necessary to increase both the resolution to image the small bubbles and the viewing area to include the large bubbles. This can be done using a digital still camera: digital still cameras can have higher resolution than the digital video cameras currently used and with the proper lens the viewing area may be increased without resolution loss. The digital still camera approach was used to measure bubble size distributions in flotation columns at different operations in Chile. A comparison with typical bubble size distributions generated with mechanical cells is presented.

Jan 1, 2007

By Wojciech Naworyta

The development of the Gubin lignite deposit, located in western Poland is the first mining investment of this magnitude in 30 years. Gubin is the second largest prospective lignite deposit in Poland, with over one billion tonnes of indicated reserves, which would be sufficient for a 2700 MW power plant for almost 50 years. The paper presents select problems related to the mining development of Gubin deposit. Attention has been paid to changes in legal and formal requirements for mining investments that were introduced after the change of Polish social and economic system. The significance of spatial, environmental and social conditionings has been emphasized. Typical attributes of the mine planning process have also been presented. Those include the long time horizon of the investment, uncertainty of external conditions and resulting difficulties in the project?s economic evaluation. Focus has been placed on mutual connections between particular elements of the project and time dependence during the process of their development. Iterative characteristics of the design process have been proven, together with resulting necessity of frequent verification of previous assumptions. As a background for presenting selected problems related to future development of Gubin lignite deposit, the methods of design have been discussed ? the variants method, the empirical method and the method of consecutive approximations. The tools and the possibilities of their use for solving specific problems related to mine design of an open pit have been broadly discussed. The chapter in which the authors relate to the specific problems of Gubin deposit development constitutes the main part of the paper. It depicts the assumptions on which the annual production and the total extraction of lignite during life-of-mine period have been based. The process of mine designing has been discussed, taking into consideration environmental, geotechnical, spatial, social and mining conditions. The criteria for choosing the location of the opening cut and the external dump have been mentioned. In the summary, the present state of mine design progress has been presented, together with some problems that will need to be solved during the next stages of the deposit?s development.

Aug 1, 2013

By Y. Kocaefe, D. Bhattacharyay, D. Kocaefe

The carbon anodes used in the electrolytic production of aluminum are made of petroleum coke, recycled anodes and butts, and coal tar pitch. Due to technological advances in the aluminum production technology, aimed at increasing production and decreasing energy consumption and greenhouse gas emissions, better quality anodes are required. Presently, the anode quality is evaluated by visual inspection and the analysis of a small core taken from 1.5-2% of the anodes produced. The visual inspection is susceptible to human error and limited to surface imperfections. The analysis of cores takes time, and therefore, it is difficult to determine the existence of a problem and intervene at the right time. In addition, the core does not represent the whole anode due to the non-homogeneity of anodes. A validated online anode quality control system can highly improve the situation. In this article, an electrical resistivity measurement method developed for this purpose is presented.

Jan 1, 2014

By Tamas Kekesi, Gergo Rimaszeki, Tibor Kulcsar

The efficient purification of soldering waste material can be achieved in a single operational step by the electrolytic refining in pure hydrochloric acid - tin-chloride media. The complex formation of the ionic species may offer a beneficial level of natural inhibition. Using the PCR (periodic current reversal) technology, is efficient in affecting the morphology of the cathodic deposit. In order to optimize the process, the investigation of the solution stability and the electrode reactions is essential. The natural tendency of the Sn(II) oxidation and precipitation can be overcome by properly controlling the concentration of the main components and the ratio of Sn(IV)/Sn(II) in the electrolyte solution. Polarization curves were obtained for different concentrations tin and hydrochloric acid. Conclusions referring to the electrode reaction were derived from the overvoltage - current plots. The morphology of the deposit can be correlated with the exchange current density, also determined from the polarization curves. The cathodic current efficiency and the morphology of deposited metal are affected by the distribution of tin species and the principal electrolysis parameters.

Jan 1, 2011

Concentrator Improvements -1990-1995Back to Basics ?pilot plant versus plant opportunities identified ?understand process fundamentals & baseline -1996-2000Point ?C?Projects ?strategy to improve global competitiveness ?structure implemented to generate & drive ideas ?capital investment for life of mine asset renewal - 2001-200?Six Sigma Methodologies ?emphasis on data, measurements & analyses ?dedicated, highly trained personnel on projects 1990-1995 Improvement Phase??Philosophy??back to basics?approach?understand what each piece equipment needed to do?understand reagents, control variables?confirm operating strategies ??probe, stabilize, institutionalize??test theories, confirm with lab and plant trials?process stability (equipment reliability, controls)?enhanced operator guidelines, operator training?focus on continuous improvement?optimize existing equipment capability?stop looking for ?magic?solutions 1990-1995 Improvement Phase??Technical?finer grind, same equipment?optimize media size/shape to grinding application?balanced available ball mill power to applications?lowered cyclone feed densities where possible?improved selectivity, same equipment?balanced available cells to applications?streamlined process (eliminate process steps)?added cleaning stages where required?understanding pulp/mineral surface chemistry?lowered flotation pulp densities 1990-1995 Improvement Phase??Effort?numerous studies to understand process?liberation and mineralogical characterization?pulp and mineral surface chemistry?flotation kinetics and entrainment?extensive internal and external manpower?Brunswick, Noranda Technology Centre?CanMet, AMTEL, MinnovEx, Lakefield Research, McGill University?small capital expenditure

May 1, 2002

By W. A. Jones

THE Ross mine, a subsidiary operation of Hollinger Consolidated Gold Mines, Limited, is situated near the north end of lot 1, concession 2, Hislop township, Ontario. The property comprises the north half of lot 1, concession 2, and the south one-third of lot 1, concession 3. It is readily reached by a good motor road from the village of Ramore, 7.5 miles to the southeast on the Temiskaming and Northern Ontario railway. The-mine has been developed to a depth of 900 feet and the current daily production rate is about 260 tons. From the inception of operations in March, 1935, until December 31st, 1942, 455,720 tons of ore with a total value of $4,169,-316 have been milled. The silver to gold ratio of 1.48 to 1 is unusually high for Ontario gold mines. The deposit is interesting because the relationship between hydrothermal metamorphism and three successive stages of fracturing and mineralization is marked with considerable clarity. During the past seven years, detailed geological maps of the mine have been kept up to date, many thousands of feet of diamond-drill core have been logged, and numerous thin and polished ore sections have been studied. The present paper describes the structure and mineralogy of the orebodies.

Jan 1, 1944

By Robert B. Parsons

"During hard times, the focus on tax issues makes a slight change in direction. Mining companies contemplate the tax treatment of transactions and circumstances which are the product of a difficult financial environment. Some of these issues are discussed in this month's edition of Tax Notes.Every industrial sector in Canada is undergoing a major restructuring of some form, and the mining industry is not an exception. The longest recession since the Great Depression continues to affect the economy. Mining firms seek to bring their debt/equity ratios into line, and try to replenish depleted retained earnings by selling assets. This month, Tax Notes briefly examines some of the tax issues which are generally encountered during the course of such a restructuring process.Debt SettlementOne question which commonly arises during hard times concerns the tax treatment of a "" gain "" realized by a debtor on the settlement of a debt. Consider, for example, a simple situation where a creditor wants to protect itself from further losses, and makes a deal with the mining company to accept a cash payment of $8 million in full settlement of a $10 million loan. In financial terms, the debtor has made a $2 million gain on the settlement of the debt. What is the tax treatment of that gain?The Income Tax Act (the Act) contains provisions in section 80 of the Act and in section 5400 of the Income Tax Regulations which deal specifically with this question. First of all, it is noted that the $2 million gain is not brought directly into income for tax purposes. However, as indicated below, the gain could affect the debtor's income indirectly to the extent that certain of the debtor's tax pools must be reduced by the amount of the gain."

Jan 1, 1993

By M. J. Dry, G. B. Harris

"This paper presents basic chemistry and operating conditions for the hydrolysis of ferric chloride into solid hematite and gaseous hydrogen chloride, and shows how this unit operation can be applied in chloride hydrometallurgy to regenerate strong hydrochloric acid and reject iron without also rejecting valuable metals such as nickel, copper and cobalt. Two examples are used to illustrate the hydrolysis technology and compare it to existing technology. The first is the regeneration of spent steel pickling acid, comparing hydrolysis to conventional pyrohydrolysis. The second example is the processing of a hypothetical low grade nickel laterite, comparing the novel chloride hydrolysis route to conventional sulphate HPAL technology.INTRODUCTION Whilst, in many respects, the control and removal of dissolved iron from chloride leach solutions can resemble the manner in which it is done in sulphate systems, chloride chemistry additionally offers the ability to achieve the same objectives in different ways (Harris, 2014). Conventionally, iron is oxidised to its ferric state (if necessary) and then precipitated with a base, usually magnesia where the feed is a laterite and lime where it is a sulphide, since calcium will precipitate sulphate formed during leaching. One method for controlling iron is to form FeOOH, either ß-FeOOH (akaganéite), a-FeOOH (goethite), or a mixture thereof (Fillipou and Choi, 2002). However, if akaganéite is formed, the precipitate will contain a significant chloride component (as high as 7% Cl), leading to chloride losses and difficulty in satisfactorily disposing of the residue. Washing chloride from akaganéite is almost impossible due to the propensity of the solids to undergo peptization. The conventional approach requires the addition of a base, but it is based to some extent on controlled supersaturation precipitation (Demopoulos, 2009), which produces a more uniform and crystalline material and is far more attractive than, for example, the turboaeration process proposed by Great Central Mines in their chloride copper process (Raudsepp & Beattie, 1986)."

Jan 1, 2016