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By Gurinder Kaur

Selenium (Se) based materials find wide applications in rectifiers, solar cells, photographic exposure meters, data storage devices, xerography and anticancer agents. They are also used in the glass industry to eliminate bubbles and remove undesirable tints produced by iron. In addition, Se is highly reactive towards a wealth of chemicals that can be potentially exploited to convert Se into other functional materials such as CdSe, ZnSe, Ag2Se. Here, we report a review of structural investigations of Se based materials in glassy and nanostructured forms. Glasses having varying amounts of Se and Tellurium (Te) were doped with group IV and V elements such as antimony and tin. Structural changes accompanying the composition variation were characterized with x-ray photoelectron spectroscopy, differential scanning calorimetry and x-ray absorption near edge spectroscopy. At the same time Se-Te nanoalloys were synthesized in aqueous micellar phase using Na2SeO3/Na2TeO3 as the Se/Te source. Morphology change from nanoparticles to nanoribbons was investigated using Scanning and Transmission Electron Microscopy (SEM/TEM) techniques. Structural investigations were also done for well defined morphologies of Se based nano-biomaterials obtained in the presence of water soluble protein bovine serum albumin (BSA).

Aug 1, 2013

By K. A. Natarajan, M. N. Chandraprabha

Selective separation of minerals from complex sulphide ores is a challenging task and it is often difficult to get commercially acceptable individual concentrates by conventional selective flotation using inorganic collector reagents. Microbially-induced mineral beneficiation has proved to be more effective, economically viable and an environmentally benign process for the effective separation of various minerals. Applications of microbially-induced mineral beneficiation are demonstrated in this paper with respect to beneficiation of complex multimetal sulfides. The role of adapted microorganisms and bioreagents in the beneficiation of complex sulphide minerals are also illustrated.

Jan 1, 2009

By F. Khomamizadeh

In this study, deep cryogenic treatment was applied to A319 cast aluminum samples. Although the cryogenic treatment didn't have any significant effect on mechanical properties of the well degassed and fluxed samples, but the tensile strength of the samples containing a considerable amount of gas and shrinkage defects was improved surprisingly, This improvement was attributed to the strengthening of the a-aluminum matrix which slows down the propagation of the existing defects. There was no significant increase in the hardness after cryogenic treatment, The abrasion resistance of the alloy was improved after cryogenic treatment, by developing a homogeneous protector shield, composed of abrasive grains penetrated into the soft aluminum matrix and kept tight.

Jan 1, 2005

By A. J. Makoka, B. C. Qi

Reliable monitoring of corrosion is vitally important in the combat against corrosion and over the last two decades the interpretation of electrochemical noise has received considerable attention as a means to discriminate between different types of corrosion. To this end, many different analytical methods have been proposed, such as power spectral density analysis and analysis via various other stochastic criteria. However, although many corrosion systems are nonlinear and therefore not readily interpretable by the abovementioned analytical approaches, few studies in the analysis of electrochemical noise to date have exploited advances made in the analysis of nonlinear systems. In this paper, the use of phase space methods to analyze and detect change in corrosion systems via electrochemical noise is considered. In particular, the electrochemical noise data are used to reconstruct trajectories in the so-called phase space of the system and changes in the topology of these trajectories or attractors as represented by correlation dimension curves are consequently interpreted as an indication of change in the dynamics of the system.

Jan 1, 2005

By C. K. Wilton

"The Agnew Lake uranium deposits were discovered in 1953 following the discovery of the Elliot Lake deposits to the west. The original property was optioned to Kerr Addison Mines Limited who added additional claims by staking. Agnew Lake Mines Limited was incorporated in 1967 to develop the property and a shaft was sunk to 1040 metres and five levels developed before work was suspended due to low uranium prices at the end of1970.In 1974-75 the mine was dewatered and production started in 1977. By 1978 reserves were estimated at 10,000,000 tonnes averaging 0.35 kg. U10 , per tonne. Underground operations were terminated in 1980 although a uranium leaching operation was continued until early 1983.The deposits lie near the contact of Huronian metasediments with underlying Algoman granite. The sediments consist of arkose, conglomerate, argillite and quartzite with the uranium mineralogy mainly confined to oligomictic quartz pebble conglomerate. The higher uranium values are related to conglomerate with highest percentage of pebbles. The chief uranium minerals are uranothorite and monazite. It is of interest that the uranium thorium ratio differs appreciably from that of the Elliot Lake deposits. This fact along with the fact that the Elliot Lake sediments were deposited by paleocurrents from the northwest whereas the Agnew Lake sediments were deposited by paleocurrents from the northeast indicates widely separate sources for the deposits. It is suggested that the Agnew Lake uranium deposits are syngenetic placers deposited under anoxygenic atmospheric conditions."

Jan 1, 1986

By Gonzalo Díaz, Diego Mesa, Willy Kracht

"It is well known that frothers affect the amount of water that is transferred to the froth, which has an effect on both the froth stability and the water recovery. On the other hand, since non-selective recovery by entrainment is directly related to water recovery, it can be said that frothers have an indirect effect on flotation selectivity. Recent research on this subject has shown that the non-selective recovery by entrainment, which is characterized by the entrainment factor, is frother dependent. In other words, the entrainment factor is not unique, but depends on frother type.Having different entrainment factors implies that for the same water recovery, the amount of undesired particles reporting to the concentrate may vary if one changes the frother type, which suggests, as a possible explanation, that it is not only the amount of water in the froth what is affected by frother type, but also the froth structure.The purpose of the current work is to study the effect of frother type on foam structure (two phase froth). A quasi-2D cell operated with a slot sparger was used to study the foam structure in the presence of three different frothers: Methyl Isobutyl Carbinol (MIBC), OrePrep®549, and Octanol at the same gas flow rate and reagent dosage. The foam structure was studied using image analysis, and an algorithm based on textural analysis was developed to classify the foams. The results show that it is possible to classify foams according to the frother used, which proves that frothers have an effect on the foam structure.INTRODUCTIONFrothers are usually dosed paying attention to froth stability, condition that is commonly estimated by sight, according to the operator's criteria and experience. This happens because there is not an established procedure or technique for frother characterization, generating qualitative descriptions such as “powerful” or “selective” frothers, which lack of scientific thoroughness and remain under subjective factors. Nevertheless, several works have been done in this line of research. Moyo et al. (2007) classified frothers based on their water-carrying capacity, proving that this characteristic is related with gas holdup and frother type. Previously, Trahar (1981) had related water recovery and gangue particles recovery, defining the entrainment value (ENT). Nowadays it is known that entrainment affects both hydrophilic and hydrophobic because it is not a selective process. In the last decade some studies (for example the one of Konopacka and Drzymala (2010)) delved into different entrainment behaviours dependent mainly on the flotation type (batch or continuous, agitated or columnar, etc.), but there were no studies on the effect of frother type regarding entrainment, since Rahal et al. (2001) argued that the ENT factor was independent of the frother type and concentration, and froth height."

Jan 1, 2016

By W. L. Goodwin

Twenty-five years ago mining engineering in Canada was not a profession. To-day the members of the mining fraternity can fairly claim for 10themselves the professional status. If their pretension is not fully warranted by fact it is not for lack of any technical attainment or service to the public but by reason merely of their neglect to cultivate the cohesion and consciousness that are the outward and visible signs of a professional body. This paper is an attempt, first to sketch briefly the course of the events during the past thirty-five years that have resulted in organizing the mining industry of this country in its present form; then to notice the principal features of the professional organization of this day; and finally to point out that an important part of the work of the mining engineer remains in the state of chaos that characterized the whole of it three or four decades ago, and to suggest a remedy. Thirty years ago there came a great wave of interest in mining in Canada, based principally upon the discovery of gold-quartz and gold-copper throughout wide areas in Nova Scotia, Ontario and British Columbia.

Jan 1, 1926

By D. Sharma, A. K. Singh, R. Singh, P. K. Mandal, M. Sarkar

"This paper deals with the stability investigations carried out at the XIVth seam of Jitpur colliery. The study was conducted to investigate the possible causes of roof cavity formation and face spalling at the middle slice face of block-3 longwall panel and to suggest remedial measures. The instrumentation and monitoring work was carried out in the panel over a period of nine months. On the basis of observations, it was found that if the maximum face span was reduced from the existing 4.8 m to 3.6 m, and if the face time schedule cycle was reduced from a maximum of 37 days to about 18 days, this problem could be eliminated. The recommendations of CMRI have been implemented in the middle slice face of block-4 panel with success. IntroductionModerate to steeply dipping, undisturbed seams of uniform thickness are worked by way of inclined slicing parallel to walls. In this method, the seams are treated as a combination of several moderately thick seams dipping parallel to roof and floor. Numerous variations of multislice mining have been used worldwide to get high coal recovery under local conditions of geology, subsidence control, proness to spontaneous combustion, statutes and economics. Multislice mining can proceed either downward descending from the roof or upward ascending from the floor. Ascending methods require backfill behind the working face to provide a base for the next slice. It is also adopted for surface protection against subsidence or mining under a massive roof. This paper presents a scientific study conducted in Jitpur colliery, IISCO where a 9 m thick seam is mined in three slices in ascending order with stowing."

Jan 1, 2002

By T. Guan, G. Fu, X. Zhou, L. Deng

"One kind of tailings from gravity separation of polymetallic mine contains 0.5–0.8% SnO2. The proportion of –0.037 mm size fraction of the tailings is 37.12%, and the distribution rate of SnO2 is 60.32% in it. For this tailings, two processing technology was carried out. One was felt-shaking table gravity separation in which the concentrate with a grade of 30% SnO2 at a recovery of 10% was obtained. Another was flotation-gravity separation in which the concentrate with a grade of 51.20% SnO2 at a recovery of 51.69% was obtained, but the dosage of collectors was as much as 990g/t. Therefore, the experimental research on the influence of grain size composition on the cassiterite recovery were conducted. The results show that: (1) the flotation recovery of the cassiterite distributed in +0.043 mm size fraction is only 10%, flotation recovery is not suitable for it; (2) a portion of cassiterite distributed in –0.01+0.005 mm size fraction could be recovered by flotation, but the tin flotation performance will be worsened rapidly and the dosage of collectors will be increased due to the increase of the content of –0.010 mm size fraction; (3) flotation processing is not suitable for –0.005 mm size fraction of the tailings. According to the results, a new technology has been carried out, that is discarding tailings by gravity separation-hydrocyclone desliming-flotation-gravity separation processing flow. The processing index is close to that of the flotation-gravity separation processing flow, and the collector dosage is decreased to 360 g/t by this processing technology. And, it has been achieved that the cassiterite slime is recovered economically and reasonably.INTRODUCTIONAs the density of cassiterite is higher than that of gangue, gravity separation is considered to be a low cost, pollution free, and effective process for cassiterite recovery (Wills, 2009). However, cassiterite is a kind of fragile mineral, over crushing is easy to take place and a large amount of slime is inevitably produced in the crushing and grinding of cassiterite. For the cassiterite slime exists in –0.043 mm size fraction, the efficiency of gravity separation decreases sharply. The production practice shows that, for the fine cassiterite, the recovery of tin exists in –0.043 mm +0.010 mm size fraction is about 13% through shaking table gravity separation, and the tin exists in –0.010 mm size fraction is almost impossible to be recovered by gravity separation. If flotation is adopted to recover fine cassiterite, the problems of high reagent dosage, high cost, environmental pollution, and poor economic benefit would take place. Therefore, the recovery of cassiterite slime is a worldwide problem. A key way to increase the utilization of tin resource and increase the economic benefit of tin mines is developing suitable beneficiation process for fine cassiterite."

Jan 1, 2016

By E. Latorre, T. S. Golosinski

ABSTRACT; his paper proposes new methodology to define the pit limits that yield the maximum net present value (NPV) for a deposit, under a given economic scenario and for a given discount rate. The method uses an algorithm that combines dynamic programming and heuristics. It was tested for evaluating deposits with different sizes and various grade distributions. For the discount rate of zero, the results confirm that the economic pit limits are the same as that defined using Lerchs Grossman method. However, when discount rates higher than zero are used, the pit limits differ, yielding a higher NPV.

Jan 1, 2011

By J. Guha, el, G. Bouchard, W. Zuckerk, J. Carignan, G. Archambault

The Gwillim Mine, located 8 km northwest of Chibougamau, is underlain by two mafic volcanic cycles separated by a dominantly felsic cycle. These rocks are part of the Gilman Formation of the Roy Group. The mafic rocks are cut by weak shear zones containing the "North" and "Main" veins, both east-west striking gold-bearing structures dipping 75° to the north. The felsic cycle, which is also gold-bearing, contains textures suggesting a syngenetic origin. The Gwillim Mine presents an excellent opportunity for the study of what may be two coexisting gold deposits, a volcanogenic and a veine type.

Jan 1, 1984

By A. Azizi, P. Blatter, A. Bouajila

ABSTRACT In-situ monitoring of gold dissolution by means of a rotating electrochemical quartzcrystal microbalance unveiled dramatic decreases in gold leaching from sulphide-rich ore after 360 minutes in an actual cyanidation circuit. Pre-oxidation was effective in enhancing gold extraction by preventing a passive film from forming on gold surfaces. This work aims to highlight efforts undertaken to determine (1) how gold cyanidation is limited by passivation, (2) what reactions and mechanisms are involved during sulphide-rich ore cyanidation, and (3) how peroxidation efficiency of an industrial sulphide ore is controlled by galvanic associations between its sulphide constituents.

Jan 1, 2013

By A. R. Chambers

At the 1924 Annual Meeting of the Institute, held in Toronto, the writer presented some notes on the occurrence of salt at Malagash, Nova Scotia, together with a few remarks on the uses of salt. The development of these salt mines has attracted considerable attention to the district, and it may be of interest at this time to call attention to some of the newer uses of salt, and to give a brief account of the genesis of the Maritime salines, As it is not proposed to treat the subject in technical detail, and the paper is written in a lighter vein than is usual in contributions to your Transactions, you will please overlook any variations from a strictly technical method of presentation. The world's supply of salt is obtained in three principal ways: (1) By flooding shallow areas, or pans, with sea water, allowing the water to evaporate naturally by the heat of the sun's rays, and collecting the residue of solid salt. This method is employed, for example, at Turks Island, B.W.I. (2) By mining the rock salt in its natural state, and preparing it for market by a grinding process. This is the method adopted at Malagash, which is the only place in Canada where salt is actually mined. (3) By drilling a hole into an underground salt deposit, forcing fresh water clown the hole, and, after it has become saturated with salt, pumping the brine to the surface and recovering the salt by evaporation. This is the method pursued by the Canadian Salt Company, the Dominion Salt Company, and other producers in Ontario.

Jan 1, 1929

By Cesar Carrasco

Mine reconciliation is the art and science of comparing predictions and real-world outcomes with the intent of revealing the true quality of performance of models, planning, mining, and mineral processing. When mine reconciliation is conducted in a systematic, transparent and sustainable way it can play a central role in the governance of Mineral Resource and Mineral Reserve (MRMR) estimation and reporting. The core processes of modelling, planning, mining, and processing need to be transparent to be able to demonstrate that MRMR are reliable predictors of mine performance and value. Transparency is also necessary for mine technical staff to generate meaningful analyses, conclusions, and business improvement actions that demonstrably maximise value for all stakeholders. Most mines have some form of mine reconciliation practice, however because there is no agreed industry standard, and because mine reconciliation is difficult for a variety of reasons, it is often unsustained and/or ineffective at delivering the required transparency of performance. To deliver true governance of MRMR and business value, mine reconciliation must be sustainable. There are two categories of issues that combine to make mine reconciliation extremely difficult to sustain, these are technical, and people related. Technical issues include defining standard terms, accurately tracking material flows, data availability/adequacy/quality, calculation of key performance indicators and tolerance limits, analysis, and interpretation of results, understanding limitations of modelling techniques, and defining appropriate actions that can deliver value. These technical challenges are non-trivial, however compounding these are a range of people issues that include personal agendas, scepticism, lack of knowledge and experience, poor teamwork, absent leadership, toxic workplace culture, staff turnover, ineffective communication, siloed organisational structure, and lack of deliberate change management. All these problems can be solved with clarity of purpose, definition of the process of mine reconciliation, discipline in following the process, appropriate resourcing, and commitment to success across the entire organisation. Outlined in this paper is a management system that delivers sustainable mine reconciliation by addressing both the technical and people issues described above. This approach can deliver significant value for a mine and adds a robust, defensible governance over MRMR estimation and reporting.

Oct 1, 2024

By Luino Jr. Dell'osso, Richard L. Every

The enormity of the methane-in-coal problem is discussed, with a brief summary of the state-of-the-art. Laboratory techniques and data on the desorption of methane from Pittsburgh seam coal are presented and discussed and include the effect of time, temperature and vacuum. Under laboratory conditions, it was possible to displace 90 per cent of the residual methane by flooding the coal samples with carbon dioxide. Carbon dioxide was found to be three times more effective than air and almost five times more effective than helium.

Jan 1, 1972

By C. S. Touchard, F. Bourgeois, L. Cassayre, Julcour-Lebigue C.

Developing a hydrometallurgical process that can overcome the refractory nature of chalcopyrite (CuFeS2) to leaching still eludes the minerals industry, despite major research efforts spanning decades. The several leaching experiments of this ore in sulfuric acid tend toward the same conclusion that the precipitation of elemental sulfur or iron containing species are the main dissolution inhibitors. Describing both the electrolyte composition and the various solid phases in equilibrium for the Fe-H2SO4-H2O system is essential to overcome this issue and to find an operating window. According to the thermodynamic models and to the thermodynamic data, we demonstrate, in this study, the need to use the Specific ion Interactive Theory (SIT) model to describe complex electrolytic systems through a limited number of parameters. Hence, the binary interactions for our case study have to be defined and estimated. This work develops a methodology to determine these parameters of the SIT model up to 90°C and an acid concentration of 1 mol/kg from published data for H2SO4-H2O and Fe(II)-H2SO4-H2O sub-systems or from new experimental data for the Fe(III)-H2SO4-H2O one. This method will eventually be applied to copper systems to lead to a thermodynamic description of the complete CuFeS2-H2SO4-H2O system. INTRODUCTION A leaching process consists in the dissolution of a solid phase into an aqueous medium in order to extract compounds of interest. It is a key step in the hydrometallurgical processes used in the primary production and recycling of metal components. One of the main leaching issues is the formation of passivating layers on the surface of solid particles, whose consequence is a partial or total hindrance of the dissolution. The leaching of chalcopyrite (CuFeS2) in sulfuric acid is a prime example. No industrial solution for the atmospheric pressure leaching of this ore has been developed to date because of passivation phenomena caused by the formation of elemental sulfur or iron-containing precipitates on the surface of the particles (Li, Kawashima, Li, Chandra, & Gerson, 2013). In the 1970s, the Pourbaix diagrams established for the Cu-Fe-S-H2O system at 25°C for low concentrated solutions (Garrels & Christ, 1965; Peters, 1976) agreed that copper and iron are fully dissolved at high potential and in acidic medium (pH < 4). However, they neglected the many stable solid phases that can form in these conditions. In addition, the Pourbaix diagrams of chalcopyrite in water, calculated with two recent databases (FactPS and Thermoddem 2017) associated to FactSage and PhreeqC softwares respectively, show large discrepancies at 75°C (Figure 1). Indeed, at high potential, FactSage predicts the formation of goethite FeOOH at a pH value of 1, while PhreeqC predicts the formation of jarosite (H3O)[Fe3(SO4)2(OH)6] for pH greater than 2.5.

Jan 1, 2019

By L. Gawlik

Since the beginning of the 20th century, coal has been the world?s main source of primary energy. In the last few decades, consumption of coal has gradually decreased in some European countries and elsewhere due to the introduction of other energy sources. Regardless, industry continues to use solid fuels for energy production despite of their association with carbon dioxide emissions (about 7 billion Mg). For global development going forward, it is important to estimate what level of energy consumption can be expected as far into the future as the next few decades. To answer this question, specialized global institutions such as the International Energy Agency, the World Energy Council, the World Coal Institute, the U.S. Energy Information Administration, the International Institute for Applied Systems Analysis, as well as oil companies (BP, Shell), conduct periodic forecasts of world energy consumption. The development of such forecasts is very complex because their reliability is influenced by many factors that are difficult to estimate, such as economic development, population growth, climate change, and public awareness. We are all aware that the global demand for electricity will rise significantly in the coming years as a result of anticipated population growth, industrial development, rising living standards, and the general development of civilization. The world?s mineable resources in 2010 were as follows: coal 665.6 million Mg, brown coal 195.4 billion Mg, oil 163 million Mg, and natural gas 185.5 billion m3. The annual global primary energy demand in 2008 was more than 12 billion toe (12,267 Mtoe). In 2006, electricity production in the world amounted to 18,921 TW?h. The structure of the primary energy mix in TW?h (2006) was as follows: coal 41.0%; natural gas 20.1%; nuclear fuel 14.8%; hydro energy 16.0%; liquid fuels 5.8%; and other renewable energy sources 2.3%. The European Union (EU) is one of the largest coal consumers in the world. In 2010, the EU-27 produced 396.1 million Mg of brown coal, and 132.9 million Mg of hard coal; 188 million Mg of coal was imported from outside the EU. The largest hard coal producers in the EU-27 are Poland, Great Britain, Germany, the Czech Republic, and Spain; major brown coal producers are Germany, Greece, Poland, the Czech Republic, and Hungary. For many years, the Polish energy sector has been based on domestic fuel sources ? hard coal and brown coal. The characteristic feature of the Polish balance of primary energy resources is a very high share of coal ? much higher than the world average. Pursuing the decarbonisation of the Polish economy may jeopardize Poland?s energy security, leading to a significant increase in electricity prices, which would hamper the country?s economic development. Price volatility and supply uncertainty are now the dominant features of the international markets for oil and natural gas. The high share of these fuels in meeting energy needs is the reason for unrest in many countries, including those in the EU. Under these circumstances, coal may become the stabilizing element of EU energy security.

Aug 1, 2013

By S. A. Bradford

The twenty years before World War I was the Golden Age of copper smelting in British Columbia. In this short time, the smelters developed from small, primitive units to large, efficient operations. The first copper claims had been staked on Howe Sound and Knight Inlet in 1864, and there was extensive copper mining in the interior by the mid-1880s, but before 1895, all ore was shipped out of the country for smelting, converting and refining. The first interest in smelter construction was undoubtedly inspired by a Provincial bonus and Dominion land grants offered to smelter builders. The early smelters made use of small blast furnaces which were designed to smelt any kind of ore, but usually far too little ore was available. The first smelter seems to have been the McRae furnace on the Spillimacheen River (1883), followed by Vancouver (1889), Revelstoke (1891), and Golden (1891) (1). They each smelted a few tons of galena and then quickly closed down permanently for lack of ore. Only smelters that actually produced some copper matte are described in the following sections.

Jan 1, 1999

By F. Bosché

Previous research has shown that ?Scan-vs-BIM? systems are powerful to provide valuable information for tracking structural works (progress, quality, safety). However, the transferability of this capability to other construction areas such as MEP works has not been assessed so far. Comparatively, the construction of MEP systems, in particular pipes and ducts, tends to be more flexible with respect to the positioning of individual components, so that Scan-vs-BIM systems could be defeated when tracking MEP installation works. This paper presents recent results on the feasibility and performance of using a Scan-vs- BIM system to track MEP works. The approach followed is presented and then tested with two real-life challenging case studies were conducted simultaneously but totally independently in Canada and Italy. The results show that, as expected, pipes and ducts tend to be more loosely positioned than structural elements leading to a poorer performance of the Scan-vs-BIM system. Nonetheless, it appears that the system works well to assess the level of conformance of site installation works, providing valuable information for estimating emerging performance metrics like ?percent built as-designed?. In addition, the proposed system could also be useful to accelerate and thus reduce the cost of delivering as-built BIM models for in the case of new builds.

Aug 1, 2013

By M. T. Ho, D. E. Wiley

The iron and steel industry accounts for almost 5 % of the total world CO2 emissions. Optimisation of the steelmaking process has led to significant reductions in the energy intensity to the point where it is now close to the thermodynamic limit. Further reductions are not likely to be achieved with efficiency improvement alone and will require the development of novel or breakthrough technologies. This paper will show the costs of implementing CO2 capture at direct atmospheric emission points for a number of iron and steel production processes. These include a conventional process, top gas recycling processes, the Corex and Hismelt smelt reduction processes and the Midrex direct reduction process. Depending on the point source emission, costs of capture with existing chemical absorption technology at iron and steel plants can be similar to capturing CO2 at pulverised coal fired power plants.

Jan 1, 2015