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By Trang T. Tran-Valade

With continually increasing energy prices, the mining industry has been on the search for new energy optimization technologies. One area that is garnering great interest is Ventilation-On-Demand (VOD). Prior to selection and implementation of a VOD solution, it is important to fully understand the mine requirements as well as its existing infrastructure and the interaction with other automation in place at the site. With this information, a business case can be generated including a cost versus benefit comparison for various control strategies. To assist in the development of the business case, this paper will identify key areas for consideration and recommendations for an implementation plan.

May 1, 2013

By A. Aaltonen, S. Paloranta, H. Myllykangas

A property based dynamic model of flotation was built and validated for training purposes. The model is based on the work of the AMIRA P9 project. The recovery of each particle with composition and size is calculated in a given simulation step. The model takes into account machine and operational parameters such as air flowrate and froth height. The model was created using fullscale test data on Pyhlisalmi Cu-Zn-pyrite ore with flotation kinetics of multiphase particles determined. Simulation and validation shows that model can predict the dynamic behavior of the process accurately enough for training purposes.

Jan 1, 2009

By S. M. Bradshaw, E. Charikinya

"Microwave induced cracks have the potential to enhance metal recovery from coarse sphalerite particles in heap leaching operations by creating new crack surface areas for lixiviant and enhancing value mineral exposure. The mode of fracture and the extent of mineral exposure due to microwave induced cracks have not yet been investigated. The objective of this study was to determine the extent of particle damage and mineral exposure in microwave treated particles. This was done using X-ray computed tomography (XCT) and image analysis techniques. XCT analysis was conducted on small (–5+4.75 mm), medium (–16+9.5 mm), and large (–25+19 mm) sphalerite ore particles before and after microwave treatment (MT). Geometrical properties, such as volume and surface area of each mineral phase in each particle was determined from the XCT reconstructed images using VGStudioMax image analysis software. These geometrical properties were used to calculate the interfacial areas of sulphide mineral grains in microwave treated particles before and after MT. The ratio of specific interfacial area after MT to specific interfacial area before treatment was used as an indicator of the degree of preferential grain boundary fracture. The results showed significant grain boundary fracture after MT at all sizes. For small sized particles, about 31% of the interfacial area was lost compared to 23 and 16% for medium and large particles, respectively. The results also showed an increase in the degree of mineral grain exposure of 28, 26, and 15% for small, medium, and large particles, respectively, after MT. These results provide experimental evidence supporting improved mineral exposure due to MT. INTRODUCTIONFor some years it has been suggested that microwave treatment (MT) of ores might result in preferential grain boundary fracture that would have benefits such as improved grain exposure and particle weakening. (Kingman, 2006). Most of the experimental work investigating the application of microwaves to mineral processing flow sheets has focused on assessing the benefits of applying microwave technology to flow sheets consisting of size reduction and mechanical flotation cells (Kingman et al., 2004). Experimental studies have shown that coarse crushing during tertiary grinding of microwave treated ore resulted in a better liberated coarser flotation feed (Scott, Bradshaw, & Eksteen, 2008). It has been suggested that improved liberation in milled flotation feed, was due to the presence of grain boundary fracture in microwave treated particles. However, this improvement in coarse particle liberation does not necessarily translate to a significant improvement in downstream flotation recovery (Kobusheshe, 2010). This is as a result of the size limit to the flotation of coarse material, due to detachment forces acting on particle-bubble aggregates, which increase as the particle size increases (Jameson, 2012). Current conventional, mechanically agitated flotation cells are not designed to float coarse material (Jameson, 2012). Hence it has been difficult to show the downstream processing benefits of applying microwaves to ores processed by comminution followed by flotation (Kobusheshe, 2010). It is clear from investigations carried out so far that inappropriate downstream exploitation of microwave treated ore would fail to realise a meaningful process benefit (Kobusheshe, 2010; Ali & Bradshaw, 2011)."

Jan 1, 2016

By S. B. Kang

Magnesium has poor ductility at temperatures lower than 225°C and, as a result, Mg alloy sheets are produced via fairly complex thermomechanical processes consisting of numerous sequential steps of hot (warm) rolling with low reduction and intermediate recrystallization annealing operations. In context of the present study, a simple technology for the fabrication of magnesium sheets by hot (warm) rolling was applied to various magnesium alloys. The misch metal addition in those AZ alloys was done to evaluate the deformation behavior. Tensile tests were carried out for those AZ alloys after applying different heat treatments. The precipitation of ß phase (Mg17Al12 phase) induced different microstructures with various cooling method from solution treatment temperature, and also with various annealing treatment temperatures.

Jan 1, 2006

By G. K. Lee, E. R. Mitchell

Designers of combustion processes may select aerodynamic conditions which produce only superfine fly ash. Although it is not usually anticipated that this will create a problem, such as has been found to agglomerate in high-velocity gas streams, to plug mechanical dust separators in a short time, and to contribute to atmospheric pollution. The problem is a fundamental one, and may be approached in several ways. The authors, in the course of their combustion research program, had occasion to examine the agglomeration of ash, ranging from sub-micron to 17 microns in size, produced in a (coal and oil) dual-fuel-fired steam generator. Several theories, supported by extensive laboratory studies, have provided some understanding of a probable mechanism of agglomeration. As a result, certain precautions are suggested in the design and selection of combustion processes and equipment.

Jan 1, 1962

By C. G. McLachlan

INTRODUCTION The work described in the following paper was under-taken with a view to determining, if possible, the relative importance of some of the phenomena on which flotation seems to depend, in the hope that, if this information could be obtained, it would be of value in dealing with the problem as a whole. At the outset, brief reference will be made to three papers which had a considerable bearing on the course followed in the present investigation. In 1919, Langmuir, in a paper on 'The Mechanism of the Surface Phenomena of Flotation', showed that mono-molecular films of very great stability could be produced on solid surfaces with oleic acid, but that pure paraffin oil, though spreading readily on a dean dry surface, was easily displaced by water.

Jan 1, 1926

By Steven Hart

In September 2009, Newmont began the commissioning of a 3 stage crushing and milling circuit at its Boddington Gold Operation in Western Australia. The Boddington ore has been recognized as one of the hardest and most abrasive ores treated to date and this played a pivotal role in the selection of crushing and HPGR technology for this operation as opposed to the more conventional SABC circuit. This paper will examine the scale up from laboratory to pilot plant and full scale operation of the crushing circuit. There have been many challenges to overcome in the first 18 months of operation; however, the HPGRs have in general met design expectations and performance is expected to improve further with ongoing design changes

Jan 1, 2012

By T. P. Weldum, W. Conger

"These studies address the relationship between mill media sizing and its grinding efficiency. Starting with the results from a review of the literature, the issues of initial media sizing for a new ball milling circuit, and then optimal media sizing for an existing milling operation, were studied. The Functional Performance parameters “Mill Grinding Efficiency” and cumulative “Mill Grinding Rates” from both plant and test-scale equipment were used, and provide valuable new insight into this topic. A plant media sizing diagnostic tool is presented, as are newly developed testing equipment and evaluation methods, and recent case studies.REVIEW OF MEDIA SIZING LITERATURE For a plant metallurgist to answer the question “How can I maximize plant profit by manipulating this grinding circuit variable?” she must know what effect the variable has on grinding circuit efficiency. Despite the significant cost of grinding media and its potential effect on production capacity, the ‘best’ media sizing remains ill-defined for any given ball mill circuit in the industry today. The underlying reasons for this will be discussed. But the importance of this issue drove Metcom and its industrial partners to take on the challenge of how to engineer the ball charge for an existing grinding circuit. In the absence of any proven method, the first step was a review of the literature. Sponsored by Cleveland-Cliffs, Inc., a broad review of the literature was undertaken, producing “The Effect of Media Sizing on Ball Milling Efficiency” (McIvor, 1997). Among hundreds of publications that were reviewed that discuss the topics of media sizing or wear, forty-five were studied in detail. These were grouped into: plant experiences; laboratory and pilot plant investigations; media wear studies; population balance modeling studies; and general papers on ball milling which included the topic of media sizing. The reader is encouraged to refer to that review. The findings remain unchanged, although some relevant papers have been written since (e.g. Staples et al, 1997; Banasi et al, 1999; Orford et al, 2006; LaMarsh, 2015). The main findings of the review were as follows:"

Jan 1, 2018

By A. C. Munro

The concrete work on the new Britannia mill was started in April, 1922. The erection of steel commenced on July 10th, following. The installation of wood work and machinery , began on November 4th of the same year and was pushed to completion in January, 1923. The new mill building is an all steel structure enclosed with galvanized corrugated steel. All main floors and foundations are of reinforced concrete, which makes the building practically fireproof throughout. The mill building rises on a steep hillside to a vertical elevation of 210 feet and has seven distinct floors, for the various opera-tions. Only one elevator, with 30-foot centres, is used in the entire mill. The building is exceptionally roomy and well lighted, both by day and night. The capacity of the mill, as originally designed, was to be 2000 tons daily, but this tonnage can be readily increased to over 3000 tons daily by making slight changes in the fine grinding equipment; in fact, an average of 2700 tons per 24 hours was maintained throughout the month of September.

Jan 1, 1923

By H. Memarian

In the last few decades, many developing countries have tried to expand and improve upon higher education, which is acknowledged to be the leading factor for development. In this respect, develiping countries have significantly increased the number of tertiary institutions and their students. These rapid expansions, along with all the benefits, have drawbacks as well. An example is the status of mining engineering education in Iran. Presently, the number of active mining engineering departments in Iran (27) is more than the sum of similar departments in Canada, Australia, the United Kingdom, and South Africa (23 altogether). Also, the number of annual mining graduates in Iran (645) is more than the cumulative graduates of the United States, Canada, the United Kingdom, and Australia (613). The expansion of mining engineering education in Iran has coincided with the closing or merging of similar mining departments, as well as a decline in the number of interested students in the industrialized world. The present study shows that the need for development and the excessive number of high school graduates, resulting from high population growth in the early 1980s, are the two primary factors influencing the significant expansion of mining engineering education in Iran.

Jan 1, 2007

By R. M. S. Häggblad

The article deals with stabilisation and regeneration of Ce02 and Ce02/Zr02 based Pt water gas shift catalysts, subject to high initial deactivation. The reaction gas species effect on the catalyst deactivation was investigated by H2-TPR. Activity measurements enabled the effect of different promoters, some added to the Ce02 based catalysts and some to the Ce02/Zr02 based Pt catalysts, to be investigated. The catalysts were also characterised by BET and CO-TPR. Deactivated catalysts activity was restored by using various regeneration methods. Of the two selected carriers the Ce02/Zr02 based Pt catalyst showed the highest resilience to deactivation. For the two different carriers, Ce02 and Ce02/Zr02, Wand Re were the best promoters when the catalyst was subject to deactivation. Experiments with Hr TPR indicate a fast initial change in the platinum oxides concentration and composition. The CO-TPR was used to make conclusions about the various regeneration effects of water and oxygen on the catalyst. Finally it is suggested that not one deactivation mechanism is possible and which mechanism that dominates is dependant on the catalyst and the reaction gas composition.

Jan 1, 2005

By B. K. Gorain

"The Air-Metabisulfite (AMBS) process has been developed to treat complex copper, molybdenum and precious metals (gold, silver) bearing ores using brackish and sea water. This process was able to produce significantly better copper concentrate grades and higher recovery than possible using conventional lime and/or cyanide based processes for certain complex ores with high sulphide gangue minerals. The AMBS technology in now used commercially following a rigorous evaluation process emanating from laboratory curiosity to plant applications. In addition, many projects have embraced this technology at a feasibility level involving various complex ore bodies.This paper presents a summary of the findings from testing the AMBS technology on various ores types. Experiences gained from this successful development from bench to piloting and then to plant applications are also presented in this paper.INTRODUCTIONProcessing of sulphide copper, molybdenum and precious metal ores typically involves flotation of copper bearing minerals while depressing non-sulphide and other non-copper sulphide minerals such as pyrite, pyrrhotite and sometimes arsenopyrite. Though in many precious metal ores, the values are in these sulphide minerals as well. The conventional method employed in the industry to produce a saleable copper concentrate requires depression of these non-copper sulphide minerals using an alkaline pH above 9.5, though 10.5 to 11.5 is more common. Alkalinity is controlled by the addition of a pH modifier. Lime is normally employed as a pH modifier due to its relatively low cost; however, the costs associated with adding lime can be significant and the effectiveness of lime as a depressant could be drastically reduced when the process water supplied to the flotation circuit contains high level of dissolved salts. In some cases, a small amount of cyanide is used along with lime to depress non-copper sulphide minerals especially when its proportion to copper sulphide minerals in the ore is higher than three."

Jan 1, 2016

By J. C. Gathje

Newmont&apos;s Phoenix Project is located near Battle Mountain, Nevada and is scheduled to produce copper concentrates containing high precious metal values. High temperature pressure oxidation (PDX) of the concentrates was considered as a treatment option during process development. The metals content in Phoenix concentrates range from: 15-25% for Cu, 1-10% for Zn, 0-2% for Pb and ?27% Fe. The precious metals content of the Phoenix concentrates can range up to ?300 g/t Au and >3,000 g/t Ag. As a consequence it was necessary that any process for consideration should have the capability of recovering both the copper and precious metal values. Typically, gold can easily be leached from the autoclave discharge solids, but silver is chemically bound with the jarosite formed and cannot be directly leached. Laboratory investigations led to the development of a patented PDX process that minimizes the formation of jarosite so that the silver can be leached easily along with the gold. The process was confirmed with extensive pilot plant testing. Excellent solution extraction of copper and zinc was achieved, and both iron and lead were precipitated in the PDX residue. The process produces clean PDX discharge liquors with very low iron concentrations. As an example, conventional PDX techniques resulted in pregnant liquors containing ?5 g/L Fe. However, the Newmont process, which controls the iron and sulfate species, achieved high iron precipitation in the PDX solids and pregnant liquors containing <0.5 g/L Fe. High gold and silver recoveries were achieved by direct cyanidation of the PDX solids. This process has the added benefit of producing PDX solids that demonstrate superior settling and filtration characteristics.

Jan 1, 2006

By K. C. Corin, Z. G. Song, J. G. Wiese

In the present study the effect of using different grinding media, viz, ceramic balls, forged steel balls, 15% Cr steel balls, stainless steel and mixture of stainless steel and 15% Cr steel balls (50:50) on the flotation performance of a Platinum Group Mineral (PGM) UG2 ore was investigated. Test work was conducted using a laboratory scale horizontal tumbling mill and a batch flotation cell. Power draw to achieve a specific P80 was determined for each media type. Changes in flotation behaviour were evaluated in terms of particle size distribution, water recovery, solid recovery and valuable mineral recovery. pH, Eh and DO levels were also measured. Grinding products of five different media produced similar solids and water recovery, which is indicative of the froth characteristics, but the grades and recoveries of PGE and chromite were different. The product obtained when using ceramic media showed the best flotation performance, producing the highest PGE recovery and the lowest Cr2O3 recovery. The products obtained when using stainless steel balls (SS) produced the lowest PGE recovery and highest Cr2O3 grade and recovery. The paper proposes possible reasons to explain these observations which may have significant importance for the operation of a PGM concentrator.

Jan 1, 2015

By N Robb

This paper gives an account of the laboratory testing, plant testing and final inclusion of the two-stage sulphuric acid leaching process in the Milliken mill. Operational results for September, 1962, are presented, showing a uranium extraction of 95.5 per cent, with a saving of some 16 lbs. of 100 per cent H~S04 and some 9 lbs. of lime per ton milled. Methods for effecting further improvements in the process are indicated. HISTORY P RIOR to the incorporation of two-stage leaching, the process for the treatment of uranium ores at Milliken consisted of a single-stage sulphuric acid leach, followed by a solution recovery step involving washing in thickeners and two-stage filtration. The thickener overflow solution was subsequently concentrated and purified by ion exchange, and the uranium was recovered, by two-stage precipitation, as ammonium diuranate. Figure I illustrates this flowsheet. For satisfactory extraction of uranium from the. Milliken ore, a high residual acidity, of the order of 40 grams per litre of free acid in the discharge solution, must be

Jan 1, 1963

By B. F. Haanel

IN the fall of 1929, a paper was presented at the Annual Western Meeting of the Institute entitled The Fuel Research Laboratories at Ottawa and the Scope of Their Investigations. At that time, the equipment of the laboratories had not been completely installed, but the regular routine work was being carried on as usual, and several large-scale investigations were being conducted. It is now five years since that paper was presented, and it seems fitting that a brief description of the investigations which have been undertaken, together with results-especially those which have reference to western Canadian fuels-be presented at this Annual Western Meeting. The coal mining industry of western Canada has, within the past few years, suffered many unfortunate vicissitudes. The replacement of coals by oil, for bunkering ships, for operating railway locomotives, and for heating, has weighed heavily on the coal mining industry of British Columbia and Alberta generally, but more particularly in the Crowsnest Pass area and Vancouver-and hydro-electric developments have also left their impress. With a full appreciation of these conditions, the Department of Mines planned research and large-scale investigations which it was considered would be of the greatest benefit to the coal industry, and the results have amply justified the plans and anticipations. The fact, however, must not be lost sight of, that the application of the findings of certain of these investigations would not have been feasible had not the Federal Government assisted the transportation of coal by the application of railway subventions. These subventions permitted Canadian coals to compete at competitive points with United States coals, and it must be admitted also in this connection that certain of the collieries which have benefitted, both as a result of the railway subventions and the investigations conducted by the Fuel Research Laboratories of the Department of Mines, made special efforts to produce a coal which was capable of competing with the American product, by special preparation at the mines.

Jan 1, 1936

By A. F. Matheson

"Bankfield Consolidated Mines, Limited, and Tombill Gold Mines, Limited, in the Little Long Lac area, Ontario, mined an orebody that was common to both. The discovery' of this orebody was made by surface prospecting in May, 1932, on Bankfield ground, following an original discovery made in the same manner on the same property on a small reef in Magnet lake in October, 1931. The production from the two mines between 1937 and 1942 was approximately 135,000 oz. gold from about 420,000 tons of ore, an average grade of 0.32 oz. a ton. Production was nearly equally divided between the two properties. Both mines are now closed, the ore exhausted.""The ore is mainly sheared and fractured greywacke and porphyry impregnated by silica and small amounts of metallic minerals. To a lesser extent there are definite quartz veins in the ore zone""(l). The metallic minerals present were principally pyrite, arsenopyrite, pyrrhotite, and native gold .As at other mines in the Little Long Lac area, an elongated, broad, deep trough of folded, steeply dipping volcanic and sedimentary rocks, striking roughly east-west and surrounded by younger granite, is host to the orebodies of the Bankfield and Tombill. In the immediate area of the two mines iron formation and conglomerate bands occur nearby both north and south of an intrusion of porphyry-Cliorite, suggesting repetition of beds and folding. Although considerable drag folding is in evidence, folding on the above scale has neither been proved nor disproved."

Jan 1, 1954

By S. Qian

Galvanic corrosion is a potentially major concern associated with the application of stainless steel reinforcement which is in direct (electrical) contact with carbon steel reinforcement in concrete structures. Judicious use of stainless steel rebar in both new construction and rehabilitation of older structures is a viable, cost-effective option for extending service life and reducing maintenance costs. Questions, however, had arisen about the possibility of increased corrosion due to galvanic effects. This paper investigates the galvanic-coupling behaviours of three different types of stainless steel and carbon steel. Tests were performed both in electrochemical cells and with specimens in concrete inside an environmental chamber. The results show that oxygen reduction on stainless steel is the rate-determining factor for galvanic coupling of these two metals. It is much lower than that of passive carbon steel. As a result, the galvanic coupling of stainless steel with carbon steel will not increase the risk of corrosion of carbon steel reinforcement.

Jan 1, 2005

By K. Halada

Current trend of the global flow of strategic metals are analyzed to discuss the strategy of the development of recycling technology and alternative technology. In many cases, each global flow of metal is changing from the trilateral structure of U.S., EU and Japan in the later 20th century into the convergence to China as the factory of the world. Scrap flows are also changing dynamically. A long term change of prices of metal has gotten changed since the entrance of this century. The estimation of metal consumption up to 2050, in which the author estimated that many kinds of metal will overshoot the reserve base line, is revised considering these change of current trends.

Jan 1, 2014

By G. Barrasso

REACH was proposed by the EU Commission in October 2003 and stands for the Registration Evaluation, Authorisation and Restriction of Chemicals. It requires that all substances identified as persistent, bio-accumulative and toxic, whether the risk of those chemicals being released is real or perceived, require registration prior to them being allowed to be imported into the European Union. An internal investigation by the metals industry indicates that almost all primary raw materials streams would be classified as hazardous due to the potential health or environmental hazard properties of one or more of their ingredients. REACH uses a wide definition for chemicals and metals and as such its implications greatly impact the entire supply chain of the metals industry. The process of registration would require the producer/ importer to produce a dossier. Initiatives along the same lines as the EU REACH are also coming up in other parts of the world. REACH requires registration of at least four substances manufactured by the aluminium industry: aluminium metal, including powder, aluminium oxide, and aluminium hydroxide. The proposed legislation permits the affected companies to band together to form a consortium to develop certain aspects of the registration application. The aluminium industry has established a consortium and testing is currently underway.

Jan 1, 2006