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By Lloyd A. Clark

"The kuroko deposits, which are extremely variable in size, comprise both stratiform layers of clastic sulphide particles and cross-cutting vein and disseminated components. The ores lie on the flanks of rhyolitic lava domes which have risen from a postulated subvolcanic magma chamber that provided cupriferous hydrothermal solutions and also acted as a heat source driving ground-water convecting cells. The polymetallic sulphides precipitated initially in explosion craters, pipe fillings and feeder veins as rising hydrothermal solutions mixed with sea water. As sulphides clogged the plumbing system, minor phreatomagmatic explosions produced layers of sulphide fragments on the adjacent sea floor. One to ten repetitions of this process produced multiple fragmental sulphide beds. Each deposit formed in a relatively short space of time, because only minor tuff beds are intercalated in spite of active volcanicity in the region. In this model, the heated ground waters convecting through thick piles of acidic pyroclastic rocks leach the zinc, lead and barium later deposited as kuroko ores. As the subvolcanic pluton cools, the supply of silica and copper wanes and the minor counter-circulation cells above the pluton are replaced by main cell fluids bearing zinc, etc. This change in solution flow is abrupt rather than gradual, as the plumbing system is somewhat disrupted by the magmatophreatic explosions that create each ore layer.IntroductionKnowledge of the kuroko deposits ha s greatly expanded during the 25 years since modern recognition of their volcanogenic origin. However, one aspect of the ore s, which may be of unique importance in their genesis, has received little attention. That is the fragmental character of much o f the sulphide ore, which was briefly referred to in a previous publication (Clark, 1971) and is examined in more detail by Barton (1978). Most researcher s have concentrated their attention on or e deposition above and beyond the vent, which is inconsistent with the geology."

Jan 1, 1983

By F. O. Verret, A. McKen, G. Chiasson

Several grindability tests were developed over the years to design grinding circuits or optimize existing operations. Each test has its own strengths and weaknesses and it is imperative to select the proper test procedure(s) to meet project deliverables and minimize the risk of a project. Pilot plant testing of large bulk samples historically constituted the traditional approach for AG or SAG design, but was gradually replaced by small-scale tests. Nowadays, conducting grindability tests requiring only a few kilos of material on several samples is a more typical approach to grinding mill design. This paper summarises the requirements and deliverables of various bench-scale test procedures, their strengths and weaknesses, and cases where AG/SAG pilot testing should still be performed.

Jan 1, 2012

By C. P. Verschuren, P. W. Kingston, W. F. Caley

"In recent years, there has been rapid growth in the use of natural stone building and construct ion products. The largest growing markets are for pre-fabricated natural stone panels for interior and exterior wall facing and flooring. This increased demand is attributed to advanced quarrying and processing technologies, renewed appreciation for the aesthetic appeal of natural stone, and to the superior durability of natural stone when compared to glass, steel, and concrete. Geologically, plutonic rocks, and to a lesser extent marble and limestone/dolostone, are used extensively for these applications. This paper details the economic structure of the dimension stone industry, describes the necessary characteristics of a stone quarry, and outlines the geological criteria which favour an economic quarry.INTRODUCTIONThe world building stone industry has remained relatively stable over the last 5 to 6 years. In contrast, the North American stone industry has experienced substantial growth during that period. The increased use of commercial granite is primarily responsible for this growth, where use as exterior wall veneer for commercial, industrial, and institutional buildings represents the largest and fastest growing market.This increased usage in the construction industry has been sparked by the application of new technologies in quarrying, processing and installation , ma king natural stone more competitive with man-made materials which are energy intensive to produce, and have risen dramatically in price. The development of safer, time-saving stone installation techniques has also appealed to the liability-conscience construction industry. Finally, there is a trend by designers and architects toward utilizing long-la sting weather-resistant building materials, and a renewed appreciation of the aesthetic appeal of natural stone. The other large user of granite is the monument industry of North America which, although it has decreased slightly in recent years, still consumes approximately 40% of all commercial granite produced. The local use of commercial marble has remained relatively stable, and North America still relies heavily on European sources and suppliers. There has been some concern over the use of marble for exterior applications in areas subject to acid rain, and in colder climates where the marble ma y be vulnerable to freeze thaw cycles. Despite these concerns, the greatest problem is not with the structural breakdown of marble but the inability of some marbles to retain their polished finishes in the se environments. As a result, there has been an increase in the use of granite at the expense of marble for exterior applications. Finally, commercial marble is used extensively for interior flooring, wall s, counter tops, furniture, sculptures, and stairway components"

Jan 1, 1989

By Changyoon Kim

Technological advances in mobile systems, such as smartphones and tablet computers, provide engineers with new opportunities to enhance the current facility management processes. Equipped with powerful system processors, touch screens, and wireless communication capabilities, mobile systems enable the experience of omnipresence of facility information. Building information modeling (BIM) also enables improvements in facility management. With an advanced data structure and visualization capacity, BIM can be used in numerous applications for facility management. This study aims to incorporate the strength of mobile systems and BIM in facility management. The proposed system, which utilizes smartphone technology, allows engineers to conduct facility management functions, such as maintenance planning, inspection, and assessment, irrespective of a user?s location. The integration of building information modeling in a system provides detailed visual information of the building components. A case study was conducted to verify the applicability of the mobile system in terms of the hardware functions, system design, and user interface. This proposed system, with its study results, provides a guideline as to how mobile systems can be effectively integrated with BIM for improved management of facility information.

Aug 1, 2013

By A. M. Brown, P. V. Straznicky

Dimpling as a means of flush countersinking rivets is an old process predominantly used in secondary structures. The introduction of GLARE as an aerospace material has renewed interest in dimpling and its possible application in primary structures. The dimpling process is able to prevent the creation of a machined knife-edge in the thin aluminum plies of the GLARE sheets. In addition, dimpling eliminates the need to use reduced height rivets, such as the NAS 1097 rivet style. This investigation expands on an earlier study into dimpling of GLARE by Rans and Straznicky. In order to tailor the dimpling process to GLARE, FEM simulations were developed. After verification, a study was performed to find the best parameters for dimpling GLARE3-2/l. Coupon fatigue tests were carried out and the dimpled joints demonstrated increased fatigue lives over the conventional machine countersunk joints. Future wide panel fatigue tests are planned to confirm the usefulness of dimpling thin GLARE laminates.

Jan 1, 2006

By Yoginder P. Chugh

Beginning in 2010, a scientifically-founded water spray system for continuous miners (CMs) has been in development at Southern Illinois University that significantly reduces respirable dust exposure for workers in the face area (patent pending). It includes engineered sprays around the cutting drum, outer bitring sprays, chassis sprays and side cutter boom sprays. About 3.6?4.5 m behind these sprays are additional sprays that cover the area between the CM chassis and the mine roof and ribs. The innovative spray system uses approximately the same volume of water as spray systems currently used on CMs and with similar operating pressures. The innovative spray system design also takes into consideration coal dust wettability. An Illinois mine decided to implement these concepts on a CM during the rebuild stage. Dust control performance of the rebuilt CM was evaluated using gravimetric dust sampling and real-time monitoring with multiple personal dust monitors. The average results based on gravimetric sampling of about 105 cuts show about 30 and 20% reduction in dust exposure for the miner operator and the haulage unit operator, respectively. Visibility in the mining areas was also significantly improved. Since the initial demonstration, the coal company has implemented the system on all of their operating CMs.

Aug 1, 2013

By Eric R. Skonberg

"Technology exists today to blind drill a mine shaft 20 feet in diameter, unlined, over 3,000 feet deep. These shafts must be lined in the most economical, safe and expedient manner possible. A new technique of stacking precast concrete cylindrical sections in the unlined shaft has been developed to yield a dry and hydrostatically lined shaft .These sections must withstand an external radial pressure of 3,000 feet of water yet take up as little room as possible in the shaft . Using high-strength concrete, wall thicknesses may be kept at 2 feet. The outside diameter of the sections has been chosen to be 18 feet to allow for some annular space between the liner and shaft wall. The concrete sections are produced in segments 10 feet long weighing 75 tons each. During drilling operations, the concrete sections are cast and cured. After drilling operations are complete, a headframe is situated over the shaft. The unlined shaft remains full of fluid. A special liner running tool is mated with the section in three steel ports at the bottom of the section. The section and running tool are lowered into the hole, and the tool is disconnected and returned to the surface. Subsequent sections are lowered and stacked using the same operation. Grout is placed behind the liner to result in a dry shaft."

Jan 1, 1981

By H. Ikeman

"The highly specialized communication systems used in the mining industry place exacting demands on equipment and transmission media. Safely and reliability of services are perhaps the two most important factors. Fibre optics is ideally suited 10 meet these stringent requirements. Aside from being an intrinsically safe, non-sparking and EMI/RFI immune medium , fibre optics offers greater reliability , higher quality of services and superior flexibility over conventional copper or radio-based communication systems.This paper wilt show how fibre optics can be applied in mining industry applications. Emerging trends and concepts will be presented to show how fibre-optic-based integrated service communication networks and local distribution systems can be implemented.IntroductionCommunication requirements in today's mine s are varied and extensive. The communication system must be rugged , safe and reliable, yet provide an ever increasing amount of high quality services. Presently, these systems are implemented using conventional copper cable. As mining method s and technology advance and the demand for better and more communication services increases, traditional systems quickly reach their limitations. It is under these circumstances that we turn to fibre optic communication systems.Fibre optics is a mature technology which is finding its way into more and more applications worldwide. A fibre optic communication system can provide a level of performance unattainable by conventional cable systems yet ca n be cost competitive. As is well known, fibre optics provides a noise-free, noise-immune, high -capacity communications channel. Glass fibre, being dielectric and non-sparking, is an intrinsically safe communications medium. Clearly, it is ideally suited to the harsh environment present in a mine.From a communication systems point-of-view, the topology of a deep mine is unique. The objective of the systems engineer is to implement a total communications capability throughout this wide spread area. Ideally all classes of services should be accessible throughout the network-an integrated network concept. Recent advances in communications technology combined with fibre optics make this realizable."

Jan 1, 1984

By J. C. Thornley, H. L. J. Drummond

"Fifty years of wear on the original carbon steel shaft of this hydro turbine necessitated repair operations in 1980. Both austenitic and martensitic stainless steels have been used individually as journal materials in separate trials on an80-inch long and 22-inch diameter radial bearing but neither one nor the other has been successful.The wear and cracking problems of the stainless steels leading to the present abandonment of both classes of stainless steel are described. In particular the dependence of the toughness of type 410 stainless steel on its tempering temperature and the susceptibility of that steel to quench cracking are highlighted because problems have been caused by both of these metallurgical factors.IntroductionAs part of a desire to improve the efficiency of a fifty-year old hydro-electric generating station on the Saint John River, the decision was made to change the journal and bearing material for the shaft bearings, which are stave-type bearings. For the initial fifty years of operation the bearings had been wooden (lignum vitae) and had run on the carbon steel shaft directly. For one of the four unit s at this station the performance of this combination has been truly excellent, and the remaining three sets of bearings had performed well. However there had been shaft wear on the units and the wear had made the shafts somewhat elliptical when a decision was made to install some sort of new journal on to three of the old shafts. [In addition to the wear on the carbon steel journals it was found that one shaft was significantly softer in the bearing area than it was immediately above the bearings (180 Vickers in comparison with 230 to 250 Vickers)] ."

Jan 1, 1985

By Robert B. Parsons

"The budget that was tabled by Finance Minister MacEachen on November 12, 1981 will result in a major tax reform of Canada's income and sales tax systems, the likes of which have not been witnessed by taxpayers since 1971. All segments of the economy will be affected one way or another by the far-reaching budget proposals; the mining industry did not escape untouched.Important changes will be introduced which will alter some of the fundamentals of structuring mineral resource ventures in Canada. This month, Tax Notes examines these changes, and also summarizes the other highlights of this key federal budget.IntroductionFinance Minister MacEachen's budget, with its lower personal tax rates, loophole plugging and tax shelter bashing, represents the biggest shakeup in our tax system since tax reform in 1971. In his budget, presented in the House of Commons on November 12, Mr. MacEachen proposed substantially lower tax rates for middle and upper income individuals, with the top federal and provincial tax rate dropping to about 50%, but in return he eliminated most of the opportunities for individuals, and corporations, to reduce or defer taxes through a wide variety of tax shelter and tax planning mechanisms.Although many of those budget proposals that dealt with the resource industries focused on the implementation of the September 1, 1981 agreement reached by the federal and Alberta governments concerning the National Energy Program (see Tax Notes in the December 1981 issue of the Bulletin), the budget also contained some proposed amendments that would have significant implications for investment in the mining industry.This month, Tax Notes examines these latter proposals, and also summarizes very briefly those budget proposals which are not unique to the resource sector."

Jan 1, 1982

By Matthew S. Bingham, David H. Searle

"One of the most significant developments in environmental law has been the development of mandatory project review processes, at both the federal and provincial levels.FederalWhile, in the past, project review processes have, f or the most part, been spelled out in guidelines, the guidelines have not had the force of law. All that has changed, particularly at the federal level, with the Federal Court decisions commonly referred to as the Old Man River and Alameda and Rafferty Dam cases. These decisions, taken as a whole, are authority for the proposition that the Environmental Assessment and Review Process Guidelines Order, SOR 82-487 is a law of general application, not a mere guideline which may or may not be applied. This federal environmental assessment process first provides for a screening, and, depending upon the results of the screening process, the possibility of a public review. This federal process only applies, however, when the proposal is being undertaken by a federal department, or where the Government of Canada makes a financial contribution, or where federal lands are involved, or where a federal licence or permit is required.Bill C-78, the Canadian Environmental Assessment Act, will replace the Federal Environmental Assessment and Review Process Guidelines Order once it has been passed by Parliament. Currently the bill is being widely discussed, both between governments as well as public interest groups.ProvincialOn the provincial scene, there are three project review processes, one concerned with new mines, the second with energy projects and the third with all other major projects. The most recent initiatives taken by British Columbia are twofold. First, the Mine Development Review Process which was in the form of a guideline, has been replaced by the Mine Development Assessment Act. Second, the Major Project Review Process has been formulated and is to apply to four main categories of major projects:1. Pulp and paper production;2. Mineral smelting and refining;3. Chemical products; and4. Major ports and marinas.Energy projects are governed by the Energy Project Review Process which is legislatively mandated under the Utilities Commission Act."

Jan 1, 1991

By Alfred W. G. Wilson

MR. F. E. LATHE: In studying any subject whatever, one should at least occasionally stand back from the canvas, as it were, and take a broad view of the picture. It is such a view of the subject of industrial minerals that Dr. Wilson has given us today, and, in consideration of our efforts to utilize Canada's resources to the utmost in the present emergency, it seems most timely. I shall confine my remarks on the subject to the resources of the atmosphere and hydrosphere. We seldom stop to realize our dependence upon the atmosphere, not merely as a source of the oxygen we breathe but also of other indispensable elements. As recently as the beginning of the present century, grave concern was felt lest the rapidly increasing population of the world should ultimately starve for lack of the nitrogen required for crop growth. I recently noticed a reference to the Scientific American for March, 1890-just fifty years ago-in which an account is given of work on the fixation of nitrogen, which, said the article, "leads to the conclusion that while cyanides and ammonia may be thus produced experimentally, there are as yet insuperable difficulties in the way of adapting those methods to industrial purposes". Y et, in the early part of the present century, the development of the arc, cyanamide, and synthetic ammonia processes of nitrogen fixation was such as to remove, for all time to come the possibility of a shortage of nitrogen. Today, the atmosphere is by far our greatest source of nitrogen, and the capacity of the nitrogen fixation plants of the world is at least 4,000,000 tons annually-much more than can at present be utilized. Pure oxygen or oxygen-enriched air offers great possibilities in metallurgy and industrial chemistry, but, so far, little application has been made. In a paper presented to the Institute in 1926, 1 pointed out the theoretical savings which could be effected by the use of oxygen in burning carbon-when the gases pass off at 2,460°F., the fuel saving is no less than 50 percent. The use of oxygen on a commercial scale is intimately tied up with the question of refractories, but we should not forget that the possible changes in metallurgical practice by the use of oxygen are truly of revolutionary character.

Jan 1, 1940

By Yve Aymong

"The objective of this paper is to help readers benefit from the practical experience of persons who have been engaged for several year s in the testing and repair of power transformers. Power transformers are known to be reliable pieces of equipment with expected usage of 25 to 30 years, but simple problems such as leaking radiators, or a bad contact on a tap changer, could shorten the life of a transformer. To ensure a longer life span, transformers should be checked on a regular basis.What is a Power Transformer?It can be a 90 MVA transformer for Hydro-Québec or a power transformer can be a 500 KVA unit in a small hospital. Generally a power transformer is an oil -filled type of 3 to 5 MVA. It can also be a dry type transformer, that should be treated in the same manner as oil-filled transformers, and some of the tests explained in this paper also apply."

Jan 1, 1984

By R. P. Viljoen, A. L. Sokolov

"The distribution of mineralized provinces is analyzed on the basis of their genetic link with specific blocks of the earth's crust including ancient platforms, mobile belts and zones of tectonicmagmatic activation. Mobile and fold belts surround the Siberian platform in Russia and the Kaapvaal craton in South Africa, with decreasing age zoning away from ancient platform margins. The main differences in the geological development of the two cratonic areas are: (1) the long period before the final stabilization of the Siberian platform (3600 Ma to 1600 Ma) and the comparatively short period of time for the stabilization of the Kaapvaal craton (3600 Ma to 3050 Ma) and (2) the intensive multiple activation of the marginal zones of the Siberian platform and the tectonicallycontrolled, magmatic sedimentary, intracratonic activity, typical of the Kaapvaal craton. Mineralization of the Siberian platform is largely characterized by marginal reactivation zones of differing ages although mineralized intracratonic Cu-bearing basins of Proterozoic age are also known. Mineralization of the Kaapvaal craton is mainly related to the formation of the intracratonic basins i.e., Witwatersrand (Au, U) and Transvaal (Au). The latter is characterized by multi-age volcanic-intrusive activity including the emplacement of Bushveld Complex (Cu, Ni, Pt, Cr, Au, V). The Siberian platform is characterized by the prolonged development of inherited mineralization from Archean until the late Mesozoic. The main period of mineralization in the Kaapvaal craton is restricted to the middle Proterozoic.The Baykal-Patomskaya and Namaqua-Natal mobile zones occupy similar positions adjacent to the Siberian and Kaapvaal cratons, respectively, and demonstrate similar modes of metallogenic development: i.e., the early formation of exhalative Pb-Zn-Cu deposits during the early stage and magmatic Cu deposits during the late stage. The more remote mobile belt near the Siberian platform, the Trans-Baykal, is characterized by intensive multi-age mineralization (Wo, Mo, Sn, fluorite), related to a period of tectonic-magmatic activation. The Saldania Belt occupies a similar position near the Kaapvaal craton but is known for its poor Au, and Cu mineralization. It does, however, have some similarities with Trans-Baykal Belt in regard to Mo-W bearing granitoids.The phenomenon of interference of geosynclinal, orogenic, platform, and tectono-magmatic activation regimes is known for the Russian section of the Pacific Ocean Volcanic Belt."

Jan 1, 1994

By H. E. Wilde

"Zinc has been used for many years as a galvanic coating for the protection of steel. Electrochemical measurements show that zinc actually overprotects steel. The corrosion rate of DQSK (drawing quality semi-killed) steel in air saturated salt water was determined as a Junction of applied cathodic potential. The resulting data indicate that at a critical cathodic over potential of - O. 725 Vsce an acceptably low corrosion rate of less than 1 mpy occurs. Using the developed criterion, alloys of Zn/X and AL/X were produced and evaluated in galvanic contact with steel in a standard laboratory test. The results indicate that Zn /Mn, Zn /Co, AI/Mg/Si and AI/Mg/Ge alloys offer excellent galvanic protection along with (a) no hydrogen evolution, and (b) improved dissolution life over Zn coatings.IntroductionZinc coated (galvanized) steel has been successfully used in applications where bare (or painted non-galvanized) steel would suffer corrosive attack. In general, galvanic coupling to zinc, as either an anode or a coating, is an effective means for combatting steel corrosion. Because of this, the use of galvanized steel has increased markedly, stimulated primarily by automobile manufacurers seeking to extend the corrosion warranties on automobiles(1).Although effective, zinc coatings are not without a number of drawbacks which warrant efforts to improve them. For example, because of the widely differing electrode potentials between zinc and steel ( - 1.05 Vsce and - 0.60 Vscc, respectively, in air saturated NaCl solutions), the zinc corrodes at a rapid rate to protect the steel. This is reflected in the limited lifetimes of galvanized unpainted siding. The basic electrochemistry controlling the situation is shown in Figure 1, for a system controlled by oxygen reduction. The zinc corrodes sacrificially to protect the steel, while cathodically polarizing the steel to a potential near that of zinc's open circuit anode potential."

Jan 1, 1990

By Roger D. Plouffe

In today's mining industry, it is possible to retrieve, from small-diameter holes, geophysical data for qualitative interpretation in exploration and quantitative interpretation in the development of orebodies. The primary objectives in the exploration stage are to identify where, within a hole, economic minerals are, and to help in lithological interpretations. Other aspects, which are more quantitative, are the interpretation of downhole logs for parameters which can be used in surface geophysical methods (i.e. density for gravity surveys, acoustic velocities for seismic surveys, and magnetic susceptibility for airborne and ground magnetic surveys). Recent advances in equipment design, portability and durability have made downhole logging in exploration more inexpensive and reliable. This new equipment is being used to generate very precise quantitative results. This is especially true on uranium development projects. The interpretation of gamma logs for eUJOS values has finally become precise enough that they have begun to replace chemical values in reserve calculations. Another part of development data is density and equilibrium information, which, with today's technology, is being derived from downhole probing. In the years to come, the trends for many metals are toward neutron activation techniques, or "in-situ assaying", and the use of multiple logs for better lithological and physical rock property determinations.

Jan 1, 1981

By N. R. Thornton

This paper discusses the rapid growth in the application of instrumentation for metallurgical process control. It covers such methods as ultrasonics, pulp density measurements, on-stream X-ray analysis and reagent control, as well as the expanding use of computer control and data acquisition.

Jan 1, 1971

By Farid Mirahadi

Forecasting productivity of construction operations is a difficult but crucial task in planning construction projects. Over the past decades, many models have been developed to forecast productivity for different construction operations. Models made up of several functional relations and controlled by a specific number of control rules are more in line with human reasoning and logic. Neural-Network-Driven Fuzzy Reasoning (NNDFR) structure as one of these models shows a great performance for modeling datasets among which clear clusters are recognizable. Lack of the compatibility of conventional NNDFR with fuzzy clustering algorithms besides the insufficient attention paid to the optimization of number of clusters in this model, created a potential area for further research. The main contribution of the proposed model is to develop a modified NNDFR system to model construction data. To this end, Fuzzy C-Means (FCM) algorithm is substituted for K-means in NNDFR structure, and its parameters such as the number of clusters and weighting exponent are optimized through genetic algorithm. The proposed model is further verified through simulation of a construction operation in which several qualitative and quantitative factors are considered. Its implementation to the case study shows a considerable improvement of model performance with lower Mean Squared Error (MSE). The developed model assists researchers and practitioners in utilizing historical construction data to forecast productivity of construction operations with a high accuracy that could not be obtained by traditional techniques.

Aug 1, 2013

By A. Vervoort, A. Govaerts

Geostatistical concepts are often difficult for students to understand, even those with a strong mathematical background. One of the main problems is the link between the variation of the parameter value in space or time and the calculated experimental semivariogram. Another challenge is differentiating between directional and omnidirectional semivariograms and their interpretation. For these reasons, interactive tools were developed based on the free public domain software R. The use of these interactive tools is limited to educational situations only (i.e., to visualize basic concepts). The interactive modules can be accessed at www.bwk.kuleuven.be/geostatistics.

Jan 1, 2014

"In flotation research, relatively little attention has been paid to understanding particle-bubble detachment phenomena compared with attachment processes. With CFD models now incorporating attachment/detachment kinetics, it is important to obtain more accurate formulations for detachment probability. The formula most often used is due to Bloom and Heindel (2002) who proposed that the rate of detachment would equal the product of detachment frequency, as previously estimated by other authors, and probability of destabilization, as estimated previously by Schulze. These two factors both account for the balance between stabilization and destabilization forces, so the product accounts for this effect twice. An integrated procedure has been followed to estimate the overall detachment rate by re-analysing the process. In this analysis, detachment rate is calculated as the frequency of eddy-aggregate interactions (or “collisions”) sufficiently energetic to cause detachment. The Bond number analysis of Schulze has been incorporated into the turbulence frequency analysis of previous authors in an integrated way. The new formulation has essentially the same type of dependencies as the previous model, but gives a lower detachment frequency. Detachment frequency has been calculated using the new formula for conditions relevant to an industrial flotation cell. INTRODUCTIONIt is well known that the effectiveness of froth flotation for separating different minerals is limited to the particle size range of approximately 10–100 mm (Trahar & Warren, 1976; Trahar, 1981). Fine particles tend to follow fluid streamlines around bubbles limiting the likelihood of bubble–particle collision, while coarse particles can be more easily detached from bubbles before collection can be achieved.Phenomenological models have been developed to quantify the physico-chemical aspects of flotation in order to better understand factors affecting these limitations, and to suggest ways of broadening the window of feasible flotation. Koh and Schwarz (2008) have incorporated these models into computational fluid dynamics (CFD) models of flotation cells, which have then been used for design and scale-up purposes (Schwarz et al., 2015). The models are based on dividing the process of bubble–particle interaction into three subprocesses: collision, adhesion and detachment. Of these, the hydrodynamics of bubble–particle collision and the probability of adhesion have been studied most extensively, while the dynamics of detachment have received relatively little attention from investigators."

Jan 1, 2016