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By M. J. Nicol, T. Moyo

Ammoniacal solutions are an effective lixiviant for the oxidative dissolution of some mineral sulphides. A detailed study of the anodic dissolution of chalcopyrite in ammonium sulphate-ammonium hydroxide solutions has been carried out using cyclic voltammetry, chrono-amperometry and rest potential measurements. The role of the copper(II)/copper(I) redox couple in the oxidation process has been evaluated. Rest potentials have been found not to be affected by oxygen but to increase with an increase in initial copper(II) concentration. Pseudo-steady-state anodic current densities measured in the absence of copper(II) ions at the rest potentials obtained in the presence of copper(II) ions increase with increasing concentration of copper(II) ions, confirming the positive effect of copper(II) ions on the rate of dissolution of the mineral. Cyclic voltametric and chrono-amperometric data show that in the absence of initial copper(II) ions, the rate of dissolution in the presence of dissolved oxygen is significantly lower. These results confirm that the effective oxidant for the mineral under the conditions of the study is copper(II) and not dissolved oxygen. Coulometric measurements have been used to establish the stoichiometry of the anodic reaction at different potentials.

Jan 1, 2014

By A. G. Roach

MILLING of Nova Scotia gold ores began in 1862 with arrastras and wooden stamps and has progressed to heavier stamps followed by tables and other forms of concentration for the recovery of the sulphides. Chlorination and cyanide leaching of the concentrates has been practised, and in 1936 the combined amalgamation and all-sliming cyanidation plant of Seal Harbor Gold Mines was built. It has since been found that it is not necessary to cyanide the full tonnage and now only the concentrates are being so treated. From his experience in this enterprise, the writer presents the accompanying flow-sheet and supporting comments. While he has not the temerity to maintain that it is the best or only flow-sheet for Nova Scotia gold ores, he feels that it warrants thoughtful consideration by members of the milling fraternity of the Province. THE ORE The gold in Nova Scotia ores occurs both free and intimately associated with sulphides-chiefly arsenopyrite. Much of the free gold is quite coarse and crystalline. This is especially true when it occurs in white quartz. When in the slate, it is usually in thin plates and scales, frequently coated and discoloured. The values bound up in the sulphides are not amenable to amalgamation and must be recovered by other methods-concentration, followed by smelting or fine grinding and cyanidation. While high freight and treatment charges apply on concentrates shipped from the Province to smelters, a considerable quantity has been so disposed of in the past. However, it is hoped that a customs cyanidation plant will soon become available to producers of these auriferous concentrates in Nova Scotia.

Jan 1, 1938

By G. M. Behrend

A group of mining men attending a recent workshop on "Analysis and Control in the Canadian Minerals Industry" issued, among others, the following statement: "Slurry flow measurement is considered to be one of the most inaccurate in the industry. A special program should be launched to encourage development." In response, this paper starts off the program with an investigation of the principles and the conventional practice of slurry flow measurement and identifies weaknesses which cause inaccuracies. Then it follows with descriptions of nonconventional systems in use at various locations and comments on their degree of success. The paper concludes that relatively simple methods, which it describes, can be applied to obtain an accurate slurry flow measurement.

Jan 1, 1973

By R. D. Corrans

"Abstract - Africa is endowed with a number of the world's giant ore deposits which have contributed significantly to the development of their host countries. Mineral exploration has a long history in the continent, but mining on an unprecedented scale took off during the latter part of the 19th century, accompanied by the development of lines of communication and other infrastructure to service the major mining centres .The ""Winds of Change"" which swept Africa in the 1950s and 1960s brought in new styles of government and economic management to a number of regions, often with demise of economic viability and infrastructure. ln recent years, with the end of the cold war, collapse of communism and changes in South Africa, new opportunities for mineral exploration are opening up rapidly in Africa. However, due to the large cost, long lead-in time, and high risk of developing new mineral ventures in the continent, it is necessary for the host countries to draft realistic and favorable mineral laws and fiscal codes in order to attract, and not deter, potential mineral investors.There will be an on-going role in mineral exploration throughout Africa for the artisanal miner, the smaller entrepreneurs and mining companies, exploration aid programs funded by the developed countries through African governments, as well as the major mining houses who have the resources to develop larger viable mineral deposits."

Jan 1, 1994

By G. Shore

"The development of a DC resistivity instrumentation system for data acquisition in extreme topography yielded an unexpected bonus in the quality and information content of the type of raw data gathered. Not only were traditionally too-rough areas being investigated systematically for the first time, the unique high-density, multi-directional raw data were providing the opportunity to greatly expand the range of conductive and resistive signatures that could be accurately recognized. Using a true 3-D inversion algorithm, 3-D earth resistivity imagery began to show distinctive anomaly patterns for hydrothermal mineralization at the seldom-visited resistive end of the spectrum, successfully imaging epithermal gold systems in conditions that had defied conventional ground and airborne geophysics for years.The traditional mode of designing a resistivity survey to test a specific target concept was shown to be an unnecessary limitation on exploration thinking when a single sweep acquisition of dense, multi-directional 3-D raw data could effectively provide the all-targets “shotgun” coverage that would take 10 or 12 conventional surveys to duplicate. Exploration planning has the opportunity to move from single steps of trial and error geophysical testing to a mode of mapping everything at the outset, and then sorting out what might be of exploration interest in the results. Survey parameterization becomes the non-technical process of marking an outline on a map and declaring “survey here.” Operational and interpretational reasons for not testing where the exploration interest lies have all but disappeared. With any-terrain capabilities and unprecedented raw data density and overlap to support interpretation of complex conditions, that outline can be drawn through extreme rough terrain, including lakes, cliffs, industrial facilities, and grounded installations to test for generally unknown sub-surface features of potential interest.As more is learned about the larger-scale signatures of ore settings and the district-scale geo-electric imprint of hydrothermal processes on lithology, it appears that the only thing certain about ore signatures is their uncertainty. This is not bad news. New opportunities abound as the advanced 3-D technology allows a first effective look at the previously unexplorable rough terrain or complicated settings, and a second look at areas where older results may now be known to be non-definitive."

Jan 1, 2002

By M. J. Lopatka

This paper presents the results of field test and theoretical analysis driving resistance articulated 4x4 tracked robot test-bed. Tests were made on four different grounds. Designated elastomeric tracks resistance coefficients are much higher than for steel tracks. This information was important for the proper estimation of energy consumption in the process of driving.

Aug 1, 2013

By K. van Netten, T. P. Ernst

"Froth flotation has been used successfully for about a century in the beneficiation of both coal and mineral particles. With the on-going trend towards lower feed grades, however, there is a need to transform this technology in ways that can deliver ultrafast separations, with strong selectivity, and recovery, covering a broader size range. It should be recognised that the hydrophobic effect, with its highly selective and long-range interactions, will most likely underpin any new technology. We identified the separation of the concentrate from the tailings as the rate determining step of conventional flotation technology. This limitation was then addressed by developing a novel flotation technology, insuring the formation of a concentrate that could be separated more rapidly from the tailings. We introduced a novel binder medium, a highly concentrated water in oil emulsion, to act as the focal point for hydrophobic adhesion, effectively replacing the air bubbles used in conventional flotation. The hydrophobic particles adhere to and become embedded within the binder, forming saturated agglomerates that float upwards. Moreover, by forming these large and resilient agglomerates, the product can be quickly dewatered over a screen and separated almost immediately from the tailings. Remarkably, this new binder permits residence times in the order of a few seconds under batch conditions. This paper examines the performance of the technology as a function of the oil wt% added to the slurry. The paper also examines the performance of the technology as a function of the particle size, showing a decline as the particle size exceeds 0.50 mm.INTRODUCTIONFroth flotation involves the collision and adhesion of hydrophobic particles to rising air bubbles, the carrying of those particles from the bubbly-pulp zone into a froth zone, and subsequent drainage and migration of the pulp to achieve the final concentrate (Wills, 2006). Within a Jameson Cell the feed slurry and air bubbles are brought into intense contact within the active area of the downcomer, achieving rapid kinetics of hydrophobic particle adhesion to the air bubbles (Harbort et al., 1994). However, once the bubble laden product and tailings emerge from the downcomer there is the need for separation of the concentrate from the tailings, an inherently slower process. In other devices such as mechanical cells the initial kinetics of particle adhesion are far slower, relying on the turbulent eddies throughout the cell, while in a column the kinetics rely upon an even slower process of bubble interception with suspended and settling particles (Gorain, 2007). However, in all cases the driving force for segregating the bubbles from the tailings, and the drainage of the froth are inherently the same. We do note, however, recent advances by Galvin and co-workers in achieving so-called Fast Flotation, utilizing a system of inclined channels to dramatically increase the segregation rate of bubbles from the tailings, permitting much higher gas and feed fluxes to be applied, achieving up to a ten-fold throughput advantage (Dickinson et al., 2014). Any further improvement within the existing flotation paradigm would require the introduction of centrifugal forces, but this would also require the formation of much finer bubbles than is typically used given the tendency of relatively large bubbles to reach a limiting slip velocity due to deformations and increased drag. Across all flotation devices we argue the rate determining step remains the segregation of the bubbles from the tailings."

Jan 1, 2016

By E. Allen

Quebec Cartier Mining Company operates approximately two hundred and fifty pieces of equipment in a climate with a temperature that has averaged 27.5°F during the last seven years. The use of special-purpose lubricants, fuels, antifreeze, rubber compounds, and alloy steels have reduced the cold-weather hazards. In some areas, high-cost cold-weather protective heating devices are being eliminated with experience.

Jan 1, 1966

By Robert M. Vadas

Special considerations are described as they apply to the design of ring gears for high-power grinding mills. AGMA requirements, the importance of the supporting structure, material selection and related field experience are discussed, with special emphasis on available and developing manufacturing technologies.

Jan 1, 1978

By Rodney A. Cooper

The Mary River iron ore deposits were discovered in the 1960?s. The high quality of the deposits was immediately evident, and drilling programs were successful in defining a resource adequate for supporting a feasibility study. Through a combination of ownership, market and political forces, the deposits were not developed. Having missed the window of opportunity, the project remained dormant for over three decades. Baffinland Iron Mines Corporation, with its 100% ownership of the Mary River deposits, began trading publicly in 2004. Modern exploration and metallurgical test work began in 2004 and has continued in 2005 and 2006, resulting in total expenditures during this period of almost C$60 million. In May 2006, an engineering team lead by Aker Kvaerner E&C, a division of Aker Kvaerner Canada Inc., completed a scoping study based on the first of five identified deposits. Highlights of that study include direct shipping of high quality lump ore to Europe over a 34 year mine life at a production rate of 10 million tonnes per annum, based on an indicated resource of 309 million tonnes at 66.1% Fe and an inferred resource of 28 million tonnes at 65.9% Fe. Capital costs were estimated at C$1.5 billion. Using iron ore prices approximately 36% below that of the 2006 market, a pre-tax internal rate of return of 15% was estimated assuming equity financing. Payback on initial capital was 5.9 years. The pre-tax life-of-mine cash flow was estimated to be C$6.3 billion. As a result of this study, Baffinland initiated a Definitive Feasibility Study, under the management of Aker Kvaerner, which is scheduled for completion in December 2007. This paper touches on the geology of the deposits, the current resource and the outlook for expansion. Project permitting, construction planning, logistical challenges and ocean shipping considerations are discussed, providing a current perspective on the project scale, scope and timeline for commercial production. In addition, an overview of the Company?s bulk sampling program will be provided.

May 1, 2007

By S. Ando

The fatigue crack growth behavior of magnesium single crystal has been investigated, CT (compact tension) type specimens with different notch orientations were prepared. In the case of notch plane and direction are (1-210) and [10-10], fatigue crack propagates parallel to notch, From TEM observation, it is found that pyramial slips occures at the crack tip. When notch is normal to basal plane, a fatigue crack propagates [0001] and parallel to basal plane depending on stress intensity factor range, In the case of notch parallel to basal plane, a fatigue crack propagates through straight route with some {10-12} twin, Fatigue crack growth rate, da/dN of A- and B- specimen is lower than F-specimen with crack parallel to basal plane.

Jan 1, 2004

By Marlin E. Sandlin

NORTH-CENTRAL United States is now, and will continue to be, a natural market for Canadian crude oil. This area is a natural market for many basic reasons. There are no physical barriers along the border of our countries. This market is in dose proximity to Canadian production. This market is already joined by crude oil pipe-1,ines to numerous producing areas of Canada. The tariff barriers are reasonable. We are not handicapped by mandatory quota restrictions. There are many of us who desire lo sell Canadian crude oil in this market. Further, and what is really important, there are many of us who desire to buy Canadian crude oil for this market. It is fundamental that for crude oil to be sold in the world market, it must ?be sold at competitive prices. At the same time, it is important that such competitive price must result in a fair price for the crude oil at the we1lhead. The factors of nearness to market, cheap pipe line transportation, and reasonable United States tariffs, all tend to make ?possible a competitive market and a fair wellhead price.

Jan 1, 1958

By A. Moyano

The development of the traditional converting process performed in a PeirceSmith or Hoboken converter is limited by the investment magnitude associated to the fulfillment of the environmental regulations. Thus, the continuous converting process rather than a conceptual process alternative is becoming a necessity for a smelter facing limited converting capacity and/or lacking of fulfillment of the environmental regulation with its maximum converting capacity. The objective of this paper is to present the progress of the Codelco continuous converting process evaluated at pilot-scale level when converting solid mattes or white metal into blister copper. These tests allowed for gathering of relevant data to be considered for a new stage of evaluating the Codelco continuous converting at industrial-scale test. The pilot-scale tests were done in a Teniente Converter pilot scale unit at the Codelco Norte Smelter. The results of processing solid copper mattes (65-75% Cu) and producing low sulfur content blister copper with production of a constant S02 gas concentration, and the production of liquid slag with low copper solubility was achieved and is discussed in the present paper.

Jan 1, 2007

By Ross D. Lawrence

"IntroductionOne of the methods used when applying the Market Approach to the valuation of a mineral exploration property is known as the Joint Venture Terms Method. The method is particularly useful for the valuation of early-stage exploration properties. Unfortunately, valuators are sometimes imprecise in distinguishing between joint ventures and other types of transactions.At VALMIN '94, Bob Appleyard1 proposed that, if one ignores the time value of money and the probability that the expenditure commitment would be completed, the formula to calculate the value ($V) of a property owned by Party B at the time of the deal would be:$V =$Ex (100-1%)/1% (Formula I)Where $V is the value of the property2Where $E is the expenditure commitment by Party A, andWhere 1% is the percentage property interest to be earned by party A.At PACRIM '99, Mike Lawrence and Graham Dewar3 referred to this method and suggested that there was an ambiguity in the formula proposed by Appleyard in 1994. Mike Lawrence referred to this problem again at VALMIN '014•Lawrence & Dewar suggested that the formulashould be:$V100% =($Ell%) x 100 (Formula 2)Where $V 100% is the value of the entire property,Where $E is the expenditure commitment by Party B, andWhere 1% is the percentage property interest to be earned by Party B.Subsequently, there has been considerable discussion in the AuslMM Bulletin5. In my view, this discussion has touched on a number of useful points, but generally has overlooked one essential element needed for an understanding of the correct application of the N Terms method. That essential element is to understand that there is a material difference between (1) entering into a joint venture arrangement and (2) the purchase of an interest in a property."

Jan 1, 2003

By V. T. Panayotov, M. I. Panayotova

Wastewater from mining and mineral processing activities is often polluted by anion forming metals, such as molybdenum and chromium. Low cost materials, including zeolites, are studied for removing heavy metals from wastewater. It is widely accepted that natural zeolites are not effective in removing metals in anionic form. The paper presents study on use of metal modified natural clinoptilolite to remove Mo (VI) and Cr (VI) ions from model soft wastewater. Modification with Pb, Fe(III), Zn and Ba increases clinoptilolite uptake capacity with respect to Mo(VI) at low pH values of the water subjected to treatment, the efficiency decreasing in the order Pb > Fe(III) > Zn > Ba. Only lead-modified clinoptilolite shows high uptake of Mo(VI) in acidic, neutral and slightly alkaline conditions. Modification with Pb, Ba and Fe(III) increases zeolite uptake capacity with respect to Cr(VI) from neutral water. The effectiveness of Ba-modified zeolite decreases in slightly acidic water. Over 90 % uptake of initially available Cr(VI) is achieved by lead-modified clinoptilolite both under neutral and slightly acidic conditions. Increasing the initial pollutant concentrations increases the removed amount both of Cr(VI) and Mo(VI) for Pb-modified clinoptilolite. The findings could be a basis for using the natural clinoptilolite to remove in consecutive steps: firstly Pb(II) and/or Fe(III) ions and then loaded zeolite to be used for Mo (VI) and/or Cr(VI) removal. The kinetics of Mo(VI) uptake by CL-Ba, CL-Fe(III), CL-Pb, and CL-Zn is best described by the pseudo-first order kinetic equation. The kinetics of Cr(VI) removal by CL-Ba, CL-Fe (II), CL-Fe (III) and CL-Zn is best described by the pseudo-first order kinetic equation. Kinetics of Cr(VI) removal by CL-Pb obeys the equation for the first order irreversible reactions. Finding way to remove anions-pollutants from the mineral processing wastewater will render this industry more environmentally friendly and socially acceptable.

Jan 1, 2016

By C. V. Corless

1. Introductory Some members may recall that at the Annual Meeting two years ago I read a paper, 'The Future of the Mining Industry in Canada." Discussing this large subject it was possible only to outline the facts and inferences leading to ?the conclusion that Canada is a country endowed with enormous mineral wealth, of which the fringes are yet scarcely touched. In the present paper, I wish to examine in somewhat fuller detail the evidence, both direct and inferential, concerning the mineral wealth of the greatest physical and geological feature of Canada-the Precambrian Shield. Many, if not most, of these facts are already familiar to you. But, since they will form the basis of the reasoning employed, they will be recalled for explicit reference. First, let us review very briefly the position and extent of the Shield. The area of the entire Shield is given in textbooks as 2,000,000 square miles, of which perhaps 10 or 12 per cent. is exposed in the south-easterly part of Canada's Arctic islands. The remainder occupies roughly two-thirds of the North-west Territory; the north-east corner of Alberta; one-third of Saskatchewan ;two-thirds of Manitoba; three-fourths of Ontario; and nearly ninety-five per cent. of Quebec.

Jan 1, 1924

By K. Hashiba, Y. Z. Liang, K. Fukui, M. Koizumi

"Efficiency and penetration rate during percussive rock drilling significantly affect the speed of tunneling and excavation. Many researchers and engineers have continuously engaged in the advancement of rock drilling performance. Development and modification of the rock drills based on test data are timeconsuming and costly. Hence it is essential to make effective use of numerical simulation. However, most of the numerical models proposed in previous studies were too simple in comparison with the actual percussive rock drilling in which many factors are involved. The objective of our research project is to construct a new realistic numerical model of continuous percussive drilling, which is based on the previous Okubo-Nishimatsu’s model. In this study, the parts of the previous model involved in stress wave propagation and attenuation were modified. The two models were prepared for HD712 hydraulic rock drill mounted on crawler drills and HD210 hydraulic rock drill mounted on drilling jumbos. Stress wave propagation was computed with the discretized one-dimensional wave equation. The calculated results were compared to the stress waves measured on a rod during percussive drilling. In both models for HD712 and HD210, the measured stress waves can be reproduced with the one-dimensional model of the same acoustic impedance as the actual piston, shank rod and rod combined with the CI+spring model as a rod joint. The calculated results indicate that the spring constant in the model of a rod joint needs to be set appropriately depending on drilling conditions. INTRODUCTIONEfficiency and penetration rate during percussive rock drilling significantly affect the speed of tunneling and excavation. Many researchers and engineers have continuously engaged in the advancement of rock drilling performance. Components related to the percussive drilling are a drill body, a piston, a shank rod, rods, rod joints, a bit and rock. The piston in the drill body is reciprocated by hydraulic pressure and collides with the shank rod a few thousand times per minute. Stress waves generated by the collision propagate and attenuate in the rods and rod joints, and then reach the bit. The bit penetrates and crushes rock. During percussive drilling, the components mutually affect each other and self-induced oscillation occurs. The number of blows and the rate of penetration are determined by the practical drilling conditions such as hydraulic pressure, thrust force, number of rods and mechanical properties of rock. Development and modification of the rock drills based on test data are time-consuming and costly. Hence it is essential to make effective use of numerical simulation. However, most of the numerical models proposed in previous studies were too simple in comparison with the actual percussive rock drilling in which many factors are involved."

Jan 1, 2015

By P. Karimi, A. Amini, H. Abdollahi, A. Mirzaeian

Due to detrimental effects of cyanidation process on the environment in gold industry, application of cyanide alternatives such as thiourea are being highly considered in recent projects. In this study, the extraction of gold from poly metal ore, using thiourea was precisely investigated. The representative sample contained 2.5 ppm Au and 160 ppm Ag. The sample was categorized as oxide gold ore, because the main part of its pyrite was changed to iron oxide and hydroxide such as goethite and lepidocrosite. According to mineralogy, the main gangue mineral was quartz. It shows that gold grains are free and interlocked with quartz matrix. Also, the presence of a high amount of silver in free and sulfide forms and also the low content of other sulfide minerals such as base metal sulfides is a remarkable point of these studies. In the gold extraction process with thiourea, there are several parameters that affect the rate of gold dissolution such as concentrations of thiourea as a gold lixiviant and ferric sulfate as an oxidant, pH and size fraction of feed and leaching time. The influence of these parameters on the gold dissolution rate were investigated and optimized. The results showed that the concentration of thiourea is the most influential parameter which could increase the gold recovery to 71% (at 10 g/kg sample). The optimal amount of ferric sulfate was determined as 6 g/kg sample. Also, the optimal levels of size fraction of feed and pH of solution were 88% under 75 micron and 2 as acidity; respectively. Leaching time was 6 hrs. In addition, this sample was leached with cyanide and the optimized values of size fraction of d88=75 microns, pH=10.45, 2500 ppm of sodium cyanide with time leaching of 24 hours were concluded for maximum recovery of gold in solution. Finally, the results of cyanidation tests were compared to the thiourea dissolution after optimizing all affected parameters in cyanidation process.

Jan 1, 2016

By M. Tadie, J. Wiese, K. Corin

The use of potential control in the flotation of ores has been applied in a variety of operations and presents an opportunity for improvement of selectivity and recovery of valuable minerals. Although it is possible to vary the redox potential (Eh) using chemical additives such as sodium hypochlorite or hydrogen peroxide this is more commonly done by varying the pH and dissolved oxygen (DO) concentration. The present study involves an investigation into the effect of varying dissolved oxygen concentration, ionic strength (IS) and pH on the flotation response with the aim of application to a South African lead-zinc ore. In all cases the Eh is measured as a function of the different DO, IS and pH values. The main objective was to achieve selective flotation of galena from sphalerite. The first part of the work was micro-flotation tests conducted on single minerals with galena used as the basis for effect of the factors studied on redox potential and ultimately recovery. The DO was varied by alternating between the use of air and nitrogen as the gas source to the micro-flotation cell. PH was varied between pH 9.2 and pH 11.8 using sodium hydroxide. In the first part of this study a factorial design approach was used to determine the interactive effects of the variables tested, viz. DO, ionic strength and pH, on the Eh and on the recovery. Redox potential was measured using a combination electrode made up of platinum wire and Ag/AgCl reference combination. Recoveries indicated that pH had the most significant effect on recovery and Eh. The influence of redox potential on recovery was found to be of relevance to the condition of high dissolved oxygen concentration and less so at low dissolved oxygen concentrations. It was also noted that that the combined interaction between ionic strength and dissolved oxygen concentration had a positive effect on recoveries, however this was not so with Eh. The chemistry of the ions in solution was observed to play a dominant role on the recovery due to changes in solubility arising to pH modification. The longer term objective of this work is to determine the optimal Eh conditions for the separation of galena from sphalerite.

Jan 1, 2016

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