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By Takashi Furuyama, Sukeyuki Mori, Abel Bissombolo

"In flotation practice, a good recovery of minerals largely depends on the degree to which the valuable minerals have been liberated from the associated gangue during the grinding process. Therefore, a regular measurement of the degree of liberation can provide data for the assessment of the quality of separation and predicts the effect of changes in the grinding-classifying circuit on flotation process. Generally, the standard procedure for measuring the degree of liberation requires the preparation of polished sections - a time consuming operation that also has the disadvantage of providing an overestimated number of free particles because of the stereological nature of produced samples.The present work is an alternative approach to avoid these miscalculations and establish a system of control for fluorite flotation plants. The system deals no only with the state of liberation but also the dynamic behavior of individuals particles and mineral components within the grinding-classifying and flotation circuits. It involves methods such as sieving, x-ray diffraction analysis, study of polished sections and microscopic counting of preliminarily sieved minerals particles from a fluorite processing plant, randomly dispersed on a glass slide, but not embedded in a resin mounting medium. If a complete information on the textural properties of minerals in the ore (including its mineral components distribution) can be obtained through x-ray diffraction analysis and study of polished sections, the microscopic counting is used to determinate with enough accuracy the mineral liberation, estimate the grade of fluorite ore and products, determinate the deportment and approximate recovery of individuals particles and mineral components within the investigated circuit. For a count of 100-1000 particles in each n-size range, the counting method was found to be a particularly reliable and less time consuming operation that could substitute the chemical analysis of fluorite ore for an estimate of the grade:"

Jan 1, 2003

By M. Barsky, A. Govorov, E. Barsky

A study was conducted to determine the structure and lifting capacity of a two-phase stream in a vertical pipe at different distances from the point of introduction of the material into the instrument. Stream velocity was set at 2.8, 4.0, 4.8, 5.6 and 6.25 m/sec to ensure separation regimes. It was found that the llifting capacity of the two-phase stream exceeded that of pure air by a factor of three or more, and that in a turbulent regime the velocity curve displayed marked deformation, becoming more rounded and tending towards a parabola. The following formula was obtained for entrainment of a given size fraction under turbulent, laminar and transitional particle flow regimes:

Jan 1, 2003

By E. Barsky

"The aim of separation is to obtain two products that are as distinct as possible from each other. It is currently believed that the most objective criteria for the quality of a separation are the Hancock criterion and the entropy criterion.1. Hancock criterion:- for yield of fine product"

Jan 1, 2003

By Tamara F. Kondrateva, Evgenia E. Savari, Galina V. Sedelnikova, Rauf Y. Aslanukov, RAS (INMI), Grigori I. Karavaiko

"The investigation is dedicated to study of biohydrometallurgical processing of refractory gold-arsenic concentrate with the large content of pyrrhotite. Sulfide concentrate of chemical constituents: 75g/t Au, 4,7g/t Ag, 6,3% As, 29,3% S, 2,3% Sb, 0,5% ? (organic) and of mineral composition, %: 11,8 arsenopyrite, 39 pyrrhotite, 12 pyrite, 2,9 antimonite and the rest – aluminosilicates, carbonates and quartz, was studied. The recovery of gold from concentrate by cyanidation is 51,2%. The rest of gold is embedded as finegraded segregation in sulfides.Sulfide oxidation process study is described. Bacterial oxidation was executed on a pilot laboratory unit using combined autotrophic bacterium: A. thiooxidans , A. ferrooxidans, Leptospirillum ferrooxidans and sulfobacillus thermosulfidooxidation, pH=1,5-2,2, t=28-32?C, oxidation time 120 hours. Pyrrhotite is the least stable sulfide mineral with electrode potential 0,45V versus arsenopyrite (0,55 V) and pyrite (0,55-0,6 V) and is oxidated primarily. Pyrrhotite oxidation is followed by large amount of elemental sulphur, which has a bad influence on cyanidation.It’s established that the rate of arsenopyrite (for the first 48 hours) from concentrate containing 39% pyrrhotite is 2-3 times as less as the rate of arsenopyrite bio-oxidation from concentrate without pyrrhotite. The arsenopyrite bio-oxidation is accelerated only after the elemental sulfur was oxidized by bacterium A. thiooxidans and elemental sulfur percentage was reduced from 6,8 to 3,9%. The bacterium concentration is increased from 2,5x107 to 2,5x109 cells/ml. Almost full oxidation of arsenopyrite (98%) and pyrrhotite (98- 99%) is finished in 120 hours. We have studied two pretreatment methods for elimination sulfur content influence on cyanidation: aeration in lime and electrochemical treatment. Such an operation enables to have supplemental oxidation of elemental sulfur and other oxygen and cyanide absorbants before cyanidation. After treatment the content of elemental sulfur was decreased from 3,9 to 2,2%, gold recovery from 90 to 96% and cyanide consumption from 16,2 to 7,2 kg/t decreases. The content of toxical rhodonite-ions in liquid phase of pulp and disinfection reagents consumption were decreased as result of elemental sulfur content in bio-oxidated product reduction."

Jan 1, 2003

By József Faitli, Barnabás Csoke, Károly Solymár, Zoltán Hatvani, Dimitri Papanastassiou

In most cases, the sizing of dry or wet mills for ore processing is primarily based on the determination of the Bond grindability index, using the Bond-Kjos-Rowland relations. In several cases, grinding takes place under conditions different from these and the grinding conditions have a great influence on the postgrinding process. This is particularly true for the grinding of bauxites where grinding takes place in alkali, often in higher temperature in alkali Liquor. So it is necessary to develop a testing method providing a reliable grindability index even under these special circumstances and allowing a more precise mill sizing. Therefore we surrounded the grinding crucible of the Hardgrove mill with a crucible furnace to heat it. The new heated mill is suitable to determine the grindability index under temperature-controlled circumstances, in liquids (water and alkali) with different temperatures. The required heating power is 2000 W. In the implemented equipment we installed four 230V/500W electric heating wires made from heat-resistant alloyed material and surrounded by ceramic insulators. The temperature and temperature-gradient are measured by four PT100 platinum thermal resistors. The data acquisition and control program written in the C language in the Lab Windows CVI program environment measures the voltage proportional to the temperature. Determining the grindability indices of hungarian and greek bauxites experimentally, first dry grinding tests were carried out under standard conditions. During wet and alkaline grinding, to 50 g of dry bauxite 85.5 g of industrial alkali with a concentration of about 200 g/l was added. As grinding aid 2 g of CaO (4 % of dry bauxite) was dosed. From the data it can be concluded: - The tested bauxites show a similar behaviour against temperature change. However, the extent of grindability change is different for different bauxites. - Soft Hungarian boehmitic bauxite can be ground in a high-temperature alkaline medium better than hard Greek one. The increase of grindability according to the high-temperature Hardgrove indices: (kHT = Dry o HT,alkaline H /H ): for hard Greek and soft Hungarian boehmitic bauxites: kHT = 1.7 and 2.4 respectively; according to estimated Bond indices (kB,HT =Wi,dry/Wi,HT, alkaline ): kB,HT = 1.6 and 2.1. - The increase of grindability is the most important factor the reaction of kaolinite with caustic liquor and lime and the loosing of the textural structure at 80 ºC and especially at 100 ºC.

Jan 1, 2003

"The Merensky Reef is a platinum group minerals (PGM) bearing reef in the Bushveld Igneous Complex in South Africa. The reef has been treated by bulk PGM and sulphide flotation with the aim of maximisingthe valuable minerals recovery and gangue minerals rejection.Synthetic water with a calcium concentration of 80 ppm and 500 ppm was prepared and the flotation results obtained were compared to a simple electrolyte in order to determine the effect water quality has on pentlandite and pyroxene surface alteration and, ultimately, floatability. During the study, the possible effect of interactions between the minerals investigated and Ca2+ ions in the presence of sodium isobutyl xanthate was studied at pH 6 and pH 9 by means of zeta potential determinations, microflotation tests and ToF-SIMS analysis.The results obtained on 1:1 pentlandite-pyroxene mixtures showed that the quality of process water plays an important role in flotation. The flotation recoveries of pentlandite and pyroxene were lower in synthetic process water compared to those obtained in a simple electrolyte solution."

Jan 1, 2003

By Kauko T. Ingerttilä, Jouko O. Kallioinen, Jaakko O. Leppinen, Alexander V. Lashkul, Vladimir E. Nenno

"Separation in Froth (SIF) is a process for the separation of mineral particles during their descent downwards through a moving froth layer, generated on the surface of water or some other liquid media by means of a bubble generator and frother. Due to the special operation principles of SIF it is possible to separate mineral particles that are about 10 times coarser than the optimal particle size for conventional flotation. In this paper the performance of the SIF technique is presented in the separation of apatite, calcite and silicate minerals from various industrial sources, based on tests with laboratory and pilot plant-scale SIF machines. Basic laboratory test results of the flotation of pure diamonds are also presented.It was shown that calcite, apatite and diamonds with particle size up to about 3 mm can be successfully floated with SIF at high recovery and grade, provided that the degree of liberation is sufficiently high. Coarse calcite (+0.25-2.8 mm) was concentrated with reverse SIF in one flotation step at 87% recovery with better than 99% grade. Apatite particles coarser than 0.2 mm are not well floated in the conventional flotation circuit leading to high P2O5 content in the coarse size fractions of flotation tailings. On the contrary, SIF is capable of recovering such coarse particles at high recovery. However, P2O5 content of the SIF tailings starts to increase at about 0.7 mm due to insufficient liberation of apatite. At higher particle size the lack of hydrophobicity of apatite particles is also likely to lower the recovery.The pilot plant testwork showed that SIF can be successfully used at operating plants not only for preliminary upgrading of the feed of conventional flotation, but also for producing final grade calcite concentrate (>99.5%) from the screen overflow or from the cyclone underflow in a particle size range up to 1 mm. It was particularly promising that the separation took place in one SIF flotation step, instead of several stages of the conventional flotation circuit, with over 90% calcite recovery. The specific capacity determined with the 1 m2 pilot plant unit was approximately 30 t/m2h. Simultaneously the consumption of chemicals was significantly lower than for conventional flotation."

Jan 1, 2003

By Rob D. Morrision, Paul W. Cleary

"The best accepted method for design of autogenous and semi-autogenous mills is to carry out pilot scale test work using a 1.8 m diameter by 0.6 m long pilot scale test mill. The load in such a mill typically contains 250,000-450,000 particles larger than 6 mm, allowing correct representation of more than 90% of the charge. This scale of DEM model is now within the practical range of standard workstations running an efficient DEM code.This paper describes various ways of extracting collision data from the DEM model and translating it into breakage and wear estimates. Account is taken of the different breakage mechanisms (impact and abrasion) and of the specific impact histories of the particles in order to assess the breakage rates for various size fractions in the mills. These impact histories have the potential to be directly related to breakage as they most resemble the single particle breakage tests which are used by the JKMRC to calibrate more traditional population balance models for variations in ore behaviour. However, the specific impact histories also show a background of many low energy collision events within the mill. This Background may constitute what is usually regarded as “abrasion” breakage. As might be expected, high impact events are concentrated in the toe of the charge and near to the mill shell where the forces associated with the load bearing on each particle is more concentrated."

Jan 1, 2003

By Susanna G. de Jager, Francis W. Petersen

"To enable the prediction of reagents suitable for fine coal flotation, it is necessary to develop a methodology applicable to different South African coal types. Statistical confirmation of the applicability of this methodology is important to avoid recommendation of reagents on a trial and error basis.The study included 5 coal samples from different collieries and included Highveld seam 3 and 4 coal (as one sample), Waterberg coal (zone 10 -11), Highveld seam 5 upper coal and Witbank seam 2 and seam 4 coal. Seam 3 and 4 (mixture) coal, Waterberg and the seam 5 upper coal were all found to be vitrinite rich coals. The coal characterisation study included petrographic analysis, proximate analysis, float-sink analysis, oxygen-containing functional groups, surface extraction, flotation release analysis and contact angle measurements. Flotation tests were used to validate expectations from the characterisation of the coal samples.RESULTSThe flotation data indicated that all of the coal samples were amendable to froth flotation. The best results were obtained with the Witbank seam 2 coal and the poorest flotation with Syferfontein seam 5 coal. The flotation tests showed that the best reagents to float all of the coal samples studied were iso-decanol and dodecene. These reagents produced flotation products that were near to the release curve, which are the optimum flotation results (obtained when using iso-paraffin as collector). Dodecene resulted in low ash products and iso-decanol in high yield products."

Jan 1, 2003

By F Battaglia-Brunet, D. H. Morin, Foucher S. ’

In the mineral-processing field, bioleaching of metal sulphide concentrates is currently operated in very large mechanically agitated tanks. Such bioreactors have considerable requirements in terms of power consumption for mixing, aeration and heat transfer. The use of slurry bubble column, where the particles are suspended by gas motion as well as by liquid upward flow, could be an alternative to achieve bioleaching in more economical conditions. In order to compare these two techniques, a unit of stirred reactors in cascade and a bubble column were comparatively operated at laboratory scale in the bioleaching of a pyrite concentrate. For both pieces of equipment, experiments were performed not only in batch mode but also in continuous conditions.

Jan 1, 2003

By Leon Lorenzen, Charlene Gokhale

"In excess of 24 x 106 tons (Eskom, 1997) of coal-derived fly ash is produced annually in South Africa for the production of electric power. A large quantity of this ash is disposed of as a solid waste in landfills, thus posing a serious environmental problem. Due to the shortage of landfill sites, new ways of utilising fly ash are needed. Recently several authors have shown that various combustion fly ashes can be converted into zeolites to obtain industrial products with applicability in environmental management. Geopolymerisation has emerged during the last few years as a possible solution to some waste stabilisation and solidification problems. henolic compounds have been shown to be toxic to soil microorganisms at the parts-per-million level. Indeed several of the organic compounds classified by the U.S. Environmental Protection Agency as priority pollutants, are phenols. Immobilisation of phenols by adsorption on zeolites and encapsulation in a geopolymer appears to be a promising solution to this problem.This paper reports a technique for the production of a low-silica sodium zeolitic material from fly ash (zeolite NaP1), and its application for the stabilisation of phenols by adsorption and subsequent encapsulation in a geopolymer matrix. A commercial zeolite, clinoptilolite was also utilised as an adsorbent. Due to their uniform pore sizes and large surface areas, zeolitic materials are suitable for ion exchange and adsorption of certain organic substances. Adsorption data show that the commercial zeolite, clinoptilolite was an effective adsorbent for organics. Adsorption data showed that between 51.2 ppm and 74.3 ppm of chlorophenol or between 15.4 ppm and 32.5 ppm of phenol could be adsorbed. Physical encapsulation of the coated zeolite loaded with organic within a geopolymeric matrix increased the compressive strength of the matrix from 28.80 kN to 40.79 kN. Leaching data for the various geopolymer matrices with encapsulated and loaded zeolites show no organics being leached from the system at a detection level of 2ppm. According to the SABS these would have been acceptable organic concentrations within a waste water stream."

Jan 1, 2003

By Elzbieta Mielczarski, Jerzy Mielczarski, Jan Drzymala, Yann Duval

"The monoalkyl ethers of polyethylene glycols are universal flotation reagents because they can be used as collectors, frothers, surfactants, and depressants. Their collecting power was demonstrated for different minerals including coal and quartz.It was confirmed in this work that monoalkyl ethers of polyethylene glycols could be used as collector in flotation of quartz in a monobubble Hallimond cell. Since feldspar does not float in the same cell, it was also shown that selective separation of quartz and feldspar in the Hallimond tube is possible. However, a trail to use the monoalkyl ethers of polyethylene glycols compounds for separation of quartz and feldspar by flotation of mixture of these minerals in a Mechanobr laboratory flotation machine was futile, indicating that these reagents required special environment for flotation.Most probable parameter responsible for a decrease in quartz flotation in the flotation machine is the hydrodynamics of process, and different adsorption/desorption conditions. To prove this, another series of experiments was carried out to separate quartz and feldspar, in which a laboratory flotation column was utilized. The performance of the flotation column was in between that of in the Hallimond tube and flotation machine. These experiments confirmed that the hydrodynamics of flotation plays a vital role in flotation of quartz with monoalkyl ethers of polyethylene glycol compounds."

Jan 1, 2003

By E. Lee

With the growing environmental concern, as well as the increasing concern for sustainability of natural resources, the need of improving the performance and efficiency of today?s crushers is be-coming increasingly important. However, the development of existing crushers requires an extended basic knowledge about the crushing process itself. The aim of the present study is therefore to find the theoretically optimal way of crushing compressively under given circumstances. In the present paper, optimizations have been performed with the purposes of maximizing product yield and minimizing energy consumption. Performed on an ideal crushing stage free from physical limitations, the optimization results have been obtained in terms of number of compressions and their corresponding compression ratios. Complementing earlier results on interparticle breakage (Hulthén et al., 2006), presented here are thus the results from corresponding optimizations with single particle breakage and interparticle breakage. It is concluded that modern crushers are not working optimally in any of the studied aspects for gneiss. In fact, optimizations indicate that a lowering of the compression ratio, as well as a shortening of the crushing sequence, are theoretically favourable. The outcome of this study is therefore highly promising as to giving new ideas and suggestions of improvements in existing crushers, and can even result in redesign of compression crushers.

Jan 1, 2014

By P. N. Mohan Das, K. Harikrishna Bhat

"The major ilmenite reserves are located in India at Chavara (CH), Manavalakurichi ( MK) and Chatrapur, Orissa (OR). India stands first in terms of ilmenite reserves, which are estimated to be 278 million tonnes out of which, 142 million tonnes are processable. Mineralo-chemical analysis showed that Chavara ilmenite is the most weathered one with about 60% TiO2 while Chatrapur is the least weathered with about 50% TiO2. XRD and SEM studies of different magnetic fractions of these three mineral deposits established the co-existence of ilmenite with pseudorutile, rutile and haematite phases in substantially varying amounts. It is observed that the tropical weathering rather than the source rock difference has apparently played an important role in imparting major compositional and structural dissimilarities among the ilmenites in different places. Further, the chemical analysis, XRD and SEM characterisation of differently weathered samples of MK ilmenite separated by the magnetic fractionation showed that the degree of alteration was invariably associated with the decrease in magnetism, increase in the rutile phase and the change in Fe2+/Fe3+ ratio of ilmenite grains. Magnetically separated fractions when subjected to metallisation with carbonaceous reductant such as coke showed that the degree of reduction increases with the degree of alteration and with the decrease in the Fe2+/Fe3+ ratio.In the processing of ilmenite through the Becher process, aeration rusting of pre - reduced ilmenite is found to be the rate-limiting step thus, affecting the productivity and economy of the process. Investigations have proved that the addition of some organic compounds such as glyoxal, sucrose etc., to the system accelerates the reaction to such an extent that the rusting time has been reduced to less than half. The formation of acids by the these organic compounds during the rusting reaction was proved responsible for maintaining the pH of the solution in the range 3-4 at which iron hydroxide do not precipitate and block the pores in the reacting surface of the grain."

Jan 1, 2003

By Carin Laubscher, Francis W. Petersen, Jaap P. Smit

"Waste streams, such as acid mine drainage, are often characterised by low pH values and high concentrations of heavy metals, dissolved solids, calcium and sulphates. Although lime remediation effectively removes most of the heavy metals as hydroxides, it is less effective at lowering levels of sulphates. Various methods of removing sulphates from effluents exist, such as precipitation with lime, precipitation with barium salts, co-precipitation with calcium carbonate, reverse osmosis, and ion exchange. Mintek developed a chemical precipitation (SAVMIN) process to treat acid mine drainage, which entails the addition of lime to precipitate the metal hydroxides, and the subsequent formation (precipitation) of calcium sulphoaluminate or ettringite. The key to the viability of the new technology lies in the correct use, regeneration and recycling of Al(OH)3 used to precipitate the ettringite. The water produced by this process is suitable for disposal to watercourses or for agricultural, domestic or industrial consumption. No brines are produced as the salts are converted to solid hydroxides, gypsum and calcium carbonate.The SAVMIN process has been tested successfully during several laboratory scale operations, and during two pilot plant operations at Stilfontein Goldmine for Anglogold and Navigation Plant, Witbank for Anglocoal. During the pilot plant campaign at Navigation Plant, metal and mineral precipitation was achieved with lime addition. The sulphate concentration in the water was reduced from 2136 mg/L to an average value of 102 mg/L and the calcium concentration was reduced from 727 mg/L to an average value of 70mg/L.The SAVMIN process generates a number of different waste streams including metal hydroxide sludge from neutralisation, gypsum sludge from the gypsum crystallisation steps, and calcite sludge from carbonation. The metal hydroxide sludge is composed of Mg, Ca, Mn and Fe hydroxide, and could be disposed of on a slimes dam. Gypsum sludge was greater than 99% CaSO4.2H2O. This gypsum could be used for dump or road capping, underground backfilling, production of wallboard and cement. The calcite sludge is pure CaCO3, which is recycled back to the neutralisation stage."

Jan 1, 2003

Certainly, one of the core processes for the recovery of fine magnetic susceptible iron ore particles, mainly hematite iron ores, is the wet high intensity magnetic separation or WHIMS. This paper outlines a variety of recent developments and innovative process designs in the JONES® type WHIMS. It highlights the latest examples of flow sheets in terms of the diversity of combined rougher, scavenger, cleaner stages and adds to this the new more advanced JONES® type WHIMS equipment technologies like the HIGH FLOW ? HF, the QUATTRO ? Q and the SPLITT OPERATION ? SP. As a result of the increase of the capacity and magnetic intensity, the specific production cost could be decreased. The high worldwide acceptance for this continuous development testifies for the success and state of the art technology.

Sep 1, 2012

By Dave Deglon

"The Western Cape Mineral Processing Facility (WCMPF) is a collaborative educational initiative between the Departments of Chemical Engineering of the University of Cape Town, the University of Stellenbosch and the Cape Technikon. The primary objective of the WCMPF is to facilitate the education, development and graduation of suitably qualified engineering graduates and diplomates for the mining industry. The WCMPF consists of academics and Technical Officers in the Departments of Chemical Engineering of the three tertiary institutions. The Technical Officers are usually metallurgists, with several years of industrial experience. The main objective of the Technical Officers is to improve the practical education of mineral processing students. In addition, the Technical Officers are responsible for organising an annual mineral processing student field trip for students from all three tertiary educational institutions. In recent years the WCMPF has embarked on a number of additional initiatives aimed at improving the quality of mineral processing education. These include the development of several new pilot plant practicals, an initiative in pyrometallurgy, the introduction of novel ‘end to end’ or ‘integrated’ practicals and the use of mineral processing simulation packages to complement the practical training.The WCMPF has been functioning for well over a decade and, by virtue of this, might be considered a successful collaborative educational initiative. The WCMPF has played a key role in the education of over five hundred mineral processing graduates and diplomates. During this time period, the WCMPF has gained a body of internal knowledge which might be of benefit to other educational institutions, viz."

Jan 1, 2003

By Vladimir I. Ryaboy, Konstantin M. Asonchik

"At flotation of sulfide-barite ores of one of deposits sulfide and barite concentrates are obtained. In sulfide cycle potassium xantogenate as a collector in consumption of 200 g/ton, methylisobutylcarbinol (MIBC) as a foaming agent in consumption of 30 g/ton and also liquid glass are used. In barite cycle tall oil as fatty acid collector in consumption up to 400 g/ton is used.Sulfide concentrate represents mainly gold- and silver-containing pyrite. The contents of gold makes not less than 10 g per ton, silver - not less than 278 g/t. Barite concentrate contains up to 86% of barite.Factory is working in water recirculation conditions. Owing to that in barite cycle fatty acid collector is used, technological water from tailing repository contains fatty acids soap up to 25 mg/l. Before submission into sulfide cycle this water is conditioned with active carbon to delete the main part of fatty acid collector. The active carbon consumption makes 0,4-0,5 kg per 1m3 of water or 1,5-2 kg per ton of ore. The above mentioned consumption of active carbon improves reducing of contents of fatty acid collector from the initial concentration of 25-30 mg/l to 4 mg/l. At concentration 4 mg/l fatty acid collector does not render negative influence on flotation index in sulfide cycle. At the absence of active carbon pollution of sulfide concentrate and its irrevocable lost are observed."

Jan 1, 2003

By Osvaldo A. Bascur, J. Pat Kennedy

"The profitability of mining and metallurgical operations continues to lag behind that of other industries despite the technical advances that have occurred in recent years. A primary reason for poor performing in this economic sector is the lack of integration of mining and metallurgical information. The mine cut-off grade can be optimized if mining and metallurgical engineers have the data to optimize milling for the type of ore in hand.Integration of mine transactions, stockpile inventories, process flows and assays is the key to determining the economics for each blast strategy in a mining site. Real-time information from manufacturing assets greatly affects the profitability and flexibility of a company, but gross errors from faulty sensors, inaccurate instrument calibration, or incorrect process models may corrupt actionable information. New software tools can model the process, sift through available data to identify and eliminate gross errors, and use statistical data reconciliation to create materially balanced and consistent readings. The reconciled data is unified for use by both monitoring and decision making processes.Creating a real-time information environment where upgrade and change are allowed is becoming an accepted methodology to accelerate and simplify the integration of applications such as production monitoring, equipment performance management and yield and inventory management."

Jan 1, 2003

By M. T. Spyridopolous, S. J. Neethling

"There has been a significant research interest in the stability of single thin films, including prediction of their failure based on disjoining pressure and film thickness experiments and DLVO theory. It is, however, notoriously difficult to correlate information on the failure of a single thin film with measurements of foam stability. This is particularly true for the prediction of dynamic foam stability indicators, such as equilibrium froth height and surface bubble size.An alternative experimental approach to studying single thin film failure for predicting foam stability is to measure directly the coalescence probability between two approaching bubbles in a surfactant solution. These experiments can be performed under different chemical and physical conditions by using a micromanipulator that allows variation of bubble size, surfactant concentration, approach velocity and stationary position. The interface radius of curvature, the time to coalescence and the film area between the bubbles can be measured directly using image analysis.In a foam, the force exerted on the thin film separating two bubbles depends on the local radius of curvature of the Plateau borders and vertices, which depends in turn on the local liquid content. Results from different bubble sizes in the micromanipulator therefore translate into regions of different liquid content in the foam. Small bubbles, having a high radius of curvature correspond to the low-liquid content (Polyhederschaum) region higher in the foam, and large bubbles to the wetter (Kugelschaum) region closer to the liquid-foam interface. Experiments with different holding distances between the bubbles correspond to differences in bubble size in the foam, as the size of the film between the bubbles varies."

Jan 1, 2003