Search Documents

By Shek N. Lau, Nicola Samman

"Enclosed gear cases on board heavy mining equipment have traditionally been lubricated with regular heavy duty gear oils. However, equipment manufacturers, have recommended the use of an ISO-1000 gear oil for this application to ensure adequate lubricant film strength, especially at the higher end of the working temperature range. The majority of these ISO-1000 gear oils are based either on residual/asphaltic oil or synthetics, primarily higher viscosity polyalphaolefins. Although the performance of these lubricants has been satisfactory, they suffered other shortcomings that equipment users have lived with over the years.The major requirement at the user’s mine was to provide lubrication for the shovel Hoist gear case. Within such a gear case design, the gears and the roller bearings, that have different lubrication requirements, are lubricated with the same lubricant. Several lubricants were used, light gear oils as well as the recommended ISO-1000 heavy gear oils. On the one hand, the lighter oils performed adequately for the lubrication of the bearings that formed part of the enclosed gear system. These lighter oils did not perform as well for the lubrication of the gears due to their lower viscosities, resulting in shorter gear servicelives.On the other hand, the ISO-1000 gear oils performed well for the lubrication of the gears, but were too viscous to creep into the bearing elements to lubricate them adequately, especially during the cold northern Canadian winters. This resulted in catastrophic bearing failures and secondary damages to the gears.The challenge, then, was to formulate a lubricant which met the 1000 cSt at 40°C viscosity requirement as stipulated by the equipment manufacturer, while satisfactorily lubricating the bearings at the full working temperature range. This was achieved by the development of a semi-fluid grease lubricant, which has proven in field trials to give adequate performance in this application for the lubrication of both the bearings and gears down to -40°C.This product met the equipment manufacturer’s performance criteria and resolved, to a large extent, leakage of the lubricant through seals experienced with the use of conventional and synthetic gear oils.Although the main performance criteria of the fluid was its capability to lubricate the “Hoist” gear case, it was also used during the field trial in other gear cases on board the shovel to test its full capabilities.This unusual alternative lubricant was field tested and evaluated for more than two years. Based on this assessment, the product was reformulated to improve its fluidity, slumpability and the settling of debris/wear metals to the bottom of the gear cases. This reformulated softer grade, a semi-fluid grease, has been performing satisfactorily for more than eight months and is still undergoing longer term assessment."

Jan 1, 1996

By J Ortiz

In almost all copper mining companies, mine planning is done considering different time frames, leading to long-term (life-of-mine) (LOM), medium-term (first three years) and short-term (first year, monthly, weekly, and up to daily plans). Shorter term plans are usually associated with more abundant information, hence models with lower uncertainty. However, they capture more of the variability found on the geological attributes. In long-term models, usually estimation methods tend to hide this variability, providing smoothed interpretations.Medium and long-term plans consider average values for the parameters and optimisation techniques are applied aimed at maximising the economic profit. Short-term plans, on the other hand, are made to comply with the medium-term promises, maximising the use of the available resources (equipment and processing capacities) and dealing with the variability not characterised in the previous planning stages. This generates an important gap between the short-term and the medium and long-term plans. A case study was made using an important oxide copper mine, where the variability found in the short-term plan has a large impact in the productive process, thus reducing the daily ore grade variability is an important goal. In this paper, this planning issue is addressed by creating medium-term mine plans using mixed integer programming which are compared using the output of a simulation of the daily extraction that is aimed at satisfying the daily constraints of the processing plant, the availability of mining equipment and the variability of ore grade. The result shows the expected gap between these mine planning processes, which suggests correcting some of the parameters used in future medium and long-term plans.

Sep 26, 2011

By J Zhou, T D. McGrath, K P. Galvin, C P. Lowes, J J. Eksteen

Pre-concentration of low grade ores can improve the economic and environmental sustainability of an operation significantly, with opportunities for implementation ranging from run-of-mine to mill discharge depending on ore specific characteristics. For a gravity separation, where the performance is fundamentally constrained by mineral liberation, these feeds often represent a very difficult separation given the dominance of the relatively coarse gangue and fine liberation sizes. Thus, building knowledge of the feed through characterisation of the density distribution is critical to assessing amenability before progressing towards lab/pilot-scale test work and full-scale operation. The traditional approach to determining the density distribution typically involved sink/float testing, however, recent developments in hydrodynamic fractionation using inclined channels now offers a more cost-effective alternative with minimal health and environmental risk. A non-hazardous dense liquid, namely an aqueous solution of lithium heteropolytungstates (LST), is supplied as fluidisation to a REFLUXTM Classifier, consisting of a vertical section below a system of inclined channels, operating in semi-batch configuration. Fractionation is achieved by increasing the flow rate incrementally and collecting the particles to form a series of flow fractions. The purpose of this paper is to present this new method in the form of a case study, aimed at assessing the amenability of a low grade gold-bearing sulfide ore to pre-concentration. The robustness in the method is demonstrated through comparison with sink/float data, examining the density distribution and the liberation-limited product grade and recovery achievable. These data are then used as a benchmark to assess water-based continuous gravity separations conducted on the feed using a laboratory-scale REFLUXTM Classifier. This data set is used as the basis for process modelling and empirical validation for the recently established partition surface of the separator.

Nov 10, 2020

By P. Koh

A novel approach incorporating computational fluid dynamics (CFD) and flotation modelling has been used for investigating flotation cell designs. CFD modelling has increasingly been employed to enhance understanding of the cell hydrodynamics in mineral and coal flotation. Opportunities for improving the flotation cell performance can be identify by modelling. The CFD-flotation model from CSIRO incorporates cell hydrodynamics that affect particle-bubble interactions. Information from the model includes velocities, turbulent dissipation rates, gas hold-up, particle-bubble attachment and detachment rates. The attachment and detachment rates have been found to be effective measures of cell performance for cell design.

Jan 1, 2011

By Arash Khosravifar, Amalia Giannakou

"Nonlinear foundation springs for bridge caisson foundations show significant coupling between the shear force and bending moment. Implementing foundation stiffness matrix with coupling effects (off-diagonal components) into the global bridge model presents numerical challenges. A simplified approach is developed to model foundation springs including coupling effects using a simple methodology. This simplified model include one translational spring and one rotational spring combined with a rigid link in 2D space. Results show that nonlinear springs (translational, rotational and coupling) can be reasonably captured using this simplified procedure.INTRODUCTIONThe Izmit Bay Bridge is a 3-km long suspension bridge that crosses Izmit Bay in Turkey and is being constructed in a highly seismic region. Figure 1 shows the project location. The South Approach Viaduct (SAV), located along the western margin of Hersek peninsula, is within 5 km from the North Anatolian Fault and within a zone of secondary deformation around the primary trace of the North Anatolian Fault. The proposed SAV consists of 11 Piers and an abutment at the south end of the structure."

Jan 1, 2017

By R. Mensah-Biney

The NC State University Minerals Research Laboratory (MRL) and Waste Reduction Partners (WRP) of the Land of Sky Regional Council joined efforts in 2000 to initiate a technically sound and practical program for the management of high-volume coal combustion by-products (CCBs) in North Carolina. The accumulation of CCBs from coal burning boilers throughout the state of North Carolina posed a substantial storage problem, and the area was overripe for an effective management program, which would be environmentally sustainable. In particular, the public utility generators had filled storage ponds on their properties, and the storage overload had grown to critical proportions. Much the same situation existed for paper mill biosolids, which were stored on site in landfill cells along with daily output of CCBs from the mill boilers. A conversion process via the patented pyro-process12 (US Patent No. 5,342,442) to produce synthetic light weight aggregates (LWA) from CCBs and paper mill sludge was conceived to process large quantities of both these waste materials. MRL and WRP initiated and formed a consortium that brought together academia, private industry and state agencies to evaluate the production of LWA by the pyro-process. The industry partners included representatives from the power companies, industrial ash generators, expediters for coal ash products, as well as concrete block manufacturers. It was important to welcome interested parties from not only the western North Carolina area and other parts of the state but also from neighboring states including Tennessee, South Carolina and Georgia. Membership of this consortium evolved during the intervening years to include the following participants and supporters: Progress Energy Carolinas; Duke Energy; Santee Cooper; Full Circle Solutions; Land-of-Sky Regional Council; NC Department of Pollution Prevention and Environmental Assistance; Ecusta Business Development Center; Blue Ridge Paper Products; Jackson Paper and Manufacturing Company; Miller Perlite; Appalachian Products; General Shale Brick; Metromont Materials; Small Business Technology Development Center of the University of North Carolina system and North Carolina State University The initial development program conducted at the Minerals Research Laboratory (MRL) was to formulate an acceptable LWA product, which fulfilled user specifications for light weight concrete block and structural concrete application. Support work and program coordination efforts were furnished by retired technical volunteers in WRP. The work advanced steadily, using proven technologies well established in the mineral industry, to generate a very satisfactory LWA. The consortium then concluded that a more comprehensive CCB conversion program would have more appeal for full scale manufacture and commercialization, if a variety of products from CCB separation were generated. This product assortment would include bottom ash, low carbon fly ash, recovered carbon of high purity, as well as the synthetic LWA. The bottom ash would serve the concrete block market, the fly ash was in demand for ready-mix concrete, and the high carbon product could be pelletized and used as a fuel for reburn or by the steel industry, and the LWA was a sought-after component for light weight concrete applications. After scouting all these potential markets and finding them to be viable, the consortium then inaugurated an integrated pilot plant program for the CCB separation and conversion. The plan was organized in three (3) parts: (1) Phase I ? bench scale evaluation studies (2) Phase II continuous pilot plant evaluation and (3) Phase III ? conceptual commercial plant design including marketing efforts and attraction of business entrepreneurs to build a full scale manufacturing plant. Phase II would serve to validate the process in a continuous mode and produce substantial quantities of products for preliminary marketing efforts and for demonstration-of-use purposes. The consortium agreed to the name, CAROLINA ASH PRODUCTS, (CAP), for the integrated pilot plant program. The products generated might be designated with the CAP label as: bottom ash would be named CAP Granules, low carbon fly ash would become CAP Ash, recovered high carbon product would be CAP Carbon, and LWA would have the name CAP Stone. Phase II of the program processed 20 tons (18 t) of ponded ash from Progress Energy storage at a rate of 600 lb (271 kg) of raw ash per hour with favorable results. PRELIMINARY STUDIES Prior to committing laboratory research and development effort as well as support and coordination activities to this program, it was necessary to determine (1) the level of need for a freshly launched CCB reutilization program in this state and (2) what degree of versatility was necessary for such a process. State agency records and a survey of recent boiler operations indicated that in the state of North Carolina at least 77 facilities manage CCBs from their boiler operations. Despite continuing development efforts in more eastern parts of the state, the use of CCBs for commercial applications has not increased to a level which alleviates the need to store vast quantities in private monofills on the generator?s property. More than 1.25 million tons (1.13 million t) of CCBs are landfilled in NC annually, with 300,000 tons (271,985 t) per year generated in western NC alone. Many different boiler types, which span both very old units and those that are modern and efficient, were to be found. These included stoker-fired units, pulverized coal boilers, slag-tap furnaces, and fluidized bed combustion boilers covering a range of sizes. Any systems designed to separate CCB components from all these sources and convert them to useful secondary products would need broad processing latitude and flexibility. Up to the present there has been a paucity of research done in the western part of the state to find productive alternatives to storage in landfills. With tipping fees in our largest landfill now approaching $40 per ton ($44 per t) and escalating transportation fees (about $200 per truckload up to 40 tons, traveling a distance of 25 miles), the problem has become urgent both economically and ecologically. A well-designed, integrated wet process for CCB separation into value-added products had much potential to be less expensive than landfilling as well as to provide saleable materials with acceptable profit margins. These preliminary investigations also revealed that other major waste streams, in particular paper mill sludge and municipal and animal waste biosolids were important candidates for priority attention. Since these biosolids could furnish the organic component of a synthetic LWA product, they could be consumed as part of the same program. This added interest value to a growing list of partners to support and participate in the program.

Jan 1, 2009

By Barun Gorain, Aparup Chattopadhyay

"Many double refractory gold deposits are characterized by the dominance of ""invisible gold"" (sub-microscopic gold) as solid solution or as colloidal-sized particles in different sulfides and other phases. These deposits are mainly composed of silicates and carbonates with moderate clay and mica content and with minor amount of sulfides and organic carbonaceous matters. The presence of highly preg-robbing and finely disseminated carbonaceous matter adversely affects gold recovery in leach circuits. Characterization of carbonaceous matters, commonly known as TCM and quantification of gold associated within these carbonaceous matters along with different sulfide and oxide phases is highly complex and challenging. Studies were initiated on various complex ore deposits and also on samples representing various process streams. This paper presents the development of a systematic approach to gold deportment studies using state-of-the-art mineralogy characterization techniques for quantification of invisible and visible metal contents in various species. The relevance of this mineralogy characterization to metallurgy will also be discussed in this paper."

Jan 1, 2014

By V. I. Lakshmanan, D. A. Mackie

"1. INTRODUCTIONIn the past two decades, low-grade gold and silver ore bodies in the United States have been exploited by heap leaching, primarily with sodium cyanide solutions. This method has proven to be a viable alternative to conventional milling due to its low capital and operating costs. Successes have been made, particularly in Nevada, where ores are well oxidized and the climate is conducive to this method. in recent years, heap leaching has been tried in northern latitudes with some success, however, in using this method, operators face more severe limitations than do their neighbours to the south.This paper evaluates the limitations of heap leaching with particular emphasis on northern climates and introduces an alternative method to recover precious metal values in a continuous vat. This proprietory technology, known as the Mackie Vat Leaching Jig, shows promise, with improved gold recovery and potential to operate in cold climates.2. WHAT ARE THE LIMITATIONS TO HEAP LEACHING?Heap leaching of non-refractory ores is subject to the following limitations:1. Minimum amount of free gold and nuggets in the ore.?. Minerology of the ore--accessibility of gold to lixiviant.3. Minimum particle size and size distribution of crushed product to allow percolation of lixiviant through the heap.4. Minimum amount of clays or clay-like slimes that can cause coating of ore particles and channelling of lixiviant.5. Minimum strength of ore particles or agglomerations to allow economic height of heaps to be built.6. Amount and suitability of real estate.7. Amount and type of precipitation.8. Ambient temperatures.9. Possible poorer lixiviant diffusion.10. Possible lower oxygen content in dissolved cyanide solution with higher heaps, particularly with ice and snow cover."

Jan 1, 1989

By M Rayner, C Tsouris, A Komelkov

X-ray fluorescence (XRF) is a widely accepted technique for the elemental analysis of iron ores and their concentrates. Wavelength-dispersive, or WDXRF, and energy-dispersive, or EDXRF, spectrometers offer distinct advantages for particular applications, elements and concentration ranges and are, therefore, more complimentary than people might realise. A key example is the ability of EDXRF to identify, and often quantify, unexpected elements in production samples that would typically be missed by routine WDXRF. In this paper we discuss recent technological advances in XRF and present a novel application example that demonstrates the additional technical and practical benefits of using both EDXRF and WDXRF to characterise iron ores and concentrates.CITATION:Tsouris, C, Komelkov, A and Rayner, M, 2015. A novel approach to the characterisation of iron ores and concentrates using recent advancements in wavelength- and energy-dispersive x-ray fluorescence spectrometers, in Proceedings Iron Ore 2015, pp 591–594 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Sridhar Krishnan

This paper presents the results of a comprehensive pre-production pile testing programme for the US$ 800 million 1400MW Coal-Fired Jimah Power Plant Project in Negeri Sembilan, Malaysia. The testing programme included high-strain dynamic testing and fully instrumented static axial and lateral load testing of driven prestressed concrete piles and bored cast-in-place piles. A highlight of the testing programme was the pioneering use of the Global Strain Extensometer (GloStrExt) Method, a deformation monitoring system that uses advanced pneumatically- or hydraulically-anchored extensometers and a novel analytical technique to monitor loads and displacements down the shaft and at the toe of driven prestressed concrete piles. The experience with the testing programme for the Jimah Project also demonstrates the possibility of achieving notable breakthroughs, not only in the monitoring, evaluation and reporting of pile foundation behaviour dynamics but also in our understanding of the mechanisms that underpin such behaviour. These significant gains are undeniably a direct result of the committed and co-operative relationship among the project owner, design/builder, specialist piling subcontractors, pile suppliers and pile instrumentation and testing specialists.

Jan 1, 2006

By A Tawadrous, D S. Preece

Cave mining is of interest to the mining community as it offers a chance to extract large, deep orebodies with low operating costs and high production rates. It allows for extracting large low-grade orebodies, which may not have previously been considered for mining. Cave mining is done either top down (ie sublevel caving) or bottom up (ie block/panel caving). Both approaches rely on gravity, stresses and weakness of the rock to fracture and achieve a controlled collapse.Block caving starts at the base of the orebody. It progresses upward and across through continuous collapse of the roof. To achieve this, a critical hydraulic radius must be exceeded. This is accomplished by blasting drawbells, through which the caved ore passes to the production level. An entire level above the drawbells (undercut level) is excavated to help initiate the cave. The undercut level ensures the connection between drawbells and achievement of the required hydraulic radius.Conventionally, drawbells are generated by drilling and blasting several times from the production level as well as the undercut level. Mucking between each shot is required to generate enough void space for the rock to swell. The need for several blasts necessitates some downtime between each blast. Also, the cost of developing and maintaining the undercut level can constitute up to 35 per cent of the cost of mining the panel.A new blasting technique was developed to create the drawbells in a single blast from the production level. The technique ensures the connection of the drawbell to the neighbouring ones, thus, the critical hydraulic radius is reached and propagation of the cave achieved without the need for the undercut level. The technique has the potential to reduce the capital cost of a block caving operation, increase its feasibility and reduce time to reach the ore and consequently the payback period. This paper presents the modelling of a traditional drawbell excavation process, the philosophy of the developed technique, the modelling of that new design and its implementation.CITATION:Tawadrous, A and Preece, D S, 2015. A novel blasting technique to create drawbells and eliminate the undercut level in block cave mining, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 617–624 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Y. Bai, J. J. Liu, D. Q. Li, S. Z. Liu, X. T. Wang

"This paper presents the results of an industrial test using 8 t/d of Baotou concentrate (50% REO) of a clean metallurgical process, which includes: 1. Roasting with H2SO4 at low temperature (220~260 0C) in a batch roasting furnace followed by water leaching to obtain a leach liquor as feed with a yield of >95% RE and Th, recovering F as fluoride, producing a leach residue amounting to 1/3 of an equivalent high temperature residue and containing <0.03% Th and radioactivity < 3×104 Bq/kg compared to the normal high temperature residue containing 0.2-0.3% Th and 1×105 Bq/kg. 2. Separating Th with N1923 and extracting RE by P507 has been completed in mixer-settlers. Test results indicate that the ThO2 product has a purity of > 95% with a yield of 99%, and the RE has a yield of >95%, in which ThO2/REO <5×10-6, and that P507 loaded RE connect straight with separating RE using P507-HCl system. 3. Treatment and multipurpose use of "three wastes" (water, gas and solids) are discussed in some detail."

Jan 1, 2014

By R. K. Mehta

An accurate, efficient and stable computation of the mill matrix function (eAt) is needed where mill matrix (A) is a real general matrix. Two important modeling cases in comminution where such need arises are: Heterogeneous comminution behavior of multi-component ores and ultra-fine grinding involving simultaneous attrition and fragmentation breakages. This paper presents the application of a novel splitting method in conjunction With similarity transformation technique in the form of "product formula" which is found to work in all cases and uses a most aggravating, yet interesting property of the matrix exponential in a restricted sense. Results are presented showing that this method can yield solution as accurate as those obtained With an analytical technique. The utility of this computational approach is demonstrated by parameter estimation analysis using a distributed component model in the liberation area through computer simulations.

Jan 1, 1992

Acid generation from reactive sulphide mineral tailings has become a major environmental problem in the mining industry. Initiation of chemical and biochemical oxidation reactions of the sulphide mineral leads to acid generation. A novel concept of safe disposal and utilization of reactive fine mill tailings is presented in this paper. The paper also presents the results of a preliminary laboratory experimental .study of the concept. The tailings are agglomerated using portland cement as a binder. The cold bonded agglomerates are encapsulated with other chemical additives to act as acid neutralizers, oxygen and ironoxidizing bactericides., The primary. factors influencing the choice of bacterfoides to inhibit the acid generating bacteria are their costs, toxicity and environmental friendliness. The paper discusses the utilization of agglomerated&apos; products as aggregates for underground backfill, or as gravel for surface land cover.

Jan 1, 1991

By J. Scheepers, P. Smith, G. (Yunfei) Qiao

High pressure acid leach (HPAL) and pressure oxidation (POx) or pressure leaching extraction processes occur in autoclave vessels operating at elevated temperature and pressure, acidic conditions with abrasive mineral slurries. The harsh process conditions require specialized severe service metal seated ball valves to support operation of the vessels. Over several decades thermally sprayed titanium dioxide (TiO2) and chrome oxide (Cr2O3) coatings have been applied to extend the service life of the ball valves and other high wear critical components. Variability in the coating application quality control and severe process conditions can result in spalling, coating failure and premature failure of the component resulting is decreased autoclave circuit availability. In 2012 MOGAS, together with BRENCO, initiated research and development for ML-381, metallurgically bonded coating. This paper includes the historical development of severe service ball valve coatings, success of the trials and increasing industry adoption of the ML-381 coating for ball valves and other critical autoclave circuit components.

Mar 2, 2022

A Novel Diagnosis and Evaluation Procedure for Flotation Plants

Sep 13, 2010

By B. K. Parekh

Sludge obtained during production of magnesium (Mg) metal from electrolyzing of molten MgCl2 contains entrapped magnesium particles. The sludge material containing the magnesium particles is a friable, continuous matrix of frozen salt mixture which may also contain some oxides and impurities. A dry process was developed for recovery of magnesium metal from the sludge, utilizing minerals beneficiation unit operations. The steps included selective comminution, screening, attritioning and tabling. Recovery of the high grade (+90 percent) metal was in the 70 percent range. The process is being commercially used in the U.S. The novel process was also successfully applied to a magnesium-alloy for recovery of metal from the sludges.

Jan 1, 1995

By Nicole de Jager, Michael J. Nicol

"In order to liberate gold from refractory gold ores and concentrates it is generally necessary to oxidise the surrounding sulphide minerals, typically pyrite and arsenopyrite. Traditional methods of oxidation include pressure leaching, roasting and bacterial oxidation. In recent years, bacterial and pressure oxidation have found increasing favour, although these methods are by no means completely satisfactory and each is subject to particular disadvantages.A novel process has been developed as an alternative to the traditional methods whereby electro-generated ferrate(VI) ions in alkaline solution are used to oxidise a pyrite concentrate. This process has been observed to proceed fairly rapidly and could prove to be a more economically viable process, as well as being more environmentally acceptable. As an added benefit, operating in an alkaline environment is advantageous for downstream cyanidation processes.Ferrate(VI) is a relatively unknown species, due mainly to its instability in acidic solutions. However, in alkaline solution it has been observed to be sufficiently stable for use as an oxidant when used under favourable conditions. Ferrate(VI) is most conveniently manufactured electrolytically via the dissolution of high-carbon anodes in strongly alkaline solutions. Some literature has been published on the electrolytic generation of ferrate(VI) and relatively high efficiencies have been observed by both the authors and other researchers.This study utilises both electrochemical techniques and leaching experiments to examine the kinetics of the oxidation of pyrite by ferrate(VI), which is produced electrolytically. Cyclic voltammetry, rotating disk voltammetry and potential step experiments have been used to investigate the kinetics and mechanism of the oxidation process."

Jan 1, 1997

This paper presents the results of an experimental study undertaken to demonstrate the feasibility of using silica sand as a grinding media in stirred ball mills for ultra-fine coal grinding. Laboratory batch as well as bench scale continuous tests indicate that the use of silica sand can reduce the energy consumption by 50% and more over its steel media counter-part. Moreover, this approach has been found to eliminate the disadvantages observed with grinding using steel media such as high replacement cost, contamination of coal through media wear, greater degree of coal oxidation due to higher slurry temperature and greater level of noise dissipation. Additionally, coal-sand attrition system reduces the manpower time required which is often spent towards cleaning and storing of steel media in inert atmosphere to avoid rust and corrosion problems.

Jan 1, 1991

By O. G. Olvera, E. Asselin, D. Rival

Particle concentration distributions in a leaching tank have been estimated using a novel experimental approach that takes advantage of the galvanic interactions that occur between pyrite (FeS2) particles and a Pt electrode. The collision of FeS2 particles with Pt changes the open circuit potential measured with the electrode due to galvanic interactions. To discern particle collisions with the Pt electrode from experimental noise a simple analytical procedure was first adopted although the use of techniques involving frequency domain analysis is also briefly presented and discussed. Although this method is still under development, it is simple to implement and can yield valuable information regarding the hydrodynamic behavior of solid particles in stirred tanks in very short times. Finally, the advantages and drawbacks of the technique are discussed.

Jan 1, 2014