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By N. Ahmed

"This paper is concerned with the drainage behaviour of gangue mineral in the froth phase. Experiments were carried out in a continuous laboratory flotation cell in which froth depth and bubble size can be changed independently. The fraction of solids returning from the froth to the pulp zone was expressed using a rate constant by considering the appropriate froth regimes. A mixture of hydrophilic solids (silica) and floatable particles (glass ballotini) was used as a flotation feed. Samples of glass ballotini of different hydrophobicities were obtained, using controlled silanation. Three samples, with contact angles of 50, 66, 82 degrees, were used. The effect of the initial bubble size (pulp bubble size), concentration of gangue mineral in the froth zone, and froth depth on the drainage of silica, were also investigated.Typical results obtained from this study is shown in the figure given below. In this figure drainage rate constant for the entrained solids in the presence of particles of the three hydrophobicities is plotted against froth height. As observed, the drainage rate of the entrained solids increases considerably with an increase in the degree of hydrophobicity. Concerning the effect of pulp bubble size on the drainage rate of entrained solids, larger bubbles always give higher drainage rates due to formation of relatively loose froth structures which allows gangue particles to easily move down to the pulp zone. Conversely, smaller bubbles exhibit lower drainage rate constants, in particular at shallow froth depths."

Jan 1, 2003

By Barbara Peszko, Tadeusz Tumidajski

"Various methods are used to identify the grain composition of fine-grained materials because so far the best notion of the grain size has not found and there is no single method to define grain size. In practice the most important are the following grain sizes: sieve diameter dt, effective diameter de, substitute diameter d2 and statistical diameter dst. The mentioned sizes are connected with the methods of analyses. Methods are correct but measure of different diameters of grain and their results are different.The most important methods of granulometric composition analyses are the following: the sieve analysis, the sedimentation method and the conductometric (Coulter-Counter) methods. In each of these methods various physical features connected with the grain size are measured.Sizes of grains defined by different formulas or measurement methods are associated mutually by dependencies, which are results of differences in their determination or calculation ways.In order to determine principles of results comparison the classification analysis results on linearly or non-linearly connected was made. Analyses which results demonstrate the same type of grain size distribution are treated as linearly connected. It is based on the general formulae which determines the probability density function of random variable which is the function of another random variable having the known density function.In order to show the difference in the grain composition of the same material qualified by different methods, three methods of investigations were distinguished. They are: the sieve analysis performed on precise sieves, the sedimentation analysis performed by means of a sedimentation balance “Sartorius” and the microscopic analysis performed after preparing a microscopic slide where the grain size was measured by the Martin’s method.The materials selected for the analysis were quartzite and glass, which are the material of high purity.The obtained results of mentioned above three types of analyses were approximated by distribution function of four distributions: Weibull, log-normal, cut Weibull and Gaudin-Schuhman."

Jan 1, 2003

By G. M. Wolfaardt, B. C. Qi

"From a lifecycle point of view, biologically digested sludge is a valuable product that should be reused if possible. In contrast to landfill and incineration, application of digested sludge comprises the recycling nutrients and organic matter and reflects the policy of resource conservation and sustainability in waste management. Sludge may be applied to agricultural land for further sludge treatment and improvement of the characteristics of the soil. The characteristics of sludge that affect its applicability for soil conditioning include moisture content, pathogens, nutrients and metals. In this paper, the use of solid anaerobic digestion sludge of the lignocellulosic residues to condition soil was investigated in regards to nutrient composition, water content/retention capacity, hygienic quality (contamination of pathogenic bacteria) and heavy metal adsorbing/releasing characteristics of the sludge.The digested sludge had approximately 44.5% free and immobilized water and 46.9% bound water. The water-holding capacity of the sludge was high. This was the first merit to apply the sludge to agriculture in dry areas. Secondly, the sludge was rich in macro-nutrients (N, P, K) and a series of micro-nutrients (Ca, Mg, Mn, Na, Fe, Cu, Zn, B). The water-soluble fractions of macro-nutrients in the sludge were found considerably low. This implied that the loss or leaching of the macro-nutrients from the anaerobic sludge to the aqueous environment be slow. The nutrients loss owing to leaching could be reduced. However, because of a lower macro-nutrient content of the anaerobic sludge, comparable to the chemical fertilizer, it is advisable that the anaerobic sludge be applied together with commercial fertilizer to the agriculture land. Thirdly, the anaerobic sludge had strong selective adsorption affinity for heavy metal ions; non-heavy metal ions such as K(I) and Ca(II) could be released easily from the sludge in a wide pH range, such as pH from 1.0 to 8.0. Since the metal toxicity to the environment mainly comes from the mobile heavy metal ions, the selectivity to adsorb heavy metal ions of the anaerobic sludge can be utilized to reduce the availability of heavy metal ions to plants and humans in aquatic environment. Fourthly, the anaerobic digestion under thermophilic conditions showed a promising disinfecting effect to the sludge, in contrast to the landfill digestion."

Jan 1, 2003

By Nicolás Luis, Qi Liu, Gonzalo Montes-Atenas

"The prediction of froth flotation performance is still an unresolved topic. Classic industrial models based on particle size, elemental and mineralogical information provides recovery results with deviations that may become significant. One possible reason for this deviation may be the fact that the current liberation analysis provided by electron microscope based techniques does not take into account the outmost surface layer composition of liberated particles. In order to complete the description provided by the liberation analysis, other spectroscopy techniques measuring the extreme surface of the minerals can be tested. For instance, X-ray Photoelectron Spectroscopy (XPS) is a technique which measures the first tens of nanometers providing elemental composition over the particle surface and allows resolving the elemental associations present at the surface sample. However, this information needs to be statistically robust, reproducible and most importantly representative of what is occurring in the process. The aim of this research work is to develop a statistical model based on particle population to evaluate the feasibility of turning the XPS technique into a metallurgical tool. The model consists of classic statistical population arranged in a bed of heterogeneous particles with a known grade and mineral liberation. The simulations showed that the XPS results statistically followed a well-defined pattern. The statistical results were confronted with pilot plant results obtained from a rougher bank when processing a copper sulfide ore from a Chilean mine site. It was observed that the probability function distribution was in agreement with the experimental data. Further analysis on how the XPS results provide valuable information improve the computation of froth flotation recoveries is also discussed."

Jan 1, 2014

By M. Brennan, A. Majumder

"The mineral processing research community has devoted enormous efforts to the modelling of mineral separators over the last 50 years. While many efforts have been made to use only fundamental physics as a basis for the models, fluid flow patterns in separators are not simple while the motion of particle swarms through fluids is extremely complex.Sluices are the simplest forms of the flowing film concentrators and have been used in the mineral industry since at least the 15th century (Agricola, 1556). Flowing film concentrators, in general, still have widespread applications in the mineral industry and their designs vary according to the specific need.Particle separation in a sluice appears deceptively simple, but the separation mechanism has proven complex and difficult to quantify. Separation in the sluice takes place in a flowing film a few millimetres thick. The particles are suspended by turbulent eddies and motion relative to the fluid takes place in socalled hindered settling mode. The difficulty arises because the presence of the particles influences the flow pattern and when the particles are fully transported by the flow, the flowing slurry may not have the same viscosity as water and does not have the same density. For this reason a universal theory which can explain the behaviour of a suspension in a sluice or any other gravity equipment has still not been developed. Few attempts have been made to analyse the mechanisms involved in the concentrating processes of pinched sluices and Reichert cones.Fluid flow behaviour and slurry transportation characteristics in open channels have, however, been active research topics in the disciplines of fluid mechanics, chemical engineering and civil engineering for many years. As a result, an extensive literature is available, which has led to the development of the model described in this paper.In an effort to test the extent to which fundamental fluid mechanics can provide a prediction of particle separation, a study on a simple parallel-sided sluice has been carried out using glass beads at various particle concentrations and flow rates, and the actual particle separation taking place compared to predictions from modelling.The modelling strategy was divided into two parts; the first was to predict the horizontal slurry flow velocity profile and the second to predict the solid particle concentration over the depth of the flow at different flow conditions. The predictions were then validated with measured data sets. This can easily be done if the slurry flow is split at different fractional flow depths so that the mass flow of solids over different flow heights is measured accurately over a fixed period. Mass flow splits can then be calculated by integrating the product of the predicted slurry velocity profile and the predicted solids concentration profiles from the base of the sluice bed to the slurry free surface."

Jan 1, 2003

By Thomas Pretz, Alexandra Pehlken

Sampling of municipal solid waste is known to be difficult to sample if it has to be representative. When dealing with municipal solid waste, the usual method is to study separately waste material below 40 mm and particles bigger than 40 mm. The material < 40 mm cannot be sorted manual and is termed the “fine fraction”. The particles > 40 mm can be separated manually and are usually sorted into pre-defined groups of materials. These groups can be defined depending on the demand of quality assurance. But standardisation of procedures is not far progressed, even for the widely practised sorting methods.

Jan 1, 2003

By R. Van Hille, A. E. Lewis

"The precipitation of a selection of metals from both a synthetic and an actual metal-rich effluent was investigated. The experimental aspects of this study were carried out in a two-stage process consisting of a pre-treatment clarifier and a fluidised bed (pellet) reactor. Each unit operation in the two-stage process was investigated separately. The pretreatment clarification stage at pH ˜ 5 resulted in a 99.9% removal of iron and 97.3% removal of aluminium.The pellet reactor was used to precipitate nickel as nickel hydroxy-carbonate from a pure stream and a removal efficiency of 99.6% was achieved. The high local supersaturation at the reagent inlet points caused the formation of a large amount of fines, but these agglomerated onto the pellets up the length of the bed (See Figure 1).For copper precipitated as copper sulphide from a pure stream, a maximum removal efficiency of 92% was achieved. The high local supersaturation at the reagent inlets also caused the formation of a large amount of fines, but the extremely sparingly soluble nature of copper sulphide meant that the fines were not agglomerated up the length of the bed. In Figure 2, the global supersaturation ratio was relatively low, and thus there is little homogeneous nucleation and degree of fines formation. However, the fines occurring after the third sulphide input point (at 30cm from the bottom of the bed) indicate that local supersaturation also plays a critical role in fines formation. It was therefore concluded that, for the copper sulphide case, it is essential to control the supersaturation at the inlet points in order to prevent fines formation altogether, as it is not possible to agglomerate the fines once they exist in the bed."

Jan 1, 2003

By R. Van Hille, S. Lacour, A. E. Lewis, K. Peterson

"This paper compares thermodynamic modelling results with those obtained for copper sulphide removal from aqueous solution in both continuous and batch experiments at laboratory scale. Sulphide precipitation has been demonstrated to be an effective method for heavy metal removal. The advantages are the high degree of metal removal at low pH, low quantities of sludge formation, the ease of de-watering and low reactor retention time due to high reactivity of sulphides. However, the low solubility of sulphide species can lead to spontaneous nucleation of fines, which are difficult to remove.Theoretical modelling was carried out using ASPEN Plus™ and OLI systems Inc ESP process. Both simulators were used to calculate copper sulphide recovery and residual aqueous copper concentrations as a function of pH. The predictions were then compared with experimental results. Both simulations predicted that all of the inlet copper would precipitate as sulphide CuS(s) over the entire range of pH and sulphide: copper molar ratios investigated. The simulation results were strongly influenced by the number of chemical species and the nature of the thermodynamic data taken into account in the model.The continuous experimental studies were carried out in a fluidised bed reactor (FBR). Copper sulphate was reacted with sodium sulphide and the solid precipitated directly onto the pellets in the FBR. The use of sulphide was motivated by high sulphate levels in local acid mine drainage and the ultimate integration of the metal removal process with a biological sulphate reducing process that produces an aqueous sulphide stream.A maximum dissolved copper removal of 99.6% (AAS analysis) and a total removal efficiency of 95.8% (dissolved copper minus fines) were achieved. Stoichiometry of the precipitate was determined from SEM/EDAX analysis (atomic percentages) and was close to 1/1, irrespective of the operating conditions."

Jan 1, 2003

By M. H. Moys, H. Dong

"Discrete Element Method (DEM) has become a standard tool to simulate grinding mills in order to gain information about load behaviour, power drawn, etc. However, parameters necessary to run a simulation are not always readily available. For example, the coefficient of restitution used in DEM simulation from the literature ranges from 0.1 to 0.9 due to lack of accurate values. The lack of correct input parameters results in the fact that some simulation parameters are adjusted to match the simulation prediction with the experimental results. It is inappropriate to tune one single parameter arbitrarily in order to fit the prediction with experimental results. The correct value of parameters for DEM simulation should be established, and rigorous validation on simulation results by DEM needs to be done.The objectives of the ongoing project are to measure the coefficient of restitution at conditions analogous to grinding practice. Equipment has been built to measure the coefficient of restitution. A typical case of impact test showing the vertical position of a ball as a function of time is presented in Figure 1. The coefficient of restitution between steel ball of different sizes and the targets including steel liner (e = 0.91), mild steel block (e = 0.57) and rubber liner (e = 0.7) have been measured. The coefficient of restitution reduces to 0.38-0.52 when there is a layer of coal particles (1-2 mm) on the steel liner. The effects of ball size, drop height on coefficient of restitution are investigated. Then a DEM code is developed of several contact models to simulate the impact process. This code can reveal details on velocities (translational and rotational) and forces (normal and tangential) during the brief impact interval. Figure 2 is a comparison of the rebound rotational velocity between experiment and prediction by different models. The results can be used as DEM input and to assess contact models."

Jan 1, 2003

By Bertil I. Pålsson, Sture V. Persson, Kent T. Tano

"Autogenous (AG) and semi-autogenous (SAG) mills often operate in an unstable state because of the difficulty to balance the rate of replenishment of large ore particles from the feed with the consumption in the charge. This has led to an increased interest in obtaining an accurate and direct measurement of mill load and the behaviour of the mill charge. A problem in attempting to measure those parameters is getting a sensor that is both robust and sensitive enough for continuous on-line measurement.Techniques that measure the force acting on the lifter when it hits the charge inside the mill have got an increased interest recently because of the ability to combine it with DEM modeling. This paper presents a method for the measurement of the apparent filling level in a pilot ball mill equipped with the Metso Continuous Charge Measurement system (CCM). In this technique a strain gauge sensor is mounted on a flat steel spring which is fitted into a recess underneath a lifter bar. In addition, a conductivity probe, the Boliden Grinding Measurement System (GMS), is mounted in another lifter bar with the purpose of comparing the two measurements. To visualise the behaviour of the charge a 2D DEM modelling technique is used with Metso HFS software.The pilot mill is a grate-discharge mill, equipped with 12 rubber lifters of square size 0.1 m, face angle 45 degrees. Steel balls in the size range 10-30 mm and density 8000 kg/m3, are used in the experiments. Test material is a hematite pellet feed, d50 around 45um, chosen to get stable grinding conditions with respect to feed size variations.The experiment is meant as a first test of the equipment’s performance, and to study how the sensors respond to changes in some operating variables. To get an understanding of, and distinguish between correlation and causality, experiments are performed according to a full factorial design with two levels, and in addition two replicates of the experiments at a center-point in the charge level setting."

Jan 1, 2003

By S. S. Indi, D. Santhiya, S. Subramanian, K. A. Natarajan

"With the gradual depletion of the high-grade ores and finer dissemination of values in the leaner samples, it has become imperative to develop innovative approaches to process such complex ores. The beneficiation of complex sulphide ores containing copper, lead and zinc minerals, remains one of the most important challenges in base metals metallurgy. The advent of biotechnology in mineral processing has opened up immense possibilities to exploit such difficult-to-treat ores. Bioprocessing techniques thus hold promise as potential substitutes for the conventional technologies in vogue. Several types of autotrophic and heterotrophic bacteria, fungi, algae and yeasts are implicated in mineral beneficiation processes. Adopting a bioprocessing route to mineral beneficiation has attractive benefits, such as lower cost and energy requirements, environmental acceptability and operational flexibility.The interaction of sphalerite- and galena-adapted Bacillus polymyxa (B. polymyxa) cells with sphalerite and galena has been investigated through adsorption, electrokinetic and flotation studies. The amount of sphalerite-adapted cells adsorbed onto sphalerite and galena is found to decrease with increase in pH. On the other hand, the adsorption density of galena-adapted cells onto galena shows a feeble maximum around pH 8, and the amount adsorbed is marginally higher in the pH range of 8 – 11.5. In the case of sphalerite the amount adsorbed is higher in the pH range of 5 to 7. The adsorption density of both the adapted cells is higher for galena vis-à-vis sphalerite. Electrokinetic studies indicate significant surface chemical changes on the chosen sulphide minerals and the bacterial cells, consequent to microbemineral interactions. Selective flotation tests on a synthetic mixture of galena and sphalerite confirm that sphalerite could be preferentially floated from galena, using galena-adapted cells, but not with the sphalerite-adapted cells. The cells adapted to galena assay a higher polysaccharide content and are more hydrophilic, while the sphalerite-adapted cells have a higher protein content and possess greater hydrophobicity. Transmission electron microscopic studies have provided evidence in support of the differences between the cell surface characteristics of sphalerite- and galenaadapted cells (Figure 1). Possible mechanisms of interaction between the minerals and the bacterial cells are discussed."

Jan 1, 2003

By Javier Baladron, Mijail Villar, Brandt Henriksson

"In this presentation an overview will be given of what has been observed by the authors in the copper concentration industry, with a large diversity of tailing thickeners operating under different conditions, although many of them are located in the same neighborhood. A closer look will be taken at the reported performance from different sites and from different thickener designs, either conventional or high rate, including those that were retrofitted, regardless of the thickener brand. An analysis is also made of the generic correlation of the size of the thickener and the performance in terms of solids loading (or unit area) and % solids. The paper envisions a technology development route, makes a brief analysis of the economic impact of the suggested route and points out the need for development in technologies around tailings thickeners, such as automation, yield stress measurement, slurry pumping and construction methods."

Jan 1, 2014

By João Queiroz, Cristian Marquez-Sarmiento, Luiz Teixeira

The removal of various metals from process waters and effluents is usually done by precipitation of the corresponding hydroxide. Manganese however is one metal that does not respond efficiently to that approach. It may be seen in its eH X pH diagram that the way of oxidation to Mn IV rather than hydrolytic precipitation of the Mn II ion as its hydroxide, is the way to efficient precipitation of Mn in the pH range 6 to 10. We studied the use of oxidants O2; NaClO; H2O2; Caro´s Acid (H2SO5) and the combinations of O2 or H2O2 with Na2S2O5, and H2O2 with NaClO, for the oxidative precipitation of Mn from synthetic solutions starting with 10 mg/L Mn, at 25 oC. In adequate conditions, which include pH > 8, it is possible to reach final [Mn] less than 0.1 mg/L in 60 minutes of reaction time.

Jan 1, 2014

By Daniela Campos, Aldo Casali, Gonzalo Montes-Atenas

The understanding of the effect of the major variables influencing the froth flotation performance may allow both to predict and to identify best operating conditions towards optimizing the process efficiency. The aim of this research work is to model the effect of dissolved oxygen onto froth flotation performance. Experimental pilot plant results were obtained from a continuous circuit consisting of a ball mill and a rougher bank of four flotation cells. A series of flotation experiments were run with different conditions of dissolved oxygen keeping constant most of other operating conditions. Variables difficult to control were measured or estimated. A set of mathematical models suggested in the published literature were tested. It was found that the copper recovery results were highly sensitive to the concentration of dissolved oxygen. The latter confirmed the reactions mechanisms associated to the collecting capabilities of current flotation reagents used in the flotation of copper sulfide ores. On the contrary, the results of molybdenum recovery varied non-linearly with changes in dissolved oxygen which could not be explained directly in terms of the computed specific rate constants. The error analysis confirmed that Klimpel continuous model exhibited the best specific rate constant correlation with molybdenum recovery data. Lastly, the classic particle force balance equations indicated that the adjustments of estimated mineral liberation with experimental data exhibited a turning point when passing from highly liberated to low liberated particles. The values of recovery for such turning point correlated well with the concentration of dissolved oxygen. The results indicated corrections due to changes in the dissolved oxygen must be incorporated in future froth flotation descriptions.

Jan 1, 2014

By Przybycien Krzysztof, Tumidajski Tadeusz

"Materials being the feed to mineral dressing plants are the mixture of ore minerals having different physicochemical properties among others, especially susceptibility on crumbling. During exploitation of material and their preparation to communition the big number of narrow classes comes into being and they have different properties. The determination of common communition laws of multicomponent (on account of size and mineralogy) materials leads to the estimation of mutual influence of narrow classes and their rates, taking into account their endurance and mineral density, on general ratios and their simultaneous crumbling.If we try to accept the grain membership to the certain component as the differing feature, we can write the balance equation as: ( ) ( ) S= = k i i i g x p f x1where: fi – density functions of one type distribution and of different statistical moments (characterising the homogeneous materials grinding), pi – “stirring” proportions of each components, S== k i i p 1 1 . From the point of verification view of detailed versions of this equation the inverse operation should be done: in the base of the components’ mixture grinding results and the results of components grinding the legitimacy of equation should be checked.The using of finished distribution mixtures’ theories to the grinding process analysis allows, first of all, to verify the assumption of grinding independence of individual feed components. Talking more generally it would lead to the comparison of grain size distributions, obtained by individual components grinding from the defined in the mixture distributions theory calculations. One of experimental and calculation results for artificial mixtures of galena and dolomite is presented on figure below (df means distribution function)"

Jan 1, 2003

By Heribert F. Broicher, Arne Volland

"The analysis of laser-induced fluorescence (LIF) combines remote sensing techniques with laser spectroscopy. Over variable distances different rock types are identified or changes in the quality of one rock type are recognised. LIF Analysers operate non-destructive, non-contact, on-line and in real-time. Installed over conveyors or over driveways the analysers ""look"" at the moving bulk solids 20 times per second and provide in real-time information for downstream sorting, blending or optimisation of processing. LIF Analysers recognise rock types (hardness information or dilution control), degrees of alteration, degrees of oxidation and –semi-quantitative- content of certain minerals in an ore. Only under favourable conditions quantitative assay information can be obtained, as e.g. the phosphorus content of Kiruna type iron ore.The main application of LIF Analysers is seen in big open pit operations, where the muck is trucked to an in-pit crusher and the crushed rock conveyed out of the pit to its respective destination: e.g. the primary high grade ore to the mill, the low grade or oxidised ore to the leach pads and the internal waste to the dumps.In underground mining and especially in block caving operations dilution control is of utmost importance. Here a LIF Analyser mounted on the back of a pick-up truck can be moved from drawpoint to drawpoint and quickly assess the degree of dilution.Closer to the mill the stockpile management based on LIF analysis will lead to stockpiles sorted according to rock type (hardness), degrees of alteration and oxidation. In case of direct feeding rom ore to the mill the knowledge of the type and quality of all the material between the in-pit crusher and the mill facilitates optimisation of e.g. reagent dosage."

Jan 1, 2003

By Andrew D. McCallum, Russell A. Heins

"Until the advent of intensive cyanidation, gold gravity concentrates were generally treated by tabling. The table concentrates were smelted while table middlings and tailings were recycled to the milling circuit for further grinding and subsequent leaching in the CIP/CIL circuit. Gold recovery on production tables is relatively low, often only 30 percent, and rarely above 60 percent. Significant factors in tabling performance are; mineralogy and the operator’s experience and ability. Units have been developed by Gekko Systems to treat both batch and continuous gold concentrates. Unit sizes are determined by leach kinetics and the required residence time of the concentrate in the unit.Gekko commenced the commercialisation of intensive leaching of gravity gold concentrates in 1997 with the first commercial prototype of the InLine Leach Reactor (ILR). Over 20 units are now installed worldwide with half that number on the African continent. South African mines, South Deeps (Placer Dome WAJV) and Target (AvGold) have both installed InLine Leach Reactors. Ashanti Goldfields have placed the ILR on their standard equipment list and have six operating units with a seventh on order. AngloGold installed one of the first ILR production units at Morila in Mali.Gekko Systems successfully installed an ILR1000 Batch unit at the Antapite Mine in Peru in December 2002. The unit was installed to treat gravity concentrates and to replace a shaking table. Following installation, gravity gold recovery increased from 15% to 40% of total gold. The unit was operational from start up and the first gravity batch treated achieved 98% gold recovery. The gravity concentrates also have a high silver content and 95% recoveries on silver were also achieved.Preliminary testwork identified that the concentrates required additional oxygen to achieve peak performance. As a result of optimisation work in the laboratory, leach kinetics in the ILR have been excellent with only 6 hours residence required to achieve maximum gold extraction."

Jan 1, 2003

By E. V. Manlapig

"Some researchers postulate that the floatability of a particle in the streams of an industrial flotation circuit is a function of only its size and liberation properties. They do not discount the importance of reagent or surface contamination on particle floatability but assume that the reagent coverage or surface contamination of the particle surfaces is essentially uniform for particles of similar size and mineralogical properties when subjected to a particular chemical regime.In this paper, samples collected from laboratory batch flotation tests performed on different streams of Cominco Teck’s Red Dog lead cleaning circuit have been characterised with respect to their size, mineral association and mineral surface exposure. An analysis of this data set indicates that the flotation rate of a particle in an industrial flotation environment is a strong function of its size and also of the mineral composition of its surface (Figure 1). It is a function not only of the proportion of the most floatable mineral on its surface but of the floatability of the other minerals on its surface as well.Nodal analysis is a technique developed by the authors that can be used to determine if the ore floatability of a particle class is changing within an industrial flotation circuit. This technique is used within the paper to show that the floatability of all the different types of particle classes studied within the Red Dog circuit did not change significantly during the lead cleaning stage. However, it was also concluded that particles with the same size and mineral composition did not all float with the same rate in the individual streams of the flotation circuit, but with a distribution of rates. It is suspected that the particles within a size mineralogical class in this study have varying degrees of surface oxidation and that this results in varying particle flotation rates. Thus basing particle floatability on size and mineralogical effects, alone, in a flotation model is not always valid."

Jan 1, 2003

By Alim Gül, Güven Önal

"Recently, there have been some attemps on the treatment of low grade ores and old plant tailings due to the decrease in high grade ores and the increase in the metal consumption with increasing world population. Cost of mining and beneficiation of low grade ores become prohibitive since the costs of grinding before flotation make the process unfeasable. Therefore, preconcentration of these ores prior to flotation becomes more important. The concentration of ores preconcentrated in coarse sizes provides a decrease in investment costs as well as grinding and flotation costs. Additionally, the requirements of less space for tailing disposal and less reagent consumption are also important from the viewpoint of environmental considerations.In this study, ore sample containing 0.6 % Cu and taken from Küre-Asiköy ore body was used. Ores contained chalcopyrite and pyrite as main minerals and diabaz, quartz, chlorite and sericite as gang minerals.Samples were all crushed under 9 mm by considering the preliminary studies and float and sink experiments were carried out with the sample in the size range of –9+1 mm using different densities of heavy liquids. As a result of these tests, it was shown that 60 % of the material should be discarded as tailings with 0.1 % Cu content. By considering float and sink test results, the following experiments were performed by using heavy medium cyclone and jigs.As a result of heavy medium cyclone tests, which are conducted on the sample in size range of –9+1 mm, 57 % of the feed material was discarded as tailing with 0.08 % Cu content and 7 % Cu loss, while a concentrate containing 1.43 % Cu was produced with 93 % efficiency (Table 1). Jig tests were done with the samples in the size range. As a result of jig tests with –9+1 mm size group sample, approximately 46 % of feed material was discarded as tailings with 0.13 % Cu content and 10.6 % Cu loss, while a concentrate with 0.94 % Cu content was obtained (Table 2)."

Jan 1, 2003

By Nóra Schreithofer, Kari Heiskanen

"INTRODUCTIONThe knowledge of the adhesion forces between particles and bubbles is of key importance in the improvement of flotation models. The development of the Colloidal Interaction Force Measurement Apparatus (CIFMA) opened the possibility to quantify the adhesion forces between particles and bubbles. The aim of this study was to examine the effect of three main variables: the approach velocity, the loading force and the loading time on the adhesion force between an air bubble and a hydrophobized silica particle."

Jan 1, 2003