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By P. Basarova

The attachment of bubbles onto a collecting surface is an ubiquitous natural phenomenon, playing a critical role in numerous practical processes. The goal of the project is to broaden the knowledge about hydrodynamic interactions between small bubbles and large solids that occur in nature and industrial processes. Focusing on collision processes between a single rising bubble (Db<1 mm) and a larger falling spherical particle in stagnant liquid, the theoretical model describing the bubble trajectory is given here. The model is based on analysis of forces acting on the bubble, and utilizes equation for the bubble motion. Mobile and immobile type of bubble surface mobility are considered. The calculated results are compared with the experimental data; here a high-speed video camera was used to capture the bubble motion and bubble-particle interaction. Very good agreement between experimental and calculated data was found. For both types of surface mobilities, the bubble deviation in the horizontal direction is nearly linear. The proportion constant is bigger for immobile bubble surface and increases with the bubble size. Furthermore, particular forces acting on bubble were studied. A similar course of relative bubble velocity and force impact was observed for identical bubble position. For cases when the bubble centre is close to the particle axis, only deflection in one direction is observed. When the bubble is reaching the maximum trajectory, the force ratio is changed. The bubble is firstly pushed away from the particle, but when it is within close distance from the particle, the bubble is pushed towards the particle.

Sep 1, 2012

By W. S. Eu

Reduction of weathered mineral ores can initiate phase transformation which can affect either their activation or deactivation, subsequently influencing the extent of extraction of desired metals in a leaching reagent. The reduction of ilmenite ores for one occurs as a series of parallel, solid state reactions which at present has no known mechanisms, although the evidence of their effects is abundant. Understanding these reactions may well be the key to uncovering the mechanism of ilmenite activation, hence enabling precise control of its reaction process to maximize yield of TiO2 extraction. However, documenting the solid state reactions in the reduction of ilmenite is challenging due to the ore complexity, the number of simultaneous reactions and the difficulty of capturing critical intermediate reactions and phase transformations during processing. The phase transformations of ilmenite minerals reduced at temperatures up to 850°C were investigated in this study. Mineral transformations were studied in-situ using synchrotron radiation based X-ray powder diffraction with temperature resolved tests. The effect of the extent of reduction and specific mineral transformations were verified by leaching reduced ore with sulphuric acid. The re-sults suggest that transformation of major mineral phases occurs within of specific window of operation and thermal treatment appears to influence the extent of activation and leachability of ilmenite minerals.

Jan 1, 2014

By Claudia Ríos Figueroa, Gonzalo Montes-Atenas

"Among the many variables mentioned in the literature that may influence the froth flotation performance, particle size is perhaps one of the most renowned. Empirical knowledge has indicated that recovery of fine particles will inevitably drop below certain particle size threshold. Several processing alternatives have been suggested to improve the recovery of fine particles. Some of these initiatives have been reached the status of patents and other intellectual property related documents; however, there is still a disconnection between the scientific knowledge available and the industrial operations practicalities implemented to address this matter. In fact, in general terms, none of these ideas or processes concepts have become a final solution to this problem. At first glance, economical reasons may be argued as the main cause hindering the development of these and other ideas, but it would be an oversimplification as technical issues behind them are still themes to be discussed and sorted out. This study aims to review technical aspects behind scientific ideas and processes concepts suggested to solve the problem of low beneficiation of fine particles in froth flotation. The analysis was performed using the theory of inventive problem solving (TRIZ) which allows identifying technical gaps these initiatives have not considered or overlooked. Statistically the scientific databases indicates that reports on fine particles froth flotation only represented less than 50% of all reports involving fine particles processing. Most of the solutions derived from classic contradictions derived from bubbles and particles hydrodynamics only (reducing the bubble size or increasing the turbulence would increase the rate of bubble-particle aggregates formation but may reduce the recovery). This contradiction encompasses a small range of contradictions possible to be accounted and to be resolved. The method is expected to provide insights towards designing definitive solutions for the industry in this field."

Jan 1, 2014

By Samira Rashidi, Robert Dunne, Raj Rajamani

"High Pressure Grinding Rolls (HPGR) are known for more energy saving, better particle weakening and higher tonnage compared to semi-autogenous/ball mill circuits. These machines are scaled up based on the roll diameter. Therefore, studies in lab-scale HPGRs are always preferred because less weight of feed sample is required to run batch tests. The 50-hp laboratory-scale machine at the University of Utah is the first-ever lab-scale machine designed by late Prof Schönert, the inventor of HPGR. This 200x100 mm [DxL] HPGR is equipped with a robust data acquisition system, which enables running steady state tests using a feed sample as small as 6 kg to 12 kg. This paper presents the HPGR grinding study on two different categories of ores, one hard ore and the other soft. A test series has been performed to evaluate the energy consumption and the relation with size reduction on open multi-pass and locked-cycle HPGR circuits. The effect of feed size distribution and operating conditions has been investigated. Locked-cycle tests result in higher reduction ratio and higher rate of fines (100 mesh, 48 mesh and 28 mesh) generation when compared to open multi-pass tests. Data shows that scale-up trend lines stay consistent even when the circuit configuration and operating conditions are varied."

Jan 1, 2014

By T. C. Sun

Two wasted activated sludges (WAS), from an industrial wastewater treatment and a sewage treatment plant respectively, and 7 collectors are used to investigate the feasibility of air flotation thickening of WAS by adding the collectors used in mineral processing. The collectors experimented include straight chain fat acids with different chain length, sodium oleate, alkyl sodium sulphonate, sodium dedecylsulfonate, and dodecylamine. The results show that the thickening efficiency varied depending on different collectors. Of the collectors experimented, dodecanoic acid and dodecylamine are best collector for thickening both sludges.

Jan 1, 2014

By P. Prakash

A dual-drive planetary mill, which has a rotating shaft that sweeps a circle of diameter 750 mm, has been designed. The planetary mill is powered by a 5 hp motor to rotate the main shaft and a 3 hp motor to rotate the jars. The charge dynamics inside the horizontal-axis planetary ball mill was established using three-dimensional DEM simulations. The simulation results provided data to determine the impact energy distribution and the effect of process parameters such as mill speed and filling. It has been observed that the mean impact energy per unit time increases with rotation-to-revolution ratio, whereas the average number of inter-particle impacts per unit time decreases. The mill was also used to synthesize a variety of powders. Here three case studies of reaction milling are briefly presented: (i) cementite and silicon carbide, (ii) oxide dispersed strengthened (ODS) steel, and (iii) magnetite from blue dust. In each case, the powder was produced by mixing and then milling the corresponding pure components. The phase evolution, particle size distribution, and morphology of particles during milling were studied for various samples collected at different milling times using laser size analyzer, SEM, TEM, and Mössbauerspectroscopy. The results established a convenient way to produce powders of high technological and commercial value.

Sep 1, 2012

By Peter Ay, Matthias Schmidt, Christian Stollberg

"The aim of the study is the development of a seamless reprocessing procedure for plastics from automotive parts which are to be recycled (figure 1). Before automatic sorting can be performed, the materials first have to be identified by a near and middle infrared (NIR/MIR) system.Materials reprocessing basically includes research on size reduction, decoating, and roughening of the materials. Variants of the necessary technologies such as different shredders and mills and physico-chemical or mechanical decoating and roughening procedures together with the fundamental approaches underlying these methods are investigated and benchmarked. This allows the theoretical determination of the impact of each method not only on the overall process but also on the result achieved within the identification and sorting procedures."

Jan 1, 2003

By G. Merazchiev

In the selection of copper ? molybdenum concentrates with the use of reagents containing sulfide ion ? sodium sulfide, sodium hydrosulfide etc for depression of copper minerals and pyrites, big part of depressor is oxidized by oxygen, which is dissolving in pulp during aeration with air in flotation machines and it is expended unproductively. This is the main reason for the big expenditures of depressor, reaching up 15~20 kg/t collective concentrate and the high exploitation expenditures for the copper ? molybdenum selection. Effective direction for lowering expenditure of depressor and increasing of the technical ? economical effectiveness of moly production is the conducting of the selection in nitrogen medium. In the paper are shown the results, obtained by applying of this direction in selection of collective copper ? molybdenum concentrate from the porphyry copper deposit ?Ellatzite? ? Bulgaria, in which the ratio Mo:Cu is over 1:120. In laboratory conditions, through comparative experiments in medium of air and nitrogen are defined: expenditure and initial concentration of NaHS in pulp for effective depression of copper minerals and pyrites; kinetics of flotation process of molybdenite; influence of pulp density; emf (negative milivolts) of pulp and the expenditure of nitrogen on tech-nological indexes of molybdenum flotation. When working in nitrogen medium decrease of NaHS in rougher molybdenum flotation from 40% to 45% is settled. When nitrogen is also fed in cleaner stages, the total expenditure of depressor is lowered by 64%. The quality of end molybdenum con-centrate is raised with over 5%. On the ground of the results of laboratory studies and of world practice data, an industrial installation for selection of copper ? molybdenum concentrate in nitrogen medium in Wemco inert ? gas machines.

Jan 1, 2014

By Marianella Perez, Williams Calderón, Gonzalo Montes-Atenas

The lack of fresh water sources, particularly in the Northern part of Chile, has driven the mine sites to search for new and sustainable paths to obtain water resources to run minerals processing operations. Among them, the use of seawater in concentrators appears as an interesting solution to this problem. However, the presence of seawater will have an impact onto the operation, not only because it will enhance corrosion reactions in the equipment installed in a plant, but also because it may affect how particles will effectively be processed across the numerous unit operations existing in the mine site. Among such unit operations, the grinding stage is a highly regarded as it defines the success of the separation of valuable minerals from gangue material in the froth flotation operation. Then, one important aspect to be addressed is to understand how the presence of seawater will affect the different mechanisms acting during the operation of a ball mill. The aim of this research work is to assess the effect of changing the aqueous matrix from process water to seawater in ball mills onto the mill performance. The methodology considered the use of Fluent® software and its capabilities to run numerical simulations with heterogeneous media. On one hand, from the data analysis, it is possible to infer that breakability mechanisms should not be significantly affected. On the other hand, the high ionic strength of the matrix should impact importantly particle transport mechanisms within the mill. Particularly, when transporting finer particles. Rheology results were in agreement with previous published research studies suggesting the suspensions to behave as Newtonian, Dilatant o Pseudo-plastic fluid depending on the amount of fine particles present in the grinding media. The latter will result in changes in the residence time of particles in the mill producing overgrinding or an excess in the circulating loads.

Jan 1, 2014

By M. Ghiani, R. Peretti, S. di Giovanni, G. Zonnedda, A. Serci

"An interesting occurrence of gold bearing ores of economic interest has recently been discovered in the Serrenti- Furtei district, central-southern Sardinia (Italy). The upper part of the orebodies are leaner and fairly porous, and are undergoing intense oxidation processes. In the lower parts sulphide ores predominate, chiefly enargite-luzonite and pyrite and these have a more compact structure. The passage from the oxidized to the sulphide zones, is rather irregular and difficult to delineate. The gold, generally occurring in its native form, is found in small grains. Mineral reserves in the area concerned were originally estimated to total 2.77 Mt: 0.63 Mt of oxide minerals with average gold content of 2.75 g/t and 2.14 Mt of sulphide ores with average gold grade of 3.18 g/t.Recovery of the valuable metals is a complex problem.The effectiveness of a variety of gold extraction techniques has been evaluated conducting tests on batches of ore representative of the different orebody depths obtained from core samples.The techniques investigated were: heap and vat leaching; flotation and flotation followed by leaching of the flotation tailings. The findings indicate that:• the gold contained in the ores in the upper oxidized zones of the deposit can be efficiently recovered by direct cyanidation via heap or vat leaching;• the sulphide ores in the deeper portions, that are not amenable to direct cyanidation but contain enargite concentrations of potential economic interest can be processed by means of flotation to produce a gold/copper bulk concentrate;• beneficiation of the difficult-to-treat minerals contained in the transition zone requires some knowledge of their intrinsic properties. A distinction should be made between the ores containing minor amounts of enargite which appear to be amenable to vat leaching and those with relatively higher enargite content which are processed using bulk flotation of the gold and copper minerals followed by vat leaching of the resultant tailings."

Jan 1, 2003

By Gábor Mucsi, Barnabás Csoke, Viktor Mádai, Zoltán Molnár, Viktor Török, Ádám Rácz

The application of the stirred media mill in dry mode came to the front only in recent years, but at the same time several questions arise, such as aggregation, agglomeration, sticking on the liners and the grinding media. During high energy milling, not only the particle size reduces, but among others, in numerous cases the crystal structure and the amorphous state of the material also change due to the mechanical activation taking place. The present paper deals with experiments carried out on the ultrafine fly ash grinding in dry mode at various grinding conditions in a stirred media mill to investigate the mechanochemical effect and the energy efficiency of the mill. During the experiments the particle size distribution, particle shape, specific surface area, amorphity and crystal structure of the products were examined. The product related stress model was used for the evaluation of the effect of milling parameters on the mechanical activation. It was found, based on the experimental results, that there is mechanochemical effect on crystal structure of fly ash in the stirred media mill, as it was revealed by X-ray diffraction and FTIR measurements. The experimental results made it possible to determine the effect of the rotor circumferential speed and so the stress intensity on the mechanical activation of fly ash could be revealed.

Jan 1, 2014

By John A. Herbst, Ming Song, Xiangjun Qiu

"It has been known for sometime that as wear occurs in tumbling mills there is an associated change in mill throughput. These changes have traditionally been simplistically, attributed to “mill volume effects”. New high fidelity simulation (HFS) tools (involving DEM, CFD and Breakage models) are now giving new “microscale” insights into the complex interactions that occur between evolving lifter/liner profiles and breakage. An illustration of this analysis is shown in Figure 1 below.Here we see that after a new lining is installed (Region I) the wearing process reduces the liner thickness resulting in a larger power draw and an associated higher throughput until Region II is reached. By this point the lifter height is reduced significantly changing charge motion (less cataracting) the power begins to decline, but the comminution efficiency increases with this type of “calmer” breakage environment therefore the throughput continues to increase. In Region III the lifter is no longer providing the minimum required charge lifting action, the power and the throughput both drop off significantly. In the last two stages the behavior is especially complex because throughput is not linearly related to power since grinding efficiency is changing.The study described here shows that these new HFS tools allow the design of wear part profiles which will maximize mill productivity over the entire life of liner/lifter systems. A simple example of such a design procedure is shown involving the selection of a sinusoidal profile for a 34 ft diameter SAG mill.The paper discusses how the principles exposed in this simple example can be applied to search for an optimal profile in which non-standard modifications are allowed to compensate for throughput or wear shortcomings of standard profiles."

Jan 1, 2003

Spent automobile catalyst is an important secondary resource of PGMs (platinum group metals) and the recovery is significant. Various methods of recovery technology have been reported and applied in practical production, including pyro- and hydrometallurgical processes. Since the grade of PGMs in the catalysts is so low, approximately 0.5 wt. %, the present recycling technologies require high energy-consumption, it is of great significance to enrich the PGMs with some energy saving physical separation methods as a pretreatment. Automobile catalyst is usually composed of cordierite phase as a substrate and alumina phase, with PGMs, which covers the cordierite phase. We adopted the quenching pretreatment, one method of thermal shock, to generate micro-cracks between the two phases and separate the alumina phase from cordierite. Quenching was carried out by heating the catalysts in an electric furnace of different temperatures followed by rapid soaking into cold water. It was found that the phase boundary between alumina and cordierite was broken in the quenching and selective separation (detachment) of alumina from the cordierite could be achieved in the following surface grinding. The effect of quenching was checked by microscopic observation, hardness measurement, and chemical analysis. This paper figures out the stress formula of the quenching process, which is largely connected with layer thickness and temperature gradient by using an FEM (Finite Element Method) simulation and clarifies the mechanism of crack generation in the quenching process. Keywords: automobile catalyst, PGM, quenching process, FEM

Sep 1, 2012

By Tingting Li, Guodong Li, Dezhou Wei, Cong Han, Shuling Gao, Yanbai Shen

"The aim of this study is to solve the problem of tungsten leaching from scheelite concentrate using sodium hydroxide in the presence of phosphate by an autoclaving process, which is one of main development techniques for tungsten recovery. To understand the applicability and leaching performance of tungsten leaching from scheelite concentrate, the main work is to investigate the effects of leaching parameters such as initial concentrations of NaOH and Na3PO4, reaction temperature, stirring speed, liquid-to-solid ratio and reaction time on WO3 dissolution rate to obtain the optimal leaching conditions. The chemical composition and phase composition of the samples were evaluated by means of XRF and XRD. The content of WO3 in the leaching residue obtained via washing, filtering and drying was analyzed by thiocyanate spectrometric method. The optimal leaching conditions were found to be NaOH concentration of 6.76 mol·L-1, Na3PO4 concentration of 1.35 mol·L-1, reaction temperature of 180°C, stirring speed of 400 rpm, liquid-to-solid ratio of 2.0 and reaction time of 90 min. The results showed that tungsten leaching rate of 99.20% was reached under the optimal conditions. The technology exhibited superior leaching performance, which not only reduced the consumption of sodium hydroxide but also greatly decreased reaction time in comparison to a conventional autoclaving process. INTRODUCTION Tungsten is an important strategic metal, which is widely utilized in a variety of industries due to its high melting point, superior mechanical properties and heat-resistant performance [1-3]. The chief raw materials for the production of tungsten in nature are wolframite and scheelite [4, 5]. Among them, approximately two-thirds of the tungsten reserves contain scheelite deposits in the world [6, 7]. With the progressive exhaustion of high-quality wolframite resources, scheelite has become a predominant primary resource for the production of tungsten [8, 9]."

Jan 1, 2018

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 V. A. Chanturiya

The state-of-the-art of mineral mining and metallurgy industry in Russia is characterized by high demand of nonferrous, rare, rare earth metals, and highgrade coal, on the one hand, and by involvement of natural and technogenic minerals with low content of valuable components, fine (nearly emulsion) dissemination of valuable components and close physicochemical and process properties. This calls for high-productive and ecology-friendly technologies for more efficient mineral beneficiation based on intensification of operating and new methods to extract valuable components from rebellious ore and technogenic minerals, relying on the last achievements of basic sciences, combination of dressing and chemico-metallurgical processes and using advanced pyro- and hydrometallurgical technologies. The transition to a new strategy of processing is only possible based on the new technological–mineralogical appraisal of a mineral raw material. Actually, the process mineralogy has a stock of modern high-resolution physical methods for analyzing composition, structure and properties of geomaterials, inclusive of micro- and nano-levels: - Identification of micro- and nano-size noble metals, and natural and induced formations on mineral surface; - Experimental validation of structural phase and chemical transformation of minerals under different energy input; - Justification of choice and mechanism of interaction between flotation agents and noble metals with complex material constitution; - Analysis of structural, phase and chemical transformations of sulfides and rocks under leaching. Thus, process mineralogy is an informational background for a unified theoretical approach to scientific justification of flowsheets of efficient mineral processing. The article gives a brief review of practices that have found application and proved to be of high economic efficiency. Such practices are: X-ray radiometry and photometry separation (Uchalinsky and Gaisky Mining and Processing Integrated Works of ALROSA); selective disintegration (equipment engineered by Mekhanobr-Tekhnika and IPKON RAS); process selectivity enhancement (IPKON RAS, Central Research Institute for Geological Exploration of Nonferrous and Noble Metals, Chinakal Institute of Mining, Siberian Branch RAS, etc.); bacterial gold leaching (Olimpiada MPIW, technologies developed the Central Research Institute for Geological Exploration of Nonferrous and Noble Metals, Nezhdaninsky deposit projects, etc.); combination processing at a mining and metallurgy plant (Norilsk Mining and Metallurgical Company, Yaregsky deposit projects and others); processing of waste: overburden, mill tailings, slag, etc. (Kovdorsky MPIW, Svyatogor JSC, Ural Mining and Metallurgical Company, plants designed by the Central Research Institute for Geological Exploration of Nonferrous and Noble Metals, Mining Institute of Kola Science Center RAS, Research Institute for Chemical Technologies); water conditioning in mineral dressing circuits (ALROSA, equipment by IPKON, etc.); utilization of process water (ALROSA, Ural Mining and Metallurgical Company, Severalmaz JSC and others). Thus, Russia this time has the academic and engineering background for development of efficient energy-saving technologies for comprehensive advanced processing in accordance with the world’s standards, or even higher in terms of a number of the technologies, which has continually been highlighted by participants of recent international congresses on mineral processing.

Jan 1, 2018

By S. Gaydardzhiev

Laboratory batch tests having preliminary and orientation character aiming at improvement of the molybdenum flotation at Ellatzite copper processing plant in Bulgaria have been conducted. The following technological parameters have been screened to study their influence on the grade and recovery of copper and molybdenum during the rougher flotation stage: flotation pulp density, pH, addition of secondary collector and replacement of MIBC by pine oil as a frother. The results have shown that slightly better grade/recovery figures could be obtained for both copper and molybdenum at lower flotation pulp densities. The addition of kerosene has improved the recovery of molybdenum however, on the expense of that of copper. The effects from pH variation and the replacement of MIBC by pine oil as a frother have been almost negligible.

Sep 1, 2012

By P. S. Mukherjee

Mineral ilmenite is a major resource for titanium, whose major application is for production of Titanium dioxide (TiO2) for pigment application. The production of pigment grade TiO2 from ilmenite was earlier carried out by acid leaching, which has now been banned due to environmental regulations. Further acid leaching leads to loss of iron metal values as sulphate or chloride which are also treated as effluent. In thermal plasma processing the metal values are recovered as high value pig iron and Titanium dioxide is recovered as Titania rich slag containing 80 to 85 percent TiO2. The Titania rich slag has now been considered as a better input material than synthetic rutile for production of pigment grade Titanium dioxide. On the other hand, high value pig iron goes for automobile industry for specific application. An Inflight-flight Thermal Plasma Processing plant, used for the production of Titania Rich slag and high value Pig iron from ilmenite, with 20kg capacity was designed and fabricated. The reactor has the provision to utilize the flue gas generated for preheating the input of raw materials. Various aspects of designing the furnace operation include viz. Feeding the raw material at a fixed rate, designing the crucible used for melting ilmenite, proper cooling arrangements, an innovative method for tapping the melt, recovery of heat from the gases, various safety arrangements which are some of the important milestone of the present work. The various operations have been carried out through a controller panel. Experiments were carried out to optimize various processing parameters using statistical modeling. Large scale experiments have been carried out at 10 to15 kg scale. The material balance has been calculate, and it has been observed, that about 95 percent recovery could be obtained for both Iron and Titanium oxide from ilmenite. The detailed characterization on Titania rich slag and iron has been carried out. It has also been shown that using the above slag, it is possible to prepare nanosized Titanium dioxide powder containing about 98 percent Titanium dioxide by optimizing leaching conditions. Keywords: titania rich slag, ilmenite, thermal plasma

Sep 1, 2012

By H. Palza, C. Ihle, S. Contreras

"Processing of minerals, particularly treatment of tailings, has been increasingly challenged by the presence of clays in the feed of thickeners. This occurrence is expected to become increasingly important given the nature of ore deposits currently being exploited and those that have been recently discovered. In sedimentation operations (solid-liquid separation), industrial flocculants often fail to coagulate clay-containing fines, generating supernatants with high levels of turbidity, thus implying operational problems. Recently, it has been reported that graphene oxide (GO), a graphite derivative with high oxygen-containing groups, could enhance the flocculation of clay systems, due to the interaction between clays and GO functional groups. In the present work, we investigated the effect of doping industrial flocculants (commercial polyacrylamide) with GO on the floculation of kaolinite suspensions in a solid-liquid separation stage. Separation performance was evaluated by studying flocculation kinetics using a focused beam reflectance measurement (FBRM) instrument, in a set of batch tests. A statistical analysis of the flocculation kinetics and floc population distribution was further carried out. Our results suggest the existence of a synergistic effect between the studied flocculants and GO. This effect is observed as a decrease of clay fine contents in the supernatant, thus improving solid-liquid separation eficiency for high clay containing tailings. INTRODUCTION Copper, given its mechanical, physical and chemical characteristics, is a critical material for the progress of society and so has been from early stages of mankind. Demand for this metal has increased due to the growth of cities and the technological explosion, leading to increase current mining production and reinforce the efforts in exploration for new deposits (Elshkaki et al. 2016). As copper-rich deposits are being depleted, it has been necessary to develop proper technology to mine deposits of lower grades and more complex mineralogies, keeping in mind that the economic window that allows the exploitation of them is reduced by the increase on operating costs (Crowson 2012 and Northey et al. 2014). High clay bearing minerals are found in many of those low-grade copper deposits, and they induce problems in all stages of the mineral processing route (Taner and Onen 2016). Particularly, in the solid-liquid separation stage, the flocculation process fails to remove the clay fraction from suspension and it leads to operational issues such as filter damage, overconsumption of reagents and the need to add an extra clarifying step for the recovered process water. Those problematics pose an interesting challenge."

Jan 1, 2018

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 batch tests performed on different streams of the 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 particle recovery rate is significantly affected by mineralogical properties - in particular the degree of valuable mineral surface exposure.However, through the use of a nodal analysis technique developed by the authors, it can be concluded that particles with the same size and mineral composition do not all float with the same rate, but with a distribution of rates. The characteristics of this floatability distribution do not change during the flotation process. 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