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By Robert Peretti, Antonio Zucca, Andrea Manni, Silvia Serranti, Paolo Massacci, Marcello Ghiani

"This research study aims to identify the best way of processing colemanite concentrates, which is sometimes characterised by a high content of As sulphides, finely disseminated in the matrix of the boron mineral.Scanning Electron Microscopy analyses have been carried out to identify all the mineralogical constituents and to evaluate their distribution, frequency and mutual relationships.Colemanite concentrates are mainly used by chemical plants producing boric acid and gypsum. A high As content is unacceptable for further use of tailings coming from the leaching process and is very dangerous if the tailings are released into the environment.Grinding tests were conducted under dry and wet conditions in order to assess how As sulphide minerals are released from colemanite minerals.Some of the difficulties involved in obtaining selective liberation of As sulphides from colemanite minerals were overcome, although a certain decrease in As grade in the higher size classes was registered.All comminution products have been analysed by SEM, monitoring the degree of liberation of the mineralogical constituents.Flotation tests have been carried out, following different comminution flow sheets and adopting different modulating conditions in order to evaluate the influence of the following parameters:- collector concentration versus contaminants concentration (As minerals) in the froths;- kind and quantity of the frothing agent to maximise mineral recovery in the froths;- kind and quantity of the modulating agents to maximise the selectivity of the process;- conditioning modalities in order to obtain a suitable dispersion of fines and avoid segregation of Asbearing particles together with colemanite ones;- solid/liquid ratio of the pulp to minimise the water flow into the plant.Information obtained from SEM analysis has been adopted to evaluate segregation phenomena in pulp and in flotation products."

Jan 1, 2003

By J. Roth

The increasing demand of the filler industry regarding fineness and better delaminated products led to the development of a series of different grinding machines, which differentiate basically by the grinding mechanism as well as the kind of classification. Spiral jetmills grind, as it is well known preferably by delamination, therefore a spiral jetmill with integrated dynamic classifier has been developed. Especially the enhancement of the functional properties of the used industrial mineral fillers is a factor of highly increasing importance. These properties are very often bound to the platy shape of the minerals expressed by the aspect ratio. The developed Spiral Jetmill shows sufficient ability for such delamination and therefore increases in aspect ratio. In a series of comparative tests the suitability and advantages of this system regarding achievable fineness down to the submicron range as well as the conservation or even improvement of the aspect ratio of different minerals has been studied. As an emphasis on the results application tests with certain materials in the plastics field have been conducted. Due to the fact that in this range the required specific energy for achieving the necessary fineness increases exponentially another target is to optimize the grinding efficiency. A special feed control system provides on one hand a sufficient load inside the mill to obtain maximum utilization of the applied energy and on the other hand to prevent the mill from overfilling and coming with this a poor classification. The integrated classifier is a combination of a high speed motor with directly attached classifier wheels. This unit on one hand grants the necessary high circumferential speed of up to 190 m/s for providing an exact top cut of the ultrafine products and on the other hand gives the required operational reliability for continuous operation. Hard grindable impurities, which enrich inside the mill chamber, can be rejected from the process leading to an even cleaner product. Comparative tests on a talc product with certain free quartz impurities showed a significant improvement of the final product with respectively low loss on rejected material. This effect again had a beneficiary impact on the suitability of the final product when used in plastics application.

Jan 1, 2014

By John C. Gathje, Rick Moritz, Wilhelm de Beer

"Froth flotation has a long history of success for the recovery and concentration of a wide variety of minerals of commercial interest. Both the art and science of flotation have progressed greatly, and as our knowledge has increased so has our ability to improve mineral separations and recoveries.One area of interest in recent years has been the flotation of refractory gold ores to recover the gold-bearing sulfides. In many instances, the use of conventional air flotation to concentrate these values has achieved only limited success. However, as a result of intensive research, Newmont Mining has expanded the boundaries of flotation, and it can now be used to successfully treat many gold-bearing sulfide ores as well as platinum and palladium ores. This has been achieved through the use of the N2TEC technology, which utilizes nitrogen as an inert gas in the flotation process.Laboratory and pilot plant investigations and a commercial plant have proven its worth. Compared to air, the patented N2TEC process has increased the gold recoveries of many ores by 5 to 15 percentage points, and improvements of an even greater magnitude have been observed. This paper describes the process development for the flotation plant now being operated at Newmont’s Lone Tree Mine located in Nevada, as well as development work that was done on ores from their Twin Creeks Mine also located in Nevada."

Jan 1, 2003

By Seungwoo Park, Gaurav Soni, Roe-Hoan Yoon, Hyunsun Do, Kaiwu Huang

In a flotation froth (and foam), air bubbles become larger due to coalescence, causing bubble size to increase, bubble surface area to decrease, and hence casing less hydrophobic particles to drop off to the pulp phase below. Thus, bubble coarsening provides an important mechanism by which product grades are increased. On the other hand, excessive bubble coarsening results in low recoveries. In the present work, a model describing the process of bubbles becoming coarser in a foam as they rise to the top by deriving a mathematical relation between the Plateau border area, which controls film drainage rate, and the lamella film thickness, which controls bubble-coalescence rate. The model has been derived by assuming that liquid drainage rate increases due to slip at the air/water interface, and that the critical rupture thickness is determined by the capillary waves created by thermal motion. The model developed in the present work can predict the bubble size ratio between the top and bottom of a foam as functions of aeration rate, foam height, and surface tension (frother dosage). The model predictions are in good agreement with the changes in bubble sizes measured using a high-speed camera.

Jan 1, 2014

By S. A. Bogidaev, M. Yu. Tiunov

"The paper describes the results of the flotation tests with complex rare metal ores from deposits in the Trans-Baikal Territory. Correlations between the quality of produced wolframite, hubnerite and mica concentrates with or without the presence of various alkaline modifiers are determined. Commonly, rare metal ores contain minerals of comparable value to main elements recovered in processing plants using gravitational methods. The paper describes the results of flotation recovery of valuable minerals – main and associated – from gravity tailings of deposits in the Trans-Baikal Territory. It was found that gravity tailings from the first deposit contained fine-grained wolframite, mica (muscovite, lepidolite etc.), feldspar; hubnerite, scheelite, beryl, fluorite, rubidium-containing muscovite from the second deposit, correspondingly. This paper presents the results of the stage flotation tests with the production of tungsten (wolframite, hubnerite), fluorite and mica concentrates from gravity tailings. Figure 1 demonstrates the flowsheet of tungsten ore minerals and mica stage flotation from gravity tailings of the first deposit.Wolframite can be floated using oleic acid with the presence of soda ash, a complexing collector (IM-50), under slightly alkaline conditions in combination with a nonpolar collector [1, 2, 3, 4]. The study included wolframite flotation using the combination of two alkaline modifiers. Flotation of wolframite was performed after pulp desliming, using tall oil saponified with soda ash. The recovery of wolframite in the concentrate of rougher flotation reached 80-85%; the concentrate contained up to 1% of tungsten oxide that can be upgraded to a saleable product using gravitational methods. This procedure was tested during flotation of wolframite, tantalite-columbite and pyrochlore, and provided high performance regardless of a season, at pulp temperatures of 8-10°C, though fattyacid collectors are significantly inefficient at such low temperatures due to low solubility, dispersion and increased collector consumption, consequently. The introduction of two alkaline modifiers in pulp appears to improve these characteristics.The first stage of the tests was focused on increase of iron-bearing tungsten ore minerals recovery from gravity tailings and stabilization of the cold pulp flotation process."

Jan 1, 2018

By B. Mishra, Rahul Mohanty, Swati Mohanty, Swagatika Dash

Wet high intensity magnetic separators have been widely used in the mineral industry for separation of mineral particles based on magnetic properties. Usually, magnetic separators employ ordered array of grooved plates such as Lenoir and Jones plates onto which the magnetic particles get attached in the presence of a magnetic field. In the present work, we have carried out computational fluid dynamic (CFD) simulation, using Eulerian-Eulerian model to study the flow dynamics of magnetic and nonmagnetic particles within a matrix consisting of 2 mm size spheres of magnetic material, which are interconnected by wires, in the presence of a magnetic field. The three phases considered were the water, magnetic particles and non-magnetic particles. Model equations were developed considering each sphere in the matrix as a magnetic dipole, and the strength of the magnetic field at any point in the domain is due to all the dipoles. The size of the magnetic and nonmagnetic particles was 45 and 40 micron, respectively. The feed consisted of a slurry having 25 wt. % solids. The volume fraction of the magnetic particles was 0.04, and that of the non-magnetic particles was 0.045. The simulation was first carried out without the imposition of the magnetic field till a steady state was reached, and then the magnetic field was applied. The magnetic particles, as they flow down the matrix were attracted towards the region of maximum field gradient, which was in the central region of the matrix. A symmetrical pattern in the upper half as well as the lower half of the matrix was observed. As the particles moved downwards, the pattern changed, and near the outlet, most of the particles were found to flow out from the central part of the plane. This study can lead to a better design of a magnetic separator.

Jan 1, 2014

By Xing Yang, Zhen Peng, Guangwen Zhang, Haifeng Wang, Yaqun He

"Triboelectric separation of ilmenite ore based on the tribocharge differences between ilmenite and gangue minerals was conducted in this study. Triboelectric characteristics of ilmenite and its associated minerals were studied using polyvinyl chloride (PVC), pentatricopeptide repeats (PPR), copper, polymethyl methacrylate (PMMA), stainless steel (SS), teflon and quartz glass (QG) tribochargers in lab triboelectric unit. Results demonstrated that the ilmenite particles tribocharged positively while gangue minerals tribocharged negatively using PVC as tribocharger. The particle size also has a significant effect on tribocharge, and the -0.125+0.074 mm is the optimal size fraction of triboelectric separation. Charge-mass ratios of minerals increase with the increases of tribocharging length, but the increasing rate gradually reduce. At 1.5 m tribocharging length, charge-mass ratios of ilmenite, quartz, feldspar and mica are up to 6.07 nC/g, -6.05 nC/g, -4.30 nC/g and -4.56 nC/g, respectively. Based on the triboelectric characteristics of each mineral, triboelectric separation of ilmenite was conducted, and the grade of ilmenite ore increased from 15.47% to 28.40%. INTRODUCTION As a transition metal titanium plays an irreplaceable role in medical, aerospace and materials due to its light weight, high strength and corrosion resistance. Pure titanium dioxide is an excellent white pigment and is widely applied in industries of paint and textile. Ilmenite is the main raw material for titanium industry. For the beneficiation of ilmenite, series methods have been proposed, such as the application of dry magnetic and wet gravity separations to separate the ilmenite from the zircon and rutile. Electrostatic separation is extensively used in the beneficiation of heavy mineral sands for the recovery of rutile, zircon and ilmenite while flotation is used to separate fine ilmenite (Mehdilo et al., 2014; Fan et al., 2014). Compared with flotation and gravity separation, electrostatic separation does not consume water, and native properties of materials will not be changed and energy consumption will be reduced (Wang et al., 2014). Thus, the wide application of electrostatic separation and other dry separation methods is a trend in separation and purification industry, especially in water-scarce areas."

Jan 1, 2018

By M. R. Tavakoli Mohammadi

Novel solvent extraction technologies in recent decades have made attempts to show the problems in applying this method for dilute solutions and find appropriate solutions to overcome them. Improving the equipments performance used in this method for dilute solutions, cause development of usable resources and reduction of operational costs. Furthermore, appropriate conditions provide for using dilute solutions produced in various industries as a new source of valuable elements. Thus, this proposal can be a very good solution for treatment of these solutions and reduce the environmental impacts associated with them. The purpose of this study is to introduce a new method of Column Floto Extraction (CFE), which has been invented in this regard. In this method, using spargers similar to Jameson cell downcomer in floatation process, the organic phase bubble dispersion has been used instead of its drop dispersion in aqueous phase for the two-phase mixture operation. This operation mode has caused a higher extraction percentage of solute in high aqueous to organic ratios due to enhancement of contact area. In this study, in addition to explaining the advantages and features of this method, we have dealt with its design and performance mode.

Sep 1, 2012

By Ashish Agarwal

For a correct evaluation of the performance of any process, it is important to reconcile the data gathered in the plant from the material balance point of view for all the streams flowing in and flowing out of the process unit. There are two main approaches to reconciliation of data, which involve minimization of the sum of the squares of: (i) the closure residuals and (ii) the component adjustments; both weighed with the estimated variances of the components. Though, these approaches have served us well, it has not been possible to ascertain if the reconciled values for various components and the split factors obtained using these approaches are truly the best estimates. In this paper, this aspect has been investigated by analyzing pseudo-experimental data of known error structure on size classification of particles in a hydrocyclone. Three types of basic error structures were considered for the measured component values: absolute error, relative error and chi-square error. The error structure was modified by adding a random component of error using normally distributed random numbers corresponding to zero mean and different levels of variance. By carrying out a large number of simulation experiments, it has been shown that in the presence of random errors, irrespective of the basic error structure of data, which is usually unknown, the chi-square error minimization criterion can be used to obtain most reliable results. Keywords: data reconciliation methods, chi-square error minimization

Sep 1, 2012

By I. Gombköto

Mining and mineral processing operations are usually generating huge amount of tailings. These tailings often gives lots of maintenance work in order to protect environmental resources from heavy metals slowly leaching out of tailing are due to Acid Rock Drainage (ARD) process. Handling leakage could be active or passive such as using of Permeable Reactive Barriers (PRB). PRB?s are used worldwide treating underground contaminations, using different type of matrix materials. All generally used matrix material has its advantages and disadvantages such as selectivity, sensitivity of precipitation generation or not satisfying hydraulic conductivity. Nowadays cheap and effective matrix material which is ignorant to pore plugging caused by precipitation within the PRB could be one solution to the demands of the industry. The authors have been carried out an investigation at University of Miskolc on lignite as high humid acid containing material for determining the ability of heavy metal adsorption and pore plugging resistance. Moreover, using hydraulic and chemical simulation methods, complete PRB dimensioning protocol based on new lignite matrix had been introduced. Within the frame of this paper the results are going to be discussed.

Sep 1, 2012

By D. Hatfield, G. de Jager

"The rapid developments in computer vision and computational resources are creating new possibilities for the use of machine vision systems for industrial control. A number of commercial image analysis systems exist, and research into improved measurements of froth performance is ongoing. An integral part of the implementation of these systems is the validation of the relationship between image analysis measurements and flotation cell performance. This paper discusses the factors affecting concentrate flow and presents the results obtained from one such system with respect to its ability to estimate the flow of concentrate from a flotation cell.The relationship between froth flow speed and the rate of recovery of concentrate from a flotation cell was investigated on two industrial operations, both processing PGM (Platinum Group Metal) bearing ores. Results are presented that show a relationship between froth flow speed and concentrate yield."

Jan 1, 2003

By I. Yu. Rasskazov, A. V. Rasskazova, N. M. Litvinova, N. A. Lavrik, V. G. Kryukov

The possibility of the intensification of the gravity processing of complex iron-manganese ore, which contains the finely dispersed inclusions of gold and platinum is shown. Clear mineral fractions of precious metals were sorted out of the different types of ores (quartz-braunite and carbonate- magnetite ore, ferruginous quartzite, carbon-containing shale, breccia-limestone and dolomite breccia). Composition and structures of precious-metals particles was detailed. The industrial content of platinum and gold was found. Precious-metals mineralization is character for all types of ores. High content of platinum is indicated in the carbonate-magnetite (up to 11.3 mg/kg) and quartz –braunite (up to 10 mg/kg) types of ore. Gold is presented in the ferruginous quartzite (up to 1.29 mg/kg) according to the data of the reduced mineralogical analysis. The composition of native platinum depends on the type of the ores: 1) quartz-braunite type contains isoferroplatinum (Pt3Fe) with Cu, Rh, Ir, Ru; 2) carbonate-magnetite type contains isoferroplatinum with Cu, Sn, Ni, Rh, Ir, Os; 3) pyritic-carbon ore contains isoferroplatinum with Sn, Ni; 4) ferruginous quartzite contains isoferroplatinum without admixtures. The ultrasonic treatment of mineral aggregates (P = 41.5 Watt, I = 15 W/cm2) made possible the liberation of fine particles of precious metals. Smooth-shaped or crystalline mineral aggregates are effectively liberated after acoustic treatment. Their surface is freed from impurities. The aggregates with the complex form and structure, which consist of the numerous plates and the grains, are not effectively liberated from impurities. It is shown that the ultrasonic treatment of aggregates with the fine inclusions of precious metals contributes to the liberation of the particles of platinum and gold and intensification of the gravity processing of refractory ore. This approach contributes the increase of the raw-material base of precious metals.

Jan 1, 2018

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 A. Otsuki

This paper describes the evaluation method of dispersion and coagulation of silica nano-particles by means of interactive force apparatus. The apparatus measures the size of fine particles in aqueous solution or organic solvent of high concentration and/or low optical transparency. Other conventional apparatus for size measurements (such as, apparatus utilizing dynamic light scattering) are difficult to measure the size of particles in such conditions accurately, due to multi-scattering of light in the sample solution or solvent. The apparatus measures the interactive force between two surfaces, i.e. the gold-coated glass hemisphere and the brass flat plate, (which is fixed at the bottom of the sample cell). The apparatus has three parts, i.e. main part (which consists of electric balance, hemisphere and flat plate), control part (i.e. personal computer, piezo-stage controller and voltage supplier), and detecting part (i.e. multi-meter and oscilloscope). During the measurement, electric field is applied between the hemisphere and flat plate, and thus dielectric particles are arranged toward the direction of electric field in the area between two plates. When the two plates are close to each other, two different forces (i.e. repulsive force and attractive force) will alternately act on particles due to the structure change of the particles. The repulsive force occurs when the structure of particles is stretched by compressive force; whereas the attractive force occurs when the aggregate structure is broken. The cycle of the repulsive and attractive forces is a primary size of particle or size of aggregate, which depends on the degree of agglomeration. The measured size of particles, which is varied depending on their degree of dispersion and coagulation, determined the characteristics of the silica particles. In this research work, the effect of size and concentration of particles in aqueous solution on the degree of dispersion and coagulation of the silica particles were investigated. Spherical silica particles were selected for this investigation due to their variety of size. This apparatus can be used to evaluate the degree of dispersion and coagulation of other nano-particles in various solvents in many process industries.

Jan 1, 2014

By Brian Hart, Liuyin Xia, Staman Dimov

The recovery of rare earth elements (REE) is fast becoming of significant interest globally. Modern research and development programs (outside China) towards the optimization of REE mineral recovery by flotation have been lacking. Due to the mineralogical nature of many hosting deposits, the separation and recovery flotation flowsheets can be very complex. As part of a research project, a selected suite of hydroxamic acid collectors (Naphthoyl, Cyclohexyl, Benzoyl, Octyl, Terta-butyl benzoyl, Salicylic) were tested in order to examine their potential for recovery and selectivity. Micro flotation tests were conducted on a feed sample, recovery and grade of the products were used to evaluate their relative flotation efficiency and selectivity and these results (flotation with the hydroxamate collectors) were compared to a phosphoric acid/sulphonate collector mix(shorten as "mixed"). In the testing, the flotation response with the hydroxamate collectors was significantly better than the "mixed" collectors on freshly ground (no slimes removed) samples. Furthermore the tests revealed that for most of the hydroxamate reagents tested, their dosage requirements to achieve recoveries at the same levels was less than that for the "mixed" reagents. Product assays show that recovery of both La and Ce is significantly better for using the salicylic hydroxamate and that Nb, Y and Zr recovery are favored by using octyl hydroxamate. These results indicate mineral flotation selectivity could be achieved by using selective hydroxamtes. Spectral fingerprinting by TOF-SIMS surface analysis has allowed for the identification of reagent species. TOF-SIMS surface analyses of grains analysis confirmed that REE bearing grains reporting to the concentrates are doing so in response to collector attachment whereas grains reporting to the tails are doing so in response to a lack of collector. The TOF-SIMS surface data bas been used to examine the factors promoting flotation stream partitioning.

Jan 1, 2014

By Gabriela Pino, Maurício Torem, Diego Veneu

Because of its simplicity, economy and biocompatibility, research regarding the use of microorganism for decontaminating heavy metals produced by many industries is an area of growing interest. Also, there is a stringent need for the control of toxic metals produced during various production processes and released into the aqueous environment in order to avoid damage relevant to soil or groundwater contamination. Among the available treatment technologies, sorptive flotation has been considered as a promising alternative for the wastewater treatment. In the present study Streptomyces lunalinharesii strain was applied as bioreagent for the removal of copper, cadmium and zinc. The removal of those metal ions depends mainly on the respective pH value, influencing the aquatic speciation during the process, as well as the zeta potential of the system and biomass concentration. Langmuir and Freundlich isotherms have been depicted. Dispersed air flotation was applied as the subsequent separation method for harvesting the suspended metal laden microorganisms, following the biosorption of copper, zinc and cadmium. The investigated parameters (in batch mode, laboratory scale) were in this case the saturator pressure, the coagulant concentration and the recycled flow. Applying the optimum defined conditions, over 60% removal of metal ions have been achieved in one stage and simultaneously, quantitative separation of the used (metal-loaded) biomass has been obtained.

Jan 1, 2014

By Kaiwen Liu

Activated carbon is widely used in the removal of organic and/or inorganic contaminants from waste water due to its high surface area, porous structure, and specific surface reactivity. However, in practical applications, it is difficult to recover the activated carbon completely by screening or classification. In this project,we prepared a magnetic form of activated carbon (magnetic activated carbon or M-AC) by precipitation of iron oxides on the surface of activated carbon. The M-AC can be easily separated from effluents by applying an external magnetic field, thus it can be recycled and regenerated for reuse. M-AC was characterized by X-ray diffraction (XRD), specific surface area measurement, and scanning electron microscope (SEM).XRD results show that the major phase of coated iron oxides on activated carbon is magnetite (Fe3O4). The specific surface area of activated carbon was found to be reduced after the impregnation of magnetite particles on the surface. The SEM micrograph shows the aggregation of the iron oxides on the surface of activated carbon. M-ACwas found effective in removing DETA (diethylenetriamine) species and metal ions from solutions. Cu (II) with initial concentrations from 5 ppm to25 ppm in solution is removed by more than 99% with the addition of 0.1 wt.%ofM-AC. For the removal of 25 ppm DETA species from solution, an addition of 0.5 wt.% of M-AC is required due to the larger size of the DETA molecule. Moreover, M-AC showed a good loadingproperty for nickel and gold ions from solutions. M-ACshows a better adsorption capacityover activated carbon and its potential applications in carbon-in-pulp for gold leaching and waste water treatment. Keywords: magnetic activated carbon (M-AC),diethylenetriamine (DETA),metal ion,adsorption

Sep 1, 2012

By Paul Gottlieb

This paper reviews the status of automated applied mineralogy today and describes the history and fundamental theoretical and practical bases underpinning the development of automated systems. Details are given of the technical challenges that were faced in creating the new technology and in applying it to a range of applications. In recent years, automated mineralogy has become established as an essential enabling technology for the reliable acquisition of statistically sound comprehensive mineralogical and metallurgical data. This has had a revolutionary effect on the industrial use of such data in the study of geology, mining and mineral processing. Previously, using manual methods, it was not feasible to attempt this work because the large data sets required could not be assembled in a realistic timescale. There was a reliance on individual expert mineralogists and this was not scalable. The speed, reliability, detail and repeatability of the modern automated measurements has now made this type of analysis routine. Automated Applied Mineralogy has come of age! More than 100 systems have been installed around the World. Automated mineralogical analysers such as QEMSCAN® were originally developed as diagnostic metallurgical tools to improve mineral processing plants using samples drawn from plant surveys, bench and pilot-scale tests. They were used mainly for the assessment and auditing of size fractions of mill products, such as concentrates and tails. Subsequently, they began to be used for concentrator design and optimisation where ore characterisation was used to help understand the relationship between the feed ore and its subsequent behaviour in the plant. They are now widely used to measure exploration cores and drill chips from drilling programs to predict eventual metallurgical performance. Ore samples can be classified into metallurgical, as well as geological types, by combining mineralogical features in the ores with metallurgical properties related to grade control, separation, comminution, flotation and leaching behaviour. Three-dimensional block models of ore deposits are now being created based on processing response in addition to geological and mining properties. The development of automated systems began in Australia, the United Kingdom and Canada in the late 1970s and early 1980s. There were many technical challenges. Mathematical theories of randomness, sampling theory, image analysis and stereology were developed to ensure sample representivity so that meaningful information could be obtained. Sample preparation, presentation and measurement methods were developed to ensure that the random sampling was preserved during the measurements. Methods of automatic measurement and mineral identification evolved from the use of electron microscopes, fitted with backscattered electron brightness and energy dispersive X-ray detectors. Operational procedures were required to ensure that these instruments could accommodate a large number of samples and operate unattended for long periods of time. The new technology was progressively applied to a range of commodities and applications and new analysis methods, such as liberation measurement, were needed for metallurgical interpretation of mineralogical data.

Jan 1, 2014

By C. H. Veloso

"Starch is the most widely used depressant in the reverse cationic flotation of iron ores. There is however, an indication from recent studies, that other polysaccharides may successfully replace them. When starches are used in the flotation of iron ores in the presence of quartz as gangue mineral, their strong adsorption on the surface of iron oxides can be explained by the molecular conformation between the available sites on the mineral surface and two hydroxyls of starches. However, when the gangue minerals are iron-bearing silicates, the strong interaction with starch can occur on these minerals since they have the same surface behaviour as iron oxide. In this work bench scale tests were conducted in order to generate scientific knowledge about other alternatives depressants for the flotation of iron ores. A magnetic pre-concentrate from a skarn iron ore processing plant was used as feed material for flotation tests. The reverse flotation approach was used to upgrade the iron content by removing complex ironbearing silicates. The depressants used in this study were: corn starch, dextrin, carboxymethyl cellulose (CMC) and humic acid. The tests were performed under different pH conditions in order to try to relate the efficiency of depression to the pH used during flotation. The results show the important role of pH as each depressant reached its best performance at different pH values. At alkaline pH the corn starch showed best depression performance while the humic acid is more efficient at pH close to neutrality.INTRODUCTIONIron corresponds to approximately 6% of earth’s crust composition (McDonough and Sun, 1995). It is the most used metal in our lives, some of its properties as resistance and facility to be shaped makes is replacement very difficult. The primary sources of iron on our planet are minerals. The iron-bearing minerals most commonly found in nature and economically exploited are magnetite [Fe3O4], hematite [Fe2O3], goethite [FeO(OH)] and siderite [FeCO3] (L O Filippov et al., 2014). These minerals are commonly associated with other minerals (most of the time not economically exploited) forming the so-called iron ore. Iron ore is the source of primary iron for the world’s iron and steel industries."

Jan 1, 2018

By M. S. Eygi

This study covers the investigations based on the electrokinetic and rheological properties to explain the interactions between kaolin minerals and commercially available polyelectrolyte in anionic character. Additional adsorption test were also conducted to support the interaction mechanism. Adsorption tests showed that adsorption densities decrease by increasing the solid content. In-creasing the solids contents from 1% to 30% by weight resulted in the decrease on adsorption from 2.14 mg/g to 1.85 mg/g. Because of its difficulty, the solids ratio at 70% was not studied. However, following to trend of the curve plotted adsorption density-solid ratio, an estimation was made and adsorption density at 70% solid content was extracted from the curve as 1.75~1.80 mg/g. The electrokinetic studies pointed out that the presence of polyelectrolyte increase the zeta potential of kaolin from 40 mV to 60 mV which is reasonable conditions to disperse and stabilize the kaolin slurry and lower the viscosity. When these result of the different tests are combined and considered together, 2 mg/g polyelectrolyte concentration was noted as optimal concentration where adsorption density, viscosity and zeta potential of the slurries give maxima and remain constant after this concentration.

Jan 1, 2014