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By T. B. M. Himawan

In this study, effect of thiosulphate and oxidation using oxygen were studied in arseno copper ore flotation. Single mineral study of chalcopyrite and tennantite in regard to the aforementioned techniques was also studied. Zeta potential, XPS, contact angle and floatability of single minerals were conducted for each treatment to understand the mechanism. It was revealed that the separation is best conducted in alkaline condition at where there will be interaction between thiosulphate and the mineral surface as well as the formation of hydroxide species in the oxidation using oxygen. From zeta potential of both thiosulphate and oxidation conditioning, it can be found that the reactivity of tennantite is much higher rather than chalcopyrite resulting higher rate of depression on both techniques as shown from contact angle and floatability of each mineral after treatment. XPS spectra confirmed qualitatively and quantitatively the existence of species responsible for the depression of each conditioning techniques. As for the copper ore flotation test, it is the oxidation using oxygen provides best performance after 60 minutes of oxidation. Keywords: tennantite, chalcopyrite, arseno copper ore A, thiosulphate, oxidation using oxygen

Sep 1, 2012

By Sepideh Javanshir

The process of liquid?liquid extraction of gold from chloride solution is complicated by the presence of many variables acting simultaneously in an unknown non-linear fashion for the determination of the final extraction efficiency. In practice, it is quite difficult to develop a model for predicting various properties of such process. Therefore, an alternative approach based on Artificial Neural Network (ANN) is considered to assist in the simulation process. Artificial neural networks (ANN) are powerful tools that can be used to model and investigate various highly complex and non-linear phenomena. This paper presents application of Multi-Layer Perceptions (MLP) to construct relationship that will be employed to develop a quantitative method for the estimation of the extraction efficiency as a function of hydrodynamical parameters such as stirrer speed, [AuCl4]- and DBC concentration, organic and aqueous flow rate. The model is shown to be in excellent agreement with the experimental data (R2 value for training and testing data was 0.9992 and 0.9915 respectively). Therefore, it can be used to optimize the parameters of liquid?liquid gold extraction with dibutyl carbitol (DBC).

Sep 1, 2012

By Kilian Neubert, Hermann Wotruba, Henning Knapp

Sensor-based sorting has been integrated into more and more applications in mineral processing over the past decades. Various sensor types, such as line scan cameras, near infrared sensors and X-ray transmission sensors, allow the separation of a vast variety of raw materials. Sensor-based sorting has several economic benefits which can make the difference between an uneconomic operation and a profitable mine. Sensor-based sorters can be applied to fulfill various sorting tasks, such as waste rejection, product quality improvement and ore type diversion, and have a significant impact on the layout of the processing plant. Therefore, it is important to include sensor-based sorting into the planning of a processing plant at an early stage. To evaluate the applicability of sensor-based sorting for any specific ore type, it is currently necessary to provide several hundred kilograms of material for subsequent bulk tests. In exploration, ore samples are usually rare and only available in form of drill cores. The acquisition of drill cores is time-consuming and expensive especially for deposits in great depth. Hence, it is unfavorable to spoil valuable drill cores for bulk tests. This paper describes a methodology to evaluate the applicability of sensor-based sorting based on drill core analysis. That methodology offers the possibility to calculate the achievable performances of different sensor types for various grain sizes without comminution of drill cores. The general methodology is shown on basis of an exemplary test work on drill cores from a currently conducted exploration.

Jan 1, 2014

By B. Orberger, J. M. Milazzo, S. B. Blancher, J. Lützenkirchen, J. L. Dubos

"Industrial dusts are commonly agglomerated using empirical recipes with binders such as bentonite, while Sludges are agglomerated into mixes. Those materials contaminate the products, are expensive and generate significant amounts of slag. Achieving cold dust agglomeration with little or no binder requires understanding the controlling parameters in order to predict and optimize the process behavior. This in turn necessitates comprehensive dust characterization to base predictions on measurable characteristics. In the present work we collected 13 Mn-rich dusts over all the process chain: feed fines, smelting, and refining dusts, as well as ferromanganese alloy dust. This is the first systematic study of dusts along the Mn-processing chain for chemical, physical and mineralogical parameters. X-Ray Diffraction, Qemscan® and laser granulometry analyses show that the mineralogy, Particle Size Distribution (PSD) and morphology evolves from complex heterogenous to simple, homogenous along the process chain: The mineralogy of the primary ore dusts shows various hydroxides, oxides, carbonates, tectosilicates and phyllosilicates. The furnace dusts contain oxides, tectosilicates and carbonates with volatiles, while the refining dusts present only oxides and metal. Finally, the Metal dust is nearly pure metal. Particle morphologies and PSD vary from jagged, irregular particles with broad PSD (>1 mm to <0.3 µm) to smooth and spherical with narrow PSD (100 µm to <0.3 µm). The Metal dust is an exception with angular particles. The Cationic Exchange Capacities (CECs) of all samples range from 0 to 22 meq/100g. Specific surface areas (SSAs) range from <0.1 to 27m²/g, and seem to decrease with from ore feed to Metal dust. This may be due to the disappearance of hydrated and/or sheet-bearing minerals, since a smaller grain size usually implies an increased SSA. The zeta potential varies strongly over the range of the samples tested. However, beside the Gabon ore which has an Isoelectric Point (IEP) ~ 4.1, the other IEP ranges between 2 and 2.5."

Jan 1, 2018

By I. Silin, H. Wotruba, J. Huben, A. Ognyanova

"With increasing shortage of raw materials, the beneficiation of ultra-fine ores will play a larger role in the near future. Many established process technologies do not yield satisfactory separation results for ultra-fine materials. Without selectivity, high-grade concentrates cannot be produced. The material at hand is a taconite which had to be ground to d(90) = 25 µm to guarantee liberation of the iron oxides. The comminution was done by High Pressure Grinding Roll (HPGR) and resulted in smooth surfaces and clear grain boundaries. This is an indication of selective grinding and mineral liberation. Further processing steps included selective desliming, magnetic separation as well as reverse flotation. INTRODUCTION During the last centuries, the processing of iron ores became increasingly important. The coarse-grained, so-called lump ores that are ready for direct usage in blast furnaces without further processing are becoming gradually less abundant. The processing of ultra-fine-grained ores, which in addition require a complex ore beneficiation due to the composition of the material, will progressively gain relevance with increasing resource shortages in the future (Arvidson, 2013). The term “ultra-fine” does not hold a precise definition in mineral processing. In this paper, “ultra-fine-grained” ores are defined by the required grind size for full liberation smaller than 20 µm. Many established mineral processing technologies do not yield satisfactory separation results for ultra-fine materials. Thus, they are limited in their application to produce high-grade concentrates suitable for sintering and pelletizing for direct reduction processes. The production of a high-grade iron concentrate (over 68% Fe) with low silica content (under 2.5% SiO2) is possible from both magnetite and hematite containing ore. In addition to the mineral processing technologies (magnetic and gravity separation, flotation), technologies for the liberation of fine-grained iron ores need to be developed and improved. In contrast to the conventional wet grinding circuit by means of tumbling mills, several future trends in dry and wet grinding and regrinding are already in use. These include technologies such as vibration mills (Palla®Mill), stirred media mills (Vertimill®), vertical roller mills (Loesche) and high-pressure grinding rolls (HPGR) (Jankovic, 2015). This study preliminary investigated the mineral processing of a low-grade, ultra-fine-grained, complex iron ore in a laboratory scale after dry grinding by HPGR to 90% < 25 µm without consideration of the grinding, milling, energy and classification cost."

Jan 1, 2018

By C. Perez

In mineral processing plants it is important to estimate rock composition, size and grindability to improve control of the grinding process. It is well known that variation in ore grindability and size distribution directly affects mills power consumption and throughput. This paper extends a general machine vision approach for on-line estimation of rock mixture composition using color information. Our proposed rock lithological recognition method requires the following steps: division of each image into sub-images, color feature extraction using the Binary Quaternion-Moment-Preserving thresholding technique (BQMP) and support vector machines (SVM) for classification. The BQMP thresholding technique splits the image in two and chooses representatives of each half using the histogram as features. The statistical parameters of the color data can be expressed using the quaternion moments into the representatives. This method can be recursively applied to the sub-images, obtaining 5x2n features in n iterations. Once the feature vector has been computed, each vector is assigned to one of three classes using a classifier. The method was tested on a database containing 20480 sub-images (64x43 pixels) of five ore types as follows: massive sulphide (MS), disseminated sulphide (DS), net textured (NT), gabbro (G), and peridotite (P). These ore types were assigned to three grindability classes: soft (MS), medium (DS and NT) and hard (G and P). The database was divided in 2 subsets: 15360 sub-images used for training and cross validation and 5120 sub-images used for test. The classification accuracy was compared with a method previously published based on a mixture of principal components analysis (PCA) for color, and wavelet texture analysis (WTA) for texture feature extraction. WTA-PCA approach reached a 76% accuracy in test while our BQMP method reached 90% of classification accuracy using only color features. Experimental results show that our proposed method yields excellent results compared to previously published results. Keywords: rock classification, lithological classification, grindability estimation

Sep 1, 2012

By P. Zarate, M. Peart, T. Bhambhani, D. R. Nagaraj

More than 50% of all the molybdenum produced in the world is a by-product of copper production. A bulk Cu-Mo concentrate is first produced, which is subsequently separated into Cu and Mo concentrates. The Cu-Mo separation circuits rely on the use of inorganic Cu sulfide depressants such as NaSH, Na2S, and Nokes, which are hazardous, and sometimes require very large dosages for effective depression. Synthetic polymeric depressants are safer and more efficient, and are now being used on the plant-scale. Data presented in this paper demonstrates that these polymeric depressants can replace 50-90% of all the NaSH in Cu-Mo separation at a fraction of the NaSH dosage. In this paper we provide an overview of the mechanistic and practical aspects of the Cu-Mo separation with inorganic depressants and polymeric depressants. Important practical aspects include depression dynamics (related to conditioning time and rate of depression), optimum pH for effective separation, the role of pH modifiers such as lime and NaOH, and the effect of flotation gas on the efficacy of the separation. Using nitrogen as flotation gas, the NaSH consumption can be reduced by up to 95% by using a small amount of polymeric depressant. The experiments with conditioning time demonstrate that there is a significant rate component to the depression mechanism with NaSH, which is absent for the polymeric depressant system. This has important implications in the effective use and application of the depressant. It is also demonstrated that the pH modifier type (NaOH or Ca(OH)2) has no significant effect on separation efficiency and Mo recovery (i.e. Ca2+ ions do not depress MoS2 in the Cu-Mo separation).

Jan 1, 2014

By Kazutoshi Haga, Batnasan Altansukh, Shirchinnamjil Nyamdelger, Atsushi Shibayama, Narankhuu Ariunbolor, Gunchin Burmaa

In this study, the authors investigated the capability of an acidic thiourea solution and silicon-organic polymers (PSTM-3c, PSTM-3T) as ion-exchange resins to recover of gold from gold-bearing ore concentrates. Firstly, elemental gold present in flotation concentrates was dissolved by leaching with a solution of nitric acid and thiourea under the optimized conditions. The best result on gold thiourea leaching was obtained under a nitric acid concentration of 2 N, thiourea concentration of 2 %, and oxidant (Fe2(SO4)3) concentration of 3 %, solid:liquid ratio (S:L) of 1:20, leaching time of 6 hours at 20 °C with a gold recovery of 93.7 % for a gold flotation (unroasted) concentrate. For the roasted gold concentrate, the dissolution of gold was 94.8% under the optimized leaching condition as nitric acid concentration of 0.5 N, thiourea concentration of 2 %, and the oxidant concentration of 1 %, S:L ratio of 1:10, leaching time of 4 hours at 50 °C. Secondly, a series of sorption tests was carried out on a pregnant leach solution containing gold complex Au[S=C(NH2)2]2+ using silicon-organic polymers (PSTM-3c and PSTM-3T), respectively. The effects of solution pH, adsorption time and temperature in the sorption process are also studied. As the results, the PSTM-3c and PSTM-3T polymers were adsorbed about 94.4 % and 95.1 % gold from the pregnant leach solutions under the optimum sorption conditions, respectively. It was found that the both PSTM-3c and PSTM-3T polymers were effective for the recovery of gold from the pregnant leach solution of thiourea. Adsorption activity of the PSTM-3c and PSTM-3T polymers was confirmed by new peaks near 1700 cm-1 in the FT-IR spectrum of the gold-adsorbed polymers, respectively.

Jan 1, 2014

By Chris A. Fleming

"The ability to recover cyanide from gold plant tailings has been known almost as long as the cyanidation process has been practiced, but there has been little incentive to process tailings in this way in the past. With the development of technologies that make it possible to recover and recycle free or complexed cyanide directly from gold plant slurry tailings, which indicates, on paper at least, significant cost savings compared to cyanide destruction, coupled with the introduction of legislation to seriously limit the discharge of cyanide to the environment in most gold-producing regions of the world, many companies are evaluating the cyanide-recovery alternative.There is arguably an even more compelling reason for mining companies to consider cyanide recycling. With the growing storm of negative public opinion that the use of cyanide in the mining industry is attracting - following several highly publicized spills over the last couple of years - the time has come for the gold industry to demonstrate environmental diligence and stewardship in the use of this commodity that is so vital for their industry. There is no doubt that the widespread implementation of cyanide recycling will reduce the impact of the cyanidation process on the environment, both by reducing the risk of spills (with less cyanide being transported from manufacturing plants to gold mines), and by reducing the loading of toxic and nontoxic metals and ions in the tailings.This paper briefly discusses the pros and cons of the different processes that are available for the treatment of gold plant tailings to regenerate and recovery cyanide for recycling, and presents a techno-economic argument for the incorporation of this technology into many gold plant flowsheets today."

Jan 1, 2003

By H. Z. Kuyumcu

Coking of coal blends using high volatile coals with poor coking abilities to produce a high quality coke for blast furnace application can be achieved by compacting the coal blend prior to the carbonization process. Here densification up to a relative material density of 80 %, i.e. a compact density around 1100 kg/m3, has proven to be advantageous. Coal is compacted by stamping, if the so-called stamp charging process applied. Compacting of the coal by pressing is practised in case of the cokemaking with so-called heat-recovery ovens. Stamped and pressed coal cakes require over the cake volume uniform high density and mechanical stability. Besides the aspects of the coal selection, the efficiency of the process is mainly determined by the operating parameters compacting time and compacting energy for coal cake making. At the Department for Mechanical Process Engineering & Solids Processing of the Technical University Berlin the two sub-processes of densification and strengthening during stamping and during pressing are theoretically and experimentally investigated using specially developed lab-scale compacting test units and a strength test device. Describing cake density in terms of coal properties for a given coal and measured compacting energy input then leads to a compacting equation with the so-called Stampability as the integral model parameter for the stamping process. For the pressing process the cake density can be calculated with the measured compacting pressure and the Compressibility factor, respectively. Investigations were carried out to provide evidence of a significant influence of coal type, coal surface moisture, coal granulometric and mechanical properties on the densification process. The overall objective of the work is to establish a comprehensive mathematical model on the compacting behavior of large coal bulk quantities and the optimization of the compacting processes by stamping and by pressing. Keywords: coal compacting, agglomeration, stamping, pressing, cokemaking

Sep 1, 2012

By David Dreisinger

"The leaching of base and precious metal ores and concentrates continues to progress in both laboratory study and industrial application. These developments are being driven by the need to respond to difficult ores and concentrates that are not amenable to conventional treatment. In many cases alternatives are being developed to conventional treatment (e.g. Pyrometallurgy) for technical and economic reasons.In this paper, a brief general review of some new developments in leaching will be followed by a more detailed explanation of three process developments that have either been industrially applied or are expected to be applied in a short time frame. The three processes to be reviewed in detail are the Mt. Gordon Copper Process, the Anglo American Corporation/University of British Columbia Copper Process and the PLATSOL Process. These leaching processes operate at low (90°C), medium (150°C) and high (220°C) temperature and are successful in quickly and completely extracting metal values from ores and concentrates."

Jan 1, 2003

By Peter Ay, Elena Geldt, Satyanarayana Narra, Claudia Glaser

"As part of an extensive research and development project, the technical and technological implementation of the patents DE 10 358 245 B4 and WO/2006/056172 was developed with the goal to present a system for the innovative roll- agglomeration method exhibiting a) a modular setup, b) high productivity and c) suitability for the use of fibres of different applications and product qualities (high technical availability). The processability of the rarely adapted raw fibre materials into high-value intermediates brings forward their application in various processing industries dealing with the production of fibre reinforced plastic composites, heat and sound insulation materials as well as with the gas and liquid cleaning systems. The innovative fibre agglomeration presented in this work is performed by a combination of rolling and pressing the fibres inside a geometrically pre-defined roller table, in which the fibres are forced to bound through entanglement / interlocking and develop into agglomerate. The agglomeration process is carried out in a circular roller path with a rectangular cross-section. For improving the adhesive properties, and thus the quality of the agglomerates, the boundary surfaces can be covered / patterned / lined / coated with various materials. The resulting roll-agglomerates are characterized by different quality parameters such as mass, shape, porosity and stability. The properties of the agglomerates can be modified based on the end-product requirements by slightly modifying the process parameters such as filling ratio, residence time, roll-geometry, procurement of the boundary surfaces, etc. as well as the input material properties such as fibre type, fibre fineness, fibre length, etc. This work carries extensive work on the roll-agglomeration system to assess the effectiveness and the variability based on the product specifications. Agglomerates were produced with wide variations of system parameters with varying roller table liners and based on evaluation of the produced agglomerates with respect to their mass, the geometrical dimensions, their porosity and stability."

Jan 1, 2014

By David Dreisinger

"The leaching of base and precious metal ores and concentrates continues to progress in both laboratory study and industrial application. These developments are being driven by the need to respond to difficult ores and concentrates that are not amenable to conventional treatment. In many cases alternatives are being developed to conventional treatment (e.g. Pyrometallurgy) for technical and economic reasons.In this paper, a brief general review of some new developments in leaching will be followed by a more detailed explanation of three process developments that have either been industrially applied or are expected to be applied in a short time frame. The three processes to be reviewed in detail are the Mt. Gordon Copper Process, the Anglo American Corporation/University of British Columbia Copper Process and the PLATSOL Process. These leaching processes operate at low (90°C), medium (150°C) and high (220°C) temperature and are successful in quickly and completely extracting metal values from ores and concentrates.INTRODUCTIONThe process of leaching is widely used in hydrometallurgy to selectively recover a metal of interest from an ore or a concentrate. Leaching and by extension hydrometallurgy is well established in the recovery of copper (copper heap leach ? SX-EW), nickel (Moa Bay and Caron process), zinc (roast ? leach ? electrowin and zinc pressure leach), gold (cyanidation) and uranium (acid sulfate leach). Of course this success extends to many of the metals found in nature. Recently, the importance of hydrometallurgy appears to be increasing with hydrometallurgy viewed as an attractive alternative to both traditional mineral processing and conventional smelting/converting/refining. This increasing interest has led to intensive study and increasing application. Selected developments include:Copper ? the Mt. Gordon process and new concentrate processes such as INTEC, Activox, CESL, Dynatec, Total Pressure Oxidation, MIM Albion, BioCop, and the AAC/UBC Process.Nickel ? Voisey Bay process for hydrometallurgical treatment of Voisey Bay concentrate, HPAL processing of laterites at Murrin Murrin, Bulong and Cawse, atmospheric leaching of laterites, heap bioleaching of nickel sulfides by Titan Resources (Australia).Zinc ? establishment of zinc leach, solvent extraction and electrowinning technology for treatment of the Skorpion deposit in Namibia, new developments in atmospheric and pressure leaching, the Hydrozinc process.Gold ? development of a number of thiosulfate leaching processes for recovery of gold from refractory carbonaceous ores or concentrates."

Jan 1, 2003

By J-P Franzidis, P. O. Gyebi

"Coal-water mixtures (CWM) of concentrated fine coal may be transported in pipelines but this is influenced by both CWM rheology and stability. Here, a low viscosity is required to reduce power requirements, as well as good stability for transport and storage. The objectives of this study are to investigate the importance of surface charge, solids concentration and dispersant addition on the rheology and stability of a fine Witbank coal-water mixture (<75 m). Zeta potential, rheology and stability were measured with a Malvern Zetasizer, a AR1500EA rheometer and a static rod penetration test, respectively. Sendep 30D, Sendep 30F and Norilose 8058, all supplied by Senmin International, were used as dispersants, at dosages of between 0.1 to 0.5% dry coal (w/w). Solids concentration was varied from 10 to 58% (w/w). The zeta potential was found to be positive at low pH and decreased sharply with increasing pH to a minimum of -50 mV at pH 10. The zeta potential decreased with increasing dispersant concentration for all dispersants. The lowest zeta potential of -63 mV was obtained for Norilose 8058 at a dosage of 0.3%. CWM rheology was Newtonian at lower solids concentrations but became non-Newtonian at solids concentrations over 40% (w/w), with an initial yield stress and pseudo plastic behavior. The yield stress decreased sharply with increasing dispersant concentration for all dispersants. The lowest yield stress was obtained for Norilose 8058. The addition of dispersants resulted in significant improvements in stability. A penetration ratio of over 70% was obtained for Norilose 8058 after 10 days. In summary, the addition of dispersants resulted in a decrease in the zeta potential which increased the electrostatic repulsive forces between particles, thus improving both CWM rheology and static stability.INTRODUCTION Coal Water Mixtures South Africa’s energy economy depends heavily on coal. It accounts for about 70% of primary energy consumption, 93% of electricity generation and 30% of liquid petroleum fuels (Eberhard, 2011). The transportation of coal to export markets and power generation stations is a problem in the South African coal industry due to ageing and inefficient rail infrastructure. This problem is intensified by the long distance of coal haulage, delays in the time required to load and unload wagons, and environmental challenges related to air pollution and water contamination. Fine coal may be transported more efficiently and economically in a pipeline as a highly concentrated coal water mixture (CWM). Typically a fine coal CWM will contain 60-75% coal, 25-40% water and nearly 1% of dispersing additives (Atesok et al., 2005; Dincer et al., 2003). However, the transport of CWMs in pipelines is strongly influenced by both CWM rheology and stability. Here, a low viscosity is required to reduce power requirements, as well as good stability for transport and storage. These quantities are affected by the coal composition/mineralogy, solids concentration, particle size and size distribution, particle shape, inter-particle forces and dispersant type and dosage (Laskowski, 2001)."

Jan 1, 2018

Traditional mineral processing techniques are more and more difficult to recover the increasingly low grade phosphate ores today. Although bioleaching method has been attempted to process low grade ores in hydrometallurgical field due to economical and environmental reason, it has been hardly used in leaching phosphate ore at home and abroad. Strains of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans were collected and separated from the acid drainage of a coal mine in Anhui province of China. Ultraviolet irradiation and Microwave inducement were applied to the bacterial cultivation process to produce strains of Acidithiobacillus thiooxidans and Acidithi-obacillus ferrooxidans able to tolerate extremely low pH conditions and generate sulphuric acid by oxidizing elemental sulfur or sulphide and the mutagenesis can achieve higher leaching rate. The bioleaching result will improve more by the addition of Tween series surfactants.

Jan 1, 2014

By M. Eraydin

Dewatering fine particles (e.g., flotation concentrates) is inefficient, energy intensive and often requires large capital and operating costs. To address these issues, a series of advanced dewatering technologies have been developed at Virginia Tech. These include novel dewatering aids and a hyperbaric centrifuge. Typically, the moistures obtained using these methods are 30% to 50% lower than those obtained using conventional methods, as demonstrated in laboratory and pilot-scale test programs. With another novel dewatering technology that has been tested in bench-scale tests, the moistures can be reduced to levels once believed to be attainable only through the use of thermal dryers. In this communication, test results obtained with these advanced dewatering technologies are presented and compared.

Jan 1, 2014

By G. Aguilera

The mineral suspensions do not present a newtonian behavior as their continuous phase; they can be pseudoplastic, dilatant, or both. The viscosity becomes as the most important rheological variable because the different industrial processes involve a wide variety of rheological scenes, with a specific rheological behavior for each one. Some authors have tried to model the viscosity of suspensions considering the volumetric fraction of solids and others have also kept in mind the size of the particles (Einstein, 1906; Batchelor, 1977; Jinescu, 1974; Krieger and Dougherty, 1959; Tangsathitkulchai and Austin, 1988). Others consider the shear rate (Cross, 1965; Hershel-Bulckley, 1926; Bingham, 1916, etc). However, none of the models is able to simulate the viscosity involving the physical, chemical and mechanic factors at the same time for crowded suspensions. A new model based on Neural Networks is presented, taking into account all the variables of ceramic clay suspensions and chemical additives. Keywords: viscosity, clay minerals, neural networks, simulation, mathematical function

Sep 1, 2012

By Kevin Galvin, James Dickinson

"The Reflux Flotation Cell (RFC) consists of an inverted fluidized bubbly bed, located above a system of parallel inclined channels. This novel arrangement enhances the hydrodynamics of flotation in a number of ways. Firstly, the free-surface of the flotation cell is enclosed via a fluidized bed distributor, ensuring uniform application of wash water to promote desliming. Secondly, foams can be variable in their stability and lack permeability. Hence this system is preferably operated in the absence of foam, instead opting for a bubbly zone of high bubble volume fraction through the use of a very high gas flux and/or wash water flux. Discharge of the product proceeds upwards through a central port of narrow cross-sectional area. Thirdly, the system of inclined channels increases the segregation between the bubbles and the water, ensuring the bubbly zone remains contained within the upper vertical zone, and the liquid flux reporting to the overflow is low. The expanded operating regime of the RFC was investigated by covering a very broad range of gas fluxes, up to 5.5 cm/s, and wash water fluxes, over 2 cm/s. Both laboratory and pilot plant performances were quantified by the recovery of hydrophobic particles and rejection of the hydrophilic particles, using model and industrial coal feeds. The new system hydrodynamics was found to offer significant advantages in flotation kinetics, desliming, and particle recovery across a broad particle size range. Bubble interfacial flux reached as high as 600 m2/m-2s-1. The upper system consists entirely of a high volume fraction of bubbles, which provides a "safety-net" to protect against the detachment of coarse particles, and a highly permeable zone for counter-current washing of the flotation product. Under relatively extreme conditions selective stripping of the product is observed, resulting in grade recovery values beyond those achievable using the tree flotation method."

Jan 1, 2014

By Fu Ping-Hao, Sergio Mauricio Vianna, Ewen Silvester, Emmy V. Manlapig

"Over the last 5 years, an ambitious project has been undertaken at the Julius Kruttschnitt Mineral Research Centre (JKMRC) aiming to isolate, study and, if possible, model the effect of particle size, liberation and collector adsorption density on the floatability of mineral particles. As part of this project, we have conducted highly controlled flotation test-work, combined with state-of-the-art solution and surface analytical techniques such as High Performance Liquid Chromatography (HPLC), Time of Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) and detailed mineralogical analysis to fully characterize the flotation behavior of a natural ore.The flotation tests were undertaken using a high-grade lead-zinc ore from BHP-Billiton’s Cannington mine (Australia) in a specially designed continuously operated laboratory scale flotation rig. Solution and adsorbed collector concentrations were measured independently during the course of the flotation tests using HPLC based ex-situ techniques. Liberation studies were performed using the JKMRC Mineral Liberation Analyser (MLA) on selected size intervals of different streams to estimate the specific surface area of galena. These results were used to calculate the collector adsorption density (collector coverage) on galena particles, with the eventual aim of developing a mathematical model describing the relationship between pulp chemistry, feed mineralogy, and floatability of galena particles."

Jan 1, 2003

By L. Burdukova

"In flotation, depressants are used to reduce the amount of gangue that reports to the concentrate and hence increase the selectivity of the flotation process. At the University of Cape Town extensive batch flotation tests are carried out to evaluate industrial depressants and standard procedures have been developed over the years.This study was conducted in order to develop an improved method for comparing depressants using machine vision as an aid. The modified method of batch flotation involved a test with prolonged intervals between scraping to allow more time for the froth to build up and mature.This method of testing showed increased differences between the flotation performance obtained as represented by grade recovery curves for carboxymethyl cellulose and guar depressants when compared to the standard method of testing with shorter scraping intervals. The improvement was attributed to reduced entrainment resulting from longer drainage time in the froth and therefore yielded a better test for comparing depressants on the basis of true gangue flotation with minimized entrainment. As expected, the sulphide recoveries were unaffected by the change in method. The machine vision system also added to the information obtained during these tests by recording bubble size trends throughout the tests which were later analyzed and related to the amount of flotable gangue in the froth. Modifications are recommended to improve the usefulness of machine vision in batch flotation."

Jan 1, 2003