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By Narasimha Mangadoddy

The complex nature of multi-phase flow in dense medium cyclones has restricted plant operators and designers to rely on empirical equations for predicting the performance. A number of empirical cyclone models have been developed in the past (Wood, 1990; Dunglison, 2002). In recent years, this subject has been broached with computational fluid dynamics (CFD). Most of the CFD models have not considered the correct rheological behavior of magnetite medium while simulating the medium segregation inside the cyclone. These models mostly predict excessive underflow volumetric flow rates. In this paper simulations of magnetite medium in a dense medium cyclone, were conducted in FLUENT where the particle phases were simulated using the modified Mixture model. The turbulence was resolved using Large Eddy Simulation (LES) model. The rheological behavior of medium was considered in the form of Granular viscosity, Newtonian and Non-Newtonian models corrected with particle loadings and fraction of ultrafines. Multi-phase simulations using granular viscosity option although predict the overall split product medium densities reasonably close to experiments, the mixture viscosity values are restricted to substantially lower values, similar to water viscosity. Simulations using Newtonian viscosity model corrected with particle loading, and fine fraction below 53µm size is predicting overall mixture viscosity levels well over water viscosity levels, but under predicting the under flow the underflow medium density. Multi-phase simulations using Non-Newtonian Herschel-Buckley model, calibrated for superfine magnetite medium measured viscosities, is closely predicting the medium segregation with gamma ray tomography data. Overall predicted product medium densities, underflow volume split are close to the experimental data. This model is can be further used to simulate coal portioning and hence in developing new designs.

Sep 1, 2012

By W. G. Wu

More and more researches and applications of organic chelating agents as depressors or activators are carried out in the course of research and application of modern flotation. The paper puts forward the necessary condition of organic chelating agents as depressors or activators by analyzing the chelating chemical performance of organic chelating agents with metal ions and the stability of chelates formed by them; at the same time, puts forward four sufficient conditions of organic chelating agents as depressors or activators according to different hydrophilic capability of the chelates and different performance of depression and activation of organic chelating agents for minerals. Namely, the ?1+1/4? necessary and sufficient conditions of organic chelating agents as depressors or activators are put forward.

Jan 1, 2014

By P. Latostenmaa, T. Hailemariam, M. Lundström, P. Halli

Doré process is unique way to treat precious metals in the copper electrorefining plant, since it uses anode slime as a raw material. In this pyrometallurgical process, also slag is produced together with Doré metal. However, the process is never ideal, and a part of metal is always lost into the slag. By using Doré slag as raw material for simply mineral acid leaching, some of the lost elements can be extracted and recovered, thus, increasing the sustainability and keeping metals in the circular economy loop. The Doré process itself is developed to convert almost all precious metals and PGMs in the Doré metal, leaving other elements into the slag fraction. The Doré slag consist of slag formers, such as borax and silica based minerals, but contain also traces of sealing materials. In addition, the Doré slag is rich in metals present in the anode slime, such as Cu, Bi and Sb, which are not converted into the Doré metal. There are only few published applications at the precious metal plants, where conservative grinding and flotation circuits have been utilized for the enrichment of valuable metals present in the Doré slag fraction (Godbehere, P.W., 1983; Segawa, C. and Kusakabe, T., 1996). However, the present study shows an alternative approach for the recovery of metals present in the Doré slag by hydometallurgical approach. The study focus on direct mineral acid (aqua regia) leaching of metals present in the Doré slag. The initial dissolved concentrations of Cu, Bi and Sb from Doré slag in the temperature range of 30-50 °C under oxygen purging with addition of 1 vol-% of H2O2 are presented. Chemical and mineralogical analyses were performed for the raw material, leaching residue, and leaching solutions in order to ascertain the leaching behavior of the metals of Bi, Cu and Sb.

Jan 1, 2018

By J. C. Wilmot

The chemistry of aqueous cyanide containing species in the presence of reduced sulfur sources was investigated. Reactions were studied as a function of time and tracked using novel analytical techniques developed for the analysis of the species of interest in the sample matrix. Species of interest in this work were ?free? cyanide, thiocyanate, cyanate, metallo-complexed cyanide, and various sulfur and sulfur-oxygen species. The studies were conducted under constant temperature conditions at pH values above 10.5 and in the absence of light in order to eliminate photochemically induced cyanide reaction effects. The reaction products of cyanide when in contact with pure sulfur, pyrite, pyrrhotite, sphalerite, and cinnabar are reported. These data combined with data for cop-per, arsenic and lead sulfides, which have been previously published, are used to predict the fate of cyanides in refractory gold ores containing sulfides. A mass balance on the cyanide reaction products was completed for all experiments. From these studies insight into the chemical relationships of cyanide, the specific metal sulfide, thiocyanate and cyanate have been gained. When looking at the results of the experiments, it was immediately apparent that even though the overall conversions of cyanide to thiocyanate were different, most of the samples exhibited a similar pattern of reactions. The recovery of cyanide in these experiments was better than we expected, averaging in most experiments to be over 90 percent. Based on this research, the formation of cyanate was probably the main route of loss. The pathway choice for the various minerals was also elucidated in these experiments. The competitive oxidation pathways that cyanide can take have been tracked for sufficient time to determine the ?final? fate of cyanide in a process. Initially, it was thought that the cyanate may be involved in a hydrolysis reaction to form ammo-nia and carbonate ion, but upon further inspection of the data, there was not the drop-off in total cyanide recovery that would manifest itself were this to happen. On the other hand, the hydrolysis of thiocyanate to cyanate and sulfate would require oxidizing conditions which did not exist in solution at the beginning of the experiment. If the solutions were to be sufficiently oxidizing in nature for this to happen, the initial amount of cyanide would have been converted to cyanate quickly. The data support premise that the ?hydrolysis? of thiocyanate to cyanate and sulfate occurs to some extent in the experiments conducted. Knowledge gained from the experiments with pure metal sulfides helped interpret the results of experiments with refractory ores found in the State of Nevada.

Jan 1, 2014

By Ljubisa Obradovic, Baisui Han, Batnasan Altansukh, Zoran Stevanovic, Atsushi Shibayama, Jonovic Radojka, Daizo Ishiyama, Kazutoshi Hag, Radmila Markovic, Ljiljana Avramovic

This paper discussed a combined froth flotation and high pressure leaching (HPL) process to recover copper from mine tailings. At first, froth flotation were carried out using the mine tailings sample under various conditions in the presence of different pH (3.5-10) and sulfurizing reagent value (0-1000 g/t), respectively. As a result, optimum condition (sulfurizing reagent of 1000 g/t, pH of 10, PAX (collector) of 100 g/t and MIBC (frother) of 200 g/t) was found for froth flotation of copper. The effects of sulphuric acid concentration, leaching temperature, total pressure (steam pressure plus oxygen pressure) on high pressure leaching (HPL) of mine tailing were investigated using sulphuric acid solution in the presence of oxygen. The best conditions for HPL were obtained to be sulphuric acid concentration: 0 mol/L (water), leaching temperature: 170 ?, total pressure: 2 MPa, leaching time: 1 hr and pulp density: 100 g/L. The leaching rate of copper reached nearly 99 % and the concentration of copper in pregnant leach solution (PLS) was 0.24 g/L. Finally, copper in the mine tailing was recovered using froth flotation followed by HPL. As a result of a combined froth flotation and HPL, the vast majority of copper (99 %) from the mine tailings was extracted.

Jan 1, 2014

By S. Safak

Europe retains a modest position in world mining activity in terms of scale of production and mineral reserves but maintains a non-negligible role in the world mining industry. The concept of sustainable development resting on three pillars of economics, environment and social development has become an increasingly important factor in the European mining sector and a major influence on the related policies of the European Commission. Members of European mining industry shall conduct their activities according to the principles which promote sustainable development. A successful minerals planning policy should create the legal administrative environment that is necessary to ensure the sustainable supply of minerals to society within the framework of sustainable development. Members of the European mining industry shall conduct their activities according to principles which promote sustainable development. The challenge for sustainability is to find a balance between securing minerals supply, protecting the environment and achieving social progress. The point of balance depends on the range of policies adopted by governments. In this paper the development of the sustainability of the mining sector in EU and the social component of sustainability in the mineral industry is discussed.

Jan 1, 2014

By Saveliy F. Kaplan, Valeriy N. Tsyplakov, Vasily N. Kovalev, Igor A. Agapov, Nikolai V. Vorob’ev-Desyatovskii

"Based on the experiments, a possibility of successful processing of double-refractory gold sulphide concentrates with a high content of natural organic carbon, which has a high sorption capacity toward gold chloride complexes, has been demonstrated. The proposed approach involves deep burnout of sorption-active organic carbon in an autoclave at a higher temperature and a longer retention time. INTRODUCTION It is known that one of the reasons why gold-bearing ores and concentrates are refractory is the occurrence of fine gold in sulphides (usually in pyrite and arsenopyrite) in ores and concentrates. In addition, refractory gold-bearing ores and concentrates also contain an organic carbonaceous material, which has a sorption capacity towards gold chloride complex, making the ore or concentrate even more refractory. In pressure oxidation, metallic gold is oxidized by Fe (III) aqua-ions and complex Au(Cl)4- ions are formed at temperatures over 180°C, in the presence of chlorides contained in ores. Complex gold anion is adsorbed on the organic carbon surface and then reduced to Au0; the chloride ion is regenerated and gold, adsorbed on organic carbon microparticles, is ultimately transferred to tailings (preg-robbing). Currently, there are several suggestions how to suppress preg-robbing (Simmons, 1998, Pyke, 1999, Rees, van Deventer, 2000, Zhao Jun-wei, 2008). It can be done by reducing the organic carbon content by processing (flotation, etc.),reducing chloride ion concentration by preliminary washing of concentrates in thickeners, reducing the adsorption capacity of organic carbonaceous material by introducing some organic substances that are strongly adsorbed on its surface (blanking agents), and reducing the redox potential of the slurry liquids by introducing neutralizing agents (limestone)."

Jan 1, 2018

By F. Bello, J. Engels

"During 2012 and 2013, Minera Esperanza conducted a series of thickening and deposition trials to identify design and operational parameters associated with increased thickening of its tailings. These trials focused on benchmarking the current solids concentration of tailings (62 - 64%) in anticipation of an increase to 67% solids once two new 45 m diameter deep-cone paste thickeners are commissioned in 2014. These trials studied the sedimentation and rheological characteristics of the existing tailings and performed deposition modelling to assist with developing short- and long-term designs for the tailings storage facility. To verify and optimise these models, Minera Esperanza considered a series of laboratory, pilot, and industrial-scale deposition trials. This paper provides a review of the trials conducted in the laboratory and at industrial-scale and considers the results and optimisations for the short- and long-term design of Minera Esperanza’s tailings storage facility."

Jan 1, 2014

By Magnus Evertsson, Haijie Li, Erik Hulthen, Mats Lindqvist

"The static and dynamic models for autogenous (AG) and semi-autogenous (SAG) mills have been studied for decades. Though the effects of mixing soft and hard ores in a mill and their interactions are not widely investigated. To develop a general numerical model for AG/SAG mills, a dynamic model has been introduced, and its capability to simulate multi component ore breakage has been examined and compared with previous publications. The simulation results show that the dynamic model can cover a range of milling conditions and is able to simulate complex scenarios with soft and hard ores. The dynamic model discussed here could provide substantial potential for the controlling and optimization of the comminution circuits. INTRODUCTION In the last decades, efforts have been devoted to studying the comminution circuit due to their high energy consumption. The energy directly spent in minerals comminution was about 2% globally in the year 2000 (Maurice et al, 2003). As one important part of the comminution process, AG/SAG mills are widely used for primary grinding in minerals processing. AG/SAG mill models include static and dynamic models (Kojovic et al, 2012; Yu et al, 2014; Yu et al, 2017; Liu and Spencer, 2004; Salazar et al, 2009). Many static models have been well validated over the past decades, but they are all based on steady state assumptions. Even though plants experience a steady-state condition under certain circumstances, it can be inaccurate to simulate the system by static models under all circumstances (Asbjörnsson et al, 2013). The advantages of a dynamic model are apparent that it provides more information and insights both inside the mill and through interactions with other machines in terms of pebble crushers, conveyor belts, screens and so on. In many mines, the multi-component grinding is inevitable, and the ratio of hard and soft components in the mill strongly affects mills operation and performance. Bueno (Bueno et al, 2010; Bueno et al, 2013) studied the effects of blending hard and soft ores in AG/SAG mills and used them to update the JKSimMet toolkit which was a steady state plant simulation software. However, due to the complexity of the particle interactions such as multi-component breakage function, appearance function, in mill transportation, there has been no dynamic AG/SAG mill models developed yet for simulating multi-component."

Jan 1, 2018

By Klaus M. Hahn, Kurt Aasly, Jutta Lennartz, Hermann Wotruba, Ben Snook, Przemyslaw B. Kowalczuk, Rolf Arne Kleiv

"Seafloor massive sulphide (SMS) deposits have been identified as important marine metal resources for the future. However, literature on mineral processing of SMS is currently limited, and to date, no research has been published on processing of SMS from either active or inactive hydrothermal vent fields on the Arctic Mid-Ocean Ridge. In this paper, individual SMS rock samples from the Loki’s Castle area were tested. Chalcopyrite, isocubanite and sphalerite represented the main copper and zinc bearing minerals in the SMS samples, whereas the gangue consisted of barite and silica. Based on the X-ray transmission response (XRT), i.e. differences in the atomic number of elements in tested samples, and using portable XRF (PXRF) values of elemental composition, individual particles were classified as a either product (low barium / high to low silicon / high copper and zinc) or waste (high barium / high silicon / low copper and zinc). The classification was based on the elemental composition of the samples with the cut-off grade equal to 0.5% for copper. It was shown that the XRT discrimination analysis correlated well with elemental (PXRF) data classification. The results clearly indicate that X-ray transmission sensor-based sorting can be used a useful technique for preconcentration of SMS rock samples. INTRODUCTION Due to different compositions of investigated samples, sensor-based sorting is a useful technique for preconcentration of different materials. The aim of using sensor-based sorting is to upgrade an ore by reducing the quantity of overall waste material reporting to the next processing stage. This can be achieved by eliminating (reducing) the waste fraction. By applying sensor-based sorting, the energy consumption for particle comminution as well as the required process water and reagents can be decreased. The total volume of the waste rejection leads to a proportional reduction in the total energy costs (Lessard et al., 2014, 2016)."

Jan 1, 2018

By Xiaoming Wang

This paper presents an arcuate magnetic separator to remove the grinding ball fragment directly from the mill discharge, which will cause wear to downstream processing equipment such as pump, hydro cyclones and pebble crusher. Furth more this type separator was applied in Wushan mine under China National Group Corporation in China. After months of operation, the equipment has been a success. It removes majority of ball fragments from mill discharge. Keywords: magnetic separator, sag mill, pebble crusher, grinding ball fragments

Sep 1, 2012

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 Yuki Tsunazawa, Shuji Owada, Kazuki Tahara, Shinobu Ogino, Chiharu Tokoro

"Printed circuit boards (PCBs) are an important constituent of waste electric and electronic equipment (WEEE), and contain many electronic components with valuable, hazardous or both materials. Recycling of PCBs is an important subject not only from the treatment of waste but also from the recovery of valuable materials. Demand for rare earth metals is expected to accelerate because of their growing use in next generation high technologies. Since some of these metals are concentrated in a specific electronic component, for example, Ta in capacitors, a special and selective grinding such as parts detachment from the board is effective for the recycling of a part of rare metals. However, direct computer simulation method to investigate a comminution/detachment process of PCBs has not yet been established. In this study, our objective was revealing the mechanism of breakage phenomena in comminution / detachment process of PCBs using computer simulation. A special and selective grinding using an agitation mill promoted the removal of components from a PCB by detachment and was an effective method for the recovery of rare metals. Simulant PCBs on which some capacitors were solder-mounted were used for the comminution test using drum type mill with agitator. To describe this mechanism of the parts detachment process, a computer simulation using discrete element method (DEM) was conducted. Although only an indirect simulation using the spherical particle model was possible for part detachment and board breakage, the particle-based rigid body model could directly represent the behaviour of PCBs. Simulation results successfully corresponded to comminution experimental results."

Jan 1, 2014

By F. Göktepe

Flotation gases and conditioning of the pulp with them are one of the important parameters of flotation and should be taken into account especially in the flotation of sulphide ores. In this study, flotation of pure chalcopyrite and pyrite samples were investigated with air, oxygen and nitrogen as flotation gas and the effect of conditioning with these three gases also were performed. Flotation gas was introduced for 5min, 10min, 15min and 20 min. For chalcopyrite flotation there was no drastic change in recovery when air, oxygen and nitrogen were used as flotation gas but conditioning the pulp with oxygen for 10 minutes increased the recovery about 8% where pulp potential has been approximately 25 mV with chalcopyrite and 150 mV with platinum electrodes. Conditioning with all three gases decreased the pyrite recovery by about 20% with 20 minutes conditioning. Pulp potential decreased in the presence of nitrogen while conditioning with air and oxygen increased the pulp potential for both electrodes. Generally potential increased for both minerals with oxygenation and aeration time but it was stable or slightly decreased with nitrogenation. Comparison of the gases showed that the different flotation gases do not effect flotation recovery but conditioning the pulp with these gases at pre-flotation effects chalcopyrite and pyrite flotation recovery, most dramatically pyrite.

Jan 1, 2014

By Douglas Fuerstenau

"Comminution not only is the major energy cost in mineral processing but it also can limit the grade of ores that can economically be processed. Rittinger first postulated that the energy for comminution is proportional to the new surface produced. Because most of the strain energy needed to initiate and propagate cracks in particles cannot be recovered, researchers reported woefully low comminution efficiencies. Recognizing this, Schoenert proposed that the baseline for assessing comminution efficiency should be the mechanical energy needed to break single particles. After extensive single-particle studies, Schoenert turned to comminuting beds of particle in piston dies. Finding particle-bed comminution to be energy efficient, he had the brilliant conception of making the process continuous, namely his invention of the choke-fed high-pressure roll mill (HPGR). Practical comminution involves masses of particles, which can lead to energy efficiencies far less than that of single-particle breakage. A three-way classification of grinding modes in terms of the mobility of the particle mass provides the necessary insight into the low efficiency of different comminution machines: namely, single-particle breakage, confined particle-bed grinding (HPGR), and loose-bed grinding (ball mill). Examples are given for determining and comparing comminution efficiencies. The size distribution of comminuted products become self-similar, and a single parameter, the median size, can be used to quantify the extent of comminution. The reduction ratio, expressed in terms of the mean size of the feed and product, varies linearly with expended energy and the slope of such plots is a measure of the grindability of the mineral. This approach clearly gives the order of energy efficiency as single-particle > particle-bed > loose-bed comminution. HPGRs are more efficient at low reduction ratios but lose that advantage at higher reduction ratios. Extensive hybrid grinding experiments carried out with our instrumented ball mill and HPGR showed significant energy savings by first comminuting the material in the HPGR and followed by the ball mill. At Cerro Verde an industrial-scale hybrid HPGR/ball mill system is reported to have a 13 percent energy savings over a SAG mill/ball mill system."

Jan 1, 2014

Rotor speed is one of the key hydrodynamic parameters in froth-flotation and it plays an important role in bubble-particle attachment. Laboratory scale studies for optimizing the rotor speed to achieve maximum flotation rate constant (K) of quartz, ground by ball mill, are. Purity of quartz was 99.4 percent and d80 of ball mill product was 230 µm. Each size fraction was separately subjected to flotation at three different rotor speeds, namely, 1200, 1000 and 800 rpm, and the flotation rate constant was calculated. The results showed that the flotation rate constant was high at the rotor speed of 1200 rpm. The flotation rate constants achieved at 1200 rpm were 8.676, 8.232, 7.818, 7.248, 7.068 and 6.984 min-1forthesize fractions of +300, -300+250, -250+212, -180+150, -150+125 and -125+106 µm, respectively. Keywords: froth flotation, rotor speed, flotation rate constant, ball mill, quartz

Sep 1, 2012

By A. G. Bulaev

Biohydrometallurgical technologies based on activity of acidophilic microorganisms oxidizing ferrous iron, sulfur, and sulfide minerals are widely used to extract base and noble metals from sulfide ores and concentrates. As sulfide minerals oxidation is exothermic, industrial processes are usually preformed at 40–50°C. Moderate thermophiles predominate under these conditions. Most of moderately thermophilic acidophilic microorganisms that oxidize metal sulfide are mixotrophic, i.e., they use both organic nutrients and CO2 as carbon sources. Carbon availability is crucial for microbial activity and affects efficiency of biohydrometallurgical processes. Aeration with CO2-enriched air is often used to increase microbial activity in biooxidation reactors. Organic nutrients can be used as alternative carbon source for moderately thermophiles performing biooxidation of sulfide concentrates. We performed several experiments with different sulfide concentrates to study effects of organic carbon sources on biooxidation efficiency and demonstrated that application of such organic nutrients as yeast extract (YE) and molasses made it possible to increase biooxidation efficiency. For example, addition of 0.02% YE in the nutrient medium increased biooxidation rate of pyrite–arsenopyrite gold bearing and chalcopyrite concentrates in batch mode at 45°C. YE addition increased oxidation rate of sulfide sulfur and gold recovery level from 65 to 87% and from 73 to 81%, respectively. Similarly, YE addition increased copper extraction from 47 to 54%. At the same time, YE addition increased efficiency of biooxidation of pyrite–arsenopyrite gold bearing concentrate in continuous mode. Without YE addition, oxidation rates of pyrite and arsenopyrite were 65.7% and 94%, while gold extraction was 71%. YE addition (0.02%) made it possible to oxidize 74% and 95 % of pyrite and arsenopyrite and extract 78% of gold. Addition of molasses (0.02%) similarly affected biooxidation efficiency. Thus, addition of organic nutrients in nutrient media is a promising strategy for improvement of biohydrometallurgical processes.

Jan 1, 2018

By Wei Sun, Ruolin Wang, Jianjun Wang, Xiaodong Li, Honghu Tang, Yuehua Hu, Anh V. Nguyen, Haisheng Han, Kefeng Chen, Zhao Wei

It is difficult to separate scheelite especially from fluorite with fatty acid collectors because the adsorption mechanism of these collectors occurs through chemisorption of the oleate ion onto the mineral surface. A simplified flotation process using Pb-BHA complexes was developed to replace the energy-inefficient Petrov’s process of using a fatty acid, increasing the recovery of scheelite and reducing the cost. The relationship between surface chemical properties (crystal chemistry, solubility, and Zeta potential) of minerals and flotation by using a fatty acid or Pb-BHA complexes was studied in detail to provide new insights into the selective separation mechanism. The results indicate that the scheelite surface exposes more O atoms than Ca and that they are negatively charged due to the anisometric dissolution of Ca and WO4, which provides the possibility for separation using selective interfacial reaction. The FTIR and Zeta potential results indicate that both chemical and electrostatic adsorption play an important role in the adsorption of Pb-BHA complexes on the scheelite surface. The XPS results of the atomic composition and binding energies confirmed the presence of the adsorbed Pb-BHA complexes and that O and Ca may be the active adsorption sites. Therefore, scheelite was able to be collected by forming either a Ca-O-Pbcollector or W-O-Pb-collector (BHA). However, fluorite was only able to be collected by a fatty acid collector and colloidal [H2SiO3]n -, and a high temperature was needed improve the selective desorption of the adsorbed fatty acid collector by forming Ca-[H2SiO3]n - on the fluorite surface, resulting in serious problems in industry. However, the Pb-BHA complexes significantly contribute to improving the recovery of scheelite minerals, simplifying the flotation process, and circulation of the residual reagents and water. The new process has been applied in Shizhuyuan Mine, and improved the recovery by almost 10%.

Jan 1, 2018

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 Subrata Roy

The slag produced in metallurgical smelting processes contains considerable amount of valuable metals. The present work focuses on recovery of copper value by froth flotation from the copper smelter slag. The slag samples are subjected to detailed characterization including automated quantitative mineralogy using Mineral Liberation Analyzer (MLA). The MLA results indicate that a part of copper is present in sulphide form in fayalite (iron-silicate) matrix and very poorly liberated. SEM-EDX analyses also reveal that a certain part of the copper is present within the fayalite (Fe-Ca-Si) matrix, perhaps either as lattice impurity or very fine grain. The copper smelter slag is ground in wet mode in a ball mill, to particle size distribution suitable for flotation. Subsequently, the slurry undergoes froth-flotation in lab-scale Denver-type flotation cell. Various combinations of sodium iso-propyl xanthate (SIPX) and alkyl hydroxamate collectors are used along with pine oil as frother. A multiple collector dosage is required for effective flotation of non-sulphide copper phases associated fayalite and alkyl hydroxamate is identified as one of the effective collector for non-sulphide minerals. The copper recovery can be enhanced by 7-10% with a combination of collectors as compared to conventional sulphide flotation using only xanthate type collectors. However, the grade decreases to some extent. Keywords: flotation, copper slag, hydroxamate collector

Sep 1, 2012