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By Andrzej Luszczkiewicz, Magdalena Duchnowska, Jan Drzymala

A selected flotation system of beneficiation of the copper ore at KGHM Polska Miedz S.A. has been analyzed in the article. It was found that a proper assessment of upgrading must be based on two elements, that is the upgrading process selectivity and working point of the considered flotation unit, both determined, preferentially by means of the Fuerstenau recovery-recovery upgrading curve. The Cu recovery - non-Cu components recovery upgrading curve was selected for calculations because its background lines (no separation and ideal separation) are insensitive to changes in the grade of feed of the processed material. This approach allows a comparison of upgrading results for feeds having different grade, being upgraded in various flotation machines and under different physicochemical conditions. It was shown in the paper that the main criterion for comparison of two working in parallel systems is selectivity of upgrading. However, when two flotation machines, despite of the same selectivity, produce concentrate and tailing of different grades, it is necessary to analyze their working points using upgrading curves. The proper position of the working point depends on the criterion imposed on the process and is a result of not only basic parameters of the upgrading process such as feed, concentrate and tailing grades but also on economic parameters such as costs associated with the production of concentrates and the time needed for their production.

Jan 1, 2014

By L. Gutierrez, M. Jeldres, R. J. Jeldres

"Clays are present in a large number of mineral deposits and are commonly found as gangue. Its complex chemical structure, characterised by anisotropic surfaces, makes its presence a permanent challenge for flotation operations, increasing the reagent consumption, decreasing the quality of the concentrate, and changing the rheological properties of the system. In this context, the main objective of this research is to improve the floatability of chalcopyrite minerals in the presence of clays by using guar gum, a low molecular weight organic polymer, which acts as a surface coating agent for clays. Clay Minerals Society provided the kaolinite sample and the chalcopyrite sample was purified from mineralized rock specimens obtained from Ward’s Natural Science Establishment. Micro flotation tests were carried out in a 150 cm3 Partridge-Smith cell, using compressed air as the gas phase at a flow rate of 80 cm3/min. Potassium amyl xanthate (PAX) and methyl isobutyl carbinol (MIBC) were used as a collector and a frother, respectively. The results showed that the use of guar gum improves the recovery of chalcopyrite in the presence of kaolinite because it induces the formation of clay aggregates that settle by gravitational effects, preventing the 'coating effect' and decreasing excessive collector consumption. pH played a key role in the guar gum performance, which was most effective at highly alkaline conditions (pH 11), where the copper recovery improved from 73% to 90%. The work has significant implications for the mineral flotation in the presence of clay minerals.INTRODUCTION The mining industry is continuously confronted with challenges that alert the sustainability of the sector. There is little availability of water, the grade of the deposits are getting smaller, and the gangue is becoming more complex. Usually, clays are part of the gangue in numerous systems, including copper ore, porphyry, nickel, platinum, etc. (Senior & Thomas, 2005). The structure is mainly composed of layers of tetrahedral silica (T) and octahedral alumina (O) that join in certain proportions: 1: 1 (T-O) and 2: 1 (T-O-T) (Theng, 2012). Also, they expose two crystallographically different surfaces: the faces, which tend to be negatively charged, and the edges, which carry a charge that changes from positive to negative depending on the pH (Van Olphen, 1977). One of the most common clays in copper deposits is kaolinite, whose structure is composed of an octahedral sheet of gibbsite bound to a tetrahedral silica sheet in the ratio 1:1"

Jan 1, 2018

By I. N. Babich

"Complex technological problems associated with the processing of mineral raw materials require the search and development of new means and ways of thinking. At present, computer cognitive graphics (CCG) are one of the most actively developing areas of new information technologies. The aim of the study was to optimize the cycle of technological evaluation of ores at all stages of geological exploration of deposits on the basis of analysis of geological sampling data using CCG. A new approach has been developed that facilitates optimization of the whole cycle of subsoil exploration. At the gold ore deposit, the results of the geological sampling data were processed by the method of constructing the CCG in the form of a histogram showing the frequency of gold extraction and the average amount of its content. Significant peaks of the metal content in the ore, exceeding the level of the average content in the ore by tens of times, have been revealed. Graphical interpretation of the parameters of mineralization reflects the uneven nature of its variability, which indicates the presence of large, rarely occurs of gold in the ore and the need to conduct studies on a sample of ore of greater mass than for ores with tiny gold. On a sample of 50 kg gold-quartz ore studies were carried out on gravity enrichment. The maximum size found in the gold concentrate was 0.07 mm. In the course of integrated tests in a gravity concentrate, gold particles up to 3 mm in size were found, which predetermined the need to include the operation of gravity before flotation. A new approach to subsoil research is protected by a patent (RU 2620823).The technological problems that arise before the researcher associated with the processing of resistant ores require the exploration and development of new means and ways of thinking. New problematic situations on complex mineral and raw materials objects are practically not amenable to resolution by existing methods. Integration of industrial and information technologies is necessary. At present, computer graphics (CG) is one of the most rapidly developing areas of new information technologies. For example, in scientific research, including in fundamental research, the accent from the illustrative function of CG (the visualization of what is already known) is increasingly shifting towards the use of computer cognitive graphics (CCG) tools (Bashlykov, 2016). The function of the CCG is to obtain a new knowledge with the help of a graphic representation - a cognitive image or at least to promote the intellectual process of the logical acquisition of this knowledge. In this study, cognitive images are used to graphically represent the distribution of valuable components in the bowels of the deposit, characterizing the state of mineral-raw materials."

Jan 1, 2018

By O. Guven, I. Karaagaçlioglu, O. Ozdemir, M. Çelik

In this study, the effect of morphological properties such as shape factors and roughness of the glass beads on their flotation efficiency were determined using image analysis and profilometer methods. There is a considerable correlation between the shape factors, surface roughness and flotation behavior of the glass sample. These results indicate that as the particle shape is away from roundness and smoothness, it acquires more hydrophobicity.

Jan 1, 2014

By Antoineta Boteva

A significant part of the currently production of the non-ferrous and precious metals is from sulfide ores. Character feature of sulfide ores is the presence in them always pyrite and wide range of different sulfide minerals else. These minerals are the carriers of valuable for industry metals. Due to the low content of the main components, very often call on the use of collective- selective flow-sheets. The extraction of minerals in the collective concentrates determined in a large extent the effectiveness of the collective-selective sheets. In conditions of bulk flotation kinetics to floatate of the various minerals is different. Due to why it is and how it can be used for a more effective selection of minerals ?this is the main task of this report. For this purpose are used results from the bulk flotation of pyrite, copper sulfides, molybdenite, galena, blenda. It is separated and place of host rocks. Base it of large experimentation material, including both electro-kinetic measurements of mineral systems, as well as laboratory flotation tests and factories monitoring it is established kinetics of flotation of mineral particles in conditions of collective flotation. Made an effort to clarify the effect as of the species and the proportion of different sulfide minerals involved in flotation pulp else. Traced was the impact of the density and aeration of the flotation pulp on deferens in kinetics of mineral flotation in condition of balk flotation. The obtained results are used to increase the efficiency of the diffraction flotation of the complex sulfide ores containing precious metals. In the schemes, it is possible precious metals to fall in the most appropriate for the next processing products. Keywords: flotation, sulphide ores, kinetic extraction

Sep 1, 2012

By Valery V. Kostjuk, Victor. N. Bredikhin, Alexander I. Shevelev, Evgeny A. Kazban

"The investigations to improve the process data have been done in order to stabilize the functioning of drying units. The scheme of turnings preparation with centrifuging and subsequent thermal degreasing (tandem) is proposed. To improve the efficiency of the process the scheme of reclamation of the centrifuge fugate is developed with production of oil and service circulating water. Empirical dependences of the turnings temperature influence on the lubricant-coolants content in centrifuging are gained. When the turnings temperature is increased to 80 C the residual content of LC is decreased by 1.5%. The investigations aimed to improve the preparation of non-ferrous turnings have allowed to decrease the melting loss by 15-20%; to stabilize the process of thermal drying of turnings; to decrease sharply (by 60- 70%) the volume of LC combustion products; to reclaim the centrifuge fugate and produce oil and servicecirculating water.Non-ferrous turning and primarily aluminum and copper alloys turning is a stable source of secondary raw materials for metallurgical works.Direct by lubricant-coolants (LC) of various types: synthetic, semi synthetic, oily and emulsions.On the base of investigations concerning various methods of the non-ferrous turning processing the favorable one has been selected taking in to consideration the economy, ecology and quality of the finished product (alloy). Two-stage process is developed. The main idea of the process is the elimination of the lubricant-coolants (LC) to the limit specified in advance. The applied method is centrifuging with subsequent final elimination of LC by thermal method.Constant value of LC content at the inlet of the thermal unit excludes practically the oxidation of metal and as a consequence increases the output by 10 –15 % in metallurgical processing."

Jan 1, 2003

By S. M. Javad Koleini

The aim of this research is to extract zinc from complex lead and zinc ore containing carbo- silicate lead and zinc minerals using sulphuric acid. Samples, taken from Dareh Zanjireh mine located in central of Iran, were subjected to leaching tests after calcination process. Experiments were planed according to the Taguchi statistical method. The calcinated samples contain 13.98% zinc and the constituting minerals being dolomite and zincate. Various parameters such as speed of mixing, temperature, time, solid to liquid ratio and pH were studied. A solid to liquid ratio of 1:6 gr/mL at 60°C and 800 rpm speed of mixing for 30 minutes resulted in a product with 85.96% zinc recoveries.

Jan 1, 2014

By M. Saghaeian, R. Hejazi, L. Hosseini, M. Zare

Difference between plant feed specifications in practice and design feed is a problem that most of processing plants face during operating and commissioning. This topic has led to inappropriate operating and necessitates repeating the basic tests on new feed. Gol-E-Gohar fourth concentrate line with a capacity of 2 MTPY, located in Kerman province, is the first iron concentrate plant in Iran in which High Pressure Grinding Roll (HPGR) technology has been applied. Plant&apos;s feed consists of 30% AG mills pebbles of lines 1-3 and 70% run of mine crushed ore whose Fe=51%, Fe/FeO=2.5, S=1.7% and work index=15 kWh/t. Desired concentrate has Fe>68% and S<0.7%. After the plant construction and operation commencement, providing design feed was not possible due to the crushing unit`s not being complete, therefore the plant was fed by AG mills pebbles. For predicting optimal conditions of the plant and investigating the possibility of improving the current concentrate specifications, sampling from the new feed and laboratory and pilot tests was performed again. Studies showed that new feed has Fe=41%, Fe/FeO=3.5, work index=17 kWh/t. Results of laboratory tests with Davis tube device and pilot tests run using magnetic separators with simulating the plant`s circuit showed that with current feed, achievable recovery in industrial scale would be 75.52% which compared to plant&apos;s recovery in studied period (75.94%) shows that plant operated in optimal conditions. To improve the current concentrate specifications (Fe=66%, S=1.03%, Ferec=75.94%) and for achieving desired concentrate, samples were reground to four fractions with k100= 300, 212, 100, 45 and Davis tube tests were performed on each of the samples separately. Results showed that the fraction whose k100=212 µm or k80=200 µm has respective Fe and S grades of 68.27% and 0.681% which are consistent with the desired concentrate.

Jan 1, 2014

By T. M. Bhatti

The main purpose of present study was to characterize the dissolution of uranium from low-grade black shale with indigenous isolated strain of Acidithiobacillus ferrooxidans (BSAF-01). The nature of shale is quartzite-schistose and contains uranium content of 0.005% U3O8 (50 ppm U3O8). Uranium is present in the tetravalent oxidation state (U4+) in the shale matrix. The main minerals identified are graphite, quartz, pyrite, mica minerals (phlogopite, biotite, sericite, and chlorite), microcline, K-feldspar and kerogen (hydrocarbon-compounds). Bacterial oxidation of pyrite was an acid-generating system and produced sulfuric acid and ferric sulfate during this biological phenomenon. A series of bioleaching experiments were conducted in shake flasks for leaching of uranium from black shale. The leaching experiments were performed at 50% pulp density using indigenous Fe- and S-oxidizing bacterium (Acidithiobacillus ferrooxidans). Bioleaching data revealed that about 90% ~ 95% U3O8 was leached out from black shale ore. Uranium dissolution from shale depends on pH (pH 1.5~1.9), redox potential (=500 mev) and the concentration of Fe2+ and Fe3+ ions in the leaching environment. The oxidative leaching of U4+ involves a redox reaction with Fe3+ as an oxidant and bacterial re-oxidation of Fe2+ in acidic leaching environment. Uranium leaching efficiency was attributed to the sulfuric acid and ferric sulfate production during bacterial oxidation of pyrite.

Jan 1, 2014

By Y. Y. Li, Q. Chen, Y. X. Cai, Q. Zhang, S. Mao

"Due to the influence of combustion conditions, the fly ash produced by some power plants has the problem of high-carbon content. The unburned carbon in fly ash can be removed by flotation, and the decarbon tailings should reach the national standard level I fly ash. The fineness of the requirement is one of the important indicators and is also an important factor affecting the tail ash activity. In this paper,adopting two methods investigate the effect of particle size on the flotation index: one is direct flotation of fly ash, and the other way is wet grinding + flotation of fly ash, comparing the two methods and selecting the appropriate process,which provides a way for the effective utilization of fly ash. INTRODUCTION Fly ash is a solid waste discharged from coal-fired power plants. The annual amount of emissions of fly ash are very large in China. The amount of fly ash were discharged from coal-fired power plants are increasing gradually, and the amount of fly ash stored has exceeded 2.5 billion tons, but the comprehensive utilization of fly ash is not high, which brings about a huge environmental problems( Lu et al.,2011). Carbon is a harmful component of fly ash in cement and concrete application (Zhang et al.,2008). Fly ash decarburization is an essential link to improve the utilization efficiency of fly ash and the reduce pollution ( Yang et al.,2012). Carbon is selected from fly ash to make full use of fly ash resources and improve utilization of fly ash (Li et al.,2008). In this paper, the flotation decarburization of high-carbon fly ash is studied, through comparing the grinding and not-grinding processes, optimizing the separation process of fly ash, which provides a way for the effective utilization of fly ash."

Jan 1, 2018

By Nicolás Caussade

"The IMPC 2014 slogan "Optimizing Water and Energy Usage for Sustainable Mining" refers to the ever decreasing availability of fresh water and energy, which has turned out to be a crucial aspect in assuring the competitiveness of the mining sector in Chile and the Andes region in general. The concern for sustainability and the supply of water and energy is nowadays part of the top priorities of mining countries and communities. This is also the case for Antofagasta Minerals. Several years ago its mining group implemented an energy policy based on intelligent, strategic and sustainable management, in order to successfully face the challenges imposed by the market. It is called an intelligent policy because it intends to provide energy through a diversified range of sources, which includes the development of in-house alternatives. It is also a policy focused on efficient energy consumption and one that is strategic. Because it is in line with the characteristics of the mining activity, it is developed for the long term. Finally, what makes the policy sustainable is that it gives priority to energy usage from renewable resources and as such, the required capacities have been developed to generate innovative solutions that respond to the restrictions that characterize the industry today."

Jan 1, 2014

By l. Bokányi, T. Varga

"The recycling of waste car tyres is a very important environmental task. The waste tyres usually are re-used or recycled by thermal processes like pyrolysis, gasification or incineration. The main problem associated with these processes is the sulphur content of waste tyres originated from the vulcanisation process, which pollutes the environment and the valuable products (i.e. pyrolysis oil) as well. In our research the desulphurisation of waste, mechanically prepared tyre sample was systematically investigated by the biosolubilisation with Acidithiobacillus thiooxidans, strain Karitas. Parallel, the experiments with sterile 9K nutrient medium were also carried out. It was found that the vulcanisation sulphur can be solubilised due to both the bio- and the chemical leaching, although the bioleaching is more effective. The solubilised vulcanisation sulphur then forms precipitates. The precipitates are forming in the bulk solution, as well as on the surface of rubber particles. The origin of the precipitates was investigated using XRD and scanning microscopy with micro probe. The origin of the precipitates is different: while in the process of the vulcanisation sulphur solubilisation with 9K medium the jarosite (KFe3+3(SO4)2(OH)6) forms, the course of the biosolubilisation with Acidithiobacillus ferrooxidans Karitas is accompanied by the formation of the jarosite and the halotrichite (FeAl2(SO4)4 · 22H2O) as well. The formation of the latter is the biomineralisation. The mechanisms of the bio- and chemical solubilisations are rather different as it was found and experimentally proved by several tests, and depends on the retention time of the solubilisation. Special efforts were done to elaborate the proper separation of the precipitates from rubber particles. Combination of intense dynamic stirring and recycling flotation process to remove the precipitates was applied for this purpose. The surface properties of synthetic jarosite were revealed using zeta-potential measurements at different pH and in presence of collectors. The parameters of the flotation were chosen based on the revealed surface properties of the precipitates. Finally, the sulphur recovery of the recycled rubber was achieved as low as <0.5%, sulphur content of it 0.17%, 12-times lower than that of the waste tyre sample after mechanical preparation."

Jan 1, 2018

By A. V. Rasskazova

"The oxidized and mixed ores are processed by heap leaching. Primary ores with high gold content are floated. In recent years mining of primary ores with the low gold content (up to 4 ppm) has increased. Extraction of gold from these ores by floatation is technologically ineffective. Gravity concentration is ineffective for fine gold particles because of their floatability. The research objective was assessment of the viability of processing gold-bearing ore with combined gravitational and hydrometallurgical methods and testing of recovery of metals from a gold-copper oxidized ore chloride-hypochlorite leaching solution. The advantage of chloride-hypochlorite lixiviant is the low cost of reagents which is produced by the electrochemical synthesis of NaCl solution with the addition of HCl. The adsorption of chlorine compounds by a mineral matrix and its ability to oxidize the refractory ore components and allows for the application of chloride-hypochlorite systems for gold recovery for both oxidized and primary ores. The complexity and problem in using a gold–chloride system is the strong adsorption of gold–chloride complexes onto mineral surfaces, such as goethite, quartz, and alumina. In preliminary testing, gold recovery from gravity circuit gold bearing concentrates processed by agitation leaching in chloride-hypochlorite solution, gold recovery has reached up 82% after 4 hours of leaching. Chloride-hypochlorite leaching of copper-gold oxidized ore with preliminary processing by sulfuric acid provided for 94 % gold recovery to solution. Understanding of ecological hazard of cyanides is the motive power of researches in the field of search non-cyanic chemistries to provide for technologically and economically effective solvents of gold. Soluble compounds of chlorine with a suitable oxidizer are one of the alternatives to cyanides. Basic researches of gold extraction by chloride-hypochlorite solution have shown high rates of gold recovery.INTRODUCTION Because of the continued and growing environmental concern for the use of cyanide for gold processing, interest for the use of non-cyanide lixiviants, especially with halides has renewed recently (Tran et al., 2001; Ferron et al., 2003; Bhaghalha, 2007). Leaching solutions based on halides (chloride, bromide and iodide) are viable alternative to cyanide (Kwang et al., 2008). The major disadvantage of the chlorine–chloride system is the high reactivity of chlorine in reaction with sulfide and gangue carbonate minerals. It is believed that only high grade materials may be treated by chlorine–chloride systems economically (Baghalha, 2007). Another important problem of the application of gold–chloride complex is that it tends to be rather unstable and may re-precipitate upon contact with a reductant, such as sulfidic minerals of ore. It is well known that Au(III)–chloride hydrolysis species are strongly adsorbed by goethite, quartz, and alumina (Machfsky et al., 1991). To minimize adsorption of gold–chloro complexes, it works best to minimize the adsorption time."

Jan 1, 2018

By G. V. Sedelnikova

Biohydrometallurgical studies were performed on the sulfide gold-arsenic concentrate obtained in treatment of refractory ore from a deposit located in northern Russia. Gold is disseminated in sulfides-arsenopyrite, pyrite and antimonite (their content is 10.0%, 30.4% and 0.7%, respectively). Gold extraction is only 11.8% by cyanidation. Results are given for test bacterial oxidation of the concentrate in continuous mode at temp. = 28~32°C using mesophilic bacteria and at temp. = 32~38°C using the association including moderate thermophilic bacteria. The paper shows that the use of moderate thermophilic bacteria allows to speed up sulfide biooxidation and reduce its time to 96 hours compared to leaching at temp. = 28~32°C for 110~120 hours. The optimal range of pH = 1.5~2.0 of biooxidation process was determined where bacterial solutions are produced with the molar ratio Fe:As > 3 necessary for precipitation of hard-to-solve, environmentally safe arsenical precipitates. Electron microscopy showed that sulfide biooxidation results in liberation of disseminated gold with nanoparticle-level sizes. High sorptive activity of carbonaceous matter and other compounds of bacterial residues cause low gold extraction into cyanide solution ? 28.7%. 10% resin load makes it possible to extract 88.1% Au. Aeration of pulp in calcareous medium enhances extraction to 95.7% and decreases cyanide consumption from 17kg/t to 8 kg/t.

Jan 1, 2014

By Susanna A. C. Stadler, Chris Aldrich, Jacques J. Eksteen

"Slag foaming occurs in several pyrometallurgical processes. These processes include steelmaking in basic oxygen steelmaking furnaces and electric arc furnaces as well as various non-ferrous operations like sulphide smelting/converting and base metal slag cleaning. Although slag foaming in steelmaking processes has been extensively researched, little attention has been given to slag foaming in non-ferrous operations. Slag foaming phenomena are complex because often the system consists of three or more phases. With this in mind, factors previously identified as influencing slag foaming were investigated. These include the slag basicity, physical properties of the slag, namely viscosity, surface tension and density, the formation of particles due to undercooling of the slag and the FexO concentration in the slag.Slag foaming was investigated in a vertical tube furnace. The different slags were contained in alumina crucibles and bubbling argon gas through the molten slag induced foaming. The foam height was measured by using stainless steel probes and a voltmeter. The conductivity of the slags made it possible to measure the foam height from the position of the probes when the electrical circuit was completed. Slags were foamed at different temperatures to investigate the effect of solid precipitates.The effect of increasing FexO concentration was found to decrease the foam index due to lower viscosities, but higher surface tension depression appears to have led to increased foam index values at high FexO concentrations."

Jan 1, 2003

By Luo Chuansheng, Rao Jinshan, He Xiaojuan, Qiu Xianyang

The dissemination grain size of chalcopyrite is really fine and refractory grains of -10µm take up 25%. Dissemination relationships among chalcopyrite with pyrrhotite, pyrite, marcasite and gangue minerals are complex. Content of Fe-bearing sulphides and Fe-bearing silicates associated with chalcopyrite reaches to about 60%. It’s hard to liberate and separate chalcopyrite from pyrrhotite. The above four are the main mineral processing difficulties of a copper ore in China. Because of the similar floatability and poor separation effect between chalcopyrite and pyrrhotite, enhanced depressing and collecting method was adopted in Cu-S separation before 2009. Due to the different magnetism among chalcopyrite, pyrrhotite and Fe-bearing silicates, magnetic separation is creatively induced in Cu floatation circuit based on the in-depth study of process mineralogy. High efficiency and new Cu-S separation technology of "Rough concentrate regrinding-pyrrhotite rejecting from middling by magnetic separation" and a highly selective copper minerals collector YL-1 had been developed to solve the difficult problems of refractory Cu-S separation, which are heavy load of middling recirculation,difficulty in upgrading Cu concentrate, unstable locked cycle and low separation indexes. And grade of Cu concentrate has been increased by 3.33%, recovery of Cu and Ag has been increased by 19.32% and 10% respectively.

Jan 1, 2014

By Yuri Yemelianov, Stanislav Balikov, Alexander Epiforov, Andrey Boldyrev, Andrey Bogorodsky

"Test work was carried out using copper gold-bearing flotation concentrate with 6.85%Cu, 14.30%Fe, 20.70%S and 2.34%As. Gold and silver grade in the concentrate is 54.6 g/t and 92 g/t, respectively. Gold and copper are valuable components in the concentrate. Gold is partially associated with pyrite and fahlores. Copper in the concentrate can be found as tennantite (Cu12As4S13). The 71% of gold from the flotation concentrate is recoverable by cyanidation with simultaneous cyanide consumption in the amount of 96 kg/t. The major reason of refractoriness is that gold is fine encapsulated into sulfides and the presence of cyanicide-copper. The concentrate ground as much as 95% minus 10 µm was treated using low-temperature POX at the temperature of 100±5°C, L:S ratio of 5:1 and the process time of 1-5 hours. Residual sulfide sulfur in the cake is 2.28% which is 89% sulfide oxidation. The highest copper recovery to POX solution is 91%. It was found that gold recovery to cyanide solution is 85-94% during alkaline pre-treatment of POX cakes followed by cyanidation. In this case, cyanide and lime consumption is 75-90 kg/t and 120 kg/t, respectively. In order to recover precious metals from POX cakes leaching using sodium sulfite was carried out. Test work was conducted at varied reagent concentration, L:S ratio and leaching time. Gold and silver recovery achieved was 85-95% and 59-63%, respectively."

Jan 1, 2014

By P. C. Beuria

Iron ore concentrate contains different mineral phases viz. hematite, magnetite, goethite, kaolinite, and gibbsite. Presence of some of these phases like goethite, kaolinite, and gibbsite contribute to the loss on ignition (LOI) content of the sample. Iron ore fines (pellet feed) are pelletized for utilization in DRI & BF processes. In the present pelletization technology i.e., straight grate and grate kiln processes, the LOI in the ore should be within the range of 2.0-2.5%. LOI content in the iron ore concentrate is found to be more than 4% after beneficiation of low-grade iron ore. It is therefore difficult to produce good quality pellet because of high LOI content. The LOI content of the sample is a detrimental factor in the pellet making. For effective pelletization, the LOI content in iron ore fines needs to be reduced before pelletization. It can be reduced by fluidized bed roasting. The objective of present work is to understand the kinetics of removal of LOI from iron ore fines. The effects of bed depth, temperature, and residence time on reduction of LOI content in iron ore fines were studied using muffle furnace. The process of roasting was carried out at four different temperatures varying from 400 to 950 °C with a variable residence time of 30, 45, 60 & 75 minutes and at bed depths of 16, 32, 48 & 64 mm. In all instance of experiments carried out, one of the parameters was kept constant. It was observed that at 850 °C and 30 minutes of residence time, there was sufficient removal of LOI in static bed condition even at a high bed depth of 64 mm. Keywords: LOI, pellet feed, fluidized bed roasting, goethite

Sep 1, 2012

By Luis Cáceres, Genny Leinenweber

"We have designed a planar perpendicular flow cell for electrochemical measurement of a mineral available as a fine powder. The working electrode consisting of mineral powder supported on a carbon paste surface as a 4 mm diameter disk, was concentrically positioned inside a vertical tubular reactor. The counter electrode was a 316L tube embedded in the body cell. The supportive media was a 1.2:1 mixture of candle wax and graphite powder respectively, which is a good electrical conductor. The concentrate electrode as a film attached on a carbon paste disk was prepared rubbing the surface carbon paste against dried powdered mineral. An Ag/AgCl 1 M KCl cell as a reference electrode was attached to the body cell by using a fast coupling fitting. A stable flow rate was achieved using a frequency inverter to drive the pump motor. The flow through the cell verified to be laminar due to the Reynolds number in the cell flow passage. Cyclic voltammetry from - 1200 a 600 mVSAgE were measured using a carbon paste with and without mineral attached to the surface. The main findings of this work were: a). Electrochemical measurement of mineral powder in contact with flowing samples was easily achieved using ground mineral. This is important where massive samples are not available. b). The voltammetric curve features of ground mineral coincided with reported data. c). The working electrode could be quickly replaced while maintaining very good reproducibility."

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