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By Tsvetan Damyanov, Nikolay Hristov, Evgeni Kostadinov, Lubomir Kuzev

"The process of grinding in drum mills is directly dependent on the dynamic forces occuring in the free movement of the grinding bodies in the volume. The subject of discussion are the potential impacts between grinding bodies having different shape and equal weight in a drum mill that has a diameter of 1200 mm. The study utilised ball grinding bodies having a diameter of 120 mm and tetraballpebs having a conditional diameter of 120 mm. The study was carried out using the Solid Works Simulation software. The following cases were examined: • Impact between two identical grinding bodies; • Impact between a grinding body and the shell surface. The study provided numerical values for impact force, kinetic energy of impact, linear speed of impact, linear displacment of the center of gravity and duration of impact deformation. The impact force of the balls is approximately 179000 N. The impact force of the tetraballpebs with typical vertices, edges and spherical surfaces depending on the area of impact is 177000 to 185000 N. Upon impact between two spherical surfaces of tetraballpebs, the contact area is 263.55 mm2, which is more than twice the contact area upon impact between two balls, which is 114.39 mm2. This determines better conditions for the transmission of kinetic energy by reducing opportunities for overgrinding."

Jan 1, 2014

By Lei Pan, Roe-Hoan Yoon

"Direct force measurement for bubble-particle interaction has been difficult due to bubble deformation, which makes it difficult to know the separation distances between the two macroscopic surfaces. In the present work, we have developed a method of monitoring the deformation accurately, while directly measuring the interaction forces. In effect, we can ‘see’ bubbles interacting with mineral surfaces under different hydrodynamic and chemical conditions and determine both the hydrodynamic and surface forces involved. In the present work, a high-speed camera has been used to record the optical interference fringes of a thin liquid film (TLF) of water formed on a mineral surface. The recorded fringes are then used to reconstruct the spatiotemporal profiles, from which one can determine the hydrodynamic pressure using the Reynolds lubrications theory. From the forces directly measured in the present work and the hydrodynamic pressures obtained from the fringes, we have determined the disjoining pressure. The results show that air bubbles interacting with hydrophilic surfaces form stable TLFs with zero contact angles. The TLF formed on a hydrophobic surface thins fast, form a ‘pimpled’ film, and ruptures to form a finite contact angle. The new information obtained in the present work may be useful to better understand the role of hydrodynamic and surface forces affecting bubble-particle interactions."

Jan 1, 2014

By Janusz S. Laskowski

"Frothers offered by different manufacturers are marketed with some information on their chemical and physical properties (e.g. density, viscosity, color, water-solubility, safety/toxicity, etc.). But frothers are used in flotation to generate fine bubbles and to stabilize the forth, and this information is only provided in a very qualitative description of the visual appearance of bubbles and froths. The terms “powerful” and “selective”, which have been commonly used to characterize frothers, have intuitive rather than scientific meaning.This paper introduces the DFI (Dynamic Foamability Index) plotted vs. CCC (Critical Coalescence Concentration) diagrams to classify flotation frothers (Fig. 1). The frothers characterized by low CCC and high DFI values have properties of strong flotation frothers, while those with high CCC and low DFI values are more selective. The proposed frother classification system, based on simple CCC and DFI measurements, provides, for the first time, a solid ground-work for characterization of the flotation frothers."

Jan 1, 2003

By Alejandro Yañez, Martta Nousiainen, Rodrigo Grau

"Gas dispersion plays a fundamental role in froth flotation. Gas dispersion in flotation is quantified by using four properties: gas velocity, bubble size, gas hold-up and bubble surface area flux. Gas dispersion measurements were conducted in three flotation cells: TankCell 1, TankCell e300 and TankCell e500. The measurements reported in this paper were carried out exclusively in two-phase systems using only water and air at frother dosages exceeding the Critical Coalescence Concentration (CCC) in order to prevent bubbles from coalescing. The measurements conducted in TankCell 1 and TankCell e500 were conducted by Outotec specialists, whereas the characterization of TankCell e300 had been conducted earlier in 2008 by a team from McGill University. When working in two-phase systems and under non-coalescing conditions, gas dispersion characteristics measured in different scales can be compared directly. The measurements conducted in TankCell e300 are taken as a base line in order to compare the performance of TankCell e500, whereas TankCell 1 is a pilot-scale flotation cell which is used in rotor testing. The gas dispersion properties in TankCells were found to be affected by the air flow rate and rotor tip speed. Bubble sizes (d32) measured on the three-size scale seem to be within the same range of 0.6 mm to 1.6 mm. It was noted that the bubble size was influenced by rotor tip speed and gas velocity. In general, as the rotor tip speed increased, the bubble size decreased and as the gas velocity increased, so did the bubble size. The rotor tip speed also has an impact on the hold-up; in general, as the rotor tip speed increased the gas hold-up also increased but the influence of air flow rate on gas hold-up was greater. Bubble surface area flux was found to vary between 40 and 85 1/s. As the gas velocity increased, the bubble surface area flux also increased."

Jan 1, 2014

By V. F. Petrov

Cyanide is widely used gold lixiviant for hydrometallurgical processes. The resulting tails contain complex toxic compounds. With reference to this, the protection of the environment should be the major issue. A complete detoxification of cyanides before disposal, a partial detoxification to the allowable concentrations and a disposal of tails at a polygon followed by the detoxification of excess water into the environment are offered as an environmentally friendly way of disposal. However, a complete detoxification of the cyanidation tails does not give the required results due to the presence of toxic compounds, cyanides and thiocyanates in tailings ponds. This is due to adsorption-desorption process occurring between solid and liquid phases. A partial detoxification is used to down cyanide to the allowable concentrations, which are safe to the environment. The storage of tails without detoxification is mainly used at low concentrations of toxic compounds in the disposed tails. With reference to this, water recycling is practiced by Russian plants in order to reduce as much as possible or almost eliminate toxic effluents into the environment. Fresh water is applied if necessary and to make up for water losses, with 8-12% of total water supply. This allows for the stability of water balance and the decrease of consumption of the reagents applied. The conditioning technologies of water recycling followed by regeneration of free cyanide and metals recovery as saleable concentrates are specially developed due to adverse impact of water recycling on gold recovery processes due to high concentration of base metals (copper). These technologies are also profitable. In order to detoxify cyanide in the tails for tailings dam, effective and inexpensive technologies involving a seasonal use of detoxified reagents were developed. For example, a technology with aldehydes use which is applied by a series of operations. Effluents disposed to the environment are detoxified using chlorination followed by almost a complete destruction of toxic cyanides and thiocyanates. Before disposal, chlorinated water is settled to precipitate the resulting hydroxides of metals and complete chemical reactions such as a full decomposition of hypochlorite ions. In order to protect ground water, watertight screens from local water-resistant materials are used. The samples of these materials were previously tested and chosen according to their maximum ability to adsorb toxic compounds in the tailings pond. If local water-resistant materials are not available, whole welded impermeable polymer screens are used. The options mentioned allow the storage of cyanidation tails in accordance with national ecological standards. Keywords: cyaninides, thiocyanates, wastes, environmental safety, recycled water-supply, detoxification, storage

Sep 1, 2012

The reactivity of clay minerals and variety of these reactions are greater than any other known colloidal material. While it is acknowledged that clay minerals can cause problems in mineral flotation, the literature contains conflicting evidence, particularly with respect to the effect of clays on froth stability. It is well known that achieving and maintaining optimum froth stability is an influential factor in determining froth flotation performance. However, the presence of clay minerals in the ore is a major challenge to obtaining a stable froth. In fact, clay minerals could reduce froth flotation performance by both decreasing and increasing froth stability. The mechanism by which clay minerals affect froth stability is not fully understood and needs to be investigated further. In order to improve flotation performance, reliable knowledge of the effect of clay minerals on froth stability is essential which is discussed in this paper. Keywords: froth flotation, froth stability, clay, clay minerals

Sep 1, 2012

By C. R. Mambote

One of the processes developed for vanadium recovery from the fly ash of crude oil is through acid leaching. In the process, iron is one of the impurities that should be removed before vanadium precipitation, due to the fact that iron tends to co-precipitate with vanadium. The mechanism of iron precipitation is understood in terms of ferric hydrolysis, followed by the dimerization and subsequent polymerization of the crystalline iron compound. In order to develop a new approach for the fly ash processing, in the present paper the precipitation of iron from the liquor after the leaching process was studied with addition of NaOH or NH4OH in the presence of H2O2 or Na2C2O4 at 80°C. The objective was to investigate the feasibility of the selective precipitation which could be applied to vanadium and nickel recovery from the fly ash. The experimental results show the difficulties of removing iron by precipitation without co-precipitating nickel and vanadium.

Jan 1, 2014

By Christopher Tucker, Marcello Veiga

Social issues are increasingly recognized as significant inhibitors to mineral development projects. Increasingly social risk is being recognized as a key factor determining the success of a mineral investment. Groups opposed to a mine for social or political reasons often use environmental impacts, real or perceived, to prevent mine development. These risk factors depend largely on cultural perceptions of mining activities and must be understood as such in order to be appropriately managed. A first step to addressing social issues is inclusive, transparent and meaningful engagement of stakeholders. This process allows stakeholders to understand what the other parties value in order to collectively establish a common currency for development and the creation of mutual value. Expanding the scope of benefits and values a mine can bring is of increasing importance to mining companies who typically consult outside specialists remote from the mine site and late in the development timeline for this purpose. Training technical staff, engineers and geologists, who make initial and ongoing contact with local interests, in a holistic approach to mine development is crucial to successful and economic mineral development projects. Further extending this conversation to the general public, media governments and non-governmental organizations is a necessary step in developing a meaningful discourse on the benefit of mining activities.

Jan 1, 2014

By Chi Zhang, Junyi Wu

"With the increasing popularity of lithium cobalt oxide in lithium ion battery industry, which is driven by new energy vehicle and mobile device applications, the demand of cobalt is also growing rapidly in recent years. There is a significant trend of increasing investment on cobalt capacity in China, and the automation renovation is considered as an option of improving production efficiency. This study aimed at evaluating the practicability of stainless permanent cathode blank and automatic stripping process in cobalt electrowinning process. The purpose is to replace the old starter sheet process in cobalt electrowinning, which so far was used by most of cobalt refineries in China, but very labor intensive and exposed operators to serious aerosols that contained both cobalt and acid. In the old starter sheet process, the initial cobalt starter sheet is produced onto a plate made of titanium, while the titanium cathode blank and hanger bar fit the critical corrosive environment but is lack of mechanical strength for automatic production which has been mature in copper electrowinning process. To evaluate the proper materials instead of titanium, the coupon corrosion tests with different raw materials including 316L and other stainless steel grades were held for several months in production environment at a cobalt tank house in China. Following the comparison between titanium and other tested materials, a pilot production test in a cobalt tank house is also on-going.INTRODUCTION Cobalt has been known in early China and used in pottery glazes, and the ancient Greeks and Romans used its compounds to make colored glass since long time ago. The blue on the colored porcelain from the Tang Dynasty in China was also due to the presence of cobalt compounds. The word cobalt is known being derived from the German kobalt, from kobold meaning ""goblin"", because the cobalt-bearing blue ore, CoAsS, was called kobaltin in Europe in the Middle Ages, it may have been thought to be harmful to the health of the miners because of arsenic in the ores."

Jan 1, 2018

By James A. Finch, Xiangzhou Ding, Yue Hua Tan

"The Jameson Cell is one of the choices of flotation machine in coal, base metal processing and other specialist applications. This paper determines the effect on vacuum pressure and bubble size of two design variables, orifice size and downcomer length, and the operating variable air-to-water (AWR) ratio. The main findings are: orifice size and downcomer length impact the vacuum but have limited effect on bubble size; AWR < 1 favours high vacuum, conditions are identified where vacuum is maintained at AWR > 1, and water flowrate has slightly greater impact on bubble size than air flowrate.INTRODUCTIONFroth flotation, the most common technique for mineral separation, has been in use for over a century. The process takes advantage of the difference in wettability of mineral surfaces to achieve the separation of valuable minerals from non-valuable minerals, or gangue. Numerous flotation machines have been invented and patented over the years. The Jameson Cell, invented by Professor Graeme Jameson in the late 1980s, is one successful example. First trialed at Mount Isa Mines (Queensland, Australia), Jameson Cells have been installed at operations around the world for the recovery of fine coal (Mohanty and Honakeri, 1999; Cowburn et al., 2006; Hacifazlioglu and Toroglu, 2007; Uçurum 2009), minerals of copper (Farr 1992; Atkinson et al., 1993; Harbort et al., 1997), lead/zinc (Rohner, 1993; Munro, 2003) and gold (Bennett et al., 2012; Lauder et al., 2003), and in water treatment (Yan and Jameson, 2004), solvent extraction de-oiling (Miller and Readett, 1992; Miller et al., 1997; Harbort et al., 2003; Young et al., 2006), oil sands processing (Neiman et al., 2012), and various food industries (Brenneman, 2014). One of the largest units is the 650 cm diameter separation tank with 24 downcomers installed in an Anglo American operation (Osborne and Euston, 2015). Scale up is relatively straightforward: to increase capacity the number of downcomers is increased with corresponding increase in size of separation tank.The Jameson Cell comprises two main parts: a vertical tube (downcomer) which provides self-aspiration and intense bubble-particles contact, and a (separation) tank where particle-bubble aggregates disengage from the pulp. The intense bubble/slurry mixing in the downcomer with air holdups reaching 60% (Marchese et al., 1992) accelerates particle collection enabling the greatly reduced cell volume compared with mechanical flotation cells and columns. The disengagement of the particle-loaded bubbles from the slurry in the separation tank is usually aided by addition of washwater."

Jan 1, 2018

By Hajime Miki, Mutia Dewi Yuniati, Tsuyoshi Hirajima, Keiko Sasaki

Acid mine drainage is mainly due to pyrite/arsenopyrite oxidation processes, and suppressing such processes is important issue. As a promising process it is reported that silicate ion can complex with catechol (1,2-dihydroxybenzene) and this complex is oxidized to a solid silica layer on the surface of those sulphide minerals. Detailed behavior was investigated from the result of electrochemical experiments. Results of polarization potential showed that oxidation peak can be seen only in the presence of both silicate ion and catechol addition at this peak potential and this peak can be identified as silicate-catechol complex oxidation to silica. Potentiostatic experiments indicated the dissolution kinetics of pyrite. Untreated pyrite dissolution rates were higher than pyrite treated with catechol and silica solution. To enhance the silica layer reaction on pyrite, the pyrite potential was held at 550 mV vs. SHE in catechol silica solution. This pyrite dissolution kinetics was almost the same as untreated pyrite. Potential hold followed by drying for 30 min process resulted in much lower pyrite dissolution rates. Drying is important for development of the silica layer. Analysis of this potentiostatic curve provided a way to estimate the thickness of the produced silica layer and kinetic information of treated/untreated pyrite. Untreated pyrite showed thinner initial layer thickness on the surface of pyrite (oxidized passive layer, not silica) and higher oxidative kinetics of pyrite compared with silica-coated pyrite.

Jan 1, 2014

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 K. Price, G. Wang, L. R. Moore, Y. R. Xiong, J. Gu

"Sand is a naturally occurring granular material that is a result of the physical or chemical breakdown of rocks. Raw/natural sand contains various minerals, and it is this combination of minerals that brings the value to the construction aggregate industry. However, it is the quartz component of sand that is valued in its application as industrial silica in glass, high purity quartz, foundry sand, and oil and gas fracturing. Depending on the industry, the grade requirements can be the concentration of SiO2, particle size or shape, as well as contaminants such as the heavy refractory minerals, clays, fines, and alkali metals. With the ever declining mineral feed grade, processors continue to face challenges making the industry specific concentrate grade. As such, it becomes more important to tailor make the processing reagents to fit the mineral, processing conditions, and desired quality specification. This paper focuses on the application of novel collectors towards the beneficiation of sand for each of the major industrial silica applications. INTRODUCTIONQuartz is a mineral composed of a framework of silicon and oxygen atoms. It is the second most abundant mineral in the Earth’s continental crust. There are many species of quartz, which are defined by the particle size, shape, and color. Silica sand is one of those species, which is the byproduct of the physical or chemical breakdown of quartz containing rocks or crystals. Geologist define silica sand as a silica mineral with a particle size between 0.05 and 2 mm in diameter (Zdunczyk, 2001). Silica sand has significant value to society in recreation (beach sand and toy boxes), construction aggregate (concretes and asphalt), industry (iron & steel casting, fracturing proppants, and glass), as well as specialty products such as semiconductors or silicon wafers used in electronics.The aggregate business is the dominant consumer of silica sand products. Conversely, glass making, foundries (casting material), abrasives, and fracturing proppants are the dominant applications for industrial silica sand. Not much beneficiation is required for sand products going into the construction industry, other than sizing and scrubbing to remove clay. However, the industrial silica sand applications are dependent on particle size, shape, and degree of contaminants, which sets the market value (table 1). Therefore, as the more specialty products are produced, more sophisticated techniques and chemistry need to be applied to ensure the appropriate quality is met."

Jan 1, 2018

By S. Serranti

A fast, reliable, and low cost characterization of ore minerals products, as they result from different processing actions, represents one of the most challenging targets in the mineral processing sector. Today different techniques are available according to different sampling strategies and analytical principles. In this paper, the possibilities offered by the adoption of hyperspectral imaging based sensing units working both at micro- and macro-scale are presented and discussed. According to the different phases and stages of ore minerals and products characterization, and starting from the analyses of the detected hyperspectral firms, it is thus possible to derive useful information about mineral flow stream properties and their physical-chemical attributes. This last aspect can be utilized to define innovative process mineralogy strategies and to implement on-line procedures at processing level. The present study discusses the effects related to the adoption of different hardware configurations, the utilization of different logics to perform the analysis and the selection of different algorithms according to the different characterization, inspection, and quality control actions to apply. Keywords: process mineralogy, hyperspectral imaging, NIR spectroscopy, surface mapping, textural analysis, quality control

Sep 1, 2012

By Matti Kongas, Kari Saloheimo, Antti Remes

"The paper studies the control performance of the flotation process as a function of the measurement accuracy and sampling frequency of an on-stream XRF analyzer, using a simple dynamic model. An additional aim is to assess how the economical result of a mineral flotation process depends on the quality of process control based on the on-line elemental assays.An on-stream XRF analyzer measures the concentrations of slurry lines in a continuous cycle from several process points. The control performance depends on the analytical accuracy and sampling frequency of the concentration measurement. With a long cycle time, the state of the process changes before a new measurement becomes available. With short measurement times the statistical variance of the counted X-ray pulses increases, increasing the random error in the analysis. In addition, the measurement accuracy depends on the concentration of the component to be measured from the slurry.To quantify the effect of analysis error and frequency to process control, a simple dynamic process model is created in the Matlab environment. Data from a copper flotation circuit is used as a test case. The process model comprises a first order reaction equation and the grade-recovery -relationship estimated from process data. The control was modeled using the control strategies implemented into a rule based advanced control system.The economical performance of the control was studied by calculating the overall net smelter return at various analyzer parameter combinations. The economical performance of the process declines strongly when the sampling cycle is increased. In studied case the sample measurement time did not have a significant effect on the results. The economical performance of the simulated process corresponds to an almost uncontrolled process when sampling cycles longer than 40 min are applied."

Jan 1, 2003

By Bisweswar Das, Barada Mishra, Hrushikesh Sahoo, Swagat Rath

Banded hematite jasper (BHJ) containing 45.2% Fe, 32.64% SiO2, 0.63 % Al2O3 and 1.25 % LOI is found difficult to beneficiate either by magnetic or flotation techniques due to fine intergrowth of jasper with hematite. Phase transformation by reduction roasting with activated charcoal followed by low intensity magnetic separation to achieve a suitable iron concentrate has been attempted in this study. The mineralogy of the ore and different roasted products has been studied by X-ray powder diffraction (XRD) and scanning electron microscope (SEM) to understand the reduction mechanism. The magnetite formation is observed at 850ºC while metallic iron appeared at a higher temperature. The effects of reduction variables such as reduction time (30-270 min), temperature (750-1050ºC), and reductant (1-12 %) using activated charcoal are studied. An iron concentrate with 64.65% Fe and 55.8% recovery could be obtained under optimum conditions of temperature: 850ºC, time: 1.5 h, and reductant: 6% by weight.

Jan 1, 2014

By Igor P. Solozhenkin, Peter M. Solozhenkin, Sanda Krausz

"In this work, authors will show the efficiency of computer technology and chemical programs at studying collectors for flotation of minerals of elements of platinum group (EPG). Clusters various minerals EPG (flotation reagents) are created, named us clusters minerals (reagents) as their structure corresponds to the chemical formula, and the distance between separate atoms corresponds to the known tabulated data. By molecular modeling are investigated clusters sperrylite PtAs2, stumpfilyte PtSb, sadberryte PdSb, sobolevskite PdBi, palladoarsenyte Pd2As, paolovyte Pd2Sn, rustenburgyte (Pt3Sn, Pt6Sn2) and their computer parameters (absolute rigidity, electronegativity, transfer factors of carry, charges of the atoms) are determined. Tellurides of palladium (IV, II) merenskyite PdTl2 and kotulskyte PdTe and platinum clusters are investigated: PtFe4, Pt3Fe, PtFe (Pt2Fe2), Pt2Fe (Cu) Ni. The technique of attachment of the collector (composites) to cluster atoms EPG is offered. For the first time, it is established that at linkage of flotation collectors on monodentate, bidentate and bridged to circuits with atoms clusters the minerals containing atoms As, Sb, Bi, Pb, Sn, reaction of connection with change of a degree of oxidation of these atoms and occurrence of a proton operates. It is executed virtual skirling organic compounds connections by the developed criteria from accessible libraries of a database. The principle of an estimation of interaction energy for flotation reagents with mineral clusters is offered. It is developed the prognosis of collector activity evaluation (P?AE) and his values for candidates in collectors for flotation of minerals EPG are calculated. For flotation of ores containing Pt and Pd minerals, a number of reagents, including compounds on basis P (III), for innovational technology of Pt, Pd mineral flotation are recommended. Key words: flotation, minerals, flotation reagents on the basis of phosphorus (III), molecular modelling, chemical programs, program ????? , electronic energy."

Jan 1, 2014

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 Brian Hart, Stamen Dimov

"In refractory ores, a substantial part of the gold content may be present as a sub-microscopic component within the mineral matrix of the various carriers. This type of gold may be present as finely disseminated colloidal size gold particles (<0.5µm) or as a solid solution within the sulphide mineral matrix. Such ores are not amenable to gold recovery by direct cyanidation. In order to liberate the sub-microscopic gold, the ore has to be oxidized before being subjected to gold cyanidation and extraction. Autoclave pressure oxidation (AC POX) of the sulphide ore and subsequent cyanidation is a common technology used to liberate the gold in such refractory ores. The additional presence of active carbonaceous matter in such ores (double refractory ores) represents another major obstacle for efficient gold recovery during the process of pressure oxidation and cyanidation. This carbonaceous matter (c-matter) can adversely affect the gold recovery due to its ability to adsorb, or pre-grob gold from the cyanide solution. Advanced micro-beam analytical techniques such as Dynamic Secondary Ion Mass Spectrometry (D-SIMS) and Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) have become powerful tools for characterization of different forms and carriers of gold for the needs of the mineral processing industry. Major advantages of these techniques are related to their ability to analyze individual mineral particles and provide quantitative analysis with detection limits in the low ppm/ppb concentration range. This paper describes various micro-beam techniques and procedures implemented at Surface Science Western (SSW) for quantification and characterization of the sub-microscopic gold and the preg-robbed surface gold as part of full gold deportment studies in feeds and process stream products."

Jan 1, 2014

By Carolina Achiardi, Álvaro Videla

"In pre-design a flotation plant copper sulphide is useful to apply a simplified methodology of economic analysis that relates the size of the grinding product (P80) with the throughput and their effect on copper grade and recovery of copper in the final concentrate of a flotation circuit. With this objective, this methodology covers the following analysis, perform by evaluation of five sizes grinding products (P80): 120, 150, 180, 210 and 240 microns. • Flotation testwork (rougher kinetic, open and closed cycle test) has been done to determinate the optimum operating conditions and to estimate the maximum recovery of copper in the concentrate, using Klimpell model • Flotation plant design assumes a conminution product obtained from a 25,000 HP ball mill • Metallurgical balance is performed for the circuit based on flotation testwork • Economic evaluation by calculating capital expenditure (CAPEX), operating expenditure (OPEX) and sales revenue, to determine NPV is performed and relates to the NPV. An optimum grind size is then obtained based on cash flow. The results shows a grinding product size that optimizes flotation and allows a higher NPV and INPV over other alternatives."

Jan 1, 2014