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By J. Drzymala

Ores and raw materials are subjected to mineral processing operations to increase the content of their useful components. Upgrading of these materials can proceed with different selectivity and therefore, there is a need to know and monitor the separation results of the process. The separation results can be evaluated using tables and graphs called upgrading curves. The course of lines in the upgrading curves is usually complex and depends on the graph type and process parameters. The Halbich grade vs. recovery plot is frequently used because is practical and it indicates several characteristic features of separation results. Separations by means of flotation of several different shale, dolomite and sandstone copper ores were performed along with determination of their mineral composition, copper content, liberation degree, and the maximum theoretical copper content in the first concentrate. These data, plotted as the Halbich upgrading curves, allowed to find other characteristic points such as practical maximum copper content in the first concentrate, maximum curvature coexisting with the liberation degree, maximum recovery of ore valuable components, and the slope the recovery-grade line at high recoveries as a measure of liberation. Correlations between theoretical and practical maximum copper contents in the first concentrate as well liberation degree and maximum curvature were also presented. They show that the ore type significantly influences the shape of the Halbich curve and its characteristic points.

Sep 1, 2012

By Rod Hocking, Nenad Djordjevic, Randolph Pax

"Semi Autogenous (SAG) mills exhibit complex interactions between the competing processes occurring inside them. Traditional practice is to measure the operation of the SAG mill at an operating point in terms of its load, power draw, steel load, ore throughput rate, water addition rate and more recently the feed size distribution. However significant departures of operating conditions can occur due to changes, for example, in ore hardness, the quest for higher throughputs and mill internal geometry.Fundamental to SAG mill operation are the internal processes that ensure that a given ore throughput and discharge grind size are obtained and maintained. These processes can be measured using non-contact acoustic emissions from the SAG mills which utilise the information rich noise that is generated by the grinding, flow and charge movement inside a mill.Non-contact acoustic in-mill measurements can be used for the validation of discrete element modelling (DEM). The approach being reported in this paper is to model the individual physical processes and then to simulated the assemblage of a physical mill."

Jan 1, 2003

By Y. Q. He

The methodology of active pulsing air separation is a new method for dry material classification. Especially, it is suitable to electronic scraps disposal and re-utilization. By studying the difference of drag coefficients of the particles moving through areas of varying Reynolds numbers, and considering the extra-mass forces acting on the particles in the active pulsing air field, models of the dynamic motion which particles follow were developed. A computer simulation was prepared that showed the traces of particles with different densities and/or diameters, but similar aerodynamic characteristics, as they moved through the turbulent flow, to modify and define the parameters of the models. The simulation was found to predict the observed results with artificial tracing spheres being separated by the laboratory equipment. The separation performance, as being affected by the particles, nature, the air velocity, the pulsing frequency and the air pattern, is discussed. In general, lower density particles are more responsive to variations in airflow velocity. In addition, an industrial scale active pulsing air separator was designed, and it provides a new and efficient method for resource re-utilization in China.

Jan 1, 2014

By Hamid-Reza Manouchehri

"Sustainability calls for maintenance, rational use and enhancement of natural resources as well as balance consideration of ecology, economy, and social justice. The challenges in mining industry call for a sustained global effort using the leverage of available technologies and emerging new technologies. The industry uses significant amount of energy with the highest portion in comminution. To conserve energy, attempts have been made to improve the efficiency of the conventional crushing and grinding equipment. Nevertheless, the new and energy efficient comminution technologies are favorable through a longer term strategy. Since crushers are more energy efficient than mills, it is logic to conduct part of milling, in the crushing stage. After years of research and development, Sandvik introduces a new crushing technology, VibroconeTM, to change traditional crushing concepts. The new crushing device is able to crush and grind particles with a higher reduction ratio, more than two fold, than that of conventional crushers. By implementation of the new technology, a suitable feed size for milling can be provided to conserve energy as well as media and liner consumption, to reduce milling circulating load or increase mill capacity. There are other benefits associated with this machine, one of them being providing a higher surface area. This paper discusses the performance of the machine and its applications for comminuting different ores."

Jan 1, 2014

By A. Saramak

"The paper focuses on problems of atmospheric pollution by the dusts, produced during the course of crushing and grinding processes, and the main objective of investigative programme is an assessment of emission of particulate pollutants for following crushing devices operated in plant scale: impactors, cone and jaw crushers. All crushers operate in aggregate production plants in Poland. In the first stage of investigations there were determined dust emission levels and supporting characteristics for all crushers under investigation. Then there were introduced indices that allow for comparative analysis in terms of dust emission, for devices with different energy consumptions and comminution ratio. It appeared that crushers with high the overall dust emission do not always achieved unfavorable dust emission per comminution ratio or energy consumption. The introduced indices proved their usefulness, because they helped to carry out a comparative analysis among crushers, operating under different technological conditions. It is also easier to assess environmental impact of individual crushing devices, under analysis. Results of investigations also show that environmental impact of different types of crushers is diverse and it is difficult to compare dust emissions of various types of crushers without taking into account technological aspects (like throughput, comminution ratio, energy consumption, and others) of their operations.INTRODUCTION Mineral processing of raw material is a complex process, involving in general operations of size reductions and separation. Depending on the type of specific raw material, the technological circuit may include operations of comminution and size classification. This is a typical circuit for aggregate production. In ore treatment industry the process in much more complicated and include also a metallurgical treatment of ore concentrate – the final product from processing plant stage.In general, regardless the type of raw material, operations of size reduction are present in each technological circuit of mineral processing. Operations of crushing and grinding are an integral part of processing technology, because they play a crucial role in effective treatment of mineral raw materials (Gawenda 2013). Their duty is to liberate the useful minerals from the gangue in ore treatment industry, or to produce the material with the required particle size in case of aggregate processing. Crushing and grinding operations are of a high negative impact on environment and humans. They consume great amounts of energy, what indirectly contributes to higher emission of carbon dioxide CO2. Apart from energy, crushing and grinding device consume significant amount of steel and other metals and alloys due to high wear of working parts and grinding media. This is also of negative environmental impact due to emissions of additional amounts of CO2 in production of steel and other metals required as spare parts for comminution devices."

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 Vincent C. Smith, Agit Singh, Bernard Muller

The control of minerals processing plants is by no means trivial. In order to address some of the difficulties, it was decided to develop and test a model predictive controller (MPC) for a milling circuit. A milling simulator was written to test the MPC controller. Due to the large number of tuning parameters in a controller of this type, an optimising algorithm was written that automatically tunes the controller. Good, robust control was obtained when the controller was tuned using this algorithm. The controller was tested for various scenarios that are often encountered in the minerals processing industry. When problems were encountered, the MPC algorithm was specially adapted to accommodate for these difficulties. Control was further improved by using feedforward control as well as quadratic programming. The movement of the manipulated variables was reduced by using a region of uncertainty that allows the controlled variable to vary within a specified region around the setpoint. Integrators were handled by adapting the algorithm slightly and adding an optional integral error portion in the MPC controller. The performance of the enhanced MPC controller was compared to PI controllers on both the simulator and a commercial plant. The MPC controller showed faster responses with less interaction in both cases.

Jan 1, 2003

By L. Stamenov, H. Bouzahzah, S. Gaydardzhiev, D. Naumov

"The Chelopech epithermal arsenic bearing high-sulphidation, copper-gold deposit located in Bulgaria is often referred as the richest European gold deposit currently under exploitation. Key points from the flotation circuit of the processing plant have been sampled and selected physicochemical parameters measured. Plant survey has followed with selected samples being submitted to chemical and mineral liberation analysis (MLA). Quantitative analysis has enabled to link the flotation response of the main copper bearing minerals with the physiochemical parameters (Eh, DO, EDTA extractable Cu and Fe) being measured. Data from mineral liberation analysis have highlighted an important process-relevant information explaining the variable floatability in the various granulometric classes.The low chalcopyrite recovery could be linked to the non-sufficient amount of dissolved oxygen measured in the copper selective flotation circuit. Given the finely-disseminated copper bearing minerals, the observed copper losses inside the flotation could be also explained by the insufficient degree of liberation of the mineral grains. Suggestions for improvement in metallurgical recovery are therefore proposed.INTRODUCTIONThe Chelopech deposit is a high sulphidation (HS) volcanic-hosted epithermal gold-copper one (Bonev et al., 2002; Kouzmanov et al, 2009; Strashimirov, et al. 2002). It is considered as one of the largest and economically most important ore deposits in Bulgaria, and often is referred to Europe’s largest currently mined gold resource. It is located in the Srednogorie zone which falls within the central sector of the extensive Tethyan–Eurasian copper belt formed during Mesozoic–Cenozoic time along the southern margin of Eurasia. The Srednogorie zone has the features of a subduction-related, Late Cretaceous island arc, with development of a calk-alkaline to sub-alkaline volcano-plutonic magmatism and associated hydrothermal ore deposits (Bonev et al., 2002).Ore mineralisation occurs as veins, mineralised breccia, and massive sulphide replacements and disseminations. Three mineralisation stages have been identified at Chelopech deposit. An early pyrite–marcasite mineralisation (stage I), characterised by disseminated to massive pyrite followed and partly brecciated by enargite– luzonite and tennantite–chalcopyrite–bornite (stage II) mineralisation. The gold is met in ores belonging to the stage II. Sphalerite and galena veins characterise stage III, best developed below and adjacent to the pyrite–enargite– chalcopyrite ore bodies. Advanced argillic altered volcanoclastic rocks commonly host this mineralisation (Chambefort and R. Moritz, 2014)."

Jan 1, 2018

By Brian Hart, Liuyin Xia, Staman Dimov

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

Jan 1, 2014

By Arkady Senchenko

The paper deals with the problem of refractory gold-containing material processing. It is observed that all traditional methods for liberation of fine gold from this type of products are characterized by a number of essential disadvantages, where the main ones are ? considerable expenses for ore processing and big environmental impact. As an alternative to the existing methods there is considered a gold liberation method, which is based on the combination of ultra fine grinding process with the consequent atmospheric oxidation. The theoretical justification of atmospheric oxidation was carried out, in the result of this the mechanism and the degree of sulphide minerals? oxidation was found out, the dependence of gold dissolution speed on the slurry content in liquid phase produced by grinding and oxidation was identified. The experimental data and results of pilot-plant testing are given and the most effective grinding and atmospheric oxidation mode is selected on this basis. The performed complex of research works allowed us to use the provided technology at the gold processing plant having capacity of 8 mln. tons of ore per year. The questions, problems, advantages and disadvantages of atmospheric oxidation technology for refractory gold-containing concentrates are considered in this paper. Keywords: refractory gold-containing material processing, gold liberation method, cyanidation

Sep 1, 2012

By V. G. Minenko, V. A. Chanturiya, A. L. Samusev

Eudialyte is one of perspective resources of zirconium and other rare earth elements (REEs). Large reserves of eudialyte concentrated in the Murmansk region of the Russian Federation. Usually, technologies of REE treatment include the decomposition of eudialyte concentrate in different acidic, extraction and utilization of all components. The main problems in the leaching of eudialyte include are: the formation of an unfiltered silicon-containing gel; low recovery of REE; difficulty extraction of metals from the productive solution; high aggressiveness of the reagents. One of the promising trends of intensification of the processing of hard-to-degrease rare metal raw materials is the use of energy methods for affecting mineral suspensions. These methods make it possible to increase the efficiency of break up fine-dispersed mineral complexes and extracting micro- and nanoparticles of a valuable component in subsequent deep processing. The purpose of this work is to investigate the effect of energy impacts on the nitric acid leaching of eudialyte concentrate. Experimental studies were carried out in a developed laboratory facility that makes it possible to evaluate the effect of electrochemical, ultrasonic and combined effects on the leaching of zirconium and REE from eudialyte concentrate. The studies carried out on the samples of eudialyte concentrate with the size class of -0.315 + 0.063 mm showed that the use of electrochemical and acoustic effects increases the extraction of ZrO2 in the production solution in 1.6 - 2.5 times, REE in 1.3 - 2.2 times, respectively. An analysis of the microstructure and phase composition of the surface of the eudialyte concentrate showed that the intensification of the leaching process is due to surface cleaning from the silicon-containing gel, as well as the opening of capillary channels and microcracks, which accelerates mass-transfer processes. The results obtained open wide opportunities for creation of modern and effective technology of processing of eudialyte concentrate, producing high-quality zirconium products and REE.

Jan 1, 2018

In this study, the effect of different regrinding conditions on the depression of fine pyrite at the cleaner stage was investigated. The regrinding condition was manipulated by different grinding media (stainless steel and mild steel). It was found that, after regrinding with mild steel grinding media, the flotation recovery of pyrite is much lower than with stainless steel grinding media, and it is more difficult to restore by adding more collector. This means, regrinding with mild steel grinding media may depress the pyrite flotation more strongly. The copper activation of pyrite during regrinding was also studied. It was found, that the mild steel grinding media is more beneficial to copper activation than stainless steel media. Additionally, the analysis of pyrite recovery based on the particle size indicated, that the fine particles are more susceptible to different grinding environments than intermediate and coarse particles and therefore are more easily depressed with a much lower flotation recovery.

Sep 1, 2012

By P. Somasundaran, G. Anastassakis, Z. Pan, D. R. Nagaraj

Gums are often used as depressants for talceous gangue minerals in the flotation of nickel and platinum bearing ores. However, the mechanisms of gum adsorption on talc are not clearly established. In this work, adsorption of guar gum at the talc-solution interface is investigated using spectroscopic and allied techniques. Guar gum adsorption on talc is not affected significantly by changes in solution conditions such as pH and ionic strength. Electrokinetic studies showed that guar gum decreased the negative zeta potential of talc but did not reverse the charge. Fluorescence spectroscopy studies conducted to investigate the role of hydrophobic bonding using pyrene and dansyl probes showed no evidence of the formation of hydrophobic domains at talc-aqueous interface. Urea, a hydrogen bond breaker, reduced the adsorption of guar on talc to the same extent as that for guar/alumina system, in which hydrogen bond plays an important role. All of the above results suggest that one of the main driving forces for guar adsorption on talc is hydrogen bonding rather than electrostatic or hydrophobic force.

Jan 1, 2003

By K. V. Fedotov, E. V. Zelinskaya, O. V. Ulanova

"Mining enterprises, in particular, those on the territory of the Siberian platform, produce large amounts of pumped water, which cannot be recycled because of its high mineralization and, thus, is discharged as liquid waste either back into the ground or onto the surface. However, groundwater is often a valuable raw material and a source of useful chemical substances. Brines are unique groundwaters. In the current environmental and economic situation, the huge loss of natural raw materials and their deliberate conversion into wastes is unaffordable. The exploration of non-traditional sources of minerals such as the hydromineral resources (including pit water) is a matter of rational nature management. The industrial value of brines of the Siberian platform is due to the high contents of rare alkali and earth alkaline elements (lithium, rubidium, cesium, strontium, bromine, etc.). The absolute concentrations of these elements in brines are tens of times higher than the lower limits of the mining cut-off. The long-term data analysis was performed to estimate the environmental impact of liquid waste from two mining enterprises, namely, Korshunovskii (Irkutsk region) and Udachnaya (Southern Yakutia). The study was focused on the prospects of hydromineral resources as non-traditional sources of valuable elements and the exploration of technological processes for the selective extraction of rare alkali and earth alkaline metals from natural multi-component brines aimed at decreasing their negative environmental impact. The environmental and economic efficiency was proved for the processing of complex brines and the integrated selective extraction of rare earth metals from sodium chloride brines of the Korshunovskii plant and calcium chloride brines of the Udachnaya plant based on the ion exchange sorption, eluent chromatography, flotation, crystallization, and freezing techniques. The basic technological schemes were developed for the metal extraction from pit water and brines.INTRODUCTION In the Irkutsk region (the Angara–Lena artesian basin) and in Yakutia (the Olenek and Tunguska artesian basins), several mineral deposits are developed and, incidentally, aquifers bearing brines of different types are opened, which are eventually converted into liquid production waste (Rusetskaya et al., 1994) This raises the issue of the burial or utilization of brines since their use within the water circulation is impracticable under the existing technological conditions while their discharge into the surface watercourse is unacceptable because of the harmful environmental impact."

Jan 1, 2018

By M. Maldonado

A flotation bank is a serial arrangement of cells. How to optimally operate a bank remains a challenge. This article reviews three reported strategies: air profiling, mass-pull (froth velocity) profiling and Peak Air Recovery (PAR) profiling. These are all ways of manipulating the recovery profile down a bank, which may be the property being exploited. Mathematical analysis has shown that a flat cell-by-cell recovery profile maximizes the separation of two floatable minerals for a given target bank recovery when the relative floatability is constant down the bank. Available bank survey data are analyzed with respect to recovery profiling. Possible variations on recovery profile to minimize entrainment are discussed.

Sep 1, 2012

By Michel Brissette, Shaheer Sanuri, Veroljub Mihajlovic

"The main purpose of geometallurgy is to improve the mine planning by mapping hardness and throughput into the mine block model using geostatistics to eliminate the large production fluctuations caused by the ore hardness variability coming from different parts of the pit. However, not all grinding testwork available commercially can be applied to geometallurgy because of large amount of sample required and the associated cost per test. Geometallurgy is now being used in designing grinding mill but as the mining project progress, the accuracy of engineering must improve from 30-35% during the scoping study to 10-15% at the bankable feasibility stage and less than 5% for Engineering Procurement and Construction Management. For SAG milling, the SAG Variability Test (SVT) is an abbreviated version of the standard SAGDesign test developed for this geometallurgical need. The same amount of ore than the original test is ground for three cycles into an open batch SAG test and then the SAG pinion energy is predicted to the standard end point of 80% passing 1.7 mm. For ball milling, a Bond Variability Test (BVT) was also developed using the SAG ground ore from the SVT. The Bond ball mill grindability (Gpb), corresponding to the average of the net grams per revolution from the last three cycles of the Bond test, is also predicted from the third cycle. The relative error for both the predicted SAG ore hardness (WSVT) and Bond Work Index on SAG Variability ground ore (Sv-BVI), in kWh/t, averaged 5.5% and 3.8% respectively compared to the SAGDesign testwork values and are within 7% and 10% respectively from plant benchmark and within 7% from the samples sent to all partner laboratories. Both tests can be continued to measure the true hardness necessary for mill sizing. This article discusses the development of these two new tests, SVT and BVT, their potential use and accuracies in any geometallurgical program."

Jan 1, 2014

By Anuttam Patra, Romain Bordes, Andreas Fredriksson, Tommy Karlkvist, Krister Holmberg, Kota Hanumantha Rao

The present investigation aims to develop and distinguish mineral specific reagents with two functional groups for use in flotation of calcium containing minerals. For this purpose, a series of dicarboxylate-based surfactants with varying length between the carboxylate groups (one, two or three methylene groups) were synthesized. As reference, a surfactant with the same alkyl chain length but with only one carboxylate group in the polar part was synthesized. The adsorption behavior of these new reagents on pure apatite and calcite mineral surfaces was studied using Hallimond tube flotation, FTIR and ? potential measurements. The relation between the adsorption behavior of a given surfactant on a specific mineral surface and its molecular structure over a range of concentration and pH values, as well as the region of maximum recovery were established. It was found that one of the reagents, with a specific distance between the carboxylate groups, was much more selective for a particular mineral surface than the other homologues synthesized. This selective adsorption of a given surfactant to a particular mineral surface relative to other mineral surfaces as evidenced in flotation studies is substantiated by ? potential and infra-red spectroscopy data.

Jan 1, 2014

By Luís Marcelo Tavares, Juliana Segura

Comminution is one of the most energy consuming stages in a mineral processing plant. This consumption is not only related to the power supplied to equipment, but also to the indirect or embodied energy, mainly associated to materials that are worn during operation, including grinding media and liners. Until recently, preparation of iron ores in Brazil did not use comminution intensively, given that plants mainly produced sinter feed, natural pellet fines, besides lump ore. However, with decreasing ore grades, size reduction now occupies a centre stage in nearly all new plants. Technologies used up to date for processing low-grade iron ores in Brazil, in particular itabirites, have consisted of three or four stages of crushing followed by ball milling. A number of new plants are either being built or are currently being designed that will process the same type of ore, so that engineers are investigating alternative comminution routes. The paper analyses comparatively four comminution routes for processing a particular itabirite ore, many of which using technologies and layouts that have not yet been used in such application. Using data from bench scale and/or pilot-plant tests, the different routes are compared on the basis of sustainability principles in accordance to the Brazilian energy matrix, which is quite particular. It is concluded that if the sustainability criterion is used, then the optimal route would correspond to a circuit that uses HPGR technology with truncated feed followed by ball milling. Given the particular case of itabirite iron ores and specially to the one in the present work and the source of Brazilian energy, it is evident that indirect energy expenditure in comminution plays a significant role in greenhouse gas emissions when compared to direct energy, being the reason for the great attractiveness of HPGR technology. Evidently that these will have to be balanced against CAPEX, OPEX, NPV and other qualitative criteria, which can certainly lead to a different optimal circuit.

Jan 1, 2014

By Erico Tabosa, Kym Runge, Peter Holtham

"The distribution of turbulence in an industrial scale mechanical flotation cell and its effect on flotation kinetics was studied using a fully instrumented 3m³ cell. The cell was operated at a copper concentrator in Australia with different combinations of airflow rates, impeller speeds and sizes and cell aspect ratio providing a wide range of hydrodynamic conditions. An analysis of the overall flotation cell performance showed that the overall copper recoveries were very similar for the conditions tested. However, by decoupling pulp effects from froth effects it was possible to evaluate whether the changes made affected the pulp zone and/or froth zone responses. The analysis showed that the overall recovery has the potential to be up to 7% higher, if not limited by froth recovery. The cell hydrodynamics were characterised by the overall energy dissipation rate and, to understand the distribution of turbulence within the cell, localised measurements were made using a piezoelectric vibration sensor. By comparing the metallurgical performance of the cell with the different hydrodynamic conditions it was found that the collection zone flotation rate constant was not directly related to overall energy dissipation, as is commonly observed at laboratory scale, where energy is usually only changed by varying impeller speed. In this study, energy dissipation rate was varied using not only impeller speed, but also the size of the impeller and the cell aspect ratio. In these circumstances, the best correlation was found to be between the collection zone flotation rate constant and the distribution of turbulence, i.e. the size of the turbulent zone."

Jan 1, 2014

By Xiao Jian Li, Dai Xiong Chen, Jian Wen Yang

In one kind of lead and zinc bearing polymetallic ore containing secondary copper, the characteristic of low sulfur, high zinc, and particularly the existing of secondary copper minerals can lead to lead concentrate with high content of zinc because the dissociation of Cu2+ in the grinding process may have an activation influence on sphalerite. Considering its process mineralogy analysis, a new process of seperation of lead and zinc has been put forward. The experiments focused on the analysis of the advantages and disadvantages of the inhibition effect of traditional adjustment reagent + zinc sulfate on activated sphalerite compared with new organic inhibitor, polysaccharide xanthate. According to the numerical calculation and test results, a reagent system of polysaccharide xanthates is developed, which has a good inhibition effect on Cu2+ activated zinc minerals, achieving high-efficiency separation of lead and zinc. A new reagent system and flotation process was developed under optimal conditions. Under the condition of the run-of-mine ore containing 2.37% Pb and 12.48% Zn, lead of 67.69% grade and lead concentrate with the recovery rate of 86.06%, zinc of 60.32% grade and zinc concentrate with the recovery rate of 96.15% were achieved.

Jan 1, 2014