Search Documents

By Z. Hu

A complex polymetallic sulfide ore in Yunnan, China, has various valuable minerals, which are Chalcopyrite, Galena, Pyrite, Gold, Silver, and Magnetite. A reasonable new flowsheet with a bulk flotation and a flotation separation of sulfide minerals that are Chalcopyrite, Galena, and Pyrite was carried out at first stage. After that tailings were treated by low intensity magnetic separation to achieve magnetite concentrate. A high Pb concentrate assaying 60.00 percent Pb at total recovery of 75.71 percent with 40.50 g/t Au and 1390.00 g/t Ag, a final high Cu concentrate assaying 24.45 percent Cu at high recovery of 92.03 percent and a magnetite concentrate assaying 60.78 percent Fe at recovery of 33.61 percent with 18.45g/t Au and 234.99 g/t Ag, are obtained. The total recovery of Gold and Silver in Pb concentrate and Cu concentrate reached 71.63 percent and 67.32 percent, respectively. It is shown, that this new flowsheet could realize efficient recovery for all of the valuable minerals in the ore and is easy to be industrialized. Keywords: bulk flotation, magnetic separation, polymetallic sulfide ore, depressant

Sep 1, 2012

By T. Khonthu

The purpose of this investigation was to evaluate the relationship between different milling procedures, viz. a ball mill and an IsaMill respectively, and the flotation performance of the different mill products. Two ores were used, viz. a base metal sulphide (BMS) and a platinum group mineral (PGM) UG2 ore. Flotation was used as a diagnostic to investigate whether the different milling procedures may have different effects of the floatability of the particles. The present study is part of a research programme investigating this question using a wide range of comminutiondevices and procedures. Similar particle size fractions from the different milling procedures were used in the flotation tests. The particles were characterized in terms of particle size distribution, morphology (using scanning electron microscopy and image analysis software) and rheology tests. The results have shown that in general when comparing similar feeds to flotation in terms of equivalent particle size distributions as indicated by the d80 value, the ball mill generally yielded better recoveries and grades in the case of the BMS and lower chromite recoveries in the case of the UG2 ore compared to the IsaMill. No significant differences were observed in the morphological or rheological characteristics of the particles subjected to the different milling procedures. Although the results appear to indicate that IsaMilling is less advantageous than ball milling in terms of the flotation performance for the two ores studied it should be emphasized that these results do not take into account the relative advantage which IsaMilling has over ball milling in terms of direct and indirect energy consumption and GHG emissions nor, most importantly, does it consider the platinum group element recoveries in the case of the UG2 which may have increased significantly as a result of the finer grind which the IsaMill produces after 4 passes compared to the ball mill after 64 min. Such results which will be reported is due course may show that the greater liberation expected after IsaMilling of the PGMs outweighs any disadvantages indicated in this study.

Sep 1, 2012

Poor floatability of fine particles is known to be the main cause of the low recovery of ilmenite in Panzhihua, which is the largest titanium mine of China. To get an optimum ilmenite recovery, selective flocculation, and flotation of fine ilmenite was investigated through flotation tests, particle size analysis, zeta potential tests and scanning electron microscopy. The results indicate that carboxymethyl cellulose (CMC) shows flocculation effect for both ilmenite and titanaugite without selectivity, while selective flocculation could be realized by the combination of water glass and CMC. It is because that competitive adsorption would take place on these two kinds of mineral when water glass and CMC are used together. On the surface of ilmenite, the adsorption ability of CMC is stronger than that of water glass, so that CMC can absorb to the same extent irrespective of the presence of a pre-adsorbed layer of water glass and ilmenite particles is flocculated by CMC. The same cannot be said of the titanaugite phase as water glass strongly adsorbs onto the titanaugite, and the adsorption of CMC is hindered. Therefore, the titanaugite particles keep dispersion. Furthermore, the flotation of fine ilmenite particles is feasible as the ilmenite floccules could react with sodium oleate. In the flotation separation of Panzhihua ilmenite ore, the recovery of TiO2 increased from 52.63% to 68.28% by selective flotation. Keywords: ilmenite, flotation, selective flocculation, adsorption

Sep 1, 2012

By M. V. Sowmya

Batch biosorption experiments were carried out for the bio-remediation of Cr (VI) ions from aqueous solutions using Serratia marcescens, a Gram negative, heterotroph and Gram positive bacterial isolates from a chromite mine. The influence of various experimental parameters such as contact time, pH, concentration of Cr (VI) ions and amount of biomass was evaluated with respect to the uptake of Cr (VI). The bio-sorption of Cr (VI) was found to be quite rapid and the percentage biosortion was found to increase with increase in the equilibrium chromium concentration. The free energy of biosorption of Cr (VI) was estimated to be in the range of -23 to -25 kJ/mol for the chosen bacteria. The uptake of chromium by the bacteria was confirmed by EDX and FTIR spectroscopy. As a follow up of this study, bacterial strains resistant to hexavalent chromium were isolated from a chromite mine in Karnataka, India and identified as Arthrobacter sp., Micrococcus sp. and Exiguobacterium sp. using 16s rRNA sequencing. The efficacy of the bacterial isolates for Cr (VI) uptake was assessed and over 90% bioremoval could be achieved for Serratia marcescens and Micrococcus sp. isolate. Possible mechanisms of chromium uptake by the microorganism are discussed. Keywords: bioremediation, hexavalent chromium, biosorption, bioreduction

Sep 1, 2012

By D. Moradkhani

The heap leaching of oxide copper ores with copper cathode recovery by solvent extraction and electrowinning is now well established as a low-cost method of copper recovery. The main purpose of this study was to extract copper from the copper low-grade oxide ore of Chodarchaei mine using column leaching. The copper oxide ore contained 1.1% Cu and 1.75% Fe. The mineralogical analysis indicated the malachite (Cu2(OH)2CO3) was mainly composed of oxidized phases. The sulfuric acid leaching experiments were performed under the laboratory conditions. The influence of several parameters on the course of the reaction such as particle size, acid concentration, flow rate, and time was examined. The optimum collective extraction of copper and iron was obtained at a particle size of +10-15 mm for a leaching duration of 3 days with sulfuric acid concentration of 100 gpl and using a flow rate of 2.5 cc/min. Under these conditions, the recovery of copper and iron were 98.54% and 41.99%, respectively. Keywords: column leaching, copper, iron, working diagram.

Sep 1, 2012

By V. Tsyplakov

This article reviews factors of preg-robbing effect, occurring in the course of pressure oxidation of ore and concentrates, containing chloride compounds and so-called 'organic carbon'. The article also summarizes the main results of the studies and testwork conducted to overcome this effect. The following efficient preg-robbing mitigation methods have been noted: higher temperature of pressure oxidation process, preliminary removal of natural carbonaceous material from concentrate, chloride removal prior to concentrate pressure oxidation, and addition of water-soluble organic blanking agents, which suppress the adsorption activity of the native ore adsorbents. Keywords: preg-robbing, double-refractory gold concentrates, pyrite, arsenopyrite, blanking agents, pressure oxidation, autoclave leaching

Sep 1, 2012

By V. K. Gupta

Selection of mill size for reducing a feed material of a given size to the desired product size is generally based on the specific energy estimate obtained from Bond test. Over the last thirty years or so, an attempt has been made to develop a more accurate and powerful alternative approach based on the characterization of the particle breakage kinetics and material transport through the mill over a range of operating conditions of interest and correlating the degree of size reduction achieved with the net specific energy input to the mill. Particle breakage kinetics are described in terms of the specific grinding rate and breakage distribution parameters for the individual size fractions. Precise estimates of these parameters and the net energy input to the test ball mill (a laboratory or pilot scale mill) are important for development of desired energy-size correlations. In this context, three tasks are important: (a) preparation of the feed charge, (b) design of batch grinding experiments and (c) computational technique used for estimation of the breakage rate and breakage distribution parameters. This paper highlights several aspects of these three tasks that have been overlooked by researchers working in this field, and describes a more appropriate approach for estimation of model parameters and specific energy input. Several examples are included based on the data available in the literature and those generated in our laboratories to illustrate important points.

Sep 1, 2012

By M. Vulkov

The paper is focused on the optimal selection of grinding medium for a drum mill. The decision-making is based on the fuzzy multiple attribute approach. One way to optimize the grinding process in a tumbling mill is associated with the development and testing a new shape of grinding body. Family of new grinding bodies ? spheroidal tetrahedrons (tetraballpebs) has been manufactured. Two types of spheroidal tetrahedrons and a classical ball (sphere) with one and the same weight are compared. A fuzzy entropy method to calculate the weight of the attributes is suggested. A grinding body which is the best approximation to the fuzzy formulated technological conditions is selected. Keywords: grinding, spheroidal tetrahedrons (tetraballpebs), balls, fuzzy sets

Sep 1, 2012

By Smuts. E. M.

This paper describes a methodology used to develop a numerical model for the study of particulate suspension rheology. Initially, Computational Fluid Dynamics (CFD) models of different rheometer geometries were tested with both a Newtonian fluid (water), and a non-Newtonian Herschel-Bulkley slurry. Rheograms were reproduced from these models and compared to experimental values. Once a single-phase model had been validated, a coupled model combining CFD and the Discrete Element Method (DEM) was created. Two open source software packages were chosen. CFD is implemented using Open FOAM®, and DEM using LIGGGHTS. These two different codes were coupled via another program called CFDEM. This coupled model is currently capable of modeling spherical particles in a suspending liquid. DLVO forces have been included in some models to account for inter-particle forces due to the surface charge on the particles. The coupled model is currently being validated. Preliminary results show good qualitative behavior of the model. Keywords: rheology, cfd, dem, suspensions, modeling

Sep 1, 2012

By B. K. Saikia

A preliminary attempt has been made to study the particle size distribution (PSD) of minerals in one of the industrially important pulverized Indian coal sample using computer-controlled scanning electron microscopy (CCSEM). The results show that clay minerals, quartz, pyrite, and pyrrhotite form the bulk of the mineral matter. Minor minerals, such as calcite, dolomite, ankerite, barite, oxidized pyrrhotite, and gypsum are also observed in the coal sample. The PSD of the included minerals is generally observed to be finer than that of the excluded ones in the coal. Thus, the coal rich in included minerals has more small mineral particles, which may affect its reactivity. The proportion of included to excluded is found to be higher in major cases. Si is found to be mostly occurred as quartz and clay minerals, while Al mostly occurs as silicate minerals. Fe is primarily present as iron sulfides, iron oxide, and Fe-Al-silicate. S is partitioned into iron sulfides and gypsum. Most Ca occurs as carbonates and gypsum, with a minor fraction associated with clay minerals. Mg is found to be mainly present as dolomite and clay minerals, with a very minor fraction present as ankerite. The majority of alkali elements are associated with aluminosilicates. P is mostly associated with kaolinite and/or present as more complex compounds containing Al, Si, and other elements as apatite are found to be absent in the coal studied. Ti is mainly present as rutile and kaolinite. The geo-chemical association of the trace elements has also been discussed. Keywords: minerals, Assam coals, Indian coals, CCSEM study

Sep 1, 2012

By H. G. Hedlund

Tailings in Mining Industry can be handled in different ways. Today tailings disposal is in focus by projecting new plants as well as treating and handling of old Tailings dams.The trend today is to process minerals, detoxify the Tailings and place them as dry surface Deposition or Underground Backfill. This paper will briefly present five different Mining plants in North and Central America, where Tailings have to be dewatered for dry depositing. The Metso-Sala VPA is a filter especially developed for dewatering and drying of Mineral Concentrate and Mineral Tailings. Keywords: tailings disposal, dewatering, drying, mineral tailings

Sep 1, 2012

By H. Breuer

Mineral processing is characterized by a constant adaptation to changing raw materials and market conditions. It is the link between the mined raw material and a marketable product. As a lot of high grade reserves are exploited, a steady deterioration of raw material quality can be observed. At the same time, the customers´ requirements for product purity and consistent quality increase. Indian iron ores are characteristically friable in nature that results in generation of sizeable quantity of fines (0-10mm) every year during various stages of mining and processing in the country with grade varying from 50-60% Fe(T) and are high in silica/alumina (Al2O3 5-8%). The fines generated cannot be directly used for iron making (blast furnace/DRI units) in the country due its physical and chemical properties; therefore, large portion of it gets exported or dumped. Value addition to iron ore fines through various activities such as beneficiation & palletization is the need of the hour, which will not only be economically beneficial to the mining sector in the long run but also generate value addition & employment opportunities. Incentives may be given for adopting latest technologies for direct use of fines in iron making by agglomeration of fines in the form of Pellets and Sinters, as fines forms considerable part of iron ore resources. Due to selective mining, although the iron content of the ore is high but the alumina(Al2O3) content in iron ore is also significantly high which demands for beneficiation as high alumina will create problem during iron making like higher fuel consumption, poor quality of slag produced, reduced productivity of B.F. all mineral has been engaged in hematite iron ore beneficiation with its gravity and magnetic separators since the mid-nineties. The delivery of jigs started for the upgrading of iron ore for its utilization in a Direct Reduction Plant in Australia. Since then, various other installations with jigs for lumps and fines as well as upstream separators for fines are in operation in Brazil, Australia, India and South Africa. Low grade run of mine and/or dump ores are being processed with alljig®-, allflux®- and gaustec®-WHIMS as the core equipment. The article describes the technology in use, the characteristics of various iron ores and the product qualities achieved. The data presented shows the specific advantages of jig application on iron ore upgrading due to the possible high gravity cuts and the easy and low cost operation. The allflux®- technology provides the big advantage of high capacities and a two-step process, both in a single unit. The gaustec®-wet high intensity magnetic separators offer high capacity in combination with unsurpassed process flexibility. Keywords: iron ore, gravity separation, jig, upstream classifier, wet high intensity magnetic separation (whims), pelletization, sinteringMineral processing is characterized by a constant adaptation to changing raw materials and market conditions. It is the link between the mined raw material and a marketable product. As a lot of high grade reserves are exploited, a steady deterioration of raw material quality can be observed. At the same time, the customers´ requirements for product purity and consistent quality increase. Indian iron ores are characteristically friable in nature that results in generation of sizeable quantity of fines (0-10mm) every year during various stages of mining and processing in the country with grade varying from 50-60% Fe(T) and are high in silica/alumina (Al2O3 5-8%). The fines generated cannot be directly used for iron making (blast furnace/DRI units) in the country due its physical and chemical properties; therefore, large portion of it gets exported or dumped. Value addition to iron ore fines through various activities such as beneficiation & palletization is the need of the hour, which will not only be economically beneficial to the mining sector in the long run but also generate value addition & employment opportunities. Incentives may be given for adopting latest technologies for direct use of fines in iron making by agglomeration of fines in the form of Pellets and Sinters, as fines forms considerable part of iron ore resources. Due to selective mining, although the iron content of the ore is high but the alumina(Al2O3) content in iron ore is also significantly high which demands for beneficiation as high alumina will create problem during iron making like higher fuel consumption, poor quality of slag produced, reduced productivity of B.F. all mineral has been engaged in hematite iron ore beneficiation with its gravity and magnetic separators since the mid-nineties. The delivery of jigs started for the upgrading of iron ore for its utilization in a Direct Reduction Plant in Australia. Since then, various other installations with jigs for lumps and fines as well as upstream separators for fines are in operation in Brazil, Australia, India and South Africa. Low grade run of mine and/or dump ores are being processed with alljig®-, allflux®- and gaustec®-WHIMS as the core equipment. The article describes the technology in use, the characteristics of various iron ores and the product qualities achieved. The data presented shows the specific advantages of jig application on iron ore upgrading due to the possible high gravity cuts and the easy and low cost operation. The allflux®- technology provides the big advantage of high capacities and a two-step process, both in a single unit. The gaustec®-wet high intensity magnetic separators offer high capacity in combination with unsurpassed process flexibility. Keywords: iron ore, gravity separation, jig, upstream classifier, wet high intensity magnetic separation (whims), pelletization, sintering

Sep 1, 2012

By M. Marinov

The Bulgarian deposits of quartz-kaolin raw materials are localized in the NE Bulgaria. For many years, the quartz-kaolin sand separation has been performing by water washing technology. After wet separation the raw material yields two products ? washed kaolin (different grades) and quartz sand (different grades). Research and development program has started to improve the quartz-kaolin sand separation. The program has undertaken an increasing of processing capacity, to decrease the losses in the tailings and to provide production of new quartz sand grades. The kaolin-silica raw materials from Vetovo open mine and the technological tailings from Vetovo processing plant were characterized. It was established that there are a lot of losses of quartz in final tailings. New approach on kaolin-silica raw material separation was tested in laboratory scale. The test work was performed on Derrick Stacksizer screening machines. The results of laboratory experiment show that there are possibilities to increase the quartz sand recovery and to start the production new grade sand. The full-scale pilot test was performed including the following units: two Derrick Stacksizer screening machines equipped with 0.430 mm and 0.150 mm opening Derrick Urethane Panel, respectively; Flat bottom DN 500 Hydrocyclone and DN 100 Hydrocyclon. The pilot test data clearly demonstrate that the Derrick Stacksizer screening machines are suitable for Bulgarian silica-kaolin raw material. Based on the test data a new quartz-kaolin separation technology was developed. The new technology was introduced in Vetovo processing plant increasing processing capacity and decreasing the losses of quartz in final tailings. Additionally the production of silica sand grade PK 0.16 is increased and starts the production a new grade PK 0.10.

Sep 1, 2012

By V. K. Gupta

Several approaches to the estimation of the size discrete breakage rate and distribution parameters (kj and bi,j ) of the batch grinding kinetic model are available in the literature. Analysis of a large amount of data available in the literature and our own data on several pure minerals and complex ores has shown that it is not always possible to obtain correct estimates of the two sets of parameters using known approaches as several widely different combinations of k and b parameters can sometimes simulate the batch grinding data reasonably accurately. It has been found that there are two main reasons: (i) all size classes are not well represented in the data and (ii) functional forms used for estimation of the two sets of parameters are sometimes chosen somewhat arbitrarily (especially in the case of complex ores), though they are actually uniquely related through size continuous breakage rate and distribution functions. A suitable experimental methodology has been described and demonstrated using some synthetic data and actual experimental data. A mill function approach, which does not require making any assumptions about the functional forms for k and b parameters, is also described and demonstrated. This approach is promising, but requires further development.

Sep 1, 2012

By John A. Herbst

The Mineral Processing Industry needs accurate Production Simulators for the design of future plants and expansions. To achieve this, these simulators should not only provide an accurate portrayal of the dynamics of individual pieces of equipment they should include the impact of discrete stochastic events such as scheduled and unscheduled maintenance so the relationships between availability, equipment sizes, and plant capacity are understood. To provide such a tool accurate dynamic Population Balance Models need to be combined with solid discrete event modeling. The current paper provides a description of how these two disparate modeling techniques were combined and the associated benefits from this combination. Keywords: dynamic plant simulation, population balance models, discrete event models, prefeasibility and feasibility studies, plant design and expansion

Sep 1, 2012

By K. Lillkung

The use of secondary sources has become a very attractive option in the production of platinum group metals as the demand for these metals has increased. One of the promising sources are the spent catalysts, which provide an attractive source as they have relatively high metal content compared with the ores where the metal is originally extracted from. The concentration of platinum group metals in catalytic converters is in the range of 0.1-1 mg/g as the concentration in ores is usually less than 10 ppm. Aqueous chloride solutions are claimed to be a cost effective way in which platinum group metals can be brought into solution and concentrated. In this work the effect of different parameters on the dissolution rates of Pt, Pd and Rh were investigated. The parameters investigated were the Cl- concentration, the temperature and applied potential. Chloride concentrations used were 62.5, 90, 125 and 250 g/l. Temperatures were 25, 40, 60, 80 and 94°C. Potentials were 950, 1050, 1150 and 1250 mV vs. SCE for Pt and Rh and 380, 410, 440 and 470 mV vs. SCE for Pd. Dissolution rates were calculated from the current densities determined by potentiostatic measurements. Thin wire electrodes were used in the measurements. As expected, higher temperature, higher potential and higher chloride content generally increasedthe dissolution rate. However, the effect was nonlinear and slightly different for different metals. The results show that strongly oxidizing conditions are needed in order to achieve reasonable dissolution rates. With the highest chloride content and at potential of 1250 mV vs. SCE and 94°C the dissolution rate of Pt was nearly 1 mm/h, whereas in similar conditions Rh achieved a rate of only nearly 100 µm/h. Similarly, with the highest chloride content and at potential of 470 mV vs. SCE at 94 °C the dissolution rate of Pd was nearly 1 mm/h. Keywords: Pt, Pd, Rh, redox potential

Sep 1, 2012

By E. T. Tuzcu

In this manuscript, a new approach for modeling the rate of grinding process is explained. A review about grinding rate definitions so far is given and the possible ultimate way for grinding modeling is given as modeling the rate based on energy spectra. The traditional/phenomenological approaches for modeling size distribution of grinding mills give their place to a new generation modeling technique. Developments in the computational methods and necessity to model product size distribution of large mills, larger than ball mill size, paved the way for this novel technique. The traditional grinding rate models are mostly based on the back calculated breakage parameters from the experimental data. However, direct modeling of breakage parameters and hence the prediction of size distribution of the grinding mills may become possible with this approach. The material breakage data and discrete element method (DEM) energy spectra are the main components of this approach. Albeit the focus in this study is on modeling of breakage rate under impact mode of breakage, the abrasion mode of breakage was also tested by carrying out abrasion tests. Impact mode of breakage was analyzed using ultra-fast load cell device (UFLC) and drop weight tester. Dry tumbling test was carried out for abrasion experiments. Obtained material breakage versus energy data are combined with the collision energy spectra to obtain the breakage rate function. In addition, the material breakage versus energy information from the tests is converted into breakage distribution function. The model was verified in a lab scale mill (90 cm diameter-15 cm length). 10 to 15 kg of limestone was ground using 50 mm steel ball at varying conditions, i.e., rpm, volume loading. It is shown that the proposed model predicts all (1, 2, 4 min.) grinding intervals for all experiments highly accurate.

Sep 1, 2012

By P. Matias

The study involved two projects that will produce copper concentrate and may have their operations integrated. Transport by trucks, conveyor belt, and the equipment called RopeCon were evaluated as options for the ore transport between the sites. A rainforest stretch, that Vale S.A. demands to preserve, is situated between the projects. It was suggested to further review RopeCon because it presents minimal interactions with the environment. To design the preliminary system layout, a research was done on the rainforest cover height data, but the information found was scarce and imprecise. For preserving the local forest, the use of this data would conduct to the oversizing of RopeCon towers and, consequently, overestimation of its costs. For the acquisition of reliable information, a method was developed using local data acquired through airborne laser survey. The volume between the digital surface and terrain models was calculated to generate a surface representing the forest cover height. It was revealed, by plotting the points obtained from this surface, that 85% of the vegetation is below 25 m. This height is suggested to review the preliminary project with a more accurate design of the equipment towers, thus reducing its costs estimates. The method permits the precise location of the large trees, making easier to find a pathway, for linear-shaped facilities, that would minimize the creation of vegetation-free zones as a measure to protect equipments against falling trees and forest fires. Keywords: forest cover, mining projects facilities, digital models, airborne laser survey

Sep 1, 2012

By Eberhard Gock

The worldwide implementation of corrosion protection of low alloyed automotive metal sheets by zinc coating has led to supply shortages of zinc free non-alloyed steel scrap in the foundry industry. In a collaboration project, partly financed by the German government, with partners from the automotive industry, zinc metallurgy, scrap trading, foundry industry, and plant construction, a new acid-based pre-dezincification process has been developed, and a pilot plant with throughput of about 100 t/d has been put into operation at the Clausthal Umwelt-Institut GmbH (CUTEC) together with the Clausthal University of Technology in Germany. During the treatment process, acid from a zinc metallurgical plant will be supplied, which can be recycled to the primary zinc extraction process after raising the zinc concentration to more than 130 g/L zinc. This way, the separation of small amounts of iron by precipitation and the electrolytic zinc winning are outsourced and, as a result, the pre-dezincification process runs waste-free. In Germany, the amount of zinc coated ?new scrap? is approx. 3 million t per year with a zinc content of approximately 60,000 t per year. The possible additional incomes for the dezincified steel scrap are in the order of ?40 to ?50 per ton of scrap, the gained zinc content during the acid dezincification defrays the costs of the process, if the throughput is more than 700 t/d. In comparison to conventional dezincification during the electro arc furnace process followed by upgrading in a rotary kiln (Waelz process), the acid dezincification process running at a maximum of 50°C will cut the energy costs by up to 74% and the CO2 emission by up to 88%. In fact, a demonstration plant is being designed right now and will be installed for processing a part of the zinc coated metal scrap from the Volkswagen AG in Wolfsburg, Germany. Keywords: steel scrap, zinc-coated steel, dezincification methods, acid

Sep 1, 2012

By Saeed Farrokhpay

It is known that the grinding condition has a major effect on the beneficiation characteristics of the minerals in subsequent processing, in particular, flotation. In the flotation process, particles surface and their condition can significantly influence collector adsorption and flotation performance. For example, particle shape and its surface roughness occurred during grinding may influence flotation characteristics of a specific ore. In fact, adsorption of different cationic and anionic species on mineral surfaces can be varied depending on the selected comminution procedure. The flotation performance of sulphide minerals can be detrimentally affected by the surface oxidation. The amount of surface oxidation may reduce the hydrophobicity of the mineral and makes adsorption of collectors less selective. Improved liberation may generally result in improved flotation recovery. However, this may result in finer grinding and slimes, and consequently, reduce the overall flotation recovery. This paper discusses the effect of wet and dry grinding on copper flotation of a complex Cu-Pb-Zn ore. Industrially, wet grinding is preferred due to its higher energy efficiency and owing to downstream processing requirements. In this study, series of flotation tests were conducted,and surface analysis (XPS and ToFSIMS) were performed after wet or dry grinding at two different P80 values. Mineralogical study was also conducted to investigate the liberation of valuable minerals after grinding. A higher copper flotation recovery was found for wet grinding. However, the copper recovery was increased by further grinding in both conditions (wet and dry). The results showed a higher collector adsorption on copper mineral surfaces after wet grinding. The surface analysis also revealed that the ore is slightly more oxidized after dry grinding probably due to higher temperature during dry grinding.

Sep 1, 2012