Search Documents

By C. Igathinathane

Coal is the most widely used fossil fuel in the world, providing more than 25% of world?s electrical power. Since, the behavior of coal particles in crushing and grinding circuits, concentration operations, and solid-liquid separations is strongly dependent on size, a reliable and accurate measurement of particle size and particle size distribution (PSD) is a vital aspect in coal cleaning. This paper presents a method for the characterization of ground coal particles using image analysis. We utilized a machine vision (MV) approach that used a document scanner as the imaging device and a user-coded ImageJ plug-in that processed the image and automated the PSD analysis and output results in textual and graphical forms. This approach used a sum of volumes (SVolume) as weighting factor for particle length as the primary dimension of analysis and was successfully applied to ground coal. The plug-in was further improved for computational performance in this study. Mechanical sieving (MS) was also used to compare the MV results. MV results showed that the PSD of ground coal followed a uni-modal normal distribution, and the log-normal plot against particle size exhibited a linear trend for most of the range. MS results, however, had three linear segments, when the width-based sieving results were transformed to lengths by applying the shape factor (width/length), but a definite deviation between the PSD plots was observed. This study demonstrates successful application of the MV SVolume approach for PSD analysis of ground coal, which can be extended to similar particulate minerals and products. Keywords: dimension, fiji, image j, image analysis, coal, particle size, plug-in

Sep 1, 2012

By Alok Tripathy

A simulation code called SIMJIG and the user interfaces have been developed using discrete element method (DEM) and the .NET platform respectively for the jigging process. DEM platform is used for tracking of particles in the jigging operation. DEM uses the net force balance on the particles to track the trajectory of the particle. Simulation results are compared with experimental results obtained by jigging of low grade iron ore lumps. Two different iron ore samples one from Chatishgarh and one from Odisha were used for the experimental studies. The Alljig? stratification test rig meant for batch laboratory experimental studies has been used in the present work. The behavior of different sizes of material on jigging has been examined. Later, the particle size behavior during jigging at different layers of the jig bed has been studied. Further stratification profile across the jig bed has also been studied. It was observed that simulation results are matching quite nicely with the experimental results. The SIMJIG simulator developed in the present study could be used for predicting the performance of the jigging operation effectively. Keywords: DEM, gravity concentration, jigging, iron ore, simulation

Sep 1, 2012

By P. M. Solozhenkin

On the territory Sakha (Yakutia) are located largest in Russian Federation reserves of antimony ores, Sarylakhsk and Sentochansk deposits, amaunt 10% of world stocks of antimony. A processing gold antimony ores Sarylakhsk deposit is carried out on gravitation-flotation circuit to receive gold gravitation concentrate and gold-antimony flotation concentrate with the contents of antimony over 60%. The gold-bearing concentrate is treated on place hydrometallurgicaly to a high-standard product, accepted by gold bank cash department. At the ore dressing plant reached the highest recovery in world in a concentrate of antimony 90%~91.6%, and gold 85.7%~86.0% as a result of scientific research works. Studied the mechanism of interaction cations of metals Pb2+, Cu2+, Cd2+, Hg2+, Ag+ with a surface antimonite presented on the basis of modern physical-chemical methods: nuclear quadrupol resonance, x-ray electron spectroscopy, electron spin resonance. The industrial tests of sodium dimethyldithiocarbate were carried out which confirmed high recovery of Sb and As. The leaching Sb2S3 by bacteria Desulfovibro desulfuricans and transformation antimonite in antimony trioxide by Tiobacillus Ferrooxidans improved following cyanidation . The extraction of antimony in a solution 96.0%~98.0% under optimal conditions. The common total extraction in the appropriate commodity products for gold reached 98%, for Sb 96.5%. At a combination of bioprocessing and cyanidation 85.5% of extraction Au was achieved. The new solvents for antimonite were found. Now by the Close Joint-Stock Co ?Sarylach-Antimony? industrial plant is constructed for processing Au-Sb concentrates to receive antimony trioxide and gold from various antimony deposits of Sakha (Yakutia).

Jan 1, 2014

By M. Saghaeian, R. Hejazi, A. Dehghani Ahmadabadi, M. Zare

"In the most iron ore beneficiation plants, reverse flotation is the best method for removing silicate gangues from final iron ore concentrate. Many previous studies show, if the major portion of impurities include quartz minerals, the flotation process is simple, but if iron silicates are dominant, reverse flotation is so complicated and mostly not very effective. In this study which was performed on the Sangan iron ore concentrate, the performance using of reverse flotation and magnetic flotation separator for elimination of silicate gangues from the magnetic iron concentrate was investigated. The operational parameters for reverse flotation are considered as: collector and frother types and dosages and also modifiers. But for magnetic flotation separator parameters were magnetic field intensity as well as overflow and underflow water rates. Results showed that reverse flotation has not a significant effect on the elimination of impurities. Because of the silicate gangues of Sangan concentrate including a mixture of quartz and iron silicates (amphibole, pyroxene and feldspar), so downgrading of the SiO2 content for the flotation concentrate was rather low and only average reduces of 20.60% were possible. But the findings of using magnetic separator was more satisfactory. Results of the weight recovery, iron grade and also SiO2 and S grades of final concentrate were better with magnetic flotation device. So at the best and optimum condition, we could reduce 51.01% of the total silicate (SiO2~ 2.19%) along with 74.66% of sulfur content (S~ 0.076%) and concentrate weight and Fe recoveries of 92.04% and 94.51% respectively, final Fe grade of 68.73%.INTRODUCTION Chemical/traditional flotation is one of the most effective methods for separating valuable particles from waste minerals, which is used in most mineral processing industries. In the iron ore processing industry, the major impurities present in iron ore concentrate include sulfur, silica and phosphorus (Bruckard et al, 2015), which are often carried out by reverse flotation methods for the removal of sulfide and oxide impurities (Donald, 1967: Araujo et al., 2005: Ma, 2012)"

Jan 1, 2018

By S. F. Ye, L. Xiao, Y. L. Wang, P. W. Han

"Copper anode slime is a precious secondary source for the recovery of silver. However, current recovery process are constrained by either sever pollution or high cost. To cover the drawbacks of current process, this research employed a novel strategy by using the manganese dioxide as the oxidant in acid solution, which avoided the generation of sulfur dioxide while high silver extraction rate was achieved. The effects of manganese dioxide, sulfur acid concentration, stirring speed, temperature and leaching time on silver extraction rate were investigated. The silver recovery reached to 91.68% under the conditions of 1.2 g manganese, 2.0 mol/L H2SO4, 300 rpm, 80 °C and 6 h. INTRODUCTION Copper anode slime is generated from the electrolysis refining of copper and is extremely precious for its containing noble metal such as silver (Chatterjee, 1996; Amer, 2003; Yldrm et al., 2014; Syed, 2016; Wang et al., 2017). Therefore it is of great significance to extract silver from anode slime for the full utilization of resource. Pyrometallurgy is the most mature process for the extraction of silver because of its stability and adaptability (Hait et al., 2009; Zhao et al., 2010; Gao et al., 2017). However, it also suffers the drawbacks of high operating cost, low extraction rate of silver and severe pollution of smoke dust (usually containing lead and arsenic) (Ludvigsson and Larsson, 2003). To cover the drawbacks of pyrometallurgy process, more and more attentions are giving to the semi-hydrometallurgy process which usually includes a pretreatment process of sulphatising roast or low temperature oxidizing roasting (Tishchenko, 1964). After pretreatment, the refractory silver bearing phases (silver selenide, silver sulfide and silver) are converted into readily leached forms which are often extracted by ammonia, sodium sulfite in alkaline solution (Valiuniene et al., 2010; Wojciech, and Kitka, 2017). Despite its relatively high extraction rate and low investment, it still has the disadvantages of releasing harmful gases since the sulfur dioxide are generally generated in the pretreatment process. In addition, the use of ammonia can easily lead to a leaking into the atmosphere once not carefully dealt with (Aylmore and Muir, 2001). As for silver recovery by sulfite leaching, the consumption of sodium sulfite is rather high which often results in a pipe blocked (Yang et al., 2006)."

Jan 1, 2018

By A. Ghadyani

This investigation was undertaken to assess the possibility of ash and sulfur removal by microbial action of high sulfur-content coal. Thiobacillus ferrooxidans and Thiobacillus thiooxidans have been used for biodesulfurization of coal. Feed samples were provided from Tabas coal mine located in Yazd province, Iran. The sample contained 28.80% ash and 2.30% sulfur. Flotation tests were implemented to optimize the effective parameters in these cells which were constant during bio-flotation tests. According to the results, obtained from various tests using Taguchi orthogonal array design (L27), the values of optimized parameters were pH at 7, 1000 g/t gas oil as a collector, 10% solid content, 15 min conditioning time, 100 g/t MIBC as a frother and 800 rev/min rotor speed. Bio-flotation tests are carried out by means of laboratory double discharge cell and mesophilic bacteria as depressant reagent using above mentioned optimized parameters. The bio-flotation experiments were conducted based on a Taguchi orthogonal array design (L9) with four variables (bacteria type, bacteria count, rotor speed of mixer and bio-conditioning time). The collected data was analyzed by using DX7.0, Minitab14.0 and WinRobust1.02 softwares for evaluation the effect of each parameter on the optimization criteria. Considering the highest combustible recovery and the lowest ash and sulfur content, the value of optimized bacteria type, bacteria count, rotor speed of mixer and bio-conditioning time were Thiobacillus ferrooxidans, 5×107 cells/g(coal), 100 rev/min and 20 min respectively. Under this condition, ash and sulfur content and combustible recovery were predicted 12.39%, 2.08% and 82.03% respectively.

Sep 1, 2012

By Y. L. Tian

Low-grade bauxite with A/S of 4.4 from Henan province was used as raw material and the selec-tive grinding of bauxite, grinding efficiency, particle size and Al2O3 and SiO2distributions of ground products were investigated using ball and vibration mills. The results show that the selective grinding can be used to realize the separation of aluminum from silicon within a certain particle size. The optimal grinding conditions of the ball mill with bauxite are as follows: grinding material to charge ratio, 1.2, charge volume ratio, 40%, pulp con-centration, 70wt%, medium size distribution, F30mm:F20mm:F15mm=20%:50%:30%. Under the conditions, the weight rate of ground product with A/S over 7.5 is 27% and the recovery of Al 2O3is 30%. The optimal grinding condition of the vibration mill with bauxite are as follows: grinding material to charge ratio, 0.9; charge volume ratio, 70%; concentration, 70%; medium size distribution, F40mm:F30mm:F20mm=20%:30%:50%. Under the conditions, the weight ratio of ground product with A/S over 7.5 is 25% and the recovery of Al 2O3is 27%. The research is significant for the rational and economical utilization of the low-grade bauxite.

Jan 1, 2014

By Benoit Clermont, Jan Lux

"Magotteaux and Anglo Platinum started a co-operation program with the main aim of establishing the optimum milling configuration measured in terms of throughput, fineness and energy consumption.For this purpose, a fully instrumented pilot milling plant, supplied by Magotteaux (Pty) Ltd, and equipped with a 0.9 x 1.0 m ball mill, was erected at Frank concentrator (Merensky Pt ore). The primary ball mills at Frank concentrator were surveyed in order to set the conditions for the base case. This data was then replicated in the pilot mill under the same configuration. Thereafter, a series of different parameters were varied in order to attempt to optimize the milling system.Some of the grinding parameters that have been studied are:•,Gate versus overflow discharge•,Open versus closed circuit•,Different filling degrees•,Different shell liner profilesOnly grate versus overflow discharge and open versus closed circuit will be discussed in this paper.It should be noted that this paper does not attempt to give a universal solution as to what milling configuration is optimum in all cases. The conclusions apply for this particular case and probably most others, but it would be advisable to consider each case on its own."

Jan 1, 2003

By G. Atesok

Turkey?s EU affairs started in 1963 with the Ankara Treaty. On 31 December 1995 the Customs Union between Turkey and the European Union came into effect. In order to achieve the Copenhagen Criteria?s, Turkey, made laws parallel to the Framework Programs. On 3 October 2005, with the confirmation of ?Membership Framework Document? the negotiation process of Turkey has started. Coal had important role in the industrialization of EU and it is directly related to Energy and Environmental subjects. In this point many restriction became with the some protocols, in last decades. European Union composed Energy and Coal Policy, therefore engaged to reduce the emissions, and made new regulations. This regulations concern Turkey?s energy future, since large; but low quality of lignite reserves of Turkey, it is expected to have some difficulties with Union?s Environmental Legislation during Turkey?s congruity process. With the last natural gas import agreements of Turkey, the production and consumption of coal sunk in last seven years. However, considering environmental sustainability, the role of coal in energy production will rise up in the coming future. In this paper, in terms of Turkey Energy Sector, production and consumption problems of coal discussed and evaluated considering EU?s coal, energy and environmental rudiments.

Jan 1, 2014

In flotation, particulate materials are separated by controlling the hydrophobicity of the particles using appropriate collectors. In this regard, contact angle (?) is the most important process variable. However, the flotation models used in industry today do not include ? as a parameter. As result, flotation circuits are designed based on the first-order flotation rate constants (k) determined from laboratory experiments. A problem with this approach is that laboratory experiments usually give substantially higher k values than achievable in full-scale operations, which makes it difficult to use the model for plant design. In the present work, we have developed a model from first principles using both surface chemistry and hydrodynamic parameters, such as ?, ?-potentials, surface tension (?), particle size, energy dissipation rate, etc. The basic approach is similar to the one developed previously for bubble-particle interactions under laminar flow conditions (Yoon and Mao, J. Colloid and Interface Science, 181, 61, 1996) except that the model parameters have been modified by considering the turbulence in a flotation cell. In addition, the model describes the recovery processes in froth phase, including bubble-coarsening due to coalescence. Based on this model, we have developed a computer simulator (FlotSim) that can be used to design flotation circuits from the mineralogical (or liberation) data on the feed and the hydrodynamic characteristics of a flotation machine. Since the model is dynamic, it can also be used for process control. Further, the simulator has predictive capacity as it is based on a first-principles model. The model-based simulator has been validated in a carefully controlled bench-scale flotation experiments. Keywords: flotation kinetics, flotation model, contact angle,?-potential, size-by-size recovery, liberation, DLVO theory

Sep 1, 2012

By John Jiang, Brian R. Hart, Stamen S. Dimov, Aparup Chattopadhyay, Barun K. Gorain

"This paper presents a systematic approach to metallurgy diagnostics using an integrated gold deportment methodology developed for complex refractory gold and copper-gold ore bodies. Quantification of gold deportment for these ore bodies is a challenging task due to reasons such as lower grades, high variability of visible and invisible gold content in different sulphides and iron oxide phases, significant presence of disseminated and composite carbonaceous matters along with associations of various copper sulphide phases. Some case studies are presented in this paper to demonstrate the value of a high confidence gold deportment methodology in developing insights for problem diagnostics and to identify opportunities for metallurgical improvements. A holistic approach involving different fields of expertise is critical for successful development and delivery of solutions for complex ore bodies.INTRODUCTION Studies were initiated on various ore complex ore and also on samples representing various process streams. These complex copper-gold single refractory, double and triple refractory gold ores are mainly composed of silicates and/or carbonates with moderate amounts of clay and mica, along with minor amounts of sulphides and organic carbonaceous matter. Variable proportions of visible gold and “invisible gold” (sub-microscopic gold) were noted in different mineral phases for various ore types and process stream samples. Invisible gold commonly occurs as solid solution or as colloidal-sized particles in different sulphides (pyrite, arsenopyrite, pyrrhotite, chalcopyrite and galena) and other phases (including hematite, magnetite and goethite) for different refractory ores. The dominance of invisible gold and presence of highly preg-robbing along with finely disseminated carbonaceous matters adversely affects gold recovery in flotation and leach circuits for most of these double and triple refractory ores. This paper discusses applications of an integrated gold deportment technique developed for different types of gold and copper-gold ores, namely, complex copper-gold, double and triple refractory gold ores (Chattopadhyay and Gorain, 2014; Chattopadhyay et. al., 2016). Various process streams from flotation and gold leaching circuits were investigated. Different concentrates and tailings samples from flotation circuits whereas feed and discharges from pressure oxidation (POX) and carbon-in-leach (CIL) residues were used from gold processing circuits."

Jan 1, 2018

By G. Demi

Chromium ore exploitation has commenced in 1948 in Albania and there are produced about 24.3 million tons up to the end of 2006. Last years the prices and need were increased notably. Main export of chromium ores and concentrates was accomplished respectively 114 500 ton and 13 000 ton in People Republic of China during 2006 year. Location, status, reserves and grade of chromium deposits of Albania are presented in the paper. Chromium ore enrichment is related with their composition and Cr2O3 content, as well as with market requests. Actually, high grade chromium ores with Cr2O3 content over 38% ~ 40% are directly exported or treated in metallurgy, but last time have been exported and chromium ores with 28% ~ 30% Cr2O3 content for the reason that dressing plants can not be operated for investment lack. High grade chromium ores have been treated in heavy media separation plant before 1990. It is presented flow sheet, figures and necessity to put in operation HMS plant in the paper. Actually, low grade chromium ores with content 16% ~ 20% Cr2O3 are not enriched for the lack of investments, but before 1990 they have been concentrated in dressing plants producing chromium concentrates grade 48% ~ 50% Cr2O3. In the paper are shown technological schemes and industrial figures during more than 20 years operation and possibilities to reconstruct these mineral processing plants. Only chromium mineral processing plant of Bulqiza is in operation using as raw material its old existing tailings. The flow sheet and figures show that are possibilities to increase recovery and grade of concentrate in the plant. Separation and concentration of slimes in suitable equipment gives visible improvement of Cr2O3 recovery. Several tests have been carried out with flotation and magnetic separation methods for enrichment of low grade chromium ores. Flow sheet and figures of mineral processing ores content olivine as gangue mineral are interesting, because combination of gravimetric with magnetic methods is necessary in this case. In the paper are presented the tests and good results of low chromium ore pre concentration. Metallurgical treatment of chromium ores to produce Ferro chrome, as well as technological process, figures, consume of electrical power and materials in Elbasani and Burreli furnaces are shown and necessary investments to treat in metallurgy all produced chromium ores in Albania are considered.

Jan 1, 2014

By Aline Tavares

This paper describes the investigative studies carried out at Vale´s Center of Mineral Development (CDM) for a nickel sulfide deposit aiming to develop an adequate flotation flowsheet. The CDM facilities comprises of very well equipped laboratories to develop hydrometallurgical, comminution, flotation, physical separation processes, besides chemical and mineralogical laboratories, that are required to accomplish pre-feasibility studies, new process routes developments and, eventually, brownfield projects. Close association of the flotation group with the geometallurgy and the mineralogy teams play a key role during greenfield project development. Most of the information required by process engineers responsible for the flowsheet development can be provided by the mineralogy team and its mineralogical laboratory at CDM. During the flowsheet development of this nickel sulfide deposit, two ore types were identified as the most abundant in the deposit, named biotite-chlorite hydrothermalite (HID) and magnetite hydrothermalite (MAG HID). Six samples were selected for the investigative studies based on this initial information. Nickel grade varied from 0.39% to 1.95%. The main nickel-bearing minerals were millerite and pentlandite whereas the main non-sulphide gangue minerals were quartz, plagioclase, biotite, chlorite, actinolite, and/or magnetite. Electron microprobe (EMP) identified the presence of nickel in solid solution in gangue minerals such as biotite, chlorite, and actinolite. Nickel deportment in silicates varied from 3% to almost 40%. Magnesium was distributed in biotite and chlorite, except in sample MAG HID, in which talc was responsible for almost 50% of the Mg content. Liberation studies indicated that the optimum feed grind size was around 150µm and that pyrite occurred highly associated to the nickel sulfides. The flotation tests were planned based on the information provided by the mineralogical data. Rougher flotation tests indicated that the optimum P80 of the primary grind was 212µm for the HID type and 150µm for the MAG HID. From the reagents tested, amyl xanthate proved to be the most efficient in the recovery of the sulfides. In the MAG HID sample talc was well depressed by dosing 600g/t of CMC. Nickel recoveries in the rougher stage were lower than 90% due to the nickel distributed in silicates. However, sulfur recovery was around 95%, indicating high recovery of the total sulfides. Open circuit and locked cycle tests were conducted to evaluate the effect of the regrind size in the nickel grade and recovery (P80 of 44µm and 20µm). Nickel recovery decreased from 70% to 65% when finer regrind size was tested. Although nickel recovery decreased by 5%, the finer regrind size lead to a higher Ni grade (from 11% to 23%Ni) and lower fluorine grade (from 1138ppm to 700ppm) in the concentrate. Keywords: nickel sulfide, flotation, mineralogical characterization, flowsheet development

Sep 1, 2012

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 Longjiang Li, Mao Jiang, Zhihui Shen, Guizhou University, Yin Pan

This paper aims to study the influence and action mechanism of collector Y-89 on the flotation of auriferous pyrite. The measurement to identify adsorption quantity, IR and XPS spectrum analysis and flotation experiment made on the pure mineral were conducted. The research results show that when the dosage of MIBC is 20 mg/L, and pH of 8, the dosage of Y-89 over 60 mg/L, the pyrite recovery rate is greater than 80%.And when the dosage of Y-89is 60 mg/L, dosage of MIBC 20 mg/L, the pH in a wider range (pH=4~9), the recovery is greater than 75%. When the pH is above 10, the pyrite is depressed and its recovery rate is found to be dramatically dropping. Adsorption quantity measurement also shows that the strong alkaline conditions inhibit the adsorption of Y-89 on the surface of auriferous pyrite. IR measurement indicates that chemisorption of Y-89 occurs on the surface of auriferous pyrite. XPS spectrum analysis indicates that without adding Y-89, oxidation reaction occurs on the surface of pyrite. But when Y-89 is added, the chemical environment of Fe on the surface of pyrite has changed. Such findings indicate that with Y-89, chemisorption occurs on the surface of auriferous pyrite.

Jan 1, 2014

In recent years, coal beneficiation has gotten considerable attention. Selective oil agglomeration has been accepted as the best method to produce clean coal with a high removal of pyrite sulphur. In this study, spherical oil agglomeration of Datong coal fines was carried out using diesel oil as a bridging liquid. The oil agglomeration has a surface properties based on coal cleaning technique. The effects of fundamental parameters have been investigated including the concentration of bridging liquid, the size of coal particle, the solid content of slurry, the agitation time and rate, pH, surfactants on the agglomeration performance and various salts on the ash rejection and removal of pyrite of the agglomerated products. The optimum conditions of particle size, diesel concentration, solid content, agitation speed and time, pH and the dosage of active agent have been determined as less than 8µm, 20wt%, 1200r/min and 10 minutes, 7.5g/t and 100g/t, respectively. Under these conditions the ash content in the products can be achieved 1.5% below, the ash rejection was up to 92%. It has been observed that ionic strength of the aqueous medium affects the agglomeration performance. The precombustion coal cleaning process based on improved selective agglomeration results in high ash and pyrite sulphur removals. Over 80% removal of pyrite sulphur can be achieved from run-of-mine coals by offering a more cost-effective sulphur reduction solution rather than any other SO2 removal technology. In addition, the removal of pyrite sulphur is very necessary for not only the prevention of environmental pollution but also economical reasons.

Jan 1, 2014

By R. Sakthivel

Blue dust is a high grade soft haematite material containing 96.14% Fe2O3 transformed into magnetite (Fe3O4), when it is subjected to planetary ball milling in the presence of iron powder as reducing reagent. X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM) and Laser particle size analyser have been employed to characterize various samples collected at various milling times to know the phase evolution, particle size distribution and morphology of particles. X-ray diffraction studies reveal the formation of magnetite phase at the optimum milling time of 40 hours. Vibrating sample magnetometry (VSM) study demonstrates, that sample obtained at 40 hours of milling time exhibits saturation magnetisation of 14.757 emu/g whereas the starting material used in this study shows only 1.0425 emu/g. Keywords: Blue dust, reaction milling, magnetite, saturation magnetization

Sep 1, 2012

By Zhu Yangge, Hu Xiaoxing, Feng Qiming, Zhang Guofan, Zhang Xingrong

"During the flotation process of ilmenite and titanaugite with fatty acid as collector, unavoidable ions such as Ca2+, Mg2+, Al3+, Fe3+ and Fe2+ demonstrate considerable influence on the floatability of the minerals. In this study, flotation test, zeta potential test, and solution chemistry calculation were adopted to investigate the mechanism of how these metal ions affect the floatability of ilmenite and titanaugite in different pH conditions. The results show that in weak acidic solution, Ca2+ and Mg2+ mainly freely exist in the solution with little adsorption on mineral surface, and their reaction ability with oleate ions is weaker than active site on ilmenite surface (Fe), thus they show negligible effect on the flotation of ilmenite; Al3+ shows similar reaction ability with oleate ion compared to Fe3+, which lead to competitive reaction with collector, so the flotation of ilmenite is depressed. While Fe3+ can adsorb on surface of titanaugite in the form of Fe(OH)3, and it shows stronger reaction ability with oleate ion compared with active site on titanaugite surface (Ca and Mg), which proves an activation effect on titanaugite flotation. In alkaline solution, all these five kinds of ions can adsorb on titanaugite surface, and the floatability of titanaugite will be activation. Based on the above analysis, it can be deduced that in the flotation system using fatty acid as collector, the adsorption of metal ions on mineral surfaces and the stronger reaction ability with collector than active site on mineral surfaces, are the two prerequisites for metal ions show activation effect on mineral flotation.INTRODUCTIONIn flotation pulp, the existence of metal ions is often inevitable. There are two sources for these metal ions: the first part is generated in grinding and flotation process due to the oxidation, reduction, corrosion or dissolution of minerals or grinding medium; the second part is from the flotation water or the addition because of the technology need. The metal ions in the pulp have a considerable influence on mineral flotation. Earlier researches are focus on the activation effect of mineral floatation by metal ions to obtain a higher flotation efficiency, many effective activators were found, such as Cu2+ activated sphalerite, Pb2+ activation wolframite, and Ca2+ activation quartz flotation, these metal ions have become the commonly used activators in industrial production. And many studies attempted to explain the mechanism of how metal ions affect the floatability of minerals. James (James et al, 1972) suggests that metal hydroxide precipitation is the main component leads to activation effect, while the study of Fuerstenau (Fuerstenau, 1976) showed that the metal ion hydroxyl complexes played significant role. In recent years, the reuse of mineral processing wastewater has attracted more attention (Rao et al, 1989; Liu et al, 2013; Wang et al, 2014), as a main component in flotation wastewater, the influence of “unavoidable ions” on flotation process still need in-depth study."

Jan 1, 2018

By O. Celep, H. Deveci, Ersin Y. Yazici, F. Ahlatci

"There are increasingly stricter environmental regulations imposed for use of cyanide leaching for the extraction of gold from ores. Alternative lixiviants to cyanide, preferably with low toxicity, have been extensively studied. Thiosulphate has emerged as one of the most suitable alternative leaching agent in place of cyanide due to its low toxicity and technical attributes e.g. fast leaching kinetics, high gold extractions from carbonaceous ores in particular. High solubility of most copper minerals in cyanide solutions results in low gold extractions due to excessively high consumption of cyanide. In contrast, low reactivity of copper minerals in thiosulphate solutions makes thiosulphate leaching potentially suitable alternative for treatment Cu-bearing gold ores. The extraction of gold/silver from a copper-bearing pyritic gold concentrate (62 g/t Au, 110 g/t Ag and 0.3% Cu) in thiosulphate solutions was investigated in this study. The concentrate is composed of predominantly quartz (25%) and pyrite (32.7%) as well as sphalerite (5.37%), galena (2.12%) and anglesite (1.13%). Other minor minerals are arsenopyrite, chalcopyrite, covellite and bournonite. Previous studies by the authors indicated that the concentrate did not respond well to cyanide leaching (i.e. 45-46% Au/Ag at 1 g/L NaCN). The effects of concentration of ammonia (0.2-1.5 M NH3), thiosulphate (0.1-0.75 M S2O3) and copper (0-20 mM CuSO4) on the extraction of gold and silver over 8 h. was investigated. Increasing the concentration of thiosulphate and ammonia substantially improved the rate and extent of gold leaching while high copper levels produced an adverse effect particularly at low concentration of thiosulphate (i.e. 0.1 M). Complete extraction of gold was achieved under suitable conditions. In contrast to gold, silver extractions remained consistently at low levels (i.e. 28%). These findings demonstrated that thiosulphate leaching could be used to achieve acceptable levels of gold extraction from the copper-bearing pyritic gold concentrate."

Jan 1, 2018

By J. Botula

In the region of the North-Bohemian Coal Basin and its environment, there, in a row of places, are found the accumulations of rocks of the sedimentary and pyro clastic origin, the preliminary composition of those shows the possibility of their being utilized for the production of ecologically sparing natural Fe- and Ti- pigments and filling substances. In many places of the regions of Chomutov and Podborany and near Bilina and also in other places, there are found raw stocks perspective for the preparation of yellow up to ochre-brown, red, brown-red and green dyes. The target of project is the verification of dispensable reserves, their mineralogical composition and chemical and physical attributes, verification of treatment ways of Fe-and Ti-pigments separation (hydrocyclones, magnetic and electrostatic separation) and their stabilization and technological painting attributes for applications in colors, coating and plastic masses, mortar mixtures etc.

Jan 1, 2014