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Rotor speed is one of the key hydrodynamic parameters in froth-flotation and it plays an important role in bubble-particle attachment. Laboratory scale studies for optimizing the rotor speed to achieve maximum flotation rate constant (K) of quartz, ground by ball mill, are. Purity of quartz was 99.4 percent and d80 of ball mill product was 230 µm. Each size fraction was separately subjected to flotation at three different rotor speeds, namely, 1200, 1000 and 800 rpm, and the flotation rate constant was calculated. The results showed that the flotation rate constant was high at the rotor speed of 1200 rpm. The flotation rate constants achieved at 1200 rpm were 8.676, 8.232, 7.818, 7.248, 7.068 and 6.984 min-1forthesize fractions of +300, -300+250, -250+212, -180+150, -150+125 and -125+106 µm, respectively. Keywords: froth flotation, rotor speed, flotation rate constant, ball mill, quartz

Sep 1, 2012

By Kazutoshi Haga, Batnasan Altansukh, Atsushi Shibayama

Results of flotation process combined with atmospheric leaching and high pressure leaching for recovery of copper from low-grade silicate-copper ore have been presented in this study. The low-grade copper ore contains a small amount of copper (0.42 mass %), iron (4.6 mass %), and silicon (38.3 mass%) and among many other metals (Al, Ca, K, Mg, Na, Ti and S). The main mineralogical constituents of the copper ore are calcium aluminosilicate (Ca(Al2Si2O8), amesite (Mg2Al2SiO5(OH)4) and gypsum (CaSO4×H2O), and quartz (SiO2) as resulted from the alteration of an igneous rock. This study has shown that about 92 % of copper can be recovered with a maximum copper grade of 4.2 mass% in a froth after 15 minutes of flotation at pH 8.5 when used potassium amyl xanthate as a collector, MIBC and Dow-froth 250 as frothers and calcium hydroxide as a pH adjuster. The images of bubbles in the cell during flotation process were recorded using a high-speed camera. The froth concentrate with average copper grade of 2.0 mass% was further processed by atmospheric leaching with a solution of sulphuric acid and hydrochloric acid, respectively and high pressure leaching with sulphuric acid solution. As a result, leaching rate of copper reached about 60 % in an atmospheric leaching with sulphuric and hydrochloric acid respectively, whereas the rate can reach more than 70 % by autoclave leaching at high pressure under the controlled condition. A process to recover of copper from its low-grade ore can be developed by optimization of flotation combined with acid leaching.

Jan 1, 2014

By Kazutoshi Haga, Atsushi Shibayama, Kosuke Nishioka, Yasushi Kihara, Altansukh Batnasan

The aim of this study was to investigate the feasibility studies of seawater in flotation of a 1.5 mass % of copper containing copper sulfide ore. Effects of seawater, various frothers, and different distilled water/seawater ratio on flotation of copper sulfide ore were studied. Surface properties of native copper ore and sea water soaked were examined by using FT-IR spectrometry. Chemical contents of the copper sulfide ore and after flotation were identified using XRD studies. XRD pattern showed that the main constituents of the copper sulfide ore are chalcopyrite (CuFeS2), bornite (Cu5FeS4). Flotation experiments were carried out using mechanical agitation flotation equipment with a mineral separation type flotation cell. Froth flotation experiment was conducted using calcium hydroxide was used as a pH adjuster, using methyl isobutyl carbinol (MIBC), dow froth 250 (DF 250) as frothers and potassium amyl xanthate (PAX) as collector for the copper recovery from the copper sulfide ore containing chalcopyrite and bornite. The results showed that the copper recovery by flotation was dependent on the flotation medium and frother. The main results showed that the copper recovery by flotation was dependent on the process water and frother. The copper recovery reached 97 % and 87 % in the distilled water flotation and seawater flotation with MIBC, respectively. For seawater flotation with DF 250, the Cu recovery achieved near 95 % and grade of Cu in the froth product after 5 min flotation was reached 29.8 mass %.

Jan 1, 2014

By Peter N. Holtham, Mary M. Ng

"Resistivity measurements of minerals in the laboratory are commonly made with a low DC voltage source. Common test voltages specified in the ASTM Standard D257 are 100, 250, 500, 1000, 2500, 5000, 10000 and 15000 V, however 100 and 500 V are the most frequently used. Resistivity results obtained in the laboratory have been used to infer the electrical behaviour of minerals undergoing electrostatic separation. However because the voltages employed in electrostatic separation in the plant are of the order of thousands of volts, typically greater than 15000 V, whether the laboratory results are applicable as a predictor of plant performance is a critical question. It is unclear whether resistivity values taken at a low voltage are characteristic of those seen in electrostatic separation, in which the minerals are exposed to a much higher voltage. No definitive answer could be found in the literature.In this work, the resistivities of zircon, rutile and ilmenite were measured in a corona field for the first time. The measurement principle was based on a technique developed to measure fly ash resistivity in electrostatic precipitators, however the test apparatus and findings are novel.Resistivities of rutile and zircon were found to be easy to measure. The values measured in a corona field were several orders of magnitude less than those obtained with a dc voltage of 100 V. Evidence of back corona was observed with zircon. When the voltage drop was greater than the sample layer could withstand a localised electrical stress developed, resulting in a voltage breakdown, at which point a sudden surge of corona current (back corona) was detected in the sample layer. Rutile, on the other hand, exposed to the same conditions as that of zircon (i.e. same temperature and applied voltage) did not exhibit any sign of back corona. Its resistivity across the range of test voltages (14 to 33 kV) remained fairly constant."

Jan 1, 2003

By V. Sheikhzadeh, M. Saghaeian, R. Hejazi, A. Abazarpoor

The research aimed to compare the chemical analysis (K, Na, Cl) of Iranian concentrate plants, which are the main source of materials corrosion in the pelletizing plants. Cl alongside alkaline elements (especially K) may cause corrosion and plug in the grate plates and other involved equipment. Therefore, it is tried in the processing plants to remove impurities from the concentrate to prevent potential problems in pelletizing and iron/steel making processes. Part of these impurities are existed in the nature of ores and others are sourced in the processing water. Various samples from the largest Iranian concentrate plants including Chadormalu, Gol-e-Gohar, Jalal-Abad and Sechahun were prepared to investigate the possibility of alkaline problems for each samples. The amount of Cl, K and Na of Chadormalu sample was obviously low and therefore no alkaline problem is expected. The Cl content of Gol-e-Gohar sample was high (980 ppm) while amount of K was less (0.008 Wt. %). Due to low content of K, most of Cl will release as Cl2 or HCl and so problems caused by KCl plugging would not be a problem. The amount of Cl in Sechahun case was nearly same as Jalal-Abad (400-600 ppm), higher than Chadormalu and less than Gol-e-Gohar samples. However, the K content was higher than all samples (0.04 Wt. %). Therefore, the amount of evaporated K would be 2-4 times more than other samples. Since the amount of Cl and K is simultaneously higher than usual iron ores, therefore alkaline problems may be a serious prevention factor for the continuous operation of this plant. In order to solve this problem some counter-measures is suggested and discussed including cleaning system, partial dust enriched with KCl removal and variation in the materials type of involved equipment.

Jan 1, 2018

By Hideki Yamamoto, Norihiro Murayama, Junji Shibata

"Hydrothermal syntheses of zeolite from coal fly ash were carried out by using various alkali sources. NaOH, Na2CO3, KOH, K2CO3 and their mixture were applied for an alkali source of zeolite synthesis. The various physical properties of the reaction product, such as the kind of zeolite crystal, cation exchange property, surface texture and so on, was investigated through the zeolitization reaction from fly ash. The mechanism of zeolitization reaction was considered from these results.Zeolite P(NaP), hydroxysodalite(HS) and chabazite(K-CHA) are synthesized as zeolite species, when fly ash hydrothermally reacts in various alkali solutions at 393K. The crystal structure of the products obtained in NaOH solutions for 3h changes from NaP to HS with increasing NaOH concentration. K-CHA formation in KOH solutions needs 10h of reaction time, which is longer than that of NaP or HS.Dissolution, condensation and crystallization steps exist in the zeolitization reaction from fly ash, and the particle surface of products remarkably changes in each step. The fly ash is spherical particles and the surface is smooth(Fig.1(a)). The dissolution of fly ash occurs in the heating process until 393K, and the particle surface changes like unevenness(Fig.1(b)). In case of NaP, the condensation of aluminosilicate ions takes place at 373-393K, and the amorphous aluminosilicate is deposit on the unreacted fly ash(Fig.1(c)). The crystallization of NaP already begins to occur at 393K and the surface is covered with fine zeolite crystals for 24h(Fig.1(d))."

Jan 1, 2003

By William Conger, Greg Schick

Grinding media consumption is a major cost variable in industrial mineral comminution circuits. Specifically, industrial SAG media consumption results from a combination of surface abrasion wear, media breakage, surface spalling and rejection size from the mill. Three main consumption rates; weight of media consumed per time, per kWh and per weight of ore ground are defined and compared. Recent industrial data has provided an opportunity to relate consumption in terms of weight of media consumed to weight of ore ground (g/tonne) and weight of media consumed per kWh of energy consumed (g/kWh) with SAG specific grinding energy consumed (kWh/tonne). Using relationships developed from this data it is possible to project SAG media consumption in future mineral comminution circuits.

Jan 1, 2014

By R. X. Li

The overall flow-sheet of producing chromium (III) sulfate is described in this paper. The suitable conditions of each process such as sintering, leaching, aluminum removal, reduction, and de-composition conditions were experimentally studied. The results show it is reasonable to produce chromium (III) sulfate with the flow-sheet pointed out in this research work. The final product is Cr2(SO4)3 solution contained 150~250g/L Cr.

Jan 1, 2014

By B. Aydin, G. Erturk, G. Bulut

Coal is a complex material because of its structure consisting of carbon constituents and mineral matter. Flotation is readily carried out due to hydrophobic characteristic of coal. Therefore coal flotation is the most commonly used technique for fine coal beneficiation in order to acquire clean coal separating ash forming mineral matter from carbonaceous matter. In the coal flotation, floatability of coal both depends on characteristic of coal and used flotation reagent. Frothers as a flotation reagent are used to facilitate air dispersion into fine bubbles by prevention of bubble coalescence in the pulp phase, and stabilization of flotation froths. In this study, the effects of frother types and concentrations at different pH and particle size on the coal flotation were investigated. The representative sample was taken from Zonguldak, Turkey. It contains 9.1% ash and 7313 (kcal/kg) calorific value. Pine oil, Dowfroth 250, MIBC and Isooctanol were tested as frother types. It is determined that 1.92 ppm frother concentration is sufficient to float coal, except pine oil. In mixed frother tests, it is seen that Dowfroth 250 is more effective than others. No significant difference in coal recovery was observed for flotation tests at the different pH values. The best results are obtained in size of coal (-0.1 mm) with all frothers.

Jan 1, 2014

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

The specific surface area (Blain value) of iron ore concentrate entering the pelletizing plant is one of the characteristics most effective on the overall performance of the plant such as producing harder pellets, decreasing additives consumption, and decreasing energy consumption. Therefore, preparing the feed entering pelletizing plant is required. The iron concentrate entering Ardakan pelletizing plant located in Yazd province, Iran bears relatively low Blain value (approx. 1600 cm2/g) which necessitates one stage of regrinding so as to increase the Blain value to more than 1800 cm2/g. Studies were conducted and results showed that HPGR is the best regrinding equipment for increasing specific surface area. Conducting pilot plant tests on the concentrate sample revealed that specific throughput is 181 to 263 ts/hm3 and specific energy consumption is 1.6kWh to 2.2 kWh. Pilot tests also showed that one stage of grinding results in 407 cm2/g to 553 cm2/g increase in specific surface area. Based on these results, diameter of rolls, length of rolls, power consumption and grinding force were calculated to be 1.3 m, 0.9 m, 1276 kW and 13800 kN, respectively. Therefore, an HPGR with a roll diameter of 1.52 m, roll width of 1.1 m, power of 1660 kWh and a capacity of 500 t/h has been selected and implemented in Ardakan pelletizing plant. Industrial performance of HPGR and its effects on the plant study results show that limestone and bentonite consumption has reduced about 60% and 30%, respectively. Total Fe of the final pellet has increased from 65.5-65.7% to 66.2%. Cold compressive strength (CCS) and porosity of final pellets are approximately 292 kg/pl and 20.4, which are in the acceptable range.

Jan 1, 2014

By B. Das

The separation of iron values from a typical Indian iron ore slimes containing 57.2% Fe, 5.81% SiO2 and 7.05% Al2O3 by wet magnetic separation and selective magnetic coating is investigated. The iron phases, which are mostly paramagnetic in nature, have been coated with magnetite or colloidal magnetite in presence of surfactant by manipulating the surface properties of the minerals. The studies have indicated that an iron concentrate containing 62.32% Fe with 66.5% iron recovery can be obtained at medium magnetic intensity of 7.8 kG which is much less compared to normal magnetic intensity of 13 kG to14 kG required for hematite-goethite separation. The performance of this technique with respect to both grade and recovery is superior to conventional magnetic separation or flotation of iron ore slimes.

Jan 1, 2014

By J. K. Qu

As one of the key inorganic chemical industries, the chromate chemical industry has spawned extensively public concerns due to the resulted environmental pollution. The cleaner production technology for chromium compounds bases on sub-molten salt medium developed by the Institute of Process Engineering, Chinese Academy of Sciences has greatly decreased the reaction temperature and energy consumption, significantly in-creased the utilization ratio of the chromium element, and successfully achieved the comprehensive utilization of chromite resources and zero emission of chromium-containing residue. The separation process of production is the most important components in the cleaner technology. In this work, we studied two parts: the first is the removal of SiO2, Al3+ from the system and the recycling utilization of alkali metal medium through adding Ca(OH)2 and CaO; the second is to get more pure K2CrO4 crystalloid and remove K2CO3 from KOH solution through evaporation to prepare raw material for manufacturing Cr2O3 and get 50%(wt) KOH. The results obtained show that Ca(OH)2 can remove Al3+ more than CaO and has lower caustic ratio than CaO when they were added 110% of theoretic quantity. The optimal pure K2CrO4(96%) can be gained at 45 Celsius degree in 30% KOH solution and K2CO3 in 50% KOH solution could be decreased to 3.5%(wt) at 40 Celsius degree. And then K2CO3 can be causticized with adding Ca(OH)2 to recycle potassium alkali. The impure material can be re-moved and suitable raw material for manufacturing Cr2O3 can be gotten and reaction medium can be also recycled in this process technology, realizing cleaner production effectively.

Jan 1, 2014

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

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

Jan 1, 2014

By Janusz S. Laskowski

The flotation-related properties of hexanol derivatives and mono-alkyl ethers of propylene oxide, which include many important flotation frothers (e.g. MIBC, DF-200, DF-250, DF-1012, etc.) have been studied. The obtained results show that the DFI (Dynamic Foamability Index) - CCC (Critical Coalescence Concentration) plot can be used to classify flotation frothers. The frothers characterized by low CCC and high DFI values have properties of strong flotation frothers, while those with high CCC and low DFI values are more selective. The proposed frother classification system, based on simple CCC and DFI measurements, provides, for the first time, a solid ground-work for characterization of the flotation frothers.

Jan 1, 2003

By Chen Zhiqiang, Luo Chuansheng, Chen Ziqiang, Liu Jianguo, Rao Jinshan

To comprehensively utilize the valuable resource in tailings, increase the economic benefit of mine, reduce the amount of tailings, prolong the service life of tailing dam, the comprehensive utilization of tailing resource is arousing the attention of more and more mines. Research of comprehensive recovery of feldspar and silica from Cu-Mo floatation tailings has been furthered. Technology of "De-sliming-Magnetic Separation-Reverse Flotation-Feldspar and Silica Separation" has been developed to utilize the resource. Slime is removed and reagents cost is reduced by de-sliming. The specific effective collector ZL is used in gangues reverse flotation, and GZ-818 is the collector in feldspar and silica separation. The grinding operation is vital to ensure the liberation degree of feldspar and to eliminate the reagents pollution on minerals surface. To a Cu-Mo flotation tailing assaying K2O 5.22%, Na2O 2.22%, Fe2O3 1.95%, Al2O3 12.05%, SiO270.66%, superfine K-feldspar and silica concentrates can be produced. The feldspar concentrate productivity is 29.67% assaying K2O 8.99%, Na2O 2.86%, Fe2O3 0.16%, Al2O3 16.99% and SiO2 68.92%. The silica concentrate productivity is 14.20% assaying 0.17% K2O, 0.04% Na2O, 0.01% Fe2O3, 0.55% Al2O3 and 98.17% SiO2. The technology provides technological reference model for the similar mines.

Jan 1, 2014

By G. Belardi, N. Shehu, L. Passeri

"This paper illustrates the possibilities of applying what is essentially a physical soil-washing technique for treatment of soil contaminated by semi-volatile hydrocarbons in order to reduce the level of pollution to that permitted by Italian regulations.The ground around a factory producing lubricating-oil additives consists of silty-sandy soils which have long been contaminated by heavy hydrocarbons, especially branched alkyl benzenes and naphthalene derivatives. Pollution is particularly marked in some zones (hot-spots) where Total Petroleum Hydrocarbon (TPH) values are as high as 7000 ppm. The hydrogeological characterization showed the presence of a gravely soil in a sandy/silty matrix, with big stones making preferential paths to the water circulation. The permeability is 10-5 m/s and the water-table occurs at about 3 m below ground level.After laboratory and pilot-scale studies on representative samples of in-situ soils with TPH between 2700 and 7000 ppm a flow-sheet is proposed for reducing TPH values below the acceptable limits in Italy, namely 700 ppm for hydrocarbons with more than 12 carbon atoms and less than 250 ppm for those with fewer.On the basis of indications provided by laboratory tests a mainly physical treatment process of soil washing has been developed. This is used to clean-up soil from a site polluted by non-volatile hydrocarbons with a high TPH value. The process involves a high-density attrition stage followed by wet screening at 0.5 mm and then wet-gravity separation of the minus 0.5 mm fraction in the centrifugal field.The gravity separation products consist of a light fraction with particle size finer than 15 micron which contains most of the pollutants, and a heavy coarse fraction with TPH values conforming to the limits set by Italian regulations (less than 700 ppm hydrocarbons whose structure contains more than 12 C atoms, and less than 250 ppm of hydrocarbons with less than 12 C atoms)."

Jan 1, 2003

By Y. G. Sun

This paper mainly reported separation manganese silver oxidized ores process by amylum de-gradation reduction and its influencing factors. When dosage is given according to nMn : nH2SO4 : n(C6H10O5)n : nH2O=1:k21.8: k116.66:30, the amount of up to 95.93% Mn leach rate and less than 2% silver loss can be obtained. Cyanidation process was used to extracted silver from leaching Mn residues. Silver leach rate could reach 94.15% at consumed amount of 1kg/t NaCN for 1h. Silver leach recovery rate was more than 92.27% by leaching Mn and cyanidation two-step processes so manganese and silver were separated effectively.

Jan 1, 2014

By Seoul National University, Ki-Ho Kim, Jong-Pyo Kim, Sung-Min Joo, Hee-Chan Cho, Hyung-Seok Kim

Aragonite was synthesized in addition of Mg2+ ion and SrCO3 seed by carbonation process, and the best condition and mechanism of the synthesis was studied by analysis of continuous pH change, ICP, XRD, and SEM. As MgCl2•6H2O addition increased, aragonite phase increased at condition of CO2 flow rate of 100 mL/min and stirring rate of 250 rpm. It was the dissolution of Mg(OH)2 that determined overall reaction time. As SrCO3 seed addition increased at 0.2 mole MgCl2•6H2O, the amount of aragonite increased and the aspect ratio was from 5 to 9. And it was thought that Mg2+ ion prohibited calcitetransformation of aragonite formed by SrCO3.

Jan 1, 2003

By A. E. Sobolev

The kinetics of hydrochemical oxidation of antimonite in solutions of nitric acid was studied using the rotating disk method and the factor experiment design. The dependences of the antimonite?s oxidation rate on concentration of nitric acid solutions, temperature, disk rotation frequency, and duration of interaction were determined. The adequate kinetic models allowing calculating the specific oxidation rate at any combination of the values of the influencing factors were obtained. The oxidation process is found to proceed in a mixed mode, close to chemically controlled. Gradually, as the sediments of elemental sulphur and Sb2O5 accumulate on the disk surface, the process becomes controlled by internal diffusion. The observed high (more than second) order of the oxidation rate with respect to the concentration of nitric acid was explained by the autocatalytic action of the acid reduction products. The apparent activation energy depends on the stage of interaction. At the initial stage (in a mixed mode of the process proceeding), it depends on nitric acid concentration and varies from 31.5 kJ?mol?1 (in 2 M HNO3) to 36.1 kJ?mol?1 (in 10 M HNO3). This trend indicates the weakening of diffusion limitations with a nitric acid concentration increase. When the process is controlled by internal diffusion, the apparent activation energy was found to be 14.5 kJ?mol?1. The obtained kinetic characteristics enlarge the database on hydrochemical oxidation kinetics of sulphides and can be used for the elaboration of the recommendations for the effective comprehensive exploitation of antimony-bearing ores and concentrates.

Jan 1, 2014

By Chandra Sekhar Gahan

The present study aimed to investigate the depyritization of coal using iron oxidizing and sulphur oxidizing acidophilic chemolithotrophic microorganisms in an iron free 9K growth medium at varying pulp densities. Three different coal samples used in the shake flask study from three different countries such as domestic anthracite (Korean), Indonesian and Chinese lignite. Experiments were carried out in batch at a controlled temperature of 35 °C and varied pulp densities of 8%, 10% and 12% (w/v) with a working volume of 100 ml containing 10 ml of microbial inoculum and 90 ml of the iron free 9K growth medium. Coal samples were crushed and ground to fine size fractions <100 microns by attrition mill wet grinding. The progress in the experiments were followed by the regular measurements of pH, redox potential, viable planktonic cell count, residual Fe2+ ion concentration, amount of acid addition and amount of slaked lime addition. The pyritic sulfur removal percentage varied between 90-95% with highest sulfur removal with China coal (95%) followed by Korean Coal (93-94%) and slightly lower level for Indonesia coal (90%). However the pyrite oxidation was highest for Korean coal ranging between 78-80% followed by a similar level of pyrite oxidation of 50-61% for the Chinese and Indonesian coal. It was found that 10-12% pulp density would be fairly feasible for all the different coals tested leading to an economical process. Another benefit from this study is the iron free 9K growth medium, which will reduce the operation cost and overall it?s an environment friendly process.

Sep 1, 2012