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By Bo Feng

The development of surface charge of serpentine mineral and implications for sulphide ?otation have been studied through flotation tests, sedimentation tests, zeta potential measurements and optical microscope photos. The results show that the serpentine mineral was positively charged at an extensive pH range, with an isoelectric point (IEP) of 11.9. The magnitude and sign of the pyrite particles were pH dependent and were negative for pH values above 2. At pH value 9, where ?otation of nickel sul?de ores is routinely performed, serpentine and pyrite particles attract through an electrostatic mechanism. Slime coatings of serpentine adhere to the surface of pyrite, reducing pyrite flotation recovery. The removal of magnesium ions from the serpentine surface by acid leaching results in a decrease of serpentine IEP and eliminates the adverse effect of serpentine on pyrite flotation. Therefore, it has been clearly established that the surface charge value developed in the serpentine/aqueous electrical interface is a function of the serpentine surface incongruently dissolution. As a result of hydroxyl dissolution, the magnesium ions are left in serpentine surface, which is responsible for serpentine surface charge. The methods, which can remove magnesium ions from serpentine surface, can be used to eliminate the adverse effect of serpentine on pyrite flotation.

Sep 1, 2012

By Jyotirmoy Sarma

The surface-active agent, like sodium humate, in the present systems produces a very stable suspension. Saline water up to 15% is used as a flocculating agent for recovery of water from the dispersed phase containing 1% solid. The recovered water in the presence of humate at different concentrations (0.05-0.2%) and at pH 8 also produces a stable dispersed phase of iron ore fines and tailings. The beneficiation techniques adopted in the present systems can increase ~ 2-3% iron value in the concentrate of iron ore fine, however, for tailings the increase in iron value is not observed. Keywords: beneficiation, flocculation, iron ore fines, tailings, saline water, surface-active agent

Sep 1, 2012

By K. Saberyan

In this study, solvent extraction of zirconium by using triphenylphosphine oxide as extractant has been investigated. The results showed that extraction of zirconium by triphenylphosphine oxides in nitric acid and hydrochloric acid media were negligible. Extraction of zirconium in acetic acid media with concentration of 0.01~0.2 M has been studied and the results showed that the maximum percent of zirconium extraction was 40% in acid acetic with concentration of 0.01 M. By addition complexing agents such as potassium thiocyanate with the concentration of 0.01~0.2 M zirconium extraction increased up to 86% in 0.2 M potassium thiocyanate. By addition of sodium salicylate with concentration of 0.01 M and in pH=2.5, the maximum extraction of 96% was achieved. The striping of zirconium from organic phase can be carried out by 0.5 M solution of sulfuric acid.

Jan 1, 2014

The major components of sylvinite ores, sylvite (KCl) and halite (NaCl), are separated by flotation. Since both these minerals are water-soluble, the process is carried out in a saturated brine, 6~7 mol/L aqueous solution of NaCl and KCl. C16~C22 primary amines, utilized as a collector, are practically insoluble in water. In commercial potash ore flotation operations these amines are melted by heating up to 70~90°C. They are then neutralized with hydrochloric or acetic acids, and such a hot emulsion/dispersion is introduced to the flotation pulp (which is at room temperature). This is immediately accompanied by the appearance of a white precipitate in the system. As our measurements indicate, the Krafft point of dodecylammonium chloride in concentrated electrolyte solutions is much higher than 80°C, and the Krafft point of C16~C22 amines is substantially higher than that. Introduction of a hot amine emulsion into a pulp, at temperature much lower than the Krafft point for the utilized amines, must cause precipitation of the amines. Some of these species are obviously flotation-active. It is interesting to observe that in summertime, when temperatures are high-er, longer chain amines perform better. It demonstrates that the colloidal amine species that precipitate serve as active species in the potash flotation. Therefore, at higher pulp temperatures, when the temperature difference between the pulp temperature and the Krafft temperature of the utilized amine is not sufficiently large, a longer chain amine, the amine with a higher Krafft point, is more efficient. The results reveal that premixing of an alcohol such as MIBC (common frother) with the amine significantly improves flotation performance of the amine. In the presence of such an alcohol the amine disperse system becomes less turbid, and the rheology of the system less non-Newtonian. All this indicates that MIBC, which does not operate as a frother in a potash flotation system, when used as a co-surfactant, enhances the dispersion of the amine colloidal system. The appearing colloidal species perform as an active form of the collector.

Jan 1, 2014

By P. Vijay Kumar

Phosphate minerals are conventionally concentrated by flotation process using soap or soap- light diesel oil emulsion as collector. Some plants use detergents such as sodium petroleum sulfonate or alfa olefin sulfonate to enhance efficiency of soap flotation. It is reported that urea a known hydrotrope enhances flotation efficiency of soap as efficiently as alfa olefin sulfonate or linear alkyl benzene sulfonate at bench scale tests. In the present study tri sodium citrate also a known hydrotrope is tested as promoter in the flotation of phosphate mineral from Eshidiya ore.

Sep 1, 2012

By M. Nonaka

An attempt to produce fuel from biomass waste by hydrothermal treatment has been made with expectation to effectively utilize a renewable source of energy and an unexploited energy resource. In this paper, we have used empty fruit bunch (EFB) that is a residue after recovery of crude palm oil from palm oil trees in a plantation in a tropic country. A hydrothermal treatment was conducted using a 500 mL autoclave, with alkali (K2CO3) catalyst. EFB was decomposed more by alkali catalyst of lower alkali content and rather polymerized in higher catalytic region. The functional group composition of the solid phase oil is similar independent of alkali content, however its burning characteristic became more incombustible with increasing alkali content.

Jan 1, 2014

By Sravya Kosaraju, Christian Ekberg, Stefan Allard

Li-ion batteries are now used in electric vehicles (EVs), plug-in hybrid vehicles (PHEVs) and, hybrid electric vehicles (HEVs). Nanostructured Li(NiyMnzCo1-y-z)O2 is one of the more popular cathode chemistries for automotive Li-ion battery, due to its enhanced properties such as large surface area, short diffusion length, enhanced ionic and electronic conductivity, improved mechanical strength and structural integrity [Pan et al, 2013]. Recycling of Li-ion batteries helps to mitigate environmental effects of virgin metal extractions along with improper disposal of end of life batteries. To fulfill these objectives of the recycling, recovery of pure streams of the involved metals should be considered. In this study, the batteries were first discharged and dismantled in an inert atmosphere (Ar). The electrodes were then heat treated in a box furnace. This was done in order to break the chains of the adhesive (PVDF) and consequently separate the metallic substrates Cu and Al from the electrochemically active compound. This heat-treatment also helped to simplify the dissolution of the metal constituents in the electrochemically active compound from the cathode in the acid leaching process. Solvent extraction was chosen to achieve separation and recovery of metals with higher purity from these leachates. In the scope of the present work, a complete process from the point of dismantling to separation of constituent metals using solvent extraction was studied.

Jan 1, 2014

By Francisco Vicuña, Miguel Becerra, Gonzalo Montes-Atenas

"The optimization of the copper recovery from smelting slag by a process of comminution / flotation has been a widely discussed topic during the last few decades. Several studies covering the characterization of different types of slag, the impact of the slag cooling rate and of different flotation operating conditions on the flotation performance have been widely published. Currently, at El Soldado mine site (Angloamerican), there are large copper bearing slag deposits that can be a profitable alternative for the concentrator with capacity to treat this material. Under this process schema, the optimization of the flotation process to obtain better copper recoveries is a relevant topic of study. The aim of this study is to assess the efficiency of a sulfidation stage of a slag and to correlate that process with copper recoveries results in a flotation circuit. This article presents a detailed examination at both laboratory and plant scales of the slag sulfidation on the recovery of copper in the flotation process. The experimental methodology involves studying the effect of the sulfidation agent dosage, the pH, the particle size distribution of the flotation feed and the conditioning time. Furthermore, the performance of the sulfidation stage was analysed through the XPS analytical technique. It was observed that the sulfidation of particles in floatable size fractions correlated well with the increase in copper recovery. The results indicated that it is possible to increase between 2 to 4 points the total copper recovery with a sulfidation process implemented appropriately."

Jan 1, 2014

By M. M. Kulkarni1

Kaolin clay is used as a filler and pigment in various applications such as paper, paint, rubber, plastics, adhesives, ink and ceramics etc. Major mineral content in crude kaolin clay is kaolinite along with some accessory minerals as quartz, hematite, mica, feldspar, anatase, rutile, illemnite etc. The Fe and Ti bearing minerals play very important role in determining quality of the kaolin, as these minerals impart yellow, pink or darker color to the white kaolin. Conventional beneficiation methods used in kaolin processing are de-gritting, classification and sodium dithionite bleaching, which improves the optical properties of kaolin, wherein reduction of color imparting constituents such as Fe2O3 and TiO2 is marginal. In the present study, these coloring impurities are separated using selective adsorption of water-soluble polymers. Degritted kaolin samples after passing through 45 micron sieve is used in the study for selective flocculation by polyacrylamide based polymers. The effect of pH, zeta potential, and polymer dose on the reduction of impurities is studied. Analytical tools such as XRF, XRD, SEM, and TEM techniques are utilized and results are discussed in detail.

Sep 1, 2012

By Yosep Han

Mechanically-induced chemical reactions between natural beach ilmenite (FeTiO3) and silicon (Si) have been examined by a combination of X-ray diffraction (XRD) and scanning electronic microscopy (SEM) analyses. The effect of various milling time on the phase transformation, crystallite size, and lattice strain of a beach sand ilmenite with silicon, and on their leaching behavior in hydrochloric acid (HCl) has been investigated. For mechanically activated FeTiO3, the crystallite size decreased and lattice strain increased monotonically with time of milling. However, the mechanochemically synthesized ilmenite with silicon showed a relatively smaller crystallite size and greater lattice strain compared with the mechanically activated ilmenite under the same milling condition. In accordance with the elapse of milling time, the intensity of both pure FeTiO3 and mechanically activated FeTiO3 gradually decreased. However, in case of the mechanochemically synthesized ilmenitereduction of FeTiO3 by silicon resulted in formation of rutile TiO2 at the milling time of 20 h and afterwards. Additional leaching experiments were carried out at an HCl/ilmenite (wt%) ratio of 20:1. The concentration of HCl was 3 M and the reaction temperature ranged from 70 to 90 oC. Mechanical activation was observed to significantly enhance the dissolution rates of both iron (Fe) and titanium (Ti) in HCl. Particularly, effects of both milling time and silicon addition on the dissolution rates of titanium and iron were significant, while those of temperature were relatively minor under the conditions investigated in this study. Keywords: mechanochemical treatment, natural beach ilmenite, silicon, leaching behavior

Sep 1, 2012

By M. Saghaeian, R. Hejazi, M. Farahani, M. Dehghani, A. Tohry

"Wet tailing dams of iron ore processing plants typically contain a significant amount of valuable minerals. In more recent years, due to the increase in iron’s prices and technological innovations, as well as the low energy consumption which required for processing of materials from tailings, dams can consider as potential valuable deposits. However, the production of iron concentrate from tailings is usually complicated where the high moisture content of the material, the high clay content and the presence of chemicals of processing such as flocculants, acids and flotation reagents, all make materials highly sticky which can be easily swollen. In the present paper, the optimization of operational parameters to recover ultrafine hematite iron ore from the wet tailings dams of the Chador-malu iron ore mine was investigated. The optimization of operational parameters, showed that with modification of the washing unit components for slurry making, the challenge of constraints from feeding the plant could be overcome. To decrease the magnetite content in the tail stream of the medium intensity magnetic separation (MIMS) and subsequently increase the efficiency, the orifice of the cleaner tail flow exit pipe was changed from 7 inches to 3 inch and yoke angle changed from 14 to 8 degrees. These changes increased mass yield by 3% and decreased the magnetite content in the final tailings to 1.2%. By recirculating the cleaner SLons of final tailings within the circuit, the solid percentage of the feed to rougher SLons decreased to around 15%, and as a result the matrices were not overloaded that easily, and mass yield increased to about 13% from 7%. All the above mentioned optimizations were achieved without significantly affecting the concentrate Fe grade."

Jan 1, 2018

By Q. J. Liu

The flotation circuit and the reagents of the all-sliming flotation about low grade and hard operation on zinc oxide ore are researched in the paper. The results indicated that there are many types of zinc minerals in this ore, and the composition is very complex. They include hemimorphite, smithsonite, hydrozincite and so on. The ore is seriously sliming. In light of the ore properties, three kinds of flowsheets have tested. They are gravity concentration (cleaning tables), flotation, combined process of gravity concentration and flotation. The test showed that the recovery of zinc is only 17.08% in the gravity separation. In combined process of gravity separation and flotation, the recovery of zinc concentrate is close to 70%. But the flow-sheet is complex and hard to control in the production. The floatation circuit is feasible. In the test, it pay attention to investigate the new combined reagent which is used in selective all?sliming flotation process. The effects of slime are eliminated by the multi-loop treatment of middling. In flotation, the final recovery of concentrate is 88.76%; the grade is 29.50%. The recovery of physical ore is 93%; and the recovery of -10mm fraction is more than 65%.

Jan 1, 2014

By Yi Ran Zhang, Nawoong Yoon, Brent Hilscher, Maria Holuszko

"Ore sorting technology has been rapidly advancing in recent years. Improving expected mill feed grade has a significant benefit to project returns, and can no longer be ignored. When there is an increase in the mill feed grade while maintaining the same throughput, the mine will be able to process much more metal and improve the floatation recovery. There are many more factors that contribute toward the economics of the project by implementing sensor-based sorting technologies covered in this paper. This paper reviews the economic impact on an underground copper-silver deposit with references to the concept of ""profit recovery,"" which is the measurement of recovery based on rock profitability rather than just metal content. The economic impact of sensor-based sorting is discussed in detail throughout the paper. The preliminary economic evaluation of the project compares the mine's base case design versus a design incorporating sensor-based sorting. The paper's primary focus is on economic impacts rather than the explanation of the sensor based sorting results. The sorting data is presented on a scoping level and using a sensor-based sorting study where the best possible results are used for obtaining the grade recovery curves. Also, the breakdown and analysis of the project economics are based on the operating cost available from the particular operation. Any assumptions taken into consideration are also outlined and discussed. INTRODUCTION The mining industry has been adopting Sensor-based ore sorting technology fairly rapidly in the recent years. The ability to increase mill feed grade by rejecting waste grade rocks early in the processing stage is proving to be revolutionary for some operations. These potential outcomes should not be overlooked by both producing operations and prospective projects, thus leading to a wide range of studies on ore sorting. The answer to this is the creation of a new term and concept - Profit Recovery™."

Jan 1, 2018

By V. A. Chanturiya

The results study the minerals oxidation were obtained by us during the methods of microscopic, FT-IR spectroscopic, XRD and chemical analyses of sulphides in tailings of copper-nickel wastes in Kola peninsula. Sulphide minerals begin to oxidize already at the stage of stockpiling and initial stages of storing. The proportion of non-ferrous metals and magnesium oxide increases with time, calcium partially precipitating in the form of gypsum. Comparison of heavy metal contents in pore solutions in cur-rent and stale copper-nickel ore concentration tailings has revealed a significant difference in practically all the parameters. The lower metal contents in current tailing pore solutions (by 5~30 times) are probably due to the presence of float reagent residues blocking oxidation. Much lower concentrations of magnesium and calcium can be accounted for by the difference in kinetics: the rate of sulphide oxidation at this stage is much higher than that of solution interaction with non-metallic minerals as the result of which the solid phase ? solution equilibrium is not achieved. It is generally believed worldwide that it the mining wastes with acidic pore solutions that pose the greatest hazard for the environment. Our findings suggest that although the solution pH in all the samples is higher than 7.8, the contain heavy metal concentrations by far exceeding permissible values. The direct determination of the total and silicate Ni contents in the tailings from current production and in storage tailings has shown that both sulphide and silicate Ni forms occur in tailings. However, the role of silicate Ni is much larger in the storage tailings. The average silicate Ni content accounts for 10% of the bulk Ni content in the current tailings and it increases to 40% in the storage tailings. Thus, the storage tailings are marked not only by sulphide oxidation and the removal of water-soluble sulfates, but also by the interaction of sulfates with the silicate matrix. Although complete equilibrium is not achieved even within 30 yr under polar-region conditions, the major part of the Ni in fine-grained fractions passes into silicate form. The probability of Ni transition to the silicate form directly correlates with the dispersion of the material and the amount of chemically reactive serpentine and hydrochlorite. The migration of Ni as sulfates and its precipitation by chemically active silicates distorts the distribution of this component in the coarse- and fine-grained fractions that are typical of tailings from the current production of copper-nickel ores. On the one hand, the variation of the mode of Ni occurrence in storage tailings lowers the value of technogenic raw materials as a source of this metal.

Jan 1, 2014

By B. Hosseini

Considering the subtractive trend of the sulfide and high-grade zinc ores in worldwide and also in Iran, Nowadays special attentions have been drawn to the extraction of zinc from its other resources such as low-grade oxide ores and secondary resources. Oxide ore of the eastern part of Mehdi-abad lead and zinc mine is silicate and has an average grade of 7% (with cut off grade of 4%). Main mineral of the Mehdi-abad ore is Hemimorphite and this mineral is associated with Goethite, Hematite, Ferrous Dolomite, and Manganese oxide mineral so that oxides of Iron, manganese and silica include almost 50% of the total ore. In this paper, the results obtained from the leaching kinetic study of the low-grade zinc oxide ore using Sulfuric acid are presented. The effects of particle size, reaction temperature, acid concentration, and solid percent on the dissolution rate have been investigated. The results obtained from the Taghochi approach showed that the zinc recovery is about 78% under the following optimized conditions: particle size: 106µm, leaching time: one hour, temperature: 45°C, acid concentration: 15% and solid percent: 15%. Kinetics study was revealed that zinc minerals leaching controlled by diffusion rate through the product layer during leaching time with the activation energy of 5 KJ/mol and compliance with the 1- (2/3. x) ? (1- x) 2/3 = k. t model. Keywords: leaching kinetics, kinetics models, sulfuric acid leaching, taguchi methods, low grade zinc ore, mehdi-abad mine

Sep 1, 2012

By S. S. Indi, D. Santhiya, S. Subramanian, K. A. Natarajan

The interaction of sphalerite- and galena-adapted Bacillus polymyxa (B. polymyxa) cells with sphalerite and galena has been investigated through adsorption, electrokinetic and flotation studies. The amount of sphalerite-adapted cells adsorbed onto sphalerite and galena is found to decrease with increase in pH. On the other hand, the adsorption density of galena-adapted cells onto galena shows a feeble maximum around pH 8, and the amount adsorbed is marginally higher in the pH range of 8 . 11.5. In the case of sphalerite the amount adsorbed is higher in the pH range of 5 to 7. The adsorption density of both the adapted cells is higher for galena vis-à-vis sphalerite. Electrokinetic studies indicate significant surface chemical changes on the chosen sulphide minerals and the bacterial cells, consequent to microbe-mineral interactions. Selective flotation tests on a synthetic mixture of galena and sphalerite confirm that sphalerite could be preferentially floated from galena, using galena-adapted cells, but not with the sphalerite-adapted cells. The cells adapted to galena assay a higher polysaccharide content and are more hydrophilic, while the sphalerite-adapted cells have a higher protein content and possess greater hydrophobicity. Transmission electron microscopic studies have provided evidence in support of the differences between the cell surface characteristics of sphaleriteand galena-adapted cells. Possible mechanisms of interaction between the minerals and the bacterial cells are discussed.

Jan 1, 2003

By M. K. Aydogan

Today, arsenic has become a much greater problem than before because of the limitations introduced by WHO and USEPA that are lowered from 0.05 ppm to 0.01 ppm. In the nature Arsenic is mostly found as inorganic compounds in the forms of arsenite (As+3) and arsenate (As+5) in aqueous solutions. Arsenic contamination in ground and surface waters has been encountered in almost every country. This element has a carcinogenic effect and can occur in natural sources and anthropogenic sources such as metal mining, groundwater usage and industrial activities. In this study adsorbing colloid flotation was applied in the presence of aluminum sulfates. In the experiments SDS and K-Oleate were used as collectors while MIBC was the frother employed. The effects of collectors and aluminum/arsenic ratios on the removal of arsenic were examined under various pH values. It was found that arsenic removal enhanced with increasing aluminum concentration. Furthermore, it was observed that pH was a very critical parameter in all experiments. The best results were obtained when initial As: SDS: Al concentrations were 10:40:40 ppm at pH 5.5. At this concentration, the efficiency of arsenic removal found to be 99.9%. Keywords: arsenic, adsorbing colloid flotation, aluminum sulfate

Sep 1, 2012

By A. Zangooi

Frothers play major roles in flotation through interaction at the air/water interface. A method of determining frother adsorption density (coverage), i.e., the number of molecules per unit of interfacial area of bubble surface, is introduced. The technique is based on mass balancing the frother around a continuously operated bubble column. The mass balance requires collection of bubbles before they burst. The column design and operating procedure is reviewed, and some preliminary results discussed. Keywords: flotation, colorimetric frother analysis technique, frother mass balance, coverage

Sep 1, 2012

By N. Syna

The selection and preparation of activated carbon suitable for specific application can often involve exhaustive adsorbent preparation and testing. This work examined an emerging technique based on modelling the correlation of observed adsorption capacity to the carbon characteristics as a means of decoupling the roles of carbon textural and surface chemical properties. The insights to these specific roles are then used in tailor-making adsorbents and in establishing the optimal carbon properties for specific application. In this study, a series of activated carbons prepared from bagasse by physical and chemical techniques and commercially available carbons were used in developing the models. These carbons were tested for the adsorption of thiourea-gold (I) chloride complexes. Thiourea is an important alternative gold lixiviant with the potential to address current ecological and safety concerns in the extraction of gold. A four-component model, which correlated the adsorption gold capacity to carbon textural and surface chemical properties, was proposed. The model fit was assessed using multi-linear regression and a partial F-test. This was followed by goodness of fit test achieved through r2, adjusted?r2 and mean square error (MSE) values. The results suggest the adsorption of the gold-thiourea complex is strongly influenced by the internal surface area and pH of the carbon. Tailor-made activated carbon from bagasse showed adsorption gold capacities of up to 198 mgAu/g adsorbent, demonstrating the potential of bagasse as a precursor for gold adsorbents and of this empirical modelling approach in developing adsorbents for metal recovery.

Jan 1, 2014

By D. Moradkhani

The objective of this research was, to evaluate the hazard of heavy metals in the soil around the National Iranian Lead & Zinc (NILZ) Company. In this study, 38 samples of soil around the NILZ factory were collected using standard sampling method, so that, the heavy metals Pb, Zn, Cd and Cr have been evaluated. The concentration of heavy metals were measured and compared with standard limits. The results show that the hazard of heavy metals in soil is not so serious and the content of Pb in just 5 percent of samples, and the content of Zn in just 3 percent of samples were above standard limits and the concentration of Cd and Cr were under the standard limits. Average, variance and standard deviation of the elements are calculated and with due attention to the standard deviation, Pb and Zn are seen to be more distributed than Cd and Cr. Also the isograde curve of heavy metals was drawn using software called Surfer. These curves showed that the heavy metals are concentrated at particular distances from the factory. Keywords: heavy metals, remote sensing, sampling method, isograde curve, Surfer software

Sep 1, 2012