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By Yuri Yemelianov, Stanislav Balikov, Alexander Epiforov, Andrey Boldyrev, Andrey Bogorodsky

"Test work was carried out using copper gold-bearing flotation concentrate with 6.85%Cu, 14.30%Fe, 20.70%S and 2.34%As. Gold and silver grade in the concentrate is 54.6 g/t and 92 g/t, respectively. Gold and copper are valuable components in the concentrate. Gold is partially associated with pyrite and fahlores. Copper in the concentrate can be found as tennantite (Cu12As4S13). The 71% of gold from the flotation concentrate is recoverable by cyanidation with simultaneous cyanide consumption in the amount of 96 kg/t. The major reason of refractoriness is that gold is fine encapsulated into sulfides and the presence of cyanicide-copper. The concentrate ground as much as 95% minus 10 µm was treated using low-temperature POX at the temperature of 100±5°C, L:S ratio of 5:1 and the process time of 1-5 hours. Residual sulfide sulfur in the cake is 2.28% which is 89% sulfide oxidation. The highest copper recovery to POX solution is 91%. It was found that gold recovery to cyanide solution is 85-94% during alkaline pre-treatment of POX cakes followed by cyanidation. In this case, cyanide and lime consumption is 75-90 kg/t and 120 kg/t, respectively. In order to recover precious metals from POX cakes leaching using sodium sulfite was carried out. Test work was conducted at varied reagent concentration, L:S ratio and leaching time. Gold and silver recovery achieved was 85-95% and 59-63%, respectively."

Jan 1, 2014

By Ashish Kumar

High grade ore deposits in the world are fast depleting and the valuables in the low-grade ores are finely disseminated. The feed grade to flotation circuit is also declining. Attainment of suitable grind is preferred, which inevitably creates more fines of the gangue minerals to interfere with the flotation process because of the undue competition between the fines and the valuables for the collector ion adsorption. Besides the use of polymeric or long chain hydrocarbon depressants for the gangue mineral, microbial induced flotation also has potential to float minerals selectively. Thiobacillus ferroxidans and Thiobacillus thiooxidans adhere on the minerals to modify its surface properties and affect the minerals flotation acting as depressants. Hindustan Zinc has conducted laboratory studies to understand the adhesion of microorganism on the mineral surfaces and its impact on the selective flotation. The experiments were further designed to reduce consumption of depressing reagents for graphitic carbon, pyrite, and galena. Preliminary studies reveal that desired quality of concentrate can be achieved with reasonable recovery. Keywords: thiobacillus thioxidans, thiobacillus ferroxidans, bioflotation, microbial induced flotation

Sep 1, 2012

By J. W. Ahn

Calcined calcium oxide from limestone is hydrated to manufacture calcium hydroxide, and then precipitated calcium carbonate is synthesized from calcium hydroxide. Precipitated calcium carbonate of various morphologies is obtained by controlled conditions of each step and characteristics of limestone, calcium oxide and calcium hydroxide. Especially characteristics of calcium hydroxide have the most influence on morphology of precipitated calcium carbonate character. In this study, therefore, it is investigated the specific surface area of calcium hydroxide and morphology of precipitated calcium carbonate according to hydration temperature. Calcium hydroxide hydrated at high initial temperature has larger particle size than that hydrated at low initial temperature. And formation yield of aragonite precipitated calcium carbonate has improved by using calcium hydroxide had larger particle size (hydrated at high initial temperature).

Jan 1, 2014

By A. G. Bulaev

Biohydrometallurgical technologies based on activity of acidophilic microorganisms oxidizing ferrous iron, sulfur, and sulfide minerals are widely used to extract base and noble metals from sulfide ores and concentrates. As sulfide minerals oxidation is exothermic, industrial processes are usually preformed at 40–50°C. Moderate thermophiles predominate under these conditions. Most of moderately thermophilic acidophilic microorganisms that oxidize metal sulfide are mixotrophic, i.e., they use both organic nutrients and CO2 as carbon sources. Carbon availability is crucial for microbial activity and affects efficiency of biohydrometallurgical processes. Aeration with CO2-enriched air is often used to increase microbial activity in biooxidation reactors. Organic nutrients can be used as alternative carbon source for moderately thermophiles performing biooxidation of sulfide concentrates. We performed several experiments with different sulfide concentrates to study effects of organic carbon sources on biooxidation efficiency and demonstrated that application of such organic nutrients as yeast extract (YE) and molasses made it possible to increase biooxidation efficiency. For example, addition of 0.02% YE in the nutrient medium increased biooxidation rate of pyrite–arsenopyrite gold bearing and chalcopyrite concentrates in batch mode at 45°C. YE addition increased oxidation rate of sulfide sulfur and gold recovery level from 65 to 87% and from 73 to 81%, respectively. Similarly, YE addition increased copper extraction from 47 to 54%. At the same time, YE addition increased efficiency of biooxidation of pyrite–arsenopyrite gold bearing concentrate in continuous mode. Without YE addition, oxidation rates of pyrite and arsenopyrite were 65.7% and 94%, while gold extraction was 71%. YE addition (0.02%) made it possible to oxidize 74% and 95 % of pyrite and arsenopyrite and extract 78% of gold. Addition of molasses (0.02%) similarly affected biooxidation efficiency. Thus, addition of organic nutrients in nutrient media is a promising strategy for improvement of biohydrometallurgical processes.

Jan 1, 2018

By John Starkey

"The development of the SAG Power Index (SPI) Test in Canada has created a new and accurate way to measure ore hardness in a SAG environment. Coupled with the standard Bond Ball Mill Work Index Test it is now possible to determine from these two relatively inexpensive laboratory tests, the amount of energy required to grind an ore from the primary crushed size to the desired liberation size. By testing multiple samples to discover where the hard and soft ore zones are located, the representative hardness distribution for the ore body can be determined and grinding equipment selected that is capable to meet production targets for all mining areas of the deposit.Previously, it was deemed prudent to select up to 50 t samples of ore for Semi Autogenous Grinding (SAG) pilot plant tests and a second 5 t sample for metallurgical pilot plant work. The methods outlined in this paper show how the 50 t sample is no longer required for SAG design because it is better to measure the representative hardness distribution of the ore body than the hardness of a “chosen” representative sample. This is demonstrated to be true by the fact that the lower horizons of an ore zone cannot initially be accessed to recover 150mm pieces, and the bulk samples taken, rarely represent the desired design hardness of the ore. Median hardness will not yield a good result in most cases and a clear understanding of the location and extent of the hardest zones is imperative to achieve a truly successful grinding circuit design.This paper discusses two plants (Kubaka and Agnico Eagle) that have been designed using SPI and Bond with no pilot plant test backup. Both have been very successful in that they can grind design tonnage on the hardest ores in the mine. This guarantees that the mine’s profitability is protected in any mining sequence. It also allows the extra power to be converted to higher throughput on softer ores if additional cash flow is needed. The advantages from the owner’s point of view are dramatic. This procedure will be attractive as well when considering the costs for test work, and the samples for testing. Existing diamond drill core is normally used and this allows the inclusion of data from the deepest regions of the mine. In addition, it is also clear that the decision to use a crusher can now be made at the design stage of a project based on measured parameters and the estimated capital costs of alternative designs."

Jan 1, 2003

By Sonia Helle, Ursula E. D. Kelm

"From a metallurgical point of view, acid leaching of oxide zone copper ore is considered in the first place in terms of ore grade, whole rock mineralogy, rock granulometry, crushed aggregate size distribution, porosity, permeability and corresponding fluid flow characteristics. Despite exhaustive physicochemical and general mineralogical characterization, drops in copper recovery occur and are often attributed to and “unquantified mineralogical misbehaviour” of the gangue phases. This study establishes an experimental link to monitor and quantify the chemical interaction of chrysocolla, malachite and atacamite with reactive gangue phases.Laboratory-scale sulphuric acid (15%) leaching in small columns is carried out using a synthetic rock composed of 57% quartz, 1% ore phase, and 42% reactive gangue. Gangue phases were selected to represent mineralogy found in argillic, advanced argillic, and propylitic alteration zones. Exotic copper ores of Codelco Norte (in particular Mina Sur) served as model for the modal distribution of mineral phases. Natural reactive gangue phases (<200 Tyler mesh) were chosen as pure as possible: Saz-1 and Swy-1 montmorillonites, KGa-1B and KGa-2 kaolinites (all Clay Mineral Society, USA, Source Clays) Nau-2 nontronite, Imt-1 illite (both Clay Mineral Society Special Clays) and Chilean mordenite, laumontite and bentonite. Ore phases are: mineraloid chrysocolla from Radomiro Tomic (Codelco Norte), reagent grade malachite and a purpose synthesized atacamite-paratacamite mixture. Complete chemical, physicochemical and mineralogical characterizations were carried out for ore and gangue phases.The following observations hold for samples with and without mineralization: Smectite-rich gangue increased up to 75% in volume. Once wet, air-filled vesicles formed due to the rapid sealing effect of overlying smectite in the column. No volume change occurred for illite, mordenite and kaolinite gangues. For kaolinite mixtures acid puddles formed on top of the column during initial leaching due to the delamination and barrier formation of this phyllosilicate. Fluid recovery was <60% for expandable phases and reached up to 80% for non-expandable mixtures. These observations confirm the very low extractions obtained in ore with a combined smectite – kaolinite gangue for Mina Sur. The most important mineralogical changes observed in the solid residues are: reduction of basal smectite phase reflections (XRD), and slight loss of illite intensities. This is also reflected in the major element composition of the residues, which demonstrate a loss of Mg, Mn, Ca, Na, K followed by Fe, Al and Si; with their proportions depending on the starting materials. Furthermore, alunogen and meta-alunogen formed, with related phases coquimbite (illite) and godichite (nontronite) also depending on gangue mineral chemistry. For laumontite samples, meta-alunogen and alunogen precipitated from the leachate."

Jan 1, 2003

By Zoran M. Stevic, Mirjana M. Rajcic-Vujasinovic, Zvonimir D. Stankovic

"Covellite is one of the most important copper sulfide minerals. Its behavior during the anodic polarization, as well as its rest potential in various solutions are of importance for flotation processes and also define the mechanism of electrochemical extraction of copper from sulfide minerals.Measurements of the rest potential have been performed in water solutions in presence of different cations and anions. The existence of the Nernst type dependence of the rest potential on the activity of some of the investigated ions was established. The biggest influence on the rest potential of covellite exhibits the change of activities of the ions forming the crystal lattice of investigated mineral, i.e. Cu(II) and S(II). The dependence of the rest potential of covellite on logarithm of Cu(II) activity has a shape of a strait line with a positive slope of 60 mV, while when concentration of S(II) anions increases ten times, the rest potential of covellite decreases about 120 mV. The first dependence was established in acid medium, while the second was registered in alkali one.Different electrochemical techniques have been used for the investigation of the behavior of covellite during anodic polarization. In the basis of all these measurements is a three electrode system consisted of: 1) working electrode made of the sample of natural covellite from the Bor mine (Eastern Serbia, Yugoslavia); 2) reference electrode (saturated calomel electrode) and 3) counter electrode (flat platinum). Electrolyte solutions used in these investigations are of the same kind as those used in the rest potential measurements. Sulfate and chloride solutions, as well as the mixed sulfate/chloride solutions, are the most perspective from the application point of view.Cyclic voltammetry has been the first used method that confirmed the formation of passive layer on the electrode surface during anodic polarization. Elementary data about the reaction mechanism have been obtained too. More detailed data needed for more precise conclusions about the mechanism and rate of the anodic process on covellite have been obtained by galvanostatic method. It was established that the essential difference exists between the reaction mechanism in sulfate and chloride solutions. Also, the difference is exhibited in the nature of reaction product directly connected with the passivation of the electrode surface. Chronopotentiometric investigations have been performed in sulfate, nitrate, chloride perchlorate and mixed sulfate/chloride solutions applying different current densities. The shape of obtained curves indicate if there was a surface passivation and how intensive it was."

Jan 1, 2003

By Y. S. Sun, P. Gao

Compared with conventional roasting and magnetic separation processes, higher reduction temperatures and stronger reducing atmospheres are used in reduction technologies to reduce iron oxides to metallic iron, which is often liberated during reduction and amenable to magnetic separation. Reduction and magnetic separation of an Australian refractory iron ore was therefore studied as a function of reduction temperature, time, coal addition, feed thickness and size of Australia iron ore. It was found that during reduction, the particle size of the reduced iron increased with reduction temperature and time. Subsequent magnetic separation tests were further conducted on the reduction products. A reduced iron powder with a Fe grade of 85.67% was obtained at a Fe recovery of 87.82% under optimum reduction conditions where a metallization rate of 85.82% was achieved. The mechanism involved in reduction is discussed based on XRD and SEM examinations. And the results indicated that theiron minerals such as hematite and limonite in the Australian iron ore were reduced as follows: Fe2O3?Fe3O4?FeO?Fe. Furthermore, the metallic iron particles produced by reduction increased in size with longer reduction times.

Jan 1, 2014

By G. Voiloshnikov, A. Bogudlova

"The deleterious effect of carbonaceous matter during cyanidation of gold ores (so called preg-robbing) has been recognized for many years. Based on this, a new method using flotation to reduce the content of carbonaceous matter was developed. Low-sulfide gold-bearing ore with carbonaceous matter of 0.14% from a Russian deposit was processed. The purpose of these tests was to compare two flow sheet options. Option I comprised removal of carbonaceous product prior to sulfide flotation. Option II comprised removal of carbonaceous matter from flotation concentrate. It was found that the content of carbonaceous material can be reduced in sulfide gold-bearing concentrate prior to leaching. High gold recovery was observed during the separation of carbonaceous material prior to sulfide flotation using Option I. Due to lower reagent consumption the costs for reagents were decreased using Option II. The results have shown the effectiveness of a new method. Patent No. 2783808 was obtained for removal of carbonaceous material prior to sulfide flotation. This information will be used to design a large processing plant flow sheet in Russia."

Jan 1, 2014

By F. Burat

The present research covers the results of experiments carried out with high frequency vibration screen on dewatering of coal fines. In the tests, the addition of surface active reagents was studied employing a high frequency vibrating screen. To increase the efficiency of mechanical dewatering processes, ultrasonic treatment was applied along with surfactants and optimum dewatering conditions were obtained. The moisture content of the feed material was from 82.5% to 41% by the optimization of operation parameters including the angle of the screen, vibration frequency, feed rate and screen opening size. Optimum parameters obtained in dewatering processes carried out with the vibrating screen were kept constant and the effects of surface active reagents and ultrasonic treatment on dewatering were investigated. Finally, the moisture level of the material was further reduced from 41.0% to 37.66%.

Sep 1, 2012

By Gaurav Soni, Roe-Hoan Yoon

A first principle flotation model has been derived from the basic mechanisms involved in flotation. The model consists of a series of analytical equations for bubble generation, bubble-particle collision, attachment, detachment, and froth phase recovery. The model can predict flotation from both hydrodynamic and surface chemistry parameters such as bubble size, particle size, energy dissipation rate, ?-potentials, contact angles (?), etc. The model predictions have been compared with the results of a series of laboratory flotation tests conducted using mono-sized glass beads of different particle sizes and contact angles under different operating conditions. Some of the experiments were conducted using a 1:9 mixtures if hydrophobic silica and hydrophilic magnetite, so that the product graded could be readily determined by simple magnetic separation. The model predictions are in good agreement with the experimental results both in recovery and grade. A computer simulator developed on the basis of the model is capable of designing a preliminary flotation circuit on the basis of feed characteristics, e.g., size-by-liberation data, and the hydrodynamic information on the flotation cells to be incorporated in the circuit.

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 Y. J. Ferdosi

This paper presents the outcomes of the preliminary investigation focused on the potential usage of Electrochemical Impedance Spectroscopy (EIS) in minerals processing. Currently, Electrochemical Impedance Spectroscopy has been successfully employed in the characterization of multilayer structures formed as molecules adsorb on flat surfaces and is commonly used in bio-related research. Few studies have explored the application of EIS in minerals processing, particularly for mineral particles and flotation systems. In the first series of tests, the impedance response was investigated as a function of particle size, shape and hydrophobicity using model quartz particles. The particle size fractions and the shape were found to contribute to the impedance response. The more hydrophobic quartz particles resulted in a higher impedance values. Further tests involved pure sulfide minerals including chalcocite, bornite, chalcopyrite and pyrite. The AC impedance measurements were conducted as a function of collector (sodium ethyl xanthate) dosage. The AC Impedance data was modeled using the combination of reference circuits. It has been shown that adsorption of collector onto sulfide minerals surfaces results in a higher magnitude of impedance. Increasing the collector dosage resulted in an increase in AC impedance for chalcopyrite, while a decrease was observed for chalcocite. Significant variations in impedance were exhibited by bornite and pyrite with a gradual increase in collector dosage.

Sep 1, 2012

By V. V. Morozov, I. S. Barmin, A. V. Tugolukov, V. V. Polivanskaya

"It was presents the results of research on improving reagent regime and scheme of enrichment of slime classes of Apatite-Staffelite ores and tailings stockpile of Kovdorsky enrichment plant. It was investigated the regularities of flocculation in the processes of thickening and selective flotation apatite-bearing ores. It was established character of the influence of flotation reagents on the flocculation process. It was shown that the sodium silicate and soda ash have a stabilizing effect by thickening of sludges. Neonol and oleic acid have a coagulating or flocculating effect. It was tested the new regime flotation, involving an initial conditioning with using of reagent - dispersants before feeding the pulp into the flotation and subsequent conditioning with reagents having a coagulating effect. The flowsheet and reagent regime for enrichment of fine-grained tailings stockpiled was developed, which providing production of standard apatite concentrate and increasing the recovery of valuable components. There are presented results of the research of activities of strong organic surfactant on solubility of colloidal form fatty acid collector and aggregate stability of fine minerals in the process of thickening and flotation. Surfactants such as Neonol have been investigated for increasing the activity of the collectors. When using the process of thickening sludge fraction with flocculant Praestol 2540 and stadial conditioning of sludge were obtained concentrates containing up to 38.1% P2O5 at recovery. INTRODUCTION A feature of the Apatite-Staffelite ores of the Kovdorsky deposit is the presence of a large number of fine mineral particles and a reduced hardness of phosphate minerals (Beloborodov et al., 2010, Tugolukov et al., 2012). Formed in the ore-preparation process, sludges are lost with a discharge in the thickening operation. Sludge is characterized by an increased content of phosphorus pentoxide (P2O5). Losses of P2O5 at enrichment of the stale tailings of Kovdorsky GOK reach 14.0%. The high losses of P2O5 caused a profound study of the behavior of thin apatite classes under conditions of thickening and flotation."

Jan 1, 2018

By Kunihiko Yamaguchi, Gjergj Dodbiba, Toyohisa Fujita

Usually magnetic separation is performed to separate ferromagnetic, paramagnetic and diamagnetic particles by controlling magnetic field strength. In this research the wet high gradient magnetic separation at various kinds of magnetization of medium has been investigated to separate different kinds of magnetization of paramagnetic mineral particles from each other. Most of week paramagnetic particles are captured at high magnetic field using superconducting magnet. If the magnetization of fluid is larger than that of paramagnetic particle, the paramagnetic particle cannot be captured in the direction of magnetic field. The paramagnetic particles of different magnetization such as hematite, chromium oxide, perovskite and rutile are separated in different magnetization of fluids. These particles are present in the incinerated bottom ash. The separation is useful to recover titanium oxide from bottom ash and the removal of chromium of bottom ash is important to reuse the bottom ash as cement. The used fluids are paramagnetic liquids dissolving paramagnetic salts and the water based magnetic fluid dispersing the stable ultrafine magnetite. The dispersion condition of particles related to zeta-potential of the suspension feed is also important to separate effectively by controlling pH

Jan 1, 2014

By M. Kanuchová, J. Briancin, M. Achimovicová

"Faculty of Mining, Ecology, Process Control and Geotechnology, Technical University, Košice, Slovakia An industrial eccentric vibratory mill was used for direct and short-time mechanochemical reduction of ilmenite concentrate (FeTiO3) and anatase (TiO2) with magnesium metal powder in order to reduce Fe and Ti resp. and hereby to convert them to the more soluble phases suitable for further hydrometallurgical processing. X-ray diffraction analysis of FeTiO3 after 60 min of milling with Mg confirmed the presence of Fe0 and Mg2TiO4 phases and for TiO2 after 180 min of milling the new TiO and MgO phases have appeared. X-ray photoelectron spectroscopy has detected Fe0 (metal) and Mg2+ species which are corresponding to the product of FeTiO3 mechanochemical reduction. The product of TiO2 mechanochemical reduction has revealed XPS spectral lines corresponding to Ti2+, Ti4+ and Mg2+ species on its surface. Morphology of mechanochemically reduced samples was studied by scanning electron microscopy analysis. Subsequent leaching of mechanochemically reduced FeTiO3 and TiO2 was performed in dilute HCl and H2SO4 at 80oC and compared with mechanically activated samples. The recovery of Ti has reached 100% for FeTiO3 and 79% for TiO2 after 60 min of leaching. Based on this study the flowsheet for possible processing of natural refractory titanium ores patented by author was adapted and documented. INTRODUCTION Ilmenite (FeTiO3), along with rutile (TiO2) represents the most important titanium resource necessary for titanium industry, for production of titanium metal, alloys and pigment grade TiO2 which are becoming more important and versatile for various industries such as an aircraft and aerospace, navy, chemical, automotive, medical and offshore wind industries, for machine and plant engineering and architecture as well, mainly due to high corrosion resistance. Pigment grade TiO2 is utilizing in pigment, plastic, glass, paper and rubber industries (Zhang, 2011). There are obvious research efforts for development of the potential alternatives to the expensive thermo-chemical commercial processes of titanium raw materials processing. Zhang (2011) has summarized conventional thermo- a electrochemical processes which involved a combination of pyrometallurgical, hydrometallurgical and electrometallurgical technologies and highlighted the improved hydrometallurgical routes promising for commercial application in the future. Such improvement could also be mechanical activation of FeTiO3, TiO2 by high-energy milling which causes their structural disordering, the changes of physical and chemical properties, consequently and has a positive effect on the dissolution kinetics (Achimovicová et al., 2014a, 2017, Baláž, 2008). The various types of mills such as a planetary ball mill, a vertical ball mill, a drum mill, an attritor were used for mechanical activation of FeTiO3 as a pretreatment process for subsequent leaching (Achimovicová et al., 2014)."

Jan 1, 2018

By Hong Nguen Vu, Pavla Ovcarí, Peter Fecko, Barbara Tora

The aim of this paper is to evaluate the suitability of a coal sample from the mine Jaworzno (Poland)- locality for bacterial leaching. Laboratory research used a pure bacterial culture of Thiobacillus ferrooxidans. The results showed that bacterial leaching was effective, with a one month leaching time, when 65% of total sulphur and 85% of pyritic sulphur was leached. The paper describes changes to the pyrite during and after bacterial leaching.

Jan 1, 2003

By Chuanyao Sun, Longli Liu, Fayu He, Guiye Wu

Utilizing thioglycolic acid (TGA) as a template and using structure-guided design, a molecular modelling approach has been used to design and screen appropriate dispersant for chalcopyrite. A series of organic dispersants based on a TGA substitution with hydroxyl and amino and sulfonic functional groups have been examined on chalcopyrite surface. 20 organic depressors of chalcopyrite have been investigated to study the quantitative structure-activity relationship (QSAR) of chalcopyrite depressors. For the chalcopyrite surface, depressor containing carboxyl and sulfonic group is generally stronger than the depressor containing hydroxyl group. Increasing the number of hydrophilic group can effectively enhance the inhibition. Increasing the number of Solidophilic group does not necessarily lead to enhanced inhibition ability; steric factor is one of the important factors to affect the interaction. Extension alkyl carbon chain length cannot enhance the interaction of depressors. Isomers principle as well as applies to the chalcopyrite depressor molecular design. Flotation verification tests further confirmes the accuracy of the molecular simulation. Through the Computer Aided Molecular Design (CAMD) technology, we can save enormous time and resources to design novel surfactants. This research and application will play a great significance role in sulfide flotation.

Jan 1, 2014

By Irena Grigorova

"Vermiculite is a naturally occurring mineral compound composed of shiny flakes, resembling mica. Worldwide, vermiculite has been used in various industries since 1920. When heated to a high temperature, flakes of vermiculite expand several times their original size. The expanded vermiculite is a lightweight, fire-resistant, absorbent, and odorless material. These properties allow vermiculite to be used to make numerous products, as an additive, for example to potting soil, in agricultural, construction, horticultural and industrial applications, including pesticides, insulation, potting mixes, brake pads, sound deadening materials, fire protection, paints, sealants, insulating concrete and etc. Over recent years researchers have been looking for effective economic and environmental methods and solutions for fine technological waste utilization. As a result of vermiculite ore processing large quantities of fine waste dust are formed. Until now there has been no application for this waste product. Currently this waste product is stockpiled using valuable land space, and is a potential contaminant. The paper presents the results of a study on the possibility to obtain briquettes from fine vermiculite by-product. The particle size distributions, chemical and mineralogical compositions of vermiculite were determined. It was established that consolidation of vermiculite dust by methods of briquetting and its consequent application in agriculture as meliorants for physico-chemical treatment, improves soils aeration structure and properties."

Jan 1, 2014

By Yu. E. Emelyanov, A. V. Bogorodsky, R. N. Nabiulin, S. V. Balikov

"The paper describes the results of the study of gold-copper flotation concentrate atmospheric oxidation at different sizes of material, varying oxidation time, with air or oxygen blow. The study showed the low rate of sulphide oxidation during oxidation of flotation concentrate at a feed size (P98 -74 µm). The coppery recovery into solution was 48%; the recovery of gold by subsequent cyanidation reached 86%. Preliminary flotation concentrate grinding to P98 -20 µm provided oxidation of 90% of copper minerals, 80% of arsenopyrite and 15% of pyrite. The gold recovery by atmospheric oxidation of a fine-ground flotation concentrate increased by 59%, from 36% to 95%, the NaCN consumption reduced by 21 kg/t, from 30 to 9 kg/t. INTRODUCTION Processing of sulphide gold-copper ores and concentrates using conventional cyanidation technology results in higher reagent consumption and lower gold recovery. Destruction of sulphide minerals and extraction of copper from a processed product prior to cyanidation is essential for improving efficiency of precious metals recovery and reducing main reagents consumption. Atmospheric oxidation (AO) is one of the most promising hydrometallurgical methods of refractory gold-copper concentrates processing, along with biooxidation and pressure oxidation. The nature of this approach lies in oxidation of sulphides at 90-95°C, in acidic or alkaline conditions, with bubbling of oxygen or air, after preliminary ultrafine grinding (1-4). The following reactions of sulphide oxidation occur during atmospheric oxidation of a gold-copper flotation concentrate. Pyrite is oxidized with the formation of ferric sulphate (1) and elemental sulphur at low temperatures (2), whereas some portion of elemental sulphur reacts to form sulphuric acid: FeS2+3,75O2+0,5H2O=0,5Fe2(SO4)3+0,5H2SO4; ?G=-1144,02 kJ/mol (1)"

Jan 1, 2018