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By E. V. Koporulina, E. L. Chanturiya, M. V. Ryazantseva, E. S. Zhuravleva

"The morphology of the surface of sphalerite, galena and chalcopyrite and the adsorption of butyl xanthate under conditions of preliminary treatment of minerals by the products of water electrolysis were studied using atomic force microscopy (AFM) and Diffuse Reflection Infrared Fourier Transform Infrared Spectroscopy (FTIR). It was determined that practically all types of treatment by electrochemically modified water (a product of non-diaphragmatic treatment, anolyte and catholyte) lead to an increase of surface roughness of the studied minerals due to formation of small rounded shape particles. In contrast to that, after treatment of chalcopyrite by anolyte, its surface becomes smoother. Various effects of treatment by the water electrolysis products on the adsorption of chemical and physical forms of butyl xanthate on the studied sulfides were established. As a result, the efficiency of the complex of AFM and FTIR methods, as one of the ex-situ approaches for monitoring the surface state of sulfide minerals and direct investigation of BKx adsorption products was demonstrated.INTRODUCTION In mineral processing, copper-zinc sulfide ores are one of the most complex products in view of their mineral composition, fine dissemination, complex inter-growth and the proximity of the technological characteristics of copper, zinc and iron sulfides. For the most complete disintegration, fine grinding of ores to a size of 0.074-0.044 mm is necessary. Consequently, the main method for processing of such ores is flotation, which bases on the difference in physical and chemical properties of the mineral surfaces, in particular, degree of wettability. The separation of copper and zinc minerals and their separation from ferrous and other sulfides, sulfosalts and rock mineral is a very difficult task (Chanturiya, 2000). For the successful separation of copper and zinc minerals in the appropriate selective concentrates, it is necessary to find conditions for the most complete liberation of ore and rock-forming minerals and for increase the contrast in physical and chemical properties of their surfaces. Despite significant progress in the processing of copper-zinc sulfide ores, the problem of the selectivity of the separation of the main ore minerals has not yet been fully solved and requires innovative approaches (Chanturiya, 2015). To date, various methods of preliminary energy processing of complex ores are used: magnetic pulse treatment, impact by high-voltage nanosecond pulses, electrochemical effects (including products of water electrolysis (Chanturiya et al., 2014; Bunin et al., 2015; Chanturiya et al., 2014a; Chanturiya et al., 2016), processing with flotation reagents, etc. Electrochemical treatment of water in various modes allows to obtain products of electrolysis with different oxidation-reduction properties: acid anolyte with a high oxidation potential and dissolved oxygen content, an alkaline catholyte with high reducing properties and a product of non-diaphragmatic treatment with enhanced reduction properties."

Jan 1, 2018

By M. Minagawa, G. Granata, C. Tokoro, T. Kato

"In this work, we studied the mechanochemical activation of chalcopyrite by vertically stirred ball milling (VSBM) to enhance the dissolution of copper. By using x-ray diffraction (XRD) and laser diffraction particle size analysis, we investigated the effect of milling and milling conditions on particle size and phase composition of the chalcopyrite concentrate. To elucidate the efficiency of VSBM towards the mechanochemical activation of chalcopyrite, we also conducted leaching experiments in sulfuric acid-ferric sulfate media. Under all investigated milling conditions, the VSBM determined a dramatic decrease of particle size from over 100 µm of P80% up to about 13 µm. Furthermore, the XRD of the ground chalcopyrite specimens highlighted a partial oxidation of the mineral. In leaching, upon grinding by VSBM, the increase of copper extraction ranged from a minimum of +10% to a maximum of +40%, depending on the grinding conditions. In order to elucidate whether the dissolution enhancement was a consequence of the decreased particle size or of an induced mechanochemical reaction, we performed leaching experiments on activated and non-activated chalcopyrite sample having the same particle size. In addition, we determined the activation energy of leaching before and after vertically stirred ball milling. The leaching results on samples with the same particle size highlighted a greater copper extraction and higher dissolution rates upon mechanochemical activation. Whether performing grinding by VSBM or not, the leaching kinetics was found to be controlled by the chemical reaction on the surface of the chalcopyrite particle. By grinding the chalcopyrite concentrate by VSBM, the activation energy of leaching slightly decreased from 66 to 58 kJ/mol. INTRODUCTION Due to the increasing demand of copper, low grade ores and refractory minerals like chalcopyrite are expected to become the main copper source in the next years (Klauber, 2008). As a low-grade sulfide, chalcopyrite shall be processed hydrometallurgically. However, due to the formation of a protective layer of elemental sulfur during the oxidizing leaching, the dissolution of copper is slow and/or incomplete (De Bernardi and Carlesi, 2013). Therefore, the development of new technologies to enhance the extraction of copper from chalcopyrite is highly required."

Jan 1, 2018

By G. Venkateswara Rao

The multi-gravity separator (MGS) is a novel piece of equipment for the separation of fine and ultra-fine minerals. However, the published literature does not demonstrate its use in the separation of Iron ore fines. Therefore, an attempt was made to study the effects of different process variables on the performance of an MGS for the beneficiation of Iron ore fines. The results obtained from this study revealed that among the parameters studied, drum rotation, amount of wash water and angle of inclination play dominating roles in controlling the yield and grade of the Iron ore. The majority of the newly developed Multi gravity concentrators have tremendous potentials for various applications. Therefore, the performance evaluation of these concentrators treating various minerals, coals, heavy metal recovery from tailing dams, etc., have become an active research topic. Several attempts have also been made to develop appropriate mathematical models of individual concentrators. Despite all these efforts, these concentrators have yet to find the widespread applications they deserve. The ?as received? sample assayed 40.80% Fe, 40.90% SiO2,0.24% Al2O3and 0.20 % LOI and all other trace elements within the specified range. The current paper deals with the Mineralogical studies, characterization and process amenability studies of Sub grade Iron ore from Deposit No. 5, Bacheli complex of Bailadila using Multi Gravity Separator (MGS).

Sep 1, 2012

By A. I. Arol

Bentonite is an important industrial mineral with very wide application areas. Its unique colloidal, swelling, thickening and adsorption properties make it a useful agent in drilling, metal casting, and iron ore pelletizing, environmental, food, cosmetics, pharmaceuticals and many more industries. Because of its swelling property, bentonite suspensions can only be prepared at rather low solid coentrations, i.e. 8-10%. In order to process bentonite in slurries with high solid content, it was thought that a non-polar organic solvent, instead of water, can be used. Not only large amounts of bentonite can be dispersed in organic solvents but also the solvents may be regenerated. The bentonite obtained through such a process must either equal or better properties than those of untreated bentonite. In this study, the effect of organic solvents such as acetone, methyl-ethyl ketone and n-haxane on the main properties of bentonite, such as water adsorption and rheology, was investigated. It was found that bentonite can be dispersed in the mentioned organics in large quantities with no loss of quality. Keywords: bentonite, montmorillonite, water adsorption, industrial minerals

Sep 1, 2012

By Yimin Zhu

This paper introduces the sixteen mappings and rules of mineral flotation and the subgroup, period etc in periodic table of chemical element to provide mineral flotation workers to refer in theory and practice research. the nine mappings and rules of mineral flotation and the subgroup, period are Saline minerals including the first main groups and collectors of aliphatic acid and aliphatic amines, Minerals including the second main group elements and collector of aliphatic acid, Hydrated ion of the second main group elements and quartz flotation, The floatability of oxidized minerals including the four main group elements, Organic acid including the fifth main group elements and wolframe, tin flotation collectors, The floatability of sulfide minerals including the fifth main group elements, Inorganic compounds including the seventh main group elements and mineral flotation regulator, Oxidized minerals including the forth Subgroup elements and organic flotation agents with phosphorus and arsenic, Oxidized minerals including the fifth subgroup elements and organic floating agents including the fifth main group elements, Minerals including the first subgroup elements and CN-, Sulfide minerals including the second subgroup elements and CN-, The effect of the highest N-valency inorganic acids or salts including p area elements of the third period in mineral flotation, Oxidized minerals including transition elements of the forth period and 3# flocculating agent, The floatability of minerals including elements of the sixth period, Element area of generating compositions and the collecting theory of mineral flotation and so and. Keywords: mineral flotation, periodic table of chemical element, subgroup, period, regulator, coordination chemistry

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 Fedotov. K. V., A. Y. Senchenko, V. A. Chanturiya

"The paper describes an efficient process to treat the ore from the largest in Russia copper deposit – Udokan. The recommended process is universally applicable to Udokan ores different in composition and allows reaching high copper recoveries during production of high-grade cathode copper and sulphide concentrate with 45% copper content. There are several promising trends for the process optimization and in the case they are implemented, economics of the whole project could improve significantly. One of the most important optimization options implies reduction of specific energy consumption in the course of comminution operations. Another possible option to optimize the already selected process flowsheet is production of cathode copper from sulphide concentrate directly at a mining and metallurgical plant without sending the latter to other metallurgical works.INTRODUCTIONUdokan copper deposit with resources of more than 20 million tons of copper is the largest in Russia and one of the largest copper deposits in the world. The deposit is located in Kalar District of the Trans-Baikal Territory, 30 km away from Novaya Chara railway station of the Baikal-Amur Mainline.Scientists and engineers from various research institutions have studied Udokan copper ores for years. Along the way, some conceptual process flowsheets have been proposed and each of them has its own pros and cons. The key requirement to the processes being developed was their universal application for processing of all the ore types using a single flowsheet. Due to the hard mining and geological conditions and because of complex material composition of Udokan ores it is of great difficulty to design a process which would provide for maximum economic benefits. That is why the process optimization has been ongoing until now.According to the Russian standards, the main input document for design of a metallurgical plant is referred to as a Process Design Report that covers the following key data sections: analysis of metallurgical testing results, validation of the process, design criteria, process flow diagrams, the mass and metallurgical balances, process description, equipment list and other information necessary for the subsequent design."

Jan 1, 2018

By S. Fiore, M. C. Zanetti, C. Clerici

The processes and fluxes of a cast iron foundry plant located in the North of Italy were analyzed in order to determine the amount and kind of wastes produced from the different activities. The main fractions are the molding sands, furnace muds and powders coming from the dust abatement plant, the exhaust lime, the furnace refractory, the metallic shotting and the sludges and powders coming from the dust abatement plant of molding lines for a total production equal to 800 t/d. All wastes were sampled and particle-size and chemically characterized to evaluate the best recycling or reuse solutions. Wastes were sieved and divided in three categories according to the particle-size dimensions: below 0.1 mm, between 0.1 and 0.6 mm and above 0.6 mm. The fraction above 0.6 mm dimension underwent magnetic separation to recover and quantify the potentially available iron fraction. The fraction between 0.1 mm and 0.6 mm was chemically characterized in order to understand if it could be fed to the sand regeneration plant. The below 0.1 mm fraction was characterized to evaluate the following recycling and reuse solutions: additive for molding sands and/or raw material for the concrete industry.

Jan 1, 2003

By D. Szyszka

During passing gas bubbles through mineral suspensions, some mechanical carryover of fine particles to the froth layer always takes place. The entrainment of mineral particles is influenced by many parameters, mostly by the particle size and the concentration of the frother. The paper deals with influence of selected frothers (methylisobutylcarbinol (MIBC), a-terpineol, and hexadecane tricosaethyleneglycol ether (C16E23)), common laboratory flotation frothers, on the mechanical car-ryover of quartz, a typical gangue mineral component of ores. Entrainment tests were carried out in a laboratory Mechanobr flotation machine with quartz particles suspended in aqueous frother solu-tions. The mechanical recovery of quartz in the presence frother was increasing with time and reached plateau after about 20 minutes of flotation. The plateau level of quartz recovery depended on the frother concentration. Initially an increase of the plateau with frother concentration was observed until the plateau reached the highest level called the maximum recovery emax. The emax can be used as a parameter to characterize the ability of frothers to entrainment. In the studied quartz-frother flotation system the maximum entrainment was 32%, 50% and 80% for methylisobu-tylcarbinol (MIBC), a-terpineol, and monohexadecane tricosaethylene glycol ether (C16E23), re-spectively. A comparison of the maximum entrainment factor emax with other, known from literature, indices such as bubble critical coalescence concentration (CCC), dynamic foamability index (DFI), Jw, e =25%revealed, except DFI, their similarity.

Jan 1, 2014

By K. Yoo

Cuprous oxide is one of the oldest antifouling agents and also acts as red pigment in these paints. In printed circuit board manufacturing industries, waste etchant contains a substantial amount of copper ion. In the present study, a process was suggested for recovering cuprous oxides from the waste etchant and optimum conditions were investigated to recover the cuprous oxides. The process consists of two steps: in first step, Cu powder is added into wastewater solution, and cupric ions re-duce into cuprous ions (Cu+Cu2+?2Cu+), where cuprous ions precipitate as cuprous chloride; In second step, cuprous oxide is synthesized by adding NaOH into cuprous chloride solution (2CuCl+2NaOH?Cu2O+NaCl+H2O). Optimum conditions were investigated to recover cuprous oxide in the processes. When copper powder was added into wastewater with copper ions, Cu concentration decreased from 15.6% to 2.6% and ORP decreased from 620 mV to -59.9 mV. This result shows that cupric ions reduced into cuprous ions. XRD data indicated that the precipitate was cuprous chloride powder. Using the cuprous chloride recovered and NaOH solution, cuprous oxide was synthesized. To investigate the optimum condition, various NaOH solutions were added into water with CuCl, and then pH, ORP, Cu concentration, Cu contents in precipitates were analysed. XRD data showed that main component of precipitates was cuprous oxide.

Jan 1, 2014

By Y. H. Tang

For its surface features, micro-sized hematite is usually difficult to recover by magnetic separation; especially, the existing high gradient magnetic separator in industry can not utilize collecting matrix with thin silky rods for its property of being easily blocked; the lower size limit for recovery of micro-sized weak magnetic minerals is about 0.019mm, some even is 0.037mm. This paper introduces the application of the combined new technique of water-air joint discharging of concentrate and collecting matrix with different diameter silky rods in the field of recovery of micro-sized hematite by high gradient magnetic separator. The commercial test result for recovery of a certain hematite with size about ?0.037mm shows that the recovery can be promoted by 16.81% with basically same concentrate grade.

Jan 1, 2014

By Y. M. Zhao

The dry coal preparation technology based on air dense medium fluidized bed is an innovative dry highly efficient technology of coal by introducing fluidization technology into beneficiation.. A modularized 40-60 tones/hr system (KZX-40) with an air dense medium fluidized bed separator was established. The construction cost of the modularized system is only 1/3 of the traditional wet heavy-medium coal preparation plant construction cost with the same capacity, and the consumption of dense medium can be reduced by 50%-60%. The footprint and volume of the system are decreased by 75% and by 89.81%, respectively. These facts show the improved intensity, efficiency and economy of modularized coal preparation technique. The modularized KZX-40 system can be used to separated 50-6 mm coal over a separation density range of 1.3-2.2g/cm3 depending on the variation of <1mm fine coal content. The separation efficiency of the system was investigated at low and high separation densities by float-sink experiments. The partition curve of the products at low separation density shows that the separation density (d) is 1.33g/cm3, and the probable error (E) value is 0.05g/cm3. Using 50-6mm coal with an ash content of 55.35% as feedstock, at a high separation density of 1.61g/cm3, the clean coal with an ash content of 14.67% and the tailing with an ash content of 71.26% are produced with an E value of 0.06g/cm3. It is clear that the modularized KZX-40 system is suitable for separating 50-6mm coal effectively. During the dry coal preparation process, the dust is removed by the bag collector and recycled back into the separator. So the system has the advantages to work without environmental pollution and water. The modularized system greatly reduces the construction and operating costs and decreases the area and volume required, compared with wet dense medium system. The system is applicable to the coals located in arid regions and also to the coals that tend to slime during wet separation. Keywords: modularized, KZX-40, fluidized bed, beneficiation

Sep 1, 2012

By G. V. Sedelnikova

Biohydrometallurgical studies were performed on the sulfide gold-arsenic concentrate obtained in treatment of refractory ore from a deposit located in northern Russia. Gold is disseminated in sulfides-arsenopyrite, pyrite and antimonite (their content is 10.0%, 30.4% and 0.7%, respectively). Gold extraction is only 11.8% by cyanidation. Results are given for test bacterial oxidation of the concentrate in continuous mode at temp. = 28~32°C using mesophilic bacteria and at temp. = 32~38°C using the association including moderate thermophilic bacteria. The paper shows that the use of moderate thermophilic bacteria allows to speed up sulfide biooxidation and reduce its time to 96 hours compared to leaching at temp. = 28~32°C for 110~120 hours. The optimal range of pH = 1.5~2.0 of biooxidation process was determined where bacterial solutions are produced with the molar ratio Fe:As > 3 necessary for precipitation of hard-to-solve, environmentally safe arsenical precipitates. Electron microscopy showed that sulfide biooxidation results in liberation of disseminated gold with nanoparticle-level sizes. High sorptive activity of carbonaceous matter and other compounds of bacterial residues cause low gold extraction into cyanide solution ? 28.7%. 10% resin load makes it possible to extract 88.1% Au. Aeration of pulp in calcareous medium enhances extraction to 95.7% and decreases cyanide consumption from 17kg/t to 8 kg/t.

Jan 1, 2014

By Jun Xiao, Yucai Zhou, Yanhong Dong, Daixiong Chen

"In this article research on the mineralogical characteristics and beneficiation process for a copper molybdenum deposits in Heilongjiang province of China has been carried out. Chemical analysis, X-ray diffraction(XRD) and Quantitative Evaluation of Minerals by SCANning electron microscopy (QEMSCAN) were conducted on samples. The bulk analysis results showed that: (1) Comprehensive recovery and separation of molybdenum & copper minerals was feasible by the flowsheet of first copper-molybdenum mixed flotation after grinding the ore samples to 61.88% -74µm and then separation flotation of copper and molybdenum after regrinding the Cu-Mo mixed concentrate to 83.26% -38 µm. The results highlight relationship between mineralogical characteristics of ore and comprehensive benefication method. (2) the combination of "" Sodium sulphide and sodium thioglycolate "" reagents are effective inhibitors of copper-molybdenum mixed concentrate, their selectivity performance is better than that of single reagent. Good flotation indexes were gained that might be directive experience to similar cases. KEYWORDS Mineralogical characteristics; molybdenite; chalcopyrite; flotation separation; inhibitor INTRODUCTION Copper and molybdenum metals are widely used in the field of metallurgy, aerospace, national defence, etc. Copper –molybdenum sulphide ore is an important source of copper and molybdenum metals. At present flotation is still the preferred methods to deal with the copper-molybdenum sulphide minerals (Yin, Z., Sun, W.et al. 2017; Ansari, A., & Pawlik, M. 2007; Hirajima, T., Miki, et al. 2017). Copper and molybdenum sulphide ores usually have the similarly good nature floatability(Miki, H., Matsuoka, et al. 2017), meanwhile most molybdenum sulphide ore has tiny grained-size(Castro, S., & Laskowski, J. S. 2015.) and closed relationship with other sulphide and gangue minerals which result in the coper and molybdenum separation problem. Base on the nature of the ore and flotation properties of the individual minerals contained in the ore, there are two methods are usually used to deal with the copper – molybdenum ore, including bulk molybdenum/copper flotation followed by separation of copper and molybdenum minerals, sequential molybdenum/ copper flotation(Liu, G. Y., Lu, et al. 2012). The latter method has the shortcoming of hard to activate the depressed copper minerals in the previous molybdenum flotation process, which may result in a large loss of the copper from concentrate, this disadvantage would avoid while adopting the former method. bulk flotation followed by separation process is to get the copper-molybdenum concentrate from raw ore first then separate flotation the molybdenum and copper minerals, benefit from the excellent floatability of both molybdenum and copper minerals ( Malhotra, D., Rowe, R. M., & Bhasin, A. K. 1986; Cao, Z., Yue, et al. 2017 ), it really easy to obtain the mixed concentrate. In order to get the high quality copper and molybdenum concentrate, the key technologies and difficulties are to realize the separation of the copper and molybdenum minerals which have the very similar natural floatability (Raghavan, S., & Hsu, L. L. 2015; Nakhaei, F. 2014)."

Jan 1, 2018

By A. Qaredaqi, M. Mohammadi

Wet High Intensity Magnetic Separators, for short, WHIMS are used for recovery of Iron ores with low magnetic susceptibility. A Jones patent WHIMS with "grooved plates" matrix is being used in Dry Tailing processing line in Hematite Recovery Plant at Golgohar mining & Industrial Co. for recovery of Hematite. In this kind of separators Matrices are used for increasing the Magnetic field intensity and providing high magnetic field gradient. The laboratory WHIMS in Golgohar Iron Ore and Steel research Institute is capable to provide a background magnetic field strength up to 0.85 Tesla and in presence of ‚expanded metal? matrix, magnetic field intensity could increase up to 0.9 Tesla. More than 50% of feed particles in this separator were finer than 36 micron and recovery of these particles needs more magnetic field intensity. Hence, ‚Grooved Plates? matrices with Js= 2 Tesla and 3.8 mm gap were constructed. Measurements indicated that magnetic field intensity around the matrix will increase to 1.25 Tesla. Graph of Magnetic field intensity around the matrix to background magnetic field intensity was plotted and a model with Rsquare= 0.9 was offered. In addition, magnetic field gradient and magnetic force were calculated. In WHIMS with feed top size of 150 micron, the main effective forces on separation process are the magnetic force and the hydrodynamic drag force. With assuming that the particles are smooth and spherical and the flow is laminar, Recovery of fine magnetic particles is problematic in this separator because of drag force. Considering these facts and mentioned model, finest particles that are recoverable in different magnetic field intensities were calculated. Computations illustrated that with magnetic field intensity more than 0.8 Tesla, particles as fine as 4 micron are theoretically separable but it should be noted that in practice a larger attractable particle size would be expected.

Jan 1, 2014

By S. Dwarapudi

Pelletizing of Indian chromite ores is more challenging due to their high refractory nature. High Cr/Fe ratio and high MgO content in these ores demand high firing temperatures and longer firing cycles but often result in low strength fired pellets. Aim of this study was to develop cold bonded chromite pellets for smelting in submerged arc furnace (SAF) from chromite fines using suitable binder that induce less gangue into the pellets but cures quickly. Different binders were studied through laboratory pelletizing experiments for their suitability for cold bonding the pellets. As result, a composite binder comprising organic and inorganic binding agents was found to be suitable and pellets made from the same were tested for their low and high temperature behavior. High temperature reduction studies revealed that pellets were resistant to disintegration up to 1200 °C.

Sep 1, 2012

By Z. H. Liu

We experimented with slurry which from one of coal preparation plant in Guizhou province and made researches on double hump gradation, one of critical factor of gradation technology, which can influence pulping character in the process of making coal water mixture (CWM). The purpose for it is to find the best particle gradation which can meet the requirements in concentration, viscosity, and stability for CWM. The final result is that the concentration, viscosity, stability of CWM can meet the requirement for industrial use while the rate of fine particle in the slurry is 70%~75% and the maximum concentration of 62%.

Jan 1, 2014

By Yimin Zhu, Dezhou Wei, Haijun Liang, Zhifu Zhou

It has been fairly well established by many experiments that Thiobacillus ferrooxidans (T. ferrooxidans), also named Acidithiobacillus ferrooxidans(Kelly and Wood, 2000),can depress the floatability of pyrite. However, the mechanisms governing the process have not been known completely. In the present investigation, wettability and electrokinetic studies were carried out to examine the surface chemical changes on pyrite before and after interaction with T. ferrooxidans or its secretions. Attachment of T. ferrooxidans to pyrite was observed using a scanning electron microscope. The results of experiments showed that, under certain conditions, T. ferrooxidans and its secretions would obviously change the surface electricity of pyrite and result in the iso-electric point of pyrite shifting notably. However, the surface wettability of pyrite hardly changed and its hydrophobicity increased little after interaction with T. ferrooxidans and its secretions. Based on the results of the present investigation it can be reasoned that the depression of floatability of pyrite is due to the reduction of surface free energy, rather than the increase of surface hydrophilicity of pyrite. The decrease of surface free energy weakens the attachment of collector to pyrite; during the process bacterial protein plays the most important role and the bacterial chemotaxis strengthens the effect.

Jan 1, 2003

By Kr. J. Dedelyanova

Selective flocculation of iron minerals could improve the economics of high intensity magnetic separation as concomitant process. When the minerals are finely disseminated is necessary a finer grinding to be applied which generates a lot of slimes. The HIMS is not enough efficient for particles below 20 microns ? territory where the selective flocculation is already well known industrial practice, so the combination of these two methods of beneficiation can bring a higher grade at high recovery to be achieved. The dynamics and selectivity of the precipitation process is studied in batch tests with flocculant starch and dispersants sodium silicate and sodium hexametaphosphate. The influence of preliminary conditioning with nitrogen acid at pH 2 before flocculation is also investigated. Flowsheet including these two methods is tested and the distribution of iron is shown.

Jan 1, 2014

By Vladimir G. Kochnev

"Autogenous and semi-autogenous grinding (AG and SAG) have been considered a step forward in comparison to conventional grinding circuits with several stages of crushing and using ball (and/or rod) grinding mills. However, existing AG and SAG technologies still can be improved and have an immense potential from the viewpoint of economic benefits.Experience gained by the Technics & Technologies of Disintegration Ltd. (TTD) in the research of grinding processes shows that comminution in AG and SAG mills can be performed in a more effective way. The company’s approach comprises the following elements:- Novel mill design- New liners and lifters- Novel discharge grid design- Technique of treating material of critical particle sizeA novel mill of the cantilever type capable to operate in the AG and SAG mode has been developed. The cantilevertype mill has a high diameter to length ratio, which dramatically increases the throughput rate, and is characterised by high reliability, fast installation and low capital and operating costs.Tests of the new heel-shaped liners, originally aimed at improving the intact condition of diamond, indicated that they play an important role in the grinding process. Tests performed by TTD jointly with ALROSA, MINTEK and Anglo-American Corporation, demonstrated that the heelshaped liners provided the increase in the throughput rate varying from 30 to 80 % and the decrease in power consumption in the range 30-55 % for grinding of kimberlite and platinum-containing ores.Investigation of the influence of the main grid parameters on the efficiency of grinding led TTD to a special design of a mill discharge grid, with a radial location of openings, the slot width varying from the periphery to the centre and the grid surface provided with “heels”. The design allows one to control the particle size distribution of the ground product without affecting the grid throughput rate."

Jan 1, 2003