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By I. Kairyakov

The present paper is about the restoration of the molybdenum production in the floatation plant of Ellatzite-Med AD in Bulgaria. The process, based on a working design, includes the construction of a new floatation molybdenum section in the existing molybdenum department of the Floatation Plant using the so called Vemco inert-gas floatation machines, made especially for the molybdenum floatation. While in the ordinary floatation machines, block impellers create suspension of the air, sucked from the atmosphere with the slime particles of the concentrate, which creates conditions for oxidizing the reagent, Vemco inert-gas floatation machines are covered with hermetic lids and the air inside the chamber is used. The technology, suggested by Geotechkoper Ltd. for making the working project, employs special machines from Dor Olliver Aimco, suitable specifically for molybdenum floatation in order to reduce the oxidizing of the reagent sodium hydrosulphate. Also the transport of the chamber product is done in hermetic conditions as the molybdenum flotation is done in two floatation rows and refining operations 3 to 8 are placed in the second row. Thus in the basic molybdenum floatation together with the first and second refining operations, which are hermetically closed, an ambient condition with low content of oxygen is created, that is about 8% for oxygen and about 92% of nitrogen, in which the oxidizing process is extremely reduced. This in turn results in reducing the consumption of the reagent depressor ? sodium hydrosulphate. In that way there is an improvement of the economical indices of the molybdenum production.

Jan 1, 2014

By Paolo Bevilacqua, Paolo Antonini, Lorenzo De Lorenzi

"Ceramic production requires large quantities of K-feldspar, which is commonly sourced from granites, alkali-granites, and feldspathic sands. These rocks contain other minerals, such as quartz and plagioclase, which are undesirable for ceramic production. Due to the coarse mineral grains that constitute these rocks, a reasonable liberation is achieved at a relatively coarse particle size.The feasibility of feldspar-quartz separation using a dynamic dense medium separation system has been investigated as an alternative to flotation techniques. The use of a two stages cylindrical vessel (Tri-Flo) was preferred to a conical vessel, due to the improved separation efficiency.In a full-scale processing plant, a dense medium separation process can be used as a K-feldspar preconcentration step. This reduces the amount of material to be treated in the more expensive processes, such as finer comminution, flotation or magnetic separation.A comparison between commercial raw materials for the ceramic industry and the “rich in feldspar” products of the Tri-Flo process is reported, and the validity of the process is demonstrated."

Jan 1, 2003

By Mohammad Mainul Hoque, Linhan Ge, Ai Wang, Geoffrey Evans, Subhasish Mitra

"Dispersed phase interactions involving bubbles and particles in the turbulent environment play a significant role in the flotation process. The conventional collision models only account for the deterministic rather than the stochastic behavior of turbulenct flow. What the bubble-particle collisions would be like remains an open problem due to the complex nature of turbulent flow. To address this research question, the present study aims to quantify the bubble-particle collision efficiency incorporating turbulence using the computational method. Multiple solid particles were released to interact with a single stationary rigid bubble (non-deformable interface). Effect of particles Stokes number, turbulent intensity (TI) and integral length scale on the bubble-particle collision efficiency (Pc) was examined. Large Eddy Simulation method (LES) was used to compute the continuous phase. Fluctuating velocity required at the inlet boundary condition was derived from Gaussian energy spectrum to generate the upstream turbulence. Discrete Phase Model (DPM) is used to simulate particle trajectory. The characteristics of turbulent flow were analyzed through Energy spectrum and energy dissipation rate. The critical initial releasing radius of the annulus, where Pc equals zero, reaches up to 1.5(Rb+Rp) under high turbulent intensity (TI) 20.48% compared to 0.23(Rb+Rp) calculated from the traditional Pc model. Pc decreases as the distance of initial releasing annulus between bubble centre increases. Pc increases as particle Stokes number increase up to 0.66. The collision efficiency for particles of St less than 0.38 is higher under TI 11.78% compared to TI 4%.INTRODUCTION To increase mineral recovery, interactions between bubbles and particles are essential. All flotation devices achieve it through introducing some level of turbulence into the system by increasing specific energy dissipation rate. Figure 1 shows three different flotation equipment, traditional floatation cell, Concorde cell and cyclonic-static micro-bubble flotation column (FCSMC), with different turbulence generation mechanisms – impeller, down-flow liquid jet and pump recirculation, respectively."

Jan 1, 2018

By P. K. Fedotov

Centrifugal separation opens its new application fields in the Mining Industry. The up-to-date equipment for ultra-fine ore and concentrates grinding allows an efficient use of centrifugal concentration for micronic gold grains recovery. Moreover, advanced centrifugal concentrators are presented on the market: concentrators with continuous concentrate discharge designed both for ore and non-metallic minerals concentration process. The conducted tests proved the centrifugal concentration to be efficient process for gold recovery from finely ground concentrates and ores (less than 20 µm). Knelson concentrator application for such a fine material in different process circuits makes possible to raise the total gold recovery level of plants. In the circuits of coal plants and in course of coal slimes treatment the centrifugal concentration may be used before flotation in order to improve process performances. A centrifugal concentrator KC-CVD with continuous concentrate discharge working on 0.3 (0.5)mm fraction before flotation is

Jan 1, 2014

By Prasad Kopparthi, Narasimha Mangadoddy, Balraju Vadlakonda, A. K. Mukhurjee

"Column flotation (CF) is widely using equipment in mineral processing since many years. ERT technique facilitates non-invasive and nonintrusive visualization of different parameters in a column flotation. The hydrodynamic investigation of two-phase and three-phase are studied using electrical resistance tomography (ERT) coupled with pressure transducers in laboratory column flotation. Bubble size distribution, bubble rise velocity and gas and solids hold-up hydrodynamic parameters are extensively used for column flotation design and performance evaluation. The effect of superficial gas velocity, feed flow rate and slurry height in the column on mean gas holdup and its radial distribution has been analyzed for both two-phase and three phase flows. Influence of solid particles on gas hold-up and its complete elucidation of dispersion in the column are assessed. Experimental results show ERT coupled with PT is suitable as an online monitoring tool to provide useful information on the hydrodynamic parameters of the column flotation. The tomography images, which were generated using a modified sensitivity back projection algorithm, were employed to explore the parameter study in two phase flow in column flotation.Furthermore, the results also indicate that ERT is a very powerful tool for diagnosing the `inside' flow behaviour of gas-liquid two-phase and gas–liquid–solid three-phase flow in columns operating for a wide range of flow regimes.INTRODUCTIONColumn flotation is being widely used in mineral processing industries in last few decades. There has been a lot of attention in understanding the various mechanisms that take place during operation. Due to many reasons column flotation has been found to yield better performance than conventional flotation cells, particularly with fine particles (Honaker and Mohanty, 1996). Due to complex flow behavior in nature, the performance of column flotation influenced by on flow characteristics of the process, (Jena et al., 2008). Previously basic research is carried out to evaluate the effect of the hydrodynamic parameters on the performance of column flotation (Finch and Dobby, 1991)."

Jan 1, 2018

By E. Lee

With the growing environmental concern, as well as the increasing concern for sustainability of natural resources, the need of improving the performance and efficiency of today?s crushers is be-coming increasingly important. However, the development of existing crushers requires an extended basic knowledge about the crushing process itself. The aim of the present study is therefore to find the theoretically optimal way of crushing compressively under given circumstances. In the present paper, optimizations have been performed with the purposes of maximizing product yield and minimizing energy consumption. Performed on an ideal crushing stage free from physical limitations, the optimization results have been obtained in terms of number of compressions and their corresponding compression ratios. Complementing earlier results on interparticle breakage (Hulthén et al., 2006), presented here are thus the results from corresponding optimizations with single particle breakage and interparticle breakage. It is concluded that modern crushers are not working optimally in any of the studied aspects for gneiss. In fact, optimizations indicate that a lowering of the compression ratio, as well as a shortening of the crushing sequence, are theoretically favourable. The outcome of this study is therefore highly promising as to giving new ideas and suggestions of improvements in existing crushers, and can even result in redesign of compression crushers.

Jan 1, 2014

By B. McFadzean

Thiol collector mixtures are commonly used in the flotation of base metal sulfides and platinum-bearing ores. There are synergistic benefits claimed for these collector mixtures, with mixtures lowering total dosage requirements, improving coarse particle recovery and the rate of flotation. Some of the secondary collectors are known to have frothing effects. Therefore, a previous study aimed to decouple froth and pulp effects and considered only the bubble-particle attachments in the pulp. This was achieved through microflotation experiments, where various ratios of the ethyl and isobutyl chain lengths of xanthates, dithiocarbamates and dithiophosphates were used as collectors. Results from these experiments showed a marked increase in galena recovery using mixtures of xanthate with either dithiophosphate or dithiocarbamate. In the current study, the froth phase was introduced in the form of batch flotation studies to determine whether benefits noted during microflotation experiments would be carried through to a more realistic froth flotation scenario. The findings show that there was no significant difference in the flotation recovery between the best single collectors and mixtures of these collectors. In addition, single collectors that behaved poorly in microflotation experiments showed good flotation performance in the batch flotation experiments. The differences between the microflotation results and the batch flotation results are attributed to differences in particle froth stabilizing properties and/or differences in energy input between the microflotation and batch flotation cells. In addition, galena and pyrite showed marked differences in frothing effects and in their preferences for collector type. Keywords: froth flotation, collector mixtures, sulphide minerals

Sep 1, 2012

By G. S. Zeng

The mechanism of cobalt removal from zinc sulfate solution with zinc dust is still not understood well. The experiments in this paper were carried out by zinc dust from zinc sulfate solution with high cobalt to study the mechanism of cobalt removal. Residues after the cementation process from zinc sulfate solution were analyzed by SEM and Electron probe micro-analysis (EPMA) to investigate the morphology of products. Different temperature will cause different structure of particles. With the increasement of temperature, cobalt removal can be improved considerably. The mechanism of cobalt removal by zinc dust is thought as follows: firstly, the cobalt ion forms Co-Zn alloy with zinc particles, and the reaction reaches equilibrium quickly; secondly, the Co-Zn alloy continues reacting to Co with Co2+, which is the control procedure of the whole reaction.

Jan 1, 2014

By R. L. Pascual, W. J. Whiten

"The froth flotation process is not well understood. Both flotation models, and the parameters used to describe the stream flows are not well defined. They in fact vary considerably in different applications. This creates difficulties is designing a simulation program suitable for use by plant personnel, consultants, and researchers. In addition to simulation, an effective simulation program can be expected to provide a range of other services.This paper shows how a process circuit simulator can be designed with sufficient flexibility to satisfy these needs, and discusses some of the additional services."

Jan 1, 2003

By V. E. Vigdergauz

Possibilities of the analysis of potential energy of bubble-particle interaction on the basis of extended DLVO theory are discussed. Interaction energies of mineral silica, coal and pyrite particles with contact angles from 20 to 100 degrees and air bubbles in neutral and alkaline solutions are analyzed. It is shown that for hydrophilic silica, the formation of particle-bubble complexes (either in the area of primary or secondary potential minima) is impossible due to the high potential barriers (from 6000 to 140000 kT)and low values of the attraction force. There is shown that for coal and pyrite particles the energy of interaction vs. particle-bubble distance strongly depends on pH value. Improvement of floatability of minerals by the hydrophobization of their surface by collectors leads to the eliminating of potential barriers and the formation of the stable complexes of minerals and air bubbles in the area of primary potential minimum. In addition, due to hydrophobization of coal and pyrite changing pH has practically no influence on the energy of interaction. There are discussed results of the numerical calculations of normalized interaction forces in particle-bubble systems on the nanometer distances for pyrite, sphalerite, and chalcopyrite at contact angles up to 85° in comparison with the experimental data. The values of adhesion force for hydrophobized particles of coal and pyrite to air bubbles are about 10-5 N, that indicates stability of the formed flotation complexes. Examples of using the long-range and high-energy effect of hydrophobic interactions for improving minerals floatability are discussed. There are illustrated minerals wettability changes induced by the adsorption of thiol collector and hydrophobic polymer. Possibilities of flocculation and flotation of mineral slimes due the polymer-collector hydrophobic interactions are shown. Keywords: bubble-particle interaction, contact angle, extended DLVO theory, floatability

Sep 1, 2012

By A. Prokopiev

The biological stage of reclamation is the third final stage in remediation the damaged mining terrains, which is carried out following the completion of the mining technical stage. The biological stage of reclamation is carried out through restoration of the vegetation layer. The biological reclamation includes all activities related to the introduction into the terrain of vegetation, microorganisms, insects, and animals, with the acceleration of the succession and creating conditions for a sustainable ecosystem close to the natural one. It comprises of all anti erosion and other activities such as the preparation of the land for growing agricultural crops, sowing grass seeds, planting seedlings, amelioration of the soil and further care for the vegetation until its final place on the land. Mineral and organic-mineral ameliorants for biological reclamation were studied. The basic mineral ameliorant is Bulgarian natural zeolites. The zeolitic-rich tuff samples provided from Golobradovo deposit was characterized by their chemical and mineralogical composition and ion exchange properties and X ray analysis. The average content of clinoptilolite was found to be more than 80%. The materials had ion exchange capacity (NH4+) varying from 100 to 110 meq/100g. Chemical modifications of natural clinoptilolites were made in order to form active phases of nitrogen, phosphorus, potassium, and microelements. Slow-acting mineral ameliorant was developed. Organic-zeolite substrate for biological reclamation was developed. This new product is a mechanical mixture of organo-matter and modified zeolites. Agro-chemical parameters of new ameliorants were determined. The substrates including studied overburden dump soil and mineral or organo-mineral ameliorants are produced. The grass growth test was performed. Keywords: biological reclamation, ameliorants, damaged mining terrains

Sep 1, 2012

By J. P. Dai

The Fankou Mine in Guangdong province, China, processes a polymetallic ore containing averagely 4.2% Pb, 8.5% Zn, and 90 g/t Ag. The main metal minerals including sphalerite, galena and pyrite are very finely disseminated and unevenly occurred in the ore, making it difficult to liberate them from each other. This paper presents the processing technology of the Fankou plant and the characteristic features of the novel technology applied.

Jan 1, 2014

By Bertil I. Pålsson

The most common REE containing mineral that is worked today is bastnäsite. It means that mineral processes are adapted to it and that the metallurgical separation techniques for winning of individual REE are adapted to bastnäsite concentrates. For all other deposit types, suitable mineral processing methods and separation technologies need to be adapted and/or developed. Preliminary mineralogical analyses indicate that slightly less than half of the REE in the tailings dumps at LKAB/Kiruna are associated to apatite. The rest is in the minerals monazite (maybe associated to apatite) and allanite. At least allanite is probably not floatable with reagents commonly used for apatite. Mass and element distributions for the tailings sand reveal that very little apatite is present above 300 µm, and that approx. 30 % is below 20 µm. REE does not follow P2O5 completely and are also present in coarser fractions. Flotation results show that the best condition for both apatite and REE winning is pH 9, high collector addition and low dosage of water glass. Under these conditions, the lab-scale flotation gives an apatite concentrate with at least 30 % P2O5 at 70 % recovery. REE follows apatite in the cleaner steps but only partly. Its recovery is approx. half compared with apatite. The reason for the low REE recovery is likely to be that REE to a large extent is trapped in non-winnable minerals, especially allanite. The REE grades in the concentrate are expected to be in the range 3000 ? 4500 g/ton. Keywords: flotation, REE, apatite, monazite, allanite

Sep 1, 2012

By M. F. He

The depression of pyrite in marmatite flotation by a new depressant Sodium Glycerine-xanthate (SGX) has been investigated through microflotation, zeta potential, and adsorption measurements in systems open to the atmosphere. The flotation tests of single mineral show that in the presence of SGX, marmatite can be activated by Cu2+ and shows good flotability, while pyrite can?t be activated and therefore shows poor flotability, as a result these two minerals can be separated using butyl xanthate as the collector. The depression mechanism of SGX on sulfide minerals is discussed based on Zeta potential and adsorption isotherm. Zeta potential experiments demonstrate that at the presence of Cu2+, SGX can strongly adsorb on the surface of pyrite, while it can?t adsorb on the surface of marmatite, thus the results are in accordance with those of flotation experiments; the results of adsorption isotherms show that the adsorption density of SGX on pyrite is greater.

Jan 1, 2014

By B. Q. Xiao

The nitrate content is an important factor for environmental water samples and flour. In a 0.35 mol/L H2SO4-2NO solution, has a strong catalyzing function on the decolourization of Gallocya-nine (GC) oxidated by NaBrO3. Based on this, a novel method was developed to measure the NO and -3NO concentrations in water and flour. The flow injection technology was introduced into the analysis system. A single-valve dual- cingulums to inject which the Copperized-Cadmium slice and the reduction zone are isolated. The optimum solution for this method contains 1.48×10-4 mol/L GC, 0.06 mol /L NaBrO3 and 0.2 mol /L of NH4-2NOCl. Two empirical equations were proposed to calculate the and -3NO concentrations based on the measured signals. It can be used to measure -2NO of from 0.001 mg / L to 2.0 mg/L and -3NO of from 0.002 mg / L to 2.5 mg/L. The measurement frequency can be up to 20 samples / h. The relative standard deviation for eleven samples is less than 5%.

Jan 1, 2014

By Z. Y. Ma, M. D. Liu, Z. Z. Liu, J. K. Zhou

"An optimization method of microwave assisted leaching of copper anode slime was proposed based on Taguchi method. The results showed that the solid-liquid ratio was the most important factor affecting SNR(signal noise ratio) of the copper, tellurium and selenium leaching efficiencies, and its contributions to the copper, tellurium and selenium leaching efficiencies were 58.34%, 55.54% and 60.74%, respectively. Solid-liquid ratio was a significant factor to SNR(copper, tellurium and selenium). Reaction period was a less significant factor to SNR(copper and tellurium) and concentration of sulphuric acid was a less significant factor to SNR(selenium) while microwave power was an non-significant factor, its contributions to the copper, tellurium and selenium efficiencies were 3.22%, 11.73% and 12.73%, respectively. The optimized parameters of the microwave assisted leaching of copper were as follow: microwave power of 500 W, reaction period of 10 min, solid-liquid ratio of 0.10 g·mL-1 and H2SO4 concentration of 1.0 mol·L-1. The optimized parameters of the microwave assisted leaching of tellurium and selenium were as follow: microwave power of 800 W, reaction period of 15 min, solid-liquid ratio of 0.10 g·mL-1 and H2SO4 concentration of 1.0 mol·L-1. The validation experiments under the optimized conditions has been carried out, the copper, tellurium and selenium leaching efficiencies were 98.66%, 84.32% and 64.54%, respectively. INTRODUCTION As important valuable by-products, copper anode slimes are collected from the bottom of the electrolytic bath in the electrolytic copper refining process(Kilic, 2013). The value of the anode slime is determined by the content of rare metals and precious metals(Liu, 2014). Generally, pretreatment of copper anode slime is the first stage of the whole process. The aim of the pretreatment process is to remove Cu, Te and Se etc and enrich the valuable metals. The methods of pretreatment process can be differentiated into: pyrometallurgical processing and hydrometallurgical processing(Amer, 2003). The hydrometallurgical processes are more promising compared to pyrometallurgical processes in terms of cost effectiveness, low energy consumption and environmental concerns(Ranjbar, 2014). However, the disadvantages of the hydrometallurgy process are evident, such as lengthy processing times and low efficiency. Therefore, it is necessary to develop a highly efficient and environmentally friendly pretreatment method."

Jan 1, 2018

By N. Vorob?ev-Desyatovskii

The process of gold(I) adsorption on activated carbon (AC) from aqueous Na[Au(CN)2] and the state of the adsorbed gold cyanide complex on the adsorbent surface was investigated by photometry, XPS, XANES methods. By DFT method, quantum-chemical calculations were performed of the gold cyanide species on activated carbon surface. It was established that the binding of gold(I) with the surface of carbon involved several simultaneous processes governing the selective adsorption of gold(I) from the cyanide solutions.

Sep 1, 2012

By Ye Junjian

The feed ore is the concentrate of low intensity magnetic separation of pyrite tailings, containing TFe47.47%, S19.41% and SiOpyrrhotite. The exploratory tests showed that using a process of flotation followed by magnetic separation could respectively obtain a sulphur concentrate of S 31.08% with a recovery of 82.89%, and an iron concentrate of TFe 59.97% and S 9.52%with a recovery of 30.93%. The reason of iron concentrates with high sulphur grade was that the sulphur grade of flotation tailings was 7.03%. So enhanced flotation for pyrrhotite was investigated in this research. Results show that when the natural pH of ore pulp varied from 5.5 to 6.0, a reagent combination of FS, LH, and BJ displayed the optimum flotation performance for pyrrhotite. After comparisons made on different flotation processing, the previous flotation flow of ?one roughing, one cleaning, one scavenging system and middling reprocessing?, was found, among others, to have the best flotation effect, as the grade and recovery of sulphur concentrate were 31.08% and 82.89%, respectively, and sulphur content of the flotation tailings was 7.03%. The above results indicated it was difficult to raise further the effect of flotation desulphurization. The authors therefore suggested that oxidizing roast should be adopted following the magnetic process for the purpose of further desulphurization. Besides, flue gas containing SO2 8.25%. And the valuable minerals are magnetite and 2 generated from roasting could be reused for sulphuric acid production. Keywords: pyrrhotite, enhanced flotation, desulphurization

Sep 1, 2012

By S. V. Petrov

In recent years, heap leaching of gold is becoming wide spread due to low capital and operational costs that allows economically feasible processing of low-grade and cut-off grade ores. Currently, over 30 heap leach projects are operated in Russia. Some of the deposits treated by heap leach methods are almost depleted. Therefore, they will soon require spent heaps detoxification and reclamation. Traditionally, spent heaps are detoxified by chemical treatment. This process is characterized by relatively high kinetics and requires expensive reagents and additional equipment. The main disadvantage of this process is secondary contamination of the solutions by products of detoxification reactions and impurities contained in reagents. If there is enough time, spent heaps can be detoxified by natural degradation. The advantages of the proposed method are low operational costs due to use of existing heap leaching facilities and eliminating the need for chemicals for spent heaps detoxification. Residual concentrations of cyanides and thyocyanates in liquid phase (wet ore) of spent gold ore heaps after detoxification were 0.2~0.3 mg/L. Heavy metals were almost completely removed. The method was successfully used for detoxification of spent heaps at two gold mines.

Jan 1, 2014

By P. Raghavan1

Reverse froth flotation experiments were carried out in the laboratory using two different types of kaolins for the separation and removal of coloring titanoferrous impurities from cryo-filtered clay after subjecting to high shear pre-treatment. This high shear pre-treatment consists of high shear agitation of a high solids clay slurry with the dispersant (high shear dispersion, HSD) followed by high shear agitation with the collector (high shear conditioning, HSC). After this pretreatment, the slurry is diluted and reverse flotation is carried out. One sample is from, Gujarat, India (Mamuara clay, ?MC?) while the 2nd sample is from Amberg, Germany (AKW clay, ?AC?). While MC consisted of 89% particles below 2µm and analyzed 1.06% of TiO2 and 0.29% Fe2O3 and measured a brightness of 83.4 %ISO, the corresponding values for AC are 67% below 2µm, 0.3% of TiO2? 0.49% Fe2O3 and 83.4 %ISO. The flotation performance is found to be greatly influenced by the conditions of high shear treatment. Important variables are HSD intensity (rpm), HSD time, HSC intensity (rpm), HSC time, HSD/HSC time ratio, ?HSD+HSC? total time etc. Higher shear intensities favor both the impurity liberation and collection. For both clays, it could be shown that impurity removal increases as total pretreatment time (?HSD +HSC? total time) increases up to a certain limit. For MC, the HSD time was only half or less than that of HSC time, while for AC, HSD time is at least twice (or more) than HSC time which is just an opposite manifestation. This is believed to be due to the striking differences between these two clays. Most importantly, the shear frequency is found more influential than the shear rate for the overall flotation performance for both clays. Interestingly, at high shear frequencies, i.e., when a stirrer with more number of teeth on the rotor is used, the ?HSD+HSC? total time is greatly reduced. Again, increased shear frequency helps to reduce flotation time and significantly improves flotation performance. At optimum conditions, product titania reduced to 0.35% for MC whereas the same reduced to 0.13% for AC. The product of flotation of MC measured 85%ISO brightness while that of AC measured84.6%ISO thus enhancing the value of the final product. It could also be established that the high shear pre-treatment shows better flotation performance than that due to collector dosage. Keywords: high shear dispersion, high shear conditioning, titanoferrous impurities, shear rate, shear frequency, brightness, clay recovery, Mamuara clay, AKW clay

Sep 1, 2012