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By Luo Chuansheng, Rao Jinshan, He Xiaojuan, Qiu Xianyang

The dissemination grain size of chalcopyrite is really fine and refractory grains of -10µm take up 25%. Dissemination relationships among chalcopyrite with pyrrhotite, pyrite, marcasite and gangue minerals are complex. Content of Fe-bearing sulphides and Fe-bearing silicates associated with chalcopyrite reaches to about 60%. It’s hard to liberate and separate chalcopyrite from pyrrhotite. The above four are the main mineral processing difficulties of a copper ore in China. Because of the similar floatability and poor separation effect between chalcopyrite and pyrrhotite, enhanced depressing and collecting method was adopted in Cu-S separation before 2009. Due to the different magnetism among chalcopyrite, pyrrhotite and Fe-bearing silicates, magnetic separation is creatively induced in Cu floatation circuit based on the in-depth study of process mineralogy. High efficiency and new Cu-S separation technology of "Rough concentrate regrinding-pyrrhotite rejecting from middling by magnetic separation" and a highly selective copper minerals collector YL-1 had been developed to solve the difficult problems of refractory Cu-S separation, which are heavy load of middling recirculation,difficulty in upgrading Cu concentrate, unstable locked cycle and low separation indexes. And grade of Cu concentrate has been increased by 3.33%, recovery of Cu and Ag has been increased by 19.32% and 10% respectively.

Jan 1, 2014

By B. A. Kutlin

29% of the total ore mined in the Russian Federation for copper production is finely disseminated copper-zinc-pyrite ores of the Ural Region. Physical and chemical characteristics of pyrite copper-zinc ores make for difficulties in obtaining high indices during processing. At present, the authors have elaborated the technology to improve the quality of copper concentrates up to 20.0% for the ones obtained during pyrite copper-zinc ore processing (based on the example of the ore mining and processing enterprise ?Uchalinsky GOK?, Russian Federation). There are examples of use of fair-sized pneumo-mechanical flotation machines by modernization of processing plants. Keywords: copper-zinc-pyrite ores, Ural region Russian, selective flotation, pneumo- mechanical flotation machines

Sep 1, 2012

By Xumeng Chen, Yongjun Peng, Dee Bradshaw

Regrinding rougher flotation concentrates has become a common practice when processing low grade and complex ores. It not only reduces the particle size and improves mineral liberation but also modifies particle surfaces and pulp chemistry due to the strong electrochemical reactions taking place during regrinding. Therefore, the floatability of minerals in the subsequent cleaner flotation is influenced by the regrinding conditions. This paper presents the effect of regrinding conditions on the mineral floatability from both industrial studies in the plant and fundamental studies in the laboratory. Different regrinding conditions were considered, including grinding media, the electrochemical properties of minerals, pulp chemistry (pH, Eh, DO), and breakage mechanisms in tumbling and stirred mills. Results indicate that the selection of regrinding conditions and mill types should not only depend on grinding energy efficiency and liberation but also depend on the surface properties and pulp chemistry produced for effective mineral flotation and separation at the cleaner stage.

Jan 1, 2014

By R. C. Miranda

Flotation is an operation widely used in mineral processing because of its aptitude to recover minerals of interest very efficiently. Flotation is often responsible for making possible the exploitation of mineral deposits of low concentration. In flotation various processes phenomena occur, some of which have still not been explained scientifically. Due to this fact, there are no models that can be widely applied in flotation control. Thus, in most cases, the control is done by experienced operators who are able to visually classify the types of foam into different categories and each one of them is associated with an operating actuation. In this situation, image analysis is configured as a solution that has already been employed in several ways. In this paper, a control strategy based on the colour of froth on a direct flotation of a nonferrous metal is presented. Moreover, the paper reveals the theoretical basis of the method, the critical points, difficulties and improvements that can be implemented. Data of grade were collected from the mineral of interest and RGB (red, green and blue) data of final concentrate of the froth. The mineral grade was collected and analysed during one month of operation and RGB was obtained using a camera. It was verified that the red colour showed the same trend of the grade curve in the concentrate. Thus, the use of this online data in optimising control was introduced. The laboratory grade is used to calibrate the colour set point. Therefore, it was possible to monitor in real time the trend of enrichment and depletion of a non-ferrous mineral in a flotation. It was possible to establish an online control strategy based on simple data acquisition. The result was an increase of 10% on production.

Sep 1, 2012

By S. P. Nagaeva, A. V. Kuptcova, O. Yu. Poperechnikova

"The present paper contains study results of gold morphology and grain size distribution in flotation concentrates produced from original ore samples from deposits of different genesis. Pre-concentration methods were used with selective dissolution of rock minerals and mineral heavy medium separation to obtain statistically valid data on gold grain size and morphology in concentration products. Special attention is given to study of flash flotation concentrates that is mainly used for coarse gold, underextracted in gravity circuit. Analysis of geometrical optics has allowed to establish that during flash flotation gold grains more than 150 µm can be extracted from 10 to 35%, and in some cases single gold grains above 300 µm. INTRODUCTION Distinctive features of gold that have a significant impact, and in some cases, decisive influence on its recovery into saleable products are mineral shape, grain size and morphology of metal particles, paragenetic associations of gold. Peculiar feature of coarse gold is its easy extraction during grinding from associated mineral components like quartz, sulphide and other and almost complete recovery into gravity concentrates (Lodeischikov V.V., 1997). Morphology of native gold is so diverse that different gold grains are better extracted using different methods of concentration. Compacted and rounded particles are easily processed using gravity concentration but low cyanidable and hard to process using flotation. On the contrary, lamellar, flake, dendrite and capillary aggregates of high specific surface are easily cyanidable and under definite conditions it has strong floatability (Lodeischikov V.V., 1997). Flotation of gold-containing sulphide minerals and free gold takes place simultaneously during flotation concentration. In case of low-sulphide ores, native gold takes the basic load, having the high density (15.6 to 18.3 g/cm3, for pure gold – 19.3 g/cm3) it has limited size and morphology for successful flotation. It is known that flake gold and fine-grained gold up to 0.1 mm are easily extracted (Lodeischikov V.V., 1997). Authors of the present paper performed a study of gold granulometry and morphology in flotation concentrates produced from gold-containing ores from two deposits of different types: gold-copper oxidized hematite ores and low-sulphide gold-quartz ores. Ores are different by both host rock composition, mineralogical and petrographic features, gold grade in mineral assemblage and morphology and size of precious metal. Common for both ore types is low-sulphide content and presence of free gold."

Jan 1, 2018

By A. V. Zimin

It is a well-known fact that usage of reverse cationic flotation in magnetite ores processing enables to improve the quality of magnetite concentrates. We designed an iron ore concentrate technology (with 70 -71 % of iron) including reverse cationic flotation in pneumo-mechanical flotators RIF (developed by RIVS Corporation, Russia) with good biodegradable etheramines as collectors for flotation of quartz. Practical application of high biodegradable flotation reagents decreases environmental impact risk of objects and enterprises of mining industrial complex. This work presents results of development of flotation technology for production of high quality ferruginous concentrates from magnetite ores of Russia and Ukraine deposits. Keywords: magnetite ores, reverse cationic flotation, ferruginous concentrates, pneumatic-mechanical flotation machines, environmental impact

Sep 1, 2012

By U. A. Peuker

"Steam Pressure Filtration (SPF) is a modified cake filtration process and is characterized by both washing and excellent de-watering of the filter cake. Compared to conventional gas differential pressure filtration, the filter cake is treated with saturated or superheated steam replacing pressurized air. Invented in the early last century, Steam Pressure Filtration has reached technical maturity in the 1990ies for inorganic particle systems, fine chemicals and coal. Especially the de-watering performance for fine particles systems below 50 µm make Steam Pressure Filtration an excellent option for the processing of fine tailings streams, to produce a stable material, which can be described by the methods of solids mechanics instead of paste rheology. The washing, which is due to the condensing steam, is able to reduce the ion load of the solid. This additional effect is able to generate a dry tailings material, which shows a reduced leaching potential of mobile ions, which originally derive from the process water. INTRODUCTION Steam Pressure Filtration is a process concept especially of hyperbaric filtration, which started its market entry in the 1990ies (Bott 1996, Bott 2002). Even though there have been many attempts to apply steam on filters before, the success story began with the combination of hyperbaric filtration and steam application and the technical solution to limit the steam treatment to a defined zone on the filter. This resulted from the scientific findings that steam mainly enhances the de-watering during the mechanical filtration (Gerl 1999). There are no or minor positive effects of steam application to a filtration process during cake filtration and after the steam breakthrough has occurred. Furthermore that time a sufficient control technology to regulate the steam consumption as well as suitable filter cloths became available. There is a growing need for de-watering technology in the mining industry, not only for the concentrate but also for the tailings streams. Several reasons argue against the established solution of damping the tails as suspension or paste into tailings ponds. There are ecological, political, societal and economic reasons, which question the tailings ponds more and more. Due to the increasing costs in the building and monitoring of tailings dams, which contain the tailing ponds, the concept of dry stocking using filtration technology comes into the game (Jansson 2016). Dry stocking converts the tailings stream form the suspension or paste state, into a material, which can be stockpiled. The latter typically is a moist flowable disperse particle system. The conversion involves a de-watering step, in which different types of filter equipment can be used, e.g. filter presses, membrane filter presses, automatic press filters or hyperbaric filters. For coarse products also vacuum filter can be applied. Due to its excellent de-watering performance and the easy scale-up properties Steam Pressure Filtration is further option for dry tailings stacking."

Jan 1, 2018

By A. I. Urvanzev, N. V. Shikhov

"In this paper, we present the study’s results of electrical separation processes on the basis of new separator designs, new technological solutions, and newly discovered effects. We considered the options of enrichment by magnet separation of magnetite and titanomagnetite ores, ores and products containing chromium and manganese, ores of non-ferrous and precious metals. During pneumo-electric separation of mixed iron ore of SMPC, 43.3% of the output of the concentrate with an iron content of 61.7% was obtained in one step, with extraction of 70.5%. The paper also presents the results of the finalization on the air-electric separator of the magnetic fraction when separating oxidized ores of MPPOO (mining and processing plant of oxidized ores) on the Jans polygrade magnetic separator. A concentrate was obtained with an iron content of 65.1% with the extraction of 95.0% and tails with an iron content of 13.0%. The possibility of obtaining low-silica concentrates from these ores with an iron content of 67.15 and a quartz of 2.88% is shown. Also, the results of tests on the enrichment of chromite ores on the firing-magnetic scheme with corona-electrostatic separation are considered. On the initial ore of the Don MPP (mining and processing plant), a concentrate with a content of 61.8% Cr2O3 was obtained with a quartz content of ~ 1.0%. The results of pneumo-electric separation with triboelectric charge of the separated particles are presented. The results of the tests indicate a principal possibility of enriching chromite ores without costly high-temperature roasting. Dry technology of enrichment of manganese ores with the use of electrical separation increases the quality of the oxidized concentrate to the first grade and raises the total extraction by 2 times. For the Chineya deposit of titanomagnetite ores with copper impurities, electroseparation operations were carried out on two samples with a Cu content of 1.93 and 3.75%, respectively. For a sample with a Cu content of 6.02%, a copper concentrate output of 24.42% was obtained with a Cu content of 23.82% and the extraction of 94.88%. The results of enrichment by electroseparation of gold-containing sulfide ores can have the practical importance. For ores of the Berezovskoye deposit, a pyritic concentrate containing 100 g / t of gold was obtained after two or three operations of IES (integrated energy systems)."

Jan 1, 2018

By l. Bokányi, T. Varga

"The recycling of waste car tyres is a very important environmental task. The waste tyres usually are re-used or recycled by thermal processes like pyrolysis, gasification or incineration. The main problem associated with these processes is the sulphur content of waste tyres originated from the vulcanisation process, which pollutes the environment and the valuable products (i.e. pyrolysis oil) as well. In our research the desulphurisation of waste, mechanically prepared tyre sample was systematically investigated by the biosolubilisation with Acidithiobacillus thiooxidans, strain Karitas. Parallel, the experiments with sterile 9K nutrient medium were also carried out. It was found that the vulcanisation sulphur can be solubilised due to both the bio- and the chemical leaching, although the bioleaching is more effective. The solubilised vulcanisation sulphur then forms precipitates. The precipitates are forming in the bulk solution, as well as on the surface of rubber particles. The origin of the precipitates was investigated using XRD and scanning microscopy with micro probe. The origin of the precipitates is different: while in the process of the vulcanisation sulphur solubilisation with 9K medium the jarosite (KFe3+3(SO4)2(OH)6) forms, the course of the biosolubilisation with Acidithiobacillus ferrooxidans Karitas is accompanied by the formation of the jarosite and the halotrichite (FeAl2(SO4)4 · 22H2O) as well. The formation of the latter is the biomineralisation. The mechanisms of the bio- and chemical solubilisations are rather different as it was found and experimentally proved by several tests, and depends on the retention time of the solubilisation. Special efforts were done to elaborate the proper separation of the precipitates from rubber particles. Combination of intense dynamic stirring and recycling flotation process to remove the precipitates was applied for this purpose. The surface properties of synthetic jarosite were revealed using zeta-potential measurements at different pH and in presence of collectors. The parameters of the flotation were chosen based on the revealed surface properties of the precipitates. Finally, the sulphur recovery of the recycled rubber was achieved as low as <0.5%, sulphur content of it 0.17%, 12-times lower than that of the waste tyre sample after mechanical preparation."

Jan 1, 2018

By G. Sedelnikova

This paper is aimed to elucidate the problem of copper losses in pyrometallurgical slag. Currently, flotation is used to recover copper from the slag and return the metal into the pyrometallurgical process, but the percentage of recovery frequently remains unacceptable. The process of copper leaching from the slag flotation tailings using biologically regenerated ferric sulfate is considered here as an approach to the issue. A sample of the slag flotation tailings containing 0.67% Cu and 4.99% Zn was supplied by the Urals Mining and Metallurgical Company (UGMK, Russia). The Cu and Zn speciation analysis of the sample demonstrated that Cu occurred as 58.1% oxide, 15.4% native Cu, and 18.1% secondary sulfides whereas chalcopyrite proportion was as low as 8.4%. Prevailing Zn species were refractory (58.9% Zn ferrite), and zinc oxide and silicate species made just 37.2% of the total metal content. The silicate generated silica gel that strongly hampered filtration. As demonstrated, Cu recovery is a possibility, which is apparently not the case with Zn. In this work, the stirred tank bioreactor acid leaching employing bacterial Fe3+ sulfate solutions was studied, with ferric sulfate being a product of Fe2+ biological oxidation and not the chemical reactant adding of Fe3+ sulfate. Acidithiobacillus, Sulfobacillus, and Leptospirillum bacilli were employed in Fe2+ biooxidation. Temperature, pH, Eh, S:L ratio, leaching time, and Fe3+ concentration in the source leachate as the process controls were considered. As demonstrated, the process employing biologically regenerated ferric sulfate proved to be more efficient than conventional chemical leaching. Under the optimum conditions, the proportion of Cu extracted into leachate during 2 hours was 79.1%, and that of Zn 27.2%. Precipitation of high-grade Cu sulfide served to extract the metals from the leachate, and Cu extraction was 99.7%. All in all, 23.2% Cu, 0.03% Zn, and 0.02% Fe was returned into the pyrometallurgical process. Keywords: slag flotation tailings, copper leaching

Sep 1, 2012

By D. J. Zhao

The reduction of ilmenite pellets was investigated at 950°C and 1000°C under a CO-N2 gas mixture with 10 L/min gas flow rate. All the reducing reactions were conducted in a furnace with a thermogravimetric analysis system. The reduction rate is higher at 1000°C than that at 950°C. At the early stage of the reactions, with the CO concentration increasing in the gas mixture, the reduction rate increased at 1000°C. In addition, at the early stage of the reactions, a rapid temperature increment and a rapid conversion of oxygen were observed on the curves of temperature versus time and conversion of oxygen versus time under different experimental conditions. The solid reaction products obtained in these experiments were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometers (EDS). Metallic Fe with small amount of Ti dissolved in it and oxides of Ti were found in the solid reaction products, but the formation of any nitride phases was not found under the prevailing conditions.

Jan 1, 2014

By E. N. Levchenko, K. V. Bulatov, G. I. Gazaleeva

"The article highlights the new procedure of choosing special methods of disintegration for very complicated rare ores. Especially, there is a complex approach to criteria of comparing different types of crashing machines. Criteria are as follows: degree of crashing, degree of grinding, degree of slime creation and the new creations criteria for selection. The procedure is tested on tantalium and zelestinium ore. A new methods was shown the preference impact crashing machine MD-7 for zelestinium ore. In product of crashing 0,050 mm size are 9.4 %, 0,005 mm size – 2.5 %.This is gut result, and show the best indexes of slime creation. The check of the proposed new methods was done when comparing the crushing of tantalium ores of the Otboynoe deposit in cone inertial and centrifugal impact crushers and roller press. A research was conducted different crashing machines under laboratory and semi-industrial conditions. Different operation modes of crushers were also checked. The comparison of the crushing selectivity criterion and degree of crashing showed that the centrifugal impact crusher (CC) and roller press (RP) has the lower indexes than the cone inertial crusher (CIC). Degrees of crashing for different crashing machines are:centrifugal impact crusher – 10.1;roller press – 10.8;cone inertial crusher – 14.2. The crusher CC the selection criterion is 0,632 units, RP – 0.730, where as for the crusher CIC – 0.848 units. The best crushing mode for the crusher CIC-300? is as follows: turning angle of debalance is 0°, peripheral speed of a cone rotation – 1420 r.p.m, specific energy consumption- 4.99 kW*t/t. Crusher CIC-300? is the best for tantalium ores of the Otboynoe deposit. The new methodic are verification.INTRODUCTION Rare metal concentration circuits are complex, energy-intensive, and costly. The reasons for this include the multimetal nature of the rare metal ores, their volatile material composition and low grade. That is why careful selection of ore preparation circuits is of great importance for minimizing the energy inputs and maximizing the liberation of the valuable minerals. Recent research (Khopunov, 2011, Gazaleeva, 2015) has demonstrated that the most efficient comminution processes available to the mineral processing industry are selective disintegration, crushing and grinding, allowing to liberate the mineral particles along the cleavage in the comminution process. These methods are indispensable for the processing of finely disseminated refractory ores prone to slime formation. Many rare metal ores found in Russia are of this type."

Jan 1, 2018

By A. An. Mushketov, A. Al. Mushketov, N. A. Sopina

"INTRIDUCTION At present, more and more metallized raw materials with a metallization degree of not less than 80% are used in the smelting of steel. The main quantity of this raw material is produced in furnaces of mine type. Advantages of this type of raw materials for metallurgical processing are low levels of harmful and slag-forming impurities and a high content of metallic iron. At the same time, the cost of smelting raw materials and obtaining high-quality steels are reduced. In addition to the undoubted merits of metallized raw materials, there are high requirements for the quality of iron concentrates, which are the starting material for metallization: the mass fraction of acidic oxides should not exceed 3%; The mass fraction of iron should not be less than 69%, mass fractions of harmful impurities (phosphorus, arsenic, sulfur, copper, etc.) should not exceed 0.02%. These requirements are dictated by the fact that the recovery of burned pellets is carried out by gas in a solid phase. In this case, the empty rock and harmful impurities from the metal are not separated and sent to the steelmaking unit, increasing the heat consumption for heating and worsening the quality of the steel. The combined production of high-quality concentrate and metallized raw materials requires a large capital outlay from the enterprise, which in the future can be compensated for by increased profit from the sale of more expensive marketable products. At present, in the territory of Russia and the CIS countries Lebedinsky mining-and-processing integrated works is the only enterprise that carries out the entire chain of operations for the production of metallized raw materials, starting with the production of high-quality magnetite concentrate with a mass fraction of iron of 69.5% and ending with the production of a metallized product in the form of hot briquetted gland. JSC «SSGPO» is the largest iron-processing enterprise in Kazakhstan, which processes about 40 million tons of ore per year and receives 16 million tons of concentrate per year with a mass fraction of iron 66.0-66.5%. The technological scheme existing at the concentrator of JSC ""SSGPO"" includes the crushing of the feed ore to the size of 20-0 mm; dry magnetic separation operation; three reduction stages to a fineness of 90-95% kl-0.071 mm; operation of desliming, wet magnetic separation and filtration of the concentrate. Dry magnetic separation of the feed ore makes it possible to remove from the process of 19.6% of the tailings with a mass fraction of the total iron 12.5%, of magnetite 2.2%. The first reduction stage is carried out in rod mills with the volume of 40 m3 to a size of -1.6 + 0.0 mm. The first stage of wet magnetic separation is carried out in counterflow magnetic separators PBM-P-150/200L. The magnetic product of the first stage of WMS is classified in hydrocyclones; sands enter the second reduction stage into central discharge ball mill 3600 × 5000. Runoff of mills enter on the second enrichment stage in counterflow magnetic separators PBM-P-150/200L. The magnetic product enters the classification of the second stage, forming a closed cycle. Mass fraction of the class -0.071 + 0 mm in classifications runoff of the second stage is 70-75%. The second stage classifications runoff is transported toWMS-III operation in semi-counter separators PBM-PP-120/300. The magnetic product of the third stage enters the classification of the third stage. Granular residue are transported to the reduction of the third stage into central discharge ball mill 3600 × 5000. The mill runoff enters the third stage of classification, forming a closed cycle. Classifications runoff of the third stage enters on deslimation. Deslimed product is sent for fine screening to the crasher «Derrick» 2SG48-60W-5STK with a cell size of 0.1 mm. Top size of crasher is sent to regrinding. Undersize with a mass fraction of the class -0.071 + 0 mm 90-95% is fed to the wet magnetic separation of WMS-"

Jan 1, 2018

By Victor Avdokhin, Ivan Kovlekov

"Studies of the process of concentration of gold-containing sands and technogenic resources show that the main reason of gold losses is misbalance between size of gold particles and degree of roughness of mineral bed. This results in free circulation of small gold particles in pores with following washing off the particles from the bed by turbulent flows.We elaborated design of magnetic sluice, intended for improving efficiency of recovering fine gold by optimizing magnetic field of a magnetic system on the base of forming catching coat from magnetic mineralsThe magnetic sluice includes trough-shaped body from magnetic-conducting material. On the bottom of the trough, magnets are placed, and opposite poles of the magnets are oriented outwards. Thickness of the bottom is determined to be sufficient for locking magnetic lines of force of the magnets on each other. The magnets of rectangular plate shape are placed on the rough bottom, covering the whole surface or with spare areas; the magnets are placed across the trough with alteration of rows with the same pole orientation.Catching coat is formed of natural magnetic and weak-magnetic placer minerals in field of magnetic system of the sluice. Magnetic minerals, placing along magnetic lines of force, form rough coat of fluffy structure. Size of the magnetic particles is chosen taking into account expected size of gold particles, which are to be fixed on the rough coat or between the magnetic particles. Changing coarseness of particles of mineral bed allows to regulate selectivity of recovering heavy minerals.Forming artificial fleece from magnetic minerals of initial sand, increasing capacity of the bed and relative hydraulic proportionality of mineral particles of the bed provide for the most effective recovery of fine gold."

Jan 1, 2003

By Luis Bergh, Iván Rojas, Juan Yianatos, Luis Vinnett

"At present, flotation rate characterization follows standard measurements to identify the overall flotation performance looking at the feed, tailings and concentrate in flotation cells or banks. This classical approach does not take into account the evolution of the true collection rate down the flotation banks explicitly. The potential for identifying the impact of the mineral characteristics (size and liberation) as well as the effect of different manipulated variables (reagents, froth depth, gas dispersion) on the true flotation process remains hindered. Top-of-froth (TOF) measurements, which consist of sampling the first layer on the froth surface, have been used to characterize the mineral collected by true flotation in rougher banks. The information provided by TOF samples allows evaluating the floatable mineral evolution (grade, particle size, liberation) down the bank. In this work, an indirect approach to estimate the flotation rate along rougher flotation banks is proposed. The new approach is based on the decreasing of collected mineral grades (on top of froth) and the feed characteristics. Flotation rates per liberation classes were used to reconstruct the TOF grades from the feed information. This approach requires a simple froth surface sampling, without constraints typically observed during mass balance surveys and uncertainties on the mineral recovery estimation. The proposed methodology was successfully applied at industrial scale using TOF measurements together with QEMSCAN information."

Jan 1, 2014

By A. V. Nguye, P. A. Harvey

Previous studies have reported that inorganic electrolytes can enhance floatability of coal. The research has shown that the enhancement, if any, is highly dependent on changes in solution pH, type of electrolyte, and electrolyte concentration. The reasons for this are still not clear. In this study the floatability of coal particles in mono and divalent salt solutions was investigated. The zeta potential and hydrophobicity of the coal was measured experimentally, and a modified Hallimond tube was used to determine the floatability of coal particles by single bubbles, where the collision efficiency was equal to unity. The experimental information was used in conjunction with the Hogg-Healy-Fuerstenau equation to quantify the electrical double layer interaction. It was found that for low electrolyte concentration (less than 0.1 M) solutions the flotation recovery of coal particles was less than that for distilled water, and decreased with increase in concentration. Conversely, at electrolyte concentrations above 0.1 M, flotation recovery increased with increasing concentration. Both of these results are consistent with previous observations, but are inconsistent with expectations when considering the possible influence of electrical double layer interaction. A possible mechanism, based on the existence of the pre-existing submicron-sized gas bubbles, known as bubstons (i.e. bubbles stabilized by ions), present in water in close proximity to the hydrophobic coal surfaces is discussed in line with the early observation of flotation improvements by microbubbles “nucleating” on hydrophobic surfaces. In particular, the dependence of the bubble-particle attachment efficiency on electrolyte concentrations supports hypothesis on the salt-dependent and ion-specific existence of bubstons. However, a theoretical explanation of the transition salt concentration (at about 0.1M) is deficient at present. The existence of these submicrobubbles in close proximity to hydrophobic surfaces is not trivial. They can (as can individual gas molecules or other solutes) mediate and extend the range and magnitude of the attraction between hydrophobic macroscopic surfaces. These bubbstons may explain the curious phenomena of the socalled long-ranged hydrophobic attraction measured with the Surface Force Apparatus and Atomic Force Microscopy, and the slippage at hydrophobic surfaces. Finally, the coalescence of bubbstons affects the rupture of liquid films at a very large thickness (over 100 nm), observed, but unexpected, by flotation chemists.

Jan 1, 2003

By K. Trybalski

Facing the optimization activities, which purpose is to minimize the copper processing costs, the main sources of their occurring were presented. In this purpose, the costs analysis was performed, divided to individual standings, for one of the polish copper beneficiation plants. It was proved, that the main component of the copper beneficiation costs is energy consumption, generated mainly in grinding and classification node, particularly by operating mills. The technological system ? grinding and classification node ? in KGHM Polska Miedz S.A., ZWR region Lubin was then selected to investigation. To evaluate the grinding and classification node, the energetic factors W were proposed, calculated on the basis of the energetic-technological data of process, given by node monitoring system. The correctness of the energetic factors selection to evaluate the work of this node and their practical application in industrial conditions was experimentally proved in other technological object. The selected technological object ? grinding and classification node ? was then mathematically modeled and optimized. The calculated energetic factors were the basis to build mathematical models, identifying industrial copper grinding and classification process. The models described correlation and character of dependency between factors and energetic-technical data of the process. These were regressive and neural networks models. On the basis of factors models, the optimization tasks were determined, which purpose was to select the optimal points of grinding and classification node work. Also, the estimated economical effect, possible to achieve after introduction of given monitoring values to grinding and classification node optimization system, was presented.

Jan 1, 2014

By L. A. Cisternas, R. I. Jeldres, C. Cruz, P. A. Robles

"Previous studies have shown that the floatability of chalcopyrite in seawater at highly alkaline conditions is significantly affected by the presence of clays. The reason is that the species of calcium and magnesium present in seawater under those conditions may act as a bridge between the surfaces of clay and chalcopyrite, generating massive aggregates that then depress. In this context, the objective of this work is to analyze the impact of pretreated seawater with low amount of calcium and magnesium ions on the recovery of a sulphide copper mineral with high kaolinite content as clay. The seawater pre-treatment is done by the addition of sodium hydroxide in a high carbon dioxide environment. The chemical reactions realized under these conditions lead to the formation and precipitation of calcium and magnesium species that are subsequently removed by vacuum filtration. The pre-treated seawater is then used in flotation tests at pH 11 for copper sulphide, where the mineral is synthetically prepared by mixtures of chalcopyrite, kaolinite, and quartz. When comparing the flotation results for different types of water, including seawater and pre-treated seawater, a significant effect is observed: as the seawater hardness decreases, which comprises the calcium and magnesium ions, the recovery of chalcopyrite is increased. However, the effect is markedly enhanced in the presence of kaolinite. Therefore, the results indicate that sodium hydroxide and carbon dioxide are able to remove different species of calcium and magnesium from seawater and could improve the chalcopyrite recovery with high kaolinite content. INTRODUCTIONIn many cases, mineral deposits are found in arid areas with little access to water resources. Water is a fundamental element to carry out the unit operations that achieved the separation of valuable minerals (especially in concentration operations). Seawater has acquired an interesting role in recent years (Cisternas and Moreno, 2014); in fact, it seems to be one of the few viable options to ensure the sustainability of the mining industry in arid zones. At present, there are numerous experiences of industries that use or have used this resource, either by submitting the seawater to a desalination treatment by reverse osmosis or by applying it directly, without desalting. The latter case may involve significant economic benefits (for example, by avoiding the investment of building a desalination plant) and in some cases some operational benefits. A positive aspect is that in general terms the foaming in the saline medium is much more efficient compared to fresh water (Quinn et al., 2014; Castro et al., 2010). Some reports show that the foaming doses required to achieve a certain quality of bubbles are remarkably reduced, reaching exceptional cases such as Xstrata's Raglan concentrator, where it did not even include foaming to carry out the operation. This fact is quite promising, considering that some researchers have stated that controlling the quality of bubbles and foam could float minerals through coarse particles. This would lead to multiple benefits, such as energy savings by avoiding excessive grinding and a lower presence of fine ore that causes major problems in water recovery operations by gravitation (such as thickening) and in tailings management. However, seawater also causes significant challenges in multiple operations (Jeldres et al., 2017, 2016; Castro et al., 2010), as for example in minerals with high clay content (Uribe et al., 2017). In fresh water, the presence of clays minerals in ores is already a major problem in the flotation stages since the operation becomes difficult to be controlled, and operators are commonly forced to increase the consumption of reagents because the collectors are deposited on the clays' surfaces reducing froth stability (Farrokhpay and Bradshaw, 2012). Sometimes the use of rheology-modifying reagents should also be incorporated since the pulps become more visc"

Jan 1, 2018

By B. Suresh

Iron ore in Bellary-Hospet region is friable in nature and generates a significant amount of micro-fines (-150 µm) during mechanized mining, handling and processing. Present beneficiation practice generally employs spiral classification followed by hydrocycloning to remove slimes (-15 µm). The iron ore fines, beneficiated at JSW Steel Ltd., Karnataka generates tailing having 48-52% iron content in the form of slimes, which accounts for 50 to 55% by weight with respect to classifier overflow. The loss of iron as slime is considerably high. In this context, laboratory studies were carried out with different combination of beneficiation techniques with an objective to develop an efficient flow sheet to achieve better product grade and recovery from classifier overflow. The results revealed that de-sliming process by hydrocycloning in combination with either magnetic separation or froth flotation leads to increased iron loss in tailing. Based on investigation it is observed that forward flotation is beneficial over the reverse flotation. The experimental approach of forward flotation on classifier overflow followed by magnetic separation on flotation tailing resulted in overall product grade of 62.9% Fetotal and 70.3% yield. The tailing contains 34.6% iron, which accounts for 29.7% by weight with respect to classifier overflow.

Sep 1, 2012

By S. P. Nagaeva, O. U. Poperechnikova, A. V. Kuptcova

"In case of free gold presence in ore, there is always problem of a choice between the gravity-flotation and gravity separation flowsheets. Study of morphology of gold being extracted by different methods allows to find the most efficient solution. One of the latest methods of gold concentration for wide range of grain size (-0.8+0 mm) is a flash flotation. The paper presents comparative testing results of flash and centrifugal separation.The goal of the studies was to determine process and flotation parameters of flash flotation. In case valued minerals are soft if compared to host rock, such minerals tend to concentrate into circulating load of grinding circuit. Thus, valued minerals can be overground, and in turn, will result in low extraction in flotation circuit. Integration of flash flotation operation into process flowsheet has been evaluated. Flash flotation operation can be successfully used not only for gold but also copper, lead, nickel and silver minerals.With low-sulphide ores being a case study under laboratory conditions, various flotation (impeller rotational speed, air flowrate) and process (pulp density, collector consumption, frother consumption, time of flotation) parameters were studied in view of its impact on gold flash flotation. Experiments were carried out under laboratory conditions using special pneumatic mechanical flotation machines.INTRODUCTIONGravity separation is used for extraction of coarse gold before cyanidation and before flotation of polymetallic ores to increase gold total recovery into gravity copper and lead concentrates.Benefit of the flash flotation is efficient recovery of coarse gold carrier particles (sulphides) thus preventing its regrinding and, as a result, low recovery. Furthermore, combination of flash and conventional flotation results in final tailings that do not require further cyanidation.Combined gravity-flotation flowsheets are designed for concentration of ores containing gold within thewide range of grain sizes (see Table 1)."

Jan 1, 2018