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By Scott C. Brown, Ivan U. Vakarelski

The particles commonly encountered in mineral benefication schemes have irregularites that are expressed at many different length scales. In part, this originates from preceding processes (e.g. makedown, comminution, handling and storage), which are known to chemically and physically modify the bulk particle and its surface. Interparticle tribology, dissolution and reprecipitation events along with large-scale mechanical stresses are just a handful of the interactions encountered during processing of particles prior to separation. It is feasible to imagine that each one of these events may impose a fingerprint of characteristic nanoscale, microscale, and macroscale morphological changes that can modify the overall interaction of these particles within a system. Suprisingly there are just a few works on how these resulting features can alter the performance of benefication schemes, and especially flotation.

Jan 1, 2003

By G. C. He

Effects of irregularity, rough surface and aggregation of fine particles on ultrasonic attenuation are significant. The effects should be considered while predicting particle size by ultrasonic attenuation technology. The scanning electron microscope micrographs analysis also shows that particles surface is rough and irregularity. Any slurries has its fractal structure and its special fractal scale and dimension, so, effects of irregularity, rough surface and aggregation of fine particles can be de-scribed by fractal model. The discrepancies between predictions of ultrasonic attenuation based on the assumption of smooth spherical particles and data obtained from slurries of irregular particles indicated that there were different fractal structures. The ultrasonic attenuation model was modified by fractal dimensions. The result of experimental data and analogue calculation indicated that pre-dictions of the fractal modification of ultrasonic attenuation model show good agreement with experimental data. On the other hand, from the values of fractal obtained by inversely calculation, the degree of effects of irregularity, rough surface and aggregation of particles can be estimated. The positive value of fractal dimension indicates that the aggregation has the dominant effect on ultra-sonic attenuation, otherwise, the irregularity and rough surface has the dominant effect.

Jan 1, 2014

By Y. P. Huang

Experiment results and operation practice on reutilizing old tailings dumped at SCIM (Shang-chang Iron Mine) of KISCO (Kunming Iron and Steel Corp.) are presented. In a production period over 30 years SCIM dumped about 8 million tons of iron ore tailings. For improving resources utilization instead of wasting, experiments on processing for reutilization of the old tailings are con-ducted. These tailings are fine size fractions of weathered iluvial ores rejected out by classification- des-liming in ore washing and dressing processes, containing TFe 21%~22% in hematite mainly and limonite occasionally. Their particle size distribution, in average, is of 72.26% minus 0.037mm and 30.88% minus 0.005mm. Existence of plenty of micro-fine particles makes the tailings refractory to process, resulting in poor metallurgy. The whole sample of the old tailings without size-classification is fed into experimental process. Slon-100 type high grads WHIMS (wet high intensity magnetic separator) with cyc-pulsing is adopted, which magnetism-focusing rod?s diameter is changed from 3mm into 2mm. Operational conditions of optimizing rougher separation tests are strengthened. An iron concentrate assaying 52.21% Fe at quantity rate of 18.39% and iron recovery of 44.40% is obtained. Operational practice shows that metallurgy and economy of the old tailings treatment are close to what achieved at experiments. It is estimated, therefore, that some 1.4 million tons of this iron concentrate may be recovered from the old tailings. This means that KISCO has moved its key one-step in re-mining and reutilizing the secondary resources, which would be a good demonstration in this industry. This is also of social and economic significance in response to China government?s request on reducing consumption of resources and establishing society with economy for achieving sustainable development.

Jan 1, 2014

By Brian Lindner, Lidia Auret, Niel Knoblauch

In this paper, a fault detection and identification framework based on feature extraction and topology extraction methods is proposed, and evaluated on a simulated base metals refinery high pressure leaching process. Feature extraction methods included linear and kernel principal component analysis, while process topology information was extracted with linear cross-correlation, partial cross-correlation and transfer entropy. Connectivity maps were constructed to identify possible fault propagation paths to aid root cause analysis. The results indicate that process topology can enhance the fault identification capability of data-based process monitoring methods. The study of the considered base metals refinery pressure leaching process is ongoing, with future work including the creation of a fault library which would lead to further critical evaluation of the proposed fault detection and identification framework.

Jan 1, 2014

By Ray Everson, Henry Kasaini

"Adsorption of Pd (II) anions on the surface of activated carbon (Norit 0.8) occurred at high proton concentration (0.01 – 2.5M, HCl) in the feed and averaged 27 mg/g. The adsorption process was interpreted in terms of surface ionisation and adsorption model. Enthalpy of adsorption averaged 0.4 kJ/mole indicative of an instantaneous physical adsorption process. We found that the Toth isotherm fit the adsorption data fairly accurately. A combination of the Langmuir and Freundlich equations yields an effective three-parameter Toth equation (1) which is frequently used to describe adsorption on heterogeneous surfaces.Figure 1 shows the comparison between experimental results and the model isotherms. We found that Langmuir isotherms underestimated the adsorption capacity on the porous surface while the Freundlich isotherm overestimated adsorption. Furthermore, the surface coverage at equilibrium was well described by both the Langmuir and Toth isotherms. But, Freundlich isotherm predicted a surface fraction coverage that was higher than unit. Based on better prediction of surface coverage and a reasonable fit to adsorption data, we concluded that the Toth isotherm best described the adsorption data of palladium. The adsorption process was limited by mass transfer resistance through the external film. We estimated the rate constant from equation (2), where e, ?b, and rp are porosity, fluid density and particle radius, respectively"

Jan 1, 2003

By S. M. Javad Koleini

The aim of this research is to extract zinc from complex lead and zinc ore containing carbo- silicate lead and zinc minerals using sulphuric acid. Samples, taken from Dareh Zanjireh mine located in central of Iran, were subjected to leaching tests after calcination process. Experiments were planed according to the Taguchi statistical method. The calcinated samples contain 13.98% zinc and the constituting minerals being dolomite and zincate. Various parameters such as speed of mixing, temperature, time, solid to liquid ratio and pH were studied. A solid to liquid ratio of 1:6 gr/mL at 60°C and 800 rpm speed of mixing for 30 minutes resulted in a product with 85.96% zinc recoveries.

Jan 1, 2014

By Z. B. Pan

The innovative point of this new technology can be described that under normal pressure and 70°C, using a new combined activating and oxidizing agent, the minerals bearing arsenic and organic carbon are oxidized effectively. This technology can be applied in commercial scale. The high carbon and arsenic bearing gold ore is taken from Gansu, where hundreds of tons gold deposit. The ore has 0.51% of arsenic and 1.75% of carbon (1.07% of organic carbon). The gold occurs mainly in native with particle size 0.02~0.6 mm and a few are enwrapped by pyrite and arsenopyrite. The traditional cyanide leaching process gains a very low gold leaching rate with only 5%. Through systemic experimental study, the technological flowsheet of flotation process for concentrating gold, then pre-treating the gold concentrate followed by cyanide leaching the gold concentrate are used. With 4.92 g/t gold of head sample, the gold concentrate with 46.52g/t gold grade and 96.53% gold recovery is gained by flotation process. Followed by pre-treatment for 6 hours, the gold concentrate is leached with cyanide after filtration and washing. The total gold leaching rate is up to 95.44%.

Jan 1, 2014

By Máximo Pérez, Julio C. Videla, Rosa Dzioba

"This paper reports the hydrometallurgical treatment of gravity concentrates of gold samples and outcrops associated with graphite ores obtained from:• flotation tailings of crystalline graphite minerals• outcrop samples of graphitic rock associated with auriferous minerals and free gold located in the Villa Union district and surrounding areas - La Rioja Province - Argentina.Previous studies of the flotation potential of crystalline graphite minerals failed to consider the presence of noble metals.The samples represent a mineralized zone of crystalline graphite which is distributed in different formations with a NE - SW trend in Maz, Punta Colorada and Las Ramaditas hills, covering an area of about 300 square kilometers."

Jan 1, 2003

By John Ralston, Jonas Addai-Mensah, Patience Mpofu

The flocculation and dewatering behaviour of kaolinite (non swelling) and smectite (swelling) clay dispersions has been investigated using hydrolysable metal ions Mn(II) and Ca(II) and anionic polyacrylamide-acrylate copolymer (PAM) at pH 7.5 and 10.5. A pH-dependent, specific metal ion adsorption behaviour, accompanied by a marked reduction in particle zeta potential and slurry shear yield stress, was observed to have a profound influence on the colloid stability of both types of clays. Due to the differences in the cation exchange capacity, the smectite clay dispersion required a higher amount of metal ions than kaolinite dispersion to produce similar effects. The adsorption density of the anionic PAM at the negatively charged clay particle surfaces correlated well with metal ion hydrolysis and adsorption behaviour, all of which had a strong effect on slurry settling rate and extent of consolidation. At pH 7.5 where Mn(II) ions hydrolyse, metal ion and flocculant adsorption densities were both greater in the presence of Mn(II) than Ca(II) ions. At pH 10.5, however, where Ca(II) ions begins to hydrolyse, higher adsorption densities were observed for Ca(II) ions in comparison with Mn(II) ions, as the latter hydrolysed completely and precipitated. The metal ion mediated flocculant adsorption led to improved hydrogen bond driven particle bridging and facilitated charge neutralisation flocculation mechanisms which significantly enhanced the dewaterability of both clay dispersions.

Jan 1, 2003

By P. Holtzhausen, L. Auret, B. Lindner, A. Haasbroek

"Spiral concentrators offer a cost effective way to separate valuable minerals from gangue by displacing lighter materials to the outside, and heavier materials to the inside of the spiral. The separation can be seen as visible concentrate bands and splitters are set at the bottom of the spiral to effectively split the ore into various densities. As there are typically many spirals in a concentrator plant, it becomes ineffective to continually adjust the splitter positions manually. Vermaak et al. (2008) proposed to use image recognition to detect the concentrate bands, thereafter, creating a model predicting the positions under certain input conditions. This model could then be used for optimisation and/or control of splitter position or band position. In contrast an online concentrate band detection system would provide real time concentrate band positions without losing accuracy due to model generalisation. These systems are usually expensive and time consuming to develop, due to a lot of centralised features required (image capturing, image processing and/or feedback to a controller). This study took advantage of the recently developed Raspberry Pi minicomputer to perform rapid prototyping of an online image processing sensor. The Raspberry Pi, and accompanying camera module, offers a portable Linux environment which can natively run the required image processing algorithms. Furthermore, extensive use of OpenCV was made to reduce development time, by relying on existing and proven algorithms to detect the concentrate bands. The Raspberry Pi also incorporates generic input/output ports which can be used in future work to provide the signal to a controller. In conclusion, the Raspberry Pi was successfully used to perform real time concentrate band position detection on a spiral concentrator. This solution is more general than an experimentally identified input-output model and may be used for control or optimisation studies in a wide array of spiral concentrators."

Jan 1, 2014

By H. Deng

Oxidized zinc ores are the main source of zinc metal except sulfides. To have a better understanding about the performance of smithsonite and the main gangue, quartz, in flotation, the aggregation behaviors of smithsonite and quartz in water were confirmed by different techniques (sedimentation tests and optical microscopy). The experimental results show that smithsonite and quartz particles aggregate in the pH range 7.5-11. The results of zeta potential suggest that the aggregation does not correlate with the DLVO theory, when the iso-electric point of smithsonite and quartz is 8.0 and 2 respectively. When the solution pH is less than 8.0, smithsonite has an opposite charge to the quartz particles. Electrostatic adsorption makes effort on these two kinds of particles according to DLVO theory. Whereas, solution chemistry calculation shows the pH range 8-11 corresponds to hydroxide formation, suggesting that this is the species responsible for aggregation. And their concentrations are much higher in sodium hydroxide system than that in sodium carbonate system. Aggregation of smithsonite and quartz due to the flocculation action of zinc hydroxide is proposed.

Sep 1, 2012

By Xubo Chen, Zhiqiang Hu, Zhijian Sun, Gaoyun Zhou

"The research aimed at developing an efficient and environmental frother,which was applied in the flotation of sulfide ores. The flotation properties of an efficient frother and pine oil have been studied relatively by flotation tests of lead and zinc sulfide ores. At the same time, the biodegradability of two kinds of frother has been studied by the method of biological respiratory curve. The test results show that the flotation properties of new frother are superior to pine oil such as flotation rate, dosage etc. and its biodegradability is superior to pine oil. INTRODUCTION Frother is a kind of important agent in flotation reagents.In practice, the criterion of the foaming performance of the frother is what is high and low according to flotation indexes. The difference of different minerals and flotation technologies has great influence on the foaming performance of frother, and it is very important to choose the corresponding frother. The type, dosage and selectivity of frother in flotation process must be considered carefully. In today's society, environmental protection and ecological protection are becoming more and more important, and the environmental and ecological damage from mine development has aroused increasingly more attention. The use of mine agents has promoted the development of mineral resources, greatly improves the recovering utilization of mineral resources, at the same time, the production and use of mine reagents also inevitably bring about pollution, and result some influence or damage in the ecological environment.The frother is a common kind of reagent in the flotation process of the concentrator. In many cases, the waste water in the concentrator can not be let out in the natural water because the higher content of the frother in the waste water results in higher index of COD.This will inevitably increase the cost of waste water treatment in the mine.Therefore, the choice of frother should not only consider its influence on the flotation index, but also consider its influence on environmental protection. Waste water treatment is a way to solve the waste water pollution, but it needs to cost a lot of fund, manpower and material resources.And the development of high efficiency pollution-free reagent is a good way to reduce the production cost of mining enterprises and reduce the environmental pollution."

Jan 1, 2018

By C. Y. Sun

Flotation of chalcopyrite and unactivated malachite with xanthates (ethylxanthate, butylxanthate, octylxanthate and dodecylxanthate) is studied in this paper. Minerals interacted with xanthates are detected by FTIR, and simulated by molecular mechanics. It shows that chalcopyrite can be floated with 4 kinds of xanthates, and unactivated malachite can?t be floated with ethylxanthate but can be floated directly with later 3 kinds of xanthates while characteristic absorption peaks of those four kinds of xanthates are all detected by FTIR on chalcopyrite and malachite surface. After simulating the interaction between xanthate and mineral, it shows that H2O and OH-can interact with chalcopyrite and malachite, and their interaction energy may be so called energy bulwark which must be overcome by collector when collector interacts on minerals; the two sulfur atoms in xanthate group interact with copper and neighbor iron atoms on chalcopyrite. It also shows that molecular mechanics results with logP of collectors can interpret the mechanism of xanthate-mineral on atom scale.

Jan 1, 2014

By Andrew D. McCallum, Russell A. Heins

"Until the advent of intensive cyanidation, gold gravity concentrates were generally treated by tabling. The table concentrates were smelted while table middlings and tailings were recycled to the milling circuit for further grinding and subsequent leaching in the CIP/CIL circuit. Gold recovery on production tables is relatively low, often only 30 percent, and rarely above 60 percent. Significant factors in tabling performance are; mineralogy and the operator’s experience and ability. Units have been developed by Gekko Systems to treat both batch and continuous gold concentrates. Unit sizes are determined by leach kinetics and the required residence time of the concentrate in the unit.Gekko commenced the commercialisation of intensive leaching of gravity gold concentrates in 1997 with the first commercial prototype of the InLine Leach Reactor (ILR). Over 20 units are now installed worldwide with half that number on the African continent. South African mines, South Deeps (Placer Dome WAJV) and Target (AvGold) have both installed InLine Leach Reactors. Ashanti Goldfields have placed the ILR on their standard equipment list and have six operating units with a seventh on order. AngloGold installed one of the first ILR production units at Morila in Mali.Gekko Systems successfully installed an ILR1000 Batch unit at the Antapite Mine in Peru in December 2002. The unit was installed to treat gravity concentrates and to replace a shaking table. Following installation, gravity gold recovery increased from 15% to 40% of total gold. The unit was operational from start up and the first gravity batch treated achieved 98% gold recovery. The gravity concentrates also have a high silver content and 95% recoveries on silver were also achieved.Preliminary testwork identified that the concentrates required additional oxygen to achieve peak performance. As a result of optimisation work in the laboratory, leach kinetics in the ILR have been excellent with only 6 hours residence required to achieve maximum gold extraction."

Jan 1, 2003

By Jia Muxin

The adsorption behaviors of metal ions on a silicate mineral and the flotability of a metalized silicate mineral with sodium oleate as collector are closely related to the structure of the silicate mineral. The adsorption isothermals of the metal ions on different silicate minerals are studied, the parameters of the isothermal give the information how many surface oxygen anions a metal ions is attached to, from this information and the structure of the mineral the site where a metal ion is attached can be guessed (The adsorption isothermals and adsorption behaviors with pH are fitted with Temkin, Frenudlich and Kurbatov equations respectively). Metal ions as Cu2+, Ni2+, Zn2+ are attached to the oxygen anions of surface species –Si-O– on the quartz surface, most of them coordinate to only one surface oxygen, their adsorption ability on quartz is low, but this metal ions on quartz surface protrude out of the surface perfectly, so their ability to combine with oleate acid radical is excellent. Quartz can be activated well by such metal ions. The isothermal of Fe3+ on quartz indicates these cations coordinates with more than two surface oxygen anions. This means the Fe3+ nucleates on quartz surface in the form of Fe(OH)3 colloid particles. The isothermals of Cu2+, Ni2+, Zn2+ Fe3+ on spodumene shows such ions coordinate with more than two surface oxygen anions, it indicate these ions may attach to the position where Li+ is formerly exists, such metal ions stay in a cave on the mineral surface, their adsorption abilities on spodumene are quite well, but they are affect by the oxygen anions of the two Si tetrahedron chains, the can almost not activate this mineral. These cations may attach on the site where Al3+ exists on the muscovite surface, just like spodumene, muscovite can not be activated well by such cations. Pt2+ has a large ion radius, as Pauling’s rules depicts polyhedron can not attach to Si tetrahedron well, the adsorption ability of Pt2+ on quartz is low and quartz is activated badly by Pt2+. On the other Pt2+ can adsorb well on spodumene and muscovite well and activated them well because it is not affected so bad by the tetrahedron oxygen anions of the minerals for their its large radius. The isothermal of Ca2+ on quartz indicates a Ca2+ coordinates with less than one surface oxygen anion, this means Ca2+ attaches on quartz mainly by physical adsorption. The adsorption abilities on mineral surface and the interaction abilities with oleate acid radical of the transition metal ions with the same valence are guessed to be determined by their d electron number, the rules should be d1<d2<d3<d4>d5<d6<d7<d8<d9>d10. Hydrogen bond may play an important rule in the activation of the mineral by HF and the interaction of the HF activated silicate mineral with collectors. The general rule is high bond valence and small metal ion radius surface species –Me-O can be activated well by HF with sodium oleate as collector. For example – SiIV-OH is neutral while –SiIV-FH+ and –SiVI-FH+0.33 are positively charged, the positively charged surface species are more likely to connect oleate acid radical via hydrogen bonds.

Jan 1, 2003

By Ljudmil S. Grigorov, Eric Forssberg, Hanumantha Rao Kota, Robert J. Pugh, Lidia B. Alexandrova

"The effects of mixed collectors on some physicochemical parameters (thin film lifetime, kinetics of expansion of the three-phase contact, equilibrium three-phase contact angle and surface tension) involved in the elementary act of flotation were investigated experimentally.We have used the microscopic thin balance developed by Scheludko et al (1970) to study the stability and interactions within the thin film between the silica surface and air bubble with (i) a long chain C10 amine and (ii) a cationic/anionic surfactant systems consisting of mixtures of a long straight C10 chain amine with long straight chain C8, C10 and C12 sulfonates at 1:1 molar ratio. The experiments were performed at a range of concentrations at pH 6.5. The equilibrium contact angle was measured with a microscope technique using the modified Mingins-Sheludko method (Mingins and Scheludko, 1979). The surface tension was measured by the method of Wilhelmy (Adamson, 1960). It was found that the mixed surfactants caused lower contact angles, lower rates of the thin film rupture and longer film lifetime, compared to the pure amine system."

Jan 1, 2003

By Hamid-Reza Manouchehri

"The triboelectric charge attributes of some silicate minerals (i.e., feldspar, quartz and wollastonite) after contacting different triboecharging medium made of different materials were studied. The charge acquisitions by different size fractions of minerals were monitored and accordingly the energetic work function values, i.e., the main parameter determining the entity of triboelectric charges acquired by mineral grains, of the examined minerals were estimated. Moreover the separation behavior of different size fractions of these minerals through the electric field of a laboratory free-falling separator when the mineral grains are charged by different tribochargers were observed and considered as the electrical separation potential of the examined minerals.Furthermore, the role of adsorption of different chemical species on triboelectric charge characteristics and charge acquisition of mineral samples were described from theoretical point of view and the effects of some chemical reagents on triboelectric charge acquisition of the examined minerals were studied. In addition the separation behavior of chemically conditioned quartz, feldspar and wollastonite minerals, using different anionic and cationic reagents, through the electric field of a free-fall electrostatic separator before and after chemical conditioning were monitored.Finally an attempt was made to translate the findings from single mineral systems to a complex silicate ore, containing mainly of feldspars, quartz, and wollastonite. Different separation tests under various conditions were conducted to this complex silicate ore. Before passing through the separation device, the ore sample was conditioned by different cationic and anionic reagents and then was triboelectricaly charged by different tribocharging medium in order to find the effective reagent and tribocharging medium for separating silicates. Besides the role of temperature and humidity of the surrounding ambient in separation behavior were considered."

Jan 1, 2003

"The Merensky Reef is a platinum group minerals (PGM) bearing reef in the Bushveld Igneous Complex in South Africa. The reef has been treated by bulk PGM and sulphide flotation with the aim of maximisingthe valuable minerals recovery and gangue minerals rejection.Synthetic water with a calcium concentration of 80 ppm and 500 ppm was prepared and the flotation results obtained were compared to a simple electrolyte in order to determine the effect water quality has on pentlandite and pyroxene surface alteration and, ultimately, floatability. During the study, the possible effect of interactions between the minerals investigated and Ca2+ ions in the presence of sodium isobutyl xanthate was studied at pH 6 and pH 9 by means of zeta potential determinations, microflotation tests and ToF-SIMS analysis.The results obtained on 1:1 pentlandite-pyroxene mixtures showed that the quality of process water plays an important role in flotation. The flotation recoveries of pentlandite and pyroxene were lower in synthetic process water compared to those obtained in a simple electrolyte solution."

Jan 1, 2003

By H. B. Zhou

The process of bioleaching marmatite using moderately thermophilic bacteria has been studied in this research by comparing marmatite leaching performance of mesophilic bacteria and moderately thermophilic bacteria and valuating the effect of venting capacity on marmatite leaching performance of moderately thermophilic bacteria and the effect of pulp densities on marmatite leaching performance of moderately thermophilic bacteria. The results show that moderately thermophilic bacteria have more advantages over mesophilic bacteria in bioleaching marmatite. Aeration agitation can improve the transfer of O2 and CO2 in solution and promote the growth of bacteria and therefore, enhance the leaching efficiency. With the increase of pulp density, the total leaching amount of valuable metals increased, however, the extraction efficiency decreased due to many rea-sons, like increasing shear force that results in poorly growth condition for bacteria, etc.

Jan 1, 2014

By Choi Sang-Ken, Chung Hun-Saeng, Kim Byoung-Gon, Park Chong-Lyuck

Fine grinding of crystalline graphite was conducted using a dry attrition mill with a vacuum system to investigate the characteristics of size reduction. Low pressure and high temperature conditions in the grinding mill were found to greatly improve the efficiency of the size reduction of graphite. Natural flaky graphite of .100 mesh was ground into sub-micron sizes, then over 90% of the product were able to be reduced below 1?without disrupting their crystallinity in a short period of time. Reducing the atmospheric pressure in the grinding environment promotes the removal of chemical species such as oxygen and water molecules adsorbed on the graphite particle, resulting in effective size reduction while maintaining the crystallinity of graphite.

Jan 1, 2003