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By H. M. Gao

According to the difficulty of dolomite removal from collophanite,normal-reverse floatation process has been adopted in floatation with the use of highly selective collector G-4 and depressant S721. Good indexes of flotation have been obtained with the run-of-mine ore containing 17.96 % P2O5 and 2.31 % MgO being upgraded to a concentrate containing more than 30% P2O5 and less than 1% MgO. The reagent interaction mechanism in low grade collophanite flotation has been stu-died by FTIR analysis and theoretical calculation. The results indicate that the interaction between collector G-4 and collophanite is the result of chemical adsorption in combination with physical ad-sorption with chemical adsorption playing the major role. Depressant S721 adsorbs on dolomite surface to form a water film and effectively depresses the flotation of dolomite and reduces the MgO content in the concentrate.

Jan 1, 2014

By In-Kuk Bae, Kwang-suk You, Joobeom Seo, Kwanghyun Bea, Hyung-Seok Kim

Arsenic in base metal sulfide ores is highly penalized owing to high costs for its control in metallurgical processing. The arsenic element in the lead-zinc ore, which is target ore in this study, has been shown to be in the form of arsenopyrite. Experimental work in this study is about arsenic rejection flotation, using depressant suitable for the removal of arsenopyrite from the Pb concentrate. The arsenic rejection flotation also included the oxidation treatment of Pb concentrate with H2O2. In this study, the Pb concentrates containing 80.7% Pb and 0.25% as was obtained with the additions of aluminosulfate as arsenic depressant. And through IR measurement, it was also known that the addition of aluminosulfate during arsenic rejection flotation formed calcium aluminosulfate hydrates on the surface of arsenopyrite particle, resulting in rendering arsenopyrite hydrophilic.

Jan 1, 2014

By T. Lang

Clay sorbents from the North Bohemian Brown Coal Basin represent important but still some-what neglected accessory raw material. Submitted paper is concerned with relation between mineral structure, sorptive efficiency and reclamation exploitation of these rocks. Characters and localities of main clay sorbents from the North Bohemian Brown Coal Basin are shortly evaluated in an introduction. In next part, methodology of mineralogy survey for these accessory raw materials is stated, it is based on diffract analyse with D 5000 Siemens X-ray diffracto-meter. At the conclusion results are stated of mineralogy analyses from several clay sorbents. The determination of the zeolite and montmorillonite localities was accentuated. The paper presents also possibilities of practical clay sorbents utilization, especially by reclamation works.

Jan 1, 2014

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 P. T. L. Koh

The effect of particle shape on the flotation process has been investigated in laboratory experiments with monosized spherical ballotini and roughly ground ballotini. The particles were treated by partial methylation with trimethylchlorosilane to achieve varying degrees of hydrophobicity. In flotation, the process of film thinning and liquid drainage is critical in the formation of a stable bubble-particle attachment and this is affected by the particle shape and surface hydrophobicity. The rate of attachment affects the overall flotation rate. Flotation tests with different particle sizes at various degrees of partial methylation have been performed in a modified Denver cell. Predictions from a computational fluid dynamic model of the cell which incorporates fundamental aspects of bubble-particle attachment are compared against flotation test results. Contact angles of the particles have also been measured using the capillary rise technique to indicate surface hydrophobicity.

Jan 1, 2014

By X. G. Liu

Bentonite is an excellent sealant mineral material because of its desirable swelling and self-healing characteristics, low permeability, sorptive qualities, and longevity in nature. A new type of water-swelling building sealant made from bentonite was studied in this paper. The building sealant is prepared by Na-base bentonite, vaseline and paraffin wax under different mass fraction of bentonite (which is 60%,65%,70% respectively). Under unrestricted state, some properties of samples were investigated. The volume expansion ratio at 24 h is 211%, 222%, 256% , and permeability coefficient is 2.86×10-8 cm/s, 4.15×10-8 cm/s and 4.78×10-8 cm/s respectively; low temperature flexibility of the sample (bentonite quality is 65%, 70% respectively) is good, and it does not flow heated for 2 h under 80?. The results of XRD and SEM indicate that bentonite is coated preferably by vaseline, and the spacing of layers of bentonite do not changed. The sample can keep full water swelling ability, and has good molding process. The test results prove that the properties of samples may reach the standard of building sealant.

Jan 1, 2014

By L. A. Vaisberg

"Mining processing plants are the most high-performing industrial enterprises in the world economy system. Even at an average-scale mining enterprise, the grain-size separation equipment continuously processes 105 to 106 dissimilar mineral particles per hour. In separation by physical properties, their number increases by at least 10 to 50 times. Mathematical modeling of such a high flow of discrete particles is carried out using two different approaches: the discrete-particle and the phenomenological methods. The calculations demonstrate the possibility of handling big data when describing the processes of separation of granular material. INTRODUCTION The interest to the screening process and the process of formation of new screen designs in Mekhanobr is traditional since the moment of its foundation. It is symbolical that the first publication of the Mekhanobr proceedings in 1924 was the monograph dedicated to screens and screening products as such, which was the first one in the world at that moment. It was a book of Prof. L. B. Levenson, one of the founders of Mekhanobr, who headed the Technical Bureau of the Institute. Vibratory screening is the most mass process in the technologies of solid minerals processing, which determines significantly the energy demands of crushing and grinding cycles, and at some enterprises determines the quality of the final product, for example in case of crushed stone, coal or abrasive materials production. The general understanding and simulation of the process of poly-dispersed granular materials vibratory screening was developed at several conceptual levels taking into account the features of classification of materials with different size and density.Considering the real industrial processes of vibration screening, it shall be noted that at the sieve surface of the screen in the initial part of the deck the classification in a thick material layer (in natural conditions) occurs, which further transfers to a thin layer (free movement). In the process of screening of light minerals, for example coal or metallurgic feedstock, screening is mainly performed in the thick layer."

Jan 1, 2018

By F. S. Niu

With the feature of finely-dissemination particle and complex mineral composition, oolitic hematite is considered to be the ore dressing difficult problem in the world. Series research on refractory oolitic hematite in Zhangjiakou Area are introduced as following: ore properties?technology mineralogy and mineral processing technology. The survey shows: with the fine grinding of the hematite to a fineness of -0.076mm 95%, obtaining iron concentrates grading 62.74% Fe at the recovery of 46.80% by high intensity magnetic separation- reverse flotation flowsheet; under the three stages intensity magnetic separation,four stages grinding and four stages gravity separation, getting the iron concentrates grading 61.09% Fe at the recovery of 45% using high intensity magnetic separation- gravity separation flowsheet; with roasting temperature of 800°C, time for 75~90min and ore-coal ratio of 11, gaining the iron concentrates assaying 62.74% Fe at the recovery of 87% by roasting- magnetic separation flowsheet. At present, this research is still doing for the target of raising the concentration recovery on the base of high grade concentrate. It is in the hope of fully utilizing the existing hematite resources in Zhangjiakou

Jan 1, 2014

By Roberto Galéry, Braz J. C. Filho, Marcelo M. Stopa, Douglas B. Mazzinghy, Priscila M. Esteves

"The purpose of the research is to monitor ball mill filling by means of signals usually measured in its electrical drive. The method is based on the mill torque estimated from rotor speed and induction motor stator voltage and currents. New signal processing is presented in both time and frequency domain for measurements in a dry laboratory ball mill. Statistical analysis is applied to time series resulting in good correlation to mill filling. Fast Fourier Transform (FFT) and power spectral density (PSD) also resulted in an accurate filling indicator. The proposed method does not need any sensor to be installed directly on the mill and requires only sensors usually available for motor control purposes. The experimental results showed that the method have potential to be used to construct an automatic system for monitoring operational variables in ball mills. The aim of this monitoring is to improve energy efficiency, reliability and productivity.INTRODUCTION Recently, a great number of papers have pointed the importance of ball mill filling monitoring and also of grinding control (Lu, et al., 2014) (Ramasamy, et al., 2005) (Tsamatsoulis, 2014) (Zhou, et al., 2009). Additionally, great amount of control techniques have also been presented with several complexity degrees (Tsamatsoulis, 2014). According to Eremenko (2015) the lack of effective and accurate methods for fill level measurement is the main reason that makes mill optimal control so complicated. It happens because nonlinearity, long time delay and time varying features of the ball mill turns difficult to develop a truly efficient method for monitoring filling. At the same time, fill level has a determining role in charge motion and consequently on particle breakage. For low levels of filling many energy is expended in impacts with very low breakage efficiency. Those impacts can also damage mill liner. In contrast, high levels of filling causes damping effects that reduces breakage and can also affect energy consumption. Based on this it is conclusive that fill level measurement of ball mills is an important issue for grinding efficiency. This fill level information can be used for operators to control ball mills and also for engineers to run simulations and improve confidence levels of circuit designs (Shi, 2016)."

Jan 1, 2018

By M. P. Krasteva

The froth flotation process for separation of mineral ores depends on the establishment of care-fully controlled froth. The formation of very stable froth in the flotation circuit is a problem that may occur in many plants, resulting in down-time, low quality and grade of final product and considerable expenses. Froths build up on the top surfaces of thickeners, tanks and flotation cells until they overflow, or until the efficiency of the circuit is impaired. A similar problem exists in Assarel concentrator, Assarel-Medet PLC, Bulgaria. Copper and copper-pyrite ores are dressed in Assarel concentrator. They are characterized with variable and complex mineral and physical composition. During the flotation cycle, resilient and difficult to break-down froth is formed, which subsequently impedes the process of thickening and clear overflow obtaining. Due to this problem continuous sampling in the cycle of thickening was conducted. The mineralogical, chemical composition, particle size distribution and solid phase content of the products were determined. It was established that the solid phase of the froth build up on the top surface of the thickener differs considerably from this one of the thickener underflow. The data clearly indicates that a separation process takes place on the top surface of the thickener ? fine particles of chalcopyrite are concentrated in the froth. The role of chemical reagent addition in the break-down of the flotation froth is investigated in terms of surface chemical phenomena involved in the stabilized froths. Measurements of the coper minerals wettability and surface tension at the air/liquid interface were performed. The surface active agent AERODRI® dewatering aids were laboratory tested. Bench-scale froth collapse tests were conducted. Reagent addition into pulp-froth system promotes and leads to a bubble coalescence, an improvement of the wetting of the mineral particles and a decrease of the surface tension at the air/liquid interface. The results of the laboratory experiments showed that the presence of the surface active agent leads to considerably decrease of the froth stability and the destruction of the deleterious froths build up on the top surface of the thickeners in Assarel concentrator.

Jan 1, 2014

By A. Vidyadhar

Printed circuit boards (PCBs) constitute a majorpart of electrical and electronic equipment containing valuable metals such as Cu, Ni, Au, Ag, Pd, Fe, Sn, Pb, etc. The concentration of base and precious metals in PCBs is observed to be several times more than those in their respective ores. Therefore, the recycling of PCBs is necessary to recover the valuable materials. However, the ultrafine particles pose a big challenge. Removal of them is suggested prior to processing by flotation. Froth flotation is observed to be a promising technique for rejecting the plastics from the comminution product. In the present work, enrichment of ground 1.0 mm PCB powder was investigated through flotation route by varying the operating variables such as frother dosage, pulp density, air flow rate and rotational speed of the impeller. The liberation studies indicate that excellent liberation of metal values is achieved from the non-metallic constituents at -1.0 mm size and below. The particulate system is quite rich in metal value with about 23% total metal content. The non-metallic constituents such as plastics are observed to possess strong hydrophobicity while the metal particles in the pulverized mass are hydrophilic in nature. Froth flotation kinetics is studied in depth with a view to facilitate high rejection of plastics and identify optimum operating conditions for the same. A number of experiments are performed to establish the influence of the operating variables on flotation performance. The conditions for achieving higher yield of the metal-rich fraction with respect to a specified grade are discussed in the light of the experimental results. It is found that the requirement of reagents is negligible which could be a very important factor from the commercial stand point. Single-stage flotation increases the metal content from 23% to over 32% with a mass yield of around 75% and over 90% recovery of metal values. 32% of the materials in the feed could be effectively rejected in the float fraction losing less than 4% metal values. The dependence of kinetics on the process variables is also discussed. It was concluded that a high rotor speed helps in efficiently rejecting the plastics. Frother should be added to help stabilize the froth and enhance the kinetics. A moderate air flow is required while pulp density must be kept low for efficient pre-concentration. It is established that the entire -1.0 mm comminution product could be treated by flotation for generating a pre-concentrate. Keywords: printed circuit boards, recycling, froth flotation, kinetics, recovery

Sep 1, 2012

By S. Liu

With the development of global economy, the demand of mineral?s quantity and quality are in-creased, valuable minerals are more and more finer and poorer, and the capacity of concentration plant are more and more high. Using large-scale flotation cells can obviously enhance the capacity of treating the mineral, reduce the cost, and increase the economic benefit and competitive ability for the enterprise. BGRIMM advanced advisable technical scheme with optimally parameter and route for the feature of dynamic in large scale flotation machine, and developed the KYF Large Scale Flotation Cells, which have used more than 400. The paper advanced the history, the design principle, the operating principle, the structure feature and the application of KYF flotation ma-chine.

Jan 1, 2014

By Elves Matiolo

This paper describes, in detail, results obtained from a research study of a complex iron ore aiming to produce a pellet feed concentrate with at least 65% of Fe and less than 3.5% of SiO2 in the final concentrate. The work includes an ore desliming followed by column flotation at laboratory scale. The ore sample was from Carajás province - Brazil and represents a complex low grade compact itabirite ore, analyzing 35.9% Fe, 45.1% SiO2 and 0.57% of Al2O3. Yet, the feed was treated previously by magnetic separation and grounded to 97% < 20 µm; this sample was named MAG 2. The chemical and mineralogical characterization of the MAG 2 sample showed that Fe and SiO2 grades were 50.7% and 24.3% respectively and was composed mainly by hematite, goethite and quartz. The particle size distribution, using a laser diffraction technique, showed that 90% of the particles were < 18 µm; 50% less than 8 µm and 10% minor than 1 µm. When the cationic reverse flotation without desliming was tested the selectivity of the process was very low and did not meet the concentrate metallurgical goals of the pellet feed product. However, when desliming was applied prior to flotation, a concentrate product with chemical characteristics of the pellet feed was obtained. The best results after desliming and column flotation achieved global iron metallurgical recovery of 72% with Fe grade in the concentrate of 66.5% and 2.1% SiO2 using starch as depressant for the iron oxides minerals at 1200 g/t ? 1500 g/t and an amine as the quartz collector at 100 g/t concentration (pH constant, at 10.5). It is believed that the desliming stage was key in the separation of the iron bearing particles and has a high potential for the flotation process of this type of ores.

Sep 1, 2012

By James D. Bittner

Separation Technologies, LLC (ST) has developed a processing system based on triboelectric charging and electrostatic separation that provides the mineral processing industry a means to beneficiate fine materials with an entirely dry technology. The environmentally friendly process can eliminate wet processing and required drying of the final material. The process requires little if any pre-treatment of the material other than grinding and operates at high capacity ? up to 40 tonnes per hour by a compact machine. Energy consumption is low, approximately 1 kWh/tonnes of material processed. Since the only potential emission of the process is dust, permitting is typically relatively easy. In contrast to the other available electrostatic separation processes that are typically limited to particles greater than 75 µm in size, the ST belt separator is ideally suited for separation of very fine (<1 µm) to moderately coarse (500 µm) materials with very high throughputs. The triboelectric particle charging is effective for a wide range of materials and only requires particle ? particle contact. The small gap, high electric field, counter current flow, vigorous particle-particle agitation and self-cleaning action of the belt on the electrodes are the critical features of the ST separator. The high efficiency multi-stage separation through charging / recharging and internal recycle results in far superior separations and is effective on fine materials that cannot be separated at all by the conventional electrostatic techniques. Since 1995, this triboelectric process has been extensively used for the beneficiation of coal fly ash with eighteen separators in place and over 100 machine-years of operation at locations in the North America and Europe. The technology has been also successfully applied to the beneficiation of a variety of minerals including calcium carbonates, talc, and potash.

Sep 1, 2012

By Ana Elisa Casas Botero

The Rhodococcus opacus microorganism was evaluated as a biocollector for flotation of barite. The electrophoretic behaviour of the mineral, before and after R. opacus interaction, was evaluated and showed that the cells adhesion shifted the mineral zeta potential curves. Adhesion tests were suggested a high affinity of the bacteria for barite. The experiments of the adsorption rate of the R. opacus on the mineral surface showed fast kinetics, achieving a maxim of cell adsorption after 5 minutes. Adsorption isotherm curves for barite could be categorized as Langmurian (L) type II. The best bioflotability results for barite achieved values around 75% for a R. opacus concentration of a R. opacus concentration of 250 ppm in the pH around 5.0. The studies were compared with the flotation of barite using a traditional collector. The bioflotation experiments were discussed considering the obtained adhesion tests. The results were supported by the Thermodynamic approach for selected pH values. The fundamental flotation studies showed the paramount potential that R. opacus presents as a biocollector and its possible application in the mineral flotation industry.

Jan 1, 2014

By Z. A. Zhou

In Canadian oil sands processing, flotation is used to recover liberated bitumen droplets from oil sands slurries. Similar to conventional mineral flotation practice, a fundamental limitation of recovering bitumen from low grade oil sand ores is its slow and ineffective aeration of the liberated small bitumen droplets. Gas nucleation and cavitation could provide better mechanisms for accelerating bitumen-bubble attachment. A research program was undertaken to examine factors affecting spontaneous bubble nucleation on bitumen surfaces. The results demonstrate that surface hydrophobicity and existence of gas nuclei in process water play a critical role for bubble nucleation. While there are more bubbles nucleated on highly hydrophobic silanated glass surfaces than on moderately hydrophobic bitumen, bubble nucleation on clean hydrophilic glass surfaces is negligible. Heating process water up to 85 ~ 95oC (as used in commercial operation) or boiling tap water prior to gas nucleation tests is shown to remove sufficient amount of gas nuclei existing in the water, thereby drastically reducing the number of bubbles nucleated on bitumen. Enhancing gas nuclei formation in hot process water is identified as a promising strategy to improve bitumen-bubble attachment during oil sands conditioning, and hence to increase bitumen recovery from low grade ores.

Jan 1, 2014

By Z. M. Dai

Microorganisms in AMD (Acid Mine Drainage) were enriched in 9K culture medium. The enrichment was applied to leach copper pyrite after the microbial community structure and metabolism was stable. Before and after bioleaching, the microbial DNA was extracted and applied to RFLP (restricted fragment length polymorphism) analysis to demonstrate the relationship between the leaching efficiency and the change of microbial community. Atomic absorption spectrometry results showed that when concentration of the pulp was 10% and pH were 1.5, 2.0 and 2.5, the leaching rate were 56%, 57% and 34% on the 18th day respectively. These results indicated that the rise of pH resulted in the decrease of leaching rate. In lower pH condition, the growth of microbe was faster: when pH was 1.5, the microbial cell number reached to 1.4×107cells/mL on the 9th day; while pH was 2.5, the microbial cell number decreased to 4×106cells/mL. The analysis of microbial community structure showed that Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans were dominant species before bioleaching (account for 43% and 32% respectively). And after bioleaching, these two species were still dominant when the initial bioleaching pH were1.5 and 2.0. While the initial bioleaching pH was 2.5, the proportion of these two species decreased. These results demonstrated that the initial bioleaching pH would affect the microbial community structure in bioleaching system at room temperature, and this affect could lead to different copper pyrites bioleaching efficiency.

Jan 1, 2014

By H. J. Wu

The optimum performance in mineral processing plants usually demands the optimum size reduction, which is frequently achieved by a closed grinding circuit. Due to the difficulty associated with fine size classification, the size separation efficiency in closed grinding circuit is usually very low, which leads to huge circulating load and significant overgrinding. Recent development of Der-rick Stack Sizer has made an efficient fine size separation down to 200 mesh with a satisfactory screening capacity. With the efficient fine size separation with Derrick Stack sizer, the problems commonly associated with typical closed grinding circuit, including high circulating load and over-grinding, have been eliminated. Feedback from numerous Stack Sizer applications in iron ore industry indicated that, compared with conventional fine size classification equipment, the circulating load achieved by Derrick screen was usually decreased from approximate 300% down to 60% or so, while the iron recovery has been increased by 6% to 8% only by more efficient size separation in the closed grinding circuit. To study this phenomenon, this paper discusses the relationship between size classification, circulating load and mineral recovery in the closed grinding circuit. A simulation model to predict the improvement in the grinding circuit from more efficient screening is also introduced with this paper.

Jan 1, 2014

By T. Wajima

We tried to convert paper sludge ash (PSA) into zeolitic product with high cation exchange capacity (CEC) through acid leaching. Typically, PSA from incineration of paper sludge contains a high percentage of calcium in the form of anorthite (CaAl2Si2O8) and gehlenite (Ca2Al2SiO7). It is difficult to convert the ash with a high Ca content into zeolites, or at least into more desirable zeolite phases. Acid leaching with HCl was applied to reduce the Ca content to synthesize zeolitic product with high CEC. The raw ash was treated with 1 M, 3 M, and 5 M HCl solution for 0.5~24 hours (the ratio of the ash to volume of HCl solution was 1/4), and then zeolitic product was synthesized from leached ash through the reaction with 2.5 M NaOH solution at 80 oC for 24 hours. During acid leaching, gehlenite is readily dissolved in a lower HCl concentration solution than anorthite. With increasing HCl concentration, the amounts of Ca, Mg, Si, Al, Fe and Ti extracted from the ash increased. Ca and Mg contents were easily extracted from ash than other elements. The contents of Ca and Mg extracted rapidly at initial stage, and then levelled off. The saturation times of Mg and Ca are almost 0.5 h using all concentrations of HCl solutions. After the synthesis from leached ashes, zeolite-A and -P were synthesized from ash leached in 1 M HCl solution, and 3 M and 5 M HCl solutions, respectively, regardless of leaching time. With in-creasing HCl concentration, the Ca content eluted from the product decreased, due to the removal of Ca via acid leaching before the synthesis, while the Na content eluted from the product increased to 3 M HCl and then decreased, which was almost similar to the CEC of the product, due to the ion exchange of Na-type zeolitic phase in the product. The change of zeolite phases in the product and the CEC of the product depend on the concentrations of Si and Al in the solution during the synthesis. The highest CEC of the product is about 220 cmol/ kg, which was synthesized from the ash leached in 3 M HCl solution.

Jan 1, 2014

By Tom Liu

This paper is a fundamental study of bubble-particle collision efficiency in turbulent flows. A CFD-based microscale scheme for the prediction of turbulent bubble-particle collision efficiency in a 3D isotropic turbulent flow is developed, and in this way, turbulence effects on particle-bubble collision efficiency are taken into account for the first time. By comparing the computed results with experimental data from the literature, the CFD simulation is shown to correctly predict the bubble-particle collision efficiency in a quiescent environment. The CFD method was then applied to the investigation of bubble-particle collision efficiency in a turbulent flow, and the simulation results are shown to be qualitatively consistent with the real observations. The predicted collision efficiency can be used in a multiscale modelling scheme, which would account for all control variables in a flotation cell, such as impeller structure and tip speed, air nozzle structure and air flow rate This study indicates how microscale simulations of bubble and particle behaviours, coupled to macroscale CFD simulations of flotation cells, can provide a powerful tool predicting the flotation rate in a real flotation cell.

Jan 1, 2014