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By V. Panayotov, M. Panayotova

"Wastewater from ores processing is often polluted by molybdate and sulfate (SO42-) ions. Sorption is one of suitable methods for removing those pollutants when presenting in low concentrations. This work reports results on adsorption of sulfate and molybdate ions on metal modified (with barium - Ba and lead - Pb) and organic reagent modified (with Hexadecyl-trimethyl-ammonium bromide - HDTMA) clinoptilolite. Zeolite’s modification with Pb, Ba and HDTMA increases its uptake capacity with respect to Mo(VI) at pH 3, with the uptake capacity decreasing in the order CL-Pb > CL-HDTMA > CL-Ba. Lead-modified clinoptilolite shows high uptake with respect to Mo(VI) in acidic, neutral and slightly alkaline conditions. The presence of SO42- in concentrations twice higher than the amount of Mo(VI) do not interfere with the Mo(VI) removal by CL-Pb. Zeolite’s modification with Ba and Pb renders it able to immobilize SO42- from water in the pH range 3-9. Kinetics of the uptake process is best described by the pseudo-first order kinetic equation. Increasing the initial concentrations of Mo(VI) and SO42- increases the removed amount of pollutants. INTRODUCTION Wastewater from copper-molybdenum ores processing is often polluted by molybdate and sulfate ions. Molybdenum (Mo) migrates easily in water and consequently the Mo polluted areas could extend for hundreds and thousands of meters (Ryzhenko, 2010). Molybdate anion is the only Mo(VI) species in natural water, i.e. at pH > 6.0. Its median freshwater hazardous concentration affecting 5% of the species (HC 5.50%) is 38.2 mg Mo/L (De-Schamphelaere et al., 2010). The marine water chronic toxicity (HC 5.50%) is assessed at 5.74 mg Mo/L (Heijerick et al., 2012). The predicted no-effect concentrations (PNEC) are 12.7 mg Mo/L and 1.92 mg Mo/L correspondingly for freshwater and marine water (Heijerick et al., 2012a). When sulfates present in drinking water in excess of 250 mg/L they cause a cathartic action (especially in children) in the presence of sodium and magnesium, and when the concentration exceeds 600 mg/L, diarrhea. When sulfate-rich effluents are discharged into the environment, they may increase the acidity of water bodies and soils (Guimarães and Leão, 2014). Because of the adverse effects to human health and the environment, limits are set for SO42- concentrations in waters and wastewaters in the range of 250 / 500 mg/L."

Jan 1, 2018

By Erico Tabosa

The turbulence characteristics and measurement techniques for agitated tanks are well established for liquid and liquid-gas systems. However, the literature shows that the overall energy dissipation rate (related to turbulence) is affected not only by air addition, but also by the concentration of solids. Unfortunately, there are no reliable measurement techniques for characterizing turbulence in a three phase (liquid-solids-gas) environmental system, which is the case in a flotation cell. Therefore, the effect of turbulence on flotation kinetics is very much one of conjecture. The aim of this work was to develop a sensor to characterize the degree of velocity fluctuation, which is related to turbulence, in a flotation cell operating with slurry and air. This sensor comprises a piezoelectric film transducer that converts mechanical to electrical energy. Hence, when the sensor deflects backwards and forwards an AC voltage is created. Flotation studies carried out using this sensor in a 3m3 Metso RCS cell processing a copper sulphide ore showed a highly turbulent impeller zone with transition to a significantly less turbulent zone in the upper portion of the cell. The transition region moves as the cell operating variables are changed, for instance the impeller speed, impeller size, air rate and feed solids concentration. Keywords: mechanical flotation cell hydrodynamics, turbulence characterization

Sep 1, 2012

By E. Szelag

The adsorption and stabilization of mineral dispersed systems by using Pluronic copolymers with different molecular weights and EO content has been studied. The role of sequential adsorption of EO-PO copolymers and cationic surfactant (CTAB) on the carbonate particle properties and in determining the stability of their suspension was studied with particular attention to the conformation of the polymer at the solid-liquid interface. The purpose of this work was to investigate the flocculation phenomena, influence of polymer molecular size on stability of suspensions of magnesite and dolomite and the effect of addition mode of polymer and surfactant. The suspension stability measurements and the determination of sedimentation speed were carried out using an optical analyser (Turbiscan). In most of investigated cases, the biggest floccs and the fastest sedimentation were found for low concentrations of copolymers.

Jan 1, 2014

By M. L. Liu

This work reports the results about the determination of mean activity coefficients and relative partial molar free energies for copper sulfide mineral bioleaching solutions by potentiometric method at 25ºC. The experimental potentiometric data were obtained by combining a solid state membrane-cupric ion selective electrode (Cu2+ ISE), containing a KNO3 filling solution, and an Ag/AgCl electrode. The measurements were performed in different series of copper sulfide mineral bioleaching solutions. The non-ideal behavior of the system was described on the base of the Pitzer ion-interaction model for mixed salts. Meanwhile, the relative partial molar free energies of bioleaching solution were investigated. The determination of the thermodynamic properties offers a basic data for the study of copper sulfide mineral bioleaching solutions.

Jan 1, 2014

By A. Yörükoglu

In this study, thorium mineral that found in the complex ore deposit bearing bastnasite, fluorite, and barite from Eskisehir - Sivrihisar district has been tried to extract by using HCl and H2SO4 leaching. Ore sample of approximately 3 tons taken from the ore deposit has been homogenized in order to obtain composite samples by means of ore preparation techniques for experiments. Results of chemical analyses of composite samples are as given; 40.8% CaF2, 35.35% BaSO4, 2.01 Ce, 1.5% La, 0.39% and 0.1% Th. HCl and H2SO4 leaching processes have been performed to gain Th in the ore. For determining the optimum particle size, the samples have been ground under controlled conditions and brought to the sizes of 0.065, 0.2, 1 and 3 mm. Leaching experiments have been carried out in both HCl and H2SO4 acids without roasting and roasting at the temperature of 900°C for 1, 3 and 6 h retention times for all particle sizes determined before. In the experiments, the highest Th recoveries reached are as follows; 78.74% Th when H2SO4 and 1 mm particle sized sample used, and 1 h roasting applied and 73.38% Th when HCl and 1 mm particle sized sample used, and 3 h roasting applied. Keywords: thorium, leaching, concentration, sivrihisar, roasting

Sep 1, 2012

By V. F. Petrov, O. D. Khmelnitskaya, V. M. Lodeischikov

"The processing of copper gold ores is one of the major issues of gold-mining industry in the beginning of 21st century. In this case, application of ammoniacal cyanidation process for this type of mineral raw materials deserves special attention. Irgiredmet Institute has carried out a wide range of studies on ammoniacal cyanidation process and evaluated the possible commercial use of this process for Russian operating plants. Copper gold-bearing ore from a current Russian deposit was studied. The content of gold and copper in the ore is 9.4 g/t and 0.4%, respectively. Based on the results of preliminary test work, a flow sheet was developed. It included gravity concentration followed by cyanidation of the gravity tailings using CIP. The flow sheet provides sufficient total gold recovery (91.5%). However, this technology has disadvantages, such as high specific consumption of reagents: 4.5 kg/t NaCN and 13.5 kg/t Ca(OCl)2 the ore and the increased gold grade in the liquid phase of the tails slurry (0.2 g/t). In order to improve cyanidation process parameters, test work on gravity tails processing using ammoniacal cyanidation was carried out. After the test work was completed, ammoniacal cyanidation flow sheet for copper gold-bearing ores was developed. Leaching conditions were optimized using recycled process solutions. Recommendations on gold recovery from the solutions and tails detoxification are given. The proposed flow sheet provides 91.5% gold recovery. In this case, compared to the conventional option, the consumption of cyanide decreases by 3-4 times.INTRODUCTION The technology of precious metals recovery from gold-bearing ores is based on cyanidation. This accounts for up to 90% gold recovery and the significant portion of silver (Lodeischikov, 1999). However, there exists the category of so called refractory ores. They are not amenable to direct cyanidation (without using additional expensive processes), or they are characterized by low indices of metals recovery and high consumption of reagents. The latter also include copper gold ores. Their deposits can be found extensively both worldwide and in Russian Federation. A feature of these ores is that they contain not only gold but also copper. It is considered not only as a valuable component but also as a harmful mineral impurity that hinders gold cyanidation, gold precipitation from the solutions by cementation onto zinc dust and adsorption onto activated carbon (CIL, CIP-processes), detoxification of cyanide bearing effluents."

Jan 1, 2018

By Thenepalli Thriveni, Seong-Young Nam, Nam-Il Um

New modern water treatment technologies required for arsenic removal from waste waters contaminated extensively by various background sources from mining, industrial waste, agricultural waste, painting industry and natural geological bed rock system etc. Arsenic is a widely dispersed element in the earth's crust and exists at an average concentration of approximately 5 mg/kg. Arsenic (As) and heavy metals may be released from the mine wastes to the ground and surface water systems, as well as the geological environment due to their solubility and mobility. This research focuses on the effect of accelerated carbonation process for successful removal of heavy metal arsenic anions from artificial waste water and mining waste waters. This accelerated carbonation process is a simple and novel method with 85 ~ 88% removal efficiency. Carbonation has been studied as a process to further improve immobilization of solidified/stabilized waste and granular waste. After successful removal of arsenic anions from solid mining waste and its potential benefits for producing construction materials. Besides, the industrial and urban management systems are generating bulk solid mining wastes, and most often dumping them in open fields. To prevent the landfilling with mining waste, many efforts are being made for the recycling of different types of mining solid wastes with a view to utilizing them in the production of various construction materials.

Jan 1, 2014

By Gabriel Aguilera, Juan Arismendy

"As a separator machine, the hydrocyclone is one of the most commonly used equipment in different types of industries and particularly in mineral processing, hydrodynamic behavior allows efficient separation, but developing tests to optimize experimental equipment is expensive, therefore Computational Fluid dynamics (CFD) becomes a useful tool for optimizing the geometrical and operational parameters, and allows to analyze and understand the dynamics within the equipment. In the research was developed to simulate of 40 mm hydrocyclone where turbulence model was used Large Eddy Simulation (LES) for the continuous phase, for the generation of the air core and for the interaction of particles at low concentrations was implemented (mixture model), after the simulation was completed validation and comparation was done between simulation values and experimental."

Jan 1, 2014

By M. Brozek

The particle settling velocity is the argument of separation in such processes as classification and enrichment in jigs. It characterizes material forwarded to the separation process and belongs to the so-called complex arguments because it is the function of particle density and size. i.e. the function of two simple arguments. The affiliation to a given subset is determined by the values of two mag-nitudes and the distribution of such argument in a sample is the function of distributions of particle density and size. The paper will present a method of determining the distribution of settling velocity in the sample of spherical particles for the turbulent particle motion in which the settling velocity is expressed by the Newton formula. Because it depends on density and size of particle which are random variable of certain distributions, the settling velocity is a random variable. Applying theorems of probability, concerning distributions of function of random variables, the authors will present general formula of probability density function of settling velocity for the turbulent motion and particularly calculate probability density function for Weibull?s forms of frequency functions of particle size and density. Distribution of settling velocity will calculate numerically and perform in graphical form.

Jan 1, 2014

By André Mans, Frans B. Waanders

Current losses of Ferrosilicon (Fe-Si), which is used in the dense medium separation (DMS) of iron ore at Kumba Resources, Sishen, South Africa occur due to adhesion to the separation products and also by being present in the effluent stream, due to abrasion. The losses contribute greatly to the running cost of the plant and the purpose of this project was to determine the characteristics of the unused Fe-Si and then to characterise the changes that occur during storage and the use thereof. A Scanning Electron Microscope (SEM) and Mössbauer Spectroscopy (MS) were used to investigate the characteristics of the fresh and used Fe-Si. It was found that the biggest loss of Fe-Si was due to the abrasion of the particles during the DMS process, which resulted in the liberation of Fe and subsequent formation of an oxihydroxide froth. A possible change in magnetic properties was also observed, leading to further losses that could occur during prolonged use of the medium. No clear changes to the Fe-Si occurred during correct storage methods, as was initially thought.

Jan 1, 2003

By Katja Ohenoja

Polymer dispersants, also known as grinding aids, are widely used to reduce the viscosity of mineral particle suspensions and to improve energy efficiency during fine grinding. In this study, the effect of polymer dispersant with different molecular structure on the suspension properties in the wet stirred media milling of limestone was studied. The stability of suspension was studied by combining rheological and zeta potential measurements. The PDI value of polymers corresponds to the width of the molecular weight distribution so that low PDI corresponds to narrow MW distribution and high PDI to the wide one. In this study, two traditionally fractionated polymer dispersants with high PDI (over 2) and one novel polymer dispersant with low PDI (1.2) has been tested. It was noticed that dispersants worked as electrosteric stabilizators and prevented the agglomeration of ground limestone particles. The uses of dispersants could increase solids concentration used in the grinding experiments and at the same time lower the particle size and specific energy consumption. The obtained particle sizes were about 1 µm regardless of which dispersant was used or the amount of it. The novel dispersant with low PDI reduced viscosity most when compared with the traditionally fractionated polymer dispersants. Results indicated that even higher solids concentrations can be used at the same amount of dispersant when the novel low PDI polymer dispersant is used. Alternatively, lower dosage of novel low PDI dispersant can be used compared to traditionally fractionated dispersants.

Sep 1, 2012

By B. P. Baruah

A good deposit of high sulphur coals of tertiary origin is existent in North eastern region of India. These coals are known to have indifferent characteristics in comparison to other Indian coals. The general Physico-chemical characteristics are low ash and high volatile matter, calorific value and sulphur content. Sulphur in these coals (70-95% of organic) is mostly affixed to the structure of the coal. Owing to the stringent environmental regulations, the utilization of these coals has severe limitations due to high sulphur content. In the present investigation, sulphur incorporation in to these coals has been discussed along with possible organic sulphur functionalities. The various desulphurization techniques carried out for removing sulphur from these coals have been discussed. Two step oxidative desulphurization processes has been found to be most efficient for organic sulphur removal along with mineral matter and potential toxic elements. Keywords: oxidative desulfurization, potential toxic elements, sulfur incorporation

Sep 1, 2012

By Graeme Lamson, Rene Dobbe, Merle Kalstrom, Janice Baron, Robert Thorpe, Chris Martin, Snezana Bajic, Amanda Palko

"This paper presents early results from a case study at the Mount Polley porphyry copper mine in British Columbia, Canada. Daily mineralogical data was acquired and reconciled with daily plant assay and recovery balances to interrogate the mineralogical controls on plant performance. After commissioning, the Minesite machine operated smoothly and reliably, creating daily data to generate mineralogical balances around the circuit for a period of several weeks. The key data, on final products were produced within 13 hours of the end of the respective operating period. The resulting information allowed for a greater understanding of the opportunities and limitations of the Mount Polley metallurgy. In this paper, how this information can be used to help long term strategic planning for the operation, as well as mine planning and production forecasting and the fine tuning of day to day mill operations is described. Early data available at the time of preparing this paper indicated that roughly 40% of the sulphide losses, or 32% of total copper losses existed as low grade inclusions in +75 micron tails. This represented the dominant form of long term copper losses, demonstrated repeatedly in the routine analytical data. However, on a day-to-day basis, the amount of copper present as chrysocolla is the major driver behind variations in total copper recovery. The degree to which this influences mill recovery is valuable to the geologist or mine planner. As they are armed with mineral speciation information for future ores, this will allow for improved mine planning, prediction of copper recoveries and production forecasting. The data was also started to find value in the mill by showing what caused sulphide losses. In the roughers, for example, the data showed poor recovery was the result of poor flotation performance and not any changes the speciation of copper sulphides or their liberation characteristics."

Jan 1, 2014

By József Faitli, Barnabás Csoke, Károly Solymár, Zoltán Hatvani, Dimitri Papanastassiou

"Grinding has a significant economic impact on ore dressing/processing, therefore the sizing of mills has an outstanding role.In most cases, the sizing of dry or wet mills for ore processing is primarily based on the determination of the Bond grindability index, using the Bond-Kjos-Rowland relations. In several cases, grinding takes place under conditions different from these and the grinding conditions have a great influence on the post-grinding process. This is particularly true for the grinding of bauxites where grinding takes place in alkali, often in higher temperature (up to 100 ºC) in alkali Liquor. So it is necessary to develop a testing method providing a reliable grindability index even under these special circumstances (grinding in alkalis medium at different temperatures) and allowing a more precise mill sizing. The new heated mill is suitable to determine the grindability index under temperature-controlled circumstances, in liquids with different temperatures (water, alkali). This paper presents in detail the equipment, the conditions (parameters) of the testing process for wet and alkaline grinding, the measuring results and the conclusions."

Jan 1, 2003

By J. M. Ortiz, J. Haas, W. Kracht, G. Pamparana

This work explores the effect of ore hardness variability on the design of a solar photovoltaic system with battery storage and grid backup, to operate a semi-autogenous grinding mill (SAG). First, a case of two synthetic ore populations was studied, without any consideration of spatial distribution. The mean and variance of the ore hardness (measured in specific energy consumption, SEC) of both populations were subjected to a sensitivity analysis. The operation was evaluated with one and two stockpiles. The latter allows classifying according to ore hardness as a way to adapt the SAG energy consumption to the solar cycle. The results show that using two stockpiles allows achieving a larger autonomy (i.e. less energy imports) at lower total costs, especially when the difference of mean hardness between the two populations is large. The difference in variance (between the two populations) has a smaller impact on the design recommendations. Second, a case study was performed considering the spatial distribution of geometallurgical units. Two cases were considered: (a) brownfield, when there is historical information of the actual variability of the ore hardness; and (b) greenfield, when the system design relies mainly on geometallurgical modeling. Brownfield and greenfield planning result in similar sizing recommendations of the solar power plant, if precise drill cores are available. In this case, geometallurgical modeling is an effective tool for forecasting the energy demand necessary for designing the power plant.

Jan 1, 2018

By Bent Babel, Martin Rudolph

"The characterization of reagent-mineral interactions in flotation systems of finely intergrown ores holds difficult challenges for the applicability of standard techniques like Hallimond tube tests and contact angle experiments or renders them impossible due to a lack of sufficient samples in terms of quality and quantity. This disadvantage may not apply to more sophisticated techniques, but these often do not work in an aqueous environment. We present the utilization of an atomic force microscope with a hydrophobic colloidal probe to characterize the wettabilities of individual mineral domains of an ore sample, while additional spectral information is gathered by Raman spectroscopy. The exemplary ore sample investigated is mainly containing cassiterite and quartz, therefore the reference measurements like Hallimond tube tests and contact angle experiments were carried out with this binary system as a comparison. The focus of the study lies in the correlation of data gathered by the atomic force microscope and the Raman spectrometer with data from standard techniques. Finally, the applicability of the colloidal probe atomic force microcopy technique for reagent-mineral investigations is critically evaluated.INTRODUCTIONThe focus of this paper is the application of colloidal probe atomic force microscopy (CP-AFM) for theinvestigation of reagent-mineral interactions on a binary system of cassiterite and quartz. This and similar concepts using hydrophobic AFM probes have been applied by multiple authors (Rudolph and Peuker, 2014a; Rudolph and Peuker, 2014b; Wada et al., 2017; Xie et al., 2017). The hydrophobic interaction is the main interacting mechanism for the hydrophobic colloidal probe with hydrophobic sample surfaces and the long range attractive component has been accounted to nanobubbles on the interacting surfaces (Yakubov et al., 2000). More detailed information on nanobubbles are available in two reviews compiled by Attard and Hampton (Attard, 2003; Hampton and Nguyen, 2010). This paper is based on the work by Rudolph and Peuker comparing different AFM based measuring concepts, additionally gathering data with Raman spectroscopy and correlating results of microflotation and CPAFM measurements (Rudolph and Peuker, 2014a; Rudolph and Peuker, 2014b)."

Jan 1, 2018

By Masanori Mori, Hajime Miki, Osamu Ichikawa, Tsuyoshi Hirajima, Mitsuru Sawada, Keiko Sasaki

For pretreatment of selective flotation, surface oxidation of chalcopyrite and molybdenite was applied by oxygen plasma then the minerals were washed by solution at pH 9 with oxygen bubbling. Surface characteristics of these minerals were investigated with AFM, XPS, zeta potential and contact angle measurements. Contact angle of chalcopyrite and molybdenite decreased a lot by plasma treatment. When they were washed with pH 9 solution with oxygen bubbling, contact angle of molybdenite increased whereas chalcopyrite one kept low. Adhesion force measurements indicated similar behavior. Result of flotation experiments indicated low recovery of both chalcopyrite and molybdenite after plasma treatment and only molybdenite recovery became higher after washing. Selective flotation of chalcopyrite and molybdenite could be achieved with this process. Possible mechanism of selective flotation was proposed from the results of XPS, AFM, etc.

Jan 1, 2014

By I. Gombköto

In the EU-region, the automatically operated approximately 200 (rotating hammer) shredder plants processing large technical equipment (end-of-life vehicles, large household appliances) annually produces 8-9 million tons of non-metallic grinded by-product, which ends in landfills, without recovery. Although this by-product is organic material, still contains large amount of metal components worth recycling. These operations, such as shredding and processing end of life vehicles or mixed metal components are a growing market and it is become more potential if EU directive 2002/96/EC will become obligatory for new member and candidate countries and they have to apply EU regulations. Eddy current separators (ECS) are one of the most important units of separation of non-ferrous metals from insulators in waste recycling. The product of ECS processing of shredded ELV?s is usually a mixture of Al, Cu, Brass and stainless steel. This mixture has relatively low price on the market, while purified metal products are required by smelters for which shredder operators are able to get even higher price. Our aim at University of Miskolc was to find solution producing pure metal products using dry separation processes. Authors are presenting a possible solution, using ECS. Institute of Raw Material Preparation and Environmental Processing possesses an ECS, equipped with 305 mm wide belt, and a concentric magnetic rotor. The subject of our work was to investigate the behaviour of model particles with different shape, conductivity (aluminium and brass), orientation and size in order to separate Al and Brass. We used model particles with similar shapes of shredder plant originated ones. The magnetic flux and magnetic frequency was constant and derived by the design of the rotor. During our research work, belt speed and rotor speed of ECS were varied. The particle distance and trajectory caused by throwing was determined and the results are reported in this paper.

Sep 1, 2012

By Markus A. Reuter, Bernardete Castro, Antoinette van Schaik, Han Remmerswaal

This paper describes the inseparable relation between product design, liberation, and metallurgical recovery in the optimisation of the recycling of passenger vehicles. This is illustrated by the use of an optimisation model that uses among others a material combination matrix based on metallurgical process data, which depicts the consequences of the quality of intermediate recycling products on the metallurgical material recovery and final alloy metal quality. Various simulations will illustrate the effect of changes in product design and hence liberation on the recycling of end-of-life vehicles. Although this paper focuses on cars, the discussion is equally valid for any end-of-life product. Calibration of the model will be discussed with reference to experiments carried out in order to study the optimal recovery of aluminium applications used in passenger vehicles.

Jan 1, 2003

By V. V. Morozov, I. S. Barmin, A. V. Tugolukov, V. V. Polivanskaya

"It was presents the results of research on improving reagent regime and scheme of enrichment of slime classes of Apatite-Staffelite ores and tailings stockpile of Kovdorsky enrichment plant. It was investigated the regularities of flocculation in the processes of thickening and selective flotation apatite-bearing ores. It was established character of the influence of flotation reagents on the flocculation process. It was shown that the sodium silicate and soda ash have a stabilizing effect by thickening of sludges. Neonol and oleic acid have a coagulating or flocculating effect. It was tested the new regime flotation, involving an initial conditioning with using of reagent - dispersants before feeding the pulp into the flotation and subsequent conditioning with reagents having a coagulating effect. The flowsheet and reagent regime for enrichment of fine-grained tailings stockpiled was developed, which providing production of standard apatite concentrate and increasing the recovery of valuable components. There are presented results of the research of activities of strong organic surfactant on solubility of colloidal form fatty acid collector and aggregate stability of fine minerals in the process of thickening and flotation. Surfactants such as Neonol have been investigated for increasing the activity of the collectors. When using the process of thickening sludge fraction with flocculant Praestol 2540 and stadial conditioning of sludge were obtained concentrates containing up to 38.1% P2O5 at recovery. INTRODUCTION A feature of the Apatite-Staffelite ores of the Kovdorsky deposit is the presence of a large number of fine mineral particles and a reduced hardness of phosphate minerals (Beloborodov et al., 2010, Tugolukov et al., 2012). Formed in the ore-preparation process, sludges are lost with a discharge in the thickening operation. Sludge is characterized by an increased content of phosphorus pentoxide (P2O5). Losses of P2O5 at enrichment of the stale tailings of Kovdorsky GOK reach 14.0%. The high losses of P2O5 caused a profound study of the behavior of thin apatite classes under conditions of thickening and flotation."

Jan 1, 2018