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By A. F. Usov

A potential of electric pulse disintegration in benification used for primary deposits ores containing precious metals is shown. Of special significance is that PGM and gold grains, being highly plastic, are easily liberated and are not smeared on the disintegrated rock fragments surface. It al-lows gravity separation, which is less expensive and more efficient, to be used instead of chemical processing, which is expensive and environmentally faulty.

Jan 1, 2014

By Güven Önal, Gülay Bulut, Mustafa Özer, Yunus Emre Benkli, Olgaç Kangal, Mustafa Tarkan

There are various types of natural zeolite deposits in Turkey. Naturally occurring zeolites are excluded from many important commercial applications where uniformity and purity are essential. In this paper, the beneficiation of natural zeolite, taken from western part of Turkey, was investigated. According to X-Ray Diffraction (XRD) and mineralogical studies carried out on the representative ore sample, the natural zeolite was found to be in the forms of clinoptilolite and heulandite. Clinoptilolite forms as a devitrification product of volcanic glass in tuffs. Quartz, clay minerals, orthoclase, plagioclase, biotite, seruzite-muskovite and epidote were observed as impurities. Several types of mineral processing methods were performed in order to remove impurities from the natural zeolite sample to produce high purity zeolite. Gravity separation methods such as shaking table and superpanner were carried out for separating heavy minerals, while high intensity dry magnetic separation was used for discarding magnetic minerals.

Jan 1, 2003

By S. P. Das

Tumbling mill is an important unit operation in a mineral processing industry whose operation needs to be understood to make it an energy efficient unit. One of the important mill parameters is the impact spectra generated by collision of the moving charge mass on the mill shell. This process also generates mechanical vibration on the mill shell and propagates to the plumber block of the mill. In this work, we tried to understand the impact spectra by using different minerals such as Banded Hematite Quartzite (BHQ), Hematite and Quartz as mill feed of a semi-autogenous (SAG) mill. The said mill is of 1000 mm diameter and fitted with a force sensor on the mill shell and a vibration sensor on the plumber block. The analysis of the impact spectra was done by taking into consideration the peak impact force above a certain threshold value. It clearly shows that the impact force decreases as the particle size become finer irrespective of the mill feed material. This can be used as an effective tool by the mill operators to have an understanding of the mill product size reduction. The mechanical vibration tapped by a tri-axial accelerometer was analyzed by power spectral density analysis. The vibration signal analysis shows the variation in the power spectrum magnitude both at lower and higher frequency. It also shows inconsistency in case of BHQ where it shows a significant decrease in vibration at lower frequency and increase in vibration at higher frequency. Therefore, the impact spectra analysis is a better method compared to vibration analysis in understanding the mill product size reduction.

Sep 1, 2012

By Heribert F. Broicher, Arne Volland

The application of remote sensing techniques combined with fluorescence spectroscopy is realised in analytical devices called LIF Analysers. The analysis of laser-induced fluorescence facilitates non-destructive, non-contact, on-line and real-time rock identification and quality control of bulk solids in transport. LKAB of Sweden was the first company to test LIF Analysers in the Kiruna Mine for bulk sorting of run-of-mine ores depending on the phosphorus content. Other applications tested in Germany so far are quality control of limestone (iron and/or dolomite content) and rock identification in lignite mining. Of special interest also is rock identification in diamond mines for dilution control. The paper summarises the present state of the application of LIF Analysers.

Jan 1, 2003

By Antoineta Boteva

A significant part of the currently production of the non-ferrous and precious metals is from sulfide ores. Character feature of sulfide ores is the presence in them always pyrite and wide range of different sulfide minerals else. These minerals are the carriers of valuable for industry metals. Due to the low content of the main components, very often call on the use of collective- selective flow-sheets. The extraction of minerals in the collective concentrates determined in a large extent the effectiveness of the collective-selective sheets. In conditions of bulk flotation kinetics to floatate of the various minerals is different. Due to why it is and how it can be used for a more effective selection of minerals ?this is the main task of this report. For this purpose are used results from the bulk flotation of pyrite, copper sulfides, molybdenite, galena, blenda. It is separated and place of host rocks. Base it of large experimentation material, including both electro-kinetic measurements of mineral systems, as well as laboratory flotation tests and factories monitoring it is established kinetics of flotation of mineral particles in conditions of collective flotation. Made an effort to clarify the effect as of the species and the proportion of different sulfide minerals involved in flotation pulp else. Traced was the impact of the density and aeration of the flotation pulp on deferens in kinetics of mineral flotation in condition of balk flotation. The obtained results are used to increase the efficiency of the diffraction flotation of the complex sulfide ores containing precious metals. In the schemes, it is possible precious metals to fall in the most appropriate for the next processing products. Keywords: flotation, sulphide ores, kinetic extraction

Sep 1, 2012

By Wenying Liu, Marek Pawlik

Long-chain ionic surfactants, with fatty acids and amines as the most important representatives, are widely used as collectors in froth flotation. These surfactants, generally referred to as weak electrolyte collectors, frequently form solid insoluble precipitates within a certain pH range. However, the action and behavior of these colloidal precipitates in froth flotation systems are not well understood and has not been well decoupled from those of dissolved forms. The objective of this study was to understand and compare the role of colloidal precipitates with that of the dissolved forms at gas-liquid and gas-liquid-solid interfaces. Using primary amine as the model surfactant, experiments were carried out to measure: the maximum volume of bubbles generated in the presence of dissolved and precipitated forms of the surfactant; surface tension for both forms of the surfactant using the drop shape and maximum bubble pressure methods; and contact angle using the sessile drop method. The experimental results showed that: in the presence of the precipitate, bubble volume was smaller, which was correlated with the lower surface tension and higher contact angle measured; the surface tension of solutions containing surfactant precipitate was affected by the surface age of liquid droplets. This study enhances understanding of the interfacial behavior of long-chain ionic surfactants under different conditions, which would help improve the efficiency of reagent utilization in froth flotation.

Jan 1, 2014

By A. Oberrauner

Electrostatic separation is a dry separation technique usable for many applications in the mining- and recycling industries. At the Chair of Mineral Processing intensified research has been done on this topic during the last years. One challenge was to measure the triboelectric charging of fine mineral particles in a triboelectric charging device consisting of an electrically insulated polyethylene rotor/stator assembly. These tests, performed on monomineralic samples, were accomplished in a climate chamber. It was shown that charging of minerals not only depends on rotor speed, feed rate and atmospheric circumstances but also on the properties of the applied electrostatic field. Tests on pure calcite in contact with the polyethylene rotor/stator system resulted in specific triboelectric charges up to +10 nC/g at low relative humidity. With more water present in the surrounding atmosphere, these charging values decreased significantly. However, at higher relative humidity, triboelectric charge values could be maintained after an electrostatic field of positive polarity was applied. Similarly, charging behavior was found with other hydrophilic minerals. The idea behind all these tests was to find the largest charging difference between minerals occurring together in a deposit and to be able to charge them oppositely, assuming that this means good sort ability in an electrostatic separator. The results gained from these investigations are shown. After having obtained many results on charging pure minerals, it became interesting to test the applicability of the charging tendencies on electrostatic separation of fines <100 µm. In order to do so, a separator for fine polymineralic powders was developed, constructed and combined with the triboelectric charging device, all being set up in a climate chamber. This new so-called coax-separator is presented along with first test-results.

Sep 1, 2012

By Xiaodong Jia, Richard A. Williams

"The packing of particles is a fundamental property of a material or system made up of particulates because it underlies many other physical properties of that material or system. Despite being ubiquitous, particle packing has not been an easy subject to study either experimentally or theoretically, except for a few regular shapes.This paper describes the recent developments, arising from research at Leeds, in the computer modelling of packing of complex shaped particles and prediction of physical properties of the structures represented by the packing. The computer model DigiPac, is capable of packing particles of any shapes and sizes in a container of arbitrary geometry. Figure 1 shows a few examples that are relevant to the mining and mineral industry.The ability to predict packing structure of real particle shapes and to compute directly some structuredependent physical properties (such as liquid permeability, mechanical strength/stability, compaction and sintering, dissolution and leaching, etc.) is obviously highly desirable and has significant potential in industrial applications. Examples are presented relating to the packing of granular materials.The mining and mineral engineering industries are well placed to exploit this advance in digital packing and simulation since they deal primarily with asymmetric and complex particulate mixtures. In the future we expect to see a number of developments in this area including:Algorithms that can optimise packing to achieve user-defined propertiesA more rational approach to determining flowability of complex powdersUse of these more realistic packing algorithms linked to blast and crusher design"

Jan 1, 2003

By Reuter M. A., R. D. van der Weijden, W. F. C. van Wageningen

"Copper(II) can be recovered or removed from acidic copper sulfate solutions as cuprite or metallic copper powder by reduction with carbohydrates. The copper powder characteristics, such as size and shape of particles, determine the tendency to adhere to reactor walls and to agglomerate. In order to make this process suitable for a commercial scale pipe reactor, process conditions and the reactor configuration were varied in order to influence the copper characteristics in a positive way. The aim was to achieve proper particle throughput in the pipe reactor and to obtain a well defined copper powder.In this paper the effect of both, chemical and physical parameters on the shape and size of particles were systematically studied in a number of autoclave experiments. These parameters include mixing, Cu(II) concentration, pH, temperature, seeding, use of additives and reactor materials. Additionally, Monte Carlo simulations of copper growth inside a Kenics static mixer were made. Results show that the use of additives and the use of static mixers influence particle characteristics the most."

Jan 1, 2003

By G. N. Jadhav

In India, bauxite deposits are concentrated in Central India, Western Ghats and Eastern Ghats. Bauxites from various regions in Gujarat were identified during the present investigations of geochemical mapping. Different types of Bauxites samples were collected from Kachchh, Jamnagar, Porbunder, Junagarh, Bhavnagar and Amreli areas of Gujarat state and were studied in detail for their geochemical signatures to plot the data on Geochemical map. Raw bauxites were characterized by using powder XRD, XRF, ICP and optical microscopy techniques (with the help of Model microscope having both transmitted and reflected light setups) and were later examined to grade their quality. Most of the bauxites from Kachchh region were of high-grade (gibbsitic) type; while those of Sourashtra region were of low-grade (lateritic / calcitic) types. Most of these bauxites were either of ferruginous/lateritic or of calcareous/calcitic types. Based on the mineralogical composition, such as gibbsite, hematite and/or goethite, Kaolinite and calcite minerals present in particular bauxites, the deposits were graded. Finally, the Geochemical mapping of Bauxites for Gujarat region was prepared and discussed.

Sep 1, 2012

By A. N. Zagorodnyaya, T. N. Bukurov, Z. S. Abisheva, A. S. Sharipova

"The paper describes the results of stripping of copper production dusts by leaching with aqueous soda, nitric acid solutions and recovery from solutions resulting in the production of lead sulphate, tribasic lead sulfate (TBLS), ammonium perrhenate, zinc, copper-cadmium cake.The combination of two stripping operations under chosen optimal conditions allows the recovery of 98% rhenium, 82% lead, 92 % copper, and 96% zinc and cadmium each. The major amount of rhenium (~ 80%) is recovered at the carbonization stage, and other metals - at the nitric acid leaching stage.Lead sulfate was precipitated by mixing solutions resulting from carbonization and leaching. Tribasic lead sulfate was produced by dissolving lead sulfate in sodium hydroxide solutions. Rhenium was recovered from mother liquor resulting from lead sulfate precipitation by liquid-liquid extraction and zinc was recovered from raffinates. Trialkylamine (TAA) was used as an extractant for rhenium recovery and di-2- ethylhexylphosphoric acid was used for zinc recovery. Optimal liquid-liquid extraction parameters have been defined allowing the recovery of 96% rhenium in crude ammonium perrhenate and 94% zinc in sulfuric acid solution. Based on the experimental data, the flowchart for dust processing to produce salable products - lead, rhenium, zinc salts has been suggested."

Jan 1, 2003

By Stephen J. Harker, John Knights, Randolph A. Pax, Glen A. Stewart

"Mineral samples were obtained from different stages of a mineral processing circuit used to extract the copper and gold rich mineralogical phases. The aim of this work is to characterise the quality of the samples at different stages of processing. The samples were taken of the head grade, tailings, cyclone overflow and the final concentrate.Characterisation of the samples was determined using Cu-Ka X-ray powder diffraction and Fe57 Mossbauer spectroscopy. These measurements will be presented and discussed in terms of the enrichment of the ore, showing the removal of magnetite and quartz through the processing, the final concentrate being rich in chalcopyrite and pyrite. This data also shows the utility of Mossbauer spectroscopy to provide mineralogical phase information directly.Mossbauer spectroscopy is a tool to determine the material phases of a sample. It is a nuclear based technique which measures the amount of attenuation of a narrow Doppler shifted source energy as it passes through a sample. The attenuation depends on the amount of resonantly absorbing material in the nuclear radiation path from the source to the detector. Synchronous detection of the doppler shifting velocity and the nuclear radiation count gives a Mossbauer spectrum. By convention, the energy axis of the Mossbauer spectrum is displayed in units of velocity.Figure 1 shows Mossbauer spectra obtained for a sequence of samples throughout a processing plant. These spectra show the removal of magnetite and the concentration of chalcopyrite and pyrite. Optical microscopy results indicated a significant component of bornite not witnessed with Mossbauer spectroscopy. Closer examination showed that optical microscopy assays over estimate the bornite component."

Jan 1, 2003

By G. S. Hansford, G. E. Searby

The rate of bioleaching of pyrite at 70ºC by a thermophilic archaeal culture was measured as a function of the solution redox potential by the staged addition of pyrite to a batch system. The results were compared to the rate of ferrous iron oxidation over the same potential range to determine the applicability of the multi-sub-process leaching mechanism developed for mesophilic bioleach systems.

Jan 1, 2003

By D. Gucbilmez

Three spiral concentrators having different geometries were compared in a chromite processing plant. They had different diameters, helix-cross sections and capacities. Two of the spiral concentrators were manufactured in China and one of them was manufactured in Australia. The tests were carried out in a closed circuit experimental setup by using a low grade chromite ore. The pulp densities kept the same during the operation, and the samples were taken simultaneously. The effects of the different positions of the splitters on separation and the feed rate were the parameters that were observed during the experiments. The performances of three spiral concentrators were found to be different. To clarify the effect of the particle size on the separation in spiral concentrators, the screening was applied to the feed. The samples were sieved from 75µm. The test results indicated that the separation performance decreased dramatically in very fine particles. Although fine particles caused some problems in spiral concentrators, fine grinding is required for this particular chromite ore for better liberation. A suitable method for the fine particles should be investigated for acceptable recovery.

Sep 1, 2012

By Sebastian Fredes, Williams Calderon, Mauricio Toledo, Gonzalo Montes-Atenas

The influence of the temperature on leaching kinetics of copper-bearing minerals has been widely acknowledged: the leaching of copper oxide ores is generally described as exothermic reactions while copper sulfide ores are associated with endothermic reactions. Reports studying the influence of temperature on leaching kinetics at laboratory scale frequently involve the implementation of either fully flooded isothermal systems or jacketed column setups. Nevertheless, at industrial scale controlling or monitoring the temperature or temperature changes is almost impractical. In fact, leaching process is usually a large tonnage operation and changing the temperature of vast amounts of material would require an enormous amount of energy and highly specific heat transfer equipment. Preliminary computations on the amount of energy required to increase the temperature of a heap or dump in 1°C indicates that it would be impossible to find an energy source able to accomplish the task. In order to provide a solution to this matter it is suggested to create an energy managing protocol (EMP) that permits heat up or down the porous body locally taking advantage from the temperature gradients and from the reactivity of different regions within the material as a function of the leaching cycles. The aim of this study is to evaluate different heat transfer regimes in a 1 ton pilot column leach operation. It was found that best results of copper recovery are obtained when heating up the column in horizontal bands starting from the top of the column moving downwards as the leach cycle evolves. The system is expected to be suitable for industrial applications, but further development of the technique is required, particularly in the design of the heat transfer dispositive.

Jan 1, 2014

By H. Lieberwirth, M. Hesse

"Selective comminution (SC) is beneficial for the treatment of primary raw materials, especially if it is utilized in the pre-concentration process. Pre-concentration processes are applied in mineral processing to relieve subsequent processes and to achieve a higher efficiency. SC is also a promising method for the treatment of low-grade ores and waste dumps. With SC, various components can be separated such as valuable minerals from waste, ore from wall rock and different ore varieties within a deposit. SC is a property of a comminution system and leads either to a preferred crack propagation in one component (called preferential breakage) or to a preferred crack propagation along the grain boundaries (called interfacial breakage). SC results from different comminution behavior of various components in the feed material. For mechanical comminution, the preferential breakage seems to be the most important case of SC. Hereby SC generates only the difference in the particle size which can finally be used as a sorting parameter. A sorting process which uses SC depends on three parts: the feed material, the comminution machine and the separation machine. The feed material defines the potential for SC. Differences in properties like strength, toughness and density which are related to comminution are often used. The comminution machine has to exploit this potential. The extent of the exploitation can be influenced by the machine design, material and operational parameters. After SC, the various components are still combined in the product. So ultimately, a separation machine is needed. At preferential breakage, a simple screening machine can be used. The basics about SC will be presented at first. This contains relationships between material properties, the kind of loading in the comminution machine and the SC effect. These basics can be used for example to exploit a potential to SC for a pre-concentration step or to avoid the SC for a higher efficiency of subsequent processes. Based on recent investigations with impact load, the influence of the important parameters compressive strength, density, particle size and impact velocity to the SC will be shown, using examples of lead-zinc ore comminution and fluorspar processing."

Jan 1, 2018

By Christopher M. Rule, Martyn P. Hay

"A methodology was developed in the mid-1980’s to predict plant performance from standard laboratory flotation tests. The methodology incorporates a flotation simulation program “SUPASIM” which translates flotation performance from bench-scale tests to full-scale plant. The technique is based on a simple, empirical kinetics model, and is tailored for use by the practical metallurgist. Kelsall’s unmodified equation incorporating two rate terms describing slow and fast floating components is used as the basis of the method. The flotation behaviour of an ore is described by a set of numbers, which can be compared in the evaluation of ore types, mineralogy and operating conditions. In so doing a precise relationship is developed between metallurgical performance in terms of grade and recovery and flotation kinetics.To date the performance of more than 20 flotation plants has been predicted, encompassing copper, lead, zinc, nickel, phosphate, pyrite, graphite, cassiterite, platinum and various slags. In three cases, plants have treated more than one type of ore. The method has successfully been used to predict and design four flotation plants using data generated from bench-scale laboratory flotation testwork. All have since been commissioned, and have performed as predicted. In the last year alone it has been used to drive flowsheet development for at least seven new plants in South Africa and the Americas. It is also being used to assist in the optimisation of existing operating plants."

Jan 1, 2003

By Gabriel C. Aguilera, Juan Arismendy

"The effect of rheological factors inside of a hydrocyclone is very relevant for the fluid mechanics and for the classification of materials on suspension, since parameters such viscosity and thixotropy are intrinsic variables that depend of the particulate system and the continuous phase; they determine the efficiency of classification. Nevertheless, the exact knowledge of the main characteristics and magnitudes of them inside the hydrocyclone is very difficult because of the geometry of the hydrocyclone, even more if the hydrocyclone is of small diameter. Hence is not possible to make a hydrodynamic study with effects over classification regarding these variables. This work studies the rheological variables inside a small diameter hydrocyclone that works at high pressures, using the information given by a model of Computational Fluid Dynamics (CFD). The model used includes the Reynolds Stress Model (RSM) for the evaluation of turbulence, and the Volume of Fluid (VOF) to study the interaction between water and air, which is very important to obtain regarding the effect of the air core over the performance of the equipment. The validation of the CFD model was done with a kaolin suspension at several conditions of solids contents below the critical volume fraction, without chemical additive aid. These conditions are representative of current work parameters on plant. As result it could be established the ranges of evaluation of rheological variables on specific regions inside the hydrocyclone, and through a rheometric study, based on the mechanic characteristics previously obtained, the main rheological characteristics of the mineral suspensions were determined."

Jan 1, 2014

By Victor Avdokhin, Valery Morozov, Valery Stolyarov

"The adaptation-determination method provides for keeping given relationship between concentrations of ionic and molecular components of a pulp liquid and correction of parameter of the model on the basis of analysis of ore composition, technological parameters of flotation, and cost of valuable components.• optimisation program “ADDEFLOT” and combined analyzer of pulp “RA-931”An adaptation-determination method provides for two-level control of bulk and selective flotation of polymetallic ores. The lower level provides for control of reagent dosing on the base of control of ionic composition parameters in the pulp liquid phase. The control goal is to keep the basis relationship among parameters of ionic composition (ions A, B, C) in pulp liquid phase given by equations of type:• alg[A] + blg[B] + clg[C] = K (1)Values of a,b,c coefficients are uniquely determined by a physico-chemical model used. Kind of the model depends on mineral composition of an ore and reagent regime applied. As parameter of ionic composition, also values of one or two parameters (or their combinations) can be used, for instance, pH, concentration of sulfide ions, ions of collector.The upper level of control is based on calculation and use of technological results of selective flotation. At the level, an adaptation of the model (1) is conducted. A principle of the adaptation is in determining (and including in pre-setting function of the lower level) such value of K parameter, at which maximal economic effectiveness of the process is reached. As a criterion of economic effectiveness of the process, a function of losses of several valuable components, taking into account cost of the metals lost, is used. For 2-component ore, in simplified form, the function is as follows:"

Jan 1, 2003

By Garren Edwards, van der Westhuizen. Andre

"Due to the depletion of easily treated coarser ores, more mineralogically complex ores with smaller valuable mineral grain sizes are treated, the means to liberate these minerals lies in grinding finer (Partyka & Yan, 2007). Grinding to these fine sizes is energy intensive, and using standard ball mills are energy inefficient at these sizes (P80 < 75µm). Therefore, stirred mills are becoming increasingly prevalent in the mineral processing industry. In order to optimize these mills, the effects and mechanisms of the significant variables need to be understood. This paper investigates a laboratory scale vertical stirred mill (Deswik mill) in an ultra fine grinding application of a South African platinum ore. The operating variables that are considered are stirrer speed, media size, media filling, and slurry density. The resulting grinding efficiencies are considered in two ways. Firstly, a statistical model is fitted to identify the effect of the significant variables on grinding efficiency, and secondly, the grinding efficiencies are also considered in terms of a stress energy model to determine whether this can partly explain the grinding mechanism in this mill. A factorial design of experiments was used on three levels for each variable, such that only linear interactions, second order interactions and two variable interactions are included in the statistical model. The results show that tip speed, media size, percent solids and mill filling are all significant to the grind, at differing energy inputs in the grinding process. The interaction effects of these variables are also dependent on the energy inputs. The results also found that the Kwade stress energy model is applicable to this mill and can be very useful to find the most efficient operating conditions for this system. The most energy efficient operating conditions in terms of mill speed and media size were typically somewhat below the standard operating conditions and it is expected that this is most probably done in order to increase the grinding rate, but at the expense of sacrificing some grinding efficiency."

Jan 1, 2014