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By O. Guven, I. Karaagaçlioglu, O. Ozdemir, M. Çelik

In this study, the effect of morphological properties such as shape factors and roughness of the glass beads on their flotation efficiency were determined using image analysis and profilometer methods. There is a considerable correlation between the shape factors, surface roughness and flotation behavior of the glass sample. These results indicate that as the particle shape is away from roundness and smoothness, it acquires more hydrophobicity.

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 Olgac Kangal, Ali Guney, Gulay Bulut, Guven Onal, Ayhan A. Sirkeci

This paper presents the results of pilot scale column flotation applications in the two different copper concentrators in Turkey. The Kure Copper Plant is located in the Black Sea Region of Turkey. In Kure, a very fine grinding requirement for an adequate level of liberation makes a successful flotation difficult and consequently the final concentrate can hardly assay above 16% Cu Column flotation tests were conducted at the plant site using two different column types The experiments proved that the grade of the concentrate could be increased from about 14% Cu to 25-26% Cu. Murgul Cakmakkaya Copper Concentrator is the largest copper concentrator in Turkey. Although concentrate production capacity is around 170,000 tons annually with 22-23% Cu content, this figure tends to be much lower than that. In Murgul a Turbo Column of Multotec Company of South Africa was employed. As a result of systematic column flotation tests, the grade of the concentrate was increased from 20.3% Cu to 28.7% Cu.

Jan 1, 2003

By H. C. E. Regidor, M. G. Mena, H. D. Mendoza

Cyanidation leaching has always been the most widely used method of extraction of gold in the world. Its low cost and high selectivity has made it the prevalent choice for mining companies, and even for the small scale miners. The use of cyanidation in small scale mining has been an issue for the longest time, mainly due to the operation’s lack of safety measures, health care or environmental protection regulations. In pursuit of more environmentally friendly methods of extraction of gold, several alternative extraction processes have been explored, one of which is chlorination. The chlorination process is advantageous when recovering refractory gold locked in sulfides, as it simultaneously oxidizes the surrounding sulfides as well as dissolve any gold exposed to the lixiviant. This research was conducted to study and develop a safer alternative way of extraction of gold from small scale mining operations, without compromising the recovery of gold. In this study, a variation of the chlorination process has been employed for a refractory flotation concentrate wherein the majority of the gold is locked in sulfides. Hypochlorite-bearing reagents were used as the leaching reagents, and the method developed was a 2-stage leaching process in differing pH conditions. The solution pH and Eh was monitored all throughout the runs, and aliquot samples were taken at time intervals for analysis. SEM-EDS imaging was used to determine the mode of oxidation of the chlorination process, and the image obtained showed that the oxidized layer followed the shape of the particle, suggesting a diffusion controlled process. XRD analysis of the sample before and halfway through leaching further confirmed the oxidation of the sulfides. The amount of gold dissolved in the aqueous solution and in the solid residue were used as the basis for the determination of the recovery of gold. An average gold recovery of up to 84.38% was obtained using the developed method in just 7 hours of leaching. This method was then employed for a pilot-plant scale test and a gold recovery of 79.2% was obtained.

Jan 1, 2018

By G. Weingrill, H. Flachberger, J. Neubacher

The so called Bublon®-process is an innovative process for the controlled expansion of volcanic glasses such as Perlite and for thermal treatment of other minerals. In this manner, functional light fillers with astonishingly altered physical properties can be manufactured. In contrast to conventional Perlite expanding processes no fossil fuels are burned in order to achieve the expansion. Instead, the feed material is heated electrically mainly by radiation based on heat transfer from heating elements. The main advantage is the better controllability of the production process. Therefore, the heating elements are segmented along the flow of the particles, hence in direction of the ongoing expansion. Overheating of the particles, which ultimately leads to the destruction of the particle surfaces and consequently decreasing the quality of the expansion product, can be reduced significantly. Due to flow characteristics and settling behaviors of fines the lower particle size limit of the feed in this process is restricted to not less than 100 µm. Otherwise process instabilities are to be expected. Manufacturing industry demands light and fine hollow microspheres. Therefore, a proven cooperation between Montanuniversität Leoben and Bublon GmbH was formed to develop a new process called ‘Bublite’. This issue was addressed by changing the conveying principle into a pneumatically conveying system transporting particles from the bottom to the top of the kiln by the means of a drag flow. This approach makes it possible to handle the difficult flow patterns in the kiln and to control the retention time of the particles in the heat transfer zone. As a result, it is now possible to expand very fine Perlite particles into a high quality functional lightweight filler with a glazed-closed surface. The dependence of the polymer industry on importing this kind of fillers from overseas can be reduced by producing it close to sites of demand. Also the Perlite mining and processing companies benefit from this technology because the mine lifespan and the output of the processing plant can be increased.

Jan 1, 2018

By Mauricio Guimarães Bergerman

At the regrind or secondary grinding stages of base metal ores, the concern about energy efficiency is usually extremely important. In general, the specific energy consumption at this stage is higher than during the primary grinding stages. In addition, a tendency of finer grinding has been observed in the new projects of metallic minerals, due to the finer mineral liberation, which leads to increasing capital and operational costs. At Vale?s new copper projects in Brazil, regrind sizes with a P80 of approximately 40 to 20 µm have been necessary. Conventional ball mills, adequate for primary grinding, usually bring about low energy efficiency with products bellow 50 µm. Vale is using the vertical mill on its copper projects ? Sossego and Salobo, in order to optimize the regrind of rougher concentrates and reduce energy consumption. This paper presents the results of industrial surveys carried out on the Vertical mill circuits of Sossego plant during its initial years of operation, and compares these results with the design criteria and laboratory regrind tests used for the mill scale up. Keywords: grinding, regrinding, copper, vertical mill, stirred mill

Sep 1, 2012

By M. E. Holuszko

This paper reports the results of induction time measurements carried out on the products of film flotation of galena and sphalerite particles from three different size fractions (38~75µm; 75~150µm; 150~212µm). As expected, the tailings (sinking fraction) from film flotation at any particular surface tension, had always longer induction times than the concentrates (floating fraction), for both minerals. The difference between the induction times of film flotation concentrate and tailings could be as little as 2.5 ms and 5 ms, and as large as 6 ms and 10 ms. These differences can be related to the different hydrophobic characteristics of these fractions, as expressed by (?c) and composition of the particular film flotation product. In addition, the induction times of the larger particle size fraction were shown to be longer than for the corresponding smaller particle size fraction, even though the average ?c(degree of hydro-phobicity) of these fractions appears to be very similar. Desliming, Cu activation and collector addition to the sphalerite samples was shown to decrease the induction time values significantly.

Jan 1, 2014

By I. I. Beloglazov, G. A. Iusupov, A. Ju. Feoktistov

"The aim of this paper is to study the numerical modeling of the crushing process in a jaw crusher with complex motion jaws using Discrete Element Method (DEM). The main goals are to ensure the conformity of numerical simulation results to the experimental data, optimize the operating modes and the crusher design and develop automated verification and calibration methodology. It is offered to use automated selection of mathematical model parameters using large- or laboratory-scale experiments instead of deriving parameters from conventional intensive material tests (e.g. drop-weight test). Experimental data were obtained from a large-scale crusher designed and manufactured by the company “Mekhanobr-Tekhnika”. Both jaws have their drive shafts located asymmetrically; one jaw is driven in the upper part, the second at the base. The crushing process involves fragmentation of single smoothed rectangular granite particles of the same weight. During the experiment, the required parameters such as particle size distribution were obtained for further computer simulations. Based on the obtained experimental data, the Rocky DEM model was built. Simulation breakage parameters were calibrated using automated parameter selection methodology based on multiple set of parameter-controlled simulations. A good correlation of the experimental data and numerical simulation data was obtained. The methodology in combination with well-known capabilities of simulation modeling will help reduce the research time in the development of new mineral processing equipment.INTRODUCTION Preparation of rock mass for enrichment includes the power-consuming processes of crushing and grinding. Initial rock mass crushing is performed by means of drilling and blasting operations. To reduce the average size of a rock piece, primary crushers, mostly jaw crushers, are further applied. The advantages of the jaw crusher are simple design, easy maintenance and repair. One of the drawbacks is large oscillating masses and, thus, high power consumption during operation (55 - 200 kW). Jaw crushing simulation will help optimize the crushing process and improve further rock transportation and processing performance."

Jan 1, 2018

By Yuliy Rubinstein

"The paper presents a analysis of the history and the trends of development of flotation apparatus. The laws of their evolution are stated and the place and role of column flotation are indicated. It is demonstrate development and different design of column apparatus. The major parameters of column cell such as diameter and height are discussed. Options are proposed on optimization of hydrodynamic characteristics of columns with large-capacity cells. High efficiency of columns with cell height of 4-6 m is shown on examples of coal preparation. A new generation of multi sectional column cells has been developed. In the cells are zones with different aerohydrodynamic parameters: combined in the machine are co-and counter- counter flows of phases. The transition from single-chamber column to multi-sectional apparatus makes it possible to create favourable hydrodynamic and aeration regimes in each section of the column dependent on the pattern of material distribution by floatability. Efficiency of application different designs column apparatus uses shown on the example of enrichment of various non-ferrous metals ores and coal. The principles of mathematical simulation of the flotation process are developed. A scaling-up procedure for column cells was based on flotation macro- and micro- dynamics simulation.INTRODUCTIONColumn flotation is considered to be one of the most significant achievement in the field of mineral processing in the end of last century. We cannot but agree with this statement but would like to understand what underlies this success. History of the flotation column can not be considered in isolation from the development of flotation apparatus on the whole. It can be argued that the first attempt to switch from oil flotation to the use of bubbles during flotation was performed Bessel brothers in 1877 (Berlin patent 42 class 22, July 2) and in 1886 (Berlin patent 39,369 May 12). According to these patents, the crushed ore was mixed with oils , hydrocarbons and water. Then the pulp received in this way was heated up to boiling . Air bubbles and steam formed during boiling facilitate the flotation of ore particles coated with oil (first patent) or bubbles been generated by the reaction of lime with acid (second patent). The evolution in the design of the flotation apparatus incorporates the following key stages. Further development is connected with the Francis Elmore’s idea to use gas bubbles received at water electrolysis (UK, 13578; 1904). This method was not introduced then, but much later, in our time and on the essentially new technical basis it found a use for sewage treatment (electroflotation). Gas bubbling under vacuum patented also by Elmore (UK, 17816; 1904) obtained a practical use. It should be noted that the method did not lose its importance till now. The design of the camera has been surely optimized (Glembotskii etal, 1963). A year later A. Macquisten (UK, 26712) developed pressure (compression) flotation. Thus, the H.Sulman, H.Picard, D. Bell’s (US, 853120, May 29, 1905) basic patent and the adjoining T. Goover’s patent 1910 (US, 953746) formed the basis of the first and most important element of modern flotation: flotation with air bubbles sucked in from the environment. In 1914, J.Callow received a patent for on an apparatus where air was sparged through the porous false bottom of the cell ( US, 1104755). Woolen fabric folded four times was fixed on a perforated metal frame to be used for air sparging (Gaudin, 1932). The following year Durrel created the prototype of the injection (ejector) apparatus. The jet aerator made it possible to significantly reduce the size of the bubbles, in comparison with the filter cloth. An apparatus with slurry pre-aeration in an airlift prior to feeding into separation cell was developed Wagner in 1917 (US, 1235083). And finally, the first column apparatus with a counter-current of slurry and air was developed by M. Towne and S. Flynn in 1919(US, 1,295,817). ("

Jan 1, 2018

By J. A. Venter

Mineralogical studies indicate the Pt-Pd-Bi-Te class to react poorly on the flotation stimuli and indications are that these minerals are slow floaters. However, recent studies performed on a number of minerals from this class indicated strong interactions with potassium ethyl xanthate resulting in the formation of dixanthogen (only one of several xanthate species). The poor flotation response is not a result of poor interaction of xanthate with the surface. It is proposed that the oxidation products of sulfides in the process water interact with the PGM surface. To test this, the effect of thiosulfate (an important oxidation product of sulfides) was investigated by employing electrochemical measurements and FTIR spectroscopy. The electrochemical investigations indicate no strong effect of thiosulfate on the interaction of xanthate with the minerals surface as well as the reduction of oxygenthiosulfate is likely not responsible for the poor flotation response of these minerals in industrial plants.

Jan 1, 2014

By M. Saghaeian, R. Hejazi, R. Barreiro, M. Tavousi, M. Ahadi, O. Asghari

"Banded iron formations are the major iron source for producing high grade concentrate. BIF are generally lower grade and more difficult to extract. In order to know how best to process BIF ore, it require comprehensive knowledge on ore bodies even in the early stages of the mining process. Geometallurgy combines geological and mineral processing information and allows for higher flexibility in response to changes in the plant feed when mining different parts of the ore. This can lead to economic benefits, owing to improved plant operation, yet is time consuming and correspondingly costly. The main focus of this paper work has been to develop a comprehensive geometallurgical testing framework for developing Yogi BIF low grade magnetite deposit located at Western Australia. In order to provide successful geometallurgical mapping, was collected data from several different disciplines (geology, chemistry, mineralogy) and parameters (physical properties, metallurgical response and geotechnical measurements) during drilling activities and test work. The investigation shown magnetic separation behavior of material had high variation and is most important element in the proper design of ore beneficiation plant. This paper provides an improved and efficient magnetic separation test methods used for the investigation of separation behavior and variability of the Yogi Ore deposit and evaluates their applicability and potential in the geometallurgical context. In this paper a small-scale magnetic separation has been developed that allows estimating from single pass separation test using small amounts of sample material. Verification of the evaluation method and validation was done with different mineral systems."

Jan 1, 2018

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

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

Jan 1, 2018

By D. B. Mazzinghy, D. C. Rocha, H. B. Miller

"The use of ball mills for fine grinding is an inefficient process and has contributed to the increasing popularity of vertical stirred grinding mills in the minerals industry. Over the last decade, the performance and energy efficiency of stirred milling technology has become a preferred alternative to ball mills for fine and regrinding operations. The difficulty encountered in fine grinding is the increased resistance to comminute small particles when compared to coarse particles. Therefore, increased energy inputs are then necessary to raise the number of stress events in a mill to contribute to the comminution of fine particles. This work discusses the effect of operating conditions on the amount of fines produced and torque readings in a screw type batch laboratory vertical stirred mill. A time-based population balance model (PBM) was used to empirically analyze the performance of a vertical mill and to calculate mill breakage parameters for the different operating conditions tested. The results indicate the possibility of applying population balance model to the vertical stirred mill to predict product size distribution with acceptable accuracy. The obtained breakage function shows that the main breakage mechanism in this vertical stirred mill is by attrition, and that the selection function changes with experimental conditions within the mill. Higher agitator velocities are also seen to promote an increase in the degree of attrition between grinding media hence particle selection and fines generation increase.INTRODUCTION Stirred milling technology has been firmly established in the last 20 years as superior to ball mills for fine and regrinding operations due to its superior energy efficiency (Jankovic, et al., 2006). Stirred mills are now commonly used in many sectors of the mining industry, though they have been used in other industries for many years (Stehr & Schwedes, 1983). This technology has proven to be more energy efficient with greater opportunities for future optimization in both fine and coarse grinding."

Jan 1, 2018

By D. Izerdem, S. L. Ergun

"Beneficiation of the finely disseminated valuable minerals has been an important issue in the mineral processing field for decades. Treatment of the fine materials becomes difficult with using traditional gravity concentration equipment. To investigate particles behavior in a commonly used conventional gravity concentration equipment, a comprehensive study was undertaken in a plant, which only consists spiral concentrators as concentration units. Spiral concentrators require relatively coarse material to effectively concentrate valuables as well as offering greater simplicity for especially higher grade feeds. In the current work, chromite ore (d80 = 290 µm) was treated using spiral concentrators and the performance of spiral concentrators was examined. The design of the separation circuit comprised of rougher, cleaner and scavenger stages. The resultant fractions produced by each separation unit and feed samples were analyzed to identify the particle sizes, mineral liberations and chromite content. Grade and recovery comparisons were presented in size-by-size manner and the separation tendency of the particles were determined in varying feed rate conditions. The overall results indicated valuable mineral loss of the plant and alternative suggestions were pointed to reach the target values.INTRODUCTION Spiral concentrators are simple low energy consuming devices, which are generally used for pre-concentration of the minerals. They are cost efficient equipment separating minerals mainly based on density differences of the minerals. The adjustable splitters remove the concentrate as the remaining stream continues to move down the spiral. Separation on a spiral is achieved through a combination of forces that act on particles as they move down the trough of the spiral. The main forces known to act on the particle on a spiral are the gravitational force, centrifugal force, hydrodynamic drag and Bagnold force (Atasoy and Spottiswood, 1995; Burt, 1984). Since the classification in a spiral concentrator depends on particle specific gravity and size, the operation of spirals can be analyzed using size recovery or partition curves (Bazin et al., 2014). Spiral concentrators possess multiple design parameters for a variety of applications. The design parameters that govern the performance of the spiral can be identified as the diameter, number of turns, slope, pitch and the profile of the trough. For an efficient separation on a spiral concentrator, the properties of the slurry flowing on a spiral, ore texture, percent solids and flow rate play important roles."

Jan 1, 2018

By M. N. Abdusalyamova

The Republic of Tajikistan has large mercury-antimony deposit. The Republic takes the second place in the countries of the CIS by having antimony recourses or the fourth place in the world. Recently, on the mine bottom horizons the resources of gold were found. Gold in the data ore is submitted as nanosize particles. Results of ores enrichment of bottom horizons of Djijikrut deposit are obtained by a method of flotation. The flow sheet includes the rougher flotation, two scavenging flotation and two cleaner flotation. As a result of enrichment of ore, the mercury-antimony concentrate with the contents of 51.5% of antimony and recovery 90.3% from ore with the content of mercury of 3.5% was received. The investigation of thallium, selenium, and tellurium distributions on products of enrichment was carried out. The most effective reagents are a mixture of oksafore and butyl xanthogenate. While applying this mixture of reagents it is possible to refuse of the use of activator - nitrate lead. The behavior of gold is in details investigated during enrichment. To collective flotation concentrate is extracted only 30% of gold. The basic quantity of gold concentrates in tailings of flotation and is not taken by existing traditional methods. The alternative innovative technology of gold extraction was created. Various methods of roasting of a collective mercury - antimony concentrate oxidizing and reducing are investigated. Vacuum distillation of concentrate allocation in serial sublimates mercury and antimony was designed. In the received calcine concentrates gold. At additional roasting of a calcine up to 900°? concentration of gold makes 30.6 g/t. The offered innovational technology in a complex allows to process ores and concentrates unique mercury-antimony?gold bearing raw material. Keywords: ore, concentrate, flotation, cyanidation, roasting, mercury, antimony, gold

Sep 1, 2012

Froth flotation is an industrial process commonly used for the separation of mineral particles. Bubbles sparged in a pulp collect and carry hydrophobic particles to the top layer of a flotation cell, the froth zone. There is a strong correlation between the stability of the froth phase and the flux of solids. However, flotation units placed in series operate, as a whole, in a non-steady state regime with the concentration of particle decreasing from one cell to the next resulting in a decrease in froth stability, which can compromise the recovery of valuables. Organic chemical reagents, frothers, are generally added to prevent fine bubbles from coalescing and to increase the stability of the froth phase. Frothers represent the second largest group of mining chemicals. It is crucial to understand the resulting properties of the frother on the froth phase in order to select the most suitable reagent for a particular operation. The bubble coalescence dynamic of three different surfactants, 1-pentanol, poly (propylene glycol), and tri (propylene glycol) methyl ether, were investigated in this study. In the first stage, the stabilisation mechanism of bubbles in a solution of surfactant was investigated using a specifically designed experimental setup. The coalescence behaviour of bubble pairs was recorded using high-speed video imaging in which information such as the coalescence time and the deformation of the resultant bubble upon coalescence could be extracted. The results were then compared between the different surfactants for several concentrations. It is shown in a study that the coalescence time increases with surfactant concentration until the Gibbs-Marangoni effect is suppressed by bulk diffusion. Conversely, the oscillation of the resultant bubble was found to be affected only at concentrations at which the film is saturated. The implications of the effects of surfactant type and concentration on the coalescence time and bubble oscillation in froth flotation are discussed. Keywords: froth flotation, frother, bubble coalescence

Sep 1, 2012

By A. Mainza, H. Hill, L. S. Bbosa

"Impact breakage is the most elementary size reduction mechanism in comminution devices. In comminution research, characterization of breakage is primarily concerned with the energy expended to cause it. The main challenges of this approach have been quantifying the actual energy requirements of impact breakage and developing mechanistic models to accurately describe the process. For engineering load analysis, fracture is characterized in terms of strengths such as yield stress and ultimate tensile stress, which govern the maximum loads specific materials can be subjected to before irreversible inelastic deformation and subsequently complete fracture occur. With this approach, the main challenge has been to elucidate the underlying mechanism, in the means that the load causes weaknesses in the material microstructure to act as sites for stress concentrations, leading to crack initiation, propagation and eventual failure. Studies dedicated to investigating particle fracture under impact loading have led to the development of several devices for conducting breakage characterization tests. These devices include the drop weight tester, split Hopkinson pressure bar, rotary breakage tester and the short impact load cell. All these have different particle loading and breakage methods, and thus can yield distinct information which can be compiled together to study a material and the nature of breakage. This work analyses the single impact breakage data obtained across the listed devices. A homogenous ore commonly known as blue stone is used for all breakage tests. The work is conducted using standard procedures specific to each device as closely as possible. Drop weight and rotary breakage tests were used to obtain hardness parameters based on an existing t10 breakage model, while split Hopkinson pressure bar and short impact load cell measurements provided properties based on conventional engineering load analysis. The results were used to highlight the significance of the loading geometry, impact mechanism and impulse on the extent of breakage."

Jan 1, 2018

By Victor Avdokhin, Ivan Kovlekov

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

Jan 1, 2003

By Jurgens J. Louw, Vincent C. Smith, Gareth C. Smith, Agit Singh, Dave G. Hulbert

"The flexibility of the PlantStar control platform has enabled Mintek to investigate and easily develop new control strategies for both milling and flotation. This includes a Solids Feed Controller, a Safety Limit Controller, Mill Power Optimiser and Flotation Optimiser, amongst others.The solids feed controller was developed for minerals processing plants using a specialised time delay compensator. Using conventional time delay compensators that are purely model based, results in robustness problems due to model uncertainties. The Mintek Solid Feeds Controller makes use of a plant model, but compensates for model inaccuracies, giving more controller stability and a more robust delay compensation algorithm.The safety limit controller has been developed to switch smoothly between normal and safety control loops without bumping the process. The safety loop output is chosen in accordance with a predefined list of priorities and whether the respective constraint boundaries are exceeded.The Mill Power Optimiser helps to find the power peak on the mill power curve. This insures maximum grind with maximum throughput. It also prevents power dips due to mill overloads, making the milling circuit easier to operate.The flotation optimiser algorithm analyses trends of all accessible variables in the process. The algorithm uses this information to calculate operating conditions that will control the residence times, mass pulls and circulating loads within a flotation circuit to a specified setpoint. Research is being done to now optimise these setpoints in order to achieve better recovery."

Jan 1, 2003

By Häkkinen Antti, Salmimies Riina, Matveinen Maria

"Tailings generated during the upgrading of ore present a major challenge for the mineral processing industry. On one hand, the processing of tailings requires added capital input. On the other hand, increased difficulties in obtaining permits for dams and landfilling and increased costs associated with storage and tailings management also result in increased costs. To promote sustainability and make tailings management economical, added value must be generated from the waste material. This might be possible through the recovery of the metal values in the waste. This work discusses the possibilities of recovering metals from multimetal tailings through leaching in a stirred tank. The characteristics of the tailings are crucial and the distribution of the metals within the different size fractions is used to identify the most attractive route for the hydrometallurgical step. Leaching of nickel and copper is further investigated using acids at different concentrations. The leaching of base metals is possible at acidic conditions. Increased temperature and concentration of the leaching agent promote the dissolution of the metals, as could be expected. With simultaneous dissolution of several metals the dissolution mechanisms are difficult to identify. Furthermore, as several metals, not all of them being target elements, are leached another challenge arises from the selective recovery of those metals from the liquid phase."

Jan 1, 2014