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By D. Berman, A. Brodt

"Delivery of all volume of mined mass on the terrestrial surface results not only in irrational power expenses on moving of huge volumes of dead rock as a part of initial raw materials (especially vertically) on long distances, but also necessities of storing tailings in open-air. Thus, in bowels of earth, huge volumes of the developed space are formed. However, the nature doesn't suffer emptiness. As consequence, through the process of underground mining works, in earth bowels starts intensive development of rocks dislocation processes involving subsidence of terrestrial surface, and with it, begins irreparable damage every objects which are on that territory. Highly effective new methods of underground concentration of the various minerals, which deliveries of only target component on terrestrial surface integrally connected with transport process in stream and subsequent deliveries to destination in continuous mode by the long distance hydrotransport, allow not only to eliminate a construction of concentrating factories on the surface, but also storing of tailings of concentration process on open-air preventing dislocation of rocks, thanks to operative placing tails in the underground developed space. Surely, the main problem in the development of such gravity dressing technology is the problem of finding the optimal formula for the heavy liquid that will fill such system in close connection with the procedure of its full regeneration. The requirements for such liquid are being non-toxic and cheap. This question was solved successfully."

Jan 1, 2014

By Ruiyang Zhang, Ping Fang, Dezhou Wei, Shuling Gao

A CFD based numerical simulation of flow characteristics of hydrocyclone was conducted with different structural and operational parameters to investigate its distribution characteristics and influencing mechanism. The results show there exist several unsymmetrical envelopes of equal vertical velocities among both upward inner flows and downward outer flows in the hydrocyclone, and cone angle and apex diameter have remarkable influence on the vertical location of the cone bottom of the envelop of zero vertical velocity. It is also found that some tangential velocity isolines exist in the horizontal planes located in the effective separation region of hydrocyclone, and feed pressure has almost no effect on the distribution characteristics of both vertical velocity and tangential velocity of flow in hydrocyclone, however the magnitude and gradient of tangential velocity are made increased obviously, so as to make the high density particles motion velocity to the wall increased and to make the cyclonic separation effect improved. The simulation results also show when the apex diameter increased, the pressure of the fluid field decreased, however the pressure grads in the apex district increased, and the degree of changing is different as the cone angle, which showed some interactive influence of cone angle and apex diameter on the fluid field of hydrocyclone. While the feed pressure also has almost no effect on the pressure distribution characteristics, however the its magnitude and gradient are made increased accordingly, which can improve the separation accuracy according to particle density.

Jan 1, 2014

By T. N. Matveeva, T. A. Ivanova

"The article presents the results of the research aimed at development and testing of new effective reagents – collectors and green modifiers for more complete extraction of gold and platinum to concentrates at reduced loss with waste products. The main deposits of Au and PGM ores of Russia and abroad are presented by refractory raw material with the non-uniform finely-interspersed sulfide mineralization, submicron gold and platinum, the low metal content, non-uniform distribution of valuable minerals. and show low indicators of recovery. The main losses of precious metals (up to 15 %) at flotation are associated with thin slam tailings because of inefficiency of standard reagent modes.In the paper, the new trends in design of collecting agents for extraction of gold and PGM sulfide minerals and their application in flotation tests are substantiated. The original technique for obtaining the modified collector reagents – dithiocarbamate, dithiophoshpinate and dithiazine, incorporated non-ionic compounds that are able to generate stable complexes with gold and platinum has been developed. A novel class of collectors – cloud point polymers showed high flotation recovery of fine particles of gold and platinum. The original technique to create the mineral samples of natural sulfides with ""invisible"" or sub-micron gold on their surface designed helped to indicate the mechanism of selective adsorption of novel agents on Au and Pt-sulfide minerals. Extractive UV spectrophotometry, potential measurements, X-ray phase and spectral analysis, scanning electronic microscopy (SEAM), laser SIM and AFM microscopy were applied to analyze the adsorbed layer of modified reagents on the mineral surface. Selective hydrophobic covering on the surface of micro- and nanoparticles of noble metals provided an increase in their extraction during flotation. New reagent modes of modified collectors and green modifiers were tested in scaled-up laboratory flotation and the results obtained demonstrated the increased quality of the concentrates in terms of gold content by 1.5 times and higher gold recovery by 1.5-5%. The studies have been supported by Grants of the President of RF “Scientific School of Academician Chanturiya” NSh-220.2012.5; NSh-748.2014.5."

Jan 1, 2018

Mineral flotation is effective over a relatively narrow particle size range of approximately 10 µm to 150 µm. If the upper particle size limit can be increased, however, a run-of-mine ore may be coarse ground, and only the middlings are ground further to achieve required grades. This will result in significant energy savings and increased throughput. In this communication, methods of increasing the upper particle size limit will be discussed on the basis of a flotation model that can predict flotation from both hydrodynamic and surface chemical parameters. An example of increasing flotation recovery by control of a chemistry parameter is given.

Jan 1, 2014

By A. P. Purgin, M. G. Viduetsky, I. F. Garifulin

"The combined treatment process for mine, tailings storage facility, quarry, circulating, and waste water in the mining and metals industry brings together the conventional chemical treatment processes and pneumatic flotation cells of the KFM series. The key principle of the process is preparing the water for treatment by saturating with finely dispersed air bubbles in the flotation cell blowers. Gas-air lift dispersers located in the lower part of the cell body additionally saturate the cell’s contents with finely dispersed air. Due to the residual content of flotation agents in the treated water, hydroxide ion-air aggregates form at the aerator outlet, supporting the efficient precipitation of hydroxide ions of heavy non-ferrous metals, calcium and magnesium ions. This process was tested in the pilot plant KFM-180 with a raw (untreated) water capacity of up to 18 m3/h per 1 m3 of the flotation cell volume using a mixture of the tailings storage facility and mine water from JSC Safyanovo Copper. The treatment process included raw water treatment with lime, aeration in KFM cells, and filtration in a sorbent bed. The content of metal ions in the treated water is lower than in the feed water by a factor of up to 170,000 and approaches the standards: aluminum 0.016-0.02 mg/l, copper 0.0043-0.0045 mg/l, zinc 0.049-0.052 mg/l. circulating water of Soryin Tailings Storage Facility at JSC Svyatogor. The treatment process included raw water treatment with lime and alkali, aeration in KFM cells, and filtration in a sorbent bed. The content of metals in the treated water is lower than in the feed water by a factor of up to 9000: copper 0.022 mg/l, zinc 0.012 mg/l, iron 0.012 mg/l, manganese 0.015 mg/l, nickel 0.132 mg/l, arsenic 0.016 mg/l. Water hardness is significantly lower: calcium - 12.6 mg/l, magnesium - 1.1 mg/l. This process can be used in the treatment of mine, quarry, tailings storage facility, and circulating water at mining and non-ferrous metals projects."

Jan 1, 2018

By Valentine Chanturiya, Irina Khabarova, Maria Ryazantseva, Igor Bunin

"XPS investigations of the influence of HPEMP - treatment duration on the surface composition for natural chalcopyrite and sphalerite are described. HPEMP is a video pulse with a nanosecond front lasting between 5 and 10 ns. The electrical field component can reach 30 kV, whereas pulses repetition frequency is 100 Hz. In general, the formation of metal-deficient surfaces, polysulphides or elemental sulphur and oxides/hydroxides, were determined during the treatment for both sulphides as well as the essential differences of the way of mineral surface transformation during the treatment. The chalcopyrite surface shows the formation of elemental sulphur under the HPEMP treatment at 103 pulses while appearance of unstable sulphite species was detected at the chalcopyrite surface within 5 seconds (0.5•103 pulses) under the same treatment conditions. The results indicate that the quantity of adsorbed water (at.%) is changed considerably during the HPEM - treatment depending on treatment duration for both minerals. The concentration of water onto the chalcopyrite surface decreased during 30 seconds (3•103 pulses) of the HPEMP - treatment and it rose after the treatment at 5•103 pulses. The inverse dependency was obtained for sphalerite surface. Single mineral flotation tests have shown the significant increasing of the minerals recovery."

Jan 1, 2014

By Adam Jordens, Olga Kuzmina, Christopher Marion, Kristian Waters

"In order to meet the growing demand for non-Chinese rare earth suppliers many new rare earth (RE) mineral deposits are currently under development, however these deposits typically include many minerals for which there is little processing information available. One of these deposits is the Nechalacho deposit located in the North West Territories of Canada. This deposit contains multiple RE minerals including bastnäsite, zircon, fergusonite, allanite and monazite. The work presented here investigates the use of different classes of flotation collectors (carboxylic acids, hydroxamic acids, phosphoric acids) typically used in RE mineral flotation to float the Nechalacho ore directly. Flotation tests are also conducted as the final step in a beneficiation process incorporating centrifugal gravity concentration and magnetic separation. This combination of centrifugal gravity concentration and magnetic separation rejects low specific gravity gangue minerals such as K-feldspar and plagioclase and concentrates high specific gravity minerals such as magnetite and hematite. The removal of low specific gravity gangue helps to improve flotation and the removal of ferromagnetic iron oxides is important prior to flotation using certain chelating collectors."

Jan 1, 2014

By Wolfgang Öfner

Many technical processes also yield dusty residues which usually contain appreciable amounts of valuable matter. Often they also accumulate substances detrimental to the process. Dumping them entirely in landfills wastes raw material and causes high disposal costs, but recycling them without prior treatment is often not feasible. Physical separation processes are preferable because of their rather low energy demand. In order to develop such treatment systematically, the residues must be characterized properly. The technique for such a characterization is taken from mineral processing: perfect fractionation according to continuous properties of the particles supplemented with chemical analysis are used for plotting the Henry-Reinhardt chart. This represents the benchmark for assessing actual separation processes and tests. Their results are compared in terms of ?selectivity? and plotted in the kappa chart. In this paper, Henry-Reinhardt chart and kappa chart are applied to several different types of residues from iron and steel production and show their potential for being upgraded before reutilization in the production process. This approach is suitable for virtually all dusty residues from other industrial processes as well. Keywords: residue, dust,iron and steel, process development, Henry-Reinhardt chart, kappa chart

Sep 1, 2012

By U. S. Chattopadhyay

The estimated requirement of the nation by the year 2020 is approx. 80 Mt of steel and more than 0.2 million MW installed capacity of the electricity, thereby increasing the consumption of the coking and non-coking coal, which is expected to be in tune of about 75 Mt & 500 Mt respectively. One of the major deleterious factors in achieving the goal is the deteriorating quality of the feed coal used in both steel and power industries. Indian coking coals, in general, are typified by high ash, high inert (both organic and inorganic), low rank, low reactive macerals content, heterogeneous petrographic make-up, inferior coking properties and poor amenability to washing, thereby necessitating suitable washing measure. Coke-based steel industries in India require washed coking coal containing ash % varying between 17-19. The situation demands taking on immediate challenges to fill up the gap between the requirements and supply of coking coal. This paper reviews the R&D attempts in this laboratory and throws light on the key measures as long-term solution to the problem. Search for alternative source of coking coal, like LVC coal and their judicious preparation technology. The low volatile coking coal (LVCC) constitutes about 50% of the total coking coal reserves in India. These coals are characterized by high raw coal ash content (37 to 40%) and very difficult washability potential. If these coals are treated in the existing washeries, which are generally 2 or 3-product systems, the cost of clean coal is high as the byproduct sale value is low. It has been proposed to produce a new type of by product, which enjoys high demand and good coking properties.

Sep 1, 2012

By G. Venkateswara Rao

The jigging of ferrous ore to produce higher-grade products has been practiced for many decades. This is due to easy separation, a beneficial trade- off between operating cost and reduced yield relative to Dense Media Separation (DMS). Jigging becomes prominent for beneficiation of iron ores in the coarser size range. At present drive is towards the use of under bed air pulsed jigs for the beneficiation of ferrous ores. The main advantage is that the under bed air pulsed jigs are capable of generating the large pulse of amplitudes required to fluidize a deep bed of heavy ores particularly lump iron ore up to 40mm size. The major jig parameters effecting the jigging operation are bed height, shape of the pulse, residence time, operating pressure, valve cycle time and water flow rate. With the pulse shape set correctly for optimum stratification rate, even it is still necessary to provide enough residence time, to ensure the difficult material will take time to migrate to the expected layer in the bed. In order to find the Jig Stratification Index (JIS) parameters like bed height, operating pressure, water flow rate, cycle valve time and shape of the pulse were optimized first by conducting various tests. Typical Iron ore samples from Odisha (both lump and fines) were subjected to stratification studies at residence time of 1, 5 and 15 minutes. Jig Stratification Index (JSI) for both lump (0.30) and fines (0.20) were determined by using APIC Jig. The maximum possible JSI was calculated by using heavy liquid separation test (0.42 for lump and 0.24 for fines). It is found that the jig bed JSI is less than the Heavy liquid JSI for both lump and fines. The ratio of Jig bed JSI to the heavy liquid JSI is 0.83 for lump and 0.71 for fines. The JSI and ratio of Jig bed JSI to Heavy liquid JSI are low for fines due to fluid turbulences causing some degree of remixing in the jig bed. The fluid turbulences are more for fines than lump, hence jigging of fines is difficult and challenging. Keywords: sub grade iron ore, gravity separation, jigging, apic jig, stratification, residence time, jig stratification index

Sep 1, 2012

"Wet low intensity magnetic separation has been used for the recovery of magnetite for decades. As high-grade reserves continue to decline, low grade magnetite ores are being targeted for iron production. Low grade magnetite mineralisation is typically fine grained and requires fine to ultrafine grinding (P80 40 - 30 µm) to liberate it from, predominantly, silica/silicate gangue matrices. Grinding to such particle sizes requires high power consumption and produces excessive fines which impact negatively on wet magnetic separation and tailings dewatering. In addition, the dearth of fresh water for mineral processing in arid areas impacts negatively on the economic viability of low grade magnetite projects. These challenges have motivated innovation in dry magnetic separation technologies for the beneficiation of magnetite that can be economically applied on a large-scale. Such technology has been developed in the Cyclomag Planar magnetic separator (PMS) invented by South Australia-based Christopher Kelsey of IMPTEC P/L. The significant gangue mineralisation associated with magnetite ores in South Australia is quartz. In this study, the performance of the Cyclomag PMS on the recovery of magnetite mineral from magnetite-quartz blends was investigated. Magnetite-quartz blend were subjected to the PMS at varying control parameters - magnet discs rotation speed, inlet airflow and feeder speed. The study showed a successful dry separation of magnetic mineral from non-magnetics using the Cyclomag PMS. The PMS has potential to effectively recover magnetite mineral."

Jan 1, 2018

By D. J. Borrow, K. van Netten

"A fine coal tailings feed was selectively agglomerated using a concentrated water in oil emulsion binder consisting of 95% aqueous phase and 5% organic phase. The purpose of the study was to investigate a continuous system in plug flow, providing a rapid beneficiation technique with high selectivity and recovery. The development of the novel binder was undertaken in previous work in a batch system consisting of a high-speed blender. In this previous work, it was found that agglomeration could be achieved in 3 s, providing the binder was pre-dispersed. Furthermore, it was found that, depending on the feed, only ~1 wt% of oil was required to achieve agglomeration, some 10 times less than required in traditional oil agglomeration. In a more recent study, the technique was adapted into a continuous process. Due to the rapid speed of the process using the emulsion binder it was found that a simple flow constriction within a 1 inch pipe was sufficient to achieve the selective agglomeration observed in the batch system. In this previous study, a coal feed consisting of a flotation product was agglomerated at a superficial slurry velocity of 1.3 m/s using a partially closed ball valve as the flow constriction. In the current study, a feed consisting of fine coal tailings with an ash content of 50.1% was used to establish the influence of superficial slurry velocity on the agglomeration process. The superficial slurry velocity was varied between 1.3- 4.2 m/s, while maintaining a constant pressure drop of 100 kPa across the flow constriction. The flow constriction consisted of a partially closed ball valve. It was found that increasing the superficial slurry velocity across the flow constriction reduced the amount of organic liquid required to achieve agglomeration. Under the optimum conditions, a combustible recovery of 80.4% was achieved at a product ash content of 9.6%. This work demonstrates a valuable product can be rapidly produced from tailings material using the novel emulsion binder. INTRODUCTION A significant opportunity exists to recover fine coal from material that is currently classified as waste. This waste material, also called tailings, is currently considered not economic to process due to its high ash content, low solids concentration, and the fine size of the particles. Thus, for this opportunity to be realised, a process is required that is highly selective and has the ability to economically recover fine particles at high throughputs. The technique of oil agglomeration has previously been considered as a candidate for the recovery of fine coal, as it is highly selective and has no lower limit on the size of particle that can be recovered (Capes and Jonasson, 1989). However, the cost of the oil required as the binding agent in the process has proven to be a significant barrier to any long-term applications (Swanson, Nicol, and Bensley, 1977). Recently, however, Yoon and co-workers have developed an ultrafine coal separation process that utilizes an oil phase for the recovery of the hydrophobic coal particles and have implemented an oil recycle to greatly reduce the consumption and thus cost of the oil (Yoon et al., 2016)."

Jan 1, 2018

By Luis Bergh, Juan Yianatos, Luis Vinnett

"Process automation as an engineering discipline is more than control systems since it includes industrial instrumentation, such as sensors, transmitters and actuators, as well as control and supervision systems, collection and transmission of data and real-time software applications to supervise and control the operation of plants or industrial processes. In the last several decades, accelerated technological development has provided a variety of software and hardware tools to aid development, maintenance and continuous improvement of automated systems. These developments however seldom reach their full potential in real plants. There are many factors to be considered, among them human capital specific training and the organization model. In this paper, a methodology for training engineers in advanced control and supervision of flotation plants is presented based on study of the application of these technologies in hybrid pilot plants. Since experimentation in real plants may present undesirable risks and costs, and simulation studies are usually limited to some unrealistic conditions, a laboratory where on-line measurements of the hydrodynamic behaviour of a pilot plant is mixed with phenomenological models has been created. In this form, an environment as close as possible to a real plant can be recreated. A flotation column and a circuit of three pneumatic cells are fully instrumented and connected to a PLC and PC network. In the control room, students learn applications of classical PID control in a DCS environment, advanced predictive control, on-line process operation diagnosis, fault analysis, virtual sensors and expert-fuzzy systems. Several undergraduate and graduate courses and theses are supported by this Process Control Laboratory infrastructure. Examples of these applications are discussed."

Jan 1, 2014

By B. McFadzean, S. Geldenhuys

"Dynamic froth stability tests have found widespread application to quantify froth performance. However, little to no attention has been given to scale parameters in the performance of these measurements. One of the most frequently changing scale parameters in the laboratory scale is the column diameter as this directly influences the amount of material needed for testing. Four different column diameters (50, 100, 200 and 300 mm) were used for this study. Column diameter experiments were done on an industrial scale by means of manual tracking of froth growth versus time. An increase in measured dynamic stability was seen with increasing froth column diameter, which reached a limiting value at large column sizes. It is thought that this behaviour is controlled by the differences in drainage rates of the bulk froth compared to froth in contact with the wall. The column diameter required to represent full-scale froth stability is proposed. A ratio of column surface area to total bubble surface area was used to correct for different column diameters.INTRODUCTIONThe froth phase in flotation contributes significantly to the overall performance of the process (Zanin, et al., 2009). Numerous parameters have been investigated to quantify froth performance, most notably froth recovery (Feteris, et al., 1987; Seaman, et al., 2004; Vera, et al., 1999). Experimentally gathering data to determine froth recovery is challenging and for this reason froth stability has been highlighted as a possible alternative.Froth/foam stability is defined as the time of persistence of the froth/foam and is affected by numerous factors, such as: drainage of the liquid in the lamellae (gravitational and capillary), viscosity at the bubble surface, thickness of the electrical double layer and gas diffusion through liquid films caused by pressure differences between bubbles (Aktas, et al., 2008; Beneventi, et al., 2001). It is well documented in both froth and foam literature that froth/foam stability will heavily influence the performance and appearance of the froth/foam phase (Ata, 2012; Farrokhpay, 2011; Weaire, et al., 2005). Experimentally this has been explicitly proven as an increase in froth stability, characterised by water recovery, usually results in an increase in both valuable mineral and solids recovery (Wiese, et al., 2011; Banford, et al., 1998)."

Jan 1, 2018

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 A. Mainza, I. Govender, J. Waters

"The study of the properties of mineral processing suspensions is important in understanding how a circuit might behave. As soon as the predominantly dry ore enters a wet milling stage the ore properties undergo changes as a ‘slurry’ is created. Slurries can be classified in terms of their physical properties (particle density, solids concentration, particle size and size distribution, particle shape), and their flow properties such as rheology. Slurry flow regimes are classified into true homogeneous, pseudo homogeneous, heterogeneous and fully segregated, and only true homogeneous and pseudo homogeneous suspensions can be characterized by their flow structure. A class of the heterogeneous regime are the so-called dense phase or settling slurries - those which result in a clear water surface on standing, although they may approach a pseudo homogeneous state if suspended for a sufficient period of time. They are usually extremely difficult to characterize by their rheological properties alone and the rheological characterization of these slurries has always posed a problem, especially at higher concentrations. Previous rheological studies have focused on the individual concentrator units dealing with milling, classification, pumping, flotation, fine grinding, thickening.In this work an attempt was made to characterize two ore types (copper and a Platreef platinum ore) using a custom built Paterson and Cooke tube rheometer, at concentrations up to 43% by volume. After applying a turbulence correction, results showed Bingham plastic behavior. A conventional vane rheometer was then used to compare the rheological behavior of platinum concentrator streams. A size criteria was used to identify any rheologically dominant streams."

Jan 1, 2014

By Lei Pan, Roe-Hoan Yoon

"Direct force measurement for bubble-particle interaction has been difficult due to bubble deformation, which makes it difficult to know the separation distances between the two macroscopic surfaces. In the present work, we have developed a method of monitoring the deformation accurately, while directly measuring the interaction forces. In effect, we can ‘see’ bubbles interacting with mineral surfaces under different hydrodynamic and chemical conditions and determine both the hydrodynamic and surface forces involved. In the present work, a high-speed camera has been used to record the optical interference fringes of a thin liquid film (TLF) of water formed on a mineral surface. The recorded fringes are then used to reconstruct the spatiotemporal profiles, from which one can determine the hydrodynamic pressure using the Reynolds lubrications theory. From the forces directly measured in the present work and the hydrodynamic pressures obtained from the fringes, we have determined the disjoining pressure. The results show that air bubbles interacting with hydrophilic surfaces form stable TLFs with zero contact angles. The TLF formed on a hydrophobic surface thins fast, form a ‘pimpled’ film, and ruptures to form a finite contact angle. The new information obtained in the present work may be useful to better understand the role of hydrodynamic and surface forces affecting bubble-particle interactions."

Jan 1, 2014

By Darryel Boucher, Raymond Langlois, Neil Rowson, Kristian Waters

The Knelson Concentrator is a centrifugal gravity concentrator composed of a high speed rotating bowl into which a mineral slurry is fed. The rotational motion creates a centrifugal acceleration up to an equivalent of 200 G. Under this acceleration, particles enter fluidised riffles along the side of the bowl, with the fluidisation allowing for the substitution of dense material for less dense. The separation mechanism is not fully understood and questions remain on the optimal residence time, slurry feed parameters and bowl surface profile to achieve a better separation. The positron emission particle tracking (PEPT) technique has been applied to record the motion of a -1700+1180 µm particle of a quartz-gold matrix, labelled with 18F radioisotope while it undergoes concentration inside a 3" laboratory scale Knelson Concentrator (KC-MD3) operated at 60 G. The slurry used was composed of quartz and magnetite. Particle trajectories during the first stage of the concentration process where the heavier particles centrifuge through the increasingly dense slurry towards the riffles of the bowl are shown with respect to time. This work reveals new information on particle motion inside the Knelson Concentrator and the results will be used for validation of developed separation model as well as optimisation of a centrifugal concentrator’s performance.

Jan 1, 2014

By A. Kogelbauer, A. Stadtschnitzer, A. Boehm, F. Schillab

"The paper covers the design and implementation of an industrial dense medium cyclone plant for carbonaceous iron ore, the proving of efficiency as well as the development of a predictive model for plant control. The VA Erzberg GmbH mines about 12 Mio.t of carbonaceous rock ore at the “Steirische Erzberg”. Due to increased demand of the Austrian steel plants, the production of ore concentrate was raised by 30 % up to 3.0 Mio t/a during the last 5 years. One of the projects to realize the increase in capacity at improved concentrate quality was the implementation of a dense medium cyclone plant for the fine size fraction – 8 +1 mm replacing the former dry permanent magnetic drum separators. By physical separation the siderite variety “spateisenstein” (42% Fe) of a density of 3,8 g/cm³ is separated from ankerite (10 – 17% Fe), the second iron bearing carbonate with a density of 3,2 g/cm³, dolomite, calcite and silicate bearing schists. The feasibility of the process was proven by the test results obtained from a test rig, that was constructed and operated in close cooperation between the Chair of Mineral Processing, Montanuniversitaet Leoben and VA Erzberg GmbH. The density separation surpassed the efficiency of magnetic separation clearly shown by •- values. The plant performance tests (capacity 120 t/h) verify the cut densities defined by Tromp T50 -values and the assigned efficiency found in the pilot tests at varied settings of media density, pressure drop, cone angle and apex diameter. The test rig as well as the final process will be presented. In order to create a tool to predict the performance of the DMS in the centrifugal field at various settings for varying feed composition the experimental results from size and density testing are analyzed in a modified way to obtain physically justified, smooth approximations for the performance curves. Models developed on coal washing plants are checked for their validity at increased densities."

Jan 1, 2018

By Richter, E. Charikinya

"Mineral processing unit models require information on particulate properties such as particle size, solids flowrate and mineralogical composition to model their operations. Process models that describe the separation process can be classified based on the level of information required from the ore, i.e. the feed stream to the separating unit. The most comprehensive level of mineral processing models is the particle-based modelling approach. Particle based modelling describes a modelling approach where mineral composition, mineral liberation and textural information of particles making up the process streams is used in modelling. The advantage of this approach is that all model streams carry particle level information (size, liberation, shape). This information is obtained by applying automated mineralogy techniques such as Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) analysis which provide accurate and detailed information on process stream particle properties. Currently the use of liberation information in modelling and simulation is rare, due to the limited number of separation models that liberation data as input. The objective of this study is to develop a particle based model for a dry magnetic separator, where mineralogical information is used directly to simulate a dry magnetic separator operation. Magnetic separation tests were carried out on high, medium and low grade magnetite ores using a laboratory magnetic separator. Streams from the separator were sampled and sized for chemical and liberation analyses. A sized mass and elemental balance around the magnetic separator was carried out. The elemental assays of each stream were converted to mineral quantities and a sized mineral balance was done. QEMSCAN measured liberation data was reconciled to the mineral balance based on mineral quantities obtained from chemical assays. This was followed by the development of a particle based model that calculates the trajectory of a single particle based on its mineral composition and textural properties. The model was tested on experimental data and was able to predict the effect of variation in process feed stream mineralogical attributes (liberation, grade, particle size) on magnetic separation performance. Results of this study highlight the benefits of the particle based modelling approach. INTRODUCTION The extraction of mineral values from ore requires liberation of the value minerals from the gangue followed by their separation. Liberation is achieved by size reduction operations (Desmond, 2008; Fuerstenau and Abouzeid, 2002). Separation of gangue material from value mineral takes place in various mineral upgrading stages such as classification, magnetic separation and flotation. In these concentration stages value minerals are separated from gangue minerals based on the physical properties of the ore particles making up the feed such as size, liberation, volume of magnetic material and density. The success of separation is related to the liberation of the feed particles, the performance of the separation technology applied, as well as the inherent characteristics of the feed material (Leißner et al., 2013)."

Jan 1, 2018