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By T. Neesse

In many cases, the use of hydrocyclone control is desirable for the stabilization of separation in the setting of changing feed conditions. Control concepts based on exact mathematical models are not satisfactory due to the complexity of the physical process. In this case, fuzzy control is a suitable solution. The data are primarily derived from an optical sensor that monitors the outside view of the free underflow stream. A throttling valve, serving as an actuator, is installed in the overflow pipe that regulates the volume split of the cyclone. Applications in closed circuit grinding and in separation plants for tunnel driving, fine sand dewatering, and classification of kaolin demonstrate the typical use of this development. Additionally, the technological characteristics of the cyclone may be improved by this control, which is mainly caused by the increased discharge capacity of the un-der flow nozzle. A further advantage is the option to operate at an optimal operation point. In many cases, this point is located at the transition spray/rope discharge. The improved operation characteristics present new options for extensive applications of fuzzy cyclone control.

Jan 1, 2014

By Valentine Chanturiya1

We have developed a classification of geochemical barriers according to their origin, i.e. natural and artificial, and according to methods and areas of application. There has been an examination of the interaction between different classes of geochemical barriers with sulfate solutions containing nickel, copper and iron. As natural barriers, carbonates (calcite and dolomites) were used. For artificial barriers, a mixture of serpentine and carbonatite, thermo-activated copper-nickel dressing tailings, and a magnesium-containing sorbent based on brucite was used. Keywords: geochemical barriers, physical-chemical geotechnologies, treatment of natural and waste water, recovery of nonferrous metals

Sep 1, 2012

By D. J. Zhao

The reduction and nitridation of preoxidized ilmenite pellets were investigated with the prospect of creating grain refiners containing titanium oxides and titanium nitride dispersoids. All the reduction and nitridation reactions were conducted in a furnace with a thermogravimetric analysis system under a H2-N2 gas mixture of 5 L/min. The ilmenite pellets were reduced at 1100°C for 4 hours under 80%H2-20%N2 gas mixture, and then respectively nitrided at 700°C, 800°C, 900°C and 1000°C for 12 hours under 10%H2-90%N2 gas mixture. The products were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), and analyzed by Energy Dispersive Spectrometers (EDS) and Electron Probe Mapping Analysis (EPMA). Iron oxides were reduced into metallic iron, and oxides of titanium were found, but titanium nitride particles were not identified in the products under the prevailing conditions.

Jan 1, 2014

By T. Damyanov

Spherical grinding media (balls) are the most widely used media for comminution of ores by grinding. A modelling simulation study of the behavior of two grinding media in the grinding process was conducted to determine the possible advantages of the new shape milling bodies called tetraballpebs. Tetraballpebs are in the shape of tetrahedrons with spherical convex walls. A three dimensional CAD model of the mill drum with a diameter of 1200 mm was used. A continuous operating mode was simulated in terms of the 3D contact elements of the model (milling bodies and mill drum). Simulation tests were carried out in a typical grinding mode and at a typical rotational speed of the drum mill (75 per cent of the critical speed in cataracting mode). Studies carried out with both grinding media include equal number of milling bodies with the same weight and volume. Having thus ensured a uniform mass of the grinding media and same number of milling bodies, and constant other conditions and process parameters, conclusions can be drawn about the influence of the shape of the milling bodies on the grinding process. A kinematic analysis of the system using CAE (computer-aided engineering) model parameterization was conducted. The controlled parameters are: ? Power draw; ? Kinetic energy of each milling body; ? Motion of milling bodies inside the drum Keywords: grinding, grinding simulation, balls, tetraballpebs, DEM, CAD-CAE

Sep 1, 2012

Opportunities to monitor and control primary grinding mill performance are strongly sought after in the mineral processing industry. Currently, limited on-line information about mill charge motion and content is available to mill operations for control purposes, leading to periods of lower throughput, instability, variable product size and accelerated mill liner and lifter wear. In response to this need, CSIRO has developed an on-line surface vibration monitor for primary grinding mills which produces data that has been shown to provide new information about the mill charge in terms of toe and shoulder position, as well as potentially key features such as the overall charge level, the distribution between rock and balls in the mill, and the impact of the charge on the mill liners and lifters. This paper outlines the key features of the on-line monitor system, particularly those relating to data transmission, data analysis, and the design of the monitor and its independent power supply. It describes the coupling of single vibration sensor data from the CSIRO on-line monitor to the actual operating conditions of a SAG mill and how the vibration response and hence mill operating conditions vary as a function of time, including during mill equipment failures such as a broken discharge grate. Opportunities for improved mill control based on the data from the on-line monitor are also discussed, as well as the implications in terms of mill processing and maintenance performance. Recently a CSIRO monitor was also installed on a ROM ball mill and analysis of the vibration sensor data from this installation is currently underway. Preliminary findings from this installation will be presented along with comparisons of generic information, such as toe position (measurement precision and operation variability) and vibration signal (intensity, sensitivity and operation variability), between this type of primary grinding mill and AG/SAG mills.

Sep 1, 2012

By A. Oleynik

The paper presents the modeling and simulation experience in field of research into the mineral row material separation. Features of the subject domain generate a need of different approaches using for modeling and simulation. The general scheme of separation modeling process and some examples of developed simulators are presented. Due to different features and standards of knowledge, different formal models should be used to describe and analyze separation processes in the frame of general scheme. The main types of simulators are modeling tools based on statistical, analytical or expert (logical) methods. Advantages and disadvantages of each method above are mentioned in the paper. Based on the studies in the field considered, an aggregated mathematical model of a separation process has been generated. The aggregated model is presented by two combined equations. The actual apparatus model is formed by substitution of the particular functional expressions of the forces acting in the apparatus into the aggregated model. The developed simulation tools are based on integration of limited experimental data and on ex-pert knowledge available on separation processes. Simulation does not allow producing an optimal, in terms of mathematics, solution. But it gives an opportunity to produce and compare quite adequate solution variants in real time. The results obtained are the theoretical and methodological base for integrated information technologies to support studies in the field of mineral processing.

Jan 1, 2014

By André Mans, Frans B. Waanders

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

Jan 1, 2003

By R. C. Miranda

Artificial vision systems are increasingly used to assist humans to perform different tasks in different areas. These systems are able to recognize patterns in complex images, which can provide multiple data. Currently, vision systems are used in both; monitoring traffic - which uses radars for vehicular plate recognition- as in metallurgical and food industries for strict quality inspections. Their use in mining occurs in measuring the speed of froth over the lip of a cell, in determining the shape and size of pellets, in obtaining from the tendency of mineral content and as a replacement for laboratory analysis of particle size. With this advanced tool, it is possible to achieve significant improvements in quality, productivity, and especially in reducing costs in pelletizing plant of iron ore. The objective of this paper is to contemplate the current situation of image analysis in the pelleting plants and glimpse at the potential applications that are being developed. This paper also presents the conception and implementation of an automatic control system of the pellets size distribution applied on a pelletizing plant of iron ore. The article demonstrates the strategy used for measuring the size distribution of the iron ore pellets, based on image analysis and the strategy implemented on advanced process control, which shows substantial gain on plant performance.

Sep 1, 2012

By A. Morrison, D. Mesa, P. R. Brito-Parada

"Froth flotation is the most widely used mineral separation technique. It is based on the relative hydrophobicity of valuable and gangue particles. In a flotation tank, two distinct zones can be identified: the pulp and the froth. The pulp is a turbulent region in which hydrophobic valuable particles attach to air bubbles while hydrophilic gangue particles remain in the slurry. As the particle-laden bubbles rise, a mineralised froth zone is formed that overflows as a concentrate. Although the process is more than a hundred years old, there remain many aspects that are not completely understood, particularly for the froth zone. Thus, the rules governing the design of flotation tanks tend to focus on pulp zone parameters, which are largely based on operating data. An example of this is the design and operation of impellers. These tend to be designed paying attention to hydrodynamic phenomena in the pulp zone, but their effect on the froth zone has not been completely addressed. The role of impellers in a flotation tank is to break the air bubbles in order to generate smaller ones and to provide an environment that enables the collision between those bubbles and the particles in the slurry. This usually creates turbulent regimes that can affect the pulp-froth interface, destabilising the lower regions of the froth and affecting the overall performance of the process. Different impeller designs and retrofit modifications have been proposed in the past, addressing some of those issues. However, there is no systematic study of the effect of different impeller designs on the bubble size in the pulp and its links to the stability of the froth. This work tested the impact of an impeller designs combined with the use of a stator on the performance of an 87 litres continuously operated laboratory-scale flotation tank, with a focus on bubble size in the pulp and froth stability. The results showed that the implementation of a stator system decreased bubble size and increased froth stability. That resulted in an increase of mass pull, measured as a proxy of metallurgical recovery."

Jan 1, 2018

By Y. C. Liu

Ningxiang-type iron deposit is a most important sedimentary oolitic hematite deposit in China. Its? detected ore reserves are 3.72 billion tons, which is 73.5% of all detected reserves, and there are about 10 billion tons of prognostic resources. It is considered as the ?poor mine? for a long time be-cause of its difficult prooerty. But based on the ore characteristics of different deposits, the technological characteristics of ore are different with great diversity in ore baring horizon, distribution range, deposit scale, ore petrology, ore mineral assemblage and iron content. Through the study of deposit features and technological mineralogy of different Ningxiang-type of iron deposits in China, and based on industrial types and natural types of ore deposits, we divide different technological types according the technological features of the ore such as mineral composition, particle size, dissemination, occurrence of useful elements and harmful elements, the main physical and chemical properties of mineral and geological conditions of deposits, etc, moreover, propose the different utilization, mineral processing technologies and product schemes for the different types of ore.

Jan 1, 2014

By P. A. Bepswa

A numerical study done to test the efficacy of heuristics developed for the design of measurement networks for high precision metallurgical accounting is presented in this paper. The heuristics considered were designed to maximise variance reduction of terminal stream measurements through data reconciliation for observable linear flow systems. A complex metallurgical process flow sheet from the mineral sands industry was used as a case study. Monte Carlo type simulations coupled with a non-linear programming based steady state data reconciliation algorithm were used as tools to investigate the heuristics. The results obtained suggested a close correlation between magnitudes of measured variances and the respective levels of variance reduction obtained through data reconciliation for both internal and terminal streams. It was observed that variance reduction through data reconciliation was maximised for terminal stream measurements in networks characterised by high precision measurement of internal streams and/or in flow sheets characterised by high ?stream to node ratios?. Terminal streams attached to highly interconnected parent nodes were observed to experience higher reductions in variance compared to terminal streams attached to less interconnected parent nodes. The results generally highlight the additional benefits of highly interconnected flow sheets and high precision internal stream measurement regimes on the maximisation of variance reduction of terminal stream measurements through data reconciliation. These findings are significant to metallurgical accounting and to process accounting applications in general in that they provide a conceptual basis for design decision making regarding the construction of measurement networks aimed at maximising variance reduction of targeted streams through data reconciliation.

Jan 1, 2014

By H. Palza, C. Ihle, S. Contreras

"Processing of minerals, particularly treatment of tailings, has been increasingly challenged by the presence of clays in the feed of thickeners. This occurrence is expected to become increasingly important given the nature of ore deposits currently being exploited and those that have been recently discovered. In sedimentation operations (solid-liquid separation), industrial flocculants often fail to coagulate clay-containing fines, generating supernatants with high levels of turbidity, thus implying operational problems. Recently, it has been reported that graphene oxide (GO), a graphite derivative with high oxygen-containing groups, could enhance the flocculation of clay systems, due to the interaction between clays and GO functional groups. In the present work, we investigated the effect of doping industrial flocculants (commercial polyacrylamide) with GO on the floculation of kaolinite suspensions in a solid-liquid separation stage. Separation performance was evaluated by studying flocculation kinetics using a focused beam reflectance measurement (FBRM) instrument, in a set of batch tests. A statistical analysis of the flocculation kinetics and floc population distribution was further carried out. Our results suggest the existence of a synergistic effect between the studied flocculants and GO. This effect is observed as a decrease of clay fine contents in the supernatant, thus improving solid-liquid separation eficiency for high clay containing tailings. INTRODUCTION Copper, given its mechanical, physical and chemical characteristics, is a critical material for the progress of society and so has been from early stages of mankind. Demand for this metal has increased due to the growth of cities and the technological explosion, leading to increase current mining production and reinforce the efforts in exploration for new deposits (Elshkaki et al. 2016). As copper-rich deposits are being depleted, it has been necessary to develop proper technology to mine deposits of lower grades and more complex mineralogies, keeping in mind that the economic window that allows the exploitation of them is reduced by the increase on operating costs (Crowson 2012 and Northey et al. 2014). High clay bearing minerals are found in many of those low-grade copper deposits, and they induce problems in all stages of the mineral processing route (Taner and Onen 2016). Particularly, in the solid-liquid separation stage, the flocculation process fails to remove the clay fraction from suspension and it leads to operational issues such as filter damage, overconsumption of reagents and the need to add an extra clarifying step for the recovered process water. Those problematics pose an interesting challenge."

Jan 1, 2018

By M. Marinov

The Bulgarian deposits of quartz-kaolin raw materials are localized in the NE Bulgaria. For many years, the quartz-kaolin sand separation has been performing by water washing technology. After wet separation the raw material yields two products ? washed kaolin (different grades) and quartz sand (different grades). Research and development program has started to improve the quartz-kaolin sand separation. The program has undertaken an increasing of processing capacity, to decrease the losses in the tailings and to provide production of new quartz sand grades. The kaolin-silica raw materials from Vetovo open mine and the technological tailings from Vetovo processing plant were characterized. It was established that there are a lot of losses of quartz in final tailings. New approach on kaolin-silica raw material separation was tested in laboratory scale. The test work was performed on Derrick Stacksizer screening machines. The results of laboratory experiment show that there are possibilities to increase the quartz sand recovery and to start the production new grade sand. The full-scale pilot test was performed including the following units: two Derrick Stacksizer screening machines equipped with 0.430 mm and 0.150 mm opening Derrick Urethane Panel, respectively; Flat bottom DN 500 Hydrocyclone and DN 100 Hydrocyclon. The pilot test data clearly demonstrate that the Derrick Stacksizer screening machines are suitable for Bulgarian silica-kaolin raw material. Based on the test data a new quartz-kaolin separation technology was developed. The new technology was introduced in Vetovo processing plant increasing processing capacity and decreasing the losses of quartz in final tailings. Additionally the production of silica sand grade PK 0.16 is increased and starts the production a new grade PK 0.10.

Sep 1, 2012

By J. R. Cui

The production of electric and electronic equipment (EEE) is one of the fastest growing areas. This development has resulted in an increase of waste electric and electronic equipment (WEEE). In view of the environmental problems involved in the management of WEEE, many counties and organizations have drafted national legislation to improve the reuse, recycling and other forms of recovery of such wastes so as to reduce disposal. Recycling of WEEE is an important subject not only from the point of waste treatment but also from the recovery of valuable materials. Consumer electronic equipment (brown goods), such as television sets (TV), radio sets, and video recorders, are most common. However, recent work on recycling of waste electric and electronic equipment (WEEE) primarily focused on personal computer and printed circuit boards scraps. Based on a detailed characterization study of consumer electronic scraps, recycling of TV scraps oriented to recovery of metals is highlighted by utilizing air table separation, eddy current separation, and optical (metal) sorting process. The result indicates that a high recovery of copper could be obtained by utilizing an effective gravity separation process. The separation results reveal that air table separation is an effective technology to recover metals from consumer electronic scraps. By using a DGS table, approximately 90% of non-ferrous metals were recovered in the heavy product with a purity of 40%. Printed circuit boards and cables in TV scrap cause metals loss due to the fact that metals in printed circuit boards and cables are not liberated from plastics and ceramic materials. The study shows that eddy current separation and optical (metal) sorting process provide alternatives for recovery of metals from shredded TV scraps.

Jan 1, 2014

By Milind Chikhale, Yogesh Reja, Keshav Tyagi

"Using computer models for process design is a well-established practice in the mineral industry. In recent years, there has been emphasis on modeling of processing plant as a whole. This paper covers development of a model for iron ore processing plant. Basic purpose of this model is to use simulation for efficient plant design and help in minimizing risk at the very initial stage of project. Feed to the plant is Hematite iron ore from a deposit located in Eastern India. Major processes in plant include multi-stage crushing, screening, grinding, classification, gravity and magnetic separation. Models for different process equipment were developed using METSIM and Bruno simulation software. Customized black box models and known mathematical models were used for predicting behaviour of processes. Data needed was identified based on the model type. The required data was arranged as per project requirement and processed for development and validation of model. Equipment models were developed and validated on the basis of process design basis, theoretical and empirical data from technical references, and bench scale and pilot scale testwork results. Validated process circuits were assembled to simulate and represent the entire plant process. The result shows expected variation in plant output as a result of variation in the feed. Study concludes by discussing potential applications of the model in plant design."

Jan 1, 2014

By R. Singh

The present paper deals with the development of flotation based process for enrichment of a lead-zinc sulphide ore from Ganesh-Himal region of Nepal. Detailed characterisation and flotation studies were carried out under varying process conditions. The sample assayed 2.47% Pb with 13.6% Zn. The ore was predominantly made up of spahlerite and pyrite in association with subordinate amounts of galena, minor amounts of pyrrhotite and chalcopyrite. Dolomite was the main gangue. The modal analysis showed the probability of fair liberation of sulphides from gangues around 210 microns but the locking of galena with sphalerite and other sulphides continued to finer sizes. Under the optimum process conditions the rougher lead and zinc recoveries were 96.3% and 90% respectively. Multistage cleanings of rougher products proved helpful in improving the concentrate grade, meeting the required specification. Based on the studies undertake a process flow-sheet for the concentration of the ore to individual lead and zinc concentrates was developed.

Jan 1, 2014

By Sudarshan Martins, Peter Radziszewski

"Tumbling mills are machine, operating in non-equilibrium, capable of applying forces on the ore contained within, causing the ore to break down. The action of the mill on the ore is very inefficient, producing a large quantity of heat. The inefficiencies of the mill drive the desire for improvement, spawning research and development activities. Given the non-equilibrium nature of the mill, the theory of Large Deviations is proposed as the framework that captures the state of the mill. The theory of Large Deviations allows for the determination of the rate function and the scaled cumulant generating function (SCGF), for systems in either equilibrium or non-equilibrium. Powerful connections can been made between familiar concepts of statistical physics and the concepts introduced by the theory of Large Deviations: entropy can be associated with the rate function; the scaled cumulant generating function with the free energy. It is shown that observables, compatible with Large Deviation theory, can be identified for the tumbling mill. Here, the time series of the energy associated with an element of the charge is such an observable. Furthermore, using some experimental data, it is shown that the time series of the energy can define a rate function, thereby describing the system within the Large Deviation framework. Finally, a discussion of the results is given, particularly how this theory can be further developed for tumbling mills."

Jan 1, 2014

By K. Takahashi

Generally speaking, wastewater coming from the metallurgical process for recovering precious metal contains precious metals such as gold (Au), platinum (Pt), palladium (Pd), Silver (Ag), etc., which concentration is about 10 mg/L. In addition, there are other metals such as copper (Cu), iron (Fe), which concentration varies from several mg/L to more than 10,000 mg/L. It should be noted that the concentration of metals in wastewater is relatively high, considering the fact that these metals of similar concentration can be found in ores. However, most of these valuable metals are not treated, due to the high processing cost and technical problems. Within this frame, the authors put forward a new process that includes neutralization/reduction, precipitation and fusion. The idea is to recover and recycle Au, Ag, and Pd metals as well as protecting the environment by saving the resources. It was found that this new process was able to recover more than 90% of Au, Ag and Pd.

Jan 1, 2014

By Anuj Narang

Large-scale separation or flotation cells, used in the primary extraction in the oil sands industry, are integral parts of the overall process of bitumen extraction. Good regulation of the interface level between the bitumen froth and the middlings in these cells can result in a significant improvement in bitumen recovery and throughput, and heavily influence process economics. Automatic control of such industrial processes presents challenges such as multi-phase flow dynamics, variable process gain and time delays, poor quality of measurements and significant disturbances. This paper details a case study application of development of multiple models of the dynamics of the interface level and the design of model predictive controllers (MPC) for a separation cell process. A Model predictive controller (MPC) using linear models is designed and implemented in real time on an industrial separation cell. The industrial implementation results show that the MPC scheme provides significant benefits over the current operations which use a PID controller. The benefits include significant reduction in the variance of the interface level resulting in higher bitumen recovery and smoother downstream operation plus energy savings due to reduced underflow pump speed.

Sep 1, 2012

By Johannes Käppeler, Alexander Weh, Harald Giese, Klaas van der Wielen

"High voltage breakage is a novel comminution technology that shows considerable potential for various applications in mineral processing and recycling. It relies on highly energetic electrical pulses to induce electrical explosions in rocks, causing the formation of plasma channels and powerful shockwaves that result in fracturing and fragmentation of particles. There has been considerable interest in this technology for its ability to weaken rocks and preferentially liberate target minerals, as previously demonstrated by other authors. Weakening has the potential to significantly reduce energy consumption during comminution, or alternatively, increase throughput of a circuit. Better liberation may yield an improved concentrate grade and/or recovery, reduce fines losses to tailings or increase the grind size required for liberation, thereby also reducing energy requirements. This review aims to increase general awareness of this technology, and promote further research into it by providing a general summary of the theory underlying high voltage breakage, as well as the envisaged applications of this novel technology. A brief history of the technology is presented before progressing onto the physics underlying the electrical and geomechanical aspects of high voltage breakage. Key results regarding weakening and liberation are discussed, and some mention is made of current challenges and planned developments to increase the throughput of high voltage breakage units to the level where it can be integrated into new and existing processing circuits."

Jan 1, 2014