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By Janne Kytökari

Controlling a wide range of minerals processes with single control system is an ordinary way to operate in mines all over the world these days. However the potential of these systems is not yet fully recognized nor utilized. The key issue is to manage the information in a way that enables automating the day-to-day tasks, quality control and safety functions. At the same time it provides means for optimization and constant improvement of processes creating a working environment where the system helps employees to do their key tasks instead of searching, modifying, and transmitting the huge number of information arising every day. The distribution of control system nodes enables the other processes to run heedless of a problem occurring in one of the sub-processes. Also the control room can be in remote location such as in large city removing the need to travel substantially long distances to plant sites every day. When all essential information is brought to the same place there is less risk for a mishap to happen due to information breaks that are often the cause of them. One of the biggest single reasons that result in production losses are break downs of machinery usually caused by normal wear, misuse, incorrect utilization rate etc. For this reason it is important to measure the condition of machines using vibration measurement and diagnostics. By moving from failure or time-based maintenance towards predictive or performance maintenance generates eventually a steady and predictable process but also results in significant long term savings. The mineral process at Talvivaara mine is based on bioheapleaching, whereby metals are leached from ore as a result of bacterial action. Bioleaching is a fairly new technology used in metals recovery. Therefore it is important for the mine to collect and analyze data from different stages of the minerals process. Talvivaara mine?s Metso DNA system has integrated machine condition monitoring and information management. These are not only necessary but also crucial in environmental conditions where the outside temperature can drop below -35°C, where ice and snow dominate the landscape and impact the equipment for four months a year and where distances between equipment can be up to 7.5 kilometers. Keywords: DCS, analyzer, machine condition monitoring, automation, remote communications, optimization, mining, metso DNA, Talvivaara

Sep 1, 2012

By M. K. G. Vermaak

Kimberlite weathering has been a topic of ongoing research within De Beers for many years. Using kimberlite weathering as an alternative to crushing has many advantages e.g. power and reducing diamond breakage. Weathering could also possibly be used in conjunction with crushing just to weaken the material and reduce power consumption. These forces have driven current research to investigate whether kimberlite weathering could be utilised for these reasons. Weathering in this context does not refer to weathering over long period of time but rather to disintegration of the material in aqeous media in relative short time periods. Previous published work discussed that the presence of smectite renders kimberlite weatherable and that the amount of smectite determines the rate of weathering (Morkel and Vermaak, 2006). The current work investigates whether cation ex-change or the adsorption of organic species in the smectite interlayer could influence the observed weathering behaviour. The results show that cation exchange does take place in the presence of cation species and that the weathering behaviour can be drastically improved with especially Cu2+ cations. Concentration and time effects of the weathering was also investigated. Weathering tests with organic species such as ethanol, methanol, edta, pentanol, butanol, acetic acid and oxalic acid was performed. The results show that organic species does improve weathering but under these testing conditions was not as effective as cations.

Jan 1, 2014

By Q. Zhang

The flotation behavior of jamesonite was investigated with ethyl xanthate as a collector. It has been shown that jamesonite has good floatability from pH 2 to pH 12, and relatively poor floata-bility at pH>12. The flotation of jamesonite was also dependent on pulp potential at certain pH val-ues. The potential-pH range for jamesonite flotation was established. The FTIR spectroscopy analy-sis and XPS measurement showed that the major adsorption product of ethyl xanthate on jamesonite was lead ethyl xanthate and antimony ethyl xanthate. The intensity of the FTIR signals of metal ethyl xanthate adsorbed on jamesonite and the flotation response of jamesonite were correlated with pulp potentials.

Jan 1, 2014

By Xiaoping Xu

An albitization granite type tantalum-niobium ore from Jiangxi Province, China was taken as the research object in this paper. The main valuable minerals in this ore are tantalite-columbite and uranmicrolite, and the minerals that can be comprehensively recovered include cassiterite, sulfide minerals, topaz, zinnwaldite, and quartz-feldspar. Based on the research results of process mineralogy, the roughing process of gravity separation for coarse particles combined with flotation for fine particles is proposed. The combined cleaning process of flotation-gravity-magnetic-electric-hydrometallurgical separation is adopted for the rough concentrate of gravity separation while the combined cleaning process of gravity-flotation- hydrometallurgical separation is adopted for the rough concentrate of flotation. High intensity magnetic separation is used to separate and recover zinnwaldite and quartz-feldspar from gravity tailings. By mineral processing for the crude ore containing (TaNb)cassiterite concentrate is 0.0003% with a grade of Sn 63.22% and a recovery of Sn 47.42% while the yield of sulfide concentrate is 0.0783% with a grade of Pb 33.15% and Zn 27.09% which can be separated to get lead and zinc concentrate respectively. The yield of topaz concentrate is 0.1545% and the topaz mainly distributed in the size range of -0.4+0.074mm, which can be made into abrasive products of different particle sizes after classification. The yield of zinnwaldite concentrate is 16.91% with a grade of Liwhiteness of 75%, which is a glass-ceramic material of good quality. 2O5 0.0346%, Sn 0.04%, Pb 0.10% and Zn 0.33%, the tantalum-niobium concentrate with a yield of 0.00278%,a grade of (TaNb)2O5 53.61% and a recovery of (TaNb)2O5 44.49% is obtained. And the yield of 2O 1.34% and Rb2O 0.40%. The yield of quartz-feldspar concentrate is 30.42% with a grade of K2O+Na2O 8.98% and Fe2O3 0.11% and a natural All of tantalum, niobium, cassiterite, topaz, zinnwaldite, quartz, and feldspar are recovered effectively. Keywords: tantalum-niobium ore, gravity separation for coarse particles, flotation for fine particles, comprehensive recovery

Sep 1, 2012

By Ali Dehghani Ahmadabadi

Gravity separation technique is widely used in mineral beneficiation practices for its low cost, ease of operation, and eco-friendly nature. The most commonly used gravity methods for beneficiation of iron ores are shaking table, jig and spiral methods which aren't very effective for iron mineral fines. Multi-Gravity Separator (MGS) is suitable for the treatment of fines with a maximum particle size of approximately 500 µm. This study was performed on a low-grade haematite iron ore from Chadormalutailing dams. Detailed mineralogical, physical and chemical characteristics of a goethiticlateritic iron ore showed that the sample contained porous and friable oxides and hydroxides of iron. The ore sample had a feed grade of 35% Fe, 1.1% FeO, 15.5% SiO2 and 8.5% Al2O3. Haematite and goethite are the main iron-bearing minerals while quartzite and kaolinite are the major gangue mineral constituents. In this paper, the statistical evaluation and optimization of grade and recovery using a factorial design of experiment (DOE) method has been carried out for Chadormalulow grade ultra-fine haematite tailings with MGS. The input process parameters considered are drum speed, tilt angle, wash water flow rate and pulp density. The results show considerable improvements in both the quality characteristics such as grade and recovery with statistical evaluation and optimization, compared to the initial value of grade and recovery. Keywords: multi-gravity separator, mgs, statistical evaluation, optimization, haematite

Sep 1, 2012

By V. M. Mankov, O. V. Zamyatin

"Fine free gold at a size of minus 250-100 µm can be effectively recovered from mineral materials (buried clay placers, saprolites, gold-bearing aggregates, technogenic sands etc.), or MM, using some developed and implemented in practice cost-effective basic technological schemes of MM processing at every stage: exploration, main concentration processes, upgrading of gravity concentrates etc. Such technologies are based on mineral materials composition, different content of fine gold mass fractions, and include improved two-stage sluicing technology, jigging technology, advanced technology and integrated technology. The main operation principle of the given technologies is gravity concentration. They provide recovery of fine gold of any size from MM, including gold finer than 100 µm, using concentration systems and plants with a capacity of 1-2 and up to 100-200 m3 per hour. Selection of a cost-effective technology depends on its technical and economic viability regarding to mineral material composition, optimum performance and concentration rate. The developed technologies of mineral materials concentration establish a balance between technological, technical and economic factors, and ensure profitable development of deposits containing free gold and characterized by a complex composition of concentrating material. Free gold recovery with these systems increases by 2.0-2.5 times for gold particles at a size of minus 250+100 µm and 10-30 times for gold particles of minus 100 µm, compared to conventional sluicing systems. The Irgiredmet Institute has developed and supplies primary concentrate washing machines for upgrading gravity concentrates of up to 100 mm in size, with a capacity of 1.0-5.0 m3/h, fitted with various production equipment including pyro- and hydrometallurgical systems. Additionally, the Irgiredmet Institute develops and manufactures systems of mechanized processing of geological and technological samples (UOMP; registered design certificate No.27505, Russia) designed for complete recovery of free gold in the process of geological samples handling and decreasing of a human factor influence. A system includes a package of technologically associated disintegration, classification and concentration equipment with some “know-how” elements that provide effective recovery of fine gold at the exploration stage. A number of Irgiredmet’s patented technologies and systems (patents of the Russian Federation) have no equivalents in the field of mineral processing and provide designing of technologically practical and cost-effective flowsheets that offer higher recovery of gold of different sizes (fine gold), at every stage of processing of mineral materials including basic concentration processes, upgrading and exploration etc."

Jan 1, 2018

By W. Y. Liu

A sulfate reducing bacteria strain (named SRB-A) is isolated from sanitary wastewater by using anaerobic technology of Hungate. The studies of physiological, biochemical and phylogenic of the isolated strain are carried out. The colonies of the strain are circle. Cells that are slightly curve, rod-shaped with the size of 1.0~3.0µm in length and 0.8~1.0µm in width. The optimum temperature for growth of the organism is 30~35°C. The optimum pH for growth is 7.0~7.2. Strain SRB-A can use sodium lactate, sodium citrate, sodium acetate, ethanol and acetone as electronic acceptor but can not use glycerol, glucose, sucrose and sodium oxatate. The isolated strain reduces sulfate, sulfide, sulfur, DSMO and FeCl3, then nitrate and nitrite can not be used. The strain has higher tolerance of NaCl, and the optimum growth occurs in the presence of 5%~8% (w/v) NaCl. The result of 16S rDNA sequence analysis indicates that the isolated strain SRB-A is the most similar to Desulfo-vibrio halophilus, and the level of the similarity was 98.4%. The isolated strain has a stronger ability to reduce sulfate, and the level of sulfate reduction reaches about 90% at pH 7 in the liquid medium. 0.6 to 0.8 is the optimum COD/SO42- in the medium for the isolated strain to show better ability to reduce sulfate. At pH 2.5 the level of removal of Cu2+ reaches 96.3%. Under the condition of pH 3.5, the level of removal of Zn2+ reaches 92.6%. When the value of pH reaches about 7, the Fe3+ is precipitated by the formation of Fe(OH)3, and Fe3+ is removed up to 89.4% at last.

Jan 1, 2014

By Abhakumari

Effect of applied DC potentials on the bioleaching of a chalcopyrite concentrate in the presence of Acidithiobacillus ferrooxidans is discussed. Copper dissolution was the highest at an applied potential of +600mV (SCE), while all the dissolved copper got cathodically deposited at a negative potential of -600mV (SCE). Electrobioleaching at an applied potential of +600mV (SCE) was established at different pulp densities as a function of time. Effect of the magnitude of electrolytic currents on the activity and growth of bacterial cells was studied. Preadaptation of bacterial cells to the concentrate slurry and electrolytic growth conditions significantly enhanced copper dissolution. Electrochemical and biochemical mechanisms involved in electrobioleaching are illustrated with respect to oxidative dissolution and bio catalysis of anodic oxidation.

Sep 1, 2012

The molybdenum ores currently utilized in China are mostly molybdenum sulfide ores whereas oxidized molybdenum ores, being finely disseminated and difficult to process, have not been exploited and utilized effectively. In this article the beneficiation process of a molybdenum ore occurred in an oxidized ore zone was investigated in order to provide a new way for the development and utilization of the oxidized molybdenum ores in China. The molybdenum mineral in the ore was mainly wulfenite and the associated minerals included barite, limonite, quartz and small amount of cerusite. Limonite in the ore occurred in a crust and honeycomb-like colloidal state and composed the framework for the formation of the other minerals in the ore, which filled the pores in the framework. Wulfenite was mainly fine-grained and occurred in the fine porous crust and honeycomb-like framework. The finely disseminated ore structure made the separation and recovery of the molybdenum mineral in the ore very difficult. On the basis of the mineralogical study of the ore, experiments were conducted to compare the various mineral processing methods for the beneficiation of the ore, including single gravity concentration, single magnetic separation, single flotation, and a combination of high intensity magnetic separation and gravity concentration. The results indicated that with single gravity concentration a molybdenum concentrate containing 5.85 % Mo with a yield of 11.76 % and a Mo recovery of 43.5 % was produced. With single high intensity magnetic separation it was very hard to obtain a molybdenum concentrate product. With single flotation process a molybdenum concentrate containing 7.06 % Mo with a yield of 15.14 % and a Mo recovery of 62.63 % was produced. With a combination of high intensity magnetic separation and gravity concentration a molybdenum concentrate containing 6.46 % Mo with a yield of 11.81 % and a Mo recovery of 42.11 % was produced. In conclusion, compared to the other methods the flotation process can produce more reasonable technological and economical results and is the best process for the exploitation and utilization of the finely disseminated oxidized molybdenum ore.

Jan 1, 2014

By A. Pandey

Over the years, Coal Beneficiation at Tata Steel - West Bokaro has seen varied changes. With increasing R.O.M throughputs & lowering of the concentrate ash, Fine Coal Beneficiation process has thrown up myriad challenges. Development of Synthetic Collector was initiated couple of years back with Technical assistance from NLC Nalco India Ltd. Coal from West Bokaro unit was sent to Nalco?s Naperville (US) research lab for developing Tailor made synthetic collector . After comprehensive lab flotation studies, synthetic collector was developed & recommended for plant evaluation. The lab scale results were very promising in terms of improved separation efficiency & yield at similar ash level. The collector sample received from Nalco research laboratory were revalidated at Nalco Kolkata lab and finally at Tata Steel West Bokaro lab, confirming the promising results. (S.E 25-30 % better than HS Diesel) The key factors playing out for this improvement initiative are a) Scope for improvement in Clean Coal Yield at same or lower ash level coupled with improved Selectivity and Separation Efficiency b) Introduction of a Synthetic Collector with a Green Chemistry and subsequent replacement of H S Diesel, which is highly inflammable with a less inflammable & safer product Trial was conducted at plant scale in two phases and comparative performance of the Collector vis-à-vis Diesel was evaluated across the following Coal Seams of Q- SE (Seam VII, VIII, VI, IX and X). The results generated are very promising and the improvements observed are summarized below. ? Separation efficiency improvement by more than 20% observed. ? Flotation Fines yield increase varied from 0.6- 1.5 % on raw coal basis across different seams. ? Consumption pattern is 20-25 % lower than Diesel. Keywords: synthetic collector, west bokaro, coal beneficiation, HSD

Sep 1, 2012

By K. B. Venkatesh

In view of the importance of size reduction operations from the energy consumption point of view, during the past one hundred and fifty years a number of attempts have been made to develop a general energy-size relationship. However, to date it has not been possible to clearly define the scope of application of various laws proposed, though Bond law has been widely used with a moderate degree of success. It was, therefore, decided to carry out a thorough analysis of the batch ball mill grinding data available in the literature on several minerals that were ground under normal range of operating conditions. In particular, relationships proposed by Bond, Kapur, Voller and Morrell were examined in detail. It was found that the relationship proposed by Kapur in terms of the mean particle size provided a more accurate basis for estimation of energy. The value of the exponent of mean particle size in this relationship, a, is same as the exponent of the particle size in the expression for the grinding rate parameter: ki = Axia, provided the particle size distribution range corresponds to the self-similar or self-preserving regime. In this regime, mean particle size is proportional to the 80 percent passing size and size modulus. From the practical application point of view, it was possible to describe the variation of µ1 over limited, but significantly broad size range, using a constant value of a. Thus, by carrying out a few batches, grinding experiments over the size distribution range corresponding to the contents of the production mill, the applicable value of a can be determined. Keywords: energy-size relationship, ball mill, mean particle size, self-similar size distribution regime

Sep 1, 2012

By S. Liu

With the development of global economy, the demand of mineral?s quantity and quality are in-creased, valuable minerals are more and more finer and poorer, and the capacity of concentration plant are more and more high. Using large-scale flotation cells can obviously enhance the capacity of treating the mineral, reduce the cost, and increase the economic benefit and competitive ability for the enterprise. BGRIMM advanced advisable technical scheme with optimally parameter and route for the feature of dynamic in large scale flotation machine, and developed the KYF Large Scale Flotation Cells, which have used more than 400. The paper advanced the history, the design principle, the operating principle, the structure feature and the application of KYF flotation ma-chine.

Jan 1, 2014

By N. Pradhan

In the Sukinda valley, Orissa, India, a large quantity of overburden material is generated during the mining of chromite mineral (on average 10 tons for every ton of ore). The overburden hereby depicted as ?lateritic nickel ore? contains on an average 0.5% Ni. IMMT Bhubaneswar is working on this material for extraction of nickel and cobalt. But for better recovery of metal values, thermal activation or thermal reduction of ore is required. An alternative biotechnological route for reduction of ore is hereby attempted. An anaerobic dissimilatory Iron (III) reducing bacterial consortium (here denoted as IRB), capable of imparting iron phase changes in the lateritic nickel ore was established which improves the subsequent extraction of co-precipitated Co (III) and Ni (II) from the ore. In this study, properties of thermally and microbially reduced lateritic nickel ore are compared vis-à-vis original ore. Due to the phase changes, original light brown color of the lateritic nickel ore changes to dark brown on IRB treatment. This dissimilatory reduction of ore leads to formation of some magnetic particles, which were separable by hand held magnet. Roasting and IRB treated ore on acid leaching with H2SO4 show about 45 % and 36 % leaching of nickel ore compared to about 18 % leaching from the original lateritic ore. If bacterial reduction method is successful, cost intensive method of ore roasting process can be eliminated. Thus, it is possible to make use of dissimilatory iron reducing bacteria for recovery of valuable metals from off grade iron ore/ laterites. Keywords: lateritic nickel ore, bacterial reduction, thermal reduction, dissimilatory fe (iii) reducing bacteria

Sep 1, 2012

By S. Gaydardzhiev

Initial experiments towards preparation of hollow ceramic microtubes by dip-coating of fibrous plants with water based alumina gel-casting slurries using hemp and coconut fibres as templates have been done. It has been found that the wettability of fibres and accordingly the stability of the developed ceramic layer on their surface during slurry gelation varied significantly within the different fibre types. Good correlation between the diameters of the template fibres and the resulting channels has been found at the level of solids loadings used, 31 %. Hemp fibres used as bundles have led to formation of multi channel patterns while the coconut fibres-templated process resulted in uniform monochannel materials. The micro tubes have show good mechanical handling.

Jan 1, 2014

The simulation study on the process of iron ore beneficiation plant of Essar Steel, Kirandul was carried out. The iron ore fines and slimes generated nearby Bailadila mines of NMDC are used as raw materials for this beneficiation plant. The capacity of the plant is 1400 TPH operating in parallel in two streams. The capacity of the plant was utilized about 60% of throughput capacity. To improve the plant capacity as well as quality performance, the simulation study was conducted to detect the bottleneck of the process. The process samples were collected from input and output of each processing unit operation to generate the data base for simulation study at the feed rate of 400 and 500 TPH of iron ore fines in a single stream. The characteristics data i.e., breakage and selection functions were generated using MILLSOFT package for simulation of ball mills. Then MODSIM package was used to evaluate the performance of each unit operation to identify the bottleneck. It was established by a simulation study that the intermediate thickener draws high current when the feed rate is more than 400 TPH due to high torque drawn by rotating rake because of presence of coarse particles in the input stream to thickener. The problem was sorted out by classification of input stream of thickener to remove the coarse particles. Then the process was simulated at its rated capacity, and experimental validation studies at the plant were also conducted at the feed capacity of 600 and 700 TPH by modification of process flowsheet. The experimental data was almost matching with simulated data. Finally, the processing plant is running with full rated capacity without any bottleneck. Keywords: simulation of ball mill, breakage function, selection function, iron ore

Sep 1, 2012

By V. A. Chanturiya

There is an obvious disproportion in Russia gold-mining industry between the structure of gold reserves and the gold-mining techniques. The bulk of gold (over 70%) is extracted from alluvial deposit, 20%~25% from bedrock occurrences and 5%~7% from complex copper-zinc and polymetallic ores. The proved gold-bearing reserves are distributed as follows: alluvial ?19%, bedrock ?80%, the latter being sufficient to supply gold at the current production level for 100 years to come. In Russia, like elsewhere in the world, development of primary gold deposits is considered a first-priority line of development for gold-mining industry. Most of the gold-containing ores characteristic of Russian gold deposits are resistant ores with gold content varying between 3 ppm and 5 ppm usually showing quite low gold and silver recovery by cyanidation. Processing resistance of gold-containing mineral complexes is related to the presence of gold particles of submicrometric (<1.0 µm) and nanometric (10~100 nm) size, mostly asso-ciated with pyrite and arsenopyrite. Therefore switching over to processing bedrock entails a num-ber of technological problems that stem from chemical and physical resistivity of ores. The chemical resistivity can be overcome through flotation, oxidation roasting, autoclave leaching (biohydro-metallurgical oxidation), etc. The physical resistivity can be dealt with by resorting to traditional power-intensive methods,e.g. grinding to a ?40µm size, thermal treatments of sulphide concentrates and non-traditional high-energy methods of liberating the sulphides by means of power attack, e.g. electro-chemical oxidation, exposure to electron beam radiation and other methods. The modern non-traditional processes for treatment of rebellious noble metal-bearing ore, aimed at improving disintegration efficiency for finely dispersed mineral complexes are analysed. Advantages and perspectives of a new high-efficient, energy-saving and ecologically safe process of the nanosecond high-power electromagnetic pulses (HPEMP) effect are proved. The said process provides a stable increase in the valuable component recovery at lower energy consumption and production costs of the finite product at the stage of dressing rebellious gold-bearing ores and concentrated products. The experimental data prove high efficiency of the preliminary impulse treatment, thus, the increase in the gold recovery at the cyanidation stage amounted to 4%~12% from rebel-lious ores, 10%~30% from gravity concentrates, 5%~45% from flotation concentrates, 30%~80% from oil flotation tailings.

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 V. F. Bannikov, A. P. Kozlov

"The purpose of this study was to develop a theoretical and technology framework for designing new combined technologies for processing tailings containing non-ferrous and noble metals using dry separation. The main goals of the study were: identifying the distribution patterns of valuable components in various fractions in dry separation processes; examining the patterns identified for different types of non-ferrous and noble metal tailings; developing a theoretical and technology foundation for the development of innovative technologies for the efficient processing of tailings with minimal process water consumption. To examine the possibility of efficient recovery of valuable components from refractory tailings using dry separation, an experimental laboratory unit was designed and built, composed of novel or modified lab equipment: plasma unit for increasing the magnetic susceptibility of Fe - containing minerals; magnetic separator supporting isodynamic and polygradient fields; pneumatic separator for the dry separation of finely dispersed mineral mixtures; dielectric separator using the resonant frequency of the electric field. The laboratory unit supports various modifications and combinations of the lab equipment. The experimental studies led to the development of a unified process scheme for lab tests of mature and non-ferrous smelter tailings using dry separation methods.INTRODUCTION The huge amount of waste from mining and processing of mineral resources Russia inherited from the extensive use of mineral resources in the Soviet Union and amount of waste continue to grow. Often the content of valuable non - ferrous, rare and noble metals in waste exceeds the balance contents in natural ores of the developed deposits. The availability of a rich scientific reserve for the creation highly effective innovative technologies for waste processing determines the necessity of the acceleration in the resolution of problems of the complex assessment, capitalization and involvement in the processing of technogenic resources in Russia (Chanturiya and Kozlov, 2014.)."

Jan 1, 2018

By Vasile Murariu, William Pate, John Herbst, Dilek Alkac

"Multiphysics models are essentially first principles models capable of providing very accurate micro scale predictions. The computational requirements for Multiphysics Models are extensive, precluding their direct use for flowsheet simulations. Population balance models get their form from theory but the model parameters have to be provided from experiments. The prediction errors for the population balance models are typically significantly higher than those for the Multiphysics Models but the computational effort for Population Balance Models is typically much less than that for the Multiphysics models. The hybrid model described here takes advantage of the strengths of each of the two primary model types and minimizing the weaknesses of each. The Multiphysics Model is used to perform high accuracy "experiments" that are difficult or impossible to conduct in laboratories or plants. The results of these experiments are combined with standard laboratory or plant data to parameterize and further enhance the Population Balance portion of the hybrid model. The creation of a useful Hybrid Model is demonstrated for a MP1000 secondary crusher. The validation of the hybrid crusher model is also presented. Finally the use of the Hybrid Model is illustrated in a full comminution flowsheet simulator."

Jan 1, 2014

By A. A. Remes

High precision on-line particle size distribution measurement of mineral slurries has recently be-come available. It provides new tools for the development of monitoring and optimization methods for mineral grinding and separation circuits. The paper presents the development work at the Kemi chromite concentrator plant of Outokumpu Tornio Works in Northern Finland. The Kemi concentrator processes annually 1.2 Mt of chromium ore. The products are upgraded lumpy ore and metallurgical grade concentrate. The concentrate is produced using gravity separation methods, preceded by a rod mill - ball mill grinding stage. The separation process performance is strongly dependent on the particle size distribution of the grinding product at the Kemi plant. Particle size distribution has a significant effect on the concentrate grade and recovery. Currently a new laser diffraction based on-line particle size analyser is used for monitoring the grinding product. The analyser system allows the measurement of the whole cumulative particle size distribution simultaneously. It provides a wealth of new measurement information for process control. A monitoring and optimization scheme for grinding and gravity separation based on the particle size information is presented. The goal is to minimize the production of fine slime, and subsequently to improve the concentrate quality and minimize chromite recovery losses. Data-based recursively identified linear PLS process models are developed for optimization purposes. The preliminary results of the monitoring system operation in on-line use are presented.

Jan 1, 2014