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By S. Banisi, A. Haji-Zadeh, H. Asadi, M. Maleki-Moghaddam

One area in AG/SAG milling field which has received a great attention is the optimization of liner design for any application to increase the availability of mills. The Gol-E-Gohar iron ore concentration plant uses three 9m × 2.05m autogenous mills (AG) in parallel in a dry operation. The AG mill shell is lined with three series (57 cm each) of 36-row liners. Due to large variations in feed characteristics and inadequate blending, the performance of AG mills has been lower than the target value. Therefore, to improve the comminution efficiency, the optimization of the design of AG mill shell liners was applied in this plant. By simulation it was found that increasing the liner lifter face angle from 7 to 30° while maintaining the original lifter height (i.e., 22.5 cm) could provide an appropriate charge trajectory. Measurement of the wear profiles of shell liners indicated that the wear along the liner length was not uniform and the highest wear occurred between 0.5 m and 1.2 m of the mill length. A new liner design was proposed by redistributing the metal from parts with a lower wear rate to the parts with a higher wear rate to arrive at a uniform wear profile along the liner length at the liner removal time. The non-uniform shell liner was constructed and installed in one of the three parallel dry AG mills. It was found that the first and second liner designs increased the mill throughput by 2.6 and 7.5%, respectively. After conversion to SAG milling on the account of liner change, 18% (from 413 to 489 t/h) increase in throughput was realized. It was predicted that the non-uniform liner designs will increase the liner life time by 10% and will reduce the scrap metal from the current value of 59% to 50%.

Jan 1, 2014

By E. Alldén Öberg

In 2004, LKAB decided to start a basic engineering study in expanding its existing production lines at the Malmberget mine site. It was expected that some of the production lines would become bottlenecks with reference to capacity. In this study, the sorting plant is examined and the results show that several unit operations will be limiting under current operating conditions. An additional purpose with the study was to investigate how replacement of some machines would influence performance and if production plans for the coming years might be achieved. Steady-state simulations using the software Modsim? were extensively used to study process performance for different operating conditions, such as iron content and size distribution in run-of-mine ore. Model parameters were derived from pilot plant data and when possible from ex-isting circuits. A complication for the simulations was the lack of relevant data and therefore some of the initial results were only indicative. The result shows that installation of new screens would give a much better operation, but also new crushers would be an improvement. This, since they can be run with full crusher chamber and tighter CSS. During 2007, most of the proposed remedies were implemented and the result is that the bottle-necks are gone, and the grades and material balances are even better than what was envisioned from the simulations.

Jan 1, 2014

By M. Chettibi

The interaction and galena flotation with xanthenes and dexanthogen regularities have been de-fined. So, using thermodynamic method of analysis, the thermodynamic stability of [galena - xanthenes - water] system and the behavior of lead xanthenes surface state in solution were devised. Thus, results of cared out calculations and experimental investigation completely coincide with-out depending on witch product of sulfur oxidation is formed in the solution. In additional, was obtained quantitative physico-chemical models for the necessary xanthenes concentration of lead sul-fide complete flotation in the tuning fork of: at ?? values from 7.0 up to 9.0 (or at the formation of lead carbonate PbCO3 ) and at ?? values from 9.0 up to 12 (or at the formation of lead hydro carbonate Pb3(OH)2(CO3)2 Physico-chemical models derived can be used as the criteria for functional units of automation systems to control and regulate the flotation process in mineral processing plants.

Jan 1, 2014

By Paulo Castillo, Cesar Gomez, Jaime Alvarez

Operations using flotation to produce mineral concentrates require testing of frothers to characterize their ability to preserve bubble formation size and to build a stable froth. Many techniques have been proposed to measure parameters associated with these two roles. These techniques focus, in general, on only one of these roles and are based on special equipment operated at conditions quite different from those existing in industrial cells and columns. Both roles have been simultaneously characterized in a laboratory flotation column, but the requirements associated with the installation and operation of one of these units, are a serious limitation for its use on-site. A technique based on the use of a laboratory mechanical cell, a common piece of equipment in operations, will have wider application. Establishing the ability of a frother to control coalescence by preserving bubble formation size is done through bubble size measurements as a function of frother concentration. Froth build-up and stabilization is associated with the amount of water carried by bubbles into the froth layer, which has been demonstrated to correlate with the gas holdup in the collection zone. Procedures devised for determining the critical coalescence concentration (CCC) from measurements of bubble size as a function of frother concentration, and the gas holdup by collection of water displaced from the cell by the presence of bubbles at different frother concentrations, were tested. Three analytical-grade frothers were utilized: a straight-chain (1-heptanol) and a branched (MIBC) alcohol and a polyglycol (PPG425). The results obtained at a standard set of conditions, demonstrated consistent differences between these frothers, and the ranking from least to most effective for reducing bubble size or decreasing water drainage followed the same sequences found when more complex frother characterization techniques are used.

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 L. M. Sun

Baotou Baiyunerbo Mines Location in Inner Mongolia is a famous deposit of iron mineral and rare earth mineral accreting. The iron ore has very complicated ingredients and minerals composing. In the mine, there is not only magnetite ore but also hematite ore, so that it is impossible for high grade iron concentrate to adopt single wet low-intensity magnetic separation or high-intensity magnetic separation to concentrate iron mineral. Because of mixing the magnetite with hematite mineral in feed ore, recovery of iron of magnetite production system in the mineral processing plant is less than other mineral processing plants. Therefore, the research for increasing recovery of iron of the magnetite production system in the plant was undertaken. The paper presented the research for using dry magnetic separation to increase recovery of iron concentrate of the magnetite production system in the plant. It mainly includes dry magnetic separation test and wet magnetic separation and reverse flotation test. The test results indicated that dry magnetic separation is a important way to improve the feature of feed ore of the magnetite production system and to increase the recovery of iron. The recovery of iron may increase from about 70% to over 80%. The research also presented optimum operation parameters of the dry magnetic separator and the separation flowsheet. In conclusion, using dry magnetic separation to treat with feed ore of the magnetite production system in the plant to increase the recovery of iron is a feasible technique. The research present a new way for the mineral processing plant to made technology innovate to increase the recovery of iron concentrate of the plant in future.

Jan 1, 2014

By Lj. D. Andric

By the micronization-milling of the material, the size and the structure of its particles are changed and it comes to the increasing of the potential energy of the system as well as to the chem-ical activity of the material what is the result of an increased free surface and of the concentration of the grate defects, that is of the internal energy of the system. All these changes that are reached, show that new characteristics of treated materials are got by micronization process. Controlling the process of the micronization and by purpose directing of the new characteristics of the activated materials, we can have the positive effects and use them in more technologies. Talc is important nonmetallic mineral raw material that is widely used as either the basic raw material, or as filler. This has stimulated its technological investigation, as well as the investigation of its physical-chemical characteristics. In this paper are shown experimentally reached results of the physical-chemical characteristics of the talc during the process of the micronization in high energetic mill. In this paper, the optimum conditions of miconization of talc in high-energy-speed rotary mill and its influence micronization on a degree of Fe2O3recovery by hydrometallurgical methodes, are presented. The X-ray analysis of the obtained products showed that high quality talc with low content of can be obtained by these physical-chemical processes In this paper, the principles and application or fine and ultra-fine grinding high-energy attriton mill with small balls, enabling fast, efficient grinding, low energy consumption, short grinding time and easy handling will be described.

Jan 1, 2014

By Neill Bartie, Jacques Eksteen, Sharif Jahanshahi, Shouyi Sun

The gradual increase in Cr2O3 levels of UG-2 ores has become a matter of concern for platinum producers in South Africa due to the formation of chromite spinels in melters. The effect of bulk FeOx/MgO ratio, Cr2O3, temperature and oxygen partial pressure on phase stability and composition in the system FeOx-MgOSiO2- Cr2O3-Al2O3-CaO has been studied between 1400°C and 1600°C using the drop-quench technique. An increase in temperature was found to result in a decrease in [Fe/Cr]spinel. An increase in bulk FeOx/MgO caused Mg, Al and Cr in spinel to decrease, forming more magnetite relative to other spinels. [Fe]spinel decreased and [Cr]glass increased with a decrease in oxygen partial pressure.

Jan 1, 2003

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 V. E. Dementyev

This paper presents a brief overview of some IRGIREDMET advances in gold hydrometallurgy. Original impulse-percolation technology and equipment for intensive cyanidation of gravity concentrates have been developed and introduced into industrial practice by IRGIREDMET since 1980s (RF Patents N1593250). The process is based on leaching using special hydrodynamic and reagent conditions providing high dissolution rate for coarse gold particles. Gold and silver are precipitated from pregnant solution by cementation or electrowinning. There was also proposed an im-proved cementation method using zinc in a contact with electrically conductive material. The units including closed water recirculation, tails detoxification and semi-dry tails IRGIREDMET is well experienced in gold adsorption technology using ion exchange resins and activated carbons. The comparison of CIL and RIL processes were done for a number of gold mines, for example for Sukhoi Log gold deposit. The properties of prospective foreign and domestic ad-sorbents including strong-base, bi-functional and weak-base resins as well as activated carbons were studied. The Institute has developed some adsorption/elution technologies and equipment, such as a two stage RIP adsorption technology for gold/silver ores, an improved technology for gold elution from loaded resin and carbon, electrowinning cells for gold recovery from RIP and CIP eluates etc. Large scale ?Resin In Pulp? tests using weak-base resin were finalized and process design criteria were developed. Gold plant design is on progress at the moment. Improved technology for carbonaceous (preg-robbing) gold ores was developed. It was tested for some gold deposits including Sukhoi Log. It allows to overcome preg-robbing activities of ores treated and to improve dramatically performance of cyanidation and adsorption circuits. The studies on refractory gold ore treatment including bio-oxidation, pressure oxidation, roasting and ultra-fine grinding were conducted. Heap leach technology was tested and introduced by Irgiredmet for a number of Russian mines. Zinc cementation, activated carbon and ion-exchange resin adsorption were used for gold recovery from pregnant heap leach solutions. The options including combined technology ?Heap leach/ RIL or CIP? for clay ores were also developed and tested. The plant using developed technology is at construction stage now. The study on In-Situ gold leaching was conducted. The comparison of different gold lixiviants for this purpose was carried out. Gold recovery from pregnant leach solution by activated carbon and anionite including gold elution from loaded adsorbents etc. was also studied. In 2000 the In-Situ leaching technology was commissioned at Maminskoye gold deposit (Ural). The technologies for treatment of complex ores and by-products were proposed. For example, the technology of gold, silver, copper and zinc recovery from calcines after sulphuric acid production was developed.

Jan 1, 2014

By Tamal K. Ghosh

In this study, the QEMSCAN technology is used to acquire quantitative modal, textural, mineral association and liberation data on different products generated from with or without washing, fractionation by size and density using screens and heavy liquids/panning, which has provided significant information on the quality and beneficiability of four categories of low Grade iron ores from Jharkhand-Orissa region. The deposit of low Grade iron ore has been categorized into four categories viz. Grade-I with <45% Fe(t) a) containing shale rich type and b) BHJ rich type; Grade-II with 45-55% Fe(t) and Grade-III with >55% Fe(t) containing conventional flaky, hard, kanga, lateritic, shale and BHJ litho/ore types in varied proportions. Mineralogy is similar across all samples being hematite, martite, goethite, kaolinite and gibbsite. Banded Hematite Jasper has difficult liberation characteristics due to highly compact banded mode of silica mineral occurrence with hematite. In all categories, the grade dilution is by the presence of 1) ?Discrete gangue rich litho types? at lump size and 2) ?Within ore types?. The second type of grade dilution contains coating of gangue phases around the iron ore minerals and different degree of locking of gangue phases within iron ore minerals. Further characterization and beneficiation assessment details are discussed in this paper.

Sep 1, 2012

By Marko Hilden

"A stochastic model of mineral texture is discussed and used to demonstrate that grain association within the intact texture has a significant effect on the liberation characteristics of breakage products. The majority of previous models have simulated texture and liberation of binary systems. This new model is able to simulate complex multi-component (multi-mineral) aggregate textures and their breakage products. Grain size distributions can be defined for each of several minerals. Mineral-mineral associations can be controlled by inserting mineral grains within grains of another mineral. Repeated Monte Carlo sampling of the aggregate is used and the liberation properties of the fragments are calculated. These are analysed to generate data in a similar form as reported by mineral liberation analysis systems, including density distributions, liberation distributions, and particle class distributions. Simulations results are presented where the model has been fitted to complex sulphide ores with four minerals. Comparison of the simulated particles and experimental data show that the model is able to reproduce similar particle class distributions as measured by QEMSCAN. The texture of real complex ores can be simulated and fitted to conventional mineral liberation analysis data. The model should provide a useful and practical means of modelling the effects of mineral texture on separation processes and in geometallurgical models."

Jan 1, 2014

By A. Sand

Within stamp-charged coke making a large volume of coal is compacted to one single coal cake before entering the coke oven chamber. This is done by means of several falling stampers in a stamping machine having a mold nearly of the oven?s dimensions. Producing a high quality coke also from inferior coals requires a cake density of approximately 80% of the coal density. Besides that the industrial stamp-charging process demands a minimum mechanical strength of the coal cake to move it from the stamping mold into the oven chamber without failure. Densification and the build-up of cake strength were investigated earlier in stamping tests using a micro-stamping device. The quantities derived from these tests (as e.g. cake density or porosity) represent average values for the entire cake. Statements describing the local compaction state at different heights are difficult to achieve without destructing the cake. In order to gain better insight into the densification process and the inner structure of the coal cake a computational model based on the discrete element method (DEM) has been set up using 2 and also 3-dimensional simulation software. The stamper?s position and velocity as well as the force acting on the stamper were monitored and the model?s response was compared against measurement data from laboratory stamping tests. It was possible to reproduce the force and displacement pattern of the stamper in response to the viscoelastic properties of the cake using standard DEM bonding and contact models. Furthermore, the rearrangement of particles in response to the compaction by the stamper was tracked by calculating their displacement at the point the stamper hit the coal surface. The latter can also be used as indicators of particle deformation or breakage. By defining control points at different heights the particle displacement, stress and strain rates, porosity could be studied at different heights. Keywords: coke making, coal stamping, compaction, agglomeration, DEM, simulation

Sep 1, 2012

By L. S. Zhou

Germany-made AFX-100 multi-grade fluidized classifier, with exquisite built-in structure and unique novel design, materializes not only advanced and efficient classification, but also precise particle distribution and safe operation, in addition to lower energy consumption and operational cost. It, simultaneously in place of screw grader, water cyclone, and fine mesh sieve, is equipped with multi-function, and indicates superior advantage in comparison with other else grading facilities. As the third-generation equipment, which is efficient and modern, it, in China and therefore all over the world, will find wide application in processing both fine and ultra-fine iron ore resources. Industrial test, carried out in Benxi Steel?s Waitoushan Iron Mine, shows efficient classification, i.e., ?74µm particle contents in coarse, medium and fine products come to 6.09%,11.82% and 82.73%, respectively, while qualitative and quantitative efficiencies end up by 74.38% and 87.66%, respectively. Its separation efficiencies amount to 2.2 times as many as spiral classifiers, 1.8 times as hydrocyclones, and 1.3 times as vibration high-frequency fine screens. Another industrial test, which was practiced in Anshan Steel?s Donganshan Sinter Plant, indicates that classification qualitative efficiency comes to 65.06%, equal to 1.51 times as many as hydrocyclones; yield, 55.79%; -71µm particle contents in medium and coarse products, 42.02%; -71µm content in fine product, 95.42%; and concentration, 12.33%. Estimated separation indexes are as follows: Yield for concentrate at 31.22%, up 0.22% than that from general processing line; concentrate grade at 66.42%, up 1.13%; recovery ratio comes to 65.84%, up 1.28%, which, based on pilot study, results in 20 million yuan of economic return for Donganshan Floatation Plant.

Jan 1, 2014

Deposit of Jinbaoshan platinum group metals (PGMs) ore ranks the second in Yunnan province, China. Study on process mineralogy shows that the grade of copper and nickel in the ore is just 0.16% and 0.20% respectively. Moreover, the impurities magnesium and iron and silicon are rich in the ore. The copper and nickel sulfides in the ore, especially the minerals of PGMs, are finely disseminated with the gangues like serpentine. Fine grinding is necessary, and high content of MgO in the concentrate is inevitable through traditional flotation technology on the basis of process mineralogy studies. Achievements on process mineralogy studies are applied to guide the flotation tests successfully. Progress on flotation has been made through comprehensive studies. Suitable grinding by two stages is required for the finely disseminated PGM sulphide ore to achieve the liberation of valuable minerals. Stage grinding and stage separation shall be conducted for a better recovery of valuable minerals. The oxidation state of mineral surface of sulphides has a profound effect on flotation of the ultra-fine sulphides, especially the pentlandite. The combined use of collectors enhances the selective collecting on the ultra-fine and low-grade valuable minerals, is of critical importance.

Jan 1, 2014

By Y. Y. Zhou

This paper introduces the application of CRIMM high-gradient magnetic separator in refinement of feldspar powders as well as the supporting technical outfits needed by the refining process with the high-gradient magnetic separator as main equipment. It could reduce the content of Fe2O3 to 0.03% with a deferrization rate of 85.88% from the feldspar raw ore containing 0.17% Fe2O3by using the above refining technology, producing an ultrapure feldspar product.

Jan 1, 2014

By A. A. Sirkeci

In the scope of this investigation comparison between impact breakage and compression breakage were carried out for the separation efficiency of minerals using a chromite ore sample. The ore sample was broken below 1 mm employing a laboratory type roll crusher and an impact crusher. Concentration tests were conducted on -1+0.5 mm, -0.5+0.2 mm and -0.2 mm size fractions using a Wilfley type shaking table. Test results showed a remarkable difference between two types of breakage. Both concentrate grade and recovery was in the favour of impact crushing. Furthermore, the shape of the broken particles also showed differences such that in the case of impact breakage they were more spherical compared to compressive crushing. The results of the shaking table con-centration tests showed that a concentrate assaying 48.4% Cr2O3 were obtained with 78.5% recovery in the case of impact breakage. On the other hand the concentrate grade and recovery values were 48.8% Cr2O3and 52.4% respectively in the case of compression crushing. The losses in the tailings were also in favour of impact breakage proving that differential breakage occurred between chromite and gangue minerals.

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 A. Ceylan

Pyrite is present as a gangue mineral in most of complex sulphide ores and most of time it is removed as a tailing. However, beneficiation of pyrite from tailings could be important because of its economical value and for the environmental concern. This paper presents a research for the enrichment of pyrite from copper plant tailings, Siirt-Madenköy/Turkey, by flotation. Siirt-Madenköy copper mine is operated by Park Electric Production Mining and Industry since 2005. In order to obtain the pyrite from Siirt-Madenköy copper plant tailings, laboratory test work has to be done to determine the type of reagents, the flowsheet, and the size of plant. The objective of the company is to develop a pyrite flotation circuit for concentration of pyrite from tailing dam to obtain 500.000 tons/year pyrite concentrate. There are about 3 million tons tailings that containing pyrite in the tailings dam. Experiments were carried out with three different types of tailings from the plant and the pyrite concentrate with 46% Fe and 90% recovery has been obtained. Therefore, this study shows that high grade pyrite with high recovery can be recovered from the tailings.

Sep 1, 2012

By J. Quinteros-Riquelme

Despite increasing demand, the supply of silver is limited by its inadequate recovery from ores. Due to its scarcity in nature, its high ore variability and complex mineralogy of current silver deposits, its recovery by mineral froth flotation presents a real challenge for process engineers. A silver ore often contains significant amounts of five to ten different silver minerals and knowledge of the mineralogy is a necessary precursor to flotation testing. In this work, a complex silver ore was treated by using batch laboratory flotation, in an effort to find the best experimental conditions to obtain the optimal silver recovery. Mineralogical characterization of feed samples was conducted using a combination of tools, namely the mineral liberation analyzer (MLA) and inductively-coupled plasma mass spectrometry (LA-ICP-MS), which indicated that most of the silver occurred as ?invisible? silver in pyrite. The pyrite assay of the ore was approximately 4%. The ore was processed in two flotation stages. The first stage, sulphide flotation, aimed to collect a sulphide mineral rich concentrate; then a non-sulphide flotation stage was performed by adding sodium sulphide and collectors to the remaining material in the cell, with the objective of obtaining a pyrite rich concentrate. To reach the target recovery of silver from this ore, various variables were altered. In the first stage: mixed collectors, activators, dispersants, and mainstream inert grinding were assessed. In the second stage, the conditions for sulphidization and subsequent flotation were both investigated. From the grade recovery curves for silver and sulphur it was possible to observe a similar metallurgical behavior for both elements, supporting the results given by the mineralogical characterization. Keywords: silver oxide, froth flotation, sulphidization, mig

Sep 1, 2012