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By S. K. Pan, M. P. Srivastava, N. Prasad

"Dalli mines of Bhilai Steel Plant, India is fully mechanized iron ore mine having wet processing system. It has a capacity to treat 5 Mt of ROM. In processing circuit of Dalli mines, scrubbing, wet screening and classification operation is being carried out. Average slime generation for the last five years is about 14% of ROM. As the mining has reached to the lower benches, fines generation is more. As a result, very fine and heavy particles, which settle fast, are being discarded with the slime to tailing pond. These heavy and faster settling particles were causing jamming in the thickeners.Laboratory investigations were carried out at Research and Development Centre for Iron and Steel (RDCIS) to suggest a suitable scheme to recover high quality fines so that the availability of thickener can improve. The slime samples were first treated in a floatex density separator. The concentrate obtained from the floatex density separator was treated in hydrocyclone. Laboratory investigations indicated that the slime with 49% Fe, 12.7% silica and 10.7% alumina can be upgraded to 62.1% Fe, 3.3% silica and 2% alumina with 36% material recovery. Based on the laboratory studies ,a system was installed at Dalli minesThe general arrangement of the system is shown in Fig. below."

Jan 1, 2003

By Aubrey Mainza, Malcolm S. Powell

"A hydrocyclone with two vortex finders, named the three-product cyclone (3PC), has been successfully tested in the Platinum industry for dealing with the dense Chromite found in UG2 ores. This dense component preferentially reports to the cyclone underflow, resulting in an over-ground fine Chromite component in the final product. The dense media effect caused by a high concentration of this in the cyclone feed produces a coarsening of the cyclone overflow, which results in loss of recovery through over-size silica in the PGM carrying component material in the float feed. The fine barren particles of Chromite that report to the overflow are recovered through entrainment in the flotation process, resulting in detrimental contamination of the slag produced from the concentrate.Data from many industrial scale tests of the 3PC have shown that three distinct products are obtained when the inner vortex finder length (LIVF) is extended to the region either above (normal classification) or below (reverse classification) the transition zone (a region were the inner and outer overflow streams are identical). Due to wear problems arising from extending the IVF deep into the cone of the cyclone, it is advantageous to use the shorter IVF. Only the normal classification results are reported here, but similar outcomes (to opposite overflow streams) were obtained for the reverse classification. The results showed notable differences in the percentage split of the plus 100µm material in the product streams, confirming that three distinct products are discharged from the 3PC. About 12% of the plus 100µm material in the feed reports to the middlings stream, 1% reports to the final product, and the remainder to the cyclone underflow.Results of silica and chrome splits to the three distinct products namely, the inner overflow (INO), the outer overflow (OUO) and the underflow (U/F) are given in Table 1. These show that the 3PC can be used to recover coarse silica through screening the middlings product - which has a high silica content. When the vortex finder ratios (ratio’s of cross-sectional areas) are carefully selected, the split of plus 100µm silica to the middlings product ranged from 2.9 to 9.6%. Large amounts of oversize silica and chrome report to cyclone underflow, explaining their high percentages in the underflow stream."

Jan 1, 2003

By G. S. Hansford, G. E. Searby

The rate of bioleaching of pyrite at 70ºC by a thermophilic archaeal culture was measured as a function of the solution redox potential by the staged addition of pyrite to a batch system. The results were compared to the rate of ferrous iron oxidation over the same potential range to determine the applicability of the multi-sub-process leaching mechanism developed for mesophilic bioleach systems.

Jan 1, 2003

By Francisco Vicuña, Miguel Becerra, Nelson Iglesias

"The following article presents the development of a dynamic tool for the estimation of Jb/Jc rate (ball filling level / total load filling level) of a SAG mil operating in a single stage mode. Using the methodology detailed in this article, it is now possible to have a dynamic estimation tool in the operation, which enables strategic decision making and achieving a continuous development in process optimization. The estimating of the load filling level (Jc) was conducted using a power model, which in this case corresponds to the C-Model developed by (Morrell, 1993) that was calibrated by measuring the load filling levels (Jc) and balls (Jb) using the FARO laser scanning technology by means of Grind-Out and Crash-Stop procedures during the year 2013 and 2014. Finally, to estimate the dynamic filling level of full charge, Jc, three independent models were developed that allowed to feed the adjusted power model: •,SAG mill discharge grate slot wear model •,SAG mill internal volume wear model •,Ball filling level estimation model."

Jan 1, 2014

By Heribert F. Broicher, Arne Volland

"The analysis of laser-induced fluorescence (LIF) combines remote sensing techniques with laser spectroscopy. Over variable distances different rock types are identified or changes in the quality of one rock type are recognised. LIF Analysers operate non-destructive, non-contact, on-line and in real-time. Installed over conveyors or over driveways the analysers ""look"" at the moving bulk solids 20 times per second and provide in real-time information for downstream sorting, blending or optimisation of processing. LIF Analysers recognise rock types (hardness information or dilution control), degrees of alteration, degrees of oxidation and –semi-quantitative- content of certain minerals in an ore. Only under favourable conditions quantitative assay information can be obtained, as e.g. the phosphorus content of Kiruna type iron ore.The main application of LIF Analysers is seen in big open pit operations, where the muck is trucked to an in-pit crusher and the crushed rock conveyed out of the pit to its respective destination: e.g. the primary high grade ore to the mill, the low grade or oxidised ore to the leach pads and the internal waste to the dumps.In underground mining and especially in block caving operations dilution control is of utmost importance. Here a LIF Analyser mounted on the back of a pick-up truck can be moved from drawpoint to drawpoint and quickly assess the degree of dilution.Closer to the mill the stockpile management based on LIF analysis will lead to stockpiles sorted according to rock type (hardness), degrees of alteration and oxidation. In case of direct feeding rom ore to the mill the knowledge of the type and quality of all the material between the in-pit crusher and the mill facilitates optimisation of e.g. reagent dosage."

Jan 1, 2003

By Cheng Gan, Gui Xiahui, Li Shulei, Cao Yijun, Liu Jiongtian, Wu Lun

Flotation rate constant is an essential parameter in the flotation process. The fine coal sample utilized in this investigation is anthracite from the Shenhuo mine in eastern China. Fine coal flotation rate tests were conducted to compare the flotation rate constant at constant power input with that at gradually increasing power input. Results indicate that the flotation rate constant decreases with the flotation process and increases as the flotation energy is increased. In addition, the flotation rate constant is close to the maximum value. The increasing trend of the flotation rate constant gradually slows down as the flotation energy input increases.

Jan 1, 2014

By Peter Ay, Elena Geldt, Satyanarayana Narra, Claudia Glaser

"As part of an extensive research and development project, the technical and technological implementation of the patents DE 10 358 245 B4 and WO/2006/056172 was developed with the goal to present a system for the innovative roll- agglomeration method exhibiting a) a modular setup, b) high productivity and c) suitability for the use of fibres of different applications and product qualities (high technical availability). The processability of the rarely adapted raw fibre materials into high-value intermediates brings forward their application in various processing industries dealing with the production of fibre reinforced plastic composites, heat and sound insulation materials as well as with the gas and liquid cleaning systems. The innovative fibre agglomeration presented in this work is performed by a combination of rolling and pressing the fibres inside a geometrically pre-defined roller table, in which the fibres are forced to bound through entanglement / interlocking and develop into agglomerate. The agglomeration process is carried out in a circular roller path with a rectangular cross-section. For improving the adhesive properties, and thus the quality of the agglomerates, the boundary surfaces can be covered / patterned / lined / coated with various materials. The resulting roll-agglomerates are characterized by different quality parameters such as mass, shape, porosity and stability. The properties of the agglomerates can be modified based on the end-product requirements by slightly modifying the process parameters such as filling ratio, residence time, roll-geometry, procurement of the boundary surfaces, etc. as well as the input material properties such as fibre type, fibre fineness, fibre length, etc. This work carries extensive work on the roll-agglomeration system to assess the effectiveness and the variability based on the product specifications. Agglomerates were produced with wide variations of system parameters with varying roller table liners and based on evaluation of the produced agglomerates with respect to their mass, the geometrical dimensions, their porosity and stability."

Jan 1, 2014

By M. Ito

Cobalt-rich ferromanganese crust and nodule ores from seamount areas contain volcanic and sedimentary rocks as substrate or nuclei. These ores require mineral processing to remove the sub-strate/nuclei rock before smelting. This paper reviews experimental results of previous investigations. Observations and analysis of 10 samples from different localities were carried out and it was found that the liberation ratio of crushed product was high even at coarse size fraction, 0.5mm to 4mm. Experimental and calculated results in the smelting stage confirmed that the separation product satisfies the standards of the subsequent smelting process if the substrate/nuclei rock is removed from the 0.5mm to 4mm fraction with high separation efficiency. There was a density difference between the substrate/nuclei rock and the ferromanganese component. Thus the coarse sized sample was treated with gravity separation; air table separation was used as a dry method and jig separation as a wet method and high grade values with high recoveries were obtained by both kinds of gravity separation.

Jan 1, 2014

By Marina Nicolova, Irena Spasova, Plamen Georgiev, Stoyan Groudev

Different strains of "silicate" bacteria were used to improve the quality of kaolin by different ways of treatment. All strains formed large slimy capsules consisting of exopolysaccharides and were related to different species of the genus Bacillus, mainly to B. circulans and B. mucilaginosus. It was found that even a short contact of some hours of well developed cultures of these bacteria resulted in improvement of the bending strength and the other ceramic properties of the kaolin. The improvement was connected with the action of some secreted microbial metabolites such as soluble heteropolysccharides, monosugars and organic acids. The best results were achieved by continuous cultivation of bacteria in the presence of kaolin with a high relative humidity and subjected to periodic stirring.

Jan 1, 2014

By P. Chris Pistorius, Johannes Sono, Rossouw Sono, J. J. Kobus

Different coal properties are important in SL/RN (coal-based rotary kiln) direct reduction of iron ore, and in electrical smelting of prereduced iron ore. These differences were highlighted when a plant which processes titaniferous magnetite had to change to different coal types after decades of operation. Laboratory simulation was used to evaluate two candidate coals, which were similar in volatile content and rank, but differed in reactive maceral content. Direct reduction was evaluated by isothermal experiments using a packed bed of ore and coal, measuring the off-gas composition to determine reaction rates and departure from equilibrium. These indicated reduction to be under mixed control, and quite sensitive to temperature (confirming that the coal reactivity is of importance). An aspect of electrical smelting was assessed by determining dissolution rates of the coal in molten iron at 1550°C. Dissolution rates did correlate with differences in coal structure, as determined by X-ray diffraction, with the more ordered ("more crystalline") coal dissolving faster. The conclusion is that the coal which is more reactive during direct reduction is less reactive during dissolution. However, it is concluded that controlling the temperature during direct reduction offers a feasible method to reconcile the two process steps.

Jan 1, 2003

By Isaak I. Maksimov, Tatyana E. Koltunova, Mikhail F. Yemelyanov, Liudmila A. Otrozhdyonnova

"INTRODUCTIONMetals losses amount up to 50% in coarse fractions in (>100 µm) and composite particles, and to 20- 25% in fine fractions (<10 µm) at non-ferrous floatation concentrating plants of the CIS. Therefore, reduction of metals losses in difficult fractions is of high significance.IMPROVEMENT OF FLOATABILITY OF COARSE AND COMPOSITE PARTICLESReagent regimes with application of strong collectors – xanthates ?5-?8, combination of butyl xanthates and aerofloats ?10-?12, butyl xanthates with hydrocarbons are proposed for this purpose. Application of such reagent regimes for copper and copper-molybdenum ores permitted to increase copper and molybdenum recovery by 0.5-3.9%.Studies, performed by means of specially designed non-frothing flotation machine with independently controlled agitation intensity and narrow size-ranges of air bubbles, established that the best results are achieved with employment of bubbles of 0.5-0.8 mm size regarding particles of any size, with small amounts of up to 2 mm size “transport” bubbles to be expediently used for floatation of coarse particles.Energy dissipation in the main volume of floatation cells must be lower than 0.2-0.25 m2/s3.Performed experiments permitted to formulate requirements to development of machine for floatation of coarse and composite particles. Such floatation machine with volume of 8.5 m3 provided for weak agitation in the main volume of floatation cell and uniform distribution of coarse particles throughout the depth owing to establishing of pulp circulation with upward flows. In addition, in the upper part of floatation cell where agitation is considerably weaker, favorable conditions are created for attachment of particles to bubbles. Testing of this floatation machine demonstrated a 7.5% increase in recovery of +0.2 mm particles in pyrite floatation and a 12-14% increase in recovery of +0.2 mm particles in apatite floatation as compared with a reference floatation machine."

Jan 1, 2003

By Li Maolin, Cui Rui, Wang Guanghui

"As the stirrer speed directly affects the motion of grinding media, and hence the interactions with material particles to be ground, the rotation speed of a stirred mill is well recognized as one of the most important factors affecting the grinding performance. In this work, the effect of stirrer speed on grinding performance in terms of grinding rate and grinding energy efficiency was quantitatively investigated. Batch wet grinding tests of quartz powder at different stirrer speeds were performed, using a self-made horizontal stirred mill with alumina balls as grinding media. Grinding time, operating power and the sizes of ground product were recorded to analyse the grinding performance. The test results showed that grinding processes followed the first order grinding kinetics. The grinding rate constant increased with the increasing stirrer speed. Based on the grinding kinetics, the grinding energy equation was established. The energy utilization coefficient in the energy equation can be used as an indicator of energy efficiency. The energy efficiency decreased with the increasing stirrer speed. Quantitatively, with the stirrer tip speed increasing from 4.25m/s to 9.35m/s, the grinding rate constant was improved by 441.47%, whereas the energy utilization coefficient was decreased by 39.35%. The grinding rate constant and energy utilization coefficient can be used to evaluate the grinding performance when the grinding conditions need to be adjusted. The adjustment of grinding conditons would be optimal when grinding rate get significant improved with little decrease of energy efficiency."

Jan 1, 2014

By D. Szyszka

During passing gas bubbles through mineral suspensions, some mechanical carryover of fine particles to the froth layer always takes place. The entrainment of mineral particles is influenced by many parameters, mostly by the particle size and the concentration of the frother. The paper deals with influence of selected frothers (methylisobutylcarbinol (MIBC), a-terpineol, and hexadecane tricosaethyleneglycol ether (C16E23)), common laboratory flotation frothers, on the mechanical car-ryover of quartz, a typical gangue mineral component of ores. Entrainment tests were carried out in a laboratory Mechanobr flotation machine with quartz particles suspended in aqueous frother solu-tions. The mechanical recovery of quartz in the presence frother was increasing with time and reached plateau after about 20 minutes of flotation. The plateau level of quartz recovery depended on the frother concentration. Initially an increase of the plateau with frother concentration was observed until the plateau reached the highest level called the maximum recovery emax. The emax can be used as a parameter to characterize the ability of frothers to entrainment. In the studied quartz-frother flotation system the maximum entrainment was 32%, 50% and 80% for methylisobu-tylcarbinol (MIBC), a-terpineol, and monohexadecane tricosaethylene glycol ether (C16E23), re-spectively. A comparison of the maximum entrainment factor emax with other, known from literature, indices such as bubble critical coalescence concentration (CCC), dynamic foamability index (DFI), Jw, e =25%revealed, except DFI, their similarity.

Jan 1, 2014

By Sung. Hyejin, Kyoungkeun Yoo, Oh-hyeok Kown

The sediments near coasts and ports in Korea have been found to be contaminated with heavy metals and organic matters. So far the sediments have been dumped to landfill sites or ocean. However, the number of available landfill sites is decreasing and ocean disposal of wastes was strictly prohibited. Although physical separation processes have been found to be useful for the remediation of contaminated soil with heavy metals, because the sediments consist of fine particles, it is difficult to remove heavy metal component by physical separation processes. Furthermore, the sediments contain organic matter, so there is a concern about strong stink during the sediment treatment. The present study is aimed to develop the treatment process for removing heavy metals and organic matter from the contaminated sediments. The heavy metals and organic matter were oxidized and dissolved by electro-generated chlorine, and the chlorine used is regenerated and circulated in the leaching process. This system has economic and environmental advantages to reduce the wastewater and the oxidant consumption. The leaching results show that the metal removal efficiency increased to more than 99%, and more than 50% of organic matter was decomposed.

Jan 1, 2014

By P. M. Solozhenkin, V. P. Nebera, V. D. Skorohodov

"Aqueous dispersions of air specifically prepared on the basis of flotation reagent solution acquire active properties in relation to the solid surface and may be imply as a medium for flotation ores. Such aerated solutions were defined as Activated Aqueous Dispersions of Air (AADA) with 5-6:1 ratio and the procedure of mineral separation was defined as a flotation process under non-equilibrium conditions. These procedures differ from conventional flotation mainly in reagent interaction with minerals through their adsorption films on gas bubbles simultaneously forming flotation complexes. Gas-liquid mixture is kept till an adsorption layer of reagents close to the limit value is formed on the surface of bubbles. The theoretical basis of AADA is considered.The results of two-phase gas- liquid mixture (AADA) were studied. Two versions of AADA were considered. Electrical surface potential of the air bubbles with the surfactant film, untreated minerals particles in Coulomb attraction and flotation complex formation were analyzed. Special flotation machines were constructed for separation of mineral suspension in air dispersion, whose effectiveness was confirmed in flotation of apatite waste of Kovdor ore. FK-9 machine introduced on Kovdor iron ore combine for the recovery of apatite from current departures of factory. The froth product contained 7.2 % P2O5, with recovery of 44 % apatite, which was processed for getting melted phosphoric-magnesium fertilizers."

Jan 1, 2003

By P. M. Solozhenkin

"Galvanochemical process (GChP)) cleaning of sewages is realized in the field of shortcirquited galvanic elements from the mixture current the materials place in purification’s solution and form multitude galvanopairs without external electric field in presence oxygen of the air. The galvanochemical process is electrochemical process utilizing galvanic pairs: coke - iron, iron - copper and others and process does not require chemical reagents.The effect of basic parameters of the cleaning effectiveness have been studied depending on oxidizing of galvanopairs. Adjusting nature, type of galvanic pairs and forming three component system possible to enlarge emf circuits to 2.378 V.The role of ?2, as basic agent, for generation of hydrogen peroxide and hydroxyl ions.It was stated, that removing of metal ions from solutions occur mainly on account of sorption and hydrolytic sedimentation of iron oxihydrates.Determined separate stages of the process: coagulation, sorptions of admixtures on freshly formed ferric oxides and oxidizing destruction of organic components of effluents in presence of ?2 ? ?2?2. Shown efficiency of the method for removing of Cu, Cr, Ni, Zn, As ions, as well as fluoride, phosphate and cyanide anions and oil products, surface-active and flotation reagents. Cleaned water can be recycled for some processes non-critical toward residual concentration of admixtures, as total salt contents is lowered on 60-75 % and reaching limits of concentration for toxic components.The concept of high power unit creation was developed, and galvanochemical pulsator is presented. The pulsator is not expensive, and exploitation expences are low, as well as servise is simple with high effectiveness, and capacity. The galvanoflotation process is developing, combining galvanochemistry and flotation of hydrofobic admixtures (oil, surface-active agents).The galvanochemical flotators are presented."

Jan 1, 2003

By Nóra Schreithofer, Zoltán Jávor, Kari Heiskanen

"One of the challenges the mineral processing industry is facing is caused by the fact that water resources in mining areas are becoming very limited and the cost of water is increasing. The water sources in arid regions often have high salt content. Environmental regulations are forcing plant operations towards completely closing the water cycles within plants. This means that impurities (salts, reagents, ions dissolved from minerals, etc.) accumulate within the circuit that will affect the flotation performance. Water purification can significantly increase the operating costs therefore it should be carefully considered weather the impurities need to be completely removed or is there a tolerable level of impurities that can still be left in the process water without significant deterioration of the flotation performance? Several additional questions arise: what are the tools that help identify what is a tolerable level of impurities? How do the different impurities interact and what is their effect on the process? The effect of frothers on the dynamic properties of air/liquid interface in different size-scales has been extensively studied by the authors in the past. Based on these studies a frother characterization framework was developed that systematically examines the dynamic surface properties of the air/liquid interface in relation to the bubble size. This work can be considered as tool that could be used for the above mentioned purpose. The present study investigates weather the same frother characterization framework can be applied for systems where both frother and different types of salts are present. Nasfroth 240 was used as a frother, in combination with structure-breaker KCl or structure-maker NaCl and CaCl2. Bubble size measurements in laboratory scale mechanical flotation cell and laboratory flotation column and dynamic surface property measurements (dynamic surface tension and dilatational elasticity) were performed. The results highlighted the addition of salt to the frother solutions significantly decrease the bubble size and increase the froth high. The coalescence behavior of bubbles showed correlation between the D32 and ionic strength of salts. The results highlighted that the studied structure maker and structure breaker salts effect the dynamic surface properties in different way."

Jan 1, 2014

By Wu Tao, Lu Shijie, Xia Xiaoou, Zhang Ming

The impeller and stator are the most important components that can significantly influence the performance of flotation cells directly. The performance of the impeller and stator of KYF flotation cell is revealed by CFD (Computational Fluid Dynamic) simulation in this paper. A method of obtaining the circulation volume is proposed. The circulation volume is proportional to third power of impeller diameter. And the circulation volume increases linearly with the increasing of the speed. CFD simulation can draw the conclusions that there is a proportional relationship between power consumption, third power of speed and fifth power of impeller diameter. CFD prediction results agree with the theoretical formula. The difference between the forward and backward impeller is analysed in the paper. The circulation volume of the backward impeller is obviously larger than that of the forward impeller under the same condition, but power consumption of the backward impeller is lower. It is demonstrated that the impeller and stator system of KYF flotation cell is an efficient and reasonable stirring mechanism. CFD simulation could be reliably used in flotation cell design and optimization.

Jan 1, 2014

"The thiosulfate leaching process developed by Barrick to treat sulfidic high preg-robbing gold ores uses calcium thiosulfate as the leaching reagent for ores pre-treated by pressure oxidation, resin for gold recovery with sulfite/trithionate elution and reverse osmosis as a means of reagent recovery. A large portion of the research that led to the development of the technology was based on previous studies completed by different groups over the years, mainly focused on the ammonium thiosulfate system. Operational limitations in the use of the ammonia-containing recycled water in the pressure oxidation circuit were some of the main drivers for the change from ammonium to calcium thiosulfate for the development of the industrial scale process. One of the main aspects for successful gold extraction and recovery in the thiosulfate system is the pseudo-equilibrium reactions that drive distribution of the different gold species (in solids, solution and on resin) in the system. Previous studies have been focused on the thiosulfate reactions and equilibrium constants for the oxysulfur ions (thiosulfate, trithionate, tetrathionate). However, the literature around the effects of the different metal-oxysulfur complexes (Cu and Hg complexes) that form when the ore is in contact with the leaching reagents, and the related effects on stability of the gold complex is limited. The main changes in the gold complex chemistry and stability in the calcium thiosulfate system as compared to the ammonium and sodium equivalents, as well as related effects on gold recoveries, were investigated in the presence of different types of double refractory ores. INTRODUCTION Barrick has developed a thiosulfate leaching process to treat double refractory gold ores, by combining the use of acidic and alkaline autoclave pre-treatment with thiosulfate resin-in-leach (RIL). The process currently in operation at the Goldstrike mine (the TCM process), uses calcium thiosulfate as the leaching reagent, resin for gold recovery with sulfite/trithionate elution and reverse osmosis as a mean of reagent recycle. The main feed to the process plant is highly preg-robbing sulfidic ore from Goldstrike’s open pit. Prior to feeding the pressure oxidation circuit, the ore is processed through the crushing and grinding circuits and treated in preparation for acid or alkaline autoclave processing (POX)."

Jan 1, 2018

By K. Saberyan

Zirconium and hafnium are two important elements in nuclear industries. Zirconium is used in fuel rod for its low neutron absorption. Hafnium should be separated from zirconium, because it has higher neutron absorption cross section. In this research, separation process of the mentioned elements from (Zr+Hf)Cl4 mixture produced in the Zirconium production plant (ZPP) of Iran (Esfahan) was studied employing solvent extraction method in the nitric acid medium by using tributylphosphate (TBP) as solvent, and kerosene as diluent. The effects of nitric acid, sodium nitrate and amount of extractant, zirconium concentration in aqueous phase, phase ratio, agitation time, and mixer agitation rate were investigated on the separation process. The process was optimized at 5 M nitric acid, 1 M sodium nitrate, 60% (v/v) TBP. The optimum values for phase ratio, agitation time and agitation rate were 1.5 min and 500 rpm respectively. In this condition, the zirconium extraction efficiency, and separation factor were 65.1% and 205.59, respectively. Finally, we accessed to nuclear grade in this research.

Jan 1, 2014