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By G. P. Wong

"In the Inco matte separation process, a slow-cooled converter matte is separated into three main discrete mineral phases: chalcocite (Cc), heazlewoodite (Hz) and a Cu-Ni-Fe alloy. After magnetic removal of the alloy, Cc and Hz are separated by flotation at pH>12 with diphenyl guanidine (DPG) as both collector and frother. High selectivity is achieved in rougher flotation. However, in later flotation stages such as in the middlings circuit, as oxidation takes place, Hz becomes highly floatable, resulting in a very poor separation between Cc and Hz.Starch and dextrin as Hz depressants were evaluated on the middlings circuit feed and showed no positive impact on Cc/Hz separation selectivity. Ethylene diamine tetra-acetic acid (EDTA) extraction showed the existence of abundant surface Cu and Ni ions. The use of triethylene triamine (TETA) or EDTA in flotation did not improve Cc/Hz separation selectivity. Microflotation tests were carried out on pure synthetic Cc and Hz minerals. It was found that Hz did not float in the presence of DPG. However, Hz conditioned with either copper sulfate solution or in contact with Cc floated readily in the presence of DPG. It is concluded that the major reason for Hz flotation in the middlings circuit is due to Cc oxidation releasing Cu ions that adsorb on the Hz surface making it reactive with DPG thus rendering the Hz floatable."

Jan 1, 2003

By M. Guo

Coal-based Direct Reduction in Interior-combustion Shaft Kiln (CDR/ISK) is a brand-new technique. Compared with the traditional Coal-based Direct Reduction (CDR) technique, its main character is to use Interior-combustion Shaft Kiln (ISK) as the reactor of direct reduction. After being crushed and grinded, iron ore is made into green pellet, which will be surface-coated by coal fines. Then, the surface-coated green pellet can be directly reduced in ISK. The pellet should not be too dry and should be charged from the top of ISK. Oxygen-contained air should be blasted into ISK to keep the temperature in it higher than 1000 degrees centigrade, at which iron oxide will start direct reduction. The reduced pellet will be discharged from the bottom of ISK and after de-surface-coated, spherical Direct Reduced Iron (DRI) can be gained. The volume of carbon monoxide in the off-gas discharged from ISK is less than one per cent. By using this technique to get one tonne DRI, the consumption of coal is about 300kg of fixed carbon, which is much lower than the energy consumption by using other CDR techniques. There is a lot of complex refractory iron ore in China, which remains unexploited. The iron-bearing minerals in this kind of the iron ore can not be beneficiated economically by present technique of gravity, magnetic, flotation or magnetic roasting because the iron minerals are too very finely disseminated to be liberated, or, the iron minerals are too similar to gangue to be separated each other. By using CDR/ISK, complex refractory iron ore can be directly reduced in lower temperature and all kinds of iron mineral can be turned into iron metal. As the grains of iron metal growing larger during direct reduction, magnetic separation can be used to separate iron metal from gangue mineral, thus high-grade iron metal fines can be gained. According to the experiments, the grade of iron metal fines is above 90 percent and the recovery of iron is higher than 90 percent. The consumption of coal to process one tonne of complex refractory iron ore is only about 90kg of fixed carbon.

Jan 1, 2014

By D. Chakraborty, Neeraj Kumar

"The study provides the comparative analysis of the performance of water only cyclones and hydrocyclone for iron ore fines processing at Joda Iron ore processing plant, Tata Steel. Joda iron ore deposits have higher proportion of kaolinite in the finer fractions and are meant to be separated with cyclones. The iron processing flowsheet of Joda comprises of water only cyclone for beneficiation of iron ore fines. Water only cyclones are used for the beneficiation of fines in the iron ore processing industry and have a larger cone angle compared to that of conventional hydrocyclones to enhance the density effect in the separation. They are aimed to achieve better product quality of underflow however; the desired result could not be achieved at the Joda processing plant. The water only cyclones were operating at the corrected cut-size of about 60 micron with an imperfection of 0.40 and water split to underflow was approximately 10%. The overall Fe recovery from the water only cyclones were 60%. Since the quality of fines produced from the water only cyclone couldn’t be improved, an attempt was made to process the fraction in the conventional hydrocyclone to achieve the desired product quality. The trial results indicated better product quality with the Fe recovery of 72% at corrected cut-size of 70 microns and imperfection of around 0.29. In view of above results it was recommended to replace the water only cyclones with hydrocyclones to achieve higher product quality of about 60% Fe content.INTRODUCTION Water only cyclones were installed at wet plant, Joda to process the classifier fines where the cyclone underflow is considered as concentrate and overflow is discarded as slime. Because of the lower capacity of the cyclones 30% of the classifier overflow was bypassed directly to thickener. Apart from this the quality of fines produced from the water only cyclone couldn’t be improved further hence an attempt was made to process the fraction in the conventional hydrocyclone to achieve the desired product quality and quantity. Hydrocyclone was installed at Joda after replacing stub-cyclone and came into operation on 23rd Aug’ 2017.The process variables of water only cyclones and hydrocyclones are tabulated below:"

Jan 1, 2018

By S. M. Saghaeian

The studies on the product finer than 12 mm due to crushing and sizing plant of Gol-e-Gohar Iron Ore mine showed which this material contains significant amount of valuable iron minerals. Based on the carried out experimental studies on representative samples of fine hematite iron ore, a processing flow sheet was designed to upgrade iron content. This plant is known as first hematite iron ore enrichment plant in Iran which the dry medium intensity magnetic separators (with magnetic field intensity 4500 gauss and high gradient) has been used. The main objective of the plant is production of high iron product with iron content more than 61% and weight recovery more than 55% from the feed with iron content of 54%. In this plant, at first material are screened by a single deck screen (6mm), then oversize particles is separated at one stage by magnetic separator, while undersize ones at two stages. Based on the results of experimental tests, a final high iron product with iron content of 62.4% and weight recovery 63.9% can be achieved. It should mention which the iron content can be enhanced through increasing the speed of magnetic separators especially at the part of separation of finer iron ore.

Jan 1, 2014

By S. N. Shahcheraghi

Grinding is one of the most important and expensive steps in mineral processing allocating about 70% of the total energy in the plants. Nowadays, for optimizing the energy consumption in these equipments, the rock behavior and its size distribution during the crushing have been normally predicted using selection and breakage functions to be able to optimally model and design grinding circuits. For this purpose, the case of Miduk copper mine in Kerman province, Iran was studied. The samples were taken from primary ball mills feed and were subject to screen analysis to achieve uniform sizes. Then, selection and breakage functions were determined at the different grinding times in laboratorial ball mill. Finally, ore size distribution in different grinding times was estimated using MATLAB software

Sep 1, 2012

In the present work, the flotation behaviours of zircon, rutile and ilmenite using sodium oleate as collector in absence and presence of depressants were thoroughly investigated. The maximum in the flotation recovery of any of the above minerals falls within similar pH ranges. A range of inorganic and polymer depressants were examined in order to improve the separation of zircon from rutile and ilmenite. Optimum values of conditioning pH and depressant concentration to achieve maximum recovery and best selective floatability of zircon were obtained. Selective flotation of zircon from Ti-bearing minerals was anticipated from single mineral experiments under different pH values, depressant and collector conditions.

Jan 1, 2014

By Xiaodong Jia, Williams. Richard A.

This paper describes the recent developments, arising from research at Leeds, in the computer modelling of packing of complex shaped particles and prediction of physical properties of the structures represented by the packing. The computer model DigiPac, is capable of packing particles of any shapes and sizes in a container of arbitrary geometry. The ability to predict packing structure of real particle shapes and to compute directly some structure-dependent physical properties (such as liquid permeability, mechanical strength/ stability, compaction and sintering, dissolution and leaching, etc.) is obviously highly desirable and has significant potential in industrial applications. Examples are presented relating to the packing of granular materials.

Jan 1, 2003

By Matti Kongas, Kari Saloheimo, Antti Remes

"The paper studies the control performance of the flotation process as a function of the measurement accuracy and sampling frequency of an on-stream XRF analyzer, using a simple dynamic model. An additional aim is to assess how the economical result of a mineral flotation process depends on the quality of process control based on the on-line elemental assays.An on-stream XRF analyzer measures the concentrations of slurry lines in a continuous cycle from several process points. The control performance depends on the analytical accuracy and sampling frequency of the concentration measurement. With a long cycle time, the state of the process changes before a new measurement becomes available. With short measurement times the statistical variance of the counted X-ray pulses increases, increasing the random error in the analysis. In addition, the measurement accuracy depends on the concentration of the component to be measured from the slurry.To quantify the effect of analysis error and frequency to process control, a simple dynamic process model is created in the Matlab environment. Data from a copper flotation circuit is used as a test case. The process model comprises a first order reaction equation and the grade-recovery -relationship estimated from process data. The control was modeled using the control strategies implemented into a rule based advanced control system.The economical performance of the control was studied by calculating the overall net smelter return at various analyzer parameter combinations. The economical performance of the process declines strongly when the sampling cycle is increased. In studied case the sample measurement time did not have a significant effect on the results. The economical performance of the simulated process corresponds to an almost uncontrolled process when sampling cycles longer than 40 min are applied."

Jan 1, 2003

By Z. G. Li

The large-scale vibrating screen has been applied widely in coal industry and other industrial areas as a kind of important device. As vibration mechanical device, it works very hardly and works in very bad environment so that the structure of screen is damaged easily. Therefore, it is very important that how to detect the fault of structure as early as possible to make the repair schedule reasonably and economically and to avoid the body hurt and device damage. As a kind of important structure of vibrating screen, the lower crossbeam is the main carrying structure and it is easily damaged, so it is regarded as a researched object in this thesis and it is tested under the load in the laboratory. Based on the test, acoustic emission wave signals can be got-ten by modern acoustic emission testing technique. Then, the ?wavelet packet - energy? from the characteristics of acquiring signals is used as neural network input vector. In the BP network structure design, the design of a hidden layer with variable number of BP network is established. Based on the error by contrast, the best nerve number can be identified in the hidden layer. Through integrated analysis, using Levenberg-Marquard BP study algorithm, network-training errors are relatively small, the acoustic emission signal is used in BP neural network as a pattern of recognition. In Matlab6.5, neural network model identification is created and taking advantage of nonlinearity and the ability of learning and memory of Neural Network, this model is fixed by training structure of network with training samples. The work presented shows that acoustical emission signal processing and research on early fatigue fault diagnosis based on the wavelet and the neural network is viable.

Jan 1, 2014

By D. Hatfield, G. de Jager

"The rapid developments in computer vision and computational resources are creating new possibilities for the use of machine vision systems for industrial control. A number of commercial image analysis systems exist, and research into improved measurements of froth performance is ongoing. An integral part of the implementation of these systems is the validation of the relationship between image analysis measurements and flotation cell performance. This paper discusses the factors affecting concentrate flow and presents the results obtained from one such system with respect to its ability to estimate the flow of concentrate from a flotation cell.The relationship between froth flow speed and the rate of recovery of concentrate from a flotation cell was investigated on two industrial operations, both processing PGM (Platinum Group Metal) bearing ores. Results are presented that show a relationship between froth flow speed and concentrate yield."

Jan 1, 2003

By H. M. Gao

According to the difficulty of dolomite removal from collophanite,normal-reverse floatation process has been adopted in floatation with the use of highly selective collector G-4 and depressant S721. Good indexes of flotation have been obtained with the run-of-mine ore containing 17.96 % P2O5 and 2.31 % MgO being upgraded to a concentrate containing more than 30% P2O5 and less than 1% MgO. The reagent interaction mechanism in low grade collophanite flotation has been stu-died by FTIR analysis and theoretical calculation. The results indicate that the interaction between collector G-4 and collophanite is the result of chemical adsorption in combination with physical ad-sorption with chemical adsorption playing the major role. Depressant S721 adsorbs on dolomite surface to form a water film and effectively depresses the flotation of dolomite and reduces the MgO content in the concentrate.

Jan 1, 2014

By Ahmad Amini, Hadi Abdollahi, Pouya Karimi

Due to detrimental effects of cyanidation process on the environment in gold industry, application of cyanide alternatives such as thiourea are being highly considered in recent projects. In this study, the extraction of gold from poly metal ore, using thiourea was precisely investigated. The representative sample contained 2.5 ppm Au and 160 ppm Ag. The sample was categorized as oxide gold ore, because the main part of its pyrite was changed to iron oxide and hydroxide such as goethite and lepidocrosite. According to mineralogy, the main gangue mineral was quartz. It shows that gold grains are free and interlocked with quartz matrix. Also, the presence of a high amount of silver in free and sulfide forms and also the low content of other sulfide minerals such as base metal sulfides is a remarkable point of these studies. In the gold extraction process with thiourea, there are several parameters that affect the rate of gold dissolution such as concentrations of thiourea as a gold lixiviant and ferric sulfate as an oxidant, pH and size fraction of feed and leaching time. The influence of these parameters on the gold dissolution rate were investigated and optimized. The results showed that the concentration of thiourea is the most influential parameter which could increase the gold recovery to 71% (at 10 g/kg sample). The optimal amount of ferric sulfate was determined as 6 g/kg sample. Also, the optimal levels of size fraction of feed and pH of solution were 88% under 75 micron and 2 as acidity; respectively. Leaching time was 6 hrs. In addition, this sample was leached with cyanide and the optimized values of size fraction of d88=75 microns, pH=10.45, 2500 ppm of sodium cyanide with time leaching of 24 hours were concluded for maximum recovery of gold in solution. Finally, the results of cyanidation tests were compared to the thiourea dissolution after optimizing all affected parameters in cyanidation process.

Jan 1, 2018

By T. Gong

Often plans to increase plant throughput provide an opportunity for optimising plant equipment and operating methods. This was the case in 2005 at TISCO Jianshan Iron Mine, when an increase in production was planned. The thickening circuit had presented a limitation to the plant throughput and operation with poor overflow clarity and underflow density. Following a course of test work by Outotec, a 53m diameter Supaflo® High Rate Thickener (HRT) was selected for the duty. From early stages of operation of the new thickener, the benefits have been dramatic, including: ? Improved tailings underflow density by 9% ? Improved Overflow clarity to less than 150ppm ? Considerably decreased the water and energy consumption as well as operation cost ? Stable and reliable operation This paper looks at this installation as a case study and compares the previous thickener installa-tion performance with the performance of the single 53m HRT.

Jan 1, 2014

By James D. Bittner

Separation Technologies, LLC (ST) has developed a processing system based on triboelectric charging and electrostatic separation that provides the mineral processing industry a means to beneficiate fine materials with an entirely dry technology. The environmentally friendly process can eliminate wet processing and required drying of the final material. The process requires little if any pre-treatment of the material other than grinding and operates at high capacity ? up to 40 tonnes per hour by a compact machine. Energy consumption is low, approximately 1 kWh/tonnes of material processed. Since the only potential emission of the process is dust, permitting is typically relatively easy. In contrast to the other available electrostatic separation processes that are typically limited to particles greater than 75 µm in size, the ST belt separator is ideally suited for separation of very fine (<1 µm) to moderately coarse (500 µm) materials with very high throughputs. The triboelectric particle charging is effective for a wide range of materials and only requires particle ? particle contact. The small gap, high electric field, counter current flow, vigorous particle-particle agitation and self-cleaning action of the belt on the electrodes are the critical features of the ST separator. The high efficiency multi-stage separation through charging / recharging and internal recycle results in far superior separations and is effective on fine materials that cannot be separated at all by the conventional electrostatic techniques. Since 1995, this triboelectric process has been extensively used for the beneficiation of coal fly ash with eighteen separators in place and over 100 machine-years of operation at locations in the North America and Europe. The technology has been also successfully applied to the beneficiation of a variety of minerals including calcium carbonates, talc, and potash.

Sep 1, 2012

By T. Wajima

We tried to convert paper sludge ash (PSA) into zeolitic product with high cation exchange capacity (CEC) through acid leaching. Typically, PSA from incineration of paper sludge contains a high percentage of calcium in the form of anorthite (CaAl2Si2O8) and gehlenite (Ca2Al2SiO7). It is difficult to convert the ash with a high Ca content into zeolites, or at least into more desirable zeolite phases. Acid leaching with HCl was applied to reduce the Ca content to synthesize zeolitic product with high CEC. The raw ash was treated with 1 M, 3 M, and 5 M HCl solution for 0.5~24 hours (the ratio of the ash to volume of HCl solution was 1/4), and then zeolitic product was synthesized from leached ash through the reaction with 2.5 M NaOH solution at 80 oC for 24 hours. During acid leaching, gehlenite is readily dissolved in a lower HCl concentration solution than anorthite. With increasing HCl concentration, the amounts of Ca, Mg, Si, Al, Fe and Ti extracted from the ash increased. Ca and Mg contents were easily extracted from ash than other elements. The contents of Ca and Mg extracted rapidly at initial stage, and then levelled off. The saturation times of Mg and Ca are almost 0.5 h using all concentrations of HCl solutions. After the synthesis from leached ashes, zeolite-A and -P were synthesized from ash leached in 1 M HCl solution, and 3 M and 5 M HCl solutions, respectively, regardless of leaching time. With in-creasing HCl concentration, the Ca content eluted from the product decreased, due to the removal of Ca via acid leaching before the synthesis, while the Na content eluted from the product increased to 3 M HCl and then decreased, which was almost similar to the CEC of the product, due to the ion exchange of Na-type zeolitic phase in the product. The change of zeolite phases in the product and the CEC of the product depend on the concentrations of Si and Al in the solution during the synthesis. The highest CEC of the product is about 220 cmol/ kg, which was synthesized from the ash leached in 3 M HCl solution.

Jan 1, 2014

By K. Gonçalves

One of Vale?s sponsored research project is aimed at the implementation of a practical scale-up procedure for flotation. In this context, detailed flotation kinetics characterization is of critical importance. This work presents the results of a campaign aimed at characterizing flotation kinetic parameters with respect to particle composition. MLA analysis was carried out for 40 narrow-sized iron ore particles with known flotation time from a controlled flotation kinetic test. The iron ore sample studied (59% hematite and 41% quartz) comes from a mine in the southeast of Brazil and the type of reagents applied are the same as used in the plant. For the reagent conditions tested, the overall rougher concentrate (sink) yielded 79.1%, pure quartz and hematite recoveries to the froth were 56.0% and 4.8%, respectively. The results from the kinetic tests show that the flotation rate of the particles doesn?t vary much (~0.03s-1) with composition and that the fraction of floatable particles in each grade controls the separation action. The results show that the rate of flotation is controlled by transport and that the selectivity is controlled by the fraction of floatable particle of each phase.

Sep 1, 2012

By Ventsislav Stoilov, Angel Angelov, Ivan Korolev, Antti Remes, Todor Pukov, Stoyan Gaydardzhiev

"The process modeling and simulation studies aim for better process operation and favorable environmental impact. The objective of this work is to set up a simulation model of the Assarel copper flotation circuit for planning and optimization of the process with the aim of increased metal recovery. The model is parameterized based on laboratory flotation tests of ore samples from the Assarel mine together with mineralogical studies by X-ray diffraction (XRD) and Mineral Liberation Analysis (MLA). A combination of several techniques allows reliable identification of mineralogical composition of the selected samples. The changes in the proportion between sulfide minerals in various products along the circuit have been also documented. Further, this information is used in the simulation model and in data reconciliation procedures for establishing mass balance. The simulation accuracy is studied by comparing the simulations with the plant survey based mass balance. Constructed simulation model can be used to run alternative process scenarios. As an example, the flotation circuit performance with different reagent regimes is simulated based on data from batch flotation tests. Two reagents were considered for this purpose, dithiocarbamate-based one and xanthogen formate/mercaptan blend. It has been revealed that these reagents do not have the same influence on the selective flotation. The one improves flotation of gold and overall recovery but without notable selective action. In contrast, the other showed better selectivity towards copper, rejecting more gangue and lowering gold recovery. The model is also applicable for process optimization studies with different feed compositions, flowrates and circuit configurations. INTRODUCTION In the pursuit for elevated technological indicators, finding an optimal set of process parameters fully utilizing the potential of the equipment is a key factor to success. Over the past decades, there has been a substantial development in flotation circuit optimization through performance benchmarking using metallurgical modelling and steady-state computer simulation. Practical simulation engineering tools are based on experimental data obtained from laboratory tests and from plant surveys and operation data. With the help of flotation models, it is possible to study grade-recovery response with different feed compositions and throughputs, and with various cell-operating parameters, as well as to evaluate and design different flowsheet configurations. Outotec’s HSC Chemistry® software, which incorporates simulation and mass balancing modules alongside with several other tools, can assist with this optimization (Mattsson et al., 2015)."

Jan 1, 2018

By R. X. Li

The overall flow-sheet of producing chromium (III) sulfate is described in this paper. The suitable conditions of each process such as sintering, leaching, aluminum removal, reduction, and de-composition conditions were experimentally studied. The results show it is reasonable to produce chromium (III) sulfate with the flow-sheet pointed out in this research work. The final product is Cr2(SO4)3 solution contained 150~250g/L Cr.

Jan 1, 2014

By M. Kalicinski, M. Lyssyy

"Access to information is a key component for making improvements to any process. This is particularly true for all aspects of the iron mining and steelmaking process. The ability to make rapid control decisions can significantly influence process outcomes, including ensuring product specification, mining quality, transportation limits, upgrade factors, waste bypass and direct shipping, among many others. While traditional laboratory methods provide feedback for such processes, having access to analysis results in real-time can lead to positive reactive and predictive control decisions to be made rapidly, leading to significant improvements throughout the process. Scantech has been designing, manufacturing and supplying technological products to the minerals industry since 2002 to enable the availability of such real-time information to a mine or plant, with the benefits being enjoyed by a wide range of operators. This paper provides a summary of the available technologies used in the iron ore and steel industries, as well as providing case studies of their use in African and Australian iron ore and European steel, as well as a description of the potential benefits of a range of analysis equipment.INTRODUCTION Access to information is critical for any process, and is a fundamental component for making process control decisions. In order to yield effective processing outcomes, it is important for that information to be readily available, preferably as quickly as possible, and to be as accurate as possible. While speed and accuracy are often traded off against each other, there are numerous technologies available in a processing environment that allow for both rapid flow of information and a high level of accuracy. The use of on-belt analysis equipment has a long trusted history of use in a number of mining and processing environments and industries, providing information such as elemental composition and grade of conveyed materials, moisture content, waste proportion and energy information. Australian company Scantech has been a provider of such equipment since 1981, and has become an industry leader in both the supply and development of on-belt analysers across a range of industries."

Jan 1, 2018

By ?. Kostadinov

Theoretical study of the behavior of grinding medium presented by TBP (tetraballpebs) was conducted by computer modeling of the position of grinding medium at different speeds and different drum fill factor. For the modeling were used known equations of motion derived for the ball load. Algorithm was created by SolidWorks software, allowing determination of center of gravity of the load in the mill and energy for grinding. These results were compared with similar results obtained by ball grinding medium. The capabilities of both grinding media are demonstrated by graphics under the following conditions: 1.Equal dimensions of the experimental model of the mill; 2.Equal mass of the grinding loads; 3.Comparison of grinding bodies with the same number, mass and density. Keywords: simulation, behavior, grinding medium, balls, tetraballpebs

Sep 1, 2012