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By T. B. M. Himawan

In this study, effect of thiosulphate and oxidation using oxygen were studied in arseno copper ore flotation. Single mineral study of chalcopyrite and tennantite in regard to the aforementioned techniques was also studied. Zeta potential, XPS, contact angle and floatability of single minerals were conducted for each treatment to understand the mechanism. It was revealed that the separation is best conducted in alkaline condition at where there will be interaction between thiosulphate and the mineral surface as well as the formation of hydroxide species in the oxidation using oxygen. From zeta potential of both thiosulphate and oxidation conditioning, it can be found that the reactivity of tennantite is much higher rather than chalcopyrite resulting higher rate of depression on both techniques as shown from contact angle and floatability of each mineral after treatment. XPS spectra confirmed qualitatively and quantitatively the existence of species responsible for the depression of each conditioning techniques. As for the copper ore flotation test, it is the oxidation using oxygen provides best performance after 60 minutes of oxidation. Keywords: tennantite, chalcopyrite, arseno copper ore A, thiosulphate, oxidation using oxygen

Sep 1, 2012

By N. T. Beukes, W. Banda

Recovery of Co from slag is a recent advancement in the extractive metallurgy of nonferrous metals. In this study a DC arc technology at laboratory scale has been applied to investigate the selective recovery of Co from slag, under three different flux types with an emphasis on influencing the activity of FeOx, SiO2 and CoO in the slag. It is known that reduction of slag by carbon is only up to a certain level after which, the recovery will depend on the chemistry of the slag, hence the need to modify the slag chemistry. Two power settings were employed to induce higher temperatures and aggressive agitation. The results were interpreted by comparing how much Co and Fe was in the slag and alloy. TiO2 reduced the amount of Fe in the product alloy compared to when CaO and CaF2 were used. The change in power did not seem to have had a major effect on the recovery although the amount of material lost to flue dust was more at a higher power rate.

Jan 1, 2003

By H. Lieberwirth, M. Hesse

"Selective comminution (SC) is beneficial for the treatment of primary raw materials, especially if it is utilized in the pre-concentration process. Pre-concentration processes are applied in mineral processing to relieve subsequent processes and to achieve a higher efficiency. SC is also a promising method for the treatment of low-grade ores and waste dumps. With SC, various components can be separated such as valuable minerals from waste, ore from wall rock and different ore varieties within a deposit. SC is a property of a comminution system and leads either to a preferred crack propagation in one component (called preferential breakage) or to a preferred crack propagation along the grain boundaries (called interfacial breakage). SC results from different comminution behavior of various components in the feed material. For mechanical comminution, the preferential breakage seems to be the most important case of SC. Hereby SC generates only the difference in the particle size which can finally be used as a sorting parameter. A sorting process which uses SC depends on three parts: the feed material, the comminution machine and the separation machine. The feed material defines the potential for SC. Differences in properties like strength, toughness and density which are related to comminution are often used. The comminution machine has to exploit this potential. The extent of the exploitation can be influenced by the machine design, material and operational parameters. After SC, the various components are still combined in the product. So ultimately, a separation machine is needed. At preferential breakage, a simple screening machine can be used. The basics about SC will be presented at first. This contains relationships between material properties, the kind of loading in the comminution machine and the SC effect. These basics can be used for example to exploit a potential to SC for a pre-concentration step or to avoid the SC for a higher efficiency of subsequent processes. Based on recent investigations with impact load, the influence of the important parameters compressive strength, density, particle size and impact velocity to the SC will be shown, using examples of lead-zinc ore comminution and fluorspar processing."

Jan 1, 2018

By S. P. Das

Tumbling mill is an important unit operation in a mineral processing industry whose operation needs to be understood to make it an energy efficient unit. One of the important mill parameters is the impact spectra generated by collision of the moving charge mass on the mill shell. This process also generates mechanical vibration on the mill shell and propagates to the plumber block of the mill. In this work, we tried to understand the impact spectra by using different minerals such as Banded Hematite Quartzite (BHQ), Hematite and Quartz as mill feed of a semi-autogenous (SAG) mill. The said mill is of 1000 mm diameter and fitted with a force sensor on the mill shell and a vibration sensor on the plumber block. The analysis of the impact spectra was done by taking into consideration the peak impact force above a certain threshold value. It clearly shows that the impact force decreases as the particle size become finer irrespective of the mill feed material. This can be used as an effective tool by the mill operators to have an understanding of the mill product size reduction. The mechanical vibration tapped by a tri-axial accelerometer was analyzed by power spectral density analysis. The vibration signal analysis shows the variation in the power spectrum magnitude both at lower and higher frequency. It also shows inconsistency in case of BHQ where it shows a significant decrease in vibration at lower frequency and increase in vibration at higher frequency. Therefore, the impact spectra analysis is a better method compared to vibration analysis in understanding the mill product size reduction.

Sep 1, 2012

By Sunil Tripathy, Y. Rama, Srinivasulu. A., Amit Ranjan

Process improvements in an operating plant are always challenging. Mineral beneficiation plants based on gravity concentration techniques need continuous evaluation and monitoring of its processes for getting maximum recovery and better grades. But, in an operating plant it is very difficult to control all the parameters due to numerous reasons such as unsteady operation, fluctuation in the quality of run-off-mine ore, overall flow rate etc. For better understanding of the beneficiation circuit, it is necessary to evaluate the critical operating parameters which affect the performance in terms of grade, recovery and throughput including losses of valuable materials into tailing. Accurate data collection and proper data interpretation followed by making necessary change which is implementable in an operating plant play very critical role in performance of the circuit. In case of gravity operated beneficiation circuits of chrome ores where the quality of the feed and physical parameters varies continuously, the operators are required to modify the critical operating process parameters on continuous basis which is very difficult and tiresome. There are many causes of the data variability, including both error (sampling and assay), and real variation in performance due to changes in ore mineralogy, operating conditions and other factors. In this article, attempts made to evaluate the performance of ultra-fine beneficiation circuit in terms of silica reduction in the concentrate of chrome ore beneficiation plant (COB), India are discussed. The approach adopted and practical problems encountered during the study were also discussed. Results obtained from plant audit based on the above methodology has shown that SiO2 content in the concentrate can be reduced to <4%.

Jan 1, 2014

By R. Shiva Kumar, G. Sreedhar, S. Sharma

Some of the Indian origin iron ore deposits located in Bellary, Karnataka province are having peculiar characteristics of Iron ore deposits (Hematite) having Iron above 64% and 30-40% lump (-30+6mm) recovery which are not suitable to use in blast furnace due to not meeting the specification of Tumbler Index and Abrasion Index. In general for high grade Iron ores, process flow sheet involves crushing and screening (dry/wet). In the contest of high grade Iron ores located at Bellary sector of Karnataka state in India, lump generated from this process could not attain the required physical properties (Tumbler Index, Abrasion Index) and metallurgical properties , even though the grade of the lump ore is above 64% Fe. Washing techniques like Drum scrubber and Log washer play major role in improving the metallurgical properties of Iron ore lumps by removing the light and hard layers of clay, silica coated over the lumps. In this study the effects were compared of drum scrubbing and log washing on iron ore lumps. It is found that by incorporating simple washing technique i.e. drum scrubbing or log washing, Tumbler Index of Iron ore Lumps could be increased from 74% to 78% which is acceptable for use in Blast furnace. From the Drum scrubber and Log washer tests, it is clear that Log washers have an edge over Drum scrubber in removing hard coated clay on surface of Lumps. This simple washing technique facilitate us to utilize the lumps directly in blast furnace and eliminate the unnecessary crushing and grinding of the ore so as to meet the specifications of Sinter fines and pellet feed.

Jan 1, 2014

By Stephen J. Harker, John Knights, Randolph A. Pax, Glen A. Stewart

"Mineral samples were obtained from different stages of a mineral processing circuit used to extract the copper and gold rich mineralogical phases. The aim of this work is to characterise the quality of the samples at different stages of processing. The samples were taken of the head grade, tailings, cyclone overflow and the final concentrate.Characterisation of the samples was determined using Cu-Ka X-ray powder diffraction and Fe57 Mossbauer spectroscopy. These measurements will be presented and discussed in terms of the enrichment of the ore, showing the removal of magnetite and quartz through the processing, the final concentrate being rich in chalcopyrite and pyrite. This data also shows the utility of Mossbauer spectroscopy to provide mineralogical phase information directly.Mossbauer spectroscopy is a tool to determine the material phases of a sample. It is a nuclear based technique which measures the amount of attenuation of a narrow Doppler shifted source energy as it passes through a sample. The attenuation depends on the amount of resonantly absorbing material in the nuclear radiation path from the source to the detector. Synchronous detection of the doppler shifting velocity and the nuclear radiation count gives a Mossbauer spectrum. By convention, the energy axis of the Mossbauer spectrum is displayed in units of velocity.Figure 1 shows Mossbauer spectra obtained for a sequence of samples throughout a processing plant. These spectra show the removal of magnetite and the concentration of chalcopyrite and pyrite. Optical microscopy results indicated a significant component of bornite not witnessed with Mossbauer spectroscopy. Closer examination showed that optical microscopy assays over estimate the bornite component."

Jan 1, 2003

By P. A. Harvey

Previous studies have reported that inorganic electrolytes can enhance floatability of coal. The research has shown that the enhancement, if any, is highly dependent on changes in solution pH, type of electrolyte, and electrolyte concentration. The reasons for this are still not clear. In this study the floatability of coal particles in mono and divalent salt solutions was investigated. The zeta potential and hydrophobicity of the coal was measured experimentally, and a modified Hallimond tube was used to determine the floatability of coal particles by single bubbles, where the collision efficiency was equal to unity. The experimental information was used in conjunction with the Hogg-Healy-Fuerstenau equation to quantify the electrical double layer interaction. It was found that for low electrolyte concentration (less than 0.1 M) solutions the flotation recovery of coal particles was less than that for distilled water, and decreased with increase in concentration. Conversely, at electrolyte concentrations above 0.1 M, flotation recovery increased with increasing concentration (Figure 1). Both of these results are consistent with previous observations, but are inconsistent with expectations when considering the possible influence of electrical double layer interaction. Modelling of the system indicates that the electrical double layer is compressed with increasing electrolyte concentration, resulting in an increase in flotation recovery due to a diminishing of the (electrical double layer) repulsion between the bubble and the coal particles. Moreover, for electrolyte concentrations above about 0.1 M the electrical double layer is completely depressed and would have little further influence, if any, on the flotation process. Therefore, the electrical double layer interaction is not the principal determining factor for the flotation of coal in electrolyte solutions.

Jan 1, 2003

By I. N. Babich

"Complex technological problems associated with the processing of mineral raw materials require the search and development of new means and ways of thinking. At present, computer cognitive graphics (CCG) are one of the most actively developing areas of new information technologies. The aim of the study was to optimize the cycle of technological evaluation of ores at all stages of geological exploration of deposits on the basis of analysis of geological sampling data using CCG. A new approach has been developed that facilitates optimization of the whole cycle of subsoil exploration. At the gold ore deposit, the results of the geological sampling data were processed by the method of constructing the CCG in the form of a histogram showing the frequency of gold extraction and the average amount of its content. Significant peaks of the metal content in the ore, exceeding the level of the average content in the ore by tens of times, have been revealed. Graphical interpretation of the parameters of mineralization reflects the uneven nature of its variability, which indicates the presence of large, rarely occurs of gold in the ore and the need to conduct studies on a sample of ore of greater mass than for ores with tiny gold. On a sample of 50 kg gold-quartz ore studies were carried out on gravity enrichment. The maximum size found in the gold concentrate was 0.07 mm. In the course of integrated tests in a gravity concentrate, gold particles up to 3 mm in size were found, which predetermined the need to include the operation of gravity before flotation. A new approach to subsoil research is protected by a patent (RU 2620823).The technological problems that arise before the researcher associated with the processing of resistant ores require the exploration and development of new means and ways of thinking. New problematic situations on complex mineral and raw materials objects are practically not amenable to resolution by existing methods. Integration of industrial and information technologies is necessary. At present, computer graphics (CG) is one of the most rapidly developing areas of new information technologies. For example, in scientific research, including in fundamental research, the accent from the illustrative function of CG (the visualization of what is already known) is increasingly shifting towards the use of computer cognitive graphics (CCG) tools (Bashlykov, 2016). The function of the CCG is to obtain a new knowledge with the help of a graphic representation - a cognitive image or at least to promote the intellectual process of the logical acquisition of this knowledge. In this study, cognitive images are used to graphically represent the distribution of valuable components in the bowels of the deposit, characterizing the state of mineral-raw materials."

Jan 1, 2018

By S. Kelebek, A. Khan, J. Caceres, D. Beckett

"Pyrrhotite in nickel-copper sulphide ores is nickeliferrous and intimately associated with pentlandite. Due to its low nickel content, pyrrhotite rejection is an important step in processing of these ores. In our laboratory, various reagents were investigated for their effect on pyrrhotite depression. Among these, a combined use of triethylenetetramine and sodium metabisulphite was found highly promising.The work described in this paper has two parts. The firs part is a summary of results obtained on process samples from the pyrrhotite rejection circuit at Falconbridge’s Strathcona Mill. The second part involves simulation of the circuit performance based on the reagent conditions used in the experimental work and the concept of split factors.Two sets of reagent conditions were evaluated. The first one involved baseline conditions, simulating the current reagent performance. The second one simulated the impact these new reagents can have on the circuit performance.The simulation results obtained under baseline conditions indicated a good agreement with the current circuit performance (Figure 1). The simulation results suggest that at practically the same pentlandite recovery and tailing grades, the circuit concentrate nickel grade can be doubled through effective pyrrhotite rejection by these new reagents (Figure 2)."

Jan 1, 2003

By H. Z. Kuyumcu

Coking of coal blends using high volatile coals with poor coking abilities to produce a high quality coke for blast furnace application can be achieved by compacting the coal blend prior to the carbonization process. Here densification up to a relative material density of 80 %, i.e. a compact density around 1100 kg/m3, has proven to be advantageous. Coal is compacted by stamping, if the so-called stamp charging process applied. Compacting of the coal by pressing is practised in case of the cokemaking with so-called heat-recovery ovens. Stamped and pressed coal cakes require over the cake volume uniform high density and mechanical stability. Besides the aspects of the coal selection, the efficiency of the process is mainly determined by the operating parameters compacting time and compacting energy for coal cake making. At the Department for Mechanical Process Engineering & Solids Processing of the Technical University Berlin the two sub-processes of densification and strengthening during stamping and during pressing are theoretically and experimentally investigated using specially developed lab-scale compacting test units and a strength test device. Describing cake density in terms of coal properties for a given coal and measured compacting energy input then leads to a compacting equation with the so-called Stampability as the integral model parameter for the stamping process. For the pressing process the cake density can be calculated with the measured compacting pressure and the Compressibility factor, respectively. Investigations were carried out to provide evidence of a significant influence of coal type, coal surface moisture, coal granulometric and mechanical properties on the densification process. The overall objective of the work is to establish a comprehensive mathematical model on the compacting behavior of large coal bulk quantities and the optimization of the compacting processes by stamping and by pressing. Keywords: coal compacting, agglomeration, stamping, pressing, cokemaking

Sep 1, 2012

By Peter Ay, Harry Pempel, Satya Narra, Mike Müller, Jens Markowski

"Within the next few years major changes in mobility are expected. Increasing numbers of electric powered cars, electrobikes and E-Scooters define the transport sector. Recently lithium based traction batteries as storage medium have led into matrurity of series production combining high electrical efficiencies with low weights and compact dimensions. Due to the relatively young development with lithium batteries utilization, only few investigation were conducted regarding their recycling. Conventional battery recycling processes can not be applied due to differences in design and chemistry. So an automated disassembly and processing procedure for lithium traction batteries has been developed in the R/D-project ""Li-WERT"". Instead of complete smelting of the batteries without pretreatment, an automated disassembly and specific treatment of the material streams was realised, adjusted to the needs of the subsequent recovery technologies. A higher quality, with reduced expenses for the separation of fine-grained or fused material mixes, can be obtained for the individual components. The automated disassembly using an industrial robot significantly reduces dangers for the operating crew. The selective disassembly and beneficiation allows full recovery of the fractions. The batteries will be disassembled to cell level by the industrial robot. Anodes, cathodes, and separation layers are isolated and processed. The technology is designed, that no waste is generated for disposal. The pelletised cathode coating and the other separated metals (stainless steel, copper, aluminum) can be used in respective metallurgical plants. Circuit boards and plug contacts are also coveted secondary raw materials for reuse. The process is modular and offers high flexibility, e. g. for new battery types/ sizes by quick adjustment of the robot and tool change. Adaptation to other cathode materials (e. g. Li[FePO]) is possible. After finishing the R/D-project, a pilot plant for demontage was realised in 2013."

Jan 1, 2014

By Yong Liu, Peng Qian, Shu-Feng Ye, Shao-Jun Chu, Pei-Wei Han

"Chromite with a low mass ratio of Cr to Fe (Cr/Fe ratio) was treated by the carbochlorination method using solid chlorinating agent (MgCl2 and CaCl2) and carbon in the present paper. The results showed that iron could be selective removed mainly in the form of FeCl2. The removal of iron was indirectly, which consisted of the decomposition of solid chlorinating agent to release Cl2/HCl and the carbochlorination of FeO•Cr2O3 by Cl2/HCl and C. The Cr/Fe ratio increased as increasing temperature from 700 ? to 900 ? in air atmosphere, while the tendency was opposite in N2 atmosphere. The removal efficiency of iron by CaCl2 was better than that by MgCl2. At last, a new pelletizing process was proposed to treat fine chromite with a low Cr/Fe ratio based on carbochlorination method, which could produce the high quality roasted chromite pellets with higher Cr/Fe ratio and compressive strength. INTRODUCTION Chromite is mainly used for the production of ferrochromium. A high Cr/Fe ratio (>2) of chromite is usually required to meet the technical specification of ferrochromium.(Gasik, 2013) Attentions have been attracted to the economic and efficient methods for the recovery of chromium from lower-grade ores as the higher-grade ores become depleted. However, the Cr/Fe ratio is difficult to improve through the conventional beneficiation methods (such as gravity concentration, flotation) due to the spinel composition, although beneficiation methods could increase the metal content of chromite ores by removing gangues.(Nafziger, 1982) The main industrial mineral of chromite is (Fe,Mg)O•(Cr,Al,Fe)2O3, which belongs to spinel magnetite.(Liu, 2013) Iron should be selectively removed through the structural dissociation of spinel to increase Cr/Fe ratio.(Nafziger, 1982)"

Jan 1, 2018

By Kazimierz Trybalski

"Simulation methods have a big potential in the studies and analyses of complex technological processes and schemes. The simulation method used jointly with flow diagrams and related transmittance models allows describing and analysing dynamic characteristics.The paper presents results of simulation analysis of dynamic characteristics of ore dressing system, called closed circuit mill-classifier-mill. Such systems are widely used in ore processing plants. The system was analysed as a typical system with material feedback, to establish its dynamic characteristics.Flow diagram conforming to the technological scheme is presented in a figure. Transmittances shown in the scheme are defined as follows:GMP - transmittance of rod mill,GP, KZ, GW, KZ - transmittances of overflow and underflow streams of spiral classifier, respectively,GMK - transmittance of ball mill,GT - transmittance of underflow stream from classifier to ball mill,GU, MP, GU, MK - fraction transmittance of outflow streams of rod and ball mill, respectively, summed up at classifier input.Taking into account, in base of carried out analysis the transmittance forms of individual system elements. The calculations are based on numeral forms of transmittances of individual blocks, defined through industrial experimentation.Step input function to rod mill was assumed to be a step of mass ore flow rate to the mill. Responses are defined as product densities.This figure demonstrates the way of input signal transmission by consecutive elements of the system and shape of these elements' responses. It can be noticed that step signal undergoes gradual change from the stream of the first order to those of higher and higher orders as a distance from process leading edge increases. Simultaneously, the impulse signal is subject to systematic smoothing and decay. From the technological point of view, the most important is response stream in point 5 (on the above figure) that characterises classifier overflow, which is a final product of this system."

Jan 1, 2003

By Güven Önal, Zeki Dogan, Neset Acarkan

"In general, the processing of glass sand may involve comminution, washing, wet classification and attrition scrubbing. Additional processes may include magnetic separation, flotation and leaching in various combinations.Yaliköy sand dune deposit is located near to Istanbul on the European side by the Black Sea coast. The reserve of deposit is around 70 million tons. Iron content of Yaliköy sand dunes is 0.48 % Fe2O3 and not suitable for glass manufacture. The iron content of glass sand should be less than 0.15 % Fe2O3 for window glass manufacture and 0.05 % Fe2O3 for glassware. In this study, it was aimed to produce glass sand with less than 0.15 % Fe2O3 for window glass and with less than 0.05% Fe2O3 for glassware manufacture from Yaliköy sand dunes. A representative sample with a weight of 200 kg was taken from Yaliköy sand dunes deposit through opening small pits.• Mineralogical studies have shown that iron is present in three forms:• Hematite, limonite, clay and iron silicate minerals such as epidote and garnet occur in free form.• Quartz grains are coated by hematite and limonite.• Iron is also present in the cracks of quartz grains.Free iron minerals such as hematite and limonite and silicate minerals were subjected to magnetic separation and flotation for removal. Iron coatings were tried to be removed by scrubbing and leaching. Iron removal in the cracks of quartz grains was attempted by grinding and leaching.Under optimal conditions, sand concentrate with 0.38 % Fe2O3 was obtained by means of high intensity disc type magnetic separation. Grinding and scrubbing were applied to see the effect of size reduction and attrition at room temperature and 90 ºC, by using non-magnetic fraction. Sand concentrate with 0.13% Fe2O3 was obtained at 90 ºC in this test.Sand sample which was previously ground to minus 0.5 mm and scrubbed, was floated by using sulphonates as collector. After flotation tests, sand Concentrate was obtained with 0.11 % Fe2O3.The optimum iron removal was achieved by H2SO4 leaching at 90 ºC depending on acid concentration and leach duration in static, percolation and agitation leaching. Agitation leaching was done by the use of mixer at 600 rpm, 50% solids and leach duration was 15 minutes."

Jan 1, 2003

By A. J. Lynch, L. Ergun, M. Oner

"A research program on modelling cement grinding circuits has been in operation at Hacettepe University, Ankara, for four years. It has concentrated so far on tube mill and air separator grinding circuits for cement clinker, with emphasis on plant sampling surveys, including axial sampling inside the tube mills. The methodology is to use plant data to build the models and to supplement this by laboratory data where necessary, for example the determination of breakage functions. The plant data come from comprehensive sampling surveys and so far 33 surveys of clinker grinding circuits have been carried out in 9 plants. The operating conditions have been• mill sizes – 3.2 to 4.8 metres diameter and 8.5 to 15 metres long,• mill feed rates – 46 to 158 tonnes per hour,• air flow through mills – 25000 to 125000 cubic metres per hour,• cement clinker work indexes – 10.3 to 18,• separator sizes – 2. to 3.1 metres diameter,• separator feed rates – 132 to 689 tonnes per hour,• separator speeds – 12.3 to 21 metres per second.The ball mill model is Whiten’s perfect mixing model and the separator model is the Tromp curve with a fish-hook. This paper emphasises on the importance of calculating the breakage rates and the discharge functions with three case studies at five different circuits which were selected for discussion because they show how particular features of circuit operation can be included in the general models. Size distributiongraphs are used to illustrate every aspect of the discussion.In case I the special emphasis on calculating the breakage rates and discharge rates separately is given in a high pressure grinding roll-ball mill-separator circuit. The tonnes of each size fraction in the mill and the calculated values of R/D, D and R are determined. The values of R per mw are also given to allow comparison with mills of other sizes. The circuit allows the comparison of the static type (V Sep) and dynamic type separators (SKS). Comparing the reduced efficiencies shows that the dynamic separator is slightly more efficient than the static one.In case 2 data are given from two compartment tube mills having the same diameter and the motor power but different ball size gradation. The breakage rate particle size variation of the second chamber of two mills indicate that having finer ball size distribution causes higher breakage rate values."

Jan 1, 2003

By Willis Forsling, Prabhakar Swarna, Hanumantha Rao Kota

"The solubility of wollastonite and its Hallimond flotation behavior as a function of dodecylamine concentration and pH are examined. The flotation response is characterized by adsorption and surface energy in the presence of amine. The methods of UV-Visible and FT-IR spectroscopy for adsorption and sessile-drop contact angle for surface energy estimation are employed.The results of wollastonite dissolution clearly showed its non uniform dissolution. The surfaces are depleted with calcium ions and became rich in silicon within 10 min of flotation time. Maximum flotation of wollastonite corresponds to a half monolayer coverage of amine, which is substantiated by the surface energy parameters as shown in figure 1."

Jan 1, 2003

By Dilip. Makhija, Asim. K. Mukherjee, Tamal Ghosh, Abhay Patra

In India around 15-20% of Run of Mine (ROM) from any iron ore deposit reports to slime dams as byproduct of iron ore beneficiation process. The proportion of iron ore slime to ROM will increase in future with higher proportion of lean grade ores in ROM. Furthermore, tonnages of iron ore slime will also increase with increasing demand of iron concentrate. Presently, this slime is stored in the dam in the absence of beneficiation technology. A beneficiation flowsheet has been developed at Tata Steel. This process produced concentrate of 2.2% alumina with 40 % yield from slime of 7-9% alumina. The iron content in the reject will be less than 40% thus adhering to the regulatory norm. Pilot scale study show waste from slime beneficiation is a good raw material for making a variety of building materials. Waste from slime beneficiation also has soil amendment properties. Pilot scale studies show productivity of rice increased when the waste of slime beneficiation process is mixed with soil. On commercialization of this zero waste technology slime generated from the iron ore washing plant will be completely used. In this paper the result of the pilot scale studies on slime beneficiation and utilization processes towards soil making and making of building materials are discussed in detail.

Jan 1, 2014

By Markus A. Reuter, Albert Scholte, Ewoud V. Verhoef, Gerard P. J. Dijkema

"A dynamic, interactive map has been developed of the life cycle of a number of metals, from mining through to minerals processing, metal production, product manufacturing, recovery and waste management. Whilst the existing metal process network and waste management infrastructure provide substantial scope for (product) design, these also limit change because of the strong path dependency of industry and infrastructure development. The metal production network is complex, as it consists of an interconnected and integrated system that incorporates multiple production routes for a spectrum of metals. More often than not, the production or recovery of a single metal is related to or dependent on the generation or recovery of another. The effects of these other metals is of great importance. In order to realize the potential economic importance of impurities, research and development have integrated the processes of copper production with those of lead and zinc, and connected the processes to those of among others silver, bismuth, tin and platinum group metals (PGMs), for example. The recovery of these elements from the interconnected circuits is extremely complex, as most of the elements must be circulated between two or more circuits before they are concentrated enough to make their extraction possible, and their recovery as a compound profitable.From such a system’s perspective, it can easily be seen that a complication for solid waste management has arisen through the development of products (consumer goods) that bring together metals that are not linked in natural resources. As a consequence, many of these materials are not compatible with any process in the metals production network that was developed for the processing of primary, natural resources, optimized for the processing not only of the primary metal but also for all mineralogically associated minor valuable and harmful elements. The formation of large or complex residue streams or undesired harmful emissions then inhibits processing and recovery of said products at their end-of-life. Another complication is that any change to the system (in metal production, SWM or product design) affects the system configuration. Due to the changing demands for metals as a result from the changing products made from the metals for example, the relationships between the processes in the interconnected metal production systems change. This affects both the demand for old scrap (required amount and grade) from waste management, and the environmental profile of the metals. Preferably, therefore, product designers, waste processors and metal producers must cooperate to realize optimal metal recovery in processing discarded consumer products."

Jan 1, 2003

By M. Pischtschan, S. Belz, M. Perrucci

In High Pressure Grinding Rolls (HPGR), the material grinding takes place between the fixed and floating rollers. In this regard, the rollers start to wear over a period of time, which is impacted by for e.g.: ore characteristics, operating pressure, feed material size and non-uniform feed presentation across the roller width. HPGR operational experiences have shown that the rollers do not wear at the same rate. This differential wear rate over time leads to differences in the tangential speeds of the rollers, causing an uneven gap between the fixed and floating rollers in relation to the material. This unwanted but extremely common situation results in a less effective grinding process due to the fact that the slip between rollers is not optimal. As the rollers wear profile increases, the roller with smaller diameter starts to wear further, deteriorating the comminution efficiency up to a point where operators have to stop the HPGR to replace the rollers. Since the wear rate of the rollers is not equal, the replacement of the same cannot be properly planned so that their life-time are fully utilized. In this paper, a dynamic load share control with the use of ABB’s variable speed drive system is proposed, which provides the possibility to the HPGR operator to impact the roller wear in such a way that it equalizes the wear rate to a certain extent and extends the roller life time. Called RollXtend™, this solution includes a load share factor which can be parameterized based on the wear measurement performed manually during maintenance procedure. Additionally, this paper describes an automated load sharing concept based on a non-invasive wear measurement method. The partial results of the technology trial in a copper/gold mine are presented, which aimed at detecting stud damage and estimating the real rollers profile throughout their life time. The final objective of the pilot project was reduce the amount of planned and unplanned downtimes of the HPGR by increasing the rollers life time and avoiding catastrophic stud damages.

Jan 1, 2018