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By M. Mezzetti, E. Anders, O. Popov, P. Hoske, H. Lieberwirth, M. Voigt

"The material breakage induced by high energy electric discharges is known in general as electric impulse technology. This technology can be used for processing solid materials, such as rocks and ores. The electric impulse technology has been around for about 60 years, originally developed and intensively investigated by Russian researchers. However, the application fields have been limited to research and laboratory scale projects. Currently, there are new attempts to transfer this technology into practical industrial applications. Practical examples include drilling of deep geothermal wells with an electric impulse driven drill-head. Traditional comminution implies high energy consumption, hence, high costs. The Electric Impulse Technology is interesting for comminution of mineral and complex ores since it could allow improved recovery and energy reduction, thus resulting in significant savings. Another advantage is the dust free processing, which contributes to make minerals processing environmentally friendly. The use of electrical comminution for processing complex ores is investigated within the ELIZE research project funded by the BMBF (project No. 033R161 A) and industrial partners. The main objective is the development of an industrial scale electrical comminution machine. The first development stages include the investigation and characterization of the electric impulse induced weakening on rocks and ores. The characterization results of the preliminary trials at the microstructural scale on granite, skarn and greisen will be presented and discussed in this article. INTRODUCTION The pioneer work in the area of electric impulse technology was conducted by Russian researchers about 60 years ago [1]. While there have been some successful attempts to transfer this technology into practical applications, such as rock processing [2], laboratory processing of mineral ores [3–5], recycling [5] and geothermal drilling [6–9], the jump into practical industrial large scale application has not been accomplished yet. The Institute of Mineral Processing Machines of the TU Bergakademie Freiberg currently leads a project which can be seen as the next logical step for the technology transfer to industrial applications, namely, the development of continuously operating complex ore processing machines based on the electric impulse technology."

Jan 1, 2018

By G. N. Jadhav

In India, bauxite deposits are concentrated in Central India, Western Ghats and Eastern Ghats. Bauxites from various regions in Gujarat were identified during the present investigations of geochemical mapping. Different types of Bauxites samples were collected from Kachchh, Jamnagar, Porbunder, Junagarh, Bhavnagar and Amreli areas of Gujarat state and were studied in detail for their geochemical signatures to plot the data on Geochemical map. Raw bauxites were characterized by using powder XRD, XRF, ICP and optical microscopy techniques (with the help of Model microscope having both transmitted and reflected light setups) and were later examined to grade their quality. Most of the bauxites from Kachchh region were of high-grade (gibbsitic) type; while those of Sourashtra region were of low-grade (lateritic / calcitic) types. Most of these bauxites were either of ferruginous/lateritic or of calcareous/calcitic types. Based on the mineralogical composition, such as gibbsite, hematite and/or goethite, Kaolinite and calcite minerals present in particular bauxites, the deposits were graded. Finally, the Geochemical mapping of Bauxites for Gujarat region was prepared and discussed.

Sep 1, 2012

By Zhazira Baltabekova, Nina Lokhova, Arailym Dukembayeva, Madali Naimanbayev, Zhantore Dzhurkanov

"Recycling of industrial waste provided they have enough valuable elements requires significantly less investment compared with ore processing. Promising man-made raw material of rare earth elements (REE) is phosphogypsum. Works performed on dismantlement of phosphogypsum only concern phosphogypsum processing from apatit. In this case, none of the developments was tested for phosphogypsum produced on the basis of phosphorus, chemical and mineralogical composition of which is markedly different from apatites. We studied phosphorites of the Karatau deposits (Kazakhstan). Mineralogically all the layers are composed of three main ingredients: phosphate, silica and carbonate, which account for 92-96% of the weight composition of ores and rocks. Of impurities there are pyrite, iron hydroxides, gypsum, fluorite. In addition to the actual composition of phosphate in phosphate ores there are apatite. Silica is presented by chalcedony and quartz, and carbonate by calcite and dolomite. The results of X-ray microanalysis showed point cluster of grains containing REE in samples of phosphate ore. Analysis of the grain showed that REE are in the form of phosphates and silicates, which according to numerous studies in apatites is not established. In this regard, phosphogypsum, waste of production, is different in composition too. Therefore, transfer of techniques proposed in the methods for extracting REE from phosphogypsum after processing apatite, did not give the stated results and required a new approach to solving this problem. It should be noted that the phosphogypsum produced by processing the Karatau phosphorite contains medium group of REE by 2.6, and heavy group by 7.8 times more than phosphogypsum from processing the Kola apatite. Given the shortage of medium and heavy REE research to develop ways to extract the lanthanides from phosphogypsum after processing phosphate rock is promising. The study contains results of studies on the extraction of REE from phosphogypsum after Karatau phosphorite processing."

Jan 1, 2014

By V. Avdochin

The main reason of flotation process fluctuations is mixing ores of various properties from various sections of a deposit. Other, also important reasons are changes in parameters of facilities of technological cycle, as well as properties of reagents applied. According to estimates, instability and non-optimized parameters of flotation owe 3% to 6% of valuable component losses. Without ore averaging systems flotation process is characterized by considerable fluctuations of all input, output and intermediate parameters. Stab One more way is optimizing the process, providing for determination and maintaining optimal parameters of the process. In these conditions application of various mathematic models does not allow controlling the process by the way of action on input parameters of the process with further precise reaching required values of output parameters. More effective is to be application of flotation models for solution of questions of choosing and optimizing of automatic control systems. The work presented examples of application mathematic model of flotation process for estimation of effectiveness and choice of parameters of automatic control system that reduces considerably a stage of preliminary studies in elaboration, designing and modernizing automatic control systems.

Jan 1, 2014

By Bert Huls

Already starting, new drivers will dictate how future mineral processing plants will be designed and operated. These drivers include requirements in water and energy conservation because of rising costs, larger demand for mineral and metal products as the result of a rising population, and the increasing demand from the population in general to have influence over what type of operations will be developed where. Mineral operating facilities will require processing of lower grades. To do this economically, design engineers will be influenced to introduce newer concepts, or return to older processing concepts once deemed not desirable. Our understanding of the fundamentals must be improved, and this may come from better measurement techniques and more process piloting, and will go in hand with a reduction of waste generated during the process, improved separation of minerals or product size. Process engineers will also be required to not just design according to the established 3D methodology for efficient plant installation. Already in other industries the design concept encompasses the entire range from source to product. Not only that, the design will be affected by public influence that must be illustrated prior to project execution. On the one hand, the added dimension in design may slow a project; on the other hand it may result in a blessing, and in a higher responsibility for engineering.

Jan 1, 2014

By D. P. Hatfield, G. de Jager

"Recent developments in image analysis techniques and the power of computer hardware have spurred international interest in the potential uses of image analysis techniques in a range of industrial applications. One of these applications is the control of the complex flotation process. Despite years of work, the flotation process is still poorly understood. Current attempts to control flotation cells focus on consistently duplicating the control achieved by human operators.In human control of flotation two of the dominant visual cues are the froth flow speed and the froth stability. These two factors can be measured and inferred respectively from image analysis of video of the froth surface. Two important hydrodynamic variables for control of the flotation process are the air addition rate and the level of the froth pulp interface.The current work focuses on the relationship between froth flow speed and the rate of recovery of concentrate from a flotation cell. Results are presented that show a strong relationship between flow speed and concentrate yield. These results include tests where the conditions in the cell were not changed, as well as tests involving changes to the cell level and air addition rate. Preliminary results are presented which show a correlation between froth stability and froth percent solids.Future developments of the system will include comprehensive froth texture typing, colour space and stability analyses."

Jan 1, 2003

By W. Rubarth

The kaolin losses in hydrocyclone classification are determined by the fines, which are discharged together with the water to the underflow. This paper presents an improved technique of water injection to the conical part of the cyclone applied especially for small cyclones in kaolin preparation. In small hydrocyclones water, injection is a sensitive process. Therefore, the process was stabilized by controlled water injection dependent on the measurement of the underflow shape. Three applications of this innovation are presented. In the first case, the water injection is applied for the separation stage in dilute suspension where the final product is produced in the overflow of a 50mm hydrocyclone. The underflow contains sand and residual kaolin. For a higher kaolin recovery, the underflow is usually treated downstream in washing cyclones. The wash water injection results in a 45 ? 50% - reduction of the kaolin fraction <25µm in the underflow. Thus, water injection to the classifying cyclone leads to a separation comparable with a downstream washing stage. An additional hydrocyclone stage can be deleted. The second application refers to a classification in dense suspension. Here, the underflow of the last hydrocyclone stage was directed to a washing in a 50mm hydrocyclone. The additional injection of 3L/min water in to the conical part of the cyclone reduced the kaolin losses by half.The third application was executed in the washing stage equipped with 75mm hydrocyclones where the underflow is directed to flotation. Using the water injection the kaolin recovery in this stage was increased by approximately 20%. Keywords: hydrocyclone, classification, kaolin beneficiation, water injection, underflow washing

Sep 1, 2012

By S. M. Javad Koleini

The aim of this research is to extract zinc from complex lead and zinc ore containing carbo- silicate lead and zinc minerals using sulphuric acid. Samples, taken from Dareh Zanjireh mine located in central of Iran, were subjected to leaching tests after calcination process. Experiments were planed according to the Taguchi statistical method. The calcinated samples contain 13.98% zinc and the constituting minerals being dolomite and zincate. Various parameters such as speed of mixing, temperature, time, solid to liquid ratio and pH were studied. A solid to liquid ratio of 1:6 gr/mL at 60°C and 800 rpm speed of mixing for 30 minutes resulted in a product with 85.96% zinc recoveries.

Jan 1, 2014

By Ho-Seok Jeon

The separation in gravity concentrators is based on the density difference between valuable and gangue minerals. In addition to density, many auxiliary parameters like particle size, shape, feed rate, pulp density etc. plays an important role in the separation. The performance efficiency of gravity units is largely based on the interference of such auxiliary parameters during separation. Many gravity concentrators are used for the beneficiation of cassiterite ores and performance of which are varying with different feed material, particle size and required enrichment from the unit. Selection of gravity units is generally based on laboratory testing and data collected from the previous experience. In the present investigation cassiterite ore collected from Uljin deposit, South Korea has been subjected to various gravity units like jig, spiral, and Knelson concentrator with the intension to pre-concentrate the ore. Second stage concentration was carried out using shaking tables. The article mainly summarizes performance evaluation methods employed for gravity concentrators. Selection of gravity circuit for the beneficiation of cassiterite was made on the basis of the recovery-grade curve, and Tromp curve methods. Keywords: cassiterite, gravity concentration, recovery-grade curve, sink-float test, tromp curve

Sep 1, 2012

By G. Mucsi, F. Kristály, Á. Rácz, É. Gregus, K. Bohács

"Stirred media mills are widely used in the industry for fine grinding. Most of the applications work in wet mode, however dry grinding in stirred media mill comes forward more frequently nowadays. The present paper deals with the differences and similarities of the wet and dry grinding in stirred media mill from energetic and mechanochemical point of view as well. Grinding experiments in batch stirred media mill were carried out with different materials. During the experiments zeolite and kaolin were used as feed material. The grinding experiments were carried out at different stress energy and stress number values; the grinding work was measured during milling. After grinding X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), particles size analyzes by laser scattering were carried out on the ground materials. As a result of the systematic grinding and analytical measurements a comprehensive comparison was carried out on the wet and dry grinding and their usefulness for mechanical activation in stirred media mill. INTRODUCTION The natural zeolites are crystalline hydrated aluminosilicates of alkali and alkaline earth characterized by the structure that contains frameworks responsible for the high cation exchange capacity (CEC) and absorption capacity. The frameworks are interconnected by cavities and resided by cations variable in size, coordinated by water molecules. Since zeolite comprises SiO4 and AlO4 tetrahedra interlocked by oxygen atoms that are situated in the structural nodes, their characteristics differ due to the varieties in the structure-directing agents and Si/Al ratio (Colella and Wise, 2014; Malekian et al., 2011; Terzic et al., 2017). The most common natural zeolite occurring in high amount, of industrial importance and involved in milling and MA is the clinoptilolite, in the literature equivalent to “natural zeolite” designated for high clinoptilolite bearing volcanic tuffs. Its amount in the host rock must reach ~ 40 % by weight to obtain the CEC and adsorption desired in its applications. In the highest quality rock might reach 80-90 % by weight (Favvas et al., 2016), but most often is the 40-60 % by weight content, associated with smectites, improving the CEC and adsorption of the tuffaceous rock. The application of such natural zeolites is problematic in many cases due to high silica (quartz, cristobalite and volcanic glass) content and beneficiation (concentration and extraction of pure zeolite) are not feasible. Thus, mechanical activation is a possible way to alter the other than clinoptilolite minerals generating high specific surface area and functionalized particle surfaces to enhance adsorption, reaction or particle adhesion. The zeolites easy availability and the utilization cost-effectiveness have prompted the research on their physicochemical and structural properties (e.g. adsorptive and molecular-sieve activity, heat resistance, and microporous cage structure) and finding new options for their application (Kusuma et al., 2013; Musyoka et al., 2014; Rida et al., 2013; Terzic et al., 2015b). Apart from the presence of exchangeable framework cations which are crucial for the adsorption ability, and a certain degree of pozzolanic reactivity. The thermal stability of dehydrated phases is another important characteristic for use of the zeolite in composite materials that are exposed to high temperature. Thereby, the zeolites found a wide application possibility in the design of the construction composites (Albayrak et al., 2007; Najimi et al., 2012; Vejmelková et al., 2015), as well as for resolving of the environmental protection issues like wastewater refining or heavy metal elimination (Gómez-Hortigüela et al., 2014) even from contaminated groundwater using passive methods like permeable reactive barriers (Gombköto et al, 2016). The grinding treatment of zeolite is a common and frequently applied procedure, both on laboratory (Bohács et al. 2017, Faitli and Czél, 2014)"

Jan 1, 2018

By S. Banisi, E. Arghavani, M. Pourkani, M. J. Rajabi, Gh. A. Mohamadian, H. Bidshahri, Gh. A. Parsapour

The Sarcheshmeh copper complex flotation circuit of plant No.1 consists of two identical north and south sections where each includes four rougher (each bank consists of 14 cells), two cleaners (each bank consists of 8 cells), two recleaners (each bank consists of 2 cells), and two scavenger banks (each bank consists of 10 cells). The reduction of feed grade along with a change in the mineralogical composition is the main reason of current lower concentrate grade (24%) compared with the design concentrate grade (32%). Because of a lower feed grade, the amount of rougher concentrate has decreased which in turn has significantly reduced the feed rate to the cleaner, recleaner, and scavenger banks. This has increased the mean residence time of the material in the cleaner section resulting in a lower final concentrate grade. A laboratory study showed that the final concentrate grade can be increased by 2-4% if one cleaner stage is added to the flotation circuit. In this research, based on the laboratory results, one cleaning stage was added to the current flotation circuit. In order to make this modification instrumentally possible in the plant, the final concentrate was gravity transported to the Mo-Cu thickeners. This released 2 pumps and associated tanks which made addition of one cleaning stage practicable. Finally, a part of the cleaner and scavenger cells were used as the third cleaning stage. This decreased the residence time in the cleaner and scavenger banks. After implementation of one cleaning stage in the south section of the plant, the performance of the circuit compared with the identical north section. It was found that at the same recovery, the concentrate grade of the south section increased by 2.5%. The promising results led to the implementation of adding one cleaning stage in all sections of the flotation circuit.

Jan 1, 2018

By Sergey Romanenko, Tatyana Aleksandrova, Karen Arustamian

"Current status of question about grinding stage effect to electrochemistry parameters of operation preparation slurry before intermediate selective flotation was assessed in the present scientific work. Needs of more detail study chemical reactions in the slurry preparation and flotation processes were shown. The ores are polymetallic sulphide type and the one are most difficult for mineral processing. The methodology allows increase information base during floatation tests. Ionometric methods and elements of neural network have been used in the study of mineral processing questions.We have also identified the relationship between the received values of the electrochemical parameters and the technological results in selective flotation. The optimal values of the electrochemistry parameters in operation of the preparation slurry before selective flotation has been found. The main effect of using the proposed methodology is to obtain scientifically based solutions to improve the technology parameters of flotation polymetallic sulfide ores. Challenging issue of selectivity of sulphide-polymetallic ores will be considered using case study of sulphidepolymetallic ores. It was shown that several factors are formed in ore grinding: formation of hydroxyl oxides of iron compounds, copper cation leaching, metal-sulphide and metal-sulphite complexes formation. The chemistry was revealed for current processes in slurry preparation operation before selective flotation. Quantitative assessment of interrelations between electrochemical parameters of slurry and process performance was given with using electrochemical control methods. Neuron network-based model was estimated based on data array and was allowed to establish optimum electrochemical conditions of metal-sulphite complex formation to provide maximum efficiency of selective flotation.INTRODUCTIONPhysical and chemical processes that take place in ore grinding have a significant impact on flotation selectivity and can cause low selectivity of the flotation process. Today this issue is given much attention. In the paper [1] it is pointed out that sulphide oxidation products and slurry components, such as sulphide ions, metallic iron and its oxidation products, have effect on flotation performance. So, metallic iron has impact on metal-sulphite complex formation as a result of oxidation-reduction reactions as follows:"

Jan 1, 2018

By V. A. Feofanov

Technogenic water of ore mining enterprises, nonferrous metals operations, the enterprises of electroplating and instrument making, containing copper in the form of those or other connections can serve as perspective sources on receiving the copper-bearing raw material. Extraction of copper from the given water also solves a problem of water treating from a toxic component that reduces environmental load at evacuation of water in an open basin. The method of case hardening allows extracting copper selectively with reception of a deposit with the content of copper up to 70%. Weakness of the method is its efficiency basically in acid reduction, and also its low degree of copper extraction. On the basis of case hardening the method of galvanic coagulation is devised. It is based on the work of a short-circuited galvanic cell of iron-coke at variable contact of coupled metals components among themselves, cleared by the oxygen of air. The following processes of galvanic coagulation are considered: ? Extraction of copper; ? Formation ferrites of copper; ? Copper sorption on just-aggregated oxide forms of iron. Establishing conditions for passing the given stages provides an opportunity of copper extraction from technogenic water at any value of ??, content of salt and concentration of copper with reception of a compact deposit from which it is possible to extract copper by the known ways of enrichment and metallurgy. Investigations on optimization and intensification of galvanic coagulation with the purpose of reception the maximum rich deposit on copper have shown that the average contents of copper in a solution of 100~200 mg/dm3 the contents of copper in a deposit is 6%~10% at extraction 85%~90%, depending on characteristics of treated technogenic water. Using methods of scanning microscopy it is determined structures, composition and mechanism of phase formation in investigated electro-chemical process. The second stage of galvanic coagulation increases a degree of copper extraction up to 98%~99% that allows returning the cleared waters in circulation for waste recycling or evacuation in an open basin. Nowadays the method of galvanic coagulation is the most acceptable for copper extraction from technogenic water both from the point of view of efficiency and instrument setting that allows applying the method in conditions of the working enterprises.

Jan 1, 2014

By I. Yu. Rasskazov, A. V. Rasskazova, N. M. Litvinova, N. A. Lavrik, V. G. Kryukov

The possibility of the intensification of the gravity processing of complex iron-manganese ore, which contains the finely dispersed inclusions of gold and platinum is shown. Clear mineral fractions of precious metals were sorted out of the different types of ores (quartz-braunite and carbonate- magnetite ore, ferruginous quartzite, carbon-containing shale, breccia-limestone and dolomite breccia). Composition and structures of precious-metals particles was detailed. The industrial content of platinum and gold was found. Precious-metals mineralization is character for all types of ores. High content of platinum is indicated in the carbonate-magnetite (up to 11.3 mg/kg) and quartz –braunite (up to 10 mg/kg) types of ore. Gold is presented in the ferruginous quartzite (up to 1.29 mg/kg) according to the data of the reduced mineralogical analysis. The composition of native platinum depends on the type of the ores: 1) quartz-braunite type contains isoferroplatinum (Pt3Fe) with Cu, Rh, Ir, Ru; 2) carbonate-magnetite type contains isoferroplatinum with Cu, Sn, Ni, Rh, Ir, Os; 3) pyritic-carbon ore contains isoferroplatinum with Sn, Ni; 4) ferruginous quartzite contains isoferroplatinum without admixtures. The ultrasonic treatment of mineral aggregates (P = 41.5 Watt, I = 15 W/cm2) made possible the liberation of fine particles of precious metals. Smooth-shaped or crystalline mineral aggregates are effectively liberated after acoustic treatment. Their surface is freed from impurities. The aggregates with the complex form and structure, which consist of the numerous plates and the grains, are not effectively liberated from impurities. It is shown that the ultrasonic treatment of aggregates with the fine inclusions of precious metals contributes to the liberation of the particles of platinum and gold and intensification of the gravity processing of refractory ore. This approach contributes the increase of the raw-material base of precious metals.

Jan 1, 2018

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

Jan 1, 2014

By Klaus M. Hahn, Kurt Aasly, Jutta Lennartz, Hermann Wotruba, Ben Snook, Przemyslaw B. Kowalczuk, Rolf Arne Kleiv

"Seafloor massive sulphide (SMS) deposits have been identified as important marine metal resources for the future. However, literature on mineral processing of SMS is currently limited, and to date, no research has been published on processing of SMS from either active or inactive hydrothermal vent fields on the Arctic Mid-Ocean Ridge. In this paper, individual SMS rock samples from the Loki’s Castle area were tested. Chalcopyrite, isocubanite and sphalerite represented the main copper and zinc bearing minerals in the SMS samples, whereas the gangue consisted of barite and silica. Based on the X-ray transmission response (XRT), i.e. differences in the atomic number of elements in tested samples, and using portable XRF (PXRF) values of elemental composition, individual particles were classified as a either product (low barium / high to low silicon / high copper and zinc) or waste (high barium / high silicon / low copper and zinc). The classification was based on the elemental composition of the samples with the cut-off grade equal to 0.5% for copper. It was shown that the XRT discrimination analysis correlated well with elemental (PXRF) data classification. The results clearly indicate that X-ray transmission sensor-based sorting can be used a useful technique for preconcentration of SMS rock samples. INTRODUCTION Due to different compositions of investigated samples, sensor-based sorting is a useful technique for preconcentration of different materials. The aim of using sensor-based sorting is to upgrade an ore by reducing the quantity of overall waste material reporting to the next processing stage. This can be achieved by eliminating (reducing) the waste fraction. By applying sensor-based sorting, the energy consumption for particle comminution as well as the required process water and reagents can be decreased. The total volume of the waste rejection leads to a proportional reduction in the total energy costs (Lessard et al., 2014, 2016)."

Jan 1, 2018

By V. E. Vigdergauz

The work presented shows results of electrochemical study of pyrite hydrophobicity evaluated by air bubble induction time (IT) measurements. On the basis of measured IT?s an average thickness of the thin liquid film prior to its rupture has been evaluated, which confirms long-range character of the interactions between air bubbles and hydrophobic surfaces. Obtained data are discussed in the frame of recent studies of structures of solid-liquid interface based on molecular dynamics simulations and results of surface force measurements.

Jan 1, 2014

By M. Paymardi, A. Foroutan, T. P. Oladele, M. Abbaszadeh

"Reducing the amount of zinc and iron in lead concentrate is one of the important aspects of processing in lead and zinc flotation plants which results in improvement of lead concentrate quality and prevents zinc loss. In mineral flotation industries, lignin sulfonates are known for their depressant properties for both non-metallic and sulfide minerals such as pyrite and pyrrhotite.This paper investigates the effect of lignin sulfonate on flotation of galena, sphalerite and pyrite in sulfidic lead and zinc bearing ores. Batch flotation tests were carried out on a high pre-activated zinc samples. The feed contains 0.9% lead, 2.3% zinc and 7.5% iron. The dosage of all reagents such as sodium cyanide, zinc sulfate, ethyl xanthate and methyl isobutyl carbinol (MIBC) were kept constant for lead flotation step except calcium lignin sulfonate (CLS) that was varied between 0 and 80 gr/ton.Results for lead rougher concentrate showed that the grade of lead increased by 2.7% while the recovery decreased around 4 % at the highest dosage of CLS. Furthermore, zinc recovery decreased by 6.3% with no significant change in grade. Iron recovery in lead rougher concentrate decreased by 2.3 % while the grade changed around 1%. In sphalerite flotation step, CLS dosage was changed in the range of 0 to 80 gr/ton while the dosage of other reagents such as copper sulfate, lime, amil xanthate and MIBC were kept constant. In this step, no decreasing in grade and recovery of zinc was observed, while iron recovery decreased. It was suggested that CLS has a depression effect on sphalerite in conjunction with other zinc depressants such as zinc sulfate and sodium cyanide. CLS was further used in plant with non-pre-activated zinc minerals. Similar trends were observed in plant.INTRODUCTIONlead-zinc sulfide minerals play an important role in the production of lead and zinc metals in the mineral processing industry (Luo, Feng et al. 2016). Due to complexity of the lead-zinc ores mineralogy, in some situations, their flotation properties vary significantly from one deposit to another one even in itself (Bulatovic 2007)."

Jan 1, 2018

By A. Üçyildiz

Magnesium borates of varying compositions and properties are synthesized using different reagents and methods for the possible potential uses as termoluminescent material, anti-wear and anti-friction additive, fire retardant, catalyst for the conversion of hydrocarbons, whisker material and ferroelastic material. In the current work, the conditions for synthesizing MgB4O7 compound by high-temperature solid-state reactions were investigated using boric acid and magnesium oxide as the starting materials. The MgO:B2O3 mole ratios applied in the experiments were 1:1, 1:2, 1:3 and the thermal behaviours of each mixture were studied between 25~1200°C by TG/DTA analyses under static air atmosphere to find out the probable formation temperature of MgB4O7 phase. Considering TG/DTA results, freshly prepared boric acid and magnesium oxide solid mixtures were heated at predeter-mined temperatures and the phases were identified by XRD analyses. Accordingly, MgO:B2O3 mole ratio of 1:2, heating temperature of 950°C and a reaction time of 2 hours were selected as the optimum conditions for the formation of maximum amounts of MgB4O7. After obtaining solids prepared at the pre-determined optimum conditions, their chemical composition, IR spectrum, TG/DTA pattern, B.E.T. surface area value, particle size distribution and SEM images were deter-mined to point out the possible use areas. Experimental results showed that it was not possible to obtain pure product at the optimum conditions due to formation of minor amounts of t-Mg2B2O5 and the presence of some unreacted B2O3. The product synthesized has the potential for use as a corrosion inhibitor on some metal surfaces.

Jan 1, 2014

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