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By V. Vogt

During the phosphating of car bodies containing aluminium, the employed phosphating chemicals zinc, manganese and nickel are, for thermodynamic reasons, only used to a limited extent for the desired surface coating. The major proportion of these metals is discharged together with the incidental cryolite-containing phosphating sludges and the rinse water. Commissioned by the German Federal Ministry of Education and Research (BMBF), the Institute of Mineral and Waste Processing, Waste Disposal and Geomechanics at the Clausthal University of Technology has developed a two-stage process for the production-integrated recovery of the dragged out chemicals and for closing the rinse water cycle for Audi AG. During the first stage, the phosphating chemicals are recovered by means of leaching. In the second stage, the rinse water is treated by means of electroflotation followed by an ion exchanger.

Jan 1, 2014

By V. E. Dementyev

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

Jan 1, 2014

Optimising flotation designs and innovations is a complex process involving many parameters, one of which is ensuring sufficient testwork is carried out at plant level before these innovations are launched in the marketplace. This paper will describe how modern design tools are utilized, what are testwork phases at various plants and how results and observations have helped to validate and optimise flotation design innovations. Scale-up of equipment has long been the prevalent trend, but how long can it continue? Are there other means for pushing the boundaries of present technology? Some present challenges and future directions are given in the light of theoretical criteria for scale-up and how it has been applied in practice. Very large flotation cells of 300 m3 size have been installed in New Zealand, and relevant results from the metallurgical and mechanical aspects are presented and discussed. Utilization of the cell volume is also important. New innovations in the hydrodynamic domain are presented and discussed. Means to enhance flotation of coarse and fine particles are shown with results from plant testwork. Accurate control of large flotation cells is vital to optimize yields and grades. Froth image analysis and intelligent level control are presented ? again - with relevant plant results.

Jan 1, 2014

By Auhin Kumar Maparu

Metal oxide nano-particles are used as additives in various industrial applications such as pigments in paints, additives in adhesives, plastics, cosmetics, functional coatings, personal care and health care products, for antibacterial applications and more recently in heat transfer applications. In most of these applications, usually dry nano-particle powders are added to the formulations. However, often it becomes difficult to achieve a uniform and stable dispersion of nano-particles in the given formulation. Thus, a scalable and commercially viable process for in-situ production of stable nano-particles suspensions in the desired medium will certainly be more beneficial. Ultra-fine grinding in high energy mills (planetary mill, stirred media mill) has been used to produce fine particles (sub-micron size). However, in order to obtain nano-particles (particle size <100 nm), the choice of appropriate dispersant and solvent is crucial, since freshly generated nano-particles tend to agglomerate due to their high surface reactivity. We have employed molecular modeling (MM) based selection methodology to arrive at the most suitable solvent?dispersant combination for preparation of the given metal oxide nano-particles. Molecular modeling techniques are employed to compute the interaction energy of a given dispersant with surface of the metal oxide particles in the presence of the dispersion medium. The interaction energy helps identify a dispersant that has strong affinity for the metal oxide surfaces allowing for strong dispersant adsorption and hence a more stable dispersion. For example, in case of aqueous nano-titania suspensions, poly-carboxylic acids like citric acid provide better dispersion than mono-carboxylic acids like lauric acid, mysristic acid, and oleic acid. While in non-aqueous medium like ethanol, p-hydroxybenzoic acid and glycerol trioleate perform better. The suspension is produced in-situ by ultra-fine grinding of the metal oxide powder in the presence of the selected dispersant and dispersion medium in a planetary ball mill. By careful selection of various process parameters such as percent loading of powder, jar filling, grinding media to powder ratio, time and amount of dispersant addition, both aqueous and non-aqueous suspensions of metal oxide nano-particles with average particle size less than 100 nm are produced. The aqueous suspensions of alumina and titania produced in presence of citric acid dispersant exhibit median particle size of 83 and 62 nm, respectively. These suspensions have been found to be stable for nearly 3 years. The nano-particles thus produced are used in the preparation of nano-fluids?advance heat transfer liquids, which show enhanced heat transfer capabilities and unaltered stability and performance even after several heating-cooling cycles. The nano-particles are also utilized for making efficient photo catalysts, which are found to be highly effective under sunlight. Keywords: stability, nano-fluid, milling, grinding, thermal conductivity, nanocoolant, photocatalyst

Sep 1, 2012

By Ingvar Ymén, Anders Sandc, Jan Rosenkranzc, Lisa Malma, Ann-Sofi Kindstedt Danielssonb

The understanding of particle surface properties is essential for the study and evaluation of froth flotation phenomena, particularly in the investigation of various chemical or reagent effects. Dynamic Vapor Sorption (DVS) is a method used for the analysis of surface properties of powders for instance in the pharmaceutical industry. To the knowledge of the authors, it has however not been used before in applications related to mineral processing. The DVS technique involves measurement of the water uptake of a relatively small amount of sample as a function of the relative humidity (% RH) in a temperature-controlled environment. The purpose of this work was to evaluate the method and investigate how it can complement existing techniques for surface characterization in mineral processing. Four samples (feed, CuPb concentrate, Cu concentrate and Pb concentrate) from the Cu – Pb flotation process in the Garpenberg concentrator, Sweden, were analyzed by DVS and the traditional capillary absorption technique (Washburn capillary rise). This enabled comparison between the two methods and evaluation of their respective advantages and disadvantages. Both methods give the expected ranking of the hydrophobicity for CuPb concentrate, Cu concentrate and Pb concentrate, but a discrepancy was observed for the feed. Washburn gave a value for the contact angle which was in the same range as for the CuPb concentrate, whereas DVS gave a value for the moisture uptake which was much higher than for the CuPb concentrate. Thus, DVS ranks all samples correctly, but with an unexpectedly high value for the feed whereas Washburn gives good ranking for three samples out of four. Potential reasons for the discrepancies are discussed.

Jan 1, 2018

By A. K. Suri

India plans to increase the nuclear power share in overall energy-mix to about 30% by 2032 using both indigenous and imported reactor technologies. In the immediate time-frame, it is envisaged to generate 10000 MW electricity by PHWR technology by 2020 using indigenous uranium resources. This necessitates setting-up of new uranium mills and augmenting the existing resource, mining and milling capacities. This paper describes the current status and future R & D needs towards achieving the targeted demand of yellow-cake. Keywords: uranium, hydrometallurgy, leaching, yellow cake

Sep 1, 2012

By Cheng Wei

Fly-ash was used as adsorbent to remove butyl xanthate from aqueous solution in this study. Adsorption kinetics investigation reveals that the adsorption process abides by the Lagergren-second-order Kinetic Model, and fine fly-ash prepared by grinding has a higher second-order adsorption rate as 1.25 g/mg?min and a higher saturated adsorption amount as 10.92mg/g. Four influencing factors as adsorption temperature, solution pH, consumption of fly-ash and adsorption time were investigated. Testing results indicate that butyl xanthate removal rates declines slightly with the temperature increase within the range of 15-50?, increases slightly when pH rises from 7.27 to 8.01 and then declines from 99.65% to 98.25% when pH rises from 8.01 to 11.10. An enhancement of removal rates can be observed by increasing the consumption of the adsorbing agent or prolonging the adsorption time. Thermal desorption was adopted to regenerate the used fly-ash, and test results show that fly-ash possess good regeneration performance and could be used as adsorbent repeatedly with little influence on the adsorption capacity.

Sep 1, 2012

By Gu Guohua

The alteration of surface properties of chalcopyrite after biological conditioning with Leptospirillum ferriphilum was studied by adsorption, zeta-potential, contact angle and bioleaching tests. The strains of L. ferriphilum cultured using different energy sources (either soluble ferrous ion or chalcopyrite) were used. The adhesion of bacteria to the chalcopyrite surface was a fast process. Additionally, the adsorption of substrate-grown bacteria was greater and faster than that of liquid-grown ones. The isoelectric point (IEP) of chalcopyrite moved toward that of pure L. ferriphilum after conditioning with bacteria. The chalcopyrite contact angle curves motioned diversely in the 9K culture with and without chalcopyrite powders. The results of X-ray diffraction patterns (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis indicated that in the bioleaching process by L. ferriphilum, the surface of chalcopyrite was covered with sulfur and jarosite. Furthermore, iron phase dissolved preferentially from chalcopyrite surface during bioleaching from EDS detection. The copper extraction was low resulting from the formation of a passivation layer. The major component of the passivation layer that blocked continuous copper extraction was sulfur, not jarosite.

Sep 1, 2012

By S. Safak

Europe retains a modest position in world mining activity in terms of scale of production and mineral reserves but maintains a non-negligible role in the world mining industry. The concept of sustainable development resting on three pillars of economics, environment and social development has become an increasingly important factor in the European mining sector and a major influence on the related policies of the European Commission. Members of European mining industry shall conduct their activities according to the principles which promote sustainable development. A successful minerals planning policy should create the legal administrative environment that is necessary to ensure the sustainable supply of minerals to society within the framework of sustainable development. Members of the European mining industry shall conduct their activities according to principles which promote sustainable development. The challenge for sustainability is to find a balance between securing minerals supply, protecting the environment and achieving social progress. The point of balance depends on the range of policies adopted by governments. In this paper the development of the sustainability of the mining sector in EU and the social component of sustainability in the mineral industry is discussed.

Jan 1, 2014

By S. Chuanyao

In last decade, along with its booming Chinese economy, China?s higher education has experienced rapid growth. In 2010, the number of various colleges totals more than 3500, with 2.2 million faculties registered. Currently there are almost 30 million students studying in the colleges, 3 times more than 10 years ago. Mineral Processing was initiated in 1949 as a sub-discipline of Mining Engineering, one of the 13 first level disciplines. Mineral Processing is now established in 34 Chinese colleges, recruiting 2600 undergraduate students, 540 postgraduate students and 100 PhD students every year. A further 9 institutes offer postgraduate education in this field. More than 3000 graduates majoring in Mineral Processing join the industry or institutions each year. The four-year undergraduate teaching and practical training in the colleges is designed to produce qualified mineral processing professionals. This includes courses in mathematics and natural science, fundamental engineering and basic and specialization courses. Recently, the ?Excellent Engineer Program? was launched to strengthen students? practical capabilities. This is a 3+1 teaching and training model; 3 years of theoretical course study plus 1 accumulated year of various practical studies, either inside or outside the college. As for graduate employment, mining-related major graduates have been in a good demand thanks to the intensive investment in mineral sector by Chinese companies. The shortage of experienced metallurgists generates a greater than 90% employment rate for Mineral Processing graduates. However, the biggest problem we are still facing is the gap between the quality of the graduates and the requirements of industry, as a result of occupation attraction, teaching systems, faculty quality, and so forth. Another problem is international orientation. Although nowadays Chinese-foreign cooperation in college education is popular, collaborative mineral related projects are far less common, leaving much room for improvement. Looking ahead to the next 10 years, we still have the right reasons to estimate continued prosperity in the minerals sector as well as mineral processing education in China. A brief analysis and views on this will also be shared in the presentation. Keywords: China, mining engineering curriculum, excellent engineer program

Sep 1, 2012

By Z. L. Huang

A new porous apatite product was prepared using phosphorite from Yichang China by a tem-plate-directed method in self-made reaction equipment under constant temperature and pressure. The product was characterized by XRD, FT-IR and SEM. The results showed that the product was a kind of micrometer porous sphere three-dimensionally structured by apatite nanoflakes, that the average thickness of nanoflakes was about 50 nm, that the average pore size was about 1.2 µm and that the particle average size was about 20 µm. Great amounts of Ca2+channel, high special surface area and regular spherical shape show the potential promising applications of this special porous apatite product in the fields of catalyst, medication, chemical engineering and environment engineering

Jan 1, 2014

By A. L. Hinde

The steady-state and dynamic behaviour of semi-autogenous grinding (SAG) mills are arguably best described using a population model that caters for the breakage kinetics and the material trans-port of rock and pulp inside the mill. Breakage kinetics are usually expressed in terms of a specific breakage rate function and a separate primary breakage distribution function. Material transport usually invokes the concept of a specific discharge rate function. Unfortunately, the breakage rate and breakage distribution functions for SAG mills are very difficult to estimate uniquely from plant data alone. Simplifying assumptions must be made to over-come this problem, which leads to many unresolved dilemmas with regard to whether or not the de-rived functions are accurate, precise, and reflect reality. For example, it is sometimes assumed that the breakage distribution function for a SAG mill treating run-of-mine ore can be derived from laboratory dropweight and tumbling tests on small rocks in narrow size ranges. Such tests hardly reflect the environmental conditions likely to be encountered in a pilot or production SAG mill where there is a wide spectrum of particle sizes. It is shown that the dilemmas associated with standard population balance models (models that utilise separate breakage rate and breakage distribution functions) can be overcome by expressing breakage behaviour inside a SAG mill in terms of a single function. This function is an energy-based cumulative breakage rate function defined as the fractional rate at which particles and rocks coarser than a given size break to below that size per unit specific energy input. A model for SAG milling is formulated, which invokes the concept of a cumulative breakage rate function. Comparisons are made between the mathematical structure of this ?simple model? and standard population balance models. Perhaps the most attractive feature of the ?simple model? is that the cumulative breakage rate function can be uniquely estimated from measurements of size distributions and mass flows of the feed and discharge streams together with the size distribution and holdup mass of the mill charge. Such measurement can easily be made at pilot scale. It is concluded that this simplified approach to SAG milling may turn out to be the quickest way to fully describe and quantify the performance of these very complex mills.

Jan 1, 2014

By X. Cui

Hydrocyclone is widely used in closed-circuit grinding process. However, in the first classification operation of coarse particles with high pulp density, the shortcomings of traditional cyclone are that the grinding cycle load is much high, the apex of cyclone is easily to be blocked and classification efficiency is less. Specifically, the problems of traditional cyclone used in grinding process are as follows: (1) Mill utilization factor is low and its handling capacity is small. (2) Coarse particles mixing in cyclone overflow affects the following separation process and fine particles mixing in underflow causes over-grinding, which affects the total recovery rate of valuable minerals. (3) High grinding cycle load leads to large amount of high-density slurry pumping, which causes high energy consumption and severe wear of cyclones, pipelines and pumps. The applications of new type pre-classification hydrocyclone with centrifugal volute in the first classification process of Iron Mine Mill are introduced in the paper. Pulp particles fed in the centrifugal volute were arranged in advance, so that coarse particles can be far away from the overflow pipe, which can reduce the short circuit current to avoid coarse particles entering overflow and improve classification efficiency and accuracy of cyclone. The strong points of the new cyclone in the coarse classification operation are as follows: (1) finer overflow and less fine particles mixing in underflow improves classification efficiency more than 10%; (2) lower ball mill load cycle improves ball capacity more than 10%;(3) grinding energy consumption reduces by more than 20% and cyclone feed pump reduces energy consumption by more than 12%. In short, new type pre-classification cyclone with centrifugal volute solves the problems of fine particles mixing in underflow, high grinding cycle load and less classification efficiency in the coarse classification operation. Therefore, it has broad application prospects in ferrous metal and non-ferrous metal ore dressing plant.

Sep 1, 2012

By A. A. Sirkeci

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

Jan 1, 2014

By C. L. Tang

Parts of the wastewater are reused directly and the rest moderately purified and reused, so the utilization rate of wastewater of the whole processing plant reaches 100 percent. At the same time, beneficiation indicators have been improved stably, and great economic and social benefits have been achieved.

Jan 1, 2014

By A. M. Ozbayoglu

Gross calorific value (GCV) of coals was estimated using artificial neural networks, linear and non-linear regression techniques. Proximate and ultimate analysis results were collected for 187 different coal samples. Different input data sets were compared, such as both proximate and ultimate analysis data, and only proximate analysis data and only ultimate analysis data. It was observed that the best results were obtained when both proximate analysis and ultimate analysis results were used for estimating the gross calorific value. When the performance of artificial neural networks and regression analysis techniques were compared, it was observed that both artificial neural networks and regression techniques were promisingly accurate in estimating gross calorific values. In general, most of the models estimated the gross calorific value within ±3% of the expected value.

Sep 1, 2012

By T. Damyanov

Spherical grinding media (balls) are the most widely used media for comminution of ores by grinding. A modelling simulation study of the behavior of two grinding media in the grinding process was conducted to determine the possible advantages of the new shape milling bodies called tetraballpebs. Tetraballpebs are in the shape of tetrahedrons with spherical convex walls. A three dimensional CAD model of the mill drum with a diameter of 1200 mm was used. A continuous operating mode was simulated in terms of the 3D contact elements of the model (milling bodies and mill drum). Simulation tests were carried out in a typical grinding mode and at a typical rotational speed of the drum mill (75 per cent of the critical speed in cataracting mode). Studies carried out with both grinding media include equal number of milling bodies with the same weight and volume. Having thus ensured a uniform mass of the grinding media and same number of milling bodies, and constant other conditions and process parameters, conclusions can be drawn about the influence of the shape of the milling bodies on the grinding process. A kinematic analysis of the system using CAE (computer-aided engineering) model parameterization was conducted. The controlled parameters are: ? Power draw; ? Kinetic energy of each milling body; ? Motion of milling bodies inside the drum Keywords: grinding, grinding simulation, balls, tetraballpebs, DEM, CAD-CAE

Sep 1, 2012

By Shi Shuaixing Zhang Yuejun, Fan Xuesai Zhangming

"For the traditional principle of flotation cell design, or in the perspective of some researchers, the mixing effect of impeller for flotation cell is not only to suspend the particles off the bottom, but also to mix slurry well to achieve a uniform system. But for some special processing conditions, the depth profile of slurry concentration and particle size demonstrates an obvious difference. In the part around of the impeller in the cell, the slurry concentration is much higher than the part below the lip.For the vanadium titano-magnetite flotation process, distinguished with high concentration and large coarse particle size fraction, even though the concentration is very high, it can reach good gas dispersion, which is a fundamental principle for flotation cell design and application. The gas dispersion is not a challenge in the high slurry concentration environment, not only in the vertical direction, but in the cross section. Different levels (the distance from the lip is 400mm, 700mm, 1200mm, 1700mm, 2200mm, 2700mm) slurry in the flotation cell is sampled and analyzed. The slurry concentration of the 3 levels(1700mm, 2200mm, 2700mm) is about 55%, but the slurry concentration decreases from 55% to 25% sharply towards the lip.Therefore, a new understanding and viewpoint is presented, that the uniform system of slurry is not always reasonable for all of the flotation process. For some special process, if the coarse particles are needed to agitated well and transported to the upper cell, the quiescent zone in the upper cell will be destroyed and enhance the detachment probability for the coarse particles. The difference of slurry concentration and particle size fraction benefits the air dispersion and coarse mineral particles recovery.1.INTRODUCTIONNowadays, flotation is the most widely used separation process in the mineral processing industry. The importance of flotation technology in the global economy is significant. A rough estimate of the quantity of crushed ore treated by flotation is about nine billion tons per year, and the portion of base metals processed using this method is approximately 95% (Brewis, 1996)."

Jan 1, 2018

By Hui Zhang, Fei Yang, Tong Guan, Guangqin Fu, Lihong Deng, Yuanlin Chen, Xiaotong Zhou

"For a copper-sulfur polymetallic mine in south China, the main valuable minerals were chalcopyrite, pyrite and pyrrhotite. The flotability of pyrrhotite was similar with chalcopyrite and pyrite and it was easy to be oxidized. As a result, the indexes of copper concentrate and sulfur concentrate were unsatisfactory. Furthermore, the recycling of tailings water ulteriorly deteriorated the technical indexes of copper-sulfur ore beneficiation. After a large amount of experimental studies, under the condition that the tailings water recycling rate was 100%, the copper concentrate with a grade of 22.25%Cu and a recovery of 82.46% on average was obtained for the raw ore containing 0.517%Cu, 15.94%S, 25.46%Fe on average, through using new technology “magnetic separation-flotation” and effective adjustment of parameters in the industrial test which was continuously conducted for 14 shifts in 5 days with a scale of about 75t/d. Comparing with the production indexes (the copper concentrate with a grade of 17.49%Cu, the recovery was 62.27%) during the corresponding period, the grade of copper concentrate increased 4.76%Cu, and the recovery increased 20 percentage points. Besides, the indexes of sulfur concentrate gained a considerable improvement. Currently, the new technology was adopted in the design of the new-built plant with a scale of 7000t/d of this mine. The new technology provided powerful support for the tailings water recycling and indexes improvement of copper-sulfur ore beneficiation.INTRODUCTION Chalcopyrite was usually associated with pyrite and pyrrhotite in copper-sulfur ore. Due to the similar flotability, it was difficult to obtain copper concentrate and sulfur concentrate with high grade. Furthermore, sulfide ore was easy to be oxidized and a large amount of ions formed in the pulp by the dissolution of minerals, which made the pulp become acidic. As a result, pyrite and pyrrhotite were easy to be activated in acidic solution and their flotabilities became stronger. Meanwhile, hydrophilic film formed on the surface of chalcopyrite in raw ore. The flotability of chalcopyrite became weaker and it made the separation of chalcopyrite from pyrite and pyrrhotite more difficult. So it was more difficult for copper and sulfur recovering with the recycling of tailings water containing high content of heavy metal ions and reagents."

Jan 1, 2018

By M. Kadiyski, V. Stoyanova, E. Visariev, V. Stoilov

"The present study deals with copper losses in slag from copper smelting. Copper slag cooling at Aurubis Bulgaria is traditionally done in pits. A new type of slag-cooling is introduced in the site, involving cooling ladles. In a previous study, the ladle cooling process was studied in detail, showing an improvement in the recovery of copper in the slag after flotation. The main reason for better recovery of copper is the increased cooling time, which allows for the accumulation and aggregation of copper droplets. The effects of the newly introduced slag cooling process are studied using optical microscopy and scanning electron microscopy. Cooling in pits and in ladles is compared, based on copper droplet size, distribution and content. Specialized image processing software is employed on images taken with an optical microscope. The results are then compared with a similar technique, available in SEM software. The availability of phase-analysing image software in combination with electron dispersive X-ray spectroscopy makes it possible to study the morphological properties, distribution and chemical composition of the copper droplets. The obtained results confirm the initial conclusions about size, distribution and composition of the copper-bearing particles. A large amount of copper particles is examined showing an obvious increase in their size from pit- to ladle cooling. The results show an increase in the average size of the droplets, which doubles from pit-cooling to ladle-cooling. There is a well-pronounced tendency of decrease of the percentage of droplets in the smallest fraction (<5 µm) in the ladle-cooled slag. In addition, the number of droplets in the larger fractions increases, compared to the ones in the pit-cooled slags. It is believed, that the developed methodology for analysis provides a relatively quick and reliable solution for comparison of the cooling rates in the slag. INTRODUCTION In the process of copper smelting and converting, iron-silicate slags are produced that contain various amounts of dissolved and entrained copper. Different physical and chemical techniques are employed for the valorisation of the remaining metals in the slag – magnetic separation, leaching, roasting, flotation, etc. According to Gorai et al (2003), about 2.2 tons of slag is produced per ton of metal. In 2016, about 20 million tons of copper have been produced globally (www.icsg.org). At an average of 0.5 percent copper content after treatment, these slags contain more than two hundred thousand tons of copper which is lost due to inefficient processing."

Jan 1, 2018