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By V. A. Luganov

Methods of treatment of pyrite concentrates differ, depending on the content of pyrite and non-ferrous metals: oxidation roasting, sulphatization roasting, smelting, direct hydrometallurgical treatment and so on. Existing technologies do not provide for high recovery of metals, expenses associated with existing technologies are high, and environmental issues, associated with the existing technologies need serious attention. We have developed universal technology of the activating-dissociating autogenous roasting of pyrite concentrates using air based, or air, enriched with oxygen, blow. The basic process is taking place in accordance with the following reaction: (1-x)FeS2 + (1-2x)O2 = Fe1-xS + (1-2x)SO2 +Q The products of this reaction are pyrrhotinized cinder and roasting gases, rich in SO2 (up to 18 % in case of air blow) and poor in SO3, that contain up to 1 % of elemental sulphur. Cinder contains different forms of pyrrhotite. These forms of pyrrhotite differ by its content (from Fe0.843S to Fe0.945S), thermodynamic, magnetic (from 4.10-1 to 3.6 SI units), flotation properties (with pyrite dissociation the ?-potential of the product is moving towards more electrically positive charge, from 0.95 for pyrite to 0.2 for dissociation products) and other properties that depend on the conditions of roasting. The combination of pyrrhotizing roasting with different methods of cinder treatment allows to increase the level of sulphatization of non-ferrous metals during the roasting; reduce the amount of blow used during the processing; reduce dust losses to the gas phase; reduce the capacity of gas cleaning system and increase resistance to corrosion of the gas-treatment system, used for the production of sulfuric acid from pyrites. This combination of treatments also allows to use magnetic separation and flotation for separation of ferrous and non-ferrous metal compounds during cinder treatment; perform de-arsenation of arsenic containing concentrates and by-products. Pyrrhotinized cinder may be treated by oxidizing and non-oxidizing hydrometallurgical methods. Keywords: Pyrite, polymetallic ores, sulphidization roasting, pyrrhotite, magnetic separation, arsenic sulphide

Sep 1, 2012

By Pan, Jian, Siwei Li, Deqing Zhu

"It is great significance to realize the efficiently and comprehensively utilization of iron, manganese and aluminum from refractory high-aluminum and high-manganese iron ores. Aimed at the two types of low grade refractory iron ores, mineralogical characteristics were studied. The direct reduction behaviors and evolution of mineral compositions of single iron ores and their blended ones were analyzed, and the corresponding reduction mechanisms were demonstrated. The results showed that only a part of iron oxides in high-aluminum ore are transformed to metallic iron after reduction, while the other react with aluminum and silica to form fayalite and hercynite which are difficult to be reduced. For the high manganese iron ore, most iron oxides can be reduced to metallic iron and manganese oxides can combined with aluminum-silica minerals to form galaxite and tephroite, promoting the reduction of iron oxides. Co-reduction results demonstrate that reduction of high- aluminum ore can be promoted by adding with high-manganese ore. Metallization and metallic iron grains increase dramatically by elevate high-manganese blending ratio. At the ratio of 60% high- manganese iron ore in the pellet feed, iron-slag separate well with a slag assaying 28.51%~36.35% Al2O3 and the recovery of iron and manganese can be reached 93%, respectively. The high-aluminum rich manganese residue was recycled with H2SO4. INTRODUCTION The growth of the Chinese iron and steel industry has been pushed forward by its rapid economic development in recent years, and 1126 million tons of iron ore have been consumed in 2014, where 933 million tons were imported according to the data from World Steel Association [1]. However, iron resources are limited, and especially the reserves of high-grade iron ores are declining, so it is of significant importance to optimize the mining rate of iron resources [2] and to utilize low- grade refractory iron resources, such as high-aluminum iron ore."

Jan 1, 2018

By J. Yianatos

The regrinding stage is necessary to achieve the particle size (liberation) for the final upgrade in the cleaning flotation process. At present, vertical mills (Vertimill) are employed at industrial scale, using small steel balls as grinding media. The regrinding process characterization requires mixing regime knowledge along with the mean residence time of the liquid and solid phases. The residence time distribution (RTD) and the actual mean residence time estimations from theoretical relationships are complex due to the presence of three components (solid mineral, balls and water), mass transport characteristics and segregation affecting solid holdup. Therefore, the experimental RTD determination is suitable for industrial mills. In this work, RTD measurements were performed in two different industrial flotation plants. Both plants operate with Vertimills of 1000-1500 HP in the regrinding process with different circuit arrangements according to the plant treatment capacity. The RTD was measured using the radioactive tracer technique. This technique allows for non-invasive tracer detection where the procedure consists of selecting a liquid (Br82 in aqueous solution) or solid (irradiated solid) tracer for RTD data acquisition in real time. The RTD was modelled by the Large and Small Tanks in Series (LSTS) model, which allowed the characterization of the different mixing regimes for both liquid and solids in the regrinding mills. Effective mean residence times in the range 2-11 min were obtained with RTD shapes similar to those obtained in tumbling ball mills. It was found that residence times of liquid and fine particles were similar, which is consistent with results observed in other mixing systems, e.g. mechanical flotation cells. Also, the mean residence times estimated from the RTD allowed the mass balance adjustment to be validated from metallurgical sampling data. RTD estimations are useful for better understanding the Vertimill behaviour and to identify the actual breakage rates. Keywords: vertical mill, residence time distribution, particle size, modeling

Sep 1, 2012

By N. N. Orekhova, I. V. Shadrunova, N. G. Novikova, N. ?. Volkova

The purpose of the research is scientific substantiation and formulation of strategy and technical solutions of handling liquid wastes of plants producing and refining copper-zink pyritic ores. In the course of research studied are chemical composition of technogenic waters of mining plants as well as water and alluvia of intake river within and outside a sanitary zone of Southern Ural mining plant using inductively coupled plasma mass-spectrometry and X-ray fluorescence analysis techniques. A particular focus is made on microcomponent composition. Novel data on Cd, Li, Be, Mn, Co, Cu, Zn migration with technogenic flows and accumulation of these elements in alluvia is obtained. It is showed that extraction of valuable components from technogenic waters is a novel problem for refiners that can be solved only in cooperation with mining industry ecologists. Laboratory research of selective copper and zink extraction into corresponding practical products by galvanocoagulation and sulphide precipitation is carried out. Common factors of phase formation are studied using physicochemical modeling, X-ray phase analysis and electronic microscopy. Methods of intensification of processes and increasing of extraction ratio of metals in products are elaborated. A technology of comprehensive processing of undersoil waters is proposed. Enlarged laboratory and pilot plant tests of technological solutions for protecting hydrosphere and extracting metals from mine waters carried out on several plants of UMMC-Holding Corporation showed a possibility of obtaining additional products having weight content of metal which is profitable for consequent metallurgical processing and purification of waters to comply with quality standards. A possibility of transformation of technological chain depending on season variability of water quality is put behind the designed technological schemes.

Jan 1, 2018

By L. Gao, X. Gui

Fine coal obtained from Kailuan mine served as the processing object of this study. This material was difficult to separate. A flotation rate experiment was designed to investigate the process distribution characteristics of size and density during fine coal flotation. Size and density analyses of five clean were studied. The mineral morphology of flotation rate experiment cleaning was observed through scanning electron microscopy. The fractions -0.074+0.045 mm and -0.045 mm exhibited the best practical floatability and presented the highest combustible body recovery rates, but the selectivity and natural floatability of these two fractions were the worst. The - 0.074 mm fraction has contaminated the clean coal from the early stage of flotation, and the cumulative clean coal ash of -0.074 mm reached up to 17.20%. The low and middle-density classes displayed varying flotation behavior, but the flotation yield difference was only nearly 3%. The middle-density class caused the clean coal to have high ash content. The poor selectivity of fine coals, middle-density fraction, and fine mud resulted in high-ash clean coals during flotation. Thus, improving the selectivity of fine coal, restraining the flotation of fine mud, and grinding the coal to decrease the middle density mass fraction to liberate clean coals can yield high-quality clean coals through flotation.

Jan 1, 2014

By Patricio Berrios, David Barriga, Peter Amelunxen, Gerson Sandoval, Roger Amelunxen

Laboratory test equipment and methods have undergone relatively little change since their introduction in the 1950’s. The Denver sub-A cell is still by far the most commonly used laboratory batch cell, but bottom-driven and instrumented cells are beginning to appear. Test procedures have also changed little over the past 60 years, and most engineers continue to rely on empirical models for predicted plant scale performance from laboratory scale tests. This approach is problematic, because changes in the froth phase characteristics in the lab hamper the reliability and reproducibility of the empirical extrapolation to plant scale. In a previous work, the authors reported on the impact of froth recovery at the laboratory cell, showing that variability in the froth recovery can lead to significant error in the modeled kinetic rate constant unless it is properly accounted for in the scale-up model. In this work, we review the role of hydraulic entrainment in the lab cell, and how variability in particle specific gravity, shape factor, and froth residence time can impact the entrainment recovery.

Jan 1, 2014

By A. J. Lynch, D. K. Tungpalan, Y. Reja, E. C. Avelar, G. Figueroa, S. Gómez, R. Alanis, M. A. Corona-Arroyo

"Have you been on a mine site? This question was posed by Emeritus Professor Alban Lynch to Higher Degree by Research (HDR) Students from the Sustainable Minerals Institute - Julius Kruttschnitt Mineral Research Centre (SMI-JKMRC) in the Student Technical Presentations in 2015. From that question, five HDR students from SMI-JKMRC organised a placement on mine sites in Mexico. The SMI-JKMRC is well known for its tradition to provide their students with opportunities to enhance and test their skills in mineral processing plants. The Student Venture became a short internship for HDR students which had the objective of establishing collaboration with mining companies in Australia and overseas, and of providing a unique experience for the HDR students in regard to their training, professional development, networking and cultural interchange. In return for the companies’ support, the students conducted plant audits to evaluate the process performance thereby providing valuable data to the host company. The 2016 Student Venture was held at the Grupo Peñoles & Grupo Fresnillo in Mexico, in which three mine sites received five HDR students from JKMRC and one young researcher from Universidad de Guanajuato (UG). This paper describes the positive outcomes for the mining company and the students for this experience. The Venture was considered very successful, as it provided valuable training for the students as well as in depth information about the operation of the comminution and flotation circuits of the host sites for the Grupo Peñoles & Grupo Fresnillo. The experience also provided an opportunity for an exchange of knowledge between the HDR students and the site personnel from the host operations. The indication of the success of the experience for all involved was the support of the host company in future student internships."

Jan 1, 2018

By Wei Sun, Chengwei Li, Zhiyong Gao, Yuehua Hu

"Grinding for mineral liberation is a prerequisite for a successful flotation separation. Different grinding media produce mineral particles with different morphologies and surface properties. In this study, the surface physicochemical properties of fluorite particles produced by ball and rod mills were systematically investigated through single mineral flotation experiment, wettability measurement, X-ray diffraction (XRD) test and scanning electron microscopy (SEM) observations. The XRD observations reveal that the surface exposure degree for both mill particles follows the order {111} > {110} > {100}. The difference lies in that the rod mill ones have a higher exposure of more reactive {110} and {100} surfaces, leading to a stronger interaction with the collector. The difference also leads to their higher elongation and lower roundness values of rod mill particles which are beneficial for the particle-bubble attachment by shorting the induction time. The wettability and flotation results show that the rod mill ones have a lower critical surface tension and a greater hydrophobicity when treated with the collector solution and accordingly perform a higher flotation recovery. This work, for the first time, revealed the importance of the exposure of crystal surfaces in determine the shape factors and reactivity of the mineral particles and will help provide guidance for optimizing flotation separation and particle surface modification. INTRODUCTIONFluorite (CaF2) is the most important source mineral for producing F-based chemicals and materials which are widely used in industrial, environmental, and medical fields [1, 2]. In ore deposit, there are two kinds of occurrence forms of fluorite mineral. Firstly, the fluorite mainly coexisted with the gangue minerals like calcite (CaCO3) and quartz (SiO2). Because of their similar density and fine-grained dissemination in ore deposit, ball mill grinding before flotation separation has been widely applied to produce relatively fine particles [3]. Secondly, the fluorite is often associated with other valuable minerals with higher relative density such as scheelite (CaWO4) and cassiterite (SnO2). Due to their obvious density differences and coarsely grained distribution in ore deposit, rod mill grinding before gravity separation has been usually used to produce more uniform particles and avoid over-grinding [4-6]. After the gravity separation, a flotation separation is also employed to beneficiate the fluorite [7]."

Jan 1, 2018

By Minna Päällysaho

For the first time, the idea of sustainable development was recognised at a high political level at the UN Conference on Environment and Development held in Rio de Janeiro in 1992 (UNEP, 1992). Then the governments of the world committed themselves to promote sustainable development in their national activities and international co-operation. In 2001, the European Council approved the EU Strategy for Sustainable Development (European commission, 2011). This complements and supports the EU?s so-called Lisbon Strategy (European council, 2000) on competitiveness. The revised Strategy for Sustainable Development was approved in June 2006. Recently sustainability has had an important role in policy and decision-making while the public awareness towards limits of the environment has been rising. However, the indicators of industrial sustainability satisfy primarily the needs of corporate management and global investors. The information is often broad and non-specific and might occasionally even give a false impression. Moreover, contradictions between environmental, economical and social aspects also point out the unreliability of existing sustainability indexes. Therefore, the current state of affairs serves the interests of neither the industry nor the policy makers. Current corporate sustainability indexes and indicator systems need to be assessed with scientific methods encompassing the identification of their strengths and weaknesses. This requires quantitative and qualitative assessment and synthesis of existing indexes and indicator systems, providing new data on the functionality of existing corporate sustainability indicators. Therefore, the assessment lays the foundation for the development of new, more balanced sustainability index. Our first aim in this multidisciplinary article is to analyse existing global sustainability indexes for process industry. Second, we will introduce a first version of a new sustainability index for process industry, which includes the environmental, social and economic impacts of the plant, as well as legislation aspects.

Sep 1, 2012

By A. I. A. Salama

In this paper, the problem of sedimentation and consolidation of poly-disperse suspensions is considered. The solid particles are assumed to be of different densities. If the sediment solids stresses are dropped out of the system equations and using the Richardson and Zaki hindered settling model, it has been found that in the limit, i.e., as time approaches infinity, the fluid is completely displaced to the top of the sediment zone. Furthermore, the species segregate completely with the heavier and coarser particles at the bottom of the sediment and the lighter and finer particles at the top of the sediment. Practical observations do not support these behaviors and physical-ly such behaviors do not exist; consequently, results of this kind in the literature are unrealistic. Here, a mathematical structure of the poly-disperse sedimentation and consolidation problem has been proposed. In this case the compaction zone species solids stresses are introduced in the momentum balance equations of the system. The species solid stresses in the sediment are constrained so that the system equations are consistent, i.e., sedimentation and consolidation of two or more identical species should behave as a mono-disperse system. Such a condition has not been recognized and imposed in some of the studies in the literature, which has led to unreliable results. Two practical forms of species stresses that satisfy the system consistency condition are here proposed. It should be noted that the study of sedimentation and consolidation of poly-disperse suspensions could result in more realistic suspension interfaces compared to mono-disperse suspensions, and could lead to more reliable engineering designs of tailings ponds. Predictions of sedimentation and consolidation in models of poly-disperse suspensions are demonstrated using published data.

Jan 1, 2014

By A. Y. Senchenko, S. G. Rybkin, A. V. Aksenov

"Oxidized nickel ores are important source for nickel production in Russia. Considerable explored reserves of oxidized nickel ores with relatively low nickel content, about 0.6-1.4%, are concentrated in the Ural region of Russia. Conventional process flowsheet with the use of blast matte smelting, applied in particularly by JSC “Ufaleynickel”, proves itself as extremely low-margin technology. This paper will examine development of a new more cost-efficient process involving integrated treatment of oxidized nickel ores using the ore from Serovskoye deposit as an example. Target products of this process are hydrate residues containing up to 15 % of nickel and 0.3 % of cobalt, as well as saleable salts of magnesium sulphate and ammonium suplphate. This innovative process includes roasting of a mixture composed of ground ore and sulphuric acid at 650 °?. Sulphate roasted product is then leached in a weak sulphuric acid solution with the following separation of liquid from insoluble solids. Sulphate solution is neutralized by aqua ammonia in two stages until media pH is 3.0-3.5 and 7.5-8.0 with detachment of iron- and nickel-bearing hydrate residues respectively. The mother solution is boiled out resulting in salt crystals which are then dried and roasted at 500-600 °? to obtain magnesium sulphate. The gases generated during salts roasting are captured with production of ammonium sulphate. The developed technology demonstrates higher potential in terms of its economics and eco-efficiency comparing with the conventional process. This innovative technology for integrated process of oxidized nickel ores was patented in Russia.INTRODUCTION Development and industrial implementation of efficient technologies to process oxidized nickel ores is a very important task for non-ferrous metallurgy of Russia. The main reasons for the required technical upgrade of the plants processing oxidized nickel ores is depletion of rich ores, increase of energy resources costs, amplification of environmental and production standards. Due to this, transition from conventional pyrometallurgy to cost-effective hydrometallurgical technologies of ore liberation and solutions processing is logical and corresponds to the worldwide practice of Ni production from oxidized nickel ores."

Jan 1, 2018

By Y. M. Zhu

Lead in environment often causes a serious health hazard. The removal of Pb2+ from aqueous phase is a beneficial project. In this paper, deposited Saccharomyces cerevisiae (S.c.) was chosen as adsorbent, Pb2+ ions as adsorbate, and the process of biosorption was studied. The dynamics of the adsorption was investigated. The adsorption mechanism of Pb2+ by S.c. cells was also investigated by detecting microstructure, zeta potential under different pH value, FT-IR spectra of the S.c. particles before and after biosorption. It was shown that the biosorption of Pb2+ by deposited S. c. is a rapid process, and the adsorbing equilibrium is reached within 10 minutes. The Zero point of zeta potential of S.c. cells is pH=3.3. When 2.0<pH<3.3, there exists biosorption (biosorption rate 76%~88%), which means static bio-sorption been not the only kind of biosorption. FT-IR spectrum analysis showed that groups on bacteria surface were mainly characteristic groups of protein and amylase; oxo-groups and nitric-groups on S.c. cell surface could chelate with heavy metal ions. Chemical adsorption might exist in the process.

Jan 1, 2014

The energy dispersion X-ray fluorescence (EDXRF) analysis technique is a rapid and accurate method for describing sample?s element component and percentage composition. On the base of profound research for the national and international development and research condition, the author researched the EDXRF analyze technique and the EDXRF analyzer?s principle in depth, the difficulties and the key points for research and development of EDXRF analyzer; gave a scheme for re-search of bench EDXRF analyzer; researched some algorithms used in energy spectrum analysis; developed the energy spectrum analysis software based on the Visual C++ 6.0; together with the energy spectrum analysis software, the author designed and processed the structural of the bench XRF analyzer and integrated the import X-ray tube, thermoelectrically cooled Si-PIN photodiode X-ray detector and pulse amplitude analyzer as a model machine. The result shows: The model machine can be used in multi-element analysis at the same time for different types of dry mineral samples, with fast analysis speed, accurate model and high stability.

Jan 1, 2014

By Xinyang Xu, Chen Zhang, Lixia Li, Zhitao Yuan

"Density functional theory was employed to clarify the mechanisms of the activation of a quartz surface and its collection by the flotation method at the molecular level. The calculation results indicated that hydrogen bonds on the quartz surface (1 0 1) existed in pairs while in contact with water. The simulation was carried out to investigate the different effects of Ca2+ and Ca(OH)+ on a quartz surface with hydrogen bonds, and the results suggested that Ca(OH)+ most likely adsorbed onto and activated the quartz surface. Mulliken population analysis of the external oxygen atom of the quartz surface, calcium atom of Ca(OH)+, and the oxygen atom of oleate showed that there were electron transfer and the formation of a chemical bond between Ca1-O1 and Ca1-O3, which were indicative of strong interactions between the three atoms. In addition, the –OH of the Ca(OH)+ contributed to the activation, which suggested that the Ca(OH)+ group acted as a bridge between the surfaces of oleate and quartz.INTRODUCTIONFlotation is an effective separation method in mineral processing that takes advantage of the physicochemical differences between minerals and gangue, and the properties of the mineral surfaces play a key role in this process (Liu et al. 2016, Qin et al. 2017). In the reverse flotation process of iron ore, gangues are captured by cationic or anionic collectors and floated with air-bubbles as tailings, and the pre-depressed iron oxide minerals are left at the bottom as concentrates (Lima et al. 2013, Yianatos et al. 2015, Zhu et al. 2015). Quartz (SiO2) is one of the major gangues of hematite ores and cannot be easily removed. It is a naturally hydrophilic mineral, in which silicon is the cation in its crystal structure and has very limited solubility. Therefore, quartz must be activated, usually by metal ions, for its effective rejection as a float-product by reverse flotation (AIME. et al. 1976)."

Jan 1, 2018

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

"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. 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."

Jan 1, 2003

By Alexander V. Epiforov, Stanislav V. Balikov

This paper describes of processing tests of 8 flotation concentrates containing precious and base metals by pressure oxidation (POX) method. Concentrates 1 and 2 were gold-copper concentrates. Zinc and silver were by-products in these concentrates. These concentrates were processed by POX with following cyanidation of POX solid residues, copper solvent extraction and zinc carbonate precipitation. The recoveries of gold, copper, silver and zinc from these concentrate were 98, 99, 30 and 99%, respectively. Concentrates 3 and 4 were lead-zinc concentrates. Silver was by-product in concentrate 3. Gold, silver and copper were by-products in concentrate 4. Concentrate 3 was processed by POX with following reduction smelting of POX cakes for primary lead recovery and zinc carbonate precipitation from POX solution. The recoveries of lead and silver into ingot were 96 and 98%, respectively. The recovery of zinc was 99%. Concentrate 4 was processed by POX with following zinc carbonate precipitation and reduction smelting of POX cakes. Copper was precipitated from the POX solution using sodium sulphide prior zinc precipitation. The recovery of zinc into carbonate concentrate was 99%. The recoveries of lead, gold and silver into lead bullion were 95, 99 and 98% respectively. The recovery of copper into sulphide concentrate was 99%. Concentrate 5 was gold-pyrite concentrate, and concentrates 6-8 were double refractory gold-arsenopyrite concentrates. Silver was by-product in these concentrates. These concentrates processed by POX and CIL. The recovery of gold from concentrate 5 was 98%, and from concentrates 6-8 was 85-90. Low gold recovery from concentrates 6-8 was associated with preg-robbing factor. The recovery of silver from gold-sulphide concentrates did not exceed 10-20%. The low silver recovery was associated with argentojarosite formation that is resistant to cyanidation. The flowsheets for complex processing of precious and base metals sulphide flotation concentrates based on this test work results were proposed.

Jan 1, 2018

By Vasile Murariu, William Pate, John Herbst, Dilek Alkac

"Multiphysics models are essentially first principles models capable of providing very accurate micro scale predictions. The computational requirements for Multiphysics Models are extensive, precluding their direct use for flowsheet simulations. Population balance models get their form from theory but the model parameters have to be provided from experiments. The prediction errors for the population balance models are typically significantly higher than those for the Multiphysics Models but the computational effort for Population Balance Models is typically much less than that for the Multiphysics models. The hybrid model described here takes advantage of the strengths of each of the two primary model types and minimizing the weaknesses of each. The Multiphysics Model is used to perform high accuracy "experiments" that are difficult or impossible to conduct in laboratories or plants. The results of these experiments are combined with standard laboratory or plant data to parameterize and further enhance the Population Balance portion of the hybrid model. The creation of a useful Hybrid Model is demonstrated for a MP1000 secondary crusher. The validation of the hybrid crusher model is also presented. Finally the use of the Hybrid Model is illustrated in a full comminution flowsheet simulator."

Jan 1, 2014

The status quo of ecological rehabilitation in metal mine in China and progress in the technology for ecological rehabilitation are presented, including soil reconstruction, soil improvement, plant selection. The present and future research fields are suggested: basic theory of ecological rehabilitation, operative technology of ecological rehabilitation, new technology application research and ecological rehabilitation plan, management and policy.

Jan 1, 2014

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 H. Wotruba, L. Gronen, A. Hellmann, S. Sindern, J. Katzmarzyk

"This paper focuses on the beneficiation of the REE-Y-Nb-Zr complex ore from the ‘Khalzan Buregtei’ deposit, Mongolia. Pre-concentration based on mineralogical studies was investigated at the Unit of Mineral Processing (AMR) and the Institute of Applied Mineralogy and Economic Geology of RWTH Aachen University. In order to minimize the energy consumption in the most energy intensive grinding process a pre-concentration process using dry magnetic separation of particle sizes coarser than required for the liberation of the valuable ore minerals was designed. Dry magnetic separation in the particle size range of 63-250 µm is suitable as the pre-concentration method, due to the intergrowth of REE-Y-Nb-Zr bearing minerals with magnetic minerals determined by QEMSCAN© analysis. The results showed that a mass reduction of 45.3 wt.-% at high recoveries of REE, Y, Nb and Zr (90 wt.-% and higher) in the pre-concentration product was achieved at the beginning of the process chain. The improvement of process efficiency as shown in this study depends on the abundance and association of minerals affecting the magnetic properties (e.g. hematite) of the ores. Therefore, these mineralogical parameters are as important as grain size and ore grade for the geometallurgical evaluation of potential mining operations at ‘Khalzan Buregtei’.INTRODUCTION Polymetallic deposits containing other critical elements besides REE have the advantage of being robust to economic development and fluctuations of individual metal prices. (Gronen et al., 2016). These deposits can host economic grades of heavy and light REE, Y, Nb, Ta, Zr in complex mineralogical compositions. About 120 deposits of this type are known worldwide, including ‘Norra Kärr’ in Sweden, ‘Strange Lake’ in Canada and ‘Khalzan Buregtei’ in Mongolia which are not valued economically yet. (Salvi. & Williams-Jones, 2004.)"

Jan 1, 2018