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By V. A. Vorob'ev, A. N. Larionov, E. N. Ivanov, M. A. Ryazanov

The aim of the research is to increase the recoverable value of poor, difficult-to-digest complex mineral raw materials. In the Republic Belarus, universal centrifugal-shock devices have been created for crushing, grinding and classification of ore and non-metallic mineral raw materials in dry mode, which differ from foreign analogues by a higher level of resource saving (including electricity and materials). Dry-ore preparation technologies have been tested on a pilot scale: fine crushing (replacing grinding in rod mills), grinding (replacing wet grinding in ball mills) and pneumoclassification on different types of ores, - which made it possible to identify the criteria for the suitability and unsuitability of mineral raw materials for their use. The possibility of regulating the upper and lower limit of the size of the finished material is established, the possibility of reducing the yield of slimes (-0,020 mm) to 5 times is determined. A comparative analysis of the contrast degree of separation characteristics of ore a similar granulometric composition, crushed in wet and dry conditions, is performed. The achieved contrast degree of gravity properties after dry grinding - 104,3; after the wet - 60.2. When enriching on a centrifugal concentrator, gold recovery to the concentrate after dry grinding increased by 13.12% while improving the quality of the concentrate from 78.3 g/t gold to 90.75 g/t. When testing the gravity-flotation scheme for the enrichment of poor gold-quartz ore, the increment of gold extraction after dry grinding was 7.6% for gravity and 9.5% for flotation; the total increase in extraction is 17.1%. The possibility of flotation of a larger material after dry grinding has been proved, with an extraction gain of 1.5% compared to the flotation of thinner material after ball milling. The influence of dry technology on the efficiency of the leaching of gold and silver (an extraction gain of 5.5 to 10%) and heap leaching (extraction gain - up to 18.3%) was studied. The positive influence of dry ore preparation technologies on the efficiency of gold and silver heap leaching and heap leaching, thickening and filtration is proved. Lines of dry ore preparation technologies can be used in modular complexes for processing technogenic raw materials.

Jan 1, 2018

By Jun Xiao, Yucai Zhou, Yanhong Dong, Daixiong Chen

"In this article research on the mineralogical characteristics and beneficiation process for a copper molybdenum deposits in Heilongjiang province of China has been carried out. Chemical analysis, X-ray diffraction(XRD) and Quantitative Evaluation of Minerals by SCANning electron microscopy (QEMSCAN) were conducted on samples. The bulk analysis results showed that: (1) Comprehensive recovery and separation of molybdenum & copper minerals was feasible by the flowsheet of first copper-molybdenum mixed flotation after grinding the ore samples to 61.88% -74µm and then separation flotation of copper and molybdenum after regrinding the Cu-Mo mixed concentrate to 83.26% -38 µm. The results highlight relationship between mineralogical characteristics of ore and comprehensive benefication method. (2) the combination of "" Sodium sulphide and sodium thioglycolate "" reagents are effective inhibitors of copper-molybdenum mixed concentrate, their selectivity performance is better than that of single reagent. Good flotation indexes were gained that might be directive experience to similar cases. KEYWORDS Mineralogical characteristics; molybdenite; chalcopyrite; flotation separation; inhibitor INTRODUCTION Copper and molybdenum metals are widely used in the field of metallurgy, aerospace, national defence, etc. Copper –molybdenum sulphide ore is an important source of copper and molybdenum metals. At present flotation is still the preferred methods to deal with the copper-molybdenum sulphide minerals (Yin, Z., Sun, W.et al. 2017; Ansari, A., & Pawlik, M. 2007; Hirajima, T., Miki, et al. 2017). Copper and molybdenum sulphide ores usually have the similarly good nature floatability(Miki, H., Matsuoka, et al. 2017), meanwhile most molybdenum sulphide ore has tiny grained-size(Castro, S., & Laskowski, J. S. 2015.) and closed relationship with other sulphide and gangue minerals which result in the coper and molybdenum separation problem. Base on the nature of the ore and flotation properties of the individual minerals contained in the ore, there are two methods are usually used to deal with the copper – molybdenum ore, including bulk molybdenum/copper flotation followed by separation of copper and molybdenum minerals, sequential molybdenum/ copper flotation(Liu, G. Y., Lu, et al. 2012). The latter method has the shortcoming of hard to activate the depressed copper minerals in the previous molybdenum flotation process, which may result in a large loss of the copper from concentrate, this disadvantage would avoid while adopting the former method. bulk flotation followed by separation process is to get the copper-molybdenum concentrate from raw ore first then separate flotation the molybdenum and copper minerals, benefit from the excellent floatability of both molybdenum and copper minerals ( Malhotra, D., Rowe, R. M., & Bhasin, A. K. 1986; Cao, Z., Yue, et al. 2017 ), it really easy to obtain the mixed concentrate. In order to get the high quality copper and molybdenum concentrate, the key technologies and difficulties are to realize the separation of the copper and molybdenum minerals which have the very similar natural floatability (Raghavan, S., & Hsu, L. L. 2015; Nakhaei, F. 2014)."

Jan 1, 2018

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 M. Evertsson, M. Johansson

"In minerals processing control is vital to increasing performance and output of a plant. Model predictive control (MPC) is one of the most effective control strategies used in process industry. Sbárbaro (Sbárbaro and Del Villar, 2010), Asbjörnsson (Asbjörnsson, 2015), and Légaré (Légaré et al., 2016) have for example highlighted the possibility to simulate, develop and tune control systems using plant simulators within minerals processing. In more recent years the use of model predictive controllers have increased, and many process industries now utilize more advanced control methods to regulate their processes, raising the question regarding how to, build, test and verify a proposed control solution successfully. In this research, a linear model predictive controller is formulated and applied to a simulator of an existing tertiary crushing circuit. The circuit has in previous work by Johansson (Johansson, 2017) been modeled in MATLAB Simulink and calibrated relative plant data to an average error of less than 10% over 8 hours of production. The work demonstrates how to formulate the controller model structure to describe conveyor belts, storage components, screens, crushers, and control objectives for a minerals processing circuit. The work illustrates how to apply and successfully evaluate possible upsides in a circuit. The advantage of a crushing circuit simulator is that it can be configured, tuned and modified in any possible way, which is of great benefit to developers and engineers. Additionally, examples of how to use estimated measures to improve the performance of the plant are demonstrated. The control performance is finally evaluated for three different controller configurations."

Jan 1, 2018

By Jingzhong Kuang, Zheyu Huang, Chuanzhou Guo, Pengfei Liu

"In this paper, scheelite and scheelite coated with Pb2+ (SC) were synthesized by chemical precipitation with the help of ultrasonic. The role of the Pb2+ on scheelite was evaluated. Additionally, the dissolution behavior of minerals and the adsorption mechanism of collectors were investigated systematically via SEM, XRD, EDS. The results indicate that the ultrasonic cavitation can promote the formation of scheelite with large particle size and high crystallinity. Due to the exchange of WO4 2- and OH-, the dissolution of scheelite are not in a 1:1 equivalent amount by chemical formula and the concentration of WO4 2- is higher than that of Ca2+ in the solution because Pb2+ promotes the transfer of WO4 2- from scheelite surface into the solution. The dissolution of scheelite is an endothermic reaction and its enthalpy reaches the maximum value of 692.59J·mol-1 at pH=8~10. But the coating of Pb2+ changes the thermal effect of scheelite in the solution and the dissolution of SC is an exothermic reaction with the dissolution enthalpy of -262.30 J·mol-1. At pH=8~10, the adsorption capacity of sodium oleate and salicylhydroxamic acid on the surface of SC is higher than that of scheelite which delivers that Pb2+ contributes to the scheelite surface dissolution and enhances the adsorption of collectors on the mineral surface, thus achieving activation.INTRODUCTIONIn modern society, tungsten is a type of quite important rare metal and also a strategic resource. Because of its low vapor pressure, high melting point, good electrical and thermal conductivity properties, it is widely applied in high-temperature technology, lighting, machine and engine construction (Zhao,Z.W, 2013; Yan, W, 2017; Ilhan, S, 2013). Both scheelite and wolframite are the major tungsten deposits. With the depletion of easily-processed wolframite, scheelite has drawn a great deal of scientific and industrial attention. Scheelite can be recovered by flotation due to the metathesis of polarity and chargeability on minerals surface via adding regulators and collectors."

Jan 1, 2018

By M. Gonzalez Fernandez

"Commercially introduced in 2004, the SAGDesign™ test has today proved its efficiency for sizing SAG mills for a wide variety of ores, from very soft to very hard ones. The interest of building a model using the SAGDesign™ test specific energy is the introduction of such a model into a complete process simulator making it possible to predict a complete material balance. The developed model compares the required specific energy with the energy provided by the mill. This energy calculation is derived from the Austin Power Formula. The specific energy provided by the test is corrected, using various parameters, such as the Ball Mill Work Index, to take into account the true operating conditions, the feed and product sizes. The core of this model allows the determination of the product d80 using the mill geometry, its operating conditions and of course the SAGDesign™ test results. To be included in a simulator, the model must also predict the overall size distribution of the SAG mill discharge. Assumptions to answer this point are presented here. The model has been implemented in the USIM PAC simulator. It is used either to predict the product size distribution for a given SAG mill, but also to size a SAG mill for getting a required reduction ratio. INTRODUCTION Over the last few years several types of new comminution machines have been introduced in the market. The most notable newcomer was the HPGR (Morley, 2006). But, even when these machines have some advantages, they have not earned the trust of the mining industry. That is why the established technologies still being the first choice. And, in comminution, that first choice are SAG and ball mills. The design of ball mills has been well understood for a long time. The Bond Ball Mill Work Index is the standard test which helps to describe the ore in terms of energy requirements for milling. Unfortunately, the development of an equivalent test to characterize the ore subject to SAG milling has taken some time. As of today, several tests are available in the market, like the MacPherson test, the MinnovEX SAG Power Index (SPI™), the JK Drop Weight Test, the SMC Test® and the SAGDesign™ test (Verret et al., 2011). The SAGDesign™ test, developed by John Starkey in Canada in the early 2000s (Starkey et al., 2008, 2015), has become one of the standards to assess the grindability of an ore in a SAG mill. One of its advantages is the reduced sample mass needed to perform it, hence, the reduced cost. The second one is that the output of the test is straightforward, it is the energy required to grind the ore between two sizes. Because of this energetic approach, the results provided by the test can be directly applied to size a new mill or to assess the performance of an existing mill."

Jan 1, 2018

By D. DePaoli, P. Zhang

"Phosphate ore is one of the most significant secondary resources for rare earth elements (REEs), and Florida phosphate is of particular interest due to its much higher ratio of heavy REEs, especially yttrium. Analyses of numerous samples from different phosphate processing streams in Florida showed that heavy REEs account for about 50% of the total REEs in Florida phosphate with yttrium accounting for approximately 30%. It was estimated that the amount of yttrium from US phosphate processing could meet the world demand for this critical element. This research aimed at recovering both REEs and phosphorus from a phosphate flotation tails. This tails is composed of mainly silica and phosphate with a small fraction of heavy minerals including monazite and xenotime. Since the specific gravity of silica is 2.6 versus 3.2 for phosphate and 4.5-5 for rare earth minerals, pre-concentration of the minerals of interest by gravity separation was investigated first. A pilot scale shaking table was used in this study. One pass gravity concentration achieved a shaking table concentrate analyzing over 600 ppm REEs at about 40% recovery. Flotation of the shaking table concentrate resulted in a product containing 1809 ppm REEs and 26.37% P2O5 with corresponding recoveries of 73% and 82%. Sulfuric acid leaching at 75oC could recover over 60% REE and nearly all the P2O5. Higher REEs (>90%) recovery was achieved by conducting leaching at higher temperature with concentrated sulfuric acid. The phosphoric acid from leaching of the flotation concentrate is of superior quality compared with that generated from regular phosphate rock.INTRODUCTION Rare earths are a group of 17 elements including those of the lanthanum series, as well as the non-lanthanides, yttrium and scandium. These elements have very specific critical uses in a multitude of markets. For example, lanthanum is used as a catalyst in breaking down crude oil to produce gasoline, diesel and jet fuel and neodymium is the core magnetic component in high-strength magnets for electric car batteries, wind turbines and hard disk drives. Rare earths are also essential for many military applications. Many of these applications have no substitute materials and the move to green technologies has dramatically increased their demand."

Jan 1, 2018

By I. Westermann, K. Marthinsen, M. S. Remøe

"Al-Mg-Si alloys often add small additions of e.g. Mn or Cr, to form dispersoids, which may act as nucleation sites for Mg2Si particles after homogenization. The purpose is to ensure a high density of uniformly distributed small ?’-particles, which can be dissolved during further processing prior to the final age hardening step. However, their density and spatial distribution are critically dependent on the homogenization procedure. It is therefore important to have a robust and reliable method for assessing their spatial distribution. In the present work an existing methodology for assessing spatial uniformity, the Global Shannon Entropy (GSE), has been implemented and evaluated for different dispersoid structures characterized by scanning electron microscopy. This metric is highly dependent on the parameters used, but by careful selection of adequate parameters, it can be effective in detecting non-uniformity. An important weakness with the GSE was identified, and a modification to improve on the ability to differentiate degrees of non-uniformity is suggested. To evaluate the proposed methodology, the effect of heating rate on dispersoid precipitation behaviour during homogenisation of four Al-Mg-Si alloys with different Mn/Cr-content has been investigated. The metric with the new term has demonstrated promising results, and improved the ability to differentiate degrees of spatial uniformity.INTRODUCTION Al-Mg-Si series alloys are the most common aluminium extrusion alloys and are attractive for applications in a range of sectors (e.g. construction, automotive and recently also in consumer electronics), due to their generally good combination of strength, ductility and corrosion resistance. However, their extrudability and end properties depend critically on the alloy chemistry as well as prior processing conditions. Coarse ß-AlFeSi or Mg2Si-particles typically have a detrimental effect on extrudability, while small dispersoid particles may affect recrystallization, grain growth and precipitation of Mg and Si. The strengthening potential in the final age hardening step depends strongly on the amount of Mg and Si in solid solution after extrusion. The manner in which these particles are spatially distributed will decide whether the final product will exhibit uniform properties, and the number density and sizes will determine the extent of the effect. As such, these are important characteristics."

Jan 1, 2018

By M. Fig, J. Brune, C. Strebinger, G. Bogin

"A fundamental understanding of flame propagation characteristics through and around obstacles is needed to accurately model methane driven longwall coal mine explosions originating or propagating in the gob. Experimental investigations of methane flames in horizontal cylindrical reactors with simulated gob (i.e. rock piles) were carried out alongside coupled Computational Fluid Dynamics (CFD) and combustion simulations. Stoichiometric methane-air mixtures were ignited in semi-open reactor vessels of 5cm, 9.5cm and 71cm diameter, all with a fixed length to diameter (L/D) ratio of 8.6. This was done both with empty reactors and also with a rock pile placed at the open end of the reactor. The rock pile length to reactor length ratio was fixed at 0.3, and the rock pile height to reactor diameter ratio was fixed at 0.33 for all reactors. The smaller two reactor experiments were modeled with ANSYS Fluent in 2D. Experimental results indicate that for this geometry a similar acceleration mode occurs across scales: that the flame speeds up an average of 40% as it passes over a rock pile with this profile. The model is able to capture several important features of the experimental results, including the significant increase in velocity, the speedup ahead of the rock pile, and the leveling off of the empty tube flame front propagation velocity. INTRODUCTION Explosions in underground coal mines are among the largest industrial explosions, known to result in the rapid combustion of 20m3 of fuel gas or more [1,2] Coal beds hold methane gas under pressure, and when the pressure is relieved through mining activity some of this methane is released. The methane then mixes with ventilation air and, if not sufficiently diluted, may form a combustible mixture, which may result in an explosion. Several large coal mine explosions have occurred around the world recently. These include the 2014 Soma Mine disaster in Turkey that killed 301 people [3], and the 2009 Heilongjiang Mine explosion in China that killed 108 [4]. Other recent mine explosions, including the 2010 disaster at the Upper Big Branch mine that caused 29 fatalities [5], have demonstrated that explosive gases can accumulate and ignite within and around the gob area of a longwall coal mine and then expand into the active mining face and nearby areas, endangering workers and equipment. If enough combustible gas is involved, the initial flame can accelerate, eventually transitioning from deflagration to detonation [6]. Researchers are developing a fundamental understanding of the evolution of the explosion process from the laminar kernel to the fully turbulent regime, and its propagation through obstacles such as those found in the gob. Researchers also studied the initial development of methane flames and the potential for the development of a detonation."

Jan 1, 2018

By K. Ihara, T. Yamaguchi, K. Matsumoto

"Al-Fe alloy sheets having layers with different strain components were produced by unlubricated hot rolling and the recrystallization texture formation during annealing was investigated in each layer. In this study, the strain component introduced by rolling was quantitatively evaluated by measuring degree of bending of an aluminum pin embedded in the sheet. The textures before and after annealing were investigated by the SEM-EBSD technique. It was clarified that, in the middle layer, where comparatively small shear strain was introduced, ß-fiber subgrains and cube {001}<100> oriented subgrains were formed before annealing, and cube oriented recrystallized grains grew after annealing. On the other hand, in the surface layer, where large additional shear strain was introduced, shear texture components and cube oriented subgrains were formed before annealing, and shear texture was retained even after annealing, while cube oriented subgrains did not grow and were encroached. It was suggested that introduced strain components influenced the recrystallization texture formation by inducing different distribution of the subgrain size, stored strain energy and orientation relationship with surroundings before annealing.INTRODUCTION The microstructure developed during the hot-rolling process of aluminum and aluminum alloys affect the mechanical properties of the final product sheets. Especially, the crystallographic orientation in the final product sheets affects the r- value and ears during deep drawing (Humphreys & Hatherly, 2004), then the texture control in the hot-rolling process is important. When the friction between the rolling roll and rolled sheet in the hot-rolling is large, both the rolling texture and recrystallization texture tend to be heterogeneous in the thickness direction. It is known in many rolled aluminum alloy sheets that the texture in the surface layer was different from that in the middle layer because of additional shear strain. It was reported that in the vicinity of the surface layer, where large additional shear strain was introduced, the shear texture <1 1 1>//ND and < 1 1 0> // RD which contain components of {1 1 1} <1 1 0> and {0 0 1} <1 1 0> developed during rolling, and the shear texture developed even after recrystallization annealing (Sakai et al., 2002). Particularly, it is thought that the <1 1 1> // ND texture contributes to improve the r-value and press formability (Inoue & Takasugi, 2007). Therefore, asymmetrical rolling and high friction rolling have been applied to improve formability of aluminum alloys by adding shear strain in the rolled sheets as deep as possible (Kamijo et al., 1972; Inoue et al., 2005). However, few researches have been focused on the microstructures and texture before annealing and thus, the detailed mechanism is still unclear how the texture after annealing is affected by the texture before annealing. In this study, the Al-Fe alloy of commercially pure aluminum was chosen as the first material to be studied in order to clarify the fundamental process of the recrystallization texture formation. The main purpose of this study is to clarify the effect of additional shear strain on the rolling and recrystallization textures in the hot-rolled sheets by analyzing the transition of microstructure and orientation distribution through recrystallization annealing."

Jan 1, 2018

By H. X. Yan, J. X. Zhang, F. S. Niu

"The analysis on influencing factors of hydraulic conditions in fine hematite flocculation, such as stirring speed, stirring time and axial distance of particle size and fractal dimension of floc was investigated. Furthermore, response surface methodology(RSM) has been applied according to the Box-Benhnken center-united experimental design principle to optimize parameters of hydraulic conditions as a response index to indicate the fractal dimension of floc. The results show that when the agitation speed is 900r/min, the axial distance is 2.0cm, and the stirring time is 3.0min, the particle size reaches the maximum value of 35.44µm and the fractal dimension is 1.6594. The interaction between the axial distance and the stirring speed is highly significant, but the interaction with the stirring time is not obvious. The experimental data and model predications match well, which indicates that the established model has high accuracy and practicability. INTRODUCTION With the exhaustion of iron ore resources that are easy to be mined and the vigorous demand for iron and steel, the exploitation and utilization of fine-grained embedded iron ore resources have drawn attention from the industry and the government [1~2]. Flocculation flotation is one of the effective methods for separation and recovery of fine granular minerals. In 1975, the method was first applied and succeeded in Tilden Concentrator, USA. Flocculation and desliming became the key technology of the Tilden to raise its annual treatment capacity from 4 million tons to 8 million tons at that time [3 ~ 4]. In 2008, the selective flocculation and desliming-reverse flotation technology was successfully used to treat 2.8 million tons of Qidong iron ore. Under the conditions of 28.36% raw iron grade and 98% grinding fineness -0.038 mm, the ideal index of 62.5% iron concentrate grade and 68% recovery was obtained [5]. Dr Kitchenner of the Royal College of Mining and the Ore Processing Research Group of Wallenstein Laboratory first proposed the use of flocculation to separate minerals. After that, many scholars conducted a great deal of theoretical and practical researches, but mostly they focused on chemical theories, mathematical models and selectivity differences in the flocculation process, while the research on the influence of the pulp flow state on the separation effect in the flocculation process started later [6~9]. The results show that the motion of the agitated flow field has a significant influence on the formation of flocs. The fluid morphology will change with the change of hydraulic conditions. The change of fluid morphology will not only affect the movement behavior of particles, but also change the action of chemical agents on the surface of mineral particles[10~12]."

Jan 1, 2018

By X. H. Li, F. Xie, Q. Zhang, Z. H. Shen, S. Mao

"There is abundant rare-earth element(REE) in our country, but it is very fragmented in the earth's crust, and it is very difficult to mining or mining cost is extremely high. There are few of industrial value rare-earth deposits. There is a lot of concomitant rare-earth deposits, and the comprehensive utilization value is high. There is very rich carlin-type gold resource, associated with a certain amount of REE in the southwest of Guizhou province. In order toutilize comprehensively the resources, this paper conducts the study on the occurrence characteristics of REE in the ore. By the chemical analysis, the gold grade is 3.35g/t, the organic carbon 0.81%, the total REE 0.022%, which is a high carbon fine disseminated gold ore. By the optical microscope and XRD analysis, the major minerals are quartz, pyrite, calcite, limonite, arsenopyrite, mica, kaolinite, clay minerals, etc. In addition, there is a large amount of carbonaceous materials, such as organic carbon, graphite, which is harmful on leaching of gold. By the scanning electron microscopy analysis, there are thorium, lanthanum and neodymium, ytterbium, persimmon and other REE in the ore. Gravity separation shows that REE could be enriched to lighter material mainly, which indicates that REE disseminate closely with lighter materials.INTRODUCTION Carlin-type gold ore is important gold resource in the world, which are mainly distributed in Nevada and its vicinity, as well as the two Golden Triangle of Yunnan, Guizhou, Guangxi and Sichuan, Shanxi, Gansu province in China(Su W.C. et al.,2009; Xia G.X.,1996).Guizhou carlin-type gold ore is the second largest gold resource in the world(Muntean J L et al.,2011), distributing along the southwestern margin of the Yangtze plate, mainly mineralizing in the neopaleozoic-early mesozoic(Xie Z J et al.,2017). Many large gold deposits have been found in southwest in Guizhou in twentieth century, such as Zimuyou,Getang, Lannigou, Shuiyindong and Laowanchang gold deposit, and so on, and the gold reserves reach over 100 tons(Xia Y. et al.,2009).There is a certain amount of rare-earth resource in the carlin-type gold ore in the southwest in Guizhou province, and the current researches might mainly focus on characteristics of REE from the angle of geological mineralization(AnanyevY.,2015), not from the angle of separation and enrichment."

Jan 1, 2018

By Yuhua Wang, Haitao Zheng, Guangli Zhu, Yuehao Zhao, Fushun Yu, Dongfang Lu

"Spodumene, feldspar and quartz possess similar surface properties, which make the difficult to separate spodumene from other silicate minerals by flotation. The differences of crystal structure, surface property and floatability of three minerals were studied by various technical means. The results show that Li-O and Al-O bonds in spodumene structure are not strong and easy to be broken. However, Al-O and Si-O bonds in feldspar and Si-O bond in quartz are very strong and not easy to be broken. High contents of Al and Li on spodumene surface were found by XPS measurements, which is benefit for the adsorption of anionic collector. The surface energies of main cleavage planes of spodumene (110), feldspar (001) and quartz (001) are 1.88 J/m2, 2.97J/m2 and 2.68J/m2, respectively. Hence, the exposed surfaces of feldspar and quartz are not saturated and easy to adsorb OH- ions from solution and cause the lower IEP than spodumene. The contact angles of three minerals in water are lower than 16º, suggesting that the hydrophilicity of three minerals is high, and the order of hydrophilicity is quartz > feldspar >spodumene. Correspondingly, contact angles and flotation recoveries of spodumene are bigger than that of feldspar and quartz in presence of a combined anionic and cationic collector named YOA.INTRODUCTION Flotation technology plays most important role for the recovery of spodumene from pegmatite ore. Generally, spodumene with fresh surface is easy to be floated using soap and oleic acid as collector, and the best flotation pH range is 4.0 to 9.0. However, the flotability of spodumene will become worse when its surface was polluted by slime which produced by the weathering of spodumene and other silicates (Dresler et al. 1998; Moon and Fuerstenau 2003; Menéndez et al. 2004; Yu et al. 2015). In addition, the species of Ca2+, Fe3+, Mg2+ and other metal ions in pulp can not only activate the flotation of spodumene, but also the activation of gangue minerals, and then the flotation selectivity of spodumene from gangue minerals became wores (Wang and Yu 2007; Yu et al. 2014). In order to eliminate the negative effects of slime and metal ions on the flotation of spoddumene, the desliming and long time scrubbing with the addition of NaOH and Na2CO3 were adopted. Usually, NaOH shows the activation for spodumene flotation, and the recovery of spodumene increases with the increase of NaOH dosage. Na2CO3 can eliminate the non selective activation of Ca2+, Fe3+, Mg2+ ions in the pulp, and the concentrate grade of spodumene increases with the increase of Na2CO3 dosage. Anionic collectors such as chelants, hydroxamic acid, oxidized paraffin soap, naphthenic acid and oleic acid were widely used for the flotation of spodumene (Dresler et al. 1998; Moon and Fuerstenau 2003; Menéndez et al. 2004; Yu et al. 2015)."

Jan 1, 2018

By Ye Chen, Jianhua Chen, Meng Liu, Yuqiong Li, Xiao Mu, Cuihua Zhao

"Sulfidization-amine is the most effective method for the recovery of smithsonite (ZnCO3), however the interface interaction details remain unclear. The sulfidization-amine flotation mechanism of smithsonite has been studied by Density Functional based Tight Binding (DFTB+) method in this paper. The slab model of ZnCO3 (101) surface was built and the adsorptions of a monolayer of HS- and S2- ions were conducted to model the sulfidization effect on the ZnCO3 (101) surface adsorption. DDA hardly interacts with the hydrated ZnCO3 (101) surface. Under the low concentration of Na2S, HS- ions form a Zn-SH-SH structure on the ZnCO3 (101) surface, which hinders the interaction between DDA and surface Zn atoms. Under the high concentration of Na2S, a layer of ZnS is formed on ZnCO3 (101) surface, which is favorable for the adsorption of DDA on the surface. This is consistent with the flotation practice where smithsonite flotation requires a large amount of sodium sulfide. The results could provide a microscopic investigation into the sulfidization-amine flotation mechanism of smithsonite.INTRODUCTIONSmithsonite (ZnCO3) is an important and typical oxide mineral of zinc. It is a semi-soluble salt mineral with a solubility product constant of 1.46 × 10-10 (Weast, 1973). The most common and effective method to recover oxidized zinc ores is froth flotation (Caproni et al., 1979; Pereia and Peres, 2005; Kashani and Rashchi, 2008). It is well known that the flotation of oxidized zinc minerals is much more difficult than the flotation of zinc sulphide minerals (Hosseini and Forssberg, 2007).The recovery of zinc oxide ores with poor floatability attracts more and more attention due to the depletion of easy-recovered of zinc sulfide ores.Sulfidization-amine flotation, which using Na2S as sufidizing agent and amine as collector (Mckenna et al., 1949; Rey, 1954; Abramov, 1961; Rey, 1979; Hosseini and Forssberg, 2007). This method is the most successful technology used for zinc oxide minerals flotation in large-scale industrial applications since it was invented in the 1950s (Önal et al., 2005; Pereira and Peres, 2005). There have been numerous experimental researches on the sulfidization-amine flotation of smithsonite. Shi et al., (2013) studied solution chemistry of smithsonite flotation system. Feng and Wen (2017) studied the formation of zinc sulfide species on smithsonite surfaces and its response to flotation performance. Wu et al., (2017) investigated the sulfidization behavior of smithsonite with the use of zeta potential, inductively coupled plasma (ICP), scanning electron microscope (SEM), and X-ray photoelectron spectroscopic (XPS). Their measurement results confirms the chemisorption of sulfur ions and the formation of ZnS film on the smithsonite surface after Na2S treatment, however the influence of HS- ions on the surface and the influence of sulfidization on the amine adsorption have not been discussed."

Jan 1, 2018

By Brian Loveday, Sandile Nkwanyana, Indresan Govender

"Recent batch experiments by the authors in a pilot scale ball mill (Ø = 0.6m) have demonstrated that a partial replacement of the ball charge by pebbles (25 % pebbles; 75 % steel balls) optimally reduces the ball and power consumption without altering the rate of production of fine material (passing 75 microns). At higher pebble volumes, the production rate of fines was reduced progressively. With the 25/75 composite charge a saving of 13 % in power consumption was achieved, and a saving of 25 % in steel ball consumption is implied. A partial replacement of steel balls by pebbles reduces the overall density of the grinding media in the charge. Taking into consideration that the production rate of fines is usually proportional to the bulk density of the charge in the mill, it would be expected that a composite charge (e.g. 25/75) would coarsen the grind and consequently reduce the rate of production of fines. Pebble wear contributes a small proportion of fines and it doesn’t provide a full explanation of why the 25/75 composite charge has no (or minimal) adverse effects on the rate of production of fines. Clearly, the production of fines across the mill is directly related to the shear and compressive power dissipation density. Accordingly, we hypothesise that the spatial power dissipation distribution meeting the minimum requirements for fines production— at the so-called active regions—are equivalent, or minimally comparable, for both the 25/75 composite and 100 % ball charge operating conditions. To test the hypothesis, we performed DEM simulations to analyse power dissipation in the active regions. 1. INTRODUCTION Comminution remains to be the most expensive process in mining operations, particularly because the energy consumed in this process accounts for 30-70 % of the total cost of a mining operation (Nadolski et al, 2014). Optimization of comminution circuits has been focussed on reducing capital and operating costs and maximising throughput capacity. For existing operations, it is often a challenge if the optimization process recommends retrofitting new ‘major’ equipment. The challenge arises from new capital cost and the difficulty of retrofitting in an existing circuit, while maintaining production (Major et al, 2001). Thus, for existing mining operations, optimization of comminution (cost and throughput) is often limited to operating conditions and/or addition of auxiliary equipment (such as pebble crushers, additional screens and high pressure grinding rolls (HPGR)) (McIvor and Greenwood, 1996; Hart et al, 2001; Powell et al, 2015b)."

Jan 1, 2018

By M. Gonzalez Fernandez

"If the final goal of metallurgy is the extraction of metals from a given ore, everyone knows that this achievement relies on many separation steps involving much more than a biphasic material made of metal and gangue. Nevertheless, still today, most of the design and follow-up of industrial processes only consider metal grades; in best case metal grades per size class. Working with such heterogeneous material, made of several minerals, with different grain size and texture, implies to consider finer ore models to be able to predict the behavior of material and the subsequent operation performances. Analytical tools are now available to provide such relevant and accurate data which are applied in geometallurgy. To achieve a true geometallurgical approach for process design, but also for optimization, accurate process simulation absolutely needs to combine these fine ore models with the corresponding unit operation models. Based on generic, but configurable, criteria of description and a hierarchical approach, the material modelling tool embedded in the USIM PAC process simulator provides the necessary flexibility to describe any type of ore with almost no limit in the level of details and associated physical properties that can be met in the mining industry. The simulation engine and the mathematical models of unit operations are designed to manage such a diversity of material modelling. The paper present various ore models and some of their applications in flowsheet simulation. It proves the interest of this detailed and advanced approach to accurately predict plant performances. INTRODUCTION Process simulation used for process design and optimization requires accurate unit operation modeling. During the last decades, main efforts of the different teams developing software simulators have been dedicated to those models for comminution and physical separations such as flotation or gravity concentration (Kojovic et al., 2012, Soni and Yoon, 2014). In most case, the ore is modelled with a size distribution and metal or mineral grades. A water phase is considered for wet processes. The association of unit operations and such material models generally allows, after some parameters adjustment, to achieve good agreement between experimental and simulated data. The use of the obtained simulator to test alternative configuration of circuits or settings of equipment devices can be accurate enough as far as the ore processed is close to the ore used for simulator adjustment. However, when the ore gets very different grades, coming from different mineral proportions or grain sizes, the simulation results can be of poor accuracy. Because any physical separations such as gravity, magnetic or flotation, do not sort metal and gangue but particles, made of minerals, containing metals, the only way to be accurate enough for allowing extrapolations, is to model particles. The phase model tools embedded in the USIM PAC process simulator gives this possibility. However, as such level of details are not always available for analyses, the tool has been designed with a high level of flexibility, to adapt the model to the available data. In this paper, the principles of this conceptual modelling tool are presented, and some application cases illustrate the material model flexibility and its interest."

Jan 1, 2018

By Teja Reddy, Narasimha Mangadoddy, Mandakini Padhi

"In mineral comminution circuits, the feed to hydrocyclone consists of a heterogeneous mixture having varied degrees of liberation and sizes leading to the multi-component particle system. The presence of multicomponent particles exhibits a significant change in the classification performance parameters. In this work, a numerical study is conducted with an artificial mixture of magnetite and silica of different proportions having similar particle size distribution to understand the multicomponent interaction in a laboratory scale hydrocyclone. The heterogeneous feed is injected tangentially would attain different settling rates under the influence of centrifugal, drag and turbulent dispersion forces. In this work, Large Eddy Simulation (LES) is used to resolve the continuous phase turbulence. Modified Algebraic Slip Mixture (ASM) model using the corrected Newtonian rheology of fines to simulate multi-density and multi-size particles of the mixture in a hydrocyclone. The influence of the multi-component particles on classification performance is extracted from the simulation in terms of the performance curve, i.e. recovery to underflow, volume fraction distribution and the key forces acting on each particle in the mixture. An interaction was observed between different components during the classification process, featuring accumulation of heavier particle at wall-side pushing the lighter particles into the inner locus of zero vertical velocity (LZVV) zone. The comparison of separation factors of different size particles presented the higher probability of the magnetite of same size reporting to wall region and hence to underflow. Hence, an increased component cut-size with the increased magnetite proportion, particularly a profound effect on lighter density component’s cut-size was observed. INTRODUCTION The multicomponent existence is found in naturally occurring ores, affecting the pure metal extraction, nonetheless also affects the comminution and classification processes. Among many another classifier, hydrocyclone is a vital equipment used vastly in many industries. The main advantages over other classifiers are a static body, low operating cost and maintenance, high throughput, low floor space requirement etc. A typical hydrocyclone consists of a cylindrical section with a central tube connected to a conical section with a discharge tube. The fluid is injected tangentially into hydrocyclone causes swirling and thus generates centrifugal force within the device. The multiphase interaction inside the hydrocyclone is extremely complex and mostly explained by theories based on hypothesis. In past years, many theoretical models were proposed like a balanced orbital model (Criner, 1950), the residence time model (Reitema, 1961) etc. Though these models give an estimation of the cut-size and other performance parameters, it cannot predict the accurate performance of the actual state of operation. Among these models, the balanced orbital theory is the most adapted concept, based on the force balances of the particle in the dual vortex flow of hydrocyclone. The finer particle is subjected to the inward drag force, generated from the outer vortex flow to the air core, and drags the particle towards the overflow. The larger particle with the higher mass have enhanced centrifugal force and falls into primary vortex near wall reporting to the underflow. Generally, the forces acting on the particle include the drag force, centrifugal force, pressure gradient force, added mass force, Saffman lift force, Magnus force and basset force (Kraipech, 2005). The major forces like a drag, centrifugal, pressure gradient are the function of the particle properties like the size and the density. Hence, the existence of the multi-size and the multi-density particle will affect the separation phenomenon, with the varied forces acting on it. The understanding of the multicomponent classification effect using ores has been only explored in few studi"

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 G. I. Voiloshnikov, V. E. Dementyev

"One of the most important advances in the world gold metallurgy is the introduction of adsorption technologies for processing of ores and concentrates. «Adsorbent-In-Pulp» process allows to eliminate pulp filtration that is especially important during processing of clay and slime bearing ores. “Adsorbent-In-Leach” process is one of the ways for processing of preg-robbing (carbonaceous) products. High efficiency, increased metals recovery, decrease in capital and operational costs, possibility of easy control and adjustment are the advantages of adsorption processes. Anion-exchange resins and activated carbons are used as adsorbents. This paper presents Irgiredmet experience on gold adsorption technology using both adsorbents (RIP, RIL, CIP, CIL processes). It includes results of long-term studies of different theoretical and practical issues of adsorption processes. Irgiredmet started development of ion exchange technology (RIP, RIL) in 1964. Laboratory and pilot plant tests were conducted to develop process design criteria for 15 RIP plants of the former USSR. During this test work a great number of newly synthesized resins including strong- and medium-base resins was studied, different types of adsorption feed (ores and concentrates) were tested; some theoretical regularities of adsorption process were investigated; the technology of two stage adsorption for silver gold ore, improved flowsheet for gold elution and resin regeneration, designs of technological equipment for adsorption, elution, electrowinning processes including pulsation columns, electrowinning cells etc. were developed. Irgiredmet took part in commissioning of practically all RIP plants in the former USSR. Due to its efforts RIP process became to be the standard technology. Last Irgiredmet RIP projects include the development of adsorption technology using medium-base resin for the three mines owned by GC Petropavlovsk (Amur region, Russia). The complex of the testworks on activated carbon gold adsorption technology including the search of prospective activated carbons; study on gold adsorption mechanism; development, testing and introduction of process flowsheets and the equipment for their realization was conducted. The original gold elution process was developed. The developed CIP technology was firstly introduced at Lebedinsky gold plant (Yakutia). Now carbon adsorption technology is widely used at Russian gold mines as CIP, CIL, CIC processes. The most relevant example of CIP introduction is Svetlinsky gold plant (Ural, Russia) with capacity 8 Mt of ore/ year."

Jan 1, 2018

By Richard Mills

Autonomous Underwater Vehicles (AUVs) are proven technologies used across market segments for survey, exploration and environmental monitoring tasks. When coupled with other autonomous platforms or sensor packages AUVs become part of an holistic system approach to exploration and environmental assessment and monitoring. Recent developments have seen AUVs deployed remotely with instantaneous access to data via the cloud. Our goal is to deliver the capabilities of each of these elements and present a cohesive data set with automated processing tools over a cloud based interface. nmanned Technology AUVs The HUGIN AUV System is the most commercially successful AUV ever built. Operated as a single vehicle, or as part of a swarm, HUGIN’s area coverage rate is unrivalled. Equipped with a comprehensive sensor package including Kongsberg’s synthetic aperture sonar, it collects a data set. Some of these data are processed in-mission to enable operators to readily access it when the vehicle is recovered. HUGIN is well suited to mining survey and exploration. Capable of reaching 6000 metre depths and conducting missions greater than 60 hours, HUGIN collects seabed sonar imagery, sub-bottom profiles, laser and camera images plus environmental data, with sensors running concurrently.

Jan 1, 2018