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By R. Kaibyshev, I. Zuiko

"The effect of thermomechanical processing (TMP) including cold working by tension or rolling before aging on mechanical properties and a dispersion of secondary phase particles of an AA2519 alloy (Al–5.64Cu–0.33Mn–0.23Mg–0.15Zr–0.11Ti–0.09V–0.08Fe–0.01Si (wt. %)) was examined. It was shown that the use of tension to impart pre-strain =10% in the alloy provides the best combination of properties in peak aging condition of the material. The AA2519T87 alloy processed by tension exhibits the yield stress, ultimate tensile strength and elongation to failure of 425.4±2.4, 475±2.4, 12.1±0.4, respectively. The one pass rolling leads to -5% decreases in yield stress and –20% decreases in ductility. Dislocations serve as heterogeneous nucleation sites for ?'-phase precipitation. The positive effect of tension is attributed to the formation of more homogeneous dislocation structure, uniform distribution of ?'-phase particles with higher aspect ratio. Precipitation of the O–phase plates on {111}a habit plane was detected. In addition it was shown that the low angle boundaries are heterogeneous nucleation sites for ?' and O particles.INTRODUCTION Precipitation-hardened alloys are a commercially important group of the materials because their mechanical properties can be modified by treating and changing the microstructure. Age-hardenable aluminum alloys belonging to the Al–Cu–Mg system are widely used due to their attractive combination of high specific strength, good fracture toughness and enhanced creep resistance attributed to the highly efficient strengthening by the ?'-phase (Palmer, StJohn, Nie, & Qian, 2017). An AA2519 alloy exhibiting superior mechanical properties among high-strength Al–Cu alloys (2XXX-serie) due to minor Mg additives. It is known that, in alloys with high Cu/Mg ratio (=5.6) the classic precipitation sequence (Palmer et al., 2017; Wang & Starink, 2005; Wang et al., 2010) of supersaturated solid solution (SSSS) decomposition occurs: SSSS ? GP zones (Al3Cu) ? ?? (Al3Cu) ? ?' (Al2Cu) ? ? (Al2Cu) (1)"

Jan 1, 2018

By Regis Texeira, Leopoldo Gutierrez, Vicente Hernandez, Caludia Vidal, Lina Uribe

"Molybdenum is currently the most important by-product of Chile´s copper mining industry. This mineral has gained international relevance over the years, because of its price. At mining deposits in Chile, copper and molybdenum are extracted together and then separated in a concentration process consisting of several flotation steps using sodium hydrosulfide (NaHS) as copper depressant. However, there are environmental issues related to the potential emisions of toxic hydrosulfide gas and bad odours, which affects nearby communities and suppose a risk for operators. This problem has led to the need for development of new technologies to eliminate the use of NaHS in the process of selective flotation of Cu and Mo minerals. In this work, results of flotation tests in which lignin derivatives reagents are used to obtain the selective separation of Cu and Mo minerals by flotation are presented. In this technology molybdenite is depressed by the action of lignin derivatives (lignosulfonates), while copper sulfides remain hydrophobic and float. The use of lignin derivatives in the selective flotation of copper molybdenum minerals represents a non-toxic alternative to NaHS.INTRODUCTIONSeparation of copper sulfides from molybdenite is commonly achieved through a two-stage flotation process. In the first stage the collective flotation of copper sulfides and molybdenite is promoted to generate a collective concentrate which is then treated in a second stage with sodium hydrosulfide (2.5-3.0 kg/t NaSH) to depress copper sulfides flotation without affecting the flotation of molybdenite. As a result a copper concentrate with 30-35% Cu, and a molybdenum concentrate with 50-52% Mo are generated. Although this process is widely used at industrial level, environmental issues related to the risk of H2S generation and bad odors have always been a concern. Thus there is a need in the industry for a more environmentally friendly process to separate copper sulfides and molybdenite."

Jan 1, 2018

By Xiaoxu Sun, Jianchao Yao, Jiancheng He, Shijie Lu, Hongxi Zhou

"The ball mill performance relies on impact grinding, but it has disadvantage of the lower efficiency when the ore is finer; while tower mill relies on friction shear affection with high energy efficiency, which is considered to be one of the most potential fine grinding equipment all over the world. Generated by the agitator device, the internal media movement is complex because of comprehensive interaction of screw mechanism, cylinder structure and adjacent media, which is the key factor of grinding process. But the kinematics parameter ,such as speed, acceleration, stress and so on, of media motion cannot be obtained through traditional laboratory test method, which restricts deeply research on finer grinding mechanism seriously. In order to solve this problem, characteristics of media motion in tower mill is studied via the discrete element method. Coefficient of restitution, coefficient of static friction and coefficient of rolling friction are the key parameters affecting the media movement, which were calibrated by stacking angle test firstly. A 3kW tower mill is established as the model for simulation. At last one appropriate simulation strategy is selected to increase simulation accuracy. The characteristic of media motion is obtained based on the computer simulation analysis: macroscopically, the media in tower mill is a dynamic equilibrium state generally accompanied by spiral up and down movement all the time. And it has been found that the maximum lifting height is proportional to the rotation speed of agitator shaft. The velocity of media at the edge of screw stirrer is biggest, while the velocity of media near the cylinder wall is smaller, so the grinding performance between the two ring areas is the best. The rotational speed of agitator shaft and media filling ratio are the two most important operating parameters in tower mill. The impact curve of two main operating parameters on the grinding intensity and energy efficiency are obtained. All these can provide theoretical basis and technical support for operating parameters setting of industrial tower mill."

Jan 1, 2018

By V. G. Minenko, V. A. Chanturiya, A. L. Samusev

Eudialyte is one of perspective resources of zirconium and other rare earth elements (REEs). Large reserves of eudialyte concentrated in the Murmansk region of the Russian Federation. Usually, technologies of REE treatment include the decomposition of eudialyte concentrate in different acidic, extraction and utilization of all components. The main problems in the leaching of eudialyte include are: the formation of an unfiltered silicon-containing gel; low recovery of REE; difficulty extraction of metals from the productive solution; high aggressiveness of the reagents. One of the promising trends of intensification of the processing of hard-to-degrease rare metal raw materials is the use of energy methods for affecting mineral suspensions. These methods make it possible to increase the efficiency of break up fine-dispersed mineral complexes and extracting micro- and nanoparticles of a valuable component in subsequent deep processing. The purpose of this work is to investigate the effect of energy impacts on the nitric acid leaching of eudialyte concentrate. Experimental studies were carried out in a developed laboratory facility that makes it possible to evaluate the effect of electrochemical, ultrasonic and combined effects on the leaching of zirconium and REE from eudialyte concentrate. The studies carried out on the samples of eudialyte concentrate with the size class of -0.315 + 0.063 mm showed that the use of electrochemical and acoustic effects increases the extraction of ZrO2 in the production solution in 1.6 - 2.5 times, REE in 1.3 - 2.2 times, respectively. An analysis of the microstructure and phase composition of the surface of the eudialyte concentrate showed that the intensification of the leaching process is due to surface cleaning from the silicon-containing gel, as well as the opening of capillary channels and microcracks, which accelerates mass-transfer processes. The results obtained open wide opportunities for creation of modern and effective technology of processing of eudialyte concentrate, producing high-quality zirconium products and REE.

Jan 1, 2018

By K. C. Corin, M. S. Manono, J. G. Wiese

"It has been suggested that hydroxo species, particularly those of calcium, selectively adsorb onto gangue minerals. Such species enhance the depressive action of carboxymethyl cellulose (CMC) onto gangue via an acid-base interaction between the positively charged mineral surface and the negatively charged CMC molecule. Thus, the hydrophilicity of gangue minerals is enhanced, preventing the dilution of the concentrate. However, as there is little evidence to support these claims it is important to investigate. Adsorption data and mineral surface charge analyses will allow a fundamental understanding into how electrolytes and their ionic strengths affect gangue-depressant adsorption. It is strongly anticipated that decoupling these effects will allow process operators to tailor their process water quality needs towards best flotation operating regimes and in the long run effect closed water circuits. Thus, using talc and pyrrhotite as proxies, this work investigates the influence of the ionic strength of process water on the adsorption of CMC onto minerals in sulphide flotation.INTRODUCTIONThe phenomenon of gangue depression in mineral flotation is of critical importance as regards the attainment of a required concentrate grade. This thus suggests that the depressant of choice has to have a highly selective affinity for the targeted gangue minerals. This would ensure the necessary prevention of gangue from reporting to the concentrate without inadvertently depressing the value bearing mineral. The chemistry of the environment regulates the manner in which gangue depression occurs. In sulphide flotation, polysaccharides are used as depressants of choice to depress naturally floatable gangue which may in the case of Merensky ores exist as talc. The two widely used polysaccharides in the South African context are carboxymethyl cellulose (CMC) and modified guar gum. It is suggested that polysaccharides depress gangue by rendering the surface of gangue hydrophilic or by preventing the formation of hydrophobic layers on gangue mineral surface, forming large gangue aggregates and thereby increasing their heterocoagulative nature (Shortridge et al., 1999)."

Jan 1, 2018

By Zhaohui Wang, Jiachen Wang

"Effective surrounding rock control is a prerequisite for realizing safe mining in underground longwall faces. In the past three decades, longwall top-coal caving mining (LTCC) and single pass large height longwall mining (SPLL) found expanded usage in extracting thick coal seams in China. The two mining methods lead to large void space left behind the working face, which increase the difficulty of ground control. Longwall face failure is a common problem in underground mining, which is induced due to low strength and high fracture density of the coal seam. Moreover, the stiffness of main components included in the surrounding rock system also greatly influences longwall face instability. Correspondingly, the surrounding rock system is developed for LTCC and SPLL faces in this paper. Mechanical conditions for simultaneous balance of roof structure and longwall face are put forward by taking the stiffness of coal seam, roof strata, and hydraulic support into account. The safety factor of the longwall face is defined as the ratio between its ultimate bearing capacity and the load imposed on it. The influence of coal strength, stiffness of the coal seam, roof strata, and hydraulic support, as well as the movement of roof structure, are analyzed. Finally, the key elements dominating longwall face stability are identified for improving surrounding rock control effectiveness in LTCC and SPLL faces.INTRODUCTIONThe concentration of coal mining in China is gradually shifting to the west region, and there are a large number of thick coal seams in the newly formed coal mining area. Therefore, the surrounding rock control problems related to mining of thick coal seams will become the focus of research in the field of mining engineering in the future. There are two kinds of mining methods for thick coal seams in China, including single pass large height longwall mining (SPLL) and longwall top-coal caving mining (LTCC). Both methods can accomplish the goal of excavating the full thickness of thick coal seams at one time. SPLL mining benefits from the improvement of the development level of associated equipment. The appearance of large hydraulic supports and high power shearers ensure that the height protected by the hydraulic supports and the height of the sheared coal are the same as the coal thickness. LTCC mining benefits from mining technology advantages. The thick coal seam is divided into two sub-layers, and the working face is normally installed in the bottom layer, while the top coal is caved under the compressive forces due to mining. Therefore, there is a scraper conveyor at the front of the hydraulic support for transporting the sheared coal and another one at the tail for transporting caved top coal. Both SPLL and LTCC methods realize one-off recovery of thick coal seams."

Jan 1, 2018

By Vladimir F. Skorokhodov, Nikolay N. Melnikov, Svetlana P. Mesyats

"Among the problems of the civilization development, a problem of interaction between man and natural environment can be highlighted. In the twentieth century the human transforming activity had got scales of geological processes and defined the contradiction between the goal to increase the quality of human life and possibilities of the natural environment. Last twenty-five years after the World Summit on the Environment (1992) indicate that the development of civilization is still based on receiving super profits from the natural resources exploitation. This statement is confirmed by economy globalization rates, growing contradictions between consumption and production, depletion and degradation natural environment. A new technological order is formed at the time of growing world population, technological capacities, organizational complexity, from one side, and global scales of geo-resources consumption, on the other side. Sciences, determining the further civilization development, should take on the task to change the social worldview, since the preservation of human population consists in remediating and maintenance of biosphere functions as a regulator of ecological balance. The new worldview in the geo-resources exploitation is based on the Ecological strategy of mining development, which consists in reducing mining-induced loading on natural environment while increasing efficient mineral production and processing, and providing for a comprehensive solution of tasks on mineral deposit development. One of strategic trend of mining development is to increase complexity and completeness of useful component extraction from ore and mining deposits while reducing wastes and decreasing their stockpiled volumes. The implementation of the ecological strategy has shown that the future is determined by reduction of the environmental impact while improving the efficiency of mineral mining and processing.INTRODUCTION The global nature of environmental problems caused by the scale of consumption of natural resources, huge amounts of waste, and intensive man-made impact on the environment requires a revision of the strategy for the natural resources development. Many existing technologies are ineffective in achieving the ultimate goal. Direct output in the raw materials - the end product technological chain rarely exceeds 10%, which implies a huge amount of work to move the soil. In addition, the feature of scientific and technological progress at the present stage is the growth of power-to-weight ratio."

Jan 1, 2018

By J-S. Marois, F. Cappucitti, Y. Dodier, D. Downey, G. Matton

"The flotation processes of the Niobec Mine have been affected by a seasonal loss of recovery and a significant increase in reagent consumption over the past few winters. This paper discusses the problem-solving methodology that was used to identify the root causes, to develop solutions and to implement changes that resolved the problem to restore the process to summer-like conditions year-round. Mainly, it was found that the process water was contaminated by phosphates ions, which adversely affected the carbonate pre-flotation, and caused detrimental effects on the subsequent niobium flotation. The phosphate ions were being generated by the process itself, but were consumed by algae in summer conditions. It was determined in laboratory studies that concentrations as low as 5 ppm were enough to affect the circuit and that the multiple additions of process water throughout the circuit was worsening the effect. Also, temperature was found to have an impact on the reagent performance. The performance of the plant was restored by implementing a natural treatment of our process water with a simple cost-free rearrangement of our circuit streams. In addition to that, our extensive geometallurgical program was used to provide ore to the plant restricting phosphate generation in the process. Also, a modification of the collector was developed and introduced in the carbonate pre-flotation that provided improved performance during the periods of low pulp temperature.INTRODUCTION Niobec is one the three major global producers of niobium presently in operation. Situated in the Saguenay-Lac-St-Jean region of Quebec and in operation since 1976, the site produces ferroniobium (FeNb) to be used mainly in High Strength Low Alloy (HSLA) steel, which is known to have better mechanical properties than carbon steel. The Niobec operation consists of an underground mine, a concentrator and a converter plant. The concentrator concentrates niobium-bearing minerals, mainly pyrochlore and columbite, to produce a high-content Nb2O5 concentrate which is then converted to FeNb in the converter plant by an aluminothermic reaction. The Niobec concentrator flowsheet, which has gone through many expansions and optimisation over the years, consists of grinding, desliming, flotation and leaching steps. The flotation steps are numerous, sensitive and difficult to operate due to the non-selective nature of oxide mineral collectors. Thus, the pyrochlore concentration process at Niobec still faces many challenges and is constantly going through periods of continuous improvement."

Jan 1, 2018

By S. G. Luckey, N. R. Harrison, F. Nadeau, U. Brüx

"The adoption of tailored-rolled or tailor-welded blanks (i.e. TRB/TWB) in the automotive industry has been known to offer great potential for the optimization of weight, function, cost and complexity. Vehicle light weighting can further be achieved by using high strength aluminum alloys like the 7xxx-series. 7xxx-series alloys are capable of delivering specific strengths equal to or greater than high strength steels. However, room temperature formability of this aluminum class is limited, so one approach to forming 7xxx-series alloys is by hot stamping. Hot stamping utilizes an elevated temperature blank and the high pressure stamping contact of the forming die to simultaneously quench and form the sheet. This paper explores the initial feasibility of tailored thickness material for body-in-white applications when processed under hot stamping conditions.INTRODUCTION Steel tailor-rolled blanks (TRB) or tailor-welded blanks (TWB) have been used within the automotive industry as a method of reducing weight, expanding material utilization, and decreasing overall part/assembly cost (Ganeasan et al., 2015; Merklein et al., 2014; Hirt et al., 2005; Kridli et al., 2000). The production of such tailored thickness materials has resulted in over $2.5 billion (2016) in combined industry sales (Mubea, 2018). As automakers begin to adopt the manufacturing practices traditionally reserved for steel such as tailor rolling/welding with greater enthusiasm for vehicle light weighting, there exist an opportunity to expand the material database to extend beyond the traditional aluminum alloys found in current production. High strength aluminum alloys, i.e. 7xxx-series, are ideal for structural automotive applications due to their high specific strength; however, they have limited room temperature formability. Hot stamping, another manufacturing practice used by the steel industry, can be used to form these high strength materials. The combination of tailoring the thickness of a sheet material and hot stamping provides an opportunity for significant weight saving within an existing manufacturing footprint. This paper explores the potential and challenges of this approach when applied to structural body-in-white components. The methods for tailor rolling, tailor welding and hot stamping are described and applied to the production of a 7075 aluminum alloy B-pillar. The results are discussed in terms of feasibility and weight savings."

Jan 1, 2018

By Hidenori Hatta, Takero Watanabe, Hideo Yoshida

"The effect of the quenching rate on age hardening in an Al-6.0mass%Zn-0.75mass%Mg alloy sheet was investigated. The quenching rates and aging conditions were as follows: water quenching (WQ) or furnace cooling (FC) followed by pre-aging at 20°C,then artificial aging at 120, 160 or 200°Cwere performed. The peak strength of the FC and the WQ are very similarat120°C aging. It is important high strength was obtained even at the extremely slow quenching rate. On the other hand, the strength of the WQ significantly decreased compared to the FCat200°C aging. GP(I) zones were formed during the pre-aging at 20°C even if the cooling rate was very slow like the FC, and were transformed into the GP(II) ones at 70°C or higher and then into the ?’ phase. However, these zones were dissolved by reversion during heating to 200°C. Thus the strength of the WQ decreased. On the other hand, it is considered that an unknown cluster or GP zone with a thermal stability formed during the FC was not dissolved up to 200°C and was transformed into the ?’ phase. Therefore, a higher strength was obtained in the FC for the200°Caging.INTRODUCTIONAl-Zn-Mg alloys are widely available in commercial production because these alloy have lower quench sensitivity and can be produced by air cooling (AC). Heat treatable aluminum alloys are usually produced by water quenching (WQ) to increase their strength because a high cooling rate inhibits the precipitation of the stable phase during cooling and increases supersaturated solute atoms. However, Baba(1967)reported the strength of an Al-6%Zn-1.8%Mg(mass%) alloy without additional elements quenched by very slow cooling (15°C/min) was 96% of that quenched by WQ. Furthermore,the age hardening at room temperature (RT) occurs after annealing at 410°C followed by furnace cooling (FC, 0.5ºC/min or less)in these alloys. Therefore, the process of annealing at 410 to 430°C for 120 min followed by AC, and reheating at 230°C for 240 min, then cooling is recommended in the specifications (Japan Aluminum Association, 2011). Matsuda and Yoshida(1996)also recommended annealing at 300°C for Al-Zn-Mg alloy extruded products to inhibit age hardening at RT by precipitating the solute atoms and decreasing them in the matrix. It has been considered that the higher the content of excess quenched-in vacancy becomes by WQ, the higher aging rate at RT is obtained. Therefore,it is theoretically and commercially important to clarify the reason why the age hardening occurs relatively quickly in almost no excess quenched-in vacancies such as the FC, and why the same strength as the WQ can be obtained in the FC"

Jan 1, 2018

By T. Grounds, K. Singh, W. R. Reed, R. Cross, G. Ross, S. Klima, M. Shahan

"A 2nd generation roof bolter canopy air curtain (CAC) design was tested by National Institute for Occupational Safety and Health (NIOSH) at a Midwestern underground coal mine. During the study, the roof bolter never operated downwind of the continuous miner. Using a combination of personal Data Rams (pDR) and gravimetric samplers, the dust control efficiency of the roof bolter CAC was ascertained. Performance evaluation was determined using three methods: (1) comparing roof bolter operator concentrations underneath the CAC to roof bolter concentrations outside the CAC, (2) comparing roof bolter operator concentrations underneath the CAC to the concentrations at the rear of the bolter, and finally, (3) using the gravimetric data directly underneath the CAC to correct roof bolter operator concentrations underneath the CAC and comparing them to the concentrations at the rear of the bolter. Method 1 dust control efficiencies ranged from -53.9% to 60.4%. Method 2 efficiencies ranged from -150.5% to 52.2%, and Method 3 efficiencies ranged from 40.7% to 91%. Reasons for negative and low dust control efficiencies are provided in this paper and include: incorrect sampling locations, large distance between CAC and operator, and contamination of intake air from line curtain. Low dust concentrations encountered during the testing made it difficult to discern whether differences in concentrations were due to the CAC or due to variances inherent in experimental dust measurement. However, the analyses, especially the Method 3 analysis, show that the CAC can be an effective dust control device. INTRODUCTION Canopy air curtains (CAC) have been shown to be an effective respirable coal mine dust control for roof bolters in a laboratory setting with dust control efficiencies ranging from 14% up to 75% [Goodman and Organiscak 2001, Listak and Beck 2012, Reed et al. 2017]. Unfortunately, there is limited information on their effectiveness for controlling respirable coal mine dust in the field. On continuous miners, CAC dust control efficiencies ranged from 23% to 69% [Krisko 1975]. Two underground tests of the CAC on roof bolters demonstrated dust control efficiencies of 35% and 53% [Listak and Beck 2012] before problems occurred with operation of the CAC. Since the implementation of the new respirable coal mine dust limit from 2.0 mg/m3 to 1.5 mg/m3 (Code of Federal Regulations, 30 CFR 70.100, 2015), roof bolter CACs are becoming more commonplace in underground coal mines as a dust control tool to prevent roof bolter operator overexposure to respirable coal mine dust. J.H. Fletcher & Co. has been instrumental in delivering an effective design which incorporates the filter, blower, and canopy plenum seamlessly into the design of the roof bolter, resulting in a successful operational roof bolter CAC."

Jan 1, 2018

By Francis Breton, Daniel Larouche, Pierre Heugue, Rémi Martinez

"Nowadays, in order to fit environmental restrictions, automotive markets are demanding cast aluminum alloys working at high temperature (180–300°C). New generations of alloys are required for higher strength components in engine downsizing or start-stop systems which lead to higher loading and higher specific power and stretch current materials to their limits. Recently, transition metals, such as zirconium and vanadium, have been added as alloying elements into an AlSi7Cu3.5Mg0.1 alloy to improve physical, mechanical, thermodynamic properties with the aim of increasing service life of parts. In such alloys, the best mechanical properties are associated with the formation of precipitates through an optimum heat treatment sequence, including: solutionizing, quenching and artificial aging. This study is focused on the modified AlSi7Cu3.5Mg0.1 cast alloy with Mn, Zr and V additions for high temperature application. The characterization of the cast alloy in this study, firstly, helps to evaluate and understand its performance both chemically and structurally according to their physical state: as-cast or as-quenched. Comparison of precipitation kinetics between a binary Al-3.5%wt.Cu alloy and the AlSi7Cu3.5Mg0.1 (Mn, Zr, V) alloy has been characterized by differential scanning calorimetry, TEM observations and micro-hardness testing. The Kissinger analysis was applied to extract activation energies from non-isothermal DSC runs conducted at different stationary heating rates. The study focuses on the impact of the chemical composition such as Si content on the kinetics parameters.INTRODUCTION Pure metal Aluminum shows poor mechanical properties and its malleability is high, that is why alloying elements are added to the mixture before casting to improve physical, mechanical and thermodynamic properties (Javidani, 2015); such as Silicon (Si) for casting properties (castability, cold crack capability, wear resistance, shrinkage behavior), Magnesium (Mg) and Copper (Cu) to generate precipitation hardening systems. Aluminum hypoeutectic alloys (<12% Silicon) with Cu, Mg additions used in the automotive industry for manufacturing mechanical parts (Larouche & Javidani, 2014) are mostly subject, after casting, to precipitation hardening heat treatment (Mohamed & Samuel, 2012) according to specifications and associated standards. The best mechanical properties are associated with the formation of precipitates through an optimum heat treatment sequence, generally including: solutionizing, water quenching and artificial aging (Manente & Timelli, 2011). Hypoeutectic aluminum-copper alloy with amount of Cu around 1 to 4.5wt% is an elementary case for precipitation in heat treatable aluminum alloys. Researchers essentially focused their work on the full precipitation sequence of binary Al-Cu alloy during aging which is presented below."

Jan 1, 2018

By M. Javier

"Mining makes civilization possible. It also creates socio-economic problems surrounded by sustainability controversies yet continues extraction without considering the balance and finitude of nature. Nature requires restoration of equilibrium if mining and life on earth are to continue. Mining is still practiced according to Agricola’s views and the consequences it has wrought on our planet demand we critically reexamine it from its very core, to its metrics, to its design, to its technology, to how it is taught, and to reconsider its raison d'être in 2017. This paper offers tools to new mining engineers that are required to transform and solve new challenges. The task before us is to formulate an updated core curriculum that meets the demands and realities of the 21st Century. Mining professionals must rethink and reteach how to redesign mines before shovel hits dirt, how to mine with restoration of nature figured in to the mining design. Mining needs a new extractive technology in order to transform the results of its well-known liabilities. Mining has evolved and its future must be different than its past. Our industry is capable of doing this but it needs to be shown the way. INTRODUCTION The statement that ‘mining makes civilization possible’ is of the utmost importance and has the most value to us. We can examine the past and present appropriately to see the future that we are building. Mining must be addressed in a different way that makes a positive difference and improves upon rather than continues to get the negative impacts of the past. See Fig 1. Mining creates disequilibrium in Nature by producing ore, waste, tailing, dilution of resources, toxic, and pollution to its ecosystems. What is next for mining on a limited planet? Delaying the transformation of mining is not an option to developing an updated and modern mining business-as-usual paradigm. It is hurting the essentials of living in a civilization; our livelihood is in danger to the point of unrest in nature as we generate a lot of eco-print by present mining practices. So, we are urged to eliminate this bottleneck in life by employing a different design. This way, we will have a vision on how to sustain our civilization. [1]. This new design, with input from current and future generations, will be our contribution to posterity."

Jan 1, 2018

By S. Bozorgi, K. Anders

"The automotive applications of heat treatable AlCu cast alloys are designed for performance at high temperature, which can be improved using specially alloying element as well as different heat treatment. In this research work an effect of alloying element such as Cu, Ni and heat treatment on microstructures and mechanical properties of AlCu alloy were investigated using optical microscope (LIMI), scanning electronic microscope (SEM) equipped with energy dispersive X-ray detection (EDS), Differential scanning calorimetry (DSC) and mechanical testing. It was found that during solidification most of the elements Cu, Mg and Ni segregated at the grain boundaries in the form of Al2CuMg or Al7Cu4Ni and a very small part of Cu and Ni element dissolved in the FCC-Al matrix. The latter is not completely reclaimable for strengthening mechanisms in FCC-Al matrix in its as-cast state. The results of mechanical test show that yield strength and ultimate tensile strength increases after heat treatment significantly compared with the as-cast state. Furthermore the mechanical properties at elevates temperature (240°C) is higher with higher Cu+Ni+Si containing alloys compared with the less Cu+Ni+Si containing alloy.INTRODUCTION Due to the high strength-to-weight ratio, high strength and ductility at room- and elevated temperature, AlCuSi cast alloys are widely applied in the automotive industries specially for producing cylinder head and engine block, where modified alloys with enhanced metallurgical properties are always needed to satisfy the ever increasing demands for the applications. The AlCu based cast alloys can be strengthened by age hardening. The precipitation processes from which this hardening is derived can be attributed to the presence of selected trace element additions or micro alloying, which can change the process or kinetics of precipitation in age hardenable AlCu cast alloys (Polmear, 1998; Morris, 1991). Furthermore their strength is mainly controlled by the aging process through the precipitation and growth of very fine precipitates of the ?'-phase (a semi-coherent, metastable form of the equilibrium Al2Cu phase) from the Al and Cu Guinier-Preston (GP) zones. Several studies have shown that solute clustering occurs prior to the precipitation of GP zones, and this modifies both the nature and kinetics of the precipitation process. The typical size of GP zones is in the order of tens of nanometers, and the chemical composition of these precipitates is not easily measured, even with a typically analytical electron microscope (Polmear, 1989)."

Jan 1, 2018

By F. v. d. Meer, G. Kretschmar, T. Mütze, T. Leißner

"Dynamic air classifiers separate particles in a gas flow due to different particle trajectories utilizing differences in the settling velocity of particles as characteristic property for separation. The present contribution takes a close look at the separation of heterogeneous mixtures, in which valuables and gangue minerals show significant differences in density. The focus was on a moist iron ore sample, which was characterized in terms of mineralogy, grain size distribution, and particle size distribution. The material was classified at a cut size of 45 µm and at feed moistures between 0 and 6 wt.-%. Additionally to standard characterization techniques, the moisture of both products was measured as well as the yield of fines as product fraction in a corresponding processing plant. In addition, an automated mineral liberation analysis (MLA) provided information of the enrichment and segregation of individual mineral phases in the products. The MLA of the classification products reveals a selective comminution of the mineral phases and especially on overmilling of the valuables. For the first time, the separation of individual mineral phases has been assessed and compared to the classic assessment of classification processes by means of particle size analyses. KEYWORDS Dynamic classifier, segregation, MLA, selective comminution INTRODUCTION Dynamic air classifiers separate particles in a gas flow due to the different trajectories of the particles. The result of such a separation process depends on the gas throughput of the classifier, the dimensions, design and rotational speed of the deflector wheel, as well as the state of dispersion and thus the geometry of as well as the turbulence and interparticle interactions in the separation zone. Air classification of moist feed materials can be divided into several sub-process (Leschonski, 1977; Mütze et al., 2016): - dosage of the feed material, - dispersing the solid feed material into a gas stream, - feeding the dispersed material into the classification zone by pneumatic conveying, - drying of moist particles during pneumatic conveying, - separation of coarse and fine particles, and - separation of fine particles from gas."

Jan 1, 2018

By V. A. Ignatkina, V. A. Bocharov, T. I. Yushina, I. M. Petrov, A. A. Kayumov

"The purpose of this research was aimed at increasing recovery of metals from rebellious sulfide polymetallic ores of nonferrous and rare metal deposits. The ores under consideration have common processing features, including textural and structural complex characteristics, irregularity of impregnation and wide range of grain size, up to nanoparticle size, variable complex mineral composition, low content of precious metals etc. This all predetermines the need for advanced processing schemes with deep selective liberation and separation of minerals with intercycle release into rough concentrate and fractional products with the use of multi-stage cycles of individual dressing, based on an optimum combination of various integrated beneficiation and hydrometallurgical processes. The application of existing standard processes does not enable the production of high-grade selective concentrates without reducing the recovery rate due to incomplete separation of fine mineral intergrowths and overgrinding of brittle ore and rock minerals.The combined beneficiation processes for such type of resources, aimed at increasing recovery of nonferrous, rare, and precious metals are based on flotation methods in combination with gravity concentration to produce rich rough collective or selective concentrates, comprising readily floatable mineral fractions. At the same time, hardly recoverable and non-separable mineral associations are released into separate concentrated products for following dressing by individual processes. The proposed combined process provides for successive selective liberation of minerals with release of rich readily recoverable mineral fractions at the preparation and ore beneficiation stages. The hardly recoverable mineral associations shall be released in subsequent operations with the use of dressing, based on a combination of beneficiation and pyro- and hydrometallurgical methods."

Jan 1, 2018

By V. V. Lvov, L. S. Chitalov

"The purpose of the research is intensification of physico-mechanical ore properties determination for ball grinding processes in comminution circuits. The research presents comparative studies aimed at intensification of Bond Ball Mill Work Index (BWi) determination, such as testing technique of Ahmadi and Shahsavari, Berry and Bruse, Gharehgheshlagh, Horst and Bassarear, Kapur, Magdalinovich. The subject of the research is a test procedure of apatite-nepheline, copper-nickel, gold-sulfide and iron ores for the Bond ball mill index. The Bond Ball Mill Work Index for the material firstly was determined by standard Bond test methodology. Two the most promising testing techniques - Ahmadi and Kapur testing techniques - were modified. For the Ahmadi technique it was proposed to pay attention to the circulating load, which should be stabilized on the value of 250% as fast as possible. Two methods were put forward to quicker stabilize the circulating load. For the Kapur technique it was proposed to use empirical coefficients, which is determined especially for the apatite-nepheline, copper-nickel, gold-sulfide and ores. The modified Ahmadi and Kapur techniques require no more than two cycles of ball grinding to determine BWi (while normally 6-8 cycles are required) and less than 5 kg of initial feed. The suggested modified Ahmadi and Kapur techniques allow to intensify the physico-mechanical ore properties determination for ball grinding processes and BWi test costs considerably, which makes them useful for mass sampling and monitoring strength properties of ores entering a concentrating mill. INTRODUCTION When designing concentrating mills, the choice of the technological scheme for ore pretreatment, particularly the type, quantity and size of the main process environment, the determination of optimal grinding conditions and the calculation of equipment load are carried out by preliminary studies of grinding in semi-industrial or laboratory-scale plants. Semi-industrial tests on full-scale plants provide the most reliable information for calculating specific loads for equipment. However, this requires a significant amount of ore samples, a high labor costs and the pilot plants. Thence the most researchers performed grinding tests with small laboratory equipment using small ore samples."

Jan 1, 2018

By A. S. Broesder

"With depletion of global ore deposits, there has been an increasing industry trend towards mining of lower average grade deposits in order to meet global demand, resulting in increased processing cost, energy usage and water usage. Consequently the industry is seeking pre-concentration technologies to reduce costs, increase production in existing operations and potentially enable the economic mining of previously uneconomical deposits. This pre-concentration can also advantage downstream processing and metal recovery. CSIRO has developed a large scale magnetic resonance based technology for the rapid quantitative detection of selected copper, iron and arsenic minerals in bulk ore. The technology is suited to measurement on large primary conveyors for enabling “pod” based sorting. The approach used in high tonnage sorting is to not sense and divert individual rocks, but to instead measure groups of rocks (“pods”) carried continuously on a single primary conveyor that can be diverted by conventional mechanical means. Bulk ore sorting operates by removing barren ore pods from a stream of crushed ore based on a bulk sensor measurement at a pod resolution of ~1 – 10 tonnes. The sorting process is based on the intrinsic variability of grade during the mining process that often occurs at the few tonne scale, and for instance, is common in many porphyry copper deposits. The MR technology has been proven in the laboratory for a wide range of copper, arsenic and iron minerals. A full scale prototype sensing system has been demonstrated in a trial at an Australian copper mine. Implementation trials of commercial MR based bulk sorting systems are progressing during 2018.INTRODUCTION An increasing trend in the mining industry is the exploitation of larger lower-grade deposits to meet global demand. Low-grade deposits involve increased processing cost, energy and water usage and increased tailings. There is therefore growing interest in technologies that enable more efficient extraction of low grade deposits. Water intensity of mining activities in a context of water scarcity, and the environmental and health implications of mine tailings are existing challenges, which are only made worse by the progression to lower grade orebodies. There is therefore also an interest in safer, cleaner and less wasteful extraction and production to ensure community well-being and environmental resilience."

Jan 1, 2018

By T. Wallmach, S. B. Blancher, A. Delaporte, P. Goncalves

"Fe-Ti oxides concentrates produced from heavy mineral sand deposits are widely used for the production of titanium dioxide pigments that are critical components of white paint, plastics and paper. According to mining industry, the Fe-Ti concentrates mostly consists of three phases: ilmenite, leucoxene and rutile. However, a few mineralogical studies have shown that the variety of Fe-Ti oxides found in sand deposits is far more complex, mostly due to alteration processes. The aim of this contribution is to characterize in detail by means of Qemscan analyses the mineralogy of the three main concentrates (ilmenite, leucoxene and rutile) produced by the Grande Côte Operation (GCO) mineralurgical plant in Senegal. The ultimate goal is to characterize the different products and textures formed during the natural ilmenite alteration processes, to localize the phases carrying the main impurities (Cr and P), and finally to determine the physical properties of each mineral component to improve metal recoveries. Along alteration processes, Ti content increase. Ilmenite (FeTiO3) is progressively transformed into pseudorutile (Fe2Ti3O9) particles which could also be altered and transformed into hydroxylian pseudorutile [FeTi6O12(OH)3.3H2O] or complex blends of anatase microcrystals (TiO2). These transformations are accompanied by significant changes in particle textures. Microporosity and fractures appear and the impurity content also increases. Anatase rich microcrystal assemblages, so far described as Leucoxene, could be identified to consist of grains with higher porosities, water contents and higher intrapore impurities. These particles are the main carriers of chromium and phosphorus. The observed mineral transition textures have a significant impact on the ore dressing processes. During these transformations, the physical properties of these phases change, the magnetic susceptibility as well as densities decreases, due to the increase in porosity. The separation of particles, especially those with high porosity will help improving the GCO mineralurgical plant performance and to reduce the impurity contents in finals products."

Jan 1, 2018

By N. Birbilis, S. Kairy, C. R. Hutchinson, D. Jiang, D. R. Feenstra, O. Gharbi

"Recent developments in metal-based additive manufacturing (AM) technology have generated considerable interest in multiple industries, owing to flexibility in design and the ability to produce final components in their net shape. The AM of high-strength aluminium alloys has not been widely explored, due to findings of undesirable microstructures leading to short fatigue life and poor fracture toughness; restricting the application of AM to lower strength aluminium alloys (with cast-like Al-alloy compositions) to date. Herein, aluminium alloy AA2024 (Al-3.6Cu-1.2Mg) was additively manufactured via selective laser melting (SLM), with the resultant microstructures and corrosion properties characterised and compared to wrought AA2024-T3. Microstructural characterisation was carried out using transmission electron microscopy (TEM), revealing SLM produced AA2024 included a population of ?-phase (Al2Cu) in preference to S-phase (Al2CuMg) typical of wrought AA2024. Additionally, the corrosion properties were investigated by potentiodynamic polarisation in a range of NaCl concentrations, whilst elemental corrosion rates were also determined (including for open circuit exposure conditions) and quantified in situ with an inductively coupled plasma mass spectrometer coupled with an electrochemical flow cell. Results revealed a significant improvement in the corrosion resistance, and elemental dissolution of AM prepared 2024 relative to wrought AA2024-T3.INTRODUCTION Aluminium alloys remain the preferred candidate materials in applications requiring a balance of low density and strength. The ability to produce net shape components from aluminium alloys has accelerated due to recent developments in metal-based additive manufacturing (AM) technology, including selective laser melting (SLM) and powder bed 3D printing. The AM of Al-alloys, including Al-Si-Mg (namely AlSi10Mg), has become widespread commercially in recent years. Alloys including AlSi10Mg offer reliable and reproducible production by AM, however such alloys (and variants thereof) are not high strength alloys. The pursuit of higher strength AM Al-alloys presents significant merit to multiple industries; however, such higher strength AM Al-alloys have not been widely studied to date. The solidification of high strength Al-alloys during conventional (casting) operations needs to be executed in a manner that avoids so-called =hot-tearing‘, which can arise as a result of the solute type and loading. A report on the solidification of a high strength Al-alloy prepared by AM, along with factors related to solidification, was recently covered by Pollock and co-workers (Martin et al., 2017). It was reported that AM of high-strength aluminium alloys (which have to date been principally based on the compositions of wrought high strength Al-alloys) may lead to undesirable microstructures that reduce fatigue life and result in poor fracture toughness; presently limiting the application of AM to lower strength aluminium alloys (with cast-like Al-alloy compositions) to date."

Jan 1, 2018