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By T. Yamazaki, T. Goto, R. Arai, N. Nakatani

The importance of cobalt-rich manganese crusts on the Pacific seamounts for possible future rare metal sources has been recognized these 30 years. The thin layer-type coverage and the micro-topographic undulation of basement affect not only the excavation efficiency but also the economy of mining venture. Because of these distribution characteristics, no economic feasibility has been recognized through the past economic analyses. On the basis of a recent geological study about seamount rocks, a possibility of by-product substrate recovery for phosphorous supply with cobalt-rich manganese crust mining has been highlighted. In the mining model, the substrate rocks are utilized as phosphates for agricultural and chemical usages. Under some preliminary technical and economic assumptions, the possibility of cobalt-rich manganese crust mining venture is examined. The results show a better economy of the venture including the substrate rock usage for phosphorous supply. Introduction Cobalt-rich Manganese Crusts and the Economic Feasibility Cobalt-rich manganese crusts on the Pacific seamounts received attention as potential sources for strategic metals such as Co, Ni, Cu, and Mn, due to their vast distribution and higher cobalt concentration than manganese nodules (Cronan, 1980; Halbach, 1982; Manheim, 1986). In the earlier stage, the geological distribution characteristics were reported (Cronan, 1984; Clark et al., 1984; Misawa et al., 1987; Pichocki and Hoffert, 1987) and a systematic feasibility of the mining was studied (Hawaii DPED, 1987).

Jan 1, 2018

By Feiya Xu, Syd S. Peng

"As a highly efficient and new surveying and mapping technique, 3D laser scanning technology has been gradually applied to surface subsidence monitoring in mining areas. 3D laser scanning technology was used to monitor the mining subsidence in a coal mining area in this paper. Based on the 3D laser scanning data obtained in March, May, and December 2016 in the studying mining area, the surface subsidence basin and points deformation were acquired. The 3D laser scanning data were compared with that of the conventional surface movement surveying method. The results show that the 3D laser scanning technology could obtain the data of the subsidence basin more efficiently and reflect the true shape of surface subsidence caused by mining. The maximum surface subsidence obtained by 3D laser scanning technology was 3.60m, while the conventional surface movement surveying was 3.56m; the relative observation error between 3D laser scanner and the conventional surface movement surveying was less than 10%. Therefore, it is feasible to apply 3D laser scanning technology to monitor surface subsidence in coal mines.INTRODUCTIONWith the over-exploitation of coal resources, the problem of surface subsidence has become the focus of attention (Peng, 2011; Guo Wenbing, 2012). Setting up observation stations for surface movement was the traditional method to study the characteristic of surface subsidence and its parameters. At present, hundreds of observation stations have been set up in longwall mining, and a large number of measured data have been obtained (Ministry, 2017). However, due to the length of time surveying requires, great workload in the field, the high cost of observation, and difficult protection for monitoring points, conventional observation stations for surface movement have not met the research on surface subsidence. Therefore, as a new surveying and mapping technique, 3D laser scanning technology has been gradually used for surface subsidence monitoring in mining areas (Ma Liguang, 2005). Li Qiu, Qin Yongzhi, and Li Hong (2006) first proposed 3D laser scanning technology in the application of monitoring surface subsidence in 2006. It was showed that the 3D laser scanning technology had obvious advantages in efficiency and accuracy of data acquisition than other methods of deformation monitoring technology of surface subsidence (such as total station, precision level technique, GPS, etc.). Subsequently, Zhang Shu, Wu Kan, and Wang Xiang (2008) and Chen Ranli and Wu Kan (2012) analyzed the feasibility and precision of 3D laser scanning in subsidence monitoring, concluding that the 3D laser scanning can be used to obtain the subsidence basin and the monitoring precision can reach millimeter. Hu Dahe, Wu Kan, and Chen Ranli (2013) introduced the data processing method of 3D laser scanning for surface subsidence in detail. On the basis of a case study, the subsidence basin in subsidence area was obtained, which reflected the shape of mining subsidence basin intuitively and comprehensively. Wang Qisheng, Wu Kan, and Zheng Ruyu (2010) carried out the research on prediction parameters of mining subsidence by using 3D laser scanning data and got the parameters of major influence angle and the offset distance of inflection point. Meng Wanli, Cai Lailiang, and Yang Wangshan. (2017) made a profile analysis for the 3D view of the surface subsidence using 3D laser scanning data and put forward a “Geomagic” method of surface subsidence prediction."

Jan 1, 2018

By John Jiang, Brian R. Hart, Stamen S. Dimov, Aparup Chattopadhyay, Barun K. Gorain

"This paper presents a systematic approach to metallurgy diagnostics using an integrated gold deportment methodology developed for complex refractory gold and copper-gold ore bodies. Quantification of gold deportment for these ore bodies is a challenging task due to reasons such as lower grades, high variability of visible and invisible gold content in different sulphides and iron oxide phases, significant presence of disseminated and composite carbonaceous matters along with associations of various copper sulphide phases. Some case studies are presented in this paper to demonstrate the value of a high confidence gold deportment methodology in developing insights for problem diagnostics and to identify opportunities for metallurgical improvements. A holistic approach involving different fields of expertise is critical for successful development and delivery of solutions for complex ore bodies.INTRODUCTION Studies were initiated on various ore complex ore and also on samples representing various process streams. These complex copper-gold single refractory, double and triple refractory gold ores are mainly composed of silicates and/or carbonates with moderate amounts of clay and mica, along with minor amounts of sulphides and organic carbonaceous matter. Variable proportions of visible gold and “invisible gold” (sub-microscopic gold) were noted in different mineral phases for various ore types and process stream samples. Invisible gold commonly occurs as solid solution or as colloidal-sized particles in different sulphides (pyrite, arsenopyrite, pyrrhotite, chalcopyrite and galena) and other phases (including hematite, magnetite and goethite) for different refractory ores. The dominance of invisible gold and presence of highly preg-robbing along with finely disseminated carbonaceous matters adversely affects gold recovery in flotation and leach circuits for most of these double and triple refractory ores. This paper discusses applications of an integrated gold deportment technique developed for different types of gold and copper-gold ores, namely, complex copper-gold, double and triple refractory gold ores (Chattopadhyay and Gorain, 2014; Chattopadhyay et. al., 2016). Various process streams from flotation and gold leaching circuits were investigated. Different concentrates and tailings samples from flotation circuits whereas feed and discharges from pressure oxidation (POX) and carbon-in-leach (CIL) residues were used from gold processing circuits."

Jan 1, 2018

By B. Gorain

"INTRODUCTION The last few decades have seen some remarkable advancement in information technology, but recently various digital technologies have resulted in several synergies to deliver innovation in diverse applications. The mining industry has been relatively slow in adopting these technologies compared to the other industries, but this scenario is changing fast. Keywords: Digital Transformation, Operational Intelligence, Gold Recovery, Mine to Mill integration, Planning and Execution strategy, Theory of Constraints. Challenges Mining companies globally are going through a series of challenges such as declining ore grades with complex metallurgy, increasing depth of ore bodies, high capital and operating costs, lower productivity, shortage of technical resources, significant pressure from stake-holders to deliver, along with growing environmental and corporate social responsibility issues. Improvement in profitability would need significant improvements in operational performance. Consequently, over the last few years, there has been a major focus amongst some mining companies to imbibe Operational Excellence. This has been only possible because of the replacement of a silos based approach by an integrated view of the organization. Such an integrated view is now possible via the evolving digital technologies. Even so, such a transformation calls for a change in culture, which, for most organization is not trivial. Attempts in the past to integrate functions such as through Mine-to-Mill initiatives in the mining industry have demonstrated significant benefits to many operations (McKee, 2013). Still, sustaining these benefits has clearly been a challenge due to manpower turn over and lack of proper systems and structures that integrate information between business functions within an operation and between operations and the corporate.Opportunities The advent of digital technology has opened-up opportunities to integrate inter-departmental information for a unified understanding of, and across, an entire organization. The advances in instrumentation, equipment control systems, supervisory control systems (SCADA/Historian) and industrial networks have helped in the direction of enterprise wide integration. The availability of real time information across an enterprise has given rise to numerous possibilities to improve organization performance. As suggested by Seshan & Gorain (2016), some of the potential opportunities are as follows:"

Jan 1, 2018

By Roberto Galéry, Braz J. C. Filho, Marcelo M. Stopa, Douglas B. Mazzinghy, Priscila M. Esteves

"The purpose of the research is to monitor ball mill filling by means of signals usually measured in its electrical drive. The method is based on the mill torque estimated from rotor speed and induction motor stator voltage and currents. New signal processing is presented in both time and frequency domain for measurements in a dry laboratory ball mill. Statistical analysis is applied to time series resulting in good correlation to mill filling. Fast Fourier Transform (FFT) and power spectral density (PSD) also resulted in an accurate filling indicator. The proposed method does not need any sensor to be installed directly on the mill and requires only sensors usually available for motor control purposes. The experimental results showed that the method have potential to be used to construct an automatic system for monitoring operational variables in ball mills. The aim of this monitoring is to improve energy efficiency, reliability and productivity.INTRODUCTION Recently, a great number of papers have pointed the importance of ball mill filling monitoring and also of grinding control (Lu, et al., 2014) (Ramasamy, et al., 2005) (Tsamatsoulis, 2014) (Zhou, et al., 2009). Additionally, great amount of control techniques have also been presented with several complexity degrees (Tsamatsoulis, 2014). According to Eremenko (2015) the lack of effective and accurate methods for fill level measurement is the main reason that makes mill optimal control so complicated. It happens because nonlinearity, long time delay and time varying features of the ball mill turns difficult to develop a truly efficient method for monitoring filling. At the same time, fill level has a determining role in charge motion and consequently on particle breakage. For low levels of filling many energy is expended in impacts with very low breakage efficiency. Those impacts can also damage mill liner. In contrast, high levels of filling causes damping effects that reduces breakage and can also affect energy consumption. Based on this it is conclusive that fill level measurement of ball mills is an important issue for grinding efficiency. This fill level information can be used for operators to control ball mills and also for engineers to run simulations and improve confidence levels of circuit designs (Shi, 2016)."

Jan 1, 2018

By Hong Zhong, Shuai Wang, Zhanfang Cao, Ting Dai

"Manganese is widely used in industries such as the steel industry and is now an essential element in modern industry. Technologies for the efficient and clean utilization of manganese resources must be developed and employed to ensure the sustainable growth of the manganese industry. Our research focuses on the use of beneficiation technologies to improve the grade of ores or the replacement of low-grade manganese carbonate ores with high-grade manganese oxide ores, and thus, to reduce reagent and energy consumption and the yield of electrolytic manganese residues from metallurgical processes; the study of leachate purification technologies; the study of electrochemical behaviors during electrolysis and energy-saving electrolysis methods; the development of chromium-free passivators as alternatives to the highly toxic potassium dichromate passivator; the non-hazardous treatment and resource utilization of electrolytic manganese residues and other manganese by-products; and the development of new manganese products. INTRODUCTION Manganese is widely used in the steel industry, nonferrous metallurgy, the chemical industry, electronics, batteries, agriculture, etc. Globally, more than 90% of manganese is consumed by the steel industry, and thus, it is said that ""No steel industry without manganese""(Banerjee et al. 2017, Zhang et al. 2017). Current manganese resources mainly include manganese ores, marine manganese nodules and waste catalysts. The total global output of manganese ore from land deposits is 18 million tons (metal volume), and the reserves, most of which is in the form of manganese oxide ores, are estimated to be 620 million tons (metal volume). More than 400 manganese ore deposits with a total reserve of 1.22 billion tons have been discovered in China. These deposits are predominantly manganese carbonate ores. Marine manganese nodules exist on the surface of the deep seabed at depths of 2000-6000 m. These nodules, which are also called polymetallic nodules, manganese balls, manganese aggregates and manganese tumors, are mainly composed of iron and manganese oxides. The total reserves of these resources add up to more than 3 trillion tons. Furthermore, the manganese in manganese-containing catalysts can be recycled after they become inactive."

Jan 1, 2018

By A. G. Bulaev

Biohydrometallurgical technologies based on activity of acidophilic microorganisms oxidizing ferrous iron, sulfur, and sulfide minerals are widely used to extract base and noble metals from sulfide ores and concentrates. As sulfide minerals oxidation is exothermic, industrial processes are usually preformed at 40–50°C. Moderate thermophiles predominate under these conditions. Most of moderately thermophilic acidophilic microorganisms that oxidize metal sulfide are mixotrophic, i.e., they use both organic nutrients and CO2 as carbon sources. Carbon availability is crucial for microbial activity and affects efficiency of biohydrometallurgical processes. Aeration with CO2-enriched air is often used to increase microbial activity in biooxidation reactors. Organic nutrients can be used as alternative carbon source for moderately thermophiles performing biooxidation of sulfide concentrates. We performed several experiments with different sulfide concentrates to study effects of organic carbon sources on biooxidation efficiency and demonstrated that application of such organic nutrients as yeast extract (YE) and molasses made it possible to increase biooxidation efficiency. For example, addition of 0.02% YE in the nutrient medium increased biooxidation rate of pyrite–arsenopyrite gold bearing and chalcopyrite concentrates in batch mode at 45°C. YE addition increased oxidation rate of sulfide sulfur and gold recovery level from 65 to 87% and from 73 to 81%, respectively. Similarly, YE addition increased copper extraction from 47 to 54%. At the same time, YE addition increased efficiency of biooxidation of pyrite–arsenopyrite gold bearing concentrate in continuous mode. Without YE addition, oxidation rates of pyrite and arsenopyrite were 65.7% and 94%, while gold extraction was 71%. YE addition (0.02%) made it possible to oxidize 74% and 95 % of pyrite and arsenopyrite and extract 78% of gold. Addition of molasses (0.02%) similarly affected biooxidation efficiency. Thus, addition of organic nutrients in nutrient media is a promising strategy for improvement of biohydrometallurgical processes.

Jan 1, 2018

By Sam Yao, Ali Naeem, Sara Barrett

Brooklyn Basin Project is a multi-billion-dollar development of the former Port of Oakland 9th Avenue Terminal located along the Oakland Estuary of California. A centerpiece of the development is the 10-acre shoreline park which will be built on a 1,200 ft long by 225 ft wide historic wharf. The wharf was built in the 1930’s on concrete and timber piles with a flat concrete slab. Prior to constructing the wharf, a rock dike was placed to protect the shoreline. The presence of the rock dike increased the hazards from lateral spreading of the underlying bay mud and non-ductile shear failure of piles driven through the dike. To open the park to the public, the wharf required a seismic retrofit in compliance with the California Building Code. The paper presents the results and conclusions of the following topics: • Structural condition assessment and repair strategies for the existing wharf deck, piles and jackets • Application of the California Building Code (CBC Ch31F) for the performance-based seismic evaluation of existing piers and wharves • Nonlinear pushover analysis of the wharf including the combination of inertial and kinematic effects • Impact of rock dike on lateral spreading and kinematic effects and the significance of existing piles in stabilizing the lateral spreading of the rock dike • Retrofit strategies for the wharf to meet the required seismic performance requirements per the California Building Code and reduce the demands on existing piles which were driven through the rock dike INTRODUCTION The 65-acre Brooklyn Basin Development project is located in Oakland, California. The project consists of 3,100 housing units, 200,000 sq. ft of retail and commercial space, along with various parks and public access improvements along the Oakland Estuary. A centerpiece of the development is the 10-acre Shoreline Park which will be built on a 1,200 ft long by 225 ft wide historic wharf. The wharf was built in the 1930’s on concrete and timber piles with a flat concrete slab. As shown in Figure 1, the wharf deck and piles support the 9th Avenue Terminal Building.

Jan 1, 2018

By P. Oliveira, A. Peres, A. Silva

"The decrease in iron content and increase in contaminants grade, associated with greater participation of compact and semi-compact materials, has impacted the recovery of a mechanical cells flotation circuit in the Iron Quadrangle, Brazil. The recovery decrease in the flotation stage motivated the current conventional flotation circuit reevaluation seeking alternatives to restore the recovery, without affecting the final concentrate quality parameters, with low investment. Sampling, chemical characterization of samples, bench scale flotation experiments, and mass balances were conducted. Analysis of the results showed opportunities to improve the circuit performance. The stages prior to the flotation circuit changes were: rougher, cleaner, recleaner and scavenger. In the previous configuration, recleaner was operated as cleaner scavenger and the iron grade in the scavenger concentrate was 23%, representing 38% of the new feed. After the circuit change, the circulating load was reduced from 38% to 15% and the iron content was upgraded to 42%, resulting in increased residence time. The iron content in the global tailings of the concentrator was decreased from 10.9% (year of 2013 average) to 10.2%, representing gains in both mass and metallurgical recoveries.INTRODUCTIONRegarding plant practice, the year 1972 represents a landmark for the concentration of iron ores in Brazil. VALE started up 28 units of WHIMS (wet high intensity magnetic separators) at the Cauê plant in Itabira, each one producing 1x106 t/year of concentrate. Later 17 WHIMS machines were commissioned at Conceição. During the 80’s decade of last century, changes in the ROM required the addition of a cleaner flotation stage to decrease the silica content in the pellet feed.The first company to use reverse cationic flotation as the only concentration operation of iron ore was SAMARCO (start up in 1977). Since 2015 flotation has been utilized at VALE in Itabira as major concentration process, magnetic separation acting as scavenger stage.The Jones matrix type WHIMS were manufactured for decades under patent by KHD Humboldt Wedag. After the expiration of the Jones patent, Eriez Magnetics took the world leadership regarding WHIMS manufacturing. The Brazilian branch of Eriez is Inbras. Based on plant practice experience at the Fabrica concentrator, the Brazilian company Gaustec was established (RIBEIRO and RIBEIRO, 2010) and is now present in different countries. The mega sized WHIMS GHX-1400 (18.000 Gauss, gaps smaller than 1.5 mm) were developed to face the challenge of huge throughput required by iron ore processing (Ribeiro et al, 2017)."

Jan 1, 2018

By G. V. Kalabin

"The paper supports applicability of satellite imagery at regional and local level for rapid quantitative assessment of natural environment in zones of activity of mining complex enterprises. Exacerbation of environmental problems during mineral mining and processing associated with their scale and geography of field distribution through the vast territory of our country requires constant monitoring of natural environment status, which necessitates engagement of space surveillance nowadays. It is proposed to use the monitoring of land cover and land use at regional and local level for the environmental assessment of a particular production or complex productions. You must establish the dependence of NDVI change trend with the magnitude of anthropogenic impact on the source or multiple sources of environmental pollution a particular area.. We present the results of studies of vegetation remote sensing methods in a number of territories placing mining enterprises. INTRODUCTION Ensuring a healthy environment is necessary both in untouched areas and disturbed. The condition of the developed territories should be monitored with particular attention, since the restoration of the disturbed territories requires great efforts and financial costs. More narrowly, the health of the environment (Zakharov V.M. and etc.,2001) means its quality ensuring the health of man and other species of living organisms, which includes two aspects (Zakharov V.M. and etc, 2000): - ensuring an environment conducive to human health as a biological species: - maintaining the health of the natural environment, i.e. its constituent species of living organisms and plants. The consequence is the disturbance of natural ecosystems, which determines the quality of the environment, favorable for human habitation and the state of health of the population in total determine the status of the territories where enterprises for the development of georesources are located and allow them to be ranked according to the degree of environmental danger. Without knowledge of the trajectory of ecosystem successions, it is impossible to offer adequate requirements for the technologies used to ensure the implementation of the preserved natural potential after the removal or reduction of man-made stress."

Jan 1, 2018

By V. F. Bannikov, A. P. Kozlov

"The purpose of this study was to develop a theoretical and technology framework for designing new combined technologies for processing tailings containing non-ferrous and noble metals using dry separation. The main goals of the study were: identifying the distribution patterns of valuable components in various fractions in dry separation processes; examining the patterns identified for different types of non-ferrous and noble metal tailings; developing a theoretical and technology foundation for the development of innovative technologies for the efficient processing of tailings with minimal process water consumption. To examine the possibility of efficient recovery of valuable components from refractory tailings using dry separation, an experimental laboratory unit was designed and built, composed of novel or modified lab equipment: plasma unit for increasing the magnetic susceptibility of Fe - containing minerals; magnetic separator supporting isodynamic and polygradient fields; pneumatic separator for the dry separation of finely dispersed mineral mixtures; dielectric separator using the resonant frequency of the electric field. The laboratory unit supports various modifications and combinations of the lab equipment. The experimental studies led to the development of a unified process scheme for lab tests of mature and non-ferrous smelter tailings using dry separation methods.INTRODUCTION The huge amount of waste from mining and processing of mineral resources Russia inherited from the extensive use of mineral resources in the Soviet Union and amount of waste continue to grow. Often the content of valuable non - ferrous, rare and noble metals in waste exceeds the balance contents in natural ores of the developed deposits. The availability of a rich scientific reserve for the creation highly effective innovative technologies for waste processing determines the necessity of the acceleration in the resolution of problems of the complex assessment, capitalization and involvement in the processing of technogenic resources in Russia (Chanturiya and Kozlov, 2014.)."

Jan 1, 2018

By M. Holuszko, I. Mikhalev

"Previous studies described by Galvin et al. (2017) have shown that for Australian bituminous coal fines, both in batch and in continuous process, the new improved oil agglomeration procedure based on the use of high-internal-phase (HIP) emulsions, as compared to the conventional “pure oil” agglomeration process, enables a significant reduction in the amount of oil while reaching a high yield of clean coal (approximately 90% of agglomerates greater than 355 µm in size) in a significantly shorter time. The HIP emulsion used in these experiments comprised up to 95% vol. aqueous solution of sodium chloride (3% wt. concentration) and for the rest, a mixture of kerosene (oil) and sorbitan monooleate (SMO emulsifier) in a 1:1 ratio as a binder. This study evaluates the applicability of the new HIP-oil agglomeration process to treat Canadian bituminous ultra-fine coal and Russian sub-bituminous coal fines and compares results from agglomeration to the flotation response of both coals. Oil agglomeration is known to be sensitive to surface properties of coal. Since surface properties of coals depend not only on the rank of coal but also on their origin (depositional environment) and mineralogical composition, both the applicability of this new improved agglomeration process to the non-Australian coals and its efficiency became the motivation for this study. To evaluate the applicability of the new process to both Canadian bituminous and Russian sub-bituminous coals, a series of bench-scale tests were carried out under conditions similar to those described by van Netten et al. (2016) for the Australian coals. Based on the results obtained in this research, new boundary conditions for the application of the HIP emulsion-based oil agglomeration process have been outlined and conclusions on the viability of the new process to treat ultra-fine coal from Western Canada and Russian sub-bituminous coal fines have been reached.INTRODUCTION In most cases, to meet the market requirements, the mined coal has to be processed to reduce the ash content by the removal of mineral matter and thus to increase the quality of the coal products (van Netten et al., 2016). Generally, flotation is used for processing fines from high rank coals; however, there are high losses of very fine coal due to the inefficiency of this process. Furthermore, difficulty in dewatering the fine coal results in excessive moisture levels causing coal handleability issues, which increases costs in the coal-cleaning industry (Capes & Darcovich, 1984). Much of the development that has occurred in fine coal cleaning has taken place with higher-value coal, often metallurgical (Klima et al., 2012). If the fine coal is deemed to be too difficult or expensive to process, it may be discarded as waste (van Netten et al, 2014). Such disposal not only creates an environmental liability but may also result in the loss of a valuable, high quality product that is better liberated than the coarser fractions of coal."

Jan 1, 2018

By M. C. Harris

"In the flotation process the contact angle is an important indicator of the hydrophobicity of a mineral particle. There is considerable literature showing that the contact angle increases when the chain length of the alkyl group associated with the collector molecule used to render the valuable mineral particle hydrophobic increases. The extent to which an alkyl group interacts with surrounding water molecules is quantified thermodynamically by the excess Gibbs energy. In the present paper it is shown that there exists generally a strong linear relationship between the excess Gibbs energy of the alkyl group associated with the collector and the contact angle. The structure-activity of such alkyl groups is in turn related to the total surface area, molecular volume, the molar volume, molecular weight of the functional groups in the molecule and interaction energies. It is proposed that the demonstrated relationship is indicative of the role which the alkyl group component of the collector, which is attached to the mineral particle, plays in increasing the extent to which water molecules at the surface of the mineral are rejected from the surface thus increasing the contact angle. The relationship between excess Gibbs energy and surface tension is further explored with a view to relating the observations quantitatively to the parameters in the Young equation.INTRODUCTIONThe issue of wettability of materials is of great importance to many industrial applications. Wettability studies usually involve the measurement of contact angles which indicate the degree of wetting when a solid and liquid interact. As is well known the contact angle (O) is the angle between planes tangent to the surfaces of the solid and the liquid at the wetting perimeter which is the zone where the air, water and solid phase merge. When the air bubble attaches to the solid surface there is an increase in the air/solid interface area and a decrease in the solid/water interface area. For attachment to occur the cosine of the contact angle should be less than 1 and this will be promoted if the interfacial surface tension between the air and the solid (? SV) is low. Classically the relationship between these parameters has been expressed through the Young equation (1) for a perfectly flat surface:"

Jan 1, 2018

By I. Nishkov, I. Grigorova, M. Ranchev, S. Dzhamyarov

"Chelopech concentrator (part of Dundee Precious Metals) is located in central-western Bulgaria. The current process plant utilizes conventional primary crushing and SAG mill grinding, copper and pyrite rougher and cleaner flotation stages to produce a marketable gold-rich copper and pyrite concentrates. As in the most processing plants, the pyrite depression is carried out alkaline media using lime. The subsequent activation of pyrite mineral is achieved by adding sulfuric acid, which has an adverse effect on the flotation equipment. Therefore, a series of laboratory flotation experiment for activation of lime depressed pyrite by ammonium salts, such as ammonium chloride (NH4Cl), ammonium sulfate (NH4)2SO4 and ammonium bicarbonate (NH4HCO3), have been conducted. The obtained results showed that ammonium bicarbonate proved to be the most appropriate reagent choice for pyrite mineral activation. These results are confirmed by X-ray photoelectron spectroscopy (XPS), performed to determine the surface chemistry of pyrite in its natural state, after lime treatment and subsequent treatment by NH4HCO3. The registered XPS spectra indicate that the hydrophilic phases on the pyrite surface could be efficiently removed by using the ammonium salt NH4HCO3. The industrial use of NH4HCO3 as an activator of lime-depressed pyrite is a possible alternative for sulfuric acid replacement as a most widely used pyrite activator. Flotation experiments with addition of 200, 400, 600 and 800 g/t from each of the studied ammonium salts have been conducted. Furthermore, the impact of the flotation pulp pH within the scope of 9.00 – 10.50 was also investigated. The obtained results from the laboratory flotation experiments, showed that the pyrite activation with ammonium bicarbonate is an excellent possibility for replacing the sulfuric acid as main pyrite activator reagent, in order to eliminate the gypsum accumulation during the flotation of pyrite in Chelopech concentrator.INTRODUCTION The Chelopech deposit, located about 60 km east of Sofia is one of the largest Cu-Au deposits in Europe. The ore have complicated mineralogical and chemical composition. The main ore minerals are represented by pyrite, enargite (luzonite), tennantite, chalcopyrite and bornite. The average copper content of the mined ore is about 1.1 % and the gold content is about 4.0 g/t."

Jan 1, 2018

"Mining used to be a business primarily focused on the technical aspects of getting valuable ore out of the ground and extracting the minerals efficiently. Without denying the importance of these skills, a narrow focus on technical issues is no longer enough to guarantee success when it comes to exploiting rare earth element (REE) deposits. Molycorp failed to enter the global REE market in a successful manner, while none of the many REE exploration projects has turned into an active mine so far and none is expected to commence operations in the near future. Accordingly, the world of REE is far more complex compared to other commodities. This paper looks into the REE industry to identify the factors that can connect potential U.S. REE mines to the market. The ability to break free from past thinking and become future-focused is a key driver. Mining of REE is pointless without a corresponding value-adding chain, while developing a value chain without first establishing an uninterruptible source of REE is also senseless. The mining sector must be based on the REE value chain and vice versa, along with the establishment of a market channel for the REE products that come out of the mine. INTRODUCTION It has been seven years since rare earth elements became the subjects of front-page headlines. It was when the controversial Chinese export policy for these critical commodities was epitomised in a maritime border dispute with Japan in September 2010 that resulted in the big REE crisis and price spike of 2011 (Barakos et al, 2016c; Mancheri, 2015). The world was dismayed, especially in REE-importing countries, such as the United States that was and is still totally dependent on Chinese production and exports (Barakos et al, 2016c; Kennedy, 2015). The short-lived alarm initiated a treasure hunt by way of exploration for REE deposits all over the world. The continuously growing demand on the one hand and the Chinese sovereignty of the REE-market on the other, led the rest of the world to explore their own REE resources. In just a few years, more than 400 projects were initiated to explore REE deposits outside of China (ERECON, 2015; Goodenough, 2016). The prices of REE, however, dropped rapidly and at the moment of writing this paper are in 6-year lows, at the level of the price average before the 2011 crisis (Barakos, 2017). The viability of even major established producers is being challenged, not to mention the development prospects of potential REE-market entrants (Barakos et al, 2016b; Rollat et al, 2016). Production cutbacks and industry consolidation in China impel REE market experts to forecast that prices have already reached their lowest point and have nowhere to go but up (Adamas, 2015; Roskill 2015). Yet, expectations for increased REE prices are limited and drastic changes are unlikely to happen in the near future, as there is still excess supply in the overall REE market (Barakos, 2017). Nevertheless, the low prices of rare earths are not the only reason that potential producers are struggling to enter the global REE market. Among other parameters, the separation of the individual elements seems to be the most important factor, as it is technically challenging and expensive to build and to operate."

Jan 1, 2018

By T. Fraszczak, U. A. Peuker, T. Mütze, T. Leißner, A. Wikedzi

The present paper highlights on the comminution and liberation properties of two greisen-type lithium bearing-mica ore blends (L1, L2) subjected to different breakage devices; cone crusher (CC), roller crusher (RC), rotor beater mill (RBM) and a screen mill (SM). The particle size distribution (PSD) of the products from each device were evaluated to search for an appropriate PSD model using Gates-Gaudin-Schuhmann (GGS) and Rosin-Rammler (RR) functions. In order to determine an appropriate function that could better describe the PSDs from the devices used, the coefficient of determination (R2) was used as a criterion. In terms of mineral liberation studies, due to costs, only products from rotor beater mill (RBM) were examined through an automated scanning electron microscope (SEM) technique. It was found that RBM, RC and SM products were better described by the RR model than the GGS model with higher R2 values (0.97-1.0). However, cone crusher products for L1 were better described by GSS model, while that for L2 were better described by RR model. In terms of the spread of size distribution as indicated by RR model parameters, RC products were more uniformly distributed compared to products from other devices, for both ore blends. Also the RBM products were more scattered than products from other devices. The results indicate that the composition of individual ore blends affected the comminution products PSDs since different PSD model parameters were obtained for samples comminuted by same devices. The modal mineralogy of the two ore blends indicate both to be rich in quartz, topaz, zinnwaldite and muscovite. Further, the result indicate that, for both ore blends, zinnwaldite phase is more enriched in the fraction < 250 µm. Moreover, better liberation of zinnwaldite is observed for L1 compared to L2. This could be explained by differences of the two ore blends in three aspects; the nature of mineral association, reduction ratio of the fractions analysed and the nature of spread of the size distribution.

Jan 1, 2018

By D. Saramak

"High-pressure grinding technology is considered as one of the most efficient techniques of ore comminution, especially in terms of energy consumption. HPGR devices has been utilized in many mining-related industrial sectors, including iron and non-ferrous metal ores processing (copper, platinum, gold), as well as cement and limestone flour production. Even though the technology well known (introduced into mineral processing circuits in 80’s), there are still examples of ineffective operation of HPGR devices. This is a result of improper application of HPGR into individual crushing circuit. The purpose of the paper was to analyze selected effects achieved in HPGR on the course and effectiveness of beneficiation operations. Investigations were carried out for copper ore, and investigative programme was run for different values of HPGR pressing force, as well as changeable ore characteristics (content of fine size fractions, material moisture). All crushing products were then treated in flotation process, in order to determine useful mineral recovery. Results of investigations show that HPGR operating pressure influences the metal recovery in proportional way, however too extensive pressure values have relatively lower impact on increasing of the metal recovery. Particle size distribution of HPGR feed and its moisture have lower influence on recovery level than HPGR pressure, but too extensive moisture content influences the higher energy consumption of the roller press, together with less effective comminution. The second aspect raised in the paper was a possibility to control and optimize the HPGR-based circuit. There were presented the proposed approach to adjustment of HPGR operating parameters that enables the higher metal recovery.INTRODUCTION The high-pressure grinding technology, invented and developed by Professor Schoenert in 70’s (Schoenert, 1979), is currently regarded as one of the most efficient methods of hard ore comminution. Since then the technology was introduced into raw materials treatment circuits in many mining and mining-related industrial sectors, including iron and non-ferrous metal ores processing (copper, platinum, gold), as well as cement and limestone flour production. Considerable number of works concerning modeling and optimization of HPGR operation were also presented (Daniel & Morell, 2004, Tavares, 2005, Saramak, 2012, Saramak & Kleiv, 2013). Nowadays high-pressure grinding rolls devices are considered as well know technology with over 500 sold machines, according to various sources."

Jan 1, 2018

By Y. S. Sun, P. Gao

"In this investigation, a pilot-scale suspension magnetization roasting reactor was introduced and used to enhance magnetic properties of an iron ore. Consequently, the effects of roasting temperature, reducing gas CO flow rate and fluidizing gas N2 flow rate on the magnetization roasting performance were investigated. The results indicate that the hematite and siderite are almost completely converted into magnetite by a gas mixture of 3.5 Nm3/h CO and 2 Nm3/h N2 at roasting temperature of 520 °C. Under the optimized conditions, the magnetic iron concentrate with an iron grade of 60.18% and iron recovery of 90.17% was achieved. The XRD and Fe mineral phase analyses revealed that most of the hematite and siderite were converted to magnetite, and the magnetic properties were greatly enhanced. INTRODUCTION The steel and iron industry in China has rapidly developed in recent years requiring a large quantity of iron ores. Low-grade and complex iron ores are currently the overwhelmingly dominant mineral resource for iron in China. Therefore, China depends on imported iron ore resources heavily, resulting in an increase in the production costs of iron-making and steel-making[1-3]. Using domestic resources to produce a steady supply of high-quality iron ores is an important step toward the sustainable development of the steel and iron industry[4-5]. The iron ore from Jiuquan iron and steel company is abundant and recognized as typically complex iron ore resources in China. Magnetization roasting followed by low-intensity magnetic separation has been proven as the most feasible methods to upgrade refractory iron ore[6-10]. In present research, an innovative roasting technology, namely suspension magnetization roasting, was developed and applied to recover iron from a typical refractory iron ore. Suspension magnetization roasting technique and equipment developed by Prof. Yuexin Han’s Group at Northeastern University (NEU) is an effective way for the utilization of refractory iron ore. The advent of suspension magnetization roasting will, in China and even globally, produce a significant technological revolution in the field of iron ore beneficiation. Based on the previous works, this paper mainly described experiments on the separation and recovery of iron from a complex refractory iron ore by means of suspension magnetizing roasting and low-intensity magnetic separation processes. The purpose of the research is providing a new technology for effective utilization of refractory iron ore. Process parameters that affected the separation and recovery rate of iron were conducted and optimized, and the reaction process was analyzed by XRD and Fe mineral phase analysis."

Jan 1, 2018

By J. Starkey

A comminution circuit in recent history, is one of the most difficult parts of a mineral processing plant to design with confidence. It is usually the most costly part of a plant to build, and it can consume up to half or more of the energy used on a mine site. To suggest that comminution energy usage is sustainable in the long term is not possible at this time. What we have to choose from today, based on more than 50 years of experience, does include the best available technology, and the best way to design it. There is controversy in the industry as to how to properly approach the subject of comminution design, with many of the optional solutions requiring a level of training and expertise beyond the ability of a non-specialist engineer. Semi-autogenous grinding technology in particular, has not been properly appreciated because of many recent mistakes in its application and design, which have blurred the positive perception about what SAG technology is, how it can be used, and how it needs to be designed and built. In order to change this, mine owners and senior managers need to take responsibility for, and learn to understand the fundamental challenges that a comminution circuit poses to the project, to the design process, to the operators who use the equipment, and to the resulting metallurgy. This address is intended to summarize these challenges and offer fundamental engineering solutions, which are clear, specific and in a format which is directly applicable to the mining and mineral engineering community.

Jan 1, 2018

By A. V. Bogdanovich, S. A. Urnysheva

"Gravity and X-ray luminescent separation methods are generally used in processing of diamond ores. X-ray luminescent separators are applied for separation of diamonds from feed ore size fractions from 100 to 10-15 mm size and for final treatment of gravity concentrates over 1 mm size. Gravity separation machines used for diamond ores separation are heavy medium cyclones and pneumatic jigs. One of the most important parameters, to a large extent affecting diamonds recovery from ore, as well as processing costs and specific energy costs, is size of dumped final tailings. That was exactly the purpose of the studies, the results of which are described in this paper. The studies performed on different ores showed that in order to achieve high recovery results, it is necessary to dump heavy medium separation tailings below 3 mm size. Separation of final tailings of -6+1 mm size by jigging is also possible. However, with a view to exclude extra diamond losses, it is necessary to maintain jigging concentrate yield approximately at 25% from starting feed, with its subsequent cleaning in heavy medium cyclones. In addition to that, it is necessary to separate 20-25% of middling with diamonds content at feed ore level and subject it to grinding. This will complicate flow sheet, but reduce load on heavy medium cyclones. In order to develop optimal flow sheet for gravity concentration of a specific diamond ore, large-scale investigations are required, including technical-and-economic assessment of separation alternatives. INTRODUCTION In processing of diamond ores, gravity and X-ray luminescent separation methods are generally used. It is common practice to apply X-ray luminescent separators for separation of diamonds from feed ore size fractions from 50 (100) to 20 (10) mm size and for final treatment of gravity concentrates over 1 mm size. With that, X-ray luminescent separation tailings larger than 3-6 mm size are reground and delivered to gravity concentration processing stage. Middling products circulation volumes are large, not infrequently necessitating decrease in concentrating plants capacity, especially with mining in deep workings of deposits, where ore strength is higher (Goryachev, 2010; Vaginov, 2000; William, 1988). Diamond ores preparation before processing is accomplished by means of roll-screw crushers and autogenous grinding mills, minimizing probability of free diamonds damage in liberation from barren rock. In re-crushing of size fractions that are “difficult” in autogenous grinding, high pressure grinding rollers are applied (Burchardt, 2014; Fedotov, 2011a, 2006b)."

Jan 1, 2018