Search Documents

By J. Dilbeck, J. K. Ratliff, T. Petrov, Z. Brown

"In efforts to improve dust control during deep cut continuous mining a supplemental atomizing spray system, mounted on 14CM15 continuous miner, has been designed and successfully implemented in a U.S. coal mine. The mine is 2.1 m (7-ft) high and uses a blowing curtain face ventilation system with 1.1 m (3.5-ft) curtain offset from the rib. The face ventilation design parameters were set to 9.4 m3/s (20,000-cfm); 4.2 m3/s (9,000-cfm) line curtain flow rate, and 3.8 m3/s (8,000-cfm) scrubber capacity. The performed in-mine measurements, before and after the implementation of the atomizing spray system, showed a significant decrease in the respirable dust levels at the operator place as well as at the return. The paper describes the supplemental water spray system design and performance supported by three-dimensional computational fluid dynamics (CFD) simulations and in-mine test data.INTRODUCTIONThe work on this project have started in 2015 with a study of the conventionally applied face ventilation layouts. The specific behaviour of the face ventilation system have been analyzed trough in-mine measurements and computer modeling of typical cut scenarios. An computer modeling methodology have been developed for estimation the respirable dust concentration (RDC) using tracer gas to RDC contour mapping, calibrated by a single point value, provided by in-mine measurement. Utilizing the results of this study the engineering staff of the mine designed and implemented a supplemental atomizing spray system to improve the dust control during the deep cut continuous mining. Today the atomized spray system is successfully applied demonstrating steady performance and a significant decrease in respirable dust concentration on the working places of the continuous miner (CM) and coal transporters (CT) operators as well as at the return air stream. Information about the applied type of spray nozzles provided by other researchers (Cheng, 1973; Dick et al., 1996; Organiscak & Page, 1998; Pollock & Organiscak, 2007) and spray system manufacturers (Spraying System Co, 2011–2018; Steinen Mfg., 2016) have been used in this project. CFD code and simulation approach validated in a study conducted in 2000-2014 have been applied (Turner et al., 2002; Wala et al., 2004, 2007; Petrov, 2014)."

Jan 1, 2019

By G. Q. Zhou, H. C. Liang, X. D. Zhao

"This study describes the strain behavior in vertical shaft lining (VSL) embedded in thick soil deposits and its application in assessment of concrete deterioration. The observed strain in VSL continuously decreased companied by a sinusoidal fluctuation due to the influences derived from negative skin friction (NSF) and temperature. The increase in strain increment between peak and trough at each year and compressive strain level as the servicing time continued and VSL depth increased implies that the concrete strength was attenuated, and this attenuation was significantly dependent on the existing compressive strain level in VSL. The reliability of the proposed approach was validated by Schmidt Hammer Technique (SHT) – based concrete strength, and is applicable in concrete assessment and then fracturing prediction of VLSs in thick soil deposits.Concrete strength, Field monitoring, Strain behavior, Vertical shaft liningINTRODUCTIONOver 100 VSLs in Southeastern China subjected to an unpredictable fracturing as shown in Figure1, and there are over 1,000 VSLs embedded in thick alluvium su?ering from challenges of damaging and potential fracturing (Cheng, Yang, Zhou, Li, & Hu, 1993; Zhou, Cui, Lv, Huang, & Chen, 1999; Li & Li,2005). Therefore, a reliable assessment of these VSLs is significant to the normal servicing of mine shafts and the recycle of underground space when these mine shafts were closed.The continuous increasing of NSF induced by the drainage of water–saturated deposits well interpreted such extensive fracturing phenomenon, and it is universally regarded as the governing indicator to determine the VSL stabilization (Cheng et al., 1993; Zhou et al., 1999). Based on this recognition, the fracturing prediction and VSL strengthening according to the field monitoring on hydrogeological characteristics, servicing environments, and mechanical behaviors of VSL were carried out (Zhao, Zhou, Zhong, Zhu, & Liang, 2009; Liang et al., 2009; Xie, Lv, & Wu, 2014). As known, the compressive strain level in VSL and the in–situ strength of VSL concrete were the main factors to perform such fracturing prediction. However, the existing studies in literatures were limited to the strain accumulating or releasing behaviors (Zhao, Zhou, Zhao, Kuang, & Hu, 2017), and lack of considering the VSL concrete strength and its attenuation. In this reported study, the in–situ monitoring data on the strain in typical VSLs and the VSL elevations between 2004 and 2014 were initially analyzed. Then, an observed strain behaviors–based approach was developed to quantitatively evaluate the VSL concrete deterioration."

Jan 1, 2019

By J. E. Nesset, E. R. Bobicki, K. L. Bilaniuk

The introduction of froth flotation technology in Canada, and in particular, in British Columbia, began not long after it was successfully applied in the Broken Hill mining area of Australia which began around 1905. It proved to be a revolutionary and transformative technology that resulted in marginal operations in copper, lead and zinc becoming profitable in spectacular fashion. The paper presents the technology of both oil flotation and froth flotation in the context of the challenges of the time and its early application in British Columbia at the Le Roi No.2 mine (1903), the Britannia Copper mine (1912), and at the Allenby concentrator of the Copper Mountain mine (1918-19). New-found archival documents indicate the Britannia application to be the first production application of froth flotation for copper ore outside Australia, a claim that is currently made by the Braden mine (now El Teniente) in Chile. Flotation was initially an add-on process following gravity methods but was rapidly shown to be far superior method for the bulk and selective recovery of metal sulphides. Flotation proved particularly successful for the recovery of zinc sulphide (the so-called ‘zinc problem’) which was considered a contaminant at the time. The ‘copper problem’ related to the poor recovery of fine copper sulphide particles that were not amenable to gravity methods. The success of flotation led to changes in both the scale and methods of mining, concentration and smelting in a manner that allowed integrated mining companies to flourish. Many are still with us today. INTRODUCTION The advent of froth flotation in the early 20th century was truly a revolutionary technological development, not only for the mining and metallurgical industries, but arguably more so for business and society overall. The Canadian technology historian Jeremy Mouat stated (1996) “The development of flotation was the greatest single metallurgical improvement of the modern era...it is not overstating the case to claim that flotation was of central importance to the smooth functioning of the global economy”. It should, therefore, be a story of interest to us all. The aim of this paper is not to retell the full story, that has been well covered by others (Hoover, 1912; Rickard, 1916a; Hines & Vincent, 1961; Lynch et al., 2010) but rather to add some Canadian perspective and the key role played by companies and individuals in those early days, focusing on events in British Columbia’s copper industry. EARLY DEVELOPMENTS During the later half of the 19th century, a number of flotation-related patents were issued. These include the 1860 patent (Britain) granted to William Haynes for a process to separate sulphides from ground ore by mixing it with oil (1-10% wt) followed by a separation process in a water-filled vessel; the 1877 patent granted to Georg and Adolph Bessel (Germany) for a process involving the mixing of oil and graphite ore followed by boiling in water to produce a high grade graphite froth (>90% carbon); and the 1885 patent granted to Rebecca ‘Carrie’ Everson for the separation of sulphides by mixing sulphide ore with small quantities of oil, and adding water followed by sulphuric acid. These processes are more properly referred to as bulk oil flotation due to the relatively large quantity of hydrocarbon used.

Jan 1, 2019

By P. C. Holloway, A. Tshilombo, T. Xue, M. J. Collins, R. Lopetinsky, I. Mihaylov, I. M. Masters

The Voisey’s Bay deposit contains a trace amount of cadmium, which reports to solution during pressure leaching of the nickel concentrate at Vale’s Long Harbour Hydrometallurgy Plant, and must be removed to produce high quality nickel cathode. In 2006, Vale approached Sherritt Technologies to collaborate on the development of a process for removing cadmium to low levels (<1 mg/L) in the nickel raffinate. Following successful bench scale and pilot plant testing at Sherritt’s laboratories, the cadmium removal process was then moved through engineering and construction, culminating in the successful commissioning and startup of a cadmium removal circuit at the Long Harbour Hydrometallurgy Plant in 2017. This paper presents the results of this collaboration and the challenges that were encountered through each stage of development, as well as current results from operation of the commercial cadmium removal circuit. INTRODUCTION Vale’s Long Harbour Processing Plant, with a nameplate capacity of 50,000 t/y nickel, began operation in 2014. In addition to electrolytic nickel rounds, the plant also produces electrolytic cobalt rounds and copper cathode. The Long Harbour Processing Plant uses a unique hydrometallurgical process developed by Vale Base Metals Technology Centre, as shown in Figure 1, to treat a nickel sulphide concentrate produced at the Voisey’s Bay mine and mill located in northern Labrador (VBN concentrate) (Stevens et al., 2009).

Jan 1, 2019

By K. C. Sole, G. Robinson, M. S. Moats, W. G. Davenport, S. Sandoval

Global practice in hydrometallurgical production of copper cathode by electrowinning is reviewed, based on individual plant operating data for 2018. Data from 29 plants were collected, representing 38% of world cathode copper production. Similar surveys were carried out in 1997, 1999, 2003, 2007, and 2013. This survey includes analysis of historical and current data. Evolving trends in operating conditions and performance, as well as equipment design and process technology choices, are analysed and differences in operating practices with location are assessed. Examples of recent technology and operational choices to increase productivity, improve copper quality, and decrease electrical energy consumption are discussed. Significant project expansions, particularly in Africa, and the consolidation of numerous small Chinese operations are also presented. INTRODUCTION Global trends and operating practices in copper electrowinning (EW) in 2018 are reviewed and evaluated. Similar world and African surveys were carried out in 1997, 1999, 2001, 2002, 2003, 2007, and 2013 (Robinson, Davenport, & Jenkins, 1997; Jenkins, Davenport, Kennedy, & Robinson, 1999; Davenport, Jenkins, Robinson, & Karcas, 2001; Robinson, Garbutt, & Davenport, 2002; Robinson, Davenport, Jenkins, King, & Rasmussen, 2003; Robinson, Davenport, Moats, Karcas, & Demetrio, 2007; Robinson, Sole, Sandoval, Moats, Siegmund, & Davenport, 2013). Contributing operations included sites from the USA and Mexico (9), Chile and Peru (6), Laos (1), Kazakhstan (1), and Africa (9). Despite fewer contributions compared with past experience, this survey nevertheless represents 2018 copper EW cathode production of 1.76 Mt, or about 38% of world production of 4.64 Mt (International Copper Study Group, 2017). This drop in permission to contribute is attributed to the more competitive nature of the industry and unprecedented production pressures; furthermore, several operations in Australia have shut down, while large operations that are currently commissioning or ramping up to full production in Africa and Asia declined to participate. Of the Chinese operations, which represent an increasingly important proportion of global electrowon cathode copper, particularly in Africa, only Tenke Fungurume (Democratic Republic of Congo; DRC) participated in this survey.

Jan 1, 2019

By S. Avalos, J. M. Ortiz, W. Kracht

Semi-autogenous grinding mills are intensive energy consumers. Current models base their energy consumption inference on operational variables and feeding ore characterization. While they provide adequate design guidelines, they are not suitable for real-time energy forecasting dealing with gaps in operational dataset and up/downstream process bottlenecks. This work explores the capability of Gated Recurrent Units to learn the semi-autogenous grinding mill consumption behaviour. Gated Recurrent Units are trained to forecast different time-support consumptions under a time-series operational dataset. The results show high performance on small supports (30 minutes) to capture local variability and long-trends while larger time supports (8 hours) can only capture time-trends but not local variability. The proposed technique seems promising for further research and implementation on real mine cases since the input variables are low-cost and easy to obtain. INTRODUCTION Current changes in the Chilean energy matrix (Román-Collado, Ordoñez, & Mundaca, 2018), from fossil fuels to renewable energies, have impacted different industries and particularly the mining sector. Solar energy incorporation into greenfield/brownfield projects will help reducing costs and will lead to rethink foundational paradigms (production and processing strategies) (Pamparana et al., 2017). Also, integration of new space-time predicting tools together with automated real-time updating models are some of the main challenges in the geometallurgical framework (Ortiz et al., 2015; van den Boogaart & Tolosana-Delgado, 2018). Those contexts encourage and demand the development of tools capable of predicting the energy consumed by mining systems, being comminution the greatest energy consumer with an average close to 50% of the entire mine consumption (Cochilco, 2013). In comminution, the semi-autogenous grinding mill (SAG) represents the largest energy consumer (~10 nominal each SAG). Theoretical and empirical energy consumption models (Jnr & Morrell, 1995; Morrell, 2004; Silva & Casali, 2015) base their inferences mainly on feed/product size distributions, SAG sizing, bearing pressure, feed hardness, water addition and grinding charge level, and commonly assume steady-state and work isolated from up and downstream processes. While those techniques provide adequate design guidelines, they are not suitable to predict hourly, daily or even weekly energy consumptions on interconnected comminution circuits where upstream/downstream bottlenecks lead SAGs to operate below designed regimes. Forecasting energy consumption is required by short-term energy management, medium and long-term planning energy consumption, designing the nominal capacity of renewable energy sources, among other. Also, when models are input-sensitive and some of those input measurements are expensive and/or time consuming, model robustness suffers when real-time predictions are required.

Jan 1, 2019

By S. Timbillah, R. LaDouceur, C. A. Young

A low carbon-chain trithiocarbonate ((NaOOC)CH2SCSSNa), known as Orfom® D8, was tested as an organic depressant in the differential flotation separation of chalcopyrite and molybdenite in the presence of sodium isopropyl xanthate (SIPX) or potassium ethyl xanthate (KEX). Flotation studies show that Orfom® D8 depressed chalcopyrite while molybdenite remained floatable. A study of the mechanism of adsorption indicated that Orfom® D8 adsorbs on chalcopyrite through its trithiol (CS -) functional group via both chemisorption and Orfom® D8-metal complexation. The Orfom® D8 depressant is selective and does not form any Orfom® D8-molybdenite bonds. Thus, the combination of the depressant in the presence of either collectors depressed the chalcopyrite and floated the molybdenite. Fundamental parameters of the Orfom® D8 including pKa determination as well as possible decomposition products of the depressant are reported. This study includes an economic case illustrating why using Orfom® D8 can be beneficial. INTRODUCTION Depressants are incorporated in mineral flotation units in the minerals processing industry to make or keep certain minerals selectively hydrophilic. Most reagents used are inorganic and include, for instance, sodium hydrosulphide (NaHS) which is the major reagent used for depressing sulphide minerals, particularly those containing copper, iron and lead. However, the issues with its use include high toxicity, tendency to explode, strong odour, and high consumption due to required high dosages as well as its tendency to oxidise in air. The latter can be overcome by conducting flotation in inert atmosphere such as nitrogen and recycling of the flotation process water. The use of more novel depressants that are essentially organic including homopolar reagents with hydrophilic functional groups on both ends of its structure adsorb onto a target mineral surface with one polar end, the other polar end orients into the bulk solution making the surface hydrophilic and thus, ensuring that the desired mineral does not float. The stringent environmental and safety regulations being implemented in recent times mean that the search for more environmentally friendly chemical reagents is a must have. The use of organic depressants for flotation systems such as Cu-Mo sulfide bulk concentrates has become increasingly important because of the health, safety and environmental issues surrounding the use of inorganic depressants. Nagaraj et al. (1983) investigated the Cu-Mo sulphide flotation system using a structure-activity study of depressants. They found that a major advantage of organic depressants is the ability to tailor-make organic molecules to suit many requirements and thus, eliminate the guess work approach that was predominant in the industry.

Jan 1, 2019

By Li Qihou, Liu Zhihong, Liu Zhiyong, Yao Wei

Black copper sludge, which mainly contains copper, arsenic and a little antimony, bismuth, selenium, tellurium, is an important recyclable secondary resource. In this paper, selective removal of arsenic from black copper sludge by alkaline oxidative pressure leaching was studied. The influences of alkali concentration, leaching time, leaching temperature, oxygen pressure, liquid-solid ratio and other variables on the leaching rate of arsenic, copper and tellurium were investigated. The results were as follows: when the leaching process was conducted at initial alkali concentration of 1mol/L, liquid-solid ratio of 10, stirring rate of 500r/min, leaching temperature of 140°C for 5 h and oxygen pressure of 2.5MPa, the leaching rates of arsenic and tellurium were 85.43% and 59.7% respectively, and copper, antimony, bismuth were not leached. Hence, arsenic has been removed effectively from black copper sludge, while the valuable metals such as copper, antimony and bismuth remained in the residue that can be further recovered easily. INTRODUCTION Black copper sludge is a byproduct in the purification process of copper electrolyte. Arsenic, antimony and bismuth are major harmful impurities in copper electrolytic refining system. The accumulation of these impurities will cause adverse effects, such as the increase of electrolyte resistance and power consumption and deterioration of cathode copper quality (Wang, Liu, & Zhang, 2001). Hence, electrolyte purification is an essential part of the electrolysis process (Liang, Chen, & Guo, 2009). Electrolyte purification methods include electrowinning (Davenport, King, Schlesinger, & Biswas, 2002), solvent extraction (Navarro, Simpson, & Alguacil, 1999), ion exchange (Arroyo et al., 2017), coprecipitation (Wang et al., 2003, 2018; Xiao et al., 2007; Xiao, Cao, Mao, Shen, & Ren, 2014), activated carbon adsorption (Navarro & Alguacil, 2002), electrodialysis (Cifuentes et al., 2015), redox process (Zhou, Peng, Zheng, Ma, & Cui, 2011; Peng, Zheng, Zhou, & Chen, 2012; Zheng, Peng, Ke, & Chen, 2013), among which the electrowinning method is simple in operation and effective in impurities removal, making it the main process for current electrolyte purification. Some copper ions can react with harmful impurities to form complex black copper sludge by controlling the operation conditions of electrowinning process. Based on the estimated data provide by Davenport et al. (2002), an annual output of 400,000 tons cathode copper could produce 432-2168 tons of black copper sludge by electrowinning method. Black copper sludge contains 30~50% copper, 15~30% arsenic and a small amount of rare elements such as selenium and tellurium. Thus, recovery of valuable metals can bring huge economic interests. Moreover, arsenic in these sludges could cause significant environmental pollution. Therefore, effective removal of arsenic from these sludges is urgent and significant.

Jan 1, 2019

By X. J. Guo, H. X. Li

The biological heap leaching at Zijin copper mine is currently the largest industrial application of biohydrometallurgy and one of the earliest mines to develop biological metallurgy technology in China. Since 2001, through demonstration plant and different expansion stages, it has been developed to produce 20,000 tons cathode copper annually. However the ore grade of heap leaching gradually decline year by year with copper grade average at around 0.23% now. The copper mineral is mainly the secondary copper sulfide, and symbiosis with higher content pyrite, the sulfur and iron contents is about 15 times as copper in the ore (S/Cu>15), so the acid and iron treatment of leachate, extractant and acid mine waste water is a great challenge. Combined with located in the rainy area of southern China, huge amounts of over 10 million cubic meters acid drainage need to be treated every year, so the recovery of copper from waste water as well as low grade ore is one of the characteristics of this process. This paper in general introduced the operation of heap leaching, solvent extraction, stripping and electrowinning process in Zijin mine, summarized the experience of production and technical practice, and discussed the methods of heap construction, leaching rate enhancement, third phase formation and treatment, mine effluent treatment, resource recovery and heap slope reclamation. INTRODUCTION The Zijinshan gold and copper mine is located in southeast China, Fujian province, and the typical distribution characteristics of gold and copper deposit are "upper gold and lower copper", both are large porphyry deposits. By the end of 2017, the accumulated proven reserves of available gold resources were 318 tons, copper are 2.15 million tons, and the prospective reserves of copper are more than 5 million tons. The gold mining is open pit while the copper mining is open pit and underground. The cut-off grade of gold mining is 0.15 g/t, and that of copper mining is 0.15%. A large number of very low-grade gold ores (grade <0.30 g/t) adopt a combined ore-dressing process of “partial crushing/ore washing/reprocessing/heap leaching (overlying)/ carbon slurry" independently developed, while flotation and bio-heap leaching are adopted for copper mine. Among them, copper ore with more than 0.25% copper content enters the flotation system to produce copper concentrate, while that of less than 0.25% copper content is processed by bio-heap leaching, solvent extraction and electrowinning. Zijin biological heap leaching plant is the first mine in China to achieve the scale of annual output of ten thousand tons of cathode copper since 2006. In 2008, the solvent extraction and electrowinning system were expanded, now with a daily processing capacity of 20,000 tons of ores, an annual output of 20,000 tons of cathode copper, the expanded plant is the largest biohydrometallurgy plant in China.

Jan 1, 2019

By K. Parameswaran

This paper builds on presentations made at the Conference of Metallurgists (COM) 2015, COM 2017 and Extraction 2018 and associated papers published in the respective conference proceedings. Based on the classic Brundtland Commission definition of sustainable development as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper describes how metal mining can be compatible with sustainable development and how sustainability considerations have been applied in the primary copper industry, using several examples of sustainable mining practices from ASARCO LLC operations. Finally, the paper discusses how these considerations might be used in the future by discussing the need for developing a sustainable development strategy and how this strategy can be aligned with the United Nations Sustainable Development Goals. INTRODUCTION The primary copper industry comprises: mining (also referred to as “extraction”); mineral processing (also referred to as “beneficiation, “milling” or “concentration,”) which includes leaching, solvent extraction (SX), crushing, grinding, froth and flotation operations; and metallurgical processing which includes smelting and converting; refining, which includes fire-refining or anode refining and electro-refining; and electrowinning (EW). There are two routes for producing refined copper: hydrometallurgical and pyrometallurgical. The hydrometallurgical route comprises mining (open-pit and underground), mineral processing (crushing and grinding — for heap leaching only; leaching and SX) and metallurgical processing (EW). The pyrometallurgical route involves mining, mineral processing (crushing, grinding and froth flotation) and metallurgical processing (smelting, fire refining and electro- refining). The primary copper industry is capital, water, resource and energy intensive with the potential for significant environmental impacts, if the environmental aspects are not properly managed. ASARCO LLC (Asarco) was organized in 1899 as the American Smelting And Refining Company. Originally a consolidation of several lead-silver smelting companies, it evolved over the years into an integrated producer of primary non-ferrous metals, including copper, lead and zinc and associated co-products. Grupo México, S.A.B. de C.V (Grupo México) acquired Asarco in 1999. Today, Asarco is a vertically integrated producer of primary refined copper and associated co-products such as gold, silver, selenium and tellurium. Asarco operates three open-pit mines and mills, two leach, SX-EW plants, a copper smelter in Arizona and a copper electrolytic refinery in Texas.

Jan 1, 2019

By Atsuki Sado, Akira Ueno, Kazuaki Takebayashi, Kunio Watanabe

The Saganoseki Refinery of Pan Pacific Copper Co., Ltd., Japan, introduced the ISA 2000® process in 2006 to improve product quality and productivity. After resolving various technical difficulties associated with the process, a current density of 325 A/m2 and electrolytic copper production of 234 000 tons per year were realized in 2018. In recent years, Saganoseki Smelter & Refinery has promoted treatment of recycled materials in addition to copper concentrates. Accordingly, the amount and type of impurities charged to the smelting process have tended to increase. In the electrorefining process, impurities such as nickel and antimony cause anodic passivation and formation of suspended solids, respectively. Although these undesirable phenomena can be avoided by controlling impurity concentrations in the anode and electrolyte to appropriate ranges, this also limits the choice of recycled materials that can be processed by the smelter. To achieve both stable operation of the electrorefining process and flexibility in treatment of recycled materials in the smelting process, Saganoseki Refinery improved the capacity of the impurity recovery processes during 2016 to 2018. This paper describes the expansion of the purification plant to remove and recover nickel and antimony. INTRODUCTION The Saganoseki Refinery of Pan Pacific Copper Co., Ltd., Japan, introduced the ISA 2000® (wax- less permanent cathode method) in 2006 to improve product quality and productivity. Since then, the refinery has gradually increased current density, and has been committed to establishing stable operation and high productivity via various improvements related to the electrolyte filtration and additive management systems. Figure 1 shows the trends of current density and current efficiency at the refinery. Although the current efficiency temporarily dropped when the current density was raised to 322 A/m2, it consistently exceeded 97% thereafter. At present, stable operation at 325 A/m2 has been achieved and continues.

Jan 1, 2019

By A. Malfliet, A. Van den Bulck, D. Willems, M. Guo

The feed stock of copper fire refining processes consists of two major constituents: blister copper and high-Cu secondary scrap. A large fraction of this secondary scrap, originating from urban mining, is quite high in impurities such as Fe, Ni, Pb and Sn. Problems arise in electro-refining when these elements exceed certain limits. As a consequence, transformation of the secondary copper raw materials into high grade copper has become troublesome. However, the behavior of impurities relevant to fire refining conditions, essential for anode refineries, has not been studied in detail. Furthermore, limited research has been performed on the distribution of Ni between copper metal and slag. In this study, equilibration at 1300°C of liquid Cu-1wt.% Ni alloy and CaO-CuOx- FeOy-SiO2 slag in vacuum sealed quartz ampoules was performed for 12 hours, followed by water quenching. Electron Probe X-ray Microanalysis was employed to investigate the composition of the equilibrated alloy and slag. The distribution coefficients of Ni between slag and alloy were determined as a function of oxygen partial pressure and CaO concentration. INTRODUCTION Europe’s initiatives for a circular economy, pushing for resource-efficient ways for a sustainable future, puts Europe at the forefront of the globe. In Europe, 50% of the copper originates from recycling, being an excellent example of Europe’s circular economy (Juncker, 2018; Lacasse, 2018). High-grade copper recyclates are made available which regularly contain impurities like Fe, Ni, Sn and Pb. Aurubis Belgium is responsible for recycling these types of recyclates to anodes, cathodes and copper products. However, after fire refining of copper, the aforementioned impurities remain in the anode copper, leading to problems in electrorefining. During the fire refining of copper, a CaO-“Cu2O”-“Fe2O3”-SiO2 slag is used. Fundamental information of the distribution of impurities between the copper and this slag system is therefore essential to understand and improve the copper fire refining process at Aurubis Belgium.

Jan 1, 2019

By M. Hardy

"The structural design of mine headframes is challenging due to the significant differences in the geometry, rigidity, and behaviour of these structures compared to conventional buildings. The differences are related to the main purpose of these structures, which is not human occupancy, but rather the support of hoisting equipment. The main objective of this paper is to present the seismic elastic behaviour of headframe structures in comparison with conventional buildings, which is the base case for the definition of seismic loads. This paper highlights the impact of backlegs on the dynamic behaviour of mine headframes, more specifically the resulting torsional sensitivity. INTRODUCTION The design of industrial structures is often governed by industrial processes rather than by architectural constraints. In ground-mounted hoisting plants, the structural configuration of headframes must allow clearances around conveyances and ropes while resisting the lateral loads associated with the hoisting equipment. Typically, these structures use backlegs to withstand the lateral loads, which leads to highly irregular structures with unconventional dynamic behaviour. The codes and standards applicable to the structural design of mine headframes in Canada are often incomplete or not adapted to the reality of practising engineers. This situation creates confusion, and engineers must look at various guidelines and international standards to support the engineering calculations required for the design of these structures. The loads resulting from the support of hoisting equipment, such as ropes and conveyances, are usually simple to calculate and are determined based on the information from manufacturer and industry related guidelines. Moreover, the loads associated with snow accumulation and wind are calculated applying the same methodology used for conventional buildings, without any major issues. On the other hand, the seismic loads are often difficult to calculate based on the methodology from the National Building Code of Canada due to the significant differences in the dynamic behaviour of the structures. The resulting structures may be either over-designed or worse, under-designed. Hence, there is a lack of uniformity in engineers’ designs. The latest edition of CSA S16-14 “Design of steel structures” includes Annex M (Informative) “Seismic design of industrial steel structures” to help designers close the gap between the requirements of traditional regulations and actual engineering practice."

Jan 1, 2019

By Tim Robinson, Michael S. Moats, William G. Davenport, Andreas Filzwieser, Andreas Siegmund, Shijie Wang

This survey continues the long tradition of providing a snapshot of operating data from industrial electrorefineries. It is a supplement to previous surveys that were performed in 1987, 1991, 1995, 1999, 2001, 2003, 2007, 2010, 2013 and 2016. Analyses of current data and historical trends are presented. Examples of innovations to reduce costs, improve productivity, and improve quality are provided. In general, refineries continue to increase productivity while treating anodes with more impurities. INTRODUCTION This manuscript analyzes global survey data provided by operating copper electrorefineries. This paper continues a series of surveys of copper refining tankhouses that started in 1987 (Schloen, 1987, 1991; Schloen & Davemport, 1995; Davenport et al., 1999; Robinson et al., 2003; Moats et al., 2007, 2013, 2016). In this installment, data collected from 2015 and 2018 will be presented and analyzed. The 2015 survey data were presented at Copper 2016 in Kobe, Japan. This survey will continue the analysis of previous data to illustrate long term trends in copper electrorefining, which were originally presented at the Davenport Symposium in October, 2014 (Moats, Robinson, & Wang, 2014). Refineries who supplied surveys are listed in Table 1. Cathode production data from 2015 and 2017/18 (from surveys presented in 2016 and 2019) are provided to indicate which plants provided surveys and when. This manuscript presents operating data for ~6.5 million tonnes of copper production, which represents 30–35% of the world’s copper electrorefining production. The detailed survey results are available upon request from the corresponding author.

Jan 1, 2019

By L. Vollert

In August 2018, the first full-scale HydroFloatTM cells for the recovery of coarse composited copper and gold were commissioned at Newcrest’s Cadia Valley operation in New South Wales, Australia. The primary objective of the installation is to recover coarse value-bearing composites that are lost to conventional flotation tailings, without the need for additional power input for particle size reduction to improve mineral liberation. This paper examines the application of Eriez HydroFloatTM technology for the recovery of coarse, poorly liberated copper sulphide particles drawing on recent experience from lab scale testwork through circuit design and commissioning of the full-scale installation at Cadia Valley. INTRODUCTION In the face of declining copper head grades and a tightening regulatory environment around the use of wet tailings dams, the processing of copper ores at coarser particle sizes has become a focal point for the industry. Sulphide flotation using the Eriez HydroFloatTM is one of the emergent technologies that sits under this umbrella of coarse pre-concentration. It has been demonstrated through numerous lab and pilot scale testwork programs carried out by Newcrest and others (Awatey, Kohmuench, Thanasekaran, Skinner & Zanin, 2013), to improve the flotation recovery of sulphide-rock composite particles with low surface liberation, relative to conventional flotation technology. The HydroFloatTM technology has been used widely for the recovery of coarse potash, phosphate, coal, vermiculite, spodumene and diamonds but has never been applied at full scale in either gold or sulphide flotation. In August 2018, the first full-scale 3.4 m diameter HydroFloatTM cells for the recovery of coarse composite copper and gold were commissioned at Newcrest’s Cadia Valley operation in New South Wales. The primary objective of the installation is to recover coarse value-bearing composite particles that are lost to conventional flotation tailings, without the need for additional upfront power input for particle size reduction to improve mineral liberation.

Jan 1, 2019

By V. Vekris

A diverse patent portfolio and an effective intellectual property strategy are vital in today’s small business world. Not only does a diverse patent portfolio enable a company to secure a monopoly within the market, it greatly increases the value of a company’s intangible assets and keeps competitors at bay. An overview of the patenting process as it pertains specifically to the materials science-related start-ups will be given, together with a summary of some general patenting strategies and a review of some patenting errors to be avoided, such as premature disclosure of the invention to the public. Additionally, a review of new “green technology” initiatives recently adopted by Patent Offices around the world is also provided. These initiatives are expected to greatly benefit patent applicants in the fields of metallurgy and mining, where research efforts are often directed to environmentally-friendly products and processes. INTRODUCTION Patents are playing an increasingly significant role in the business world. A diverse patent portfolio can enable a company to secure a monopoly within the market, which can provide a competitive advantage over competitors. At the same time, patent portfolio of any size can greatly contribute to the total value of a company’s intangible assets. As an example, Nortel entertained bids in 2011 for its portfolio of about 4000 patents, a large portion of which were directed to 3G- and 4G-mobile communication technologies. The portfolio was eventually sold for $4.5 billion to a consortium including Apple, EMC, Ericsson, Microsoft, Research in Motion, and Sony. Copper mining, and indeed the global mining industry as a whole, is facing challenges. Ore deposits are increasingly low grade, complex, and deeper in the ground, rendering copper mining operations more difficult and costly. Production costs are increasing. According to one study, the cost of producing copper has increased by an average of 10% per year since 2005 (Cantallopts, 2017). To illustrate, the cost of producing a pound of copper in 2005 was 90 cents, but had increased to 217 cents by 2014.

Jan 1, 2019

By N. Molaei, E. R. Bobicki

The continued demand for mineral products, coupled with the depletion of high-grade ore resources, has led to the mining of lower grade ores, which often require fine grinding to achieve mineral liberation. Regrinding of low-grade ores results in the production of fine gangue mineral solids and produces vast quantities of fluid fine tailings which are difficult to separate from water, particularly if they are composed of clay minerals. Organic synthetic polymers and inorganic salts have been widely applied in flocculation of colloidal suspensions in the treatment of mining tailings. However, there are growing concerns regarding their impact on the environment and human health. Recently, extracellular biopolymer flocculants or bioflocculants have attracted much attention as alternative reagents. In this study, much effort has been devoted to considering the effectiveness of protein and polysaccharide-based biopolymers for the dewatering of clay slurries. The interaction between kaolinite and illite clays and biopolymers was investigated via settling tests at pH 7 and 10. Zeta potential measurements were also conducted as a complementary technique. Results showed that protamine and lysozyme protein- based biopolymers were generally the more effective bioflocculants. Pectin, a polysaccharide-based biopolymer, showed a dispersing effect and has the potential to be used as a dispersant and/or depressant for clay minerals in froth flotation. INTRODUCTION With the depletion of high-grade ore resources, the need for mining of low-grade ores has increased over the past few decades (Bourgès-Gastaud, Stoltz, Dolez, Blond, & Touze-Foltz, 2014; Chen, Walshe, Fru, Ciborowski, & Weisener, 2013; C. Wang, Harbottle, Liu, & Xu, 2014). Low-grade ores often require fine grinding and contain clay minerals, leading to the generation of fluid fine tailings (FFT). It is a challenging process to separate suspended clay particles from water (Craciun, Manaila, & Stelescu, 2013; Dompierre, Lindsay, Cruz-Hernández, & Halferdahl, 2016; Kasperski & Mikula, 2011; Mercier et al., 2012). Clay minerals form stable dispersions in water due to their anisotropic nature, non-spherical morphology and colloidal size (Lagaly & Ziesmer, 2003; Olphen, 1977). The difficulty in separating clay minerals from water has led to the accumulation of vast quantities of FFT in oil sands, phosphate, copper and nickel operations, representing a huge liability for mining companies (Chen et al., 2013; Mercier et al., 2012)

Jan 1, 2019

By A. Lewis, J. Zachwieja, M. Widell, P. Zhou, W. W. Geissler, M. Svensson, A. Movahedi, H. Nordberg

Flotation collectors for sulfide minerals has been traditionally based on xanthate, thiophosphate, thiophosphinate and thiocarbamate, all derived from sulfur chemistry. Tecflote™ is a new family of patented collectors based on nitrile chemistry which can supplement or replace thiol collectors, depending on the ore types. A steep grade-recovery curve typical of Tecflote™ collectors was observed when using Tecflote™ as the main collector for the rougher and cleaner steps allowing a better recovery compared to current thiol collectors while maintaining the desired grade. Additional recovery increase has also been observed by the addition of scavenger steps using Tecflote™ collector in combination with current thiol-based collector. The selectivity seen in the lab is transferred to full scale trial and is clearly seen in the rough flotation where the increase in the rough concentrate grade of 5% after pumping Tecflote S11 directly into the tank cell. The mechanisms for Tecflote’s selectivity towards sulfides are currently under investigation and will be discussed. Results of TOF-SIMS analysis will be presented, demonstrating the collector’s selective affinity to different mineral surfaces in flotation. INTRODUCTION The history of collectors used today started in 1882 when Zeise first made xanthates. It was first used in flotation in 1925 – Cornelius Keller’s first patent (Fuerstenau, Jameson, Yoon, 2007). Between 1928 and 1930 American Cyanamid filed 7 patents for dithiophosphate, including flotation and chemical synthesis of the reagent, the first of which was filed by Christmann in 1928 (Christmann, 1933). Synthesize of thionocarbamates for mineral flotation was filed in 1954, by Dow Chemical Company (Harris, 1954). Now that the head grades have been declining over the last decades the need to find more selective collectors to extract difficult and complex ores has pushed the industry to look at different chemistries. Thiol collectors standard to the industry rely on the sulfur in the collector molecule to bond to the mineral surface. The electronic property of this group is modified by the adjacent chemical groups, such as additional S, P or N have the effect of changing the selectivity of the collector (Wills & Finch, 2016). In the case of xanthate the length of the hydrophobic group also has an effect on the selectivity with some minerals such that the ethyl xanthate is more selective against pyrite and pyrrhotite than the long chain xanthates (Wills & Finch, 2016).

Jan 1, 2019

By D. Sancho, M. Weber

"At the start of a new shaft project, a specific number of ground investigations are performed. However, it is not uncommon that the ground conditions during shaft sinking may differ from the designed ones. Therefore, it is extremely important to use tools which minimize discrepancies and to include a monitoring system in the shaft design to collect sufficient data. The paper presents an overview of existing monitoring techniques and discusses future works required to improve, not only the construction during shaft sinking, but also the lining design methodology. INTRODUCTION In most cases, the investigations performed at the start of a new shaft are based on the analysis of rock and soil probes obtained from boreholes. In practice, such analysis performed on a single core often leads to different results when conducted by various experts. The discrepancy in core analysis influences further rock mass assessment and design assumptions. It is not uncommon that the ground conditions during shaft sinking may differ from the designed ones, which affects the estimated stress and strain state of the shaft lining. Therefore, it is extremely important to use tools which minimize such discrepancy and to include into the shaft design a monitoring system to collect sufficient data, which enables control of important phenomena, not only during shaft sinking but also during the life of the shaft. Furthermore, the information collected during shaft sinking, while it is important for proper shaft lining design and updates to the shaft lining due to the local mining and geological conditions, it is also important after shaft sinking. In the whole shaft lifetime, it is not uncommon that the shaft lining is damaged and the liner needs to be renewed (Figure 1) due to various reasons. For this purpose, detailed information collected during construction can be extremely important."

Jan 1, 2019

By N. A. Beier, R. Amos, Smith. L., C. Atherton, D. R. Barsi, D. Blowes, D. C. Sego

"Waste rock is one of the most abundant materials at mine sites and must be properly characterized and managed to limit acid rock drainage and other harmful byproducts. An experimental waste rock pile—part of the test piles research program—located at the Diavik diamond mine (Northwest Territories, Canada) was deconstructed and sampled to study the spatial variability of material properties. Bulk samples were classified based on the amount of material finer than 4.75 mm. Hydraulic properties of each sample were estimated and particle size distribution analysis was completed. These datasets and classification methods might be used to improve the understanding of hydraulic and geochemical behaviour of the material and to study waste rock at other sites. ¦ KEYWORDS Acid rock drainage (ARD), Material classification, Particle size distribution (PSD), Waste rock RÉSUMÉ Les stériles font partie des matériaux les plus abondants sur les sites miniers et, en tant que tels, doivent être correctement caractérisés et gérés afin de limiter le drainage rocheux acide (DRA) et la pré¬sence d’autres sous-produits nocifs. Dans le cadre du programme Test Piles Research Program, un amas de roches stériles expérimental situé à la mine de diamant Diavik (Territoires du Nord-Ouest, Canada) a été décomposé et mis à l’essai afin d’étudier la variabilité spatiale des propriétés des matériaux. Les échan¬tillons en vrac ont été classés en fonction de la quantité de matériaux plus fins que 4,75 mm. Les propriétés hydrauliques de chaque échantillon ont été estimées et l’analyse de la composition granulométrique effectuée. Ces ensembles de données et méthodes de classement serviront à mieux comprendre le com¬portement hydraulique et géochimique du matériau et à étudier les stériles sur d’autres sites. ¦ MOTS CLÉS classement des matériaux, composition granulométrique, drainage rocheux acide (DRA), stérilesINTRODUCTION Statement of problem The characterization of mine waste rock remains a challenge in active mining sites. The large volume of material and the large size of particles make it difficult to collect representative samples. Sampling techniques are often dis-ruptive to mining operations because they alter the structure of the waste rock pile or interfere with mine traffic. The convention at most mine sites to collect little to no information on waste rock material means that models and predictions of how waste material will behave and interact with the surrounding environment are based on general information that might not be site specific. This could lead to environmental damage or higher costs if environmental effects are underestimated during the construction of waste rock structures."

Jan 1, 2019