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By Bahri Öteyaka, Ali Uçar, Oktay Sahbaz

"A Jet Diffuser Flotation Column (JDFC) is a newcomer flotation device whose operation principles similar with Jameson cell but it has an essential change in downcomer. By taking into account the hydrodynamic and fluid mechanic principles (Sahbaz et al. 2013) downcomer was changed as a diffuser, therefore turbulence at the end of the downcomer was reduced to provide better aggregate stability and homogenous dissipation of the bubbles in the separation tank. Thus the performance increase has been aimed for the coarse particles.According to theoretical results, obtained by the formula of Oteyaka (1993) showing the relationship between velocity gradient and maximum floatable size for the various contact angles, the d50 of quartz flotation of JFDC is about 240 µm and 310 µm for the contact angle of 50° and 60°, respectively. This result was verified by the experiments. According to the experimental results; d50 which was accepted the maximum floatable particle size of quartz flotation of JFDC was about 256 µm and 300 µm for the contact angle of 50° and 60°, respectively.INTRODUCTIONFlotation is a kinetic process used for separation of hydrophobic particles from hydrophilic particles. There are many different parameters affects the success of the flotation and particle size is one of them. While the flotation is very efficient for intermediate size, the efficiency of the process starts to decrease for both fine and coarse sizes (Trahar, 1981; Muganda et al., 2011). Therefore; researchers have tried to find a solution for the efficiency decrease in fine and coarse sizes by modifying the chemical condition and designing the new devices. For example, Jameson cell is a unique device for the fine particle flotation due to the suitable design and fine bubble producing (Jameson, 1988; Evans et al., 1995; Sahbaz, 2010). Because of this success operation the Jameson cell is applied more than 200 flotation plants in worldwide. On the contrary, the efficiency of the cell decreases for coarse particle flotation due to the turbulence occurred in the separation tank (Sahbaz, 2010; Cowburn et al., 2007). That’s why, new flotation device was designed in loboratory scale by Sahbaz, Oteyaka and Ucar in 2010s and it has been called as Jet Diffuser Flotation Column (JDFC) recently."

Jan 1, 2016

By Chun-Sheng Liao, Chun-Hua Yan, Sheng Wu, Fu-Xiang Cheng

"INTRODUCTIONChina is providing more than 90% of the rare earth products consumed in the whole world. Acidic extractants are commonly used in the extraction separation of rare earths. Saponification of the acidic extractants by basic substances is usually necessary for the purpose of increasing and stabilizing their extraction capacity, and meanwhile inorganic acids are required for both scrubbing and stripping. Thus acids and bases are the main consumed chemicals, and the resulting salts are the main pollutants generated by rare earth separation processes. Currently, due to increasing environmental concerns in China, rare earth solvent extraction separation techniques are being developed to reduce both consumption and emission of chemicals, which is driving the developments on both theories and processes for solvent extraction separations.In the 1970s Prof. Xu et al. developed the Theory of Countercurrent Extraction (Xu, Li, & Yian, 1985). In recent years, the development of novel processes for rare earth separation has moved beyond the earlier theory. One rare earth separation process, the so-called hyperlink process, has been developed in the past decade and proven in industrial practice to dramatically reduce both the consumption and emission of chemicals during multi-component solvent extraction separations, and therefore is now widely used in the Chinese rare earth separation industry (Liao, Wu, Cheng, Wang, Liu, Zhang, & Yan, 2013). The present article will give a brief review of the development of the theory of the hyperlink processes, and the hyperlink separation flowsheets for typical rare earth mines in China designed using the theory.HYPERLINK PROCESSES (LIAO et al., 2013)A flowsheet of multiple-component separation consists of a couple of separation units. The units of a conventional flowsheet separately consume chemicals for saponification and scrubbing and discharge wastewater with resulting salts. In contrast, the separation units in a hyperlink process are hyperlinked and thereby the chemical demands of the whole flowsheet are decreased. For a feed containing t components of A1, A2, …, and At, it has been proved in theory that the separation mode of (AtAt-1…A2)/(At-1At-2…A1) is preferred in a single separation unit. The hyperlinking between separation units can have two forms. The link between two units locating at a same separation level, such as between (A4A3)/(A3A2) and (A3A2)/(A2A1), is known as horizontal hyperlinking. The link between two units located on different levels, such as between (A4A3A2)/(A3A2A1) and (A3A2)/(A2A1), is known as vertical hyperlinking. Both the hyperlinking forms have been proven to save chemical usage and consequently to lower the pollution emissions in industrial practices as well as in theory."

Jan 1, 2016

By Mark W. Masson, David B. Stevenson, David W. Broughton, Douglas R. Cruji, Steven E. Parry

"Abstract-The Amalgamated Kirkland gold deposit is located at Kirkland Lake, Ontario, within the Archean Abitibi Greenstone belt of the Canadian Shield. It lies on a fault or "break", termed the Cyprus Break, which is a splay off a regional structure termed the Cyprus-Battle Mountain Break. The Cyprus Break merges with the Cyprus - Battle Mountain Break above the -250 m level, as it was not encountered in shallow drilling or surface exploration. These structures lie 1.5 km south of the 727 000 kg (23 million ounce) Kirkland Lake Main Break and 0.5 km north of the 872 000 kg (30 million ounce) Larder Lake Break.The deposit is hosted by alkalic Timiskaming Group volcanic and sedimentary rocks which are overthrust by older Larder Lake Group tholeiitic and komatiitic flows along the Larder Lake Break. Timiskaming syenitic intrusives, similar to the host rocks for the Kirkland Lake Main Break gold deposit, intrude both suites.The Amalgamated Kirkland deposit consists of lode-style gold mineralization which is mainly hosted by altered and pyritized Timiskaming trachytic volcanics which wedge out or thin at depth, between two sedimentary units. The intersection of the Cyprus - Battle Mountain and Cyprus Breaks, in conjunction with the westward plunge of the volcanic wedge, appears to control the westerly plunge of the Amalgamated Kirkland deposit at approximately 50º.Mineralization is characterized by blue-gray brecciated and "wormy" quartz-ankerite veins which contain up to 10% fine-grained pyrite and, in decreasing order of abundance, minor galena, chalcopyrite, sphalerite, molybdenite and visible gold. The sulfides and gold commonly occur along fractures and wallrock inclusions within the veins. Native gold occurs as fine pinpoints distributed in 1-mm to 5-mm size clusters of up to ten or more grains.The auriferous veins occur within a quartz-ankerite-sericite-pyrite alteration assemblage which is enveloped by a broader zone of ankerite-sericite±hematite±quartz-pyrite alteration up to 60 m wide. This latter assemblage overprints the regional greenschist-facies chlorite-calcite assemblage.The Amalgamated Kirkland property has had a long history of exploration activity beginning with the first discovery of mineralization in 1911 on the Hunton Shaft claim located in the northeast corner of the property. Since that time various prospecting, mapping, trenching, geophysical surveys and diamond drilling programs have concentrated on either carbonate zones along the Larder Lake Break or quartz veins along the northern side of the property in association with complex trachyte flows and syenite dikes.Battle Mountain Canada Inc. located the Cyprus - Battle Mountain Break through a prospecting, trenching and geophysical program in 1989. Drilling by Battle Mountain and Cyprus Canada under the surface showing, coupled with several revisions to the structural interpretation of the Cyprus - Battle Mountain and Cyprus Breaks, resulted in delineation of the Amalgamated Kirkland deposit. Location of an auriferous structure through basic surface exploration within 1 km of a world-class orebody demonstrates both the subtle nature of Archean gold deposits and the potential for finding new mineralization in heavily prospected camps."

Jan 1, 1995

By Y. M. Shneerson, I. V. Fomenko, M. A. Pleshkov, E. A. Ospanov, A. A. Shakhalov, S. S. Naboychenko

Low-grade copper concentrates (with copper content less than 20%) often contain impurities such as arsenic, zinc, lead, mercury, antimony and bismuth. The pyrometallurgical treatment of such concentrates is associated with several problems, which will ultimately affect the cost and the quality of copper cathodes as well as by-products. SRC Hydrometallurgy proposed a complex hydrometallurgical technology which allows the removal of impurities and the enrichment of low-grade copper concentrates to a quality which will be more suitable for pyrometallurgical processing. Laboratory batch tests and pilot plant results for the pressure leaching steps are shown in this paper. The key parameters of the leaching steps were determined and optimized. The quality of possible by-products were also determined. The developed flowsheet includes two pressure leaching steps: pressure oxidation (POX) and hydrothermal alteration (HTA). Both operations are carried out at 170°C with subsequent flotation of POX and HTA residues and recovery of copper, zinc and lead into separate concentrates for further processing. The development of the flowsheet was based on the Balkhash Zinc Plant (Balkhash, Kazakhstan), which had been non-operational since 2009. The developed flowsheet for processing of low-grade concentrates will utilize 80% of the existing equipment of the Balkhash Zinc Plant, thus leading to a significant reduction in required capital expenditure. INTRODUCTION As the age of copper mining operations advance, copper grades continue to diminish and impurity levels increase. Therefore, copper producers are forced to look for new innovative hydrometallurgical technologies which are able to handle low-grade raw materials and solve problems associated with impurities in an economically justifiable way. New technologies allow to extract valuable components selectively and to process low-grade concentrates which had previously been marked as non-technological and economically unviable. Hydrometallurgical technologies for processing of copper-containing materials can be divided into two main categories: chloride and sulfate (atmospheric, autoclave and bacterial) based technologies. Since the 1970s, many autoclave techniques for the processing of copper-containing materials have been developed and implemented (Naboichenko, 2002; Dreisinger, 2005; Habashi, 2009; Shneerson, 2011). The mineralogical composition of the ore (or concentrates), geographical location of the deposit, distance from industrial areas, availability of existing treatment facilities, availability of skilled labor, cost of electricity and cost of neutralization are some of the factors which are usually considered when the appropriate technology is selected (Halbe, 2002).

Jan 1, 2019

By G. Armand, A. Noiret, D. Seyedi, J. Morel

"Clay formations in their natural state exhibit very favorable confining conditions for repository of radioactive waste because they generally have a very low hydraulic conductivity, small molecular diffusion and significant retention capacity for radionuclides. Nevertheless, one concern regarding the hydromechanical behavior around drifts in such claystone is the associated pore pressure field disturbance during excavation works. In the short term, the very low permeability leads to an almost “undrained” condition, meaning that the stress change due to face advance will create volumetric strains leading to an increase or decrease of pore pressure. If the effective stresses reach the failure level, the induced damage around these excavations might change the favorable properties of such formations. To demonstrate the feasibility of a reversible deep geological disposal of high-level and intermediate-level long-lived radioactive waste (HLW, IL-LLW) in the Callovo-Oxfordian claystone (COX) formation, the French national radioactive waste management agency (Andra) started in 2000 to build the Meuse Haute-Marne underground research laboratory (M/HM URL). The present paper illustrates observed pore pressure changes during excavation of drifts (˜5 m diameter), of micro tunnels (˜0.7 m diameter) and a borehole (˜0.15 m diameter). All these openings are parallel to the major horizontal stress at the main level of the M/HM URL. In drifts parallel to the major stress (i.e., when the initial stress field in the drift section is quasi-isotropic) an important increase followed by a drop of pore pressure is observed in the horizontal plane at the drift wall. These observations emphasize the impact of the in situ stress state and rate of excavation on the pore pressure and provide important insight of the hydro mechanical behavior of the COX claystone and the relationship between pore pressure and excavation induced fractures zone."

Jan 1, 2015

By P. R. Brito-Parada, G. Bhutani

"The physical processes occurring in flotation columns are very complex as they take place at different scales over a range of sizes and multiple phases. Column design and optimum operating parameters are usually obtained from empirical studies and although progress has been made on its numerical modelling, most column models rely on simplifications that do not fully capture the hydrodynamics. In particular, Computational Fluid Dynamics (CFD) models of the pulp phase in flotation usually assume the bubble population to be monodispersed. While this assumption may be reasonable in some situations, the polydispersed nature of the gas phase can have a significant impact on the predicted flotation rates.Techniques to model size distribution do exist in the literature and have been rigorously analysed in the past two decades for bubble columns, which are very similar to flotation columns from a hydrodynamics point of view. In fact, available CFD models of flotation columns are an extension of bubble column models, sometimes including additional equations for solids treated as passive scalars. This work focuses on the development of an efficient CFD model for flotation columns. The bubble size distribution in the column has been modelled using the Population Balance Equation (PBE), which is solved using the Direct Quadrature Method of Moments (DQMOM). Coupled with the PBE, the multiphase flow equations in the column have been modelled using the standard Eulerian–Eulerian approach. The solution of this coupled system has been made tractable in this work with the implementation of a highly parallelised adaptive-mesh finite element method. This powerful framework has been implemented in the open source CFD code Fluidity and it allows the carrying out of detailed simulations of flotation columns in 2D and 3D, with important implications for industrial column evaluation and design."

Jan 1, 2016

By M. S. Moats

"The effects of commercial copper electrorefining additives (glue and thiourea) on the electrochemical removal of bismuth are of importance in copper production. It was found that Bi(III) electrodeposition occurs readily from acidic sulfate solution via a diffusion-controlled quasi-reversible reduction. The diffusion coefficient of Bi(III) was measured and found to be less than reported values of copper in similar solutions. The presence of thiourea and/or glue was found to accelerate or de-polarize Bi(III) reduction on stainless steel as compared to the inhibition or polarization of Cu(II) reduction. The additives also inhibited the dissolution of the Bi-Cu co-deposit during cyclic voltammetry. During short term deposition studies, the additives increased the concentration of Bi in co-deposited Cu-Bi products from solutions with low concentrations of Cu (<2 g/L). Bi deposition was significantly suppressed by increasing the Cu(II) concentration in the solution. The formation of a copper layer on the stainless steel electrode appeared to significantly suppress the reduction of Bi(III). This study demonstrates that glue and thiourea depolarize the deposition of bismuth on stainless steel. Therefore, the additives could be used to improve Bi impurity removal during third stage liberation.INTRODUCTIONThe production of high purity copper has been steadily increasing due to the wide application of the metal and its alloys in electrical and electronic products, infrastructure construction, industrial machinery and equipment, general products and transportation (Moskalyk et al., 2003). Most high purity copper is manufactured from copper sulfide mineral concentrates and/or scrap via a pyrometallurgical process followed by electrorefining (Navarro et al., 1999). During the electrorefining process, cast anodes of 99-99.5% purity are electrochemically dissolved into an acidified copper sulfate solution while high purity copper (>99.99%) is plated on stainless steel blanks or copper starter sheets (Davenport et al., 2002). The control of cathode deposit growth (purity and morphology) while maintaining a high current efficiency is of significant importance for copper refining (Ilkhchi et al., 2007). At typically applied current densities for industrial copper electrorefining, mass and charge transfer play important roles in the quality of cathodic products (Hiskey et al., 1998). If the real current density at some surface points is substantially higher owing to uneven current distribution, then rough spots can and will grow faster leading to nodules (Suarez et al., 1992). Nodulated deposits tend to capture solution and anode impurities (slimes) resulting in unacceptable cathode quality (Afifi et al., 1987). Furthermore, these nodules can grow until they eventually contact the anode leading to short circuits and current efficiency reduction (Ilkhchi et al. 2007)."

Jan 1, 2016

By M. Coleman, M. E. Reed

The control of feed delivery quality to the flash furnace remains an unsolved problem. Many operations around the world still have limited control of feed quality to their flash furnace. Schenck Process and WorleyParsons continue to work towards the ‘holy grail’ of simple quality feed delivering both radial feed distribution and pulseless feed delivery. Ten years ago they joined forces to offer a system based on then Clyde Process RotoFeed system which could deliver ground level installation, online mixing of materials, pulseless feeding direct to the burner, with good radial distribution. Unfortunately, this proved to be too large a step for the Flash Smelting community and met with resistance from the process owners. Since then the community has developed a range of options some of which have been implemented over this period. Despite these improvements there are still areas of concern including safety issues associated with concentrate leaks and spills, uncontrolled variations in feed rate including massive flooding events, intermittent distribution improvement and set up of the burner continues to be trial and error and hard to repeat the success in each burner campaign. These continue to impact flash furnace performance globally on a daily basis. Following the community reticence to pursue the complete solution a number of interim steps are now available to pave the way to the ultimate feed system. The mixing of material has been installed and is delivering line blended materials on a daily basis. This paper will investigate the developments over the last 10 years and discuss the pros and cons of this incremental step process for overall furnace control. INTRODUCTION Schenck Process and WorleyParsons have continued to interact and observe changes in the flash smelting industry and to consider application of the Clyde RotoFeed now incorporated in the Schenck Process ProStreamTM range for delivery of feed directly to the concentrate or matte burner. Schenck Process pneumatic injection from the Clyde Process range, ProStreamTM, utilises two types of volumetric feeders to accurately control the feed of material into an injection pipeline. These are referred to as the RotoFeed and RotoScrew technologies and the choice of feeder type is dependent on the characteristics of the material to be handled. The RotoFeed is generally used for finer, granular and powdered materials which cannot be accurately handled with a screw such as pulverised coal and copper concentrate, whilst the RotoScrew is particularly suited to coarser lump materials, particularly abrasive of cohesive materials like zinc powder, electronic scrap and metal ashes. Both units can operate at high pressures and many systems work at 3 to 10 bar with the occasional system working at 20 or 30bar for carbon to gasifiers. For the Flash furnace the ProStreamTM units can be used to deliver each of the furnace feed materials into a single line, mixing the materials homogeneously and live to the burner.

Jan 1, 2019

By Mark W. Masson, David B. Stevenson, David W. Broughton, Douglas R. Cruji, Steven E. Parry

"The Amalgamated Kirkland gold deposit is located at Kirkland Lake, Ontario, within the Archean Abitibi Greenstone belt of the Canadian Shield. It lies on a fault or “break”, termed the Cyprus Break, which is a splay off a regional structure termed the Cyprus-Battle Mountain Break. The Cyprus Break merges with the Cyprus – Battle Mountain Break above the -250 m level, as it was not encountered in shallow drilling or surface exploration. These structures lie 1.5 km south of the 727 000 kg (23 million ounce) Kirkland Lake Main Break and 0.5 km north of the 872 000 kg(30 million ounce) Larder Lake Break.The deposit is hosted by alkalic Timiskaming Group volcanic and sedimentary rocks which are overthrust by older Larder Lake Group tholeiitic and komatiitic fows along the Larder Lake Break. Timiskaming syenitic intrusives, similar to the host rocks for the Kirkland Lake Main Break gold deposit, intrude both suites.The Amalgamated Kirkland deposit consists of lode-style gold mineralization which is mainly hosted by altered and pyritized Timiskaming trachytic volcanics which wedge out or thin at depth, between two sedimentary units. The intersection of the Cyprus – Battle Mountain and Cyprus Breaks, in conjunction with the westward plunge of the volcanic wedge, appears to control the westerly plunge of the Amalgamated Kirkland deposit at approximately 50º.Mineralization is characterized by blue-gray brecciated and “wormy” quartz-ankerite veinswhich contain up to 10% fne-grained pyrite and, in decreasing order of abundance, minor galena,chalcopyrite, sphalerite, molybdenite and visible gold. The sulfdes and gold commonly occur alongfractures and wallrock inclusions within the veins. Native gold occurs as fne pinpoints distributed in 1-mm to 5-mm size clusters of up to ten or more grains.The auriferous veins occur within a quartz-ankerite-sericite-pyrite alteration assemblage which is enveloped by a broader zone of ankerite-sericite±hematite±quartz-pyrite alteration up to 60 m wide. This latter assemblage overprints the regional greenschist-facies chlorite-calcite assemblage.The Amalgamated Kirkland property has had a long history of exploration activity beginning with the first discovery of mineralization in 1911 on the Hunton Shaft claim located in the northeast corner of the property. Since that time various prospecting, mapping, trenching, geophysical surveys and diamond drilling programs have concentrated on either carbonate zones along the Larder Lake Break or quartz veins along the northern side of the property in association with complex trachyte flows and syenite dikes.Battle Mountain Canada Inc. located the Cyprus – Battle Mountain Break through a prospecting, trenching and geophysical program in 1989. Drilling by Battle Mountain and Cyprus Canada under the surface showing, coupled with several revisions to the structural interpretation of the Cyprus –Battle Mountain and Cyprus Breaks, resulted in delineation of the Amalgamated Kirkland deposit. Location of an auriferous structure through basic surface exploration within 1 km of a world-class orebody demonstrates both the subtle nature of Archean gold deposits and the potential for finding new mineralization in heavily prospected camps."

Jan 1, 1995

By É. Poulin, J. Bouchard, E. M. Pérez-García

Process control and optimization have always been crucial aspects in the mineral processing industry, and expectations constantly increase to cope with more stringent security, quality, efficiency, and environmental performances. The main challenges to reduce variability of key process variables, and steer profits to higher values while maintaining sustainability indexes within acceptable ranges come from nonlinear responses and circulating loads. The most commonly implemented control strategies rely on simple PID controllers for practical implementation and maintenance considerations. If arguably good performances are accomplished when these are adequately set up, there is also room for further gains by using more advanced methods such as model-based techniques. There is thus a need for more realistic process and equipment models. Based on advances of the past few decades, this paper introduces an autogenous/semi-autogenous mill (AG/SAG) model to be included in a modular comminution circuit simulation toolbox comprising ball/rod mills, material handling, and classification devices. The proposed mill model incorporates a modified version of the classic comminution equation that makes grinding rates proportional to the energy input. It requires the determination of a selection function (fragmentation rates) and a breaking function (fragments distribution). The former is modelled with an S-shaped curve characteristic of AG/SAG processes and the latter is a size-relative distribution of the produced fragments. The power draw is predicted employing the empirical equation of Austin. The paper also develops a case study to illustrate how the proposed simulation framework can capture the behaviour of an actual plant. Model calibration consists in an optimization problem that search the global minimum of the difference between predicted and measured/estimated size distributions, power draw, solid fractions, etc. Results demonstrate that the mill simulator can mimic an actual process in its operation conditions. INTRODUCTION Comminution is a key stage in the mineral processing industry, obviously because the phases of interest must be liberated to be able to recover them. In general terms, the global performance of a plant depends largely on the efficiency of the grinding circuit and on the material properties such as its grindability, density, and mineral grades. The subject has vastly been studied since as early as the 19th century, when Rittinger (1867) and Kick (1883) developed some of the first empirical models to relate grinding and energy input. The great interest in the subject comes from the fact that this operation is costly and, probably most concerning, highly inefficient. Buckingham et al. (2011) estimated that ore comminution can represent up to 60% of the overall plant power draw. Moreover, only a modest fraction of the power draw effectively translates into rock fragmentation. For grinding, estimates range between 1% and 25%, depending on the reference used, while the rest is mainly lost as heath (Fuerstenau & Abouzeid, 2002; Tromans & Meech, 2002; Bouchard et al., 2017).

Jan 1, 2019

By William Petruk, Donald Leroux, Michael Cooper

"Brunswick's primary flotation circuit (CuPb) produces a low grade concentrate containing considerable amounts of undesirable sphalerite and pyrite. To determine the cause of the poor selectivity, a series of Quantitative Mineralogical Analyses (QMA) were performed on several CuPb circuit streams. It was observed that significant fractions of sphalerite and pyrite reporting to the concentrate was liberated, meaning that their depression was not complete. The study highlighted the need for some R&D efforts to be spent in sulphide flotation fundamentals.IntroductionThe viability of many mining projects strongly depends on the performance of their concentrators. More than ever, competitive grade concentrate and high metal recoveries are criteria of paramount economic importance. The selectivity of solid/solid separation processes used in concentrators must be maintained at high levels or continuously improved.Flotation is the solid/solid separation process used by most base metal producers. In spite of its low operating cost, flotation remains a very complex process. To make it selective, precise reagent dosages and electrochemical conditions must be maintained. The difficulty in controlling flotation lies in the numerous heterogeneous reactions that can take place between the different solid, liquid and gaseous phases involved. This complex chemistry makes flotation selectivity difficult to understand and, therefore, to improve from a theoretical point of view.Brunswick Mining and Smelting, near Bathurst N.B., operates a 10500 tpd concentrator which produces four concentrates through five stages of sequential flotation (Figure I). Various reagents are added at key process stages while the ore undergoes different electrochemical conditions. Although the selectivity is important at all stages, the performance of the very first separation, the CuPb circuit, is the most critical. It is here where mineral misplacement to the wrong stream has the greatest economic consequences."

Jan 1, 1996

By Nicolas Gatelier, Sophie Laurent, Thierry You

Hard-rock caverns for hydrocarbon storage are a very particular type of underground facility controlled not only by local administrative and regulatory constraints that can be very specific, but also by the possible risks of geotechnical or geomechanical failure. Each such facility throughout the world is a prototype that needs to be adapted to very different site conditions. The straight forward application of design methodologies from relatively similar fields (mines, tunnels) can be very useful, but risks holding back the scientific and technical improvements needed by an engineering industry in full development. Here we look at various case histories and at problems that have been raised where recent attempts at standardization would appear to have been ill adapted, and where storage designers, through experience and judgment, may still provide innovative engineering solutions.

Jan 1, 2015

By T. Crivits, I. Bellemans, K. Verbeken

In the metallurgical industry, furnace cooling is often employed to enhance furnace lifetime. Hence, the pyrometallurgical phase comes in close contact with a non-air coolant. The proximity of the pyrometallurgical phases to the coolants may lead to dangerous situations. In case of a breach of the cooling circuit, the contact between a hot and a cold liquid may cause a vapour explosion. The outcome of this vapour explosion includes a pressure wave which could result in damage to the furnace, bodily injuries or even casualties. To prevent such dramatic events, the origin of vapour explosions is currently being studied in more detail. For this purpose, OpenFOAM was used to perform Computational Fluid Dynamics (CFD) simulations. In a first step, simulations were run to get a better idea of the influence of the compressibility on the simulations. The obtained results help in getting a better insight on the need of computational power, and possible numerical errors using compressible or incompressible solvers in future simulations. In a second step, systems without vapour explosions were simulated and compared to experimental results with mercury and aluminum. INTRODUCTION Humanity started using metals for tools around the Chalcolitic (~7400 cal BC), when copper was melted in small furnaces (Radivojevic, Rehren, Farid, Pernicka, & Camurcouglu, 2017). Nowadays, metallurgy has grown into a major industry and it has become impossible to imagine society without metals. In the pyrometallurgical industry, coolants (low temperature liquids, for example water) and pyrometallurgical phases (high temperature liquids, such as slags, mattes and alloys) are typically present in close proximity of each other. The interaction between these two phases can have catastrophic consequences (Tveit et al., 2008; Ferguson & Zsamboky, 2017). A vapour explosion may occur as the consequence of the rapid evaporation and expansion of the coolant. Whereas the volume of a gas increases linearly with the temperature (approximately a factor four by heating from 100°C to 1300°C), a simple calculation of the ratio of the two specific volumes shows that evaporation causes the volume of water to increase by a factor of 1700 at 100°C and ambient pressure (Table 1 and equation (1)), a number that was also found in literature (George, Nexhip, George-Kennedy, Foster, & Walton, 2006). The volume change occurs so fast that it resembles an explosion, hence the name vapour explosion. Such an explosion at industrial scale can cause economical losses, bodily injuries or even fatalities.

Jan 1, 2019

By J. Walenzyk

This report investigates the limited use of super large backhoes in surface mines around the world. The demand for super large (> 700 t) hydraulic excavators is rising and most of the machines are sold as front shovel (FS) application. Despite advantages in faster cycle times super large backhoe (BH) machines are a minority (ca. 1% of the total machine population). This investigation is based upon the comparison between the volumes available to the BH and FS in one block and before the machine needs to move. The working conditions are created with standard parameters as given by Original Equipment Manufacturers of hydraulic excavators regarding bench height, angle, and material density. The travel amount of both machine types is derived from these volumes and compared. Furthermore, the travel amount of super large BHs is compared to the travel amount of smaller mining BHs and evaluated based on attachment length and bucket size. The calculations conclude that the volume of material recoverable in a single spot is about 75% higher for FSs. This leads to an increased travel for BHs. The combination of both the increased appearance of electrical driven machines (in the class of > 700 t excavators) and the travel amount lead to a high risk of damaging the cable or the excavator. Enlarged wear on the travelling parts is also attended by the higher travelling. A direct comparison of commonly found working set ups shows that the ratio between volumes is 32% which leads to an increased travel amount. In comparison with a 250 t BH, the calculation shows that the smaller BH is able to reach nearly 50% of the volume of the super large BHs. The main reason for this is the respectively high reach on smaller machines which, combined with other factors, leads to a significantly higher number of BHs in lighter classes.

Aug 1, 2013

By Mariam Melashvili, Chris Fleming, Rene Jackman

"A study was undertaken to develop a flowsheet for treating a high grade silver/gold ore body by cyanidation, CCD and Merrill Crowe precipitation, with tailings detoxification to meet stringent limits for cyanide and thiocyanate concentrations in the final discharge. In one of the flowsheets examined, free cyanide in the final leach liquor was recycled to the mill where it was hoped that it might react beneficially with fresh ore to reduce the cyanide makeup by an equivalent amount. However, laboratory results suggested that most of the cyanide recycled to the mill reacted with iron forming a soluble ferrocyanide complex. This would have had a negative impact on cost, not only because the cyanide recycled to the mill could not be claimed as a credit, but also because the presence of ferrocyanide in the final tailings meant copper sulphate had to be added to the SO2/air cyanide detoxification process to precipitate the iron cyanide. In an alternative flowsheet that was examined, recycling of cyanide to the mill was abandoned, and this allowed the milled slurry to be pre-aerated in a single mixing tank before cyanidation. During alkaline pre-aeration, any ferrous ions that are generated in the mill are oxidized to ferric ions, which, unlike ferrous ions, are inert in cyanide solution. This significantly reduced cyanide consumption and lowered costs in the detoxification of the tailings. In this paper, the cost implication of these two circuits is compared.INTRODUCTIONMost of the gold that is produced by hydrometallurgical processes is recovered by cyanide leaching. The reason for that lies in the superior thermodynamic stability of the gold cyanide complex and the favorable economics this confers on the process (Fleming, 2014). However, the gold in most of the gold-bearing ores processed is a very minor component, and therefore, the leaching response is often dominated by that of the host minerals.Many gold ores treated by the cyanidation process contain iron minerals. Cyanide reacts readily with some iron minerals forming ferrocyanide as one of the compounds. Ferrocyanide is stable when solutions are exposed to air and does not retard the dissolution of gold. In fact, it has been claimed that potassium ferrocyanide in the presence of oxygen is a weak solvent for gold (Hedley & Tabachnick, 1958). The main problem with the formation of this compound is the consumption of cyanide. Ferrocyanide contains six molecules of cyanide for each atom of iron {Fe(CN)64-} so the wasteful consumption of cyanide is greatly increased by its presence. Thiocyanate is also often produced during the reaction of certain iron sulphide minerals with cyanide, and contributes to the wasteful consumption of cyanide. In addition, environmental regulations in certain countries demand that thiocyanate be removed from the tailings, and this adds significantly to the cost of tailings treatment."

Jan 1, 2016

By E. Ghali, A. D. Bas

"Treatment of oxide, e.g. roasted gold ores has received relatively less attention than sulphidic ones and recently, handling of oxide gold ores is becoming essential. In this study, the influence of roasted gold ore (RGO) slurry (at 35% solid ratio) on the electrochemical dissolution of gold has been examined using pure gold and iron oxide minerals (hematite, maghemite, and magnetite) as disc electrodes by zeroresistance ammeter mode either in one or two separate containers. The presence of slurry decreased galvanic currents, i.e. corrosion rates due to the release and increase in the amount of soluble and/or insoluble species that could retard further the anodic behaviour of gold. Higher galvanic currents were observed in two separate containers than that in one container indicating the primary importance of galvanic interactions. SEM-EDS results observed iron hydro/oxide coatings on gold surface in case of magnetite test. However, in case of RGO electrode it is not a perfect passivation, although somewhat decreasing trend was observed on gold dissolution. These findings have revealed that passivation is not only a laboratory phenomenon, but also it could be responsible for the slowdown of gold dissolution in industrial practice.INTRODUCTIONThe cyanidation of gold is an electrochemical corrosion process thus; the dissolution of gold can readily be studied by electrochemical techniques. The outcome/summary of previous electrochemical studies of gold leaching can partially be summarized as follows: Filmer (1982) and Lorenzen and van Deventer (1992) reported the negative effect of pyrite and pyrrhotite on gold leaching due to the galvanic interactions; Aghamirian and Yen (2005) studied gold galvanic corrosion in presence of sulphide mineral electrodes only in one cell using zero-resistance ammeter (ZRA) mode; Dai and Jeffrey (2006) discussed, individually, the anodic and cathodic behaviours between gold and sulphide minerals, and Azizi et al. (2010, 2011) used a bed reactor to examine the influence of sulphide minerals on gold dissolution in one and two separate cells. Accordingly, a slowdown in gold leaching has generally been attributed to the passivation phenomenon, although the indication of this phenomenon is still an undergoing debate. For instance, Mrkusic and Paynter (1970) identified the passivation as the film formation of dissolved species from calcine, Crundwell (2014) explained passivation, in the case of corrosion of metals, as the formation of a layer which is composed of a new chemical species on the mineral surface and this layer inhibits or blocks further reactions. He suggested that passivation is related to the oxidation of the metal, and the formation of a passive layer that retards the rate of dissolution by several orders of magnitude. Consequently, galvanic interactions, passivation phenomena, or combinations of them are considered significant electrochemical factors affecting gold dissolution (van Deventer, Reuter, Lorenzen, & Hoff, 1990; Azizi, Petre, & Larachi, 2012). It is important to note that generalizing the influence of a mineral/metal on gold dissolution may not be correct in all cases, since contrary behaviours/results (for pyrite) have been observed (Aghamirian & Yen, 2005). Therefore, electrochemical study of gold is still a subject of research and need to be examined further in detail."

Jan 1, 2016

By D. A. Garland, A. D. Jackson

"Alanx ceramic/metal composites are proprietary products developed by Lanxide Corporation who joined with Alcan to form Alanx Products L.P. in 1988. Alanx ceramic/metal composites are composed of silicon carbide in a combined alumina and metallic aluminum matrix. In laboratory slurry wear tests conducted by Alanx ceramic/metal composites have shown to perform well against other wear resistant materials. At the Kidd Creek Concentrator Alanx CG896 ceramic/metal composite was tested in two pumping applications, the primary cyclone feed pumps and the filter feed pumps. In both instances the wear rates of the parts made of Alanx CG896 were far less than the gum rubber parts traditionally used. As of year to date September 1992 the unit cost to repair primary cyclone pump parts has dropped 58% from 1991 figures. For the filter feed pumps the unit cost to maintain the pumps has dropped by 33% as compared to 1990 figures. The total savings represented by implementation of Alanx wear parts, based on projected year end unit costs for 1992, as compared to 1991 costs for primary cyclone feed pumps and 1990 figures for filter feed pumps, is $166,753. INTRODUCTIONAt the Kidd Creek Concentrator the cost to maintain the primary cyclone feed pumps and the filter feed pumps was a constant concern. Rubber wear part consumption was quite high and the manpower required was considerable. For 1991 the total cost to maintain five primary cyclone pumps was $244,062. The cost to maintain the filter feed pumps in 1990 was $72,076. A wear material was needed that would increase the time between repairs and that would increase the reliability of these pumps between scheduled shut downs."

Jan 1, 1993

By J. P. Rajot, H. Mouzannar, M. Bost

"The design of rock foundations may need to evaluate shear strength of rock-concrete interface by performing laboratory direct shear tests. A series of tests were carried out on specimens for different values of the spacing free of encapsulating material about the shear plane and different values of normal stress. Different kinds of failure were observed and not necessarily at the rock-concrete interface. The spacing free of encapsulating material appeared to be of significant influence on the test results. A mechanical analysis is presented which illustrate the influence of the loading conditions in the direct shear box on the failure mechanism. INTRODUCTIONThe design of rock foundations subjected to significant lateral loads requires defining the value of the shear strength of the interface between rock and cast in place concrete. Verifying the stability against sliding of strip footings subjected to inclined loads (SETRA, 2009) or concrete gravity dams (CFBR, 2013) are common examples where design modelling approaches imply the shear strength, sometimes the deformation behavior, of the rock-concrete interface, more or less assumed as a failure plane.Defining the behavior of rock-concrete interfaces relates to tribology. Many studies have been conducted to improve the representation of this behavior (e.g., Johnston & Lam, 1989; Kodikara & Johnston, 1994; Gu, Seidel & Haberfield, 2003; Saiang, Malmgren & Nordlund , 2005; Fishman, 2008; Eltervaag, 2013; Gutierrez, 2013), raising many questions. The behavior appeared to be influenced by many factors such as the geometry of the interface which is not planar, the roughness of the natural rock, the rock mineralogy and the concrete formulation. In addition, the study of the shear strength of rock-concrete interfaces involves considering the two different deformation behaviors of both rock and concrete. Finally, the observed failure mechanism is strongly influenced by the initial cohesion due to adhesion between the two materials when concrete is directly cast onto rock."

Jan 1, 2015

By Wei Zhang, Jinhong Zhang

"The adsorption of ethyl xanthate on copper sulfides, i.e., chalcopyrite, chalcocite and bornite, has been studied in situ in aqueous solutions by applying an atomic force microscopy (AFM). AFM images show that xanthate, such as potassium ethyl xanthate (KEX), adsorbs strongly on chalcocite and bornite mainly in the form of insoluble metal xanthate, which binds strongly with the mineral surface without being removed by flushing with ethanol alcohol. This adsorption mechanism is totally different from the one obtained with chalcopyrite/xanthate system, during which oily dixanthogen is the main adsorption product on chalcopyrite surface. The findings obtained from the present AFM study suggest that an AFM image analysis is a powerful tool for the study of the collector’s adsorption on mineral surface and as well the development of novel collector for copper sulfide flotation.INTRODUCTIONIn mining industry, copper sulfide minerals, i.e., chalcopyrite, chalcocite and bornite, are usually separated selectively from non-valuable gangue by froth flotation, which treats the highest throughput and produces the maximum economic outcome of any surface chemistry process. In flotation, collectors are added into the pulp (mixture of water and fine-grained minerals) to selectively adsorb onto the target mineral and render its surface with high hydrophobicity, which is generally beneficial for a strong mineralbubble attachment and thus a high flotation recovery.The adsorption of collector on mineral surface, therefore, is vital for a successful flotation process and it has been studied by applying various surface analysis techniques, such as IR (Infrared Spectroscopy), CV (Cyclic Voltammetry) and XPS (X-ray Photoelectron Spectroscopy). (Poling, 1963; Allison et al., 1972; Mielczarski et al., 1984; Leppinen et al., 1989; Kartio et al., 1996) These studies have revealed a lot of information, such as the reaction, product and mechanism, of the adsorption of chemicals on mineral surface. It is also of great interest to directly get the image of adsorbed collectors on mineral surface changing with pulp chemistry, such as pH, redox potential, ionic strength and chemical’s dosage."

Jan 1, 2016

By W. P. Nash, T. E. Mccandless

"Abstract - Detrital minerals of upper mantle origin occur in Holocene conglomerates, pediments and antmounds, and in Oligocene conglomerates in the Green River Basin of southwestern Wyoming. The minerals are derived from disaggregated eclogite and peridotite, and are similar to minerals found in mantle- derived igneous rocks such as kimberlite and lamproite, the primary host rocks for diamond. The Green River Basin bisects the lamproite fields of the Leucite Hills (Wyoming) and Kamas (Utah) and overlies the Archean Wyoming craton, which makes the region favorable for diamond occurrence. Lamproite is the favored host for the indicator minerals because unusual high-Fe salitic diopside macrocrysts from the antmounds and from the ~1 Ma old Leucite Hills lamproites to the northeast are compositionally identical. The salitic diopside is uncommon in other igneous rocks and could be a new indicator mineral for use in lamproite exploration. The Green River Basin indicator minerals are eroded from the ~29 Ma old Bishop Conglomerate, whose source area is the Uinta Mountains to the south. No continuous mineral train exists between the Uinta occurrences and those in the Green River Basin. Assessment of the minerals using established and new geochemical criteria indicate that they formed in an oxidizing upper mantle and were transported to the surface by either kimberlite or lamproite. The existence of cogenetic diamond is unlikely based on the mineral chemistry, but selective removal of diamond indicator minerals through weathering and fluvial transport cannot be excluded. Diamonds and mantle garnets are present in the northeastern Uinta Mountains, but they originated as part of the Diamond Hoax of 1872. A representative mineral assemblage from the true igneous host of the indicator minerals is required to fully establish their economic potential. Post-Oligocene erosion and Pleistocene glaciation have hindered efforts to locate a bona fide igneous source for the indicator minerals. Résumé - Des minéraux détritiques provenant du manteau supérieur ont été trouvés dans des conglomérats, des pédiments et des monticules de fourmis de l’Holocéne, et dans des conglomérats de l’Oligocène du Green River Basin, au sud-ouest du Wyoming. Ces minéraux sont issus du démantellement d’éclogites et de péridotites, et sont semblables aux minéraux trouvés dans des roches ignées provenant du manteau, comme les kimberlites et les lamproïtes. Ces dernières sont les roches hôtes du diamant. Le Green River Basin recoupe les champs à lamproïte de Leucite Hills, au Wyoming et de Kamas en Utah, et il surmonte le craton archéen du Wyoming, connu pour la présence de ses diamants. La lamproïte est l’encaissant privilégié pour les minéraux «indicateurs» parce que des macrocristaux exceptionnels de diopsides salitiques riches en Fer, provenant des monticules de fourmis et des lamproïtes de Leucite Hill (~1 Ma), au nord-est, ont des compositions identiques. Le diopside salitique est rare dans les autres roches ignées et peut être un nouvel indicateur dans la recherche de lamproïte. Les minéraux «indicateurs» du Green River Basin proviennent de l’érosion du Conglomérat de Bishop, daté de ~29 Ma, dont la zone source est représentée par les Uinta Mountains, au sud. Aucune continuité des gisements minéraux n’existe entre les affleurements de Uinta et ceux du Green River Basin. La détermination des minéraux, utilisant des critères géochimiques anciens et récents, indique qu’ils se sont formés dans un manteau supérieur oxydant et qu’ils ont été remontés à la surface soit dans des kimberlites, soit dans des lamproïtes. La genèse du diamant n’est que peu liée à la chimie minérale, mais le lessivage d’indicateurs minéraux du diamant par altération météorique et par transport fluviatile ne peut être exclu. Des diamants et des grenats mantelliques sont présents dans le nord-est des Uinta Mountains, mais sont associés avec le Diamant Hoax de 1872. Un assemblage minéral représentati"

Jan 1, 1996