Search Documents

By Juergen Antrekowitsch, Stefan Steinlechner

"Waelz oxide from steel mill dust recycling is usually sold to the primary zinc industry, where it is first charged to the roasters to eliminate the remaining fluorides and chlorides. This limits the overall amount of secondary materials which can be used because of different operating problems in the roasters. Another option, in the case where the halides are low, would be direct leaching with low or medium concentrated sulphuric acid. Unfortunately, because of the carryover of some steel mill dust, iron is also present in the Waelz oxide, reaching contents up to 5 wt.%. Since the objective is to treat the solution more or less directly by electrowinning, with only a few simple preliminary purification steps, iron in the solution is a very important factor. Various trials have been done to investigate the dissolution behavior of the iron contained in the Waelz oxide. Although the zinc extraction should reach a maximum, all other elements, especially iron, should be low. This paper describes the results of our research in this area and offers possible options for Waelz oxide utilization. There is also a focus on how other elements, present in the material, influence the dissolution behaviour of zinc and iron, and whether a loss of zinc is unavoidable, if low iron dissolution is required.INTRODUCTION One of the most important secondary zinc resources is the zinc oxide originating from steel mill dust recycling. For the treatment of high zinc containing steel mill dusts, the Waelz kiln process is the so called “best available technology” and it dominates the industry, with roughly a 90% market share. The product Waelz oxide contains mostly zinc oxide, but it also contains lead compounds and halides due to evaporation with the zinc. In addition, it contains iron and some slag compounds due to mechanical carry-over. The presence of halides limits the use of the material as an alternative concentrate for primary zinc electrowinning. Such halides can be reduced to a certain extent by washing and/or solvent extraction (see following chapter). Although lead is not troublesome and theoretically represents a second recoverable valuable metal, iron is unwanted and causes additional problems during leaching. Even though Waelz oxide is generally a highly welcome input material in primary zinc metallurgy, due to its high zinc content, it still contains halides, and in the majority of cases, the oxide must first be treated in a roasting process. Different circumstances, like accretion formation because of the lead and halogen compounds as well as unwanted cooling effects in the roaster, limit the amount of Waelz oxide which can be substituted for the primary concentrate. Another, even more limiting factor, is the allowable concentrations of chlorides and fluorides in zinc electrowinning, the last step in the primary zinc processing route (Ruetten, 2011)."

Jan 1, 2016

By J. Nsasi Bakambu

This paper describes an autonomous platform for exploration and navigation within networks of tunnels, as those typically found in underground mines and caves. In the exploration mode, a remotely located supervisor instructs the platform to move through successive sections of the network, gathering range data that is, then, concatenated into 2D/3D survey maps of the environment. In the navigation mode, the supervisor specifies high-level missions on the previously acquired survey maps. A motion planner, then, translates each mission into a set of consecutive navigation actions, separated by natural landmarks. Mission execution consists of detecting landmarks, self-localizing and performing the planned navigation actions.

May 1, 2003

By Eric Poulin, Anthony Clapperton, Jocelyn Bouchard, Jaime Cristobal Rojas-Montes, Benjamin Legare

"Several grinding mill dynamic simulators have been developed in the last half-century. However, complete circuit simulations are mainly limited to academic investigations, and on-site applications for advanced control or real-time optimization are scarce. One particular issue that has certainly curbed a more widespread use is the time and efforts required for model calibration. This paper illustrates this challenge and presents a calibration method based on dynamic simulation using industrial data and laboratory testwork. The simulator models discussed originate from the work of Austin and Luckie (1972) for grinding mills, and Plitt (1976) for hydrocyclones. A two-stage approach based on a least squares minimization allows determining calibration parameters values. Firstly, laboratory testwork are required for characterizing breakage coefficients of the ore. Secondly, step change responses and their simulation— effect of ore and water feed rates on output flow rates and size distributions—allows identifying transport/mixing conditions. Simulation results are in agreement with actual process responses to variations of feed conditions obtained from a plant survey.INTRODUCTIONDynamic models for grinding circuits has been intensively studied since the 1970's notably by Austin and Luckie (1972b), Klimpel and Austin (1984), Rogovin and Hogg (1988), Napier-Munn et al. (1996), Liu and Spencer (2004), and King (2012) among others. The resulting models primarily serve in simulation applications for process equipment sizing, which incidentally also helps developing a better understanding of comminution operations. An obstacle curbing a more widespread and targeted use of grinding simulation for process control and optimization purposes is the time and efforts required for dynamic model calibration. It remains a cumbersome task that is typically not well detailed in technical papers. This could explain why dynamic process simulators are mainly confined to academic applications."

Jan 1, 2016

By G. E. Wood

THE INSTABILITY of copper prices and their low levels since late 1974 are of great concern to both producers and, to a lesser degree, consumers of copper. The price levels portrayed by the "neutral long-term" price trend are assumed to have been enough to encourage sufficient investment to provide adequate world production capacity and yet not so high as to encourage development of excessive over capacity. The identification of the present level of this trend has taken on special importance for governments and for corporations active in the world copper industry. One approach to the possible determination of such a price is through the use of moving averages. In this way, the effects of relatively short-term price movements can be dampened, as can those related to business cycles. From such averaged price data, long-term trends can be sought over a selected time period. The choice of the past time period for which a price trend is sought may have a major effect on the result'. For example, in the period 1885-1973, the long-term price trend for copper in constant dollars showed a decline, whereas in the period 1919-1973 it was rising. For the purposes of discussion, an appropriate choice of period might be a relatively short and recent one so that the majority of the present cost factors would be present throughout. It should also be long enough to cover a number of full business cycles.

Jan 1, 1977

By S. Kaushik

The control room in a mineral processing plant has become increasingly complicated with complex unit operations coupled with rapidly evolving systems of sensors and control. Even with significant automation, human intervention is required to counter various scenarios that play out every day. A typical control room operator must monitor over 300 individual points of data in order to ensure the safe and efficient operation of the plant. At the same time, the experience of the workforce is decreasing as operators retire and the new generation enters the concentrators. Global competition for skilled operators continues to be strong and the opportunity to apprentice has diminished. The challenge is to provide a skill foundation for the operators so that they can be effective in the concentrator in a timely and safe manner. Progressively, the industry is turning to dynamic simulation tied into the control system. The simulator environment operates behind the control system to emulate the plant operation, reacting as the plant would when a change is made. The operator drives the process, with realistic feedback, which enables learning in a safe environment. This paper will take the reader through a green-field case study and discuss the effectiveness of integrating an operator training simulator (OTS) on the operator’s learning curve.

Jan 1, 2014

By J. P. Sairrlon, K. G. Wheeland, K. J. Mintz, B. J. Kiener

Iwenty-one ore dusts of varying mineralogy, sulphur content and reputed in-mine explosibility were selected from eight mines. After chemical and mineralogical analysis and sieving into two size fractions (+45/ -63 microns and -45 microns), these sarrples and seven pure minerals were tested for explosibility in oxygen in a Harbnann chamber. '!he maximum explosion pressures and maximum rates of pressure do not correlate with sulphur content alone; the types of minerals are also .important. Residues were analyzed to check the combustion reactions. Further comparisons between laboratory and mine results are planned to improve predictability.

May 11, 1988

By Walter Curlook

"With Inco recording record profits over the past year, most people have forgotten the painful years of the last recession/depression when Inco was losing up to a million dollars a day for a short period . While high nickel prices have contributed to the exceptional recent profits, the real achievements stem from the tremendous advances in productivity and cost improvements that make Inco one of the lowest cost nickel producers.Some of the major advances in productivity have occurred in the mines. The establishment of Mining Research Departments in both Thompson and Copper Cliff in 1979/80 provided the stimulus and the opportunity to dedicate personnel to specific research projects, on a full-time basis; and more particularly to concentrate on the efficiency of the total mine system. The Copper Cliff North Mine was brought back into production as a research mine dedicated to the development and testing of new mining methods and equipment. A shop facility known as the ""Murray Shop"" was set up as the centre of innovation for the development and construction of prototype equipment required for new bulk mining methods. While other expenditures were being curtailed , investment in mining research was being increased. An early success was an ""in the hole"" drill that could be broken down into small components to access even the remotest sectors of a mine to convert labour intensive undercut-and-fill mining to "" vertical crater retreat "" , VCR, bulk mining. A new mine manufacturing company-Continuous Mining Systems-was incorporated with the objective of building innovative mining equipment, with strong focus on automated continuous sytems. Continuous Mining Systems has now grown to a $25 million per year business. With these synergistic thrusts, the VCR bulk mining method was implemented in all of the Ontario Division mines, raising the percentage of ore mined by bulk mining techniques from 320/0 in 1981 to over 90% today. Coupled with re-designed job responsibilities, sup- ported by appropriate training, mine productivity more than doubled. It was discovered that VCR mining could be adapted to the narrower Thompson mine ores with identical improvements in productivity. Development of the Thompson Open Pit North had an additional favourable impact on production cost s in Thompson. The timing of the open pit development could not have been better. It permitted Inco to rapidly increase production at high productivity and low cost, in years of record demand and prices."

Jan 1, 1990

By Y. Kocaefe, D. Bhattacharyay, D. Kocaefe

The carbon anodes used in the electrolytic production of aluminum are made of petroleum coke, recycled anodes and butts, and coal tar pitch. Due to technological advances in the aluminum production technology, aimed at increasing production and decreasing energy consumption and greenhouse gas emissions, better quality anodes are required. Presently, the anode quality is evaluated by visual inspection and the analysis of a small core taken from 1.5-2% of the anodes produced. The visual inspection is susceptible to human error and limited to surface imperfections. The analysis of cores takes time, and therefore, it is difficult to determine the existence of a problem and intervene at the right time. In addition, the core does not represent the whole anode due to the non-homogeneity of anodes. A validated online anode quality control system can highly improve the situation. In this article, an electrical resistivity measurement method developed for this purpose is presented.

Jan 1, 2014

By A. R. Barnes, R. Pandher, T. Shannon, P. Gover

Following the closure of the Glencore Zinc Brunswick mine, the Glencore Brunswick Smelter has transitioned to treating external feeds, and currently treats a number of secondary Pb-Zn concentrates. Processing these concentrates has in some cases been challenging due to the diverse mineralogy of the feeds. Certain feeds are difficult to ignite or show inadequate sulphur removal during oxidation on the sinter strand, while in other cases, combinations of feeds produce a sinter with unsuitable properties for further handling. This paper discusses two methods developed in collaboration with XPS Consulting & Testwork Services to characterize these feeds prior to processing them and to identify which ones are most likely to pose challenges during processing.

Jan 1, 2014

By Luis Bergh, Juan Olivares, Juan Durán, Juan Yianatos

"In the last decades heuristic approaches based on logic rules have been one favored tool to control flotation units and plants on top of distributed control systems. Fundamental knowledge on flotation processes, expressed in reliable models, and programs to assure the quality of the information, contained in available measurements, are still insufficient to develop robust predictive control strategies. In this paper the idea of using simplified models, when a known disturbance is coming into the process, is explored. As a first approach, the set points of the froth depth and air flow rate controllers are estimated based on this model. Since these target predictions are only approximate, a conventional feedback expert system, based on logic rules, continues the task of calculating the set points of the distributed controllers, in order to decrease the gap between actual and desirable metallurgical targets. This combined actions permitted a fast response of the process to change the operation of the circuit when a measured disturbance is detected. This control system was implemented and experimentally evaluated in a pilot rougher flotation circuit, with three pneumatic cells, with froth depth and air flow rate controllers in each cell. Since the circuit is operated for the air-water system, a phenomenological model, with parameters estimated from industrial data, is fed on-line with real operating variables and virtual values, characterizing the feed (grades, solids%, particle size distribution), in order to predict the metallurgical targets (recovery and concentrate grade). Several cases are discussed showing the benefits of this control system and the possible improvements to work on. INTRODUCTIONToday, large size mechanical flotation cells of 100 to 300 m3 are used in rougher operation in different flotation industrial plants, in Chile and worldwide. However, in spite of the advances in fundamental research and the notable growing in equipment size, with more complete instrumentation systems, there are still a lack of reliable data for industrial flotation modeling and simulation to advance in better control systems design."

Jan 1, 2016

By M. Tanaka, H. Narita, T. Fuchikami, K. Morisaku, K. Nagao, T. Yoshida, K. Kuroda

The effect of various N-substituents on the performance of amide-containing tertiary amine compounds in the extraction of Rh(III) from HCl solutions was investigated to optimize the structure of these compounds for industrial use. It was found that N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide)amine and tris(N-di-2-ethylhexyl-ethylamide)amine, which have long, branched alkyl chains, were suitable for Rh extraction, because they were soluble in a practical diluent (80 vol% n-dodecane?20 vol% 2-ethylhexanol) and stable against highly concentrated HCl/Rh solutions, and showed high selectivity for Rh(III) over Pd(II) and Pt(IV).

Jan 1, 2014

By G. Dodbiba, A. Otsuki, T. Fujita, J. Ponou, A. Shibayama

"The different types of nano to submicron particles, which are well-dispersed nano particles, coagulated nano particles or settled submicron particles, have been measured by the interactive force apparatus (IFA). The information is very useful for mineral processing treatment. The IFA can measure the particle size distribution in low to high concentration of particles in liquids and non-light transparent liquids. Here, mainly the emulsion and bubble size measurements are described.Emulsion (w/o type) is prepared with oil and water mixture. The nano to micro emulsion particle size is usually measured by light scattering method. The particle size distribution of emulsion of light oil measured by IFA agreed well with the one by the dynamic light scattering (DLS) method. The water size distribution in emulsions of gasoline is difficult for the small reflection index and C heavy oil is difficult for the black color by DLS method. The IFA can measure both emulsions.There are many methods to measure fine air bubbles, however, the finer nano size measurement apparatuses are DLS method and IFA. A “ghost” peak appeared in the large particle micron meter size in DLS method. The mean diameter in IFA is similar with DLS for the nano meter size. INTRODUCTIONParticle size distribution measurement of nano to submicron particle, emulsion and bubble size distribution are very useful for ultrafine particle separation and characterization of fine particles by the necessity of recent fine minerals separation (For example, Li et al.2016, Mikhlin et al.2016, Wang et al.2013). As for the size measurement of solid particles in liquids, three different types of nano to submicron particles, that are well-dispersed nano particles, coagulated nano particles or settled submicron particles, have been measured by the interactive force apparatus (IFA). The particle size distributions are compared with the one of dried particles measured by TEM or SEM. The well-dispersed nano particle size distribution by IFA is influenced by the nano size surfactant micelles and becomes smaller, when compared with the TEM result. The size distribution of nano size of magnetite particles in water is influenced by the isoelectric point and the mean diameter of coagulation becomes larger. The particle coagulation in diluted suspension is about 2nm smaller when compared with the higher concentration. The submicron nickel particle size distribution is well agreed the result by SEM. The coagulation effect is small in the submicron size of nickel powder in water (Fujita et al., 2013). In this paper, the emulsion and bubble size measurements are mainly described."

Jan 1, 2016

By P. Woo, N. Brodusch, R. Gauvin, H. Demers

For developing new technologies, it is important to characterize the microstructure of materials with high spatial resolution at the nanoscale. To achieve high resolution, field emission scanning electron microscopes (FE-SEM) were developed. These microscopes allow working at low accelerating voltage, below 5 kV, to take advantage of the reduction of the interaction volume with accelerating voltage. Furthermore, their higher gun brightness compared to conventional thermo-electronic emitters, allow a probe size at the nanoscale. At low accelerating voltage, the emission volume of backscatter and secondary electron (SE) of the type II signals approach that of SEI signals. However, it is not enough to reach the highest resolution. A magnetic field above the sample improves the spatial resolution by collecting mostly high-resolution signals. In addition, the energy-filtration of the electron signals allows selecting the type of contrast detected: topographic, compositional, or crystallographic. The development of these new technologies permits to extend the imaging capabilities of the SEM towards new nanoscale applications.

Jan 1, 2014

By M. H. Rana

"A survey of our knowledge in the field of rock mechanics is presented from the viewpoint of applications in the mining industry. Aspects of rock mechanics of special interest to the industry are enlarged upon, with emphasis on the avoidance of over-generalization. The relationship between fundamental and practical rock mechanics is discussed, and the need for cooperation between the university and industry to further our knowledge of -useful rock mechanics is emphasized. An attempt has been made to establish the scope of rock mechanics, as applied to problems in the mining industry. This is brought about by projecting rock mechanics as a tool to be intelligently used rather than magic, capable of producing ""miracles."" Continued education is important for individuals engaged in the application 0f rock mechanics in the mining industry. The scope of this education is discussed from a viewpoint of better communication between industry and the education and/or re-search establishments engaged in this work.Finally, the dangers of over-emphasis on rock mechanics are mentioned, but a justification of the in-vestment in rock mechanics programs in mines is also presented."

Jan 1, 1966

By D. B. Dreisinger, M. R. Tavakoli

Vanadium has been produced from a variety of sources. This metal is known to make aqueous solutions of complex speciation as a function of vanadium concentration and pH. Considering the method of leaching, the impurities in the PLS and the planned vanadium product, different extractants and flowsheets can be applied for solution purification. In this paper, purification of vanadium leaching solution using organophosphorus, solvating and amine extractants will be reviewed. This review will be focused on vanadium separation from iron, molybdenum and uranium which are often present in vanadium resources including primary ores, fly ashes and spent catalysts.

Jan 1, 2014

By Michel Grenier, Robert Scott, Mahendra Gangal, Andrew Dasys

This research project which took place at Brunswick Mining and Smelting's Brunswick mine, was undertaken to assess the ability of new diesel engine technology to meet current and anticipated underground worker exposure limits to diesel exhaust contaminants. Concentrations of CO, CO2 NO, NO2 SO2 and respirable combustible dust (RCD) were measured in a remote mine area where a haulage truck was operating under simulated duty cycles. The 26 ton haulage truck was equipped with a 300 hp, electronically controlled engine. Fresh air was supplied to the area as per the MSHA certification document for this particular engine. Results showed that while the vehicle operated in a normal and realistic duty cycle, the concentrations of contaminants remained well below the ACGIH guidelines for the threshold limit values (TLV)for exposure. While operating at 630/0 of maximum horsepower (26 tons of ore in the dump), the time-weighted average exhaust gases concentrations (CO, CO2 NO, NO2 and SO2) never exceeded 150/0 of their respective TL Vs. ReD concentrations in this instance were measured at 0.59 mg/mJ or 39.30/0 of the exposure limit suggested by the Canadian ad hoc Diesel Committee. The Air Quality Index was 1.55 or 520/0 of the maximum suggested value for exposure.

Jan 1, 1994

By Lev Filippov, Saeed Farrokhpay

"Flotation process has had less success to recover nickel from laterite ores. Nickel in laterite ores is often finely disseminated in various minerals in very fine size. Therefore, fine grinding should be used to liberate nickel containing particles. Particles resulted from fine grinding are often very fine, and recovery of such particles is generally low using conventional flotation methods. One option to overcome this problem is enhancing the particle-bubble interaction by increasing the particle size and forming flocs. Selective flocculation of fine particle can be therefore the key to enhance the flotation performance of low grade laterite ores.INTRODUCTIONThe majority of the world’s nickel resources occur as laterite ores which are complex, low grade and expensive to treat using conventional smelting and high temperature and/or high pressure autoclave methods (Xu et al., 2013). While about 70% of the nickel resources are contained in laterites, only 40% of the world’s nickel production comes from these ores. Researchers have tried to improve the nickel laterite flotation recovery by using a number of feed preparation techniques. For example, in a study on a laterite ore sample from Australia, flotation tests on a narrow sized fraction of 38-75 µm resulted in only a small increase in the nickel content, from 1.0% to 1.4% (Quast et al., 2015a). In fact, no physical separation technique (including flotation) has been able to dramatically upgrade nickel in laterite ores (Quast et al., 2015b). Thus the challenge of processing low grade nickel laterite ores still exists. This paper aims to explore the possibility of applying selective aggregation in pre-concentrating of valuable minerals in nickel laterite ores."

Jan 1, 2016

By Ken G. Stowe, Stephen L. Chryssoulis, Joe Y. Kim

"Lead ions originating from galena during processing of complex sulphide ores migrate to ""cover"" the surface of sphalerite and iron sulphide mineral rarticles, and cause poor selectivity in differential flotation. Generally in sulphide ore processing, the lead activated minerals float in the Cu/Pb circuit. Subsequently, surface lead complicates the zinc flotation circuit by lowering the concentrate grade due to the co-flotation of lead- activated iron sulphide minerals. The effect of lead in the differential flotation of sphalerite from Cu-Pb-Zn and Pb-Zn ores is discussed. Plant and laboratory test data are interpreted by determining the surface composition of individual grains of sphalerite and iron sulphide rarticles using two surface analytical techniques, Laser Ionization Mass Spectrometer (LIMS) and Time of Flight-Secondary Ion Mass Spectrometer (TOF-SIMS). Cationic and anionic species on the surface were analyzed to elucidate the phenomena.IntroductionSurface properties play a critical role in many aspects of mineral processing such as flotation, flocculation, etc. An understanding of interaction mechanisms of different reagents (inorganic cations and anions, collectors, regulators, etc.) with mineral surface in an aqueous solution is a very important pre-requisite in achieving the desired selective flotation. In the flotation of complex sulphide ores, the flotation collectors respond to the activation of minerals such as sphalerite, pyrite etc. by heavy metal ions of Cu, Pb or Ag, which is a strictly surface phenomenon."

Jan 1, 1995

By Wengui Su, Qi Zhang, Junce Wang, Zhijun Ma, Xingyuan Weng

"Mesoporous materials with large specific surface area, pore size, and pore volume have been widely used in many fields such as ion exchange, gas separation, adsorption, and catalysis. Mesoporous materials prepared using natural zeolite have the advantages of both acid and alkali resistance. In this work, mesoporous materials were prepared using natural zeolite as the starting material and diethylenetriamine (DETA) as a template. The resulting samples were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and N2 adsorption-desorption experiments. The influence of the crystallization temperature and crystallization time on the specific surface area, pore volume, pore size, and morphology of the resulting mesoporous materials are also discussed. Our results show that for an increase in both the crystallization temperature and time, the average pore size first increases then decreases, while the specific surface area first decreases then increases. Based on this work, we concluded that the optimal crystallization temperature was 2003 and the optimal crystallization time was 60 h. These conditions gave an average pore size of 17.93 nm, a pore volume of 0.048 cm3g-1, and a specific surface area of 16.48 m2g-1.INTRODUCTIONMesoporous zeolite, as the name implies, is a highly porous crystalline zeolite. This material is of interest due to its high hydrothermal stability, its adsorption and diffusion properties for macromolecules, and its excellent selectivity and activity as a catalyst. In recent years, it has become a hot spot among research of porous catalytic materials and has been widely used in petroleum and natural gas processing, fine chemical processing, various adsorption and separation tasks, and other uses (Carvalho & Urquieta- Gonzalez, 2015; Teh, Triwahyono, Jalil, Mukti, Aziz, & Shishido, 2015)."

Jan 1, 2016

This paper presents the results of research aimed at proposing new solutions in the area of belt conveyor elements. Many factors, such as energy consumption costs, and operating costs of belt conveyor elements, including belts, idlers and drives have an impact on the operational costs of conveyors. The paper presents special tests of new materials for the bottom cover of an energy-saving belt conveyor, which decrease rolling resistance. It also presents large-scale in-situ tests of a high-output belt conveyor for the purpose of simultaneous measurements of various types of conveyor belts (standard vs several energysaving types) under typical operating conditions of a lignite surface mine. Improvements in materials used for the bottom belt covers, supported by specially developed comprehensive tests of the new types of belts have provided valuable results of various proposed solutions. Since the tests of belts were done at exactly the same time and in the same operating conditions, direct comparison of the results is valid and should lead to a substantial decrease in the conveyors? drives? energy consumption, which will improve the effectiveness of belt transport and minimize its negative influence on the environment.

Aug 1, 2013