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By Z. Bibak, S. Banisi, A. Ghasemi, E. Nematollahi

"The major importance of liners in grinding is their role in providing an appropriate trajectory for the charge. Since it is not possible to study the charge movement by direct observation in operating industrial mills, this task is accomplished by physical (laboratory), and/or, mathematical (software) methods. Because of the high cost and a longer time required for a physical analysis, mathematical simulations have become more common. Simulation of the effect of liner shape on the charge movement has provided a means to select a proper design based on the operational objectives and conditions. Furthermore, the liner shape changes due to wear and impact during operation, which will influence the charge trajectory. This adds more of an incentive to use simulation. These changes in liner could be predicted through liner profile measurements during operation and/or simulation. In this research, an inhouse developed DEM software called KMPCDEM © was used to simulate the charge movement in industrial plant SAG mills. A geometrical method of implementing the shell liners on SAG mills at the Sarcheshmeh (9.75×4.87 m) and the Gole-E-Ghohar (9×2.05 m) operations facilitated the software simulation. Point by point implementation of the measurements of liner profiles of these mills enabled the study to trend the change in the charge movement as the liners wear. Comparison of the simulation to a laboratory mill (1 m diameter) showed that the difference between the measured and predicted charge impact point, shoulder angle and toe angle were 6, 4 and 3°, respectively.INTRODUCTIONComminution is the most energy intensive operation constituting the major portion of operating and capital costs of a mineral processing plant. In the last decade, a vast number of research was aimed at studying various aspects of grinding with the aim of performance improvements (Davis, 1919; Mishra & Rajamani, 1990; kalala, Breetzke, & Moys, 2008). Mill liners transfer the input power to the charge and play a significant role in affecting the motion of the charge (Mclvor, 1983; Mishra & Rajamani, 1990; Radziszewski, 1997; Van Nierop, Glover, Hinde, & Moys, 2001; kalala et al., 2008). Lifters are usually used with mill liners to extend their life and to enhance the grinding and impact breakage efficiency. Mill lifters are used to raise the grinding media and ore to transfer the energy from the mill to the load (Rezaeizadeh, Fooladi, Powell, & Weerasekara, 2010)."

Jan 1, 2016

By Z. Bibak, S. Banisi, A. Ghasemi, E. Nematollahi

"The major importance of liners in grinding is their role in providing an appropriate trajectory for the charge. Since it is not possible to study the charge movement by direct observation in operating industrial mills, this task is accomplished by physical (laboratory), and/or, mathematical (software) methods. Because of the high cost and a longer time required for a physical analysis, mathematical simulations have become more common. Simulation of the effect of liner shape on the charge movement has provided a means to select a proper design based on the operational objectives and conditions. Furthermore, the liner shape changes due to wear and impact during operation, which will influence the charge trajectory. This adds more of an incentive to use simulation. These changes in liner could be predicted through liner profile measurements during operation and/or simulation. In this research, an inhouse developed DEM software called KMPCDEM © was used to simulate the charge movement in industrial plant SAG mills. A geometrical method of implementing the shell liners on SAG mills at the Sarcheshmeh (9.75×4.87 m) and the Gole-E-Ghohar (9×2.05 m) operations facilitated the software simulation. Point by point implementation of the measurements of liner profiles of these mills enabled the study to trend the change in the charge movement as the liners wear. Comparison of the simulation to a laboratory mill (1 m diameter) showed that the difference between the measured and predicted charge impact point, shoulder angle and toe angle were 6, 4 and 3°, respectively. INTRODUCTIONComminution is the most energy intensive operation constituting the major portion of operating and capital costs of a mineral processing plant. In the last decade, a vast number of research was aimed at studying various aspects of grinding with the aim of performance improvements (Davis, 1919; Mishra & Rajamani, 1990; kalala, Breetzke, & Moys, 2008). Mill liners transfer the input power to the charge and play a significant role in affecting the motion of the charge (Mclvor, 1983; Mishra & Rajamani, 1990; Radziszewski, 1997; Van Nierop, Glover, Hinde, & Moys, 2001; kalala et al., 2008). Lifters are usually used with mill liners to extend their life and to enhance the grinding and impact breakage efficiency. Mill lifters are used to raise the grinding media and ore to transfer the energy from the mill to the load (Rezaeizadeh, Fooladi, Powell, & Weerasekara, 2010)."

Jan 1, 2016

By Mohammad Noaparast, Babak Fotoohi

"Due to certain advantages in (semi-)Autogenous-Ball mill circuits in most of the high-throughput ore grinding units of mineral processing plants, much attention is paid to optimize the mill performance. Despite the maturity of the grinding mill mechanical design, there had been made less attention to the efficiency of the grinding media in the past. In this research, the possibility of establishing a relationship between liner/lifter wear rate and variations in the composition of the iron ore (from Chadormalu mine) is investigated.Measurements and determination of liner/lifter wear rates and patterns concluded in recognition of critical liner segments exposed to much abrasion during the ore grinding. After metallurgical analysis of liner materials and correlation of wear rate with the ore composition, the homogeneity in the metallurgical microstructure of the alloyed steel (such as the uniform distribution and amounts of the constituent phases) was determined as the most influential factor in the response of the liner/lifter to the variations in the ore composition. Magnetite with greater abrasion index than hematite, in finer particles, is responsible for additional abrasion of liners; hematite with greater work index exists in the mill with larger particle sizes, thus it could produce wear on liner parts with less tolerance to impact as is the situation for martensitic steels.INTRODUCTIONThe mineralization in Chadormalu plutonic iron ore deposit is consisted of mostly magnetite, hematite, martite, apatite, quartz and carbonates. The average composition of the ore is presented in Table 1. In the processing circuit, the gyratory crushed ore reduced to 30 cm would finally be the feed to three similar 32’ semi-autogenous mills in parallel processing lines. The pulp in the mill would have the characteristics mentioned in Table 2. The quality of the mill output has its direct effect on the downstream processes either physically or chemically (e.g. in cycloning or flotation respectively). In order to take advantage of optimum performance for these circuits, a close control of the ore grinding conditions is necessary; because any shortages in throughput, liner/lifter damage or changes in ore composition could bring the unexpected casualties. In this work, it has been attempted to find (possibly) a reasonable relationship between variations in ore characteristics together with liner quality and the amount of wear rate in different liner/lifter segments of a semi-autigenous mill. Liner/lifter segments are supplied by three different domestic steel making companies. The alloy structure of the liners/lifters is made up of pearlitic chromoly steel."

Jan 1, 2005

By P. Roghanchi

The difficulties associated with performing direct tensile strength test lead to development of indirect test methods, which are simple, less expensive, and less time consuming. Splitting tensile strength test (Brazilian test) is performed by applying two opposite concentrated compression load across the diameter of a disk specimen until the failure occurs along the loaded diameter. Theoretically, the load is applied over a small width as a line load, however, by increasing the load, the contact width between the loading jaw and the specimen increases as the specimen deforms. The main aim of this study is to investigate the stress distribution in (1) regular Brazilian specimen in traditional tests with loading jaws and (2) flattened Brazilian specimen with flat platens. A series of the splitting tensile strength tests and uniaxial compression strength tests are performed on three rock types: rhyolite, basalt, and limestone. Further, Numerical modeling studies are performed to investigate the effect of the contact between jaw and Brazilian specimen on stress distribution in the disc specimen based on the results from the experimentation. Finally, the stress distribution in the traditional Brazilian test specimen and the flattened end Brazilian test specimen were compared.

Feb 23, 2014

By J. A. Organiscak

Two types of airflow splitting methods for improving longwall dust control were investigated by the National Institute for Occupational Safety and Health's Pittsburgh Research Laboratory. Investigated were a translucent mesh barrier and a staged spray barrier system to confine the shearer-generated dust to the coal-extraction side of the longwall face while maintaining a cleaner split of airflow on the opposing worker walkway side of the longwall face. In laboratory experiments and in a longwall field evaluation, the translucent mesh barrier was shown to provide notable dust-control effectiveness for a distance of up to 60 m downstream of the shearer, provided that the mesh barrier remained relatively parallel to the airflow. The staged spray barrier system showed marginal dust-control effectiveness in the laboratory and, therefore, was not field tested.

Jan 1, 2000

By J. A. Organiscak

Two types of airflow splitting methods for improving longwall dust control were investigated by NIOSH's Pittsburgh Research Laboratory. These methods included a translucent mesh barrier and a staged spray barrier system to confine the shearer-generated dust to the coal extraction side of the longwall face while maintaining a cleaner split of airflow on the opposing worker walkway side of the longwall face. The translucent mesh barrier was shown to provide notable dust control effectiveness up to 60 m downstream of the shearer in both the laboratory experiments and a longwall field evaluation, provided the mesh barrier remains relatively parallel to the airflow. The staged spray barrier system showed marginal dust control effectiveness in the laboratory and subsequently was not field tested.

By J. A. Organiscak

Two types of airflow splitting methods for improving longwall dust control were investigated by NIOSH's Pittsburgh Research Laboratory. These methods included a translucent mesh barrier and a staged spray barrier system to confine the shearer-generated dust to the coal extraction side of the long wall face while maintaining a cleaner split of airflow on the opposing worker walkway side of the longwall face. The translucent mesh barrier was shown to provide notable dust control effectiveness up to 60 m downstream of the shearer in both the laboratory experiments and a long wall field evaluation, provided the mesh barrier remains relatively parallel to the airflow. The staged spray barrier system showed marginal dust control effectiveness in the laboratory and subsequently was not field tested.

Jan 1, 1999

By Brendan Demich, MAHIYAR F. NASARWANJI, Alan G. Mayton

During dusk, nighttime and dawn operations, effective illumination is a crucial component of safety for getting on/off mobile surface mining equipment and for preshift inspections. U.S. National Institute for Occupational Safety and Health (NIOSH) researchers examined whether illuminance levels could be improved for ingress/egress systems and preshift walkaround inspections of equipment using light-emitting diode (LED) area luminaires. Illumination and glare were key metrics evaluated. Although headlamps provided adequate illumination, LED area luminaires illuminated a much broader area compared to the narrow spot lighting of the headlamp. Hence, the use of additional area luminaires can increase slip-trip-fall (STF) hazard awareness and detection. Furthermore, a commercially available luminaire demonstrated better results than a custom LED luminaire relative to discomfort and disability glare.

By Brendan Demich, MAHIYAR F. NASARWANJI, Alan G. Mayton

Nonfatal injuries from slips, trips, and falls (STF) that occur at surface mines can result from inadequate lighting. Mobile equipment operators are among the occupations associated with the nonfatal incidents reported to the U.S. Mine Safety and Health Administration (MSHA). In addition, getting on/off the equipment (ingress/egress) frequently adds to the highest proportion of nonfatal incidents. Accordingly, researchers at the Pittsburgh Mining Research Division (PMRD), National Institute for Occupational Safety and Health (NIOSH) conducted a field study to investigate lighting on haul trucks and wheel loaderswith regard to glare and illuminance levels recommended by the Illuminating Engineering Society (IES). The objective was to determine whether two light-emitting diode (LED) area luminaires—a Mr. Beams® (model MB390 Ultrabright) (area luminaire-1) and a NIOSH-developed Saturn (custom-designed for a mine roof bolter study) (area luminaire-2)—could complement a headlamp luminaire. Measured levels of visual tasks, with the headlamp alone and the area luminaires plus the headlamp, demonstrated that illuminance met or exceeded IES-recommended levels. Nevertheless, the area luminaires illuminated a much broader area, which is key to increasing hazard awareness. Discomfort and disability glare were lower with area luminaire-1 than with area luminaire-2. Differences in glare were more noticeable for newer models of haul trucks and loaders featuring updated ingress/egress system designs. This study demonstrates that commercially available luminaires, such as area luminaire-1, are capable of complementing headlamp lighting, and can thus improve a miner’s ability to detect and avoid STF hazards.

Jun 17, 2020

By O. C. Carter, B. J. Scheiner

The Bureau of Mines is investigating the effects of rainfall and gypsum/cooling pond water on the rate of metal and nonmetal ion mobility through phosphogypsum stacks located in central Florida. Since leachate contains metal and nonmetal ions that have the potential for migration into surface and groundwater, laboratory column leach tests were conducted. Synthetic rainwater was passed through the column and metal and nonmetal ion migration was monitored. Similar experiments were conducted using a number of synthetic solutions which simulated a number of different compositions of gypsum/cooling pond water. Results indicate that within the first five pore volumes most of the mobile metals and nonmetals were removed.

Jan 1, 1992

By E. M. Timoshenko, A. V. Tarasov

The results of laboratory, bench-scale and semi-commercial investigations of a method for adding surfactant (technical-grade lignosulphonate) to the process of pressure leaching of nickel-containing pyrrhotite concentrates have been discussed. Lt has been demonstrated that feeding of technical-grade lignosulphonate distributed along the length of an autoclave ensures a reduction in its requirement by a factor of 1.5 to 2 as compared with single-point feeding; it also results in a decrease by 5% in the unit requirement of metallized iron-bearing precipitator in the process of non-ferrous metals precipitation and reduces by 0.05 to 0.1% (abs.) the nickel and copper contents in the tailings of the given process. Technical solutions have been proposed for commercial introduction of the process.

Jan 1, 2004

By Nikhil Dhawan, Shrey Agrawal, Veeranjaneyulu Rayapudi

India’s steel vision of 2030 requires a huge amount of quality iron ore. The utilization of low-grade iron ores such as banded iron ores will play an important role to achieve the same production. The absence of alumina impurities in the banded hematite jasper (BHJ) ore provides it an edge over other low-grade iron ores. The conventional beneficiation techniques such as magnetic separation and washing were found to be ineffective to produce suitable feed (Fe ~ 60%) for the blast furnace. It was found that microwave exposure provides significant enrichment to the low-grade iron ore and can be used as a pretreatment step in the beneficiation of similar low-grade iron ores. The above study reveals that hematite phase is susceptible to microwave exposure which enhances the separation of iron values from impurities. Under optimum conditions, an iron-enriched concentrate with 61% Fe, 85% Fe recovery at 50% yield can be achieved from BHJ feed ~ 38% Fe. The pretreatment process for BHJ beneficiation includes only microwave exposure without any chemical additive and may prove economical and industrially feasible.

By K. Bachmann, M. Rudolph, U. A. Peuker, H. H. Duong, T. Heinig, T. Leißner, H. Schubert, Helmholtz-Institute Freiberg for Resource Technology, Technische Universität Bergakademie Freiberg

"Minerals can be liberated by random fracture of particles into smaller fragments or by detachment along phase boundaries. These two mechanisms represent borderline cases. When ores get comminuted the liberation of minerals is achieved to some extent by both mechanisms. This article describes a method to determine the extent of transgranular and intergranular fracture on surface exposure of minerals based on 2-dimensional liberation analysis.The approach uses the non-biased surface information like phase specific surface area (PSSA), phase specific free surface (PSFS) and phase specific locked surface (PSLS) of minerals and their change with comminution. The amount of transgranular and intergranular fracture on surface exposure can be calculated using the phase specific surface parameters.A sedimentary rock (apatite ore), an igneous rock (nepheline-syenite) and an artificial material (copper slags) were ground to different fineness. Based on the mineral liberation analysis (MLA) of feed and products, the extent of phase boundary fracture on the surface exposure of the minerals is studied.INTRODUCTIONMinerals can be liberated ether by comminution or by detachment (Gaudin, 1939). Liberation by comminution is a random fracture mechanism, which is not being influenced by ore texture, grain boundaries and mineral features (transgranular fracture). Liberation by detachment represents a fracture along grain boundaries (intergranular fracture). Random fracture often is named as the dominating mechanism for the liberation of ore minerals. This has been the basis to simplify models for liberation modelling (Barbery, 1991; King, 1979; Meloy, 1984) assuming that the probability of cracks moving along grain boundaries is zero. Thus, no interfacial area is lost during comminution."

Jan 1, 2016

By A Benedictus, A Butcher, J Wikstr÷m, B Lindblom, E Rutqvist

LKAB is a mining company situated in northern Scandinavia, manufacturing blast furnace- and direct-reduction pellets and sinter fines. Pellet development at LKAB comprises testing at laboratory and pilot scale. The LKAB Experimental Blast Furnace (EBF) is a unique test facility and an important tool in terms of product development and process research. For a better understanding of pellet behaviour in the blast furnace process, LKAB has started to use automated mineralogy for the characterisation and quantification of its iron ore products and pellets. A mineralogical evaluation of iron ore olivine pellets, taken from a test campaign in the EBF, has been performed. The studied materials were samples from excavated pellet layers through the entire EBF at different positions. A large number of iron ore pellets was analysed using a combination of automated mineralogy, using QEMSCAN«, and chemical analysis. Important information about the performance of pellets in the blast furnace process, such as a quantitative description of mineral and iron oxide alterations at different temperatures, Fe-reduction and alkali deposition, was obtained.

Jan 1, 2008

By D Maldonado

BlueScope Steel’s Port Kembla sinter machine underwent a major upgrade during mid-2009. The mixing and rolling drum (MRD) was thoroughly cleaned during the upgrade. Space factor measurements taken in October 2009 showed that the drum was operating in the cataract regime in the dry mixing section and the cascading regime in the rolling section, which is optimal for granulation. Sampling carried out during an entry into the MRD showed that both the Sauter mean diameter and the predicted bed voidage increase rapidly during wetting, and then decrease in the wet mixing section. In the rolling section, the granule properties remained constant untilthe drum discharge. Frozen particle analysis, using liquid nitrogen as the quenching agent, were carried out on material collected from the MRD discharge. The results, expressed as a Granulation Index, showed there had been a significant improvement in the granulating performance of the MRD following the upgrade. The plant studies were also complemented with laboratory scale experiments which aimed to optimise the granulation process. The effect of burnt lime on green feed permeability was quantifi ed using the laboratory scale drum at different moisture contents. A significant increase in permeability was apparent once the burnt lime dosing rates doubled from 1.1 - 2.2 per cent w/w (feed basis). The capacity of the burnt lime system at the sinter machine will be increased in order to benefi t from the expected higher permeability, permeability, which will enable the machine to sinter at deeper bed heights.

Jul 11, 2011

By KAGAN BENZESIK, OMUR CAN ODABAS, SELCUK KAN, Onuralp Yucel

In this study, domestic molybdenum disulfide (MoS2) concentrate was roasted in a chamber furnace and then in a rotary kiln. The behavior of the roasting process was examined in both furnaces, and which type of furnace is more advantageous to use in mass production was investigated. It is theoretically possible to roast in a chamber furnace, but a major problem was observed when the amount of concentrate was increased in the chamber-furnace experiments. The problem was solved by using a rotary kiln. This study improves the understanding of the roasting of  MoS2 concentrate and presents a different perspective to the industry, showing that rotary kilns can also be used for roasting.

By Onuralp Yücel, Kağan Benzeşik, Ömür Can Odabaş, Selçuk Kan

Extraction and processing constitute an important area in the metallurgy of molybdenum. Molybdenum trioxide (MoO3) production is one of the most important stages in molybdenum production. In this study, the effects of different furnace types on MoO3 production were investigated by using molybdenum concentrate as a raw material obtained during the enrichment of copper ores. Preliminary experiments have been made using a chamber type furnace, and a transition to a pilot-scale has been carried out with rotary kiln experiments. The effects of a different time and atmospheric conditions on MoO3 roasting kinetics were investigated by experimental studies conducted in the temperature range of 500–650°C. It was determined that the optimum temperature and time for sulfur (S) removal was 625°C and 180 min in the studies carried out in the rotary kiln, and it was determined that 0.61%S content was reached with an average removal efficiency of 98%. The activation energy in these sets was calculated as 89.519 kJ/mol.

May 3, 2021

By D. N. Esfahani, K. Khazen, M. Mohammadi

Electrowinning is one of the nickel recovery processes from solutions obtained from the leaching of nickel sources. Every year significant amounts of nickel products are used in various industrial processes and daily life, such as catalysts or batteries, which are a valuable source of nickel for recovery. Nickel purity is also very important in the electrowinning process, because the amount of impurities in nickel such as sulphur, if greater than 100 ppm, make it unsuitable for use in catalysts and plating. Because sulfur is intrinsic to the sulphate electrowinning system, we needed to investigate parameters that can affect the quality and purity of nickel. In this regard, experiments were performed in static and circulating electrowinning processes. A monitoring and circulation system was designed and built to measure voltage, current and temperature as well as to circulate the solution in the system at a specified rate. It was then observed that nickel ion concentration, pH, using the circulation system and additives, were factors affecting the purity and quality of nickel, and in the best case the amount of sulphur in nickel was below 100 ppm. Keywords: Nickel, electrowinning, sulphur impurity

Jan 1, 2020

By Michael S. Moats, Alexander Derrick

"The Winand Diagram was developed and has been used for decades to illustrate the interaction between polarization, mass transport and inhibition on the resulting structure of a metal electrodeposit. Recently, Adcock et al. criticized the Winand Diagram and developed their own structural diagram based on nucleation and plating overpotentials. Their work was based on zinc electrodeposition using a galvanostatic staircase method. This work explores the nucleation and plating overpotentials for copper electrodeposition using conditions typical for primary electrowinning and the galvanostatic staircase experimental technique. Additionally, the effects of organic additives and plating substrate on these overpotentials are reported.IntroductionThe control of electrodeposited structures is critically important to modem electrometallurgy operations to insure proper quality and efficient energy use. Electrodeposition of base metals for primary recovery (e.g. electrowinning or electrorefining), while similar to plating for decorative or device manufacturing, differs in the need to produce deposits that cover large areas and grow to significant thickness. Thus, controlling nucleation and particularly growth of electrodeposits is critically important for base metal electrometallurgical operations.The control of nucleation and growth on an industrial scale is most influenced by five parameters - current density, temperature, metal concentration, electrolyte agitation and additives. The effects of these parameters on electrodeposition are interrelated. To describe their effects on the type ofelectrodeposits generated and provide practitioners with a useful tool, Winand developed what is known as the Winand Diagram [1-2]. An adapted version of the Winand Diagram is shown in Figure 1.Winand characterized electrodeposits using Fischer's classification [3] and plotted the various deposit types versus inhibition on a vertical axis and the ratio of current density to bulk metal concentration on the horizontal axis. Inhibition intensity is a complex parameter and is still not well understood even though Fischer introduced the term in 1960 [4]. Often, inhibition intensity is simplified to equal the concentration of organic additive at the deposit surface and is related to the inverse of the exchange current density of the metal being deposited. The ratio of current density to bulk metal concentration is used to represent the ratio of crystallization overvoltage to mass transport of the depositing ion. As such i/iL could also be along the horizontal axis, where iL is the limiting current density of the electrodeposition reaction."

Jan 1, 2012

By Hakan Uyguçgil, Beril Bayraktar, Adnan Konuk

In mining, which is one of the industries with the highest risk of occupational accidents, a primary goal is to enhance safety through the thorough investigation of accidents using reliable methodologies. In this research, the data from 13,653 accidents reported in the Karadon Hard Coal Enterprise between 2000 and 2011 were analyzed and compared using the life-table and Kaplan-Meier methods. Accident records were classified and analyzed into four categories: environment-related, equipment-related, person-related and other accidents. Findings in terms of survival time indicate that environmentrelated and person-related accidents had the highest risk in Karadon, with equipment-related accidents having the lowest. This study established the reliability of using survival analysis methods to investigate occupational accidents in the mining sector. Given that environment-related and person-related accidents occur in a relatively short period, such as one year after starting work, it is recommended that research be done to improve workplace and occupational safety measures and broaden the training given to miners. Additionally, it is determined that increasing the use of automation and mechanization in underground coal mines, combined with developing a thorough equipment safety training program to raise awareness of the danger, can help prevent person-related occupational accidents caused by the interaction between equipment.

Feb 1, 2024