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By J Joy, A Bye, G V. Kizil

This paper presents an application of the newly developed risk-cost-benefit (RCB) framework to support risk management decisions for the selection of wall monitoring technologies at an open cut mine site. The RCB framework quantitatively assessed the risk of unstable slope-induced wall failure and its impact on both loss of life and coal recovery. The RCB framework was utilised in the selection of an optimum group of risk-controls to effectively manage the risk of wall failure to ensure safety and optimal production occurred. The RCB framework incorporates mathematical modules that integrated RCB calculations and risk-control effectiveness assessments to determine the risk reduction and financial impact of the examined safety initiatives.This paper provides an overview of the five-staged RCB framework, incorporating the RCB decision support tools, RCBGEN (Risk-Cost-Benefit Generator) and RCEMETHOD (Risk-Control Effectiveness Method), and demonstrates its application to slope stability risk management at the case study site. The RCB charts are designed to display a balance between risk, cost and benefit for easy interpretation by decision makers to support the objective selection of an optimum suite of risk-controls. The RCB analysis revealed that a combination of ævisual inspections, automatic extensometers and radarÆ for fast- and slow-wall failures with structure were sufficient to reduce the probability of loss of life (PLoL) to the æModerateÆ zone as defined by the Australian Geomechanics Society (AGS, 2007) for the case study site. The new framework presented in this paper provides a method to effectively determine the suitability of risk-controls and supports industry efforts to reduce risk to as low as reasonably practicable (ALARP).CITATION:Kizil, G V, Bye, A and Joy, J, 2012. Risk-cost-benefit analysis of early warning technologies impact for wall failure risk management in surface mines, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 55-64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By J Harris, P Kirsch, D Cliff, M Spinks, S Goater, D Sprott

Fires are a common and recurrent unwanted event in the operation of open pit mines. In most cases, the causes of events such as fires are already æknownÆ but are either overlooked or not fully addressed in planning. Ongoing rapid growth of the global mining industry is creating a scarcity of skilled personnel, and high turnover within operations. This contributes to loss of corporate memory in risk management activities. RISKGATE« is an online risk management system designed to support and assist in the analysis of priority unwanted events in Australian coal mining operations. Funded by the Australian Coal Association Research Program (ACARP), RISKGATE« is a knowledge management program that delivers best-practice controls for unwanted events and assists operations in staying abreast of emergent risks and threats. RISKGATE« content has been primarily developed from an association of industry experts, and enriched with input from additional academic and technological resources. In mining operations, RISKGATE« provides a continuum of knowledge and best practice for risk identification, assessment and management. RISKGATE« will assist companies in improving safety performance, operational efficiency, operating practice and training. Here we present the RISKGATE« prototype as developed in 2011 for Fires, with a case study presented for the initiating event Fires on Mobile Plant.CITATION:Harris, J, Sprott, D, Spinks, M, Cliff, D, Goater, S and Kirsch, P, 2012. RISKGATE« - A case study in application to fires on mobile plant, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 49-54 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By L Eriksson, D Penn, J Appelgren

Atlas Copco, a leading supplier of equipment and services to the mining and construction industries, is consistently pursuing its strategy to offer the most productive and economical solutions by continuously offering new innovative products. These are, in most cases, developed and tested in close cooperation with demanding end users before being officially launched on the international market. The demands for higher productivity and improved overall economy have resulted in systems for automation of the drilling cycle and also tools for integrating the drilling equipment to the production control system used by the customer. In terms of improving the blasted material quality, the company has placed emphasis on accuracy in the drilling process and documenting what has been drilled. By applying state of the art technology to the common automation platform, developed for the surface drilling market, major steps in improving overall drilling productivity and blasting performance have been achieved. This paper will give some examples derived from the latest development of solutions for the companyÆs surface drilling products.CITATION:Appelgren, J, Eriksson, E and Penn, D, 2012. Rotary drilling automation increasing operator productivity and drilling quality, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 13-18 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By R Goater, P Kirsch, S Goater, I Goater

With staff productivity and retention a crucial factor in the longevity of AustraliaÆs mining industry, some mining companies are increasing their focus on the health and well-being of their people, to minimise the risks of deteriorating health in an ageing workforce. Many of AustraliaÆs mining operations rely heavily on long distance commuter (LDC) rosters, which are argued to have a significant impact upon worker health, wellbeing and lifestyle choices. The potential impact of workforce health on mine safety performance, efficiency and operating practice is an interesting additional line of enquiry. Food choice, exercise and recreation initiatives offer living and working conditions that æempower healthy choicesÆ in the shift worker community, but do not guarantee improved worker wellbeing. This paper explores first-hand the experiences of one individual over two and a half years of employment at different mine sites, under different shift conditions and across different operating crews. Novel insights and recommendations concerning the LDC lifestyle are offered through integrating reflections on one individualÆs fly-in, fly-out (FIFO) experiences in open pit mining operations from personal, family, professional and academic perspectives.CITATION:Goater, S, Goater, R, Goater, I and Kirsch, P, 2012. This life of mine - Personal reflections on the well-being of the contracted fly-in, fly-out workforce, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 31-40 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By P Hagan, S Campbell

A study was undertaken using various methodologies to determine the optimum loading and hauling configuration for different haul routes at Callide Mine, a coal mine located in central Queensland. The study involved development of an effective flat haul model that was used to estimate production rates in truck and shovel circuits that employ two excavators of differing capacities then Queuing Theory to construct a capacity constraint model for scheduling purposes to assist in truck allocation and finally a cost model to determine the most cost effective fleet configuration.The model was calibrated using haul road design and performance data of trucks and excavators currently in use at the mine. The study examined the effects of cycle time for different truck and excavator fleet configurations on production rate and costs.The study found haulage cost was directly related to cycle time while production rate reduced with cycle time. The study indicates the approach taken in combining a cost model with a capacity constraint model offers a simple and effective method of scheduling an optimum number of trucks in a haulage circuit.CITATION:Campbell, S and Hagan, P, 2012. Selection of an optimum truck and shovel fleet based on effective flat haul and capacity constraint modelling, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 19-26 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By T. Kumaresan

The Bayer process used for refining bauxite to smelting grade Alumina serves as the linchpin of the Aluminum production industry worldwide. Even though the process is well established, the presence of impurities in the liquor affects the quality of product and imposes a major economic cost on the industry. This review article focuses on the issues pertaining to Gibbsitic (Al2O3.3H2O) precipitation circuit. The comprehensive review provides a basic understanding of the aluminum trihydrate precipitation and agglomeration phenomena. Crystal growth rate and agglomeration play a significant role in determining the output PSD of agglomerates. Hence, the effect of certain thermodynamic and hydrodynamic parameters along with the impact of impurities (oxalates, aldols, acids etc.) and additives on hydrate growth has been reviewed.

Sep 1, 2012

By S. K. Chaudhuri

With a growing emphasis on maximizing the value by rapidly deploying it across their assets, mining firms are eager to identify any issues that may hinder such efforts and to refine their approaches to overcome them. As such a CDE vision can be considered realized when the following components are addressed and functioning as intended - People: the right resources working together and efficiently to achieve shared goals, Process: well-defined workflows mapped out for key value processes, Technology: availability of the correct tools and applications to increase efficiency in work execution and Locations: regional locations/ sites that need to be linked for collaboration and information exchange. For the above vision, an approach that considers the degree of interaction between the roles in metallurgy operations, mineral resource planning, mine engineering, plant operations, logistics and infrastructure, and which accounts for the current technology states across these groups to determine sub-processes where the impact of a CDE will be the most is critical. In effect, CDE is more about transforming an organization?s operational philosophy than a technology driven project. This paper examines the definition and components of a CDE in a mining context. Real-time operations co-ordination, maintenance interventions, production analysis and optimization processes are examined along with current state technologies and manual processes as candidates which are likely to result in most benefits from collaborative work processes. Finally, the paper examines technologies that can be used to further enable a collaborative working environment.

Sep 1, 2012

By B. Orberger

The fine fraction (< 2 mm) of the high grade Mn-ore from the world class Moanda deposit, Francevillan basin, in Gabon, contains up to 30 wt. % of manganese and about 0.4 wt. % phosphorous. A pilot study at laboratory scale integrating mineralogy and geochemistry before and after ultrasonic treatment was conducted on the fine fraction (< 2 mm) of oxidized Mn ore in order to reduce the phosphorous content and enrich this fraction in manganese. The fine fraction was dried, crushed at 2 cm and sieved at 2 mm. The two fractions (< 2 mm and 2 mm ? 2 cm) were investigated by X-ray diffraction and scanning electron microprobe ? electron dispersive spectroscopy analyses. Both fractions contain lithiophorite, cryptomelane and pyrolusite as Mn carrier, and goethite, muscovite, illite and quartz as contaminants. The Mn hydroxide nsutite was only found in the fraction 2mm ? 2 cm.The < 2 mm fraction is significantly richer in goethite, muscovite/illite, and quartz. Phosphorous carriers are mainly goethite (up to 2.8 wt. % P2O5), while the Mn minerals contain up to 0.8 wt. % P2O5. The Mn minerals are partly included in an agglomerate of goethite, muscovite/illite, and quartz. The < 2 mm fraction was treated by ultrasound for 30 s in normal water. Mineralogical and chemical analyses after ultrasound treatment showed that the Mn-minerals were largely liberated from the goethite-muscovite-illite agglomerate. Mass balance calculations show that after ultrasonic treatment the < 2 mm fraction was ? 50 % enriched in Mn and ?50 % impoverished in P.

Sep 1, 2012

By A. Pankewitz

The well-established on-line particle size analyzer OPUS manufactured by Sympatec GmbH, has been successfully implemented in several mining and industrial minerals project. OPUS monitors the particle size distribution in 31 fractions as well as the solid concentration in opaque and highly concentrated ore and mineral slurries on-line in real time e.g. behind mills or cyclones applying 31 ultrasonic frequencies for highest resolution. Ultrasonic extinction overcomes all limitations known from optical and mechanical systems like contamination, blockage and wear. OPUS measures slurries in their original state without any dilution, hence no extensive sampling procedure or sample conditioning is required thus no dilution errors occur. Due to the OPUS design and suitable algorithms entrained air bubbles do not affect the quality of analysis at all. The sensor covers particle size distributions from 0,01 to 3.000,00 µm and solid concentrations up to 70 % by volume and can be easily adapted to a number of production lines simultaneously. Jiangxi Copper?s Dexing Mine is one of the biggest copper mines in Asia and among the first users for OPUS on-line particle size and concentration analysis in mining industry. OPUS is connected to 2 process lines. Jiangxi Copper has implemented OPUS for into their central control system for the grinding & classifying circuit of one SAG mill and one ball mill. Analysis data and process control as well as optimization based on OPUS particle size and concentration measurements will be discussed Keywords: particle size analysis, ultrasonic extinction, concentration analysis, grinding control

Sep 1, 2012

By J. E. Gebhardt

Progress is reported on capturing the effects of gangue chemistry in the context of a comprehensive stockpile heap leach model for leaching copper sulfide ores, employing leading edge computational fluid dynamics (CFD) technology. The stockpile is a complex multi-phase process, comprising of a solid porous media, with complex fluid flow, gas and liquid phases, competing solid-liquid reactions, dissolution of minerals and transport through the heap. The model accounts for many of the challenging physical and chemical features of the heap, including transport and reactions kinetics for the important copper and iron sulfide minerals, ferrous oxidation, bacterial effects, thermal energy, acid and sulfate balances. In this contribution, the model has been extended to incorporate dissolution of various species from gangue reactions and precipitation of hydronium and potassium jarosite, ferric hydroxide, alunite, and gypsum. The effect of aeration on the simulation of a copper sulfide heap leach is provided as an example.

Sep 1, 2012

By Luis G. Bergh

Today, 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. In this work, a model of a rougher flotation circuit, based on operating variables and parameters fitted from industrial data, obtained in some previous work, is used to develop a set of logic rules in order to aid operating decisions. The simulator was first used to sensitize the effect of changing the froth depth profile on target variables, and then to find out the best profile to reject common disturbances coming into the plant. The flotation circuit simulator was redesigned to incorporate an expert system following the proposed control algorithm. Several tests were performed to evaluate the control responses to different correlated series of input variables, such as feed grade, tonnage, particle size distribution, and solid percentage. Control alternatives are discussed based on the circuit simulator. Keywords: modeling, industrial data, flotation control, mineral processing.

Sep 1, 2012

By R. Roufail

In this paper, the effect of different operating parameters of high speed stirred mill on the particle breakage mode is addressed. Morphological features of broken particles is investigated and related to the types of forces generated in the mill using Discrete Element Method (DEM). The stress intensities generated in the mill are varied by changing the agitator speed. The investigated agitator speeds were 1000, 1500, and 2000 revolution per minute (rpm). The minerals considered in this study are hard minerals (quartz) and soft, sulphide minerals (galena). The morphological features examined are roughness, roundness and elongation, which shed light on the mode of breakage during the grinding process. Particles that are rough, less round and elongated would imply that they broke via fracture, along their grain boundaries. On the other hand, the smooth, less elongated particles would mean breakage occurred across the grain, which is abrasion mod. DEM study complemented the understanding of particle breakage mechanism via tracking the types of forces applied on the particles. Normal forces imply compressive loading, which is presumed to impose fracture breakage along the grain boundaries, whereas tangential forces imply abrasion loading. Stirred mill grinding has been regarded as an attrition/abrasion process, whereas, this study showed that about 60% of total particles that are morphologically analyzed for both minerals were rough particles. Such an observation indicates that the fine product, which contain a significant amount of progeny from the coarse fractions are consistently broken via fracture. The morphology results agreed with the DEM findings, which indicated that the agitator speed, mineral type, and residence time would dictate the type and mode of particle breakage. Keywords: DEM, high speed stirred mill

Sep 1, 2012

By Mohsen Hashemzadehfini

Nowadays heap leaching has become established as a mineral processing technology for treatment of some low grade minerals such as copper, gold, and zinc, etc. Heap height, particle size, leach reagent consumption, and metal recovery are four important metallurgical parameters in a hydrometallurgical process like heap leaching. This paper investigated the effects of heap height and particle size on copper recovery as well as acid consumption. Three heap heights of 2, 4 and 6 meters and two particle size fractions of less than 25.4 mm and 50.8 mm were selected as variables in the experiments. The research results showed the inverse relation between heap height and copper recovery as well as acid consumption. Under given conditions, the copper recoveries of minus 25.4 mm ore are 78.63%, 66.27% and 52.88% higher than that of minus 50.8 mm samples for the heap heights of 2, 4, and 6 m, respectively. Both copper recovery and acid consumption increase with decreasing particle size. Keywords: heap leaching, heap height, particle size, acid consumption

Sep 1, 2012

By M. Wierink

The lifecycle of a resource, specifically a metal, is often depicted as circle from primary production from mining to minerals processing and via manufacturing and use to disposal and recycling. When a material is recycled, it is considered as saved energy compared to producing the material from primary source. This is, however, a simplified representation. At each step of the life cycle, there are changes in the quality of the material due to different materials chemical and physical interaction, phase transformations due to diffusion, radiation etc. Due to these physical and chemical phenomena there are losses of material, which as determined by thermodynamics are not recoverable within the life cycle. This can be considered as an increase embodied energy per mass unit of substance and loss exergy from the material cycle. With low cyclic loss, the material will remain in the recycling loop for a long time, while with high cyclic loss it will disappear fast. Where you put the material determines how fast it disappears from the resource cycle. In this research paper the phenomena of quality degradation of material and idea of increase of embodied energy and exergy loss within a resource cycles is portrayed. The cyclic nature of material states and transitions and energy consequences of material quality degradation as well as the parameters affecting the length of the time scales of the material cycles are described. Currently the cyclic embedded energy and the history of material is not taken under consideration in generic life cycle assessment. This easily results into a conclusion that lifetime of product is optimized only in terms of how much energy an appliance uses during its lifetime, while ignoring the loss of embedded energy due to the effects caused by the environs the material is subjected to during the cycle. Better description of the time properties of material give us a possibility to design toward optimum lifetime of products in terms of resource efficiency. Keywords: product lifetime, material lifetime, recycling, cyclic resource efficiency, material state, material quality, exergy, embodied energy

Sep 1, 2012

By V. V. Ramarao

Grinding and flotation operations deliver better-optimized performance when they are monitored and controlled in terms of the minerals they process rather than as elemental assays that we usually refer to. Mesh of grind (MoG), liberation, floatability, grade and recovery etc. are more directly related with the minerals and their characteristics rather than the elemental assays. Hence, online analyzers only provide the status for the grade and recovery of metals and not the direction for the enhanced performance. Central Research and Development Laboratory (CRDL) and Rampura Agucha Mine (RAM) mill section of Hindustan Zinc Limited (HZL) jointly undertook various survey campaigns in the grinding and flotation process streams. Grinding circuit surveys involved systematic collection of representative samples from different grinding circuit streams under stabilized conditions for monitoring particle size and process mineralogy details across individual grinding circuit. Flotation survey campaigns included study of fort-nightly / monthly composites of un-ground flotation feed, lead concentrate, lead tailing, zinc concentrate and final tailing samples for size distribution details in the 150 ? 38 micron range, chemical analysis and mineral characterization through optical microscope. This work details the investigations results and their implications on beneficiation performance. Grinding circuit survey campaigns supported the task for modifying the originally installed configuration of hydrocyclones, to limit recovery losses due to excess grinding of soft galena and related silver minerals. Flotation plant surveys helped in adjusting flotation circuit process parameters to reduce loss of liberated and floatable galena and sphalerite grains into their respective tailing streams. Keywords: grinding circuits, survey campaign, hydrocyclones, mineral liberation and locking, lead-zinc ore beneficiation operation

Sep 1, 2012

By B. A. Kutlin

29% of the total ore mined in the Russian Federation for copper production is finely disseminated copper-zinc-pyrite ores of the Ural Region. Physical and chemical characteristics of pyrite copper-zinc ores make for difficulties in obtaining high indices during processing. At present, the authors have elaborated the technology to improve the quality of copper concentrates up to 20.0% for the ones obtained during pyrite copper-zinc ore processing (based on the example of the ore mining and processing enterprise ?Uchalinsky GOK?, Russian Federation). There are examples of use of fair-sized pneumo-mechanical flotation machines by modernization of processing plants. Keywords: copper-zinc-pyrite ores, Ural region Russian, selective flotation, pneumo- mechanical flotation machines

Sep 1, 2012

By S. H. Morar

Froth stability is widely recognized as a key driver of flotation selectivity. It is well known that froth stability is affected by the type and quantity of surface active reagents present (frothers), and the concentration and hydrophobicity of solid particles present. While some studies have been performed on the effect of frothers on froth stability in three-phase systems and the hydrophobicity of particles present, very little work has been performed on the effect of solids loading on froth stability. This may be due to insufficiently robust measurement techniques. This paper investigates the use of a new machine vision measurement to measure solids loading, and the relationship between this measurement, bubble size, and bubble burst rate on the froth surface. Keywords: froth flotation, machine vision, solids loading

Sep 1, 2012

Taknar polymetal (Cu-Zn-Au-Ag-Pb) deposit and concentration flotation plant are located in the northeast of Iran. The flotation feed contains Chalcopyrite, sphalerite and pyrite with 4, 4 and 8 percent respectively. Cu and Zn contents are 1.26 and 3.5 present. Pyrite decreases the quality of base metal concentrates and increases the amount of sulfur compounds produced in the base metal extraction processes. Therefore, depression of pyrite is essential in the concentration of base metal sulfides by flotation. For flotation tests, 4 mixed collector systems, MIBC (20g/t), lime and tow depression systems (sodium cyanide (60g/t)-zinc sulphate and dextrin (300g/t)-zinc sulphate) were used as collector, frother, pH regulator and pyrite-sphalerite depressants in the chalcopyrite flotation stage, respectively, and SIPX, MIBC, lime and copper sulphate (as activator) were used in sphalerite flotation from first stage tailings. The results have shown that, sodium cyanide is a suitable depressant for pyrite and sphalerite in the first stage of flotation. Compared to dextrin as depressant, chalcopyrite recovery was decreased approximately 1.83%. In addition, when sodium cyanide was used as pyrite depressant, copper sulphate consumption raised approximately 90 g/t for activation of sphalerite. From Environment and HSE points of view, dextrin is natural, biodegradable, and non-toxic while cyanide is very high toxic. Keywords: sequential flotation, Cu-Zn massive sulphide, pyrite depressant, dextrin, cyanide

Sep 1, 2012

There are interactions between different minerals from the same ore, minerals and grinding media, and the electrochemical conditions present in the system. Grinding in steel rod and ball mills is a common practice in minerals processing. It is accepted, that the electrochemical interactions between the grinding media and minerals in a grinding mill, influence the corrosive wear of balls/rods and the surface properties of the ground minerals. A complex massive sulphide, Cu-Zn, TAKNAR, Iran, was used for all the experiments. The aim of this study was to investigate the effect of grinding media (dry or wet) on the pulp chemistry and recovery of Cu and Zn in bulk concentrate. 1100 g of ore samples were milled, and mill products with d80=85 and 75 micron in wet and dry grinding methods were produced. Rougher bulk flotation experiments were performed with 550g ore samples, at 30% solids. SIPX in conjunction with Aero238 in 1:2 ratio (48 g/t), was used as mixed collector system, and copper sulphate (200g/t) and MIBC (20 g/t) were employed as sphalerite activator and frother. Lime and High purity Oxygen gas were used for adjusting pH at 8.5 and aeration. The results showed that, more positive pulp potentials were measured when the feed had been ground in a dry environment, and the difference in pulp potentials between the dry and wet ground feed was approximately 250 mV after the grinding stage. In dry grinding method, the recovery of Cu and Zn increased approximately 5 and 10%, respectively. In addition, in dry ground samples, the volume of middling and coarse particles (+100 micron) were more and Dry ground flotation feed had better agreed with using a mixture of collectors. After using copper sulphate, pulp potential increased about 50 mV in dry and 75 mV in wet grinding methods. Keywords: grinding media, pulp potential, Cu-Zn massive sulphide, bulk flotation

Sep 1, 2012

By K. D. Mehta

Copper concentrate containing complex sulphides of Cu-Ni with 14.13% Cu and 10.04% Ni besides impurities such as 0.33% Co and 0.71% Mo, is not acceptable to the copper smelters due to the smelting problems. Selective bioleaching of nickel from the concentrate can be considered an an option to make it suitable for copper smelter. Effect of elemental sulphur and pyrite on the bioleaching of Ni and Co has been investigated using a mixed culture of Acidithiobacillus ferrooxidans (A.f.) and Acidithiobacillus thiooxidans (A.t.). Parameters such as pH, temperature, particles, size etc. were optimised to understand the role of additives in the bioleaching. With 2% S at 308K, 2.0 pH, 5% pulp density and 200µm size particles while shaking at 100 rpm, 79% Ni, 41% Co and 5% Cu were bioleached as compared to the leaching of 81% Ni and 45% Co in presence of 10 wt% pyrite in 60 days; 27% Ni, 24% Co and 4% Cu were recovered in sterile experiment. The selective dissolution of nickel and cobalt as compared to copper may be explained by galvanic interaction between chalcopyrite: pentlandite / pyrrhotite. Bioleaching was facilitated by strong oxidizing conditions due to higher Fe3+/Fe2+ ratio/redox potential (ESCE) as a result of improved interaction of minerals through biooxidation of sulphur and accelerated galvanic interaction by pyrite. The mechanism of selective leaching of Ni and Co was established by XRD phase identification.

Sep 1, 2012