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By B Ganesia, H Sahupala

PT Freeport Indonesia is a copper-gold mine operation located in West Papua, Indonesia about 3500 km east of Jakarta. Current ore production is about 270 000 tpd, of which 30 000 tpd comes from underground. In the future, the production from underground will be gradually increased to reach a maximum of 115 000 tpd, as the Grasberg open pit production decreases. The current and future challenge for PT Freeport Indonesia is to fill the quota of underground miners, as Indonesia does not have a long culture of underground work. At present, there are only three active underground mines in Indonesia. The lack of underground skilled labour incited the company to develop its own skilled workforce. In the mean time, to overcome the shortage of personnel, the underground management had to find a way to improve the productivity. Since 21 May 1998, PT Freeport Indonesia Underground Mine has operated with the new roster of two rotating shifts a day, 11 hours per shift. The previous schedule consisted of three nine-hour shifts per day, six days a week, for a total of 26 working days in a month. This change was intended to increase the productivity of the miners. With the previous roster, studies determined that the effective working time was only seven hours per shift. The new roster produces an improvement of effective working hours to about nine hours per shift. As a result, total production has increased by 33 per cent and the utilisation of production equipment has increased by 16.5 per cent. This paper describes the background of the decision to change the work schedule, the study carried out to evaluate the benefits and drawbacks of the new shift roster, the challenges, and then compares the results for various parameters between the old schedule and the new one.

Jan 1, 2002

By W F. E Ouedraogo

This study data has been collected on a three-month period from November 2020 to January 2021 and based on three different pits: Vindaloo Main, Vindaloo Central and Bouere. Both pits having specific geotechnical and geological properties. Vindaloo Main, VIM, and Central, VIC, have the same mineral composition as volcanic tuff with felsic intrusion or monzodiorite, both rock mass is fractured with small joint. Geotechnically the uniaxial compressive strength UCS between 200 to 300 Mpa, Young’s Modulus 110 Gpa and Poisson’s ratio between 0.1 to 0.2. Bouere pit is basically made of volcanic tuff stock works as intrusive, UCS between 200 to 300 Mpa, Young’s Modulus 103 Gpa and Poisson’s ratio between 0.2 to 0.3. The first step of this study was to collect various data from mining operations around the drilling and blasting inputs. This was based around the different scenario of drilling parameters and the outcomes on the blasting, and how they impact load and haul operations and productivities of excavators from the heave to the last flitch. In most cases surface photos of the blast do not represent the overall fragmentation in the blast volume. Photos of the different flitches will not show only the effect of blast, as the loading operation generating more fragmentation by applying weight on the muck pile. Then the record of the different material uses for feeding. The last part of the analysis is the physical data from process plant such as particle size, throughput rate, both for the crusher and the mill, per pit and material and the specific Bond Work index (BWI). Fine particle quantity production is also a key point as is one direct indicator of milling performance. In overall, making link to BWI can influence at each stage of the mining to the processing operation. Drill and blast constitute a high cost in hard rock mining and trying to reduce these costs without an overview of all the integrated processes and context could end up by cost relocating to other activities in the process. However, the cost associated to size reduction builds exponentially as the particle size becomes smaller.

Jun 22, 2022

By M P. Sandy, R M. Stephenson

Portals to access underground mines are important infrastructure and their design requires careful consideration. Portals are generally expected to last for the life of the mine. Typically, the exposure of personnel and equipment is high, with many hundreds of movements through the portal per day. Consequently, the risk associated with geotechnical instability must be extremely low. Portals are often established from a boxcut. In areas where the weathering profile is well developed, the design and execution of the boxcut can involve significant effort, with the objective of minimizing the volume of the boxcut, whilst ensuring that conditions at the design depth are suitable for establishing a stable portal. Properly designed site investigations are a critical part of this process. Currently available portal design guidelines have not been updated for decades, however the equipment and ground support systems have changed significantly in recent years. Many mine portals have since been constructed in a relatively short time frame with success, often in challenging ground conditions using some of the more modern approaches to ground support. This is beneficial because delays in establishing a portal will generally delay other critical path activities, and lead to cost overruns.

Mar 15, 2021

By A Castleden, G Cavanough, M Kochanek, J Cunningham

ROES« is a proposed new mining system for underground hard rock mines. Ore is accessed from within a shaft, which is located close to or within the stope, and pitched either vertical or within approximately 20 degrees of vertical. The shaft is designed to exclude personnel entry so production drilling and explosive placement is done using remotely controlled or automated machines. Routine remotely controlled survey of the shaft, stope back and broken rock within the stope is typically done following each blast. The survey may include excavation geometry, rock fragmentation and geotechnical characteristics. Blastholes are surveyed before placement of explosives. This provides mine operators and engineers with real-time data, allowing them to monitor production performance and risk factors so that they can make rapid changes as required. ROES« is designed to apply to open stoping or sublevel caving situations either in disseminated, geologically defined, thick tabular or narrow vein orebodies. The technologies developed for ROES« will also have potential applications to block caving operations to reduce the risk of frozen ore and poor fragmentation. In a typical sublevel open stope application, ROES« will reduce the amount of stope-associated development by about half and therefore will allow ore to be brought on-stream sooner and at significantly reduced cost. Other savings are expected to flow from the centralisation of mining activities and operational data, reduction in mining fleet, reduction in ventilation requirements, improved occupational safety and reduced mine complexity. CSIRO and Orica Mining Services are developing the required technology and AMIRA is seeking sponsorship for a project to trial the mining method. This paper details the ROES« method, expected benefits and applications and includes typical stope and mining block designs and design requirements.

Jan 1, 2008

The Mineragraphic Section of the Council for Scientific and Industrial Research has had occasion from time to time to examine rocks, ores and concentrates from the Yatukoula goldfield, Fiji. The results of the examinations have been supplied as Mineragraphic Reports and have been supplementary to various investigations carried out by the mining companies on ore treatment, or by visiting geologists on the nature of the rocks and lodes. The presence of tellurides was determined in 1935, though incorrectly as nagyagite. The general absence of lead, except in traces, was soon afterwards discovered, and it came to be recognised as the mines were opened up that the chief telluride minerals on the field were sylvanite and native tellurium. Specimens of the tellurides have been provided from time to time by E. G. Theodore, Managing Director of the Emperor Mines Ltd., and of the Loloma (Fiji) Gold Mines N.L., and further material was recently obtained, as the result of a visit to the field at the invitation of Mr. Theodore.The aim of this paper is to describe the occurrence of the tellurides in these specimens. The work has been carried out as part of the programme of research of the Mineragraphic Section.THE VATUKOULA GOLDFIELDThe Emperor, Loloma and Dolphin mines are situated at Vatukoula, six miles, south of Tavua, on the north coast...

Jan 1, 1949

By Stevenson BG

The relevance of ore-dressing mineralogical investigations to developing and improving metallurgical flow-sheets is discussed and examples are given of the application of such studies to various types of ores and mill products (Au, Cu-Sn, Ni and Sn). The mineralogical investigations described illustrate (a) assessment of the feasibility of ore pre-concentration by heavy-media cyclone separation, (b) evaluation of the potential applicability of various metallurgical treatment processes to an ore, and (c) characterization of mill products to assess circuit efficiency and to guide circuit modifications.

Jan 1, 1978

By F F. Pitard

The optimisation of a metallurgical plant requires two kinds of sampling systems. The first provides samples to follow process changes, so in due time actions to maintain key parameters within pre-established specifications can be applied. The second provides composite samples at the end of a working shift to demonstrate that valuable constituents sent to the plant went to either a final concentrate or to the tailings in a logical, expected proportion. Contrary to what many experts may claim, these two kinds of sampling requirements are incompatible and cannot be fulfilled using the same sampling systems; this is because the required samples have completely different objectives. A process control sample is an instantaneous sample with increments taken at short intervals, and the objective is to know where the process is at any given time. Excellent accuracy is not a must, however good precision is recommended since a possible process correction may need to be made. Online analysers fed with in-stream stationary cutters or other kinds of in-stream or by-stream probes can do well for such a mission. A composite sample for metallurgical accounting with increments collected over a long period of time, for which excellent accuracy and good precision are both required, must be generated by sophisticated and extremely well-maintained cross-stream sampling stations. The use of process control sampling systems to achieve good metallurgical accounting has been promoted by several manufacturers of sampling equipment around the world; it is a grave mistake that is misleading top management and a practice that should be scrutinised and preferably eliminated. Furthermore, bias tests used to prove otherwise are often based on insufficient data to draw valid conclusions; a guideline is provided.CITATION:Pitard, F F, 2014. Sampling systems for process control and metallurgical accounting, in Proceedings Sampling 2014 , pp 25–32 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By Schon RW, Stephens CJ

The Whitsunday Volcanics occupy most of the offshore islands from the Whitsunday Group, southeastwards through the Cumberland and Northumberland Groups, possibly extending to the mainland adjacent to Shoalwater Bay, a distance of 370 km. Some of the islands of this group are granitic, but preliminary Rb-Sr data indicate these to represent Permo-Triassic basement. Cretaceous volcanism is interpreted to have occurred during initial rifting prior to the continental breakup of northeastern Australia and subsequent development of the Tasman Basin.The volcanics comprise mainly lithic ignimbrites, with local development of inter-bedded surge and bedded tuff, accretionary lapilli tuffs, lithic concentration zones, and lag deposits. Isolated fluidual rhyolite and dacite domes occur. The deposits are considered subaerially emplaced. A Rb-Sr isochron age for volcanism of 110 Ma is determined from new data. The total thickness of the volcanics is unknown, but a minimum thickness of 4-5 km on Whitsunday Is. is suggested. Eruptive centres are inferred to be distributed throughout the volcanic zone. The volcanics are cut by numerous, dominantly near N-S, dykes ranging from dolerite through to rhyolite in composition.Chemically, the volcanics and dykes exhibit a continuous range of compositions from basaltic andesite, through andesite, dacite, to rhyolite, with minor more alkalic compositions. Phenocryst mineralogy in the silicic rocks is mainly plagioclase, augite, and Fe-Ti oxides, with less frequent quartz and hornblende occurrence. Sr and Nd isoptic compositions for volcanics and dykes are close to mantle values. These data are tentatively interpreted in terms of a lower crustal magma arc source separated from the mantle only a geologically short time prior to Cretaceous magmatism.

Jan 1, 1990

By X Zheng, P Manton

Pebble recycle crushing circuit performance at Telfer has historically fallen significantly short of the design product P80 of 12 mm. An investigation was undertaken to evaluate the current pebble crusher circuit performance, quantify the optimum performance achievable with the existing circuit and examine the impact of pebble crusher performance on the overall grinding circuit throughput. The primary objective of this investigation was to develop an operating strategy that could consistently deliver the finest possible pebble crusher product to maximise the overall plant throughput.The pebble crusher specific energy (Wc) was proposed as a key control variable for pebble crusher operation based on the results of plant survey work. Over the range of pebble crusher specific energies encountered at Telfer, a strong linear relationship was found to exist between Wc and the crusher product size. This direct linear relationship between specific energy and crusher product size remained constant regardless of how the change in specific energy was generated, ie through changes to the crusher closed side setting (CSS), feed rate, liner profile or moisture content. Key findings for the Telfer pebble crushing circuit were: each 0.1 kWh/t change in Wc resulted in a 4.9 per cent to 6.0 per cent change in plant throughput, each 1 mm change in pebble crusher CSS resulted in a 2.2 per cent to 2.6 per cent change in plant throughput, and 0.57 tonne of new feed was displaced for each tonne of crushed pebbles recycled to the semi-autogenous grinding (SAG) mill. The presence of an existing 3000 tonne pebble stockpile between the SAG mill and pebble crushers provides an opportunity to manipulate the feed rate to the pebble crushers independently of the SAG mill pebble production rate. This flexibility, along with excess pebble crushing capacity, enables the pebble crusher specific energy to be maximised the majority of the time. Pebble crusher specific energy has subsequently been incorporated as an online crusher control measure to assist in maximising plant throughput.

Jan 1, 2009

The Ore Reserve System implemented at Mount Isa for Mount Isa Mines Limited is a comprehensive' computer system designed to process assay, geological, structural and survey data for Isa and Hilton Mines. This paper outlines the achievements of this system to date and by example, discusses the various reports and plotted output available. __ The impact of the ore reserve system particularly within the-Geology and Mine Plan ning Departments is reviewed in terms of new approaches to ore reserve calculations, evaluating the economics of various mining methods and reviewing preliminary stope designs. The compilation of metal distributions for both copper and lead orebodies at varying cut offs and reducing the involvement of skilled personnel in preparing non-standard plots of borehole paths are discussed. Options available through the system and their applications are outlined together with the planned future development of the system.

Jan 1, 1974

MIM Holdings Limited has acquired a reputation for the successful application of R&D to develop break-through technologies for the mining industry. The Isa Process tank-house technology has been licensed to copper refineries throughout the world, and almost 40 per cent of the worldÆs copper is refined using this technology. Isasmelt copper and lead smelting technology is either in use, or is currently being installed, by eight companies in eight countries around the world. Jameson Cell technology is widely used in the coal mining industry and increasingly in the base-metal industry. The IsaMills developed at Mount Isa and McArthur River made it possible to develop the McArthur River and George Fisher orebodies. This paper will address the need for innovation and then discuss the development of the IsaMill and Isasmelt technologies. It will conclude with some comments about why MIM has been so successful in developing such technologies.

Jan 1, 2002

By A Fitzpatrick

An integrated and dynamic water balance and water quality model for a proposed base metal mine has been created using the GoldSimÖ software package. The model was initially developed to address the water quality of the Tailings Management Facility pond and how pond discharge would potentially affect downstream water quality. However, due to changing project objectives, the modelling has expanded over time through an iterative process to encompass the full mine site and all receiving environment water quality. The model results have been used as part of the mine planning/design process but are also intended to be used for the environmental impact assessment and permitting process. The model has been built to allow for changes to input terms to be readily made as additional data becomes available. The model results serve as a prediction of water quality and the potential project impacts to the receiving environment water quality. This paper presents the process by which data from a wide variety of sources was used to construct the model and how the model results were used to guide development of a conceptual water management plan. In addition, the role of the model in establishing proposed discharge criteria will be highlighted. The model has been delivered as a fully functional application with the intent that the end-user can be other than the modeller, the development of this aspect shall also be covered. CITATION:Fitzpatrick, A, 2012. Predictive site-wide water quality modelling as a tool for mine planning and permitting - A recent Canadian example, in Proceedings Life-of-Mine 2012 , pp 71-78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By Windsor C. R, Thompson A, Bywater S

A new high tensile strength, steel cable, that may be grouted into boreholes has been developed for use as rode reinforcement. The manufacturing technique produces a birdcage pattern in which the cross section varies along the length of the cable. The load transfer from cement grouts to birdcage cables has been demonstrated in laboratory tests to be better than that of standard 15.2 mm diameter seven wire cables. The manufacturing process also allows for a wide range of capacities which may be specified by design engineers. The various birdcage cable configurations have been applied as rock reinforcement in a number of Australian underground and surface mines.

Jan 1, 1990

By Z Gao, D Liao, W Sun, S G. Pooley, J Wang, Z Shi, G Jing, S Ren, Q Chen

Yuanjing processing plant is a scheelite and wolframite plant in southern China. Water shortages and recent environmental regulations mean that the plant must reuse the wastewater that comes from the mining operation. This paper describes the efforts to reuse the mining and ore washing wastewater (MOW) in the processing plant. Initial attempts to reuse the MOW in the strong magnetic separation were unsuccessful because the magnetic media pack was seriously fouled by the micro-fine precipitate generated. The focus changed to reuse the MOW in the scheelite flotation circuit, which includes one roughing, one cleaning and three scavenging steps. Laboratory batch tests showed this would likely be successful because using MOW reliably improved the flotation performance in the laboratory tests. Then a 20 day industrial trial was run in the plant. The trial was very successful with the enrichment ratio of WO3 increasing from 17.4 to 23.6, while the recovery remained around 79.2 per cent. The industrial trial was so successful the company immediately adopted the new scheme, which has remained in use ever since. This technical solution not only alleviated serious water shortages, and satisfied environmental regulations but also improved the plant performance.

Aug 24, 2022

Proposals for engineering works in the River Dement in recent years have been made in the context of very little geological informat- ion. Breakage of the Tasman Bridge, forced a complete re-appraisal and collection of inform- ation in order to select a new site and predict problems. Seismic, magnetic and gravity methods foll- owed by drilling have allowed an assessment of the nature, thickness and distribution of mater- ials underlying the river bed. Key discoveries included recognition of low seismic velocity silts (1100 m/s) and a separate channel for the river since the Late Tertiary.

Jan 1, 1977

Evolutionary changes to the original sizer concept are mild when compared to those which have taken place in the engineering standards embodied in today's commercially available machines. This paper examines the principles of sizer operation and reviews the development trends in new applications for this unique screen type.

Jan 1, 1978

By N Pranoto, E Lawell, T Dean, M Grant

The Goonyella Riverside Mine is located 30 km north of Moranbah in Central Queensland, Australia. Recent mining activities have exposed the north–south striking Kenya and Zimbabwe thrust Faults. These faults vertically offset coal seams by up to 25 m and locally thicken coal packages through imbrication of coal seams. The presence of back-thrusts add to the geotechnical complexity of maintaining highwall stability. The Kenya and Zimbabwe Faults have provided multiple challenges to the mining operation, with an unplanned additional 240 kt of coal tonnes being mined from imbrication of coals seams or from the refinement to local scale geological models. These additional coal tonnes have been either identified during the mining of the coal seam or just prior to overburden removal above the coal seam. These faults can also negatively impacted highwall stability with highwall failures, lowering the overall slope angle for pit designs and increasing stand-off distances for hazardous highwall conditions. Unmanned Aerial Vehicles are used to scan exposed highwalls and enable geological mapping via high-quality 3D images. Measure while drill data from drill and blast rigs can provide local-scale intersections of the faults and coal seams. Mine Geologists utilise these and other data sets to create localised geological models refined position of the fault planes and coal seams. These models are utilised by relevant mine site teams to ensure the safe and efficient mining of coal around these faults.

Mar 22, 2022

By Mallett CW, Hammond RL

Geological maps of the Pacific Rim recently published by the Circum-Pacific Council for Energy and Mineral Resources have provided a useful perspective from which to view modern plate interaction and the evolution of modern fold belts. An important lesson from any study of modern plate interaction is that of the normality of change. The chaotic is more usual than the simple. Present day convergent margins with mixed characteristics are measures of this chaos. Indeed, the character of less than one third of the present length of the Pacific Rim can be ascribed to conventional models of plate interaction. Another lesson is that of the great mobility of oceanic crust. Enormous areas of the Pacific may not be represented in future fold belts developed at convergent boundaries unless normal consumption processes are disrupted, and even then only by linear zones a few kilometres wide. The axes of divergent boundaries creating Pacific Ocean crust have been equally mobile, with new spreading sites taking over from older sites through time. Divergent boundaries, whether active or inactive, consist of oceanic crust, and may be wholly consumed at collision sites with convergent boundaries. Their only potential contributions to fold belt evolution are transforms and magmatic activity. It is this transform component that can provide us with a mechanism to explain the apparent contradiction of both compressional and extensional features occurring together in a developing fold belt. Reconstructions for the SW Pacific are used to demonstrate that the fold belts under construction during the last 4% (Jurassic- Recent) of geologic time have involved interaction between convergent, divergent, and transform boundaries. In the last 15% of earth history (Late Proterozoic-Recent), many enigmatic features of the geologic landscape in Eastern

Jan 1, 1987

By A A. Roberts, R F. Dewhirst

"Extensive literature surveys, research in the project environment and personal experiences both within and consulting to project teams have revealed some consistent ‘people factors’ that contribute most to ultimate project success. Outside of purely technical and business case issues, there are a small number of leadership characteristics – probably only ten – that if correctly applied can positively leverage a team’s impact on project success.Of the top seven project success characteristics that were consistently highly rated in a recent study, five of them were around leadership. The authors have focused on this topic, noting that good leaders need to display the following traits:passionate commitment to deliveryconsistent modelling and reinforcement of correct values and behaviourfocus on managing relationships well and energising teams and individualscarefully clarifying project vision from front-end loading stages onwardseffective decision making.Not every project manager can and does practise these behaviours all of the time, but being aware of them and receiving training or facilitation in improving their application of these skills can equip project managers with the essential tools to markedly improve their own performance and that of their teams.This paper draws upon experiences in the field and provides lessons – both good and bad – to illustrate. As well as examining leadership traits, the way in which a leader can establish, organise, motivate his or her team and ultimately lead them to success is examined. The paper shares methodologies that have been successfully used to track status within a team and generate appropriate recovery plans where required.In particular, the paper will examine a case study based on an amalgamation of real project issues in some challenging situations using virtual teams (ie physically distant teams located in different centres) to illustrate the importance of strong and positive leadership in achieving success across geographies, time zones and languages.CITATION:Roberts, A A and Dewhirst, R F, 2016. Leadership in projects – a recipe for success, in Proceedings Project Evaluation 2016, pp 49–58 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By A Guillen, J-P ChilFs

Most 3D geological modelling tools were designed for the needs of the oil industry or detailed mine planning and are not suited to the variety of situations encountered in other application domains. Moreover, the usual modelling tools are not able to quantify the uncertainty of the geometric models generated. The potential field method was designed to build 3D geological models from data available in geology and mineral exploration, namely the geological map and a digital terrain model (DTM), structural data, borehole data and interpretations of the geologist. This method considers a geological interface as a particular isosurface of a scalar field defined in the 3D space, called a potential field. The interpolation of that field, based on cokriging, provides surfaces that honour all the data. The 3D model and its parts are always consistent with the observations. New developments allow the covariance of the potential field to be identified from the structural data. This makes it possible to associate sensible cokriging standard deviations to the potential field estimates and to express the uncertainty of the geometric model. It also, for the first time, gives a statistically optimal, geologically sound way of interpolating geology, other than directly joining the dots as you do with CAD. Practical implementation issues for producing 3D geological models are presented: how to handle faults, how to honour borehole ends, how to take relationships between several interfaces into account, how to model thin beds over many kilometres, how to optimise lithological properties and how to integrate gravimetric and magnetic data. We describe all geology surfaces and volumes using implicit functions. These are then rendered onto the required sections, plans, etc. The estimation of orebody grades and tonnes, using an unbiased and optimal geostatistical technique, makes use of the stratigraphically bound 3D geology model. An application to the geological modelling of the Hamersley iron ore district, Australia, is briefly presented.

Jan 1, 2009