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By J F. Colinet, G, J A. Zimmer, R J. Timko

It has long been known that ventilation is a cost-effective method to lower respirable dust concentrations in all types of mining applications. The National Institute for Occupational Safety and Health has been working on a number of different research techniques that use ventilation as a critical component to lower respirable dust levels at surface and metal/non-metal operations in the United States. This article presents five such research efforts. The first research area discusses how improving the ventilation flow patterns in an iron ore mill facility lowered respirable dust concentrations by 31 per cent throughout the primary grinding area. The second research area examines how respirable dust levels were lowered at a dimensional stone shop by using air cleaning units suspended from the ceiling. A third area discusses how improvements in ventilation at underground limestone mines lowered respirable dust concentrations. The fourth area examines how improvements in dust filtration and pressurisation systems significantly impacted the air quality in enclosed cabs of surface mining equipment. The last area presents a newly developed clothes cleaning technique. This technique uses an air spray manifold to blow dust from a workerÆs clothing in an enclosed booth, which confines the dust for capture and removal by a baghouse dust collector. These research areas represent an array of different control technologies to lower respirable dust concentrations. Ventilation is an integral part of these control technologies.

Jan 1, 2005

By B Lavin, R Sanford

This paper examines the application of Lean Manufacturing in a mining environment, based on experience within the Rio Tinto entities: Rio Tinto Aluminium, Northparkes Mines and Hunter Valley Operations. The three applications have tested the flexibility of the Lean methodology. Within Rio Tinto, Rio Tinto Aluminium was the first group to introduce Lean. The rollout began in late 2004. It was introduced firstly at Boyne Smelters, Gladstone, as a model site with the initial application in the Carbon Bake Furnace area. It was later extended to other sites including the Weipa Bauxite Mine. LeanÆs successful application within Rio Tinto Aluminium was in part responsible for its recent adoption by other Australian-based Rio Tinto business units including Northparkes Mines, a copper mining operation in Central New South Wales, and Hunter Valley Operations, a group of four coal mines in the Hunter Valley region of New South Wales. Lean is also being adopted by Rio Tinto Iron Ore. Rio Tinto Aluminium introduced Lean Manufacturing to complement an existing Six Sigma business improvement program and to achieve continuous improvement activities at a workplace level. Lean provides a similar level of rigour and discipline to Six Sigma but its application is everyday and for everyone, everywhere in the workplace. It is a valuable management tool. In a short time, Lean has achieved good and sometimes spectacular results improving productivity and efficiency at all sites, including our mining site. Within Rio Tinto Aluminium, it has also had beneficial impacts on our ability to develop and retain employees.

Jan 1, 2006

By Just GD, Gillies ADS

There is an increasing need for reliable and comparable coal resource data and it is necessary to standardize the traditional classification procedures by quantifying the three basic evaluation criteria of economic feasibility, geologic assurance and recovery. For well documented deposits, geostatistical methods can consider- ably improve classification quality. A geostatistically based algorithm for classifying coal resources within the current Queensland and New South Wales codes has been developed. Application of the method in classifying resources from a number of seams exhibiting different structural characteristics is assessed. The method is found to give classification results which closely reflect the error associated with an estimate of resource quantities based on current sampling densi- ties. It requires a careful geostatistical analysis with emphasis on geological awareness. Resource category restrictions must be arbi- trarily assigned and remain constant for all deposits being compared. Engineering judgement is needed and interpretation may be required with isolated and peripheral blocks.

Jan 1, 1987

By Hendon G. W, Carr F, Jiang Y

A vast majority of the operating longwall sections use shield-type face supports to provide ground control in the United States. As a co-operative research program between the University of Alabama (UA) and Jim Walter Resources, Inc.(JWR), a joint research program is underway to study interaction of shields with surrounding rock masses. A series of analyses on the response of shields are performed using monitored data at a longwall face in a deep coal mine. In this paper, various effects of parameters, such as leg pressure, setting load, developing load, maximum loading rate, pressure in capsule, and convergence between canopy and base, are discussed and recommended as stability indices. A microcomputer program is being developed for instantaneous interpretation of the shield monitored data, and for giving warnings of potential problems. The preliminary results define the effects of the setting load, developing load, and rate of developing load or leg closure rate. The objective of the study is to understand the shield characteristics and their interaction with surrounding strata in real time, then develop a reliable program for maintaining longwall stability.

Jan 1, 1992

Coal mining ceased at Strongman Mine this year after 70 years of production. Underground mining finished in 2003 and opencast methods began in 1998. During the life of the mine, 8 million tonnes of coal was extracted from two underground mines and 1.2 million tonnes removed through opencast methods. Strongman Mine is within the Grey Coal Fields; various seams have been extracted from the Rewanui Coal Measures. Coal extracted was predominantly of thermal or semi-soft specifications and characterised by low sulphur and low ash.   The area has steep topography, high rainfall (>3000 mm/yr) and is particularly exposed to westerly quarter winds. Strongman 1 and 2 underground mines are located in the steep, narrow valley which leads to the Strongman Opencast at the top of the valley. Subsidence from underground mining combined with spontaneous combustion, has resulted in an underground fire which has had substantial surface effects. Opencast mining in the steep topography resulted in several landslides at the perimeters of the site. These factors, along with water management, topsoil management and erosion control have added to the complexity of rehabilitating the site.   Rehabilitation of the site is well underway, including infrastructure removal, final landform creation and revegetation of the Strongman Opencast footprint (~45 hectares). Some innovative methods of rehabilitation have been trialled. Successful trials such as helicopter-seeding and moss hydro-seeding on highwalls are now routinely used along with traditional revegetation practices. 18 hectares disturbed land has been replanted with 88 000 seedlings, and another 200 000 seedlings are scheduled for planting over the three years. Fire management is an ongoing challenge; however thermal photography shows a steady decrease in hot areas which have been contained by grout curtains.   Mine closure is some time away and will occur after all standards set by Solid Energy and regulatory bodies are achieved.

Jan 1, 2006

By B Bonfils, P Lois Morales, C Evans

One of the main challenges for current and future mining and processing methodologies is to understand the characteristics of the rock so that its behaviour in one or more parts of the mining process chain can be predicted. Features such as rock texture, mineralogy or border complexity between minerals control how the rock behaves from the processing plant through to the final products, including tailings disposal and thus can affect the feasibility of the project from technical, economic and environmental impact perspectives. Understanding how the mineralogy and texture of rock affect its behaviour in mineral processing is a demanding area of research and is essential knowledge in predicting the processability of complex ores in different stages. This study aims to demonstrate that different types of relevant information can be extracted from a range of currently available analytical methods. However, this information can be used in a complementary way for building a more comprehensive rock characterisation at the microscale and better-predicting ore processing characteristics from the intact rock through to tailing disposal. CITATION: Lois Morales, P, Evans, C and Bonfils, B, 2018. Multisource rock characterisation at microscale for a better understanding of processing characteristics, in Proceedings Complex Orebodies Conference 2018, pp 44–48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By S Hanrahan, S McLaughlin

A case study is presented that details the safety journey at a North American project involving two major contracts: a 1000 m shaft recovery and rehabilitation, and the development of a drainage gallery in a large open pit operation. In the early stages of the contracts, there were a number of incidents that created tension between the owner and contractor, which resulted in the contractor being placed on a final warning with almost imminent potential termination. As a result of this, it was agreed to initiate a focused safety recovery plan as a ‘last chance’.Over a period of two years, the engagement and consequent performance of the contractor was turned around, steadily working to set it up for success such that in one of the contract work areas, a record of ‘one year LTI (lost time injury) free’ was achieved. The journey involved the owner and the contractor teams working cohesively to educate all parties in the safety requirements and, most importantly, providing the context and understanding for certain requirements being put in place. Early on in the process, it was recognised that the owner team unknowingly was an impediment in that they did not fully understand the safety requirements and so was not able to lead the way for the contractor effectively. The journey to rectify the situation was supported and followed up by focused engagement with the project team, which generated a progressive improvement in a very challenging environment.In particular, the contractor turnaround was significant and of enough value for the contractor to ultimately export some of the safety systems from this site to other contract sites. This demonstrated the ultimate benefit of the contractor understanding and buying into a safety culture and system.CITATION:Hanrahan, S and McLaughlin, S, 2016. Winning the safety battle, in Proceedings International Mine Management Conference, pp 181-186 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By Thompson M

The humble gabion basket is to mine development what the light bulb and safety pin are to eir-ryday life. Gabions provide a flexible, easy to assemble and cost efficient solution for "101" mine and civil engineering development applications.In some instances gabion baskets are still efficiently in use after many years of faithful, maintenance-free service. In other situations, the baskets have been demolished or made redundant within days, either having served their temporary usefulness or negligently destroyed by the operator of heavy equipment. Either way, the gabion basket must surely rate among the top 10 cost efficient engineering construction materials.

Jan 1, 1994

By C Yeung, N Swa, D Gribble, R Reupana

BlastLiteÖ is a low density explosive developed by Dyno Nobel and has been in use at BHP Billiton Iron OreÆs Mt Whaleback Operation since March 2004. The Mt Whaleback Operation utilises BlastLite because it offers an attractive alternative to ANFO in soft to medium strength rock types. Its use also reduces the amount of liquid fuel oil consumed and is well aligned with BHP BillitonÆs corporate Energy Excellence initiatives to reduce greenhouse gas emissions. This paper presents the:results of characterisation work completed on-site as a fourth year mining engineering thesis, and application and benefits of the product at Mt Whaleback. One of the key features of low density products is that the detonation is non-ideal. That is, the explosive does not react fully in the detonation driving zone. This manifests itself in that the product is highly dependent on charge diameter and confinement conditions. Dyno Nobel has access to the Vixen suite of detonation codes for characterising the ideal and non-ideal behaviour of explosives. The objectives of this work were to use the Vixen_i code to characterise the detonation performance of BlastLite, in order to understand the role of the bulking agent and to allow modelling of the explosive. The detonation performance was established by detonating a series of unconfined charges at various diameters and measuring the velocity of detonation (VoD). The work program consisted of sourcing and preparing cardboard tubes of various diameters (80 mm to 305 mm). The tubes were loaded with explosive at the BHP Billiton Iron Ore Mt Whaleback test range and detonated one at a time. Over the past three years BlastLite has been used in various applications across the site. Initial findings illustrate that shovel productivity from BlastLite shots was comparable to the baseline ANFO blasts. The study results were also backed with visual inspection and feedback from shovel operators. A work program is currently in place to develop different blends of BlastLite and TITAN« BlastLite to tailor the explosives to various blasting applications. The trials at Mt Whaleback are leading to future opportunities of BHP BillitonÆs satellite orebodies.

Jan 1, 2007

By B R. Castley

Consumable materials used in mines are often transported to the working areas down shallow angle decline shafts, typically at anywhere between 10¦ and 30¦ to the horizontal. The winding equipment is usually a relatively small single-drum winder and the material is transported in one or more cars, running on rails in the decline. The winding rope is attached directly to the cars, which are mechanically coupled together. For small rock hoisting declines, the cars are replaced with hoppers or skips. The winder is normally of basic design, fitted with only the minimum required safety devices and very elementary brake control. Since these winders are not ælicensedÆ and are usually located in remote areas, the standard of maintenance on the installations is often poor, leading to frequent accidents, resulting in runaways, derailments and broken ropes. These problems can be overcome easily with the application of the rope haulage principle. When large volumes of ore have to be transported to surface, belt conveyors are used on shallow angle inclines, or high-capacity friction winders are used in vertical shafts. Conveyors are limited to inclines no steeper than 14¦ and vertical shafts with large friction or drum type winders are extremely capital-intensive. Rope haulage systems can be used on decline shafts where the inclination is too steep for belt conveyors and too shallow for conventional drum winders. Rope haulage systems also offer a variety of safety, technical and cost advantages over other winding and transport systems. This paper describes the adaptation of the rope haulage principle to modern requirements and, combined with 21st century electronic technology, explains how the principle can be used as an efficient, safe and practical solution to some problems associated with the transport of materials, personnel and ore in mines. The authors describe the designs, methods of operation, safety aspects, automated control, loading and unloading facilities of modern rope haulage systems used for transporting personnel, material and ore. This paper considers a variety of systems already designed for different applications, from small material-only installations to multi-purpose and large rock-hoisting systems with payloads as much as 180 t. It also describes in more detail, a material transporting system recently commissioned in South Africa.

Jan 1, 2005

By S Phinn, V Glenn, P McKenna, P D. Erskine, D Doley

The key goals for mine site rehabilitation require mine managers to demonstrate that rehabilitation is safe, stable, self-sustainable and non-polluting. Within this context, it is reasonable for stakeholders to expect that mine site rehabilitation is resilient to disturbance impacts such as fire and drought. However, mine managers actively avoid fire on rehabilitation; and as a result have limited understanding of fire behaviour on revegetated landforms, the long term implications for site stability and the potential risk to site relinquishment. An experimental fire that was conducted at the Curragh Mine site in May 2015, burnt 117 ha of 19- to 21-year old mine site rehabilitation, mimicking wildfire conditions and creating a mosaic of fire impacts across the landform. Using a combination of ground surveys and remote sensing assessments, we demonstrate that over a two year period, ecological metrics such as species richness, woody density and understorey biomass all recover to pre-fire levels for both grassland and open woodland areas. This is supported by WorldView-3 satellite imagery and the remote sensing assessment using the differenced Normalised Differenced Vegetation Index (dNDVI) which shows high regrowth within the burn area in 12- and 24-month image captures. The results suggest that within the recorded conditions, this site is resilient to fire impacts, and has the capacity to recover to pre-fire levels within the first two years following the fire.CITATION:McKenna, P, Erskine, P D, Phinn, S, Glenn, V and Doley, D, 2018. Measuring the recovery of coal mine rehabilitation following fire in Queensland using remote sensing and ground surveys, in Proceedings Life-of-Mine 2018, pp 141–146 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By S Wangchai, D B. Hastie, P W. Wypych, A P. Grima

Industries that handle and process ‘dusty’ ores are facing increasingly difficult challenges to ensure sustainable operation and development. Most existing dust-control measures treat only the symptoms of dust generation and do not deal with the root cause/s of the problem. Many of these methods are also relatively inefficient in terms of controlling dust emissions. This paper summarises the various existing options available for dust control and some of their features, advantages and disadvantages. It then describes some of the new technologies that are being researched, developed and employed to minimise dust emissions by addressing dustability or dustiness and the dust generation mechanisms found in industry. Recent research results and case studies are presented to demonstrate some interesting findings obtained from this work. With improved understanding and modelling of dust generation mechanisms and bulk material dustiness, it is possible to achieve a step-change improvement in the design, troubleshooting and application of more efficient dust-control technologies.CITATION:Wypych, P W, Hastie, D B, Wangchai, S and Grima, A P, 2015. Research and application of new dust control technologies for the iron ore industry, in Proceedings Iron Ore 2015, pp 529–536 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By D J. Clark, R F. Wright, M D. Goodz

The A1 Gold Mine is a Devonian-age narrow vein high-grade gold deposit located 115 km east of Melbourne. The mine operated almost continuously from 1861 to 1992 producing 442 334 ounces of gold (13.8 t) from 530 436 tonnes from primary gold ore tonnes processed at an average recovered grade of 25.9 g/t Au. The A1 dyke was attributed with a yield exceeding 620 000 ounces (19.3 t) of gold (including gold in alluvial and tailings deposits), and was renowned as one of VictoriaÆs premier mines paying considerable dividends. The orebody was principally in a diorite dyke bulge 150 m long, 45 m wide and 700 m deep and was mined via two vertical shafts. The mine site was closed in 1992 and the site was rehabilitated in 1999. In 2008 - 2009, a diamond drilling program identified various extensions to the host dyke lithology and to gold-bearing quartz vein filled fault zones over a 700 m strike length. The outcome of this study was the establishment of a mine geology corridor four times longer in strike length than the original 1970s model. This opens A1 dyke hosted deposit style to exploration outside the historical dyke bulge and provides exploration opportunity for all similar deposits. Construction of the first 3D geological model has developed new insights on the host rock diorite dyke system and identified various extensions to both host stratigraphy and to gold-bearing mineralised structures. Coarse visible gold in quartz vein mineralisation (>30 g/t Au) and medium-grade stockwork mineralisation (8 - 15 g/t Au) has been intersected within 100 m of the surface and up to 300 m along strike of the nearest historical underground workings. At depth it appears that the mineralisation is continuous with the main dyke body with consideration of minor rotation in the strike orientation and limited reverse thrust faulting showing maximum displacement of 10 - 20 m. Along the A1 mine corridor, between two and five parallel dykes are observed at different drill sections. The gold mineralisation is hosted mainly within the dyke rocks, but where the sedimentary rocks are intensely silicified or are xenolith rafts, the gold mineralisation continues across these sedimentary rock blocks. There has been inference to the role of silicified sedimentary rocks as a second ore host and a bounding material for inflections in fault and vein orientations. In the central 150 m long A1 mine dyke bulge, the extremities are demarcated by four to five parallel dyke fingers (referred to as apophyses) going both north and south. These apophyses are clearly observed both vertically and horizontally between levels No 4 and No 9. The dyke fingers entrap sedimentary rock xenoliths and collectively form the A1 dyke æcorridorÆ, which is quite uniform in overall width from the easternmost contact (footwall) to the westernmost contact (hanging wall). Dyke fingers were assumed to coalesce at depth into a single dyke, but recent drilling shows this feature to repeat in several positions with depth and along strike. Key observations are the relationship between gold grade and fracture density, alteration, sulfidation, host rock morphology û relation of contact shape and fault zones. These relationships allow for the classification of prospectivity indicators and geology as a guide to potential extensions of mineralised zones. Mining geology is contributing to the whole-of-mine life planning and development where decline path, stockpile and infrastructure positions are controlled by geology.

Jan 1, 2009

By Tamura S, Maekawa M, Nagai C, Deguchi M

Heavy fuel oil has been injected into blast furnaces in order to reduce the coke rate, to improve productivity and to control the furnace heat condition. However, in the first oil crisis at the end of 1973, it became necessary to develop an injection technique of new fuels into blast furnaces to reduce oil consumption. In Kobe Steel, Ltd., it was thought that the injection of a coal-oil mixture (COM) into blast furnaces could be developed in a shorter time than pulverised coal injection. The development of this technique was under- taken in 1974, and COM was injected through two tuyeres of the No.3 blast furnace at the Kobe works in 1977 and 1978. In addition, in order to study the combust- ibility of COM and the phenomena in the tuyere zone, the development of a gas sampling method was under- taken in 1975. In this paper, the results of the injection tests and gas sampling tests are reported.

Jan 1, 1981

By C R. Stanley, D Lawie

The measurement of error in assays collected as part of a mineral exploration program or mining operation, including errors introduced during sampling, sample preparation, or geochemical analysis, historically has been undertaken in a variety of ways. Different parameters have been used to describe the magnitude of relative error and each of these parameters is related to the standard measure of relative error, the coefficient of variation. Calculation of the coefficient of variation can be undertaken in a variety of ways; however, only one produces unbiased estimates of measurement error: the root mean square coefficient of variation calculated from the individual coefficients of variation. CITATION:Lawie, D and Stanley, C R, 2012. Average relative error in geochemical determinations - Clarification, calculation and a plea for consistency, in Proceedings Sampling 2012 , pp 181-184 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By S Hancock, B H. Brady, H Muhlhaus

The aims of this paper are to present the governing science, verify the performance and demonstrate the potential engineering applications of a computational simulator for in situ leach mining of non-ferrous minerals. Assuming that the target mineral is deposited either uniformly within rock matrixes (matrix-hosted) or on fracture walls (fracture-hosted), in situ leaching can be treated as reactive flow and transport in geological media (porous media for matrix-hosted ore deposits and fractured media for fracture-hosted ore deposits). Under this treatment, the processes of in situ leach mining for non-ferrous minerals can be quantified through several sets of equations and these coupled equations have been numerically solved. The computational simulator has been applied to the simulations of one-, two-, and three-dimensional in situ leaching cases. The computational simulator, together with laboratory and in situ leaching tests, can be used to:optimise the leaching chemistry; optimise the in situ scale mining operations; scale up the in situ scale test operation to a full-scale mining operation; and evaluate the post-mining environmental restoration plan.

Jan 1, 2000

By W Midgley, M Torok, I Canbulat, J Katupitiya, S Saydam, S Akdag

The green energy transition is expected to require a range of valuable minerals, which could be supplied through deep-sea polymetallic nodule mining. Deep-sea polymetallic nodules are mineral deposits with a composition well suited to produce lithium batteries, which are expected to be a necessary energy storage solution (Diouf and Pode, 2015; Paulikas et al, 2020) for the energy transition. By 2050 the annual demand for both cobalt and lithium is estimated to increase by around 450 per cent from 2018 levels (Hund et al, 2023), with the annual demand for nickel being greater than 2 million tons, and copper greater than 1 million tons. Polymetallic nodule mining is well positioned to provide these minerals in the near future. An intricate and comparatively unexplored ecosystem thrives within and surrounding the nodule fields (Smith et al, 2008). Deep-sea mining operations have the potential to disrupt and permanently damage this ecosystem through introduced pollution, artificial noise and light, and habitat destruction. Hence, there is a pressing need for new engineering and scientific endeavours to focus on developing new technologies to reduce any environmental impact from mining.

Sep 1, 2024

The Managalase area is remote and little visited by geologists or prospectors. Yet it holds the key to the tectonics and petrology of this part of Papua. The eastern Managalase plateau (M, Figure 1) lies between the Hydrographers andesite volcano (H) and Sesara shoshonite volcano (S) to the south of Popondetta on the Papua Peninsular. It contains over 30 small volcanic centres in an area of only 400 km2 . To the south and west lies the basic-utrabasic belt (B-UB) of the Morobe arc. This is the leading edge of oceanic plate obducted over the Owen Stanley Metamorphics during the lower Eocene time. To the east and southeast lies the Cape Vogel geosyncline where the western end of the Woodlark basin spreading centre enters mainland Papua. The extension of the spreading centre as a suture might pass as far as the southern margin of the Musa Coastal plain. A new pattern of plate tectonic motions has been determined by the global positioning system and the southern margin of the Woodlark plate has been redefined (Tregoning et al, 1998; Taylor, Goodliffe and Martinez, et al, 1999). The Managalase plateau is margined by two inferred faults. These outline a cusp protruding from the main basic-ultrabasic belt where these rocks are near the surface. The westerly arm of the cusp passes through the centres of the Hydrographers and Mount Lamington andesitic volcanoes. Mount Lamington overlies Quaternary alluvium and underlying Tertiary sediments (Arculus et al, 1983) but members of the basic-ultrabasic belt crop out on the southern flanks. The easterly arm of the cusp is an inferred shear zone (and ? fault) connecting up with the terminus of the suture on the Musa coastal plain. Movements on the two faults forming the cusp are thought to have produced the conjugate N-S, E-W faults on the plateau (Ruxton, 1966). To the east, and isolated, are the two large andesitic stratovolcanoes of Mounts Victory (V) and Trafalgar (T) which together form Cape Nelson. Mount Victory was last active in the 1890s. The Waiowa shoshonitic volcano explosion centres (W), last active in 1943 - 1944, lie near the suture adjacent to the actively rising Goropu mountains. Extension in these mountains is clearly demonstrated by the soil profiles being skeletal along a bounding fault and ageing uphill. The incision of small parallel ravines also dig deeper further upslope from the fault. To the south-east of Mount Suckling (K) the Dayman Dome is also an expanding mass. The Owen Stanley fault is parallel, and located to the south of the suture. The Mesozoic metamorphics form the backbone of the Papuan Peninsula. The intramontane Musa Trough is thought to date from the mid-Tertiary. At the eastern end of the trough Pleistocene and Recent ultrabasic breccias and alkali basalt crop out (Green, 1961).

Jan 1, 1999

By H Parra, D Zenteno

Fragmentation modelling has been in use in the mining industry for a long time; however, there are still some aspects to tackle with regard to its use for strategic/planning and day-to-day purposes.On one hand, an important amount of resources are allocated to the task of calibrating and validating a good fragmentation model. Nonetheless, errors during the implementation stage introduce uncertainty into the prediction.On the other hand, it is common practice in the mining industry to use only discrete values to represent the fragmentation from blasting (k20, k50, k80), which provides a biased interpretation of the situation as, for instance, the best and worst possible cases are not taken into account. This is particularly critical when a continuous improvement philosophy has been adopted and modelling is used to either modify the drilling and blasting designs or plan ahead.It is well known that every site has particular conditions (rock mass, equipment, drilling and loading practices, among others) that often define unique trends in implementation. These trends can be captured using statistic and probabilistic techniques and then used as proxies for further analysis.This paper explores the potential of including implementation data in the form of probabilistic distributions into the Swebrec model to improve the performance of this engineering tool during the decision-making process.The fragmentation results of four designs were modelled using three different degrees of accuracy in the implementation for the burden, spacing and explosive column length.The data analysis showed that the probabilistic approach helps to achieve a broader perspective regarding the fragmentation that it is possible to obtain and the implications for the subsequent processes. The analysis also showed that the likelihood of producing similar fragmentation with different designs (involving different powder factors and costs associated) increases with the variability of the implementation.CITATION:Parra, H and Zenteno, D, 2015. Evaluating the inclusion of the implementation variability into fragmentation modelling, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 121–126 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By J P. Richards, M D. Johnston

The Porgera gold mine, located in the highlands of Papua New Guinea, produced 7.7 Moz of gold between 1990 and 1998. Reserves are estimated to be 12 Moz of Au. The deposit is associated with 6 Ma-old mafic alkalic intrusions emplaced at shallow levels into unconsolidated Jurassic and Cretaceous sediments, where they caused the formation of peperites. The mineralisation consists of an earlier base-metal-sulphide-rich stage with sericite-carbonate alteration (stage I), and a later phase represented by quartz-roscoelite veins (stage II). New styles of mineralisation and alteration have been recognised at depth in association with stage I. They consist of the assemblages magnetite-chalcopyrite-pyrrhotite and biotite-actinolite-anhydrite respectively. In addition, the recent recognition of adularia in some stage II veins (with roscoelite) confirms the similarity of this style of mineralisation with other adularia-sericite or low-sulphidation epithermal deposits.

Jan 1, 1999