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By M I. Pownceby, A Guiraud, S Purohit

Sticking and breakage of iron ore pellets during high temperature reduction can result in several operational challenges during shaft furnace ironmaking. With the shift to H2-based DRI processes and decreasing iron ore quality, this issue becomes more prominent. It is therefore important to understand how the iron ore chemistry and mineralogy affects the sticking and breakage of pellets inside the shaft furnace. This study provides a review of the mechanisms that lead to sticking and breakage of pellets inside the shaft furnace. The sticking index of pellets is related to the rate of metallic iron production as well as the precipitation morphology of product iron. Sticking of pellets is also enhanced by the formation of low-melting slag phases. The breakage of pellets inside the shaft furnace is often associated with the mechanical load of burden and pellet swelling, which is caused due to iron whisker or protruded iron formation. This paper investigates how the composition of iron ore, particularly the presence of different impurity oxides such as SiO2, Al2O3, MgO, CaO and alkali oxides in the pellets, influences the sticking and swelling indices. The effect of ore mineralogy on these adverse behaviours is also discussed.

Sep 18, 2023

By T O Aspinall

The Australian mineral industry involves a diverse range of expertise and skills. Within that, the mining industry, representing mine planning, mine management and equipment operation, has capital intensive, high productivity equipment and a small but skilled workforce. Continuing education for all personnel in the workforce after formal school courses will be an important contribution towards improving competitiveness. The non-tertiary sector represents a significant proportion of the workforce and requires as much attention as the tertiary educated group. Competency Based Training is now being developed for the mining industry in Australia under the National Training Board and the mining industry is well represented in establishing standards and curriculum. TAFE is a major source of accredited courses but some mining companies are also developing internal courses not necessarily for external accreditation. Articulation of such accredited courses to tertiary mining engineering courses has been considered. The education and training of equipment operators through continuing education requires attention to operating skills, an understanding of the productivity factors under the direct influence of the operator and providing product quality to the customer. The education and training of mining engineers has been widely covered and continuing close involvement of the mining industry is required to ensure well balanced courses in technical and interpersonal skills as well as motivation to continue learning for life. Postgraduate research is a part of continuing education but the mining industry has to continually address the adequate recognition of post-graduate qualifications for the increased technical or management expertise and the development of better analytical and problem solving skills which can be directed towards improving competitiveness. More attention has to be paid to providing adequate financial incentives to attract suitable students, particularly after attaining some experience, and to address their professional career path with a company so they are not significantly disadvantaged by undertaking post-graduate studies. The Chartered Professional Engineer status as provided by The Institution of Engineers, Australia to qualified candidates is being considered by The Australasian Institute of Mining and Metallurgy as a further recognition of a member's specific expertise and competence in mining and metallurgical engineering. Continuing education plays a major part in the maintenance of the expertise and competence required for a professional engineer to develop and also to retain chartered status. Continuing education will be a significant part of the education and training of all the mining workforce towards improving the competitiveness of the mining industry. The major challenges will be the motivation of all towards lifelong learning and the integration of the various programs towards providing the opportunity for a steady and satisfying career progression.

Jan 1, 1994

By J E. Everett

An essential requirement of product quality control in the mining industry is to be able to reliably predict key quality properties of finished product from the data available before the extraction of the ore. From a production viewpoint, the unit of data collection is generally the input and output data set for each shift of crusher production, but could be any period where mine precrusher data can be reliably matched with product data.This paper demonstrates that linear regression models can be used to predict crush grades from blast grades, even where the crush material is blended from multiple sources or pits for each of which differing regression models might apply. The advantage of using increasingly complex regressions models to match the available data to give increasingly more powerful models is examined. The best model for any application will be a balance between required predictability, available data and the business’ tolerance for complex models.The regression modelling approach has several advantages over the more classic method of run-of-mine (ROM) crusher trials, which will be discussed.The models can use any predictor variable such as grade, geotype and in situ density provided the preextraction data set can be reliably matched with post-crusher data and is significant as a predictor. The models have been used extensively in the generation of the daily crusher plan with the aim of maintaining finished product grade. This approach has also been used associated with exploration drilling and long-term planning.It is acknowledged that there are inherent problems in fitting lump and fines grade to a linear model. However, these problems are minor when they are used for interpolation within the window spanned by the shift blend records used to produce the model. This paper discusses some of the issues limiting linear regression models in this application, and suggests methods enabling consistent models to be formulated

Sep 5, 2011

By A R. Bye

The mining industry is facing some key challenges that provide a compelling case for geometallurgy initiatives. Over the last 30 years, the average grade of Australian orebodies being mined has halved while the waste removed to access the minerals has more than doubled. In the last eight years, the industry’s energy consumption has increased 70 per cent while multi-factored productivity has fallen 24 per cent. The paper documents a broad range of industry case studies which demonstrate strategies for gaining value from geometallurgy.The mining industry constantly faces the key questions of how significant ore variability is on mine valuation and how would knowledge of the variability change the mining schedule, mine to mill design and operation. Using case studies the paper describes the methods used for incorporating mineral extraction attributes into orebody models and their technical integration into daily operation as well as mine planning optimisation. While pit optimisation from a fully attributed geometallurgical model highlights areas of opportunity and risk it is shown that during the scheduling phase of mine planning that significant value can be added. The benefits from these projects included reducing geotechnical and environmental risk, improving mine to mill performance, option analysis and quantified cash flow risk. There is growing acceptance within the minerals industry that ‘realistically assumed modifying factors’ defined by a competent person/s are not sufficient to mitigate the risk of funding mining ventures. Geometallurgy is moving away from factored ore reserves to data-rich block models providing reliable information for mining, metallurgical and environmental considerations.

Sep 5, 2011

By J Foster

The Lanfranchi Nickel mine is located approximately 48 km south of Kambalda in Western Australia. Mining first commenced in the mid-1970s under the previous owner, Western Mining Corporation Ltd. After two years on care and maintenance, Panoramic Resources (previously known as Sally Malay Mining Ltd) purchased the operation in November 2004. The site currently produces approximately 10?000 tonnes of nickel metal annually from approximately 430?000 tonnes of ore. The Ore is mined from four main orebodies; Deacon, Helmut South, Lanfranchi and Schmitz. The Helmut South orebody is situated approximately 790 m below surface and extends to a resource depth of 940 m. Horizontal thickness of the orebody ranges from 10 m to 45 m in width, with the average being 30 m. Previous mining at the Lanfranchi operations specifically the Helmut orebody, had a history of seismic activity. When Panoramic Resources acquired the operation it was decided that seismicity was going to be an issue and therefore a mining method needed to be selected that could effectively manage this potential risk. The dip of the orebody is quite shallow at 45º, with a 30º plunge to the south . The hanging-wall comprises of very weak ultramafics. Due to these factors the orebody posed several mining challenges. To safely and effectively mine the Helmut South orebody in the Lanfranchi Nickel mine, underhand cut and fill mining was selected as the most appropriate mining method. Paste fill comprising of cemented gold tailings was the backfill of choice. This paper is intended to convey some of the key learnings from the use of a mining method that has not been commonly practiced in Australia.

Mar 21, 2011

By Gillies A. D S

Rail, port and shipping charges represent 30 to 50 per cent of landed costs for Australian coal mines selling to Asia. This proportion is higher for sales to Europe, yet it is in Europe where Australian producers are aiming for increased market share. The landed cost of coal to the international customer is the key parameter which determines market competitiveness. The objective of this study is to examine Australian export coal competitiveness in terms of transport distance. The approach used examines world coking coal and steaming coal production and the transport distances between major exporting regions and importing countries. Reference is made to the importance of land transport costs and a comparative approach for emphasising the relative magnitude of this factor is developed. Models developed are examined in terms of Australia's exports and a conclusion is reached that a reduction in rail freight costs would be an effective measure for improving the competitiveness of Australia's coal industry.

Jan 1, 1994

By C F. Stokes

The Trident Gold Deposit has been successfully developed by Alacer Gold (formerly Avoca Resources Limited) into a 1.3 Mt/a operation in the space of four years from discovery to first gold pour (2008). The current in situ Resource for Trident is estimated to be 5 900 000 t @ 5.0 g/t for 940 000 ounces at a cut-off of 1 g/t or 2 g/t depending on ore style. Production to date (Alacer and previous owners) is in excess of 500 000 ounces. The deposit lies towards the southern end of the Norseman-Wiluna Greenstone Belt in the Archaean Yilgarn Craton, where it is centred on the historical Higginsville Mining Centre, midway between the world class gold centres of St Ives (+15 Moz) and Norseman (+6.5 Moz). Trident is hosted primarily within a thick, weakly differentiated gabbro with subordinate mafic and ultramafic lithologies and comprises a series of north-northeast trending, shallowly north plunging ore zones. The deposit comprises two main mineralisation styles; large wallrock-hosted ore-zones comprising sigmoidal quartz tensional vein arrays and associated metasomatic wall rock alteration (Eastern Zone, Western Zone and Apollo) hosted exclusively within the gabbro; and thin, lode-style, nuggety laminated quartz veins (Athena and Artemis) that formed primarily at sheared lithological contacts between the various mafic and ultramafic lithologies. The initial interpretation of the Trident Deposit was based on steeply-dipping structures controlling the zones of mineralisation, with much of the targeting and drill-testing aimed at this style of orebody. Subsequent exposure of the orebodies has identified a series of shallow-east dipping mineralised systems (interpreted to be large reverse shears) that at their intersection with the steep-dipping structures cause significant gold enrichment. It is postulated that both orientations are primary fluid pathways with the intersection between the two resulting in zones with significantly high concentrations of gold mineralisation (in excess of 300 000 ounces). This new understanding on ore controls at Trident has identified that the thin lode-style shear-hosted laminated veins are continuous for over 1700 m along strike as they step en echelon down-plunge. In addition, a repetition and periodicity to the intersection between these steep dipping lode-style systems and the shallow-dipping mineralised zones (estimated to be 700 - 900 m down-plunge) has been identified which has considerably increased the down-plunge potential of the Trident Deposit.

Aug 22, 2011

By N Boughen

This paper synthesises the findings of five studies undertaken by the CSIRO Wealth from Oceans Flagship in 2009-10. This research explores the concerns, expectations, and information needs of a range of stakeholders, (ie government, seafloor exploration and mining industry, other marine industries, environmental non-government organisations (NGOs), community members) in relation to the possible exploration and mining of minerals and aggregates from the seafloor, as well as the conditions for meaningful engagement with communities regarding seafloor exploration and mining (SEM) activities. The SEM industry has been described as the ‘next minerals frontier’, as incentives to explore and mine seafloor resources increase because of diminishing reserves of easily accessible onshore mineral and aggregate deposits. However, the conditions (if any) under which SEM would be acceptable to stakeholders (notably the public and regulators) have not been established. This work seeks to address this gap and ascertain the levels at which potential environmental and social impacts become unacceptable to those stakeholders. The research follows an earlier phase of studies undertaken in 2006 - 2008 that: identified the opportunities and barriers to the development of SEM in Australia, took the first step towards understanding the public and political contexts surrounding the industry, and mapped the positions of key stakeholders and captured their major issues and concerns. Together, these two phases of research confirm that environmental concerns dominate stakeholders’ responses to the idea of an expanded industry. However, the most recent phase of research has also found that, similar to current onshore scenarios, reservations due to environmental concerns do not completely outweigh social and economic objectives. This is provided stakeholders feel confident that there are systems in place (regulatory frameworks, watchdogs, independent research, and stakeholder consultation) to ensure that all interests are protected. When making decisions about the social acceptability of potential seafloor mining, stakeholders favour a precautionary approach, supported by rigorous scientific analysis of the potential environmental impacts, transparent and socially responsive management processes, and meaningful stakeholder engagement. This paper outlines the details of these findings, which may also be relevant to understanding the social acceptability or ‘social licence to operate’ for other future mining scenarios featuring a new approach or technology.

Nov 22, 2011

By J Vann

Geometallurgy is inherently multidisciplinary and it gains its power to deliver improved outcomes for the minerals industry by bridging silos between disciplines. This cross-disciplinary approach unlocks value, identifies (and avoids) value destruction and provides a pathway to better implementation of an energy efficient and sustainable minerals industry. Despite this promise, we argue that the cross disciplinary approach also represents the greatest threat to the success of geometallurgy. Some key cross disciplinary issues identified are:Geometallurgy has so far evolved in the technical sphere, mainly by collaborations of geologists and metallurgists. Consequently, in many cases the business dimensions and value have not been incorporated. Financial and risk evaluation viewpoints need to be assimilated into the geometallurgical paradigm. In fact, until such measures are integrated into practices, the value cannot be fully demonstrated.The historical and current efforts on geometallurgy have been highly focused on improved sampling and measurement of geometallurgical properties or appropriate proxies. This work has been driven by professional and academic geologists and metallurgical engineers. It is notable that mining engineers (who are critical in the value delivery of geometallurgy through changed planning approaches) have so far been at the margins, or absent. The construction of valid three dimensional (3D) geometallurgical models raises some important organisational, mathematical and geostatistical considerations. The enhancement of resource models to account for geometallurgical aspects must be managed carefully if the full value of geometallurgical thinking is to be realised.The use of 3D geometallurgical models to change business decision making and practices is the real nub of the problem. We believe sophisticated scenario based evaluation methods are required if the potential impacts of spatial rock properties on processes further down the mining value chain are to be realistically evaluated. Such changed practices require ‘whole of value chain thinking’ to embed this change into the business in an ongoing way.Because profitable geometallurgy demands changed approaches to business decision-making and also organisation of the firm (radically changed in some cases), the senior executive viewpoint must be incorporated into the language and thinking of geometallurgy. This is unavoidable if the establishment of a geometallurgical approach to project evaluation, development and operation is to be successful and sustained.A powerful analogy for the problem faced by geometallurgy is the transformation of safety culture in the mining industry in the past 20 years. We argue that, as in the safety revolution, explicit models, cultural change and management of the ‘soft’ dimensions of the problem are pivotal to success of geometallurgy. In light of this, we propose a model (‘the Geomet Curve’) that gives a framework and pathway for geometallurgy in seven steps. The implications of this model for technical and organisational steps required at different stages are discussed.

Sep 5, 2011

Human-caused global warming has become the environmental cause celebre of the early 21st century. The strong warming alarmist camp currently includes the United Nations, most Western governments, most of the free press, many large corporations (including Enron, before it failed), the major churches, most scientific organisations and a large portion of general public opinion. This phalanx of support notwithstanding there is no scientific consensus as to the danger of human-induced climate change. There is, therefore, a strong conflict between the level of public alarm and its scientific justification. How can this be? In a democracy, the media serve to convey to the public the facts and hypotheses of climate change as provided by individual scientists, governmental and international research agencies, and NGO and other lobby groups. In general, the media have promulgated an alarmist cause for climate change; they have certainly failed to convey the degree of uncertainty that is characteristic of climate science, or a balanced summary of the many essential facts that are relevant to human causation. Climate change is as much a geological as it is a meteorological issue. Natural climate changes, both warmings and coolings, are indeed a societal hazard. We usually deal with geological hazards by providing civil defence authorities and the public with accurate, evidence-based, general information about events like earthquakes, volcanic eruptions, tsunamis and floods, and then by adapting to the effects when a damaging event occurs. As for other major natural disasters, the appropriate preparation for extreme climate events is to mitigate and manage the negative effects when they occur, and especially so for dangerous coolings. Attempting instead to æstop climate changeÆ by reducing human carbon dioxide emissions is a costly exercise of utter futility. Rational climate policies must be based on adaptation to dangerous change as and when it occurs, and irrespective of its sign or causation. The issue now is no longer climate change as such, the reality of which will always be with us. Rather, the issues are, first, the failure of the free press to inform the public about the true facts of human-caused climate change and of the dangers posed by natural climate change. And, second, the vested interests held by many of the groups of warming alarmists. These interests include not only the obvious commercial ones, but also the many scientists and science managers who have discounted or remained silent about the huge uncertainties of the human-caused global warming hypothesis because it suited them to do so. Public opinion will soon demand an explanation as to why experienced editors and hardened investigative journalists, worldwide, have melted before the blowtorch of self-induced guilt, political correctness and special interest expediency that marks the sophisms of global warming alarmists.

Jan 1, 2007

æSustainabilityÆ is one of those words that has gained more usage in popular discourse than in the dictionary. In fact it is not in many dictionaries at all. Typically, given this, it also seems to mean different things depending on whose lips it emerges from. It is now like a code word in that if people say it, you donÆt have to think about its meaning; it is just æthereÆ and is taken for granted. This is a problem for the mining industry as we are now using the term too and to be effective in what we do, we need to have a reality check and see how those outside who have views on us (æstakeholdersÆ maybe) use it. The core issue seems to be æsustainability of whatÆ: the industry?, a company?, the global environment?, particular ecosystems?, the community? At these levels, the term seems almost meaningless. If we do not even agree on what it is, at least broadly, our communication and possible partnerships for going forward will be difficult to say the least. One reference to æsustainÆ in my thesaurus is: æTo keep from failing during stress or difficultyÆ. This may be a clue to something approaching a common notion. I suggest that to use æsustainabilityÆ we make the following assumptions:that we are talking about human activity aimed at making a living that has an impact on the natural and social environment; that humans must make a living (though what this needs to include is problematic); that the impact of particular activities has been problematic to date and needs to be monitored, altered, stopped, etc; that there is stress on both social and natural environments; and that change can be effected in order that particular activities such as mining minimise their negative effects and maximise their positive. This is why we are taking part in sessions such as this one today. Two more initial observations: First, it strikes me that even with the above assumptions laid out, æsustainabilityÆ and æsustainable developmentÆ are too abstract and general as concepts. We have to break these high and mighty ideals down into workable, bite-size chunks, into practical ways of dealing with the world outside our sites and companies. Second, sustainability, on both sides of the fence, too often focuses on nature and environment as though they are independent of people and community. I would argue, perhaps provocatively, that sustainability is primarily a people issue and has to be tackled as such. I want to look at the overall climate for business today and how it has responded before I return to what we can and need to do as the mining industry to make æsustainabilityÆwork.

Jan 1, 2002

Study on Oil Agglomeration Flotation for Deinking

Sep 13, 2010

By E Kasai, T Nakamura, E Shibata

In the present study, formation of PCDD/Fs from carbon particles like æsootÆ, so called de novo synthesis, was experimentally simulated using the powder mixture of graphite and metallic chloride. Composite states of graphite and chloride particles were varied by the preliminary treatment, ie high-energy ball milling for different time or heating at different temperatures. These samples were subjected to the measurement of the rates of weight loss mainly due to the oxidation of carbon, the formation of absorbent organic chlorides (AOX) and the formation of PCDD/Fs at 300¦C. The amount of PCDD/Fs formation increased by applying certain pretreatments. Further, linear relationships were obtained among the formation rates of PCDD/Fs and AOX and the weight loss of sample. These results will give useful information to investigate the mechanism of PCDD/Fs formation from unburned combustible carbon and hydrocarbon in thermal processes.

Jan 1, 2002

The development and distribution of gold placers in Otago û Southland is related primarily to the evolution and architecture of three distinctly different drainage networks that developed during and since Gondwana breakup: +        Late-Gondwana û Pre-marine; +        Middle Tertiary Post-marine; and +        Modern. Late Gondwana û Pre-marine drainage was dominantly recti-linear and controlled by normal faults and sedimentary basins formed before or during Gondwana breakup. Placers formed dominantly in 2nd order transverse drainages with primary sources in their catchments. This drainage network was progressively destroyed by inundation and burial by marine strata during Late Cretaceous û Middle Tertiary marine transgression that ultimately covered most of New Zealand. Middle Tertiary Post-marine drainage evolved on and incised the newly emergent low-relief landscape during regional marine regression driven by development of the present plate boundary through South Island. Most of Central Otago was drained into Southland and to the southern coast via a large braided river system with an extensive network of tributaries in its Central Otago reach. East Otago was drained by several smaller systems. Placers formed dominantly in proximal and medial reaches of 1st and 2nd order drainages with primary or pre-existing placers in their catchments. This drainage network was destroyed by inundation and burial of the Central Otago reach of the major system by lacustrine strata following tectonic damning of its middle reach by range uplift and development of a lake complex that covered >5000km2 of Central Otago. The Modern drainage network evolved from the Middle Tertiary network through complex response, firstly to uplift of NW-trending and NE-trending ranges throughout the region since the Late Miocene, and secondly to the effects of major Pleistocene glacial advances in West Otago. Placers formed in alluvial fans at range margins, proximal and medial pre-glacial fluvial systems and glacial outwash sequences. Evolution of each of these drainage networks has been accompanied by widespread sedimentary recycling of alluvial gold from older to younger placers, augmented locally by input of first-cycle gold derived from erosion of primary sources in the repeatedly exhumed basement rocks.

Jan 1, 2006

By A Dennis, T Hunter, R Coleman

For metallurgical plant design, it is necessary to progress through successive phases of test work, piloting and process development before involving all the other engineering disciplines and “freezing” the process design criteria and flow sheet. This process usually relies upon the experience, skills and personal preferences of various technology providers, study and engineering entities, test work and metallurgical laboratories and, most importantly, the owner’s team and its operators. Current industry trends include lower grades, more complex orebodies, geometallurgy in defining orebody variation and design envelopes, more common “hybrid” plant processes and the market demands for more reliable, timely and predictable early plant performance.This paper will discuss interaction of these trends and provide guidelines for the level of detail and technical complexity required for a number of different “typical” examples. The paper will pay particular attention to the study definition level translated into the required detail and certainty needed by the overall process “owner” and original equipment manufacturer (OEM) equipment suppliers to ensure the best real plant performance. Some recent case studies will be discussed. In many projects, at a late stage of project definition, it has become common practice to undertake a “value engineering” phase. Although it could be argued that this should be undertaken earlier, it is largely driven by an overall need to reduce capex and “optimise” the perceived “fat” built into the project during the detailed design process. This value engineering can be very counterproductive to project timing and operational performance and warrants discussion.The paper is intended to promote discussion on a topic of wide interest. The authors’ diverse backgrounds and experiences are integral to the views in this paper.CITATION:Dennis, A, Coleman, R and Hunter, T, 2017. Critical process design considerations from test work to operations, in Proceedings MetPlant 2017, pp 12–30 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

Contemporary approaches to safety management appear to be failing short of meeting its mark in improving mine safety. This is evidenced by the high workers compensation, high incidence rates and fatalities. Evidence from high-risk and complex organisations points towards safety culture as being important in improving site safety. In more recent years resilience engineering has been touted as a new and innovative way of managing safety. This paper reviews and synthesises previous literature on safety culture and resilience engineering. It then highlights methods that can be used to measure safety culture and resilience engineering, and explores similarities and differences between complex organisations and gold mining to identify opportunities for more innovative approaches to improving safety in gold mining operations through safety culture and resilience engineering.

Aug 1, 2010

By I D. Gregson, A Gandhe, A S. Garcia, K M. MacAndrew

"Falls of ground still cause around one-third of all underground mining fatalities. The recent introduction of mechanised room and pillar working into Indian coalmines is an example of the application of new design by measurement and safety monitoring strategies, which can be used to reduce falls of ground risks in mines.Rock Mechanics Technology, now part of Golder Associates UK Ltd (Golder), is providing rock bolt support and pillar design services to the mines using a design by measurement approach. This involves in situ monitoring to confirm support and pillar designs and pillar extraction sequences.Site examples are given of the support designs determined and the monitoring programs undertaken for both design and safety.Routine safety monitoring of roof movement using telltales is also described. A new auto warning telltale has been developed specifically to warn of imminent caving as pillars are extracted.The approach used by Golder has played a major role in ensuring the success of these projects. As a consequence, mechanised room and pillar working is now firmly established in India, and wider application is planned to help meet future demand for coal.The experience confirms that the design by measurement method for this application has important advantages over conventional design approaches using analytical or empirical methods. Firstly, it measures the design performance or outcome rather than trying to calculate or predict it. Secondly, it provides the opportunity for the design to be adjusted to obtain the optimum outcome. Thirdly, it can do this at a local level, so that the support design can be matched to changing conditions to give the most cost-effective design. Finally, it incorporates long-term monitoring of support performance, again at a local level, so that subsequent change can be identified to enable corrective measures to be implemented in a timely manner and to ensure that ground control safety is maintained.CITATION:MacAndrew, K M, Garcia, A S, Gregson, I D and Gandhe, A, 2014. Application of design by measurement for support and pillar design in mechanised room and pillar coal mining in India, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference, pp 65–76 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 5, 2014

By P Moser, R Ivanova, F Ouchterlony

This paper describes model-scale bench blasts on mortar blocks with distorted drill hole patterns, done in 2013–2014 at the Montanuniversitaet Leoben. The main aim of the project is to see if the fragmentation from and the crack development behind blasts with and without drill hole deviations differ significantly.The dimensions of the test blocks were 660 × 280 × 210 mm (L × W × H). They were mounted inside a yoke that allows the blast waves to escape (see Figure 1). Three rows in each block were shot row by row with a nominal pattern of B × S = 70 × 95 mm. The same nominal delay 73 µs (ie 1 ms per m burden) between holes was used throughout. Blocks with holes of stochastic collar position errors (variations in burden or in burden and spacing but constant row volume) and systematically shifted collar positions (blasts with staggered pattern) were shot. The results were compared to reference blocks without collar deviations.Apart from the sieving analysis, the remaining bench faces were measured with a stereo-photogrammetric method and horizontal roughness profiles for each row were constructed. Sawing slabs from block remains after the third row and use of dye penetrant allowed the study of internal blast damage.The analysis showed that none of the changes in borehole collaring had a significant effect on the sieving curve (median). The sieving results confirm earlier findings though that the fragmentation gets finer with the number of rows shot, implying that blast damage from earlier rows has an influence on the blasting results. The tests demonstrated that the nequiv (equivalent n-value) has increased ten per cent by shooting staggered pattern and decreased by seven per cent by pattern with burden and spacing errors. For the rest of the patterns, the nequiv was roughly the same.The surface roughness investigation showed that a smooth surface was achieved by the staggered pattern. The other deviations patterns did not show a clear trend.The internal blast damage, which was measured in the remaining part of blocks, showed that out of eleven, four crack families seemed to be most affected by blasting. The comparison of the reference and distorted patterns showed that less cracks were apparent for the staggered pattern, ie less damage was introduced.CITATION:Ivanova, R, Ouchterlony, F and Moser, P, 2015. Influence of distorted blasthole patterns on fragmentation as well as roughness of, and blast damage behind, remaining bench face in model-scale blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 693–706 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

The creation of an accurate and precise enough database requires the collection of many representative samples, subsampling and assaying them without destroying their integrity. The selection and implementation of sampling protocols often lead to severe difficulties, making the unaware practitioner vulnerable to massive exploration, feasibility and operating failures. Therefore, there is no substitute for a good understanding of the Theory of Sampling (TOS). Either because of ignorance, or because of short-term economic reasons, failure to comply with many stringent conditions can be devastating for the validity of a feasibility study, leading to false evaluations, to the abandonment of a viable property, or to the exploitation of one that is not profitable. All these failures have something in common: insufficient duplicate sampling, subsampling and assaying were performed; very important, preliminary heterogeneity tests were never performed; for short-term economic reasons, poor sampling and subsampling protocols were selected, second-class sampling systems and weightometers were installed and poor preventive maintenance and cleaning were implemented;and sampling experts were called only when the project was obviously in trouble. The conclusion is clear: in due time, iterative auditing of sampling practices is an insurance policy against massive financial losses for the company involved. A complete, comprehensive 100 point checklist of sampling Quality Assurance and Quality Control is provided, so critically important details to ensure success are not forgotten.

Mar 1, 2010

Sampling protocols and metallurgical flow sheets should be designed to suit the style of mineralisation in question. In support, the a priori need for evaluation programs is the characterisation of the mineralisation type(s) and domain definition. The proportion and size of gold particles has a direct impact on the effectiveness of sampling protocols and metallurgical processes employed. Within the coarse- to-fi ne gold spectrum, the samplability of a deposit ranges from relatively simple for fine-grained disseminated particles, through to difficult for coarse gold mineralisation. Conversely, metallurgical processing may be relatively simple for coarse gold ore and more difficult for very fi ne gold ores. Most deposits contain a proportion of both particle size types. The nature of mineralisation, mineralogy and associated gold particle sizing can only be determined by preliminary sampling to facilitate testing. Mineralogical studies, focussing on ore mineralogy and gold particle deportment, size and distribution are required as part of wider paragenetic and geometallurgical investigations. This paper discusses key issues and presents a methodology for the determination of gold particle size in coarse gravity-gold ores to support sampling optimisation and which also contributes to metallurgical characterisation.

Aug 1, 2010