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By G J. Lyman, S A. Tittlemier

International regulations exist to manage the concentrations of mycotoxins such as Ochratoxin A (OTA) and deoxynivalenol (DON) in grains and prevent health risks from excessive exposure to OTA and DON. Since the permitted levels of these mycotoxins are very low (existing maximum levels are in the range of 5 ppb for OTA and 1–2 ppm for DON), sampling for these mycotoxins is potentially challenging. Given that the distribution of infected kernels in a consignment of wheat can be highly heterogeneous, detection by current sampling methods is subject to a high variance. Furthermore, the concentrations of mycotoxins in individual kernels vary over orders of magnitude, intensifying the heterogeneity of the bulk grain.In these circumstances, there is much interest in developing sampling plans that inform regulatory agencies, and mitigate the risk of misclassifying grain shipments as compliant or non-compliant within the global grain trade, when correctly implemented.Experimental data from laboratory and field studies describing individual wheat kernel concentrations of OTA and DON were combined with experimental data describing the variance due to the analytical methods used for OTA and DON to calculate the sampling distribution for wheat having various levels of contamination. This work has focused on quantifying the heterogeneity of samples at the point of submission for analysis and within subsequent sample preparation to arrive at total sampling distributions that include uncertainties due to the intrinsic heterogeneity and the analytical uncertainties. The sampling uncertainty that relates to the difference between the primary sample analysis and the true lot analysis is not included as it has been dealt with elsewhere.CITATION:Lyman, G J and Tittlemier, S A, 2017. The sampling characteristics of grains contaminated by mycotoxins, in Proceedings Eighth World Conference on Sampling and Blending , pp 281–294 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By R M. Anderson, S P. Pigdon

The production of stabilised backfill at mine sites commonly uses Portland cement as the binder. Calcined gypsum has cementing properties and is cheaper to produce than cement. This paper discusses the strength of fills stabilised with calcined gypsum. Laboratory tests were carried out on specimens prepared from tailings obtained from four different sites to allow for the wide variety of tailings found in practice. The results show that the gypsum-based fills can achieve a strength of 1 MPa using around two and a half to four times the corresponding amount of cement.

Jan 1, 1998

By L MacDonald, D Molver, D Pepper

Increasing contamination/impurity levels (including arsenic, antimony, mercury etc.) of concentrates is an issue of global commercial and health / environmental significance. With increasing environmental pressures at smelters, penalties for contaminants in concentrates continue to rise, accompanied by lower reject limits. There is a strong incentive for miners to investigate alternative means to remove contaminants in order to increase the value of complex ores and concentrates. This paper discusses the global problem of contamination in complex ores and concentrates, how the Toowong Process technology is a potential solution to this problem, and the opportunities this technology brings to the business of dealing with deleterious elements. CITATION: MacDonald, L, Molver, D and Pepper, D, 2018. The Toowong process for treatment of complex ores, in Proceedings Complex Orebodies Conference 2018, pp 119–121 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By Lawson F

A rotating disc geometry has been used to provide a uniformly accessible surface for a kinetic study of the cementation of the metals cadmium, lead and silver from dilute aqueous solutions. This work is an extension of studies carried out on the Cu/Zn and Cu/Fe systems for which the rection rate was found to be completely solution-phase mass-transfer controlled. When the amount of material deposited was greater than 0.2 to 0.4 mg/cm2 there was an apparent enhancement in e which is attributed to the formation of a roughened deposit. This same phenomeon was obseived in the Cu/Zn Cu/Fe systems. Again, the rate of reaction of each system investigated was found to be solution-phase mass ,..~sfer controlled.

Jan 1, 1970

The refractory industry in New Zealand is small, consisting of two main manufacturers - one at Huntly and the other at Kamo. Together these would have an annual refractory production of about 30 000 tonnes. The industries which use refractories include two steelworks, NewZealand Steel Limited and Pacific Steel Limited, the former is involved in continuous casting from sponge, iron and scrap steel and the latter is involved in ingot teaming from scrap steel and steel billets; One aluminium smelter, cement works, dairy companies, small foundries producing engineering requirements and many other small users. The New Zealand manufacturers produce refractories in thefire brick range, that is up to 50 per cent alumina content (ignited basis), based on indigenous raw materials and in the high alumina range up to 85 per cent alumina content (ignited basis) based on imported bauxites. All of the basic refractories high purity silica and high alumina low alkali refractories and many of the higher grade acid resisting refractories are imported.

Jan 1, 1976

The Permo-Triassic Bowen Basin developed during the final stages of the Tasman Orogenic Phase in eastern Australia. The basin has considerable economic value as a source of coal, natural gas and precious metals. The basin, which is of controversial origin, is preserved as a north-south trending, asymmetrical syncline bounded in places by faults. It is here interpreted as a retroarc foreland basin which developed on the landward (west) side of a continental arc associated with continent-ocean plate convergence. Initiation of the basin occurred via back-arc extension in Early Permian times, coincident with a phase of talc-alkaline arc volcanism. Early Permian, mostly marine sedimentation gave away to extensive coastal and alluvial plain depositional systems in Late Permian times, coincident with a resurgence of arc volcanism. Triassic sedimentation was almost entirely alluvial and coeval with westward propagation of thrust sheets from the eastern basin margin. Compressive tectonics climaxed in Middle to Late Triassic times, terminating sediment accumulation and uplifting the entire area.

Jan 1, 1990

By J E. Eberhardt

Ore sorting has long been used to raise the efficiency and thus lower the environmental impact of mineral processing operations. It was first instituted as hand sorting, according to a humanly perceived difference in the ore, but is now automated using large mechanical sorters in order to meet the high tonnage throughput required in most minerals processing applications. In the past, ore sorting was generally used as a niche processing route when other approaches failed, and in this context, consequential environmental benefits are often not the first consideration in adopting sorting. When applicable, ore sorting offers environmental benefits in reductions in fines waste, reagent usage and energy consumption in milling. Although there are significant opportunities for the use of ore sorting technology in many minerals processing operations, industry applications, to date, have been limited mainly to the processing of diamonds, magnesite, talc and uranium ores. This limitation has principally been due to a lack of suitable sensing technologies for a wide range of ore types. The authors report on a wide-ranging review of the automated sorting of mineral ores, and in particular, on methods for discrimination of ore characteristics prior to mechanical sorting.

Jan 1, 2002

By McGuckin P. H, Logan A. S

The BHP Minerals' Cannington silver-lead-zinc deposit is located approximately 190 km south-east of Mount Isa. The deposit, is hosted by Proterozoic rocks beneath a thin cover of younger sediments, and contains a total estimated resource of 45.3 million tonnes at 11.1 per cent lead, 4.4 per cent zinc and 500 g/t silver. The deposit is separated by faulting to form a shallow, lower grade Northern Zone and a deeper, higher grade Southern Zone (Roche, 1994). Contract development of an exploration decline to test mineralisation in the Southern Zone commenced with the excavation of a boxcut in August 1993. The complex variably deformed Proterozoic sequence interpreted from drill core and intersected in the exploration decline has required a high level of practical rock mechanics input to achieve: ò appropriate support designs, ò a high quality of installation, and ò required development advance schedules. The Norwegian Tunnelling Index (Q System) in conjunction with regular face mapping is used as an operating tool to assist in decision making for ground support. Line mapping, discontinuity analysis and wedge assessments are conducted routinely to optimise ground support requirements in the decline, intersections and all other underground excavations. Throughout the project, an emphasis has been placed on developing a strong working relationship with the contractor to achieve quality assurance program targets.

Jan 1, 1995

Exploration risk increases with time, due to a general decrease in prospectivity as the more accessible deposits are found, and be- cause of rising costs and demands due to an improving standard of living. Risk is separated into financial risk, which increases sharply at the development stage, and the risk of failure which is at its peak at the outset of exploration. Risk is also divided into internal and external factors; some of the latter cannot be offset, viz. the systematic overall risk for any enterprise. The recently emergent risk embodied in withdrawal of large areas from exploration access is discussed. An appeal is made for objective multiple land-use policies to be applied so that land remains available at reasonable cost and with appropriate environ- mental safeguard conditions. Risks specific to gold exploration are discussed. As gold now accounts for over 50% of all mineral exploration, and most other metals are depressed, any sharp decline in gold will have grave effects on the ex- ploration industry. Gold exploration will become more difficult and expensive in about five years, after most of the readily accessible deposits in Australia are found. Government's role is important in pro- viding stability and basic data at reasonable cost. Exploration for specific minerals or of particular areas could be stimulated by extending the 150%.tax deductibility of R & D to aspects of exploration of strategic im- portance, particularly in the event of a downturn. Exploration is classic scientific research, at least through to the proving Stages.

Jan 1, 1987

The character of alluvial gold deposits presents severe difficulties, and sometimes limitations, on the extent to which metallurgical efficiency can be measured. Very little monitoring of metallurgical performance is practised. An indication of performance is often extracted from the comparison of production to the estimate. This is a dubious practice. The recovery efficiency of conventional practices, viz sluices, tables and jigs, falls off sharply below 0.2 mm. Field evaluation procedures tend to simulate these conventional practices. Thus the presence of fine gold may not be detected, particularly if obscured by clay. There is increasing evidence that fine gold could, in places, be present in sufficient concentrations to be economic. Most gold in paleoplacers is finer than 0.1 mm. There are established practices elsewhere in the mineral industry that may physically recover gold down to 5 microns in size and which could find application for fine alluvial gold.

Jan 1, 1984

By D François-Bongarçon

The link between geostatistics and Theory of Sampling (TOS) is examined again in view of new findings made while trying to compare predicted sampling variances and estimated grades (using geostatistics) on the same material, and this provides an important consistency requirement whenever calculations are made that involve both theories in a comparative way. It also briefly explores the relationship to De Wijs fractal model of mineralisation and eventually provides new support for the use of consistency theory for calibrating TOS variance formulas.CITATION:François-Bongarçon, D, 2017. Theory of Sampling and geostatistics – the ultimate link, in Proceedings Eighth World Conference on Sampling and Blending , pp 391–394 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

EARLY in 1911 the Public Service Board of New South Wales suggested the advisability of inaugurating a School of Mines at Broken Hill, arid made inquiries to determine how such an institution should be conducted. He, the author, believed the Board, as a result of the inquiries, was in favour of the project being worked in conjunction with the Technical College, and hoped to be ready to receive students at the commencement of 1912. That the inauguration has not yet taken place is probably due to the vast amount of consideration and preparation that a new departure of the sort would require. At the present time New South Wales or, to speak more broadly under the same denunciation, Australia is not at all suitably catering for the technical training of young men to provide the increasing demand for officers to work the valuable mines within its territory...

Jan 1, 1912

By Goode RA

It is-assumed that a pipeline system is economically justified as a means of transportation.. The terms "True Life" and "Economic Design Life" are defined. The most usual design alternatives to be considered from both physical and economic -viewpoints are listed and a summary is given of the main factors to be costed in assessing the relative economics of each alternative. A brief statement of the recor mended method af economic. assessment is given and an example is included. The paper aims to present a reasonably accurate, simple and practical method of considering the main economic factors which govern design.

Jan 1, 1962

In September 1980 the N.S.W. Environ- mental Planning and Assessment Act was gazetted. This legislation created a new arena of government involvement in the procedure for obtaining approval to open a new mine, or expand an existing mine in N.S.W. Since 1980 the legislation relating to environmental protection requirements, the procedure for obtaining Development Consent and the nature of relevant government policies have caused considerable confusion on the part of many potential developers. Implementation of the legislation has now become systematic and relatively predictable. However, certain aspects can be improved and require urgent government action.

Jan 1, 1983

Perhaps the only thing certain about an address that purports to look into the future of any human endeavour is that time will prove it :.o be inaccurate. In undertaking the dubious, but oft-times necessary business of prediction, thr, historian will base his/her forecasts on tr-ands of the past, the speculator on current events, and the politician on what he/she would dearly like to see happen. The thoughts expressed in this address seem to have arisen through exercising a combination of all three of those philosophies but, hopefully, with a smat- tering of pragmatism.

Jan 1, 1988

One of primary causes of poor blast performance is the improper relief of explosive energy. Under or over-confined blasts modify the explosiveÆs path of least resistance, which changes where and when the explosive energy is applied resulting in less than optimum blast performance. During the research for this paper the overbreak characteristics of five full-scale blasts were quantified using high speed cinematography and borehole cameras. The effectiveness of various overbreak control methods was also evaluated to guide design refinement. The results of this research along with general recommendations for reducing excessive damage are included with this paper.

Jan 1, 1999

By S E. Thornett, P L. Kitto, R S. Longley

"The Mbalam Iron Ore Project covers mineralisation in two areas of metamorphosed hematitic banded iron formation (itabirite) in the north-west Congo Craton; namely at Mbarga in south-east Cameroon and at Nabeba in north-west Republic of Congo. The site locations are shown in Figures 1 and 2.The Mbalam Project history is an example of a compressed, yet highly successful, exploration timetable. Due to the thick inaccessible equatorial forest location, the first access was by helicopter in February 2007 at the Mbarga Deposit. Drilling commenced four months later in June 2007. A maiden JORC Code compliant æhigh-grade hematiteÆ inferred mineral resource (190 Mt at 60 per cent Fe) was defined in May 2008, followed by a maiden æitabirite hematiteÆ inferred resource in July 2008 (1.2 Bt at 37 per cent Fe). Subsequently, road access to Nabeba was established in January 2010, with a maiden high-grade hematite inferred mineral resource (200 Mt at 63 per cent Fe) identified only five months later in June 2010. A maiden itabirite hematite inferred resource at Nabeba was announced in June 2012 (1.4 Bt at 34 per cent Fe). The success of the exploration programs has been due to two main factors: Establishment of high-quality camps and facilities at Mbarga and later at Nabeba in Republic of Congo. Exploration support included satellite links for site servers and communications, field logging computers, data acquisition software, an on-site sample preparation laboratory, portable hand-held X-ray fluorescence (XRF) and company-owned drill rigs from 2009. An experienced and dynamic technical support group based in Perth to provide database facilities, data evaluation, internal auditing and software support, resulting in expedited resource estimation and economic evaluation with state-of-the-art mining software. In June 2012, Sundance Resources Ltd announced the current mineral resources for the project of 775.4 Mt at 57.2 per cent Fe of high-grade hematite and 4.047 Bt at 36.3 per cent Fe of itabirite hematite. In December 2012, high-grade hematite ore reserves of 436.3 Mt at 62.6 per cent Fe were announced. These world-class resources and reserves have been delineated and evaluated in a very rapid time frame. This would be considered extraordinary in any environment, let alone in the remote equatorial forest of central Africa.CITATION:Longley, R S, Kitto, P L and Thornett, S E, 2013. Exploration history of the Mbalam Iron Ore Project, in Proceedings Iron Ore 2013 , pp 107-116 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 12, 2013

By C R. Ure

To substantially reduce, if not eliminate, carbon dioxide (CO₂) emissions from ironmaking it is necessary to convert from blast furnace (BF) ironmaking using coking coal as the reductant to direct reduction (DR) ironmaking using hydrogen (H₂) and green electricity. Currently, almost all natural gas (NG) based direct reduced iron (DRI) production utilises iron oxide pellets in shaft furnaces, as opposed to fines in fluidised beds. Also, these pellets are ordinarily produced from high-grade magnetite concentrate, rather than hematite and goethite with typically higher gangue contents. The use of high-grade magnetite concentrate is driven by the preference to melt DRI in conventional electric arc furnaces (EAFs), thereby avoiding the basic oxygen furnace (BOF) for making crude steel (CS). However, in replacing BF with DR ironmaking it is not economically feasible to source enough high-grade magnetite to replace the lower grade hematite and goethite currently consumed. That is not to say that hematite and goethite, or even low-grade magnetite, cannot be used in DR ironmaking. However, their higher gangue content, resulting in higher slag production, requires that the EAF producing CS be replaced with a submerged arc furnace (SAF) that will produce pig iron (PI) for the BOF as does the BF. Here, critical issues to be addressed are, what are the technicalities in replacing high-grade magnetite concentrate with hematite and goethite and NG with H₂ in DRI pellet production and melting? This paper summarises certain relevant published information on DRI pellet research, test work and production together with relevant information on Pilbara ores. It attempts to illustrate the inter- relationship of composition and processing conditions on DRI pellet properties. It is intended to serve as a rudimentary guide to understanding the complexities of formulation, testing, evaluation, production and goethite and offer insight into this challenge.

Sep 18, 2023

By G Sartor, A Rich, D Grimsey, R Forzatti, M White

An in-depth process model was developed for the pyrometallurgical, off-gas systems and water balance of the Kalgoorlie Nickel Smelter. This model was used to assess plant capacity with changing concentrate grades, increased throughput and tighter environmental emissions under a range of potential future operating conditions. Comparison of modelled results allowed for flow sheet optimisation across a range of metrics including sustainability, processing capacity and costs. Process modelling software, METSIM® (ver 2020.06 by METSIM International), was used to simulate the flash furnace, integrated electric slag cleaning furnace, Pierce-Smith converters, matte granulation, waste heat boiler, hot gas handling equipment, wet gas cleaning plant and acid plant. The METSIM® model was divided into three separate, yet interconnected models: metals, off-gas and water balancing. This allowed for improved modelling efficiency and traceability while minimising manual error. The METSIM® model was supported by inputs from other specialised software. Chemical thermodynamics software, FactSage™ (ver 8.2 by GTT Technologies), was used to establish relationships for the flash furnace fluxing strategy and determine the operating temperature. Arena® (ver 16.0 by Rockwell Automation), a discrete event modelling software, was used to simulate material movements within the aisle as well as Pierce-Smith converter operation, allowing for integration with upstream and downstream systems. A dynamic data exchange (DDE) was used to connect the results of each software package, interfacing through Excel® (version 4203 by Microsoft). The integration between models provided a streamlined approach to test capacity, bottlenecks, water consumption and emissions under a range of operating conditions, enabling a more robust process. Further downstream modelling techniques were used to assess mechanical equipment. METSIM® outputs provided key parameters for combustion assessments using computational fluid dynamics and finite element analysis for the furnace mechanical design.

Aug 21, 2024

By J M TORLACH

Learning is an iterative process, and we might reasonably expect that after more than a century of mining during an era of sustained technological development, (following a millenium or two of unrelieved hard physical graft), that the more obvious physical hazards could by now be competently managed. It is perhaps a reflection on the perversity of human nature that we have not fully learned our lessons in this exacting environment, and that worse, we have still too often failed to profit by the experience of those lessons. The more obvious underlying factors which impact on this situation are examined briefly, as a prelude to consideration of some outstanding examples of recurrent problems experienced in recent years. Reasons for the continued existence of sub-standard practices are outlined, with a focus on the human element, and finally proposals for appropriate remedial strategies are summarised. This paper therefore seeks to examine and discuss some of our deficiences and to suggest some directions for the way ahead.

Jan 1, 1992