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By G Turner-Saad

An improvement to cut-off grade optimisation theory based on geometallurgy has been completed. The improvement fundamentally consisted of taking into account mineralogical and textural characteristics instead of grades. These characteristics are related to the spatial variability of mineral abundance, association, particle size and liberation properties. Additionally, the improve- ment considered the spatial variability of mineral processing liberation and selectivity properties associated with mineralogy and texture. The enhanced optimisation enables estimation of the economic value of mining operations based on an optimum cut-off policy attributed to liberated and selected ore minerals.The enhanced optimisation was developed as an essential component of a joint cut-and-fill mining and mineral processing methodology based on mixed integer mathematical programming. The formulation considers static and dynamic modifying factors that vary over the projected life of mining. The objective function of the mathematical formulation consists of maximising the realistic expected economic value of concentrates or products of liberated and selected ore minerals, whilst minimises liberated and selected gangue minerals. The optimal solution is obtained when the objective function is subject to geological, mining, processing, marketing, smelting, refining, environmental and financial constraints. The methodology accesses geometallurgical multivariate resource models, which integrate the spatial variability of mineralogical and textural characteristics and mineral processing liberation and selectivity properties.The geometallurgical process concurrently optimises stope geometries, ore reserves, mining sequences, and mining and mineral processing production based on the enhanced cut-off of liberated and selected ore minerals. In addition, the process considers additive and non-additive transfer functions associated to mutually exclusive geometallurgical spatial domains. The transfer functions also take into consideration the blending of mineralogical and textural characteristics with mineral processing liberation and selectivity properties.This contribution presents an example of cut-off grade optimisation via mineralogical and textural characteristic, and liberation and selectivity processing parameter optimisation for a spatially variable orebody.

Sep 5, 2011

By H S. Pescini

A material aim when feeding ore blends into a processing facility is to reduce the variability of the properties of the feed material and to maximise the output, or throughput. At the Mining Geology conference of 2019, we presented a paper on optimal blending of coking coal given geological variability. The paper introduced integer-programming techniques to both maximise value and minimise feed or product variability. We discussed an application where the geological uncertainty is characterised using a normal distribution and exact solutions are readily obtainable using second order conic constraints in the mathematical model. Geological uncertainty is not always normally distributed, many properties will be characterised as log normal or some other skewed distribution. For example, copper can be some form of lognormal and Fe in Iron ore has a left skewed distribution. In this paper, we discuss some distribution free techniques to optimise the blends of plant feed or output given a quantified geological uncertainty. We discuss the sample average approximation method and how to set-up and apply the method to an ore blending problem. Evaluating a case study demonstrates that the explicit use of non-normally distributed geological uncertainty can better optimise feed into an ore processing facility and potentially add significant value. The approach is equally applicable to all mining and processing operations that blend material into a processing facility or directly into a saleable product.

Mar 22, 2022

By S A. Prevec

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Traditional models employed to genetically link associated chromite and platinum-group elements have favoured crustal contamination as the primary process for inducing sulfide and oxide saturation. The association of chromite ores with crustal contamination is well established in the literature. However, in the 1970s (cf Irvine, 1973, 1975), Irvine demonstrated that crustal contamination was in fact problematic as a tool for inducing chromite precipitation in mafic to ultramafic magmas. His results are re-examined here, along with some attempts to reconcile them with the effects of adding Fe to the models. It is concluded that crustal contamination is indeed problematic based on phase relationships alone. However, the role of fluids as a compensating agent is evaluated, which may explain why crustal contamination may indeed facilitate oxide and sulfide precipitation.CITATION:Prevec, S A, 2015. Chromite and platinum-group elements coprecipitation by crustal contamination or magma mixing revisited – genetic and exploration implications, in Proceedings PACRIM 2015 Congress, pp 311–316 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By R Berry, A Escolme

"Predictive geometallurgical models are being developed for the Productora Cu-Au-Mo deposit based on geochemistry to reflect variability in Cu species based on Cu sequential leach data (ie oxide, transitional-oxide, transitional-sulfide, sulfide and non-recoverable Cu).Productora, located in the coastal range of northern Chile, is a magmatic-hydrothermal tourmaline breccia-hosted, structurally controlled Cu-Au-Mo deposit hosted by a thick sequence of Jurassic rhyodacitic volcanic rocks. North and north-west striking fault sets control the distribution of mineralised breccias. Alteration is widespread, complex and pervasive. Hypogene alteration assemblages range in composition from distal magnetite-amphibole, to sodic-calcic, to sodic, to phyllic, to proximal potassic. Low-temperature advanced argillic assemblages are locally juxtaposed next to proximal high-temperature K-feldspar-tourmaline assemblages. The dominant hypogene Cu phase is chalcopyrite.A simple Cu species classification scheme based on sequential leach data and S per cent was devised to account for non-recoverable Cu (ie non-sulfide Cu), which is insoluble in weak acids. Through machine learning, a proxy for this Cu species classification scheme was developed based on: depth, Ca per cent, Cu per cent, Fe per cent, K per cent, Mn ppm, S per cent and Ln(Cu/S) plus logged regolith class, thus allowing classification to be extended to areas of the deposit where no sequential leach data are available. The modelled data has been used to generate deposit-wide 3D models for Cu species classification.The validity of the proxy Cu species classification model is being tested against the results of flotation analysis. Initial results indicate that geochemical proxies can be used to successfully predict Cu species class and provide a high density of classification data.CITATION:Escolme, A, Berry, R and Hunt, J, 2016. Predicting Cu Species Classification Using Geochemistry at the Productora Cu-Au-Mo Deposit, Chile, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 113–118 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

Coal mining in the Illawarra commenced in 1848. By the early twentieth century mining operations were spread over quite a distance along the coast centred on Wollongong. By this time there were already numerous tunnel mines and one shaft mine. Coal was first reported in Illawarra by Lieutenant Flinders on a voyage of exploration, southerly along the coast from Sydney in 1796. Because of the topography, particularly the escarpment and the narrowness of the coastal plain, access from Sydney was not easy by land and the normal access was by sea. It was not until some coastal areas had been developed for agricultural purposes that the mining of the seams on the South Coast commenced for the supp- ly of fuel. The most important mines in the early nineteenth century were Bulli and Osborne Wallsend. In general, coal was won from the tunnel mines and was transported directly, usually by tramway, to the nearest shipping point. Considerable hardship attended the earliest attempts at mining coal in regard to materials for mining and the way of life of the miners in the vicinity of the mines. With the growth of production and the installation of coke ovens at some mines the area, hitherto virgin bush- land, began to take on a more industrialised appearance. The mines were necessarily small,

Jan 1, 1976

Around no subject of technical )uterest have prejudice and wrong-thinking in the past so wrapped a web of obscurity as that of the corrosion of metals.It is a matter which has primarily concerned the engineer, but the paucity of his training in chemistry and electrochemistry has been the stumbling block to a better understanding of its mechanism.Now that the more important conditions controlling corrosion have been scientifically.established, it can be seen that, with the exception of but a few of the minor points, the electrochemical laws enunciated by Faraday, Helmholtz; Nernst, and others, are sufficient to include all the facts of the process.The word corrosion (derived from the Latin rodere-to gnaw) is so often wrongly applied that a definition at this stage would be useful. As now understood, it means the dispersion and waste of the useful solid metal by conversion into a useless compound which mayor may not be retained on or near the metal remaining.Commonly the presence of these compounds is regarded as evidence of corrosion, but the converse is not necessarily true; the lack of visible corrosion products on a clean surface of metal is no criterion of the absence of this change. It may be difficult to prove that the erosion of such a surface has been caused by chemical and not by mechanical effects alone.

Jan 1, 1932

Characterising the weight percentage of each mineral in base metal ores is an integral part of assessing the quality of an ore in terms of its processing properties. The Rietveld method, which uses X-ray diffraction data, has been applied to routinely quantify the minerals in lead/zinc and copper ores from Mount Isa Mines Limited and supergene copper ores from Ernest Henry Mining as well as their related products from the concentrators. The Rietveld method has been tested by comparing Rietveld mineral data with a standard sample with known mineral weight percentages and comparing Rietveld mineral data with mineral data calculated from elemental assays where the element only exists in one mineral such as lead in galena. Where this latter situation does not occur, the Rietveld method has been checked with both elemental and optical microscope data. In all cases, there is a good correspondence between the Rietveld data and the data it was checked against with absolute differences generally in the range of 0.5 to 3 wt per cent. The Rietveld method generally quantifies all minerals occurring over 1 wt per cent in one analysis and is less expensive and more routine compared to traditional methods such as optical microscope point counting. The Rietveld method can be applied to many stages of the mining cycle such as exploration, feasibility studies, mining, minerals processing and for environmental studies.

Jan 1, 1998

By Lysnar R, Horswill M

Since the introduction of the pocket calculator, electronic measuring equipment, lasers and computers, the mine surveyor's approach to his work has changed. Where he once used steel bands he now uses infra-red, visible light or radio waves. The reading and storing of angles is done automatically and he now has to be familiar with the facilities that a computer can offer, instead of plotting and calculating manually. This highly sophisticated equipment is continually being upgraded, modified and fine tuned. This paper will attempt to highlight some of the equipment at present in use by the surveying profession and research currently being conducted by the WA School of Mines. The various options in EDM will be considered including the latest unit capable of measuring distance without the benefit of a reflector, thus enabling the surveyor to co-ordinate points that were previously thought inaccessible. The School is currently working on changes to the GAK1 Gyro Theodolite which may improve results and enable the operator to have more control and confidence in his observations. Areas under consideration are improved lighting, binocular viewing and interfacing the instrument to a stopwatch. In the last few years the computer is being used not only for surface pickups and control but also for underground work. We will highlight the underground options in this area and the software available.

Jan 1, 1987

The subject of government involvement in industry is, to say the least, a touchy one. For many it conjures up thoughts of socialisation or nationalisation. For others it is a desirable objective and is seen as a means of social reform by giving government a greater say in the control and distribution of human, financial and natural resources for the betterment of the community. Whatever your point of view, it is difficult to deny that government involvement exists to lesser or greater degrees in all industries. The mining industry is no exception and the degree of government involvement is probably greater than it is in other industries. I think it is important to remember when talking about government involvement in industry to recognise that there are different types of involvement and that all governments have a right, if they so desire, to become involved in whatever way they choose. The decision of a government to increase its direct or indirect involvement must, of course, be taken in the national interest. Governments, if we are still old fashioned enough to believe in ministerial and electoral responsibility, must make up their own minds about whether their actions are in the national interest and they must be prepared to accept the consequences of that action, good or bad. For instance, they must decide

Jan 1, 1975

By F Pavloudakis

The installation of on-line analysis systems in the open-pit mines of the Public Power Corporation SA (PPC, the state-owned electricity entity of Greece) is considered to be the key-parameter for performing improved quality control and blending/homogenisation of the produced lignite. In order to investigate the accuracy of these systems under the site-specific conditions of the Greek lignite deposits, a research project was carried out. This was necessary since there is lack of experience in using on-line analysers in mines that produce a fuel of such a poor and largely fluctuating quality. After thorough market research, a dual energy gamma ray transmission on-line ash analyser was installed in Kardia mine of Ptolemais û Amynteon Lignite Centre, which is located in West Macedonia, Greece. The initial results obtained after the realisation of a series of dual-comparison trials (ie using two series of reference values that allow three-way comparisons) pointed out several problems that obstacle the achievement of high accuracy on-line measurements. More specifically, the measurements obtained by the analyser were higher than the concentrations determined by the two laboratories when the ash content was lower than 12 per cent (in wet basis). On the contrary, when the ash content was higher than 12 per cent, the measurements of the on-line analyser were lower than the concentrations determined by the laboratories. In other words, the range of the measurements obtained by the analyser was narrower than that corresponding to the lab analyses results. Therefore, the use of this on-line analysis system under the site-specific operating conditions of Kardia mine does not guarantee improved quality control of the lignite fed to the mine-mouth located power plant. Most probable reasons that explain the above-mentioned problems are the following: The frequent and widely ranging fluctuations of the chemical and mineralogical composition of the lignite transported by the conveyor belt, especially as far as its calcium content is concerned. This result from the nature and the origin of the mineral matter co-excavated with the lignite, which varies from calcareous marls to sands and clays rich in aluminium and silica minerals. The fluctuations of the lignite quantity transported by the conveyor belt. The change of the linear concentration of iron contained in the fabric of different belt parts.

Jan 1, 2003

By T A. Carter

In 2010 Agnew Gold Mine (AGM) struggled to produce the required tonnages from its stopes. The longhole rises used to create void in stopes were unreliable and often failed to gain the designed rise height. The number of firings per stope was having an adverse impact on the ground conditions at the stope brows, impeding stope productivity.Through practical experimentation with longhole drill rigs, box hole rigs and development drill rigs as well as trialling new methods in conjunction with reviewing drill hole data, drill hole accuracy was observed to be an issue on-site. Innovative dragging methods such as the reverse drag, combined with a slope instead of a vertical face on the rear of stopes, have improved dragging and a reduction of firings per stope, enabling larger production blasts.The methods trialled and subsequently implemented at AGM have facilitated the mine achieving budgeted targets for six consecutive quarters. This paper documents the use of these methods in a key lode of AGM’s operations to improve drill and blast practices in order to achieve production targets.CITATION:Carter, T A, 2014. Improving production drilling and blasting in the Kim South orebody at Agnew Gold Mine, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 251–258 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By Woodcock JT

This paper deals with some innovations and current proposals for the treatment of gold ores and considers the possibilities of incorporating new developments in new or revised ore treatment flowsheets. The main topics considered are I. typical practice in relation to the size of gold particles, 2. concentration of coarse gold, 3. leaching reagents, 4. in situ leaching, 5. heap leaching, 6. carbon-in-pulp adsorption, and 7. treatment of complex ores (gold in pyrite, gold tellurides, and carbon-containing ores).

Jan 1, 1982

The introduction ofa submerged entry tundish nozzle incorporating a cylindrical internal space for argon distribution to its inner bore slab is described. In co-operation with the refractory supplier, four major phases of nozzle development have been undertaken. Problems as well as successes are outlined.Significant reduction in alumina clogging ofnozzles has been achieved along with a decrease in nozzle consumption, using resin bonded alumina graphite with up to 4 different materials "zoned" to give resistance to thermal shock, gas leakage, and erosion.

Jan 1, 1985

By Colquhoun L

Flooding velocities were measured in a laboratory column (96 mm 4) provided with both bottom and side air entry Packings used were 6 mm glass rings and spheres and -16 +8 mm coke. Results showed that when air was introduced through side nozzles flooding velocities were much higher than those obtained when air was introduced at the bottom of the column. Significance of the results and application to blast furnace flooding is discussed from the viewpoint of assymmetric gas flow.

Jan 1, 1975

By P W. Cleary, G K. Robinson, M D. Sinnott

Discrete element modelling (DEM) is a research tool that involves numerically solving the equations of motion of large numbers of particles. It can be very useful for investigating mechanisms that can lead to bias when extracting samples from material as it is carried on a conveyor belt or as it falls from the end of a conveyor belt. DEM is more realistic than conceptual models and mathematical models; but it is not as realistic as physical experimentation. Its primary advantages over physical experimentation are that it is cheaper and that it allows many factors to be varied while keeping other factors unchanged.This paper reviews our investigations of the performance of sampling systems by using DEM. The sampling systems investigated include falling-stream cutters, cross-belt cutters, Vezins and a device called a ætrue-beltÆ cutter, which is being developed. The purpose of the review is to explain what DEM has contributed to the theory and practice of sampling, and to indicate what it is likely to be able to contribute in the future.CITATION:Robinson, G K, Cleary, P W and Sinnott, M D, 2012. How discrete element modelling is influencing the theory and practice of sampling, in Proceedings Sampling 2012 , pp 15-20 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

It has become increasingly clear in recent years that human kind has developed the capacity to alter the environment of the Earth on a global scale. The changes are often subtle. This is particularly true in the case of stratospheric ozone. Ozone is produced primarily in the stratosphere, at altitudes in excess of 20 km, initially through the action of ultraviolet sunlight dissociating molecular oxygen. According to theory as it existed up to a few years ago, ozone is removed mainly by reaction with atomic oxygen. In the unperturbed environment, this reaction proceeds both directly, and by paths catalyzed by trace quantities of nitrogen radicals. Molina and Rowland [Nature, 249, 810, 1974] pointed out that decomposition of industrial chloroflurocarbons could in-troduce an additional source of radicals to the strato-sphere. Chlorine radicals are even more efficient than nitrogen in catalyzing recombination of oxygen atoms with ozone; models suggested that we might expect reductions in the vertical column density of ozone of as much as a few per cent over the next several decades. A reduction in ozone of x¦/a, by increasing the flux of ultraviolet sunlight reaching the surface, was predicted to result in an increase of about 2x% in the number of cases of skin cancer, with other less well defined impacts on the non-human environment for life.

Jan 1, 1990

In the human body, the balance between heat production and heat loss is continuously being disturbed, either by changes in metabolic rate (work being the most influential) or by changes in the external environment (heat stress), which alters heat loss. These changes in body temperature can adversely affect the function of body systems and organs. As a result, heat production or heat loss processes are triggered in order to restore normal body temperature (36 - 37¦C). If the heat generating systems of the body are excessive or the environment hostile then the capacity of the body to maintain thermal homeostasis is exceeded and can lead to a serious threat to health, or even death. This health deficit can severely affect an individualÆs capacity to work optimally; the end result is both poor productivity and health. Strategies to minimise or eliminate this effort will benefit both the health of workers and the productivity of companies. The principal strategies to reduce the effects of the environment on workers are: engineering interventions: to improve environmental conditions and reduce heat stress; and a comprehensive working in heat protocol: with provisions to identify risk situations and procedures to be adopted in relation to these. The above points will be discussed in detail with practical and simple strategies proposed to combat the deleterious effects of heat in mining.

Jan 1, 2005

 Increasing concern about the impact of alluvial mining discharges on the water quality of some West Coast rivers lead to a joint West Coast Gold Miners Associate, Trade and Industry funded study by Water Technology (NZ) Ltd. The objective of the study was to assess the treatability of West Coast alluvial gold mining discharges and to develop simple treatment systems which could be effectively adapted to a variety of sites in the region.   The approach was to apply standard water treatment techniques to field situations using low cost technology. Initially the various types of alluvial gold mining operations were identified then after preliminary site investigations and laboratory studies were carried out, site pilot plants were set up. The results of the trials particularly those using chemical aids were encouraging and it was found that chemical aid performance was largely dependent on the degree of mixing at and downstream of the chemical addition point. Design alterations to settling pond configurations in conjunction with optimised chemical addition yielded dramatic results in the form of reduced effluent turbidities.   A generalised approach to effluent treatment was developed and some of the specific 'mix and match' requirements were identified for different types of sites. The general conclusion is that improved physical treatment combined with good plant management and operation and (where necessary) chemical treatment, will produce water of acceptable discharge quality.

Jan 1, 1989

At the beginning of this year it was my pleasure and responsibility to take over the Presidency of our Institute from Mr A. A. Parish who, as did his predecessors, filled the office with distinction. It is a great privilege to address you as President and it is an occasion for my wife and family, and I am most grateful for your inviting them to the buffet dinner. Our Secretary (Miss Jacka), who processes all Presidents, has told me that there are neither questions nor discussions on Presidential Addresses, and that being so, I felt free to select a controversial topic. The address I have prepared is not strictly true to label; because I intend to include also the effect on agricultural production in Australia if Britain joins the European Economic Community (i.e. the Common Market).Three points of view are1. the European, which is one of equanimity deriving from the initial brilliant success of their scheme,2. the British, which is one of anxiety not to miss the bus, coupled with a commendable wish not to inimically affect existing Commonwealth arrangements,and3. the Australian, which is one of alarm.In England all are drawing their own conclusions on the subject and views range from the extreme desirability, to the extreme undesirability, of the United Kingdom joining.No one in Britain wants Australia, or New Zealand, to...

Jan 1, 1962

By Smit J. G

Following an increase in the number of methane ignitions in South African coal mines a new ventilation system was developed. The "Hydravert" system conceived in late 1979 for use in low seam coal mines, where the bord and pillar method of working is used, has been extensively developed to include applications for mining seams up to 4.5 metres high. A brief history of the development is supplied including some of the pitfalls encountered in the hydraulic equipment design and selection.

Jan 1, 1988