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By Whiten W. J

Data from ball mills of a wide range of sizes are analysed using detailed mathematical models and non-linear least squares fitting techniques. In this way model parameters are obtained describing the behaviour of ball mills over a wide range of mill sizes and operating conditions. These parameters define the flow and breakage of each size fraction of ore in the mill. Flow of coarse particles through the mill is found to depend on the proportion of coarse particles present. The breakage rates of coarse particles are found to decrease markedly with mill diameter for mills over 3 m in diameter.Simulation of grinding circuit throughput at constant productsizing for different mill diameters shows that throughput is proportional to theoretical mill power consumption for mills up to about 3 m in diameter. Thereafter the throughput gradually falls below that indicated by power consumption, the decrease becoming quite significant for large diameter mills. Simple qualitative physical arguments are presented to explain this behaviour. The models developed have applications to ball mill scale up. Work on their further development is continuing.

Jan 1, 1982

By D Pepper

Despite the limited literature regarding the pressure filtration of mine tailings (compared to the large number of papers published each year on paste thickening of tailings) the number of mines dry stacking filtered tailings is approximately equal to the number of mines storing tailings in paste form. Main drivers for filtering tailings are: water recovery, future rehabilitation costs for tailings storage area and permitting requirements. In arid climates, the cost and scarcity of water justify the capital and operating costs associated with pressure filters. Further justification for filtered tailings is the potential for progressive reclamation of the dry stack, which can proceed earlier and faster than the reclamation of a tailings dam.Filtered tailings must be transported to the storage area by trucks or conveyors. For dry stacking, 70 - 80 per cent solids content (by mass) is typically acceptable, however the primary goal is to provide a filter cake that is consolidated and dry enough to prevent bridging and build-up on the materials handling equipment. It has been observed that high average solids contents (~70 per cent) can be achieved while the centre of the filter cakes is still wet and sticky, presenting challenges for the transportation of the solids. Appropriate controls must be in place to ensure consistently easy to handle solids are discharged from the filter.FLSmidth has installed two fine coal tailings dewatering systems in the United States. One of these systems incorporates a Deep Cone Thickener« upstream of the filter press to minimise the amount of water that must be filtered, while the other tailings filter press is fed by a high rate thickener. The operation and performance of these filters is discussed and compared to the lab testing used to size the full-scale equipment.CITATION:Pepper, D, 2012. Operation of filter presses for tailings dewatering, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 241-246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Braham B

The Australian mining industry isstill labouring under the impression. created by the Fitzgerald Report that it does not pay suffic- ient tax. This would appear to be the raison d'etre of the resource rent tax debate. The authors quantitatively compare the cash flows to the mine and government resulting from a large strip coal mine in central Queensland under a number of Australian and international taxation policies. The Liberal government policies are found to be internationally competitive while the Labor 1975 policy is excessively punitive. The present value of the returns to the public from the Liberal 1977 policy vary between three and six times the net present value to the mine, which belies the necessity for the imposition of a super tax. The levelling of a special royalty, excess rail freight, by Queensland could severely re- strict the development of new mines in the Bowen Basin. The impact of excessive freight rates is analysed on a combined strip-deep mine typical of the new projects nearing development in the region. Otherwise economic mines can be made marginal or even sub economic by this tax. Even with moderate rail freights, the mining tax laws of New South Wales are more favourable to the industry than are Queensland's.

Jan 1, 1978

The type of population encountered in the sampling of coal, ores and other products of natural phenomena is one in which the variance within a cluster of elements generally increases steadily as the size of the cluster increases. To enable estimation of variances of stratified random or systematic sampling for such populations one must model the serial correlation function or alternatively, the variogram function. The author has postulated a specific symmetry of the serial correlation function which leads to expressions with rich theoretical and practical implications. These expressions provide a spatial correlation function which explains power law relationships often observed in studies of dispersion variances. They also enable straightforward calculations of sampling variances. The importance of the role of finite population size in the equations leads one to examine previously held concepts of ælargeÆ and æsmallÆ sample populations. The model based on the symmetry postulate is a fractal model with the serial correlation function of a hypothetically infinite population being of the same form as that developed by Mandelbrot for discrete fractional noise. Techniques used in fractal mathematics apply, including box counting and fitting of a dimension function. The paper establishes a framework for the understanding of this fractal theory and demonstrates how to calculate sampling variances from the model variogram using simulated data fitting the model.

Jan 1, 2008

By Baafi EY

Deposits of gold, silver and other precious metals often display a high variability of grade values, usually a very low average metal content and are frequently not easy to sample reliably. The characteristics, together with the volatility of precious metal prices, make evaluations of precious metal deposits extremely difficult to make. Geostatistical estimation techniques can be used to make grade estimates of precious metals and to assess the reliability of these estimates. Two case studies are presented.

Jan 1, 1987

By Morris A. E

The thermodynamically-based pyrometallurgical simulation software STEPSOL (Version 3.0) provides for the modelling of activities using the Interaction Parameter Model, the Regular Solution Model, the Sub-Regular Three Suffix Margules Model, the Sub-Regular Four Suffix Margules Model and various simpler polynomial models. These are briefly reviewed, along with the major sources of data available in the literature, and the implementation of the models in the program.

Jan 1, 1992

By C Ward, U Mueller

Compositional geostatistics is an approach developed to ensure that the constant sum constraint induced by geochemical iron ore analysis is respected in estimation and simulation. Jack-knifing and cross-validation were used within this framework to compare the results from ordinary cokriging of the additive log ratio (alr) variables with those from conventional ordinary cokriging. Two methods were used to back-transform the alr estimates: the crude additive generalised logistic back transformation and numerical integration via Gauss-Hermite quadrature. Previous work on a blasthole data set from a Yilgarn iron ore mine showed promising results, with the Gauss-Hermite quadrature method returning results comparable to ordinary cokriging from the point of view of bias, but superior in that the constant sum constraint imposed by geochemistry of the data was honoured. Other practitioners have noted that the linear interpolation of non-linear log ratio transformations will result in biased results, and that this bias can be masked in a (grade control) setting where the spatial density is high. To test this assertion, the methodology has been extended to successively lower spatial density data sets. The results and applicability to routine iron estimation are discussed.CITATION:Ward, C and Mueller, U, 2013. Compositions, log ratios and bias - from grade control to resource definition, in Proceedings Iron Ore 2013 , pp 313-320 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

ADDRESS BY THE PRESIDENT OF THE INSTITUTE (MR. J. G. SYMONS) IN PRESENTING THE CERTIFICATE TO ROBERT COLVILLE BRADSHAW, O.B.E.Today it is my privilege and pleasure to introduce to you, Robert Colville Bradshaw. O.B.E., the third New Zealander to be honoured with Honorary Membership of The Institute. Sir William Hudson and Mr. C. H. Benney were the others.Mr. Bradshaw has been an Affiliate Member of The Institute since the formation of the New Zealand Branch in 1966. Like his friend Matt Benney. Bob Bradshaw is an accountant by training. Last June he retired as senior partner of the firm of chartered accountants, now known as Wilkinson Wilberfoss, with which he served from January 1929.Mr. Bradshaw grew up in New Zealand attending the Terrace School in Wellington, the New Plymouth Boys' High School where he was a boarder, and completing a Bachelor of Commerce at the university now known as the Victoria University of Wellington. He is an elected Fellow of the New Zealand Society of Accountants and an Associate of the United Kingdom Institute of Cost and Works Accountants.

Jan 1, 1977

By P K. M Mazzoni, D Frantois-Bong

This paper aims to show alternatives to the estimation methods used for finding the parameters in GyÆs well known model for sampling variance in the case of particulate materials. Many experiments designed for gathering data on the sampling variance for specific mineral deposits allow the experimenter to use approximations in the calculation of the parameters of the mathematical model involved, which sometimes can be very useful. However, there are some instances where approximations lead to biased estimates of the parameters, and consequently, lead to errors in the establishment of the sampling protocol and treatment of quality control data. In the present work, an alternative is presented for computing the parameter values based in any experimental set up, without the need for any simplification. The method was derived using the method of least squares and evaluations are made using the usual tools in this kind of methodology: residual analysis and evaluation of the fit by means of a plot of calculated versus experimental variances. With the aid of these tools, one can better evaluate the structure of the experimental errors in such applications, and the adherence to the proposed model. In addition, it is possible to perform hypothesis testing for the equality of different sampling procedures in terms of sampling variance. The full mathematical details are given, together with an algorithm for applying the method, which can be implemented easily using any computer language. An illustration of the method is shown, considering the international work done in ISO/TC 102. This example is a determination of the minimum sample mass to be collected in iron ore shipments, in order to achieve a specified sampling precision.

Jan 1, 2005

This session comprises six papers: One paper is specifically on advances in drilling techniques, a paper presents a classification for water inrush rich with corresponding guidelines for protection, two papers are concerned with mining impacts in integrated catchment management - one from the quality viewpoint and the other from the quality viewpoint, and the final two papers are case studies of mine dewatering - one for an underground mine threatened by a karst limestone aquifer and the other of an open-cut mine threatened by interbedded sand aquifers. The paper entitled, Practical mine dewatering by means of surface drilled wells by Sides is innovative in presenting the case for wells as cost effective and appropriate for a number of purposes including exploration, re-opening old mines, dewatering, grout emplacement and monitoring.

Jan 1, 1988

By R Gaze, J Horton

Block models generated with all linear interpolation algorithms contain inherent smoothing that typically results in an underestimation of grades and overestimation of tonnes in resource estimates. For mineral deposits that are anticipated to be exploited by underground mining methods excessive smoothing may result in materially misleading estimates of Ore Reserves. To account for smoothing in the open pit mining environment recoverable reserve techniques such as indicator kriging and uniform conditioning are employed to provide non-spatially located proportions of the large blocks above the cut-off grade. These models are not suitable for underground mine planning where the actual location of material above cut-off is required to design its extraction. To correct for excessive smoothing it is proposed to modify the ordinary kriged block estimates a posteriori using an affine correction with a local variance adjustment factor. The proposed methodology is demonstrated for a base metal deposit during a feasibility study.

Jan 1, 2009

By Jr

This paper provides a comprehensive review of the requirements of a full due diligence study for a coal property acquisition in both text and table format. From the initial scoping of the assignment, the paper discusses in depth from reserve base validity and mineability; historic performance; plant and equipment; future mine plans; infrastructure; capital spending and operating costs; labour and management; future risk assessment and environmental liabilities; marketing; valuation and finally acquisition synergies. All are important areas to ensure the viability of the acquisition and to identify and minimise the project risks.

Jan 1, 2003

By S Meffre, A E. Fallick, K Zaw, I T. Graham, G Giuliani

Dispersed gem corundum is mined from placers, commonly from basalt fields, as occurs along eastern Australian and Asian continental margins. New laser ablation inductively coupled plasma mass spectrometry analysis (LA-ICP-MS) of Australian corundum allows genetic distinctions among these suites and gives clues to their primary lithospheric sources prior to basaltic delivery. Bimodal corundum suites at Barrington Tops, Cudgegong-Gulgong-Macquarie River and Yarrowitch, New South Wales (NSW), include lower Ga, higher Mg æmetamorphicÆ and higher Ga, lower Mg æmagmaticÆ groups. The Barrington Tops æmetamorphicÆ corundum is more Fe-rich (av 4500 - 7100 ppm) than Cudgegong- Macquarie River equivalents (av Fe 1800 - 2100 ppm). Yarrowitch corundum is relatively low in Fe, Ti and Cr. Along with other eastern Australian data (north-east Tasmania; New England, NSW) and from gem fields elsewhere, the combined trace element and O isotope data, reveal considerable geographic and genetic variations within the corundum suites. A few corundum groups contain noticeable Be, Sn, Ta, Nb, a particular genetic message that also precludes easy distinction of treated corundum in the gem trade. Expanding geochemical, inclusion and geochronological data on gem corundum hold promise for characterising derivative gem corundum on both geographic and genetic features.

Jan 1, 2008

By Kuzugundenli OE, Nagaraj DR

Organic complexing agents have received special attention over the past few decades in the search for reagents for improved flotation separation of minerals, especially non-sulphides. The majority of such reagents that have been proposed over the past few decades have remained largely a laboratory curiosity, except perhaps alkyl hydroxamates, because their selection is seldom based on commercial viability. In this regard, the choice of complexing agents such as oximes may be more realistic because of their widespread use in solvent extraction of copper. Our earlier studies have confirmed that they are also effective as collectors for copper oxide minerals, including chrysocolla which is the most difficult copper mineral to beneficiate. The flotation behaviour of chrysocolla for several structurally-related hydroxyoximes were studied as a function of pH and oxime concentration and the role of structural features examined. The structural changes studied included substitutions in both chelating and non-chelating parts of the molecule. The results indicated that, contrary to expectations, many of the structural changes in the basic molecule, salicylaldoxime, do not have a positive effect on collector efficiency. The reduction in collector efficiency is rationalised on the basis of possible steric factors affecting complexation and packing of the collector species on the mineral surface as well as effects due to changes in electron density brought about by substituents. Introduction of alkyl substituents on the oximic carbon of salicylaldoxime yielded the highest collector efficiency.

Jan 1, 1993

Largely inherited from the past and from strictly internal laboratory use, the certification of reference material using round-robin assaying is often insufficient for the use made today for external assay laboratory control by client parties. Certification often needs to be revisited on the basis of existing round-robin data, especially to derive reproducibility parameters to the end of establishing probabilistic performance gates for operational error detection on a batch per batch basis (ie batch-ærejectionÆ). The most common difficulty arises when only a few certification samples have been analysed in one single batch by each laboratory, so that the round-robin data do not contain the full variability that needs to be quantified. Existing certification data sets from properly submitted round-robin samples were studied using analysis of variance to derive a remedial method, leading to the proposal of default correction factors to restore full variability estimates when no other avenue is available.

Jan 1, 2008

By H El-Shall, R Stana a

An innovative process for the separation of carbonaceous minerals from bulk ores is presented. In this process, the surface of carbonate minerals is reacted with acid used to nucleate CO2 bubbles at the particle solution interface. Entraining the liberated CO2 gas at the surface via coating agent renders the particle more buoyant providing for a selective separation from non-carbonate containing masses. Different surfactants were tested to stabilise the bubbles and float the particles. In this paper, separation of dolomite from apatite using PVA (polyvinyl alcohol) as a coating agent, is discussed. Interestingly, up to 10 mm particle sizes can be floated. Moreover, flotation of a phosphate and dolomite mixture was carried out and MgO content

Jan 1, 2005

Modern minerals projects face serious challenges in earning and maintaining acceptance by their key stakeholders. Factors which underpin effective response to managing these challenges include consideration of public affairs issues from the earliest planning stages, building robust alliances with a range of influential partners, developing a level of transparency in all operations and decision-making and integrating activities towards resolving key strategic issues. Effective community relations is vital and there are a number of elements common to the best approaches. These include senior management support and involvement, appropriate involvement in project decisions and activities by community members and company responsiveness to community expectations. The project's operations manager and executive team must fully commit to developing the capability and processes to meet these challenges. They require a whole of project response and it is not an option to manage them peripherally.

Jan 1, 1997

By Q Zhou, H Nordberg, W Wang-Geissler

Efficiently controlling foam/froth within mineral processing continues to pose a challenge to the mining sector. The foaming characteristics of aqueous solutions for two-phase systems of air/liquid are well-studied with theories and mechanisms proposed to describe and predict foam formation and stability. The types and structures of reagents that either promote or prevent foaming/froth formation and stability are well-defined in these studies and practiced across various applications. Three-phase systems of air/liquid/solid, such as froth from mineral slurries, however, pose a challenge with the presence of a large quantity of relatively fine mineral particles. Theories and mechanisms that rationalise the effects of chemical additives as a defoamer or foaming agent in aqueous can be applied as a general rule, but do not provide the most effective solution for mineral slurry systems. Silicone-based defoamers, particularly their O/W emulsions, have been widely and successfully used at various stages of mineral processing to efficiently control the mineral slurry foaming properties. However, their foaming control ability could be significantly impacted by different processing aids used during the upstream process. In a zinc-rich mineral system, a silicone-based defoamer starts losing the properties necessary to effectively control foaming in the leaching circuit when throughput is increased. In this study, the synergistic defoaming/anti-foaming effects from surfactants and silicone-based defoamers are discussed to effectively control foaming/froth in the zinc leaching circuit, even with lower total defoamer dosage. Improvements during mineral processing can also lead to a cleaner mineral grade by reducing waste.

Aug 24, 2022

By Thatcher R

In areas where undeveloped land represents a scarce resource, an upgraded post mining land use can result in economic benefits to both the mining company and to the community. A study undertaken at Allied Queensland Coalfields Ltd's Aberdare Colliery located between Brisbane and Ipswich during 1986/1987, assessed the costs and benefits of developing the site following mining for grazing, forestry and residential uses. The proposed final land use plan comprised a combination of these uses which can be upgraded to higher valued uses once subsidence monitoring of backfilled opencut areas and dumps indicates that total settlement has reached acceptable levels. The study involved the documentation of existing site environmental parameters and the delineation of site opportunities and constraints. The unpredictable nature of settlement over backfilled opencuts and overburden dumps represents the major constraint to urban development on mined areas.

Jan 1, 1987

By O J. Restrepo Baena, S Nowosad, R Webber-Youngman, N Mojtabai, P Foster, A Binder, S Hazuria, erson, S Raval, L Liu

As the mining industry faces times of change, new challenges arise to ensure raw material supply for the younger and future generations. Different scenarios are currently shaping the way we mine and teach mining engineering. Led by an increasing demand for raw materials, net zero requirements for improving long-term operation performance, technological advancements such as automation and digitalisation, safety improvements, environmental considerations and a need for social acceptance, mining is pursuing to change and adapt to these requirements at a faster pace. Such changing times raise new concerns, one of the most relevant is the lower number of students interested or enrolling in mining engineering and related fields leaving mining engineering as one of the less preferred career options between the younger generations. Nonetheless, it is essential to continue addressing and supplying the skill sets that is suited to contemporary and future of the mining industry. To this end, globally, academia is currently undergoing several initiatives such as curricula updates and adaptation, up skilling, improving teaching practices and techniques, including e-learning techniques, enhancing industry-academia and inter-university collaboration, and much more

Sep 1, 2024