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Recognition is the most important aspect in the use of breccias as an exploration tool. Ore-hosting breccias occur in a wide variety of environ-ments, shapes, compositions and characteristics, but generally present favorable loci for the deposition of ore mineralization in epithermal, porphyry copper-gold-molybdenum, massive sulfide, carbonate-hosted, sedimentary lead-zinc deposits and others.

Jan 1, 1990

The mechanisms of fragmentation in homogeneous materials and structured rock mass are reviewed. A method previously used to predict vibration damage to the remaining rock is extended and shown to be valid for the prediction of fragmentation in the rock mass removed by blasting. The effectiveness of different explosives in different types of rock blasting is discussed.

Jan 1, 1990

Minerals processing needs a step change in energy efficiency. While the search for new technology breakthroughs is important, huge gains are still available by better using existing research outcomes. This potential remains untapped due to a combination of organisational 'silos', inappropriate performance measurement, and poor science in some areas. It is time to see the elephant in the mill.

Sep 13, 2010

By K J. Thompson

This paper describes the work which has been undertaken at the Ohai coalfields in Southland to restore overburden heaps during past opencast mining operations, and procedures which have been adopted to ensure that restoration is achieved concurrent with present opencast mining activities. The system implemented for the treatment of wastewater from opencast mining operati6ns is also described.

Jan 1, 1981

By N Murphy and, S Santomartino, M Cramer

Acid rock drainage (ARD) can have detrimental effects on mining infrastructure, water reuse options and environmental discharge. As a result, some form of short- or long-term treatment is required at many mine sites. Successful treatment depends on a number of factors including the selection of an appropriate treatment technology and its correct implementation. A variety of passive and active technologies are available for dealing with ARD. Passive treatment solutions do not require continuous chemical inputs but take advantage of naturally occurring chemical and biological processes. They are often low cost, site specific approaches and are predominantly used in post-closure situations. Passive systems are well suited to drainage with low acid loads and low soluble aluminium concentrations, and are more effective with highly reduced (ie low oxygen) water. While they are often regarded as permanent fixes, most require some form of ongoing maintenance and all have an engineered life expectancy (ie finite carbonate and organic matter budgets). Passive treatments include, oxic limestone drains, anoxic limestone drains, limestone diversion wells, various reducing and alkalinity producing systems, pyrolusite limestone beds, aerobic and anaerobic wetlands, permeable reactive barriers (organic ¦ carbonate and zero valent iron), slag leach beds, and gas redox and displacement systems (GaRDS). Active treatment solutions require a continuous or semi-continuous activity (eg reagent dosing) to correct water quality issues. They can be engineered to treat virtually any type of drainage or site specific ARD issue, and have no set acid load or redox limitations. Tasks handled by active treatment systems are almost invariably larger and more costly than for passive systems. Active treatment approaches include; pH control, adsorption/absorption, ion-exchange, electrochemical concentration, biological mediation/redox control, flocculation/filtration and crystallisation. A range of generally available and proprietary technologies has been developed around these approaches. Active treatment involving pH correction with alkaline amendments is the most common and cost-effective form of ARD treatment. A variety of fixed plant and portable treatment systems are available. Calcium-based reagents, including quicklime (CaO), hydrated lime (Ca(OH)2) and limestone (CaCO3) remain the reagents of choice for the majority of active ARD treatment worldwide. This is principally due to their widespread availability, non-proprietary nature, and variety of proven dispensing technologies and cost-effectiveness. Limestone, in particular, is a very low cost reagent. However, due to æefficiency of useÆ problems with limestone in passive treatment systems, combined with its very low cost, there has been a recent emphasis on developing active treatment systems that use limestone efficiently. As the requirement for treatment increases, there is a growing emphasis on treatment sludge management and sludge stability. The final choice of a suitable treatment technology is dependent upon water chemistry (eg pH, type of metal contamination, acidity), flow rates, acid load, local natural resources (neutralising materials, topography), climate, site logistics, environmental risk and economics. The benefits and limitations of both passive and active treatment technologies are summarised.

Jan 1, 2003

By D K. Miller, L W. Armstrong

In April 2006, Orica Quarry Services undertook an investigation to determine the likely vibration and frequency response of three water storage tanks to quarry blasting, immediately adjacent to the tanks. Of the three tanks that were studied, two are relatively tall with a æwineglassÆ shape; one is constructed of steel (4 ML storage capacity) while the other is constructed of concrete (2 ML storage capacity). The third is a ground-embedded concrete tank that is relatively squat and broad in shape (38 ML storage capacity). A vibration limit of 25 mm/s and an acceleration limit of 0.16 g were imposed on the tanks. However, this report shows that this acceleration limit, whilst having relevance to low frequency earthquake motions, is quite inappropriate for the high frequency blast vibrations that are typical in a quarry blasting environment. The investigation involved firing 11 single blastholes of known charge weights and distances from the tanks, and measuring the tank vibration response using blast monitors placed on and around each tank. Analysis of the data collected from the cement tanks showed resonant responses over a broad range of frequencies, with dominant and lesser responses in vertical and lateral motion recorded at 9.8 Hz, 12 Hz, 16.8 Hz, 17 Hz, 31.3 Hz and 38.1 Hz. Unfortunately, most of the data collected on the steel tank was corrupted by noise due to electrical sources and/or mechanical sources such as the water agitator inside the tank. Advanced Monte Carlo vibration models were then constructed using the single blasthole information. Knowing the resonant frequencies enabled the modelling of electronic delay sequences for the reduction of resonant vibrations. Ultimately programmable and accurate electronic delay detonators were deemed essential to allow blasting in relatively close proximity to the tanks while avoiding resonant frequencies. Three blast designs were modelled, ranging in maximum instantaneous charge (MIC) from 4 kg to 22 kg, and 60 holes to 160 holes. The modelling showed that two of the designs (using small charge weights) could be used no closer than 71 m from the storage tanks. This is based on a 90 per cent confidence level of achieving vibration levels within the 0.16 g acceleration limit, even though the velocity levels predicted to be generated at this distance were significantly less than the 25 mm/s limit. The third design incorporated larger charge weights and could be used for blasting at distances no closer than 220 m from the tanks. The present work, conducted in an operating quarry, demonstrates the usefulness of Monte Carlo waveform superposition techniques for the control and reduction of ground vibration (either velocity or acceleration) under restrictive environmental constraints. However, a discussion is also presented to demonstrate that it is somewhat restrictive to impose an acceleration limit based on the motion produced by low frequency earthquakes rather than the motion produced by high frequency blast vibrations.

Jan 1, 2007

By J Penman, N Turner, H Liu

This paper aims to present a snapshot of the risk profile for tailings storage facilities within Western Australia by comparing the spatial distribution of known facilities against common geohazards such as cyclonic activity, climate, and peak ground accelerations from earthquakes. The analysis also includes an assessment of proximity to populations at risk including towns and sensitive receptors including significant river systems and wetlands.

Jul 1, 2021

Once and for all, the debate on the exponent in Gy's formula is pushed to its limit. It is explained why an exponent of 2.5, obtained when using a square root of nominal size d to adapt the value of a calculated liberation factor to a different comminution size, will rarely be encountered in practice, if no arbitrary decisions are made.

Mar 1, 2010

By J Bohm, B Csoke, I Tarjan

In process technology, especially in coal preparation, it is often necessary to have a continuous knowledge of the average density of granular material in order to achieve both quality control and process control. The paper presents a new method and means supported by laboratory measurements for the rapid, practically continuous, determination of the average density of continuously supplied granular material through frequent sampling.

Jan 1, 1993

By Mining Geophysics

Modern geostatistics has eliminated much of the guess-work in ore reserve estimation, and can calculate levels of confidence for the reserve estimate. Geological modelling software has brought about a revolution in the communication of complex geo-variables to mining engineers, metallurgists, surveyors and managers. Mine planning and scheduling can now avail itself of a veritable toolbox of enabling technologies.

Jan 1, 1994

By A H. Bagherieh, S Mesroghli, H Jorjani, S Chehreh Chelgani

The rare earth elements (REEs) assay and recovery in leaching processes is being determined using expensive analytical methods, ICP-AES, and ICP-MS. This paper presents a neural network model to predict the effects of operational variables on the lanthanum, cerium, yttrium, neodymium recovery in the leaching of apatite concentrate. The effects of leaching times: ten to 40 min, pulp densities: 30 to 50 per cent, acid concentrations: 20 to 60 per cent and agitation rates: 100 to 200 rpm were investigated and optimised on REEs recovery in laboratory at a leaching temperature of 60¦C. The obtained data, on the laboratory optimisation process were used for training and testing of a neural network. A feed-forward artificial neural network with 4-5-5-1 arrangement, was capable of estimating the REEs leaching recovery. Neural network predicted values were in good agreement with the experimental results. The correlations of R = 1 in training stages, and R =  0.971, 0.952, 0.985 and 0.98 in testing stages were results for Ce, Nd, La and Y recovery predictions respectively and that theses values are considerably acceptable. It was shown that the proposed neural network model accurately reproduces all the effects of operation variables, and can be used in the simulation of a REEs leaching plant.

Jan 1, 2008

By A Bennett, A Peck

BHP has recently constructed a Hot Briquetted Iron Plant at Port Hedland in the Pilbara region of Western Australia. Supply of iron ore fines to the plant is by conveyor from the companyÆs existing Nelson Point stockyards. The conveyor passes under Port Hedland harbour in a concrete segmentally lined tunnel, approximately 1030 m long and with a 5.1 m external diameter. The tunnel was constructed by a Tunnel Boring Machine (TBM) which both excavated the ground and erected the tunnel lining. The tunnel was bored between cut and cover in situ concrete portal structures, the TBM being launched from the Finucane Island side towards Port Hedland town. The alignment required lengthy gradients of 1:6 on either side of the harbourÆs dredged channel, under which the tunnel is bored with a minimum clearance of 8 m.The tunnel is fitted-out with:1800 mm belt conveyor capable of 10 000 tph;walkway along which a specially designed inspection/ maintenance vehicle can run; andtunnel services including power, light, fire detection and suppression communications, water mains for wash down and sumps and pumps for drainage.This paper gives a general overview of the design and construct contract, important aspects of the design and the construction process itself.

Jan 1, 1999

By H Benzer, N A. Aydogan

It is well known that the high pressure grinding rolls (HPGR) can only be operated efficiently under choke feeding conditions in which a material bed is built up between the rollers to ensure interparticle breakage. By increasing the fines amount in the material bed up to a specific level with the recycling load, a uniform material bed is created and higher pressure gradient along the roller width is obtained which results in compact flakes including more fines. Extensive test work has been carried out with an industrial HPGR unit grinding cement clinker in a cement plant in Turkey. During the test work the recycling load of the circuit was changed to achieve different ratios to the fresh feed rate in order to identify the effect of the recycling load on the circuit performance. Six different tests were performed with the circuit at steady state. For each test, samples were collected from HPGR fresh feed and discharge, and total feed, then the particle size distributions of the samples were determined and mass balances around the circuit were calculated. The conclusion was that the reduction ratio of the HPGR increased with increase in recycling load. The flake densities showed the same trend with more compacted flakes being produced for higher recycling loads.

Jan 1, 2009

By M Bond, R R. Hargreaves, G W. Booth

There are numerous causes of speculative mineral resource and reserve inflation. Traditionally, these are linked to issues of data accuracy or misinterpretation, the use of overly optimistic estimation parameters or assumptions, an absence of independent expert verification, or the simple pressure to increase company value, covert or otherwise. Owing to its subjective nature, classification of resources and reserves remains an opaque process. Of necessity, Competent Persons rely on personal heuristic interpretations, ideally underpinned by appropriate estimation and classification experience across commodity and deposit types. Whereas independent verification of individual resource and reserve statements remains impractical, publicly available data can be interrogated for potential category inflation, particularly when viewed with exploration expenditure statistics included in annual company reports. Abrupt changes in category tonnages and market capitalisation without concomitant expenditure can aid in outlier detection. Consequently, a comparison of common exploration and resource reporting parameters offers a basis for risk assessing classification robustness, over time. In this introductory study, an analysis of globally listed companies was undertaken over a multi-year period, examining base and precious metal projects in both preproduction and operational asset classes. From these, a series of exploratory decision tree trigger points were generated against which target companies were anonymously identified and risk-ranked.

May 24, 2023

Two years ago I was sitting in a big lecture theatre at the School of Mines in Kalgoorlie at the annual New LeadersÆ Conference listening to a guy tell us all how much he loved his job, travelling the country ælegallyÆ blowing stuff up à and getting paid to do it. I would have paid to see and do the things he spoke of à now IÆm that guy. From finishing a mining engineering degree at the University of Ballarat, through the job hunt, to firing environmental blasts in Tassie and designing and implementing construction blasts in the middle of the Gold Coast. My name is Rohan Stevens and IÆm a blast-o-holic. While the æjob huntÆ we all embark on toward the end of our degrees is a stressful time, itÆs also very exciting in the current climate. There are a number of things I have learnt through both my hunt for the job that best suited me and working for the worldÆs largest explosives manufacturer. If at least you donÆt benefit from my learnings IÆm certain you will enjoy hearing about (and viewing) some of the work I have had the opportunity to be involved with over the last 18 months with Orica Mining Services.

Jan 1, 2008

By S Hapugoda, Y Tang, L Lu

The steel industry is one of the global leading CO2 emitters, accounting for approximately 7 per cent of global anthropogenic CO2 emissions. In 2022, the world produced 1878.5 Mt of crude steel. About 70.8 per cent of the world’s crude steel was produced by integrated steel mills through the blast furnace and basic oxygen furnace (BF-BOF) process, while the remainder was produced largely by mini mills using electrical arc furnaces (EAF). Compared with gas-based DRI and scrap-based EAF processes, the direct CO2 emissions from the BF-BOF process and the coal based DRI and EAF process are significantly more, as both the processes rely heavily on fossil fuels, such as coke and pulverised coal, to provide energy and reduce iron oxides. Hydrogen is very reactive and reduces iron oxides to metallic iron without generating CO2. Therefore, substitution of hydrogen for fossil fuels in these processes presents a good opportunity to significantly decarbonise the steel industry. This paper will first discuss the thermodynamic and kinetic characteristics of hydrogen and carbothermic reductions of iron oxides and then examine the behaviours of different ore types present in Australia iron ores during hydrogen reduction.

Sep 18, 2023

By B Murphy

Seeking to reduce the likelihood of uncontrolled personnel entry into the operating footprint of a dragline, Coronado Global Resources initiated a review of proximity detection systems currently available and equipment interactions in and around dragline operational areas. At the time of the assessment, there were no established personnel proximity detection systems in compliance with functional safety standards for large machinery in Australia. Our primary objective was to guarantee a functionally safe outcome, particularly by implementing a performance-level-rated system in accordance with AS4024 (Safety of Machinery series of Australian Standards). Applying appropriate detection technologies, the goal was to reduce the residual operating risk for machine-to-machine and machine-to-personnel interactions. A comprehensive analysis of available or in-development technologies was conducted, and a layered approach (demonstrated in Figure 1) was adopted to achieve the desired risk reduction by segregating the sensing zones into distinct areas using diverse and disparate technologies consisting of radar (short); light detection and ranging (LiDAR) (medium); and optical (long). To address the potential limitations of each technology, overlapping layered sensing zones were designed. With LIDAR and optical using two distinct artificial intelligence (AI) systems to classify detections, these were specifically trained to handle the unique environments of a mining operation.

Sep 1, 2024

By P J. Hawke, M F. Flis

The Hamersley Basin of Western Australia holds significant tonnages of detrital iron deposits. Formed by a cyclic weathering and eroding sequence of nominally barren banded iron formation, they may form rich proximal accumulations of iron cemented gravels distal from any obvious hard-rock iron mineralisation. While generally small, they nonetheless represent excellent economic targets as they are near surface and easy to mine. The relatively high density of iron detritals, when compared with their sedimentary hosts, makes the gravity method the primary method of exploring for these blind deposits. Identification of possible trap sites is used as a precursor to gravity surveying, with magnetics used as an ancillary method prior to drilling. Application of the gravity method in this terrain is not straightforward. Detrital trap sites are best developed next to the spectacular cliffs that form the range fronts to the Hamersley Ranges. Precise terrain corrections and use of first vertical derivatives are routinely applied to gravity data in an effort to map every possible gravity high that may reflect the presence of a detrital accumulation. Extensions to Hamersley Iron Pty LimitedÆs BS2D deposit were discovered by the routine application of gravity. This methodology has been used to create a model by which exploration for detrital deposits continue to the present day.

Jan 1, 2002

Mond gas-producer tar, and, in fact, all tars obtained from the retorting of coal where steam and air are admitted to the retort, are of entirely different chemical composition to the ordinary coal tar made in the gas or coke works. These tars contain none of, the aromatic hydrocarbons - benzene, toluene, naphthalene, and anthracene, sought after by the ordinary coal-tar refiner.The distillation of Mond tar shows it to consist of phenols of high molecular weight, unsaturated hydrocarbons of high gravity and low viscosity, paraffin wax, and resinous substances of whose composition little is known.The physical properties of Mond producer tar are also peculiar. It has a "short," granular texture when cold, which might be likened to candied honey. It "dries" (hardens) when exposed in thin layers to the air, and, for a coal tar, it cannot be considered sticky. This latterò property, combined with the short texture, prevents its being used successfully for road-making or macadamizing.The drying properties and the paraffin wax contained in: this tar cause it to hold up large percentages of water, probably in the form of emulsion. When containing as much as 10% to 15% moisture it appears to be quite dry.

Jan 1, 1918

By J H. Park, M J. Lee

Because the environmental problems are occurred by greenhouse gases such as CO2, the industries have tried to increase electric motor efficiency to reduce CO2 emissions. A core material of electric motor is high-silicon electrical steel. The ferrosilicon (FeSi) alloy, a raw material for the production of electrical steel, affects the electric properties of silicon steel. The main impurities such as Ca, Al and Ti make inclusions or precipitates that causes core loss. The slag treatment has been widely used to remove impurity elements. Thermodynamic principles for the refining of several impurities, specifically Ca and Al, have been investigated, whereas thermodynamic behaviour of Ti has not been fully understood yet. Therefore, in the present study, the titanium distribution ratio () between ferrosilicon and CaO-SiO2-Al2O3 slag system at 1773 K was investigated. The results show that is influenced by both the basicity and stability of titanium ion in the slag. Specifically, exhibits a minimum value at about C/S=0.7 indicating a shift in the titanate structure unit from [TiO5]-square pyramid to [TiO4]-tetrahedron because of lack of Ca2+ ions in a C/S<0.8 region, contributing to an increase in titanate capacity and .

Jun 19, 2024