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By R Paterson, A Christensen

The routine use of gravity gradiometry for the detection of orebodies with no outcrop is now being undertaken. The commodities and orebody styles range from banded iron ore formations to volcanogenic massive sulfide (VMS) style polymetallic deposits. This recent innovation of flying gravity gradiometry was pioneered by BHP Billiton and Lockheed Martin with the Falcon technology (Lee, 2001), and now two additional systems, also using Lockheed Martin instruments, are deployed. In South Africa, magnetic gradiometry is being developed and deployed with the same objectives in mind. In this case, a system from Institute of Photonic Technology (IPHT) is being used. The detectable wavelengths from such systems have decreased to less than 200 m in the last year, and it is expected in 2011 that wavelengths to less than 100 m, with anomaly signal strengths of less than 2 Eotvos for gravity gradiometry will be viable. The key to these advances lies in the improvements of processing software and geological modelling. In particular, methods using all the tensor components are starting to be routinely deployed to filter, level and grid the observed signal. These methods do, however, require full insight and understanding of the reference coordinate systems used by the various instrument designers and survey operators. The digital terrain models need also to be observed to an accuracy of better than 20 m cell sizes, using such techniques as Lidar. Then the terrain effects can be modelled. The topographic surface represents the largest and most proximal density contrast encountered in an airborne survey. Hence terrain effects can have significant impact on airborne gravity gradiometry data. A decorrelation of the terrain effect with the observed signal requires a method of best fitting with a regional surface density. A novel technique has been developed for this purpose. This technique uses a tensor algebra to estimate a density between 1 - 4 g/cc that explains the average observed signal. Armed with this result, the anomalous buried bodies can be revealed by subtraction.

Sep 26, 2011

A mineral exploration manager's prime function is to provide a frame- work within which new mine production can be achieved. As part of this framework, the manager should know his employerb future requirements, and should direct exploration towards those particular mineral commodities which indicate satisfactory growth in consumption and price. Selection of these commodities can be assisted by studies of world reserves, and long term trends in price and consumption. Exploration planning is most efficient with an assured and reasonably uniform supply of funds.

Jan 1, 1980

By G Gibson, B Bessen

In coal preparation, large dense medium cyclones (DMC) at low pressure heads (typically 9D where D = cyclone diameter) are the norm. This contrasts with high density mineral applications where, largely for historical reasons, smaller cyclones at high heads are the standard. There are advantages in preferring large diameter cyclones at low heads, assuming that metallurgical performance does not suffer significantly. These include simpler plant layouts, easier maintenance, smaller spares inventories, reduced wear, reduced medium pumping demands, smaller buildings and overall lower capital and operating costs. In 2008, therefore, Xstrata Zinc decided to trial a single DSM-design 800 mm cyclone in one of its four DMC lines at Mt Isa, replacing the four 400 mm cyclones previously installed. Circumstances allowed a low head of 9.5 D to be trialled, compared with the existing 400 mm head of 21.5 D. This paper describes the trial, including tests using painted ore particles as tracers, estimates of yield and metal recovery, and wear monitoring. The larger unit performed well. There was no evidence that metallurgical performance in terms of metal recovery and waste reject rate suffered, and there was some evidence that it may have improved. Cyclone life increased, and preliminary data suggest that the replacement cost of the 800 mm cyclones is less than half that of the 400 mm units, and this is expected to improve. The plant layout and operability have also improved significantly. Xstrata has therefore decided to convert the whole plant to four low head 800 mm units, replacing the original 16 high head 400 mm units. The paper includes an explanation of the effect of static head on DMC separating force. It also reviews earlier research on diamond applications, and applies a general DMC process model to the Xstrata case, both of which confirm that large, low head cyclones are appropriate in mineral applications, contrary to conventional practice. Such units could significantly reduce both the capital and operating costs of DMC plants in mineral applications.

Jan 1, 2009

The discovery of bauxite in 1955 at Weipa on the NW coast of Queensland's Cape York Pen- insula enabled Australia to join the Caribbean and West Africa as one of the major world sources of bauxite. Weipa, today, is the largest bauxite mining operation in the world and holds a significant position on the world bauxite scene as the operation 1. supplies 15 per cent of the Western World's metallurgical grade bauxite requirements, Z. produces 50 per cent of the world's demand for abrasive grade calcined bauxite, and 3. is the world's largest bauxite shipp ing port.

Jan 1, 1978

By Arit I, Adisoma G

General Limit Equilibrium Method (GLE) and Janbu's Generalised Procedure of Slices (GPS) are two limit equilibrium methods in slope stability analysis which satisfy all equilibrium conditions. Numerical difficulties associated with these metho

Jan 1, 1998

Copper grades of diamond drill hole and development samples are determined in the core shed logging area at Mount Isa Mine using a Bulk Mineral Analyser. All geological and grade data on the copper orebodies is collected and stored on computer file.The raw data can be manipulated interactively using a computer terminal or by input of forms to produce output as computer plots or printouts. Grade distribution of copper or cobalt is obtained by the geologist using a computer kriging package followed by grade contouring. Computer plotted cross-sections and plans of individual stopes or several stopes can be produced showing geological structures, kriged grades at points and as grade contours.

Jan 1, 1985

The Hail Creek coking coal deposits are situated in Central Queensland, inland from the port of Mackay. A joint venture of Australian and Japanese companies has been formed to examine the feasibility of developing these deposits for sale on the overseas markets. The project envisaged involves large scale mining operations and on site benefic- iation to wash the coal to marketable quality. Infrastructure items include a 140 kilometre railway to the coast, a port facility, and at Ilail Creek, power and water supplies, roads and communications, and accommodation for a substantial workforce. The need for town development and the responsibility for the development are established. The town planning implications of coal production at the rate of five million long tons of washed coal per annum from open cut and underground mines are considered. A procedure for estimating the size of the town is expounded and the town size is determined. The factors influencing site selection are explained and a site is suggested. A method of designing the town is described and comments are made on developmental aspects. Spaciousness and preservation featuring the natural environment will be the theme of the town development.

Jan 1, 1973

The Operation of the LAROX PF-50 Pressure Filter at 'Ellatzite-Med' Flotation Plant, Bulgaria The implementation of Larox pressure belt filter, type Larox PF-50 provided within 6˜8% moisture content of the produced copper concentrate, which allowed good market realisation. The start-up of the pressure filter in 2009 reduced the electricity costs several times and had a positive impact on the technological regime of flotation. This article reveals the investigation results from the operation of the pressure filter according to different situations (density of the pulp, time for filtration, pressure of the material, pressure of the drying air, time for drying with air and other factors). The investment made in the pressure filter application is a guarantee for the successful operation of 'Ellatzite' flotation plant, Bulgaria in the coming years.

Sep 13, 2010

By M Ahler

Future developments in the mining sector will be driven by the need to increase safety, ecological sustainability and efficiency. Autonomous systems represent a huge step towards achieving these goals. This paper describes the basic infrastructure of an autonomous system – essentially a network of distributed sensors. Although the sensors are distributed, the overarching communication network with its related middleware offers a transparent and uniform layer. This middleware acts as an abstraction layer which priorities information and provides information to other platforms on request. This permits higher-level autonomous functionality to utilise all information available in the system regardless of where data has been generated or via which physical communication link it has been processed.The Personnel Proximity Detection (PDD) system is described in detail as an example, with details not only of the system itself, but also of the essential full integration and how the abstraction layer allows this technology to be plugged in at any location of the network. The paper ends with a summary of the content and a conclusion.

Nov 22, 2011

By L M. Zhang, T H. Xu, J Zhao

Blasting is one of the most commonly used strategies for excavation in civil and mining engineering. Yet blasting can also bring along such undesirable effects as ground vibrations and soil disturbance. Numerical analysis is a powerful tool for estimating the effects of blasting and improving blasting design. In this research, a constitutive model for sand is proposed for the numerical analysis of blast-induced ground motions and wave propagation in soil mass. In the model, three model surfaces, ie the critical surface, the dilatancy surface and the bounding surface, are defined following the bounding surface hypoplasticity framework. The strain rate is included explicitly into the model formulations so that the proposed model is valid under high strain rate loadings caused by blast-induced vibrations. The performance of the proposed model is validated by the simulation of drained triaxial compression tests conducted on a crushed coral sand under different strain rates.CITATION:Xu, T H, Zhang, L M and Zhao, J, 2014. A bounding surface model for sand subjected to blast-induced vibrations, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 201–206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By Nekitel S, Arumba J, Kopi G, Findlay RH

The Kainantu area lies within the composite Scrapland terrane which is composed of Mesozoic metamorphic and intrusive units, overlain by Cenozoic marine sediments, volcanic and intrus-ive units and Quaternary fluvial sedi-ments.Four deformations (Dl, D2, D3, D4) are recognised within the Mesozoic sequences, which consist of greenschist to amphibolite facies schist derived from felsic to intermediate pyroclastic rocks and pelitic sediments. The second, third and fourth fold events are present in the Cenozoic sequence, and these rocks are broken by thrusts related to northwest trending D3 folds. South-dipping, possibly lystric, normal faults are recognised and may be related to uplift and exposure of the metamorphic rocks as core complexes.Known mineralisation in the area consists of gold and copper skarn deposits, porphyry copper deposits, shear-hosted gold deposits, epithermal vein deposits and gold placer deposits. Over 35 hard rock and 18 gold placer deposits are known within the area. Of significance are the Kathnell shear-hosted auriferous quartz veins; such structurally controlled veins may be more widespread than proposed prev-iously and offer a new exploration target.

Jan 1, 1994

By X Ma

Kaolinite is of very fine particle size in nature and thus its dispersion plays a key role in the successful removal of kaolinite in iron ore flotation and selective flocculation processes. As the most widely used dispersant in the world, sodium silicate has been used as a standard dispersant for kaolinite in the iron ore industry. However, the actual effect of sodium silicate on the colloid stability of kaolinite particles and its dispersion mechanism remain unknown in the literature. In this work, the dispersion effect and dispersion mechanisms of some common inorganic and organic dispersants, including sodium silicate, polyphosphate and a low molecular weight polyacrylic acid, on kaolinite particles were systematically investigated through electrophoretic mobility and colloidal stability studies over a wide pH range. It was found that sodium silicate-kaolinite interactions only take place in the neutral and acidic pH range, while polyacrylic acid and polyphosphate interact with kaolinite from pH 3 to 10.5. Consequently, sodium silicate only disperses kaolinite at neutral and acidic pH. In contrast, polyacrylic acid and polyphosphate disperse kaolinite from pH 3 to 10.5, with strong dispersion effect observed at neutral and acidic pH. In the iron ore industry, selective fl occulation and reverse cationic fl otation, the most widely used flotation route, are both conducted at pH 10 to 10.5. The results of the present study show that, at such high pH, polyacrylic acid and polyphosphate are more effective dispersants of kaolinite, in comparison with sodium silicate.

Jul 11, 2011

By P B. Hills

Almost a quarter of a century since Bridges (1993) documented techniques for the assessment of ground conditions in a seminal paper in the Proceedings Second International Mining Geology Conference, the necessary role of the geologist in recording geotechnical data on exploration properties and in mines remains. Typically, the geologist is the first professional on the exploration property. Of course, most exploration properties don’t become mines. However, when a property does start to come together and form a coherent mineral deposit and professionals from across the minerals industry spectrum, including specialist geotechnical engineers, become increasingly involved, it remains the geologist who has the most intimate knowledge of the deposit. By association, that knowledge extends to the character of the rock mass.Throughout the various phases of prefeasibility, feasibility, construction and production, culminating in the mature mine, the knowledge of the rock mass held by the geologists continues to grow. In the current era of minimising cost and optimising profit, meeting the requirements and expectations of stakeholders ranging from fellow employees to investors, industry and financial regulators and the broader public, in a social environment where occupational health and safety concerns are of uppermost concern in every endeavour, the value of the geologists’ observations cannot be understated. Mines nowadays employ more geotechnical engineers than they did in the early 1990s when Bridges (1993) wrote his paper. More funds are available for specific geotechnical investigations of exploration properties and mines; none-the-less, those programs remain limited in their extent and there is a wealth of additional data available for collection with the appropriate training, at little additional effort. Fundamentally it is all about the numbers. Any hole not geotechnically logged is a hole that will need to be drilled again if the data is required. Any face, surface or underground, not geotechnically mapped is one that may need to be mapped a second time. That doesn’t mean every hole or every face. However, it is the proposition of this paper that the opportunity for additional geotechnical data to be gathered during traditional geological investigations is an opportunity that cannot be ignored. Occupational health and safety requirements demand that the geotechnical risks associated with mining are appropriately managed. Mining regulations in most Australian and overseas jurisdictions requires the consideration of geotechnical risk through formalised management plans. The Joint Ore Reserves Committee (JORC) Code requires the consideration of modifying factors more than ever before. The benefit to be realised through improved geotechnical understanding by geologists on the ground leads to improved occupational health and safety, optimised reporting compliance, and improved financial and social outcomes for the exploration property and ultimately for the mine that follows.CITATION:Hills, P B, 2017. The necessary role of the geologist in geotechnical data gathering, in Proceedings Tenth International Mining Geology Conference 2017, pp 347–354 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By W Newton, J Price

This paper outlines the design, justification and performance of a gravity circuit upgrade at the Marvel Loch treatment plant. The design of the upgrade was simple but effective. The key components of the upgrade were the addition of a sluice and a second Knelson Concentrator. The sluice was installed as a pre-concentration step. The upgrade also included the purchase of a Mineral Cone to treat the increased quantity of gravity concentrate. The cost was low because of the use of mostly second-hand equipment. The result was that for a cost of $75 000 the gravity recovery doubled and the overall recovery increased by over one per cent. This paper shows that you do not need to spend millions of dollars to be innovative and successful.

Jan 1, 2000

Revegetation at Perseverance Mining's Nagambie Gold Project is an excellent example of cost effective revegetation in the Central Victorian Goldfields. Work has centred on waste rock dumps, vegetative screens, amenity planting and revegetation trials on cyanide heap leach pads. A wetland is under construction and in consultation with farmers, waste heaps were planted with perennial pasture species.The area treated to date is 18 hectares comprising: 16 hectares of pasture and two hectares of trees/understory. Direct seeding and tubestock planting has cost $16,464. Cost effective revegetation demands careful planning from the EES stage onwards. The Government agreed rehabilitation plan should be comprehensive, realistic and above all flexible. This document must be kept in mind during the mining operation.

Jan 1, 1992

By Newell R

The situation in which a gas stream flows through a bed of solids is found in many extractive metallurgy operations. Examples include blast furnace smelting, sintering and pellet firing. In such cases the resistance of the bed to fluid flow and heat transfer is of major significance to the operation of the process. This depends on the structure of the bed, which in turn is influenced by the manner in which the materials are charged to the bed. In this work, packed beds of hematite pellets of two different sizes were prepared in which the pellets were charged as a uniform mixture and in layers. The porosity, flow resistance and heat front velocity were measured and compared for the different bed configurations. For layered beds, the overall porosity and heat front velocity increased while the flow resistance decreased when compared with the values obtained for the uniform mixture. The size of the layers also had an effect on flow Properties.

Jan 1, 1991

By Yigit E, Royston D, Winborne DA

Semi-bulk concentrates of 45% zinc at 80% recovery have been produced from the McArthur River mineral deposit. Selective leaching of these concentrates to recover lead and a commercial grade zinc concentrate has the potential to increase significantly the recovery of zinc (as zinc concentrate) and lead (as lead metal) over conventional flotation methods producing lead and zinc concentrates.

Jan 1, 1986

By C Harwood

Underground coal mines in the United States are in the process of completing installations for tracking and communication systems, mandated by Congress after a number of recent coal mine disasters. Yet, evaluation, modelling and testing of such systems has lagged due to legislated changes, abruptly introduced into the coal mining industry. System installation in a wide array of mine types, configurations, layouts and characteristics has provided a wealth of information regarding their potential in underground environments. Data collected from numerous installations for a variety of systems can be used to further define true capability and accuracy of communication and tracking packages. This paper describes a uniform means of evaluating the performance of a communication and tracking system. Several performance measures are proposed and described. These measures can also be predicted using an interactive software program. This program predicts the signal propagation, given the input mine characteristics and layout, with numerical and visual feedback. New or alternative system installations can also be more accurately designed to potentially minimise initial system cost and time required for trial and error installs. The focus of this research is to develop tools and protocols that can evaluate and measure the effectiveness of installed underground communication and tracking systems.

Nov 22, 2011

By S Lee, I Sohn

The ferrous and non-ferrous metallurgical industries have been utilising slags, fluxes and mattes for process optimisation and quality improvements at high temperatures. Understanding the fundamentals of the thermodynamics and kinetics of chemical metallurgy regarding slags, fluxes and mattes has been essential to the technological developments of these optimisation and improvements. This work will discuss how these fundamentals have been studied in the reactions involved and implemented in the ferrous industry from primary refining to continuous casting. In particular, the chemical driving forces that allow these reactions to take place and the limitations of the kinetics that require optimisation to enhance the reactions. In addition, the future research direction for slag technology innovation and the role of these fundamentals will also be described.

Jun 19, 2024

By J Rayner, R P. Langmead, J A. R Coote

Gosowong is situated within the Neogene magmatic arc of Halmahera island in the Maluku province of eastern Indonesia. It was discovered as the result of a rigorous ground reconnaissance program in an area with no previous mining activity. The broad structural setting in the Gosowong District comprises an elongate dome formed by the forceful upward intrusion of magma along a deep-seated structure, resulting in associated tensional fracturing trending parallel to the long axis of the dome. Four copper-gold porphyries and numerous low-grade epithermal veins occur within this mineralised corridor, with the Gosowong Deposit being the only economic occurrence discovered to-date. Gold mineralisation is hosted within multiphase epithermal quartz-adularia and quartz-chlorite fissure veins, breccias, and stockworks. High-grade gold mineralisation is emplaced in two gently south-plunging ore shoots along a 400 m section of the north-striking, east-dipping, Gosowong Fault, the primary control on mineralisation. The Gosowong Fault is believed to be a tensional fracture associated with uplift of the dome. Lithological variation and structural intersections play a large role in grade distribution within the vein zone. Host rocks comprise a wide range of shallow marine, intermediate-basic volcanic and volcaniclastic rocks of ?late Miocene age. The Gosowong gold deposit is a classic example of a low-sulphidation epithermal gold deposit, based on the abundance of adularia and illite in the alteration assemblage, and low base-metal sulphide content within quartz-adularia veins. The indicated resource is estimated at 0.99 Mt at 27 g/t Au and 38 g/t Ag for a total of 870 000 ounces Au, using a cut-off grade of 2 g/t Au.

Jan 1, 1999