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Tougher physical mining and processing conditions as well as economic circumstances are causing many mining companies to re-evaluate the effectiveness of their mine planning. The recent wave of inexpensive computing power provides the engineer an opportunity to go beyond the simple one-off manual mine design and production schedule. The basis of a good mine plan is a good reserves model. Concepts of mine model development are explored. The only advanced computer methods that have found consistent success in optimising mine planning functions are economic pit limits determination and material scheduling. Three pit 'optimisation' methods are examined; the moving cone, the Lerchs-Grossman 3-D graph algorithm, and the new network flow algorithm. A comparison between the methods in terms of total profits generated and computer time involved are made. The results show that both algorithms produced a higher profitability than the simple moving cone, but at much higher execution times. However, the profit increase never exceeded much more than 1 % of the base moving cone case. Finally, a method for the development of long range material production schedules with forward waste planning is presented.

Jan 1, 1989

Located 350 km west of Sydney and 20 km outside Orange, NSW, lies the Ridgeway Gold Mine û NewcrestÆs flagship Underground Gold Mine. Key to success at Ridgeway has been the fast tracked development of the 3.8 km, 1 in 5.3 conveyor decline which houses the 850 t/hr conveying system feeding the dedicated Ridgeway Concentrator, built adjacent to the existing Cadia Hill Concentrator. Eroc was contracted to develop the steep conveyor decline, drawing on its personnel and experience from past metalliferous, tunnelling and coal mining projects to complete the ambitious schedule within 12 months. This paper deals with the complexities and experiences in safely delivering what is understood to be one of AustraliaÆs steepest declines of any substantial length in a metalliferous mine.

Jan 1, 2002

By Baafi E. Y

Dragline monitoring systems are normally the best tool used to collect data on the machine performance and operational parameters of a dragline operation. This paper discusses results of a time study using data from a dragline monitoring syste

Jan 1, 1998

THE science of topography deals with the various natural and physical features of the earth's surface. These features are determined by the manifold constructive and destructive processes of nature, and their many diverse forms and characteristicsare dependent primarily upon geologic structure. Thus it is that a close relationship exists between the rocks of a region and the topographic features of the lJountry wherein they occur. Again, the existence of all sorts of mineral wealth is dependentupon the nature of the rocks, and their extension is directly connected with the topographic features represented upon the enclosing land-area.In studying any district with a view to deciphering its geological structure, to locating any mineral deposits it may contain, and to ascertaining, so far as a surface-examination may show, their probable and economic possibilities, it is therefore ofprimary importance to have at hand a correct topographical map of the area under investigation.GENERAL REMARKSThe actual amount of topographic detail shown will depend upon the money and time available for topographic surveying and upon the scale upon which the final map is to be produced...

Jan 1, 1912

By J N. Moncrieff

The resource estimation process for the underground Mount Isa Copper Mine has undergone significant change. Block models are now created using a commercial software package as opposed to the in-house software that was previously used. With mineralisation occurring over a strike length of more than 4 km, Mineral Resources for all categories totalled 190 Mt at 2.7 per cent Cu at 31 December 2002. Estimation is by ordinary kriging with two separate models generated to cover the X41 and Enterprise orebodies respectively. The underlying Upper Basement Contact and the silica-dolomite alteration envelope are both used as hard boundaries to constrain the modelling. From a validated block model, grade shells are generated at the appropriate cut-off grade for a given area. The grade shells are depleted for mined voids and subdivided into 30 metre strike length blocks. Application of a SMU criteria and crown and pillar constraints results in failed blocks being culled from the resource inventory. Mineral Resource blocks are further subdivided into resource categories (Measured, Indicated, Inferred) by the Competent Person on the basis of geological confidence, taking account of geological and grade continuity, drillhole spacing and structural complexity (JORC, 1999). A geostatistical æconfidenceÆ category is incorporated into the block model as an additional tool for the categorisation process. The shapes are assessed in concert with a mining engineer to determine whether a reasonable expectation of mining potential exists and if not they are removed from the resource. The final categorised blocks constitute the Mineral Resource inventory and form the basis for conversion to Ore Reserves. The resultant Mineral Resources and Ore Reserves are reported on an æinclusive ofÆ basis.

Jan 1, 2003

By G J. Lyman, S A. Tittlemier

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

May 9, 2017

A Simulation Study on Two-Stage Grinding with High-Pressure Roller Mills By the application of high-pressure roller mill (HPRM) in the field of mineral processing, computer simulation can be used to predict overall performance of a grinding circuit based on data obtained from HPRM comminution test in pilot scale or industrial scale. Using the model developed by Klymowsky and Liu for HPRM comminution and an extended Plitt's model for classification, steady-state of a closed circuit grinding can be calculated by means of a virtual locked-cycle-test conducted on computer. This paper presents the result of a simulation study on two-stage grinding with HPRM as the comminution device. The emphasis is put on the influences of circuit-configuration and way of recirculating classifier's coarse-product on the overall circuit performance. The results show that two-stage grinding with HPRM has its merit and flexibility in meeting demands of various grinding tasks in mineral processing.

Sep 13, 2010

Safety and health at work is about people. It is about people who plan for work, organise work and perform work. It is about those who come in contact with the workplace and those who are responsible for the workplace. There are wider ranging safety and health obligations that are imposed on the industry stakeholders that span all phases of the production process. In all cases, those responsible for discharging the obligations must ask the questions: Is what we propose safe?, can it be done safer? and are we sure? What we learn from recent legal cases before the courts is that it is essential that all stakeholders work together in a collaborative way when discharging these obligations. Safety and health at work cannot become an issue that is viewed only through the eyes of a single stakeholder group. The reason for this is quite simple. The interrelatedness of the responsibilities that are imposed on each of the stakeholder groups, means that the performance based legislation simply wont work, where an active model of communication and consultation is not in place.

Jan 1, 2005

By M Schaffer, T Kewe, N Moffatt

Porgera mine is 95 per cent owned by Barrick Gold Corporation. It is located at an altitude of 2200–2700 m above sea level in the Enga province of Papua New Guinea and produces approximately 460 000 oz per annum with a proven and probable reserve of 6.2 Moz. The refractory ore is ground in a conventional semi-autogenous grinding and ball mill circuit. After the gravity gold is recovered, the slurry is floated, oxidised in the autoclaves and then leached. This paper will focus on the flotation circuit and the recent upgrade of the control system. The five interdependent flotation circuits were challenging for operations to control as they dealt with variable grade, throughput and circulating loads, as well as the physical limitations of the equipment. With the installation of 18 Portage Froth Characterization® (PFC) cameras, the plant’s operation has been converted from a level-control based strategy that was focused on individual cells to one that targets grade and recovery control across the entire circuit. Variability in feed and the corresponding launder issues were addressed with a unique site initiative of deflector plates to indicate filling level. Non-linear closed loop control was implemented directly in the DeltaV Distributed Control System (DCS) using Portage Advantage Regulatory Control (PARC) algorithms and optimised with AwaRE advanced controllers. The most noticeable benefits achieved with the upgrade include improved flotation gold recovery, consistent flotation sulfur grade and autoclave performance. Correspondingly, there was a significant drop in boiler diesel fuel usage and launder overflow conditions.CITATION:Kewe, T, Moffatt, N and Schaffer, M, 2014. Porgera flotation circuit upgrade and expert system installation, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 345–356 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

Reason Analysis of Impurity Containing and Technology Discussion of Quality Improvement for Low-Quality Iron Concentrate

Sep 13, 2010

A model has been developed as part of the AMIRA P420 Gold Processing Technology Project to simulate the recovery of gold by centrifugal gravity devices. The model (which is available online) uses the simulation methodology developed by Laplante et al (1995) to predict gravity recoverable gold (GRG) recovery under varying operating conditions and circuit configurations. In addition to predicting GRG recovery, the model also predicts the GRG content and size distribution of the cyclone overflow and underflow. The predicted overflow GRG content and size distribution can be used as inputs for a leaching model in which size dependent leaching rates are applied for each size class of GRG and non-gravity recoverable gold (non-GRG) in the cyclone overflow, allowing size-by-size leach recoveries to be determined for GRG and non-GRG. The application of the gravity model and leaching model are demonstrated using a case study. The simulated gravity recovery and leaching performance showed excellent agreement with the measured values. The developed models can be used to assess the sensitivity of gravity gold and leach recoveries to varying feed GRG content, GRG size distribution, gravity circuit feed rate, classifier performance and leach residence time. The described methods can be used to optimise new and existing gravity and leaching circuits.

Aug 1, 2010

By M Coleman

Information is a key ingredient for successful mineral exploration and development. Whether identifying potential exploration localities from a map, interpreting technical reports or searching a register for operators past and present, the common aim is a parcel of information from which the enquirer can make a decision. Traditional information gathering often requires days or weeks of manual research, studying maps, files, reports etc, before consolidating the results into an investment proposal. In recent times, such methods have largely been replaced by Information Technology, making the process much faster, easier and more centralised. However, notwithstanding some very successful technology implementations, the general rush to computerise everything in sight has left many organisations struggling to cope with the management of large volumes of diverse information. Information management is now recognised as the most important factor in determining the success of information technology implementation. The Northern Territory Department of Mines and Energy (DME) has established a detailed information management strategy to underpin the rapid advance of computer technology within the organisation. A broad base of timely and reliable information is gradually becoming more accessible. It is envisaged that the availability of combined spatial, textual and scientific information will provide a sound basis for decision-making within the Department and the mining industry at large. Although information held by DME will be available at all times (24 hours on-line), its security and confidentiality will be guaranteed. The production of the DME system is aimed at satisfying the corporate objective to facilitate and promote mineral exploration and development. This paper outlines some current developments in the system.

Jan 1, 1994

By Boyd GL

Backfill applied to highwall mining is foreseen as a means to increase recovery of mineable coal to levels comparable with underground longwall mining. This paper describes the progress of research to demonstrate the role required of backfill to achieve real increases in coal rCCOvCrCd h\ hi'eh ss-all mining methods.

Jan 1, 1998

Extraction and Characterisation of Extracellular Polymeric Substances from the Mineral Surface During Bioleaching of Chalcopyrite Concentrate A mixed culture of moderately thermophilic microorganisms was used to bioleach chalcopyrite concentrate in a stirred tank reactor. The results show that up to 84.7 per cent of copper extraction could be achieved in 24 days at a pulp density of 6 per cent. The leaching rate of chalcopyrite concentrate tended to increase with an increase of dissolved total iron concentration. Furthermore, the extracellular polymeric substance (EPS) on the surface of the chalcopyrite concentrate was extracted and analysed. EPS was extracted at the first, third, eighth, 16th and 24th day during bioleaching, which mainly consisted of proteins, lipids, sugars and ferric irons. After the eighth day the total amount of EPS remained relatively constant. However, the amount of ferric iron in the EPS decreased in a large scale. The ore residue analysis indicates that the decrease of ferric iron was mainly due to the formation of jarosite on the mineral surface.

Sep 13, 2010

FOR many years past it has been the practice at the Bairnsdale School of Mines to treat any parcels of auriferous concentrates sent in from the surrounding district by roasting them in a handworked reverberatory, and then chlorinating or cyaniding the product. According to Donald CIark, who has done a large amount of work on these ores, the results obtained were fairly satisfactory extractions of over 90 per cent being claimed. With some modifications, the method has been very generally adopted, not only in Gippsland but throughout Victoria. It is, however, difficult to get exact information as to the extractions actually obtained, and unfortunately no records of working results have been kept at the Bairnsdale School of Mines.Having treated several lots of ore by this method during 1907 and 1908 with unsatisfactory results, the writers thought it desirable to make a detailed investigation on some particular ore, both in the laboratory and on a working scale. The ore selectedwas a parcel of low-grade concentrates from Stirling, a small mining field situated about forty miles to the east of Bairnsdale. This ore was chosen chiefly on account of the heavy and inexplicable volatilization loss which took place even on roasting with the greatest care; the loss amounting to between 10 and 15 per cent. In the experiments here related, three main objects were kept in view:-1. To determine with what mineral 01' minerals the gold and silver were associated...

Jan 1, 1909

In most States of Australia it is a legislative requirement for underground mines to have a separate means of egress from the normal means of ingress to permit the safe evacuation of workers to the surface in event of an emergency. Such egress may be in the form of a ladderway equipped shaft/underlie or trafficable incline/decline. Additionally, there is a general requirement to have one or more airways, separate to the main shaft or other principal entrance of an underground mine, extending to the lowest level to permit ventilation to all parts of the mine. Fulfilling these requirement is difficult in the development phase of a mine when access underground is achievable by only a shaft or decline in the process by being sunk. What is frequently practiced in Australia is for production to then commence, sometimes in association with continuing development, in the same configuration without the establishment of this separate method of egress to the surface nor additional airway/s with reliance on refuge chambers to cater for back up in any emergency. Not only, could this jeopardise the health and safety of workers in case of an underground emergency it could be construed as a statutory breach of legislation. While recognising that refuge chambers are often used throughout underground operations nowadays their equipping and the criteria for their location needs to be bought into focus. This presentation discusses how such legislative requirement can be met alongside the use and appropriateness of refuge chambers.

Jan 1, 1998

International tenders for contract mining opportunities require the Contractor to make an assessment of risk for an operation with a life span of up to twenty-five years usually based on data made available by the Client. This paper seeks to address how the Contractor assesses the data and quantifies the risks associated with the project. The areas of risk are common to most projects, but in the--Lontractor's case, risk assessment is carried out on the Client's data base and within a compressed time frame of usually less than six months. Incorporation of that risk assessment into the contract documentation is also discussed. Practical examples are given in a number of areas.

Jan 1, 1986

By G N. Musafer, M H. Thompson, R C. Wolff, E Kozan

The most important aspect of modelling a geological variable, such as metal grade, is the spatial correlation. Spatial correlation describes the relationship between realisations of a geological variable sampled at different locations. Any method for spatially modelling such a variable should be capable of accurately estimating the true spatial correlation. Conventional kriged models are the most commonly used in mining for estimating grade or other variables at unsampled locations, and these models use the variogram or covariance function to model the spatial correlations in the process of estimation. However, this usage assumes the relationships of the observations of the variable of interest at nearby locations are only influenced by the vector distance between the locations. This means that these models assume linear spatial correlation of grade. In reality, the relationship with an observation of grade at a nearby location may be influenced by both distance between the locations and the value of the observations (ie non-linear spatial correlation, such as may exist for variables of interest in geometallurgy). Hence this may lead to inaccurate estimation of the ore reserve if a kriged model is used for estimating grade of unsampled locations when non-linear spatial correlation is present. Copula-based methods, which are widely used in financial and actuarial modelling to quantify the non-linear dependence structures, may offer a solution. This method was introduced by Bßrdossy and Li (2008) to geostatistical modelling to quantify the non-linear spatial dependence structure in a groundwater quality measurement network. Their copula-based spatial modelling is applied in this research paper to estimate the grade of 3D blocks. Furthermore, real-world mining data is used to validate this model. These copula-based grade estimates are compared with the results of conventional ordinary and lognormal kriging to present the reliability of this method.CITATION:Musafer, G N, Thompson, M H, Kozan, E and Wolff, R C, 2013. Copula-based spatial modelling of geometallurgical variables, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 239-246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

Residual aeolian placers (RAPs) are formed by the wind, by preferential entrainment and removal of small and low-density detritusfrom a pre-existing, typically sedimentary sequence containing heavy minerals. Heavy minerals that are resistant to chemical alteration and either soft and malleable (gold), or extremely hard (diamond, sapphire, ruby, etc), are concentrated as a residual on the wind deflation surface, typically in the interstices between larger resistant clasts. RAPs form preferentially in arid or semi arid areas, where the vegetation is sparse or absent, and where topography and surface gradients are low, but may also form on beaches and in periglacial environments. RAPs consist of a continuous or discontinuous, planar or gently undulating horizon of heavy minerals in a single-clast-thick pavement of resistant pebbles, cobbles, or boulders, which mantles the present topography or palaeo-topography. Extreme wind erosion and surface deflation may condense the full pre-existing sequence into a layer of heavy minerals only. The grade of RAPs is substantially higher than in the precursor deposit, and commonly much higher than those typically found in most other placer types. Aside from their general occurrence as a thin pavement of resistant clasts, the best indicators of residual aeolian gold placers are the presence of wind-eroded stones (ventifacts) on the pavement, and the distinctive and unique shapes of aeolian gold grains themselves. The shape of the gold grains is progressively transformed by sand blasting during placer development, from grains with thickened rims, to toroidal grains on which the rims are æsplitÆ and peened inward toward the grain centre on one or both of the grain sides, to hemispherical or sub-spherical grains that are fully encapsulated by the in-turned rims. Gold that has undergone aeolian shape transformation is difficult to entrain and transport away from the site of aeolian concentration by anything other than mass movement or glacial processes. It is also easily retained by commercial recovery plants of any configuration.

Jan 1, 2004

Study on the Reasonable Mineral Processing Technology of a Cu-Mo Ore

Sep 13, 2010