Search Documents

By Chamberlain A. C, Fisher N, Avraamides J

The thermal decomposition of sodium ethyl xanthate (SEX) adsorbed onto activated carbon was studied by coupled thermogravimetric analysis-Fourier transform infrared spectroscopy (TG-FTIR). Two discrete mass losses were observed, in the temperature ranges 100 - 230¦C and 200 - 340¦C. The same two gases, carbonyl sulphide (COS) and carbon disulphide (CS2), were the main gases evolved in each of the mass losses. Samples of activated carbon from two industrial plants were obtained and analysed by TG-FTIR. COS and CS2 were not detected in one of the samples. The other sample did show evidence of COS and CS2, which indicated that fouling of the carbon by SEX was still present. Other organic compounds were detected in the evolved gas stream of both samples, indicating the presence of organic reagents other than SEX.

Jan 1, 1996

The geological features of the destructive plate margins of the southwest Pacific favour the formation of porphyry type deposits. The major controlling factor favouring the formation of gold-rich deposits of this type is a dense crust. This results in shallow intrusion of large magma bodies beneath andesite stratovolcanoes. Where the intrusives have near vertical sides, the comparatively low temperature of transfer of volatiles from the solidifying melt favours the partitioning of gold into bubbles of volatiles. They reduce the viscosity and density of the melt, resulting in the upward movement of a mineralised melt. With the drop of pressure with upward movement the bubbles separate into a two phase mixture, triggering freezing of the mineralised melt and the formation of a gold mineralised stockwork.

Jan 1, 1995

By M Stewart, J Vann, S Dunham

Geometallurgy is an emerging, cross-disciplinary field that integrates spatial models of rock properties with time-based outcomes of mining and treatment processes. Geometallurgical variables include any rock property that has a positive or negative effect on the business. Some of the more critical geometallurgical variables include recovery, grindability, throughput, power consumption, mineralogy and content of deleterious materials. These variables drive project costs and revenues in a fundamental way and thus geometallurgy has potential to positively impact on the value of strategic and tactical decisions across many mining organisations. Geometallurgical models, like traditional grade-only models are based on samples collected from the mineralised and non-mineralised regions of the deposit. The nature of some non-grade variables, particularly those that are dependent on the ore treatment processes, requires special consideration during sampling and subsequent spatial modelling. Failing to objectively consider the characteristics of variables may seriously compromise the validity of the sample selection, sample treatment, data models and the subsequent decisions. In addition to addressing the vexed question of collecting an æunbiased and representativeÆ sample, the sampling and modelling approach must consider issues of scale, both geostatistical support and also the relationship between bench-scale data and operational-scale mineral processing performance. This paper proposes a framework (the Primary-Response framework) for the classification of geometallurgical variables. This framework is designed to assist with developing sampling approaches and identifying the most appropriate spatial modelling approach. The proposed framework can also help identify the risks associated with designing, sampling and modelling of both types of geometallurgical variables. The Primary-Response framework divides variables into two categories; primary variables and response variables. How a variable is classified in this framework depends on the degree to which the variable reflects either an intrinsic attribute of the rock (æprimaryÆ) or its response to measurement processes (æresponseÆ). Depending on the classification in this framework, appropriate sampling and modelling decisions can be made to minimise the risk associated with the incorrect treatment of the variable. In particular, the authors argue that for response variables, the approach taken to building spatial models may need to be different to conventional linear averaging approaches (for example kriging).

Jan 1, 2009

The paper is introduced by some general comments on the Electrolytic Zinc Company West Coast Mines operations. An outline of the geology of the Rosebery Mine orebodies preced- es a resume of the mining methods used prior to the current mechanization programme. The reasons for the introduction of longhole stoping techniques are given together with a brief explanation of both sublevel longhole and longhole stoping methods. The application of remotely controlled loaders within these stoping methods is discussed. A description of the remote control mechanisms, used on Atlas Copco 310 and 511 Cavo loaders, is followed by comments on these mechanisms from both a maintenance and production viewpoint. A summary of perform- ance statistics and operator safety records vindicate the selection of remotely controlled loaders for the longhole stoping areas at Rosebery Mine.

Jan 1, 1977

Water rights and availability are extremely contentious issues in many mining regions around the world, in some instances leading to violent confrontation. This situation has the potential to only get worse because competition for 'scarce' water resources will increase with population growth. In this environment the dilemma facing the mining industry is how to generate confidence in developing a responsible, sustainable and transparent water management strategy that is recognised as such by all stakeholders. Whilst the water needs of the mining industry are minor compared to those of agriculture, an operating mine requires a relatively large quantity of water on a daily basis to carry out operations. Another contentious aspects of new mine development is the debate between all stakeholders on the amount and quality of water that a mine is able to discharge into the environment should this be required. There are a multitude of water resources available to the mining industry for operational needs however much of this water is saline and over the last two decades there has been a continual decline in water quality (ie salinity has increased). In today's world there are enormous internal and external pressures to reduce water consumption at a mine and/or alternatively use water not considered a resource by the local community (ie sewage, saline or salt water, desalinated water). Strategies to meet these objectives can be achieved by implementing good water management practices, by recycling process water, reducing water losses by evaporation and seepage (ie by increasing and improving dewatering practices) and employing new technologies such as dry stacking and dry processing. Recycled water, acid mine drainage water and water collected in the mining area have the potential to impact mineral processing performance, unless they are treated, because of the build up of mineral salts and decomposed chemical products in these types of waters. Besides this the regulatory requirements of any water discharged from a mine site (quantity and quality) have also become more stringent. For these reasons there is now some form of water treatment practiced at most mining operations around the world. This paper provides an overview of water stewardship undertaken in the mining industry over the last two decades and provides examples of water treatment practices that have recently been installed at mining operations that may be of interest to the reader.

Sep 13, 2010

CONTENTSSummaryIntroductionGeographical and Geological Outline of the RegionGrowth of the Mining IndustryTable 1: Production StatisticsGeneral GeologyRecent Alluvium and River GravelsSambeto SeriesMudstone and Basalt ContactVatukoula SeriesIntrusivesStructureGeologic HistoryLodesTable 2: Principal Lodes and Their OrebodiesMineral Assemblage and ParagenesisOre Shoots and Their ControlEmperor MineLoloma MineDolphin MineExplorationConclusionAcknowledgmentReferencesSUMMARYThe Tavua Goldfield was found in 1932 within a basin, both topographical and structural, near the sea on the north side of Viti Levu, Fiji, and has produced over £13,000,000 (Fijian) worth of gold and silver from the three mines...

Jan 1, 1953

Geological Parameters Controlling the Improvement of Manufactured Sand Using Vertical Shaft Impact Crushers Instead of Cone Crushers Natural sand is a limited resource. In Sweden the total use of natural sand and gravel is around 20 million tonnes per year and the goal is to halve the use of this resource in the near future. Most of this natural sand is used for concrete production, so the consequence of this goal is that more and more concrete must be produced with manufactured sand. The bedrock of Sweden consists mainly of granites and gneisses, rock types mainly composed of various amounts of quartz, feldspar and mica. Manufactured sand from these materials generally contains rather flaky and elongated grains, and there are few types of granite that can be used as manufactured sand in concrete without increasing the amount of cement by eight to ten per cent. A Vertical Shaft Impact crusher (VSI) is commonly used to improve the shape of coarse aggregate particles. Research has shown that it is even possible to improve the shape in aggregate fractions less than 1 mm for some rock types. The aim of this project was to investigate which geological parameters control the improvement of manufactured sand when using VSI-crushers instead of the traditionally used cone crusher. In order to do this eight rock types of granitic composition were investigated. The selection of rock materials for the tests was based on grain size and mica content. A 4 - 8 mm fraction of each material was used for the tests. The characterisation of the shape of the material was performed using image analysis applied on microscopic images. The results showed that the VSI-crusher had improved the shape of all materials down to 0.036 mm, except for one rock sample. According to these results granites with low mica content and relatively high content of feldspars have the best prerequisites to produce manufactured sand for concrete with suitable geometric characteristics, and if these materials are crushed with a VSI crusher they almost show the same characteristics as natural sand.

Sep 13, 2010

By Rajan S, Mainwaring P, Gould WD, Beaulne M

Polished discs of a complex sulphide ore were leached with three lixiviants; a mixed culture of Thiobacillus ferrooxidans and Thiobacillus thiooxidans, Thiobacillus ferrooxidanalone, and ferric sulphate. At either one or two week intervals the discs were examined by scanning electron microscopy, and the amount of soluble metals released from the discs were determined. The mixed culture solubilized more Cu, Zn and Pb than did either ferric sulphate or T. ferrooxidans alone. However, no differ-ences were observed between the three treat-ments by scanning electron microscopy during the first 44 weeks. The minerals were attacked in the following order: pyrrhotite, cubanite, sphalerite, pyrite and chalcopyrite.

Jan 1, 1990

Computer-based block modelling of orebodies is now used at Renison Tin mine for the estimation of ore reserves. It is considered that this has resulted in improved reserve estimation for complex 'stratafault' orebodies. The results for all orebody types are more easily understood by the mine planning section and provide greater scheduling capability than those from the previous manual isoline reserve estimation method. A structural overview of the deposit can be gained by combining geological block models for the various orebodies. It is anticipated that upon completion of block modelling for all the orebodies the time spent on the annual ore reserve estimate will be significantly reduced.

Jan 1, 1990

Jan 1, 2004

By J A. M Luz, A T. Bernardes

HukkiÆs law is an empirical law, which does not take into account several events of energy loss during the fragmentation processes. Since experimental results are very difficult to obtain, for a large range of fragment sizes, the verification of the law is very difficult. The relation between fractures and fragmentation processes with fractal geometry was proposed some decades ago. Empirical laws known in this context show basic features of fractal geometry, mainly self-affinity and power law behaviour. Thus, in this work a model was developed to simulate the fragmentation process and to check the relation between energy consumption and fragment sizes. The model is represented on a regular lattice. Links can represent pathways for fracture processes. The events of fragmentation have energy given by a probability distribution function. In the model there is no mass loss. Propagation of fractures occurs as self-avoiding random walks on the regular lattice.

Sep 26, 2011

By P J. Bangerter, J Pan

Optimising for Net Present Value (NPV) with a strategic optimiser such as COMET, Prober-E, Blaser or Minemax has hitherto lacked a dynamic method for analysing the so-called third-order outcomes (such as Carbon emissions) of optimisation within life-of-mine planning. Optimisation, per se, has natural effects on carbon emissions in a life-of-mine plan. Contemporary strategic planning employs a mathematical optimiser to make sense of non-linear data (ie a block model) and produces a best-NPV optimised mining schedule, within a set of constraints. The very act of optimisation influences emissions, and in a dynamic way.

Aug 2, 2023

By Davey CJ

An integrated computer software system has been developed by Fluor Australia for modelling, mine planning and production scheduling of single or multi-strata deposits. Modelling of both quantitative and qualitative variables (e.g., thickness, basal elevation, density, grade/ash content) is performed via continuous, minimum curvature surface representations. These may be developed from inverse distance weighting or geostatistical kriging interpolation techniques in conjunction with bicubic spline surface interpolation. The modelling process, rather than being purely mathematical, incorporates facilities for reflecting structural geology interpretations (e.g., faulting, pinchouts) and geological boundary conditions (e.g., subcrop and outcrop). Volumetric programs provide the facility for continuous integration over models (at any specified integration increment) for any number of specified irregular polygonal panel areas or regular rectilinearly defined block plan areas. Multi-variable integration is available, incorporating any or all operations of addition, subtraction, multiplication and division to provide multi-strata tonnages, etc., (e.g., Volume 1 * density 1 + Volume 2 density 2). These programs provide true three-dimensional integration with the facility for calculating results on an area by area, level by level, strata by strata as well as overall basis.

Jan 1, 1983

By D C. Verdon-Kidd, G R. Hancock, M J. Saynor, J B. C Lowry, T J. Coulthard

Designing post-mining landscapes requires quantifying the short and long-term risks. In recent years, computer based landscape evolution models (LEMs) have been used to provide insight into both erosion rates and processes (i.e. sheetwash, rill, gully erosion). An important requirement of these models is high quality model input parameter data, which includes both the surface material (i.e. soil and waste rock) and climate information. However, in many cases such data is limited and in the case of climate information, the data is often short and incomplete. Here we develop climate scenarios and examine different surface material properties using a case study at the ERA Ranger mine located in the Northern Territory, Australia Firstly we develop scenarios that represent the range of future climates that may be experienced at the site. Secondly we develop a series of plausible particle size distributions based on a large sampling exercise of the waste rock material. We then test the sensitivity of different rainfall sequences and surface materials on sediment output using a well-tested landscape evolution and sediment transport model (Hancock et al., 2017). CITATION:Hancock, G R, Verdon-Kidd, D C, Coulthard, T J, Lowry, J B C and Saynor, M J, 2018. Quantifying the effect of climate and surface materials on post-mining landscape erosion – a risk approach using landscape evolution models, in Proceedings Life-of-Mine 2018, pp 122–124 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By N Stockton

Some preliminary results on the secondary leaching of previously heap leached gold ore are presented. Alternative lixiviants for gold comprising chlorine, thiourea and thiosulphate were compared with cyanide using bottle roll tests. Chlorine was subsequently selected for column leaching tests. Column tests at 1.0, 0.1 and 0.01 gL-1 Cl2 at pH 2 were conducted. The results indicated that about 23 per cent of the gold was leached over 45 days using 1 gL-1 Cl2 at pH 2. The experiments conducted proved that the chlorine/chloride system has good potential for further extraction of gold and silver from the existing cyanide heap leach residues and a process for secondary leaching of gold has been proposed. Further testwork is recommended to extend conditions, sample types, and the duration of leaching period.

Jan 1, 2000

Relationships between lead blast furnace performance and the composition and size distribution of sinter were determined from analysis of lead blast furnace operating data. Sintering plant practice was subsequently modified and substantially improved furnace performance resulted.

Jan 1, 1971

With the recent wider introduction of friction hoists of the Koepe type. for winding from depths of more than 3000 feet it has been found that failure by fatigue is the most common form of rope deterioration. Large numbers of wire breaks occur near the centre of the rope cross-section and it is difficult to detect these with certainty using the preferred d.c. magnetic test. For best results with conventional search coils their dimen- sions should be related to the typical wire break field pattern surrounding the longitudionally magnetised rope. The field of a broken wire was experimentally determined, using a Polish type MD6 Defectograph wire rope testing magnet and a short prepared length of rope with a movable simulated broken wire. The external field distortion perpendicular to the rope was measured by means of a gaussmeter and Hall probe. The advantages of this method are that terrestial magnetism and inherent rope "noise" have no effect on the results.

Jan 1, 1971

The purpose of this paper is to outline the basic policy problems for good community relations programmes in the resource extraction industries of Papua New Guinea. The main focus of the paper will be on defining and analysing those problems which lie on the landowner side and which are still not widely understood within the resource extraction industries despite several decades of turbulent experience. Many of the companies operating in the resource extraction industries of mining and petroleum and gas have in recent decades adopted, by choice or necessity, 'good corporate citizen' policies. Some of these companies now pursue ethical business, environmental and community relations policies. Some have adequately funded and well-trained staff in their community relations departments. Although different industry sites scattered over Papua New Guinea show significant differences in their experience of social conflict, I argue here that a good deal of this variation has less to do with the differences between the companies' public relations policies and their effectiveness and more to do with the conflict causing features of indigenous society. Experience suggests that even a company well-equipped with good intentions, good policies and good staff may experience serious difficulties in maintaining good community relations in Papua New Guinea. Many of these difficulties, I argue, can be traced to causes that lie, essentially, within the structure of Papua New Guinean communities and in the customs and social relations of Papua New Guinean peoples. Accordingly the attention of this paper is focussed on the conflict causing aspects of Papua New Guinean society. It is true, to the point of being a cliche, that Papua New Guinean societies are oriented very strongly towards achieving consensus and social harmony. In this regard Papua New Guinean communities differ significantly from, say, Australian communities. My purpose here is not to denigrate this aspect of Papua New Guinean societies but, rather, to point out that the drive for consensus is driven by the desire to avoid its opposite, dissensus. This paper sets out to define the dissensual aspects of Papua New Guinean societies and my special interest is in those conflict producing aspects of Papua New Guinean societies that are most resistant to the mechanisms that are designed to create social harmony. A survey of the recent history of industry and community relations in Papua New Guinea indicates that there are three main factors present on the landowner side which are liable, separately or through their interaction, to cause difficulties. These factors are respectively generational challenge, social boundaries and custom variability and I shall discuss each of these in turn.

Jan 1, 1997

By W Lunwongsa, S Meffre, S Nuanla-ong, K Zaw, R James, A Salam

Gold and silver mineralisation at the Chatree low sulfidation deposit is hosted in andesitic volcanic and volcaniclastic rocks and characterised by multiple hydrothermal alteration assemblages and quartz-carbonate (chlorite-adularia) replacements, veins and breccias. The ore-bearing veins are influenced by intersecting structures and host rock lithologies. Emplacement of the host succession occurred at 250 ¦ 6 Ma (dated with laser ablation ICP-MS U-Pb zircon techniques), which was closely followed by mineralisation at 250.9 ¦ 0.8 Ma based on the analysis of adularia from coarse-grained quartz-sulfide (chalcopyrite-pyrite- sphalerite) veins using laser ablation Ar-Ar methods. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By R F. Weinberg, R A. Armstrong, A G. Tomkins

We investigated the duration of formation of the giant Ok Tedi porphyry copper-gold deposit in Papua New Guinea using zircon SHRIMP U-Pb dating. The intrusions that host the Cu-Au mineralisation have a maximum age of 1.43 ¦ 0.22 Ma. Since previously published K-Ar dates on the same intrusion constrain the last thermal event at 1.11 ¦ 0.05 Ma, we conclude that the magmatic-hydrothermal event that produced the deposit lasted ~0.45 million years (Myr). A comparison of Ok TediÆs calculated volatile fluxes with those from arc volcanoes and active mineralising hydrothermal systems suggests that the efficiency of metal deposition is a key factor in determining the duration of deposit formation. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008