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By K Williams

Marvel Loch South Pit has had a number of stages of open and underground mining activities before acquisition by Sons of Gwalia. The historical pit had achieved a completed pit depth of 150 metres and the shaft and decline mine had reached approximately 220 metres in depth using open stope mining methods. The various mining methods reflect the various economics and industry practice at the time. The South Pit ore zones are medium grade (~2.5 g/t) but have a regular geometry and large tonnes per vertical metre. A number of studies have been completed up to a pre-feasibility stage looking at options to extend the pit depth and to lower the unit cost of gold production. The options considered were the re-optimisation of the pit to determine further cutbacks or the innovative use of an in-the-wall ramp. The in-the-wall ramp (tunnel) would permit the removal of the in pit ramp to expose additional ore that was within the footprint of the ramp design and to provide the opportunity to increase the final pit depth. Similar mining method has only been used at Three Mile (Coolgardie, WA) and Chalice Mine (Norseman, WA). The tunnel would serve as a gateway for further extension of the south mine and the central ore zone via underground mining methods. The ultimate depth of the South Pit has been extended to 310 metres below surface and significant additional ore has been recovered. This paper will give an insight into the various studies to optimise the Tunnel mining method, the determination of the various tunnel dimensions, and the phases of mining to arrive at the completed design.

Jan 1, 2003

Sluice-boxes are by far the most widely used concentrating devices by small-scale operators in PNG who work alluvial gold deposits. The sluice-box designs and their operating conditions used are known to vary widely. The selection of sluice-box configuration and the operating parameters such as the water flow rate is purely based on past experience. Some use small flowrates to increase the fine gold recovery at the expense of efficient separations and capacity while others use high flow rates resulting in increased fine gold losses but with high throughput rates. Recent work has revealed that the combination of riffle height, their spacing and wash water flow rate are the most important parameters that determine the success or failure of such operations. This combination has been shown to depend on the in situ gold and gangue size distributions of the deposit being processed. This paper describes a design procedure which uses a non-linear optimisation method to determine the optimal combination of the above parameters to maximise the metallurgical efficiency of such operations.

Jan 1, 1993

Gold bearing sediments at Scotland Point occur within the Quaternary Gibbston Fonnation, which underlies Cromwell Flat in Central Otago. Gibbston Fonnation unconformably overlies Teniary Manuherikia Group clays, sands and quartzose gravels. Gibbston Formation sediments are composed of a texturally diverse, multistoried lithostratigraphic succession of sandy/gravelly/bouldery lithofacies, deposited within a multiple channel (braided) depositional environment. Lithostatigraphic analysis indicate an upward overall decrease in average grain size, reflecting a concomitant reduction in stream competence. This trend results from progressive channel abandonment as major distributaries avulse across the outwash plain. Grade distribution of alluvial gold is controlled by aggradational and to a lesser extent degradational lithofacies deposited as distinctive braid bar forms near the base of the sequence. These lithofacies were deposited at different topographical levels on the outwash apron, under variable hydraulic conditions. Recognition of large-scale auriferous bedforms within the braid bar depositional system coupled with an understanding of lateral facies relationships, allows headgrade control on run of mine ore and quick determination of overburden to ore ratios.

Jan 1, 1988

By J A. Didovich

Near the completion of undergraduate studies, students in mining-related courses are increasingly being presented the opportunity to undertake postgraduate studies. The current boom in the mining industry, the shortage of young professionals entering the industry and the lucrative starting salaries and packages on offer makes this a difficult and perplexing decision. This paper will outline what a PhD entails, discuss the benefits that a PhD can provide and discuss the timing and mode of a PhD.

Jan 1, 2006

By Sofoulis I

Recent studies in the Archaean of the Kalgoorlie-Norseman area show that the layered rocks can be subdivided into two main units, both containing basic igneous rocks and sediments. The lower unit is distinguished by the presence of acid volcanic flows and sills. In some areas, clastic sediments become coarser and,pas-s into conglomerates. This passage is accompanied by thinning of the beds. These features and their distribution suggest a basin of subsidence flanked-by areas of shallow-water deposition. -.

Jan 1, 1964

The Porgera gold mine has made significant progress with the successful installation of a JK FrothCam image analysis system. The system is used to measure and control froth velocity on the scavenger circuit which has brought significant economical and operational benefits. The froth velocity signal, determined by analysis of the camera, is transmitted to the PLC that manipulates flotation cell airflow rate and cell level controllers to maintain a target froth velocity of 130 mm per second. Following on from a three-week trial installation in June 2000, a permanent installation was commissioned on the scavenger Outokumpu (OK150) tank cells. Further work is in progress on the rougher Wemco cells. This paper describes the evaluation of FrothCam Technology and its subsequent installation.

Jan 1, 2003

By Y-B Kang, J H. Park, J Park

In order to understand the effect of oxygen injection into the molten metal on the valuable metals (VM) recovery and interfacial phenomena, several high-temperature experiments were conducted using a high-frequency induction furnace with a quartz tube as the reaction chamber at 1673 K. Copper-based waste printed circuit board (PCB) that contains some impurities was selected as the end-of-life resource. CaO-SiO2 based pre-fused slag and oxygen gas were used in present works. The composition change and microstructure of the samples were analysed. As oxygen was injected into the system, impurities were rapidly removed. After the removal of impurities, continuously injected oxygen lowered interfacial tension between liquid slag and liquid metal. Lowered interfacial tension induced Cu loss into the slag.

Aug 21, 2024

Mill liners provide the wear-resistant surface within grinding mills, they also impart motion to the mill charge, ie the grinding process, by providing the key between the charge and mill shell, and, at the discharge end, they remove the ground contents of the mill. As semi-autogenous grinding (SAG) mills have grown in size the process aspects of liner design and their impact on mill performance have become particularly important. While feedback from practical experience is critical to good mill liner design, increasingly sophisticated computer-based tools are being developed to assist in mill liner design.

Jan 1, 2007

Results of investigations on adsorption and desorption of CO M CH and a mixture of the two gases are described.4 Results showed that even when the equilibrium conditions contains 50% Co and 50% CH4, the gas emission in the initia' stages will contain as much as 80% CH . 4 The temperature has a small effect and so also particle size for 1.4-11.2mm. The ratio of CO2/CH gases adsorbed in coal samples depends upon t4he equilibrium pressure and this ratio decreases with pressure. Results of field tests support laboratory studies.

Jan 1, 1988

Wrenching between basement blocks is considered to be the mechanism whereby a well developed set of en echelon folds and an associated fracture system are developed in the Fitzroy Depression, Western Australia. The regular geometry of these structures accords with a right lateral regional coupling between high-standing, basement blocks bounding a trough filled with a thick pile of stratified Phanerozoic sediments. The structures developed during or after the Mesozoic Era, but the couple is inferred to have been applied to blocks outlined by old lineaments, which may reflect strains or ruptures in basement that developed during the Precambrian, and which were regenerated during Palaeozoic and Mesozoic time.

Jan 1, 1967

A narrow (200-300m) zone of amphibolite facies metamorphic rocks underlies the Papuan ophiolite near the Musa-Kumusi divide, SW of Popondetta, Oro Province. The amphibolite rocks are bounded up-section, to the NE, by peridotite and gabbro of the ophiolite; and down-section, to the SW, by mafic greenschist, which in turn overlies blueschist facies mafic schists of the Emo Metamorphics.Amphibole compositions within the narrow contact zone show a strong chemical zonation which reflects a steep thermal gradient, with maximum temperatures >800¦C at the peridotite contact. The zonation is recorded in Ti content and A-site occupancy, relative to Al'¦

Jan 1, 1994

Tasker (1985) has detailed the accepted practices for constructing polygonal blocks of influerrce in the estimation of ore reserves. Further he suggests that users might fall into traps such as omission or overlap when determining the area of influence for each sample point.As an example of these types of errors Tasker (1985) describes under "Coverage ofthe Area" how 25 per cent of the exploration area will not be included in an equiangular triangular grid where hexagonal blocks of influence are used.The introductory suggestion of Tasker (1985) of "incorrect procedure" by Rudenno (1983) (and Armstrong (1983)) reiterated around the Figure 2a of Tasker (1985), is based on the brief description of the polygonal area of influence by Rudenno (1983). That description is not too different from that given by King, McMahon and Bujtor (1982).

Jan 1, 1985

The paper is aimed at mining engineers and other mining practitioners in the metalliferous mining industry who are considering the use of roadheaders and wish to understand the basic geomechanical and operational principles controlling their performance. The paper aims to address metalliferous minersÆ general unfamiliarity with roadheader technology, which is one of the factors which has limited the application of these machines in such mines. The historical development of drag tool mechanical excavation machines is briefly discussed, and factors affecting the application of roadheaders are mentioned. The mechanics of cutting with drag tools is then reviewed as are the effects of these and tool wear on tool performance. The implications of tool performance to roadheader performance are mentioned, the potential benefits of high pressure waterjet assistance are discussed and the relative performances of different tool types and materials are compared. Roadheader performance factors including productivity and utilisation are mentioned, and the state-of-the-art of conventional roadheaders is discussed in the context of machine weight, power and cutting head configuration. The influence of these and rock strength on machine productivity is analysed. Alternative, developing technologies are discussed which may extend the effective use of mechanical excavation into stronger rock masses which are beyond the range of conventional roadheaders. Finally, conclusions on these discussions are presented, along with recommendations for continuing research and development.

Jan 1, 1997

By R A. Bearman

Recent demand pressures for iron ore should not distract from the longer term view that intense competition in the industry has demanded technological innovation of a high order. There is a long track record of successful innovation underpinned by a solid base of scientific research and knowledge. By comment on recent developments in trucks, comminution and direct smelting, this paper suggests that innovation is still a key attribute of the industry. The spending of the minerals industry on underlying science, however, is not particularly high. By looking at other industries we can ascertain that for step change technologies, it is particularly advantageous to have a solid base of science and technology underpinning developments.

Jan 1, 2005

By R H. Yoon, M Gupta, A Noble, K Huang

Froth flotation is the most commonly used separation technology in the mineral industries. Given the complexity of the pulp and froth phases as well as the multitude of operational parameters that influence flotation performance, purely fundamental models with strong predictive capacity are limited. As a result, accurately modelling modifications to an existing flotation circuit are challenging, particularly when using empirically-derived models from a different operating configuration. Despite these complexities, a recent publication by the authors (Huang et al, 2022) has shown that flotation rates can be accurately predicted from a first-principles model that incorporates hydrodynamic parameters (eg pulp density, superficial gas velocity, feed flow rates etc), surface chemistry parameters (eg contact angle, zeta potentials and surface tension), and size-by-class liberation data. Circuit simulations using this model were shown to be effective in predicting experimental graderecovery curves from the size-by-class mineral liberation matrix. Since the model is derived from fundamental characteristics of the flotation system, it can be used to simulate alternative circuit configurations with varying degrees of recycle. Conventional flotation circuits are operated in a closed-circuit configuration by routing the cleaner scavenger tails (CST) back to the rougher feed to provide an additional opportunity to recover the slow-floating particles. This widely-used flotation strategy has been under constant debate, and several researchers have provided evidence that open circuit configurations provide higher separation and better circuit control (Konigsman, 1985; Bulatovic et al, 1998; Thompson, 2016). Recently, Finch and Tan (2021), used linear circuit analysis to show that open circuit configurations have a fundamental advantage when stage recoveries are high. Given the limitations of these prior studies, the objective of the current work is to further evaluate the merits of the open circuit configuration through a detailed circuit analysis and simulation study incorporating the first principles model described above.

Aug 24, 2022

A Modelling Approach Using a Back-Calculated Induction Time to Predict Recoveries in Flotation

Sep 13, 2010

By Sivell W

We discuss the origin of the Patuki ophiolite complex and the Dun Mountain ultramafics of Middle Permian age in Nelson, New Zealand. It is shown that the Patuki volcanics have strong affinities with tholeiites of mid ocean spreading ridges transitional to alkaline basalts similar to those from fracture zones and ocean islands. At D'Urville Island, typically pillowed alkaline basalts enriched in rare light rare earth elements (LREE) - ophitic spilites - are associated with LREE-depleted (N-MORB-like) tholeiitic spilites with intergranular textures. The metabasalts are associated with a wide variety of sediments, and with sediments are intruded by conformable sheets of serpentinite. Coarsely crystalline mafic and plagiogranitic rocks signify vents and magma chambers, and we propose that the group developed as ocean crust from a slowly spreading mid-ocean ridge, transform association, overwhelmed at intervals by volcaniclastic sediment. Detailed mapping at a scale of 1:5000, and stratigraphic and geochemical development and structural coherence, show that the group is not melange in the Franciscan sense. The Dun Mountain Group, of serpentinites, peridotites, dunites, gabbros and other rocks, intruded the upper Patuki Group as a linear series of aligned pods and sheets. They carried up with them tectonic inclusions of older rock, which were metasomatised, and altered wall-rock, and one low angle dike passed several hundred metres into overl~ing sediment, at moderate temperatures (500 C). The rocks did not act as a floor (and alleged source) for the Patuki, but partly post-dated and were emplaced into Patuki.

Jan 1, 1987

By N Yarahmadi

Characterization of pore pressure is critical for appropriate design of tailings dams. Furthermore, if seepage rates through tailing embankments increase unexpectedly or become uncontrolled, undesirable conditions may prevail to progress piping or internal erosion that could lead to the dam’s instability or ultimate failure. A three-dimensional seepage analysis was performed on a tailings dam using finite element method to find the rate of seepage and pore water conditions in the embankment and foundation. The results were then compared to a conventional two-dimensional seepage analysis carried out on the typical cross section of the embankment and the field data acquired from the instrumentation system. Considering the monitoring data, comparison of seepage analyses results for the two and threedimensional models, showed that the results of the conventional two-dimensional seepage analysis are significantly underestimating reality. Relying on two-dimensional seepage analyses might result in underestimation of seepage rates and impact the safe operation of tailings dams. Similarly, unrealistic prediction of pore water pressure conditions, based on simplified seepage analyses, can lead to overestimation of the rate of strength gain of material and consequently safe embankment raising rates.

Jul 1, 2021

The metallurgical testwork program is generally the most important critical path item for the completion of a bankable feasibility study and hence can become the critical parameter for financing of potential mining projects. This paper presents generic detailed testwork programs suitable for bankable feasibility studies for a gold leaching and polymetallic flotation study. The design of the metallurgical testwork program for each of the two differing processes is discussed and the critical factors that effect the selection of the testwork programs are highlighted. The importance of the metallurgical testwork results in predicting the metal recoveries and cash flow prediction for the project is presented. The detail of the testwork programs costing is broken into activity based methods based on the laboratory and management hours/costs, such that generic rule of thumb costing guidelines can be generated. The scheduling, costing and importance of the metallurgical testwork program to process feasibility studies are discussed in this paper.

Jan 1, 2000

By Shinnosuke U, Zhang HE, Qian X

In this paper it is recommended that pyrite is to be separated as froth from arsenopyrite by selective depression of arsenopyrite in strong alkaline medium (1), by oxidation with chlorinated lime (II), by co-use of chlorinated lime with sodium carbonate (III), and by modification with `L' reagent (know-how) without filtering to get rid of residual copper ions after Cu activation (IV). The corresponding principles of these (new) effective methods were briefly discussed. The artificial mixture (1:1) of pyrite and arsenopyrite could be successfully separated, and concentrates of pyrite containing 2.12 per cent (I), 7.00 per cent (II), 2.60 per cent (III) and 3.16 per cent (IV) arsenic with recovery of 90.9 per cent (1), 89.5 per cent (II), 89.0 per cent (III) and 81.4 per cent (IV) respectively can be obtained by only one flotation. Some effective precautions were suggested to improve the separation of arsenopyrite and pyrite (or other sulphides) by flotation.

Jan 1, 1993