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By A G. Greenwood

Research into cemented rock fill at Mount Isa Mines Limited since 1992 is described. The key mechanisms controlling segregation during stope filling with cemented rock fill are described and include the gravity flow mechanism which is described in detail. Examples are provided to demonstrate these mechanisms. Comparisons are made between Mount Isa MinesÆ cemented rock fill and slurry-based cemented rock fills. Recent backfill stability modelling using a three-dimensional finite element program is described.

Jan 1, 1998

By Mistra M, Hu JS, Wadsworth ME

The fluorite/oleate system has been studied extensively since the begin- nings of flotation research. The well-defined relatively simple crystal structure of fluorite and its ionic bonding make it a model system for study. Our understanding of fluorite/ oleate flotation chemistry continues to grow but as yet remains incomplete. Besides a review of our understanding of this system, recent findings are presented in this paper, and new research horizons are identified.

Jan 1, 1984

The emergence of a new range of database communication standards and software has provided the impetus for the development of a new approach to exploration and mining data management. The acQuire software produced by acQuire Software Pty

Jan 1, 1998

By Alford R. A

The causes of the loss of heavy mineral from mineral sands wet concentrators were identified through detailed surveys of two such concentrators. It was found that tray and spiral sluices preferentially lost elongated panicles, but panicle size had little effect on loss. Recovery was shown to increase with panicle density. The major influences on the recovery efficiency of individual concentrating devices (stans) were feed rate and feed grade, recovery increasing with decreased feed rate and with increased grade. Uneven distribution of total solids and heavy mineral to individual stans contributed to losses through the corresponding effects in feed tonnage and grade. Computer simulation demonstrated that significant recovery improvements could be obtained by appropriate adjustment of splitters to optimise the characteristics of internal plant flows.

Jan 1, 1991

In North-West Nelson the Riwaka Complex, a linear basic intrusive complex, is exposed for approximately 45 kilometres. Some 500 kilometres south, across the Alpine Fault, a linear zone of similar but less well known basic intrusives that may be correlatives of the Riwaka Complex is exposed discontinuously for about 80 kilometres. The Complex was emplaced at several centers along a major tensional fracture zone that developed in upper Carboniferous to Lower Permian time. This fracture zone probably formed in response to the development of a west dipping subduction zone that gave rise to the Permian volcanic arcs in east Nelson and western Southland. The Riwaka Complex contains three rock suites. The Fractionation Suite, characterized by cyclic mineral layering and small scale cumulus banding is the largest and is divided into the Ultramafic, Hornblende and Plagioclase Series, each of which is subdivided into several units. The Cumulus Gabbros represent a restricted but important suite of unusual composition, while the third suite is the late phase Diorite Suite.

Jan 1, 1980

The Escondida Porphyry Copper Deposit, located in Chile's II Region 160 Km to the southeast of the city of Antofagasta, is currently owned by Minera Escondida Limitada, a company comprising The Broken Hill Proprietary (57.5%), Rio Tinto Zinc (30%) a group of Japanese companies represented by Mitsubishi Corporation (10%), and the International Financing Corporation of the World Bank (2.5%) (Fig.l)By 1983, most of the reconnaissance drilling was completed and prefeasibility studies were regularly updated as new drilling results were reported and project concepts re-evaluated (Fig.2). In October 1982 the project was transferred from Exploration Management to Operations. By the end of 1984 project pre-development activities, including inpit development drilling, geological exploration, water resource definition, an underground bulk sampling program and the initial project feasibility report, were completed.

Jan 1, 1990

Most orebodies have one or more boundaries which are gradational, where the decision to stop mining is based on an economic cut-off. To maximise profit, this cut-off grade must be chosen correctly. It is necessary to review cut-off grades regularly, as the optimum cut-off grade changes with time, and major changes are hard to implement in a working mine without disruption to production schedules.Whenever a cut-off grade is used, there will be errors in its application caused by errors in the estimation of block grade. These can be minimised by stringent quality control in sampling and by the use of kriging, which attempts to minimise the absolute errors in grade estimation. The kriging method used should produce the most accurate estimates of marginal grade blocks - this will not necessarily be the technique that gives the best overall prediction of head grades.

Jan 1, 1993

According to our experimental results, the following oxygen probe recommended, that is, the magnesia stabilized zirconia was employed as a solid electrolyte and Fe.FexO solid elect- rode was used as a reference electrode. Using such an oxygen probe, we tried to measure the oxygen potentials in molten metals, mattes and gases in the following fields of non-ferrous metal industry, molten copper in the side launder before casting, molten crude lead in the forehearth of ISP blast furnace, molten copper mattes in the forehearth of blast furnace and in the settler of flash smelting furnace, gas in the settler of copper flash smelting furnace and flue gas in the electric furnace for ferro-silicon. In the past ten years or so, many experi- mental results in the field of fundamental studies have confirmed that the equilibrium oxygen potential could be measured conveniently and accurately by an electrochemical method using a zirconia solid electrolyte. Recently, such an electrochemical technique has been also applied to a device for physicochemical invest- igation or process control in the non-ferrous metal industry. Such a device consists of an oxygen con- centration cell with stabilized zirconia, and it is commonly called an "oxygen probe" or "oxygen sensor".

Jan 1, 1980

Current models for the origin of banded iron-formation (BIF) derived in situ iron ore deposits assume that the typical chert and iron oxide banded BIF is the primary rock from which enriched iron ore deposits arise by the selective leaching of quartz and the residual accumulation of the iron oxides. Weathering extends to the base of all the hematite deposits of the Hamersley Province, which lie within the saprolitic weathering zone, as shown by the preservation of the primary textures, and are overlain by a hydrated goethite zone representing the solum. Since groundwater typically contains dissolved silica, derived from the hydrolysis of silicate minerals, greatly in excess of the saturation solubility of quartz, it is incapable of removing quartz from below the watertable, and quartz is preserved in all saprolites derived from quartz bearing rocks. Quartz may be dissolved in the solum due to the influx of meteoric water having little or no dissolved silica, but soil-forming processes that dissolve quartz likewise alter the oxides by hydration and transposition with consequent destruction of primary textures, and there is no suggestion of soil-forming processes having produced the deposits, which typically extend to considerable depths below the water-table. A characteristic feature of the typical hematite orebodies is the unaltered nature of the iron oxides in the ore compared to those in the adjacent cherty BIF. Although the solubility of ferric iron at >10 ppb is much less than quartz, any process capable of dissolving the huge volume of quartz must also affect the iron oxides, but evidence of this is completely lacking in most ore deposits. Hydrothermal alteration at Koolyanobbing in the Southern Cross Province affects both cherty BIF and ore, and clearly shows equal mobilisation and recrystallisation of hematite within quartz/hematite veins and in the surrounding cherty BIF, which shows no evidence for the selective leaching of quartz. Similarly, any metamorphic process capable of removing all quartz from BIF would leave characteristic evidence in the remaining oxides. However, a hydrothermal process may account for at least portions of certain ore deposits, in which the chert bands have been replaced by carbonates at comparatively low temperatures, to produce a quartz-free magnetite/ carbonate rock that is readily upgraded to high-grade ore by supergene dissolution of the carbonates. This process is interpreted to have formed high grade ore at Mt Gibson, Koolyanobbing æAÆ Deposit and Mt Tom Price North Deposit. In addition to carbonate replaced cherty BIF at Mt Gibson in the Murchison Province, there are extensive sequences of magnetite BIF without chert bands, and this chert-free facies of BIF is interpreted as the precursor to the majority of in situ hematite ore deposits, through oxidation and weathering of magnetite and iron silicate and carbonate minerals. The world-class martite/microplaty-hematite deposits of the Hamersley Province are a special case of BIF-derived iron ore deposits that were initiated during the Proterozoic era. Evidence from overlying Wyloo Group conglomeratic horizons containing clasts of Hamersley Group BIF indicates that microplaty-hematite formed within the clasts before deposition, and that Proterozoic subaerial oxidation and weathering of uplifted Hamersley Group formations produced the microplaty-hematite in both chert-free and cherty BIF.

Jan 1, 2002

By R Lau

In recently completed road tunnel projects in Queensland, such as the Airport Link and the Clem7 tunnels, there is a smoke duct running along the roof of the carriageways to extract smoke in case of fire. In New South Wales, no road tunnels have a smoke duct. In the Melbourne City Link tunnels, there is a small smoke duct running along the roof. All of the tunnels are safe as claimed by the designers and authorities. However, there is significant cost associated with providing a full size smoke duct compared with no smoke duct. This paper is going to present a comparison of the road tunnel safety with a smoke duct and those without one from a risk perspective. It further discusses the cost-effectiveness of such provisions and whether similar levels of safety could be achieved without a smoke duct.CITATION:Lau, R, 2014. Smoke duct or no smoke duct for road tunnels, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 83–86 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By Schneider CL

The calculation of the liberation spectrum in the product from continuous milling operations is a problem of considerable importance, and it is difficult to solve because the population balance equation must be integrated in two-dimensional space. Complete solutions require a very detailed knowledge of the complex interactions between the fracture patterns and the mineralogical ore texture when brittle particles are subject to impact fracture. Most of the liberation models that have been developed to date apply only to batch comminution processes and under these conditions the liberation problem can be studied in isolation. When the comminution is continuous and forms a unit operation in a flowsheet that includes classification and separation operations, the situation is very different, and then the liberation of the minerals must be described when single particles of known mineralogical composition are fractured. Important industrial examples are conventional milling circuits closed by hydrocyclone and regrind mills in flotation plants. This paper presents an efficient computational algorithm for the calculation of the liberation spectrum produced by continuous milling operations. The algorithm relies heavily on the detailed internal structure of the Andrews-Mika diagram. The modifications that are required to make this diagram apply to practical ore minerals, and the internal structure of this diagram can be established using single-particle fracture on mono-size, mono-grade material but suitable liberation models are essential to interpret the data in terms of the cross transfer coefficients required for the population balance procedure. Models proposed by Leroux (1992) and King (1990) are compared to experimental data.

Jan 1, 1993

By R J. Butcher

Many deposits have been evaluated as potential block caves over the last 20 years due to the perceived benefit of low operating costs. However, block cave projects are typically capital intensive, with mass mining providing high throughput rates that required large investments in mining, processing and utilities infrastructure. While the key economic metrics in deciding to proceed with a caving project are typically net present value (NPV) or internal rate of return, these may not represent the best decision metrics for some companies. Where a caving project is competing for scarce capital amongst other projects in a company’s portfolio or where the caving project is the only project being evaluated by a company trying to raise capital, other metrics may be more appropriate. This paper explores the use of present value ratio and the minimising of maximum negative cash flow as suitable metrics in determining alternative strategies. Trade-offs between optimising for economic value and capital efficiency measures allow for decision-makers to evaluate potentially higher-risk, higher-capital and maximum NPV projects against lower-risk, lower-capital projects.CITATION:Stewart, C A and Butcher, R J, 2016. Block cave evaluation, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 809–816 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Woodcock J. T, Rummel P. H, Sparrow G. J, MacRae C. M

An automated method, which is believed to be the fastest in the world and which can be used by mineralogically-untrained technical assistants, has been developed for the rapid location of native gold particles and other gold minerals down to 1 pm in size in ores, concentrates, and tailings using a scanning electron microscope. Searching of a 25 mm diameter polished block in 1 pm steps usually requires 3-4 h. Examples of the location of native gold and gold tellurides in drill core sections, in crushed ore samples and gravity and flotation concentrates, and in various metallurgical test products are given. The results have application in ore exploration, in guiding metallurgical test programmes, and in assessing metallurgical per- formance in testwork and in operating plants.

Jan 1, 1991

By Dance A

Highland Valley Copper recently implemented a system of measuring run-of-mine (ROM) ore properties and monitoring their effect on both mine and mill performance. These properties are principally ore hardness and size. For some years, Highland

Jan 1, 1998

The results of a systematic geochemical survey of rare elements are applied to elucidate genetic relations in a suite of rocks and to predict the probability of mineralization. The geology, radioactivity, major element geochemistry and classification of the main intrusives are described. The distribution of a group of rare elements, their concentration trends and the bearing these have on the emplacement sequence of the rocks are considered in some detail. The guides for exploration in the Pilanesberg that emerge are listed and some areas which substantiate predictions are described briefly. It is concluded that a study of rare element trends can make a considerable contribution as an exploration tool and for clarifying relations between the members of rock suites.

Jan 1, 1986

By Kikuta K

ISP (Imperial Smelting Process) produces zinc and lead simultaneously from zinc and lead sulphide concentrates and recovers copper and precious metals into a lead bullion. The strength of sinter is important to keep permeability in the shaft of the Imperial Smleting Furnace. The residual sulphur content of the sinter is also important as it causes metal losses into slag. The paper describes an investigation into the sintering operations to improve sulphur elimination and sinter strength. The micro structure of the sinter and the effect of the blast rate, sintering temperature etc have been studied.

Jan 1, 1993

By Fourney W. L, Dick R. D

A small-charge rapid excavation system employing a novel penetrating cone fracture initiation and propagation technique has been demonstrated to be capable of excavating the hardest of rocks at efficiencies (energy per unit volume of rock removed) four to ten times greater than attainable with conventional drill and blast. Significant enhancements to the concept developed during the research efforts include the use of propellant rather than explosive charges and a device for containing the charges and effectively sealing the shot-holes. The experimental results, including the excavation of several tons of hard rock in a research mine, have confirmed the novel breakage process and provided a data base for the design of a continuous hard rock mining machine based upon the concept. The small-charge excavation system would be attractive for civil construc-tion operations where sensitive structures, equipment and personnel would be in close proximity to the excavation face. The system would be attractive for selective mining operations where the ore rock could be fragment-ed and processed separately from the barren country rock. The barren rock could then be backfilled underground and eliminated from the traditional hauling and milling operations.

Jan 1, 1990

The quality of the rock mass in which an excavation is being driven has a strong influence on the level of dynamic forces to which the excavation can be subjected and sustain damage. Though each specific rock mass occurrence is unique yet there are common rock mass features which influence the outcome of controlled blasting in a similar way. A field study was conducted which involved assessment of blast damage at several operating mines and the blasting of small-scale models. The effects of block size and strength, joint parameters, ground water, weathering of rocks and rock mass rating on the results of controlled blasting have been investigated and discussed in this study.

Jan 1, 2003

The design and selection of components for belt conveyors is a well known procedure and many handbooks, catalogues and design manuals offer a wide range of detailed information which can be applied to most of the known conveyor problems. The aim of this paper, however, is to investigate the various methods of conveyor drive configurations, and incorporate the latest technical achievements in the control systems, particularly for high capacity conveyor systems carrying ore from pit to processing plants where the lowest maintenance, operating and initial costs are of major importance. Past experience has proven that multi pulley drives can reduce initial capital cost of a conveyor; this leads to the need for better torque control during startup, running, stopping and load sharing. Many methods of torque control are available and have been used in the past. All types have their advantages and disadvantages and must be considered when designing a conveyor or conveyor system. However the recently developed solid state electronic soft start controls utilising AC squirrel cage induction motors are gaining acceptance, especially for a conveyor system where the same control and logic system can be used to transmit startup commands to more than one

Jan 1, 1978

The South Comet mine is an underground silver-lead-zinc mine located on the West Coast of Tasmania with an annual production in the order of 35 000 tonne per year. All ore mined is shipped to the Rosebery mill by road, a distance of 17 km.

Jan 1, 1993