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By Hengst B

The first production stage in any mining operation is the breaking of whole rock into fragments small enough for loading and subseq- uent handling. This primary fragmentation is most frequently accomplished with blasting. The maximum fragment size and the fragment size distribution have an influence on the subsequent loading, handling and crushing costs. It is assumed that total rock fragmen- tation in practice is a result of an interact- ing array of radial cracks from various blastholes. The representation for the basic pattern of radial cracks emitted from a particular blasthole is first described. A model is then developed simulating the interaction between blastholes at various burdens and spacings, and in simultaneous and delayed modes. The resultant picture is analysed and a fragment size distribution calculated. Methods of incorporating the existing faults in the rock are also discussed. Finally application of this model to various facets of mining are considered.

Jan 1, 1977

By Harris RW

Acoustic Emission structural integrity evaluation tests rely on the validity of the detected acoustic emission data and the ability of the practitioner to both analyse and interpret the data to make a correct decision on the future use of the structure tested. Unfortunately with acoustic emission surveillance testing, it is not possible to know that all the available data has been assessed property. The equipment sensitivity, threshold settings, and event capture capacity, when combined with the decision making ability of the operator in real time, make it very difficult to achieve reliable integrity evaluation. The main problem is to interpret the data and so any monitoring system should involve expert systems in conjunction with both acoustic emission and other operational monitoring data to maximise the utilisation of the large amounts of information now available from operating plants, mines and structures.

Jan 1, 1991

By P D. Williams

The Phoenix mine is one of NewmontÆs open-pit operations located in Nevada. Mining started in 2005, with the mine producing gold, copper and silver. The mine life is about 20 years. The gold grade estimation uses the Newmont in-house indicator kriging approach to handle the high variability in drill hole composite grades and support mining selectivity. Each block contains up to 200 subblocks with different gold grades. A flotation mill is designed to process oxide and sulfide ores, recovering gold, copper, and silver. An additional copper leach process is currently under study to process low gold and high copper oxide material with low copper recovery in the mill. The metallurgical recoveries and processing costs are dependent on many variables including rock formation, metallurgical domain, cyanide soluble copper and sulfide contents. This paper describes the Newmont in-house indicator kriging procedures and the revenue based mine planning software system implemented at Phoenix mine to address the complexity resulting from multi-process, multi-metal and indicator kriging model.

Jan 1, 2007

By M Thomas, S Lambert

The Tugun Bypass Tunnel in Gold Coast, Australia was constructed using diaphragm walls with the top-down cut-and-cover method to allow simultaneous construction of an airport runway extension above the tunnel, whilst excavation of the tunnel continued underneath. The tunnel was built in an environment of high groundwater table and deep deposits of alluvial and estuarine soils with the toes of the walls founded in soil deposits. There was a potential risk for differential settlements to occur between the diaphragm wall panels, caused by the runway fill placed over the tunnel roof during excavation. Dewatering within the diaphragm walls was required to facilitate the construction of the tunnel. The tunnel was also built in an area where environmental considerations were of great importance. Three-dimensional numerical modelling was undertaken to predict the differential settlements of the tunnel with considerations of varying subsurface profile, staged excavation and dewatering, non- uniform surface loading and complex soil-structure interaction. Field instrumentation and monitoring was implemented to confirm numerical predictions.  

Jan 1, 2008

By Mouritz M

Ventilation characteristics and the occurrence of nocturnal surface inversions have been investigated within the Mount Whaleback open cut iron ore mine at Newman in Western Australia. When winds are light and/or nocturnal surface inversions form within the pit, episodes of atmospheric stagnation can occur with resultant accumulation of dust, diesel exhaust fumes, and sulphur dioxide evolved from spontaneous combustion of pyritic shale. Nocturnal surface inversions were recorded outside the mine on more than two-thirds of nights. Inside the pit, inversions were much less frequent - occurring on roughly 20% of nights when they were observed outside - and much weaker - the maximum temperature difference being 5 C¦ over 210 m inside the pit compared with 15 C¦ over 150 m outside.

Jan 1, 1988

By Bhaskara Sarma P V R

Solvent extraction of cobalt from an ammoniacal ammonium sulphate medium was carried out using Di(2-Ethyl Hexyl) phosphoric acid in kerosene as diluent. The effect of ammonium chloride and ammonium sulphate on the extraction efficiency was studied. The extracted species in the ammonium chloride and sulphate systems were CoAz2HA.NH4CI and CoA3.HA.2(NH4)2SO4, respectively. Ammonia scrubbing and cobalt stripping studies were carried out from loaded and ammonia free organic Respectively.

Jan 1, 1992

By Medhurst TP, Trueman R

The aim of the paper was to model numerically some aspects of the extraction of coal pillars by split and fendering. A two-dimensional elasto-plastic plane strain model with strain softening and interface mod- elling was used. The model was able to simulate the improvement of conditions experienced in lifting from the fender, when the roof adjacent to the fender has caved. In contrast, when a stook was left, providing support to a span of uncaved roof, the model pre- dicted the fender would suffer considerably more de- formation and strain.

Jan 1, 1992

By Strickland R. E J

Heap leaching is establishing itself as an efficient method for the extraction of gold from low grade ore. It has the advantage of low capital costs, low operating costs and rapid startup. However, not all ores are amenable to heap leaching. It is only applicable to well oxidized ores that have reasonable permeability characteristics. Ore with excess fines or clay often display low permeability and are unsuitable for heap leaching.In this study, an attempt has been made to increase the rate of cyanide leach solution percolation by flocculating clay particles or reducing the surface tension of the leach solution. A wetting agent was found to decrease the rate of gold dissolution, possibly by presenting a hydrophobic surface to the gold particle. Flocculation of the clay increased the solution flow rate. The flocculation agent had no affect on the total gold leached but decreased the leaching rate.

Jan 1, 1992

The cost-effectiveness of blasts involving radiating blastholes is cur- rently restricted in the following ways. (a) Significant percentages of potential explosion energy are not being liberated; the collar sections of some charges are being dislocated and/or desensitised by the detonations of adjacent earlier-firing charges. (b) If the minimum charge spacing is too small, detonation of an early- firing charge can initiate an adjacent charge sympathetically, thereby eliminating the benefit of any intended inter-charge delay. (c) The overall distribution of energy is poor. Appreciably better fragmentation would be achieved if current drill- ing patterns were to be replaced by staggered fans/rings having a toe spac- ing : burden ratio of about 4 : 1. This wide-spaced pattern would enable a higher percentage of the potential energy to be released, would reduce the incidence of sympathetic detonation and would provide a superior overall distribution of this liberated energy. If improved fragmentation is not required, the proposed fan/ring design should allow a significant expansion of the blasthole pattern with consequential cost savings in drill- ing, explosives and initiation.

Jan 1, 1988

Detailed studies of mineral paragenesis, isotope and trace-element geochemistry, and physical mineralogy at Mount Morgan are compatible with deductions by Geopeko Ltd geologists concerning field relationships in the mine area. Considered together, field and laboratory data suggest that the Mount Morgan deposit originated from a shallow, intrusive, acid volcanic dome similar to those which produced the Kuroko-type deposits in Japan. At Mount Morgan, however, interaction with sea water was much less, the sulphides were concentrated rather than forming a group of deposits, and only the throat of a breccia vent is pre- served, so that only the lowermost parts of Kuroko-type deposits can be compared with the Mount Morgan mine. A final difference lies in the presence at Mount Morgan of a quartz diorite adjacent to the ore. Mineralogical data are compatible with post-ore intrusion, possibly up an earlier volcanic fissure.

Jan 1, 1974

The epizonal Ag-Pb-Zn vein deposit at San Bartolome is characterised by a base-metal sulphide assemblage containing the spectacular development of interpenetrating, bladed networks of pyrrhotite which have been replaced by marcasite and pyrite. A similar assemblage displaying the same crystal habits and textures are also a diagnostic feature of the Sn and Sn- Ag deposits of Bolivia. On this basis, it is reasonable to conclude that both deposits were formed from fluids of similar nature and origin. Although no economic accumulation of Sn is known in San Bartolomr, further comparison of the geologic setting, age, mineralogy, fluid inclusion data and magmatic association of this deposit with the Bolivian systems has highlighted additional similarities consistent with a hypothesis that more extensive Sn mineralisation might exist in the San Bartolomd area.

Jan 1, 1995

By Stuedel J

Starting from comprehensive programme systems for monitoring tasks of any kind, this paper follows the steps of the programme system hierarchy from top to bottom. The monitoring and control centres for entire production units, the subordinate centres, i.e. district control centres, the microcomputer based autonomous control systems, and data input by mobile terminals are discussed. To an increasing extent, the main emphasis is shifted from monitoring and control of individual machinery to optimized operation of extremely complex comprehensive systems. Network displays, for instance displays of production, transport, supply- and evacuation-networks as well as of safety systems, gain increasing importance. Personnel deployment systemsand planning networks as well as stocktaking and accounting are more and more closely linked with the above-mentioned networks. In order to keep development and application (purchasing) costs low, and to assure compatibility, the use of standard modules is to be assigned particular importance. New module developments are introduced, and the design of standard interfaces for computer and module coupling are discussed.For conclusion, a short view is given on the opinion of the line manage-ments on how future hierarchic systems should be featured in terms of individual units and overall systems, and used.

Jan 1, 1985

Recent data contributions to New Zealand Mesozoic terrane geology confirm the consensus interpretation that New Zealand grew by the progressive addition of material by plutonic and accretionary processes along the Gondwana margin. The data also (1) emphasise the discontinuous but inter-related nature of these processes of continental growth, (2) better establish a direct Gondwana correlation of the Western Province and probable Gondwana provenance of at least some of the Eastern Province, (3) suggest specific times and places when passive or strike-slip rather than subduction regimes are recorded along the south Gondwana margin, and (4) potentially lead to interpretations emphasising parautochthonous rather than far- travelled relationships between many New Zealand terranes.

Jan 1, 1995

By Voermans F. M, Hoyle M. W H

The Archean geological sequence in the West Pilbara region (Fig 1), a deformed greenstone volcano-sedimentary succession regionally intruded by layered mafic/ultramafic lopoliths, batholithic granites, granite stocks and transected by swarms of dolerite dykes, has prompted several companies to search for a variety of base metals and and platinoids (Fig 2). In the first instance, detailed aeromagnetic surveying was completed, producing patterns of marked magnetic anomalism which proved substantially successful in the demarcation of areas warranting geological reconnaissance and detailed follow-up. Revelant to this paper were the obvious magnetic features overlying outcropping and buried mafic/ultramafic bodies which ultimately were proven to be host to Ni-Cu sulphides, pgm, Ti, V, Cr and, more recently, Ag and Au mineralisation. Routine stream sediment, soil sampling and ground geophysical techniques of the day appear, in most cases, to have been adequate in the detection of mineralisation, except in the case of Radio Hill massive sulphides where the Turam E.M. (1972) signal essentially failed to detect the blind conductor (Peters, de Angelis 1987).

Jan 1, 1988

On the 17th November, 1964, a new No., 2 lead blast furnace was blown in at Port Pirie. The furnace departed from previous designs by incorporating a centrally located continuous tapper for both lead bullion and slag. The use of a central tapper permitted a simple and effective layout for the handling of both products. Considerable development was necessary to bring the furnace to its present level of efficiency. Units vital to the continu- ous operation were developed to allow quick replacement, thus ensuring high time efficiency under varied operating and maintenance conditions. The furnace was designed with the following objectives in mind, 1. increased crucible life, 2. elimination of oxygen for slag tapping, 3. higher temperature slag for fuming operations-, 4. less operator skill needed, 5. reduced tapping tool consumption, 6. elimination of settler skull and scrap lead, 7. better control of blast air distributi.nn. And

Jan 1, 1975

Interaction between rock and fluid plays a critical role in rock engineering ventures such as stimulation of oil and gas wells, geothermal energy recovery and nuclear waste isolation. Robust and reliable design of the related services and underground facilities is based on understanding of the mechanics and chemistry of the coupled hydromechanical- thermochemical processes. This paper explores the application of the theory of such processes in minerals engineering, with particular reference to rockburst mitigation, in situ solution mining and cavity completion of coal-bed methane production wells.

Jan 1, 1995

The control of industrial grinding circuits in Australian concentrators has been practised for many years in one form or another. Some have established simple feedback loops in areas such as fine ore bin feeders (tonnage control), mill pump sump levels (flow control) and water additions (density control). There are also some sophisticated systems which infer circuit product size using complex measurements of mass flaws and water additions in the circuit and attempts are made to control those flaws to produce a constant circuit product size. The inferred size method in Australian concentrators has become firmly entrenched in the last ten years and control techniques involving the use of direct size measurements with reliable on-stream sizers have been Ignored.

Jan 1, 1983

By T Ross, S Cameron

The requirement to use explosives in ground temperatures exceeding 50¦C is becoming more common as mines work to maximise the recovery of their resources. Orica Explosives was requested to assist in the development and implementation of æhot blastingÆ safe working procedures at Liddell Coal Open Cut in the Hunter Valley. The mine operator, Hunter Valley Earthmoving (HVE), had to contend not only with elevated temperatures in their overburden resulting from burning coal beneath, but also old underground workings which tended to exacerbate the problem. The paper discusses the following issues:the consultative process that was used to develop the procedures employed to ensure the process could be carried out safely; the technical issues surrounding blasting in hot ground, including temperature monitoring, product selection, application and design to ensure safety and performance were maintained; the need for confidence and trust in the team that was working together in a potentially hazardous environment, the emotive issues that were encountered and how they were addressed; the value of a regular review process combined with open and honest communication to ensure the procedures represented best practice and that all stakeholders understood the process; and the value delivered to Liddell Coal when sterilised areas of coal became accessible with little disruption to the mining process. The paper also discusses the challenges that were encountered in the Reservoir Block where proximity to major power lines and rail infrastructure meant that hot blasting procedures had to also consider vibration limits and the need for Energy Australia to disconnect the power.

Jan 1, 2001

By Johnstone RD, Rattenbury MS

RACE Quartz-calcite veins containing Au, As, W, Cu, Pb, Zn and Fe cross-cut Alpine Fault- related structures in the Alpine Schist of South Island, New Zealand. These veins, and some other related veins have been deposited by metamorphic fluids at 250¦C to >320¦C at pressures of a few hundred bars. The fluids were very variable in composition, with 0 to 50 mole % CO2 and 2 to 18 wt. % NaCl equivalent. Penetration of hot metamorphic fluids to shallow levels in the crust was facilitated by rapid uplift of hot rocks at a compressive plate margin. Fluid immiscibility at shallow levels caused concentration of salts and metals into the aqueous phase. Gold precipitation was caused by reduction by pelitic country rock and/nr dluILion by other aqueous fluids.

Jan 1, 1987

By Conochie DS

SIROSMELT is a successful new pyrometallurgi- cal furnace system using a top-entry lance which can be submerged in both slag and matte. The lance is of simple construction, and is cooled by process air. Pilot plant work commenced in the CSIRO Division of Chemical Engineering in 1972 using a 50 kg batch reactor. This paper traces the development of the technology through various slag cleaning and smelting processes up to a scale of 5 tonnes per hour continuous feed. Strong co- operation between CSIRO and the Australian smelting industry has contributed greatly to the success of SIROSMELT.

Jan 1, 1984