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By Delahey G, Dunne R

At New Celebration Gold Mine the advent of treating primary sulphide ores resulted in decreased gold recoveries of four to ten per cent. The grind coarsened due to an increase in ore hardness and gold in the residue was found to be associated with pyrite. Finer grinding improved recoveries but was impractical as production rates would have decreased to unacceptable levels. An alternative approach that has proved to be viable combines both gravity separation, to recover the coarse gold bearing sulphides, and then regrinding the concentrate in a tower mill prior to releaching in the cyanide leach circuit. The tailings treatment plant was commissioned in December 1990 and details of the first 18 months' operations are Provided.

Jan 1, 1993

By La Brooy S R, Fenton K

A low grade copper flotation tailing from Telfer containing 1.2% Cu as chalcocite and cuprite and 5 gt-t Au was leached with ammonia, cyanide and ammonia-cyanide mixtures to extract copper and/or gold. Direct cyanidation extracted both copper and gold but consumed about 30 kgt 1 NaCN. Pre-leaching the tailing with an aerated ammonia solution containing 28 kgt 1NH3 and 17 kgtl(NHa)2S0a at pH 10 readily extracted up to 95% Cu in about 6 hours under optimum conditions. However pH and total ammonia concentration were critical factors. Subsequent cyanidation ex- tracted 80% Au using 6 kgt NNaCN. Ammonia-cyanide mixtures werefound to selectively leach gold over copper depending on the concentration and relative proportion of NH3 and CN. The best composition for leaching up to 80% Au from Teller tailing was 1.6 kgt t NaCN and 1.1 kgf 1 NH3 in the presence of 0.3 kgt t Cue+. Such a mixture left only 50 mgL-1Cu in the final solution after precipitation of some of the initially dissolved copper.

Jan 1, 1991

The late 1960's and 1970's saw the initial development of the coal resources of the Bowen Basin of Queensland. The projects developed relied on large scale, open-cut operations using draglines for overburden removal and, in the majority of cases, project viability could be established based solely on those open-cut operations. Many of the mines developed in the 1980's have the same characteristics.Unlike these mines, the German Creek Mine has limited open-cut reserves at low overburden to coal ratios, and planning of the complex involved a large open-cut mine capable of developing early cash flow, with phased introduction of underground mining to replace open-cut capacity as the strip ratio increased.

Jan 1, 1985

In 1972, metallurgical testwork on Renison ore indicated a significant proportion of low specific gravity, tin-barren material ideally suited to heavy medium separation (HMS). Further technical and financial studies provided adequate economic justification and in December 1974 the Renison HMS plant was cannissioned. Initial operations were interrupted by the imposition of tin production quotas for three months in 1976; they were also beset with difficulties particularly with regard to mechanical wear. During the first two operating years much develognent work was carried out including installation of a pyrrhotite flotation bank in the medium recovery circuit, investigations into various wear-resistant materials and the use of atanised rather than milled ferro-silicon. By 1977/78 financial year satisfactory performance had been achieved and since then the average floats rejection has been 18.8% of the total ore treated with an associated tin loss of 2.96%. Developnent has nevertheless continued during the last three years, principal modifications being the installation of larger aperture desliming screens and improvements to the overdense cyclone circuit.

Jan 1, 1978

By Hocking G

For some underground structures, the use of the plane strain assumption in stress analyses may not be justified. The finite element method and photoelasticity have been used to obtain complete 3-D solutions, but, for various reasons, neither method has found universal use. The boundary integral equation method (B.I.E.M.) can be more efficient and economical than the finite element method for 3-D problems involving large volume to surface area ratios. A B.I.E.M. program developed for calculating stresses and deformations in infinite elastic media has been used to determine the 3-D distributions of stress around T- and Y- junctions of circular tunnels in stress fields in which the ratios of horizontal to vertical stress are 0, 0.33, 1.0 and 2.0. For the T- junction considered,stress concentrations at the intersection are approximately twice the plane strain values. Except where horizontal field stresses are high, the stresses in both tunnels approximate the plane strain values at about two tunnel diameters from the point of intersection of the tunnel centre lines. The stresses in the two branches reach those for the corresponding plane strain, two parallel tunnel case two diameters from the point of intersection of thq inner tunnel walls. Very high stress concentra- tions occur in the pillar of rock between the inner tunnel walls near the point of intersection.

Jan 1, 1976

By Zhansen P

This paper describes the test re- sults which give a complete proccess of failure of concrete lining embedded in sand medium under load, including the order of appearance of crack along the lining up to failure. nor each crack appearance corresponding calculation being made to assess the redistribution of moment and thrust force in critical section including crown section, section making 45¦ with the vertical etc. De- flection at the above stated critical sections are also measured at each stage of loading. The pressure along the top hori- zontal surface of embedded lining and the vertical sides are measured by pres -sure gauges embedded in sand medium. fhe test results show a complete figure of rupture characteristics of concrete lining embedded in soft ground which approximates alluvial deposite often occur in metro construction at cities near the river side. These test results have been taken as a reference in assessing the action behavior of concrete lining in certain cities in China.

Jan 1, 1987

A failure of the Pit IA highwall in July 1989 led Newcrest Mining Ltd's Telfer Gold Mine to commence underground operations approximately 12 months ahead of schedule. The failure presented four major challenges to management: 1. how to maximise the recovery of the Middle Vale Reef (MVR) in the open pit: 2. how to minimise the risk to personnel involved in the extraction of the remaining open pit ore; 3. how to avoid disruption to ore supply: and 4. how to maintain a permanent and safe means of accessing the underground operations from the base of the pit. The risks associated with meeting these challenges were minimised through the installation of a complex network of real time slope monitoring equipment. These monitors were connected to an alarm system which was combined with detailed operational procedures to be carried out in the event of a highwall alarm being triggered. The accuracy with which the risk of failure has been managed was demonstrated recently when the onset of a second failure was initially identified some 13 months prior to its ultimate collapse in October 1992. The location, timing and size of the failure was able to be predicted allowing appropriate precautionary measures to be taken to ensure safety of access to the underground portal and pumping equipment in the base of the pit. This paper reviews the sequence of events leading to both the July 1989 and October 1992 failures of the Pit 1A highwall and the monitoring equipment and procedures used to identify, quantify and manage the risk to personnel operating in the base of the pit.

Jan 1, 1994

By Beck RW, Booth GW

Differences in the gold contents of sub-sample duplicates, derived from a single bulk sample are a function of analytical and random error, inhomogeneity within the bulk and natural variations in the distribution of particluate gold. By minimising bulk sample inhomogeneity and determining analytical precision, the residual natural variation may be modelled statistically to give an estimate of Bold particle sizes.

Jan 1, 1989

Hydraulic transport of coal has been used for many years on the West Coast of New Zealand to extract small blocks of steeply dipping coal. Recent development at Strongman 2 Mine has seen the use of high pressure monitors to cut coal and a corresponding increase in the scale of production.This paper provides a brief introduction to hydraulic mining, describes the present system used at Strongman 2 and discusses future potential development.

Jan 1, 1998

The relevant characteristic of the evolution of the Pacific continental margin of South America during the Mesozoic-Early Cenozoic has been tectonic segmentation. This has controlled suc-cesive episodes of sedimentary accumula-tion, extrusive and intrusive magmatism and deformation that ocurred at conver-vergent plate edges. During this inter-val, at least three main transverse boundaries played an important role conditioning the existence of paleo-segments of different longitudinal extent at various Periods. These probably correspond to deep-seated faults in the Huancabamba Deflection and at the Arica-Santa Cruz Line; the third boundary projects westward to the Chile Ridge. Tectonic activity appears to have been continous at the Huancabamba Deflection at least since the Triassic. The Arica-Santa Cruz Line was probably an active boundary during the Triassic and Cretaceous; the southernmost boundary may have started to be active at the end of the Jurassic. This tectonic activity has determined the subsidence - uplift and paleogeographic conditions of the paleosegments.

Jan 1, 1990

On Monday, October 25th, 1971 at approximately 12.15 a.m. the night shift proceeding underground discovered smoke at No.1 and No-3 cut throughs on the eastern side of the belt heading and in close proximity to the upcast shaft. Attempts to control the fire continued throughout the morning; as the position underground altered various procedures were adopted in an effort to contain and control the fire. Despite these efforts at approx. 12.40 p.m. a sudden change occurred which made it necessary to withdraw all workmen from underground, the vicinity of the Tunnel entrances and upcast shaft. Sealing of the mine at the entrances was the only remaining alternative. Several boreholes were put down to enable sampling of the atmosphere and air temperatures to be taken. This was essential as a guide to determining when conditions were suitable to allow exploration of the area using mine rescue self contained breathing apparatus.

Jan 1, 1972

By Singh RN

Monolithic packing systems have gained in popularity as a gate side packing method. However, there has been no detailed investigation to assess their underground strength behaviour. This work includes the laboratory and in situ investigation for strength behaviour determined on various monolithic packing materials namely Tekpak-XX, Hydropak-20, Hydropak-30, Astrapak-3R, Flashpak, Thyssen pack and Aquablends. A simple technique for assessing the pack strength was developed at the laboratory by using a penetrometer, of which penetration resistance can be directly correlated with the uniaxial strength of the pack. The in situ strength investigations were made on core samples obtained from three pipes inserted inside the pack, while the penetration test were made on the pack surface. The in situ results indicated that the packing material develops an inconsistent strength on various part of the pack which was mainly related to an inadequate mixing of grouts inside the pack.

Jan 1, 1992

By Boyd G

This paper describes the planning, analysis, design and operational experience of highwall mining based on auger drilling techniques applied to thick coal seams exposed in an opencut highwall. Being the first time such technology has been used in Australia, a large commitment to technical design and logistics planning was given by Callide Coalfields Pty Ltd. This commitment included technical and operations management and supervision, mine services, and the retention of consultants to undertake geotechnical analysis, instrument preparation and instrument installation.

Jan 1, 1991

By Boyd D. M

Minor magnetic anomalies which may be un represented on a magnetic contour map can be extracted from the original survey data and plotted by the described method to provide a rapid interpretation of the magnetic survey, provided that the data has been recorded digi- tally on magnetic tape. The example used comes from 40 kilometers south of Charters Towers, Queensland.

Jan 1, 1977

This paper examines the impact of the time value of money on the location of mining facilities, as examplified by a central processing plant serving several mines. Three approaches, the Euclidean-Distance Approach, the Gravity Centre Approach, and the Rectilinear-Distance Approach, commonly applied to a single facility location problem were employed in the study. The objective function in all three models was the updated value of the following three costs influenced by the processing plant location and defined within the framework of the continuous model of value representation and the continuous interest rate convention: I. the costs of transporting the useful mineral from the mines to the plant, 2. the costs of constructing the transportation links between the mines and the plant, and 3. the costs of maintaining these links over time. Results of the study show a substantial impact of the time value of money on both the processing plant optimal location and the opportunity cost of neglecting the time value of money in the locational considerations.

Jan 1, 1995

By Knasmillner

During blasting body wave interaction with geometrical surfaces induces Rayleigh-waves which propagate along free surfaces, e.g. crack faces or delaminated rock layers. These Rayleigh-waves carry most of their energy within a very shallow surface layer and propagate with very little attenuation in real rock materials. Upon interaction with a crack front a very strong mixed mode stress intensity factor may result and lead to fracture initiation. On the basis of experimental photomechanical results the history of dynamic stress intensity factors Kt and K2 will be studied in Detail.

Jan 1, 1990

Formed in 1965 to investigate the bauxite deposits on the Gove Peninsula, in the Northern Territory of Australia, Nabalco Pty. Limited undertook to determine the feasibility of establishing a mining operation and alumina plant of at least 500 000 tonne/year capacity. The drilling programme undertaken and the analytical methods, assumptions and criteria used to define practicably extractable bauxite are described. The ore characteristics and the interpretation of results used to evaluate the reserves are detailed. The operating techniques developed in mining ten per cent of the reserves and variations experienced between indicated and actual mining are examined and discussed.

Jan 1, 1979

Problems associated with gas management become more significant as exploitation of coal reserves in the Bowen Basin in Australia becomes deeper. At Oaky North mine, relocation of production from one area of the mine to another with a higher gas content required the use of pre-drainage, post drainage and inertisation techniques to enable production activities to continue largely uninterrupted. Innovative surface to inseam drilling techniques were developed for pre-drainage of reserves close to mine workings and have proven to be largely successful. The gas management techniques adopted and specific experience gained are discussed in this paper.

Jan 1, 2005

By Campbell Brown G A

IN 1904-5 diamond drilling operations in the Mount Morgan mine proved the presence of some millions of tons of rich copper-gold ore, averaging about 45%to 50%silica and 22%Fe as sulphide. To smelt this ore in blast furnaces, without previous concentration, large quantities of basic flux were required. Unlimited quantities of cheap limestone were available at Marmor, on the GladstoneRockhampton railway, 50 miles from Mount Morgan, but the supply of iron flux was a more difficult problem. Smelting Operations started with one furnace in January, 1906, using as flux low-grade sulphide ore from the mine, containing very little silica. When the second furnace was blown in this was supplemented by ironstone from small deposits in the immediate district. It was recognized that these sources of supply would be insufficient to keep the full plant going after the third furnace had been blown in. Accordingly, the deposits at Kabra and Mount Etna were opened, neither of which proved capable of supplying the quantity required-viz., 1000 tons per week. Negotiations were meanwhile being conducted with the Marble Island Iron and Limestone Co. to obtain the right to mine at Iron Island, where a sufficiently large deposit was known to exist. Shipments from this source commenced in January, 1907, and ceased at the end of July of this year, when the metallic flux from...

Jan 1, 1911

By Liu Y, Campbell K. R

The paper shows how breakage parameters may he extracted from laboratory batch grinding results and how they may used with reference full-scale hall mill circuit data to estimate the likely size distributions of values and gangue in a full-sca

Jan 1, 1997