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Estimation of the semi-variogram is basic to the geostatistical processing of data. The most widely used arithmetic average estimator is here employed with various sampling patterns to calculate experimental semi-variograms in a deposit which is simulated to have a defined semi-variogram. Percentage differences between theoretical and experimental semi-variograms are reported.

Jan 1, 1984

By de Brodtkorb MK

Late Cenozoic ore deposits "Precious and base metal-rich" and " Sn-Ag-polymetallic"of Northern Puna are associated either with Middle Miocene dacitic volcanic-dome complexes or with Upper Miocene dacitic-andesitic volcanic centers. Ore mineralogies and their related volcanism are discussed. A strong link is observed between the Cenozoic Metallogenetic Province of Northern Puna and the Southern Bolivia Tin and Polymetallic provinces.

Jan 1, 1995

Managers are demanding efficient use of their resources and part of this demand is leading to the idea of integrated audits for Occupational Health and Safety (OH&S), quality and the environment. It is possible to construct audits which test the compliance in this area with standards established by management systems and it may be that such an integrated audit of a site could reduce the time of auditing and be equally effective as three separate audits. However, this is only a maybe. To do an audit on all three aspects when they are not fully integrated results in more time wastage than doing three separate audits. But organisations are not structured around the audit process (some financial managers may query this statement). The organisational management systems are put in place to achieve the organisational goals - presumably in an efficient and cost-effective manner.

Jan 1, 1995

By Burks WG, Hughes FE, Muceniekas E, Whitcher IG

The area containing the iron field, recognised by the writers, is part of an uplifted, portion of the 'Western Australian Plateau,' ranging in elevation from about 1,000 feet to about 3000 feet above sea level. The local rock succession is flat-lying or moderately-folded and belongs to the Nullagine Series of Upper (2). Precambrian age. This series forms the Hamersley Rangeland vast portions of the...

Jan 1, 1964

By Longworth C. R

This paper descrioes a case history of a coal mine which developed un'tahle roof conditions due to mass sliding of the overburden strata on a claystone band within the coal seam. The sliding is believed to have been initiated by stress relief associated with the removal of overburden alongside the entry portal of the underground workings. Once in motion, the roof block was kept moving by bulking due to roof collapse in the normal underground goafing operations. Control measures in the form of an earth and rockfill buttress against the entry portal and a sequential mining plan to create goaf areas alongside the entry portal have been initiated to attempt to limit movement. The operation has been continually monitored and a gradually decreasing pattern of movement is being re, orded.

Jan 1, 1981

The main objectives of this paper are to identify the main sources of coal dust and to investigate measures for minimisation of dust generated at these sources at the Bukit Asam open cut mine, on the island of Sumatera, Indonesia which uses a

Jan 1, 1994

By Gorken A, Mular M, Stewart A

PT Freeport Indonesia operates one of the largest copper and gold concentrator complexes in the world. Flotation is used to produce a single copper-gold concentrate. In 1995, PT Freeport Indonesia and Cytec Industries Inc established a joint p

Jan 1, 1997

By T Ueda an, T Sasaoka, A Yabuki, H Shimada

The basic concept of auger mining is to extract coal beyond the economic limits of surface mining technology by drilling holes of an appropriate diameter size into the exposed seam of the highwall as deep as is technically, economically and operationally feasible. This method of mining is used at the final highwall of typical surface mining operations. This paper describes the auger mining systems and discusses the methods to increase the coal recovery in auger mining from a field trial in Australia.

Jan 1, 2003

The comparison of belt drives with other types of power transmission involves the consideration of many factors before a final choice is made. Where other forms of power transmission might also be suitable, the selection of the correct type of belt has first to be made, in order to obtain a true comparison. The paper first deals with the types of belting available, followed by a description of most other forms of transmission equipment. An example is then given of the selection of suitable belts, which are then compared with other types of transmission. Comparative costs are also given. Reference charts provided show drives found suitable in general practice...

Jan 1, 1964

Kinetics of bubble-particle interaction, surface hydrophobicity and interfacial phenomena in sulfide mineral flotation are discussed in this paper. Results of the measurements of a bubble and mineral induction time (IT) and detachment force (DF), vacuum of bubble evolution (VE) and mineral floatability are discussed for pyrite, galena, chalcocite and chalcopyrite. Natural wetting and wetting induced by xanthates with different lengths of alkyl chains are examined. Experiments show the existence of several maxima of hydrophobicity on dependences of pH and electrochemical potential. These maxima are attributed as the reflection of mineral surface heterogeneity due to xanthate adsorption and the presence of cationic and anionic centres with uncompensated positive and negative charges. These charges can be neutralised by both regulation pH and applied potential. The aim of this paper is to evaluate a thickness of the rupturing film and to estimate how long the bubble-mineral interactions are according to the experimental values of IT, in order to develop a procedure for comparing of the results of DF and atomic force measurements in the same dimensionality, and to compare the results of the experimental studies on the wettability of sulfides with those predicted by the models of physics of capillarity.

Jan 1, 2005

By Doxford CI, Perry AJ

Mining Lease 908, situated on Gorge Creek near its confluence with the present Cape River system, has been subjected to intensive recent exploration for alluvial gold.The gold is hosted by a buried palaeochannel, the Gorge Creek Lead and by an overlying remnant meander of the Cape River. The principal, if not sole, sources of gold within the Gorge Creek Lead are the northwest trending Great Australian Reef and Green's Specimen Reef systems which are situated on adjacent high ground. Lower grade gold bearing eluvial ground separates the reefs from the Gorge Creek Lead. The sources for gold within the old Cape River system channel (Canton Lead) are thought to be situated some distance upstream, one source perhaps being the Lolworth Diggings located 30 kilometres to the northwest.Exploration of previously "heavily dug" ground on both leads consisted of detailed geological mapping followed by the collection and treatment of bulk samples from eight costeans. The wash samples varied in size from 120 to 396 cubic metres. Treatment was undertaken through a commercial sized conventional wet screen and jig plant.

Jan 1, 1986

By Bebb G

This paper describes the use of SURPAC, a survey/mine planning software package as used at Central Norseman Gold. It details the basic operating principles of the package, the applications in which it is employed, and its time and cost benefits and efficiencies as they apply to the above operations, both surface and underground.

Jan 1, 1985

By D Fargher

BHP BillitonÆs Cannington operation began production in 1997 and is presently the largest tonnage and lowest cost single mine producer of both lead and silver in the world. The original design capacity was 1.5 Mtpa and this has progressively increased via a series of debottlenecking projects in both the mining and milling operations. In 2003, 2.39 Mt of ore was mined, whilst 2.31 Mt of ore was milled. In February 2003 Cannington received approval to expand the project to a sustainable capacity of 2.4 Mtpa. This resulted in underground development into the northern zone, upgrades to the concentrator, increased accommodation at site and power station capacity. The Cannington project development team implemented a partnership approach to the project. Fraser Osborn Engineering and Outokumpu Technology worked closely together with the Cannington team to meet all of the project constraints.

Jan 1, 2004

Throughout 1992 Pasminco conducted field trials of the Mobile Miner MM130 at Broken Hill. The goal was to develop the machine to achieve acceptable reliability and establish production rates.

Jan 1, 1993

The patented "Epytensic" pump of Minnovation Ltd, a multiple piston pump, is used widely on shearer loaders and by partial high pressure watcr jet cutting strategically in relation to cutter picks not only improves cutting rates, but saves power and increases the life of gearboxes and picks, as well as improving dust suppression. The "Face Side Pump", also a piston pump, located on the ranging arm gearhead has advantages over gateroad pumps and shearer body pumps. The "Extraction Drum", hydraulic air mover system, linked with the above innovations and high pressure water, have further advantages in methane and dust removal. Some modifications providing these systems need workshop applications but most are possible underground with minimal changes to shearer profiles and advantages of minimising hosing, along with the other advantages stated.

Jan 1, 1991

Precious metal mineralization at the North Arm goldfield in SE Queensland occurs in the Triassic North Arm Volcanics, a sequence of andesite to rhyolite, pyroclastic and epi- clastic rocks deposited in a continental envir- onment. This unit displays a well-defined fracture system on Landsat imagery, including several arcuate structures which may represent former calderas. Two of the latter are associ- ated with zones of hydrothermal alteration, breccias and anomalous precious and volatile metal values. At the North Arm prospect, alter- ation is zoned from outer propylitic into exten- sive sericitic, although K-feldspar alteration is prevalent in the rhyolite. A zone of advanced argillic alteration is also present at Mt. Ninderry, SSE of North Arm. Alteration involves depletion of Na, Ca and Sr, and vari- able enrichment of S, As, Au, Ag, Hg and Mo. K and Rb are strongly enriched in K-feldspar altered zones. Precious metal mineralization occurs in veins, stockworks and hydrothermal breccia zones, and pervasive low grade Au-Ag dispersion is found throughout the sericitic and K-feldspar altered rocks. Veins and brec- cia interstices contain abundant quartz (common- ly banded), minor pyrite, calcite and sericite, with traces of silver grading to electrum, frei- bergite, naumannite, allargentum, marcasite, chalcopyrite and sphalerite. Mineralogical and geochemical characteristics are consistent with that found at volcanic-hosted epithermal precious metal deposits, particularly with the low-sulphur/adularia-sericite type.

Jan 1, 1987

By White A. H, Vihena M. T M B

Presently, orebody modelling consists basically of fitting a mathematical model to represent spatially a certain geological variable, generally grade. An orebody model is constructed from a set of sample data obtained from various locations in the orebody, thus it is only one form of representation of the true phenomena. Checking the compatibility of the data with the modelling procedure is the most important factor when assessing confidence in the orebody model. The level of confidence in the model will depend on the adequacy of the data set and the validity of the basic assumption required by the modelling method. Fractal geometry is one way of modelling the spatial distribution of a geological variable in an orebody geometry. Fractals can be used to interpolate the Z(x) geological variable at unsampled sites. The concepts of self similarity and self affinity that form the basic assumption of fractal geometry theory which areinvestigated. The population distribution of the geological variable in question must be examined to determine the appropriateness of both fractal geometry and geostatistical modelling methods. The selection of the most appropriate method depends on the available data. A researcher or a practitioner needs to understand the strengths and limitations of the various modelling methods before choosing the most appropriate method. This study investigates the fractal properties of grade distribution using the variogram and some proposed variations as techniques to measure the fractalness. The aim is to assess applicability of fractal geometry theory to modelling ore grade distribution in a deposit. A comparison of the results demonstrates the methods which better capture the spatial behaviour of the variable under study.

Jan 1, 1995

The operators of the iron ore railroads in the Pilbara faced problems of excessive wear between rail and wheels as the tonnage hauled increased in the early 1970's. Joint research projects were begun between Hamersley Iron, Mt Newman Mining and the BHP Melbourne Research Laboratories to study these problems and recommend solutions. The particular problems of wheel rail interaction were solved by asymmetrical profile grinding of the rail and modifications to the machining of the wheels. Rail materials were improved through increasing yield strengths by alloying and by heat treatment. Wheel materials were improved by alloying. The economic benefits of these improvements have been demonstrated by much reduced re-rail requirements and other reduced maintenance costs.

Jan 1, 1986

An examination has been made of the rate and extent of removal of carbon from scrap metal charges when the melt is exposed to atmospheres which are reducing or oxidising with respect to FeO at unit activity. The mechanisms of decarburisation of molten Fe-C-S- P-Mn-Si alloys with H2/CO/H20/C02 gas mixtures with controlled compositions at high or low concentrations of carbon in the melt in the presence and in the absence of sponge iron, in both slag free melts and in the presence of various slag forming additives are discussed. A significant quantity of carbon can be removed from the metal during the melting stage and under optimum conditions, a high percentage of metal recovery and low carbon can be obtained after exposure of melt to the above gas mixture with controlled compositions. The presence of ferrous oxide provided by poorly reduced ore in the charge and the use of controlled atmospheres facilitated the removal of carbon to very low level during the melting period.

Jan 1, 1984

The Beaconsfield gold mine processing plant is a complex operation and utilises crushing, grinding, gravity gold concentration, sulfide flotation, bacterial oxidation, cyanidation and zinc cementation to recover gold from the partially refractory ore. This paper discusses the challenges, developments and advancements throughout the processing plant since start up, which have culminated in a 25 per cent increase in the mill throughput over the nameplate design and a concomitant gold recovery increase from 75 to 92 per cent. The improvements have been attained via advancements in mechanical integrity, metallurgical review, process control and operator training, resulting in the current operation producing over 630 000 ounces of gold to date.

Jan 1, 2007