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By Bain J. H

Since zinc was first deposited at Risdon in February, 1917, provision of the most economical cathode assembly has been a subject of extensive research, the major problems being corrosion and efficient use of power.From the corrosion viewpoint, a perfect cathode is one in which the life of the headbar and the deposition sheet are the same. However, corrosion usually concentrates in a narrow zone across the face- of the sheet, resulting in breakages which, before the advent of argon arc welding, meant a loss of a 'complete assembly.Attempts to extend sheet life included use of thicker sheets, multitudinous protective coatings applied with varying degrees of success, re-rolling, and for a time, aluminium consumption was reduced when broken sheets found re-use as protecting strips. This latter economy became impracticable when electrode spacing was reduced for greater efficiency in power utilization.As an integral part of the electrode, the headbar was modified accordingly. Copper headbars, although more corrosion resistant, were replaced by aluminium due to a possibility of dissolved, copper promoting deterioration.Thicker electrodes and regulated spacing reduced internal shorting, whilst provision of knife-edge type supports on both contact and insulator ends of headbars aided in electrode centralising and continuous electrical conduction.After much experimeIitation, an assembly has been evolved which, with the aid of argon arc welding and tbe use of minimum additional aluminium, permits comparable headbar and sheet lives, combined with good electrical conduction throughout the life of the cathode.INTRODUCTION Over 300 tons of zinc are produced daily at Risdon from a purified zinc sulphate solution by electrolysis, the zinc being deposited upon all-aluminium (except for copper contact) cathodes. It is stripped in 72-hour cycles from the cathodes, melted and cast into the customary rectangular slabs.

Jan 1, 1958

By W. J. LANGRON

This paper describes the results of VLF-EM test surveys, using the Ronka EM-16 equipment, over a selection of environments in Australia and Papua.Using comparisons with known geology, drilling information and other geophysical work it is shown that the maximum depth of penetration of the method is about 100 ft but is considerably less than this in most areas.The author believes the method could aid in geological mapping and provide a useful adjunct to aeromagnetic surveying in some areas.

Jan 1, 1972

By K Kermanshahi, J Allen, MáHilden, M Powell, S Mwansa, S Palaniandy

Approximately 420 VertiMills« (VTM) have been installed in mineral processing plants throughout the world, mainly in tertiary and regrind applications plus several in secondary grinding duties. Metso Minerals (Metso) and the Julius Kruttschnitt Mineral Research Centre (JKMRC) have commenced a collaborative research program in stirred milling technology focusing on mill performance evaluation, model development and scale-up methodology. Industrial VTMs are being assessed using a consistent circuit survey protocol to evaluate the performance of VTMs in comminution circuits. The survey protocol includes identification and modification of sampling points, appropriate sampling techniques, controlled circuit stability, and best sample analysis practice. To initiate this study four surveys were conducted in the tertiary grind circuit in the Ridgeway Concentrator at Cadia Valley Operations (CVO) that treats the full circuit throughput of over 800 tph. To deal with the high feed rate the site opted to lead the world in the application of stirred mills by installing the largest VTM, at 3000 hp (2240kW) in closed circuit with a hydrocyclone bank. On average the operating work index was 13.1 kWh/t, reducing the secondary grind product by 40 - 50 ¦m to the required 80 to 100 ¦m range. The applied specific energy is relatively low in these low-intensity stirred media mills at 2.7 kWh/t. The size specific energy was 24.2 kWh/t-75¦m. Based on the survey and operating data the VTM circuit is performing well in this high-throughput tertiary grinding application, producing a sub-100¦m product.CITATION:Palaniandy, S, Powell, M, Hilden, M, Kermanshahi, K, Allen, J and Mwansa, S, 2013. VertiMill« - Development of circuit survey and performance evaluation protocols, in Proceedings MetPlant 2013 , pp 162-175 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

The theme of the conference is "excellence", an epithet of special significance in tertiary education. It appears in the mission statements, goals and plans to achieve them of most, and quite possibly all, tertiary institutions in Australia. In the context of excellence, this paper examines the current statue of professional education in the principal mining industry related discipline of Mining Engineering. It furthermore, identifies and discusses a number of special problems in mining education that the tertiary sector has long endured. Some of these problems are becoming acute, and solutions will have to be found soon in order for the industry to be assured of the supply of well motivated and appropriately qualified young engineers and scientists necessary to achieve and maintain the excellent to which it aspires.

Jan 1, 1989

By A Hanna

Quarries around Auckland have reached or are reaching the ends of their lives, which raises issues about rehabilitation. Significant volumes of 'cleanfill' are generated by the City, particularly during phases of urban renewal and development. Emplacement of the fill in quarries removes the problem of fill disposal and provides an opportunity for restoration of the quarry site.There is a compatibility between quarrying and cleanfilling because at quarries:Truck routes are already established Neighbours are accustomed to the effects and appropriate buffer distances have been established Bringing fill into a site attracts aggregate sales and is very efficient. Fill originates from construction sites and ad-hoc excavations and therefore it is not surprising that sampling has shown the quality to be variable. Both Winstone and the Auckland Regional Council have surveyed undisturbed soils in the region to attempt to determine natural background levels of common contaminant substances. Comparison of these levels with delivered fill shows that a high proportion of delivered materials can be regarded as mildly contaminated. Therefore the term 'cleanfill' is, in the Auckland region at least, a misnomer and the term 'managed fill' has been adopted.Historically and presently the only control on quality of 'cleanfill' has been some visual inspection. This leaves the fill operator open to potential liability for creating a contaminated site. Implementation of controls at WinstoneÆs operations has progressed slowly, over some ten years. This is mainly due to the perception that mobility of contaminants within and out of the landfill will be very limited because of the near-neutral pH and abundance of clay minerals in the fill. The methods of control and results of environmental risk assessments at WinstoneÆs Puketutu Island Quarry will be briefly described.

Jan 1, 2002

By Freeman C, Dingley W

Addition of sodium nitrite-borax, sodium hydroxide, sodIUm carbonate, lime, or sodium silicate reduced wear of forged steel balls and cast iron slugs in wet grinding a complex zinc-lead-copper sulphide ore in laboratory ball mills. Maximum wear reductions were 27 per cent (forged steel balls) and 33 per cent (cast iron slugs) with sodium hydroxide and nitrite-borax additives respectively.Potential measurements of balls and slugs during grinding, and analysis of the data in terms of corrosion theory demonstrated that corrosive wear had been reduced or prevented by these additives. Actual per cent wear reductions were not equated to the rate of corrosive wear because of the undefined interdependence between abrasion and corrosion in wear processes. The investigation verifies that in laboratory ball mills corrosion is significant in the wear of grinding media and wear can be reduced by corrosion inhibition and pH adjustment.

Jan 1, 1978

ONE of the phases of mining wide ore-bodies, such as are found in Broken Hill, is the laying-out and design of the sill floor gangway timber, When, in the above operation, a detail has to be repeated frequently, it is desirable in the interests of efficiency that that detail should be standardized as far as possible. Before arriving at a standard design e.g., a crosscut layout-it would seem necessary to compare its strength with some other unit of timber and see that the general design is at least as strong as the unit that has been taken for comparative purposes, In these notes no attempt is made to calculate the stresses to which timber underground is subjected, but merely to draw a comparison between the relative strengths of the various cross sections of timber in common use underground.It has been assumed for the purposes of comparison that the milling exerts pressure in a vertical plane only, and is uniformly distributed over any area. A beam supported at both ends, and with a uniformly distributed load, has the maximum bending moment at a point midway between the points of support, and equals- WL2 8 where W = load per unit length. L = distance between points of support.The bending moment also equals M-, where y M = modulus of rupture of the material in question. I = moment of inertia of the section of the beam about a given axis.Y = distance of extreme fibre from that axis. WL2. I The formula -8- = MY- only holds good until the elastic limit...

Jan 1, 1923

By Keet B. A, Waid J. S

The Gippsland Basin is one of Australia's most important producers of petroleum products. An inevitable byproduct of the production, refinement and transport of the millions of barrels of oil is thousands of tonnes of waste. These wastes are generated from the wellhead through to the petrol bowser and range from oily brines and coal tars to oil and petrol contaminated soils. The vast majority of these wastes are of a relatively low toxicity and most importantly are carbon-based and biodegradable. Current disposal practices tend to ignore the latter characteristic and inappropriate and/or expensive waste disposal solutions such as landfilling (tipping), incineration or ocean outfalls are the result. A very cost effective and environmentally friendly alternative is land treatment of such wastes. Landfarming, as it is called, has been successfully practiced in Europe for over a decade. Essential features of the system are: ò Application of a predetermined quantity of biodegradable waste in liquid, sludge or highly contaminated soil form, to pre-ploughed soil with concurrent addition of nutrients (N, P and trace elements) and lime to encourage bacterial activity. ò Harmless bacteria already present within the soil break down the carbon-based compounds into carbon dioxide, water and waste heat, WHILE concurrently generating new cells. The breakdown occurs over a period of weeks to months and continues with time with the extremely low levels of the more difficult waste types being the last to disappear. ò Further waste is applied to the soil at regular intervals. The treatment area may be dedicated to landfarming or may be used alternatively for agricultural purposes. Application rates vary but may be as high as 800 tonnes per hectare per year for wastes such as refinery sludges.

Jan 1, 1992

The Bulli Seam, New South Wales, comprises medium to low volatile bituminous coal, generally of coking quality. It is worked over an area embracing 300 square miles.Variations in several factors are found.1. The seam is somewhat disturbed and dissected by various structural features.2. This structure, and present topography, have resulted in depths of cover from very shallow to approaching 2,000 ft in the presently worked areas.3. Wide variations of seam thickness occur.4. Gradations of rank occur from place to place.5. Variations in seam gas content and wide variations in seam gas composition are experienced.6. Variations in coal strength occur.These factors may contribute to the occurrence of stress and gas phenomena in mining exploitation.INTRODUCTIONThe Bulli Seam, the most extensively worked seam in Australia, is the uppermost seam of the Illawarra Coal Measures, which comprise the southern portion of the Sydney Coal Basin. Generally, the rank of the seam and its assemblage of types make it ideal for the production of hard metallurgical coke. The thickness and relatively flat dips render the seam suited to mechanized bord and pillar mining, and this method is used almost without exception. At the north-eastern corner of the field, stress and gas phenomena have occurred during mining.Various data have been assembled on physical, chemical and geological conditions of the seam which may influence the occurrence of stress and gas phenomena. This material is presented in an attempt to explain the location of such phenomena to date, and to enable variations in conditions to be considered when future possibilities are being assessed.

Jan 1, 1963

The Porgera Joint Venture commenced production during September 1990. A small tonnage underground mine extracts high grade gold ore using small scale stopes. Conventional drill and blast methods are used for development and production mining. Ground support is effected with Splitset anchors, grouted rebar bolts and grouted cable bolts. Splitsets and grouted rebar can be installed by mechanised means. Vertical crater retreat, slot and massfire, and modified VCR stoping tech- niques are used at Porgera. Stopes are backfilled with a relatively strong cemented rockf ill. Future stope sequences require recovery of pillars beside and under filled stopes.

Jan 1, 1991

By Misra V. N

Upgrading of a Koolanooka magnetite iron ore sample provided by Kingstream Steel Ltd was investigated using low intensity magnetic separation (LIMS) and reverse flotation. The ore contained 38.6 per cent iron, 37.8 per cent silica, 6.5 per cent magnesia and 0.54 per cent alumina, with the main minerals in the ore being amphibole (42 per cent), magnetite (39 per cent) and quartz (14 per cent). The concentrate obtained after low intensity magnetic separation contained 66.6 per cent iron and 6.34 per cent silica with an iron recovery of 72 per cent. This concentrate was further treated by reverse flotation to increase the iron content and reduce the silica content to meet the requirements for direct reduction iron (DRI) feed grade.

Jan 1, 1999

The copper-clay deposits consist largely of goethite and clayey mudstones carrying native copper, cuprite, and chalcocite. The mudstones are of Ordovician age, are interbedded with Fe-Mn carbonates, and probably contained syngenetic iron and copper sulphides. The secondary copper minerals have been derived from post-Devonian weathering in situ and also by deposition from surfaee and underground waters draining the adjacent mineralized volcanic rocks.

Jan 1, 1969

Of the world's total production of gold the largest proportion comes from the more regularly consistent ore bodies, but in the aggregate an important part comes from those which are often irregular, uncertain and small. These smaller ore bodies are often high in grade and, as the capital required to work them is not large, they appeal to people seeking a quick and profitable return for a small outlay.These small mining concerns cannot afford detailed geological and petrological investigations and mapping, so they are very often dependent on local knowledge and experience which admittedly may be of really great value.Nevertheless the absence of skilled guidance may not only cause good opportunities for intelligent exploration to be lost, but discourage the seach for other ore bodies.lVIining engineers in the course of their travels in the examination of mines often come across such cases and also others where problems of finding lost ore bodies have been solved by the man on the spot. As records of cases are valuable and useful additions to the knowledge of ore occurrences, the writer now proposes to describe one such case coming under his observation in recent years.It is that of a small mine, known as the Idaho, at the southern end of the famous "Golden Mile" at Kalgoorlie (see Fig. 1). This mine has been a small and very erratic producer ever since it was abandoned by an English company which owned it forty years ago. Except for one period of four years it has always been owned and worked by parties of co-operative miners and during its time has gone through a tortuous career. Although it has often...

Jan 1, 1938

The principles of geometry and trigonometry are so continuously used by mining engineers for the purpose of accurately and intelligibly recording their measurements, that the writer is prompted to lay the following cursory remarks upon mine surveying before the members of this Institution in the hope of eliciting a free interchange of opinion upon details of this interesting branch of the profession. He proposes to deal with surveying only so far as it concerns the mining engineer, not to intrude upon the domain of the professional surveyor, and, in this instance, to discuss more especially that which may be termed the mechanical, rather than the mathematical side of surveying.In the latter part of the eighteenth century and the beginning of the present one, the usual underground surveying equipment in the English metalliferous mines, consisted of a magnetic needle in a fiat square wooden box of about 9-inch sides, a two-foot rule, a long cord, aud a stool, upon which to place the needle and box. The operator took his bearing by sending his assistant with the end of the cord as far in a straight line as the length of the cord would admit.On its being drawn that he held its end in one hand and placed the side of the compass-box against it with the other, and noted the bearing thus found either by a book entry, or by ticking it off with a piece of chalk on the board the compass lay in. He then measured the cord with a two-foot rule. It is needles to say that with these appliances the accuracy of the results were open to question, and mining surveying was not unduly popular.In the present day, engineers have the advantage of using instruments brought to such a state of perfection, and of employing such an exact system of underground surveying, that inaccurate work must usually be attributed either to lack of care, or lack of ability in the operator.

Concentrations of bright green material in the "Golden Mile" of Kalgoorlie, which carry particularly high gold values, are known locally as "green leader".This assemblage consists largely of quartz, sericitic muscovite, carbonates, and pyrite. Some of the sericitic muscovite contains vanadium, giving the rock its green colour. Vanadium oxides, including nolanite, are also present. Tellurides identified in this study are calaverite, altaite, petzite, melonite, and coloradoite. Native gold was found in most of the samples; some of the gold, at least, has been formed from the decomposition of gold tellurides.It is suggested that mineralizing solutions carrying gold and tellurium leached vanadium from the host rocks and subsequently deposited gold tellurides and vanadium-bearing minerals in the "green leader".

Jan 1, 1977

Gold in the stibnite veins of Costerfield, Victoria, was described in 1922 1, prior to any mineragraphic examination, as (a) free yellow gold (b) free rusty gold and (c) combined gold. The free yellow gold occurs in quartz and will amalgamate with mercury. The free gold of dull, rusty or copper-red colour occurs in massive stibnite and has been stated to resist amalgamation with mercury. The dull colour is only skin deep and the colour is bright when the rusty gold is scratched. The appearance of the rusty gold is spongy or cellular and it generally occurs near small cavities in the stibnite. The suggestion that the cellular character indicated the removal of a certain amount of stibnite leaving a residue of se.condary gold cannot be sustained.It now appears probable that the rusty gold is formed by the primary dissociation of a gold antimonide and is distinct in origin from the normal yellow gold which is deposited with quartz or stibnite from auriferous mineral solutions.The combined gold referred to in the earlier paper was the gold contained in the stibnite as revealed by assay. Such gold was at first thought to be either dissolved in the stibnite or else present as free interstitial particles too minute for observation in transmitted light in thin sections.Subsequent examination of numerous polished,surfaces disclosed the small particles of gold occurring in the grain boundaries in aggregates of fine grained stibnite 2. The assumption that all the gold in the stibnite, as revealed by assay, occurred in this way is now known to be incorrect, because limited amounts of a gold antimonide have been found in the veins.

Jan 1, 1952

By D David

Clearly a plant designed only to treat average ore at the nameplate rate will fail to achieve nameplate in any typical year. To insert the necessary capability to achieve nameplate it is common process engineering design practice that plant must be able to treat an ore with 80th percentile value (hardness or competence values for example) at the nameplate rate. In the authorÆs experience, apart from a couple of notable cases, this has been applied reasonably well as a principal, and with widespread success. However, in a number of recent instances it became clear that the use of the 80th percentile number would have resulted in significant under design of the plant. This paper makes the case that the 80th percentile, as a principal, has can have serious flaws and its use needs to be assessed on a case by case basis. The discussion in this paper is the first step in developing a new design principal, and the associated methodology for selection of a design value, that will ensure plants are designed to achieve their nameplate capacities.CITATION:David, D, 2013. Is an 80th percentile design point logical?, in Proceedings MetPlant 2013 , pp 6-12 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By K L. Temel, W P. Player

The underlying message of this paper is that investment in prospecting, exploration and mining in New Zealand is welcomed. The Government's policy with respect to Crown owned minerals is for continuing investment in prospecting, exploration and mining which is in accordance with good exploration or mining practice. To encourage continued investment requires a business-friendly environment. Government policies and initiatives to enhance the business environment for the minerals and coal exploration and mining industries are discussed in this paper. As well, new initiatives under consideration, which have the purpose of enhancing the investment environment, are discussed.

Jan 1, 1997

By Lees M. G, Vitnell B. W

The post-war need to increase coal production promoted an intensive drilling campaign. Ineffectiveness in core recovery inclined the coal industry towards percussion drilling rather than diamond drilling. The Joint Coal Board, recognising the greater potential of core drilling, has actively encouraged improvement in techniques and equipment. One outstanding need was a barrel which, over and above other improvements being achieved, would permit recovered core to be examined before it had been subjected to the increased fragmentation and displacement which to date has been inevitable except in core which has been drilled in solid sticks û as New South Wales coal rarely can be drilled. In conjunction with Triefus Pty Ltd a barrel with a split inner tube has now been evolved, as a result of which, core can be more accurately logged, division in to lengths for analysis more aptly made, any core loss more reasonably allocated to appropriate plies, and a greater percentage of core recovered û of the order 95 per cent and more. The one half of the split inner tube is lifted from the other and the logging completed before the core is disturbed.

Jan 1, 1957

By Nageswararao K

A series of tests was carried out on one of the rock-pebble milling circuits treating complex nickel ores at Kambalda Nickel Operations of Western Mining Corporation. A mathematical model to describe the behaviour of a 508 mm hydrocyclone was developed from the data.A "flat" reduced efficiency curve was observed for the system. This was attributed to a marked difference in the specific gravity of different size fractions of the feed. A modified approach in describing the shape or the reduced efficiency curve resulted in accurate prediction of the hydrocyclone performance.

Jan 1, 1981