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By Honeycombe R. W K, Greenwood J. N

Powder metallurgy has been developed rapidly in the last twenty years by overseas metallurgists. The technique of making the powders and their subsequent pressing and sintering into useful forms has' only been introduced into Australia under the stress of war-time economic conditions.The technique involved has very little in common with our usual methods of fabricating engineering alloys by melting the ingredients to a homogeneous mass, followed by casting to shape or casting to ingot form and shaping by application of pressure-so-called mechanical working. On the other hand, the technique includes operations, such as milling and sizing, familiar to the primary metallurgists.The compacting of metal or other powders finds important application in two outstanding fields of engineering production: (a) in making porous bearings and contact brushes, in which such a material as powdered graphite can be incorporated; (b) in making cutting tool tips of hard -carbides, which have a melting point too high to make casting feasible, and which would be too brittle in the cast condition in any case. In both these cases; the final article can be made of the desired shape and size (subject to shrinkage allowances) whilst the compact is in a soft and readily machined condition a consideration of great importance in connection with the hard carbides.In order to develop the necessary equipment and technique and at the same time to assisil in the war effort, it was decided to divert the research work of the Metallurgy Department of the University of Melbourne to the problems associated with the production of hard carbides from local raw materials and the sintering of such into tips for cutting tools. Since this work was started at least two industrial concerns have started to produce these materials in the Commonwealth.The work. to date has included (a) the purification of crude cobalt oxide from Risdon and the reduction of this to metal Particles of less than 10 p. diameter; (b) the production of tungsten powder from King Island scheelite and its conversion into tungsten carbide with particle size less than 4 p. diameter; (c) the sintering of the latter product, using the former as a bond; (d) the production of titanium carbide from titanium dioxide; (e) the separation of columbium and tantalum oxides from a Northern Territory tantalite, and the conversion of these into the respective carbides.

Jan 1, 1942

Metana Minerals commenced life in 1970 and graduated to a mining company in 1981 with the opening of a small alluvial tin-tantalite mine at Wodgina (W.A.) The present board of directors assumed control of the company in 1978 and established the exploration and development philosophies that have guided the company's expansion to its present status as an emerging diversified miner. An ability and willingness to raise equity capital when required has been a feature of the company. Company activities include exploration for gold, diamonds, heavy mineral sands, polymetallic (base and precious metals) deposits, strategic minerals, rare earths, oil and gas in a geographical distribution covering the entire Australian mainland Metana owns and/or operates four gold mines (Reedy, Mt Magnet, Youanmi and Howley) and at the time of writing is developing a fifth gold mine - its first underground mine - at Rothsay. In contrast to many similar or larger sized companies, Metana undertakes most activities itself rather than through the use of consultants or contractors. In-house services include: analytical and metallurgical laboratories, plant engineering design and construction, drilling and mining (earthmoving) Metana Minerals has established an enviable reputation for technical excellence and this expertise has placed the company in a sound position to continue its growth pattern into the future. This growth will be achieved through a combination of low cost and successful exploration and acquisition of suitable mines either directly or through corporate activity.

Jan 1, 1989

This Department handles all ores prior to blast-furnacing, the object of the operations being to mix the lead-bearing material with fiuxes, eliminate sulphur from the mixture, and produce a homogeneous sintered product which is chemically and physically suitable for treatment in the blast furnaces.During the financial year ended the 30th June, 1937, the tonnage of charge treated was 458,960 tons, containing some 183,470 tons of lead and 8,504,000 oz. of silver.The quantities of the principal components of the charge treated were as follow:-

Jan 1, 1937

The lead concentration of flotation feed ore slurries is determined using two ?-ray absorption gauges mounted directly on a 6 in. diameter flotation feed pipeline. One gauge is a conventional "density" gauge using CS137. The other is a "lead-sensitive" gauge, which depends on the preferential absorption. by lead of 225 key y-rays resulting from Compton backscatter of CS137 y-rays.Gauge outputs are combined using an analogue computer the output signal of which is directly proportional to the lead concentration of the pulp. The accuracy of measurement of the pulp lead concentration is ± 3·6 per cent for ore slurries with lead concentrations in the range 0'07-0·16 g/c.c. and pulp densities 1.43-1.60 g/c.c.This paper sets out the development of the technique and details are given of the two experiments (1964, 1966) conducted in the plant at North Broken Hill Limited. The installation of the two-gauge system inthe plant during May 1968 is described. Details are given of the calibration technique used and the results obtained.

Jan 1, 1969

Characterisation of Manganese Ores

Sep 13, 2010

The material presented in this paper describes experimental work to determine the effect of variations in suction nozzle design upon inlet flow conditions. Four entrance profile shapes were examined under controlled conditions of slurry flow and it was found that the straight ended nozzles had consistently higher entrance losses than the straight taper or the ellipse, and that the circular arc profile nozzles were the most efficient. Subordinate considerations were the measurement of the quantities and the forces involved.As the work progressed, three distinct phases in the pattern of flow were apparent and the static pressures in each were carefully examined. An inlet zone was found to be unstable in changing boundary conditions, a transition zone was largely independent of slurry density and in a zone of stability the pressures were found to be directly related to the characteristics of the flowing pulp. In this zone pressure measurements were reproducible within ± 2 per cent regardless of changing boundary conditions.The effect of varying the "1" parameter of nozzles with a part circular entrance profile was examined and it was found that flow conditions approaching the ideal were obtained when the radius of curvature was between 0·40 and 0·550.

Jan 1, 1966

In the Ngakuru area, zeolite deposits occur in late Quaternary lake sediments and ignimbrites. The deposits are associated with sinters, hydrothermal eruption breccias, and quartz-adularia altered fault breccias: all indicators of a shallow epithermal environment. Several of the deposits are adjacent to epithermal gold prospects. Zeolites are most abundant in lacustrine tuffs of the Ngakuru Formation, a 100-300 m thick sequence of siltstone, tuff, diatomite, sandstone and conglomerate. The formation overlies the Ohakuri Ignimbrite dated at c. 270 Ka, and is unconformably overlain by alluvial sands and gravels which are younger than 20 Ka. Individual zeolite deposits contain 30-80 per cent zeolite over a thickness of up to 45 m in thinly stratified tuff beds. The tuff beds are locally overlain by diatomite. The tuffs are composed mainly of glass shards and pumice clasts, with minor volcanic plagioclase, quartz and biotite crystals. Glass shards in the tuffs are replaced by the silica-rich zeolites mordenite and clinoptilolite. Amorphous silica (opal A), opal-CT, K-feldspar and smectite are also present. The distribution of the Ngakuru Formation is controlled by northeast trending normal faults, which separate it into the Ngakuru and Guthrie grabens. A silicified (quartz-adularia altered) hydrothermal breccia along one of the fault zones suggests that the faults acted as feeders for heated water that caused the deposition of the zeolite minerals. Some of the zeolite deposits are adjacent to sinters and hydrothermal eruption breccias. The location of the sinter about 20 m above one deposit indicates that the zeolites were formed at a depth of 20 to 70 m below the paleosurface. The hydrothermal eruption breccias contain clasts of altered ignimbrite, which contain geochemically anomalous gold and silver values. By analogy with their occurrence in active geothermal systems in the Taupo Volcanic Zone, mordenite and clinoptilolite in the Ngakuru deposits probably formed at temperatures of 60-150oC from near-neutral pH waters as a result of interaction with glass-rich tuff beds. The Ngakuru zeolite deposits are therefore interpreted as shallow hydrothermal alteration zones within larger epithermal gold-bearing systems.

Jan 1, 2002

By Bratt G. C

When zinc is electrowon from concentrates or residues of high manganese content, the zinc sulphate electrolyte may contain high levels of manganese. The manganese level is usually controlled by removal of manganese at the anode as the dioxide during the zinc electrodeposition stage.By increasing the temperature of an electrolyte containing 8 gll manganese from 35°C to 90°C, decreasing the acidity from 100 gll to 30 gll, reducing the current density from 432.A.m-2 t6 286 A.m-2 and using new lead anodes containing over 0·75 per cent silver, the current efficiency for manganese dioxide removal was .increased from less than 1 per cent to over 20 per cent.At the same time the current efficiency for zinc deposition was maintained above 90 per cent by additions of high molecular weight cationic polyacrylamides to the cell. By utilization of these conditions in a small number of cells, the manganese level in the circuit could be economically concrolled to any desired level.With these conditions the formation of the dioxide changes from an indirect route, via Mn04-, to a direct oxidation of Mn2+ to Mn02.The incorporation of impurities such as Pb, K, NH4, Cu, Ni, or Fe makes the deposit unsatisfactory for direct use in Zn - Mn02 dry cells. The deposit structure changes from cryptomelane at low temperature to y3-Mn02 at high temperature.

Jan 1, 1975

This paper is in two parts. The first covers the evolution of dredging leading to the development of the æNZ typeÆ large dredge and the second, current alluvial gold recovery practice in NZ. NZ was the first country in the world to adapt the bucket-ladder dredge to alluvial gold recovery. Between 1857 and 1907, gold worth (at today's NZ price of about NZ$600/ounce*) over $11 billion was exported û from a country with well under one million people at that time. Over 200 small dredges operated, mostly on the Clutha River, around the turn of the century, however by 1940, only 20 or so large machines remained, and the last of these, the 4000 ton 'Kanieri' ceased operations three years ago. Recently recognition of the superior digging power of the hydraulic backhoe and reintroduction of the simple 'trommel and riffleÆ plant with about 80 m3 /hour capacity has led to a proliferation of static and floating plants, there being at least 50 currently in operation on the West Coast and in Otago. There are signs however, that the process of evolution of such small unsophisticated plants into larger, more efficient units has begun again. * At the time of writing (October 1984) NZ$l. 00 = US 50ó. NZ dollarsare used throughout this paper.

Jan 1, 1985

The emergence of China as a global economic power has not been without its birth pangs and the current coal market is testimony to this. Traditionally the coal market has been controlled by mature economies that functioned along balanced lines of supply and demand. The emergence of China and India as major forces in the international market has shifted this balance of power from mature economies to the developing economies of China and India. Of late Chinese Central Government policy has caused wide swings in the supply of Chinese coking coal and thermal coal to the international Asian markets. This has resulted in huge increases in demand for coal from producers in Australia, Canada, Indonesia, USA and Russia. Additionally since the late 1990s the liberalised Chinese economy has been growing by between nine to 12 per cent per annum. The corresponding rise in the standard of living of their 1.4 billion people has resulted in a strong demand for raw materials, initially met by domestic production and more recently met by the importation of raw materials including iron ore, oil, coking coal and thermal coal. Commensurate with this growth in China has been the emergence of India (pop one billion) as another major developing economy in the region. Whilst the Indian standard of living is lower than that of the Chinese, this subcontinent still has some 300 million people with middle class consumption demands. India is a major importer of oil, coking coal and thermal coal. It exports iron ore to China with growth parallel to China (seven to nine per cent per annum). These combined new demands from India and China have put unprecedented pressure on the global supply of coking and thermal coals. These pressures are reflected in the current world spot prices for coking and thermal coals which are at historically high levels. Whilst current demand from China and India is high it is anticipated that new projects will partially satisfy this increasing demand. Expectations are that overall thermal and coking coal prices will rise steadily. This paper seeks to identify the potential effects of Chinese and Indian economic growth on the international markets for coal.

Jan 1, 2004

The history of soft and hard rock underground mining is blemished with regional instabilities of mine workings. Whilst the potential consequences of regional instability events are recognised to be high, there is a false perception that the probability of them occurring is very low. In fact, Australia has averaged more than one event per year for the past 20 years. At least five fatalities and over $100 million of losses have been associated with the events. As such, they are a core risk to underground mining and have a significant effect on the quadruple bottom line of business û safety, environment, community acceptance and economics. This paper explores the important roles that risk management has in reducing the probability and consequences of regional instabilities. It concludes that education and continuing professional development are essential elements for effectively managing the risk.

Jan 1, 2003

An oxide ore heap (80,000 ton assaying 2 per cent copper) and a sulphide ore heap (300,000 ton assaying 1·7 per cent copper) are being leached in series in a closed circuit system. The ore is friable and weatherseasily giving severe percolation problems. These were eased by applying liquors at 235 gal/min to trenches 2 ft wide and 6 ft deep along the full length of the heaps.Cementation recovery was improved from 20 per cent to over 80 per cent by regular intermittent agitation of the iron using a back hoe unit.Liquor pH is controlled by acid addition, and iron content is controlled by a bleed-off set according to predictions made from a pH-Eh diagram drawn for the liquor components. These controls, together with acyclic wetting and draining procedure, have raised production from 6 ton/week to 10 tdn/week of 80 per cent copper.

Jan 1, 1968

This paper describes the behaviour, under creep conditions, of a cast lead creep specimen consisting of five crystals, the boundaries of these crystals being substantially at right angles to the direction' of tension, i.e., across the long axis of the specimen. This particular specimen was obtained in an attempt to produce a single crystal in the manner described in the appendix of a previous paper (1).Thus, the specimen was of the same shape and size, was composed of the same purity lead and received the same preliminary treatment as the single crystal test-pieces.The object of the experiment was mainly to observe the effect of the crystal boundaries on both the deformation of the test piece and the process of recrystallisation and to compare the creep rate of the test-piece with that of a specimen consisting of one crystal only.EXPERIMENTAL METHODThe specimen had an effective test length of 10 cms. and a cross $ection of 0·5 in. x 0·25 in. In Fig. 1 is given a sketch of the specimen to scale showing the positions of the crystal boundaries on all four surfaces. Except for those of crystal No. 4, which was confined to approximately one-half the cross section of the specimen, the boundaries of each crystal traversed the four faces.The specimen was mounted in exactly the same manner as the single crystal specimens. During the creep test, it...

Jan 1, 1941

This technical note describes a problem with WANG82, a ventilation network analysis programme. The problem was highlighted by Renison Ltd when using the programme on large, complex networks. Under certain circumstances the programme produced incorrect results or failed to converge to a solution.

Jan 1, 1986

By Holly J

The period following World War II has seen many changes in stoping techniques at The Great Boulder Gold Mine. The new methods resulted in improved unit production figures, and have given some relief from the rising worldwide cost spiral in the post war years.Significant production figures are shown graphically in...

Jan 1, 1956

By Camier R. J, Perry G. J

Extensive deposits of brown coal exist in the Gippsland Basin, primarily in the Latrobe Valley. The total quantities of economically winnable coal in this region of Victoria and in other smaller fields are large enough to adequately assure Victoria's future electricity needs and to also provide large quantities for alternative applications, including liquefaction. As a result of the recent conflict in the Middle East attention has again been focussed on the production of synthetic fuels from coal. There have been many investigations over the years into the production of oil from Victorian brown coal. The purpose of this paper is to summarise the scope, objectives and major findings of these studies, with the emphasis on the direct hydrogenation route for converting brown coal to oil. The principal alternative processes are carboniastion and hydrotreatment of the product tar, or gasification and Fischer Tropsch synthesis of liquids from the product gas. The attractions of Victorian brown coal which have encouraged these studies include: ò the vast reserves of Victorian brown coal and the favourable conditions for low cost mining, ò the high quality of the coal (low ash, sulphur and nitrogen contents), ò the high reactivity of the coal giving high yields of product in hydrogenation to liquid fuels, ò the extensive data base available on the resource and its characteristics, and ò the availability of a skilled workforce and extensive infrastructure in the Latrobe Region to support a major resource development project. These advantages have been partially offset by: ò the high moisture content of the brown coal and the cost of drying, and ò the priority previously given to electricity generation in the allocation of the brown coal resource.

Jan 1, 1992

By J Taylor, L Richards, M McKenzie

When a collapse in its services shaft caused rapid gas build up and its premature closure in. 1951, the Blackwater Mine at Wiauta was in full production with significant ore reserves yet to be mined. A total of nearly 23 tonnes of gold was produced from the mine during its 44 year life. It was New ZealandÆs deepest underground mine, producing gold from an extensive sub-vertical mineralised quartz reef that averaged 0.6 m in width. Mining was by stoping between adits and short shafts, latterly with the main mine access through the 840 m deep Prohibition shaft. Macraes Mining Company Ltd are presently investigating the possibility of reopening the mine. This paper outlines a preliminary assessment of the main geotechnical factors for achieving the reopening, using recent exploration and old mine information. The greywacke host rock mass in the vicinity of the quartz reef has been evaluated using both these sources, and the paper discusses how the geological structure, intact and rock mass strengths, the rock mass defects, in situ stresses, and groundwater inflows may effect the reopening and support of the prohibition shaft, the excavation methods and support for a new supplementary shaft, and the likely excavation and support requirements for working adits and stopes in the rejuvenated mine.

Jan 1, 1996

By Met M, Orr C. W, Met B. E

As was mentioned in the last paper of this series(l), magnesium was added to lead with the idea that it would act as a de-oxidiser. The magnesium lead alloys give rise to an inter-metallic compound of the composition Mg2Pb(2) and it has some remarkable properties. It is known to disintegrate on standing in the atmosphere and it confers this property also on lead alloys in which it occurs. Magnesium forms a solid'solution with lead, and according to Kurnakow, Pogodin' and Vidusova(S) the limits of solubility are as follow...In conformity with the practice used in preceding series, the limit of concentration used in the present investigation was 0.1 %. Accordingly, it would be expected that all the alloys used would consist of the solid solution and the detrimental Mg2Pb would be absent. Whilst this was the case, it...

Jan 1, 1939

By Litvinenko V. I

Being a source of structural materials for many centuries, the modern image of the ferrous metallurgy is burdened with obsolete technologies with disregard towards new environmental protection requirements. The production cycle of metallurgical products have two clear-cut stages: I . production of liquid metal and casting into steel billets; and 2. processing of steel billets in solid state under high temperature to produce various shapes and profiles of metal products. Plastic deformation of metal at the second stage is least associated with environmental pollution and is presently being provided with more and more advanced equipment.

Jan 1, 1999

Predicting the future is a task that should always be delegated. If that is not possible, then stating your views confidently, but retrospectively, is preferable. Hindsight encourages clarity of thought and sharpens perception. When all else fails one can look back into history and see the trends, evaluate the current situation and project it a little way into the future - in this case 10 years. In exploration the rate of change has been increasing over the past 20 years. With expected developments in technology, legislation, and their sociological impacts, we will see such rapid change over the next decade as to make us uncomfortable, unless we are prepared for it.   The social obligations of our industry also have changed enormously over the past 20 years and are still changing. This will lead to further changes in the way we conduct our business if we wish to stay in business. As exploration technology improves, a further dimension is added by the expectations of the communities in which we operate. This extra dimension needs to be quantified so that we not only keep up with current developments but also get ahead of the game. This paper is based on the New Zealand experience, some of which will be familiar to mineral explorers in other countries.

Jan 1, 1997