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Comparison of Grinding and Liberation Processes for Stalky Biomass Materials as a Prerequisite for Production of Energy Pellets with High Calorific Value Pelletising biomass, especially straw and stalky materials, requires a product specific size reduction and liberation. However, moisture content plays an important role in palletising and also affects the energetic properties of the biomass. The paper illustrates the characteristics of the mentioned type of biomass and specifies the necessities for production of energy pellets. Defined requirements for biomass energy pellets will be shown based on relevant standards. The work focuses on a comparative investigation of the straw fibres after grinding with hammer/impact mill and after the liberation of the straw fibres with twin-screw extruder (two different communition units). A traditional hammer mill as well as an hydrothermal process taking place in a twin-screw extruder were utilised. Results of the grinding and liberation of rye and wheat straw fibres are discussed based on a detailed particle characterisation (particle size and shape distribution). Besides high calorific value the main pellet quality parameters are mechanical stability, abrasion resistance and further combustion technical characteristics. The particle size distribution displayed optimum characteristics for the combustion processes to be carried out in a furnace. The durability of the pellets produced from straw fibres liberated with twin-screw extruder was comparatively better then that prepared with the straw fibres after grinding with impact mill. Particle size distribution, abrasion values and the strength characteristics showed a good correlation with each. The high presence of N and S would result in high NOx and SOx emissions, where as the high concentrations of Cl would corrode the furnace. These chemical properties of the straw would restrict its usage in small scale furnaces.

Sep 13, 2010

By Kasai H, Hibi T, Matsuishi S

Coal oil mixture (COM), a liquid fuel pro- duced by mixing together coal and heavy oil on the 50-50 basis, has been brought to a level of practical use in Japan, being actually employed by a oil fired system at Yokosuka Thermal Power Station of The Tokyo Electric Power Co., Inc. A COM Production Plant, built in Onahama which is located about 160 miles from Yokosuka, required COM to be transported by sea. Mitsubishi Heavy Industries, Ltd. therefore performed a series of studies to develop a spe- cialized COM carrier, the world's first of its kind. Long lasting high stability is of pri- mary importance to successful use of COM. Much have been done in the way of research on stability of COM in the static storage, and the mechanism of COM static: stability is almost completety known. On the other hand, the knowledge about the COM dynamic stability, such as the stability while being transported aboard the COM carrier at sea, is still limited at the moment. The motion of COM aboard the COM carrier and how COM would settle were studied by tests. A visualization test on the COM behavior under dynamic motion was also performed and the mechanism of COM dynamic stability was analysed. The tests showed that the ship rolling motion had @n effect of promoting the settling of coal content of COM in the cargo hold. And studies were also made to device a method for esti- mating the settling quantity of coal during sea Transportation.

Jan 1, 1987

On the more important mines it is almost essential to have a general plan of the surface. A special feature of this plan should be the indication thereon of a suitable arrangement of contour lines, either wholly over the surface of the property or at parts where may seem most useful. The importance of having these contours marked on the plan will be best appreciated by the engineer, in selecting the best available site for a proposed new plant, in locating a tramway, in connecting the surface with the underground workings to the best advantage, or in solving many similar problems that come within his province. The closer the contours are together vertically the better, the limitation being the trouble and expense of getting them on to the plan. They may range from five to fifty feet apart but a distance of ten feet will be found, in most cases, to be the most useful.In deciding the datum level from which these contours are to be measured, it is best to depart from the ordinary sea level datum, and use instead the highest available point on the property. This datum will be called zero and all levels will be reckoned so many feet below it; thus by a contour marked 160 on the plan, it will be understood that the level of the plane of the contour is 160 feet below the highest available point on the property. This system of measuring levels downward is readily suggested from measuring the depths of shafts from the brace or of excavations from the original surface.

By P Meehan, R McAree, Z Guan

Equipment maintenance is 30 - 50 per cent of the operating costs for a typical mining company. While this is substantial, its importance is beyond its significance as a cost heading. Modern mining requires large amounts of investment in capital infrastructure and equipment to produce a product sold at a low unit cost. To stay competitive, such a business has to focus on full realisation of its capital investment, ie sustained production at high levels. Maintenance plays an essential role in achieving this goal. Mining companies typically use a mix of breakdown or corrective maintenance, planned maintenance, and some condition-based maintenance. The share of breakdown maintenance has been coming down through more effective planned maintenance and better condition monitoring tools. Planned or preventive maintenance (PM) is playing an increasingly important role in todayÆs mining maintenance. This is the suite of inspection and repair/replacement actions performed at scheduled time intervals as part of a preplanned activity. The activities are scheduled well in advance and, usually, the current wear-state of the machine is irrelevant. For example, the replacement of a major gear may have been planned 18 months in advance; replacement is carried out when the time comes regardless of the actual condition of the gear. The PM costs are significant and include direct cost of parts and labour as well as the opportunity cost of lost production while the machine is under maintenance. It is important to identify the optimum PM effort because over-maintenance should be avoided as much as under-maintenance. A new concept called severity-based maintenance is introduced in this paper. We have seen that measuring equipment ageing in mining merely by counting the engine hours is a very imprecise way of planning and scheduling maintenance because the damage accumulated in one hour varies enormously from operator to operator and with changing pit conditions. We recommend continuous monitoring of duty on all major equipment. This is feasible without having to fit out the machine with an army of sensors because most of the physical sensors required by dutymeters are already installed and maintained as part of the existing performance monitors. While the investment is modest, the potential benefits are huge and can be grouped under three headings:Immediate benefits will come from providing operators with direct feedback on the effect of their behaviour on machine health and training them to use this feedback to correct their operating style. The equipment can operate closer to the limits of capacity, producing more without unduly sacrificing the availability by monitoring and controlling the severity of the operation, ie the duty on the machine. Longer term benefits accrue from establishing correlations between actual time to failure data and measured equipment duty and using these correlations to optimise maintenance effort as well as planning new equipment purchases and warranty conditions.

Jan 1, 2002

By R J. Goldfarb

Reduced intrusion-related gold deposits have become a new, low-grade, large-tonnage exploration target during the last decade. The best recognized examples of such deposits are recognized throughout the Tintina Gold Province of the northern North American Cordillera. Because such examples may have many features in common with orogenic gold deposits, such as anomalous Bi, W and Te, low salinity and CO2-rich ore fluids, and a spatial/temporal association with igneous rocks, confusion and controversy have now become commonplace in classification of many gold deposits formed along convergent margins. The best discriminators of IRGS are likely to be their: +        regional location in deformed shelf sequences on the inboard side of a series of accreted terranes and within terranes that also contain important tin and (or) tungsten deposits; +        local spatial association of gold ores with cupolas and contact aureoles of relatively reduced, alkaline-leaning, and volatile-rich plutons; +        post-deformational timing of gold deposition; +        extremely low sulfide content (commonly <1 vol %) of ores within igneous bodies and the outward zoning, through proximal skarns and to distal base metal-rich veins, from the causative pluton; and +        low grades (<1 g/t Au) of auriferous sheeted vein systems in pluton cupolas.

Jan 1, 2005

Since its inception in 1962, the Julius Kruttschnitt Mineral Research Centre has adopted the view that an effective method of training highly qualified engineers for the mineral industry is the pursuit of postgraduate research programmes conducted in operations, that is, in the mines and processing plants of the industry which the research serves. The paper describes how this is achieved in practice, at little or no cost to the taxpayer, and explores the strengths and weaknesses of this approach in the context of a dual mission for the Centre: 1. The postgraduate training of engineers for the mineral industry. 2. The production of useful R &I) for the mineral industry. Topics discussed include financing, relationships with industry and Government, the maintenance of academic excellence, research style, the marketing of research, and limits to growth.

Jan 1, 1989

The Oregon-Idaho graben evolved after widespread tholeiitic flood basalt volcanism associated with the arrival of the plume head of the Yellowstone hotspot beneath southeastern Oregon approximately 17 - 16 Ma. The north- to north-northeast-trending, 50 km-wide graben evolved between 15.5 and 10.5 Ma during east-west extension. The graben is part of a middle Miocene back-arc rift (1100 km long) that includes the northern Nevada rift, the Baker and LaGrande grabens, and the Chief Joseph dike swarm of the Columbia River Basalt Group. The graben ceased to be a volcanotectonic depression as the cross-cutting western Snake River plain began to evolve at approximately 10.5 Ma. At about 14.3 Ma and continuing to approximately 12.6 Ma the Oregon-Idaho graben began to break up into subbasins that were bounded by intragraben fault zones. The break up was accompanied by a change to calc-alkaline volcanism that persisted within the Oregon-Idaho graben until 8.1 Ma, approximately 2.5 million years after subsidence within the graben ceased. Three intragraben fault zones have been identified and a fourth is inferred. The easternmost, the Devils Gate fault zone, coincides with the magmatic axis of the graben at approximately 14.3 Ma. By approximately 13.5 Ma the magmatic axis had shifted to the west along the Dry Creek Buttes and Wall Rock Ridge fault zones. A diffuse magmatic axis developed at approximately 12 Ma farther to the west where the fourth intragraben fault zone is inferred. In addition to serving as conduits for the ascent of basalt, basaltic andesite, rhyodacite, and rhyolite magmas, the zones focused the discharge of large geothermal systems. The intragraben fault zones display a common evolutionary pattern. The 2 to 3 km-wide zones initially control the distribution of facies in volcaniclastic sediments and the location of basalt hydrovolcanic vents. During this stage, the fault zones may have had no surface expression other than a low elevation change on a relatively low-relief landscape. As relief developed by continued deformation along the fault zones, strike-length of individual faults increased and weakly consolidated volcaniclastic sediments, silicified sediments and hot-spring sinter, and palagonite were eroded from the uplifted blocks and deposited in neighboring subbasins. It is during this stage that the large hot-spring precious-metals bearing prospects evolved. Displacements of over 150 m on a few faults within the zones and possible reversal of the sense of displacement along the zones occurred in this final stage of development. Locally, the fault zones were remobilised during the subsidence of the cross-cutting western Snake River plain. The intragraben fault zones within the Oregon-Idaho graben illustrate the relations among syntectonic volcanism and sedimentation and the evolution of geothermal systems within continental rift systems.

Jan 1, 1995

By P. S. B. STEWART

As part of a continuing study of mechanisms of breakage, the grinding at Nairne Pyrites Pty. Ltd. was traced by the addition of barytes and the results compared with parallel small scale laboratory tests. It was confirmed that the same basic mathematical functions described the behaviour of the full scale ball mill as those established in the small scale mill. However, an additional classification function was required to define the behaviour for the rod mill and was evaluated as a function of size from the experimental data. The classification and grinding of the pyrites ore was assessed from steady state size distributions around the circuit.

Jan 1, 1971

The Physical Basis of Non-Random Breakage in an Iron-Oxide Ore Hosted Copper Gold Ore

Sep 13, 2010

The Hishikari gold deposit, discovered by the Metal Mining Agency of Japan, has become a giant class epithermal gold deposit with the highest grade of gold yet recorded in the world through detailed exploration and development by the Sumitomo Metal Mining Co Ltd. The exploration strategy involved a regional approach combining geological and gravity surveys over a 900 km2 area which had historically produced over 120 t of gold. These surveys were carried out to grasp the common geologic features of epithermal gold deposits in the survey area. A genetic model for epithermal gold deposits in the area under regional survey was also considered based on detailed research of the Kushikino epithermal gold deposit which was in operation at that time. This model was applied to the targeted areas, and important relationships between mineralisation, host lithology, intensive propylitic alteration and gravity highs became apparent. The Hishikari block was selected in this way and bonanza gold was discovered during drilling. Since the development of the Hishikari mine, information useful for further exploration for the same type of deposit has been accumulated.

Jan 1, 1995

Willyamite from the type locality, Consols mine, Broken Hill, N.S.W., has been re-examined, and found to consist of zones with widely different Co:Ni ratios. The name willyamite is redefined to include the portion of the (Co, Ni)SbS series with cobalt in excess of nickel. Willyamite is pseudo-cubic, with the three axes equal to within 0·001 A.

Jan 1, 1970

By R L. Chaney, M Mahoney

Mine and ore beneficiation wastes and smelter contaminated soils often cause phytotoxicity and threaten adverse environmental effects if not remediated. Science has clarified both the risks from soil metals and methods to alleviate those risks that can be applied at low cost. Phytoremediation is a family of plant and agronomy based technologies to deal with environmental aspects of sites requiring remediation. If valid risk assessment indicates that metals comprise risk, phytostabilisation may be used to alleviate that risk for most contaminated sites. In particular, Zn-Pb, Cu and Ni mine and smelter sites are readily remediated by making the soil calcareous and fertile, with added organic and metal sorbent amendments that include soil microbes to ‘revitalise’ the soil. In each case, the soil fertility and causes of phytotoxicity should be clarified by agricultural soil extractions, and the combination of amendments required to improve fertility and reverse phytotoxicity identified and found locally. In contrast with phytostabilisation, phytoextraction/phytomining uses rare metal hyperaccumulator plants and agronomic management to maximise annual phytoextraction of soil elements into plant shoots for harvest, ashing and use as a metal ore. Plants that accumulate more than two per cent Ni in shoots, and yield 10–20 t ha-1 dry biomass yield 200–400 kg Ni ha-1, which has value greater than all common agricultural crops. Considering the value of elements, existence of hyperaccumulator plants and demonstrated agronomic management for Ni phytomining, it is clear that mine sites and Ni mineralised subore-grade serpentine soils can be phytomined economically as an agricultural mining technology. A team developed agronomic methods and improved cultivars of Alyssum, which can be profitably grown on temperate zone Ni mineralised or contaminated soils. Plant species for tropical ultramafic soil materials have been identified. Phytoextraction is also strongly needed to remove Cd from rice soils to prevent human disease from soil Cd.CITATION:Chaney, R?L?and?Mahoney, M, 2014. Phytostabilisation and phytomining – principles and successes, in Proceedings Life-of-Mine 2014 , pp 3–16 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By Parker A. J, Ruane M, Wadley L. G B

Copper, sulphur, nickel, cobalt, palladium, silver, and gold can be recovered from the copper sulphide precipitated from the "copper boil" of the Sherritt-Gordon nickel process used at Western Mining Corporation's Kwinana nickel <refinery. The method is based on an oxidative ammonia leach of copper, nickel, and the precious metals at temperatures below 40°C to produce, in part, elemental sulphur, in the residue. This is followed by heating to decompose thiosulphate and remove some ammonia with precipitation of some of the copper, palladium, gold, and silver. Addition of sulphur dioxide to pregnant liquor precipitates copper, as either Chevreul's salt or copper(I) ammonium sulphite, together with the remaining gold and silver. Less than 10 per cent of the dissolved palladium and less than 1 per cent of nickel and cobalt precipitate to this stage.In one option, the Chevreul's salt is dissolved in a solution of copper(II) sulphate, acetonitrile, and water to generate a solution of copper(I) sulphate. Gold and silver do not dissolve. The solution of copper(I) sulphate is thermally disproportionated by distilling acetonitrile to give exceptionally pure copper powder, with desirable characteristics for powder metallUrgy. Nickel, cobalt, and ammonium sulphate are recovered from the motherliquor of the Chevreul's salt precipitation by return to the Sherritt-Gordon process, where recovery procedures already exist. Palladium is recycled for eventual removal as a sulphide with the gold and silver.In the other option, solid copper(I) ammonium-sulphite is <thermally disproportionated in water at 150°C to copper powder.

Jan 1, 1978

Geochemical data on Australian granites and pegmatites, and the mineral components of these rocks, are compared with that obtained in similar studies in the U.S.S.R. and elsewhere.The geochemical character of tin granites and the trace chemistry of their component minerals, particularly biotites, have some significance as ore guides in prospecting for tin.The primary geochemical dispersion of tin can be readily tested both in the laboratory and field by colourimetric methods, after volatilization with ammonium iodide, using modifications of the method described by Wood (1958).Secondary dispersions of tin in residual soils or alluvia can likewise be readly tested by rapid colourimetric methods in the field, but simple hydraulic methods, handling larger sample volumes, give reliable outlines of dispersion patterns.INTRODUCTIONThe search for tin ores, whether lode or placer in type, is usually directed on genetic grounds to country within or adjoining acid intrusives.A long established means of prospecting is to test samples for cassiterite by panning or other hydraulic separation.These methods can be used on crushed lode material or the natural materials from placers.With the advent of new techniques for extraction and for colourimetric analysis for tin (Wood, 1958 and Ross and White, 1961) a means is available for rapid analysis of materials not susceptible to quantitative testing by hydraulic methods because of the fine sizings of cassiterite or the occurrence of tin structurally held in minerals. The new methods thus opened up the field of tin prospecting by extending the search for ore guides to genetically associated rocks and minerals, wall ror-ks of veins and a wider range of superficial deposits.

Jan 1, 1963

By Rowena C. Duckworth

The Ocean Drilling Program (ODP) is the largest international geoscience project in the world, and the state-of-the-art drill ship, the JOIDES Resolution, is permanently at sea. Each year there are six scientific cruises (legs) which each last approximately two months. These legs are designed by geoscientists from the nineteen countries that subscribe to ODP. Australia and Canada presently share ODP membership under the banner of the AUSCAN Consortium. The benefits of Australia's involvement in ODP include internationalisation of Australian geoscience, advanced graduate training, and unique scientific investigations of the ocean floors in the Australasian region. In addition, visits to Australian ports by the ODP drill ship, the JOIDES Resolution, contribute up to $2 million per visit to the local economy. Amongst the many other aspects of ten years of scientific drilling, ODP has significantly contributed to our understanding of hydrothermal processes on the seafloor. To date, three hydrothermal sites have been drilled to date by the ODP, Snakepit (MAR), Middle Valley (Juan de Fuca Ridge) and TAG (MAR). Two more hydrothermal sites are scheduled for 1996.

Jan 1, 1995

Regions with extensive reserves of brown coal but with inadequate deposits of hard coal provide a particularly suitable field for the application of brown coal petrology.In fact, this discipline is indispensable where brown coal is to form the basis for high-quality products of upgrading. Both chemical and physical analyses are required in addition to the techniques employed in coal petrology, but it is the macropetrographic and the microscopic investigations that are of decisive and specific importance.Foremost among the methods of upgrading brown coal is briquetting. From the raw materials aspect the biochemical rank of coal (i.e. the type of deposit) and the coal variety (i.e. the lithotype) exert a marked influence on briquette strength. These are also the significant factors in the suitability of a brown coal for high temperature carbonization; here the demands on coal quality are even more exacting if adequately sintered and therefore high-strength lump chars are to be obtained. The principle applies also to the char from low temperature carbonization. There are close relationships between the tar yield and the remission of the coal.The reflectivity measurement therefore provides a rapid method for evaluating the suitability of a brown coal for low temperature carbonization. Similar correlations have been established between the content of extraction bitumen (raw montan wax) and the remission. Petrological investigations show that the quality of the coal bitumen is a function of the type of deposit and of the lithotype.

Jan 1, 1968

By Madgwick J. C

A novel, microaerobic, heterotrophic microbial leaching system for manganese dioxide is described. Mixed natural microflora were enriched by addition of sugars and crude plant nutrItIOnal supplements. Between 84 and 104 mg MnH was solubilized per gram sugar at I per cent (w/v) concentrations for fructose and galactose in the presence of 0.03 per cent w/v dried microalgae (a Chlamydomonas species). Some 42 per cent soluble manganese was dissolved by microbial action on MnO, (3 per cent (w/v) pulp density) using a 10 per cent (w/v) molasses growth substrate.

Jan 1, 1983

During the drilling campaign conducted between October, 1942; and May, 1943, to prove the extent of the scheelite deposit worked by King Island Scheelite N.L. at Grassy, King Island, Tasmania, 35 holes were drilled and 606 samples recovered and assayed for their content. Of these, 238 came from outside the limits of the orebody and were for the most part barren, although a few contained some scheelite. The present statistical analysis is made only of the 368 samples taken from diamond-drill cores of the orebody itself.Drilling Pattern and Sampling MethodsFrom the purely statistical viewpoint, it is realised that methods employed in selecting sites for diamong.-drilling, and of collecting samples from drill cores, do not give a completely unbiassed set of data for analysis. Fig. 1 is a sketch plan showing the relativepositions of the drillholes, which were inclined at an angle of depression of 50 deg. The pattern does not conform to a properly randomized and' regularly-spaced grid, the positions of the later holes being determined by the results obtained from previous holes.Statistically, the bias is, therefore, favourable. The unequal spacing of the drill holes and the lack of uniformity in direction of the lines along which the holes were drilled are unsatisfactory from the mathematical viewpoint; but it is realised that these irregularitiesare difficult to avoid in determining by the most economical methods the extent of such an orebody, and are dictated by geological rather than mathematical necessity.Sampling, also, is lacking in complete uniformity. Each sample is approximately 10ft. in length. However, owing to the fact that 100% recovery of core is rarely achieved, and actual lengths of samples taken are ,primarily governed by the length of the drill runs,and secondarily by lithological changes, there is a considerable amount of variation in the sample length.AssayingWith the exception of 28 samples from three drill holes all samples dealt with in this paper were assayed in the Melbourne University Ore-Dressing Laboratory of the Commonwealth Scientific and Industrial Research Organisation. These assays were given to the nearest 0.05% WOg as it was considered that more accurate determination was not possible. This fact has been taken into consideration in the frequency analysis below. The 28 assays determined by the Tasmanian Mines Department were given to the nearest 0.01%.

Jan 1, 1950

Prefeasibility planning and cost estimation of conveyor systems has historically been undertaken by comparing fixed plant transport requirements to that of similar systems in service. This paper describes the development of a prefeasibility conveyor technical design and cost estimation application using Microsoft Excel Visual Basic for Applications (VBA) platform. The application tool known as D-Convey (Dachshund Convey) was developed with the goal enabling the end user:- to develop a technical model for conceptualised conveyor systems,- to perform economic analysis on the developed technical model, and - to conduct a comparative and risk analysis.An Excel VBA based platform was utilised to draw upon both the analytical and graphical capabilities of a spreadsheet. Some of the features of D-Convey system include a revolutionary dynamic graphical help system, known as the 'information pane' in lieu of traditional help files as well as the use of familiar graphical user interface elements such as the MS Office 2007 task ribbon. The D-Convey system incorporates material database allowing for mass handling prefeasibility estimation in other industries; it has been validated at a local quarry.

Dec 6, 2010

In understanding the consequence of existing law, and the likely implications of its reform, it is necessary to comprehend the logic of the situation that the law provides individual decision makers and how that situation would be adjusted by reform. In particular, the way in which natural resources, including minerals, are used and managed is influenced by the definition and structure of property rights that the law provides. Property rights are enforceable claims to use or to benefit from resources. An example is a mining licence that allows its holder to extract minerals in a specified area. Property rights establish the structure of incentives, opportunities and constraints within which resource use decisions are made, ie the logic of the situation, and hence influence the use and management of resources. The extent and type of mining in New Zealand, for example, reflects the rights that miners have to extract minerals, and their rights to benefit from mining as against their duties to compensate landowners and pay royalties. This paper describes the characteristics of minerals that are relevant to the definition of property rights, analyses the implications of alternative property right arrangements and describes the existing situation.

Jan 1, 1988