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A model of dense medium cyclones is developed based on balancing the terminal velocities of the discrete particles due to the centrifugal force against a random turbulent eddy velocity. An expression of the form P - or Q _ 1 100 e."A where P is the partition number., is a function of cyclone efficiency, particle size and density differential between the particle and medium, and is the slurry spilt, is developed and may be used for regressing plant partition data. The above model provides an understanding of peculiarities of the partition curve such as asymmetrical tails, elevation of the cutpoint and elevation of the d50 with increasingly fine feed. The effect of feed variables such as particle size, medium viscosity and changes in spigot or vortex finder diameter is shown. A means of convoluting the partition curve with various feed washabilities is discussed together with how the above may be used to evaluate plant performance for a variety of feeds.

Jan 1, 1987

Drilling and blasting operations have historically been viewed as a necessary 'evil' part of mining, whose costs should be minimised by whatever means possible. In the past, when operations depended primarily on crushing and milling for ore re

Jan 1, 1998

By Paley N, Cameron A, Townson P

Although blasthole deviation is a problem which can seriously affect blasting operations, there is little practical emphasis on controlling this deviation and no practical emphasis on understanding its practical behaviour. The most common way of dealing with it involves tight control over drill set up and surveying hole paths. The surveying might involve simple collar location and inclination measurement to estimate the hole's actual path. At best, some operations routinely survey hole paths after all holes in a stope have been drilled. In addition, although there is an expectation that holes will deviate, there is no planning for this behaviour in order to reduce its impact on the blast. Design decisions are invariably made with the assumption that holes are straight. If and when surveys reveal problems it is possible only to adjust charging and initiation to 'work around them'. In extreme cases the drill might be recalled to fill in gaps. The lack of planning and the lack of understanding are doubtlessly linked.A model is presented that will predict the expected path of a drill hole. By knowing how a selected few holes deviated it is possible to make a good estimate of the deviation of other holes in the same rock mass. After minimal calibration the model can be used to increase the amount of information for a given amount of surveying or the amount of surveying can be reduced while maintaining the same level of knowledge of blasthole deviation. Equally important is the ability to plan for the deviation in future drilling through altering the initial collar angles or drilling from different locations. It is the authors' hope that planning for hole deviation becomes as much a part of the design process as planning for detonator delay scatter and explosive performance variation.

Jan 1, 1992

By Morrell S

As more and more autogenous and semi-autogenous mills are run in closed circuit with cyclones the limitations that can be imposed by poor grate and pulp lifter design are becoming increasingly apparent. Relevant literature on the subject is al

Jan 1, 1997

By Conochie DS

SIROSMELT is a successful new pyrometallurgi- cal furnace system using a top-entry lance which can be submerged in both slag and matte. The lance is of simple construction, and is cooled by process air. Pilot plant work commenced in the CSIRO Division of Chemical Engineering in 1972 using a 50 kg batch reactor. This paper traces the development of the technology through various slag cleaning and smelting processes up to a scale of 5 tonnes per hour continuous feed. Strong co- operation between CSIRO and the Australian smelting industry has contributed greatly to the success of SIROSMELT.

Jan 1, 1984

By I Jabou, D G. Blazak, L C. S Hogarth

The R70 test is a good indicator of coal reactivity to oxygen and is commonly used to provide a rating of propensity for self-heating. Tests performed by The University of Queensland Spontaneous Combustion Testing Laboratory have resulted in the development of a large database that shows the impact of coal quality on this parameter. From these results it is possible to infer an R70 value, which can be used to gain an appreciation of the intrinsic coal reactivity before it is even tested. However, any interpretation of R70 values must consider the influences of coal rank, mineral matter and moisture content to provide a better understanding of the spontaneous combustion risk of a particular coal.

Jan 1, 2005

By Stevenson BG

The relevance of ore-dressing mineralogical investigations to developing and improving metallurgical flow-sheets is discussed and examples are given of the application of such studies to various types of ores and mill products (Au, Cu-Sn, Ni and Sn). The mineralogical investigations described illustrate (a) assessment of the feasibility of ore pre-concentration by heavy-media cyclone separation, (b) evaluation of the potential applicability of various metallurgical treatment processes to an ore, and (c) characterization of mill products to assess circuit efficiency and to guide circuit modifications.

Jan 1, 1978

By Barnes R. G, Agostini A, Lewis P. C

The Mineral Resources Audit is a five-year Program established to produce a comprehensive and objective assessment of the mineral resources of New South Wales, including prospective resources. The goals of the Program are to improve planning and land use decision-making; attract exploration and minerals related investment; help the Department to identify and fill gaps in knowledge; and develop methods to identify and quantify resource potential and prospectivity. To achieve the goals of the Audit it is necessary to assemble and enhance a large amount of information and it is necessary to spatially analyse this information using computer-based Geographic Information Systems (GIS) which allow the collection, storage, transformation and display of large quantities of spatial data. An extensive range of both map-based and textual data can be employed in spatial analysis and resources and geoscience modelling. In order to use this information, data sets have to be corrected and standardised. Many data sets need to be classified. An objective of the Audit Program is the spatial analysis of the State, region-by-region, and the release of cleaned-up multiple digital data sets as packages which include upgraded mineral deposit information, 'seamless' geological map layers showing lithology, structures and stratigraphy, and processed and classified geophysical map layers. These regional packages are important reference sets for the mineral resources industry and will assist delineation of regional exploration targets.

Jan 1, 1995

Different mineral structures can act as mineral reservoirs for the immobilisation of toxic compounds. In the paper different mineral structures will be explained and their potential for incorporation of heavy metals and anions will be shown. The following structures will be explained (P÷llmann, 2007):apatites (incorporation of heavy metals, silicate apatites);ettringites (fixation of oxo-anions);layered double hydroxides (fixation of heavy metals, fixation of anions, fixation of organics, sorption materials); andmanganese oxides. Different possibilities of solid solution and incorporation in crystal structures will be explained and advantages of stable minerals be proved using experiences with real toxic wastes. In the process of thermal treatment the formation of primary mineral reservoirs will be shown. The precursor phases (similar to well known cement minerals) react in contact with water to form secondary mineral reservoirs (cement hydration mineral products). The formation condition of primary and secondary mineral reservoirs and their stabilities and incorporation possibilities will be shown. Examples for incorporation of various elements are given. Application for water clarification will be outlined.

Jan 1, 2008

By Guo H

The importance of using disc cutters for rock excavation is reflected by their wide application in hard rock cutting machines such as tunnel boring machines and raise borers. The forces involved in the cutting process are those due mainly to thrust and rolling forces and are greater than that required by cutting picks. An interesting feature of cutting with discs is the formation of surface crushing, surface and sub-surface chipping and primary crack formation. Experimental, as well as analytical, work has been carried out to determine the optimum spacing between the disc cutters to control primary crack orientation. Wedge bit indenters were used to simulate disc cutters. The paper concludes by proposing a new approach to rock excavation by hybrid cutting based on controlling the primary crack Orientation.

Jan 1, 1992

The mining. operations of Bougainville Copper Pty Limited are located at Panguna on the Island of Bougainville which is part of the Territory of Papua and New Guinea. Mineralisation in the Panguna area was first established by C.R.A. Exploration Pty Ltd in 1964. Exploration work since then has established ore reserves estimated to be 760,000,000 tons of.0.47% copper and 0.4 dwt./ton gold. An economic feasibility study completed in July of this year has enabled a decision to be made to proceed with a major mining operation. The ore will be mined by open cut methods and will be treated in a conventional concentrator with a nominal capacity of 90,000 short tons per day. The concentrate will be pumped as a slurry through a 15 mile long pipeline to a port established on the east coast where it will be filtered and dried ready for export. Other supporting facilities for the mine include two towns, a 135 megawatt steam power station, and access roads.

Jan 1, 1970

By Bhattacherjee A, Makesh S

Mechanised sub-level stoping is one of the most widely accepted stoping practices followed in base metal mines in India. As a general practice, blast-scheduling of rings in these stopes is done either heuristically or randomly which leads to a high fluctuation in ore grade when drawn and delivered to the mill. In this paper, dynamic programming has been investigated as an optimisation technique for optimal blast-scheduling of rings. A microcomputer based dynamic programming algorithm has been developed in C language which runs under the UNIX environment. A case study based on Indian mine data is presented to demonstrate the application of the dynamic programming concept and use of the developed software. It is concluded that dynamic programming can be used as a production planning tool in Indian mines practicing sub-level stoping and following heuristic/random approaches for blast-scheduling of rings.

Jan 1, 1995

By R Billingham

QueenslandÆs new safety legislation for metalliferous and coal mining (Mining and Quarrying Safety and Health Act 1999 and Coal Mining Safety and Health Act 1999, together with the Regulations) came into effect on 16 March 2001. The legislation places clear obligations on mine owners, operators and workers to have a safe place of work and to manage risks to safety and health. It also places obligations on contractors, designers and providers of services. The legislation is non-prescriptive in that it states what outcomes must be achieved and not what must be done. The key issue is that the risk of injury to people must be at an acceptable level. The legislation creates a Mines Inspectorate with powers of inspection and audit of mines, their safety management systems and the management of risks. Auditing of the risk management process is carried out against standard risk management techniques and directives for corrective action may be issued when audits reveal non-compliance or unacceptable levels of risk.

Jan 1, 2002

Robertson Diasol have developed a spectral gamma-gamma tool fully able to withstand borehole conditions. Spectral data is digitally recorded across 256 channels depending on energy levels of the photoelectric effect. Data processing is being developed with the objective of calibrating channel amplitudes to mineral type which will lead to a direct log of selected mineral grade as a continuous trace with depth.

Jan 1, 1990

By Kleine T. H

Blast design involves many engineering constraints and objectives. Some of the more important include the implementation costs, the desired fragmentation and shape of the muckpile. A spreadsheet has been developed to allow blast design options such as burden, spacing, blast hole diameter, decking and explosive type to be varied. As any option is varied the spreadsheet recalculates and graphs the expected implementation costs, fragmentation and muckpile shape in seconds.The spreadsheet extends the philosophy of simple robust fragmentation prediction (Cunningham, 1983) to include similar models for explosive detonation (with respect to explosive type, age, blast hole diameter and density) and muckpile shape (with respect to burden, spacing, charge location and weight). The new empirical models for explosive detonation and muckpile shape prediction have been calibrated successfully for one situation and are now undergoing further field trials.

Jan 1, 1992

By Kelly E. G

New Zealand suffers the disadvantage of widely scattered ore bodies, none of which is large enough to economically support its own smelter. This leads to the concept of a centrally located smelter which must be flexible enough to cope with var

Jan 1, 1980

By Tuite M. J, Woolcock L. J

The Awak Mas gold project is located in the Province of South Sulawesi, Republic of Indonesia. It is situated 300 km by road north of the provincial capital of Ujung Pandang. The capital is readily accessible by air from Australia via Denpasar on Bali or the Indonesian capital, Jakarta (Figure 1). Elevations at Awak Mas range from 850 to 1400 metres above sea level in reasonably rugged terrain. The area is covered by primary and secondary (regrowth) rain forest. The region is subject to an equatorial-type tropical climate. The annual rainfall is a high 3000 mm most of which falls in the rainy season between March and June. In the lower valleys rice, cloves and chocolate crops are cultivated. Title to the project area is secured by a Contract of Work (COW) issued to PT Masmindo Eka Sakti (MES) on 23 October 1987 by the Government of Indonesia. MES was controlled at the time by New Hope Industries group of Brisbane. After New Hope had completed initial reconnaissance exploration of the area, Battle Mountain Gold Company (BMGC) farmed-in in 1991 and earned a 60 per cent beneficial interest in MES.

Jan 1, 1996

By A Robertson

Australia has been slow in adopting the use of underground space as a part of our urban planning process. Australia has one of the highest levels of tunnel advance per capita per annum in the world, yet the use of underground space in our cities appears difficult for our planners and politicians to comprehend, not withstanding the general availability of good quality rock and contractor expertise in Australia. However, the lack of space in our urban areas is being highlighted as our major cities expand outwards and people and businesses gravitate towards city centres. Typical potential underground space uses include car parking, self-storage and archiving facilities, water storage, underground quarrying, small industrial facilities and another layer of traffic (electric and fuel cell) and services network. Historically, blasting in high density population areas has resulted in blast vibrations and blast overpressures exceeding the limits, which in some case have been set extremely low in terms of peak particle velocity (PPV). This makes conventional blasting difficult, often requiring low charge weights per delay and associated small blast sizes and slow advance rates. However, the introduction of new technologies, such as computer aided drilling, electronic delays and low-energy explosives has made this task considerably easier. Although more expensive than conventional blasting, excavation by blasting using these products and technologies in relatively good quality ground is believed, in most cases, to be less than the cost of mechanical excavation. In this paper, the authors look at innovative trends in underground quarrying, underground commercial space and tunnelling and put forward their concept of future excavation demand, future product requirements and technical specifications to the drill and blast community.

Jan 1, 2007

By Storey AG

Following initial plant scale work on the development and performance of 'spray' oil lances, a full scale room temperature model of the blowpipe-tuyere region of a blast furnace was built to study the basic aerodynamic features of auxiliary fuel injection procedures. Mobilwax 2305 was used as a substitute for Bunker C oil fuel in view of its similar physical properties and the fact that the atomised droplets could be frozen in flight and size, distribution analyses made for various operating procedures. It was shown that secondary atomisation processes far outweighed the importance of any primary atomisation procedures in determining mean Sauter Diameters particularly at high windrates typical of current blast furnace technology. It was also found that good spray dispersions across the blow pipe could only be obtaind for liquid fuels and that the lateral rate of spray dispersion was substantially enhanced by primary atomisation procedures. Mean particle diameters of sprays were found to be predictable on the basis of elementary stability theory and fell within the size range necessary for good combustion at all liquid fuel rates studied. The possible effects of high oil injection rates on flooding phenomena in the furnace bosh were considered. Comparisons show that high oil rates can lead to significant increases in the hanging factor (e.g. 'V 10% at 135 kg oil/thm) owing to increased gas flow rates/thm resulting from the presence of hydrogen.

Jan 1, 1975

The need to estimate the block size distribution of a jointed rock mass is of great importance in the design of blasting rounds to attain a pre- established fragmentation. Other Geomechanics topics, such as ,hydraulic behavior of rock-masses, as well as the determination of their strength properties, also require the accurate prediction of a rock-mass composition in terms of block size taking in due account the three dimensional interference of joints and other geologic discontinuities. In this paper, a method for computing the block size analysis of a jointed rock mass is described, using as input the common geologic data (dip and strike) of fracture planes existing in a rock bench prior to blasting.

Jan 1, 1977