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By E Widijanto, A Srikant

PT Freeport Indonesia operates a copper-gold mine located in the remote highlands of Papua, Indonesia, about 3500 km east of Jakarta. Currently, the district produces about 240 000 tonnes per day (tpd) of which about 45 000 tpd come from the DOZ Block Cave and the rest is mined from the Grasberg Open Pit. Over the next ten years, ore production from large block caves in the area is expected to reach about 200 000 tpd, replacing a large part of the production from the Grasberg Pit. Block cave mining alters the hydrological characteristics of the area being mined and when the cave expresses itself at the surface in the form of subsidence, it increases the entrapment area for surface water. Operating a large block cave mine in a region with an average annual rainfall of 5500 mm in steep mountainous terrain and complex geological and hydrological features presents a challenging scenario for dewatering or depressurisation of the area. The high rainfall infiltration and entrapment in stacked mines operating within an essentially single orebody, coupled with the presence of fine-grained and clayey material within the draw points of the block cave, creates mud rushes or wet muck spills, which can endanger the personnel and interrupt production. This paper outlines the problems caused by high water inflow into the DOZ Block Cave and the efforts undertaken to ensure the safety of the miners and continued achievement of desired production rates from underground mining in the district.

Jan 1, 2006

Laboratory high tension roll separation and the commercial machines available for this purpose are discussed. The shortcomings of these machines are indicated and a machine that overcomes some of these undesirable character- istics is described. A procedure for evaluating laboratory high tension roll separation is described. The use of this evaluation procedure in conjunction with the laboratory separation is described with examples taken from the Dunwich and Hexham processing plants of Associated Minerals Consolidated Limited. Evidence that laboratory testwork results may be directly transposed to operating plants is given. A discussion of the effects of variables in high tension roll separation of mineral sand concentrates concludes the paper, and uses in support results obtained in the metallurgical laboratories of Associated Minerals Consolidated Limited, Southport, Queensland.

Jan 1, 1972

The paper presents an overview of the mining industry of Papua New Guinea. Although the Bougainville problem is still unresolved, new mines like Ok Tedi, Misima and Porgera, which have come on stream during recent past, have raised hopes of sustained growth period in the industry. Kutubu Oilfield is also being developed in the Southern Highlands and the oil production has commenced from July 1992. Government revenue from these mega projects will increase five-fold during 1993 and 1994. A new mine which is being planned is the fabulous Lihir Deposit, on an island renowned to be full of gold. Gold occurs within a volcano which still contains high temperature ground water because the system which created the deposit is still geothermally active.In Papua New Guinea, problems of environmental management are far easier to tackle than those of a socio-political and economic nature involving compensation payments to the landowners and the distribution of royalties and taxes between the national and provincial governments. At the socio-political level, the country has not been able to resolve the problems of land rights versus mining rights. Whenever mining starts in a big way, it raises people's expectations to a very high level, which then becomes the focal point of dispute between landowners, provincial governments, national government and mining companies. A new system called 'Forum' has been tried to bring all parties together and son out the issues. The system appears to be working well in new mines like Ok Icdi, Porgera, Misima and Kutubu Oilfields.

Jan 1, 1993

By Borshoff J, Coles R

The Rum Jungle Uranium Province is lo cated on the western margin of the Pine Creek Geosyncline approximately 60km south of Darwin. Uranium was discovered in the Embayment area (Whites Deposit) in 1949, spurring active ex- ploration and leading to the discovery of the Rum Jungle Creek South Deposit in 1959. With the discovery of the Alligator Rivers Uranium Field, new criteria in the understanding of the controls for mineralization sparked a re- surgence of exploration activities in the Rum Jungle area. Uranerz Australia Pty. Ltd. (UAL) commenced exploration in the area in the late 1970's in joint venture and in its own right. Two domal Archaean granitic complexes, the Rum Jungle and Waterhouse Complexes, domi- nate the area. They are unconformably mantled by Lower Proterozoic sediments metamorphosed to middle to upper greenschist grade. The Lower Proterozoic sediments are unconformably over- lain by remnant blocks of Carpentarian sand- stone, generally preserved in downfaulted blocks. Over a six year period extensive geolo- gical, geochemical and geophysical programs were conducted to reinvestigate previous target areas and locate new prospective zones. Exten- sive shallow bedrock drilling showed that lo- cally the stratigraphic succession is quite variable and cannot always be divided into an ordered succession for correlation with groups and formations established by the Bureau of Mineral Resources (BMR). Deformational events resulting in intraformational recumbent folding and overthrusting also account for repetition of certain lithotypes.

Jan 1, 1984

By M R. Asef

Although generation of environmentally harmful hydrogen sulfide is considered to be related to sour gas fields, sweet gas reservoirs and waste fluids, travertine springs and geothermal fields may also produce acid gas (H2S and CO2) under certain conditions. The potential parameters influencing such a possibility need to be fully investigated to evaluate the extent of the consequences and predict hydrogen sulfide generation accordingly. Reports on hydrogen sulfide production at different regions and fields were gathered worldwide for the cases when some of them did not have such a problem previously. In order to inspect different aspects of these case studies, some other regions with no hydrogen sulfide content were selected as control. In all cases water samples were taken carefully for chemical analysis in the laboratory. Besides, mineral compositions were characterised in some cases for better evaluation. In order to give a thorough prospect of hydrogen sulfide production, a geochemical model was prepared. In situ engineering geological conditions, especially pressure and temperature, were assigned in the model to investigate the possibility of H2S generation using PHREEQC software. The results of modelling revealed that although many similarities existed between mineral compositions of the cases, certain formations were particularly prone to hydrogen sulfide generation. For better evaluation, important exchangeable cation ratios such as potassium/sodium, calcium/magnesium and ion proportions like sulfate and chloride were calculated as trends of the formations. As expected, the model could successfully monitor a higher ratio of SO42- and Cl- in potential H2S generator formations. Wide variation in percentage of HCO3- was considered as a secondary observatory parameter for better estimation. In addition, it was noticed that higher anion content created an environment ready to absorb any cations and this makes H2S generation easier. Finally, using correlations between predictors and estimators for low depth and deep samples defined the degree of effectiveness for every sample.

Sep 26, 2011

By Cocker A

Pre-splitting for smooth highwall formation is conducted in around 75 per cent of surface coal operations within Australia. The CMTE (Centre for Mining Technology and Equipment) in conjunction with BHPAC (BHP Australia Coal) initiated a project to look at pre-splitting and to investigate the notching of blastholes for fracture plane control. The notching was specifically for pre-split initiation and also for discing of the toe of the production holes to minimise coal loss from the top of the coal seam. There are currently a number of factors which are driving the introduction of new pre-splitting technologies and products. The first is the ever increasing bench height being employed in strip mines which require a higher quality wall with less blast damage to maintain stability. Currently depths of 55 metres are common place with depths of 70 - 80 metres fast approaching. The second factor is the introduction of new technologies or methods which require a high quality highwall produced, eg highwall mining. This paper discusses the current state-of-the-art in pre-splitting and the main issues facing successful pre-splitting in the future. The use of a blasthole notching technology to promote fracturing along the pre-split line is also analysed. The review indicates that most pre-splitting challenges in the future can be addressed through better use and developments of current drill and blast technology. It is also concluded that a blasthole notching technique may find niche applications in improving final walls within a surface coal mine, especially where a high quality wall is required. The notched blasthole method may also allow pre-splitting in ground conditions and adverse rock structure which currently cannot be pre-split by existing technology.

Jan 1, 1995

By Smith J. W, Wilkins R. W T

This paper is a preliminary report of research on the Mount Morgan gold-copper deposit being done at the Division of Mineralogy, CSIRO. Fluid inclusion and sulphur isotope measurements were made on a suite of 11 samples collected by the staff of Geopeko Ltd. This suite contained representatives of the main ore and rock types of the deposit. Homogenization temperatures of fluid inclusions measured on quartz from 8 of the 11 samples, ranged from 172¦C to 276¦C and to this must be added a pressure correction (in this case, up to 50¦C) to obtain the formation temperature of the mineral. Sulphur isotope measurements were made on 34 sulphides from 8 of the 11 samples. The 6S values form a well defined group ranging from -0.5%oto +3.6%owith a mean of +2.4%c. Although the preliminary data do not indicate unequivocally the origin of the deposit they do impose restraints on the wide ranging suggestions that have been put forward. This work is complementary to the paper of Dr G. Gibbons who has described other mineralogical aspects of the Mount Morgan deposit, based on a more extensive suite of Samples.

Jan 1, 1974

By M Norbert, P Mok

The mainline running tunnels for Legacy Way comprise of two-lane tunnel boring machines (TBM) driven tunnels. The length of the TBM tunnel section is approximately 4.2 km. The TBMs employed are double shield TBMs. Typical support to the segment ring while advancing a double shield TBM comprises of filling the excavated annulus between the ground and the segmental lining by injecting pea gravel, followed with primary grouting to fill between the pea gravel some distance behind the excavated face. The methodology adopted for the Legacy Way project, however, did not follow this typical approach, instead, two component grouting of the annulus was carried out.Where the annulus is typically filled with pea gravel, support is provided to the segment ring very close to the end of the tail shield, whereas in the case of two component grout this is not practical as the risk of grouting in the tail shield is high. The staging of the two component grout injection, the grout early age strength properties become key issues in ensuring that the segment ring leaving the TBM tail shield is stable and can support the necessary external loads.Two-component grout is a grout with two components, cementitious grout (component A) and accelerator (component B), commonly adopted for earth pressure balance (EPB) TBM. The grout reaches its thixotropic state in a matter of seconds providing initial support for the segment rings. Manual injection of two component grout to fill the bore annulus was carried out in stages leaving a portion of the segment rings unsupported. Ring stability during TBM advance was provided by a combination of ram thrust and the segment circumferential joint shear connectors.This paper outlines the design considerations such as rock load derivation by probabilistic analysis carried out utilising the software JBlock, 3D finite element analyses using the software Strand7 for ring stability and the testing and back analysis of the shear connector load bearing behaviour. In particular, the actual available capacity of the shear connectors against their published capacity by supplier was discussed.CITATION:Mok, P and Norbert, M, 2014. Tunnel boring machine excavation stability – double shield tunnel boring machine advance with partially grouted annulus, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 51–62 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By Thompson IR, Solomons SS

Underground mining with the cut and fill method has been declining during the past decade or so, being replaced mostly by sublevel open stoping methods. During 1983 the Australian Mineral Industries Research Association Ltd. (AMIRA) commissioned a review of the method, with the aim of compiling the state-of-the-art, indicating future trends and recommending topics for research that would be needed to support this future mining. Mines using the cut and fill method in Australia and three other countries were visited to compile current practices and expected developments.Cut and fill is mostly used where geological and ground conditions are unsuitable for open or caving methods. These range from narrow, irregular orebodies to wide, massive orebodies where pillars are retained in ore. There is significant potential for improvement and further development of the method. It may then be used in a broader range of conditions and for orebodies that may not otherwise be viable to mine.

Jan 1, 1985

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

By J Howard

Following discovery in October 2004, commencement of development in February 2007 and first ore production in mid 2007, the Trident gold deposit, located in the Eastern Goldfields of Western Australia, has now been successfully mined for over three years. Three years of operational history has enabled the performance of the Trident underground mine to be reconciled against the mine plan and strategy proposed for the original feasibility study.The Trident deposit, initially based on two lode systems known as the Eastern Zone and Western Zone, has been continuously drilled, interpreted and re-interpreted over the period and as a result the addition of the Athena, Apollo and Artemis lode systems as well as numerous smaller scale lodes has been realised. The first three years has seen the Trident underground mine quickly move up to its 1 Mtpa design production rate. The mine plan and strategy used in the initial feasibility study and subsequently implemented, required sufficient flexibility to enable modification and optimisation to mine plans as ore zones were further defined. The ability to modify the mining plans has enabled Avoca to achieve its mining targets at Trident. With over 250 000 ounces gold produced to January 2010, the company is well positioned to achieve its ten year vision associated with the Higginsville Gold Project.This paper offers an account of operational experiences whilst providing comparison to assumptions and methodologies used in the original feasibility study. The paper is a sequel to a paper presented at the Tenth Underground Operators’ Conference held in Launceston, Tasmania titled Development Strategy of the Trident Underground Gold Mine.

Mar 21, 2011

Bakelite is fairly widely known as a suitable material for the mounting of ore specimens, concentrates and tailings for microscopical study, but has not as yet had extensive application. It is the most suitable mount for specimens which are to be held in the mechanical holder of a polishing machine, based on that described by J. W. Vanderbilt*, which is installed in the Geological Department of the Melbourne University.Bakelite products are prepared by subjecting bakelite powder to a temperature of about 1600 C. under a pressure of approximately two tons per square inch for a period of four minutes. The shape and size of the products are governed by the use of suitably constructed dies. When the concentrate or tailing is mixed with the bakelite powder, a briquette is produced which can be polished so that the opaque minerals in the sample can be examined microscopically in the same way as in a piece of solid ore. A simple machine for the construction of these briquettes has been described by Head and Slavin. It consists of a small four-pillar press in which the pressure is supplied by...

Jan 1, 1933

By Falconer A. J

Two magnetic parameters are proposed as a basis for the assessment of ironsands beneficiation. The parameters are deter- mined for raw sand prior to dredging and for magnetic separator head feed over a production period of five months. The relationships between these parameters and the performance of the magnetic separators are examined to establish the value of magnetic assessment compared with the traditional soluble iron assay method. The results illustrate that the first parameter, true magnetic fraction (TMF), has a value superior to that of soluble iron when relating raw sand grade calculated by tri- angulation to magnet performance. In terms of the relationship between magnet head feed grade and magnet performance, TMF and soluble iron perform equally as assessment parameters. For the ironsands mined during the five month period, the second magnetic assessment parameter, composite fraction (CR), is shown to merely reflect TMF and offers no additional information for assess- Ment. Conclusions are that true magnetic fraction has many advantages over soluble iron in terms of time and cost of determination and that it is a meaningful and reliable parameter upon which to base all calculations relating to the mining and beneficiation of ironsands.

Jan 1, 1980

Longwall mining in Australia is approaching maturity. Longwall production from 'state of the art' Australian longwall mines now rivals similar US based longwall operations. Regrettably however, Australian gate road development rates in general fall short of the required development to longwall production ratios that are required to sustain annual longwall production capabilities. By contrast, most US based longwall mines achieve the required development to longwall production ratios to sustain their longwalls. This is despite many having to drive three heading longwall panel gate headings to meet regulatory requirements.

Jan 1, 1998

The introduction of large diameter holes to underground mining has provided the first opportunity to apply near spherical charges in production scale blasts instead of the convent- ional long cylindrical charges generally used in stope and pillar mining. A modified version of the cratering prin- ciple was applied in the blast design in extrac- ting ore across a horizontal area of a stope or pillar. The new rock breaking technique has developed into the Vertical Crater Retreat (VCR) mining system and eliminated raise boring, slot cutting and dilution of the ore by back- fill material. Furthermore it has reduced labour and time requirements thus becoming not only a low cost method of mining but the safest method of underground mining known today. Exceptionally fine muck is provided with a minimum of damage by blasts to walls and re- treating backs of the stope or pillar. The VCR method can also be used for drop- raising, and for the excavation of underground cavities for almost any purpose . The proper explanation of the breakage mechanism of the near spherical charges opposite to the cylindrical charges yet to be found. The mining industry has quickly recognis- ed the value of the VCR mining method which is being adopted by an increasing number of mines

Jan 1, 1978

The Hunter Valley Rail Project (HVRP) represents most of the coal producers using the Hunter Valley Rail System in NSW to haul coal to the port of Newcastle. This system carries over 70 per cent of NSW's coal exports, comprising over 30 per cent of total Australian coal exports. Hunter Valley coal is the largest export industry in NSW, and one of its largest export growth opportunities. However, the industry is under intense pressure in international markets from existing and new coal producers and from other energy sources. Whilst potential growth in demand is substantial, particularly for thermal coal in Asia, excess world supply has pushed prices down, and this underlying trend may well continue. The industry has lost international competitiveness and as a result, investment has dropped 44 per cent over the last two years. The industry must be rapidly structured to compete and attract investment on the basis that these pressures will continue. Substantial productivity improvement and cost reductions must be made for the industry to regain competitiveness, otherwise growth will not occur and the industry will decline, with serious implications for the Australian and NSW communities. The introduction of internationally competitive rail freight rates is an urgent and essential part of this process. It is the key objective of the HVRP.

Jan 1, 1995

By Schonert K

The throughput of a HP-roller mill is determined by the acceleration of the feed material within acceleration zone and introduction into the compression zone. Both processes depend on the internal friction and the friction of the material on the roller surface which is influenced by the surface structure and adhering of material. The particle motion in the acceleration zone has been investigated with high speed videos showing the effect of the centrifugal force and the slip on the roller surface. The throughput is discussed in the term of the specific throughput which can be approximated by a linear function characterised by the throughput number and the throughput elasticity. The throughput number is a helpful measure for investigating the influence of the feed material and the surface structure. The experimental results give some guidance for chosing an optimum corrugation profile.

Jan 1, 1993

By Leach B. G

A geostatistical study was made of diamond drill hole intersections within 18CC stope block at the C.S.A. Mine, Cobar, N.S.W. The stope block is located in 18CC orebody which is a massive sulphide - multiple vein, Copper-Zinc type, lacking clear definition on gangue mineralogy, base-metal assays and total sulphide considerations. Of the variograms constructed for inter- section width and copper, lead and zinc grades and accumulations, only zinc displayed behaviour amenable to model fitting and kriging procedures. Zinc grades were calcu- lated for sub-blocks comprising the total stope block and comparison with equivalent grades determined by traditional methods showed them to be generally less extreme in the highest and lowest grade sub-blocks. The total-block grades derived by the two methods were almost the same. It is suggested that the failure of copper to show variogram continuity might reflect the difficulty in defining the actual 18CC orebody, a proposition which is supported by the poor continuity in the variogram of horizontal width. In the case of lead the poor continuity may be due to the frequent manner of occurrence of galena as coarse grained patches of limited extent. The results of the study, did not provide a convincing reason to depart from the traditi- onal methods of grade estimation at the C.S.A. Mine.

Jan 1, 1979

By C Armstrong, B Wentzinger

Upstream embankment raises often represent the lowest cost option for increasing the capacity of tailings storage facilities (TSF), but also pose the highest stability risk due to constructing on top of previously deposited tailings.This paper presents an overview of key aspects in the geotechnical investigation and design of upstream raises and some recent lessons learnt from experience across a number of TSFs in Australia. A summary of recommended field investigation and laboratory testing methods is provided with a focus on collecting quality information for design purposes. A strong focus is given in developing an accurate assessment of pore water pressures, which, if not correctly understood can have disastrous consequences on tailings strength parameter interpretation and wall stability assessment in static and post-seismic conditions.The assessment of the contractive or dilative shearing behaviour of the tailings material and rigorous interpretation of design characteristic values are presented. Some comments on stability analysis options and proposed methodology are also provided.CITATION:Wentzinger, B and Armstrong, C, 2018. Lessons learnt in geotechnical investigation and stability analysis for upstream tailings storage facility raise design, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 333–348 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

Before presentIng my address I wish to acknowledge the honour which has been conferred on me by my appointment to the position of President of the Australasian Institute of Mining and Metallurgy.It is a matter of great concern to us all to find our Empire at war. I am confident that, as was the case in the war of 1914-1918, members of this Institute and of kindred Institutes and Associations will contribute in full to the Empire's needs and that in the end our cause shall triumph.I think it appropriate that I should take as the subject of my address that of the Broken Hill Lead-Silver-Zinc Industry. The subject matter of this address has been confined to the operations of Mining, Ore Dressing, Lead Smelting and Refining and production of Electrolytic Zinc in Australasia. The review of the Broken Hill Lead-SilverZinc Industry would not, of course, be complete without reference to those Australian industries which trace their origin to the Broken Hill field, but· it is thought that an outline of these industries would make thIs review too extensive.HISTORICALMany efforts have been made to translate the early history of Broken Hill and its subsequent growth throughout the years into one of the wor~d's most famous mining fields in the form of a simple story.

Jan 1, 1940