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By Fabjanczyk M. W

The design of underground mine roadways (tunnels) requires a detailed understanding of the in situ stressfield, the rock failure modes, the performance characteristics of reinforcement or support members and assessment of the stress state about the roadway. Definition of these factors, together with monitoring of roadway behaviour during both development and extraction operations, allows rational design procedures to be undertaken.The design approach utilised computational techniques to simulate the behaviour of the strata about the opening for a range of anticipated stressfields and various reinforcement options. Field validation studies are conducted to confirm the design expectations.

Jan 1, 1993

Railway cuttings require the highest care in design and construction, as the pro- bability of failure concept does not allow any risks to be taken with hundreds of lives being dependent on continued stability. The usual geological influences on stability such as bedding dip and faulting are often discus- sed, but other major problems may come from the presence of sheet joints, cross joints differential weathering and seasonal or daily changes of ground water level. The design of rail cuttings has taken little note of the problems imposed by cons- truction methods, and low cost quarrying methods may seriously weaken a designed shape. The presence of berms and drainage ditches is often difficult to achieve as blasting imposes cumulative stresses and jointing on rocks. Contractors face difficulties in bidding extensive rock cuttings as variations in rock properties are often concealed and overshoot- ing the toe of a batter can easily occur. Modern blasting methods offer some solutions, but the best guide to safe successful cuttings is extensive investigation and the continued involvement of engineering geology at the stages of feasibility, design, construction and maintenance. Two case histories show the influence of folding, faulting and construction methods in the case of slope failure and slope stability.

Jan 1, 1979

Incidental to the progress of a geological survey of the Kalgoorlie goldfield during 1927-28 a number of specimens of telluride minerals were obtained, chiefly with the help of Mr. F. G. Brinsden, general manager of the South Kalgurli mine, and Mr. Ernest Williams, general manager of the Boulder Perseverance mine. This collection was supplemented by a number of small specimens, including the rare copper telluride, which were collected and preseryed from the Kalgurli mine by Mr. A. E. Paton, and also by a few miscellaneous specimens from the collection o{ Mr. S. F. C. Cook, of the Palace Hotel, Kalgoorlie.An extensive knowledge of the rare tellurium-bearing minerals was compiled during the last century from occurrences in Transylvania and Colorado. The recognition of different species has been based on chemical analyses and crystallographic measurements. In a few species there has been an absence of crystalline form, and these, together with the discoveries in this century of rickardite and "weissite" muthmannite and empressite, have depended chiefly on the chemical analysis for identification. On the other hand, the crystalline form of nagyagite and stiitzite has been described in detail, while their precise chemical formulae were doubtfully defined.

Jan 1, 1931

By Armstrong M

The highest grades of the Porgera gold deposit, Papua New Guinea, are contained in Zone 7 due to the presence of the Roamane fault, which acted as channelway of the gold-bearing fluids. Prior to the development and underground mining of this fault-controlled high-grade zone it was critical to provide grade estimates of relatively small mining units, and of the proportion of mining units above cutoff. To be applicable to Zone 7 of Porgera a grade estimation method should account for the following:1. the highly skewed and apparently lognormal distribution of the grades,2. the rapid drop off of the local mean grade and the variance as the distance to the Roamane fault increases,3. the presence of high grade pockets in the footwall, away from that fault, and4. the existence of variograms for the logs with sills parallel to the fault and without sills perpendicular to it.

Jan 1, 1990

Alcoa of Australia's Western Australian bauxite mining operations in the Darling Ranges, south east of Perth, present major challenges in the control of air blast. The close proximity of rural communities and the face profile make the traditional methods of air blast control difficult. An extensive blast noise monitoring programme has been established. The develop- ment of a computerised blast noise prediction model and the establishment of a radiosonde weather balloon facility have reduced blast induced complaints by a factor of ten. The meteorological factors affecting blast noise transmission are discussed and examples are given of adverse weather condit- ions for the south west region of Western Australia.

Jan 1, 1982

By J Andrina, D Richards

The Grasberg is a large copper and gold open pit mine operated by PT Freeport Indonesia and located in the high equatorial mountains of Papua Province, Indonesia. The climate is alpine/sub-alpine with little seasonal variation in temperature and rainfall. The annual precipitation varies from about 3000 to 5000 mm over short distances around the Grasberg, but in general, an average daily precipitation of 10 mm per day applies and leaching of the overburden is continuous throughout the year. Mining commenced in 1988, and almost all of the overburden mined up to 2003 was potentially acid forming. The current acid drainage from this overburden is being collected and treated. From 2004 to the end of the Grasberg pit operation in 2014, approximately 70 per cent of the overburden will be potentially acid forming and 30 per cent limestone. A program of laboratory leach columns, field test pads and an instrumented full-scale dump was developed with the objective of defining scale up factors to quantify the acid and metal leaching rates and to evaluate the stockpile geochemistry and control options. The results of an ongoing seven year program have demonstrated feasible scale up between laboratory columns, field test pads and the trial dump in relation to material geochemistry and ARD evolution trends at Grasberg. The potentially acid forming waste types are highly reactive and maximum acid generation rate occurs within two to three years and that maximum copper release occurs within one to two years of exposure. The results also show that the net acid generation (NAG) test provides a good estimate for the potential acid load from overburden types. The chemistry, temperature and oxygen data from the trial dump suggest that oxidation and acid generation is occurring throughout the dump but at a decreasing mass rate with increasing distance from the toe of the dump. It is apparent that convection and/or advection are important mechanisms for the transport of oxygen into and within the dump. Key results and findings of the investigations carried out are presented and the implications of the findings for long-term ARD management at the Grasberg mine are outlined.

Jan 1, 2003

By V K. Singh, G Sural

The problem of spontaneous heating/fire is very common in coal mines all over the world. The coal industry faces many problems day by day due to the occurrence of spontaneous heating in the open pit coal mines. Presently, about 70 per cent of total coal production in Indian mines is being carried out by open pit mining. Fire in coal, particularly in open pit mines not only causes irreparable loss of natural wealth but also damages the surface structures and pollutes the environment. It is well known that 75 per cent of the fires occur due to the spontaneous combustion of coal. Spontaneous heating is a very common occurrence in coal mines and is a major factor contributing to mine fire. The liability of coal to spontaneous heating causes many serious problems before, during and after mining. In opencast mines, coal immediately oxidises and catches fire due to the intrinsic characteristics of coal, such as low rank, high moisture, high volatile matter, presence of sulfur in the form of pyrites, low crossing point temperature (CPT) and ignition point temperature (IPT) value and less incubation period. In opencast mines, when the coal benches are left idle for a longer time, heat accumulation takes place in favourable conditions and sometimes leads to fire. The purpose of this paper is to present the different successful case studies regarding the safety management of open pit coal mines from occurrences of spontaneous heating/fire.

Jan 1, 2007

Investigation on Sheelite Floatability by Particle Size Fraction

Sep 13, 2010

One of primary causes of poor blast performance is the improper relief of explosive energy. Under or over-confined blasts modify the explosiveÆs path of least resistance, which changes where and when the explosive energy is applied resulting in less than optimum blast performance. During the research for this paper the overbreak characteristics of five full-scale blasts were quantified using high speed cinematography and borehole cameras. The effectiveness of various overbreak control methods was also evaluated to guide design refinement. The results of this research along with general recommendations for reducing excessive damage are included with this paper.

Jan 1, 1999

By Ormsby W. R, Farrar L

The stratigraphy of the central Pine Creek Geosyncline has been simplified into a three-fold subdivision comprising the Batchelor, Frances Creek and Finniss River Groups. The Batchelor Group consists of a sequence of shallow water coarse clastics and crystalline carbonates and is conformably overlain by the marine carbonaceous shale dominated Frances Creek Group. Interbedded within the carbonaceous shale are turbidites, iron formation, tuffs, carbonate and non carbonaceous shale. The Finniss River Group is a flysch sequence of greywacke and mudstone. The stratigraphic and structural evolution and igneous history are all interrelated. Although the Batchelor Group may have formed in a tensional regime, it is likely that regional compression and accompanying thin skinned deformation began during deposition of the Frances Creek Group. Continued compression resulted in D2 folding d6collement deformation, wrench faulting in compressional zones and thrust faulting. Occasional relaxation of compression is marked by a number of periods of basic intrusion and perhaps distal volcanism. The style of deformation within sediments varies away from granitic basement highs and is similar to that observed around salt domes and found in experimental diapiric models. Sedimentary facies changes also indicate local emergence of basement highs during sedimentation. As compression continued, the deposition of thick sequences of the Finniss River and El Sherana Groups brought about regional metamorphism. Relaxation of compression and waning of associated subsidence resulted in a relative increase in the rate of uplift and partial melting of diapiric sialic basement. In places, granitic magma moved upwards and crystallised forming grossly concordant bodies. Other masses moved laterally and formed extensive granitic sills. Later compression periods caused mainly brittle deformation which may have been strongly influenced by underlying basement fabric.

Jan 1, 1994

By Vernon PN

The Eossing Uranium Mine is a high tonnage low grade open pit operation using acid leaching for uranium extraction and ion exchange and solvent extraction for solution purification. Advanced technology, much of it computer based, has led to major economies that have contained operating unit costs over the last four years in the face of double figure inflation. An improved ore reserve block model and mine planning system have achieved a considerable reduction in the stripping ratio. Drilling and blasting costs have decreased some 25%, mainly by the introduction of heavy ANFO explosive. A centralised computer control centre for the metallurgical plant has increased labour productivity resulting in improved process control. The all-staff workforce is united with management in the objectives of creating a safe, healthy, working and living environment and a prosperous company, capable of contributing to the wellbeing of the nation and the shareholders. This situation has been brought into being by an equal opportunity policy coupled with a management system emphasising open two-way communication through all levels in the organisation. The success of this policy is highly apparent in the morale and productivity of the workforce.

Jan 1, 1986

Aspiring to be excellent makes you a good leader as it shows a capability for strategic thought, defining and implementing a vision, making a job easier, more efficient and effective. Every great business leader can generate additional revenue or cost savings for their company. Becoming excellent requires the desire and action to follow it through. There are many established methods of excellence: benchmarking, target setting, supply chain and market analysis, employee suggestions and knowledge sharing forums. In BHP Billiton, practices benchmarking is a key tool in generating improvements for functional areas such as processing, mine operations and mine planning. Practices Benchmarking involves organisational and technical questions that allow the site to self-assess their maturity and generate a prioritised improvement path. Not only does it benchmark and identify gaps, but the approach also facilitates networking, education and team building. For new leaders it is important to remember that you are not alone. Chances are your problem has been solved before. Networks û internal, external, formal and informal can get you started and often save you time and effort. Any leader can achieve success in excellence through a proper process of problem formulation, data and analysis. Again, using key players can make the process more effective. It is important to remember that the people side of the solution is the key to success and that monitoring will ensure the solution will work. In the words of BHP BillitionÆs CEO, Chip Goodyear: Excellence is a mind set. ItÆs something that comes when people get rewarded forthinking outside the box and applying their skill and knowledge. It happens, not in$50 million chunks, but in hundred thousand and million and $2 million chunks.When you get 35 000 people thinking that way, then youÆve really got somethinggoing.

Jan 1, 2005

By Wyborn L. A I, Idnurm M, Hinman M. C

Comparison of the Proterozoic Apparent Polar Wander Path (APWP) for Australia with the corresponding geology of northern Australia suggests that a number of discrete interplate tectonic events, manifested on the APWP as bends or inflections, may have controlled sedimentary basin evolution, ore fluid production and the timing of mineralisation. Similar features in the Phanerozoic APWP for the North American plate appear to correlate with major orogenic events, basin deformation, movement and 'entrapment' of hydrocarbons and minerals. Interplate tectonic events cause intraplate deformation which in turn controls the subsidence/uplift and sedimentation histories of the basins. Interplate events are thus responsible for creating, deforming and destroying sedimentary basins and the associated petroleum and mineral systems. The basins of northern Australia show remarkable similarities in the successions of volcanic and sedimentary deposits. Unconforrnities of regional or sometimes only local extent have been mapped between the major sedimentary sequences and it is predicted that interplate tectonic events corresponding to bends or inflections on the APWP directly reflect the processes that have produced these widespread unconformities. These processes are also likely to have controlled the geometry and character of the fluid migration pathways and hence the mineralising events. Palaeomagnetic studies of Proterozoic rocks in sedimentary basins provide a tool for predicting the timing of regional mineralisation events, particularly for low-temperature mineral systems. The techniques, when coupled with systematic regional basin analysis, using petroleum exploration techniques, may identify a number of new mineral 'plays' in northern Australia. Prominent inflections in the APWP occur at approximately 1700, 1670, 1650, 1600, 1540, and 1480 Ma. Each of these may be related to a regional compressional deformation, important mineralising event, or significant change in style and type of sedimentation. Most appear to be associated with magnetic overprints. Some of the inflections between 1400 and 540 Ma may also mark significant events in the evolution of Meso- and Neoproterozoic basins. Further work is required to correlate inflections in the APWP with alteration events in order to understand their regional significance.

Jan 1, 1994

By M D. Raine, J K. Bartlett, S C. Dominy

The Bendigo Goldfield is located in the state of Victoria, Australia, and is one of a number of fields that make up the Central Victorian Goldfield. Since 1993, Bendigo Mining NL has been carrying out an extensive re-evaluation of the goldfield and is currently well advanced in developing an underground mine. The sediment-hosted auriferous quartz reefs are structurally complex and closely associated with anticlinal axes and reverse faulting. The gold within the quartz reefs is characterised by both its coarse nature (100 up to >5000 ¦m) and its erratic distribution; as a result, the Bendigo Goldfield is classed as an extreme nugget effect system. This characteristic ensures that the Bendigo mineralisation is very challenging to sample and evaluate. In this case, diamond drilling is a good measure of structure and geological continuity, but a poor measure of grade and grade distribution. Drilling, combined with on-reef development, bulk sampling and detailed geological studies are required for resource evaluation. For grade control a balance has to be sought between sample representativness, cost, turn around time and practicality. Extreme nugget effect deposits like Bendigo, require the use of bulk samples in order to be representative. However, the cost and turn around time is significant. As a result, a micro-bulk sampling system has been introduced that attempts to overcome these problems by providing a fast, practical method that can define ore from waste. Bulk sampling and on-vein development are still necessary for resource and reserve estimation.

Jan 1, 2003

The narrow quartz vein deposits at Konongo and Ghana Main Reef gold mines in Ghana were emplaced during the plastic flow cross folding of pre-existing sub-isoclinally folded volcanic and perivolcanic deposits of Proterozoic age. The older fold structures tightened differentially according to their position in relation to the axes of the cross fold pattern giving complex outlines to the reefs in both plan and cross section.Some 4500 measurements of bedding plane linears were used in the resolution of the Boabedroo footwall structure at Konongo. The methodology developed at the Boabedroo mine was then successfully applied to other complex bodies at the Konongo and Ghana Main Reef mines.All mine development, especially stope preparation, of the folded quartz reefs at Konongo and Ghana Main Reef was controlled by the geologist to ensure that the veins were removed with as few geologically enduced hiccoughs as possible.

Jan 1, 1993

By Katom M

Each of the two 32 feet diameter Semi Autogeneous Grinding (SAG) mills at Ok Tedi's copper and gold concentrator was treating at best 1500 tph at about 65 per cent mill availability in 1988. The process was effectively unmeasured and used manu

Jan 1, 1997

The effects of process variables such as solution chemistry, flocculent type and dosage, intensity and duration of mixing, and solids type and concentration, on the performance of flocculation/clarification/thickening processes are described. System response is evaluated in terms of the specific effects on floc settling, supernatant clarity and sediment compressibility. The implications of these results with respect to industrial practice are discussed and general guidelines for direct application to plant design and operation are suggested.

Jan 1, 1993

Close spatial relationships between the deposits of the Etheridge Goldfield (23,000 kg of bullion) and various regional geological and geophysical features suggest that genesis of the ore deposits was a multi-stage process that started with magmatic and metamorphic stages in the mid-Proterozoic, climaxed with structural and hydrothermal stages in the late Palaeozoic and terminated with an oxidation enrichment stage in the Cainozoic. Acceptance of this hypothesis permits classification of the Georgetown region into areas likely to contain deposits of the Etheridge type and those unlikely to do so. Consequently there is little scop- for the discovery of extensions of this field. However, the stratigraphic interval between the source rocks of the Etheridge field and stratigraphically higher host rocks of the Croydon field may contain disseminated replacement gold deposits of the Carlin type. The potential host (pyritic carbonaceous, and locally dolomitic siltstone of the Candlow Formation) is locally faulted and cut by granitoids and the extension of a mineralised, long-standing zone of structural weakness.

Jan 1, 1980

By Gray E, Banks J

In mine site revegetation, exotic grasses are more commonly used than native grasses. This is due to unavailability of native grass seed on a commerical scale and lack of information on agronomical aspects of native grasses. This paper lists a number of native grass species that have the potential to grow well on mine sites, and provides some information on their seed collection, processing and germination. Further, it demonstrates via results of a field trial conducted at Ranger Mine spoil the relative performance of ten native grasses and Rhodes grass. It is concluded that (i) some native grasses have similar ability to grow on mine spoils compared to Rhodes grass and (ii) the use of native grasses have added advantages in ecosystem restoration.

Jan 1, 1994

By Peng S. S

Measurement of pressure distribution under the base plate of the Hemscheidt 2-leg 800-ton shield was performed underground for two shifts using 12 pressure cells installed in two rows, one each under each split base plate. Pressure distribution was uneven depending on contact condition. In general the highest base pressure occurred at 1/3 of the base plate contact length from the rear edge. The resultant was near vertical, and the pressure under the tail side split base plate was always higher than the head side. For comparison, pressure distribution on the canopy and under the base plate was also measured under controlled conditions at the USBM's Mine Simulator Testing Facilities in Pittsburgh, PA. A total of 45 tests were conducted under several simulated contact conditions. The results showed that the actual contact area is highly dependent on the compliance of the immediate roof and floor due to the sloped canopy tip and a base lifting device under the base tip. The loading distribution tends to change in magnitude and profile as the leg pressure increases. The base lifting device exaggerates the high toe loading on the base plate characteristics of this type of shield support.

Jan 1, 1992