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By Johnson RD

The variation in coal properties and the coal seam reduced level can be analysed using partial trend-surface analysis techniques. For the area studied seam reduced level and seam thickness data from the Bulli Coal yield trend-surfaces with a high coefficient of determination, since they have relatively small systematic local and random components in their overall variation. Sulphur content appears to have no significant re.gi_onal trend, and phosphorus content has a very weak regional trend. Other analytical variables have regional trends which are of intermediate strength. The strike-directions of.the statistically significant first degree! trend-surface are similar, sug-gesting.: that the variation of the several coal properties was controlled by a set of- related causes. The relations apparent from the dip and strike of the first degree trend-surfaces are similar to- those which are apparent from the trend- surface residuals and'from the results' of canonical trend-surface analysis.'.. It is probable that differential subsidence controlled the areal

Jan 1, 1975

Intermontane valleys form unusual features of compressive mountain belts both in the sharp topographic break they represent and in the strike-slip displacements often associated with the valleys. Such strike-slip motion seems hard to reconcile in the actively deforming Andes where reconstructions have indicated nearly perpendicular Cenozoic plate convergence. Detailed study of a part of the Argentine Andes between latitude 31-33¦S suggests that, although strike-slip displacements may have largely created a prominent intermontane valley system, no Holocene strike-slip displacements are observed amid the relatively active compressional deformation along the mountain belt flanks. New plate reconstructions, treating the Nazca plate as two microplates separated by fractures along the Nazca Ridge, predict large components of strike-slip motion between the South American and Nazca Plates for the period from 10 to 5 Ma. These reconstructed plate motions are consistent with strains derived from recent kinematic analyses of minor faults along the southeast margin of the Puna plateau and the general timing of tectonic phases in the Andes.

Jan 1, 1987

By M F. Lee

In order to make good decisions, as to whether large diameter raise bored shafts can be constructed in blocky rock at a particular location, mine planners, management, geotechnical engineers and contractors must understand and consider a range of geotechnical issues. Firstly, mine management must ensure that adequate time and resources are available to find appropriate shaft sites. Deep weathering, adverse structures, groundwater, etc might mean that the most desirable location, with respect to other mine development, might not be suitable. Special site investigation drilling, etc may be necessary. Even then, alternative construction options might be necessary, other than just reaming through to the surface. A site investigation borehole should then be drilled to investigate specific and general ground conditions along the raise alignment. Often, only small sections of weak blocky rock dictate raise stability. While the empirical McCracken and Stacey method is typically used in Australia to assess raise stability and assess geotechnical risk, until recently it had no published performance data.An Australian database of raise performance now exists and is presented below, courtesy of an industry survey by the Eastern Australian Ground Control Group. Raise diameter and ground conditions (in terms of a lower bound Qr value) is presented for 50 cases versus raise performance.

Jan 1, 2008

By I Taylor, M Nugus, C Gordon

Resource estimation and selective mining of structurally complex, high nugget orebodies presents a major challenge to the Mine Geologist. At the Golden Pig BIF-hosted gold deposit in Western Australia, an estimation method has been developed that replaces an assay-based resource estimate with one based on mineralisation intensity. Subjective coding of the mineralisation intensity has a more robust connection to local grade than drillhole assays. Indicator variograms of the five mineralisation codes are well structured with anisotropy directions similar to observed structural controls. The proportion of each mineralisation code is estimated and a weighted average of the average grade of each code calculated for a block. Initial validation has shown that the model is a good predictor of the mineralisation intensity, and the application of appropriate local average grade for each mineralisation code gives a reliable block grade estimate.

Jan 1, 2003

This paper will discuss the challenges and opportunities in the years 1998 to 2002 faced by the operation and personnel at Thalanga, and its continued survival through short life projects (three feasibilities in four years). It will describe the processing of the different ores, issues faced and operating and technical innovations that occurred during that period. This will include: commissioning on very high grade Cu ores, treatment of high Sulfur feed ores (~46 per cent S) and the effects of the installation of a Detritor Mill on the process.

Jan 1, 2003

By Hodges D. A

The manufacture of steel from raw materials which have to be mined, transported and processed must affect the environment. Steelmaking, like almost every other stage of manufacture involves the unwanted production of dust and fume; thus a major part of the steel industry's effort to minimize changes to the environment is the collection, treatment and recycling of dust and fume to avoid pollution of the atmosphere and waterways. The paper describes how this achieved in the various steelmaking processes and shows the diversity of problems-and their solutions in this context. Particular emphasis is, given to basic oxygen steelmaking.

Jan 1, 1976

By Galecki G

The investigations conducted in the High Pressure Lab at the University of Missouri-Rolla demonstrated the ability of high pressure waterjets to excavate coal and minerals, disintegrate materials and as well as to comminute coal and minerals. Additional progress in comminution can be achieved if the compressive crushing principle commonly used at present is changed to one where particles are fragmented by the tensile growth of preexisting internal flaws or cracks, under internal waterjet pressure. This idea was studied in a number of tests. It covers tests with different jets imposed on coal and rock samples during compressive load as well as without any loading.

Jan 1, 1993

By J S. Petersen

The occurrence of coarse gold particles leading to grade complexity and sampling challenges is a common feature of many gold deposits. Poorly designed sampling protocols applied to these deposit types can lead to an excessively high fundamental sampling error. Together with other errors, the fundamental sampling error contributes to the nugget effect. Proper sample collection, preparation and assay protocols are required to minimise this error, and hence reduce the total nugget effect. Reduction of the nugget effect is a key requirement for subsequent geostatistical resource estimates to be effective. A case study from the Nalunaq gold mine in Greenland is presented, which is characterised by notable quantities of coarse gold (>30 per cent +100 ¦m gold) hosted in quartz veins. Diamond drilling provides a good measure of gross geological continuity at practical grid spacings, but is not considered to represent the mineralisation effectively. On-reef development with face and bulk sampling, together with detailed geological studies were undertaken during the resource delineation phase. This contribution describes the nature of the Nalunaq deposit, its gold particle size characteristics, how sampling and assay protocols were developed (including QA/QC issues), application of GyÆs sampling theory and its calibration, and how the data was subsequently applied to grade estimation.

Jan 1, 2005

By Hikosaka A, Chiba A

In a fundamental study of the physical chemistry of steelmaking slag, equilibra bet- ween hydrogen-water vapour gas mixtures and liquid slags contained in solid iron crucibles have been measured for four binary slags, FetO-CaO, FetO-Si02, FetO-TiO2 and FetO-Al203 at 14000C. From the data, the activity of iron oxide and the ratio of ferrous and ferric ions (A = Fe3+/Fe2+) were calculated for the slag composition. The best ionic model is found to be that based on regular solution of cations. The oxygen distribution between slag and metal is quantitatively expressed by this model over a wide range of slag composition.

Jan 1, 1980

The implementation of a process information management system (PIMS) is to provide a single online, real-time information system. This system provides a unique and completely open view for everyone, based on the key business drivers. It is structured around the three key concepts: process, maintenance and stocks. It combines numerous applications and provides accessibility to common tools and reports, through a web-based user interface, for every one from the floor operator to the General Manager. This æunique and commonÆ view displays raw, online process information that provides a quick health check of the operation at a glance, highlighting areas that require further investigation. The system is based on a hierarchical system of views, from the overview of the whole plant flow sheet to the more detailed operational shop view. It provides a synthetic view between continuous and batch operations, enabling the tracking of each batch produced. The batch view displays the critical batch components, and a comparison with each component of an ideal batch. This enables detailed analysis of each batch to identify areas of improvement. The information system will consist of an online reconciliation of stocks and flow data. This enables focus on the recovery of each process unit on a regular basis. This paper discusses the design strategy for the Process Information Management System, to ensure a unique and open view on the key business drivers is achieved and implemented successfully.

Jan 1, 2005

The, Ore-bodies.-The ore-bodies of the North mine, North Broken Hill Ltd.; consist of two lenses, connected by a narrow neck of mineralized country. They pitch at an angle of 40° in an easterly direction and dip north at 60° to the horizontal. The southern ore-body, on a horizontal plane, has a total maximum length of 800 feet and in one place attains a width of 230 feet, whilst the northern orebody has a maximum'length of 600 feet and a maximum width of 80 feet.

Jan 1, 1940

By Nye P. B, Fisher N. H

At the second Empire Mining and Metallurgical Congress held in 1927, the Empire Council of Mining and Metallurgical Institutions was formed and it was proposed that the Council take steps to prepare a "Review of the Mineral Resources and Industries of the Empire." At the third congress in 1930, it was resolved that the proposal to institute the review should be submitted to the Imperial Conference held in 1930. This was done, and the Minerals Committee, of the Imperial Economic Committee compiled, an interimreport which was based on statistics of imports and exports, and did not consider resources and consumption.In 1942 the Institution of Mining and Metallurgy, London, wrote to the Empire Council and stated that it was desirable that the Council should be in a position to take part in decisions affecting the future of the mining and metallurgical industries. The Council communicated with the constituent Institutions regarding the nominations of two members then in England. Subsequently the Mining, Geological and Metallurgical ,Institute of India prepared a review of the mineral resources and industries of India and their post-war development, and the Empire Council forwarded a copy to the Australasian Institute of Mining and Metallurgy and asked if that Institute would submit a review on simjIar lines for Australia. The Australasian Institute arranged that the Australian review should be prepared by...

Jan 1, 1946

By M Titley, E Maidens

Many gold deposits were mineralised by fluids and processes that also altered the host rocks. This alteration may often be a useful visual aid that distinguishes barren, low-grade from high-grade regions in a rock mass. Alteration intensity is commonly used in gold deposits as a visual tool, along with face sampling or grade control support, to define oreblocks and guide excavation in underground and open pit mining. However, alteration is not often used at the resource estimation stage. Mineralised lodes are usually defined by geologists using a ægeo-grade envelopeÆ, where a number of constraints are considered, including an (arbitrary) cut-off grade; the ænaturalÆ grade break between high- and low-grades; and geological features including structural, lithological or alteration continuity. The geo-grade envelope is usually thought to satisfy the requirements of stationarity for grade estimation, and is considered a single domain. This paper examines a modelling technique combining gold grade and alteration, applied to the Wallaby deposit in Western Australia, to imbue a greater level of detail to the grade estimation in a region tested by relatively sparse drilling. This was achieved by utilising the correlation of gold grade and alteration, along with the spatial characteristics of the alteration, when estimating grades within a number of lodes. The alteration-driven estimation was utilised in conjunction with an unfolding approach, and the use of probability estimates, to overcome geometric data constraints. This technique allows greater control and most likely provides a more reliable estimate of the mineable resources than a global grade cut-off when visual control is to be a major vector in grade control.

Jan 1, 2003

By M Hudyma

Open stope mining is the most common mining method employed in underground, hard rock mines in Canada. It is characterised by relatively small, single lift stopes (20 000 to 100 000 tonnes), and fast stope turnaround times. Host wall rock mass conditions, which are typically poor to fair, are the controlling parameter in stope dimensioning. Rock mass stability is maintained by designing all stope surfaces at a stable dimension, and through extensive use of cablebolting for stope backs and frequently stope hanging walls. Dilution control is a high priority. The typically small, high-grade, deep and irregularly shaped orebodies are incrementally developed, usually in a bottom to top direction. In many cases, high stress is encountered due to the depth of the orebodies. Overstressing of pillars and hanging pillars are avoided through the use of pillarless or early pillar recovery mine sequencing strategies. Stopes are invariably filled, and in higher grade and wider orebodies, cemented fill is commonly used. This paper generalises many of the similarities found in Canadian open stope mines.

Jan 1, 2000

The occurrence of metallic minerals in Australia to the time of the proclamation of South Australia as a Colony in 1836 was unknown. It is, therefore, perhaps, surprising that British settlers arriving in the Coromandel included among their number a German scientist Johannes Menge who had been appointed by the South Australian Company to the post of Mine and Quarry Agent and Geologist on 1 July 1836. His instructions were to `explore the natural productions of the Colony above and below ground and to superintend the working of quarries of stone and slate, the boring for water, metal, lead, coal and other mines at a salary of ú150 per annum for one year and for as much longer as the Company require your services not however exceeding five years'. In the event, he was to have little influence on those matter.

Jan 1, 1993

By Kneisley RO

This paper presents a brief overview of current bump mechanics theories and pillar design methodologies, and relates these concepts to experiences at two mines located in a north- central Utah coalfield where different pillar designs were used to control mountain bumps. Experiences gained at the first mine demonstrated the successful implementation of a two-entry, 9.8 m (32 ft)-wide, yield-pillar design. A U.S. Bureau of Mines field study quantified the timing of chain pillar yielding and resulting load transfer from the gateroad. In-mine pillar response, although apparently sensitive to site-specific conditions, compared favorably to estimates derived using two yield- pillar design methods. A second study conducted at another mine located in the same district, but subjected to different geologic conditions, documents the unsuccessful attempts to employ progressively narrower three-entry pillar designs based on successes achieved at the first mine site. This second mine never achieved a true yield-pillar design. Use of pillar widths ranging between 9.1 m (30 ft) and 27.4 m (90 ft) always resulted in violent bumps in the tailgate pillars. The pillars were either too large to yield, or too small to support peak operational loads. Hypothetical gateroad systems were evaluated using both analytical and empirical approaches for configurations comprised of two rows of conventional pillars, and systems incorporating both yield and abutment pillars. Analysis concluded that yield pillars less than 6.1 m (20 ft) wide and abutment pillars ranging between 30.5 m (100 ft) and 39.6 m (130 ft) square would be required to achieve a stable gateroad design. However, results of a field study conducted on a two-entry, 36.6 m (120 ft)- wide abutment pillar concluded that abutment pressures from the first panel overrode the pillar, and that a still larger pillar may be required to preclude bumps in the tailgate during second panel mining. Without the benefit of a demonstrated in-mine success, it is not clear which design would ensure elimination of gateroad bumps.

Jan 1, 1992

In any open pit mine some slope instability may be expected. This can range from small scale sliding on individual benches to large scale overall slope failure. This paper presents two case histories which illustrate how mining has successfully continued despite major pit instability. The common threads in each of these are listed below. 1. The recognition of the type and nature of movement (either regressive or progressive). 2. The successful application of simple monitoring techniques to minimise the potential impact on the mining operation, and 3. The management of the waste and ore excavation to avoid potentially damaging and costly situations.

Jan 1, 1986

There are many factors influencing the way in which a mining company disposes of tailings. Some of the more important factors include physical and chemical properties of tailings, cost, availability of dam wall construction materials, type of mining operation, topography and environmental constraints. As a result, the mining industry has seen a diverse and innovative range of disposal methods developed to satisfy the many conditions imposed at tailings disposal sites. This paper discusses a range of tailings disposal methods currently practiced in the mining industries in North America. These methods include various inpit disposal techniques, upstream, downstream and centreline dam construction and zoned earthfill or rockfill embankment construction. The thickened tailings disposal method and the disposal of fine clays are discussed. The importance of improving the depositional properties of tailings to enhance storage capacity, water reclaim, dam wall stability and final reclamation is stressed. It is important that mining companies are made aware of the full range of disposal methods and dam construction techniques available today. Such an awareness will help improve the planning, design and construction of safer and more efficient tailings disposal facilities in the future.

Jan 1, 1989

By C Gypton

This paper gives some insights into what to look for when reviewing feasibility studies. The review by a third party is an important element of the risk management process and may be the last remaining opportunity to uncover errors, or identify and reduce project risks on paper before they are converted to financial disappointments, steel and concrete monuments to process failures or cost overruns. The mining industry has had a spotty record in the area of estimating initial capital costs and operational performance, even though the standard of feasibility studies is generally acknowledged to have improved in the last decades. Third party reviews rarely have the luxury of enough time and unlimited funds, so where should the reviewers focus their efforts to be most effective? Assuming that the project already apparently meets investment criteria, the authors suggest where and how to look among fundamental project parameters for signs that serious flaws exist that have the potential to become project killers. We also give advice on how to review cost estimates without becoming lost in the details. The paper is supported with numerous actual examples.

Jan 1, 2003

By Griffiths J. B

From its mining lease at the northern end of Cohens Reef at Walhalla in the North Gippsland Mountains, the Long Tunnel Extended Gold Mining Company produced 13,695 kg of gold, which at 1980 prices represents a value significantly in excess of $200 million. In the period 1885 to 1908 the mine was one of Australia's principal reef gold producers, being top Victorian producer in six of these twenty-four years. Prior and subsequent occupants of the lease produced an additional 160 kg of gold. The Extended and the other mines on Cohens Reef whilst contributing importantly to the financial resource of Victoria, were the sole important support for the substantial town of Walhalla that had grown up around them. When the mines closed, Walhalla gradually reduced from a bustling developed town to the present attractive mountain village so favoured by tuurriSts. To allow the visitor to obtain a better ;ri.icrstanding of Walhalla's mining past, important parts of the Long Tunnel Extended Gold Mine workings and site are being

Jan 1, 1981