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By Leigh G, Gottleb G, Wilkie G

The estimation of particle liberation is important in the study of mineral concentration. With simple systems, where the densities of the components are low, the liberation can be studied directly by density fractionation. For most practical systems, and particularly for the dense, complex sulphides, the only method known is by measurement in polished section. There are two major difficulties with such measurements. Firstly, the measurements themselves are difficult and considerable care is needed before reproducible results can be achieved. Secondly, a well known stereological problem arises which gives the estimates an inherent bias. The paper discusses both aspects of the problem. The practical features of measurement are treated in detail and a method described which has been developed and proven to give reproducible estimates of the liberation in the section. This discussion relates to automated measurements by QEM*SEM and presents a way of estimating the confidence limits within which measurements lie. Comparisons are shown between measurements made by the traditional manual optical technique and automated equipment. Stereological reconstruction is also discussed briefly. Several methods have been presented in the literature but all are complex and none is yet widely accepted. Area measurements are less biased than linear estimates so a practical approach is to use area measurements in uncorrected form. The topic is still being actively researched so it is expected that one method will soon emerge as the standard technique.

Jan 1, 1993

By O Ostrovski

Iron ore reduction and iron cementation by CH4-H2-Ar gas was investigated in a laboratory isothermal fixed bed reactor. Iron ore was first reduced to metallic iron by hydrogen, then carburised to cementite by methane. Increasing temperature and hydrogen content accelerated the reduction process. Methane had almost no effect on the reduction process. Meanwhile, higher temperatures increased the rate of cementation and also the rate of free carbon deposition. The optimal temperature for cementite formation was found to be 750¦C. At this temperature, reduction of iron ore to cementite by gas containing 55 vol per cent hydrogen, 35 vol per cent methane and 10 vol per cent argon was completed in about 15 minutes. Addition of sulphur into the reducing/carburising gas strongly retarded the process of cementite formation and free carbon deposition. Cementite is an unstable phase which decomposes to iron and carbon. The rate of cementite decomposition increased with temperature up to 600¦C and above 750¦C . In the temperature range from 600¦C to 750¦C the rate of cementite decomposition decreased with temperature. Cementite was the most stable at 750¦C and least stable at 600¦C. The two-interface grain model was used to describe the process of iron ore reduction and the volume reaction model was employed to model the iron cementation process. The simulated results for both reduction and cementation are consistent with the experimental data.

Jan 1, 2000

By J Kleynhans, D Vermeulen, V Cogho

A number of rehabilitated open cast coalmines in SA are already decanting. The paper focuses on the situation at one of these mines where the following information exist: monthly decant rates and rainfall; sulfate concentrations of the decanting water; water level measurements inside the mine prior to decanting; ABA analyses; information about the rehabilitation (drainage slope, vegetation, soil used). A 2D-model was constructed for the mine and calibrated against six years of flow data. About 85 per cent of the decant outflow rate comes from direct recharge on top of the rehabilitated mine while the other 15 per cent is derived from lateral groundwater inflows. The estimated recharge value was 17 per cent of the rainfall. Measured sulfate values showed that the sulfate generation rate for the mine was in the order of 7 kg/ha/d. Conclusions from the study are:most of the water decanting from rehabilitated open cast coal mines is derived from recharge via rainfall; given a specific sulfate generation rate, then: the lower the recharge the less the decant rate but the higher the sulfate concentration of the decanting water and vice versa; future prediction of the decant rate must be stochastic according to expected percentile monthly rainfall values; and as a first assessment of the predicted sulfate concentration of decant water from rehabilitated open case mines, the 7 kg/ha/d sulfate generation rate can be used.

Jan 1, 2003

With the recent wider introduction of friction hoists of the Koepe type. for winding from depths of more than 3000 feet it has been found that failure by fatigue is the most common form of rope deterioration. Large numbers of wire breaks occur near the centre of the rope cross-section and it is difficult to detect these with certainty using the preferred d.c. magnetic test. For best results with conventional search coils their dimen- sions should be related to the typical wire break field pattern surrounding the longitudionally magnetised rope. The field of a broken wire was experimentally determined, using a Polish type MD6 Defectograph wire rope testing magnet and a short prepared length of rope with a movable simulated broken wire. The external field distortion perpendicular to the rope was measured by means of a gaussmeter and Hall probe. The advantages of this method are that terrestial magnetism and inherent rope "noise" have no effect on the results.

Jan 1, 1971

This paper summarises some observations regarding the way SAG and AG mills work based on the last ten years of pilot plant operation, grinding circuit design and operational reviews for various projects in Australia and overseas. The main purpose is to promote discussion on key factors influencing breakage in a SAG mill. The focus of the paper is on two questions: How do mill lifters and liners really work and have an effect on grinding? How does the mill charge composition impact on grinding performance? The focus of the paper is on observations of mill behaviour in both pilot plant trials and plant operation, particularly on Cadia ore. DEM, by others, and JKSimMet modelling of SAG mill performance have greatly assisted in forming the ideas expressed in the paper and both are valuable tools in developing our understanding of the comminution process. Put in the æextremeÆ form the major observations and conclusions expressed in this paper are that: the main purpose of mill lifters is to reduce mill liner wear and not to promote rock breakage; the often promoted theory that balls impacting the ætoe of the chargeÆ is a dominant form of breakage is incorrect; and fines production in a SAG mill is primarily a function of the rock load mass, with a secondary dependence on ball load for any given circuit configuration.

Jan 1, 2007

By N Ozawa, R Kaneko, M Arimit

The Mitsubishi Higashitani limestone mine is a ten million tonne per annum operation located near the city of Kitakyushu on JapanÆs western island of Kyushu. Higashitani is one of the largest limestone mines in Japan and accounts for about five per cent of national production. Blasting practices at the Higashitani mine involve the use of bagged ANFO, dynamite primers and non-electric detonators. Regulations in Japan prohibit the use of site mixed bulk explosives. Blast size is usually around 17 000 tonnes with 20 holes in a single row, two or three blasts are fired per day at a powder factor of between 0.25 and 0.32 kg/m3. As part of a program looking at oversize reduction Mitsubishi, Asahi and Orica agreed to conduct a joint project at the Higashitani mine to investigate the relationship between the powder factor and fragmentation. The first stage of the project was to benchmark the current blasting performance. Five blasts were monitored in each of the 210 (hard rock) and 220 (soft rock) areas of the mine. OricaÆs Powersieve« software was used to measure fragmentation and total rock breaker hours were also recorded for each blast. OricaÆs computer blasting simulation model Sabrex« was used to prepare revised blast designs with a higher powder factor and predict their performance. The performance of these blasts was monitored using the same methods.

Jan 1, 2004

By Purvis A. H, Greenwood-Smith R, Sowerby B. D

A nuclear technique for the determination of copper and nickel in bulk samples and drill core has been developed at Lucas Heights andfield-tested at Mount Isa. The technique, which is highly specific to the element being measured, utilises the gamma-ray resonance scallering process.A bulk mineral analyser was installed in mid-1976 for the routine assay of copper in bulk samples and drill cores, and remained in operation until late 1981. The operation of the analyser over this five-year period is reviewed with particular emphasis on reliability, accuracy and principal usage.The main application of this analyser was in stope planning and design whereby several thousand drill-core and Wall-chip samples were analysed. It was also used as an aid to underground grade control of stopes where ore dilution by supporting barren backfill was a problem.

Jan 1, 1984

This paper reviews the developments in understanding of the entrainment mechanism and its modelling in industrial flotation processes over the last 30 years. Both valuable and gangue minerals in the pulp zone of an industrial flotation machine can be transported through the froth zone to the concentrate launder in the water which must also be transferred from the pulp zone to maintain a stable froth zone in conventional flotation. A size dependent portion of each entrained mineral continues in normal circumstances to the concentrate launder. The size dependency arises because the larger particles are able to drain more successfully from the froth region. Gangue minerals are recovered by a number of mechanisms, entrainment being an important one in many cases. The entrainment mechanism is discussed on the basis of the pattern observed in recovery û size data for minerals. Its industrial implications are discussed and means of minimisation of the importance of the mechanism are also discussed. Various means proposed for mathematical modelling of the entrainment mechanism are also described. The effect of process variables on key parameters in these models is reviewed. Properties of both the pulp and froth zones are discussed where needed and means of taking additional measurements with devices developed over the last ten years are discussed as part of the collection of more detailed data on the flotation process in general and the entrainment mechanism in particular.

Jan 1, 2005

WHEN reading reports on reefs and lodes, one often comes across the statements "short shoot," "narrow shoot," "wide shoot," & c.From a number of reports in the writer's possession, some by members of the Geological survey, it is plain that the words "short," "narrow," "wide," "long;" &c., are used somewhat carelessly.In one official report on a certain field, for instance, the reefs are described as having "short, rich shoots"; another report on the same field states that "the reefs were characterized by narrow shoots, rich at the surface." Again, Charters Towers is described as having "wide shoots"; another writer says they are "long shoots. "The writer has read again of "short shoots which went down like pipes," and of "narrow shoots of limited extent." No doubt one can make out what is really meant, but the language is mixed. It is apparent that "narrow" is meaning the same as "short," and that the shoot has not much length in a horizontal direction. Nothing is said about the thickness or width of 'said shoot, or its depth. The "wide" shoot is evidently a "long" one; its thickness 01' width and depth is not specified. When we consider these terms, it is seen that only a few words are needed, and that these few should (as they do) have a definite meaning. In the course of his mining experience, the writer has seen shoots of almost all sizes, and some have been very long (in horizontal measurement), and have been followed down for great depths, these shoots being the best type-Charters Towers, Walhalla, &c., are examples.

Jan 1, 1909

Technical control in an industrY invariably leads to a basic contribution from the science of chemistry. It is interesting to note. that the change from the "Assay Office" to the "Chemical Laboratory" has already taken place on the majority of progressive mining fields.Although the serlvices of an efficient chemical staff are freely availed of by operating departments, it is not generally realized that practical chemistry is definitely expensive. A great deal of misplaced energy and expense can be involved in an enthusiastic research campaign where a full appreciation of laboratory economics and a balanced sense of analytical values are lacking.In order to supply data to the various departments concerning individual costs, it was decided at the North mine to issue a supplementary sheet concerning laboratory activities.The costs are compiled under the Unit System, which is based on a relative comparison between the total cost of the various determinations. carried out and the number of such determinatiQns converted to an equivalent aggregate of units.The introduction of the system necessitates the initial compiling of a table of relative units for the various estimations carried out on the works. Each laboratory will find it necessary to draw up such a table governed by local conditions, and, as will be anticipated, a relative comparison of the cost for any particular estimation will show a variation on a lead field, a copper field, or a steelworks, etc.This is due, of course, to the predominating type of routine work, cost of landing reagents, frequency of assays, etc. The satisfactory preparation of the Unit Table requires a good knowledge of laboratory procedure.

Jan 1, 1940

The investigation of Noapara glass sand deposit in Sylhet district of Bangladesh is performed to beneficiate the sand for the manufacture of colourless glass. For the ease and efficient removal of the colour bearing impurities, the physical and mineralogical investigations of the sand deposits is carried out first. The sand is then treated with the standard beneficiation procedures to reduce the impurity level to an acceptable level. It is found that the Noapara glass sands are of medium grained and moderately sorted. They contain 0.15 - 0.30 per cent Fe2O3 and 0.001 -0.008 per cent Cr2O3 as major colour bearing impurities. The heavy mineral fractions containing most of the impurities can be grouped into five types of associations:stable or ubiquitous minerals (tourmaline, zircon, rutile); metamorphic species (staurolite, kyanite); amphibole minerals (hornblende, tremolite); the micas (muscovite, biotite); and discrete minerals (magnetite, ilmenite, etc). It is also seen that, the use of mechanical separation process in combination with water washing, attrition, and magnetic separation can remove a maximum of only 70 per cent of total Fe2O3 present in the deposits. This is insufficient to produce the specified grade of sand to manufacture colourless glass. Among the various chemical treatment processes used, sodium dithionite method is found to be the most effective, although the discrete minerals are not removed. Using the specific reagent group during froth flotation, the iron and chromium contents are reduced to 0.03 and 0.001 per cent respectively which are very near to the specified colourless glass composition.

Jan 1, 2000

The purpose of this paper is to outline the equipment used for diamond drilling at Mount Isa, together with alterations and recent improvements therein. As the majority of the drilling is carried out with machines running at relatively high speeds using XRN blast hole bits, the paper is mainly devoted to this branch of drilling.Because diamond bit costs constitute the major expense, a considerable amount of research into bit design has been carried out, and in several instances, costs per foot have shown an appreciable decrease in spite of rising manufacturing costs and higher diamond prices. Equipment performance has at times been erratic due to delays in delivery and occasionally because of faulty parts, but in general the position has improved by keeping in close contact with the manufacturers.BLASTHOLE DRILLING MACHINESThe standard blasthole diamond drill is the 'E-500' two cylinder air powered model manufactured by Mineral Drillers Limited. Several of the older pattern JV41 are still in use, but are being retired as they wear out.. Machines are repaired in the underground diamond drill shop.The normal feed gears used when drilling in lead shales are 350 top gear and 450 low gear-actually 357 and 438 revolutions per inch of advance respectively. The 300 gear was commonly used several years ago, but it was found that bit footages could be increased without any appreciable drop in penetration rate by reducing to the 350 gear. Gears used for copper drilling are 650 and 750. Footage per shift...

Jan 1, 1953

The Permian coal in the Muja Coal Measures of Collie Basin of Western Australia has a subdued lustre because of the fine laminations of lithotypes, and the dominance of dull and dull banded lithotypes with minor bright, bright banded and fusinous types. The maceral composition of the coal is variable, however the macerals of vitrinite and inertinite groups dominate and the exinite and mineral matter contents are low. The lithotypes have low concentrations of trace elements and the boron concentration is between 10 - 100 ppm recorded only from the dull lithotypes. On the basis of organic petrology, the inter-seam sediments, flora and the very low concentration of boron, the depositional environment postulated for the coal is braided, fluvial and fluvio-lacustrine with marked fluctuations in the water table. The low water table in the environment accounts for fusain and inertodetrinite in the coal.

Jan 1, 1996

Prospecting in arid terrain can produce substantial environmental impacts, comparable to or greater in magnitude than the impacts associated with actual mining or petroleum production. Impacts are likely to be particularly severe where prospecting involves intensive geophysical exploration, especially in areas which have escaped degradation by other land uses such as pastoralism. With appropriate environmental planning and management, however, the environmental impacts of prospecting in arid terrain can be greatly reduced and mitigated, at low cost. In many countries, prospecting licences, exploration leases and associated tenements now carry a range of conditions relating to environmental protection. The assessment, avoidance and mitigation of environmental impacts is therefore an important component of and-zone exploration. My aim here is to give an overview of some of the main aspects of an environmental planning and management (EPM) programme for prospecting in arid terrain (PAT). Detailed operational prescriptions for environmental protection procedures are necessarily specific to particular areas and types of prospecting: see. e.g., Buckley (1982a, 1984, 1985a, 1986a), Klepacki et al. (1985) and Stone (1986). The intention here is to provide a checklist rather than a recipe book: as an aid in incorporating environmental aspects into the overall planning and management of an exploration programme, and in liaison with company environmental staff, consultants and regulatory bodies. I also hope to show that whilst some of the techniques used in particular environmental disciplines certainly require specialist expertise, the overall design of an EPM programme is not in the least esoteric, but simply an exercise in straightforward common sense. Perhaps this paper could be subtitled: "Demystifying environmental Planning".

Jan 1, 1988

Evidence for Middle-Late Triassic large-scale, silicic volcanism characteristic of extensional continental terranes is widespread in the Tasman Orogenic Zone in Eastern Australia. Detailed study of an area of south-east Queensland has defined the eroded remnants of a large collapse caldera and an associated area of rhyolite dome building and regional downsag which may be a second caldera (Stephens, 1986). The silicic volcanics and minor basaltic to andesitic products have been assigned to the Aranbanga Volcanic Group (Cranfield, in prep.) and the associated granite complex has been named the Mungore Complex (Ellis, 1968). Published isotopic age dates on the Mungore Complex are 212-219 m.y. (K-Ar Biotite; Ellis, 1968) and 226 m.y. (pooled Rb-Sr on several similar plutons in the region; Webb and McDougall, 1967). Basalts within the area have been dated at 219 m.y. (GSQ Annual Rpt., 1986). The collapse caldera (Mungore Caldera) lies on the intersection of 4 major structural features: 1) the Mt. Perry Lineament, a meridional fault zone extending for over 600 kilometres in a NNW-SSE direction and which has faulted the eastern part of the caldera 5 kilometres sinistrally. The lineament has been active at least from mid-Permian to Late Triassic and has localised activity into the Tertiary. Granite plutons of the same age as'the Mungore Complex- are topographically prominent and largely concentrated east of the Mt. Perry Lineament and its extensions (Nash, 1986); 2) the extension of the Darling River Lineament, a continental-scale, ENE trending feature which correlates with regional structural discontinuities but which lacks expression as faults within the Tasman Orogenic Zone;

Jan 1, 1987

By Goto T, Sato K, Mori N

A field investigation by making use of the seismic method has been carried out in order to comprehend the mechanism of rockburst and gas outburst and their predictive measures. The seismometers were so arranged both on the surface and underground as to enclose a mining panel. Seismic signals detected by the array were recorded and processed by the 32-kwords computer system. At present the system is available for analysing the source location and Richter's scale of each event and for visualizing the distribution of seismic foci and released energy at any mining stage. The magnitude distribution of events can be regarded as a comparable index of the seismic activities among mining panels. An analysis of the spatial density distribution of seismic energy in the mining panel can be useful to distinguish a highly stressed zone from stress released areas. The energy released curve or the rate of energy release determined from seismic data is also a good indication of the seismicity.

Jan 1, 1980

By Gillies A. D S, Lee A. H

The major operational objectives of a mine water resource management system (WRMS) are to supply the water needs of the mine and mill, to minimise disturbance to mining due to rainfall flooding or seepage and to dispose of excess water. Historically, company management have placed a significantly lower emphasis on managing the WRMS as compared to managing production. Changing Government legislation concerned with the disposal of water from mine sites is, in many cases making mining companies look more closely at how they manage their water. For example, within the next few years it is likely that prior to mining approval by the Government, mining operations will have to submit water management plans/budgets and contingency strategies in addition to operational plans. While the formulation of a comprehensive water management plan/budget is an additional cost to the company at the mine establishment stage, such plans can be beneficial to the operation in the longer term.The two keys for the efficient design, operation and development of a WRMS are the establishment of written goals which have managerial priority and secondly, access to appropriate good quality data. Managerial priority towards the WRMS will increase as a consequence of the education of mine operators in the benefits to the operation of good WRMS management or less desirably as a requirement to meet Government legislation. The collection of appropriate WRMS data is a more complex issue and to obtain information efficiently and cost effectively relies on the clear definition of the data application.

Jan 1, 1992

By P Cepuritis, G Chitombo a, I Brunton

There is a significant amount of past evidence that links blasting and occurrences of slope failure. Particularly of great concern at Telfer Gold Mine is the effect of open pit blasting on the stability of the footwall slope above the underground portal and the stability of underground structures. For this reason, Newcrest Mining Ltd invited JKMRC to conduct necessary field measurements and numerical modelling with the following objectives:assess the dynamic stability of the footwall slope above the portal; assess the characteristics of current and future blasts in the open pit; and prepare open pit blasting guidelines that will minimise the detrimental effect of blasting on slope stability. To achieve these tasks it was necessary to develop a scaled distance attenuation curve for blast vibrations. In order to validate the developed vibration attenuation curves it was necessary to monitor vibrations from a production blast. Using JKMRC blast design software tools, the vibration of the production blast was also modelled from the blast design and vibration results from single hole blasts. The intention was, assuming that the observed and modelled vibrations were close in terms of frequency and amplitude, to use the software tools to model the vibrations of future blasts and assess their likely effect on slope stability. Numerical modelling of the dynamic stability of the footwall slope was done using the FLAC finite difference code and the UDEC distinct element code. The results of the numerical modelling and of the field measurements of the blast induced ground vibrations were combined into the blast design rules that relate distance between the slope and the blast, charge weight per delay and number of blasts necessary to cause failure of the slope.

Jan 1, 1999

By Dundon P

The Broken Hill Proprietary Company Limited (BHP) is Australia's largest company with widespread commercial interests ranging from steel productin to minerals, oil and gas recovery. While these interests are worldwide, the Company operates or is partner in more than 30 Australian mining ventures. BHP Engineering (BHPE) is the in-house consultant to BHP but is also the largest consultancy in Australia available to general industry. Australian Groundwater Consultants Pty Limited (AGC) is a large, independent consultancy offering specialist services in all aspects of water resources, waste management and environmental engineering, both in Australia and overseas. AGC is particularly well regarded within the mining industry and has a considerable record of providing solutions for mine water related issues. By drawing on the extensive combined experience of AGC and BHP Engineering, this paper will summarize some of the unique ways in which water interacts with and impacts on mining operations in Australia, particularly in matters such as: Slope Stability Drainage and Dewatering Production Cost (Transport, Drilling, Blasting, etc) Water Supply Water Management Tailings and Waste Management Environmental Issues. The paper will also illustrate the cost benefit of providing major engineering works for reduction in total mining cost. It will be shown that, through advance planning and close interaction between outside experts (ie consultants) and on- site personnel, very significant operational cost savings can be made while at the same time achieving a safe and responsible mining environment.

Jan 1, 1988

Builders have been very familiar with iron since ancient times, but because of its weathering characteristics it was relegated to use as a fastening material in unexposed places and bronze became the popular metal for exposed applications. It is of interest that iron nails buried deeply about A.D. 87 at a Roman fortress and carefully covered with clean beaten earth under conditions practically excluding oxygen were found to be almost unrusted 1870 years later. (1) Today, weathering steels, which contain less than 2% of alloying additions, can be used in exposed situations without protection and without experiencing continuous wastage. As we all know the steady access of atmospheric oxygen to the surface of plain steel causes continuous corrosion. Weathering steels, on the other hand, due to their alloying additions develop their own impervious surface layer which limits the access of atmospheric oxygen and effectively limits corrosion. Table 1 shows the chemical composition of a plain carbon steel and a typical weathering steel. Fig. 1 shows what we refer to as direct corrosion - time curves in which corrosion loss is plotted against time of exposure in an strial environment. The weathering steel has a high rate initially which then decreases steadily for about three years, as the stable rust film builds up. This is followed by a practically linear relation where the very low corrosion rate, according to one school (2), is due to a blocking of the rust pores by insoluble complex salts formed from interaction of the oxidation products of the separate alloying elements. The start of the linear region represents a total corrosion loss of only about 2 thousandths of an inch.

Jan 1, 1970