Search Documents

By T J. Howard

At BHP Billiton Iron Ore operations, run of mine ore from the several Newman Joint Venture (NJV) mines is railed in 12 kt rakes to Port Hedland. Rakes are processed sequentially, with the lump and fines components from each rake sampled after crushing and screening. The grade of ore from the individual mines varies around consistently different means. Although a discrete sample is attributed to each rake, the sample contains some material from the following and/or the preceding rakes due to dilution by ore from the neighbouring rakes during the dumping, screening and crushing processes. Individual rake grades at the port are therefore biased according to the mine sources of adjacently processed rakes. Dilution does not affect the grade of the overall NJV product or the accuracy of port stockpile grades; however, it does limit the ability to use port rake grades to review the quality performance of individual mines and provide meaningful lump-fines algorithms and port to mine biases for individual mines, information that is useful when scheduling ore for mining. A non-linear regression model has been used to estimate the average dilution from the preceding and following rakes. It has been shown that the lump and fines samples for 12 kt rakes are each diluted within the Port process with about 8.3 per cent of the sample coming from the preceding rake and about 3.6 per cent from the following rake. This can bias the reported rake grade by up to one per cent iron. The results of this analysis have been incorporated into the daily grade scheduling system to provide more accurate individual mine grade data and consequently better decision making.

Jan 1, 2007

Vaal Reefs Mine annually produces some 75 tonnes of gold. Stoping operations, using a scattered mining method, are conducted on several reef horizons within Witwatersrand Supergroup metasediments of the Klerksdorp Goldfield. Current grades average 7.19 g/t Au over a 133cm stoping width. The reef horizons, of which the Vaal Reef is the most important, consists of 2.9Ga palaeoplacer deposits at the base of low angle unconformities. Typically, a reef comprises a mature quartz and chert conglomerate with a siliceous matrix and intergranular pyrite and carbon. Geologists are primarily responsible for underground mapping and supervising of drilling programs. To a lesser extent they are involved with sampling, grade control, ore reserve estimation, mine planning and rock mechanics. Due to a general decline in grades of gold mines, an escalation of production costs, and with the current weak gold price, it has become essential to improve production efficiencies. Consequently the role of the mine geologist has moved away from that of simply keeping the mining people "on reef'. Greater emphasis is being placed on refining geological models to assist in selective mining of the reef and investigations of secondary reef horizons are encouraged. Exploration within fault losses and re-evaluation of pillars is important, and geologists are becoming more involved with sampling and grade control exercises.

Jan 1, 1990

By F Baars, M Zu, C A. RosiFre, L Lobato

A genetic model for the genesis of high-grade (>65 wt per cent Fe) Proterozoic, banded iron formation (BIF)-related iron deposits such as the Tom Price, Mount Whaleback deposits in the Hamersley Province (Australia), the N4E, N4W, N5 deposits at Carajßs (Brazil), the Aguas Claras, Conceitpo, and Casa de Pedra deposits in the Iron Quadrangle (Brazil), the Donkerpoort West, Kwagas East deposit in the Thabazimbi iron ore district (South Africa), or the Saksagan ore field at Krivoy Rog (Ukraine), needs to take into account the: timing of regional metamorphism with respect to the upgrade of BIF to high-grade iron ore; significance and relationship of the proto-ore to the hydrothermal alteration minerals and zonation and the process of iron enrichment; source and oxidation state of the hydrothermal fluids that caused the iron enrichment; types of geochemical processes that caused the hydrothermal alteration and iron enrichment; and significance of the widespread carbonatisation of the host rocks as a prerequisite for high-grade BIF-related iron mineralisation.We argue that a unifying model for high-grade BIF-related iron deposits cannot, presently, adequately explain the geological and geochemical characteristics observed in these deposits and, therefore, provide two end-member models that take into account the diversity of geological and geochemical ore deposit features. Our discrete model for the genesis of high-grade, BIF-related iron deposits is based on the interpreted tectonic setting, distinct hydrothermal fluid source of, and processes observed in, major BIF-related iron deposits. We divide two end-members: Proterozoic deep fault-magmatic (Carajßs) type, and Proterozoic rift-basin (Hamersley) type.Both end-members experienced varying degrees of deep weathering episodes that effected the hypogene enrichment and, ultimately, yielded the high-grade iron ore mined in many places today.

Jan 1, 2005

By Readett D. J

Soluble salts can be removed from Bowmans lignite by water and acid leaching. The success of the removal of water soluble or acid exchangeable impurities is directly associated with the efficiency of dewatering these slurries. The filtration characteristics of a slurry at its natural pH (4.0) were poor, with a filter cake moisture of 65%. Acid treatment of the slurry at pH2 caused the filter cake moisture content to drop to 61 %. Various oils, oily surfactants and a flocculant were tested to determine the conditions for minimum filter cake moisture. A series of pilot scale filtration tests were conducted on flocculant dosed slurries with and without washing on a horizontal test unit. Moisture contents of 54% were obtained in laboratory testing using high additions of oily surfactant. For the pilot scale test work, moisture levels close to 60% were obtained with low flocculant additions, similar to results obtained in laboratory studies. Removal of soluble salts could be correlated directly to the final moisture content of the filter cake. This process of leaching followed by filtration resulted in the removal of approximately 75% (more than 80% with washing on the cloth) of the sodium chloride originally present in the lignite.

Jan 1, 1989

By Y Li, B Shen, S Zhang

Jointed rock mass is often encountered in rock engineering and its stability has always been a major concern in underground engineering. To analyze the stress characteristics and their variations in jointed rocks, in this study, a new concept of sub-instability stage before rock failure is defined, and a new experimental method is used to investigate interaction between defects and intact rock of the jointed rock mass during the subinstability stage., Firstly, external characteristics of stress and failure mode of the whole jointed rock are investigated systematically by conducting uniaxial compression tests on red sandstone samples with a set of preexisting open flaws of different sizes, and the interactive damage of intact parts and defects in the subinstability stage was further studied. Secondly, rock-like material samples made of bonded plaster blocks were tested and internal data from stress sensor between the strong and weak segments were collected. The transforming processes from independent activity of the individual segment to overall interactive movement of jointed rock before the unstable failure were analysed. The test results indicated that the subinstability stage marked the beginning of interactive failure between the intact rock and defects. In the early subinstability stage, the relatively intact parts bore most of the load in a jointed rock mass, and the defects were damaged firstly which caused high strain around it. The areas of high strain increase rapidly, extending and migrating, causing damage to the intact parts. In the later sub-instability stage, the interaction effect reached its maximum, and a large number of cracks appeared in the intact rock and they propagated and coalesced. Intact parts experienced rapid failure and then the jointed rock failed. The experimental method used in this paper to identify the sub-instability stage could be used to identify failure precursors of jointed rock masses and to develop technology for disaster prevention in rock engineering. CITATION:Zhang, S, Shen, B and Li, Y, 2018. Experimental studies on interactive failure characteristics of jointed rock, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 453–461 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

The rnunber of Cenozoic volcanoes which has already been found in China surpasses 600. An ancient Chinese tourist, Xu Xiake (1587-1641 in the Ming Dynasty), mentioned in his travel notes the volcanoes and hot 'springs in Tengchong, a country of the Yunnan Province, 400 years ago. In 1927, the geologist, Yun Zhanli, expounded generally on the recent volcano distribution in China. In the '70's, China not only accomplished aerial photography and produced topographic and geological naps covering the whole country, but also obtained a new understanding of the geographic distribution and process of development of the Cenozoic volcanoes through Landsat imagery; interpretation and ground verification, together with C14 isotope dating and analysis of volcanic rocks.

Jan 1, 1987

The operators of the iron ore railroads in the Pilbara faced problems of excessive wear between rail and wheels as the tonnage hauled increased in the early 1970's. Joint research projects were begun between Hamersley Iron, Mt Newman Mining and the BHP Melbourne Research Laboratories to study these problems and recommend solutions. The particular problems of wheel rail interaction were solved by asymmetrical profile grinding of the rail and modifications to the machining of the wheels. Rail materials were improved through increasing yield strengths by alloying and by heat treatment. Wheel materials were improved by alloying. The economic benefits of these improvements have been demonstrated by much reduced re-rail requirements and other reduced maintenance costs.

Jan 1, 1986

By J Watson

Electronic detonator technology has been under development for the last two decades. Currently, there are a number of systems commercially available with several others still under development, each with its own unique features. This technology can offer a significant advantage to the drill and blast engineer through their ability to initiate an explosive charge at the æplannedÆ time. This new technology has created huge interest within the drill and blast community and also raised their expectations to produce better blasting outcomes. In many cases, specifications (or even expectations) of desired blast results are not properly defined. Interaction between the input variables (rock mass characteristics and blast design) and results (fragmentation, throw, damage, ground vibrations, etc) and their mechanisms, or relationship to one another, are not very well defined or understood. That is why rock blasting is still considered by many as an art rather than science. With one of the few remaining variables (cap scatter) now controllable, todayÆs blaster finally has the ability to apply science to his trade. Even though electronic detonators are available and becoming more commonly used, current field practices are not always conducive to extracting or deriving the maximum benefit from this new technology. In the authorÆs opinion, the following need to be understood to derive and sustain the maximum value: clear definition or specification(s) of desired outcomes from a given blast; impact of different features in an electronic detonator system (precision, accuracy, flexibility, reliability, etc) and their impact on the desired blasting outcomes; interaction of blast design variables (energy, energy distribution, timing, blast geometry) and their impact on desired outcomes; impact of rock mass variability and quality of blast implementation on the desired blasting outcomes; and critical need to utlilise appropriate tools and systems in order to measure and quantify benefits.In the authorÆs opinion a scientific implementation process is the key to derive the benefits. This paper analyses the industryÆs preparedness to derive the benefits from this technology and proposes a scientific methodology to understand, evaluate and sustain the value from this technology.

Jan 1, 2004

By Finlayson J. F

The advantages of rapid and accurate analyses are becoming appreciated in many industries today and have resulted in a great increase in the number of samples received by their laboratories. This has caused some firms to consider the installation of one or more of the instruments available for analytical chemistry. In this country there are relatively few people with experience of instrumental methods and it is difficult for a firm considering the installation of such equipment to assess the advantages which instruments may give them, and to decide which instruments, if any, will be of most use to them. The object of this paper is to give a brief survey of instrumental methods in the field of inorganic analysis. Instrumental methods of analysis have numerous advantages when used correctly. They enable extremely rapid analyses to be made in many cases, e.g., analysis of refined lead by purely chemical means takes about two days whereas spectographically the analysis can be completed in approximately one and a half hours. The accuracy ofinstrumental methods, generally between 1 and 5%, is higher than most chemical methods for small percentages of impurities. Furthermore, if the instrument can be calibrated against absolute standards the errors are usually random and not biased to one side of the correct result. The sensitivity is high, enabling in many cases the detection and determination of smaller percentages than can be detected chemically. This high sensitivity enables and, in some cases, requires the use of very small samples, and results in considerable savings in reagents, allowing the analysis of considerably more samples without undue loss...

Jan 1, 1951

By B Snook, G Rollinson, R Fairhurst, R Herrington

Nickel laterites constitute a significant proportion of the worldÆs Ni reserves and are considered environmentally friendly alternatives to traditional sulfide resources. Subsequently they are of increasing significance for exploration and production. To be successfully exploited, however, they require an understanding of the relations between mineralogy, texture, grade and recovery. The development of automated quantitative mineralogy can aid in the characterisation of the ores to help improve extraction and processing methods. Recent developments in hydrometallurgy have resulted in relatively straightforward recovery of Ni in silicate (saprolite and smectite) ores. However, the extraction of Ni from limonitic ores is more complex. It requires a detailed understanding of the iron-hydroxide species and other, potentially interfering, oxide and hydroxide compounds. Particularly the relations between the Ni-bearing goethite and Mn, Al and Cr may adversely affect the economic prospects of an ore. Manganese can adversely affect the selective recovery of Ni and Co from solutions but has also been highlighted as a significant potential by-product (cf, Zhang and Cheng, 2007). Aluminium hydroxides can be significant acid consumers leading to an increased expense of extraction (Johnson, Cashmore and Hockridge, 2005). Chromite is resistant to acid attack, but chromium in goethite may adversely affect the dissolution leading to a retention of Ni (McDonald and Whittington, 2008). This study presents an investigation of oxide and hydroxide species in laterites using QEMSCAN« EDS/SEM-based automated quantitative mineralogy. Samples were collected from Turkey (¦aldag), Albania and the Philippines. Particular emphasis has been placed on the development of a quantification for Ni-poor and Ni-rich goethite.

Jan 1, 2008

In a previous paper in these Proceedings(l) it was shown from a study of the bore'logs and analyses then available, that the brown coal seams of the Latrobe Valley areas show progressive changes in composition with increase of stratigraphic depth, equivalent to a rise in rank: These changes appear as:(i) An increase in ultimate carbon and hydrogen, calculated on a dry, ash-free basis, and(ii) An increase in calorific value, calculated on the, same basis, each of the order of 1% per 100 ft. of depth, and(iii) A decrease in moisture content of the order of 0.5% to 1.0% per 100 ft. of depth. The decrease in moisture content was found to be less regular than the other changes. In some bores the moisture content remained more or less constant throughout a single seam, or fluctuated slightly, decreasing stepwise on passage to the seam below.It was noted that individual analyses within a bore showed irregular fluctuations, tending to mask the general trend in composition change. This was particularly so for the moisture content, which had been determined for 10 ft. lengths of core, whereas the other components were determined for 50 ft. lengths of core. Averaging of the moisture contents over 50 ft. lengths reduced the masking effects of these irregularities. The suggestion was made that these irregularities arose from variations in the relative proportions of pollen, resin, wood (lignite) and woody attritus composing the core. Such variation in the coal seams has since been established in some detail for the...

Jan 1, 1948

S. A. Tomich (Consulting Geologist, Perth) : I would like to commend Mr. Haycraft on his presentation on the economic geology of the North End of Kalgoorlie. This is an intriguing area which is in the Kalgoorlie field but not of it, inasmuch as it is separated spatially from the main Golden Mile by the Golden Pike Fault. Mr. Haycraft has stressed the differences-the mineralogical and structural differences of economic significance between the two areas.I would like to ask whether he is satisfied that the lithological sequence in the North End is the duplicate of that in the main Golden Mile area irrespective of the postulated effects of erosion, and more specifically whether there is any chance that the quartz-dolerite-greenstone of the North End may be in any way dissimilar from the quartz-dolerite-greenstoneof the Golden Mile which is tellurude bearing.J. A. Haycraft: In relating the quartz-dolerite in the Hannan's North-Mount Charlotte area back to the Golden Mile, we find some quite close similarities. Although the rocks are similar they are not necessarily one and the same.At Mount Charlotte we have three varieties of dolerite- a coarse-grained gabbroic dolerite on the eastern side of the orebody, the host rock medium grained and on the western side, a fine grained dolerite. Further west we have an amphibolitic variety of quartz dolerite.Recent drilling south of the Golden Pike fault on the Enterprise No. 20 level had indicated a remarkably similar sequence of rocks. We drilled west through a wide section of medium grained rocks into a fine grained rock and then into amphibolitic quartz dolerite before intersecting the Golden Pike fault. Williamstown dolerite was located west...

Jan 1, 1965

The torsion test is considered as the best test used when the part is subjected to static or dynamic torque. Many published papers have investigated the torsion of non-heat treated metals. However, very few published papers dealt with the torsion behaviour of heat treated metals. The aim of this work was to study the effect of heat treatment on the torsion behaviour of steel alloy (AISI 01), which can be used for manufacturing small and medium drills, taps and reamers. The diameter of specimens used was 15 mm. The metal used was heat treated under different conditions, then torsionally tested. The results of torsion test were divided into two groups: results obtained during elastic limit from which the shear stress, shear strain and modulus of rigidity were calculated, while from the results obtained during plastic limit the plastic depth was calculated by applying derived equation when the angle of twist was more than yield value. The results obtained indicated that the value of hardness alone is not sufficient to establish heat treatment conditions. Rather, it was found that the determination of plastic depth together with hardness can help in the establishing of the optimum condition which was hardening temperature of 820¦C, hardening time 20 minutes and tempering temperature 220¦C. This condition produces hardness of 60 HRc and plastic depth of 2.5 mm.

Jan 1, 2003

By J Tuma

Technical measurements are an integral part of research and development of new technical devices. Now they are also an integral part of production too, especially as a part of quality control systems. More new problems started with they applications up, like storing and following preservation of big data files. Many problems are also with processing of the measurement results, especially to be up to standards of ISO 9000 normative. It includes basic data about the measurement (structured data) and measurement outputs (huge data streams). Using database systems looks as good idea, because of structured measurement data and they processing. They were developed more concepts of database measurement system support during the research project MSM 272300012. It was decided to develop specialised measurement systems, on the base of experiments and experiences with they use in operating conditions. It proved to be wrong to develop general system, because of compound operating and long response of the system. And it is not possible to use these systems for mass production systems. The problem of data storing is not as easy to be answered, because of dependence on used technical devices. During realisation the measurement system for gearbox noise measurement are data stored to the database, because used analyser system PULSE (Brnel and Kjµr Co) is open structure and can cooperate with other software systems. Anyhow the data streams are not longer (after compression) than the Memo data type, in practical use increases the data file too fast (about hundreds MB daily). Therefore we must include a special supervisory system for administration and creating data files to the system. Nevertheless the used system MS-Access supports data files up to 1 GB, for practical application is better if the file size do not exceed the capacity of CD-ROM disc.

Jan 1, 2003

It has become increasingly clear in recent years that human kind has developed the capacity to alter the environment of the Earth on a global scale. The changes are often subtle. This is particularly true in the case of stratospheric ozone. Ozone is produced primarily in the stratosphere, at altitudes in excess of 20 km, initially through the action of ultraviolet sunlight dissociating molecular oxygen. According to theory as it existed up to a few years ago, ozone is removed mainly by reaction with atomic oxygen. In the unperturbed environment, this reaction proceeds both directly, and by paths catalyzed by trace quantities of nitrogen radicals. Molina and Rowland [Nature, 249, 810, 1974] pointed out that decomposition of industrial chloroflurocarbons could in-troduce an additional source of radicals to the strato-sphere. Chlorine radicals are even more efficient than nitrogen in catalyzing recombination of oxygen atoms with ozone; models suggested that we might expect reductions in the vertical column density of ozone of as much as a few per cent over the next several decades. A reduction in ozone of x¦/a, by increasing the flux of ultraviolet sunlight reaching the surface, was predicted to result in an increase of about 2x% in the number of cases of skin cancer, with other less well defined impacts on the non-human environment for life.

Jan 1, 1990

By B Washington, A Campbell, R Taylor

A sampling and measurement program was undertaken on the reaction shaft of the Olympic Dam copper flash smelting furnace. The object of the work was to provide information to validate a mathematical model of the burner and reaction shaft. Samples and measurements were undertaken through the burner inspection ports and the South East (SE) shaft sampling port about half way down the reaction shaft. Samples were collected to enable the calculation of particle loading of shaft gases, or sizing and chemical analysis of the partly-combusted feed, and the preparation of polished sections. Measurements were made of the temperature and sulfur dioxide content of the atmosphere, as well as plume velocity.To implement the program it was necessary to design and construct the following specialised items of equipment. For use at the burner inspection ports: a cup sampler for obtaining samples below the burners (temperature, solids loading and samples for characterisation).For use at the SE shaft sampling port and also at the settler level: trough sampler (plume definition and samples), isokinetic sampler (used as a velocity probe in this work), temperature probe (temperature traverses across the shaft), and sulfur dioxide probe (SO2 measurements across the shaft).The design of the sampling and measuring equipment is described, and examples are cited of the types of information obtained. The problems arising from working in a hot environment with molten or sticky particles are discussed.

Jan 1, 2005

pNumerical modelling has been used to examine the relationship between the results of two commonly used methods of assessing the propensity of coal to spontaneous combustion, the R70 and Relative Ignition Temperature tests, and the likely behaviour in situ. The criticality of various parameters has been examined and a method of utilising critical self-heating parameters has been developed. This study shows that on their own, the laboratory test results do not provide a reliable guide to in situ behaviour but can be used in combination to considerably increase the ability to predict spontaneous combustion behaviour./p

Jan 1, 2005

Location & Permit Status Three major Mesozoic Tertiary basins exist along the continental shelf area of southeastern Australia, known as the Bass Strait area. They are the Gippsland (east of the longitude of Melbourne) Otway (west of Melbourne) and the Bass (underlying central Bass Strait between Victoria and Tasmania). The total area, both onshore and offshore, is approximately 100,000 square miles. In March 1960, the Broken Hill Pty. Co. Ltd. acquired exploration title to the continental shelf areas of the Gippsland, Bass and Otway basins from the States of Victoria and Tasmania. The title to that part of the Otway Basin in South Australian waters was granted in July, 1961. Other exploration permits, being 8 miles wide in Gippsland, held by Woodside :E.) Oil Co. N.L., and 15 miles wide along the southwest coast of Victoria, held by Mobil-BP-Interstate Oil (Frome-Broken Hill Co. Pty. Ltd.), were in existence prior to granting the B.H.P. title. Subsequently, Shell, B.H.P., Esso and Magellan have been granted title to the remaining areas of the continental shelf in the basins under discussion. In three separate agreeme negotiated between 1964 and-1966, Esso obtained farm-in rights to B.H.P.'s Gippsland, Bass and Ott' Permits.

Jan 1, 1970

By J P. Hsi

Recent increase in the development of underground space in urban areas in Australia has included soft ground tunnel construction. The ground movements associated with soft ground tunnel construction may present risk to other existing and proposed structures in the nearby vicinity. Much experience has been gained both in the UK and Asia in recent years in the engineering evaluation of this risk. The paper presents a procedure to assess these aspects of soft ground tunnel construction with reference to recent projects.

Jan 1, 1999

The principles and practical applications of the Mogensen Sizer are examined, with particular reference to the experiences at Coal Cliff Mine, New South Wales. The Mogensen Sizer has proven to be a worthwhile alternative to conventional screening. It has the flexibility and capacity to offer a useful sizing tool, particularly in areas of confined space. It is simile in design and 1 in construction.

Jan 1, 1984