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All large open pits in Australia have been mined, or are planned to be mined well below the local water table. This raises several issues that impact on mine safety, mining costs and regulatory approvals. Some pits will be æwetÆ, where they are mined through permeable horizons and where there will be measurable groundwater inflows. These will require some form of dewatering. There may also be some difficulties in the disposal of excess water. Other pits, may be ædryÆ, where they are mined through impermeable material and there are no measurable groundwater inflows but where there are stability issues related to hydrostatic pressures within the pit walls. These may require some form of depressurisation. Some pits are a combination of both. Effective management of groundwater inflows and groundwater related stability issues and the development of cost effective and environmentally acceptable dewatering and depressurisation systems requires an understanding of site specific hydrogeological conditions and practical experience in what works best for different conditions. The presentation will include an outline of the key hydrogeological factors that impact on large pits, practical methodologies for achieving dewatering/ depressurisation, and some case studies from the Goldfields, Pilbara and North Queensland.

Jan 1, 2003

By Bagley A. S

The accuracy and precision of rutile analyses are discussed. Comparison is made between the wet chemical and X-ray fluorescence spectrographic methods of. estimating Ti02 in commercial rutile. Various allotropes of 'I'i02 are identified by diffractometry and a comparative analysis of the coloured varieties of rutile is given. For X-ray fiuorescence . analysis, specimen preparation is critical and sample grinding and pressures. for pellet making are discussed in detail.Cellulose bonded and backed pellets are shown to be subject to relaxation with increasing age.INTRODUCTIONTo date much of the analytical work on commercial samples has been done by wet chemical methods.This led to various discrepancies in results, which are of particular importance when certificates must be issued for overseas shipments. The present work reviews the nature of rutile and compares the results of Ti02 estimation by wet chemical methods and those obtained by X-ray fluorescence spectrographic analysis.In the rutile industry the results from different analysts and even those from the same analyst are not always consistent. To the analytical chemist this should not be surprising.Fairbairn (1951) showed the results obtained from 34 different analysts on a specially prepared sample of granitic rock. It is of some interest to note that the Ti02 content as determined by the 34 analysts using unspecified methods ranged from 0-17 per cent to 0·30 per cent. Fairbairn (1953) found that1. replicate analyses from the same analyst give a high order of precision,2. analyses by different analysts using the same procedures give reasonable precision, and...

Jan 1, 1965

Study on Rational Process Flow Sheet for Beneficiating Low-Grade Cu, Mo, Bi, S, W Polymetallic Ore

Sep 13, 2010

In Australia we usually define "resource" in purely material terms, and rarely relate it to intellect and human capacity. We look at the sheer abundance of our natural resources and are satisfied with the feeling that we don't really need-to rely on using our brains. Certainly our country is fortunate to have the mineral resources it does, but in many ways Australia's worst enemy is its "lucky country" syndrome because we tend to underutilise the great resource we have in the capacities of our people. Raw material exports will undoubtedly continue to contribute a major share of our export revenue, but to harness the riches our country has to offer most effectively we need the vision and planning necessary to bring together our material and human resources. There is a need not only to find, exploit and process our minerals economically, but to turn as much of our mineral wealth as possible into high value products before it leaves the country. In particular we must use our brainpower if we want to maximise economic benefit from and political influence over the strategic minerals which leave our shores. In the past we have been successful in finding and exploiting minerals because our mining industry has been in the forefront of private sector research and development. But if Australia is to have an advantage over other mineral rich countries in insulating itself from the effects of cyclical swings in commodity prices, then the future of the industry must lie even more in technological sophistication rather than depending. on such considerations as size and location of mineral deposits. To survive, our mineral industry must have the foresight and resourcefulness to make its own luck. There are two keys to increased efficiency in exploration and production and in further processing methods: enhancement of the skills of the workforce and continual improvement of R&D.

Jan 1, 1986

In dealing with the pulverization and treatment of auriferous ores, it may be stated that there is not one system of treatment applicable to all classes. In the southern portion of New Zealand the ores generally contain free gold, with scarcely any impurity that is, it is found in an almost pure state, without any alloy, and its dissemination amongst the matrix is generally in tolerably coarse particles. The only difficulties the mill man has to contend with, are the economical concentration of pyrites, which in some of the lodes are rich in gold, and the extraction of the gold the pyrites contain. In some of the lodes there is what may be termed float gold, that is, the particles of the precious metal are so finely divided that it passes over the quicksilver tables, and, unless there are other appliances for saving it, this class of gold is entirely lost.Indeed it is only within the last five years that any attention has been given, in the southern portion of the colony, to saving the fine gold that has passed the amalgamating tables. In the North Island the ores are very complex there are scarcely two mines, although they may be adjoining each other, where the bullion is of the same character. On every field the gold is alloyed with silver', and in combination with other metals and mineral substances, such as copper, zinc, antimony, galenfl, iron, sulphur, arsenic, etc., and, in some instaaces, cinnabar, as in the case of the Champion lode at Tui Creek, Te Aroha. Ores of this class are extremly difficult to treat satisfactorily.

Jan 1, 1903

By M Dunglison, P M. Cameron

Simultaneous mass-balancing of a mineral processing flow sheet results in adjustments to each data point that reflects the accuracy and precision across the full set of data. In this way, all the good work that goes into designing the sampling and analysis protocol for each sample point is leveraged in order to produce a æbetterÆ set of balanced numbers for every sample point in the circuit. Few operating plants employ whole of circuit balancing techniques to produce reported operating results. This situation is changing with the application of mass balancing technology which utilises redundant data for production accounting and metal reconciliation from product to ore source across multiple phases and multiple time periods. Mine and plant data can now generate credible information to improve productivity. Mine and plant personnel can now use consistent data sets for review and planning. Decisions based on balanced data can be made quicker and with increased confidence.

Jan 1, 2005

Mineral processing is at the hub of the exploration-mining-metals production system. Because of the large volumes of material processed, incremental technology investments can pay off better than for other parts of the system. However, much of mineral processing remains a 'black art', because we are behind in investing in modem technologies. Consequently, we have one of the best opportunities to improve efficiency and competitiveness through the application and transfer of technologies that have already been developed for other industries. The reluctance of minerals companies to place priority in our area is not because we lack new ideas; our senior management has not been convinced, based on our previous results, that such investments will pay off as well as other investment opportunities competing for the same resources. The key is the proper establishment of technology strategy and more effective transfer of technology. The presentation will identify the failure mechanisms of technology transfer and will present a model for improving the success rate, a prerequisite for raising the priority of mineral processing investment. Topics emphasised include strategy formulation, human resources planning, and total quality management principles applied to improving technology transfer.

Jan 1, 1993

By B Smith, R Gelson

Springvale Colliery is an underground longwall mine situated approximately 10 km north-west of Lithgow in the western coalfields of New South Wales. Following a full-scale review of the mineÆs ventilation system in mid-2010, it was clear that the mine by early 2013 would become ventilation constrained as a result of the increasing size of the mine workings, the predicted worsening tailgate conditions and plans to introduce a fourth continuous miner unit. This realisation led Springvale to embark on a major upgrade of the mine ventilation system that would meet short-term and life-of-mine (LOM) requirements.Included in the upgrade project was the installation of a new high pressure centrifugal main exhaust fan that is capable of overcoming the high resistances imposed frequently on the circuit by restrictions in the tailgate airway. The new fan featuring a 2.5 MW motor is designed to be capable of operating at a quantity of 250 m3/s at a pressure of 7.9 kPa, a substantial improvement over the previous system, which had an operating duty of approximately 145 m3/s at 1.9 kPa. The new fan is of a centre hung design and features a backup diesel motor to maintain ventilation in the event of a power outage.Structural engineering analysis determined that under the operation of the new main fan the existing standard of ventilation control devices (VCDs) at Springvale would not be adequate to withstand the increase in differential pressures. As such, an upgrade of critical VCDs was undertaken utilising a novel high flexural strength (9 MPa) shotcrete and thin spray-on liner, which help serve to safeguard the structural integrity of the appliances and prevent increased leakage as roadway conditions at VCD sites deteriorate over time (a serious problem in many areas of the workings at Springvale).In addition to the main ventilation system upgrade, a separate upgrade focusing on improving development face ventilation was also undertaken. This upgrade included the purchase of two high capacity (22 m3/s) variable inlet vane (VIV) auxiliary fans to facilitate comfortable development face ventilation.The upgrade of the mine ventilation system at Springvale has been three years in the making, but has removed a major business risk in that it has afforded mine planning and operational flexibility (a fourth unit can now be introduced) for the LOM, and importantly provided unprecedented levels of comfort to operators at the working faces where previously ventilation and heat issues were frequently reported. The impact of this on the morale of the workforce, and hence their output, should not be underestimated.CITATION:Gelson, R and Smith, B, 2013. Life-of-mine ventilation system upgrade at Springvale Colliery - A case study, in Proceedings The Australian Mine Ventilation Conference , pp 79-86 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By D Chalmers, C R. Ward, B B. Beamish

Coal workers’ pneumoconiosis (CWP) has re-emerged as a major concern in the Australian coal mining industry. Harmful effects from coal dust inhalation have been well documented, but the underlying causes and mechanisms of CWP are still debatable. Research conducted in the USA has proposed a plausible link between the presence of pyrite in coal and the prevalence of CWP. Reactive pyrite in coal oxidises under ambient mine conditions to produce various iron sulfate minerals such as melanterite, rozenite, roemerite and szomolnokite. Rapid reaction rates are promoted by the form (size and morphology) of the reactive pyrite present, which provides both increased surface area and increased porosity for easy air access to reaction sites. The products formed from reactive pyrite oxidation are often needle-like crystals with thicknesses in the order of 1–2 µm (eg melanterite and rozenite) and prismatic crystals with thicknesses less than 5 µm (eg roemerite) have been recorded. The densities of these minerals are significantly less than quartz, which makes them prone to becoming airborne with the normal coal dust. In fact, the mix of these mineral salts is commonly referred to as ‘fairy dust’ by mine workers due to the way they can become entrained and sparkle in the mine ventilation air, particularly if they occur in the upper part of a seam that is forming a coal roof. Examples are presented of the various products of reactive pyrite oxidation found in three Australian coal samples, which provide evidence of the physical and chemical mechanisms that would support the USA findings, particularly in terms of a source of bioavailable iron leading to increased inflammatory stress response.CITATION:Beamish, B B, Ward, C R and Chalmers, D, 2017. Products of reactive pyrite oxidation in the mine environment – implications for coal workers’ pneumoconiosis, in Proceedings Australian Mine Vent Conference 2017, pp 87–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By N Kawashima, R St C Smart, A M. Robertson

This paper focuses on a case study at a base metal mine located in a tropical semi-arid area of Western Australia (WA). It is demonstrated that understanding the geochemical nature of the mine tailings forms an integral part of innovative management strategies developed throughout the life-of-mine (LOM) when planning for mine closure. The tailings are currently stored at an above-ground valley fill tailings storage facility (TSF) and one option for long-term management under consideration is leaving the tailings in situ at mine closure and covering using the concept of an enhanced æstore and releaseÆ cover system.Extensive geochemical and mineralogical studies have found that the geochemical behaviour of the tailings in the TSF is significantly more benign than initially predicted. The sulfide content of the tailings is primarily pyrrhotite, which can be acid-forming, acid-neutral or acid-consuming depending on a number of factors including redox conditions. Tailings pore water at depth is pH neutral with excess alkalinity, low concentrations of dissolved metals and elevated sulfate concentration.Recent geochemical tests on tailings samples indicate that a reduction in the acid potential and a corresponding increase in the neutralising potential of the tailings, through partial removal of pyrrhotite at the ore processing stage, has the potential to further reduce the long-term risk of potential impact to the environment from any TSF seepage. The current work program investigates whether partial removal of pyrrhotite is feasible and secondly, whether this approach is necessary to produce a significantly better outcome at mine closure.CITATION:Robertson, A M, Kawashima, N, Smart, R St C and Schumann, R, 2012. Understanding tailings geochemistry - Continuous learning and innovation when planning for mine closure, in Proceedings Life-of-Mine 2012 , pp 287-292 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By G S. B Karunatillake

Following a pre-feasibility study, Mount Isa Mines commenced a feasibility study on the deposit of the George Fisher Mine in May 1997. Board approval was granted in May 1998 to construct a 2.5 million tonne per annum mine and to upgrade existing concentrator and smelter facilities. The world-class George Fisher zinc-lead-silver deposit is located approximately 22 kilometres north of the city of Mount Isa, in north-west Queensland and is 2.6 kilometres north of the existing Hilton Mine. It will be a large-scale underground mine, sustaining a profitable zinc-lead-silver business in Mount Isa for at least ten years. This paper will outline the details of the mine that was developed during the feasibility and design phase. It will include a description of the mining methods, ventilation, fill, ore handling, services and infrastructure. The utilisation of existing assets and the development of innovative ideas were essential to the successful economic development of the George Fisher Mine.

Jan 1, 2000

By G M. Taylor

The application of high technology to monitor and control fire life safety, critical functionality in tunnels and underground spaces generally has progressed at an ever accelerating rate over the past decade. Today these systems comprise some of the most complex and little understood aspects of the tunnel/underground facility construction industry, with this area being perceived as high risk comprising impenetrably complex ‘black box’ technology covered in blinking LEDs. This paper will seek to explode some urban myths and common misconceptions associated with such systems, providing its intended audience with a review of what all this technology comprises and where the real risks lie in its delivery lie.The author contends (and looks to support such contention via this paper) that by applying baseline project and risk management processes to the procurement of this widely misunderstood black box technology, the quality of the final outcome can be much improved, driving innovation, reducing both cost and significantly mitigating delivery risk.CITATION:Taylor, G M, 2014. Procuring control and intelligent traffic systems for major new build projects – avoiding pitfalls and maximising value, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 113–120 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By C Li, D O’Dea, R Moreno-Atanasio, T Honeyands

The behaviour of iron ore granules in the feeding process of sintering is significantly influenced by the material properties of the granulated mix. Therefore, the measurement of key material properties of the iron ore granulated mix is indispensable prior to the simulation of the sintering process based on the discrete element method (DEM). In this paper, three key property parameters of the iron ore granulated mix, apparent density, elastic modulus and rolling friction coefficient, were measured in laboratory-scale experiments. For different sintering processes, the moisture content of the granulated mix normally varies according to the specific requirements for granule size distribution and operating conditions. Therefore, understanding the effect of moisture content on the property parameters of iron ore granules is very helpful in accurately determining the property parameters for DEM simulation work. In this paper, six groups of iron ore granule samples with six levels of moisture contents were prepared through granulation and the trends in apparent density, elastic modulus and rolling friction coefficient with the increase of moisture content were plotted and analysed based on the measurement results. The results show that as moisture increases from 6.9 per cent to 9.1 per cent, the apparent density decreases from about 3000 to 2800 kg/m3. With moisture increasing within the same range, the elastic modulus first decreases from over 200 MPa to below 100 MPa and then reaches a relative constant value of about 40 MPa at higher moisture contents. Rolling friction coefficients are measured using two methods with both indicating a similar trend, with the rolling friction coefficient first decreasing and then rising as moisture increases from 6.9 per cent to 9.1 per cent. The relationship between µr and µ’r is assumed to be similar to that between static and dynamic friction coefficients.CITATION:Li, C, Moreno-Atanasio, R, O’Dea, D and Honeyands, T, 2017. Variation in property parameters of iron ore granulated mix with moisture content, in Proceedings Iron Ore 2017, pp 79–84 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By E Widzyk-Capehart

The mines of the future can be envisioned as complex, large-scale technological systems being operated remotely from few centrally located (major cities) operating centres and skeletal crew stationed at the site. These systems will require remotely located human operators to constantly adapt to new and unforeseen system and environmental demands. In addition, the remote operators will need to match system properties to the changing demands and operational conditions, ie must be able to handle the ‘non-design’ emergencies, because the system designers would not have been able to foresee all possible scenarios of failures and provide automatic safety devices for every contingency. Therefore, it is highly important that the operators’ job, which involves problem solving and decision making at the workstation level, is facilitated by the proper interface designs. This paper argues that decision support systems and thus human-system interfaces for the mines of the future should be developed based on the principles of human-system integration that take into account human information processing and cognitive abilities. The information presented to the operator must support the operator in taking appropriate action through a human-system interface designed according to scientific principles of User Centred Design. A case study is presented where an iterative design process was used by CSIRO researchers as an evaluation method involving users (control room operators) at several stages of the user interface design in order to correct any design inadequacies as they emerged. This process allowed the designers to identify any usability issues before the user interface was fully implemented, which subsequently enabled the control room operators to easily adapt to the new interface and carry out all designated tasks in a timely and effective manner.

Nov 22, 2011

By N Madani, S Abulkhair, N Morales

Conventional geostatistical algorithms cannot reproduce bivariate complexities such as inequality constraint, nonlinearity and heteroscedasticity. Poor reproduction of these features may decrease the accuracy and reliability of mine planning results. For example, it is not unusual to have an inequality constraint between primary and disturbing elements in a metalliferous deposit. Implementation of traditional methodologies for such complex data sets can lead to the incorrect reproduction of a bivariate relationship, which will affect the validity of NPV results. In this paper, an iron data set containing iron and silica grades with an inequality constraint between variables is introduced as a case study. This study proposes an algorithm based on a hierarchical sequential Gaussian cosimulation integrated with inverse transform sampling. The proposed methodology considers the linear inequation between two variables in the hierarchical cosimulation process to reproduce an inequality constraint. As a comparison, conventional sequential Gaussian cosimulation is also applied to the same data set to demonstrate the difference in bivariate relationships from both models. Unlike the proposed algorithm, the conventional cosimulation cannot reproduce an inequality constraint and slightly overestimates silica grades. The modelled realisations are then used to assess the uncertainty of a plan and generate a stochastic strategy that adapts the destination of the blocks depending on the scenario. Two-stage stochastic long-term production scheduling takes extraction decisions using average information (ie e-type model) and ore/waste destinations based on geostatistical realisations. As a result, the proposed strategy is closer to the upper bound, highest possible NPV for each realisation, than to the lower bound, deterministic strategy that does not manage the risk of sending extracted material to wrong destinations. Furthermore, Comparing production schedules resulting from proposed and conventional geostatistical methodologies shows the importance of inequality constraint reproduction and more accurate long-term mine planning.

Nov 8, 2021

By R Moller

Reconciliation at large iron ore operations is a complex and time- consuming process. Often the volume of data and the large range of different stakeholders makes the process almost impossible. Up until recently geologists and engineers at these operations would spend hours cutting and pasting data in and out of monster spreadsheets, diligently comparing how resource/reserve models, grade control and survey pick-ups compare to what was actually produced. In 2003 the Sishen Iron Ore Mine in South Africa broke this cycle by implementing SnowdenÆs Reconcilor software. The implementation of a dedicated reconciliation system required a number of existing practices to be changed, with the involvement of stakeholders right across the mine. Data sources had to be clarified and validated, terminology had to be standardised, processes needed to be documented and some methodologies needed to be updated. This was a task that required significant effort by Kumba personnel so that the system could be successfully implemented. This paper provides a case study of the reconciliation system implementation at Sishen. It is a story of an operation that evolved from using a number of fragmented reconciliation processes to using a unified automated system. This paper outlines the key estimates and measurements that are used for reconciliation, details the characteristics of an automated web-based information management system to facilitate the process and provides some insights about the benefits that have been gained though the use of a rigorous reconciliation process.

Jan 1, 2005

The Jundee gold mining operation is located in the Western Australian Yandal Greenstone belt. Jundee is a mature operation encompassing multiple and complex underground ore resources, dwindling open pit reserves, large surface stockpiles, small satellite resources and two near-mine but stand alone process plants. The imminent completion of continuous open pit mining and the associated drop-off in total mill feed precipitated a review of the strategic mine plan and development of options that would optimise the exploitation of the remaining mineral resources and the utilisation of the existing plant and infrastructure.An initial review of the strategic decisions to be made, available options as well as the quantity, complexity and co-dependency of the strategic variables quickly led to the conclusion that an Operations Research style modelling approach would be appropriate. An 'off-the-shelf' program engine by the name of WHATSBEST! (LINDO Systems Inc.) was chosen on the basis of price, reputation and ease of use. The model was formulated with the unknown variables (being the ore mining rates) expressed as a proportion of the maximum achievable ore mining rate from each source. Costs were defined as variable or fixed, with this definition being a key aspect of the modelling process. The critical application of the model was in determining the optimal extraction rate of ore, the destination (ie Jundee or Nimary mill) and the sequence of extraction of each ore source that maximized the cash flow of the operation. The program was designed to be able to quickly derive an optimal result from the many variables, replacing the previous laborious iterative process of arriving at an acceptable answer by means of several large and static spreadsheet models. This paper presents the process of selection, formulation, application and scope of operation of the turn-key linear and non-linear program strategic model now used as part of the Jundee Operation strategic decision making process.

Jan 1, 2002

SEVERAL serious accidents, which had occurred owing to the platman leaving the plat without first withdrawing the "chairs" from the shaft, set the writer scheming to devise a mechanically operated system which would obviate such accidents and be "fool-proof". It was obvious at the outset that some means of indicating to the engine-driver by the movement of the "chairs" themselves, whether they were "in" or "out" of the shaft, was necessary.An arrangement of signalling similar to railway semaphores was considered, but was rejected owing to the difficulties accruing from the large number of communicating wires which would be required down the shaft-viz., 2 for each level. After several experiments, a comparatively simple and efficient electrical system was devised, and which is covered by Commonwealth Patent TO. 10,402.One of the chief features of the apparatus is its simplicity, and its strongest point is the fact that both the engine-driver and platman receive visual indication of the position of the "chairs." The arrangement consists of a miniature coloured glow lamp, one for each level of each shaft compartment, arranged and placed beside the numbers and arrows corresponding to the various levels, on the winding engine indicators. Also a large indicating glow lamp is installed at each compartment in the various levels, in proximity to the levers for operating the "chairs." Upon operating the various levers for the "chairs," an electrical current...

Jan 1, 1909

By M Hitzman, E P. Nelson, J Skarmeta

The Coastal Cordillera of northern Chile hosts the youngest and possibly best preserved iron oxide copper gold (IOCG) belt yet discovered and includes important deposits such as Candelaria and Mantoverde. The spatial and temporal relationships of hydrothermal alteration and mineralisation (Fe and Cu-Au) related to structural and lithologic features were investigated through geologic mapping and petrographic and geochronological studies along two W-E-transects crossing the Coastal Cordillera to the north of Vallenar. The project aimed to determine vectors for district-scale and regional exploration. Along with magnetite-apatite deposits (Central Iron Belt) and manto-type copper deposits, the IOCG deposits are hosted in a N-trending volcano-sedimentary sequence formed in a Jurassic to Early Cretaceous arc/back-arc setting (Sillitoe, 2003; Ramos and Alemßn, 2000). Calc-alkaline plutonic rocks intrude and metamorphose the volcano-sedimentary sequence, and become progressively younger from west to east reflecting a shift of arc magmatism (to Paleocene in the far east). From west to east along the Agua Grande-Chehueque profile, four domains of different economic potential are recognised. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Wylie A. W, Mathew P. J, Eisler P. L

Field studies of the radiations backscattered by iron ores from a 60Co source of primary gamma radiation located in a borehole logging probe have confirmed thatthe P" factor, a ratio of high energy gamma ray intensities to low energy intensities in selected energy windows of the backscattered gamma-ray spectrum, is a valuable measure of grade for sedimentary iron ores of the Pilbararegion of Western Australia.Laboratory studies of model boreholes have shown that variations in borehole diameter and variations in bulk density of the formations have a significant influence on the measurement of P" ratios. If these influences 'are taken into account the mean ore grade in a new blast hole, for instance, can be predicted with a probe of suitable configuration to within 0·8 per cent Fe at the 95 per cent confidence level, while the grade of a single 120-cm split can be determined to within 2·6 per cent Fe. These results were obtained by pooling data from five blast holes covering the range of iron concentrations 20-68 per cent Fe and apply to the mean hole grades 54-68 per cent Fe.Results for two development holes were generally comparable to those obtained from individual blast holes95 per cent confidence limits of ±0·9 per cent Fe for mean ore grade and ± 4·1 per cent Fe for single splits. A greater number of data points is needed before these confidence limits can be further improved.The technique utilized to obtain these results was derived from a "multiband" approach to collection of backscattered spectral intensity data, an approach which permitted selection at the data processing stage of the most statistically significant P" ratios for the type of mineralization encountered in the field. The multiband technique also permitted selection of the most significant of another set of windows in the backscattered gammarayspectrum to measure a newly developed "S-factor", a ratio sensitive to borehole diameter. Another window provided information on bulk density. All these measurements were made with a single pass of the same loggingprobe.

Jan 1, 1977