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By Kelly D, Moore C

The Golden Mile, which has been mined continuously for the past 100 years by both underground and more recently open pit methods, occupies an area of 1.2 km by 4 km adjacent to the city of Kalgoorlie Boulder in Western Australia (Figure 1). Large-scale open pit mining at the Kalgoorlie Consolidated Gold Mines (KCGM) Fimiston operations is currently extracting 7.8 million tonnes of oxide and sulphide ore for a total production of 522 000 oz per annum. The effectiveness of grade estimation techniques at KCGM has been examined with reference to existing 10 m bench sample data from all operating areas within the Eastern Lode System of the Main and North pits. The aim of the study was to recommend practical parameters for grade control estimation. The review included comprehensive variography and comparison of nonparametric estimation methods (Joumel, 1983) such as indicator kriging and probability kriging with ordinary kriging, leading to the development of improved grade control parameters and procedures for both daily quality control and short term mine planning. This paper reviews the geological, statistical, geostatistical, mining and modelling features studied in order to present KCGM's Mining Department with recommendations for improving grade control.

Jan 1, 1994

Fast Adsorption Phenomena at Air/Liquid Interfaces

Sep 13, 2010

By Greenwood J. N

This is the fourth paper in the series on Australian w,ar materials and the work was undertaken as part of the programme for producing hard carbides. It had been intended to determine the influence of tantalum and columbium' carbides in mixtures with tungsten carbide. Owing to other, urgent developments, it has not been possible to proceed with that programme.1. THE PROCESSING OF A TANTALITE ORE(a) The OreThe minerals in which tantalum and columbium most commonly occur are tantalite and columbite. These two minerals are the end members of an isomorphous series of tantalates and columbates of iron and manganese, but in nature the series grade into each other.Some of the best deposits of tantalum and columbium ores in the world occur in the north-west of Australia. Until recently tantalite low in columbium was the only mine~al in demand but discoveries of extended uses for columbium, e.g., addition of ferro-columbium to high chromium I steels inhibits intergranular corrosion (weld decay), have created a demand for columbite low in tantalum as weB. Both of these types of' ore occur in the Pilbara district in Western Australia and most of the ore mined is exported to America after a preliminary grinding and concentration by gravity.A sample from the Bynoe Harbour locality, west of Darwin, was used in this investigation. It consisted of coarse lumps of tantalite with quartz in minor amounts. Cassiterite w.as also present. A recent investigation!l) gave the analysis as:

Jan 1, 1943

The sulphide ore occurring in the North Mine at Broken Hill is of a complex nature, consisting of an intimate mixture of argentiferous galena, marmatite (zinc-iron sulphide), and gangue minerals. A typical analysis of the ore is:Lead 15.2%Zinc 12.0%Iron 5.3%Manganese 0.8%Copper 0.1%Alumina 0.3%Lime 0.9%Sulphur 11.1%Insoluble 53.8%Carbon dioxide 0.3%Undetermined 0.2%Silver 9 oz. per tonTotal 100.0%The metallurgical practice for the recovery of the lead concentrate and zinc concentrate from the crude ore is briefly described in the following pages.(1) COARSE CRUSHING AND FINE GRINDING OF THE CRUDE OREThe crude ore from the mine, containing lumps to the size of, roughly, 10 in. x 8 in., is tipped over grizzlies with the bars spaced 3 in. apart; the oversize gravitating to a...

Jan 1, 1933

By H Benzer

Grinding clinker to finished cement consumes more energy than any other comminution process. World production of cement in 2009 was 2840 million tonnes and the energy required for comminution was 40-60 kWh/tonne depending on the clinker characteristics and the fineness of the finished cement. Machines used include single and multi compartment ball mills, HPGRs, vertical roller mills, centrifugal air separators, V separators, screens and crushers. The circuit most commonly used consists of a closed circuit HPGR followed by a single compartment ball mill and an air separator, and in operation the variables are adjusted to obtain maximum throughput with no loss of quality of the separator fines.A common objective in cement plants is to reduce energy consumption without affecting the particle size in the finished cement and simulation is used as one procedure to achieve this. Models are now available for all the machines commonly used in clinker circuits and circuit optimisation studies using simulation have been carried out in many plants leading to decrease in energy consumption per tonne of cement. In this paper the models used will be discussed briefly and several case studies will be reviewed which will highlight the effect of change in ball size in a two compartment mill, the role of the HPGR in an HPGR – ball mill – air separator circuit, and the use of a high intensity vibrating mill for producing finished cement with high additive ratio.

Aug 8, 2011

By M Lewis, A Cook

This paper is based on the technology and functionality of a Modular Mining IntelliMINE« system which is a real-time decision-making tool. The IntelliMINE« system, incorporating Dispatch, is a fully Integrated Mine Management System. Measuring, quantifying and analysing the performance of mining is considered a fundamental and strategic step towards changing the nature of technical and operational decision-making at the majority of international mining corporations. Successful implementation of electronic data capture devices and computerised tools have enabled many mining operations to improve their competitive position with an improvement in the utilisation of the key assets, mineral resources, capital mining equipment and human resources. Real Time Mine Management Systems are designed to direct the emphasis away from collecting data and focus decision makers on the real issues with well-presented and reliable information. The systems provide a common stream of information to enable senior management, operations, maintenance, technical and process plant staff to make complementary decisions based on reliable, accurate and timely data. The mine asset information tools focus all employees on performance and give them feedback on their area of responsibility. The resulting tangible benefits can be delivered in different forms depending on the mining method, ore type, workplace culture and the current competitive position. Typical areas of improvement reported by system users are:reduction in capital expenditure on mining equipment fleets; more effective planning and budgeting parameters and procedures; increased control over ore-extraction and processing; increased employee accountability and organisational performance; and improved co-ordination between planning, operations, maintenance and processing. These improvements can be delivered in different forms depending on the status of the mine and commodity markets. In times of market oversupply and low commodity prices, the benefits can be delivered to the bottom line in terms of reduced cash costs, reduced capital and operating resources to maintain constant production. In times of market expansion, existing capital resources will be more productive delivering increased production and revenue. Mine management systems have the potential to transform a traditional mine operation into a learning organisation with an improved understanding of the critical performance issues and enable development of relevant strategies to continually identify and eliminate operational inefficiencies. The effectiveness of each strategy and operational change can be accurately monitored and its success (or otherwise) will be quantified. The latest downturn in the world metal prices has forced many mining companies to focus on cost reduction and productivity improvements as a means of remaining competitive. Maintenance represents a significant proportion of the overall operating costs in the mining industry. A structured proactive maintenance approach such as Reliability Centered Maintenance (RCM) can achieve significant cost reductions and productivity improvements. Remote condition monitoring systems are becoming increasingly commonplace and have the potential to identify problems prior to failure. Detection of equipment degradation prior to failure will enable repairs to be scheduled, thereby reducing costs and interruptions to production.

Jan 1, 2000

By J Fewings, T McCredden, S Seet, C Fitzmaurice

"Flotation of nickel sulfide ores are generally constrained by nickel grade and impurity concentrations (notably magnesium and arsenic) in the product delivered to smelters. Being a physical separation process, flotation recoveries and grades are limited by the grade recovery curve of a particular operation, where increasing product grades are invariably associated with lower recoveries. Impurities put further pressure on this relationship, as removal of impurities from the final concentrate is almost always associated with nickel losses.Western Areas Ltd are developing a proposed expansion to its Cosmic Boy concentrator to treat an impurity stream, that is high in nickel and would otherwise report to tails. Through the use of BioHeap® technology Western Areas aims to recover the nickel and discard the arsenic to tailings. This expansion will consist of a biohydrometallurgical plant that leaches the nickel arsenic minerals, removing the arsenic as a stable iron/arsenic hydroxide, while recovering the nickel as a high-grade nickel sulfide product (at approximately 50 per cent nickel). This can then be blended with final concentrate to improve nickel grades and recoveries, while simultaneously reducing impurity levels or used to produce high value products like nickel sulfate.The introduction of a small microbial leach plant may be beneficial to base metal concentrators constrained by impurities or grade.Citation:Fewings, J, Seet, S, McCredden, T and Fitzmaurice, C, 2016. BioHeap® - Breaking the Grade/Recovery Curve for Nickel Concentrators, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 361–368 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

The dielectric properties of practically all oxide and sulphide ore minerals are such that they heat rapidly when irradiated with microwaves particularly at the standard frequency of 2450 MHz. The presence of carbon or low rank coal mixed with the minerals still further enhances the heating rate. Amongst the patented technologies being investigated are: (i) the direct reduction of oxides with or without carbon included in the pellets or briquettes; (ii) microwave precursor heating of composites ahead of smelt reduction; (iii) microwave smelting of ore or concentrate mixtures with carbon, sometimes assisted with oxygen. Microwaves appear to stimulate endothermic reduction reactions as readily as they do exothermic oxidation reactions. Being a method of achieving "bulk" heating, composites or columns of ore-char blends rapidly heat throughout rather than from the outside inwards as in conventional heating. The microwaves of themselves do not generate any gas - the only gases to be cleaned are the products of reaction in the composites or blends, plus the products of oxygen smelting. In the case of sulphide composites, depending on the quantity and type of low rank coal or char present, sulphur may be eliminated, and collected, in the elemental form. Furthermore, reactions seem to take place at lower temperatures than in conventional smelting but no doubt at the "points" where actual reactions are taking place the atomic or molecular vibrations are such as to satisfy the laws of thermodynamics. Examples are given of the production of unusual products of smelting sulphide concentrates and also the alloys produced from refractory minerals such as chromite and ilmenite. The techniques have been used to produce products with as wide a range of melting points as relatively pure tin and tungsten-molybdenum alloys. Special equipment is being designed and evaluated for these new fields of pyrometallurgy.

Jan 1, 1989

By P Hawke, J Hurst, B KrapeP

Hancock Prospecting Pty Ltd (HPPL) drilled two deep diamond stratigraphic holes (ECD0001 and RHD0296) within the eastern Fortescue Valley in the Pilbara of Western Australia. Located south of the Roy Hill Iron Ore project, the holes aimed to define the stratigraphy of the Marra Mamba Iron Formation (MMIF) of the Chichester Range and its south-dipping extensions below recent cover. Previous attempts to define the MMIF of the Chichester Range have resulted in differing interpretations due to the data available at the time.The unweathered MMIF beneath the Fortescue Valley in the HPPL drill holes is characterised by dolomitic carbonate interbedded with stilpnomelane-rich shales, chert and banded iron formation (BIF) with hematite staining. This intersection equates to ~75 m of carbonate-facies iron formation, as opposed to the ~230 m thick oxide-facies BIF and shale sequence encountered south of the Fortescue Valley.Various detailed geological core analyses and interpretations from ECD0001 and RHD0296 were integrated with regional diamond and reverse circulation (RC) holes from across the Fortescue Valley. Interpretation of the data indicates that the eastern Fortescue Valley MMIF represents a thinned thickness sequence of the whole formation. The MMIF of the Chichester Range and Fortescue Valley has gamma logs that correlate strongly in parts to the type section used for MMIF south of the Fortescue Valley. Therefore, the outcropping MMIF in the Chichester Range represents an eroded equivalent of the æreducedÆ thickness MMIF observed in ECD0001 and RHD0296.Data from deep diamond drill holes across the valley, from the Hamersley Basin to the Carawine Basin, were correlated. The correlation shows that the depositional site of the MMIF in the HPPL diamond drill holes is consistent with a proximal ramp setting, in which iron-rich shales wedge up-palaeoslope and shelf-derived carbonate turbidites wedge down-palaeoslope. Not only is it the occurrence of these shales that define the MMIF, but they also determine the northward potential to develop orebodies, as they are the source of iron from which iron-rich oxides and carbonates of metamorphic or diagenetic origin form.CITATION:Hurst, J, KrapeP, B and Hawke, P, 2013. Stratigraphy of the Marra Mamba iron formation within the Chichester Range and its implications for iron ore genesis at Roy Hill - evidence from deep diamond drill holes within the East Fortescue Valley, in Proceedings Iron Ore 2013 , pp 91-106 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By D Morton, G Wallace

"Evolution Mining is the sole owner of the Mt Rawdon open cut operation, located 75 km south-west of Bundaberg in Queensland, Australia (Figure 1). It is a massive, volcanically hosted, low-grade gold deposit that exhibits excellent characteristics conducive to low cost mining and treatment.In 2014, Mt Rawdon began investigating initiatives to deliver higher mill throughputs without any significant capital expenditure or modifications to the existing processing plant. Various studies have shown throughput increases are possible by applying more blast energy, essentially by reducing feed size through blasting and leaving less work for the comminution circuits (Brent et al, 2013; Ziemski, 2011; Workman and Eloranta, 2003).Given that 53 per cent of energy used on a mine site is consumed by the comminution circuit, with only two per cent being consumed by drill and blast (Smith, 2013), it makes logical sense for a mining operation to align their drill and blast with their processing plant. The term commonly used when exploring this relationship is a ‘Mine to Mill’ program.Over nearly 12 months, various blasting options and Mine to Mill methodologies were tested at Mt Rawdon. Throughout the journey, it was abundantly clear that the Mine to Mill initiative is not as simple as making one technical or physical change and expecting an improvement. Rather, true sustainable improvements demand a paradigm shift across both the mining and processing cultures, where all departments are aligned and working towards the one outcome. This true overarching Mine to Mill mentality, enabled by Vistis™ 250 high energy bulk explosive, ultimately led to a sustained increase in throughput and profitability of the Mt Rawdon operation.Citation:Wallace, G and Morton, D, 2016. High Energy Bulk Explosives and Mine to Mill Focus – the Mt Rawdon Story, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 60–69 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By Dippenaar R, Evans T

Twin-roll continuous casting technology is rapidly approaching commercialisation. Fundamentally different than conventional continuous casting, heat transfer and hence solidification during twin-roll casting are governed by the interfacial melt/mould thermal resistance, as opposed to the resistance of the solidifying shell. Under these conditions the interface resistance is predominantly controlled by the melt/substrate wetting behaviour. The very early stages of melt/mould contact are characterised by highly transient heat transfer conditions. The overall melt cooling rates prior to the formation of the first solid are reported to be in the range of 1000 - 50000 K/s with melt undercoolings of up to 300 K. At the points of intimate melt/mould contact the thermal resistance is approaching zero, where cooling rates and undercooling much larger than those reported in the literature are probably occurring. Improved wetting will reduce the energy barrier for nucleation while at the same time increasing the cooling rate of the liquid. Since the overall nucleation rate is controlled both by the rate of cluster formation and the rate of atom transfer to the nucleus, a critical cooling rate will exist above which the nucleation rate is expected to be reduced. Under these conditions, it is possible that the first solid phase to form is a metastable glass which subsequently transforms into a crystalline phase. The implications on nucleation and early growth are also discussed.

Jan 1, 1999

This paper gives an overview of the difficulties associated with determining the strength of hard rock pillars. Although a number of pillar design tools are available, pillar collapses still occur. Recent examples of large scale pillar collapses in South Africa were caused by weak partings which traversed the pillars. Currently two different methods to determine the strength of pillars are used namely, empirical equations derived from the back analyses of failed and stable cases and numerical modelling tools with an appropriate failure criteria. Both techniques have their limitations and additional work is required to obtain a better understanding of pillar strength. Empirical methods are popular and easy to use, but care should be exercise that the results are not extrapolated beyond the range of the data which were used to derive them. An example is the Hedley and Grant formula (derived for the Canadian uranium mines) that has been used for many years in the South African platinum and chrome mines (albeit with some adaptation of the K-value) to design the pillar layouts. Very few collapses have nevertheless been reported and it might even be too conservative an assumption of pillar strength in these mines. As an alternative, some engineers strongly advocate the use of numerical techniques to determine pillar strength. A close examination unfortunately reveals that these techniques also rely on many flawed assumptions. An area where numerical modelling is invaluable, however, is to study specific pillar failure mechanisms, such as the influence of weak partings on pillar strength. In conclusion, it appears that neither empirical techniques nor numerical modelling currently provide a solid basis to conduct pillar design. It is therefore recommended that both these techniques be utilised when confronted with a pillar design to obtain the best possible insight into the problem.

Nov 25, 2010

By S Telford, J Weir

Heathgate Resources Pty Ltd (Heathgate) operates the Beverley Uranium Mine in South Australia, located on the plains between the northern Flinders Ranges and Lake Frome some 600 km north of the state capital Adelaide. The uranium orebody exists in permeable sands within the confined, highly saline Beverley aquifer, approximately 125 m below the ground surface and the uranium is mined using in situ recovery (ISR) technology. The Beverley mine is a highly technologically advanced ISR mine and is operated in accordance with stringent safety and environmental standards. The mine is currently licensed to export 1500 t of uranium oxide (U3O8) per annum. This paper outlines the fundamental differences between ISR operations and the more traditional uranium production methods, such as agitation leaching and heap leaching, where the ore is removed from the deposit, stockpiled, crushed, milled and leached on the surface. Solids tailings from either the mill or the heap are finally deposited in a tailing storage facility. ISR mining differs from conventional mining because the ore remains in place underground (in situ) and the groundwater contained in the ore-bearing aquifer is utilised as the mining fluid. This is achieved by drilling into the deposit and installing wells for extracting and re-injecting the groundwater which is fortified with chemicals. The fortified groundwater (ie mining fluid) flows through the permeable sands containing the orebody, dissolving the uranium. The pregnant mining fluid is then collected and transferred to the recovery plant where the uranium is captured (on ion exchange (IX) resin in the case of Beverley). The barren mining fluid is then re-fortified and recycled to the wellfields. Once mining is completed in a wellfield, the surface infrastructure is relocated to a new wellfield, and the mined-out wellfield is rehabilitated to its original surface condition. A comparison of 'standard' hydrometallurgical plants, heap leach and ISR shows a number of key differences, such as the rate of leaching, the level of control available to the operators, and the type of contact/reaction that occurs. While limited in its applications, ISR mining has proven successful at Beverley and provides another mining and processing method for the production of uranium.

Jan 1, 2008

By M Fishwick Tapia

This paper was prepared and translated from the final report of the investigation into the Codelco Chile Salvador DivisionÆs air blast which occurred in the Inca-West area. In this section of the block cave mine, a stable arch formed covering an area of approximately 15 000 m2 . This zone subsequently collapsed producing a massive air blast. The collapse followed a series of planned extraction activities and occurred on 5 December 1999. This paper discusses the cave back arching event and the measures that were taken in order to induce the controlled collapse. This was to minimise risk to personnel, equipment and installations. The results obtained to date are presented.

Jan 1, 2000

By W L. Jennings

This paper summarises work undertaken to date as part of an investigation into the mineral resources of the proposedNorth West South Island National Park. The area covered by the proposed national park is underlain by many rock types that have undergone a long and complex history of evolution which has endowed it with some of the best potential for a wide range of different minerals in New Zealand. Many of these minerals occur only in this area or in Fiordland National Park.   The first gold-rush in the area occurred in 1856 and followed the discovery of payable gold at Lightbands Gully, south of Collingwood. The miners first focused on the alluvial deposits but soon shifted attention to lode potential. The total historical gold production for the area may be over 400 000 oz (NZ$250 - NZ$295.6 M at 1993 prices).   In addition to gold, a wide range of other minerals have been reported from the area including molybdenum, copper, nickel, zinc, silver, bismuth, stibnite, lead and antimony. The Onekaka iron-ore deposits have produced small tonnages of ochre and iron-ore at various times. Tungsten, platinoids and other metals have been. given only minor attention. The diverse geology of the Northwest Nelson has resulted in the occurrence of many industrial minerals which have been exploited in generally small-scale operations. Aggregate, chrysotile asbestos, clay, dolomite, marble, limestone, dimension stone, rip-rap, talc-magnesite and wollastonite have all been produced.

Jan 1, 1993

By S Grimsey, E Janetzki, J Emery

Floor failure on the longwall face is a complex problem due to the dynamic interaction between the surrounding strata and powered roof supports involving multiple variables. It can also be highly problematic and costly when not well understood as there are significantly less remedies available post event. This was the early experience at the case study mine where significant lost time was incurred due to unplanned delays in the first two panels. To detect and prevent such occurrences is clearly the best approach, hence a tool to predict both floor failure occurrence and magnitude prior to mining was developed. Several parameters were determined as the key drivers for the failure events that had been experienced at this site. These parameters were, in list of influence from highest to lowest, material strength, retreat rate and the presence of water. The parameters were evaluated using a semi quantitative risk rating system ‘Heave Risk’ and given a weighting per their apparent influence. This ‘expert system’ methodology was selected as the use of risk rating systems in underground coal mining is well established. The heave risk model was first applied to previously mined panels. It accurately identified all areas of known major floor heave, with clearly defined areas of low and high risk apparent. The heave risk model was then used prior to mining and evaluated post mining based on observed conditions. It was found to also be highly accurate for prediction. The variability of each parameter and its influence on the overall risk rating is illustrated and discussed.

Nov 29, 2022

A GREAT deal of attention has lately been given to the discussion as to the education required for engineers, and especially for mining engineers. The Institute of Civil Engineers has had a committee's report on it which has come to some interesting and valuable conclusions.The Institute of Mining and Metallurgy had a few years back a very long discussion on the subject, and the subject appears to be one of perennial interest to similar societies. Two recent addresses by Prof. Kernot, as president of the Victorian Instituteof Civil Engineers, are among the most interesting and practical of the contributions to the discussion. Engineers seem to feel either that the coming generation has not the same capacity to benefit by the training that has made themselves what they are, or that such training has turned out in themselves inefficient men, and that they must consequently struggle to obtain a better one for their successors. For not only is there a desire to extend existing instruction to cover the advances of science, but there seems to be a general desire also to make a completely radical change in the methods.It is not necessary to observe that education does not mean the imparting and acquiring of information, but rather the cultivation of the faculties so that the best use can be made of them and of any information acquired. For instance, a man is not educated who has by heart his lectures and the contents of his text-books, but that man is who remembers little of the actual wording of his text-books, but is able to find anything required in them...

Jan 1, 1909

Drilling at Ipswich during the last twelve years by the Queensland Department of Mines has proved large quantities of reserves which have assured the security of the field for many years to come. This is perhaps the greatest contribution to the development of the field since its discovery in 1827.The drilling campaign commenced in 1950 and by the end of 1961 comprised 242 holes totalling 180,220 ft.Intersections of formations and seams, accompanied by detailed surface mapping, led to more precise knowledge of the geology of the field than was previously possible, and clarified many problems of correlation. Productive formations are part of the Middle Triassic Ipswich Coal Measures, a 4,300 ft sequence of fresh-water sediments with some interbedded volcanics. They are overlain by the Upper Triassic Bundamba Group and the Lower Tertiary Booval Group.Reserves disclosed by drilling amount to 171,487,000 tons, comprising 109,407,000 tons "measured" and 62,080,000 tons "indicated". The security of these reserves encouraged many collieries to instal modern efficient mining machinery and washing plants.The climax of recent development of the resources of the field will be the commissioning in 1966 of a £33 million 360 MW power station in the Swanbank district which will consume 14 million tons of coal during its 30 year life and will have a peak demand of some 20,000 tons per week.Drilling is continuing and is expected to prove additional reserves which will justify further development of the field.INTRODUCTIONUntil 1949 there had been no concerted effort to test systematically the resources of the whole Ipswich field. Fifty two known holes totalling 30,500 ft had been drilled, eight of them by the Department of Mines, but because of poor core recovery and inadequate records most of them were of little use in a comprehensive assessment.Development of the field was being retarded by uncertainty regarding reserves and by the general state of the coal mining industry. Numbers of comparatively small independent companies and owner groups were operating coal...

Jan 1, 1963

By A Seneviratne, Y Li, N Udugampola, X Ai, B Li

LoRa (Long Range) is a low-power, long-range wireless communication technology that has gained significant research interest for its potential use in multi-hop linear wireless sensor networks (LWSNs) for underground mines. These networks deploy LoRa-enabled sensor nodes in underground mines, together with LoRa repeaters placed along mine tunnels to relay sensor data to a LoRa gateway, which connects to a backend network for application-level processing. Since the packets generated by sensor nodes farthest from the gateway have to hop through many repeaters, their probability of successfully reaching the gateway is significantly lower due to the higher chance of packet collisions compared to sensor nodes closer to the gateway, resulting in a lack of network fairness for the sensor nodes. In this paper, we first present an algorithm to improve the fairness of a LoRa LWSN by grouping neighbouring nodes and adjusting the number of packet re-transmissions and transmission intervals for each group. Then, we demonstrate that the fairness of a simulated LoRa LWSN can be improved by approximately 500 per cent by applying our algorithm. We verify our algorithm with network simulations under different network traffic levels and grouping strategies, obtaining fairness improvements in each scenario. Our algorithm and results will pave the way towards developing highly fair LWSNs for underground mining applications.

Sep 1, 2024

By JOHN G. RAYNER

An examination was made of the filtration characteristics of a haematite slurry using a range of polyacrylamide based flocculants in solutions containing up to 3 per cent sodium chloride. The polymers used were "high" and "Iow" molecular weight and had from 0 to 40 per cent charged groups.Increasing charge density tends to reduce the dose required to achieve optimum performance measured by filtration rate and by cake moisture. In general increased salt addition tends to increase the dosage required to achieve these optima. Both these observations result from the change in polymer extension and accord well with the bridging theory of flocculation.The dose required for optimal cake moisture is up to three times greater than that required for optimal filtration rate. This effect is reasonably consistent for all polymers studied and appears to be non-linearly dependent on salt concentration, with the difference being small at 0 and 3 per cent but quite significant at 1 per cent.

Jan 1, 1987