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By P Cepuritis, G Chitombo a, I Brunton

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

Jan 1, 1999

Information from bores in the LatTobe Valley has been accumulating for over fifty years, and the manual extraction of details has become a limiting factor in their use.Punched card equipment, installed by the State Electricity Commission for accounting purposes, was known to be available for reasonable periods, and it was suggested that this could help in the extraction of data from the voluminous records.Investigation showed that they could be substantially duplicated on cards, with consequent gains on many operations; the cards being regarded as an auxiliary to the existing records.BRIEF DESCRIPTION OF RECORDSAs a bore is drilled a continuous record of the strata is kept, together with notes on the presence of water or any unusual features which the driller may observe.When coal is struck, samples of each ten feet are usually sent for analysis.The location and surface level of each bore is fixed by surveyors, and details of dates and methods of drilling are also kept.Bores are allocated numbers, prefixed by the name of the parish within which they are drilled. Numbers are allocated in conjunction with the Department of Mines, to avoid duplication.Records of strata and analyses are kept in folders, with 100 bore numbers per folder.Standard plans are drawn, showing the locations, bore numbers and surface levels. For each bore they also show the depth and thickness of coal struck, and the total depth drilled.Cross sections are then drawn, connecting the various coal seams, which have been identified by the geologist.

Jan 1, 1960

By M Roberts

The aim of this paper is to evaluate the technical feasibility of application of the electric monorail as a haulage system in hard-rock underground mining in Australia, in comparison to conventional truck haulage systems. The elements of the system being investigated include mine design and layout, installation, loading and unloading subsystems, tramming speeds, cost and productivity, automation, ground support, safety and environmental factors. Electric monorail systems are potentially more cost-effective due to a range of factors: only the one system may be needed for the transportation of workers, material and rock; and excavations for monorail haulage can be smaller and mined at much steeper gradients than for truck haulage. The smaller excavation size also reduces the need for costly ground support and û in another important measure for the health and safety of mine workers, and for energy savings û it reduces ventilation requirements. Electric monorail haulage technology is being applied in hard rock mines in South Africa and considerable benefits have been realised by the industry in that country. In Australia, mine designs for metal mines generally remain based on truck haulage and/or shaft hoisting systems. There is a tendency to apply these haulage systems to every orebody. For the industry to achieve sustained growth against a backdrop of volatile diesel prices and environmental concerns, new generation underground haulage systems are required. The monorail haulage system offers opportunities in improving materials handling efficiencies in underground mining operations. This paper examines the application of monorail haulage in metalliferous underground mining, presents comparative data with track and trackless haulage systems and develops concepts for system application in combination with conveyor belt haulage and narrow vein mining situations.

Jan 1, 2005

By Menne DM

The carbon-in-pulp (CIp)process has become well accepted and firmly established in the gold industry of South Africa and, at this stage, six large CIP plants are treating close to I million metric tons of material per month. Many small operators are also using CIP and additional large plants are either nearing completion, are on the drawing boards,. or are being considered. The programme of testwork that preceded the acceptance of the CIP process in South Africa was conducted over some eight years and has been previously described'-7. With the start-up of the President Brand CIP plant on 'calcine' in July 1980 and that of the Western Areas CIP plant on repulped filter residues in September 1980, the emphasis on the CIP process switched from pilot plants to these large plants - and has largely remained there. As it has started up, each new CIP plant benefited from the experience gained and the developments made, on earlier plants but, since so few plants have so far been established in South Africa, each new plant and each new design has revealed a further set of conditions to be met and problems to be overcome. However, in the highly collaborative atmosphere of the South African gold-mining industry, the results and observations from the operation of these first plants were shared by all mining groups. This paper will attempt to describe typical developments on, and results obtained from, these new large plants, and will incorporate significant results from the earlier laboratory and pilot-plant investigations.,

Jan 1, 1982

Placer Dome Asia Pacific operates eight mines in the region and has two closed operations that are either under rehabilitation or at the latter stage of care, monitoring and maintenance. All operating mines are scheduled to close within the next ten years based on current proven reserves. Mine closure planning and associated risk assessments are integrated into both strategic planning and day-to-day operations within the Placer Dome group. Mine closure is all about predicting the potential risks and Placer DomeÆs knowledge has improved following the planned closure at Kidston Gold mine in North Queensland. Planning for closure commenced in earnest in 1994, and focused on identifying the issues and associated potential risk to the environment, and ensuring that the most suitable control measures were implemented leading up to and following closure in July 2001. At all times during the process of planning, implementation, safety contractor management and post closure, the identification of risk and potential threats to the business have been identified and managed. Post closure risk assessment of rehabilitation strategies potential to fail has been completed in conjunction with URS and opportunities to manage these potential failures in perpetuity will be discussed along with lease surrender. Misima Mines is currently processing low-grade ore and plans to close in 2004. Planning for closure has been ongoing for several years with a focus on the social aspects and the impact of the mine closing on a remote island community. Misima Mines has assessed the risk profiles using a community closure focus group, to identify both the biophysical and social aspects for closure.

Jan 1, 2003

ALTHOUGH discovered as long ago as 1817, by Strohmeyer, the use of cadmium did not become in anyway general for nearly a century. Its properties, although well known, did not recommend it to users of metals generally, and it was, on the whole, regarded more in the light of a nuisance to zinc producers than anything else. Its real value was not appreciated until both the United States of America and Germany, who are entirely dependent on outside sources for their supplies of tin, were faced with the unpleasant fact that their tin stocks were being rapidly depleted, with practically no prospect of having them replenished. This resulted in serious efforts being made in the UnIted States of America to conserve what tin was available, and, as a consequence, several metals were tried in the hope that they would prove satisfactory substitutes for tin. Among these was cadmium, and it was found that cadmium could replace tin in a manner sufficiently satisfactory to permit of its use in many directions where tin had been used before.It is on this ability of cadmium to replace tin that its use became in any way general at first; but since then new avenues of development have been opened up in which its physical and chemical properties are proving their value. It is highly probable that its use will extend very considerably as time goes on. OCCURRENCE OF CADMIUM.There are several cadmium minerals known, but none of them occur in profitable quantities as ores. The cadmium of commerce is derived almost entirely from zinc minerals and ores in which it is almost invariably present in proportions which are usually very small. Cadmium behaves metallurgically almost the same as zinc, and hence constitutes a fraction of 1% of almost all spelter.

Jan 1, 1923

Mine planning is difficult. Even for small operations, it involves reasoning with complex variables and the practical difficulties of mining. It is also about predicting and planning the future in an unpredictable physical and economic environment. Yet we rely on a handful of individuals and their spreadsheets to tell us how to do it û planning the business and activities of mining to hopefully produce results that will please stakeholders. Does it work? Not as well as it could. Planning affects everyone in the organisation. Company executives are demanding more reliability and stability in cost and revenue forecasts from their operations. Management want to explore ways of being more cost effective. Miners and contractors want more useful plans and realistic targets. And the planners have to describe the method that will translate business objectives into implementable plans. Even with the use of computer technology a lot of effort is expended to produce plans that are largely qualified by the level of knowledge and experience of individuals. Better use of information and the application of Intelligent Technologies can improve the quality and reliability of mine plans and schedules. By capturing the knowledge within the organisation and speeding up the planning process, Intelligent Technologies allow more options to be considered more rigorously. But it is not just about technology. It is about how technology is implemented and embodied in the way the business is managed for performance. When this happens, the real benefits of better planning start to flow.

Jan 1, 2003

By B L. Dickson, J H. Hodgkinson

The self-organising map (SOM) is an exploratory data mining technique that is both non-traditional and underutilised. Methodologies based on SOM tend to be data-driven and unsupervised, which makes them ideal to assist in the integrated analysis and interpretation of complex and disparate æmineral explorationÆ data sets. While traditional statistical multivariate approaches have difficulty with relationships that are non-linear and data distributions that are not normal, SOM-based data mining procedures are useful in these circumstances. In a SOM analysis each sample is treated as a vector in a data space defined by the variables; and measures of vector similarity, such as the dot-product or Euclidean distance, are used to order or segment a data set into naturally occurring populations. These groupings are positioned as nodes, or groups of nodes, on a 2D rectilinear representation of the multi-dimensional ædata spaceÆ, which is the æself organized mapÆ. While it is common not to include a sampleÆs locational information in the actual SOM analysis, such information can be used to display the spatial location of samples coded by their SOM node or cluster. If one finds there are coherent spatial patterns belonging to samples from particular nodes, or groups of nodes, then there is strong evidence that the technique is determining patterns and relationships within the data that have natural significance. Variations of the SOM technique may be used to perform broad categories of operations, including: 1. outlier identification û for samples belonging to various nodes or grouping of nodes; 2. function fitting, prediction, estimation or imputation û for calibrating relationships between variables and determining replacement values for missing, null or censored values; 3. clustering, pattern recognition or noise reduction û for determining the natural patterns within a data set; and 4. classification û for classifying samples into the clusters determined in three. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Australia, with its fast-growing economy and high standard of a~ living, has a high and rapidly increasing per capita consumption of energyIn total terms, Australia's energy requirements are doubling every 15 years, and among mature Western economies Australia ranks behind only Italy-and Japan in the rate of increase of energy consumption.The use of energy is often accepted as a yardstick of development and on this basis Australia might well congratulate itself on its high energy consumption. However, it is less well recognised that the resources absorbed in the production of energy represent a real cost to the* community, and that just as we strive for industrial efficiency or farm productivity we should strive for economy in the use of energy fuels.Australians spend annually an estimated ú500 million.on all forms of energy, a sum which represents about seven per cent of the Gross National Product. In all, energy production and distribution absorb the employment of more than 100,000 persons. In addition, the annual capital investment by.the oil industry amounts to some E55 millions, by the coal industry about ú12 millions, and by electrical and gas authorities some E108 millions, in total representing more than ten per cent of annual investment in other than private motor cars and housing,

Jan 1, 1962

In November 1992, the Internal Revenue Commission (IRC) was formed from the rperggr of the Papua New Guinea Taxation Of- fice (PNGTO) and the Bureau of Customs, and now has the re- sponsibility for the administration of direct and indirect taxes on a national basis in Papua New Guinea (PNG). Since that date we have undertaken many initiatives to make the new organisation more efficient and responsive to clients' needs. Income Tax The mining industry is catered for, in respect of income tax, un- der a separate taxation regime within the Income Tax Act (ITA), Division 10, as well as some general provisions within that Act as may be applicable. Division 10 is itself broken up into subdi- visions to cover the different types of mining leases, namely Spe- cial Mining Leases (SMLs) and Mining Leases (MLs), and peri- ods of time during which those sub-divisions apply. Ring Fencing Income tax assessed on the mining industry, with the exception of Mining Leases (these will be explained later), has a project basis of assessment, that is, each project is assessed separately as if the taxable income of the taxpayer from operations attributable to the project was the only assessable income derived by that taxpayer. This is often referred to as "ring fencing". This is an important point to consider because losses from unsuccessful projects cannot be set off against income from those that are suc- cessful, except in very limited specific circumstances, such as where an unsuccessful exploration licence is cancelled or surren- dered. The project basis of assessment applies to both resident and non-resident companies. A relaxation in the 'ring fence' provisions was applied from 1st January 1995, where ten percent of exploration expenditure, in- curred in areas outside of Special Mining Leases and Petroleum Development Licences in a particular year of income, can be claimed as an outright deduction which is limited to ten percent of the tax otherwise payable in that year. This was introduced to encourage exploration in PNG.

Jan 1, 1997

Segregation of granular material is a very common phenomenon. Realised in a forced manner it is a basis of all separation processes in mineral processing, mainly classification and beneficiation. Spontaneous segregation, occurring under dynamic conditions and making possible mutual translocations of grains, is however an undesired phenomenon as a rule. It decreases the degree of blending of the material which in many cases is an important technological feature of the material. It should be noted that the segregation can be treated as the reverse phenomenon to blending. The importance and frequency of spontaneous segregation has caused many rules and technical solutions to be developed aimed at decreasing the possibility of the spontaneous segregation. However, not enough attention has been focused on an quantitative description of the phenomenon of segregation, either to ways of quantitatively evaluating segregation effects or to explanation of the influence of conditions under which the grained material exists on the occurrence of segregation and its degree. The paper presents the following topics: 1. new numerical indicator for evaluation of the segregation degree (and blending) of material contained in an arbitrary determined region is proposed; it is determined relative to the maximum possible degree of segregation of the given material when taking into account its individual properties; values of the indicator can be calculated effectively for an arbitrary material, also for ulticomponent material. 2. there is proposed a way of evaluating the state of segregation (or blending) of material in an arbitrary part of the region mentioned above, based on investigation of the gradient of distribution of the material features; algorithms of analytical procedures and calculations are presented for typical cases met in mineral processing; 3. results of initial experimental studies, both laboratory and industrial, concerning the effect of the chosen factors occurring in transport and storage of the material on its degree of segregation are presented; and 4. conclusions referring to the fundamental and practical significance of the results are also presented.

Jan 1, 1993

By Costello MC

An alternative process for desorbing and recovering metals from activated carbon has been developed, and is the subject of several patent applications by Micron Research (W.A.) The system uses the principle of conditioning the carbon in a strong alkaline cyanide solution followed by distillation desorption in a fractionating column, using the carbon as the column packing and methanol as the desorbing agent. The system offers the following advantages : (a) The processes of desorption, methanol recovery and reactivation are all carried out in a single column with the carbon itself acting as the column packing. No other desorption plant items or fractional distillation equipment are required. (b) The metal values are concentrated into the water content of the carbon and no other water is used except as condenser coolant. This produces very high grade gold silver solutions which give high current efficiencies in the electrowinning step. These high gold concentrations allow almost complete separation of gold and silver from copper in the electrolytic cell. (c) The process is completed to a tailing assay of less than 200g Au/tonne carbon in 15 - 20 hours allowing turn around of carbon batches on a daily Basis.

Jan 1, 1982

By K Dudley, D Readett

The design of entrainment control processes in copper SX plants has been studied by use of models based on achievable plant performance. A number of alternatives have been assessed for their suitability in minimising the transfer of deleterious species from PLS into the electrolyte. The position of the wash (scrub) stage in the circuit, either before or after the loaded organic tank, has been the subject of considerable debate. The modelling shows that at ænormalÆ entrainment levels, the performance of the circuits are very similar. However at high entrainment levels the selection of the wash after the loaded organic storage has significantly lower transfer of contaminants. When considering the inclusion of a loaded organic coalescer the results of the modelling again show that the best circuit has the loaded organic storage/coalescer before the wash stage. The overall control of EW contaminants includes both a wash stage and an EW bleed flow. The total water use for these two flows is shown to go through an absolute minimum. The minimum flow rate is not greatly dependant on the total entrainment from the SX settlers. This can be a useful operating strategy if the quantity of high quality water for make up is limited by the capacity of the water treatment plant (eg RO). However the minimum cost option is to maximise the flow of water to the wash stage and minimise the EW bleed stream. The main driver for this is the cost of the cobalt sulphate contained in the electrolyte. Some results from the latest circuit modifications at the Nifty and Girilambone Copper Projects are presented to confirm the benefits of using both coalescing systems and a wash stage. The EW bleed has been reduced to a level that is less than the loss internally in the SX stage to stage entrainment. There has been an occasional need to add chloride to the EW to maintain sufficient concentration to act as a growth modifier.

Jan 1, 2002

THE object of this note is to set forth some particulars of the effect of light on cinnabar occurring in a deposit of this mineral at Puhipubi, in the North Auckland peninsula of New Zealand. This deposit is contained within a gently-inclined sheet of siliceous sinter forminga hillock called Mount Mitchell, and is particularly notable in that it is an instance of the simultaneous deposition of cinnabar and silica on a large scale. The mercury-bearing material varies in character from semi-porous sinter to dense translucent cbalcedony, of which the former is stained to various shades of pink, the latter to brilliant reds and vermilion. On exposure to daylight-and particularly to sunlight - these colours change to corresponding shades of translucent bluish-grey. As a direct result of this change the Mount Mitchell deposit remained unknown until some ten years ago, for, while prospectors early discovered cinnabar in the adjacent city and in a neighbouring stream bed, none of them recognized this mineral in the bluish chalcedony strewing portions of the surface of the Mount. The writer has carried out a series of experiments designed to indicate the cause and nature of this change, and to form a basis for the elaboration of more delicate experiments which would yield positive information. Circumstances, however, have so far combined to prevent the continuation of the research, and, as there seems little prospect of the writer being able to do more work on the subject, it seems well to publish the data so far obtained. Prior to describing this colour change, the writer would point out the desirability of restricting the meaning of the term cinnabar to the naturally occurring red sulphide of mercury; this would eliminate the ambiguities which arise from its indiscriminate application, in chemical literature, to both natural and artificial sulphides. Further the term cinnabarite having long since fallen into disuse, there appears to be no good reason for retaining the companionterm "metacinnabarite" when reduction to "metacinnabar" would preserve the meaning in a less clumsy word.

Jan 1, 1923

THERE is available a considerable amount of literature concerning the practice, and, to a smaller extent, the theory of ventilation as it applies to coal mines. Publications considering the subject of ventilation of metal mines from a practical viewpoint are much less numerous, whilst the treatment of the theoretical aspect of the question (except in so far as is common to coal mining) appears to have been almost neglected. This may be due to one of two causes (a) That in many metal mines (especially those which have not attained a great depth), on account of the greater number of connections with the surface, as compared with coal mines, natural ventilation has sufficed.(b) That in metal mines where the foregoing is not the case the solution of the ventilation problem from theoretical considerations has been regarded as involving so many complications that any attempt at the determination of a set of concrete ventilation figures applying to and throughout the mine would be futile. Whilst it is freely admitted that the difficulties inherent in the application of theory to the ventilation of metal mines are numerous, it must also be admitted that few attempts have been made to overcome them. The ultimate aim, of course, would be the collection of sufficient data to enable the probable behaviour of the air-currents throughout the whole of the workings of any mine to be accurately predicted under any particular set of circumstances. Failing the attainment of this goal of perfection, it would at least appear that much valuable information might be obtained. In ventilation, as in...

Jan 1, 1921

By A. W. CAMERON

Over a 4 hr period of steady plant operation samples were taken at regular intervals from points within the grinding and flotation circuits. Size fractions of each composite sample were analysed for lead and zinc values and a comparison made of the behaviour of the lead, zinc, and gangue minerals, size by size throughout the whole circuit.Analysis of the breakage behaviour using dynamic mathematical models gave the rates of breakage of each size fraction of each main component. Simulated grinding experiments showed that the main grinding circuit had some reserve capacity.In the lead flotation circuit all lead values between 150 mesh (Tyler) and 5 microns had excellent flotation characteristics, and a major proportion had a high rate of flotation which was practically the same for all sizes. Increase in overall lead recovery would require improvement of the flotation behaviour of ultra-fine lead minerals. These were slow floating and were responsible for approximately half the lead losses in the final zinc concentrate and one-third of the lead losses in the final tails.All sizes of zinc values between 100 mesh and 7 microns floated well and the performance of the zinc flotation circuit was mainly limited by the relatively poor flotation of the very fine zinc values. Approximately 60 per cent of the zinc lost to the final tails lay within the minus 7 micron fraction.The overall flotation conditions were conducive to very good selective flotation of the major proportion of the values and limitations in metallurgical performance were mainly due to the properties of the ultra-fines.

Jan 1, 1971

By D Pepper

Despite the limited literature regarding the pressure filtration of mine tailings (compared to the large number of papers published each year on paste thickening of tailings) the number of mines dry stacking filtered tailings is approximately equal to the number of mines storing tailings in paste form. Main drivers for filtering tailings are: water recovery, future rehabilitation costs for tailings storage area and permitting requirements. In arid climates, the cost and scarcity of water justify the capital and operating costs associated with pressure filters. Further justification for filtered tailings is the potential for progressive reclamation of the dry stack, which can proceed earlier and faster than the reclamation of a tailings dam.Filtered tailings must be transported to the storage area by trucks or conveyors. For dry stacking, 70 - 80 per cent solids content (by mass) is typically acceptable, however the primary goal is to provide a filter cake that is consolidated and dry enough to prevent bridging and build-up on the materials handling equipment. It has been observed that high average solids contents (~70 per cent) can be achieved while the centre of the filter cakes is still wet and sticky, presenting challenges for the transportation of the solids. Appropriate controls must be in place to ensure consistently easy to handle solids are discharged from the filter.FLSmidth has installed two fine coal tailings dewatering systems in the United States. One of these systems incorporates a Deep Cone Thickener« upstream of the filter press to minimise the amount of water that must be filtered, while the other tailings filter press is fed by a high rate thickener. The operation and performance of these filters is discussed and compared to the lab testing used to size the full-scale equipment.CITATION:Pepper, D, 2012. Operation of filter presses for tailings dewatering, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 241-246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

This is the time of year tor the presidential address, and with the present incumbent engaged in the coal mining industry, it will therefore come as no surprise to you that the theme of my address this evening is concerned with coal.There are other reasons for this apart from my contact with the coal industry. At present, coal is supplying considerable overseas revenue at a time when the remainder of the mining market is in a somewhat depressed state. That times will change goes without saying, if history is to be believed.However, so far so good for coal. My first reaction when The Institute indicated its wish that I be president for 1976 was to become deeply conscious of the honour bestowed on me.On consideration, I realized that very few past presidents have been intimately connected with the coal mining industry to the extent of indulging in it for lengthy periods as a full time occupation or, conversely, a part time interest for a long time. It also appears that not one had started their career in the industry. In my case, 'also, there were 8 very interesting years ,as a gold miner and metallurgist before commencing in coal.It therefore seemed appropriate to endeavour to discover ,why this should be so, as coal mining is now a very important part of a very important industry. What were the reasons why the industry took so long to emerge when there were ample reserves of easily accessible coal?Frankie and Johnnie in their bar room epic of the depression years concluded, and I paraphrase, that "their story held no moral, their story told no tale". If my story has such a message, it could perhapsbe construed as reinforcing the oft-repeated dictums, true or false, that "history repeats itself" or "man never learns".Coal mining is by far our oldest major Australian industry except for agriculture. Its history is almost as old as that of settlement:For various reasons, there has been a glamour associated with metal mining ventures which prob...

Jan 1, 1976

Three transient phenomena have been observed and experienced in the operation of large solvent extraction mixer-settlers. These relate to the ability of the settler to discharge streams with low entrainments arising from different phase separation æproblemsÆ. The operation of large-scale laboratory and commercial solvent extraction settlers has been shown by a number of workers to be a dynamic process, especially at the feed end. Circulating flow patterns are common in all three organic, aqueous and emulsion phases. The circulating patterns in deep dispersion bands in long settlers are believed to form roll fronts that can travel down the settler length within the bounds of the dispersion band. Various physical models are proposed to illustrate the formation and movement of roll fronts within the dispersion band. Another transient phenomenon has been observed in commercial settlers operating without any dispersion band. Entrainment of the continuous phase in the advancing dispersed phase is at high and erratic levels. This supports the conventional separation model, which recommends the presence of a significant depth of dispersion band to æfilterÆ the secondary haze from the bulk separated phases. The third transient is the position and shape of the dispersion band within the settler. Large commercial settlers have been shown to exhibit high variability in both these aspects of the dispersion band. The elimination of all three transient phenomena in commercial settlers has been shown to be effective with an in-settler media of coarse size and moderate specific surface area. The effect of the media is two-fold: it dissipates both the circulating flows and the forward velocity of any roll fronts, and creates a stable deep dispersion band at the feed end that serves to trap secondary haze from the primary coalescence process. It is effective in treating both types of transients involving non-existent or excessive dispersion band depths. The media serves to enhance coalescence by providing a static surface of intermediate surface tension on which droplets can collapse. The random nature of the media also provides multiple stream splitting and re-combination, that presents further drop to drop and drop to media impingement, which in turn promotes coalescence.

Jan 1, 2000

The key elements required to maintain final wall integrity and hence slope reliability are discussed. Failure modes and mechanisms in highly structured rock slopes are then reviewed. The impact of blast disturbance on rock masses in general is discussed and the relationships between the slope failure mode and blast disturbance is then explored. The question of how designers can incorporate such impacts into the slope design process is then addressed. This necessarily involves rock mass strength consideration and two case studies are used to demonstrate a recent dilemma in this regard. Some progress regarding this dilemma has also been reported for the second case study. The major conclusions are that: Slope reliability can be severely compromised if the slopes are damaged by blasting and this impact is not often incorporated into the slope design process. The location and extent of the blast damage will impact some slope failure geometries and failure mechanisms more than others. The concept of failure mechanism specific vulnerability needs to be further developed. The evidence indicates that this aspect is even more extreme for weak ground conditions. The quantification of the reduction in rock mass strength due to blast damage is not well understood and limitations exist with some recent guidelines. The use of the Hoek-Brown criterion for slopes in blocky rock masses requires considerable judgement. Further applied developments in this regard would be very beneficial to the industry. Some promising methods to incorporate blast damage estimates into the slope design process are emerging. It is good business to minimise final wall blast damage otherwise a whole range of issues relating to reduced slope reliability emerge.

Jan 1, 1999