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Rock bolting provides a supplement or alternative to conventional timber and steel supports. The tensile strength of the bolts lies within a range established by manufacturing quality control. Rock bolt testing determines the ability of the rock, anchor and individual bolt as an assembly to accept load. The.test is performed to the yield strength of the bolt or anchor and deflection is observed. The anchorage index, inches deflection per 1000 lb load increment, is a measure of anchorage quality. This allows comparison with anchorages under ideal conditions. It also permits comparative assessment of roof bolt anchors in a particular environment.

Jan 1, 1971

By W J. Shaw

Geometallurgical modelling is now a hot topic in deposit evaluation and in optimising mine performance; however, its history is long and varied. Historically metallurgical sampling has frequently suffered from a lack of data due to the cost of producing representative bulk samples. In the early 1990s geometallurgical modelling similarly suffered from a lack of data due to complex, time consuming and expensive sampling techniques. More recently, simple and relatively cheap tests for geometallurgical variables such as hardness, grindability, throughput, SAG power index, bond work index, crushing index, mineral recovery and concentrate grade have become widespread. The cheaper sampling has resulted in relatively large geometallurgical databases. However, most of the geometallurgical variables sampled are implicitly (and incorrectly) assumed to be additive when modelled by traditional geostatistical techniques, often leading to ill-informed and costly decisions. Geometallurgical variables are mostly non-additive so the current geostatistical challenge is to develop new approaches to dealing with this type of data. This paper briefly describes a historical case study of geometallurgical modelling of the George Fisher Pb-Zn mine completed in the mid 1990s, then outlines some of the current misconceptions of geometallurgical data and modelling techniques regularly applied to it, and finally discusses some recent developments in geometallurgical modelling, with examples from a number of current clients indicating the direction forward.

Jan 1, 2009

Underlain by and intruded into the sedimentary rocks of the Transvaal Supergroup the Bushveld Complex is the largest known layered intrusion in the world and contains one of the richest ore deposits on earth. It has been the world's major source of Platinum Group Metals (PGM) since the mid-1900s with Chromite and PGMs the two most economically important components of the Bushveld Complex. The lower group (LG), within the critical zone, consists of seven chromitite layers and it is within this sequence of chromitite layers, the most important target of the lower chromitite group is found, ie the LG6 chromitite unit. The LG6 chromitite unit consists of a chromitite duplex composed of the lower LG6 chromitite layer (Steelport seam), averaging 1 m thick, overlain by a 0.66 m waste parting and a thin 0.34 m thick LG6a chromitite layer (leader layer).Two mining methods are commonly applied in the Bushveld Complex to extract the LG6 chromitite layer package. One method consists of footwall development utilising rail bound equipment to gain access to the orebody and then extracts only the LG6 chromitite layer by means of hand held rock drills and scraper winches. The second method is the use of mechanised equipment to access the orebody on the plane of the ore utilising bord and pillar mining method, which extracts the full mineral resource, ie the LG6 and LG6a layers. Conventional narrow vein stoping is often selected due to the large conventional mining skills base found in South Africa, the perceived cost and dilution implications of utilising mechanised equipment, and the difficulties of using mechanised equipment at dips above 12¦. The driving factor for mechanised mining is the perceived ability to access the orebody quickly and inexpensively, and extract the entire mineral resource package (LG6 and LG6a) while limiting capital expenditure and improving safety.This paper investigates these two commonly applied approaches, highlighting the benefits and problems associated with the two approaches. Comparisons will be made of the two mining methods and recommendations given for the mining engineer to consider before selecting the appropriate mine design.

Dec 6, 2010

By M Denton, M Rheinlander, S Mundell, M Broadgate

The manufacturing industry reinvented its approach to the manufacturing process by managing and measuring it end-to-end. This improved returns on production assets, improved information quality and reduced delivery time, resulting in larger net profits through cost reduction and improved cash flow. Today this approach is standard in the manufacturing industry. Resource development has many requirements in common with the manufacturing production line. These include: control of the various steps, transparency of the state of the process to various levels of the organisation and the overall efficiency with which the process is executed. The authors argue that the introduction of manufacturing execution systems (MES) concepts and technologies to resource development processes will lead to similar improvements in control, transparency and efficiency and could improve profitability and enable staff to work more effectively and make better decisions.

Jan 1, 2009

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

By Ramsay WRH

The Mount Stavely Volcanic Complex compri- ses one of a number of northerly trending fault bounded greenstone occurrences in Western Vict- oria, of probable Cambrian or older age. The greenstone belt is coincident with several linear positive aeromagnetic anomalies, which outline the surface and subsurface extensions of these greenstones. Mapping at Mount Stavely has identified serpentinite, variolitic basalt, two-pyroxene and pyroxene-hornblende andesite, dacite, rhyodacite and their pyroclastic equiv- alents. Chemically and mineralogically the volcanics constitute a calc-alkaline assemblage. The mineral potential of the region has been enhanced following a discovery by Pennzoil of Australia Limited near Ararat, of sulphide min- eralisation containing approximately 1 million tonnes at 2.7 percent copper. The volcanic environment of the Mount Stavely Volcanic Complex is discussed in terms of similar environments found in Canada.

Jan 1, 1982

The problem of manufacturing from sulphuric 'acid and Christmas Igland "A" phosphate, superphosphate of acceptable physical condition and agronomic phosphate availability, is directly related- to the crystallisation of a reac- tion product, monocalcium phosphate monohydrate. Two solutions to the problem, vacuum drying the superphosphate and calcination of the ore before reaction with acid, are discussed.

Jan 1, 1971

By Morandini AF, Occella E, Clerici C, Mancini R

This contribution presents the first results of an experimental research aimed at finding an unified description of the first stages of a rock comminution process. With reference to the case of the jaw crushers and to the specific subject of the comminution law, the tests reviewed and analysed in this contribution have been carried out, at a laboratory scale, on five different materials (limestones, quartzite, serpentinite) at different reduction ratios and feed rates, and accurately recording both total power and idle running power. The analysis of the results has shown that: ò the grain size distribution of the products complies with a modified form of the Rosin-Rammler equation, already found to be well suited to representing the grain size distribution of blasted rock in previous works by the authors; ò observed trends of the consumed power at increasing reduction ratios is steeper than predicted by the classical Rittinger, Kick and Bond laws, Rittinger law representing however a closer approximation of the experimental results; and ò a more accurate description of the experimental results is provided by a modified form of the Rittinger law. Accuracy of the semi-empirical expression has been found to be usually better than ten per cent by comparing actual results with expected Results.

Jan 1, 1993

By N Voller, A Ishmurzin, G Hackl, M Wu, A Kharicha, M Chintinne, C M. G Rodrigues, A Ludwig

Slag fuming (SF) is a critical process for recycling zinc-containing slags, but the corrosive nature of molten slag poses challenges to the reactor durability. The freeze-lining (FL) technique offers a solution by forming a protective layer on the reactor wall. It requires intensive cooling using watercooled jackets, which can stabilise the FL while compromising the energy efficiency of the process. This study presents a computational fluid dynamic (CFD)-based model to optimise the SF process by considering FL formation and its impact on heat transfer and reactor wall temperature. A volumeof- fluid (VOF) model is coupled with a mixture continuum (MC) solidification model to capture the intricate multiphase flow dynamics within the SF furnace. Two FL types are considered: FL solidifying on the reactor wall in the slag bath region; and FL solidifying on the reactor wall in the freeboard region. The FL of the first type forms when the slag temperature drops below liquidus temperature. The FL of the second type only forms when a splash-induced slag droplet collides with the freeboard wall and solidifies. A series of splashing events are necessary to coat the freeboard wall. The simulation was run until a global energy balance was reached. This means that the heat losses from the water-cooled jacket, bottom wall, outlet and fuming balance the heat gains from the hot gas injected through the submerged plasma torches. The increase in FL thickness, due to its low thermal conductivity, reduces the heat losses through the reactor walls. The calculated FL thickness and heat fluxes were in good agreement with industrial data, validating the model’s credibility. The simulation results provided valuable insights into the fuming process, including slag bath temperature evolution, slag splashing dynamics, FL formation patterns, local heat fluxes through the reactor wall and overall energy balance. These findings can inform process optimisation strategies to enhance the energy efficiency and sustainability of SF operations. The authors have built a prior version of the model framework and applied it to simulate FL formation in an electric smelting furnace (ESF). The results from both the ESF and the current SF highlight the applicability of such model framework to a range of industrial processes involving FL formation. This model framework can ultimately contribute to more energy-efficient and sustainable industrial operations.

Aug 21, 2024

The Sto Tomas II orebody of Philex Mining Corporation is a porphyry copper deposit located at Padcal, Tuba, Benguet, Philippines. It was mined through open pit method for the first two years starting 1958 and subsequently through underground method using the Block Cave System. The slusher type of draw was employed at the upper levels of the orebody from mid-year of 1959 up to 1994 and then shifted to LHD as the ore became more competent at the lower levels. Application of rock mechanics played a vital role during the conceptualisation of the LHD method of draw, the first of its kind in the Philippines. Rock mechanics is a combined responsibility of the geology and the mine engineering staffs, with the geology providing the vital information to the mine engineering to include in the mine planning the following:the general geology of the orebody; the ground characterisation through rockmass classification; determination of the cavability of the ore column (this includes our experience on airblasts which occurred during the early stage of our last slusher blocks); undercutting sequence; fragmentation of the rockmass in the ore column; drawzone spacing; proper draw control procedure; lay-out of openings; and the design of ground supports based on the rockmass condition. For the proper interpretation of the rockmass that would cater to the diverse mining situations, Philex adopted the modified geomechanics rockmass classification (Mining Rockmass Rating, MRMR) as this system is recognised and used by most of the block cave mine worldwide. This paper aims to discuss and present the role of rock mechanics in the analysis and determination of geomechanical issues encountered in Philex mechanised block cave operation.

Jan 1, 2000

By A B. Christie

In Northland, Coromandel, Taupo and Canterbury, weathering and hydrothermal alteration of Cenozoic volcanic rocks has resulted in the formation of various types of clay deposits. Subtropical weathering of rhyolite in the Matauri Bay area (Matauri and Mahimahi deposits) in Northland has formed high quality halloysite deposits. The Matauri Bay halloysite is mined and processed to produce reputedly æthe world's whitest clayÆ that commands a high price in niche ceramic markets. In the Coromandel, some argillic alteration zones contain kaolinite clays (at Hahei) and advanced argillic alteration zones contain kaolinite-gibbsite-pyrophyllite assemblages (at Pumpkin Hill and Lookout Rocks). In addition to known halloysite and kaolinite clay deposits, there is also economic potential for smectite clays produced by hydrothermal alteration of volcanic rocks. Bentonite (mainly ferriferous-beidellite) is mined from weathered basaltic ash in Miocene lake beds at Coalgate in Canterbury.   We have compiled interim mineral deposit profiles for bentonite in basaltic ash, halloysite in rhyolite, kaolinite in altered rhyolitic rocks, kaolinite-gibbsite-pyrophyllite clays in advanced argillic alteration zones and for smectite clays in argillic alteration zones. These deposit profiles include geological and mineralogical attributes, which are linked to the underlying volcanic, hydrothermal and weathering processes that have produced the clay minerals from their source volcanic rocks. Further work on refining the deposit profiles includes characterising the composition of selected deposits to determine spatial trends in mineralogy and geochemistry.

Jan 1, 2007

With constantly rising energy costs it is ever more important that we look at ways of im- proving comminution efficiency both in terms of power consumed as well as capital costs required for purchasing and installing equipment. I intend to show that commonly used appli- cation criteria, which is presently accepted for designing crushing and screening plants, need drastic revision if it is to be used to accura- tely design, predict and refine performance in new and existing facilities. Unless we can calculate performance accurately, we cannot minimise capital investment and maximize Profitability.

Jan 1, 1978

By Bevan JE

The US Bureau of Mines is conducting research to improve the health and safety for underground coal miners, and the efficiency of the mining systems that are used. In 1986, the Bureau began a major research effort on the technology for computer-assisted mining systems for underground coal mines. The initial target was technology for continuous mining machines that would allow them to extract coal by computer-assisted operation. Technology areas being investigated include guidance systems, machine condition systems, computer systems, machine control, human-machine interfaces and planning. In each of these areas, individual system development has progressed to where underground testing of these systems will begin in 1991.In addition to coal extraction, the Bureau has also begun research for the development of technology for computer-assisted roof bolting. The Bureau is developing technology for a "smart" roof bolter that would be able to sense and analyze strata conditions to determine the requirements to provide a competent roof. The system would determine the location of the hole, drill the hole to length, and select and install the appropriate bolt.

Jan 1, 1991

By B S. S Rao, S Chandra

IndiaÆs iron ore mining industry is growing rapidly in order to augment the capacity to meet the unprecedented demand for the iron ore. Traditionally, much of Indian iron ore production came from exploitation of high-grade haematite ores, with the exception of Kudremukh which beneficiates lean grade Banded Magnetite Quartz ore. Now with the changed scenario of demand and supply, keeping long term sustainability in mind, it is imperative to develop suitable processing technology for exploitation of banded haematite quartz (BHQ) ore available abundantly and not utilised so far. In this direction detailed characterisation and beneficiation studies were conducted with BHQ iron ore from the Bellary-Hospet region of India, assaying 36.5 per cent Fe. The mineralogical studies with the image analyser system revealed the presence of maghemite and haematite as iron-bearing minerals. The gangue mineral associations were siliceous, ferro-magnesian and carbonate minerals. Higher degrees of liberation were observed in the size range of 75 - 212 microns. Liberation grind tests were performed by grinding the ore to different top sizes in a closed circuit laboratory ball mill with the ground samples subjected to Davis tube tests. The yield, grade and recovery were used as parameters to plan a two-stage wet drum magnetic separation based on grinding the primary magnetic concentrate. After subjecting the final magnetic concentrate to flotation to remove residual silica a concentrate assaying more than 68 per cent was obtained. The non-magnetic product from the primary magnetic separation was deslimed, ground, blended with secondary magnetic tails and was subjected to a two pass wet high intensity magnetic separation (WHIMS). The WHIMS concentrate was further subjected to two-stage flotation to remove residual silica to obtain concentrates assaying 64 - 66 per cent Fe. The final combined concentrate from wet drum magnet and WHIMS after flotation could yield a blast furnace (BF) grade pellet feed concentrate assaying more than 65 per cent Fe with a yield about 39 per cent and iron recovery about 70 per cent. A direct reduction (DR) grade pellet feed concentrate assaying 67 per cent Fe with a yield of about 28 - 31 per cent and iron recovery about 53 - 57 per cent could also be produced. Based on the test work, a process flow sheet was developed to beneficiate the BHQ ore for production of BF/DR grade pellet feed concentrate. In this paper methodology adopted for selection of individual process, various diagnostic tests performed to rule out other beneficiation processes and the final process flow sheet development is presented and discussed in detail.

Jan 1, 2007

By Ketteridge IB, Mulcahy DE, Quast KB

The long term energy demands in South Australia are such that there is a distinct possibility that one of the lignite deposits in the State will be exploited to feed a pulver- ised-fuel power station. Bowmans lignite deposit is the largest lignite deposit in South Australia and is considered to be a contender. The deposit is ideally situated (100 km north of Adelaide) but the quality of the lignite is poor (see Table 1). TABLE 1

Jan 1, 1984

By Phillips H. R

The action of free rolling disc cutters is well understood, relationships between disc geometry and performance having been established both in the laboratory and under field conditions. However, under severe operational conditions a malfunction of the disc bearing assembly is likely to produce a definite change of cutting action. Collapsed or siezed bearings can even prevent the disc from rolling and thereby create what is equivalent to a drag pick. This paper describes a programme of laboratory experiments using deliberately stalled discs. Their performance under such conditions is contrasted with that for a free rolling disc and also with a drag pick having a ridged front developing into a negative radiused back clearance angle. In conclusion an assessment is made of the influence stalled discs can have on the torque and thrust requirements for a tunnel boring machine.

Jan 1, 1981

By Brinkmann J. R

The relative effects of the two basic mechanisms contributing to rock breakage during blasting, shock and gas penetration, are neither well understood nor well characterized, and need further clarification. Blasthole liner (BHL) tests separate the two effects, and by enabling direct measurement of borehole expansion give insight into the shock/gas energy partitioning in rock confinement. The hydrodynamic code DYNA2D is used to simulate the shock effect of the detonation of emulsion in a stainless steel lined hole, and the predicted expansion is compared with experiment. Workers in the past have neglected near-blasthole phenomena and have calibrated models based on stress measurements remote from the blasthole. Extrapolation back to the blasthole has inherent limitations, and indeed, one of the deficiencies of these models is that they have not been able to predict correct borehole expansions, as observed in BHL experiments. DYNA2D has been enhanced by the ICI group with a detonation model which resolves the explosive reaction zone. As a preliminary step towards the ultimate goal of devising a practical damage model, simulations are used to predict the maximum expansion that would take place if the rock were to remain undamaged. Various material parameters are investigated and it is shown that calculated liner expansions are appreciably lower than measured values for high rock yield strengths, while greater than values for low yield strengths.

Jan 1, 1990

By R Lurf, C Weber

In the frame of this paper a holistic dynamic process model approach is presented in order to introduce operational and technical excellence in drilling and blasting. Both on a macro and micro level the single process parts of drilling and blasting are outlined and their interaction is explained. The use of this approach for closing the gap between process planning and process implementation is explained and an example of the value generated is given.

Jan 1, 2007

Although this is a symposium on "The Occurrence, Preparation and Use of Australian Black Coal", I do not think that, in these days, any of the main energy resources can be considered only in terms of country of origin or only by itself in isolation from other energy resources. Accordingly, I propose to comment on solid fuels generally in the world energy scene, and make some brief references to Australian solid fuels, and to some other matters in the latter part of this paper. In this address I am drawing heavily on the 1974 survey of energy resources published just recently by the World Energy Conference. I do this for a number of reasons. Firstly, the survey is the latest and most comprehensive publication of its kind; secondly, it is the result of several years' work by a panel of eminent people, from all the energy industries and from some 16 widely spread countries; thirdly, substantial assistance was given by the U.S. Atomic Energy Commission in its compilation; and, finally, to let all know of the existence of the book, as I believe it to be a source document for all those interested in world energy resources. The United Nations "J" series of statistical papers provide important information on the annual production and consumption of and trade in the various forms of energy. In their respective areas, these two publications are primary information sources. Our present sources of energy throughout the world are fossil fuel deposits (coal, oil, gas), nuclear materials, water, geothermal, solar and tidal - but we are at present heavily dependent upon the natural stores of non-renewable fossil energy resources. Fig. 1 shows the changing use of energy resources in the present century. A comparison between 1900 and 1973 shows clearly the shift which has taken place.

Jan 1, 1975

King Island is situated at the western approach of Bass Strait and approximately mid way between Victoria and Tasmania. The scheelite orebodies lie within the south east of the island. Ore bearing horizons from 10 m to 40 m thick occur in south and east dipping stratiform deposits. The orebodies occur in skarn formed by contact metasomatic replacement of carbonate rocks by granite intrusives. The scheelite is deposited as fine disseminated grains in and along the margins of andradite garnets in the skarn. King Island Scheelite operates two under- ground mines from which 350 000 tonnes per year are obtained. The Dolphin mine produces almost two-thirds of the total. See Figure 1. The Dolphin orebody lies beneath the sea and an area of reclamation. The orebody is inter- sected by zones of major dislocation. A chequerboard post pillar cut and fill stoping system has been chosen to provide the necessary support to the hanging wall. Because the stability of the pillars is critical to the economic welfare of the mine, considerable attention is given to the reduction of overbreak.

Jan 1, 1977