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A small-charge rock excavation method based upon the Penetrating Cone Fracture (PCF) technique has been demonstrated to be capable of excavating the hardest of rocks. The PCF technique involves drilling shallow holes in the rock which are then pressurised at the bottom by a propellant charge device. A controlled fracture is initiated at the hole bottom comer and propagates in such a manner as to excavate the rock at an energy efficiency three to five times better than explosives. Due to the low flyrock velocities and airblast pressures realised with PCF breakage, the method may be used in close proximity to equipment and personnel and is thus ideally suited for integration into continuous hard rock excavation systems. Over the past 18 months full-scale testing of the PCF method has been carried out in mines in the US and Australia. This testing has utilised a 76 mm diameter gas injector for hole pressurisation and employed propellant charges ranging from 80 to 320 gm. In addition to extensive data on rock excavation performance, data on ground motion, dust, carbon monoxide and air blast have been obtained. These data indicate that none of the parameters associated with PCF breakage are detrimental to the development of PCF-based, continuous-excavation machines. Machines employing the PCF method may range from simple single-boom machines for secondary breakage and small precision-blasting jobs to integrated systems with several booms, continuous mucking capabilities and ground-support equipment for drifting and tunnelling.

Jan 1, 1993

With mining development on hold and other underground works in a slowdown, the development of nuclear wa te repositories takes centre tage on the American rock engineering scene. Three repositorie for commercial spent fuel-in salt, tuff, and basalt-are in the phase of site characterisation and conceptual design, and one pilot project for defense high-level wa te in salt is under construction. A repository design for crystal line rock has recently been postponed.Because of strict quality assurance requirements throughout design and construction, and because of the need to predict and ascertain in advance the satisfactory performance of the underground openings, much intellectual energy has been expended to analyse underground openings in the unusual circumstances of the repository environment. In the long term, these efforts will lead to an improved understanding of rock behaviour and improved methods of underground analysis and design. For the shorter term, a formalised ground control plan was developed, the principles of which may be applied to other types of projects.This paper summarises the status of underground design and construction for nuclear waste repositories and presents some details of the ground control plan and its individual elements.

Jan 1, 1988

By Wright S, Rogers L. J, Precious T. H

Brown coal and its char were investigated as substitutes for petroleum coke in the manufacture of anodes for Hall-Heroult cells. The char, which had been densified by several techniques, was made into compacts with various binders and the anodic consumption determined during electrolysis. The results were an improvement on previous work, but the anodes still fell short of acceptability for use in aluminium smelters because of intractable microporosity. Some options for future development have been discounted.

Jan 1, 1986

By Propser M, Szekely J

Flow maldistribution in the iron blast furnace has been studied analytically by the use of the vectorial form of the Ergun equation and experimentally via packed columns and a cold model of a blast furnace. Experimental results are presented showing the effect on fluid flow patterns of the following types of nonuniformities in a packed bed: the increased voidage at the wall ("wall effect"), the decreased voidage at the interface between layers of materials with different sizes and shapes, and the differences in resistance to flow of bulk regions of a column with different sizes and shapes. The proposed theory is applied to the calculation of fluid flow patterns for these nonuniformities. Velocity profiles, as calculated from these flow patterns, were found to agree reasonably well with experimental measurements obtained via hot wire anemometry techniques for laboratory scale packed columns. Calculated fluid flow patterns are presented for blast furnace burdens which show how flow patterns are affected by (a) coke segregation and (b) the relative differences in resistance to flow between coke and oxide pellet layers. For the cold model study, calculated flow patterns are presented based on photographs of a given burden distribution. The velocity profiles calculated from these flow patterns were found to agree reasonably well with the velocity profiles measured from the cold Model.

Jan 1, 1975

By Eddy B. W, Washusen J. A, Wulff R. T

The State Electricity Commission of Victoria (SECV) has been con- tinuously involved in the extraction of brown coal from open cut mines in Victoria's Latrobe Valley for over 60 years, but have not completed a major mine. Detailed consideration for rehabilitation at this stage has only been able to be given to overburden disposal areas. Increasing interest in rehabilitation in the 1980's led the SECV to review its existing policies and practices and to embark in 1985 on a public consultation process to establish an agreed and accepted policy. This was extended in 1986 to the consultation process for the rehabilitation planning for the Mor- well Open Cut External Overburden Dump. This paper covers the con- sultative process developed and the lessons learned by the participants.

Jan 1, 1989

By Regan R

Appin Colliery mines the Bulli Seam with a gas composition of 98.5% methane and 1.5% carbon dioxide. Relaxation of the strata generally occurs to below the base of the Wongawilli Seam, some 40 m below the Bulli Seam, and approxim- ately 125 m above the Bulli Seam, for longwall face widths of 135 m or more. Previous exper- ience showed that when longwall faces were mined for a distance approximately equal to the face width, the mine ventilation could not provide sufficient dilution due to methane emissions from the underlying measures. Postdraining downholes were drilled to intersect the Wongawilli Seam below the operat- ng longwall. These holes were connected to an underground to surface gas range and various suction levels were applied to improve gas drainage. The resulting gas flow rates and purity from all the downholes were regularly monitored and peak flows in some holes exceeded 160 1/sec. The surface plant drained almost 20 million m3 of gas for the period July 1981 to January 1982 at an average methane purity of approximately 70%. Distinct patterns emerged for different downholes from curves illustrat- ing their variations in flow rate with distance subsequent to passage of the longwall face. The difference between free flow characteristics and those obtained with the application of

Jan 1, 1982

By D W. Airey

Frictional rock bolts are widely used because of their low cost. However, they have a thin wall section that makes them prone to corrosion, and they cannot be relied on to provide long-term ground support. It is difficult to assess the capacity after the bolts have been installed as they can only be pulled out if this has been allowed for during insertion. The questions of how long can the rock bolts function effectively and the effectiveness of various surface coatings, which can have significant cost implications are, investigated in this study.A series of accelerated corrosion tests have been performed on frictional rock bolts. The rock bolts, typically 900 mm long, have been inserted into concrete cylinders produced using a styrofoam insert to create the hole for the bolt insertion. Strata rock bolts with four surface coatings have been tested: uncoated black steel, galvanised, enduro (plastic coated) and coated with a proprietary aluminium/zinc alloy. Tests have been performed on two diameters of bolts. Following insertion of the bolts, the concrete cylinders were placed in a large drum filled with saltwater and current was applied to accelerate the corrosion process. The rock bolts were then extracted at various times after the commencement of corrosion. Comparison of the insertion and extraction resistances shows that corrosion initially increases the bolt resistance and that substantial section loss is required for the bolt resistance to drop significantly.CITATION:Airey, D W, 2014. Laboratory corrosion tests of frictional rock bolts, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 257–262 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

Mr. Bradford said: - On assuming this chair, which has been oc- cupied by so many gentlemen of conspicuous ability, my first words must be an expression of the gratitude I feel for the honour you have done me in electing me to be your President for this year. When considering the subject matter of this address to you to- night, quite frankly may it be stated that for a long time I was on the horns of a very great dilemma, for while I could discourse on the modern political trend in relation to our industries at great length, it appeared to me that this was not the place for such a discussion.

Jan 1, 1987

I must tell you at the outset that I come to this conference deeply disturbed at the `role of Government in international dealings in mineral and energy resources'. I am disturbed by the confusion that now passes for policy. I am disturbed by the short- range view of critical problems taken by a majority of Governments. I am equally disturbed by the even shorter range of view taken by a growing army of industries. Many of them clamour for Governments to solve their problems in a specific way, with little regard for any other sector but their own-and with even less regard for the fact that every time a Government takes over some of their responsibilities they surrender some of their freedom. I would not say that longer range views don't exist. But I would say that they don't prevail at the present time. Instead, we are seeing the con- stant development of many policies for individual problems which don't tackle the fundamental causes. We must get back to basics without delay.

Jan 1, 1978

The first stage in process design for coal preparation is a study of the coal seam and its associated features followed by an examination of the mining method to.be employed and the coal market requirements. Normally benefication is based upon the differences in relative densities of the coal constituents and asso- ciated ash forming components. Since initial liberation is obtained at a relatively large particle size, the size to which coal is crushed is more subject to the market requirements than to liberation studies. It is possible to estimate energy requirements for comminution and recoveries and product grades can be cal- culated following the interpretation of standard laboratory tests. Numerous units are available for the separation and concentration of the components of run of mine coal in- cluding jigging, dense media separators, and for the finer particle size fractions, flowing film separators, dense media cyclones and froth flotation.

Jan 1, 1975

Effective pre-splitting is a key feature of wall control blasting. Most mining operations use historical designs or rules-of-thumb for designing pre-split blasts. If productivity and safety benefits are to be gained, these methods need to be improved in order to accurately predict pre-split performance. This will become more pertinent as overburden depths increase, placing more demands on the pre-split operation. A classical qualitative quasi-static description of pre-splitting (Kutter and Fairhurst, 1968) is presented and it is shown to give some useful insights into the pre-splitting process. In particular, it is clear that the time interval between the initiation of adjacent pre-split holes is a very important factor. In terms of this analysis, it is shown that current techniques which employ detonating cord as the surface initiation system are not optimal. A static quantitative model for pre-split design which has been widely reported is then discussed and its simplifying assumptions and their implications are examined. It is shown that several of the assumptions may be reasonably justified in the light of real pre-split results. It is concluded that the model should yield conservative designs. For this model, the key calculation of the blasthole pressure that is needed to determine the required explosive charge is highlighted. Popular methods employed in the literature for describing the expansion of real detonation products are shown to be inappropriate and an alternative method using the non-ideal detonation code, CPeX, is proposed.

Jan 1, 1995

Kamhalda is located within the Yilgarn Craton of Western Australia, specifically in the Norseman - Wiluna greenstone belt. Numerous nickel sulphide deposits have been mined at Kambalda with I I mines currently operating. For several years, a program of in-mine geophysics has been operating at Kambalda, with downhole electromagnetics (UHEM) one of the key techniques used. Three case studies illustrating the uses of UHEM in mines are presented here. In the first example, the Helmut South deposit was discovered as the result of an extensional exploration program. The first drill hole in the program intersected ore width and grade mineralisation at around 760 in depth. Two subsequent holes intersected subgrade mineralisation. DHEM surveys were completed in each of these three holes, with anomalies recorded indicating that a large conductor was located directly south of the first hole. The next hole intersected this target, for an intersection of 21.6 in at 3.5 per cent Ni. DHEM continued to play a role as the exploration program proceeded, providing drill hole targeting based on anomalous responses recorded in each drill hole. In the second example from Carnilya Hill, old drill holes were surveyed with DHEM in order to search a large section of prospective contact for massive ore pods. An off-hole anomaly was detected and subsequent mining discovered a small but high-grade pod of ore which was extracted for a considerable profit. Carnilya Hill has limited reserves and discoveries such as this, assist in keeping the mine operating. In the third example from Victor, a program of drilling intersected thin ore profiles in an interpreted flanking position. Without massive ore close by, these intersections probably do not constitute economic mineralisation. DHEM surveys of three holes did not detect any conductors. The area is now regarded as sterilised of significant massive ore and exploration efforts and dollars can be focused in other areas. These three examples demonstrate the type of successes that can he achieved through the use of DHEM.

Jan 1, 1997

By McCarthy PL

Widespread interest in reopening Victorian gold mines, regenerated by increased gold prices, has highlighted the technical problems prevailing. A combination of historical lease legislation, minimal recent mining activity, forms of mineralisation, high insurance rates and tortuous approval requirements for mining mean the potential investor assessing an old mine must address a wide range of technical problems. The requirements for establishment of ore reserves and attraction of capital for mine development are fundamental. Underground reef mining was historically generally on a small scale, and as mining on many fields ceased about the turn of the century, past geological and production records cannot be correlated to personal experience and comment. The impact of modern mining technology on future reef mining will be to reduce operating costs and significantly improve historic metallurgical recovery. Roth these are commensurate with increased capital costs. Workers compensation rates currently applicable in Victoria are many times higher than in other states, adding significantly to operating costs. Establishment of a pilot plant testing facility in central Victoria would provide an invaluable service in treating bulk samples essential for grade and recovery assessments of Victorian ores.

Jan 1, 1982

By Guarascio M, Massacci P

In process simulation, more reliable prediction of industrial results and evaluation of data for design purposes and process optimisation may be attained by the combined use of: the modelling and simulation of ore characteristics, and 2. the modelling and simulation of the process. It is well known that geostatistical methods allow the defining of models of orebodies in which the variables considered are the grades of the valuable components. These models are proper for reserve estimation, geostatistical contouring, design and simulation of the exploitation method, and, in addition, for evaluating the variability of the ROM which is expected to be fed to the processing plant. However, no data are normally incorporated in the orebody model in order to evaluate the ore characteristics relevant for a reliable process simulation. The procedure for process simulation aimed at predicting plant results normally used so far consists in collecting samples from different orebody sites and building up a so-called 'representative sample'. On this sample, the ore characteristics (eg liberation, washability, grindability, etc) and the processing tests are referred to as the 'average behaviour in the orebody', assumed constant. A more reliable methodology consists in collecting samples from different orebody sites, in performing tests to characterise the samples from the point of view of the process (ore patterns), and in using synthetic parameters (process features). The values of the parameters are processed using geostatistical methods in order to develop a model for simulating the feed to the process. The estimation may thus be referred to the amount of recoverable minerals instead of to the existing minerals. Furthermore, the selection of the processes, the sizing of equipment and the design of control devices, as well as the prediction of results, become more accurate and reliable.

Jan 1, 1993

By Mozley R

Contaminated sediments are a multinational problem. A crucial factor in solving an environmental problem is knowledge of, not only the amounts of polluted soil, the contaminants involved and their concentration, but also the historical background of the problem. Processing polluted soil is a tailor made activity based on rational decisions resulting from a detailed treatability study. Lack of information about characteristic properties of a specific sludge/pollution combination is the main obstacle in the route from first ascertaining that a particular harbour subsoil is polluted, to final identification of the full scale treatment plant. In the first instance, information must be generated regarding the distribution of pollutants in relation to the distribution of the original geophysical components. Based on this information rational decisions can be made on separation at a particular cutpoint and what sequential techniques should be involved for a certain fraction. For this purpose a `fingerprint method' is presented especially developed for investigation of polluted soil and sediments. The heart of the fingerprint method is a series of sequential hydrocyclone separations, by which a series of products is generated. The objective of the fingerprint method is to select an optimised treatment procedure in which the pollutants are concentrated in as small a volume of material as possible, leaving the bulk of the material clean. The pollutants can then readily be destroyed or isolated from the environment. The philosophy and advantages of the fingerprint method are demonstrated for a harbour sludge containing heavy metals as main pollutants. Hydrocyclone separation combined with flotation of both the coarse and fine fraction resulted in reusable and dischargeable products. Flotation of the fraction of fines was carried out by means of an experimental flotation cyclone enabling the selective recovery of mineral particles with diameters less than 10 microns. The overall conclusion is that design and engineering of treatment flow schemes for polluted dredged materials is a tailor made activity based on rational decisions resulting from the fingerprint information.

Jan 1, 1993

By M S. Manono, K C. Corin

The optimisation and process developments surrounding the beneficiation of Cu-Ni-PGM ores is of fundamental importance when considering the continued rise in global demand for these precious metals. The selective sequential flotation of these ores is accompanied with various processing challenges such as the successful separation of the Cu-Ni-PGMs from non-sulfide naturally floatable gangue and pyrrhotite. Reagents such as sodium iso-butyl xanthate (SIBX) and sodium carboxymethyl cellulose (CMC) have proven to significantly improve the selectivity of the flotation process in their respective roles. The use of recycled water with abnormal inorganic electrolyte concentrations can modify the selectivity of these reagents, as ions may adsorb onto minerals such as pyrrhotite, thereby hindering or promoting the hydrophocity and floatability of pyrrhotite. Process water quality effects on the behaviour of pyrrhotite may have negative or positive influence on the recovery and grades of the wanted Cu-Ni-PGMs as valuable minerals associated with pyrrhotite such as pentlandite may be affected in like manner. Thus, the impact of concentrator process water quality on the behaviour of pyrrhotite needs to be determined. In this study synthetic process water at various ionic strengths was investigated against various CMC dosages to understand the behaviour of pyrrhotite during the flotation of a Cu-Ni-PGM Merensky ore in a batch flotation cell. This study showed that pyrrhotite grades increased with an increase in CMC dosage for fixed ionic strengths whereas the recoveries of pyrrhotite increased with an increase in ionic strength until 3SPW, then a trend of a decrease in recoveries was seen with 5SPW resulting in the lowest pyrrhotite recoveries. Furthermore, this study showed that moderate CMC dosages of 100 g/t resulted in the highest pyrrhotite recovery for all four ionic strengths of synthetic process water tested. It can be said that to maximise value recovery from Cu-Ni-PGM ores, understanding the behaviour of pyrrhotite against degrading water quality and reagent suites could be of paramount importance given the sensitivity of pyrrhotite to oxidising chemical conditions.

Aug 24, 2022

In line with the recommendations of The AusIMM/AMIC Joint Committee Report in 1981 Isa Mine ore reserves are quoted in proven and probable categories (recoverable ore reserves). Internal reporting considers geological mining and extraction reserves in terms of proven and probable categories. Proven reserves are subdivided into detailed and confirmed ore. External reporting includes a possible ore category (not a reserve). The basis for these divisions is the spatial distribution of sampling data. Proven ore is defined by data 80m apart or less and probable ore by data 80m to 150m apart. Within the proven ore category detailed ore is defined by data 40m apart or less and confirmed ore by data 40m to 80m apart. Kriging is used to provide tonnage and grade information for the currently producing 1100 and 1900 orebodies. Kriged cross sections are initially produced to coincide with existing geological sections and are used for stope design. Stope ore reserves calculations are ideally performed at three discrete design stages, which in order of increasing accuracy are: preliminary design (PD), final design (FD) and ring design (RD). At each of these stages Kriged meshes incorporating the most recent sampling information are produced for reserve calculations. Historically derived mining and extraction factors are applied both to global reserves and individual stope reserves to reflect changes in geological and mining conditions as well as the sequencing of extraction. These factorised reserves are then inserted into the computerised reserves inventory system (RIN). Monitoring of individual stope performance continues into the production stage with input from planning, research, survey and production personnel. This allows actual extraction factors to be derived for comparison with predicted factors, providing some measure of stope performance.

Jan 1, 1987

Reliable predictions of the long-term water quality and water level fluctuations in a final void are vital if mine operators propose to decommission final voids in open cut mining operations. The catchments feeding final voids typically comprise a large proportion of coal placed or re-shaped spoil piles. Spoil piles from open cut coal mining operations have distinctive hydrological characteristics, which result in unique run-off behaviour. There is a need to understand the nature of spoil hydrology processes in order to predict the long-term hydrological behaviour and water quality responses of such systems. Preliminary estimates indicate that it may take 20 or more years for a void to flood. It is impractical for mine owners and operators to wait until long-term hydrological and water quality conditions have been established in a void, before reaching agreement with regulators about mine closure conditions. Reliable simulation of the long-term water quality and water level fluctuations in a void are therefore. The adoption of an agreed modelling approach and sharing of results from field data programs could result in the establishment of a database that could be used, with regulatory approval, for assigning parameter values, without the need for a specific data collection program for every individual void. Industry and regulators should agree on the model adopted for predicting post-closure behaviour of spoil/void systems. This will require reliable, robust methods for field data collection. This paper describes the field monitoring, data collection, model preparation and simulations undertaken over a three year period for Australian Coal Association Research Projects (ACARP) Project C7007. It presents the findings of that research, and provides comment on aspects of the project that were undertaken well and on aspects that could have been done better. Limited data is presented in this paper due to confidentiality arrangements with the relevant mine sites.

Jan 1, 2003

By Evans A, Jones O

Surface subsidence resulting from "total extraction" of coal in the Collie Basin first occured in 1987 when Western Collieries Ltd trialled the Wongawilli mining method. Because very little quantitative subsidence data existed for the weak, Permian sediments, a research program was set up prior to the extraction of the first panel. The objective of the study was to be able to predict subsidence characteristics and effects prior to mining future total extraction panels. Attempts at predicting subsidence began using existing subsidence models from other coal mining regions, however, as more site information became available, it became clear that it was necessary to develop a separate, she specific predictive model for the Collie Coal Basin. Analysis of extensive field monitoring data for both surface and subsurface subsidence has produced a series of empirical models which can predict the shape of surface subsidence troughs and corresponding tilts, and strains for rectangular panels and describe the sequences of ground movement from the mine roof through to the ground surface.

Jan 1, 1992

By R L. Verburg, R Johnstone

DeBeers Canada Mining Inc (DeBeers) recently submitted an Environmental Assessment (EA) for its proposed Snap Lake Diamond Mine located in Northwest Territories, Canada. As part of the EA process, a site water quality management plan must be developed. Plan development requires an integrated approach such that the key factors influencing water quality can be identified and managed to minimise potential impact. A system model was therefore developed to simulate the site-wide water quality conditions and mass loadings to the principal environmental receptor of concern, Snap Lake, during operations and post-closure. Requirements of the simulation included integrating hydrology, geochemistry, hydrogeology and site management practices in a dynamic way. A unique feature of the site was the need to accommodate a complex flow system that included a feedback loop between lake water and mine water. A system model was constructed using the GoldSim software package that integrated on-site water quality and flow measurements, as well as results from independent groundwater flow and geochemical modelling efforts. The GoldSim model simulated concurrently the movement of 39 solutes through the subsurface mine and surface facilities. Solute sources considered included four different waste rock and tailings types, explosives use in the mine, treatment plant discharge, and recycled process water for dust suppression. Separate solubility constraints were identified for different regions of the flow system (eg underground mine; treatment facility; surface water bodies). Kinetic test data were used to derive temperature-dependent rate constants for use in calculating mass inputs from surface sources such as waste rock piles. The model generated water quality estimates over time for a variety of management scenarios at several potential discharge locations. The integrated approach used by the model was effective in identifying the significance of key factors influencing overall water quality such as explosives use, mine water inflow rates, waste rock reaction rates, site/mine management options, and effectiveness of treatment. The model provides an example of an effective tool for comprehensive, integrated system evaluation and management.

Jan 1, 2003