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By Brinkmann J. R

In the narrow stopes of South African gold mines, rockbreaking is carried out by drilling and blasting with safety fuse and igniter cord being used as the initiation system. The fuse/gniter cord system is used primarily because of its low cost, however several limitations of this method include: inaccurate delay time, unreliable firing, inflexible application to varied configurations, and the absence of dynamic interaction between holes. Alternative initiation systems that incorporate millisecond timing are being developed to overcome the limitations of fuse(tgniter cord systems. Current investigations by the Stoping Technology Division of the Chamber of Mines Research Organization (COMRO) into the effects of millisecond initiation are being conducted at a deep test site. Experimental blasts using various millisecond delays and the independent firing of holes with fuse/igniter cord are being studied in order to quantify the influence of delay time on the blasting process and to identify the best methods of applying millisecond initiation systems. The effect of design variables such as delay time, hole firing pattern, stemming, and panel layout are discussed. Blast results including throw distance and direction, muckpile profile and rock cleaning times are used in the discussion of different combinations of blasting variables.

Jan 1, 1990

The Woodcutters deposit, 65 km south- southeast of Darwin, N.T., consists of a series of veins of pyrite, sphalerite, and galena with some silver, cadmium, antimony, and arsenic minerals. The veins are hosted by the Early Proterozoic Whites Formation, a sequence of black slates with interbedded carbonate rocks and minor ash tuffs. The known orebodies occur about 300 to 500 metres above the contact of Whites Formation with the underlying Coomalie Dolomite, which consists of dolomite and magne- site. The stratigraphic setting is lithologic- ally similar to that of the Mt. Isa deposit, Queensland. The orebodies are replacement veins occ- urring along fault and dyke structures which are sub-parallel to the axes of a double-nosed faulted anticline. The orebodies are in part associated with two unusual carbonatized lam- prophyric dykes. The dykes were intruded after the fold and its slaty cleavage were formed. The ore has replaced the dykes and host rocks and is therefore late-stage hydrothermal miner- alization. The known orebodies are open at depth. A "bonanza" of high-grade ore occurs at the upper part of the largest orebody and is currently the subject of an open cut mine planning study by a consortium of companies headed by Nicron Resources Ltd.

Jan 1, 1984

The nickel ores mined in New Caledonia for one century are mainly silicate ores. These ores are nickel enriched saprolites, formed by partial weathering of peridotites (predominantly harzburgites and some dunites), serpentinised to varying degrees. Saprolites constitute the lower horizon of lateritic soils, sometimes up to 100 metres thick, developed on peneplains now greatly modified by erosion. Saprolites are generally overlain by laterites, a more weathered horizon, where the main components are iron oxy-hydroxides with a low nickel grade. The structure of saprolites depends essentially on the serpentine content of peridotites and, on the other hand, serpentine minerals may have a high nickel content and, so, represent important nickel bearing minerals in silicate ores. Two types of serpentines can be found in nickel ores from New Caledonia: ò primary serpentines, formed by hydration of olivine at temperatures below 400¦C, during overthrusting of peridotites in late-Eocene (Paris, Andreieff and Coudray, 1979), are generally very abundant; ò secondary nickeliferous serpentines, associated with other sheet silicates in garnierites, are now relatively scarce but garnierites were selectively mined one century ago, because of their high nickel grade.

Jan 1, 1996

Railway cuttings require the highest care in design and construction, as the pro- bability of failure concept does not allow any risks to be taken with hundreds of lives being dependent on continued stability. The usual geological influences on stability such as bedding dip and faulting are often discus- sed, but other major problems may come from the presence of sheet joints, cross joints differential weathering and seasonal or daily changes of ground water level. The design of rail cuttings has taken little note of the problems imposed by cons- truction methods, and low cost quarrying methods may seriously weaken a designed shape. The presence of berms and drainage ditches is often difficult to achieve as blasting imposes cumulative stresses and jointing on rocks. Contractors face difficulties in bidding extensive rock cuttings as variations in rock properties are often concealed and overshoot- ing the toe of a batter can easily occur. Modern blasting methods offer some solutions, but the best guide to safe successful cuttings is extensive investigation and the continued involvement of engineering geology at the stages of feasibility, design, construction and maintenance. Two case histories show the influence of folding, faulting and construction methods in the case of slope failure and slope stability.

Jan 1, 1979

By Kramadibrata S

Over the years many attempts have been made to develop a means of assessing the excavatability of rock. Most of them are based on an empirical rating system while some authorities still propose the use of seismic velocity as a direct predictor of the rippability of a rock mass. On the other hand there are a number of classical models which have been developed to define the cutting force required at the pick or tooth of continuous miners.While these methods have been applied with various degrees of success to the design of excavation systems there is no generally acceptable method of defining the excavatability or cuttability of a rock mass in terms of the machine power required to generate a particular rate of production.The authors have attempted to overcome this deficiency by recording the intact and rock mass properties at a number of surface mines where continuous miners were in use and to use this data to examine the relationships between the relevant dimensionless groups developed from a dimensional analysis of the problem.The results obtained are encouraging and it appears that this new approach to the problem could lead to civil and mining engineers having a means of predicting the cutting power required to excavate rock at a given rate at any site.While this paper does not include a review of past work it refers to a number of key publications which will give the reader an excellent introduction to the subject.It is important to point out that the research work reported in this paper is part of a doctoral research project at Curtin University of Technology on the Influence of Intact Rock and Rock Mass Properties on the Design of Surface Mines. One of the major objectives of this project is to explore the possibility of developing a technique for predicting the excavatability of rock in surface mines at the design stage.This paper therefore commences with a brief reference to the continuous surface miners in use at the test sites followed by some original work by the authors in applying Dimensional Analysis to analyse the macro-performance of mechanical excavators. Following an analysis of the experimental data the authors validate the wider use of the model by referring to its successful application in predicting the power required to excavate rock by continuous surface miners at other sites.

Jan 1, 1995

This paper describes several sources of external dilution affecting the stope walls during underground sub-level and bench stoping. Factors which control ground behaviour such as the geometry of the openings, the influence of geological discontinuities, stress re-distribution and blasting practices are discussed. Crown stope instability due to stress concentrations induced by changes in the excavation geometry, is discussed and the most efficient ways to sequence blasting within a stope are analysed. Effects of undercutting by blasting, blast damage in the near field and cut-off slot blast designs are analysed. The influence of dynamic loading on the exposed walls as well as the practice of blasting fill passes within stope crowns are discussed.

Jan 1, 1995

Statistics show that despite a low lost-time accident rate there is a high fatality rate from falls of ground in pillar extraction work. Investigation of accidents indicates that in many cases the planned ex- traction cycle has been ignored. Better training, supervision, and personnel protection and where possible changed systems are suggested as a means of improving safety and achieving better Results.

Jan 1, 1974

By Perring CS, Hill RE, Barnes SJ, Vallance SA

The Maggie Hays nickel sulphide deposit is located at latitude 32¦ 15 'S, longitude 120¦ 30' E on the Lake Johnston (SI 51-1) 1:250 000 map sheet. The deposit occurs in the Lake Johnston greenstone belt, in the Southern Cross Province of the Archaean Yilgarn Block, 500 kilometres east of Perth, Western Australia (Figure 1). The remoteness of the Lake Johnston greenstone belt and its poor access, restricted previous exploration activities and the full appreciation of the geology and its Ni-sulphide potential. It was not until 1991, when Forrestania Gold NL commenced exploration activities, that the geology of the ultramafic units and their potential to host significant concentrations of Ni sulphides were clearly established. This paper, which describes the geology and the characteristics of the Maggie Hays deposit, is based on the results of exploration by Forrestania Gold NL and a collaborative research agreement between CSIRO Division of Exploration and Mining and Forrestania Gold as reported by Perring, Barnes and Hill (1994), Perring and Hill (1995), Perring (1995 a and b) and Barnes, Perring and Reilly (1995). A comprehensive description of the geology, petrology and geochemistry of the deposit is being prepared for publication by CSIRO (Pemng, Hill and Barnes, in press).

Jan 1, 1996

By J Manuel, R Muddle

The demand for iron ore has increased significantly in recent years, with new iron ore sources being mined to meet this demand. As the composition of sinter blends changes with the availability and cost of iron ore, so too does interest in the impact of new ore types on granulation and ultimately productivity. This paper describes a study into granulating characteristics of seven iron ore types, including various hematite and goethite ores. The effect of ore type on feed moisture requirements, green bed permeability, green bed strength and granule size distribution was examined for single ore blends containing coke, flux and returns. The ore size distribution was varied in these blends and its effect on granulating characteristics examined. It was found that the optimum moisture requirement of the ore was more dependent on ore type than ore size distribution, but ore size distribution (and specifically intermediate particle loading) had a greater effect on green bed permeability. The saturation moisture value for an ore was found useful in predicting both optimum granulation moisture and green bed permeability.

Jan 1, 2005

By Lockyer PC, Reed MR Bartlett PM

Difficult ground conditions have plagued the underground operations at Mount Windarra since mining started in 1974.The ore at Mount Windarra consists of seven vertically dipping, sub vertically plunging ore shoots. The ore zone in which the shoots lie is characterised by moderate to heavy cleavage and the presence of serpentanite. The ore is known to extend to 1100 metres below surface.Long hole open stoping under cover of backfill has been used as the primary mining method at the mine, but its poor performance brought the mine near to closure in 1984. The mine had been closed from 1979 to 1980.

Jan 1, 1985

A review is given of the development of the author's ideas on the relationship of ore occurrence to regional dislocations in the earth's crust, presently identifiable in particular areas as linear discontinuities in patterns of geological and geophysical data. Ideas originating from field observations in Broken Hill were developed in conjunction with three-dimensional kinematic deformation models which were devised to simulate rock structures, and to illustrate their response to assumed linear and planar movements at the scale of mine and regional geology. These led to the study of linear features in the pattern of Broken Hill district geology, and to the observation that the Broken Hill lode occupies a "cross-roads" position at the intersection of regional geological lineaments where they cross through and deflect the host rocks. A genetic association was therefore proposed. The recognition of significant regional lineaments requires special techniques and treatments of field data originally developed for the Broken Hill situation. The subsequent application of the work to the Western Australian shield revealed that known major nickel and gold deposits also occur where the host rocks are crossed by one or more regional lineaments. These lineaments were recognised as part of a continental tectonic pattern of major linear trends with which major ore deposits are associated. The ideas were later used in exploration leading to the discovery of the Olympic Dam deposit at Roxby Downs, South Australia, which is related to regional lineaments.

Jan 1, 1983

By A Fareth

Constructed between 1885 and 1891, the New Croton Aqueduct (NCA) in New York State is a 50 km long (31 mi) brick-lined tunnel conveying water from the Croton watershed north of New York City to distribution systems in the Bronx and Manhattan. Except at two siphons, the aqueduct operates as an open channel conduit from the New Croton Reservoir downstream 39 km (25 mi) to the Jerome Park Reservoir in the Bronx. The remaining 11 km (6 mi) is operated as a pressurised conduit and includes a major siphon, of circular cross-section, under the Harlem River. The aqueduct has a flow capacity of approximately 1100 million litres of water per day (13 m3/s or 290 million gallons per day) and supplies on average ten per cent of New York CityÆs drinking water. The CityÆs water supply system is operated and maintained by the New York City Department of Environmental Protection (NYCDEP). This paper covers the work done during the three main stages of the program to rehabilitate the entire NCA: inspections, design and rehabilitation. It also includes some of the more interesting structural findings of the original construction as well as documents and drawings from the NYCDEP archives. The rehabilitation program has been underway in phases since 1993, with inspections scheduled to minimise outages, allowing this strategic aqueduct to remain in service during critical seasonal periods. The open channel flow section of the aqueduct in the north is horseshoe shaped, with inside dimensions of 4.1 m (13.6 ft) in width and 4 m (13.5 ft) in height. The pressurised section is 3.7 m (12.3 ft) in diameter, and includes a 90 m (330 ft) deep siphon under the Harlem River. A total of 163 million bricks were used in the construction, enough to build a 48 km (30 mi) wall around Manhattan Island, 3 m (10 ft) thick and 15 m (50 ft) high.Between 1993 and 1997 a series of in-tunnel investigations were performed in the open channel portion of the NCA, consisting of field inspection, non-destructive geophysical testing, and coring of the brick liner. Between November 2004 and September 2005, a major inspection program was conducted to assess the condition of the 11 km (6 mi) long pressurised section and all shafts, headhouses and blow-off structures along the entire 50 km (31 mi) alignment. Inspection methods included using an underwater remote operated vehicle (ROV) equipped with sonar and cameras to inspect the deep siphon, fibre optics examinations of probe holes drilled through and beyond the brick lining, and core holes and geophysical inspections to assess properties of the liner and behind-the-liner materials. A water pressure and test grouting program was conducted to assess methods and expected grout takes for the rehabilitation work in the pressurised sections. The rehabilitation program is anticipated to be completed in 2010.

Jan 1, 2008

By Thompson IR, Solomons SS

Underground mining with the cut and fill method has been declining during the past decade or so, being replaced mostly by sublevel open stoping methods. During 1983 the Australian Mineral Industries Research Association Ltd. (AMIRA) commissioned a review of the method, with the aim of compiling the state-of-the-art, indicating future trends and recommending topics for research that would be needed to support this future mining. Mines using the cut and fill method in Australia and three other countries were visited to compile current practices and expected developments.Cut and fill is mostly used where geological and ground conditions are unsuitable for open or caving methods. These range from narrow, irregular orebodies to wide, massive orebodies where pillars are retained in ore. There is significant potential for improvement and further development of the method. It may then be used in a broader range of conditions and for orebodies that may not otherwise be viable to mine.

Jan 1, 1985

Longhole stope overbreak has always been a source of unwanted cost within the underground mining industry, and efforts to control it using various rock reinforcement systems have long been a rock engineering challenge. At the Pasminco Mining Broken Hill Operations trials have been carried out using an innovative cable bolt reinforcement system known as Rib-Roc. The system, based loosely on the Swedish Rib-in-Roc concept, utilises zones or ribs of heavily reinforced rock in the troublesome hangingwall and back areas of longhole stoping. The trials were carried out under a strict qualitative and quantitative scientific stope measurement program utilising rock mechanics instrumentation. Not only did the trial demonstrate the success of the system but data obtained was useful in implementing the system virtually as standard practice throughout the operation.

Jan 1, 1995

By Grant BPM

The lower levels at the CSA Mine have been developed to mine reserves between theNo.7 level and No.9 level.Work on major excavations for the project began during 1982 with the develop-ment of the crusher chamber, on No.9 level. The brows and walls were pre-dowelled to improve stability before mining by mass blasting techniques.At the same time work commenced on theextension of No.2 Shaft from No.7 level toNo.11 level. The shaft was stripped, using hand held drilling, to a raise bored holeand concrete lined to a diameter of 5.5 metres. Plats were developed at No.8 level, No.9level and the loading station.

Jan 1, 1985

This paper details successful implementation of a revolutionary pit access system involving excavation of an 'in-the-wall' ramp at Three Mile Hill open pit operated by Gold Mines of Coolgardie, formerly Goldfan Limited, at Coolgardie, Western Australia. Three Mile Hill is a medium-size, open pit, gold operation typified by hard, competent, fresh rock conditions from near surface. The project involved construction of a haulage tunnel or decline access located in the wall of an open pit in place of a conventional pit access ramp. Works undertaken as discussed herein included excavation, support, ventilation, dewatering, services installation, commissioning and monitoring. Prior to implementation, the conventional hardrock pit slopes and designs were constrained by the presence of infrastructure and a main road to the North and by adjoining leases to the Southeast. The combination of these factors and economic considerations resulted in a decision to proceed with an innovative in-the-wall ramp access system that is believed to be the first of its type in Australia. Back-analysis indicates that implementation resulted in a cost saving of as much as A$3.6 million and increased mineable pit reserves. The paper deals with the successful implementation and operation of the in-the-wall ramp haulage as well as an economic evaluation that is aimed at drawing some general conclusions on favourable conditions for implementation in other mining scenarios.

Jan 1, 1996

By May P. M

The role of chemical speciation in alkaline cyanide solutions is discussed by reference to recent experimental data from the authors' laboratories. It is shown that serious gaps exist in our present knowledge of the thermodynamics of cyanide complexes in solution. Nevertheless, using the available data and the JESS suite of computer programs it has been possible to develop a simplified chemical speciation model for alkaline cyanide solutions under conditions relevant to the gold extraction process. Some possible implications of the model for plant operations are Discussed.

Jan 1, 1991

By LaBrooy S. R, Ritchie I. M

Problems with the cyanidation of copper-gold ores Copper-rich gold ores are becoming increasingly important both within Australia and overseas (Dayton, 1982; Deng and Muir, 1994; Muir et al, 1993; Sceresini and Staunton, 1991; Solis, Hefter and May, 1995; Wall, Hornby and Sethi, 1987). In Australasia alone over 30 copper-gold deposits have been reported (Muir et al, 1993). Table 1 lists several of the deposits that have been processed. TABLE 1 Examples of copper-gold deposits in Australasia. Name

Jan 1, 1997

Truly launched during the 1939-45 war, b¬,osted since by huge increases in demand for food, shelter and manufactures of ill kinds, petrochemicals have rocketed into prominence' all'oVer''th'e world and are accelerating to even greater heights.Manipulation of the hydrocarbons in petroleum or natural gas provides raw materials for a wid.e'variety of plastics, resins, detergents, rubbers, chemical intermediates, fibres and fertilisers. These in. turn.. go into a host of products essential to our way of life.A5 a source of chemicals, petroleum has achieved a high place. because of its abundance, relative.eheapness acid ease "f transport and because it can,be' economically processed.'If a nation's industrial' progress is measured by ' the ' modern yardstick of petrochemical production,'Australia has reasonto be proud, for it now has 1S petrochemical plants worth'156 million, either in operation or under construction.At several locations near Sydney and Melbourne, these plants produce petroleum ethylene, propylene, butadiene and benzene, or convert these building blocks into the three major thermoplastics (polyethylene; polyvinylchloride and polystyrene)-a.nd"S.B.R.synthetic" rubber. "A number bf other imr-ortant petrochemicals, including carbon black, and ammonia, also are made, or-planned...Most petrochemicals find application. in seven principal industries - rubber, fibres, detergents, surface coatings, automotive, agriculture and plastics. They play a .part in many other industries, including mining and metallurgy.In Australia, population growth,.an -incr.easing standard of living, greater industrial activity and the replacement of older materials all should considerably expand the markets for established petrochemical plants and lead to the introduction of new manufactures.Unless thwarted, these positive forces should propel petro-chemicals into a future glittering with promise;' ò 'However, some help for the infant industry seems needed if petrochemicals, while growing with the nation, are to contribute as they can to our national development.

Jan 1, 1962

FOR some reason there is not any extensive literature in print on the electrolytic refining of copper, although the method is in general use in America and Europe. In Australia there are but three plants in existence one small one at Wallaroo, in SouthAustralia; one at Lithgow and one at Port Kembla the last two being in New South Wales. The largest of these is the Port Kembla plant. It is also the most modern, and embodies all the latest appliances and improvements of electrolytic practice.The plant and methods about to be described is that at Lithgow, with which the writer was associated for some years, and the experience gained there may be of interest. Electrolytic refining of copper is one of the simplest operations of metallurgy, but, like all metallurgical operations, it requires constant attention and a large amount of common sense. The man in charge should be endowed with an insatiable curiosity as to why certain things are occurring, and an instinct of cleanliness, whichmy first mentor in chemistry, Mr W A Dixon, once impressed on me was better than godliness.

Jan 1, 1911