Search Documents

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

By Harraway D. H, Draper N

The association of graphite with a fine grained pyrite in the Mount Isa lead-zinc ore was investigated from mineralogical and metallurgical standpoints. The pyrite has been partially or completely replaced by galena and to a less extent by sphalerite, pyrrhotiteand chalcopyrite with the retention of graphite films or inclusions. During lead flotation the graphite imparts a spontaneous flotability to all associated minerals, resulting in a low grade fraction, which we call the carbonaceous fraction, floating with and diluting the lead concentrate. In times of low metal prices this fraction seriously reduces the economic value of the lead concentrate. A flotation procedure was developed to upgrade the carbonaceous fraction separately, producing an economic concentrate and a tailing.INTRODUCTIONThe lead concentrate produced from Mount Isa ores can vary from 20 to 50 per cent lead, depending on the locality in the mine from which the ore is obtained. Variations of this order are independent of ore grade and lead recovery. The large variation is related to the presence in the ore of a variable fast floating low grade fraction known locally as the carbonaceous fraction because of its association with graphite. During conventional lead flotation with sodium ethyl xanthate the carbonaceous fraction floats rapidly and unselectively with normal Mount Isa galena.The paper discusses mainly the examination and treatment of an average carbonaceous fraction, defined here as the fast floating material in the mill feed of late 1956. The ore was drawn from the Mount Isa Black Star orebodies. The fraction represented about 5 per cent of the total ore...

Jan 1, 1961

This is a brief introduction of a sewer pipeline constructed with a pipe jacking method in combination with a 1 200 mm finished inner diameter tunnel boring machine developed for the first time in Japan. The pipeline is located under a national highway running through a densely built urban area and is 185.7 m long and 2.9 m to 3.7 m deep from the ground surface. The geological features along the pipeline show mostly slate and partly silt. The pipeline was constructed with a newly developed multi-application type tunnel boring machine equiped with a fluid transport system. The construction consisted of tunneling by a tunnel boring machine followed by pipe jacking operations. The excavated materials were dis- charged off the tunnel by a fluid transport System.

Jan 1, 1987

Declining from surface provides access, haulageway, ventilation and provision for ser- vices for stoping and development. Three boom jumbos and 3.8 m3 capacity diesel loaders are used in decline development, the majority of which is driven at a gradient of 1 in 9. Primary ventilation is drawn from the mine through raisebored airways and high pressure contra rotating fans provide secondary ventil- ation. To meet schedules a special decline crew was formed on similar lines to a mining con- tractor. The basis of payment for the mining party was changed and the net effect was to accelerate development. Ground conditions demand constant support and this is achieved with chemical anchor rock bolts, multistrand grouted bolts and shotcrete. Major local shear zones are encountered and when they are to be driven through, a combina- tion of the above methods, involving a spiling technique, is used.

Jan 1, 1977

By G Cormack

By designing comminution circuits for mineral liberation rather than the final recovery process and by using high mass pull gravity recovery, the concept of underground processing has become a reality. Gekko has found that many ores respond favourably to fine crushing with either high pressure grinding rolls or vertical shaft impactors which when combined with the InLine Pressure Jig gravity separator and coarse flotation results in a narrow, low-head, compact processing plant that can be sensibly fitted in existing underground openings. The focus on fine crushing reduces the power requirements of the plant to approximately 5 kWh/t for a capacity of up to 20 t/h run of mine ore feed. The use of water recycle systems places no extra load on the mineÆs normal water handling system. GekkoÆs underground processing plant, the æPythonÆ, has been designed to be towed down the decline or lowered down a shaft and is capable of being installed in sloping, non-linear drives for placement close to the working face. The overall benefit to mining companies of this concept has been estimated to be a significant operating cost-saving, lower cut-off grade and a significantly smaller environmental footprint.

Jan 1, 2008

Production of refined zinc (99.95 per cent) at the minesite without increasing greenhouse gas emissions is considered. As an example, exploitation of the full reserve of the McArthur River orebody is proposed, using the existing concentrator, whilst introducing radically innovative smelting technology. Bulk flotation of all the sulphide minerals is followed by smelting in a melt circulation reactor with tonnage oxygen. By smelting the high-energy pyritic concentrate and reacting the evolved sulphur dioxide with near-mine dolomite, a large amount of electricity can be generated. This is enough to supply all the requirements for the smelter itself, an air separation plant and a facility for compressing and liquefying carbon dioxide. Carbon dioxide is disposed of off-shore for enhanced oil recovery or by other means. The reacted dolomite fixes sulphur as an inert and environmentally acceptable solid residue. Treatment by these means leads to virtually zero gas emission smelting. The paper concludes with a vision for the future in which expansion of zinc smelting capacity is seen to be definitely needed.

Jan 1, 1998

By L Soares, W T. Hennies, F Fujimur

Barra Bonita reservoir, located in the Sao Paulo State, Brazil, has been mainly used for local navigation and electricity generation to supply a prosper region in the country. Sand mining activities in that area have an important social and economic meaning for the local community. In this reservoir there are several sand mines that produce around 45 000 m3 of sand a month. These deposits were rich in material used as concrete aggregate in the civil construction. However, nowadays a significant increase in the demand of gravel can be observed, representing a serious productive problem. This material hasnÆt been well accepted by the market and, through the years, it was disposed at open sky in piles as waste deposits. This deposits have caused environmental problems like visual impact, reduction of free spaces outside and inside the mine, source of material to erosion and sedimentation processes in lower areas, flooding as a result of the filling up process in the drainage system, among others. For a lack of an appropriate technological characterisation, this material have been mainly used to pavement internal and external areas in the mine, with lower cost associated. With the purpose of evaluate the usefulness of this material in the conventional concrete, there were conducted several tests in the disposed residue including petrographical, physical, and chemical characterisation. The petrographical analysis and the preliminary results of the study showed that the material reacts with the alkalis that are present in the conventional cement (CP-II-E-32). In order to make the application technical and economically possible a research was developed seeking forms to correct this characteristic by adding special cements with high pozzolana content. The results of the technological, physical and chemical characterisation of the products indicated the technical viability of the use of that material. The study also allowed projecting environmental improvements resulting in the elimination of the waste piles.

Jan 1, 2003

The "Line of Lade", a generic term by which the great Broken Hill orebodies are collectively known, lies in the County of Yancowinna, New South Wales (NSW) at the south eastern extrenity of the Barrier Ranges. As the township of Broken Hill grew to a city (incidentally it was officially named Willyama but by exerting an enterprising community independence which is still evident today it outplayed officialdom and retained its descriptive name), two major areas of population developed, Broken Hill and South Broken Hill. These two main civic divisions are respectively north west and south east of their dividing line, the surface expression of the orebody. See Fig. 1. The border between the States of NSW and South Australia (SA) is drawn along longitude 1410 East whilst the city of Broken hill's official longitude is 1410 28' 14" East which means it is only 50 km from this political boundary. A latitude of 310 57' 03" South contributes to the harsh climate of high summer temperatures which is not mollified by any significant increase in altitude for Broken Hill is only 300 m above sea level.

Jan 1, 1983

In todayÆs demanding business landscape continual change and technological advancement is a given. With these changes there is now, more than ever, a need to ensure sustainable growth in respect of value protection and value adding whilst meeting the pressures and expectations of the societies in which we operate. Traditionally the management of safety has been a very reactive activity in the business, in some cases seen as an irritation and a disruptive process that demands a focus on preventing reoccurrences. This in turn has focused the measurement of safety performance on a range of lagging indicators û æafter the effect managementÆ. Gaining and maintaining a licence to operate is crucial to a sustainable business but as a prerequisite, organisations need to have a demonstrable ability to manage the safety of their people, as well as mitigating the people risk associated with the business activity. A major focus in the last decade has been on the implementation of enterprise risk management programs, where risk becomes embedded in all business systems and processes and the organisationsÆ genetic make up is programmed to analyse and integrate risk management into all facets of the business activity. The management of safety should be no different. One school of thought argues that there are no new accidents, but rather our inability to learn from the past. Others believe that as long as we have an appetite to achieve the unachievable, we will have to continue to push the boundaries, our safety comfort zones and inevitably take risks. Single reliance on highly evolved technical systems, elaborate processes, highly skilled people, safe equipment and safe work environments have shown one thing û they are not sustainable in providing adequate coverage in the business. In analysing a range of factors associated with some of the worst catastrophes of the 20th century, it can be suggested that they were in fact predictable and inevitable and that an integrated approach underpinned by sound risk management systems could have determined a different result. The key to a sustainable approach in the management of safety requires us to look at a multitude of aspects that collectively allow the performance of an organisation to be predictable. To have certainty in the business activities it is necessary to have controls in place that will mitigate the risks normally associated with unwanted events. It is ensuring that human factors effectively contribute to monitoring the planned approach and being able to safely adjust to any variability. In essence this is having the ability to proactively plan for the longer term. The sentiments articulated by organisational leaders echo that safety management is good business. Surely then a good business is a sustainable business, and a sustainable business is one that provides lasting benefits to its stakeholders.

Jan 1, 2006

By K B. Barnard, M D. Urbani

A synergistic solvent extraction (SX) system for nickel and cobalt recovery using Versatic 10 and decyl-4-pyridinecarboxylate was tested with BHP Billiton pilot plant leach solution. Another synergistic SX system for cobalt and zinc recovery was successfully tested using Baja MiningÆs pilot plant leach solutions. Synergistic SX systems have also been developed to separate iron, zinc and copper from nickel and cobalt for Minara Resources and to separate manganese from magnesium and calcium in waste stream for HiTec Energy. The gypsum precipitation problem at the former Bulong operation could have been alleviated using a Versatic 10 and CLX50 synergistic SX system. These synergistic systems have shown high selectivity for target metals over impurity metals and would largely improve SX plant operation. Maintaining a æhealthyÆ organic is very important for efficient plant operation. Careful analysis of plant organic at CSIRO has been used as a tool to pre-empt and/or solve problems in operating circuits. Work performed to assist operators has included assessing plant organic solutions to highlight impurity build-up with time, assessing reagent stability under prescribed operating conditions, correlating organic composition with impurity transfer and crud analysis. An independent estimate has determined that work in this area by CSIRO has provided over $50 M in benefits to the industry.

Jan 1, 2005

Water retention, water loss and delay in tailings storage rehabilitation are major challenges for many Coal Mines. Work by Stewart, Backer and Busch in the early 1980s suggested that there were improvements to be made in tailings dewatering and density by the addition of flocculant. This prompted ACARP, in cooperation with Bulga Coal Management (Xstrata), to initiate a research project investigating the impact of flocculant addition on tailings deposition density, water retention and the tendency for tailings to form surface crusts suitable for subsequent rehabilitation. A polyacrylamide-based flocculant (200 - 250 g/tds) was injected into the tailings line immediately prior to disposal into the impoundment area. The flocculated slurry rapidly released clear water and created a beach due to the immediate increase in deposition density. The deposition density increased from 35 per cent w/w to 61 per cent w/w solids within 24 hours and continued to increase to 75 per cent, seven days after treatment. The water capture at the tailings storage facility improved by more than 90 per cent; water which would otherwise be lost from the circuit through retention and evaporation. The impoundment capacity had nearly tripled due to the improvement in initial deposition density from 420 kg/m3 up to 1163 kg/m3. Four weeks after disposal surface crusts were forming on the storage facility, suggesting that there would be less delay between cessation and tailings storage rehabilitation.

Jan 1, 2008

FaulIing west of the Mount Isa mine is described and is shown to be related to three groups of folds that have been recognized in the area. The first period of faulting postdates the first generation folding; these faulIs are regional faults (tectonic discontinuities) which are folded by second generation folds. The faulting accompanying the second generation folding divides the area west of the Mount Isa mine into four structurally and metamorphically identifiable blocks. The most prominent of these second generation faults is the Mount Isa Fault, which is characterized by a number of distinct zones of intense second generation folding and the presence of localized layers of mylonite. Only limited evidence for brittle deformation has been observed and the major movement appears to be associated with the plastic deformation of the rocks. Confined to the areas of second generation folding in the Mount Isa Fault are numerous third generation kink folds. A detailed description of the Mount Isa and other faulIs is presented together with evidence for their existence. The displacement accompanying this faulting cannot be established because of the complexity of the structure.Postdating these faults and all the folding of the area are minor cross faults.

Jan 1, 1973

By Jury C. G

A decade of expansion and high production targets have led to changes in the number and structure of the Mount Isa Mines Limited work- force. Falls in labour turnover and absenteeism are correlated with two demographic variables, improved selection and placement procedures and home purchase facilities. Some results of recent population surveys are presented and discussed in terms of future housing needs and potential employment problems encountered by school leavers.

Jan 1, 1974

By Hohnen CA, Limerick JM, Hall DRT

An uniquely-designed flash furnace for smelting of nickel concentrate and for the recovering of metal values from the slag generated has been in successful use for nearly six years. Within the last eighteen months the ability of the furnace to treat slag arising from converting operations without significant reduction in capacity has also been successfully demonstrated. Previously, converter slag had been treated separately in an electric furnace. The salient features of smelter developments are outlined and slag chemistry is discussed. The low cost method for the introduction of coal to partially replace light fuel oil is reviewed and total energy requirements evaluated.

Jan 1, 1984

By Hodkinson I, Slight M

Over the last five years Mt Leyshon has matured into a sizeable gold mine by Australian Standards. In the later part of 1990, after commissioning of the 3.5 mtpa CIP Plant upgrade, experience indicated there was potentially additional Mill capacity beyond that being utilised at the 3.5 mtpa rate. Overall throughput was limited by crushing plant performance and high operating costs resulting from the age and condition of the main crushing plant.In addition, mining was being carried out using a mining contractor who utilised relatively small, high cost mining equipment, and on-going exploration success was also indicating that the then current mine plan would result in only a portion of the available resource being exploited.

Jan 1, 1992

By Lane D. P, Malone J. G

The slag fuming furnaces are the major bottleneck in the BHAS zinc production flowsheet. Intensification of the fuming process could significantly reduce this production restriction. Oxygen enrichment was proven to be a means of intensifying the fuming process. This procedure resulted in higher slag bath temperatures, and development work was undertaken towards obtaining accurate slag bath temperature measurement and control. Slag bath temperature measurement techniques were evaluated, with infra red optical pyrometry established as the system with the most potential for continuous temperature measurement and control. Oxygen enrichment resulted in a zinc production capacity increase of 1 000 tonnes per year. An oxygen enrichment technique was developed which both minimized the risk of furnace damage and made the most efficient use of the enrichment oxygen.

Jan 1, 1989

A new bench blast design method and its realization with the assistance of the computer is introduced. The basic design principle is to define a rhomb cell, called fully- fractured zone, through a series of full scale bench crater tests and apply this geometric pattern in multi-hole, multi- row blast design. To illustrate the design method, the optimization process and assessment of blast performance are presented in the context of a case study.

Jan 1, 1992

Studies of the morphology of seamounts within the Hawaiian, Line Islands, Gilbert and Phoenix Seamount groups indicate that the morphology and size distribution of seamounts vary significantly from one seamount group to another. The Line Islands group appears to be the most complicated of all the groups studied thus far. This group is complicated by reactivation of volcanism, which has superimposed volcanics on sedimentary rocks. These seamounts display abundant volcanic features on their summits. Seamounts within the Hawaiian seamount chain display a marked absence of volcanic features due to the . presence of thick carbonate caps. Reef platforms and sealevel benches are very common on these seamounts but are absent from seamounts in most other seamount chains in the central Pacific. Slope angles vary regionally between seamount groups. The minimum slopes are found on Necker Ridge in the central Pacific basin. The maximum slopes are found on ridge-crest seamounts. Roughness increases proportionally with mean slope angle.

Jan 1, 1987

By Booth GW, Robertson IG

The Paddington Gold Mine ties within the Norseman-Wiluna greenstone belt, in the celebrated Eastern Goldfields province of the Yilgarn Block, Western Australia. Regionally, tropical to subtropical weathering has effected development of a prominent regolith and a deep lateritic profile. Detailed examination of the clay mineralogy, largely from a single drill hole which traversed the original Paddington I deposit, outlined three separate, vertically gradational assemblages, which are, in part, rock-type dependant. These include; 1. kaolinite with minur to trace quantities of sericite/illite (0-22m), 2. smectite and/or interstratified clay minerals, together with variable amounts of kaolinite, relic chlorite and illite/sericite (22-81m), and 3. chlorite and sericite (> 81m). Near surface, kaolinitic assemblages may be directly correlated with the intensity of lateritization, whereas smectite and interstratified clays from intermediate zones appear in association

Jan 1, 1989

By Fyodorov A. N, Sorokin M. L, Komkov A. A

The Vanyukov Process is a bath smelting technology, that has been investigated for over 25 years and since 1977 has been in use on an industrial scale. Results of trials that have been carried out at the various pilot facilities over the past 15 years are considered in this paper. Both the main process aspects, design of the pilot furnaces and metal distributions are presented for consideration. Experience of the smelting of copper, copper-nickel, copper-zinc, nickel, lead, and pyrite concentrates is analysed.

Jan 1, 1992