Search Documents

By R Blair

The Domain and Burnley Tunnels, which are major features of the Melbourne City Link Project, are MelbourneÆs first road tunnels. They are 1.6 km and 3.5 km in length respectively and are being constructed through a variety of ground conditions. Deeper sections of the tunnels have been driven through the Silurian mudstone which underlies Melbourne. Other shallower sections of the tunnels pass through a variety of ground conditions including silts, sands, clay and rock and have been constructed using both top-down and bottom-up cut and cover construction techniques. The Yarra River Crossing is a 140 m length of the Domain Tunnel which crosses under the Yarra River on a relatively shallow alignment. The crossing of the river using cut and cover techniques was identified in the early stages of design development as being one of the most challenging stages of the works on the Southern Link. The prevalence of varying geological conditions combined with the need for maintained traffic and stream flow conditions provided a demanding and often conflicting set of criteria for which there appeared to be no one clear solution. A team of designers, constructors, estimators and specialist contractors were involved in a concept evaluation and risk analysis study spanning a period of approximately 12 months. During this study, four concepts were considered as likely contenders. This paper provides a brief outline of the four concepts addressing their relative merits, disadvantages and risks followed by a detailed description of the adopted solution, namely top-down construction using secant pile walling (east bank) and bottom-up in situ construction (west bank).

Jan 1, 1999

By A Tinnelly

Land disturbed by alluvial gold mining should be restored to a capability or productivity as good as that which existed prior to disturbance.   Effective rehabilitation requires detailed planning prior to mining and must also be closely integrated with the mining operations.   The main constituents of a rehabilitation plan: description of existing site conditions, choice of final land use, establishment of final landform, water management and erosion control, soil reconstruction, revegetation and management of rehabilitated land are briefly described.

Jan 1, 1989

By L Langer, R Simcock, M Davis

Rehabilitation of mining sites helps to achieve the purpose 5(2c) of The Resource Management Act 1991 û æavoiding, remedying, or mitigating any adverse effects of activities on the environmentÆ. The environmental outcomes for recent and current mining operations on the West Coast are variable. There are some exemplary mining operations which are restoring or even improving land use and environmental factors in the region, particularly those operated by the larger mining companies. There are also examples of an exploitative mentality where the environment and land have been severely degraded by mining activities. Technology has been developed to prevent a repetition of the historical destruction of the environment through mining. Failure to rehabilitate mined land is no longer acceptable to the New Zealand public in the 1990s and damages the credibility of the mining industry. Examples of successful mine site rehabilitation to pastoral farming and to production or plantation forestry are illustrated from the alluvial gold mining industry. Planning, sequencing of operations, the utilization of sailor plant growth materials, and aftercare are key factors in successful land rehabilitation to these productive uses. There is also a recent focus on restoring indigenous forests and wetlands at both coal and gold mining sites, particularly for mines on or adjacent to the conservation estate. The results of scientific research and efforts by the industry on techniques for rehabilitating rainforest and pakihi wetland after mining are presented, particularly from the Giles Creek Dunoille Coal Mine. There is a need for further research and trials to apply and extend rehabilitation techniques to other geological and environmental situations, particularly to mines in mountainous areas and to difficult environments like the coal measures ecosystems of the plateaux above Westport.

Jan 1, 1996

A New Cell for Electrochemically Aided Flotation

Sep 13, 2010

By K Williams, W Chen, J Miller

The flow function of an iron ore material governs its flowability characteristics in material handling chains within the resource industry. A uniaxial compression test is able to obtain a flow function more rapidly comparing to the Jenike direct shear test; nevertheless, the results often exhibit lower rankings using the former method. This study aims to investigate the fundamental stress states within the test specimen that lead to this phenomenon, and to introduce a new uniform density specimen preparation method for a uniaxial compression test, in order to achieve comparative flow functions as for a Jenike direct shear test. The minimisation of the wall friction effect and achievement of the critical state when preparing a uniaxial specimen are explicitly discussed. Experimental investigations on flow functions of a suite of Australian iron ore samples were conducted using both the uniform density uniaxial compression test and the Jenike direct shear test. Results from both methods were found to be comparable, providing the specimen exhibits cohesive flow behaviours. The outcome of this research enabled development of a rapid and reliable flow function testing method for cohesive iron ore materials.CITATION:Chen, W, Williams, K, Roberts, A and Miller, J, 2017. Rapid and reliable flow property testing – a modified uniaxial approach, in Proceedings Iron Ore 2017, pp 149–154 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

The Golden Cross mine is situated in a sensitive environmental setting on the North Island of New Zealand, about 150 kilometres south-east of Auckland and about 8 kilometres NW of Waihi. The mine is situated in dipping topography, with volcanic ashes making up soils, fault zones running through the area, and rainfall of about 3 m per year on average. Water management is the most demanding environmental challenge on site, and a comprehensive programme has been put in place to address tailings deposition, long term tailings storage, and water treatment during and after operations.   The tailings impoundment is built with an underdrainage system that collects groundwaters and waters that seep through the impoundment. The embankment and impoundment are both built to withstand the Maximum Credible Earthquake and the Probable Maximum Flood. Tailings are treated to remove cyanide and to decrease metal solubility to reduce long term risk to water quality after mining. A state-of-the-art water treatment plant is utilised to treat water from the underdrainage system and water decanted from the top of the tailings pond and stormwaters to remove residual cyanide and metals to extremely high standards with a great deal of reliability and at reasonable cost. Closure of the facility addresses long term post mining water quality issues, and rehabilitation of the area with wildlife habitat as a priority.

Jan 1, 1995

Kinetics of Reclamation of E-Waste by a Bioleaching Route

Sep 13, 2010

By G Bubner, C Gaughan

Magnetite mineralisation within the South Middleback Range has been known since the early 1930s; however, it was not until 1989 that BHP (then owners of the Middleback Ranges mining leases) drilled 10 700 m of diamond core into what was then known as the Iron Duchess low-grade deposit. In 2002 a review of Iron Resources left in the Middleback Ranges and the identification of downstream processing benefits using magnetite as a primary feed source led to the commencement of an 18 000 m resource drilling program of the high-grade core of the Iron Duchess low-grade orebody (renamed the Iron Magnet deposit). This paper describes the geology, processes and procedures used since drilling recommenced in early 2003. The Iron Magnet deposit is located 53 km southwest of Whyalla in the South Middleback Range, South Australia. It is a Paleoproterozoic stratabound magnetite deposit that lies down-dip and lateral to the Iron Duke hematite deposit, hosted within the Lower Middleback Iron Formation of the Hutchison Group meta-sediments within the Cleve subdomain of the Gawler Craton. Magnetite bearing host units within the Lower Middleback Iron Formation can be divided into a æmixedÆ basal sequence, a lower iron carbonate unit, a middle iron talc unit and an upper iron silica unit, all units grading up sequence and laterally into one another. The magnetite mineralisation is hydrothermal in origin. The strongest consistent mineralisation coincides with the iron carbonate unit, and the hematite orebodies of the Iron Duke are interpreted to represent up-dip supergene enrichment of the same unit. The Iron Magnet occurs within a large-scale parasitic syncline-anticline pair on the west limb of a larger syncline. Major bounding north-south shear zones occur on the east and west sides of the deposit. Cross-cutting west-northwest, northwest, northeast and east-northeast trending faults displace mineralisation. The commencement of drilling in 2003 lead to the migration of geological and geochemical databases, re-logging and re-assaying of all old cores that intersected the deposit, updating of logging codes and procedures, and strict Qa/Qc procedures to ensure the study satisfied JORC standards. External consultants were used for auditing and bench marking. The strong geophysical responses of magnetite and the wealth of close spaced ground magnetic and gravity data already completed over the Middleback Ranges allowed for refining of drill hole targets for the drilling program. It also provided an indirect method for ascertaining magnetite grade and tonnage volumes.

Jan 1, 2005

The Hyde-Macraes Shear Zone (HMSZ) is low angle, duplex thrust system that has developed in a graphitic pelite schist within the Otago schist belt, New Zealand . At Round Hill lateral ramps have developed parallel to the movement direction between+ the footwall and hangingwall shears. These structures exhibit normal oblique-slip displacement which has been an important mechanism for creating space in an otherwise compressional system. Gold-bearing quartz veins were emplaced along the boundary shears and lateral ramps during thrusting. Gold within the lateral ramps is coarse (up to 300 microns) however hanging wall cataclasite development in the boundary shears after the gold was deposited has reduced the grainzise of most of the gold to less than one micron. This bimodal gold distribution has metallurgical implications with respect to the maximisation of gold recovery at Macraes.

Jan 1, 1993

Investigation on Comprehensive Utilisation of Nickel Slag from JNMC

Sep 13, 2010

Separation of Iron Particles from Banded Haematite Quartzite (BHQ) Ore by Selective Magnetic Coating The separation of fine iron particles from banded hematite quartzite (BHQ) has been studied using selective magnetic coating. The BHQ ore assays as 38.9 per cent Fe, 42.5 per cent SiO2 and 1.0 per cent Al2O3. Mineralogically, the ore contains hematite and quartz as the major mineral phases where as goethite and magnetite is present in minor entities. Natural magnetite of very fine size and oleate-magnetite in colloidal form, prepared synthetically in the laboratory are used as the coating material on the surface of hematite particles. The selective coatings of oleate-magnetite on BHQ surfaces followed by magnetic separation studies have indicated that, it is possible to achieve 62.3 per cent Fe with 8.5 per cent SiO2 at 85.4 per cent iron recovery. The recovery of iron values is found to be superior in comparison to the conventional magnetic separation techniques. The selectivity of coating for enhancing the magnetic response of iron particles is achieved by controlling the surface properties of the particle via electrokinetic potential adjustment by controling pH and addition of oleate-magnetite. In the separation process, the effects of pH, magnetic intensity and addition of oleate-magnetite are studied to achieve the maximum grade and recovery of iron values. The optimum separation is observed at pH of 7.5, oleate-magnetite concentration of 0.25 ml/g of BHQ ore and a magnetic intensity of around 0.8 Tesla. The X-ray diffraction (XRD), Infra-red spectroscopy (IR) and UV-visible spectroscopic studies strongly suggest preferential coating of magnetite on hematite surfaces. Scanning electron microscopy (SEM) studies have brought out the semi-quantitative features of BHQ ore. The recovery of iron values from a lean grade ore such as BHQ is carried out looking into the future needs of this ore in India for iron and steel making.

Sep 13, 2010

Alluvial gold was found in the Terawhiti area, West of Wellington, in the 1850s. This led to the discovery of reef gold. Periods of minor 'gold fever', company flotations, and mining activity occured between 1869 - 1973, 1881 - 1986, and in the late 1880s, with one final company active in 1911 - 1914. 1n the early 1980s, further field work was carried out. No viable mining operations resulted from any of this activity.

Jan 1, 1993

Effects of Hydrated Mg2+ on KCl Flotation

Sep 13, 2010

By R G. Barker

The NZ Minerals Industry Association has continued to advance the interests of the minerals sector through leading the establishment of a Minerals Industry Advisory Committee, and the preparation of a technology strategy with funding assistance from the Foundation for Research, Science and Technology. The current moves mirror those of more than 30 years ago when a government initiative led to a resurgence of exploration through amending the mining legislation, redirecting Government research priorities and tax changes. The economic and political and commercial environment in 2001 is very different from that of the 1960s and success of these new initiatives depends on the continuing support and involvement of all sectors of the minerals industry, and building an improved relationship with the Government and the public.

Jan 1, 2001

By G J. Fleming

The Miwah prospect lies on the dilational 070¦ trending Miwah Lineament near its intersection with northerly oriented fractures within Pliocene volcanic rocks exposed between a NW trending segment of the dextral transcurrent Sumatra Fault, and the more northerly trending Samalanga-Sipopok Fault to the east. These faults reflect the continued interaction between stresses from the India-Australia plate located to the southwest, and spreading within theAndaman Sea to the north of Sumatra. A system of deep seated faults is believed to have facilitated emplacement of post-Miocene magmas and Quaternary volcanic centres at shallow crustal levels throughout northern Sumatra. Miwah mineralisation is associated with variably dipping structurally and lithologically controlled argillic and advanced argillic alteration. An oxidised supergene leached zone and a recent, thin, unaltered tuff blanket partly overlie the mineralisation. Mineralised zones are commonly brecciated and veined, and display quartz, quartz-alunite, quartz-alunite¦pyrophyllite¦kaolinite replacement assemblages, surrounded by more weakly mineralised, often vugghy quartzalunite¦pyrophyllite¦kaolinite advanced argillic, and argillic zones of quartz-kaolinite, quartz¦pyrophyllite¦kaolinite and smectite-illite-quartz. Propylitic assemblages are marginal to more intensely altered zones. Hypogene copper mineralisation is typified by enargite, luzonite, and covellite. The host mineral to gold is uncertain at present. Rare barite, native sulfur, and ?telluride also occur. Bornite and chalcopyrite have been observed in transported altered rocks in faults. Generally the mineralisation is anomalous in precious metals, locally enriched in Cu, erratic in Pb, and depleted in Zn, with a good correlation between Cu-As-Ag.

Jan 1, 1995

By E Topal

Stopes are used in several underground mining methods. Boundary determination of these stopes is generally based on simple rules of thumb. While several stope boundary optimisation techniques are available, they fail to guarantee true optimum results. The first part of this paper reviews some important stope boundary optimisation studies and proposes a new algorithm to optimise stope boundaries and layouts for underground operations. The second part applies the proposed algorithm to a block model to test its ability to produce optimum results and demonstrate its applicability in a number of different scenarios. The results demonstrate that the proposed algorithm can find optimum stope boundaries and layouts in three dimensions for different stope sizes and economic conditions.

Jan 1, 2009

Some Otago quartz veins display spectacular open-space filling textures indicative of shallow formation. Fluid inclusions in some such veins show that fluid immiscibility occured before or during mineral deposition. This immiscibility or 'boiling' occured at depths ranging from about 3 km to within as little as about 100 metres of the paleo-surface. Temperatures of mineralization range from 190 - 250¦C. Metals deposited in these veins include: Au(+Ag), Hg, Sb and As. Hydrothermal alteration is confined to minor silicifation of immediate wall-rock schist, less than about two metres from the veins. These veins have some similarities to classical epithermal systems elsewhere in the world, although wall-rock alteration is much less developed in Otago. From analogy to these classical epithermal systems, it is speculated that gold mineralisation may be found beneath Otago stibnite and cinnabar localities.

Jan 1, 1987

Many sampling standards arrive at a value for the prescribed sample mass by assuming a specific relation between the sample mass and the relative standard deviation of the fundamental error and assigning a value to the tolerated coefficient of variation. In order to obtain an equation that provides a relation between the minimum sample mass and the particle properties, many different models for the drawing of a sample have been developed. Here, a model for the drawing of a sample is proposed which can be considered to be a generalisation of the model used in GyÆs sampling theory. Using simulations, it is illustrated that the generalised model can lead to a better correspondence with actual sampling processes.

Jan 1, 2005

Advanced Jig Separation of Shredded Plastics The authors have reported that the RETAC jig is very useful in separating relatively low density particles such as plastics, and demonstrated that highly efficient jig separation of plastic components in discarded office machines is possible in pilot-scale tests. To further improve the separation efficiency, a hybrid jig (RETAC jig with air bubbler under the particle bed) which can separate plastics having similar specific gravities using differences in wettability produced by a pretreatment, and a reverse jig (modified RETAC jig for plastics lighter than water) were developed. This paper reviews the separation of shredded plastics using advanced jig separation technology (RETAC, hybrid and reverse jigs). Wettability control of the plastics for the advanced jig separation is also reported.

Sep 13, 2010

One of the most significant problems experienced in land reclamation work has been the tendency of earthmovers to over-compact the subsoils and topsoils. The need for extensive subsoil drainage, because of over-compaction, becomes a very expensive exercise and can be attributed to poor planning. The problem has been addressed both at the Waihi and Huntly open-cast mines through the use of low ground pressure machines in the placement of subsoils and contouring. The use of subsoilers working to contour to aerate the soils is essential to integrate both the sub and topsoils so that significant root growth and drainage is established. Waihi's rainfall (approximately 200 mm annually) and light soils create difficulties in preparing for the final seed bed. A noticeable factor in preparation of the growing medium was the reaction of the lime particularly in the subsoils (damp), from a lumpy, quite heavy texture to almost a seed-bed texture within a period of approximately 72 hours. Also the high incidence of stone and debris which was not apparent in the placement of subsoils meant the job became very labour intensive. This will be overcome with the importation of a machine from the USA. All of the rubber tyred tractors used on these projects are four wheel drive in the 6S-aOhp range which for weight distribution and the safety factors allows for good landscaping techniques. Good engineering practices should ensure that slopes of no more than 3:1 be designed, keeping in mind that the long term planning must allow for maintenance and stock management of restored land.  In the preparation of the final growing medium the equipment used included: Caterpillar 05 LPG and blade; three-four wheel drive rubber tyre tractors; Super flow subsoiler; hydraulic twin spinner manure spreader; discs û two types; harrows; MF Seeder; Cambridge Roller and Duncan Rotatiller.

Jan 1, 1991