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Historically the insurance industryÆs involvement in any project has been relatively late in the process. Often it was a case of the last item to be ticked off the checklist has been to ensure that the insurance is in place. However, in more recent times insurers have imposed more restrictions on the cover they are prepared to provide, which has in some cases necessitated a change in the contracting structure to accommodate the insurance policy(ies). In addition, changing contractual practices have changed the allocation of risk between the various parties involved. This calls for a more proactive approach to the design and implementation of an insurance program for both the construction and operational phases of any resource project. This paper explores how a risk managed approach to the design and implementation of an insurance program for a resource project can align itself with current management approaches to project development. From the authorsÆ experience, this approach is best adopted early on in the project (often in conjunction with the bankable feasibility study) and follows AZ/NZS4360 to objectively examine and compare a wide range of risk exposures of the project in a time-effective manner across the following areas: personnel; environment; general management; compliance û legislation, systems, protocols; asset management; change management; financial impacts to the organisation; products/services; service delivery; and technology. Having identified and then analysed the risk exposures according to common consequence and likelihood ratings the next step is to develop a risk map of all considered exposures. The true value of this approach lies in the development and implementation of a risk treatment plan for identified exposures where the exposure is unacceptable. The plans will lead to the optimal solution to the appropriate risk prevention, risk mitigation and risk transfer options available. This paper also examines other benefits to the project that may arise from adopting a risk managed approach in addition to the ability to design an insurance program which recognises the exposures and the ability of the organisation (and other project parties) to retain risk.

Jan 1, 2007

This paper briefly reviews the history of mine haulage trucks. It reviews producti- vity limitations with respect to size or speed. Changing haul requirements once again create the need for more flexible mechanical drive power transmission equipment. The new equip- ment however is designed to provide extended life between overhauls as compared with previous mechanical transmissions.

Jan 1, 1981

By J Jones, J Blunt

"The requirement for environmental approvals and associated environmental impact assessments (EIAs) is now commonly regarded as a key milestone and body of work during project development. EIAs can be undertaken at various phases during project development, generally either:\ during the scoping or prefeasibility studies, where limited project information is available and the mitigation and management measures of the EIA become a set of criteria and commitments that control project design during the feasibility study, as an iterative approach whereby mitigation and management measures are developed through an integrated process with the engineering team, and measures are included in the feasibility study cost model following the feasibility study, where detailed project design information is available, the cost model is complete, and the EIA is an assessment of a fixed project with limited opportunities for mitigation and management measures to be integrated into engineering design. This paper investigates the advantages of integrating EIA into life-of-mine planning during the feasibility study phase, using the Tampakan Copper-Gold Project (the Project) as a case study. The Tampakan Project is located in the Philippines on the southern island of Mindanao. The Project involves the proposed development of three main areas of infrastructure:a large-scale, open pit copper-gold mine and associated mine site infrastructure (including tailings and mine waste storages, fresh water dam, concentrator, etc) a power station, port and filter plant (PPFP), located approximately 60 km from the mine a pipeline and transmission line linking the mine and PPFP sites.Examples of engineering measures developed through an iterative process to mitigate and manage predicted environmental and social impacts include design of water management infrastructure, modification of the disturbance footprint (eg roads realigned to avoid critical habitat) and realignment of project infrastructure to minimise impacted water catchments.CITATION:Blunt, J and Jones, J, 2012. Integrating environmental impact assessment into life-of-mine planning, in Proceedings Life-of-Mine 2012 , pp 143-152 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 10, 2012

Grey River Gold Mining Ltd commenced dredging alluvial flats in the Grey River Valley in 1989. Previous drilling indicated over 100 million cubic metres of gravels with some 90 per cent of the gold in the bottom seven metres. The dredge built by Rahco, Spokane, was innovative in a number of aspects but particularly in the fact that a separate ladder with a cutter and pump was used to strip the overburden and a bucketline to mine the gold bearing wash below. Metallurgical studies and exploration were initiated when the project commenced. Leasing and environmental considerations were investigated and action taken. While progress is being made, the operation at this stage is not meeting required production and performance. Main problems have been with the stripping system and wear.

Jan 1, 1990

By A Takahashi, Y Uchisawa, M Hayashi, T Watanabe, M Susa

Owing to the deterioration of iron ore, the Al2O3 concentration in iron ore increases, and thus it is important to investigate the effect of increment in Al2O3 concentration on the microstructures of iron ore sinters. During the sintering process, a melt is present in the sinter for only a few minutes, and therefore the microstructure of the sinter doesn’t reach thermodynamic equilibrium. Nevertheless, the formation process of the microstructures can be interpreted and predicted to some extent from the equilibrium phase diagram. This study investigated the liquidus isotherm in the CaO-SiO2-Fe2O3- 5 mass% Al2O3 system at 1240°C in air and the phase equilibria of silico-ferrite of calcium and aluminium (denoted by SFCA) and SFCA-I by XRD (X-ray diffraction analysis) and electron probe micro analyzer (EPMA). The following results were obtained: 1. The ferrite melt region with a high Fe2O3 concentration shifts to the lower Fe2O3 side than the liquidus isotherm in the CaO-SiO2-Fe2O3 system. 2. The compositional region of SFCA extends in the CaOꞏ3Fe2O3-4CaOꞏ3SiO2 direction than the silico-ferrite of calcium (denoted by SFC) composition region with a 0 mass% Al2O3. 3. SFCA-I is observed in the present system, which suggests that the increment in the Al2O3 concentration contributes to the stability of SFCA-I. These results imply that an increment in Al2O3 concentration in iron ore leads to a decrement in the volume fraction of the bonding phase and that the fraction of the SFCA phase increases, and those of 2CaOꞏSiO2 and slag phases decrease in the bonging phase. The SFCA-I phase is also precipitated from the slag with an Al2O3 concentration around 5 mass%.

Jun 19, 2024

By E M. Jones

On 26 June 2000 a hydraulic fill retaining barricade failed at the Bronzewing mine in Western Australia. The barricade failure resulted in the release of 19 000 m3 of saturated hydraulic fill into the mine, which caused the deaths of three miners. Following this tragic accident, the practices and procedures of mines using hydraulic fills came under intense scrutiny by regulatory bodies and mining companies. At this time, the use of hydraulic fill at NormandyÆs zinc/copper Scuddles mine was suspended and waste rock became the sole backfill material in use underground. By 2003, development of the mine adjacent to Scuddles, Gossan Hill had progressed to a point where a self-supporting fill material was required to enable full recovery of high-grade ore. Cemented hydraulic fill (CHF) was identified as the optimal fill type and work began on designing appropriate management procedures and controls to ensure the safe implementation. This work included definition of the fill properties, plant design and construction, reticulation system design, design of stope barricades and drainage systems and fill placement control and monitoring practices. CHF placement began on 16 July 2004 and has continued to date. Significant operational experience has since been gained in areas including plant performance, fill product quality assurance, barricade construction, stope drainage and in situ performance.

Jan 1, 2008

By A Trench, S Ulrich, S Hagemann

A synthesis of reported All-In Sustaining Costs (AISC) for 57 Australian gold mines in the period 2014–2016 reveals for the first time the clear influence of grade upon cost performance, most evident in gold-only underground mines. Past syntheses of costs on a single quarter basis have viewed grade as potentially subordinate to other factors such as production scale, mine geometry, mineralisation style and a combination of other mining-related costs. Better understanding of the grade to cost relationship on both an individual mine and whole-of-portfolio portfolio basis is needed. Insight into the roles and trade-offs between other cost-determining factors will aid the future sustainability of the gold mining sector in Australia and assist in targeting prospects for future resource growth and development. While the overall trend is toward higher-grade mines displaying lower costs and vice versa, the grade to cost functions appear radically different between mines based on time-series data. The median cost of Australian gold production in the final quarter of 2016 was A$1081/oz. The threshold for lowest cost quartile production was A$965/oz. Underground production now dominates Australian gold output – with 71 per cent of ounces originating from operations that are either entirely underground or hybrid pit/underground mines. Scale economies are evident, with smaller mines predominately among the higher cost producers. For mines of equal grade, open pit mines are lower cost than underground operations. Reserves are modest, with a median mine life for underground operations of 4.7 years based on current production rates. Reserve additions at mines are likely constrained not only by the finite nature of mineralisation at each mine but also by the geometrical difficulty of accessing suitable drilling locations to test for reserve extensions.CITATION:Ulrich, S, Trench, A and Hagemann, S, 2017. Towards an understanding of production costs at Australia’s underground gold mines, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 241–250 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By R Brake

The Enterprise Mine (EM) is located at Mount Isa and is wholly owned by Mount Isa Mines Limited (MIM). This high-grade copper mine extends from about 1000 m below surface to almost 2000 m below surface. A recent $400 million upgrade has taken the operation from a production rate of 1.3 Mtpa to a capacity of 3.5 Mtpa. The effects of high surface ambient temperatures in summer, combined with the depth of the mine and high virgin rock temperatures results in heat stress in the working place that, without intervention, would exceed the levels that human physiology can withstand. It would also result in significant decreases in productivity and high accident rates even where work is possible. Moreover, with a very hot and deep mine, the needs of æegressÆ and entrapment of workers during a mine emergency must be carefully considered. Enterprise Mine has taken a æsystems approachÆ to the issue of working productively, healthily and safely in heat. This involves setting limits of thermal stress for workers, understanding productivity decrements when working in heat, establishing productive and healthy environmental targets, developing engineering solutions to meet these targets, creating a well-educated workforce with respect to working in heat and then developing health protocols to ensure workersÆ health is protected. Refrigeration must be added to the mine to provide acceptable and productive conditions underground. By the time the mine is commissioned in 2000, Enterprise mine will have an installed refrigeration capacity of in excess of 40 MW(R). The ventilation engineering principles proven over many years at the other Isa underground mines are tailored to æfloodingÆ the mine with air to remove the heat, which is the main contaminant. This principle will not work at the Enterprise Mine, for reasons discussed below. With the underlying ventilation principle no longer satisfactory, a complete review of the entire ventilation principles and engineering solutions was required for the Enterprise Mine.

Jan 1, 2000

By Brosnan J. G

Simcoa Operations is the only silicon smelter in the region and since the plant was commissioned in late-1989, has progressed from supplying silicon metal to the secondary aluminium market to the current position of supplying in excess of 90 per cent of its production to the high quality chemical and primary aluminium markets. This position has been achieved through the unique advantage which Simcoa has developed within the industry, namely raw materials, people and Simcoa's ability to adopt and use modern technology. A quality culture was instilled into the workforce prior to commissioning which ultimately led to AS3902 qualification in 1992. Simcoa has continued its quality drive through the formation of 'Simcoa's Quality Leadership Process' which is planned to make Simcoa the best silicon producer in the world.

Jan 1, 1995

By D Roldpo, M Vidigal, J F. C L Costa

The local cumulative distribution function (lcdf) of a selective mine unit (SMU) can be estimated by conditional simulations using the statistics derived from the sample points, generating multiple equally probable scenarios. Conditional simulations permit the evaluation of the lcdf at any support, taking into account the spatial variability, ie the variogram, and the two statistical moments, mean and variance, of the conditioning samples. The SMU ore losses and dilution depend on the mining method and mining equipment selectiveness that, in its turn, depends on the predicted block size. A new approach to predict ore loss and dilution was developed in this study. Monte Carlo simulation is used to randomly generate a grade value derived from the lcdf at the mining stage (Zs_mc(t)) in order to make a decision about the SMU destination, ie processing plant (ORE) or waste dump (WASTE). If Zs_mc(t) is lower or equal to the cut-off (Z_cut-off) the block is ORE and, conversely, if Zs_mc(t) is higher than the cut-off (Z_cut-off) the block is WASTE. Considering these binary destinations ORE/WASTE, at the mining time t, and combining each realisation of the simulated random function Zcs_i (X), there are four possibilities for each SMU simulated value: 1. the block was simulated as ore and is actually ore (OO), 2. the block was simulated as ore and is actually waste (OW),3. the block was simulated as waste and is actually ore (WO), and 4. the block was simulated as waste and is actually waste (WW).The dilution factor is given by possibility 3 (WO), while the ore loss factor is represented by possibility 2 (OW). These results comprise the classical classification and reconciliation plots used in the mining industry. The new procedure proposed in this paper is based on the use of all the equally probable simulations to define the ore loss and dilution factors. An application of this methodology was carried out at Vale's iron mine in Brazil. The grade of silica was simulated and 50 multiple equally probable 3D models were generated. The mean and the standard deviation of the ore tonnage (OO + WO) for the 50 realisations, was 233 Mt and 0.5 Mt, respectively. The mean grade increased for the diluted ore (OO + WO) as well as their respective coefficient of variation (CV). The CV increases from 62 per cent in the undiluted ore (OO), to 101 per cent in the ore, considering the dilution factor (OO + WO). The mean ore loss (OW) was 10 Mt and the waste tonnage dilution (WO) was 9 Mt.

Jan 1, 2009

The Ernest Henry Mine is an open pit copper-gold mining operation located in north-west Queensland, Australia. It is owned and operated by Xstrata Copper with a current concentrator throughput of approximately ten million tonnes per annum. The pit will cease mining towards the end of 2010. Extensive surface diamond drilling has confirmed an extension of the orebody to depths of 1000 m below surface. A prefeasibility study was commissioned in late 2006 to investigate underground mining options with the preferred mining method being an inclined sublevel cave. In February 2008 mining of a decline commenced in conjunction with a feasibility study to further investigate the project. Work from the prefeasibility study indicates that an underground crusher, conveyor and hoisting shaft could be utilised to crush and transport broken ore from the sublevel cave workings to the concentrator. The study suggests that a production rate of five million tonnes per annum could be achieved and sustained for up to ten years. Ventilation designs and requirements will form a large section of the feasibility study. This paper will detail investigations of preliminary ventilation network designs of the proposed sublevel cave. Work has been completed using both Ventsim and VumA ventilation simulation packages. Ventsim was used to provide preliminary estimations and suggest alternatives for: surface fan duties;airflow characteristics (direction, velocity, pressure and quantity); andventilation network design in key mine areas. With mining activities reaching depths in excess of 1000 m below surface an analysis of heat conditions should be conducted. The VumA software package was used to model the thermal properties of the ventilation system. This model will provide a basis for the preliminary decisions on refrigeration requirements for the mine.

Jan 1, 2008

By A F. Cropp, D J. Bradshaw, W R. Goodall

Mineralogy and critically the texture of both the ore and gangue phases are of paramount importance in the flotation recovery of copper from porphyry ores. Mineralogy and texture will define the theoretical grade recovery curve for a feed ore. Actual grade-recovery falling below this may be due to texture and gangue influences, whilst desired grade-recovery above this line will not be possible unless the characteristics of the feed are altered.This review discusses examples of porphyry copper deposits where process mineralogy has been used to characterise these textural and gangue influences on recovery by flotation. More specifically, the influence exerted by grain size, liberation, association and elemental distribution is explored. The implications of these on overall plant philosophy and operation are highlighted, along with the subsequent potential impact on recovery.CITATION:Cropp, A F, Goodall, W R and Bradshaw, D J, 2013. The influence of textural variation and gangue mineralogy on recovery of copper by flotation from porphyry ore - a review, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 279-292 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By K Nilsson, D Connelly

Troy Resources acquired the Karouni Gold Project in Guyana, South America in 2014 and immediately proceeded to a Pre-Feasibility Study and project implementation. The study considered two open pit mines feeding a conventional carbon in leach (CIL) gold plant with a capacity of 1Mtpa. The study assumed a total of 2.61 million tonnes of ore with an average grade of 3.84 g/t gold with a recovered gold production of 303,526 ounces over a three year mine life.The project development involved drilling metallurgical test holes, securing second-hand major pieces of equipment where suitable, and arranging shipping to Guyana. The remote location meant logistical considerations were paramount. The plant consists of conventional two-stage crushing with single stage ball milling and a gravity circuit. The tailings circuit includes DETOX.The extremely high rainfall presented challenges with water management and the necessity to dispose of clean water to the environment. The DETOX was also mandatory due to the highly sensitive environment and past history in the area. The criticality of this meant that in the design, any cyanide in the tailings would precipitate in a plant shutdown.Lessons were learned and the project has been both profitable and successful for Troy Resources in a new operating location. In addition, the project has created jobs, delivered royalties and brought new skills into an area where previously there was little current mining activity.CITATION:Nilsson, K and Connelly, D, 2015. Karouni Gold Project from drill core to commissioning, in Proceedings MetPlant 2015, pp 197–206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Z Li, D Chalmers, J M. Tenney

This paper presents the findings and analysis of the investigation of effectiveness of thin spray-on liners (TSLs) as a gas management tool in underground coalmines. The project involves spraying TSL on the area surrounding gas drainage holes whereby the TSL acts as a thin membrane decreasing the permeability of the coal. This restricts air migrating through the coal seam and diluting gas from the drainage holes. There are a number of potential benefits from this technique but key points are that gas drainage holes produce gas with higher concentrations of methane. The design and execution of a field trial to investigate the effectiveness of a TSL on purity of in situ methane from gas drainage holes is presented in this report. For eight drainage holes, the results show an average increase in methane purity by 9.14 per cent and a reduction in air contamination by an average 7.93 per cent. Overall methane flow rate decreased by 27.6 L/s; however, flow rates were unreliable due to poor measuring equipment. For most holes, methane purity was not changed significantly; however, certain boreholes were responsible for most of the variation in methane purity. The boreholes showing a dramatic improvement in methane purity were likely those with intersecting cleats covered by the TSL. If the TSL was sprayed over more area, specifically in areas where the cleats are intersecting with holes, it is likely that purity of methane in the drainage holes will increase.CITATION:Tenney, J M, Chalmers, D and Li, Z, 2015. Thin spray-on liners potential in reducing dilution of in situ gas in underground coalmines, in Proceedings The Australian Mine Ventilation Conference, pp 323–328 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

Solid Energy New Zealand Limited owns and operates the Ohai coal field (Wairaki Coal Mining Licence, CML) in western Southland. The Morley Stream passes directly through the middle of the CML and has required diversion in the past to enable open cast mining to proceed. Solid Energy is evaluating two new open cast pits at Ohai. Commissioning these new pits would necessitate further diversion of the Morley Stream. One of these potential new mines is adjacent to an abandoned State Coal Mines (State Coal) pit and there is an opportunity to substantially rehabilitate this old pit as a corollary to the new mine and the stream diversion project.   Past Morley Stream diversions were undertaken by State Coal and so they predated the Resource Management Act 1991 and the degree of community environmental awareness and involvement that has become the norm these days. Not surprisingly the design and construction of the historic stream diversions was based purely upon mining (operational) and engineering considerations. This led to the stream being diverted in a manner that achieved the clinical conveyance of design volumes of water from points A and B.   Solid Energy realised that the proposed new diversions need to adopt more holistic and environmentally sustainable design principles while also including appropriate mining and engineering constraints. This project involved the design of a 1.7 km diversion of the Morley Stream (median flow of about 1000 litres/second) that would enable progressive prestripping and development of the new mines and would also address final rehabilitation (of the stream), geotechnical risks, hydrological and ecological issues. To address all of these factors the project required a multidisciplinary approach. Moreover, it required a clear understanding of how the mining operational constraints could be integrated with the environmental considerations. A significant aspect of the project was how to take account of fishery instream habitat needs, the resource consent requirements and most of all, the involvement of key stakeholders such as the Fish & Game Council, Department of Conservation, the Iwi and local community in the design process. This was achieved through coordinated consultation and stakeholder involvement in a technical design workshop.

Jan 1, 2005

By Ovchinnikov YN, Novikov VS, Spirin NA, Babushkin NM, Mysik AF, Shcherbatskii VB, Kukarkin AS

Laboratory investigations were carried out to determine the resistance coefficient of the flow through beds irrigated with wetting and non-wetting liquids. A formula was obtained which may be used to evaluate the resistance of the irrigated packing. Quantitative investigations were also carried out on operating furnaces at Magnitogorsk. Continuous measurements of the lower pressure drops were made under different furnace conditions. Pressures were measured in the tuyere space and the bosh region. A significant transient behaviour of the pressure drop was observed in the irrigated zone as a function of the accumulation of the liquid phase in the bosh region as smelting progressed. Additionally, transient processes were also investigated in the upper furnace zones. The basic cause of the transient behaviour was shown to be the irregularity of burden descent caused by the casting cycle. It was shown that the rate of burden descent between consecutive casts reflects fairly accurately the accumulation and drainage of the liquid products as a result of which heat transfer, reduction and aerodynamic processes assume transient character. In practically all cases of casting a decrease in blast pressure and that over the furnace height of 0.2 kg/cm2 was observed. The analyses of radial gas composition at the stock line showed that compositional variations connected with the casting cycle are most pronounced in the central and peripheral regions, whilst in the intermediate regions the conditions are relatively stable. Calculations show that as casting progresses there is a decrease in the gas flow rate at the periphery and an increase in the centre of the furnace. The transient nature of the aerodynamic processes in packings revealed the existence of an appreciable reserve capacity. Elimination of transience was tested on the furnace at Magnitogorsk and improved operating and economical furnace parameters obtained.

Jan 1, 1975

By X Tian, J Forster, A Olmsted, E R. Bobicki, M Goldbaum, D Boucher, C A. Pickles

As the global demand for metal values expands, it becomes increasingly important to create more sustainable mining operations. Consequently, considerable research and technology development is required to produce processes which are both more energy efficient and have a minimal environmental impact. One potential technology is the utilisation of microwave pre-treatment to reduce the energy requirements in comminution. Microwaves can preferentially heat the valuable mineral phases in an ore and the resulting differential thermal expansion leads to the formation of microfractures along the grain boundaries. As a result of the preferential heating, ore competency is reduced, mineral liberation is enhanced, a coarser grind size can be employed, and plant throughput can be increased. Furthermore, microwave pre-treatment can be combined with advanced ore sorting, to decrease the quantity of gangue material processed downstream and hence reduce tailings production. Previous studies on the microwave treatment of ores over the last 30 years have mainly been limited to low power bench-scale studies and there is a paucity of information on pilot and/or commercial scale studies. In the present research, the microwave heating behaviours of over 40 ores have been studied at the bench-scale. These results were used to generate a database, from which a unique classification system was developed. This system was used to rank the amenability of any given ore for microwave pre-treatment. This knowledge can be employed to predict the performance of the ores in the high-power pilot scale tests and thus can be used as a pre-screening tool. The effects of high-power microwave pre-treatment on grindability and liberation were reported. Additionally, the ore sorting potential was evaluated using a combination of X-ray transmission (XRT) and microwave infrared (MW/IR).

Aug 24, 2022

By K Smith

This paper presents an assessment of the Robertson (2010a) method within the CPTu inversion parameter framework of Been et al. (1987), using CPTu calibration chamber data presented by Jefferies and Been (2015) and in other literature to assess the validity of the method, with particular focus on applicability of the method to TSFs (i.e. its applicability to loose silts and silty sands). The assessment demonstrates that although the method estimates values of k consistent with calibration chamber data, the method estimates values of m that are generally 1.5 to 2 times greater than calibration chamber data. As a result of this, the method generally overestimates Ψ for values of Ψ less than 0, and underestimates Ψ for values of Ψ greater than 0. This may result in both overly conservative assessment of materials as potentially liquefiable and unconservative predictions of material behaviour for loose materials.

Jul 1, 2021

At its Port Kembla Plant, Australian Fertilizers Ltd. manufactures Superphosphate and other Phosphatic Fertilizers.Phosphate Rock is received from Nauru and Ocean Island. It contains water insoluble tri-calcium phosphate, Ca3(PO4), to an average of about 86%.It is crushed to pass a 20-mesh x 26-gauge woven wire screen, and is then treated with Sulphuric Acid to give the product Superphosphate with a water solubie prosphate content of 20.5%, estimated as P205. Sulphuric Acid is made by the chamber process. Three sets of chambers are installed, on,e five-chamber set of timber frame work construction and the other two of more recent date, each with four chambers of steel frame work construction. A fourth chamber set is now being built.Sulphuric Acid is delivered for use. at about 70% H2S04, the strength depending upon the rock used.Mixing - The crushed rock and sulphuric acid are mixed in weighed and measured proportions respectiyely in one-ton batches in revolving cast fron pans, mechanically stirred. The mixture, while still slurry, is run into a closed horizontal concrete cylinder (den) where, with the completion of the chemical reaction, it rapidly sets as Superphosphate.Approximately fifty batches are required to fill a den. When full, the den is opened ana the mass cut out by a revolving cutter. The product is elevated and conveyed to any required position in the Superphosphate storage shed, where it dries and matures.Despatch - As required, the Superphosphate is excavated by a two ton grab and conveyed from the matured "dump" to bagging units where it is disintegrated, screened and bagged at twelve bags to the ton. The filled !Jags are closed by machine and delivered to railway trucks immediately.Mixed Fertilizers - Sulphate of Ammonia, Sulphate and Muriate, of Potash, and Blood and Bone are mixed with Superphosphate and thoroughly incorporated to give different mixtures to meet special plant requirements.

Jan 1, 1938

Declines for both access and rock haulage are replacing shafts for mining relatively shallow deposits of down to 1000 m below surface. Where the orebody does not outcrop and where surface access may be restricted, it is often necessary to drive long dead end headings before a connection can be made back to surface and a ventilation circuit created. In hot tropical areas and where large diesel powered equipment is used for mining, heat may also be a problem at these relatively shallow depths. The normal design criteria based on statutory limits and good practice used to evaluate ventilation and cooling requirements in terms of air velocity, dust, gases, diesel exhaust dilution, re-entry after blasting and heat stress are described in this paper. These are then used to design and cost alternative auxiliary ventilation systems that include leakage based on general fan performance curves and typical duct systems. The implications of the current European Community recommendations regarding nitrous fumes are also briefly considered. The actual problem relates to a 2100 m long decline that may have to be extended to 3000 m long without a connection to surface or through ventilation and is located in a hot tropical area where the surface wet bulb temperatures may exceed 25¦C for more than a third of the summer period. Once the preliminary ventilation design is completed, the auxiliary ventilation system can be modelled and simulations undertaken that incorporate heat and moisture transfer routines with the objective of determining the cooling load and amount of refrigeration required. Cognisance is taken of cyclic diesel operations and the thermal flywheel effect of the surrounding rock on the wet and dry bulb temperatures resulting from these operations.A suitable modular cooling system located at the portal is described and optimised with capital and operating costs of both the ventilation and cooling systems provided.

Jan 1, 2005