Search Documents

By H Nikraz, E Jamieson, D Cooling

The use of red sand as fine aggregate in concrete manufacture has been investigated as well as the use of fly ash as a cement replacement. The experimental work consisted of casting various concrete mixes including a control and comparing standard properties. Properties tested included compressive strength, splitting tensile strength, flexural strength, modulus of elasticity, water permeability, chloride diffusion, pH dependence leaching and particle morphology. The results show that the concrete strength is not significantly affected when natural sand is replaced completely with red sand. The durability tests indicated high water permeability and high chloride diffusion due to the porosity of the red sand concrete, likely due to the low slump value. Leaching tests did not exceed New South Wales EPA guidelines.

Jan 1, 2006

By Armstrong RW, Middlin B

The development, design, construction and operation of the new Solvent Extraction/BCA process plant at Copper Refineries Pty. Ltd., Townsville is described.The process offers substantial savings in electrical power costs, improvements in plant hygiene, and a lowering of materials handling costs compared with conventional electrowinning technology.The solvent extraction process extracts arsenic from copper Tank House electrolyte using a tributyl phosphate (TBP) - kerosene solvent. The plant incorporates fourextraction stages, two scrub stages, and three stripping stages to produce an arsenic-bearing low-acid strip liquor. This strip liquor is mixed with copper sulphate, and neutralized with ammonia to form a copper (II) arsenic (V) crystalline product, bicupric arsenate (BCA). This product is then used in the manufacture of chromated copper arsenate timber preservatives (Royston 1982).

Jan 1, 1985

By Hatherly P, Luo X, Balusu R, Gale W

Ongoing, collaborative research between CSIRO's Exploration and Mining and Strata Control Technology has resulted in a better understanding of rock failure mechanisms around longwall extraction. Failure has occurred further ahead of the retreating face than predicted by conventional longwall geomechanics theory. In some cases significant failure has been detected several hundred metres ahead of the face position with demonstrated influences of minor geological discontinuities. Shear, rather than tensile failure has been the predominant failure mechanism in the environments monitored. Validating technologies of microseismic monitoring and new face monitoring techniques have assisted the development of predictive 2D computational modelling tools. The demonstrated 3D consequences of failure has assisted in the ongoing direction of the project to further investigate these effects.

Jan 1, 1998

A laboratory investigation was carried out to obtain data on the explosive character- istics of selected coals mined in New South Wales. Seven coal seams were sampled and the volatile matter content of the coals tested varied between 28 and 37 percent. A mod- ified Hartmann apparatus with a volume of 1250 ml was used in the investigation. Dust clou' generation was produced by an air blast delivered radially through a mushroom type valve and the ignition source was a-continuous A.C. spark produced by a 20 000 V, 50 mA transformer. The coal dust parameters invest- igated were the maximum pressure developed, the average and maximum rates of pressure rise at dust concentrations between 200 and 1500 3 g/m.

Jan 1, 1981

This paper looks at the problems associated with surface settlements and other subsidence effects from the underground extraction of coal in relation to consent applications under the Resource Management Act. The main features of subsidence are examined with respect to identifying the adverse effects as defined under the RMA. Particular attention is paid to sites where little or no data is available as in the case of greenfield sites or at mines where new or different mining methods are being introduced. In these situations it is not possible to make accurate predictions of settlements or strains and therefore other factors need to be considered. The long term effects which might occur post mining are examined in relation to mitigation and management options.

Jan 1, 2003

By Gigmai W

Ok Tedi Mine is a high production open pit porphyry copper mine located high in the Star mountains of Papua New Guinea. The mine produces an average of 160 000 tonnes of ore and waste daily at a 1:1 strip ratio. Full scale drilling and blasting began in 1988, prior to which time all material was ripped and dozed.Drilling and blasting procedures at Ok Tedi underwent a major review commencing mid-1989. As a result of a mutual commitment by management at Ok Tedi and the mines explosives supplier ICI, significant reductions in overall blasting costs have been realised. These cost savings are primarily the result of the introduction of air bags, expanded patterns and better field execution.

Jan 1, 1992

Mount Isa Mines Ltd. annually extracts 5.6 million tonnes of copper ore from the 1100 Orebody. All production is by longhole open stoping, with an increasing emphasis on pillar recovery. Drilling and blasting prac- tices have been modified to allow more efficient pillar extraction, with the evolution of a "core and shell" approach. Blast design occurs at the stope design stage, while individual blast preparation is based on detailed ring plans. A programme of blasting research involving surface and under- ground vibration monitoring and fragmentation assessment has been car- ried out in conjunction with production personnel. Drilling and blasting practice in the orebody must continue to evolve with continued research, to suit changing conditions and take advantage of new technology.

Jan 1, 1988

Thiess Dampier Mitsui's Moura-Mine is located in the south-eastern corner of Queensland's Bowen Basin, some 180 kms west of Gladstone. Current requirements of the open cut operation are to drill and blast 25 million cubic metres of overburden per year, consuming some 12,000 tonnes of explosive in order to meet the requirements of the mine's four operating draglines and one overburden shovel. By early 1985 it had become obvious that the existing drill and blast equipment and technology could not cope with the long-term needs of the open cut mining operation. Three 61R drills were in need of rebuilding or replacement. Bulk ANFO trucks working two shifts per day were unable to match the requirements of the four draglines dne to long travel distances, slow discharge rates and their inability to load water-resistant products into the increasing number of wet holes. This paper outlines the significant steps taken to introduce new equipment and technology and the resulting improvements in the mine's productivity and economics.

Jan 1, 1986

The Telfer Gold Mine, owned and operated by Newcrest Mining and located in Western Australia, is currently being expanded. A new underground sublevel cave development is proposed along with an appreciable expansion of the open pit. The Telfer area is generally subject to low rainfall, however, during the wet season cyclonic events can result in sizable rain events, which have the potential to cause substantial inflow. In addition to this, during the first five years (nominal) of the mineÆs life, there is the potential for drainage paths between the pit and the underground mine via decommissioned underground workings which lie directly under the pit. After this initial five year period the pit floor will be mined out below the old workings and will therefore no longer connect to the underground, however cave breakthrough to the surface may start to occur thus providing another water path into the underground mine. To arrive at an optimum, safe solution for dewatering the mine that successfully addressed the above items, a rigorous risk analysis was included as an integral part of the design process. This involved the determination of the probability of events occurring and the consequences of these occurrences. This was compared against the cost of mitigation for the various events. This paper outlines the process by which a safe concept addressing all the issues relating to dewatering the proposed mine has been arrived at. This process included: Establishing the pit catchment areas. These were based on historical run-off data and took into account practical mitigation works. Establishing an Average Recurrence Interval (ARI) based on reference material and historical rainfall data. Utilising a standard approach based on Australian Rainfall and Run-off (ARR) to calculate pumping and storage requirements for the various catchments. Analysing the 20 years of recorded rainfall in the Telfer area to establish the duration, magnitude and sequence of events. This analysis assisted in determining the surface run-off coefficient. Establishing potential water storage areas and determining the risks associated with using particular storage options. Establishing the percolation rate through the cave zone. A degree of uncertainty regarding the percolation rate in the cave zone required that the consequences of using various percolation rates were considered to aid in establishing the rate which was adopted. Establishing preliminary concepts and determining the most economically viable concept. Conducting a risk assessment based on the principles outlined by Australian Rainfall and Run-off (ARR) to confirm that the appropriate Average Recurrence Interval (ARI) had been selected. A risk assessment was also conducted in accordance with client requirements. Establishing the optimum pump station sizes and storage capacities. Establishing the appropriate numbers of duty and standby equipment. By using the foregoing process, which included a number of stages of risk analyses, an optimum dewatering system concept was produced.

Jan 1, 2003

By Bhattacharyya AK

With increasing demand for more efficient production from the underground coal mines in the Southern Coalfields- of New South Wales, their design and operational aspects are constantly being reviewed and improved. One key area in such pursuits is the reliable design of stable and yielding pillars. The current designs of pillars based mostly on experience leads to unnecessary sterilisation of coal or strata control problems. To explore such mine design problems, computer based modelling is increasingly being applied. In the study described in this paper, the object was to determine the particular width of pillars separating three roadways in a panel at which the pillars yielded completely and their loads largely transferred to the unmined coal at the flanks of the panel. This was approached through a computer simulation of the behaviour of the strata around a panel, in which the three roadways were separated by pillars of progressively decreasing width. A computer program called FLAC based on the finite difference method was used to simulate the relevant strata behaviour in vertical sections. The appropriate in situ values of the deformability parameters relating to the coal seam, roof and floor were determined from the back analysis of some displacement measurements in such a panel. The process involved successive modelling of a vertical section through such a panel,starting with realistic values of the parameters and varying them until the measured and the modelled displacements agreed closely. Based on the results of the numerical modelling, the width of a yielding pillar for the given conditions is Suggested.

Jan 1, 1992

The safety in pillar extraction is closely allied to the design features of the pillar extraction system. Considering the conventional supported systems of pillar extraction there are problems associated with complying with the design system outlined. The accident causing agencies and the legislative action to overcome them are im- portant aspects. There is merit in the regularity of support and the limiting of the effects that human error can cause. But new problems and hazards are introduced by this powered support equipment. The comparison of accident experience is difficult due to lack of records and lack of uniformity of approach, but it is clear that powered supports provide a safer system. Every progress in research and practice provides further data to employ in accident prevention.

Jan 1, 1974

By A M. Myrvang, B Nøst, N Q. Trinh, I S. B Bergh

The iron ore producer Rana Gruber AS is situated in northern Norway just below the Arctic Circle, and has been producing hematite and magnetite concentrates for more than 60 years. Since the late 1990s, the major part of the production comes from a sublevel stoping underground operation after many years of open pit mining. Despite moderate mining depth, the operations have experienced considerable rock stress problems due to quite high tectonic, horizontal stresses. To manage the problems, comprehensive rock mechanics investigations have been carried out by SINTEF, a major contract research organisation. This has included in situ rock stress measurements, laboratory investigations and numerical modelling. Based on this and practical experience, satisfactory design of vertical and horizontal pillars was achieved. At depth, the ore width increases from 30–40?m to more than 100?m. This, together with a major planned increase in production, called for a change of the mining method. After thorough investigations and considerations, it was decided to change to sublevel caving, very much like the LKAB system. The development of the new system has been closely followed up by rock mechanics measures, including 3D numerical modelling and comprehensive monitoring of deformations and rock stress changes. To achieve a satisfactory caving of the hanging wall, all vertical and horizontal pillars in the sublevel stoping area had to be removed. This has been a challenging task, and the development of the caving has been slow until recently. However, now the caving develops satisfactorily.CITATION:Bergh, I S B, Trinh, N Q, Myrvang, A M and Nøst, B, 2014. From sublevel stoping to sublevel caving at Rana Gruber, Norway – rock mechanical aspects, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 323–330 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By C J. Larder, S E. Turner

The concept of underground grinding is not new, but to a metallurgist and a mining engineer this could be considered unconventional. The idea of pumping a ground slurry several hundred metres from underground in a single lift could also be considered to present a daunting engineering challenge. Using a practical example of a mine in Australia where the owners have requested not to be identified, this paper challenges the conventional thoughts on these concepts and shows that with basic sound engineering practices the production of a ground slurry from underground could potentially provide significant operating cost savings. The supply of ore from the underground mine is currently drawn from depths approaching 800 m below the surface. The cost of hauling the ore to the existing underground crushing station located 500 m below surface has been steadily increasing. A number of alternatives to reduce the mining and processing unit operating costs were examined by Sinclair Knight Merz (SKM) and the mining company. The most radical of these is the use of hydraulic hoisting of ore at an increased production rate. Numerous questions were asked, such as: How does one get a SAG mill or an HPGR crusher underground? Where does one locate a grinding mill underground? Does the technology exist to pump the slurry to surface in a single lift? What will be the cost benefits? What are the risks involved? The study covered the two main technical issues underlying the potential benefits. Firstly, technical evaluations were undertaken on the pumping technology currently available for single and multiple lifts to surface. Secondly, the issues relating to the feasibility of delivering and locating a SAG mill underground were reviewed. Although the capital costs for this project are significant, the operating cost savings showed a potential payback period of less than two years, and furthermore provide the basis for an increased mine life, especially at lower metal prices.

Jan 1, 2005

Although the bromo-cyanide or Diehl process for the extraction of gold from its ores is used on several of the Kalgoorlie mines, very little information has been published on the original process, and no details are available from the various mines now using it. The following description of the process as carried on at the Hannan's Star plant, where several modifications were introduced by the author, will therefore be of interest to mining men, and it is hoped that some discussion on this paper will provide further useful information to the mining community.The process was first installed on the Hannan's Star mine, where a full working plant was erected by the London-Hamburg Co. In their contract they guaranteed a 91 per cent. extraction on a sulphide ore of 15 dwt value. This was considered a very high extraction at the time, and the plant successfully carried out its work.The new features in the process were the finer grinding of the ore, for which purpose the tube mill was introduced, and the addition of a solution of bromo-cyanide to the vats under ordinary cyanide treatment, whereby a higher extraction was obtained in a shorter time. The main difficulty in the process was the easy manufacture of the bromo-cyanide solution, but this was eventually overcome. The mixed salts now supplied by the LondonHamburg Co. are in every way satisfactory, and are supplied at such a price that the process compares favourably with any other from a cost point of view.

Jan 1, 1907

Ok Tedi Mining Limited commenced construction in mid-1981 of facilities and infrastructure to mine and process gold ore at Mt Fubilan in Papua ew Guinea. Production ofgold began more or less on schedule in mid-1984 although design capacity is yet to be achieved. Due to geotechnical problems, two important items of infrastructure, hydropower and permanent tailings disposal, are not yet in place. Current low metal prices make it likely that copper facilities will be postponed.The deposit compriscs a leached gold capping overlying copper sulphide porphyry mineralisation containing significant gold and molybdenum. Mining is by open pit methods. The soft leached capping gold ore is ripped and dozed, loaded by hydraulic shovel and trucked to a dump pocket. After passing a large semi-autogenous mill of nominal capacity of I, I00 tonnes per hour, the ore is treated by the carbon-inpulp process, with a gravity circuit to recover coarse gold. The final product is 12 kg dore bullion bars.At present, all tailings are detoxified with hydrogen peroxide; after cycloning, the coarse fraction is stored, and the slime fraction discharged into the river system; expected environmental impact is acceptable. Investigations for a suitable dam site for a permanent tailings system are still underway.Peak 'I. hour power demand for Stage I is 17 MW, presently supplied by a diesel alternator power station and a 2 MW mini hydropower plant.Initial access to the base camp at Tabubil was only by air. Eventually a road was pushed through 134 km from the river port at Kiunga (where port facilities have been constructed) and a further 23 km to Mt Fubilan.Roads are constructed of compacted gravel and crushed limestone generally underlain by geofabric. Eight major steel bridges were built.The town of Tabubil has been established, including housing, airport, shops, offices, schools and all facilities.Environmental studies have been extensive and a detailed monitoring program is maintained. Ok Tedi Mining Limited is making considerable efforts to train Papua New Guineans and to foster local business.

Jan 1, 1985

By D McB Martin, A Piechocka, M Jessell, M Lindsay, E Ramanaidou

The Hamersley Basin of Western Australia, approximately 500 km long by 200 km wide, is recognised globally for its rich endowment of iron ore resources. Two types of bedded iron ore mineralisation are recognised: the Proterozoic hypogene martite-microplaty hematite ores; and the more recent Cenozoic supergene martite-goethite ores. Exploration strategies depend on the style of mineralisation being targeted; however, stratigraphy and structure are fundamental controls on both ore types. Therefore, the ability to visualise the 3D geology of the entire basin is critical for the understanding of iron ore occurrences and their relationship to ore genesis of bedded iron ore mineralisation. However, due to the large size of the basin, generating a 3D geological model of the regional stratigraphy and structure has not been possible, or prioritised, primarily due to software limitations. Recent advances in implicit automated geological modelling presents an ideal opportunity to develop a 3D model of the entire Hamersley Basin. The innovative Loop software was used to model open source geological data (ie geological mapping, outcrop orientation data, and fault data) sourced from the Geological Survey of Western Australia. In addition to generating a 3D geological model, information such as stratigraphic thickness and fault offset information was extracted using the map2loop module and demonstrated its application to exploration targeting. This study demonstrates how a basin-wide 3D geological model was used to conduct a regional structural analysis of the Hamersley Basin. The results of this study provide opportunities for other prospective regions to be rapidly modelled in order to enhance the understanding of the geology and improve exploration targeting.

Nov 8, 2021

Remnants of Plio-Pleistocene hot spring systems in Northland, New Zealand contain sulfide minerals, principally pyrite, marcasite and cinnabar. The climate is warm temperate to subtropical, with up to 3 m of rainfall per annum, and rocks are deeply weathered. Decomposition of the iron sulfides in natural outcrops and human excavations results in acid rock drainage with pH typically between 2 and 5, and locally down to pH 1. Deeply weathered basement greywacke is clay-rich and has negligible neutralisation capacity. Some overlying volcanic flows have resisted weathering, and pH is kept near neutral by relict secondary calcite in small areas. Natural rainforest soils commonly have pH between 4 and 5 over mineralised and unmineralised greywacke. Mineralised zones are enriched in arsenic, which occurs in solid solution (up to 1 wt per cent) in sulfides and phosphate minerals. Mercury also occurs in solid solution in some of these minerals, as well as in cinnabar. Base metals are present in low (background) concentrations only. Decomposition of the iron sulfides and phosphates releases the solid solution arsenic and mercury into the acid rock drainage solutions. Arsenic is readily adsorbed on to iron oxyhydroxides formed in acid rock drainage situations, and can be effectively removed from the biosphere. However, this arsenic is released back into the environment if the pH rises, as adsorbed oxyanions become less strongly bound and are displaced by hydroxyl ions. Behaviour of dissolved mercury is similar to that of arsenic but less well understood in these settings. Both arsenic and mercury are readily leached into pH 6 solutions from solid material collected from acid rock drainage sites. These observations suggest that neutralisation of acid rock drainage sites is undesirable in this setting, as arsenic and mercury will become more mobile in the environment. The naturally low pH of 4 to 5 of the forest floor, or even lower pH of natural acid rock drainage, is a preferable management option.

Jan 1, 2003

By S Miller, A Neale

As part of a long-term acid rock drainage (ARD) mitigation study, PT Freeport Indonesia has completed the construction of a highly instrumented, full-scale, experimental, overburden stockpile to further evaluate the behaviour of the waste rock system at Grasberg mine. A total of 24 lysimeters, 30 sets of thermistor strings and 48 oxygen-sampling ports were installed at select locations during stockpile construction. ARD flow rates and chemistry have been recorded since the start of overburden rock placement in April 2000. Measurements of in situ temperatures and oxygen concentrations quantify reaction rates and the oxygen pathways that control oxidation kinetics deep within the waste rock profile. Direct field observations show the significance of advective oxygen flow with respect to the onset of oxidation kinetics. Oxygen measurements show that the rubble zone that forms at the base of a waste rock bench provides a critical pathway for oxygen entry to the waste rock profile. Furthermore, rapid oxidation as evidenced by measured temperature increases deep within the panels of waste rock is observed to occur. The observations presented in this paper provide critical insight for understanding the mechanisms and behaviour of full-scale waste rock stockpiles with respect to ARD generation. The results of this program will assist in the future selection, testing and evaluation of appropriate mitigation measures with respect to surface and face treatments to reduce long-term ARD generation. This project is a work in progress, and at least another two-years will be required to fully understand site-specific ARD generation and ARD mitigation mechanisms. This paper will discuss various design and construction considerations, provide an overview of results achieved to date, and some preliminary interpretation of what is happening within the overburden stockpiles.

Jan 1, 2003

By J Barnes

During September 2000, Nabalco management identified the need for a corporate system to deliver its key performance indicators (KPIs). In June 2001, a need was also identified to replace the existing metallurgical accounting system. After a review of the technologies available, the decision was made to develop the systems in-house, in preference to purchasing commercial software packages. This would allow much greater control over the structure, and provide for an iterative, concurrent development process between software and key business developers. This has proven invaluable in the development process. The purpose of the KPI system is to provide a unified reporting tool for all performance indicators. These indicators include production, safety, health and environment, personnel, costs, continuous improvement initiatives and opportunity losses. All of these disparate measurements are brought together into the KPI system and used to determine the performance for each department or area. The general principles of the balanced scorecard business approach (Kaplan and Norton, 1996) are applied to achieve a performance measurement for each area within Nabalco. The new metallurgical accounting system (MA) is a SQLServer database with web page and Excel interfaces. The database is structured around daily inputs of all measurements and calculations. The data is stored and adjustments and reconciliations can be made to this data as required. The focus is on accounting rigour, with all adjustments recorded in the database to allow for full auditing. The structure of the data focuses on the five input/output streams (bauxite in, caustic soda in, fuel oil in, residue out, and alumina out). In-circuit inventory provides a secondary measurement on which to check and calibrate the MA system. The KPI and MA systems were developed using Web technologies and are available to any internet-enabled device with Internet Explorer installed. This removes the need for software rollouts and user training. This will promote the wide use of the systems throughout Nabalco and Alcan.

Jan 1, 2002

By Quintiliani G, Giordano V

A research field of interest and a topical subject with the aim to reduce a considerable amount of coke in ironmaking is the injection into blast furnace stack of hot reducing gas combined with use of auxiliary fuels at tuyeres. In recent years evaluation studies and prelimirfary industrial experiments have been carried out on this subject in Europe and Japan. Even if these experiments seem to confirm the advantages theoretically expected, it appears as useful to cast more light on new problems concerning the improvements of this technique. In this report some aspects are analysed on fluid dynamics of blast furnace process with two gas flows: the main flow coming from the bosh and cross flow of the reducing gas injected in the lower shaft. A research on a blast furnace physical model was made with the aim to obtain information about the phenomena which occur in the full scale blast furnace. This work was carried out on cold models IN and tridimensional) in which the radial gas distribution was experimentally measured. A mathematical model based on gas diffusion was implemented aimed at simulating gas distribution inside the reactor taking into account the number of injection tuyeres. A good agreement between experimental and theoretical data allows for extending results to industrial practice in order to determine operating conditions assuring good performance of blast furnace with high amount of auxiliary fuels.

Jan 1, 1975