Search Documents

By R Benton

Since commencement of underground production in March 2006 the Kencana K1 orebody has delivered over 0.9 Mt of ore containing 1.18 Moz Au until April 2009. The Kencana deposits are part of the Gosowong goldfield located on the island of Halmahera in eastern Indonesia. The district has produced over 2.3 Moz since mining commenced in 1999 with the first two deposits extracted by open pit methods. The K1 deposit is technically challenging being a vein style deposit with poor to very poor ground conditions and a relatively low overall dip of around 45 degrees to mine grid east. It is mined under geological control by underhand cut and fill methods utilising cemented paste backfill aiming for 100 per cent extraction. With these conditions the operation was mine limited in the initial two years of production resulting in low stockpile levels for mill feed blending and hand-to-mouth mine to mill production. Mill feed rates have increased from 30 t/h to 55 t/h over this period following business improvement projects while mine production has escalated to match this increase as deeper levels of the deposit are accessed. The operation has now become mill limited. Monthly mill gold production from Kencana has ranged up to 50 000 oz with head grades ranging between 8 g/t and 122 g/t Au on a daily basis. As individual grade control assays can extend into the per cent Au range there are challenges in sampling, modelling, mining, blending and milling the Kencana orebody. At the time of commencement of ore driving in K1 the national geology team had little prior experience in underground mining and systems were in early development. The variances in feed grade and tonnages have been reduced with time as the operation evolves and business improvement initiatives are undertaken to smooth peaks and troughs in ore supply. Two such initiatives in the geology department have added over US$20 M of additional revenue per annum.

Jan 1, 2009

On Monday, October 25th, 1971 at approximately 12.15 a.m. the night shift proceeding underground discovered smoke at No.1 and No-3 cut throughs on the eastern side of the belt heading and in close proximity to the upcast shaft. Attempts to control the fire continued throughout the morning; as the position underground altered various procedures were adopted in an effort to contain and control the fire. Despite these efforts at approx. 12.40 p.m. a sudden change occurred which made it necessary to withdraw all workmen from underground, the vicinity of the Tunnel entrances and upcast shaft. Sealing of the mine at the entrances was the only remaining alternative. Several boreholes were put down to enable sampling of the atmosphere and air temperatures to be taken. This was essential as a guide to determining when conditions were suitable to allow exploration of the area using mine rescue self contained breathing apparatus.

Jan 1, 1972

By G P. W Suyantara, Y Tanaka, T Hirajima, Y Aoki, K Sasaki, H Miki

The effect of sodium sulfite (Na2SO3) on the flotation behaviour of bornite and tennantite is reported in this work. Flotation tests were performed using pure minerals of bornite and tennantite under various concentrations of sodium sulfite at pH 9. The flotation results indicated that sodium sulfite exhibited a depressing effect on the floatability of bornite in the presence of 0.1 mM PAX. However, tennantite remained floatable after the addition of sodium sulfite in the presence of 0.1 mM PAX. The flotation tests using mixed bornite and tennantite confirmed the flotation results of single minerals. Surface characterisation using X-ray photoelectron spectroscopy (XPS) was performed to explain the flotation results. A mechanism is proposed based on the XPS analysis results.

Aug 24, 2022

By V M. Silva, P A. A Martins, V O. Matthew, A L. S Fonseca, E B. Cunha, A J. D Ferrari, E M. S Silva, A C. Silva, D R. T Vilela

The Anglo American phosphate mine is located in the Brazilian state of Goiás and possesses one of Brazil’s most important phosphate rock deposits, with the site being the country’s second largest producer of phosphate rock concentrate. Despite the site having been in operation since 1979, the mining team only started using explosives in 2004 when rocks with greater hardness started to appear in the mine’s geological profile. Rock excavation was previously performed mechanically. Until 2013, only rocks with high hardness were blasted, this following the standard drilling grid that was defined in 2004 without any changes in the blast parameters. The aim of this paper is to show how fragmentation optimisation has yielded positive results at all stages of the production chain, from the mine to the mill passing through an impact hammer crusher, a rod mill and ball mill, operating in close circuit with hydrocyclones.While incorporating the mine to mill holistic approach during the operational integration, the focus was on defining the blasting domains and respective optimal fragmentation and measuring the benefits of blasting in terms of reduction in energy and grinding media consumed in the comminution processes. In the first stage, the blasting team made changes to the blasting parameters and assessed the effects of these changes on fragmentation using computer software and on-site measurements. This generated a database that made it possible to divide the mine into blasting domains. For the second stage, teams from the plant, geology, mine planning and operation departments jointly made comparisons between the performance when processing stockpiles, which only included high hardness blasted ore (20–30 per cent of blasted ore). Changing the drilling grid’s size from 3.0 m × 3.8 m to 2.0 m × 2.6 m for high hardness rock with the presence of silicates resulted in a 40 per cent reduction in the P80 for the blasted material (from 459 to 278 mm), while changing the grid from 3.0 m × 3.8 m to 2.6 m × 3.2 m for high hardness rock without the presence of silicates generated a reduction of 25 per cent (from 270 to 204 mm). There were gains observed from the measurements at the mineral processing plant in terms of specific energy spent on comminution and on the consumption of grinding bodies in the rod mill. There was a measured reduction of circulating load during secondary grinding and a reduction in slime generation.CITATION:Silva, A C, Martins, P A A, Silva, E M S, Fonseca, A L S, Ferrari, A J D, Cunha, E B, Silva, V M, Matthew, V O and Vilela, D R T, 2015. Fragmentation optimisation – adopting mine to mill for reducing costs and increasing productivity, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 363–368 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Woodhouse M, Drew GJ, Andrews DL

The Honeymoon nickel sulphide deposits are located 45 km south of Wiluna in the 2.7 Ga old Agnew-Wiluna greenstone belt in the NE of the Yilgarn Craton (Figure 1). Both disseminated and massive nickel sulphide deposits are present within the deformed and metamorphosed Honeymoon Well ultramafic complex and are hosted by distinctly different komatiitic lithologies (Gole et al, 1996). The deposit styles and host rock lithologies reflect formation in markedly different volcanic settings. Metasomatism has affected parts of the ultramafic complex, including sections of the sulphide deposits, and has had a marked impact on mineralogy and bulk sulphide compositions. The present indicated resource is 158 Mt at 0.71 per cent Ni in four deposits (0.4 per cent Ni cut-off, resources above 300 m depth, December 1995). This includes a massive sulphide resource of 2.5 Mt at 3.36 per cent Ni.

Jan 1, 1996

The Olympic Dam copper/uranium deposit was discovered in 1975 and subsequently commenced production in 1988 at a rate of 1.5 Mtpa using the sublevel open stoping mining method. In the following five years the operation underwent two optimisation programs that have increased mine output to the current rate of 3.4 Mtpa of ore. The pre-expansion requirements were annual development of approximately 10 000 m and the placement of around 500 000 m 3 /yr of cemented backfill. Previous to 1995 all hoisting was carried out by the Whenan shaft. The Robinson shaft was commissioned during that year to hoist increasing development mullock tonnages and to allow for increased ore hoist via the Whenan system. In 1996 WMC committed to expanding the output of the operation from 85 000 tpa (1996/97 budget) copper metal to 200 000tpa. The corresponding increase in mine ore production requires expansion to a nominal rate of 9.0 Mtpa. To achieve these increased tonnages, major hardware installations will include sinking of a third shaft capable of hoisting in excess of 9.5 Mtpa, a rail haulage horizon utilising automatic trains, expansion of the existing backfill plant to a production capacity of over 1.8 million m 3 /yr, increasing long term development rates to 15 000 m/yr and increasing the production drilling and blasting rates in line with the higher stope production output. This paper provides detail into the intended hardware (shafts, equipment, etc) of the mining system, and outlines the intended long-term operation and management of the operation. Of particular note is the background requirement of ensuring existing production targets are met to provide critical cashflows into the project during the period of expansion.

Jan 1, 1998

By W Z. Liu, Q Q. Shi, H T. Yang, X L. Zhang

In order to improve the cutting blasting effect of dimension stone mining, the water coupling directional cutting blasting technology was put forward. Based on the test apparatus and special charge configuration, the mechanism of directional cutting blasting was analysed. Directional device changes the initial equilibrium of the total energy of shock wave effect on blasthole wall. The initial directional crack first appears in the blasthole wall that makes contact with the directional device. Then, two cracks are connected along the direction of the blasthole centre line under the action of detonation pressure and water wedge. The plexiglass tests showed that water coupling directional cutting blasting technology produced cracks along with the predetermined direction completely. The cutting surface was smooth and only a few short cracks appeared around the blastholes. It proved the validity of this technology.CITATION:Liu, W Z, Zhang, X L, Yang, H T and Shi, Q Q, 2015. Directional blasting rock cutting technology, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 815–818 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By G de Jong, W Sunyoto, M Cloos

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Ertsberg mining district is a 100 km2 area in the highlands of Papua, Indonesia. The district hosts mineralised and barren, outcropping and hidden porphyry and equigranular intrusions. There are at least six major (100+ m wide) porphyry intrusions identified from surface and underground mapping and drill cores. These are the Grasberg Igneous Complex (GIC), Karume porphyry, Lembah Tembaga porphyry, Ertsberg Stockwork Zone porphyry, Kay intrusion and the Wanagon intrusion. Recent deep drilling adjacent to the GIC identified a new hidden porphyry at depth, the Gajah Tidur (Sleeping Elephant), which extends south-west beneath the Kucing Liar skarn. Other named small porphyry dykes and plugs in the district include the West Grasberg, North Grasberg, Idenberg, South East and Zaagkam intrusions. The largest equigranular intrusion is the multiphase Ertsberg diorite.Igneous activities occurred in a relatively short span (<1 million years) from about 3.4 Ma to 2.7 Ma ago, based on U-Pb zircon dating. The various intrusions in the district related to ore mineralisation are high K and appear to have been derived from the same parental chamber, based on similar whole rock rare earth element patterns. Radiogenic Nd- and Sr-isotopic variations indicate that there were multiple recharge events into the parental chamber.The larger intrusions and all economic mineralisation occur in a 4 km wide zone that parallels the N60W-trending axis of the Yellow Valley Syncline (YVS), one of the large folds generated during collisional tectonism. Intrusion pathways at ~3 Ma were localised into dilatational areas in a late and/or post-collisional NW-trending, left-lateral strike-slip zone with Riedel shear offsets between the major fault zones. An early phase of lower K magmatism produced small intrusions in the south-west limb of the YVS.CITATION:de Jong, G, Sunyoto, W and Cloos, M, 2015. Composition, lithochemistry and radiogenic isotopes of porphyritic and equigranular intrusions in the Ertsberg mining district, Papua, Indonesia, in Proceedings PACRIM 2015 Congress, pp 347–356 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By J H. Park, M J. Lee

Because the environmental problems are occurred by greenhouse gases such as CO2, the industries have tried to increase electric motor efficiency to reduce CO2 emissions. A core material of electric motor is high-silicon electrical steel. The ferrosilicon (FeSi) alloy, a raw material for the production of electrical steel, affects the electric properties of silicon steel. The main impurities such as Ca, Al and Ti make inclusions or precipitates that causes core loss. The slag treatment has been widely used to remove impurity elements. Thermodynamic principles for the refining of several impurities, specifically Ca and Al, have been investigated, whereas thermodynamic behaviour of Ti has not been fully understood yet. Therefore, in the present study, the titanium distribution ratio () between ferrosilicon and CaO-SiO2-Al2O3 slag system at 1773 K was investigated. The results show that is influenced by both the basicity and stability of titanium ion in the slag. Specifically, exhibits a minimum value at about C/S=0.7 indicating a shift in the titanate structure unit from [TiO5]-square pyramid to [TiO4]-tetrahedron because of lack of Ca2+ ions in a C/S<0.8 region, contributing to an increase in titanate capacity and .

Jun 19, 2024

By Lee H. G, El-Rahaiby S. K

The literature relating to reduction of sulphides by carbon using lime as sulphur-absorbent is reviewed. A stage-wise thermodynamic model is employed to evaluate the practical feasibility of the direct reduction smelting of galena (PbS) concentrates with a carbon reductant in the presence of lime; a coke-rate of 65 kg/ton Pb is predicted by the model. The experimental data on the reduction of PbS:4CaO:4C mixtures under nitrogen were correlated by means of a finite difference numerical method and the values of the intrinsic rate constant I1 were derived. The results for the uncatalysed reduction are represented satisfactorily with log I1 = 1.247(&#177;0.522) - 5540(&#177;610)T-1.The catalysed PbS:4CaO:4C mixtures contained 2.5 wt% of ternary (K, Li, Na)2CO3 catalyst. For the catalysed reduction it was found that log I1 = 3.981 (&#177;0.301) -7790(&#177;353)T-1, where I1 (in both relations) is expressed in moles.(g.C.)-1.atm-1.s -I. The catalytic enhancement faclor was found to be quite large in the 1068 to 1262&#176;K temperature range investigated here.

Jan 1, 1991

By M Castello, P Bouchard, M Sabsabi, A Blouin, B Nguegang Kamwa, M Constantin, K Fytas, M Laflamme, K Rifai, F Vidal

Canada’s Quebec province operates 26 metal mines, 19 of which are producing gold and generating over C$1.8 billion (US$1.3 billion) annually. In all those mines, numerous samples of rock are collected and analysed daily in laboratories in order to determine their gold content. However, laboratory results are generally available within 48 hours of sampling (depending on the number of samples received by the laboratory and the priority of the results), thus potentially slowing down mining activities. In an attempt to find a solution for delayed laboratory results, Laval University, in partnership with the National Research Council Canada (NRC), the National Institute for Scientific Research (INRS) and four mining companies (Agnico Eagle, Canadian Malartic, Hecla Qu&#233;bec and Iamgold) have launched the Laser-Induced Breakdown Spectroscopy (LIBS) project for in situ real-time mining sample analysis. This work aims to minimise the amount of LIBS point sampling necessary to be representative of a full scan of the analysed area. Eight sampling patterns are investigated. A statistical analysis of the data was performed by varying the pattern steps. Results show that two of the patterns, 1 and 5 (single diagonal crossing the stratification of the samples with opposite slopes) minimise the amount of point sampling while remaining representative. The most successful results are obtained from steps which are greater than 6. In terms of the type of material, pattern 5 and steps 9 are better for core sampling, while pattern 1 and steps 8 are better for rock sampling. The geological explanation for these results is the heterogeneous distribution of gold in the sample which seems to be more homogeneous in the rocks than in the core sample due to the small rock size. In terms of the mineralisation, pattern 5 is better for mixed sulfides and quartz veins, and steps 8 and 9 are better for quartz veins.CITATION:Nguegang Kamwa, B, Rifai, K, Laflamme, M, Constantin, M, Castello, M, Vidal, F, Bouchard, P, Fytas, K, Blouin, A and Sabsabi, M, 2017. Sampling strategy by statistical analyses of LIBS data in the context of a portable gold analyser, in Proceedings Tenth International Mining Geology Conference 2017, pp 221–232 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By Golding D

The Charters Towers goldfield is located in the centre of a Lower to Mid-Palaeozoic igneous complex where schistose, amphibolite-grade metamorphic rocks were intruded by multiple phases of medium grained granodioritic rocks. Several generations of mafic and felsic dykes also occur. Two distinct mylonites cut all but the youngest granitoids. Gold mineralisation occurs in quartz veins located in brittley reactivated mylonite and in sympathetic fissures in the undeformed granitoids. The gold-quartz veins occur in complex, gouge-filled, 2.5m thick zones, with minor sulfides, surrounded by zoned phyllic and propylitic alteration assemblages. Four main vein systems are each restricted to separate granitoids or contain oreshoots near granitoid contacts. No genetic relationship between the granitoids and the vein systems can be documented. The early mylonitic fabrics and the granitoid contacts played an important role in ground preparation and in the localization of oreshoots. Non mylonitized granitoids also served as favourable hosts for many of the lodes. Whole rock values of 180 of the granitoids range between 6.5 and 7.9 per mil. Hydrothermal vein quartzes have 180 values between 12.2 and 15.7 per mil. Mylonite quartzes have values of 8.4 per mil. Variation in 180 values of quartzes is in part related to granitoid host rock type.

Jan 1, 1987

By A Suwandhi, H Utama

PT. Indo Muro Kencana (PT.IMK) is a gold mine that is located in Central Kalimantan, Indonesia. Drilling and blasting activity is applied in order to support mining production. Drilling and Blasting (D&B) planning is conducted by its engineers. A drilling and blasting contractor conducts drilling and blasting activity. The objective of this paper is to evaluate the implementation of the scaled depth of burial (Chiappetta and Treleven, 1997) in explosive charging sheet application to increase blast efficiency. The function of the scaled depth of burial is to maintain stemming height above explosive charge in order to prevent the ‘over energy’ condition, to reduce the excessive fly rock possibility, to maintain rock fragmentation (digger’s productivity) and to increase blast efficiency. The focus of this paper is to implement the scaled depth of burial as a reference in D&B planning and practice, especially in designing stemming height. The purpose of this paper is to validate that the scaled depth of burial can be used as an engineering tool in D&B practice in PT.IMK. However, scaled depth of burial cannot applied as an engineering tool to determine stemming height above explosive charge for trim blastholes and secondary blasting area. In general, the implementation of the scaled depth of burial in PT.IMK is applicable for production blastholes (ore and waste blasting). In conclusion, it is clear that scaled depth of burial can be used as an engineering tool to create explosive charging sheet and also to increase blast efficiency (ore and waste blasting) in PT.IMK.

Jun 22, 2022

Models of the genesis of existing ore oodles and targetting of exploration for new mines are greatly enhanced by an-understanding of the plate tectonic environment existing at the time of mineral emplacement. In areas of recent or active tectonism, a study of the present-day crustal and upper mantle structure is an obvious starting point in unravelling the evolution of the accessible upper crust. Bougainville is the northern-most island in the Solomon Islands arc. A 7km deep trench almost 100km off its western coast marks the commencement of subduction of the Solomon Sea plate beneath the Pacific plate. As outlined by the seismicity, the subducted crustal slab under the southern half of Bougainville reaches the axis of the island at about 100km depth, from which point it dips near vertically another 300km into the upper mantle. Large surface blasts at the Bougainville Copper Mine at Panguna, Bougainville, Papua New Guinea were used to derive an unreversed upper crustal profile of the island. The crust appears to be relatively simple, being comprised of a 5km deep layer with a P-wave velocity of 4.5km/sec, overlying a l0km thick layer with a P-wave velocity of 7.2km/sec. Constraints on the 15km mantle depth were provided by the identification of both P to and S to P phase conversions of seismic waves from local shallow earthquakes at the Moho boundary. An upper mantle velocity of 7.95(¦ 0.15) km/sec was measured from travel times of selected shallow earthquakes along the strike of the island arc.

Jan 1, 1987

By D P. Obeng, L Reemeyer, R Holmes

The Zinifex Century Mine employs a large number of Detritor mills for fine and ultra-fine grinding to liberate silica and sphalerite at 80 per cent passing 7.5 microns before final zinc flotation. A joint project between CSIRO Minerals and the Zinifex Century Mine was carried out to evaluate the Detritor mill performance. Plant surveys were conducted around the Detritors in conjunction with laboratory tests. The survey data showed that the Detritors in the ultra-fine milling circuit performed well. They reduced a feed F80 sizing of 46 microns to a product P80 sizing of 7.5 microns at a gross energy consumption of 37.2 kWh/t. Scale-up of ultra-fine milling Detritors was studied using a 0.55 kW laboratory batch unit and a 355 kW full-scale Detritor by processing Century zinc concentrate with 1 mm sand media. The results indicated that the 0.55 kW laboratory mill underestimated the energy consumption of the full-scale Detritor by about 20 per cent for a product P80 of seven microns. The performances of a horizontal IsaMill and a vertical Detritor were compared as ultra-fine milling devices for processing Century zinc concentrate. The experimental data demonstrated that, when using the same grinding media, the energy efficiency of the two mills is similar despite the difference in mill designs. The Detritors used for regrind duty at the Century Mine performed poorly when processing feed at 80 per cent passing 88 micron. The energy consumption was high and the product size distribution was broad with particles above 100 microns in the feed unbroken and particles below ten microns overground. A coarser ceramic media of 3 mm was therefore tested in a laboratory Detritor to process the regrind Detritor feed as an alternative to the 1 mm Colorado sand used at the Century Mine. The ceramic media reduced the energy consumption significantly and produced a narrower product size distribution, which is more desirable for the downstream flotation process.

Jan 1, 2007

By J J. Frausto, G R. Ballantyne, M S. Powell, R Cruz, K Runge

Hydrocyclones are the most widely used device for classification in a grinding circuit. However, even the most efficient hydrocyclone has a bypass of fines from the feed to the underflow which reduces comminution circuit performance, as well as misclassification around the cut point. Fine screens classify only according to the particle size, allowing for a reduction in the recirculation of fines back to the mill. The development of high capacity multi-screens makes fine classification in a grinding circuit a viable option. Minera Saucito recently substituted hydrocyclones with screens in its grinding circuit. The change of classifier resulted in an increase in throughput and lead recovery but a decrease in silver recovery. This case study presents the changes in comminution and flotation performance that occurred after the installation of screens and uses historical operational data collected over 12 months of operation to investigate the reasons for these observed changes. CITATION:Frausto, J J, Ballantyne, G R, Runge, K, Powell, M S and Cruz, R, 2017., in Proceedings MetPlant 2017, pp 298–314 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By L Smith, R Beckie

An intermediate scale (8 m + 8 m + 5 m high) constructed waste rock pile experiment was built upon a contiguous grid of 16 gravity drainage lysimeters to investigate the flow of water in unsaturated waste rock. Average net infiltration to the uncovered waste rock pile is 55 per cent of precipitation. Large rainfall events have net infiltration of 55 per cent to 85 per cent. Net infiltration estimates range from 23 to 120 per cent of precipitation between lysimeters. Small-scale lysimeters of less than 4 m2 area are shown to be poor predictors of net infiltration for uncovered waste rock. The appropriate size for lysimeters increases with increasing flow rate. The residence time distribution has an estimated median value of 3.0 to 3.9 years under average infiltration conditions. Water flows within the fine grained matrix, within larger pores (macropores), and in matrix free areas of the pile. In situ tracer concentrations vary between pore sizes, and between spatially distinct areas of the pile, indicating water geochemistry may also be variable. Water samples collected from in situ soil water samplers are dominated by the most mobile water fractions. In situ measurements of water content and matric suction are compared to the measured outflow. The data indicate the focusing of flow in spatially distinct areas can make in situ instrumentation a poor (non-conservative) predictor of volumetric water flow.

Jan 1, 2003

Experimentally determined and theoretically explained phenomenon of zonal disintegration of rock around the development working brings about the radical changes in existing ideas about the mechanism of interaction rock massive with engineering constructions.The essence of the phenomenon consists in the fact, that forming of non-elastic deformations zone goes on by way of more intensive deformation and destruction of rock simultaneously in several zones, covering partially or fully output circuit and divided by zones of destructed rock. Under the influence of change of massive strained-deformational condition of depositional rock an accidental deviation of zones of supplementary expansion and compression of rock from the previous positions take place. One can observe multiplicational change of the outline, size and form of all disintegration zones in the time within the area of the working influence at massive. This phenomenon was named "fluctuation of zonal disintegration of sedimentary rock around development working".

Jan 1, 1991

By W G. Rowley

The Fortescue Metals Group story began in 2003 with a vision to establish an infrastructure project that would connect the stranded iron ore deposits of the Pilbara region of Western Australia with the steel mills of Asia. Following exploration successes in the Chichester Ranges using their new exploration model, Fortescue established significant iron ore resources at Cloudbreak and Christmas Creek during 2004 and 2005. By May 2006 the definitive feasibility study for mine, rail and port was completed, many of the key government approvals had been obtained, product development and market acceptance were complete and 1.07 Bt of total proved plus probable iron ore reserves were defined to support a 20 year mine life from the Cloudbreak and Christmas Creek deposits. Project construction commenced in September 2006 following a successful $3.2 billion capital raising. By April 2008, the mine and processing plant at Cloudbreak were completed along with the Herb Elliott port facility at Port Hedland and 256 km of heavy haul railroad linking the mine with the port. Mining of overburden commenced at Cloudbreak in late 2007 and by 15 May 2008 the first shipment of iron ore had departed for China. In the first 12 months of operation total shipments amounted to 24.6 M wet metric tonnes with weighted mean composition of 58.9 per cent Fe (64.4 per cent Fe calcined), 4.3 per cent SiO2, 2.0 per cent Al2O3 and 0.047 per cent P. Exactly 3.5 years between the Cloudbreak discovery hole and commercial production. The project success depended on many technical breakthroughs including a new exploration model, application of the surface miner as the main mining production unit, design of a new marketable fines product called æRocket FinesÆ, a highly efficient ædesandÆ flow sheet for upgrading of 2.4 per cent alumina run-of-mine to 1.9 per cent alumina Rocket Fines, 40 t axle loads for the heavy haul railway and a high capacity-highly automated port facility.

Jan 1, 2009

When it comes to structuring major mining contracts, the two most widely adopted formats are æmeasure and valueÆ and æcost-plusÆ. A problem with both of these formats is the difficultly of aligning the objectives of the mining company with those of the contractor to achieve mutually beneficial outcomes. An alternative contractual arrangement is for the mining company to enter into an Alliance arrangement with the contractor, linking remuneration to mine performance across a range of targets. These targets can change over time as operational requirements change. &nbsp; The aims of this paper are to: +&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; outline alternative types of mining contracts, as well as their strengths and pitfalls; +&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; describe the philosophy behind the Alliance contract at Newmont Waihi GoldÆs Favona underground mine; and +&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; identify some of the keys to success and pitfalls to avoid when implementing an Alliance.

Jan 1, 2007