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By R G. Barker

This paper reviews the annual status of the New Zealand mining industry (metallic minerals and coal) including key aspects such as mineral production, mineral exploration expenditure, commodity price trends, key industry players, market activity and other significant commercial factors.   Strong commodity prices during 2006 have been underpinned by a number of key factors including US dollar weakness and emerging market demand, particularly from countries such as China and India. In real terms commodity prices have recovered significantly since 2002 and are currently at 20-year highs.   New Zealand exploration spending on metallic minerals (predominantly gold) is at a 15 year high driven by rising global commodity prices. New Zealand gold production in 2006 was about 340,000 oz and is expected to grow in 2007 as new mines at Frasers and Globe-Progress (Oceania Gold) and Favona (Newmont) come on stream. Gold production broadly lags 10 years behind exploration spending and exploration activity over the last five years remains well below that seen in the early 1980Æs. Expenditure on coal exploration shows a similar trend with strong growth from a low base over the last five years, reaching over $11 M in 2006. Total coal production in 2006 was 5.9 Mt, an increase of 10% on 2005 with imports from Indonesia adding a further $1.1 Mt.   Newmont and Oceana Gold are by far the largest public gold mining companies operating in New Zealand, although only Oceana Gold maintains a presence on the local stock exchange. Other metals explorers with New Zealand projects include a range of public-listed Juniors (market capitalisation less than NZ$50m) domiciled largely in New Zealand, Australia and/or Canada. Capital-raising on public markets directed towards New Zealand exploration is estimated at around NZ$12 M for 2006, the bulk of this coming via Glass EarthÆs NZ$10 M IPO on the NZAX in October.   The New Zealand Coal sector is dominated by the state-owned enterprise Solid Energy with around 80% market share by production. Other domestic coal competition remains limited, and includes the L&M Group, Pike River Coal, Eastern Corporation, and New Vale (acquired by Solid Energy in 2007). Pricing parity comes mainly from imported coal and global thermal coal prices have remained strong during 2006 at around US$45-55/t, driven by continued expansion in Chinese demand. Coking coal prices have eased 16% since 2005 to around US$98/t in 2007.   Although recent increases in exploration spending suggest a renaissance in the New Zealand minerals sector, long-run trends indicate that we have simply rebounded from a low base over the last five years and much work is still to be done to stimulate further growth in the mining industry to maintain minerals production at current levels. Key industry challenges include marketing exploration opportunities to local and overseas investors, building a critical mass of NZX-listed explorers and providing an internationally competitive environment to attract further capital and expertise.

Jan 1, 2007

By Benjamin H. Clark

"For over 50 years, Derrick Corporation has been renowned for its innovative and durable fine screening equipment and screen surface technology. Derrick’s latest innovation, the patented Stack Sizer, offers mineral processors both high tonnage capacity and high separation efficiency on an extremely small footprint.The Stack Sizer is suitable for separations from 6.3 mm down to 75 microns (200 mesh). The Stack Sizer, coupled with Derrick’s patented urethane screen surface technology, offers an extremely economical alternative to hydraulic classifiers, hydrocyclones, and less efficient low volume wet screening systems. Stack Sizers have been used in feed preparation for flotation, spirals, and a variety of jigs. Mineral processors wishing to reduce grinding circuit circulating loads and generation of slimes due to over grinding, thereby enhancing the efficiency of flotation and gravity circuits, now have another technology at their disposal to perform this critical sizing and grade control function.Over 200 Stack Sizers have been installed in numerous mineral processing applications worldwide attesting to the rapid acceptance of this technology. Stack Sizers are currently screening ferrous and non-ferrous metal ores, mineral sands, silica sand, kaolin clay, feldspar, garnet, phosphate, aluminum dross, potash, coal, tantalum, spodumene, niobium, and other rare earth mineral ores.INTRODUCTIONDerrick engineers have long understood and demonstrated the importance of screen width in coupling both high capacity and high separation efficiency for fine wet sizing applications. As opposed to fine dry sizing, where the length of the screening machine is critical for high separation efficiency, introducing slurry feed to screens in a thin and even layer at minimal velocities across wider screen surfaces allows for high capacities and efficiencies, with maximum screen cloth life. This is due primarily to the combination of free liquid and high frequency vibration of the Derrick motors, which allow fine undersize material to pass through the screen apertures. Lacking either of these factors would be extremely detrimental to the screening process. Without the high frequency vibration of the motor, the screen is essentially a low efficiency sieve bend. Without the free liquid to carry fines through the screen openings, the screen is for all intents and purposes a glorified conveyor or dewatering unit, as little or no sizing takes place once the screen is devoid of free liquid. For optimal screening results, Derrick recommends feeding slurry to a screen at approximately 20% solids by volume. Figure 1 shows the Stack Sizer design concept. Note that a single feed point is used to evenly distribute the flow to the five separate feed points."

Jan 1, 2007

By Steve Dubnewych, Jon Kaneshiro, Calvin Jin

The Joint Water Pollution Control Plant (JWPCP), operated by the Sanitation Districts of Los Angeles County (the Districts), treats wastewater generated by over3 million people and processes wastewater solids generated by over 5 million people. The JWPCP Tunnel and Ocean Outfall Project, if constructed, would be one of the major marine outfall projects in the world. The new tunnel and ocean outfall system would provide relief to the existing outfall and allow inspection, maintenance, and repair of the existing tunnel and outfall system, portions of which were constructed as early as the 1930s. Geologic conditions are challenging along the alignments within the study are a being considered. Conditions include saturated alluvial soils, weak sedimentary rock, mixed face conditions, and squeezing ground conditions. Other significant challenges include the potentials for encountering up to 11 bars of water pressure, crossing seismically active faults, and encountering gassy and contaminated ground conditions. This paper discusses the details of the proposed project and the associated challenges.

Jan 1, 2007

By Hamid Maleki

In this paper, the authors present a review of data gathering programs and stress analyses for improving mine layout designs at BRL mines located near Paonia, Colorado. BRL and other companies have used both longwall and continuous miner methods for the extraction of the Upper D, Upper B, Lower B and C seams from the multiple-seam reserves in the North Fork Valley. Historic mining in the B and C seams has created stress footprints in the neighboring unmined seams compounded by stress transfer from recent longwall extraction in the Upper D Seam. Thus optimum positioning of workings in the remaining reserves requires careful collection of pertinent data and consideration of load transfer from previous workings through remnant abutment pillars. Based on long-term subsidence monitoring, underground mapping and stress analyses, we have confirmed initial load transfer analyses finding mild interactions between the UD and LB workings, and the mining conditions have proven to be good and manageable during the development stage of the LB Seam. This has been achieved through prudent mine planning, prudent positioning of the gateroads in multiple seam workings and support allocations.

Jan 1, 2007

By John F. Gamble

Paper 1?South African experience with asbestos-related environmental mesothelioma: Is fiber type important? Neil White, Gill Nelson, Jill Murray The purpose of this review was to illustrate the importance of the type of asbestos in environmental mesothelioma. South Africa is a logical place to assess fiber type. The three major types of asbestos (crocidolite, amosite and chrysotile) were mined (all asbestos mining stopped in 2002) in South Africa. The association between asbestos and mesothelioma was discovered in South Africa. The occupational literature indicates high mesotheliomagenic potential for crocidolite, less for amosite and less still for chrysotile. Since South Africa has been a major source of crocidolite, relatively high rates of mesothelioma in the mining population is not surprising. High rates of mesothelioma due to environmental exposure is surprising, except perhaps when the authors? point out potential sources for community exposures (e.g., mine tailings used for road surfacing, golf courses, brick and plaster making; insulation in residential ceilings; children playing on fiber-rich waste rock). The authors? reviewed four studies reporting on mesothelioma cases and their sources of exposure and fiber type. Overall 23% of the known cases were attributed to the environmental (not occupational) exposure and about 90% were due to crocidolite asbestos. The proportion of environmental mesothelioma is considerably higher than in Western Australia where crocidolite is also mined. There the overall rate of environmental mesothelioma is about 6% (and less than 1% from residence in a crocidolite mining area).

Jan 1, 2007

This article focuses on TurkeyÆs gold potential with respect to exploration, development and operation after 1985. Apart from TurkeyÆs geology, which offers a substantial number of volcanic-associated gold (Ag) and gold-copper (Au-Cu) projects, there are numerous other factors which make the country a favourable place for mining. Turkey has a mining history which goes back to pre-Roman times and an excellent mining code which ensures security for long-term production. In the country, the Government and local villagers are very positive and the country works extremely well logistically with excellent road and telecommunication links. The opportunities for new discoveries in Turkey are very high. Moreover, Turkey has its eyes turned west as it moves towards joining the European Community and it is no surprise that international companies believe it has got its timing as well as its partner relationship right. Newmont, Teck Cominco, BHP Billiton, Rio Tinto, Eldorado Gold, etc all have direct or indirect interests in Turkey, as do an increasing number of midtier and junior exploration companies. Turkish Koza Gold Mining is the first Au producing company of Turkey. The Eldorado Gold owned 245 t Kisladag Au deposit in Western Turkey is currently also producing Au. In the meantime Anatolia Minerals Development is advancing the 131 t resource at the C÷pler Au deposit in North Eastern Turkey. These are significant world-class deposits. Further encouragement for investment in the Au mining sector has been provided by the introduction of a new mining law in 1985. Foreign investments in the country were encouraged and have seen a rapid increase in the last two decades. Gross domestic product (GDP) growth is in excess of five per cent per annum, inflation is down from 70 per cent to single figures, the budget deficit has been cut by 40 per cent to 11 per cent and industrial output and productivity are increasing rapidly. Turkey is politically and economically stable, is a member of the European Customs Union, has a supportive mining legislation, is highly prospective and under-explored and hosts significant recent gold discoveries.

Jan 1, 2007

By L Reynolds

Oceana Gold (New Zealand) Limited (OceanaGold) has commenced mining operations at the Globe-Progress mine in the Reefton Goldfield, an area that historically produced 2.1 million ounces of gold from underground quartz lode deposits. During the construction phase of the operation, advanced exploration programmes targeting near-mine prospects commenced. The focus of this ongoing exploration is the discovery of near surface, refractory gold deposits that are amenable to open-pit mining methods and treatment through the Globe-Progress process plant.   One such discovery is the Supreme deposit, located along strike approximately 3 kilometres to the south of the Globe-Progress mine. The Supreme area was tested extensively with diamond drilling in 2006, defining a deposit with similar mineralisation styles and grade to the Globe-Progress deposit. The mineralisation comprises a central core of gold-bearing quartz veins, locally containing visible gold, surrounded by a more extensive halo of refractory, disseminated gold associated with an arsenopyrite-pyrite sulphide mineral assemblage. Three subparallel mineralised structures host the mineralisation. These structures are highly oblique to the country rock orientations, extending approximately 250 metres along a northeast-southwest strike and at least 220 metres down-dip, with an average thickness of 12 metres and moderate dip to the southeast. Records of historical workings indicate that mineralisation extends further down-dip and remains open at depth. 5175 ounces of gold were mined historically at the Supreme deposit. OceanaGold have defined an Inferred Resource for the Supreme deposit of 0.84 million tonnes at 1.46 grams per tonne for a total of 40 000 ounces (at a 0.8 grams per tonne cut-off). Higher-grade zones of mineralisation exist within the deposit and further drilling is planned to test the extent, continuity and geological controls of the mineralised structures.

Jan 1, 2007

By Zephaniah Varley, Dominic Parmantier, Paul Schmall, Richard Martin, Red Robinson

Sequential excavation of the Beacon Hill Station has been accomplished in highly complex and inter-layered sand, silt, and clay soils with multiple perched groundwater tables. Successful excavation has required the installation of a deep dewatering well system used to depressurize sand layers above and within the excavated tunnel faces. In addition, the presence of sand layers in the crown of the Platform Tunnels required jet grouting at depths of up to 49m (160-ft). This paper discusses the design intent, construction, and effectiveness of the dewatering system and the selective jet grouting of sand horizons and shaft break outs for the successful construction of the deepest SEM station excavation ever completed in the United States.

Jan 1, 2007

By D C. McPhail, S L. Rogers, J Brugger

Using iron- and sulfur-oxidising bacteria to catalyse the breakdown of sulfides that host the gold is an important biological method for the pretreatment of refractory gold ores. Following this biological treatment a combination of chemical and physical methods are used for leaching (such as the cyanide process) and concentration (such as carbon-in-pulp or electrowinning) of gold. Although these methods are well accepted by industry, they harbour limitations in the processing of low-grade refractory ores, and regulatory agency/public acceptance of cyanide use. Thus, it is beneficial to industry to develop environmentally friendly, cost-efficient leaching and concentration techniques that are based on micro-organisms. This may soon be possible by adapting the results of recent regolith geoscience research, which has shown that micro- organisms are capable of driving a biogeochemical cycle of gold dispersion, transport and reconcentration in the supergene environment. The indigenous microbiota in biologically active soil microcosms from a number of Australian sites are capable of solubilising up to 80 wt per cent of the gold contained in these materials during 50 days of incubation. Studies using molecular microbial techniques have shown that a metallophilic bacterium, Ralstonia metallidurans, is present in biofilms on gold grains from a number of Australian sites. R metallidurans is capable of actively accumulating gold from solution, suggesting that the bacterium may contribute to the formation of secondary gold grains and nuggets. Identifying the biochemical and physiological pathways that lead to the dispersion and accumulation of gold in regolith, and quantifying the reaction kinetics of these processes may thus lead to the development of industrial bio-processing capacities for gold-containing ores.

Jan 1, 2007

By Gift Chisakuta, Bravo Mbao, Nils Schwarz, Angus Feather, Anthony Mukutuma

Bwana Mkubwa is a 50 000 tons per annum copper cathode producer, owned by First Quantum Minerals and located in Ndola, on the Zambian Copperbelt. The Bwana Mkubwa solvent-extraction circuit was started up in 1997. In 2002, the plant began treating ore from First Quantum?s Lonshi mine located in the Democratic Republic of Congo. The Lonshi ore is exceptionally fine and the amount of solids in the feed solution reporting to the solvent-extraction feed solution increased dramatically. Initially, crud was filtered in a filter press, but this rapidly blinded and seldom produced anything better than a wet sludge containing large quantities of organic. In December 2003 the decision was made to install a Flottweg Z4E-3/441 Tricanter® centrifuge to recover organic from the crud. The installation was completed in June 2004 and has since led to significant improvements in plant operability and savings in organic consumption.

Jan 1, 2007

By S Rupprech, T Lund, H Fourie, PH van Rooyen, NM Vegter

Rosh Pinah Zinc Corporation (Pty) Ltd (RPZC) operates an underground mine at Rosh Pinah in southern Namibia producing zinc and lead sulphide concentrates. It currently mines around 0.7 Mtpa run-of-mine ore containing around 6-10% zinc and 1.5-3.5% lead. As part of past exploration and current intensified exploration, a massive continuous low grade ore body was identified which grades at around 3% zinc equivalent. This ore body is near current mining infrastructure and could be amenable to bulk mining methods. In the present paper a concept is presented on how it could be exploited. As a precursor to exploitation of the low grade a number of enhancements are proposed for the current mining operations including: ? shortening load-and-haul distances by extending the conveyor raise further down the mine in a phased manner and back-filling of waste into mined-out stopes; ? use of mobile crushing plant at the crusher tip, and; ? installation of a system to allow scoops to load directly from stopes into ore passes close by combined with truck loops to haul from these ore passes to the crusher tip. To exploit the low grade ore body the following concepts are proposed: ? open stope mining from two areas at a total rate of up to 2 Mtpa; ? underground pre-beneficiation of mined low-grade ore near the stopes using either dense medium separation or X-ray sorting; ? pre-beneficiated tails back-filled to mined-out stopes and; ? pre-beneficiated product transported to surface by linking into proposed run-of-mine conveying system.

Jan 1, 2007

By F. Dahl, P. Raleigh, J. Holzhauser, B. Nilsen

Tunnel excavation using tunnel boring machines (TBMs), has become increasingly common in recent years, despite the fact that precise evaluation of certain risks have not kept pace with the use of these machines. One of the risks easily overlooked by Engineer and Contractor alike are the effects of abrasive ground on the costs and schedule of a given project. The impacts of worn and damaged TBM cutter heads have been observed on hundreds of tunnel projects around the world. It would appear that a reliable prognosis of the abrasiveness of soils on a project would be of great importance for designers, clients and contractors alike. Several well acknowledged test and prognosis methods already exist for rock, however there is only very limited knowledge available to describe the abrasiveness of soil and its impact on soft ground TBMs. This paper will examine approaches to this problem and suggest a new approach based on a current project undergoing design.

Jan 1, 2007

By William M. Gleason

When SME’s 2006 Arizona Conference convened in December at the Hilton El Conquistador Resort in Tucson, AZ, there was considerable excitement among the 387 attendees. There was a noticeable buzz surrounding the progress of Phelps Dodge’s Safford copper mine in southern Arizona, one of the first new major copper mines to be permitted in more than 30 years in the United States. There were also plenty of good feelings about the mining industry in general. Commodity prices remained high and with no signs of a slowdown in the immediate future. Things were good in Arizona. But there were also cautionary tones at the conference and the Mining Foundation of the Southwest banquet that preceded it.

Jan 1, 2007

By Helmut Hass, Michael B. Gilbert

The extension of the commuter railway system (S-Bahn) in Leipzig, Germany willrequire the construction of an underground line crossing the downtown area of thecity to tie the Bavarian Station in the South to the Main-Station in the North. The City-Tunnel-Leipzig is currently one of the largest infrastructure projects in Europe. This system extension will have a length of approximately five kilometers. 3.9 kilometers of that length are currently being constructed using either cut & cover construction or tunnelingmethods. The design and construction of this project currently is and will continue facing very significant challenging urban and demanding geotechnical conditions.

Jan 1, 2007

By J. J. Montoro

The influence of blasting on the excavators’ efficiency, defined as mucking rate (amount of rock mucked per unit time) and mean bucket load (amount of rock loaded in each bucket operation), is investigated. Rock characteristics, blasting parameters (drill pattern, explosive energy, and charging), and the excavator’s performance (truck loading time and number of buckets to fill a truck) were monitored in eleven blasts in an open pit iron ore mine. ANFO, ANFO/emulsion blend, and watergel were used in the blasts and the powder factor was varied between 0.98 and 1.45 kg/m3. The mean bucket load is mainly affected by the bucket size, which is independent of the blasting parameters. Besides the relation with the mean bucket load, the mucking rate was found to be positively correlated with the explosive energy, whereas no significant correlation with the rock properties was found. The analysis of the data, together with other published works, suggests a non-monotonic relation of the mucking rate with the powder factor, with a maximum mucking rate at a certain powder factor. This is especially true when the useful work of the explosive per unit rock volume is used rather than the classical mass powder factor and when only the amount of explosive above grade is considered.

Jan 1, 2007

By J. E. Nesset

The bubble size, together with the gas rate, determines the bubble surface area flux in flotation machines and, therefore, impacts directly on the kinetics of flotation. Understanding the variables that influence bubble size is one of the keys to understanding flotation recovery. Surprisingly, these relationships are poorly understood, largely due to the difficulties associated with gas dispersion measurements in industrial environments. The McGill gas dispersion sensors (bubble size, gas rate, gas holdup) are capable of reliably making such measurements. This paper reports on a study, using the McGill sensors in a 0.8 m3 Metso RCSTM pilot cell, which investigated the effect on bubble size of frother type and concentration, gas rate, temperature and rotor speed. A Denver laboratory cell was used to investigate the effect of elevation above sea level. Frother concentration proved to have the predominant influence on bubble size, and the effect of frother type can be normalised as a function of the critical coalescence concentration (CCC). Measurements made at many plant sites worldwide are compared to the model developed using the Metso RCSTM unit.

Jan 1, 2007

By R. P. Goel, P. N. Chaudhary, R. K. Minj

The bulk of high carbon ferromanganese produced in India continue to have more than 0.35% phosphorus since they are produced by carbothermic reduction process. The low phosphorus manganese ores are depleting fast and ferromanganese manufacturers will have no option but to use medium and low grade ores having high phosphorus content resulting in high phosphorus in the product. A systematic study was taken up at NML to solve this problem. Initially, a thermodynamic analysis was carried out for which Ba-P-O ternary predominance diagrams were constructed at several temperatures to predict the most suitable conditions for selective removal of phosphorus from high carbon ferromanganese. These conditions required a usage of a flux having a high level of basicity, moderate oxygen potential as well as low melting temperature. The experimental results showed that it was possible to remove phosphorus from high carbon liquid ferromanganese from 0.56%to 0.18% using BaCO3 based fluxes at the rate of 16-wt% of the ferromanganese charged. However, the Mn loss varied in the range of 2-5%. The objective of the subsequent study carried out at the laboratory scale was to optimize the flux consumption as well as minimize the Mn loss with effective dephosphorization by using BaO based calcined pellets instead of BaCO3 based powders. It was felt that the handling of pellets under plant conditions would be easier and also eliminate the loss of flux as a dust, which occurs when powder is added. These pellets were forced towards the bottom of the melt for better efficiency. For this purpose, a plunging system was designed and fabricated in-house that helped in reducing the flux consumption to less than 5% and also improved the kinetics of the process. The desired results were achieved within 10 minutes of the addition of the flux. The know-how is ready for transfer to interested parties and authors are willing to conduct large scale trials with them.

Jan 1, 2007

This paper presents the development of a regrind facility design at BHP Billiton's Leinster Nickel Operations (LNO) in Western Australia. The recovery opportunity was identified from an analysis of plant operating data together with scanning electron microscope (SEM) measurements on relevant tailings streams from LNO. A laboratory procedure was developed to determine the potential recovery improvement of installing a regrind facility at LNO. The last step in formulating the process flow sheet and defining the process design criteria was to construct and operate a pilot plant, which incorporated four banks of flotation cells and an Xstrata M20 Isa Mill. Pilot plant on/off trials were used to define the expected metallurgical benefit. A prefeasibility engineering design and cost estimate was completed. Following a successful internal business evaluation, a feasibility study is currently underway.

Jan 1, 2007

By Paul S. Fisk, Arne Fareth, Julie Frietas, Francis Lo, Fidel L. Mallonga

INTRODUCTION This report describes the inspection of parts of the New Croton Aqueduct (NCA)undertaken for the New York City Department of Environmental Protection (NYCDEP)by Parsons Brinckerhoff Quade & Douglas, Inc., (PB) in association with Montgomery Watson Engineers of New York, P.C. (MWH). Support for the inspection was provided by AFC Enterprises, Inc., under Construction Contract CRO-333, “WM-11 New Croton Aqueduct Rehabilitation and Inspection Program.” The scope of the inspection work under CRO-333 included assessing the condition of the 10.3 km (6.4 mile) long, pressurized section of NCA and inspection of shafts, head houses and blow-off structures in both the pressurized and gravity sections. The CRO-333 inspection continued investigation work begun under ContractCRO-196, which ran from 1993 to 1997. The CRO-333 inspections were conducted from November 2004 to September 2005. Background The New Croton Aqueduct was put into service in 1891 to deliver water from the Croton River Watershed in Westchester County to consumers in New York City. Figure 1 shows the location plan of Croton Water Supply System. The design flow into Jerome Park Reservoir was 12.7 m3/s (290 mgd) and into the135th Street Gate House, further south, was 10.9 m3/s (250 mgd). The NCA has been operated as a gravity conduit from Croton Lake to Gate House No. 1, just north of Jerome Park Reservoir, since its original construction. The length from Gate House No. 1to 135th Street, which includes a major siphon under the Harlem River, has been operated under pressure. Croton Lake gate house, the north end of the alignment lies at Station 4+75; Shaft 33, the south end of the alignment lies at Station 1628+05. The diameter of the tunnel is 3.2 m (10.5 ft) in the siphon and 3.7 m (12.3 ft) in the Bronx and Manhattan sections. The pressurized sections, constructed in rock, consist of a brick lining surrounded by a mortared and grouted rubble backing. Figure 2depicts a typical tunnel cross section. The objective of the shaft and tunnel inspections was to locate and document defects, such as leaks, deterioration of lining material, cracks, spalls, delaminations,

Jan 1, 2007

By C A. Fleming

Gold extraction is largely driven by mineralogical factors, which often cause gold losses to various tailings. Mineralogical factors affecting gold recovery include grain size and shape, surface coating or rimming on gold particles, the presence of cyanide or oxygen-consuming minerals or preg-robbers, the presence of slow-dissolving gold minerals and the refractory nature of submicroscopic gold. Among these factors, locking of fine gold particles in sulfide, silicate and other minerals, either as visible, fine-grained gold inclusions and/or as invisible submicroscopic gold, is by far the most common factor leading to poor gold recovery in gold ore processing. This paper discusses the mineralogical characterisation of gold lost in tailings and its metallurgical implications. The techniques used in characterising the un-recovered gold are also briefly introduced.

Jan 1, 2007