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By Gary J. Massoth

Wherever hydrothermal fluids vent from the seafloor they will buoyantly rise (up to 100?s of meters) while mixing with seawater before attaining density equilibrium and dispersing laterally as neutrally buoyant plumes commonly 50 to several 100?s of meters in thickness and with order-of-magnitude or greater breadth. Although these plumes are typically >10,000-fold dilutions of vent fluids they can be reliably detected using sophisticated physical sensing and chemical techniques. Hence, hydrothermal plumes are spatially large targets compared to the actual sites of seafloor fluid discharge and resulting mineralization. For this reason plume prospecting techniques evolved over the past 20+ years have been widely used to systematically explore over 10% of the 60,000-km-long system of mid-ocean ridge (MOR) spreading centers for hydrothermal activity. While plume detection and gradient mapping can be used to home in on venting sites, plume chemical signatures provide additional insight regarding the nature of the fluids being discharged on the seafloor. We have applied the systematic plume prospecting techniques developed on MORs to the volcanic frontal arc setting as part of the NZAPLUME (New Zealand American PLUme Mapping Expedition) surveys. NZAPLUME I in March 1999 marked the first systematic reconnaissance of any intra-oceanic arc for submarine hydrothermal activity. Seven of thirteen previously mapped volcanoes that comprise a 260-km-long section of the southern Kermadec arc northeast of New Zealand were confirmed to be hydrothermally active. On average, one hydrothermally active volcano was found along each 35 km of arc front, a rate comparable to slow- and intermediate-rate spreading MORs. During NZAPLUME II in May 2002, thirteen previously unknown volcanoes and 8 satellite cones were first swath mapped for bathymetric detail and then surveyed using plume prospecting techniques. Three active venting sites were discovered along this 580 km-long arc section, bringing the total to 10, or 39% of 26 volcanoes surveyed overall, still an appreciable frequency rate for venting sites compared to MORs. While only chemical results for NZAPLUME I are available, the arc plumes characterized so far are chemically diverse and rich compared to MOR plumes. This diversity and enrichment was most evident as ultra-high concentrations of CO2, sulfur gases (St = SO2 + H2S), and Fe within plumes over several volcanoes. We suggest the fluids discharging from the seafloor at these sites are volcanic fluids, i.e., hybrid fluids comprised of MOR-like hydrothermal fluids evolved from seawater-rock reaction and fluids exsolved from magma as acid volatiles and liquid brines.

Jan 1, 2002

By S. J. Dillingham

One of the primary goals of every blaster is to achieve the optimum blast design. Too much focus on efficient design, however, can cloud certain issues and exposures that must be addressed if the entire project is to be considered .successful.. Due to the known human response to blast effects and inherent dangers present in the use of explosives, the potential for the project being delayed or shutdown, or the blaster and associated company being named as a defendant in a lawsuit, is always a possibility. Therefore, the blast design and associated project bid must incorporate sound safety contingences and procedures that address those .what-if. Scenarios that may arise as a result of vibration, flyrock, public relations, and job-site personal safety.

Jan 1, 2002

By M E. Barley, A D. George, M Kneeshaw

Detailed pit and outcrop mapping of sedimentary rocks and their alteration is providing insights into fluvial processes that operated during deposition of the world-class Yandi channel iron deposit. Five prominent rock units are traceable along the strike of the Yandi deposit and permit correlation of open pits and mesas. These units are the Eastern Clay Horizon (ECH), granule-pebble conglomerate (GPC), Main Ore Zone (MOZ), Basal Denatured Zone (BDZ), and Basal Conglomerate (BCONG). The upper part of the deposit is characterised by a transition from spheroidal grains with well-defined rims and nuclei to larger, subangular grains with poorly developed rims. The distribution of rock types and sedimentary features such as lateral accretion surfaces, channel scours and fills, graded bedding, cross-bedding, reworked horizons, and slumped strata are common at Yandi and indicate deposition in a fluvial system. Bedding is well preserved despite modification of original grain shapes and textures and introduction of secondary silica and alumina in the upper part of the deposit. The high lithic and clay content of the GPC and ECH possibly reflect changes in source area or a hiatus in deposition of the Marillana Pisolite. The MOZ and the BDZ may be the same depositional unit with the latter recording alteration by groundwater and destruction of primary textures and other sedimentary features. The BCONG is a channel lag deposit reworked during deposition of the MOZ. This interpretation is supported by the dominance of basement-derived lithic clasts, the presence of BCONG clasts, the variable thickness of the unit along strike and the presence of BCONG clasts in the BDZ.

Jan 1, 2002

By G Hall

BHP BillitonÆs (BHPB) Yandi ore deposit is a channel iron deposit (CID) in the Pilbara district of WA. The ore is predominantly a goethite-hematite pisolite and overlays a clay at the base of the deposit. Knowledge of the location of the contact prior to mining is critical to maximise ore extraction and minimise contamination from and mining of the underlying clays which contain high levels of alumina. The contact between the iron ore and the clay is highly irregular. Traditionally the contact has been delineated by closely spaced drilling û this can be expensive and since each drill hole only provides a point sample measurement, irregularities in the contact surface can be missed. In September 2001, three high resolution geophysical techniques were trialled to see if they could be used to improve the efficiency and accuracy of ore delineation. The three techniques were resistivity imaging, ground penetrating radar and electromagnetic conductivity imaging. The resistivity data showed a favourable correlation with the available ground truth data from drilling. Using this ground truth data as a calibration, an interpretation of the depth to the base of the channel iron deposit (CID) ore was constructed for the areas surveyed. A significant attribute of the method is that the position of the base of the ore is imaged continuously along the lines that are surveyed rather than at discrete points. No continuous well defined ground penetrating radar (GPR) reflections were observed from the base of the CID ore. There did appear to be some correlation between the range of echo times that reflections were observed and the drill data, however the precision to which the range of echo times could be estimated was of the order of several metres and therefore not adequate to replace current procedures. The electromagnetic data showed good correlations with the existence of shallow clays but did not discriminate between variations in CID ore depth. This technique is therefore not suitable for mapping the base of the CID ore but may still be useful as a rapid tool for mapping the position of clay bands.

Jan 1, 2002

By Hideki Yarnarnoto

The simultaneous removal for NH4+ and PO43- in aqueous solution was carried out by using Ca type zeolite synthesized from coal fly ash. The effect of pH on the cation exchange capacity and adsorption properties of the obtained zeolite, the simultaneous removal of NH4' and ~04'. in various solutions and the mechanism of simultaneous removal were investigated respectivel? ,The Ca type zeolite used in this study can simultaneously remove NH4+ and PO43- In aqueous solution without releasing counter ion, and this method gives great advantage over the other ordinary removal methods.

Jan 1, 2002

By J. M. (Mac) Beggs

With New Zealand?s ratification of the United Nations Convention on the Law of the Sea in 1996, the government of the day increased work on developing an oceans strategy to help create a governance framework for the country?s extensive existing and potential maritime territories. This project took a new direction in 2001 with the establishment of an ad hoc committee of 6 Ministers, and their appointment of a Ministerial Advisory Committee (on which the senior author served) to consult with the public, identify widely held values and inform the development of a Vision for subsequent policy development. The current second stage of the policy development process involves a working group of officials from the relevant agencies completing a stock-take of existing laws and regulations to identify overlaps and gaps that should be addressed in the third and final stage. The public consultation process revealed, as might be expected, a wide range of perspectives but a solid consensus in favour of a coherent, and balanced, framework to enable the realization of economic benefits of ocean development so long as appropriate environmental standards (broadly expressed in terms of sustainability) are not compromised.

Jan 1, 2002

By Rasin Duzceer

In this paper, the results of pile load test on 24 piles from twelve sites are presented. The pile load tests were performed on 14 driven and 10 bored piles of varying diameters and lengths installed in different ground conditions in Turkey, Saudi Arabia and Kazakhstan. The purpose of this study is to evaluate and compare the axial capacity of the piles obtained using pile load test interpretation methods. Davisson, Brinch Hansen %80, Chin-Kondner, Shen-Niu, De-Beer, Housel, Mazurkiewicz, Fuller-Hoy, Brinch- Hansen (90%), Corps of Engineers, Butler Hoy and Tangent Intersection methods were used to determine the axial capacity of the piles. Static analysis using FHWA method was performed to predict the axial capacity of the piles. A statistical analysis was performed to compare and quantify the load test interpretation methods. The ratio of interpreted (Qi) to predicted (Qp) pile capacity was compared for each method. For each pile load test and for each interpretation method, the mean and coefficient of variation of (Qi)/ (Qp) were calculated. Among twelve methods investigated, the highest Qi/Qp value was obtained as 1.37 for Chin-Kondner method whereas the lowest Qi/Qp ratio of 0.70 was obtained from De Beer method.

Jan 1, 2002

By James J. Graham

Uravan, Ambrosia Lake, Gas Hills and South Texas are all historic names in US uranium. These mining areas supplied the uranium that brought the United States into the nuclear age during the 1960s, and fueled the birth of nuclear energy for peaceful uses — a promise of nearly limitless, clean energy for the world’s future. That promise still exists today, but it is hard to hear over the rhetoric of environmental activists and politicians. Nuclear power offers dependable electricity with limited environmental impact at stable prices. Nuclear power releases no greenhouse gases or particulate matter into the atmosphere. High level nuclear waste (HLW), although long lived, is readily controlled and compact. In the United States, generating 1 billion kWh of electricity with coal produces 47 kt (52,000 st) of solid waste (ash and sludge), compared to 3.6 t (4 st) of HLW produced by nuclear.

Jan 1, 2002

By Dinesh Goyal

Industrial fly ash from (electro static precipitator) was mixed with soil at different levels on v/v basis for raising of pulpwood tree species. In field trials conducted on degraded soils increase in the plant growth of Eucalyptus tereticornis, Acacia auriculiformis and Casuarina equisetifolia by 10 %, was observed during the initial six months after plantation at 18-24% (v/v) fly ash concentration which was at par with chemical fertilizer treatment. Level of As, Se and Mo in flyash was 6.2, 3.6 and 4.0 ppm respectively. The radioactivity analyses 40K, soil and 28 fly ash showed that the activity levels of gamma emitting radionuclides K, Ra, Ac were within the permissible limits and mixing of fly ash with soil at tested concentration would have no deleterious effects. Available Co, Cr, Ni and Cd in rhizospheric soils were below detection limit. Fly ash at 10-20 % level (v/v) was also found to be a good potting mix material in forestry nurseries in terms of improving biomass production by 20 %, when tested in nursery seedlings of Eucalyptus tereticornis. Nursery addition of fly ash in soil decreased soil dehydrogenase activity and the soil bacterial population was negatively affected. These results indicate that use of fly ash in forestry sector involving nursery and plantations as a soil amendment agent upto 10-20 % v/v is a gainful utilisation of fly ash.

Jan 1, 2002

By A. McGarr

The shear stress t that can be sustained by the rock mass in the environs of a mining-induced earthquake controls the near-fault peak ground velocity v of that event according to v=0.25(ß/G)t, where ß is the shear wave speed and G is the modulus of rigidity. To estimate t at mining depths, I review the results of four studies involving Witwatersrand tremors that relate to the bulk shear strength. The first and most general analysis uses the common assumptions that the seismogenic crust is pervasively faulted, has hydrostatic pore pressure before mining, and an extensional stress state that is close to failure. Mining operations reduce the pore pressure to zero within the mine and redistribute the stresses such that, in localized regions, the state of stress is again at the point of failure. Laboratory friction experiments can be used to estimate t in the zero-pore-pressure regime. Second, model calculations of states of stress in the vicinity of mining at about 3 km depth indicated the shear stress available to cause faulting near the centre of a distribution of induced earthquakes. Third, laboratory experiments combined with microscopic analyses of fault gouge from the rupture zone of a mining-induced event provided an estimate of the average shear stress acting on the fault to cause this earthquake at a depth of 2 km. Fourth, moment tensors determined for mining-induced earthquakes usually show substantial implosive components, from which it is straightforward to estimate t. These four different analyses yield estimates of t that fall in the range 30to 61 MPa which implies that near-fault particle velocities could be as high as about 1.5 m/s. To the extent that the causative fault ruptures previously intact rock, both t and v, in localized regions, could be several times higher than 61 MPa and 1.5 m/s.

Jan 1, 2002

By Andrzej Tejchman

A method of improvement of a subsoil under bored pile base by injection is presented. The method employs a special chamber attached to the reinforcement at the bottom of the drilled borehole. The chamber is made of semi-permeable textile bag. The injection entered under high pressure into the bag, causes prestressing of subsoil under the pile base. The results of load tests of piles improved in this manner have shown a substantial increase of their capacity together with simultaneous reduction of settlements. This technology has been implemented for four constructions such as trestle bridges in Gdynia and Warszawa and the bridges in Szczecin and Gdansk. The injection effects are shown based on the load test results.

Jan 1, 2002

Although cyclones have been around in their current form since the early-1890s, there have been some exciting new developments, which have extended their efficiency/operation. These developments have taken place with both dense medium and classification cyclones. The more noteworthy developments are:Inlet designInlet design is the determining factor in classification cyclone capacity and efficiency. The recently developed ribbon inlet with patented pressure bulge has not only resulted in unbelievable increases in capacity, but also in efficiency. Sharpness of separation corresponding to an alpha value of greater than four has been achieved! Secondary offtakeOne of the factors leading to reduced cyclone efficiency is the presence of coarse particles in the cyclone overflow. The secondary offtake has been developed specifically to scavenge these particles from the cyclone overflow with great success. Water injectorThe other major factor resulting in reduced cyclone efficiency is the presence of misplaced fine particles in the cyclone underflow. The water injector, which has been around for many years in various forms, can reduce this short circuit fraction by up to 50 per cent. 3-in-1 cycloneThe 3-in-1 cyclone combines the inlet design, secondary off take and water injector into a single unit resulting in the most efficient classification cyclone available in the market. The RejectorTMIron ore has a high yield to underflow and traditional dense medium cyclones have always been spigot constrained. The Rejector TM is an exciting new development whereby the spigot capacity has been increased substantially. The application of the Rejector TM will result in fewer/smaller cyclones being required for a given duty resulting in efficiency gains and reductions in both operating and maintenance costs.

Jan 1, 2002

By S. Rajendran

Gas Hydrates (Methane Hydrates) are solid, ice ? like substances composed of water and natural gas. They occur naturally in areas of the world where methane and water can combine at appropriate conditions of temperature and pressure and are found in the ocean bottom sediments and in some permafrost areas. Besides temperature and pressure, factors like bathymetry, sediment thickness, sedimentation rates, and total organic carbon content (TOC) also control gas hydrate formation in the sea. The stability of gas hydrates depends on the critical high pressure ? low temperature combination (0 - 17 bars, 0 - 25°C), which in turn dependent on the mix of gases from which the mineral is formed. As the critical parameters can be altered by deposition, erosion or slumping of sediments, formation or melting of ice cover, rise and fall of sea level and sudden temperature changes induced by tectonic activities, current flows or volcanisms, the gas hydrates tend to be very unstable. The Indian offshore is promising with the occurrence of gas hydrates in a total of about 80,000 km2 area in the bathymetry range of 700 to 3000 m as reported in the earlier surveys. A gas hydrate stability zone thickness map was prepared using bathymetry and sea bottom temperatures along the continental margins of India. This map is expected to provide the depth window while searching for the ?Bottom Simulating Reflectors? (BSR). The study indicates that a minimum water depth of 750 m is required for the formation of gas hydrates, and above which the chances for gas hydrates occurrences appear minimal despite other favourable conditions like presence of sediment rich organic content etc. Single channel seismic analog records (Gupta et al., 1998) suggests that Western Continental Margin of India (WCMI) offers greater promise with to gas hydrate occurrences, particularly with regard to the number of BSRs traced on the analog records as compared to the earlier surveys.

Jan 1, 2002

By Ross W. Smith, Xiapeng Zheng, Peggy J. Arps

The adhesion (and de-adhesion) of Bacillus subtilis to dolomite was determined under a number of conditions of initial concentration of the organism, agitation, mineral particle size and temperature. Rate equations curves for both adhesion and de-adhesion were constructed, with the rates of de-adhesion being about half that of adhesion. From the temperature data the energy of adhesion was determined to be about 1.02 kcal/mol. Adhesion of dolomite to B. subtilis follows a Langmuir isotherm. Equilibrium constants, adhesion capacity and Gibbs free energy of adhesion of B. subtilis to dolomite (at pH 6.6) were determined. These values were compared to similar data for adhesion of B. subtilis to apatite and dolomite.

Jan 1, 2002

By H. Senoh

For the purpose of clarifying the reason caused a drastic decrease of discharge capacity for MmNi3.6Mn0.4Al0.3Co0.7 electrode at relatively low temperatures, various factors influencing the charge-discharge processes were investigated in the temperature range of 25°C to -40°C. The charge efficiency obviously decreased at low temperatures less than 0°C due to a decrease in the rate of the charge-transfer reaction on the electrode surface. Moreover, both the rate of the hydrogen diffusion from the alloy bulk to surface and the rate of the charge-transfer reaction significantly influenced the high-rate dischargeability. The addition of Mo to MmNi3.6Mn0.4Al0.3Co0.7 alloy was found to be effective for improving the electrocatalytic activity, leading to the improvements of the charge efficiency and the high-rate dischargeability at relatively low temperatures.

Jan 1, 2002

By Yves Breau, François Robichaud, Jacques McMullen, Pierre Pelletie

"The Expert System implemented at the East-Malartic mill controls a copper flotation circuit while taking into account the profitability of the operation. Treating a copper gold ore, the flow sheet integrates a flotation step followed by cyanide leach circuit. The Expert System calculates the actual net smelter revenue of the flotation circuit, accounts for the operating cost of the cyanidation circuit and defines optimal metallurgical operating targets to optimize the overall economics. To be realistic, probability factors and circuit diagnostic analysis are integrated in the operating target selection. The Expert System has proved to be successful, robust and flexible. It resulted in a copper concentrate grade increase of 1% while maintaining recovery. The use of the expert system also gives plant personnel good training procedures and promotes interaction with mill operator.INTRODUCTIONThe East-Malartic mill is located close to the town of Malartic in North Western Quebec, Canada. The mill was first commissioned in 1938. The flowsheet at that time was a straight cyanidation circuit. The original mill operated in that mode up to the discovery of the Bousquet 2 orebody in 1989 which consisted of a massive copper sulphide ore averaging 0.7% copper and 7 g/mt of gold. Bousquet 2 ore processing required a mill retrofit. Grinding capacity, gravity and copper flotation circuits were inserted prior to the cyanidation circuit in order to achieve 3,200 mtpd capacity at expected recoveries.In 1993, control of the flotation circuit was deemed critical in order to maintain the flotation performance and to reduce cyanide consumption since the copper sulphide contained in the Bousquet 2 ore is a high cyanide consumer (50% bornite). (McMullen, 1999) As a result, the implementation of advanced control strategies in order to increase the metallurgical profitability of the plant and to reduce the operating variability between operators was the most rational alternative. In 1994, Corem was chosen to perform the plant audit and to write the first set of rules. The on-line control strategy was started up in 1995. In 1996 and 1997 the Expert System was shutdown because of an extreme change in the ore coming from the milling of Bousquet #1 ore and the departure of the projects engineer. In 1998, the system was restarted and the results were impressive. Furthermore in May of 2001 a patent was issued for the control strategy. (Breau, 2001)"

Jan 1, 2002

By C. Garcia, H. Arias, J. D. Miller, C. L. Lin

The question of ultimate recovery in heap leaching operations is always of particular concern with respect to economic considerations. Of course the particle size distribution is a critical factor which determines ultimate recovery and which must be established based on a balance between the extent of mineral exposure and transport phenomena. Now it seems that the ultimate recovery for a given particle size distribution can be established from mineral exposure analysis by x-ray microtomography (XMT). Using recently developed software, micro-CT data can be used to determine the fraction of mineral exposed and thus the ultimate recovery. Examples of mineral exposure analysis are given for the copper heap leaching operation at Zaldivar, Chile.

Jan 1, 2002

By R. Parada

In January 1995, Disputada Mining Company Ltd. (Compañia Minera Disputada de Las Condes) started up the Expansion Project for the Chagres Smelter, following an investment of US$M 2 15. The new smelter replaced the 44,000 tomes per year revervatory furnace with an Outokumpu Flash Smelting Furnace (FSF) designed to produce 118,000 tonnes per year of copper. Nowadays, this smelting unit has achieved a 40% over design performance. The landmarks of this modernization project are described. The start up period in 1995-1996 was characterized by the impacts of several restrictions that prevented the smelter from reach design production. The design performance was reached in 1997-1998 through the implementation of solutions designed to eliminate, or at least mitigate, the restrictions found early on. The smelter has been further optimized in the 1999-2000 period, leading to a new record anode copper production rate of 148,000 tonnes in 2000 while obtaining 98% approval for our different anode shapes. The objective of this paper is to discuss the consecutive processes of start-up, achievement of design capacity, and operational improvements to go well beyond the design capacity. These processes took place between early 1995 and late 2000, under the principles of Continuous Improvement that promotes the effective participation of the workers in the technology innovation and Enterprise Management.

Jan 1, 2002

By R G. Barker, N Mortimer

In New Zealand, platinum group metals (PGM) occur in three main geological environments of economic interest: layered mafic igneous complexes, the Dun Mountain Ophiolite Belt, and in association with placer gold deposits. Most of the layered mafic complexes with PGM potential occur in the Median Batholith. These include the Longwood (Permian), Bluff (Permian), Riwaka (Devonian) and Rotoroa (Jurassic) igneous complexes. Exploration of the Longwood Complex discovered PGM associated with gabbroic rocks. Best assays to date include a 1 m drill intersection of 1 g/t Pt + Pd and float rock with 3.0 ppm Pt and 3.3 ppm Pd. The Greenhills complex at Bluff consists of basal dunite overlain by wehrlite and gabbro. PGM occur with chrome spinel in the basal dunite and Pt geochemical anomalies have been identified associated with the wehrlite-gabbro contact zone. The Greenhills complex has some similarities to Alaskan-Ural type complexes.Reconnaissance exploration in the Dun Mountain Ophiolite Belt has identified PGM geochemical anomalies, but no follow-up work has been carried out. During the late 1800s and early 1900s, PGM were recovered as a byproduct of placer gold mining in Southland. Placer gold prospects with PGM potential include the Waiau River, deposits flanking the Longwood Complex and some Southland beaches.

Jan 1, 2002

By Steve Dillingham

A blast site incident has just occurred. Tensions are high, and, as the blaster, you’re in charge of the crisis at hand. Your mind is reeling, your thoughts frantic. The main areas of concern for you at the scene are to deal with immediate problems...aid the injured, take a head count, assess the damage, call emergency response, contact company headquarters, calm the neighbors, update your customer, and respond to the press on site. You feel as if all the bases have been covered...but, then again, have they? One of the biggest mistakes blasters and their companies can make is not including their Insurance carrier in the critical on-site accident procedures and emergency call list. Unfortunately, many companies believe that they are immune to the perils that can often, within a matter of minutes, create chaos that only happens to someone else.

Jan 1, 2002