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The perception of New Zealand as an exploration destination has improved compared with other countries. There has been a realisation that New Zealand's potential is greater than previously thought. Other countries are not as attractive as before, and explorers are looking at alternatives that are geologically prospective and politically stable.   New Zealand is regarded as geologically prospective, especially for gold, with potential for world class deposits. It is also prospective for other metals, coal and industrial minerals. New Zealand is politically stable, and has an economy that is attractive to overseas investors. It is one of the least corrupt countries in the world, which overseas companies see as providing a high degree of certainty for investment.   New Zealand has good opportunities for investment in gold exploration at present. Otago has been the focus for new companies and is the favoured exploration location. Otago is regarded as very prospective, and hosts New Zealand's largest gold deposit at Macraes. There is potential for other similar deposits elsewhere in Otago.   The mineral industry previously had an excessively pessimistic view of New Zealand, which has resulted in little new investment in New Zealand for some years. Previous pessimism is turning to optimism, and there is increasing interest in New Zealand as an exploration destination by overseas explorers.

Jan 1, 1997

By Georgi N. Shoushoulov, Ventsislav D. Bozhilov

The mining conditions in the Meden Rid mine at levels below 1000 m from the Earth's surface are specific and rather severe. The rock temperature is about 40-45°C. The air humidity in the workings is approx. 80-90%. There is a limited capacity for additional fresh air supply. The air supply and distribution systems in the mine are very complicated. The airflow recirculation is due to the existing arrangement of the main fans. Certain accidental phenomena are difficult to predict. All these conditions create possibilities for heat and mass exchange between the rock and the air current thus hampering the control of the ventilation and air-conditioning in the mine workings. The changes in the temperature and humidity in certain characteristic places of the development and extraction workings are predicted. The refrigeration output required and the arrangement of the air coolers are also determined. A new ventilation and air- conditioning scherne has been developed. The new ventilation- cooling designs for levels between 1000-1200 m beneath the Earth's surface are based on the use of portable refrigerating machines having low water flowrate as well as heat-insulating and waterproof materials and methods for preliminary cooling of the orebody within the mining block.

Jan 1, 1997

By W. M. Cross

The use of fillers and reinforcements for plastics has increased considerably over the past few decades. For example, in the 1980's the average growth rate of filler use was 5.8%. [Katz and Milewski, 1987] Similar filler use growth rates occurred in the 1970's due largely to the increase in price of petrochemical starting materials for plastics. While filler use is still sometimes predicated on the cost benefits associated with their addition to the plastic, other mechanical and performance advantages associated with filler addition are being realized, and account for most of the increased usage. Plastic filler types are many and varied, and include both inorganic minerals/metals and organic compounds, with the former type being, by far, the more common. Common mineral fillers include oxides, including both natural and synthetic silica; carbonates, particularly calcium carbonate; clays such as kaolin; and silicates like mica and talc. It has been recognized that a number of factors influence filler performance, including particle size, shape, surface area, and hardness to name a few. In addition, the interaction between the filler and the plastic is of paramount importance as this interaction will determine the wettability, bonding and the adhesion between the two materials, and ultimately, the mechanical properties of the composite. Froth flotation has long been recognized as a viable process to separate different mineral types. [Leja, 1982] Prior to flotation the minerals are liberated from the ore by comminution. The mineral particle size range produced by this comminution process is typically between 300 and 10 microns. This size range is also typical of mineral fillers for plastics. The size similarity between mineral fillers and minerals concentrated by froth flotation is only one of many similarities that can be found.

Jan 1, 1997

By Wayne J. Nordstrom, Dennis L. Murr, James E. Wennen

National Steel Pellet Company (NSPC) conducted pilot scale testing and computer simulation studies which indicates that the capacity of the secondary grinding mill could be increased and that concentrate grade improvement could be expected with improved classification in the grinding circuit. Based on these studies, a decision was made to modify one secondary ball mill line at NSPC to include both cyclone and screen classification with magnetic separation applied to the circulating load. This paper will briefly discuss the studies leading to the decision to modify the circuit, the design of the modified circuit and the initial start-up and operating experience.

Jan 1, 1997

This manual provides basic practical instruction on the inspection of driven piles. It covers the essential components of pile driving, such as the pile driving hammer, hammer accessories, the pile and soil, and frequently encountered test methods in an uncomplicated, yet knowledgeable, and practical manner. Insight is given into the methods of installing the foundation, dealing with the cranes which do the lifting, the hammers which do the driving, the leads that guide the hammer and pile, the compressors which provide the external power when required, and finally prevalent analysis tools and testing instrumentation and procedures which enable you, the Inspector, to do your job. This DFI Inspector's Manual for Pile Foundations will help the Pile Inspector who has limited knowledge of pile foundations. Perhaps this Inspector has been pressed into service at a moments notice; a few helpful hints and suggestions to him are desperately needed and he can look here for the basics. It is also useful for the experienced Pile Inspector as a reference guide. However, this manual is not a detailed check list of every possible scenario and detail which could ever be encountered. There are other sources available which give more detailed descriptions (and should be consulted by the Inspector when appropriate; a list of this additional reference material is provided and suggestions made in appropriate chapters of this text). The current manual is more a brief "textbook overview" with some of the more important aspects given at least some emphasis so that the Inspector has some direction and hopefully helps to produce a safe, yet economical, foundation.

Jan 1, 1997

By Jr. Foot

EIMCO Process Equipment Company has introduced the new SmartCell series of conventional flotation cells. The flagship of this new development is the 5000 ft3 cell that is the largest available in industry. This new series of cells includes a cylindrical tank design, a conical draft tube and froth crowder. Optional air control, wash water addition and embedded expert control are available. A discussion of the design parameters, energy efficiency, testing, and commercial plant results are presented.

Jan 1, 1997

By Frederick B. Henderson

The US Environmental Protection Agency (EPA) has tried many regional and laboratory efforts to develop measurement and monitoring techniques using environmental remote sensing technologies. In 1997, the agency established the Advanced Measurement Initiative (AMI): This is a eadquarters-level program, operating under the auspices of the EPA Office of Research and Development. The program is one result of the April 30,1996 White House Conference on Advanced Monitoring of the Environment. The EPA was encouraged to work with other federal agencies to leverage its remote sensing capabilities and use them to improve the efficiency, cost-effectiveness and flexibility of environmental measurement and monitoring for regulatory compliance and reinvention. During the fall of 1996, the EPA and the Department of Energy developed an interagency effort to broaden the use of governmental technologies for environmental measurement and monitoring. In addition, the EPA and the National Aeronautics and Space Administration (NASA) conducted joint workshops on the use of NASA remote sensing and other technologies for water quality and pollution applications. In the meantime, the EPA proceeded with an industry-proposed workshop to explore ways to cooperatively examine new research and to develop commercial remote sensing systems. It also examined how these systems might become accepted by the EPA in the regulatory and compliance processes. In particular, industry was interested in where new remote sensing capabilities might fit in with EPA's efforts at regulatory reinvention. Historically, the mining and petroleum industries have been reluctant to experiment with or use environmental remote sensing. They were concerned with the unknown liability from potential discovery of previously unknown environmental problems. Moreover, resource industries have been reluctant to use remote sensing for environmental applications where the EPA did not accept such data or information as part of the compliance process. Acceptance by the EPA of these advanced measurement and monitoring technologies (AMMT) will be a major reason for industry's increasedd use of remote sensing in environmental "applications for regulatory compliance. In July 1997, the EPA Office of Research and Development hosted at the Colorado School of Mines a stakeholders workshop on the AMI program and industry-government collaboration. The workshop's aim was to demonstrate the usefulness of AMMT technologies for environmental applications. Stakeholders included the mining and petroleum industries; environmental services companies; state environmental agencies and local governments; remote-sensing, value-added companies and data suppliers. The workshop used specific technologies and applications as a way to develop collaborative demonstration projects for several AMMT technologies covering different environmental problems. The workshop focused on the use of highly sensitive hyperspectral (very narrow spectral bands), geographic information systems and surface mapping to identify active acid-producing mine dumps and wastes from benign wastes at Leadville, CO. NASA's advance infrared imaging spectrometer (AVIRIS) was the instrument used. It was developed at California Technology's Jet Propulsion Laboratory. The EPA, the US Bureau of Land Managment (BLM), the US Geological Survey and several environmental service contractors sponsored the overflight and data evaluation. The AVIRIS study demonstrated reliability (95% correct surface mineral identification) and cost-effectiveness of this technology to accurately map and discriminate active acid-producing mine wastes from benign wastes. It could also predict which streams would be effected by acid and toxic mineral drainage. The BLM'said that the AVIRIS overflight could save it $500,000 a year in surface sampling costs at Leadville. The AMI workshop further outlined five 1997 funded AMI projects of potential interest to the mining industry. They were: ? Mine waste characterization using remote sensing methodologies at Asarco's Ray Mine in Arizona. ? Predictive emissions development and testing in

Jan 1, 1997

By E. H. Christiansen

The most valuable gem- quality red beryl comes from the Wah Wah Mountains of south-western Utah (Fig. 1). Red beryl occurs as a secondary mineral in topaz rhyolite. Marketable crystals from the Wah Wah Mountains have been produced from the Violet Mine, operated on a limited scale since 1976 under the ownership of the Harris family of Delta, UT. From 1989 to 1995, production from the mine amounted to more than $3 million with an inventory of several million dollars of unsold gems (Harris, 1995). In 1994, Kennecott Exploration leased the mine and surrounding claims to determine reserves and feasibility of gem recovery. Mining and exploration activity are continuing. Previous work on red beryl has dealt mainly with crystallographic, chemical and optical properties of the crystals (Shigley and Foord, 1984) with only general descriptions of the geology (Ream, 1979). However, the conditions needed for formation of red beryl have not been well constrained. It is generally proposed that beryl originates by precipitation in fractures and vugs from high-temperature gases as they are released from slowly cooled rhyolite lava. Dozens of topaz rhyolite flows and domes, similar in composition to the beryl-bearing flow in the Wah Wah Mountains, occur across the western United States (Christiansen et al., 1986). All of these flows devitrified to form vapor-phase topaz and locally other vapor-phase minerals such as bixbyite, garnet, hematite, pseudo-broo- kite and fluorite. But the occurrence of beryl is rare. Even within the rhyolite flow that hosts the red beryl, the productive open pits comprise only a small fraction of the surface area of the flow. Apparently, the conditions that favor the formation of red beryl are rarely achieved. Geologic setting The rhyolite flow that hosts the red beryl deposit lies along the eastern flank of the Wah Wah Mountains (Fig. 1). Prevolcanic rocks consist of Proterozoic, Paleozoic and Mesozoic sedimentary rocks that were folded and thrust to the east during the Sevier orogeny. Cenozoic volcanism began about 34 Ma. It consisted mostly of large volume dacitic ash flows and lesser volumes of low- silica rhyolite and andesitic lava flows. Beginning about 23 Ma, the style and composition of volcanism changed to smaller-volume, ash-flow and dome-forming eruptions of high-silica rhyolite and trachyandesitic lava. These rocks form the Blawn Formation of which the beryl-bearing rhyolite is one member (Best et al., 1987). Abbott et al. (1983) reported a K-Ar age of 22.1 + 0.8 Ma for this flow. It is probably the oldest topaz rhyolite flow in the Wah Wah Mountains. A subsequent episode (12 to 13 Ma) of bimodal magmatism produced the Steamboat Mountain Formation. The rhyolitic part of that is locally topaz-bearing. Displacement on the late Cenozoic extensional faults that formed the north-trending mountain ranges began about 22 Ma. Geology of the Violet Mine The rhyolite that hosts the red beryl deposit is part of a flowldome complex that overlies nonwelded tuff of cogenetic origin. This rhyolite is exposed over an area of about 9 km2 (3.5 sq miles) (Fig. 1). An unknown additional portion of the rhyolite is concealed beneath younger mafic lavas and sediments.

Jan 1, 1997

The Mount Whaleback iron ore deposit at Newman, Western Australia comprises the largest known continuous iron ore deposit in Australia, originally with a Measured Resource in excess of 1700 Mt of hematite ore. The deposit occurs within the Hamersley Province which forms part of the Pilbara Block in the NW of Western Australia (Figure 1). The Mount Whaleback iron ore deposit, together with a number of discrete iron ore bearing satellite orebodies in the Newman district, contributes to the Newman Lump and Fines products. Extensive quality control systems are utilised from mining to shipping to ensure that each product meets a narrow geochemical target grade range.

Jan 1, 1997

By G. Deschenes, P. J. H. Prud'homme

A laboratory study was carried out to evaluate the effect of oxygen and lead nitrate on the recovery of gold by cyanidation of a free milling gold ore, which contains 0.4 % copper as chalcopyrite. Efficient gold extraction is achieved only under specific conditions. The recovery of gold was increased from less than 90% to up to 98% by addition of lead nitrate. In the pre-leaching, the kinetics of oxidation of soluble sulphides are not an accurate indication for the length of the treatment. Even though the consumption of cyanide was reduced due to the inhibition of the dissolution of chalcopyrite by increasing additions of lead nitrate, cyanide consumption had to the held above 1.85 kg/t to maintain good recovery of gold. The continued addition of lead nitrate above 300 git had no impact on the recovery of gold. It was also found that the addition of lead nitrate at the start of cyanidation gave the same performance as when added during pre-leaching. The addition of oxygen increased the recovery of gold by 1.5%. The concentration ofNaCN had to be maintained in the range of700 mg/L because of the high concentration of copper in solution. The recovery of gold dropped significantly when the average NaCN concentration fell below 640 mg/L. Application of the findings of the laboratory study at the industrial scale led to improved plant performance.

Jan 1, 1997

By Michael Brittan

Diagnostic regression analysis has been used as a tool to improve the recovery efficiencies of numerous gold mills, yielding significant revenue increases. In the course of the analyses it has generally been found that ore head grade is a statistically dominant variable affecting the overall gold recovery. Higher grades invariably generate higher recoveries. Examples are given from several operations in the world's two largest gold producing countries, South Africa and the United States. The plants considered cover the treatment of both oxide and refractory ores. A simple generalized model is presented relating tails to head grade. Since ore grade variations are beyond operational control, operators should not be held accountable for decreases in recovery caused by lower head grades. Conversely, the ore must take credit for many a recovery increase. Rigorous metallurgical test work, feasibility analysis, production planning and budgeting should allow for recovery variations due to grade fluctuations. Since the phenomenon is a reflection of ore geology and mineralogy, which are ore specific, comparison of recoveries at different times or sites is not meaningful without a detailed understanding of the mineralogical constraints on gold liberation.

Jan 1, 1997

By John Keay, Douglas R. Shaw, Gregory J. Olso

Rhodes Mining NL, Perth, Australia, is developing the Lahoca Gold Project which is located in Hungary, about 30 km from the town of Eger. The preliminary resource is estimated to contain approximately 1.5 million ounces of gold. The project is being evaluated for an annual process capacity of 2 million tonnes. The test samples contain just over 2 g Ault and 6% sulfur as sulfide. Copper and arsenic levels are approximately 0.2 and 0.1 %, respectively. The ore is refractory due to submicroscopic gold occurrences and structural associations with pyrite. A small amount of the gold is finely encapsulated in quartz. Approximately 30% of the gold in the crushed ore is soluble in cyanide and up to about 55% is cyanide-recoverable with ultra­fine grinding. The ore has little preg-robbing ability. Metallurgical test work done by Colorado Minerals Research Institute (CMRI) and other investigators has shown that as much as 85 to over 90% of the gold was recovered by the relatively severe conditions of pressure oxidation or roasting of the whole ore or a flotation concentrate. The Lahoca ore responds to flotation with gold recoveries of 87% into a low grade concentrate. Subsequently, with a view toward defining a process route with potentially more attractive economics, Rhodes Mining and CMRI conducted an extensive review of biooxidation technologies and concluded that, in particular, heap biooxidation methods promised lower process costs which normally are associated with heap leaching. Based on the study, which included the analysis of the closely related practices of copper dump/heap bioleaching now well established in that industry, CMRI conducted simulated heap biooxidation experiments which evaluated factors such as ultra fine ore crushing, agglomeration techniques, heap design, forced aeration oxygen supply, and whether or not the heap is irrigated. Separate flask biooxidation tests at Little Bear Laboratories showed that the finely crushed ore is biooxidized readily, with a near linear relationship between sulfide oxidation and gold cyanide solubility. Gold recoveries of as high as 66% have resulted after biooxidation of crushed ore. This paper highlights the metallurgical developments of the Lahoca project, and focuses on recent biooxidation laboratory test work aimed at enhancing the treatment of crushed ore.

Jan 1, 1997

By Jeffery S. Thompson, Harry Hinds

Recent advances in the development and application of the DuPont Activator Technology are discussed. Activators are catalysts of gold dissolution in cyanide solution. Plant testing of this technology in the vat leach circuit of the Homestake mine in Lead, South Dakota, showed increased gold recoveries ofup to 5%. Homestake has licensed the technology for this application and is in the process of full commercialization. Results from testing additional ores on a laboratory scale are also presented. These results indicate this technology will also increase leaching at much lower cyanide concentrations while achieving the same gold recovery.

Jan 1, 1997

By Chuck Hornaday, Brad Miller

Geosynthetic clay liners (GCLs) are manufactured barrier layers containing a high-quality sodium bentonite clay attached or adhered to geotextiles or a geomembrane. The GCL's low permeability and high strength make it an ideal replacement for low permeability soil or clay liners for mineral extraction and processing containment applications. This paper will discuss the advantages of utilizing a GCL versus compacted clay in containment applications. Some of the advantages include: the GCL's lower permeability (5 x 10-9 centimeters per second (cm/sec)) and corresponding better composite liner leakage protection, the GCL' s greater resistance to desiccation, differential subsidence and freeze­thaw, and lastly, the ease and speed of installing the GCL. This paper will also detail a number of important case studies related to the mineral extraction and processing industry. These case studies include using GCL in two large reclamation capping projects, as a secondary liner in two gold heap leach pads, as a composite liner in a dam for stormwater runoff control, and lastly, as a primary liner for a tailings runoff diversion channel.

Jan 1, 1997

By Harry M. Castrantas

Caro's acid (peroxymonosulfuric acid-H2SO5) is used to destroy cyanides in tailings slurries due to its rapid reaction and low capital and operating costs. Due to its instability, Caro's acid is generated at the mine site using a hot or cold process. The majority of gold mines that use Caro's acid use the FMC hot process. In the FMC hot process, it is not necessary to cool the Caro's acid to minimize decomposition since it is used immediately upon generation. In contrast, the cold process uses a chiller to cool the raw materials and product. This paper will show, using laboratory and field data, that there is virtually no difference in Caro's acid yield between the cold and the FMC hot processes. Caro's acid yield depends on the mole ratio and concentration of sulfuric acid and hydrogen peroxide and is independent of operating temperature.

Jan 1, 1997

Several years ago, North American mining companies began to realize they needed to expand their spheres to remain viable. This strategy has been successful, according to Robert W. Schafer. Today, companies from other continents have also recognized the need for an international view for long-term growth and viability, he said. Schafer is vice president for exploration with Kinross Gold. He was the program chairman and moderator of the keynote session at the 1997 SME annual meeting, held in Denver, CO, Feb. 23-27. The theme of the meeting was "Minerals - Serving the Global Community." A record attendance of more than 6,000 people participated in the meeting, which featured 415 exhibitors occupying 582 booths. The title of the keynote session was "Corporate Perspectives on a Global Minerals Industry." Each of the three keynote speakers discussed a different perspective of a global minerals industry.

Jan 1, 1997

By Stewart R. D, Lawrence W, Youl M. J

The trend towards contracting by major coal mining companies such as BHP Coal and MIM Ltd is examined. Reasons why this trend is occurring are discussed and the concept of partnering is examined. Two case studies are given: the Mt Owen Mine in the Hunter Valley, NSW and the South Walker Creek Mine in the Bowen Basin, Queensland.

Jan 1, 1997

By Kentwell D. J, Cusak C. J, Harvey-Kelly F. E L, M D. Goodz

The Morning Star Gold Mine presents an example of a prolific operation with considerable historical records, mine workings, drill hole logs and countless plans from greater than 20 adjacent mines which have now been consolidated to form the current project. Implementation of 3D computer modelling in the planning stages has provided an additional tool to integrate and refine geological models as a guide to some exploration strategies. It has allowed for a re- interpretation of the host rock units, dimensional constraints, new exploration extensions and provisional resource modelling. The initial consideration of this project was to integrate 135 years of mining history into a single database. Each historic mining area had an unrelated mine grid, often established parallel to the long axis of their main stopes; some were based on magnetic or true north. Survey plans were in chain, imperial or metric units. Through the manipulation and rotation of old grids, previously unrelated mine workings began to form continuous mineralised zones, with unmined portions still remaining in between the existing development. Furthermore the current drillhole database of >433 holes showed numerous confirmatory intersections of new mineralisation. A series of tiered tables were created within a relational database to derive guidelines for assessing data to attribute a Mineral Prospectivity Value [MPV] based on key indicators of mineralisation. Indicator logging now forms the basis of geological descriptions.

Jan 1, 1997

By Johnson N. W, Manlapig E. V, Alexander D. J, Franzidis J. P

The importance of the froth region on flotation performance is often emphasised in the literature. It is well-known that decreasing froth depth or increasing air flowrate results in increasing cell recovery at the cost of lower concentrate gra

Jan 1, 1997

By Bruington T, Perkins J, Hutton R

Natural resource developments are among the largest and most challenging projects taking place in the world. They involve capital intensive investment with long lead times and the management of geological, market, technical, operational and financial issues. A clear strategy is required to manage these projects and this strategy is underpinned by a development Philosophy.

Jan 1, 1997