Search Documents

By D. S. Case

"Following a brief explanation of the land arrangements under the Alaska Native Claims Settlement Act, this paper will examine both a mineral exploration agreement and a mining development agreement negotiated between two large mining companies and two different Alaska Native institutions. One of the institutions is a village corporation involved with an exploration agreement and the other is one of the Alaska Native regional corporations, which is party to a mining and development agreement with Cominco Alaska for the development of the Red Dog lead and zinc mine.Special attention will be given to the factors to be considered when dealing with small aboriginal owners with few resources in the context of an exploration agreement, including development issues which must be considered early in the process. The paper will also discuss the unique royalty and taxation structures developed for the Red Dog Mine Agreement as well as environmental issues. The paper will also consider the ways in which the cultural and differing economic interests of an aboriginal owner and a large mining company have been accommodated in the both the exploration and development agreements"

Jan 1, 1998

By Grossi M, Baiden G

This paper describes a new mine backfill method based on a newly invented binder with several years of test results from laboratory and on- site applications. The new binder has several advantages over traditional Portland and slag cement binders. One tonne of the new binder can replace two to three tonne of Portland cement when used to consolidate backfill and can result in the same compressive strength within seven days. When comparing backfill slurries of the same pulp density, the new binder attains more volume of in-place backfill mass than Portland cement because of the high crystallisation of water, resulting in tightly filled stopes. The crystallisation of the water provides for less or no de- watering in the backfill stope and easier transportation of the backfill slurry. Pastefill performance can be achieved by using pulp densities typical of a hydraulic backfill and the new binder, all the while transporting with the same ease of hydraulic fill.

Jan 1, 1998

By Ignacy A. Lipiec

The advantage of microorganisms used in bioleach systems to conventional chemical reaction systems is that these apply the available energy more precisely where it is needed, either directly onto the mineral of interest or by efficiently catalyzing the production of a reactant. The literature cover the range from empirical models used in describing macro heat balance in heaps to detailed studies relating the micro heat effects of bacteria adhesion energy to the surface of minerals. In this paper, the heat effects are reviewed in a general way describing bioleaching in two macro systems, heap leaching and slurry bioreactors. The micro scale heat effects is the reactions and conditions at the microorganism scale, including the mechanism of leaching and bacterial behavior.

Jan 1, 1998

By H. Sieber

Multilayer samples of tantalum and aluminum with the composition of Al-25Ta were prepared by cold rolling of elemental foils. The microstructure and phases were characterized by XRD, SEM and TEMISAED and the reactive phase formation was examined by DSC and DTA measurements in multilayer foils rolled for different deformation levels. The rolling procedure yields a decrease of the Ta particle size in the Al matrix and also results in the formation of a multilayer structure with a thickness of the elemental foils down to 200 nm in average. No phase formation is observed during the cold rolling procedure. While XRD and DSC measurements show no phase formation up to the melting of aluminum for samples rolled up to 40 F&R (fold and rolling) passes, in samples rolled for 50 or more F&R passes a first phase formation reaction yield an interfacial layer of TaAl3. Contrary to former studies in the investigated cold rolled Al- 25Ta multilayers the reaction starts at temperatures as low as about 340°C. The first stages of the reaction are associated with two exothermic maxima, that increase in amplitude and shift to lower temperatures with increasing number of F&R passes. At higher temperature the TaA13 reaction layer thickens very sluggishly and yields a third exothermic maxima at about 600°C. Isothermal DSC scans show the reaction is not finished for samples containing elemental particles larger than 1 pm after annealing at 550°C for 5h. In all the investigated samples no Al- Ta phase other than Tad3 was observed to grow for heat treatments up to 800°C. Multilayer samples heated up to 1400°C show a morphology consisting of small AITa2 particles embedded in a single phase TaA13 matrix. The multilayer microstructure and reaction product morphology are characterized by SEM and TEM investigations in cross-section and plan view geometry.

Jan 1, 1998

By D Crequer

A Peer Review Panel for the Golden Cross Mine in the upperWaitekauri Valley, Coromandel was initiated in December 1989, before mining, as a requirement of the conditions of the Mining Licence and Water Rights. The panel's function is as a technical audit and advisory team - to provide independent technical review of design, construction, and execution of mining operations, slope remediation works, and reclamation/mine closure activities. The primary role of the panel is to act in the public interest by providing assurance to regulating authorities that the design and application of on-site mining operations accords with 'good industry practice'. Panellists are not involved in design nor as advisers, although until 1997 when explicit terms of reference were written, the panellists were a sounding board for some operational proposals. The panel functions to ensure that best mining industry technical standards are met. The costs of the peer review process are met by the mining company. Review of mining operations includes environmental matters such as land rehabilitation and water quality. The focus of this paper is on the process of peer review for environmental management factors rather than for structural and mine engineering.

Jan 1, 1998

By W F. Bawden, J T. Paynter

This investigation involves laboratory testing and stability analysis of paste fill at the Golden Giant Mine. Site-cast samples are tested in unconfined, confined, and consolidated-undrained triaxial compression. Pore pressures during shear and consolidation characteristics are measured to determine both drained and undrained shear strength parameters and assess the potential for undrained loading. Liquefaction potential is also considered. A limit equilibrium solution is used to obtain factors of safety against failure of the fill during mining of adjacent stopes.

Jan 1, 1998

By M. E. Breitrick

Newmont Gold Company began full production in early 1995 at the Carlin East underground mine. The mine is currently producing at the rate of 900 tpd (1.000 stpd). for an annual production of 150.000 ounces. Approximately one hundred twenty five hourly and salary personnel are employed at the project for the estimated six-year mine life. Two mining methods are currently utilized at the mine. Longhole stoping with cemented backfill accounts for 70% of the total mine production. Conventional underhand drift and cemented fill accounts for the balance of the daily tonnage. In December 1996. Newmont purchased a new AC-Eickhoff ET-210 Roadheader. The machine went into service in mid-June of 1997 and is used in both longhole stope topcut development and cut and fill production at a rate of 225 tpd (250 stpd). The Carlin East mine is operated by Newmont Gold Company. The mine is one of four underground gold mines in production in northeastern Nevada owned by Newmont Gold.

Jan 1, 1998

By K B. Quast

During the prefeasibility stage of the mining cycle for a gold deposit, an evaluation of the ore leaching characteristics from various defined areas is essential prior to plant design. There are a number of simple laboratory tests which have proven successful in establishing gold and silver leaching kinetics, carbon adsorption and fouling, as well as elution characteristics. A number of case studies of carbon-in-pulp (CIP) simulation are presented which show excellent agreement between calculated and assayed gold and silver grades in feed and adsorbed on carbon which validate the methods used.

Jan 1, 1998

By Stephen H. Partney

Waste clay ponds are a necessary part of phosphate rock beneficiation. They are large, averaging 2.6 km2 (1 sq mile). They are unsightly in that they protrude 6 to 15 m (20 to 50 ft) above natural grade. Stabilization and reclamation is slow and they have had a history of catastrophic failure. Florida has never published a specific rule regarding the configuration or height of these ponds. But it has enforced several policies along these lines. The phosphate industry has been forced to make major monetary decisions that affect mine economics for decades. The Florida Bureau of Mine Reclamation believes that the direction of regulation has been solidified but changes are still anticipated. Phosphate rock has been mined in Florida since 1890 (Fig. 1). Three notable technological changes occurred in the industry that led to major shifts in mining technique and volume. By about 1915, hydraulic mining had been replaced by centralized washers. Hydraulic mines usually started at an outcrop in or adjacent to a stream of the pebble zone. Water was pumped out of the stream through high-pressure monitors and sand and clay were washed away from the pebble. Mobile grizzlies and screens were used in conjunction with animal and human labor to concentrate the pebble and haul it away. Populations were sparse and the clays washed into the stream were considered an acceptable price for the commerce. The clays were not voluminous because the pebble zone typically contained relatively small amounts of them. Machines largely replaced animals by 1910 and provided greater efficiency of production. Centralized washers replaced mobile trommels. They allowed greater ease of access to shipping routes by rail. Some clays were placed in mine cuts from 1915 to 1930. Some were dammed off to increase the capacity of a given site. Some of these also failed, leading to clay plumes that were visible all the way to the Gulf of Mexico. By concentrating the waste clays (slimes) in impoundments, the solids concentration had increased, making plumes persistent for long distances. There were complaints. But there was no litigation against the companies during that time. In 1930, flotation technology allowed the recovery of the phosphate from deeper zones. This was because the "concentrate" size phosphate rock was in the sand-size range and could not be screened out. Centralized beneficiation plants grew into a three-step process - washing and screening, feed preparation and flotation (Fig. 2). Reagent storage, safety and the flotation cell complex made the plants into large capital installations. Larger draglines were required to dig deeper into the matrix. These had dramatically larger production capacities, which were then figured into the overall material balance for a given plant. The number of operators shrank and the production per operator grew. Larger areas were being bermed off for waste clay storage. An economic incentive became apparent for storing as much waste clay as possible in each settling area. At the same time, the population was steadily growing and more eyes were watching the activities of the phosphate mines. Phosphate mining, focused on production and profit, was earning a bad name from its neighbors. When the subject of phosphate mining

Jan 1, 1998

By G. Belardi

A study has been conducted to assess a new wet beneficiation treatment for the recovery of the sulphuric-acid-soluble titanium oxide contained in the waste from an Italian TiO2-pigment facility. The waste is produced during treatment of a Ti-enriched slag and contains as main components TiO2 (54%, of which 42% acid-soluble and 12% insoluble), SiO2 (27%) and A1203 (6%). Eighty percent of the material is finer than 50pm. The first step was to ascertain the possibilities offered by size classification, wet gravity separation, froth flotation and wet high-intensity magnetic separation to improve the grade and recovery of Ti02 and reduce the SiO2 content. The next step was to optimize the operating conditions of the various separations and assemble them into a complete flow- sheet. Beneficiation ensures potentially 70% recovery of the TiO2 with a concentrate grade of 80%.

Jan 1, 1998

By Alexander Malahoff

The summit of L_ihi submarine volcano changed dramatically after seismic activity beneath L_ihi during the month of August 1996. Bathymetric re-surveys of the L_ihi edifice using SeaBeam, Simrad and deep-towed Reson-Focus multibeam systems showed the presence of new north-south striking fissures, normal faults and a new pit crater located at the site of a former 300-meter high volcanic cone. Comparisons between the pre-1996 SeaBeam data and the new bathymetry show a net loss of about 100 million cubic meters of rock volume on the summit. This loss is localized at a new pit crater -- the 300-meter deep by 1,300-meter wide Pele's Pit. Submersible observations with Pisces V show the northern edge of Pele's Pit to be bounded by a normal fault located north of the site of the former Pele's Vents cone that has disappeared into the new pit crater. A new hydrothermal field, the Ikaika Vents, extending from a water depth of 1,311 meters to 1,287 meters has formed at the northeastern edge of the floor of Pele's Pit. Submersible observations of these new Ikaika Vents during September 1996 showed vigorous venting at the site with extensive white-colored bacterial mats hanging off the rock face above the vents. Follow-up mapping and sampling of the vent sites during August 1997 showed vent temperatures of up to 198°C, dense populations of vent shrimps around the vents and a centimeters-thick veneer of fine-grained polymetallic sulfide mineralization along the rock walls above individual vents. The mineralogy of the sulfides shows a barite, chalcopyrite, sphalerite, and pyrite composition.

Jan 1, 1998

By Ernt. W. D.

A membrane based mixed extractant process was developed for selective removal of copper from waste acidic cupric chloride etchant solutions found in printed wire board manufacturing. The process uses a mixture of Adogen 381 (tri-isooctylamine), MOC®-45 (ketoxime) and MOC® 55TD (aldoxime) in a kerosene diluent. The mixed extractants recover the copper from a hydrochloric acid medium and transfers it to a sulfuric acid medium. The process also utilizes unique wetted membranes to separate the aqueous and organic phases. The driving force for these membranes is not pressure but the difference in surface tension between the two phases. By using these membranes, complete phase separation results. There is no physical entrainment contamination as found in conventional systems. The only cross contamination is the solubility concentration of one phase in the other. This however is less than 10 mg/l.

Jan 1, 1998

By Chi-Ming Chang

Alloy powders are commonly used in the purification of zinc sulfate solutions for use in standard electrowinning practice. The primary goal of this research was to study the use of zinc-lead alloys for similar reactions in the galvanic stripping of impurities from organic solutions. The effects of various parameters on the electrochemical behavior of commercially produced zinc-lead alloy powders were determined. A qualitative evaluation and summary of the influence of the more pertinent parameters on iron removal from di-(2-ethylhexyl) phosphoric acid (D2EHPA) by galvanic stripping is given. Water concentration, oxygen content and reaction temperature were the principal factors affecting the reaction rate and process efficiency. Activation energies were also calculated and indicated that the reaction changes from chemical to diffusion control .with increasing temperature in the range of 35" to 45°C. The results showed that zinc-lead alloy gave faster reaction rates with less sensitivity to process variables than SHG zinc as a reducing agent for galvanic stripping. The role of lead could be as cathodic sites for the reaction which enhances the zinc dissolution or anodic half reaction. The morphology of the zinc-lead alloy surfaces, before and after the reactions, supports this assumption.

Jan 1, 1998

By W. E. Lytle

Environmental permitting is a critical component for joint-venture projects located in the Commonwealth of Independent States (CIS). This paper presents the basic CIS regulatory environmental requirements for permitting of a hypothetical mining source and emphasizes air permitting. Topics which will be covered include: the Expertiza process, air pollution quantification, data requirements, and air pollution modeling protocol. A comparison will be made between permitting requirements for air pollution sources in the United States and a CIS country, Kazakstan.

Jan 1, 1998

By J. Gallagher

Henderson Mine has been transporting molybdenum ore using a rail haulage system for the past 21 years. Due to the age of this system, limited performance, and obsolescence, a capital investment decision was imminent. Henderson used this opportunity to evaluate other transportation methods and continuously improve their mining practices. These efforts resulted in a new mine plan for Henderson, which ensures that Henderson will continue to supply high quality molybdenum into the 21st century. This paper will discuss the dramatic changes taking place at the Henderson Mine as a new production level is mined. These changes include the installation of an underground crushing, conveying, and truck haulage system, as well as increasing the scale of the panel caving process. Each of these topics will be discussed, as will their rock mechanics and material flow implications.

Jan 1, 1998

Although anion exchange resins are widely used for gold recovery in Russia and the former CIS, accounting for almost 50 percent of gold recovery in that part of the world, the technology has not been adopted in the West, apart from one small operation in South Africa. This situation is likely to change as the gold industry heads into the twenty first century. With gold prices having declined steadily through the 1990's, mining companies are under great pressure to reduce costs and improve gold recovery. Most studies on the use of resins for gold recovery from cyanide solution or pulp have shown that this technology has the ability to achieve both these goals. Resins can also be used to recover and recycle free and complexed cyanide in gold plant tailings, which has the potential to significantly lower operating costs, and latest developments in this area of technology are discussed. Finally, recent studies on thiosulphate leaching of gold have'shown that this process is very well suited to the treatment of carbonaceous, preg-robbing ores from the Carlin trend (Nevada, USA), and elsewhere in the world, because the gold thiosulphate complex does not load on to carbon. Whilst this obviously benefits the leaching process, it means CIP and CIL are ineffective in this situation, and the use of ion-exchange resins for gold recovery from thiosulphate leach solution are discussed.

Jan 1, 1998

By Laura Bustemante, Bruce Vandenberg, Fred Huettig

Recent advances in solid-state, field portable, fast framing video camera systems and PC based frame capture hardware now allow blast imaging up to 1000 frames per second. Up to 8 seconds of data can be stored directly into the unit, downloaded to a PC or archived to a standard VCR without data compression. Since no film processing is involved, motion analysis can be performed instantly and on-site within a few minutes. This paper will describe the design features and applications of the KineView 1256P system and compare these with the analogous aspects of fii based cameras.

Jan 1, 1998

By Trevor Hamm, Nick Holl

"Cameco Corporation is operator of the world's richest uranium project, the Key Lake mine/mill complex, located within the Athabasca region of Northern Saskatchewan. Mineable resources from the Key Lake ore bodies with an average U,08 content of 2.5% will be exhausted by the year 2000 and open pit mining at Key Lake will be phased out at that time. The mill will continue to operate at increased capacity, using high grade ore from the McArthur River project, a new underground mine at a distance of about 80 km from the Key Lake site. The McArthur River ore with an average U308 content of about 15 % will be blended with separately stockpiled low grade materials from Key Lake with a U,08 content of about 0.1 %. The average (blended) mill feed grade will be about 4%, similar to peak concentrations found in Key Lake ore.The Key Lake ore tailings are presently being placed in the mined out Deilmann pit under sub-aerial conditions, using spigots and a highly efficient pit/tailings drainage system. The tailings resulting from the processing of the blended McArthur River ore will be deposited on top of the Key Lake ore tailings under sub-aqueous conditions. This staged approach shows distinct technical and environmental advantages over an alternative, fully sub-aerial in-pit deposition scheme.The first part of this paper presents an overview of site specific geotechnical and hydrogeological features found at Key Lake and details some of the extensive test and modelling work that was required for environmental impact predictions during the development phase of the facility. The second part of this paper deals with tailings modifications, innovative placement technologies and drainage methods that have been (and will be) employed at the Deilmann Tailings Management Facility {TMF) to produce a highly consolidated tailings body under non-buoyancy conditions. The application of this technology at Key Lake is expected to produce a tailings ""plug"" in the Deilmann TMF which will have a permeability similar to or lower than the original in-situ Deilmann ore, resulting in a minimization of contaminant mass loadings to the environment both during operation and after decommissioning."

Jan 1, 1998

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

"The results are presented herein of on-going laboratory investigations of heap bacterial oxidation as a pretreatment method for the recovery of sulfide-encapsulated gold from ore samples of the Rhodes Mining Lahoca deposit, located in northern Hungary. The ore contains just over 2 g Ault and as much as 6% sulfide, mostly as pyrite. Laboratory aerated column tests conducted at Colorado Minerals Research Institute (CMRI) showed that mild to moderate biooxidation of the finely crushed ore occurred rapidly in approximately three months, with cyanide gold recoveries of up to approximately 60%. The results contrast cyanide gold recoveries of less than 30% from non-pretreated ore. Mineralogical examination of biooxidized residues indicated that the mechanism of biooxidation of crushed ore was related to microorganisms following pathways along structural anomalies in the pyrite grains. Such selective biooxidation is an important result to minimize the biooxidation and aeration time and effluent neutralization costs in a commercial operation.IntroductionThis paper describes the development of a heap biooxidation process for the Lahoca gold project The Lahoca deposit is situated in northern Hungary, at the site of a former copper mining area. Lahoca is a large tonnage, relatively shallow, deposit amenable to open-pit mining Lahoca has the potential to produce I 00,000 ounces of gold annually for at least ten years at its minimum reserve base.The laboratory test work conducted initially by Rhodes Mining NL demonstrated that the Lahoca refractory ore is amenable to whole ore and concentrate oxidative pretreatment and cyanidation. Capital and operating costs, however, for such milled ore treatments were considered relatively high. Rhodes Mining subsequently evaluated heap leaching methods, particularly heap biooxidation pretreatment, as a process route that promised superior economics suitable for exploiting lower gold grade refractory ores.This paper focuses on the laboratory column (simulated-heap) biooxidation test work, particularly the proposed mechanism of selective microbial oxidation, wherein only a small amount of the sulfides are oxidized sufficient to allow commercially acceptable gold recoveries by conventional cyanide heap leaching. Selective or minimal biooxidation of sulfides is considered important to minimize biooxidation time and aeration requirements, as well as acid effluent neutralization costs."

Jan 1, 1998

By MacDonald AJ, Raffield MP

The South Deep massive orebody consists of 20 to 30 in of payable conglomerates ranging in dip from 11¦ to 20¦ and at depths of between 2400 in and 34(10 in. The mine design process selected a mining method with a proven record of application that could be adapted to overcome the inherent difficulties associated with the depth, thickness and structural influences of the South Deep orebody. A modified cut and fill mining method provides a concentrated and highly flexible method of extraction. An integrated destressing cut will enable the modification of the stress environment such that it is suitable for massive mining operations. The choice of backfill type and stoping width in the destressing cut ultimately determines the characteristics of the stress modification and, as such, is critical to the success of the cut and fill operation. This paper discusses the decision process undertaken to determine the optimum backfill type and stoping width combination in terms of, conditions in the destressing cut faces and in the massive mining environment. Numerical modelling has been extensively used to analyse arious scenarios to aid in the decision process.

Jan 1, 1998