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The Henty Gold Mine is a good example of a situation where conditional simulation and optimisation techniques may have useful impact on modelling of mineralisation distribution and ore definition. Much of the gold mineralisation at Henty is concentrated within an alteration zone which is both physically discontinuous and forms only a small fraction of the overall mineralised volume. The alteration units are mappable from diamond drill core and underground workings. Conditional simulation and optimisation techniques for ore definition have found considerable success in the open pit gold mining environment. For many reasons including computational efficiency, lack of consistent geological information, and lack of familiarity with ideas and methods among mine geologists, implementations of these methods in open pit mining have been comparatively simplistic. Modelling is commonly reduced to treating the sample data as a single geologic population. This paper discusses the application of the MP method (a particular implementation of conditional simulation and optimisation) to modelling the distribution of potential ore blocks in the Henty gold mineralisation. The approach allows the mine geologist to model both the spatial geometry of the alteration types and the gold grades associated with each alteration type in a single process. Options allow the geologist to include or exclude underground geological mapping and face sampling depending mainly on the abundance of drill hole sampling and the quality of the face sampling. An optimisation algorithm based on maximisation of profit from mining is used to assist in ore definition.

Jan 1, 2000

By Ron Lutz

In today’s world, production is the name of the game. We are all in business to make money. In the Quarrying and Mining industry the same holds true. The primary goal is to develop the best drilling and blasting program available to maintain uniform fragmentation to maximize production. Also we want to maintain drilling and blasting costs and minimize escalators. This paper is intended to discuss ways for all parties (quarry’s, blast service and drill companies) to attain this through understanding what can be done to help blasthole drilling and production. Blast designs and seminar’s emphasize the accuracy of drilling to produce better fragmentation. Blast design must also include basic concepts in the drilling process. The type of drill to be used for example whether it is a crawler or truck mount, top hammer or down the hole is important. Quarry operators have a role to play as well. They hold the key to the production of drilling. What the customer does or does not do has a direct effect financially to the drilling. The phrase of pay me now or pay me latter comes to mind. This paper will explore the detail of planning that is required by the quarry and/or blast service companies before a single hole is drilled. The drill must be able to meet the production need of the operation. The type of drill available and what can and cannot be done. The drill cost must be competitive. This paper will touch on comparison drill costs from 1967 to 1999.

Jan 1, 2000

By T. T. Chen

Gold in the Twin Creeks ore is primarily associated with arsenian pyrite. During pressure oxidation, the sulphides are solubilized, but part of the dissolved iron reprecipitates as jarosite and as an iron sulphate-arsenate-phosphate phase. The pressure oxidation products are subjected to cyanide leaching. The cyanide leach residues consist of quartz, gypsum, bassanite, anhydrite, small amounts of jarosite, an iron-sulphate-arsenate-phosphate phase, as well as trace amounts of orthoclase, rutile, pyrite, hematite and monazite; all these particles are dispersed in a fine grained matrix of illite-muscovite. The autoclave leach residues contain a small amount of carbonaceous matter. Many gold grains are detected on the surfaces of the carbon particles, and these gold particles are not leached during cyanidation. The gold particles are typically 0.1-0.2/Lm in size and commonly are embedded in the carbon surface or are coated with a K-AI-Si-S-O phase on the surface of the carbon. The gold grains are consistently associated with elevated CI contents (50-300 ppm Cl). The poor gold cyanide leach recoveries, which initially occurred in the Twin Creek developmental circuit under certain operating conditions, are attributed to the presence of chloride in the feed. This results in the formation of soluble gold chlorocomplexes in the autolcave and the subsequent sequestering of the gold on the surfaces of the carbon particles.

Jan 1, 2000

By V. R. Voller

"The World Wide Web (the web) provides a very useful resource for the enhancement of teaching and research dissemination. This paper advocates that researchers take control of this resource and become actively involved in creating web content. Two examples of the use of the web in a materials setting is provided. The first illustrates how a concept quiz for teaching can be developed. The second shows how a materials processing model can be run in real time over the web. The paper closes with a summary of some resources that can be used to create web materials.IntroductionA recent copy of a newspaper advertisement read""Share what you know, learn what you don't""This neat phrase sums up a powerful teaching and research philosophy. In an educational setting a prime motivation for research is to uncover the unknown and venture in directions previously uncharted. The balance to this search for knowledge should be a desire to share that knowledge with others; whether it be with students in the classroom or research colleagues in a wider setting.The .World Wide Web and its associated multi-media software offer a perfect platform for researchers to share their knowledge with an extremely wide sector of the research community. To enable the use of this resource researchers must take the power that the web offers them into their own hands and create products that take maximum advantage of the medium. It is key that researches at the forefront become directly involved, otherwise a potential powerful medium will not realize it's true potential, and colorful products with no core content will proliferate. The object of this paper is to outline two ways in which the web can be used to enhance teaching and research objectives."

Jan 1, 2000

By A. V. Tarasov, A. D. Besser

A processing flowsheet has been developed for treating substandard lead-containing polymetallic bulk concentrates and intermediate flotation products containing precious metals, which comprises oxidizing roasting in a calcination kiln and electrothermic smelting generating low volumes of off-gas. The proposed flowsheet also incorporates a dust collection system and sulfur dioxide recovery from off-gas. It is proposed to implement this process by using a reaction smelting technique. For this purpose, the charge to be fed to the smelting furnace after its calcination in a drum-type rotary kiln must have a ratio of sulfide sulfur to sulfate sulfur of at least 1 :2. Electric smelting makes it possible to produce lead bullion that also collects the precious metals contained in the feed, as well as copper-lead matte and slag containing zinc. The recovery of lead into lead bullion and into matte is approximately 83% and 14%, respectively (thus the overall recovery is 97%); the total recovery of gold and silver into lead bullion and matte is 98%; th\lt of copper into matte is 89%; the recovery of zinc into slag is 96%; and that of sulfur into sulfuric acid or gypsum is 90%. After the recovery of zinc from slag, the latter can be utilized in the construction industry.

Jan 1, 2000

By Ilija Ilic

Recovery of tin from tinplate and production of good-quality detinned-plate for further processing in ironworks has been the subject of interest for many years. Tinplates are mostly used for production of tin containers for food industry and consumer goods. The research carried out so far included determination of the parameters of dissolution of tin from tinplates by alkaline solution of NaOH and electrochemical recovery of tin from the alkaline solutions. During leaching, NaNO3 and methanitrobenzoic acid (MNBA) as oxidants were studied. By leaching the waste tinplate which contains 0.31 % of tin with a solution of 1.12 mol/dm3 NaOH, 0.26 mol/dm3 Na2CO3 and 0.09 mol/dm3 MNBA at temperature of 70°C for 60 mm, a degree of tin leaching of 97 % was attained. MNBA facilitates oxidation of Sn2+ into Sn4+ suitable for obtaining compact, and not spongy, Sn cathode deposit, as it was the ease earlier. Recovery of tin by electrolysis from solutions obtained by leaching was studied to determine the effect of electrolyte composition on the quality of cathode deposit and the degree of electric current efficiency. Experimental results obtained at a laboratory level were checked on an enlarged laboratory set up where continuos leaching of tin from waste tinplate and its electrolytic recovery from the solution obtained were carried out. The experimental set-up -operated under semi-industrial conditions, and about 500 kg of waste tinplate was processed yielding about 1.160 kg of tin (99 % Sn).

Jan 1, 2000

By Christoph Beckermann, Kai Liu, Richard A. Hardin

"A two-dimensional heat transfer model for transient simulation and control of a continuous steel slab caster is described. Slab thermal and solidification conditions are computed by the model as a function of time-varying casting speed, secondary spray cooling water flow rates and temperature, slab thickness, steel chemistry, and pouring and ambient temperatures. A solidification model that includes the effects of steel chemistry, cooling rate and mierosegregation on the solidification path is incorporated directly into the caster model. Comparisons between measured and predicted liquidus and solidus temperatures are given for two low alloy steels, and show good agreement. Predicted and measured slab surface temperatures recorded on an operating caster are compared with this transient model and show that the model can predict the temperature response at the slab surface. Results of several simulations are given to demonstrate the effects of changing casting conditions on the slab thermal profile and the solidification end-point. A control methodology suitable for online control of a continuous casting machine is described, and its ability to control the surface temperature profile by dynamically adjusting secondary spray cooling flow rates is demonstrated using the simulator. IntroductionIn order to remain competitive in today's world-wide market for continuously cast steel products, steel producers are finding that it is ever more important to implement process control and to develop a more thorough technological understanding of their casting process. By integrating process control and monitoring into both production and quality control, producers are better able to meet customers' demands for steel of the required quality, quantity, size, grade, and properties at the lowest cost. Computer models used for real-time/on-line prediction and control of continuous steel casters are fundamental tools to accomplish this. Accurate on-line prediction and control of steel solidification and heat transfer allows for more flexibility in caster operation by giving operators the ability to change casting speeds while keeping critical process parameters within required ranges. Such control 'capability also results in more uniform quality throughout an entire casting sequence from startup to shutdown. Furthermore, due to the unreliability of temperature sensors, and the lack of good sensors for important process parameters such as solidification end-point and liquid pool depth, computer-based control models are often the only available option."

Jan 1, 2000

By Nagahiro Saito, Takahiro Ishizaki, Daisuke Yata, Akio Fuwa

"Ternary compound-semiconductor, CuInTe2, film was deposited cathodically under potentiostatic conditions on titanium substrate from aqueous solution containing CuCl2, InCl3, TeO and HCI in this study.The deposition parameters such as electrolytic solution composition, potential and temperature were optimized· for electrodeposition of CulnTe2. Structural characterization of the: deposited film was also carried out using XRD and SEM. Electrodeposited films Were prepared and analyzed for their chemical composition using ICP. The ICP analyses showed that the stoichiometry of the films could be controlled by (1) the deposition potential and/or by (2) the electrolytic bath composition.1. IntroductionThe ternary chalcopyrite type compound semiconductors exhibit such electrical, chemical and optical properties that make them promising for photovoltaic devices (Kazmerski and Wagner 1985)(1). Many researches have been devoted to the characterization of these materials for over one and a half decades. High efficiency solar cells based on p-CulnSe2/n-CdS have been reported (Mickelson and Chen 1983)(2).The electrodeposited fil ns of semiconductors have more advantage than other physical and chemical deposition techniques; it is relatively easy and economic technique and the semiconducting properties such as band-gap variation, concentration of dopant stoichiometric composition and so on can be controlled with some accuracy. The electrodepositions of the ternary CuInS2, CulnSe2 have been reported by many workers (Hodes and Cahen 1986, Bhattachaya 1983, Singh et al 1986, Lokhande and can be prepared as both p-type and n-type. Therefore, its potential for application in optical and photovoltaic devices is one of the great interests. Bhattacharaya and Rajeshwar (1986)(9) reported the electrodeposition of CuInTe2 from an acidic bath· on indium tin oxide (ITO) and Mo substrate. Triethanolamine (TEA) was used as a complexing agent for indium. The electrodeposited CuInTe2 films were non-stoichiometric in composition under all their experimental conditions by electron-probe micro analysis (EPMA) and Auger depth profile analysis. In this paper, we report our results on the behavior .of Cu-In-Te electrodeposition from ·acidic baths; the preparation of CulnTe2 and the effect of bath composition on electrodeposited films obtained."

Jan 1, 2000

By J Hadjigeorgiou

The stability of open stopes in underground hard rock mines is influenced by several factors including the shape and size of the excavation, surrounding stresses as well as the degree of jointing. This paper presents a design methodology for stope analysis in jointed rock masses. The proposed approach relies on geological structural data to construct realistic three-dimensional joint network models. The stability of an open stope is determined based on a limit equilibrium analysis.

Jan 1, 2000

By G C. Reed, J M. Murray

During more than 100 years continuous mining of the lead-zinc orebody at Broken Hill, an immense amount of geological data has been collected about shear zones related to the orebody. The challenge to current mine geologists is to synthesise and interpret these data sets in a way that is applicable to production demands. Precise knowledge of the locations of major shear zones is important not only for the determination of ground conditions but also to develop an understanding of ore remobilisation along these structures. Traditionally, geological information has been collected from drill core and back and wall mapping underground, and interpreted on sections that are approximately 20 m apart. The recent introduction of MaptekÆs Vulcan software has enabled the shear zones to be modelled in three dimensions. The new three-dimensional shear models have been combined with seismic data from the Southern Cross area. The seismic data is collected from a microseismic monitoring system installed in the Pasminco Southern Operations in August 1996 (Rauert and Tully, 1998). The addition of seismic information to the shear zone models has led to a greater degree of certainty about the shear zone locations and has provided information about shear zones in areas yet to be drilled.

Jan 1, 2000

By K. Severin, B. Flanigan, P. Marion

“Plutonic-related” gold deposits in Interior and SW Alaska (Tintina Gold Belt) vary significantly in size, grade, vein/deposit morphology, depth of emplacement, distance from causative pluton and metal association. Metal associations such as Au-Bi and Au-As-(Sb-Hg) are a good empirical indicator of depth of emplacement and distance from causative pluton and have been used successfully in exploration. Results from a variety of analytical techniques also suggest a phenomenological cause for these metal associations, e.g. gold and bismuth have linked metallogenesis at high temperatures and thus are best correlated at deposits that are deep and/or close to causative intrusions.

Jan 1, 2000

By Dale Ramsey

Emulsion explosives have become the product of choice for many blasting applications and are not limited to just extreme wet hole conditions or special application environments as in the past. Today’s novel emulsion technology has evolved over many decades, allowing a great diversity of formulations, Emulsion explosives can be effectively designed to produce very high energies, cap sensitive high explosive cartridges to bulk blasting agents, with varying viscosities, stable VOD’s, excellent water resistance, long shelf life and sleep time. They are also conducive to the mixture of emulsion, An/F0 blends in varying proportions and are amenable to any type of sensitizer. The key to a stable, reliable and consistent emulsion formulation is the careful mixing of the internal phase, which consists of a solution of oxidizer salts suspended as microscopically fine droplets, with the surrounding continuous fuel phase. There are few blasting applications today where some form of an emulsion explosive cannot fit the application. In massive, hard rock, dense, tightly jointed and fine grained rock types, the emulsion explosives are the best choices in creating new fracture networks for good fragmentation with a few alternatives. In such environments, emulsions with expanded drill patterns often result in better economics than the use of straight AnLFo. This paper will cover emulsion formulations, sensitizing options, product testing, material handling, and blast optimization, Emulsion explosives characteristics have also proven to reduce adverse environmental effects such as noxious fumes, ground vibration, and airblast while still remaining cost effective.

Jan 1, 2000

By Kirk Yeager

All explosive formulations display some sensitivity to heat. A common technique utilized to measure an explosive’s response to thermal stimulation is differential scanning calorimetry (DSC). As DSC analysis is run on quantities of material easily handled in a laboratory setting, and is relatively inexpensive, it tends to be one of the more predominant tools utilized to determine potential thermal hazards of energetic materials. The analysis of energetic materials via DSC provides unique challenges, as both large energy outputs and significant production of gaseous products result from their decompositions. In addition, the unique thermal decomposition characteristics of ammonium nitrate (AN) based materials have also created difficulties in DSC analyses. A wide variety of techniques have been developed to study the decomposition of explosives. Traditionally, sealed glass capillaries were utilized to house samples. Recently, the introduction of specialty cells designed to withstand high pressures has enabled new sampling techniques to be developed. Analyses of explosives with both traditional and “high-pressure” cells will be compared and contrasted. Lessons learned about the application of both techniques towards analyzing thermal hazards such as incompatibilities will be presented. Inconsistencies in the results displayed during analyses of AN-based explosives will be highlighted. Recommendations on the best approach for analyzing the more problematic AN formulations will be given.

Jan 1, 2000

By S DeKruijff

The Mount Isa Mines Copper Mine in Mount Isa started producing copper in 1966. The Copper Mine gradually increased production rates to nearly six million tonnes per year. Over the last three years the mine has been in a gradual ramp down due to the reduction of primary ore sources and head grade. The majority of ore sources are predominantly in pillar retreat sequences bounded by multiple fill masses. There also a substantial lower grade resource delineated to the south of the main orebody. These remaining ore sources present significant engineering challenges to obtain a safe and cost-effective extraction. Stope designs have become increasingly complex and require additional engineering and operations input and analysis. This paper describes the major planning and operational challenges and issues associated with the stope design and extraction of an orebody in the later stages of mine life.

Jan 1, 2000

By Giuliana A. Zelada

This paper reports on a study of 43 compression load tests (five fully instrumented) and ten pullout tests of auger cast-in-place (ACIP) piles in sand. Eight design methods reported in the literature were used to predict the measured pile capacities. Ultimate load capacities of the ACIP load tests were determined using two different definitions of ultimate capacity and compared with predictions. Load transfer behavior was determined from a study of the fully instrumented pile tests and compared to predicted values. Recommendations are made regarding the design approach most appropriate for these foundations and the best procedure for estimating ultimate capacity from pile load tests.

Jan 1, 2000

By Marc Liebman

We present the results of a telephone survey of electric arc furnace (EAF) steel producers. This report characterizes the current status of EAF dust generation, treatment and disposal. It indicates the quantity generated, zinc content, other relevant constituents, and plans and trends that will impact on the quantity and characteristics of the dust generated. The survey covers EAF based steel producers in the United States and Canada. It identifies the processors currently employed, opinions about the use of these processors and services, as well as new technologies being considered.

Jan 1, 2000

By M Brooks, M Nelson

A fundamental study was carried out on super pit sulphidic gold ore to establish the most influential flotation characteristics which were subsequently used in the development of an optimum flowsheet to achieve best economical recovery of gold. In developing the flowsheet, consideration was given to existing operational constraints in the treatment of the Super Pit ore. The fundamental study also included an innovative diagnostic investigation to establish the location and value of gold in the major mineral assembly of the super pit ore from a metallurgical rather than a mineralogical perspective. This study mapped a metallurgical fingerprint of the major types of super pit ore in relation to the location and association of gold.

Jan 1, 2000

By S Brown

With oxygen conditioning routinely used in both the lead and zinc circuits at Pasminco Elura Mine a more sophisticated method of determining oxygen demand was required. It is known that different ore types have different oxygen consumption rates, however oxygen is added at a fixed rate regardless of ore type in the plant. Therefore, a simple laboratory test was devised to measure the oxygen demand of ores. The paper describes the technique employed, and provides an interpretation of the results. These data, together with pulp chemical measurements (Eh, pH and EDTA extraction data) were correlated against laboratory flotation performance to establish the relationship between oxygen demand and the position of the grade/recovery curve.

Jan 1, 2000

By K. H. McDaniel, L. Griswold

The Waste Isolation Pilot Plant (WIPP) is adding a third fan to supplement its two existing main fans. The third fan will operate in parallel with the two existing fans. An engineering analysis conducted in 1995 identified the need for improved system availability and efficiency. The WIPP, located near Carlsbad, NM, is a US Department of Energy (DOE), Carlsbad Area Office, facility that is designed to permanently dispose of US defense-generated transuranic waste in a deep, bedded salt deposit. Engineers at the WIPP performed a feasibility analysis for modifying, supplementing or replacing its two main mine fans. Since the centrifugal fans were installed in 1988, multiple operational and performance concerns have been identified. A comprehensive engineering study was conducted (McDaniel et al., 1997) to identify and quantify operational concerns, evaluate possible alternatives and recommend an optimum solution. The study indicated that adding a third single-duty centrifugal fan similar to the two existing fans and equipping that fan with Inlet Van Controls (IVCs) was the best choice. This alternative provided the most desirable combination of operational readiness and improving system performance. The fan installation project accommodates several operational and scheduling con¬straints. WIPP was scheduled to receive waste in May 1998. This milestone is proceeded by an operational readiness review. Fan installation could not be allowed to compromise the WIPP 's ability to declare facility readiness. Therefore, operational disruptions during the system tie-in had to be minimized. All engineering for the project has been com¬pleted, and physical modifications were begun in July 1997. The project was completed in 1998.

Jan 1, 2000

An extensive study was carried out to evaluate the performance of Outokumpu OK50, OK38 and Maxwell MX14 cells at ComincoÆs Red Dog flotation concentrator in Alaska. Tests were conducted by varying operating conditions of the cells installed in different circuits in the plant. The hydrodynamic and gas dispersion properties were measured and the metallurgical performance of the cells was evaluated for each condition used in the tests. This paper highlights the importance of superficial gas velocity, bubble surface area flux, gas hold-up, power consumption, residence time distribution and froth flow behaviour in optimising cell performance. The findings of these tests provide valuable insights into selection of the best cell operating conditions to optimise circuit performance.

Jan 1, 2000