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By Jay Rodgers

There has been a longstanding acceptance that burden plays a major role in the magnitude of ground vibration amplitudes generated from surface blasting. Much of the data that this belief is based upon is empirical in nature and may or may not represent an example of false inference. Recent published reports have rightly questioned the influence of burden and confinement on blast vibration amplitude, suggesting that the fracture condition of the rock mass is a better indicator. The increased investment in electronic detonators as a tool to control ground vibration amplitudes demands an understanding of vibration production detailed enough to make use of the vastly improved timing accuracy that they provide. A more accurate relationship may be found if we strip away the assumptions of the past and search for the underlying mechanism of vibration production in surface blasting. We must answer the question: What happens at or near the borehole when an explosive charge detonates that produces ground vibrations?

Jan 1, 2003

By M, C Silveira, C Ellice, D Christensen

Peak Gold Mines (PGM), a member of the Rio Tinto Group, is an underground and open cut gold mining operation located near Cobar, NSW. A multi-phase study was initiated in 2001 in support of developing a dry æmoisture store and releaseÆ cover system design for the PGM tailings dam, which contains potentially acid-forming tailings material. The first phase consisted of characterising the tailings and potential cover material (waste rock from an open cut operation) as well as soil-atmosphere cover design modelling. The second phase involved construction of two cover system field trials on the tailings dam and installation of a variety of field instruments to monitor the hydraulic performance of the test covers during all seasons of the year. Field performance monitoring commenced in April 2002 and will continue for a minimum of two wet-dry climate cycles (third phase), prior to using the field data for calibration and subsequent validation of numerical models developed for the cover system trials (fourth phase). This paper describes the work completed for the first two project phases and also discusses the initial performance of the cover system trials.

Jan 1, 2003

By Katsutoshi Inoue

Pectic acid gel crosslinked with epichlorohydrin was found to have very high selectivity to lead(II) and iron(III) ions over zinc(II) ion compared with commercial weakly cation exchange resins containing the same carboxylic functional groups, suitable for removing small amount of impurity metal ions from waste zinc plating solutions. In order to lower the cost, new adsorption gel was prepared from orange juice residue containing pectic acid by crosslinking with epichlorohydrin, which was also found to be suitable for removing these impurities. Further, very cheap adsorption gels was prepared not only from orange but also from apple juice residues by a simple method through just saponificating pectin substances contained in these residues into pectic acid by calcium hydroxide followed by water washing and drying. These adsorption gels exhibited excellent adsorption behaviors for removing the impurity metal ions away from zinc.

Jan 1, 2003

By J. Ipinza

The slime formation with several metallic impurities from acidic electrolytes of copper has been studied. On fresh Pb-Ca-Sn anode surface firstly the formation of PbSO4 takes place, then, it is transformed in the conducting PbO2, which covers the anode surface. It has been experimentally established the formation of a manganese dioxide double layer at the anode; this double layer was always composed of a thick external layer of non-adhering and easily removable scales, and of a thin internal layer, which adheres relatively well to the surface of the electrode. It was found that manganese dioxides present in the slime were of different nature: a non-adhering layer produced by electrolysis (-MnO2) on the PbO2 surface and a pure chemical precipitation in the solution (-MnO2). When iron is present in the electrolyte on this last layer of manganese, lead sulfate was found. In the case of arsenic and antimony in the electrolyte the slime generated was found to be lead sulfate and amorphous compounds of those ions. The lower slime generation in Chilean EW plants could be due to the lower contents of iron and manganese in the electrolytes. It was found that this slime formation rate not only is due to the electrolyte composition but also to the poor control of operational parameters at EW plants.

Jan 1, 2003

By Junji Shibata

Waste solution from the Ni non-electric plating process contains 4.0 kg/m3 Ni, 0.1 kglm3 Fe, 0.0 I kg/m3 Zn, 48 kg/m3 S042-, 98 kg/m3 HP032-and 31 kg/m3 laetic acid as a typical composition. Solvent extraction, cementation, ion exchange resin and precipitation methods are possible to use for the treatment of this kind of solution. In this study, solvent extraction of Ni was investigated using two kinds of extractants to clarify the relation between extraction percent and pH for various extractant mixtures. As Ni ion has an octahedral structure with ligands, the synergistic effect for Ni extraction is considered to take place in solvent extraction using two types of extractants. The investigation of the synergistic effect for Ni extraction was carried out in case of various extractant systems.

Jan 1, 2003

By Mitsutaka Hino

The contents of gangue minerals, such as A1203, P205, crystalline water and so forth in the iron ore imported to Japan tend to increase year by year, Though the increments of such gangue contents are approximately 0.1-0.2 mass%, some problems for the blast furnace operation in ironmaking process have already been reported, In order to clarify the mechanism of harmful effect caused by the small increment of gangue minerals, mainly A1203, on the blast furnace operation, the dripping behavior of FetO-CaO-SiO2-AI2O3-MgO slag from the iron funnel, which simulated the micro-porosity in sinter ore, has been observed with the wide range of basicity, Al2O3, FetO and Mgo contents. The effect of MgO on the dripping behavior of slag has been summarized in this paper, It was found that the addition of 2mass% MgO resulted in large increase of hold-up on the most of the conditions. When FetO content was less than 20mass% and the basicity was lower than 0.8, MgO lowered the hold-up even if the slag contained 10mass% Al2O3. Every slag hold-up showed the minimum at the basicity of less than unity on the conditions of constant FetO and A1203 contents. This trend became remarkable when the slag contained 2 mass% MgO.

Jan 1, 2003

This paper presents an initial investigation into the viability of co-kriging the grades of multiple mining cuts in a two dimensional, thin reef scenario. Deposits with gradational mineralized zones, in the perpendicular sense, are not as well served by the use of reef accumulation and thickness as deposits characterized by a sharp distinction between ore and waste rock. South African Bushveld Complex platinum deposits and Witwatersrand gold deposits are examples of this distinction. The calculation of an optimal mining cut is of paramount importance in the mining of Bushveld platinum. Two-dimensional kriging of a constant stoping width mining cut is an effective method for resource calculations once a cut is decided, but this begs the question of how to decide on the cut. Comparison of multiple cuts is used as a way of achieving this decision on many of Anglo Platinum’s operations. Although the kriging of each cut is valid in isolation, occasional negative values occur when incremental grades between overlapping cuts are calculated. Negative incremental grades cannot reflect reality. They are thought to be related to the inability of the method to include the strong continuity in the perpendicular direction demonstrated by the relevant variograms. Co-kriging of related variables has been investigated as a potential means tore impose this inherent order relationship. Various co-kriging options have been investigated. The method has been tested on a real data set from an established platinum operation. One of three types of anomaly has been investigated so far. The results show that co-kriging the mining cut grade as the primary variable, with just one secondary variable, the reef thickness, eliminates most occurrences. Severe anomalies remaining are arguably indicative of population mixing and might be more effectively treated by rezoning the data. Aim—To investigate the viability of co-kriging the grades of multiple mining cuts as a method for resolving anomalies in the estimation of such cuts on Bushveld platinum deposits, with applicability to other thin reef type deposits with a gradational not sharp cut-off between ore and waste in the direction perpendicular to the reef. Keywords: co-kriging, cross variograms, ordinary kriging, platinum, two-dimensional, grade profile

Jan 1, 2003

By Ramana G. Reddy

Thermodynamic modeling and experimental study on impurity capacities and their distribution between mattes or metal and slags in smelting, converting and refining of non-ferrous metals was discussed. A brief review on the recent developments in copper smelting and converting is presented. The analysis showed that, copper smelting capacity increased by a factor of 10 since 60's, smelting rate increased by a factor of more than 5 and process fuel equivalent decreased by a factor of 2. A thermodynamic model for prediction of impurities capacities in slags and their distribution in mattes and slags was developed. The impurities capacities (i.e. sulfur and arsenic) of slags were calculated a priori with no adjustable parameters using the Reddy-Blander model. The capacities predictions were made in a wide range of matte and slag compositions, Pso, and temperatures in conditions pertaining to copper and lead industrial slags. The calculated results for sulfide and arsenate capacities are in good agreement with the available experimental and industrial copper and lead industrial slags data. The sulfide and arsenate capacities in copper slags (fayalite, ferrite and olivine) and lead slags are reviewed. The application of RB model predicted ratios of 02 and S2 partial pressures in industrial copper smelting processes are discussed. Application of this model for the prediction of Sb, Bi and other impurity capacities and their distribution ratios in mattes or metal and slags, in industrial smelting and refining processes is discussed.

Jan 1, 2003

By B. Zlender

ABSTRACT: The paper presents investigation of carboniferous slates from the Trojane hilly area performed on series of samples of equal material. The results of static loading tests show that carboniferous slate is heterogeneous and yields on slate layers. Where that kind of heterogeneity is distinctive the strength results are essentially lower of commonly tests results. The results of dynamical loading tests show that the slate surfaces have the essential meaning for the stability of the material. When those surfaces are moistened the material become unstable. RÉSUMÉ: L'article présente une épreuve des ardoises carbonifères de la région montagneuse de Trojane sur une série des échantillons des matériaux identiques. Les résultats des tests de charge statique montrent que l'ardoise carbonifère est hétérogène et qu'elle cède sur les couches d'ardoise. Quand l'hétérogénéité est distinctive, les résultats de stabilité sont essentiellement plus bas que les résultats obtenus par des tests ordinaires. Les résultats des tests de charge cyclique montrent que les surfaces d'ardoise sont très importantes pour la stabilité du matériel. Quand ces surfaces sont mouillés, le matériel devient instabile. ZUSAMMENFASSUNG: Der Artikel präsentiert die Forschung von Karbonschiefersteinen im Bereich des Bergland Trojane, ausgeführt durch Serien von Proben aus den gleichen Erdmaterial. Die Resultate der statischen Belastungsprüfungen zeigen, das die Karbonschiefersteine heterogen sind und die Schieferflächen nachlassen. Wo bei dieser Art der Heterogenität die Festigkeitsergebnisse wesentlich niedriger sind als bei gewöhnlichen Testergebnissen. Die Ergebnisse der zyklischen Belastungsprüfungen zeigen das die Schieferflächen eine wesentliche Bedeutung für die Stabilität des Erdmaterials haben. Wen diese Schieferflächen befeuchtet sind, wird das Erdmaterial unstabil.

Jan 1, 2003

By A K. Bayer

When the human eye fails in the evaluation of quality parameters in the extraction of minerals the use of laser-induced fluorescence analysis (LIF) can supply more detailed information on the composition of rocks. On the basis of measurements of selected raw materials engineering concepts for the use of this method in the mining industry as an innovative system for horizon control of mining machines will be described and the most important analysis parameters, influencing factors and interference variables are presented.

Jan 1, 2003

By Rex E. Loesby

The marble deposits of Yule Creek were first discovered in the late1870s. Minor quarrying occurred between that discovery and the early 1900s. Major development occurred in 1905, when Channing Meek, with some help from the Rockefellers, raised $3 million to develop the Colorado Yule Marble Quarry. That is $50 million in today’s dollars. Some of the words used to describe the marble deposit were “gigantic, remarkable, flawless and immense.” Boosters proclaimed, “The marble age is here.” Obviously, dreams were big for Marble.

Jan 1, 2003

By F. T. Cawood

Inauguration of the new political dispensation in South Africa in 1994 initiated a dynamic shift in the ownership, management and development of the country’s affluent mineral heritage. The process of substituting the old South African regime with a new equitable system, started soon after the 1994 election of the African National Congress (ANC) to parliament. The Congress’ Freedom Charter revealed the intent of the new dispensation when it called for radical transformation of mineral development. However, since 1955 there have been important changes affecting the rules of mineral development. These are: •Firstly, a drastic change in politics ushered in by negotiation, a spirit of reconciliation and a desire to settle disputes peacefully •Secondly, the globalization of the South African mining industry in tandem with the opening of domestic mineral resources to foreign capitalists; and •Thirdly, the introduction of sustainable development as a holistic approach to mineral development in order to replace traditional narrow-minded environmental management. Each of these significantly shaped the new mineral investment environment of South Africa. This paper represents a summary of the historical developments leading to the current Mineral and Petroleum Resources Development Act No. 28 of 2002, its Regulations, the much-publicised Broad-Based Socio-Economic Empowerment Charter and its associated Scorecard.

Jan 1, 2003

By G W. Wilson, M Aubertin

A desulfurised tailings cover was installed at the Detour Lake Mine in Ontario, Canada, to reduce oxygen penetration into the underlying sulfidic tailings. The cover ranges from one to 1.5 m in thickness and was intended to maintain high water saturation to reduce oxygen diffusion and consume oxygen by oxidation of the residual sulfide minerals. The tailings impoundment was instrumented to measure climatic parameters, water levels and water content profiles within the tailings and single-layer cover. One year of monitoring data was collected. Additional tailings samples were obtained for geotechnical and geochemical characterisation. The average grain size of the cover material was found to be coarser than the underlying tailings. Monitoring also indicated that air entry values of the cover material were lower than the tailings. Numerical modelling was conducted on the cover to predict water content profiles under varying climate conditions together with the depth of oxygen penetration and diffusive oxygen fluxes. Estimates of the diffusion coefficient and kinetic oxidation rates from field data compared well with values obtained by laboratory measurements. Numerical simulations indicate water saturations of less than 85 per cent can be expected under varying climate conditions. Predicted oxygen flux rates through the desulfurised cover over tailings with high acid potential indicate low flux rates reaching these tailings due to either consumption of oxygen by residual sulfur within the cover or saturation of the underlying tailings.

Jan 1, 2003

By Karl J. C. Harries

13.1. RIGHT TO RECEIVE ROYALTY CONTRACTUAL ONLY1

Jan 1, 2003

By Seong-Jong Kim

The formation behavior and corrosion characteristics of anodic oxide films on pure Mg and Mg-AI alloys were investigated focusing on the effects of anodizing potential, Al content, temperature and NaOH concentration. Pure Mg and Mg-AI alloys were anodized for 10 min at 3, 10, 40, and 80 V in NaOH solutions. Mg(OH)2 was generated by an active dissolution reaction at the surface of the specimen and the product was affected by temperature while MgO generation increased with NaOH concentration. Moreover, the current density after anodizing for 10 min at a constant potential decreased with increasing AI content in Mg-AI alloys,

Jan 1, 2003

By J. A. Finch, T. Weber

"Bubble size in flotation is strongly influenced by frother concentration in the pulp liquor. There is no accepted method of judging the dosage and thus how effectively frother is being distributed to control bubble size is not known. This will hamper certain plant test work where constant bubble size (e.g., when comparing reagents) is implicit. Bubble size is not easy to measure in plant and gas holdup is suggested as a surrogate in the development of a proposed “meter” to estimate frother concentration. The meter is calibrated to enable frother concentration to be estimated on samples drawn from any location in the flotation circuit. The meter and its calibration are described.As general background the action of frothers in reducing bubble size by retarding coalescence is discussed and the bubble generation systems for which the effect will be important are considered.INTRODUCTIONBubble size is an important variable in flotation. The flotation rate constant k has been related to mean bubble size Db by k % Db -n with n ranging up to 2 (Ahmed and Jameson, 1989) and even 3 (Yoon, 1993). Recent work has introduced k % Sb, the bubble surface area flux, given by Sb = 6 Jg / Db (where Jg is the superficial gas velocity or volumetric gas rate per unit cell cross-sectional area), i.e., n = 1 (Gorain et al., 1998). Regardless of the exact value of n, the significance of bubble size in flotation remains. In many plant trials it will be implicit that bubble size has not changed and attention will focus on other process variables. The measurement of bubble size, or a surrogate, would be useful addition to any test work.The size of the bubbles is influenced by several variables, gas rate, gas injection system (e.g., impeller design and rotation speed in a mechanical cell) and pulp composition (chemicals added, percent solids), but the most important is frother concentration (Harris, 1976). The frother functions by retarding coalescence (see appendix), which acts to preserve the small bubbles generated in the pulp (and permits a stable froth to form on top of the pulp). The measurement of bubble size is thus related to measuring frother concentration. The distribution of frother and whether sufficient (to control bubble size) is reaching the intended parts of the circuit then become important considerations. At present there is no simple way to judge frother concentration in a plant. In this communication we introduce a possible methodology, a “frother concentration meter”."

Jan 1, 2003

By Ximing Yuan, Yongsheng Xu, Hongjie Li

A study of a static demolition agent that can be used underwater has been carried out. A new type of granulated static demolition agent with rapid reaction has been tested in several hundred experiments. It can be used conveniently and simply in the field. It demonstrates a fast reaction rate with high expansion pressures. The important characteristic of the new type of granulated static demolition agent is the ability to function underwater. It will destroy rock and the other brittle material without flyrock, vibration, shock wave, toxic gas or noise. The reaction rate can be controlled within 30-60 minutes. It is difficult to use these products when the reaction rate is less than 30 minutes and it is less efficient when the reaction rate is longer than 60 minutes. The reaction rate is slightly increased after the material is kept in storage for two years. A new type of the hydraulic device that is used to measure the expansion pressure of solid materials has been designed. The expansion pressure of the granulated static demolition agent has been tested with the device. It is shows that the expansion pressure of the granulated static demolition agent can get to 80~120MPa in 60 minutes. Also included is a discussion of the thermodynamics of the static demolition agent.

Jan 1, 2003

By K. J. Oliver, A. G. Meyers, S. P. Hunt

Deformation Rate Analysis (DRA) and porosimetry have been used to demonstrate the “stress memory” effect in rock and to estimate the vertical in-situ stress in samples of fine-coarse grained sandstone and carbonaceous mudstone. The results of this study indicate that the stresses predicted using both methods are similar to those determined from depth and density of the overburden rocks. The results confirmed that DRA was still applicable even when the core had been sampled 18 months prior to testing. Additionally, the DRA results were modelled using the software PFC2D. A uniaxial test was modelled using the same rock parameters as those observed for the actual core samples. This numerical technique can be used as an aid for DRA results analysis, and can also be used to predict the minimum stress level at which the DRA technique is applicable. The results confirm that any rock mechanics laboratory having standard test equipment could apply the DRA method combined with standard UCS testwork to determine the in-situ stress. Mit der Analyse der Deformationsrate (DRA) und der Anwendung der Porosimetrie wird der Spannungsgedaechtnisseffekts (Stress Memory Effect) im Fels demonstriert, und es werden Abschaetzungen fuer die vertikale in-situ Spannung einer Probe aus mittelgrobem Sandstein und carbonierten Lehmstein getroffen. Die Ergebnisse dieser Untersuchung zeigen, dass die mit Hilfe dieser beiden Methoden ermittelten Spannungen sind vergleichbar. Die Ergebnisse bestaetigen, dass DRA noch anwendbar ist, wenn die Proben schon 18 Monate vor Untersuchungsbeginn gesammelt worden sind. Darueber hinaus wurden die DRA Ergebnisse mit Hilfe des Sofwarepakets PFC modelliert. Ein einaxialer Test wurde mit genau die gleichen Felsparametern, die fuer die eigentliche Probe gelten, modelliert. Diese numerische Methode kann sowohl als eine Unterstuetzung fuer DRA Ergebnisanalyse als auch zur Ermittlung der minimalen Spannung, bei dem die DRA Methode noch anwendbar ist, herangezogen werden. Die Ergebnisse bestaetigen, dass jedes Felsmechaniklabor, das mit den ueblichen Testgeraeten ausgestattet ist, die DRA Methode in Kombination mit dem Standard UCS Testarbeit zur Bestimmung der in-situ Spannungen anwenden kann. L'Analyse du Taux de la difformité (DRA) et les porosimetry ont été utilisés démontrer le " effet de la mémoire " du stress dans roc et estimer le stress dans - situ vertical dans échantillons de grès du grained fin grossier et mudstone carbonifère. Les résultats de cette étude indiquent que les insistances ont prédit utiliser les deux methods est semblable à ceux déterminés de profondeur et densité du surchargez des rocs. Les résultats ont confirmé ce DRA était encore même applicable quand le coeur avait été goûté 18 mois avant tester. En outre, les résultats DRA étaient des modelled qui utilisent le logiciel PFC2D. Une épreuve de l'uniaxial était modelled qui utilise les mêmes paramètres du roc comme ceux observé pour les réels échantillons du coeur. Cette technique numérique peut être utilisée comme une aide pour DRA résulte analyse, et peut aussi être utilisé pour prédire le niveau du stress minimum à que la technique DRA est applicable. Les résultats confirment que tout laboratoire des mécaniques du roc qui a le matériel de l'épreuve standard pourrait appliquer la méthode DRA combinée avec testwork UCS standard pour déterminer le stress dans - situ.

Jan 1, 2003

By Jan J. Cilliers, Nicolas Barbian, Esther Ventura-Medina

"Froth structure and stability are known to play an important role in determining flotation recovery and selectivity. An industrial sampling campaign was performed to develop a clearer understanding of the effect of flotation variables on froth stability and the role played by the resulting stability on flotation performance.Froth stability was estimated as the fraction of bubbles bursting on the surface of the froth through image analysis and the solids loading on the bubbles at the top surface. It was generally found that high air flowrates resulted in a drop of froth stability showed by a drop in the fraction of air overflowing and a decrease in the solids loading and simultaneously produced low copper recoveries and low concentrate grades. Deep froths only allowed a small fraction of air to overflow and consequently produced low recoveries. An increase from a standard to high frother dosage did not result in a larger fraction of air overflowing, hence producing low recoveries. Likewise, low frother addition only allows low recoveries because the resulting unstable froth cannot support itself. Low aeration was found to be preferential as it allowed high particle loading, therefore high bubble stabilisation, and low gangue entrainment, resulting in the highest flotation performance.Additional laboratory tests were performed to introduce a new stability parameter and to give a clearer understanding of the effect of flotation variables on froth stability. The results confirmed some of the observations made on the plant."

Jan 1, 2003

By Toru H. Okabe

As part of a systematic study on the thermodynamic properties of complex nitrides, phase equilibria of the system Li-M-N (M Mg, AI, Ga) at 900 K were investigated. An attempt to determine the thermodynamic properties of complex nitrides was made by using the galvanic cell method, which utilizes LiMgN as an electrolyte under nitrogen atmosphere. The electromotive force (Emf) of ilie cell at temperatures between 800 and 1100 K was measured. Whilc the Emf of the cell at 900 K was measured to be 0.137 V, data discrepancies of ±0.03V were found. It was difficult to determine temperature dependence of ilie Emf. The Gibbs energy change for the reaction, 113 LbN (s) + 1/3 Mg3N2 (s) = LiMgN (s), at 900 K was determined to be tJ.Gor (LiMgN) -13.2 (±2.9) kJ/mol. Using thermodynamic information on ilie binary nitride from literature, the standard Gibbs energy of LiMgN was derived to be AGO f (LiMgN)= - 121 kJ at 900 K. The thermodynamic stability range of nitride was discussed by constructing isothermal chemical potential diagrams that provide a better understanding of ilie stability region of the LiMgN phase. The diagram was found to be in good agreement with the isoiliermal phase diagram determined by ilie alloy equilibration meiliod. Although the obtained data includes large uncertainties, the results provide a better understanding of the iliermodynamic stability of nitrides. The potential application of this complex nitride to nitrogen chemical sensors or a medium for controlling nitrogen potential is also shown.

Jan 1, 2003