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By T. K. Dichmann, J. A. Finch

"Microflotation, laboratory batch, and in-plant minicell continuous tests were conducted to determine if copper ions not only activate sphalerite but also depress pyrite when the minerals are together. Microflotation tests showed that pyrite recovery increased with addition of copper ions in the pH range of 5-10 when alone, but decreased when sphalerite was also present. Batch flotation tests (Red Dog ore) showed that upon addition of copper, pyrite recovery decreased significantly. The continuous tests (Louvicourt Mine) confirmed this and indicated that with excess copper pyrite recovery can increase. The results suggest there is competition for copper and xanthate in favour of sphalerite. To take advantage of this competition it may be necessary to control the sequence and rate of copper, collector, and lime addition. INTRODUCTIONFlotation, in common with all physical separations, is an imperfect process that results in misplacement of minerals. One source of this imperfection is accidental activation by contaminating metal ions. An important practical example is the misplacement of pyrite to zinc concentrates. Flotation of sphalerite generally requires activation by copper ions, added as copper sulphate. Copper ions are also used to activate pyrite [l] hence there is the suspicion that accidental activation contributes to the recovery of pyrite (Py) with the sphalerite (Sp). However, recent literature has shown that copper ions may make Py less floatable if Sp is also present. Xu et al. [2] conducted continuous minicell tests in-plant at Kidd Creek Operations (division of Falconbridge Ltd.) and showed that while the addition of copper sulphate improved zinc/iron selectivity, it did so as much by reducing the recovery of pyrite as increasing zinc recovery (Figure 1)."

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 Ken Mills

This paper describes the first successful use of hydraulic fracturing to induce caving events "on demand" in Australia. Moonee Colliery operate a longwall immediately below a thick conglomerate strata. This strata temporarily bridges across the extracted longwall panel to create a large area of standing goal' When this standing goat' eventually collapses, the windblast generated presents a significant hazard to men working on and around the longwall face. Hydraulic Fracturing has been successfully introduced to take control of the timing of these caving events so as to eliminate the risk of windblast injury, The longwall face area is completely evacuated during the treatment. Water is pumped into an injection point located in the conglomerate strata above the standing goat. A horizontal fracture is generated and grows outward from the in point, separating the conglomerate strata below the fracture horizon_ At some point the strata can no longer span and a goat fall is initiated. After a treatment, mining can be recommenced with the windblast hazard eliminated.

Jan 1, 2000

By Toshia Suzuki, Keiji Kakudate, Yoshihiro Adachi

"A macro model for the steel usage pattern in Japan is proposed. The steels are classified into four types; converter steel for machinery and for construction and electric furnace (EF) steel for machinery and for construction. The steels are assumed to be discharged from the society in accordance with lifetime distributions of each usage. The amount of EF steel and the accumulation in society are calculated using a population balance model. The comparison with the calculated results and statistics ensures the validity of the model. Since the amount of EF steel for construction will increase and be oversupplied, EF steel will have to be used for machinery. The required and available amounts to supply EF steel for machinery are considered from the point of allowable· copper concentration for machinery use. Copper contaminates steel used for machinery during recycling process and contamination ratio is evaluated with the model. Copper concentration in EF steel is predicted for various scenarios.IntroductionThe amount of CO2 emission from Japanese steel industry is 48.0 million C-ton in 1990 and it occupies 15.1% of the total amount in Japan. In order to reduce the C02 emission and to save the natural resources, it is strongly required to promote the recycling of steel. However, the impurity contaminates steel in recycling process and lowers its quality. The copper concentration in EF steel is analyzed by Toi et al. using a macro model with the assumption that steel is discharged in proportion to the accumulation amount [1]. However the discharged amount of products is dependent on their age for service and usage pattern and not on the accumulation amount. In addition, the degree of copper contamination is different depending on the usage of steel. Therefore a precise model that contains the age for service within the society as a parameter and distinguishes the usage· of steel is necessary in order to clarify the problems in the recycling of steel."

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

Since first introduced, the coal mine roof rating (CMRR) has been widely accepted as a tool for geologic characterization and mine planning. This paper discusses the application of the CMRR to another practical ground-control problem: extended cuts. Extended cuts, i.e., cuts greater than 6 m (20 ft) in length, are commonly used with remote-control continuous miners. Extended cuts can greatly increase productivity, but they have been associated with a number of fatal roof-falls. When extended cuts are attempted in weak roof material, the roof may collapse before it can be bolted Until now, it has not been possible to predict where conditions may not be suitable for extended cuts. In this study, data on the CMRR and extended-cut experience were collected at 36 mines in seven of the United States. It was found that, when the CMRR was greater than 56, deep cuts were routine in nearly every case. When the CMRR was less than 37, extended cuts were almost never taken, and, when the CMRR was between 38 and 56, extended cuts were sometimes, but not always, feasible. The data also show that extended cuts are less likely to be stable if either the entry span or the depth of cover increases.

Jan 1, 2000

By A. V. Tarasov, V. M. Paretsky

"The design is based on the thermal processing of the wastes in· the intensively bubbled melt in the Vanyukov furnace at the relatively high temperatures (1350- 1450 °C), In this case: -the secondary wastes are not formed; - the especially toxic substances at the outlet from the furnace are absent. The technology was tested on a large scale (on semicommersial bases). Technical and economical basis show profitability of recovery complex for processing of hard garbage waste (HGW) using this technology: the period of capital, investments refunding for the, recovery, complex construction with process annual capacity of 240 thousands tons of wastes is 1,5-2,5 years,"

Jan 1, 2000

By Yoshinao Kobayashi

he removal of oxygen from titanium and zirconium is important for use in application because it significantly affects the mechanical and physical properties such as ductility and toughness. However, thermodynamic properties of oxygen in molten titanium and zirconium have not been clarified and the effective deoxidation process of molten titanium and zirconium has not been established. In this study, the standard Gibbs energy of reaction of oxygen and yttrium in molten titanium and zirconium have been measured by a chemical equilibrium technique. Molten titanium, zirconium, and their alloys with aluminum were equilibrated with a Y2O3, A12O3, or Zr02 pellet in a cold crucible. The results are summarized as follows:

Jan 1, 2000

The economic viability of many Southern African massive mining operations is threatened by excessive dilution. In many operations currently in progress, some stopes are experiencing as much as 115 per cent waste ingress reporting to drawpoints. This paper examines the magnitude, causes and types of dilution and presents a set of general principles for the control of dilution in massive stoping operations.

Jan 1, 2000

By J. Ouellet

"ABSTRACTA brief background on in-situ testing of mine backfill, as well as pressuremeter testing is briefly described, and results from an in-situ testing on paste backfill are presented. A series of self-boring pressuremeter tests were done from the top of a backfilled stope in an underground mine. The tests were conducted along a 20-metre vertical line in the centre of the stope. Some 14 tests were performed along this depth. The instrument used was a Camkometer built by Cam Insitu, Cambridge. The instrument proved to be efficient and reliable for underground testing in a cemented paste backfill. The testing program was conducted within the planned schedule with a high success rate. The test done in this study permitted the measurement of paste backfill strength, stiffness and in-situ horizontal stress within the backfill. RésuméUn bref historique des essais in situ dans le remblai minier est présenté. L’essai pressiométrique est décrit succinctement et des résultats d’une campagne d’essai dans un remblai en pâte sont présentés. Un programme d’essais au pressiomètre auto-foreur a été réalisé à partir du sommet d’un chantier remblayé sous terre. Les essais ont été réalisés le long d’un ligne vertical d’environ 20 mètres pour un total de 14 mesures. Le Camkometer de la firme Cam Insitu de Cambridge a été utilisé. Cet instrument s’est avéré efficace et fiable pour tester le remblai en pâte cimenté sous terre. Le programme d’essai s’est déroulé à l’intérieur de l’échéancier prévu avec un taux de réussite élevé. Ces essais ont permis de déterminer la résistance, la rigidité de ce remblai ainsi que les pressions in-situ prévalant dans le remblai."

Jan 1, 2000

By Renato G. Bautista

"The development of processing methods for the preparation .of three electronic materials with rare-earth components is discussed. The resulting processing innovations are the results of a search for an economically competitive pilot scale or industrial production flowsheet without compromising the required properties of the final products. The three cases highlighted in this presentation are: 1) The preparation of high energy (Pr-Nd-Ce)FeB magnets for MRI application from a mixed-rare-earth oxide with a narrow range of composition directly prepared from the solvent extraction circuit of bastnaesite ore. 2) The kg production of the giant magnetocaloric effect Gds(SixGe1-x)4 magnetic refrigerant materials from commercial grade gadolinium metal (95 to 98 at. % pure) instead of high purity gadolinium metal (99.8 at. %); and 3). An industrial chemical synthesis flowsheet for the production of the superconductor precursor of YBa2Cu3O7.INTRODUCTIONIn the laboratory discovery stage, the synthesis of a new material is carried out using very high purity components, usually the highest purity available. As the new material is studied and characterized, the effectiveness of its desirable properties becomes better defined and understood. The evaluation of the effectiveness of the .property over the range of a given parameter and other interactions are further studied. Once it's potential application becomes clear, a practical and economical processing method need to be developed. The successful material processing flow sheet does not necessarily have to be a scale up of the laboratory procedure. At this stage, substitution of starting components and with lower purity materials is considered as the economics of the processing becomes a major issue. In addition, other approach to it's synthesis"

Jan 1, 2000

By M. J. Scoble, H. L. Francis, D. F. Salter, G. R. Baiden

Intelligent ore delineation refers to the ability reliably to characterize the geological setting of a mineralized body and its grade distribution. This necessitates using all available geological information in a timely and efficient manner, such that effective geological control is achieved. The importance of geological control is paramount to improving the efficiency and competitiveness of underground mines. As a result, the development of new geosensing tools designed to provide more reliable and timely information should be a priority. However, as the sensing tools advance then so, too, must the decision support system in order to allow the full benefits of these tools to be achieved. One potential system considered able to provide this architecture is ’true 3D-GIS’ (Geographical Information System). GIS promises to provide a seamless data flow and to connect information currently unavailable to the underground mine operations by bringing together previously disparate and spatial data sets in a visually effective and timely way. This paper considers the potential revolution GIS offers over the flow and use of data in mining by focusing on the integration of geosensing data and GIS to facilitate intelligent ore delineation.

Jan 1, 2000

By J. A. Rodgers, K. C. Whitaker

The time domain during which an explosive detonates and causes rock to fragment and displace is on the order of tens of milliseconds. Because of this, the dynamic processes that occur during this time frame often become a source of confusion when trying to analyze the performance of explosive products in decked blast designs. As an illustration, the authors have experimentally examined explosives malfunction in decked blasts through state-of-the-art measurement techniques. The interaction of explosive products and blast geometry was examined in detail using the analysis of a series of decked blastholes. Explosive and initiator malfunction in decked blasts is often considered to be entirely the result of insufficient inert decking material, however, it is shown that rock properties and dynamic burden conditions may have a significant impact on decking performance. The successful application of deck-blasting technique for control of ground vibration amplitude relies on an understanding of the true dynamic performance of the blasthole.

Jan 1, 2000

By R G. Jeffrey

The Northparkes, Endeavour 26 orebody is a porphyry copperûgold deposit and comprises a moderately to well jointed rock mass characterised by gypsum veining, the intensity of which decreases with depth. The top 480 metres of the orebody is currently being mined by block caving, the undercut dimensions measuring 196 metres in length by 180 metres in width. Continuous caving was never achieved after the completion of the undercut thus cave inducement techniques were sought to maintain caving so as to safely sustain production. The use of hydraulic fracturing as a cave inducement tool was successfully trialled in December 1997 using existing exploration boreholes located midway up the current lift. Subsequent fracturing campaigns have enjoyed various degrees of success and have yielded in excess of seven million tonnes of ore at a significantly lower cost than conventional cave inducement techniques. Monitoring of both the hydraulic fracture system and the rock mass response has provided considerable insight into the geometry, growth and influence of hydraulic fracture networks above the Northparkes block cave, and has initiated additional research into the use of hydraulic fracturing in other mining methods.

Jan 1, 2000

By Jingbo Liu, Zhimin Wang, Wenchao Li

"IntroductionThe advantages of non-stoichiometric perovskite material are highlighted in many papers[l]and many of this family of materials are well-suited to integration into microsensor devices. Among them, barium titanate is the most promising due to it's piezoelectric, pyroelectric, dielectric properties. Through modification, BaTiO3-based materials can be utilized in many kinds fields, such as surface wave probe; pholoconducting devices, field-effect transistor, permanent memory permanent storage, and ultrasonic transducerl2-3l. In this Paper, a series of BaTiO3-based polycrystals were synthesized by sol-gel processing which appears to be a very promising method for the manufacture of ceramic, because it offers significant advantages such as high purity, chemical homogeneity, controlled particle sizes of ceramics, and lower processing temperatures [4]. In a sol-gel process, alkoxides of the constituent elements show different reactivity toward water so that the preparation of multi-component homogenous system is difficult. In the experiment, inorganic salt was substituted for some of the alkoxides. Acetic acid which is employed for the solvent and catalyst, acts as donor ligand to titanium alkoxide and controls, the hydrolysis polycondensation reaction. Taking these aspects into consideration, we select the system Ba(OAc)2, , La(OAc)3, Ti(O11Bu)4 and acetic acid which is used as both solvent and homogeneous catalyst for the first time.ExperimentalA series of La3+-doped BaTiO3-based nano-crystals were prepared with sol-gel technology using various parameters. The precursor solution was prepared in the presence of barium acetate, lathanium acetate, and titanium tetrabutoxide monomer in butyl alcohol. According to the flow chart (fig. I.), Ba(OAc)2, La(OAch dissolved in the glacial acetic acid (0. lmol/40ml) in a three-neck flask were mixed with a solution of titanium tetrabutoxide monomer in butyl-alcohol(l 7ml/20ml) at room temperature and under constantly, vigorous stirring conditions. In most cases, the resultant solution was golden yellow and stable in the air. To this precursor solution, containing Ba, La, Ti in the desired ratio, water was added incrementally for hydrolysis under continuous stirring until sol was formed. After aging for more than 2 hours, sol was transformed to gel at room temperature. If heated during aging, the gel was formed in a shorter time. The wet gel was allowed to dry at 50°C for more than 10 hours. The dried gel was transparent or light yellow. In order to obtain BaTiO3-based nano-crystals, the amorphous dry gel was calcined at 600°C, 700°C, 800°C, 900°C, 1000°C respectively[5]. The ceramic humidity sensor was formed through the cold-pressed, aged, capsulated routes. The dried gels were crushed in an agate mortar and then pressed into discs of ? 1.5 X l.5mm (l.5mm diameter and l.5mm thickness), then held at about 16.5 MPa pressure for 3 min [6]. The disc was sintered at 1350°C and 1400°C for I hour respectively. During the processing, an Ag-Pt electrode was inserted in the sensor [7]. (See the flow chart.)"

Jan 1, 2000

By R A. Medower

This paper provides a glimpse into the future of minerals processing with emphasis on æAutomation InnovationsÆ for the new millennium, particularly those involving advanced process control and innovative new applications of process control technology in 2007.

Jan 1, 2000

By Edward J. McNamara

People in the real estate industry are fond of saying that the three most important features of a piece of property are, in order, location, location, and location. This is perhaps the reason that the owners of a well known high-end restaurant chain chose to spend $15 million dollars to renovate 5000 square feet of basement in a 22-story commercial building in the heart of New York City's Time Square. The goal was to create a music club with a stage area and dance floor with a mezzanine level surrounding the dance floor. In order to create the 50' x 40' dance floor and 20' x 40' stage area, 3 concrete columns were removed. New transfer girders were used to transfer the loads of these columns to new steel columns. For the mezzanine, nine columns had to be underpinned. All work continued while the restaurants, shops and offices above carried on business as usual. This paper details some of the means and methods utilized as well as the challenges faced by Underpinning & Foundation Constructors, Inc. in underpinning the columns and installing the new transfer steel.

Jan 1, 2000

By Dajian Wang

To obtain the thermodynamic properties of a multicomponent liquid alloy system over the whole range of concentration at an arbitrary temperature, the free volume cell theory has been applied to derive the formula of activity coefficients of liquid solutions based on the infinitely dilute solutions at some temperature. The linear logarithmic relationship between activity coefficients of binary dilute solutions and reciprocal of absolute temperature have been verified, and are in good agreement with the experimental values from the literature. The Monte-Carlo algorithm was used to calculate the nonlinear end value equations of binary systems, then the free volume parameters obtained were correlated with the activity coefficients of liquid binary, ternary, and quaternary systems at an arbitrary temperature. Three dimensional a-X-T diagrams of some binary systems representing the temperature and concentration dependence of activities were plotted. The calculated results regarding non-ferrous alloy systems have been statistically examined with the experimental values from the literature. Hence, this simple approach could be useful for analyzing thermodynamic properties of liquid alloy systems.

Jan 1, 2000

By S Dirdjosuwondo, R Plaisance, L Thoma

PT Freeport Indonesia, a subsidiary of New Orleans-based Freeport McMoran Copper and Gold of New Orleans, operates a large mining complex on the Western half of the Island of New Guinea in Tembagapura, Irian Jaya, Indonesia. The IOZ (Intermediate Ore Zone) mine, one of the underground orebodies, is mined by block caving. The area affected by the cave collects a large quantity of rain and ground waters mixing with fine rock particles. The mixture, commonly called æwet muckÆ, sometimes spills into drawpoints and makes the working environment hazardous to the loader operators. Wet muck is observed in an increasing number of drawpoints in the IOZ mine and remote LHD (Load-Haul-Dump) technology has been implemented to handle the ore. The driving force for this automation project has been the safety of the loader operators. The system has been developed mainly in-house and incorporates state-of-the-art features. Up to eight remote loaders and nine rock breakers are controlled from an underground control room located approximately 400 metres from the active extraction panels. The two underground crushers and nine conveyor feeders are also operated remotely from an adjacent control room. The development of FreeportÆs remote system has taken time and considerable effort. Not only the success of the IOZ mine was at stake but also the fulfillment of environmental commitments pertaining to the mill tailings. Approximately eight per cent of the mill feed must come from underground skarn deposits to neutralise the acid-generating tailings generated by the huge Grasberg open pit ores.

Jan 1, 2000

By L. F. Ruppert, W. D. Watson, S. J. Tewalt, L. J. Bragg

The U.S. Geological Survey recently completed a digital coal resource assessment model of the Upper Pennsylvanian Pittsburgh coal bed which indicates that of the original 34 billion short tons [31 billion tonnes] of coal, 16 billion short tons [14 billion tonnes] remain after subtracting mined-out coal. When technical, environmental, and social restrictions are applied to the remaining Pittsburgh coal model, only12 billion short tons [11 billion tonnes] are available for mining. Our assessment models estimate that up to 0.61 billion short tons [0.55 billion tonnes], 2.7billion short tons [2.4 billion tonnes], and 8.5 billion short tons [7.7 billion tonnes] could be available for surface mining, continuous mining, and longwall mining, respectively. This analysis is an example of a second-generation regional coal availability study designed to model recoverability characteristics for all the major coal beds in the U.S.

Jan 1, 2000