Search Documents

By Bruce Cavender

Managers are frequently faced with the decision to perform a task or manufacture an object in-house or to hire an outside vendor to perform the function. Outsourcing decisions are usually driven by economics: work is outsourced if it can be completed at a lower cost or in a shorter time than it can in-house. A technique termed incremental analysis can be used to make this decision. Incremental analysis examines the financial impact of outsourcing decisions as a function of the firm's fixed and variable operating costs. To use this tool, individual components of production cost are identified as being either constant or varying with levels of production activity. The assignment of cost type can be made in several ways: though analysis of historical operating data, understanding of individual expense types, and so forth. Changes in fixed and variable costs resulting from each potential course of action are explicitly identified to project the financial outcome of each alternative. The alternative having the greatest positive impact on profit is selected for implementation. By using the fixed- and variable-cost framework, the analysis is conceptually straightforward and substantially simplified. Production managers can therefore use incremental analysis as a tool for fast economically beneficial decisions on a real-time basis.

Jan 1, 1999

By Rodney Clary

Building on work completed in earlier papers, the current paper presents a techno-economic evaluation of two recently demonstrated technologies for treatment of arsenic containing refractory gold concentrates. Using defined project parameters and inputs, the authors compare capital and operating cost estimates for pressure oxidation (POx), and the Albion Process™. The paper incorporates data now publicly available from the Albion Process™ plant, which has operated at the GeoProMining Gold (GPM Gold) project in Armenia since 2014, as well as recent POx circuits.

By Kalyani Das Sarkar

"Steel Authority of India Limited, a Public Sector Undertaking with a production capacity of 14 million tones of crude steel, is India's largest steel maker and ranks among the leading steel producers in the world. SAIL owns and operates eight manufacturing plant – five integrated steel plants at Bhilai, Durgapur, Rourkela, Bokaro and Burnpur producing carbon steel, and three speciality steel plants. All integrated steel plants have hospitals of 650 – 750 bed capacity with modern facilities to serve it's employees and adjoining localities in a clean and sustainable environment.According to the Bio-Medical Waste(Management and Handling) Rules, 1998 and as amended to date, all Bio-Medical waste which is generated during the diagnosis, treatment or immunization of human beings or in research activities pertaining thereto or in the production or testing of biologicals are to be categorized and taken to any facility wherein treatment, disposal of this waste or processes incidental to such treatment or disposal is carried out.The hospital management has created adequate treatment facility for Sharp and Infectious Waste, Pathological Waste and Anatomical Waste through Autoclave, Shredding Machine and developing deep burial pits. Some of these hospitals is ISO 9000-14000 certified. Use of above said treatment facilities in these hospitals are discussed in this paper.INTRODUCTIONBio-Medical waste means any waste, which is generated during diagnosis, treatment or immunization of human beings or animals or in research activities pertaining to these or in the production or testing of biologicals.Steel Authority of India Limited, a Public Sector Undertaking with a production capacity of 14 million tones of crude steel, is India's largest steel maker and ranks among the leading steel producers in the world. SAIL owns and operates eight manufacturing plant – five integrated steel plants at Bhilai, Durgapur, Rourkela, Bokaro and Burnpur producing carbon steel, and three speciality steel plants. All integrated steel plants have hospitals of 650 – 750 bed capacity with modern facilities to serve it's employees and adjoining localities in a clean and sustainable environment."

Jan 1, 2008

By Dan Michaelsen, Warwick Stewart

"PT Kaltim Prima Coal (KPC) is a large-scale truck and shovel operation mining thermal-coal in East Kalimantan, Indonesia. The operation produces 15 million tonnes of coal and mines over 120 million bank cubic metres of overburden annually. Approximately 35 percent of the waste rock is classified as potentially acid forming. Acid drainage must therefore be managed to prevent acid formation from spoil dumps and mined-out areas.KPC aims to prevent acid production in dumps by covering potentially acid forming spoils with materials identified as non acid-forming. The covers, built to engineering standards, minimise the flux of oxygen and water to pyritic spoils, thereby controlling the oxidation reaction, and reducing ARD discharge to negligible rates. Cover designs and cover materials vary according to stability, materials availability, equipment availability, and cost effectiveness. A modified field net acid generation (NAG) test procedure has been developed at KPC to identify and segregate overburden geochemical types. This paper discusses the ARD management strategies and operational procedures adopted by KPC to manage potentially acid forming waste rock. The development and field application of the NAG procedure at KPC is presented in a companion paper. Analytical"

Jan 1, 1999

By M. D. Strachan

Technical & Procurement Services Limited (TECHPRO) in Ashford, Kent, UK, have been appointed as Project Managers for the major rehabilitation of the Copper Smelting complex of Nkana Division, Zambia Consolidated Copper Mines Limited, (ZCCM) Zambia. In outline, the overall scope covers three main areas: a) Transfer and implementation of new technology into Zambia for the production of primary copper. b) Replacement of gas collection and gas treatment circuits to guarantee high quality feed to the acid plants. c) Completion of a number of minor projects in the copper smelter and associated utility plants to complement changes in the primary smelting technique. This paper describes the Project Management methodology and style used by TECHPRO to tackle typical problems that arise in retrofit projects of this type. Reference is made specific aspects of the smelter projects to illustrate solutions to the problems. The subjects. addressed highlight the complexities not only of having a -Client 5,000 miles from the Project Office, but also the difficulty of co-ordinating and controlling the performance of min sub-contractors who are also geographically distant.

Jan 1, 1991

By Ikuhiro Sumi

A new steelmaking process, in which manganese ore was intentionally reduced, was developed to achieve a higher manganese Yield using a combined blowing converter. In this study, manganese behavior was discussed through the introduction of a model. Apparent reduction rates of manganese were calculated by the two terms that were determined experimentally, with SOkg and 2S0ton combined blowing converters. The model calculated manganese changes during the operation. We applied the model to the actual operation and found that manganese behavior was predicted fairly well by this model.

Jan 1, 1996

By R. N. Reddy

The Pseudo capacitance of layered type Mn02 electrode material for electrochemical capacitors (EC's) was investigated. MnO2 was synthesized in our laboratory. Mn02 was prepared from heating of KMn04 at 300°C in air. Cyclic Voltammetry (CV) experiments were carried out using three electrode system, Saturated calomel electrode as reference electrode, platinum mesh as a counter electrode, and MnOz composite material mounted in a platinum mesh used as a working electrode. Two kinds of composite working electrode materials were used, one was mixture of MnOz and 25 wt% acetylene black, while the other was MnOz, 25 wt% acetylene black and 25 wt% carbon. All the experiments were carried out at 25OC. A maximum specific capacitance of 130 Fig and 118 Fig were observed at the scan rate of 2 mV/s and 20 mV/s respectively in 1M KC1 for composite electrode made with carbon. Results obtained in this study are compared with that of other electrode materials.

Jan 1, 2002

By Chu Yong Cheng

Manganese is one of the main impurities in the recovery of base metals from their ores. This is especially true when laterite ores are processed using the pressure acid leach (PAL) process. The use of intermediate precipitation, solids/liquid separation and re-leach in the three Western Australian nickel laterite plants to separate nickel and cobalt from manganese and other impurities makes these processes complicated and costly in capital and operation. The research work carried out by the solvent extraction (SX) group at the A J Parker Cooperative Research Centre for Hydrometallurgy (CSIRO Minerals) has led to the development of direct solvent extraction processes to separate nickel and cobalt from manganese and other impurities. The simplicity of the process flowsheets and the expected savings in capital and operating costs are the major advantages of the new direct solvent extraction processes over the existing processes. By using a new synergistic organic system, Versatic 10 / dccyl-4-pyridinccarboxylatc ester, with a pilot plant leach solution from BHP¬Billiton (after iron precipitation), the metal values (Ni and Co) together with zinc and copper were separated from manganese and other major impurities (Mg, Ca and Cl) in the first SX circuit. The co-extracted manganese, magnesium and calcium were easily scrubbed out. The extraction and stripping kinetics of the metals with the new synergistic organic system were very fast and the synergistic system was found to be chemically stable. pH-extraction isotherms of metals with D2EHPA showed that the extraction order as a function of pH50 was Zn2+ > Ca2+ > Mn2+ > Cu2+ > Co2+> Ni2+> Mg2+. Semi-continuous test work with a cobalt pilot plant leach solution from Peko Rehabilitation Project Pty Ltd and a synthetic solution to simulate a concentrated laterite leach solution from BHP-Billiton showed that manganese, together with calcium, copper and zinc can be separated from nickel, cobalt and magnesium. This led to the development of another direct solvent extraction process to separate manganese and other impurities from nickel and cobalt and to recover nickel and cobalt from leach solutions. A project was initiated by HiTec Energy Ltd to recover manganese from waste laterite leach solutions using SX technology and to further purify it to produce high purity electrolytic manganese dioxide (EMD) for the high quality alkaline battery industry. Batch tests were conducted to select a suitable organic system for the extraction of manganese in terms of selectivity and extraction and stripping kinetics. A total of eight organic systems were tested using waste laterite processing solutions. A Versatie 10 / synergist system showed very promising results. By using the synergistic system, high manganese recovery would be obtained, fewer SX stages would be required and a higher A:O ratio could be used in extraction, resulting in a smaller organic inventory and lower capital costs. The risk of gypsum formation is also minimised with the synergistic system. Keywords: Solvent Extraction, Manganese, Laterite, Synergist

Jan 1, 2004

By E. Charles Abbey

Manganese in electrolyte has both beneficial and detrimental effects in Zn electrowinning. Mn oxidizes to form MnO2 on Pb–Ag anodes, cell walls and pipes. MnO2 reduces anode corrosion but also leads to short circuiting and maintenance issues. MnO2 is thought to interact with chloride ions and produce oxidized chlorine species. The interactions between Mn and Cl are not well understood. Therefore, two sets of 45+ day bench scale experiments were conducted to investigate the effects of the manganese to chloride ratio on anode corrosion rate and electrolyte chemistry using rolled Pb–Ag anodes. Daily manganese and chloride losses from the electrolyte appeared to be correlated. Increasing the average Mn/Cl− ratio from ∼7:1 to ∼11:1 reduced the anode corrosion rate. Increasing the ratio above 11 did not reduce the corrosion rate further. Anode scales produced with Mn/Cl− ratios at and above 11:1 contained some γ–MnO2 while scales formed with ratios less than 11:1 did not.

By Zhouhua Jinag

The attempt has been made to manufacture high nitrogen austenitic stainless steels by pressurized electro-slag remelting furnace with maximum nitrogen pressure of 7MPa. To obtain high nitrogen content in steels, the compound electrodes with different nitrogen sources (FeCrN, Si3N4) were prepared. Using the Si3N4 as the nitrogen alloying source, the silicon contents in ingots were prone to be out of the specification range, and the electric current fluctuated greatly and the surface qualities of the ingots were poor. The surface qualities of the ingots were improved using FeCrN as nitrogen alloying source. The sound and compact macrostructure ingot with the maximum nitrogen above 1.0wt% could be obtained. A series of high nitrogen austenitic stainless steels have been successfully developed by this method. The mechanical and pitting corrosion resistance properties of high nitrogen austenitic stainless steels were investigated. The results show that the steels exhibit excellent mechanical and pitting corrosion resistance properties.

Jan 1, 2009

By S. Sugiyama, M. Kiuchi

"New metal working processes, such as the mashy-state mixing, mashy-state forging, mashy-state rolling and mashy-state extrusion are developed and applied to manufacture the so-called particle reinforced metals, fiber reinforced metals, particle reinforced cladding metals and so forth. These metal-ceramics composites are made of metal sheets, metal powders, ceramics particles and ceramics fibers. The mashy-state processes are also used to work those composites into bars, wires, tubes, plates, sheets, machine parts and other products. The working conditions necessary to manufacture sound composite products are clarified and the mechanical properties of the products are investigated. Through the investigation, it becomes clear that the mashy-state processes are useful and effective to manufacture metal-ceramics composites. It is al so known that these processes may be applied in various ways to development of new metal matrix compounds. IntroductionThe so-called metal-ceramics composites and processes to manufacture them are now being widely investigated in order to comply with increasing demands for new materials with novel and excellent mechanical properties and functions. The metal-ceramics composites are expected to have superior characteristics with respect to the elastic modulus, hardness, anti-wear resistance, high temperature strength and other mechanical properties to those of conventional metallic materials.The present authors ha v e been investigating into new metal working processes which are based upon the characteristics of metals and their alloys in the mashy-state. In the mashy-state, the metal (or alloy) includes both of the solid and liquid components. According to the fact that the partial melting takes place and the liquid component usually exists at grain boundaries, the metal in the mashy-state has quite different mechanical properties from those of the metal in the solid-state. Because of that the bonding force among grains is very weak due to the partial melting occurred at grain boundaries, the mashy metal has distinctively low flow-stress and high deformability. The mashy metal splits into grains or particles and sticks to others very easily. It is so soft as to be stirred up just like a lump of sherbet, but it is sufficiently viscous to be mixed up with other materials, such as ceramics particles and ceramics short-cut fibers."

Jan 1, 1988

By H. Roberts, C. Hassall

The opening years of the new millennium will be characterised by the closure of many lead and zinc mines because of reserve depletion. However, weak commodity prices through the second half of the 1990s have slowed project evaluation and have made it difficult to raise finances for the development of new mines required to replace lost output and to meet increasing demand for metal in the future. Growth of lead and zinc demand will be determined by the pace of global economic activity, especially in the emerging economies. How rapidly demand grows will have a key bearing on the possible shortfall in mine output and the response of prices to the implied tightening of metal supplies early in the new millennium. These issues are the focus of a discussion of the critical lead and zinc supply developments which will unfold post 2000, taking into account project lead times and the role that recycled metal plays in meeting market demand.

Jan 1, 2000

By Paul Dewison

For nine years, from mid-1987 to mid-1996, the copper market enjoyed what appeared to be an endless boom in which prices were much higher relative to production costs than for most other base metals. After the boom ended abruptly mid-1997 with the Sumitomo affair, copper was burdened by an overhang of new projects that promised to swamp demand in what, with the Asian financial and economic crisis of 1997, had become a considerably worse consumption environment. Now, demand prospects do not look so bad. If, as we suspect, we will be dealing with a more rational market in the future, it becomes all the more important to forecast accurately the prospects for consumption. In this paper, we present a new methodology for copper demand forecasting. The methodology forms the backbone of the demand-side analysis for the multi-client study entitled "Long Tenn Outlook for Copper", co-authored by Metalica Ltd. and Bloomsbury Minerals Economics (BME). Key components of the methodology are as follows. (1) Relate demand to economic structure. (2) Focus on products rather than refined consumption. (3) Apply a consistent products/applications analysis to all countries and time series. (4) Incorporate scrap market dynamics within the analytical framework.

Jan 1, 1999

By V. L. Stolyarova

The high-temperature Knudsen effusion method was used to study partial pressures of vapour species, activities of components and the Gibbs free energies in the DyF3-Dy2O3 system at the temperature (1357±5) K. Partial pressures of vapour species were obtained by the ion current comparison method, with the DyF3 partial vapour pressure over pure DyF3 as a standard. The equilibrium constant of the gaseous reaction DyF3 + DyOF = Dy2OF4 is evaluated. Thermodynamic data obtained are in a agreement with the available phase diagram of the DyF3-Dy2O3 system. Results of the present study illustrate the negative deviations from the ideal behaviour in the system.

Jan 1, 1997

By Kumar M. Lyer

The channel reactor for ferrous and nonferrous processing has been modeled as a combination of ideal reactors. Cold model studies simulated the counter-current flow of slag and matte (or metal) with high-strength submerged gas injection. A composite model has been developed which describes the mass transfer between the two liquid phases, including the transfer of minor elements. The residence time for the matte droplets in the matte/slag emulsion is compared with the settling rates for the matte droplets in the slag to determine their relative importance in the mass transfer between matte and slag. The governing equations for mass transfer have been developed using correlations for the mass-transfer coefficients in the continuous and dispersed phases. An application of this scheme to a typical copper smelting system is presented.

Jan 1, 1993

By K. H. Bech, S. T. Johansen

"The mass transfer at fluid-fluid interfaces due to turbulent agitation is investigated theoretically. In particular a theory is derived for interface stresses due to interface energy and surface renewal. This theory indicates that surface renewal may take place if the geometry is sufficiently large and if surface tension is sufficiently low.By using a model for a typical turbulent structure we compute the interface mass transfer for a stressless interface and a fully interface. Results for the general situation is not presently available. The computed results are used to derive analytical expressions for the mass transfer based on turbulent kinetic energy and free stream turbulent length scales.One important application of the theory is the mass transfer at the electrolyte side of the bath-metal interface in the Hall-Heroult process. For this process we show that mass transfer should be expected to be of the rigid surface type."

Jan 1, 1999

By G. S. Gupta

To predict the iron oxide concentration a mass transfer model has been developed for an Induction Smelting Process (ISP) in which self-fluxed composite pellets (made of iron ore, brown coal and lime) are melted in a single phase induction furnace in conjunction with top blown oxygen. Transient mass balance equation with complex boundary conditions has been worked out by adopting a relatively new approach known as the cell model approach. These equations have been solved numerically using finite difference technique to obtain the iron oxide concentration profile in the ISP. Numerical and experimental results obtained for iron oxide concentration show a reasonable agreement with each other.

Jan 1, 1991

By A. Kar

A mathematical model is presented for pure titaqium deposition from titanium tetrabromide on a stainless-steel (SS 304) substrate. Five three-dimensional, transient, and nonlinear partial differential equations are used to account for the diffusion of various species inside the deposition chamber and the thermal decomposition of titanium tetrabromide, titanium dibromide, and titanium monobromide at the surface of the substrate in order to determine the thickness of the titanium film deposited on the substrate. The effects of various process parameters on the deposition and shape of titanium films are examined, and under certain conditions, the deposited titanium films are found to have volcanic profiles.

Jan 1, 1992

By Dan Adams

A number of gas-liquid processes require high intensity agitation systems to provide uniform blending and dispersion of reactants in order to achieve desired end products. Processes such as hydrogenation, fermentation, and minerals processing have used conventional down pumping or radial agitation systems with some success. In 1996, LIGHTNIN introduced the concept of Up-Pumping to the industrial marketplace as an improved mixing technology for these applications. For processes requiring gas-liquid mass transfer, such as those listed above, conventional mixing technology requires the use of gas introduction devices (sparges) below impellers. These devices can be a maintenance concern due to plugging and erosion in the presence of solids. Up-Pumping impeller systems are able to draw in a significant amount of gas from the headspace, much more so than conventional vortexing impellers designed for headspace gas incorporation. This paper will demonstrate the effectiveness of Up-Pumping impeller systems that have the potential to eliminate need for sparge devices entirely. It demonstrates the ability of Up-Pumpers to re-entrain gas for higher utilization compared with conventional impeller technology. This is significant in applications using costly gases such as enriched oxygen or hydrogen, reducing overall operating costs of production.

Jan 1, 2003

By G. Roderick Eggert

Material criticality reflects the degree to which a raw material is both necessary and subject to supply-chain risks. This study compares the criticality of selected raw materials from the differing perspectives of the manufacturing sectors of China, the European Union, Japan and the United States.