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By Hector Henao

To provide thermodynamic data for converting the nickel matte to liquid nickel, an experimental study was conducted in the phase equilibrium between the Ni-S alloy and the CaO-Ah03 based slag melted in a MgO crucible at 1873 K under controlled Pso2 of 10.1 kPa and pO;, in a range between 2.5x,IO,2 and 10.1 Pa by using CO-C02-S0Z gas mixtures. The content of nickel in the slag at POz of 10.1 Pa, above which solid NiO is expected to precipitate in the equilibrium state, was found to be 4.1 mass% and the contents of sulfur and oxygen in the nickel melt were 0.4 and 0.2 mass%, respectively. It was clarified that increase in the temperature reduces the solubility of nickel in the slag and the contents of sulfur and oxygen in the alloy. The distribution of minor elements such as gold, silver, copper, cobalt, iron, arsenic and antimony between the Ni-S alloy and the CaO-AI20) based slag was also studied. The distribution ratios of iron and cobalt, defined by (%X in slag)/[%X in alloy] where X is the minor element, are larger values than that of nickel, while those of copper, silver and antimony are similar to that of nickel. The distribution ratios of arsenic and gold are lower than that of nickel in the higher range of oxygen partial' pressure.

Jan 1, 2003

By J. Huisman

With the introduction of ever-stricter environmental operating guidelines, capital expenditure restrictions and operational budget cutbacks, the biological method of SO2 removal becomes more and more attractive. Biological treatment of dilute flue gases is a more cost effective technology in comparison to conventional sodium hydroxide scrubbing. Although the investment costs for sodium hydroxide scrubbing is lower, the operational costs are significantly higher. In addition, the end product of the biological installation is sulfur instead of sodium sulfate; and no further wastewater treatment of the bleed from the biological installation is required since heavy metals are removed simultaneously. Another option for the treatment of SO2 containing gas at a sulfuric acid plant is the production of extra sulfuric acid of the discharged SO2 by applying an additional converter. Comparing biological treatment with this option shows much lower investment costs for the biological installation. Sulfur is produced which can be converted to sulfuric acid, so the bio-route will be more cost-effective than an additional converter. In principle, the biotechnological gas cleaning system is an integration of an absorber with a wastewater treatment facility. In the absorber, the SO2 containing gas is brought into contact with the washing water. The effluent absorber liquid contains a mixture of sulfite and sulfate that is converted into elemental sulfur. This conversion takes place in an integrated system; first, the sulfite/sulfate mixture is converted anaerobically into sulfide; secondly, the sulfide is converted aerobically into elemental sulfur. Subsequently the sulfur is separated and the water is returned to the absorber. Due to the buffer capacity of the washing water, removal efficiencies over 98% are possible. In addition to SO2 removal, it is possible to convert for example other bleeds streams such as scrubber acid or weak acid to sulfur in the same SO2 installation. Recent evaluations concluded that biological desulphurization of flue gases is not only economically attractive in comparison to convention sodium hydroxide scrubbing but also in comparison to gypsum producing systems and even seawater scrubbers. This paper describes the technological and economical viability of biological flue gas desulphurization.

Jan 1, 2005

By Mônica Suede Santos Silva

This work describes characterization of the performance of the tundish of a six strand continuous casting unit of the Companhia Siderurgica Belgo Mineira, Joao Monlevade, Brazil using physical modeling. Permanent and transient conditions, due to ladle metal composition changes are considered. Pulse and step tracer addition techniques are employed to assess the control variables. For transient conditions the degree of inter-mixing and the minimum residence time are determined with a view to optimize the process especially during the grade changes of steel.

Jan 1, 2003

By L. L. Tavlarides, N. V. Deorkar

"Recovery/Recycling of metal ions from industrial process waste streams is a preferred alternative to disposal by conventional techniques. This paper presents methods for preparation of inorganic chemically active adsorbents to be used in fixed bed adsorbers. Methods for immobilization of chelating agents on the inorganic supports are discussed. The prepared adsorbents are characterized to determine coverage density of functional groups, effect of pH on metal ion removal efficiency, regeneration efficiency and uptake capacity. Results from the laboratory scale and bench scale experiments are presented here.IntroductionRemoval of heavy metal ions from processing wastes in various industries is an important problem. Waste streams in electroplating, electronic, catalyst preparation and hydrometallurgical industries contain metal ions such as copper, nickel, chromium, lead, tin, cadmium, silver, gold and platinum. One major concern for the non-ferrous metal industry is secondary recovery of precious metals and cyanide from cyanide leachate from smelter residue and hydrometallurgical waste streams.Recovery methods recently considered include evaporation, electrolyte metal recovery, reverse osmosis (1), adsorption, ion exchange (2,3), membrane separation (4,5) and Solvent extraction. These processes have met with various levels of limited success. The use of liquid ion exchange molecules to selectively extract metal ions for on-site treatment of these waste streams is currently receiving substantial interest (6,7). This interest seems from an awareness of the advances made in the development of commercial extractants for metal ion separation in hydrometallurgical industries (8). However, separation by solvent extraction processes is generally considered to be economical in the range of aqueous metal ion concentrations from 0.01 to 1.0 mol/lit (9). In order to exploit the selectivity of chelating agents, the idea of immobilizing chelating agent into a solid matrix has attracted growing attention in recent years. Many supports such as inorganic oxides, organic polymers, cellulose powder and polyurethane foam can be used for immobilization of chelating agents. Over the last decade, considerable efforts have been directed toward attachment/introduction of chelating agents into a polymer matrix (10,11). Inorganic supports as compared to polymer supports provide high mechanical strength, chemical and thermal stability, and high reaction rates due to open pore structure. On the contrary, organic resins shrink and swell, thus affecting mass transfer (12). Many of the disadvantages of polymer supports can be excluded by the use of inorganic supports. Innovative use of immobilization techniques can produce inorganic chemically active adsorbents with comparable capacity, stability and reaction rates. Consequently, the objective of our program is the development of inorganic chemically active adsorbents to be used in a fixed-bed unit operation as an alternative heavy metal ion recovery process. Methods of preparation of inorganic chemically active adsorbents, (ICAAs) characterization and applications are discussed in this paper. A brief summary of the results from laboratory scale studies and bench scale studies is presented."

Jan 1, 1996

By Joseph C. Milbourne

Tetra Technologies CCIX? (continuous countercurrent ion exchange) system has been involved in a wide range of uranium concentration, separation and purification applications over the past 40 years. Uranium ion exchange applications have ranged from the treatment of copper heap leach solution containing 5 parts per million of uranium to the treatment of high strength sulfuric acid solutions containing several thousand parts per million of uranium. The flexibility and the countercurrent mode of operation and other unique features of the CCIX? have resulted in successful uranium recovery from these solutions and many others.

Jan 1, 1995

By Zeng Zheng, Liu Chen, Yu Xing-Fu, Tian Su-Gui, Zhang Chao

"Single crystal nickel-base superalloy is prepared by using the various withdrawing rates. By measuring creep properties and microstructure observation, the influence of the element segregation on creep properties of the superalloys is investigated. Results show that the dendrite spacing and the segregation extent of the elements decrease with the enhancing withdrawing rate. The superalloy with smaller dendrite spacing has lower segregation of the elements and better creep resistance. The dislocations climbing over the rafted y’ phase is thought to be the deformation mechanism of the alloy during steady state creep. In the later stage of creep, the fact that some dislocations shear into the rafted y’ phase may twist the rafted y’ phase. As the creep goes on, the initiation and propagation of the cracks occur up to occurring creep fracture, which is thought to be the fracture mechanism of the superalloy during creep.1. IntroductionSingle crystal nickel-based superalloys consist of high volume fraction of ?? strengthening phase and ? matrix, and possess the excellent high-temperature mechanical and creep properties, therefore, they have become the main material to make the blades of the advanced aeroengines[1-3]. Some literatures report that the temperature-bearing and creep-resistance properties of the single crystal nickel-based superalloys can be remarkably improved as the increases content of the refractory elements, such as W and Re[4-6]."

Jan 1, 2012

By J. F. White

An experimental study was undertaken to evaluate the feasibility of a selective chloridizing roasting pre?treatment process for the elimination of impurities from zinc feed?stocks prior to recovering zinc by conventional unit operations. In this investigation, a number of chemistries that might serve as a basis for such a pre? treatment process were examined. A variety of chloridizing agents were admixed with EAF dust to promote the selective removal of lead and cadmium by the formation of volatile metal chlorides, he results of the experimentation firmly establish that selective chloridizing roasting is a technically feasible means of eliminating lead and cadmium from EAF dust. Excellent extraction efficiencies were accomplished with a number of chloride additives; as high as 98 percent lead extraction and 88 percent cadmium extraction were attained with minimal zinc losses, Continuous pilot?scale tests reinforced the trends established by laboratory?scale experimentation, Attempts of chlorine elimination using pyrohydrolysis were less successful. The extent of chlorine elimination was found to be highly dependent upon EAF dust sample type and treatment temperature.

Jan 1, 1996

By Zhou Jun

Water-quenched samples were taken from a commercial flash furnace at three levels along its reaction shaft during operation at high feed rate. The samples were subjected to a series of analysis and observation. Such processes of the feed in reaction shaft as oxidation, desulfurization, melting, slag and matte formation and etc., variations of particle size along axial and radical direction of the shaft are investigated. The following smelting mechanism in reaction shaft named as “Multi-particle and multi-phase fusion model” is proposed: (1) Fragmentation and collision of concentrate particles take place simultaneously in reaction shaft with particle size growing up. Collision produces large-size “unit melt” which falls into the reaction layer in the settler bath. (2) In the settler reaction layer below the shaft, weak bath smelting reactions take place among the shaft products, producing final matte and slag which separate into two layers. (3) The processes in the shaft are all progressive along the whole height of the shaft. The predominant reaction in the shaft is oxidation, not reduction.

By Cajsa Samuelsson, Theo Lehner

Converting and refining play a central role in the extraction of metals. Sweden has a long tradition as an experimental play ground for metallurgists, chemists and alchemists, developing new methods and technologies. Presenters of papers are usually happy in recording successful developments. But reporting failures can be as great a value as the former. In the paper experiments and experience in process development are illustrated, differences between ferrous and non-ferrous developments are highlighted and industrial learning curves are discussed. 53

Jan 1, 2009

By J. A. Bakken

Thermal plasmas are interesting for a wide range of metallurgical and chemical processing applications. The 300 kW experimental reactor PRESS, which has been in use since 1987, is operated in the transferred arc mode with three or one plasma torches . Tests include remelting of silicon fines and production of ultrafine silica. Work on a novel three stage process for production of silicon metal is under way. A 1:1 model of the plasma reactor is used to measure the wall heat flux distribution calorimetrically. The cold walls of this model are divided into several water-cooled sections. The same plasma torches as in the real hot-wall reactor are used. In parallel to the experiments and calorimetric measurements theoretical work is done on numerical modelling of one and three transferred arcs. A modified version of the flow simulation program FLUENT from Creare Ltd. is used.

Jan 1, 1991

By Nural Kuyucak

Acid mine drainage (AMD) occurs at operating and abandoned mine sites as a result of oxidation of sulphide minerals, and is characterized by low pH and heavy metal contamination (e.g. Fe, Zn, Cu, Cd, Al, Mn). It usually requires treatment before release in order to meet regulatory requirements. Chemical methods, such as lime neutralization and sulphide precipitation, are commonly used to treat AMD. However, the conventional processes require high capital and operating costs, and constant attention for many years into the future. In addition, the amount of sludge produced by conventional lime treatment processes poses an increasingly significant disposal problems at decommissioned mining operations. There is, therefore, an urgent need to develop passive, cost-effective processes for mitigating AMD and seepages originating from tailings and waste rock areas. Noranda Technology Centre (NTC) has been evaluating various methods being developed by other institutions, and exploring new ideas, to achieve passive in situ processes for treating AMD. These methods include anoxic limestone (ALS), lime-organic mixture (LOM), biosorbents (BIOS) and biotrench (BT). Current investigations at NTC involve preliminary bench-scale testing. Based on the outcome of the bench tests, a field test will be performed at a selected site. Details of the bench tests are discussed in the paper. Key Words: Acid mine drainage, treatment, metals removal, passive treatment, anoxic lime, limestone, biological treatment, sulphate reducing bacteria, biosorption, biosorbent

Jan 1, 1993

By M. C. Ruiz

In the present study, the size distribution, Fo(v), of organic drops produced in a continuous-mixing vessel has been determined experimentally for various conditions. The organic phase used was a 1: 1 mixture of a salicylaldoxime (LIX 860N-IC) and a ketoxime (LIX 64-IC) in an aliphatic diluent (Escaid 103). The aqueous phase was a copper sulfate solution. The results indicated that an increase in stirring speed, extractant concentration, and pH produced smaller drops. The effect of the stirring speed was the most significant, decreasing the average volume of drops by 57 % for a change from 300 to 400 rpm. On the contrary, an increase in the dispersed phase fraction, copper sulfate concentration, and retention time produced larger drops. Changes in temperature from 23 to 30°C did not affect significantly the drop sizes. In all cases, the experimental drop size distributions could be accurately represented by a lognormal distribution.

Jan 1, 2001

By A. Warczok

The heat transfer coefficient between liquid slags and solid surfaces is important for the design and operation of metallurgical reactors. An experimental technique developed for the purpose of measuring the heat transfer coefficient between liquid slags and solid metals is described. During the initial heating up of a Ni cylinder upon immersion in a liquid slag, a layer of frozen slag initially forms, then melts. The heat transfer coefficient measured during the initial rapid heat-up of the Ni cylinder, is approximately twice as high as the heat transfer coefficient measured during the final heat-up of the Ni cylinder subsequent of the liquidus temperature of the slag. The technique was tested in various melts i) NaNO3, ii) NaCl, iii) Na3AlF6 and iv) 2FeO*SiO2, giving consistent results. It was found that the heat transfer coefficient increases with increasing bath superheat and stirring. The heat transfer coefficient during the heating up following complete remelting of the frozen slag, is related to the slag superheat(AT) and the specific stirring energy(W) per kg of slag(E) as follows.

Jan 1, 1993

By Frank Mucciardi, Hujun Zhao, Pietro Navarra

"A heat pipe is a device having a very high effective thermal conductivity in which two-phase flow and heat transfer takes place. Recent research at McGill University has led to a new type of heat pipe that contains a flow modifier. This improvement has enabled the device to operate at the high heat fluxes encountered in the metallurgical industry.This paper summarizes the progress made to describe the fluid flow in the evaporator section of a McGill heat pipe with the goal of understanding how the flow modifier configuration is linked to the film boiling and dry-out limitations. A separated flow model, an instability analysis, a lift-off model and an energy balance model are used to calculate the theoretical CHF with varying flow modifier configurations and operation conditions. A summary of the current work to relate the flow modifier to the dry-out limitation is also given.Determining how the flow modifier affects both the film boiling and dry-out limitation will give insight into improving the flow modifier design so as to extend the operational range of McGill heat pipes in terms of maximum heat flux and heat load capabilities.IntroductionThe McGill heat pipe is a specialized two-phase heat exchanger developed for several metallurgical applications where temperatures and heat fluxes are typically close to or beyond the maximum safe range of conventional cooling technology.Over the last few years, several breakthroughs have brought this device beyond the proof-of concept stage and a series of industrial trials have been performed with success. These trials include two oxygen injection applications for the ferrous and non-ferrous industry [l], and two light metals permanent-mould casting applications [2,3]. Current projects include a blast furnace copper taphole cooling application [4], a copper smelting application and a thermal analysis probe application."

Jan 1, 2004

By S. Abe

Various copper anodes to be electrorefined were subjected to a heat treatment comprising annealing at a temperature in the range of 700 °c to 1,000 °c followed by a slow cooling preferably on the order of about 150 °c, and using these heat treated anodes , a series of dissolution experiments were conducted under conventional electrorefining conditions. The results obtained have indicated that the above annealing/slow cooling process dramatically improves the dissolution activity regardless of the type of anodes. As an example, passivation times of l to 3 minutes in a standard test have been increased to more than 80 minutes by this innovated heat treatment. Other advantages sterning from the improved anodic activity include reduced electrical short circuiting which results in substantial labor effort in the tankhouse, reduced energy requirement, and reduced cost of processing anode slimes because the amount of anode slimes is reduced. In addition, this process gives rise to a dramatic change in the nature of anode slime layer formed in such a way that a comparable final cathode copper product can be achieved even from high-impurity copper starting material.

Jan 1, 1987

By Åke Saudström

An EAF dust sample generated in a scrap based steel mill was treated by a combination of hydro- and pyrometallurgial techniques. The EAF dust contained mainly ferritic spinels forming solid solution phases according to the general chemical formula (MnxZnyFe1-x-y)Fe2O4 and other oxide phases such as ZuO. CaO and Ca2Fe2O5. The EAF dust was first treated by hydrochloric acid leaching at p8=3 which dissolved 63% of the zinc. The pyrometallurgical treatment of the leaching residue was studied using an induction heating system to simulate some important operations of EAF smelting of the residue in combination with steelmaking. The leaching residue was mixed with carbon powder to obtain a mixture with 52.1% ZnFe2O4 and 175% carbon. The mixture, scrap, and slag former were charged together in a crucible and heated to attain a melt temperature around 1650°C. The effects of different amounts of mixture on the zinc balance and iron recovery were examined. Based on the test results, suggestions are made for the EAF recycling procedure of the leaching residue.

Jan 1, 2003

By R. A. Roberti

Most copper refineries use conventional wheel systems to cast anodes. over a period of time the copper moulds that are used become warped and cracks develop. To control mould warpage, the mould's are either rejected after a certain warpage is reached, or the shape is restored by mechanical means. The cracks, unless they are very severe, are repaired by a peening process. Even with regular maintenance to control warpage and cracks, the moulds have a limited useful life. If warpage and cracks are not controlled, anode quality deteriorates and tankhouse operations are seriously affected. -An intensive study was initiated to develop means of controlling mould warpage which culminated in the d?evelopment of technology to control mould warpage to within ±1. 5 mm, and at the same time effectively contr0l: cracking and significantly increase the mould life-. The warpage control has been achieved by using a unique mould design. Mould cavities are present on both sides of the mould and periodic inverting controls the wa-rpage in the cavities. The mould casting procedure has been developed and all production wheels have been converted to the new mould design. The performance characteristics of these moulds will be detailed. 21

Jan 1, 1987

By Scott R. Giese, Lucas Dix

"Recently, there is a growing trend in the aluminum foundry industry to develop· improved melting and casting processes to produce lightweight, high-strength, and thin-wall castings for the aerospace and transportation industry. One casting method that has demonstrated industrial potential for producing clean, thinwall castings is vacuum-assisted, counter gravity casting. This process has the benefit of expeditiously and quiescently filling the casting cavity with a dramatic reduction of furnace related and reoxidation inclusions. Additionally, lower casting temperatures can be utilized because the application of vacuum during filling overcomes the resistive internal cavity pressure resulting in a finer, as-cast microstructure. The paper explores and discusses the processing and design conditions in improving the mechanical properties of A206 casting alloy using the vacuum assisted, counter gravity casting process.IntroductionThe process of metal casting has been, over the centuries, the chief production technique for components used in everyday life. However, the casting process has certain inherent problems that can adversely effect the properties of a finished product. These problems are directly attributable to the gravity pouring technique used to transfer molten metal to the mold and to fill the mold cavity.A recent study for the American Metalcasting Consortium demonstrated reoxidation products created during the casting process are five times more likely to cause product rejects than entrapped molding aggregates, melt slag, or furnace lining materials1. Formation of nonmetallic and intennetallic compounds are more prevalent in aluminum and titanium alloys because of their reactiveness to furnace lining materials and their high affinity for oxygen. The incorporation of undesirable compounds can be attributed to four areas of the casting operation. The sources are charge materials, melting technique, pouring methodology, and casting cavity filling. Aluminum foundry men have addressed the first three areas by selecting high quality melt stock, non-stirring melting equipment, and the use of porous ceramic filters. Unfortunately, little consideration is given to the last, but yet tl.1e most important part of the casting operation, the actual fill mg of the casting cavity.The generation of inclusion defects during the casting process can be described by two methods. As the liquid metal flows in the gating network and casting cavity, abrupt changes in flow d1rect10n cause the metal to become agitated. This mechanism liquid metal splashing, is generated by instability of the advancing liquid metal interface from turbulence effects as schematically illustrated in figure 1a2 . The surface oxide film bursts under high velocity conditions, folds over, and becomes dispersed and incorporated in the bulk liquid. Additionally, fragmented liquid droplets ejected from the disturbed interface oxidize and become dispersed in the metal stream."

Jan 1, 2000

By H. Eccles

BNFL, an internationally acclaimed company noted for its nuclear fuel cycle services and waste management technologies, collaborated with Viridian BioProcessing Ltd, a small company acknowledged for developing environmental biological processes, and an internationally recognised professor of biological sciences, to develop an unique bioremediation process for treating toxic, heavy metal contaminated land. This paper describes the process, with particular reference to the problem and scope of land contamination with toxic, heavy metals and the current available technologies. The process technologies are based on using indigenous, soil micro-organisms which can be stimulated to produce acid or sulphide ions to mobilise or precipitate the heavy metals respectively. Laboratory studies have indicated metal removal efficiencies of greater than 90 % can be achieved, whilst recovery efficiencies from the metal loaded leachate are even higher at approximately 95%.

Jan 1, 1996

By Charles H. Buclmam

"Environmental regulatory requirements for discharge of solutions and closure of operations for the gold mineral processing industry have been gradually lowered and in certain instances have been targeted to USEP A inorganic drinking water standards for dissolved ions in solution. The use of jar tests for water treatment process development is suitable for preliminary scoping work to be conducted in the research laboratory, as well as for optimization studies at the site of the treatment requirement. This paper will describe experimental methods which were performed using standard jar test equipment in efforts to produce solutions which meet USEP A inorganic drinking water standards after chemical treatment of cyanide solutions. The materials tested included gold bearing pregnant solutions from heap leaching operations, gold plant barren solutions from the Merrill-Crowe zinc cementation gold recovery process and gold heap leach wash solutions after carbon-in-column gold recovery. Experiments included cyanide destruction with sodium hypochlorite and arsenic and selenium co-precipitation coupled with mercury precipitation.IntroductionCyanide leaching solutions are used to selectively dissolve metallic gold from commercially viable mineral deposits. The heap leaching process involves stacking of gold bearing ores on specially designed solution containment pads and percolating alkaline cyanide solutions through the ore to dissolve the gold. Pregnant solutions containing the dissolved gold are collected and sent through a gold recovery process. After selective recovery of the gold, the barren solutions are recycled to the gold extraction process after adjustment of the solution alkalinity and available cyanide concentrations."

Jan 1, 1997