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By Michael J. McGuire

Rostoker, Inc. has developed a process to smelt solid hazardous/non-hazardous inorganic wastes. Near seven hundred experiments were performed. Actual industrial wastes as well as reagent grade chemicals were used. By mixing a multiplicity of these wastes to proper formulations, then furnacing them, it was determined that saleable end products could be reclaimed; metal, fume and slag. The slag, due to its siliceous structure was tested to be leach resistant (40 CFR). This formed the essence of our patent, #5,180,421 "Method and Apparatus for Recovering Useful Products from Waste Streams". What is unique is that a HTMR (High Temperature Metal Recovery) process has been developed that can treat a multiplicity of wastes within the same furnace. The discussion will include a list of waste streams we have treated, details of proper waste formulation and experimental results.

Jan 1, 1994

By SIMON TIMBILLAH

The chalcopyrite-molybdenite (Cu-Mo) flotation industry is increasingly turning to organic depressants as suitable replacements for inorganic reagents, such as NaHS, due to environmental and safety concerns as well as high consumption rates of the inorganic reagents. This presents an opportunity for improvements or design and synthesis of alternative reagents. Disodium carboxymethyl trithiocarbonate (Orfom® D8) depressant is an organic depressant with a carboxylate group on one end and a trithiocarbonate group at the other end. Fundamental results are shown regarding the interaction of the Orfom® D8 depressant in the bulk flotation of a Cu-Mo concentrate from an operating North American mine. Cyclic Voltammetry on pure copper and Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS) measurements on pure chalcopyrite with Orfom® D8 depressant treatment are also reported. Through such characterization techniques a potential adsorption mechanism of Orfom® D8 on the mineral surface was identified and its depressant characteristics in the Cu-Mo flotation systems explained.

By K. J. Murphy, A. R. Smith, A. P. Odorski

"The need for large quantities of oxygen for use in metallurgical processes was a major driving force in the commercialization of tonnage air separation plants. Oxygen, nitrogen and argon impact the quality, energy efficiency and environmental aspects of metals production. Cryogenic air separation processes have been used to supply most industrial requirements, however, newer technologies are available or under development to meet the needs of today's and tomorrow's metallurgical processes. This paper reviews the technical features and state of development of adsorption, chemical, cryogenic and membrane technologies. The technologies are compared in terms of plant size, oxygen purity and pressure, nitrogen and argon co-production, product use pattern and back-up requirements. Computer control systems are described that optimize operation over varying load patterns and ambient conditions; substantially lowering energy consumption. IntroductionOxygen production totalled 390 billion cubic feet in 1987. Although current production is lower than the peak of 455 billion cubic feet reached in 1979, oxygen remains the fifth leading chemical product manufactured in the u.s. (1) Metals manufacturing and fabrication accounts for sixty percent of the oxygen consumed in the u.s. Oxygen use in the steel industry consists of air enrichment for conversion of iron ore, purification of the iron in basic oxygen or other furnaces, and for cutting and welding the finished steel product. Nonferrous ores are smelted in oxygen enriched atmospheres to reduce energy consumption and increase capture of sulfur compounds to meet environmental requirements. In the future oxygen usage is expected to become even more important in metals production as energy costs increase, environmental standards become more stringent, and as new coal based processes become commercialized. Oxygen usage per ton of metal in the new direct reduction processes can be up to ten times higher than traditional steel making."

Jan 1, 1988

Pyrometallmurgical reactors constitute a key processing component in the total primary and secondary resource cycle, being involved both in primary smelting, converting and extraction, as well as the reprocessing of scrap, from aluminum cans to end-of-life automobiles. To effectively control the overall resource cycle, one needs to take a systems modeling approach of the whole cycle, seeking to also understand the dynamic process behavior of the individual components of the cycle, and then especially the part that contributes most to the chemical conversion, namely the pyrometallurgical reactor. This paper highlights the role of pyrometallurgical thermodynamics, in the whole resource cycle and specifically places equilibrium thermochemistry in the context of process dynamics where large variable inventories are recycled or maintained within the system. This paper will therefore review the semi-empirical dynamic modeling tools, which are used to model complex systems with the specific goal of developing dynamic predictive models, which also include slag-alloy chemistry, towards controlling the recycling in a feed forward manner. To illustrate the primary processing side, high carbon ferrochrome will be presented as a brief case study. It also will show how the distributed nature of the chemistry of melts in the case of primary extraction, and secondary materials such as recycled end-of-life vehicles, have a significant impact on the process outcomes and model predictions. It is therefore argued that the fundamental thermodynamics and kinetics in metallurgical reactors playa final crucial role in modeling the closed material cycle, but only when it is used in conjunction with process systems theory based on reconciled data for parameter estimation and model calibration.

Jan 1, 2003

Pyrometallurgical reactors constitute a key processing component in the total primary and secondary resource cycle, being involved both in primary smelting, converting and extraction, as well as the reprocessing of scrap, from aluminum cans to end-of-life automobiles. To effectively control the overall resource cycle, one needs to take a systems modeling approach of the whole cycle, seeking to also understand the dynamic process behavior of the individual components of the cycle, and then especially the part that contributes most to the chemical conversion, namely the pyrometallurgical reactor. This paper highlights the role of pyrometallurgical thermodynamics, in the whole resource cycle and specifically places equilibrium thermochemistry in the context of process dynamics where large variable inventories are recycled or maintained within the system. This paper will therefore review the semi-empirical dynamic modeling tools, which are used to model complex systems with the specific goal of developing dynamic predictive models, which also include slag-alloy chemistry, towards controlling the recycling in a feed forward manner. To illustrate the primary processing side, high carbon ferrochrome will be presented as a brief case study. It also will show how the distributed nature of the chemistry of melts in the case of primary extraction, and secondary materials such as recycled end-of-Iife vehicles, have a significant impact on the process outcomes and model predictions. It is therefore argued that the fundamental thermodynamics and kinetics in metallurgical reactors playa final crucial role in modeling the closed material cycle, but only when it is used in conjunction with process systems theory based on reconciled data for parameter estimation and model calibration.

Jan 1, 2003

By S. q. Honingh, G. Van Weert

Currently produced zinc-enriched blast furnace dust is stored on site at CORUS IJmuiden. To end this practise, a research program was started in 1996. Four technologies were studied: oxidative autoclave leaching in a chloride medium, fluid bed pyrohydrochloridisation (pyrohydrolysis) to yield lead-zinc-free (hematite) calcine, EAF (plasma) smelting/zinc fuming, and incorporation of the dust in 'iron foundry cupola charges. All aim to remove zinc and lead, recycle the iron residue internally, and produce a saleable zinc-lead product.

Jan 1, 2000

By Filippos Patsiogiannis

Laboratory size (5 kg) aluminum killed low carbon steel melts were desulfurized with synthetic fluxes in zirconia crucibles. The sulfur, oxygen, aluminum, silicon, and manganese contents in the melt were determined as a function of refining time and temperature. With a good argon shield and synthetic flux cover, melt reoxidation was not observed. Sulfur removal followed first order reaction kinetics. The effectiveness of calcia saturated calcium-aluminate (12CaO.7Al2O3) based fluxes in desulfurizing the steel melts was evaluated. The effects of initial sulfur level of the melt, weight of the flux (slag), and additions of tellurium, fluorspar, and barium oxide to the melt on the kinetics of desulfurization were also studied.

Jan 1, 1993

By Gopalakrishna M. Rao

"Several industrial and government laboratories are of the opinion that solar--cell technology will grow into a billion-dollar industry by the year 2000, especially if oil prices rise again. Of the variety of materials that have been investigated as the major component of photovoltaic systems, silicon appears to have an outstanding advantage. The cost factor is the primary importance in photovoltaic development, since the technology to make silicon cells of acceptable efficiency and life time has existed since the early stage of the space program. Electrometallurgy is one of the low--cost processes for the production of silicon, since it allows direct, single-stage production from some abundant, inexpensive source materials such as silica and fluorosilicates. Among several systems, two are given particular attention, using inorganic baths with Si0 2 or K2SiF6 as the source of silicon respectively. They appear capable of development to commercial production. Conceptual designs of a commercial--scale cell for silicon production at temperatures above its melting point, and of a pilot' plant for plating silicon from an all-fluoride bath are presented. Energy ProspectsThe major changes in the world energy since the first energy crisis in 1970 have impacted on our community. When oil was $40 a barrel in the mid-1970s, we became obsessed with the energy conservation and a search for alternate energies. Even though the crude oil fell below $15 a barrel during the last several years, our energy security fears continue to haunt us. This time it is not the scarcity, but the abundance of foreign oil and the decline in the domestic production.The prospects of energy depends on the demand and supply of energy. These, in turn, depend on future energy prices, which are linked to economic factors, political events, and unforeseen circumstances. Although no one can predict the future with certainty, three energy consumption patterns used by the Ford Foundation are as shown in Fig. 1."

Jan 1, 1988

By Achilles J. B. Dutra, Carlos M. Juarez

"The use of thiourea as a gold leaching reagent has been extensively studied by many researchers, and it has proved to be promising for some cases as refractory ores. Otherwise, the recovery of gold from these solutions did not receive so much attention. In this paper the electrowinning of gold in acidic thiourea solutions was studied by voltarnmetry and chronopotentiometry. An adsorption step was detected prior to Au(I) reduction and the diffusion coefficients at 25°C for Au-TU complex and FD were found to be 1.00 x 10.5 cm2 S-I and 1.98 x 10-5 cm2 S-I respectively. At -0.350 V (SCE) a passivation probably due to TU adsorption was observed. For higher overpotentials hydrogen evolution was the main reaction.IntroductionThe use of acidic thiourea solutions for the extraction of gold and silver has shown to be a promising alternative to the traditional process of cyanidation, specially for certain refractory ores (1-3) and electronic scrap (4). In some cases, the industrial scale was reached (1,5). The thiourea leaching of precious metals presents advantages over cyanidation, as faster kinetics, lower toxicity and lower sensibility to base metals; however the costs due to high thiourea consumption impairs its use.The majority of the publications on thiourea processing of gold is on leaching. Many are review papers (5-7). Recently, the adsorption and desorption of the gold-thiourea complex on activated carbon and ion exchange resins have been studied (8-11).Little research has been done on the electrowinning of gold from acidic thiourea solutions, most of it has been carried on the seventies and beginning of the eighties in the former USSR (12-17) and concerned the eletrolytic extraction of gold in tridimensional cathode cells.The present paper concerns the cathodic behavior of the gold-thiourea complex in the presence of formamidine disulfide in order to provide information on the electrowinning of gold from solutions obtained directly from leaching or from an elution process."

Jan 1, 1997

By N. A. Warner

Fundamental studies on the reaction of limestone or dolomite at high temperature with S02 are extended to the realm of large scale primary copper smelting. Whereas flue gas desulfurisation in the electric power utility industry is concerned with S02 concentrations normally less than 0.5 percent, high temperature smelting gases can have S02 levels approaching 100 percent. The reaction involved is very exothermic so proposals are made in this paper for returning the heat generated in sulfur fixation directly back to the copper smelting process. This integration leads to metal production with lower energy requirements than current technology. The anhydrite reaction product can either be disposed of locally with minimum adverse environmental impact or upgraded to a value-added product. It is assumed, of course, that no viable market exists to support sulfuric acid production.

Jan 1, 1996

A novel, low-pressure adaptation of Praxair?s coherent jet technology utilizing CoJet lances was developed for application at Inco&apos;s Copper Cliff Smelter where oxygen is available in large tonnage quantities but only at relatively low supply pressures (< 193 kPa header pressure). The project objectives were to evaluate the effect of coherent jet technology on controlling oxygen lance accretion (?horn?) formation and to increase oxygen efficiency in the Inco Oxygen Top-Blowing Nitrogen Bottom Stirring (TBBS) MK Reactor used for converting nickel- contaminated chalcocite to semi-blister copper. This paper describes the development and subsequent implementation and testing of two CoJet lances in this application.

Jan 1, 2005

By Ronald Erdmann

Today the BOF filter dusts and sludges are mainly dumped due to their zinc contents. By typically ranging from 2 to 5 % they prevent the filter dusts and sludges from beeing recycled via the blast furnace route. Based on the different discharge kinetics of Iron and zinc during the main blowing period In a bottom stirred BOF a simple and efficient system for recovery allow zinc fractions has been developed. The obtained material Is suitable for recycling without nsc of shell formation In the blast furnace. Different subsequent development steps have been performed. By starling with a very simple lime dependent model the sludge from the BOF off gas cleaning system was collected in two different sludge channel systems. This model based an the fact that most of the scrap based zinc Is discharged from the melt within the first eight to ten minutes of the BOF process. To Improve the system a spectroscope zinc sensor was Installed at the hot section of the off gas cleaning system to get more reliable informations on the actual zinc concentation of the BOF dust. By use of the system up to 50 % of the BOF sludge can be recycled.

Jan 1, 1995

By Grégory Miette

The paper deals with a process that allows the recycling in a cupola of EAF dusts with 18 % Zn. It produces dusts with zinc grade higher than 50 - 55 % and commercial cast iron with less than 200 ppm Zn, 50 ppm Pb, 0.15 % S. The paper focuses mainly on lab tests made with the aim to develop an effective formulation of self reducing - melting pellets. With such a formulation, agglomerates develop a breaking load higher than 125 - 150 kg without any thermal treatment. Zinc and lead are volatilized in the cupola with yields higher than 95 % at 1200 OC, before any melting. Sulphur is transfemed into gas and slag. All these conditions allow to lower zinc, lead and sulphur grades below the cast iron specifications. Results of first bench scale tests performed at Fonderie Piret to validate the process will be presented.

Jan 1, 2002

By Francois Reizine

Infrared sensors will include scanning detectors and positioning sensors. The focus will be on 1, 2, and 4-color wavelength pyrometer systems which allow the accurate measurement of emissivity and, consequently, of the true temperature even in the presence of scale, slag, and fumes. Such sensors are being used in blast furnaces, BOF&apos;s, and galvanizing lines. Laser sensors will be presented using different principles of physics, mainly time-of-flight, pulsed infrared lasers for level measurement and dimensional measurement; triangulation lasers for width and thickness measurements; and laser Doppler velocimeters for velocity and length measurements, including mass flow, elongation, and tension control, cut-to-length applications. These sensors and systems are based on state-of-the-art technical developments to improve productivity and quality and reduce maintenance and downtime.

Jan 1, 2001

By David J. Kinneberg, Barbara E. Mangion, Arnold M. Savolainen

Analytical laboratories require a qualitative or semi-qualitative method of determining major and minor constituents in "unknown" samples to select optimal analytical techniques. This is exceedingly important in precious metal assay laboratories where the precision and accuracy requirements are exacting (routinely within 0.02%, absolute basis). This paper describes the use of an x-ray fluorescence spectrometer with a specially designed software package to select optimal analytical procedures and specify relevant analytical parameters. A wavelength dispersive XRF spectrometer is capable of quick and accurate analyses of properly prepared samples without extensive standardization. When coupled with a specially designed software package, this preliminary assay system is applicable to a wide variety of sample types including gold and silver bullion, karat gold and karat PGM alloys, high silver and high copper metallic samples as well as particulate samples of ores and sweeps. The system relieves the assayer of tedious calculations for silver inquartation and proofing, minimizes human error and standardizes selections over time. Most importantly, the system allows for independent verification of final assay results.

Jan 1, 1999

By E. James Quinn

Solvent extraction technology using EHEHPA (2-ethylhexyl phosphonic acid, 2-ethyhexyl mono ester) is the norm for industrial separations of rare earth elements. This process has some shortcomings, including a large number of stages compared to most SX processes and high acid requirement for stripping of the heavy rare earths. In this work, we examine a number of alternative mixed solvent extraction systems: (i) Mixtures of organophosphonic and phosphinic acids such as EHEHPA/Cyanex 272 or Cyanex 572; (ii) Ionic liquid mixtures of EHEHPA with quaternary ammonium chloride (Aliquat 336); and (iii) Mixtures of carboxylic acids for yttrium/lanthanide separations. We discuss and compare the efficacy of these systems with reference to the Nd/Sm separation, which is of industrial significance. Based on the extraction chemistry and the use of modelling tools to define the counter-current solvent extraction circuit, we present a techno-economic analysis of a separation plant and discuss the impact of various solvent systems on the capital expenditure (CAPEX) and operating costs (OPEX).

By Wei Liu

A new process for extracting cadmium from the electric precipitated dust produced by ISP process was studied. A leaching rate of 89.1% of cadmium was attained by leaching the dust with NH3?H2O-(NH4)2SO4 system under the best leaching conditions: ratio of liquid to solid(l:s)=2.5, c(NH3):c(NH4+)=3:5, total concentration of ammonium and ammonia=8 mol?L-1, leaching time= 1.5h, temperature=35. The most troublesome impurity of lead could be deposited from the leached out solution automatically after put it static more than 15h when the total concentration of zinc and cadmium was up to 45gL-1 , and the final concentration of lead was 0.0047 gL-1, which meant 99% of it was removed. Metallic cadmium which contained cadmium more than 99% was prepared by electrowinning under the conditions: current density=750Am-2, total concentration of Cd2+ and Zn2+>25gL-1. The current efficiency was about 87% and the energy consumption for every ton of cadmium was about 548KWht-1. Main impurities of the metallic cadmium were copper and zinc and all of they could be got rid of in the following pyrometallurgical refining step.

Jan 1, 2006

By J. Pesl, U. Kemey, F. Sauert

"The CONTOP® smelting cyclone is a water-cooled, upright, high-intensity smelting reactor. The technology for the reactor was initially developed and brought into industrial-scale operation in the area of non-ferrous metallurgy. The two largest smelting cyclones were built with a capacity of 32 tons per hour of copper concentrate mix.The newest industrial CONTOP® plant treats up to five tons per hour of zinc-bearing residues including EAF dust. The highly concentrated zinc-lead oxide produced is sold to the zinc industry. The slag fulfills the leaching criteria and is used in waterway construction. The heat transferred to the cyclone cooling system and the off-gas boiler produces steam from which power is generated in a turbine.V AI has erected a new CONTOP® demonstration plant at MEFOS, Lulea, Sweden. A zinc volatilization rate of 90% was achieved during hot commissioning with Swedish EAF dust.Treatment costs in the range of 85 to 100 EUR per ton were estimated in a feasibility study on the treatment of 73,000 and 57 ,000 tons EAF dust for a group of steelmaking mills in Southern Europe."

Jan 1, 2000

By Vinay Kumar, Manis Kumar Jha, J. Rajesh Kumar, Archana Kumari, Rekha Panda, Jin Young Lee

Rare earth metals (REMs) play a significant role in the manufacture of permanent magnets, fluorescent lamps, catalysts, medicines, super alloys etc. Recently, China, which controls 97% of world trade in REMs, imposed restriction on its export. Consequently, the global demand of REMs is escalating and is expected to exceed the supply by 40,000 tonnes annually. Present review paper reports the flow-sheets of commercial processes based on pyro-hydro and hybrid techniques as well as systematic research for process development to recover REMs from primary and secondary resources. This review paper also reports the recommendation and future prospective to fulfill its demand and supply gap keeping in view environmental prospective.

Jan 1, 2014

By P. C. Chaubal

The overall kinetics of oxidation of single partic1es of chalcopyrite have been studied for temperatures up to 1273 K. The experiments were conducted in a stationary bed reactor using a non-isothermal technique. Any mass and heat transfer effects on the kinetics of oxidation were eliminated by using a high-enough gas flowrate. Up to temperatures of 873 K, pore-bl1ocking kinetics were applicable, whereas above 873 K, power-law kinetics gave a satisfactory fit of the data. The activation energy was 215 kJ/mol below 754 Kand 23.7 kJ/mol above 1,060 K. Predominance area diagrams were constructed at various temperatures and used in conjunction with X-ray analyses of partially oxidized samples to determine the intermediate phases formed during the reaction. The analysi1s also provides a justification for the kinetic models used. The results indicate that the reaction rate is first order with respect to oxygen concentration and inversely proportional to the square of the particle size throughout the ranges of temperature studied.

Jan 1, 1985