Search Documents

By I. H. Gundiler

Sandia National Laboratories (SNL) is tasked to support The Department of Energy in the dismantlement and disposal of SNL designed weapon components. These components are sealed in a potting compound, and contain heavy metals, explosive, radioactive, and toxic materials. SNL developed a process to identify and remove the hazardous sub-components utilizing real-time radiography and abrasive water-jet cutting. The components were then crushed, granulated, screened, and separated into an aluminum and a precious-and-base-metals fraction using air-tables. Plastics were further cleaned for disposal as non-hazardous waste. New Mexico Bureau of Mines & Mineral Resources assisted SNL in investigation of size- reduction and separation technologies.

Jan 1, 1995

By Reimers. Jan H.

Practically all the world's lead is produced by sintering and blast furnace smelting, or the Imperial Smelting Process which is a variant of the blast furnace process. Increased coke and labour costs and strict lead emission limits have, however, made blast furnace smelting undesirable in most countries. A change-over to other lead smelting processes providing better working conditions and lower emissions is, therefore,. expected to occur once economic conditions improve and the necessary capital expenditures can be justified. The need for new lead smelting processes has long been evident and a number of new processes have been proposed 'and advanced to various stages of development. One of the new processes is already proven on commercial scale, while several others are still being tested on pilot plant scale.

Jan 1, 1983

By G. Lissens

In this work the electrochemical combustion of dissolved organic species in a single compartment cell containing a titanium mesh cathode and a boron doped diamond anode has been studied, The organic molecules involved were complexing agents such as EDTA (ethylenediaminetetraacetic acid) or NTA (nitrilotriacetic acid) used in metal plating shops and bright nickel plating bath additives, From batch experiments, it is shown that complete decomplexing of EDTA and NIA is feasible. Complete TOC (Total Organic Carbon) removal from solutions containing 0.01 M EDTA, 0.02 M NTA and bright nickel plating bath additives could also be achieved. Recycling experiments show that decomplexing of EDTA and NTA solutions can be obtained at an average electrical energy input of ~20kWh.kg-1 of complexing agent. Decomplexing rates of respectively 3.l3 mmol.Ah-1 for EDTA and NTA have been obtained, The Instantaneous Current Efficiency (ICE) was 71% for EDTA and 95% by NTA, Simultaneous recovery of Cu from a 0.01 M Cu-EDTA solution has also been evaluated. A solution (1.8 dm3) containing 0.01 M EDTA and 528 ppm of Cu was treated in a single compartment cell at a current density of 2 A.dm-2. 73% of the TOC could be removed and a final copper concentration of 8 ppm was obtained.

Jan 1, 2003

By Brian R. Green

Resin-in-pulp (RIP) technology has been developed for recovery of gold. It is now time to look forward to the potential for application of the technology to other situations. Some cases have been identified and have merited preliminary testwork. Four examples, which illustrate the potential of RIP, are dealt with in this paper. These include removal of metal-cyanides from pulps, recovery of manganese that is difficult to wash from filter cakes, recovery of nickel from low grade pulps, and recovery of zinc from process residues. The discussion includes descriptions of the problems, factors that affect the choice of resin, and factors that will affect the economics of the process.

Jan 1, 1998

By Tullio Corsini

Scrap battery recovery process, developed by Engitec Impianti S.p.A., is improved transforming batches operations in continuous. Benefits expected: constant and better quality of the products; easier and more reliable control of the operating parameters, reduction of manpower requirements. Paste will content less sulfate, particularly in soluble form. Sodium sulphate is obtained with higher and constant purity.

Jan 1, 1993

By C. J. Newman

The Kidd Creek Copper Smelter has been expanded from its original design of 59,000 tonnes of copper per year to over 120,000 tonnes per year. Modifications to the process gas handling system and acid plant have been made to accommodate this higher production rate and to generally optimize the operation. The gas handling system associated with the continuous smelting process is discussed in terms of boiler accretions and modifications to minimize their impact on operations; design changes to effect reductions in high pressure drop duct configurations; material changes to overcome corrosion and plant additions to improve gas cleaning capability. The acid plant is reviewed with references to changes? made to accommodate the increased SO2 gas strength resulting from the higher smelting rates.

Jan 1, 1992

By Janusz Majta

The aim of this work is to investigate the control of microstructure evolution through variation of particular deformation parameters in the two-phase (intercritical) region. Niobium-microalloyed and low-carbon steels were investigated. A detailed examination of the factors affecting the ferrite microstructures of tested steels indicated that there were distinct advantages of finishing at temperatures in the austenite-ferrite region. The various results of deformation in the two-phase region are presented. Consequently, the influence of the most important process parameters on the microstructure evolution and mechanical response of the material is determined. The prime objective of the realized research work is the determination of relationship between the history of deformation and final product quality i.e. texture and mechanical properties. To reach the objective, the constitutive equations are proposed for modeling the effects of the hot-deformation process occurring in the austenite and austenite-ferrite region of low carbon and microalloyed steels on the mechanical properties of the resulting product. These models link advanced, finite element approaches simulating metal flow and heat transfer during hot-plastic deformation with constitutive equations describing microstructural processes and mechanical properties.

Jan 1, 2003

By Han Yihua, Zhang Caijun, Zhu Liguang, Zhang Qingjun, Wang Shuoming, Wang Yan

An industrial test on 210 t converter-LF-CC production line on high heat input welding shipbuilding structure steel DH36 has been taken in a factory in north China, the effect of adding microalloy elements V and Mg on casting billet microstructure has been researched. It was found that when the composition of V was between 0.03 and 0.05% and the composition of Mg was between 0.002 and 0.005%, a large number of acicular ferrite precipitate in austenitic crystal in as-cast structure and cross into a net structure. The inclusions size which induced intra-granular ferrite are mainly less than 4 lm, especially those between 2 and 3 lm account for 50.80%, in these inclusions the composite inclusions mixed with Mg accounted for more than 60%.

Mar 1, 2017

By Benjamin P. Hay

Complexation of a metal ion to a ligand often results in structural changes that introduce steric strain within the ligand. A design criterior:1 for ligands that will complex metal ions more strongly is to choose Iigar:1d architecture, that minimizes this strain. This paper describes how molecular mechanics models can be used to define the degree of ligand binding site organization in terms of' ,strain energies associated with conformational reorganization and distortion of the binding conformer. This approach yields a method to predict how modifications to ligand structure will affect metal binding affinity.

Jan 1, 1999

By Di Yang

The influence of high density (104 -105 A/cm2) electric current pulses (70 us duration) and continuous DC (~103 A/cm2) on the flow stress and ductility in tension of a high carbon steel wire were determined at 204°, 427° and 649°C. Electropulsing (100 pulses per second) with an effective current density of 100-200 A/cm2 gave a 10% enhancement in the uniform elongation of the wire at 204°C, but had no effect at 427°C and 649°C. In contrast, continuous DC either had no significant effect on the ductility or gave a decrease. The electropulsing per se decreased the flow stress only slightly at 204° and 427°C, but gave a significant decrease at 649°C. Continuous DC increased the flow stress at all three temperatures. The present results along with those by others suggest that the enhanced ductility by electropulsing and the reduction in flow stress may be further increased by raising the effective current density through increases in either the pulsing frequency, maximum current density of each pulse or pulse duration. This could conceivably increase the reduction per pass during wire drawing or the number of passes between anneals.

Jan 1, 2001

By F. Ajersch, P: Tsantrizos, K: Shanker

"TiN films have been deposited on various substrates by a novel reactive plasma technology. In this process, a nitrogen source (NH3 or N2) and TiCl4 are reacted in the jet of a plasma torch, and are deposited onto a substrate forming TiN films at a high growth rate ( > 2µm/min). It was found that the process parameters strongly affect the microstructure, thickness, density, and growth rate of the TiN films. These parameters include source of nitrogen (NH3 or N2, N/Ti ratio, temperature of substrate, and spray distance. In general, it was found that thick and dense coatings were deposited when the N:Ti ratio was kept low, and the substrate temperature was high. Also, for the series of conditions investigated, NH3 was found to give much better results than N2•. The limitations and advantages of this technique are also discussed in this paper.IntroductionTiN is an extremely hard material and is used in many wear applications, particularly as a protective coating on cutting tools to extend their Iife(1.2). Owing to its excellent chemical stability, TiN is also frequently used as a diffusion barrier in the electronics industry for sub-micron Al/TiN/Si ohmic contact systems (3) or as a coating on high-temperature resistant alloys in gas turbine applications (4), based on its good resistance to oxidation. Other applications include decorative coatings in the jewelry industry, and specialized applications such as solar energy absorbers and transparent heat mirrors(5).TiN films can be deposited/formed using various techniques. The main techniques of deposition are CVD (Chemical Vapour Deposition) and PVD (Physical Vapour Deposition). Each of these techniques can have many variations in equipment characteristics, reactants as well as a range of process parameters (pressure and temperature). In the CVD process, TiN is generally deposited onto a heated substrate where a chemical reaction takes place. The reaction can be one of reduction(6) (e.g.: TiCI4 + 0.5N2 + 2H2 --> TiN + 4HCI), of thermal decomposition(7) (e.g. decomposition of titanium dialkylamide), or of displacement (e.g. TiCI4 + NH3 --> TiN + 3HCI + 0.5CI2)' The displacement and reduction reactions are the most common."

Jan 1, 1994

By John A. Mavrogenes

The Texaco gasification system developed at the Monte Bello pilot plant efficiently bums petroleum-coke thereby producing syn-gas and electricity. This system produces more electricity than conventional burners, yet the only by-products are pharmaceutical grade sulfur and V -rich slag. Vanadium is known to exist in multiple valence states in compounds which possess a wide range of melting points and physical properties. Consequently, it becomes important to carefully regulate oxygen fugacity throughout the system in order to control vanadium valence state. Vanadium phase equilibria is presently poorly understood, in large part because of the multiple oxidation states of vanadium (-I, 0, +2, +3, +4, and +5) and the difficulty of unequivocally identifying the valence state(s) in many compounds. The operation of these gasifiers at approximately 1400°C is well above the melting point of V20S but considerably below the melting temperature of V02 and V 203. If J02 can be regulated to keep the burner within the V 205 field, slag material would more likely remain molten and more easily flow out of the bottom of the burner. In pure V oxides. the oxidation state is readily determined by microprobe analysis. where V20S (V+5) is 56% V, V02 (V+4) is 61.4% V, and V203 (V+3) is 68% V. However, V valence in multi-element phases (especially phases containing other elements of variable valence) cannot be resolved by microprobe analysis alone. Petroleum-coke gasification slags collected from within the gasifier under different oxidation conditions were studied by electron microprobe analysis (EMPA). X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Raman spectrometry in conjunction with microprobe analysis was found to resolve the valence of vanadium in the phases of these slags. Raman spectra collected from homogeneous single phase V-oxide standards in vacuum at low temperatures (-150°C) yielded peaks characteristic to each valence state. Gasifier slag samples are, however, much more complicated. Oxidized samples contain: fine grained (Ca. Mg, Fe. V) oxide matrix of variable composition, (Fe. V, Ni) spinel. (Fe, AI, V, Ni, Mg) spinel, V205laths, AI-Si glass blebs and Ni sulfides. Reduced samples contain: crystalline Ca-siIicate matrix, subhedral to euhedral (V, Fe, Mg, AI) spinel, subhedral V02, Fe and Fe-Ni sulfides, Fe-Ni alloys, and complex Ca-oxide matrix. The different spinel assemblages, the characteristic V-oxides and the distinctly different character of the matrices makes the oxidized and reduced slags readily discernible.

Jan 1, 1995

By S. Mattlgod

Self-assembled monolayers on mesoporous supports (SAMMS) have been developed for the removal of heavy metals and some transition metals. The thiol functional groups were assembled on the internal and external surfaces of mesoporous silica with a uniform pore size of about 55 A. The mesoporous supports provide high surface area (>900 m2/g) needed for high metal loading in chemical separation. Self-assembled monolayers of organic molecules bond to the ceramic substrate with prescribed densities, and with terminal functional groups for excellent molecular selectivity. The unique characteristics include: (1) High metal absorption capacity, up to 3.2 mmol/g of SAMMS. (2) Fast Hg-binding kinetics (reducing mercury concentration from 0.5 ppm to 0.5 ppb in less than 5 minutes). (3) High selectivity in the presence of a range of cations, anions, and organic species. (4) Applicability in both aqueous and non-aqueous solvents. (5) Flexibility in surface chemistry. The materials can be designed to adsorb heavy metals, transitional metals, and radionuclides. (6) Chemical stability, and potential for regeneration or waste storage. This paper discusses the results on mercury adsorption.

Jan 1, 1999

By F. R. A. Jorgenson

The ignition of chalcopyrite and pyrite was studied using laminar flow furnace and thermal analysis techniques which were supported by XRD and optical microscopic examination of the products. In air, chalcopyrite and pyrite ignited at temperatures of 400-500'C and 500-600?C respectively. The phase assemblages predicted from thermodynamic analyses were compared with those found by experiment, and the onset of ignition was correlated against changes in the phase compositions. Pyrite and chalcopyrite ignited when pyrrhotite and intermediate solid solution formed thus opening up the structure and allowing ready access of oxygen.

Jan 1, 1989

By Jing Zhan, Gui Li, Wei-feng Li, Li-Hua Jiang, Chuan-fu Zhang, Jian-yang Hwang

Thermodynamics analysis for processing the charge with lead concentrate and lead sulfate-containing materials in bottom blowing smelting furnace was conducted. The results show that the technology of large-scale processing PbSO4- containing materials with PbS concentrate in bottom blowing furnace under the condition of using high-iron slag type, batch heat supplement, high temperature and rich oxygen is thermodynamically feasible. The exploration test and industrial experiment confirm the results. When S content in mixed ore is 16~17% with coke foam content of about 5%, the lead paste amount can be increased up to 40%.

Jan 1, 2015

By D. J. Senor

Closed chamber incineration (CCI) is a novel technique by which irradiated nuclear graphite may be destroyed without the risk of radioactive cation release into the environment. The process utilizes an enclosed combustion chamber coupled with molten carbonate fuel cells (MCFCs). The transport of cations is intrinsically suppressed by the MCFCs, such that only the combustion gases are conducted through for release to the environment. An example CCI design was developed which had as its goal the destruction of graphite fuel elements from the Fort St. Vrain reactor (FSVR). By employing CCI, the volume of high level waste from the FSVR will be reduced by approximately 87 percent. Additionally, the incineration process will convert the Sic coating on the FSVR fuel particles to SiO2, thus creating a form potentially suitable for direct incorporation in a vitrification process stream. The design is compact, efficient, and makes use of currently available technology.

Jan 1, 1994

By Markus A. Reuter, Robert Matusewicz

"Consumer products are a complex man-made mixture of sometimes in excess of 50 elements. In order to recover these complex mixtures of elements either as metals, compounds or energy requires versatile technology in physical separation but also smelting and energy recovery. This paper explores this by referring to the innovative application of Top Submerged Lance (TSL) technology and associated theoretical and environmental aspects to process (recycle) post consumer materials and industrial intermediate products and residues. A diversity of applications has been tested in Ausmelt’s pilot plant in Dandenong and many have gone to commercial scale globally. This paper reviews the varied applications ranging from e-waste recycling, lead and NiCd battery recycling, metals recovery from slags, zinc leach residue processing, electric arc furnace (EAF) dust, Municipal Waste Incinerator bottom ash processing, carbon containing residues such as retort ashes and spent pot liner from the aluminium production process as well as use of the technology for materials such as automotive shredder residue (ASR) and plastics. Introduction The modern resource cycle is a link between primary production of metals linked to the recycling of post-consumer goods. The sometimes complex combinations of materials and metals in consumer products such as televisions depicted by Figure 1, does require a range of technology to recover materials, metals and energy for reuse and/or recycling in an economically feasible as well as environmentally friendly manner."

Jan 1, 2008

By Milton Manrique

The thermal decomposition of zircon concentrates in a non-transferred arc thermal plasma flow reactor was investigated. The plasma torch was operated using argon-helium and argon-nitrogen mixtures as plasma gases. The effect of power, feed rate and zircon particle size was studied. Products were characterized by XRD, SEM, TEM and chemical analytical techniques. The average size of the product was in the submicron range. Free energy minimization plots were used to predict the behavior of the system under different operating conditions. A kinetic model to describe the different stages of the thermal decomposition process is proposed. The results of this investigation showed a significant segregation process where the zirconia-rich product is collected in the reactor while the silica-rich product is collected in the filter. TEM analysis indicated that silica vapor is condensed on the surface of the zirconia particles.

Jan 1, 1996

By F. Elgersma

A high purity electrolysis solution is essential for hydrometallurgical zinc winning processes. For this reason ferric iron containing compounds such as jarosite are precipitated as iron and impurity collector during the calcine leaching. Jarosite thus forms a chemical waste and creates environmental problems. This research contributes to the development of a wet jarosite treatment process, where less contaminated jarosite is produced which can act as an iron source. The present work studies jarosite precipitation kinetics and the uptake of zinc cations in batch and continuous experiments. The distribution coefficient for zinc in continuous experiments is constant for a wide ratio of zinc over ferric ions in the solution. Addition of NH, + ions in batch experiments accelerates the conversion rate equivalent to the driving force increment. Addition of 50,2-ions above the stoichiometric ratio increases the conversion rate less then could be expected from the increase in the estimated driving force. Zinc ions tend to retard the conversion rate. An increasing reaction temperature increases the conversion rate. Below 75 ?C the conversion rate approximates zero.

Jan 1, 1990

By René Winand

A new process was studied at large laboratory scale at Université Libre de Bruxelles, under contract with Metallurgie Hoboken-Overpelt. A two cathodes (1m long ; 0.2 m high) channel cell was used at 2000 A/m2, with an electrolyte flow rate up to 1.8 m/sec. The main results may be summarized as follows : cathodes are electro¬refined grade in analysis ; metallographic structure and surface roughness are kept under control up to 1.3 cm (one side deposits) ; silver in cathode is controlled by CI and Br ions in solution ; organics must be used at very low concentrations (in the range of 0.1 mg/1, with a consumption of about 0.01 mg/lh).

Jan 1, 1987