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By Richard S. Kunter

Artech Recovery Systems, Inc has developed a low pressure and temperature? leach process called the "Cashman Process" to extract metals from arsenical flue dusts and residues and fix the arsenic in an environmentally stable form as ferric arsenate (scorodite). The process was pilot tested at Hazen Research in an integrated plant including continuous recycle from August 1989 to October 1989 during which several tons of flue dust were processed. Based on this pilot program, the process was deemed technically feasible and produced commercially salable products. Residues from this pilot program were subjected to a long-term stability test jointly designed by PTI environmental services and the USEPA. The process, its versatility, and the nature of the products is discussed in some detail.

Jan 1, 1992

By D. Mishra

Electric arc furnace dust (EAFD) generated during the recycling of steel- scrap is classified as a hazardous waste for landfilling. This is because it contains leachable heavy metals such as zinc, lead,... Recovery of these metals could result in both resources conservation and resolving waste disposal problems. A study of the thermal reduction of a sample of EAFD was carried out in an inert gas atmosphere using coke as a reducing agent. Preferential volatilization of zinc and lead was achieved during the reduction process at about 800 "C. More than 96 % of both zinc and lead were removed from the dust and were recovered in the condensates. The treatment residue was essentially composed of iron oxides and almost free from heavy metals.

Jan 1, 2002

By QIE Jun-mao, DONG Fang, DENG Hao-hua

The DIL402C thermal dilatometer and STA449C thermal analyzer were employed to test the linear expansion and contraction coefficient，CP and DSC curve of 304 stainless steel. The result showed that the linear expansion coefficient range was 20.9700×10-6～21.5712×10-6 and the linear contraction coefficient range was 21.2528×10-6～21.9471×10-6.The linear expansion and contraction coefficient were higher than other steel grade，so the 304 stainless steel belonged to the crack sensitive steel. Because of the crystal phase transformation occurred during the 1000~1400 ℃,the curve of CP fluctuated obviously and the defects of casting blank occurred easily. Chosen 1414℃ as the liquidus temperature of 304 stainless steel based on the analysis results of DSC. The curve of DSC was unsmooth during 1450～1100℃，the crystal phase transformation occurs and thermal stability of slab was inferior.When the initial solidified shell formed in this temperature range,the thickness of the shell would be nonuniform and the surface defects occurred more easily.

Jan 1, 2015

By F. Tailoka

Microporous membranes have been used to create a very fine dispersion of bubbles which greatly enhances the mass transfer of electroactive species to the electrode. Using this system, it has been shown that it is possible to electrowin copper as a coherent planar deposit, at high current densities, from copper chloride solutions.

Jan 1, 1990

By I. D. Reznik

On blowing nickel matte in a converter without quartz, first the oxidation of metallic iron and a part of FeS occurs without evolving sulfur dioxide, the formed FeO dissolves in a sulphide smelt and form a homogeneous oxysulphide smelt. On further increasing the FeO content, the oxysulphide separates into 2 layers. Based on the laboratory investigation of FeO-(FeS+Fe°) - (Ni3S2+Ni°) ternary phase diagram we have identified the separation region at 1250°C. The boundaries of the separation region have the form of an arc and the composition of the separated oxysulphide layers is defined by the canodes. In the nickel or copper-nickel matte - silicacalcium oxide slag system at 1250°C three layers, namely sulphide, oxysulphide, and slag may be formed. A high slag basicity due to the presence of CaO can serve to enhance the activity of FeO; a low nickel content in the matte corresponds to a high concentration of FeS therein; FeO from slag and FeS from the matte form a homogeneous FeO-FeS solution, i.e. an oxysulphide layer. The investigation on the "Camebaks" apparatus and by the nuclear gamma-ray resonance spectroscopy method of the phase composition in a slowly cooled oxysulphide layer has shown the presence of four phases: wustite, troilite, ferronickel grains, and calcium oxide-silica inclusions. Knowledge of regularities in the oxysulphides formation makes it possible to use them in pyrometallurgy of nickel and cobalt or preventing their formation.

Jan 1, 1997

By Ramana. G. Reddy, Haoxing Yang

The electrodeposition of zinc from zinc oxide using urea and choline chloride mixture in a molar ratio 2:1 is investigated in different experimental variables, namely, the concentration of added [BMIM]HSO4, temperature, and applied cell voltage. The additive, [BMIM]HSO4, was determined to have beneficial effect on the current efficiency, energy consumed in the process and surface morphology of the deposits. The highest current efficiency (92.6%) and lowest energy consumption (2.92kWh/kg) was obtained for solution with 20mg/mL [BMIM]HSO4. The morphology showed the formation of absorbed additive layer on the cathode at higher concentration of additives. Experiments were conducted at different temperatures between 343K and 388K and at various applied cell voltages between 2.7V to 3.6V to determine the best experimental conditions. By varying temperature, highest current efficiency (91.3%) and lowest energy consumption (2.69 kWh/kg) was obtained at 373K. The electrodeposition process is enhanced between the applied voltage 3.0-3.3V by achieving lower energy consumption (2.75~3.06kWh/kg) and higher current efficiency (88.4~89.7%). SEM images showed grain size is significantly increased in higher applied voltages. While at higher temperatures, it seemed to generate particle growth as clusters at the outer deposit layer.

Jan 1, 2014

By J. R. Sarazin

Density driven convection during solidification has been recognized for some time to result in macrosegregation particularly when lower density alloying elements are rejected into the interdendritic liquid. The resulting segregates are commonly referred to as channels, freckles or A-segregates. Buoyancy driven convection leading to channel formation has been examined in three model systems possessing somewhat different materials parameters. They are the Pb-Sn eutectic system, the transparent aqueous-salt NH C1-H 0 4 2 eutectic system and the transparent organic succinonitrile-ethanol monotectic system. Convection in these systems is controlled by a balance of buoyant and viscous forces, which are strong functions of composition and temperature. Composition, temperature and flow velocity were measured and elimination of channels through heavier ternary additions is discussed.

Jan 1, 1991

By J. P. Evans

The modem copper smelter today utilizes tonnage oxygen for smelting concentrates, generating a high strength S02 off-gas leaving the smelter vessel. This gas stream, which also contains any unreacted oxygen, plus C02, N2 and H20, also carries with it the volatilized portion of heavy metals in the feed, plus partly oxidized sulfide concentrates. The time/temperature history and subsequent treatment of this off-gas stream emerging from the smelting furnace exit up to the acid plant can influence the partitioning and segregation of heavy metals in the off-gas circuit. Depending on this history, the type and characteristics of the chemical and physical reactions which. occur in the gas handling system can be influenced. This fact can also be used as a tool to adjust the separation of copper from heavy metals. In this paper, the impact of different time/temperature histories of the gas, due to different furnace geometries .and design, on the subsequent formation and characteristics of the smelter dust is examined. Based on the available data, several case histories drawn from examples using both bath and flash smelting technologies are analyzed from this perspective.

Jan 1, 1992

By J. P. Evans

The modem 'copper smelter today utilizes tonnage oxygen for smelting concentrates. ,generating a high strength S02 off-gas leaving the smelter vessel. This gas stream. which also contains any unreacted oxygen, plus CO2; N2 and H20. also carries with it the volatilized portion of heavy metals in the feed, plus partly oxidized sulfide concentrates, The time/temperature history and subsequent treatment of this off-gas stream emerging from the smelting furnace exit up to the acid plant can influence the partitioning and segregation of heavy metals, in the off-gas circuit. Depending on this history. the type and characteristics of the chemical and physical reactions which occur in the gas handling system 'can be influenced. This fact can also be used as a tool to adjust the separation of copper from heavy metals. In this paper, the impact of different time/temperature histories of the gas, due to different furnace geometries and design. on the subsequent formation and characteristics of the smelter dust is examined. Based on the available data. several case histories drawn from examples using both bath and flash smelting technologies are analyzed from this perspective.

Jan 1, 1992

By K. Narayana Swamy

Experimental results of 3-phase mixing in a physical model of a CCRL for metals refining, at high levels of bottom gas injection (up to a superfIcial gas velocity (Us) of 12.5 cm/min), are presented. A thermal tracer technique was used to elucidate both longitudinal mixing and interphase heat transfer. The results indicate that even under conditions of significant bottom gas injection, it should be possible to maintain acceptably low longitudinal mixing (D. < 20 cm2/s and D/uL < 0.1) in the CCRL. Interphase mass-transfer coefficients of the order of 0.02 cm/s and higher, are predicted from the measured interphase heat transfer coefficients using the mass and heat transfer analogy. Adequate performance is likely to be possible for an industrial CCRL, based on extrapolation of these results to full-scale conditions.

Jan 1, 1996

By Tatsuo Itou

Both sales volume of Aluminum Can and its recycling rate are remarkably increasing here in Japan. In 1993, recycled can volume was 11.78 billion cans ( 116,258 metric tons ) and its recycling rate 57.8 percent. We, MITSUBISHI MATERIALS CORPORATION. the leading manufacturer of aluminum can in Japan and our affiliated companies are very deeply involved in recycling used beverage cans ( U.B.C ) and recycling them back to can stock. In this paper. I would like to present the following; 1. Recent trend of beverage can consumption in Japan. 2. Trend of aluminum can and its recycling rate in Japan. 3. Future of aluminum can business in Japan.

Jan 1, 1995

By Gervais Soucy, François Quesnel, Pierre Hovington, Wen Zhu, Karim Zaghib, Jocelyn Veilleux

The properties of lithium titanates anodes in Li-ion batteries are highly dependent on their secondary constituents. While their main phase is usually constituted of Li4Ti5O12, significant quantity of lithium titanates compounds of various stoichiometry are often present, due to either the processing, usage or aging of the material. These may go underreported, as many of these spectrums overlap or display low signal in X-ray diffraction (XRD). Samples of nanosized lithium titanates synthetized by inductive plasma were characterized by XRD and scanning electron microscopy (SEM), as they provide a regular yet typical crystallite size and shape including multiple phases. A Rietveld refinement was developed to extract the composition of these samples. Mass balance through further annealing and differential scanning calorimetry (DSC) enthalpy measurements from phase transformations were also used as identification and validation techniques.

Jan 1, 2015

By Boyd Davis, Vladimiros Papangelakis, Joshua LaMarre, Jan de Bakker

"HCl leaching using molten salt hydrates has the potential to improve the extraction of nickel from laterite ores. However, as in other HCl leaching applications, recovery of HCl is key to process economics. Spray pyrohydrolysis, which is used in current chloride-based flowsheets, is associated with a high energy cost. The authors have developed a proposed laterite leach circuit using an alternative HCl recovery route. The leach circuit envisions a leach by concentrated (33%) HCl in an MgCl2 molten salt hydrate (MSH) or brine medium, followed by Ni/Co recovery and iron precipitation. Magnesium and chloride are precipitated from solution as magnesium hydroxychloride; this hydroxychloride is thermally decomposed to produce HCl gas. The proposed flowsheet employs a chloride leach circuit with simpler equipment and lower energy cost than in the conventional practice of pyrohydrolysis. Laboratory work investigated key aspects of the flowsheet, including precipitation of magnesium hydroxychlorides and their composition; magnesium hydroxychloride thermal decomposition; and iron control.Introduction As sulphide nickel ores become harder to mine and more complex to process, laterite ores will increase in importance. Laterite ore deposits can be divided into two main mineralogies. Limonite ores consist mostly of hydrated iron oxide, FeOOH, with 1-3% nickel substituting for the iron. Saprolite ores consist of iron-magnesium silicates, (Fe, Mg)2Si04, again with some nickel substituting for the metal ions. Limonite ores can be treated using the HP AL (High Pressure Acid Leach) process, in which the ore is reacted with sulphuric acid at high temperature in an autoclave. HP AL, however, cannot in general be used to treat saprolite ores because the magnesium enters solution and consumes sulphuric acid, which results in excessive spending on lixiviant. It is therefore desirable to find a hydrometallurgical process specifically for saprolite ores that can provide better results than the treatment options currently available."

Jan 1, 2011

By Bing Gao, Zhe Wang, Xiangdong Xing, Xueqi Zhang, Shan Ren, Jianliang Zhang

"In sintering, the flame front speed (bed permeability) and sinter qualities are greatly depended on the feed size, especially coke breeze and limestone particle size. It is well known that coke breeze provides sinter bed with heat to meet the demand of partial fusion and diffusion bonding while limestone reacts with iron ore to generate bonding phase in the sintering process. Accordingly, it is necessary to find the optimum combination of different particle size of coke breeze and limestone to yield sinter associated with better qualities. In this study, sinter was produced in the sinter pot with varying coke breeze and limestone particle size together in sintering of a coarse hematite iron ore. The sintering productivity was measured and all of the result sinters were examined by microstructure analysis and reduction degradation test (RDI test). For the sintering of a coarse hematite iron ore, it was found that the optimum mean particle size combination of coke breeze and limestone was 1. 71mm and 1.55mm in the sinter mix. On such a circumstance, sintering productivity was higher and the properties of sinter were better.IntroductionNowadays, as the main iron bearing burden material of modem blast furnaces, sinter has a great influence on the blast furnace operation. Sintering is a greatly complex process involving various chemical reactions to form kinds of mineral phases [1, 2]. In the sintering process, coke breeze is used for fuel and it generates heat to raise the green bed temperature. Limestone serves as flux and it reacts with iron ore to produce various mineral phases. On one hand, during the sintering process, the particle size of coke breeze can have an effect on temperature, atmosphere, the flame front speed and all of them act on the microstructure and mineral constitutions of sinter [3, 4]."

Jan 1, 2013

By S. Ozbilen, B. Erdogan, M. Erdogan

To study by thermal analyses the response of precipitation hardenable alloys of Al-Cu-Mg and Al-Li-Cu-Mg system to natural and artificial ageing, a series of ternary and quaternary Al-alloys with nominal compositions of Al-l.13wt%Cu-0:65wt%Mg (alloy-I), Al-1.15wt%Cu-0.57wt%Mg-0.07wt%Li (alloy-2), Al-l.19wt%Cu-0.56wt%Mg-0.75wt%Li (alloy-3), Al-2.0lwt%Cu-0.89wt%Mg (alloy-4), Al-2.14wt%Cu"0.56wt%Mg-0.07wt%Li (alloy-5) were used in the present investigation. Samples in the form of rolled sheets are subjected to water quenching at 25EC after solution treatment at 530EC for 20 min. Alloys were aged naturally at room temperature (25EC) up to 2 months and artificially at 190EC up to 2 days. By using differential scanning calorimetry (DSC) in the temperature range of25-300EC, differential thermal analysis (DTA) in the temperature range of25-600EC together with Vicker's hardness measurements, the response to natural and artificial ageing of the alloys used in the present study were investigated. It was observed that in these alloys, GPB(Cu, Mg) zones [Guinier-Preston zones with Cu and Mg] do form during water quenching at 20EC following solutionizing heat treatment. Natural ageing of the same alloys causes formation of more GPB(Cu, Mg) zones, which results in hardening in the alloys. Artificial ageing at 190EC up to l day results in GPB zone dissolution causing preliminary decrease in hardness values while two days of artificial ageing in the alloys cause S' (Al2CuMg) precipitation confirmed by DSC/DTA analyses resulting in an increase in hardness values. Li addition up to 0.75wt% helps T1 (Al2CuLi) and T 2 (Al6CuLi3) phase formation together with S' precipitation as DSC/DTA analyses show after the same heat treatment.

Jan 1, 1998

By Yuzura Sato

Viscosity has been measured for various molten binary alloys of nickel with iron, cobalt and chromium in order to clarify the behavior of viscous flow of molten nickel alloys. The entire concentration range for iron and cobalt and 0-67at% of chromium content were studied. The measurement method was an oscillating cup viscometry using an alumina crucible that was precisely machined. The temperature was up to about I 880K for all the measurements. The results represented good Arrhenian relationship although some measurements included overcooled temperatures. The isothermal viscosities increased monotonously with an addition of iron and chromium into nickel. The addition of cobalt increased after stationariness. The isothermal viscosities showed concave curves. Activation energies increased monotonously by adding all the elements into nickel. These phenomena were considered to be related to the thermodynamic properties &apos;such as the heat of mixing and the structures of mixture melts.

Jan 1, 2003

By Kenneth N. Ham

Hydrometallurgy covers a wide spectrum of areas and its knowledge base is enlarged and enhanced by contributions from many other fields. Dissolution of metals and alloys in aqueous media will be used to illustrate how rich the field of metal extraction can be. Comprehensive understanding of the fundamentals of metal and alloy dissolution in aqueous systems requires creative application of thermodynamic principles, solutions chemistry, ligand complexation theory, electrochemistry, transport phenomena and heterogeneous kinetics. In addition, recent developments in instrumentation in the fields of interfacial phenomena and corrosion have tremendously advanced the field of metal extraction in aqueous system. The close relationship between metal extraction in aqueous systems and various physicochemical phenomena occurring in corrosion and interfacial systems will be discussed and illustrated with examples.

Jan 1, 2002

By William Petruk

Many gold operations lose gold during processing because some ore characteristics which affect recoveries have not been determined, and consequently the plant could not be designed to account for them. The ore characteristics can be determined with mineralogical techniques by analyzing the plant feed, final tailings and mill products. The plant feed and/or final tailings are commonly analyzed first as a separate project. Mill products are analyzed only if the process employs a minerals separation circuit to produce a concentrate (e.g. secondary flotation circuit to concentrate gold-bearing arsenopyrite), and if assays and materials balances indicate a recovery problem in the minerals separation circuit. Many ores have been evaluated at CANMET on a confidential cost-recovery basis by custom-designing a work plan which was dependent upon the problem and on the characteristics of the ore. The reasons for gold losses have been identified in most cases, and suggestions for modifying flowsheets have been proposed. The methods used in performing the analyses are described in this paper, and non-confidential results from in-house projects are provided as examples of the benefits of such analyses. The analytical methodology involves a combination of the following procedures: -producing heavy mineral concentrates and identifying the gold minerals in the concentrates; -determining quantities of invisible gold in gold-bearing sulphides, sulpharsenides, etc. by SIMS; -determining quantities and liberation characteristics of all gold minerals and gold-bearing minerals in the sample; -finding and identifying gold minerals in silicates; -extensive grinding and cyanidation to determine the ultimate amount of cyanidable gold; -determining impact of clay minerals and graphite; -performing a mineral balance for the gold in each sample; -performing a materials balance to determine the distribution of the gold minerals, gold-bearing minerals, and other minerals throughout the flowsheet, and; -interpreting the results.

Jan 1, 1995

By H. M. . van der Donk

In this work an overview is given about the techniques available for the removal of metallic impurities from molten aluminium. The overview is focused on the removal of iron. Also, some experimental results are given about the creation of iron-rich intermetallic compounds in an aluminium system, which are subsequently removed by gravity segregation and filtration techniques. This work is part of an ongoing research project of three major European aluminium companies who are co-operating on the subject of recycling of aluminium packaging materials recovered from household waste by means of Eddy-Current techniques. Using this technique the pick-up of some contaminating metals, particularly iron, is almost unavoidable.

Jan 1, 1995

By T. C. -M. Cheng

Iron removal and disposal in zinc plants has imposed a major environmental challenge to the industry. Among the existing options of precipitating iron as jarosite, goethite, and hematite, the Hematite Process seems to be the best candidate for the future development of a waste-free technology, because of its potential of producing saleable iron oxide residues for feed in iron-steel making industry. Unfortunately, under the current practice of the Hematite Process, it is not possible to produce iron residues clean enough to meet the specifications of the said industry. In this paper, the practice of industrial hematite precipitation and the relevant technical literature are reviewed with the objective to identify the critical processing parameters which are responsible for the contamination of hematite, particularly with sulfur and zinc. The analysis is conducted from a crystallization theory standpoint with emphasis given to the role of supersaturation with respect to the cleanliness of hematite precipitates.

Jan 1, 1997