scholarly journals A Mineralogical Investigation of Sintering in Cu-Rich Polymetallic Concentrates During Roasting in Inert Atmosphere

2020 ◽  
Vol 51 (4) ◽  
pp. 1446-1459 ◽  
Author(s):  
Pande Nishant Prasad ◽  
Andreas Lennartsson ◽  
Caisa Samuelsson
Keyword(s):  
Solid Solution ◽  
Inert Atmosphere ◽  
Oxidation Potential ◽  
Practical Relevance ◽  
Fundamental Study ◽  
Sulphide Minerals ◽  
System 2 ◽  
Sintering Mechanisms ◽  
Mineralogical Investigation ◽  
Impurity Elements

AbstractFour different Cu-rich polymetallic concentrates (additionally comprising Zn, Pb and impurity elements As, Sb) from various deposits in Sweden are examined, in particular for the sintering tendency during roasting in inert atmosphere. Experiments performed in a laboratory-scale roasting setup between 200 °C and 700 °C in intervals of 100 °C revealed that significant sintering initiates from 500 °C for all four concentrates. Two sintering mechanisms are determined from the examination of the sintered calcines: (1) solid-state assimilation of Cu-, Zn- and Fe-bearing main sulphide minerals to form a high-temperature solid solution, the iss phase belonging to the Cu-Fe-Zn-S system; (2) low-melting liquid phase formation due to partial melting of galena facilitated by the presence of impurity-bearing minerals, mainly the arsenopyrite and Sb sulphosalts such as tetrahedrite. Galena also forms a melt below 700 °C with the iss phase. Therefore, the presence of galena in polymetallic concentrates generally increases the susceptibility to early sintering. These experiments in inert atmosphere facilitate a fundamental study with practical relevance to the roasting in low oxidation potential environments, favourable for volatilization of impurity elements such as As and Sb.

scholarly journals A Mineralogical Investigation on Volatilization of Impurity Elements from Cu-Rich Polymetallic Concentrates During Roasting in Inert Atmosphere

2021 ◽  
Author(s):  
Pande Nishant Prasad ◽  
Iris McElroy ◽  
Andreas Lennartsson ◽  
Caisa Samuelsson
Keyword(s):  
Solid Solution ◽  
Liquid Phase ◽  
Inert Atmosphere ◽  
Laboratory Scale ◽  
Mineralogical Investigation ◽  
Impurity Elements ◽  
Concentrate Production ◽  
Melt Phase

AbstractFour different Cu-rich polymetallic concentrates are tested for volatilization of Sb and As during laboratory-scale roasting. The experiments are performed between 200 °C and 700 °C, at intervals of 100 °C and in an inert atmosphere. Sb volatilization is much less (maximum approximately 45 pct) than As volatilization (maximum approximately 95 pct) in these conditions at 700 °C. As volatilization is however limited from the concentrate having As mainly in a tetrahedrite solid solution ((Cu,Ag,Fe,Zn)12(Sb,As)4S13). Sb and As retained in the roasted calcine are found in the low-melting liquid phase, formed at approximately 500 °C. This melt phase gets enlarged and enriched in Sb with an increase in temperature. However, there is noticeable As volatilization from this melt phase with the temperature approaching 700 °C. Furthermore, there is an early and relatively high Sb volatilization from the concentrate having Sb substantially as gudmundite. Micron-scale elemental redistribution in gudmundite in the 350 °C roasted calcine confirms its transformation at this temperature. Other Sb minerals did not undergo any detectable transformation at this temperature, suggesting that the significant Sb volatilization starting between 300 °C and 400 °C was primarily from gudmundite. This benign attribute of gudmundite featured in this work in the context of roasting should also be relevant from the geometallurgical perspective during concentrate production, where concentrates bearing Sb are considered substandard for further Cu extraction irrespective of the Sb mineralogy.

TANTALOY 60 METAL

Alloy Digest ◽  
1988 ◽  
Vol 37 (4) ◽  
Keyword(s):  
Solid Solution ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Chemical Process ◽  
Heat Treating ◽  
Inert Atmosphere ◽  
Solid Solution Alloy ◽  
Temperature Performance ◽  
Temperature Exposure

Abstract TANTALOY 60 Metal is a vacuum-melted, solid-solution alloy of tantalum and tungsten. It retains useful strength up to 4500 F. Its corrosion resistance is similar to unalloyed tantalum and it is only slightly more difficult to fabricate. If high-temperature exposure is under conditions other than vacuum or inert atmosphere, coating protection may be required. The alloy is used in highly specialized and sophisticated aerospace system applications and in special chemical process. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Ta-9. Producer or source: Fansteel Metallurgical Corporation.

The role of actively diffusing impurities of sulfur and oxygen in ductility-dip cracking susceptibility of Ni-Cr-Fe welds

2018 ◽  
Vol 2 (89) ◽  
pp. 49-55 ◽  
Author(s):  
K.A. Yushchenko ◽  
A.V. Zviagintseva ◽  
L.M. Kapitanchuk ◽  
I.S. Gakh
Keyword(s):  
Solid Solution ◽  
Grain Boundary ◽  
Sample Surface ◽  
Formation Of Cracks ◽  
Boundary Model ◽  
Heating Up ◽  
Impurity Elements ◽  
Content Design

Purpose: To determine the temperature conditions of sulphur and phosphorus moving to sample surface for alloys with different initial sulphur content. Design/methodology/approach: Investigation of samples from In 690, Kh20N16AG6, In52MSS alloys in Auger spectrometer JAMP-9500F for determination of the probability of saturation of the free surface (as grain boundary model) with sulphur from the solid solution. Results obtained without removing the samples from the chamber, stage-by-stage heating up to 800°C with determination of element content every 100°C. Findings: It is shown that sulphur has the tendency of diffusing to the interface from the middle of the grain body and forming segregations in the form of a monolayer even at its slight (0.00015 wt.%) content in the alloy. Research limitations/implications: Presence of actively diffusing impurities (C, O, H, S, P), dissolved in the metal, in the case of a gradient of temperatures and stresses, leads to redistribution of these impurities between the solid solution and surface of the sample, or solid solution and grain boundaries (interface). According to the obtained data, change of elemental composition proceeds within 0.5-1 nm from the grain boundary or from the sample surface and leads to formation of monolayers. Practical implications: To prevent the formation of cracks it is necessary not only to reduce the content of impurity elements in the alloy, but to prevent moving them to the boundary of grains and creating mono layers. Originality/value: For the selected alloys, the formation of monolayers is the most intensive at temperatures of 700-800° that coincides with DTR in the temperature range of 0.6-0.8 Ts. Such monolayers can lead to ductility dip cracks formation.

Influence of Magnesium on Structure and Properties of Al-Si Alloy

2007 ◽  
Vol 23 ◽  
pp. 291-294 ◽  
Author(s):  
Mohammad M. Haque ◽  
Ahsan Ali Khan
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Solid Solution ◽  
High Resistance ◽  
Base Alloy ◽  
Deformation Behaviour ◽  
Low Density ◽  
Structure And Properties ◽  
Silicon Alloys ◽  
Impurity Elements

Aluminium-silicon alloys have low density, high electrical and thermal conductivity and high resistance to corrosion at ambient temperature. However, these alloys usually contain numerous alloying and impurity elements, which consist essentially of a fairly ductile matrix of alpha aluminium solid solution with a variety of non-ductile particles of silicon and various intermetallic compounds. The shape and distribution of these constituents largely control the deformation behaviour of the alloy. The addition of magnesium makes the alloys lighter and harder, but its hardening effect is fully responsive only after proper heat treatment. Therefore, in the present study, microstructures and properties of the alloys have been evaluated on the as-cast and heattreated conditions. Results show that the addition of magnesium to aluminium-silicon eutectic base alloy refines microstructure up to certain level and increases the strength and hardness at the expense of ductility.

Niocalite-cuspidine solid solution and manganoan monticellite from natrocarbonatite, Oldoinyo Lengai, Tanzania

2004 ◽  
Vol 68 (5) ◽  
pp. 787-799 ◽  
Author(s):  
R. H. Mitchell ◽  
F. Belton
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Oxygen Fugacity ◽  
Late Stage ◽  
Compositional Data ◽  
Silica Content ◽  
Solid Solution Series ◽  
Oldoinyo Lengai ◽  
Sulphide Minerals ◽  
Solution Series

AbstractLapilli and spatter of natrocarbonatite extruded from the T56B cone of Oldoinyo Lengai (Tanzania) in August 2003 are unusually rich in apatite, silicate, oxide and sulphide minerals. These minerals occur primarily within inclusions of quenched natrocarbonatite in gregoryite and fractures in nyerereite-gregoryite intergrowths. Silicates include members of the sodian cuspidine–niobian cuspidine–niocalite solid-solution series and manganoan monticellite. Oxides are represented by members of the magnesioferrite–jacobsite–magnetite solid-solution series. Sulphides occurring in decreasing order of abundance include: ferroan alabandite, manganoan ferroan sphalerite, galena and pyrrhotite. Petrographic and compositional data for these minerals are interpreted to indicate that all are high-temperature (<900–650°C), early-crystallizing phases from relatively-unevolved natrocarbonatite magma, with the sulphides forming prior to the silicates, and the latter before gregoryite. Sulphur fugacityand oxygen fugacity of natrocarbonatite magma are considered to decrease and increase, respectively, during the formation of the sulphide-oxide assemblage. Crystallization of cuspidine-niocalite, monticellite and Si-bearing apatite rapidly depletes natrocarbonatite magma of its initial low silica content, preventing crystallization of late-stage groundmass silicates.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

The oxidation of Inconel alloy MA754 at low oxidation potential

1983 ◽  
Vol 41 ◽  
pp. 218-219
Author(s):  
D. N. Braski ◽  
P. D. Goodell ◽  
J. V. Cathcart ◽  
R. H. Kane
Keyword(s):  
Surface Layer ◽  
Oxidation Potential ◽  
Metal Interface ◽  
Elevated Temperature Strength ◽  
Surface Conditions ◽  
Inconel Alloy ◽  
Inco Alloy ◽  
Resistance To Oxidation ◽  
Oxide Particles ◽  
Cold Worked

It has been known for some time that the addition of small oxide particles to an 80 Ni—20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance is being studied collaboratively by ORNL and INCO Alloy Products Company.Initial experiments were performed using INCONEL alloy MA754, which is nominally: 78 Ni, 20 Cr, 0.05 C, 0.3 Al, 0.5 Ti, 1.0 Fe, and 0.6 Y2O3 (wt %).Small disks (3 mm diam × 0.38 mm thick) were cut from MA754 plate stock and prepared with two different surface conditions. The first was prepared by mechanically polishing one side of a disk through 0.5 μm diamond on a syntron polisher while the second used an additional sulfuric acid-methanol electropolishing treatment to remove the cold-worked surface layer. Disks having both surface treatments were oxidized in a radiantly heated furnace for 30 s at 1000°C. Three different environments were investigated: hydrogen with nominal dew points of 0°C, —25°C, and —55°C. The oxide particles and films were examined in TEM by using extraction replicas (carbon) and by backpolishing to the oxide/metal interface. The particles were analyzed by EDS and SAD.

NiAl precipitation in Fe-12w/o Cr-5w/o Ni-4w/o Al

1983 ◽  
Vol 41 ◽  
pp. 202-203
Author(s):  
L.E. Murr ◽  
J.S. Dunning ◽  
S. Shankar
Keyword(s):  
Solid Solution ◽  
Stainless Steel ◽  
Stainless Steels ◽  
Alloy Composition ◽  
Chromium Content ◽  
Scale Up ◽  
Optical Metallography ◽  
Property Evaluation ◽  
310 Stainless Steel ◽  
Microstructural Studies

Aluminum additions to conventional 18Cr-8Ni austenitic stainless steel compositions impart excellent resistance to high sulfur environments. However, problems are typically encountered with aluminum additions above about 1% due to embrittlement caused by aluminum in solid solution and the precipitation of NiAl. Consequently, little use has been made of aluminum alloy additions to stainless steels for use in sulfur or H2S environments in the chemical industry, energy conversion or generation, and mineral processing, for example.A research program at the Albany Research Center has concentrated on the development of a wrought alloy composition with as low a chromium content as possible, with the idea of developing a low-chromium substitute for 310 stainless steel (25Cr-20Ni) which is often used in high-sulfur environments. On the basis of workability and microstructural studies involving optical metallography on 100g button ingots soaked at 700°C and air-cooled, a low-alloy composition Fe-12Cr-5Ni-4Al (in wt %) was selected for scale up and property evaluation.

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