The effect of composition change and allocation in raw material on the carbonaceous structural evolution during calcination process

Fuel ◽  
2022 ◽  
Vol 309 ◽  
pp. 122173
Author(s):  
Zhichen Zhang ◽  
Enqiang Yu ◽  
Yanjun Liu ◽  
Fushan Wen ◽  
Nan Shi ◽  
...  
Keyword(s):  
Structural Evolution ◽  
Raw Material ◽  
Composition Change ◽  
Calcination Process

The Study of the Melting of Waelz Oxide with an Increase in the Temperature of the Calcination Process

2021 ◽  
Vol 316 ◽  
pp. 705-710
Author(s):  
A.G. Ryazanov ◽  
A.V. Senin ◽  
V.D. Nasonov
Keyword(s):  
Partial Melting ◽  
Gas Phase ◽  
Lead Oxide ◽  
Elevated Temperatures ◽  
Lead Sulfate ◽  
Raw Material ◽  
Chemical Transformations ◽  
Calcination Process ◽  
Waelz Oxide ◽  
Negative Effect

Waelz-oxide is a raw material for the production of metallic zinc. Waelz-oxide contains impurities of zinc and lead chlorides and fluorides. Halides have a negative effect on the process of zinc electrolysis. Halides have a relatively low boiling point; therefore, they are removed into the gas phase by calcining Waelz-oxide at 800–850 °С. To intensify the process, calcination is sometimes carried out at elevated temperatures of 1100–1250 °С. However, an increase in temperature leads to partial melting and granulation of the calcined product. In the present work, the chemical and phase composition of the initial and calcined Waelz-oxide was studied. Thermodynamic modeling of phase and chemical transformations of Waelz-oxide components during heating has been performed. Experiments on calcination of Waelz-oxide in laboratory conditions at temperatures of 600–1250 °C were carried out. It was found that partial melting and granulation of Waelz-oxide is the result of the formation of fusible eutectics containing lead oxide. Lead oxide is formed as a result of decomposition of lead sulfate when heated above 1100 °C. A similar effect is not observed at a standard calcination temperature of 850 °C.

Structural Evolution of Natural Flake Graphite with Different Particle Sizes during the Intercalation and Exfoliation Processes

2011 ◽  
Vol 80-81 ◽  
pp. 221-224
Author(s):  
Xue Qing Yue ◽  
Yan Lu ◽  
Dong Hua Lu
Keyword(s):  
Particle Size ◽  
Graphite Particle ◽  
Structural Evolution ◽  
Intercalation Compounds ◽  
Raw Material ◽  
Particle Sizes ◽  
Flake Graphite ◽  
Material Particle ◽  
Graphite Intercalation ◽  
Reaction Degree

In order to investigate the structural evolution of natural flake graphite with different particle sizes during the intercalation and exfoliation process, we used three natural graphites, 35, 50 and 80 mesh, as the raw material and investigated the characteristics of the three chemically prepared graphite intercalation compounds (GICs) of H2SO4 and the three corresponding residue GICs (RGICs). Expanded graphites (EGs) were prepared by rapidly heating the RGICs to 1000 °C in a muffle. The Results show that with decreasing the raw graphite particle size, the oxidizing reaction degree of GIC increases, but the intercalating reaction degree decreases. For RGICs, the relative ratio of RGIC phase in a sample decreases with decreasing the raw material particle size. In addition, decreasing the raw graphite particle size decreases the expanded volume of EG.

scholarly journals Compressive Strength and Water Absorption of Pavement Derived from Palm Oil Eco Processed Pozzolan (EPP) Material as Partial Cement Replacement

2020 ◽  
Vol 20 (2) ◽  
pp. 205
Author(s):  
Nurul Farhanah Mohd Kusaimi ◽  
Fazlena Hamzah ◽  
Junaidah Jai ◽  
Nurul Asyikin Md Zaki ◽  
Norliza Ibrahim
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Palm Oil ◽  
Bleaching Earth ◽  
Raw Material ◽  
Oil Refining ◽  
Partial Replacement ◽  
Calcination Process ◽  
Partial Cement Replacement ◽  
Pozzolanic Properties

Eco Processed Pozzolan (EPP) is derived from Spent Bleaching Earth (SBE) by the calcination process via heat treatment in the palm oil refining industry. EPP can be used as a partial replacement of cement as it contains a high amount of silica and has pozzolanic properties. Besides its properties, the sustainable production of EPP in the palm oil industry, abundantly available, and cheaper raw material have opened an opportunity to explore it as a cement substitute in pavement industries. This research aimed to study the properties of pozzolanic EPP and discover its potential as a partial substitute of cement in the pavement block's development. The compressive strength and water absorption of the formulated pavement block using EPP were analyzed in this study. Two sets of paving blocks were developed, namely, Set A, EPP was added as a partial replacement of the cement in pavement formulation at 20% - 90%, while in Set B, integration of EPP and Fly Ash (FA) was used as a partial replacement of the cement. The results indicated that the maximum addition of EPP into pavement formulation was 20%. The increment of EPP as a cement substitute in a formulation of more than 20% has reduced the compressive strength and increased the water absorption of the pavement. Simultaneously, the addition of FA and EPP in the formulation of hybrid pavement in Set B shows that the addition of FA has improved the compressive strength of the pavement and less water absorption was detected. The pavement’s highest compressive strength by addition of FA was 36MPa at the EPP was added of 15 – 20%. The study indicated that EPP could be used as a partial substitute of the cement, but addition of FA might require to improve pavement compressive strength.

scholarly journals The Mechanism of the First Hydration-Dehydration Cycle of Pure α- and β-CaSO4•0.5H2O

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
E. Abu Zeitoun ◽  
C. Pritzel ◽  
Y. Sakalli ◽  
R. Trettin
Keyword(s):  
Crystal Surface ◽  
Setting Time ◽  
Morphological Structure ◽  
Raw Material ◽  
Hydration Reaction ◽  
Dehydration Process ◽  
X Ray Diffraction ◽  
Calorimetric Analysis ◽  
Calcination Process ◽  
Dehydration Mechanism

The objective of this research was to understand the dehydration mechanism of technical dihydrate and the variation of the physical properties of β-hemihydrate after the first hydration-dehydration process. In this study, the recycling mechanism of different hemihydrate types as raw material was investigated. The influence of the first hydration-dehydration process on the hydration rate, microstructure, and mechanical properties of recycled hemihydrate were characterized by differential calorimetric analysis (DCA), calcium ion-selective electrode (Ca2+-ISE), conductivity, particle size distribution (PSD), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results showed that the formed hemihydrate after the first hydration-dehydration process differs in its properties than the unrecycled hemihydrate in some characteristics such as the morphological structure, number of surface, and side defects due to the grinding process after the first hydration step. In addition to the grinding step, the calcination process was responsible for increasing the number of defects on the crystal surface, which leads to a change in setting time and the microstructure of the recycled hemihydrate. Therefore, after the 1st reaction cycle of β-HH, the compressive strength decreases due to a decrease in the hemihydrate crystal size, an increase in the surface area, and an increase in the amount of water required to perform the hydration reaction. The obtained hemihydrate after the first hydration-dehydration process was in β form due to the applied calcination process after the first cycle.

scholarly journals Synthesis and characterization of novel porous La2Zr2O7 ceramic with ultralow thermal conductivity and excellent photocatalytic property

2021 ◽  
Author(s):  
Baosehng Xu ◽  
Debao LIU ◽  
Liyan GENG ◽  
Feifei ZHOU ◽  
Lijie QU ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Single Phase ◽  
Dye Degradation ◽  
Sol Gel ◽  
Structural Evolution ◽  
Photocatalytic Property ◽  
Mesoporous Structure ◽  
Calcination Process ◽  
Surface Areas

Abstract A novel porous La2Zr2O7 ceramic prepared by combining a sol-gel template method and high-temperature calcination process. The structural evolution and crystallisation behaviour of the samples were systematically characterized using SEM, XRD, TEM and Raman spectroscopy. The results indicated that the as-prepared porous La2Zr2O7 ceramic had a typical nanoparticles assembling and mesoporous structure with single-phase pyrochlore crystal structure. Meanwhile, the as-prepared porous La2Zr2O7 ceramic presented an ultralow room temperature thermal conductivity of 0.07 W/(m·K), high specific surface areas of 325.17 m2/g and a relatively high compressive strength of 11.95 MPa. What’s more, the as-prepared porous La2Zr2O7 ceramic possessed ideal photocatalytic activity owing to the unique 3-D porous structure, high crystallinity and large surface area. These reported studies are proposing some new insight to improve porous rare-earth zirconates ceramic for thermal insulation and dye degradation applications.

Microstructure and reactivity of small metal particles: The role of Ce additives

1992 ◽  
Vol 50 (1) ◽  
pp. 318-319
Author(s):  
L.D. Schmidt ◽  
K. R. Krause ◽  
J. M. Schwartz ◽  
X. Chu
Keyword(s):  
Atmospheric Pressure ◽  
Noble Metals ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Chemical Shifts ◽  
Catalytic Converter ◽  
Structural Evolution ◽  
Single Particles ◽  
Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

Mental representation of economic crisis in Italian and Swiss samples 1The authors would like to thank Maurizio Mistri for his help in the construction of items. This research was supported by a grant from the Italian Murst (ex 40%).

2001 ◽  
Vol 60 (1) ◽  
pp. 11-14 ◽  
Author(s):  
Lucia Savadori ◽  
Eraldo Nicotra ◽  
Rino Rumiati ◽  
Roberto Tamborini
Keyword(s):  
Economic Crisis ◽  
Mental Representation ◽  
Mental Representations ◽  
Social Contexts ◽  
Raw Material ◽  
National Context ◽  
Cluster Procedure ◽  
Total N ◽  
Two Samples ◽  
Important Symptom

The content and structure of mental representation of economic crises were studied and the flexibility of the structure in different social contexts was tested. Italian and Swiss samples (Total N = 98) were compared with respect to their judgments as to how a series of concrete examples of events representing abstract indicators were relevant symptoms of economic crisis. Mental representations were derived using a cluster procedure. Results showed that the relevance of the indicators varied as a function of national context. The growth of unemployment was judged to be by far the most important symptom of an economic crisis but the Swiss sample judged bankruptcies as more symptomatic than Italians who considered inflation, raw material prices and external accounts to be more relevant. A different clustering structure was found for the two samples: the locations of unemployment and gross domestic production indicators were the main differences in representations.

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