scholarly journals Hydration Features of Composite Binding Material with High-Dose Copper Tailings

2021 ◽  
Vol 45 (1) ◽  
pp. 17-24
Author(s):  
Yang Wang ◽  
Hanxi Wang ◽  
Linwei Yang ◽  
Li Qian
Keyword(s):  
Hydration Process ◽  
High Dose ◽  
Mass Concrete ◽  
Copper Tailings ◽  
Granulated Blast Furnace Slag ◽  
Binding Material ◽  
Different Temperatures ◽  
Hydration Model ◽  
Center Particle ◽  
Parameter Values

Based on Krstulovic-Dabic model, this paper modifies the center particle hydration model according to the features of copper tailings, and then simulates the hydration process of cement-based composite binding system mixed with copper tailings. The hydration exothermic features were analyzed under different dosages, and different temperatures. Then, the simulated parameter values of the hydration process were compared with those measured in experiments. The results show that: the mixing of copper tailings powder can reduce the hydration heat release and slow down hydration rate of the composite binding material, and improve the thermal performance of the concrete; the prepared copper tailings powder is active enough to replace fly ash and ground-granulated blast furnace slag (GGBS) as cement admixtures; When the dosage surpasses 40%, the copper tailings can be applied to mass concrete projects.

scholarly journals A Logistic Approach for Kinetics of Isothermal Pyrolysis of Cellulose

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 551
Author(s):  
Jorge López-Beceiro ◽  
Ana María Díaz-Díaz ◽  
Ana Álvarez-García ◽  
Javier Tarrío-Saavedra ◽  
Salvador Naya ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Time Derivative ◽  
Inert Atmosphere ◽  
Second Step ◽  
Rate Parameter ◽  
Thermogravimetric Data ◽  
Different Temperatures ◽  
Parameter Values ◽  
Kinetics Of ◽  
Logistic Functions

A kinetic model is proposed to fit isothermal thermogravimetric data obtained from cellulose in an inert atmosphere at different temperatures. The method used here to evaluate the model involves two steps: (1) fitting of single time-derivative thermogravimetric curves (DTG) obtained at different temperatures versus time, and (2) fitting of the rate parameter values obtained at different temperatures versus temperature. The first step makes use of derivative of logistic functions. For the second step, the dependence of the rate factor on temperature is evaluated. That separation of the curve fitting from the analysis of the rate factor resulted to be very flexible since it proved to work for previous crystallization studies and now for thermal degradation of cellulose.

scholarly journals The Effect Of Hydrazine Addition On The Formation Of Oxygen Molecule By Fast Neutron Radiolysis

KnE Energy ◽  
2016 ◽  
Vol 1 (1) ◽  
Author(s):  
G.R. Sunaryo
Keyword(s):  
Room Temperature ◽  
Pure Water ◽  
Water System ◽  
Calculation Model ◽  
High Dose ◽  
Primary Coolant ◽  
Batch System ◽  
Different Temperatures ◽  
Oxygenated Water ◽  
Deaerated Condition

<p>Hypothetically speaking, hydrazine could suppress the oxygen formation as a major of corrosion initiator. In this work, we developed a calculation model to understand the effect of hydrazine addition toward the oxygen under PWR condition. Our great interest is to study whether this strategy would also be effectively applied in PWRs<a href="file:///C:/Users/Mohamad%20Mostafa/Desktop/Knowledge%20E/In%20Press%20Conferences/ICoNETS-2015/Source-Manuscripts/20_L05-Geni_p136-141.docx#_msocom_1">[P1]</a> . In the present work, the effect of hydrazine on suppressing the molecule oxygen under neutron irradiation is described.  The simulation was done by using FACSIMILE.  The variation dose applied assuming a batch system and at high dose ~10<sup>4</sup> Gy s<sup>-1</sup>.  Three different temperatures were applied, which are room temperature, 250 and 300 <sup>o</sup>C at two system oxygenated water, which are aeration and deaeration. At room temperature, for deaerated condition, added hydrazine under a range of 10<sup>-6</sup> – 10<sup>-4</sup> M into primary coolant were not effective to suppress  O<sub>2 </sub>form since the effect was similar as in the pure water system since for 10<sup>-3</sup> M hydrazine addition, a large produce of O<sub>2 </sub>were obtained. In reverse, for deaerated condition, hydrazine concentrate about 10<sup>-3</sup> M can suppress O<sub>2</sub> form significantly, while hydrazine add in the range between 10<sup>-6</sup> – 10<sup>-4</sup> M is again confirmed to be the same as in pure water system. For high temperature, at 250 and 300 <sup>o</sup>C, the results showed that in deaerated condition, hydrazine addition can suppress  O<sub>2  </sub>form<sub> </sub>proportionally to its concentration while in aerated condition, hydrazine add with concentration of 10<sup>-6</sup> and 10<sup>-5</sup> M were not effectively to suppress O<sub>2  </sub>form,<sub> </sub>a slightly decrease of O<sub>2</sub> occurred due to the addition of 10<sup>-4</sup> M hydrazine and 10<sup>-3</sup> M of hydrazine can suppress the formation of O<sub>2</sub> significantly. <a href="file:///C:/Users/Mohamad%20Mostafa/Desktop/Knowledge%20E/In%20Press%20Conferences/ICoNETS-2015/Source-Manuscripts/20_L05-Geni_p136-141.docx#_msocom_2">[P2]</a> </p><div><hr align="left" size="1" width="33%" /><div><div><p> <a href="file:///C:/Users/Mohamad%20Mostafa/Desktop/Knowledge%20E/In%20Press%20Conferences/ICoNETS-2015/Source-Manuscripts/20_L05-Geni_p136-141.docx#_msoanchor_1">[P1]</a>The added sentence</p><p> </p></div></div><div><div><p> <a href="file:///C:/Users/Mohamad%20Mostafa/Desktop/Knowledge%20E/In%20Press%20Conferences/ICoNETS-2015/Source-Manuscripts/20_L05-Geni_p136-141.docx#_msoanchor_2">[P2]</a>The revised sentence</p></div></div></div>

Background subtraction and moments of the microscopic density fluctuation

2002 ◽  
Vol 35 (2) ◽  
pp. 220-227 ◽  
Author(s):  
Roger Sobry ◽  
Salvino Ciccariello
Keyword(s):  
Background Subtraction ◽  
Density Fluctuation ◽  
Density Fluctuations ◽  
Algebraic Expression ◽  
Real Samples ◽  
Background Contribution ◽  
X Ray ◽  
Different Temperatures ◽  
Parameter Values ◽  
Best Fit

Some models of microscopic density fluctuations are numerically analysed in order to study the behaviour of the related background contribution. The results suggest that this contribution can be described by an algebraic expression depending on only the moments of the microscopic density fluctuation. In this way, the parameter values, determined by a best-fit procedure to account for background contributions in the case of real samples, acquire a definite physical meaning. The procedure is applied to the small-angle X-ray intensities of a polymer sample analysed at different temperatures and yields satisfactory results.

scholarly journals Sequential In-Situ Carbonation Process for the Preparation of Hand Sheets with Waste Lime Mud

Reactions ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 3-15
Author(s):  
Ramakrishna Chilakala ◽  
Thriveni Thenepalli ◽  
Seongho Lee ◽  
Hong Ha Thi Vu ◽  
Lai Quang Tuan ◽  
...  
Keyword(s):  
Paper Industry ◽  
Hydration Process ◽  
Smelting Process ◽  
Green Liquor ◽  
Carbonation Process ◽  
White Liquor ◽  
Lime Mud ◽  
Different Temperatures ◽  
Sample Purification ◽  
Process Elements

In the pulp and paper industry, the white liquor obtained from the causticizing green liquor in the smelting process mostly contains NaOH and Na2S. These chemicals are returned to the digester for reuse in the pulping process. The lime mud (LM) material is obtained from the reaction of the causticization process in paper industries. It is mainly composed of CaCO3; it appears with a green color with a high moisture content; and it has a small proportion of impurities such as non-process elements, for example Fe, Na, Mg, Al, Si, P, and S oxides and other toxic metals. This lime mud has poor whiteness with less efficiency due to its contaminated with impurities. The recycling or reutilizing process for lime mud and solid wastes are minimizing its toxic effect on the environment. The present study proposed to improve the whiteness of the waste lime mud by the calcination and hydration process at high temperatures and reutilizing it for hand sheets, making the process improve the paper brightness. In this study, we used a lime mud sample for calcination at 1000 °C and 1200 °C for 2 h and hydration at different times (3–24 h) with different temperatures (30–80 °C) and measured the powder whiteness and hand sheet brightness. The results indicated that after the calcination and hydration process, the lime mud sample whiteness was improved and that re-utilization with pulp for making hand sheets also can improve the paper brightness. It can be concluded that waste lime mud sample purification and the re-utilization process are more advantageous in paper industries.

A Constitutive Law of Salt Concrete Used for Closure of an LILW-Repository

2003 ◽  
Author(s):  
H. J. Engelhardt ◽  
M. Kreienmeyer ◽  
C. Lerch ◽  
N. Mu¨ller-Hoeppe ◽  
R. Ko¨ster ◽  
...  
Keyword(s):  
Setting Time ◽  
Heat Of Hydration ◽  
Constitutive Law ◽  
Numerical Code ◽  
Model Parameters ◽  
Mass Concrete ◽  
Degree Of Hydration ◽  
Equivalent Age ◽  
Setting Process ◽  
Hydration Model

The Repository of LILW Radioactive Waste Morsleben (ERAM) is located in the Federal State Saxony Anhalt, Germany. After an operational phase of about 20 years it is now under licensing for closure. As the repository was erected in a former salt mine, there exists a void volume of approx. 6 million m3. Consequently, a closure concept was developed serving three main functional requirements: stabilization, limitation of leaching processes and sealing. It relies on a comprehensive backfilling of the openings using two mixtures of salt concretes. The concretes will be used to backfill cavities as well as to construct seals. As the salt concretes are used in the sense of a mass concrete the heat of hydration induces thermal restraint stresses inside the concrete bodies and the neighboring rocks. To show the integrity of the geological and technical barriers thermo-mechanical computations were carried out. In the numerical code which is used for safety analyses a so-called hydration model was implemented describing the evolution of strength and Young’s modulus of the concretes in relation to the degree of hydration. The hydration model includes a transformation of the temperature-dependent setting process from real time into an equivalent age, which is equal to the setting time at a temperature of 293 K. Thereafter, a coupling of the equivalent age to the degree of hydration leads to a temperature-independent description of the setting process. As the hydration of concretes strongly correlates with the amount of the generated hydration heat, the model parameters were derived from laboratory tests including measurements of the adiabatic temperature rise.

Modeling of hydration reactions to predict the properties of slag blended concrete

2014 ◽  
Vol 41 (5) ◽  
pp. 421-431
Author(s):  
Xiao-Yong Wang ◽  
Ki-Bong Park
Keyword(s):  
Portland Cement ◽  
Cement Hydration ◽  
Blended Cement ◽  
Numerical Procedure ◽  
Reaction Model ◽  
Heat Evolution ◽  
Mineral Admixture ◽  
Temperature History ◽  
Granulated Blast Furnace Slag ◽  
Hydration Model

The granulated blast furnace slag is commonly blended with Portland cement or clinker to produce slag blended cement after being ground to the fineness comparable to Portland cement. Hydration of slag-blended cement is much more complex than that of ordinary Portland cement because of the mutual interactions between the cement hydration and the slag reaction. In this paper, by considering the production of calcium hydroxide in cement hydration and its consumption in the reaction of slag, a numerical procedure is proposed to simulate the hydration of concrete containing slag. The numerical procedure includes two sub components, a cement hydration model and a slag reaction model. The heat evolution rate of slag concrete is determined from the contributions of the cement hydration and the slag reaction. Furthermore, the temperature history in hardening blended concrete is evaluated by combining the proposed numerical procedure with a finite element method. The proposed model is verified through experimental data on concrete with different water–cement ratios and mineral admixture substitution ratios.

Experimental Study on Compound Binding Material of Alkali Activated Metakaolin and Ground Granulated Blast Furnace Slag

2011 ◽  
Vol 287-290 ◽  
pp. 1275-1279
Author(s):  
Yong Jia He ◽  
Lin Nu Lu ◽  
Shu Guang Hu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Hydration Product ◽  
Alkali Activation ◽  
Granulated Blast Furnace Slag ◽  
Binding Material ◽  
Measurement Results ◽  
Furnace Slag ◽  
Alkali Activated

Compound binding material was prepared by the alkali activation of metakaolin and ground granulated blast furnace slag. Hydration product components, microstructure and mechanical properties of the hardened paste were investigated by IR, XRD, SEM, MIP, and compressive strength measurement. Results indicated that hydration products included C-S-H and geopolymer, and both of them were amorphous although there were differences in their structure and morphology. When the dosage of slag was less than 50%, the compressive strength of hardened paste increased as the dosage increased, which was mainly because C-S-H produced by the reaction of GGBFS and alkali filled void in geopolymer phase, and part of unreacted slag particles acting as microaggregate to prevent from extension of microcrack in the hardened paste, so the porosity of hardened paste decreased and compressive strength increased.

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