scholarly journals Change in the phase composition of low-quality bauxites as a result of chemical activation

2021 ◽  
Author(s):  
R.A. Abdulvaliyev ◽  
◽  
A. Akcil ◽  
◽  
◽  
...  
Keyword(s):  
Phase Composition ◽  
Sodium Bicarbonate ◽  
Calcium Silicate ◽  
Chemical Activation ◽  
Fine Fraction ◽  
Silicate Phase ◽  
Activation Temperature ◽  
Mineral Structure ◽  
Composition Changes

As a result of separation of a fine fraction of gibbsite-kaolinite low-quality bauxite from the Krasnogorsky deposit, it is possible to increase its silicon module. When bauxite is chemically activated in a solution of sodium bicarbonate, the fine fraction is effectively separated from the large one and the phase composition changes – the calcium silicate phase disappears and the calcite phase is formed. With an increase in the activation temperature, the content of kaolinite and siderite decreases, the content of quartz and hematite increases. Studies have shown that at chemical activation temperatures of 120 oC, lasting more than 120 minutes and 200 oC, lasting more than 40 minutes, a dawsonite phase is formed in bauxite, which compacts the mineral structure. When determining the mode of chemical activation, it is necessary to take into account the negative possibility of the formation of dawsonite.

scholarly journals Modification of the phase composition of low-grade gibbsite-kaolinite bauxites

2021 ◽  
Vol 317 (2) ◽  
pp. 94-102
Author(s):  
R.A. Abdulvaliyev ◽  
◽  
S.B. Dyussenova ◽  
A.I. Manapova ◽  
A. Akcil ◽  
...  
Keyword(s):  
Phase Composition ◽  
Chemical Activation ◽  
Fine Fraction ◽  
Sodium Bicarbonate Solution ◽  
Microscopic Analysis ◽  
Coarse Fraction ◽  
Low Grade ◽  
Optimal Regime ◽  
Electron Microscopic ◽  
Activation Temperature

The known methods of processing low-quality bauxite have a number of disadvantages that make it difficult or impossible to use them in the conditions of production of JSC "Aluminum of Kazakhstan", therefore, it is necessary to effectively develop a technology for preliminary enrichment. Enrichment of low-quality bauxites is possible by separating the clayey - high-siliceous and coarse-crystalline fractions. Electron-microscopic analysis of the original bauxite showed that the coarse-crystalline fraction is tightly pressed by the fine one. The total silicon modulus of the sample is 2.49. The silicon modulus of the fine fraction is 2.19, and that of the coarse fraction is 3.89. When enriching bauxite, as a result of the separation of fines, it is possible to increase the silicon modulus. After the chemical activation of bauxite in a sodium bicarbonate solution, the finely dispersed fraction is effectively separated from the coarse one and the phase composition changes - the calcium silicate phase disappears and the calcite phase is formed. With an increase in the activation temperature, the content of kaolinite and siderite decreases, and the content of quartz and hematite increases. Studies have shown that at temperatures of chemical activation of 120 ° C, duration of more than 120 minutes and 200 ° C, duration of more than 40 minutes, a dawsonite phase is formed in bauxite, which densifies the mineral structure. When determining the optimal regime for carrying out chemical activation, it is necessary to take into account the negative possibility of dawsonite formation.

scholarly journals Research and development of a comprehensive technology for processing kaolinite clays in Kazakhstan

2021 ◽  
Author(s):  
S. Dyussenova ◽  
◽  
Ahmed A. M. El-Amir ◽  
◽  
◽  
...  
Keyword(s):  
Phase Composition ◽  
Sodium Bicarbonate ◽  
Raw Materials ◽  
Chemical Activation ◽  
Sodium Bicarbonate Solution ◽  
High Quality ◽  
Standard Methods ◽  
Mineral Raw Materials ◽  
Sodium Aluminosilicate ◽  
The Republic

In the Republic of Kazakhstan, the most promising are kaolinite clays of the Alekseevsky deposit. For effective processing of clays, it is necessary to develop special methods of processing, since satisfactory results were not achieved when using standard methods of gravity processing. The article provides the results of studies of the effect of preliminary chemical activation on the yield of the kaolinite fraction during gravitational processing. Previously, the method of preliminary chemical activation of raw materials in a solution of sodium bicarbonate has proven itself well in the processing of various mineral raw materials. It is determined that as a result of preliminary chemical activation, changes in the phase composition occurred. The dependence of the yield of the kaolinite fraction on the temperature of chemical activation, duration, and the ratio of W:T and the concentration of the sodium bicarbonate solution. Based on the results obtained, a technology for the complex processing of kaolinite clays has been developed, which provides for the preliminary chemical activation of the feedstock at the beginning of the process, which will effectively isolate high-quality kaolinite and quartz products, which will significantly reduce the flow of materials entering for sintering. As a result of activation, the phase composition of the kaolinite fraction has changed: the percentage of the kaolinite fraction has decreased; new phases of muscovite and sodium aluminosilicate appeared; the amount of quartz increased.

Analisis Variasi Temperatur Aktivasi Terhadap Daya Serap Arang Aktif Tandan Aren (Arenga Pinnata Merr) Dengan Agen Aktivasi Potassium Silicate(K2SiO3)

2020 ◽  
Vol 5 (3) ◽  
pp. 221
Author(s):  
Muhammad Azam ◽  
Muhammad Anas ◽  
Erniwati Erniwati
Keyword(s):  
Methylene Blue ◽  
Activated Carbon ◽  
Adsorption Capacity ◽  
Temperature Variation ◽  
Chemical Activation ◽  
Weight Ratio ◽  
Potassium Silicate ◽  
Physical Activation ◽  
Activation Temperature ◽  
Pyrolysis Reactor

This study aims to determine the effect of variation of activation temperature of activated carbon from sugar palm bunches of chemically activatied with the activation agent of potassium silicate (K2SiO3) on the adsorption capacity of iodine and methylene blue. Activated carbon from bunches of sugar palmacquired in four steps: preparationsteps, carbonizationstepsusing the pyrolysis reactor with temperature of 300 oC - 400 oC for 8 hours and chemical activation using of potassium silicate (K2SiO3) activator in weight ratio of 2: 1 and physical activation using the electric furnace for 30 minutes with temperature variation of600 oC, 650 oC, 700 oC, 750 oC and 800 oC. The iodine and methyleneblue adsorption testedby Titrimetric method and Spectrophotometry methodrespectively. The results of the adsorption of iodine and methylene blue activated carbon from sugar palm bunches increased from 240.55 mg/g and 63.14 mg/g at a temperature of 600 oC to achieve the highest adsorption capacity of 325.80 mg/g and 73.59 mg/g at temperature of 700 oC and decreased by 257.54 mg/g and 52.03 mg/g at a temperature of 800 oCrespectively.However, it does not meet to Indonesia standard (Standard Nasional Indonesia/SNI), which is 750 mg/g and 120 mg/g respectively.

scholarly journals Computer Analysis of the Effect of Activation Temperature on the Microporous Structure Development of Activated Carbon Derived from Common Polypody

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2951
Author(s):  
Mirosław Kwiatkowski ◽  
Jarosław Serafin ◽  
Andy M. Booth ◽  
Beata Michalkiewicz
Keyword(s):  
Activated Carbon ◽  
Porous Structure ◽  
Computer Analysis ◽  
Density Functional ◽  
Activated Carbons ◽  
Chemical Activation ◽  
Geometrical Parameters ◽  
Activation Process ◽  
Microporous Structure ◽  
Activation Temperature

This paper presents the results of a computer analysis of the effect of activation process temperature on the development of the microporous structure of activated carbon derived from the leaves of common polypody (Polypodium vulgare) via chemical activation with phosphoric acid (H3PO4) at activation temperatures of 700, 800, and 900 °C. An unconventional approach to porous structure analysis, using the new numerical clustering-based adsorption analysis (LBET) method together with the implemented unique gas state equation, was used in this study. The LBET method is based on unique mathematical models that take into account, in addition to surface heterogeneity, the possibility of molecule clusters branching and the geometric and energy limitations of adsorbate cluster formation. It enabled us to determine a set of parameters comprehensively and reliably describing the porous structure of carbon material on the basis of the determined adsorption isotherm. Porous structure analyses using the LBET method were based on nitrogen (N2), carbon dioxide (CO2), and methane (CH4) adsorption isotherms determined for individual activated carbon. The analyses carried out showed the highest CO2 adsorption capacity for activated carbon obtained was at an activation temperature of 900 °C, a value only slightly higher than that obtained for activated carbon prepared at 700 °C, but the values of geometrical parameters determined for these activated carbons showed significant differences. The results of the analyses obtained with the LBET method were also compared with the results of iodine number analysis and the results obtained with the Brunauer–Emmett–Teller (BET), Dubinin–Radushkevich (DR), and quenched solid density functional theory (QSDFT) methods, demonstrating their complementarity.

Highly Porous Carbon Derived from Sunflower Seed Shell for Electrochemical Capacitor

2011 ◽  
Vol 287-290 ◽  
pp. 1420-1423 ◽  
Author(s):  
Wei Xing ◽  
Xiao Li ◽  
Xiu Li Gao ◽  
Shu Ping Zhuo
Keyword(s):  
Pore Structure ◽  
Electrode Material ◽  
Sunflower Seed ◽  
High Performance ◽  
Chemical Activation ◽  
Electrochemical Capacitor ◽  
Drain Current ◽  
Porous Carbons ◽  
Activation Temperature ◽  
Highly Porous

Highly porous carbons were prepared from sunflower seed shell (SSS) by chemical activation and used as electrode material for electrochemical double layer capacitor (EDLC). The surface area and pore structure of the porous carbons are characterized intensively using N2 adsorption technique. The results show that the pore-structure of the carbons is closely related to activation temperature. Electrochemical measurements show that the carbons have excellent capacitive behavior and high capacitance retention ratio at high drain current, which is due to that there are both abundant macroscopic pores and micropore surface in the texture of the carbons. More importantly, the capacitive performances of these carbons are much better than ordered mesoporous carbons, thus highlighting the success of preparing high performance electrode material for EDLC from SSS.

Treatment of Dyeing and Printing Wastewater by Copper Oxide Loaded on Coconut Shell Activated Carbon

2011 ◽  
Vol 366 ◽  
pp. 412-415
Author(s):  
Yu De Liu ◽  
Bo Quan Jiang ◽  
Zheng Qiang Xiao
Keyword(s):  
Activated Carbon ◽  
Copper Oxide ◽  
Orthogonal Experiment ◽  
Chemical Activation ◽  
Copper Nitrate ◽  
Color Removal ◽  
Removal Rates ◽  
Activation Temperature ◽  
Coconut Shells ◽  
Coconut Shell Activated Carbon

The activated carbon loaded copper oxide catalyst was prepared from Hainan abandoned coconut shells using chemical activation method and applied in treatment of acid bright red GR simulation dyeing wastewater. The effects of phosphoric acid concentration, ratio of liquid to solid, activation time and activation temperature on the COD and color removal rates were investigated by orthogonal experiment. The results showed that the optimal values of the parameters above were 65% (in mass), 3:1, 2.5h and 500°C under the designed copper oxide loading conditions of calcining temperature 300°C,calcining time 3.0 h and use level of copper nitrate 15 mL. Using the prepared sample for the treatment of the wastewater, the COD and color removal rates reached 94.384% and 99.840%, respectively.

scholarly journals Microporosity Development of Herringbone Carbon Nanofibers by RbOH Chemical Activation

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Vicente Jiménez ◽  
Paula Sánchez ◽  
Fernando Dorado ◽  
José Luís Valverde ◽  
Amaya Romero
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Carbon Nanofibers ◽  
Flow Rate ◽  
Chemical Activation ◽  
Micropore Volume ◽  
Structure Development ◽  
Activation Temperature ◽  
Activating Agent ◽  
Activation Conditions

The influence of different activation conditions, including activating agent/CNFs ratio, activation temperature, and He flow rate, on the pore structure development of herringbone carbon nanofibers (CNFs) was studied. The best results of activated CNFs with larger specific surface area can be achieved using the following optimized factors: RbOH/CNFs ratio = 4/1, activation temperature = ,and a He flow rate = 850 ml/min. The optimization of these three factors leads to high CNFs micropore volume, being the surface area increased by a factor of 3 compared to the raw CNFs. It is important to note that only the creation of micropores (ultramicropores principally) took place, and mesopores were not generated if compared with raw CNFs.

Effect of hydration and air exposure on sorption properties and phase composition of calcium silicate hydrate

2014 ◽  
Vol 84 (13) ◽  
pp. 2596-2602
Author(s):  
P. S. Gordienko ◽  
S. B. Yarusova ◽  
A. P. Suponina ◽  
A. A. Yudakov ◽  
I. G. Zhevtun
Keyword(s):  
Phase Composition ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Sorption Properties ◽  
Air Exposure

Application of response surface methodology to optimize the fabrication of ZnCl2-activated carbon from sugarcane bagasse for the removal of Cu2+

2017 ◽  
Vol 75 (9) ◽  
pp. 2047-2055 ◽  
Author(s):  
Thuan Van Tran ◽  
Quynh Thi Phuong Bui ◽  
Trinh Duy Nguyen ◽  
Van Thi Thanh Ho ◽  
Long Giang Bach
Keyword(s):  
Response Surface Methodology ◽  
Activated Carbon ◽  
Response Surface ◽  
Sugarcane Bagasse ◽  
Interactive Effect ◽  
Chemical Activation ◽  
High Surface ◽  
High Surface Area ◽  
Aqueous Environment ◽  
Activation Temperature

The present study focused on the application of response surface methodology to optimize the fabrication of activated carbon (AC) from sugarcane bagasse for adsorption of Cu2+ ion. The AC was synthesized via chemical activation with ZnCl2 as the activating agent. The central composite design based experiments were performed to assess the individual and interactive effect of influential parameters, including activation temperature, ZnCl2 impregnation ratio and activation time on the AC yield and removal of Cu2+ ion from the aqueous environment. The statistically significant, well-fitting quadratic regression models were successfully developed as confirmed by high F- and low P-values (<0.0001), high correlation coefficients and lack-of-fit tests. Accordingly, the optimum AC yield and removal efficiency of Cu2+ were predicted, respectively, as 48.8% and 92.7% which were approximate to the actual values. By applying the predicted optimal parameters, the AC shows a surprisingly high surface area of around 1,500 m2/g accompanied by large pore volume and narrow micropore size at low fabrication temperature.

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