Kinetics and mechanism of silicothermic reduction process of calcined dolomite in magnetherm reactor

Morsi, I.M.; Ali, H.H.

doi:10.1016/j.minpro.2013.11.016

Cited by 18 publications

(8 citation statements)

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“…Proses dekomposisi dolomit menjadi MgO dan CaO sudah banyak dilakukan baik secara isothermal maupun non-isothermal [7][8][9][10][11][12]. Variabel proses sangat berpengaruh terhadap pembentukan kurva dan puncak fasa MgO dan CaO.…”

Section: Pendahuluanunclassified

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Pengaruh Suhu Kalsinasi Pada Proses Dekomposisi Dolomit

Royani¹,

Sulistiyono²,

Sufiandi³

2018

jsmi

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Proses dekomposisi dolomit menjadi MgO dan CaO merupakan proses penting mengingat kedua oksida tersebut banyak digunakan dalam berbagai aplikasi. Untuk melihat pengaruh suhu proses kalsinasi terhadap dekomposisi dolomit menjadi MgO dan CaO, maka dilakukan kalsinasi. Proses kalsinasi menggunakan tungku Muffle furnace dengan suhu sebesar 500 o C, 600 o C, 700 o C, 800 dan 900 o C. Sebanyak kurang lebih 100 gram/sampel dolomit dimasukkan dalam tungku dan dipanaskan dengan laju pemanasan 10 o C/menit pada berbagai suhu yang kemudian ditahan masing-masing selama 1 jam, 2 jam, 3 jam, 4 dan 5 jam. Produk kalsinasi kemudian ditimbang dan dikarakterisasi dengan X-Ray Diffraction (XRD) dan Scanning Electron Microscope (SEM). Hasil percobaan menunjukkan kalsinasi dolomit semakin meningkat seiring dengan kenaikkan suhu kalsinasi. Proses kalsinasi dolomit optimum tercapai pada suhu 900 o C selama 4 jam dengan pengurang berat mencapai 46,74 %. Berdasarkan perhitungan stoikiometri pengurangan berat 46,74 % menunjukkan bahwa 97,78 % dolomit terdekomposisi menjadi MgO dan CaO. Pembentukan fasa MgO dan CaO dari dolomit melalui dua tahapan yaitu tahapan pembentukan fasa MgO-CaCO 3 pada suhu 700 o C dan tahapan pembentukan CaO pada suhu 800 o C-900 o C. Kesimpulan yang didapatkan dari proses kalsinasi dolomit ini adalah peningkatan suhu kalsinasi dapat meningkatkan proses dekomposisi dolomit menjadi fasa MgO dan CaO.

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Section: Pendahuluanunclassified

“…Variabel proses sangat berpengaruh terhadap pembentukan kurva dan puncak fasa MgO dan CaO. Peningkatan laju pemanasan dekomposisi menyebabkan peningkatan ketinggian puncak dari MgO dan CaO [7]. Mekanisme dekomposisi parsial MgO dari dolomit bermula dari lepasnya gas CO 2 dan terbentuknya ion O 2pada permukaan dolomit.…”

Section: Pendahuluanunclassified

Pengaruh Suhu Kalsinasi Pada Proses Dekomposisi Dolomit

Royani¹,

Sulistiyono²,

Sufiandi³

2018

jsmi

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“…i= denote a standard ordering of the eigenvalues of A. Then A, A * is self-du is a standard ordering of the eigenvalues of A * (see [7,Proposition 8.7]).…”

Section: Introductionmentioning

confidence: 99%

“…There are some influence factors involved in this problem such as reduction temperature, reduction reaction rate, and the diffusion rate of magnesium vapor during the reduction process. The silicon in ferrosilicon first reacts with magnesium oxide to form SiO 2 that will further combines with CaO in calcined dolomite to form calcium silicate [6,7]. The high initial reaction temperature of silicon-reduced magnesium oxide leads to high heating temperature.…”

Section: Introductionmentioning

confidence: 99%

Phase transformation involved in the reduction process of magnesium oxide in calcined dolomite by ferrosilicon with additive of aluminum

Wang

2020

Green Processing and Synthesis

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AbstractMetal magnesium is mainly produced from the calcined dolomite by the silicothermic production. However, in this process, the reduction temperature is higher while the reaction speed is slow, which results in higher energy consumption and serious environmental problems. In this paper, adding aluminum into the ferrosilicon reducing agent is expected to lower the reaction temperature so as to solve the problems above. The phase transition involved in the whole reduction process including with and without aluminum addition were investigated in details by theoretical calculation and experimental research. The influence of aluminum on the magnesium oxide reduction path was analysis to clarify the internal mechanism. The results show that aluminum added into the ferrosilicon would first react with magnesium oxide to form magnesium vapor and alumina under vacuum pressure of 10 Pa when the temperature rises to 720°C. Then, calcium aluminate would be formed by the reaction of aluminum oxide and calcium oxide. Once the temperature reaches 1150°C, silicon begins to reduce the magnesium oxide to create the silicon oxide that will finally react with calcium oxide to form calcium silicate. When the temperature rises above 1150°C, both the aluminum and silicon will participate in the reduction of magnesium oxide. In the process of heating up, the mixture of aluminum, ferrosilicon and calcined dolomite forms Mg2Al4Si5O18 and Ca3Al2(OH)12 phase with the components in calcined dolomite. Mg2Al4Si5O18 and Ca3Al2(OH)12 phase finally form Ca12Al14O33 phase. The interaction between aluminum and ferrosilicon in the mixture is less; the mixture of aluminum and ferrosilicon first forms Al3FeSi2 phase, and finally has the trend of forming Al4.5FeSi phase. There is a great difference between the phase transformation of aluminum in the mixture of aluminum, ferrosilicon and calcined dolomite and that of aluminum in the mixture of aluminum and ferrosilicon.

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“…These studies rely on reducing calcination to achieve continuous production of Mg. Other researchers used an inert gas to replace the vacuum state. For example, Morsi studied the kinetics of the Mg process by using a silicothermic reduction process at 1 L/min argon (Ar) flow and found that the pellet reduction rate was up to 92% in an Ar atmosphere [19,20]. Further kinetics analyses of Mg production in Ar have been performed by Wulandari [21] and Chen [22].…”

Section: Introductionmentioning

confidence: 99%

Nucleation and Condensation of Magnesium Vapor in Argon Carrier

Han

Guo

et al. 2020

Metals

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The nucleation and condensation of Magnesium (Mg) vapor carried by argon gas (Ar) were examined. The condensation of Mg vapor at a heat source temperature of 1273–1473 K and Ar flow rate of 0.1–0.4 m3/h was analyzed. The result indicated that the condensation temperature is affected by the heat source temperature and Ar flow rate, and the condensation temperature of Mg vapor was 1013.3 K at a heat source temperature of 1473 K and Ar flow rate of 0.2 m3/h. The effects of Mg vapor partial pressure and temperature of the condensation zone on the nucleation and condensation of Mg vapor carried by Ar were calculated and analyzed in terms of atomic collisions and critical nucleation radius. Increased vapor oversaturation and decreased condensation temperature were favorable for liquid nucleation growth. The Mg condensation products in Ar flow rate of 0.2 m3/h at a heat source temperature of 1473 K were analyzed by XRD, SEM, and EDS, which indicated that the condensed product was of high purity and not easily oxidized in Ar flow. In this paper, the quality of Mg vapor condensation was controlled, which provided the theoretical and experimental basis for a continuous Mg production process.

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Kinetics and mechanism of silicothermic reduction process of calcined dolomite in magnetherm reactor

Cited by 18 publications

References 3 publications

Pengaruh Suhu Kalsinasi Pada Proses Dekomposisi Dolomit

Pengaruh Suhu Kalsinasi Pada Proses Dekomposisi Dolomit

Phase transformation involved in the reduction process of magnesium oxide in calcined dolomite by ferrosilicon with additive of aluminum

Nucleation and Condensation of Magnesium Vapor in Argon Carrier

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