SYNTHESIS AND KINETICS CRYSTALIZATION ZEOLITE-NA FROM TAILING TAILINGS.
Bauxite tailings is by product derived from bauxite ore beneficiation. The beneficiation process is done by separating waste particles such as clay, roots, grain, bauxite ore <2 mm are discarded or be referred to as a waste product or tailings. High concentration of alumina and silica in bauxi...
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| Format: | Theses |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/78498 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Bauxite tailings is by product derived from bauxite ore beneficiation.
The beneficiation process is done by separating waste particles such as clay, roots,
grain, bauxite ore <2 mm are discarded or be referred to as a waste product or
tailings. High concentration of alumina and silica in bauxite tailings considered as
one of the reasons why these tailings can be used as base material in the making
new products, namely synthetic zeolites. Zeolites synthetic is selected because
zeolites are imported, expensive and have uniform properties and >150 types of
synthetic zeolites can be made commercially and even in industrial zeolite can be
used widely as an adsorbent, ion exchange, membranes, catalysts, etc. Chemical
analysis of bauxite tailings showed the composition of alumina (Al2O3) is
approximately 49,41%, silica (SiO2) is about 12,58%, hematite (Fe2O3) is
approximately 10,06% and some other inorganic oxides are at small amounts.
The conversion process bauxite tailings into zeolite is carried out by caustic fusion
between bauxite tailings and NaOH at ratios of 1:1,0; 1:1,5; 1:2,0 and 1:2,5 (w/w)
with temperature of 5500C for 90 minutes. The result caustic fusion product is
called frit which then leached with water. Leaching aims to obtain an extract Si
and Al dissolved in the form of sodium silicate and sodium aluminate wherein the
content of Si, Al and Na dissolved in solution is measured by AAS (Atomic
Adsorption Spectroscopy). Solution has been known content of Si, Al and Na is
made gel and set compositions molar ratio of 1,2Na2O.0,5SiO2.0,5Al2O3.10H2O
by adding a solution of sodium silicate (Na2SiO3) as the source of Si suitable
precursor in the synthesis zeolites. Crsytallization product is done by using the
hydrothermal method at low temperatures with variable temperatures of 100, 110
and 1200C and crystallization 2, 4, 6, 8, 10 and 12 hours. Zeolite-Na produced is
characterized by using XRD, SEM-EDS and BET.
The result showed that caustic fusion can form compounds among NaAlO2 and
Na2SiO3 soluble in water with high percent extraction of alumina is 99,78% and
silica is 27,03% with mass ratio bauxite tailing and NaOH 1:1,5 (w/w) in
temperature is 5500C for 90 minutes. The best crystallization obtained by highest
% crystallinity zeolite-Na is 92,3% in temperature 1200C for 12 hours. The
transformation kinetics marked a new crystallites that grow along the crystal
deformed which can be seen through the approach of kinetic model of the Avrami
and Arrhenius equations showing that the rate controlled by diffusion surface
crystallization with the type order 0,7688, 0,8988 and 0,9441 temperature range of
crystal growth 100-1200C and time 2-12 hours with the activation energy of 55,6
KJ/mol.K. Types of zeolite product is zeolite Na-P1 cell unit GIS (Gismondinea)
with the chemical formula Na6Al6Si10O32.12H2O, fine white powders, crystal size
1-2,5?m and the type of mesoporous product with a cubic shape that can be used
as adsorbent media and ion exchange. |
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