TY  - CONF
AU  - Milovanović, Biljana
AU  - Oljača, Đurđa
AU  - Pavlović, Stefan
AU  - Ostojić, Gordana
AU  - Obrenović, Zoran
PY  - 2019
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/3796
AB  - Removal of some impurities from Bayer liquor, such as zinc compounds, allows obtaining alumina with low content of impurities incorporated in the crystalline structure. Impurities in alumina influence the quality of products obtained from alumina during electrolysis. In this research, the purification method presented in our previous paper was used for the purification of Bayer liquor, from which alumina was produced [1]. Crystallization of Bayer liquor was conducted at 52 °C during 24 h, whereas aluminium hydroxide with specific structural properties was used as the seed. The crystallization product (aluminium hydroxide) was calcined at 950 °C for 2 h with the heating rate of 5 °C min–1. The obtained alumina (Alumina I) is compared with alumina obtained without Bayer liquor purification (alumina from bauxite refinery „Alumina“ l.t.d., Zvornik, B&H – Alumina II). Zinc content is determined by atomic absorption spectroscopy. Structural and morphological properties are characterized by XRD, FT‐IR, N2‐physisorption, and particle size analyzer. Zinc content as ZnO in the initial and purified Bayer liquor was 0.0494 g dm–3 and 0.0057 g dm–3, respectively. Alumina from bauxite refinery contains 0.0260% ZnO, whereas the zinc content in alumina obtained after Bayer liquor purification was 0.016% ZnO. XRD analysis (Figure 1) showed that crystal structure is not destroyed and characteristic lines for both samples are at a 2Theta angle: 34.2, 37.2, 40.7, and 49.8. Bands characteristic for γ‐Al2O3 and α‐Al2O3 in pseudoboehmite structure can be observed at low wavenumbers in the obtained FT‐IR spectra [2]. Specific surface area and average pore diameter are shown in Table 1. These values are similar for both alumina samples.
PB  - Hrvatska: Hrvatsko društvo kemijskih inženjera i tehnologa
(HDKI)
C3  - Book of Abstracts - 26th Croatian Meeting of Chemists and Chemical Engineers with international participation and 4th Symposium Vladimir Prelog
T1  - Alumina production from purified Bayer liquor
T1  - Proizvodnja glinice iz pročišćene Bayerove otopine
SP  - 182
UR  - https://hdl.handle.net/21.15107/rcub_cer_3796
ER  - 

@conference{
author = "Milovanović, Biljana and Oljača, Đurđa and Pavlović, Stefan and Ostojić, Gordana and Obrenović, Zoran",
year = "2019",
abstract = "Removal of some impurities from Bayer liquor, such as zinc compounds, allows obtaining alumina with low content of impurities incorporated in the crystalline structure. Impurities in alumina influence the quality of products obtained from alumina during electrolysis. In this research, the purification method presented in our previous paper was used for the purification of Bayer liquor, from which alumina was produced [1]. Crystallization of Bayer liquor was conducted at 52 °C during 24 h, whereas aluminium hydroxide with specific structural properties was used as the seed. The crystallization product (aluminium hydroxide) was calcined at 950 °C for 2 h with the heating rate of 5 °C min–1. The obtained alumina (Alumina I) is compared with alumina obtained without Bayer liquor purification (alumina from bauxite refinery „Alumina“ l.t.d., Zvornik, B&H – Alumina II). Zinc content is determined by atomic absorption spectroscopy. Structural and morphological properties are characterized by XRD, FT‐IR, N2‐physisorption, and particle size analyzer. Zinc content as ZnO in the initial and purified Bayer liquor was 0.0494 g dm–3 and 0.0057 g dm–3, respectively. Alumina from bauxite refinery contains 0.0260% ZnO, whereas the zinc content in alumina obtained after Bayer liquor purification was 0.016% ZnO. XRD analysis (Figure 1) showed that crystal structure is not destroyed and characteristic lines for both samples are at a 2Theta angle: 34.2, 37.2, 40.7, and 49.8. Bands characteristic for γ‐Al2O3 and α‐Al2O3 in pseudoboehmite structure can be observed at low wavenumbers in the obtained FT‐IR spectra [2]. Specific surface area and average pore diameter are shown in Table 1. These values are similar for both alumina samples.",
publisher = "Hrvatska: Hrvatsko društvo kemijskih inženjera i tehnologa
(HDKI)",
journal = "Book of Abstracts - 26th Croatian Meeting of Chemists and Chemical Engineers with international participation and 4th Symposium Vladimir Prelog",
title = "Alumina production from purified Bayer liquor, Proizvodnja glinice iz pročišćene Bayerove otopine",
pages = "182",
url = "https://hdl.handle.net/21.15107/rcub_cer_3796"
}

Milovanović, B., Oljača, Đ., Pavlović, S., Ostojić, G.,& Obrenović, Z.. (2019). Alumina production from purified Bayer liquor. in Book of Abstracts - 26th Croatian Meeting of Chemists and Chemical Engineers with international participation and 4th Symposium Vladimir Prelog
Hrvatska: Hrvatsko društvo kemijskih inženjera i tehnologa
(HDKI)., 182.
https://hdl.handle.net/21.15107/rcub_cer_3796

Milovanović B, Oljača Đ, Pavlović S, Ostojić G, Obrenović Z. Alumina production from purified Bayer liquor. in Book of Abstracts - 26th Croatian Meeting of Chemists and Chemical Engineers with international participation and 4th Symposium Vladimir Prelog. 2019;:182.
https://hdl.handle.net/21.15107/rcub_cer_3796 .

Milovanović, Biljana, Oljača, Đurđa, Pavlović, Stefan, Ostojić, Gordana, Obrenović, Zoran, "Alumina production from purified Bayer liquor" in Book of Abstracts - 26th Croatian Meeting of Chemists and Chemical Engineers with international participation and 4th Symposium Vladimir Prelog (2019):182,
https://hdl.handle.net/21.15107/rcub_cer_3796 .

TY  - CONF
AU  - Oljača, Đurđa
AU  - Milovanović, Biljana
AU  - Pavlović, Stefan
AU  - Smiljanić, Radenko
AU  - Obrenović, Zoran
AU  - Filipović, Radislav
PY  - 2018
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/3771
AB  - The presence of Zn compounds in alumina reduces the current efficiency during electrolysis and quality of obtained metal. The known methods for Zn compounds removal that involves the use of different chemical agents (e.g. sulphide) are uneconomical and not environmentally friendly. In this research, aluminium-hydroxide with specific structural properties (AHSSP) was used as a crystallization agent during purification of Bayer liquor. The specific structural properties of the used aluminium-hydroxide are related with a small particle size (<8μm), small specific surface area (≈3 m2/g), and large pore diameter (≈1μm). Mechanism of Zn removal is based on crystallization phenomenon of aluminium-hydroxide from Bayer liquor where the AHSSP presents crystallization agent (seed). The crystallization process is conducted to a certain Na2O/Al2O3 ratio, which corresponds to a satisfactory aluminium concentration in Bayer liquor. The crystallization process was conducted in laboratory crystallization vessels (2 dm3) equipped with a heater and stirrer. The crystallization temperature was 50±1°C and the concentration of aluminium-hydroxide as crystallization agent (seed) was 15, 20 and 30g/l. The concentration of Al, Na, and Zn in Bayer liquor and solid crystallization product (aluminium hydroxide as seed and aluminium hydroxide from Bayer liquor) was analysed by using ICP-OES (Specto Genesis) and AAS (Shimadzu AA7000). The particle size of the obtained solid crystallization product was analysed by Cilas 1090, laser particle size analyser. The specific surface area was determined by using Gemini VII, whereas the pore structure was analysed by using Mercury intrusion porosimetry (Carlo Erba Porosimeter 2000). The obtained results show that the per cent of removed Zn compounds was above 80 for 2h, whereas Al concentration decreased slightly less than 20% for the same time. Structural analysis is shown, that particle size and pore diameter were increased, whereas the specific surface area was decreased. For this reason, the possibility of using the aluminium-hydroxide as a product of this process, without structural modification, is maximally two times. Keywords: Zn-compounds, crystallization, alumina, and structural properties.
PB  - Association of Technology Engineers of Republic of Srpska
C3  - Proceedings - XII Conference of Chemists, Technologists and Environmentalists of Republic of Srpska
T1  - Zinc removal from Bayer liquor by using aluminium hydroxide with specific structural properties as crystallization agent
SP  - 155
EP  - 158
UR  - https://hdl.handle.net/21.15107/rcub_cer_3771
ER  - 

@conference{
author = "Oljača, Đurđa and Milovanović, Biljana and Pavlović, Stefan and Smiljanić, Radenko and Obrenović, Zoran and Filipović, Radislav",
year = "2018",
abstract = "The presence of Zn compounds in alumina reduces the current efficiency during electrolysis and quality of obtained metal. The known methods for Zn compounds removal that involves the use of different chemical agents (e.g. sulphide) are uneconomical and not environmentally friendly. In this research, aluminium-hydroxide with specific structural properties (AHSSP) was used as a crystallization agent during purification of Bayer liquor. The specific structural properties of the used aluminium-hydroxide are related with a small particle size (<8μm), small specific surface area (≈3 m2/g), and large pore diameter (≈1μm). Mechanism of Zn removal is based on crystallization phenomenon of aluminium-hydroxide from Bayer liquor where the AHSSP presents crystallization agent (seed). The crystallization process is conducted to a certain Na2O/Al2O3 ratio, which corresponds to a satisfactory aluminium concentration in Bayer liquor. The crystallization process was conducted in laboratory crystallization vessels (2 dm3) equipped with a heater and stirrer. The crystallization temperature was 50±1°C and the concentration of aluminium-hydroxide as crystallization agent (seed) was 15, 20 and 30g/l. The concentration of Al, Na, and Zn in Bayer liquor and solid crystallization product (aluminium hydroxide as seed and aluminium hydroxide from Bayer liquor) was analysed by using ICP-OES (Specto Genesis) and AAS (Shimadzu AA7000). The particle size of the obtained solid crystallization product was analysed by Cilas 1090, laser particle size analyser. The specific surface area was determined by using Gemini VII, whereas the pore structure was analysed by using Mercury intrusion porosimetry (Carlo Erba Porosimeter 2000). The obtained results show that the per cent of removed Zn compounds was above 80 for 2h, whereas Al concentration decreased slightly less than 20% for the same time. Structural analysis is shown, that particle size and pore diameter were increased, whereas the specific surface area was decreased. For this reason, the possibility of using the aluminium-hydroxide as a product of this process, without structural modification, is maximally two times. Keywords: Zn-compounds, crystallization, alumina, and structural properties.",
publisher = "Association of Technology Engineers of Republic of Srpska",
journal = "Proceedings - XII Conference of Chemists, Technologists and Environmentalists of Republic of Srpska",
title = "Zinc removal from Bayer liquor by using aluminium hydroxide with specific structural properties as crystallization agent",
pages = "155-158",
url = "https://hdl.handle.net/21.15107/rcub_cer_3771"
}

Oljača, Đ., Milovanović, B., Pavlović, S., Smiljanić, R., Obrenović, Z.,& Filipović, R.. (2018). Zinc removal from Bayer liquor by using aluminium hydroxide with specific structural properties as crystallization agent. in Proceedings - XII Conference of Chemists, Technologists and Environmentalists of Republic of Srpska
Association of Technology Engineers of Republic of Srpska., 155-158.
https://hdl.handle.net/21.15107/rcub_cer_3771

Oljača Đ, Milovanović B, Pavlović S, Smiljanić R, Obrenović Z, Filipović R. Zinc removal from Bayer liquor by using aluminium hydroxide with specific structural properties as crystallization agent. in Proceedings - XII Conference of Chemists, Technologists and Environmentalists of Republic of Srpska. 2018;:155-158.
https://hdl.handle.net/21.15107/rcub_cer_3771 .

Oljača, Đurđa, Milovanović, Biljana, Pavlović, Stefan, Smiljanić, Radenko, Obrenović, Zoran, Filipović, Radislav, "Zinc removal from Bayer liquor by using aluminium hydroxide with specific structural properties as crystallization agent" in Proceedings - XII Conference of Chemists, Technologists and Environmentalists of Republic of Srpska (2018):155-158,
https://hdl.handle.net/21.15107/rcub_cer_3771 .