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Use of boron mining waste as an alternative to boric acid (H3BO3) in opaque frit production
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Use of boron mining waste as an alternative to boric acid (H3BO3) in opaque frit production ⁎
Bugra Ciceka,b, , Emirhan Karadaglia,b, Fatma Dumanc a
Department of Metallurgy and Material Science Engineering, Yildiz Technical University, Esenler, Istanbul, Turkey Boron Based Materials and Advanced Chemicals Research and Application Center, Koc University, Sarıyer, Istanbul, Turkey c Eczacibasi Building Products Company, VitrA Innovation Center, Bozuyuk, Bilecik, Turkey b
A R T I C LE I N FO
A B S T R A C T
Keywords: Borates Waste disposal Low temperature Glaze
Colemanite (CaO·3B2O3·5H2) enrichment waste material from mines was employed as an alternative to boric acid (H3BO3) for producing opaque matt frits. The aim of the study was to reduce boric acid consumption and to substitute boron-containing waste material for H3BO3 used for frit production. Laboratory and pilot-scale production was carried out based on frit production methods currently used in the ceramic industry. The frits were then used to produce commercial glossy opaque glazes using existing fabrication and sintering processes with amounts ranging between 16 and 31 wt%. The fabricated glazes successfully passed EN ISO 10545 testing, exhibiting desirable surface abrasion, chemical resistance, thermal shock resistance, and staining characteristics.
1. Introduction The world's largest boron deposits are located in the West Anatolia region of Turkey, accounting for 72% (851 Mt) of the world's total deposits [1,2]. Because of such activity, 2 Mt of refined boron products and 1.78 Mt of chemical boron products are produced annually in the region [3]. Owing to the high production capacity of these mines, 400,000 t of various boron-containing waste products are produced every year from extraction, refining and enrichment processes [4]. Because of the high amounts of B2O3 present in these waste products, various strategies are being developed to utilize these materials in the ceramic and glass-ceramics industries [5–14]. However, utilizing this waste at the industrial scale remains a challenge. Frits are an essential ceramic component consisting of various highly amorphous materials. Frit production involves three primary steps: raw material blending, firing at elevated temperatures (1400 °C), and subsequent quenching to room temperature in water. Quenching is essential for the development of the amorphous phase, and the fabricated frits exhibit an amorphous structure consisting of ceramic nuclei. The frit is the most important constituent of enamels and glazes, accounting for approximately 80–90% of the total components. The use of B2O3 in the production of frits and indirectly in the
⁎
production of glazes has numerous positive effects from both technical and visual perspectives. B2O3 is a flux which does not increase the thermal expansion coefficient of the overall material, in contrast to other fluxes such as alkaline and earth alkaline materials. The thermal expansion characteristics of glazes are very important, as a glaze is typically applied as the final layer on a tile's surface; if the thermal expansion coefficient of the glaze is not within the desired range, the desired surface coverage will not be achieved. Furthermore, B2O3 is highly effective for network formation and improves the chemical resistance and mechanical durability of a ceramic material. It has also been reported that B2O3 increases the scratch resistance of glazes [15,16]. Because boric acid can yield high-purity B2O3 in large quantities, it is commonly used as the B2O3 source for frit production as well as in other B2O3-consuming industries. Given the large amounts of boron-containing waste produced from the mining industry and the high B2O3 content of this waste (16–31%), utilizing this waste as a B2O3 source and an alternative to boric acid for frit production merits consideration. In this study, colemanite enrichment wastes from Bigadiç and Bandırma were used as a source of B2O3 to produce opaque frits using a ZrCMS glass-ceramic system. The waste was added to the starting composition based on the Seger formula for the standard composition,
Corresponding author at: Department of Metallurgy and Material Science Engineering, Yildiz Technical University, Esenler, Istanbul, Turkey. E-mail address: [email protected] (B. Cicek).
https://doi.org/10.1016/j.ceramint.2018.05.031 Received 13 March 2018; Received in revised form 26 April 2018; Accepted 5 May 2018 0272-8842/ © 2018 Published by Elsevier Ltd.
Please cite this article as: Cicek, B., Ceramics International (2018), https://doi.org/10.1016/j.ceramint.2018.05.031
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Table 1 Chemical compositions of colemanite enrichment waste samples from Bandırma (wt%). Oxide (wt%)
A1
A2
A3
A4
A5
A6
SiO2 Al2O3 Fe2O3 B2O3 CaO MgO K2O Na2O P2O5 SnO2 Cr2O3 BaO a L.O.I.
10.25 0.34 0.19 20.41 34.18 3.70 0.04 0.17 0 0 0 0 30.17
19.81 0.72 0.33 18.41 25.34 8.96 0.13 0.57 0.04 0 0 0.23 24.11
16.98 0.57 0.24 21.20 23.31 8.82 0.12 1.34 0.01 0 0 0 24.97
17.13 0.31 0.31 16.37 31.28 7.32 0.17 0 0.03 0 0 0 25.43
0.39 0.11 0.13 29.52 52.75 0.80 0 0.81 0.01 0 0 0 14.68
1.28 0.63 0.13 31.11 33.41 0.60 0.03 0.90 0.01 0.338 0.03 0 30.74
a
LOI: Loss on Ignition. Fig. 3. XRD patterns of MOF1, MOF1-A1, MOF1-A2, MOF1-A3 and MOF1-A4.
Table 2 Seger tables for MOF1, MOF1-A1, MOF1-A2, MOF1-A3, MOF1-A4, MOF1-A5 and MOF1-A6 frits.
Seger oxide content (% mol)
Seger oxide ratio B O 2 3 Seger molar value BW content in compositions
a
Oxide
MOF1
MOF1-A1
MOF1-A2
MOF1-A3
MOF1-A4
MOF1-A5
MOF1-A6
R O (Na O, K
1.17 35.5 6.60 56.73 100 45.587 0.910 0.146 0 0.00
1.18 35.80 6.61 56.44 100 44.066 0.908 0.144 0.144 24.40
1.28 36.23 6.56 55.93 100 42.101 0.866 0.140 0.140 27.05
1.49 35.69 6.57 56.26 100 43.243 0.912 0.142 0.142 23.50
1.14 35.44 6.77 56.65 100 39.88 0.9 0.145 0.145 16.00
1.3 35.75 6.55 56.4 100 44.725 0.901 0.143 0.143 17.50
1.32 35.4 6.64 56.7 100 42.987 0.905 0.145 0.145 31.00
2 2 2°) RO (CaO, MgO, ZnO) R B , Al 2°3 ( 2°3 2°3, Fe2°3) RO 2 (SiO2, ZrO2) TOTAL SiO /Al 2 2°3 MgO/CaO Total B 2°3 aB 2°3 (BW) BW (wt%)
B2O3 (BW), boron trioxide derived from boron waste.
to ensure that there were no rheological irregularities. The waste-based frits were then used to produce glaze slips, and the resulting glazes were applied to tile surfaces that were subsequently characterized.
Fig. 4. XRD patterns of MOF1, MOF1-A5, and MOF1-A6.
Fig. 1. Flow of fabrication of opaque frits.
Preparation of glaze composition (frit, CMC, kaolin, STTP, and water)
Milling and screening (14 min, 45 m)
Application on tiles (drawing method)
Glazing & characterization
Firing (1145 oC, 36 min)
Drying (100 oC)
Fig. 2. Flow of process for producing glazes. Fig. 5. XRD patterns of BOG, BOG-A3, and BOG-A5 glazes. 2
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Fig. 6. SEM images of surfaces of (a) MOF1, (b) MOF1-A1, (c) MOF1-A2, (d) MOF1-A3, and (e) MOF1-A4.
2. Experimental procedures
as mining waste, while samples A5 and A6 were taken from the Bandırma enrichment plant, and are thus classed as enrichment waste. The complexity of the A5 and A6 samples was low but their B2O3 content is high, because they are enrichment waste. Based on their compositions, particularly their CaO and MgO contents, samples A5 and A6 were considered the most suitable for use in this study, owing to their high
Before use, the waste samples were subjected to chemical analysis to determine their initial compositions. The chemical compositions of waste samples A1 to A6 are listed in Table 1. Samples A1, A2, A3, and A4 were taken from the Bigadiç mining plant, and are therefore classed
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Fig. 7. SEM images of surfaces of (a) MOF1, (b) MOF1-A5, and (c) MOF1-A6.
material needed, providing a greater economic benefit relative to that of the standard MOF1 composition. The dolomite usage was reduced by 64% in MOF1-A1, 46.3% in MOF1-A2, 40.66% in MOF1-A3, 72.13% in MOF1-A4, 41.3% in MOF1-A5, and 66.67% in MOF1-A6.
B2O3 content and low compositional complexity. The possibility of using this waste as an alternative to boric acid for producing opaque frits was explored using the Seger formula for a standard composition. The oxide ratios for the standard frit composition, labeled as MOF1, were calculated and a Seger table corresponding to MOF1 was formed. New compositions were then prepared, their raw material distributions calculated, and their Seger ratios determined. The new compositions were labeled in a manner similar to that used for the standard frit composition; the names of the new compositions also contained the name of the waste sample on which they were based (e.g., MOF1-A6). Table 2 compares these values with those of MOF1. The Seger tables were arranged by grouping the oxides as R2O (Na2O, K2O), RO (CaO, MgO, ZnO), R2O3 (B2O3, Al2O3, Fe2O3), RO2 (ZrO2, SiO2) and by listing their ratios (MgO/CaO) and (SiO2/Al2O3). Based on comparing the values listed in Table 2, the oxide ratios of MOF1 and the waste-containing compositions are similar. This similarity was achieved by partially removing the dolomite (CaO and MgO source) from the compositions, since a large amount of CaO was added to the compositions through the addition of boron waste. This also proved that the use of boron waste can help decrease the amount of raw
3. Materials and methods The waste-containing mixtures were processed as shown in Fig. 1 to produce frits. All the raw materials were dried in a drying oven (FN 400, Nüve) at 100 °C for 24 h to remove moisture, then weighed and blended in the desired proportions. These blends were then placed in porcelain crucibles that contained a large amount of alumina and were subjected to melting for 1 h at a peak temperature of 1450 °C to produce opaque matt frits, using a laboratory-type furnace (Protherm PLF Series, TR). The molten blend was quenched in water to room temperature, and the resulting frits were dried in an oven at 100 °C. The waste-containing frits were then used for glaze production, as shown in Fig. 2. First, 92 g of a frit, 8 g of kaolin, 0.1 g of carboxymethyl cellulose (CMC), 0.4 g of sodium tripolyphosphate (STPP), and 35 mL of water were mixed and milled in a ball mill (Modular System SD Series,
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Fig. 8. SEM images of surfaces of (a) MOF1, (b) MOF1-A1, (c) MOF1-A2, (d) MOF1-A3, and (e) MOF1-A4.
2230) at 1145 °C for 36 min. The final layer on a tile's surface is termed as the “glaze.” The prepared glazes were designated using the frit employed in their production (e.g. MOF1-A3 glaze). Waste-containing frits were also employed in the production of bright opaque glazes. Different groups of frits can be mixed to yield a
Ceramic Instruments Rapid Mills) for 14 min. The milled mixture was then passed through a 45-μm sieve, and the obtained slip was termed as a “glaze suspension.” The produced glaze suspensions were applied to sintered wall tiles by a drawing method and left to dry at 100 °C. Once dry, the tiles were fired in an industrial roller furnace (SACMI-FMS
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Fig. 9. SEM images of surfaces of (a) MOF1, (b) MOF1-A5, and (c) MOF1-A6.
glazes were coated with a Au/Pd alloy to ensure high conductivity. For scanning electron microscopy (SEM)/EDX analysis, an acceleration voltage of 20 kV was used at working distances of 9.5 and 10 mm. The colors values (L*, a, and b) of the specimens were determined using an “X-rite” color identifier. The surface roughness values of the specimens were measured using a roughness analyzer (KR 100, Ceramic Instruments), while their brightness values were determined using a glass meter (Multi Gloss 268 Plus, Konica Minolta). To observe the sintering behaviors of the frits, a heat microscope (ODHT-HSM 1600/ 50, Misura 3.32) was used. The sintering, softening, sphere, half-sphere, and melting temperatures of the frits were determined by heating the frit samples to 400 °C at a rate of 30 °C/min and to 1400 °C at a rate of 10 °C/min. To determine the crystallization temperatures of the frits, differential thermal analysis (DTA) (Netzsch STA 409 PC) was performed; during the analyses, the frits were heated to 1200 °C at a rate of 10 °C/min. The ISO 10545 standard defines the tests used on traditional ceramic tiles and glazes. According to this standard, chemical resistance, thermal shock resistance, staining resistance, Mohs (surface) hardness, surface abrasion resistance, and crazing resistance tests were
bright opaque glaze, specifically bright and matt opaque frits. The main reason for using the matt opaque frits is to overcome the boiling problem that is associated with their high softening temperatures. Wastecontaining MOF1-A3 and MOF1-A5 frits were employed as matt opaque frits, given their similar surface properties to a standard MOF1 frit. The standard bright opaque glaze was labeled “BOG” and those glazes incorporating MOF1-A3 and MOF1-A5 were additionally labeled using the code for the boron waste (e.g., BOG-A3). The glaze application was performed in the same way as described in Fig. 2 but with a slight difference in firing process, which was carried out at a peak temperature of 1215 °C for 43 min. To determine the chemical compositions of the frits, X-ray fluorescence (XRF) measurements and energy-dispersive X-ray spectroscopy (EDX) were performed. The voltage and current values for Ca and K were 40 kV and 75 mA, respectively, while those for Cl, S, P, Si, Al, Mg, Na, F, and B were 30 kV and 100 mA. To determine the mineralogical structures of the glazes, X-ray diffraction (XRD) analyses (Rigaku RINT 2000) were performed using an acceleration voltage of 40 kV and a current of 30 mA. The specimens were inspected for 2θ values of 10–70° at a scanning rate of 2°/min. Prior to the microstructural analysis, the
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Fig. 10. SEM images of cross-sections of (a) MOF1, (b) MOF1-A1, (c) MOF1-A2, (d) MOF1-A3, and (e) MOF1-A4.
present in the waste-containing frits, similar to a standard MOF1 glaze. The width of the peak of the amorphous phase was higher for the wastecontaining frits than for MOF1, given that the elements present in the waste tend to form compounds with an amorphous structure (CaO and B2O3). In the pattern for the standard MOF1 glaze, the intensity of the peak related to the diopside crystals is higher than that of the peak
conducted on the obtained BOG-A3 and BOG-A5 bright opaque glazes. 4. Results and discussion The XRD patterns shown in Fig. 3 and Fig. 4 indicate that small amounts of diopside (MgCaSi2O6) and zircon (ZrSiO4) crystals were
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Fig. 11. SEM images of cross-sections of (a) MOF1, (b) MOF1-A5, and (c) MOF1-A6.
Figs. 10 and 11 show cross-sectional SEM images of the glazes including waste as well as that of MOF1, while Figs. 12 and 13 shows higher-magnification images of the areas marked by the yellow lines in Figs. 10 and 11. The pores in the standard glaze are interconnected, while those in the newly developed glazes are not, and the latter are smaller than the pores in the standard glaze. As shown in Figs. 14 and 15, the size, shape, and distribution of the crystals in all the bright opaque glazes are very similar, independent of the imaged area. EDX analysis of the crystals also proved the presence of zircon crystals in the structures. The sintering curves (Figs. 16 and 17) of the frits developed using the waste show that their softening and melting temperatures are lower than those of a standard frit (Table 3). The critical temperatures of the MOF1-A4 frit, which produced the brightest glaze, are the lowest. This observed decrease in sintering temperature can be explained based on the fluxing effects of both CaO and B2O3. Together, they create a more effective flux than the standard composition, resulting in a decrease of the sintering temperature. Further, as shown in the DTA curves in Figs. 18 and 19, the crystallization temperatures of the frits are similar (around 950 °C). However, the crystallization peak of the standard MOF1 frit is sharper and of a higher intensity than those of the waste-containing frits. The CaO and
attributable to the zircon crystals. However, in the pattern for MOF1A5, the intensities of the two peaks are similar. Furthermore, the degree of crystallization of the waste-containing frits was lower owing to the presence of the glass-forming fluxes, as evidenced by the low intensity of the crystallization peaks. XRD analysis of the surfaces of BOG-A3 and BOG-A5 (Fig. 5) showed that they only contained zircon crystals in addition to the amorphous phase, in the same manner as BOG. Mineralogical analysis proved that the addition of boron waste to the frit composition has no undesired effect on the type of crystals formed on the surface. Figs. 6 and 7 show SEM images of the surfaces of waste-containing glazes as well as that of the MOF1 glaze, while Figs. 8 and 9 shows higher-magnification images of the areas marked with the dotted lines in Figs. 6 and 7. The produced glazes do not have highly porous surfaces such as that of the standard MOF1 glaze. The shape and density of the pores can be attributed to the effect of the viscous sintering process. At temperatures higher than the glass-transition temperature (approximately 1100 °C) [17], the viscosity of the frits decreases. Furthermore, at higher temperatures, the large amount of Ca present in the structure starts to act as a flux along with B2O3. Owing to these fluxes, the extent of sintering and densification increases, leading to smaller pores [18–20].
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Fig. 12. SEM images of cross-sections of (a) MOF1, (b) MOF1-A1, (c) MOF1-A2, (d) MOF1-A3, and (e) MOF1-A4.
differences are caused by the different amounts of metal oxides present in the waste compositions, especially fluxing oxides. As determined from the DTA curves (Fig. 21), the sintering mechanism stopped between 950 and 980 °C due to the exothermic peak corresponding to the formation of zircon crystals in the structures. The formation of zircon crystals increased the viscosity of the glaze and blocked the bulk flow,
B2O3 present in the waste-derived frits cause viscous sintering, which leads to the formation of an amorphous structure. As a result, the crystallization peaks of the newly developed frits are wider and lower in intensity [18–20]. The sintering curves (Fig. 20) of BOG-A3 and BOG-A5 show that their critical temperatures are close to that of BOG. The slight
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Fig. 13. SEM images of cross-sections of (a) MOF1, (b) MOF1-A5, and (c) MOF1-A6.
containing bright opaque glazes are very similar to the standard BOG. BOG-A3 exhibits a greater brightness than BOG-A5. The results of the applied ISO 10545 tests are listed in Table 6. The waste-containing bright opaque glazes exhibit very similar characteristics to those of a standard glaze. Regarding the decorative use of the glazes and areas in which they are likely to be applied, staining resistance and chemical resistance are important both visually and technically. The test results showed that the waste-containing glazes are well suited to such applications.
which a caused a break in the sintering. Once the system reached 1070 °C (the softening point), the glaze became viscous again and the sintering continued. The endothermic peak around 1200 °C can be explained as an indication of the melting of zircon crystals in the amorphous (glassy) phase. Images of the final glaze layers formed by firing are shown in Fig. 22. An image of the standard MOF1 glaze is also shown for comparison. The results of the color, surface roughness, and brightness analyses are listed in Table 4. The brightness and roughness values for MOF1-A3 and MOF1-A5 are very similar to those of the standard glaze, while the others are brighter and smoother than the standard glaze. The seven glazes could be arranged in order of brightness and roughness as follows: MOF1-A4 > MOF1-A2 > MOF1-A1 > MOF1-A6 > MOF1A3 > MOF1-A5 > MOF1 and MOF1-A5 > MOF1 > MOF1-A6 > MOF1-A1 > MOF1-A2 > MOF1-A4. This also shows that there is an inverse relationship between a surface's roughness and its brightness. Table 5 compares color and brightness values of BOG-A3 and BOG-A5 with those of BOG. As expected, the visual properties of the waste-
5. Conclusions In the present study, colemanite mining and enrichment waste from the Bigadiç and Bandırma plants was successfully used as an alternative source of B2O3, in place of boric acid used in the industrial production of opaque matt frits and bright opaque glazes in the ceramics industry. The obtained final product could be applied to conventional tile production even at lower sintering temperatures. A low CaO content in transparent frits allowed for the limited addition of waste. This method
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Fig. 14. (a), (d), (g) SEM (backscattered electron) images of surfaces of BOG, BOG-A3, and BOG-A5. (b), (e), (h) SEM (backscattered electron) images of marked areas in (a), (d), and (g) at higher magnification(c), (f), (ı) EDX analysis of dotted crystals in (b), (e), and (h).
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Fig. 15. (a), (d), (g) SEM (backscattered electron) images of cross-sections of BOG, BOG-A3 and BOG-A5. (b), (e), (h) SEM (backscattered electron) images of the marked areas in (a), (d) and (g) in higher magnification (c), (f), (ı) EDX analysis of dotted crystals in (b), (e) and (h).
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Fig. 16. Results of thermal analysis of frits using heat microscope.
Fig. 17. Results of thermal analysis of frits using heat microscope.
Table 3 Results of thermal analysis of developed frits. FRIT
Sintering temperature °C
Softening temperature °C
Melting temperature °C
MOF1 MOF1-A1 MOF1-A2 MOF1-A3 MOF1-A4 MOF1-A5 MOF1-A6
838 822 820 828 802 818 812
1200 1170 1172 1188 1134 1204 1194
1252 1218 1212 1224 1194 1236 1224
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Fig. 18. Results of DTA analysis of frits.
Fig. 19. Results of DTA analysis of frits.
Fig. 20. Results of thermal analysis of bright opaque glazes using heat microscope.
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Fig. 21. Results of DTA analysis of bright opaque frits.
Acknowledgements
also reduced the sintering temperature but prevented the waste from being used as a complete substitute for boric acid [14]. The resulting bright opaque glaze compositions successfully passed EN ISO 10545 test requirements, providing adequate levels of surface abrasion, chemical resistance, thermal shock resistance, and staining characteristics. The present study indicates that the waste held near enrichment plants for further treatment can be employed as a valuable raw material for ceramics, and can contribute to sustainable production in the ceramics industry.
This study was funded jointly by the Eczacibasi Group (A15w06) and the National Boron Institute Turkey (BOREN) (2015-31-07-15002), with the aim of identifying a method of utilizing boron waste for ceramics production in a sustainable manner.
Fig. 22. Digital photographs of MOF1, MOF1-A5, and MOF1-A6 glazes, applied to tile surfaces.
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Table 4 Color, brightness, and roughness of developed glazes. Glaze
MOF1 MOF1-A1 MOF1-A2 MOF1-A3 MOF1-A4 MOF1-A5 MOF1-A6
Color
Brightness
Roughness
L*
a*
b*
20°
60°
80°
µm
92.47 89 89.28 89.3 88.31 90.94 90.45
− 0.1 0.4 0.6 0.72 0.6 0.22 0.32
0.76 1.45 2.24 2.5 2.27 1.4 1.64
1.1 2.4 4.1 1.3 6.9 1.1 1.4
2.4 16.2 23.8 5.2 33.2 2.7 6.2
2.4 38.9 55.8 6.9 64.1 2.9 7.2
18.72 4.97 4.02 12.19 2.21 19.35 10.13
Table 5 Color and brightness values of bright opaque glazes. Glaze
BOG BOG-A3 BOG-A5
Color
Brightness
L*
a*
b*
20°
60°
80°
92.05 91.72 91.53
− 0.78 − 0.76 − 0.76
2.28 2.77 2.91
75 72.5 75
93.4 91.1 90.9
94.3 96.2 93.5
BOG
BOG-A3
BOG-A5
3 (1500 rpm)
3 (1500 rpm)
3 (1500 rpm)
1 day
GA
GA
GA
1 day
GLA
GLA
GLA
4 days 4 days 1 day
GLA GLC GLA
GLA GLC GLA
GLA GLC GLA
4 days 4 days 4 days
GHA GHC GHA
GHA GHC GHA
GHA GHC GHA
GA Suitable
GA Suitable
GA Suitable
5 5 5 5 5 5 5 5 4 Suitable
5 5 5 5 5 5 5 5 4 Suitable
5 5 5 5 5 5 5 5 4 Suitable
Table 6 ISO 10545 test results for BOG, BOG-A3, and BOG-A5. Test Surface Abrasion Value (PEI) (TS EN ISO 10545–7) Chemical Resistance (ISO 10545–13)
Description
House Chemicals Swimming Pool Salts Low-Concentration Acids and Alkalis High-Concentration Acids and Alkalis
Cement Joint Cleaner Thermal Shock Resistance (ISO 10545–9) Staining Tests (ISO 10545–14)
Amonium Chloride (100 g/l) Sodium Hypochloride (20 mg/l) HCl (%3) KOH (30 g/l) Citric Acid (100 g/l) HCl (%18) KOH (100gr/l) Lactic Acid − 5%
Iron Oxide Olive Oil Alcohol Iodide Methylene Blue Potassium Permanganate Black Joint Filler Pencil Test Shoe Mark
Mohs (Surface Hardness) Crazing Resistance
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ceramics prepared by low temperature sintering/sinter-crystallization, Adv. Appl. Ceram. Struct. Funct. Bioceram. 115 (2016) 427–434. A. Christogerou, T. Kavas, Y. Pontikes, C. Rathossi, G.N. Angelopoulos, Evolution of microstructure, mineralogy and properties during firing of clay-based ceramics with borates, Ceram. Int. 36 (2010) 567–575. A. Christogerou, T. Kavas, Y. Pontikes, S. Koyas, Y. Tabak, G.N. Angelopoulos, Use of boron wastes in the production of heavy clay ceramics, Ceram. Int. 35 (2009) 447–452. S. Kurama, A. Kara, H. Kurama, Investigation of borax waste behavior in tile production, J. Eur. Ceram. Soc. 27 (2007) 1715–1720. A. Olgun, Y. Erdogan, Y. Ayhan, B. Zeybek, Development of ceramic tiles from coal fly ash and tincal ore waste, Ceram. Int. 31 (2005) 153–158. S. Kurama, A. Kara, H. Kurama, The effect of boron waste in phase and microstructural development of a terracotta body during firing, J. Eur. Ceram. Soc. 26 (2006) 755–760.
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[17] Tony Hansen, CaO, Calcium Oxide, Calcia, (Accessed on May 30, 2017) 〈https:// digitalfire.com/4sight/oxide/cao.html〉. [18] K. Shinagawa, Micromechanical modelling of viscous sintering and a constitutive equation with sintering stress, Comput. Mater. Sci. 13 (1999) 276. [19] Hadrian Djohari, Jorge I. Martínez-Herrera, Jeffrey J. Derby, Transport mechanisms and densification during sintering: I. Viscous flow versus vacancy diffusion, Chem. Eng. Sci. 64 (2009) 3799–3809. [20] S. Somiya, Sintering of Ceramics, Lutgard C. De Jonghe, Mohamed N. Rahaman, Handbook of Advanced Ceramics, 2003.
[13] Taner Kavas, Use of boron waste as a fluxing agent in production of red mud brick, Build. Environ. 41 (2006) 1779–1783. [14] F. Duman, T. Yagyemez, E. Karadagli, B. Cicek, Utilization of Bandırma colemanite enrichment wastes in the production of transparent Frits, Mater. Today.: Proc. 00 (2017) 2214–7853. [15] A. Tunali, E. Ozela, S. Turan, ‘’Production and characterization of granulated frit to achieve anorthite based glass–ceramic glaze’’, J. Eur. Ceram. Soc. 35 (2015) 1089–1095. [16] Borates in enamels and glazes'’ (Accessed on May 30, 2017) 〈http://www.borax. com/wp-content/uploads/2016/07/euf-borates-boratesinglazesandenamels.pdf〉.
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Contents lists available at ScienceDirect
Ceramics International journal homepage: www.elsevier.com/locate/ceramint
Use of boron mining waste as an alternative to boric acid (H3BO3) in opaque frit production ⁎
Bugra Ciceka,b, , Emirhan Karadaglia,b, Fatma Dumanc a
Department of Metallurgy and Material Science Engineering, Yildiz Technical University, Esenler, Istanbul, Turkey Boron Based Materials and Advanced Chemicals Research and Application Center, Koc University, Sarıyer, Istanbul, Turkey c Eczacibasi Building Products Company, VitrA Innovation Center, Bozuyuk, Bilecik, Turkey b
A R T I C LE I N FO
A B S T R A C T
Keywords: Borates Waste disposal Low temperature Glaze
Colemanite (CaO·3B2O3·5H2) enrichment waste material from mines was employed as an alternative to boric acid (H3BO3) for producing opaque matt frits. The aim of the study was to reduce boric acid consumption and to substitute boron-containing waste material for H3BO3 used for frit production. Laboratory and pilot-scale production was carried out based on frit production methods currently used in the ceramic industry. The frits were then used to produce commercial glossy opaque glazes using existing fabrication and sintering processes with amounts ranging between 16 and 31 wt%. The fabricated glazes successfully passed EN ISO 10545 testing, exhibiting desirable surface abrasion, chemical resistance, thermal shock resistance, and staining characteristics.
1. Introduction The world's largest boron deposits are located in the West Anatolia region of Turkey, accounting for 72% (851 Mt) of the world's total deposits [1,2]. Because of such activity, 2 Mt of refined boron products and 1.78 Mt of chemical boron products are produced annually in the region [3]. Owing to the high production capacity of these mines, 400,000 t of various boron-containing waste products are produced every year from extraction, refining and enrichment processes [4]. Because of the high amounts of B2O3 present in these waste products, various strategies are being developed to utilize these materials in the ceramic and glass-ceramics industries [5–14]. However, utilizing this waste at the industrial scale remains a challenge. Frits are an essential ceramic component consisting of various highly amorphous materials. Frit production involves three primary steps: raw material blending, firing at elevated temperatures (1400 °C), and subsequent quenching to room temperature in water. Quenching is essential for the development of the amorphous phase, and the fabricated frits exhibit an amorphous structure consisting of ceramic nuclei. The frit is the most important constituent of enamels and glazes, accounting for approximately 80–90% of the total components. The use of B2O3 in the production of frits and indirectly in the
⁎
production of glazes has numerous positive effects from both technical and visual perspectives. B2O3 is a flux which does not increase the thermal expansion coefficient of the overall material, in contrast to other fluxes such as alkaline and earth alkaline materials. The thermal expansion characteristics of glazes are very important, as a glaze is typically applied as the final layer on a tile's surface; if the thermal expansion coefficient of the glaze is not within the desired range, the desired surface coverage will not be achieved. Furthermore, B2O3 is highly effective for network formation and improves the chemical resistance and mechanical durability of a ceramic material. It has also been reported that B2O3 increases the scratch resistance of glazes [15,16]. Because boric acid can yield high-purity B2O3 in large quantities, it is commonly used as the B2O3 source for frit production as well as in other B2O3-consuming industries. Given the large amounts of boron-containing waste produced from the mining industry and the high B2O3 content of this waste (16–31%), utilizing this waste as a B2O3 source and an alternative to boric acid for frit production merits consideration. In this study, colemanite enrichment wastes from Bigadiç and Bandırma were used as a source of B2O3 to produce opaque frits using a ZrCMS glass-ceramic system. The waste was added to the starting composition based on the Seger formula for the standard composition,
Corresponding author at: Department of Metallurgy and Material Science Engineering, Yildiz Technical University, Esenler, Istanbul, Turkey. E-mail address: [email protected] (B. Cicek).
https://doi.org/10.1016/j.ceramint.2018.05.031 Received 13 March 2018; Received in revised form 26 April 2018; Accepted 5 May 2018 0272-8842/ © 2018 Published by Elsevier Ltd.
Please cite this article as: Cicek, B., Ceramics International (2018), https://doi.org/10.1016/j.ceramint.2018.05.031
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Table 1 Chemical compositions of colemanite enrichment waste samples from Bandırma (wt%). Oxide (wt%)
A1
A2
A3
A4
A5
A6
SiO2 Al2O3 Fe2O3 B2O3 CaO MgO K2O Na2O P2O5 SnO2 Cr2O3 BaO a L.O.I.
10.25 0.34 0.19 20.41 34.18 3.70 0.04 0.17 0 0 0 0 30.17
19.81 0.72 0.33 18.41 25.34 8.96 0.13 0.57 0.04 0 0 0.23 24.11
16.98 0.57 0.24 21.20 23.31 8.82 0.12 1.34 0.01 0 0 0 24.97
17.13 0.31 0.31 16.37 31.28 7.32 0.17 0 0.03 0 0 0 25.43
0.39 0.11 0.13 29.52 52.75 0.80 0 0.81 0.01 0 0 0 14.68
1.28 0.63 0.13 31.11 33.41 0.60 0.03 0.90 0.01 0.338 0.03 0 30.74
a
LOI: Loss on Ignition. Fig. 3. XRD patterns of MOF1, MOF1-A1, MOF1-A2, MOF1-A3 and MOF1-A4.
Table 2 Seger tables for MOF1, MOF1-A1, MOF1-A2, MOF1-A3, MOF1-A4, MOF1-A5 and MOF1-A6 frits.
Seger oxide content (% mol)
Seger oxide ratio B O 2 3 Seger molar value BW content in compositions
a
Oxide
MOF1
MOF1-A1
MOF1-A2
MOF1-A3
MOF1-A4
MOF1-A5
MOF1-A6
R O (Na O, K
1.17 35.5 6.60 56.73 100 45.587 0.910 0.146 0 0.00
1.18 35.80 6.61 56.44 100 44.066 0.908 0.144 0.144 24.40
1.28 36.23 6.56 55.93 100 42.101 0.866 0.140 0.140 27.05
1.49 35.69 6.57 56.26 100 43.243 0.912 0.142 0.142 23.50
1.14 35.44 6.77 56.65 100 39.88 0.9 0.145 0.145 16.00
1.3 35.75 6.55 56.4 100 44.725 0.901 0.143 0.143 17.50
1.32 35.4 6.64 56.7 100 42.987 0.905 0.145 0.145 31.00
2 2 2°) RO (CaO, MgO, ZnO) R B , Al 2°3 ( 2°3 2°3, Fe2°3) RO 2 (SiO2, ZrO2) TOTAL SiO /Al 2 2°3 MgO/CaO Total B 2°3 aB 2°3 (BW) BW (wt%)
B2O3 (BW), boron trioxide derived from boron waste.
to ensure that there were no rheological irregularities. The waste-based frits were then used to produce glaze slips, and the resulting glazes were applied to tile surfaces that were subsequently characterized.
Fig. 4. XRD patterns of MOF1, MOF1-A5, and MOF1-A6.
Fig. 1. Flow of fabrication of opaque frits.
Preparation of glaze composition (frit, CMC, kaolin, STTP, and water)
Milling and screening (14 min, 45 m)
Application on tiles (drawing method)
Glazing & characterization
Firing (1145 oC, 36 min)
Drying (100 oC)
Fig. 2. Flow of process for producing glazes. Fig. 5. XRD patterns of BOG, BOG-A3, and BOG-A5 glazes. 2
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Fig. 6. SEM images of surfaces of (a) MOF1, (b) MOF1-A1, (c) MOF1-A2, (d) MOF1-A3, and (e) MOF1-A4.
2. Experimental procedures
as mining waste, while samples A5 and A6 were taken from the Bandırma enrichment plant, and are thus classed as enrichment waste. The complexity of the A5 and A6 samples was low but their B2O3 content is high, because they are enrichment waste. Based on their compositions, particularly their CaO and MgO contents, samples A5 and A6 were considered the most suitable for use in this study, owing to their high
Before use, the waste samples were subjected to chemical analysis to determine their initial compositions. The chemical compositions of waste samples A1 to A6 are listed in Table 1. Samples A1, A2, A3, and A4 were taken from the Bigadiç mining plant, and are therefore classed
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Fig. 7. SEM images of surfaces of (a) MOF1, (b) MOF1-A5, and (c) MOF1-A6.
material needed, providing a greater economic benefit relative to that of the standard MOF1 composition. The dolomite usage was reduced by 64% in MOF1-A1, 46.3% in MOF1-A2, 40.66% in MOF1-A3, 72.13% in MOF1-A4, 41.3% in MOF1-A5, and 66.67% in MOF1-A6.
B2O3 content and low compositional complexity. The possibility of using this waste as an alternative to boric acid for producing opaque frits was explored using the Seger formula for a standard composition. The oxide ratios for the standard frit composition, labeled as MOF1, were calculated and a Seger table corresponding to MOF1 was formed. New compositions were then prepared, their raw material distributions calculated, and their Seger ratios determined. The new compositions were labeled in a manner similar to that used for the standard frit composition; the names of the new compositions also contained the name of the waste sample on which they were based (e.g., MOF1-A6). Table 2 compares these values with those of MOF1. The Seger tables were arranged by grouping the oxides as R2O (Na2O, K2O), RO (CaO, MgO, ZnO), R2O3 (B2O3, Al2O3, Fe2O3), RO2 (ZrO2, SiO2) and by listing their ratios (MgO/CaO) and (SiO2/Al2O3). Based on comparing the values listed in Table 2, the oxide ratios of MOF1 and the waste-containing compositions are similar. This similarity was achieved by partially removing the dolomite (CaO and MgO source) from the compositions, since a large amount of CaO was added to the compositions through the addition of boron waste. This also proved that the use of boron waste can help decrease the amount of raw
3. Materials and methods The waste-containing mixtures were processed as shown in Fig. 1 to produce frits. All the raw materials were dried in a drying oven (FN 400, Nüve) at 100 °C for 24 h to remove moisture, then weighed and blended in the desired proportions. These blends were then placed in porcelain crucibles that contained a large amount of alumina and were subjected to melting for 1 h at a peak temperature of 1450 °C to produce opaque matt frits, using a laboratory-type furnace (Protherm PLF Series, TR). The molten blend was quenched in water to room temperature, and the resulting frits were dried in an oven at 100 °C. The waste-containing frits were then used for glaze production, as shown in Fig. 2. First, 92 g of a frit, 8 g of kaolin, 0.1 g of carboxymethyl cellulose (CMC), 0.4 g of sodium tripolyphosphate (STPP), and 35 mL of water were mixed and milled in a ball mill (Modular System SD Series,
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Fig. 8. SEM images of surfaces of (a) MOF1, (b) MOF1-A1, (c) MOF1-A2, (d) MOF1-A3, and (e) MOF1-A4.
2230) at 1145 °C for 36 min. The final layer on a tile's surface is termed as the “glaze.” The prepared glazes were designated using the frit employed in their production (e.g. MOF1-A3 glaze). Waste-containing frits were also employed in the production of bright opaque glazes. Different groups of frits can be mixed to yield a
Ceramic Instruments Rapid Mills) for 14 min. The milled mixture was then passed through a 45-μm sieve, and the obtained slip was termed as a “glaze suspension.” The produced glaze suspensions were applied to sintered wall tiles by a drawing method and left to dry at 100 °C. Once dry, the tiles were fired in an industrial roller furnace (SACMI-FMS
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Fig. 9. SEM images of surfaces of (a) MOF1, (b) MOF1-A5, and (c) MOF1-A6.
glazes were coated with a Au/Pd alloy to ensure high conductivity. For scanning electron microscopy (SEM)/EDX analysis, an acceleration voltage of 20 kV was used at working distances of 9.5 and 10 mm. The colors values (L*, a, and b) of the specimens were determined using an “X-rite” color identifier. The surface roughness values of the specimens were measured using a roughness analyzer (KR 100, Ceramic Instruments), while their brightness values were determined using a glass meter (Multi Gloss 268 Plus, Konica Minolta). To observe the sintering behaviors of the frits, a heat microscope (ODHT-HSM 1600/ 50, Misura 3.32) was used. The sintering, softening, sphere, half-sphere, and melting temperatures of the frits were determined by heating the frit samples to 400 °C at a rate of 30 °C/min and to 1400 °C at a rate of 10 °C/min. To determine the crystallization temperatures of the frits, differential thermal analysis (DTA) (Netzsch STA 409 PC) was performed; during the analyses, the frits were heated to 1200 °C at a rate of 10 °C/min. The ISO 10545 standard defines the tests used on traditional ceramic tiles and glazes. According to this standard, chemical resistance, thermal shock resistance, staining resistance, Mohs (surface) hardness, surface abrasion resistance, and crazing resistance tests were
bright opaque glaze, specifically bright and matt opaque frits. The main reason for using the matt opaque frits is to overcome the boiling problem that is associated with their high softening temperatures. Wastecontaining MOF1-A3 and MOF1-A5 frits were employed as matt opaque frits, given their similar surface properties to a standard MOF1 frit. The standard bright opaque glaze was labeled “BOG” and those glazes incorporating MOF1-A3 and MOF1-A5 were additionally labeled using the code for the boron waste (e.g., BOG-A3). The glaze application was performed in the same way as described in Fig. 2 but with a slight difference in firing process, which was carried out at a peak temperature of 1215 °C for 43 min. To determine the chemical compositions of the frits, X-ray fluorescence (XRF) measurements and energy-dispersive X-ray spectroscopy (EDX) were performed. The voltage and current values for Ca and K were 40 kV and 75 mA, respectively, while those for Cl, S, P, Si, Al, Mg, Na, F, and B were 30 kV and 100 mA. To determine the mineralogical structures of the glazes, X-ray diffraction (XRD) analyses (Rigaku RINT 2000) were performed using an acceleration voltage of 40 kV and a current of 30 mA. The specimens were inspected for 2θ values of 10–70° at a scanning rate of 2°/min. Prior to the microstructural analysis, the
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Fig. 10. SEM images of cross-sections of (a) MOF1, (b) MOF1-A1, (c) MOF1-A2, (d) MOF1-A3, and (e) MOF1-A4.
present in the waste-containing frits, similar to a standard MOF1 glaze. The width of the peak of the amorphous phase was higher for the wastecontaining frits than for MOF1, given that the elements present in the waste tend to form compounds with an amorphous structure (CaO and B2O3). In the pattern for the standard MOF1 glaze, the intensity of the peak related to the diopside crystals is higher than that of the peak
conducted on the obtained BOG-A3 and BOG-A5 bright opaque glazes. 4. Results and discussion The XRD patterns shown in Fig. 3 and Fig. 4 indicate that small amounts of diopside (MgCaSi2O6) and zircon (ZrSiO4) crystals were
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Fig. 11. SEM images of cross-sections of (a) MOF1, (b) MOF1-A5, and (c) MOF1-A6.
Figs. 10 and 11 show cross-sectional SEM images of the glazes including waste as well as that of MOF1, while Figs. 12 and 13 shows higher-magnification images of the areas marked by the yellow lines in Figs. 10 and 11. The pores in the standard glaze are interconnected, while those in the newly developed glazes are not, and the latter are smaller than the pores in the standard glaze. As shown in Figs. 14 and 15, the size, shape, and distribution of the crystals in all the bright opaque glazes are very similar, independent of the imaged area. EDX analysis of the crystals also proved the presence of zircon crystals in the structures. The sintering curves (Figs. 16 and 17) of the frits developed using the waste show that their softening and melting temperatures are lower than those of a standard frit (Table 3). The critical temperatures of the MOF1-A4 frit, which produced the brightest glaze, are the lowest. This observed decrease in sintering temperature can be explained based on the fluxing effects of both CaO and B2O3. Together, they create a more effective flux than the standard composition, resulting in a decrease of the sintering temperature. Further, as shown in the DTA curves in Figs. 18 and 19, the crystallization temperatures of the frits are similar (around 950 °C). However, the crystallization peak of the standard MOF1 frit is sharper and of a higher intensity than those of the waste-containing frits. The CaO and
attributable to the zircon crystals. However, in the pattern for MOF1A5, the intensities of the two peaks are similar. Furthermore, the degree of crystallization of the waste-containing frits was lower owing to the presence of the glass-forming fluxes, as evidenced by the low intensity of the crystallization peaks. XRD analysis of the surfaces of BOG-A3 and BOG-A5 (Fig. 5) showed that they only contained zircon crystals in addition to the amorphous phase, in the same manner as BOG. Mineralogical analysis proved that the addition of boron waste to the frit composition has no undesired effect on the type of crystals formed on the surface. Figs. 6 and 7 show SEM images of the surfaces of waste-containing glazes as well as that of the MOF1 glaze, while Figs. 8 and 9 shows higher-magnification images of the areas marked with the dotted lines in Figs. 6 and 7. The produced glazes do not have highly porous surfaces such as that of the standard MOF1 glaze. The shape and density of the pores can be attributed to the effect of the viscous sintering process. At temperatures higher than the glass-transition temperature (approximately 1100 °C) [17], the viscosity of the frits decreases. Furthermore, at higher temperatures, the large amount of Ca present in the structure starts to act as a flux along with B2O3. Owing to these fluxes, the extent of sintering and densification increases, leading to smaller pores [18–20].
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Fig. 12. SEM images of cross-sections of (a) MOF1, (b) MOF1-A1, (c) MOF1-A2, (d) MOF1-A3, and (e) MOF1-A4.
differences are caused by the different amounts of metal oxides present in the waste compositions, especially fluxing oxides. As determined from the DTA curves (Fig. 21), the sintering mechanism stopped between 950 and 980 °C due to the exothermic peak corresponding to the formation of zircon crystals in the structures. The formation of zircon crystals increased the viscosity of the glaze and blocked the bulk flow,
B2O3 present in the waste-derived frits cause viscous sintering, which leads to the formation of an amorphous structure. As a result, the crystallization peaks of the newly developed frits are wider and lower in intensity [18–20]. The sintering curves (Fig. 20) of BOG-A3 and BOG-A5 show that their critical temperatures are close to that of BOG. The slight
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Fig. 13. SEM images of cross-sections of (a) MOF1, (b) MOF1-A5, and (c) MOF1-A6.
containing bright opaque glazes are very similar to the standard BOG. BOG-A3 exhibits a greater brightness than BOG-A5. The results of the applied ISO 10545 tests are listed in Table 6. The waste-containing bright opaque glazes exhibit very similar characteristics to those of a standard glaze. Regarding the decorative use of the glazes and areas in which they are likely to be applied, staining resistance and chemical resistance are important both visually and technically. The test results showed that the waste-containing glazes are well suited to such applications.
which a caused a break in the sintering. Once the system reached 1070 °C (the softening point), the glaze became viscous again and the sintering continued. The endothermic peak around 1200 °C can be explained as an indication of the melting of zircon crystals in the amorphous (glassy) phase. Images of the final glaze layers formed by firing are shown in Fig. 22. An image of the standard MOF1 glaze is also shown for comparison. The results of the color, surface roughness, and brightness analyses are listed in Table 4. The brightness and roughness values for MOF1-A3 and MOF1-A5 are very similar to those of the standard glaze, while the others are brighter and smoother than the standard glaze. The seven glazes could be arranged in order of brightness and roughness as follows: MOF1-A4 > MOF1-A2 > MOF1-A1 > MOF1-A6 > MOF1A3 > MOF1-A5 > MOF1 and MOF1-A5 > MOF1 > MOF1-A6 > MOF1-A1 > MOF1-A2 > MOF1-A4. This also shows that there is an inverse relationship between a surface's roughness and its brightness. Table 5 compares color and brightness values of BOG-A3 and BOG-A5 with those of BOG. As expected, the visual properties of the waste-
5. Conclusions In the present study, colemanite mining and enrichment waste from the Bigadiç and Bandırma plants was successfully used as an alternative source of B2O3, in place of boric acid used in the industrial production of opaque matt frits and bright opaque glazes in the ceramics industry. The obtained final product could be applied to conventional tile production even at lower sintering temperatures. A low CaO content in transparent frits allowed for the limited addition of waste. This method
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Fig. 14. (a), (d), (g) SEM (backscattered electron) images of surfaces of BOG, BOG-A3, and BOG-A5. (b), (e), (h) SEM (backscattered electron) images of marked areas in (a), (d), and (g) at higher magnification(c), (f), (ı) EDX analysis of dotted crystals in (b), (e), and (h).
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Fig. 15. (a), (d), (g) SEM (backscattered electron) images of cross-sections of BOG, BOG-A3 and BOG-A5. (b), (e), (h) SEM (backscattered electron) images of the marked areas in (a), (d) and (g) in higher magnification (c), (f), (ı) EDX analysis of dotted crystals in (b), (e) and (h).
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Fig. 16. Results of thermal analysis of frits using heat microscope.
Fig. 17. Results of thermal analysis of frits using heat microscope.
Table 3 Results of thermal analysis of developed frits. FRIT
Sintering temperature °C
Softening temperature °C
Melting temperature °C
MOF1 MOF1-A1 MOF1-A2 MOF1-A3 MOF1-A4 MOF1-A5 MOF1-A6
838 822 820 828 802 818 812
1200 1170 1172 1188 1134 1204 1194
1252 1218 1212 1224 1194 1236 1224
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Fig. 18. Results of DTA analysis of frits.
Fig. 19. Results of DTA analysis of frits.
Fig. 20. Results of thermal analysis of bright opaque glazes using heat microscope.
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Fig. 21. Results of DTA analysis of bright opaque frits.
Acknowledgements
also reduced the sintering temperature but prevented the waste from being used as a complete substitute for boric acid [14]. The resulting bright opaque glaze compositions successfully passed EN ISO 10545 test requirements, providing adequate levels of surface abrasion, chemical resistance, thermal shock resistance, and staining characteristics. The present study indicates that the waste held near enrichment plants for further treatment can be employed as a valuable raw material for ceramics, and can contribute to sustainable production in the ceramics industry.
This study was funded jointly by the Eczacibasi Group (A15w06) and the National Boron Institute Turkey (BOREN) (2015-31-07-15002), with the aim of identifying a method of utilizing boron waste for ceramics production in a sustainable manner.
Fig. 22. Digital photographs of MOF1, MOF1-A5, and MOF1-A6 glazes, applied to tile surfaces.
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Table 4 Color, brightness, and roughness of developed glazes. Glaze
MOF1 MOF1-A1 MOF1-A2 MOF1-A3 MOF1-A4 MOF1-A5 MOF1-A6
Color
Brightness
Roughness
L*
a*
b*
20°
60°
80°
µm
92.47 89 89.28 89.3 88.31 90.94 90.45
− 0.1 0.4 0.6 0.72 0.6 0.22 0.32
0.76 1.45 2.24 2.5 2.27 1.4 1.64
1.1 2.4 4.1 1.3 6.9 1.1 1.4
2.4 16.2 23.8 5.2 33.2 2.7 6.2
2.4 38.9 55.8 6.9 64.1 2.9 7.2
18.72 4.97 4.02 12.19 2.21 19.35 10.13
Table 5 Color and brightness values of bright opaque glazes. Glaze
BOG BOG-A3 BOG-A5
Color
Brightness
L*
a*
b*
20°
60°
80°
92.05 91.72 91.53
− 0.78 − 0.76 − 0.76
2.28 2.77 2.91
75 72.5 75
93.4 91.1 90.9
94.3 96.2 93.5
BOG
BOG-A3
BOG-A5
3 (1500 rpm)
3 (1500 rpm)
3 (1500 rpm)
1 day
GA
GA
GA
1 day
GLA
GLA
GLA
4 days 4 days 1 day
GLA GLC GLA
GLA GLC GLA
GLA GLC GLA
4 days 4 days 4 days
GHA GHC GHA
GHA GHC GHA
GHA GHC GHA
GA Suitable
GA Suitable
GA Suitable
5 5 5 5 5 5 5 5 4 Suitable
5 5 5 5 5 5 5 5 4 Suitable
5 5 5 5 5 5 5 5 4 Suitable
Table 6 ISO 10545 test results for BOG, BOG-A3, and BOG-A5. Test Surface Abrasion Value (PEI) (TS EN ISO 10545–7) Chemical Resistance (ISO 10545–13)
Description
House Chemicals Swimming Pool Salts Low-Concentration Acids and Alkalis High-Concentration Acids and Alkalis
Cement Joint Cleaner Thermal Shock Resistance (ISO 10545–9) Staining Tests (ISO 10545–14)
Amonium Chloride (100 g/l) Sodium Hypochloride (20 mg/l) HCl (%3) KOH (30 g/l) Citric Acid (100 g/l) HCl (%18) KOH (100gr/l) Lactic Acid − 5%
Iron Oxide Olive Oil Alcohol Iodide Methylene Blue Potassium Permanganate Black Joint Filler Pencil Test Shoe Mark
Mohs (Surface Hardness) Crazing Resistance
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