In this research, the use of borax sludge, which is generated in borax industry, as an additive in wall tile, was investigated. The wall tile samples were prepared by adding boron waste to the wall tile composition in the range of 2% - 10%. The effect of boron waste on the physical and mechanical properties of wall tile was determined. The results obtained were compared with the control tile and Turkish Standards (TS). The boron waste addition up to 8 wt.% was found to improve the water absorption and strength of wall tile.
Turkey has 72% of the total world boron reserves and is one of the world’s largest producers of borates with 2.2 million ton/year. Most boron reserves are in the form of colemanite (2CaO∙3B2O3∙5H2O) and tincal (Na2O∙2B2O3∙10H2O) in Turkey. Borates are used in over 100 industries including glass, ceramics, enamels, detergents and insulation fibers [
The concept of utilization of solid wastes and sludges contains the main principles of recovery, recycling and converting to value added products. Recovery and recycling is a well-known process. But, it again produces waste which causes disposal problems [
The borax sludge used in this study was provided from Etibank Kırka Borax Plant in Eskişehir, Turkey. The solid and liquid parts of this sludge were separated by filtering. The solid part was dried at room temperature and then sieved by using ASTM standard sieves. The particles smaller than 100 mesh were used in the experiments. The chemical analysis of boron waste was carried out by using XRF ARL 8680. The chemical analysis for boron oxide content was achieved by volumetric method [
Before the wall tile samples were prepared, the moisture contents of boron waste and the wall tile mixture were determined. According to this, the weight of wall tile mixture was adjusted to 2500 g and boron waste ratios in the wall tile samples were 0%, 2%, 4%,
Component (%, w/w) | Boron waste | Wall tile mixture |
---|---|---|
SiO2 | 9.82 | 57.78 |
Al2O3 | 1.30 | 19.15 |
Fe2O3 | 1.49 | 1.53 |
TiO2 | - | 0.33 |
CaO | 16.85 | 3.81 |
MgO | 13.01 | 3.12 |
Na2O | 10.30 | 1.12 |
K2O | 1.01 | 2.12 |
B2O3 | 19.44 | - |
SO3 | - | 0.08 |
Loss of ignition | 26.78 | 10.96 |
6%, 8% and 10%, by weight. The wall tile sample without boron waste was designed as control tile. After 0.9% Na2SiO2 and 50% water were added to these samples, they were ground and mixed in a ball ceramic mill of 5 L capacity in the range of 50 - 60 rpm for 15 min. These mud samples were passed through a 150 μm sieve and then were completely dried in an oven at 105˚C ± 5˚C. The dried samples were ground in an agate mortar. The obtained powder was humidified at 6% humidity ratio and then was molded in 100 mm × 80 mm × 6 mm molds by pressing at 15 N/mm2. The samples prepared in this way were dried in an oven at 80˚C for 12 h and then were fired in a roller furnace at 1130˚C for 35 min. The tests of drying shrinkage, firing shrinkage, weight loss, bulk density, water absorption, drying strength and firing strength were applied to samples according to TS EN ISO 10,545 [
The chemical analysis and XRD of the boron waste are given in
Five types of wall tile samples were prepared with boron waste at various ratios, and one control tile without boron waste. The drying shrinkage, firing shrinkage, weight loss, bulk density, water absorption, drying strength and firing strength values of these samples were determined. The results obtained are given in
Boron waste ratio (%, w/w) | Drying shrinkage (%) | Firing shrinkage (%) | Weight loss (%) | Bulk density (g/cm3) | Water absorption (%) | Drying strength (N/mm2) | Firing strength (N/mm2) |
---|---|---|---|---|---|---|---|
0 | 0.29 | 1.10 | 10.14 | 1.82 | 17.40 | 2.89 | 13.69 |
2 | 0.50 | 1.14 | 10.54 | 1.81 | 17.34 | 3.17 | 13.86 |
4 | 0.66 | 1.20 | 10.87 | 1.83 | 14.97 | 3.24 | 13.87 |
6 | 0.87 | 1.82 | 11.19 | 1.84 | 14.56 | 3.42 | 15.16 |
8 | 0.31 | 1.93 | 11.45 | 1.88 | 13.82 | 3.67 | 16.43 |
10 | 0.59 | 2.12 | 11.64 | 1.77 | 16.15 | 3.72 | 15.87 |
TS 202 | - | - | - | min. 1.70 | max. 20.00 | - | min. 15.00 |
As seen in
0.29% and 1.10%, respectively, those of the wall tile with 10% boron waste addition are 0.59% and 2.12%, respectively. The increase in drying shrinkage is due to the clay amount of tile body which increases with the clay content of boron waste used in the production of tile. The release of mechanical water and hydroscopic water from the clay and kaolin during drying causes that particles in the body come closer and closer together until they touch, leading to shrinkage [
The wall tile including boron waste has a bigger loss of weight by firing and a bigger firing shrinkage depending on how much more boron waste is contained in the tile (
The drying strength results are shown in
As seen in
Borax sludge was tested to determine whether this material can be used as an additive in wall tile production or not. The following results were obtained:
1) The use of boron waste in the control wall tile composition increases the drying shrinkage and the firing shrinkage.
2) The wall tile including boron waste has a bigger loss of weight by firing.
3) The water absorption of tile decreases as the boron waste content of the wall tile is increased.
4) The drying strength and firing strength of the tiles containing boron waste are higher than those of the control tile.
5) The addition of boron waste up to 8% improved the wall tile quality with respect to water absorption, drying strength and firing strength without compromising the other properties.
6) Boron waste coming from the borax industry may be used as an additive for wall tile production to the extent of a maximum 8 wt.%. By this way, economic loss and the soil and underground water pollution sourced from the borax sludge can be prevented. The production cost of tile can be reduced due to the saving material by the use of boron waste. In addition, energy saving is provided since the boron waste in powder form requires less grinding.
We thank Eskişehir Osmangazi University Research Foundation (Project No. 2000/6) for financial support, Etibank Kırka Borax Plant for borax sludge and Altın Ceramics Plant for laboratory facility.
Özdemir, M. and Kıpçak, İ. (2016) Use of Borax Sludge as an Additive in Wall Tile. Journal of Materials Science and Chemical Engineering, 4, 39-45. http://dx.doi.org/10.4236/msce.2016.412005