Investigation of TiO2-added refractory brick properties from calcined magnesite raw material

Abstract

This paper is the second part of a study on recycling magnesite and chromite ore (in the 0 -10 -3 m fraction) powder, which remains as a production process waste. In this work, 90% magnesite-10% chromite composition was used as a brick composition. Compaction pressure, sintering temperature, ratio of TiO 2 addition, and influence of bonding type on refractory properties were examined. In refractory brick production, one of the most important parameters that affects the properties of the product is the particle size distribution of the blend. Experiments show that using a magnesite particle size of -10 -3 m and a chromite particle size of -63´10 -6 m affects the properties of the product in a positive way. Experiment blends with the particle sizes selected above were used. Magnesite ore was used in experiments after calcination at 1200°C for four hours. In the experiments we mention, MgCl 2 and MgSO 4 solutions were used as a bonding agent, as a result of which a 6% bonding ratio of MgCl 2 and MgSO 4 solutions was determined as optimum. The effect of compacting pressure on the refractory properties was studied, and the optimum compacting pressure was determined as 180 MPa. For bricks prepared using calcined magnesite, the optimum sintering temperature was found to be 1750°C. The positive effect of TiO 2 addition on the magnesite chrome refractory brick structure has been reported in the literature. Thus, 1, 3, 5, and 7 wt.% TiO 2 ratios were used in the blend, and the refractory properties were positively affected by the 3% TiO 2 addition. Taking the result of the MgCl 2 and MgSO 4 bonding solution into consideration, it is clear that the refractory properties of brick can be improved by using a mixture of MgCl 2 and MgSO 4 bonding solutions. In light of the above concept, bonding mixtures with 1:3, 1:5, and 1:10 ratios were prepared, and these bonding mixtures were studies as a bonding material. The experimental results show that the cold crushing strength (CCS) and volume density of bricks increase, whereas the porosity decreases when a 1:5 ratio of MgCl 2 and MgSO 4 in the bonding mixture and 3% TiO 2 addition were used. Microstructural study of the produced bricks was done using scanning electron microscope (SEM). In addition to this, the phases forming the structure of brick were examined via x-ray diagrams of the material. In bricks where a mixture of a 1:5 MgCl 2 : MgSO 4 bonding solution was used as bonding agent and 3% TiO 2 was added, spinel (magnochromite (MgCr 2 O 4 )), magnesium orthotitanate (Mg 2 TiO 4 ), monticellite (CaMgSiO 4 ), and forsterite (Mg 2 SiO 4 ) phases were found. The perovskite phase was not observed during the experimental study.

Review on the elaboration and characterization of ceramics refractories based on magnesite and dolomite

“…The results indicated a prospect for using the waste as a co-flux in wall tile formulations. Kalpakli [60] Investigation of TiO2-added refractory brick properties from calcined magnesite raw material 90% magnesite-10% chromite composition was used as a brick composition. Compaction pressure, sintering temperature, ratio of TiO2 addition, and influence of bonding type on refractory properties were examined.…”

Effect of titanium oxide addition on magnesia refractories

“…According to the authors, the optimum concentration of titania in spinel is 4 wt%. An addition of titania also exerts a favourable impact on the structure of magnesia chrome refractory bricks [23] and silica refractories [24]. In the latter case, an addition of 0.5 wt% titania results in the formation of the highest amount of tridymite phase in the final product.…”

Sintering and Performance of MgO from Bischofite with ZrO₂ Additive

“…An exsolution precipitate of ZrO 2 is observed indicating that Zr interacts with the parent MgO as a solid solution and precipitates as a higher temperature in the liquid secondary phase. Kalpakli [6], Lucion et al [7] investigated the effect of TiO 2 on the properties of magnesite chrome refractory brick, MgO and MgO-CaO mixtures, respectively. Petric et al [8,9] studied activated sintering of magnesium oxide from seawater with 1, 2 and 5 wt% TiO 2 .…”