Cost-Effective and Sustainable Preparation of Porous Mullite-Based Ceramics Combining MoO₃ Recovery from Industrial Calcine

Abstract

The preparation of porous mullite-based ceramics (PMCs) suffers from the pollution of fluorinated catalysts and high cost and large consumption of additives. The volatilization method for MoO3 recovery from industrial Mo calcine has demerits of low recovery efficiency and high requirements for equipment and waste treatments. Herein, this work presents a new strategy to co-produce pure MoO3 and PMCs by single-step roasting of green bodies composed of industrial Mo calcine, kaolin clay, and alumina. Ribbon-like MoO3 is recovered with a high recovery efficiency of 95.71%, while simultaneously acting as the pore-forming agent and crystallization catalyst to construct PMCs. The properties of PMCs, such as linear shrinkage, open porosity, bulk density, compressive strength, and thermal conductivity, are reported. The PMC sintered at a low temperature of 1100 °C with the addition of 200 wt % industrial Mo calcine shows great potential to serve as a thermal insulating material. The recovery of MoO3 is better than the traditional method because the PMC can absorb the melted calcine, intensify MoO3 volatilization, and incorporate the volatilizing slag. Generally, this work provides a cost-effective and sustainable method to co-produce pure MoO3 and PMCs with mutual promotion and zero waste.

Near‐net‐size preparation of porous mullite matrix ceramics with in situ formed 3D mullite whisker network

“…Under the liquid phase environment, SiO 2 was produced from the decomposition of kyanite, and α-Al 2 O 3 was gradually dissolved, consequently they reacted with each other and formed the aluminosilicate glassy phase with low melting point. 12,13 Therefore, a small amount of Mo could be detected in the glassy phase at 800 • C. The viscosity of the glassy phase was effectively decreased by the presence of Mo 18 ; therefore the migration rate of atoms could be accelerated in the glassy phase, and the precipitation of mullite could also be promoted from the glassy phase.…”

“…9,10 Ma et al 11 reported that kaolin, α-Al 2 O 3 , boehmite sol, MoO 3 , and AlF 3 were used as raw materials to prepare porous whisker-structured mullite ceramics with low sintering shrinkage by reaction sintering, which have porosity of 73% and compressive strength of 15 MPa. Similarly, Li et al 12 fabricated porous mullite-based ceramics with sintering shrinkage of 3.5%, porosity of 79%, compressive strength of 12 MPa from kaolin, Al 2 O 3 , and industrial Mo calcine by reaction sintering. Xu et al 13 reported that porous mullite ceramics with sintering shrinkage of 1.86%, porosity of 61.91%, and flexural strength of 9.35 MPa were prepared by the solid reaction between mullite precursor powders and MoO 3 .…”

“…reported that kaolin, α‐Al 2 O 3 , boehmite sol, MoO 3 , and AlF 3 were used as raw materials to prepare porous whisker‐structured mullite ceramics with low sintering shrinkage by reaction sintering, which have porosity of 73% and compressive strength of 15 MPa. Similarly, Li et al 12 . fabricated porous mullite‐based ceramics with sintering shrinkage of 3.5%, porosity of 79%, compressive strength of 12 MPa from kaolin, Al 2 O 3 , and industrial Mo calcine by reaction sintering.…”

Use of Coal Gangue to Prepare Refractory Saggars with Superior Corrosion Resistance and Thermomechanical Properties for the Calcination of Li-Ion Battery Cathode Materials

“…7,8 Because mullite and/or andalusite grains could also be involved in the in situ formation of KAS 4 , ceramic bonding can be generated between mullite and/or andalusite and KAS 4 , resulting in improved thermal and mechanical properties. 7,8 However, the mullite and andalusite employed in industry are either synthesized via sintering and/or electronic fusion at elevated temperatures using industrial/laboratorygrade reagents 9,10 or mined beforehand. A high operating energy is thus needed, resulting in high CO 2 emission levels.…”

“…Based on the corrosion mechanism of refractory materials in contact with LNCM materials, KAlSi 2 O 6 (KAS 4 ), which shows excellent corrosion resistance against LNCM materials, is commonly introduced in mullite-based and andalusite-based refractories. , KAS 4 is formed in situ and tightly wrapped around mullite and andalusite grains, thereby physically avoiding the direct contact of mullite/andalusite grains with LNCM precursors/materials. , As a consequence, the obtained mullite–KAS 4 -based and andalusite–KAS 4 -based materials exhibit superior corrosion resistance against LNCM materials. , Because mullite and/or andalusite grains could also be involved in the in situ formation of KAS 4 , ceramic bonding can be generated between mullite and/or andalusite and KAS 4 , resulting in improved thermal and mechanical properties. , However, the mullite and andalusite employed in industry are either synthesized via sintering and/or electronic fusion at elevated temperatures using industrial/laboratory-grade reagents , or mined beforehand. A high operating energy is thus needed, resulting in high CO 2 emission levels.…”