Improvement of treated spent pot lining reactivity in cementitious material by calcination

Abstract

Treating spent pot lining by the Low Caustic Leaching and Liming (LCLL) process creates an inert non-hazardous residue called LCLL Ash. Ground as a fine powder and calcined, LCLL Ash showed a pozzolanic behavior in cement. The effect of the calcination temperatures on LCLL Ash reactivity was studied by compressive strength activity index, Frattini tests, and RILEM R3 tests, followed by XRD analysis. When calcinating LCLL Ash at temperatures below 800 °C, no differences in reactivity were seen between calcined and non-calcined LCLL Ash. At 800 °C, the formation of nepheline caused an alkalis uptake, showing a slightly lower reactivity of LCLL Ash than cement at 112 days. Beyond 800 °C up to 1200 °C, calcined LCLL Ash manifested better amorphization of phases and increased reactivity, similar to cement at 112 days. Finally, neither delay on hydration nor hydroreactivity was observed with calcined LCLL Ash starting at 800 °C.

Keywords

• Low caustic leaching liming
• Treated spent pot lining
• Blended cement
• Hazardous waste
• Aluminum
• Supplementary cementitious materials