Assessment of soda ash calcination treatment of Turkish trona ore

¹ Republic of Turkey Ministry of Energy and Natural Resources, Nuclear Energy Project Implementation Department, Ankara, Turkey
² Middle East Technical University, Mining Engineering Department, Ankara, Turkey

^a Corresponding author: sgezer@enerji.gov.tr

Abstract

Trona is relatively rare, non-metallic mineral, Na₂CO₃ · NaHCO₃ · 2H₂O. The pure material contains 70.3% sodium carbonate and by calcination the excess CO₂ and water can be driven off, yielding natural soda ash. The terms soda ash and sodium carbonate are used interchangeably. Trona calcining is a key process step in production of soda ash (sodium carbonate anhydrate) from the relatively cheap trona ore. The calcination reaction may proceeds in a sequence of steps. Depending on the conditions, it may result in formation of either sodium carbonate monohydrate (Na₂CO₃ · H₂O), sodium sesquicarbonate or weigschederite (Na₂CO₃ · 3NaHCO₃). The Beypazarı Turkish trona deposit is the second largest deposit in the world with the content of 84% trona. The decomposition of trona appeared to be a single stage process across the temperature range studied (150-200 °C) with the representative samples of different size fractions in the draught up metallurgical furnace. The optimum particle size and calcination time were −6.35 mm and 30 minutes, respectively, at calcination temperature of 175 °C in a metallurgical furnace. Microwave-induced dry calcination of trona was possible and 5 minutes of calcination time at a power level of 900 was sufficient for complete calcination of −6.35 mm feed. This includes short time calcinations with the goal of improving economics and simplifying the thermal process.