Wet calcining of trona (sodium sesquicarbonate) and bicarbonate in a mixed solvent

摘要

Trona ore is used in large amounts for the production of soda ash. A key step in this process is the conversion of trona (sodium sesquicarbonate: Na_2CO_3·NaHCO_3·2H_2O) into soda (sodium carbonate anhydrate: Na_2CO_3). Currently, this conversion is done industrially by calcining of the raw ore in rotary calciners at ca. 120 deg C or higher (Natural Soda Ash--Occurrences, Processing, and Use, Van Nostrand Reinhold, New York, 1991, p. 267). Trona can however be converted at lower temperatures by using a "wet calcining" technique. In this technique, trona is contacted with an organic or mixed organic-aqueous solvent at a conversion temperature that depends on the water activity of the used solvent.