Citric Acid → Tricalcium Citrate

Participants

Reaction Conditions

Reaction Steps

A calcium citrate sample was prepared by reacting 2763.8 lbs. of citric acid with 1600 lbs. calcium hydroxide (97-98% Ca(OH)2 by analysis) in the presence of 1433 gallons of water. The mole ratio of calcium hydroxide to citric acid was very slightly less than 3:2, actually 2.92:2. The citric acid (Pfizer fine granular, food grade) was mixed in a large batch tank with 675 gallons of cold water. The calcium hydroxide (Mississippi lime, hydrated lime, food code) was mixed in a separate batch tank with 75 gallons of cold water. The calcium hydroxide slurry is then pumped into the citric acid solution at a rate to deliver the entire slurry in 10-15 minutes. It is necessary to have good agitation during the entire reaction and mixing process. The remaining 83 gallons of water is used to rinse the calcium hydroxide tank and transport lines. Due to the heat of reaction, the temperature of the resultant slurry was increased from an initial value of 15° C. (60° F.) to a maximum of 57° C. (134° F.). After the reaction is complete, the batch is cooled to 80°-90° F. The final pH of this concentrated slurry (22% calcium citrate, dry basis) should fall within the range 3.8-4.6 or can be adjusted up or down using the reacting ingredients. The slurry is then dried via spray drying utilizing a rotary wheel (7600 rpm). The outlet temperature was adjusted to 225° F. and the inlet temperature was 450° F.

Provenance & Evidence