Effects of monohydroxy-alcohol additives on the seeded agglomeration of sodium aluminate liquors

A series of monohydroxy-alcohol additives were adopted in Bayer process. The effects of dosage and carbon chain length on precipitation ratio of sodium aluminate liquors and particle size distribution (PSD) of gibbsite were investigated. Experimental results indicated that: all three monohydroxy-alcohols can increase precipitation ratio of sodium aluminate liquors at the proper dosage. They can accelerate precipitation process obviously at lower dosage at the beginning and yet last longer effects at higher dosage. Particle size of gibbsite products is enlarged when I-Octadecanol is added at low dosage, yet the product fines under all other conditions. It can be concluded that: long chain additives with low dosage or short chain additives with high dosage is favorable for the seeded agglomeration of sodium aluminate liquors. The relationship between carbon chain length and its dosage may be complementary. Action mechanism among monohydroxy-alcohol additives, sodium aluminate liquors and gibbsite crystals will be further investigated based on the information mentioned above.