Supersaturation and temperature dependency of gibbsite growth in laminar and turbulent flows

An agglomeration efficiency model for gibbsite precipitation in a turbulently stirred vessel

“…(36) is primarily carried in the G term, the effect on and is weak. The strong positive correlation between G for gibbsite and supersaturation is well documented (Li et al, 2003). The strong increase in observed experimentally as supersaturation is increased is consistent with Eq.…”

Organic compounds in the processing of lateritic bauxites to alumina Part 2: Effects of organics in the Bayer process

“…a TOS/TOC ratio of 2 (Rosenberg and Healy, 1996)) the loss of theoretical yield caused by 20 g/L TOC is about 9 g/L Al 2 O 3 , or 7%. It has been noted that about 90 million tonnes of aluminium hydroxide is produced by precipitation from Bayer process liquors annually (Li et al, 2003), which is probably the greatest rate of production of all precipitates in hydrometallurgy. It is a slow chemical reaction, requiring high seed densities (250 to 1000 g/L), long holding times (24 to 36 h) and low temperatures (the liquor is cooled from about 80°C to about 60°C during precipitation) to maximise the yield of product (Newchurch and Moretto, 1990;Pearson, 1955).…”

Kaolinite dissolution and precipitation kinetics at 22°C and pH 4

“…The main differences between these models are in their assumptions about the rate of surface nucleation and the rate of lateral spreading of the nuclei across the crystal surface. The two-dimensional nucleation growth models can be expressed as (Li et al, 2003) R ¼ k sn F ðX À 1Þ exp À / 2 ðkT Þ 2 1 lnðXÞ…”

“…Such two-dimensional nucleation growth models have been discussed extensively in the case of gibbsite crystal growth that occurs in the industrial Bayer process (Veesler and Boistelle, 1994;Farhadi and Babaheidary, 2002;Li et al, 2003). Gibbsite has an analogous structure to that of the micas and the neutral aluminum hydroxide sheets are typically found to be sandwiched between silicate sheets in important clay groups, such as the kaolinite, illite, and montmorillonite/smectite.…”