Sizing an Organic Control System for the Bayer Process

Recovery of Fine Aluminum Hydroxide with High Whiteness Index from Low Quality Bauxite Using Caustic Roasting and Water Leaching

“…The advantage of this roast-leach process is that pure and colorless sodium aluminate liquors can be produced without any organic co-dissolved during leaching, as occurs in the Bayer process. A typical Bayer plant liquor will contain a total organic carbon (TOC) of 10-20 g carbon/L [22,23]. Figure 7 shows the measurements of TOC (total organic carbon) to be in the range 0.1-0.3 g/L TOC as carbon (within the error limit for the technique) over a wide range of roasting temperature.…”

“…Roasting bauxite before its digestion can also potentially destroy most organic matter, which exist in the ore up to 0.5% w/w carbon [21]. Due to the cyclic nature of the Bayer process, most organic matter dissolves during pressure digestion, forming humate, oxalate, formate and other carboxylates, etc., which accumulate and can reach 20 g carbon/L or higher after several years of operation unless removed [21][22][23]. Apart from affecting the ATH yield during precipitation, the presence of organics, especially humates, darkens the Bayer liquor into a red-brown color, preventing the production of high quality specialty ATH or alumina with high whiteness [2,10,24].…”

Feasibility of Applying Alkaline-Earth Metal Carboaluminates for Bayer Process Aluminate Solution Purification from Organic Impurities

“…The most promising are purification methods of aluminate solutions from organic sub-stances that allow controlling the content of harmful classes. Sorption methods fully comply with the purification selectivity condition [8,9,10,11]. They are also advantageous because of the fact that they can be implemented in conditions fully complying with the hardware and technology parameters of alumina production.…”