How to use real-time guidance in alumina production for raw material blending and ore allocation
Release time:
2026-01-07
Challenge:
In alumina production via the Bayer process, the objective of “raw material blending” is not to achieve the highest grade but rather to operate the digestion, precipitation, and calcination systems within their optimal operating windows, while minimizing overall costs.
It’s not that the higher the Al₂O₃ content, the better; rather:
A/S stability + soluble alumina stability + minimal process risk + lowest total cost per ton of alumina
Therefore, the core process indicator for ore blending guidance—A/S (Al₂O₃ / Reactive SiO₂)—is the top priority.
Regarding the impact on the process, a low A/S ratio leads to a sharp increase in caustic soda consumption and a large volume of red mud.
A/S fluctuates, the leaching system is unstable, and process parameters drift; when A/S is too high and ore prices are elevated, economic viability may not be assured.
Therefore, the primary principle of ore blending is to maintain a stable A/S ratio, rather than striving for the highest possible A/S.
Secondly, there is available aluminum oxide (Avail. Al₂O₃), which determines how much alumina can be produced per unit of ore.
Reactive silica (Reactive SiO₂) is the type of silica that truly “consumes alkali”; it determines the alkali consumption, the amount of red mud, and the washing load.
When blending ores, the target is “reactive silicon,” not total SiO₂.
Iron, titanium, and LOI (which affect “hidden costs”)—these components actually influence the Fe₂O₃ content in red mud and its settling performance, as well as the risk of TiO₂ leaching and scale formation.
Solution:
In alumina production, online measurement of ore grade is essential for monitoring the aforementioned parameters. During pulp preparation, it is necessary to adjust the caustic soda concentration and the liquid-to-solid ratio; therefore, real-time measurement of feed solids content becomes critically important. Plasen’s non‑nuclear solids‑content technology provides valuable guidance, while the resulting data can be fed into the online RP measurement system at the end of the digestion stage to generate feedback and optimize ore blending. By leveraging online analytical instruments for trend analysis and early warning—such as detecting a declining A/S ratio—operators can proactively switch to higher‑A/S ore, thereby preventing sudden spikes in caustic consumption.
Slow transition during mine-source switching to prevent process shocks.
Solution
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