Sustainable scale control technology in alumina production
Using scale inhibitors in alumina production is necessary to prevent the accumulation of large amounts of scale in manufacturing equipment. This buildup can cause multiple issues, such as increased energy consumption and fresh water use, and the need to carry out hazardous and labor-intensive de-scaling operations.
Syensqo’s MAX HT® is a scale inhibitor that eliminates scale directly at the source. This sustainable, best-in-class solution reduces both energy and fresh water consumption, while cutting related costs, all in addition to addressing one of the alumina industry’s long-standing challenges.
A less emissions-intensive Bayer Process
Alumina, or aluminum oxide, is produced from bauxite ore and serves as the essential raw material for aluminum, the world’s second most widely used metal. It plays a key role in industries such as transportation, construction, machinery and consumer goods. Specialty aluminas are also used in advanced applications like ceramics, batteries, semiconductors and LED displays.
Today, most alumina is made using the Bayer process. This involves using caustic soda-enriched liquor to extract alumina from bauxite under high temperature and pressure. It’s an energy- and emissions-intensive process, which relies on large-scale heat exchangers to concentrate and heat the Bayer liquor.
One of the main challenges associated with this process is scale formation on heating surfaces, particularly heat exchanger tubes. As scale builds up, heat transfer efficiency drops, reducing throughput and increasing energy use and CO2 emissions.
This is where Syensqo’s MAX HT® Sodalite Scale Inhibitor makes a difference. By optimizing energy consumption, it helps lower emissions across the alumina refining process. It minimizes scale and impurities from evaporator and digester heaters during the Bayer process and maximizes heat transfer — hence its name, which stands for Maximum Heat Transfer.
Today, MAX HT® is used in more than 40 Bayer process plants worldwide, helping reduce energy use and minimize acid waste from heater cleaning.
A sustainable AND profitable solution
MAX HT® is a great example of how business solutions can be both sustainable and profitable. In recognition of its credentials as a solution that addresses environmental challenges without compromising economic growth, MAX HT® was named an Efficient Solution by the Solar Impulse Foundation in 2019.
“A rigorous methodology is used to evaluate products and technologies before they are awarded the Solar Impulse Foundation’s label as an Efficient Solution,” explains Ryan Zheng, Syensqo’s Global Marketing Manager for Alumina and Industrial Minerals, Mining Solutions. “This includes demonstrating that MAX HT® has a direct positive impact on the environment over its lifecycle, while delivering economic savings for customers.”
MAX HT® delivers on both fronts, improving energy efficiency and cutting CO₂ emissions by 13–92 kg per metric ton of alumina produced. When extrapolated across 20 alumina refineries, these savings represent an estimated 0.54-3.9 billion kg of CO₂ emissions, which is equivalent to about 20% of Brussels’ annual emissions in 2022.
“Leveraging analysis from current customers’ refineries, we demonstrated both direct and indirect financial savings for customers, which reduced their total cost of ownership,” adds Ryan. And what’s more, MAX HT® improves refinery worker safety, minimizing exposure to hazardous acid-cleaning conditions.
Alumina refineries in China now burn less coal because they don’t need as much energy thanks to our improved MAX HT®.
A scale solution just for Chinese alumina refineries
In China, the Bayer liquor composition is different from the one used in other regions. This is why we have also developed a specific MAX HT® line for the Chinese market.
“The Chinese market was using a lot more energy than necessary. Alumina refineries in China now burn less coal because they don’t need as much energy thanks to our improved MAX HT®,” explains Ryan Zheng, Global Marketing Manager for Alumina and Industrial Minerals, Mining Solutions.
In the early 2000s, the challenge of controlling scale in alumina refineries was considered unsolvable. Today, with MAX HT®, refineries can operate free from sodalite scale buildup in heat exchangers, significantly lowering environmental impact while saving billions of liters of freshwater each year — enough water to supply around 2,400 US households.
Syensqo continues to innovate with products that make mining and mineral processing more efficient, enabling customers to enhance productivity, reduce operational costs, and meet sustainability goals across the global alumina industry.
