Aluminum industry wake-up call: time for real-time cryolitic bath measurement

When it comes to heavy industry, some things don’t change quickly or easily, even when they can and should. Case in point, the aluminium industry has been talking about adopting real-time cryolitic bath measurement since 2010, if not earlier. 

Even so, the traditional bath measurement processes used at most aluminium manufacturers haven’t changed in decades. These consist mainly of the collection of bath samples for chemical analysis, combined with bath temperature measurements. And, most of the time, these two types of measurement aren’t even synchronized.

Relying on an outdated cryolitic bath process?

But can aluminium makers afford to keep relying on a such an outdated process when a better one is available? Some may say that it works well enough and that adopting new technologies won’t yield significant gains. It’s clear, however, that such logic has been proven wrong in many other industries over the past 20 years, thanks to digitalization.

The much more likely scenario is that increasingly advanced measurement systems will become necessary for Aluminum makers to stay competitive, while Aluminum pricing cycles up and down over the long run. Recent events seem to bear this out.

May you live in interesting times

There is an expression, perhaps wrongly attributed to the Chinese, which says “May you live in interesting times.” Times are certainly interesting now for aluminium producers. World market conditions are in a phase of readjustments. The outcome could profoundly affect the profits of aluminium makers worldwide.

Recent industry events

In recent years, China has massively ramped up its aluminium manufacturing capacity. It has become the world’s leading producer, in fact. In November 2017 though, the country began the process of cleaning up compliance and environmental issues. The temporary shutdown of certain non-compliant Chinese Aluminum producers has somewhat curtailed the country’s Aluminum production. Some industry watchers hint that the bans may become a yearly occurrence.

An opportunity for all producers

In the meantime, other Aluminum producers want to seize the opportunity that reduced Chinese production has given them. They see the expected rise of world demand, notably led by the automotive industry’s increased use of the metal. Some companies are building new smelters. Some companies are putting previously inactive smelters back online.

Aluminum prices are currently a bit higher which suits all producers. But what will happen once China is back to full production along with everyone else? Predictions, such as those of the Aluminum insider, are that prices will drop due to excess inventory.

Low prices will come around again

Whether lower prices materialize or not by the end of 2018, the aluminium market, like all commodity markets is cyclical and pricing varies. And when prices go low, profits suffer.

In such a context, making your production more efficient and less costly helps protect against such market conditions.

The limitations of traditional pot control

Traditional cryolitic bath control involves

  • Chemical analysis of the bath content. The aim is to get the right balance of chemical compounds. Adding AlF3 or Soda ash controls the chemical balance.
  • Bath temperature measurement. The right temperature for the right chemical balances will enable the bath to achieve optimal energy efficiency and optimal production. Adjusting the electrical current’s resistance (voltage) controls the temperature.

As stated at the beginning of this post, In the traditional method, chemical sampling and temperature measurement aren’t necessarily synchronized. Even if they were, the results from the chemical sampling come several hours after the fact. By that time, bath chemical composition and temperature may have changed.

This method can’t give you the exact state of the bath at any given time. This means that actions taken to optimize the temperature or chemical content will necessarily include a margin of error. Sometimes the margin of error is too great and bath efficiency becomes hard to control, leading to suboptimal performance and even to bath failure.  


A more advanced cryolitic bath measurement

the logical step towards better pot control and increased productivity is simultaneous, real-time measurement of both bath temperature and chemistry. Measuring temperature in real-time is relatively simple. The challenge is to be able to quickly assess the chemical composition of the bath.

This is possible through the analysis of bath sample cooling temperature curves. Thanks to a precise knowledge of the chemical properties of each of the bath’s chemical ingredients, it is possible to use cooling temperature curves to identify bath properties such as superheat, Alumina concentration and the ratio of Aluminum Fluoride to Cryolite. These four properties are really the key to knowing exactly what is going on in the bath.