NOTES

  • The process calculations were reviewed by Dr Ashot Navasardian
  • The process parameters were validated by the Zn. I was checking the results by adding the Zn, because the Zn was researched already – Purification of the Al2Cu intermetallic compound via zone melting crystallization technique.
  • The process was calculated for the Gold
  • Why zone melting – because the process is well researched and not widely applied, so the AI could bring it to the market and make it effective

MY OPINION

  • The ChatGPT understands the refining processes, but you need to be very specific and clear with the external procedure. AI doesn’t know the traditions for the applications.
  • Of Course you can not rely on not proven data, but you can compare the results and make projections many times faster. My opinion the AI predicts future trends better than others.
  • The AI sees the zone melting process the way you tell it. Be specific what is the molten zone.

 

What is the zone melting?

The zone melting is the process that is unique because it can purify all elements from 95% till 99,999%; 99,9995%; 99,9999%. The process is very simple – different impurities have a different solubility ratio, so simply melting the metals at specific areas and moving the area, the impurities move with a molten zone or they could go in the opposite direction.

I used the term zone melting many times in my previous articles and time to explain the process and its limitations.

  • The process is very slow – 0,7 till 1,5 mm per minute. It takes a day to make a single pass, while you need 6-15 passes to get the required purity and crystal structure.
  • The process is not effective if the metal has high thermal conductivity. My advice is don’t use it for copper and aluminum. For aluminum it was widely researched and applied but  I suggest using solvent refining to remove impurities that have high solubility first.
  • The density. More heavy it is more cost effective the process
  • Melting point. Example – the same furnace and power consumption purifies 1 000 of the tin and purifies 10 kg of the aluminum.

The process is not the answer for sustainable high purity metal production, if we don’t take into account the vertical floating zone melting furnaces – the best zone melting you ever see, but as a stage for the many processes is one of the best technologies that ever was created.

It is really hard to explain, but the fact is – zone melting is not good for the aluminum but the most research was done specifically on aluminum

  • Study on the behavior of impurities in zone melting of aluminum Mengping Duan, Jinyang Zhao
  • Alternative fractional crystallization-based methods to produce high-purity aluminum Danilo C. Curtolo, Martin J. Rodriguez-Rojas

Ok, how to make it selective?

Copper Zinc case study

When the zone refined material is compound – Al2Cu the Al, Cu will not change its concentration. So, once the compound is synthesized it is impossible to purify it by zone melting. However the remaining impurities are easily removed from the system. Some impurities form compounds while some of them just stay in the system. The example is Bismuth – Gold – Silver. Gold – Bismuth compound, Bismuth – Silver – solution. The system Copper – Zinc – solid alloy. The zone melting process is not effective to remove the Zinc. The high thermal conductivity and segregation coefficient of the Zinc is close to one.

How is it different? Same power, heater, furnace

  • So, It could take 20-30 passes to purify couple 5 kg
  • Add, Al and it will take 2-3 passes to purify 50 kg

How could Aluminum change the process? – It changes all segregations coefficients

The Al2Cu is compound because the Al and Cu is not changing the concentrations while zone melting.

Cadmium Tellurium case study

Firstly the segregation coefficient for all significant impurities for the elements separately and the compound form.

Now a little bit ChatGPT to verify its understanding of the impurities

Segregation Coefficients of Impurities in Te, Cd, and CdTe

This shows very clearly that the segregationally coefficients are different for the compound and for the elements separately. The same for the thermal and physical properties.

How to apply zone melting, my personal understanding for the process and its requirements for the sustainable business

My personal notes are include

  • Thermal conductivity lower than 100
  • Melting point lower than 500
  • Density higher than 5 000
  • 99,999% / 99%  – Price ratio 5x

Typically it is enough for me to make a decision whether to apply solvent refining or not.