Zinc oxide production by French process?

A. DEAR MR CHARKI UMESH MALLAPPA, I'm a Industrial Engineer working in a Plant in Pilar BUENOS AIRES (ARGENTINA) where we produce all types of Zinc Oxide by the French and American Process.
We recently installed a 7th line of production. I would very much like to contact you to exchange information over the whole process.

Yours sincerely

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A. Dear UMESH CHARKI,

Your problem of viscous Liquid metal in melt transfer of Zinc Dross is due to formation of ternary Alloy of Zn-Al-Fe.

The metal has to be pretreated and then remelted to be ready to feed for ZnO production.

A. Dear Readers,
I have just visited this interesting site. I have produced several research papers on ZnO French process and you may download for free as follows http://uk.geocities.com/shahromx/nano.html [Ed. note: that URL no longer works]

Have a wonderful day

Dear Paritosh,
1. For diesel oil combustion, you need to ensure perfect combustion from your burners - make air/fuel adjustment to get a blue flame. If this is not possible, make effort to clean the burners. If you still cannot get blue flame, check the quality of the diesel oil, it may not be pure.
2. Theoretically speaking, the maximum recovery is 124%. But it is impossible to achieve. Your 120% is good enough.

Cheers,

Thanks Shahrom ... but please e-mail those papers to mooney@finishing.com so we can offer direct access right from this site, rather than asking the readers to go elsewhere to get them. We've been on the internet since 1994 and were an electronic BBS for 5 years before that; so anything sent here will always work for the readers, but external links nearly always break quickly, littering the thread with unhelpful dead ends :-)

Thanks & Regards,

Dear Mr. Shahrom M,

This is the first time that I had a look at your Research papers on Zinc Oxide. The work is indeed very good and for a person like me who has worked on Zinc Oxide for more than 12 years it's a delight .

Would appreciate you keep us posted on your further work wherever you can, I mean where you have no secrecy/confidentiality issues.

----
Ed. note -- Sorry readers: as predicted, the link that Shahrom offered quickly broke. No links please! Please send whatever info you have to mooney@finishing.com for direct posting here; we have all the room in the world. Thanks.

A. For My above query about 'crucible-less furnace' I got more information From Dr. Peter Robinson (Canada) as follows,
ZnO will be produced in the furnace due to the Boudouard reaction-
Zn + CO2 = ZnO + CO

This reaction is at equilibrium at around 950 °C, at higher temperature, formation of Zn metal is favored.
Presence of ZnO will make process very difficult to control because there will be a cold interface with the liquid zinc.

Only direct heat method that I know of that is working is the Larvik furnace. This uses a resistance element above the zinc liquid. Cost of electricity is prohibitive in most cases.

I believe crucibles are the most cost effective route to ZnO. Crucibles need to be large, semi continuous liquid charged and configured for regenerative heating.

If anyone have such helpful information please participate in the discussion.
Thanking you all,

A. Dear Sumitji,
I am working as COO at a company in Mumbai. As per my knowledge we cannot form acicular zinc oxide directly by French process. I know about two processes, one is hydrothermal discharging-gas method, and second is flame spray pyrolysis.
You can find more about these processes.

A. Greetings CS Birla and fellow ZnO enthusiasts,
A million thanks for your interest in my PhD work on ZnO. In my work, I analyse the various primary particles that made up the ZnO agglomerates that are commonly found in gas phase synthesis and flame spray pyrolysis. It is true that you cannot obtain acicular structures from French process or flame spray pyrolysis. But I believe it can be done. From my research collaboration with one ZnO factory, we are able to produce acicular nano particles of ZnO at a rate of 1kg per hour. But the process is highly unstable and the quality of the nanorods are poor. I am now designing a novel furnace that can perform continuously (not batch type) and produce uniform nanorods of ZnO. Process parameters are the most important control variable especially the partial pressure of oxygen and the level of zinc gas supersaturation. For knowledge of this novel process some royalties must be affirmed.
Best wishes,

Ed. note: Please publicly share only what you consider non-proprietary, Shahrom.

Readers: As previously noted, this site is for public technical information exchange and camaraderie, and is made possible by our supporting advertisers. We ask that people not try to take the discussions private. Thanks!

A. Mr. Patil,
In French process zinc combustion is gas phase reaction, Which is controlled by concentration control (Partial pressure of gases) of both the gases. Also for burning of zinc totally zinc particles should be properly dispersed. One method is try to burn zinc totally by increasing oxygen partial pressure and after that you can separate zinc particles by using proper gravity settler. as zinc particles are heavier and larger than zinc oxide particles.

A. Dear readers,
Thanks you all as the discussion is going to be interesting. Following are some points in which I am giving answers.
1)Mr. Paritosh, Furnace production capacity is defined by zinc vaporization rate.Which is depend upon rate of heat input to the furnace.Heat required by zinc to vaporize (30 °C to 907 °C) is 540000 Kcal Per MT. On this basis your furnace efficiency is at 28-30%. You can improve furnace efficiency for lower furnace oil consumption.About recovery It is good kind of recovery, But can improved to 121.5%. by controlling byproduct generation

2)Mr. Sunil, In zinc oxide industry most of the furnaces are twin crucible furnaces. In this type. Heat distribution is equal and proper for both the crucibles. The Temp. required for zinc vaporization is 950 °C. So temp. difference ( Delta T) should be about 150 to 200 °C. For maintaining high temp. inside furnace, cooling of the flame should not be done below 1000 dg C.

3)Mr. Patil, Excess reactant is Oxygen, you can increase oxygen level by increasing conveying air. Which gives good dispersion for zinc particles and quenching to zinc oxide for finer particles. After that use better settler. You will find results after trial and error.

In case of anyone have different setup please share their experience.
Thanking you,
Umesh