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Zinc oxide production by French process?



A discussion started in 2002 & continuing through 2017

(2002)

Respected Sir,

I am chemical engineer working in zinc oxide plant, as plant manager. We are using French process for zinc oxide production. Our capacity is 10,000 TPA I would like to know more about French Process, with respect to productivity, controlling, cost and environmental cares.

Please do the helpful, thanking you,

umesh_charki
Umesh Charki
MetalliKon Consultancy Services - Thane, India



(2003)

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

Ignacio Olcese
- ARGENTINA


The World Market for Zinc Oxide and Zinc Peroxide

(2003)

Dear Sir,

I am glad to see your letter, recently in month of August 2003, I have installed a new furnace which is giving us very good performance. It consumes 100 lots fuel oil of calorific value 9200 Cal/ litre for one metric ton ZnO production and gives us 4MT production per day.

We are operating 9 furnaces of capacity 1.7 MT/ day for oil consumption of 200 liters / MT ZnO. Now with the new furnace we are able to operate with lower fuel consumption and higher production rate.
So that our own production capacity will be 1000 MT/ Month which we are now getting from labor job operations.

Please tell me about liquid metal feeding to French process furnace as we have tried but we can not work with galvanizing plant dross as this dross gives us very viscous liquid metal which is very difficult to transfer to crucibles.

Please revert back,
Regards, Umesh

umesh_charki
Umesh Charki
MetalliKon Consultancy Services - Thane, India


(2004)

Dear Sir,

We are interested in putting up zinc oxide plant using zinc dross as raw material. Any assistance shall be highly appreciated.

Thanks,

Sharad Patni
- Indore, Madhya Pradesh


(2005)

Hey Ignacio, I have recently joined my family business. The major problem we are facing right now is our high cost of production. I would like to know if you can help me out in this for our Zinc oxide Plant.

Here is my two specific questions

1) Right now we have a furnace with production capacity of 1.7 MT/Day - Oil consumption is 210 Liters (We use furnace oil for that) -- Can any one help me in that? as in how much we can improve our efficiency in terms of oil consumption(oil is the major cost)

2)Our recovery from special high grade zinc metal is 120% i.e., we get 1200 kg of zinc oxide from 1000 kg of metal -- can any one suggest what is the benchmark for that.

Awaiting your reply for these two question

Thanks,

Paritosh
- Udaipur, India


(2005)

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,

Shahrom Mahmud
- Penang, Malaysia


(2006)

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 pretreat and then remelt to be ready to feed for ZnO production.

Qaiser Majid

Qaiser Majid
    factory
Lahore, Pakistan



(2006)

Zinc oxide -French process-Is there any change in type of filter bags used? Dear Sir, We are manufacturer of Zinc Oxide in India through French process.

Till date we used filter bags made of cotton cloth.we have heard that there is some new technology, which replaces this filter bags with much advanced filter bags made up of some plastic like material.

We would like to know something about it.

Secondly we are consuming around 225 litre of furnace oil per M.T of Zinc oxide,we want to reduce it,kindly assist us.

ANKUR AGARWAL
- INDIA


(2006)

Sir,
I am interested in zinc oxide by French process. I have started this thread 4 years back , thanks to you all for the discussion.
Now I am interested in crucible less furnace for French process. in this process natural gas will be used as fuel. in this furnace oxygen level will be monitored by zirconia tip censor to prevent zinc combustion inside furnace. flue gas as well as zinc vapors will come out of furnace; which will be cooled using forced convection as natural convection gives bulky cooling systems and cooling efficiency also very low.
Benefit of the process is high fuel efficiency which is major cost of production. low downtime as crucible charging and cleaning is avoided. Zinc blocks of 2 to 3 MT can be charged in the furnace.in small place we can install furnace of 10 MT per day capacity.Furnace oil furnace is not giving efficiency above 40-45% but in gas fired furnace with direct firing will give efficiency up to 60-65 %.
If anyone is working in such technology please revert back in discussion.

umesh_charki
Umesh Charki
MetalliKon Consultancy Services - Thane, India


(2006)

Dear Sir,

We are leading manufacturing of French process Zinc Oxide our problem is that, we are not getting desired yield from metal as well as dross grade Zinc ,we have use SHG grade zinc ie.99.99% pure as per theory 1 MT Zinc gives 1.2447 MT of Zinc Oxide but we are getting only 1.2 MT Zinc Oxide and in case of dross we treat 94-95% Zinc dross in the furnaces we get only 1.1 MT Zinc Oxide please guide us how to get more yield in focus of which parameter.here dross grade zinc is having alloy of Zinc ,aluminum,and Iron some % of Lead please guide us melting temperature and conditions if there.

Regards,

DILIP .T.PATIL
- Daman


(2006)

Dear Mr.Shahrom Mahmud,

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 its a delight .

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

C.S.BIRLA
- Baroda, Gujarat, India


(2006)

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 Any one have such helpful information please participate in the discussion.
Thanking you all,

umesh_charki
Umesh Charki
MetalliKon Consultancy Services - Thane, India


(2006)

Dear All,

I am an IIT-Kanpur graduate and one of the directors at a company in India.

We are manufacturing zinc oxide by French as well as other processes, 20 tons/ day.

I would like to know if anyone has some idea how we can get acicular zinc oxide in the French or in the rotary process. This type of material is required by some speciality rubber compounding application.

Sumit Agarwal
zinc oxide manufacturing - Kanpur, UP, India


(2006)

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 process one is hydrothermal discharging-gas method and second is flame spray pyrolysis.
You can find more about these processes.

umesh_charki
Umesh Charki
MetalliKon Consultancy Services - Thane, India


(2006)

Sir,

Kindly suggest me Free zinc particles free Zinc Oxide by French process ,means how to controlled free zinc particles it is possible by proper filter cloth or something please guide me I await your valuable suggestion in this regard,

Thanks,

D.T.PATIL
- Daman


(2006)

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,

Shahrom Mahmud
- University of Science, Malaysia

Ed. note: Share only what you consider non-proprietary, Mr. Mahmud. We cannot expect the supporting advertisers who make this site possible to support postings that steer potential customers towards other people's services. Thanks.


(2006)

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.

umesh_charki
Umesh Charki
MetalliKon Consultancy Services - Thane, India


(2006)

Dear Mr Charki

We are manufacturer of Zinc Oxide and would like to know couple of things

1) Right now we have a furnace with production capacity of 1.7 MT/Day - Oil consumption is 210 Liters( We use furnace oil for that) : My questions is is this the right consumption or it can be reduced?

2) Our recovery from special high grade zinc metal is 120% i.e., we get 1200 kg of zinc oxide from 1000 kg of metal : Can you suggest what is the benchmark for that.

Thanks,

Paritosh
Director

Paritosh Mehta
- Udaipur


(2006)

Dear Readers

We are planning to set up a new zinc oxide production factory. We have designed a furnace with two crucible with the help of technician. many producers use only single crucible furnace. We are going to use dross as a raw material. Kindly let me know advantages and disadvantages of double crucible furnace.

Sunil Aghara
- Morbi, Gujarat


(2006)

Dear Mr. Umesh,

You are the expert in this, Is it possible to separate Free Zinc particles in our process Or other effective classification system is to be require please suggest.

Regards,

DILIP PATIL
- DAMAN


(2006)

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 degree C to 907 degree 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 dg C. So temp. difference ( Delta T) should be about 150 to 200 dg 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 the experience.
Thanking you,
Umesh

umesh_charki
Umesh Charki
MetalliKon Consultancy Services - Thane, India


(2006)

Dear All,

Discussion on French process is very fruitful and interesting for getting such valuable knowledge from all of you,

my question is that what is the best combination of input material in oil fired furnace normally top drosses are available available in domestic market it containing Alumina /Zinc alloys due to this only top dross charging is very difficult to use in the oil fired furnace what is the best combination of raw material to be use for getting desired yield and reduce furnace oil consumption please participate.

PATIL DILIP T.
chemist - India


(2006)

Hi Mr Patil,
Dross contains several percentages of iron and aluminium that have higher melting and boiling points. Iron and aluminium vaporise at 2862 and 2520 deg C, respectively; while zinc at 907 deg C. The final Zn-Fe and Zn-Al eutectics may have boiling points exceeding 1000 deg C, which may justify higher furnace oil consumption. Moreover the oxidised product may contain iron oxide and aluminium oxide that may produce yellowish/brownish tones to zinc oxide. You may use coke as a fluxing agent to lower the boiling point, and in doing so, you will be merging the French process with American process. Due to appreciable levels of impurities in this French-American zinc oxide, potential applications would be lower end ones.
Regarding fuel supply for crucibles, I suggest that you use electric heating in the form of SiC globars that are heavily used in many furnaces that I used to work with, whereby the process efficiency can double. There is no heat loss via exhaust duct since there is no exhaust. Most of the heat produced by the globars is transferred to the zinc ingots. You may need 8 SiC globars for each furnace at a price USD 300 per globar (I think) excluding the control panel, and the globars can last for 10-12 months.
I hope you will find my suggestion fruitful.
Best wishes.

Shahrom Mahmud
- Penang, Malaysia


(2006)

Dear all,
I am a Spanish Chemist, and I am interested in putting up a zinc oxide plant. It is a new project for my company. We would use zinc dross, including zinc powder. Any advise about the implementation would be highly appreciated.
Best regards,

MARIA ABELEDO
ZINC PLANT - Vigo, Pontevedra, SPAIN


(2006)

Dear Mr. Shahrom Mahmud,

We highly appreciate you for attempting,

We are using Oil fired furnace that place couple of silicon carbide crucibles its heat up through burner- Furnace Oil as a fuel.
Please suggest us for use of fluxing agent (as coke) at what temperature along with its conditions.

Regards,

D.T.PATIL

PATIL DILIP T
- DAMAN


(2006)

dear sir,

we are manufacturers of Zinc Oxide by using French method,
use Zinc Dross of 94-95% pure.Now a days as Zinc Dross /metal price go big higher we are looking for cheap replacement as in our another unit of Ceramic raw material we are consumer of Zinc Oxide.

is it possible to produce Zinc oxide from Zinc Hydroxide ?

we have some source of Zinc hydroxide which is byproduct for them so it is cheap also.
please explain.

Kantilal Patel
- Morbi, Gujarat, India


(2006)

Dear Mr.Kantilal Patel,

Ceramic manufacturer are using french process zinc oxide because this zinc oxide is amorphous white in colour.Oxidation process from hydroxide rout Zinc Oxide colour becomes yellowish and after calcination pulverisation is also require. Yellow zinc oxide is suitable for Tyre and rubber compounding but it is also depending upon process control parameters ,Surface Area, Purity and other impurity level ,I think French process is better option for Ceramic application.

D.T.Patil.Daman

Patil D.T.
- Daman


(2006)

Re calcination of yellow zinc oxide -
before I started work on ZnO (and that's some time ago)the company where I worked used a small addition of sulfur to reduce the grittiness caused by calcination. The process had already ceased when I joined the company so I have no actual experience of this possibility.

Peter J. Robinson
- Fergus, Ontario, Canada


(2006)

Greetings fellow ZnO enthusiasts, With respect to calcination of yellow ZnO, a possible route to reduce grit levels may be to add around 0.5% of sulfur powder to the ZnO before calcination. This practice was used decades ago with French process ZnO to make product suitable for paint coatings. I have no first hand experience of this but understand it was a commercial process that operated for several years. (Apologies - my earlier submission slipped away before I had chance to add to it)

I have seen electron micrographs of calcined yellow (hydrosulfite process) ZnO. Rather than calcination (coalescing of individual particles), the mechanism appears to be re-formation of the ZnO with a different crystalline structure. Although the material was white it had an unacceptable level of grit for most applications,

For readers with a keen interest in the early development of the Zinc Industry, I found an interesting paper describing archeological work carried out in India-

http://metalrg.iisc.ernet.in/~wootz/heritage/zn.html

Many thanks

Peter J Robinson
- Fergus, Ontario, Canada


(2006)

DEAR SIR,
I will appreciate if you could help us about this problem.
we have a ZnSiO4 mine to produce ZnO out of this soil we have built a site with wales furnace.
we are planning to produce ZnO with 60% purity.
would you give us the information of a suitable method for extracting ZnO from ZnSiO4 soil and whether is our method (wales furnace) alright or not?
thanks.
best regards,

ZAKERI,HADI
- IRAN


(2006)

Re zinc silicate orebody & extraction process

Most modern mode of operation for a zinc silicate concentrate is to use solvent extraction techniques as used at the Skorpion, Namibia zinc mine, for example. The decision to use this technology rather than a Waelz kiln will depend on other factors such as the other metals of value that may be present and also the scale of the operation.

Peter J. Robinson
- Fergus, Ontario, Canada


(2007)

Dear friends,

We are using zinc metal for manufacturing of zinc oxide with lead, <20 ppm as required by the Indian Pharmacopoeia. However due to steep rise in price of zinc metal we are unable to be viable. As such material is available at prices slightly higher than that made from dross, means that dross can be used for making pharma grade lead-free material.

Could you help me with the process parameters for producing this kind of material from dross? Any kind of guidelines would be greatly appreciated.

Sometimes we do get this material from dross but that is a very rare chance.

Regards -

Sumit Agarwal
zinc oxide manufacturing - Kanpur, UP, India


(2007)

Q. We are a dental material/cosmetics manufacturer and we consume zinc oxide pharmaceutical a lot. Due to price increase of this material the cost of our production has gone up and we are not competitive anymore.
We have zinc metal available in Iran and also fuel as well as low wage labour cost in Iran leads us to contemplate to produce this material in our plant.
We will appreciate a lot receiving proposals/guidance/suggestion enabling us to decide.

ABBAS MORADIAN
- TEHRAN, IRAN

(2007)

Q. Production of 95% ZnO

Dear all friends
I am already producing ZnO (99.97%) from French Process. I need to develop a process for ZnO (95%)-Low purity.
Can you suggest me?

Ishtiaq-Ur-Rehman Siddiqui
chemicals - Lahore, Pakistan

(2007)

A. I work for an international company that manufactures ZnO as well as many other products.

We routinely recover 122% ZnO from HG and 110% from galvanizing top dross. These conversions are achieved whether using a 2 MT per day furnace or a 30 MT per day furnace.

At one time our organization thought 120% was adequate, but we have learned to achieve better results.

These results were not achieved overnight, but through years of improvements.

Latti J. Wood
- Pittsburgh, Pennsylvania


(2007)

Q. Dear Sir,

We are interested in putting up zinc oxide plant using zinc hydroxide (a byproduct of sodium formaldehyde sulfoxylate) as raw material. Any assistance shall be highly appreciated.

Thanks,

Nilesh Shah
- Baroda, Gujarat, India

(2007)

Q. Hi, Friends:
I meet a problem in manufacturing the high purity (>95%) of zinc oxide and looking for help:

The problem is zinc oxide always containing 2~3% of lead oxide which we hope to reduce to <1%. Our manufacture is dry process. Right now our only solution is control the ore quality, but it is very difficulty and costing.

Any idea, Please help !

We also looking for expert who have interesting to open the business in manufacture Aluminium Oxide in China.

Jianmin Shi
Chemist - Rockville, Maryland

(2007)

Hello,
we have been manufacturing zinc oxide (lead free grade, electroplating grade,silver seal,white seal, 99.5%- 99.9%) for the last 15 years and with the hard work of all our employees and well wishers have been able to live up to the expectations of our valued customers in delivering a quality product.

Now we want to start manufacturing active zinc oxide through wet process. we are totally new in this field and any kind of help in this regard ( process of manufacturing, raw materials and substitutions, applications, discharge of effluents and wastes, recycling of wastes etc)would be duly appreciated. people who are already into this should please forward their experiences so that we can also learn from their valuable ideas and experiences.
please share your ideas.

Thanking You,

G.S. RANDHAWA
CEO - RAJPURA , PUNJAB, INDIA

(2007)

REALLY NICE TO FIND SUCH A ONLINE GROUP.ANYWAY PLEASE ALL READER ARE REQUESTED TO PROVIDE US WITH YOUR SUGGESTIONS.
WE ARE MINING ZINC WHERE WE OBTAIN THEM IN THE FORM OF LUMPS WHERE WE WASH,PULVERIZE,DRY AND PACK THEM.IT IS WHITE COLOUR POWDER ZINC OXIDE WITH ZnO - 80% AND ZINC Zn ALONG 65+ ALONG WITH THIS WE ALSO FIND LEAD Pb - 3 PPM,MAGNESIUM Mg-7%,CALCIUM Ca - 4%.WE UNDERSTAND AND AWARE ITS REALLY A RARE FORM OF DEPOSITS.

ANYWAY I WISH TO KNOW FOR WHAT ALL PURPOSE THIS MATERIALS CAN BE USED?

CAN ZINC METAL BE EXTRACTED BY USING THIS AS RAW MATERIALS. CAN THIS BE CONSUMED OR USED BY CHEMICAL INDUSTRIES TO PRODUCE HIGH GRADE ZINC OXIDE.

IS IT POSSIBLE FOR US TO PRODUCE HIGH GRADE THAT IS 99.5%+ ZnO - IF SO UNDER WHAT METHOD WE HAVE TO MAKE A PLANT.ALSO PLEASE PROVIDE ME YOUR VALUABLE SUGGESTIONS.

THANKING YOU,
REGARDS,

Vairavan Lakshmanan.
DIRECTOR - INDIA

(2007)

Dear all,
we are leading manufacturer of Zinc Oxide in India by French process. we are using raw material zinc dross containing impurities like Pb, Fe, & Al We are facing problem for raw material containing higher % of iron (Fe) i.e. up to 4-5% when we charge such material in a crucible, saturation of Iron takes place at bottom of crucible after 2-3 duty crucibles volume get decrease. I want to know is there any specific flux available for removing iron content from crucible.if it is please let me know. your information is highly appreciated.

Ravi Rajput
Q. A. Manager - Jammu, India

(2007)

Dear MARIA ABELEDO,
As you are new in this zinc oxide mfg. field you have to take care for lot of things like raw material quality,Suppose If you are using raw material containing higher impurities like Lead & iron it will affect your product as well as increase the f. o. consumption . Most of impurities will get settled at the bottom of crucible which increase the thickness of crucible & due to increasing thickness consumption of F.O. consumption will increase.Secondly process parameter is most important you should have control on your process parameter like evaporation period, Blower RPM, collection of Zinc Oxide at diff tank etc. Thanks

Ravi Rajput
Q. A. Manager - Jammu, India


(2007)

Please can anyone tell me what is exactly the French process of making zinc oxide of 99.99% purity with zinc dross.Where can I get the plant and machinery from.And what will be the cost for 10 MT/day plant.
Thanks

Shaurya Mittal
buyer - Ludhiana, Punjab, India

(2007)

Dear Ravi Rajput,

This is the problem of all zinc oxide manufacturer but nobody can search this type of flux.you have two way to avoid the problem, first you take furnace cleaning after 3 days, second you blend the material like top and bottom dross and lower impurity with higher impurity material.
then you feel 80% realisation.

R.R.Yadav

Ramashare yadav
zinc oxide - India


(2007)

Dear Mr Shaurya Mittal
Zinc oxide was discovered by Cramer in 1750 while the French process was popularized by LeClaire in 1844 during when he mass-produced ZnO for white oil paint. Pure zinc metal was used then. The use of cheaper zinc dross has been popular lately due to the zinc high price LME of USD 3440 per MT. However the French process is not designed for recycled raw materials since there is no convenient way to leak out the accumulated dross impurities during operation, i.e., there is no leaking valve on the crucible. If there exist a crucible with a leaking valve, it would have lower working life due to intricate design. Dr Robinson and I suggest that the best practical way is to purify the dross to a purity of above 99.9% zinc before charging into the French process furnace, meaning a purification plant is required.
Best wishes,

Shahrom Mahmud
- Penang, Malaysia


(2007)

Dear Mr. Shahrom Mahmud,
For producing zinc oxide 99.9% pure from dross, can we go by using self-refluxing column for fractionation of incoming vapours. As new jersey process is used for zinc fractionation with external refluxing of liquid zinc and the purified zinc vapours are condensed to get pure zinc above 99.9% purity. The same process can be used for purification of zinc vapours and subsequent oxidation will give us pure zinc oxide. This oxidation will happen far above floor level so contamination of atmospheric dust (foreign particles)will reduce. Instead of purifying zinc dross to zinc metal, this process will help for lower cost manufacturing as energy is major part of manufacturing cost.
Please revert with your valuable inputs upon this issue,
Thanking you,
Umesh

umesh_charki
Umesh Charki
MetalliKon Consultancy Services - Thane, India


(2007)

Dear Mr Umesh Charki,
I agree with you that the best way to purify zinc dross is by vapourising it. If you can build a furnace that can vaporize dross into vapours, you can oxidize it to make ZnO and you can obtain a good purity if you oxidize the vapour far above the ground level, as you said earlier; however, the particle size and morphology will be different than that obtained from French process. The French process is based on high velocity zinc vapour at speed of Mach 0.1 followed by rapid air-quenching. ZnO size and morphology are highly sensitive to temperature and Zn/O ratios. You may have to spend money and time to experiment on several furnace designs in order to simulate the French process. Perhaps you need professional help to expedite results.
Good luck.

Shahrom Mahmud
- Penang, Malaysia


(2007)

Dear Mr. Shahrom Mahmud,
Sir, I have tried this process in 500 Kg/ day furnace for experiment trials. We got 5.5 square meter per gm with 99.86% zinc oxide. 65% of total production by the setup was of this grade. lead was 16 ppm. Dross used for this trial was 94.5% zinc with lead 0.4%, which is normal grade of dross available.
Sir, I was working as COO with one of the leading zinc oxide manufacturer in India. I have installed 24 zinc oxide furnaces in last 5 years and 6 for zinc metal recovery. I have tried zinc metal distillation, zinc dross to zinc metal for experiment which gives 93% recovery of 99.3% pure metal from dross. All these experiments are carried on 500 Kg/ day capacity furnace. Scale up of these trials on 4 MT/Day furnace is easily possible as equipment sizing is already completed.
I am also interested in nano zinc oxide by hydrothermal discharging-gas method and second is flame spray pyrolysis.
As nano zinc oxide is in increasing demand for various applications.
Anyone who are working on the same please share.
Thanking you,
Umesh

umesh_charki
Umesh Charki
MetalliKon Consultancy Services - Thane, India


(2007)

Hello Umesh,
You have done great engineering innovation by building your own distillation furnaces for zinc recovery from dross. To my knowledge, flame pyrolysis has not been commercialized yet. There is one professor from ETH Zurich, Prof Pratsinis Sotiris, who has been doing flame synthesis on ZnO for many years. You may contact him for advice from this link http://www.ptl.ethz.ch/people/director/pratsinis . He has synthesized nano particles of ZnO at a lab scale.
Good job!

Shahrom Mahmud
- Penang, Malaysia


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