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Zinc oxide production by French process

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A discussion started in 2002 but continuing through 2019

March 10, 2009

Dear all,

One of my client asked me to provide ZnO granules, can any one help me to develop the same?

Regarding my research I found that we can make granules by two ways one is pre dispersed and other is by palletizing, please advise with your best knowledge.
Thanks and regards

Suvneet Kalsi
- Delhi, India

March 11, 2009

Dear Suvneetji,
Zinc oxide granules are less preferred in Indian market as no one is paying extra for granulated zinc oxide. There is no value addition.
Zinc oxide granulation is done by compaction (palletisation). white seal zinc oxide passed through rollers with 250 Kgs/cm2 pressure and formed flakes then broken in desired size. Here some times additives are used for particular applications.
Zinc oxide granulation by pre dispersed method is manufactured for particular application. As in rubber manufacturing rubber(elastomer) and zinc oxide is mixed in particular ratio and while compounding this ratio is adjusted.
As compaction granulation machine cost from 15 lacks to 1 crore. In India 2 or 3 manufacturers are doing this process.


Umesh Charki
MetalliKon Consultancy Services - Thane, India

March 17, 2009

Dear Sir,

I am researching about the production of ZnO from Zn(OH)2 I wonder if you could tell me what is the optimum calcination temperature. I worked at 650 ºC but the mass loss was huge, not only the corresponding to the molecular mass difference between ZnO and Zn(OH)2.

Thank you very much for all your attention.

Diego Herrero
Researcher - Bilbao, Spain

March 31, 2009

Dear Mr. Diego,
In India, We are producing Zinc oxide by decomposition of Zn(OH)2. Actual decomposition temp. is 500-600 °C. But it contains sulphur compounds, which required 950 C to decompose.
If mass loss is more than material balance. then review your calcinator design. It is normally rotary kiln with direct heating. But flow pattern inside kiln matters, as material carry over happens. Proper sizing and design of the furnace is important for desired results of conversion and yield.
In this issue I found good article on internet,

Umesh Charki
MetalliKon Consultancy Services - Thane, India

April 8, 2009

Thanks for your all support.

As we are planning to make Zinc oxide granules, we don't know what kind of binder we shall use to have some hardness.

I want to try with st. acid, only worries is for that we have to melt S.Acid first during feeding into granulator, I have a query regarding the reaction between ZnO and S.Acid. Does it react enough to loose their basic properties as an activator in rubber compound.

Thanks and Regards

Suvneet Kalsi
- Delhi

April 9, 2009

Dear Suvneetji,
Stearic acid and zinc oxide reacts but at 5 kg/cm2 pressure and 140 °C. This reaction forms zinc stearate melt. Or zinc hydroxide and stearic acid directly reacts to produce zinc stearate in powder form. Zinc stearate used as lubricant in tire manufacturing.
Mixture of both compound is not reactive.
Binder materials used in zinc oxide are as per application. These materials used less than 1% in zinc oxide. You can try natural gum in dilute form. and sprinkle it in rotary drum filled 30% with zinc oxide. this is one type of granulation I have seen; but after it is to be dried.


Umesh Charki
MetalliKon Consultancy Services - Thane, India

February 6, 2010

Now our company is dealing with zinc oxide that is being produced through French process.the company is going for expansion and is looking to introduce new methodology in this field.
The company is looking for introducing new method of production .it is planning to introduce active zinc oxide, but we are not able to get the technical know to produce active zinc oxide
Please help me this issue...
Thanking you

Hemanth Ravindran
- Bangalore, Karnataka, India

June 11, 2010

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


product designer - IRAN

June 16, 2010

Dear Mr. Sattari,
This is the same message I posted at start of this discussion. If it the same question from your side, then it is very difficult to answer in one answer. You can go through the total discussion to understand different aspects of zinc oxide manufacturing.
In case of any specific question, please ask.
Thanking you,

Umesh Charki
MetalliKon Consultancy Services - Thane, India

Ed. note: Exactly, Mr. Charki!

Mr. Sattari: Please study the thread and keep the discussion moving forward. People sometimes ask why we still recommend technical books in this Internet age, and your posting demonstrates that the Internet sometimes just runs you in circles :-)

June 16, 2010

Thanks for one and all for the information you are providing on this forum.

I am planning for 1000T capacity Zinc Oxide plant, can I get some information like

1. Who can do the erection and supply the machinery for manufacturing ZnO
2. Rough estimation for 1000T capacity
3. Whether to go for 500T or 1000T capacity



sai chennupati
- Hyderabad India

June 22, 2010

Dear Sirs,

I would like to know, what is the common process used to convert galvanizing zinc ash/dust into zinc oxide with higher purity. Is the only way to do it hydrometallurgical, or are there pyrometallurgical ways to achieve the above.

Thanks in advance for the answers.



Hemanth Vijayan
- Lagos, Lagos, Nigeria

December 20, 2010

Our consumption of furnace oil is 225 liters in manufacture of Zinc Oxide. Please help us on how to reduce the consumption?

sahil gupta
top management - haryana india

January 8, 2011

To reduce furnace oil consumption, Furnace should be developed to save heat energy. This is done by proper designing of furnace, suitable and good quality insulation of furnace, Proper temp & pressure of furnace oil, Heat saving equipment such as heat regenerators in furnace.

Umesh Charki
MetalliKon Consultancy Services - Thane, India

February 9, 2011

Can we manufacture zinc oxide without crucible?

Irfan Darogha
- Gujranwala, Punjab, Pakistan

February 5, 2011

any one can tell me whether zinc oxide powder can be packed by automation.
If so, please inform the details.

partha sarathy
engineer - Chennai, T.N . India

February 16, 2011

Dear Sir,
1)For My 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.
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.

2)We can pack zinc oxide in automated system, only we have to workout on economy. Presently we pack 25Kg oxide precisely in HDPE bags. Machine with this kind of precision is costly. We use 2 labors for oxide unloading, packing, weighing and stacking 5 MT oxide per 12 hr. shift.
This is possible by proper and simplified mechanization of system.

Hope your queries are solved,

Umesh Charki
MetalliKon Consultancy Services - Thane, India

February 22, 2011


We currently have installed capacity of 300 MTs per month.

Can we run 2 furnaces with same capacity together ? If yes is there any other change to be made in the plant & machinery.

Ritesh Kumar
manufacturer - Karnataka

March 11, 2011

Thanks you all as the discussion is going to be interesting, I would like to know how to controlled insoluble particle in a acid solution. we have customers having specification of CLEAR SOLUTION , it is very difficult to obtain clear solution.

Ravi Rajput
Manager Q.A. - Palghar

March 14, 2011

Dear Mr. Ravi,
Insoluble are dust and ash in zinc oxide. This impurity is mixed with zinc oxide at suction point on furnace. You can avoid insolubles easily by following steps,
1) Maintaining clean furnace area, ash free.
2) If using furnace oil, try to block and avoid black suit generations and leakage at furnace top.
3) Avoid skimming, crucible cleaning when process blower is on and suction on furnace.
These are easy steps in operations to avoid insolubles. Also you can use settlers efficiently to separate heavy impurities.

Umesh Charki
MetalliKon Consultancy Services - Thane, India

June 15, 2011

I am interested to learn more about controlling factors in running a furnace to manipulate the ZnO powder produced, especially in the parameters of lower particle sizes and with low surface areas at the same time. I know there are a few different crystal structure of ZnO particles which would explain why I am currently only able to manipulate my surface areas but always in the combination of larger particles giving lower surface area but smaller particles having higher surface area. What I need to produce is smaller particles size with low surface area.
what kind of furnace and suction blower parameters do I need to control?

Mervyn Goh
- Rawang, Selangor, Malaysia

August 24, 2011

Dear all.

I'm a student and I'm trying to produce zinc oxide from an electric arc furnace dust. I actually have zinc hydroxide and I want to furnace that, but I'm not sure of what temperature is the best to do it, can anybody help me, please?

Thank you!

Daniel Palacios
- Monterrey, Nuevo Leon, Mexico

August 29, 2011

Dear Mr. Daniel Palacios,
There are two different things you are asking for?
1) electrical arc furnace dust contains Fe, Zn, Ca, Si etc. Out of which Zinc (in oxide form) is vaporized after carbothermal reduction and further oxidation to zinc oxide. this is done in Wealz process in rotary kiln. This process increases concentration of Zinc content and separate it from Fe impurity. Wealz zinc oxide is further processed to get electro zinc or zinc chemicals.
2) To convert zinc hydroxide to zinc oxide, we use rotary kiln and temp. required for hydroxide to convert to oxide is @ 480 to 550 °C. In certain cases if hydroxide contains sulphur then temp rises to 950 degree to remove sulphur compounds.

For more queries you are most welcome,

Umesh Charki
MetalliKon Consultancy Services - Thane, India

September 16, 2011

Dear Sir,

I am dealing with wet process zinc oxide by ammonium carbonate (us patent 4071357) . We have to make project on a chemical plant.

So I have selected ZINC OXIDE POWDER making plant which is useful in making zinc oxide active.

I have to make total process for making zinc oxide powder(wet process).
I have some of the question regarding this which are as follows

1) What is the process of making zinc oxide powder(wet process)?
2) What type of machinery is required for making it?
3) From which Material it requires?
4)The product purity is 97% to 98%? Why Opaque white or yellow color is?
5) Where can we use it? (state all the useful area)
6) If you have any picture of plant, please send it to me?

Please provide me all guidance about wet process zinc oxide plant, process, equipment required, and uses.
I will be very thankful to you if you are answering my questions.


Arash akbary

arash akbary
chemical - iran tehran

September 16, 2011

Dear Mr. Arash Akbary,
The process you are using is Ammoniacal ammonium carbonate leaching method. This method is used as recovery is maximum in this method. And we can recycle Ammonia again and again. In India there are plants using same method.

1) What is the process of making zinc oxide powder (wet process)?
There are different wet processes for making of zinc oxide. You can leach zinc from zinc bearing waste (mostly non-metallic) using different acids. Purify the solution and precipitate in the form of zinc hydroxide or carbonate. Filter and dry the precipitate and further calcination produces zinc oxide. Wet process is mainly used for non-metallic waste of zinc.

2) What type of machinery is required for making it?
Plant and machinery includes reactors, filters, centrifuge, dryers, calcinators. In Ammonium carbonate we need steam distillation column (ammonia strippers).

3) From which Material it requires?
Zinc ash from galvanizer, waelz oxide, other zinc bearing waste. It has wide scope for zinc recycling.

4) The product purity is 97% to 98%? Why Opaque white or yellow color is?
Pure zinc oxide is opaque white powder. Yellowish color is due to impurity in oxide. The purity we check by checking Zn+ and then calculate for zinc oxide. But if there is zinc carbonate purity indications become wrong. You can first calcinate sample at 900 °C and then check for purity. Even then sample is lower in purity then there are some impurities and the purification of zinc solution is not done properly.

5) Where can we use it? (State all the useful area)
Zinc oxide has wide applications. But calcination of zinc carbonate gives high surface area zinc oxide having application in catalysts and desulphurization in petroleum industry.
You can refer the article from Iran

For more questions you are welcome...

Umesh Charki
MetalliKon Consultancy Services - Thane, India

October 24, 2011

Dear Respectable & honourable personalities.

1. We need to know about how we can reduce our gas expenditure?
2. Is there any other way without crucible to reduce expenditure.

Your response would be appreciated.


qamar zaman
gujranwala, Pakistan

November 1, 2011

Dear Umesh,
1.We need full information about f/o adjustment all specific surface area because we are adjusting new crucable on this is our new experiment on f/o. your co-operation will be appreciated.
2.which one suitable burner for f/o.
3.what will expense on 1 mt for f/o.
your cooperation will be honourable.

Qamar Zaman
- Gujranwala

November 30, 2011

With respect
Mzahmtvn Myshm of Iran. I want a series about the production of zinc oxide. In the case of slag in the production process and also produces zinc oxide Mytvnym do?

Ali Reza Roozkhosh
- Maybod, Yazd, Iran

June 27, 2012

Q. Dear Sir,

How can I make fine particle size say 2-6 microns ( 100% particles <37 microns) and 7-10 microns ( 100% particles <45 microns) zinc dust from atomised zinc powder having average particle size 15-19 microns( with 85% particles <45 microns and 70% particles <37 microns).
we have tried air classification , but PSD not achieved and recovery was around 25% only. Is this due the inadequate air supply to carry the zinc powder? The bulk density of zinc powder is 3.5-3.7 g/cc. Can you please tell me whether classifiers can be used to get the specified products with 90% recovery[ w.r.t the available fineness]? If so what may be the critical process parameters for classifiers?

Thanking You


Neelakandan Santhosh
- Keral, India

July 26, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hello.
Sir, I want to know how to make zinc dross and zinc ash?


July 30, 2012

thumbs up signGreat information sharing, thank you.
Based from thread, we can produce 120% ZnO from Zn.
Interested to know theoretically how much diesel oil an efficient furnace uses for 1 mt ZnO.

Balakrishnan Maniam
- Seremban, N.S.D.K, Malaysia

August 25, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Sir,
Zinc oxide production by French process. I want to establish a new plant for production of Zinc oxide. Can you suggest me it's viability & technologies in detail and also help me to prepare me a project report.

New entrprenur - Jaipur - Rajasthan(India)

September 10, 2012

Q. Hi,

We are planning to enter into manufacturing of Zinc Oxide Powder in/around Hyderabad. Please advice us with the advantages and disadvantages.

We would also like to know the manufacturing process for the same.

S K Ganeriwal
- Hyderabad INDIA

October 14, 2012




arash akbary
behinehsazan - tehran iran

October 13, 2012

Q. Myself Ravi Girase working as a Q.A. Manager from last 12 years with pioneer in producing white seal Zinc Oxide. I want to ask about Furnace oil consumption what will be the ideal F.O. consumption for producing Zinc Oxide by using Zinc Dross produced from galvanising industries.

Ravi Girase
Zinc Oxide - Daman, India

November 12, 2012

Q. Dear Sir:
Please be informed that I am interested to know about the properties and quality and long term performance of different types of ZNO blocks used in surge arrester manufacturing ... and about micro and nano grains used for making ZNO blocks.
Hope to be hearing from you soon and in detail.
Best regards,

Reza Tousipanah

May 24, 2013

Q. Hello Mr. Umesh Charki.
Your information and experience about ZnO is extraordinary and giving this precious information without expectation is excellent.

I am a chemist and want to MANUFACTURE ZnO and have some questions:
1- is it possible to MANUFACTURE ZnO in a workroom?
2- is it possible to cool vapor of ZnO naturally without water?
3- during calculation that I made the time for vaporizing Zn then melting Zn approximately is 8. But after melting Zn I can't vaporize it. Why?
With best regards,

meysam nikmoradi
- maryanaj, iran

December 16, 2014

Q. Dear Sir,

I did my graduation in metallurgical and materials engineering. I want to manufacture ZnO; have some Questions regarding it...

1. Approx. cost (excluding land) to set up a 1 or 2 MTPA ZnO manufacturing plant (through French process)?

2. Running cost of plant?

- Sardarshahar,Rajasthan,India

November 30, 2015

Q. Dear Sir,

We have the Zinc Oxide First Chamber material approx. 250MT in Quantity. The Spec is like 90-95% as Zinc Oxide , Sieve residue - 5-8%, Lead Content is 100 - 2000 ppm and other properties are same as of like Normal Grade or White Seal Grade.

Due to high sieve residue this material is accumulated with us from last 2 Years.

Please advice any Process to remove the Grit from this Material (We have applied the Vibro Separator to this material but the results are not so good.) or please suggest any type of customer who can consume this material.

Vikas Das
smelting & refinery rorks - Yamuna Nagar, Haryana

Ed. note -- Readers: Please note that Vikas has requested to know "type of customer", not specific customer names. This site is for camaraderie and technical information exchange only. We do not put readers into personal contact, nor post any commercial responses.

Possible to make zinc oxide from fine zinc dust?

April 30, 2016

Q. Dear Sirs.
To all you people that make this thread so interesting.
A company has developed a good economical and quality process to recover Zinc from the Electric Arc Furnace; they produce a very fine dust and a 99.98% of Zinc.
My big question; it is possible to produce Zinc Oxide from a Zinc Dust?
I will appreciate all information.
Regards, Bernard

Bernard Mulet
zinc - Guatemala

Reducing iron oxide in zinc sulphate

September 7, 2016



September 28, 2017

Q. Dear Sir
We are leading manufacturer of white seal zinc Oxide in India. Further we are planing to manufacture ACTIVE ZINC OXIDE Please share your knowledge and technology for producing active Zinc Oxide. Anybody ready for consultancy may contact us .

Ravi Girase
Manufacturing white Seal Zinc Oxide - Daman Daman (UT) India
  ^- Privately contact this inquirer -^

How to convert zinc hydroxide to zinc oxide

October 16, 2017

Q. I want to know the which condition should I use to convert zinc hydroxide to zinc oxide and this zinc hydroxide was formed by precipitation of zinc chloride solution using NaOH.

riddhisiddhi parajiya
- rajkot, gujarat, india

October 20, 2017

Q. Can anyone tell me why all the zinc in the crucibles does not get vapourised/exhausted and some type of slag is found at the bottom while charging the metal. It is impossible to remove all of it and over time it builds up to 1 feet height at the bottom, and so the capacity of the crucible gets reduced.

Hari Prasad
- chennai, india

May 26, 2018

Q. I am interested in manufacturing Zinc Oxide (Ceramic Grade).

But for project physicality I need answer of few queries --
1. What are the possible raw materials of Zinc which can be utilized commercial for production of Zinc Oxide ?
2. Is zinc oxide can be manufactured from low zinc containing Zinc hydroxide ?
3. Manufacturing cost (excluding raw material cost) per MT production of Zinc Oxide (White seal) ?
4. Which fuel is good Diesel or Gas ?
5. What are the Government Clearances required for setting up of Zinc Oxide plant ?
6. What is Zinc Oxide annual Growth rate ?

I appreciate if anybody can give their recommendation on above query as much as possible.

Amit Patel
- Surat, Gujarat, India

June 2018

thumbs up sign Hi Amit. Best of luck! But your questions cover the whole gamut from marketing studies, to government regulations, to the practicalities of fuel selection, to the costs of production, to the feasibility of alternate & emerging technologies: I think you should strongly consider retaining a consultant because just a broad brush approach to these 6 topics would be at least a week's work :-)

IZA's "Zinc College 2018" in Finland ( is a 5-day introduction to several of your topics. Good luck.


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Striving to live Aloha

August 25, 2018

Q. Dear Participants,

We are a manufacturer of Zinc Oxide White seal in India. We planned to start manufacturing Zinc Hydroxide to further manufacture Zinc oxide from cancellation process.

We have the following Plant and machinery including reactors, filters, centrifuge, dryers.
We reacted Zinc Chloride liquid form with NaOH to form Zinc Hydroxide but the resulting formation is not drying.

Can anyone guide me through the process of its manufacturing?

Shubham Aggarwal
- Haryana, India

December 5, 2018

Mr. Shubham,
Normally zinc oxide from zinc hydroxide is manufactured by Sodium hydrosulphite manufacturers as they generate large quantity of zinc hydroxide.
When you reacted zinc chloride with NaOH, zinc hydroxide forms with NaCl salt, so you have to wash NaCl salt from the precipitate. After washing filtration of zinc hydroxide to get @ 30% - 40% wet cake. Usually this wet cake directly charged in rotary kiln for calcination to reduce carryover and loss of zinc hydroxide powder.
But you can first check the viability of the process you are planning to go with. As there are two roots, one is carbonate and second is hydroxide. In carbonate you can treat zinc chloride with sodium carbonate and make zinc carbonate. After calcination of zinc carbonate, you can get high surface area zinc oxide.

Umesh Charki
MetalliKon Consultancy Services - Thane, India

February 1, 2019

Q. We manufacture ZnO via the french process.

What is the typical particle size D[4,3] and D(0.5) expected for this process?

If hood design and available reactant (oxygen) is critical for particle size formation, what hood specifications should be adhered to for optimizing decreased particle size?

Any support is greatly appreciated.

Brad Volker
- Brisbane,Australia

March 13, 2019

A. Dear Mr. Brad,
We are more concerned about surface area than particle size analysis in India. We keep at @ 5-6 square meter/ gram, which is preferred by rubber industry. Higher surface area is preferred but it is costly.
To control particle size we need to understand the reaction kinetics and particle formation mechanism. It is Gas + Gas = Solid reaction. Actually burning of zinc vapours in air.
Also post reaction, solid particle formation is similar to crystallization. So if you want fines, rapid cooling is needed. But up to 450 °C, below there is no change in particle size. So you can design the hood for better dispersion/scattering of zinc oxide particles in air and two-stage air cooling to facilitate rapid cooling (fresh air inlet at upper part of hood).
The limitation of French process is surface area of 2 sq. mt/ gram to 10 gram. So for anything out of this range you need to check with alternative processes for zinc oxide manufacturing.
You can check with Dr. Shahrom Mahmud (Malaysia), He has done extensive work on zinc oxide particle fabrication.


Umesh Charki
- Vadodara, India

April 26, 2019

A. I fully agree with Umesh. He is absolutely right in controlling particle size vis a vis surface area. But I think Brad is requesting for control of secondary particle size... Something that you measure on a Malvern. This is important for a lot of pharmaceutical applications.

Brad, the solution lies in adjusting the hood to control secondary particle size to d50 less than 1 micron. Normally you get about 4.

Self Employed - VADODARA, Gujarat India

May 18, 2019

Q. Dear All,

It is a very warm feeling to be the part of this Group. We are the manufacturers of Zinc Oxide in North India by French Process.

Please help me out: how can we terminate turbidity of Zinc Oxide Solution in Phosphoric Acid. The turbidity even persists with the HG Grade also. Is it relating with particle size or something needs to be done with our Process to get turbidity free/Clear solution.

The solution consists with Phosphoric Acid, Nitric acid, water & Zinc Oxide.


Vikas Dass
Executive Sales & Marketing - Yamuna Nagar, India

May 27, 2019

A. Dear Mr. Vikas,
When you dissolve zinc oxide in phosphoric acid, Zinc oxide reacts with phosphoric acid and it’s soluble in water in all proportion. But free zinc in zinc oxide reacts with phosphoric acid to form zinc phosphate, which is insoluble in water. It produces turbidity in solution.
If you want a clear solution of zinc oxide in phosphoric acid, then you have to get rid of free zinc / unreacted zinc in zinc oxide. This is produced by complete burning of zinc in air and separation of heavy (unreacted) particles by using proper gravity settlers.

Umesh Charki
MetalliKon Consultancy Services - Thane, India

June 8, 2019

Q. Dear Charki Sir,

Thank you very much for your kind advice. I have some few more doubts to be clear.

1. we have a Batch Time of approx. 11 to 13 hrs with approx. 1700-1750 Kgs of RM (Bottom Dross) per Batch.
2. We have Gravity Settlers connected next to the Suction Hopper.

Kindly Advise:

1. Should we raise our Batch Time by slowing the Blower's Suction & hence provide more time for reaction/Burning of Zinc?.
2. The Height of Hoppers are approx. 13 to 14 inches from the Lid hole; please advice is it sufficient or need to be adjusted?

Shall seek your Expert Comments.


Vikas Dass [returning]
- Yamuna Nagar

June 11, 2019

A. Hi Vikas, I think I differ with you on some fundamentals.

Zinc Oxide is best made through semi continuous process and not batch process in a crucible furnace.

Blower speed is a secondary control for reducing rate of production, primary control is burner adjustment.

You have to control the ratio of primary air (that mainly goes through the bottom of your hood on the furnace) vis-a-vis quenching air (that enters from the gap between hood and the ducting). This can give you control over free zinc particles.

This information is quite fundamental to making Zinc Oxide. Anything beyond may not be possible.

I would suggest that you appoint a consultant. I do not know if someone like Umesh would be interested.

Self Employed - VADODARA Gujarat India

June 20, 2019

thumbs up sign Dear Abhay Sir,

Thank you very much for your special Comments.

We are working with conventional Oil Fired Twin Crucible method (French Process) for producing Zinc Oxide. A day normally produces 2 Batches (12-13 Hrs each) with charging of 1700-1750 Kgs of RM per batch. It is kind of semi continuous process.

The Burner adjustment is okay with us & is workable, Can you please elaborate the adjustments with Primary Air & Quenching Air.

We shall definitely be thinking about appointing a Consultant.


Vikas Dass
- Yamuna Nagar

July 2, 2019

Q. I have plant for production of zinc oxide by French method but i have a problem related with accumulation of zinc oxide over the molten zinc which need to be skimmed. I don't know what are the reasons of this accumulation? may be due to fallen of zinc oxide from suction inside the crucible or may be due to oxidation of the outer surface of molten zinc.
What is the remedy of this problem?

Mohamed El-Sadek
- Cairo, Egypt

July 4, 2019

Dear sir,
Can me suggest you that what have should be speed form rpm of suction blower with connected 20 HP 3-phase motor which has 1400rpm and its suction only from one furnace?

Bhavin patel
- morbi, gujarat, india

July 20, 2019

Q. Dear Experts;
We are beginners in zinc oxide production by French method and we have several problems with our burn oil furnace like escape of black fumes that have negative effect on the quality of zinc oxide product, crucible lifetime, low yield and high fuel consumption.
Because of these problems, we are thinking to replace the oil furnace with electric or induction furnace. I want to know your opinions about using electric or induction furnace instead of burn oil furnace.

- Cairo, Egypt

October 8, 2019

A. Suddenly some drought on this thread. I will try some technical tips...

Many ZnO manufacturers in India still use primitive open bag houses located on discharge side of the fan. But a few have gone ahead with reverse pulse-jet type and that is certainly a better solution. I will restrict myself to such bag filters.

Here the entry to the filter should have a one or two degree downward slope to direct the flow to the bottom.

The inlet must extend inside the filter but it should only be half-round inside, only the top portion, open at the bottom.

The inlet and outlet should preferably be oriented at 180 degree.

There should preferably an air receiver near the filter with capacity 1.5 litres per LPM of expected consumption. This will reduce loading unloading of compressor. There is no need to dry the air unless you are located very close to the sea shore and fear corrosion.

Self Employed - Vadodara, Gujarat India

October 12, 2019

Q. Will there be any benefit of having fins (Extended Surfaces) on the cooling duct after furnace up to bag house?
Lesser the length, lower the static pressure required by the ID Fan & hence lesser the power consumption.


Dinesh Mistry
Engineering - Vadodara, Gujarat

October 15, 2019

A. You are spot on. Fins will help. There are other methods too.

Self Employed - VADODARA Gujarat India

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