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Cutting up solidified zinc in galvanizing tank

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A discussion started in 2006 and continuing through 2017 . . .


Q. We have an emergency tank 1250 mm (W) X 1250 mm (H )X 5000 mm (L).
While evacuating pot kettle, about 20 tons of molten zinc filled the emergency tank.
The height of zinc in the tank varies from 150 to 300 mm so pump can't move it from the tank. Now, the Zinc is in solid state in the tank and we can't remove the tank with zinc because the crane is only 16 tons and total weight is about 31 tons.
We need a method to cut zinc up into small weights so we can remove it from the tank and use it again.

Ahmed Milad
coating - 10th of Ramadan, Egypt


A. Sir:
Many things have been tried to cut up zinc. Zinc "work hardens" rapidly which means a saw doesn't work. Most torches are not hot enough. Once I heard of a torch, I think "plasma arc" or hydrogen torch. I am having difficulty remembering, but it cost $10,000/hour for its use. I believe it did work. In Texas a large block of zinc was drilled and exploded with explosives. The factories in the area all lost their windows. I am sorry that I cannot remember more. Perhaps the various galvanizers' associations could help you. Check the internet.

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota


A. Sir,

We have faced similar problem. First we hired 2 mobile cranes of required capacity, lifted the tank and put on a suitable trailer. Trailer was unloaded at required place using same cranes. After that tank was cut using gas cutter. Zinc was then cut manually using long chisels and hammers. One person hold the chisel using a tong and 3-4 persons then hit hammers one by one continuously. We cut the zinc in to the pieces of 500 kg approx. You better outsource the job to any outside contractor who has required skill.


Atul Mishra
Metals and Engg - Murbad, Maharashtra, India


A. Sir:
The worker using the gas cutter needs a clean air supply pumped directly to his face to avoid the serious medical problem of zinc metal fume fever which can be deadly.

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota


Q. 300 ton of zinc. I have this block of zinc to get from kettle.

Willliam Ball
ael - UK

February 12, 2010

A. A practical method is to build a temporary cover over the kettle with gas burners attached to the cover. heat the interior of the kettle until the zinc melts. Use a smaller zinc pump that can reduce the molten zinc level to less than 75 mm. Manually scoop up the balance of the zinc while it is still molten.
If there is 300 tons of frozen zinc in the kettle, the same method still works.

Voo Yeok Kwee
- Shah Alam, Selangor, Malaysia

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

Q. I am having a HDG plant & my kettle has leaked due to crack in welding forming one big piece of zinc of approximate 10 feet by 12 feet & thickness varying from 1 inches to 4 inches. Can anyone suggest to how to cut the zinc in small pieces so that I can put in my zinc kettle.

Arvinder Singh
- Kanpur, U.P. India

April 27, 2012

A. If you have access to the edge of the piece, (say a large plate of zinc on a floor) you can lever it up off the floor, then break it with large hammers.
Its quite brittle when cold, and can be broken into chunks, but you need leverage, i.e., hitting a suspended plate in the middle.
Sharp hits break it.

If no access, you need to make some. A thermic lance does this, (but as above take fume precautions). You can easily cut a line in the plate. There's a high risk of cutting anything underneath too, steel, concrete or whatever.
A thermic lance is a steel tube, perhaps 20-25 mm diameter, packed with steel wires in parallel, inside the tube. One end threaded to take an oxygen feed from a hose.
Light the end with a gas torch, while allowing small oxy feed. Increase or decrease O2 as required. These will burn anything!
Do as few cuts as required to arrange a access to an edge, then swap to jackhammer or sledge hammer and start breaking it up. Crowbars can lever a plate off a kettle floor if you get an edge.

Geoff Crowley
Geoff Crowley
galvanizing & powder coating shop
Glasgow, Scotland

May 3, 2012


Ilesh G Vyas
Gunatit Builders

Manjalpur, Vadodara, Gujarat

First of two simultaneous responses -- May 4, 2012

A. Removing a full cold kettle full of zinc would be a very difficult job.

Geoff Crowley
Geoff Crowley
galvanizing & powder coating shop
Glasgow, Scotland

Second of two simultaneous responses -- May 7, 2012

A. Dear Mr. Crowley, thanks a lot for your reply but I have tried a wood circular cutter & it is working efficiently. The only problem now I am facing is that the teeth of the cutter diminish very fast ... maybe the quality of the cutter is not good or something else. However if any portion of the slab is left uncut then sledge hammer is enough to break the piece. Thanks a lot once again for all who responded to my query.

Arvinder Singh
- Kanpur, U.P. India

May 13, 2012

A. Yes, it's difficult but easy, then cut it by help of chisel or any cutter.

If you don't lift it out, create a furnace in position only with coal and remove the zinc; it will be easier.

Ilesh G Vyas
Gunatit Builders
Manjalpur, Vadodara, Gujarat

November 15, 2012

Q. I have a 8 M x 1 m x 1.4 M kettle made out of 50 mm DSQ plates. My plant has been shut down for 3 months, hence the zinc has solidified at 714 mm (i.e., about half a kettle) with dross about 200 mm.
I need to restart firing of the kettle. What I need to know is whether I should put more zinc in kettle or start firing as it is. Will the kettle take sufficient heat to liquify the zinc and will the kettle remain stable?

Owais Nuri
- Mumbai, Maharashtra, India

First of two simultaneous responses -- November 16, 2012

A. There's not enough info to answer this question.
Gas fired? Oil? Coal?

How deep the furnace?

Do you want to save the kettle, the zinc or both? If you loose (damage) one, which one preferred?

What are you trying to do? Restart (for production) a plant that's been shut down?

Geoff Crowley
Geoff Crowley
galvanizing & powder coating shop
Glasgow, Scotland

Second of two simultaneous responses -- November 19, 2012

A. You can add new zinc and restart the furnace with slow firing. At least 48 hours are required to melt the zinc with slow firing.

Ilesh G Vyas
Gunatit Builders
Manjalpur, Vadodara, Gujarat

January 15, 2013

A. Dear Mr. Ahmed, Mr. Arvinder,

Cutting Big Zinc Block
For cut big zinc block, you may use temporary movable small heating chamber and a burner.
Small heating chamber is only steel plate cover box.
Steel plate thickness is about 3mm.
Chamber box size is about Length = 700mm x Height = 600mm x Width = 450mm.
Two length sides & top side are closed and bottom is opened.
One width side (back side) is also closed and at another width side (front side), there is a door, (door size is about height = 300mm x width = 150mm) at middle & lower place of side area for fired by burner.
There must be a short chimney (about 100mm diameter) at the top & end opposite side of burner side and must use glass wool at all areas of inner surface of chamber box for insulating heat conduction. That is a small movable heating chamber box.
Flexible long hoses must be used for gas or oil and combustion air pipes of burner.

Put the chamber at the place to cut on the surface of zinc block and fire continuously day & night by burner.
Don't touch flame with zinc.
At first, zinc block will absorb heat and it will take time for start melt zinc. It is depend on volume of zinc block.
When zinc start melt, you must take out molten zinc slowly by slowly by using steel spoon or steel hook.
After start melt, melting will be accelerate.
Chamber and burner must be moved as necessary.
Any way, it will take time for complete cutting by depend on size & volume of zinc block.
This is our experience to cut big zinc block.
But one thing is just different that your zinc block is in kettle.
So that, you have to use this way by shrewd for convenience in your actual situation.
Width & height of your emergency kettle is only 1250 mm
and thickness of your zinc block is about 300 mm max.
I hope you can use well by this way.

U Hla Shwe
Yangon, Myanmar.

Hot Dip Galvanizing Plant. - Yangon, Union of Myanmar

January 9, 2013

Q. During the shut down period an interruption in the gas supply resulted in the zinc in our 5 m x 4 m x 1.8 m CERAMIC zinc kettle solidifying.
We have started the long process of gradual heating to remelt the zinc in the kettle.
The question is: Can I expect any damage to the ceramic kettle and a chance of failure of the lining ??

Kevin Warren
- Johannesburg South Africa

October 26, 2013

Q. Hello,

I'm having problem with Zn melting. I put about 3,5 t of Zn in ingots, but speed of melting is too slow. I got about 0,32 g/l/h. Ingots are putted in boxes, and between every ingot is net. How can I force melting speed?

Petar Alfirevic
- Knin, Croatia

January 19, 2017

Q. My zinc kettle leaked, so we short down so wen can fix the situation. We able to get the kettle out with solidified zinc still inside, with the use of two cranes (80 tons each). Now we are having difficulty in breaking the zinc into smaller sizes so we can remove them from the kettle. Please are there any effective tool(s) or ways that can be used to break the zinc into smaller sizes?

Eze Uche
Galvanizing - Sagamu, Ogun State, Nigeria

January 24, 2017

Q. I have 15*1.6 m and 2.45 height kettle. The zinc height is about 0.3 m and I cut the kettle sides to remove the zinc and I was surprised when I tried to cut the zinc by oxyacetylene and now I haven't any method to cut the zinc and think to make holes by drilling one beside the other to form a line to cut the block into pieces. Please provide me with the correct method of your experiences.

mahmoud darwish
- helwan, cairo, egypt
  ^- Privately contact this inquirer -^

January 27, 2017

A. It sounds as if you are speaking about an old decommissioned kettle that you wish to get the residual zinc out of?
And you've said you've cut the sides off the kettle? So does that mean you are left with a lump of zinc on a kettle bottom with no sides?
At 300mm thick its much more difficult. Thinner slabs, say up to 100mm thick can be broken. Use wedges and jackhammers and try to bend the slab, and it breaks.
But at 300mm thick this won't work without massive forces involved.
If you can also remove the steel from the bottom. Perhaps you will have to turn the whole upside-down?
If can do that and remove all the steel so that you are left with a huge slab of zinc, then I think you will have to cut into it using a saw. The type that's used for concrete can cut into the zinc. It doesn't have to cut right through, but at least 50mm deep. Then try to exert force to crack the zinc at the cut marks. A slab laid on something that holds most of the weight opposite the cut mark will tend to crack the rest of the way from the cut.

Short of this, there's the very messy, fumy method of using a thermic lance. This is a steel tube of about 20mm diameter, packed with steel wires inside, and you feed oxygen in one end, light the other with a gas torch, and apply the burning end to the zinc. But beware, this will create huge fumes of airborne zinc oxide, so adequate breathing gear is required. (not just a mask, an air-fed helmet).

Geoff Crowley
Geoff Crowley
galvanizing & powder coating shop
Glasgow, Scotland

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