Cutting up solidified zinc in galvanizing tank

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.
Regards,

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.

regards

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.
Regards,

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.

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.

A. FIRST OF ALL YOU HAVE TO TAKE OUT ZINC KETTLE FROM THE FURNACE, PLACE IT SOMEWHERE, THEN MAKE TEMPORARY COAL FIRED FURNACE AND PUMP OUT THE ZINC.

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

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.

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.

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?

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.

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.

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).

A. I have been reading about the need to cut large solid slabs of Zinc. We have had success in cutting Zinc into manageable pieces. It is not harmful to the environment or the person cutting because it does not cause the Zinc to get to a state where it can heat up or smoke. We have been hired to do this on many occasions and have success. Just letting people know that it is possible and feasible to cut Zinc safely.