Sun Metals Supplied Wet Zinc Ingot

Lang emailed........
We have an immediate & high level safety concern with regards to your May delivery of SHG Zinc ingot. To the best of my knowledge there has been no issue with your April deliveries.

There are hidden cavities within the rear face of the ingot slabs that are filled with water. This is causing explosions in the furnace when the ingot is being charged/loaded to the furnace as the cavities are being submersed under the surface of the molten Zinc. The trapped water rapidly turns to steam and the coefficient of expansion of water to steam creates an explosion which sends molten Zinc out of the furnace and onto our staff.

Our PPE is fully compliant with long sleeve, long pants, eye wear, full face shield. But this safety issue puts our staff at immediate risk of severe 3rd degree burns.

Unfortunately we have experienced this issue a number of times with SHG slab supplied by SMC over the years of supply. CAA have reported this to SMC at every event. I was absent from CAA for 7 years so I can’t speak for that period but I can personally speak for the first time this occurred as I had molten Zinc burn my face and eyes. I had safety glasses on at the time but no face shield. After this first instance (circa 2003-2007) we made face shields mandatory PPE when loading/charging ingot to the furnace. I am aware of at least 2 other occasions that we have reported this issue to SMC.

Previous investigations at SMC site have determined a faulty float that controls water level on the quenching bath under the ingot casting conveyor. This was the outcome from the first investigation carried out by Trevor Healy. I soon after visited SMC site and Trevor walked me through what had occurred whilst I was on site. I do not know details of other investigations. They may have been provided at time of investigation but I can’t personally recall.

The ingots containing cavities are not instantly recognisable by visual inspection but what does appear to be a consistent visual indicator is a very rough rear face (open face) of the ingot and appears to be a higher % of dross on rear face of ingot. There are also multiple raised blisters/bumps on the rear surface of the ingots. See attached photos of where the blisters have been impacted with a ball peen hammer to determine if any water present. A high % of these blister cavities contain water.

My understanding is that the Zinc ingot slab is made, stored and loaded to transport in a dry environment. There is a risk on CAA end of getting wet whilst unloading but it is stored in a dry environment. The risk of wetting at CAA is minimal and would be mostly to top 4 ingots and sides of lower levels. We generally wont unload in heavy rain but will unload if light showers. The trapped water in cavities is in all layers of the ingot bundle and would be fair to say that it has not found its way into these blister cavities through any light showers of rain whilst unloading at CAA.

Can you please escalate investigation immediately as to why this is happening as we need it to be rectified immediately. This is an unacceptable safety risk to CAA staff.

11JUN24: Staff member experienced a Zinc explosion, see photos of face shield and shirt. LS followed up with Gigi and Isabella from Sunmetals, as they have not formally acknowledged the initial communication on the 21st of May.
25JUN24: Toolbox Talk to discuss issue. LS stressed the importance of wearing Welding hood and full face shield while loading furnace.
27JUN24: Sun Metals investigation was inadequate, refer to email from Isabella Sawyer 20JUN24, LS response on 21JUN24. Sun Metals to investigate further. So far 3 ships have been delivered with this issue.
28AUG24: Sun Metals still not provided adequate explanation/solution. Most recent record of trapped water was 02AUG24. Leave open.
19AUG25: Still no adequate solution from Sun Metals. The incidence has reduced significantly, but we are still wary (esp the feet ingots). New staff have been made aware. We will leave this open, if it occurs again, LS to push harder w Sun Metals.

Verification –
Reported by –LS
Closed by –
Date closed –