Before you apply single-coat white enamel ('direct-on white enamelling'), you must prepare the surface with a nickel coating (nickel flash) to ensure a good enamel bond. You can normally achieve this by dipping the item to be enamelled into a hot solution of acidified nickel sulphate. Metallic nickel is often deposited by ion replacement but alternative processes are available.
After rinsing, the surface is passivated (made unreactive) in a hot alkaline solution. This neutralises the acid residues and prevents rusting.
What you must do
In the nickel sulphate baths, significant quantities of iron hydroxide are formed. It is filtered out of the bath on a continuous basis.
You must not make any discharge to surface water or groundwater without consulting your environmental regulator. If you discharge without an authorisation, permit or consent from your environmental regulator you could be prosecuted and fined or imprisoned.
You must not discharge trade effluent to a public sewer without trade effluent consent or a trade effluent agreement with your water and sewerage company or authority. If you discharge without a consent or agreement you could be prosecuted and fined or imprisoned.
You must comply with your duty of care responsibilities when dealing with waste.
Spent nickel sulphate solutions are acidic and you may need to deal with them as hazardous/special waste.
- Reduce your waste management charges by de-watering sludges.
- Install splash guards and drip trays around baths to contain leaks and spills.
- If there is a spill, mop it up rather than rinsing it down. This will reduce the volume of wastewater you produce.
- Allow sufficient drain times to reduce drag-out.