From Irish scrap silver to silver nitrate: how we refine metal into lab chemicals

What happens to scrap silver after we buy it

Most of what comes to us is sterling: canteens of cutlery, tea sets, trays, chains. Some is continental 800 or 835, some old coin silver at 900. Every piece is weighed and read by XRF before we price it, on camera for postal lots, and that reading follows the metal from then on.

Not everything gets melted. A piece with Dublin marks from the 1700s is worth more as it is, and we say so. A bent fork from a 1950s canteen has no second life as a fork; its value is the silver in it, and the job is to get that silver out.

Once paid for, a lot is sorted by grade. Knives are stripped first, because a silver-handled knife is a steel blade and a handle full of pitch with a thin skin of silver around it. Then each grade is melted down.

Refining it to 999

Sterling is 92.5 percent silver and 7.5 percent copper, and melting does not change that: a bar poured from sterling is still sterling. Refining takes the copper out, and we do it ourselves, in Dublin. The metal goes into solution and the silver comes back out of it as pure metal, leaving the copper behind: fine silver at 999 parts per thousand, melted and poured as grain or a bar and read by XRF again before it goes anywhere. The detail is in how silver refining works. The short version: a 2 kg sterling canteen holds 1,850 g of fine silver, and that figure, not the 2 kg, is what everything downstream is counted on.

Most of that fine silver goes back to the trade as casting grain and bars. Then there is the part I find most interesting.

Why some of it becomes silver nitrate

Silver nitrate is what you get when you dissolve silver in nitric acid and let the water go: colourless crystals that darken in the light. It is one of the oldest chemicals in the book and still one of the most used: the starting point for most other silver compounds, silver nanoparticles, Tollens' reagent, the titrations every chemistry student does, and plating baths.

Dissolve sterling in nitric acid and you get silver nitrate with copper nitrate through it: the solution turns blue and the copper follows the silver into the crystals. Dissolve 999 silver and you get the clean salt. The chemical can only be as pure as the metal that went into it, so we refine first and make the chemical second. Each batch is then assayed for trace metals and ships with a certificate of analysis for that lot.

That is the thinking behind Liffey Chemicals, our precious metal salts range: silver, gold, palladium and platinum compounds made in small batches in Dublin and priced off the live metal market, as our buy prices are. Silver nitrate (AgNO₃, CAS 7761-88-8) is the first of them, 99.9 percent on a metals basis, reagent grade, in packs from 25 g to a kilo. Gold goes the same road: scrap refined to 999.9, then dissolved in aqua regia for the gold chloride that colloidal gold and catalysis start from. Platinum and palladium follow the same rule: known metal in, assayed salt out.

Why traceable Irish-refined metal matters

Open a bottle of silver nitrate from a catalogue and you know the grade and the lot number, not where the silver started, who refined it or how many countries it crossed on the way. That is normal in the chemicals trade, and nobody thinks about it until an auditor asks.

We can do better because we stand at both ends. Every gram we refine was bought from a named person with ID checked, weighed and tested on camera and given a lot number, so a batch of silver nitrate traces back through the refining to the scrap it came from. For a lab that is three things it does not normally get: provenance on paper, a short supply chain inside the EU, and a maker who answers the phone.

There is a plainer reason too. Irish silver has been leaving the country as scrap for as long as anyone has been buying it, to be refined elsewhere and sold back with someone else's name on the label. The chemistry is not exotic, the equipment is not enormous and the metal is already here. We are not a large refinery and I do not pretend otherwise. We are a small one that knows exactly what it has, and I would rather an Irish canteen did its next job on a lab bench than vanished into someone else's supply chain.

If you have silver

Today's price per gram for sterling is on the silver page and the free insured pack is at sell by post. To get your own metal back as 999 grain or a bar, see silver refining. And if you run a lab and want to know where your silver nitrate came from, now you do.