High concrete walls, barbed wire, surveillance cameras, steel entrance gates: From the outside, the site in the commercial area of ​​Mendrisio in Ticino looks more like a prison than a company.

But behind the well-secured walls is not a prison, but a factory of Argor-Heraeus AG for processing gold.

Four of the five largest gold refineries in the world are based in Switzerland, three of them in the southern canton of Ticino.

Once notorious for their secrecy, they now allow the press a glimpse of their work.

John Knight

Correspondent for politics and economy in Switzerland.

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The transparency should create trust for a business that has a chronic reputation for being based on the exploitation of people and nature.

In gold mines in Africa and South America, the workers, often including children, still toil to this day, sometimes under precarious or even life-threatening conditions.

The chemicals commonly used in mining, such as mercury, arsenic and cyanide, damage workers' lungs and contaminate soil and water.

In the research for his book "Goldwashing", the Basel criminal lawyer and corruption hunter Mark Pieth dealt intensively with the dirty sides of the global gold business.

His finding is: "Only a small portion of the gold sold in the world is truly clean."

Robin Kolvenbach claims to contribute to this clean part.

The doctorate in chemistry heads Argor-Heraeus, which has been fully owned by the Hanau-based family group Heraeus since 2017 and can process up to 1,300 tons of gold per year.

The company provides this service on behalf of third parties (jewelry industry, watch manufacturers, banks);

the delivered precious metals do not belong to her.

Nevertheless, one pays strict attention to their origin: "It is in our own interest that the value chain is clean," asserts Kolvenbach.

It is increasingly important to buyers that the gold comes from sustainable sources.

“Customers and investors want to know where the gold comes from.

So we are doing everything humanly and technically possible to trace the gold.”

It looks like an iron foundry

At first glance, the somewhat outdated factory building in Mendrisio – which you can only enter with protective goggles and special shoes and when accompanied by a supervisor – doesn’t look like sophisticated technology at all.

The company looks like a medium-sized iron foundry, except that the pots from which the molten, glowing precious metal is poured into molds are just the size of a fist and not the height of a man.

The delivered semi-pure raw material, known as doré bars, is matt and porous.

Before it is refined into shiny gold with a purity of 99.99 percent, a sample is taken and subjected to a PCR test: This reveals the invisible DNA marker that the mine that supplies Argor-Heraeus sprayed on the raw material beforehand Has.

In this way, it can be clarified without a doubt whether the material supplied actually comes from that mine.

In addition, the employees of Argor-Heraeus also take a sample of the melted doré gold and analyze its content of gold, silver, copper and other metals.

Kolvenbach explains that the origin of the material can be determined precisely from the resulting image because the metal concentration differs from place to place.

If a certified mine operator secretly smuggles doré bars from questionable sources into his delivery and simply provides them with the artificial DNA code, he will be caught at this point at the latest.