Rockwell Automation and Royal Mint strike gold with new recycling process

Collaborating with Rockwell Automation and a Canadian chemicals firm has helped the UK’s oldest company, The Royal Mint, to design and build a gold-recovery plant that will recycle more than 4,000 tonnes of electronic waste a year – helping to reach its net-zero targets, create jobs, and promote a circular economy.

Making a Mint from recycling: Fast facts

In 2021 the UK generated about 490,000 tonnes of domestic e-waste, of which only 32,700 tonnes (6.5%) were recycled
The Royal Mint and Excir are using patented chemistry to recover more than 99% of gold and other materials from electronic waste
More than 95 tonnes of precious metals could be recycled from waste electricals annually, from this process
The plant is controlled using Rockwell Automation’s Plant PAX DCS
The new site will reduce the UK’s need to ship electronic waste abroad and ensure entire circuit boards are safely recycled

The Royal Mint, founded in 886AD, is building an advanced metal-recovery processing plant to process more than 4,000 tonnes of electronic and electrical waste, to recover gold, copper and other materials that can be used by the Mint in a circular manufacturing system.

Working with Rockwell Automation, the new plant will use a chemical extraction process to remove gold from e-waste such as printed circuit boards found in discarded mobile phones and laptops, for use by the Royal Mint’s commemorative coin and jewellery business and is the first mint in the world to extract metals using this technique. Every part of the e-waste will be reused, where even the plastic bi-product will be “de-brominated” – where hazardous bromide is removed – as an integral part of the Mint’s circular economy and related net-zero plans..

Due for completion in spring 2023, the new plant will showcase an alternate, innovative approach to managing the huge volumes of household e-waste produced every year.

E-waste, also known as WEEE – waste electronic and electrical equipment – is a serious global environmental problem. In 2019, the world produced 53.5 Mt of e-waste, equivalent to 7.3kg for every person, containing an estimated $57bn value in raw materials (The Global E-waste Monitor 20201). Recovery rates of these materials are low. In 2021, the UK generated about 490,000 tonnes of domestic e-waste, of which only 32,700 tonnes were sent to an approved, authorized treatment facility2. The Royal Mint’s new facility is expected to produce 500kg or more of pure gold per year, and create 50 new jobs in manufacturing, logistics and sales, where the Mint currently employs about 900 people at its 38-acre site in Llantrisant, Glamorgan.

Operations and engineering leaders at the Mint proposed a recycling facility in 2020 and different processes were examined. They found that Canadian company Excir had developed lab-level chemistry to extract molten gold from mixed materials that was recovered using precipitation.

“We worked with Excir to refine that chemical process, and then a scale-up project was designed in-house by the Royal Mint,” says Leighton John, Operations Director at the Royal Mint. “Then we engaged with our long-term collaborator Rockwell Automation and OEMs to commission the plant for us.”

The plant uses Rockwell Automation’s PlantPAx® DCS, or distributed control system, to monitor and control each part of the multi-phase process. PlantPAx forms a common automation platform that connects disparate pieces of equipment in the complex plant and controls them in one place, using an interface familiar to the Mint’s engineers, who have worked with Rockwell for more than 20 years.

The process

E-waste is collected and manually sorted to isolate the circuit boards and components. These are then prepared and mixed with a patented chemical formula to leach out the gold, producing a concentrated gold solution. Post-leach e-waste can be processed to recover other metals and plastic. Using precipitation, the gold can be recovered from the liquid, is filtered and dried to produce gold powder that is melted into ingots. The process recovers more than 99% of high-quality gold from the waste. “A lot of e-waste metal recovery is done through very high energy-intensive smelting processes, whereas our technology works at room temperature,” says Leighton John. “It's also very quick and is more selective than throwing full circuit boards into a smelting platform.”

Rockwell Automation is building the plant with the Mint, incorporating sensors and PLCs to allow control and monitoring by the PlantPAx DCS. Process technology is designed and delivered by Rockwell on a skid basis, i.e. modular and off-site. “This speeds up delivery because we can manufacture the skids and test them off-site,” says Rockwell Automation UK managing director Phil Hadfield. “It also brings the commissioning time down, helping with the project plan, and there are some OEM [equipment] packages such as scrubbers and large vessels that will be shipped to site, where Rockwell is responsible for the full integration during commissioning and handover.”

PlantPAx will smoothly integrate the gold extraction process with the balance of other plant and the discrete (local) controllers such as the scrubber and conveyor systems. “The system architecture enables different vendors to manufacture different parts of the plant and then very easily plug it all together and give one, plant-wide infrastructure control when it's up and running,” says Hadfield. “That eliminates disparate control systems that you often have in projects like this and provides optimization improvements, such as common log-ons, change management, alarm management, data logging and more, visible across the entire plant, and this helps reduce the total cost of ownership.”

A modular solution built offsite, on a skid, reduces carbon impact in the installation, says Hadfield, and the DCS connects with the Mint’s energy management system to monitor and control energy consumption. The “one vision” system also makes spares ordering and maintenance simpler for supporting the plant moving forward.

A sustainable business invested in net zero

Alongside key drivers such as circular manufacturing and sustained employment, the metal-recovery plant is an important part of the Royal Mint’s net-zero roadmap.

“Our science-based targets were formally submitted to the Science Based Target initiative for validation, commencing on 5 June 2023. We have also started to implement our Net Zero roadmap, as we strive to deliver on our decarbonization ambitions across Scope 1 and 2 emissions sources, and Scope 3, from a baseline year of 2021/22,” says John.

In terms of Scope 1 and 2, the Mint has for example, an onsite wind turbine that offsets grid electricity, and it is in the process of bringing a local energy centre online in the coming weeks. This includes a second wind turbine and 4,000 solar panels, plus local electricity generation through a gas generator. “A local generator means there are no losses between power station and the site, too, which is great for an energy-intensive operation like us,” John says. Being able to recover gold and other precious metals on site will also help reduce the Scope 3 emissions of the Mint – an area that is often more difficult for organisations to decarbonize.

While the Mint is government-owned, it receives no subsidy and must operate as a viable business. Even though it exports coins and “blanks” (bald coin units with no markings) to about 60 countries a year, as the use of cash declines the Mint must diversify. When the recovery plant is proven-out, it could be expanded as a new business. “Once proven, all options are available; whether we expand it here, elsewhere in the UK or take the process abroad,” says John. “We want this plant to make a real difference to the mountains of e-waste being produced and the valuable metals being wasted.”

The new recovery plant is expected to be fully operational by early to mid-2023.