A round table discussion on slag at the 8th International Secondary Lead & Battery Recycling Conference is leading to the potential birth of a slag council.
A panel discussion at the conference in Siem Reap, Cambodia, and lively Q&A addressed the question of what slag is, where it comes from, and what can be done with it.
Opening the discussion, independent consultant Doug Lambert said 8 million tons of secondary lead production and slag is a challenge. “This round table…will lead us towards improving the secondary lead production process,” he said.
Sander Arnout, CEO of InsPyro in Belgium said typically, slag and matte comprise molten oxides and molten sulfides respectively. “It contains everything that we have in raw metals that’s not metal,” he said
Conference chair Mark Stevenson said it was important “to understand what kind of slag we want to make”. He added: “It goes back to the fundamentals of what you are putting in and what you are making.”
He called on the industry to come together and build a nomenclature and knowledge bank. He also demanded the industry be properly recognised as “a true metallurgical operation” and not a waste operation, as we reported last week.
Stevenson told the round table he saw no way of making money from slag, while Joe Grogan, chief technology officer at US-based Gopher Resource, said his company was working with different types of slag and commercially exploiting the product. Gopher Resource won the 2023 BCI Innovation Award for a process that cleans slag.
It has patented a process called SCRUM (Slag Cleaning and Recovery of Useful Metals). It separates the tin and lead as a concentrated fume.
Some projects create slag worth $20–100/ton, he said.
Separating out tin was “the big holy grail”, said Stevenson, adding it can be a nightmare.
Darren Nelson, director of Nexus Recycling, told the conference slag was always regarded as a cost centre, and determining otherwise would be a good research exercise.
Industry consultant Brian Wilson pointed out how hexagonal paving slabs had been made from slag, which he conceded was an intermediate solution to what to do with slag, but better than putting it in landfill.
Stevenson invited interest from the audience for a working group and received an enthusiastic response. It would consist inter alia of:
- a members’ forum
- database for papers
- projects and test work.
The working title is “the Slag Council”.
Photo: Round table discussion on slag. Left-right: Mark Stevenson, Darren Nelson, Brian Wilson, Doug Lambert. On screen (clockwise): Sander Arnout, Davi Trindade, Joe Grogan