The Minex process is a metals extraction technology that uses chloride gas to recover metals After around a decade of development and about US$10 million of investment, Scoria CEO Matthew Dorman hopes to have a full-scale operation up by then, despite having a few further hurdles to jump over.
The patented Minex process is a metals extraction technology that uses chloride gas to recover metals. It has been developed alongside SRK Consulting and in cooperation with research institute RPC in New Brunswick, Canada.
The chloride gas is used in a fluidised bed reactor to vaporise the metal contained within the slag and recover it through condensation. The final metals retrieval uses industrial techniques such as electrowinning, precipitation, and oxidation, among others, to produce a saleable metal concentrate.
“In general, refineries don’t extract 100% of minerals in the concentrate so there is significant value of metal in the slag. Historically, it’s been left on the balance sheet or considered a liability, because the technology has not been available, largely due to the cost to extract the metals,” Dorman told Mining Journal.
The company is currently on the brink of its final $5 million pre-production phase, including more test work, reports and final costing, which should take six months to ready Scoria for full construction financing.
The total capital required to build a 250,000 tonne per annum commercial plant is expected to be some $280 million, which Scoria hopes to fund through an initial public offering, funds from institutions or possibly even government grants.
Post-financing, the first plant could be built and in operation within 15-18 months, with revenue coming thereafter, Dorman said.
There should be a large market for the technology, with estimates of around 2 billion tonnes of slag globally and about 20 million tonnes being added every year.
Dorman points out that there are a number of economic and environmental benefits to the technology.
Environmentally, the process is a dry one, meaning there is no acid waste.
“In the number of the tests that have been done to date, the EPA (Environmental Protection Agency) tests have ruled that the waste product from the process is non-hazardous. It is effectively a ferrosillicate, it can be used in ferro-concrete for construction and for mixing asphalt for aggregates in road building. Effectively you have a zero-waste process,” he said.
The process is also a closed circuit, whereby sodium chloride is electrolysed in a chloralkali plant, which produces chlorine and sodium hydroxide. Salt will be dissolved to form brine and is then reacted to generate the chloride gas needed for the process. The sodium hydroxide byproduct can be used to neutralise any additional chloride produced, or sold on.
“Today when we’re moving more into the whole circular economics, where we’re trying to reprocess and recycle and reuse, this is opening up another field whereby … you’re substituting primary feed for secondary feed,” Dorman said. “It’s more like a [car] production line than a mining scenario with the fact that we know what the process will do”
Economically, it is cheaper than other recovery technologies, as chloride gas significantly reduces the melting points of the metal, meaning the cost of extraction is much lower.
The time to revenue generation is also quite short, with the slags on the surface and generally being homogeneous, meaning measuring and surveying is easy, as is determining the contained resource.
Once the material has been sampled, the amount of chloride gas required can be determined and the reactor can be adjusted to the correct melting point.
“It’s more like a [car] production line than a mining scenario, with the fact that we know what the process will do,” he said.
The processing sites can generally be installed or constructed in brownfield areas, reducing permitting issues and cutting a project’s timeline. It also helps that the equipment used in the plants are standard size, meaning nothing needs to be custom made.
Dorman said Scoria has the choice of building a central site for the process technology, with material shipped there, or possibly a joint venture or licensing arrangement at existing smelter or foundry operations. This would depend on the volume of the waste stockpile.
The first plant is likely to be in Canada, with discussions ongoing with the Belledune Port Authority.
Scoria has chosen this location due to good connections with the New Brunswick government through previous test work, the need for employment in the area and its access to maritime facilities, the St Lawrence waterway and the North American markets.
This plan could change, however, if a client shows interest and wants a plant built at their operations.
In addition to being used on slag, Scoria has the option of branching out with the Minex process.
Other applications include extracting metals from complex ores, processing aluminium into bauxite without acid waste, and reprocessing e-waste from electronics.
“That is three more lines we are potentially looking at. The idea is once we’ve got this one moving down the line, we will have a pipeline of other service offers that can be available to the industry,” Dorman said.