Start-up aims to make the copper industry more environmentally friendly

Using a new chemical process, the start-up Still Bright aims to replace environmentally harmful copper smelting.

Demand for copper is rising rapidly, as is the environmental pollution caused by its dirty production processes. The founders of the start-up Still Bright claim to have found a better and cleaner method. The company uses water-based reactions, based on battery chemistry technology, to purify copper in a process that could be less harmful to the environment than conventional smelting. The hope is that this alternative will also help to reduce the growing strain on the copper supply chain, as reported in a recent article by the US magazine MIT Technology Review, published by the Massachusetts Institute of Technology. “We’re really focusing on tackling the looming copper supply crisis,” the magazine quotes Randy Allen, co-founder and CEO of Still Bright, as saying.
Copper is now a key component in everything from electrical wiring to cookware. Renewable energy and electric mobility – with their significant demand for copper in photovoltaic systems and electric vehicles – are driving even greater demand. According to MIT, global demand for copper is expected to rise by 40 per cent by 2040.
As demand rises, so too do the impacts of copper extraction – that is, the process of refining ore into pure metal – on the climate and the environment, as Technology Review reports. Furthermore, there are growing concerns about the geographical concentration of the copper supply chain. Copper is mined and smelted all over the world. In the past, many of these mines had their own smelting facilities to process the extracted ore primarily using pyrometallurgical methods. In pyrometallurgical smelting, copper is extracted from ore – or recycled scrap – through a multi-stage process in which the material is heated to its melting point. This process takes place in fuel-fired or induction furnaces, whereby the melt is treated, alloyed if necessary, and then cast into finished products. Today, the smelting industry has consolidated, with the result that many mines supply copper concentrates to smelters in Asia, particularly in China.
This is partly because smelting consumes a great deal of energy and chemicals and can produce sulphur-containing emissions that impair air quality. “They have simply shifted the environmental and social problems elsewhere,” says Simon Jowitt, a professor at the University of Nevada, Reno, and director of the Nevada Bureau of Mines and Geology. It is possible to remove pollutants from a smelter’s emissions, and smelters are much cleaner today than they used to be, says Jowitt. Overall, however, smelting centres are not exactly known for their environmental responsibility, writes author Casey Crownhart. Even countries such as the US, which have abundant copper reserves and active mines, largely ship copper concentrates containing up to around 30 per cent copper to China or other countries for smelting. There are currently only two operational ore smelters in the US.

Avoiding the pyrometallurgical process

Still Bright avoids the pyrometallurgical process used by smelters and instead employs a chemical approach partly inspired by vanadium flow battery technology.
In the start-up’s reactor, vanadium reacts with the copper compounds in copper concentrates. The copper metal remains solid, whilst many of the impurities remain in the liquid phase. The entire process takes between 30 and 90 minutes. The solid residue, which contains around 70 per cent copper following this reaction, can then be fed into another process established in the mining industry – known as solvent extraction and electrowinning – to produce copper with a purity of over 99 per cent. ##This is by no means the first attempt to process copper using a water-based chemical process. Today, for example, some copper ore is processed using acid, and Ceibo, a start-up based in Chile, is attempting to apply a variant of this process to the type of copper that is traditionally smelted. The difference here lies in the specific chemistry involved, particularly the decision to use vanadium.
Jon Vardner, one of the founders of Still Bright, was researching copper reactions and vanadium flow batteries when he came up with the idea of combining a copper extraction reaction with an electrical charging step in which the vanadium can be recycled. Once the vanadium has reacted with the copper, the liquid mixture can be fed into an electrolyser, which uses electricity to convert the vanadium back into a form that can react with copper once more. It is essentially the same process that vanadium-flow batteries use to recharge. Whilst other chemical processes for copper refining require high temperatures or extremely acidic conditions to dissolve the copper, drive the reaction forward rapidly and ensure that all the copper reacts, Still Bright’s process can be carried out at ambient temperatures.
One of the greatest advantages of this approach is the reduction in environmental pollution caused by copper refining. In traditional smelting, the target material is heated to over 1,200 °C, producing sulphurous gases that are released into the atmosphere. In the Still Bright process, however, hydrogen sulphide gas is produced as a by-product. Whilst this is still a toxic substance, it can be effectively captured and converted into useful by-products, according to Allen.
Another potential source of pollution is the sulphide minerals remaining after the refining process, which can form sulphuric acid on contact with air and water. This is also known as acid mine drainage and is common in mining waste. The Still Bright process also produces such acidic effluents. The company plans to monitor these carefully to ensure they do not enter the groundwater.
The company is currently testing its process in a laboratory in New Jersey and plans to build a pilot plant in Colorado with a capacity of around two tonnes of copper per year. The next step is to build a demonstration-scale reactor with an annual capacity of 500 tonnes, which is due to come on stream at a mine in 2027 or 2028, says Allen. Still Bright recently completed a seed funding round of $18.7 million to drive the scaling-up process.
How the scaling-up process goes will be a crucial test for the technology and will show whether the typically conservative mining industry will come on board, says Jowitt from UNR: “People want to see what happens on an industrial scale. And I think until that happens, people might be a bit hesitant to get on board.”
Source: MIT Technology Review