At this year’s MINExpo International, which took place last month in Las Vegas, in the US, global petrochemicals group Shell launched its ShellSol 2046NA solvents extraction diluent tailored for the North American market.
Shell global business development manager Monica Karamagi explains that diluents play a critical role in the extraction of copper, uranium, nickel, cobalt, zinc and other metals.
“During the solvents extraction process, ore is leached with sulphuric acid. The resultant solution [PLS], which is called the pregnant leach solution, is then mixed with the diluent, in which an extractant is dissolved. The diluent [causes] the extractant to bind selectively to the targeted metal, for example, copper. The PLS then dissolves the copper-extractant complex into the diluent and subsequently separates the organic layer from the water layer,” she explains.
Karamagi notes that diluents are manufactured using a variety of hydrocarbons, such as a variety of paraffin, cylcoparaffin and aromatic hydrocarbons; however, the composition of the ShellSol 2046 range has been tailored to significantly improve copper yields during the extraction process.
“The aromatic content is key to getting the best performance from mining kinetics, selectivity and the overall yield of the target metal being extracted,” she adds.
ShellSol 2046NA has a lower viscosity, compared with other diluents. The lower viscosity and improved aromatic content of the product assist extraction kinetics, thereby yielding low-phase disengagement times and improved copper selectivity.
Phase disengagement is a critical factor in determining the solvent extraction process in copper mining.
Karamagi points out that ShellSol 2046NA also has a high boiling point range of between 205 °C and 295 °C and is also tailored to yield a high flashpoint of 84 °C, which significantly improves safety during the overall process.
It also has a significantly lower evaporation rate, compared with other diluents, “as it has been tailored to a specific carbon range, making it less volatile”, resulting in less solvent loss, Shell North America mining business development lead Arlène Pouw adds.
Shehighlights that the company has been supplying its ShellSol 2046AR, which is manufactured at Shell’s CAPSA refinery, in Argentina, to the South American mining market for a number of years. The African market also has a similar mining diluent , ShellSol 2325, which is manufactured at the Sapref refinery, in Durban.
Sapref is jointly owned and operated by Shell SA Refining and BP Southern Africa.
Pouw explains that, because the different refineries receive different crude oil products, the composition of Shell’s diluent products cannot be identical, but are made to the same performance specifications.
“There is a strong match between the North American and Argentinian Shellsol 2046 diluents in composition and key properties and performance specifications.”
She further points out that the launch of ShellSol 2046NA for the North American market, despite its availability in other regions, was due to the lack of production facilities in North America. Further, supply to North America could not be supplemented from Shell’s other facilities, as they were unable to meet regional demand and demand from North America.
Karamagi highlights that, owing to supply constraints, Shell underwent a debottlenecking effort to produce ShellSol 2046 in North America. Subsequently, Shell started producing samples of ShellSol 2046NA last year at its Sarnia refinery, in Ontario, Canada, and is now starting to sell the product in the North American region.
Bulk samples have been produced at Sarnia, and Shell is now preparing for large-scale trials of the product at North American copper mines.
“We are very excited to start producing this solvent at our North American refinery and we are excited to supply copper mines in North and Central America,” concludes Karamagi.