20 Oct 2023
We are glad to announce that one of the partner of the SisAl Pilot project, The National Technical University of Athens (NTUA) has just released a new article. The publication ‘Aluminium extraction from a calcium aluminate slag using sodium carbonate based on the critical examination of the patented industrial Pedersen process was published in October in the Journal Hydrometallurgy.
One of the main objectives of the SisAl process is the separation of CaO and the Al2O3 content of the calcium aluminate slag that is produced as a by-product in the main aluminothermic reduction step.
This separation is primarily achieved by leaching of the ground slag with a Na2CO3 solution. The process leads to the dissolution of Al2O3 into the solution and its separation from CaO. The latter precipitates as CaCO3. This process was originally applied in industrial scale in the 20th century in Norway and was called “The Pedersen Process”, from the name of its inventor. Although a plant operated for 40 years with this process, no engineering insights were ever presented in the literature about the critical parameters of its operation until now.
In this publication the Technologies for Sustainable Metallurgy Group (TeSMet) from NTUA recovered and presented for the first time in literature technical information about the metallurgical parameters governing the operation of the industrial Pedersen Process, with focus on the leaching stage. These parameters were critically analyzed by a physicochemical model proposed by the TeSMet Group that describes the leaching process. Based on the critical evaluation the team went on to devise an experimental plan to test (a) if the principles of the industrial Pedersen Process can be applied to slags produced by the SisAl process and (b) whether the leaching process can be further intensified and be performed with increased productivity (more slag leached per leaching cycle) compared to the original Pedersen Process. The results showed that SisAl Pilot slags are suitable to be treated with the optimized process proposed and increased productivity is indeed feasible.
More info about the article can be found here.