Introducing CARBOMEX : a new commercially attractive technology to safely recycle spent pot liner waste & dispose of the residues as valuable secondary resources
Spent pot lining is an extremely hazardous waste and has long been a problem waste stream for primary aluminium smelters.
Due to its hazards, landfill of SPL is banned in many countries. SPL contains toxic compounds including leachable fluorides and cyanides, plus it reacts with water; hydrolysing to produce explosive gas mixtures of hydrogen and methane.
If landfilled it can cause serious environmental damage and is a major threat to human health.
Transporting un-treated Spent Pot Liner is dangerous and expensive, being subject to the protocols of the Basel Convention on the Transboundary Movement of Hazardous Wastes and their Disposal.
Many producers have taken to storing their SPL, waiting for a cost effective treatment solution. Storage is expensive, brings risk of environmental damage in the event of unforseen events and is a ever increasing financial liability.
Ultromex has developed CARBOMEX - a low cost plant and process to treat and fully recycle spent pot liners so that they can be transported safely and disposed of permanently & sustainably.
Spent Pot lining (SPL) is a hazardous waste generated by the primary aluminium smelting industry. Spent Pot lining is sometimes referred to as Spent Cell Liner or Spent Potline.
Primary aluminum production is the process of recovering the useful metal form of aluminium from alumina (aluminum oxide). The most common manufacturing process is the Hall–Héroult process which involves electrolysis of the alumina in large electrolytic cells, referred to as ‘pots’.
The cells are constructed in layers contained within an outer shell made from steel. Inside is an inner carbon lining which acts as the cathode for the electrolytic cell. Between the carbon layer and the steel casing there is a refractory layer designed to keep heat in the cell.
During the electrolysis process, a number of substances including aluminium & fluorides are absorbed into the cell linings. After several years the pot lining will need to be replaced by removing the inner layers and re-lining with new carbon and refractory. The material removed is then known as ‘spent pot lining’ or (SPL). The SPL exhibits a number of properties which mean that it is considered to be ‘hazardous waste’ in many countries:
It contains toxic fluoride & cyanide compounds plus it has a high pH due to alkali metals & oxides making it corrosive.
Finally, it reacts with water producing flammable, toxic & explosive gases.
There are few good options for spent pot liner disposal. Even moving SPL around is dangerous and expensive. Secure landfill is very expensive and may be only delaying an environmental problem. Storage is not a sustainable solution.
The CARBOMEX technology from Ultromex removes the need for storing or land filling spent pot line by being the first commercially attractive process for the treatment of spent pot lining so that it is no longer hazardous and thus can be safely transported around the world for use a secondary recource and feedstock for other industries.