What is Spent pot liner?
Spent Pot lining (SPL) is a hazardous waste generated by the primary aluminium smelting industry. Spent Pot lining is also known as Spent Potline and Spent Cell Liner.
Primary aluminum production is the process of recovering the 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.
Why is Spent pot line hazardous?
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:
Because of this SPL is subject to the Basel Convention on the control of trans-boundary movements of hazardous wastes & their disposal
Land fill is banned in most countries because of the risks of dissolved fluorides and cyanides from the SPL leaching into the environment plus there is the risk of the toxic and explosive gas evolving if the SPL gets wet.
SPL is becoming one of the aluminium industry's most pressing environmental concerns. Most SPL is currently stored at the aluminium smelter sites or placed in special secured landfills. Both of these options are expensive and potentially only storing problems for future generations.
What are the options for spent pot liner disposal?
There are few good options for spent pot liner disposal. Moving the material 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 Ultromex technology removes by 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 feedstock in other industries.
If your company has a spent pot lining disposal problem talk to us today.