ALTEK has successfully installed a large capacity salt slag recycling plant, ALUSALT, as a demonstration unit, in Northern Europe at an aluminium recycling operation, where it is currently in the final stages of commissioning and optimisation, a press release from the company has confirmed. The plant has successfully taken salt slag, removed the salt, re-crystallised the salt for re-use, and generated oxides (NMP) that can be used in various markets. The company will commercialise the new technology in 2018.
Usually aluminium metal units are recovered from aluminium scrap and drosses using the rotary salt furnace (RSF) process, a process that produces salt slag as a bi-product. This is the easiest and most cost effective way to recycle scrap and aluminium dross. Typically, salt slag contains 5-20% of aluminium metal.
Salt Slag can no longer be landfilled in Europe and Middle East as it used to be and is currently in the USA (which may change in the future), and many countries/regions of the world do not use it because of the inability to easily dispose of it. Consequently all salt slags in Europe are sent to central processing plants for recycling.
These central processing units, of which there are only a few in Europe are extremely expensive to build, and operate, requiring a minimum 100,000 tpy capacity to make them economically viable.
Existing salt slag recycling technology recovers entrained aluminium by crushing and screening the cake, dissolving the soluble salts and recovering them by evaporation of the water, and then filtering to recover Non Metallic Particulate (NMP).
ALTEK with its ALUSALT™ technology has developed a lower CAPEX and OPEX alternative to this existing technology, making it possible for aluminium recyclers to recycle their own salt slag at site with significant economic and environmental benefits.
ALTEK started developing a “Mini Salt Recycling plant” in 2011 which is now called ALUSALT.
The objective was that this technology could be located at the place where the salt slag is initially generated, to allow an environmentally and economically efficient way to recycle the salt slag and give security of management of waste streams from their operations to the aluminium recycler.
All components of the salt slag can be recovered and re-used in the ALUSALT process. The products derived from the recycling process are all classified as non-hazardous. Effective recycling can reduce material sent to landfill to zero with significant environmental benefits for the landfill operators.
A high proportion of the European operations that generate salt slag are actively in discussions with ALTEK on this technology and many have already run trials through the pilot plant at ALTEK’s facility in the UK.
The ALUSALT technology will remove the significant cost for transportation and the associated CO2 emissions. It will also impact on space required for storage of hazardous material. Currently recyclers have to cool their salt slag to a temperature below 70°C before they can transport to the recycling plant.
It is estimated that the majority of European aluminium recyclers that generate salt slag, produce between 5,000T to 25,000T per year of salt slag at their site. ALTEK is in discussions with many of these operations during the course of the ALUSALT development project.
The modular design plants will range from 4000tpy to 30,000+ tpy in size and will cover all the current salt slag recycling requirements of the majority of aluminium recycling plants in Europe. The demonstration plant that has been built by ALTEK has been sized to accommodate the middle of this range.
The environmental and reduced CO2 benefits of recycling the salt slag at site fit well with the circular economy strategies being adopted throughout. The implementation of the new ALUSALT technology will be a paradigm shift in aluminium recycling. It will lower the barriers of entry to new and local scrap operations and allow regions to recycle salts.
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