PROJECT DESCRIPTION
BACKGROUND
Aluminium is a 100% recyclable material that retains its original properties. The recycling process is straightforward and resource efficient. Therefore, the aluminium recycling industry plays a vital role in the global effort to promote sustainability and addresses several critical needs.
The most significant aluminium recycling technique to recover aluminium from various scrap sources is based on the use of salt fluxes. This recycling process is characterised by the melting of scrap or slag aluminium waste in processes involving the addition of fluxing salts. The process produces a hazardous residue known as salt slag (code 100308). Such waste is a growing environmental concern because it is not easy to dispose of. The huge amount of salt slag produced make disposing of such a hazardous substance a worldwide problem.
Currently, the disposal of salt slag in landfills is banned in most European countries, so this waste must be properly treated to minimise environmental impacts. In Europe, there are more than 270 known aluminium-processing plants but only 10 salt-slag recycling facilities. They are located in Germany, France, Italy, Norway, the United Kingdom (UK) and Spain.
The company BEFESA operates a 5-stage recycling process for this waste that enables the recovery of the free metal and fluxing salts and the formation of inert products, composed mainly of aluminium oxide, as well as ammonium sulphate. In one of these stages a waste gas stream, applying hydrogas, is generated, which is burned in a gas flare, potentially emitting a host of air pollutants.
OBJECTIVES
The project’s main objective is to implement an innovative solution capable of stabilising the waste gas stream, cleaning it and dividing the flow into separate streams of hydrogen gas (H2) and methane (CH4) of high purity which will be used as alternative fuels to substitute natural gas in a steam boiler. The production of hydrogen as a clean fuel from waste is one way of creating a more environmentally friendly waste disposal system.
The specific objectives of the project are to:
- demonstrate, on an industrial scale, the membrane gas separation technology for hydrogen rich gas flow together with a gas cleaning stage
- analyse the hydrogas waste gas stream and generate sound knowledge to be applied in other salt slag recycling plants
- successfully test and validate the hydrogas demonstration plant to thoroughly assess every aspect of the plant's operation, from its individual components to its overall performance under various conditions
- achieve a reduction of greenhouse gas (GHG) emissions through the substitution of natural gas consumption by H2 and revalorised CH4
- facilitate relevant economic savings linked to the reduction of natural gas consumption in the aluminium recycling process. Additionally, a new source of income from the sale of ammonia (NH3) derivatives could be developed
- create sustainable and high-quality green employment opportunities over the long-term
- replicate the results of the LIFE HYDROGAS project in the other BEFESA salt slag recycling plants for a period of 5 years following the project's conclusion.
RESULTS
The project’s expected results are as follows:
- 3 618.59 tonnes of carbon dioxide (CO2) equivalent per year will be saved over the course of the project
- the Technology Readiness Level (TRL) of the membrane gas separation technology for hydrogen rich gas flow will increase from 6 to 9
- a potential saving of €771 342 per year thanks to the reduction of natural gas consumption. An additional €31 954 each year is expected to be earned from the sale of NH3 derivates
- the treatment of 5 724 normal cubic metres (Nm3) per year of hydrogas
- the recovery of 3 512 761.65 Nm3 per year of H2; 894 718.44 Nm3 per year of CH4; 5 769.8 tonnes per year of ammonia sulphate; and 2 519 tonnes per year of other ammonia derivates
- the generation of 17.9 gigawatt hours (GWh) of energy from products recovered from the waste stream.
