Fostering energy efficiency and GHG-emissions savings through the recuperation of residual gases in the aluminium recycling industry

Introduction

The LIFE HYDROGAS project aims to be the first one to implement an innovative solution that is capable of stabilizing the waste gas stream (Hydrogas) from the aluminium salt slag recycling process. This project focuses on cleaning the gas and separating flows in such a way as to obtain separate streams of H2 and CH4 of high purity, which are used as alternative fuels to natural gas.

Technology Overview

A novel membrane technology will be used to obtain a high purity H2 stream on one hand and a CH4-rich stream on the other hand. Given the complexity of the stream to be treated and burned, it is necessary to include a cleaning stage to remove certain compounds, such as:

• Siloxanes
• H2S
• VOCs

This cleaning process will be integrated into the separation process head. Various purification techniques available in the market will be utilized to reduce the impurities in the gas to permissible limits, allowing for subsequent separation and utilization.

Recovery and Stabilization

Furthermore, the NH3 present in the gas stream will be recovered for subsequent sale on the market. The physical fluctuations of the Hydrogas stream will be stabilized thanks to the implementation of damping technologies. These technologies will ensure a continuous feed flow, thereby solving operational issues encountered in previous industrial experiences.

Environmental Impact

The successful installation and operation of a waste gas stream treatment and valorisation plant for energy purposes will significantly reduce the environmental footprint of the salt slag recycling process. The anticipated benefits include:

1. A reduction of 36% in environmental footprint.
2. Decrease in energy consumption by 17.9 GWh/year.
3. Reduction of 3,619 tons of CO2eq/year.