Project Case Study

To clean up spent pickle liquor from galvanizing plants (and steel mills).

To prepare steel for galvanizing, it needs to be ‘pickled’, immersed in hydrochloric acid to remove the corrosion; in addition if galvanizing is incomplete, the zinc coated steel is re-immersed in the acid to strip the zinc and re-initiate the process. The resultant pickle liquor contains used acid, zinc and iron (Fe3) – a toxic solution.

The normal process to clean up the spent pickle liquor is to neutralise the solution with sodium hydroxide or limestone – an expensive process both to neutralize the acid and to dispose of the waste. EPA requirements are tightening in terms of disposal of both solid and liquid residues leading to an important need to find an alternative.

ABR’s patented technology has demonstrated an effective method to remove metals from acids. ABR has extended its knowledge of acid recycling and metals removal from sulfuric acid to hydrochloric acid (the preferred acid for pickling steel) and has demonstrated with the preferred membrane technology, that metals can be removed at the cathode. A pilot plant was set up at a client’s site to demonstrate separation of iron and zinc using a variant of ABR’s core technology. The process was successful leading to a program to recover the acid as well as separate iron and zinc from the SPL. The process will treat up to 1 million litres of waste solution per annum with potential savings in reduced landfill costs of $200,000 and generation of by-product value of $300,000.

Lab View  Vat Leach Columns