Eco-Innovation - Ihobe

OPTIMISATION OF THE PRODUCTION OF HIGH PURITY Zn COMPOUNDS FROM WASTE

Zinc oxide is the main inorganic chemical in the zinc family and approximately 8% of the world's zinc is used annually to produce it, amounting to 1,000,000 tonnes. It is produced mainly by pyrometallurgical methods (in furnaces that evaporate the zinc ingots) or by hydrometallurgical methods, using non-renewable resources as raw materials, mainly from mines located in South America and Australia. In addition to the impact and consumption of natural resources involved, they are electro-intensive methods that require an electrolysis stage to deoxidise the mineral and produce the metal, and a subsequent oxidation of that metal. This inefficient production route is due to processes designed simply for the production of the metal, which is the main market for zinc (60% zinc metal vs 8% zinc oxide).

According to data from the European Green Deal, global annual extraction of materials tripled between 1970 and 2017 and continues to grow. Approximately half of total greenhouse gas (GHG) emissions and more than 90% of biodiversity loss and water stress are due to resource extraction and the processing of materials, fuels and food. Only 12% of the materials used by industry come from recycling. Energy-intensive industries are vital to the EU economy as they supply several key value chains. It is crucial to decarbonise and modernise this sector. The Basque Waste Prevention and Management Plan 2030 is committed to better management of metal waste as it reduces dependence on imports of these metals in the Basque Country, producing significant savings in the purchase of raw materials, employment and added value in their recycling.

COLLABORATORS

VALZINC is a project led by BOSTLAN, and addresses the production of commercial zinc compounds from different waste containing this metal by means of a process that avoids the generation of brine. The waste to be treated includes foundry ashes, galvanising sludge and mattes, brass foundry fines, and other possible compatible waste, all of which is generated in the Basque Country, in some cases in significant volumes. The new process allows the production of zinc carbonate and zinc oxide with sufficient quality and chemical purity to access the rubber or ceramics markets, with high chemical specifications and high added value.

VALZINC involves the construction and commissioning of a pilot plant to test batches of 100 kg of waste under semi-industrial conditions for the production of zinc oxide. The pilot plant defines the process applicable to each type of waste to be treated in detail and enables the necessary data to be obtained for an industrial plant. In addition, the project has designed and initiated a project market plan to ensure the stockpiling of Zn waste and initiate approval processes for the zinc oxide products to be obtained.

IHOBE has supported the design of VALZINC by helping to resolve critical aspects, such as the potential sustainable management of the brine generated, which is acceptable to the administration, and the location of feasible industrial sites for the implementation of the project. It also provided support in the business plan and the sourcing of secondary materials and product destinations. VALZINC has led to the search for funding for the industrial implementation of the process, as well as new development initiatives for the recovery of zinc from other waste sources.