ZERMEG II – Zero emission retrofitting method ... - Fabrik der Zukunft

7.4 Mosdorfer GmbHThe hot dip zincing company Mosdorfer produces components for electricity suppliers with30 employees. Mosdorfer is a renowned specialist in this sector. It has developed from aforgery to an innovative partner of companies in the energy, railway and telecommunicationssectors.In the hot dip zincing plant the following products are processed: components for high voltage and medium voltage energy suppliers insulators dampers and spirals for electrical installationsThe following baths are used in the zincing plant:1. degreasing at a pH of 8 to 9, and 60 °C with a mixture of anionic detergents, towhich a continuous filtration with a poly propylene filter medium is attached2. four pickling tanks for steel pickling only3. two static rinse tank4. dezincing tank5. flux tank6. drying furnace7. zinc tank8. quenching tankThey used to buy 150 tons of hydrochloric acid. From our calculations it could be concluded,that the acid consumption could be reduced by 50 %.The time to dump the acid in a pickling tank was determined by the contents in zinc, as thecompany had a client for the spent acid, who however demanded a low contents in zinc. Zinccould be found in significant amounts in all the pickling tanks, because the operators werenot careful when selecting a tank for dezincing defective parts and racks. So a clearseparation of pickling and dezincing became the main goal of the project.The main weak point was the analytics used to determine the concentration of iron and zincin the pickling baths. The operators used a grafical procedure on the basis of density and pHof the samples. This method was not suitable to differentiate between zinc and iron. Sophotometric methods were tested for their practical application in the company. They alsofailed, because of the mutual interference of zinc and iron, and of two- and trivalent ironions. A procedure to prepare the samples by extraction was developed in laboratory scale.Its implementation in daily practise however proved not feasible.Only analysis by atomic absorption yielded accurate and reliable results. However sendingdaily or weekly samples to an external laboratory means a big expense for a small company.23