MFL can be generated during the dry-neutralization stage of smelting gases in the production of frits and enamels. The flue gases from smelting furnaces contain fluoride (hydrofluoric acid, HF) which interacts with lime particles. With former technology, it was not possible to generate a MFL by-product ready for reutilization. The purification line, in charge of processing the smelting gases, had two main constraints: first, the fluorine proportion was not regulated properly. Second, the purification line was also not able to capture all the dust in the smelting gases. As a result, the MFL composition was inhomogeneous and therefore not suitable for reuse. In this context, the implementation of damage-reducing techniques in the production process that allow generating homogeneous MFL is the key to minimize its environmental impact.
The project addressed these issues by applying a new technology, environmentally sustainable, which solves the problem of wasted MFL by-product and enables its usage as a valuable raw material. The project was coordinated and implemented by EMO-FRITE (Slovenia) and funded under CIP Eco-innovation. Final conclusions will be reached in September 2013.
The main parts of the frits production process were reorganized and improved: the inflow of gases, the filtrating step, the reactor for neutralization and the separating step. The key innovations were twofold: first, the redesign of the separation unit in order to allow capturing the dust present in the smelting gases. And second, the application of flue gas dry-neutralization in the process. This technique is based on the reaction between fluoride gases (arising during the melting of frits) and lime through the chemical reaction of neutralization to produce MFL. The key feature is that the feed rate of the micronized lime injected in the reactor varies depending on the HF concentration in flue gases. The application of both innovations ensures an optimal reaction rate and material consumption. And thus, the formation of homogenized MFL.
Thanks to a new implemented purification line, homogeneous MFL by-product has already been produced. When a certain amount of MFL is reached, the stock will be used in the production of new added-value enamel. Improvements are expected in the enamel quality such as lower thickness or less material use for obtaining equivalent product’s characteristics in the end. Further potential applications of the recycled MFL consist of frits and special ceramic products.
The enamel produced using the MFL by-product will be used as market electrostatic black powder and ground coat enamel for system 2C/1F wet/dry. This enamel is adequate for cookers and similar final products where corrosion is critical. Moreover, potential applications in white goods are conceivable. The project coordinator has already received several orders; business and commercialization plans are under implementation. In this context, the Technology Readiness Level is estimated at 9 in the TRL scale.