Obiettivo The aim of this research is to achieve the most comprehensive possible recovery of the constituents of oily sludges and their economic exploitation. In comparison to other processes proposed, this approach has the additional advantage of being able to sell the recycled oil at market prices.Tests showed that the extraction yield is the highest (approx. 90-95%) with dry sludges and goes down to approx. 65-75% for sludge containing 65% of Total Suspended Solids (TSS), i.e. a pulp similar to the thickened sludge available at the ILP Tranto plant.Extraction yield was 50% with sludge containing 20% TSS, i.e. the one arising from clarifiers.Following these results it was decided to feed the pilot plant with a 65% TSS pulp that provides a fairly good extraction yield, is easy to handle and fouls equipment to an acceptable degree.Filtering tests showed that sludge has a good filtering behaviour either in vacuum or under pressure. Filtering behaviour improves when a polyelectrolyte (1.5 mg/g TSS) is added to the sludge.The oil extraction tests on the pilot plant have put in evidence an oil extraction efficiency variable between 58 and 62%.While performing trials, the biggest difficulty was to handle sludge and cleaning equipment between one test and the following since sludge would stick to the bottle and pipe walls.Concerning the economic profitability of oil recovery process, oil content decreased from 20% to 5-8% in the last year. Therefore it can only be used as a lubricant of rolling mills and not as a base for high-performance lubricants having a higher added value.The ILVA group, aware of the potential advantages of reusing oily sludges to recover the considerable quantities of raw materials and other valuable substances they contain for use within the steelworks production cycle, have accordingly instituted a research and experimental programme at the Taranto works.In its present form, the pilot plant has provided useful information about the economics of the process. This aspect is seriously compromised by the high cost of the emulsifying agent employed. This agent, specifically formulated for this application, nevertheless proved to be the only one of those assessed that was capable of meeting the requirements.So that the oily phase can also be exploited, it is proposed that this be extracted using solvents, with the oil subsequently being recovered by evaporation. Such an operation would make it possible to sell the oily fraction at the market price as recycled oil and to eliminate expenditure on the emulsifying agent (the key cost in the process as tested), thus rendering the plant profitable.The plant produces mineral iron, obtained from filter presses, and recycled oil separated out into the fractions saleable on the market. Programma(i) ECSC-WORKENV 5C - Fifth research programme (ECSC) "Technical control of nuisances and pollution at the place of work and in the environment of iron and steel works", 1985-1989 Argomento(i) 2 - Measures to combat fresh and sea water pollution Invito a presentare proposte Data not available Meccanismo di finanziamento Data not available Coordinatore CENTRO SVILUPPO MATERIALI SPA Contributo UE Nessun dato Indirizzo Via di Castel Romano 100/102 00100 ROMA Italia Mostra sulla mappa Costo totale Nessun dato
