engleski

Treatment of Electric Arc Furnace Dust Prior to Permanent Disposal

Electric arc furnace dust (EAFD), classified as hazardous waste is by-product of the manufacturing of steel from steel scrap material. In order to recommend appropriate treatment procedure prior to permanent disposal five composite samples of dust from three steelworks were characterized including chemical and composition as well as heavy metal content in three types of extracts (TCLP, SPLP and DIN 38414-S4). Zinc recovery was done by alkaline leaching with 10M NaOH for 2 hours at 950C with solid/liquid ratio 1:10. Leaching residues were further characterized for chemical composition and leaching properties. Maximum concentrations of zinc and lead determined in TCLP extracts of untreated EAFD were 204 mg/L and 42.2 mg/L respectively. After alkaline digestion of the dust in 10M NaOH solution concentrations of zinc was over 15 times lower and lead over 200 times lower compared to TCLP extracts of untreated EAFD. In DIN 38414-S4 extracts of either original or alkaline digested dust, only Cr (VI) exceeded permissible value. Removal of zinc by alkaline leaching ranging from 50.3 % to 73.2 %. Removal efficiency was highly dependent on the mineral composition of the dust especially on franklinite/zincite ratio.

heavy metal; leaching; waste treatment; pH; recovery

nije evidentirano