No abstract

One of the most important problems encountered in minimill steelplants throughout the world is the disposition Electric arc furnace (EAF) dust-coal composite of dusts produced from the EAF. In a typical EAF operation, pellets were heated from room temperature to 1423 approximately 1-2% of the charge is converted to dust, and 1468 K under flowing argon by means of two which is collected in the baghouse. 4 -6 Dusts generated during heating patterns (non-isothermal tests). Apparent carbon steelmaking tend to be richer in zinc and lead, volume variation, compressive strength after while EAF dusts from stainless steelmaking are relatively heating, and zinc removal efficiency were low in zinc and lead, but richer in alloying elements such evaluated, the last as a function of the additives as chromium and nickel. 7 used in the present work. A decrease of pellet size Electric arc furnace dust has been classi ed by various (from 14 to 7 mm in diameter) as well as the government regulatory agencies as hazardous waste, because presence of Portland cement contributed towards of the leachability of heavy metals such as lead, cadmium, avoiding abnormal swelling caused by growth of and chromium. 8 This classi cation means that dust cannot iron whiskers, and, as a consequence, there was no be disposed of in an ordinary land ll site. significant decrease of compressive strength atThere are many diVerent EAF dust treatment processes ~1323 K. At 1397 K, highest zinc removal was used in commercial operations or at a developmental stage. obtained for pellets with 12 wt-%KCl, and reasonsThese can be categorised into the following: 9 , 1 0 (a) high for this result are proposed. I&S/1571 temperature metal recovery (HTMR) processes; ( b) hydrometallurgical processes; and (c) vitri cation or chemical Dr. Mantovani

No abstract

This paper presents a cybernetic structured mathematical model developed for the fermentation step of the process of production of the copolymer of polyhydroxyalkanoates by the bacteria Alcaligenes eutrophus. This process is performed in two different fermentation stages. The first emphasizes the growth of the microorganism in a batch operation without substrates limitations, while in the second, the focus is on copolymer production by a fed-batch operation in the absence of the nitrogen source. This paper presents the results of the treatment of experimental data and of preliminary parameter estimation. The fitting of the proposed model to the experimental data of a standard experiment showed a good agreement

The basic knowledge of the physical and chemical properties of the electric arc furnace (EAF) and secondary dust (SD) obtained by the characterisation provides important information on the potential problems that could be encountered during the processing of such materials. EAF dust consists mainly of very fine spherical particles. The most common phases in the EAF dust are solid solution of iron spinels generally enclosed into a matrix of calcium-iron silicate glass. Leaching tests show that as the Zn/Fe ratio increases, there is an increase in the zinc extraction, whereas the iron extraction decreases as the Zn/Fe ratio increases. It was possible to produce a SD containing 55 . 8% zinc by means of charging EAF primary dust-coal composite pellets into an induction furnace. SD consists of very fine particles presenting a mean particle size of 0 . 26 mm. In addition, SD contains significant levels of iron, chloride and fluoride. The iron content in the SD was identified as being iron droplets ejected from the bath caused by high intensity gas generation during the smelting of the EAF primary dust-coal composite pellets.