A new technological approach to the granulation of slag melts of ferrous metallurgy: obtaining glassy fine-grained granules of improved quality

Abstract

The technological factors required to improve the operational properties of granulated metallurgical slags demanded in the building industry have been analyzed. In order to satisfy these factors, a new technology for hydro-vacuum granulation of slag melts (HVG) has been developed. It is shown that the main advantage of the proposed HVG process is the provision of forced high-speed vortex convection of water, with the effect of vertical suction, crushing, and degassing of the three-phase (water–slag granules–water vapor) heterogeneous medium formed during the overcooling and solidification of slag. It is proved that the high-speed volumetric disintegration and overcooling with the degassing effect sharply reduces a degree of aggressive gas/vapor impact on the being cooled particles of slag, which, in turn, leads to the reduction of the perforation degree of the granules. The obtained granules are distinguished by stable fractionation and improved, well-defined dense amorphous glassy structure, the water-holding capacity of which has reduced from 45–50% to 25–13%, the actual moisture content from 24–20% to 6–4%, while the hydraulic activity in terms of CaO-uptake increased from the conventional 320–360 mg/g to 610–650 mg/g. Pilot scale research demonstrated that the designed equipment for the HVG technology allows sustainable control of the quality of granules, and it has the potential for further development and implementation.

A novel method of hydro-vacuum dispersion of metallurgical melts: research and implementation

“…As a result of experimental studies, it was also found that the use of hydrovacuum dispersion method is also highly effective for dispersing slag melts and obtaining from them amorphous solidified (glassy) powdery raw materials with high hydraulic activity, suitable for the production of construction (Portland) cement [29]. In the case of hydrovacuum dispersion of slag, the rational weight ratio "slag: water" was 1:18.…”

“…As a rational solution to the above problem, we chose the way of improving the design of the pilot unit [22] and expanding the functional capabilities of the innovative method of hydrovacuum dispersion of alloys [23], specially developed by us earlier for the above purpose. The general arrangement of the new dispersion unit and its main process juncture is illustrated in Figure 1.…”

“…Figure 14.Morphology (1), EDS and XRD spectrograms (2) of granules obtained by hydro-vacuum granulation of gray cast iron slag[29].…”

Hydrated aluminum powder for direct alloying of steel and alloys - challenges of the future

“…The main factor limiting the application of direct alloying technology in the conditions of out-offurnace processing, steel and alloys, is the increase in the amount of slag in the ladle [16]. Consequently, there is a necessity to perform an additional operation of slag downloading from the ladle, which slightly complicates the implementation of the technology, but by putting into operation the innovative installation of hydro-vacuum vertical suction and slag granulation [17], developed by us, this problem can be solved with minimum energy costs and operating time. According to the noted study [16] higher performance can be achieved by applying direct alloying technology under oxidizing conditions in order to increase the residual manganese content in the metal before out-of-furnace treatment.…”

Technological line for production of activated powders by hydro-vacuum dispersion of liquid metals

“…inclusions. The slurry formed with water cools down instantly without generating vapor, smoke or specific noise [4,5].…”