Abstract
The secondary steel refining process uses filler sand as a thermal insulating barrier that separates the liquid metal from direct contact with slide-gate system of the steel ladle. The effective use of this practice must provide a high free opening rate, impacting on increased productivity and quality of steel, reducing the number of stops, thermal loss and even the steel re-oxidation. Both operational parameters and material properties have influence on the free opening rate. In the present work, two chromite-silica sands were analyzed, and some composition changes were proposed. The properties of these materials and the relevant process parameters were evaluated according to the free opening rate under normal operational conditions. The increases in carbon content and in particle size were considered the main factors relating to the filler sand. The percentage of free opening is also strongly influenced by time and temperature of the steel contact.
Highlights
In an electric steelmaking, there are great concerns about the operational variables that limit production in the continuous casting process
In order to avoid the contact between molten steel and the slide-gate system, a granular refractory material is used, called ‘filler sand’
The results of this work show that the free opening rate depends on the operational parameters tested in this work, such as contact time between molten steel and filler sand, process temperature and wt% C in the steel, and physical and chemical properties of the filler sand
Summary
There are great concerns about the operational variables that limit production in the continuous casting process. This process consists of passing the steel ladle from tapping to teaming, until the formation of the semi-finished product. One of the major factors that can delay the process is called ‘non-free opening’ of the slide-gate system that block the flow of steel from the teaming ladle to the tundish. In order to avoid the contact between molten steel and the slide-gate system, a granular refractory material is used, called ‘filler sand’. Different types of filler sands can be employed into the inner area of the nozzle and the well block. Several operational variables and materials characteristics affect their performance[1]
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