Ca-ferritic Slag

Keywords Stillwater Mining Company, Ca-ferritic slag. Magnesia-chromite bricks. Rotary kiln. Corrosion resistance test. Refractories, RHl... 

Within a direct cooperation project between Stillwater Mining Company and RHl AG a practical testing with different refractory brands and Ca-ferritic slag has been conducted at the Technology Center Leoben. 

The slag represents a Ni,-Cu,- and sulphur- rich Ca-Fe-oxide slag (Ca-ferritic slag type). The main slag components include two different Ca-Fe-oxides (one of type C2F) and Ni-Mg-Fe-(Cr)-(Co)-oxide of type magnesia-ferrite (see Figure 1). 

Figure 1. Exemplary microstructural overview detail, (a) Reflected light microscopy. Granulated Ca-ferritic slag with Cu-(Fe)-Ni-(Pd)-sulphide inclusions (light phases), (b) Scanning electron microscope. Detail of slag granule. Ca-Fe-oxides (1 and 2). Ni-Mg-Fe-(Ca)-(Cr)-(Co)-oxide of type magnesia-ferrite (3).

In the rotary kiln, with 92mm in diameter, up to six different brick brands can be installed and tested simultaneously (see Figure 2). The furnace is heated using a propane-oxygen gas mixture. The first rotary kiln test with Ca-ferritic slag was carried out between 1500°-1550°C l The second rotary kiln test was performed at 1650°C. ... 

The interactions of different combinations of refractory materials with the Ca-ferritic slag have been deseribed thermochemically with regard to potential reaction products formed at the interfaee and the solubility of the refractory components in the slag. 

During this cooperative work with Stillwater Mining Company a variety of tests were conducted at RHTs research facilities, including a complete characterization of the Ca-ferritic processing slag and two rotary kiln tests at 1500°-1550° and 1650°C. 

The Ca-Fe-0 system is of central importance for steelmaking. During the reduction of iron oxides in the blast furnace the reactions with CaO (lime), one of the most important additives, is of particular interest. The resulting calcium ferrites are consequentially important slag forming phases. The second industrial field of application of the calcium ferrites is the cement production. 

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