Introduction of silicon slag

1、 Production Silicon slags are the remains of the manufacture of silicon metal，the main content of which is Slicon (45%-95%). They are susually treated as waste.

2、 Useage Acturally they can be widely used in indusrtial processes, such as to be used as a good substitute for ferro silicon in steel making, which may considerably reduce production cost and resource waste. They can also be made into silicon ball and then to be used as deoxidizer and heat-riser in steel making and casting.

3、 Category As we all know, silicon slags are by-products made during silicon smelting. According the places where they are formed in the furnace, silicon slags may be sorted as :

(1) Scum (floating on the surface of melting silicon ) : 

Si :30-40% C :8-15% Fe:1.5-2.5%

(2) Normal Silicon slag (formed between scum and melting silicon):

Si:45-80% C:8%max Fe:1.5-2.5% Al:6%max Ca:5%max S:0.05%max P:0.04%max

(3) High-carbon Slicon (precipitated on the bottom of the furnace due to underreaction):

Si :65-72% C:18-24% Al:1%max, Ca: 2%max, Fe: 1.5%max, S: 0.05%max, 

P: 0.04%max

(4) Off-grade Silicon (adhered to the furnace liner or to the casting mould):

Si : 80-95% Fe :1.5%max Al :1.5%max Ca :1.5%max

Usually, Silicon Slags are crushed into blocks of designated sizes or be kneaded into balls just as the following pictures.

4、Trend With the improvement of metallurgical technology, silicon slagswill gradually reduce and eventually fade away. One of the most obvious examples is that High-carbon Silicon used to be cutted from the furnace bottom every two or three months to maintain the normal use of the furnace several years ago, but now the interval period is six months or a year. Furthermore, Silicon contained in the slags is also decreased as a result of technical progress.