Application of Wood Char in Processing Oolitic High-phosphorus Hematite for Phosphorus Removal

Phosphorus removal from oolitic high-phosphorus hematite using direct reduction followed by melting separation was investigated. At the direct reduction stage, highly volatile wood char was prepared by carbonizing jujube wood at 673 K for 2 h and was used as reducing agent. The results of the direct reduction tests show that at a temperature of 1373 K, a char mixing ratio of 0.8, and a reduction time of 10 — 25 min, the briquettes reached a metallization degree of 80% — 84% and a residual carbon content of 0.13 — 1.98 mass%. Phosphorus remained in the gangue as calcium phosphate after reduction. The results of the melting separation tests show that residual carbon in reduced briquette negatively affects the phosphorus content (w[p]) in hot metal. When the reduced briquettes obtained under the aforementioned conditions were used for melting separation, hot metal suitable for basic oxygen steelmaking (w[p]<0.4 mass%) could not be obtained from metallic briquettes with a residual carbon content more than 1.0 mass%. In contrast, it could be obtained from metallic briquettes with residual carbon content less than 0.35 mass% by mixing with 2%—4% Na2CO3.