Trc. Patrick et Rr. Lovel, Leaching dicalcium silicates from iron ore sinter to remove phosphorus andother contaminants, ISIJ INT, 41(2), 2001, pp. 128-135
Although dicalcium silicates can constitute up to 10vol % of many modern he
matite/goethite iron ore sinters, traditional mineralogical investigations
of such sinters have largely overlooked this phase and focused on the more
abundant iron oxides and ferrites. However, dicalcium silicates have a rang
e of properties that make them unique in sinter parageneses. These properti
es may contribute significantly to hulk sinter properties and also make dic
alcium silicates potentially exploitable in novel upgrading processes. Anal
yses on a pot grate test sinter have shown that phosphorous land possibly o
ther elements including potassium and chromium) was heavily concentrated in
the dicalcium silicates. A series of etch tests have demonstrated that dic
alcium silicates can be selectively removed from the surface of polished si
nter samples using weak acids. In addition, bulk leaching trials showed tha
t the phase can also be removed from powdered and coarser (-5 mm) sinter in
mild acids. These leaches resulted in a >90 % reduction in phosphorous wit
h a 7 % improvement in iron grade for the powdered material and a 70 % redu
ction in phosphorous with a 5 % improvement In Iron grade for the coarser m
aterial. Two novel processes are proposed to exploit the leachability of co
ntaminated dicalcium silicates from sinter: one being a potential route to
a high-grade iron product, the other being a return fines washing circuit.