Modern trends of technological advancement in iron ore processing

Abstract

The authors discuss evolution of technologies and procedures in iron ore processing. It is emphasized that an iron ore treatment approach is governed by the type and nature of dissemination of metallic and nonmetallic minerals. Iron ore is mostly processed using magnetic, magnetic–gravity or magnetic–flotation separation. High grade ore with the iron content of 60–63 % is utilized without dressing, immediately after crushing and size grading. Magnetic and flotation circuits are used in processing of the most rebellious and finely disseminated low-grade ore. The ore pretreatment technologies feature the trends of introduction of press–rollers, which reduces energy inputs by 10–30 % as compared with the semi autogenous grinding. The essential improvement of size grading efficiency is reached via inclusion of fine sifting in the grinding circuits. Due to persistently growing demand for high-quality concentrate, fine sifting is also included in the finishing processing of rough concentrates. One of the methods to produce ‘super concentrates’ is the reverse cation flotation of rough iron concentrates using collectors composed of mono-, di- and ether amines, as well as their mixtures, including alcohols. The need to dress ROM hematite ore and to after-treat magnetic separation tailings of magnetite ore initiated engineering, manufacturing and commercial-scale introduction of high-gradient and highduty magnetic separators based on permanent rare earth magnets with the field density to 1.7 T. These machines have much smaller weight and consume much less energy than the high-gradient separators based on electromagnets. The promising method for hematite ore treatment is the reverse cation flotation. The use of the described processes, technologies and equipment allows production of concentrates with the iron content higher than 70 % and the silicon content less than 2 % at the iron recovery more than 90 %.