Investigation into magnetic properties and processes of separation of Abakan magnetites

An analysis is performed for the magnetization, coercive force, and chemical composition of dressing products. The use of pulsed magnetic fields made it possible to increase the content of iron in concentrate and decrease simultaneously the iron losses.

The "Abakan Ore Management" Joint-Stock Company delivers primary magnetite concentrate to the West-Siberian Metallurgical Integrated Works, where the concentration plant is absent; therefore, a poor concentrate is used, and the production efficiency decreases at the initial stage. Abakan grinding-and-concentrating plant produces primary magnetite concentrate 0-8 mm in size with an average iron and sulfur content of 48 % and up to 2.5 %, respectively. By the two-stage dry separation scheme, the tails of two size classes 0-10 and 5-20 mm form. Currently, more than 18 mln t of tails with iron mass share of 13.7 % is accumulated in tailing dump.

The technological samples of original ore taken in Abakan plant were investigated; the ore contained 24.1 and 15.2% of total (Fe,) and magnetic (Fem) iron, 46.6 and 39.5% of concentrate, as

well as 10.9 and 2.2 % of tails, respectively, of 0-8 , 0-5 , and 0-3 mm size classes. We determined the mineral composition of the samples and the degree of opening of the main ore minerals. Magnetite with grain dimensions from 2.5x2.5 up to 91x125 ^m and nonmetalliferous minerals form close concretions containing numerous inclusions. This governs the losses of useful components and decreases the quality of concentrate. Each sample was sized into classes, the magnetic parameters (magnetization J, coercive force Hc) were measured, and chemical analysis was performed (Table 1).

The magnetic properties were studied on ballistic installation with the magnetic field intensity up to 160 kA/m. The values of the magnetization J presented in Table 1 were obtained at H -144 kA/m. It is obvious that in ore and tails, the content of iron (particularly Fem) increases with a decrease in size of the particles; in concentrate, the inverse relationship is observed. The particles with greater magnetite grains are extracted during separation; their magnetic susceptibility у is high. With reduction in the particle size (less than 60 - 70 m), X decreases. The magnetic field of separator does not make it possible to extract mineral to the concentrate, and magnetite enters the tails, which ensures the high iron content in fine fractions. <...>