Improving the quality of magnetite concentrates due to high-frequency demagnetization

Abstract

The paper presents theoretical substantiation of the feasibility of applying highfrequency demagnetization before separation to obtain iron ore concentrates with close to the theoretically possible quality. It was determined that the length of magnetite floccules under the influence of a constant magnetic field with an induction of 0.25 T reaches 0.3 mm, while the average particle size amounts to 0.015 mm. Under the action of the magnetic field with a decreasing strength amplitude at a frequency of 70 kHz, complete destruction of magnetite floccules into individual particles was achieved. A comparative analysis of the flocculation rate showed that with a decrease in the size of the magnetite particles, it is necessary to increase the frequency of the alternating magnetic field in order to prevent flocculation. Thus, the flocculation rate is directly related to the size of the magnetite particles. To achieve 95% of the theoretically possible quality of the concentrate, ten steps of high-frequency demagnetization with decreasing amplitude of magnetic field strength with a subsequent magnetic re-cleaning separation are required. In such a way, the intensity of the magnetic product purification increases 14 times due to the release of non-magnetic particles from the body of the floccules.