低品位鉄鉱石の高勾配磁気分離に関する研究
1985 年 101 巻 1171 号 p. 525-530
詳細
1985 年 101 巻 1171 号 p. 525-530
The continual depletion of the world's iron ore resources necessitates the treatment of increasingly lower grade and finer size ores. In this paper high gradient magnetic separation was discussed as one of the beneficiation methods of iron ores. At first the capture of each single sample and the separation of the artificial mixture of hematite and quartz were investigated by using a high gradient magnetic separator (SALA HGMS). Next a low grade iron ore from Tou-Anzan, China was treated with HGMS on the basis of the separation data for the artificial mixture. The results are as follows.
1) Hematite particles of -74+10μm could be captured at more than 95% weight recovery by using HGMS under the conditions of magnetic field intensity 3-5×106/4πA/m, slurry flow rate 300m/h and pulp density 10%.
2) Fine hematite-quartz artificial mixture of -10μm could be separated at 62% total iron grade and 92-94% weight recovery in the mags by using selective flocculation pretreatment and HGMS. To promote the selective flocculation of hematite particles, sodium silicate of 1kg/t and starch of 0.3-0.5kg/t were added to the artificial mixture slurry and the slurry was agitated sufficiently.
3) Each size fraction of the iron ore from Tou-Anzan, China was treated with selective flocculation pretreatment and HGMS, however the positive effect of selective flocculation was not detected for -10μm size fraction. Though selective flocculation treatment for -10μm increased the iron recovery from 78% to 83%, it decreased the iron grade from 54% to 44%. Magnetization measurements and separation tests of the Tou-Anzan ore by using leaching in acidic solution or heating proved that the existance of a small amount of ferromagnetics such as metallic iron or magnetite locked with gangue minerals decreased the iron grade in the mags. In high gradient magnetic separation it is considered very important to grind iron ores without mixing metallic iron particles in consideration of the difficulty of ferromagnetics removal with conventional magnetic separators. Also it is very important to investigate the movement of ferromagnetics as well as quartz and hematite in selective flocculation conditions.
