Among the various factors affecting the magnetic separation process, the magnetic field strength, the rotational speed of the drum, the size of the flushing water, and the magnetic declination all directly affect the sorting index. However, as the laboratory equipment, the flushing water and the magnetic declination are fixed. Therefore, we only tested the magnetic field strength and the rotational speed of the drum. The magnetic separation test process is shown in Figure 1.

Figure 1 Magnetic separation process flow chart

**First, the determination of the magnetic field strength of a section**

The **pyrite** cinder (dry ore) is first sieved through a 100 mesh sieve, and the sieved product is ground for 5 minutes on a rod mill. The grinding concentration is C=70%, stirred for 5-8 minutes, and the rotation frequency of the drum is 16 rpm. Under the condition of min, the magnetic field strength of one magnetic separation is 1500 oersted respectively, the current intensity of two-stage magnetic separation is 2500 Oersted, and the current intensity of three-section magnetic separation is 3000 Oersted. The test results are shown in Table 1 below. Show.

Table 1 Magnetic field strength test of a magnetic separation

Magnetic field strength (Oe) | product name | Yield(%) | grade(%) | Recovery rate(%) | ||

Fe | S | Fe | S | |||

1500 | Concentrate I | 29.82 | 59.49 | 0.274 | 34.91 | 4.70 |

Concentrate II | 10.78 | 61.75 | 0.259 | 13.10 | 1.60 | |

Concentrate III | 5.83 | 59.98 | 0.321 | 6.88 | 1.08 | |

Tailings | 53.57 | 42.79 | 3.07 | 45.11 | 92.62 | |

total | 100 | 50.82 | 1.74 | 100 | 100 | |

2000 | Concentrate I | 32.78 | 61.02 | 0.252 | 39.36 | 4.75 |

Concentrate II | 6.95 | 61.41 | 0.203 | 8.39 | 0.81 | |

Concentrate III | 5.82 | 60.50 | 0.294 | 6.92 | 0.98 | |

Tailings | 54.45 | 42.31 | 2.80 | 45.33 | 93.46 | |

total | 100 | 50.82 | 1.74 | 100 | 100 | |

2500 | Concentrate I | 33.68 | 60.11 | 0.223 | 39.83 | 4.32 |

Concentrate II | 5.41 | 61.72 | 0.254 | 6.58 | 0.78 | |

Concentrate III | 5.69 | 59.67 | 0.263 | 6.68 | 0.86 | |

Tailings | 55.22 | 43.17 | 2.960 | 46.91 | 94.04 | |

total | 100 | 50.82 | 1.74 | 100 | 100 |

The results in Table 1 show that under the same conditions, the magnetic separation of a magnetic field with a magnetic separation of 2000 Oersted is better, and the Fe grade can reach 61.64%. If the three concentrates I, II and III are mixed, The cumulative yield is 45.55%, and the cumulative recovery rate is 54.67%. The content of S can be reduced to about 0.3%. Since the yield of the three-stage magnetic separation is low, three-stage magnetic separation will not be performed in the following flow.

**Determination of the magnetic field strength of the second and second sections**

Sulfur **iron** ore slag (dry ore) first sieved through a 100 mesh sieve, the sieve product in a rod mill grinding ore 5min, grinding concentration C = 70%, was stirred for 5 ~ 8min, the drum rotation frequency of 16 rpm / Under the condition of min, the magnetic field strength of one magnetic separation is 2000 Oersted, and the magnetic field strength of the second magnetic separation is 2500 ohms and 3000 ohms respectively. The test results are shown in Table 2.

Table 2 Two-stage magnetic separation magnetic field strength test

Two-stage magnetic field strength (Oe) | product name | Yield(%) | grade(%) | Recovery rate(%) | ||

Fe | S | Fe | S | |||

2500 | Concentrate I | 35.40 | 62.70 | 0.257 | 43.68 | 5.23 |

Concentrate II | 12.76 | 61.26 | 0.211 | 15.38 | 1.55 | |

Tailings | 51.84 | 40.13 | 3.13 | 40.94 | 93.22 | |

total | 100 | 50.82 | 1.74 | 100 | 100 | |

3000 | Concentrate I | 36.21 | 60.83 | 0.272 | 43.34 | 5.66 |

Concentrate II | 8.07 | 60.47 | 0.280 | 9.60 | 1.30 | |

Tailings | 55.72 | 42.92 | 2.91 | 47.06 | 93.04 | |

total | 100 | 50.82 | 1.74 | 100 | 100 |

The results in Table 2 show that under the same conditions, the magnetic field strength of the two-stage magnetic separation is 2500 Oersted, and the magnetic grade is better. The Fe grade can reach 62.70%. If I and II concentrates are mixed, The cumulative yield was 48.16%, and the cumulative recovery was 59.06%. The content of S can be reduced to about 0.3%.

**Third, the determination of the rotational speed of the drum**

The pyrite cinder (dry mine) is sieved through a 100 mesh sieve, and the sieved product is ground on a rod mill for 5 min. The grinding concentration is C=70%, stirred for 5-8 minutes, and the magnetic field strength of a magnetic separation is 2000 Ã…. The magnetic field strength of the two-stage magnetic separation is 2500 Oersted, and the rotational speed of the drum is 16 rev/min, 18 rev/min, 20 rev/min, and 24, respectively. The test results are shown in Table 3.

Table 3 Magnetic separator drum rotation speed test

Speed â€‹â€‹(rev / min) | product name | Yield(%) | grade(%) | Recovery rate(%) | ||

Fe | S | Fe | S | |||

16 | Concentrate I | 33.70 | 62.44 | 0.253 | 41.41 | 4.90 |

Concentrate II | 15.36 | 60.33 | 0.218 | 18.22 | 1.92 | |

Tailings | 50.94 | 40.27 | 3.18 | 40.37 | 93.18 | |

total | 100 | 50.82 | 1.74 | 100 | 100 | |

18 | Concentrate I | 34.15 | 63.46 | 0.247 | 42.64 | 4.85 |

Concentrate II | 17.33 | 59.85 | 0.223 | 20.68 | 2.22 | |

Tailings | 48.52 | 38.42 | 3.33 | 36.68 | 92.93 | |

total | 100 | 50.82 | 1.74 | 100 | 100 | |

20 | Concentrate I | 29.33 | 62.83 | 0.314 | 36.26 | 5.29 |

Concentrate II | 15.43 | 60.13 | 0.236 | 18.28 | 2.09 | |

Tailings | 55.24 | 41.82 | 2.92 | 45.46 | 92.62 | |

total | 100 | 50.82 | 1.74 | 100 | 100 | |

twenty four | Concentrate I | 32.29 | 60.37 | 0.283 | 38.36 | 5.25 |

Concentrate II | 11.64 | 61.45 | 0.221 | 13.95 | 1.48 | |

Tailings | 56.06 | 43.23 | 2.89 | 47.69 | 93.27 | |

total | 100 | 50.82 | 1.74 | 100 | 100 |

The results in Table 3 show that under the same conditions, the magnetic separation effect is better when the rotation frequency f of the drum is 18 rev/min, and the grade of Fe can reach 63.46%. If the concentrates I and II are mixed, The cumulative yield was 51.84%, and the cumulative recovery was 63.22%. The content of S can be reduced to about 0.3%.

From the results of the above tests, it can be concluded that the magnetic separation process can obtain a higher grade, but the recovery rate and the yield are not ideal. The test has made a corresponding discussion on various factors affecting the magnetic field strength of the magnetic separation process and the rotational speed of the drum. The results show that the optimal magnetic separation process conditions are: when the grinding time is 5 min, the grinding concentration is C=70%, the stirring is 5-8 min, the magnetic field strength of a magnetic separation magnetic field is 2000 Oersted, and the magnetic field strength of the second magnetic separation 2500 Oersted, adjust the magnetic separator drum rotation frequency f to 18 rev / min. Under this condition, 63.46% of Fe grade was obtained, the cumulative yield was 51.84%, and the recovery was 63.32%. The content of S is about 0.3%.

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