Dry strong magnetic separation of manganese ore (1)

The magnetic separation process is carried out in the magnetic field of the magnetic separator by means of the action of force and mechanical force on the ore particles. Different magnetic ore particles move along different trajectories and are sorted into two or more separate beneficiation products.
The trajectory of the recovered magnetic particles is determined by the ratio of the magnetic force to the mechanical force acting on the magnetic particles, and the trajectory of the non-magnetic ore particles is determined by the mechanical force.
In order for the magnetic separation process to proceed normally, the magnetic force should be greater than the combined force of the mechanical force and the force required to overcome the inertia of the moving magnetic particles, namely:


Where F MQPH - the magnetic force acting on the magnetic ore;
F XlX - mechanical force opposite to the direction of the magnetic force;
F NH - the inertial force of magnetic ore particles, related to the speed of motion.
Substances can be divided into two categories according to their magnetic properties: diamagnetic substances and paramagnetic substances. Minerals can be classified according to the specific magnetic susceptibility from the perspective of magnetic separation, and generally can be classified into four categories.
(1) strong magnetic minerals: than the susceptibility of greater than 3000x10 -6 cm 3 / g, available weak magnetic field of 0.15T selected separator, magnetic iron ore, hematite, manganese black magnesium ore.
(2) Medium magnetic mineral: the specific magnetic susceptibility is 600x10 -6 cm 3 /g~3000x10 -6 cm 3 /g, which can be recovered by a 0.3~0.6T medium magnetic field magnetic separator, such as illusion hematite.
(3) Weak magnetic minerals: the specific magnetic susceptibility is 15X10-6cm 3 /g~600x10 -6 cm 3 /g, which needs to be recovered by a strong magnetic separator of 0.6~1.8T, such as manganese mineral, iron, Qin, tungsten, etc. .
(4) non-magnetic minerals: coefficient than the magnetization <15x10 -6 cm 3 / g of substance, such as scheelite, cassiterite and non-metallic quartz, calcite and the like.
The specific magnetic susceptibility of weak magnetic minerals can be determined by the apparatus of Figure 1.

Pour the mineral sample ground to a particle size of less than 0.2mm into a small glass bottle. The latter is hung on a weighing pan of the analytical balance. The glass bottle containing the sample is first weighed, and then the glass bottle containing the standard sample is weighed. They are placed in a certain area of ​​the special electromagnet magnetic field, a certain current is passed through the electromagnetic winding coil, and the magnetic attractive forces acting on the sample and the standard sample are respectively measured.
The specific susceptibility of the sample to be tested can be calculated by the following formula:

Where X is the specific magnetic susceptibility of the standard sample, cm 3 /g;
F 0 - the gravitational force acting on the standard sample, g;
Q 0 - the quality of the standard sample, g;
F 1 - acting on the sample on the gravitational force, g;
Q 1 - the quality of the sample being tested, g.
Different currents are passed through the coil, measured three or four times, and then the average value of the specific magnetic susceptibility of the sample to be tested is calculated. Using a standard sample typically manganese pyrophosphate, its specific susceptibility to 117x10 -6 cm 3 /g.[next]
Looking up the data, the specific magnetic susceptibility of minerals is listed in Table 1.

Table 1   Specific magnetic susceptibility of common minerals


Particle size / m

Specific magnetic susceptibility / (cm 3 ·g -1 )

Mineral color



20000×10 -6




5400×10 -6


Titanium ore


399×10 -6


Mica iron ore


292×10 -6

Dark red shiny



290×10 -6

Dark red



80×10 -6

Yellow brown



47×10 -6


Manganese ore

0.1381×10 -6



Manganese ore


28×10 -6




27×10 -6


Black manganese soil


75×10 -6

Dark red

Manganese ore


120×10 -6




50~250×10 -6


Black manganese ore


50~250×10 -6


Manganese silicate


<15×10 -6


Meta-manganese ore


<150×10 -6


Tungsten manganese ore


66×10 -6

Black brown

Black mica


40×10 -6




75×10 -6


Spot copper mine


14×10 -6




10×10 -6

Light cyan



18×10 -6




10×10 -6




90×10 -7

Red brown



48×10 -7




43×10 -7

Yellow and white



14×10 -7


According to the data of the former Soviet Union Mineral Processing Research Institute, the magnetic separator is given according to its mode: upper feeding and lower feeding; selecting environment: dry and wet; magnetic field generating method: electromagnetic induction, permanent magnet block; processing ore granularity: coarse, Medium and fine particles; magnetic separator: flat ring, vertical ring, cylinder type, roller type, disc type, belt type, etc., and produce a wide variety of magnetic separators. Manganese ore is a weak magnetic mineral. It should be sorted by a magnetic separator with strong magnetic field. For the current magnetic separation of manganese ore in China, for the convenience of description, it is more appropriate to classify according to the order of the size of the ore. As described below. [next]
First, the coarse particle strong magnetic separator
According to the practice of the manganese ore industry, the coarse particle grade refers to ore with an ore particle size greater than 5 mm.
The use of coarse-grained magnetic separation as a roughing operation for manganese ore is an easy and effective measure. From the end of the 1970s, China began to test the Ñ„380mmx400mm electromagnetic induction roller type strong magnetic separator, followed by Shenyang Mining Machinery Plant, Changsha Black Metal Mine Design and Research Institute, Pingle Manganese Mine, Zhangpu Manganese Mine, Taojiang Manganese Mine, Bayi Manganese Mine, and Wood. The GE Manganese Mine and other units have successively developed different types of dry electromagnetic induction roller type strong magnetic separators for processing coarse-grain grade ore. In the 1990s, Changsha Research Institute of Mining and Metallurgy, Beijing Research Institute of Mining and Metallurgy, Guilin Tianyun Mineral Processing Machinery Plant and Liuzhou Yuanjian Magnetic Equipment Manufacturing Plant successively developed different types of permanent magnet type strong magnetic separators. Applied in industrial production. The technical performance of the more important electromagnetic and permanent magnet magnetic separators is shown in Table 2. It should be specially stated that certain performance parameters, such as the magnetic induction intensity processing amount of the sorting area, are provided by the manufacturer's manufacturer's manual, and the data analysis from various aspects may have a large gap with the field measured data.

The 80-1 type coarse-grain upper-feeding electromagnetic induction double-roller strong magnetic separator was developed and put into production in 1980, and was selected by the Ministry of Metallurgy in 1982. [next]

The 80-1 type strong magnetic separator is a feature of various types of magnetic separators that have been successfully developed and applied to industrial production at that time, and has been developed for the requirements of coarse-grain manganese ore sorting. It uses the difference in specific magnetic susceptibility of different ores to achieve the purpose of sorting. as shown in picture 2. When the mineral particles pass through the magnetic field of the induction roller of the magnetic separator, different magnetic trajectories are generated due to the different magnetic forces of the magnetic ore particles and the non-magnetic ore particles, so that the ore particles are sorted into two products according to different mineral magnetic properties. It is discharged separately by the miner to achieve the purpose of sorting.
The structure of the magnetic separator is shown in Figure 3. The mainframe is composed of six parts.

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