As one of the common mineral processing technologies, magnetic separation method is widely used in the separation of magnetite, manganese, ilmenite and other magnetic minerals by virtue of the advantages of simple equipment and good separation effect. But do you know how many factors affecting the magnetic separation process? And How does each factor affect the effect of the magnetic separation process?
According to the working principle of the magnetic separation process, we can know that the magnetic separation process mainly uses the magnetic differences among various minerals to realize mineral separation in the uneven magnetic field of various magnetic separation equipment. Thus, we can find two key factors that affect the magnetic separation process: one is the magnetic difference of minerals, another is the magnetic field distribution of magnetic separation equipment.
Then, we will explain how magnetic differences in minerals and magnetic separation equipment affect the effect of the magnetic separation process.
According to the magnetic differences, the minerals can be classified into strong magnetic minerals, weak magnetic minerals and non-magnetic minerals. It is because of the magnetism of the minerals that we can use the magnetic separation method to separate the different minerals. In other words, the magnetic differences in minerals are the basis of magnetic separation technology.
◆ For strong magnetic minerals, such as magnetite, pyrrhotite, magnetite hematite, etc., the specific susceptibility is more than 3.8×10-5m3/kg. The low-intensity magnetic separator (magnetic field intensity is 0.1-0.3T) is usually applied;
◆ For weak magnetic minerals, such as chromite, ilmenite, manganese ore, etc., the specific susceptibility is between 7.5×10-6 to 1.26×10-7m3/kg. The strong intensity magnetic separator (magnetic field intensity is 1-2T) is usually applied.
There are many factors that affect the magnetic properties of minerals, and the magnetic properties of minerals in different regions and deposits are not the same, and some of them are quite different. Therefore, when conducting the magnetic separation for the specific minerals in a certain region, we should judge the magnetic properties by the magnetic determination results of minerals, and then select the strong magnetic separation process or the weak magnetic separation process.
In order to enlarge the magnetic difference of minerals in the actual production, some magnetic separation plants usually change the magnetic properties of minerals with the help of some methods, such as magnetization roasting, alkali dipping magnetization, magnetization of magnetic species, etc., so as to change the magnetic properties of minerals and facilitate the magnetic separation.
The magnetic field is a special state in the space around a magnet. The magnet placed in a magnetic field is subjected to the magnetic force. The magnetic field intensity, gradient and direction (that is, whether the magnetic field is evenly distributed) in the separation space of the magnetic separation equipment often affect the effect of the magnetic separation process.
In the uniform magnetic field, the mineral particles are only affected by the steering force, the diversion of the mineral particle sizes is parallel to the field direction. In the heterogeneous magnetic field, the mineral particles are subject to the steering force and magnetic force. The minerals rotate and move towards the increasing magnetic gradients, which forms the rollover phenomenon, so the magnetically different grains are separated.
In addition, different magnetic separation equipment has a different design in the magnetic field distribution of separation space.
1. According to the strength of the magnetic field
Magnetic separation equipment can be divided into weak magnetic field separator (magnetic field intensity is 0.1t-0.2t), medium magnetic field separator (magnetic field intensity is 0.2t-0.5t) and strong magnetic field separator (magnetic field intensity is 0.5t-2.0t).
◆ The common weak magnetic field separators mainly include magnetic drum, wet permanentmagnetic separator, magnetic field screening separator, etc.
Take the magnetic drum as an example, its magnetic field presents alternating polarity of N and S around the circumference, and the magnetic field design is relatively simple.
The common strong magnetic field separators include dry magnetic separator, continuous high gradient magnetic separator, electromagnetic pulsating high gradient magnetic separator, etc. Most of them have a more complex magnetic field design.
Take dry magnetic separator as an example, the magnetic separator has few types, such as single row single roll type, double row double roll type, double row multiple roll type. After the coil is energized, the magnetic field is generated between the induction roller and the magnetic pole. The material is separated by the magnetic field that passes.
2. According to the type of magnetic field
Magnetic separation equipment can be divided into constant magnetic field separator, rotating magnetic field separator, alternating magnetic field separator and pulsating magnetic field separator.
In summary, it is not difficult to find that although the magnetic separation process is a kind of relatively simple mineral processing technology, it is not simple in the process design and selection. It is very necessary to understand the mineral properties, magnetic separation process and magnetic separation equipment in advance.
It is suggested to entrust the mineral processing equipment suppliers with qualification of mineral processing test to seek technical support, and choose the scientific and reasonable magnetic separation process and equipment according to the recommended results of ore dressing test, so as to ensure the perfect matching of technological process and ore properties, and the win-win situation of production indexes and economic benefit.
China a hematite magnetic separation project
Ore property:
The iron minerals in the hematite ore were mainly magnetite and hematite, the iron minerals distributed unevenly, and the gangue minerals were quartz.
Xinhai solution:
Stage grinding, gravity separation – magnetic separation – reverse flotation process.
Mineral processing index:
The selected grade was 23.15%, the concentrate grade was 65.95% and the tailings grade was 10.05%, which greatly improved the technical index of mineral processing. At the same time, the new mineral processing equipment and high-efficient mineral processing agents played a very good role, greatly promoting the progress of hematite ore processing technology, which was highly praised by the project customer.
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