Magnetic separation is one of the main beneficiation methods for manganese beneficiation, and magnetic separator is the main equipment in this stage. In actual production, the operation of the magnetic separator has a very obvious influence on the separation index of manganese ore. The main operating factors include the thickness of the magnetic separator feed layer, the rotational speed of the magnetic separator cylinder, the separation baffle clearance, the feeding speed and the five aspects of water inlet control. This article will analyze the above five key points of operation to help you master the magnetic separation process of manganese ore.
Use the table of contents below to navigate through the guide:
The thickness of the feeding layer is the feeding amount, which is closely related to the particle size and magnetic mineral content of the raw ore fed into the magnetic separator. Generally, the feed layer of coarse-grained manganese ore is thicker than that of fine-grained manganese ore. The thickness of the feed layer for coarse-grained manganese ore should be about 1.5 times the upper limit of particle size, while for medium or fine-grained manganese ore, the thickness of the feed layer can reach 4 to 6 times the upper limit of particle size.
In the case that the content of magnetic minerals in the raw manganese ore is low, the thickness of the feeding layer should be appropriately reduced to avoid the magnetic ore particles located in the lower layer from being unable to be affected by the magnetic force and reduce the impact on the recovery rate of magnetic minerals. Similarly, when the content of magnetic minerals is relatively large, the thickness of the feeding layer can also be appropriately increased.
The magnetic field strength of the manganese ore magnetic separator barrel forms a regular distribution according to the design requirements. Taking the permanent magnet barrel magnetic separator as an example, the magnetic field strength will not change the magnetic field gradient due to the change of the current. Under this condition, controlling the rotating speed of the magnetic separator cylinder is one of the important operations to adjust the separation index, and its speed is mainly determined by the particle size of the manganese ore raw material and the operation requirements.
The rotating speed of the cylinder of the magnetic separator is mainly controlled by the frequency converter. When the raw manganese ore is strong in magnetism, the frequency conversion speed should be reduced. Conversely, when the raw manganese ore has weak magnetic properties, the frequency conversion speed should also be accelerated. In addition, under the condition of wet magnetic separation, the frequency conversion speed is lower than that of dry magnetic separation, and the rotating speed of the cylinder is also faster than that of dry magnetic separation. In the process of manganese ore fine-grained scavenging, the frequency conversion speed is lower than that of manganese ore selection, and the rotating speed of the cylinder is also faster.
The size of the separation baffle gap of the magnetic separator is the same as the rotating speed of the cylinder, which is mainly determined by the particle size of the raw manganese ore and the operation requirements. When the size of the gap is appropriate, the raw manganese ore can form a relatively obvious separation distribution zone on the cylinder. It can not only ensure the quality of the concentrate, but also effectively separate the tailings and improve the magnetic separation grade and metal recovery rate. When dealing with coarse-grained manganese minerals, the gap of the magnetic separation baffle is relatively large, in the range of 5~7mm. When dealing with fine-grained manganese minerals, the gap of the magnetic separation baffle is small, in the range of 3~5mm.
The feeding speed of the magnetic separator has a direct impact on the residence time of the manganese ore particles in the magnetic field and the mechanical force they receive. The faster the ore feeding, the shorter the residence time of the ore particles in the magnetic field, and the smaller the effect of the magnetic force. At the same feeding rate, the weak magnetic manganese minerals are weaker than the strong magnetic manganese minerals in the magnetic field, resulting in a decrease in the recovery rate. Therefore, when sorting manganese ore with weak magnetic properties, the feeding speed should be appropriately reduced.
In different sorting stages, the feeding speed of the magnetic separator is different. During the beneficiation stage, the raw manganese ore has many monomer minerals and strong magnetic properties, which can appropriately increase the feeding speed. However, in the process of sweeping, there are many conjoined minerals in the raw materials of manganese ore, and the magnetism is weak. At this time, the ore feeding speed can be reduced to improve the recovery rate.
When wet magnetic separation is used, the water inlet control of the magnetic separator is critical to the stability of the separation index. This requires a reasonable opening of the water inlet pipe of the magnetic separator to avoid excessive water inlet pressure. At the same time, the control of water concentration is also crucial. Excessive concentration of circulating water will affect the dispersion and sedimentation effect of manganese ore, thereby affecting the concentrate index. Circulating water concentration below 10% is ideal. If the circulating water is turbid, precipitation is required at this time for reuse.
The above are the five important operating points of the magnetic separator for manganese ore magnetic selection. The beneficiation process is relatively complex, and it is important to adjust the operating factors, but other factors also have an important impact on the manganese ore separation indicators. Therefore, Xinhai suggests that before formulating the manganese ore beneficiation plan, the beneficiation test should be done, and the beneficiation process plan should be formulated by scientific and reasonable means. In daily operation, it should be observed in time, and adjustments should be made in time according to the situation to ensure stable sorting effect and economic benefits.