除铁是基于被分离物料中不同组分的磁性差异，采用不同类型的除铁机将物料中不同磁性组分分离的选矿方法。磁铁的磁力所作用的周围空间称为磁场。表示磁场强弱的物理量称为磁场强度，常用符号H 表示，单位是A/m 。矿物磁性差异是磁选的依据。矿物的磁性可以测出，根据其磁性强弱程度可把矿物分为三类：强磁性矿物、弱磁性矿物、非磁性矿物。在除铁机的磁场中，强磁性矿物所受磁力最大，弱磁性矿物所受磁力较小，非磁性矿物不受磁力或受微弱的磁力。
Iron removal is based on the magnetic difference of different components in the separated material. Different types of iron removers are used to separate different magnetic components in the material. The surrounding space acted by the magnetic force of a magnet is called a magnetic field. The physical quantity indicating the strength of the magnetic field is called the magnetic field strength, which is usually expressed by the symbol h, and the unit is a / m. The magnetic difference of minerals is the basis of magnetic separation. According to the degree of magnetism, minerals can be divided into three categories: strong magnetic minerals, weak magnetic minerals and non-magnetic minerals. In the magnetic field of the iron remover, the strong magnetic mineral receives the most magnetic force, the weak magnetic mineral receives the less magnetic force, and the non-magnetic mineral does not receive the magnetic force or the weak magnetic force.