FAQs of Magnetic Separation

Introdução: Magnetic separation is an important separation technology in the field of mineral processing and is widely used for the sorting and recovery of various types of ores. Whether it involves ferrous ores such as iron and manganese ores or the extraction of non-ferrous metals such as tungsten and tantalum ores, magnetic separation technology plays a crucial role. This article systematically summarizes the most common questions regarding magnetic separation technology to help you gain a comprehensive understanding of its principles, applications, and equipment selection.

China is one of the earliest countries to understand the magnetic phenomenon. The ancient Chinese discovered that magnets can attract iron but not gold, silver, copper, or other metals. They also discovered the directivity of magnets and produced the earliest compass – Sinan.
A aurora é também formada pela ação de um campo magnético.

1. What is Magnetic Separation?

A method of mineral separation in a non-uniform magnetic field based on the magnetic difference of various minerals.

2. What Are The Applications Of Magnetic Separation?

Separação de minérios de metais ferrosos (ferro, manganês, crómio, etc.);
Non-Ferrous Metal (tungsten, tantalum, etc.) and rare metals separation;
Separação de minérios não metálicos (amianto, diamante, caulino, etc.);
Remoção de componentes magnéticos de materiais sólidos e resíduos.

3. What Is The Magnetic Separation Working Principle?

Sob a ação de lavagem do fluxo de água, as partículas de minério soltam-se.
In the magnetic field, the magnetic ore particles are aggregated to form a lump of magnetic material, which is attracted to the cylinder. As the cylinder rotates, the non-magnetic mineral, such as gangue, falls off, and the magnetic lump that is finally attracted to the cylinder surface is the concentrate ore. The concentrate goes to the edge of the cylinder, which has the weakest magnetic strength, and is discharged into the concentrate tank under the action of the flushing water. Non-magnetic or weakly magnetic minerals are left in the slurry and finally discharged, which are the tailings.

4. What’s The Precondition of Magnetic Beneficiation?

(1) There must be an uneven magnetic field of sufficient strength and gradient.
(2) There must be a certain magnetic difference between the minerals, that is, the specific susceptibility of the two minerals is different.
(3) For minerals with strong magnetic properties, the magnetic force they receive is greater than the sum of various mechanical forces.

A condição necessária para a separação das partículas magnéticas do minério é que a força magnética das partículas magnéticas do minério seja maior do que a força combinada das forças mecânicas que se lhe opõem.

5. Why is Magnetic Separation Only In Non-uniform Magnetic Fields?

Num campo magnético uniforme, o minério está apenas sujeito a um binário, pelo que a direção do seu eixo longo é paralela à direção do campo magnético.
Num campo magnético não uniforme, as partículas de minério não são apenas afectadas pelo binário, mas também pela força magnética. As partículas de minério são rodadas e movidas na direção em que o gradiente do campo magnético é aumentado, e finalmente absorvidas na superfície do pólo magnético.
Desta forma, as partículas magnéticas com diferentes propriedades magnéticas são separadas, pelo que a separação magnética só pode ser conseguida num campo magnético não uniforme.

6. What is The Classification of Magnetic Minerals?

Minerais fortemente magnéticos: It is easy to pick out in a weak magnetic separator with magnetic field strength H=900~1800Oe.
There are a few such minerals, mainly magnetite, pyrrhotite, titanomagnetite, zinc-iron spar, and the like.
Minerais magnéticos fracos: In the magnetic field strength H = 6000 ~ 2000 Oersted, magnetic beneficiation is somewhat difficult, and some are easy.
Mainly iron-manganese ore, hematite, specularite, limonite, siderite, rhodochrosite, etc.; some titanium, chromium, tungsten-containing minerals; biotite, hornblende, epidote, chlorite, olivine, garnet, pyroxene, etc.;
Minerais não magnéticos: The magnetic separation method is not available currently.
Existem muitos minerais deste tipo, incluindo:

• Some metal minerals – chalcopyrite, galena, sphalerite, molybdenite, scheelite, cassiterite, gold, etc.
• Most non-metallic minerals – sulfur, coal, graphite, diamond, gypsum, kaolin, etc.
• Most of the rock-forming minerals – quartz, feldspar, calcite, and so on.

7. What is The Purpose of Magnetization Roasting For Weakly Magnetic Iron Ore?

The purpose of magnetization roasting:

• Turn the weak magnetic iron mineral into a ferromagnetic iron mineral;
• Remove gas and crystal water from ore
• Make the ore structure loose, reduce grinding cost
• Improve mineral processing efficiency.

8. How to Change The Surface Magnetism?

(1) Alkali leach magnetization
The NaOH solution leaches the siderite FeCO3, forming Fe(OH)2 on the surface of the ore; the leaching compound is reoxidized to γ-Fe2O3 and Fe3O4.
(2) Hydrophobic
A lixiviação alcalina dissocia a superfície do mineral e o sabão de ácido gordo forma uma película de ferro de ácido gordo hidrofóbico com o componente de ferro no ferro ou na lama que permanece na superfície do mineral, cobrindo a superfície do mineral para aumentar a suscetibilidade magnética.
(3) Magnetic seeds
Ajuste a lama, adicione sementes magnéticas (como pó de magnetite finamente moído) e surfactante para aderir seletivamente as sementes magnéticas ao mineral alvo para melhorar as propriedades magnéticas do mineral alvo, e depois separe e recicle-o com equipamento de separação magnética de campo magnético fraco.
(4) Magnetization agent
The additional magnetic species is selectively attracted to the target mineral by the magnetizing agent to increase its magnetic properties.

9. What Are The Types of Magnetic Separators?

Since the 1980s, with the advent of bismuth-iron-boron high-magnetic rare-earth permanent magnet materials, the types of magnetic separators have become increasingly diverse. Classification of magnetic separation equipment:

• According to the strength of the magnetic field: weak, medium, and strong.
• According to the media, dry type, wet type separator.
• De acordo com o tipo de campo magnético: constante, rotativo, alternado, pulsante.
• De acordo com a estrutura do separador magnético: tipo cilíndrico, tipo de correia, tipo de disco, tipo de anel, etc.

Selecting the right magnetic separation equipment is crucial for improving mineral processing efficiency and economic benefits. JXSC Mining Equipment offers a wide range of separadores magnéticos, including wet, dry, high-intensity, and triple-disc models in various specifications to meet different mineral processing needs. If you require professional technical consultation, equipment quotes, or mineral processing plant design services, please feel free to contactar-nos for assistance.

Whether you want to learn about the principles of magnetic separation technology or need to select the right magnetic separation equipment, our professional technical team can provide comprehensive solutions to help you achieve optimal mineral separation results.