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Click to add WeChatIron ore is an important raw material for industrial production, playing a vital role in driving industrial production. However, due to the depletion of rich iron ore resources, the development of complex and difficult-to-beneficiate iron ore resources has become a focus of industry. These ores exhibit polymetallic coexistence, making individual separation extremely difficult, increasing beneficiation costs, and posing a potential environmental pollution risk. Therefore, it is necessary to conduct in-depth analysis and research on beneficiation processes for different difficult-to-beneficiate iron ores to improve beneficiation indicators and resource utilization rates. This will accelerate the development and utilization of iron ore and promote the economic benefits of beneficiation plants. This article will introduce several low-grade iron ore beneficiation technologies.
Magnetite quartzite is a low-grade iron ore resource, mainly composed of magnetite and quartz.
When beneficiating this type of ore, magnetic separation can be used because there is a significant difference in the magnetic susceptibility between magnetite and quartz. Typically, the beneficiation process for magnetite-quartzite involves crushing, followed by pretreatment using an autogenous mill and a ball mill, three stages of fine grinding, and then multi-stage magnetic separation. Therefore, to eliminate interference from individual gangue minerals in magnetite-quartzite, a process combining staged grinding and magnetic separation is necessary, which effectively reduces the amount of material processed in the next stage.
Magnetite ore belongs to skarn ore, mainly composed of iron(III) oxide, and has a wide distribution. Magnetite ore has a similar magnetic susceptibility to magnetite quartzite, so magnetic separation can be used to recover magnetic minerals. A combination of crushing and magnetic separation can effectively recover the ore. The specific process involves two to four stages of crushing followed by one to two stages of dry magnetic separation, and wet magnetic separation can also be performed to obtain higher-quality iron concentrate.
Sometimes, magnetite beneficiation processes combine magnetic separation with flotation or flotation with magnetic separation to effectively improve the grade of iron concentrate. For desliming magnetite ore, a standard magnetic separator is sufficient; a fully circulating water supply system effectively recycles water, reducing production costs. For the beneficiation of fine-grained, disseminated magnetite ore, the focus is on improving the beneficiation process and upgrading and modifying the beneficiation equipment. New crushers are used to reduce grinding energy consumption and decrease ore particle size to increase the processing capacity of grinding equipment.
Hematite beneficiation methods include washing, gravity separation, flotation, magnetic separation, and roasting magnetic separation. Fine beneficiation can be carried out using flotation and electrostatic separation. Different beneficiation processes can be selected according to the different properties of the ore. When coarse-grained or lumpy hematite ore is mixed with lean materials, suspension beneficiation is used. Jigging beneficiation is used for granular ore, and spiral concentrators or high-intensity magnetic separators can be used for medium and fine-grained ore. For the development and utilization of fine-grained disseminated hematite, flotation or roasting magnetic separation is used.
The beneficiation of hematite-magnetite often employs magnetic separation + gravity separation, magnetic separation + flotation, gravity separation + magnetic separation + flotation, or combined beneficiation processes. Some beneficiation plants first use gravity separation to recover hematite, and then use magnetic separation to recover magnetite from the gravity separation tailings. Sometimes flotation can also be used for fine selection, with fine screening before the tailings separation. The magnetic separation + gravity separation process first uses a weak magnetic field to recover magnetite, and then uses gravity separation to recover hematite from the magnetic separation tailings. In the magnetic separation + flotation process, hematite is first recovered using flotation, then coarse-grained hematite and magnetite are recovered using gravity separation, and finally fine-grained magnetite is recovered using magnetic separation.
Limonite ore, besides limonite as its main mineral, also contains small amounts of hematite and ferruginous iron. Gangue minerals mainly include quartz, calcite, and clay minerals. Due to the complexity of these mineral compositions, multiple beneficiation methods are required. Currently, a combined process of washing, gravity separation, and magnetic separation is widely used. Limonite first needs to be washed to remove surface dirt and impurities to improve the purity of the raw ore. Then, gravity separation is used for initial enrichment of limonite. Finally, magnetic separation is used to further separate iron-bearing minerals and gangue minerals, improving the purity of the iron concentrate to meet the needs of subsequent smelting.
When iron ore also contains niobium and rare earth minerals, a combined beneficiation process of weak magnetic-strong magnetic-flotation is required. First, the ore is ground to a certain particle size. Then, the magnetic iron minerals are recovered using weak magnetic separation. Weak magnetic separation to separate iron-containing silicates can achieve preliminary enrichment of rare earth and niobium minerals. Finally, flotation is used for recovery, ensuring high-quality rare earth and niobium concentrate products.
The above is a brief description of beneficiation technology for more difficult-to-process iron ore. For the beneficiation of low-grade iron ore resources, a more detailed process design is needed to maximize resource utilization. Due to their low iron content and complex gangue composition, the beneficiation process must be optimized by considering the specific physical and chemical properties of the ore, as well as economic efficiency and production needs. Typically, the beneficiation process for low-grade iron ore may include multiple stages such as pretreatment, grinding, classification, magnetic separation, and gravity separation, and may require the introduction of flotation or other special processes to improve the iron content and recovery rate of the final concentrate.
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