Weak Magnetic Iron Ore Beneficiation Technology

Single-Component Weak Magnetic Iron Ore | Polymetallic Weak Magnetic Iron Ore

1. Single-Component Weak Magnetic Iron Ore

Includes hematite, siderite, limonite, and hematite-siderite ores from sedimentary-metamorphic, sedimentary, hydrothermal, and weathering deposits. Production experience with this ore type is limited due to its diverse mineral composition and wide grain size distribution.

Multiple beneficiation methods exist, commonly categorized into two types:

(1) Roasting Magnetic Separation

Roasting magnetic separation is an effective method for processing fine to ultrafine (<0.02 mm) weakly magnetic iron ores. When ore mineralization is complex and other methods yield unsatisfactory results, magnetized roasting magnetic separation should be employed. Long-term production experience exists for reducing roasting of 75–20 mm lump ore in vertical furnaces; however, production practice for magnetized roasting of fines below 20 mm is limited. Currently, fines are commonly separated using strong magnetic separation, gravity separation, flotation, or combined processes.

(2) Gravity separation, flotation, strong magnetic separation, or combined processes.

Flotation is a common method for separating fine to ultrafine weakly magnetic iron ores. Two principle processes exist: positive flotation and reverse flotation. The former is suitable for quartz-rich hematite ores without easily floatable gangue minerals, while the latter is suitable for ores with easily floatable gangue minerals. Both have production practice.

Gravity separation and high-intensity magnetic separation are primarily used for coarse-grained (20–2 mm) and medium-grained weakly magnetic iron ores. For coarse-grained and extremely coarse-grained (>20 mm) ores, gravity separation typically employs heavy media or jigging; Medium to fine-grained ores employ fluidized-bed gravity separation methods such as spiral concentrators, shaking tables, fan sluices, and centrifugal separators. Dry induction roller magnetic separators are commonly used for coarse and medium-grained ores, while wet induction magnetic separators are preferred for fine-grained ores. Currently, due to the low concentrate grade achievable from fine-grained ores via strong magnetic separation and the relatively low unit processing capacity of gravity separation, combined strong magnetic-gravity separation processes are often employed. Strong magnetic separation discards large volumes of acceptable tailings, followed by gravity separation to further process the strong magnetic concentrate, thereby enhancing its grade.

2. Weakly Magnetic Iron Ore Containing Multiple Metals

Primarily hydrothermal and sedimentary hematite or siderite ores containing phosphate or sulfide minerals. Iron minerals in such ores are typically recovered via gravity separation, flotation, magnetic separation, or combined processes, while phosphate or sulfides are recovered by flotation.

Hydrothermal apatite-bearing hematite ores and copper-sulfide siderite ores can be processed by flotation.

Sedimentary phosphatic goethite ores can be separated from iron via flotation, but often prove difficult to concentrate into phosphatic concentrates, significantly reducing iron recovery rates. Consideration may be given to removing coarse gangue, smelting high-phosphorus pig iron, and subsequently recovering phosphatic fertilizers from steel slag.

Weathered deposits' iron caps contain brown iron ore with non-ferrous metals, often accompanied by copper, arsenic, tin, and other associated elements without distinct minerals. Separation from iron via mineral processing is challenging, and methods like chlorination roasting are under investigation. In lateritic nickel-chromium-cobalt laterite deposits, associated elements also lack distinct mineral forms. Methods such as roasting-ammonia leaching and magnetic separation are under investigation.

(Technical parameters and data mentioned herein may be updated with product upgrades. Click website customer service for the latest equipment specifications.)

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