5 Types of Mineral Screening Operations

The screening operation mainly uses a sieve to divide the material with a wide particle size range (greater than 0.25 mm) into several levels according to the particle size. The different screening purposes also largely affect the selection of screening equipment. According to the purpose of screening, we usually divide screening operations into five types: independent screening, auxiliary screening, preliminary screening, selection screening and dewatering screening.

The purpose of the independent screening operation is to obtain the final product requested by the mineral processing plant. For example, in ferrous metals, iron-rich ores with higher iron content are often sieved into different particle sizes, and then large-sized iron ore of acceptable size enters the smelting operation, and the fine ore is smelted after being agglomerated or sintered. For this case, it is recommended to use the circular vibrating screen or linear screen. Both can be widely used for screening various granular or bulk solid materials, which have low requirements on material size, and are especially suitable for processing large materials.

Auxiliary screening is mainly used in the crushing operation of the mineral processing plant, which plays an obvious auxiliary role in the crushing operation. First, before the ore enters the crushing operation, the qualified fractions are pre-screened, and the fine fractions present in the ore will have a negative impact on the crusher production, and at the same time prevent the ore from being over-crushed, thereby reducing the crushing efficiency. The second is to control the particle size of the broken product. After inspection and screening, the unqualified size will be returned to the crusher, just as the closed loop of the grinding machine and the classifier is beneficial to improve the grinding efficiency. Checking the screening can significantly improve the crusher production capacity. However, checking and screening will increase a part of the investment and complicate the equipment configuration of the crushing workshop. Therefore, it is generally only used in the crushing section of the last crusher to check and screen, and combined with the pre-screening to form a pre-inspection screening closed loop. Usually, in the auxiliary screening operation stage, the screening equipment manufacturers will customize according to the nature of the ore, the crushing process and the capacity. Most of the plants usually use circular vibrating screens, linear vibrating screens and self-centering vibrating screens.

Preliminary screening is mainly to provide different grades of selected materials for the classifying operation, which are often used before gravity and magnetic separation process. The selected materials are sieved and classified into coarse, medium and fine particles before gravity and magnetic separation. You can determine the screening order according to its own production sequence, from fine to coarse, from coarse to fine or mixed screening. After all, in the separating process, different separating equipment have different separating granularity requirements, which have different effects on the separating effect. If the particle size is too large, it cannot be separated, and the particle size is too fine to be recycled. Linear vibrating screens are the best choice for preliminary screening. The linear vibrating screen has a large feeding range, and the mesh size design is more flexible than other types, generally between 0.15mm-80mm, which is more suitable for preparing different particle size requirements of the screening operation.

If the distribution of the useful components in the material differs greatly in each particle size, the particle size can be obtained by screening and classifying. And then the low-quality particle size can be sieved to improve the material grade. In the production practice, many iron ore dressing plants select the screening effect by fine sieving in the iron concentrate re-grinding cycle, and improve the iron concentrate grade by means of fine screening. In this situation, the light linear vibrating screen can fully exploit its high precision and perfectly achieve fine particle screening.

The purpose of dewatering screening is to remove water, mud and media from the slurry. It is often used in the dewatering of washing products in coal processing plants and de-medium of heavy-medium beneficiation products. Compared with ordinary vibrating screens, it is recommended that you use dewatering screens.

The above are the 5 common types of screening operations. In the mineral beneficiation process, the screening equipment used for different screening purposes are also different. You should make a reasonable choice when selecting vibration screen for your production line.

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