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5 Screening Purpose That Must Be Understood Before Selecting Screening Equipment

Xinhai 2018-11-07(16:53:04) -1484 -1997

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Before selecting screening equipment, you need to understand the screening purpose first, In fact, the difference in the screening purpose also greatly affects the choice of screening equipment. Depending on the screening purpose, we usually divide the screening work into 5 categories

  1. 1. Independent screening

  2. 2. Auxiliary screening

  3. 3. Preparation for screening

  4. 4. Selection of screening

  5. 5. Dewatering screening

As we all know, the screening work is an indispensable work in the entire ore dressing production, because the screening equipment plays different roles in mineral dressing plant for different screening purpose. 

  • In the crushing process, the screening equipment can screen out the fine fraction before being fed into crusher, increase the crusher productivity and avoid over-crushing; 

  • before separating, the screening equipment can divide the ore into several screen grades according to the particle size and then process it. It can improve the separating effect;

  • In the ore dressing plant, sometimes the screening equipment can also be used to remove moisture from the material or separate the slurry, such as the removal medium of the heavy medium beneficiation product. 

The screening work 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. Usually, people choose the different screening equipment firstly from the nature of the material itself, often ignoring the original screening purpose. 

So, what is the difference between the 5 screening categories that we metioned above? What kind of screening equipment is suitable for each category? 

Let's get started!

1. Independent screening

The screening purpose of the independent screening work is to obtain the final product requested by the customer. 

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 a round vibrating screen or a linear vibrating screen. Both screening equipment 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.

2. Auxiliary screening

Auxiliary screening is mainly used in the crushing work of the ore dressing plant, so its screening purpose is to play an obvious auxiliary role in the crushing work. 

  • 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. 

  • Control the particle size of the crushed 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 output. Most of the plants usually use circular vibrating screens, linear vibrating screens and self-centering vibrating screens.

3. Preparation for screening

The screening purpose of preparation for screening is mainly to provide different grades of selected materials for the classifying work, which are often used before gravitimatric and magnetic separation work. The selected materials are sieved and classified into coarse, medium and fine particles before gravitimatric and magnetic separation. 

The mine owner 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 has 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 preparation. The linear vibrating screen has a large feeding range, and the mesh size design is more flexible than other types, generally between 0.15 mm-80 mm, which is more suitable for preparing different grain size requirements of the screening work.

4. Selection of screening

If the distribution of the useful components in the material differs greatly in each particle size, the particle size can be obtained by sieving and classifying, and then the low-quality grain size can be sieved to improve the material grade. So the screening purpose in this part is to screen out some finest particle and avoid over-grinding. 

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 scenario, the light linear vibrating screen can fully exploit its high precision and perfectly achieve fine particle screening.

5. Dewatering/de-sludge/de-media Screening

As the name implies, the screening purpose of this type of the screening equipment is to remove water, mud and media from the material. Disperse materials (such as slurry, mud, slurry, etc.) with a large amount of water are used as screening raw materials to remove water or fine particles, which are common in such as coal preparation plants, washing product dewatering and heavy medium beneficiation products. In addition to media and so on. 

Compared to ordinary vibrating screens, mineral processing experts recommend the use of dewatering screens.

Conclusion

From this we can see that in the mineral dressing process, the vibration screening equipment used for different screening purpose is also different. The working position of the different screening equipment for the mineral dressing line is also different. We should make reasonable choice on selecting fitful screen for our own production line.

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