Mix It Up

With increased infrastructure development, cement producers have an opportunity for big business – that is, if they can keep up and maintain maximum outputs. That is why it is important to use the most productive tools for screening and sizing. Rather than sticking to woven wire or polyurethane media throughout the screen deck, some operation managers find they can reduce wear, lessen screen change-outs, and increase the open area by choosing strategic combinations of screen media.

The difference between using one type of screen media versus the optimal blend of screen media can add up to thousands of dollars in downtime and expense in a year. Improving screening productivity starts with analysing the operation, consulting with an expert, learning proper installation and maintenance techniques, and trying new solutions.

What is the problem?

The first step toward selecting the best combination of screen media involves answering several questions. What material is being processed? Is the screen media reaching a suitable lifespan for the operation? And what sort of challenges are occurring with the current screen media and at what phase of screening?

Start by considering the types of materials going through the vibrating screen. Material size, weight, and abrasiveness all come into play during the screen media selection process.

Next, look at the vibrating screen itself and complete a vibration analysis. Some analysis systems are designed to safely monitor vibrating screen performance in real-time and detect irregularities before small problems lead to diminished performance or bigger issues.

Consider the three phases material goes through as it passes over the vibrating screen deck, from layered, to basic, to sharp. Producers can customise the screen deck by choosing screen media suitable for each phase by accounting for open area and wear life to maximise productivity.

In the layered phase, as material of all sizes hits the screen deck, the media should handle a deep bed depth, high impact and a mix of coarse and fine particles. Heavy-duty options incorporating polyurethane, rubber, or metal plate excel in withstanding high top sizes and abrasion.

Material should stratify in the middle of the deck during the basic phase, and near-size and oversize particles should be at the top of the material being screened. For this stage, choose a type of media that combines maximum open area and wear life. Some manufacturers offer hybrid screen media options that pair polyurethane’s durability with open area similar to woven wire.

Virtually all undersize material should have fallen through the screen media by the time it reaches the sharp phase at the discharge end, where near-size and oversize particles should be in direct contact with the media. Woven wire or self-cleaning screen media provides the maximum open area here, where any remaining undersized particles should fall through, preventing contamination of the final product.

A vibrating screen operator should also examine wearability to determine whether media in the three phases is reaching maximum potential. If screen media is being changed too often, consider switching to something more durable. It is a good idea for producers to complete an inspection of screen media weekly. Inspect openings carefully; wear becomes apparent if the openings in engineered media begin to round. Also, make sure tensioning remains correct by checking screen tension weekly.

Next, examine discarded screen media for signs of problem areas, such as broken wires, wear areas, pegging, or blinding. Many operators experience premature wear on their screen media by not choosing a blend of media that can handle heavy material along with large amounts of abrasive fines. Others use media that is not well-suited for the operation and, as a result, have carryover or contamination because of pegging and blinding. This unwanted material in the screened pile results in the added cost and time of rescreening. Also, broken screens mean costly unscheduled change-outs. It takes about an hour to shut down a vibrating screen and change one screen media section. While an hour may not seem like a long time, the lost production will result in thousands of dollars off the bottom line.

All of these signs indicate there is likely a better screen media option for at least one phase of screening, if not all three.

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Read the article online at: https://www.worldcement.com/special-reports/29122023/mix-it-up/