Wet weather and damp feed material can severely delay or hamper your screening process. Aggregate materials tend to become sticky and pack up. Blinded screen decks can change material gradations, greatly reduce production, force equipment shutdowns and even cause equipment damage. All this affects customer satisfaction, selling price and profit, not to mention the obvious potential danger when entering confined spaces for cleaning blinded screen cloths or plugged chutes.
Fortunately, there are real and effective options to keep screens running clean and making you money.
SELF-CLEANING WIRE SCREENS
Self-cleaning wire screen cloths such as the new generation Flex-Mat 3 have been gaining wide acceptance throughout the industry for their long wear life, screening accuracy, increased productivity and excellent resistance to pegging and blinding.
Polyurethane strips centred on each screen deck crown bar support allow individual crimped wires to vibrate independently at different frequencies, preventing material from accumulating between wires as it typically does with woven wire. Flex-Mat can also last up to three times longer than woven wire.
For real problem areas, there is the scope to drop down a wire size or two and opt for stainless steel rather than high tensile or abrasion resistant OptimumWire.
Available as tensioned cloths with aperture sizes ranging from 0.5mm to 102mm or modular panels, the Flex-Mat 3 has solved thousands of severe screening problems worldwide and significantly increased throughput on any screen compared with woven wire, square or slotted cloth.
Flex-Mat 3 has up to one-third more open area per screen, allowing far more in-spec product per hour.
Rubber cloths have been used for screening ores and aggregates for more than 40 years and are widely recognised for long wear life and relatively good self-cleaning. However, their wider use has been somewhat limited by the significant reduction in open area, which was more a function of the labour-intensive manufacturing process and high cost of tooling than the durability of a high open area rubber screen cloth.
The modern automated rubber punching presses have totally changed the game and Hi-flow rubber cloths can now be tailor made to suit most applications and production requirements.
Hi-flow cross-tensioned and end-tensioned rubber screen cloths have about 30 per cent more open area than the traditional rubber cloth. The additional open area not only increases production capacity during drier times but it also improves the flexibility and self-cleaning qualities to better cope when feed material is damp and sticky.
In extreme conditions it?s best to select a thinner, softer rubber making the cloth even livelier. Being thinner means accurate sizing is much easier to achieve and remains more constant throughout the life of the cloth.
Don?t expect Hi-flow rubber screen cloths to last as long as a standard rubber cloth. They probably won?t. Hi-flow cloths are purpose-built and custom-designed to screen clean and produce more.
Modular screen panels often suffer quite badly from blinding, as do some larger heavy-duty moulded scalper panels. A clever, innovative design combined with Nepean Rubber?s proprietary low friction anti-sticking rubber compound can go a long way towards relieving blinding.
LINERS AND CHAINS
Blinded screens can also lead to blocked under-pans, chutes and costly downtime. At worst, catastrophic failure can occur when fines pack up under the screen box.
Nobody likes cleaning out chutes and sometimes it can be downright dangerous, particularly when freeing up fines from overhead. A self-cleaning inflatable liner system can be designed for most applications and budgets. All you need is a source of low volume, low pressure compressed air and 240 volts of electricity. Incorporating the same low friction rubber technology as moulded screen panels, the liners will keep chutes clear.
Another option if screens keep blinding is Nepean?s innovative poly ball chain. Impact from the 50mm ? polyurethane balls striking the screen surface is often enough to clear away any fines and blinded apertures. Poly ball chains are suitable for use with woven mesh, self-cleaning wire and synthetic screen cloths.
WHAT ARE YOUR OPTIONS?
To sum it up, buying the right screen media requires far more than the occasional telephone call, fax or quick visit from the sales rep. The most appropriate screen media for each application, properly sized and installed, will make a huge difference in production, wear life and cost per tonne.
Trying to understand all of the options and issues shouldn?t be your job. Look for manufacturers and suppliers that have this expertise and will invest the time and effort to continually maximise your screening efficiency for performance and cost savings and that will be there if challenges arise.
Ask yourself these questions:
- Does your local sales rep or manufacturer visit frequently?
- Does he/she understand your production goals, product specs and issues, and how it affects screening?
- Does he/she examine all of your plant?s screening operation (the feed, screen box condition, material flow, throughput of each screen) for potential problems or opportunities to increase production?
- Does he/she review the worn out or damaged screen cloth for signs of premature wear and/or breakage?
- Does he/she make solid recommendations for each application and follow up after installation?
- What level of knowledge and support can he/she offer?
- Does the supplier of your screen media want to find the solution or offer better ideas to increase your production or reduce your operating costs?
- Does he/she understand your spec issues and how critical they are?
- Does he/she understand your customers and what they require?
- How will he/she perform in emergency situations?
- Will they stand behind their product and recommendation?
- Will he/she get dirty and inspect the screens personally?
If you consider these tough issues, you?ll be well on your way toward finding the right screen media supplier for the long haul. Then you can focus on other critical functions.
At your request, Nepean Rubber can conduct an on-site screening plant audit that clearly identifies screening problems and bottlenecks, as well as recommending changes to improve production rates and material specifications and help your operation produce more material for
less cost. ?
Source: Nepean Rubber & Plastics