Choosing and using
December 1, 2006 By: Pit & Quarry Editorial Staff Pit & QuarryWhether you're looking for new screening products or trying to get more out of the products you have, here are tips you can use.
Aggregate producers who know the ins and outs of screening can achieve three important goals: maximization of production efficiency, minimization of downtime, and ultimately increased profitability. Products and applications vary from operation to operation, of course, but top screening professionals offer this advice: Do your homework, and make sure the screening system you are using is suited to the job.
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Factors such as centrifugal force and amplitude (throw) affect screen performance, so it's essential to pay attention to the details of the application. Clogging and wedging can also occur if the throw is too small. Meanwhile, inclined screens must operate at the correct combination of slope and direction to maximize production.
If you're in the market for a new screening system, consider tons per hour; the type of material to be screened and its weight; the amount of moisture; whether the screening system is suited for applications that vary in temperature, abrasiveness and corrosiveness; and installation and maintenance costs.
Following are tips and case studies to help with screening applications and product decisions.
Meeting market demand
What happens when external factors such as market growth and adverse weather conditions impact your operation's ability to meet the increasing demand and capture your share? Here's how one producer teamed with his local screening and crushing field specialist to address screening challenges.
Over the past three to five years, Yahara Materials, Waunakee, Wis., has experienced a dramatic increase in demand for clear stone products. These products are widely used for underground pipe and highway bedding to provide proper drainage. The product specifications required clean rock with minimal fines. Yahara Materials needed to find a way to increase its capacity to effectively capture its share of this growing market.
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Yahara Materials operates seven 6 x 20, triple-deck, portable crushing plants that are equipped with slotted, Tri-Lock screens. These slotted screens became very problematic when faced with ever-changing soil conditions found at various locations owing to increased moisture content present during the winter and spring months.They were unable to remove enough fines to get the product within specification. The slotted screens would blind over, halting production and minimizing throughput.
Upon the recommendation of their local Unified Screening & Crushing Co. – Twin City Wire — Yahara Materials changed to a Stainless Steel "W" style screen. This change greatly increased the flexibility of the screen and increased product flow. The W style screen is composed of straight tension wires, W shaped wires and custom cross wires. Three wire sizes are used for a harmonic screening effect. This product allows greater open area than a square-opening screen, and, increases throughput with this "harmonic effect."
In addition, the W slots perform well during wet and difficult screening conditions. "Blinding and sizing problems can be eliminated," said Paul Burcalow, general manager at Yahara Materials. "We have experienced a 15-percent increase in production since the change to the W slots, and the W slot screens last longer. They actually last two to three times longer than anything we previously used in this application. The increase has allowed us to increase our capacity to capture our share of the growing demand for clear stone. Plus these clean screens have saved us an investment in a new Wash Plant for our concrete applications. Our production is up, throughput improved, especially in wet conditions, and we've saved an additional step in processing materials. It was a win-win."
 Flex-Mat 3 is neither woven wire nor polyurethane, but combines the benefits of both. It is designed to prevent blinding and plugging. |
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