Automating for Maximum Production

• Achieve consistent quality
• Reach maximum output
• Improve operating efficiency
• Reduce maintenance
• Save on energy costs
• Improve resource allocation
• Avoid unscheduled downtime
• Improve competitiveness
• Strengthen the bottom line

Crusher Performance

Crusher performance has a big impact on operating costs and product yield. The ideal is a steady inflow and an even output of consistent quality material by maintaining the desired recirculating load. Underfeeding a crusher allows oversized material to pass through, missing the opportunity for particle interaction. This wears out equipment, wastes energy, and increases the recirculating load, Overfeeding results in inconsistent quality as well as spillage that requires cleanup. It may cause blockages that shut down the plant. You can ensure smooth flow of material to and from the crusher by installing level monitoring, weighing, and process protection devices at key,

Monitoring material levels provides important control information, not only for the crushers but also for inventory and load out. A practical solution is non-contacting ultrasonic level measurement consisting of a transducer aimed at the material being measured and connected to a transceiver that processes and displays the information,

• Primary crusher: Monitor the level of material in the rock box below the primary crusher to avoid surging the belt or blocking the feed system resulting in costly downtime.
• Secondary and tertiary crushers: Monitor the level in the surge bin to maintain consistent feed rates to the crusher. Continuous monitoring of the level in the crusher bowl helps you "choke feed" a crusher so it operates at maximum efficiency, using less energy and reducing wear and tear. High and low level alarms ensure optimum feed right into the crusher bowl.
• Primary jaw crusher: Use level measurement to control infeed. This helps avoid blockages, reduce spills and cleanup.
• Primary gyratory crusher. Level measurement can be used as an alarm on blockages in the rock box to reduce shutdowns. Maintaining an optimum level prevents projectile discharge, increases conveyor belt life, and minimizes damage.
• Screening plant: Level monitoring equipment alerts the operator in case of plugged chutes so he can take action minimize plant downtime. It improves throughput, and helps avoid spills, cleanup and lost production time.
• Stockpiles: Monitor the height of product stockpiles for inventory purposes, and to avoid overstacking or equipment damage. Maintaining a proper stockpile height prevents material degradation from a long fall onto a low stockpile,
• Radial stacker: Monitor the height of the pile to automate the movement of a radial stacker.
• Load out: Ultrasonic level devices can help drivers position vehicles properly for loading and unloading. They can also monitor the level in load out bins to ensure enough material is available for continuous loading.

Weighing Material

Conveyor belt scales provide important information to help you optimize operations,

• Primary crusher. Use a heavy duty belt scale on the primary conveyor to measure plant feed rate. This provides crusher performance feedback, and totals production to simplify trend analysis, accounting, schedules, and maintenance.
• Secondary crusher. Use a belt scale to monitor second stage crushing and plant feed rates. It monitors recirculating loads and provides inventory totals for the secondary surge pile. This enables crusher optimization, remote monitoring and trend analysis,
• Surge pile or secondary surge: Use a belt scale to monitor and control the feed rate of material to the plant. Use a belt scale for PID control of vibratory feeders discharging from the surge pile. This helps you maintain consistent and controllable feed rates to optimize product crushing and screening.
• Tertiary crushers: Using a belt scale to weigh recirculating material helps you adjust crusher operation to optimize performance.
• Product stockpiles. A belt scale provides production rate and inventory tracking information.
• Load out: A belt scale can be used for custody transfer and to generate a "sales ticket:’

Plants can avoid the high cost of process interruptions and equipment breakdowns by using motion failure alarms or acoustic sensors. These sensors react instantly to changes in motion and solids flow to warn of blockages, product absence, or equipment failure. When they detect a change outside the programmed parameters, they signal an alarm. An operator can then clear the blockage to quickly resume production, or fix equipment before serious damage occurs, Early detection prevents problems from escalating, saying time and money and keeping your process running smoothly.

Level measurement devices and belt scales help you maintain consistent feed rates to the crusher, ensuring a full load and maximum plant performance. Process protec- tion devices give you an early warning system to protect your process and equipment. Automation in these key areas can greatly improve overall efficiency and results.

The information for this article was produced by Siemens Milltronics Process Instruments Inc., Peterborough, Ont., www.siemens-milltronics.com .

By Robert L. Consedine, Editor

Aggregates and Roadbuilding Magazine
4999 St Catherine Street West. Suite 315
Westmount, Quebec H3Z 1T3
Tel: (514) 4879868 Fax: (514) 4879276
EMail: rocktoroad@sympatico.ca

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