Mineral Powder and Granular Silo Level: Material and Radar Selection

Mineral powders and granules range from fine low-dielectric dust to coarse abrasive aggregate. The same silo may receive products with different moisture, bulk density and flow behavior, so one generic level setting is rarely enough. Filling impact, dust clouds, angle of repose, segregation, bridging and wall buildup affect both the surface and the instrument. Radar can provide non-contact continuous measurement, while point switches may provide high or low alarms. Selection requires material data, silo geometry and operating cycles to be considered together, with explicit limits for inventory accuracy and lost-signal behavior.

Characterize every stored material

Record mineral type, particle size distribution, dielectric response, bulk density, moisture, abrasiveness, temperature and tendency to adhere. Include the lowest-signal and highest-wear cases.

Describe pneumatic or mechanical filling, discharge aids, vibration and cleaning. Product changeover may leave deposits that create a different surface or false echo.

Map surface and structure

Survey silo height, diameter, roof, cone, nozzle, outlets and dead-stock regions. Mark fill pipes, braces, wear liners and aeration equipment.

Estimate fill and discharge profiles for each product. A measurement aimed at a steep slope may change rapidly even when total inventory changes slowly.

Choose radar and mechanical protection

Compare frequency, beam angle, antenna, sensitivity, range, nozzle fit and process temperature. Confirm that the material provides adequate return at maximum distance.

Keep the antenna away from direct impact and severe abrasion. Any shield or purge must preserve the beam and comply with dust-hazard requirements.

Configure for changing products

Capture echo curves for empty, low, mid and high levels and for representative products. Use separate configurations only when changeover is controlled and traceable.

Set tracking and lost-echo response from filling rates. Do not allow a frozen value to remain indistinguishable from a stable process level.

Define inventory uncertainty

Convert distance to volume using actual geometry and the selected beam location. Include surface profile, dead stock and wall buildup in the volume estimate.

Use representative bulk density for mass conversion and state its variability. Avoid presenting sensor millimetres as equivalent mass accuracy without an uncertainty calculation.

Commission and maintain

Verify level and PLC scaling at known points and compare inventory with weigh or delivery data over cycles. Test high-level shutdown and communication faults.

Inspect alignment, antenna buildup and nozzle condition after unexplained errors. Revalidate after material, liner, inlet, outlet or geometry changes.

Set product-change and wear controls

Create approved settings and signal baselines for each material family, including the weakest return and most abrasive service. Prevent operators from selecting a configuration that does not match the actual silo contents.

Inspect liners, fill chutes, shields and antenna exposure at planned intervals. Progressive wear or accumulated coating can change both the process surface and the fixed echoes long before the transmitter reports a device fault. Record wear measurements and echo changes together so maintenance decisions use evidence rather than calendar replacement alone or assumptions about service life.

Engineering checklist

List material electrical and mechanical properties.
Map surface profiles and dead stock.
Protect the sensor from impact and abrasion.
Validate echoes for representative products.
State volume and mass uncertainty honestly.
Test alarms and maintain signal evidence.

Frequently asked questions

Can one setup handle different minerals?

Sometimes, but signal strength, density, buildup and surface behavior must be validated for every intended product.

Why is mass accuracy worse than level accuracy?

Geometry, surface shape and bulk-density variation add uncertainty after the distance measurement.

When is a point switch needed?

Use one for independent high or low protection when continuous measurement alone does not satisfy the risk requirement.

Need a project-specific review? Send process data, drawings, photographs and acceptance criteria through our contact page.