Sand Moisture Control is important in the manufacturing and processing stages. Giant sand piles may sit exposed to the weather rain or shine impacting the moisture content of the whole pile and external versus internal moisture profiles. It rained for 3 days and yesterday it was hot bright sunshine, then the exterior is dryer than the interior. Near Infrared Moisture Transmitters provide an immediate measurement of sand moisture on the belt. The transmitter is mounted between 8 and 18” (200 – 450 mm) above the product with an air purge of 3 – 10 psig to keep the sight lens clean. Large digital display, proportional analog output (4 – 20mA) and Ethernet communications are available.
Sand is sold by weight and specification, meaning that there is range of acceptable moisture level in the sand upon delivery. If the sand moisture exceeds that moisture level it can be rejected or purchased at a significant discount. If the sand moisture is lower than that specification the supplier is leaving money on the table by not adding water to increase the weight while still being in specification.
Sand moisture can be controlled by dryer temperature, throughput and re-moisturizing. Dryer Temperature adjustment may be used if a known incoming run of sand is high in moisture. As a practical process control option dryers have too slow a response time for minor variations that still need to be optimized to maximize efficiency (profit). Dryer throughput is the best control parameter as it can increase or slow throughput through the dryer based on moisture. When raw product is over dried or oven has over dried a moisture spray station may be triggered by the PLC. Moisture is money for Sand Suppliers. An upper level in-specification sand moisture allows End User to optimize for specific application and maximize profits for supplier.