A PCB Sensor for Determining the Ferromagnetic Material Concentration of New Zealand Sands

The mining and processing of ironsands in New Zealand (NZ) have an annual economic impact of over $220M. Expanding this industry would have a positive economic impact, but this could also lead to significant environmental impacts. To mitigate these issues, a low-cost printed circuit board (PCB) sensor was developed to quickly assess the ferromagnetic content of sand at potential ironsand mining sites. The sensor requires a small sand sample, which minimizes environmental impact during the site evaluation process. Ironsand and nonironsand sand samples were collected from NZ sites and used to evaluate the sensor's performance. Test data demonstrated that the sensor measured the ferromagnetic particle content of sand mixtures from 0% to 100% ironsand concentration with a sensitivity of 180.5 nH per % concentration and an R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> value of 0.9849 based on sample mass. Based on sample volume, the sensor demonstrated a sensitivity of 181.2 nH per % concentration with an R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> value of 0.9803.