From our Ore to Your Door - Episode 14: Screening, Crushing and Blending

From our ore to your door, Episode 14: SCREENING, CRUSHING AND BLENDING

As the magnesite decrepitates during calcination, the resulting magnesia breaks down into different size fractions. These can range from 20mm down to fine powders less than 30 microns in size. The first step in processing calcined magnesia is the Caustic Calcine Upgrade - screening, crushing, and blending.

SCREENING
Each of our three MHFs have separate calcination outputs, with individual dry screening processes that separate the magnesia into four size distributions per output. We continuously collect samples from each of the twelve particle streams and test them twice daily for chemical and particle sizing.

CRUSHING AND BLENDING
An advantageous characteristic of our magnesia is that differing percentages of impurities, such as silica and calcium oxide, align to each of the magnesia size fractions. This means we can select each product stream individually and blend them together to get exactly the correct chemical composition for the products being manufactured. Some of the calcined magnesia fractions are lower in calcium and silica than the magnesite fed into the multiple hearth furnace, hence the term Caustic Calcine Upgrade.
At this point, we make adjustments in line with our sales requirements, and crush the magnesia (reducing the size of larger particles) with impact hammer mills and additional screening.

BLENDING
With the magnesia analysed and separated into twelve silos, we use high accuracy weighfeeders to blend the product and discharge from the silos at exact chemical specifications, depending on what we need for downstream processing.

Pictured: Aaron Olsson, site manager Parkhurst