I didn't want to post the following over yonder, as the residents are rather restless.
How do you interpret the 99.9998% purity results released last week? The only opportunity currently available is to compare these results with those of other nuclear graphite samples. Here’s an assessment published by Oak Ridge National Laboratory: http://info.ornl.gov/sites/publications/files/Pub32010.pdf
There were 12 synthetic and 7 natural graphite samples submitted to Oak Ridge for consideration for inclusion in their pebble bed reactor research program. None of these candidate graphites had impurity levels as low as those reported by Canada Carbon last week. To facilitate comparisons with these published results, I’ll give you CCB’s results in parts per million (ppm), as provided in the Oak Ridge report: boron 0.1, sodium 0.4, silicon 1.7, iron 0.09, zinc 0.08, and copper 0.1.
I want to caution readers, however, that these recent results do not automatically indicate that CCB’s graphite is better. The impurities were lower, but there are many other possible criteria. Moreover, the report is from 2011. It is entirely possible that these reported results have been improved upon, in the meantime.
Some have made light of the fact that CCB has reached similar purities in the past. The main thrust is that these new results have been obtained using commercial scale equipment, in a two step process that avoids hydrometallurgy altogether.
There are many variables that bear on value, but my experience leads to a simple rule of thumb that the value of graphite doubles with each additional 9 in the purity. Of course, it matters precisely what the impurities are, and the interpretation of their significance is both complex and application-specific.
Lar
