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Physical & Chemical properties

Water solubility

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Description of key information

The solubility characteristics of the test material were demonstrated to be dependent on the initial loading rate of the test material.

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Additional information

The nominal loading rate of 1.0 g/l confirmed that the test material was essentially insoluble in water with only 5.1 mg/l of calcium, 7.1 mg/l of magnesium, less than 0.1 mg/l of silicon and less than 0.01 mg/l of aluminium, iron and manganese being detected in solution.

However, the solubility characteristics of the test material were then demonstrated to be dependent on the initial loading rate of the test material. Solubility of silicon, aluminium, iron and manganese remained negligible, but the calcium solubility was demonstrated to increase with an increased loading rate from the initial concentration of 5.1 mg/l up to 26.8 mg/l. Such dissolution was observed to be detrimental to the solubility of the previously dissolved magnesium compound(s), and the total dissolved magnesium concentration decreased from 7.1 mg/l to 2.7 mg/l. Due to this variability in the resulting calcium and magnesium concentrations with loading rate, no single loading rate could be identified as representative of five times saturation concentration in order to allow completion of the definitive test in accordance with the EC Method A6 guideline. The pH was determined as ≤10.6.