3.4.3. Washing and Composition of the Cobalt Precipitate

The cobalt precipitate is washed with water at 80 ◦C at 1% solids for 5 min, filtered, dried overnight, weighed, and assayed. Table 9 gives the composition of the cobalt product obtained from 3 independent tests. Table 9 compares the average composition of the cobalt product to a target cobalt hydroxide feed for a cobalt refinery [18]. Results show that some tunings (likely at the cobalt precipitation stage) of the process are still required to lower the zinc and copper contents to meet the composition of the feed material for the Co-refinery.

**Table 9.** Composition (%) of the produced cobalt hydroxide and specifications for the feed of a custom cobalt refinery.


\*: Average ± standard deviation of three (3) replicated tests.

The XRD powder pattern of the cobalt product is shown in Figure 9. Results confirm that the produced material is under the form of CoO(OH) and Co(OH)2. The presence of these compounds was expected based on observations from other researchers [1].

**Figure 9.** XRD powder pattern of the cobalt product.
