Analysis Discussion of Experiments

In total, twelve tests of cyanatation were performed. From these, three used the ustullated material, implying in the need for twelve tests of ustullation in a rotational oven. Th4e conditions used in the tests of lixiviation. The six first tests did not present significant differences in the answers, in view that the tenor of gold in the material is very low, implying in a level of considerable insecurity. Besides this, the results are very approximate among each other. The two first are in a level of 23%; this because the bubbling was not very efficient, fact afterwards corrected. Within these tests the conditions of practice were tried to be bettered through an increase of the amount of existent cyanate in the environment of reaction (relation liquid/solid x concentration of CN); a dimminishing of granulometry of the material, placing it all under 200 nets, with the intention of trying to place the metal of interest more exposed; optimal conditions of oxydation (O2 in the reverse of the air).

In all cases, the recuperation was around 35%. As a next step, the test of best result was chosen (4) and the time of duration of the experiment increased to 30 hours. It was observed that the recuperation increased substantially, but the final value was still low for the objective of work.

In the laboratory an advance in two stages was chosen (N2/air) at 600°C, which from the results of defraction of x-rays of the product, the most interesting was proven for the case.

The product of four ustullations, in identical conditions, was submitted to cyanatation at the environment temperature. The result was, on the meantime, barely slightly superior. Now that the same material, submitted to lixiviation to heat, showed an elevated recuperation, both for the gold as for the silver, in a rate of reaction at a pretty high level. The level reached is sufficient to be considered excellent, even though the insecurities implied. It is characterized that individually the effects are in no way significant, but in conjunction the interaction is very positive, due to the fact that the curves traced are converted in similar recuperation and the interaction can present a very different behavior.