Refining the precipitate from the vat process is going to be a little more complex than has been disclosed as can be seen from the report of July 2017 10-K.
An excerpt outlines some of the difficulties.
We located a previously mined area with interesting values – Ocho Hermanos. Mexus began to submit characterization samples to the above noted assay laboratories, in order to determine the range of Au - Ag values present. Mexus then began an investigation into recovery options by using material taken from the areas with the better values.
The above work was completed before any systematic exploration was done because if no recovery method could be found relatively quickly, the project would move more slowly because of the lead time involved. Mexus began work on an Environmental Impact Statement for the likely operational area (a total of 4 hectares to begin). In order to complete the EIS, figures for estimated tonnages were submitted to cover the hoped for volume. To date, no suitable recovery method was found due primarily to the partial oxidation of the principally sulfide deposit.
The main geologic feature of this project area is an apparent “manto” sulfide zone composed primarily of galena with some pyrite, arsenopyrite and possibly phyrrotite. Above this zone there is an oxide zone composed of iron and lead oxides. The sulfides themselves are partially oxidized. The deposit occurs in shallow water sediments (principally quartzites, with some limestone and shales) and can be best characterized as a skarn type deposit due to the presence of intrusive rocks within 1 kilometer.
Given the complex nature of the sulfide deposit and the partial oxidization of the material (indicated by the presence of yellow colored lead oxides), a satisfactory recovery method has not yet been found. Consequently, at this time, no further systematic work beyond the initial reconnaissance and characterization sampling has been completed.
That being said, the amateur hobby miner will have his hands full first in recovering gold and silver then successfully refining the precipitate at a reason cost. Somehow, I don't believe either he or his "experts" are up for the challenge.
