Abstract Merrill slime is contacted with a gold chloride solution to cement out gold and dissolve base metals. The separated solids are treated in a known type of process by chlorination with elemental chlorine, separation of the chlorinated solution and precipitation of gold powder by means of a reductant. The precipitation is partial and the remaining solution is used for the cementation step. The gold powder is separated and subjected to special washing techniques for the removal of adsorbed impurities. A molar ratio of Cl/Au of about 4 after chlorination is aimed at to minimise the solubility of silver chloride. After removing solid impurities this ratio is raised to ensure that any dissolved silver remains in solution when gold is subsequently precipitated.
Inventors
👤 Herbert J. Bovey
👤 Dennis A. Temple
👤 Basil J. Goldswain
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-25 09:19
CPC Classifications
C; C22; C22B; C22B11/00; C22B11/06
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
116 words
A process for treating a gold bearing Merrill slime, comprising the steps of: contacting said slime with a gold chloride solution with agitation, whereby dissolved gold is caused to be cemented out on said slime and base metal impurities are caused to go into solution; separating the cemented slime from the solution; suspending the cemented slime in water and chlorinating the suspension by passing chlorine gas through it; separating the residual solution from the solids; precipitating gold powder from the residual solution by the addition of less than a stoichiometric amount of a suitable reductant so that a proportion of the gold remains in the residual solution and separating, washing and drying the precipitated gold powder.
Claim 2
Dependent Claim
116 words
A process for treating a gold bearing Merrill slime, comprising the steps of: contacting said slime with a gold chloride solution with agitation, whereby dissolved gold is caused to be cemented out on said slime and base metal impurities are caused to go into solution; separating the cemented slime from the solution; suspending the cemented slime in water and chlorinating the suspension by passing chlorine gas through it; separating the residual solution from the solids; precipitating gold powder from the residual solution by the addition of less than a stoichiometric amount of a suitable reductant so that a proportion of the gold remains in the residual solution and separating, washing and drying the precipitated gold powder.
Claim 3
Dependent Claim
22 words
The process of claim 1, in which the residual solution left after separation of gold powder is used for contacting the slime.
Claim 4
Dependent Claim
30 words
The process of claim 2 in which the molar ratio of Cl/Au in the chlorinated suspension is adjusted to be about 4 before separating the solution from the cemented slime.
Claim 5
Dependent Claim
21 words
The process of claim 3 in which the molar ratio of Cl/Au is increased before precipitating gold powder from the solution.
Claim 6
Dependent Claim
25 words
The process of claim 1 in which the precipitated gold powder is washed with an aqueous solution of ammonia, ammonium chloride and EDTA after separation.