Spectrophotometric method for the determination of gold

Claim 1

A PROCESS FOR DETECTING AND DETERMINING THE AMOUNT OF GOLD PRESENT IN GEOLOGIC MATERIALS CONTAINING GOLD VALUES AND NOT CONTAINING SILVER, PALLADIUM, THALLIUM, ANTIMONY, CADMIUN OR URANIUM IN AMOUNTS THAT WOULD INTERFERE WITH THE DETECTING AND DETERMINING KPROCESS COMPRISING (A) ROATING A MEASURED, PARTICULATE SAMPLE OF GEOLOGIC MATERIAL; (B) CONTACTING SAID ROASTED SAMPLE WITH A CONCENTRATED HYDROBROMIC ACID-BROMINE SOLUTION FOR A PERIOD OF TIME SUFFICIENT TO DISSOLVE OUT ELEMENTAL GOLD AND GOLD COMPOUNMDS PRESENT IN THE SAMPLE AND FORM A PREGNANT ACID SOLUTION; (C) DILUTING SAID PREGNANT ACID SOLUTION TO FORM A DILUTED SOLUTION; (D) MIXING SAID DILUTED SOLUTION INCLUDING ANY SOLID SAMPLE RESIDUE REMAININING AFTER THE ACID CONTACTING STEP WITH AN ETHYL ETHER SOLUTION KTO EXTRACT GOLD VALUES FROM THE DILUTED SOLUTION AND RESIDUE, AND FORM, ALONG WITH REMAINING RESIDUE, AND ETHYL ETHER EXTRACT PHASE AND AN ACID RAFFINATE PHASE: (E) SEPARATING SAID EXTRACT PHASE FROM THE REAFFINATE AND REMAINING RESIDUE; (F) CONTACTING SAID ETHYL ETHER EXTRACT PHASE WITH A DILUTE HYDROBROMIC ACID SOLUTION MORE DILUTE THAN THE PREVIOUSLY MENTIONED DILUTE HYDROMOMIC ACID SOLUTION TO FORM AN ETHYL ETHER REAFFINATE PHASE FROM THE ACID EXTRACT PHASE; (G) SEPARATING THE ETHYL ETHER RAFFINATE PHASE FROM THE ACID EXTRACT PHASE; (H) EVAPORATING COMPLETELY SAID ETHYL ETHER REAFFINATE PHASE TO FORM A SOLID RESIDUE; (I) DISSOLVING SAID SOLID RESIDUE IN A DILUTE SOLUTION OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF AMMONIUM ACETATE AND NITRILO TRIACETIC ACID; (J) ADDING 4,4''-BIS(DIMETHYL AMINO) THIOBENZOPHENONE (TMK) IN AN ORGANIC CARRIER SOLVENT TO THE THUS FORMED SOLUTION OF SOLID RESIDUE (I) TO YIELD A TEST SOLUTION WITH A RED COLOR THE INTENSITY OF WHICH IS PROPORTIONAL TO THE AMOUNT OF GOLD PRESENT THEREIN; AND (K) DETERMINING THE AMOUNT OF GOLD IN THE TEST SOLUTION.