Method of controlling sulfide concentration to prevent iron contamination in the processing of trona

Claim 1

THE METHOD OF PREPARING SUBSTANTIALLY IRON FREE CRYSTALLINE SODIUM SESQUICARBONATE FROM CRUDE TRONA MINERAL CONTAINING IRON WHICH COMPRISES DISSOLVING THE CRUDE TRONA IN A RECIRCULATING SODIUM SESQUICARBONATE MOTHER LIQUOR CARRYING SUFFICIENT SULFIDE DISSOLVED THEREIN TO SUBSTANTIALLY DEPRESS THE IRON SOLUBILITY IN SAID RECIRCULATING MOTHER LIQUOR AT THE POINT OF SOLUTION OF THE CRUDE TRONA MINERAL, SEPARATING INSOLUBLES FROM SAID SOLUTION WITH A DECREASE OF ABOUT ONE-SIXTH IN THE AMOUNT OF SULFIDE PRESENT AT THE POINT OF SOLUTION OF THE CRFUDE TRONA MINERAL, CRYSTALLIZING SODIUM SESQUICARBONATE FROM SAID SOLUTION WHILE VOLATILIZING ABOUT ONE-THIRD OF THE SULFIDE PRESENT AT THE POINT OF SOLUTION OF THE CRUDE TRONA MINERAL FROM THE CRYSTALLIZER SOLUTIO TO CAUSE A PORTION OF THE IRON HELD AS SULFIDE IN SAID SLUTION TO REMAIN WITH THE MOTHER LIQUOR, SEPARATING THE CRYSTALS FROM SAID SOLUTION, RETURNING THE MOTHER LIQUOR TO DISSOLVE MORE CRUDE TRONA, AND ADDING SUFFICIENT SULFIDE TO SAID RECIRCIRCULATING MOTHER LIQUOR TO MAINTAIN THE SULFIDE CONCENTRATION THEREIN BETWEEN 100 AND 1000 P.P.M.

Claim 2

THE METHOD OF PREPARING SUBSTANTIALLY IRON FREE CRYSTALLINE SODIUM SESQUICARBONATE FROM CRUDE TRONA MINERAL CONTAINING IRON WHICH COMPRISES DISSOLVING THE CRUDE TRONA IN A RECIRCULATING SODIUM SESQUICARBONATE MOTHER LIQUOR CARRYING SUFFICIENT SULFIDE DISSOLVED THEREIN TO SUBSTANTIALLY DEPRESS THE IRON SOLUBILITY IN SAID RECIRCULATING MOTHER LIQUOR AT THE POINT OF SOLUTION OF THE CRUDE TRONA MINERAL, SEPARATING INSOLUBLES FROM SAID SOLUTION WITH A DECREASE OF ABOUT ONE-SIXTH IN THE AMOUNT OF SULFIDE PRESENT AT THE POINT OF SOLUTION OF THE CRFUDE TRONA MINERAL, CRYSTALLIZING SODIUM SESQUICARBONATE FROM SAID SOLUTION WHILE VOLATILIZING ABOUT ONE-THIRD OF THE SULFIDE PRESENT AT THE POINT OF SOLUTION OF THE CRUDE TRONA MINERAL FROM THE CRYSTALLIZER SOLUTIO TO CAUSE A PORTION OF THE IRON HELD AS SULFIDE IN SAID SLUTION TO REMAIN WITH THE MOTHER LIQUOR, SEPARATING THE CRYSTALS FROM SAID SOLUTION, RETURNING THE MOTHER LIQUOR TO DISSOLVE MORE CRUDE TRONA, AND ADDING SUFFICIENT SULFIDE TO SAID RECIRCIRCULATING MOTHER LIQUOR TO MAINTAIN THE SULFIDE CONCENTRATION THEREIN BETWEEN 100 AND 1000 P.P.M.