Artificial cryolite process

Claim 2

A PROCESS FOR THE MANUFACTURE OF SYNTHETIC CRYOLITE COMPRISING PROVIDING IMPURE AQUEOUS SOLUTIONS OF AIF3 AND NH4F CONTAMINATED WITH A MINOR PORTION OF PHOSPHOROUS COMPOUNDS, PRETREATING THE NH4F SOLUTION WITH A QUANTITY OF STRONG MINERAL ACID BEFORE ADMIXING SAID ALF3 THEREWITH TO PROVIDE AT ALL TIMES IN THE REACTION MIXTURE AN EXCESS OF HYDROGEN IONS, ADMIXING SAID AIF3 WITH A STOICHIOMETRIC EXCESS OF SAID NH4F THEREBY LOWERIN THE PH, TREATING SAID MIXTURED SOLUTIONS WITH A QUANTITY OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SODIUM CHLORIDE AND SODIUM CARBONATE WHEREBY THE PH OF THE REACTION MIXTURE IS LOWERED TO ABOUT 1.0 AND A SYNTHETIC CRYOLITE CONTAINING LESS THAN ABOUT 0.5% P2O5 IMPURITY IS PRECIPITATED THEREFROM.

Claim 3

IN A PRECIPITATION STEP WHEREIN ALUMINUM FLUORIDE AND AMMONIUM FLUORIDE ARE REACTED AS IMPURE SOLUTIONS CONTAMINATED WITH A MINOR PORTION OF PHOSPHORUS COMPOUNDS AND THE PRODUCT OF SAID REACTION IS FURTHER REACTED WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SODIUM CARBONATE AND SODIUM CHLORIDE, THE IMPROVEMENT COMPRISING PREHEATING ONE OF THE FLUORINE-CONTAINING REACTANTS WITH A SUFFICIENT EXCESS OF A STRONG MINERAL ACID TO MAINTAIN THEREIN AN ACID PH AFTER SAID FLUORINE-CONTAINING REACTANTS ARE COMIXED, PROVIDING IN THE MIXTURE OF SAID FLUORINE-CONTAINING REACTANTS AN EXCESS OF AMMONIUM FLUORIDE BY ADMIXING SAID AMMONIUM FLUORIDE WITH LESS THEN A STOICHIOMETRIC QUANTITY OF ALUMINUM FLUORIDE THEREBY FORMING IN SOLUTION SOLUBLE HEAVY METAL COMPLEXES AND AVOIDING THE FORMATION OF INSOLUBLE COLLOIDAL HEAVY METAL PHOSPHATES WHICH CONTAMINATE AND IMPART COLOR TO THE FINAL PRODUCT, AND FURTHER PROVIDING THROUGH THE AFORMENTIONED ACID TREATMENT A PH OF BELOW ABOUT 2 IN THE ULTIMATE REACTION MIXTURE WHEREIN ALL OF THE REACTANTS ARE COMIXED.

Claim 4

IN A PRECIPITATION STEP WHEREIN ALUMINUM FLUORIDE AND AMMONIUM FLUORIDE ARE REACTED AS IMPURE SOLUTIONS CONTAMINATED WITH A MINOR PORTION OF PHOSPHORUS COMPOUNDS AND THE PRODUCT OF SAID REACTION IS FURTHER REACTED WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SODIUM CARBONATE AND SODIUM CHLORIDE, THE IMPROVEMENT COMPRISING PREHEATING ONE OF THE FLUORINE-CONTAINING REACTANTS WITH A SUFFICIENT EXCESS OF A STRONG MINERAL ACID TO MAINTAIN THEREIN AN ACID PH AFTER SAID FLUORINE-CONTAINING REACTANTS ARE COMIXED, PROVIDING IN THE MIXTURE OF SAID FLUORINE-CONTAINING REACTANTS AN EXCESS OF AMMONIUM FLUORIDE BY ADMIXING SAID AMMONIUM FLUORIDE WITH LESS THEN A STOICHIOMETRIC QUANTITY OF ALUMINUM FLUORIDE THEREBY FORMING IN SOLUTION SOLUBLE HEAVY METAL COMPLEXES AND AVOIDING THE FORMATION OF INSOLUBLE COLLOIDAL HEAVY METAL PHOSPHATES WHICH CONTAMINATE AND IMPART COLOR TO THE FINAL PRODUCT, AND FURTHER PROVIDING THROUGH THE AFORMENTIONED ACID TREATMENT A PH OF BELOW ABOUT 2 IN THE ULTIMATE REACTION MIXTURE WHEREIN ALL OF THE REACTANTS ARE COMIXED.