Method for preparing dense sodium carbonate from crude trona

Claim 1

PROCESS FOR PREPARING DENSE SODIUM CARBONATE FROM CRUDE TRONA COMPRISING: DRY MINING THE CRUDE TRONA, CRUSHING THE CRUDE TRONA, CALCINING THE CRUDE TRONA AT A TEMPERATURE AND FOR A TIME SUFFICIENT TO CONVERT THE CRUDE TRONA INTO CRUDE SODIUM CARBONATE, DISSOLVING THE CALCINED CRUDE SODIUM CARBONATE IN WATER CONTAINING LESS THAN 7% NA2CO3 THEREIN TO FORM AN AQUEOUS SOLUTION, CLARIFYING AND FILTERING THE AQUEOUS SOLUTION OF CRUDE SODIUM CARBONATE TO REMOVE INSOLUBLES, HEATING THE FILTERED AQUEOUS SOLUTION OF SODIUM CARBONATE TO A TEMPERATURE ABOVE ABOUT 95*F. AND BELOW THE BOILING POINT OF THE SOLUTION, EVAPORATING A PORTION OF WATER FROM THE SODIUM CARBONATE SOLUTION TO PRODUCE SODIUM CARBONATE MONOHYDRATE CRYSTALS, SEPARATING SAID MONOHYDRATE CRYSTALS FROM THE SOLUTION, RECYCLING THE MOTHER LIQUOR TO THE EVAPORATOR, DISCARDING A PORTION OF SAID RECYCLED MOTHER LIQUOR TO AVOID BUILDUP OF IMPURITIES TO A POINT WHERE THEY WILL CRYSTALLIZE, PASSING SAID SEPARATED CRYSTALS OF MONOHYDRATE TO A CALCINER TO CONVERT SAID MONOHYDRATE TO SUBSTANTIALLY ORGANIC-FREE DENSE SODIUM CARBONATE.