Process for the manufacture of sodium carbonate crystals from minerals or solutions

A method of producing crystals from a sodium sesquicarbonate solution comprising the steps of:

• passing the sodium sesquicarbonate solution to a precipitator;
• adding methanol to the sodium sesquicarbonate solution in the precipitator such that a resultant liquor has methanol in a concentration of between 30% and 70% by volume;
• precipitating sesquicarbonate crystals from the resultant liquor;
• washing the precipitated sesquicarbonate crystals with an alcohol-containing solution having alcohol in a concentration of between 50 and 100 volume percent so as to control a density of said crystals;
• and
• drying the washed precipitated sesquicarbonate crystals.

A method of producing crystals from a solution containing a mixture of sodium carbonate and sodium bicarbonate comprising the steps of:

• passing the solution to a first precipitator, the mixture having a mole ratio of sodium carbonate to sodium bicarbonate of 5 or less;
• adding methanol to the solution in the first precipitator such that a resultant liquor has methanol in a concentration of between 30% and 50% by volume, said methanol being in residence with said solution for between 10 and 100 minutes;
• precipitating the sodium carbonate crystals and the sodium bicarbonate crystals from the resultant liquor;
• washing the precipitated sodium carbonate crystals and the precipitated sodium bicarbonate crystals with an alcohol-containing solution having alcohol in a concentration of between 50 and 100 volume percent;
• and
• drying the washed sodium carbonate crystals and the washed sodium bicarbonate crystals.

A method of forming rod-shaped sodium carbonate crystals from a sodium carbonate-containing solution comprising the steps of:

• passing the sodium carbonate-containing solution to a precipitator, said sodium carbonate-containing solution having a sodium carbonate concentration ranging from 300 g/l at 82.degree. C. to saturation;
• adding methanol to the sodium carbonate-containing solution in the precipitator such that a resultant liquor has methanol in a concentration of between 15% and 70% by volume, said methanol being in residence with said sodium carbonate-containing solution for between 80 and 100 minutes;
• precipitating sodium carbonate crystals from the resultant liquor;
• washing the precipitated sodium carbonate crystals with an alcohol-containing solution;
• and
• drying the washed precipitated sodium carbonate crystals.