Process for producing a carbonate composition

An apparatus for the production of hydroxide and carbonate compositions, comprising:

• means for reacting calcium hydroxide with sodium carbonate under conditions effective to produce a first aqueous slurry containing sodium hydroxide and calcium carbonate as a precipitate;
• means for filtering the first slurry to remove an aqueous sodium hydroxide solution therefrom;
• means for diluting the first slurry with water;
• means for comminuting the precipitated calcium carbonate in the first slurry;
• and
• means for classifying the first slurry containing comminuted calcium carbonate particles to remove a second aqueous slurry therefrom, which second slurry contains fine calcium carbonate particles.

An apparatus for the production of hydroxide and carbonate compositions, comprising:

• a causticizer for reacting calcium hydroxide with sodium carbonate under conditions effective to produce a first aqueous slurry containing sodium hydroxide and calcium carbonate as a precipitate;
• a filtration device that receives the first slurry from the causticizer and filters the first slurry to remove an aqueous sodium hydroxide solution therefrom;
• a grinder that receives the first slurry from the filtration device and grinds the precipitated calcium carbonate in the first slurry;
• and
• a classifying device that classifies the first slurry containing ground calcium carbonate particles to remove a second aqueous slurry therefrom, which second slurry contains fine calcium carbonate particles.

An apparatus for the production of a carbonate slurry, comprising:

• a mixing tank wherein a ground carbonate product is combined with a fresh aqueous slurry of carbonate particles;
• a classifying device capable of separating a coarse fraction of carbonate particles larger than a predetermined size from the slurry to obtain a slurry of fine carbonate particles;
• a grinder capable of comminuting the coarse carbonate fraction to form the ground carbonate product;
• a coarse fraction tank interposed between the classifying device and the grinder wherein water is added to the coarse fraction prior to grinding;
• conduits connecting the mixing tank, classifying device, coarse fraction tank and grinder in a closed circuit;
• and
• a pump for circulating the carbonate slurry through the conduits.