Production of low bulk density product from sodium bicarbonate

A process for preparing a low bulk density and substantially lump-free product from sodium bicarbonate, which comprises the steps of:

• a. passing to a reaction zone a feed mixture comprising, by weight, (1) at least about 50% said sodium bicarbonate, (2) about 3 to 25% Wegscheider's Salt, and (3) about 5 to 20% water;
• b. heating said mixture in the absence of added carbon dioxide to a first temperature ranging between a temperature below which sodium bicarbonate is unable to be converted into nuclei of Wegscheider's Salt and a temperature above which substantial thermal decomposition of sodium bicarbonate and substantial formation of sodium sesquicarbonate occurs, for a first time sufficient to form Wegscheider's Salt nuclei and to avoid substantial caking and bulk density increase of the mixture;
• c. thereafter subjecting said heated mixture in the absence of added carbon dioxide at a second temperature ranging between a temperature at least about 10.degree.C. higher than said first temperature and a temperature less than the decomposition temperature of Wegscheider's Salt for a second time sufficient to prepare product particles containing at least 10% by weight Wegscheider's Salt in needlelike form;
• and
• d. recovering the product particles having a lower bulk density and a greater absorption property than said aqueous feed mixture.