NOVELTY - Calcium product (I), comprises at least 97 wt.% of at least one calcium compound comprising calcium oxide, calcium hydroxide, and calcium carbonate, in the dry state, where: calcium sulfate does not exceed, in the dry state, 3 wt.% of (I); and (I) comprises less than or equal to 0.7 ppm by weight of boron with respect to calcium content and less than or equal to 4.2 ppm by weight of phosphorus with respect to calcium content.    USE - (I) is useful in pharmaceutical, food and solar cell industry and for removing boron and/or phosphorus from molten silicon for the production of solar cells (all claimed).    ADVANTAGE - The process: provides highly pure calcium carbonate or calcium oxide; and reduces co-precipitation of boron and phosphorus. The process parameters can be easily determined from the initial concentration of each reactant, without having to consider effective concentrations at any or all time during combination of the reactants.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a process for producing (I) comprising: forming a united solution containing a carbonate and calcium chloride by bringing together a first solution containing calcium chloride and a second solution containing a carbonate; precipitating calcium carbonate from the united solution containing the carbonate and the calcium chloride at 35-100 degrees C; separating the precipitated calcium carbonate from the mother liquor; optionally rinsing the precipitated calcium carbonate; and optionally drying the precipitated calcium carbonate, where: the first solution has a calcium concentration of X mol/l, the second solution has a carbonate concentration of Y mol/l (where X is comprised of 0.1-1.2 and Y is comprised of 0.1-2.5, such that X x Y less than or equal to 0.7); and the united solution has a boron content of below or equal to 10 ppm by weight with respect to calcium content and a phosphorus content of below or equal to 4.2 ppm by weight with respect to calcium content.    DESCRIPTION OF DRAWING(S) - The figure shows flow diagram of the production of calcium oxide from the liquors intervening in the ammonia-soda process.