Patent ID: 8742277

Claim:
A method for separating mineral impurities from calcium carbonate-containing rocks comprising the steps of: (a) comminuting and classifying calcium carbonate-containing rocks to obtain calcium carbonate particles having a particle size in the range of from 1 mm to 250 mm; and (b) introducing the calcium carbonate particles into an x-ray sorting device to remove mineral impurities from the calcium carbonate particles; wherein the x-ray sorting device comprises a means for transporting the calcium carbonate particles through the device, an x-ray source that emits radiation through at least two filter devices at different energy spectra to a flow of the calcium carbonate particles; at least one sensor means that measures two different x-ray outputs from the flow of the calcium carbonate particles at a detection area, a computer-controlled evaluating means that evaluates sensor signals resulting from the x-ray outputs at the detection area; and a separation means downstream of the detection area, that separates mineral impurities from the calcium carbonate particles.