Abstract: A process for sequestration of carbon dioxide comprising the following steps: (a) dispersing solid waste material comprising calcium oxide and a calcium-comprising mixed oxide in water to dissolve at least part of the calcium oxide and to form calcium oxide-depleted solid waste material in a calcium hydroxide solution; (b) separating the calcium hydroxide solution from the calcium oxide-depleted solid waste material; (c) converting the calcium hydroxide in the separated calcium hydroxide solution in precipitated calcium carbonate; and (d) contacting an aqueous slurry of the calcium oxide-depleted solid waste material with carbon dioxide for mineral carbonation of the carbon dioxide to form carbonated solid waste material.

Abstract: The present invention relates to a process for producing CaCO3 or MgCO3 from a feedstock comprising a Ca- or Mg-comprising mixed metal oxide, wherein: (a) an aqueous slurry of the feedstock is contacted with a C02 containing gas to form an aqueous solution of Ca(HCO3)2 or Mg(HCO3)2 and a solid Ca- or Mg-depleted feedstock; (b) part or all of the aqueous solution of Ca(HCO3)2 or Mg(HCO3)2 is separated from the solid Ca- or Mg-depleted feedstock; (c) CaCO3 or MgCO3 is precipitated from the separated aqueous solution of Ca(HCO3)2 or Mg(HCO3)2; and (d) the precipitated CaCO3 or MgCO3 is recovered as product. The invention further relates to a process for the production of an aqueous solution of Ca(HCO3)2 or Mg(HCO3)2.