Calcium extraction from Estonian industrial ash bashed on ammonium solvents for production of precipitated calcium carbonateTamm, Kadriann; Viires, Regiina; Žuravljova, Anastassia; Otto, Kätlin; Kuusik, Rein, keemik; Uibu, MaiInternational IX Oil Shale Conference 2017 "Oil Shale Industry in Circular Economy" : 15th-16th November 2017, [Jõhvi], Ida-Viru County, Estonia : summary2017 / p. 28-29 : ill http://www.ester.ee/record=b4751282*est