Heat and power production in Estonia is based on local low-grade oil shale, which is characterized by high content of mineral matter (60-70%) presented mainly by limestone and dolomite. The last circumstance allows near complete binding of SO2 in boilers operating according to CFB combustion technology and at extent of 70-80% in case of PF technology. Oil shale ash, consisting 10-30% of free lime, is hydro-transported and deposited in open air ash fields. At that large quantities (15-20 mil m3) of highly alkaline wastewaters (pH~12-13) circulate in the system. These waters are saturated with Ca2+-ions which are available for CaCO3 and CaSO4 precipitation during contacting with acidic SO2/CO2-containing flue gases. As another remarkable alternative, the ash can be served as Ca-source for producing precipitated calcium carbonate (PCC) which has a wide range of usage (as filler in paper, rubber and plastics industry). Laboratory experiments with ash, mainly by periodic processes are carried out in Laboratory of Inorganic Materials of Tallinn University of Technology (LIM TUT). In periodic apparatus these would run more slowly and the mass transfer processes are easily observed. The mechanism and kinetics of chemical reactions are independent of the type of apparatus but the main difficulty is to realize these processes in continuous mode of industrial scale which should be fast. The aim of the study is to work out reasoned scheme of continuous pilot-scale working devices also to give approximate estimation for realization of the processes in industrial scale. As a result, continuous processes for a) cleaning of flue gases from remaining SO2 based on ash suspension, b) diminishing of CO2 emissions and c) production of appropriate size (1-2 microns) PCC particles from the leaching water of ash are developed. The co-operation with Lappeenranta University of Technology is foreseen, especially in the field of ash leaching, washing and filtration.