Cement grout obtd. from gas washing muds - uses lime and limestone added for washing and fly ash in the gas

摘要

The parent patent described removal and use of washing muds obtd. from washing off-gases with lime or limestone to remove sulphur oxides. The muds which contain sulphites and/or sulphites are dehydrated and treated with lime and/or fly ash to give cementitious compsns. comprising 30-90% solids including 0.25-70% alkaline earth sulphite, 0.25-70 wt % alkaline earth hydroxide and 10-99.5% fly ash. This mixt. was used for grouting or pointing of mortar layers on brick buildings. In this addition patent, the mud itself can provide part or all the alkaline earth hydroxide and/or the fly ash necessary to provide the stoichiometric excess of lime or limestone used in the washing and subsequently available for reaction. Similarly the fly ash need not be separated from the off gases before washing and this flay ash is then available to the reaction. The residual matl. has a pozzolanic activity equal to 10-99.5% of fly ash according to ASTM C 618. There is no need to separate the fly ash before operation and the lime needed may be incorporated at the washing stage.