The present disclosure is directed to an improved direct smelting process for improving the efficiency of energy/heat recovery from hot smelter offgas for the purpose of steam raising and power generation. In examples, the formation of alkali sulfate accretions in the temperature range 500-1000 C. are removed by introducing a mechanical sweep-cleaning system to an offgas duct of the smelter. The sweep-cleaning system comprises at least one central rotating shaft with chains, with each chain optionally having an accretion-removal member at its distal end. When rotated, the chains lift and the accretion-removal member sweeps the walls of the duct to remove the accretions.

A drain stopper assembly to reduce the growth of microbes within a drain is disclosed, including a support rod extending between a cap and a bottom portion. A pivot rod holder is positioned at an end of the bottom portion. A water separator is positioned at a top portion of the support rod, and a screen slidingly engaged between the support rod and the water separator. The drain stopper is removably insertable into a drain to extend between the drain opening and a waterline at the drain trap.

A drain stopper assembly to reduce the growth of microbes within a drain is disclosed, including a support rod extending between a cap and a bottom portion. A pivot rod holder is positioned at an end of the bottom portion. A water separator is positioned at a top portion of the support rod, and a screen slidingly engaged between the support rod and the water separator. The drain stopper is removably insertable into a drain to extend between the drain opening and a waterline at the drain trap.