The Use of Sewage Sludge in China’s Cement Industry

In times of dwindling resources, the rising prices for oil, coal and natural gas lead the industry to use alternative fuels, especially energy-intensive industries are seeking possibilities to integrate such fuels in their processes. The innovative Putzmeister (Germany) technology supports the cement industry in receiving and conveying alternative fuels.

Besides sewage sludge, other materials with high calorific value such as tar, paint sludge, slaughtering and food waste can be used. It does not matter of there are any foreign bodies in the material since the Putzmeister’s S-tube technology can convey them with up to 2/3 of the pipeline’s diameter. The delivered alternative fuels should only be conveyed in reprocessed form with the Putzmeister High-Density Solids Pumps, meaning that the material should be pumpable.

When processing sewage sludge, the dewatered sludge will be pumped from the receiving silo, which is equipped with a pump and screw conveyor, through the delivery pipeline and into the cement kiln. The flow rate is proportional to the capacity of the cement kiln. Solids content of up 80% do not disturb the process.

Due to its large capacity, the cement kiln can now continuously be fed with sewage sludge, even on week-ends and bank holidays when no alternative fuels are being delivered. Various sludge types can be admitted in the cement factory and be mixed by the pump through a recirculation process. Closed pipelines also, ensure a clean and odourless system