High-pressure binderless compaction of waste paper to form useful fuel

High-pressure binderless compaction of five types of waste paper typically found in municipal solid waste (MSW) stream, including corrugated board, newsprint, office paper, commercial printing, and non-corrugated box board, were studied. A piston-and-mold (punch-and-die) process was used and compaction was performed under room temperature and at pressures ranging from 34 to 138 MPa. The waste papers were compacted into 49-mm-diameter logs both separately and in mixture under various moisture contents and pressures. The properties of the logs including compressive strength, abrasion resistance, impact resistance, and combustion characteristics were tested. It was found that the waste paper mixture with moisture content ranging from 5% to 20% can be easily compacted into logs of good quality under pressures above 70 MPa. When the pressure is above 100 MPa and the moisture content of the waste paper is lower than 10%, logs with dry densities greater than 1 g/cm3 can be produced. The optimum moisture content for making abrasion-resistant and impact-resistant logs with high compressive strength is in the neighborhood of 15%. Compaction pressure of around 70 MPa was found to be cost-effective for the production of good quality logs from waste paper. The logs made from the waste paper have a heating value equivalent to that of lignite fuels, and can be co-fired with coal in power plants.