FBC conversion of deinking residue to produce valuable cement products

Dutch papermills annually produce 300,000 tons deinking residue. Landfilling these residues encounters increased (governmental) disapproval. High municipal waste incineration costs will jeopardize the Dutch papermills competitive international position. Four Dutch papermills joined in CDEM Holland BV and developed a new and patented process that converts deinking residue into a high-valuable cement product using fluidized bed technology. The process has lower costs and is greener than its current alternatives. Deinking residues contain valuable minerals such as highly dispersed china clay and chalk. In the CDEM process, the china clay is dehydrated, and the chalk is partially calcined. These conversions produce a mineral product with cement-like properties. Please notice that the product is not a filler, it's cement in itself. Moreover, the product can be used as a specialty additive to increase ordinary Portland cement properties such as color and hardening. The mineral conversions require a very precise control of process conditions such as temperature, residence time, and gas-phase composition. A fluidized bed installation is used under different and very strictly controlled process-conditions, compared to normal FBC incineration. The organic fraction of the residue is incinerated, producing energy for the process and allowing for additional energy production. The throughput is relatively high (over 1,000 kg/m{sup 2}/hour); thus a small unit can convert large quantities of deinking residue. Emissions to air are low; the stringent Dutch legislation can be met without additional investments in flue-gas cleanup technology. Emissions to water are absent. The CDEM process has been developed and demonstrated using the fluidized-bed facilities of the Twente University at a 50--100 kg/hr bench-scale and a 250--500 kg/hr pilot-plant-scale. Over 100,000 kg of deinking residue has been processed. The cement product made during these trials has demonstrated its quality in various semi-commercial scale applications. Preparations to have a full-commercial-scale installation of 225,000 US ton/annum capacity running in the year 2000 are in full progress.