Utilization of calcite-rich Green Liquor Dregs (GLD) by-products from pulp and paper industry: Cement clinker production and life cycle analysis

• Published in: Case Studies in Construction Materials Vol. 20; p. e02870
• Main Authors: Srivastava, Sumit, Moukannaa, Samira, Isteri, Visa, Ramteke, D.D., Perumal, Priyadharshini, Adesanya, Damilola, Kinnunen, Paivo, Ohenoja, Katja, Illikainen, Mirja
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2024; Elsevier
• Subjects: Analysis; Calcite; Cements; Clinker production; Environmental impact; Green liquor dreg; Green liquor dregs; Green Liquor Dregs (GLD); Life Cycle; Lime; Lime mud; Limestone; Limestone replacement; Paper and pulp; Paper and pulp industry; Paper and pulp waste; Production; Products; Pulp; Pulp and paper industry; Pulp Industry; Raw meal; Slake grit; Slaker grit; White Liquor Mud; Slaker grit; Clinker production; Limestone replacement; Paper and pulp waste; Green Liquor Dregs (GLD); Lime mud
• ISSN: 2214-5095; 2214-5095
• DOI: 10.1016/j.cscm.2024.e02870

The pulp and paper industry produces several calcite-rich by-products including Green Liquor Dregs (GLDs), lime mud, grits, sludges, etc. Presently, majority of these by-products are managed by landfilling. The GLD used in this study is mainly dominated by calcite (∼80 %) and Hydrotalcite like compounds (HTlc, ∼12 %). It is used to produced OPC clinkers by using them as 0 %, 5 %, 10 %, 15 %, and 20 % replacement of limestone used for clinker production. TGA-DSC analysis of the clinker raw meals up to 1350 ℃ indicates that increase in GLD leads to slight reduction in the decomposition temperature for the raw meals, and a slight change in the formation temperatures for C2S and C3S. The mineral phase compositions of all the clinkers are comparable with a slightly decreasing C3S and C2S with increasing GLD. Compared to the Bogue calculated compositions, C3S and C2S are slightly lower, while the C3A is significantly lower and C4AF is significantly higher. The environmental leaching of GLD and the clinkers are all within the limits set by EN-12457-2. The environmental impact of clinker production and effect of GLD is analyzed for cradle-to-gate scenario with system boundaries. This analysis shows that by using GLD as replacement for limestone can lower the impact on diversity as well as CO2 related to transportation can also be reduced. •Clinker produced by replacing 5-20 % limestone with GLD waste from paper industry.•Slightly reduced decomposition temperature of raw meal and clinker phase formation.•Environmental leaching of clinkers was found within limits of EN 12457-2.•Biodiversity conservation: timely in Nordics with limited limestone mining allowed.