The paper presents the production technique of anorthite-based building ceramics using semidry pressing of the powder based on sintering of the raw mixture consisting of low-melting clay and blast furnace sludge (BFS) in different proportions. The fabricated ceramic specimens are sintered at 1050 °C. The raw mixture properties are studied to increase the anorthite phase content in ceramic specimens. Investigations of physical and mechanical properties of ceramic specimens show that the addition of BFS to the mixture composition provides the compressive strength of the obtained specimens up to 48.8 MPa, which is 25% higher than that of the reference specimen. The higher compressive strength is explained by the formation of the anorthite phase, which is proven by XRD investigation. According to the differential thermal analysis of the obtained specimens, exo-effect occurs at 1050 °C sintering, which is typical for the anorthite phase formation.