This paper presents the results of a study on the effect of waste from the Kadamjai Antimony Plant (KSK) on the physical and mechanical properties of ceramic materials. Loams from various deposits in the Osh region and tailings from the flotation enrichment of antimony ores, containing quartz, calcite, and minor amounts of clay minerals, used as raw materials. The influence of KSK waste content (0–100%) on the plasticity, sensitivity coefficient, and drying behavior of raw mixtures, as well as on the density, water absorption, and strength of fired samples at 900–1000 °C, investigated. The results demonstrate that the addition of KSK waste reduces the sensitivity coefficient by a factor of 2–2.8, decreases air shrinkage, facilitates the formation of strengthening phases (mullite, anorthite), and increases compressive strength at the optimal firing temperature of 950 °C. These findings confirm the potential of KSK waste as a raw component in ceramic production, enabling the manufacture of products with enhanced performance characteristics while simultaneously mitigating environmental impacts.