The Pirdop CopperCopper Plant started constructionConstruction in 1955 and was commissioned in December 1958 in Pirdop, Srednogorie region, Bulgaria. From then on, the plant has continuously and significantly improved its smelterSmelter processes, working conditions, and operational practices. Outokumpu Flash SmeltingFlash smelting technologySmelting technology was adopted in 1987 with a nominal designDesign capacity of 50–60 tons of blendBlend per hour. Since then, the flash smelting furnaceFlash smelting furnace (FSF) capacity has increased four-fold, improving the plant’s performancePerformance. Many modifications and improvements were implemented on the FSF supporting facilities to remediate worn equipmentEquipment and allow increased FSF throughputThroughput. Currently, the primary copper smeltingPrimary copper smelting process in Aurubis BulgariaAurubis Bulgaria includes a FSF with a single jet burner with designDesign capacity of 240 t/h. The FSF is supported by concentrateConcentrate blending and drying units, PSC converters, twin casting wheels, two separate Sulfuric AcidSulfuric acid production lines, Electrorefinery (Tank house), and a SlagSlag FlotationFlotation Plant, the latter—unique for the Aurubis Group. This paper outlines the technological improvementsTechnological improvements carried out in the smelterSmelter and the sulfuric acidSulfuric acid production. These include higher safetySafety standards, technological upgrades, equipmentEquipment replacementReplacement, modernizationModernization and modification, and increased environmental protection, for a ten-year period (2014–2024). All these improvements significantly contributed to higher concentrateConcentrate throughputThroughput, equipmentEquipment life and plant availability.