Copper, Cement & Glass
Copper: Copper is one of the few metals that can occur in nature in a directly usable metallic form. This led to very early human use in several regions, from c. 8000 BC. Thousands of years later, it was the first metal to be smelted from sulfide ores, c. 5000 BC; the first metal to be cast into a shape in a mold, c. 4000 BC; and the first metal to be purposely alloyed with another metal, tin, to create bronze. Most copper is mined or extracted as copper sulfides from large open-pit mines.
Cement manufacturing is a complex process that begins with mining and then grinding raw materials that include limestone and clay, to a fine powder, called raw meal, which is then heated to a sintering temperature as high as 1450 °C in a cement kiln.
Glass: Glass production involves two main methods – the float glass process that produces sheet glass, and glassblowing that produces bottles and other containers. Batch processing is one of the initial steps of the glass-making process. The batch house simply houses the raw materials in large silos and holds anywhere from 1–5 days of material. The batch is fed into the furnace at a slow, controlled rate by the batch processing system. The furnaces operate at temperatures up to 1,575 °C (2,867 °F).