Cast iron is created inside a furnace stoked with alternate levels of coking iron then poured into molds. Once the iron cools off, the sand is cleaned off. The Chinese have been the first to implement cast iron[1] within the 6th century AD working with it as assistance for pagodas https://www.finduslocal.com/local-business/california/los-angeles/naddours-custom-metalworks_1525-e-edinger-ave-santa-ana-ca-92705/