First off, bronze is an alloy, that is, a mix of different constituent metals. It consists of around 90 percent copper and 10 percent tin, although the tin can be replaced by other metals including arsenic. The ancients could melt and cast bronze and its constituent metals, tin and copper, however they were not able to cast iron. The process of extracting the metals from ore are roughly similar. Ore is roasted in fires and then put into a furnace to extract the metal. However this extraction process is different for each. Bronze's constituent metals were not found together, but both copper and tin were often found in ore with other metals such as lead. These metals all have different melting points, and thus could be extracted and separated.

The gradual process of learning how to do this was likely a result of firing pottery in different environments and noticing metal slag extracted from the earthen kilns or debris, although copper, lead, silver, and gold at least, were also found in elemental states in nature by the ancients and thus they had some previous experience with metalworking before the discovery of ore refinement. Alloys were discovered or developed somehow along the way and a primitive form of bronze, arsenical bronze, was developed. Arsenic was replaced by tin as it yields a better product and is not toxic. The fact that copper and tin were never found together, coupled with the relative scarcity of tin in the Mediterranean and Asia Minor spurred the development of overseas trade by the Phoenicians and early Greeks. These constituent metals were smelted near the mines and cast into ingots for transport to be refined or alloyed elsewhere. Sometimes the final work of making finished products happened in a separate location from this second stage as well.

Bronze was cast into ingots and then either recast into implements or worked by forging (i.e., in a solid state and not molten). The advantage of casting is that it requires less labor; the advantage of forging is that it requires less fuel, though it is also more difficult in addition to requiring more labor.

Iron was produced in a different manner. Again, the ore was roasted and placed in a furnace, but the furnaces used for iron did not melt it. The bloomery furnace was a vertical column into which "charges" of ore, charcoal, and often limestone or sand (for flux) were placed and fired with forced air introduced by tubes in the bottom. These bloomeries were often crudely made from clay mixed with straw and were sometimes discarded after even a single firing. The slag, or impurities such as silica and metals, in the ore and flux would melt and run down to the bottom while the iron particles, heated to welding temperatures but still solid, would sink and coagulate into a spongy mass called a bloom.

The slag would be removed from the base of the bloomery furnace and the bloom then removed and, while still at a high welding temperature, it would be gently beaten together, at first with wooden implements, to compact and weld the spongy mass into a more solid and regular shape. This compaction and welding would drive off some impurities and fracture what remained and incorporate it more homogeneously. The billet that resulted could then be divided with chisels and used to forge final products. The iron produced in this way is what is properly called 'wrought iron', essentially no longer produced today. It has practically zero carbon content, unlike modern steel, and has a high content of silica inclusions which give the product a grain not unlike the fibrous grain of wood.

I could probably add more but hopefully that answers your question. I'd be happy to provide sources if you like, but I've condensed a lot of different things together in this post from memory, so I'll leave it as-is for now.

Hi! Hopefully someone can drop by with some specific answers for you, but until then, you may be interested in checking out a few posts here

• FAQ section The transition from the Bronze Age to the Iron Age