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From the late 5000 BC to around 4000 BC, the two river basins, Caucasus, Iran, India Valley and other places entered the Red Copper Age. Around 3500 BC, people burned copper ore with fire, and found that mixing copper and tin would produce bronze alloy with better performance. Since then, mankind has taken a key step in the utilization of copper ore.
There are few pure copper ores in nature, and most of them exist in the form of azurite, malachite and chalcopyrite, accompanied by other metals such as tin. Although metallic copper will only melt at 1085℃, if tin exists in copper ore, its melting point can be reduced to 800℃ at least. This temperature is the temperature that firewood fuel can reach, and the carbon contained in firewood will reduce copper and tin in the ore. The bronze fluid formed by the combination of copper and tin will harden after being injected into the mold and cooled. Because copper contains tin, its hardness will be increased by two times, so bronze containers are stronger and more beautiful, and bronze weapons are sharper.
By 3000 BC, bronze smelting in the Middle East and India was mature. However, according to the mining technology at that time, copper and tin were still high-end luxury goods in short supply, and most of them were made into ritual vessels and advanced weapons of the aristocratic class, rather than tools for production and life. Copper has embarked on the road of evolution, and the ability of human beings to transform nature has also been improved, and the scope of activities has been further expanded. Human beings extracted metals from copper ores by smelting, mastered the real metallurgy, and marked the transition from the Stone Age to the Bronze Age.
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After the end of the Bronze Age, human civilization entered the industrial age and the information age, and copper has increasingly become one of the most important basic metals, widely used in electric power, electronics, energy and petrochemical, mechanical metallurgy, transportation, light industry and other fields, which is inseparable from the inherent characteristics of copper, such as excellent ductility, thermal conductivity, electrical conductivity, corrosion resistance, resistance to organic acids and alkali, etc.
The earliest copper mining site in China is located in Tonglu Mountain, daye city, Huangshi, Hubei. As can be seen from the name, this mountain is rich in copper. In fact, it is also rich in iron and is a copper-iron polymetallic deposit. Its mining time can be traced back to the early Xia Dynasty 4000 years ago. Most of the ancient minerals discovered now are in the contact zone between granodiorite porphyry and marble. The main minerals are malachite, chalcopyrite and native copper, and the grade of copper is between 5% and 8%. Although Tonglu Mountain is called a mountain, it has already been dug into a valley, but its mountain is not seen. At the same time, the surface is covered with ancient copper smelting slag with a thickness of several meters and a weight of about 400 thousand tons.
The mining history of Zhongtiao Mountain in Shanxi can be traced back to the Warring States Period, and it is still being mined. Yunnan Dongchuan copper mine is one of the most important sources of raw materials for coins and utensils in Qing Dynasty, and 70% of coins in Qing Dynasty were cast by Dongchuan copper. Tongling, Anhui Province is also named after the copper mine, and it is prosperous because of copper. The first copper industrial base in New China was built here. The first copper bath and the first copper ingot all came from Tongling.
China is the largest copper consumer in the world. At present, there are 9 copper planning zones and 22 copper mines or copper polymetallic protection zones in China. Among them, the Duo Long copper mine in Ali, Tibet is the first world-class super-large copper mine concentration area in China, which has not yet been developed.
The country with the largest copper reserves in the world is Chile. There are 26 super copper mines with more than 20 million tons in the world, 9 of which are located in Chile. The copper-rich zone in Chile was formed in Mesozoic and Cenozoic. About 200 million years ago, the South American continent drifted westward and the Atlantic Ocean slowly opened. As an integral part of the active continental margin in South America, the Pacific (Nazca) plate subducted eastward was continuously suppressed in northern Chile, so the subduction plate broke, leading to large-scale volcanic activity. The intrusion of ore-bearing magma leads to mineralization and alteration of surrounding rocks, resulting in large-scale copper mineralization. Copper ore bodies generally occur in intrusive rocks or contact zones with surrounding rocks, forming Andes porphyry copper deposits. This kind of copper mine has low grade but huge reserves, and its output accounts for more than 50% of the world's copper output. It is the most important deposit type.