History of Cu

As one of the hardware, Cu is one of the earliest metals discovered by humans and the first metal to be used by humans. The Cu beads made of natural Cu excavated by archaeologists in northern Iraq are estimated to be more than 10,000 years old. Cu is widely used in electrical, light industry, machinery manufacturing, construction industry, transportation and other fields. As far as my country is concerned, Cu is second only to aluminum in the consumption of non-ferrous metal materials. At present, the smelting methods for producing electrolytic Cu in the world are mainly divided into two categories: pyrometallurgy and hydrometallurgy. At present, more than 80% of the refined Cu output is produced by pyrometallurgy, and the refined Cu produced by hydrometallurgy accounts for about 20%.

Cu is a prehistoric metal that was discovered and used by humans as early as primitive society. With the emergence of Cu, the Stone Age died out and humans gradually entered the Bronze Age.

In 1865, Europe invented Cu electrolytic refining, which was of great significance to the advancement of Cu smelting technology.

Wet Cu originated in my country and was called "Cu leaching with gall water" in ancient times. In the Tang and Song dynasties, it was mainly concentrated in Qianshan, Jiangxi, Dexing and Lingshui, Guangdong, with an annual output of nearly 2,000 tons. The ancient mines in Tongling were larger in scale and had a longer time span. From the Shang and Zhou Dynasties to the Tang and Song Dynasties, it has always been the center of Cu mining and smelting. The wet smelting process mainly includes four steps: leaching, extraction, stripping, and metal preparation (electrolysis or replacement). Oxidized ores can be leached directly, low-grade oxidized ores are heap leached, and rich ores are leached by Cao. Sulfide ores generally need to be roasted before leaching, or they can be leached directly under high pressure. Commonly used solvents in the leaching process include sulfuric acid, an, ferric sulfate solution, etc.

The pyrometallurgical smelting process mainly includes four main steps: matte smelting, Cu matte (matte) blowing, crude Cu pyrometallurgical refining, and anode Cu electrolytic refining.

Sulfur smelting (Cu concentrate - matte): mainly uses Cu concentrate to make matte smelting, the purpose is to oxidize part of the iron in the Cu concentrate, remove it by slag, and produce matte with higher Cu content.

Matte blowing (matte - blister Cu): further oxidize matte and remove iron and sulfur in matte by slag making to produce blister Cu.

Fire refining (blister Cu - anode Cu): blister Cu is further removed by oxidation and slag making to produce anode Cu.

Electrolytic refining (anode Cu - cathode Cu): by introducing direct current, anode Cu dissolves, pure Cu is precipitated at the cathode, and impurities enter the anode mud or electrolyte, thereby achieving the separation of Cu and impurities and producing cathode Cu.

Fire smelting includes flash smelting, molten pool smelting, and recycled Cu smelting. Among them, flash smelting includes three types: Inco flash furnace of International Nickel Company, Outokumpu flash furnace and vortex top blowing smelting (ConTop). Flash smelting is a smelting method that makes full use of the huge active surface of finely ground materials to strengthen the smelting reaction process. After the concentrate is deeply dried, it is sprayed into the reaction tower with oxygen-enriched air together with the dried flux. The concentrate particles are suspended in the space for 1-3 seconds, and the sulfide minerals are rapidly oxidized with the high-temperature oxidizing airflow, and a large amount of heat is released to complete the smelting reaction, that is, the matte making process. The reaction products fall into the sedimentation tank of the flash furnace for sedimentation, so that the Cu matte and slag are further separated. This method is mainly used for matte smelting of sulfide ores such as Cu and nickel.

Flash smelting began production in the late 1950s and has been promoted and applied in more than 40 enterprises. Because of continuous improvement, it has made remarkable achievements in energy conservation and environmental protection. This process technology has the advantages of large production capacity, low energy consumption, and less pollution. The maximum Cu production capacity of a single system can reach more than 400,000 t/a, which is suitable for factories with a scale of more than 200,000 t/a. However, the raw materials are required to be deeply dried to a moisture content of less than 0.3%, the concentrate particle size is less than 1mm, and the impurity lead and zinc in the raw materials should not be higher than 6%. The disadvantages of the process are complex equipment, high smoke and dust rate, and high Cu content in the slag, which requires depletion treatment.

Molten pool smelting includes Teniente Cu smelting process, Mitsubishi process, Osmet process, Vanyukov Cu smelting process, Isa smelting process, Noranda process, top-blown rotary converter process (TBRC), Baiyin Cu smelting process, Shuikoushan Cu smelting process and Dongying bottom-blown oxygen-enriched smelting process. Molten pool smelting is to add fine sulfide concentrate to the melt while blowing air or industrial oxygen into the melt, and strengthen smelting in the violently stirred molten pool. Because the blast presses bubbles into the molten pool, when the bubbles rise through the molten pool, it causes the "melt column" to move, which inputs a lot of power into the melt. Its furnace types are horizontal, vertical, rotary or fixed, and the blasting methods are side blowing, top blowing and bottom blowing.

Molten pool smelting has been used in industry since the 1970s. Due to the good heat and mass transfer effects during molten pool smelting, the metallurgical process can be greatly enhanced, achieving the purpose of improving equipment productivity and reducing energy consumption in the smelting process. Moreover, the requirements for furnace charge are not high. All types of concentrates, dry, wet, large particles, and powdered are applicable. The furnace volume is small, the heat loss is small, and the energy saving and environmental protection are relatively good. In particular, the smoke rate is significantly lower than that of flash smelting.

With the advancement of science and technology and the optimization of processes, people's demand for Cu is increasing, and the refining technology is getting better and better. Throughout the development of Cu, it has always played an important role in our lives.