Copper smelting and classification
smelting of copper
The copper ore mined from the copper ore is processed into copper concentrate or copper ore with higher copper content after beneficiation.
A. Electrolytic copper and refined copper
There are two types of copper used in industry: electrolytic copper (containing 99.9% to 99.95% copper) and refined copper (containing 99.0% to 99.7% copper). The former is used in the electrical industry for the manufacture of special alloys, metal wires and wires. The latter are used to make other alloys, copper tubes, copper plates, shafts, etc.
b. copper smelting process
The development of copper metallurgy technology has gone through a long process, but so far copper smelting is still dominated by fire-based smelting, and its output accounts for about 85% of the world's copper production. The copper smelting cost is greatly reduced.
Let's take a closer look at the two methods of copper smelting: pyrometallurgy and hydrometallurgy (SX-EX).
a. Fire copper smelting:
Cathode copper is produced by melting smelting and electrolytic refining, that is, electrolytic copper, which is generally suitable for high-grade copper sulfide ore. Pyro smelting is generally to first increase the raw ore containing a few percent or a few thousandths of copper to 20-30% through beneficiation, and use it as a copper concentrate to make it in a closed blast furnace, reverberatory furnace, electric furnace or flash furnace. Matte smelting, the resulting molten matte (matte) is then sent to a converter for blowing into blister copper, and then oxidized and refined to remove impurities in another reverberatory furnace, or cast into an anode plate for electrolysis, and the grade is as high as 99.9%. of electrolytic copper. The process is short and adaptable, and the recovery rate of copper can reach 95%. However, because the sulfur in the ore is discharged as sulfur dioxide waste gas in the two stages of matte making and blowing, it is not easy to recover, and it is easy to cause pollution. In recent years, molten pool smelting such as silver method and Nolanda method and Japan's Mitsubishi method have emerged, and pyrometallurgy has gradually developed towards continuous and automated development.
In addition to copper concentrate, scrap copper is also the main raw material for refining copper, including old scrap copper and new scrap copper. Old scrap copper comes from old equipment and machines, abandoned buildings and underground pipes; new scrap copper comes from processing plants and discarded Copper scraps (the output ratio of copper materials is about 50%), generally the supply of scrap copper is relatively stable, and scrap copper can be divided into: bare copper (grade above 90%); yellow copper (wire); (old motors, circuit boards); copper produced from scrap copper and other similar materials, also known as recycled copper.
b. Hydrometallurgical copper smelting:
A boat is suitable for low-grade copper oxide, and the refined copper produced is electro-deposited copper. Modern wet smelting methods include sulfated roasting-leaching-electrowinning, leaching-extracting-electrowinning, bacterial leaching, etc., which are suitable for heap leaching and tank leaching of low-grade complex ores, copper oxide ores, and copper-containing waste ores. ground leaching. Hydrometallurgical smelting technology is gradually being promoted, and it is expected to reach 20% of the total output by the end of this century. The introduction of hydrometallurgy has greatly reduced the smelting cost of copper.
The process flow chart is as follows: Among them, copper extraction (the process of copper entering the organic layer from the water layer) and back extraction (the process of copper entering the water layer from the organic layer) are important technological means of modern copper hydrometallurgy.
The two processes of fire method and wet method have the following characteristics:
(1) The smelting equipment of the latter is simpler, but the impurity content is higher, which is a beneficial supplement to the former.
(2) The latter has limitations and is subject to the grade and type of ore.
(3) The cost of the former is higher than that of the latter.
It can be seen that the hydrometallurgical smelting technology has considerable advantages, but its scope of application is limited, and not all copper ore smelting can use this process. However, through technological improvements, more and more countries, including the United States, Chile, Canada, Australia, Mexico and Peru, have applied this process to more copper smelting in recent years. The improvement of hydrometallurgy technology and the promotion of its application have reduced the production cost of copper, improved the capacity of copper mines, and increased the supply of social resources in the short term, resulting in a relative surplus of the total social supply, which has a pulling effect on prices.
Zhang Mei, a researcher at the Information Center of the Ministry of Land and Resources, said at the "7th China Nonferrous Metals Industry Chain Development Forum" held in Beijing from April 15th to 20th that the reserves of copper resources identified in my country will continue to increase significantly in the next five years.