Pyrometallurgy is a metallurgical process carried out under high temperature conditions.
Part or all of the minerals in the ore or concentrate undergo a series of physical and chemical changes at high temperatures to generate another form of compound or element, which are respectively enriched in gas, liquid or solid products to achieve the metal and gangue to be extracted The purpose of separation of other impurities. The heat energy required to realize the pyrometallurgical process is usually supplied by fuel combustion, but also by chemical reactions in the process. For example, the oxidation roasting and smelting of sulfide ore does not require fuel heating; the metal thermal reduction process is also self-contained Hot. Pyrometallurgy includes: drying, roasting, roasting, smelting, refining, distillation and other processes.
Hydrometallurgy is a metallurgical process carried out in solution. The temperature of hydrometallurgy is not high, generally lower than 100℃. In the high temperature and high pressure process in modern hydrometallurgy, the temperature is only about 200℃, and the temperature can reach 300℃ in rare cases. Hydrometallurgy includes: leaching, purification, metal preparation and other processes.
1. Leaching The ore or concentrate is treated with an appropriate solvent, so that the metal to be extracted enters the solution in a certain ion (cation or complex anion) form, while the gangue and other impurities are not dissolved. This process is called leaching. After leaching, it is cleared and filtered to obtain a metal (ion)-containing leaching solution and an insoluble residue (leaching residue) made of gangue minerals. For some difficult-to-leaching ores or concentrates, pre-treatment is often required before leaching, so that the extracted metals can be converted into certain compounds or salts that are easy to leaching. For example, sulfation roasting for conversion to soluble sulfate is a common preparation method.
1. Purification During the leaching process, some metal or non-metal impurities often enter the solution together with the extracted metal. The process of removing these impurities from the solution is called purification.
2. The process of extracting the metal from the purified liquid by substitution, reduction, electrowinning and other methods for preparing the metal.
Electrometallurgy is a method of extracting metal from electric energy. According to the effect of using electric energy, electrometallurgy is divided into electrothermal metallurgy and electrochemical metallurgy.
1. Electrothermal metallurgy is a method of smelting by converting electric energy into heat energy.
In the process of electrothermal metallurgy, according to the nature of its physical and chemical changes, it is not much different from the pyrometallurgical process. The main difference between the two is only the source of heat energy during smelting.
2. Electrochemical metallurgy (electrolysis and electrowinning) is the use of electrochemical reactions to precipitate metals from solutions or melts containing metal salts. The former is called solution electrolysis, such as the electrolytic refining of actinium and the electrowinning of zinc, which can be included in hydrometallurgy; the latter is called molten salt electrolysis, which not only uses the chemical effect of electrical energy, but also converts electrical energy into heat energy. Heating metal salts to make them melt, so they can also be included in the category of pyrometallurgy. The production process of extracting metals from ore or concentrate often includes both pyrotechnical and wet-process processes, even if the pyrotechnic process is the main process, such as the pyrometallurgical smelting of sulfide pot concentrates, and finally It also needs a wet electrolytic refining process; in the wet zinc smelting, the zinc sulfide concentrate also needs high-temperature oxidation roasting to pre-treat the raw materials.
Post time: Jan-05-2021