Metallurgical process of extracting metals or their compounds from ores at high temperature. This process is also called dry metallurgy because there is no aqueous solution. The technological process of pyrometallurgy is generally divided into three steps: ore preparation, smelting and refining. (1) Ore preparation. Fine-grained concentrate obtained by mineral processing is not easy to be directly added into blast furnace (or ironmaking blast furnace). Metallurgical flux (a substance that can react with gangue oxide and harmful impurity oxide contained in the ore) must be added first, then heated to below the melting point of the charge and sintered into blocks. Or adding adhesive to press and form; Or rolled into small balls and then sintered into small balls; Or add water and knead; And then put into a blast furnace for smelting. The main purpose of roasting sulfide concentrate in air is to remove sulfur and volatile impurities and convert them into metal oxides for reduction smelting. Sulfide is made into sulfate, and then wet leaching is carried out; Partial desulfurization makes it become matte composed of several sulfides in matte smelting. ② Smelting. This process forms slag and matte (the * * * melt of nonferrous heavy metal sulfide and iron sulfide) or molten metal containing a small amount of impurities, which is formed by melting gangue, flux and fuel ash. There are three smelting methods: reduction smelting, oxidation blowing and matte smelting. Reduction smelting is carried out in a blast furnace in a reducing atmosphere. In addition, there are rich ores, sintered blocks or pellets, and fluxes (limestone, quartzite, etc. ) is added into the furnace charge for slagging, and coke is added as a heating agent to generate high temperature and used as a reducing agent. Reducible iron ore is pig iron, reduced copper oxide ore is coarse copper, and reduced lead sulfide concentrate sinter is coarse lead. Oxidation blowing: It is carried out in an oxidizing atmosphere, such as blowing pig iron and oxygen with a converter, removing silicon, manganese, carbon and phosphorus from molten iron by oxidation, smelting into qualified molten steel and casting into steel ingots. Matte smelting: it is mainly used to treat copper sulfide ore or nickel sulfide ore, and is generally carried out in reverberatory furnace, submerged arc furnace or blast furnace. The added acidic Shi Ying flux forms slag with oxidized ferrous oxide and gangue, and a layer of matte is formed under the slag. In matte smelting, some iron and sulfur are oxidized, and more importantly, impurities are smelted to increase the content of main metals in matte and play a role in chemical enrichment. 3 refining. The metal containing a small amount of impurities obtained by smelting is further treated to improve its purity. For example, steelmaking is refining pig iron, degassing and deoxidation, removing non-metallic inclusions, or further desulfurization during steelmaking; Crude copper is oxidized and refined in a refining reverberatory furnace, and then cast into an anode for electrolytic refining; Arsenic, antimony, tin and iron contained in crude lead are removed by oxidation refining, and gold and silver contained in crude lead can be recovered by special methods such as Parker Justice. For high-purity metals, regional smelting and other methods can be used for further refining.
wet metallurgy
Shui Ye
Metallurgical process of extracting and separating metals from raw materials by chemical reactions (including oxidation, reduction, neutralization, hydrolysis and complexation) with a certain solvent. Also known as hydrometallurgy. Hydrometallurgy includes four main steps: ① Using solvent to transfer the useful components in raw materials into solution, that is, leaching. ② The leaching solution is separated from the residue, and the metallurgical solvent and metal ions entrained in the residue are recovered at the same time. ③ Ion exchange and solvent extraction techniques or other chemical precipitation methods are often used to purify and enrich leaching solution. (4) extracting metals or compounds from the purified liquid. Hydrometallurgy plays an important role in industries such as zinc, aluminum, copper and uranium. All alumina and uranium oxide, most zinc and some copper in the world are produced by hydrometallurgy. The advantage of hydrometallurgy is that it is suitable for extremely low-grade ores (gold and uranium) and similar metals (hafnium and zirconium) that are difficult to separate. Compared with pyrometallurgy, the material turnover is relatively simple, the comprehensive recovery degree of valuable metals in raw materials is high, which is beneficial to environmental protection and the production process is easier to realize continuity and automation.
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