The difference between the modern industrial hydrometallurgy and pyrometallurgy
method also known as dry metallurgy, smelting the ore and the necessary additives with heated to high temperature in the furnace, melting into liquid, generate the chemical reaction, so as to separate the thick metal, then coarse metal refining. Using high temperature metal or its compounds extracted from ore metallurgical process. No solution to participate in this process, so it is also known as dry process of metallurgy. General component is the processes of pyrometallurgy ore preparation, smelting, refining 3 steps.
pyrometallurgy, mainly thermal reduction process, the ore heating cases, with some reductant reduction of metal, such as carbon, carbon monoxide.
hydrometallurgy, the main principle is to use a reducing strong elemental substitution out of a substance from a solution of metal, in which iron widely used replacement of copper in the copper sulfate solution.
the metallurgical process hydrometallurgy is to use aqueous solution of acid, alkali, salt, chemically extracted from ore required metal components, and then use the electrolytic aqueous solution, etc. Various methods for making metal. This method is mainly used in low standard, difficult to melt or micro powder ore. Now, with 75% of the world's zinc and cadmium is the roasting - Leach - Into the aqueous electrolysis legal system. This method has been mostly replaced the old method of zinc. Other metals such as nickel - is difficult to separate Cobalt, zirconium - Hafnium, tantalum - Niobium and rare earth metals are using hydrometallurgy technology such as solvent extraction or new methods such as ion exchange separation and achieved significant effect.
use a solvent, with the aid of a chemical reaction ( Including oxidation, reduction, neutralization, hydrolysis and complexation reaction) The extraction and separation, the raw material of the metal metallurgical process.
hydrometallurgy consists of four main steps: by solvent
(1) raw materials into useful ingredients in solution, the leaching.
(2) the leach solution and residue separation, at the same time will be entrained in residue solvent in metallurgy and metal ions.
(3) purification of leach solution and concentration, ion exchange and solvent extraction technology or other commonly used chemical precipitation method.
(4) or compound extracted from purifying liquid metal. In zinc hydrometallurgy, such as aluminum, copper, uranium industry occupies an important position, all of the alumina, uranium oxide in the world, most of the zinc and part of that is produced by wet method.
the advantage of modern industrial hydrometallurgy
the excellency of hydrometallurgy is of very low grade ore ( Gold, uranium) Applicability of similar metals ( Hafnium and zirconium) Difficult to separate the applicability of the situation; And compared with those of pyrometallurgy material flow is simple, high degree of comprehensive recycling valuable metals in raw material, is beneficial to environmental protection, and easier to realize continuous production process and automation.