Metallurgy has a long development history, from the Stone Age to the subsequent Bronze Age, and then to the large-scale development of modern iron and steel smelting. Metallurgical technology mainly includes pyrometallurgy, hydrometallurgy and electrometallurgy. With the successful application of physical chemistry in metallurgy, metallurgy has moved forward from process to science, leading to the major of metallurgical engineering in universities. - Hydraulic control valves for industrial use: Reliable in quality, superior in performance and with guaranteed efficiency. The valves can be customized according to customer’s requirements to meet the requirements of ordinary and special working conditions.