As an ancient metallurgical technology, both at home and abroad history for thousands of years. Human beings use stone tools and pottery to enter and use metal. This is a leap in human civilization. According to the history of metallurgy, about 30 century BC, humans began to use a large number of bronze, the era known as the "Bronze Age"; to the 13th century BC, iron is used in Egypt accounts for a certain percentage, which is generally considered It is the beginning of humanity entering the "iron age". Human beings are increasingly associated with metallic materials and their products. The tools and facilities used in people's daily life, production and other activities are inseparable from metallic materials and their products, that is to say, there is no human material without metal materials. civilization. The development of metallurgical technology in ancient China was earlier than in European countries, especially in mastering cast iron and heat treatment technology. As far as metal types are concerned, China has been able to extract seven common metals such as copper, iron, tin , lead , mercury , gold and silver on the occasion of the Spring and Autumn Period and the Warring States Period (7th century BC). However, due to the long-term persistence of metallurgical technology in the traditional way of operation or mastery, the development of metallurgical technology in the world has been very slow in the past thousand years. Modern metallurgy can be considered to have started in the 19th century, and metallurgy has been rapidly developed due to the influence of other disciplines. In particular, achievements in chemistry, physics, thermal energy, and engineering have led to continuous improvement in metallurgical production technology. For example, contents include not only traditional metallurgical process reduction and carbon oxide, and the use of electricity and begin producing an electric furnace capable of producing high temperatures and the atmosphere can be controlled, and emergence of a new method for molten salt electrolysis of aluminum and the electrolysis of aqueous solutions of non-ferrous metals, In the metallurgical process, the application of oxygen, the use of large-scale automated ironmaking blast furnace, oxygen top-blown converter steelmaking, vacuum metallurgy and flash smelting and other new technologies, metallurgical technology has entered a new stage of development. Extraction metallurgy belongs to the raw material industry, mainly involves the development and utilization of resources, including the extraction, separation, purification and production of various metals and their compounds from mineral resources, and the processing of metal or alloy materials with certain properties. Metals can be classified into ferrous metals, non-ferrous metals, rare metals, and precious metals. With the mass exploitation of mineral resources, mineral resources, some land Pat become exhausted, now we began to notice marine mineral resources, research and polymetallic manganese nodules from the ocean floor to extract and separate the valuable metals from seawater. At the same time, starting from sustainable development and ecological environmental protection, people are paying more and more attention to recycling useful metals from secondary renewable resources, so the objects and scope of metallurgy extraction are also expanding. The Brake Pads Adapted to Das Auto-Audi Audi Audi Front Brake Pad,Audi Brake Pad,Audi Disc Brake,Audi Auto Brake Ningxia Rossking Auto , https://www.rosskingauto.com