2. The use of ferrosilicon
1) is used as deoxidizer and reducing agent in steelmaking.
In order to ensure the quality of steel, deoxidation must be carried out in the final stage of steelmaking. Because of the strong affinity between silicon and oxygen, a lot of heat will be released during the reaction, which is conducive to raising the temperature of molten steel.
Adding a certain amount of silicon into steel can significantly improve the strength, hardness and elasticity of steel, improve the magnetic permeability of steel and reduce the hysteresis loss of transformer steel.
2) Used as inoculant and nodulizer in foundry industry.
Cast iron is an important metal material in modern industry, which is cheaper than steel, easy to melt and smelt, and has two properties of casting and earthquake resistance. Adding a certain amount of ferrosilicon to cast iron can prevent the formation of carbides in iron and promote the precipitation and spheroidization of graphite, so ferrosilicon is an important inoculant and spheroidizing agent in the production of ductile iron.
3) Ferrosilicon is used as an additive of alloying elements.
As an alloying agent, ferrosilicon is widely used in low-alloy structural steel, alloy steel, spring steel, bearing steel, heat-resistant steel and electrical silicon steel.
4) As a reducing agent in magnesium metal smelting.
75# ferrosilicon is often used in the high temperature smelting process of metal magnesium by Pidgeon process. Magnesium in Cao. MgO is replaced, and the production of one ton of metallic magnesium consumes about 1. 1 ton of ferrosilicon, so ferrosilicon plays an important role in the production of metallic magnesium.
5) Other uses
In mineral processing industry, ground or atomized ferrosilicon powder is usually used as suspension phase.
It can be used as a coating for covered electrode in covered electrode manufacturing industry.
High-silicon ferrosilicon can be used to make silicone and other products in the chemical industry.
3. Ferrosilicon smelting
1) raw materials for ferrosilicon smelting
Ferrosilicon is made of silica, steel chips and coke by submerged arc furnace or electric furnace. However, due to the low temperature of electric furnace, the silicon content of the product is about 10-20%, so the blast furnace method is generally not used to smelt ferrosilicon now.
2) Ferrosilicon smelting process
When smelting ferrosilicon, submerged arc furnace is generally used for continuous operation. The so-called continuous operation method means that with the continuous reaction and melting of the burden after experiencing high temperature, the material level of the burden drops correspondingly, and at the same time, new burden is constantly replenished, so that the burden in the furnace is always full. According to the amount of alloy accumulated in the furnace, the alloy is discharged regularly. The whole smelting process is not divided into stages.
4. Ferrosilicon production
After decades of economic development, the ferrosilicon industry in China has formed a certain scale. It is estimated that the capacity of ferrosilicon has exceeded100000 tons, but the capacity utilization rate is low, and a considerable part of the capacity is idle. Main producing areas of ferrosilicon: Qinghai, Inner Mongolia, Ningxia, Gansu, Sichuan, Yunnan and other places. According to incomplete statistics, as of 2008, the production capacity of ferrosilicon in Qinghai has exceeded 800,000 tons, that in Ningxia120-1300,000 tons, that in Gansu1000,000 tons, that in Inner Mongolia is more than 4 million tons, and that in southwest China is about1000,000 tons.
5. Export situation of ferrosilicon
China is not only a big producer of ferrosilicon, but also a big exporter of ferrosilicon. China has a large number of ferrosilicon exports every year. The main importing countries are Japan, South Korea, the United States, Taiwan Province Province and other countries and regions. Among them, the total amount of ferrosilicon exported to Japan and South Korea accounts for about 50% of the total amount of ferrosilicon exported to China.
The customs codes of ferrosilicon are 72022 100 (silicon content is more than 55%) and 72022900 (silicon content is not more than 55%).
Before 2004, the export tax rebate rate of ferrosilicon was13%;
In June 2004, 65438+1 October1,the state reduced the export tax rebate rate of ferrosilicon to 8%;
In June 2005, 65438+1 October1,the state cancelled the export tax rebate rate of 8% for ferrosilicon;
In May 2005 1, the provisional tax rate for ferrosilicon export was raised to 5%;
June 2006 1 65438+1October1,and the provisional export tax rate of ferrosilicon was raised to10%;
On June 1 day, 2007, the provisional tax rate for ferrosilicon export was raised to15%;
In June 2008, 65438+1 October1,the export tariff of ferrosilicon was raised to 25%;
On June 2009, 65438+1 October1,the export tariff of ferrosilicon continued to maintain the tariff rate of 25%.
On June 20th 1 0, 1,1,the export tariff of ferrosilicon was maintained at the tariff rate of 25%. 1. definition of silicomanganese silicomanganese alloy is an alloy composed of manganese, silicon, iron, a small amount of carbon and other elements, and it is a kind of ferroalloy with wide application and large output.
2. Use of Si-Mn alloy
Silicon in Si-Mn alloy has strong affinity with manganese and oxygen. When Si-Mn alloy is used in steelmaking, the melting temperatures of deoxidized products MnSiO3 and MnSiO4 are 1270℃ and 1327℃ respectively, which have the advantages of low melting point, large particles, easy floating and good deoxidization effect.
3. Classification of Silicon and Manganese
Ferroalloy manufacturers usually refer to silicon-manganese alloy for steelmaking as commercial silicon-manganese alloy;
Silicon-manganese alloy for smelting low-carbon iron is called self-use silicon-manganese alloy;
Silicon-manganese alloy used for metal smelting is called high silicon-manganese alloy.
4. Silicon-manganese smelting
1) raw materials
Raw material ratio of silica, coke, manganese ore and manganese-rich slag, smelting power consumption is 4500-4800 kWh/t, imported manganese ore (Mn42-49%) 2 100-2500 kg domestic ore (Mn36%-30%) 2 100-2500 kg manganese-rich slag (.
In the process of smelting and heating the burden, the high valence oxides of manganese and iron in the burden are decomposed at high temperature or CO is reduced to low valence oxides in the burden area. At 1373- 1473K, the high-valent manganese oxide is gradually completely reduced to MnO, and all FeO is further reduced to Fe. With the increase of temperature, silicon is also reduced, and the carbon content in the alloy is further reduced. In the process of smelting Si-Mn alloy, in order to improve the reduction conditions of silicon, there must be enough silicon dioxide in the charge.
3) silicon and manganese specifications
According to China's national conditions, China Iron and Steel Industry Association suggested revising the national standards for silicon and manganese. The new national standard adjusted the manganese content and silicon content of three brands, namely FeMn64Si 16, FeMn64Si 18 and FeMn64Si23, and renamed the brands according to GB/T 7738.
4) Silicon-manganese downstream industry
iron and steel industry
With the rapid development of China's industry, China's steel output has increased year by year. 1987 China steel output was only 37 1.7 million tons. Twenty years later, the steel output in China has reached 489 million tons, increasing by 12.2 times. In recent years, the iron and steel industry in China has developed more rapidly. Although the global financial crisis that broke out in the second half of 2008 had a great impact on many industries in China, such as steel, ferroalloy, nonferrous metals, automobiles, real estate and so on, China's steel output still reached 568 million tons in 2009.
At present, China is still in a period of rapid urbanization and modernization. In the next 30 years, urbanization will still lead China's economic growth, and the urbanization rate will increase from 45% to 75%. Therefore, it is expected that the demand for steel in China will remain strong in the future.
5) Production of Silicon and Manganese
China's manganese ore resources are scarce and low-grade, and a considerable part of manganese ore needs to be imported. Domestically, there are abundant manganese ore resources in southwest China, so the main producing areas of silicon and manganese are distributed in Yunnan, Guizhou, Guangxi, Hunan and other places, while imported manganese ore is mostly used in the north, and Inner Mongolia is also the main producing area of silicon and manganese.
6) Import and export of silicon and manganese
The customs code of ferrosilicon is 72023000, and the current tariff is 20%. The export of silicomanganese alloy accounts for a large proportion in China's ferroalloy export, and China's silicomanganese alloy is mainly exported to Japan, South Korea, Canada, Taiwan Province Province, Hongkong and other countries and regions. Because most manganese ores need to be imported, the production costs of silicon and manganese are largely controlled by foreign miners. Characteristics of 1. magnesium
Magnesium is one of the most abundant light metal elements on the earth, and its specific gravity is 1.74g/cm3, which is only 2/3 of that of aluminum, 2/5 of that of titanium and 1/4 of that of steel. Magnesium alloy is 36% lighter than aluminum alloy, 73% lighter than zinc alloy and 77% lighter than steel.
2. The use of magnesium metal
1) Addition elements of aluminum alloy
Magnesium is the main alloying element in aluminum alloy, and the global annual demand is about 6.5438+0.6 million tons.
2) Magnesium sacrificial anode
As one of the effective methods to prevent metal corrosion, magnesium sacrificial anode is widely used in underground long-distance iron pipeline and oil storage tank.
3) magnesium alloy profile
Magnesium alloy profiles and pipes used to be mainly used in aerospace and other cutting-edge or national defense fields. In recent years, due to the improvement of production capacity and technical level of magnesium alloy, its production cost has been reduced to the level equivalent to that of aluminum alloy, which greatly stimulated its application in civil fields, such as bicycle frames, wheelchairs, rehabilitation medical equipment and fitness equipment.
4) Magnesium alloys for automobiles and motorcycles
In 2000, the world output of automobiles and motorcycles reached 27 million and 654.38 million respectively. If each car uses 30 kilograms of magnesium alloy and each motorcycle uses 5 kilograms of magnesium alloy, the annual consumption of magnesium in a single car will reach about 900 thousand tons, far exceeding the annual output of magnesium. As a further development goal in the future, the consumption of magnesium alloy per car and motorcycle can reach 100 and 15 kg. There will be a huge demand for magnesium alloy products.
5) the shell of electronic products
Magnesium alloy has excellent thin-wall formability, its die-casting thickness can reach 0.5mm- 1mm, and it maintains certain strength, stiffness and impact resistance, which is very beneficial to the requirements of ultra-thin, ultra-light and miniaturization of products. In addition, magnesium alloy shell can make products more luxurious and beautiful, which is incomparable to engineering plastics. The unit weight and size of magnesium alloy products in electronic information and instrumentation industry are not as good as those in automobile parts, but the quantity and coverage are large and the consumption is huge. Therefore, in recent years, the consumption of magnesium alloys in the electronic information industry has increased sharply, which has become another important factor driving the increase of global consumption.
3. Metal magnesium smelting
At present, there are two main methods for magnesium smelting:
1) Chlorinated molten salt electrolysis includes magnesium chloride production and magnesium electrolysis. The method can be divided into electrolysis of anhydrous magnesium chloride with magnesite as raw material and electrolysis of anhydrous magnesium chloride with seawater as raw material.
2) The thermal reduction method for producing magnesium oxide by calcining carbonate ore with ferrosilicon is called thermal reduction method.
4. Packaging and transportation of magnesium metal
Primary magnesium ingots are packed in metal trays made of materials or special dry wooden trays. After the surface is wrapped with integral plastic sheets, it is bound with steel belts (horizontally and vertically). The steel strip shall comply with the relevant provisions of YB/T025. Each bundle must be magnesium ingots of the same brand, with a net weight of 1000kg 50kg or 500kg 20kg. Primary magnesium ingots are transported in clean containers or vehicles equipped with rain-proof equipment. Protect products from moisture during loading and unloading.
5. Production of metallic magnesium
With the rapid development of economy, the magnesium metal industry in China has also made great progress. Shanxi, Shaanxi, Ningxia and Inner Mongolia have gradually formed the main producing areas of magnesium metal by virtue of their resource advantages.
As far as the production status of magnesium metal in China is concerned, a considerable part of magnesium metal is smelted by reduction method, and only a few magnesium metal factories are smelted by electrolysis method. Most foreign manufacturers of magnesium metal are electrolytic smelting, but due to the control of resources and environment, some magnesium metal has been put on the stage.