Pig Iron发表评论(0)编辑词条

Pig iron is the intermediate product of smelting iron ore with coke, usually with limestone as a flux. Pig iron has a very high carbon content, typically 3.5–4.5%, which makes it very brittle and not useful directly as a material except for limited applications.

The traditional shape of the molds used for these ingots was a branching structure formed in sand, with many individual ingots at right angles to a central channel or runner. Such a configuration is similar in appearance to a litter of piglets suckling on a sow. When the metal had cooled and hardened, the smaller ingots (the pigs) were simply broken from the much thinner runner (the sow), hence the name pig iron. As pig iron is intended for remelting, the uneven size of the ingots and inclusion of small amounts of sand was insignificant compared to the ease of casting and of handling.
The Chinese were making pig iron by the later Zhou Dynasty (1122–256 BC). In Europe, the process did not become common until the 14th century.

The vast majority of PIG IRON is produced and consumed within integrated steel mill complexes. In this context the term “pig iron” is something of a misnomer: within integrated steel mills, blast furnace iron - hot metal - is transferred directly to the steel plant in liquid form. The term “pig iron” arose from the old method of casting blast furnace iron into moulds arranged in sand beds such that they could be fed from a common runner. The group of moulds resembled a litter of sucking pigs, the ingots being called “pigs” and the runner the “sow.”     

MERCHANT PIG IRON is cold iron, cast into ingots and sold as ferrous feedstock for the steel and metal casting industries. It falls into the category of ferrous metallics, of which iron and steel scrap comprises by far the largest volume, others being direct reduced iron [DRI], hot briquetted iron [HBI] and various other “alternative iron” materials. Merchant pig iron is, by definition, produced by dedicated merchant plants all of whose production is sold to external customers. Some integrated steel mills produce blast furnace iron that is surplus to their internal requirements and this is also cast into ingots and sold as merchant pig iron.

Merchant pig iron comprises three main types: BASIC PIG IRON, used mainly in electric arc steelmaking, HAEMATITE PIG IRON [also known as FOUNDRY PIG IRON], used in mainly in the manufacture of grey iron castings in cupola furnaces, and NODULAR PIG IRON, used in the manufacture of ductile [also known as nodular or spheroidal graphite - SG] iron castings. Pig iron contains at least 92% Fe. Other constituents are typically:

  BASIC PIG IRON 3.5-4.5% carbon, <1.5% silicon, 0.5-1.0% manganese, <0.05% sulphur, <0.12% phosphorus 
  
  HAEMATITE PIG IRON 3.5-4.5% carbon, 1.5-3.5% silicon, 0.5-1.0% manganese, <0.05% sulphur, <0.12% phosphorus 
  
  NODULAR PIG IRON 3.5-4.5% carbon, <0.05% manganese, <0.05% sulphur, <0.05% phosphorus 

Most merchant pig iron is produced through the reduction of iron ore in blast furnaces, using either coke or charcoal as reductant and energy source. Pig iron, principally nodular pig iron, is also produced through the smelting of ilmenite in electric furnaces, as a by-product of titanium dioxide slag production. For more detail on the Blast Furnace and Ilmenite Smelting process, click on the links below.

生铁，是将铁矿石、焦炭、石灰石等原料投进高炉熔炼，由高炉直接炼得并在模中铸造出来的铁。生铁的成分中，碳的比例相当的高，约在2.5~4.5%左右(碳钢的含碳量为0.02~2.14%)，质地相当的脆，必须将其炼造成钢以后才能有较多的用途。
另一方面，亦有直接从生铁捶打的炊具，比用熟铁铸造的炊具更耐用。
铸铁按照断口颜色可分为白口生铁和灰口生铁：
• 灰口生铁：又称铸造生铁。含碳量较高，达到2.7％～4.0％，碳主要以石墨状态存在，断口呈灰色。凝固时收缩量小，硬度高，抗压强度高。是目前应用最广泛的铸铁。
• 白口生铁：又称炼钢生铁。含碳量，含硅量均较低，碳主要以渗碳体状态存在，断口呈白色。凝固时收缩量大，脆性大。