The requirement that plants according to place steel-making goes to the purify of the quantity that contain carbon in cast iron formulary limits, make the content of other element decreases or the process that increases formulary scope. Say simply, it is opposite iron falls carbon, go the process of content of the sulfur phosphor, manganese that move silicon. This one process basically is process of a combustion, it is the oxygen that uses different source (the oxygen with oxygen, if air is medium oxygen, pure medium iron ore) come the element such as the carbon in ferric oxide water, silicon, manganese.
Steel-making principle is to use oxygen or ferric oxide to fall to take off the redundant carbon in cast iron and other foreign matter in high temperature divide gas or slag is medium.
Steel-making method can be divided commonly for converter steel-making, open-hearth furnace steel-making and electric stove steel-making. They describe as follows:
1. converter steel-making: The oxidant that uses in steelmaking process is oxygen. air inbreathe cast iron in, the impurity such as oxidation silicon and manganese. A large number of quantity of heat are emited in combustion process (1% silicon can make cast iron temperature elevatory 200 Celsius) , make furnace is achieved enough high temperature. Accordingly, converter steel-making does not need additional fuel.
Converter steel-making undertakes inside converter. Converter appearance resembles pear, wall has firebrick, fireside has a lot of alveolus (blast tuyere) , compress furnace of air therefrom inbreathe inside, also call side-blown converter. Above all, converter is in horizontal condition, inward ministry infuse the liquid state cast iron of 1300 Celsius, join the calx of certain amount, next inbreathe air, rotate converter makes his erect. Right now, surface of liquid state cast iron is acuteness reaction, iron, silicon, manganese (FeO, SiO2, MnO) be oxidized (FeO, SiO2, MnO, MnO) generation slag, molten iron, molten steel and slag are used at convection, make reaction diffuses whole the chamber of a stove or furnace. In a few minutes, should remain only in steel fluid a few when silicon and manganese, carbon begins oxidation, generation carbon monoxide (radiative) , make steel fluid boiling. Burn as a result of the carbon dioxide that spill over, mouth has a tremendous blaze. Finally, phosphor is oxidized, form phosphoric acid ferrous further. Phosphoric acid ferrous and calx reaction generate stable phosphoric acid calcium and vulcanization calcium, they become broken bits jointly.
Content of the phosphor in sulfur is reduced gradually, blaze drops, the Brown vapour of mouth occurrence Fe3O4, show steel already smelt. Answer to stop blowing instantly right now, move converter to horizontal position, molten steel is wrapped into steel inside, join deoxidizer to undertake deoxidization. Whole process needs 15 minutes only. If from air of the inbreathe in furnace, criterion it is low blow converter.
As the development of the technology that make oxygen, aerobic top-blown converter (call side-blown converter again) received wide application. Blowing of this kind of converter is high-pressured industry pure oxygen, reaction is more strong, can improve manufacturing efficiency and rolled steel quality further.
2. the 2nd pace. Open-hearth furnace steel-making (open-hearth furnace steel-making, also be called Martin method, when already passing now) : The oxidant that uses in open-hearth furnace steel-making enters the oxide in air and charging (scrap iron, useless steel, iron ore) . The quantity of heat that reaction place needs by aeriform fuel (blast furnace gas of gas, production) or liquid fuel (heavy oil) combustion is offerred.
The crucible of open-hearth furnace is the chamfer that makes by firebrick, roof is enclothing firebrick. Opening type furnace before there is opening of a feed a machine on the wall, charger from on makings mouth begins feed a machine. When smelt, close the door that firebrick causes. The two end of furnace have furnace head, every furnace head has two opening, with will guide fuel and sirocco, perhaps use guide the chamber of a stove or furnace inside gas.
The raw material that place of open-hearth furnace steel-making uses has useless steel, scrap iron, iron ore and dissolvent (limestone and calx) . In fusion in the begining, when the hot air that encounters an entrance below the temperature that is as high as 1800 Celsius, fuel apparently fuel burns. On the charging that quantity of heat goes to to fuse quickly from blaze move directly (the melting point of iron is 1535 Celsius, and the melting point of steel slightly low) . In the meantime, certain melt cast iron forms oxidation ferrous, the foreign matter silicon in cast iron and manganese oxidize by oxidation ferrous, form sound broken bits. Because the limestone inside furnace is overmuch, the impurity such as phosphor, sulfur forms phosphoric acid calcium and vulcanization calcium, form broken bits. Next, when the metal is boiling, carbon also is oxidized with producing carbon monoxide from inside melt metal.
When reaction swift end, join deoxidizer, blow broken bits regularly. When smelt is finished, whether does the class status that must check steel according to the analysis before furnace accord with a requirement (through analysing a method quickly, achievable a few minutes) . The cesium that steel-making uses flows into steel bag from taphole, flow into mould from steel bag next, form product or ingot casting.
To raise furnace temperature, answer to enrage body fuel in the warm-up inside regenerator.
Liquid state cast iron can be joined not only inside open-hearth furnace, still can join solid cast iron, scrap iron and the iron ore after clip is hurt. Additional, use air of 30% oxygen boosting to air in open-hearth furnace, metal of aerobic inbreathe melt, can improve manufacturing efficiency 80% , smelt time shortens 2-4 hour, save fuel, need not air of warm-up oxygen boosting.
3. Electric stove steel-making: Steel also can be in the electric stove that is heat source with electric energy smelt. Use electric stove steel-making producible high grade alloy steel. Electric stove sort is various, use the most extensive is electric arc furnace.
Get Price
WhatsApp