Background technology
Now, the China's economic high speed development, modernization construction still is rigid state to the demand of iron and steel.Blast furnace ironmaking is through the main flow technology that develops into the world of centuries, yet its technical process is long, investment is big, environmental pollution is serious, flexibility of operation is poor, to the feed stock for blast furnace poor selectivity, particularly the high energy consumption of the shortage of coking coal resource and blast furnace system has hindered further developing of blast furnace ironmaking.Nowadays, the fast development of non-blast furnace ironmaking technology, indivedual technology have reached its maturity and progressively industrialization.
In China's iron ore reserves, poor iron ore accounts for 98.1% of total reserves.Blast furnace also than higher, makes the many poor iron ores of China can not be used for normal smelting to the requirement of iron ore.Yet current international iron ore price rising all the way, particularly steel association fails in negotiation with three big mines in 2010, makes that the existence of Iron and Steel Enterprises in China is difficult more, so adopt the existing a large amount of poor iron ores of new smelting technology exploitation China extremely urgent.
China's iron ore deposit is widely distributed, and genetic type is various, and lean ore is many, and rich ore is few, and the symbiosis component is many in the ferruginous deposits.In identified 1834 place's iron ores, total proven reserve are 531.4 hundred million tons, and retained reserve is 501.2 hundred million tons, and wherein the retained reserve of high-phosphorus iron ore is 74.5 hundred million tons, accounts for 14.86% of the total retained reserve of national iron ore.The high-phosphorus iron ore that I cross mainly is distributed in the areas such as the Inner Mongol in Yunnan, Sichuan, Hubei, Hunan, Anhui, Jiangsu and the North China of the Yangtze valley, it distributes extensively, reserves are big, but its mineral composition complexity, phosphorus ore thing disseminated grain size is tiny, relation is complicated between phosphorus ore thing and the iron mineral, connecting forces is big, belongs to refractory ore.For a long time, make domestic existing a large amount of iron ore deposits not to be effectively used, cause some mine to stop exploitation because of phosphorous height owing to not developing the ideal method for reducing phosphorus.Adopt oxygen-enriched top blowing melting and reducing technology to smelt high-phosphorus iron ore and had effect preferably by the test checking.Can utilize the characteristics dephosphorization that strong oxidizing property atmosphere in the fusion reducing furnace and phosphorous oxides can stable existence in slag, thereby reach desirable metallurgical effect.
Summary of the invention
The present invention arises at the historic moment under the environment that this iron ore deposit goes from bad to worse, and is used for solving blast furnace technology energy consumption height, pollutes the problem big, that thermo-efficiency is low and China's poor iron ore of big reserves is difficult to smelt at blast furnace.This technology is simple to ingredient requirement, do not need coking, sintering, make operations such as ball, and investment construction, running cost is low, have fewer environmental impacts.
The objective of the invention is to adopt oxygen-enriched top blowing melting and reducing high-phosphorus iron ore to produce low-phosphorous molten iron.Enter fusion reducing furnace as carrier gas winding-up furnace charge from the furnace side with nitrogen, can add strong mixing, improve reacting dynamics condition.Simultaneously furnace gas is carried out dedusting, secondary combustion and exhaust heat recovery power generation.The invention of this technology not only can directly utilize common coal dust as the smelting reducing agent, and can effectively utilize the waste heat and the chemical energy of high-temperature furnace gas, and is more perfect aspect energy-saving and emission-reduction.
For realizing purpose of the present invention, by the following technical solutions: a kind of method of utilizing oxygen-enriched top blowing melting and reducing high-phosphorus iron ore to produce low-phosphorous molten iron is characterized in that containing following processing step: with furnace charge high-phosphorus iron ore, rhombspar, lime with go back the raw coal fragmentation; Scope according to basicity R is 1.0~2.0, in join carbon ratio C/O scope be 0.9~1.3 processing parameter proportioning mixing, preheating; Enter fusion reducing furnace as carrier gas winding-up furnace charge from the furnace side by nitrogen; Under the condition of oxygen-enriched top blowing, produce the relatively low molten iron of phosphorus content; Its molten iron and slag are then regularly emitted by iron notch and slag-drip opening respectively; High-temperature flue gas is by dedusting, secondary combustion; Utilize its cogeneration then, and the molten iron of coming out of the stove is carried out extra furnace dephosphorization and desulfurization.
Described furnace size≤30mm.
The expression formula of basicity R is:
Also the add-on of raw coal is m (coal):
In the following formula: the quality of m (x)-x material;
ω
y(z)-z in the massfraction of y;
K-conducts heat different and coefficient that produce at fusion reducing furnace, and coal dust is made reductive agent in fusion reducing furnace, also be heat-generating agent simultaneously.
The melting and reducing Control for Kiln Temperature is at 1350~1550 ℃, and the model and the fusion reducing furnace model of the oxygen rifle of its oxygen-enriched top blowing, heat exchanger, fly-ash separator, gas compressor are complementary.
The processing step of invention is: with furnace charge high-phosphorus iron ore, rhombspar, lime with go back the raw coal fragmentation; According to processing parameter proportioning mixing, preheating; Enter fusion reducing furnace as carrier gas winding-up furnace charge from the furnace side by nitrogen.Produce the relatively low molten iron of phosphorus content under the condition of oxygen-enriched top blowing, its molten iron and slag are then regularly emitted by iron notch and slag-drip opening respectively.High-temperature flue gas utilizes its cogeneration then by dedusting, secondary combustion., sulphur steel low-phosphorous for obtaining, molten iron carries out extra furnace dephosphorization and desulfurization to coming out of the stove.
Concrete processing parameter in the above-mentioned processing step of the present invention is: (1). the granularity of furnace charge fragmentation is≤30mm; (2). the scope of basicity R is: 1.0~2.0; (3). in join carbon ratio C/O scope be: 0.9~1.3; (4) the Reaktionsofen temperature control is at 1350 ℃~1550 ℃; (4). the speed visual fusion of the concentration of oxygen enrichment, pressure and winding-up furnace charge melt the model of reduction furnace and join the ore deposit than and decide.
Technical process of the present invention is as follows:
After the fusion reducing furnace warm start, the preheating furnace charge jetted as carrier gas from the side by nitrogen to be entered in the fusion reducing furnace, and control oxygen rifle is a reasonable altitudes, begins to advertise oxygen enrichment.Oxygen enrichment combustion-supporting down, coal dust heat supply melting batch reduces high-phosphorus iron ore simultaneously.In fusion reducing furnace, the slag blanket below is the reduction zone, is the zone of coal dust reduction high-phosphorus iron ore; The oxidation zone that cause for the top blast oxygen enrichment slag blanket top, inflammable gas secondary combustion in the combustion-supporting lower furnace chamber of oxygen enrichment, the slag blanket and the iron that send the fusion reducing furnace bottom with radiation and heat conducting mode to are bathed, and keep temperature of reaction.
In entire reaction course, the C in the coal dust is not only as reductive agent, simultaneously also as heat-generating agent.Wherein provide the reaction of heat to mainly contain:
2C+O
2=2CO
CO+O
2=CO
2
2H
2+O
2=2H
2O
High-phosphorus iron ore at high temperature melts and is reduced, and the reaction that kakoxene is reduced in the reduction zone, bottom mainly contains:
3Fe
2O
3+CO=2Fe
3O
4+CO
2
Fe
3O
4+CO=3FeO+CO
2
FeO+CO=Fe+CO
2
3Fe
2O
3+H
2=2Fe
3O
4+H
2O
Fe
3O
4+H
2=3FeO+H
2O
FeO+H
2=Fe+H
2O
6Fe
2O
3+C=4Fe
3O
4+CO
2
2Fe
3O
4+C=6FeO+CO
2
2FeO+C=Fe+CO
2
The reaction of phosphorus in slag iron has:
2Ca
3(PO
4)
2+3SiO
2=3Ca
2SiO
4+2P
2O
5
2P
2O
5+10C=4P+10CO
4P+5O
2=2P
2O
5
2[P]+5(FeO)=(P
2O
5)+5Fe
(P
2O
5)+3(FeO)=(3FeO·P
2O
5)
(3FeO·P
2O
5)+3(CaO)=(3CaO·P
2O
5)+3(FeO)
In addition, in reaction process, the generation that furnace charge is gone into gases such as CO in winding-up that stove carries out and the slag blanket will cause the molten bath strong disturbance, increases slag iron contact area and strengthens secondary combustion thermal conduction, improves the reacting dynamics condition in the fusion reducing furnace greatly.The molten iron that reduction draws is in the bottom, molten bath, and phosphorus then forms stable compound and is enriched in the slag, regularly discharges molten iron, skims.Carry out dedusting, secondary combustion and exhaust heat recovery power generation to going out kiln gas.The product of, sulphur steel low-phosphorous for obtaining can carry out extra furnace dephosphorization and desulfurization to the molten iron of coming out of the stove.
Beneficial effect of the present invention:
Adopting oxygen-enriched top blowing melting and reducing technology to smelt high-phosphorus iron ore has the following advantages:
1) this technology is used for solving blast furnace technology energy consumption height, pollutes the problem big, that thermo-efficiency is low and China's poor iron ore of big reserves is difficult to smelt at blast furnace, and this technique process is simple, does not need coking, sintering to make operations such as ball, pollutes and lacks, and cost is low.Directly utilize common coal dust, fine ore to get final product, more energy-conservation.
2) utilize phosphorus oxygen affinity height with and compound can the characteristics of stable existence in slag, the oxygen enrichment of top blast drives phosphorus enrichment in slag, thus produce the relatively low molten iron of phosphorus content., sulphur steel low-phosphorous for obtaining in subsequent handling, even ultralow phosphorus, sulphur steel can carry out further extra furnace dephosphorization and desulfurization to the molten iron of coming out of the stove.
3) carry out dedusting, secondary combustion and exhaust heat recovery power generation to going out kiln gas, effectively utilize fume afterheat and chemical energy thereof.
4) this technology invention will help developing a large amount of high-phosphorus iron ore resources that store of China, strengthen the international competitiveness of China Steel enterprise.Simultaneously can be so that Iron and Steel Enterprises in China is broken away from continuing to chase after and rise the dependence in three big mines, the world and international iron ore price.
Embodiment
A kind of basicity expression formula of utilizing oxygen-enriched top blowing melting and reducing high-phosphorus iron ore to produce the method for low-phosphorous molten iron of the present invention is:
The R scope is 1.0~2.0.
Also the add-on of raw coal is m (coal):
The quality of m (x)-x material;
ω
y(z)-z in the massfraction of y;
K-conducts heat different and coefficient that produce at fusion reducing furnace, and coal dust is made reductive agent in fusion reducing furnace, also be heat-generating agent simultaneously.
The C/O scope is 0.9~1.3.
The melting and reducing Control for Kiln Temperature is at 1350~1550 ℃, and model such as the oxygen rifle of its oxygen-enriched top blowing, heat exchanger, fly-ash separator, gas compressor and fusion reducing furnace model are complementary.
Embodiment 1 is with Huimin iron ore (TFe (%)=49.01, FeO (%)=1.36, SiO
2(%)=18.99, Al
2O
3(%)=5.81, MgO (%)=0.23, CaO (%)=0.36, TiO
2(%)=0.28, S (%)=0.038, P (%)=0.90), flux and coal (C (%)=76.43, ash content (%)=15.29, fugitive constituent (%)=7.78, CaO (%)=1.59, SiO
2(%)=7.80, S (%)=0.35, powder fragmentation P (%)=0.050) (≤30mm), according to basicity is 1.1, join carbon ratio C/O and be 1.1 processing parameter proportioning mixing, enter fusion reducing furnace by the furnace side winding-up, Control for Kiln Temperature is at 1450 ℃, the molten iron result who draws under the condition of oxygen-enriched top blowing: the rate of recovery of iron reaches about 86.8%, and phosphorus content is 0.32% in the pig iron, sulphur content 0.1645%, because its sulphur phosphorus content is still higher, so after molten iron is come out of the stove, utilize all the other oxidizing atmospheres to continue extra furnace dephosphorization, also need in addition it is carried out secondary desulfurization, and then deliver to steelshop.The model and the fusion reducing furnace model of oxygen enrichment and material preheater, fly-ash separator and gas compressor etc. are complementary.
Embodiment 2 above-mentioned raw materials are identical, according to basicity is 1.1, join carbon ratio C/O and be 1.1 processing parameter proportioning mixing, enter fusion reducing furnace by the furnace side winding-up, Control for Kiln Temperature is at 1400 ℃, and the molten iron result who draws under the condition of oxygen-enriched top blowing: the rate of recovery of iron reaches about 84.3%, phosphorus content is 0.23% in the pig iron, whether sulphur content 0.07% carries out extra furnace dephosphorization and desulfurization according to the requirement decision to molten iron, delivers to steelshop then.