CN1249350A

CN1249350A - Technology for directly reducing iron with coal base in pot furnace

Info

Publication number: CN1249350A
Application number: CN 98119030
Authority: CN
Inventors: 陈守明; 黄超; 彭黎; 杨景武; 魏盛远; 张志敏
Original assignee: Beijing Inst Of Metallurgical Equipment Ministry Of Metallurgical Industry (cn
Current assignee: Beijing Inst Of Metallurgical Equipment Ministry Of Metallurgical Industry (cn
Priority date: 1998-09-28
Filing date: 1998-09-28
Publication date: 2000-04-05
Anticipated expiration: 2018-09-28
Also published as: CN1067436C

Abstract

A technolog for directly reducing iron with coal base in pot furnace features that powdered iron concentrate and binder are used to make cooled agglomerated pelets, non-coked coal is used as reducing agent, both of them are loaded into pot furnace layer-by-layer or after mixed. After preheating, reducing and cooling procedures, sponge iron is made, and then is separated from cinder by dressing. The technology integrates smelting iron in blast furnace with coking in coke-oven, and has the advantages of high quality of sponge iron, high adaptability to raw materials and fuels, simple equipment and low cost.

Description

The production method of pot furnace coal-based direct reduction iron

The present invention relates to a kind of ferrous metallurgy technology, the coal-based method shaft furnace of especially a kind of usefulness with ferric oxide by the solid-state direct reducing process that is converted into iron.Its product claims direct-reduced iron, is called for short DRI, also is sponge iron.

At present, the direct-reduced iron production technique is a lot, divides by reductive agent to be divided into gas base method and coal-based method, is divided into shaft furnace, rotary kiln, rotary hearth furnace, retort (also claiming fixed bed), pot furnace (also claiming moving-bed), fluidized bed process or the like by reduction apparatus.Gas base method Shaft Furnace Direct Reduction Process accounts for more than 90% of direct-reduced iron ultimate production in the world, but to China and the few country of the many Sweet natural gases of some coals, has only the gas base method and the coal-based method that adopt coal gas.And gasification needs a succession of device, and investment and production cost are all big.Thereby domesticly in recent years built and generally adopt coal-based rotary kiln method and retort process making sponge iron in the direct-reduced iron factory that builds, though rotary kiln mechanization degree height, volumetric efficiency and plant factor are lower, investment and production cost height; Tunnel furnace, down-draft kiln, retort processes making sponge iron such as slope stove, the output investment ratio rotary kiln is low, but spare parts consumption is big, and production efficiency is low, causes production cost to increase.

In addition, adopt carbonaceous pelletizing to produce the many of direct-reduced iron now, it is ferriferous oxide and reductive agent to be mixed make pelletizing.Though this method helps reduction reaction, the impurity in the reductive agent of reduction back is not easily separated, influences the reduced iron quality.

The purpose of this invention is to provide a kind of pot furnace coal-based direct reduction iron production method, it is according to direct reduction reactor mechanism, combine the novel process of blast furnace ironmaking and coking by coke oven modern technique, strong to raw material and fuel tolerance, equipment is simple and reliable, reduce the suite of equipment investment of gasification, to join the simple reduction effect of carbon burden process outward good, can produce sponge iron by continuous large-scale, is fit to china natural resources and economic technology condition.

For finishing above-mentioned task, the solution that the present invention adopts is: the smart powder of iron is mixed, makes ball, is dried into cooled agglomerated pellet with compound binding agent; The reductive agent coal mixes the reduction furnace of packing into through broken, screening back with cooled agglomerated pellet and sweetening agent, and perhaps the image height stove is smelted iron the pot type reduction furnace of equally packing into by different level, by preheating.Reduction, process of cooling, cooled agglomerated pellet has been reduced into metallized pellet, furnace charge is discharged out of the furnace continuously or regularly again, carries out separating of direct-reduced iron and carbon residue then, and is complete to guarantee reduction and desulfurization, and impurity is stayed in the direct-reduced iron; Isolated bulk is reduced finished bin fine particle reduced iron and also be can be used as finished product through bonding behind the pressure ball again and go into finished bin.

Concrete technical process of the present invention is as follows: at first allocate a spot of compound binding agent (water glass, water and plant amylum) in the smart powder of the iron more than 67% grade, mix with stirrer, send into ball press and make ball; The pelletizing that extrudes is delivered to drying shed at 150 ℃, and cooled agglomerated pellet is made in flash baking in 30 minutes; A kind of (preferred long-flame coal) crushing and screening in the mill coals such as reductive agent coal such as long-flame coal, non-caking coal, meager coal, brown coal is become the particle of 5-30mm, mixes with cooled agglomerated pellet and sweetening agent (Wingdale) or layering (promptly the joining the carbon formula outward) pot type of packing into reduction furnace; Furnace charge slowly descends in the pot furnace (being the pot type shaft furnace) of secluding air, through preheating, reduction (800-1100 ℃), cooling three phases, generates direct-reduced iron, and is to be cooled to below 100 ℃, continuously or periodically furnace charge discharged by removal device; The furnace charge of discharging will be through screening and magnetic separation, isolate metallized pellet and cinder, metallized pellet is pressed+8mm, finished bin is delivered in two kinds of grain-size classifications of+4-8mm, the following powder granulous of general-4mm direct-reduced iron is allocated pressure ball behind the compound binding agent again into, make＞pelletizing of 8mm sends into another finished bin, as another grade product; How much at last the coal of nonferromugnetic material and slag are looked carbon content returns and uses or send the slag field.

The reduction main equipment has adopted the reciprocal quirk of a kind of level to add thermal reaction chamber, all keeps the pot type reduction furnace of reducing atmosphere at preheating, reduction, cooling three phases.

With cooled agglomerated pellet and mill coal and the sweetening agent layering directly reduction in the pot type reduction furnace of packing into.

Metallized pellet is separated with magnetic separation by screening, be equipped with compound adhesive in the claim 2, on ball press, be pressed into pelletizing again, as the direct-reduced iron finished product less than the 4mm powder.

The present invention has following advantage:

Owing to adopted the outer carbon formula method of joining in the above-mentioned solution, be cooled agglomerated pellet and reductive agent layering or be mixed into stove, residual coal and cinder after the carbonaceous pelletizing that has overcome common employing easily will reduce are stayed the intravital shortcoming of direct-reduced iron, improved the reduced iron quality, this technical process is short, can reach the purpose that obtains high-quality direct former iron again.

Reaching embodiment below with reference to the accompanying drawings is further described the present invention.

Fig. 1 is a process flow sheet of the present invention.

Illustrate according to above technical process.

With the smart powder (TFe＞67%) of 1.5 tons of iron, allocate compound binding agent (water glass of 7.5kg plant amylum+75kg water+15kg Baume concentration 40 degree) into, mix with stirrer, deliver to ball press and make ball, the ball that extrudes is sent into stoving oven again, under 150 ℃ of temperature,, make cooled agglomerated pellet through flash baking in 30 minutes; Get 500kg long-flame coal crushing and screening and become the 5-30mm fritter, with cooled agglomerated pellet and sweetening agent (30kg Wingdale), layering is packed in the reduction furnace, with 950-1050 ℃ of reduction, in stove, force to be cooled to below 100 ℃, discharge the 150kg furnace charge by discharge gate timing (per half an hour once); Sub-elect+8mm with vibratory screening apparatus and magnetic separator again, 4～-8mmDRI, be respectively charged into two finished bin, the metallization iron powder grain of general＜4mm is allocated 2% compound binding agent (as previously mentioned) into, is pressed into＞the above pelletizing of 8mm another finished bin of packing into.The remaining residual coal of sorting returns does fuel, and residue is sent into the slag field.

Claims

1, a kind of production method of pot furnace coal-based direct reduction iron, it is characterized in that: the smart powder of the iron more than 67% grade is mixed with compound binding agent, make ball, be dried into cooled agglomerated pellet, reductive agent coal crushing and screening is become the particle of 5-30mm, go into the pot type reduction furnace with cooled agglomerated pellet and sweetening agent, furnace charge slowly descends in the pot furnace of secluding air, through preheating, reduction (800-1100 ℃), be cooled to three phases below 100 ℃, generate direct-reduced iron, continuously or periodically furnace charge is discharged by removal device, furnace charge is through screening and magnetic separation, isolate direct-reduced iron and cinder, direct-reduced iron by+more than the 8mm, the product of two kinds of size ranges of+4-8mm is delivered to finished bin, and the following powder of-4mm is allocated compound binding agent again into and is pressed into ball as another grade product.

2, method according to claim 1, it is characterized in that: making the pelletizing step is, water and plant amylum break into paste, join in the smart powder of iron, add water glass again, mix, send into ball press then and make ball with stirrer, compound binding agent is made up of water, starch, water glass, and the ratio of the smart powder of iron, water, starch, water glass is: 200: 10: 1: 2.

3, method according to claim 1 is characterized in that: pelletizing is 150 ℃ of low temperature in the net belt type stoving oven, and cooled agglomerated pellet is made in flash baking in 30 minutes.

4, method according to claim 1 is characterized in that reductive agent adopts mill coals such as long-flame coal, non-caking coal, meager coal, brown coal.

5, method according to claim 1 is characterized in that: the reduction main equipment has adopted the reciprocal quirk of a kind of level to add thermal reaction chamber, all keeps the pot type reduction furnace of reducing atmosphere at preheating, reduction, cooling three phases.

6, the method for claim 1 is characterized in that cooled agglomerated pellet and mill coal and the sweetening agent layering directly reduction in the pot type reduction furnace of packing into.

7, the method for claim 1 is characterized in that metallized pellet being separated with magnetic separation by screening, is equipped with compound adhesive in the claim 2 less than the 4mm powder, is pressed into pelletizing again on ball press, as the direct-reduced iron finished product.