CN1067436C

CN1067436C - Technology for directly reducing iron with coal base in pot furnace

Info

Publication number: CN1067436C
Application number: CN98119030A
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: 2001-06-20
Anticipated expiration: 2018-09-28
Also published as: CN1249350A

Abstract

The present invention relates to a method for directly producing reduced iron with a coal base in a pot furnace, which is characterized in that iron concentrate is added with binding agents to be manufactured into a cooled agglomerated pellets; by using non coking coal as reducing agents, the cooled agglomerated pellets are loaded in the pot furnace in a layering mode or a mixing mode; by three-stage processes of preheating, reduction and cooling, sponge iron is produced; the reduced iron is produced after ore selection and coal slag separation. The present invention integrates blast furnace process technical skill and coke furnace coking technical skill, and accords with the mechanism of direct reduction reaction. The product produced by the method of the present invention has good quality and high adaptability for raw materials and fuel. The present invention has the advantages of simple and reliable device, less investment and low production cost. Sponge iron can be continuously produced on a large scale, and the method of the present invention is suitable for resources and economic technical conditions of China.

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, can be divided into gas base method and coal-based method by reductive agent, is divided into methods such as shaft furnace, rotary kiln, rotary hearth furnace, retort (also claiming fixed bed), pot furnace (also claiming moving-bed), fluidized-bed by reduction apparatus.Gas base method Shaft Furnace Direct Reduction Process output 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, is fit to adopt the gas base method or the coal-based method of gasification.Yet gasification needs a succession of device, and investment and cost are all bigger, thereby has 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 but the rotary kiln mechanization degree is higher, volumetric efficiency and plant factor be lower, to crude fuel quality requirements height, investment and cost height; Retort processes making sponge iron such as tunnel furnace, down-draft kiln, slope stove, the output investment ratio kiln process is low, but spare parts consumption is big, production efficiency is low, causes production cost to increase.

In the applicant's utility model patent ZL96205053.9, a kind of pot furnace device of producing sponge iron with direct-reduction process is disclosed, it mainly is that grate by the body of heater of building by laying bricks or stones on the furnace bottom basis, combustion chamber, quirk, air flue, flue, retort and steel construction constitutes, quirk is that grouping, layering, level are staggered, and be looped around retort around; Retort can be identical some groups of structure, generally is the 1-8 group, every group 2-6; Quirk, combustion chamber are corresponding with the group number of retort; Air flue also is that grouping, layering, level are staggered, and it is located at the quirk bottom, is communicated with quirk.

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, impurity is not easily separated in the reductive agent of reduction back, 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 nuclear fuel adaptability, equipment is simple and reliable, reduces the suite of equipment investment of gasification, joins outward that the charcoal burden process is simple, reduction effect good, can produce sponge iron by continuous large-scale, be 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 is through mixing the reduction furnace of packing into cooled agglomerated pellet and sweetening agent behind the crushing and screening, and perhaps as the blast furnace ironmaking layering pot type reduction furnace of packing into, by preheating, reduction, process of cooling, cooled agglomerated pellet has been reduced into metallized pellet; Again furnace charge is discharged out of the furnace continuously or regularly, carry out separating of direct-reduced iron and charcoal residue then, complete to guarantee reduction and desulfurization, impurity is stayed in the direct-reduced iron; Isolated bulk is gone into finished bin, and the fine particle reduced iron also can be used as finished product again and goes into finished bin behind the bonding pressure ball.

Concrete technical process of the present invention is as follows:

At first make pelletizing, step is: water and plant amylum break into paste, allocate in the smart powder of the above iron of 67% grade, add water glass again, mix with stirrer, send into ball press and make ball.Compound binding agent is made up of water, starch, water glass, and the ratio of the smart powder water-starch of iron water glass is 200: 10: 1: 2; The pelletizing that extrudes is delivered to drying shed flash baking in 150 ℃, 30 minutes, makes cooled agglomerated pellet; A kind of (preferred long-flame coal) crushing and screening in the non-coking coal 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 charcoal 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, general-4mm powder granulous 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 level of above-mentioned utility model patent ZL96205053.9 to add thermal reaction chamber, has all kept the pot type reduction furnace of reducing atmosphere at preheating, reduction, cooling three phases.

Cooled agglomerated pellet mixed with mill coal and sweetening agent or the layering directly reduction in the pot type reduction furnace of packing into.

Metallized pellet is separated with magnetic separation by screening, be equipped with above-mentioned compound binding agent, 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 charcoal formula method of joining in the above-mentioned solution, i.e. cooled agglomerated pellet and reductive agent layering or be mixed into stove overcome residual coal and the cinder that common employing contain after the charcoal pelletizing easily will reduce and stayed the interior shortcoming of direct-reduced iron, improved the reduced iron quality.This technical process is short, can reach the purpose that obtains the high quality direct-reduced iron again.

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

Accompanying drawing 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, send ball press to make ball, the ball that extrudes is sent into stoving oven again, under 150 ℃ of temperature, through flash baking in 30 minutes, make cooled agglomerated pellet; Get 500kg long-flame coal crushing and screening and become the 5-30mm fritter, mix with cooled agglomerated pellet and sweetening agent (30kg Wingdale), in the reduction furnace of packing into, 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); Again with vibratory screening apparatus and magnetic separator sub-elect+8mm and+4-8mmDRI, be respectively charged into two finished bin; Allocate the metallization iron powder grain of-4mm into 2% compound binding agent (as previously mentioned), be pressed into the above pelletizing of 8mm another finished bin of packing into.The remaining residual coal of sorting returns makes fuel, and residue is sent into the slag field.

Claims

1, a kind of production method of pot furnace coal-based direct reduction iron is characterized in that:

(1) uses a kind of pot furnace device of producing sponge iron with direct-reduction process, it mainly is that grate by the body of heater of building by laying bricks or stones on the furnace bottom basis, combustion chamber, quirk, air flue, flue, retort and steel construction constitutes, it is characterized in that quirk is that grouping, layering, level are staggered, and be looped around retort around; Retort can be identical some groups of structure, generally is the 1-8 group, and every group 2-6, quirk, combustion chamber are corresponding with the group number of reaction; Air flue also is that the grouping-hierarchy level is staggered, and it is located at the quirk bottom, is communicated with quirk.

(2) making the pelletizing step is: water and plant amylum break into paste, join in the smart powder of iron, add water glass again, mix with stirrer, send into ball press then and make ball.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) reductive agent coal crushing and screening is become the particle of 5-30mm, with cooled agglomerated pellet and the sweetening agent pot type reduction furnace of packing into, furnace charge slowly descends in the pot furnace of secluding air, passes through preheating, reduction (800-1100 ℃), is cooled to three phases below 100 ℃, generates direct-reduced iron.

(4) 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 ,+product of two kinds of size ranges of 4-8mm delivers to finished bin, 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 is characterized in that reductive agent adopts non-coking coal such as long-flame coal, non-caking coal, meager coal, brown coal.

3, the method for claim 1 is characterized in that cold-pressing balls nodulizing, coal and Wingdale mixed by a certain percentage or layering is packed into and reduced in the pot furnace.