CN102168159B

CN102168159B - Reducing agent for carrying out direct reduction roasting on limonite and hematite to produce reduced iron

Info

Publication number: CN102168159B
Application number: CN2011100956863A
Authority: CN
Inventors: 孙体昌; 寇珏; 张继平
Original assignee: NINGXIA ZHANLV LOW CARBON TECHNOLOGY Co Ltd; University of Science and Technology Beijing USTB
Current assignee: NINGXIA ZHANLV LOW CARBON TECHNOLOGY Co Ltd; University of Science and Technology Beijing USTB
Priority date: 2011-04-15
Filing date: 2011-04-15
Publication date: 2013-05-01
Anticipated expiration: 2031-04-15
Also published as: CN102168159A

Abstract

The invention belongs to the field of ferrous metallurgy and relates to a reducing agent for carrying out direct reduction roasting on limonite and hematite to produce reduced iron. The invention is characterized in that the reducing agent is prepared by fully and evenly mixing coal, lime stone and sodium hydroxide in a certain proportion; a direct reduction roasting-magnetic method is utilized, iron, especially iron ore existing in the form of limonite and hematite is utilized as a raw material, the reducing agent provided by the invention is added so as to carry out direct reduction roasting, and then ore grinding and magnetic separation are carried out, thus obtaining directly-reduced iron product with the iron grade larger than or equal to 90 percent and the iron recovery rate larger than 80 percent; the reducing agent plays a role in generating reducing atmosphere and promoting the iron in the limonite and hematite of ore to be fully reduced into metal iron and then recycling metal iron through a magnetic method under the condition of anaerobic roasting; and the proportion of the coal to lime stone to sodium hydroxide in the reducing agent is 100:(5-4):(2.5-1). The reducing agent is less in using amount, low in cost and good in magnetic separation effect after use.

Description

The method of a kind of brown iron and hematite direct-reduction baked for producing reduced iron product

Technical field

The invention belongs to the ferrous metallurgy field, relate to a kind of iron ore that mainly exists with limonite and rhombohedral iron ore for iron, adopt the direct-reduction roasting method to produce the reductive agent of reduced iron, this technology mainly is to carry out reducing roasting by add a kind of reductive agent in limonite ore or hematite, be the brown iron in the iron ore, rhombohedral iron ore direct-reduction metallic iron, the processing method of then producing direct-reduced iron through ore grinding and low intensity magnetic separation.

Background technology

China's iron ore deposit deposit wretched insufficiency, in identified 576.71 hundred million t iron ore reserves, the economic base reserves only are 166.86 hundred million t, and lean ore is many, and rich ore is few, and the iron ore average grade only has 33%.Along with the process of industrialization of China is accelerated, the particularly fast development of steel industry, China has become Iron and Steel Production state the biggest in the world, and China is also growing to the demand of iron ore deposit simultaneously.The iron ore deposit of China can not satisfy the demand of steel industry far away at present, surpasses 60% iron ore raw material dependence on import, and the rising steadily of imported iron ore stone price of having to be forced to accept.Therefore how to greatest extent the domestic existing iron ore resource of development and utilization provides the iron ore raw material of capacity and high-quality for the continual and steady development of China's Iron And Steel Industry, become mineral processing in China field problem demanding prompt solution.

The brown iron of China, hematite reserves are very large, proven reserve are about 369.83 hundred million t, but chemical composition is fixing, iron-holder is very unstable, magnetic weak, flotability is poor, moisture content change is large because brown iron, rhombohedral iron ore have, the character such as easy mistake pulverizing in the comminution process, belong to a kind of unmanageable iron ore, adopt the beneficiation method of conventional physics and chemistry to be difficult to obtain the iron ore concentrate of iron grade more than 60%, and be difficult to obtain higher metal recovery rate.Adopt direct-reduction roasting-magnetic method to process refractory iron ore production Direct Reducing Iron Process and obtained good effect in the efficient utilization of Refractory iron ore stone, the method is used for brown iron, rhombohedral iron ore also is effective.But owing to adopting single coal to make reductive agent in the technique at present, not only cost is high, and iron recovery is on the low side, be difficult to bring into play the advantage of this technique, therefore the present invention improves original reductive agent, invented new reductive agent, and through facts have proved that repeatedly reductive agent that employing is invented carries out the direct-reduction roasting to brown iron, hematite and can improve direct-reduced iron grade and the rate of recovery, made brown iron, the choosing of this class of rhombohedral iron ore difficulty that utilization ratio is low in the past, difficultly efficiently utilized with mineral.

Summary of the invention

The present invention seeks to process exist in the refractory iron ore production Direct Reducing Iron Process single for existing direct-reduction roasting-magnetic method and make reductive agent with coal, the problem that the cost that causes is high and iron recovery is on the low side, invented new reductive agent, adopt direct-reduction roasting-magnetic separation process, the reduced iron grade of producing is greater than 90% direct-reduction iron product, brown iron, rhombohedral iron ore are fully reduced in roasting process, and reach and improve roasting efficient, the cost of reducing investment outlay, energy-saving and cost-reducing purpose.

The present invention relates to the reductive agent that a kind of brown iron and hematite direct-reduction baked for producing reduced iron are used, this reductive agent (is considered from the angle of cost take coal as main component, preferred volatile matter is greater than 30% brown coal), add simultaneously a certain proportion of Wingdale and sodium hydroxide formulated, possess better roasting effect than independent use coal as reductive agent.The reductive agent of inventing is owing to having added sodium hydroxide, can with brown iron, rhombohedral iron ore in gangue mineral react and generate new double salt, thereby destroy the structure of mineral, the metallic iron granularity that reduction is generated obviously increases, iron in the roasted ore is separated with the easier ore grinding of gangue mineral, can make metallic iron obtain fully effectively reclaiming through low intensity magnetic separation behind the ore grinding.Adopt that the iron grade can reach more than 90% in the reduced iron product of this reductive agent production, can be directly used in steel-making, the rate of recovery of iron is generally greater than 80%.This reductive agent has greatly improved the utilising efficiency of brown iron, rhombohedral iron ore, has simplified technical process.

The method of preparing this reductive agent is: limestone crushing is arrived-2mm, brown coal crushing arrives-4mm, make brown coal, Wingdale and sodium hydroxide in 100:(5～4): the ratio of (2.5～1) mixes, to different places of production ore, the component proportions of reductive agent is different, can suitably adjust according to the character of used iron ore.

Use the condition of this reductive agent to be: at first brown iron, rhombohedral iron ore to be crushed to certain particle size, fully mix with the reductive agent of inventing, roasting 40～80min under 1150～1200 ℃ of conditions of High Temperature Furnaces Heating Apparatus, the concrete time is according to the different in kind of ore and different; Roasting product carries out ore grinding through behind the naturally cooling in ball mill, the ore pulp mass concentration is about 60% during ore grinding, and product granularity-0.074mm accounts for about 50%～85%; Ore milling product magnetic separation under magneticstrength 110～200kA/m condition obtains the direct-reduction iron product.

Utilize reductive agent of the present invention, can effectively utilize brown iron, hematite to produce direct-reduced iron, the grade of iron and the rate of recovery can reach more than 90% and 80% respectively, thereby realize taking full advantage of of brown iron, rhombohedral iron ore.Compare as reductive agent with existing single coal, the reductive agent of inventing has following features:

Figure 2011100956863100002DEST_PATH_IMAGE002

It is few that the single coal of coal amount ratio that obtains the reduced iron product needed of identical grade and the rate of recovery is made reductive agent, therefore effectively saves the coal consumption, reaches energy-saving and cost-reducing effect;

Adopt the reductive agent invent to brown iron, rhombohedral iron ore carry out arriving of reducing roasting roasted ore, do not need fine grinding just can reach good magnetic separation effect.This be since the Wingdale that adds and sodium hydroxide can with brown iron, rhombohedral iron ore in the gangue mineral generation double salt that reacts, thereby destroy the internal structure of ore, simultaneously the iron granule size that generates is obviously increased, make reduced iron and the easier monomer dissociation of impurity in the roasted ore; Raw materials used kind is simple, and wide material sources, pollutant discharge amount are also few than additive method, is easy to process; 4. having avoided the higher fat coal of use cost is reductive agent, and the low brown coal of use cost, can effectively reduce the cost of reducing roasting process; The aerial oxidation of reduced iron of 5. can establishment producing has guaranteed the quality of direct-reduced iron.

Description of drawings

Accompanying drawing 1 is depicted as brown iron, hematite adds reductive agent direct-reduction roasting-magnetic separation process flow process.

Embodiment

For describing better the present invention, reductive agent provided by the invention is described in further detail with embodiment below in conjunction with accompanying drawing.

Embodiment 1

Certain limonite all iron content 49.55%, main gangue mineral is quartzy.The reducing roasting condition is: the consumption of reductive agent is 30%; Behind the mixing in retort furnace 1200 ℃ of lower reducing roasting 50min; Cooling; Be milled to granularity-0.074mm in concentration about 60% and account for 51%, in magneticstrength 198.73kA/m magnetic separation.Obtain iron grade 90.32%, the direct-reduced iron of iron recovery 88.69%.

Embodiment 2

Raw material is the hematite of certain iron content 33.75%, and main gangue mineral is quartzy.The reducing roasting condition is: the consumption of reductive agent is 15%; Behind the mixing in retort furnace 1200 ℃ of lower reducing roasting 40min; Cooling; Be milled to granularity-0.074mm in ore pulp mass concentration 60% and account for more than 75%, in magneticstrength 198.73kA/m magnetic separation.Obtain iron grade 91%, the direct-reduced iron of the rate of recovery 84.28%.

Embodiment 3

Raw material is iron grade 37.20%, and gangue is mainly kaolinite and illitic brown iron, red iron mixed ore.The reducing roasting condition is: the consumption of reductive agent is 20%; Behind the mixing in retort furnace 1150 ℃ of lower reducing roasting 60min; Cooling; Ore grinding under the condition of ore pulp mass concentration about 55% accounts for more than 80% to granularity-0.074mm, in magneticstrength 180kA/m magnetic separation.Obtain iron grade 90.25%, the direct-reduced iron of the rate of recovery 83.45%.

Claims

1. the method for a brown iron and hematite direct-reduction baked for producing reduced iron product, it is characterized in that: coal, Wingdale, sodium hydroxide are fully mixed by a certain percentage be prepared into reductive agent, and employing direct-reduction roasting-magnetic method, the iron ore that mainly exists take brown iron, rhombohedral iron ore form with iron is as raw material, add described reductive agent and carry out the direct-reduction roasting, then pass through mill ore magnetic selection, can obtain the iron grade more than or equal to 90%, the rate of recovery of iron is greater than 80% direct-reduction iron product; The effect of reductive agent is under the condition of anaerobic roasting, produces reducing atmosphere, promotes the iron that is present in brown iron, the rhombohedral iron ore in the ore fully to be reduced to metallic iron, then reclaims metallic iron through magnetic separation; The ratio of coal, Wingdale and sodium hydroxide is in the reductive agent: 100:(5～4): (2.5～1); The applicable technique of described reductive agent is that the direct-reduction roasting method is reduced limonite and rhombohedral iron ore in brown iron, the hematite; When carrying out take limonite, rhombohedral iron ore as main iron ore direct reducing with this reductive agent, do not need other additives.

2. the method for a kind of brown iron according to claim 1 and hematite direct-reduction baked for producing reduced iron product, it is characterized in that: the application conditions of reductive agent is among the described preparation method: at first brown iron, rhombohedral iron ore are crushed to certain particle size, fully mix with described reductive agent, roasting 40～80min under 1150～1200 ℃ of conditions of High Temperature Furnaces Heating Apparatus, the concrete time is according to the different in kind of ore and different; Roasting product carries out ore grinding through behind the naturally cooling in ball mill, the ore pulp mass concentration is 60% during ore grinding, and product granularity-0.074mm accounts for 50%～85%; Ore milling product magnetic separation under magneticstrength 110～200kA/m condition obtains the direct-reduction iron product.

3. the method for a kind of brown iron as claimed in claim 1 and hematite direct-reduction baked for producing reduced iron product is characterized in that coal in the reductive agent is greater than 30% brown coal with volatile matter.

4. the method for a kind of brown iron as claimed in claim 1 and hematite direct-reduction baked for producing reduced iron product is characterized in that brown iron, hematite add the product of roasting that obtains after the roasting of described reductive agent direct-reduction and should adopt ore grinding-low intensity magnetic separation method to reclaim the metallic iron that reduction generates.