CN103993166A - Method for improving grade of low-grade iron ore - Google Patents
Method for improving grade of low-grade iron ore Download PDFInfo
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- CN103993166A CN103993166A CN201410200461.3A CN201410200461A CN103993166A CN 103993166 A CN103993166 A CN 103993166A CN 201410200461 A CN201410200461 A CN 201410200461A CN 103993166 A CN103993166 A CN 103993166A
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Abstract
The invention provides a method for improving the grade of low-grade iron ore. The method comprises the following steps: respectively pretreating low-grade iron ore and coal, adding coal dust and an additive according to a certain proportion and preparing small balls with particle sizes of 3 to 8 mm by using a disc or drum balling machine after the content of treated iron ore and coal with a particle size of 0.074 mm is more than 50%, wherein clay minerals in the low-grade iron ore are used as a binder, or a small amount of binders like bentonite is added and uniformly mixed with treated iron ore and coal; and drying the prepared balls with a belt or cylindrical dryer, carrying out reduction by using a rotary kiln and then successively carrying out cooling and magnetic separation so as to obtain high-grade iron ore concentrate. With the method, low-grade iron ore can be effectively treated, the high-grade iron ore concentrate is obtained through granulation of the coal and the additive, direct reduction and magnetic separation, and the characteristics of energy conservation, high efficiency and rapidness are obtained.
Description
Technical field
The present invention relates to a kind of method of iron ore reduction roasting-magnetic separation, particularly coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in a kind of low-grade iron ore.
Background technology
Along with the development of modern steel industry, China's iron and steel output rises year by year, and domestic high-quality ferrolite supply is not enough, and problem is day by day serious, and Mineral resources have become " bottleneck " of restriction China development of iron & steel industry.High speed development along with Iron And Steel Industry, the demand of China iron deposit stone sharply increases, within 2009, Chinese imported iron ore stone amount is average annual so far increases by 21.8%, constantly riseing of import volume, also make the import interdependency of China iron deposit stone improve constantly, 2012, China iron deposit stone import interdependency was about 63%.
China iron deposit stone resource is rich and not rich, in approximately 58,100,000,000 t reserves (occupying the 4th, the world), 97% is lean ore, average grade is 33%, lower than 11 percentage points of World Iron ore average grades, iron grade is greater than 50% rich ore and only accounts for 2.7% (approximately 1,500,000,000 t), and most iron ores must can enter stove and smelt after beneficiation enrichment.China's iron ore type is various, and main Types and ratio are: magnetite type 55.40%, hematite-type 18.10%, spathic iron ore type 14.40%, vanadium titano-magnetite type 5.30%, specularite type 3.40%, limonite type 1.10%, mixed type 2.30%.The grade of low-grade iron ore refers to below 45%～50%.In China iron deposit stone ore bed, the iron ore material that most of iron ore contains two or more type, declines the washability of iron ore.While containing weak magnetism mineral as rhombohedral iron ore, specularite, pyrrhosiderite, spathic iron ore and limonite in iron ore, be usually difficult to effective utilization.For accounting for that the more than 25% granularity embedding cloth of total reserves is thin, gangue is mainly quartz and selecting the technique of preparing of ferric oxide ore still there is no breakthrough containing complicated difficults such as the rhombohedral iron ore of ferrosilicate and low-grade limonites.Adopt magnetizing roasting-magnetic separation can effectively process some low-grade iron ore, as gangue is mainly the hematite containing ferrosilicate, after magnetic separation, concentrate iron grade can reach 55%-66%, the rate of recovery 70%～85%
[1]yet, because being difficult to control and reducing the problem such as inhomogeneous, reduction process cause roasting energy consumption large, and product index is not high, and production cost is high
[2].Adopting the method for direct-reduction-magnetic separation to process low grade ore is the direction of current primary study, reduces 90min～120min at 1100 ℃～1200 ℃ of reduction temperatures, can obtain iron grade and the rate of recovery all at more than 90% concentrate
[3-6], can effectively process fine grain teeth cloth rhombohedral iron ore.Yet, because low-grade iron ore contains a large amount of gangue minerals (as SiO
2deng), in the temperature range of 1100 ℃～1200 ℃, can produce a large amount of fayalite liquid phases, the direct motion that direct-reduction is produced exerts an influence, and energy consumption is high, the time is long, still rest at present laboratory stage, the type iron ore deposit can not fully be recycled.
Reference:
[1] Ren Yafeng, Yu Yongfu. the Refractory red iron ores magnetizing roasting state of the art and developing direction. metal mine, 2005 (11): 20-23.
[2] Zhu Jiaji etc. Chinese iron technique of preparing [M]. Beijing: metallurgical industry press, 1994:328-338.
[3] Zhu Deqing, Zhai Yong, Pan builds, Deng. coal-based direct reduction-magnetic separation Super-fine lean hematite ore novel process [J]. Central South University's journal (natural science edition), 2008,39 (6): (the important difference of the document and the present invention wherein for 1132-1138.? also please illustrate, comprise the comparative illustration of effect)
[4] Zhu Deqing, Deng Xiulan, the spring iron army, etc. certain fine-grained dissemination lean hematite ore direct-reduction-low intensity magnetic separation test [J]. metal mine, 2012 (2): 60-62,66.
[5] Wei Yuxia, Sun Tichang, Kou Jue, etc. the impact [J] of interior coal blending consumption on certain refractory iron ore briquetting direct-reduction roasting. Central South University's journal (natural science edition), 2013.44 (4): 1305-1311.
[6] Xu Bin, Zhuan Jianming, Bai Guohua, etc. the research .[J of low-grade iron ore coal-based direct reduction] mineral products comprehensive utilization, 2001 (06): 20-24.
Summary of the invention
The object of the invention is to be to develop a kind of method that is obtained fine quality iron concentrate by low-grade iron ore, can effectively solve that low-grade iron ore is difficult to effectively utilize and reduction temperature is high in coal-based DR process, the recovery time long, easily ring formation and high in cost of production problem, thereby effectively reduce enterprise's production cost, can effectively alleviate the situation that high-quality iron ore deposit is in short supply and promote China Steel industrial expansion.
In order to solve the problems of the technologies described above, coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore provided by the invention, comprise following preparation process:
(1) low-grade iron ore and coal are carried out respectively to grade quality that pre-treatment to their granularities are less than 0.074mm and account for separately total mass more than 50%;
(2) through good iron ore and the coal of (1) step pre-treatment, by C/Fe mass ratio, be 0.2～0.5, and add NaCl or the Na that accounts for iron ore quality 2.0%～4.0%
2cO
3additive, and 0.5%～2.0% the wilkinite that adopts clay mineral that low-grade iron ore carries to account for iron ore quality as binding agent or interpolation is prepared burden as binding agent; After adding water-wet, batching is mixed into compound; It is the granulation bead of 3～8mm that mixture granulation is become to diameter;
(3) after the granulation bead (2) step being obtained is dried, in rotary kiln, carry out coal-based middle temperature fast restore, first by 200 ℃ of pre-heating temperature elevation temperature, be elevated to 920 ℃, time is 25min～50min, at 920 ℃～950 ℃ reducing roasting 10min～25min, make reducing material again, the isolated air cooling to 90 of cooling drum that reducing material is sprayed water by outside ℃～110 ℃, the separation of cooling rear employing dry magnetic separation obtains reducing roasting bead and carbon residue, and carbon residue returns to coal-based rotary kiln and uses;
(4) the resulting reducing roasting bead of (3) step is obtained to the iron ore concentrate of having upgrade through ore grinding, magnetic separation.
Pre-treatment described in step (1) is that ore grinding, profit mill or high pressure roller mill are processed.
Coal described in step (1) is to have brown coal, hard coal or the biomass carbon that the above reactive behavior of fugitive constituent 25% is high.
The particle diameter of the granulation bead that in step (2) prepared by employing balling disc or drum pelletizer is 3mm～8mm, and its moisture content is 7%～11%.
The middle granulation bead employing of step (3) cylindrical drier etc. is dried.
After granulation bead dry, should meet by the value of quality 0.5kg makes it from being less than 1.0mm Pulverization ratio after height is 0.5m group 3 times lower than 5% condition.
Described in above-mentioned steps (3) to granulation bead carry out drying treatment be utilize rotary kiln reduction section part thermal reduction gas out again combustion gases granulation bead is carried out to drying treatment, all the other hot waste gass carry out heat exchange and become preheated air as rotary kiln combustion air or adopt other UTILIZATION OF VESIDUAL HEAT IN measure to reclaim.
In step (4), cooling rear reducing roasting bead is through 10min～20min ore grinding, and the mass content that grinding particle size is less than 0.074mm is greater than 95%, and during magnetic separation, magneticstrength is 1.4～2.0KA/m.
Contriver is by the mass percent, C/Fe mass ratio 0.2～0.5, additive NaCl or the Na that grope to find to be less than by effective control iron ore and coal particle size 0.074mm repeatedly
2cO
3the comprehensive associated treatment of the several factors of 3～8mm of content 2.0%～4.0%, granulation bead, and make full use of the clay mineral carrying in low-grade iron ore or add wilkinite as binding agent, can be conducive to improve the balling-up of low-grade iron ore, resulting granulation bead can effectively be avoided the problems such as lump ore recovery time length, centerand edge reduction lack of homogeneity; Also can effectively avoid that fine ore reduction ventilation property is poor, dust flies upward and affects equipment direct motion and cause the problems such as iron ore loss with hot waste gas, the advantage of the inventive method is also to make the processing in reducing roasting stage can be more all even quicker.By the effectively collaborative and control efficiently of the present invention's each factor in early stage, the present invention can be in rotary kiln be realized low-grade iron ore coal blending and the additive coal-based middle temperature fast restore of granulating, only need be at the temperature of 920 ℃～950 ℃, and the recovery time foreshortens to 10min～25min, thereby coarse grain magnetite in iron ore is remained unchanged substantially, thicker rhombohedral iron ore is reduced into magnetite, be less than that 0.010mm rhombohedral iron ore part fast restore becomes metallic iron and under Additive, and other gangue mineral does not change substantially and can not hinder the reduction of ferriferous oxide, be conducive to the migration of metallic iron, merger is grown up, after magnetic separation, obtain fine quality iron concentrate.Adopt interior coal blending of the present invention and additive granulation direct-reduction, magnetic separation obtains the integrated approach of high-grade iron ore concentrate, can effectively process low-grade iron ore, have energy-conservation, efficiently, feature fast.Adopt method of the present invention, when rotary kiln reduces, burning is less than 80kg/t iron ore with energy consumption mark coal, far below conventional coal-based direct reduction rotary kiln energy consumption index.For raw material iron grade be 33.86%, SiO
2content is 40.61% low-grade iron ore and goes back that raw coal fixed carbon percentage composition is 55.83%, volatile matter percentage composition is 36.03%, adopt the present invention, can obtain reducing roasting bead nodulizing, after magnetic separation, can obtain concentrate grade and the rate of recovery all can be in the very good effect of 70% left and right, and some concentrate grades even also can reach 74.57% excellent effect.
Accompanying drawing explanation
Fig. 1 is schematic flow sheet of the present invention.
Embodiment
Below in conjunction with drawings and Examples, the invention will be further described.Wherein, raw material is that iron grade is 33.86%, SiO
2content is 40.61% low-grade iron ore and goes back that raw coal fixed carbon percentage composition is 55.83%, volatile matter percentage composition is 36.03%,
Comparative example 1
Taking granularity is 12～16mm low-grade iron ore 4kg, and C/Fe ratio is 0.81, and adopting charge preheating temperature in Rotary tube furnace is 35min from 200 ℃ of heating-up times that are elevated to 950 ℃, 950 ℃ of reducing roasting 25min; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.2KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 64.30%, and concentrate grade is 45.59%.
Comparative example 2
Taking granularity is 1～3mm low-grade iron ore 4kg, and C/Fe ratio is 0.5, and adopting charge preheating temperature in Rotary tube furnace is 35min from 200 ℃ of heating-up times that are elevated to 950 ℃, 950 ℃ of reducing roasting 25min; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.4KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 68.47%, and concentrate grade is 47.00%.
Comparative example 3
Take granularity for being less than 1mm low-grade iron ore 4kg, C/Fe ratio is 0.5, and adopting charge preheating temperature in Rotary tube furnace is 35min from 200 ℃ of heating-up times that are elevated to 950 ℃, 920 ℃ of reducing roasting 25min; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.4KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 83.77%, and concentrate grade is 47.63%.
Comparative example 4
Granularity is to be less than after 1mm low-grade iron ore adds 3% NaCl to press the agglomerate of rolling into a ball into 10mm, after dry, take 4kg, C/Fe ratio is 0.5, and adopting charge preheating temperature in Rotary tube furnace is 35min from 200 ℃ of heating-up times that are elevated to 950 ℃, 920 ℃ of reducing roasting 25min; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.4KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 49.89%, and concentrate grade is 62.50%.
Comparative example 5
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe than being 0, additive NaCl account for iron ore mass percent be 3.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopting charge preheating temperature in Rotary tube furnace is 35min from 200 ℃ of heating-up times that are elevated to 950 ℃, 950 ℃ of reducing roasting 25min; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 23.86%, and concentrate grade is 59.81%.
Comparative example 6
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe than being 0.4, additive NaCl account for iron ore mass percent be 0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopting charge preheating temperature in Rotary tube furnace is 35min from 200 ℃ of heating-up times that are elevated to 950 ℃, 950 ℃ of reducing roasting 25min; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 72.52%, and concentrate grade is 52.42%.
Comparative example 7
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe than being 0.4, additive NaCl account for iron ore mass percent be 3% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt charge preheating temperature in Rotary tube furnace to be elevated to heating-up time of 950 ℃ while being 80min from 200 ℃, then 950 ℃ of reducing roasting 25min; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 69.49%, and concentrate grade is 61.45%.
Embodiment 1
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 52.32%, interior coal blending C/Fe than being 0.3, additive NaCl account for iron ore mass percent be 3.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt in Rotary tube furnace charge preheating temperature from 200 ℃ of heating-up times that are elevated to 920 ℃ be 35min; Adopt 920 ℃ of reducing roasting 20min of Rotary tube furnace; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 62.54%, and concentrate grade is 72.50%.
Embodiment 2
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 65.01%, interior coal blending C/Fe than being 0.4, additive NaCl account for iron ore mass percent be 3.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt in Rotary tube furnace charge preheating temperature from 200 ℃ of heating-up times that are elevated to 950 ℃ be 35min; Adopt 950 ℃ of reducing roasting 20min of Rotary tube furnace; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 70.21%, and concentrate grade is 74.43%.
Embodiment 3
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe than being 0.4, additive NaCl account for iron ore mass percent be 3.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt in Rotary tube furnace charge preheating temperature from 200 ℃ of heating-up times that are elevated to 950 ℃ be 35min; Adopt 950 ℃ of reducing roasting 10min of Rotary tube furnace; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 68.62%, and concentrate grade is 71.37%.
Embodiment 4
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe than being 0.4, additive NaCl account for iron ore mass percent be 3.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt in Rotary tube furnace charge preheating temperature from 200 ℃ of heating-up times that are elevated to 950 ℃ be 35min; Adopt 950 ℃ of reducing roasting 25min of Rotary tube furnace; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 75.24%, and concentrate grade is 72.18%.
Embodiment 5
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe than being 0.2, additive NaCl account for iron ore mass percent be 3.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt in Rotary tube furnace charge preheating temperature from 200 ℃ of heating-up times that are elevated to 920 ℃ be 35min; Adopt 920 ℃ of reducing roasting 25min of Rotary tube furnace; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 66.41%, and concentrate grade is 67.49%.
Embodiment 6
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe than being 0.4, additive NaCl account for iron ore mass percent be 2.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt in Rotary tube furnace charge preheating temperature from 200 ℃ of heating-up times that are elevated to 950 ℃ be 35min; Adopt 950 ℃ of reducing roasting 25min of Rotary tube furnace; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 71.11%, and concentrate grade is 68.01%.
Embodiment 7
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe than being 0.2, additive NaCl account for iron ore mass percent be 4.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt in Rotary tube furnace charge preheating temperature from 200 ℃ of heating-up times that are elevated to 950 ℃ be 35min; Adopt 950 ℃ of reducing roasting 25min of Rotary tube furnace; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 69.13%, and concentrate grade is 74.57%.
Embodiment 8
Coal blending and the additive coal-based middle temperature fast restore-magnetic selection method of granulating in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe ratio is 0.3, additive Na
2cO
3account for iron ore mass percent and be 3.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt in Rotary tube furnace charge preheating temperature from 200 ℃ of heating-up times that are elevated to 950 ℃ be 35min; Adopt 950 ℃ of reducing roasting 25min of Rotary tube furnace; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 70.13%, and concentrate grade is 68.09%.
Embodiment 9
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe than being 0.4, additive NaCl account for iron ore mass percent be 3.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt in Rotary tube furnace charge preheating temperature from 200 ℃ of heating-up times that are elevated to 950 ℃ be 25min; Adopt 950 ℃ of reducing roasting 25min of Rotary tube furnace; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 74.65%, and concentrate grade is 71.89%.
Embodiment 10
Coal blending and the coal-based middle temperature fast restore-magnetic selection method of additive granulation in low-grade iron ore, the mass percent that low-grade iron ore and coal are less than 0.074mm is after pretreatment 71.41%, interior coal blending C/Fe than being 0.4, additive NaCl account for iron ore mass percent be 3.0% account for wilkinite that iron ore mass percent is that 1.5% raw material mixes, to become diameter be the bead of 3～8mm in disk pelletizing; After granulation bead is dry, adopt in Rotary tube furnace charge preheating temperature from 200 ℃ of heating-up times that are elevated to 950 ℃ be 50min; Adopt 950 ℃ of reducing roasting 25min of Rotary tube furnace; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.8KA/m magnetic separation; The rate of recovery that obtains result magnetic separation of iron ore concentrate is 68.45%, and concentrate grade is 68.78%.
Claims (8)
1. the method that low-grade iron ore is upgrade, is characterized in that, comprises following preparation process:
(1) low-grade iron ore and coal are carried out respectively to grade quality that pre-treatment to their granularities are less than 0.074mm and account for separately total mass more than 50%;
(2) through good iron ore and the coal of (1) step pre-treatment, by C/Fe mass ratio, be 0.2～0.5, and add NaCl or the Na that accounts for iron ore quality 2.0%～4.0%
2cO
3additive, and 0.5%～2.0% the wilkinite that adopts clay mineral that low-grade iron ore carries to account for iron ore quality as binding agent or interpolation is prepared burden as binding agent; After adding water-wet, batching is mixed into compound; It is the granulation bead of 3～8mm that mixture granulation is become to diameter;
(3) after the granulation bead (2) step being obtained is dried, in rotary kiln, carry out coal-based middle temperature fast restore, first by 200 ℃ of pre-heating temperature elevation temperature, be elevated to 920 ℃, time is 25min～50min, at 920 ℃～950 ℃ reducing roasting 10min～25min, make reducing material again, the isolated air cooling to 90 of cooling drum that reducing material is sprayed water by outside ℃～110 ℃, the separation of cooling rear employing dry magnetic separation obtains reducing roasting bead and carbon residue, and carbon residue returns to coal-based rotary kiln and uses;
(4) the resulting reducing roasting bead of (3) step is obtained to the iron ore concentrate of having upgrade through ore grinding, magnetic separation.
2. the method that a kind of low-grade iron ore according to claim 1 is upgrade, is characterized in that, the pre-treatment described in step (1) is that ore grinding, profit mill or high pressure roller mill are processed.
3. the method that a kind of low-grade iron ore according to claim 1 is upgrade, is characterized in that, the coal described in step (1) is to have brown coal, hard coal or the biomass carbon that the above reactive behavior of fugitive constituent 25% is high.
4. the method that a kind of low-grade iron ore according to claim 1 is upgrade, is characterized in that, in step (2), compound adopts balling disc or drum pelletizer to granulate, and the moisture content of the granulation bead obtaining is 7%～11%.
5. the method that a kind of low-grade iron ore according to claim 1 is upgrade, is characterized in that,
In step (3), granulation bead adopts cylindrical drier dry.
6. the method that a kind of low-grade iron ore according to claim 5 is upgrade, is characterized in that, should meet by the value of quality 0.5kg and make it from being less than 1.0mm Pulverization ratio after height is 0.5m group 3 times lower than 5% condition after granulation bead dry.
7. the method that a kind of low-grade iron ore according to claim 1 is upgrade, is characterized in that,
Described in above-mentioned steps (3) to granulation bead carry out drying treatment be utilize rotary kiln reduction section part thermal reduction gas out again combustion gases granulation bead is carried out to drying treatment, all the other hot waste gass carry out heat exchange and become preheated air as rotary kiln combustion air or adopt other UTILIZATION OF VESIDUAL HEAT IN measure to reclaim.
8. the method that a kind of low-grade iron ore according to claim 1 and 2 is upgrade, it is characterized in that: in step (4), cooling rear reducing roasting bead is through 10min～20min ore grinding, the mass content that grinding particle size is less than 0.074mm is greater than 95%, and during magnetic separation, magneticstrength is 1.4～2.0KA/m.
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| CN201410200461.3A Active CN103993166B (en) | 2014-05-13 | 2014-05-13 | A kind of method that low-grade iron ore is upgrade |
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Cited By (6)
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| CN104862440A (en) * | 2015-03-19 | 2015-08-26 | 中南大学 | Low-grade iron ore direct reduction method |
| CN106119456A (en) * | 2016-08-01 | 2016-11-16 | 江苏省冶金设计院有限公司 | Prepare the method and system of ferrum |
| CN106591572A (en) * | 2017-01-06 | 2017-04-26 | 中南大学 | Method for reinforcing preparation and reduction of carbon-containing pellets in iron ore |
| CN108374066A (en) * | 2018-03-30 | 2018-08-07 | 唐竹胜 | A kind of method of the biradical association type low temperature fast deep direct reduced iron of the double kilns of powdery iron ore |
| CN108690909A (en) * | 2017-04-05 | 2018-10-23 | 祁东县顺达矿业有限公司 | The method that kiln is tied in preventing rotary kiln from producing |
| CN111809044A (en) * | 2020-07-27 | 2020-10-23 | 北京科技大学 | Multi-source complex low-grade iron ore resource utilization method and high-quality composite iron-making furnace burden |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104862440A (en) * | 2015-03-19 | 2015-08-26 | 中南大学 | Low-grade iron ore direct reduction method |
| CN106119456A (en) * | 2016-08-01 | 2016-11-16 | 江苏省冶金设计院有限公司 | Prepare the method and system of ferrum |
| CN106591572A (en) * | 2017-01-06 | 2017-04-26 | 中南大学 | Method for reinforcing preparation and reduction of carbon-containing pellets in iron ore |
| CN108690909A (en) * | 2017-04-05 | 2018-10-23 | 祁东县顺达矿业有限公司 | The method that kiln is tied in preventing rotary kiln from producing |
| CN108374066A (en) * | 2018-03-30 | 2018-08-07 | 唐竹胜 | A kind of method of the biradical association type low temperature fast deep direct reduced iron of the double kilns of powdery iron ore |
| CN108374066B (en) * | 2018-03-30 | 2019-07-16 | 唐竹胜 | A kind of method of the biradical association type low temperature fast deep direct reduced iron of the double kilns of powdery iron ore |
| CN111809044A (en) * | 2020-07-27 | 2020-10-23 | 北京科技大学 | Multi-source complex low-grade iron ore resource utilization method and high-quality composite iron-making furnace burden |
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