CN112176176A - Method for improving reducibility of natural lump ore - Google Patents
Method for improving reducibility of natural lump ore Download PDFInfo
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- CN112176176A CN112176176A CN201910599360.0A CN201910599360A CN112176176A CN 112176176 A CN112176176 A CN 112176176A CN 201910599360 A CN201910599360 A CN 201910599360A CN 112176176 A CN112176176 A CN 112176176A
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- lump ore
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
Abstract
The invention discloses a method for improving reducibility of natural lump ore, which comprises the following steps: determining a proper roasting temperature rise curve by using an experimental test method according to the content of the crystal water of the natural lump ore; selecting the corresponding temperature rise speed, end point temperature and heat preservation time of the roasting furnace according to the roasting temperature rise curve, and sending the natural lump ore to the roasting furnace for roasting; and naturally cooling the roasted lump ore, screening out large-particle-size lump ore, conveying the large-particle-size lump ore to a blast furnace, and smelting the large-particle-size lump ore together with sintered ore and pellet ore. According to the invention, the natural lump ore is roasted according to a certain heating rate, end point temperature and heat preservation time, so that the crystal water and carbonate in the natural lump ore are gradually decomposed, the pores in the lump ore are increased, cracks are generated on the surface, the contact area of reducing gas and the lump ore in the reduction process is increased, the reaction kinetic condition is improved, the reducibility of the lump ore is improved, and the reduction of the fuel consumption of a blast furnace is facilitated after the natural lump ore is added into the blast furnace.
Description
Technical Field
The invention relates to the technical field of steel smelting, in particular to a method for improving reducibility of natural lump ore.
Background
Lump ore is one kind of blast furnace burden, and is ore which can be directly mixed into a blast furnace for smelting without agglomeration and only through certain screening, and natural lump ore is cheaper in price and has higher cost advantage; the use proportion of the natural lump ore is improved, the cost reduction and the efficiency improvement can be realized, the use proportion of the sinter and the pellet can be reduced due to the increase of the lump ore proportion, and the environmental protection pressure caused by the yield increase of the sinter and the pellet can be reduced.
Since the lump ore belongs to raw ore which is not processed at high temperature, the reducibility is between that of sintered ore and pellet ore, and the factor for limiting the use ratio is provided. The reducibility is low, the fuel consumption of the blast furnace is high, and the coke ratio is high, so that the cost per ton of molten iron smelted by the blast furnace is increased.
Chinese patent CN201310402287 discloses a method for producing sintered ore containing high crystal water lump ore, although the patent technology mentions that the high crystal water natural lump ore can completely eliminate thermal explosion phenomenon during sintering process, greatly improve the high temperature metallurgical property of lump ore, thereby increasing the charging ratio of natural lump ore, reducing the raw material cost, etc. However, the patent technology mixes the lump ore and the iron ore powder for sintering, and the final product is sintered ore instead of independent lump ore; most importantly, during the sintering process, the lump ore reacts with fluxes such as lime and the like on the surface, so that the local mineral structure of the lump ore is changed, and the method is a method for sintering by mixing small-particle lump ore, which is the most important mineral powder, into a sintering mixture.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for improving the reducibility of natural lump ore so as to reduce the fuel cost of a blast furnace and the smelting cost of ton iron.
The purpose of the invention is realized by the following technical scheme:
a method for improving the reducibility of natural lump ore comprises the following steps:
s1, confirming a roasting temperature-rising curve, namely determining a proper roasting temperature-rising curve by using an experimental test method according to the content of the crystal water of the natural lump ore;
s2, roasting, namely selecting the corresponding temperature rise speed, end point temperature and heat preservation time of the roasting furnace according to a roasting temperature rise curve, and sending the natural lump ore to the roasting furnace for roasting; the temperature rise speed is inversely proportional to the content of the crystal water, and the heat preservation time is directly proportional to the content of the crystal water;
s3, cooling and screening, namely naturally cooling the roasted lump ore, screening out large-particle-size lump ore, conveying the large-particle-size lump ore to a blast furnace, and smelting the large-particle-size lump ore, the sintered ore and the pellet ore together.
Preferably, the experimental test method is thermogravimetric analysis.
Preferably, the temperature rising speed of the roasting furnace is 4-10 ℃/min.
Preferably, the end temperature of the roasting furnace is 700-1000 ℃.
Preferably, the heat preservation time of the roasting furnace is 30-90 min.
Preferably, the grain size of the large-grain-size lump ore is more than 5 mm.
The invention has the following beneficial effects: according to the invention, the natural lump ore is roasted according to a certain heating rate, end point temperature and heat preservation time, so that the crystal water and carbonate in the natural lump ore are gradually decomposed, the pores in the lump ore are increased, cracks are generated on the surface, the contact area of reducing gas and the lump ore in the reduction process is increased, the reaction kinetic condition is improved, the reducibility of the lump ore is improved, and the reduction of the fuel consumption of a blast furnace is facilitated after the natural lump ore is added into the blast furnace. Meanwhile, because the purchasing cost of the natural lump ore is relatively low, the use proportion of the lump ore can be improved and the raw material cost of blast furnace smelting is reduced after the processing method is adopted.
Detailed Description
The method provided by the invention is characterized in that the lump ore is pretreated before entering the furnace, namely, the temperature rise speed, the end point temperature and the heat preservation time are controlled, the natural lump ore is roasted, the crystal water and the carbonate in the natural lump ore are decomposed, uniform micropores are generated in the lump ore, cracks are generated on the surface of the lump ore, the dynamic condition of the reaction is improved in the reduction process, the contact area of the reducing gas and the ore is increased, the improvement of the reducibility of the lump ore is facilitated, the fuel ratio of the blast furnace is reduced, and the smelting cost of the blast furnace ton iron is reduced.
Specifically, the method for improving the reducibility of the natural lump ore comprises the following steps:
s1, confirming a roasting temperature-rising curve, namely determining a proper roasting temperature-rising curve by using an experimental test method according to the content of the crystal water of the natural lump ore;
s2, roasting, namely selecting the corresponding temperature rise speed, end point temperature and heat preservation time of the roasting furnace according to a roasting temperature rise curve, and sending the natural lump ore to the roasting furnace for roasting; the temperature rise speed is inversely proportional to the content of the crystal water, and the heat preservation time is directly proportional to the content of the crystal water;
s3, a cooling and screening step, wherein the roasted lump ore is naturally cooled, large-particle-size lump ore is screened out and sent to a blast furnace, the particle size of the large-particle-size lump ore is more than 5mm, and the large-particle-size lump ore is smelted together with sintered ore and pellet ore.
In the present invention, the baking temperature rise curve is obtained by Thermogravimetry (TG). Generally, the crystal water is decomposed at the temperature of 250-400 ℃, the carbonate is decomposed at the temperature of 800 ℃, but the carbonate content of the lump ore is low. And determining the end point temperature value according to the temperatures of different lump ore crystal water and carbonate beginning to decompose and ending in decomposition. In the roasting temperature rise curve determined by the invention, the temperature rise speed is inversely proportional to the content of the crystal water, and the heat preservation time is directly proportional to the content of the crystal water. The temperature rising speed of the roasting furnace is 4-10 ℃/min, the end temperature of the roasting furnace is 700-.
The temperature rise speed and the heat preservation time are determined according to different crystal water contents, namely the carbonate contents, so that the crystal water and the carbonate in the lump ore can be gradually released in the roasting process, pores are uniformly generated in the lump ore, and meanwhile, micro cracks are generated on the surface. The final temperature is required to be considered as the temperature to ensure that the crystal water and the carbonate can be decomposed, and the heat preservation time is required to ensure that the complete decomposition can be realized. After roasting at a certain temperature rise speed, end point temperature and heat preservation time, uniform pores are generated inside the lump ore, micro cracks are generated on the surface, the reducibility is improved, and the reduction of the fuel consumption of the blast furnace is facilitated after the lump ore is added into the blast furnace.
The rapid temperature rise can cause that water vapor can be formed after crystal water in the lump ore is evaporated, so that the pressure in the natural lump ore core particles is increased rapidly, a certain part with weaker strength or mineral with poorer crystal form can be fractured, cracks and even fragments are generated, the lump ore is cracked to generate powder, and the use is influenced. The temperature rise speed and the heat preservation time are set in the roasting process so as to ensure that the crystallized water and the carbonate in the lump ore can be gradually released in the roasting process, the crystallized water and the carbonate can be completely released after a certain heat preservation time, and the powder is not cracked and generated after the crystallized water and the carbonate are mixed into the blast furnace again.
The following is a demonstration by a specific experiment.
Selecting natural lump ore of 20-25mm, and mainly considering the requirements of experimental equipment on samples; this example was carried out in a muffle furnace in which the temperature rise rate and the holding time were controlled.
(1) Lump ore screening
Selecting natural lump ore A, B with two different crystal waters; wherein the crystal water content of the A lump ore is 8.45 percent, and the crystal water content of the B lump ore is 4.60 percent.
(2) Lump ore screening
And respectively crushing and screening the two selected natural lump ores with different crystal water contents, and screening out particles with the particle size range of 20-25 mm.
(3) Roasting of lump ore
Weighing 500g of the screened natural lump ore with the particle size of 20-25mm, putting the natural lump ore into a muffle furnace, setting the heating speed, the end point temperature and the heat preservation time, roasting, and naturally cooling after roasting.
(4) Firing protocol
Setting the temperature rise speed, the end point temperature and the heat preservation time to roast the lump ore for the performance comparison with the unprocessed natural lump ore.
TABLE 1 lump ore roasting Process parameter settings
(5) Post-baking treatment
And (5) naturally cooling the roasted lump ore in the step (5), and testing the medium-temperature reducibility of the cooled lump ore.
(6) Results of the experiment
TABLE 2 Medium temperature reducibility of lump ore before and after roasting
In the embodiment, two natural lump ores with different crystal waters are selected for testing, and as can be seen from table 2, after the natural lump ores are roasted at the set temperature rise speed, the set end point temperature and the set heat preservation time, the crystal waters and the carbonates in the lump ores are decomposed to generate pores and generate cracks on the surface, the dynamic conditions of gas-solid reaction are improved, the reducibility is improved, and the reducibility is averagely improved by 4.34%.
It should be understood that although the present description refers to embodiments, not every embodiment contains only a single technical solution, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the technical solutions in the embodiments can also be combined appropriately to form other embodiments understood by those skilled in the art.
The above-listed detailed description is only a specific description of a possible embodiment of the present invention, and they are not intended to limit the scope of the present invention, and equivalent embodiments or modifications made without departing from the technical spirit of the present invention should be included in the scope of the present invention.
Claims (6)
1. A method for improving reducibility of natural lump ore is characterized by comprising the following steps: comprises the following steps of (a) carrying out,
s1, confirming a roasting temperature-rising curve, namely determining a proper roasting temperature-rising curve by using an experimental test method according to the content of the crystal water of the natural lump ore;
s2, roasting, namely selecting the corresponding temperature rise speed, end point temperature and heat preservation time of the roasting furnace according to a roasting temperature rise curve, and sending the natural lump ore to the roasting furnace for roasting; the temperature rise speed is inversely proportional to the content of the crystal water, and the heat preservation time is directly proportional to the content of the crystal water;
s3, cooling and screening, namely naturally cooling the roasted lump ore, screening out large-particle-size lump ore, conveying the large-particle-size lump ore to a blast furnace, and smelting the large-particle-size lump ore, the sintered ore and the pellet ore together.
2. The method of claim 1, wherein: the experimental test method is thermogravimetric analysis.
3. The method of claim 1, wherein: the temperature rising speed of the roasting furnace is 4-10 ℃/min.
4. The method of claim 1, wherein: the end temperature of the roasting furnace is 700-1000 ℃.
5. The method of claim 1, wherein: the heat preservation time of the roasting furnace is 30-90 min.
6. The method of claim 1, wherein: the grain size of the large-grain-size lump ore is more than 5 mm.
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| CN201910599360.0A CN112176176A (en) | 2019-07-04 | 2019-07-04 | Method for improving reducibility of natural lump ore |
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| CN201910599360.0A CN112176176A (en) | 2019-07-04 | 2019-07-04 | Method for improving reducibility of natural lump ore |
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Citations (6)
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|---|---|---|---|---|
| CN1429920A (en) * | 2001-12-31 | 2003-07-16 | 新疆钢铁研究所 | Application of limonite as base material in pelletizing agglomerate production method |
| CN101104881A (en) * | 2007-07-13 | 2008-01-16 | 重庆钢铁(集团)有限责任公司 | Iron ore roasting technique |
| JP2013092539A (en) * | 2013-02-04 | 2013-05-16 | Nippon Steel & Sumitomo Metal | Evaluation method for blended iron ore for sintering |
| CN103160683A (en) * | 2011-12-14 | 2013-06-19 | 鞍钢股份有限公司 | Roasting pretreatment method for high crystal water content iron ore |
| CN106702145A (en) * | 2015-07-21 | 2017-05-24 | 宝山钢铁股份有限公司 | Method for intensifying sintering of limonite with high content of crystal water |
| CN108774683A (en) * | 2018-08-08 | 2018-11-09 | 胡明意 | A kind of high magnesium composite sinter and its production method |
-
2019
- 2019-07-04 CN CN201910599360.0A patent/CN112176176A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1429920A (en) * | 2001-12-31 | 2003-07-16 | 新疆钢铁研究所 | Application of limonite as base material in pelletizing agglomerate production method |
| CN101104881A (en) * | 2007-07-13 | 2008-01-16 | 重庆钢铁(集团)有限责任公司 | Iron ore roasting technique |
| CN103160683A (en) * | 2011-12-14 | 2013-06-19 | 鞍钢股份有限公司 | Roasting pretreatment method for high crystal water content iron ore |
| JP2013092539A (en) * | 2013-02-04 | 2013-05-16 | Nippon Steel & Sumitomo Metal | Evaluation method for blended iron ore for sintering |
| CN106702145A (en) * | 2015-07-21 | 2017-05-24 | 宝山钢铁股份有限公司 | Method for intensifying sintering of limonite with high content of crystal water |
| CN108774683A (en) * | 2018-08-08 | 2018-11-09 | 胡明意 | A kind of high magnesium composite sinter and its production method |
Non-Patent Citations (1)
| Title |
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| 王晓哲: "块矿气孔率和热分解对冶金性能影响研究", 《2017年全国高炉炼铁学术年会论文集（下）》 * |
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