CN111074037B - Process method for upgrading structure of manganese-rich slag smelting product - Google Patents

Abstract

The invention discloses a process method for upgrading a manganese-rich slag smelting product structure, which uses low-manganese high-iron low-manganese ores at home and abroad as raw materials, and adopts a pyrometallurgy enrichment technology to smelt manganese-rich slag and high-manganese pig iron by using a manganese-rich slag furnace, wherein the high-manganese pig iron contains 5-6% of manganese. The high manganese iron is further hot-charged into a converter for further smelting through a converter top-bottom combined blowing steelmaking process, high-quality manganese-rich slag and semisteel are blown and smelted from the high manganese iron by adopting a high scrap-to-steel ratio and a double-slag method operation process, and the semisteel is further deoxidized, decarburized, dephosphorized and alloyed to be smelted into 20MnSi equivalent series molten steel. The production method can save the silicon-manganese alloy by more than 12kg/t in the using process, and simultaneously produce high-quality manganese-rich slag products.

Description

Process method for upgrading structure of manganese-rich slag smelting product

Technical Field

The invention relates to the field of improving manganese recovery rate of manganese-rich slag and deep processing of high-manganese molten iron by using manganese-rich slag pyrometallurgy and ferrous metallurgy technologies, in particular to a process method for upgrading a structure of a manganese-rich slag smelting product.

Background

The manganese-rich slag furnace smelting manganese-rich slag belongs to a complex refractory metal ore high-efficiency separation technology, a low-grade complex refractory ore high-efficiency metallurgy technology and a combined associated resource and low-grade ore comprehensive utilization technology which are key technologies of resource comprehensive utilization encouraged by China. At present, the grade of the domestic low-manganese high-iron ore is 8-12% of manganese, 30-38% of iron, the foreign low-manganese high-iron ore (20-32% of manganese, 18-22% of iron) takes south Africa high-iron, Vietnam high-iron, Malay high-iron and Burma high-iron as main mineral sources, and the reserves of the foreign low-manganese high-iron manganese ore are huge. The manganese-rich slag is produced by a pyrometallurgy enrichment technology to obtain high-quality silicomanganese alloy with about 35 percent of manganese content, more than 25 Mn/Fe and less than 0.001P/Mn, but a byproduct of high-manganese pig iron (5-6 percent of manganese) is generated, the manganese cannot be completely extracted and recovered, the high-manganese pig iron can only be used as a cold charge for converter smelting, and more than 80 percent of manganese in the smelting process cannot be well recovered and reused by oxidation.

With the continuous expansion of the production scale of silicon-manganese alloy in China, the demand of high-quality silicon-manganese alloy for rich manganese ore in submerged arc furnace smelting is getting larger. While rich ores in the reserves of manganese ore resources in China only account for about 5 percent, most of the rich ores exist in poor manganese ores or ferro-manganese ores, and complex refractory ores containing phosphorus and iron account for a large proportion. Only manganese-rich slag smelting, namely, a pyrogenic process enrichment technology can be adopted for treatment, and the enrichment principle of the manganese-rich slag smelting is mainly iron removal and deoxidation (also called chemical weightlessness). However, the manganese content of the high-manganese pig iron which is a byproduct generated by smelting manganese-rich slag in the manganese-rich slag furnace reaches 5-6%, and only the manganese-rich slag furnace process can not completely recover manganese, so that the cost is relatively high. Manganese elements in the molten iron are further enriched by the process of hot charging the high-manganese iron into the converter, and meanwhile, the byproduct high-manganese iron is upgraded to molten steel (20MnSi), so that the cost of fire enrichment of the manganese-rich slag can be greatly reduced, the consumption of silicon-manganese alloy of steel-making HRB400e series steel is reduced, and the method has great significance for the development of the manganese-rich slag industry and the technical field of ferrous metallurgy.

At present, a large amount of by-product high manganese pig iron is produced in the production process of manganese-rich slag. The by-product high manganese molten iron is poured into a breaded iron block by adopting a pig casting machine process and sold to various steel mills, and is used as a cold charge additive for converter smelting, and manganese (5-6%) in the high manganese molten iron is almost completely oxidized and blown away, so that the manganese-rich slag smelting cost is high, and meanwhile, the manganese resource cannot be efficiently recycled. Therefore, the smelting process of hot charging the high manganese molten iron into the converter by adopting the high manganese molten iron further enriches manganese in the high manganese molten iron into manganese-rich slag, and upgrades the high manganese molten iron into semisteel, so that the high manganese molten iron finally becomes qualified steel and becomes the problem to be solved urgently.

Disclosure of Invention

The invention aims to provide a process method for upgrading a manganese-rich slag smelting product structure on the basis of the prior art, which is applied by taking low-manganese high-iron low-manganese ores at home and abroad as raw materials and adopting a pyrometallurgy enrichment technology to smelt manganese-rich slag and high-manganese pig iron by using a manganese-rich slag furnace, wherein the high-manganese pig iron contains 5-6% of manganese. The high manganese iron is further hot-charged into a converter for further smelting through a converter top-bottom combined blowing steelmaking process, high-quality manganese-rich slag and semisteel are blown and smelted from the high manganese iron by adopting a high scrap-to-steel ratio and a double-slag method operation process, and the semisteel is further deoxidized, decarburized, dephosphorized and alloyed to be smelted into 20MnSi equivalent series molten steel.

The invention is realized by the following technical scheme:

a process method for upgrading the structure of a manganese-rich slag smelting product, wherein the production method comprises the following steps:

s1, preparing materials for a manganese sintering process: sintering low-manganese high-iron high-sulfur powder (Fe 35-38%, Mn 5-10%, S is more than or equal to 0.4%, SiO2 is more than or equal to 19-27%), south African high-iron powder (Fe 24-27%, Mn 26-27.5%, AL2O3 is more than or equal to 3-7%) and domestic high-sulfur iron fine powder (Fe 64-65%, S is more than or equal to 2.6-3.0%) as production raw materials;

s2, preparing manganese-rich slag: manganese-rich slag is produced by adding 60 percent of manganese sinter (Mn13-15 percent and Fe39-45 percent) produced by a manganese sintering process, 30 percent of high-aluminum manganese ore (Fe20-23 percent, Mn29-33 percent and AL2O3 which are more than or equal to 9-12 percent), and 10 percent of low-manganese high-iron ore (Mn5-10 percent, Fe35-38 percent, S which is more than or equal to 0.5 percent and P which is more than or equal to 0.3 percent) into production raw materials;

s3, manganese-rich slag whole grain and high-manganese molten iron transfer: naturally cooling the produced manganese-rich slag in the water-cooled slag in front of the converter for 5 hours, and then drawing the manganese-rich slag to a granulating workshop for granulating treatment, simultaneously drawing the produced high-manganese molten iron to a converter workshop through a hot metal ladle car, uniformly mixing the high-manganese molten iron in a mixer furnace, heating to about 1300 ℃, adding the high-manganese molten iron into the converter for oxygen blowing;

s4, matching the structural ingredients of the steel materials entering the furnace: the molten iron uses the physical heat of 1250 ℃ and 1300 ℃, and the content of C is as follows: 4.2-4.5%, Si: 0.1-0.3%, Mn: 3-6%, S: 0.01-0.02%, P: 0.12-0.150%, and the proportion is as follows: the scrap steel ratio is 40-50%, the high manganese molten iron consumption is 700 plus 800kg/t, the lime is 65kg/t, the dolomite is 30kg/t, and the comprehensive manganese Mn of the steel material fed into the furnace is 3-4%;

s5, primary slagging blowing: the lance position control adopts a four-section operation mode of constant-pressure rheologic lance 'low-medium-high-low', the basic lance position is 700 + 1400mm, the oxygen supply flow is reduced at the early stage, bottom blowing is carried out, a bottom blowing system is not arranged at the middle and later stages, the oxygen supply pressure is 0.6-0.9MPa, the oxygen supply intensity is 1.8-3.0m3/min.t, a flux is added before the converter is blown, the oxygen pressure is 0.65MPa, the oxygen supply intensity is about 1.8m3/min.t, the lance position is ignited at 900mm, the blast can be rapidly formed in 1-2 min, manganese Mn is rapidly and largely oxidized to form (MnO.SiO2), the (MnO) in the slag is rapidly increased along with the increase of (CaO), the (MnO) in the slag is rapidly increased to ((MnO.SiO2) +2(CaO) + (MnO), the lance position is lifted to about 1300mm after the blast is carried out for 1-3 min, the temperature rise is inhibited, the content of the [ Mn ] + (FeO) in the slag is increased to promote the FeO ] + (MnO) to react, the slag disk is reversely stirred for 5-7 min, the slag pan is immediately transported to a slag treatment room for natural cooling to obtain manganese-rich slag with chemical components of MnO 38-45%, SiO 223-27%, MgO4.5%, CaO 12-16% and FeO 16-18%;

s6, secondary slagging blowing: carrying out secondary slagging blowing, after blowing at the middle lance position of 1100-1200mm of the blowing lance position for 2 minutes, lifting the lance to the high lance position of 1400-1500mm for 3 minutes, and then pressing the lance to 800mm deep blowing and carbon-pulling operation according to the flame at the furnace mouth, so as to improve the end point residual manganese Mn content, mainly improving the residual manganese content in molten steel by improving the end point temperature, reducing the FeO content in slag, improving the end point carbon C content and other measures, advancing the carbon-pulling time, prolonging the carbon-pulling time (40-60S), improving the end point residual manganese, reducing the alloy dosage during alloying, obtaining the residual manganese rate in steel of more than 20 percent, obtaining the MnO with 0.08-0.12 percent of residual manganese and 0.15-0.2 percent of carbon, and enriching the manganese slag of 22-27 percent;

s7, post-processing: after the furnace is processed by semi-steel decarburization dephosphorization alloying, the continuous casting and continuous rolling treatment is carried out to form a material, and the iron removal treatment is carried out on the manganese-rich slag at the end point.

Furthermore, a process method for upgrading the structure of a manganese-rich slag smelting product is characterized in that a flux is added in the secondary slagging blowing process, so that the terminal alkalinity of the secondary slagging blowing process is kept at 2.5-3.0.

The residual manganese in the blowing process of the converter increases along with the increase of the original manganese content, the temperature is lower in the initial smelting stage, the FeO content in the slag is high, so that the manganese is oxidized violently, when the manganese content in the molten iron is higher, the manganese is not oxidized completely, along with the rapid rise of the temperature and the violent oxidation of carbon, the FeO content in the slag is reduced, the oxidation reaction of the manganese is inhibited and weakened, even the manganese is reduced from the slag, so that the manganese content in the molten steel at the end point is inevitably high in the smelting of the high-manganese molten iron. The higher the [ Mn ] of the molten iron, the higher the terminal residual Mn ] is.

Manganese has a strong affinity for oxygen and oxidation of manganese in converter steelmaking is mainly manifested in the early stages of converting. The free energy is increased along with the increase of the temperature of the molten pool, the oxidation reaction trend of manganese is weakened, and when the smelting is carried out to the later stage, the manganese oxide in the slag begins to be reduced and the 'manganese return' occurs. In this case, the higher the temperature, the more the manganese oxide tends to be reduced, and the manganese content in the steel also increases. When the carbon drawing temperature is increased, the residual manganese in the steel is increased.

On one hand, the alkalinity of the slag is high, and the slag amount is large under certain conditions, so that the absolute amount of MnO which can be contained in the slag in an equilibrium state is relatively increased, and the residual manganese [ Mn ] in the equilibrium state can be reduced; on the other hand, the basicity is increased and the acidic oxides are completely bound by CaO. The activity of MnO in the slag is thus increased. It shows that when the alkalinity is high, the slag amount is large, and the influence of the terminal residual manganese [ Mn ] is mainly exerted. The double effects of the final slag R and the large slag quantity on the terminal manganese [ Mn ] residue are mutually offset.

The end point residual manganese [ Mn% ]increaseswith an increase in the end point carbon [ C% ]. When the end point carbon (C%) is less than or equal to 0.1%, the end point residual manganese (Mn%) is less than or equal to 0.8%, and the end point slag (MnO%) is 20%

At present, a large amount of by-product high-manganese pig iron is generated in the production process of manganese-rich slag, manganese (5-6%) in high-manganese molten iron is almost completely oxidized and blown to be damaged, the smelting cost of the manganese-rich slag is high, and meanwhile, manganese resources cannot be efficiently recycled, so the application provides a process method for upgrading the structure of a manganese-rich slag smelting product, the by-product high-manganese molten iron (physical heat is about 1300 ℃) produced by a manganese-rich slag furnace is hot-charged into a top-bottom re-blowing converter through a molten iron tank, and a 'double slag method operation' process is adopted, because the content of manganese in molten iron is up to 3-6%, the advantage of low sulfur (S is less than or equal to 0.02%) in the high-manganese molten iron is utilized, and the use amount of secondary fluxing agent (2.8-3.0) is increased by increasing the ratio of scrap steel, the slag (1.5-2.0), the gun position control, the final slag (FeO) control, the gun operation time (greater than or equal to 50S) and the secondary slagging increase the use amount, The end point temperature is controlled at 1600-1660 ℃, the carbon level is increased (0.12% -0.20%), the end point carbon level is increased, the steel slag oxidation is reduced, and the improvement of the residual manganese is beneficial to the improvement of the residual manganese from the two conditions of thermodynamics and kinetics. And the converter bottom blowing process is utilized to reduce the oxygen supply strength, increase the converter height ratio and other process improvements, the semi-steel is continuously blown, decarbonized and dephosphorized, and finally qualified molten steel components are produced, alloyed and then continuously cast and continuously rolled into the finished product.

In summary, the following beneficial effects of the invention are:

the invention relates to a process method for upgrading a manganese-rich slag smelting product structure, which adopts a pyrometallurgical enrichment technology to smelt manganese-rich slag and high-manganese pig iron by using a manganese-rich slag furnace, wherein the high-manganese pig iron contains 3-6% of manganese. The high manganese iron is further hot-charged into the converter for further smelting through a converter top-bottom combined blowing steelmaking process, the high manganese iron is blown into high-quality manganese-rich slag and semisteel by adopting a high scrap-to-steel ratio and a double-slag method operation process, the semisteel is further deoxidized, decarburized, dephosphorized and alloyed into 20MnSi equivalent series molten steel, the silicon-manganese alloy is saved by about more than 12kg/t in the converter technological process, and meanwhile, a high-quality manganese-rich slag product is produced.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

Examples

As shown in fig. 1, a process for upgrading the structure of a manganese-rich slag smelting product comprises the following steps: the method comprises the steps of sintering domestic low-manganese high-iron high-sulfur powder (Fe 35-38%, Mn 5-10%, S is more than or equal to 0.4%, SiO2 is more than or equal to 19-27%), south African high-iron powder (Fe 24-27%, Mn 26-27.5%, AL2O3 is more than or equal to 3-7%) and domestic high-sulfur iron fine powder (Fe 64-65%, S is more than or equal to 2.6-3.0%), sintering the mixture according to the process requirements of the sinter indexes of Mn + Fe is more than or equal to 55%, Mn is more than or equal to 13%, SiO2 is more than or equal to 12-15%, AL2O3 is less than or equal to 5.5%, S is less than or equal to 0.3%, FeO is more than or equal to 15-18%, R3 is less than or equal to 0.35-0.45%, adding 60% of manganese sinter (Mn 13-15%, Fe 39-45%) and high-aluminum manganese ore (Fe 20-23%, Mn 29-33%, Al2O 3% is more than or equal to 3-369-12%), p is more than or equal to 0.3 percent) or high-phosphorus iron ore (Fe58-63 percent, S is more than or equal to 0.2 percent, P is more than or equal to 0.7 percent) is added with 10 percent, the ratio of slag to coal per ton is 70kg, and the oxygen enrichment rate is 5.5 percent. The materials are mixed according to the process requirements that the indexes of the manganese-rich slag are more than or equal to 30-35 percent of Mn, more than or equal to 28-32 percent of SiO2, less than or equal to 15-18 percent of AL2O3, less than or equal to 1.5 percent of S, less than or equal to 0.05 percent of P, less than or equal to 1 percent of Fe and less than or equal to 0.35-0.40 percent of R3. Finally, the furnace entering manganese is more than or equal to 18 percent, the furnace entering iron is 35-40 percent, the slag-iron ratio is more than or equal to 1.0-1.6t/t, the manganese grade of the manganese-rich slag is 30-40 percent, the manganese content of the byproduct high manganese pig iron is 5-6 percent, the sulfur is less than 0.02 percent, the physical heat is 1280-. The converter smelting process adopted by the high manganese molten iron has great influence on process control and midpoint control in production, particularly the temperature rises sharply in the early silicomanganese oxidation period, which easily causes large slag overflow of the converter and large splashing, and the unreasonable control of the flux and the gun position not only causes the increase of metal loss, but also cannot control the smelting difficulty. The manganese content in the high manganese molten iron is about 5 percent on average, 40 percent of manganese enters slag in the early oxidation period, and the end point manganese residue is 20 percent. According to the manganese-rich slag furnace, manganese-rich slag with the manganese grade of more than 35% is produced by a charging structure (the charged manganese is equal to or more than 18% and the iron is equal to or more than 35%) according to the invention, the manganese-rich slag is naturally cooled in water-cooled slag before the furnace for 5 hours and then is pulled to a granulating workshop for granulating treatment, meanwhile, the produced high-manganese molten iron is pulled to a converter workshop through a hot metal ladle car, is uniformly mixed by an iron mixing furnace, is heated to about 1300 ℃, and is added into the converter for oxygen blowing. Primary slagging blowing: the lance position control adopts a four-section operation mode of constant-pressure rheologic lance 'low-medium-high-low', the basic lance position is 700 + 1400mm, the oxygen supply flow is reduced at the early stage, bottom blowing is carried out, a bottom blowing system is not arranged at the middle and later stages, the oxygen supply pressure is 0.6-0.9MPa, the oxygen supply intensity is 1.8-3.0m3/min.t, a flux is added before the converter is blown, the oxygen pressure is 0.65MPa, the oxygen supply intensity is about 1.8m3/min.t, the lance position is ignited at 900mm, the blast can be rapidly formed in 1-2 min, manganese Mn is rapidly and largely oxidized to form (MnO.SiO2), along with the increase of (CaO) in the slag, (MnO.SiO2) +2(CaO) + (MnO), the lance position is lifted to about 1300mm after the blast is carried out for 1-3 min, the temperature rise is inhibited, the content of (FeO) in the slag is improved, the [ Mn ] + (FeO) is promoted to react with the FeO) (MnO) in the slag, the slag disk is lifted to carry out the slag disk after 5-7 min, the slag pan is immediately transported to a slag treatment room for natural cooling to obtain manganese-rich slag with chemical components of MnO 38-45%, SiO 223-27%, MgO4.5%, CaO 12-16% and FeO 16-18%; secondary slagging blowing: carrying out secondary slagging blowing, after blowing at the middle lance position of 1100-1200mm of the blowing lance position for 2 minutes, lifting the lance to the high lance position of 1400-1500mm for 3 minutes, and then pressing the lance to 800mm deep blowing and carbon-pulling operation according to the flame at the furnace mouth, so as to improve the end point residual manganese Mn content, mainly improving the residual manganese content in molten steel by improving the end point temperature, reducing the FeO content in slag, improving the end point carbon C content and other measures, advancing the carbon-pulling time, prolonging the carbon-pulling time (40-60S), improving the end point residual manganese, reducing the alloy dosage during alloying, obtaining the residual manganese rate in steel of more than 20 percent, obtaining the MnO with 1.0-1.4 percent of residual manganese and 0.15-0.2 percent of carbon, and enriching the manganese slag of 22-27 percent; and (3) post-treatment: after the furnace is processed by semi-steel decarburization dephosphorization alloying, the continuous casting and continuous rolling treatment is carried out to form a material, and the iron removal treatment is carried out on the manganese-rich slag at the end point.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (2)

1. A process method for upgrading a manganese-rich slag smelting product structure is characterized by comprising the following steps:

s1, preparing materials for a manganese sintering process: using low-manganese high-iron high-sulfur powder Fe 35-38%, Mn 5-10%, S more than or equal to 0.4%, SiO2 more than or equal to 19%, south Africa high-iron powder Fe 24-27%, Mn 26-27.5%, AL₂O₃Sintering production is carried out on more than or equal to 3 percent of domestic high-sulfur iron concentrate powder Fe64-65 percent and more than or equal to 2.6 percent of S as production raw materials;

s2, preparing manganese-rich slag: manganese sinter produced by using a manganese sintering process comprises 13-15% of Mn, 39-45% of Fe, 60% of additive, Fe 20-23% of high-alumina manganese ore, 29-33% of Mn and AL₂O₃More than or equal to 9 percent, adding 30 percent of additive, low-manganese high-iron ore Mn5-10 percent, Fe35-38 percent, S more than or equal to 0.5 percent, P more than or equal to 0.3 percent and adding 10 percent to produce manganese-rich slag as production raw materials;

s3, manganese-rich slag whole grain and high-manganese molten iron transfer: naturally cooling the produced manganese-rich slag in the water-cooled slag in front of the converter for 5 hours, and then drawing the manganese-rich slag to a granulating workshop for granulating treatment, simultaneously drawing the produced high-manganese molten iron to a converter workshop through a hot metal ladle car, uniformly mixing the high-manganese molten iron in a mixer furnace, heating to about 1300 ℃, adding the high-manganese molten iron into the converter for oxygen blowing;

s4, matching the structural ingredients of the steel materials entering the furnace: the molten iron uses the physical heat of 1250 ℃ and 1300 ℃, and the content of C is as follows: 4.2-4.5%, Si: 0.1-0.3%, Mn: 5-6%, S: 0.01-0.02%, P: 0.12-0.150%, and the proportion is as follows: the scrap steel ratio is 40-50%, the high manganese molten iron consumption is 700 plus 800kg/t, the lime is 65kg/t, the dolomite is 30kg/t, and the comprehensive manganese Mn of the steel material fed into the furnace is 3-4%;

s5, primary slagging blowing: the basic lance position is 700-1400mm, the oxygen supply flow is reduced at the early stage, open bottom blowing is carried out, a bottom blowing system is not arranged at the middle and later stages, the oxygen supply pressure is 0.6-0.9MPa, the oxygen supply strength is 1.8-3.0m3/min.t, a flux is added before the converter is opened, the oxygen pressure is 0.65MPa, the oxygen supply strength is about 1.8m3/min.t, the lance position is 900mm, the furnace is started for 1-2 minutes to rapidly form slag, the lance position is lifted to 1300mm after the converter is opened for 1-3 minutes, the slag is turned over to a slag pan after 5-7 minutes, the slag pan is immediately conveyed to a slag treatment room for natural cooling, and the chemical components of MnO38-45 percent and SiO are obtained₂23-27 percent of manganese-rich slag, 4.5 percent of MgO4, 12-16 percent of CaO, 16-18 percent of FeO;

s6, secondary slagging blowing: carrying out secondary slagging blowing, after blowing at the middle lance position of 1100-1200mm of the blowing lance position for 2 minutes, lifting the lance to the high lance position of 1400-1500mm for blowing for 3 minutes, and then pressing the lance to 800mm deep carbon blowing according to the flame at the furnace mouth, so as to improve the end point temperature, obtain the residual manganese rate in the steel of more than 20 percent, obtain semi-steel with 1.0-1.4 percent of residual manganese and 0.15-0.2 percent of carbon, and MnO22-27 percent of manganese-rich slag;

s7, post-processing: after the furnace is processed by semi-steel decarburization dephosphorization alloying, the continuous casting and continuous rolling treatment is carried out to form a material, and the iron removal treatment is carried out on the manganese-rich slag at the end point.

2. The process for upgrading the structure of a manganese-rich slag smelting product according to claim 1, wherein a flux is added in the secondary slagging and blowing process to keep the end point alkalinity of the secondary slagging and blowing process at 2.5-3.0.

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