通钢通过65 t Consteel电弧炉-65 t LF-150 mm×150 mm方坯连铸流程生产40Cr合金钢。检验结果表明,通过LF精炼,40Cr钢水中的氧含量由精炼前227×10-6降至35×10-6;而连铸时中间包钢中的氧含量增加至51×10-6,铸坯的氧...通钢通过65 t Consteel电弧炉-65 t LF-150 mm×150 mm方坯连铸流程生产40Cr合金钢。检验结果表明,通过LF精炼,40Cr钢水中的氧含量由精炼前227×10-6降至35×10-6;而连铸时中间包钢中的氧含量增加至51×10-6,铸坯的氧含量为54×10-6。因此,进一步预防钢水从钢包至中间包及中间包内钢水的二次氧化和去除钢中大型夹杂物,是提高钢水洁净度和降低[O]的关键步骤。展开更多
This study analyzes the feasibility of using stainless steel electric arc furnace （EAF） slag as composite cement admixture and the risk of leaching-out of heavy metals. The results show that the stainless steel EAF ...This study analyzes the feasibility of using stainless steel electric arc furnace （EAF） slag as composite cement admixture and the risk of leaching-out of heavy metals. The results show that the stainless steel EAF slag, mainly made up of Ca2 SiO4, Ca3 Mg （ SiO4 ） 2, some Cr-containing minerals and in small particle size, is easily ground and has cementitious activity. EAF slag, when used as cement admixture, can be added with a maximum percentage of 32%. It can meet the strength requirements of the standard P · C 32.5 cement. When the mixing percentage is decreased to 25 % , the strength of the cement can be increased to that of P · C 42.5 cement. Other main quality indexes of composite cement, such as the setting time and stability, also satisfy standard requirements. The results also show that most of the heavy metals in the stainless steel EAF slag exist in a stable speciation. The concentration of heavy metals that leach out from the stainless steel EAF slag and the composite cement products is far lower than the standard limit of hazardous wastes. The main heavy metal, chromium, exists as less hazardous trivalent chromium. Therefore, the risk of heavy metals leaching out from the stainless steel EAF slag is low. The internal exposure index （IRa） and the external exposure index （Iγ） of the stainless steel EAF slag are both lower than 1.0, satisfying the standard requirements of the state for the radionuclides of building materials. Therefore, stainless steel EAF slag can be safely used as admixture to produce composite cement.展开更多
Reducing steel slag （RSS） was mainly acquired from five electric-arc furnace （EAF） steelmaking plants （among them, the products of two plants were carbon steel and those of other plants were stainless steel） for...Reducing steel slag （RSS） was mainly acquired from five electric-arc furnace （EAF） steelmaking plants （among them, the products of two plants were carbon steel and those of other plants were stainless steel） for research tests. The chemical properties, compound compositions, activities and contents of main expansive compounds were tested. The results showed that the field sampled RSS had a very high crystallinity and hydraulicity with main chemical compositions close to those of Portland cement. It can be known from the study that in case of C/S ratio higher than 2.0, the main compound compositions are C2S, C3S, C2F and f-CaO. However, after the RSS was stored for six months, an obvious variation occurred with potential pre-hydration in RSS, where the SO3 content was slightly reduced and the compressive activity index was obviously higher than that at the 28th day.展开更多
Decarbonization and decontamination of the iron and steel industry(ISI),which contributes up to 15%to anthropogenic CO_(2) emissions(or carbon emissions)and significant proportions of air and water pollutant emissions...Decarbonization and decontamination of the iron and steel industry(ISI),which contributes up to 15%to anthropogenic CO_(2) emissions(or carbon emissions)and significant proportions of air and water pollutant emissions in China,are challenged by the huge demand for steel.Carbon and pollutants often share common emission sources,indicating that emission reduction could be achieved synergistically.Here,we explored the inherent potential of measures to adjust feedstock composition and technological structure and to control the size of the ISI to achieve carbon emission reduction(CER)and pollution emission reduction(PER).We investigated five typical pollutants in this study,namely,petroleum hydrocarbon pollutants and chemical oxygen demand in wastewater,particulate matter,SO_(2),and NO_(x) in off gases,and examined synergies between CER and PER by employing cross elasticity for the period between 2022 and 2035.The results suggest that a reduction of 8.7%-11.7%in carbon emissions and 20%-31%in pollution emissions(except for particulate matter emissions)could be achieved by 2025 under a high steel scrap ratio(SSR)scenario.Here,the SSR and electric arc furnace(EAF)ratio serve critical roles in enhancing synergies between CER and PER(which vary with the type of pollutant).However,subject to a limited volume of steel scrap,a focused increase in the EAF ratio with neglection of the available supply of steel scrap to EAF facilities would lead to an increase carbon and pollution emissions.Although CER can be achieved through SSR and EAF ratio optimization,only when the crude steel production growth rate remains below 2.2%can these optimization measures maintain the emissions in 2030 at a similar level to that in 2021.Therefore,the synergistic effects between PER and CER should be considered when formulating a development route for the ISI in the future.展开更多
This paper presents the improvements on equipment and process technologies of Baosteel EAF Bloom Caster Production Line.By using the new VOD equipment,super low carbon super 13Cr was successfully made;By applying and ...This paper presents the improvements on equipment and process technologies of Baosteel EAF Bloom Caster Production Line.By using the new VOD equipment,super low carbon super 13Cr was successfully made;By applying and developing the Soft Reduction technology,very good results were achieved on high quality steel grades such as tire cord steel,bear steel,hi-alloy steel;the ladle Anti-Slag Detector is normally applied,based on the detail analysis during the performance test period,the Detector gives out slag entrapment alarms 7-9 s average before slag flows into tundish.By optimizing production control points of each key process,great achievements are realized on high quality steel grades such as tire cord steel,bear steel,hi-alloy steel and hi-S/Al steel,etc.Some achievements and technical indices are presented,too.展开更多
The abnormal corrosion of hot iron ladles was investigated.The performance,the composition and the structure of bricks for hot iron ladles were analyzed.The results show that(1)compared with the alumina-silicon carbid...The abnormal corrosion of hot iron ladles was investigated.The performance,the composition and the structure of bricks for hot iron ladles were analyzed.The results show that(1)compared with the alumina-silicon carbide-carbon bricks for the ladle bottom,those for the ladle wall have more pyrophyllite and the Al2O3 content of 36.32 mass%;their bulk density,apparent porosity and cold compressive strength are lower than the requirement of industry standard;they have poor anti-oxidation performance and are oxidized to form a porous layer during service,which loosens the brick lining structure thus leading to fracture,local wear and structural damage of bricks;(2)without preheating,steel scraps are not completely melted,resulting in slag or steel attachment at the mouth or the bottom of ladles thus increasing damage of ladles;(3)and the residual bricks react with the attached slag to form low melting point phases affecting their hot properties.The refractories for the lining of hot iron ladles must be improved in combination with process changes,not entirely by raw materials replacement to reduce costs.展开更多
The aim of this study was to determine the quality of rebar produced from recycled scrap metal collected throughout the country,and imported rebar sold in the Republic of Guinea.To do this,the samples were subjected t...The aim of this study was to determine the quality of rebar produced from recycled scrap metal collected throughout the country,and imported rebar sold in the Republic of Guinea.To do this,the samples were subjected to various mechanical tests involving traction,bending and microscopic analysis.In the Lambanyi and Casse Sonfonia samples,all the tensile strength values for diameters 12,14 and 16 were above 550 MPa.Conversely,the iron samples from Baillobaye and the 10 mm diameters of the samples from Casse Sonfonio and Lambanyi have less appreciable values.The limits of elasticity were determined.The various values found vary more or less from the conventional yield strength of the NF A35-016 reference supplied by CBITEC,which is 500 MPa.Microscopic analysis gives us an insight into the internal structure of the iron samples used.This study may provide the company and the vendors with an alternative for their improvements.展开更多
26CrMoNbTiB钢由45 t EAF-LF(VD)-Φ80～180mm管坯HCC流程冶炼。该钢各工序的洁净度试验结果表明,LF-VD后钢中氧含量为(8～18)×10^(-6),平均夹杂物数量最低为2.31个/mm^2,连铸坯平均夹杂物数量为3.66个/mm^2,≥50μm大型夹杂物平...26CrMoNbTiB钢由45 t EAF-LF(VD)-Φ80～180mm管坯HCC流程冶炼。该钢各工序的洁净度试验结果表明,LF-VD后钢中氧含量为(8～18)×10^(-6),平均夹杂物数量最低为2.31个/mm^2,连铸坯平均夹杂物数量为3.66个/mm^2,≥50μm大型夹杂物平均含量为4.08 mg/10 kg。加强钢包到中间包长水口的密封保护和采用钢包下渣检测装置,提高中间包容量和采用挡渣墙是进一步提高铸坯洁净度的关键工艺措施。展开更多
文摘通钢通过65 t Consteel电弧炉-65 t LF-150 mm×150 mm方坯连铸流程生产40Cr合金钢。检验结果表明,通过LF精炼,40Cr钢水中的氧含量由精炼前227×10-6降至35×10-6;而连铸时中间包钢中的氧含量增加至51×10-6,铸坯的氧含量为54×10-6。因此,进一步预防钢水从钢包至中间包及中间包内钢水的二次氧化和去除钢中大型夹杂物,是提高钢水洁净度和降低[O]的关键步骤。
文摘This study analyzes the feasibility of using stainless steel electric arc furnace （EAF） slag as composite cement admixture and the risk of leaching-out of heavy metals. The results show that the stainless steel EAF slag, mainly made up of Ca2 SiO4, Ca3 Mg （ SiO4 ） 2, some Cr-containing minerals and in small particle size, is easily ground and has cementitious activity. EAF slag, when used as cement admixture, can be added with a maximum percentage of 32%. It can meet the strength requirements of the standard P · C 32.5 cement. When the mixing percentage is decreased to 25 % , the strength of the cement can be increased to that of P · C 42.5 cement. Other main quality indexes of composite cement, such as the setting time and stability, also satisfy standard requirements. The results also show that most of the heavy metals in the stainless steel EAF slag exist in a stable speciation. The concentration of heavy metals that leach out from the stainless steel EAF slag and the composite cement products is far lower than the standard limit of hazardous wastes. The main heavy metal, chromium, exists as less hazardous trivalent chromium. Therefore, the risk of heavy metals leaching out from the stainless steel EAF slag is low. The internal exposure index （IRa） and the external exposure index （Iγ） of the stainless steel EAF slag are both lower than 1.0, satisfying the standard requirements of the state for the radionuclides of building materials. Therefore, stainless steel EAF slag can be safely used as admixture to produce composite cement.
文摘Reducing steel slag （RSS） was mainly acquired from five electric-arc furnace （EAF） steelmaking plants （among them, the products of two plants were carbon steel and those of other plants were stainless steel） for research tests. The chemical properties, compound compositions, activities and contents of main expansive compounds were tested. The results showed that the field sampled RSS had a very high crystallinity and hydraulicity with main chemical compositions close to those of Portland cement. It can be known from the study that in case of C/S ratio higher than 2.0, the main compound compositions are C2S, C3S, C2F and f-CaO. However, after the RSS was stored for six months, an obvious variation occurred with potential pre-hydration in RSS, where the SO3 content was slightly reduced and the compressive activity index was obviously higher than that at the 28th day.
基金supported by the National Key Research and Development Program of China(2019YFC1904800)the National Natural Science Foundation of China(72274105).
文摘Decarbonization and decontamination of the iron and steel industry(ISI),which contributes up to 15%to anthropogenic CO_(2) emissions(or carbon emissions)and significant proportions of air and water pollutant emissions in China,are challenged by the huge demand for steel.Carbon and pollutants often share common emission sources,indicating that emission reduction could be achieved synergistically.Here,we explored the inherent potential of measures to adjust feedstock composition and technological structure and to control the size of the ISI to achieve carbon emission reduction(CER)and pollution emission reduction(PER).We investigated five typical pollutants in this study,namely,petroleum hydrocarbon pollutants and chemical oxygen demand in wastewater,particulate matter,SO_(2),and NO_(x) in off gases,and examined synergies between CER and PER by employing cross elasticity for the period between 2022 and 2035.The results suggest that a reduction of 8.7%-11.7%in carbon emissions and 20%-31%in pollution emissions(except for particulate matter emissions)could be achieved by 2025 under a high steel scrap ratio(SSR)scenario.Here,the SSR and electric arc furnace(EAF)ratio serve critical roles in enhancing synergies between CER and PER(which vary with the type of pollutant).However,subject to a limited volume of steel scrap,a focused increase in the EAF ratio with neglection of the available supply of steel scrap to EAF facilities would lead to an increase carbon and pollution emissions.Although CER can be achieved through SSR and EAF ratio optimization,only when the crude steel production growth rate remains below 2.2%can these optimization measures maintain the emissions in 2030 at a similar level to that in 2021.Therefore,the synergistic effects between PER and CER should be considered when formulating a development route for the ISI in the future.
文摘This paper presents the improvements on equipment and process technologies of Baosteel EAF Bloom Caster Production Line.By using the new VOD equipment,super low carbon super 13Cr was successfully made;By applying and developing the Soft Reduction technology,very good results were achieved on high quality steel grades such as tire cord steel,bear steel,hi-alloy steel;the ladle Anti-Slag Detector is normally applied,based on the detail analysis during the performance test period,the Detector gives out slag entrapment alarms 7-9 s average before slag flows into tundish.By optimizing production control points of each key process,great achievements are realized on high quality steel grades such as tire cord steel,bear steel,hi-alloy steel and hi-S/Al steel,etc.Some achievements and technical indices are presented,too.
文摘The abnormal corrosion of hot iron ladles was investigated.The performance,the composition and the structure of bricks for hot iron ladles were analyzed.The results show that(1)compared with the alumina-silicon carbide-carbon bricks for the ladle bottom,those for the ladle wall have more pyrophyllite and the Al2O3 content of 36.32 mass%;their bulk density,apparent porosity and cold compressive strength are lower than the requirement of industry standard;they have poor anti-oxidation performance and are oxidized to form a porous layer during service,which loosens the brick lining structure thus leading to fracture,local wear and structural damage of bricks;(2)without preheating,steel scraps are not completely melted,resulting in slag or steel attachment at the mouth or the bottom of ladles thus increasing damage of ladles;(3)and the residual bricks react with the attached slag to form low melting point phases affecting their hot properties.The refractories for the lining of hot iron ladles must be improved in combination with process changes,not entirely by raw materials replacement to reduce costs.
文摘The aim of this study was to determine the quality of rebar produced from recycled scrap metal collected throughout the country,and imported rebar sold in the Republic of Guinea.To do this,the samples were subjected to various mechanical tests involving traction,bending and microscopic analysis.In the Lambanyi and Casse Sonfonia samples,all the tensile strength values for diameters 12,14 and 16 were above 550 MPa.Conversely,the iron samples from Baillobaye and the 10 mm diameters of the samples from Casse Sonfonio and Lambanyi have less appreciable values.The limits of elasticity were determined.The various values found vary more or less from the conventional yield strength of the NF A35-016 reference supplied by CBITEC,which is 500 MPa.Microscopic analysis gives us an insight into the internal structure of the iron samples used.This study may provide the company and the vendors with an alternative for their improvements.
文摘26CrMoNbTiB钢由45 t EAF-LF(VD)-Φ80～180mm管坯HCC流程冶炼。该钢各工序的洁净度试验结果表明,LF-VD后钢中氧含量为(8～18)×10^(-6),平均夹杂物数量最低为2.31个/mm^2,连铸坯平均夹杂物数量为3.66个/mm^2,≥50μm大型夹杂物平均含量为4.08 mg/10 kg。加强钢包到中间包长水口的密封保护和采用钢包下渣检测装置,提高中间包容量和采用挡渣墙是进一步提高铸坯洁净度的关键工艺措施。
