硫含量对KR脱硫渣中硫赋存状态的影响

KR脱硫渣中的CaO是转炉冶炼工艺中重要的造渣原料,将其回用于钢铁冶炼工艺可降低冶金企业的CaO原料消耗,减少企业KR脱硫渣堆积量,节约企业冶炼的经济成本.KR脱硫渣中的2CaO·SiO2 (C2S)在转炉脱磷冶炼过程中可与炉渣中的磷形成稳定的2CaO· SiO2-3CaO· P2O5固溶体,提高磷在渣中的稳定性.将K...     

电渣重熔过程中渣成分变化及钢中氧含量预测

利用XRF和XRD技术分析了电渣重熔过程中不同时间所取渣样的化学成分和物相结构。XRF分析得到电渣重熔过程中渣中Al2O3、CaF2、CaO、SiO2、FeO等成分含量随熔炼时间的动态变化。XRD分析表明:凝固的渣中存在11CaO·7Al2O3·CaF2、12CaO·7Al2O3、CaSiO3等高熔点物质,导致炉渣性质发生变化。根据熔渣化学成分,参考CaF2-CaO-Al2O3渣系的等电导率图和等黏度图,得到了电渣的比电阻和黏度随冶炼时间的变化情况。采用炉渣结构共存理论建立了温度为1 923和1 973K时与渣中Al2O3平衡的钢液中[Al]-[O]平衡关系图。计算结果显示,针对实验研究的钢种,当钢中酸溶铝含量w[Al]s在0.000 1%~1%范围内时,钢液中溶解氧含量随着w[Al]s的增加先减小后增大,当钢中w[Al]s达到0.25%时,钢液中w[O]最小。在实验条件下,因渣成分变化导致的钢中w[O]的波动范围是0.25×10-6~0.48×10-6。     

The effect of carbon content on the rate of reduction of FeO in slag relevant to iron smelting

In the iron smelting, or bath smelting, process the tapped metal contains high amounts of sulfur and the slag contains high amounts of FeO, relative to blast furnace slag. After tapping, the FeO can be further reduced by carbon in the metal, which will also lead to better desulfurization. Although there have been many studies of the reaction of carbon in iron with FeO in slag, discrepancies exist with regards to the effect of carbon in iron on the rate of FeO reduction in slag, which is the subject of this study. Experiments were conducted at 1723 K, using a slag with basicity close to one with an FeO mass content of 5 %. The rate of reduction was measured using a pressure increase technique. For moderate and high sulfur contents, as in the case of iron smelting, the rate is primarily controlled by the dissociation of CO₂ on the surface of the molten iron. Furthermore, if the effect of carbon on sulfur is taken into account, for the range of carbon mass contents of 2 to 4.5 %, there is no effect of the carbon level on the rate of FeO reduction. At low sulfur contents it was found that there is considerable slag foaming, which inhibits mass transfer of FeO in the slag, and significantly reduces the rate. Even when there is no slag foaming at low sulfur contents, mass transfer of FeO in the slag can influence the rate of FeO reduction.     

KR脱硫渣的综合利用现状及其氧化去硫研究进展

KR脱硫的渣资源化利用有利于促进钢铁企业的绿色化发展.KR脱硫渣中主要成分为CaO,且含有质量分数为1.0％～2.5％的硫,直接将K R脱硫渣回用于冶炼工艺会导致钢液增硫.若能将渣中的硫脱出,可有效促进KR脱硫渣在钢铁冶炼工艺的资源化利用.因此,针对当前KR脱硫渣综合利用存在的问题,总结分析有关CaS氧化过程的热力学和...     

A New Technology for Copper Slag Reduction to Get Molten Iron and Copper Matte

The change of iron composition as well as the removal of copper from iron was investigated in the reduction process,and a new way to deal with copper slag was proposed.The iron in copper slag exists mainly in the form of fayalite,and the copper sulfide content accounts for just about 50%.Therefore,the magnetic separation as well as grinding floatation method is not suitable,and a pyrogenic treatment on copper slag is necessary.The carburization and desulfurization process is restricted to a degree within the carbon composite pellets,and copper matte phase precipitates from copper slag in the reduction process,which is immiscible with molten iron and slag.The copper content decreases to 0.4% as the carbon content in molten iron reaches 3.84%,and the removal ratio of copper from molten iron approaches to 80%.The reduction and sulfurization process can be completed in one step,and the copper is separated from iron based on the ternary system of iron-matte-slag.     

Reduction kinetics of liquid iron oxide-containing slags by carbon monoxide

The reduction of iron oxides from liquid slags is important in the nonferrous as well as the ferrous industry. In the primary smelting of copper, the trend is to produce copper mattes with increasing contents of copper. This is accomplished by increasing the degree of oxidation, leading to more oxidized slags with higher copper contents. To recover this copper, the high magnetite content of these slags has to be reduced in a separate slag cleaning process. Laboratory reduction experiments on commercial copper slags using carbon monoxide-containing gases show that the reduction rate increases with increasing injection depth and slag temperature. The reduction rate was found to follow the relationship $$Rate(\frac{{molO}}{{m^2 \cdot s}}) = 7.9 \cdot 10^5 \cdot e^{\frac{{ - 43,300}}{{T(K)}}} \cdot p_{CO} (Pa)$$ with an activation energy of 360±20 kJ/mol.     

CaO-BaO-MgO-SiO_2-CaF_2渣系对硅锰合金脱硫的影响

采用高温硅钼炉和常规化学分析法对高硫含量的硅锰合金进行了系列脱硫研究,分析了CaO-BaO-MgOSiO2-CaF2渣系中MgO、CaO、BaO含量的变化对脱硫效果的影响。结果表明:当MgO的质量分数大于8%时,脱硫率会随着MgO含量的增加而升高。用(MgO+CaF2)代替CaO不利于脱硫;用(MgO+CaF2)代替质量分数为0~4%的BaO有利于渣系脱硫,但代替量过多时不利于脱硫。得到了最佳硅锰合金脱硫的渣系,wCaO/wBaO为1.25时脱硫率最高。     

Copper losses and thermodynamic considerations in copper smelting

A relationship between copper in slag and copper in matte during copper sulfide smelting has been derived using industrial data from 42 plants employing blast furnaces, reverberatory furnaces, flash furnaces, and Mitsubishi smelting furnaces together with the available thermodynamic equilibrium data for Cu-Fe-S-O, FeO-SiO₂, and Cu-Fe-S systems and laboratory slag-matte equilibrium information. A copper smelting diagram showing oxygen potential; sulfur potential; and copper, magnetite, and sulfur contents in slag during the smelting of different grades of copper mattes is developed for mattes containing less than 70 pct copper. The data presented can be used to determine the entrained copper losses in slag. Further, by combining the calculated value of the entrained matte with the corresponding plant data for the sulfur content of the slag, it is possible to derive the dissolved sulfur content of the slag. These calculated values were in excellent agreement with the experimentally determined sulfide capacity of fayalite slags. It is shown that there is no need to assume the presence of dissolved copper sulfide species in industrial slags. The existing equilibrium data that relate the copper content of slags to oxygen potential adequately describe the copper losses in industrial slags.     

冷却速率对KR脱硫渣中硫析出行为的影响

KR脱硫渣中主要成分(CaO)为转炉冶炼的优质造渣原料,通过氧化性气氛将渣中硫脱除后可将其用于转炉冶炼.但由于炉渣冷却制度不同,渣中硫的析出行为和赋存状态会发生变化,对炉渣氧化脱硫效果产生影响.基于此,以合成渣的形式探究冷速对KR脱硫渣中硫析出行为的影响,旨在明确KR脱硫渣中硫赋存状态及析出行为与冷却速率的关系,为后续...     

Nitrogen solubility in metallurgical slags equilibrated with Fe–Al or Fe–Ca melts

Considerations are directed to the denitrogenation potential of metallurgical slags with respect to steel melts under reducing conditions. Experiments were made to determine partition ratios of nitrogen between molten slag and iron. The investigated systems were aluminate-based slags, containing CaO, MgO, SrO, BaO, CaF₂ or ZrO₂, in equilibrium with Fe–AI melts and Ca–CaO–CaF₂ slags equilibrated with Fe–Ca melts. Denitrogenation efficiency of aluminate-based slags is comparatively low and essentially determined by oxygen potential and basicity of the slag. Denitrogenation efficiency of Ca–CaO–CaF₂ slags is much higher and is dependent on calcium activity.     

Vacuum Treatment for Simultaneous Desulphurization and Dephosphorization of Hot Metal and Molten Steel

The vacuum treatment for simultaneous desulphurization and dephosphorization of hot metal and molten steel with pre-melted CaO-based slag was carried out. For pre-treatment of hot metal, both desulphurization and dephosphorization are improved with the increase of CaO in slag, but deteriorated with the increase of CaF2 in slag. The average desulphurization and dephosphorization rate is 68.83% and 78.46 %, respectively. For molten steel, the sub-stitution of BaO for CaO in slag has minor effect on simultaneous desulphurization and dephosphorization. The desulphurization and dephosphorization rate is higher than 90 % and 50% respectively with the lowest final sulfur and phosphorus mass percent being 0. 001 2 % and 0. 010%, respectively. The overall effect of simultaneous desulphurization and dephosphorization of molten steel is better than that of hot metal.     

Kinetics of simultaneous reactions between liquid iron-carbon alloys and slags containing MnO

The oxidation rates of carbon, phosphorus, and silicon; the desulfurization rate of liquid iron; and the simultaneous reduction rate of MnO from slag were examined at 1450 °C to 1550 °C by using high carbon iron alloys and CaO-SiO₂-CaF₂ slags containing MnO and FeO. The reaction rates were well reproduced by a kinetic model describing the reaction between the slag and multicomponent iron alloys. The controlling steps applied for the reactions considered in the present kinetic simulation were as follows. The rate of decarburization is controlled by the chemical reaction at the slag-metal interface, and those of the other reactions are controlled by the transport in slag and metal phases. Both observation and simulation results showed that MnO was not a strong oxidizer compared with FeO in the slag, but was an effective component for desulfurization. The simulation results also showed that the interfacial oxygen activity using MnO-based slag was much lower than that using FeO-based slag. The apparent equilibrium constants of phosphorus and sulfur, which were obtained by the kinetic modeling of experimental results, were found to increase with increasing the (MnO + CaO)/SiO₂ ratio of the slag. The controlling step(s) of each element transport across the slag-metal interface was discussed with the aid of the kinetic model.     

镍火法熔炼高钙低硅渣提取铁的研究

镍火法冶炼的高硅酸铁渣在综合利用中还原提取铁比较困难,通过在镍熔炼渣中适当增加CaO含量、减少SiO2含量以改善后续还原提取铁的热力学条件.在对所确定的新渣型对镍锍进行分离试验后,对熔炼终渣进行物相分析和还原提取铁试验,探讨了原渣和高钙低硅新渣型还原提取铁的不同.研究结果表明,高钙低硅新渣型终渣中铁主要以Ca(Fe,Mg) Si2O6以及MgFe2O4形式存在,50％以上的Fe以MgFe2O4的形式存在,其磁性以及还原性都比原渣中的(Fe,Mg)2SiO4要好,有利于其还原.与原渣的还原性相比,在试验条件下,当wCaO/wSiO2为0.80时,其还原率由48.53％提高到了57.45％.     

The Thermodynamics of Some Transition Metals in Molten Slags

In the present paper, the thermodynamic behaviour of transition metals, such as Cr, Ti, Nb and V in molten slags is systematically analysed based on a literature survey. These metals exist in molten slags with multi valences. Oxygen partial pressure, slag basicity, total content of each transition metal, content of each component in slag, and temperature are the influential factors on their thermodynamic properties in molten slags. Higher basicity and strong oxidative atmosphere are generally favourable for the stable existence of transition‐metal ions with higher oxidation states. Temperature is a factor that is less influential than the above‐mentioned ones. For a transition metal in molten slag, the concentration ratio of ions of different valences depends on the activity coefficient ratio of their oxides. The present paper summarizes the activity studies regarding the transition metal oxides in various molten slags. For chromium and titanium oxides, information on CaO? SiO₂ based systems is involved. For titanium oxides, its thermodynamic behaviour in MnO? SiO₂ based slags is introduced. For niobium and vanadium, the information in Na₂O? SiO₂, CaO? CaF₂? SiO₂ systems is provided. Thermodynamic studies are described for Nb₂O₅? MnO? SiO₂ molten slag equilibrated with liquid iron at 1828 K.     

Evaluation of Sulfur Addition to the High Basicity Slag on the Sulfur,Aluminum, and Cleanliness of High Sulfur Al‐Killed Molten Steel

In the present work, the influence of sulfur addition to the high basicity slag on the Al‐killed molten steel with high sulfur content was investigated by using a vacuum induction furnace at 1873 K in MgO crucibles. CaO–SiO₂–Al₂O₃–MgO–CaS slags were used to study the effect of high basicity slags with different CaS contents on sulfur loss, aluminum loss, and total oxygen content in the molten steel. It is shown that the sulfur content in the molten steel decreased with the time, and the addition of CaS into the slag can reduce the sulfur loss in the molten steel. Moreover, there was a decreasing tendency of the aluminum content in the molten steel with the time, and the addition of CaS into the slag can reduce the aluminum loss in the molten steel. Total oxygen content in the molten steel first increased and then decreased with the time when no CaS was added into the slag. However, it decreased monotonically with the time when the addition of CaS was made into the slag.     

CaO-MgO-FeO-Al_2O_3-SiO_2-P_2O_5渣系与碳饱和铁液间硫分配比的热力学模型

在富氧顶吹熔融还原冶炼高磷铁矿的工艺研究中,以共存理论为基础,结合全选主元松弛迭代法,利用VB 6.0计算了CaO-MgO-FeO-Al2O3-SiO2-P2O5渣系中结构单元或离子对的质量作用浓度,并建立了该渣系与碳饱和铁液间硫分配比的热力学模型,由该模型计算的硫分配比与工艺中实测的硫分配比吻合程度较好,说明利用共存理论所建立的脱硫模型能适用在熔融还原高效脱磷熔渣。     

转炉及KR循环利用钢包热态铸余渣工艺试验

为了达到节能降耗的目的,在转炉及KR进行钢包热态铸余渣循环利用的工艺试验。对比分析了转炉及KR循环利用钢包热态铸余渣前后的成渣效果和冶金效果。结果表明,在不需要对现有装备进行改造的情况下,常规炉次每炉加入约30 kg/t的钢包热态铸余渣,可节约消耗钢铁料12 kg/t、石灰4.31 kg/t、烧结矿4.87 kg/t、氧气1.83 m3/t,缩短冶炼时间3.24 min/炉,节省冶炼成本39.43 元/t(钢),降低终点a[O]含量,提高终点脱磷率,在提高钢水质量和冶炼效率、降低炼钢成本的同时,减轻了钢包铸余渣排放对环境的污染,经济效益和社会效益良好。为减小钢包铸余渣中硫含量高对转炉冶炼效果的影响,可采用将钢包热态铸余渣返回KR进行铁水预处理的方式加以循环利用,每罐铁水中加入约27 kg/t的钢包热态铸余渣后,石灰等脱硫剂用量减少82.2%,铁水预处理时间缩短1 min,温降减少4 ℃,回磷率降低2个百分点,脱硫率达到69.4%,同样取得了良好效果。     

KR脱硫渣高温矿物组成及含硫相的析出行为

 KR脱硫渣是KR铁水预处理脱硫工艺的副产品,其磁选后尾渣中CaO质量分数大于50%。可将其用作优质造渣原料返回到转炉炼钢工艺中,降低转炉炼钢的原料消耗。但KR脱硫渣中的硫(w((S))=1.0%～2.5%)成为转炉冶炼循环利用的障碍,直接将其用于转炉冶炼会使钢中的硫含量增加。因此,根据工业KR脱硫渣的化学成分,以合成渣的形式对KR脱硫渣中矿物组成及含硫相的析出行为进行研究,旨在明确KR脱硫渣中各矿物相组成及炉渣中硫的析出行为和赋存状态,为后续通过氧化性气氛有效脱除KR脱硫渣中的硫提供理论参考。采用热力学数据库FactSage 8.0的Equilib模块对CaO-SiO₂-CaS-CaF₂基熔渣的凝固过程进行模拟,利用XRD、SEM-EDS对合成渣样品的矿物组成及微观形貌进行分析、检测。热力学计算结果表明,CaS的析晶温度为1 320 ℃,低于MeO#1相、MeO#2相及2CaO·SiO₂相的析晶温度。炉渣样品的面扫描分析结果表明,在实际凝固过程中,受残余液相黏度增大的影响炉渣中少量硫未能析出形成CaS晶体,则以非晶态的形式赋存在基质相中。KR脱硫渣主要由C₃S相、MeO#1相(CaO固溶体)、MeO#2相(MgO固溶体)、基质相和CaS相等矿物组成。炉渣中的硫主要以游离态CaS晶体形式赋存,少量以非晶态硫的形式赋存。炉渣中CaS晶粒主要沿着先析出的高熔点硅酸盐(C₃S)相边界析出。     

转炉及KR循环利用钢包热态铸余渣工艺试验

为了达到节能降耗的目的,在转炉及KR进行钢包热态铸余渣循环利用的工艺试验。对比分析了转炉及KR循环利用钢包热态铸余渣前后的成渣效果和冶金效果。结果表明,在不需要对现有装备进行改造的情况下,常规炉次每炉加入约30 kg/t的钢包热态铸余渣,可节约消耗钢铁料12 kg/t、石灰4.31 kg/t、烧结矿4.87 kg/t、氧气1.83 m3/t,缩短冶炼时间3.24 min/炉,节省冶炼成本39.43 元/t(钢),降低终点a[O]含量,提高终点脱磷率,在提高钢水质量和冶炼效率、降低炼钢成本的同时,减轻了钢包铸余渣排放对环境的污染,经济效益和社会效益良好。为减小钢包铸余渣中硫含量高对转炉冶炼效果的影响,可采用将钢包热态铸余渣返回KR进行铁水预处理的方式加以循环利用,每罐铁水中加入约27 kg/t的钢包热态铸余渣后,石灰等脱硫剂用量减少82.2%,铁水预处理时间缩短1 min,温降减少4 ℃,回磷率降低2个百分点,脱硫率达到69.4%,同样取得了良好效果。     

FeO-MgO-CaO-SiO2系炉渣电导的测定与研究

对FeO-SiO2-MgO-CaO渣系的电导率进行了测试研究。结果表明,在CaO6%,Fe/SiO2=1.2时,随着MgO含量的增加,熔渣电导率增大。MgO11%,Fe/SiO2=1.2时,电导率随CaO含量的增加而增大,当CaO含量大于6%,CaO含量的变化对电导率的影响较弱。电导率随Fe/SiO2比值增加而增大。温度增加,熔渣电导率增大。