Distribution equilibria and slag chemistry of DON smelting

Equilibrium fluxing chemistry and metal value distributions of nickel matte smelting in the one-step direct nickel matte technology have been determined experimentally at 1350–1450°C in MgO-bearing iron silicate slags at silica saturation. The aim was to approach the detailed smelting chemistry at typical concentrations 2.5–10?wt-% iron in MgO-bearing iron silicate slags at silica saturation by quenching and X-ray microanalysis. The results obtained under controlled P(O₂) and P(S₂) as well as constant P(SO₂)?=?0.1?atm show that copper and nickel solubilities in the slag as well as matte-to-slag distributions favour matte when the slag is modified by magnesia. At the same time, along with increasing magnesia content of the slag, its iron activity is affected by the dissolution of MgO in the slag, and iron concentration of the formed nickel matte is lowered considerably, and its sulphur concentration increased at constant oxygen and sulphur pressures of the gas phase.     

Thermodynamics of Arsenic in FeOx-CaO-SiO<Subscript>2</Subscript> Slags

The distribution of arsenic between calcium ferrite slag and liquid silver (wt pct As in slag/ wt pct As in liquid silver) with 22 wt pct CaO and between iron silicate slag with 24 wt pct SiO₂ and calcium iron silicate slags was measured at 1573 K (1300 °C) under a controlled CO-CO₂-Ar atmosphere. For the calcium ferrite slags, a broad range of oxygen partial pressure (10^–11 to 0.21 atm) was covered, whereas for the silicate slags, the oxygen partial pressure was varied from 10^–9 to 3.1 × 10^–7 atm. The measured relations between the distribution ratio of As and the oxygen partial pressure indicates that the oxidation state of arsenic in these slags is predominantly As³⁺ or AsO_1.5. The measured distribution ratio of arsenic between the calcium ferrite slag and the liquid silver was about an order of magnitude higher than that of the iron silicate slag. In addition, an increasing concentration of SiO₂ in the calcium-ferrite-based melts resulted in decreases in the distribution of arsenic into the slag. Through the use of measured equilibrium data on the arsenic content of the metal and slag in conjunction with the composition dependent on the activity of arsenic in the metal, the activity of AsO_1.5 in the slags was deduced. These activity data on AsO_1.5 show a negative deviation from the ideal behavior in these slags.     

渣组成对钢水洁净度的影响

 在实验室基础上对比研究了w(CaO)/w(SiO2)为5、w(Al2O3)为25%的渣系A,w(CaO)/w(SiO2)为8、w(Al2O3)为46%的渣系B,与高强度合金结构钢液在1600 ℃条件下反应90 min后钢水洁净度的变化,研究结果表明：随着渣系由A到B,钢中总氧质量分数平均值由12.25×10-6降低到9.25×10-6,硫质量分数平均值由19×10-6降低到8.63×10-6,炉渣的硫分配系数LS由7~17增加到120~260;渣系A、渣系B与合金钢液反应后钢中夹杂物大部分是钙镁铝硅酸盐类夹杂,并且得出渣系B精炼条件下钢中这类夹杂熔点明显低于渣系A精炼条件下的此类夹杂。     

Distribution of nickel between copper-nickel and alumina saturated iron silicate slags

The solubility of nickel in slag was determined by equilibrating copper-nickel alloys with alumina-saturated iron silicate slags in an alumina crucible at 1573 K. The experiments were carried out under controlled oxygen partial pressures in the range of 10^-10 to 10^-8 atm by use of suitable CO-CO₂ gas mixtures, and at Fe/SiO₂ ratio 1.34. The results showed that nickel dissolves in slag both as Ni²⁺ (nickel oxide) and Ni‡ (nickel metal), and the relation obtained was: (Wt pct Ni in slag) = (ie33-01) The activity coefficient of nickel oxide (γ^dgNio) and distribution coefficient of nickel (A_Ni) is calculated to be 0.375 and 233.3, respectively. γ^dgNio and A_Ni are found to be independent of oxygen partial pressures. The presence of alumina increases the solubility of nickel in slags.     

Distribution of Bi Between Slags and Liquid Copper

The distribution of Bi between liquid copper and calcium ferrite slag containing 24 wt pct CaO, iron silicate slag with 25 wt pct SiO₂, and calcium iron silicate slags was measured at 1573 K (1300 °C) under controlled CO-CO₂ atmosphere. The experimental results showed that bismuth distribution is affected by the oxygen partial pressure, and bismuth is likely to exist in slags in the 2+ oxidation state, i.e., as BiO. The distribution ratio between calcium ferrite slag and metal was found to be close to that of iron silicate slag. The Bi distribution ratio was found to decrease with increasing SiO₂ and Al₂O₃ content in slag. Increasing temperature was found to decrease the Bi distribution ratio between slag and metal. Using the measured equilibrium data on Bi content of the metal and slag and composition dependence of the activity of Bi in liquid copper, the activity and hence activity coefficient of BiO in the slag was calculated. The close value of activity coefficient of BiO in both slags at the same oxygen partial pressure indicates that the CaO-BiO and SiO₂-BiO interactions are likely to be at the same level, or the FeO _x -BiO interaction is the predominant interaction for BiO in the slag. Therefore at a constant FeO _x content in the slag, the CaO-BiO and SiO₂-BiO interactions doesn’t affect \( \gamma_{\text{BiO}} \) significantly.     

A thermodynamic study of silica-saturated iron silicate slags in equilibrium with liquid copper

The thermodynamic properties of silica-saturated iron silicate slags in equilibrium with liquid copper have been studied from oxygen partial pressure measurements in the temperature range from 1490 to 1580 K by means of a solid electrolyte galvanic cell. The following cells were used: Pt, Ni-NiO/O⁼/slag-Cu(l), Cr₂O₃, Pt; Pt, Fe-FeO/O⁼/slag-Cu(Fe sat.), Fe. A strong correlation was found between oxygen pressure and the copper content of the slag; the copper content increased from less than 1 pct near iron saturation to about 4 pct at an oxygen partial pressure of 7.2 x 10^?3 Pa. A similar correlation was found between the ferric iron/total iron ratio and the oxygen pressure. The oxygen content in liquid copper decreased with increasing iron content in liquid copper and increased slightly near iron saturation. This behavior could be explained qualitatively by using the standard free energy of formation of FeO and the activities of components.     

焦炉煤气自重整炉气成分与温度变化规律研究

 通过CH4 H2 CO H2O CO2 O2煤气体系的热力学模拟计算,对焦炉煤气自重整技术进行了研究。结果表明：高温、高CH4含量以及低压有利于焦炉煤气自重整。在配氧量14％,反应温度850～900 ℃,体系压力为0.3 MPa的条件下,对焦炉煤气进行自重整,则还原气平衡态组分中的氢气的体积分数可由60.0％提高到71.5％,CO体积分数可由8.0％提高到23.1％;气体的还原势为97.2％,还原气体总量约增加33％。     

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.     

On the Dissolution Behavior of Sulfur in Ternary Silicate Slags

Sulfur dissolution behavior, in terms of sulfide capacity (C _S), in ternary silicate slags (molten oxide slags composed of MO – NO – SiO₂, where M and N are Ca, Mn, Fe, and Mg), is discussed based on available experimental data. Composition dependence of the sulfur dissolution, at least in the dilute region of sulfur, may be explained by taking into account the cation–anion first-nearest-neighbor (FNN) interaction (stability of sulfide) and the cation–cation second-nearest-neighbor (SNN) interaction over O anion (oxygen proportions in silicate slags). When the Gibbs energy of a reciprocal reaction MO + NS = MS + NO is positive, the sulfide capacity of slags with virtually no SiO₂ or low SiO₂ concentration decreases as the concentration of MO increases. However, in some slags, as SiO₂ concentration increases, replacing NO by MO at a constant SiO₂ concentration may increase sulfide capacity when the basicity of NO is less than that of MO. This phenomenon is observed as rotation of iso-C _S lines in ternary silicate slags, and it is explained by simultaneous consideration of the stability of sulfide and oxygen proportions in the silicate slags. It is suggested that a solution model for the prediction of sulfide capacity should be based on the actual dissolution mechanism of sulfur rather than on the simple empirical correlation.     

Al2O3对酒钢低铝渣黏度的影响及热力学分析

为进一步分析Al2O3含量对低铝渣黏度的影响,以酒钢高炉渣成分为基础,通过试验和FactSage热力学软件分别研究了不同Al2O3含量炉渣的黏度、液相线温度、活度和冷却结晶过程的物相变化。结果表明,在本试验的低铝渣范围内,随Al2O3含量增加,炉渣黏度增大,在1 450 ℃以上黏度低于0.45 Pa·s,炉渣流动性和稳定性良好。Al2O3活度随Al2O3含量的增加而增大,相反,SiO2活度降低也证明炉渣聚合度的增大。炉渣的冷却结晶过程则表明,在液相线温度以上时,炉渣黏度主要与炉渣结构的复杂程度有关;在液相线温度以下时,黏度受液相炉渣结构和固相颗粒含量的共同影响。     

Melting Characteristics of Recycling Slag in Decarburization Converter and Its Application Effects

 The steel slag in the decarburization converter is treated by the little water-spreading (LWS) and the heat-stewed (HS) methods, which is used as the furnace burden of the dephosphorization converter. The slag characteristics by the LWS and the HS methods and its application effects as the furnace burden are researched. The results show the moisture content in the HS slag is higher than that of the LWS slag. There is higher total iron content in the HS and the LWS slags and almost same melting point. The dicalcium silicate content in the LWS slag is higher than that in the HS slag. The tricalcium silicate in the LWS slag is lower than that in the HS slag. There are a lot of calcium ferrite in the LWS and the HS slags, which is beneficial to dephosphorization and slag melting. The LWS and the HS slags are added to dephosphorization converter each charge by 3 or 6 t. The results show that the saving lime is 0. 7-1. 0 t for each charge. The petrographic constitute of final slag for the dephosphorization converter by adding the LWS and the HS slags is dicalcium silicate, RO phase and glass phase. There are a little calcium ferrite phase in the LWS slag, which is helpful to dephosphorization. So there are better dephosphorization effects for the LWS and HS slags.     

Enrichment of Fe‐Containing Phases and Recovery of Iron and Its Oxides by Magnetic Separation from BOF Slags

Steel slag normally contains a large amount of iron and its oxides. Therefore, it is a potential renewable resource in case of inadequate iron ore supply. To recover the metals from steel slag, two types of BOF slags were remelted at 1873 K. The liquid slags were cooled using four types of cooling conditions, namely, water granulation, splashing, air cooling, and furnace cooling, to investigate the influence of cooling rate on mineral components, especially the enrichment behavior of Fe‐containing minerals. Subsequently, wet magnetic separation was conducted to examine the relations between iron recovery ratio and cooling conditions. The results show that the slags under the four cooling conditions mainly contained dicalcium silicate, RO phase, Fe_tO, 2CaO(Fe,Al)₂O₃, and calcium ferrite. However, tricalcium silicate, 12CaO·7Al₂O₃, M‐A spinel, and free CaO and MgO were occasionally observed. The amount of glass matrix decreased, the Fe‐containing minerals increased, and the minerals more fully crystallized when the cooling rate of the liquid slag was decreased. From granulation to furnace cooling of the slags, the iron content in the recovered concentrate and the iron recovery ratio both increased. This result is in agreement with the findings on phase transformation through SEM analysis.     

利用炼钢渣来增殖海藻的初探

在钢铁生产过程中产生大量的废渣、排放大量的CO2;大气中CO2气体的增多造成温室效应,使得全球气温升高。转炉渣中含有对藻类植物生长有益的营养元素,如果可以利用转炉渣作为营养源来增殖藻类固定CO2,既利用了钢渣,又能够减少大气中的CO2。研究用1号炉渣和2号转炉渣对于扁胞藻进行了一级培养和对螺旋藻进行了一级、二级培养。结果表明,加入转炉渣可以增殖扁胞藻和螺旋藻;在螺旋藻的一级培养中,1号转炉渣的最佳加入量为0.4 g/L,2号转炉渣为0.06 g/L;同时要考虑到加入转炉渣后透光度对海藻生长的影响。     

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％.     

Ligand field absorption spectra of quenched MnO−SiO2-Base slags equilibrated with various oxygen and sulfur pressures

Absorption spectra in the visible range have been measured on quenched, glassy MnO?SiO₂ slags, equilibrated with various oxygen and sulfur pressures at 1350°C. The absorption peaks are due to the electron transitions between different energy levels of 3d shell of divalent manganese cation Mn²⁺. The charge transfer bands habe also been measured. From the positions of the peaks and the charge transfer bands, the following results are deduced: sulfur is dissolved in silicate slags predominantly as free sulfur anions but not combined in silicate anion polymers. The tetrahedral arrangement of oxygen anions around a managanese cation is more favorable than the octahedral at higher oxygen and sulfur pressures and smaller CaO content. Electronic conduction in slags, generally very slight compared with ionic conduction, will be increased with increase in oxygen and sulfur pressure and decrease in CaO content. The reproducibility of the peak positions was within 50 cm^?1 or 0.006 ev and the relative error in the molar extinction coefficient was estimated to be ±15 pct. The quenching rate had no effect on the absorption spectra.     

Noninvasive determination of cardiac output in patients with severe airflow limitation

The noninvasive measurement of cardiac output (Q) by the Indirect Fick CO2-rebreathing technique requires mixed venous P CO2 (P CO2) to be determined by the rebreathing maneuver, and Pa CO2 to be estimated from end-tidal P CO2 (PET CO2). Previous work has suggested that although P CO2 can be determined, Pa CO2 cannot be accurately estimated in patients with significant airflow limitation. Nineteen patients with cystic fibrosis who had severe airflow limitation (%FEV1, 29.3 +/- 7.12 SD) were studied during steady-state exercise at 50% of their measured maximal work capacity. Estimated Pa CO2 was slightly lower than Pa CO2 measured from blood samples obtained from an indwelling arterial catheter (measured: 45.2 +/- 4.92; estimate: 42.7 +/- 5.68 mm Hg). To calculate arterial blood content, the values derived from Pa CO2, pH, hemoglobin (Hb), and O2 saturation were compared with those derived from PET CO2 and O2 saturation, where (1) pH was assumed to be 7.40 and Hb was measured, and (2) pH was assumed to be 7.40 and Hb was assumed to be 15 g/dl (measured mean pH, 7.34; Hb, 14.4 g/dl). No difference in arterial CO2 content was seen between the three methods (measured: 47.53 +/- 5.17; estimate 1: 49.57 +/- 6.58; estimate 2: 49.12 +/- 6.61 ml/100 ml). As pH and Hb can also affect mixed venous CO2 content, the effect on Q was also assessed. Both estimates fit closely with measured Q (r2=0.77 and 0.76), with intercepts not different from zero and slopes not different from 1, and coefficients of variation of 13.5 and 14.6%. When viewed with regard to the confidence intervals for Q as a function of O2 consumption, Q was altered to a minor extent. We conclude that the use of PET CO2 to estimate Pa CO2 can give reasonable values for Q determined noninvasively in patients with severe airflow limitation.     

低碳易切削钢LF炉精炼渣控制工艺

与还原渣相比,易切削钢LF精炼渣具有控氧、低脱硫率、低脱磷率的冶金功能特点。该类渣中须保持一定比例的FeO、MnO,低碱度,渣量适当并能充分吸附钢中A12O3、硅酸盐夹杂物。合适的精炼渣成分(质量分数,%)为:CaO 30~40,Al2O310~25,FeO 2~6,MnO 10~25,SiO210~20,MgO 4~8。该精炼渣的平均脱硫率为11.7%,平均LP为0.56;钢中B类夹杂物为0~1.0,C类夹杂物为0~1.5。     

低硅CaO-Al2O3渣对铝镁质浇注料的侵蚀

低密度高强化是钢铁材料的重要发展方向.由于低密度高强钢冶炼用低硅CaO-Al2O3系炉渣会不可避免地与现行铝镁质耐火材料发生反应,严重影响钢的安全高效熔炼及其品质提升.针对这一问题,采用静态坩埚法开展铝镁质浇注料的抗低硅CaO-Al2O3渣蚀实验,探究Al2O3含量变化对耐火材料渣蚀的影响规律,得到以下结论:低硅CaO...     

Effect of slag composition on steel cleanliness in interstitial-free steel

Ladle slag affects steel cleanliness at the end of the Ruhrstahl-Hereaeus (RH) and holding process.The relationship between composition of ladle slag, total oxygen (TO) and inclusions was investigated using X-ray fluorescence (XRF), infrared absorption, and SEM+EDS methods.The results indicate that TO in steel at the end of RH increases linearly with increasing FeO content in slag.TO is lower when wCaO/wAl2 O3 (C/A)=1.5-2.0 than that of C/A=1.0-1.4 under an approximate content of FeO.During the holding process, irregular Al2 O3 inclusions are newly generated due to slag reoxidation.Additionally, Al2 O3-Tix O inclusions are newly generated in the steel when the content of FeO is higher.By combining experimental and thermodynamic calculation results, it is determined that the slag has a good melting property within the zone of C/A=1.2-1.8 and adsorption capacity of Al2 O3 when the content of SiO2 in slag is controlled at 4%-6%.The increase in the C/A ratio and the decrease of FeO content in slag can slow down the reoxidation rate.