Smelting Characteristics Research Articles

Smelting characteristics of nickel‑chromium‑manganese bearing prereduced pellets for the preparation of nickel saving austenite stainless steel master alloys

Nickel saving austenite crude stainless steel master alloys were innovatively produced by smelting of nickel‑chromium‑manganese bearing prereduced pellets in an effective and economical way. The thermodynamics analysis and systematic process mineralogy were also conducted to further reveal the smelting characteristics of prereduced pellets and the related enhanced mechanism. The results showed that the preferable stainless steel master alloys with 66.29% Fe, 4.21% Ni, 17.28% Cr, 6.53% Mn and 4.76% C can be prepared from the nickel‑chromium‑manganese bearing prereduced pellets with a corresponding recovery of valuable metals more than 95%. Furthermore, during the enhanced smelting process, the optimization of slag types can further realize the phases transformation from high-melting-point enstatite and forsterite to low-melting-point diopside and monticellite to obtain a decreased smelting temperature and viscosity of slag. The smelting duration and the alloy grain included in the smelting slag were both obviously decreased, resulting in an improved smelting performance.

Sintering and Smelting Property Investigations of Ludwigite

In this paper, orthogonal experiments are designed to study the sintering and smelting characteristics of the ludwigite ore. The predominant influencing factors of the optimal ratio, basicity and carbon content on different single sintering indexes, including the vertical sintering speed, yield rate, drum strength and low-temperature reduction pulverization index, are firstly explored by the range analysis method, and the main influencing factors on comprehensive indexes are obtained by a weighted scoring method based on different single index investigation. Considering the sintering characteristics, the primary and secondary influencing factors are: ordinary ore ratio, carbon content and basicity, and the optimal ore blending scheme is: basicity 1.7, ordinary ore blending ratio 60% and carbon content 5%. In terms of the smelting characteristics, the research obtains the order of the influencing factors on the softening start temperature, softening end temperature, softening zone, smelting start temperature, dripping temperature, smelting-dripping zone, maximum pressure difference and gas permeability index of the ludwigite sinters by simply considering various single smelting indexes. On this basis, considering the comprehensive softening-melting-dripping characteristics, the primary and secondary influencing factors are: carbon content, ordinary ore ratio and basicity, and the optimal ore blending scheme is: basicity 1.9, ordinary ore blending ratio 60% and a carbon content of 5.5%. Comprehensively, considering the sintering and smelting property of the ludwigite ore, the primary and secondary influencing factors are: carbon content, ordinary ore ratio and basicity, and the optimal ore blending scheme is: basicity 1.9, ordinary ore blending ratio 60% and a carbon content of 5.5%.

Metallurgical Research and Its Contribution to Industrial Development

Metallurgical Research and Its Contribution to Industrial Development

Atmospheric deposition of arsenic, cadmium, copper, lead, and zinc near an operating and an abandoned lead smelter.

Atmospheric deposition samples were collected over 15 mo at several locations near an operating smelter and an abandoned Pb smelter to investigate the contribution of Pb smelting to depositional fluxes and potential local air quality degradation. Samples were analyzed for As, Cd, Cu, Pb, and Zn and subjected to scanning electron microscopy (SEM)-energy dispersive spectroscopy (EDS). Concentrations of Cd and Pb at both sites were greater than at the control site (p<.05), and significant correlations existed between Cd and Pb concentrations at both sites (p<.05). Monthly depositional flux variations at both sites were similar, with greater deposition during cold and dry periods. Heavy metal(loid)s deposition during these periods was correlated with wind speed. Greater Cd depositional flux differences were found between the smelter and control sites compared with other elements. The SEM images suggested that some particles at the operating smelter site were from Pb smelting material. However, most particles at both sites had no characteristics of smelting, suggesting reactions occurred between the smelter-emitted particles and soil components. The EDS results indicated that atmospheric deposition from both sites had lower Pb concentrations than smelting material or ash. The main atmospheric deposition source at the operating and abandoned sites was likely from the resuspension of heavy metal(loid)-enriched soil particles. Greater risk of air pollution from historical Pb smelting facilities exists years after closing down. Reducing soil wind erosional losses may help reduce heavy metal(loid)s dispersion across environments.

A RQPSO Algorithm for Multiphase Equilibrium Calculation in the KIVCET Process

The prediction of phase configurations and the optimization of operating parameters in the metallurgical process are normally achieved by the multiphase equilibrium calculation (MEC), which is formulated as a constrained optimization problem based on the principle of Gibbs free energy minimization. A revised quantum-behaved particle swarm optimization (RQPSO) algorithm has been proposed to solve the optimization problem using three-part improved strategies. Based on the KIVCET smelting characteristics, a MEC model for the KIVCET process is established and solved using the RQPSO algorithm. The calculated and industrial data of the lead grade are 96.20% and 96.33%, respectively, those of the matte grade are 19.39% and 19.68%, and the mass fractions of Pb in the predicted and industrial matte are 3.96% and 3.34%, respectively. The calculated results of the phase configuration are consistent with the actual production data, which indicates that the MEC model and RQPSO algorithm are accurate and reliable.

Assessment of Nonuniform Batch Distribution in Blast Furnace

In industry, nonuniform distribution of the material and energy resources significantly affects the stability of production processes and impairs product quality. In particular, in blast furnaces, nonuniform distribution of the batch components and the gas temperature significantly affects furnace performance. A literature review shows that the nonuniformity is usually assessed by means of various coefficients taking account of the variability in the material and energy resources in the course of production. The variation coefficient introduced by Pearson in 1895 is most commonly used. The relation between the square of the variation coefficient V2 and X2 = [n(N–1)/N]V2 is established. According to this relation, the random quantity V2 has a χ2k distribution with k degrees of freedom: k = N–1. Here n = n1 + n2 + … + nN; ni is the ith measurement (\(i = \overline {1,N} \) ); and N is the total number of measurements. The proposed method of assessing the nonuniformity is based on the statistics χ2k and X2, as proposed by Pearson in 1901 and 1904, respectively. Here X0 is intended for verification of hypothesis H0: that the empirical and statistical distributions agree. The azimuthal nonuniformity of the distribution of materials and gases in the blast furnace is based on the consistency of the Pearson statistics χ2k and X2. The quantile factor q is employed if the calculations of X2 do not employ the frequency of the measured quantities but, by analogy, the magnitudes of the physical quantities. In this method, after correction, X2 is used to assess the deviation p from a uniform distribution (the nonuniformity factor): p = p(χ2k), p ∈ (0; 1–α); χ2k= X2co-qX2. If X2 and χ2k are to be consistent for measurements of physical quantities (the temperature or pressure) or of materials (friable materials, gases), X2 must be corrected so that qX2max ≈ χ2k(α), X2max ⊂ (X21, …,X2M), where M is the number of experiments for which X2 is determined; χ2k(α) is the upper α quantile of χ2k; q is the quantile factor introduced for correction of X2; X2max is the limiting value of X2max permissible in determining the nonuniformity measure. The method is tested in estimating the relative nonuniformity of the batch components and the distribution of the azimuthal temperature for 2014- and 1370-m3 blast furnaces at OAO Magnitogorskii Metallurgicheskii Kombinat. The influence of the sequence in which the batch components are selected in the bunker of the nonconical furnace-charging system on the azimuthal nonuniformity of the materials and the smelting characteristics is analyzed.

Multiphase equilibrium modeling of oxygen bottom-blown copper smelting process

Abstract A computational thermodynamics model for the oxygen bottom-blown copper smelting process (Shuikoushan, SKS process) was established, based on the SKS smelting characteristics and theory of Gibbs free energy minimization. The calculated results of the model show that, under the given stable production condition, the contents of Cu, Fe and S in matte are 71.08%, 7.15% and 17.51%, and the contents of Fe, SiO2 and Cu in slag are 42.17%, 25.05% and 3.16%. The calculated fractional distributions of minor elements among gas, slag and matte phases are As 82.69%,11.22%, 6.09%, Sb 16.57%, 70.63%, 12.80%, Bi 68.93%, 11.30%, 19.77%, Pb 19.70%, 24.75%, 55.55% and Zn 17.94%, 64.28%, 17.79%, respectively. The calculated results of the multiphase equilibrium model agree well with the actual industrial production data, indicating that the credibility of the model is validated. Therefore, the model could be used to monitor and optimize the industrial operations of SKS process.

Copper smelting mechanism in oxygen bottom-blown furnace

The SKS furnace is a horizontal cylindrical reactor similar to a Noranda furnace, however, the oxygen enriched air is blown into the furnace from the bottom. Mechanism model of the SKS process was developed by analyzing the smelting characteristics deeply. In our model, the furnace section from top to bottom is divided into seven functional layers, i.e., gas layer, mineral decomposition transitioning layer, slag layer, slag formation transitioning layer, matte formation transitioning layer, weak oxidizing layer and strong oxidizing layer. The furnace along the length direction is divided into three functional regions, that is, reaction region, separation transitioning region and liquid phase separation and settling region. These layers or regions play different roles in the model in describing the mechanism of the smelting process. The SKS smelting is at a multiphase non-steady equilibrium state, and the oxygen and sulfur potentials change gradually in the length and cross directions. The smelting capacity of the SKS process could be raised through reasonably controlling the potential values in different layers and regions.

The effect of magnesia and alumina crucible wear on the smelting characteristics of titaniferous magnetite

The effect of magnesia and alumina crucible wear on the smelting characteristics of titaniferous magnetite

Smelting characteristics of fluxed chromite sinter and its performance assessment in electric arc furnace to produce high carbon ferrochrome

More than 80% of the high grade chromite ores are fragile and tend to form fines during their handling. In order to utilise these chromite ore fine, in ferrochrome production, agglomeration is necessary. In the present study, the direct sintering of chromite ore fines in the presence of coke breeze has been carried out, which does neither require further grinding of ore fines ( − 10 mm) nor binder. It uses suitable fluxes and coke breeze as heat source to raise temperature up to 1600°C and produces a semifused mass (20% molten phases) with good strength. The developed sinter showed very good strength properties suitable for cold handling. Since it contains higher amount of fluxes than conventional pellet, the study on its smelting characteristics is necessary to assess its suitability in Fe–Cr production. In the present paper, smelting reduction characteristics and assessment of its performance with respect to the lump ore in a 50 kVA electric arc furnace have been studied in 10 kg scale. Different smelting parameters such as coke and flux requirement, energy consumption, etc. has been optimised through both thermodynamically and experimentally to get maximum extent of reduction, metallic yield and chromium recovery. Coke (21%), quartzite (7.52%) and bauxite (10%) addition with 45 kWh of heat input was found to be optimum to achieve 76% metallic yield and 91%, chromium recovery. In the comparative study in identical condition, the chromite sinter showed much better metallic yield (76%) and higher chromium content (54.6%) in the produced ferrochrome than the lump ore (70 and 51. 9% respectively) of the same grade.

Quality assessment of foundry coke

Possible methods for quality assessment of foundry coke are evaluated with a view to predicting the smelting characteristics and the properties of the cast iron produced. This involves defining what is meant by the quality assessment of foundry coke; a literature review of existing methods of coke assessment; and the identification of possible methods for the quality assessment of foundry coke. Analysis in terms of the macrostructure, the electrical resistance, the structure of the cast iron in a cupola furnace, and the coke consumption indicates that compliance with State Standard GOST 3340-88 does not ensure satisfactory quality of foundry coke. The quality of foundry coke may be assessed in terms of the yield of volatiles, the reactivity, the mean piece size, the macroporosity, and the electrical resistance. The resistance is greatest for samples in the size class 40–60 mm and is least for the size class 60–80 mm. It increases with increase in the moisture, ash, and sulfur content. Quality assessment may be based on the content of 0.3 mm, and 0.2–0.3 mm), and also on the structural parameters of the cast iron: the shape and size of the graphite inclusions, which depend on the ash content, total sulfur content, and total moisture content in the coke. Voluntary certification may be used for the quality assessment of foundry coke.

Smelter feed quality control

Final concentrates and furnace feeds from Anglo American Platinum are routinely monitored for quality. Merensky Reef, UG-2, and Platreef concentrates are sampled at the concentrators, as well as blended feed at the smelters, and the composition and mineralogy of these samples are determined at Anglo American Research. This information allows the smelting characteristics of the concentrates to be predicted. Parameters such as the matte fall, spinel formation, and smelting energy requirement can be calculated by modelling. The concentrates are characterised by chemical analyses for base metals, precious elements and trace elements. Various QEMSCAN techniques are used to determine the mineralogy of the samples and the abundance of gangue minerals and base metal sulphides (BMS), as well as the mineral association, are reported.

Selecting the economic conditions of blast-furnace smelting by means of an information and simulation system

Using an information and simulation system, the smelting characteristics and processes in blast furnace 9 at OAO ArcelorMittal Krivoi Rog are analytically studied. The characteristics are predicted with variation in the charging parameters so as to reduce coke consumption. After confirming the coke economy at the working furnace, the new charging parameters are established for constant operation.

Effect of reductive roasting on smelting characteristics of Greek nickel laterites

Research was undertaken to determine the effect of the reductive roasting conditions on the smelting characteristics of nickel laterite ores from three different areas of Greece—Evia, Viotia and Kastoria. The roasting experiments were performed in a rotary kiln at 800°, 860° and 900°C for 10-90 min; the smelting experiments were carried out in an electric-arc furnace that allowed the melting temperature and energy consumption to be monitored. The melting temperature values of the ore and roast samples were also determined with a LECO AF 600 instrument by enploying the Seger cones technique. The Evia samples, in which the SiO2/Fetot ratio was higher than in the ores from Viotia and Kastoria, exhibited the highest melting temperatures. The lowest values were observed for the Kastoria samples owing to the presence of serpentine, which had a positive effect on their fusibility. Reductive roasting of the Evia and Viotia ore samples was beneficial for the subsequent smelting stage, but roasting of the Kastoria samples resulted in an increase in the melting temperature, possibly on account of the production of refractory oxides. Finally, in agreement with the generally accepted view that reductive roasting has a positive effect on the subsequent smelting operation, increases in the temperature and duration of roasting of a composite laterite ore sample resulted in lower energy consumption during the reductive smelting, which was attributed to fayalite formation.