Aluminate Slag Research Articles

Thermodynamic study on the formation of Mg(Al1-x,Fex)2O4 between single-crystal MgAl2O4 and FetO-containing slag at 1550°C

Herein, the effects of FetO content and basicity (CaO/Al2O3) on MgO solubility in calcium aluminate slag were evaluated. The experimental results revealed that the dependence of MgO solubility on basicity reversed across the equilibrium region as the phase changed from MgO to spinel. Meanwhile, a dense layer of Mg(Al1-x,Fex)2O4 solid solution formed at the interface between the single-crystal MgAl2O4 and FetO-containing MgO-saturated slag. Thermodynamic evaluation of the spinel solid solution formation indicated that the solid solubility of ferric ions (Fe3+) in the reaction layer was dominated by the redox equilibria of ferrous (Fe2+) and ferric ions in the slag. The standard Gibbs free energy change (ΔG°) of the formation of Mg(Al1-x,Fex)2O4 solid solution was derived considering both the energy change in mixing (ΔG°Mix) from the configurational change and the cation distribution owing to the inversion in the spinel, as well as a chemical reaction (ΔG°Rxn) with the FetO-containing slag. The dissolution mechanism via the substitution of cations, as inferred from these calculations, is discussed in detail.

FactSage Studies to Identify the Optimum Slag Regime for Blast Furnace Operation

Decreasing the slag rate can lead to a lower fuel rate and higher productivity in the blast furnace (BF). Indian iron ore is known to have adverse alumina–silica ratio. Therefore, to reduce the slag rate there is a need to either remove alumina from the iron ore or to add more silica to dilute the effect of alumina in slag. The latter would increase the slag rate, while the other option is not cost effective. The slag rate can be reduced by operating the BF at high Al2O3%. However, high Al2O3% in BF slag has an adverse impact on liquidus temperature and viscosity. Therefore, there is a prerequisite to identify a slag regime that has low liquidus temperature and low viscosity. In the present work, the FactSage studies of 275 no. of BF slags at wide chemistry variation (Al2O3 = 17–25%, MgO = 8–16%, slag basicity = 0.96–1.2) are conducted to calculate the liquidus temperature and viscosity of slag. Based on the FactSage calculation, it has been identified that 12% MgO coupled with slag basicity ~ 1.0 is the most favorable composition for 22% Al2O3 in slag operation to achieve a lower liquidus temperature and lower viscosity which is essential for efficient BF operation.

Experimental and mechanism research on carbothermal reduction of spodumene ore via vacuum

Considering the low resource utilisation rate and high environmental pollution afflicting the current technology for extracting Li from spodumene ore, this report proposes a clean process for the vacuum carbothermal reduction of spodumene ores for Li extraction, ferrosilicon alloy preparation, and alumina recovery. Thermodynamic analysis indicated that vacuum conditions can significantly promote the carbothermic reduction of spodumene ores and that the initial reaction temperature can be reduced by 480 K when an environmental pressure of 20 Pa is applied. According to the experimental results, two important factors in the above procedure are the reduction temperature and reduction time. When the reduction temperature was 1648 K and the reduction time 3 h, the reduction rate of Li in the spodumene ore exceeded 90%. Furthermore, the ferrosilicon alloy and alumina slag could be effectively separated from the reduction residue. The thermodynamic equilibrium simulation of the reduction process was combined with the experimental results to assess the vacuum carbothermal reduction mechanism of spodumene ores. Compared with the existing Li extraction approach, this method has the advantages of a straightforward process flow, almost zero waste water/waste residue production, environmental compatibility, and increased resource exploitation. Based on the above, this work provides new insights for advancing the conventional technology used for Li extraction from spodumene ores.

Slag Chemistry and Behavior of Nickel and Tin in Black Copper Smelting with Alumina and Magnesia-Containing Slags

The global amount of waste electrical and electronic equipment (WEEE) is growing fast. Non-ferrous metals represent a large portion of this waste, and they can be potentially recovered via black copper smelting. Alumina and magnesia, originating from the e-waste or fluxes, can be present in the feed of a secondary copper smelter in varying concentrations. Our study focuses on the impact of MgO on the slag chemistry of high-alumina iron silicate slags. The distributions of tin and nickel as minor elements were also investigated and compared with literature data. The equilibrium study was performed at 1300 °C in reducing conditions. Three different slag mixtures with 0, 3, and 6 wt% MgO were used in the study. The MgO addition significantly reduced the solubility of alumina in the slag and changed the primary spinel phase composition. The combined effects of increasing MgO and decreasing Al2O3 concentration in the slag regarding the distribution of tin were noticeable, i.e., its deportment to metal phase increased, but for nickel the effect was negligible. Theoretical calculations were performed for estimating the isolated effect of MgO on the distributions and they confirmed the beneficial effect on the behavior of tin but showed no impact for nickel.Graphical

POTENSI PEMANFAATAN SLAG ALUMINIUM SEBAGAI SUBSTITUSI SEMEN DALAM PROSES STABILISASI/SOLIDIFIKASI LIMBAH B3 DENGAN KAJIAN PUSTAKA (STUDI KASUS : PT.X KECAMATAN KESAMBEN, JOMBANG)

Slag aluminium tergolong limbah bahan berbahaya beracun (B3) dalam PP 101 tahun 2014 dengan kode B313-2 dan efeknya kronis. Penelitian ini bertujuan untuk mengetahui potensi pemanfaatan slag aluminum dengan menganalisa karakteristik limbah, proses solidfikasi dan kualitas kuat tekan dan TCLP produk solidifikasi. Hasil penelitian menunjukkan karakteristik slag memiliki kandungan unsur B3 sesuai PP 101 tahun 2014 wajib dikelola, salah satunya dengan Stabilisasi/solidifikasi. Metode analisa pemanfaatan solidifikasi limbah slag aluminium dalam penelitian dilakukan dengan pengahancuran (crushing), penggilingan (grinding), pemilahan (sorting) dari aluminium dross dan pemulihan metal dengan peleburan. Slag berpotensi dimanfaatkan sebagai bahan konstruksi seperti beton geompolimer, bata beton, batako, dan paving block. Komposisi slag aluminium dengan solidifikasi menunjukkan tidak melebihi 20% karena produk akan mengalami perlindian. Uji Kuat Tekan slag tertinggi pada PT.X jombang sebagai paving block tertinggi yaitu 36,8 Mpa yang dapat dimanfaatkan sebagai lahan parkir. Uji TCLP dari pemanfaatan slag aluminium memenuhi standar USEPA dan aman bagi lingkungan.
 Kata Kunci : slag aluminium, solidifikasi, kuat tekan, TCLP

Valorization of Al slag in the production of green ceramic tiles: Effect of experimental conditions on microstructure and crystalline phase composition

AbstractThis work reports the results of an investigation aimed at the development of sintered glass‐ceramic tiles by the sinter‐crystallization of mixtures composed of aluminum slag and reclaimed packaging glass. The thermal behaviors of mixtures incorporating 50 and 60 wt% Al slag were established by differential thermal analysis (DTA). Green compacts were sintered in a temperature range of 800°C‐1050°C and then soaked for 10‐60 minutes. The mineralogical characterizations of the sintered materials were obtained by X‐ray diffraction (XRD). The achieved results indicated that the sintering of aluminum slag and packaging glass reclaimed led to a glass‐ceramic material composed mainly of needle‐like crystals of wollastonite (CaSiO3). The bloating of samples during firing was evaluated according to a Cougny predictive diagram. After initial observations and according to bending strength characterizations, sintered tiles prepared from aluminum slag and glassy sand are appropriate for floor pavement and wall covering.

Leaching kinetics and mechanism of slag produced from smelting-reduction of bauxite for alumina recovery

In the present study, we investigate the kinetics and mechanism of the leaching of calcium aluminate slag in Na2CO3 solution for alumina recovery. The slag consists of leachable phases, e.g., 12CaO·7Al2O3, CaO·Al2O3, 5CaO·3Al2O3, and a non-leachable phase that contains Ca-Al-Si-Ti oxides. A series of leaching treatment is done at different temperatures, leaching times, stirring rates, Na2CO3 concentrations, and different setups which includes wet-grinding and shaking-digestion reactor. The highest alumina recovery up to 90.5% is obtained after the slag is leached by 10 wt% Na2CO3 solution, at low temperatures (30–45 °C) within 90 min. It is shown that the rate of alumina recovery is high at the beginning of leaching and is then slow down due to the calcite layer product nucleation and growth at the surface of slag. The wet-grinding leaching and vigorous stirring increase the possibility of the collision between both particles and the stirrer that breaks the calcite layer, yielding less residue agglomeration and better recovery compared to the slow and mild agitations. A surface observation of the slag using electron microscopy shows that the calcite starts to nucleate at the non-leachable phase as the best deposition site, which has the least mass transfer barrier in the system. The apparent activation energy of the leaching reaction is calculated as 10.8–19.9 kJ/mol, which indicates the reaction is diffusion rate-limited as revealed by the applied kinetic models.

Effects of SiO2 and B2O3 on MgO solubility and ionic structure in MgO-and-spinel doubly saturated aluminate slag

The effects of SiO2 and B2O3 on the ionic structure of CaO–Al2O3 binary slag under the MgO-and-spinel doubly saturated (MSDS) condition were evaluated by measuring the MgO solubility of the slag. The activity coefficient of AlO45− in the slag was deduced by evaluating the equilibrium constant of the ionic reaction. In addition, the proportion of each bridging oxygen (BO) linkage species and the enthalpy of solution with the 4-coordinate Al ion (4Al) were derived by combining the Al avoidance model with the 11B and 27Al magic angle spinning nuclear magnetic resonance spectra results. The enthalpies, activity coefficient of AlO45−, and enthalpy of the solution with 4Al had good agreement in BO-dominant regions. From these results, the effects of the structural properties of slag on the stability of AlO45− and MgO solubility in the MgO-and-spinel doubly saturated slag were investigated in detail.

Ecological Assessment of the Cucumber Plants Reaction to the Use of Production Waste and Natural Minerals in the Composition of Nutrient Soils

The article discusses one of the waste management areas – the use of fertilizer properties of chemical compounds that make up various types of production waste. The salt aluminum slag of the Mtsensk metallurgical plant AOOT Non-ferrous Metals and Alloys was chosen as the object of pollution. The presented studies indicate that the presence of macro-and microelements in the composition of slag fertilizers significantly increases the value of these fertilizers and partially solves the problem of complex application of the necessary elements into the soil [10]. The effectiveness was evaluated of the fertilizing properties of the salt screenings of aluminum slag, vermicompost and zeolites when using them as a part of nutrient soils for growing cucumber [8]. An increase in the toxic load for the analyzed period was established [7]. Also, all the studied forms and types of fertilizer nutritional compounds have a physiological effect, increase the growth and development of cucumber plants, product quality, and contribute to plant resistance to adverse environmental conditions and to the production of environmentally friendly products [13]. The effectiveness has been proved of the method of using plant cell juice electrical conductivity to assess the physiological state at different growth phases as a reaction to the fertilizer levels of production waste and natural minerals [9].

Production of Ferrosilicoaluminium from Aluminum Slag and Local Ore Via Carbothermic Reduction

This paper deals with the possibility of obtaining FeSiAl complex alloy by carbothermic reduction in a submerged arc furnace using aluminum dross, mill scale and feldspar.Bench scale experiments are carried out to clarify the effect of different variants such as reducing agent, basicity, and mill scale content of the charge on the metallic yield and chemical composition of the produced alloy.It was possible to get FeSiAl alloy containing 22% Si and 18% Al. the results reveal that to obtain such alloy less than 20% mill scale must be involved in the charge and the coke with amount 1 stoichiometric must be used.

Composite Binders for Fastening High Temperature Wells

The article deals with the hydration of oil-well cement, intended for cementing high-temperature wells. At high temperatures and pressures (150°C, P = 30 MPa) Portland cement stone does not have the necessary density and resistance to high temperatures due to the formation of hydrated calcium silicates rich in lime during the hydration of Portland cement, therefore, the work was carried out primarily to find appropriate additives to Portland cement, providing the necessary properties of oil-well cement. From a number of additives to ensure the durability of service were selected reprocessing waste of titanium ores (titanomagnetite concentrate) and blast furnace slag. In addition, to improve the crack resistance of cement stone, the possibility of using expansive additives to oil-well cement was investigated. For these purposes, sulfoaluminate, sulfoferrite clinkers and alumina slag were used.It has been established that during hydration of calcium sulfoferrite ferrous ettringite is formed, which is more stable at elevated temperatures than ettringite formed at hydration of sulfoaluminate clinker and alumina slag. In the presence of sulfated phases and silica, at elevated temperatures and pressures, low-base calcium silicates hydrates and iron contained garnet hydrates are formed.

Recycle of vanadium from aluminum slag of ferrovanadium

Vanadium is a rare chemical element and it primarily comes from the by-product of other minerals. In this study, the material source mainly comes from vanadium-rich aluminum slag. This experiment aims to separate vanadium and other impurities, such as aluminum and zirconium. First, the slag was dissolved in the sodium hydroxide solution at pH value 13, and part of the alumina was precipitated. After removing the precipitation, the strong acid cation exchange resin, Dowex® G26, was added to eliminate the remaining impurities. In this procedure, the parameter of reaction time, the mass of ion exchange resin and pH value were supplied. Moreover, the adsorption isotherms described by means of the Langmuir and Freundlich isotherms were used to investigate the ion-exchange behaviors of vanadium. To sum up, this study will provide the best conditions of ion exchange to get high purity about 95% of vanadate.

Analysis of aluminum scrap processing technology

The analysis of aluminum scrap processing technologies is presented taking into account the economic and environmental components. Acid-alkaline methods sulfate and soda methods, as well as electric arc remelting of aluminum slag in a single-phase AC electric arc furnace are considered. A significant number of problems are noted regarding the mechanical and electro physical characteristics of manufactured products. The solution of these issues, taking into account the increasing requirements of the consumer, is possible only when performing special studies in terms of improving technology and developing devices and devices for new technological processes

Reaction Behavior of Coke in a High Alumina Slag

The reaction behaviors between coke and CaO–SiO–MgO–AlO–CrO slag at different immersion time, temperature and rotation speeds were studied in this work. The diameter decrement of the coke increased as increasing the immersion time, temperature and rotation speed. When the coke was in contact with the molten slag, the slag could infiltrate into the coke and further flow to the interior of the coke through pore channels, which will fill up the coke pores. During the penetration process of slag into the coke, the carbon could be oxidized by CrO and SiO in the slag. Furthermore, the penetrated slag could also dissolve the coke ash minerals and react with that to form new phase. The comprehensive effects of slag penetration, slag-carbon reaction and slag-mineral reaction eventually resulted in the coke degradation.

Utilization of Industrial Waste Products in the Production of Asphalt Concrete for Road Construction

Abstract The utilization of industrial waste products to produce asphalt concrete for road construction was investigated. Aggregates were partially replaced with aluminum slag (AS) and crushed ceramic tiles (CCT) at 10%, 20%, 30%, 40%, and 50% by weight. Physical tests were performed on the aggregates, while a flash and fire point test as well as penetration tests were carried out on the bitumen. Similarly, Marshall stability tests were conducted on cylindrical specimens of the asphalt concrete. The average values of 18.88 and 30.69 obtained for the aggregate impact value (AIV) and aggregate crushing value (ACV) were satisfactory for road surfacing when compared with the specification. Marshall stability values of 10.84 KN, 4.27 KN, and 3.21 KN respectively were obtained with 30%, 20%, and 50% partial replacements with AS. The percentages were suitable for heavy, medium and light traffic when compared with the Marshall design criteria provided by the Asphalt Institute. The use of aluminum slag and crushed ceramic tile could reduce the large volume of industrial waste and the cost of pavement construction and maintenance.

Desulfurization Model Using Solid CaO in Molten Ni-Base Superalloys Containing Al

Details of the desulfurization for molten Ni-base superalloys containing Al using solid CaO have been investigated, and the formula that explains the reaction rate has been developed. A cylindrical CaO rod was inserted into 500 g molten Ni-base superalloy TMS-1700 (MGA1700) containing 200 ppm S and held for a certain period at 1600 °C in each experiment. Sulfur content in the melt decreased with the increasing holding time of the CaO rod. Results of electron probe microanalysis show that Ca, O, S, and Al distribute in the same part of the melt/CaO interface as well as the particle boundaries of the CaO rods. The distribution of these elements suggests that CaO reacted with S in the melt to generate CaS, and Al reacted with O and CaO to form calcium aluminate slag. The desulfurization rate formula was obtained by the assumption that the rate-controlling process of the desulfurization is S diffusion through the generated layer composed of CaS and calcium aluminate slag. This formula expresses the amount of S in the melt by the diffusion term with the effective diffusion coefficient, which was obtained from the experimental results. Moreover, the time required for the desulfurization of 2 kg molten Ni-base superalloy PWA1484 using a CaO crucible, was calculated by this desulfurization rate formula which resulted in fair agreement with the actual result.

Engineering Properties of Concrete by Partial Replacement of Cement with Aluminium Slag and Fine Aggregate with Foundary Sand

A self-compacting concrete (s.c.c) is a special concrete which settles itself without any vibration due to its own mass and self-weight. This will happen due to use of special admixtures which have tendency to increase the flow of concrete by reducing the viscosity nature. This particular type of concrete was developed by the japan researchers in 1988. Later it was modifies and developed in many parameter’s by UK and U.S.A researchers. This particular thesis is about the improvement of performance of the S.C.C by replacing the fines and cement of the aggregates by the waste products that obtained from the different industries. The fines are replaced partially by crushed sand obtained as quarry waste and the aluminium slag that obtained from many industries as a waste product is partially introduced as binding material By using this S.C.C the problems that are facing by the construction industries during the placement of the concrete will solve. Now days the structures are designed and made as heavy reinforced structures where the sizes of structural elements are restricted due to architectural and some structural considerations. So the concrete that poured in those elements shows the voids and honey combing it can be prevented by using this S.C.C. not only the improvement of the strength but also the construction time and cost also gets reduced by using this product, because with this material no need of vibration. It reduces the time of construction and cost regarding vibration equipment and labor. But the main problem while preparing s.c.c is to select the proper admixture to prevent the cracking and shrinkage issues. This type of concrete requires 20-25 percent higher matric paste when compared to conventional concrete. This thesis works on mainly preparing the most feasible mix for s.c.c with the partial replacement of fines and cement by above mentioned materials which makes the matrix still in plastic state without altering the original properties of the concrete. The second task is to prepare the specimens for different strength tests and like compression and tensile and bending parameters check along with the considering the shrinkage issues.

Influence of Na2CO3 and CaCO3 additions on the aluminate slag formation during a single-stage reducing roasting of red mud

Influence of Na2CO3 and CaCO3 additions on the aluminate slag formation during a single-stage reducing roasting of red mud

Semi-Smelting Reduction and Magnetic Separation for the Recovery of Iron and Alumina Slag from Iron Rich Bauxite

This work presents a semi-smelting reduction and magnetic separation process for the recovery of iron and alumina slag from iron rich bauxite ore. The effect of the process parameters on the recovery rate of iron, maximum particle size of the iron nugget, and the Al2O3 content of the alumina slag was investigated and optimized. The results show that the iron nuggets and alumina slag can be obtained in a short time through a semi-smelting reduction and magnetic separation process. The maximum particle size of iron nugget is about 15 mm, and the recovery rate of the iron and Al2O3 grade of the alumina slag are 96.84 wt % and 43.98 wt %, respectively. The alumina slag consisted mainly of alumina (α-Al2O3), calcium hexaluminate (CaAl12O19), gehlenite (Ca2Al2SiO7), and small amounts of hercynite (FeAl4O7), and metallic iron (M.Fe).

Polychlorinated naphthalene emissions to the atmosphere from typical secondary aluminum smelting plants in southwestern China: concentrations, characterization, and risk evaluation.

Secondary aluminum smelting industry, as an important source of polychlorinated naphthalene (PCN) in environment, has been concerned in recent years. To figure out the emission characteristics of PCNs and the potential influence on surrounding environment, two typical secondary aluminum smelting plants were selected and PCNs were determined in flue gas, fly ash, aluminum slag, soil, and air samples collected at and around the plants by GC-MS coupled with DFS. PCN emission factors from the flue gas of the two plants (mean 0.006ng toxic equivalents/t) were found obviously decreased compared with similar smelting process detected in 2010. The stage of feeding material was still the major PCNs discharge period during the whole smelting process. The total PCN concentrations in air were found to be ranked as following: workshops (290-1917pg/m3), the area near the workshops (62.3-697pg/m3), and the surrounding areas (29.9-164pg/m3, mean 64.5pg/m3). Similar high concentrations of PCNs were found in soil from by the workshop door (983ng/g dry weight). Soil-air exchange calculations indicated that mono-CN to tetra-CN would volatilize but hepta-CN and octa-CN would be deposited to the soil. Exposure of plant workers and local inhabitants to PCNs through inhalation was found to be acceptable but higher (especially for workers in the workshops) than living areas. The workshop and the nearby area are potential PCNs polluted areas and should be paid attention during the practical operation.