Aluminate Slag Research Articles

Chemical, Mechanical, and Durability of Composites Developed from Aluminum Slag

The research investigated the chemical, mechanical and durability of composites developed from aluminum slag. Aluminum slag is a hazardous residue product of secondary Aluminum smelting. The objective of this research was to study the chemical and geotechnical properties of Al slag. To investigate the stabilization of Al slag with fly ash and GBFS binder to enhance the pozzolanic reaction. Lastly, to study the properties of developed composites and recommend the application. Aluminum slag can be categorized as black or white, with the black dross (slag) having low metal concentration and a granular-like appearance comparable to sand. White dross (slag) has a high metal concentration and contains small quantities of oxides and salts, forming huge blocks. Aluminum slag is a by-product of the foundry industry that is deposited in landfills, causing pollution such as soil, air, and groundwater contamination, as well as affecting human health. Aluminum slag recycling has become more popular in recent years, and it can now be used to make concrete and bricks instead of cement. When compared to properties obtained from composites produced from cement, Aluminum slag improves several properties of the material in this study. Properties such as compressive strength, workability, and durability of the material are found to be improved. At 40% binder and cured at 80°C, the mortar sample made from Al slag, GBFS binder, and fly ash had the highest unconfined compressive strength (UCS) of 24 MPa. The optimum number of days for curing was found to be 14 days. Based on the overall research, it can be concluded that Aluminum slag produced from the foundry industries can be stabilized with fly ash and GBFS binder to produce bricks and concrete

Optimization of high alumina slag practice in blast furnace ironmaking: an industrial approach. Part 2: Data-driven aspects

ABSTRACT The prediction of transport and thermodynamic properties of the blast furnace slag is an experimentally tedious job to accomplish as seen in part-1 of this work. Literature studies have shown that the use of machine learning in the determination of the properties as a function of composition is an effective technique for glassy slags. However, the application of machine learning and data science techniques in the prediction of high alumina slag properties has not been studied extensively so far. In this paper, the use of Support Vector Machine (SVM) and ExtraTrees Regressor have been done to predict the viscosity, liquidus temperature, and other thermodynamic properties of blast furnace type slag in the high alumina regime, i.e. Al2O3 varying from 18 to 22 wt-%. The minimization of detrimental effects of high alumina slag has been studied by varying the MgO content and CaO/SiO2 ratio in the range of 8–12 wt-% and 0.8–1.2, respectively. The accuracy of models has been tuned to be fairly high and the results of the prediction have been discussed with possible solutions to operate under the high alumina regime of blast furnace slag.

Evaluation of groundwater in aluminium slag disposal area

Aluminium slag waste is a residue from aluminium recycling activities, classified as hazardous waste so its disposal into the environment without processing can cause environmental problems, including groundwater pollution. There are 90 illegal dumping areas for aluminium slag waste spread in the Sumobito District, Jombang Regency. This study aims to evaluate the quality of shallow groundwater surrounding aluminium slag disposal in the Sumobito District for drinking water. The methods applied an integrated water quality index ( WQI) and heavy metal pollution index ( HPI), multivariate analysis (principal component analysis (PCA) and hierarchical clustering analysis (HCA)), and geospatial analysis for assessing groundwater quality. The field campaign conducted 40 groundwater samples of the dug wells for measuring the groundwater level and 30 of them were analysed for the chemical contents. The results showed that some locations exceeded the quality standards for total dissolved solids ( TDS), electrical conductivity (EC), and Al 2+. The WQI shows that 7% of dug well samples are in poor drinking water condition, 73% are in good condition, and 20% are in excellent condition. The level of heavy metal contamination based on HPI is below the standard limit, but 13.3% of the water samples are classified as high contamination. The multivariate analysis shows that anthropogenic factors and natural sources/geogenic factors contributed to shallow groundwater quality in the study area. The geospatial map shows that the distribution of poor groundwater quality is in the northern area, following the direction of groundwater flow, and is a downstream area of aluminium slag waste contaminants.

Optimization of high alumina slag practice in blast furnace ironmaking: an industrial approach (PART 1: fundamental aspects)

ABSTRACT The productivity of the blast furnace Ironmaking process is significantly dependent on the slag chemistry. The presence of compounds like Al2O3 in high quantities can make the hearth slag highly viscous and difficult to tap. The objective of part-1 of this study is to provide a comprehensive analysis of the role of high alumina (Al2O3 > 15%) compositions in the blast furnace slags. Slag viscosity, liquidus temperature, activation energy, etc., are critically reviewed with respective solutions to operate under the desired conditions. Flow parameters of the slag are examined to understand the melting-softening phenomena which directly affect the slag tap-to-tap time. The addition of certain additives to the slag system has also been studied with the aim to improve the target properties of the slag. A range of slag compositions and their optimization techniques are discussed in this part to provide greater insight into the topic.

Chloride binding and diffusion of slag blended concrete mixtures

Ground granulated blast furnace slags (GGBFS/slag) can have a range of chemical compositions, especially in alumina content that could potentially affect several concrete properties including chloride binding capacity and chloride penetration. Chloride binding capacity and diffusivity of several cement-slag combinations were assessed using two slags of 8% and 17% alumina contents and four cements, ASTM C150 Type I, ASTM C150 Type I (high alkali), ASTM C150 Type II(MH) and ASTM C595 Type IL(14) at a cement replacement level of 60%. The findings indicate slag addition improved chloride binding and lowered chloride diffusivity. Between the two slags, chloride binding capacity was higher in high alumina slag. Type I cement mixtures had the highest binding capacity while it was the lowest in Type IL cement mixtures due to lower C3A, C3S and clinker factor. Chloride diffusivity experiments showed that plain Type IL mixture had the highest chloride ion penetration while it was the lowest when blended with high alumina slag due to carboaluminate formation. Therefore, chemical, mineralogical, and physical characteristics of cement-slag combination should be considered in service life analysis of slag blended concrete mixtures.

Addition of Fly Ash and Aluminum Slag as Cement Substitute Materials to Cellular Lightweight Concrete

Most of the construction buildings that are often found use concrete as the main building material. The development of technology makes more and more new types of modified concrete, one of which is lightweight concrete. Lightweight concrete that is often found is lightweight concrete CLC (Cellular Lightweight Concrete). The construction of non-structural elements of the building applies CLC lightweight concrete at a lower cost than standard concrete due to faster work, more temperature resistance, ease of handling, and lighter density. This study aims to find the optimum percentage and effect of using aluminum slag and fly ash as a partial replacement of cement in cellular lightweight concrete. The test object is printed in a molding size of 5x5x5 cm3. The use of aluminum slag is 0%, 1.5%, 3%, 4.5%, 6%, and 7.5%, while the use of fly ash is 15% of the cement weight. The tests carried out included volume weight, compressive strength, and water absorption at the age of 3, 7, 14, 21, and 28 days. The results of this study, it can be concluded that increasing the variation of aluminum slag with fly ash content remains at 15% in each variation as a cement substitution, the most significant variation is 1.5%. The optimum compressive strength test results at a variation of 1.5% of 4.1 MPa with the highest specific gravity of 752 gr/cm3, and water absorption of 66.67%, it all specimens at the age of 28 days.

Assessment of environmental damage caused by the storage of aluminum recycling slags by enterprises with capacity up to 200 thousand aluminum alloys per year

Based on the empirical data, specific rates of ecological tax for the emission of pollutants into the atmosphere, approved by the tax code of Belarus and thermodynamic calculations the approximate specific ratio of hydrolysis products and products of their thermal oxidation, formed by exposure to humid atmosphere on the aluminum slag was determined.The work shows that the damage from atmospheric pollution by an aluminum recycling plant with a capacity of 200 thousand tons can be from 0.66 to 52.7 million U.S. dollars, that is, depending on the territorial location of the pollution source for the same substance, the damage may be increased by up to 80 times.

Processes of salt slag recycling in aluminum production to obtain powder material with a high content of aluminum oxide phases

The processing of salt slags in aluminum production in order to obtain a powder material with a high content of aluminum oxide phases and the results of thermodynamic assessment of the hydrolysis reactions of aluminum carbide and nitride during the hydraulic treatment of slags are discussed. It is reported that water‑soluble fluorine compounds, such as Na3AlF6, CaF2, MgF2, K2ZrF6 , in the composition of refining fluxes complicates the processing of aluminum slags, which involve leaching of salts by water. A rational solution seems to be the replacement of sparingly soluble salts in refining fluxes with sodium or potassium fluorides with a higher solubility in water. It is shown that the powder mixture obtained after hydraulic treatment of aluminum slag includes various forms of structural components in the form of films, shells, submicroand nanostructures of various morphologies with the participation of various types of nano‑components, in which the phases of non‑metallic compounds predominate, mainly ceramic substances and salts (corundum Al2O3, aluminum oxynitride Al2.85O3.45N0.55, aluminum nitride AlN, sodium chloride NaCl) and metallic aluminum. It is indicated that the possibility of forming eutectic mixtures of ceramic compounds of aluminum oxide and aluminum oxynitride, which are more fusible than pure oxides and nitrides, must be taken into account when developing salt slag recycling technologies in order to obtain ceramic powder materials with a high content of alumina phases.

Particle-size distribution of alumina slag after grinding

The paper considers the issues of energy consumption and effectiveness of using aluminous slag as an expansion agent compared to Portland cement. Aluminous slag is a difficult material to grind, but its use as an additive is in demand for building materials. The following research methods were used: grinding of materials, sieve analysis, electron microscopy. According to the results of studies, it was found that the use of aluminous slag as an expansion agent is effective compared to Portland cement.

Distribution ratio of sulfur between high alumina slag and carbon-saturated iron

Distribution ratio of sulfur between high alumina slag and carbon-saturated iron

Building envelope optimization using geopolymer bricks to improve the energy efficiency of residential buildings in hot arid regions

This study explored the potential of producing geopolymer bricks from industrial waste including ferrosilicon and aluminum slag. The bricks' physico-mechanical properties show that they conform to many codes and standards. Also, the thermal conductivity of 0.28 W/mK is achieved, which is significantly lower than that of conventional bricks. social residential buildings in New Aswan City, Egypt, is employed as a case study for examining the fabricated bricks' implementation. Using the Design Builder software, it was found that the proposed fabricated brick samples showed energy savings of 5.70–14.90% and a decrease in carbon dioxide emissions of 0.47–7.67% compared to conventional wall brick. The temperature profile reveals that the fabricated brick samples have achieved the desired level of human comfort. Finally, the financial viability of each brick type was analyzed using the simple payback time (SPP). A return on investment of 8.76–15.79 years was determined for the produced brick samples. Therefore, geopolymer bricks are widely recognized as a significant improvement in environmental sustainability.

Early age hydration of model slag cement: Interaction among C3S, gypsum and slag with different Al2O3 contents

A deeper insight into SO3/Al2O3 ratio including the contribution of alumina in slag at early age is required to ensure a properly sulfated slag cement. In this paper, to investigate the effect of gypsum and alumina of slag, emphasis was laid on the hydration characteristics of C3S-gypsum-slag system during the early age, of which slag was synthesized in the laboratory with varying Al2O3 contents from 3.69 to 18.19 wt%.The duration of dormant period during the hydration of C3S depended on Al2O3 content of slag significantly; however, the amount of silicate reaction before the onset of aluminate reaction was independent of slag chemistry and gypsum content added. The rate of aluminate reaction was controlled by the availability of reactants, SO42− and Al3+ ions in particular, which were sourced from gypsum and slag, respectively. Calcium monosulfoaluminate only occurred in mixture when slag contained a high amount of Al2O3 (18.19 wt% in this study) at early age, and its formation proceeded continuously at the expense of ettringite. Sulfur rich species incorporated in slag started to participate into aluminate reaction after the main hydration peak of C3S, and it played a similar role to gypsum.

Preparation and 3D printing building application of sulfoaluminate cementitious material using industrial solid waste

The iron and steel industry , the power industry, and the mining industry each produce large volumes of industrial solid waste. These industrial solid waste are dumped in huge volumes over a wide geographical distribution , causing far-reaching environmental harm in China. To date, the preparation of eco-friendly construction materials from industrial solid waste is one of the feasible large-scale utilization methods. This paper studied the preparation of different types of environmentally benign novel green sulfoaluminate cementitious materials with different contents of Ca 4 Al 6 SO 16 and Ca 2 SiO 4 by using stone tailing, coal gangue , secondary aluminum slag, and desulfurization gypsum . Moreover, the prepared solid-waste-based sulfoaluminate cementitious material (SCM) was used to further prepare 3D printing material. The results show that the optimal calcination conditions are 1260–1290 °C for about 1 h, and the main mineral phases in the clinker system are Ca 4 Al 6 SO 16 , Ca 2 SiO 4 , and Ca 4 Al 2 Fe 2 O 10 . The compressive strengths of hydrated specimens reached 40, 61, and 86 MPa after curing for 1d, 3d, 28 d, respectively, and the main mineral phases of the hydration product were ettringite , alumina gel, and silica gel . After improving its properties by using a suitable accelerant and retardant , the SCM showed advantages of a controlled setting time in the range of 15–80 min, rapid hardening, and rapid attainment of mechanical strength. The compressive strength of hydrated specimens reached 15–20 MPa after curing for 2 h, and the modified SCM proved to be eminently suitable for 3D printing applications. These results provided not only a sustainable mode for 3D printing construction materials and development, but also an innovative strategy for full utilization of industrial solid waste. • A new synthetic method to prepare eco-friendly 3D printing building materials is described. • The novel technological process of SCM from hazardous and industrial solid wastes was proposed. • Effect of raw mix composition and sintering temperature on properties of SCM was analyzed.

Effects of alumina slag (Valoxy) and rice husk ash as substitute resources on mechanical properties of mullite based ceramics

In this study, mullite-based ceramics were prepared by substituting alumina slag (valoxy) and rice husk ash (RHA) for commercially pure alumina and quartz, respectively. Five body compositions containing 5, 10, 15, and 20% valoxy: RHA were created. At 75MPa load, the formulated bodies were thoroughly mixed homogeneously and uniaxially compacted to produce cylindrical shaped samples 30 mm diameter and 50 mm high. After compacting the samples, they were sintered in a muffle furnace at 1200 ℃ at a rate of 10 ℃/min for 2 hours before being allowed to cool to room temperature before offloading. Mechanical properties such as microhardness and compressive strength was conducted on the samples to determine the effects the substitute materials have over the formulated mullite ceramics. The results showed maximum hardness (16 GPa) and compressive strength (56.76 GPa) was observed for samples containing 2.5 % valoxy: 2.5 % RHA respectively while decline in hardness and compressive strength was observed for the remaining compositions. Thus, indicating that the use of these wastes materials is only beneficial at lower percent inclusion.

Effects of alumina slag (Valoxy) and rice husk ash as substitute resources on mechanical properties of mullite based ceramics

Effects of alumina slag (Valoxy) and rice husk ash as substitute resources on mechanical properties of mullite based ceramics

Investigating Aluminum Tri-Hydroxide Production from Sodium Aluminate Solutions in the Pedersen Process

This study investigates applying the principles of the long-discontinued Pedersen process as a possible route for producing metallurgical grade alumina from low-grade and secondary feed materials. The investigation focused on the hydrometallurgical steps in the process, namely leaching, desilication, and precipitation, and adapting it to valorize bauxite residue. The test material used was a calcium–aluminate slag made by the smelting-reduction of a mixture of bauxite residue (dewatered red mud) and a calcium-rich bauxite beneficiation by-product. Samples of the slag were leached in a 1 L jacketed glass reactor with Na2CO3 solution, varying Na2CO3 concentration and leaching time. Additionally, different approaches to leaching involving mechanical treatment of the leached slag and re-leaching using either fresh or recycled solution were also explored. The desilication step was carried out by treating the leachate solution with powdered CaO, varying the amounts of CaO used. Finally, the desilicated leach solution was sparged with a CO2 gas mixture, after which the precipitate was allowed to age in the solution. The carbonation and aging temperatures and times were varied. As much as 67% of the Al was leached from the slag. The desilication process successfully removed 88% of the Si. The precipitation process produced a product composed mostly of bayerite [Al(OH)3], but some tests had considerable amounts of the unwanted phase dawsonite [NaAlCO3(OH)2]. The results indicated that the highest Al recovery was obtained using low concentrations of Na2CO3 solutions, and aluminum tri hydroxide is formed from these solutions at low temperatures at a fast rate compared to higher solution concentrations and temperatures.

JARINGAN PENGANGKUT TANAMAN PEPAYA (Carica papaya L.) YANG TUMBUH PADA TANAH TINGGI ALUMUNIUM

Purpose of this study is to determine the anatomical differences of transport tissue (xylem and phloem) in Carica papaya L. Roots, which grown on contaminated and uncontaminated Al (Aluminum). The study was carried out by digging 0-30 cm of soil to take 3 lateral roots, then cut transversely, stained using xylol and observed the transport tissue using a computer binocular microscope with a magnification of 100x. Based on the research, it is known that the xylem and phloem of transport tissue obtained from the roots of Carica papaya L. which grows on soil contaminated with aluminum slag ash has differences with the root transport tissue of Carica papaya L. which grows on soil without aluminum slag ash contamination.

Thermal study of the hydrocalumite–katoite–calcite system

Hydrocalumite (Ca2Al(OH)6Cl·2H2O) samples were prepared by the coprecipitation method, using Al3+ obtained from an aluminum slag, extracted in NaOH solutions and purified removing silica by precipitation with HCl. Hydrocalumite aging was assisted by microwave irradiation, and carried out under different temperatures. Very pure hydrocalumite was obtained under certain conditions, but samples impurified with katoite (Ca3Al2(OH)12) and calcite (CaCO3) were obtained in other cases. The thermal decomposition of hydrocalumite is complex and is not completely elucidated, compounds such as Ca12Al14O33 (mayenite), Ca(OH)Cl and CaO have been proposed. The thermal characterization of this system was studied, also considering samples impurified with katoite and calcite, as a valuable and rapid method for identifying these phases.

Effects of BaO Content and CaO/Al2O3 Ratio on the Properties and Structure of Aluminate Slag

Effects of BaO Content and CaO/Al2O3 Ratio on the Properties and Structure of Aluminate Slag

Effect of Synthesis Conditions on Mechanical Strength of Aluminium Slag Modified Waste Foundry Sand Geopolymers

The waste foundry sand was alkaline activated into geopolymers to reduce their environmental pollution. The waste foundry sand was blended with aluminium slag and alkali activated to produce geopolymers. Aluminium slag was used to supplement WFS with alumina because as it has low content of alumina. The main parameters tested were the effect alumina content, concentration of alkali, liquid to solid ratio, and temperature. The optimum synthesis parameters were a geopolymer prepared with 2% aluminium, 3 M NaOH solution, liquid solid ratio of 0.15 and curing temperature and time of 80°C and 5 days respectively. The optimum parameters yielded the highest UCS of 4.7 MPa. The developed aluminium slag modified waste foundry sand geopolymers met the minimum requirements for ASTM C126-99 and ASTM C216-07a.