Search Results (6)

The production of iron castings in cupola furnaces is a significant industrial process that has a notable impact on the environment. This paper examines and describes the environmental impact of this process, specifically focusing on the generation, characterization, and utilization of waste materials through data analysis and collection. Approximately one hundred and two million metric tons of castings are produced worldwide each year, with approximately one ton of foundry waste generated for every ton of castings. The slag from this waste can amount to as much as 7.14 million metric tons annually. Most of the slag ends up in landfills, which is expensive and represents a waste of this potential secondary raw material. Therefore, it is necessary to find ways to utilize this waste in other processes or industrial sectors. Cupola slag, given its high phosphorus content, can be used as agricultural fertilizer or in the production of ceramic foam used in foundries as filters during casting. In the construction industry, slag can be used in the production of concrete as a partial substitute for fine aggregate. This concept not only mitigates the environmental impact of waste disposal, but also aligns with the circular economy concept, promoting resource efficiency. Full article

The aim of this research was to determine the factors affecting the metallurgical quality of cast iron during serial production of castings using a campaign cupola and a holding furnace. The problem to be solved, which was to obtain cast iron with the required mechanical properties while reducing the internal porosity, results from the foundry’s need to increase the metallurgical quality of the alloy. The increasing difficulty and complicated constructions of castings, for which it is not possible to introduce risers at the stage of technological design, make the stage of proper preparation of cast iron the only way to obtain castings without shrinkage defects. The article presents the results of the study of physicochemical and mechanical properties, microstructure and shrinkage tendency of ductile iron depending on the charge materials used, the amount of Mg used during spheroidization and the type of final inoculants. Step castings and wedge tests were produced on a vertical molding line. The spheroidization was carried out by injecting a core wire containing Mg alloy into the cast iron. The final inoculation of 0.2% was performed using a pneumatic dispenser equipped with a vision system to control the effectiveness of the inoculation. The ITACA Meltdeck thermal analysis system was used to study the physicochemical properties of the initial cast iron, and the ITACA X system to analyze the state of the final cast iron on the molding line. Mechanical tests were performed on samples cut from a stepped casting, and microstructure tests were carried out using a light microscope and a scanning electron microscope. The results of thermal analyses show that increasing the share of pig iron at the expense of steel increases the minimum solidification temperature of eutectic, and thus, increases the potential for graphite nucleation in cast iron. Increasing the nucleation potential can be obtained by adding anthracite, FeSi and SiC. A very important factor in obtaining cast iron of high metallurgical quality is the possible limitation during spheroidization of the length of the core wire containing Mg, which is a carbide-forming element. The lower the initial sulfur level, the greater the possibility of reducing the amount of cored wire. The inoculants containing Ce and Bi were the most advantageous final inoculants from the point of view of obtaining the best microstructure parameters and plastic properties of cast iron. Full article

The development of self-compacting concretes with electric arc furnace slags is a novelty in the field of materials and the production of high-performance concretes with these characteristics is a further achievement. To obtain these high-strength, low-permeability concretes, steel slag aggregates and cupola slag powder are used. To prove the effectiveness of these concretes, they are compared with control concretes that use diabase aggregates, fly ash, and limestone supplementary cementitious materials (SCMs, also called fillers) and intermediate mix proportions. The high density SCMs give the fresh concrete self-compacting thixotropy using high-density aggregates with no segregation. Moreover, the temporal evolution of the mechanical properties of mortars and concretes shows pozzolanic reactions for the cupola slag. The fulfillment of the demands in terms of stability, flowability, and mechanical properties required for this type of concrete, and the savings of natural resources derived from the valorization of waste, make these sustainable concretes a viable option for countless applications in civil engineering. Full article

The foundry industry is currently facing challenges to reduce the environmental impacts from application of fossil fuels. Replacing foundry coke with alternative renewable carbon sources can lead to significant decrease in fossil fuel consumption and fossil CO₂ emission. The low bulk density, low energy density, low mechanical strength and the high reactivity of biocarbon materials are the main factors limiting their efficient implementation in a cupola furnace. The current study aimed at designing, optimizing and developing briquettes containing biocarbon, namely, biocarbon briquettes for an efficient use in cupola furnace. Laboratory hydraulic press with compaction pressure of about 160 MPa and stainless-steel moulds (Ø = 40 mm and 70 mm) were used for compaction. The density, heating value, energy density, mechanical strength and reactivity of biocarbon briquettes were measured and evaluated. The compressive strength and splitting tensile strength of biocarbon briquettes were measured by a compression device. The reactivity of biocarbon briquettes was measured under controlled conditions of temperature and gas atmosphere using the thermogravimetric analysis technique (TGA). Different types of binders were tested for the compaction of commercial charcoal fines with/without contribution of coke breeze. The effect of charcoal ratio, particle size, binder type, binder ratio, moisture content and compaction pressure on the quality of the biocarbon briquettes was investigated. Molasses with hydrated lime and cement were superior in enhancing the biocarbon briquettes strength and energy density among other tested binders and additives. The briquettes’ strength decreased as the biocarbon content increased. The optimum recipes consisted of 62% charcoal fines, 20% molasses, 10% hydrated lime and 8% cement. Cement is necessary to develop the tensile strength and hot mechanical strength of the briquettes. The charcoal with high ash content showed higher strength of briquettes but lower heating value compared to that with low ash content. Dispersion of silica suspension on charcoal particles during the mixing process was able to reduce the reactivity of biochar in the developed biocarbon briquettes. The biocarbon briquettes density and strength were increased by increasing the compaction pressure. Commercial powder hydrated lime was more effective in enhancing the briquettes’ strength compared to slaked burnt lime. Upscaling of biocarbon briquettes (Ø = 70 mm) and testing of hot mechanical strength under load indicated development of cracks which significantly reduced the strength of briquettes. Further development of biocarbon briquettes is needed to fulfil the requirements of a cupola furnace. Full article

A number of carbon-rich (containing up to 47 wt% C) and lime-rich (containing up to 96 wt% of CaO-compounds) waste products from the pulp and paper industries can be used in iron and steel industry as fuels and slag formers for various metallurgical processes such as blast furnaces (BF), cupola furnaces (CF), argon oxygen decarburization (AOD) converters and electric arc furnaces (EAF). In most cases, these wastes consist of different size powders. In order to facilitate loading, transportation and charging of these powder wastes, briquetting is required. In this study, a pulverized AOD slag was tested as a binder component for briquetting of CaO-containing wastes (such as mesa, lime mud and fly ash) from pulp and paper industries. Moreover, mechanical testing of the possibilities for loading, transportation and unloading operations were done, specifically drop test trials were done for briquettes with different chemical compositions and treatments such as heating and storage. The results showed that an addition of 10–20% of AOD slag as a binder component followed by heat-treatment at 850 °C significantly improved the mechanical properties of the CaO-containing briquettes. An application of these briquettes will significantly reduce the consumption of natural resources (such as nature lime) in the metallurgical processes. Moreover, it can reduce the landfill area of wastes from pulp and paper industries, which is important from an environmental point-of-view. Full article

Between 2004 and 2011 the German Government funded 17 different projects to develop techniques of phosphorus recycling from wastewater, sewage sludges, and sewage sludge ashes. Several procedures had been tested, such as precipitation, adsorption, crystallization, nano-filtration, electro-dialysis, wet oxidation, pyrolysis, ion exchange, or bioleaching. From these techniques, 32 recycling products were tested by five different institutes for their agronomic efficiency, that is, their plant availability, mainly in pot experiments. This manuscript summarizes and compares these results to evaluate the suitability of different technical approaches to recycle P from wastes into applicable fertilizers. In total, 17 products of recycled sewage sludge ashes (SSA), one meat and bone meal ash, one sinter product of meat and bone meal, one cupola furnace slag, nine Ca phosphates from crystallization or from precipitation, Seaborne-Ca-phosphates, Seaborne-Mg-phosphate, and 3 different struvites were tested in comparison to controls with water soluble P, that is, either single super phosphate (SSP) or triple super phosphate (TSP). Sandy and loamy soils (pH: 4.7–6.8; CAL-P: 33–49 ppm) were used. The dominant test plant was maize. Phosphorus uptake from fertilizer was calculated by the P content of fertilized plants minus P content of unfertilized plants. Calculated uptake from all products was set in relation to uptake from water soluble P fertilizers (SSP or TSP) as a reference value (=100%). The following results were found: (1) plants took up less than 25% P in 65% of all SSA (15 products); (2) 6 products (26%) resulted in P uptake of 25 and 50% relatively to water soluble P. Only one Mg-P product resulted in an uptake of 67%. With cupola furnace slag, 24% P uptake was reached on sandy soil and nearly the same value as TSP on loamy soil. The uptake results of Ca phosphates were between 0 and 50%. Mg-P products from precipitation processes consistently showed a better P supply in relation to comparable Ca-P compounds. With struvite the same P uptake as for water soluble P was reached. The fertilizer effect of the tested P recycling products can clearly be differentiated: TSP = struvite > Mg-P = sinter-P > Ca-P, cupola-slag > thermally treated sewage sludge ashes > meat-and-bone meal ash = Fe-P. Full article