Properties of Concrete Made from Cupola Furnace Slag and Recycled Construction Aggregates

The replacement of traditional constituents of concrete with waste has garnered a lot of interest due to the increasing demand for natural resources used in concrete production. Hence, this study presents the outcome of an experimental investigation on the effect of partial replacement of Ordinary Portland Cement (OPC) at percentage levels of 0% to 25% in steps of 5%, partial and complete replacement of sand and granite in the percentage of 0 to 50 in steps of 10% with cupola slag and recycled construction aggregates. The fresh and hardened properties of concrete such as workability, compressive strength, and microstructural characteristics were assessed. The test results showed a decrease in workability as the percentage replacement of cupola furnace slag (CFS) and recycled construction aggregates (RCA) increases. Concrete produced at 28 days from the partial replacement of cement and sand with cupola slag has an optimum compressive strength of 20.37 N/mm2 at 10% and 22.81 N/mm2 at 20%, resulting in improved strength of 29.4% and 56.82%, respectively when compared with the control. In contrast, granite’s partial replacement with coarse cupola slag and complete replacement of sand and granite gave a lesser compressive strength when compared with the control samples at 7, 14, 28, and 56 days. The porosity of the concrete with optimum compressive strength from each mix was studied using microscopic and image analysis. The result showed that the addition of cupola slag in granulated and fine forms decreases the porosity, hence leading to higher compressive strength.

ANALYSIS AND THERMODYNAMIC STABILITY OF NUCLEI IN SPHEROIDAL GRAPHITE IN Fe–C–Si ALLOYS

The paper describes the graphite nuclei constitution for spheroidal graphite cast iron melted in a cupola furnace, which is treated by the addition of magnesium and inoculated with a barium-based inoculant. Two samples of spheroidal cast iron were analysed, differing only in tin content. Field-emission scanning electron microscopy (FE -SEM) with energy-dispersive X-ray spectroscopy (EDS) was used to analyse the nuclei. The thermodynamic calculation of the phase equilibria and the associated free formation energies of the alloys were calculated and compared with metallographic observations. It was found that the nuclei in the spheroidal graphite are different in shape and composition. Spherical and rectangular ones were found, and in many cases the porosity was present at the nuclei. The nuclei consisted of different compounds such as (Mg,Ca)S, MgO, (Mg,Al,Si)N. The amount of Sn only affected the pearlite content, and there were no Ba and rare earths present in the nuclei.

Cupola Furnace Design and Fabrication for Industrial Development

The Cupola Furnace Capacity of 450 kilograms per hour was designed and fabricated using locally sourced raw materials which include pig irons, crop ends and foundry shop returns, and ferroalloys for the production of quality cast iron which depends on the customer’s demand. Metallurgical coke is the main fuel source employed for the production processes. The design parameters were analyzed and the metallic shells were then fabricated into four sections to allow proper lining. A mild 5 mm thick steel sheet was collected, marked out according to the required specification. slit and formed into cylindrical shapes. The sections were coupled and joined together through a welding process. Sodium silicate was used as a binder to make them bondable to the interior sections, the internal configurations were first lined with asbestos sheets measured 5 mm thick. with a less dense insulating refractory material. Fireclay refractory bricks were used for furnishing as they directly interfaced with the molten metal, while the flame blower was connected, assembled, and erected in the different segments. Financial analysis was performed to give a general overview of the cost of manufacturing and building a cupola furnace produced locally at N1,467,266.00, which is relatively cheap compared to the imported ones. The technical details were given for the production processes. The raw materials used were sourced locally as they are readily available in quantum and are essential to the government policies on adding values to the production processes by using these materials to promote the addition of these materials for the creation of local content.

Dually Operated Control Cupola Furnace With Maintaining Constant Air Blast for Improving Production Gain of Iron

Cupola furnace is the most commonly used for the melting of ferrous metals and alloys. The key challenge in this paper is variation of air blast which lead to productivity loss and moreover affects the small scale industries. In order to overcome the above key challenge our work has proposed a Dually Operated Control Cupola Furnace which states that constant air blast can be obtained by controlling manually as well as automatic. Manual operation is obtained by maintaining constant Motor-Torque-Speed-Ratio using inverter driven blower along with space vector pulse width modulation. Automatic operation inhabits a feedback control system using nonlinear model predictive controller which is operated on control valve driven blower. Automatic operated cupola furnace obtains a prediction value for obtaining the productivity gain based on number of experimental observations and overall gives the required constant air blast by considering blast volume, blast temperature and oxygen enrichment. Thus our model enhances the system performance by achieving productivity gain in terms of melting rate and super heating temperature.

Design, Fabrication and Construction of Cupola Furnace for Metallurgical Industries

A 350 kilogram per hour capacity Cupola Furnace was designed and fabricated from locally available materials for the production of cast iron using pig iron, oily or contaminated steel scraps, foundry returns and fluxes. The main fuel used is metallurgical coke. After analyzing the design parameters, the metallic shells were fabricated in four segments for easy lining: the stack zone, preheating zone, combustion zone and the hearth. Mild steel sheet of 4 mm thickness was procured, marked out as per the design drawing, sliced, rolled into cylindrical shapes and welded together at each seam. The internal configuration was lined first with asbestos paper measuring 4 mm thick using water-glass to enable it adhere to the internal shell of the segments, thereafter, a less dense insulating refractory material was used and finally fireclay refractory bricks were used for lining as they interface directly with the molten metal. The various segments were then assembled and erected with the blower connected to the combustion zone. The research work also contains the materials and components bill.

Potential for Developing Biocarbon Briquettes for Foundry Industry

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.