The work-surface of refractories of long-campaign cupola is increasingly being switched from carbon bricks to monolithic to improve performance. In this report, we describe the characteristics of monolithic refractories and describe the issues faced in realizing longer-term operations.

  Three cup thermal analysis is a good method for predicting chill depth, tensile strength, and graphite type in gray cast iron. However, it cannot be used for ductile cast iron due to several reasons. For this reason, we have developed a method for investigating the graphite eutectic temperature (hereafter T_EG) and cementite eutectic temperature (hereafter T_EC) in ductile cast iron, from the chemical composition of molten metal as follows ;

T_EG ＝ 1149.1 (℃) ＋ 4.7Si% － 4.0Mn% － 44P% ＋ 2.7Cu% ＋ 1.0Ni% ＋ 1.8Co% ＋ 13.9Al% － 17.7 Mo% － 10.5Cr% － 9.3Sn% － 5.2Sb% － 6.1W% － 3.7Nb% － 14.8V% － 80.3B%

T_EC ＝ 1142.6 (℃) － 11.6Si% － 0.75Mn% － 46.2P% － 1.4Cu% － 1.1Ni% － 0.7Co% － 1.8Al% － 14.5Mo% ＋ 5.9Cr% － 6.0Sn% － 5.1Sb% － 2.8W% ＋ 0Nb% ＋ 3.3V% － 26.0B%

  Using the cooling curve of 1 cup and the above equations, we calculated eutectic graphitization ability (hereafter EGA). We investigated if this one cup thermal analysis can be used to predict the quality of molten metal (graphite nodule count and shrinkage tendency) correctly even in ductile cast iron before it is poured.

  The graphite nodule count (N) of CE cup T.P. is determined by EGA (＝ ΔT₁ × 100/ΔT_E) as follows : N ＝ 6.13 × (ΔT₁ × 100/ΔT_E) － 126 In addition, when EGA exceeds 90%, the shrinkage tendency parameter (θ) becomes low near 55° which is that of gray cast iron. Consequently, one cup thermal analysis is a good system for predicting the quality of molten metal (graphite nodule count and shrinkage tendency) correctly in ductile cast iron before pouring.

  Coal cokes made in China are used mainly for melting metal in cupola. Due to the high sulfur content of the coal coke, quality is a problem which causes costs to rise. Thus, there is a need to substitute it with high quality low cost coke. Recently, biocoke is drawing attention as coal coke substitute. Biocoke is an environment-friendly biomass fuel that can be made from almost any photosynthetic plant, including what had been considered as waste materials. In Aomori, there are unused biomass such as, apple, rice husks, pruned branches of apple and cedar trees, etc. which can be used as raw material of biocoke. In this research, biocoke made four kinds of biomass raw materials were made. The characteristic and compressive strength of the materials were studied at room temperature and 973K. The sulfur amount of the four kinds of biocoke was less than 0.13%, and ash content was less than 14.0%. When the formation temperature increased to 423K from 383K, the specific gravity of the biocoke increased. When the specific gravity of biocoke increased, the compressive strength at room temperature also increased. The compressive strength of biocoke made of rice husk was the largest at 2.2MPa.

  Coal cokes made in China are mainly used for cupola melting. Due to the high sulfur content of the coal coke, quality is a problem, and there is a need to substitute it with high quality coke. Recently, biocoke made from apple pomace is attracting attention as a coal coke substitute. In this research, biocoke using apple pomace was made and the compression strength was measured. Meting test of the biocoke was performed using a small cupola, and the chemical composition and mechanical properties were measured. In an experiment on the compound biocoke in which bentonite was added to apple pomace, the compression strength was 16MPa when added with 3% bentonite. When melted using a 0.7 tons cupola, operation of cast iron melting was possible at the substitution rate of 10 to 40% of biocoke. The carbon amount and silicon amount did not change with time. In case of cupola melting, the amount of manganese decreased using compound biocoke with bentonite or slaked lime. When the substitution rate of biocoke was increased, the sulfur amount of the cupola molten metal decreased.