[建] convert pig iron into steel by bessemer process

yòng zhuàn lú liàn shēng tiě chéng gāng ㄩㄥˋ ㄓㄨㄢˋ ㄌㄨˊ ㄌㄧㄢˋ ㄕㄥ ㄊㄧㄝˇ ㄔㄥˊ ㄍㄤ