Dry granulation, as a new process of molten BF slag treatment, is an attractive alternative to water quenching. The medium in the heat exchanging process is air which results in low efficiency. Therefore, the technique for waste heat of molten BF slag recovery is exploited. The waste heat is recovered by waste heat boiler which produces high pressure steam for generating electricity. The heat transfer characteristics of apparatus were investigated. The results show that the overall heat transfer coefficient can reach 111W/ (m2•K) and the heat recovery can reach 90% at most. If slag granule diameter is less than 2.5mm and descending velocity is higher than 1.0mm/s, the cooling rate of slag granule is over 10K/s. Then slag granules can be used as nicer materials to produce Portland cement. When slag granule descending velocity equaled to 1.1mm/s and the flux of water equaled to 0.15m3/h, small quantity of steam appeared in the first and second row tubes. They proved the feasibility of this technique. The application of this technique has a significant social meaning.