Combined direct reduction technology of blast furnace gas ash and refractory low-grade iron ore in tunnel kiln

The invention provides a combined direct reduction technology of blast furnace gas ash and refractory low-grade iron ore in a tunnel kiln. The combined direct reduction technology mainly comprises the following processing steps: (1) burdening and mixing the iron ore with grain sizes of 0-3mm and the blast furnace gas ash so as to obtain fine-graded materials; grading the iron ore with grain sizes of above 1mm according to different grain size ranges, burdening and mixing the iron ore and reduced coal in the same grain size range so as to obtain coarse-graded materials; (2) sequentially laying the fine-graded materials and the coarse-graded materials on a fire-resistant thermal conducting plate of a kiln car of a tunnel kiln from top to bottom; and (3) placing the materials in the tunnel kiln along with the kiln car so as to carry out high temperature reduction. The combined direct reduction technology has the advantages that the blast furnace gas ash is effectively utilized, and the utilization efficiency of carbon in the blast furnace gas ash is greatly improved; by adopting a layering distribution step-by-step oxygenation reduction method, the metallization ratio of iron ore direct reduction is increased, and the reduction time is shortened; and the iron grade of metallizing iron powder produced by the technology reaches above 84%, and the metallization ratio reaches above 88%.