Abstract: In order to expand the production capacity of Makeng Iron Mine，the high pressure grind⁃ ing roller and auxiliary system were added between the original three stage crushing with single closed circuit stage and stage grinding-low intensity magnetic separation processes.The application practice showed that the addition of new process system improved the processing capacity of ore crushing equipment by coarsening the particle size of secondary crushing and third crushing products，and the treating capacity of concentrator was increased by 1.4 times and it could not only produce two million tons of construction sand and stone every year，but also ensure the grade of ore to be grinded，greatly improving the comprehensive utilization of ore resources by increasing the ore quantity of underground mining and multi-stage preconcentration.The high efficiency preconcentration and discarded tailings before grinding，which greatly reduced the ore quantity entering the grinding and concentration system，the concentrate capacity of the single series ball milling system had been increased from 53.52 t/h to 100.47 t/h.The selective crushing of high pressure grinding roller and wet pre-discarding the tailings of coarse particles before grinding had improved the magnetic separation effect，making the iron concentrate grade increase from 63.68% before transformation to 65.42%. The interlaminar crushing of the high pressure grinding roller in confined space not only has low noise，but also has less dust，which improves the working environment and reduces occupational hazards. The electricity consumption of iron concentrate production decreased by 4.6 kWh/t，and the steel ball consumption decreased by 246 g/t，and energy conservation and emission reduction achieved outstanding results.

Key words: high pressure grinding roller, production increasing and quality improving, energy saving and consumption reducing