Abstract: The semi-automatic grinding products of Baima Iron Mine in Tianjia Village were transported to the grinding plant by 6.5 km pipeline， which conveying particle size was -3 mm. Due to unreasonable design parameters at the initial stage of production， the pipeline was often blocked and cannot run normally. Through the analysis of the granularity， flow rate and velocity of ore pulp， some researches and improvements were carried out. The results show that the coarse particle size of export pulp decreases and the fine particle size increases， and the flow rate and velocity decrease and the concentration increase to form blockage in the conveying process. On this basis， the conveying system was optimized and transformed: the mesh parameters of the semi-autogrinding-sieve plate were adjusted to 2.5 mm×12 mm， the diameter of the impeller of the first stage pump was changed from 965 mm to 990 mm， the pump pool structure was transformed from flat bottom four corners to three-sided slope structure， and the conveying system ran smoothly after the transformation. In order to improve the processing capacity of semi-autogenic mill as much as possible， the parameters of semi-autogenic mill after optimization， slurry pipe size， slurry flow rate and velocity were investigated. The results show that the slurry concentration is improved after optimization， and the conveying flow rate and velocity exceed the design indexes， ensuring the stability of pipeline transportation. To study the feasibility of conveying system to further optimize and carry out the experimental study of the rheological properties of the pulp， test the original pulp body sedimentation characteristics， different concentrations of the rheological properties of pulp， the critical flow velocity， friction loss are analyzed and calculated by the comprehensive analysis on the impact of parameters such as concentration， particle size on transport， on the basis of adjust sieve plate size for 2 mm × 12 mm. Adjust two pump impellers of the first pump station to 870 mm and 980 mm respectively. After optimizing the parameters of the conveying system， the average time of the semi-automatic grinding platform is 613 t/h， and the flow rate of the pipeline is 3.44 m/s. It realizes the stable operation of the long-distance pipeline conveying of coarse slurry， which is of reference significance to the pipeline conveying of mining enterprises.

Key words: semiautomatic grinding products, coarse ore pulp, pipeline transportation, rheological properties of slurry