Abstract: In order to verify the effect of crushing modes on grinding speed and Bond ball grinding work index， the grinding dynamics test and Bond ball grinding work index test were respectively carried out by using the jaw crusher product， cone crusher product and high pressure roller grinding product of a magnetite concentrator. The results showed that:①the grinding effect of high pressure roller mill is the best， followed by the cone crusher product and the jaw crusher. The grinding speed of the same crushing product decreases with the increase of grinding time. For different crushing products， with the increase of grinding time， particle properties and grinding speed are gradually uniform and close to each other. And the influence of crushing modes on grinding speed is gradually unconspicuous. ②The test of Bond ball grinding work index showed that when the particle size of the grinding product is larger than 0.10 mm， the crushing modes has a significant impact on the energy consumption of the grinding product， and the high pressure roller grinding product is the most energy-saving. When the particle size of the grinding product is less than 0.10 mm， the impact of crushing modes on the energy consumption of the grinding product is reduced. The uasage of high pressure roller mill in crushing process is beneficial to increase the processing capacity of mill and reduce the grinding energy consumption.

Key words: crushing way, magnetite, grinding speed, Bond work index of ball mill