Pebble mill also belongs to autogenous grinding category, but it is different from ore autogenous grinding. In earlier times, pebble media is pebble at river coast, and subsequently, ore block is used as media. Since earlier 20 century, pebble mill was successfully applied to industrial production, which was a success after enlarging capacity to a large extent and finally production ability reached the similar capacity of ball mill. Although used in industrial production, pebble mill didn't develop popularly. The reason for which is that the grinding process was not simplified, besides, it added media making system. However, pebble mill still exists up to now, because its products are no iron pollution, and the selection index is relatively good, especially in Uranium deposit in ore product treatment. Pebble mill application is rather widely, which is able to decrease acid consumption in acid leaching. Wet grid ball mill is the similar product, but pebble mill is a little longer than it.
Generally, pebble mill is used as secondary grinding equipment in rod mill and autogenous grinding, which is used for fine grinding, and seldom used for coarse grinding. Due to small power consumption, low production cost, saving metal material (such as grinding media), being able to avoid metal pollution, etc. pebble mill is widely used in ore dressing, especially available to special material requirement. Since 1980s, Nordic developed and promoted a type of broken milling process called Autokump, which was available to general Rod mill machine or ball mill (such as φ 4.0M X6.0M, and φ 3.2 m X4.5 m) as block mill machine. Instead of metal stick or ball, it uses large ore greater than 1OO mm as grinding media to deal with material less than 30 mm; The particle size which is between 30mm and 100mm, which is so-called difficult milling particle as gravel mill media. In order to facilitate the discharging, block mill discharging port is a little larger. In order to enhance productive capacity, its diameter is much larger than general mills.
