As is well known, the productive capacity of the mill will be increased with the increment of the rotation speed. But the mill can hardly grind when the rotation speed of the mill reaches or exceeds the critical rotation speed. If the productive capacity of the mill increases continually with the increment of the rotation speed above the critical rotation speed, the developing objective that the small-scale mill has large-scale productive capacity is attained. In view of the objective, Kunming university of science and technology has developed a new kind of mill-the ultracritical rotation speed mill and obtained the invention patent right, and the patent number is ZL99127837.2.On the basis of consulting a vast amount of scientific data, the prototype of the ultracritical rotation speed mill is designed and made. Combining the distinctively grinding characteristic of the ultracritical rotation speed mill, this paper has made the experimental research of parameter of the prototype, the kinematics research of the ball mediums and the kinetics experimental research of the prototype.The results of the experimental research of parameter of the prototype show that the favorable ore weight and the favorable pulp density is 7Kg and 65%. When the rotation speed of the prototype is 54r/min, the content of the rough size is higher. When the rotation speed of the prototype is lOOr/min, the content of the rough size is lower than that of 54r/min and the content of the fine size is raised greatly. When the rotation speed of the prototype is 200r/min, the grinding velocity is 6 times as much as that of lOOr/min. The experimental results of fine grinding of the prototype indicate that the effect of fine grinding is very obvious.The results of the kinematics research of the ball mediums show that the ball mediums in the mill go mainly through three steps: uniform circumference motion, no friction motion on the surface of the guiding board and parabola motion. The parabola equation and the formula of the pounding velocity of the ball mediums are extracted:.The analyzing and calculating results of the pounding velocity show that the pounding velocity is linear with the millradius and the rotation speed. The pounding frequency of the ball mediums at the unittime is also extracted K = . It has no concern with the mill radius, but it isconcerned with the rotation speed of the mill by the direct proportion and the constantof the direct proportion is .By the kinetics experimental research of the prototype, the grinding kinetics equation under the circumstances of different ultracritical rotation speeds andmediums filling rate are extracted R(t) = 100exp[-(a0 +a,O(t"+t'ln(''))]. According to these equations, the scattering rate-/?(0 at the rational time and the size to be grinded under the circumstances of different ultracritical rotation speeds and mediums filling rate can also be extracted. The analyzing results of the kinetics equations show : (l)With the increment of the rotation speed, the grinding velocity will be increased greatly. The faster the rotation speed increases, the more obvious the trendency is. (2)With the increment of the medium filling rate, the grinding velocity will also be increased. And at the limit of the less mediums filling rate, the increment of the grinding velocity is much more obvious with the increment of the mediums filling rate. (3)With the lengthening of the grinding time, the grinding velocity will be decreased. When the grinding time is longer, the trend is more obvious.The results of a large number of experimental and analyzing research show that the ultracritical rotation speed mill has grinding characteristics as follows: (l)The productive capacity of the mill is raised in multiple at the unit volume. (2)The mediums filling rate of the mill is descended and the size of the mediums is smaller than that of the conventional mill. (3)The ultracritical rotation speed mill is suitable for not only rough grinding but also fine grinding. |