In this paper, we present a phenomenological model that predicts the size distribution of the product issued from impact crushing in function of the rotor strike radius and velocity, the material properties and size distribution of the feed as well as the feed rate. The model is based on the standard matrix representation including classification and breakage matrices. It can be applied to both horizontal- and vertical-shaft impact crushers by means of the corresponding estimations for the average impact energy per unit mass presented here.

We propose a new classification function for impact crushers in the form of a Weibull cumulative distribution. The minimum size of the particles that undergo breakage is assumed to be a function of the impact energy and the feed rate.

The model predictions are compared with experimental data obtained for limestone treated in a pilot-plant hammer crusher.

The dependence of the product size distribution on the rotor velocity is investigated. The influence of the feed rate on the

product size is also simulated.22259

D 2004 Published by Elsevier B.V.

Keywords: impact crushing; standard matrix representation; Weibull cumulative distribution

1. Introduction

During the past few decades, impact crushers have

become widely used machines for comminution

operations because of their high size-reduction ratio,

easy modification of the product size distribution and

a good dcubicT shape of the product. On the other

hand, computer simulations are increasingly used in

the modern design of ore processing plants containing

crushers as a reliable, time- and cost-saving approach.

* Tel.: +32 69 88 42 66; fax: +32 69 88 42 59.

E-mail address: ctp@honet.be.

0301-7516/$ - see front matter D 2004 Published by Elsevier B.V.

doi:10.1016/j.minpro.2004.07.031

Despite their importance, however, impact crushers

received little attention in what concerns the model- 源￥自%六:维;论-文'网=www.lwfree.cn

ling and simulation of their comminution behaviour.

For this reason, the commercial codes for ore

processing simulations still lack specific models for

this type of crushers. There have been some recent

attempts to develop phenomenological models for

impact crushers (e.g., by Czoke and Racz, 1998;

Attou, 1999), but nevertheless, significant amount of

work has yet to be done in this field.

Here we take the standard size distribution model

for cone and jaw crushers developed by Whiten and

White (1979) as a starting point. Because of the

specificity of the breakage process in impact crushers,

S. Nikolov / Int. J. Miner. Process. 74S (2004) S219–S225

this model cannot be used for these machines in its

original form. Impact breakage takes place at a much

shorter time scale compared to the fragmentation

process used in cone or jaw crushers. Hence, the

nature and magnitude of forces as well as the energy

transfer and dissipation related to impact breakage are

very different from the relatively slow breakage by

compression and shear used in other types of crushers.

In order to solve this problem, we replace the

classification breakage function used for cone and jaw

crushers with a new one based on a Weibull

probability distribution. Thus, important parameters

such as the rotor radius and velocity as well as the

feed rate are naturally incorporated in our model. We

also propose estimations for the average impact

energy per unit mass for both horizontal- and

vertical-shaft impact crushers.

The model structure is presented in Section 2,

results are shown and commented in Section 3.

Throughout the text, vectors ( f ) and matrices (C )

BP represents the redistribution of the broken particles

among the predefined size classes.

According to Fig. 1, the particles entering the 环锤式破碎机英文文献和中文翻译:http://www.lwfree.cn/fanyi/20180505/14812.html