Every crusher needs an upgrade from time to time
Cement plant operators worldwide face the same challenges in raw material crushing. The service lifetime of the rotors in the various (several, different) crushing plants plays a central role in their economic efficiency. The reasons for downtimes are manifold.
The rotor has a significant impact on the crusher lifetime and therewith on the ongoing production costs, regardless of the crusher type. All over the world, customers are experiencing the problems of overstressed designs. An incorrectly selected rotor design repeatedly leads to excessive vibrations and thus to cracks in the rotor body, loose rotor disks, and often ends in the failure of the crusher. The down streamed performance issues can be even bigger.
In addition to the design, the selection of the right wear part qualities, wear volumes and designs (hammers, blow bars, crushing segments) also influences the service life of a rotor to a particular extent. In the case of rapid wear, the base material is attacked just as quickly and can lead to irreparable damage. This can also occur with new rotors.
Along with the mechanical influences, changes in the raw material also have a significant effect on the service life. As quarrying progresses, there are often changes in the hardness, moisture and chemical composition of the quarried rock for which the crusher is not designed.
From time to time, however, there are also process-related reasons (incorrect rotor speed, insufficient number of blows, in the case of hammer crusher the center distance between the rotors or the height of the anvil).
Possible optimizations
The problems listed above are often interlinked. With different design variants for versatile applications, thyssenkrupp Polysius is able to respond individually to each case and create a technically optimal solution.
For example, thyssenkrupp has various steel welded construction and cast variants in its portfolio for its hammer and impact crusher rotors. Depending on where the plant’s individual problems lie, the company’s experts work with its customers to decide what the best solution is for the crusher in detail.
On the part of the customer (from customer side) it is very important that thyssenkrupp is given as (to get) much information as possible and that the current problems are described in detail. In addition, detailed information is required on the raw material, grain sizes, raw material moisture and the compressive strength of the raw material. Operational data such rotor speed, installed motor power, product size, etc. is also relevant. Based on this information, thyssenkrupp Polysius is able to offer its customers a customized optimization.
Every crusher needs an upgrade from time to time, due to changed raw material, overloading of the machine or production changeovers. For this reason, the Beckum-based cement and lime plant specialist not only focuses on its own crushers, but also offers services for all crusher available on the market.
Example
A specific example are the roll crushers. Here, a new design with exchangeable crushing segments has been developed in recent years. The previous design consisted of a pipe construction. This pipe design rotor could only be replaced by time-consuming and costly dismantling of the entire upper part of the crusher. The crusher segment design (see Figure 1) now makes it possible to dismantle and reassemble these segments relatively easily without dismantling the upper crusher housing. This makes their cost-effective reconditioning – for example in the company’s own workshop – possible.
In addition, thyssenkrupp Polysius has carried out modifications on various crusher types (hammer crushers, impact crushers, roll crushers, sizers) in the recent years. In close cooperation with its global customers, it has succeeded on several occasions in bringing even obsolete machines “back to life” and not only maintaining stable operation but also optimizing them in many areas. The optimization has often been reflected in machine availability.
Novelty
As the latest innovation, the rotor design of the mammut® rotor (single-shaft hammer crusher) was improved. Using current manufacturing technologies, thyssenkrupp Polysius succeeded in transferring a well-known and proven system into the modern era. For the customers, this means: a cost-effective and stable alternative to replacing the entire crusher.
