Segmented Roll Crusher for Polysilicon Comminution
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Solution Overview
Problem
Existing methods for comminuting coarsely crushed polycrystalline silicon for photovoltaic applications result in excessive metallic surface contamination and are either laborious or uneconomical, requiring subsequent cleaning and involving complex machine configurations.
Innovation Solution
A roll crusher with a segmented hard-metal roll comprising a cobalt matrix with tungsten carbide, where the hard-metal segments are reversibly fastened on a steel carrier roll, sealed with non-metal-contaminating plastic, and designed for efficient crushing with a specific angle and diameter to minimize contamination and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional jaw crushers are used for comminuting polycrystalline silicon, then the crushing function is achieved, but excessive metallic surface contamination occurs (500 to 1000 ppba)
Solution Approach 1:
The roll is divided into multiple hard-metal segments that can be individually replaced. This segmentation allows the use of highly wear-resistant hard-metal materials on the crushing surface while keeping the carrier roll structure simple and economical, resolving the contradiction between crushing effectiveness and contamination control.
Solution Approach 2:
The invention uses composite hard-metal segments consisting of tungsten carbide particles in a cobalt matrix bonded to a steel carrier roll. This composite structure provides both the hardness needed for effective crushing and controlled contamination levels, while the reversible form-fit connection allows easy replacement of segments.
2Ease of manufacture
If roll crushers are used with conventional rolls, then crushing is achieved, but the machine becomes very complex and expensive
Solution Approach 1:
The roll is segmented into multiple independent hard-metal segments that can be individually replaced without affecting the entire roll structure. This simplifies maintenance and reduces machine complexity compared to conventional designs requiring complete roll replacement or complex adjustment mechanisms.
Solution Approach 2:
The hard-metal segments are reversibly connected with a form fit, allowing them to be dynamically replaced or adjusted as needed. This reversible connection system provides flexibility and ease of maintenance while maintaining a relatively simple overall machine structure.
3Productivity
If coarsely crushed polycrystalline silicon is comminuted without cleaning, then productivity increases, but contamination levels become too high for photovoltaic applications
Solution Approach 1:
The invention changes the material parameter of the crushing surface by using hard-metal segments with specific properties (tungsten carbide in cobalt matrix) that produce lower contamination levels. This allows the material to be comminuted directly without intermediate cleaning steps while maintaining purity suitable for photovoltaic applications.
4Reliability
If hard-metal segments are permanently fixed on the carrier roll, then structural stability is improved, but maintenance and segment replacement become laborious
Solution Approach 1:
The hard-metal segments are connected with a reversible form fit that provides structural stability during operation but allows easy removal and replacement when needed. This dynamic connection system resolves the contradiction between maintaining reliable structural integrity during crushing and enabling simple maintenance operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution allows for low-cost, low-contamination comminution of polycrystalline silicon with reduced manual processing steps, achieving a reproducible fragment size distribution and significantly lower contamination levels, thereby eliminating the need for subsequent cleaning.
Implementation Method 1
a roll crusher (10) comprising a roll (20) which rotates with a shaft (3), wherein the roll (20) comprises a carrier roll (2) of steel and a number of hard-metal segments (1)
Implementation Method 2
the hard-metal segments (1) consist of a cobalt matrix in which tungsten carbide is incorporated
Data Source
AI summary
Polysilicon is crushed with a minimum of manual and machine crushing steps by utilizing a large diameter roll crusher, the circumferential crushing surface of which is formed of a plurality of reversibly mounted, close fitting hard metal plates. Reproducible crushing along with such low metal contamination that subsequent cleaning of the crushed polysilicon is not necessary are both obtained.