Pyrogenic Silica Compaction for High Bulk Density
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Solution Overview
Problem
Pyrogenically prepared silicon dioxide is difficult to compact without binders due to its dry nature and high surface charge, leading to challenges in achieving high bulk density and defined compactates, with existing methods resulting in low density and high dust content.
Innovation Solution
A process involving preliminary de-aeration and compaction using rolls to produce crusts with controlled bulk density, which are then broken and sieved to achieve a tamped bulk density of 185 to 700 g/l, allowing for stable and flowable products with low dust content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pyrogenically prepared silicon dioxide is compacted without binder, then the product maintains high purity and redispersibility, but the bulk density remains low and defined compactates cannot be achieved
Solution Approach 1:
The patent applies preliminary action by pre-compressing the pyrogenically prepared silicon dioxide in a first compression device before final compacting. This pre-compression removes air gaps and prepares the material structure, enabling subsequent formation of defined compactates with high bulk density without requiring binders.
2Ease of operation
If pyrogenically prepared silicon dioxide is compacted to high bulk density, then the product achieves good flowability and metering capability, but dust content increases
Solution Approach 1:
The patent uses an intermediary approach by introducing a small amount of water (0.1-5% by weight) as a temporary mediator during compacting. This water acts as a lubricant that reduces dust generation during compression while maintaining the ability to produce flowable, high-density compactates. The water is subsequently removed, leaving the pure silicon dioxide product.
3Quantity of substance
If pyrogenically prepared silicon dioxide is compacted using conventional methods, then some bulk density increase is achieved, but the tamped bulk density remains below 180 g/l and defined particle size cannot be controlled
Solution Approach 1:
The patent applies segmentation by dividing the compacting process into two distinct stages: first compression in a first device to achieve initial densification, followed by second compression in a second device to achieve final high bulk density. This segmented approach enables both high tamped bulk density (185-700 g/l) and controlled particle size definition that cannot be achieved with single-stage conventional methods.
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 process achieves a high and consistent bulk density of 185 to 700 g/l, providing a stable, flowable, and low-dust product with defined particle size, suitable for various applications, while minimizing dust generation and maintaining redispersibility.
Implementation Method 1
compacting of pyrogenically prepared silicon dioxide without binder is difficult because pyrogenically prepared silicon dioxide is very dry and there are no capillary forces that can bring about binding of the particles
Implementation Method 2
A process involving preliminary de-aeration and compaction using rolls to produce crusts with controlled bulk density
Data Source
AI summary
Pyrogenically prepared silicon dioxide is compacted to give crusts, in that it is subject to preliminary de-aeration, and is compacted to give crusts, and the crusts are broken and, if appropriate, classified. The tamped bulk density (to DIN EN ISO 787-11) of the silicon dioxide compacted to give crusts is from 185 to 700 g/l. It can be used as filler in rubber mixtures.