Slag Filler Production via Fraction Removal and Milling
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Solution Overview
Problem
Current fillers for construction materials, such as asphalt and concrete, face challenges due to the limitations of natural resources like limestone and the unsuitability of γ-dicalcium silicate-containing slags, which absorb excessive water, affecting workability and durability, and pose environmental concerns due to high metal content in stainless steel slags.
Innovation Solution
A process that involves removing the finer fraction from γ-dicalcium silicate-containing slags and finely milling the coarser fraction to produce a filler with a lower γ-dicalcium silicate content, achieving a suitable particle size and water content for use in bituminous and hydraulic construction materials, while allowing for metal recycling and reducing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If γ-dicalcium silicate-containing slag is used as filler, then alternative to limestone is provided, but water absorption increases excessively
Solution Approach 1:
The patent removes the finer fraction containing γ-dicalcium silicate from the slag material through classification processes (sifting, screening, or air classification). This extraction eliminates the water-absorbing component while retaining the coarser fraction suitable for filler applications, thereby resolving the contradiction between providing an alternative filler source and controlling water absorption.
2Quantity of substance
If finer fraction is removed from slag, then water absorption decreases, but particle size distribution changes
Solution Approach 1:
The patent applies fining processes (milling, grinding, or crushing) to the coarser fraction after removal of the finer fraction. This changes the particle size parameters of the remaining material to achieve a suitable size distribution for filler applications, thereby resolving the contradiction between reducing water absorption and maintaining appropriate particle size distribution.
3Ease of operation
If limestone is used as filler, then good workability is achieved, but natural resource consumption increases
Solution Approach 1:
The patent recovers and utilizes the coarser fraction of slag material (after removing the finer γ-dicalcium silicate-containing fraction) as a filler alternative to limestone. This transforms waste slag into a useful filler product that can provide good workability in construction materials while reducing consumption of natural limestone resources.
4Object-affected harmful factors
If stainless steel slag is recycled, then environmental impact reduces, but metal content contamination increases
Solution Approach 1:
The patent removes the finer fraction which contains the majority of metal contaminants from the stainless steel slag. By extracting this fraction through classification processes, the remaining coarser fraction has reduced metal content while still providing environmental benefits through slag recycling, thereby resolving the contradiction between reducing environmental impact and minimizing metal content contamination.
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 results in a filler that enhances the workability and durability of construction materials, reduces water absorption, and facilitates the recycling of stainless steel slag, providing an economically and environmentally advantageous solution for filler production.
Implementation Method 1
the coarser fraction is milled so as to provide a filler of which at least 50% by weight, preferably at least 60% by weight, is formed by particles not bigger than 63 μm
Data Source
AI summary
The present invention relates to a process for preparing, starting from a slag material, a filler for construction materials which contain bitumen or a hydraulic binding agent. The slag used to prepare the filler contains γ-dicalcium silicate. The process comprises the step of removing from the slag material a finer fraction formed by particles of a size between 0 and at least 0.75 mm so as to reduce the γ-dicalcium silicate content of the slag material; and the step of finely milling at least a portion of the remaining coarser fraction of the slag to obtain the filler. The invention also relates to the obtained filler, to the use thereof for preparing construction materials and to concrete or mortar compositions and asphalt compositions containing the filler. By removing the finer fraction from the slag material, a filler is obtained which has a considerably lower water content so that it becomes suitable for use in asphalt or concrete or mortar compositions, in particular in self-compacting concrete compositions.