Multi-Stage Foundry Sand Regeneration Process
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Solution Overview
Problem
The foundry industry faces economic and environmental challenges due to uneconomical and energy-intensive internal regeneration processes for used sand, leading to high disposal and transport costs, environmental pollution, and the need for large landfill areas, with existing methods not delivering desired sand quality or reducing waste effectively.
Innovation Solution
A multi-stage crushing process using a hammer mill, disc mill, and pin mill followed by classification, with pre-classification and thermal post-treatment as needed, to deagglomerate and separate binder shells from sand particles, optimizing process parameters for maximum sand quality and minimizing residues and waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If internal regeneration processes are used for used sand, then sand recycling is achieved, but the process is uneconomical and energy-intensive
Solution Approach 1:
The regeneration process is divided into multiple sequential stages: coarse crushing, fine crushing, classification, and optional thermal treatment. Each stage uses equipment optimized for its specific function, allowing the process to be tailored to the actual contamination level and avoiding unnecessary energy-intensive steps for lightly contaminated sand.
Solution Approach 2:
The process parameters (crushing intensity, classification mesh size, thermal treatment temperature) can be adjusted based on the contamination level and sand type. This flexibility allows optimization of energy consumption while maintaining regeneration effectiveness for different sand conditions.
2Manufacturing precision
If thermal treatment is applied to remove organic binders, then sand quality is improved, but energy consumption increases
Solution Approach 1:
Thermal treatment is applied selectively and partially - only when contamination levels require it. The process allows mechanical regeneration alone for lightly contaminated sand, using thermal treatment only as needed to achieve the desired sand quality, thus avoiding excessive energy consumption.
Solution Approach 2:
Mechanical preprocessing (crushing and classification) is performed before thermal treatment to remove easily separable contaminants and reduce the burden on thermal processing. This preliminary mechanical action reduces the energy required for subsequent thermal treatment while maintaining final sand quality.
3Object-affected harmful factors
If used sand is disposed of in landfills, then environmental pollution is reduced, but disposal costs and transport costs increase
Solution Approach 1:
The process recovers reusable sand fractions from used foundry sand through mechanical and thermal regeneration, separating them from contaminants that require disposal. This maximizes the quantity of sand recovered for reuse and minimizes the volume requiring costly landfill disposal and transport.
4Manufacturing precision
If multi-stage crushing is applied to remove binder shells, then sand quality is improved, but device complexity increases
Solution Approach 1:
The crushing process is segmented into distinct stages (coarse crushing, fine crushing) with different equipment optimized for each stage. This segmentation allows each piece of equipment to be relatively simple and specialized, while the overall system achieves high sand quality through the coordinated sequence of 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
This approach produces high-quality reusable sand fractions, reducing disposal costs and landfills, increasing foundry profitability, and minimizing thermal processing needs, while ensuring environmentally friendly sand recycling.
Implementation Method 1
hammer mill
Implementation Method 2
disc mill and pin mill
Implementation Method 3
classification
Implementation Method 4
thermal treatment by burning out the organic binder and components
Data Source
Figure 1
AI summary
The invention relates to a method for processing and reusing foundry waste sands, wherein the waste sands are subjected to mechanical breakdown by comminution and subsequent classification. The invention aims to determine the optimal operating point of the regeneration plant, taking into account maximum regenerate quality from various feed sands while simultaneously reducing the amount of residual material and waste. The intention is to achieve complete breakdown of the feed sand fraction using a commercial comminution method by varying the possible process parameters and thereby deagglomerating the binder shells from the sand particles.According to the invention, this is achieved by subjecting the foundry waste sand to a multi-stage comminution grinding process, wherein: • in a first comminution stage, the foundry waste sand is deagglomerated and partially separated marginally from the binder mechanically, • in a second comminution stage, the isolated forming sand particles are freed from their binder shells, and • in a third comminution stage, the remaining binder shells are removed, the comminution of the foundry waste sand is subsequently subjected to classification, wherein the coarse material is transported as regenerate or recyclate to a storage unit and the fine material is sent for disposal and/or landfilling.