Aggregate Production from Waste Stream Using Multi-Stage Separation
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Solution Overview
Problem
Current recycling methods for waste streams like automobile shredder residue (ASR) are inefficient in producing clean aggregate and recovering valuable metals, as they often result in materials with high dirt content and low metal concentration, which reduces their commercial value and environmental benefits.
Innovation Solution
A multi-stage process involving sizing, wet screening, density separation, magnetic separation, eddy current separation, and gravity separation to produce clean aggregate and concentrate metals, specifically using a system that includes first and second density separators operating at 1.6 to 3.2 Specific Gravity, magnets, and eddy currents to segregate and recover ferromagnetic, paramagnetic, and precious metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional single-stage recycling methods are used to process waste streams, then the process is simple and quick, but the aggregate produced has high dirt content and low metal concentration, reducing commercial value
Solution Approach 1:
The recycling process is divided into multiple sequential separation stages, each targeting specific materials with different properties. The first density separator (1.6-2.0 SG) removes lighter contaminants, the second density separator (3.2 SG) concentrates metals, and magnetic separators recover ferromagnetic and paramagnetic metals. This segmentation allows each stage to specialize in removing specific impurities, achieving high aggregate cleanliness through progressive purification.
Solution Approach 2:
Different separation technologies are applied to different material fractions based on their specific properties. Density separation is used for initial cleanup and metal concentration, magnetic separation targets ferromagnetic and paramagnetic metals, and eddy currents remove non-ferrous metals. Each local separation zone is optimized for the specific contaminants present at that stage, maximizing overall separation efficiency.
2Quantity of substance
If traditional recycling methods are used, then the system is simple to operate, but metal recovery is inefficient and commercial value is lost
Solution Approach 1:
The system exploits changes in physical parameters (density, magnetic susceptibility, electrical conductivity) to separate different materials. By adjusting the specific gravity thresholds of the density separators (1.6-2.0 SG and 3.2 SG) and using multiple magnetic separation stages, the process optimizes metal concentration in the aggregate product while maximizing recovery efficiency of valuable materials.
Solution Approach 2:
The system combines multiple separation technologies (density separation, magnetic separation, eddy current separation) into an integrated composite processing system. This composite approach allows simultaneous recovery of different material types (ferromagnetic metals, paramagnetic metals, non-ferrous metals, and clean aggregate) from the same waste stream, improving overall productivity and metal recovery efficiency.
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 effectively increases metal content in the aggregate from over 4% in the waste stream to less than 0.1% in the final product, producing clean aggregate with substantial commercial value and reducing landfill strain.
Implementation Method 1
separating the first group using a first density separator operating at about 1.6 to 2.0 SG into a first heavy fraction and a first light fraction
Implementation Method 2
separating the first heavy fraction using a second density separator operating at about 3.2 SG into a second heavy fraction and a second light fraction, wherein the second heavy fraction contains metals
Implementation Method 3
magnetically separating to recover ferromagnetic metals and paramagnetic metals
Implementation Method 4
using at least two eddy currents; using density separation to recover precious metals and heavy metal concentrate
Data Source
AI summary
A method for preparing clean aggregate from a waste stream including sizing the incinerator combined ash to recover a first material; wet screening the first material with a first screen to recover the material of disparate sizes; and processing each of the groups.