High-Throughput Plastic Recovery Using Multi-Stage Gravity Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in recycling plastics lies in the efficient separation of various types of plastics due to their similar densities, leading to incomplete purification and economic viability issues, particularly in waste streams like automobile shredder residue and electronic waste, where materials like rubber, wood, metals, and glass complicate the segregation process.
Innovation Solution
A method involving sizing, comminution with ball or rod mills, and multi-stage gravity separation at specific specific gravities (SG) to separate plastics, including steps at 1.0 SG, 1.15 SG, and optionally 1.1-1.2 SG, with additional processes like magnetic separation and color sorting to achieve precise separation of plastics like ABS and PS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If gravity separation is used to separate plastics by density, then plastics can be separated into different streams, but complete purification is complicated due to the diversity and multitude of plastic types and grades involved
Solution Approach 1:
The gravity separation process is divided into multiple stages with different specific gravity values (first stage at 1.0 SG, second stage at 1.15 SG). Each stage separates plastics into different density fractions, allowing progressive purification. The first stage recovers lighter plastics while the second stage recovers denser plastics, achieving complete separation through segmented processing rather than a single stage.
Solution Approach 2:
The system changes the specific gravity parameter between separation stages. By adjusting the specific gravity from 1.0 in the first stage to 1.15 in the second stage, the system adapts to separate different plastic types and grades. This parameter change enables the system to handle the diversity of plastic materials and achieve complete purification.
2Manufacturing precision
If multiple separation methods are applied to achieve complete purification, then plastic separation improves, but the process complexity and cost increase
Solution Approach 1:
The gravity separation system uses the inherent density differences between plastic types and grades to achieve separation without requiring external intervention or complex additional equipment. By strategically selecting specific gravity values (1.0 and 1.15 SG), the system leverages the natural physical properties of the materials to perform separation, reducing the need for supplementary separation methods and minimizing process complexity.
3Productivity
If plastics are recovered from waste streams with similar densities, then recycling can proceed, but the similar densities make complete separation difficult and economically viable recovery challenging
Solution Approach 1:
The recycling process is segmented into multiple gravity separation stages with progressively different specific gravity values. The first stage at 1.0 SG handles the lighter plastic fractions while the second stage at 1.15 SG handles the denser fractions. This segmentation enables the system to process plastics with similar densities through sequential separation, achieving complete recovery without requiring a single complex separation method.
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 method enhances the recovery of plastics by achieving precise separation and purification, increasing the economic viability of recycling processes and potentially recovering valuable materials like ABS and PS.
Implementation Method 1
separating material using gravity separation at about 1.0 SG into first lights and first sinks; and separating the first lights using gravity separation at about 1.15 SG into second lights and second sinks
Data Source
AI summary
Methods and systems presented herein are designed for processing waste material to extract plastics. These methods and systems encompass comminution and various stages of gravity separation. For comminution, a ball mill or a rod mill can be employed. The waste material can be or can include automobile shredder residue.