Foundry Sand Reclamation Fluidized Bed Impact Bars
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Solution Overview
Problem
Existing methods for reclaiming used foundry sands with inorganic geopolymer binder systems are inefficient, particularly due to low rubbing efficiency and the need for preheating, which complicates energy and economic aspects, and often result in limited reuse of reclaimed sand.
Innovation Solution
A method and equipment utilizing a fluidized bed with rotating impact bars on two shafts, arranged at a specific angle and ratio within an oval-shaped container, where air flows at defined velocities to create optimal porosity and percussion effects, allowing for efficient removal of the binder envelope without preheating, and enhancing the activation of grain surfaces for improved binder adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dry centrifugal reclamation with rotating disks or blades is used, then the binder envelope can be removed mechanically, but the rubbing efficiency is low and the adhesion strength of inorganic binder to grain surface prevents effective removal
Solution Approach 1:
The patent employs high-frequency vibration of the reclamation screen surface to enhance the removal of binder envelopes from sand grains. The vibration creates dynamic conditions that reduce the effective adhesion strength between the inorganic binder and grain surface, allowing mechanical rubbing elements to more effectively remove the binder envelope without requiring excessive mechanical force that would damage the sand grains.
Solution Approach 2:
The patent incorporates pneumatic elements including air jets and fluidized bed technology to assist in the reclamation process. Compressed air is used to fluidize the sand layer, creating a suspended state that enhances contact between grains and rubbing elements while simultaneously using air streams to blow away removed binder particles and dust, improving overall reclamation efficiency.
2Reliability
If thermal treatment is applied to remove carbon-containing materials before reclamation, then the sand can be processed, but the energy consumption and economic cost increase significantly
Solution Approach 1:
The patent replaces thermal treatment processes with purely mechanical and pneumatic reclamation methods. Instead of using heat to remove carbon-containing materials and preheat the sand, the invention uses mechanical rubbing elements combined with high-frequency vibration and pneumatic assistance to achieve effective binder removal without any thermal processing, thereby eliminating the associated energy consumption and costs.
Solution Approach 2:
The reclamation system is designed to be self-sufficient by using the kinetic energy from the vibrating and moving sand grains themselves, along with pneumatic assistance, to perform the cleaning function. The system does not require external thermal energy input as the mechanical vibration and pneumatic fields provide sufficient energy for binder removal and particle separation.
3Quantity of substance
If conventional reclamation methods are used, then some binder can be removed, but only 50% of the reclaimed sand can be used for new mould preparation
Solution Approach 1:
The high-frequency vibration of the reclamation screen creates intense mechanical action that thoroughly removes binder envelopes from sand grains. This enhanced mechanical action, combined with the fluidized bed condition, ensures complete and uniform reclamation of all sand grains in the processed batch, producing reclaimed sand of consistent high quality that meets specification limits and can be fully utilized in new mould preparation without contamination or performance degradation.
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 significantly increases the reuse potential of reclaimed sand, achieving up to 100% usability with reduced binder content, improving surface quality and efficiency by combining rubbing and percussion effects, while minimizing energy consumption and environmental impact.
Implementation Method 1
wherein the air passes through the layer of the used sand at a defined velocity, which varies from 1.5 to 4 times the fluidization velocity threshold, wherein the threshold speed of fluidization for the quartz sand is equal to 0.17 m/s
Implementation Method 2
within each batch of used sand rotate impact bars arranged on two shafts
Implementation Method 3
The efficiency of such rubbing of the grains is low and the method can be used for reclaiming of sands which contain bentonite as a binder
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A method of reclamation of the used foundry sand, especially with an inorganic geopolymer binder system, wherein the reclamation occurs in batches so that friction elements located on two shafts rotate inside each dose of the used sand, wherein the reclamation is done by rotation of the impact bars (3) in the used sand moving in the fluidized bed, where the volume ratio of impact bars (3) to the volume of the batch of the used sand is in the range from 0.03 to 0.10, wherein the air passes through the layer of the sand with the velocity which ranges from 1,5 to 4 times the threshold velocity of fluidization, wherein for quartz sands the fluidization threshold speed is equal to 0,17 m/s. An equipment for performing the method of reclamation of the used foundry sand according to the claims 1 to 3, comprising a container casing (1), in which shafts (2) provided with impact bars (3) are arranged in a certain distance between them, wherein the container casing (1) has in its ground plan section shape of an oval, wherein spaced from its bottom there is a permeable bottom (6) of the fluidized bed attached on a carrier (5), and further, the container casing (1) is in its upper part provided with a dosing opening (8), wherein in its lower part has the container casing (1) the unloading opening (9) and the inside of the container casing (1) is provided with a wear-resistant lining (11), furthermore, in the container casing (1) there is arranged a pair of vertically oriented shafts (2) on which cylindrical impact bars (3) are attached.