Abrasive Cleaning & Recycling
Abrasive Handling System
Most blast cleaning systems comprise of the following elements:
- The Abrasive elevator
- A device to move from the elevator and provide preliminary screening of the abrasive before it enters the separator - this may be by gravity or a screened rotary screw conveyor.
- An air wash abrasive separator to remove all dust, fines and contaminants from the abrasive.
- A hopper to collect refuse from the abrasive.
- A means of moving spent abrasive, sand and other contaminants to the elevator. This could be a helical screw, shaker conveyor or gravity.
Air Wash Separator
The role of the abrasive separator is to remove sand, scale, abrasive fines and other contaminants from the abrasive operating mix, so that only clean abrasive, properly-sized, is returned to the blast wheel for re-use. The degree of success of the separator in performing this operation in a large measure determines parts life, abrasive consumptions, the type of finish given the work piece and the speed and quality of cleaning.
A typical air wash separator is the gravity compensating flow separator commonly known as the CFS separator. The CFS separator is designed to utilise compensating flow to present a full length curtain or material to the air washing currents. This uniform low velocity curtain, permits a more thorough air washing of abrasive.
The screen (either rotary or fixed) removes any tramp metal from the abrasive. It also spreads out the abrasive across the length of the separator.
The baffle, when properly adjusted, permits a full width of abrasive to be presented to the air currents.
Operating Principal
Properly adjusted separator - Correct discard size
In other works, the greater the air speed in the separator, the larger particles eliminated (discard size) and vica versa.
The airflow speed is adjusted by controls on the suction pipes and it is the careful adjustment of this airflow, directed at the abrasive curtain, that carries away fines, contaminants and dust.
In practise, the following ratios should be used:
Application
Surface Preparation
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Quarter
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Discard Size
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Nominal Size
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De-sanding
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Third
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Descard Size
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Nominal Size |
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Shot Peening
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Half
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Discard Size
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Nominal Size |
NB: During de-sanding, the main enemy of wear part is sand.
A magnetic separator solves this problem efficiently.
Other Frequently Asked Questions