Types of abrasives
Abrasives are divided into two large families:
- Disposable abrasives
- Recoverable abrasives
This group includes low-cost abrasives that are normally not recovered for this reason or abrasives that, when used for the first time, are pulverised to the point that they are no longer reusable.
Abrasives such as silica sand, calcium carbonate, quartz, foundry waste are used on construction sites, outdoors, on all kinds of products (iron, steel, reinforced concrete, wood, etc.) to obtain, in addition to cleaning the substrate, a roughness that is normally necessary for better anchoring of the paints that will be applied later.
These types of abrasives are used with traditional free jet sandblasting machines which, if upgraded with the humidification kit, can eliminate the problem related to the dust generated by the sandblasting process through the injection of water into the air-abrasive mixture.
The abrasives that can be recovered and therefore used several times are as follows:
- angular and / or spherical metal grits
- brown or white aluminium oxide
- microspheres or glass grits
- ceramic microspheres
- vegetable abrasives such as corncob, walnut or hazelnut shells.
These abrasives are available in different grain sizes expressed in some cases in mesh and in other cases in microns according to the types or manufacturers.
Recoverable abrasives are usually much more expensive than non-disposable ones and are only convenient when they are reused.
The recycling of the abrasive implies the use of a system that removes and selects it so that when it is projected again on the surface to be treated, it has a similar effect and result every time.
Reusing a recoverable abrasive without carrying out a selection and dedusting of the same, means, each time, projecting an increasing amount of impurities, penalising the yield, increasing the amount of dust during sandblasting and getting to the need to completely eliminate the abrasive used by losing the advantages of recovery and less waste disposal which, in case of use of the sorting and dedusting system, is reduced to the exhausted abrasive and to what is eroded by the surface.