Core sands

Concrete block, 3 oval cores sand/gravel, 20 cm thick 1.0 ... 

Phenrez . [Hercules] Petroleum hydrocarbon thermoplasdc resin used in adhesives, coadngs, inks, medding compositions binders forfoundry core sand and fibrous prods. 

Dehydrated Sodium Silicate Bound Core Sand for Aluminum Casting... 

KIESEL AND VAN OENE Dehydrated Silicate Bound Core Sand... 

The final step in a core process is the destruction of the core within a solidified casting and the removal of used core sand. The time necessary to remove used core sand is called the shake-out time. The technique used for de-coring aluminum castings is to hit them with an impact hammer (13) ... 

To investigate formulation and process variables, the amount of core sand shaken out of a casting is monitored as a function of impact hammer exposure. Fig. 12 shows shake-out data for one silicate solid concentration and one cast metal to core sand weight ratio. The most obvious effect is that the more angular lake sand shakes out of castings faster than round grain sand. This was found true for all silicate ratios and silicate binder contents investigated. Low ratio silicates,... 

Core sand can be removed from cooled castings in 0 1 to 0 2 minutes using impact hammer techniques ... 

The total sand circuit flow and the need for new sand depends on the amoimt of cores (and core sand) used. Therefore, data on the sand circuit are very process-specific. Figure 4.27 gives data for a plant in the Netherlands. 

Internal re-use of core sand, therefore limiting the amount of material for disposal and the need for raw materials. 

The combined separation-regeneration technique can be apphed for the treatment of mixed green sand and chemically bonded sand. Regeneration is performed on the chemically-bonded sand flow and may include uncuied core sand. The technique may be applied in new and existing installations. 

A waste sand mix of green sand with chemically-bound core sand having the following characteristics 8 - 12 % fines content, 3 - 5 % LOI, <2 % humidity produces a regenerate with the following characteristics ... 

Furthermore, the technique may be applied for the regeneration of core sand of the COa-water glass type from aluminium foundries. This is discussed separately below. 

The higher recuperation rate (99%) is reached if only in-house core sand is regenerated. A rate of 95 % applies for mixed internal and external core sand... 

This technique has a lower performance than the thermal regeneration of organically bound sands. The following limitations occur lower immediate compressive strength shorter applicability times of the core sand mixtures stability loss upon storage of cores... 

Core production generates sand residues in the form of broken cores, cones with small mistakes and excess sand from the core-making machines. The excess sand can be hardened in a specific unit. Subsequently the various unused core sand flows are fed to a breaking unit. The resulting sand may be mixed with new sand for the production of new cores. 

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