The present invention is drawn to a process for separating bentonite and carbon carrier particles from an air-dust mixture generated from a mechanical used-sand reclamation unit and, more particularly, a process as aforesaid wherein the bentonite and carbon carrier particles are recycled to a foundry sand preparation unit.
It is known in the prior art to reclaim used foundry sand by subjecting the used foundry sand to impact and shearing stresses in mechanical scouring units. See for example U.S. Pat. No. 3,312,403. During the mechanical scouring, the used sand granulars are separated from their outer shell (oolith shell) which comprises in part bentonite and carbon carrier materials. In the prior art this oolith shell is generally disposed of as unusable material. The reclaimed sand is then reused in the foundry operation operation.
The outer shell material also has value in that the bentonite and carbon carrier materials may be used again in sand preparation in the foundry. Accordingly, there have been some efforts in the prior art to separate the sand particles from the accompanying materials containing the bentonite and carbon carrier materials. These processes which employ a separation step do not result in a high recovery of the desirable bentonite and carbon carrier materials.
Naturally, it would be highly desirable to provide a process for treating the air dust mixture generated from mechanical used-sand reclamation units wherein a high degree of the usable bentonite and carbon carrier materials may be separated and recycled for foundry sand preparation.
Accordingly, it is the principle object of the present invention to provide an effect process for separating bentonite and carbon carrier particles from an air-dust mixture qenerated from a mechanical used-sand reclamation unit wherein a large portion of the desired bentonite and carbon carrier particles are separated for recycle to the foundry sand preparation unit.