Method for improvement of casting quality
Systems and methods for improved molding sand performance through use of recovered additives from the existing waste stream in a foundry. Sand, clay, and carbon-containing organic components are wet recovered from a green sand mold foundry dust recovery system. The sand and non-sand fractions may be further treated to reduce water content or adjust the levels of various components to generate a pre-mix additive for the generation of new green sand molds, that may display improved properties at ambient and high temperatures when compared to commonly employed traditional pre-mix. In some examples, pre-mixes having reduced sulfur content are obtained. In several embodiments, the non-sand fraction obtained from bag house dust or dust from mechanical reclamation includes increased levels of bentonite clay and carbon.
1. A method of forming a molding sand additive, comprising the steps of:
recovering a non-sand fraction from a green sand bag house dust recovery installation, wherein said non-sand fraction comprises a recovered clay component and a recovered carbon component;
recovering a sand fraction from the green sand bag house dust recovery installation;
reducing water content in said non-sand fraction; and
adjusting the relative levels of clay and carbon in said non-sand fraction.
2. The method of claim 1 , wherein said recovered clay component has a bentonite content between about 10% and about 85%.
3. The method of claim 1 , wherein said recovered carbon component as a loss on ignition content of about 3% to about 40%.
4. The method of claim 1 , wherein said reducing step achieves a water reduction of about 10% to about 95%.
5. The method of claim 1 , wherein said adjusting step comprises addition of clay.
6. The method of claim 5 , wherein said clay comprises bentonite.
7. The method of claim 6 , wherein said bentonite comprises a sodium bentonite.
8. The method of claim 1 , wherein said adjusting step comprises addition of organic compounds.
9. The method of claim 1 , wherein said adjusting step comprises addition of coal.
10. The method of claim 9 , wherein said coal comprises bituminous coal.
11. The method of claim 1 , wherein the non-sand fraction has a sulfur content of less than 0.03% by weight.