Method to blend separator powders
| DWPI Title: Making a blended powder mixture useful in thermal battery separators involves adding a liquid selected from liquid nitrogen, methanol, ethanol or isopropanol, to a first and second powder where the first powder has specific angle of repose |
| Abstract: A method for making a blended powder mixture, whereby two or more powders are mixed in a container with a liquid selected from nitrogen or short-chain alcohols, where at least one of the powders has an angle of repose greater than approximately 50 degrees. The method is useful in preparing blended powders of Li halides and MgO for use in the preparation of thermal battery separators. |
| Use: For making a blended powder mixture (claimed) useful in making thermal battery separators. |
| Advantage: When using liquid nitrogen, the powders and the liquid can be mixed in a precooled metal container to avoid possible thermal-shock problems associated with glass containers. The container is precooled before use, such as with liquid nitrogen, to prevent rapid boiling that can cause sudden gas generation and overflow of powders from the container. The method is relatively inexpensive industrial Waring-type blenders can be used rather than using expensive dry blending equipment, such a V-blenders or multiaxis blenders. In comparison, it is noted that the angle of repose for the LiCl-KCl separator with 35% MgO was 62 degrees by previous Freon blending. The same material processed by liquid-nitrogen blending was 54 °, which is lower. This improves the flowability of the material for pelletizing operations. This is one situation where a liquid medium offers definite advantages. Liquid nitrogen has similar desirable properties of some halogenated hydrocarbons but without the negative environmental attributes. Liquid nitrogen is inexpensive and readily available and is compatible with the components in the separator mixes. It is readily removed at room temperature by evaporation and is not toxic to personnel. There are no problems of disposal or waste. The results demonstrate that using liquid nitrogen and isopropyl alcohol as the blending liquid in making the separator pellets is effective and provides similar quality of material as the separator pellets made with Freon. |
| Novelty: Making a blended powder mixture involves: adding in a container a liquid selected from liquid nitrogen, methanol, ethanol or isopropanol, to a first powder and a second powder, to form a mixture; mixing the mixture to form a homogeneous mixture; and removing the liquid to make a blended powder mixture. The first powder has an angle of repose greater than 50°. |
| Filed: 9/16/2002 |
| Application Number: US2002246609A |
| Tech ID: SD 6726.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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