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US 7,093,781 B2Granted
Process and apparatus for manufacturing powder rubber
AssigneeLehigh Technologies, Inc.
InventorsGeorge W. Meckert, Peter J. Waznys, Anthony M. Cialone
Life of this patent
Estimating the term…
Abstract
A process and apparatus for making crumb and powder rubber from preprocessed rubber particles. The process and apparatus provides an energy efficient operation wherein the preprocessed rubber particles are dried, precooled, frozen, comminuted and sized using a closed cryogenic fluid cycle.
Claims23
A process of making powder rubber comprising the steps of
- (a) drying preprocessed rubber particles;
- (b) precooling said dried rubber particles with an inert gas at a temperature not higher than about 0° F.;
- (c) freezing said rubber particles to a temperature below the glass transition temperature by contacting said particles with a cryogenic liquid;
- (d) comminuting said cooled rubber particles to a size in the range of crumb or powder rubber;
- (e) heating said cold comminuted rubber particles to ambient temperature;
- and
- (f) screening said comminuted rubber particles into desired powder rubber size ranges.
4 more elements
A process for making powder rubber comprising the steps of:
- (a) drying preprocessed rubber particles having a particle size in the range of between about −⅜ inch and about +40 mesh;
- (b) precooling said dried rubber particles with a coolant nitrogen gas recycle stream at a temperature in the range of between about 0° F. and about −200° F.;
- (c) freezing said precooled rubber particles to below the glass transition temperature of said rubber by contact and exposure to liquid nitrogen wherein said liquid nitrogen is heated to gaseous nitrogen;
- (d) comminuting said rubber particles below the glass transition temperature in the presence of said gaseous nitrogen, and a coolant nitrogen gas recycle system;
- (e) recycling said nitrogen gas, generated in said freezing step (c), to said precooling step (b) and said comminuting step (d);
- (f) warming said comminuting rubber particles to ambient temperature;
- and
- (g) screening said ambient temperature comminuted rubber particles into desired powder rubber size ranges.
5 more elements
An apparatus for making powder rubber comprising:
- (a) drying means for drying a feedstock of preprocessed rubber particles;
- (b) precooling means for precooling said dried rubber particles with inert gas at a temperature no higher than about 0° F.
- (c) freezing means for cooling said precooled rubber particles to a temperature below the glass transition temperature;
- (d) comminuting means for comminuting said rubber particles below the glass transition temperature to a size in the range of powder rubber;
- (e) warming means for warming said comminuted rubber particles to ambient temperature;
- and
- (f) screening means for providing said comminuting rubber particles in fine powder rubber size ranges.
4 more elements
An apparatus for making powder rubber comprising:
- (a) drying means for drying a feedstock of rubber particles in a size range of about −⅜ inch and about +40 mesh;
- (b) precooling means for precooling said dried feedstock with a coolant inert gas recycle stream at a temperature in the range of between about 0° F. and about −20° F.;
- (c) freezing means for cooling said precooled feedstock to a temperature below the gas transition temperature of said rubber particles by contact and exposure to liquid nitrogen;
- (d) comminuting means for comminuting said cooled feedstock to a particle size no greater than about −80 mesh in the presence of a coolant at a temperature in the range of about −90° F. and about −125° F.;
- (e) recycling means for recycling said gaseous nitrogen, vaporized from said liquid nitrogen in said freezing means, from said comminuting means back into said precooling means and said comminuting means;
- (f) warming said comminuted feedstock exiting said comminuting means;
- and
- (g) screening said comminuted feedstock into desired powder rubber size ranges.
5 more elements
Dependencies are inferred from the claim text.