Method for pelletizing carbon black reclaimed from waste tires

Abstract

One variation for a method for converting tires into pelletized, recovered carbon black includes: shredding a set of tires into a volume of tire rubber segments, the set of tires selected from a group comprising an agricultural tire, a commercial vehicle tire, and a passenger tire; in a pyrolytic reactor, thermally depolymerizing the volume of tire rubber segments into a volume of carbonaceous material; comminuting the volume of carbonaceous material; removing from the volume of carbonaceous material agglomerates larger than the maximum agglomerate diameter; within a mixer, mixing the volume of carbonaceous material with a binding agent over a first interval, the mixer inducing formation of a set of pellets of a range of pellet diameters; drying the set of pellets within a dryer to a particular moisture content; and removing from the set of pellets a first subset of pellets larger than a maximum pellet size.

We claim: 
     
         1 . A method for converting tires into pelletized, recovered carbon black comprising:
 splicing a set of tires into a volume of tire rubber segments comprising a set of virgin carbon black grades, a set of rubber polymers, and a set of rubber additives, the set of tires selected from a group comprising an agricultural tire, a commercial tire, and a passenger tire;   in a pyrolytic reactor, thermally depolymerizing the volume of tire rubber segments within an inert atmosphere into a set of pyrolytic byproducts comprising a volume of carbonaceous material comprising agglomerates of carbonaceous aggregates;   comminuting the volume of carbonaceous material to reduce a diameter of an agglomerate within the volume of carbonaceous material to less than a maximum agglomerate diameter;   removing from the volume of carbonaceous material agglomerates larger than the maximum agglomerate diameter and agglomerates smaller than a minimum agglomerate diameter;   within a mixer, mixing the volume of carbonaceous material with a binding agent over a first interval, the mixer inducing formation of a set of pellets of a range of pellet diameters;   drying the set of pellets within a dryer to a particular moisture content over a second interval defined by a rate the set of pellets translates across a length of the dryer and operating temperature of the dryer; and   removing from the set of pellets a first subset of pellets larger than a maximum pellet size.   
     
     
         2 . The method of  claim 1 , wherein splicing the set of tires comprises:
 within a primary tire shredder, separating tire rubber of the set of tires from a volume of steel wire and a volume of textile fiber; and,   within a secondary tire shredder proximal the primary tire shredder, shredding tire rubber of the set of tires into the volume of tire rubber segments comprising pieces of tire rubber of a desired surface area range configured to pyrolyze evenly into the volume of carbonaceous material, the volume of oil, and the volume of gas during thermal decomposition.   
     
     
         3 . The method of  claim 1 , wherein thermally depolymerizing the volume of tire rubber segments comprises thermally depolymerizing the volume of tire rubber segments into the volume of carbonaceous material comprising carbonaceous aggregates defining a matrix of organic materials derived from the set of virgin carbon black grades and inorganic materials derived from the set of rubber additives. 
     
     
         4 . The method of  claim 3 , further comprising selecting the set of tires from the group comprising the agricultural tire, the commercial tire, and the passenger tire according to a tire ratio corresponding to a threshold percentage of inorganic materials within the volume of carbonaceous material. 
     
     
         5 . The method of  claim 4 , wherein selecting the set of tires from the group comprising the agricultural tire, the commercial tire, and the passenger tire according to the tire ratio corresponding to the threshold percentage of sulfur by weight within the volume of carbonaceous material, the threshold percentage of sulfur less than twenty percent. 
     
     
         6 . The method of  claim 3 , wherein splicing the set of tires comprising splicing the set of tires into the volume of tire rubber segments comprising the set of rubber additives selected from the group comprising zinc oxide, silicon dioxide, and sulfur. 
     
     
         7 . The method of  claim 3 , further comprising washing the volume of carbonaceous material with an acid to release a portion of the set of rubber additives from the matrix. 
     
     
         8 . The method of  claim 1 , wherein drying the set of pellets within the dryer comprises drying the set of pellets to the particular moisture content less than two percent moisture content. 
     
     
         9 . The method of  claim 1 , further comprising:
 separating a set of high moisture content pellets exceeding the particular moisture content from the set of pellets;   milling the set of high moisture content pellets into a powder; and   within the mixer, mixing the powder with the volume of carbonaceous material.   
     
     
         10 . The method of  claim 1 , wherein removing the first subset of pellets larger than the maximum pellet size comprises removing the first subset of pellets larger than the maximum pellet size proportional to a maximum pellet hardness defined by a desired dispersion coefficient of the set of pellets when mixed a volume of rubber polymer. 
     
     
         11 . The method of  claim 1 , further comprising removing removing a second subset of pellets smaller than a minimum pellet size from the set of pellets, the minimum pellet size larger than a maximum particle size of the volume of carbonaceous material, the maximum particle size proportional to a particle size of a largest grade of carbon black in the set of a virgin carbon black grades. 
     
     
         12 . A method for converting tires into pelletized, recovered carbon black comprising:
 splicing a set of tires selected from a group comprising an agricultural tire, a commercial tire, and a passenger tire into a volume of tire rubber segments;   in a pyrolytic reactor, thermally depolymerizing the volume of tire rubber segments within an inert atmosphere into a set of pyrolytic byproducts comprising a volume of carbonaceous material comprising agglomerates of carbonaceous aggregates;   within a pelletizing system:   a. comminuting the volume of carbonaceous material to reduce a diameter of an agglomerate within the volume of carbonaceous material to less than a maximum agglomerate diameter;   b. within a mixer:
 i. spraying the volume of carbonaceous material with a binding agent; and 
 ii. mixing the volume of carbonaceous material over a first interval, the mixer inducing formation of a set of pellets of a range of pellet diameters, the first interval defined by a feed rate of a retort within the mixer and a length of the mixer; 
   c. drying the set of pellets within a dryer to a particular moisture content over a second interval defined by a rate the set of pellets translates across a length of the dryer and an operating temperature of the dryer, the rate the set of pellets translates across the length of the dryer defined by an angle between a plane of the length of the dryer and a horizontal plane;   d. removing from the set of pellets a first subset of pellets larger than a maximum pellet size.   
     
     
         13 . The method of  claim 12 , wherein drying the set of pellets within the dryer comprises heating the set of pellets to the operating temperature to induce evaporation of moisture within the set of pellets to less than two percent moisture content. 
     
     
         14 . The method of  claim 13 , further comprising:
 separating a subset of high moisture content pellets exceeding the particular moisture content from the set of pellets;   milling the set of high moisture content pellets into a powder; and   within the mixer, mixing the powder with the volume of carbonaceous material.   
     
     
         15 . The method of  claim 12 , wherein removing the first subset of pellets larger than the maximum pellet size comprises removing the first subset of pellets larger than the maximum pellet size proportional to a maximum pellet hardness defined by a desired dispersion coefficient of the set of pellets when mixed a volume of rubber polymer. 
     
     
         16 . The method of  claim 12 , further comprising removing removing a second subset of pellets smaller than a minimum pellet size from the set of pellets, the minimum pellet size larger than a maximum particle size of the volume of carbonaceous material, the maximum particle size proportional to a particle size of a largest grade of carbon black in the set of a virgin carbon black grades. 
     
     
         17 . The method of  claim 16 , wherein removing the set of pellets smaller than the minimum pellet size comprises removing the set of pellets smaller than the minimum pellet size larger than the maximum particle size of the volume of carbonaceous material proportional to the particle size of the largest grade of carbon black in the set of a virgin carbon black grades, the particle size of the largest grade of carbon black in the set of virgin carbon black grades exceeding 100 nanometers. 
     
     
         18 . The method of  claim 12 , wherein comminuting the volume of carbonaceous material comprising milling the volume of carbonaceous material within a hammer mill to a distribution of agglomerate sizes smaller than the maximum particle size of two micrometers and larger than the minimum particle size of 500 nanometers. 
     
     
         19 . The method of  claim 18 , further comprising:
 feeding agglomerates of recovered carbon larger than the maximum agglomerate size into the hammer mill; and   milling the agglomerates larger than the maximum agglomerate size over a third time interval to reduce agglomerate size of agglomerates larger than the maximum agglomerate size to smaller the maximum agglomerate size; and   mixing the powder into the volume of carbonaceous material.   
     
     
         20 . The method of  claim 19 , further comprising feeding the volume of carbonaceous material into a magnetic separator configured to extract remnants of the volume of steel from the volume of carbonaceous to reduce the inorganic content of the volume of carbonaceous. 
     
     
         21 . A system for converting tires into pelletized recovered carbon black comprising:
 a primary tire shredder configured to splice a set of tires into a volume of tire rubber segments, a volume of steel wire, and a volume of textile fiber, the set of tires selected from a group comprising an agricultural tire, a commercial tire, and a passenger tire;   a secondary tire shredder configured to splice the volume of tire rubber segments pieces of tire rubber of a desired surface area range configured to pyrolyze;   a pyrolytic reactor configured to thermally depolymerize the volume of tire rubber segments within an inert atmosphere into a set of pyrolytic byproducts comprising a volume of carbonaceous material comprising agglomerates of carbonaceous aggregates;   a mill configured to comminute the volume of carbonaceous material to a diameter of an agglomerate within the volume of carbonaceous material to less than a maximum agglomerate diameter;   a mixer configured to spray the volume of carbonaceous material with a binding agent, mix the volume of carbonaceous material and the binding agent and translate the volume of carbonaceous material across a length of the mixer, and form a set of pellets of a range of pellet diameters;   a dryer configured to dry the set of pellets within a dryer to a particular moisture content; and   a pellet classifier configured to remove from the set of pellets a subset of pellets:
 a. larger than a maximum pellet size proportional to a maximum pellet hardness defined by a desired dispersion coefficient of the set of pellets within a volume of rubber polymer; and 
 b. smaller than a minimum pellet size defined by a maximum particle size of the volume of carbonaceous material proportional to a particle size of a largest grade of carbon black in the set of a virgin carbon black grades within the volume of tire rubber segments. 
   
     
     
         22 . The system of  claim 21 , wherein the pyrolytic reactor comprising a continuous bed reactor comprising heating element interspersed along a length of the reactor and a conveying system configured to translate the volume to tire rubber over the heating elements to induce thermal decomposition of the volume of tire rubber segments incrementally along the length of the continuous bed reactor, at an outlet of the continuous bed reactor, the volume of tire rubber segments completely depolymerized into the volume of carbonaceous material.