A feeder assembly configured to transport cryogenic blast media from a source of cryogenic blast media into a flow of transport gas, the cryogenic blast media comprising a plurality of particles, each particle of the plurality of particles having a respective initial size, the feeder assembly comprising: a. a metering element; b. a feeding rotor rotatable about a feeding rotor axis, wherein the feeding rotor comprises i. a circumferential surface, and ii. a plurality of pockets disposed in the circumferential surface, each of the plurality of pockets having a respective circumferential pocket width; c. a comminutor disposed between the metering element and the feeding rotor; d. a guide disposed between the comminutor and the feeding rotor, the guide configured to receive particles from the comminutor and guide the particles into the plurality of pockets as the feeding rotor rotates, the guide comprising a wiping edge disposed adjacent the circumferential surface, wherein the wiping edge is oriented generally parallel to the feeding rotor axis, wherein the wiping edge is configured to force particles into the plurality of pockets as the feeding rotor rotates; and d. a transport gas flow path through which the transport gas flows during operation of the feeder assembly, wherein the metering element is configured to: i. receive from a first region the cryogenic blast media from the source of cryogenic blast media; ii. control the rate of flow of the cryogenic blast media through the feeder assembly; and iii. discharge the cryogenic blast media to the comminutor; and wherein the comminutor is: i. configured to receive cryogenic blast media from the metering element; ii. configured to reduce the size of a plurality of the plurality of particles from each particle's respective initial size to a second size which is smaller than a predetermined size; and iii. disposed to discharge the cryogenic blast media directly to the feeding rotor through the guide, and wherein the feeding rotor is: i. disposed to receive the cryogenic blast media directly from the comminutor through the guide; and ii. configured to introduce the cryogenic blast media into the flow of transport gas in the transport gas flow path. a. a metering element; b. a feeding rotor rotatable about a feeding rotor axis, wherein the feeding rotor comprises i. a circumferential surface, and ii. a plurality of pockets disposed in the circumferential surface, each of the plurality of pockets having a respective circumferential pocket width; i. a circumferential surface, and ii. a plurality of pockets disposed in the circumferential surface, each of the plurality of pockets having a respective circumferential pocket width; c. a comminutor disposed between the metering element and the feeding rotor; d. a guide disposed between the comminutor and the feeding rotor, the guide configured to receive particles from the comminutor and guide the particles into the plurality of pockets as the feeding rotor rotates, the guide comprising a wiping edge disposed adjacent the circumferential surface, wherein the wiping edge is oriented generally parallel to the feeding rotor axis, wherein the wiping edge is configured to force particles into the plurality of pockets as the feeding rotor rotates; and d. a transport gas flow path through which the transport gas flows during operation of the feeder assembly, wherein the metering element is configured to: i. receive from a first region the cryogenic blast media from the source of cryogenic blast media; ii. control the rate of flow of the cryogenic blast media through the feeder assembly; and iii. discharge the cryogenic blast media to the comminutor; and i. receive from a first region the cryogenic blast media from the source of cryogenic blast media; ii. control the rate of flow of the cryogenic blast media through the feeder assembly; and iii. discharge the cryogenic blast media to the comminutor; and wherein the comminutor is: i. configured to receive cryogenic blast media from the metering element; ii. configured to reduce the size of a plurality of the plurality of particles from each particle's respective initial size to a second size which is smaller than a predetermined size; and iii. disposed to discharge the cryogenic blast media directly to the feeding rotor through the guide, and i. configured to receive cryogenic blast media from the metering element; ii. configured to reduce the size of a plurality of the plurality of particles from each particle's respective initial size to a second size which is smaller than a predetermined size; and iii. disposed to discharge the cryogenic blast media directly to the feeding rotor through the guide, and wherein the feeding rotor is: i. disposed to receive the cryogenic blast media directly from the comminutor through the guide; and ii. configured to introduce the cryogenic blast media into the flow of transport gas in the transport gas flow path. i. disposed to receive the cryogenic blast media directly from the comminutor through the guide; and ii. configured to introduce the cryogenic blast media into the flow of transport gas in the transport gas flow path.