Resource recovery system for high moisture content grinding waste sludge

Abstract

A resource recovery system for high-moisture-content grinding waste sludge involves first mechanically dewatering the high-moisture-content waste sludge; then mixing a two-dimensional dielectric loss enhancer into the dewatered wet waste sludge to form a premixed waste sludge; feeding the premixed waste sludge into a microwave resonant cavity of a microwave reactor via a non-metallic screw conveyor; and sequentially performing rapid heating, isothermal dewatering, and drying steps through gradient microwave power to form dry waste sludge material; finally, applying high-power microwaves to the dry waste sludge material for in-situ catalysis and heavy metal solidification resource recovery steps to form functional powder material.

Claims

1. A resource recovery system for high-moisture-content grinding waste sludge, the system comprising: a microwave reactor, wherein a microwave resonant cavity of the microwave reactor is divided into a rapid heating zone, a constant-temperature dehydration zone, a drying zone, and a resource recovery zone according to the conveying path of a premixed waste sludge, each zone providing microwave power at different gradients; and a non-metallic spiral conveying mechanism, wherein a spiral conveying shaft of the non-metallic spiral conveying mechanism is disposed inside the microwave resonant cavity for dynamically rotating and conveying the premixed waste sludge sequentially through each zone.

2. The resource utilization system for high moisture content grinding waste sludge as described in claim 1, wherein, The screw conveyor shaft is made of alumina or silicon nitride.

3. The resource utilization system for high moisture content grinding waste sludge as described in claim 1, wherein, The microwave reactor has a microwave frequency of 2.45 GHz, a microwave power density of 2.0 kW / kg in the rapid heating zone, a microwave power density of 1.2 kW / kg in the constant temperature dehydration zone, a microwave power density of 0.5 kW / kg in the drying zone, and a microwave power density of 2.5 kW / kg in the resource recovery zone.

4. The resource utilization system for high moisture content grinding waste sludge as described in claim 3, wherein, The rotational speed of the screw conveyor shaft is set to a range of 5 to 15 RPM.

5. The resource recovery system for high moisture content grinding waste sludge as described in claim 1 further includes a dehumidification unit connected to the microwave resonant cavity for discharging water vapor from the microwave resonant cavity.

6. The resource utilization system for high moisture content grinding waste sludge as described in claim 5 further includes an auxiliary hot air unit connected to the microwave resonant cavity for introducing an auxiliary drying airflow into the microwave resonant cavity.

7. The resource utilization system for high moisture content grinding waste sludge as described in claim 6 further includes a gas-liquid separation unit connected to the dehumidification unit, which separates the extracted water vapor into water and gas, and the separated water is collected in a collection cylinder and then discharged.

8. The resource utilization system for high moisture content grinding waste sludge as described in claim 7 further includes an activated carbon filtration unit connected to the gas-liquid separation unit, wherein the separated gas is discharged after passing through the activated carbon filtration unit.

9. The resource utilization system for high moisture content grinding waste sludge as described in claim 7 further includes an air heater connected to the gas-liquid separation unit, wherein the separated gas passes through the air heater to become the auxiliary drying airflow and is incorporated into the auxiliary hot air unit.

10. The resource utilization system for high moisture content grinding waste sludge as described in claim 1 further includes a porous conveyor belt disposed below the screw conveyor shaft for receiving the premixed waste sludge fed by a feed hopper, conveying the premixed waste sludge into the microwave resonant cavity, and for being conveyed by the screw conveyor shaft through rotation.

11. The resource recovery system for high-moisture-content grinding waste sludge as described in claim 1, wherein, The premixed waste sludge includes a wet waste sludge with a moisture content between 70% and 80% and a two-dimensional dielectric loss enhancer mixed into the wet waste sludge.

12. The resource recovery system for high-moisture-content grinding waste sludge as described in claim 11, wherein, The two-dimensional dielectric loss enhancer accounts for 1.0 wt% to 4.0 wt% of the total weight of the wet sludge.

13. The resource recovery system for high-moisture-content grinding waste sludge as described in claim 12, wherein, The two-dimensional dielectric loss enhancer comprises reduced graphene oxide (rGO) and transition metal carbonitride (MXene); the weight ratio of reduced graphene oxide (rGO) to transition metal carbonitride (MXene) is 2:1.

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