Sludge processing

A method of drying a sludge having suspended and dissolved solids in a volatile liquid using a twin screw type rotary heat exchanger having a clearance between the twin screws, comprising:

• adding frangible scouring bodies to said sludge to create a mixture, said scouring bodies being larger than said clearance;
• flowing said mixture through said heat exchanger so as to evaporate at least some of said volatile liquid from said mixture and create a substantially dry particle product while said scouring bodies break and continuously remove said dry particle produce from the surface of said twin screws;
• and
• discharging said evaporated mixture of dry particle product and scouring bodies from said heat exchanger.

A method of drying a sludge having suspended and dissolved solids in a volatile liquid, comprising:

• adding scouring particles to said sludge to create a mixture, said scouring particles being of a size substantially larger than said suspended and dissolved solids;
• passing said mixture across a rotary conveyor type indirect heat exchanger having hollow flights so as to evaporate some of said volatile liquid from said mixture and create a substantially reduced volume product while said scouring particles continuously remove said reduced volume product from the surface of said flights;
• discharging said evaporated mixture of reduced volume product and scouring particles from said heat exchanger;
• separating said scouring particles from said reduced volume product;
• and
• recycling said separated scouring particles for use in said step of adding scouring particles to said sludge.

A method of drying a sludge having suspended and dissolved solids in a volatile liquid, comprising:

• adding scouring particles to said sludge to create a mixture, said scouring particles having a mean diameter substantially larger than the mean diameter of said suspended and dissolved solids;
• passing said mixture across a rotary conveyor type indirect heat exchanger having hollow flights so as to evaporate some of said volatile liquid from said mixture and create a substantially higher solids concentration product while said scouring particles continuously remove said higher solids concentration product from the surface of said flights;
• and
• discharging said evaporated mixture of a higher solids concentration product and scouring particles from said heat exchanger.

A method of drying a sludge having suspended and dissolved solids in a volatile liquid, comprising:

• adding scouring particles to said sludge to create a mixture, said scouring particles having a mean diameter substantially larger than the mean diameter of said suspended and dissolved solids;
• passing said mixture across a rotary screw type indirect heat exchanger having hollow flights so as to evaporate some of said volatile liquid from said mixture and create a substantially higher solids concentration product while said scouring particles continuously remove said higher solids concentration product from the surface of said flights;
• discharging said evaporated mixture of a higher solids concentration product and scouring particles from said heat exchanger;
• separating said scouring particles from said higher solids concentration product;
• and
• recycling said separating scouring particles for use in said step of adding scouring particles to said sludge.

A method of drying a sludge including suspended or dissolved solids in a volatile liquid to form a dry particulate product, said method comprising the steps of:

• adding scouring particles to said sludge to create a mixture, said scouring particles having a size larger than that of the particles comprising said particulate product;
• passing said mixture through a conveying type indirect heat exchanger having moving heat transfer surfaces so as to evaporate said volatile liquid from said mixture and create said particulate product while said scouring particles simultaneously remove caked particulate product from said heat transfer surfaces;
• discharging said mixture of particulate product and scouring particles from said heat exchanger;
• separating at least a portion of said scouring particles from said particulate product;
• and
• recycling said separated portion of said scouring particles for reuse in said step of adding scouring particles to said sludge.