1. A process for preparing hollow ceramic or metal microspheres, comprising the steps of: forming ceramic or metal slurry, comprising ceramic or metal powders, water and dispersant and having a certain solid phase content, into a stable foam slurry by using a foaming agent; introducing the stable foam slurry into a centrifugal atomization equipment to atomize it into hollow slurry droplets, while being sprayed into a molding chamber; drying rapidly to form hollow microsphere green body; collecting the hollow microsphere green body and sintering.
2. The process as claimed in claim 1, wherein the ceramic or metal powder is selected from oxide ceramic, non-oxide ceramic, solid waste materials such as coal gangue, fly ash, tailings, sludge, waste stones, and metalalloy materials.
3. The process as claimed in claim 1, wherein, in the ceramic or metal slurry having a certain solid phase content, the volume of said powders is 5-60% of the total volume of the solution after the addition of said powders; the dispersant is 0.1-3% of the total volume; the foaming agent is 0.1-1% of the total volume, and balance being water.
4. The process as claimed in claim 1, wherein said dispersant is selected from commonly-used dispersants, particularly ammonium citrate, ammonium polymethacrylate, tetramethylethylene diamine, calgon and others; said foaming agent is selected from commonly-used foaming agents, particularly triton, propyl gallate and others.
5. The process as claimed in claim 1, wherein ceramic or metal slurry having certain solid phase contend is prepared by mixing the ceramic or metal powders with water and dispersant and ball-milling; the foaming agent is added to the ceramic or metal slurry having a certain solid content followed by stirring sufficiently to prepare the slurry into a stable foam slurry.
6. The process as claimed in claim 1, wherein the stable foam slurry has a slurry foaming rate of between 20% and 600% and a diameter of air bubble of between 0.001 mm and 1.5 mm, and is substantially without apparent antifoaming or foam joining phenomenon for 1-10 days shelf time
7. A device for preparing hollow ceramic or metal microspheres, comprising a centrifugal atomization equipment, a molding chamber, an exhaust gas system, a separation system, and a hot-blast air system providing hot-blast air for molding chamber;
wherein the centrifugal atomization equipment is located at upper part, with its lower part being connected with the molding chamber, an exhaust gas system is connected to the upper part of the molding chamber, a separation system is arranged below the molding chamber, the molding chamber is connected with the hot-blast air system.
8. The device according to claim 7, wherein the foam slurry is atomized into hollow slurry droplets by said centrifugal atomization equipment.
9. The device according to claim 7, wherein the temperature in the molding chamber is 80-500\xb0 C.
10. A hollow microsphere, wherein said microsphere has a diameter of 0.001-1.5 mm, such as 1-100 microns, or 500-1500 microns, and contains ceramic or metal components other than silicates, such as high temperature (heat-resistant) ceramics and high temperature (heat-resistant) metalsalloys selected from non-oxide systems, particularly selected from the group consisting of ZrO2, Si3N4, WC and SiC.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A device for regulating a fluid flow through a drain, comprising:
first and second downwardly-sloping, gravity flow valves configured to each be biased in a closed position;
first and second downwardly-sloping valve seats; and
wherein a first end portion of the first valve is seated beneath the first valve seat when the first valve is in a closed position, and wherein a second end portion of the second valve is seated beneath the second valve seat when the second valve is in a closed position.
2. The device of claim 1, wherein at least one of the first and second valves comprises a tapered valve having a circular horizontal cross-section.
3. The device of claim 2, wherein each of the first and second valves comprises a tapered valve having a circular horizontal cross-section.
4. The device of claim 3, wherein each of the first and second valves comprises inner and outer portions, and wherein the outer portion has an average thickness that is less than 90% of an average thickness of the inner portion.
5. The device of claim 1, wherein a bottom surface of at least one of the first and second valves comprises ribs configured to strengthen the valve.
6. The device of claim 1, further comprising a stem coupled to the first and second valves, and wherein the stem is disposed through a central portion of each of the first and second valves.
7. The device of claim 1, wherein at least one of the first and second valves is biased to be convex in an upstream direction.
8. The device of claim 1, wherein the first valve has a first outer 5 mm edge interval having a first average thickness, and the second valve has a second outer 5 mm edge interval having a second average thickness, and wherein the first average thickness is less than 95% of the second average thickness.
9. The device of claim 8, wherein the first average thickness is less than 90% of the second average thickness.
10. The device of claim 1, further comprising a housing that includes the first and second valve seats, and wherein each of the first and second valves is disposed within the housing.
11. The device of claim 1, wherein the first and second valves are separated by no more than three inches.
12. The device of claim 1, further comprising a stem coupled to each of the first and second valves.
13. The device of claim 12, wherein the stem further comprises first and second bumps, and wherein the first and second valves are coupled to stem such that a portion of the first valve is configured to rest upon the first bump, and a portion of the second valve is configured to rest upon the second bump.
14. The device of claim 12, wherein the stem further comprises first and second recessed portions, and wherein the first and second valves are disposed in the first and second recessed portions, respectively.
15. The device of claim 1, further comprising an ultraviolet light emitter.
16. A cartridge configured to be inserted into a urinal that includes the device of claim 1.
17. A urinal that includes the device of claim 1.
18. A floor drain that includes the device of claim 1.