Ceramic particles for use in a solar power tower
Ceramic particles for use in a solar power tower and methods for making and using the ceramic particles are disclosed. The ceramic particle can include a sintered ceramic material formed from a mixture of a raw material and MnO. The sintered ceramic material can include about 0.01 wt % to about 10 wt % MnO, about 0.1 wt % to about 20 wt % Fe 2 O 3 , and about 0.01 wt % to about 10 wt % Mn 2 O 3 . The ceramic particle can have a size from about 8 mesh to about 170 mesh.
1. A ceramic particle for use in a solar power tower, comprising:
a ceramic material formed from a mixture comprising a raw material and MnO, wherein the raw material comprises kaolin or bauxite or a mixture thereof, and wherein the ceramic material further comprises:
about 0.01 wt % to about 10 wt % MnO,
about 0.1 wt % to about 20 wt % Fe 2 O 3 , and
about 0.01 wt % to about 10 wt % Mn 2 O 3 ; and
wherein the ceramic particle has a size of about 8 mesh to about 170 mesh.
2. The ceramic particle of claim 1 , wherein the mixture further comprises about 0.01 wt % to about 20 wt % FeO.
3. The ceramic particle of claim 1 , wherein the ceramic material further comprises about 0.1 wt % to about 20 wt % FeO.
4. The ceramic particle of claim 1 , wherein the ceramic particle has a density of at least about 1.5 g/cc.
5. The ceramic particle of claim 1 , wherein the ceramic particle has a surface roughness of less than 5 μm.
6. The ceramic particle of claim 1 , wherein the ceramic particle has a spherical shape.
7. The ceramic particle of claim 5 , wherein exposure of the ceramic particle to solar heat energy in the solar power tower reduces a Munsell Value of the ceramic particle by at least about 0.1.
8. The ceramic particle of claim 1 , wherein the mixture is formed into green pellets that are calcined to provide the ceramic material.
9. The ceramic particle of claim 1 , wherein the mixture is formed into green pellets that are dried and then sintered to provide the ceramic material.
10. A solar power tower comprising the ceramic particle of claim 1 .
11. A method of manufacturing ceramic particles for use in a solar power tower, comprising:
introducing a raw material and manganese oxide to a mixer, the raw material comprising about 0.1 wt % to about 50 wt % silica and about 30 wt % to about 99 wt % alumina;
stirring the raw material and manganese oxide to form a dry homogeneous particulate mixture having an average particle size of less than about 15 microns;
introducing water to the mixer to contact the dry homogeneous particulate mixture;
stirring the dry homogeneous particulate mixture with the water to cause formation of green pellets;
removing the green pellets from the mixer;
drying the green pellets to provide dried pellets; and
sintering the dried pellets to provide a plurality of ceramic particles, wherein the sintering oxidizes a first portion of the manganese oxide from MnO to Mn 2 O 3 .
12. The method of claim 11 , wherein the raw material comprises alumina, kaolin, or bauxite or mixtures thereof.
13. The method of claim 11 , further comprising subjecting the ceramic particles to solar heat energy in the solar power tower to oxidize a second portion of the manganese oxide from MnO to Mn 2 O 3 .
14. The method of claim 11 , wherein the plurality of ceramic particles has a Munsell value of at least 6 prior to exposure to solar heat energy in a solar power tower.
15. The method of claim 14 , wherein the plurality of ceramic particles has a Munsell value of less than 6 after exposure to the solar heat energy in the solar power tower.
16. The method of claim 11 , wherein sintering comprises subjecting the dried pellets to a temperature between about 1,250° C. to about 1,550° C. for about 4 minutes to about 20 minutes.
17. A method of manufacturing ceramic particles for use in a solar power tower, comprising:
introducing a raw material and manganese oxide to a mixer;
introducing about 0.01 wt % to about 20 wt % FeO to the mixer;
stirring the raw material, manganese oxide, and FeO to form a dry homogeneous particulate mixture having an average particle size of less than about 15 microns;
introducing water to the mixer to contact the dry homogeneous particulate mixture;
stirring the dry homogeneous particulate mixture with the water to cause formation of green pellets;
removing the green pellets from the mixer;
drying the green pellets to provide dried pellets; and
sintering the dried pellets to provide a plurality of ceramic particles, wherein the sintering oxidizes a first portion of the manganese oxide from MnO to Mn 2 O 3 .
18. The method of claim 17 , wherein the sintering oxidizes a first portion of the iron oxide from FeO to Fe 2 O 3 .
19. The method of claim 18 , wherein a second portion of the iron oxide is oxidized from FeO to Fe 2 O 3 upon subjecting the ceramic particles to solar heat energy in a solar power tower.