Lightweight high-strength ceramsite and preparation method thereof

Abstract

A lightweight high-strength ceramsite, comprising solid raw materials and activator as the raw materials, which can be respectively expressed in parts by weight, the solid raw materials: 100 parts, the activator: 1-15 parts; wherein said solid raw materials comprise fly ash: 100 parts, high-alumina fly ash, bauxite and red mud: 6-18 parts, silica fume: 1-5 parts, surfactant: 0.1-3 parts, plasticizer: 6-24 parts; and said activator comprises alkali metal hydroxide: 5-20 parts and alkali metal silicate: 80-95 parts. The lightweight high-strength ceramsite product prepared has a density level of 700-1100 kg/m3 and cylindrical compressive strength of 10-20 MPa, and thus is not susceptible to damage.

Claims

1. A lightweight high-strength ceramsite, comprising solid raw materials and solid activator as raw materials, which can be respectively expressed in parts by weight, the solid raw materials:100 parts, the activator: 1-15 parts, characterized in that said solid raw materials comprise fly ash: 100 parts, high-alumina fly ash, bauxite and red mud: 6-18 parts, silica fume: 1-5 parts, surfactant: 0.1-3 parts, plasticizer: 6-24 parts; and said activator comprises alkali metal hydroxide: 5-20 parts and 60-95% by weight of alkali metal silicate solution: 80-95 parts.

2. The lightweight high-strength ceramsite according to claim 1, characterized in that said fly ash comprises the following components, loss on ignition: 2-10%, SiO.sub.2: 30%-70%, Al.sub.2O.sub.3:10%-50%, CaO: 1%-15%, Fe.sub.2O.sub.3: 1%-18%, MgO: 0.01%-8%, and TiO.sub.2: 0.01%-3%.

3. The lightweight high-strength ceramsite according to claim 1, characterized in that said plasticizer is one or more selected from the group consisting of Guangdong white clay, Guangdong black clay, kaolin, bentonite, PVA, and cellulose.

4. The lightweight high-strength ceramsite according to claim 1, characterized in that said high-alumina fly ash and bauxite comprise an alumina content of not less than 37%; and the weight ratio of red mud to high-alumina fly ash and bauxite is 1:2-5.

5. The lightweight high-strength ceramsite according to claim 1, characterized in that said solid raw materials further comprise iron ore tailings: 0.01-5 parts and calcite: 0.01-5 parts.

6. The lightweight high-strength ceramsite according to claim 1, characterized in that said alkali metal hydroxide is one or more selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide; and said alkali metal silicate in the alkali metal silicate solution is one or more selected from the group consisting of sodium silicate, potassium silicate and lithium silicate.

7. The lightweight high-strength ceramsite according to claim 1, characterized in that said surfactant is sodium lignosulfonate.

8. A method for preparing lightweight high-strength ceramsite, characterized in comprising the following steps: a. Weighing solid raw materials comprising fly ash: 100 parts, high-alumina fly ash, bauxite and red mud: 6-18 parts, silica fume: 1-5 parts, surfactant: 0.1-3 parts, plasticizer: 6-24 parts, and mixing the same, and preparing a solid activator: dissolving alkali metal hydroxide in an alkali metal silicate solution, after cooling to room temperature, stirring until a small amount of white precipitates are observed, pouring the resulting solution into a clean container; white crystals are formed at room temperature for 1-20 minutes into agglomerates, which are pulverized to form the solid activator; b. Mixing: mixing the solid raw materials and the solid activator thoroughly to form mixed materials; c. Pelletizing: pelletizing the mixed materials into particles; d. Curing: maintaining the particles under the conditions with a temperature of 70-100 C. and a humidity of 70-90% for 1-2 hours to be cured; e. Drying: drying the cured particles at a temperature of 100-300 C.; f. Sintering: subjecting the dried particles to a predetermined sintering process for 60-90 min; g. Forming finished product: cooling the sintered particles to room temperature to yield a lightweight high-strength ceramsite according to claim 1.

9. The method for preparing lightweight high-strength ceramsite according to claim 8, characterized in that the sintering process comprises specific steps of elevating the temperature from 100-300 C. at a rate of 20-40 C./min to 500-700 C., and subsequently further elevating the temperature to 1050-1350 C. at a rate of 5-25 C./min.

Description

MODE FOR CARRYING OUT THE INVENTION

(1) In order to illustrate the present invention in more detail, the following preparation examples are described. However, the scope of the present invention is not limited thereto.

Example 1

(2) Weighing solid materials: 850 g of fly ash, 20 g of Guangdong white clay, 100 g of high-alumina fly ash, 30 g of silica fume, and 8 g of sodium lignosulphonate; and these solid raw materials were mixed;

(3) Preparing an Activator:

(4) 5 g of sodium hydroxide and 40 g of 80% sodium water glass solution were weighed. Sodium hydroxide was added in the sodium water glass solution to be dissolved under stirring. After cooling to room temperature, stirring was continued until small amount of white precipitates were observed. The resulting solution was poured into a clean container; the white crystals were formed at room temperature for 1-20 minutes into agglomerates, which were pulverized to form a solid activator;

(5) Mixing: the solid raw materials and the solid activator were thoroughly mixed to form mixed materials;

(6) Pelletizing: the mixed materials were pelletized into particles;

(7) Curing: the particles were maintained under the conditions with a temperature of room temperature to 100 C. and a humidity of 70-90% for 1-2 hours to be cured;

(8) Drying: the cured particles were dried at a temperature of 120 C.;

(9) Sintering: the dried particles were sintered at a temperature of 1250 C. Specifically, the sintering process was carried out by the steps of elevating the temperature from 120 C. at a rate of 25 C./min to 600 C., and subsequently further elevating the temperature to 1250 C. at a rate of 15 C./min.

(10) Forming finished product: the sintered particles were cooled to room temperature to yield ceramsite as the finished product of Example 1.

Example 2

(11) Weighing solid materials: 880 g of fly ash, 40 g of bauxite, 10 g of sodium lignosulphonate, and 70 g of bentonite; and these solid raw materials were mixed;

(12) Preparing a Solid Activator:

(13) 15 g of potassium hydroxide and 87 g of 90% potassium water glass solution were weighed. Potassium hydroxide was added in the potassium water glass solution to be dissolved under stirring. After cooling to room temperature, stirring was continued until small amount of white precipitates were observed. The resulting solution was poured into a clean container; the white crystals were formed at room temperature for 1-20 minutes into agglomerates, which were pulverized to form a solid activator;

(14) Mixing: the solid raw materials and the solid activator were thoroughly mixed to form mixed materials;

(15) Pelletizing: the mixed materials were pelletized into particles;

(16) Curing: the particles were maintained under the conditions with a temperature of room temperature to 80 C. and a humidity of 70-90% for 1-2 hours to be cured;

(17) Drying: the cured particles were dried for 2 hours at a temperature of 100 C.;

(18) Sintering: the dried particles were sintered at a temperature of 1300 C. Specifically, the sintering process was carried out by the steps of elevating the temperature from 100 C. at a rate of 30 C./min to 700 C., and subsequently further elevating the temperature to 1300 C. at a rate of 10 C./min.

(19) Forming finished product: the sintered particles were cooled to room temperature to yield ceramsite as the finished product of Example 2.

Example 3

(20) Weighing solid materials: 860 g of fly ash, 40 g of silica fume, 50 g of bauxite, 20 g of cellulose, and 10 g of a surfactant; and these solid raw materials were mixed;

(21) Preparing a Solid Activator:

(22) 12 g of lithium hydroxide and 80 g of 92% lithium water glass solution were weighed. Lithium hydroxide was added in the lithium water glass solution to be dissolved under stirring. After cooling to room temperature, stirring was continued until small amount of white precipitates were observed. The resulting solution was poured into a clean container; the white crystals were formed at room temperature for 1-20 minutes into agglomerates, which were pulverized to form a solid activator;

(23) Mixing: the solid raw materials and the solid activator were thoroughly mixed to form mixed materials;

(24) Pelletizing: the mixed materials were pelletized into particles;

(25) Curing: the particles were maintained under certain temperature and humidity conditions for 1-2 hours to be cured;

(26) Temperature: room temperature to 80 C.;

(27) Humidity: 70-90%;

(28) Drying: the cured particles were dried for 2 hours at a temperature of 140 C.;

(29) Sintering: the dried particles were sintered at a temperature of 1200 C. Specifically, the sintering process was carried out by the steps of elevating the temperature from 140 C. at a rate of 40 C./min to 700 C., and subsequently further elevating the temperature to 1200 C. at a rate of 10 C./min.

(30) Forming finished product: the sintered particles were cooled to room temperature to yield ceramsite as the finished product of Example 3.

Example 4

(31) Weighing solid materials: 800 g of fly ash, 30 g of Guangdong white clay, 80 g of bentonite, 10 g of sodium lignosulphonate, and 50 g of high-alumina fly ash; and these solid raw materials were mixed;

(32) Preparing an Activator:

(33) 20 g of sodium hydroxide and 100 g of 75% sodium water glass solution were weighed. Sodium hydroxide was added in the sodium water glass solution to be dissolved under stirring. After cooling to room temperature, stirring was continued until small amount of white precipitates were observed. The resulting solution was poured into a clean container; the white crystals were formed at room temperature for 1-20 minutes into agglomerates, which were pulverized to form a solid activator;

(34) Mixing: the solid raw materials and the solid activator were thoroughly mixed to form mixed materials;

(35) Pelletizing: the mixed materials were pelletized into particles;

(36) Curing: the particles were maintained under certain temperature and humidity conditions for 1-2 hours to be cured;

(37) Temperature: room temperature to 90 C.;

(38) Humidity: 70-90%;

(39) Drying: the cured particles were dried for 2 hours at a temperature of 130 C.;

(40) Sintering: the dried particles were sintered at a temperature of 1250 C. Specifically, the sintering process was carried out by the steps of elevating the temperature from 130 C. at a rate of 30 C./min to 700 C., and subsequently further elevating the temperature to 1250 C. at a rate of 10 C./min.

(41) Forming finished product: the sintered particles were cooled to room temperature to yield ceramsite as the finished product of Example 4.

Example 5

(42) Weighing solid materials: 750 g of fly ash, 100 g of red mud, 10 g of silica fume, and 50 g of calcite; and these solid raw materials were mixed;

(43) Preparing an Activator:

(44) 15 g of sodium hydroxide and 80.5 g of 85% sodium water glass solution were weighed. Sodium hydroxide was added in the sodium water glass solution to be dissolved under stirring. After cooling to room temperature, stirring was continued until small amount of white precipitates were observed. The resulting solution was poured into a clean container; the white crystals were formed at room temperature for 1-20 minutes into agglomerates, which were pulverized to form a solid activator;

(45) Mixing: the solid raw materials and the solid activator were thoroughly mixed to form mixed materials;

(46) Pelletizing: the mixed materials were pelletized into particles;

(47) Curing: the particles were maintained under certain temperature and humidity conditions for 1-2 hours to be cured;

(48) Temperature: room temperature to 70 C.;

(49) Humidity: 70-90%;

(50) Drying: the cured particles were dried for 2 hours at a temperature of 150 C.;

(51) Sintering: the dried particles were sintered at a temperature of 1050 C. Specifically, the sintering process was carried out by the steps of elevating the temperature from 150 C. at a rate of 20 C./min to 700 C., and subsequently further elevating the temperature to 1050 C. at a rate of 10 C./min.

(52) Forming finished product: the sintered particles were cooled to room temperature to yield ceramsite as the finished product of Example 5.

Comparative Example 1

(53) Weighing solid materials: 850 g of fly ash, 20 g of Guangdong white clay, and 30 g of silica fume; and these solid raw materials were mixed;

(54) Preparing a Liquid Activator:

(55) 5 g of sodium hydroxide, 40 g of sodium water glass, and 5 g of water were weighed. Sodium hydroxide was added in the sodium water glass to be dissolved. The resulting solution was added with water and stirred to be homogenous, and then cooled to room temperature to yield a liquid activator.

(56) Mixing: the solid raw materials and the liquid activator were thoroughly mixed to form mixed materials;

(57) Pelletizing: the mixed materials were pelletized into particles;

(58) Curing: the particles were maintained under certain temperature and humidity conditions for 1-2 hours to be cured;

(59) Temperature: room temperature to 100 C.;

(60) Humidity: 70-90%;

(61) Drying: the cured particles were dried at a temperature of 120 C.;

(62) Sintering: the dried particles were temperature-programmed and elevated to 1250 C. and then sintered for 60 min.

(63) Forming finished product: the sintered particles were cooled to room temperature to yield ceramsite as the finished product of Comparative Example 1.

Comparative Example 2

(64) Weighing solid materials: 880 g of fly ash and 70 g of bentonite; and these solid raw materials were mixed;

(65) Preparing a Liquid Activator:

(66) 15 g of potassium hydroxide, 87 g of potassium water glass, and 8 g of water were weighed. Potassium hydroxide was added in the sodium water glass to be dissolved. The resulting solution was added with water and stirred to be homogenous, and then cooled to room temperature to yield a liquid activator.

(67) Mixing: the solid raw materials and the liquid activator were thoroughly mixed to form mixed materials;

(68) Pelletizing: the mixed materials were pelletized into particles;

(69) Curing: the particles were maintained under certain temperature and humidity conditions for 1-2 hours to be cured;

(70) Temperature: room temperature to 80 C.;

(71) Humidity: 70-90%;

(72) Drying: the cured particles were dried for 2 hours at a temperature of 100 C.;

(73) Sintering: the dried particles were sintered at a temperature of 1300 C. for 60 min.

(74) Forming finished product: the sintered particles were cooled to room temperature to yield ceramsite as the finished product of Comparative Example 2.

Comparative Example 3

(75) Weighing solid materials: 800 g of fly ash, 30 g of Guangdong white clay, 80 g of bentonite, 10 g of sodium lignosulfonate, and 50 g of high-alumina fly ash; these solid raw materials were mixed, and the resulting mixture was added with 8 g of water and stirred to be homogenous;

(76) Pelletizing: the solid raw materials added with water were pelletized into particles;

(77) Curing: the particles were maintained under certain temperature and humidity conditions for 1-2 hours to be cured;

(78) Temperature: room temperature to 90 C.;

(79) Humidity: 70-90%;

(80) Drying: the cured particles were dried for 2 hours at a temperature of 130 C.;

(81) Sintering: the dried particles were sintered at a temperature of 1250 C. for 80 min.

(82) Forming finished product: the sintered particles were cooled to room temperature to yield ceramsite as the finished product of Comparative Example 3.

Comparative Example 4

(83) Weighing solid materials: 750 g of fly ash, 100 g of red mud, 10 g of silica fume, and 50 g of calcite; these solid raw materials were mixed, and the resulting mixture was added with water and stirred to be homogenous;

(84) Pelletizing: the solid raw materials added with 12 g of water were pelletized into particles;

(85) Curing: the particles were maintained under certain temperature and humidity conditions for 1-2 hours to be cured;

(86) Temperature: room temperature to 70 C.;

(87) Humidity: 70-90%;

(88) Drying: the cured particles were dried for 2 hours at a temperature of 150 C.;

(89) Sintering: the dried particles were sintered at a temperature of 1050 C. for 90 min.

(90) Forming finished product: the sintered particles were cooled to room temperature to yield ceramsite as the finished product of Comparative Example 4.

(91) The ceramsites as the finished products obtained in Examples 1-5 and Comparative Examples 1-4 were tested. The results for the properties of the tested samples were shown below:

(92) TABLE-US-00001 Cylindrical Bulk density compressive strength Water absorption (kg/m.sup.3) (MPa) (%) Example 1 908 15.3 6.4 Example 2 894 13.5 8.6 Example 3 960 17.1 5.2 Example 4 1056 19.7 3.6 Example 5 720 11.6 9.3 Comp. Exp. 1 1020 15.6 5.6 Comp. Exp. 2 980 14.1 4.0 Comp. Exp. 3 850 7.2 9.1 Comp. Exp. 4 730 6.8 10.3

(93) The above data show that in the case where the bulk densities are close, Examples 1-5 of the present invention, in which a solid activator is used, have equivalent or even better properties regarding the cylindrical compressive strength and water absorption as compared with Comparative Examples 1-2, in which a liquid activator is used; and Examples 1-5 of the present invention have significantly better properties than Comparative Examples 3-4, in which no activator is used.

(94) The foregoing illustrations merely represent the preferred embodiments of the present invention, while the protection scope of the present invention is not limited thereto. Any modifications or replacements within the technical scope disclosed by the present invention that could be easily envisaged by persons skilled in the art should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be defined by the protection scope of the claims.