Bentonite modifier, modified bentonite, and use thereof

Abstract

The present disclosure relates to a bentonite modifier, comprising a water-soluble thiosulfate, a water-soluble alcohol compound, and a water-soluble amine compound, wherein the amounts of thiosulfate, the alcohol compound, and the amine compound are in the ratio of (0.31):(0.31):(0.31). The present disclosure further relates to a bentonite-containing cement additive capable of resisting permeation and salt corrosion, comprising bentonite and said modifier, wherein the content of the bentonite modifier is 0.25% of the bentonite by weight. Meanwhile, the present disclosure also provides use of the modified bentonite.

Claims

1. A cement additive capable of resisting permeation and salt corrosion, consisting of a modified bentonite and a bentonite texturizer, wherein the modified bentonite consists of bentonite and a bentonite modifier, wherein, the bentonite modifier consists of a water-soluble thiosulfate, a water-soluble alcohol compound, and a water-soluble amine compound, wherein the mass ratio of the thiosulfate to the alcohol compound to the amine compound is (0.31):(0.31):(0.31), and the content of the bentonite modifier is 0.25% of the bentonite by weight, the bentonite has a crystalline structure, the bentonite texturizer is a mixture of active silica powder and a water reducer, and the amounts of the modified bentonite, the active silica powder, and the water reducer by weight are in the ratio of 100:(330):(0.33.5).

2. The additive of claim 1, wherein said active silica powder is at least one of fine powder with 80 m screen residue 12% manufactured from a silicon industrial waste residue, an amorphous SiO.sub.2 powder, and a natural SiO.sub.2 mineral.

3. The additive of claim 1, wherein said water reducer is at least one selected from the group consisting of naphthalene-based water reducers, melamine sulfonate-based water reducers, polycarboxylate-based water reducers, sulfamate-based water reducers, and modified lignosulfonate-based water reducers.

4. A cement capable of resisting permeation and salt corrosion, comprising cement clinker, and the cement additive capable of resisting permeation and salt corrosion according to claim 1, wherein the content of said cement additive accounts for 4% to 20% of the total weight of the cement.

5. The cement capable of resisting permeation and salt corrosion of claim 4, wherein the content of said cement additive accounts for 5% to 15% of the total weight of the cement.

6. The additive of claim 2, wherein said amorphous SiO.sub.2 powder is white carbon black, and said natural SiO.sub.2 mineral is silica stone or diatomite.

7. The additive of claim 1, wherein the water-soluble thiosulfate is at least one selected from the group consisting of lithium thiosulfate, sodium thiosulfate, and potassium thiosulfate.

8. The additive of claim 1, wherein the water-soluble alcohol compound is at least one selected from the group consisting of polyol, polyvinyl alcohol, and polyethylene glycol.

9. The additive of claim 1, wherein the water-soluble amine compound is at least one selected from the group consisting of triethanolamine, isopropanol amine, hydrazine hydrate, water-soluble alkylamines, and alkenamides.

10. The additive of claim 8, wherein said polyol is ethylene glycol and/or isopropanol, and said polyethylene glycol is at least one selected from the group consisting of polyethylene glycol 200 (PEG 200), polyethylene glycol 400 (PEG 400), and polyethylene glycol 600 (PEG 600).

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The present disclosure will be described in detail in combination with examples, but the scope of the present disclosure is not limited to the following examples.

(2) Various materials used in the examples of the present disclosure are commercially available.

(3) Various performance indexes of the bentonite-containing concrete of the present disclosure were tested according to the provisions as set forth in Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete (GBT50082-2009).

Example 1

(4) A bentonite modifier was prepared by homogeneously mixing lithium thiosulfate, ethylene glycol, triethanolamine, and water in the mass ratio of 1:1:1:1.

(5) The bentonite modifier was mixed with bentonite to obtain a modified bentonite, wherein the adding amount of the bentonite modifier was 0.4% on a dry weight basis of the bentonite.

Example 2

(6) A bentonite modifier was prepared by homogeneously mixing sodium thiosulfate, ethylene glycol, isopropanolamine, and water in the mass ratio of 0.85:1:1:1.2.

(7) When milling a block granular bentonite, the obtained bentonite modifier was continuously and uniformly added into the bentonite. The resulting mixture was then ground by a mill to obtain a modified bentonite, wherein the adding amount of the bentonite modifier was 1.5% on a dry weight basis of the bentonite.

(8) The modified bentonite was added into a 32.5-grade cement powder, followed by homogenization, wherein the adding amount of the modified bentonite was 7% by weight of the cement. The compressive strength of the cement was improved by 5 Mpa in 3 or 28 days. When the cement was used in the construction of a biogas plant, there was no indication of leakage or salt corrosion.

Example 3

(9) A bentonite modifier was prepared by homogeneously mixing potassium thiosulfate, ethylene glycol, isopropanolamine, triethanolamine, and water in the mass ratio of 1:1:0.5:0.3:1.

(10) The obtained bentonite modifier was added into a bentonite powder and stirred homogeneously, wherein the adding amount of the bentonite modifier was 1% by weight of the bentonite powder. After 8 hours of aging, a modified bentonite which can be used in cement and concrete was obtained.

(11) The modified bentonite was added into a 42.5-grade cement powder, followed by homogenizing, wherein the adding amount of the modified bentonite was 10% by weight of the cement. The 3-day compressive strength of the cement was improved by 5 Mpa, and the 28-day compressive strength thereof was improved by 5 Mpa. When the cement was used in the construction of a kitchenware cleaning pool, after two years of observation, there was no indication of leakage or salt corrosion.

Example 4

(12) A bentonite modifier was prepared by homogeneously mixing lithium thiosulfate, ethylene glycol, poval, triethanolamine, and water in the mass ratio of 1:0.5:0.2:0.8:1.5.

(13) During purification of bentonite, the obtained modifier was added into a bentonite suspension and fully stirred, followed by aging for 2 h, wherein the adding amount of the modifier was 0.4% on a dry weight basis of the bentonite. The resulting mixture was then dried and milled according to a conventional process, to obtain a modified bentonite which can be used in cement and concrete.

(14) The modified bentonite was added into a 32.5-grade cement powder, followed by homogenization, wherein the adding amount of the modified bentonite was 8% on a dry weight basis of the cement. The 3-day compressive strength of the cement was improved by 4 Mpa, and the 28-day compressive strength was improved by 4 Mpa. When the cement was used in the construction of a manure pit, after two years of observation, there was no indication of leakage or salt corrosion.

Example 5

(15) A bentonite modifier was prepared by mixing lithium thiosulfate, ethylene glycol, triethanolamine, a double chain quaternary ammonium salt, and water in the mass ratio of 1:1:0.85:0.15:1.2 into a solution.

(16) The obtained bentonite modifier was added into a bentonite powder and stirred homogeneously, wherein the adding amount of the bentonite modifier was 3% on a dry weight basis of the bentonite powder. After 8 hours of aging, a modified bentonite which can be used in cement and concrete was obtained.

(17) The modified bentonite was added into a 32.5-grade cement powder, followed by homogenization, wherein the adding amount of the modified bentonite was 7% by weight of the cement. The compressive strength of the cement was improved by 7 Mpa in 3 days, and the 28-day compressive strength thereof was improved by 8.1 Mpa. When the cement was used in the construction of sewer lines, after two years of observation, there was no indication of leakage or salt corrosion.

Example 6

(18) The modified bentonite of Example 2, a water reducer, and silica stone were blended in the mass ratio of 100:0.3:25, and then ground into a fine powder with fineness <12%, thus obtaining a bentonite-containing cement and concrete additive capable of resisting permeation and salt corrosion.

(19) The above bentonite-containing additive was added into 52.5-grade cement, followed by homogenizing. The adding amount was 3% by weight of the cement. When the resulting cement was used in the construction of coastal dikes, after two years of observation, there was no indication of leakage or salt corrosion.

Example 7

(20) The modified bentonite powder of Example 3 (with a fineness of 80 m screen residue <12%, and a montmorillonite content of 91%), industrial by-product silicon powder (known as white carbon black), and a powdered melamine-based water reducer in the mass ratio of 100:10:0.8 were blended and then homogenized, to obtain a bentonite-containing concrete additive capable of resisting permeation and salt corrosion.

(21) This additive, in replacement of 5% of slag powder was added into a clinker powder, and blended to form 42.5-grade cement, which was used for the construction of culverts. Over two years of observation, no indication of leakage or salt corrosion had been found.

Example 8

(22) The modified bentonite of Example 4, an aminosulfonic-based water reducer and diatomite concentrate as the texturizer, a commercially available ZC-R.sub.1-type bentonite composite modifier as the bentonite modifier were added in the mass ratio of 100:30:1.2 into a mill to be ground into powder. In the grinding process, the ZC-R.sub.1-type bentonite modifier was continuously added as instructed, to prepare a finished powder with a fineness of 80 m screen residue <12%, i.e. a bentonite-containing concrete additive capable of resisting permeation and salt corrosion.

(23) This additive was added into cement during the mixing process of the cement. The adding amount of this additive was 6% by weight of the cement. The cement was used in the construction of a sewage pool. After two years of observation, no indication of leakage or salt corrosion has been found.

Example 9

(24) The modified bentonite of Example 5, silica fume, and powdered modified lignosulfonate water reducer used as raw materials were mixed together in the mass ratio of 100:11.8:3.2, followed by homogenization, to prepare a finished powder, i.e. a bentonite-containing concrete additive capable of resisting permeation and salt corrosion.

(25) This additive was added in a cement in the course of blending mortar used for bathroom. The adding amount was 5% by weight of the cement. When the cement was used in the construction of a sewage pool, after two years of observation, no indication of permeation or salt corrosion was found.

Example 10

(26) This example employed 42.5-grade cement in a cement plant mainly used in residential and water conservancy constructions, wherein cement blending materials included slag, coal ash, limestone in a ratio of 1:1:1. The average of the total amount of blending materials was 28% of the cement, the fineness of finished cement being 80 m screen residue 3%.

(27) Block granular sodium-based bentonite was used, wherein the average content of montmorillonite was tested to be 86%.

(28) Silica fume as the active silica, and a naphthalene based water reducer were used. Both were ordinary products commercially available. The modified bentonite of Example 1, the silica fume, and the naphthalene based water reducer were blended uniformly in a mass ratio of 100:5:1.6, to obtain a bentonite-containing cement additive capable of resisting permeation and salt corrosion.

(29) Preparation of the cement capable of resisting permeation and salt corrosion of this example was as follows.

(30) Modified bentonite was crushed into a modified bentonite powder with 80 m screen residue <12%, and then blended into finely ground clinker powder with the silica fume, the water reducer, and slag powder in proportion, followed by homogenizing, to obtain the bentonite-containing cement capable of resisting permeation and salt corrosion. The total weight of the bentonite and the texturizer was 5% by weight of the cement product, and the adding amount of original slag powder was reduced by 5%. The obtained cement capable of resisting permeation and salt corrosion was used for preparing concrete.

(31) The performance of the concrete capable of resisting permeation and salt corrosion of this example was tested in the following way.

(32) The anti-permeability level of the concrete produced in this Example was tested to be S12. The trial produced 5000 tons of bentonite-containing cement capable of resisting permeation and salt corrosion was used in tunnel engineering without adding a swelling agent. Over three years of observation, no indication of leakage or salt corrosion was found.

(33) The cement product of this example had a standard consistency of 22.1%, an average initial setting time of 151 minutes, an average final setting time of 213 minutes, an average three-day compressive strength of 29.9 MP, an average three-day rupture strength of 3.1 MPa, an average 28-day compressive strength of 50.8 MPa, and an average 28-day rupture strength of 5.1 MPa.

Comparative Example 1

(34) Concrete was produced by blending the cement of Example 10 with a swelling agent. In the same testing condition, obvious damage caused by leakage and salt corrosion appeared. During the construction of tunnel engineering, a swelling agent which was 12% by weight of the cement as anti-permeability agent was blended to the cement. However, due to the permeation of water in the geologic environment, sulfate corrosion was still very serious.

(35) The originally used ordinary cement of 42.5 grade had a standard consistency of 22.8%, an average initial setting time of 162 minutes, an average final setting time of 215 minutes, an average three-day compressive strength of 25.8 MPa, an average three-day rupture strength of 2.8 MPa, an average 28-day compressive strength of 48.4 MPa, and an average 28-day rupture strength of 4.8 MPa.

(36) From the results of Example 10 and Comparative Example 1, it can be seen that, compared with Comparative Example 1, the effects of resisting permeation and salt corrosion of the bentonite-containing cement concrete capable of resisting permeation and salt corrosion in Example 10 was more satisfactory. With respect to mechanical properties, the product of Example 10 had an average three-day compressive strength improved by 4 MPa and an average 28-day compressive strength improved by 2.4 MPa compared with the product of Comparative Example 1.

Example 11

(37) The raw materials used in the experiment were as follows.

(38) A 42.5-grade cement in a dry process rotary kiln of a cement plant was used, wherein the production process of the cement was as follows. Clinker and blending materials were ground to be clinker powder and slag powder respectively. The clinker powder and slag powder were blended into ordinary 42.5-grade cement to be supplied to tunnel engineering. The blending amounts of slag powder and clinker powder were 30% and 70% of the cement, respectively. The blending materials comprising mineral waste residue, coal cinder, plus 5% of gypsum were ground to be the slag powder.

(39) The modified bentonite of Example 2, commercially available pipe ash silica fume, and melamine powder water reducer were used.

(40) In this example, the mass ratio of the modified bentonite to silica fume to the water reducer was 100:5:0.9.

(41) The preparation of the cement capable of resisting permeation and salt corrosion of this example was as follows. The modified bentonite of Example 2 was firstly crushed into bentonite powder with 80 m screen residue <12%, and then blended into finely ground clinker powder with the silica fume, the water reducer, and slag powder in proportion, followed by homogenizing, to obtain the bentonite-containing cement capable of resisting permeation and salt corrosion. The total weight of the bentonite and the texturizer was 5% by weight of the cement product, and the adding amount of original slag powder was reduced by 5%. The obtained cement capable of resisting permeation and salt corrosion was used for preparing concrete.

(42) The performance of the concrete capable of resisting permeation and salt corrosion was tested in the following way.

(43) The anti-permeability level of the concrete produced in this example was tested to be S12. The trial produced 5000 tons of bentonite-containing cement capable of resisting permeation and salt corrosion was used in tunnel engineering without adding a swelling agent. Over three years of observation, there was no indication of leakage, salt corrosion, or sugaring.

(44) The cement product of this example had a standard consistency of 22.3%, an average initial setting time of 153 minutes, an average final setting time of 215 minutes, an average three-day compressive strength of 30.1 MPa, an average three-day rupture strength of 3.1 MPa, an average 28-day compressive strength of 51.8 MPa, and an average 28-day rupture strength of 5.2 MPa.

Comparative Example 2

(45) Concrete was produced by blending the cement of Example 11 with a swelling agent. In the same testing condition, obvious damage caused by leakage and salt corrosion appeared. During the construction of tunnel engineering, a swelling agent which was 12% by weight of the cement as waterproof anti-permeability agent was blended to the cement. However, due to severe permeation of water in the geologic environment, sulfate corrosion was still very serious, and a lot of sugaring appeared.

(46) The cement product of this comparative example had a standard consistency of 22.9%, an average initial setting time of 165 minutes, an average final setting time of 217 minutes, an average three-day compressive strength of 25.3 MPa, an average three-day rupture strength of 2.8 MPa, an average 28-day compressive strength of 48.1 MPa, and an average 28-day rupture strength of 4.8 MPa.

(47) Analysis of Measurement Results:

(48) From the results of Example 11 and Comparative Example 2, it can be seen that, compared with Comparative Example 2, the bentonite-containing cement and concrete capable of resisting permeation and salt corrosion of the Example 11 had more satisfactory effects of resisting permeation and salt corrosion. As for the mechanical properties, compared with Comparative Example 2, the product of Example 11 had a three-day compressive strength increased by 4.8 MPa and a 28-day compressive strength increased by 3.7 MPa.

Example 12

Raw Materials for Experiment

(49) A special 42.5-grade cement from a cement plant producing low-aluminum dam clinker was used. The cement was mainly used for coastal burrock engineering and wave cone block. The cement blending materials comprised mineral waste residue and coal ash in a ratio of 1:1, and accounted for 30% the amount of the cement in average. The finished cement had a fineness of 80 m screen residue 5%.

(50) The modified bentonite of Example 3, diatomite concentrate, and a naphthalene based water reducer commercially available were used.

(51) In this example, the adding amounts of the modified bentonite, the texturizer diatomite, and the naphthalene based water reducer were in a ratio of 100:28:1.5.

(52) Preparation of the cement capable of resisting permeation and salt corrosion of this example was as follows.

(53) The total adding amount of the bentonite and the bentonite texturizer (i.e. diatomite and water reducer) was 8% by weight of the total cement. Meanwhile, the amount of slag was reduced by 8%. The existing technique was adopted to blend and mill the materials to produce the cement capable of resisting permeation and salt-corrosion. The power consumption for milling per ton of cement was reduced by 5 KW.Math.h, and the cost of per ton of cement was substantially kept unchanged. 5000 tons of bentonite-containing cement capable of resisting permeation and salt-corrosion was trial produced by using the method of the present disclosure. The obtained bentonite-containing cement capable of resisting permeation and salt-corrosion was used to produce concrete.

(54) The performance of the concrete capable of resisting permeation and salt corrosion was tested in the following way.

(55) The anti-permeability level of the concrete produced in this example was tested to be S10. The trial produced 5000 tons of cement was used for coastal burrock engineering. During blending of the concrete, no silica fume or calcium sulfate-based swelling agent was added. No obvious indication of stripping caused by seawater corrosion was found over 3 years of observation, and thus the effects of resisting permeation and salt corrosion were rather satisfactory.

(56) The bentonite-containing cement capable of resisting permeation and salt corrosion had a standard consistency of 22.2%, an average initial setting time of 183 minutes, an average final setting time of 249 minutes, an average three-day compressive strength of 23.9 MPa, an average three-day rupture strength of 2.5 MPa, an average 28-day compressive strength of 48.9 MPa, and an average 28-day rupture strength of 4.8 MPa.

Comparative Example 3

(57) The cement of Example 12 was used. According to the provisions of the GBT50082-2009, the concrete impervious grade was S4. In coast burrock engineering, special cement of 42.5 grade plus silica fume, water reducer, and calcium sulfate swelling agent were used to blend concrete. However, the stripping of burrock concrete caused by salt corrosion was still very serious, and maintenance costs thereof were high.

(58) The cement product of this comparative example had a standard consistency of 22.1%, an average initial setting time of 176 minutes, an average final setting time of 248 minutes, an average three-day compressive strength of 20.8 MPa, an average three-day rupture strength of 2.3 MPa, an average 28-day compressive strength of 46.3 MPa, and an average 28-day rupture strength of 4.5 MPa.

(59) Analysis of Measurement Results:

(60) From the results of Example 12 and Comparative Example 3 it can be seen that, compared with Comparative Example 3, the product of Example 12 had great improvement on the effects of resisting permeation and salt corrosion. As for the mechanical properties, the three-day compressive strength and 28-day compressive strength of the product of Example 12 compared with that of Comparative Example 3 had been respectively improved by 3.1 MPa and 2.6 MPa.

Example 13

Materials for Experiments

(61) A 42.5-grade cement was used, which was produced by grinding clinker and blending materials to clinker powder and slag powder respectively, and blending the resulting clinker powder and the slag powder. The blending materials that were ground to the slag powder were formed by mineral waste residue, coal ash, and 3% of anhydrite. The cost of the slag powder was 183 RMB/t. The amounts of clinker powder and slag powder used accounted for 28% and 72% of the 42.5-grade cement, respectively.

(62) The modified bentonite of Example 4, silica fume, and a naphthalene-based water reducer commercially available were used.

(63) In this example, the mass ratio of the modified bentonite to the silica fume to the water reducer was 100:12:3.

(64) Preparation of the cement capable of resisting permeation and salt corrosion of this example was as follows.

(65) According to the existing technique of cement production, during the blending of the finished product, the components resisting permeation and salt corrosion were pre-mixed and then added to fine-grained cement powder, followed by homogenizing, to prepare the bentonite-containing cement capable of resisting permeation and salt corrosion, wherein the adding amount of the components was 7% by weight of the total cement. Meanwhile, the original amount of the slag powder was reduced by 7%. 5000 tons bentonite-containing cement capable of resisting permeation and salt corrosion was produced. The obtained bentonite-containing cement capable of resisting permeation and salt-corrosion was used to produce concrete.

(66) The performance of the bentonite-containing concrete capable of resisting permeation and salt-corrosion of this example was tested in the following way.

(67) The anti-permeability level of the concrete produced in this example was tested to be S12. The trial produced 5000 tons of bentonite-containing cement capable of resisting permeation and salt corrosion was used in subway engineering without adding a swelling agent. The trial engineering sections indicated no leakage or salt corrosion over 2 years of observation.

(68) The obtained bentonite-containing cement capable of resisting permeation and salt corrosion had a standard consistency of 22.3%, an average initial setting time of 151 minutes, an average final setting time of 213 minutes, an average three-day compressive strength of 31.9 MPa, an average three-day rupture strength of 3.3 MPa, an average 28-day compressive strength of 50.8 MPa, and an average 28-day rupture strength of 5.1 MPa.

Comparative Example 4

(69) The original cement of Example 13 was used, to which a sulfate swelling agent as the waterproof agent accounting for 10% by weight of the cement was added during the construction of subway engineering. However, as the salt corrosion at the sections which can be permeated by surface water was very serious, the maintenance thereof was rather troublesome.

(70) The original cement had a standard consistency of 22.5%, an average initial setting time of 147 minutes, an average final setting time of 215 minutes, an average three-day compressive strength of 26.3 MPa, an average three-day rupture strength of 2.8 MPa, an average 28-day compressive strength of 48.6 MPa, and an average 28-day rupture strength of 4.8 MPa.

(71) Analysis of Measurement Results:

(72) From the results of Example 13 and Comparative Example 4 it can be known that, compared with Comparative Example 4, the product of Example 13 had significantly improved effects of resisting permeation and salt corrosion, achieving prefect effects. As to mechanical properties, the average 3-day compressive strength was improved by 5.6 MPa, and the average 28-day compressive strength was improved by 2.2 MPa.

Example 14

(73) Raw materials used in this Example:

(74) Cement: 42.5-grade cement, commercially available.

(75) The modified bentonite of Example 5, silica fume, and a modified lignosulfonate water reducer commercially available were used.

(76) In this example, the mass ratio of the modified bentonite to the silica fume to the water reducer was 100:20:3.

(77) The cement capable of resisting permeation and salt corrosion of this example was prepared in the following way. The total amount of the bentonite and texturizer was 15% by weight of the total cement. During the blending of concrete, the bentonite powder, silica fume, and water reducer were measured and added, respectively.

(78) The concrete capable of resisting permeation and salt corrosion which was produced by blending fully met the requirements of sewage treatment projects. No indication of leakage or salt corrosion was found over 3 years of observation, and thus the effects of resisting permeation and salt corrosion were satisfactory. The sugaring of the concrete had been significantly improved such that the phenomenon of sugaring did not appear substantially.

Example 15

(79) In a 3.548 m dry process rotary kiln production line, the average daily output of clinker was 1750 t/d, and the average output per machine hour was 72.9 t/h. The waste gas that was collected by the kiln system passed through a humidifier tower, and then was dedusted by an electric dust collector. The total amount of the ash recycled by the humidifier tower and the electric dust collector was about 8.1 tons per hour, approximately accounting for 7% by weight of the total amount of raw materials that were fed into the kiln. The dust-collection of the raw material mill system employed a bag-type dust collector, and the recycled ash amount obtained by dedusting of the raw materials was about 6.7 tons. In the prior art, the recycled ash of the kiln system was fed together with the recycled ash of the raw materials via a raw material powder chute into a raw material homogenizing silo. The kiln condition was merely slightly influenced after the raw material powders were finely adjusted. In the case that the recycled ash of the kiln system was fed directly via a raw material elevator into the kiln when the raw material mill stopped, the kiln condition fluctuated violently, and thus the yield and quality were influenced a lot, frequently generating calcined clinker which was crusted and thickly granulated. The blending materials of 32.5-grade cement were mineral waste residue, coal cinder, and limestone, and the total amount of the blending materials accounted for 48% by weight of the cement. The granular blending materials were blended with clinker, gypsum at the grinding head and were fed into a cement mill for grinding. The finished 32.5-grade cement had an average initial setting time of 125 minutes, an average final setting time of 187 minutes, an average standard consistency of 24.1%, an average 3-day compressive strength of 17.6 MPa, an average 3-day rupture strength of 1.9 MPa, an average 28-day compressive strength of 36.6 MPa, and an average 28-day rupture strength of 3.7 MPa. When the cement was used, there was no slurrying, but sugaring or a large number of craquelure appeared.

(80) The method of the present disclosure was used, wherein the recycled ash of the raw material mill was still fed into the raw material homogenizing silo, and the modified bentonite of Example 1 at an amount equal to 6% by weight of the recycled ash of the kiln system was continuously and evenly added to the recycled ash of the kiln system during the convey process and then fed into a steel silo near the cement mill as substituted blending slag powder. During blending in the cement mill, the total amount of blending materials was reduced from 48% to 43%, and the recycled ash modified by the bentonite powder at an amount equivalent to 5% by weight of the finished cement was continuously added into the ground powder from the cement mill, i.e. the amounts of clinker minerals and the blending materials in the finished cement powder were kept substantially equivalent to those of the original 32.5-grade cement, respectively. The cement blended with the recycled ash modified by the modified bentonite had an average initial setting time of 120 minutes, an average final setting time of 181 minutes, an average standard consistency of 24.2%, an average 3-day compressive strength of 20.7 MPa, an average 3-day rupture strength of 2.2 MPa, an average 28-day compressive strength of 37 Mpa, and an average 28-day rupture strength of 3.7 MPa, i.e. the average 3-day compressive strength was improved by 3 MPa, and the average 28-day strength was substantially unchanged. The construction or workability of said cement was improved, and substantially no sugaring or craquelure appeared.

Example 16

(81) In a 3.347 m dry process rotary kiln production line, the average daily output of clinker was 1500 t/d, and the average output per machine hour was 62.5 t/h. The waste gas that was collected by the kiln system passed through a humidifier tower, and then was dedusted by an electric dust collector. The total amount of the recycled ash recycled by the humidifier tower and the electric dust collector was about 7 tons per hour, approximately accounting for 7% by weight of the total amount of raw materials that were fed into the kiln. The dust-collection of the raw material mill system employed a bag-type dust collector, and the recycled ash amount obtained by dedusting of the raw materials was about 6 tons. In the prior art, the recycled ash of the kiln system was fed together with the recycled ash of the raw materials via a raw material powder chute into a raw material homogenizing silo. The kiln condition was only lightly influenced after the raw material powders were finely adjusted. In the case that the recycled ash of the kiln system was fed directly via a raw material elevator into the kiln when the raw material mill stopped, the kiln condition fluctuated violently, and thus the yield and quality were influenced a lot, frequently generating calcined clinker which was crusted and thickly granulated. The blending materials of 32.5-grade cement were mineral waste residue, coal cinder, and coal ash, and accounted for 46% by weight of the cement. The granular blending materials were blended with clinker and gypsum at the grinding head and fed into a cement mill for grinding. The finished 32.5-grade cement had an average initial setting time of 136 minutes, an average final setting time of 201 minutes, an average standard consistency of 24.3%, an average 3-day compressive strength of 17.1 MPa, an average 3-day rupture strength of 1.9 MPa, an average 28-day compressive strength of 37.3 MPa, and an average 28-day rupture strength of 3.7 MPa. When the cement was used, there was no slurrying, but sugaring and a large number of craquelure appeared.

(82) The method of the present disclosure was used, wherein the recycled ash of the raw material mill was still fed into the raw material homogenizing silo, and the modified bentonite of Example 2 at an amount equal to 7% by weight of the recycled ash of the kiln system was continuously and evenly added to the recycled ash of the kiln system during the convey process and then fed into a steel silo near the cement mill as substituted blending slag powder. During blending in the cement mill, the total amount of blending materials was reduced from 46% to 41%, and the recycled ash modified by the bentonite powder at an amount equivalent to 5% by weight of the finished cement was continuously added into the ground powder from the cement mill, i.e. the amounts of clinker minerals and the blending materials in the finished cement powder were kept substantially unchanged from those of the original 32.5-grade cement. The cement blended with the recycled ash modified by the modified bentonite had an average initial setting time of 126 minutes, an average final setting time of 191 minutes, an average standard consistency of 24.2%, an average 3-day compressive strength of 20.5 MPa, an average 3-day rupture strength of 2.2 MPa, an average 28-day compressive strength of 37.8 Mpa, and an average 28-day rupture strength of 3.9 MPa, i.e. the average 3-day compressive strength was improved by 3 MPa, and the 28-day strength was substantially unchanged. The construction or workability of said cement was improved, and substantially no sugaring or craquelure appeared.

Example 17

(83) In a 345 m dry process rotary kiln production line, the average daily output of clinker was 1200 t/d, and the average output per machine hour was 50 t/h. The waste gas that was collected by the kiln system passed through a humidifier tower, and then was dedusted by an electric dust collector. The total amount of the ash recycled by the humidifier tower and the electric dust collector was about 5.9 tons per hour, approximately accounting for 7.5% by weight of the total amount of raw materials that were fed into the kiln. The dust-collection of the raw material mill system employed a bag-type dust collector, and the recycled ash amount obtained by dedusting of the raw materials was about 5 tons. In the prior art, the recycled ash of the kiln system was fed together with the recycled ash of the raw materials via a raw material powder chute into a raw material homogenizing silo. The kiln condition was merely slightly influenced after the raw material powders were finely adjusted. In the case that the recycled ash of the kiln system was fed directly via a raw material elevator into the kiln when the raw material mill stopped, the kiln condition fluctuated violently, and thus the yield and quality were influenced a lot, frequently generating calcined clinker which was crusted and thickly granulated. The blending materials of 32.5-grade cement were mineral waste residue, burned gangue, and limestone, and accounted for 45% by weight of the cement. The granular blending materials were blended with clinker and gypsum at the grinding head and fed into the cement mill for grinding. The finished 32.5-grade cement had an average initial setting time of 137 minutes, an average final setting time of 196 minutes, an average standard consistency of 23.4%, an average 3-day compressive strength of 18.5 MPa, an average 3-day rupture strength of 1.9 MPa, an average 28-day compressive strength of 38.6 MPa, and an average 28-day rupture strength of 3.8 MPa. When the cement was used, there was no slurrying, but sugaring and a large number of craquelure appeared.

(84) The method of the present disclosure was used, wherein the recycled ash of the raw material mill was still fed into the raw material homogenizing silo, and the recycled ash of the kiln system as well as the modified bentonite of Example 3 was fed into a steel silo near the cement mill. As substituted blending slag, the adding amount of the recycled ash was 6% by weight of the finished cement, and the adding amount of the modified bentonite was 0.6% by weight of the finished cement. During blending in the cement mill, the total amount of blending materials was reduced from 45% to 38.4%, and the recycled ash modified by the bentonite powder at an amount equivalent to 6.6% by weight of the finished cement was continuously added into the ground powder from the cement mill, i.e. the amounts of clinker minerals and the blending materials in the finished cement powder were kept substantially unchanged from those of the original 32.5-grade cement, respectively. The cement blended with the recycled ash modified by the modified bentonite had an average initial setting time of 125 minutes, an average final setting time of 183 minutes, an average standard consistency of 23.8%, an average 3-day compressive strength of 20.9 MPa, an average 3-day rupture strength of 2.2 MPa, an average 28-day compressive strength of 38.5 Mpa, and an average 28-day rupture strength of 3.8 MPa, i.e. the average 3-day compressive strength was improved by 2.4 MPa, and 28-day strength kept substantially unchanged. The construction or workability of said cement was improved, and substantially no sugaring or craquelure appeared.

Example 18

(85) In a 4.364 m dry process rotary kiln production line, the average daily output of clinker was 3250 t/d, and the average output per machine hour was 135.4 t/h. The waste gas that was collected by the kiln system passed through a humidifier tower, and then was dedusted by an electric dust collector. The amount of the ash recycled by the humidifier tower was about 8.6 tons per hour, approximately accounting for 4% by weight of the total amount of raw materials that were fed into the kiln. One single electric dust collector was used by the raw material system and the rear kiln for dust collection. After the raw material mill stopped, the total amount of the kiln system (i.e. the humidifier tower and electric dust collector) was about 15 t/h, approximately accounting for 7% by weight of the raw materials which were fed into the kiln. In the prior art, the recycled ash of the kiln system was fed together with the recycled ash of the raw materials via a raw material powder chute into a raw material homogenizing silo. The kiln condition was merely slightly influenced after the raw material powders were finely adjusted. In the case that the recycled ash of the kiln system was fed directly via a raw material elevator into the kiln when the raw material mill stopped, the kiln condition fluctuated violently, and thus the yield and quality were influenced a lot, frequently generating crusted or wrapped-up unfired clinker. In a manufacture workshop of the cement plant, the blending material and the clinker were ground to be clinker powder and slag powder respectively, and then blended homogeneously in a proper proportion, wherein the slag powder was prepared by blending mineral waste residue, coal cinder, with gypsum followed by grinding. The 42.5-grade cement was blended with 30% by weight of the slag powder and 70% by weight of the clinker powder. The finished 42.5-grade cement had an average initial setting time of 110 minutes, an average final setting time of 175 minutes, an average standard consistency of 22.3%, an average three-day compressive strength of 25.6 MPa, an average three-day rupture strength of 2.9 MPa, an average 28-day compressive strength of 48.9 MPa, and an average 28-day rupture strength of 4.7 MPa. When the cement was used, there was no slurrying, but sugaring appeared.

(86) The method of the present disclosure was used, wherein the recycled ash of the humidifier tower of the kiln system was blended with the modified bentonite with the amount of 12% by weight of the recycled ash, and then conveyed into a steel silo in the manufacture workshop of the cement product to be used as a substituted slag powder. When the raw material mill stopped, the recycled ash that was collected by the humidifier tower and the electric dust collector of the kiln end was fed into a cement mill steel silo to be used as a substituted slag powder. When the blending clinker powder in the 42.5-grade cement was kept unchanged at 70%, the amounts of the slag powder were reduced from 30% to 28%, 26%, 24%, 22%, and 20% by weight, respectively, and the recycled ash modified by the modified bentonite was used to replace 2%, 4%, 6%, 8%, and 10% by weight of the slag powder, respectively, to obtain the 42.5-grade cement with recycled ash modified by modified bentonite as substitute slag powder. Compared with the original 42.5-grade cement containing slag powder with the amount of 30% by weight, the 42.5-grade cement blended with the recycled ash modified by the modified bentonite had an average initial setting time reduced by 5 to 15 minutes, an average final setting time reduced by about 10 minutes, a significantly changed average standard consistency, an average 3-day compressive strength increased by 2-4 MPa, an average 3-day rupture strength increased by 0.3-0.7 MPa, and an average 28-day strength substantially unchanged. When the cement obtained was used, substantially no sugaring or craquelure appeared.

Example 19

(87) In a 4.874 m dry process rotary kiln production line, the average daily output of clinker was 5200 t/d, and the average output per machine hour was 216.7 t/h. The waste gas that was collected by the kiln system passed through a humidifier tower, and then was dedusted by an electric dust collector. The amount of the ash recycled by the humidifier tower was about 12 tons per hour, approximately accounting for 3.5% by weight of the total amount of raw materials that were fed into the kiln. One single electric dust collector was used by the raw material system and the rear kiln for dust collection. After the raw material mill stopped, the total amount of the kiln system (i.e. the humidifier tower and electric dust collector) was about 24 t/h, approximately accounting for 7% by weight of the raw materials fed into the kiln. In the prior art, the recycled ash of the kiln system was fed together with the recycled ash of the raw materials via a raw material powder chute into a raw material homogenizing silo. The kiln condition was merely slightly influenced after the raw material powders were finely adjusted. In the case that the recycled ash of the kiln system was fed directly via a raw material elevator into the kiln when the raw material mill stopped, the kiln condition fluctuated violently, and thus the yield and quality were influenced a lot, frequently generating crusted or wrapped-up unfired clinker. In a manufacture workshop of the cement plant, the blending materials and clinker were ground into cement powder, which was then blended with first level coal ash. That is, 42.5-grade and 32.5-grade cement products were blended with ground clinker powder containing slag and coal ash in different ratios. In the cement mill of the plant, 18% by weight of blending materials (mineral waste residue and coal cinder) batched with gypsum were ground into cement powder, wherein the 42.5-grade cement finished product were blended with 20% by weight of coal ash and 80% by weight of cement powder. The finished 42.5-grade cement had an average initial setting time of 127 minutes, an average final setting time of 198 minutes, an average standard consistency of 22.8%, an average three-day compressive strength of 26.2 MPa, an average three-day rupture strength of 2.8 MPa, an average 28-day compressive strength of 48.7 MPa, and an average 28-day rupture strength of 4.8 MPa. When the cement was used, there was no slurrying, but sugaring appeared.

(88) The method of the present disclosure was used, wherein the recycled ash of the humidifier tower of the kiln system was blended with the modified bentonite with the amount of 15% by weight of the recycled ash, and then conveyed into a steel silo in the manufacture workshop of the cement product to be used as a substituted slag powder. When the raw material mill stopped, the recycled ash that was collected by the humidifier tower and the electric dust collector of the rear kiln was conveyed into a cement mill steel silo to be used as a substituted slag powder. In the 42.5-grade cement, the amount of cement powder was kept at 80% by weight of the cement, while the content of coal ash was reduced from 20% to 17%, 15%, 13%, and 10%, respectively. As a substitute of the reduced coal ash, recycled ash modified by the modified bentonite accounting for 3%, 5%, 7%, and 10% by weight of the cement were added, respectively. Compared with the original 42.5-grade cement containing slag powder with the amount of 20% by weight, the cement blended with the recycled ash modified by the modified bentonite had an average initial setting time reduced by 10 minutes, an average final setting time reduced by about 10 minutes, a significantly changed standard consistency, an average 3-day compressive strength increased by 2-4 MPa, an average 3-day rupture strength increased by 0.3-0.6 MPa, and an average 28-day strength substantially unchanged. Feedback from users indicated that the workability of said cement was obviously improved, and the phenomenon of sugaring substantially disappeared.