阅读说明：本技术 一种纳米水化产物晶核早强剂的制备方法 (Preparation method of nano hydration product crystal nucleus early strength agent ) 是由 杨进 曾景义 范敬源 贺行洋 苏英 王迎斌 陈顺 陈威 李玉博 毛云 于 2020-07-20 设计创作，主要内容包括：本发明公开了一种纳米水化产物晶核早强剂的制备方法,包括：(1)取农业废渣干磨至中值粒径小于20μm；(2)取含Ca的碱性工业废渣、水、助磨剂、促溶剂与研磨介质混合,置于湿磨机中研磨,直至浆料中碱性工业废渣的中值粒径小于20μm；(3)将农业废渣和表面活性剂加入湿磨机,先研磨30min-50min后停10min-15min,之后再每研磨20min-30min停10min-15min,直至浆料中值粒径小于100nm；(4)在步骤(3)所得浆料中加入分散稳定剂,经减压浓缩使浆料固含量达30％-40％。本发明在确保纳米水化产物晶核早强剂早强性能的前提下,还显著降低了生产成本以及工艺复杂程度。(The invention discloses a preparation method of a nano hydration product crystal nucleus early strength agent, which comprises the following steps: (1) taking agricultural waste residues, and dry-grinding the agricultural waste residues until the median particle size is less than 20 mu m; (2) mixing Ca-containing alkaline industrial waste, water, a grinding aid, a dissolution promoter and a grinding medium, and placing the mixture in a wet grinder for grinding until the median particle size of the alkaline industrial waste in the slurry is less than 20 mu m; (3) adding agricultural waste residue and surfactant into a wet grinder, grinding for 30-50 min, stopping for 10-15min, and stopping for 10-15min every 20-30 min until the median particle size of the slurry is less than 100 nm; (4) and (4) adding a dispersion stabilizer into the slurry obtained in the step (3), and concentrating under reduced pressure to enable the solid content of the slurry to reach 30-40%. The invention also obviously reduces the production cost and the process complexity on the premise of ensuring the early strength performance of the nano hydration product crystal nucleus early strength agent.)

1. A method for preparing a nano hydration product crystal nucleus early strength agent is characterized by comprising the following steps:

(1) taking 25-40 parts by weight of agricultural waste residues, and carrying out dry grinding until the median particle size is less than 20 mu m, wherein the agricultural waste residues refer to products obtained by burning agricultural and forestry wastes at 600-800 ℃;

(2) mixing 30-80 parts by weight of Ca-containing alkaline industrial waste residue, 160-280 parts by weight of water, a grinding aid, a dissolution promoter and a grinding medium, and grinding for 10-15min in a wet grinder at a rotating speed of 300-400 rps until the median particle size of the alkaline industrial waste residue in the slurry is less than 20 mu m; the dosage of the grinding aid and the cosolvent is 0.1 to 0.3 percent of the weight of the agricultural waste residue;

(3) adding agricultural waste residues and a surfactant accounting for 0.1-0.3% of the agricultural waste residues in parts by weight into a wet grinder, grinding at a rotating speed of 200rps-300rps for 30-50 min, stopping grinding for 10-15min, and stopping grinding for 10-15min every 20-30 min until the median particle size of the slurry is less than 100 nm; the temperature of the slurry is kept between 80 and 90 ℃ in the grinding process;

(4) and (3) adding a dispersion stabilizer accounting for 0.1-0.3 percent of the weight of the agricultural waste residues into the slurry obtained in the step (3), and carrying out reduced pressure concentration to enable the solid content of the slurry to reach 30-40 percent.

2. The method of claim 1, wherein the method comprises the steps of:

SiO in the agricultural waste residue₂The content is more than 60 percent.

3. The method of claim 1, wherein the method comprises the steps of:

the agricultural waste residue is one or more of straw ash, bagasse and rice hull ash which are obtained by burning straws, bagasse and rice hulls at a high temperature of 600-800 ℃.

4. The method of claim 1, wherein the method comprises the steps of:

the solid content of the alkaline industrial waste residue is 50-90%, 30-80 parts by weight of the alkaline industrial waste residue is mixed with 280 parts by weight of water to obtain slurry Ca (OH)₂The content is 8-16%.

5. The method of claim 1, wherein the method comprises the steps of:

the alkaline industrial waste residue is one or more of carbide slag and grain slag.

6. The method of claim 1, wherein the method comprises the steps of:

the grinding aid is one or more of triethanolamine and diethanolamine.

7. The method of claim 1, wherein the method comprises the steps of:

the cosolvent is one or more of propylene glycol and an organic silicon cosolvent.

8. The method of claim 1, wherein the method comprises the steps of:

the grinding medium comprises 300-400 parts by weight of zirconia balls and 100-150 parts by weight of agate balls; wherein:

the zirconia balls comprise zirconia small balls with the ball diameter of 0.5mm-1.0mm, zirconia middle balls with the ball diameter of 1.0mm-3.0mm and zirconia big balls with the ball diameter of 3.0mm-5.0mm, and the mass fractions of the zirconia small balls, the zirconia middle balls and the zirconia big balls are respectively 40.0% -75.0%, 17.5% -30.0% and 17.5% -30.0%;

the diameter of the agate ball is 5.0mm-10.0 mm.

9. The method of claim 1, wherein the method comprises the steps of:

the surfactant is one or more of polycarboxylic acid series, polyacrylic acid series and aliphatic hydroxymethyl sulfonic acid series additives.

10. The method of claim 1, wherein the method comprises the steps of:

and (4) in the grinding process of the step (3), intermittently introducing a cooling medium into the wet grinder to keep the temperature of the slurry at 80-90 ℃.

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to a preparation method of a nano hydration product crystal nucleus early strength agent.

Background

With the continuous development of the building industry in China, the application of projects such as road bridges, prefabricated houses, urban subway tunnels and the like is continuously increased. In order to accelerate the turnover of the template and improve the production efficiency, the steam thermal curing technology is generally adopted to improve the early strength of the concrete at present, but the structure of a hydration product has defects, and the later strength and the durability of the concrete are not good. Meanwhile, the early strength of the concrete is often improved by adding an inorganic early strength agent, which introduces ions harmful to the concrete and has negative effects on the appearance and durability of the concrete. The nano material has the characteristics of better induction of hydration, promotion of early strength and no side effect, such as nano calcium silicate hydrate (C-S-H) crystal nucleus. The classical C-S-H gel growth theory proposes that the induction period of cement hydration and the reaction rate of an accelerator are controlled by C-S-H nucleation and growth, and the early performance of cement can be greatly improved by adding nano calcium silicate hydrate crystal nuclei.

Common preparation methods of the nano calcium silicate hydrate include a chemical precipitation method and a hydrothermal method. Chinese patent CN201410591887.6 discloses an early strength agent of calcium silicate hydrate gel solution, which is prepared by mixing and reacting calcium nitrate, sodium silicate, naphthalenesulfonate formaldehyde condensate dispersant and water. Chinese patent CN201810938926.3 discloses a preparation method of a nano C-S-H gel material, which comprises the steps of putting a mixed solution of sodium silicate, calcium nitrate and sodium hydroxide into a reaction kettle, heating for reaction, and carrying out centrifugal washing after the reaction is finished. The chemical precipitation method needs too long time and low benefit, the hydrothermal method has harsh reaction conditions and high energy consumption, and the raw materials of the two methods are expensive, so the two methods are not beneficial to popularization and application in the concrete industry.

At present, the nano calcium silicate hydrate also has a novel preparation method, such as: chinese patent CN201610888588.8 discloses an early strength concrete admixture and a preparation method thereof, calcium nitrate tetrahydrate, an emulsifier, a nonpolar solvent, ammonia water and water are mixed, stirred at a high speed at 25 ℃ for pre-emulsification and then ultrasonically emulsified to obtain an emulsion, tetraethyl orthosilicate is slowly dripped into the emulsion to react for 24 hours, and then the temperature is raised to 80 ℃ for demulsification to prepare a dispersion of hydrated calcium silicate hollow nano particles. Chinese patent CN201711331837.4 discloses a preparation method of calcium silicate hydrate early strength agent, which is prepared by adopting acid treatment of waste rice hulls and waste liquid for producing calcium lignosulphonate, and stirring the waste liquid for 12 to 24 hours step by step at constant temperature in a magnetic stirrer with the constant temperature of 60 ℃; and then carrying out suction filtration, washing and impurity removal on the obtained solution to obtain the calcium silicate hydrate early strength agent. However, the above method has complicated manufacturing process, takes a long time to manufacture, and is difficult to produce in a large scale.

Although the nano calcium silicate hydrate has an excellent effect of inducing early hydration of cement, the popularization and application of the nano calcium silicate hydrate are limited due to the problems of expensive preparation raw materials, complex process, high energy consumption, long time consumption, low yield and the like.

The straw ash, rice hull ash and bagasse ash are waste residues generated by burning straw, rice hull and bagasse. When the biomass fuel is used as biomass fuel for combustion power generation, the boiler temperature is approximately 600-800 ℃, most of organic matters such as lignin and cellulose are decomposed and burnt out, and the main component of the biomass fuel is SiO₂The porous framework has good volcanic ash activity, and can be used as a building cementing material. The carbide slag (CaO as main component) is industrial waste slag generated by PVC raw material prepared by calcium carbide hydrolysis, and the water slag (CaO and SiO as main components)₂And Al₂O₃) Also called as blast furnace slag, is a granulated slag formed by rapidly cooling with water in a high-temperature molten state in an iron-making process. The carbide slag and the grain slag are both wet discharged alkaline solid wastes, and have higher water content, higher pH value and rich Ca²⁺Content, has potential as a building cementitious material. China is a big agricultural and industrial country, and agricultural and industrial waste residues are stockpiled for a long time, so that the method not only occupies a large amount of land, but also causes ecological pollution, and therefore, the method for effectively and comprehensively utilizing the waste residues has great significance.

Disclosure of Invention

The invention aims to provide a preparation method of a nano hydration product crystal nucleus early strength agent, which has the advantages of simple process, low cost and low energy consumption, and the obtained nano hydration product crystal nucleus early strength agent can obviously promote the early strength performance of cement.

The invention provides a preparation method of a nano hydration product crystal nucleus early strength agent, which comprises the following steps:

(1) taking 25-40 parts by weight of agricultural waste residues, and carrying out dry grinding until the median particle size is less than 20 mu m, wherein the agricultural waste residues refer to products obtained by burning agricultural and forestry wastes at 600-800 ℃;

(2) mixing 30-80 parts by weight of Ca-containing alkaline industrial waste residue, 160-280 parts by weight of water, a grinding aid, a dissolution promoter and a grinding medium, and grinding for 10-15min in a wet grinder at a rotating speed of 300-400 rps until the median particle size of the alkaline industrial waste residue in the slurry is less than 20 mu m; the dosage of the grinding aid and the cosolvent is 0.1 to 0.3 percent of the weight of the agricultural waste residue;

(3) adding agricultural waste residues and a surfactant accounting for 0.1-0.3% of the agricultural waste residues in parts by weight into a wet grinder, grinding at a rotating speed of 200rps-300rps for 30-50 min, stopping grinding for 10-15min, and stopping grinding for 10-15min every 20-30 min until the median particle size of the slurry is less than 100 nm; the temperature of the slurry is kept between 80 and 90 ℃ in the grinding process;

(4) and (3) adding a dispersion stabilizer accounting for 0.1-0.3 percent of the weight of the agricultural waste residues into the slurry obtained in the step (3), and carrying out reduced pressure concentration to enable the solid content of the slurry to reach 30-40 percent.

Preferably, the SiO in the agricultural waste residue₂The content is more than 60 percent.

Further, the agricultural waste residue is one or more of straw ash, bagasse and rice hull ash which are obtained by burning straws, bagasse and rice hulls at a high temperature of 600-800 ℃.

Preferably, the solid content of the alkaline industrial waste residue is 50-90%, 30-80 parts by weight of the alkaline industrial waste residue is mixed with 160-280 parts by weight of water to obtain slurry, wherein the slurry contains Ca (OH)₂The content is 8-16%.

Further, the alkaline industrial waste residue is one or more of carbide slag and grain slag.

Further, the grinding aid is one or more of triethanolamine and diethanolamine.

Further, the dissolution promoter is one or more of propylene glycol and an organic silicon dissolution promoter.

Preferably, the grinding medium comprises 300-400 parts by weight of zirconia balls and 100-150 parts by weight of agate balls; wherein:

the zirconia balls comprise zirconia small balls with the ball diameter of 0.5mm-1.0mm, zirconia middle balls with the ball diameter of 1.0mm-3.0mm and zirconia big balls with the ball diameter of 3.0mm-5.0mm, and the mass fractions of the zirconia small balls, the zirconia middle balls and the zirconia big balls are respectively 40.0% -75.0%, 17.5% -30.0% and 17.5% -30.0%;

the diameter of the agate ball is 5.0mm-10.0 mm.

Further, the surfactant is one or more of polycarboxylic acid series, polyacrylic acid series and aliphatic hydroxymethyl sulfonic acid series additives.

Further, in the grinding process of the step (3), the temperature of the slurry is maintained to be 80-90 ℃ by intermittently introducing a cooling medium into the wet grinder.

The invention provides a silicon source by using agricultural waste residues, provides a calcium source by using Ca-containing alkaline industrial waste residues, increases the pH value, and performs a volcanic ash reaction in a wet grinder under a liquid phase environment to prepare the nano C-S-H. The pozzolan reaction formula is: x Ca (OH)₂+y SiO₂+zH₂O→x CaO·y SiO₂·(x+z)H₂And O. The invention not only solves the problem of utilization of solid wastes, but also reduces the production cost of the nano C-S-H.

In the step (1), the agricultural waste residues obtained by calcining the straws, the rice husks, the bagasse and the like also retain the original tissue skeleton, and the original loose porous structure of the agricultural waste residues is damaged by grinding, so that powder with uniform particle size distribution is obtained and can be used as a silicon source for the volcanic ash reaction.

In the step (2), adding water into the alkaline wet-discharge industrial waste residue to adjust the alkaline wet-discharge industrial waste residue to a proper solid content, adding a grinding aid to improve the grinding efficiency, and adding a dissolution promoter to promote Ca²⁺With OH^-Can be used as Ca for volcanic ash reaction²⁺Source and OH^-A source. During grinding, the grinding rotating speed is high, the particle size of the alkaline industrial waste residue can be quickly reduced, and ions in the alkaline industrial waste residue can be quickly dissolved out; in addition, higher grinding speeds increase the slurry temperature, thereby providing the activation energy required for the pozzolanic reaction.

In the step (3), adding a silicon source, grinding for 30min-50min to refine the particles, and then pausing for 10min-15min and pausing for 10min-15min every 20min-30min of grinding so as to enable the calcium silicate hydrate to be in SiO₂Surface growth, grinding for 20min-30min to obtain SiO₂Excess calcium silicate hydrate on the surface is removed, so that the reaction can be continued. This mechanism is illustrated in figure 1.

Because the wet grinder forms the rotation turbulence with outstanding anisotropic characteristic under the common influence of strong rotation, large curvature and multi-wall surface in the high-speed rotation process, the flow separation and strong shearing flow generated by the rotation turbulence form a turbulence high-pressure area in the liquid phase environment of the wet grinder, simultaneously greatly increases the friction resistance and energy loss of grinding media, generates higher heat energy, and ensures that the temperature rising rate of the slurry is more than or equal to the rate of radiating to the external environment. Intermittently introducing cooling water to keep the temperature to be proper for reaction; meanwhile, due to mechanical acting forces such as shearing, impact, friction and the like generated by a wet grinding medium in a wet grinder, the particles are continuously ground, fractured and refined, so that a large number of crystal lattice defects and nanometer crystal boundaries are generated on the particles, and the activity of the particles is greatly improved; the nanometer hydrated calcium silicate early strength agent is prepared by means of the specific high pressure and damp-heat environment of wet grinding and mechanochemical synthesis reaction.

In the step (5), the dispersion stabilizer is added, so that the agglomeration generated in the concentration and storage processes of the slurry can be effectively controlled. Meanwhile, the characteristic that the temperature of the slurry is high after the preparation is finished is fully utilized, the gas pressure is reduced to 40KPa, the boiling point of water is reduced (the boiling point of water is 76 ℃ when the gas pressure is 40 KPa), the water is evaporated, and the preparation and concentration of the calcium silicate hydrate are continuously carried out.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the traditional dry grinding process generates a great deal of heat energy loss and kinetic energy loss in the grinding process, however, a wet grinding process adopting wet medium grinding can effectively absorb and utilize the loss of heat energy and kinetic energy to accelerate the reaction rate, namely, the lost heat energy is absorbed by utilizing the inherent water content of the wet grinding to form a higher-temperature reaction environment, and the growth and the formation of calcium silicate hydrate crystal nuclei are promoted by utilizing the mechanical kinetic energy generated by shearing and impacting of the wet grinding medium and the high-pressure environment generated by rotating turbulence in a wet grinder. The invention organically combines the grinding of raw materials and the synthesis of calcium silicate hydrate in a set of wet grinding process, and provides a preparation method integrating grinding and synthesis, thereby simplifying the preparation process of calcium silicate hydrate. Meanwhile, due to the higher solution temperature (80-90 ℃) generated by grinding, after the preparation is finished, the water can be evaporated without heating and reducing the gas pressure, and a product treatment method for continuous preparation and concentration is provided, so that the energy consumption generated by concentration is reduced.

The invention takes agricultural waste residues such as platycodon grandiflorum ash, rice hull ash, bagasse ash and the like and alkaline industrial waste residues such as carbide slag, water granulated slag and the like as raw materials, and takes active SiO generated by agricultural incineration solid waste₂And Ca in alkaline industrial residues²⁺And OH^-The nano calcium silicate hydrate is prepared by using the nano calcium silicate hydrate as a raw material for volcanic ash reaction, so that a comprehensive utilization method of industrial and agricultural solid wastes is provided, the production cost of the calcium silicate hydrate is reduced, and the added value of the product is increased.

Drawings

FIG. 1 is a mechanism diagram of mechanochemical synthesis of nano calcium silicate hydrate (C-S-H) in a wet grinder.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following further provides embodiments and examples of the present invention. It should be understood that the detailed description and specific examples, while indicating the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

In the specific embodiment, the embodiment and the comparative example, the agricultural waste residue is from various thermal power plants, the carbide slag and the water slag are from various acetylene plants and metallurgical plants prepared by a carbide method, the silica fume, the calcium hydroxide and the additive are all commercially available, and the wet grinder is a vertical planetary ball mill.

The specific embodiment of preparing the nano hydration product crystal nucleus early strength agent comprises the following steps:

(1) and (3) taking 25-40 parts by weight of agricultural waste residues, and dry-grinding until the median particle size is less than 20 mu m.

The agricultural waste residue refers to a product obtained by burning agricultural and forestry wastes (such as straws, bagasse, rice hulls and the like) at the temperature of 600-800 ℃, and the agricultural waste residue is preferably SiO₂Agricultural waste residue with content more than 60%. In the specific embodiment, the agricultural waste residue is selected from straw ash, bagasse ash, rice hull ash and the like obtained by high-temperature incineration at 600-800 ℃. At present, a thermal power plant adopts biomass fuel to burn for power generation, the biomass fuel is mainly agricultural and forestry waste, and the burning temperature is approximately 600-800 ℃, so that the agricultural waste residues can be directly taken from the biomass fuel waste residues of the thermal power plant.

(2) Mixing 30-80 parts by weight of Ca-containing alkaline industrial waste residue, 160-280 parts by weight of water, a grinding aid and a dissolution promoter with 550 parts by weight of 400-550 parts by weight of grinding medium, and grinding for 10min-15min in a wet grinder at a rotating speed of 300rps-400rps until the median particle size of the alkaline industrial waste residue in the slurry is less than 20 mu m; wherein the dosage of the grinding aid and the cosolvent is 0.1 to 0.3 percent of the weight of the agricultural waste residue. The temperature of the slurry in the grinding process reaches 80-90 ℃.

The solid content of the adopted alkaline industrial waste residue is preferably 50-90%. And it and 160-280 parts by weight of water Ca (OH) in the slurry₂The content is preferably 8% to 16%. In the specific embodiment, the alkaline industrial waste residue is one or more of carbide slag and grain slag. The grinding aid is used for improving grinding efficiency, and specifically one or more of triethanolamine and diethanolamine can be adopted. The dissolution promoter is used for promoting the dissolution of Ca in the alkaline industrial waste residue²⁺And OH^-Propylene glycol or silicone dissolution promoters may be used in particular.

Preferably, the grinding media comprise 300-400 parts by weight zirconia balls and 100-150 parts by weight agate balls. Wherein, the zirconia balls comprise zirconia small balls with the ball diameter of 0.5mm to 1.0mm, zirconia middle balls with the ball diameter of 1.0mm to 3.0mm and zirconia big balls with the ball diameter of 3.0mm to 5.0mm, and the mass fractions of the zirconia small balls, the zirconia middle balls and the zirconia big balls are respectively 40.0 percent to 75.0 percent, 17.5 percent to 30.0 percent and 17.5 percent to 30.0 percent; the diameter of the agate ball is 5.0mm-10.0 mm.

(3) Adding the agricultural waste residue and the surfactant obtained in the step (1) into a wet grinder for continuous grinding, grinding at a rotating speed of 200rps-300rps for 30-50 min, stopping grinding for 10-15min, and stopping grinding for 10-15min every 20-30 min until the median particle size of the slurry is less than 100 nm; keeping the temperature of the slurry at 80-90 ℃ in the grinding process; the dosage of the surfactant is 0.1-0.3% of the agricultural waste residue.

In this embodiment, the surfactant may be one or more of polycarboxylic acid-based, polyacrylic acid-based, and aliphatic hydroxymethanesulfonic acid-based additives.

The temperature of the slurry is kept between 80 and 90 ℃ during the grinding process, and the temperature can be realized by intermittently introducing a cooling medium into the wet grinder. For example, cold air of 0-10 ℃ can be introduced into the wet grinder by using an external air conditioner or cooling water of 0-10 ℃ can be introduced into the wet grinder by using an external condenser through a cooling water pipe, so that the temperature of the slurry during grinding is kept at 80-90 ℃, and the appropriate reaction temperature is obtained.

(4) And (3) adding a dispersion stabilizer accounting for 0.1-0.3% of the weight of the agricultural waste residues into the slurry obtained in the step (3), and concentrating under reduced pressure to enable the solid content of the slurry to reach 30-40% to obtain the nano hydration product crystal nucleus early strength agent.

In this embodiment, the dispersion stabilizer may be one or more of naphthalenesulfonate, fatty acids, and polyacrylamide additives; the pressure intensity of the reduced pressure concentration is less than 40KPa, and the reduced pressure concentration device or reduced pressure distillation device can be adopted for the reduced pressure concentration.

FIG. 1 is a mechanism diagram of mechanochemical synthesis of nano calcium silicate hydrate in a wet grinder according to the invention. Mixing and wet grinding the agricultural waste residue and the alkaline industrial waste residue to refine the agricultural waste residue to prepare SiO with higher volcanic ash activity₂And simultaneously quickening Ca in the alkaline industrial waste residue²⁺And OH^-And (4) dissolving out. When the wet grinder stops operating, Ca is used by virtue of the specific damp-heat environment in the wet grinder²⁺And OH^-Attached to active SiO₂And carrying out surface reaction to generate the C-S-H gel film. When the wet grinder is running again, under the continuous shearing, impact and friction of the grinding medium, SiO₂The C-S-H gel film on the surface is separated to form nano C-S-H crystal nucleus and newly exposed SiO₂Refining and activating again under the action of grinding medium, and continuously supplementing Ca to the alkaline industrial waste residue under the action of grinding medium²⁺And OH^-In preparation for the next C-S-H gel film formation. Repeated stopping and running of the wet grinder, SiO₂The nano C-S-H crystal nucleus is continuously consumed and increased, and finally the nano C-S-H is prepared.

Examples of the present invention and comparative examples will be provided continuously below.