阅读说明：本技术 一种聚合硫酸铝溶液的制备方法和无碱液体速凝剂 (Preparation method of polyaluminum sulfate solution and alkali-free liquid accelerator ) 是由 杨春明 任俊 陈庆蓉 于 2021-02-18 设计创作，主要内容包括：本发明公开了一种聚合硫酸铝溶液的制备方法,包括：在硫酸铝溶液中加入固体碱化剂(不含碱金属的固体碱化剂),当固体碱化剂加完后继续反应完全,降温,出料,得到聚合硫酸铝溶液。本发明还公开了一种无碱液体速凝剂,采用该制备方法制备获得的聚合硫酸铝溶液作为主促凝剂。本发明使用不含碱金属的固体碱化剂替代传统的含有碱金属离子的强碱及其盐类(如NaOH、KOH、Na-2CO-3、NaHCO-3、NaAlO-2),也不使用在硫酸盐体系中容易产生沉淀的Ca(OH)-2等碱化剂,实现了产品碱化度可控,不会产生影响混凝土后期强度的杂质离子,也不会产生沉淀物及废渣,缩短了制备工艺,降低成本,并且制备工艺环保。(The invention discloses a preparation method of polyaluminium sulfate solution, which comprises the following steps: adding a solid alkalizer (a solid alkalizer without alkali metal) into the aluminum sulfate solution, continuing to react completely after the solid alkalizer is added, cooling, and discharging to obtain the polyaluminum sulfate solution. The invention also discloses an alkali-free liquid accelerator, and the polyaluminium sulfate solution prepared by the preparation method is used as a main accelerator. The invention uses solid alkalizer without alkali metal to replace traditional alkali containing alkali metal ion and its salt (such as NaOH, KOH, Na) 2 CO 3 、NaHCO 3 、NaAlO 2 ) Ca (OH) which easily causes precipitation in a sulfate system is not used 2 The equivalent alkalizer realizes the controllability of the alkalization degree of the product, and does not influence the later strength of the concreteImpurity ions do not generate precipitates and waste residues, the preparation process is shortened, the cost is reduced, and the preparation process is environment-friendly.)

1. A method for preparing polyaluminium sulfate solution, comprising: adding a solid alkalizer into an aluminum sulfate solution, continuing to react completely after the solid alkalizer is added, cooling, discharging to obtain a polymeric aluminum sulfate solution, wherein the polymeric aluminum sulfate solution is used for an alkali-free liquid accelerator, and the method is characterized in that the alkali-free solid alkalizer is used as the solid alkalizer for preparing the polymeric aluminum sulfate solution, and the alkali-free solid alkalizer is one or more of alkali-free metal oxide, alkali-free alkali or alkali-free alkali carbonate; wherein the alkali-free metal oxide is one or more selected from MgO, CuO and ZnO, and the alkali-free alkali is selected from Mg (OH)₂、Cu(OH)₂And Zn (OH)₂The alkali metal-free basic carbonate is selected from one or more of basic magnesium carbonate, basic copper carbonate and basic zinc carbonate.

2. The method of claim 1, wherein the solid alkalizer is used in an amount to control the alkalization degree of the polyaluminium sulfate solution to be between 10% and 50%.

3. The preparation method of claim 1, wherein the solid alkalizer is added in batches, the reaction is continued for 30-60 min after the solid alkalizer is added, and the temperature for adding the solid alkalizer for reaction is 60-80 ℃.

4. An alkali-free liquid accelerator, characterized in that the polyaluminium sulfate solution prepared by the preparation method of any one of claims 1 to 3 is used as a main accelerator.

5. The alkali-free liquid accelerator according to claim 4, wherein the alkali-free liquid accelerator consists essentially of the polyaluminium sulfate solution, a stabilizer and a co-accelerator, wherein the stabilizer is montmorillonite or silica sol.

6. The alkali-free liquid accelerator according to claim 4, wherein the addition amount of the silica sol in the stabilizer accounts for 3-4% of the mass of the accelerator; the addition amount of the montmorillonite in the stabilizer accounts for 4-6% of the mass of the accelerating agent.

7. The alkali-free liquid accelerator according to claim 4, wherein the montmorillonite in the stabilizer is a calcium-based montmorillonite dispersion.

8. The alkali-free liquid accelerator according to claim 4, wherein the auxiliary accelerator is selected from triethanolamine or polyphosphoric acid; the addition amount of the triethanolamine accounts for 0.2 to 0.4 percent of the mass of the accelerator; the addition amount of the polyphosphoric acid accounts for 1% -2% of the mass of the accelerator.

Technical Field

The invention belongs to the field of inorganic non-metallic materials, and particularly relates to a preparation method of a polyaluminium sulfate solution for an alkali-free liquid accelerator and the alkali-free liquid accelerator.

Background

The concrete accelerator is also called cement accelerator, is a chemical additive which can promote the cement or concrete to be quickly coagulated and hardened and can produce a certain strength in a short time, and is widely applied to the aspects of anchor-jet support, plugging and rush-repair engineering and the like of underground engineering such as tunnels, culverts, mine roadways and the like. Particularly, the liquid accelerator makes the concrete spraying construction possible, and plays an important role in establishing a roadway anchor-spraying supporting technology. Although the variety of the accelerating agent on the market is various, due to strict requirements on environmental protection, the accelerating agent is converted from an initial solid powder into a liquid, and the liquid is converted from a strong alkali and a low alkali to an alkali-free accelerating agent.

The alkali-free accelerator is adopted to replace the traditional alkali accelerator, mainly based on avoiding the later strength loss of concrete caused by alkali aggregate reaction in the presence of strong alkali, and the liquid accelerator is used to replace solid powder, mainly based on the consideration of facilitating wet spraying construction and improving the working environment. The national standard GB/T35159-₂O+0.658K₂O) is less than 1%.

In the prior art, the alkali-free liquid accelerator usually uses aluminum sulfate and the like as main accelerating components to replace the traditional NaAlO₂Although the aluminium sulfate salt is easy to dissolve in water, its solubility is limited, especially the stability of high-concentration liquid is poor, and the polyaluminium sulfate is a high-molecular compound made up by using aluminium sulfate and alkalizer through the processes of reaction at a certain temp. and curing, and its stability under a certain alkalinity is higher than that of general aluminium sulfate. The general industrial production is that aluminum sulfate and lime water Ca (OH)₂The solution is reacted, but the generated CaSO as a byproduct needs to be removed by filtration after the reaction is finished₄Thereby causing environmental problems such as waste residue discharge and the like. CN105271867A discloses a novel alkali-free liquid accelerator based on synthetic polyaluminium sulfate, which is prepared by adopting a two-step method: the first step utilizes ammonia water to neutralize aluminum sulfate to generate active aluminum hydroxide, and the second step is to react the separated active aluminum hydroxide with aluminum sulfate to prepare polyaluminum sulfate, so that a large amount of ammonium sulfate as a byproduct exists, and the ammonia water has environmental protection problems such as volatilization in the operation. CN107512730A discloses a method for preparing polyaluminium sulfate by using aluminium sulfate and calcium aluminate as raw materials, but the generated calcium sulfate by-product is removed by filtration. Part of researchers have studied using alkali containing alkali metal ions and salts thereofClass (e.g. NaOH, KOH, Na)₂CO₃、NaHCO₃、NaAlO₂) The reaction of the alkalizer and aluminum sulfate is easy to cause Na which cannot be removed in the prepared polyaluminum sulfate solution⁺、K⁺Ions, thereby causing alkali aggregate reaction and causing excessive loss of later strength of the concrete.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects and shortcomings in the background art, and provide a preparation method of polyaluminium sulfate solution for an alkali-free liquid accelerator and the alkali-free liquid accelerator.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

a method for preparing a polyaluminium sulfate solution for an alkali-free liquid accelerator, comprising: adding a solid alkalizer into an aluminum sulfate solution, continuing to react completely after the solid alkalizer is added, cooling, discharging to obtain a polyaluminum sulfate solution, wherein the solid alkalizer for preparing the polyaluminum sulfate solution adopts an alkali-free solid alkalizer, and the alkali-free solid alkalizer is one or more of alkali-free metal oxide, alkali or alkali-free basic carbonate; the alkali metal-free metal oxide is selected from one or more of MgO, CuO and ZnO; the alkali-free base is selected from Mg (OH)₂、Cu(OH)₂And Zn (OH)₂One or more of the above; the alkali metal-free basic carbonate is selected from one or more of basic magnesium carbonate, basic copper carbonate and basic zinc carbonate. Further preferably, the solid alkalizer is selected from Mg (OH)₂And one or two of basic magnesium carbonate.

The above preparation method, preferably, comprises: and under the condition of stirring, adding the solid alkalizer into the aluminum sulfate solution in batches, continuing to react for 30-60 min after the solid alkalizer is added, cooling, and discharging to obtain the polyaluminum sulfate solution for the alkali-free liquid accelerator.

In the preparation method, the preferable temperature for adding the solid alkalizer to carry out the reaction is 60-80 ℃. Further preferably, the reaction temperature is 65-75 ℃ with better effect.

In the above preparation method, preferably, the aluminum sulfate solution is obtained by dissolving industrial aluminum sulfate raw material octadecahydrate in water; with Al₂O₃The content of the aluminum sulfate solution is 1% -8%.

In the preparation method, preferably, the dosage of the solid alkalizer is based on controlling the alkalization degree of the polyaluminium sulfate to be between 10% and 50%. Further preferably, the use amount of the solid alkalizer controls the alkalization degree of the polyaluminium sulfate to be 30-45%.

As a general inventive concept, the present invention also provides an alkali-free liquid accelerator using the polyaluminum sulfate solution prepared by the above-mentioned preparation method as a main accelerator.

The alkali-free liquid accelerator is preferably composed of the polyaluminium sulfate solution, a stabilizer and a co-accelerator, wherein the stabilizer is montmorillonite and silica sol.

Preferably, the addition amount of the silica sol in the stabilizer accounts for 3-4% of the mass of the accelerator; the addition amount of the montmorillonite in the stabilizer accounts for 4-6% of the mass of the accelerating agent. The addition amount of the montmorillonite is required to be selected within a specific range of the invention, the addition amount is too small, the stabilizing effect on the accelerating agent is not good, and the accelerating effect of the accelerating agent is influenced by too much addition amount.

Preferably, the alkali-free liquid accelerator is prepared by hydrolyzing Tetraethoxysilane (TEOS) under acidic condition, and the adding concentration of the TEOS in the hydrolysis process of the TEOS is 0.3-0.4 mol.L^-1The hydrolysis temperature is 40-70 ℃, the hydrolysis time is 20-40min, and the addition amount of acid accounts for 2-6% of the mass of the ethyl orthosilicate.

The alkali-free liquid accelerator is preferably used, and the concentration of silica sol is 16-22 g/L.

Preferably, the montmorillonite is a calcium-based montmorillonite dispersion liquid. Further preferably, the mass percentage concentration of the calcium-based montmorillonite dispersion liquid is 25-40%. Because the montmorillonite powder has strong adsorption property, the montmorillonite powder is difficult to be uniformly dispersed when being directly added into a high-concentration PAS solution. Therefore, the montmorillonite-montmorillonite composite material adopts the montmorillonite dispersion liquid, namely montmorillonite is added into water and stirred and dispersed for 12 hours at the temperature of 60 ℃, and the appearance of the montmorillonite dispersion liquid is uniform milky white and is alkalescent. In addition, the applicant also finds that the calcium-based montmorillonite is selected to improve the stabilizing effect of the inorganic accelerator more than other montmorillonite.

The alkali-free liquid accelerator is preferably selected from triethanolamine or polyphosphoric acid.

Preferably, the addition amount of the triethanolamine is 0.2-0.4% of the mass of the accelerator. The triethanolamine has a wetting effect, so that the accelerator has a better wetting effect on cement particles, the reaction barrier of active aluminum and cement is reduced, the coagulation accelerating effect of the PAS accelerator is improved, the coagulation time is shortened, and the triethanolamine can form stable complexes with metal cations in the cement and the accelerator, promote the formation of ettringite and promote the coagulation of the cement. The triethanolamine has a remarkable promoting effect on the strength of PAS accelerator cement mortar.

The alkali-free liquid accelerator is preferably prepared from polyphosphoric acid, wherein the addition amount of polyphosphoric acid accounts for 1-2% of the mass of the accelerator. The polyphosphoric acid has obvious effect of improving the setting performance of the accelerator and the strength of cement mortar, on the one hand, because of HPO₄ ^2-Complexing with Al-OH on the PAS promotes the coagulation of the setting accelerator, on the other hand because of HPO₄ ^2-With Ca in cement²⁺By binding of (C)₃Hydration of S results in increased coagulation efficiency.

Compared with the prior art, the invention has the advantages that:

(1) the invention uses metal oxide, medium and strong base, weak base and basic salt without alkali metal ion to replace the traditional strong base and salt (such as NaOH, KOH, Na) containing alkali metal ion₂CO₃、NaHCO₃、NaAlO₂) Nor in sulfuric acidCa (OH) easily causing precipitation in salt system₂And the alkalization agent is used for realizing the controllability of the alkalization degree of the product, generating no impurity ions influencing the later strength of the concrete, generating no precipitate or waste residue, shortening the preparation process, reducing the cost and protecting the environment of the preparation process.

(2) The polyaluminum sulfate product is a semitransparent or transparent liquid, is weakly acidic (pH3-4), has good homogeneity and stable storage at room temperature, and can meet the requirement of producing an alkali-free liquid accelerator.

(3) The by-product generated in the preparation process of the invention is MgSO (MgSO) with higher solubility in aqueous solution₄、CuSO₄Or ZnSO₄The waste residue does not need to be separated, and the byproducts have certain promotion effect on the early strength of the polyaluminium sulfate accelerator.

(4) The preparation process is simple, the preparation of the polyaluminium sulfate can be completed in a reaction kettle at one time, and a complex post-treatment process is not needed.

(5) Compared with the conventional polyaluminium sulfate, the polyaluminium sulfate prepared by the method has obvious acceleration effect on the accelerating effect of the accelerating agent.

(6) Montmorillonite and silica sol are adopted as the composite stabilizer in the alkali-free liquid accelerator, compared with a single stabilizer, the stabilization period of the PAS solution is increased by 10%, and the stabilized PAS solution of the composite stabilizer has a longer stabilization period, which shows that the two stabilizers have a certain synergistic effect. The stability improvement is attributed to that Si-OH is inserted into a PAS chain segment to form a stable Si-O-Al framework with Al-OH and improve the stability of the PAS solution, and is attributed to that calcium-based montmorillonite dispersed in water is inserted into a lamellar structure with Al-OH on part of PAS chain segments to form a stable structure and improve the stability of the PAS solution, and the two structures are used for improving the stability of the PAS solution.

(7) The invention selects montmorillonite and silica sol as composite stabilizer, which can solve the problem of poor stability of polyaluminium sulfate, and the quick-setting accelerator can realize quick setting and hardening of cement paste or concrete and generate early strength at low dosage.

(8) The invention selects montmorillonite and silica sol as composite stabilizer, which can greatly improve the stabilization time of the accelerator, and can improve the stabilization effect of the accelerator by matching with the auxiliary accelerator so as to improve the coagulation efficiency.

Detailed Description

In order to facilitate an understanding of the present invention, the present invention will be described more fully and in detail with reference to the preferred embodiments, but the scope of the present invention is not limited to the specific embodiments below.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

The invention will be further illustrated by the following examples and comparative examples (raw material ratios are designed according to the production of 1000 kg of product).

Example 1:

the addition proportions of the raw materials used in this example were: aluminum sulfate octadecahydrate: 28%, magnesium hydroxide: 2.5%, water: 69.5 percent.

The preparation method of the polyaluminium sulfate solution for the alkali-free liquid accelerator comprises the following steps:

firstly, 695 kg of water is added into a reaction kettle, the temperature is raised to 60 ℃, 280 kg of aluminum sulfate octadecahydrate is added under stirring, after the dissolution is finished, 25 kg of Mg (OH) is added in batches according to the principle of first-speed and second-speed₂Solid, controlling the reaction temperature at 65-70 ℃, and Mg (OH)₂And after the addition is finished, continuing to react for 40min, cooling after the solution is clarified, and discharging to obtain the polyaluminium sulfate solution for the alkali-free liquid accelerator.

Example 2:

the addition proportions of the raw materials used in this example were: aluminum sulfate octadecahydrate: 40%, basic copper carbonate: 5% and water: and 55 percent.

The preparation method of the polyaluminium sulfate solution for the alkali-free liquid accelerator comprises the following steps:

firstly, 550 kg of water is added into a reaction kettle, the temperature is raised to 60 ℃, 400 kg of aluminum sulfate octadecahydrate is added under stirring, after the dissolution is finished, 50 kg of basic copper carbonate solid is added in batches according to the principle of first-speed and second-speed, the reaction temperature is controlled to be 70-80 ℃, the reaction is continued for 45 min after the addition is finished, the temperature is reduced after the solution is clarified, and the material is discharged, so that the polyaluminum sulfate solution for the alkali-free liquid accelerator is obtained.

Example 3:

the addition proportions of the raw materials used in this example were: aluminum sulfate octadecahydrate: 33.3%, basic zinc carbonate: 6.5%, water: 60.2 percent.

The preparation method of the polyaluminium sulfate solution for the alkali-free liquid accelerator comprises the following steps:

adding 602 kg of water into a reaction kettle, heating to 60 ℃, adding 333 kg of aluminum sulfate octadecahydrate under stirring, adding 65 kg of basic zinc carbonate solid in batches according to the principle of first-speed and second-speed after the dissolution is finished, controlling the reaction temperature to be 70-75 ℃, continuing to react for 55 min after the addition is finished, cooling after the solution is clarified, and discharging to obtain the polyaluminum sulfate solution for the alkali-free liquid accelerator.

Example 4:

the addition proportions of the raw materials used in this example were: aluminum sulfate octadecahydrate: 20%, zinc hydroxide: 1.6%, water: 78.4 percent.

The preparation method of the polyaluminium sulfate solution for the alkali-free liquid accelerator comprises the following steps:

firstly, 784 kg of water is added into a reaction kettle, the temperature is raised to 60 ℃, 200 kg of aluminum sulfate octadecahydrate is added under stirring, and after the dissolution is finished, Zn (OH) is added in batches according to the principle of first-speed and second-speed₂And (3) 16 kg of solid, controlling the reaction temperature at 75-80 ℃, continuing to react for 60 min after the addition is finished, cooling after the solution is clarified, and discharging to obtain the polyaluminium sulfate solution for the alkali-free liquid accelerator.

Comparative example 1:

the addition proportions of the raw materials used in this comparative example were: aluminum sulfate octadecahydrate: 28%, calcium hydroxide: 3.1%, water: 68.9 percent.

The preparation method of the polyaluminium sulfate solution for the alkali-free liquid accelerator of the comparative example comprises the following steps:

689 kg of water is added into a reaction kettle, the temperature is raised to 60 ℃, 280 kg of aluminum sulfate octadecahydrate is added under stirring, and Ca (OH) is added into the mixture in batches according to the principle of first-speed and second-speed after the dissolution is finished₂And (3) 31 kg of solid, controlling the reaction temperature at 70-80 ℃, continuing the reaction for 40min after the addition, filtering to remove precipitates, cooling the filtrate, and discharging.

The detection method and the result are as follows:

after the reaction of the above examples and comparative examples is completed, the product is cooled to room temperature, the alkalization degree of the polyaluminium sulfate product is tested, the residual amount of the waste residue is determined by adopting a drying method after filtration, and the storage stability and the mortar strength at room temperature are tested by adopting a method of GB/T35159 and 2017 accelerating agent for sprayed concrete, wherein the specific test results are shown in the following table 1:

table 1: in the examples, the alkalinization degree of polyaluminium sulfate, the precipitation amount and the stabilization time of waste slag and the strength of 1d mortar

As shown in the test results in Table 1, compared with comparative example 1, the invention selects medium-strong alkali, weak alkali and alkali carbonate thereof as alkalizing agents, the alkalization degree of the prepared polyaluminium sulfate can be regulated and controlled according to actual needs, no waste residue is discharged at all, the obtained polyaluminium sulfate has longer stable period, the generated soluble magnesium sulfate, copper sulfate and zinc sulfate have certain promotion effect on the early strength of the mortar, and the polyaluminium sulfate can be used as a main coagulant component to meet the production needs of alkali-free liquid accelerators and has good application prospect.

Example 5:

the invention relates to an alkali-free liquid accelerator, which is mainly prepared from polyaluminium sulfate prepared in example 1The stabilizing agent comprises 3 percent of silica sol (with the concentration of 20 g/L), 5 percent of calcium-based montmorillonite dispersion (with the mass concentration of 33 percent) and 0.3 percent of auxiliary coagulant triethanolamine, wherein the silica sol is generated after TEOS is hydrolyzed under acidic conditions, and the adding concentration of TEOS in the TEOS hydrolysis process is 0.36 mol.L^-1The hydrolysis temperature is 60 ℃, the hydrolysis time is 30min, and the addition amount of sulfuric acid is 4 percent of the mass of TEOS.

Comparative example 2:

the alkali-free accelerator of this comparative example is different from example 5 in that polyaluminium sulfate is replaced with polyaluminium sulfate prepared in comparative example 1, and the content of other raw materials is the same as example 5, specifically, the alkali-free liquid accelerator of this comparative example mainly comprises polyaluminium sulfate solution prepared in comparative example 1, stabilizer and accelerator triethanolamine, wherein the addition amount of silica sol in the stabilizer is 3%, the addition amount of calcium montmorillonite dispersion is 5%, and the addition amount of accelerator triethanolamine is 0.3%, wherein the silica sol is generated after TEOS is hydrolyzed under acidic condition, and the addition concentration of TEOS in the TEOS hydrolysis process is 0.36 mol.L^-1The hydrolysis temperature is 60 ℃, the hydrolysis time is 30min, and the addition amount of the acid catalyst sulfuric acid is 4 percent of the mass of TEOS.

Example 6:

an alkali-free liquid accelerator of the present invention is composed of polyaluminium sulfate solution prepared in example 1, a stabilizer, and an auxiliary accelerator polyphosphoric acid, wherein the amount of silica sol (concentration 20 g/L) added to the stabilizer is 3%, the amount of calcium montmorillonite dispersion added is 5% (mass concentration 33%), the amount of auxiliary accelerator polyphosphoric acid added is 2%, wherein the silica sol is generated after TEOS is hydrolyzed under acidic condition, and the TEOS addition concentration during TEOS hydrolysis is 0.36 mol.L^-1The hydrolysis temperature is 60 ℃, the hydrolysis time is 30min, and the addition amount of sulfuric acid is 4 percent of the mass of TEOS.

The main properties of the alkali-free liquid accelerators prepared in examples 5 and 6 and comparative example are shown in Table 2.

Table 2: comparison of Main Properties of alkali-free liquid Accelerator prepared in examples and comparative examples

As can be seen from the experimental results shown in Table 2, the use of polyaluminium sulfate prepared according to the present invention (as in example 1) and the alkali-free liquid accelerator compounded with silica sol, calcium-based montmorillonite, triethanolamine as an accelerator or polyphosphoric acid (examples 5 and 6) can improve the stabilization period of the liquid accelerator and further enhance the early strength of the concrete mortar. Compared with comparative example 2 which uses polyaluminium sulfate prepared in comparative example 1 and is also compounded, the compounded alkali-free liquid accelerator prepared by the invention also has the advantage of shortening the initial setting time and the final setting time of cement paste.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.