High concentration milk of lime suspension and method for its preparation

Abstract

The present application relates to the field of environmental protection industry, and particularly relates to a high-concentration lime milk suspension and a preparation method thereof, which comprises water, quicklime, lime-based polycarboxylic acid water reducing agent and suspending agent. The high-concentration lime milk suspension is prepared by specific raw material proportioning and process, and has good flowability, can be pumped and metered, has good stability, small stratification amount, is very convenient to transport and use, has high calcium oxide content, which can reach more than 45%, and has small usage amount for treating acid wastewater and waste gas. The high-concentration lime milk suspension and the preparation method thereof solve the technical problem of low concentration of calcium-based substances in the calcium-based liquid caustic suspension prepared by the existing method.

Description

Technical Field

[0001] This invention relates to the environmental protection industry, specifically to a high-concentration lime slurry suspension and its preparation method. Background Technology

[0002] Wastewater and exhaust gases discharged from chemical plants, electroplating plants, coal processing plants, etc., need to be neutralized to neutral with alkali before proceeding to the next step of treatment. Currently, commonly used acid neutralizing agents for water treatment include caustic soda and lime. Caustic soda has a fast reaction speed and produces few byproducts, but it is highly corrosive and has a high cost. Lime is inexpensive and has a low treatment cost, but it has low solubility in water and requires a large amount.

[0003] Lime as a treatment agent is divided into quicklime and hydrated lime. Quicklime is not convenient to transport and feed, has a slow reaction rate, and is not convenient to treat waste gas. Hydrated lime is generally quicklime that has been slaked with water to form a paste with a calcium oxide content of 20%-30%. Its calcium oxide content is low, and it is a paste, which is inconvenient to transport, use, and feed metering.

[0004] To address the above problems, this invention develops a high-concentration lime slurry suspension that has good fluidity, can be metered with a pump, is easy to use, has a calcium oxide content of over 45%, exhibits minimal stratification after one month of storage, is convenient to transport, and is safe to use.

[0005] Patent CN116282257A discloses a nanoscale calcium-based active composite alkali and its preparation method. This patent also similarly prepares a calcium-based (calcium hydroxide / calcium oxide) liquid alkali suspension, whose main components are also calcium hydroxide / calcium oxide. It can be applied to the defluorination treatment of fluoride-containing wastewater, the dephosphorization treatment of phosphorus-containing wastewater, flue gas desulfurization treatment, and the preparation of feed-grade dicalcium phosphate. However, its effective calcium-based content is limited to a maximum of 25%. This invention, through the synthesis of a specific lime-based polycarboxylate superplasticizer and a special preparation method, can achieve a calcium oxide content of 45%. This can reduce the dosage and transportation costs. Polycarboxylate superplasticizers are currently mainly used in cement-based concrete. The main chemical components of cement are calcium oxide, silicon dioxide, ferric oxide, and aluminum oxide. The main chemical component of quicklime is calcium oxide. Since cement contains calcium oxide, cement-based polycarboxylate superplasticizers can play a water-reducing role in lime. However, since the composition of these two substances is quite different, a special superplasticizer needs to be formulated for calcium oxide. This superplasticizer needs to have characteristics such as high water reduction rate, low bleeding rate, and non-segregation. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a high-concentration lime slurry suspension. This invention is based on improvements to existing processes and, combined with practical applications, employs a special process by adding a specially formulated polycarboxylate superplasticizer and suspending agent to provide a high-concentration lime slurry suspension and its preparation method. This solves the technical problem of low concentration of calcium-based substances in existing methods for preparing calcium-based alkaline suspensions.

[0007] The present invention provides a high-concentration lime slurry suspension, the raw materials of which, by mass percentage, comprise the following components: 40-60 parts water, 40-60 parts quicklime, 0.5-1 parts lime-based polycarboxylate superplasticizer, and 1-2 parts suspending agent.

[0008] The present invention provides a method for preparing a high-concentration lime slurry suspension, comprising the following preparation steps:

[0009] Step 1: Dissolve 30-40 parts quicklime in 50-60 parts water to form a paste-like lime slurry, then add 0.3-0.5 parts of the prepared lime-based polycarboxylate superplasticizer to form a lime slurry suspension;

[0010] Step 2: Add 10-20 parts of quicklime to the lime milk suspension obtained in Step 1, continue the reaction to form a paste-like lime milk, and then add 0.3-0.5 parts of the prepared lime-based polycarboxylate superplasticizer to form a lime milk suspension;

[0011] Step 3: Add 1-2 parts of the prepared suspending agent to the lime milk suspension obtained in step 2, while stirring, to obtain a high-concentration lime milk suspension.

[0012] Preferably, a lime-based polycarboxylate superplasticizer used in a method for preparing a high-concentration lime slurry suspension includes the following preparation steps:

[0013] Step 1: Select the following raw materials by mass percentage: 60-70 parts water, 30-40 parts ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000, 0.5-1 part fumaric acid, 1-2 parts acrylamide, 0.1-0.2 parts hydrogen peroxide, 0.05-0.1 parts vitamin C, and 0.5-1 parts sodium hypophosphite.

[0014] Step 2: Dissolve acrylamide, vitamin C and sodium hypophosphite in water respectively to obtain acrylamide solution, vitamin C solution and sodium hypophosphite solution respectively;

[0015] Step 3: Dissolve and stir ethylene glycol monovinyl polyethylene glycol ether and fumaric acid to obtain a uniform base solution, then add hydrogen peroxide and stir to obtain a uniform solution.

[0016] Step four: In the homogeneous solution obtained in step three, acrylamide solution, vitamin C solution, and sodium hypophosphite solution are added dropwise. The dropping temperature is set to 15℃-25℃ and the dropping rate is set to 1g / min. After the addition is complete, the solution is aged for 1 hour, and then water is added until the solution concentration is 40%, thus obtaining a lime-based polycarboxylate superplasticizer.

[0017] Preferably, in step three of the preparation of a lime-based polycarboxylate superplasticizer, the concentration of the base solution is 50-60% and the concentration of hydrogen peroxide is 27.5%; in step four of the preparation of a lime-based polycarboxylate superplasticizer, the acrylamide solution is added over 50 minutes, and the vitamin C solution and sodium hypophosphite solution are added over 60 minutes.

[0018] Preferably, a suspending agent used in a method for preparing a high-concentration lime milk suspension is prepared by adding 10% hydrated magnesium silicate under high-speed shear stirring and then shearing at high speed for 30 minutes to obtain a paste-like hydrated magnesium silicate suspension.

[0019] Beneficial effects: The present invention provides a high-concentration lime slurry suspension and its preparation method. By specially preparing a polycarboxylate superplasticizer suitable for lime with high water reduction rate and low bleeding rate, and then adding quicklime in two stages, a lime slurry suspension with high fluidity and high calcium oxide content is obtained. Finally, a suspending agent is added to increase its stability, so that the suspension does not separate into layers for a long time.

[0020] The present invention has the following advantages over similar products: the lime slurry suspension of the present invention has good fluidity and can be pumped and metered using a water pump; the lime slurry suspension of the present invention has a high calcium oxide content, reaching more than 45%, and requires a small amount to treat acidic wastewater and waste gas; the lime slurry suspension of the present invention has good stability and small stratification. Detailed Implementation

[0021] To make the technical means, creative features, objectives and effects of this invention easier to understand, the technical solutions in the specific embodiments of this invention are described clearly and completely below to further illustrate this invention. Obviously, the specific embodiments described are only a part of the embodiments of this invention, and not all of them.

[0022] Example

[0023] First, prepare four types of lime-based polycarboxylate superplasticizers according to the formulas in Table 1.

[0024] Table 1 shows the preparation formula for water-reducing agents:

[0025]

[0026] The preparation steps of water-reducing agent sample No. 1 are as follows: 375g of ethylene glycol monovinyl polyethylene glycol ether, 0g of fumaric acid, 300g of water and 2.5g of hydrogen peroxide are added to a four-necked flask and stirred to dissolve, resulting in a homogeneous solution. Solution No. 1 (20g of acrylamide dissolved in 30g of water) and solution No. 2 (0.5g of vitamin C and 5g of sodium hypophosphite dissolved in 55g of water) are prepared separately. At a dropping temperature of 20±5℃ and a dropping rate of 1g / min, solutions No. 1 and No. 2 are added simultaneously. After the addition is complete, the mixture is aged for 1 hour. Finally, 212g of water is added to obtain a lime-based polycarboxylate water-reducing agent with a mass concentration of approximately 40%.

[0027] The preparation steps of water-reducing agent sample No. 2 are as follows: 375g of ethylene glycol monovinyl polyethylene glycol ether, 5g of fumaric acid, 300g of water and 2.5g of hydrogen peroxide are added to a four-necked flask and stirred to dissolve, resulting in a homogeneous bottom solution. Solution No. 1 (15g of acrylamide dissolved in 35g of water) and solution No. 2 (0.5g of vitamin C and 5g of sodium hypophosphite dissolved in 55g of water) are prepared separately. At a dropping temperature of 20±5℃ and a dropping rate of 1g / min, solutions No. 1 and No. 2 are added simultaneously. After the addition is complete, the mixture is aged for 1 hour. Finally, 212g of water is added to obtain a lime-based polycarboxylate water-reducing agent with a mass concentration of approximately 40%.

[0028] The preparation steps of water-reducing agent sample No. 3 are as follows: 375g of ethylene glycol monovinyl polyethylene glycol ether, 10g of fumaric acid, 300g of water and 2.5g of hydrogen peroxide are added to a four-necked flask and stirred to dissolve, resulting in a homogeneous bottom solution. Solution No. 1 (10g of acrylamide dissolved in 40g of water) and solution No. 2 (0.5g of vitamin C and 5g of sodium hypophosphite dissolved in 55g of water) are prepared separately. At a dropping temperature of 20±5℃ and a dropping rate of 1g / min, solutions No. 1 and No. 2 are added simultaneously. After the addition is complete, the mixture is aged for 1 hour. Finally, 212g of water is added to obtain a lime-based polycarboxylate water-reducing agent with a mass concentration of approximately 40%.

[0029] The preparation steps of water-reducing agent sample No. 4 are as follows: 375g of ethylene glycol monovinyl polyethylene glycol ether, 20g of fumaric acid, 300g of water and 2.5g of hydrogen peroxide are added to a four-necked flask and stirred to dissolve, resulting in a homogeneous bottom solution. Solution No. 1 (0g of acrylamide dissolved in 50g of water) and solution No. 2 (0.5g of vitamin C and 5g of sodium hypophosphite dissolved in 55g of water) are prepared separately. At a dropping temperature of 20±5℃ and a dropping rate of 1g / min, solutions No. 1 and No. 2 are added simultaneously. After the addition is complete, the mixture is aged for 1 hour. Finally, 212g of water is added to obtain a lime-based polycarboxylate water-reducing agent with a mass concentration of approximately 40%.

[0030] During the preparation of the four water-reducing agent samples, the concentration of the base solution was 50-60%, the concentration of hydrogen peroxide used was 27.5%, the dripping time of solution No. 1 was 50 minutes, and the dripping time of solution No. 2 was 60 minutes.

[0031] Next, the preparation of the suspending agent will be carried out.

[0032] The preparation steps of the suspension are as follows: 100g of hydrated magnesium silicate powder is added to 900g of water, and the mixture is stirred for 30 minutes using a high-speed disperser at a speed of 3000 rpm to obtain a paste-like suspension with a mass concentration of 10%.

[0033] Then, five types of high-concentration lime milk suspensions were prepared.

[0034] The preparation steps of high-concentration lime milk suspension No. 1 are as follows: First, 30g of quicklime is dissolved in 55g of water to form a paste-like lime milk. Then, 0.3g of water-reducing agent No. 1 sample is added to form a lime milk suspension. Next, 15g of quicklime is added, and the reaction continues to form a paste-like lime milk. Then, 0.3g of water-reducing agent No. 1 sample is added to form a lime milk suspension. Finally, 1g of the prepared suspending agent is added while stirring to obtain a high-concentration lime milk suspension.

[0035] The preparation steps of high-concentration lime milk suspension No. 2 are as follows: First, 30g of quicklime is dissolved in 55g of water to form a paste-like lime milk. Then, 0.3g of water-reducing agent No. 2 sample is added to form a lime milk suspension. Next, 15g of quicklime is added, and the reaction continues to form a paste-like lime milk. Then, 0.3g of water-reducing agent No. 2 sample is added to form a lime milk suspension. Finally, 1g of the prepared suspending agent is added while stirring to obtain a high-concentration lime milk suspension.

[0036] The preparation steps of high-concentration lime milk suspension No. 3 are as follows: First, 30g of quicklime is dissolved in 55g of water to form a paste-like lime milk. Then, 0.3g of water-reducing agent No. 3 sample is added to form a lime milk suspension. Next, 15g of quicklime is added, and the reaction continues to form a paste-like lime milk. Then, 0.3g of water-reducing agent No. 3 sample is added to form a lime milk suspension. Finally, 1g of the prepared suspending agent is added while stirring to obtain a high-concentration lime milk suspension.

[0037] The preparation steps of high-concentration lime milk suspension No. 4 are as follows: First, 30g of quicklime is dissolved in 55g of water to form a paste-like lime milk. Then, 0.3g of water-reducing agent No. 4 sample is added to form a lime milk suspension. Next, 15g of quicklime is added, and the reaction continues to form a paste-like lime milk. Then, 0.3g of water-reducing agent No. 4 sample is added to form a lime milk suspension. Finally, 1g of the prepared suspending agent is added while stirring to obtain a high-concentration lime milk suspension.

[0038] The preparation steps of high-concentration lime milk suspension No. 5 are as follows: First, 30g of quicklime is dissolved in 55g of water to form a paste-like lime milk. Then, 0.3g of water-reducing agent No. 3 is added to form a lime milk suspension. Next, 15g of quicklime is added, and the reaction continues to form a paste-like lime milk. Then, 0.3g of water-reducing agent No. 3 is added to form a lime milk suspension. Finally, 0g of the prepared suspending agent is added while stirring to obtain a high-concentration lime milk suspension.

[0039] Application Example 1

[0040] To test the flowability, a Ford-4 viscosity cup was used. The cup was filled with lime slurry suspension, and the flow time was measured. The shorter the time, the better the flowability. The experimental results are shown in Table 2.

[0041] Table 2 shows the liquidity test data for application examples:

[0042]

[0043] Application Example 2

[0044] To test stability, 100 mL of lime milk suspension was poured into a 100 mL graduated cylinder with a cap, and the separation was tested after 30 days. The greater the separation height, the worse the stability. The experimental results are shown in Table 3.

[0045] Table 3 shows the stability test data for the application examples:

[0046]

[0047] Since water-reducing agents are concrete admixtures that reduce the amount of mixing water while maintaining a relatively constant slump in concrete, they disperse cement particles after being added to the concrete mixture. Therefore, water-reducing agents can improve the workability of the concrete, reduce the unit water consumption, and improve the fluidity of the concrete mixture. In other words, the better the stratification fluidity of the lime slurry suspension with added water-reducing agent, the higher the water reduction rate of the water-reducing agent. As shown in Table 2, samples No. 3 and No. 4 of water-reducing agents have higher water reduction rates. As shown in Table 3, water-reducing agents with introduced amide groups have relatively better stability. As shown in Table 3, suspending agents play a crucial role in the stability of high-concentration lime slurry suspensions. Through application examples 1 and 2, it can be found that sample No. 3 of water-reducing agent has the best comprehensive performance, with both a high water reduction rate and good stability.

[0048] Because the high-concentration lime slurry suspension prepared by this invention has a high effective calcium-based substance, namely calcium oxide content, reaching over 45%, while the effective calcium-based substance content of a calcium-based (calcium hydroxide / calcium oxide) liquid alkali suspension prepared by a nano-scale calcium-based active composite alkali and its preparation method disclosed in patent CN116282257A can only reach a maximum of 25%, and the high-concentration lime slurry suspension prepared by this invention also possesses similar alkali neutralization properties to the aforementioned calcium-based (calcium hydroxide / calcium oxide) liquid alkali suspension, therefore the high-concentration lime slurry suspension prepared by this invention... The lime milk suspension has a highly efficient function in treating acidic wastewater and exhaust gas. In addition, the effective calcium-based substance content of the high-concentration lime milk suspension prepared by this invention is much higher than that of the aforementioned calcium-based (calcium hydroxide / calcium oxide) liquid alkali suspension. This effective calcium-based substance is the key substance for alkali neutralization treatment of acidic wastewater and exhaust gas. Therefore, the high-concentration lime milk suspension prepared by this invention can achieve similar or even smaller usage results in alkali neutralization treatment of acidic wastewater and exhaust gas compared to the aforementioned calcium-based (calcium hydroxide / calcium oxide) liquid alkali suspension.

[0049] Furthermore, it should be understood that although this specification describes various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-concentration lime slurry suspension, characterized in that, Its raw materials, calculated by weight, include the following components: 40-60 parts water, 40-60 parts quicklime, 0.5-1 parts lime-based polycarboxylate superplasticizer, and 1-2 parts suspending agent; The preparation steps of the lime-based polycarboxylate superplasticizer are as follows: Step 1: Select the following raw materials by weight: 60-70 parts water, 30-40 parts ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000, 0.5-1 part fumaric acid, 1-2 parts acrylamide, 0.1-0.2 parts hydrogen peroxide, 0.05-0.1 parts vitamin C, and 0.5-1 parts sodium hypophosphite. Step 2: Dissolve acrylamide, vitamin C and sodium hypophosphite in water respectively to obtain acrylamide solution, vitamin C solution and sodium hypophosphite solution respectively; Step 3: Dissolve and stir ethylene glycol monovinyl polyethylene glycol ether and fumaric acid to obtain a uniform base solution, then add hydrogen peroxide and stir to obtain a uniform solution. Step four: Add acrylamide solution, vitamin C solution, and sodium hypophosphite solution dropwise to the homogeneous solution obtained in step three. Set the dropwise temperature to 15℃-25℃ and the dropwise rate to 1g / min. After the dropwise addition is complete, age the solution for 1 hour, and then add water until the solution concentration is 40% to obtain lime-based polycarboxylate superplasticizer.

2. The high-concentration lime slurry suspension according to claim 1, characterized in that, In step three of the preparation steps of the lime-based polycarboxylate superplasticizer, the concentration of the base solution is 50-60%, and the concentration of hydrogen peroxide is 27.5%; in step four of the preparation steps of the lime-based polycarboxylate superplasticizer, the acrylamide solution is added over a period of 50 minutes, and the vitamin C solution and sodium hypophosphite solution are added over a period of 60 minutes.

3. A method for preparing a high-concentration lime slurry suspension, the method being used to prepare the high-concentration lime slurry suspension according to claim 1, characterized in that, It includes the following steps: Step 1: Dissolve 30-40 parts quicklime in 50-60 parts water to form a paste-like lime slurry, then add 0.3-0.5 parts of the prepared lime-based polycarboxylate superplasticizer to form a lime slurry suspension; Step 2: Add 10-20 parts of quicklime to the lime milk suspension obtained in Step 1, continue the reaction to form a paste-like lime milk, and then add 0.3-0.5 parts of the prepared lime-based polycarboxylate superplasticizer to form a lime milk suspension; Step 3: Add 1-2 parts of the prepared suspending agent to the lime milk suspension obtained in step 2, while stirring, to obtain a high-concentration lime milk suspension.

4. The method for preparing a high-concentration lime slurry suspension according to claim 3, characterized in that, The preparation steps of the suspension are as follows: a paste-like hydrated magnesium silicate suspension is prepared by high-speed shearing of 10% concentration magnesium silicate for 30 minutes.

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