A preparation process of scale inhibitor

Abstract

The present invention relates to the technical field of scale removal, and discloses a preparation process of a scale inhibitor, which is as follows: Step 1, under inert conditions, ethanolamine, toluene, phosphinoethane, and a catalyst are added to a first reactor respectively, and a heating reaction is carried out. After the reaction is completed, sedimentation separation is carried out, and the bottom flow is sent to a retention tank as an intermediate product 1 for standby use, and the overflow is returned to the first reactor; Step 2, the intermediate product 1 and a hydrophobic agent are sent to a second reactor, and a heating reaction is carried out. After the reaction is completed, the reaction is sent to a cooler to be cooled to room temperature to obtain an intermediate product 2; Step 3, the intermediate product 2 and a coupling agent are sent to a third reactor, and a heating reaction is carried out. After the reaction is completed, an intermediate product 3 is obtained; Step 4, the intermediate product 3 is sent to a dissolution tank, and a dissolving solution is added to the intermediate product 3 to dissolve it to obtain the final product. In the production process of alumina, a scale inhibitor is added to the solution to prevent sodalite from precipitating during the production process.

Description

Technical Field

[0001] The invention belongs to the technical field of scale removal, and in particular relates to a preparation process of a scale inhibitor. Background Art

[0002] The alumina industry uses concentrated sodium hydroxide to dissolve the aluminum oxide in bauxite and convert it into sodium aluminate. The aluminum hydroxide is then reprecipitated through dilution and the addition of aluminum hydroxide seed crystals. The remaining sodium aluminate solution is evaporated to remove excess water and reused to process the next batch of bauxite, achieving continuous production. The Bayer process primarily involves ore crushing, homogenization, and wet grinding, high-temperature and high-pressure dissolution, red mud separation and washing, leaf filtration, seed decomposition, mother liquor evaporation, and aluminum hydroxide roasting.

[0003] All bauxites contain silica, but the concentration varies greatly. Silica occurs as silicates, primarily clay minerals, and dissolves rapidly under conventional Bayer process dissolution conditions. Subsequently, most silica precipitates as sodium aluminosilicate (sodalite) or DSP (desiliconization product). However, precipitation is slower than dissolution, resulting in a constant supersaturation of silica in the Bayer process liquor. The actual silica concentration is always higher than the equilibrium value, meaning the solution is always supersaturated with silica. The supersaturation of silica is even greater in the mother liquor after seed decomposition. Although the supersaturation of silica increases during seed decomposition, very little silica precipitates with aluminum hydroxide because the temperature is low. When the mother liquor evaporates and new bauxite is dissolved, the solution containing the precipitated aluminum oxide is reheated, and silica precipitates as sodalite, with the rate increasing significantly with increasing temperature. While increasing temperature slightly increases silica solubility, its precipitation rate increases due to faster kinetics.

[0004] When the solution is heated, sodalite precipitates as crusts on the inner surfaces of heat exchange tubes, causing heat transfer losses and requiring frequent shutdowns for cleaning. Although the amount of silica precipitated as sodalite within the heat exchanger is less than 1% of the solution, the large volume of the solution allows sodalite crusts to form rapidly. This sodalite easily forms as scale on the walls of equipment and devices used (such as pipes, digesters, pumps, and heat exchangers). The presence of this material is detrimental to alumina production operations, as the formation of scale causes processing losses. Furthermore, scale deposits on equipment and devices (such as heat exchanger digesters and pipe walls) significantly reduce equipment efficiency because the flow of materials through the pipes is severely obstructed, reducing heat transfer to the material flow. Therefore, removing scale is key to energy conservation and cost reduction in alumina refineries. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation process of a scale inhibitor to solve at least one of the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0007] In some embodiments of the present application, a process for preparing a scale inhibitor is provided, wherein the scale inhibitor comprises ingredients including: ethanolamine, toluene, phosphinoethane, a catalyst, a hydrophobic agent, and a coupling agent.

[0008] Preferably, in a preferred embodiment of the above-mentioned preparation process of a scale inhibitor, the preparation process is as follows:

[0009] Step 1: Under inert conditions, ethanolamine, toluene, phosphinoethane, and a catalyst are added to a first reactor, respectively, and heated to react. After the reaction is completed, sedimentation separation is performed, and the bottom flow is sent to a retention tank as an intermediate product for standby use, and the overflow is returned to the first reactor;

[0010] Step 2: feeding the intermediate product 1 and the hydrophobic agent into a second reactor, heating the reaction under inert conditions, and after the reaction is completed, feeding the reaction mixture into a cooler to cool to room temperature to obtain the intermediate product 2;

[0011] Step 3: feeding the intermediate product 2 and the coupling agent into a third reactor for heating reaction to obtain the intermediate product 3 after the reaction is completed;

[0012] Step 4: Send the intermediate product 3 into the dissolution tank, add the dissolving liquid to dissolve the intermediate product 3, and package it after the dissolution is completed to obtain the final product.

[0013] Preferably, in a preferred embodiment of the above-mentioned process for preparing a scale inhibitor, the reaction temperature in step 1 is 100-200° C., and the reaction time is 20 hours.

[0014] Preferably, in a preferred embodiment of the above-mentioned process for preparing a scale inhibitor, the heating temperature in the step 2 is 40-100° C., and the reaction time is 2 hours.

[0015] Preferably, in a preferred embodiment of the above-mentioned process for preparing a scale inhibitor, the heating temperature in step 3 is 20-40° C., and the reaction time is 20-60 minutes.

[0016] Preferably, in a preferred embodiment of the above-mentioned scale inhibitor preparation process, the dissolving liquid in step 4 is alkaline water.

[0017] Preferably, in a preferred embodiment of the above-mentioned process for preparing a scale inhibitor, the scale inhibitor preparation device is as follows, comprising:

[0018] The first reactor is provided with a stirring paddle, which can stir the ethanolamine, toluene, phosphinoethane and catalyst during the heating reaction;

[0019] A settling tank is connected to the first reactor. After the reaction of the ethanolamine, toluene, phosphinoethane, and catalyst is completed, the ethanolamine, toluene, phosphinoethane, and catalyst enter the settling tank for sedimentation and separation. The bottom flow after sedimentation and separation is used as the intermediate product 1, and the overflow material is returned to the first reactor.

[0020] A retention tank is connected to the sedimentation tank, and the intermediate product formed in the sedimentation tank is temporarily stored in the retention tank for standby use;

[0021] A second reactor is connected to the retention tank, wherein the intermediate product 1 and the hydrophobic agent are added to the second reactor for heating reaction, and a stirring paddle is provided in the second reactor to stir the intermediate product 1 and the hydrophobic agent during the reaction;

[0022] A cooler is connected to the second reactor, wherein the cooling medium of the cooler is 5°C cold water. After the intermediate product 1 and the hydrophobic agent are reacted in the second reactor, they are cooled in the cooler to generate the intermediate product 2;

[0023] A third reactor is connected to the cooler, wherein the intermediate product 2 and the coupling agent are heated and reacted in the second reactor to obtain the intermediate product 3;

[0024] The dissolving tank is connected to the third reactor, and the intermediate product 3 enters the dissolving tank and is dissolved in alkaline water to obtain the final product.

[0025] Preferably, in a preferred embodiment of the above-mentioned scale inhibitor preparation process, the first reactor and the second reactor are made of stainless steel material that is resistant to strong acids and alkalis.

[0026] The above technical solution shows that, compared with the prior art, the present invention has the following beneficial effects: by adding a scale inhibitor to the solution during the alumina production process, sodalite is prevented from precipitating during the production process, thereby inhibiting the formation of scabs and preventing sodalite from depositing as scale on the walls of the devices and equipment used (such as pipes, cooking tanks, pumps, heat exchangers, etc.), which affects work efficiency and causes processing losses, thus preventing production downtime, reducing heat transfer losses, and saving energy. By rationally matching the raw materials and their interaction during use, the process of silicon dioxide forming sodalite is prevented. The present invention is highly safe and environmentally friendly, has low production costs, is non-toxic, has a good scale inhibition effect, does not cause environmental pollution, and greatly reduces subsequent processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0028] Figure 1 This is a schematic diagram of feeding the scale inhibitor preparation device according to an embodiment of the present invention;

[0029] In the picture:

[0030] a1, ethanolamine; a2, toluene; a3, phosphinoethane; a4, catalyst; a5, hydrophobic agent; a6, coupling agent;

[0031] b1, first reactor; b2, sedimentation tank; b3, retention tank; b4, second reactor; b5, cooler; b6, third reactor; b7, dissolution tank. DETAILED DESCRIPTION

[0032] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0033] In the description of this application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0034] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0035] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0036] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below with reference to the accompanying drawings.

[0037] The present application provides a process for preparing a scale inhibitor, wherein the scale inhibitor comprises: ethanolamine a1, toluene a2, phosphinoethane a3, catalyst a4, hydrophobic agent a5, and coupling agent a6.

[0038] In order to further optimize the above technical solution, the preparation process is as follows:

[0039] Step 1: Under inert conditions, ethanolamine a1, toluene a2, phosphinoethane a3, and catalyst a4 are added to the first reactor b1 for heating and reaction. After the reaction is completed, sedimentation and separation are performed. The bottom flow is sent to the retention tank b3 as the intermediate product for standby use, and the overflow is returned to the first reactor b1.

[0040] Step 2: The intermediate product 1 and the hydrophobic agent a5 are fed into a second reactor b4 and heated under inert conditions for reaction. After the reaction is completed, the mixture is fed into a cooler b5 and cooled to room temperature to obtain the intermediate product 2.

[0041] Step 3: feeding the intermediate product 2 and the coupling agent a6 into a third reactor b6 for heating reaction to obtain the intermediate product 3 after the reaction is completed;

[0042] Step 4: send the intermediate product 3 into the dissolution tank b7, add the dissolving liquid to dissolve the intermediate product 3, and package it after the dissolution is completed to obtain the final product.

[0043] To further optimize the above technical solution, the reaction temperature in step 1 is 100-200°C and the reaction time is 20 hours.

[0044] To further optimize the above technical solution, the heating temperature in step 2 is 40-100°C and the reaction time is 2 hours.

[0045] To further optimize the above technical solution, the heating temperature in step 3 is 20-40°C and the reaction time is 20-60 minutes.

[0046] To further optimize the above technical solution, the dissolving liquid in step 4 is alkaline water.

[0047] See Figure 1 As shown, in order to further optimize the above technical solution, the scale inhibitor preparation device is as follows, including:

[0048] The first reactor b1 is provided with a stirring paddle, which can stir the ethanolamine, toluene, phosphinoethane and catalyst during the heating reaction;

[0049] The sedimentation tank b2 is connected to the first reactor. After the reaction of the ethanolamine a1, toluene a2, phosphinoethane a3, and catalyst a4 is completed, the sedimentation tank b7 is used for sedimentation separation. The bottom flow after sedimentation separation is used as the intermediate product 1, and the overflow is returned to the first reactor b1.

[0050] The retention tank b3 is connected to the sedimentation tank b2, and the intermediate product formed in the sedimentation tank b2 is temporarily stored in the retention tank b3 for standby use;

[0051] A second reactor b4 is connected to the retention tank b3, and the intermediate product 1 and the hydrophobic agent a5 are added to the second reactor b4 for heating and reacting. The second reactor is provided with a stirring paddle to stir the intermediate product 1 and the hydrophobic agent a5 during the reaction;

[0052] Cooler b5 is connected to the second reactor b4. The cooling medium of cooler b5 is 5°C cold water. After the reaction of the intermediate product 1 and the hydrophobic agent a5 in the second reactor b4 is completed, the intermediate product 1 enters the cooler b5 for cooling to generate the intermediate product 2.

[0053] The third reactor b6 is connected to the cooler b5, and the intermediate product 2 and the coupling agent a6 are heated and reacted in the second reactor b4 to obtain the intermediate product 3;

[0054] The dissolving tank b7 is connected to the third reactor b6. The intermediate product 3 enters the dissolving tank b7 and is dissolved in alkaline water to obtain the final product.

[0055] It should be noted that the first reactor b1 and the second reactor b4 are of electric heating type, steam heating type, jacketed type, and the stirring blades can be inclined blade type, anchor type, frame type, propeller type, and single (double) screw type;

[0056] The sedimentation tank b2 can be a gravity sedimentation tank or a high-speed centrifugal sedimentation machine;

[0057] Cooler b5 is a shell and tube type, plate type, or spiral type heat exchanger, preferably a spiral type heat exchanger;

[0058] The third reactor b6 is a kettle type, tubular type, or screw type reactor, preferably a screw type reactor.

[0059] In order to further optimize the above technical solution, the first reactor b1 and the second reactor b4 are made of stainless steel that is resistant to strong acids and alkalis.

[0060] Specifically, the first reactor b1 and the second reactor b4 are prevented from being corroded during the heating reaction of ethanolamine a1, toluene a2, phosphinoethane a3, catalyst a4, and hydrophobic agent a5.

[0061] During the alumina production process, scale inhibitors are added to the solution to prevent sodalite from precipitating during the production process, thereby inhibiting the formation of scale, preventing production downtime and saving energy.

[0062] Example 1

[0063] Step 1: Under inert conditions, ethanolamine a1, toluene a2, phosphinoethane a3, and catalyst a4 are added to the first reactor b1 for heating reaction at a temperature of 100°C for 20 hours. After the reaction is completed, the mixture enters the settling tank b2 for sedimentation separation. The bottom flow after sedimentation is sent to the retention tank b3 as the intermediate product for standby use, and the overflow returns to the first reactor b1.

[0064] Step 2: The intermediate product 1 and the hydrophobic agent a5 are fed into a second reactor b4 and heated under inert conditions at 40°C for 2 hours. After the reaction is complete, the mixture is fed into a cooler b5 and cooled to room temperature to obtain the intermediate product 2.

[0065] Step 3: The intermediate product 2 and the coupling agent a6 are fed into a third reactor b6 for heating reaction at a temperature of 20° C. for 20 minutes to obtain the intermediate product 3.

[0066] Step 4: Send the intermediate product 3 to the dissolution tank b7, add alkaline water to the intermediate product 3 for dissolution, and package it after dissolution is completed to obtain the final product.

[0067] Example 2

[0068] Step 1: Under inert conditions, ethanolamine a1, toluene a2, phosphinoethane a3, and catalyst a4 are added to the first reactor b1 and heated to react at a temperature of 150°C for 20 hours. After the reaction is completed, the mixture enters the settling tank b2 for sedimentation separation. The bottom flow after sedimentation is sent to the retention tank b3 as the intermediate product for standby use, and the overflow returns to the first reactor b1.

[0069] Step 2: The intermediate product 1 and the hydrophobic agent a5 are fed into a second reactor b4 and heated under inert conditions at 70°C for 2 hours. After the reaction is complete, the mixture is fed into a cooler b5 and cooled to room temperature to obtain the intermediate product 2.

[0070] Step 3: The intermediate product 2 and the coupling agent a6 are fed into a third reactor b6 for heating reaction at a temperature of 30° C. for 40 minutes to obtain the intermediate product 3.

[0071] Step 4: Send the intermediate product 3 to the dissolution tank b7, add alkaline water to the intermediate product 3 for dissolution, and package it after dissolution is completed to obtain the final product.

[0072] Example 3

[0073] Step 1: Under inert conditions, ethanolamine a1, toluene a2, phosphinoethane a3, and catalyst a4 are added to the first reactor b1 and heated to react at a temperature of 200°C for 20 hours. After the reaction is completed, the mixture enters the settling tank b2 for sedimentation separation. The bottom flow after sedimentation is sent to the retention tank b3 as the intermediate product for standby use, and the overflow returns to the first reactor b1.

[0074] Step 2: The intermediate product 1 and the hydrophobic agent a5 are fed into a second reactor b4 and heated under inert conditions at 100°C for 2 hours. After the reaction is complete, the mixture is fed into a cooler b5 and cooled to room temperature to obtain the intermediate product 2.

[0075] Step 3: The intermediate product 2 and the coupling agent a6 are fed into a third reactor b6 for heating reaction at 40°C for 60 minutes to obtain the intermediate product 3.

[0076] Step 4: Send the intermediate product 3 to the dissolution tank b7, add alkaline water to the intermediate product 3 for dissolution, and package it after dissolution is completed to obtain the final product.

[0077] The scale inhibitor prepared in the embodiment was subjected to a scale inhibitor detection experiment, and the experimental process is as follows:

[0078] Solution preparation

[0079] Preparation of sodium aluminate solution: Take a certain amount of Al(OH)3 and NaOH and add them to a beaker. Add an appropriate amount of deionized water and heat on an electric stove until it is clear. After cooling, vacuum filter to obtain the homemade sodium aluminate solution. Its composition is shown in Table 1:

[0080]

[0081] Preparation of sodium silicate solution: Take a certain amount of sodium silicate nonahydrate and add it to a 1L volumetric flask. Dissolve it with deionized water and make up to volume. The SiO2 concentration is 20.0g﹒L -1 of sodium silicate aqueous solution.

[0082] Antiscalant solution: add a certain amount of synthetic antiscalant to a solution with a concentration of 10 g L -1 The NaOH aqueous solution was stirred and dissolved to prepare a 1% scale inhibitor solution.

[0083] Blank test: Add 150ml of sodium aluminate solution and 40.0ml of sodium silicate solution to a 250ml plastic bottle, tighten the cap, stir thoroughly, and then place in a 95°C constant temperature water bath shaker. After 5 minutes, sample and filter the filtrate to determine the SiO2 concentration (C0), which is used as the initial concentration of the supersaturated solution. After a certain period of time, measure the residual silica concentration (C') in the solution.

[0084] Sample test: Take 150ml of sodium aluminate solution and 40.0ml of sodium silicate solution and add them to a 250ml plastic bottle, screw the lid tightly, stir evenly and place in a 95℃ constant temperature water bath oscillator to keep warm and shake. After 5 minutes, add the scale inhibitor solution and test the silica concentration C in the solution after a certain period of time. n .

[0085] Scale inhibition rate η a =(C n -C') / (C0-C'),

[0086] Wherein, C0 is the initial silica concentration of the solution; C' is the silica concentration of the blank solution after incubation; and Cn is the silica concentration of the sample solution after incubation.

[0087] The initial silica concentration of the mixed solution of sodium aluminate solution and sodium silicate solution was measured to be 3.38 g﹒ L -1 After 3h and 6h of heat preservation and oscillation, the residual silica concentrations of the blank and antiscalant added sample solutions were measured respectively, and the scale inhibition rates were calculated. The results are shown in Table 2.

[0088]

[0089] As can be seen from the above table, after adding 30 ppm of the scale inhibitor prepared in the embodiment, the residual silica concentration remains basically unchanged, and the scale inhibition rate after 6 hours is 96.7%. The scale inhibition effect is good and effectively prevents the precipitation and scarring of silica in the form of sodalite, which causes unnecessary heat transfer loss of the equipment.

[0090] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0091] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for preparing a scale inhibitor, characterized in that: The scale inhibitor comprises the following components: ethanolamine, toluene, phosphinoethane, a catalyst, a hydrophobic agent, and a coupling agent; The preparation process is as follows: Step 1: Under inert conditions, ethanolamine, toluene, phosphinoethane, and a catalyst are added to a first reactor, respectively, and heated to react. After the reaction is completed, sedimentation separation is performed, and the bottom flow is sent to a retention tank as an intermediate product for standby use, and the overflow is returned to the first reactor; Step 2: feeding the intermediate product 1 and the hydrophobic agent into a second reactor, heating the reaction under inert conditions, and after the reaction is completed, feeding the reaction mixture into a cooler to cool to room temperature to obtain the intermediate product 2; Step 3: feeding the intermediate product 2 and the coupling agent into a third reactor for heating reaction to obtain the intermediate product 3 after the reaction is completed; Step 4: feeding the intermediate product 3 into a dissolving tank, adding a dissolving liquid to the intermediate product 3 to dissolve it, and packaging it after dissolution is completed to obtain the final product; In the step 1, the reaction temperature is 100-200°C and the reaction time is 20 hours; In step 2, the heating temperature is 40-100°C and the reaction time is 2 hours; In the step 3, the heating temperature is 20-40° C., and the reaction time is 20-60 minutes.

2. The preparation process of a scale inhibitor according to claim 1, characterized in that: The dissolving liquid in the step 4 is alkaline water.

3. The preparation process of a scale inhibitor according to claim 1, characterized in that: The scale inhibitor preparation device is as follows, comprising: The first reactor is provided with a stirring paddle, which can stir the ethanolamine, toluene, phosphinoethane and catalyst during the heating reaction; A settling tank is connected to the first reactor. After the reaction of the ethanolamine, toluene, phosphinoethane, and catalyst is completed, the ethanolamine, toluene, phosphinoethane, and catalyst enter the settling tank for sedimentation and separation. The bottom flow after sedimentation and separation is used as the intermediate product 1, and the overflow material is returned to the first reactor. A retention tank is connected to the sedimentation tank, and the intermediate product formed in the sedimentation tank is temporarily stored in the retention tank for standby use; A second reactor is connected to the retention tank, wherein the intermediate product 1 and the hydrophobic agent are added to the second reactor for heating and reacting. The second reactor is provided with a stirring paddle to stir the intermediate product 1 and the hydrophobic agent during the reaction; A cooler is connected to the second reactor, wherein the cooling medium of the cooler is 5°C cold water. After the intermediate product 1 and the hydrophobic agent are reacted in the second reactor, they are cooled in the cooler to generate the intermediate product 2; A third reactor is connected to the cooler, wherein the intermediate product 2 and the coupling agent are heated and reacted in the second reactor to obtain the intermediate product 3; The dissolving tank is connected to the third reactor, and the intermediate product 3 enters the dissolving tank and is dissolved in alkaline water to obtain the final product.

4. The preparation process of a scale inhibitor according to claim 3, characterized in that: The first reactor and the second reactor are made of stainless steel that is resistant to strong acids and alkalis.

Images