Method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother solution

Abstract

The invention discloses a method for preparing pseudo-boehmite by using sodium dichromate mother liquor to neutralize sodium aluminate and sodium chromate liquid, which comprises the following steps: simultaneously introducing the sodium dichromate mother liquor and the sodium aluminate and sodium chromate liquid into a stirring reactor in which soft water is added in advance, stirring to react, and increasing the concentration of reaction materials along with continuous introduction and finally achieving balance, after being balanced, the materials flow out from the overflow port and are transferred to the next process, and at the moment, the materials are still continuously fed, so that continuous feeding and continuous discharging are realized; and feeding the reacted material into an aging tank, heating, aging, washing with water, and drying to obtain the pseudo-boehmite product. According to the invention, resource utilization of the aluminum element in a chromium salt chemical production system is realized; meanwhile, the sodium dichromate mother liquor is used for providing an acid value for a neutralization reaction, and acid recycling is achieved; the pseudo-boehmite produced by the method disclosed by the invention has a relatively high specific surface area, a relatively large pore volume and a relatively concentrated average pore size.

Description

Technical Field

[0001] The invention belongs to the technical field of pseudo-boehmite material preparation, and in particular relates to a method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate liquid with sodium dichromate mother liquid. Background Art

[0002] Catalytic cracking (FCC) is an important means of secondary processing of crude oil, and catalysts are the core technology of catalytic cracking. Due to its large molecular size, heavy oil is difficult to enter the molecular sieve, and its cracking mainly occurs on the catalytic cracking carrier. At present, the active carrier of domestic catalytic cracking catalysts is mainly provided by alumina, and the alumina precursor used is mainly pseudo-boehmite.

[0003] There are many existing methods for preparing pseudo-boehmite, some of which have been industrialized, and some are still in the experimental research stage. The following are the known methods for preparing pseudo-boehmite:

[0004] (1) Alcohol aluminum method: The alcohol aluminum method is a method currently used abroad to prepare high-purity pseudo-boehmite, using aluminum and higher alcohols as raw materials. Its preparation process: aluminum and alcohol react to form alcohol aluminum, which is then reduced to aldehyde and then converted into new alcohol aluminum, which is hydrolyzed to obtain high-purity pseudo-boehmite. This method is complex to prepare, the pore size of the product obtained is small, which cannot meet the requirements of catalytic cracking, and the raw material cost is high.

[0005] (2) Carbonization method: Carbonization method is currently the most commonly used industrial method for preparing pseudo-boehmite in China. It uses industrial sodium aluminate and carbon dioxide as raw materials. The carbonization method uses industrial waste as raw materials, meets the requirements of green chemical production, and has low production costs. However, this method is a gas-liquid two-phase reaction process, which easily causes uneven mixing of raw materials during the preparation process, and some sodium aluminate is easily hydrolyzed to form gibbsite.

[0006] (3) Acid method: The acid method is a preparation method using aluminum salt and alkali as raw materials. This method is simple to prepare pseudo-boehmite and the raw materials are easy to obtain. However, the reaction conditions of this method are difficult to control, which can easily lead to unstable product quality.

[0007] (4) Alkali method: The alkaline method uses aluminate and acidic substances as raw materials. The product prepared by this method has obvious hard agglomeration, and sodium aluminate easily generates gibbsite in an alkaline environment.

[0008] (5) Hydrothermal synthesis method: Hydrothermal synthesis method is a crystal preparation method that has received much attention at home and abroad. This method regulates the particle size and morphology of the product by controlling the reaction conditions. The methods for preparing pseudo-boehmite include: hydrothermal alcohol aluminum method, hydrothermal aluminum salt method, and hydrothermal crystallization method. The pseudo-boehmite prepared by these methods has a high degree of crystallinity, loose samples, and relatively concentrated pore sizes. However, this method has a long reaction time, requires an organic template in the preparation process, is costly, and is difficult to control reaction conditions.

[0009] (6) Double aluminum method: The double aluminum method uses aluminum salt and aluminate as raw materials. This method is simple to prepare and operate, has mild reaction conditions, high product purity, no impurities such as gibbsite are generated, and the raw materials are cheap and easy to obtain.

[0010] Although there are a variety of methods for preparing pseudo-boehmite in the prior art, these methods all have certain disadvantages, and from the perspective of raw materials, these methods all use finished raw materials and do not consider the efficient utilization of resources, which leads to high costs for producing pseudo-boehmite. In addition, the performance of the pseudo-boehmite prepared in the prior art is relatively poor, and cannot fully meet the industrial application of pseudo-boehmite. Summary of the invention

[0011] The invention relates to using sodium aluminate in the leaching solution of chromium salt calcium-free roasted clinker as an aluminum source, utilizing one or a mixture of sodium dichromate mother liquor produced by a sulfuric acid method and a sodium dichromate mother liquor produced by a carbonization method in the production and processing process of a chromium salt chemical enterprise to provide an acid value, and then reacting to prepare pseudo-boehmite, which is of great significance in terms of developing a circular economy and taking the path of efficient resource utilization.

[0012] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0013] In order to achieve these purposes and other advantages according to the present invention, a method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother solution is provided, comprising the following steps:

[0014] Step 1, introducing sodium dichromate mother liquor and sodium aluminate sodium chromate liquid into a stirred reactor pre-added with soft water at the same time, stirring for reaction, aluminum ions in the sodium aluminate sodium chromate liquid are rapidly hydrolyzed to form pseudo-boehmite crystals, the concentration of the reaction materials increases with continuous introduction and eventually reaches pH balance, after equilibrium, the materials flow out from the overflow port and transfer to the next process, at this time, the materials are still continuously introduced to achieve continuous feeding and continuous discharging;

[0015] Step 2: The reacted material is sent to an aging tank and then subjected to temperature-raising aging, water washing, and drying processes to produce a pseudo-boehmite product.

[0016] Preferably, the sodium dichromate mother liquor is one of the concentrated mother liquor produced by the sulfuric acid process to produce sodium dichromate, the concentrated mother liquor produced by the carbonization process to produce sodium dichromate, or a mixture of the two; the pH balance is a pH value of 6-9.

[0017] Preferably, the acid value content in the sodium dichromate mother liquor is 180-400 g / L in terms of sulfuric acid.

[0018] Preferably, the sodium aluminate and sodium chromate solution is a leaching solution obtained by adding water to calcium-free roasted clinker produced by calcium-free roasting to produce sodium chromate.

[0019] Preferably, the sodium chromate content in the sodium aluminate and sodium chromate solution is 180-350 g / L, and the sodium aluminate content is 10-35 g / L.

[0020] Preferably, in the step 1, a continuous parallel flow neutralization method is adopted, and the sodium dichromate mother liquor and the sodium aluminate sodium chromate solution are simultaneously introduced into a stirred reactor into which 1 / 3 soft water is pre-added at a fixed flow rate; the introduction flow rate of the sodium dichromate mother liquor is 1-7m 3 / hour, the flow rate of sodium aluminate and sodium chromate solution is 10-40m 3 / hour. The method adopts the continuous parallel flow neutralization method. Compared with the traditional production method of pseudo-boehmite, this method can realize automation and continuity; the whole production process is more efficient and simple.

[0021] Preferably, in step 1, the speed of the stirring reaction is 85-238 rpm.

[0022] Preferably, in step 1, the reaction temperature of the stirring reaction is controlled at 45-75° C., and the pH value is controlled between 6.0-10.5 during the stirring reaction.

[0023] Preferably, in the step 2, the reacted material is added to a supercritical carbon dioxide reactor in an amount of 1 / 3 of the capacity of the supercritical carbon dioxide reactor, and then carbon dioxide is introduced to form supercritical carbon dioxide at a temperature of 60 to 75° C. and a pressure of 20 to 25 MPa. The reacted material is stirred with supercritical carbon dioxide for 1 to 2 hours, and then the pressure is released. The material after the pressure release is sent to an aging tank and then subjected to temperature aging, water washing, and drying steps to produce a pseudo-boehmite product.

[0024] Preferably, the temperature rise aging time is controlled between 1 and 5 hours.

[0025] Preferably, the temperature of the temperature-elevated aging is controlled at 85 to 95°C.

[0026] The present invention has at least the following beneficial effects:

[0027] (1) The present invention utilizes the calcium-free roasted clinker leaching liquid in the chromium salt chemical production process as the aluminum-containing raw material, and uses one or a mixture of the sodium dichromate mother liquor produced by the sulfuric acid method and the sodium dichromate mother liquor produced by the carbonization method in the chromium salt chemical production process to provide acid value, and then reacts to prepare pseudo-boehmite, thereby fully realizing the efficient utilization of resources and eliminating the waste of secondary resources; the method realizes the resource utilization of aluminum elements in the chromium salt chemical production system; at the same time, the sodium dichromate mother liquor is used to provide acid value for the neutralization reaction, thereby realizing the recycling of acid;

[0028] (2) The pseudo-boehmite produced by the present invention has a higher specific surface area, a larger pore volume and a relatively concentrated average pore size. According to feedback from catalyst production enterprises after use, the processed catalyst has a good wear resistance index and stability.

[0029] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0031] It should be understood that terms such as “having”, “including” and “comprising” used herein do not specify the existence or addition of one or more other elements or combinations thereof.

[0032] Embodiment 1:

[0033] A method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor comprises the following steps:

[0034] Step 1: Use electromagnetic flowmeter and regulating valve to control the flow rate of sodium dichromate mother liquor (acid value is 180g / L in sulfuric acid) and sodium aluminate sodium chromate solution (sodium chromate content is 198g / L, sodium aluminate content is 25g / L). The flow rate of sodium dichromate mother liquor is 2.3m 3 / hour, the flow rate of sodium aluminate and sodium chromate solution is 18.5m 3 / hour; start the centrifugal pump and simultaneously flow the sodium dichromate mother liquor and the sodium aluminate sodium chromate liquid into the high-intensity stirred reactor in parallel; pre-add 1 / 3 of soft water into the 12-cubic-meter reactor; set the speed of high-speed stirring at 85rpm; turn on the heat exchanger to adjust the temperature of the incoming material, keep the material reaction temperature in the range of 48-50°C, and keep the pH value of the neutralization reaction in the range of 6.3-6.5; the reaction material flows out from the overflow port and transfers to the next process, at which time the material is still continuously introduced to achieve continuous feeding and continuous discharging; the inventor of the present invention has found that in order to make the reaction faster and more efficient, the inventor adopts a continuous parallel flow neutralization method. Compared with the traditional production method of pseudo-boehmite, the present invention can achieve continuous feeding, and the whole production process is more efficient and simple;

[0035] Step 2: The reacted material is sent to an aging tank and then heated to 85°C for aging for 1.5 hours; then solid-liquid separation is performed to remove sodium chromate, and water is added to wash to remove residual soluble sodium salt; the filter cake after sodium washing is dried by a rotary flash drying device to produce a pseudo-boehmite product;

[0036] The results of sampling and analysis are as follows: pseudo-boehmite peptization index is 95.5%, specific surface area is 306m 2 / g, pore volume 0.54mL.

[0037] Embodiment 2:

[0038] A method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor comprises the following steps:

[0039] Step 1: Use electromagnetic flowmeter and regulating valve to control the flow rate of sodium dichromate mother liquor (acid value is 165g / L in sulfuric acid) and sodium aluminate sodium chromate solution (sodium chromate content is 203g / L, sodium aluminate content is 32g / L). The flow rate of sodium dichromate mother liquor is 3.5m 3 / hour, the flow rate of sodium aluminate and sodium chromate solution is 23m 3 / hour; start the centrifugal pump and simultaneously flow the sodium dichromate mother liquor and the sodium aluminate and sodium chromate liquid into the high-intensity stirred reactor in parallel; pre-add 1 / 3 of soft water into the 12-cubic-meter reactor; set the speed of high-speed stirring at 185rpm; start the heat exchanger to adjust the temperature of the incoming materials, keep the material reaction temperature in the range of 70-72℃, and keep the pH value of the neutralization reaction in the range of 9.0-9.5; the reaction materials flow out from the overflow port and transfer to the next process, and at this time, continue to feed the materials to achieve continuous feeding and continuous discharging;

[0040] Step 2: The reacted material is sent to an aging tank and then heated to 92°C for aging for 2 hours; then solid-liquid separation is performed to remove sodium chromate, and water is added to wash to remove the residual soluble sodium salt; the filter cake after sodium washing is dried by a rotary flash drying device to produce a pseudo-boehmite product;

[0041] The results of sampling and analysis are as follows: pseudo-boehmite peptization index is 95.8%, specific surface area is 313m 2 / g, pore volume 0.55ml.

[0042] Embodiment 3:

[0043] A method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor comprises the following steps:

[0044] Step 1: Use electromagnetic flowmeter and regulating valve to control the flow rate of sodium dichromate mother liquor (acid value is 145g / L in sulfuric acid) and sodium aluminate sodium chromate solution (sodium chromate content is 180g / L, sodium aluminate content is 16g / L). The flow rate of sodium dichromate mother liquor is 5.5m 3 / hour, the flow rate of sodium aluminate and sodium chromate solution is 21.5m 3 / hour; start the centrifugal pump and simultaneously flow the sodium dichromate solution and the sodium aluminate and sodium chromate solution into the high-intensity stirred reactor in parallel; pre-add 1 / 3 of soft water into the 12-cubic-meter reactor; set the speed of high-speed stirring at 105rpm; start the heat exchanger to adjust the temperature of the incoming materials, keep the reaction temperature of the materials in the range of 75-80℃, and keep the pH value of the neutralization reaction in the range of 9.5-10; the reaction materials flow out from the overflow port and transfer to the next process, at this time, continue to feed the materials to achieve continuous feeding and continuous discharging;

[0045] Step 2: The reacted material is sent to an aging tank and then heated to 95°C for aging for 1 hour; then solid-liquid separation is performed to remove sodium chromate, and water is added to wash to remove residual soluble sodium salt; the filter cake after sodium washing is dried by a rotary flash drying device to produce a pseudo-boehmite product;

[0046] The sampling and analysis results are as follows: the peptization index of pseudo-boehmite is 96.5%, the specific surface area is 324m2 / g, and the pore volume is 0.54ml.

[0047] Embodiment 4:

[0048] A method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor comprises the following steps:

[0049] Step 1: Use electromagnetic flowmeter and regulating valve to control the flow rate of sodium dichromate mother liquor (acid value is 152g / L in terms of sulfuric acid) and sodium aluminate sodium chromate solution (sodium chromate content is 187g / L, sodium aluminate content is 18.5g / L). The flow rate of sodium dichromate mother liquor is 6.5m 3 / hour, the flow rate of sodium aluminate and sodium chromate solution is 24m 3 / hour; start the centrifugal pump and simultaneously flow the sodium dichromate mother liquor and the sodium aluminate and sodium chromate liquid into the high-intensity stirring reactor in parallel; pre-add 1 / 3 of soft water into the 12-cubic-meter reactor; set the speed of high-speed stirring at 205rpm; start the heat exchanger to adjust the temperature of the incoming materials, keep the material reaction temperature in the range of 80-85℃, and keep the pH value of the neutralization reaction in the range of 10.0-10.5; the reaction materials flow out from the overflow port and transfer to the next process, at this time, continue to feed the materials to achieve continuous feeding and continuous discharging;

[0050] Step 2: The reacted material is sent to an aging tank and then heated to 92°C for aging for 3 hours; then solid-liquid separation is performed to remove sodium chromate, and water is added to wash to remove the residual soluble sodium salt; the filter cake after sodium washing is dried by a rotary flash drying device to produce a pseudo-boehmite product;

[0051] The results of sampling and analysis are as follows: pseudo-boehmite peptization index is 96.8%, specific surface area is 316m 2 / g, pore volume 0.51ml.

[0052] Embodiment 5:

[0053] A method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor comprises the following steps:

[0054] Step 1: Use electromagnetic flowmeter and regulating valve to control the flow rate of sodium dichromate mother liquor (acid value is 126g / L in sulfuric acid) and sodium aluminate sodium chromate solution (sodium chromate content is 123g / L, sodium aluminate content is 9.5g / L). The flow rate of sodium dichromate mother liquor is 7m 3 / hour, the flow rate of sodium aluminate and sodium chromate solution is 36m 3 / hour; start the centrifugal pump and simultaneously flow the sodium dichromate mother liquor and the sodium aluminate and sodium chromate liquid into the high-intensity stirred reactor in parallel; pre-add 1 / 3 of soft water into the 12-cubic-meter reactor; set the speed of high-speed stirring at 235rpm; start the heat exchanger to adjust the temperature of the incoming materials, keep the material reaction temperature in the range of 80-85℃, and keep the pH value of the neutralization reaction in the range of 8.5-9.0; the reaction materials flow out from the overflow port and transfer to the next process, at this time, continue to feed the materials to achieve continuous feeding and continuous discharging;

[0055] Step 2: The reacted material is sent to an aging tank and then heated to 91.5°C for aging for 4 hours; then solid-liquid separation is performed to remove sodium chromate, and water is added to wash to remove residual soluble sodium salt; the filter cake after sodium washing is dried by a rotary flash drying device to produce a pseudo-boehmite product;

[0056] The results of sampling and analysis are as follows: pseudo-boehmite peptization index is 95.7%, specific surface area is 318m 2 / g, pore volume 0.57ml.

[0057] Embodiment 6:

[0058] A method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor comprises the following steps:

[0059] Step 1: Use electromagnetic flowmeter and regulating valve to control the flow rate of sodium dichromate mother liquor (acid value is 180g / L in sulfuric acid) and sodium aluminate sodium chromate solution (sodium chromate content is 198g / L, sodium aluminate content is 25g / L). The flow rate of sodium dichromate mother liquor is 2.3m 3 / hour, the flow rate of sodium aluminate and sodium chromate solution is 18.5m 3 / hour; start the centrifugal pump and simultaneously flow the sodium dichromate mother liquor and the sodium aluminate and sodium chromate liquid into the high-intensity stirring reactor in parallel; pre-add 1 / 3 of soft water into the 12-cubic-meter reactor; set the speed of high-speed stirring at 85rpm; start the heat exchanger to adjust the temperature of the incoming materials, keep the material reaction temperature in the range of 48-50℃, and keep the pH value of the neutralization reaction in the range of 6.3-6.5; the reaction materials flow out from the overflow port and transfer to the next process, at this time, continue to feed the materials to achieve continuous feeding and continuous discharging;

[0060] Step 2: Add the reacted material to a supercritical carbon dioxide reactor in an amount of 1 / 3 of the capacity of the supercritical carbon dioxide reactor, then introduce carbon dioxide to form supercritical carbon dioxide at a temperature of 65° C. and a pressure of 20 MPa, stir the reacted material with supercritical carbon dioxide for 1 hour, then release the pressure, send the depressurized material to an aging tank and then heat it to 85° C. for aging for 1.5 hours; then separate the solid and liquid to remove sodium chromate, add water to wash and remove the residual soluble sodium salt; dry the filter cake after sodium washing with a rotary flash drying device to make pseudo-boehmite Stone products; during the production process, the inventors found that the material after the reaction in step 1 had an incomplete reaction problem, which may be due to the incomplete reaction caused by continuous feeding. Therefore, after repeated research, the inventors re-processed the reacted material, and made the reacted material react more thoroughly by reacting in supercritical carbon dioxide, re-processing and then aging. In addition, the supercritical carbon dioxide with low viscosity and low surface tension can quickly penetrate into the micropores of the reacted material and clean the micropores, so that the performance of the prepared pseudo-boehmite is better;

[0061] The results of sampling and analysis are as follows: pseudo-boehmite peptization index is 97.8%, specific surface area is 375m 2 / g, pore volume 0.56mL.

[0062] Embodiment 7:

[0063] A method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor comprises the following steps:

[0064] Step 1: Use electromagnetic flowmeter and regulating valve to control the flow rate of sodium dichromate mother liquor (acid value is 165g / L in sulfuric acid) and sodium aluminate sodium chromate solution (sodium chromate content is 203g / L, sodium aluminate content is 32g / L). The flow rate of sodium dichromate mother liquor is 3.5m 3 / hour, the flow rate of sodium aluminate and sodium chromate solution is 23m 3 / hour; start the centrifugal pump and simultaneously flow the sodium dichromate mother liquor and the sodium aluminate and sodium chromate liquid into the high-intensity stirred reactor in parallel; pre-add 1 / 3 of soft water into the 12-cubic-meter reactor; set the speed of high-speed stirring at 185rpm; start the heat exchanger to adjust the temperature of the incoming materials, keep the material reaction temperature in the range of 70-72℃, and keep the pH value of the neutralization reaction in the range of 9.0-9.5; the reaction materials flow out from the overflow port and transfer to the next process, and at this time, continue to feed the materials to achieve continuous feeding and continuous discharging;

[0065] Step 2: Add the reacted materials into a supercritical carbon dioxide reactor in an amount of 1 / 3 of the capacity of the supercritical carbon dioxide reactor, then introduce carbon dioxide to form supercritical carbon dioxide at a temperature of 65° C. and a pressure of 20 MPa, stir the reacted materials with supercritical carbon dioxide for 1 hour, then release the pressure, and send the reacted materials into an aging tank and then heat them to 92° C. for aging for 2 hours; then separate the solid and liquid to remove sodium chromate, add water to wash and remove the residual soluble sodium salt; dry the filter cake after sodium washing with a rotary flash drying device to prepare a pseudo-boehmite product;

[0066] The results of sampling and analysis are as follows: pseudo-boehmite peptization index is 98.2%, specific surface area is 381m 2 / g, pore volume 0.58ml.

[0067] The present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent substitution of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor, characterized in that: The following steps are involved: Step 1, introducing sodium dichromate mother liquor and sodium aluminate sodium chromate liquid into a stirred reactor pre-added with soft water at the same time, stirring for reaction, the concentration of the reaction materials increases with continuous introduction and eventually reaches pH balance, after equilibrium, the materials flow out from the overflow port and transfer to the next process, at this time, the materials are still continuously introduced to achieve continuous feeding and continuous discharging; Step 2: The reacted material is sent to an aging tank and then subjected to temperature-raising aging, water washing, and drying processes to produce a pseudo-boehmite product.

2. The method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor according to claim 1, characterized in that: The sodium dichromate mother liquor is one of the concentrated mother liquor produced by producing sodium dichromate by sulfuric acid method and the concentrated mother liquor produced by producing sodium dichromate by carbonization method, or a mixture of the two.

3. The method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor according to claim 2, characterized in that: The acid value content in the sodium dichromate mother liquor is 180-400 g / L in terms of sulfuric acid.

4. The method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor according to claim 1, characterized in that: The sodium aluminate and sodium chromate solution is a leaching solution obtained by adding water to calcium-free roasted clinker produced by calcium-free roasting to produce sodium chromate.

5. The method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor according to claim 4, characterized in that: The sodium aluminate and sodium chromate solution has a sodium chromate content of 180-350 g / L and a sodium aluminate content of 10-35 g / L.

6. The method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother solution according to claim 1, characterized in that: In the step 1, a continuous parallel flow neutralization method is adopted to simultaneously introduce the sodium dichromate mother liquor and the sodium aluminate sodium chromate solution into a stirred reactor into which 1 / 3 soft water is pre-added at a fixed flow rate; the introduction flow rate of the sodium dichromate mother liquor is 1-7m 3 / hour, the flow rate of sodium aluminate and sodium chromate solution is 10-40m 3 / Hour.

7. The method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor according to claim 1, characterized in that: In the step 1, the rotation speed of the stirring reaction is 85-238 rpm.

8. The method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor according to claim 1, characterized in that: In the step 1, the reaction temperature of the stirring reaction is controlled at 45-75° C., and the pH value is controlled between 6.0-10.5 during the stirring reaction.

9. The method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother liquor according to claim 1, characterized in that: The time of the temperature rise aging is controlled between 1 and 5 hours.

10. The method for preparing pseudo-boehmite by neutralizing sodium aluminate and sodium chromate solution with sodium dichromate mother solution according to claim 1, characterized in that: The temperature of the temperature-raising aging is controlled at 85 to 95°C.