Seed crystal for synchronously removing calcium and silicon in wastewater, preparation method of seed crystal and nucleation granulation process

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a seed crystal for synchronously removing calcium and silicon in wastewater, a preparation method of the seed crystal and a nucleation granulation process. According to the preparation method disclosed by the invention, a calcium source, a magnesium source and a silicon source are used as raw materials, and the special seed crystal capable of synchronously removing calcium and silicon in the wastewater can be obtained through a one-step high-temperature hydrothermal method. In the nucleation granulation process, the special seed crystal can intensify capture of precipitates formed by calcium ions and silicate ions, so that the precipitates are tightly wrapped on the special seed crystal to form a water-free granulation body, the calcium ions and the silicon ions in the wastewater are synchronously removed, and the treatment method is efficient, short in flow, high in resource utilization rate and low in cost. The industrial application is facilitated.

Description

Technical Field

[0001] The present disclosure relates to the technical field of wastewater treatment, and particularly to a seed crystal for synchronously removing calcium and silicon from wastewater, a preparation method thereof, and a nucleation granulation process. Background Art

[0002] Traditional coal chemical industry generally refers to coal gasification, liquefaction, coking and tar processing, calcium carbide acetylene chemical industry, etc., and also includes the preparation of carbon materials and coal-based polymer materials using coal as raw materials. New coal chemical industry takes coal gasification as the leading process, including the production of methanol, acetic acid or dimethyl ether from coal. While the coal chemical industry is developing rapidly, it has brought relatively large environmental problems. Whether it is traditional coal chemical industry or new coal chemical industry, a large amount of industrial wastewater will be generated during their production processes. The wastewater has a complex composition and contains various metal ions, such as scale-forming ions like calcium and silicon. At the same time, it also contains toxic and harmful substances such as cyanide, thiocyanate, polycyclic aromatic compounds, and heterocyclic compounds. Therefore, the treatment of this wastewater has become one of the difficult problems in current industrial wastewater treatment and reuse. The treatment and reuse technology of coal chemical wastewater has gradually become a bottleneck for the rapid development of the coal chemical industry. Seeking an economical and effective wastewater treatment method is of great significance.

[0003] During the reuse process of coal chemical wastewater, due to the high concentration of calcium and silicon ions in the wastewater, pipeline scaling will occur, which has become a key influencing factor for wastewater reuse. Therefore, it is necessary to remove the scale-forming calcium and silicon ions from the wastewater. The existing treatment technologies are mostly chemical precipitation methods, which will produce a large amount of loose sludge and require further pressure filtration assistance. Therefore, they have the disadvantages of high energy consumption and large equipment floor area.

[0004] In summary, in view of the various defects existing in the treatment of calcium and silicon in existing traditional coal chemical wastewater, it is necessary to find a treatment method that is efficient, has a short process, and can synchronously remove them. Summary of the Invention

[0005] In order to solve the above technical problems, the present disclosure provides a seed crystal for synchronously removing calcium and silicon from wastewater, a preparation method thereof, and a nucleation granulation process. The preparation method synthesizes a special seed crystal for synchronously removing calcium and silicon from wastewater through a one-step high-temperature hydrothermal method. Applying the seed crystal to the nucleation granulation process can synchronously remove calcium and silicon from the wastewater, improve the reuse rate of the wastewater, and reduce the risk of pipeline scaling.

[0006] In a first aspect, the present disclosure provides a preparation method of a seed crystal for synchronously removing calcium and silicon from wastewater, and the preparation method includes the following steps:

[0007] (1) Mix a calcium source, a magnesium source, and a silicon source with water to obtain a precursor solution;

[0008] (2) Place the precursor solution described in step (1) in a high-pressure reactor and react it under the condition of 100 - 200 °C to obtain seeds for synchronously removing calcium and silicon from wastewater.

[0009] Among them, the reaction temperature can be selected as 100 °C, 120 °C, 140 °C, 160 °C, 180 °C or 200 °C, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0010] The seeds described in the present disclosure are made from a calcium source, a magnesium source, and a silicon source as raw materials. Through a one-step high-temperature hydrothermal method, seeds (calcium-silicon-magnesium complex) specifically for synchronously removing calcium and silicon from wastewater can be obtained. The preparation method is simple and fast. The obtained seeds can efficiently and synchronously remove calcium and silicon ions from wastewater, purify the water quality, and at the same time avoid pipeline scaling, which is of great significance for the treatment of coal chemical wastewater.

[0011] The following are the preferred technical solutions of the present disclosure, but not the limitations of the technical solutions provided by the present disclosure. Through the following technical solutions, the technical objectives and beneficial effects of the present disclosure can be better achieved.

[0012] As a preferred technical solution of the present disclosure, the calcium source described in step (1) includes soluble calcium salts and has a purity of not less than 95%.

[0013] Preferably, the magnesium source described in step (1) includes soluble magnesium salts and has a purity of not less than 95%.

[0014] Preferably, the silicon source described in step (1) includes silicate and has a purity of not less than 95%.

[0015] Preferably, the mass ratio of the calcium source, the magnesium source, and the silicon source in step (1) is (1 - 2):(1 - 2):(2 - 3), such as 1:1:2, 1:2:2, 1:1:3, 2:2:3 or 2:2:2, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0016] As a preferred technical solution of the present disclosure, control the pH of the precursor solution in step (1) to be 6 - 8, such as 6, 6.5, 7, 7.5 or 8, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0017] Generally, hydrochloric acid or sodium hydroxide is used to adjust the pH value of the precursor solution.

[0018] As a preferred technical solution of the present disclosure, the volume of the precursor solution in step (2) in the high-pressure reactor does not exceed 2 / 3 of the volume of the high-pressure reactor.

[0019] Preferably, the reaction time in step (2) is 6 - 12 h, such as 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, or 12 h, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0020] In the present disclosure, appropriate raw material ratios, the pH of the reaction system, reaction temperature, and reaction time ensure the quality of the obtained seed crystals.

[0021] As a preferred technical solution of the present disclosure, after the reaction in step (2) is completed, cooling, washing, and drying are successively carried out.

[0022] Preferably, the cooling method includes natural cooling.

[0023] Preferably, the drying time is 30 - 60 min, such as 30 min, 40 min, 50 min, or 60 min, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0024] Preferably, the drying temperature is 80 - 120 °C, such as 80 °C, 90 °C, 100 °C, 110 °C, or 120 °C, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0025] As a preferred technical solution of the present disclosure, in the seed crystal for synchronously removing calcium and silicon from wastewater obtained in step (2), the calcium-containing component is calculated as CaO, and the purity is greater than 30%, such as 30%, 35%, 40%, 45%, or 50%, etc.; the silicon-containing component is calculated as SiO 2 and the purity is greater than 30%, such as 30%, 35%, 40%, 45%, or 50%, etc., but is not limited to the listed values, and other unlisted values within the above range are equally applicable.

[0026] In a second aspect, the present disclosure provides a seed crystal for synchronously removing calcium and silicon from wastewater, which is prepared by the preparation method as described in the first aspect.

[0027] In a third aspect, the present disclosure provides a nuclear crystal granulation process, and the nuclear crystal granulation process is carried out using the seed crystal prepared by the preparation method as described in the first aspect;

[0028] The nuclear crystal granulation process includes:

[0029] (1) Filling the seed crystal into a nuclear crystal granulation reactor;

[0030] (2) Passing calcium- and silicon-containing wastewater and a crystallization inducer into the lower part of the nuclear crystal granulation reactor to make the seed crystal in a fluidized state;

[0031] Calcium ions and silicate ions in the calcium- and silicon-containing wastewater react with the crystal seeding agent to nucleate and grow on the surface of the crystal seeds in the form of precipitation, forming granulated bodies and realizing the purification of the calcium- and silicon-containing wastewater.

[0032] As a preferred technical solution of the present disclosure, the nuclear crystal granulation reactor includes an outer cylinder and an inner cylinder. The inner cylinder is suspended in the outer cylinder and is vertically through.

[0033] At least one feed pipe is provided at the lower end of the side wall of the outer cylinder and is located below the lower opening of the inner cylinder for introducing the calcium- and silicon-containing wastewater and the crystal seeding agent.

[0034] A water outlet pipe is provided at the upper end or the top of the side wall of the outer cylinder for discharging the regenerated water.

[0035] A granulated body discharge pipe is provided at the bottom of the outer cylinder for discharging the granulated bodies.

[0036] Preferably, a toothed overflow weir is provided at the upper opening of the inner cylinder.

[0037] As a preferred technical solution of the present disclosure, there are 2 feed pipes, which are located at the same horizontal height and are oppositely arranged. One is for introducing the calcium- and silicon-containing wastewater, and the other is for introducing the crystal seeding agent.

[0038] In the present disclosure, the opposite arrangement means that the angle between the two feed pipes is 180°, and this arrangement helps the full reaction of the crystal seeding agent and the calcium and silicon ions in the influent water.

[0039] As a preferred technical solution of the present disclosure, the crystal seeds in step (1) are filled in the inner cylinder, and the filling height is 20-50% of the height of the inner cylinder, such as 20%, 25%, 30%, 35%, 40%, 45% or 50%, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0040] As a preferred technical solution of the present disclosure, the pH of the reaction system in step (2) is controlled to be 8.5-9.5, such as 8.5, 8.7, 9.0, 9.3 or 9.5, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0041] In the present disclosure, if the added crystal seeding agent can control the pH of the reaction system within the above range, no additional adjustment is required. In addition, the pH of the wastewater can also be pre-adjusted before it is introduced into the nuclear crystal granulation reactor.

[0042] Preferably, an acid solution and / or an alkali solution are used to control the pH of the reaction system.

[0043] Preferably, the acid solution includes sulfuric acid and / or hydrochloric acid.

[0044] Preferably, the alkaline solution includes sodium hydroxide solution and / or potassium hydroxide solution.

[0045] Preferably, the concentration of the alkaline solution does not exceed 5 mol / L, such as 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0046] In the present disclosure, when adjusting the pH with an alkaline solution, its concentration should not be too high, otherwise it will cause seed poisoning and reduce the efficiency.

[0047] As a preferred technical solution of the present disclosure, the seeding agent in step (2) is introduced in the form of a solution, and the seeding agent includes sodium aluminate.

[0048] In the present disclosure, the concentration of the seeding agent, the flow rate of the seeding agent introduced, and the flow rate of the wastewater introduced are adjusted and controlled by those skilled in the art according to specific situations such as the wastewater treatment concentration.

[0049] As a preferred technical solution of the present disclosure, in the nucleation and granulation process, there is at least 1 nucleation and granulation reactor;

[0050] When there are no less than 2 nucleation and granulation reactors, a plurality of the nucleation and granulation reactors are arranged in series, and the reclaimed water obtained from the previous nucleation and granulation reactor is used as the feed wastewater for the next nucleation and granulation reactor.

[0051] Multi-stage continuous treatment helps to improve the removal rate of calcium ions and silicate ions in the calcium- and silicon-containing wastewater.

[0052] Generally, if only one nucleation and granulation reactor is used for primary wastewater treatment, in the calcium- and silicon-containing wastewater, the concentration of calcium ions does not exceed 400 mg / L, and the concentration of silicate ions does not exceed 100 mg / L; if the concentrations of both are too high, additional nucleation and granulation reactors need to be further connected in series for multi-stage treatment to meet the treatment standards.

[0053] The technical solutions provided by the embodiments of the present disclosure have the following advantages compared with the prior art:

[0054] (1) The preparation method described in the present disclosure uses calcium source, magnesium source and silicon source as raw materials, and through a one-step high-temperature hydrothermal method, a special crystal seed for synchronously removing calcium and silicon in wastewater can be obtained;

[0055] (2) The nucleation and granulation method described in the present disclosure can achieve the synchronous removal of calcium and silicon ions in coal chemical wastewater through the cooperation of the crystal seed and the seeding agent, thereby improving the reuse rate of wastewater and reducing the scaling risk of pipelines;

[0056] (3) The nuclear crystal granulation method described in the present disclosure realizes the synchronous removal of calcium and silicon in the same device, without other redundant steps and devices, and finally forms dense granulated bodies, eliminating the need for sludge dewatering. Description of the Drawings

[0057] The drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present disclosure and, together with the specification, are used to explain the principles of the present disclosure.

[0058] To more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0059] Figure 1 It is a schematic structural diagram of the nuclear crystal granulation reactor according to the specific embodiment of the present disclosure;

[0060] Figure 2 It is an SEM image of the seed crystal for synchronously removing calcium and silicon in wastewater according to Embodiment 1 of the present disclosure.

[0061] Among them, 1. Outer cylinder; 2. Inner cylinder; 3. Wastewater feed pipe; 4. Inducing crystal agent feed pipe; 5. Water outlet pipe; 6. Granulated body discharge pipe; 7. Tooth-shaped overflow weir. Detailed Embodiments

[0062] In order to more clearly understand the above-mentioned objects, features, and advantages of the present disclosure, the following will further describe the solutions of the present disclosure. It should be noted that, without conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other.

[0063] Many specific details are set forth in the following description in order to fully understand the present disclosure, but the present disclosure can also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only a part of the embodiments of the present disclosure, rather than all of the embodiments.

[0064] The present disclosure provides a nuclear crystal granulation reaction device, the nuclear crystal granulation reaction device includes at least one nuclear crystal granulation reactor, and the structure of the nuclear crystal granulation reactor is as Figure 1 shown.

[0065] The nuclear crystal granulation reactor includes an outer cylinder 1 and an inner cylinder 2, the inner cylinder 2 is suspended in the outer cylinder 1 and is vertically through;

[0066] Two feed pipes are provided at the lower end of the side wall of the outer cylinder 1, namely a wastewater feed pipe 3 for introducing wastewater containing calcium and silicon, and an inducing crystal agent feed pipe 4 for introducing an inducing crystal agent;

[0067] Both the waste water feed pipe 3 and the crystal seeding agent feed pipe 4 are located below the lower end opening of the inner cylinder 2 and at the same horizontal height, and are arranged oppositely.

[0068] A water outlet pipe 5 is arranged at the upper end of the side wall of the outer cylinder 1 for discharging the reclaimed water.

[0069] A granule discharge pipe 6 is arranged at the bottom of the outer cylinder 1 for discharging the granules.

[0070] Further, when there are no less than 2 nucleation granulation reactors, a plurality of the nucleation granulation reactors are arranged in series, and the reclaimed water obtained from the previous nucleation granulation reactor is used as the feed waste water for the next nucleation granulation reactor.

[0071] Further, a toothed overflow weir 7 is arranged at the upper end opening of the inner cylinder 2.

[0072] Example 1

[0073] This example provides a preparation method of crystal seeds for synchronously removing calcium and silicon in waste water and a nucleation granulation process, and the preparation method includes the following steps:

[0074] (1) Mix calcium chloride, magnesium chloride and calcium silicate with water according to a mass ratio of 1:2:2 to obtain a precursor solution with a pH of 7.0.

[0075] (2) Place the precursor solution in step (1) in a high-pressure reactor, react at 100 °C for 6 h, after the reaction is completed, let the high-pressure reactor cool naturally to room temperature, wash the obtained solid, and then dry it at 80 °C for 30 min to obtain crystal seeds for synchronously removing calcium and silicon in waste water.

[0076] The SEM diagram of the obtained crystal seeds is as Figure 2 shown. It can be seen from Figure 2 that there are a large number of pores on the surface of the crystal seeds, indicating that the crystal seeds have a large specific surface area, which is beneficial to adsorb pollutants.

[0077] The nucleation granulation process includes:

[0078] (1) Carry out using the nucleation granulation reaction device described in the specific implementation manner, wherein there is 1 nucleation granulation reactor;

[0079] Fill the inner cylinder 2 of the nucleation granulation reactor with the crystal seeds, and the filling height is 20% of the height of the inner cylinder 2;

[0080] (2) The concentration of calcium ions in the waste water is 400 mg / L, the concentration of silicate ions is 100 mg / L, and the pH is adjusted to 8 with 4 mol / L sodium hydroxide solution.

[0081] The wastewater after pH adjustment is fed into the nuclear crystal granulation reactor at a flow rate of 500 L / h. Meanwhile, a sodium aluminate solution with a concentration of 550 mg / L is fed into the nuclear crystal granulation reactor at a flow rate of 50 L / h, making the seed crystals in a fluidized state and ensuring that the pH in the reaction system is 9.2;

[0082] Calcium ions and silicate ions in the wastewater react with sodium aluminate to nucleate and grow on the surface of the seed crystals in the form of precipitation, forming granulated bodies and achieving the purification of calcium- and silicon-containing wastewater;

[0083] The reclaimed water obtained after the above treatment is discharged from the water outlet pipe 5 of the nuclear crystal granulation reactor, and the granulated bodies obtained are discharged from the granulated body discharge pipe 6 of the nuclear crystal granulation reactor.

[0084] Example 2

[0085] This example provides a preparation method of seeds and a nuclear crystal granulation process for synchronously removing calcium and silicon in wastewater. The preparation method includes the following steps:

[0086] (1) Mix calcium chloride, magnesium sulfate, and calcium silicate in a mass ratio of 2:1:2, and add sodium hydroxide to obtain a precursor solution with a pH of 8.0;

[0087] (2) Place the precursor solution obtained in step (1) in a high-pressure reactor, react at 120 °C for 8 h, and after the reaction is completed, let the high-pressure reactor cool naturally to room temperature. Wash the obtained solid, and then dry it at 100 °C for 40 min to obtain seeds for synchronously removing calcium and silicon in wastewater.

[0088] The nuclear crystal granulation process includes:

[0089] (1) It is carried out using the nuclear crystal granulation reaction device described in the specific implementation manner. Among them, there are 2 nuclear crystal granulation reactors, which are named the primary nuclear crystal granulation reactor and the secondary nuclear crystal granulation reactor in sequence from upstream to downstream;

[0090] Fill the inner cylinder 2 of the primary nuclear crystal granulation reactor and the secondary nuclear crystal granulation reactor with the seeds, and the filling height is 25% of the height of the inner cylinder 2;

[0091] (2) The concentration of calcium ions in the wastewater is 600 mg / L, and the concentration of silicate ions is 200 mg / L. Adjust its pH to 8.5 using a 4 mol / L sodium hydroxide solution;

[0092] The wastewater after pH adjustment is fed into the primary nuclear crystal granulation reactor at a flow rate of 1000 L / h. Meanwhile, a sodium aluminate solution with a concentration of 550 mg / L is fed into the primary nuclear crystal granulation reactor at a flow rate of 100 L / h, making the seed crystals in a fluidized state and ensuring that the pH in the reaction system is 9;

[0093] Calcium ions and silicate ions in the wastewater react with sodium aluminate to nucleate and grow on the surface of the seed crystals in the form of precipitation, forming granulated bodies to achieve primary purification of the calcium- and silicon-containing wastewater (obtaining primary reclaimed water);

[0094] The primary reclaimed water obtained after the above treatment is discharged from the outlet pipe 5 of the primary nuclear crystal granulation reactor and enters the secondary nuclear crystal granulation reactor, and the obtained granulated bodies are discharged from the granulated body discharge pipe 6 of the primary nuclear crystal granulation reactor;

[0095] (3) Control the flow rate of the reclaimed water entering the secondary nuclear crystal granulation reactor to be 1000 L / h. Meanwhile, a sodium aluminate solution with a concentration of 500 mg / L is fed into the secondary nuclear crystal granulation reactor at a flow rate of 100 L / h, making the seed crystals in a fluidized state and ensuring that the pH in the reaction system is 9.5;

[0096] Calcium ions and silicate ions in the wastewater react with sodium aluminate to nucleate and grow on the surface of the seed crystals in the form of precipitation, forming granulated bodies to achieve secondary purification of the calcium- and silicon-containing wastewater (obtaining secondary reclaimed water);

[0097] The secondary reclaimed water obtained after the above treatment is discharged from the outlet pipe 5 of the secondary nuclear crystal granulation reactor, and the obtained granulated bodies are discharged from the granulated body discharge pipe 6 of the secondary nuclear crystal granulation reactor.

[0098] Example 3

[0099] This example provides a preparation method and a nuclear crystal granulation process for seeds used to simultaneously remove calcium and silicon from wastewater. The preparation method includes the following steps:

[0100] (1) Dissolve calcium chloride, magnesium chloride, and calcium silicate in water according to a mass ratio of 2:2:3 to obtain a precursor solution with a pH of 6.0;

[0101] (2) Place the precursor solution in step (1) in a high-pressure reaction kettle and react at 200 °C for 12 h. After the reaction is completed, let the high-pressure reaction kettle cool naturally to room temperature, wash the obtained solid, and then dry it at 120 °C for 60 min to obtain seeds for simultaneously removing calcium and silicon from wastewater.

[0102] The nuclear crystal granulation process refers to the nuclear crystal granulation process in Example 1, with the only difference being that the seeds used are replaced with the seeds prepared in this example.

[0103] Example 4

[0104] This example provides a method for preparing seeds for synchronously removing calcium and silicon in wastewater and a nuclear crystallization granulation process. The preparation method refers to the preparation method in Example 1, with the only difference being that in step (1), the mass ratio of the calcium source, magnesium source, and silicon source is 0.5:2:2.

[0105] The nuclear crystallization granulation process refers to the nuclear crystallization granulation process in Example 1, with the only difference being that the seeds used are replaced with the seeds prepared in this example.

[0106] Example 5

[0107] This example provides a method for preparing seeds for synchronously removing calcium and silicon in wastewater and a nuclear crystallization granulation process. The preparation method refers to the preparation method in Example 1, with the only difference being that in step (1), the mass ratio of the calcium source, magnesium source, and silicon source is 3:2:2.

[0108] The nuclear crystallization granulation process refers to the nuclear crystallization granulation process in Example 1, with the only difference being that the seeds used are replaced with the seeds prepared in this example.

[0109] Example 6

[0110] This example provides a method for preparing seeds for synchronously removing calcium and silicon in wastewater and a nuclear crystallization granulation process. The preparation method refers to the preparation method in Example 1, with the only difference being that in step (1), the mass ratio of the calcium source, magnesium source, and silicon source is 1:2:1.

[0111] The nuclear crystallization granulation process refers to the nuclear crystallization granulation process in Example 1, with the only difference being that the seeds used are replaced with the seeds prepared in this example.

[0112] Example 7

[0113] This example provides a method for preparing seeds for synchronously removing calcium and silicon in wastewater and a nuclear crystallization granulation process. The preparation method refers to the preparation method in Example 1, with the only difference being that in step (1), the mass ratio of the calcium source, magnesium source, and silicon source is 1:2:4.

[0114] The nuclear crystallization granulation process refers to the nuclear crystallization granulation process in Example 1, with the only difference being that the seeds used are replaced with the seeds prepared in this example.

[0115] Example 8

[0116] This embodiment provides a method for preparing seeds for synchronously removing calcium and silicon from wastewater and a nucleation granulation process. The preparation method refers to the preparation method in Embodiment 1, with the only difference being that in step (1), the pH of the precursor solution is adjusted to 5.0 by adding hydrochloric acid.

[0117] The nucleation granulation process refers to the nucleation granulation process in Embodiment 1, with the only difference being that the seeds used are replaced with the seeds prepared in this embodiment.

[0118] Example 9

[0119] This embodiment provides a method for preparing seeds for synchronously removing calcium and silicon from wastewater and a nucleation granulation process. The preparation method refers to the preparation method in Embodiment 1, with the only difference being that in step (1), the pH of the precursor solution is adjusted to 9.0 by adding sodium hydroxide.

[0120] The nucleation granulation process refers to the nucleation granulation process in Embodiment 1, with the only difference being that the seeds used are replaced with the seeds prepared in this embodiment.

[0121] Comparative Example 1

[0122] Referring to Example 1, this comparative example provides a nucleation granulation process for synchronously removing calcium and silicon from wastewater, with the only difference being that the seeds are replaced with commercially available seeds, garnet.

[0123] Comparative Example 2

[0124] This comparative example provides a method for preparing seeds for synchronously removing calcium and silicon from wastewater and a nucleation granulation process. The preparation method refers to the preparation method in Embodiment 1, with the only difference being that the reaction temperature in step (2) is 80 °C.

[0125] The nucleation granulation process refers to the nucleation granulation process in Embodiment 1, with the only difference being that the seeds used are replaced with the seeds prepared in this comparative example.

[0126] Comparative Example 3

[0127] This comparative example provides a method for preparing seeds for synchronously removing calcium and silicon from wastewater and a nucleation granulation process. The preparation method refers to the preparation method in Embodiment 3, with the only difference being that the reaction temperature in step (2) is 220 °C.

[0128] The nucleation granulation process refers to the nucleation granulation process in Embodiment 3, with the only difference being that the seeds used are replaced with the seeds prepared in this comparative example.

[0129] Result determination:

[0130] The calcium ion content, silicate ion content and turbidity of the reclaimed water obtained in Examples 1-9 and Comparative Examples 1-3 were measured, and the results are shown in Table 1.

[0131] Table 1

[0132]

[0133]

[0134] As can be seen from Table 1, in Example 1 and Examples 3-9, the seeds prepared by the preparation method of the present disclosure, in combination with the primary nucleation granulation process, can achieve the synchronous removal of calcium and silicon ions. The calcium ion removal rate reaches more than 75%, and at the same time, the silicate ion removal rate reaches more than 43%.

[0135] Furthermore, by controlling the preparation conditions of the seeds, higher-quality seeds can be obtained. For example, in Example 1 and Example 3, after the primary nucleation granulation treatment with higher-quality seeds, the calcium ion removal rate reaches more than 94%, and at the same time, the silicate ion removal rate reaches more than 87%.

[0136] In Example 2, due to the too high concentration of calcium and silicon ions in the wastewater, in the case of only using the primary nucleation granulation treatment, although the absolute removal amount increases, the relative removal amount (i.e., the removal rate) is low; after the secondary nucleation granulation treatment, the calcium ion removal rate reaches more than 96%, and the silicate ion removal rate reaches more than 95%.

[0137] In Comparative Example 1, the existing commercial seeds were used, and the synchronous and efficient removal of calcium and silicon ions could not be achieved, resulting in low removal rates of calcium ions and silicate ions.

[0138] In Comparative Examples 2-3, due to the failure to control the appropriate reaction temperature during the preparation of the seeds, the quality of the obtained seeds was poor, thus affecting their removal effects on calcium ions and silicate ions.

[0139] The above are only specific embodiments of the present disclosure, enabling those skilled in the art to understand or implement the present disclosure. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing seeds for synchronously removing calcium and silicon from wastewater, characterized in that: The preparation method comprises the following steps: (1) mixing a calcium source, a magnesium source and a silicon source with water to obtain a precursor solution; (2) placing the precursor solution of step (1) in a high-pressure reactor and reacting at 100-200° C. to obtain seed crystals for simultaneously removing calcium and silicon from wastewater.

2. The preparation method according to claim 1, characterized in that: The calcium source in step (1) comprises a soluble calcium salt, and the purity is not less than 95%; Preferably, the magnesium source in step (1) comprises a soluble magnesium salt, and the purity is not less than 95%; Preferably, the silicon source in step (1) comprises silicate, and the purity is not less than 95%; Preferably, the mass ratio of the calcium source, the magnesium source and the silicon source in step (1) is (1-2):(1-2):(2-3).

3. The preparation method according to claim 1 or 2, characterized in that: The pH of the precursor solution in step (1) is controlled to be 6-8.

4. The preparation method according to any one of claims 1 to 3, characterized in that The volume of the precursor solution in the step (2) in the high-pressure reactor does not exceed 2 / 3 of the volume of the high-pressure reactor; Preferably, the reaction time in step (2) is 6-12 hours.

5. The preparation method according to any one of claims 1 to 4, characterized in that: After the reaction in step (2) is completed, cooling, washing and drying are performed in sequence; Preferably, the cooling method includes natural cooling; Preferably, the drying time is 30-60 minutes; Preferably, the drying temperature is 80-120°C; Preferably, in the seed crystals obtained in step (2) for the simultaneous removal of calcium and silicon from wastewater, the purity of the calcium-containing component, calculated as CaO, is greater than 30%, and the purity of the silicon-containing component, calculated as SiO2, is greater than 30%.

6. A seed crystal for synchronously removing calcium and silicon from wastewater, characterized in that: The preparation is obtained by the preparation method according to any one of claims 1 to 5.

7. A nuclear crystal granulation process, characterized in that: The nuclear crystal granulation process is carried out using the seed crystals prepared by the preparation method according to any one of claims 1 to 5; The core crystal granulation process comprises: (1) filling the seed crystal into a nuclear crystal granulation reactor; (2) introducing calcium and silicon-containing wastewater and a crystal-inducing agent from the lower part of the nuclear crystal granulation reactor to make the seed crystal in a fluidized state; The calcium ions and silicate ions in the wastewater containing calcium and silicon react with the crystal inducing agent to form nuclei and grow on the surface of the seed crystal in the form of precipitation to form granules, thereby achieving purification of the wastewater containing calcium and silicon.

8. The core crystal granulation process according to claim 7, characterized in that: The core crystal granulation reactor comprises an outer cylinder and an inner cylinder, wherein the inner cylinder is suspended in the outer cylinder and is connected vertically; At least one feed pipe is provided at the lower end of the side wall of the outer cylinder and is located below the opening at the lower end of the inner cylinder for introducing calcium- and silicon-containing wastewater and a crystal-inducing agent; The upper end or top of the side wall of the outer cylinder is provided with a water outlet pipe for discharging recycled water; A granulation body discharge pipe is provided at the bottom of the outer cylinder for discharging the granulation body; Preferably, a tooth-shaped overflow weir is provided at the upper opening of the inner cylinder.

9. The core crystal granulation process according to claim 8, characterized in that: There are two feed pipes, which are located at the same level and arranged opposite to each other, one of which is used to introduce calcium and silicon-containing wastewater, and the other is used to introduce a crystal-inducing agent.

10. The core crystal granulation process according to claim 8 or 9, characterized in that: Step (1) The seed crystals are filled in the inner cylinder, and the filling height is 20-50% of the height of the inner cylinder; Preferably, the pH of the reaction system in step (2) is controlled to be 8.5-9.5; Preferably, an acid solution and / or an alkaline solution is used to control the pH of the reaction system; Preferably, the acid solution comprises sulfuric acid and / or hydrochloric acid; Preferably, the alkaline solution comprises sodium hydroxide solution and / or potassium hydroxide solution; Preferably, the concentration of the alkaline solution does not exceed 5 mol / L; Preferably, the crystal inducing agent in step (2) is introduced in the form of a solution, and the crystal inducing agent comprises sodium aluminate; Preferably, the core crystal granulation process comprises at least one core crystal granulation reactor; Preferably, when there are no less than two nuclear crystallization granulation reactors, a plurality of the nuclear crystallization granulation reactors are arranged in series, and the regenerated water obtained from the previous nuclear crystallization granulation reactor is used as the feed wastewater of the next nuclear crystallization granulation reactor.

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