Emulsification method for waste tributyl phosphate / kerosene pyrolysis incineration

Abstract

The present application relates to a kind of waste phosphoric acid tributylamine / kerosene pyrolysis incineration emulsification method, comprising: phosphorus solid agent, emulsifier, water are mixed uniformly to obtain lime milk, then TBP / OK waste liquid is added into lime milk and mixed uniformly, to obtain TBP / OK emulsified suspension;Wherein emulsifier is nonylphenol polyoxyethylene ether.Compared with prior art, the present application improves the processing efficiency of waste organic phase, reduces the input of time cost and labor cost, has greater economic benefit and environmental benefit.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of low-radioactivity organic waste liquid treatment, and relates to an emulsified suspension formula simulating waste tributyl phosphate / kerosene pyrolysis incineration and a preparation method thereof, in particular to an emulsified suspension formula simulating low-radioactivity organic waste liquid, i.e., tributyl phosphate / kerosene with a volume ratio of 55% to 65%, in a pyrolysis incineration process and a preparation method thereof. BACKGROUND

[0002] At present, the wet process in the Purex process is generally used for spent fuel reprocessing, the basic principle of which is to use tributyl phosphate (TBP) as an extractant, kerosene (OK) as a diluent, and nitric acid as a salting agent, and to separate uranium, plutonium and fission products one by one by using the different partition coefficients of the different valence states in the organic extractant and the aqueous phase. Therefore, in the co-decontamination unit, the uranium purification unit and the plutonium purification unit during the Purex process, radioactive waste organic solvent tributyl phosphate / kerosene (hereinafter referred to as "TBP / OK") will be generated.

[0003] At present, a large amount of radioactive waste TBP / OK generated during the operation of the spent fuel reprocessing plant is mainly treated by pyrolysis incineration technology at home and abroad. In order to avoid the corrosion of the equipment by the pyrolysis product P2O5 of TBP and H3PO4 generated by the reaction of P2O5 with water, CaO, Ca(OH)2 or Mg(OH)2 and other solid powders need to be added to the feed liquid, and the waste liquid is prepared into an emulsified suspension and then sent into a pyrolysis furnace for pyrolysis. The phosphorus-containing compounds generated by pyrolysis are converted into extremely difficultly soluble phosphates or pyrophosphates and separated from the reactor for secondary waste treatment. The pyrolysis gas and vaporized kerosene are further burned in an incinerator, and the exhaust gas is treated by a tail gas treatment system and then detected to meet the discharge standard.

[0004] In the process of pyrolysis incineration TBP / OK, the preparation of waste liquid into emulsion suspension is a key step. In 2017, China Nuclear Sichuan Environmental Protection Engineering Co., Ltd. independently developed a formula for simulating low-level organic waste liquid pyrolysis incineration suspension (Chinese patent CN105161154B), which contains 25%-30% calcium hydroxide as a phosphorus removal agent, 32%-40% emulsifier and 32%-40% deionized water, and needs to add magnesium carbonate as an additive. The stable time of the obtained emulsion suspension is 1.5 hours, and the viscosity is 1.24-1.46 mPa·S. However, the formula is suitable for TBP / OK with a volume ratio of 20%-30%, and the TBP content is relatively low. The stable time of the prepared suspension is 1.5 hours, which is relatively short. In addition, the waste source is mainly the waste organic phase of the waste TBP / OK generated by the co-decontamination separation unit after oil-water separation equipment. However, for the new pyrolysis incineration process of TBP / OK, the distillation residue of the waste TBP / OK generated by the two-stage vacuum distillation is mixed with the kerosene fraction generated by the vacuum distillation treatment, and then a high volume ratio of 55%-65% (v / v) TBP / OK is prepared. The formula is not applicable, which is manifested in that after the lime milk solution is added to the TBP / OK solution and stirred, the two phases cannot be mixed to form a stable suspension, and the water and oil phases can be separated within 10 minutes. SUMMARY

[0005] The purpose of the present application is to provide an emulsification method for waste tri-n-butyl phosphate / kerosene pyrolysis incineration, which solves the problem of poor emulsification stability in the emulsification process of TBP / OK suspension with high TBP content.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] An emulsification method for waste tri-n-butyl phosphate / kerosene pyrolysis incineration, comprising: mixing a phosphorus removal agent, an emulsifier and water uniformly to obtain lime milk, and then adding TBP / OK waste liquid into the lime milk and mixing uniformly to obtain TBP / OK emulsion suspension; wherein the emulsifier is nonylphenol polyoxyethylene ether.

[0008] Further, the emulsifier is nonylphenol polyoxyethylene ether NP-7.

[0009] Further, the phosphorus removal agent is calcium hydroxide.

[0010] Further, in the TBP / OK emulsion suspension, the mass content of the emulsifier is 3%-5%, and the mass content of water is 20%-30%.

[0011] Further, the preparation process of the lime milk comprises: slowly adding the emulsifier into water under stirring and stirring uniformly, then slowly adding the phosphorus fixing agent and stirring uniformly to obtain the lime milk.

[0012] Further, the stirring speed during the mixing of water and the emulsifier is 180-220 rpm, and the stirring time is 8-12 min.

[0013] Further, the stirring speed during the mixing of the phosphorus fixing agent is 280-320 rpm, and the stirring time is 12-18 min.

[0014] Further, the preparation process is carried out at room temperature.

[0015] Further, in the TBP / OK waste liquid, the volume percentage of tributyl phosphate is 55-65%, and the volume percentage of hydrogenated kerosene is 35-45%.

[0016] Further, the volume / mass ratio of the lime milk and the TBP / OK waste liquid is (1.5-1.8) mL:1 g.

[0017] Further, the emulsification process is carried out at room temperature.

[0018] Further, the mixing process of the TBP / OK waste liquid and the lime milk comprises:

[0019] After mixing the TBP / OK waste liquid and the lime milk, stirring is carried out at a speed of 240-260 rpm for 5-15 min; then the speed is increased to 280-320 rpm, and stirring is carried out for 12-18 min to obtain the TBP / OK emulsified suspension.

[0020] The present application provides a new formula for solving the problems of poor emulsification effect and short stable time of the TBP / OK emulsified suspension with high TBP content caused by the existing emulsifier formula, and the formula is suitable for preparing the TBP / OK suspension with a volume ratio of 55-65%, and the stable time of the suspension is more than 12 hours, which not only increases the volume ratio of TBP in the suspension that can be effectively treated, reduces the waste treatment amount in the pyrolysis incineration process, but also has great economic and environmental benefits.

[0021] Compared with the prior art, the present application has the following characteristics:

[0022] 1) Compared with the calcium hydroxide suspension prepared in the invention of CN105161154B, the calcium hydroxide suspension prepared in the invention contains 10%~15% of the solid phosphorus agent calcium hydroxide, 3%~5% of the emulsifier and 20%~30% of the deionized water by mass ratio, and does not need to add additives. The invention has greater economic and environmental benefits while achieving the same emulsification effect;

[0023] 2) The invention proposes a new formula, which is suitable for preparing the emulsified suspension of 55%~65% high volume ratio of waste TBP / OK, improves the volume ratio of TBP in the treated waste source item, reduces the amount of solid phosphorus agent, emulsifier and deionized water, and does not need to add additives, greatly reducing the amount of waste treatment in the pyrolysis incineration process. After measurement, the emulsion time of the finally prepared suspension is <2h, the viscosity is about 80.68 mPa·S, and the phase separation time is >50h, which meets the requirements of the related process indicators: emulsion time <4h, viscosity ≤130 mPa·S, and phase separation time ≥12h, and meets the process requirements;

[0024] 3) The invention improves the treatment efficiency of waste organic phase, reduces the investment of time cost and labor cost, and has greater economic and environmental benefits. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The flow chart of the emulsification method for waste tri-n-butyl phosphate / kerosene pyrolysis incineration in the invention. DETAILED DESCRIPTION

[0026] The invention will be described in detail below with reference to the drawings and specific embodiments.

[0027] An emulsification method for waste tri-n-butyl phosphate / kerosene pyrolysis incineration, as shown in Figure 1 , includes:

[0028] S1: Preparation of lime milk solution:

[0029] Under the condition of stirring at 180~220 rpm, the emulsifier is slowly added to the water and continues to stir for 8~12 min, and then the speed is increased to 280~320 rpm, the solid phosphorus agent is slowly added and continues to stir for 12~18 min, to obtain the lime milk solution;

[0030] In some specific embodiments, the solid phosphorus agent is calcium hydroxide, which can meet the preparation requirements by using industrial pure grade, and the calcium to phosphorus ratio of the amount is preferably 1.2~1.4;

[0031] In some specific embodiments, the emulsifier used is a surfactant. Experiments were carried out on a series of surfactants such as SDBS, AES, OP-4, OP-7, NP-7, NP-10, etc. The results show that SDBS, AES, OP-4, OP-7 emulsifiers cannot be prepared into emulsion suspensions, and NP-10 emulsifier cannot be used to carry out experiments because it coagulates into a lump when added to water under laboratory room temperature (~ 15℃). Only NP-7 emulsifier can be prepared into emulsion suspensions that meet the technical indicators under laboratory room temperature (~ 15℃).

[0032] The emulsifier used is a high molecular compound with a chemical formula of C 15 H 24 O(C2H4O) n It is a non-ionic surfactant, mainly used as an emulsifier, detergent, wetting agent, dispersant and defoaming agent; preferably nonylphenol polyoxyethylene ether, and further preferably nonylphenol polyoxyethylene ether NP-7;

[0033] In the lime milk, the mass content of the emulsifier is 10-15%, and the mass content of water is 50-60%; in some specific embodiments, no other additives need to be added to the lime milk solution;

[0034] S2: Preparation of TBP / OK emulsion

[0035] After mixing the TBP / OK waste liquid with the lime milk solution, stirring at a speed of 240-260 rpm for 5-15 min; then increase the speed to 280-320 rpm and stir for 12-18 min to obtain a TBP / OK emulsion suspension;

[0036] The volume-mass ratio of lime milk solution to TBP / OK waste liquid is (1.5-1.8) mL:1 g; the volume percentage content of tributyl phosphate in the TBP / OK waste liquid is 55-65%, and the volume percentage content of hydrogenated kerosene is 35-45%.

[0037] In some specific embodiments, the above process is carried out at room temperature (~ 15℃).

[0038] In some specific embodiments, the mass content of the emulsifier in the emulsion suspension prepared by mixing the TBP / OK waste liquid with the lime milk is 3-5%, and the mass content of water is 20-30%.

[0039] The prepared TBP / OK emulsion meets the following process technical indexes: first, the emulsion formation time of the suspension is less than or equal to 4 hours; second, the viscosity of the suspension is less than or equal to 130 mPa·S; third, the phase separation time of the suspension is greater than or equal to 12 hours; and fourth, the emulsion can be re-emulsified within 15 minutes after the phase separation of the suspension, and the phase separation time after the re-emulsification still meets the requirements.

[0040] The following examples are implemented on the basis of the above technical solutions of the present application, and give detailed implementation modes and specific operation processes, but the protection scope of the present application is not limited to the following examples.

[0041] In the following examples, simulated TBP / OK waste liquid is used instead of actual TBP / OK waste liquid, and the preparation method includes: respectively taking 600 mL of TBP and 400 mL of hydrogenated kerosene; adding 400 mL of hydrogenated kerosene into a container, starting magnetic stirring, adjusting the rotation speed to 100 rpm, then adding 600 mL of TBP into the container, maintaining the rotation speed at 100 rpm after mixing, and continuing stirring for 10 minutes to obtain the simulated TBP / OK waste liquid.

[0042] Example:

[0043] An emulsification method for waste tributyl phosphate / kerosene pyrolysis incineration, comprising:

[0044] S1: Preparation of lime milk solution:

[0045] Deionized water, calcium hydroxide, and emulsifier nonylphenol polyoxyethylene ether NP-7 are weighed. The deionized water is added to a container, an electric stirrer is placed in the container, the electric stirrer is started, and the rotation speed is adjusted to 200 rpm. The emulsifier is slowly added to the beaker containing the deionized water, and the stirring is continued at a rotation speed of 200 rpm for 10 minutes. The rotation speed is then adjusted to 300 rpm, and the weighed calcium hydroxide is slowly added. After the addition of the calcium hydroxide is completed, the stirring is continued at a rotation speed of 300 rpm for 15 minutes to ensure that the calcium hydroxide and the deionized water are completely mixed with the emulsifier, and a lime milk solution is obtained.

[0046] S2: Preparation of emulsified suspension:

[0047] The prepared simulated TBP / OK waste liquid is placed in a stirrer, the stirring is started, and the rotation speed is adjusted to 250 rpm. The lime milk is slowly added to the TBP / OK simulated liquid while stirring, and the stirring is continued at a rotation speed of 250 rpm for 10 minutes. Then, the rotation speed is adjusted to 300 rpm, and the stirring is continued for 10 minutes to prepare a uniform and stable emulsified suspension.

[0048] The above materials are according to the formula in Table 1, in the emulsion suspension component, the calcium to phosphorus ratio of calcium hydroxide to TBP is 1.25, the amount of deionized water is 23.90% of the total mass of the emulsion suspension formula, and the amount of emulsifier is 3.2% of the total mass of the emulsion suspension formula.

[0049] Performance measurement of emulsion suspension:

[0050] The prepared emulsion suspension was measured for performance, including emulsion formation time, viscosity and phase separation time, with the following test standards: first, emulsion suspension formation time ≤ 4h; second, emulsion suspension viscosity ≤ 130 mPa·S; third, emulsion suspension phase separation time ≥ 12h. The results are shown in Table 1.

[0051] Table 1

[0052]

[0053] As can be seen from the table, the emulsion suspension prepared in this embodiment has an emulsion formation time < 2h, a viscosity of 80.68 mPa·S, and a phase separation time > 20h. After phase separation occurs, stirring for 15 minutes can completely restore the properties, meeting the process technical indicators of TBP / OK emulsion suspension in the pyrolysis incineration process.

[0054] The above description of the embodiments is to facilitate the understanding and use of the invention by those of ordinary skill in the art. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without having to go through creative labor. Therefore, the present application is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. An emulsification method for the pyrolysis and incineration of waste tributyl phosphate / kerosene, characterized in that, The method includes: mixing phosphorus fixative, emulsifier and water evenly to obtain lime milk, then adding TBP / OK waste liquid to lime milk and mixing evenly to obtain TBP / OK emulsion suspension; The emulsifier mentioned above is nonylphenol polyoxyethylene ether NP-7; The phosphorus-fixing agent is calcium hydroxide; The TBP / OK waste liquid contains 55-65% tributyl phosphate by volume and 35-45% hydrogenated kerosene by volume. The volume-to-mass ratio of the lime slurry to the TBP / OK waste liquid is (1.5~1.8) mL:1 g; In the TBP / OK emulsion suspension, the emulsifier content is 3%~5% by mass, and the water content is 20%~30% by mass.

2. The emulsification method for the pyrolysis and incineration of waste tributyl phosphate / kerosene according to claim 1, characterized in that, The preparation process of the lime slurry includes: While stirring, emulsifier is slowly added to water and stirred until homogeneous. Then, phosphorus fixative is slowly added and stirred until homogeneous to obtain lime milk.

3. The emulsification method for the pyrolysis and incineration of waste tributyl phosphate / kerosene according to claim 2, characterized in that, During the mixing process of water and emulsifier, the stirring speed is 180~220 rpm and the stirring time is 8~12 min.

4. The emulsification method for the pyrolysis and incineration of waste tributyl phosphate / kerosene according to claim 2, characterized in that, During the mixing process with the phosphorus fixative, the stirring speed is 280~320 rpm and the stirring time is 12~18 min.

5. The emulsification method for the pyrolysis and incineration of waste tributyl phosphate / kerosene according to claim 1, characterized in that, The mixing process of TBP / OK waste liquid and lime slurry includes: After mixing TBP / OK waste liquid with lime slurry, stir at 240~260 rpm for 5~15 min; then increase the speed to 280~320 rpm and stir for 12~18 min to obtain TBP / OK emulsion suspension.

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