A method for preparing calcium phosphate based on by-product ammonium chloride

Abstract

The application discloses a kind of calcium phosphate preparation methods based on by-product ammonium chloride, effectively reduce the generation of calcium sulfate and calcium fluoride solid waste, comprising the following steps: step S1, to 300-360 mass parts of by-product ammonium chloride solution containing fluorine impurities and phosphate radical is added fluoride removal agent, fluoride removal treatment is carried out, and fluoride removal after ammonium chloride solution and fluorine-containing residue are obtained;Step S2, the pH value of step S1 obtained after the defluorination of ammonium chloride solution is adjusted to neutral or weak alkaline;Step S3, to the solution after adjusting pH of step S2 is added calcium source, and reaction generates calcium phosphate precipitate;Step S4, solid-liquid separation, and further processing after obtaining calcium phosphate solid and ammonium chloride solution, the application novel structure, ingenious, simple and convenient operation, effectively realizes waste liquid resource utilization, improves the defluorination effect, speeds up flocculation rate, improves the recovery rate of by-product ammonium chloride, and high-purity calcium phosphate is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical production, and relates to a calcium phosphate preparation method based on byproduct ammonium chloride. BACKGROUND

[0002] In the phosphorus chemical industry, fertilizer production and other industries, a large amount of ammonium chloride solution containing fluorine ions (F - ) and phosphate ions (PO4 3- ) is often by-produced. The resource treatment of such waste liquid faces two major problems:

[0003] 1. Fluorine impurities are difficult to remove deeply: the traditional process adopts direct addition of calcium salt (such as calcium chloride) to precipitate fluorides, but will simultaneously generate calcium sulfate (CaSO4) and calcium fluoride (CaF2) mixed solid waste, which has high treatment cost and is easy to cause environmental risk.

[0004] 2. Phosphate resources are wasted: the phosphate in the waste liquid is prematurely combined with calcium ions and wrapped in low-value solid waste, and cannot be directly recovered as high-purity calcium phosphate.

[0005] In view of the prior art, the current improved process mostly focuses on a single problem in fluorine removal or calcium phosphate preparation. In the fluorine removal process, polyaluminum chloride (PAC) or activated alumina adsorption is mostly used, but the efficiency is low when treating high-salinity ammonium chloride solution, resulting in more fluorine residues; in the recovery and preparation process of calcium phosphate, additional introduction of phosphate ions is required, resulting in doubled cost.

[0006] Therefore, a calcium phosphate preparation method capable of simultaneously achieving fluorine removal and efficient recovery of calcium phosphate is needed to reduce the generation of solid waste and improve resource value. SUMMARY

[0007] In view of the above problems, the application provides a calcium phosphate preparation method based on byproduct ammonium chloride, which solves the problems in the prior art.

[0008] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0009] A calcium phosphate preparation method based on byproduct ammonium chloride, comprising the following steps:

[0010] Step S1, adding a fluorine removal agent to 300-360 parts by mass of byproduct ammonium chloride solution containing fluorine impurities and phosphate, and performing fluorine removal treatment to obtain fluorine-removed ammonium chloride solution and fluorine-containing residue;

[0011] Step S2, adjusting the pH value of the fluorine-removed ammonium chloride solution obtained in step S1 to neutral or weak alkaline;

[0012] Step S3, adding a calcium source to the solution after pH adjustment in step S2 to generate calcium phosphate precipitate.

[0013] Step S4, solid-liquid separation, to obtain calcium phosphate solid and further treated ammonium chloride solution.

[0014] Preferably, in the step S1, the adding amount of the defluorination agent is 0.60-0.72 mass parts.

[0015] In the step S3, the adding amount of the calcium source is 6.70-8.05 mass parts.

[0016] Preferably, in the step S1, the defluorination agent comprises a metal salt and an organic polymer, the metal salt is selected from one or more of iron salt, aluminum salt and manganese salt; the organic polymer is selected from one or more of polyaluminum chloride, polyacrylamide and humic acid.

[0017] Preferably, in the step S1, the defluorination treatment comprises stirring, precipitation and filtration.

[0018] Preferably, in the step S2, the pH value is adjusted to a range of 7-8.

[0019] Preferably, in the step S3, the calcium source is calcium chloride.

[0020] Preferably, the calcium chloride is subjected to drying treatment before use, the drying treatment is performed at a temperature of 250-300℃ for 100-140 minutes.

[0021] Preferably, the stirring speed in the step S1 is 200-300r / min.

[0022] Preferably, the calcium phosphate solid obtained in the step S4 is subjected to water washing treatment for 2-4 times.

[0023] Preferably, in the step S1, the defluorination agent is composed of the following components in mass parts:

[0024] Humic acid: 25-35 parts, iron chloride: 8-12 parts, manganese chloride: 15-25 parts, polyaluminum chloride: 35-45 parts, polyacrylamide: 1 part.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] The present application realizes resource utilization of waste liquid, improves defluorination effect, accelerates flocculation speed, improves recovery rate of by-product ammonium chloride, and obtains high-purity calcium phosphate by the reaction mode of first removing fluorine and then generating calcium phosphate salt. DETAILED DESCRIPTION

[0027] With reference to the specific embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0028] With reference to the specific embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0029] Embodiment 1

[0030] Take 320 parts by mass of a by-product ammonium chloride solution of a chemical plant, the ammonium chloride solution containing F - 0.5%, PO4 3- 1.2 mol / L, add 0.66 parts by mass of a fluorine removal agent, the fluorine removal agent containing, by mass fraction: humic acid 30 parts, FeCl3 10 parts, MnCl2 20 parts, polyaluminum chloride 40 parts, and polyacrylamide 1 part, stir at 250 r / min for 30 min, stand for 1 h, and filter to obtain a fluorine-removed solution (F - ≤0.008%) and a fluorine-containing residue.

[0031] Adjust the pH of the filtrate to 7.5 with ammonia water, add 7.4 parts by mass of aluminum chloride CaCl2 dried at 280℃ for 120 min, and after 1 h of reaction, perform suction filtration.

[0032] Wash the calcium phosphate filter cake with water for 3 times, and dry at 105℃ to obtain a finished product of calcium phosphate; the filtrate is a fluorine-removed ammonium chloride solution.

[0033] Embodiment 2

[0034] On the basis of Embodiment 1, the composition of the fluorine removal agent is adjusted, and the fluorine removal agent is used in the following proportions: humic acid 30 parts, FeCl3 8 parts, MnCl2 25 parts, PAC 35 parts, and PAM 1 part, and the other step parameters are the same as in Embodiment 1.

[0035] Embodiment 3

[0036] Take 320 parts by mass of a by-product ammonium chloride solution of a chemical plant, the ammonium chloride solution containing F - 0.5%, PO4 3- 1.2 mol / L, add 0.66 parts by mass of a fluorine removal agent, the fluorine removal agent containing, by mass fraction: humic acid 30 parts, FeCl3 10 parts, MnCl2 20 parts, polyaluminum chloride 40 parts, and polyacrylamide 1 part, stir at 250 r / min for 30 min, stand for 1 h, and filter to obtain a fluorine-removed solution (F - ≤0.008%) and a fluorine-containing residue.

[0037] The filtrate was adjusted to pH 7.5 with ammonia water, 7.4 parts by mass of aluminum chloride CaCl2 dried at 300°C for 100 min was added, and the reaction was carried out for 1 h before filtration.

[0038] The calcium phosphate filter cake was washed with water twice and dried at 105°C to obtain the finished product of calcium phosphate; the filtrate was the ammonium chloride solution after defluorination.

[0039] Example 4

[0040] On the basis of Example 1, the composition of the calcium source was adjusted, and the calcium source was replaced by calcium nitrate (Ca(NO3)2) instead of calcium chloride, with an amount of 8.9 parts by mass equivalent to the molar amount of calcium ions, and the other step parameters were the same as in Example 1.

[0041] Example 5.1

[0042] On the basis of Example 1, the mass fraction of the ammonium chloride solution was adjusted to 300, the mass fraction of the defluorination agent was adjusted to 0.60 parts, the mass fraction of CaCl2 was adjusted to 6.70 parts, and the other step parameters were the same.

[0043] Example 5.2

[0044] On the basis of Example 1, the mass fraction of the ammonium chloride solution was adjusted to 360, the mass fraction of the defluorination agent was adjusted to 0.72 parts, the mass fraction of CaCl2 was adjusted to 8.05 parts, and the other step parameters were the same.

[0045] Comparative Example 1

[0046] 320 parts by mass of the same batch of ammonium chloride solution as in Example 1 was taken from a certain chemical plant as a by-product, which contained F - 0.5%, PO4 3- 1.2 mol / L) in the ammonium chloride solution, 7.4 parts by mass of CaCl2 was directly added, generating a gray-white solid waste (CaSO4 and CaF2), and the filtrate (F - 0.38%) and solid waste (CaSO4 and CaF2 mixture) were obtained by filtration. To the filtrate (F - 0.38%) after filtration, 0.66 parts by mass of a defluorination agent (humic acid 30 parts, FeCl3 10 parts, MnCl2 20 parts, PAC 40 parts, and PAM 1 part) was added, stirred at 250 r / min for 30 min, and allowed to stand for 1 h before filtration to obtain a low-fluorine ammonium chloride solution (without the generation of calcium phosphate).

[0047] Comparative Example 2

[0048] On the basis of Example 1, the formula and mass ratio of the defluorination agent were changed to humic acid 15 parts and polyaluminum chloride 50 parts.

[0049] According to the tests of the products of the above examples and comparative examples, the following table was obtained:

[0050] Experimental group fluorine residual rate total amount of solid waste (g / 320 parts of solution) Calcium phosphate purity (P205% / CaO%) calcium phosphate output Example 1 0.007% 12.8 41.2% / 54.1% high purity Example 2 0.006% 12.5 41.5% / 54.3% high purity Example 3 0.009% 13.2 40.1% / 53.2% up to standard Example 4 0.021% 13.5 38.7% / 51.0% low purity Example 5.1 0.010% 11.9 (300 parts of solution) 40.1% / 53.0% high purity Example 5.2 0.008% 14.1 (360 parts of solution) 40.3% / 53.2% high purity Comparative Example 1 0.092% 89.5 not generated no output Comparative Example 2 0.12% 15.0 not generated no output

[0051] In combination with the above-mentioned embodiments, comparative examples, and test results, the following can be obtained:

[0052] By way of example 1 as the main technical solution of the present application, compared with the traditional process comparative example 1, the pre-positioned fluorine removal process of the present application avoids the generation of calcium sulfate (CaSO4) and calcium fluoride (CaF2) mixed solid waste. The total amount of solid waste of the technical solution of the present application through example 1 is only 12.8g, while the total amount of solid waste of the traditional process comparative example 1 is 89.5g. Through the technical solution of the present application, the amount of solid waste is reduced;

[0053] In example 2, compared with example 1, the specific components of the fluorine removal agent are specifically limited, verifying the defluorination effect of the fluorine removal agent in the technical solution of the present application;

[0054] In example 3, compared with example 1, the stirring speed, calcium chloride drying parameters and water washing times are changed, but the test results show that it is not as good as example 1;

[0055] In example 4, compared with example 1, the calcium source is changed to calcium nitrate, and the results show that the introduction of impurity anions by calcium nitrate leads to a decrease in purity and an increase in solution ion concentration;

[0056] Example 5.1 and example 5.2 are compared, and the results show that in 300-360 parts by mass of by-product ammonium chloride solution, the process effect of the present application is relatively stable;

[0057] Comparative example 1 is a traditional process, compared with example 1, it does not pre-position fluorine removal, resulting in a sharp increase in solid waste and low product purity;

[0058] In comparative example 2, compared with example 1, the ratio of the fluorine removal agent is changed, and the results show that when humic acid is less than 25 parts, the defluorination efficiency and flocculation performance decrease sharply.

[0059] The present application has a clever design, is simple and convenient to operate, effectively reduces the generation of calcium sulfate and calcium fluoride solid waste, realizes the resource utilization of waste liquid, improves the defluorination effect, speeds up the flocculation speed, improves the recovery rate of by-product ammonium chloride, and obtains high-purity calcium phosphate.

[0060] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for part of the technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent substitution, improvement, etc. made shall be included in the protection scope of the present application.

Claims

1. A method for preparing calcium phosphate based on byproduct ammonium chloride, characterized in that: Includes the following steps: Step S1: Add a defluorinating agent to 300-360 parts by mass of a by-product ammonium chloride solution containing fluorine impurities and phosphate ions to perform defluorination treatment, and obtain a defluorinated ammonium chloride solution and fluorine-containing residue. The defluorinating agent consists of the following components in parts by weight. composition: Humic acid: 25-35 parts, ferric chloride: 8-12 parts, manganese chloride: 15-25 parts, polyaluminum chloride: 35-45 parts, polyacrylamide: 1 part; Step S2: Adjust the pH of the defluorinated ammonium chloride solution obtained in step S1 to neutral or weakly alkaline. Step S3: Add a calcium source to the solution after adjusting the pH in step S2, and react to form calcium phosphate precipitate; Step S4: Solid-liquid separation to obtain calcium phosphate solid and ammonium chloride solution after further processing.

2. The method for preparing calcium phosphate based on by-product ammonium chloride according to claim 1, characterized in that: In step S1, the amount of the defluorinating agent added is 0.60-0.72 parts by mass; In step S3, the amount of calcium source added is 6.70-8.05 parts by mass.

3. The method for preparing calcium phosphate based on by-product ammonium chloride according to claim 1, characterized in that: In step S1, the defluorination process includes stirring, precipitation, and filtration.

4. The method for preparing calcium phosphate based on by-product ammonium chloride according to claim 1, characterized in that: In step S2, the pH value is adjusted to a range of 7-8.

5. The method for preparing calcium phosphate based on by-product ammonium chloride according to claim 1, characterized in that: In step S3, the calcium source is calcium chloride.

6. The method for preparing calcium phosphate based on by-product ammonium chloride according to claim 5, characterized in that: The calcium chloride is dried before use at a temperature of 250-300℃ for 100-140 minutes.

7. The method for preparing calcium phosphate based on by-product ammonium chloride according to claim 1, characterized in that: The stirring speed in step S1 is 200-300 r / min.

8. The method for preparing calcium phosphate based on by-product ammonium chloride according to claim 1, characterized in that: The calcium phosphate solid obtained in step S4 is washed with water 2-4 times.