Neutralization method deacidification process for resource utilization of sodium chloride

Abstract

The application discloses a neutralization method acid-removing process for resource utilization of sodium chloride, and ammonia gas, liquid ammonia or ammonia water is introduced into carbonized mother liquor; preferably, the ammonia gas is introduced during the process of cold separation and crystallization of the carbonized mother liquor; the ammonia gas introduced during the process of cold separation and crystallization plays a stirring role, can inhibit the rapid growth and agglomeration of ammonium chloride crystals to carry liquid, and further cause the reduction of purity of ammonium chloride, and is beneficial to the precipitation of a large amount of fine and high-purity ammonium chloride crystals; after the ammonia gas enters the carbonized mother liquor, the ammonia gas reacts with ammonium bicarbonate to produce ammonium carbonate, on the one hand, sodium bicarbonate is avoided to be precipitated during the process of cold separation and salting-out crystallization, and on the other hand, the concentration of ammonium ions in the carbonized mother liquor is improved, and more ammonium chloride crystals can be precipitated.

Description

Technical Field

[0001] This invention relates to the field of sodium chloride alkali production technology. Specifically, it relates to a neutralization deacidification process for the resource utilization of sodium chloride. Background Technology

[0002] Chemical processes generate large quantities of sodium chloride byproducts or products with sodium chloride as the main component annually. The resource recycling of sodium chloride is of great significance for reducing enterprise operating costs and protecting the environment. The production of sodium bicarbonate / sodium carbonate products from sodium chloride as raw material, with the byproduct of ammonium chloride fertilizer, makes good use of the Na and Cl components. The resulting sodium bicarbonate / sodium carbonate products are relatively easy to recycle within enterprises. Compared to landfill and high-temperature treatment methods, this approach is environmentally friendly, industrially feasible, and technologically mature and simple, gradually becoming one of the important pathways for the resource recycling of sodium chloride.

[0003] In existing industrial processes, the production of sodium bicarbonate / sodium carbonate from sodium chloride mainly includes the ammonia-soda process and the combined alkali production process. When using solid-phase sodium chloride as a raw material in the ammonia-soda process, stricter environmental standards make it difficult to economically treat calcium chloride-containing wastewater in new plants, and chloride ions are not effectively utilized. The ammonium chloride byproduct obtained from the combined alkali production process has low purity and fine particles, making it difficult to use for industrial applications. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide an energy-saving and emission-reducing neutralization deacidification process for the resource utilization of sodium chloride.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A neutralization deacidification process for the resource utilization of sodium chloride involves introducing ammonia gas, liquid ammonia, or ammonia water into the carbonization mother liquor.

[0007] The above-mentioned neutralization deacidification process for the resource utilization of sodium chloride involves introducing ammonia gas during the cold crystallization of the carbonization mother liquor. The introduction of ammonia gas during the cold crystallization process acts as a stirrer, inhibiting the rapid growth and agglomeration of ammonium chloride crystals, which would otherwise carry liquid residues and reduce the purity of ammonium chloride. This process facilitates the precipitation of a large number of fine and high-purity ammonium chloride crystals. After entering the carbonization mother liquor, the ammonia gas reacts with ammonium bicarbonate to produce ammonium carbonate. This process avoids the precipitation of sodium bicarbonate during cold crystallization and / or salting out, and also increases the concentration of ammonium ions in the carbonization mother liquor, promoting the precipitation of even more ammonium chloride crystals.

[0008] The above-mentioned neutralization deacidification process for the resource utilization of sodium chloride has an initial temperature of 30-55℃ for the carbonization mother liquor and an endpoint temperature of 5-10℃ for the cold precipitation crystallization of the carbonization mother liquor.

[0009] In the above-mentioned neutralization deacidification process for the resource utilization of sodium chloride, the temperature of ammonia gas is 2-5°C lower than the final temperature of the carbonization mother liquor for cold crystallization. If the ammonia temperature is too low, it is easy to cause excessive local temperature drop in the carbonization mother liquor, which will result in the precipitated ammonium chloride crystals being entrained with the liquid, and may also cause sodium bicarbonate crystals to precipitate together with the ammonium chloride crystals. If the ammonia temperature is too high, it is not conducive to the precipitation of a large number of fine ammonium chloride crystals to serve as crystal nuclei, and the final ammonium chloride crystals have an uneven particle size distribution.

[0010] The above-mentioned neutralization deacidification process for the resource utilization of sodium chloride utilizes carbonization mother liquor to heat liquid ammonia, thereby vaporizing the liquid ammonia into ammonia gas.

[0011] In the above-mentioned neutralization deacidification process for the resource utilization of sodium chloride, the concentration of bicarbonate in the carbonation mother liquor is 45-100 g / L.

[0012] The above-mentioned neutralization deacidification process for the resource utilization of sodium chloride involves introducing ammonia gas into the carbonation mother liquor in an amount that is 1.0 to 1.5 times the total amount of bicarbonate ions in the carbonation mother liquor. This process can completely convert bicarbonate ions in the carbonation mother liquor into carbonate ions, preventing the precipitation of sodium bicarbonate during cold precipitation and / or salting-out crystallization.

[0013] In the above-mentioned neutralization deacidification process for the resource utilization of sodium chloride, the time from the start of cold crystallization of the carbonization mother liquor to the end of cold crystallization of the carbonization mother liquor is T, and the time period for introducing ammonia gas into the carbonization mother liquor is 0-0.75T. Stopping the introduction of ammonia gas in the later stage of cold crystallization of the carbonization mother liquor is conducive to the growth of fine ammonium chloride crystals into coarse ammonium chloride crystals, thereby improving the filtration and separation efficiency. If the time for introducing ammonia gas into the carbonization mother liquor is too short, such as the time period for introducing ammonia gas into the carbonization mother liquor is 0-0.5T, then not enough fine ammonium chloride crystals will be formed in the carbonization mother liquor, which is not conducive to obtaining ammonium chloride crystals with uniform particle distribution.

[0014] The technical solution of the present invention has achieved the following beneficial technical effects: by introducing ammonia into the carbonization mother liquor, the purpose of deacidification can be achieved without heating the carbonization mother liquor, thus saving energy; moreover, no carbon dioxide gas will be released during the deacidification process. Detailed Implementation

[0015] Example 1

[0016] The initial temperature of the carbonization mother liquor was 35℃, the final temperature of the cold crystallization of the carbonization mother liquor was 5℃, and the concentration of bicarbonate in the carbonization mother liquor was 82.3 g / L.

[0017] Liquid ammonia is heated using carbonization mother liquor to vaporize it into ammonia gas. Ammonia gas is then introduced during the cold crystallization process of the carbonization mother liquor. The temperature of the ammonia gas is 0℃. The total amount of ammonia gas introduced into the carbonization mother liquor is 1.0 times the total amount of bicarbonate ions in the carbonization mother liquor. The time from the start of cold crystallization of the carbonization mother liquor to the end of cold crystallization is T. The time period for introducing ammonia gas into the carbonization mother liquor is 0-0.75T.

[0018] After cold crystallization, the concentration of bicarbonate in the mother liquor was 0.0 g / L, and the purity of the precipitated ammonium chloride crystals was 99.20%, meeting the requirements for qualified industrial ammonium chloride in GB / T 2946-2018.

[0019] Example 2

[0020] The initial temperature of the carbonization mother liquor was 55℃, the final temperature of the cold crystallization of the carbonization mother liquor was 10℃, and the concentration of bicarbonate in the carbonization mother liquor was 95 g / L.

[0021] The liquid ammonia is heated by heating the carbonization mother liquor, causing the liquid ammonia to vaporize into ammonia gas. Ammonia gas is then introduced during the cold crystallization process of the carbonization mother liquor. The temperature of the ammonia gas is 5℃. The total amount of ammonia gas introduced into the carbonization mother liquor is 1.1 times the total amount of bicarbonate ions in the carbonization mother liquor. The time from the start of cold crystallization of the carbonization mother liquor to the end of cold crystallization is T. The time period for introducing ammonia gas into the carbonization mother liquor is 0-0.75T.

[0022] After the cold crystallization was completed, the concentration of bicarbonate in the mother liquor was 0.0 g / L, and the purity of the precipitated ammonium chloride crystals was 99.15%, which met the requirements for qualified industrial ammonium chloride in GB / T 2946-2018.

[0023] Comparative Example

[0024] The initial temperature of the carbonization mother liquor was 55℃, the final temperature of the cold crystallization of the carbonization mother liquor was 10℃, and the concentration of bicarbonate in the carbonization mother liquor was 90 g / L. The carbonization mother liquor used for alkali production was then subjected to cold crystallization.

[0025] After cold crystallization, the concentration of bicarbonate in the mother liquor was 61 g / L, the purity of the precipitated ammonium chloride crystals was 81.50%, and the nitrogen content was 21.33%, which did not meet the requirements for qualified agricultural ammonium chloride in GB / T 2946-2018.

[0026] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A neutralization deacidification process for the resource utilization of sodium chloride, characterized in that, Ammonia gas is introduced into the carbonization mother liquor. When ammonia gas is introduced during the cold crystallization process of the carbonization mother liquor: the initial temperature of the carbonization mother liquor is 30-55℃, and the final temperature of the cold crystallization of the carbonization mother liquor is 5-10℃; the temperature of the ammonia gas is 2-5℃ lower than the final temperature of the cold crystallization of the carbonization mother liquor; the time from the start of cold crystallization of the carbonization mother liquor to the end of cold crystallization of the carbonization mother liquor is T, and the time period for introducing ammonia gas into the carbonization mother liquor is 0-0.75T.

2. The neutralization deacidification process for the resource utilization of sodium chloride according to claim 1, characterized in that, The concentration of bicarbonate in the carbonation mother liquor is 45–100 g / L.

3. The neutralization deacidification process for the resource utilization of sodium chloride according to claim 1, characterized in that, The total amount of ammonia gas introduced into the carbonization mother liquor is 1.0 to 1.5 times the total amount of bicarbonate ions in the carbonization mother liquor.