Method for changing color of industrial sodium sulfide by adopting ferrous sulfate

Abstract

The invention relates to the technical field of sodium sulfide preparation, in particular to a method for changing the color of industrial sodium sulfide through ferrous sulfate. Comprising the following steps: S1, pumping a sodium sulfide solution into an evaporator for evaporation and concentration; s2, concentrating sodium sulfide until the content meets the requirement of a fixed product, analyzing the Fe content of the sodium sulfide, measuring the specific gravity, and calculating the total mass; s3, pumping the concentrated sodium sulfide semi-finished product in S2 into a reaction tank, and starting stirring; s4, according to specified requirements, calculating the addition amount of FeSO4 through the data in the S2; s5, in the stirring process in the S3, continuously adding FeSO4 into the tank, and after addition is completed, continuously stirring until complete reaction and uniform mixing are realized; and S6, feeding the uniformly mixed sodium sulfide solution in the step S5 into a flaking and packaging unit for treatment to obtain a high-iron and high-red industrial sodium sulfide product. According to the method for changing the color of the industrial sodium sulfide by adopting the ferrous sulfate, a technology for preparing a high-iron dark red product by adding the ferrous sulfate is utilized, and the product requirements of customers on different iron contents and colors are met.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium sulfide preparation, and particularly to a method for changing the color of industrial sodium sulfide by using ferrous sulfate. Background Art

[0002] Currently, the main production process of industrial sodium sulfide is prepared by carbon reducing sodium sulfate. Most of the production equipment is made of iron and related products. Under the corrosion of sodium sulfide liquid, iron ions enter the product. Industrial sodium sulfide shows different degrees of red due to different Fe ion contents. When enterprises face the complex and changeable market, they cannot meet the needs of customers for sodium sulfide products of different colors according to the conventional production process. Summary of the Invention

[0003] The technical solution of the present invention provides a solution significantly different from the prior art for the technical problem that the solution of the prior art is too single. To overcome the above defects of the prior art, the present invention provides a method for changing the color of industrial sodium sulfide by using ferrous sulfate, aiming to solve the problems raised in the above background art.

[0004] To achieve the above object, the present invention provides a method for changing the color of industrial sodium sulfide by using ferrous sulfate, which includes the following steps:

[0005] S1: Pump the sodium sulfide solution into an evaporator for evaporation and concentration;

[0006] S2: Concentrate the sodium sulfide to meet the required content of the customized product, analyze its Fe content, measure the specific gravity, and calculate the total mass;

[0007] S3: Pump the concentrated semi-finished sodium sulfide in S2 into a reaction tank and start stirring;

[0008] S4: Calculate the addition amount of FeSO4 according to the specified requirements through the data in S2;

[0009] S5: During the stirring process in S3, continuously add FeSO4 into the tank. After the addition is completed, continue to stir until it completely reacts and is evenly mixed;

[0010] S6: Send the evenly mixed sodium sulfide solution in S5 to a tablet-making and packaging unit for treatment to obtain an industrial sodium sulfide product with high iron and high red color.

[0011] The reaction mechanism of this method is:

[0012] When sodium sulfide is in a solution state, water molecules ionize OH -It is strongly alkaline. When FeSO4 additive is added, FeS and Fe(OH)2 precipitates will be rapidly formed. The solubility of the black precipitate FeS is less than that of Fe(OH)2. Due to the principle of preferential precipitation for the ions entering the solution, that is, if there are several ions in a solution that can form precipitates with the added reagent, the substance with a smaller solubility (strictly speaking, solubility product) will precipitate first. So, the black precipitate is formed first, and then the Fe 2+ rapidly combines with the hydrolyzed hydroxide ions in the solution to form Fe(OH)2 precipitate. Also, because this reaction is irreversible, ferrous sulfide rapidly dissolves to form more ferrous ions that combine with hydroxide ions, thus producing a milky white precipitate. Both the reactant FeS and the theoretical product Fe(OH)2 are precipitates. Checking the solubility product table of substances, at room temperature,

[0013] Ksp(FeS) =

Fe 2+

S 2-

[0014] When the precipitation equilibrium is reached, in the solution

[0015]

Fe 2+

S 2-

[0016] However, Ksp(Fe(OH)2) =

Fe 2+

OH -

[0017]

OH -

[0018] Then lg

OH -

[0019] pH = 14 - 3.25 = 10.75

[0020] Therefore, when pH < 10.75, there is no reaction; when pH > 10.75, there is a reaction.

[0021] During the reaction, the reaction equation of ferrous sulfide and sodium hydroxide is FeS + 2NaOH = Na2S + Fe(OH)2. Since the white precipitate Fe(OH)2 is unstable and will soon be oxidized by oxygen in the air to form reddish-brown Fe(OH)3, the reaction equation is:

[0022] 4Fe(OH)2 + O2 + 2H2O = 4Fe(OH)3

[0023] Therefore, the higher the content of Fe(OH)3, the redder the color of the finished product.

[0024] Preferably, the content of the sodium sulfide solution in S1 is 28% - 30%.

[0025] The sodium sulfide solution is easily oxidized in the air to form products such as sodium thiosulfate and sodium sulfite. However, the concentration range of 28% - 30% can slow down the negative impact brought by excessive oxidation, maintain the activity of the agent while reducing the risk of deterioration. This concentration range not only meets the demand for the effective component of sodium sulfide in industrial production but also avoids the possible waste of resources or operational complexity caused by high-concentration solutions.

[0026] Preferably, the content of the concentrated sodium sulfide in S2 is more than 60%.

[0027] Sodium sulfide with a concentration of 60% usually exists in the form of flaky solids (commonly known as "yellow flake caustic soda"). Compared with the liquid state, the solid product is easier to store and has lower transportation costs. And at this time, the solution viscosity is appropriate, which is convenient for tablet making or filling, while reducing the energy consumption of subsequent processing.

[0028] Preferably, the reaction tank in S3 is made of stainless steel, and a stirring mechanism is preset on the reaction tank made of stainless steel.

[0029] Stainless steel (such as SUS304, SUS316L, etc.) contains chromium and nickel elements and shows excellent corrosion resistance to chemical substances (such as acids, alkalis, oxidants, etc.) and reaction products (such as sulfide and hydrogenation products). At the same time, the processing and adaptation of the reaction tank made of stainless steel are flexible. The shape of the tank body, the stirring form (anchor type, frame type, etc.) and the capacity (100L to 25000L) can be customized according to the process requirements, and the applicable scenarios are wide.

[0030] Preferably, the FeSO4 in S4 is a by-product of titanium dioxide production, and the content is more than 98%.

[0031] High-purity FeSO4 (≥98%) has extremely low impurity content, which can reduce the interference of side reactions and improve its accuracy and controllability in chemical reactions. Therefore, it has wide industrial applicability. In the fields of pharmaceuticals, catalyst preparation, etc., high-purity FeSO4 meets strict hygiene and process requirements, avoiding the impact of impurity introduction on product quality.

[0032] Preferably, the stirring time of FeSO4 and the concentrated sodium sulfide semi-finished product in S5 is 20 minutes.

[0033] Stirring FeSO4 and the concentrated sodium sulfide semi-finished product for 20 minutes can improve the system stability by promoting the completion of the reaction.

[0034] Preferably, the tablet making and packaging unit in S6 is an integrated fully automated structure.

[0035] The tablet production and packaging unit includes a tablet machine and a quantitative packaging machine. Both the tablet machine and the quantitative packaging machine adopt the existing fully automatic structures on the market to form an integrated function.

[0036] The beneficial effects of the present invention are as follows:

[0037] When the present invention is in use, it effectively utilizes the by-product ferrous sulfate of titanium dioxide production enterprises as an additive, realizing the reuse of waste and having environmental protection significance. Using ferrous sulfate [FeSO4] as an additive has a lower cost than iron oxide red [Fe2O3]; and no toxic or harmful gases are generated during the addition of ferrous sulfate [FeSO4], and the additive itself is also relatively safe; this reflects the safety during the use of this method. Thus, in the industrial sodium sulfide market, it fills the demand gap for high-iron and high-red products of some customers, and is thus conducive to popularization and use. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following-described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 It is a control chart for the color control of industrial sodium sulfide in the specific implementation manner of the present invention;

[0040] Figure 2 It is a process schematic diagram of the specific implementation manner of the present invention. Specific Embodiment

[0041] The following will describe in detail the embodiments of the present invention. The examples of the embodiments are shown in the drawings. Preferably, the same or similar reference numerals are used throughout to represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0042] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. In addition, in the description of the present invention, the meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0043] Please refer to Figures 1 to 2 , the present invention provides a method for changing the color of industrial sodium sulfide by using ferrous sulfate, which includes the following steps:

[0044] S1: Pump the sodium sulfide solution into an evaporator for evaporation and concentration;

[0045] S2: Concentrate the sodium sulfide until it meets the required content of the customized product, analyze its Fe content, measure the specific gravity, and calculate the total mass;

[0046] S3: Pump the semi-finished sodium sulfide concentrated in S2 into a reaction tank and start stirring;

[0047] S4: Calculate the addition amount of FeSO4 according to the specified requirements based on the data in S2;

[0048] S5: Continuously add FeSO4 into the tank during the stirring process in S3. After the addition is completed, continue stirring until it completely reacts and is evenly mixed;

[0049] S6: Send the evenly mixed sodium sulfide solution in S5 to a tablet-making and packaging unit for processing to obtain an industrial sodium sulfide product with high iron and high red color.

[0050] The content of the sodium sulfide solution in S1 is 28% - 30%.

[0051] The content of the concentrated sodium sulfide in S2 is above 60%.

[0052] The reaction tank in S3 is made of stainless steel, and a stirring mechanism is preset on the stainless steel reaction tank.

[0053] The FeSO4 in S4 is a by-product of titanium dioxide production, with a content above 98%.

[0054] The stirring time of FeSO4 and the concentrated semi-finished sodium sulfide in S5 is 20 minutes.

[0055] The tablet-making and packaging unit in S6 is an integrated fully automated structure. Specific Example 1:

[0057] In this embodiment:

[0058] First, pump the sodium sulfide solution with a content of 28% - 30% into an evaporator for evaporation and concentration;

[0059] Secondly, when the content of the sodium sulfide solution is concentrated to above 60%, analyze its Fe content, measure the specific gravity, and calculate the total mass;

[0060] Next, pump the above-mentioned concentrated semi-finished sodium sulfide into a reaction tank and start the stirring mechanism on the reaction tank to stir the semi-finished sodium sulfide;

[0061] Immediately, according to the specified requirements, calculate the addition amount of FeSO4 from the data in S2, where the FeSO4 used has a content of more than 98%;

[0062] Then, during the stirring process of the sodium sulfide semi-finished product, continuously add the above-mentioned FeSO4 into the tank. After the addition is completed, continue stirring for 20 minutes until it completely reacts and is evenly mixed;

[0063] Finally, send the above-mentioned evenly mixed sodium sulfide solution to the tablet-making and packaging unit for treatment to obtain an industrial sodium sulfide product with high iron and high redness.

[0064] The above-disclosed is only a preferred embodiment of the present invention. Of course, the scope of rights of the present invention cannot be limited thereby. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.

Claims

1. A method for changing the color of industrial sodium sulfide using ferrous sulfate, characterized in that, It includes the following steps: S1: Pump the sodium sulfide solution into an evaporator for evaporation and concentration; S2: Concentrate the sodium sulfide until it meets the content requirements of the customized product, analyze its Fe content, measure the specific gravity, and calculate the total mass; S3: Pump the semi-finished sodium sulfide concentrated in S2 into a reaction tank and start stirring; S4: Calculate the addition amount of FeSO4 based on the data in S2 according to the specified requirements; S5: During the stirring process in S3, continuously add FeSO4 into the tank. After the addition is completed, continue stirring until it reacts completely and is mixed evenly; S6: Send the evenly mixed sodium sulfide solution in S5 to a tablet-making and packaging unit for treatment to obtain an industrial sodium sulfide product with high iron and high redness.

2. The method for changing the color of industrial sodium sulfide by using ferrous sulfate as described in claim 1, wherein The content of the sodium sulfide solution in S1 is 28% - 30%.

3. The method for changing the color of industrial sodium sulfide by using ferrous sulfate as described in claim 1, characterized in that, The content of the concentrated sodium sulfide in S2 is more than 60%.

4. The method for changing the color of industrial sodium sulfide by using ferrous sulfate according to claim 1, characterized in that, The reaction tank in S3 is made of stainless steel, and a stirring mechanism is preset on the stainless steel reaction tank.

5. The method for changing the color of industrial sodium sulfide by using ferrous sulfate as described in claim 1, characterized in that, The FeSO4 in S4 is a by-product of titanium dioxide production, with a content of more than 98%.

6. The method for changing the color of industrial sodium sulfide by using ferrous sulfate as described in claim 1, characterized in that, The stirring time of FeSO4 and the semi-finished sodium sulfide concentrated in S5 in S5 is 20 minutes.

7. The method for changing the color of industrial sodium sulfide by using ferrous sulfate as described in claim 1, characterized in that, The tablet-making and packaging unit in S6 is an integrated fully automated structure.

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