阅读说明：本技术 一种用熔盐氯化渣制取离子膜烧碱原料盐水的方法 (Method for preparing ionic membrane caustic soda raw material brine by using fused salt chlorination residues ) 是由 刘昌林 张衡 张小龙 张溅波 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种用熔盐氯化渣制取离子膜烧碱原料盐水的方法,属于四氯化钛生产领域废盐处理及资源回收再利用技术领域。该方法包括如下步骤：a、溶浸熔盐氯化渣到粗盐水；b、加入混碱和氧化剂,反应完全后沉淀、过滤,得到混合盐水；c、加热至90～95℃,及时加入碳酸钠溶液,反应完全后静置、过滤,得到NaCl盐水；d、向NaCl盐水中加入已消化的石灰乳或Ca(OH)-(2),反应后静置沉淀、过滤；向滤液中加入原盐,或采用浓缩方法将盐水中NaCl含量提高到305～315g/l,沉淀澄清,上清液即为离子膜烧碱生产的原料盐水。本发明方法为熔盐氯化渣的处理提供了一条有效途径,也为离子膜烧碱原料盐水提供一种新的合格来源。(The invention discloses a method for preparing ionic membrane caustic soda raw material brine by using molten salt chlorination residues, and belongs to the technical field of waste salt treatment and resource recycling in the titanium tetrachloride production field. The method comprises the following steps: a. leaching the fused salt chloride slag to obtain crude salt water; b. adding mixed alkali and an oxidant, precipitating and filtering after complete reaction to obtain mixed brine; c. heating to 90-95 ℃, adding a sodium carbonate solution in time, standing after complete reaction, and filtering to obtain NaCl brine; d. adding slaked lime milk or Ca (OH) to NaCl brine 2 Standing for precipitation and filtering after reaction; adding raw salt into the filtrate, or increasing the NaCl content in the brine to 305-315 g/l by adopting a concentration method, settling and clarifying, wherein the supernatant is the raw brine produced by the ion membrane caustic soda. The method provides an effective way for treating the molten salt chlorination slag, and also provides a new qualified source for the ionic membrane caustic soda raw material brine.)

1. A method for preparing ionic membrane caustic soda raw material brine by using fused salt chlorination residues is characterized by comprising the following steps:

a. leaching: leaching the fused salt chlorination residues with water, and filtering after complete leaching to obtain crude salt water;

b. preparing mixed brine: adding mixed alkali and oxidant into the crude brine under stirring, wherein the mixed alkali is Na₂CO₃And NaOH, wherein the oxidant is NaClO solution, and after complete reaction, the mixed salt water is obtained through precipitation and filtration;

c. preparing NaCl brine: heating the mixed brine to 90-95 ℃, adding a sodium carbonate solution in time, stirring at a constant temperature, standing after complete reaction, and filtering to obtain NaCl brine;

d. preparing raw material brine of ionic membrane caustic soda: adding slaked lime milk or Ca (OH) to NaCl brine₂Standing for precipitation and filtering after reaction; adding raw salt into the filtrate, increasing the NaCl content in the brine to 305-315 g/l, settling and clarifying, wherein the supernatant is the raw brine produced by the ionic membrane caustic soda; or increasing the NaCl concentration of the filtrate to 305-315 g/l by adopting a concentration method.

2. The method for preparing the raw brine of the ionic membrane caustic soda by using the molten salt chlorination slag as claimed in claim 1, is characterized in that: in step b, the content of active chlorine in the oxidizing agent>6 g/l; the mixed alkali is a solution with the mass concentration of 30 percent, and Na is contained in the mixed alkali₂CO₃The mass ratio of the NaOH solution to the NaOH solution is 1: 1-5.

3. The method for preparing the raw brine of the ionic membrane caustic soda by using the molten salt chlorination slag as claimed in claim 2, is characterized in that: the volume ratio of the crude brine to the mixed alkali to the oxidant is 1: 0.2-1.2: 0.1-0.2.

4. The method for preparing the raw brine of the ionic membrane caustic soda by using the molten salt chlorination slag as claimed in claim 3, is characterized in that: in the step b, the reaction time is more than or equal to 10 hours.

5. The method for preparing the raw brine of the ionic membrane caustic soda by using the molten salt chlorination slag as claimed in claim 1, is characterized in that: the sodium carbonate solution is saturated solution, and the adding amount of the sodium carbonate solution and Mg in the mixed brine are according to the ratio of sodium carbonate in the solution to Mg in the mixed brine²⁺The molar ratio of the raw materials is 1.0-1.2: 1.0.

6. The method for preparing the raw brine of the ionic membrane caustic soda by using the molten salt chlorination slag as claimed in claim 1, is characterized in that: in the step a, the mass ratio of the molten salt chlorination residues to the water is 1: 1-5.

7. The method for preparing the raw brine of the ionic membrane caustic soda by using the molten salt chlorination slag as claimed in claim 1, is characterized in that: in the step d, the mass concentration of the lime milk is 10-21%.

8. The method for preparing the raw brine of the ionic membrane caustic soda by using the molten salt chlorination slag as claimed in claim 1, is characterized in that: in step d, lime milk or Ca (OH)₂The dosage of the water is according to the CO in the brine₃ ^2-The content is determined, and the molar ratio of the added calcium to the carbonate in the salt water is 0.95-1.0: 1.0.

9. The method for preparing the raw brine of the ionic membrane caustic soda by using the molten salt chlorination slag as claimed in claim 8, is characterized in that: in the step d, the precipitation time is more than or equal to 2 hours.

10. The method for preparing the raw brine of the ionic membrane caustic soda by using the molten salt chlorination slag as claimed in claim 1, is characterized in that: the raw salt used in the step d is that the NaCl content is more than or equal to 95 percent, the total content of Ca and Mg is less than or equal to 1.0 percent,SO₄ ^2-Less than or equal to 0.5 percent and the dissolution temperature is 55 +/-2 ℃.

Technical Field

The invention belongs to the technical field of waste salt treatment and resource recycling in the titanium tetrachloride production field, and particularly relates to a method for preparing ionic membrane caustic soda raw material brine by using molten salt chlorination residues.

Background

About 80 percent of global titanium resources are primary titanium ores, 95 percent of the national titanium resources are primary titanium ores, and the primary titanium ores (such as Panxi vanadium titano-magnetite) are used asTitanium slag smelted from initial resources is generally high in calcium and magnesium (MgO + CaO is more than or equal to 7 percent) and TiO₂Low grade (74-76 percent), can not be used as raw materials for boiling chlorination production, and only can adopt a molten salt chlorination method to produce TiCl₄Further producing sponge titanium and titanium white chloride. Years of production practice of climbing steel group shows that TiCl produced by molten salt chlorination₄The cost of the method is 30 percent lower than that of boiling chlorination. But the production amount of the waste salt and the molten salt chlorination slag of the molten salt chlorination is large, the components are complex, and the treatment and the utilization are difficult. At present, the treatment is generally carried out at home and abroad by adopting a filling cooling-crushing-lime mixing special slag yard landfill mode, and more than 80 percent of components of the treatment are soluble metal chlorides, so that the risk of pollution to soil and underground water is great. Once the country prohibits landfills, the enterprise is at risk of a shutdown. Therefore, the recycling treatment of the fused salt chlorination residues becomes a 'bottleneck' technical problem for the survival and development of the fused salt chlorination process, and needs to be solved urgently.

Disclosure of Invention

The invention aims to solve the technical problem that the existing molten salt chlorination slag treatment mode pollutes the environment, provides a method for directly preparing brine meeting the ionic membrane caustic soda primary brine standard by using molten salt chlorination slag, and relieves the problem of molten salt chlorination slag treatment.

The technical scheme adopted by the invention for solving the technical problems is as follows: a method for preparing ionic membrane caustic soda raw material brine by using fused salt chlorination residues comprises the following steps:

a. leaching: leaching the fused salt chlorination residues with water, and filtering after complete leaching to obtain crude salt water;

b. preparing mixed brine: adding mixed alkali and oxidant into the crude brine under stirring, wherein the mixed alkali is Na₂CO₃And NaOH, wherein the oxidant is NaClO solution, and after complete reaction, the mixed salt water is obtained through precipitation and filtration;

c. preparing NaCl brine: heating the mixed brine to 90-95 ℃, adding a sodium carbonate solution in time, stirring at a constant temperature, standing after complete reaction, and filtering to obtain NaCl brine;

d. preparing raw material brine of ionic membrane caustic soda: adding slaked lime milk or Ca (OH) to NaCl brine₂Standing for precipitation and filtering after reaction; filter with filter elementAdding raw salt into the solution, increasing the NaCl content in the brine to 305-315 g/l, settling and clarifying, wherein the supernatant is the raw brine produced by the ionic membrane caustic soda; or increasing the NaCl concentration of the filtrate to 305-315 g/l by adopting a concentration method.

Wherein, in the step b of the method, the content of active chlorine in the oxidant>6 g/l; the mixed alkali is a solution with the mass concentration of 30 percent, and Na is contained in the mixed alkali₂CO₃The mass ratio of the NaOH solution to the NaOH solution is 1: 1-5.

Furthermore, the volume ratio of the crude brine to the mixed alkali to the oxidant is 1: 0.2-1.2: 0.1-0.2.

And further, in the step b, the reaction time is more than or equal to 10 hours.

Wherein, in the method, the sodium carbonate solution is saturated solution, and the adding amount is according to the ratio of sodium carbonate in the solution to Mg in the mixed brine²⁺The molar ratio of the raw materials is 1.0-1.2: 1.0.

In the step a of the method, the mass ratio of the molten salt chlorination residues to the water is 1: 1-5.

In the step d of the method, the mass concentration of the lime milk is 10-21%.

Wherein in the step d of the method, lime milk or Ca (OH)₂The dosage of the water is according to the CO in the brine₃ ^2-The content is determined, and the molar ratio of the added calcium to the carbonate in the salt water is 0.95-1.0: 1.0.

Wherein, in the step d of the method, the precipitation time is more than or equal to 2 hours.

Wherein in the step d of the method, the used raw salt comprises more than or equal to 95 percent of NaCl, less than or equal to 1.0 percent of Ca and Mg, and SO₄ ^2-Not more than 0.5 percent, and the dissolution temperature is 55 +/-2 ℃, which are mass contents.

The invention has the beneficial effects that: the method comprises the steps of firstly, leaching the fused salt chloride slag, adding mixed alkali and an oxidant, and deeply removing ammonium, F, Fe, Mn and other ions in crude brine, wherein the ammonium is<0.1mg/l、F<0.1mg/l、Fe<1mg/l、Mn<1 mg/l; adding saturated sodium carbonate solution to make Mg²⁺Less than 60 mg/l; adding lime milk or slaked lime to make CO in salt water₃ ^2-Less than or equal to 0.5 g/l. The purified brine is supplemented with original salt or concentrated to prepare composite saltThe starting material for the biofilm caustic soda requirement is virgin (saturated brine).

Detailed Description

The process of the invention can be carried out in particular in the following manner.

A method for preparing ionic membrane caustic soda raw material brine by using fused salt chlorination residues comprises the following steps:

a. leaching: dissolving and leaching the fused salt chlorination residues with water according to the mass ratio of 1: 1-5, and filtering after complete dissolution and leaching to obtain crude salt water;

b. preparing mixed brine: adding a mixed alkali solution with the mass concentration of 30 percent and an oxidant into the crude brine under stirring, wherein the mixed alkali solution is Na₂CO₃And NaOH solution, Na₂CO₃The mass ratio of the active chlorine to NaOH is 1: 1-5, and the oxidant is active chlorine content>6g/l of NaClO solution, the volume ratio of the crude salt water to the mixed alkali solution to the oxidant is 1: 0.2-1.2: 0.1-0.2, and after the reaction is over 10 hours, the mixed salt water is precipitated and filtered to obtain the mixed salt water;

c. preparing NaCl brine: heating the mixed salt water to 90-95 ℃, adding saturated sodium carbonate solution in time, wherein the adding amount is according to the ratio of sodium carbonate in the solution to Mg in the mixed salt water²⁺Adding the materials according to the molar ratio of 1.0-1.2: 1.0, stirring at constant temperature, standing after complete reaction, and filtering to obtain NaCl brine;

d. preparing raw material brine of ionic membrane caustic soda: adding slaked lime milk or Ca (OH) to NaCl brine₂The dosage is according to CO in the brine₃ ^2-The content is determined, and the molar ratio of the added calcium to the carbonate in the salt water is 0.95-1.0: 1.0; standing for more than 2h, and filtering; adding raw salt into the filtrate (brine), increasing the NaCl content in the brine to 305-315 g/l, settling and clarifying, wherein the supernatant is the raw brine produced by the ion membrane caustic soda; concentration may also be used to increase the NaCl concentration of the brine to 315 g/l.

The present invention will be further described with reference to the following examples, but the scope of the present invention is not limited thereto.

Example one

Taking 1 kg of fused salt chlorination slag, crushing (the diameter of the slag is less than or equal to 2.5cm), adding2.5L of tap water was added, stirred and dissolved. After the molten salt chlorination residues are completely dissolved, filtering to obtain 2.22L crude salt water, wherein the specific components are shown in Table 1. Slowly adding 1.198L of 30% mixed alkali solution containing Na₂CO₃The solution was mixed with NaOH at a mass ratio of 1: 2, and 200mL of NaClO solution having an active chlorine content of 16g/L was added thereto to effect a complete reaction for 48 hours, followed by precipitation and filtration to obtain 2.94L of mixed brine (water quality shown in Table 2). Adding Mg into mixed brine²⁺Reacting saturated sodium carbonate solution with a molar ratio of 1.1 at 95 ℃ for 40min, settling, clarifying, and filtering supernatant to obtain 2.82L filtrate, namely magnesium-removed NaCl brine (see Table 3). 73g of digested lime milk with a concentration of 20% was added to the magnesium-removed brine, stirred well, reacted for 4h, and 2.79L of the filtrate was filtered, the filtrate composition being shown in Table 4. And (3) keeping the temperature of the filtrate at 55 ℃, adding 314.4g of industrial salt with the purity of 98.5% into the filtrate under the stirring condition, fully stirring the mixture to completely dissolve the salt, standing the mixture for 4 hours to obtain a supernatant, namely NaCl315g/l saturated saline meeting the requirements of the ionic membrane caustic soda production process, wherein the analysis results are shown in Table 5.

Table 1 example a crude brine analysis result

Table 2 example-mixed brine analysis results

Table 3 example a result of analysis of a magnesium-depleted NaCl brine

Table 4 example a further purified NaCl brine analysis results

Table 5 analysis results of saturated brine prepared in example one

Example two

1 kg of waste molten chloride salt was similarly quenched with 2.2L of tap water, and filtered to obtain 2.02L of crude brine (see Table 6). Slowly adding 1.30L of 30% mixed alkali solution containing Na₂CO₃The mass ratio of the solution to NaOH was 1: 2, 270mL of NaClO solution having an active chlorine content of 12g/L was added thereto, the mixture was allowed to react for 24 hours, and the precipitate was filtered to obtain 3.12L of mixed brine (water quality shown in Table 7). Adding Mg into mixed brine²⁺Reacting saturated sodium carbonate solution with a molar ratio of 1.09 at 92 ℃ for 40min, clarifying the precipitate, and filtering the supernatant to obtain filtrate, namely the magnesium-removed NaCl brine (see Table 8). 103g of digested lime cream with a concentration of 16% was added to the magnesium-removed brine, stirred well, reacted for 4 hours, and 2.68L of filtrate was filtered, the filtrate composition being shown in Table 9. The filtrate was evaporated until a small amount of crystals appeared and cooled to room temperature, and the supernatant was saturated NaCl brine (see table 10 for analytical results).

TABLE 6 example II crude brine analysis results

Table 7 example two mixed brine analysis results

TABLE 8 example two magnesium removal NaCl brine analysis results

Table 9 analysis of NaCl brine from example two further purification

Table 10 analysis results of saturated brine prepared in example two

Comparative example 1

Crude brine is prepared by the same method as the example one, mixed alkali is not added when the crude brine is prepared into mixed brine, only NaOH is added, the adding ratio of alkali liquor to crude brine is (V/V is 0.65:1), and Ca in the prepared mixed brine is added²⁺、Mg²⁺Almost all enter the solution, the slag phase is difficult to filter due to low content of Mg and Ca salts, and the composition is shown in Table 11.

Table 11 comparative example-mixed brine analysis results

Comparative example No. two

Crude brine and mixed brine were prepared in the same manner as in example one, except that if the active chlorine in the oxidizing agent was too low, e.g., 2g/l, NH was added to the prepared mixed brine₄ ⁺、F^-And the contents of TFe and Mn are too high, and TFe and NH in the prepared brine are obtained after the mixed brine is continuously subjected to magnesium and carbonate removal₄ ⁺、F^-The content of the active carbon is less than 1 mg/l. The brine composition is shown in table 12.

Table 12 analysis results of mixed brine of comparative example

Comparative example three:

crude brine and mixed brine were prepared in the same manner as in example one, except that the mixed brine had a magnesium removal temperature of 70 ℃ and Mg was contained in the magnesium removal brine²⁺682Mg/l higher than Mg in ion membrane caustic soda saturated brine²⁺Less than or equal to 500 mg/l.

TABLE 13 analysis results of the triple magnesium-removed brine of comparative example