阅读说明：本技术 轻烧粉浸钙废水循环利用方法和应用 (Recycling method and application of calcium leaching wastewater of light calcined powder ) 是由 阮书锋 董波 王振文 江培海 董行 张永禄 揭晓武 王殿忠 尹飞 郜伟 崔成旺 于 2021-02-07 设计创作，主要内容包括：本发明提供了一种轻烧粉浸钙废水循环利用方法和应用,涉及氧化镁制备技术领域。本轻烧粉浸钙废水循环利用方法,先将轻烧粉浸钙废水和含钙轻烧粉形成的混合液与含CO-2废气在喷射器内混合脱钙,然后将得到的脱钙浆料进行固液分离,得到脱钙后液,脱钙后液再经任选的浓缩处理后,作为含钙轻烧粉的浸出剂和/或含钙轻烧粉浸钙处理后固液分离的洗水回用；其中,利用含CO-2废气和含钙轻烧粉分别作为轻烧粉浸钙废水脱钙过程中的沉淀剂和中和剂,实现轻烧粉浸钙废水的脱钙,且采用喷射器实现混合液与含CO-2废气的充分混合,可提高脱钙效率；通过对脱钙后液的处理,实现轻烧粉浸钙废水的循环利用,废水零排放,使得碳排放和除钙成本得到有效降低。(The invention provides a recycling method and application of calcium leaching wastewater of caustic soda powder, and relates to the technical field of magnesium oxide preparation. The method for recycling the calcium-leaching wastewater of the light calcined powder comprises the steps of firstly mixing the mixed solution of the calcium-leaching wastewater of the light calcined powder and the calcium-containing light calcined powder with CO 2 Mixing the waste gas in an ejector for decalcification, then carrying out solid-liquid separation on the obtained decalcification slurry to obtain a decalcification solution, and recycling the decalcification solution as a leaching agent of the calcium-containing light-burned powder and/or washing water of the solid-liquid separation after the calcium-containing light-burned powder is subjected to calcium leaching treatment after optional concentration treatment; wherein the CO is utilized 2 The waste gas and the calcium-containing light calcined powder are respectively used as a precipitator and a neutralizer in the decalcification process of the calcium leaching wastewater of the light calcined powder to realize the decalcification of the calcium leaching wastewater of the light calcined powderCalcium, and the ejector is adopted to realize the mixed liquid and the CO 2 The waste gas is fully mixed, so that the decalcification efficiency can be improved; through the treatment of the decalcified liquid, the recycling of the calcium leaching wastewater of the light calcined powder is realized, the zero discharge of the wastewater is realized, and the carbon discharge and the decalcification cost are effectively reduced.)

1. The recycling method of the waste water from calcium leaching of the light calcined powder is characterized by comprising the following steps:

(a) providing calcium-leaching wastewater of the calcium-containing light calcined powder, which is formed by calcium leaching treatment of a leaching agent;

(b) mixing the mixed solution of the calcium-leaching wastewater of the light calcined powder and the calcium-containing light calcined powder with CO₂Mixing the waste gas in an ejector, and decalcifying to obtain decalcified slurry;

carrying out solid-liquid separation on the decalcified slurry to obtain a decalcified liquid;

(c) and (3) optionally concentrating the decalcified liquid, and recycling the decalcified liquid as a leaching agent of the calcium-containing light-burned powder and/or washing water for solid-liquid separation after the calcium-containing light-burned powder is subjected to calcium leaching treatment.

2. The recycling method of the calcium leaching wastewater of the light calcined powder as claimed in claim 1, wherein in the step (a), the calcium-containing light calcined powder is prepared by calcining magnesite, and the magnesite comprises magnesite and/or dolomite ore.

3. The recycling method of the waste water from the leaching of calcium from calomel of claim 2, wherein in the step (a), the leaching agent comprises a magnesium chloride leaching agent and/or a brine leaching agent;

and/or in the step (a), the calcium content in the calcium leaching wastewater of the light calcined powder is 2-16g/L, the magnesium content is 0.3-5.0g/L, and the chlorine content is 5-45 g/L.

4. The recycling method of the calcium-leaching wastewater of the light calcined powder as claimed in claim 1, wherein in the step (b), the mass of calcium in the calcium-containing light calcined powder is 0.5-3 times of the mass of calcium in the calcium-leaching wastewater of the light calcined powder.

5. The recycling method of the waste water from the calcium leaching of the light calcined powder as claimed in claim 2, wherein in the step (b), the waste water contains CO₂The waste gas comprises hydrogen formed by the waste gas generated in the process of calcining the magnesium ore and/or calcium-containing light calcined powder through the calcium leaching treatment of a leaching agentThe magnesium oxide generates waste gas during the calcination process.

6. The recycling method of the waste water from the calcium leaching of the light calcined powder as claimed in claim 5, wherein in the step (b), the waste water contains CO₂CO in exhaust gas₂The volume fraction of (A) is 1-30%;

and/or, in step (b), contains CO₂The flow rate of the exhaust gas is calculated according to equation (1):

Q =(m_Ca×0.56×n)/(V×t)（1）

wherein Q is CO₂The flow rate of the waste gas is in unit of cubic meter per hour; m is_CaThe unit is kilogram of the mass of calcium in the mixed solution; n is multiple and is 8-100; v is a group containing CO₂CO in exhaust gas₂Volume fraction of (a); t is time in hours.

7. The recycling method of the waste water from the calcium leaching of the light calcined powder as claimed in claim 1, wherein in the step (b), the decalcification time is 2-15h, and the decalcification temperature is 20-50 ℃;

and/or the pH value of decalcification is 7.0-8.5.

8. The method for recycling the wastewater from the calcium leaching of the calcined calomel as claimed in any one of claims 1 to 7, wherein in the step (c), when the chlorine content in the decalcified solution is less than 20 g/L, the decalcified solution is concentrated to obtain salt-containing concentrated water and salt-containing fresh water; the salt-containing concentrated water is recycled as a leaching agent of the calcium-containing light calcined powder, and the salt-containing fresh water is recycled as washing water for solid-liquid separation after the calcium-containing light calcined powder is subjected to calcium leaching treatment;

or when the chlorine content in the decalcified liquid is 20-45g/L, the decalcified liquid is used as a leaching agent of the calcium-containing light calcined powder for recycling.

9. The recycling method of the waste water from the calcium leaching of the light calcined powder as claimed in claim 8, wherein in the step (c), a reverse osmosis membrane is used for concentration treatment.

10. The use of the method for recycling the waste water from the leaching of calcium with calomel as claimed in any one of claims 1 to 9 in the field of the preparation of magnesium oxide.

Technical Field

The invention relates to the technical field of magnesium oxide preparation, in particular to a recycling method and application of calcium leaching wastewater of light calcined powder.

Background

With the increasing exhaustion of high-grade magnesite at present, the preparation of high-quality magnesium oxide from magnesite with high calcium content is of great concern. Because the calcium content in the light calcined powder obtained by directly calcining magnesite with high calcium content is up to 2-10%, and the product cannot meet the quality requirement of high-purity magnesium oxide, most of the light calcined powder with high calcium content is leached by brine or magnesium chloride solution to remove calcium, and the calcium in the light calcined powder is leached into the solution, so that the removal of the calcium in the magnesium oxide is realized. But the high-purity magnesium oxide is generated by about 5-10 m every 1t in the leaching process³The calcium content in the waste water is higher, about2.5-15g/L, and can not be discharged and recycled without being subjected to calcium removal treatment. At present, the technology for effectively treating and recycling the calcium-leaching wastewater of the light calcined powder is urgently needed to be developed.

Accordingly, the present invention is directed to solving at least one of the problems set forth above.

Disclosure of Invention

The invention aims to provide a recycling method of calcium carbonate leaching wastewater of caustic calcined lime to solve the technical problems that the existing calcium carbonate leaching wastewater of caustic calcined lime cannot be directly discharged and cannot be recycled.

The second purpose of the invention is to provide the application of the recycling method of the waste water from calcium leaching of the light calcined powder.

In order to achieve the above purpose of the present invention, the following technical solutions are adopted:

the invention provides a recycling method of calcium leaching wastewater of caustic calcined powder, which comprises the following steps:

(a) providing calcium-leaching wastewater of the calcium-containing light calcined powder, which is formed by calcium leaching treatment of a leaching agent;

(b) mixing the mixed solution of the calcium-leaching wastewater of the light calcined powder and the calcium-containing light calcined powder with CO₂Mixing the waste gas in an ejector, and decalcifying to obtain decalcified slurry;

carrying out solid-liquid separation on the decalcified slurry to obtain a decalcified liquid; wherein the decalcified liquid comprises a low-salt decalcified liquid and a high-salt decalcified liquid;

(c) and (3) optionally concentrating the decalcified liquid, and recycling the decalcified liquid as a leaching agent of the calcium-containing light-burned powder and/or washing water for solid-liquid separation after the calcium-containing light-burned powder is subjected to calcium leaching treatment.

Further, on the basis of the technical scheme of the invention, in the step (a), the calcium-containing light-burned powder is prepared by calcining magnesium ore, wherein the magnesium ore comprises magnesite and/or dolomite ore.

Further, on the basis of the above technical scheme of the present invention, in the step (a), the leaching agent comprises a magnesium chloride leaching agent and/or a brine leaching agent;

and/or in the step (a), the calcium content in the calcium leaching wastewater of the light calcined powder is 2-16g/L, the magnesium content is 0.3-5.0g/L, and the chlorine content is 5-45 g/L.

Further, on the basis of the technical scheme of the invention, in the step (b), the mass of calcium in the calcium-containing light calcined powder is 0.5-3 times of that in the calcium-soaking wastewater of the light calcined powder.

Further, on the basis of the above technical solution of the present invention, in the step (b), the carbon dioxide (CO) is contained₂The waste gas comprises waste gas generated in the calcining process of the magnesium ore and/or waste gas generated in the calcining process of magnesium hydroxide formed by treating calcium-containing light calcined powder with a leaching agent.

Further, on the basis of the above technical solution of the present invention, in the step (b), the carbon dioxide (CO) is contained₂CO in exhaust gas₂The volume fraction of (A) is 1-30%;

and/or, in step (b), contains CO₂The flow rate of the exhaust gas is calculated according to equation (1):

Q =(m_Ca×0.56×n)/(V×t) （1）

wherein Q is CO₂The flow rate of the waste gas is in unit of cubic meter per hour; m is_CaThe unit is kilogram of the mass of calcium in the mixed solution; n is multiple and is 8-100; v is a group containing CO₂CO in exhaust gas₂Volume fraction of (a); t is time in hours.

Further, on the basis of the technical scheme of the invention, in the step (b), the decalcification time is 2-15h, and the decalcification temperature is 20-50 ℃;

and/or the pH value of decalcification is 7.0-8.5.

Further, on the basis of the technical scheme of the invention, in the step (b), when the chlorine content in the decalcified liquid is less than 20 g/L in the step (c), concentrating the decalcified liquid to obtain salt-containing concentrated water and salt-containing fresh water; the salt-containing concentrated water is recycled as a leaching agent of the calcium-containing light calcined powder, and the salt-containing fresh water is recycled as washing water for solid-liquid separation after the calcium-containing light calcined powder is subjected to calcium leaching treatment;

or when the chlorine content in the decalcified liquid is 20-45g/L, the decalcified liquid is used as a leaching agent of the calcium-containing light calcined powder for recycling.

Further, on the basis of the above technical scheme of the present invention, in the step (c), a reverse osmosis membrane is used for concentration treatment.

The invention also provides application of the recycling method of the calcium leaching wastewater of the light calcined powder in the field of magnesium oxide preparation.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention provides a recycling method of calcium-leaching wastewater of light calcined powder, which comprises the steps of firstly, mixing a mixed solution formed by the calcium-leaching wastewater of light calcined powder and calcium-containing light calcined powder with CO₂Mixing the waste gas in an ejector for decalcification, then carrying out solid-liquid separation on the obtained decalcification slurry to obtain a decalcification solution, and recycling the decalcification solution as a leaching agent of the calcium-containing light-burned powder and/or washing water for solid-liquid separation after the calcium-containing light-burned powder is subjected to calcium leaching treatment after optional concentration treatment; wherein by using a CO-containing gas₂The waste gas and the calcium-containing light calcined powder are respectively used as a precipitator and a neutralizer in the decalcification process of the calcium-leaching wastewater of the light calcined powder to realize the decalcification of the calcium-leaching wastewater of the light calcined powder, and an ejector is adopted to realize the mixed solution and the CO-containing mixed solution₂The waste gas is fully mixed, so that the decalcification efficiency can be improved; meanwhile, the recycling of the calcium leaching wastewater of the light calcined powder is realized through the treatment of the decalcified liquid, the zero discharge of the wastewater is realized, and the carbon discharge and the calcium removal cost are both effectively reduced;

in addition, the recycling method of the calcium leaching wastewater of the light calcined powder has simple operation and stable process, and is suitable for industrial large-scale production.

(2) The invention provides the application of the recycling method of the light calcined powder calcium leaching wastewater, and the recycling method has good application in the field of magnesium oxide preparation in view of the advantages of the recycling method of the light calcined powder calcium leaching wastewater.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a process flow diagram of the method for recycling calcium carbonate leaching wastewater of light calcined powder according to an embodiment of the present invention;

fig. 2 is a structural view of a decalcifying apparatus according to an embodiment of the present invention.

Icon: 1-decalcification stirring tank; 2-a circulating pump; 3-an ejector; 4-an air inlet duct; 11-a feed port; 12-a first inlet well; 13-a second liquid inlet hole; 14-a vent hole; 15-discharge hole; 21-a first valve; 41-second valve.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

According to a first aspect of the invention, a method for recycling waste water generated in calcium leaching of light calcined powder is provided, and a process flow diagram is shown in fig. 1, and the method comprises the following steps:

(a) providing calcium-leaching wastewater of the calcium-containing light calcined powder, which is formed by calcium leaching treatment of a leaching agent;

(b) mixing the mixed solution of the calcium-leaching wastewater of the light calcined powder and the calcium-containing light calcined powder with CO₂Mixing the waste gas in an ejector, and decalcifying to obtain decalcified slurry;

carrying out solid-liquid separation on the decalcified slurry to obtain a decalcified liquid; wherein the decalcified liquid comprises a low-salt decalcified liquid and a high-salt decalcified liquid;

(c) and (3) optionally concentrating the decalcified liquid, and recycling the decalcified liquid as a leaching agent of the calcium-containing light-burned powder and/or washing water for solid-liquid separation after the calcium-containing light-burned powder is subjected to calcium leaching treatment.

Specifically, in the step (a), a leaching agent is adopted to carry out calcium leaching reaction on the calcium-containing light calcined powder to generate a magnesium-containing precipitate (magnesium hydroxide) and a calcium salt. Taking the leaching agent as an example, the magnesium chloride leaching agent is adopted as the leaching agent, and the chemical reaction involved in the calcium leaching reaction is as follows:

Ca(OH)₂ + MgCl₂ = Mg(OH)₂↓ + CaCl₂

therefore, the waste water from the calcium leaching of the light calcined powder mainly contains calcium ions, magnesium ions and chloride ions with certain concentrations.

In step (b), the catalyst is prepared by using a catalyst containing CO₂And the waste gas is used as a precipitator to decalcify the waste water after the light calcined powder is soaked in calcium. Containing CO₂The waste gas mainly comes from CO-containing gas generated in the processes for preparing high-purity magnesium oxide (such as calcining magnesite and calcining magnesium hydroxide)₂Of the exhaust gas of (1). It is noted that the catalyst contains CO₂The exhaust gas contains CO₂And further containing other gases (N)₂、O₂And water vapor) other gases have no adverse effect on the decalcification process. By using a gas containing CO₂The waste gas can be effectively utilized as a precipitator, and the production cost can be reduced.

Calcium-containing light-burned powder (the main component comprises magnesium oxide) is used as a neutralizing agent to neutralize hydrogen ions formed in the decalcification process. The calcium-containing light calcined powder can effectively neutralize hydrogen ions formed in the decalcification process and promote the reaction while not introducing other metal elements. The chemical reactions involved in the decalcification in step (b) are as follows:

CaCl₂ + CO₂ + H₂O = CaCO₃↓ + 2HCl

MgO + 2HCl = MgCl₂ + H₂O

mixed liquor formed by calcium-soaking waste water of light calcined powder and calcium-containing light calcined powder and CO₂The waste gas is mixed in the ejector, and the ejector can realize the mixing of the mixed liquid and the CO₂The waste gas is fully mixed, and the decalcification efficiency is improved.

And after the decalcification is finished, carrying out solid-liquid separation on the decalcification slurry to obtain a decalcification solution. The solid-liquid separation method is not limited, and a separation method commonly used in the art may be employed.

In the step (c), "optional concentration treatment" means that the solution after decalcification may or may not be subjected to concentration treatment. Whether the concentration treatment is carried out or not is mainly determined according to the content or the height of chlorine in the decalcified liquid.

When the content of chlorine in the decalcified liquid is high, the decalcified liquid can be directly used as a leaching agent of the calcium-containing light calcined powder for recycling. When the content of chlorine in the decalcified liquid is low, the decalcified liquid can be concentrated to obtain salt-containing concentrated water and salt-containing fresh water. The salt-containing concentrated water has high chlorine content, so the method can return to the leaching agent of the calcium-containing light calcined powder in the preparation process of the high-purity magnesium oxide for recycling. Although the content of chlorine in the salt-containing fresh water is low, the salt-containing fresh water does not meet the direct discharge standard, and the salt-containing fresh water can be reused as washing water for solid-liquid separation after the calcium-containing light calcined powder is subjected to calcium leaching treatment. Therefore, the decalcified liquid can be recycled no matter whether the decalcified liquid is concentrated or not, and zero discharge of wastewater is realized.

The invention provides a recycling method of calcium-leaching wastewater of light calcined powder, which comprises the steps of firstly, mixing a mixed solution formed by the calcium-leaching wastewater of light calcined powder and calcium-containing light calcined powder with CO₂Mixing the waste gas in an ejector, decalcifying, then carrying out solid-liquid separation on the obtained decalcified slurry to obtain a decalcified liquid, and recycling the decalcified liquid as a leaching agent of the calcium-containing light-burned powder and/or washing water of the solid-liquid separation after the calcium-containing light-burned powder is subjected to calcium leaching treatment after optional concentration treatment; wherein by using a CO-containing gas₂The waste gas and the calcium-containing light calcined powder are respectively used as a precipitator and a neutralizer in the decalcification process of the calcium-leaching wastewater of the light calcined powder to realize the decalcification of the calcium-leaching wastewater of the light calcined powder, and an ejector is adopted to realize the mixed solution and the CO-containing mixed solution₂The waste gas is fully mixed, so that the decalcification efficiency can be improved; meanwhile, the recycling of the calcium leaching wastewater of the light calcined powder is realized through the treatment of the decalcified liquid, the zero discharge of the wastewater is realized, and the carbon discharge and the calcium removal cost are both effectively reduced.

In addition, the recycling method of the calcium leaching wastewater of the light calcined powder has simple operation and stable process, and is suitable for industrial large-scale production.

As an alternative embodiment of the present invention, in the step (a), the calcium-containing soft burning powder is prepared by calcining magnesite, and the magnesite comprises magnesite and/or dolomite ore.

By "and/or" herein is meant that the magnesite may include only magnesite, may include only dolomite ore, or may include both magnesite and dolomite ore.

As an alternative embodiment of the present invention, in step (a), the leaching agent comprises a magnesium chloride leaching agent and/or a brine leaching agent.

By "and/or" herein is meant that the leachant may comprise only a magnesium chloride leachant, may comprise only a brine leachant, or may comprise both a magnesium chloride leachant and a brine leachant.

It should be noted that, after the wastewater from the leaching of calcium from light calcined powder is treated by the recycling method of the present invention, the leaching agent may also include a substance from which the decalcified solution is recycled after being optionally concentrated.

As an optional embodiment of the invention, in the step (a), the calcium content in the calcium carbonate leaching wastewater of the light calcined powder is 2-16g/L, the magnesium content is 0.3-5.0g/L, and the chlorine content is 5-45 g/L.

Typical but non-limiting calcium content in the calcium carbonate leaching wastewater of the light calcined powder is 2.0g/L, 2.5g/L, 3.0g/L, 4.0g/L, 5.0g/L, 6.0g/L, 8.0g/L, 10.0g/L, 12.0g/L, 14.0g/L, 15.0g/L or 16.0 g/L; typical but non-limiting amounts of magnesium are 0.3g/L, 0.5g/L, 1.0g/L, 2.0g/L, 2.5g/L, 3.0g/L, 4.0g/L or 5.0 g/L. Typical but non-limiting chlorine levels are 5.0g/L, 6.0g/L, 8.0g/L, 10.0g/L, 15.0g/L, 20.0g/L, 25.0g/L, 30.0g/L, 35.0g/L, 40.0g/L, or 45.0 g/L.

By further limiting the content of calcium, the content of magnesium and the content of chlorine in the calcium-containing calcined coke wastewater, the calcium in the calcium-containing calcined coke is fully leached.

Adding calcium-containing light calcined powder and CO into the calcium-leaching wastewater of the light calcined powder₂And carrying out decalcification treatment on the waste gas. As an alternative embodiment of the present invention, in the step (b), the mass of calcium in the calcium-containing soft burning powder is 0.5 to 3 times of the mass of calcium in the waste water from the calcium leaching of the soft burning powder.

The addition amount of the calcium-containing light-burned powder is calculated by the mass of calcium. The mass of the calcium in the calcium-containing light calcined powder is typically but not limited to 0.5 time, 1.0 time, 1.5 times, 2.0 times, 2.5 times or 3.0 times of the mass of the calcium in the calcium leaching wastewater of the light calcined powder.

As an alternative embodiment of the present invention, in step (b), the composition contains CO₂The waste gas comprises waste gas generated in the calcining process of the magnesium ore and/or waste gas generated in the calcining process of magnesium hydroxide formed by treating calcium-containing light calcined powder with a leaching agent.

As an alternative embodiment of the present invention, in step (b), the composition contains CO₂CO in exhaust gas₂The volume fraction of (A) is 1-30%.

Containing CO₂CO in exhaust gas₂Is typically, but not limited to, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, or 30%.

As an alternative embodiment of the present invention, in step (b), the composition contains CO₂The flow rate of the exhaust gas is calculated according to equation (1):

Q =(m_Ca×0.56×n)/(V×t) （1）

wherein Q is CO₂Flow rate of exhaust gas in cubic meter per hour (m)³/h）；m_CaThe unit is the weight of the calcium in the mixed solution and is kilogram (kg); n is multiple and is 8-100; v is a group containing CO₂CO in exhaust gas₂Volume fraction of (c); t is time in hours (h).

As an alternative embodiment of the invention, in step (b), the decalcification time is 2-15h and the decalcification temperature is 20-50 ℃.

Typical but not limiting times for decalcification are 2h, 3h, 4h, 5h, 6h, 8h, 10h, 12h, 13h, 14h or 15 h. Typical but non-limiting temperatures for decalcification are 20 deg.C, 25 deg.C, 30 deg.C, 35 deg.C, 40 deg.C, 45 deg.C or 50 deg.C.

As an alternative embodiment of the invention, the pH value for decalcification is 7.0 to 8.5. Typical but non-limiting pH values for decalcification are 7.0, 7.5, 8.0 or 8.5.

The pH value of decalcification affects the decalcification rate, and thus it is necessary to control the pH value within a specific range. If the pH is too high (higher than 8.5), the consumption of the neutralizing agent (calcium-containing calcined coke) is high, and the removal of calcium is incomplete, and if the pH is too low (lower than 7.0), the back dissolution of calcium is likely to occur.

The calcium in the mixed liquor is stably and effectively removed by further limiting the decalcification time, temperature and pH value.

The apparatus for conducting decalcification is not particularly limited. As an alternative embodiment of the invention, the decalcifying device comprises a decalcifying stirring tank 1, a circulating pump 2 and an ejector 3, and the specific structure is shown in figure 2;

be equipped with feed port 11 on the tank top of decalcification agitator tank 1, first feed inlet hole 12, second feed inlet hole 13 and exhaust hole 14, the tank bottom is equipped with relief hole 15, feed inlet hole 11 is arranged in adding calcium-containing light burning powder to decalcification agitator tank 1, first feed inlet hole 12 is arranged in adding the waste water that soaks calcium to the light burning powder in the decalcification agitator tank 1, second feed inlet hole 13 is used for realizing the intercommunication of sprayer 3 and decalcification agitator tank 1, exhaust hole 14 is used for discharging the waste gas after the decalcification agitator tank 1 decalcification, relief hole 15 is used for realizing the intercommunication of circulating pump 2 and decalcification agitator tank 1, still be equipped with the baffling board in the decalcification agitator tank 1.

Circulating pump 2 sets up in the outside of decalcification agitator tank 1, and discharge hole 15 and the 1 intercommunication of decalcification agitator tank are passed through to circulating pump 2's one end, and the other end passes through pipeline and sprayer 3 intercommunication. A first valve 21 for adjusting the flow rate of the liquid is provided in a pipe connecting the circulation pump 2 and the ejector 3.

The ejector 3 is arranged at the top of the decalcification stirring tank 1 and is communicated with the decalcification stirring tank 1 through a second liquid inlet hole 13, and the ejector 3 is also used for conveying CO₂The inlet pipe 4 of the waste gas is communicated, and a second valve 41 is arranged on the inlet pipe 4 and is used for regulating the CO content₂The flow rate of the exhaust gas.

The process flow for decalcifying by adopting the equipment comprises the following steps: adding light calcined powder calcium-leaching wastewater into the decalcification stirring tank 1 through the first liquid inlet hole 12, adding calcium-containing light calcined powder into the decalcification stirring tank through the first liquid inlet hole 11, mixing the light calcined powder calcium-leaching wastewater and the calcium-containing light calcined powder in the decalcification stirring tank 1 to form a mixed solution, allowing the mixed solution to enter the circulating pump 2 through the discharge hole 15, pumping the mixed solution into an inlet of the ejector 3 through the circulating pump 2, and pumping CO in the air inlet pipeline 4 by using the negative pressure pumping function of the ejector 3₂The waste gas is sucked into the ejector 3 to be fully mixed with the mixed solution, and then enters the decalcification stirring tank 1 through the second liquid inlet hole 13 to be decalcified.

After decalcification treatment, the calcium in the wastewater from calcium leaching of the light calcined powder can be effectively removed. As an optional embodiment of the invention, in the step (b), the calcium content in the decalcified solution is less than or equal to 0.3g/L, the magnesium content is 2-14 g/L, and the chlorine content is 2-45 g/L.

Typical but non-limiting calcium content in the post-decalcified liquor is 0.05g/L, 0.1g/L, 0.15g/L, 0.2g/L, 0.25g/L or 0.3 g/L; typical but non-limiting amounts of magnesium are 2.0g/L, 2.5g/L, 3.0g/L, 4.0g/L, 5.0g/L, 6.0g/L, 8.0g/L, 10.0g/L, 12.0g/L, or 14.0 g/L; typical but non-limiting chlorine contents are 2.0g/L, 3.0g/L, 4.0g/L, 5.0g/L, 6.0g/L, 8.0g/L, 10.0g/L, 15.0g/L, 20.0g/L, 25.0g/L, 30.0g/L, 35.0g/L, 40.0g/L, or 45.0 g/L.

The difference of the chlorine content in the decalcified liquid directly influences the subsequent application. As an alternative embodiment of the invention, in the step (c), when the chlorine content in the decalcified liquid is less than 20 g/L, for example, 0.5g/L, 1.0g/L, 2.0g/L, 3.0g/L, 4.0g/L, 5.0g/L, 8.0g/L, 10g/L, 15g/L, 18g/L, 19g/L or 19.9g/L, the decalcified liquid is concentrated to obtain concentrated water containing salt and fresh water containing salt; the salt-containing concentrated water is recycled as a leaching agent of the calcium-containing light calcined powder, and the salt-containing fresh water is recycled as washing water for solid-liquid separation after the calcium-containing light calcined powder is subjected to calcium leaching treatment;

or when the chlorine content in the decalcified liquid is 20-45g/L, such as 20.0g/L, 25.0g/L, 30.0g/L, 35.0g/L, 40.0g/L or 45.0g/L, the decalcified liquid is reused as the leaching agent of the calcium-containing light calcined powder.

As an alternative embodiment of the invention, the low-salt decalcified solution is subjected to a concentration treatment. In an alternative embodiment of the present invention, in the step (c), a reverse osmosis membrane is used for the concentration treatment.

The decalcified liquid is treated by a reverse osmosis membrane, so that the concentration of the magnesium chloride content in the low-salt decalcified liquid can be effectively realized.

The salt-containing fresh water subjected to concentration treatment contains lower salt content. As an optional embodiment of the invention, in the step (c), the content of chloride ions in the salt-containing fresh water is less than or equal to 2g/L, the content of calcium is less than or equal to 0.2g/L, and the content of magnesium is less than or equal to 0.7 g/L.

According to the second aspect of the invention, the application of the recycling method of the calcium leaching wastewater of the light calcined powder in the field of magnesium oxide preparation is also provided.

In view of the advantages of the recycling method of the calcium leaching wastewater of the light calcined powder, the method has good application in the field of magnesium oxide preparation.

The present invention will be further described with reference to specific examples and comparative examples.

Example 1

The embodiment provides a recycling method of calcium leaching wastewater of caustic soda powder, which comprises the following steps:

(a) providing calcium-containing calcined coke powder, and treating the calcined coke powder with a magnesium chloride leaching agent to form calcium-leaching wastewater of the calcined coke powder;

the calcium-containing light calcined powder is prepared by calcining magnesite in Gansu province, and the main element composition of the calcium leaching wastewater of the light calcined powder is shown in Table 1:

TABLE 1

(b) Soaking the light calcined powder into calcium wastewater for 10m³Pumping into a decalcification stirring tank, adding 230kg of calcium-containing light-burned powder into the decalcification stirring tank, starting a stirring device and a circulating pump of the decalcification stirring tank to pump a mixed solution formed by the calcium-soaking wastewater of the light-burned powder and the calcium-containing light-burned powder into an ejector through the circulating pump, and mixing the mixed solution with the water with the flow rate of 1700m³H of CO₂Mixing the waste gas in an ejector, and then feeding the waste gas into a decalcification stirring tank for decalcification, wherein the decalcification time is 4h, the temperature is 35 ℃, and the pH value of the decalcification is 7.5, so as to obtain a decalcification slurry; wherein it contains CO₂The waste gas is from magnesite calcination and is subjected to dust removal and temperature reduction treatment, and the waste gas contains CO₂CO in exhaust gas₂15% by volume;

carrying out solid-liquid separation on the decalcified slurry, specifically concentrating by adopting a thickener, and filtering and washing the bottom flow by adopting a horizontal filter press to obtain a decalcified liquid;

(c) detected every m³The consumption of the calcium-containing light burning powder (neutralizer) consumed by the light burning powder calcium-leaching wastewater is 23 kg; the calcium content and magnesium content in the decalcified liquid are respectively 0.15g/L and 0.15g/L11.12 g/L and 33.11g/L, and the chlorine content is higher, so the calcium-containing light calcined powder is recycled as a leaching agent of the calcium-containing light calcined powder.

Example 2

The embodiment provides a recycling method of calcium leaching wastewater of caustic soda powder, which comprises the following steps:

(a) providing calcium-containing calcined coke powder, and treating the calcined coke powder with a magnesium chloride leaching agent to form calcium-leaching wastewater of the calcined coke powder;

wherein, the calcium-containing light calcined powder is prepared by calcining certain Liaoning magnesite, and the main element composition of the calcium-leaching wastewater of the light calcined powder is shown in the table 2:

TABLE 2

(b) Soaking the light calcined powder into calcium wastewater for 10m³Pumping into a decalcification stirring tank, adding 49kg of calcium-containing light-burned powder into the decalcification stirring tank, starting a stirring device and a circulating pump of the decalcification stirring tank to pump a mixed solution formed by the calcium-soaking wastewater of the light-burned powder and the calcium-containing light-burned powder into an ejector through the circulating pump, and mixing the mixed solution with the water with the flow of 2300m³H of CO₂Mixing the waste gas in the ejector, and then feeding the waste gas into a decalcification stirring tank for decalcification, wherein the decalcification time is 6h, the temperature is 30 ℃, and the pH value of the decalcification is 8.0, so as to obtain a decalcification slurry; wherein it contains CO₂The waste gas is from magnesite calcination and is subjected to dust removal and temperature reduction treatment, and the waste gas contains CO₂CO in exhaust gas₂Is 5% by volume;

carrying out solid-liquid separation on the decalcified slurry, specifically concentrating by adopting a thickener, and filtering and washing the bottom flow by adopting a vacuum tape filter to obtain a decalcified liquid;

(c) detected every m³The consumption of the calcium-containing light burning powder (neutralizer) consumed by the light burning powder calcium-leaching wastewater is 4.9 kg; the calcium content in the decalcified liquid is 0.05g/L, the magnesium content is 1.78g/L, the chlorine content is 5.33g/L, and the decalcified liquid is pumped into a reverse osmosis system to be concentrated through a reverse osmosis membrane (a high-flux high-concentration brackish water desalination membrane) due to the low chlorine content, so that salt-containing concentrated water and salt-containing fresh water are obtained;

the chloride ion content in the salt-containing fresh water is 0.11g/L, the calcium content is 0.0011g/L, and the magnesium content is 0.038g/L, and the salt-containing fresh water is reused as washing water for solid-liquid separation after calcium-containing light calcined powder calcium leaching treatment; the content of chloride ions in the salt-containing concentrated water is 17.50g/L, the content of calcium is 0.16g/L, the content of magnesium is 5.84g/L, and the salt-containing concentrated water can be reused as a leaching agent of calcium-containing light calcined powder.

Example 3

The embodiment provides a recycling method of calcium leaching wastewater of caustic soda powder, which comprises the following steps:

(a) providing calcium-containing light calcined powder, and treating the light calcined powder with a brine leaching agent to form calcium-leaching wastewater of the light calcined powder;

wherein, the calcium-containing light calcined powder is prepared by calcining a dolomite ore in Hebei, and the main element composition of the calcium leaching wastewater of the light calcined powder is shown in Table 3:

TABLE 3

(b) Soaking the light calcined powder into calcium wastewater for 10m³Pumping into a decalcification stirring tank, adding 130kg of calcium-containing light-burned powder into the decalcification stirring tank, starting a stirring device and a circulating pump of the decalcification stirring tank, pumping mixed solution formed by calcium-soaking wastewater of the light-burned powder and the calcium-containing light-burned powder into an ejector through the circulating pump, and mixing the mixed solution with the water with the flow of 1065m³H of CO₂Mixing the waste gas in the ejector, and then feeding the waste gas into a decalcification stirring tank for decalcification, wherein the decalcification time is 5 hours, the temperature is 40 ℃, and the pH value of the decalcification is 7.8, so as to obtain a decalcification slurry; wherein it contains CO₂The waste gas is from dolomite ore calcination and is subjected to dust removal and temperature reduction treatment, and contains CO₂CO in exhaust gas₂Is 12% by volume;

carrying out solid-liquid separation on the decalcified slurry, specifically concentrating by adopting a thickener, and filtering and washing the bottom flow by adopting a vertical filter press to obtain a decalcified liquid;

(c) detected every m³The consumption of calcium-containing light burning powder (neutralizer) consumed by the light burning powder calcium-leaching wastewater is 13 kg; the calcium content of the decalcified liquid is 0.10g/L, the magnesium content is 5.80g/L, the chlorine content is 17.16g/L, and the decalcified liquid is pumped in due to the lower chlorine contentThe reverse osmosis system carries out concentration treatment through a reverse osmosis membrane to obtain salt-containing concentrated water and salt-containing fresh water;

the chloride ion content in the salt-containing fresh water is 0.49g/L, the calcium content is 0.003g/L, the magnesium content is 0.17g/L, and the salt-containing fresh water is reused as washing water for solid-liquid separation after calcium-containing light calcined powder calcium leaching treatment; the content of chloride ions in the salt-containing concentrated water is 56.06g/L, the content of calcium is 0.33g/L, the content of magnesium is 18.95g/L, and the salt-containing concentrated water can be reused as a leaching agent of calcium-containing light calcined powder.

Example 4

This example provides a recycling method of calcium-leaching wastewater of light calcined powder, except that in step (b), the calcium-containing light calcined powder is 380kg, the pH value of decalcification is 9.0, and the rest of steps (a) and (b) are the same as in example 1.

Step (c): detected every m³The dosage of the calcium-containing light burning powder (neutralizer) consumed by the light burning powder calcium-leaching wastewater is 38 kg; the calcium content in the decalcified liquid is 0.14g/L, the magnesium content is 12.54 g/L, the chlorine content is 33.09g/L, and the calcium content is higher, so that the calcium-containing light calcined powder is reused as a leaching agent of calcium-containing light calcined powder.

Example 5

This example provides a recycling method of calcium-leaching wastewater of light calcined powder, except that in step (b), the calcium-containing light calcined powder is 69 kg, the pH value of decalcification is 9.0, and the rest of steps (a) and (b) are the same as in example 2.

Step (c): detected every m³The dosage of the calcium-containing light burning powder (neutralizer) consumed by the light burning powder calcium-leaching wastewater is 6.9 kg; the calcium content of the decalcified liquid is 0.04g/L, the magnesium content is 1.85g/L, the chlorine content is 5.30g/L, and the decalcified liquid is pumped into a reverse osmosis system to be concentrated through a reverse osmosis membrane (a high-flux high-concentration brackish water desalination membrane) due to the low chlorine content, so that salt-containing concentrated water and salt-containing fresh water are obtained;

the chloride ion content in the salt-containing fresh water is 0.11g/L, the calcium content is 0.001 g/L, the magnesium content is 0.04g/L, and the salt-containing fresh water is reused as washing water for solid-liquid separation after calcium-containing light calcined powder calcium immersion treatment; the content of chloride ions in the salt-containing concentrated water is 17.4 g/L, the content of calcium is 0.13 g/L, the content of magnesium is 6.07 g/L, and the salt-containing concentrated water can be reused as a leaching agent of calcium-containing light calcined powder.

The decalcifying device adopted in the above embodiments 1 to 5 comprises a decalcifying stirring tank 1, a circulating pump 2 and an ejector 3, and the specific structure is shown in fig. 2;

be equipped with feed port 11 on the tank top of decalcification agitator tank 1, first feed inlet hole 12, second feed inlet hole 13 and exhaust hole 14, the tank bottom is equipped with relief hole 15, feed inlet hole 11 is arranged in adding calcium-containing light burning powder to decalcification agitator tank 1, first feed inlet hole 12 is arranged in adding the waste water that soaks calcium to the light burning powder in the decalcification agitator tank 1, second feed inlet hole 13 is used for realizing the intercommunication of sprayer 3 and decalcification agitator tank 1, exhaust hole 14 is used for discharging the waste gas after the decalcification of decalcification agitator tank 1, relief hole 15 is used for realizing the intercommunication of circulating pump 2 and decalcification agitator tank 1, still be equipped with the baffling board in the decalcification agitator tank 1.

Circulating pump 2 sets up in the outside of decalcification agitator tank 1, and discharge hole 15 and the 1 intercommunication of decalcification agitator tank are passed through to circulating pump 2's one end, and the other end passes through pipeline and sprayer 3 intercommunication. A first valve 21 for adjusting the flow rate of the liquid is provided in a pipe connecting the circulation pump 2 and the ejector 3.

The ejector 3 is arranged at the top of the decalcification stirring tank 1 and is communicated with the decalcification stirring tank 1 through a second liquid inlet hole 13, and the ejector 3 is also used for conveying CO₂The inlet pipe 4 of the waste gas is communicated, and a second valve 41 is arranged on the inlet pipe 4 and is used for regulating the CO content₂The flow rate of the exhaust gas.

Comparative example 1

The comparative example provides a recycling method of calcium leaching wastewater of caustic calcined powder, except that 10m of calcium leaching wastewater of caustic calcined powder is used in the step (b)³Pumping into a decalcification stirring tank, adding 230kg of calcium-containing light-burned powder into the decalcification stirring tank, starting a stirring device of the decalcification stirring tank, and controlling the flow rate to be 1700m³H of CO₂Introducing the waste gas into a stirring tank for decalcification (namely, the mixed solution of the calcium-soaking wastewater of the light calcined powder and the calcium-containing light calcined powder and CO₂The exhaust gases were not mixed in the ejector) and the rest of steps (a) and (b) were the same as in example 1.

Step (c): detected every m³The consumption of the calcium-containing light burning powder (neutralizer) consumed by the light burning powder calcium-leaching wastewater is 23 kg; after decalcificationThe calcium content in the liquid is 4.60g/L, the magnesium content is 8.45g/L, the chlorine content is 33.14g/L, and the calcium content is higher, so the calcium is not completely removed, and the calcium can not be reused as a leaching agent of the calcium-containing light calcined powder.

Comparative example 2

The comparative example provides a recycling method of calcium leaching wastewater of caustic calcined powder, except that 10m of calcium leaching wastewater of caustic calcined powder is used in the step (b)³Pumping into a decalcification stirring tank, adding 130kg of calcium-containing light-burned powder into the decalcification stirring tank, starting a stirring device of the decalcification stirring tank, and controlling the flow rate to be 1065m³H of CO₂Introducing the waste gas into a decalcifying stirring tank for decalcifying (namely, the mixed solution formed by the calcium-containing light-burned powder and the calcium-soaking waste water and the calcium-containing light-burned powder and CO₂The exhaust gases were not mixed in the ejector) and the rest of steps (a) and (b) were the same as in example 3.

Step (c): detected every m³The consumption of calcium-containing light burning powder (neutralizer) consumed by the light burning powder calcium-leaching wastewater is 13 kg; the calcium content of the decalcified liquid is 2.35g/L, the magnesium content is 4.41g/L, the chlorine content is 17.21g/L, and the decalcified liquid is pumped into a reverse osmosis system to be concentrated through a reverse osmosis membrane due to the low chlorine content, so that salt-containing concentrated water and salt-containing fresh water are obtained;

the chloride ion content in the salt-containing fresh water is 0.49g/L, the calcium content is 0.07 g/L, the magnesium content is 0.13 g/L, and the salt-containing fresh water is reused as washing water for solid-liquid separation after calcium-containing light calcined powder calcium immersion treatment; the content of chloride ions in the salt-containing concentrated water is 56.22 g/L, the content of calcium is 7.68 g/L, the content of magnesium is 14.41 g/L, and the content of calcium in the salt-containing concentrated water is higher, so that the salt-containing concentrated water cannot be reused as a leaching agent of the calcium-containing light calcined powder.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.