CN112520765B - Recycling method and application of calcium leaching wastewater of light calcined powder - Google Patents
Recycling method and application of calcium leaching wastewater of light calcined powder Download PDFInfo
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- CN112520765B CN112520765B CN202110174403.8A CN202110174403A CN112520765B CN 112520765 B CN112520765 B CN 112520765B CN 202110174403 A CN202110174403 A CN 202110174403A CN 112520765 B CN112520765 B CN 112520765B
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- calcium
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- calcined powder
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- 239000011575 calcium Substances 0.000 title claims abstract description 229
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 title claims abstract description 223
- 229910052791 calcium Inorganic materials 0.000 title claims abstract description 223
- 239000000843 powder Substances 0.000 title claims abstract description 180
- 238000002386 leaching Methods 0.000 title claims abstract description 143
- 239000002351 wastewater Substances 0.000 title claims abstract description 100
- 238000000034 method Methods 0.000 title claims abstract description 56
- 238000004064 recycling Methods 0.000 title claims abstract description 48
- 239000007788 liquid Substances 0.000 claims abstract description 92
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 46
- 239000002912 waste gas Substances 0.000 claims abstract description 44
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 44
- 238000000926 separation method Methods 0.000 claims abstract description 26
- 239000011259 mixed solution Substances 0.000 claims abstract description 23
- 238000002156 mixing Methods 0.000 claims abstract description 19
- 238000005406 washing Methods 0.000 claims abstract description 17
- 239000002002 slurry Substances 0.000 claims abstract description 16
- 239000000395 magnesium oxide Substances 0.000 claims abstract description 15
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims abstract description 15
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000002360 preparation method Methods 0.000 claims abstract description 9
- 150000003839 salts Chemical class 0.000 claims description 46
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 30
- 239000000460 chlorine Substances 0.000 claims description 30
- 229910052801 chlorine Inorganic materials 0.000 claims description 30
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 29
- 239000011777 magnesium Substances 0.000 claims description 29
- 229910052749 magnesium Inorganic materials 0.000 claims description 29
- 239000007789 gas Substances 0.000 claims description 28
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 claims description 24
- 239000013505 freshwater Substances 0.000 claims description 24
- 239000001095 magnesium carbonate Substances 0.000 claims description 18
- 235000014380 magnesium carbonate Nutrition 0.000 claims description 18
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 claims description 18
- 229910000021 magnesium carbonate Inorganic materials 0.000 claims description 18
- 238000001354 calcination Methods 0.000 claims description 17
- 229910001629 magnesium chloride Inorganic materials 0.000 claims description 12
- 238000001223 reverse osmosis Methods 0.000 claims description 12
- 239000012528 membrane Substances 0.000 claims description 10
- 239000010459 dolomite Substances 0.000 claims description 9
- 229910000514 dolomite Inorganic materials 0.000 claims description 9
- 239000012267 brine Substances 0.000 claims description 7
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 7
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 6
- 239000000347 magnesium hydroxide Substances 0.000 claims description 6
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 6
- 229940075397 calomel Drugs 0.000 claims 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical compound Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 claims 1
- 239000000243 solution Substances 0.000 abstract description 19
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 abstract description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 9
- 239000012716 precipitator Substances 0.000 abstract description 5
- 235000011121 sodium hydroxide Nutrition 0.000 abstract description 4
- 229910052799 carbon Inorganic materials 0.000 abstract description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 49
- 238000003756 stirring Methods 0.000 description 36
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 27
- 239000001569 carbon dioxide Substances 0.000 description 13
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 12
- 238000002791 soaking Methods 0.000 description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 10
- 239000011329 calcined coke Substances 0.000 description 9
- 238000005086 pumping Methods 0.000 description 9
- 239000003518 caustics Substances 0.000 description 7
- 229910000019 calcium carbonate Inorganic materials 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 239000003054 catalyst Substances 0.000 description 3
- 239000000428 dust Substances 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 239000002562 thickening agent Substances 0.000 description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000010612 desalination reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- -1 hydrogen ions Chemical class 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 238000011031 large-scale manufacturing process Methods 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 230000003472 neutralizing effect Effects 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/02—Magnesia
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2/00—Lime, magnesia or dolomite
- C04B2/10—Preheating, burning calcining or cooling
- C04B2/102—Preheating, burning calcining or cooling of magnesia, e.g. dead burning
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Ceramic Engineering (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Inorganic Chemistry (AREA)
- Geology (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Removal Of Specific Substances (AREA)
- Treating Waste Gases (AREA)
Abstract
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 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 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 utilized2The 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; 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.
Description
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 of calcium leaching of the light calcined powder is higher, about 2.5-15g/L, and the waste water can not be discharged outside nor 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 CO2Flow rate of exhaust gas according to formula(1) And (3) calculating:
Q =(mCa×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 isCaThe 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 20g/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 gas2Exhaust gas andthe calcium-containing light calcined powder is 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 liquid and the CO-containing mixed liquid2The 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, recycling the light calcined powderMixed liquor formed by calcium-soaking waste water of calcined powder and calcium-containing light calcined powder and 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 =(mCa×0.56×n)/(V×t) （1）
wherein Q is CO2Flow rate of exhaust gas in cubic meter per hour (m)3/h）；mCaThe 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 20g/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 gas 215% 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 in the decalcified liquid is 0.15g/L, the magnesium content is 11.12 g/L, the chlorine content is 33.11g/L, and the calcium content is higher, so the calcium-containing light calcined powder is reused as a leaching agent of 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 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 0.003g/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; the calcium content in the decalcified 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-burned 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 to decalcify (namely the waste of soaking calcium by light burning powder)Mixed liquid of water and 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.
Claims (6)
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; wherein the mass of calcium in the calcium-containing calcined dolomite is 0.5-3 times of that of the calcium in the calcined dolomite calcium-leaching wastewater; containing CO2The exhaust gas including magnesium ore is generated during calcinationThe waste gas and/or the waste gas generated in the calcining process of the magnesium hydroxide formed by the calcium leaching treatment of the calcium-containing light calcined powder by the leaching agent contains CO2CO in exhaust gas2The volume fraction of (A) is 1-30%; the decalcification time is 2-15h, the decalcification temperature is 20-50 ℃, and the pH value of the decalcification is 7.0-8.5;
carrying out solid-liquid separation on the decalcified slurry to obtain a decalcified liquid;
(c) the decalcified liquid is used 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, and the method comprises the following steps:
when the chlorine content in the decalcified liquid is less than 20g/L, 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.
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 waste water from the calcium leaching of the light calcined powder as claimed in claim 1, wherein in the step (b), the waste water contains CO2The flow rate of the exhaust gas is calculated according to equation (1):
Q＝(mCa×0.56×n)/(V×t) (1)
wherein Q is CO2Of exhaust gasesFlow rate in cubic meters per hour; m isCaThe 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.
5. 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 (c), a reverse osmosis membrane is used for concentration treatment.
6. The application of the recycling method of the waste water from the calcium leaching of the light calcined powder as claimed in any one of claims 1 to 5 in the field of the preparation of magnesium oxide.
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| CN111732115A (en) * | 2020-07-07 | 2020-10-02 | 辽宁镁誉新材料股份有限公司 | Preparation method and application of metallurgical precipitation grade magnesium oxide |
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| US4937056A (en) * | 1986-06-20 | 1990-06-26 | Materials-Concepts-Research Limited | Process for obtaining high purity magnesium compounds from magnesium containing materials |
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| KR101722963B1 (en) * | 2016-03-08 | 2017-04-04 | 태경화학 주식회사 | Method For Producing Magnesium Hydroxide Powder By Semidry Process |
| CN107417146A (en) * | 2017-07-18 | 2017-12-01 | 沈阳化工大学 | A kind of low-grade magnesite method of comprehensive utilization |
| CN110921688A (en) * | 2019-12-16 | 2020-03-27 | 北京矿冶科技集团有限公司 | Active magnesium oxide and preparation method and application thereof |
| CN111732115A (en) * | 2020-07-07 | 2020-10-02 | 辽宁镁誉新材料股份有限公司 | Preparation method and application of metallurgical precipitation grade magnesium oxide |
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Address after: Building 23, area 18, headquarters base, 188 South Fourth Ring Road West, Fengtai District, Beijing Patentee after: Mining and Metallurgical Technology Group Co.,Ltd. Country or region after: China Patentee after: Gansu Magnesium Hong Technology Co.,Ltd. Address before: Building 23, area 18, headquarters base, 188 South Fourth Ring Road West, Fengtai District, Beijing Patentee before: Mining and Metallurgical Technology Group Co.,Ltd. Country or region before: China Patentee before: SUBEI HIGH-TECH MAGNESIA CO.,LTD. |