CN115385366B - Treatment method of magnesium-containing waste liquid - Google Patents
Treatment method of magnesium-containing waste liquid Download PDFInfo
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- CN115385366B CN115385366B CN202211062554.5A CN202211062554A CN115385366B CN 115385366 B CN115385366 B CN 115385366B CN 202211062554 A CN202211062554 A CN 202211062554A CN 115385366 B CN115385366 B CN 115385366B
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- 239000011777 magnesium Substances 0.000 title claims abstract description 88
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 title claims abstract description 77
- 229910052749 magnesium Inorganic materials 0.000 title claims abstract description 77
- 239000007788 liquid Substances 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 43
- 239000002699 waste material Substances 0.000 title claims abstract description 34
- 238000003763 carbonization Methods 0.000 claims abstract description 32
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910000022 magnesium bicarbonate Inorganic materials 0.000 claims abstract description 22
- QWDJLDTYWNBUKE-UHFFFAOYSA-L magnesium bicarbonate Chemical compound [Mg+2].OC([O-])=O.OC([O-])=O QWDJLDTYWNBUKE-UHFFFAOYSA-L 0.000 claims abstract description 20
- 239000002370 magnesium bicarbonate Substances 0.000 claims abstract description 20
- 235000014824 magnesium bicarbonate Nutrition 0.000 claims abstract description 20
- 238000000197 pyrolysis Methods 0.000 claims abstract description 17
- 239000000292 calcium oxide Substances 0.000 claims abstract description 16
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 16
- 238000000926 separation method Methods 0.000 claims abstract description 16
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims abstract description 15
- 230000001376 precipitating effect Effects 0.000 claims abstract description 13
- 239000007790 solid phase Substances 0.000 claims abstract description 13
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims abstract description 12
- 239000000920 calcium hydroxide Substances 0.000 claims abstract description 12
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims abstract description 12
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 12
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 11
- 238000002156 mixing Methods 0.000 claims abstract description 11
- 239000007791 liquid phase Substances 0.000 claims abstract description 10
- 239000002351 wastewater Substances 0.000 claims abstract description 9
- 238000004537 pulping Methods 0.000 claims abstract description 7
- 239000002893 slag Substances 0.000 claims abstract description 6
- 238000010000 carbonizing Methods 0.000 claims abstract description 4
- 239000000376 reactant Substances 0.000 claims abstract description 3
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 32
- 230000009467 reduction Effects 0.000 claims description 12
- 239000000571 coke Substances 0.000 claims description 8
- 239000002002 slurry Substances 0.000 claims description 7
- 239000002994 raw material Substances 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 2
- 239000003638 chemical reducing agent Substances 0.000 claims description 2
- 159000000003 magnesium salts Chemical class 0.000 abstract description 8
- 239000000706 filtrate Substances 0.000 description 35
- 239000000047 product Substances 0.000 description 20
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 15
- 239000000347 magnesium hydroxide Substances 0.000 description 15
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 238000001514 detection method Methods 0.000 description 14
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 13
- 238000001914 filtration Methods 0.000 description 13
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 13
- 239000001095 magnesium carbonate Substances 0.000 description 13
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 13
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 description 11
- 238000003756 stirring Methods 0.000 description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000001556 precipitation Methods 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 229910052938 sodium sulfate Inorganic materials 0.000 description 9
- 235000011152 sodium sulphate Nutrition 0.000 description 9
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 8
- 239000011575 calcium Substances 0.000 description 8
- 229910052602 gypsum Inorganic materials 0.000 description 8
- 239000010440 gypsum Substances 0.000 description 8
- 239000012535 impurity Substances 0.000 description 8
- 239000013078 crystal Substances 0.000 description 7
- 239000000395 magnesium oxide Substances 0.000 description 7
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 7
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 7
- 239000002244 precipitate Substances 0.000 description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 5
- 229910052791 calcium Inorganic materials 0.000 description 5
- 238000001035 drying Methods 0.000 description 5
- 230000002572 peristaltic effect Effects 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- NKWPZUCBCARRDP-UHFFFAOYSA-L calcium bicarbonate Chemical compound [Ca+2].OC([O-])=O.OC([O-])=O NKWPZUCBCARRDP-UHFFFAOYSA-L 0.000 description 4
- 229910000020 calcium bicarbonate Inorganic materials 0.000 description 4
- 229940095672 calcium sulfate Drugs 0.000 description 4
- 239000012065 filter cake Substances 0.000 description 4
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 229940095564 anhydrous calcium sulfate Drugs 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 230000001172 regenerating effect Effects 0.000 description 3
- 239000002352 surface water Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- QXZUUHYBWMWJHK-UHFFFAOYSA-N [Co].[Ni] Chemical compound [Co].[Ni] QXZUUHYBWMWJHK-UHFFFAOYSA-N 0.000 description 2
- 229910052925 anhydrite Inorganic materials 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 235000019341 magnesium sulphate Nutrition 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 229940057306 hemihydrate calcium sulfate Drugs 0.000 description 1
- 238000009854 hydrometallurgy Methods 0.000 description 1
- TUJKJAMUKRIRHC-UHFFFAOYSA-N hydroxyl Chemical compound [OH] TUJKJAMUKRIRHC-UHFFFAOYSA-N 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
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
- C01F5/24—Magnesium carbonates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
-
- 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
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/02—Oxides or hydroxides
- C01F11/08—Oxides or hydroxides by reduction of sulfates
-
- 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
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
-
- 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
- C01F5/06—Magnesia by thermal decomposition of magnesium compounds
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
- C01P2006/82—Compositional purity water content
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention discloses a method for treating magnesium-containing waste liquid, which comprises the following steps: s1: mixing a magnesium precipitating agent with magnesium-containing wastewater, carrying out solid-liquid separation, and collecting solid-phase slag; the temperature of the mixing is 95-100 ℃; the magnesium-containing wastewater contains Mg 2+ and SO 4 2‑; s2: pulping the solid-phase slag obtained in the step S1, carbonizing for one time, performing solid-liquid separation on carbonized products, and collecting liquid-phase components; s3: pyrolyzing the liquid phase component obtained in the step S2, carrying out solid-liquid separation on pyrolysis products, and collecting solid phase products; s4: performing secondary carbonization on the solid-phase product obtained in the step S3, and collecting liquid-phase components of the carbonized product to obtain magnesium bicarbonate refined liquid; the magnesium precipitating agent comprises at least one of calcium oxide and calcium hydroxide; the primary carbonization and the secondary carbonization are both contact of reactants and carbon dioxide. The treatment method of the magnesium-containing wastewater can effectively recover and produce high-purity magnesium salt.
Description
Technical Field
The invention belongs to the technical field of wastewater treatment, and particularly relates to a treatment method of magnesium-containing waste liquid.
Background
In the traditional hydrometallurgical process, the sulfuric acid leaching process is a common method for refining valuable metals. In nickel cobalt wet smelting, valuable metals such as nickel cobalt in ores are leached by sulfuric acid, a refined magnesium-containing sodium sulfate solution is obtained after extraction, separation and purification, then magnesium oxide is used for cobalt precipitation, a large amount of magnesium is contained in the solution, and then other metals are removed to obtain magnesium-containing sodium sulfate waste liquid.
At present, aiming at the treatment method of the magnesium-containing waste liquid, sodium hydroxide and sodium carbonate are often directly added into the magnesium-containing waste liquid, so as to obtain magnesium hydroxide/basic magnesium carbonate, and then the product is roasted into magnesium oxide and sold; or evaporating and concentrating the magnesium-containing waste liquid, freezing and crystallizing, and separating and purifying by the method to obtain magnesium sulfate and sodium sulfate crystals, and further preparing other magnesium salts. However, the method has the advantages of high raw and auxiliary material cost and poor economic benefit; evaporating, crystallizing, separating and purifying to easily form double salt, so that the quality of the obtained magnesium sulfate and sodium sulfate crystals is difficult to be ensured.
Therefore, it is an urgent need to develop a treatment method for recovering high-purity magnesium salt from magnesium-containing waste liquid.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides a treatment method of magnesium-containing waste liquid to prepare high-purity magnesium salt.
According to an embodiment of the first aspect of the present invention, a method for treating magnesium-containing waste liquid includes the steps of:
S1: mixing a magnesium precipitating agent with magnesium-containing wastewater, carrying out solid-liquid separation, and collecting solid-phase slag; the temperature of the mixing is 95-100 ℃; the magnesium-containing wastewater contains Mg 2+ and SO 4 2-;
S2: pulping the solid-phase slag obtained in the step S1, carbonizing for one time, performing solid-liquid separation on carbonized products, and collecting liquid-phase components;
S3: pyrolyzing the liquid phase component obtained in the step S2, carrying out solid-liquid separation on pyrolysis products, and collecting solid phase products;
s4: performing secondary carbonization on the solid-phase product obtained in the step S3, and collecting liquid-phase components of the carbonized product to obtain magnesium bicarbonate refined liquid;
the magnesium precipitating agent comprises at least one of calcium oxide and calcium hydroxide;
The primary carbonization and the secondary carbonization are both contact of reactants and carbon dioxide.
The principle of the invention is as follows:
In the step S1, magnesium hydroxide and calcium sulfate hemihydrate are obtained by controlling the addition of calcium oxide or calcium hydroxide, and filter residues obtained by filtering are calcium sulfate dihydrate and magnesium hydroxide;
Ca(OH)2+MgSO4+0.5H2O＝＝CaSO4·0.5H2O+Mg(OH)2；
CaO+MgSO4+1.5H2O＝＝CaSO4·0.5H2O+Mg(OH)2；
in the step S2, a magnesium bicarbonate solution containing a small amount of calcium bicarbonate is obtained through primary carbonization,
Mg(OH)2+2CO2＝＝Mg(HCO3)2；
In the step S3, pyrolyzing the magnesium bicarbonate solution in the liquid phase component filtered and separated in the step S2 to obtain basic magnesium carbonate (magnesium salt), wherein the magnesium salt preferentially enters the solution in the secondary carbonization process, and the content of magnesium in the solution is higher and higher, so that calcium and magnesium separation is realized, and the refined magnesium bicarbonate solution is obtained.
5Mg(HCO3)2＝4MgCO3·Mg(OH)2·4H2O+6CO2；
4MgCO3·Mg(OH)2·4H2O+CO2＝Mg(HCO3)2+3H2O；
The treatment method of the magnesium-containing waste liquid has at least the following beneficial effects:
1. At different temperatures, gypsum exists in different crystal products and crystal states, the dihydrate gypsum starts to release structural water at 65 ℃, but the dehydration speed is slower, and at 95-100 ℃, the filter residue can be converted into hemihydrate gypsum, meanwhile, the increase of energy consumption caused by overhigh temperature is avoided, the granularity of the hemihydrate calcium sulfate obtained by using the magnesium precipitation agent in the step S1 is good, the filtering performance is good, the surface entrained adhesion water is low, the water content of the whole product is reduced, the impurity entrainment is reduced, the product washing water consumption is reduced, and the product quality is improved; meanwhile, the drying cost of subsequent products can be reduced.
2. The primary carbonization is to convert magnesium hydroxide into magnesium bicarbonate solution to realize separation from solid-phase calcium sulfate, a small amount of calcium enters the solution in the process, and the secondary carbonization removes calcium to obtain refined magnesium bicarbonate solution, and the secondary carbonization can remove impurities such as calcium and the like.
3. The invention realizes the extraction of magnesium and the separation of magnesium and calcium by secondary carbonization, effectively recovers and produces high-purity magnesium salt, and also realizes the fixation and utilization of carbon dioxide, and effectively recovers and produces high-purity magnesium salt.
According to some embodiments of the invention, the mixing comprises feed mixing by peristaltic pump.
According to some embodiments of the invention, the peristaltic pump feed rate is 0.001 to 0.009mol/min on a molar basis.
The feeding speed is too high, so that agglomeration phenomenon is generated when powder enters the solution, the surface of the agglomerate is covered by generated sediment after the reaction, the materials in the reactor are not reacted any more, and the reaction efficiency is reduced.
According to some embodiments of the invention, the molar ratio of Mg 2+ in the magnesium-containing wastewater to the magnesium-precipitating agent is 1: (1.05-1.1).
The magnesium precipitating agent is added according to the proportion, so that the magnesium precipitation is ensured to be complete, meanwhile, the magnesium precipitating agent can be prevented from entering the product due to excessive consumption of the magnesium precipitating agent, and the impurity content of the product is increased.
According to some embodiments of the invention, the mixing comprises stirring mixing.
According to some embodiments of the invention, the stirring and mixing speed is 50-300 r/min.
At the rotating speed, the granularity and the crystal form of the calcium sulfate hemihydrate are ensured, so that better filtering performance is ensured, and the consumption of water for washing filter residues is reduced.
According to some embodiments of the invention, the calcium sulfate hemihydrate has a particle size Dv50 of 50-80 μm.
According to some embodiments of the invention, in step S1, the main component of the filtrate obtained after the solid-liquid separation is sodium sulfate.
The sodium sulfate can be evaporated and crystallized to prepare anhydrous sodium sulfate for sale.
According to some embodiments of the invention, in step S2, the solid content of the pulped slurry is 10% -20%.
The slurry with the solid content has good fluidity, and does not introduce excessive water and increase the subsequent treatment procedures.
According to some embodiments of the invention, the pH of the system after the primary carbonization is 7.0-7.5.
At the pH value, the magnesium in the system is fully converted into magnesium bicarbonate.
According to some embodiments of the invention, in step S3, the pyrolysis temperature is 60-65 ℃.
According to some embodiments of the invention, in step S3, the termination condition of the secondary carbonization is that the concentration change rate of Mg 2+ in the carbonized liquid is equal to or less than 0.01g/L.
Stopping carbonization when the concentration of Mg 2+ in the carbonized liquid tends to be stable, and obtaining the carbonized liquid which is magnesium bicarbonate refined liquid.
According to some embodiments of the invention, in step S4, pyrolysis of the magnesium bicarbonate refined solution is further included.
According to some embodiments of the invention, the pyrolysis temperature of the magnesium bicarbonate refined solution is 90-95 ℃.
According to some embodiments of the invention, the pyrolysis time of the magnesium bicarbonate refined solution is 1-2 hours.
According to some embodiments of the invention, basic magnesium carbonate is obtained after pyrolysis of the magnesium bicarbonate refined solution.
According to some embodiments of the invention, the method further comprises drying and roasting the basic magnesium carbonate to obtain active magnesium oxide.
According to some embodiments of the invention, carbon dioxide generated during the calcination process may be recycled to the primary and secondary carbonization processes.
According to some embodiments of the invention, in step S2, the method further comprises pyrolysis reduction of the filter residue obtained by the solid-liquid separation into the magnesium precipitating agent.
According to some embodiments of the invention, the filter residue comprises calcium sulfate.
According to some embodiments of the invention, the pyrolysis reduction is preceded by drying the filter residue.
According to some embodiments of the invention, the drying temperature is 150-250 ℃.
According to some embodiments of the invention, the reducing agent used for pyrolytic reduction of the filter residue comprises coke.
According to some embodiments of the invention, the pyrolysis reduction temperature is 1000-1300 ℃.
According to some embodiments of the invention, the raw materials for pyrolysis reduction are prepared from the following materials in percentage by weight: calcium sulfate= (0.15 to 0.2): 1.
The method can realize the recycling of the magnesium precipitation agent, greatly save the consumption of raw materials and auxiliary materials and realize the recycling economy.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a flow chart of the treatment process of magnesium-containing waste liquid in example 1 of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
Example 1
The embodiment discloses a method for treating magnesium-containing waste liquid, which comprises the following specific steps:
s1: taking waste liquid containing 7g/L magnesium; preparing 100g/L calcium hydroxide slurry, feeding slowly by a peristaltic pump according to a molar ratio of 1:1.05, stirring and reacting for 1.5 hours at 95 ℃ to obtain magnesium hydroxide and calcium sulfate hemihydrate, regenerating calcium sulfate dihydrate when the calcium sulfate hemihydrate is filtered and separated, filtering, and further removing impurities from the filtrate to obtain anhydrous sodium sulfate, wherein the main component is sodium sulfate, and the filtrate is shown in a table 1.
S2: the solid-to-liquid ratio of calcium sulfate dihydrate and magnesium hydroxide in the step S1 is controlled to be 15%, water is added for pulping, carbon dioxide is introduced for primary carbonization at 25 ℃, after filtration, the filter cake component is mainly calcium sulfate dihydrate, the filtrate is magnesium bicarbonate and a small amount of residual calcium bicarbonate, the detection result of primary carbonization filtrate is shown in the table 2, the calcium sulfate dihydrate (gypsum) is dried at 200 ℃ to obtain anhydrous calcium sulfate, the roasting temperature is controlled to 1200 ℃, and coke is added to obtain coke: gypsum 0.15:1, through reduction roasting and decomposition, sulfuric acid can be prepared, and meanwhile, calcium oxide/calcium hydroxide is co-produced, and the detection result of the obtained calcium oxide is shown in table 5 and is used as a raw material for magnesium precipitation.
S3: pyrolyzing the primary carbonized filtrate to obtain magnesium carbonate precipitate, stirring the magnesium carbonate precipitate at a solid-to-liquid ratio of 20%, performing secondary carbonization to obtain magnesium bicarbonate solution, filtering, detecting the secondary carbonized filtrate, pyrolyzing the secondary carbonized filtrate to obtain basic magnesium carbonate, roasting to obtain magnesium oxide, and recovering tail gas carbon dioxide, wherein the detection result of the secondary carbonized filtrate is shown in table 3.
The process flow diagram of the treatment of magnesium-containing waste liquid in this embodiment is shown in fig. 1.
Example 2
The embodiment discloses a method for treating magnesium-containing waste liquid, which comprises the following specific steps:
s1: taking waste liquid containing 7g/L magnesium; preparing 100g/L calcium hydroxide slurry, feeding slowly by a peristaltic pump according to a molar ratio of 1:1, stirring and reacting for 1.5 hours at 95 ℃ to obtain magnesium hydroxide and calcium sulfate hemihydrate, regenerating calcium sulfate dihydrate during filtering and separating, filtering, detecting filtrate with sodium sulfate as a main component, and removing impurities from the filtrate to obtain anhydrous sodium sulfate.
S2: the solid-to-liquid ratio of calcium sulfate dihydrate and magnesium hydroxide in the step S1 is controlled to be 15%, water is added for pulping, carbon dioxide is introduced for primary carbonization at 25 ℃, after filtration, the filter cake component is mainly calcium sulfate dihydrate, the filtrate is magnesium bicarbonate and a small amount of residual calcium bicarbonate, the detection result of primary carbonization filtrate is shown in the table 2, the calcium sulfate dihydrate (gypsum) is dried at 180 ℃ to obtain anhydrous calcium sulfate, the roasting temperature is controlled to 1250 ℃, and coke is added: gypsum 0.18:1, through reduction roasting and decomposition, sulfuric acid can be prepared, and meanwhile, calcium oxide/calcium hydroxide is co-produced, and the detection result of the obtained calcium oxide is shown in table 5 and is used as a raw material for magnesium precipitation.
S3: pyrolyzing the primary carbonized filtrate to obtain magnesium carbonate precipitate, stirring the magnesium carbonate precipitate at a solid-to-liquid ratio of 15%, performing secondary carbonization to obtain magnesium bicarbonate solution, filtering, detecting the secondary carbonized filtrate, pyrolyzing the secondary carbonized filtrate to obtain basic magnesium carbonate, roasting to obtain magnesium oxide, and recovering tail gas carbon dioxide, wherein the detection result of the secondary carbonized filtrate is shown in table 3.
Example 3
The embodiment discloses a method for treating magnesium-containing waste liquid, which comprises the following specific steps:
S1: taking waste liquid containing 7g/L magnesium; preparing 100g/L calcium hydroxide slurry, feeding slowly by a peristaltic pump according to a molar ratio of 1:1.1, stirring and reacting for 1.5 hours at 95 ℃ to obtain magnesium hydroxide and calcium sulfate hemihydrate, regenerating calcium sulfate dihydrate when the calcium sulfate hemihydrate is filtered and separated, filtering, and further removing impurities from the filtrate to obtain anhydrous sodium sulfate, wherein the main component is sodium sulfate, and the filtrate is shown in a table 1.
S2: the solid-to-liquid ratio of calcium sulfate dihydrate and magnesium hydroxide in the step S1 is controlled to be 10%, water is added for pulping, carbon dioxide is introduced for primary carbonization at 25 ℃, after filtration, the filter cake component is mainly calcium sulfate dihydrate, the filtrate is magnesium bicarbonate and a small amount of residual calcium bicarbonate, the detection result of primary carbonization filtrate is shown in the table 2, the calcium sulfate dihydrate (gypsum) is dried at 250 ℃ to obtain anhydrous calcium sulfate, the roasting temperature is controlled to 1300 ℃, and coke is added to obtain coke: gypsum 0.2:1, through reduction roasting and decomposition, sulfuric acid can be prepared, and meanwhile, calcium oxide/calcium hydroxide is co-produced, and the detection result of the obtained calcium oxide is shown in table 5 and is used as a raw material for magnesium precipitation.
S3: pyrolyzing the primary carbonized filtrate to obtain magnesium carbonate precipitate, stirring the magnesium carbonate precipitate at a solid-to-liquid ratio of 10%, performing secondary carbonization to obtain magnesium bicarbonate solution, filtering, detecting the secondary carbonized filtrate, pyrolyzing the secondary carbonized filtrate to obtain basic magnesium carbonate, roasting to obtain magnesium oxide, and recovering tail gas carbon dioxide, wherein the detection result of the secondary carbonized filtrate is shown in table 3.
Example 4
The embodiment discloses a method for treating magnesium-containing waste liquid, which is different from embodiment 1 in that in step S1, the temperature of stirring reaction is 100 ℃, the other conditions are the same, and the specific steps are as follows:
Comparative example 1
This comparative example discloses a method for treating magnesium-containing waste liquid, which is different from example 1 in that the stirring reaction temperature in step S1 in this comparative example is 85 deg.c, and the other conditions are the same as in example 1.
Comparative example 2
This comparative example discloses a method for treating magnesium-containing waste liquid, which is different from example 1 in that the stirring reaction temperature in step S1 in this comparative example is 90 deg.c, and the other conditions are the same as in example 1.
Test example 1
In this test example, the filtrates in step S1 of examples 1 to 3 were subjected to the test, and the test results are shown in table 1.
TABLE 1 detection results of magnesium precipitation filtrate
| S(g/L) | Na(g/L) | Ca(g/L) | Mg(g/L) | CO3 2-(g/L) | |
| Example 1 | 32.92 | 41.86 | 0.55 | 0.0001 | 0.0001 |
| Example 2 | 32.92 | 42.19 | 0.54 | 0.796 | 0.175 |
| Example 3 | 30.81 | 41.03 | 0.66 | 0.0001 | 1.83 |
| Example 4 | 32.90 | 41.83 | 0.53 | 0.0001 | 0.0001 |
Test example 2
This test example was conducted on the magnesium precipitation residue in step S1 of example 1 and comparative examples 1-2, and the test results are shown in table 2.
TABLE 2 detection results of magnesium deposition filter residues
In the embodiment 2 in the table 1, calcium hydroxide slurry is added according to the feeding ratio of 1:1, and the reaction proportion cannot reach 100%, trace loss exists in the process, and the concentration of hydroxyl radical in the magnesium-containing waste liquid cannot reach the concentration of completely precipitated magnesium, so that the concentration of magnesium in the filtrate is higher than that of other two groups of embodiments.
In Table 2, the reaction temperatures in comparative examples 1 and 2 are 85 ℃ and 90 ℃, the filter residue products are mainly calcium sulfate dihydrate, the crystal water and the surface water of the filter residue products are higher than those of the filter residue obtained in example 1, and the content of impurities carried on the surface is high, and the sodium content is more than 1.5%; the reaction temperature of example 1 was 95 ℃, the residue product was mainly hemihydrate gypsum, the crystal water and surface water contents were lower than those of comparative examples 1 and 2, and the sodium content was only 0.1% and was also far lower than those of comparative examples 1 and 2.
Test example 3
In this test example, the primary carbonized filtrate in step S2 of examples 1 to 3 was subjected to the test, and the test results are shown in table 3.
TABLE 3 detection results of primary carbonized filtrate
| S(g/L) | Na(g/L) | Ca(g/L) | Mg(g/L) | |
| Example 1 | 6.03 | 0.19 | 0.17 | 13.25 |
| Example 2 | 8.04 | 0.2527 | 0.23 | 16.22 |
| Example 3 | 10.52 | 0.3627 | 0.33 | 20.22 |
Test example 4
In this test example, the secondary carbonized filtrate in step S3 of examples 1 to 3 was subjected to the test, and the test results are shown in table 4.
TABLE 4 detection results of secondary carbonized filtrate
| S(g/L) | Na(g/L) | Ca(g/L) | Mg(g/L) | |
| Example 1 | 6.27 | 0.18 | 0.01 | 12.44 |
| Example 2 | 8.35 | 0.24 | 0.01 | 16.18 |
| Example 3 | 10.33 | 0.34 | 0.01 | 21.18 |
Pulping and carbonizing filter cakes according to different solid-to-liquid ratios, wherein the magnesium content in the reaction is basically the same, the lower the solid-to-liquid ratio is, the higher the magnesium concentration in filtrate after carbonization is, the carbonization is carried out according to 10% in the solid-to-liquid ratio in the embodiment 3, the highest magnesium recovery rate in the filtrate is achieved, and the process is the best in recovery benefit compared with the embodiment.
Test example 5
In this test example, the primary carbonized filtrate in step S3 of examples 1 to 3 was subjected to the test, and the test results are shown in table 5.
TABLE 5 calcium sulfate dihydrate results
The calcium sulfate dihydrate obtained by the method has low surface water content, and the water content of the conventional calcium sulfate dihydrate is more than 20 percent below 7 percent, so that the surface entrained adhesive water of the calcium sulfate dihydrate is low, the water content of the whole product is reduced, the entrainment of impurities is reduced, the consumption of washing water of the product is reduced, and the quality of the product is improved; meanwhile, the drying cost of subsequent products can be reduced.
Test example 6
In this test example, the calcium oxide obtained in step S2 of examples 1 to 3 was tested, and the test results are shown in table 6.
TABLE 6 calcium oxide detection results
The calcium oxide is obtained by pyrolysis reduction of calcium sulfate, is suitable for the standard of industrial calcium oxide for I-type chemical synthesis in HG/T4205-2011, has the calcium oxide content of more than or equal to 92 percent and the magnesium oxide content of less than or equal to 1.5 percent, and can be used as a magnesium precipitating agent to be added into magnesium-containing waste liquid for recycling.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present invention.
Claims (9)
1. The method for treating the magnesium-containing waste liquid is characterized by comprising the following steps of:
S1: mixing a magnesium precipitating agent with magnesium-containing wastewater, carrying out solid-liquid separation, and collecting solid-phase slag; the temperature of the mixing is 95-100 ℃; the magnesium-containing wastewater contains Mg 2+ and SO 4 2-;
S2: pulping the solid-phase slag obtained in the step S1, carbonizing for one time, performing solid-liquid separation on carbonized products, and collecting liquid-phase components;
S3: pyrolyzing the liquid phase component obtained in the step S2, carrying out solid-liquid separation on pyrolysis products, and collecting solid phase products;
s4: performing secondary carbonization on the solid-phase product obtained in the step S3, and collecting liquid-phase components of the carbonized product to obtain magnesium bicarbonate refined liquid;
the magnesium precipitating agent comprises at least one of calcium oxide and calcium hydroxide;
the primary carbonization and the secondary carbonization are both contact of reactants and carbon dioxide;
The molar ratio of Mg 2+ in the magnesium-containing wastewater to the magnesium precipitating agent is 1: (1.05-1.1);
in the step S2, the method further comprises the step of pyrolyzing and reducing filter residues obtained by the solid-liquid separation into the magnesium precipitating agent.
2. The method for treating magnesium-containing waste liquid according to claim 1, wherein in the step S2, the solid content of the pulped slurry is 10% to 20%.
3. The method for treating magnesium-containing waste liquid according to claim 1, wherein the pH value after the primary carbonization is 7.0 to 7.5.
4. The method for treating magnesium-containing waste liquid according to claim 1, wherein the termination condition of the secondary carbonization is that a concentration change rate of Mg 2+ in the carbonized liquid is 0.01g/L or less.
5. The method for treating magnesium-containing waste liquid according to claim 1, wherein in the step S3, the pyrolysis temperature is 60 to 65 ℃.
6. The method for treating magnesium-containing waste liquid according to claim 1, wherein the filter residue comprises calcium sulfate.
7. The method for treating magnesium-containing waste liquid according to claim 6, wherein the reducing agent used for the pyrolysis reduction comprises coke.
8. The method for treating magnesium-containing waste liquid according to claim 7, wherein the raw material ratio of pyrolysis reduction is, by weight, that of coke: calcium sulfate= (0.15 to 0.2): 1.
9. The method for treating magnesium-containing waste liquid according to claim 8, wherein the pyrolysis reduction temperature is 1000 to 1300 ℃.
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| CN101760646A (en) * | 2008-12-24 | 2010-06-30 | 中国恩菲工程技术有限公司 | Leaching method of magnesium-containing ore |
| CN106277417A (en) * | 2015-05-26 | 2017-01-04 | 有研稀土新材料股份有限公司 | The method that smelting waste water comprehensive containing magnesium reclaims |
| CN107098366A (en) * | 2017-04-25 | 2017-08-29 | 中国恩菲工程技术有限公司 | The method for handling magnesium-containing waste solution |
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| CN101104522A (en) * | 2007-06-05 | 2008-01-16 | 昆明贵金属研究所 | Method for preparing active magnesium chloride by using magnesium sulfate waste liquid |
| CN101519219A (en) * | 2008-02-26 | 2009-09-02 | 中国恩菲工程技术有限公司 | Manufacturing process for light magnesium carbonate |
| CN101760641B (en) * | 2008-12-24 | 2011-08-10 | 中国恩菲工程技术有限公司 | Technology for recovering magnesium from magnesium sulfate solution |
| KR101663515B1 (en) * | 2015-01-08 | 2016-10-07 | 전남대학교산학협력단 | Method for manufacturing hydrated magnesium carbonate |
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| CN101760646A (en) * | 2008-12-24 | 2010-06-30 | 中国恩菲工程技术有限公司 | Leaching method of magnesium-containing ore |
| CN106277417A (en) * | 2015-05-26 | 2017-01-04 | 有研稀土新材料股份有限公司 | The method that smelting waste water comprehensive containing magnesium reclaims |
| CN107098366A (en) * | 2017-04-25 | 2017-08-29 | 中国恩菲工程技术有限公司 | The method for handling magnesium-containing waste solution |
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| 王志强等."以轻烧白云石为原料二次碳化法制备高纯碱式碳酸镁".《硅酸盐学报》.第第41卷卷(第第10期期),第1438页第3-7段和图1. * |
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