CN115448329A - Process for refining ammonia-soda enterprise brine without three wastes - Google Patents
Process for refining ammonia-soda enterprise brine without three wastes Download PDFInfo
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- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
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- 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
- C01F11/18—Carbonates
- C01F11/181—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions
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- C—CHEMISTRY; METALLURGY
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- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
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- C01F5/24—Magnesium carbonates
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Abstract
The invention provides a saline water refining process of an ammonia-soda enterprise without generating three wastes, belonging to the technical field of three-waste treatment and comprehensive use in the ammonia-soda industry. The refining process disclosed by the invention is established through an ammonia-soda production process system, and the recycling of the brine refining primary magnesium removal mud and the integration of a carbon dioxide curing system are realized, so that the harmless value-added utilization of the thermoelectric flue gas carbon reduction and the brine refining primary magnesium removal mud is realized; the whole process not only realizes zero emission of the primary magnesium removal mud for brine refining, but also does not generate new three wastes, thereby realizing virtuous cycle.
Description
Technical Field
The invention relates to a brine refining process for ammonia-soda enterprises, belonging to the technical field of three-waste treatment and comprehensive use in ammonia-soda industry.
Background
At present, some soda production enterprises adopt a technology of discharging concentrated seawater hydrated salt in a seawater desalination process, so that on one hand, the pollution of the concentrated seawater directly discharged to the environment is prevented, on the other hand, sodium salt in seawater is recovered, the soda production cost is reduced, and the raw material source is expanded. Because the content of calcium and magnesium impurities in the crude brine after the concentrated seawater is salted is high, the brine is refined by sequentially adding lime, mirabilite and soda ash to remove the impurities. Primary magnesium-removing mud and secondary calcium-removing mud are generated in the refining process, wherein the primary magnesium-removing mud mainly comprisesAre divided into Mg (OH) 2 、CaCO 3 、CaSO 4 The annual output is about 50 ten thousand tons, and the secondary calcium-removing mud is used for preparing calcium carbonate products. The primary magnesium-removing mud treatment mode for brine refining is mainly filter-pressing stockpiling at present, and the treatment mode occupies a large amount of land to generate certain influence on the ecological environment on one hand and causes waste of calcium and magnesium resources on the other hand, so that the recycling, harmless and high-added-value treatment of the primary magnesium-removing mud for brine refining is one of the major subjects faced by the soda production at present.
In addition, the flue gas of the thermoelectric company is subjected to denitration and desulfurization and then is discharged up to the standard, wherein a large amount of CO is contained 2 And (4) resources. The current mainstream industrial technologies include adsorption, absorption, membrane separation and biological methods, which have good effects but low cost and are economical.
Therefore, a new process is urgently needed, which couples the soda brine refining primary magnesium removal sludge treatment and the thermoelectric CO 2 Realizes 'treating waste by waste', high-efficiency recovery of calcium and magnesium resources, and CO 2 Emission reduction and comprehensive utilization, the recycling economy industrial chain of enterprises is extended, a model of the soda ash and thermoelectric waste cooperative treatment industry is created, the technological progress of the industry is promoted, and the green sustainable development of the traditional salt chemical industry and related industries in our province is promoted.
Some researches have been carried out at home and abroad on the comprehensive utilization of primary magnesium-removing mud in brine refining. For example, patent CN109574055B proposes to react salt slurry with flue gas to produce magnesium sulfate and calcium carbonate, but this method does not consider the problem of separation and purification of calcium and magnesium in magnesium sulfate solution, which results in low purity of the following magnesium series products, and in addition, the reaction time is long, resulting in large and large amount of equipment in the process. Patent CN1137488A proposes sulfuric acid acidification of chlor-alkali salt slurry for extracting magnesium, and this method consumes more sulfuric acid and has higher cost. CN101219328A proposes that the salt slurry is used for sulfur dioxide desulfurization in flue gas, and byproducts of magnesium sulfate and calcium sulfate are produced. Domestic and foreign researches mainly focus on one-step reaction of the salt slurry, the whole process from the salt slurry to a magnesium product is not formed, and the calcium and magnesium separation process is not thorough enough, so that the calcium content in the magnesium product is high.
Disclosure of Invention
Aiming at the problems, the invention provides a brine refining process for ammonia-soda enterprises without three wastes, and the purpose of zero emission of once magnesium-removing mud in brine refining is achieved.
In order to achieve the purpose, the technical scheme of the invention is a brine refining process of an ammonia-soda enterprise without three wastes, which adopts a concentrated seawater salt dissolving technology of waste discharge in a seawater desalination process, and crude brine obtained after salt is hydrated by concentrated seawater is sequentially added with lime, mirabilite and soda ash to refine the crude brine to obtain refined salt; in order to remove magnesium and part of calcium in the crude brine, lime milk and mirabilite are added, so that primary mud (namely primary magnesium removal mud) containing calcium sulfate (46.9% dry basis), calcium carbonate (8.2% dry basis) and magnesium hydroxide (27.8% dry basis) is formed, carbon dioxide is introduced to carry out a carbonization reaction, the carbonization reaction converts the primary mud into calcium carbonate precipitate and magnesium sulfate filtrate, and the calcium carbonate precipitate is transported to a calcium manufacturing workshop of soda ash company. The magnesium sulfate solution is purified to remove calcium ions in the magnesium sulfate solution, then the magnesium sulfate solution reacts with soda ash to prepare basic magnesium carbonate, high-purity magnesium oxide and other high-end magnesium products are prepared by taking the basic magnesium carbonate as a medium, and the filtrate is sodium sulfate solution and returns to a brine refining system to replace mirabilite.
Specifically, primary magnesium removal mud and secondary calcium removal mud are generated in the crude brine refining process, wherein the secondary calcium removal mud is used for preparing a calcium carbonate product, and the primary magnesium removal mud is treated through the following steps:
a: adding calcium sulfate, water or carbonized filtrate into the primary magnesium-removed mud, and pulping to obtain slurry;
b: introducing carbon dioxide into the slurry obtained in the step A for a carbonization reaction, then carrying out suction filtration on the slurry to obtain a calcium carbonate filter cake and a magnesium sulfate filtrate, and transporting the calcium carbonate filter cake to a calcium carbonate workshop of a soda company;
c: purifying the magnesium sulfate filtrate obtained in the step B, adding sodium carbonate to carry out a pyrolysis reaction, and carrying out suction filtration after the reaction is finished to obtain a basic magnesium carbonate filter cake and a sodium sulfate filtrate; carbon dioxide gas generated in the pyrolysis reaction returns to the carbonization reaction process to be used as raw material gas of carbon dioxide, and sodium sulfate filtrate returns to a brine refining system to replace mirabilite;
d: and D, washing and drying the basic magnesium carbonate filter cake obtained in the step C to obtain a basic magnesium carbonate product.
Further, the mass ratio of the magnesium hydroxide to the calcium sulfate in the primary magnesium removal mud in the step A is 1.7-1: 0.9; the solid-liquid ratio in the slurry is 1.
Further, the carbonation filtrate in the step A is the magnesium sulfate filtrate generated in the step B.
Further, the carbon dioxide source in the step B is lime kiln gas in the ammonia-soda process soda production, flue gas of a thermoelectric company or concentrated carbon dioxide gas after carbon capture; wherein the concentration of carbon dioxide in lime kiln gas in the ammonia-soda process soda ash production is 41 percent, and the concentration of carbon dioxide in flue gas from a thermoelectric company or concentrated carbon dioxide gas after carbon capture is respectively 13 percent and 40 percent to 100 percent.
Further, the flow rate of the carbon dioxide gas in the step B is 3L/min-400L/min, and the pressure is 0-6 kg.
And further, the retention time of the slurry in the carbonization reaction process in the step B is 0.5-2h.
Furthermore, the concentration of the magnesium sulfate in the magnesium sulfate filtrate in the step C is 0.2-1.5 mol/L.
Further, the method for purifying the magnesium sulfate filtrate in the step C comprises the following steps: adding sodium oxalate at normal temperature, wherein the ratio of sodium oxalate to calcium ions in magnesium sulfate filtrate is 1.2-1;
further, the method for purifying the magnesium sulfate filtrate in the step C comprises the following steps: heating the magnesium sulfate solution to 100 ℃, concentrating, cooling to 10-20 ℃, cooling and recrystallizing.
And furthermore, the reaction temperature of the magnesium sulfate filtrate in the step C is 50-95 ℃ when the magnesium sulfate filtrate reacts with sodium carbonate, and the reaction time is 1-2 h.
The refining process of the saline water of the ammonia-soda enterprise without three wastes has the beneficial effects that:
the refining process provided by the invention is based on the characteristics of an ammonia-soda production process, firstly proposes that sodium sulfate is used as a circulating medium, and a system is constructed in the ammonia-soda production process, so that the recycling of the brine refining primary magnesium removal mud and the integration of a carbon dioxide solidification system are realized, and the harmless value-added utilization of the thermoelectric flue gas carbon reduction and the brine refining primary magnesium removal mud is realized.
The refining process of the invention realizes zero emission of the magnesium removing mud of brine refining for one time, generates no new three wastes and realizes virtuous cycle.
The method for refining brine to remove carbon in the calcium and magnesium recovery process of the magnesium mud at one time ensures the recovery rate of calcium and magnesium, the purity of the product and high added value.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
FIG. 1 is a flow chart of the refining process of ammonia-soda enterprise brine without three wastes.
Detailed Description
The technical solution in the embodiments of the present invention is clearly and completely described below with reference to the drawings in the embodiments of the present invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
As shown in figure 1, the brine refining process of ammonia-soda enterprises without three wastes generation adopts a concentrated seawater salt-dissolving technology of waste discharge in a seawater desalination process, and crude brine obtained after the concentrated seawater is subjected to salt hydration is sequentially added with lime, mirabilite and soda ash to refine the crude brine to obtain refined salt; in order to remove magnesium and part of calcium in the crude brine, lime milk and mirabilite are added, so that primary mud (namely primary magnesium removal mud) containing calcium sulfate (46.9% dry basis), calcium carbonate (8.2% dry basis) and magnesium hydroxide (27.8% dry basis) is formed, carbon dioxide is introduced to carry out a carbonization reaction, the carbonization reaction converts the primary mud into calcium carbonate precipitate and magnesium sulfate filtrate, and the calcium carbonate precipitate is transported to a calcium manufacturing workshop of soda ash company. The magnesium sulfate solution is purified to remove calcium ions in the magnesium sulfate solution, then the magnesium sulfate solution reacts with soda ash to prepare basic magnesium carbonate, high-purity magnesium oxide and other high-end magnesium products are prepared by taking the basic magnesium carbonate as a medium, and the filtrate is sodium sulfate solution and returns to a brine refining system to replace mirabilite.
Specifically, primary magnesium removing mud and secondary calcium removing mud are generated in the refining process of the crude brine, wherein the secondary calcium removing mud is used for preparing a calcium carbonate product, and the primary magnesium removing mud is treated through the following steps:
a: adding calcium sulfate, water or carbonized filtrate into the primary magnesium-removed mud, and pulping to obtain slurry; preferably, the calcium sulfate is added in the following amount: the mass ratio of magnesium hydroxide to calcium sulfate in the primary magnesium removing mud is 1.7-1: 0.9; the solid-liquid ratio in the slurry is 1; the carbonized filtrate was the magnesium sulfate filtrate produced in step B.
B: introducing carbon dioxide into the slurry obtained in the step A for a carbonization reaction, then carrying out suction filtration on the slurry to obtain a calcium carbonate filter cake and a magnesium sulfate filtrate, and transporting the calcium carbonate filter cake to a calcium carbonate workshop of a soda company; preferably, the carbon dioxide source is lime kiln gas in the production of soda ash by an ammonia-soda process, flue gas of a thermoelectric company or concentrated carbon dioxide gas after carbon capture; wherein the concentration of carbon dioxide in lime kiln gas in the ammonia-soda process soda ash production is 41 percent, and the concentration of carbon dioxide in flue gas from a thermoelectric company or concentrated carbon dioxide gas after carbon capture is respectively 13 percent and 40 to 100 percent; further preferably, the flow rate of carbon dioxide gas is 3L/min-400L/min, the pressure is 0-6 kg, and the retention time of the slurry in the carbonization reaction process is 0.5-2h.
C: b, purifying the magnesium sulfate filtrate obtained in the step B, then adding sodium carbonate to carry out a pyrolysis reaction, and after the reaction is finished, carrying out suction filtration to obtain a basic magnesium carbonate filter cake and a sodium sulfate filtrate; carbon dioxide gas generated in the pyrolysis reaction returns to the carbonization reaction process to be used as raw material gas of carbon dioxide, and sodium sulfate filtrate returns to a brine refining system to replace mirabilite; preferably, the concentration of magnesium sulfate in the magnesium sulfate filtrate is 0.2-1.5 mol/L; the reaction temperature of the magnesium sulfate filtrate and the sodium carbonate is 50-95 ℃, and the reaction time is 1-2 h.
Preferably, the magnesium sulfate filtrate purification method comprises the following steps: adding sodium oxalate at normal temperature, wherein the ratio of the sodium oxalate to calcium ions in the magnesium sulfate filtrate is 1.2-1;
the magnesium sulfate filtrate purification method can also be as follows: heating the magnesium sulfate solution to 100 ℃, concentrating, cooling to 10-20 ℃, cooling and recrystallizing.
D: and D, washing and drying the basic magnesium carbonate filter cake obtained in the step C to obtain a basic magnesium carbonate product.
Example 1
A technology for refining salt water of ammonia-soda enterprises without three wastes (waste gas, waste water and waste residues) adopts a technology of discharging concentrated seawater for desalting salt in a seawater desalination process, lime, mirabilite and soda ash are sequentially added into crude salt water obtained after the concentrated seawater is subjected to salt hydration to refine the crude salt water to obtain refined salt, primary magnesium removing mud and secondary calcium removing mud are generated in the refining process, wherein the secondary calcium removing mud is used for preparing calcium carbonate products, and the primary magnesium removing mud is treated through the following steps:
adding 100g of primary magnesium removal mud with the weight ratio of magnesium hydroxide contained in the mud to the magnesium hydroxide material of 1: placing 7.3g of 0.8 beta calcium sulfate hemihydrate in a 500ml filter flask, adding 400ml of 0.3 mol/L magnesium sulfate carbide solution (recycling the magnesium sulfate solution obtained after the subsequent carbonization reaction) to prepare slurry, then placing the filter flask in a 50 ℃ constant temperature water bath kettle, and introducing kiln gas (CO) of a kiln No. 10 into the kettle by using an air pump 2 The content is 41 percent, the carbon dioxide in the lime kiln gas in the ammonia-soda process soda production is similar to the kiln gas source described below), the flow rate is 3L/min, and the carbonization time is 120min. After carbonization (the obtained calcium carbonate filter cake is transported to a calcium carbonate workshop of soda company), the content of the magnesium sulfate in the magnesium sulfate filtrate is 0.41mol/L, 200ml of the magnesium sulfate filtrate is taken out and put into a beaker, and the beaker is put into a 50 ℃ constant temperature water bath kettle. According to the weight percentage of magnesium sulfate: the molar ratio of sodium carbonate is 1:1.04 and 9g of sodium carbonate are added, and the reaction is stirred for 0.5h. And then heating the reacted mixture to the pyrolysis temperature of 85 ℃, and carrying out pyrolysis reaction for 1h (returning carbon dioxide obtained by the pyrolysis reaction to the carbonization reaction). After the reaction, the stirring was stopped and the mixture was aged at the pyrolysis temperature for 15min. Stopping heating, vacuum filtering the reacted mixture to obtain filtrate (mainly sodium sulfate solution, and optionally returning to salt water refining system to replace Natrii sulfas) and filter cake (basic magnesium carbonate filter cake washing and drying to obtain basic magnesium carbonate product), and analyzing the sodium sulfate filtrateThe content of each substance in the composition. By comparing the magnesium hydroxide content in the primary magnesium removal mud and the magnesium ion content in the magnesium sulfate filtrate and the sodium sulfate filtrate, the conversion rate of magnesium ions in carbonization reaction is calculated to reach more than 90%, and the conversion rate of magnesium ions in pyrolysis reaction is calculated to reach more than 93%.
Example 2
A technology for refining salt water of ammonia-soda enterprises without three wastes (waste gas, waste water and waste residues) adopts a technology of discharging concentrated seawater for desalting salt in a seawater desalination process, lime, mirabilite and soda ash are sequentially added into crude salt water obtained after the concentrated seawater is subjected to salt hydration to refine the crude salt water to obtain refined salt, primary magnesium removing mud and secondary calcium removing mud are generated in the refining process, wherein the secondary calcium removing mud is used for preparing calcium carbonate products, and the primary magnesium removing mud is treated through the following steps:
adding the magnesium hydroxide substances into 100g of primary magnesium removal mud according to the weight ratio of the magnesium hydroxide substances to the magnesium hydroxide substances contained in the primary magnesium removal mud of 1: 6.4g of 0.7 beta calcium sulfate hemihydrate is placed in a 500ml filter flask, 300ml of water is added to prepare slurry, then the filter flask is placed in a 50 ℃ constant temperature water bath kettle, and flue gas (CO) of a thermoelectric company is introduced by using an air pump 2 Content 13%) is 400L/min, carbonization 120min. After carbonization (the obtained calcium carbonate filter cake is transported to a calcium carbonate workshop of soda company), the content of the magnesium sulfate in the magnesium sulfate filtrate is 0.34mol/L, 200ml of the magnesium sulfate filtrate is taken out and put into a beaker, and the beaker is put into a 50 ℃ constant temperature water bath kettle. According to the weight percentage of magnesium sulfate: the molar ratio of sodium carbonate is 1:1.1 add 8g sodium carbonate, stir reaction for 0.5h. And then heating the reacted mixture to the pyrolysis temperature of 85 ℃, and carrying out pyrolysis reaction for 2 hours (the carbon dioxide obtained by the pyrolysis reaction is returned to be used in the carbonization reaction). After the reaction, the stirring was stopped and the mixture was aged at the pyrolysis temperature for 15min. Stopping heating, carrying out suction filtration on the reacted mixture to obtain a filtrate (the filtrate is mainly a sodium sulfate solution and can be returned to a brine refining system to replace mirabilite) and a filter cake (basic magnesium carbonate filter cake is washed and dried to obtain a basic magnesium carbonate product), and analyzing the content of each substance in the sodium sulfate filtrate. By comparing the magnesium hydroxide content in the primary magnesium removal mud and the magnesium ion content in the magnesium sulfate filtrate and the sodium sulfate filtrate, the conversion rate of magnesium ions in carbonization reaction is calculated to reach more than 70%, and the conversion rate of magnesium ions in pyrolysis reaction is calculated to reach more than 93%.
Example 3
A technology for refining saline water of ammonia-soda enterprises without three wastes (waste gas, waste water and waste residues) adopts a technology of discharging concentrated seawater to hydrate salt in a seawater desalination process, lime, mirabilite and soda ash are sequentially added into crude saline water obtained after the concentrated seawater is hydrated to refine the crude saline water to obtain refined salt, primary decalcified mud and secondary decalcified mud are generated in the refining process, wherein the secondary decalcified mud is used for preparing calcium carbonate products, and the primary decalcified mud is treated through the following steps:
adding 100g of primary magnesium removal mud with the weight ratio of magnesium hydroxide contained in the mud to the magnesium hydroxide material of 1:0.9 g of beta calcium sulfate hemihydrate 8.2g, 400ml of water was added to make a slurry, which was placed in a 2.5L pressure reactor, and flue gas (CO) from a thermoelectric company was introduced using an air pump 2 The content is 13 percent, the pressure at 50 ℃ is 3 kilograms, the flow is 50L/min, and the carbonization time is 120min. After carbonization (the obtained calcium carbonate filter cake is transported to a calcium carbonate workshop of soda company), the content of the magnesium sulfate in the magnesium sulfate filtrate is 0.38mol/L, 200ml of the magnesium sulfate filtrate is taken and put into a beaker, and the beaker is put into a 50 ℃ constant temperature water bath kettle. According to the weight percentage of magnesium sulfate: the molar ratio of sodium carbonate is 1:1.1 add 9g sodium carbonate, stir reaction for 0.5h. And then heating the reacted mixture to the pyrolysis temperature of 85 ℃, and carrying out pyrolysis reaction for 2 hours (the carbon dioxide obtained by the pyrolysis reaction is returned to be used in carbonization reaction). After the reaction, the stirring was stopped and the mixture was aged at the pyrolysis temperature for 15min. Stopping heating, carrying out suction filtration on the mixture after reaction to obtain a filtrate (the filtrate is mainly a sodium sulfate solution and can be returned to a brine refining system to replace mirabilite) and a filter cake (the basic magnesium carbonate filter cake is washed and dried to obtain a basic magnesium carbonate product), and analyzing the content of each substance in the sodium sulfate filtrate. By comparing the content of magnesium hydroxide in the primary magnesium removal mud and the content of magnesium ions in the magnesium sulfate filtrate and the sodium sulfate filtrate, the conversion rate of magnesium ions in carbonization reaction is calculated to be more than 80%, and the conversion rate of magnesium ions in pyrolysis reaction is calculated to be more than 93%.
Example 4
A technology for refining salt water of ammonia-soda enterprises without three wastes (waste gas, waste water and waste residues) adopts a technology of discharging concentrated seawater for desalting salt in a seawater desalination process, lime, mirabilite and soda ash are sequentially added into crude salt water obtained after the concentrated seawater is subjected to salt hydration to refine the crude salt water to obtain refined salt, primary magnesium removing mud and secondary calcium removing mud are generated in the refining process, wherein the secondary calcium removing mud is used for preparing calcium carbonate products, and the primary magnesium removing mud is treated through the following steps:
adding the magnesium hydroxide substances into 100g of primary magnesium removal mud according to the weight ratio of the magnesium hydroxide substances to the magnesium hydroxide substances contained in the primary magnesium removal mud of 1: placing 7.3g of 0.8 beta calcium sulfate hemihydrate in a 500ml filter flask, adding 400ml of water to obtain slurry, placing the filter flask in a 50 ℃ constant temperature water bath kettle, and introducing kiln gas (CO) of No. 9 kiln by using an air pump 2 Content 41%) is 400L/min, carbonization is 30min. After carbonization (the obtained calcium carbonate filter cake is transported to a calcium carbonate workshop of soda company), the content of magnesium sulfate in the magnesium sulfate filtrate is 0.25mol/L, 300ml of the magnesium sulfate filtrate is taken and placed into a beaker, 23ml of 0.25mol/L sodium oxalate solution is added, the mixture is stirred for 20min and aged for 20min, and the calcium ion concentration of the filtrate is filtered by suction filtration<0.16g/L. The filtrate was warmed to 50 ℃ in a water bath as magnesium sulfate: the molar ratio of sodium carbonate is 1:1.1, adding 8.8g of sodium carbonate, and stirring for reacting for 0.5h. And then heating the reacted mixture to the pyrolysis temperature of 85 ℃, and carrying out pyrolysis reaction for 1h (returning carbon dioxide obtained by the pyrolysis reaction to the carbonization reaction). After the reaction, the stirring was stopped and the mixture was aged at the pyrolysis temperature for 15min. Stopping heating, carrying out suction filtration on the reacted mixture to obtain a filtrate (the filtrate is mainly a sodium sulfate solution and can be returned to a brine refining system to replace mirabilite) and a filter cake (basic magnesium carbonate filter cake is washed and dried to obtain a basic magnesium carbonate product), and analyzing the content of each substance in the sodium sulfate filtrate. By comparing the magnesium hydroxide content in the primary magnesium removal mud and the magnesium ion content in the magnesium sulfate filtrate and the sodium sulfate filtrate, the conversion rate of magnesium ions in carbonization reaction is calculated to reach more than 90%, and the conversion rate of magnesium ions in pyrolysis reaction is calculated to reach more than 93%.
Example 5
A technology for refining salt water of ammonia-soda enterprises without three wastes (waste gas, waste water and waste residues) adopts a technology of discharging concentrated seawater for desalting salt in a seawater desalination process, lime, mirabilite and soda ash are sequentially added into crude salt water obtained after the concentrated seawater is subjected to salt hydration to refine the crude salt water to obtain refined salt, primary magnesium removing mud and secondary calcium removing mud are generated in the refining process, wherein the secondary calcium removing mud is used for preparing calcium carbonate products, and the primary magnesium removing mud is treated through the following steps:
adding hydrogen contained in the 100g of primary magnesium-removing mudThe ratio of the amount of magnesium oxide material is 1:0.9 g of beta calcium sulfate hemihydrate is put into a 500ml filter flask, 400ml of water is added to prepare slurry, then the filter flask is put into a 50 ℃ constant temperature water bath kettle, and kiln gas (CO) of a No. 9 kiln is introduced by an air pump (CO) 2 Content 41%) is 400L/min, carbonization is 30min. After carbonization (the obtained calcium carbonate filter cake is transported to a calcium carbonate workshop of soda company), the content of magnesium sulfate in the magnesium sulfate filtrate is 0.25mol/L, the temperature is raised to 100 ℃ for concentration, then the temperature is lowered to 10-20 ℃ for cooling recrystallization, and the saturated magnesium sulfate solution is washed. Dissolving crystalline magnesium sulfate heptahydrate in water to prepare a magnesium sulfate solution with the concentration of 0.35mol/L, putting 200ml of the magnesium sulfate solution into a 3-neck flask, heating the solution to 50 ℃ in a water bath, and adding the magnesium sulfate: the molar ratio of sodium carbonate is 1:1.1 add 8.2g sodium carbonate, stir for 0.5h. And then heating the reacted mixture to the pyrolysis temperature of 85 ℃, and carrying out pyrolysis reaction for 1h (returning carbon dioxide obtained by the pyrolysis reaction to the carbonization reaction). After the reaction is finished, the stirring is stopped, and the mixture is aged for 15min at the pyrolysis temperature. Stopping heating, carrying out suction filtration on the reacted mixture to obtain a filtrate (the filtrate is mainly a sodium sulfate solution and can be returned to a brine refining system to replace mirabilite) and a filter cake (basic magnesium carbonate filter cake is washed and dried to obtain a basic magnesium carbonate product), and analyzing the content of each substance in the sodium sulfate filtrate. By comparing the content of magnesium hydroxide in the primary magnesium removal mud and the content of magnesium ions in the magnesium sulfate filtrate and the sodium sulfate filtrate, the conversion rate of magnesium ions in carbonization reaction is calculated to reach more than 90%, and the conversion rate of magnesium ions in pyrolysis reaction is calculated to reach more than 93%.
It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Claims (10)
1. A three-waste-free ammonia-soda enterprise brine refining process adopts a concentrated seawater salt dissolving technology in a seawater desalination process, lime, mirabilite and soda ash are sequentially added into crude brine obtained after concentrated seawater salt hydration to refine the crude brine to obtain refined salt, primary magnesium removing mud and secondary calcium removing mud are generated in the refining process, wherein the secondary calcium removing mud is used for preparing calcium carbonate products, and the method is characterized in that the primary magnesium removing mud is treated by the following steps:
a: adding calcium sulfate, water or carbonized filtrate into the primary magnesium-removed mud for size mixing to obtain slurry;
b: introducing carbon dioxide into the slurry obtained in the step A for a carbonization reaction, then carrying out suction filtration on the slurry to obtain a calcium carbonate filter cake and a magnesium sulfate filtrate, and transporting the calcium carbonate filter cake to a calcium carbonate workshop of a soda company;
c: purifying the magnesium sulfate filtrate obtained in the step B, adding sodium carbonate to carry out a pyrolysis reaction, and carrying out suction filtration after the reaction is finished to obtain a basic magnesium carbonate filter cake and a sodium sulfate filtrate; carbon dioxide gas generated in the pyrolysis reaction returns to the carbonization reaction process to be used as raw material gas of carbon dioxide, and sodium sulfate filtrate returns to a brine refining system to replace mirabilite;
d: and D, washing and drying the basic magnesium carbonate filter cake obtained in the step C to obtain a basic magnesium carbonate product.
2. The process for refining ammonia-soda enterprise brine without three wastes according to claim 1, wherein the mass ratio of the magnesium hydroxide and the calcium sulfate in the primary magnesium removing mud in the step A is 1:0.9; the solid-liquid ratio in the slurry is 1.
3. The process of claim 1, wherein the carbonated filtrate in step a is the magnesium sulfate filtrate produced in step B.
4. The process for refining ammonia-soda enterprise brine without three wastes as claimed in claim 1, wherein in step B, the carbon dioxide source is lime kiln gas, flue gas of a thermoelectric company or concentrated carbon dioxide gas after carbon capture in ammonia-soda process soda production; wherein the concentration of carbon dioxide in lime kiln gas in the ammonia-soda process soda ash production is 41 percent, and the concentration of carbon dioxide in flue gas from a thermoelectric company or concentrated carbon dioxide gas after carbon capture is respectively 13 percent and 40 percent to 100 percent.
5. The process for refining ammonia-soda enterprise brine without three wastes as claimed in claim 1, wherein the flow rate of carbon dioxide gas in step B is 3L/min-400L/min, and the pressure is 0-6 kg.
6. The process for refining ammonia-soda enterprise brine without three wastes as claimed in claim 1, wherein the retention time of the slurry in the carbonization reaction process of step B is 0.5-2h.
7. The process according to claim 1, wherein the concentration of magnesium sulfate in the magnesium sulfate filtrate obtained in step C is 0.2mol/L to 1.5mol/L.
8. The process according to claim 1, wherein the purification method of the magnesium sulfate filtrate in step C comprises: adding sodium oxalate at normal temperature, wherein the ratio of sodium oxalate to calcium ions in the magnesium sulfate filtrate is 1.2-1.
9. The process according to claim 1, wherein the purification method of the magnesium sulfate filtrate in step C comprises: heating the magnesium sulfate solution to 100 ℃, concentrating, cooling to 10-20 ℃, cooling and recrystallizing.
10. The process according to claim 1, wherein the reaction temperature of the magnesium sulfate filtrate in step C with sodium carbonate is 50-95 ℃ and the reaction time is 1-2 hours.
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| CN109574055A (en) * | 2018-12-02 | 2019-04-05 | 河北科技大学 | A kind of method of salt slurry production precipitated calcium carbonate and epsom salt |
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| CN109574055A (en) * | 2018-12-02 | 2019-04-05 | 河北科技大学 | A kind of method of salt slurry production precipitated calcium carbonate and epsom salt |
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| Title |
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| 张文根: ""精制碱式碳酸镁新工艺"", 《新技术新工艺》, no. 3, pages 37 - 38 * |
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