CN115672540A - Treatment method of ammonia-soda process alkaline residue - Google Patents
Treatment method of ammonia-soda process alkaline residue Download PDFInfo
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- CN115672540A CN115672540A CN202110822672.0A CN202110822672A CN115672540A CN 115672540 A CN115672540 A CN 115672540A CN 202110822672 A CN202110822672 A CN 202110822672A CN 115672540 A CN115672540 A CN 115672540A
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Abstract
The invention relates to a method for treating alkaline residue by an ammonia-soda process, belonging to the technical field of environmental protection and comprehensive utilization of solid waste. The method comprises three steps of conversion crystallization, flotation separation and evaporation salting-out; and (3) conversion and crystallization: reacting alkaline residue with sulfuric acid to generate calcium sulfate; flotation separation: calcium sulfate is separated from silicate impurities by a flotation method; evaporating for salting out or adjusting the pH value to reach the standard for discharging: the evaporation salting-out is to evaporate a salt-containing liquid phase, and sodium salt and magnesium salt are precipitated at different stages by controlling the evaporation amount. The invention completely decomposes the alkaline residue by a mineral separation technology, eliminates the environmental protection and safety problems of the alkaline residue, and simultaneously obtains products with high added values such as calcium sulfate, sodium chloride, magnesium chloride and the like. And considerable economic benefits are generated. Provides a new method for treating caustic sludge.
Description
Technical Field
The invention belongs to the technical field of environmental protection and comprehensive utilization of solid waste, and particularly relates to a method for comprehensively utilizing waste residues in ammonia-soda process soda ash production.
Background
The alkaline residue is CaCO 3 、CaSO 4 、CaCl 2 、Mg(OH) 2 Waste residue containing calcium salt and magnesium salt as main components, and SiO 2 And the like silicate components. The alkaline residue solution is alkaline and has a pH value of about 10. The fine granularity of the caustic sludge causes the specific surface area of the caustic sludge to be large, the water content to be large, and the caustic sludge is difficult to store and treat.
At present, no economical and effective alkali residue treatment method exists in the world, and most of the known technologies adopt that waste liquid is conveyed to a residue field, and alkali residue is naturally settled and then is accumulated and stored for treatment. As the solid particles of the alkaline residue are extremely small and the average particle size is 10 mu m, the alkaline residue is determined to naturally settle until the water content is 80 percent, and then the alkaline residue does not continue to settle. Therefore, the treatment mode occupies a large amount of land, and huge potential safety and environmental protection hazards are generated along with the increase of the stacking height of the slag yard.
In order to solve the problem of caustic sludge, various methods for comprehensively utilizing and treating caustic sludge are disclosed in the prior art. For example, patent publication No. CN140151A discloses a method for preparing engineering soil by using alkaline residue; the patent with publication number CN102092972A discloses a method for synthesizing cement clinker, auxiliary materials and cement by using soda ash waste residue and ammonia distillation waste liquid; patent publication No. CN103664242A discloses a method of preparing a potash fertilizer using alkali slag; patent publication No. CN107555462A discloses the preparation of precipitated barium sulfate, light calcium carbonate, agricultural ammonium chloride or industrial crude salt sodium chloride by comprehensive utilization and recovery of caustic sludge. Patent publication No. CN108483461A discloses a method for recycling caustic sludge in soda production, so that the caustic sludge generated in the soda production process is significantly reduced.
The basic idea of the method is that (1) the caustic sludge is stacked and buried after harmless treatment, and the method continuously accumulates along with the production, so that great influence is finally generated on environment and safety; (2) the method can not completely treat the alkaline residue, and even other components are introduced to make the rest part of the alkaline residue more difficult to treat; (3) chemical treatment into a specific product, but is limited to single use and small amount, and is difficult to scale up.
Disclosure of Invention
The invention aims to solve the technical problem of the prior art and provides a method for treating waste residues generated in the production of soda ash by an ammonia-soda process.
The technical problem to be solved by the present invention is achieved by the following technical means. The invention relates to a method for treating alkaline residue by an ammonia-soda process, which comprises three steps of conversion crystallization, flotation separation and evaporation salting-out;
and (3) conversion and crystallization: reacting alkaline residue with sulfuric acid to generate calcium sulfate;
flotation separation: calcium sulfate is separated from silicate impurities by a flotation method;
evaporating for salting out or adjusting the pH value to reach the standard for discharging:
the evaporation salting-out is to evaporate a salt-containing liquid phase, and sodium salt and magnesium salt are separated out at different stages by controlling the evaporation amount;
and the step of adjusting the pH value to reach the standard and discharging is to adjust the pH value of the liquid phase obtained by flotation separation to reach the standard and discharge.
The invention relates to a method for treating alkaline residue by an ammonia-soda process, which has the preferable technical scheme that when the alkaline residue is transformed and crystallized: the reaction temperature is 10 to 40 ℃, the reaction time is 2 to 6 hours, and the pH value of a liquid phase in the reactor is 1.0 to 6.0.
The invention relates to a method for treating alkaline residue by an ammonia-soda process.
The invention relates to a method for treating alkaline residue by an ammonia-soda process, which has the preferable technical scheme that the method comprises the following steps:
(1) and (3) conversion and crystallization: the alkaline residue enters an ore mill to be ground until the particle size is smaller than 100 meshes, and if the particle size of the alkaline residue is uniform and the particle size is smaller than 100 meshes, the operation is omitted; feeding the ground slurry into a reaction crystallizer, and adding sulfuric acid to control the pH value of a liquid phase in the reaction crystallizer to be between 1.0 and 6.0;
(2) flotation separation: discharging the slurry from the reaction crystallizer, feeding the slurry into a stirring barrel, feeding a flotation regulator into the stirring barrel, feeding a flotation collector into the stirring barrel, mixing the slurry for 1 to 20 minutes, feeding the slurry into a flotation machine for flotation, wherein a foam product is a calcium sulfate product, and a product in a tank is silicate tailings; filtering and dehydrating the foam product, wherein the solid phase is a calcium sulfate product, and the liquid phase enters an evaporation salting-out section; filtering and dehydrating the product in the tank, wherein the solid phase is silicate tailings, and the liquid phase enters an evaporation salting-out section;
(3) evaporation salting-out: collecting the liquid phase of the flotation separation section to a collecting tank, evaporating a certain amount of water, then beginning to separate out sodium chloride, continuing to evaporate until magnesium salts are separated out, and carrying out solid-liquid separation to obtain a sodium chloride product; further evaporating the liquid phase, and precipitating magnesium salt until old brine is obtained or evaporating to dryness; to obtain magnesium chloride product, magnesium sulfate product or the mixture of the magnesium chloride product and the magnesium sulfate product.
The further preferable technical scheme comprises the following steps:
(1) and (3) conversion and crystallization: wet grinding, wherein the discharge concentration is 10 to 40 percent, the flow rate is controlled to enter a reactor, sulfuric acid is 10 to 50 percent and enters the reactor, the use amount is 80 to 100 percent of alkaline residue, the retention time of materials in the reactor is controlled to be 2 to 8 hours, the reaction temperature is 10 to 40 ℃, and the pH value of slurry in a crystallizer is 1.0 to 6.0;
(2) flotation separation: slurry of the reactor enters a stirring barrel for size mixing, a flotation regulator enters the stirring barrel for size mixing, a flotation collector enters the stirring barrel for size mixing, the size mixing is carried out for 1 to 20 minutes, the slurry enters a flotation machine for primary roughing and is carefully selected for 1 to 4 times, a foam product is calcium sulfate dihydrate, a product in a tank is silicate tailings, and the dihydrate gypsum, the tailings and a salt-containing liquid phase (the dihydrate gypsum grade is not lower than 95%) are obtained after solid-liquid separation;
(3) evaporation salting-out: and (3) allowing the salt-containing liquid phase to enter an evaporation pool, precipitating a magnesium sulfate product when the concentration of the liquid phase is 15 to 30%, continuously evaporating to obtain old brine, and evaporating to obtain a magnesium chloride product, a magnesium sulfate product or a mixture of the magnesium chloride product and the magnesium sulfate product.
Compared with the prior art, the invention has the following beneficial effects:
the invention completely decomposes the caustic sludge by a mineral separation method, eliminates the potential environmental safety hazard of the caustic sludge, and simultaneously obtains a calcium sulfate product, a sodium chloride product, a magnesium chloride product and a small amount of silicate tailings. Calcium sulfate, sodium chloride and magnesium chloride are products with higher added values, and silicate tailings have no potential environment and safety hazards and can be used as raw materials of the building industry, such as cement and the like.
The method controls the granularity of the calcium sulfate crystal through the reaction of the alkaline residue and the sulfuric acid, and solves the problem that the granularity is too fine and is difficult to dehydrate; the problem of separation of calcium sulfate and silicate impurities is solved by a flotation method; the stage separation of water-soluble salts is realized by controlling the amount of evaporated water, and the problem of separation of soluble salts such as sodium chloride, magnesium chloride and magnesium sulfate is solved.
The invention treats the alkaline residue, adopts the mineral separation technology, completely decomposes the alkaline residue, meets the requirements of environmental protection and safety, and simultaneously generates considerable economic benefits. Meets the requirement of environmental protection and safety, obtains products with high added value, and provides a new method for treating the caustic sludge.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The following further describes specific embodiments of the present invention in order to facilitate further understanding of the present invention by those skilled in the art, and does not constitute a limitation to the claims thereof.
Example 1, referring to fig. 1, a method for treating ammonia-soda process caustic sludge:
the caustic sludge mainly comprises the following components: 60% of calcium carbonate, 10% of dihydrate gypsum, 10% of magnesium hydroxide and 10% of acid insoluble substance, and the treatment method comprises the following steps:
(1) a conversion crystallization section, wet grinding, controlling the discharge concentration to be 25%, controlling the flow rate to enter a reactor, controlling the sulfuric acid to enter the reactor at the concentration of 10%, controlling the retention time of materials in the reactor to be 3 hours, controlling the reaction temperature to be 25 ℃, and controlling the pH value of slurry in a crystallizer to be 3.5, wherein the usage amount of the sulfuric acid is 85% of the amount of alkaline residue;
(2) and in the flotation separation section, slurry of the reactor enters a stirring barrel for size mixing, a flotation regulator enters the stirring barrel for size mixing, a flotation collector enters the stirring barrel for size mixing and is subjected to size mixing for 2 minutes, the slurry enters a flotation machine for primary roughing and 2 times of fine selection, a foam product is calcium sulfate dihydrate, a product in a tank is silicate tailings, dihydrate gypsum, tailings and a salt-containing liquid phase are obtained after solid-liquid separation, the content of the dihydrate gypsum in the concentrate is not lower than 95%, the yield is 105%, and the yield of the tailings is 15%.
(3) Evaporating the salt precipitation section, allowing the salt-containing liquid phase to enter an evaporation tank, separating out magnesium sulfate product when the concentration of the liquid phase reaches 25%, continuously evaporating to obtain old brine, evaporating to obtain crude magnesium sulfate product containing epsomite (MgSO) (MgSO) as main ingredient 4 .7H 2 O), yield 70%.
Example 2, referring to fig. 1, a method for treating ammonia-soda process caustic sludge:
the caustic sludge mainly comprises the following components: caCO 3 45%，Mg(OH) 2 10%，CaO 6%，CaSO 4 6%，CaCl 2 10 percent, naCl l5 percent, acid insoluble substance 12 percent,
(1) a conversion crystallization section, wet grinding, controlling the discharge concentration to be 25%, controlling the flow rate to enter a reactor, controlling the sulfuric acid to enter the reactor at the concentration of 15%, wherein the use amount is 85% of the alkali residue amount, controlling the retention time of the materials in the reactor to be 3 hours, the reaction temperature to be 25 ℃, and the pH value of slurry in a crystallizer to be 3.5;
(2) in the flotation separation section, slurry in a reactor enters a stirring barrel for size mixing, a flotation regulator enters the stirring barrel for size mixing, a flotation collector enters the stirring barrel for size mixing, the size mixing is carried out for 3 minutes, the slurry enters a flotation machine for primary roughing and 2 times of fine selection, a foam product is concentrate, the main component is calcium sulfate dihydrate, a product in a tank is tailing, the main component is silicate, dihydrate gypsum, tailing and a salt-containing liquid phase are obtained after solid-liquid separation, the grade of the dihydrate gypsum of the concentrate is not lower than 95%, the yield is 110%, and the yield of the tailing is 18%;
(3) evaporating the salt-separating section, allowing the salt-containing liquid phase to enter an evaporation tank, separating out sodium chloride product with a yield of 20% when the concentration of the liquid phase is 15%, continuously evaporating until the concentration of the liquid phase is 20%, separating out magnesium chloride product, continuously evaporating to obtain old brine, evaporating to obtain crude magnesium chloride product, wherein the main components of the magnesium chloride product are bischofite and epsomite (MgCl) 2 .6H 2 O and MgSO 4 .7H 2 O), yield 60%.
Example 3, referring to fig. 1, a method for treating ammonia-soda process caustic sludge:
the caustic sludge mainly comprises the following components: caCO 3 45%，Mg(OH) 2 10%，CaO 6%，CaSO 4 6%，CaCl 2 10 percent, naCl l5 percent, acid insoluble substance 12 percent,
(1) a conversion crystallization section, wet grinding, discharging concentration of 10%, controlling flow to enter a reactor, controlling sulfuric acid to enter the reactor at concentration of 15%, wherein the consumption is 85% of caustic sludge, controlling the retention time of materials in the reactor for 3 hours, the reaction temperature is 25 ℃, and the pH value of slurry in a crystallizer is 3.5;
(2) a flotation separation section, wherein slurry of the reactor enters a stirring barrel for size mixing, a flotation regulator enters the stirring barrel for size mixing, a flotation collector enters the stirring barrel for size mixing, the size mixing is carried out for 3 minutes, the slurry enters a flotation machine for primary roughing and 2 times of fine separation, a foam product is concentrate, the main component is calcium sulfate dihydrate, a product in a tank is tailing, the main component is silicate, the dihydrate gypsum, the tailing and a liquid phase containing salt are obtained after solid-liquid separation, the grade of the dihydrate gypsum of the concentrate is not lower than 95%, the yield is 110%, and the yield of the tailing is 18%;
(3) the concentration of the liquid phase containing salt is 3%, sodium carbonate is added, the pH value is adjusted to be 6.0 to 8.0, the content of each ion in water meets the national environmental protection requirement, and the salt can be directly discharged.
Claims (5)
1. A method for treating alkaline residue by an ammonia-soda process is characterized by comprising the following steps: the method comprises three steps of conversion crystallization, flotation separation and evaporation salting-out;
and (3) conversion and crystallization: reacting alkaline residue with sulfuric acid to generate calcium sulfate;
flotation separation: calcium sulfate is separated from silicate impurities by a flotation method;
evaporating for salting out or adjusting the pH value to reach the standard for discharging:
the evaporation salting-out is to evaporate a salt-containing liquid phase, and sodium salt and magnesium salt are separated out at different stages by controlling the evaporation amount;
and the discharge after the pH value is adjusted to reach the standard is that when the concentration of the salt-containing liquid phase is lower than 5%, the liquid phase obtained by flotation separation is discharged after the pH value is adjusted to reach the standard.
2. The method for treating the alkaline residue in the ammonia-soda process according to claim 1, wherein during the conversion and crystallization: the reaction temperature is 10 to 40 ℃, the reaction time is 2 to 6 hours, and the pH value of a liquid phase in the reactor is 1.0 to 6.0.
3. The method for treating the alkaline residue produced in the ammonia-soda process according to claim 1, wherein the flotation separation adopts a direct flotation process, and calcium sulfate is enriched in the foam product.
4. The method for treating the alkaline residue of the ammonia-soda process according to claim 1, which is characterized by comprising the following steps of:
(1) and (3) conversion and crystallization: the alkaline residue enters an ore mill to be ground until the particle size is smaller than 100 meshes, and if the particle size of the alkaline residue is uniform and the particle size is smaller than 100 meshes, the operation is omitted; feeding the ground slurry into a reaction crystallizer, and adding sulfuric acid to control the pH value of a liquid phase in the reaction crystallizer to be between 1.0 and 6.0;
(2) flotation separation: discharging the slurry from the reaction crystallizer, feeding the slurry into a stirring barrel, feeding a flotation regulator into the stirring barrel, feeding a flotation collector into the stirring barrel, mixing the slurry for 1 to 20 minutes, feeding the slurry into a flotation machine for flotation, wherein a foam product is a calcium sulfate product, and a product in a tank is silicate tailings; filtering and dehydrating the foam product, wherein the solid phase is a calcium sulfate product, and the liquid phase enters an evaporation salting-out section; filtering and dehydrating the product in the tank, wherein the solid phase is silicate tailings, and the liquid phase enters an evaporation salting-out section;
(3) evaporation salting-out: collecting the liquid phase of the flotation separation section to a collecting tank, evaporating a certain amount of water, then beginning to separate out sodium chloride, continuing to evaporate until magnesium salts are separated out, and carrying out solid-liquid separation to obtain a sodium chloride product; further evaporating the liquid phase, and precipitating magnesium salt until old brine is obtained or evaporating to dryness; to obtain magnesium chloride product, magnesium sulfate product or the mixture of the magnesium chloride product and the magnesium sulfate product.
5. The method for treating the alkaline residue of the ammonia-soda process according to claim 4, comprising the following specific steps:
(1) and (3) conversion and crystallization: wet grinding, wherein the discharging concentration is 10-40%, the flow is controlled to enter a reactor, sulfuric acid with the concentration of 10-50% enters the reactor, the using amount is 80-100% of alkaline residue, the retention time of materials in the reactor is controlled to be 2-8 hours, the reaction temperature is 10-40 ℃, and the pH value of slurry in a crystallizer is 1.0-6.0;
(2) flotation separation: slurry of the reactor enters a stirring barrel for size mixing, a flotation regulator enters the stirring barrel for size mixing, a flotation collector enters the stirring barrel for size mixing, the size mixing is carried out for 1 to 20 minutes, the slurry enters a flotation machine for one-time roughing and 1 to 4 times of fine selection, a foam product is calcium sulfate dihydrate, a product in a tank is silicate tailings, and the dihydrate gypsum, the tailings and a salt-containing liquid phase are obtained after solid-liquid separation;
(3) evaporation salting-out: and (3) allowing the salt-containing liquid phase to enter an evaporation pool, separating out a product when the concentration of the liquid phase is 15 to 30%, continuously evaporating to obtain old brine, and evaporating to obtain a magnesium chloride product, a magnesium sulfate product or a mixture of the magnesium chloride product and the magnesium sulfate product.
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