Disclosure of Invention
Technical problem to be solved
Aiming at the technical problems in the prior art, the invention provides a hydrothermal method for preparing micro-nano CaSiO with controllable morphology3The method can realize the aim of adding the additive to CaSiO by changing the addition of the additive and the types and the addition amount of the additive3And (5) controlling the appearance.
(II) technical scheme
In order to achieve the purpose, the invention adopts the main technical scheme that:
preparation of CaSiO from waste silicon slag3The method comprises the following steps:
s1, grinding: drying, crushing and grinding the waste silicon slag to obtain ground silicon slag;
s2, mixing materials: uniformly mixing the ground silicon slag and sodium hydroxide to obtain a uniformly mixed material;
s3, roasting: roasting the uniformly mixed material to obtain a roasted material;
s4, dissolution filtration: adding water into the roasted material, stirring and dissolving out, and filtering to obtain a sodium silicate solution;
s5, purification: adjusting the pH value of the sodium silicate solution;
s6, calcining: crushing limestone and calcining to obtain active calcium oxide;
s7, emulsification: adding the active calcium oxide into water, stirring while adding, and filtering and screening insoluble impurity particles to obtain a calcium hydroxide emulsion;
s8, causticizing: adding the calcium hydroxide emulsion and the sodium silicate solution into a hydrothermal reaction kettle together according to a molar ratio, uniformly stirring to react, filtering after the reaction is finished, washing, and drying in an oven to obtain CaSiO3;
S9, crystallization: and S8, obtaining a mixed solution, evaporating, concentrating and crystallizing the mixed solution to obtain sodium hydroxide, returning to silicon extraction, and continuously recycling the obtained water.
Preferably, in the step S2, the amount of the sodium hydroxide is 1.0 to 1.6 times of the theoretical amount of the sodium hydroxide required for the silicon in the ground silicon slag to be completely reacted.
Preferably, in the step S3, the roasting temperature is 300 ℃ to 550 ℃, and the roasting constant temperature time is 50min to 250 min.
Preferably, in the step S4, the solid-liquid mass ratio of the roasted material to water is 1:2 to 1:10, the stirring temperature is 60 ℃ to 90 ℃, and the stirring time is 60min to 150 min.
Preferably, in step S5, hydrochloric acid is selected to adjust the pH of the sodium silicate solution, where the pH is 11 to 11.5.
Preferably, in the step S7, the concentration of the calcium hydroxide emulsion is 120 g.L-1~ 260g·L-1。
Preferably, in the step S8, the molar ratio is 0.9: 1-1.3: 1.
preferably, in step S8, 10% by weight of additives are simultaneously added to the hydrothermal reaction kettle.
Preferably, the additive is one of cetyltrimethylammonium bromide, sodium lauryl sulfate and sodium chloride.
Preferably, in the step S8, the temperature of the reaction in the hydrothermal reaction kettle is 180 ℃ to 240 ℃, the time of the reaction is 4h to 12h, the temperature of the drying in the oven is 90 ℃ to 120 ℃, and the time of the drying is 6h to 12 h.
(III) advantageous effects
The invention has the beneficial effects that:
1. the invention provides a method for preparing CaSiO by waste silicon slag3The method takes waste silicon slag as raw material, adopts hydrothermal synthesis technology and takes calcium hydroxide emulsion as precipitator to prepare CaSiO3The reaction condition is mild, the product is well crystallized, and the product appearance is controllable.
2. The invention provides a method for preparing CaSiO by waste silicon slag3The fibrous and acicular CaSiO prepared by the method3Good chemical stability, good high-temperature stability, good dielectric property and high added value of products, and has wide application in the fields of papermaking, high-grade ceramics, rubber, novel composite materials and the like.
3. The invention provides a method for preparing CaSiO by waste silicon slag3The method of (3) can recycle the sodium hydroxide produced in the process.
4. The invention provides a method for preparing CaSiO by waste silicon slag3The method provides a way for the resource and harmless utilization of the waste silicon slag in the metallurgical industry.
Detailed Description
For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.
The embodiment provides a method for preparing CaSiO from waste silicon slag3The method comprises the following steps:
s1, grinding: drying, crushing and grinding the waste silicon slag to obtain ground silicon slag;
s2, mixing materials: uniformly mixing the ground silicon slag and sodium hydroxide to obtain a uniformly mixed material;
s3, roasting: roasting the uniformly mixed material to obtain a roasted material;
s4, dissolution filtration: adding water into the roasted material, stirring and dissolving out, and filtering to obtain a sodium silicate solution;
s5, purification: adjusting the pH value of the sodium silicate solution;
s6, calcining: crushing limestone and calcining to obtain active calcium oxide;
s7, emulsification: adding the active calcium oxide into water, stirring while adding, and filtering and screening insoluble impurity particles to obtain a calcium hydroxide emulsion;
s8, causticizing: adding the calcium hydroxide emulsion and the sodium silicate solution into a hydrothermal reaction kettle together according to a molar ratio, uniformly stirring to react, filtering after the reaction is finished, washing, and drying in an oven to obtain CaSiO3;
S9, crystallization: and S8, obtaining a mixed solution, evaporating, concentrating and crystallizing the mixed solution to obtain sodium hydroxide, returning to silicon extraction, and continuously recycling the obtained water.
In step S1 of the present embodiment, the waste silicon slag is crushed and ground to 170-230 mesh, preferably, the waste silicon slag is ground to 200 mesh, and the obtained ground silicon slag can be better mixed with sodium hydroxide. Wherein the waste silicon slag contains a small amount of impurities such as aluminum, iron, calcium and the like.
In step S2 of the present embodiment, the amount of sodium hydroxide is 1.0 to 1.6 times the theoretical amount of sodium hydroxide required for the silicon in the ground silicon slag to react completely.
In step S3 of the present embodiment, the baking temperature is 300 to 550 ℃, the baking constant temperature time is 50 to 250min, and the chemical reactions as shown in formulas (1) and (2) occur during the baking process.
SiO2+2NaOH=Na2SiO3+H2O (1)
Na2SiO3+2NaOH=Na4SiO4+H2O (2)
In step S4 of the present embodiment, the solid-liquid mass ratio of the roasted material to water is 1:2 to 1:10, the stirring temperature is 60 to 90 ℃, and the stirring time is 60 to 150 min.
In step S5 of the present embodiment, hydrochloric acid is selected to adjust the pH of the sodium silicate solution to 11 to 11.5, since other acids are likely to precipitate with calcium ions. Since the sodium hydroxide is in excess during the alkali treatment of the silica residue, the hydrochloric acid added in this way can neutralize the excess sodium hydroxide on the one hand, and water and sodium chloride solution are formed. On the other hand, hydrochloric acid reacts with a small amount (about 3%) of sodium silicate solution to produce hydrated silica precipitate and sodium chloride solution, while sodium aluminate produced by the reaction of a small amount of aluminum and sodium hydroxide in step S3 reacts with hydrochloric acid to produce aluminum hydroxide and sodium chloride. A small amount of impurities (such as aluminum, iron, calcium and the like which are not completely precipitated) in the sodium silicate solution are removed by the precipitation adsorption of aluminum hydroxide and silicon dioxide, so that the quality of the product is improved. In particular to chemical reactions as shown in formulas (3) and (4).
Na2SiO3+2H++(n-1)H2O→2Na++SiO2·nH2O↓ (3)
NaAlO2+H++H2O→Na++Al(OH)3↓ (4)
In step S6 of the present embodiment, limestone is crushed to 2 to 5cm and then calcined in a muffle furnace.
In step S7 of the present embodiment, activated calcium oxide is cooled in a furnace, taken out, added to water while still hot, stirred to release heat, and filtered to remove insoluble foreign particles, thereby obtaining a calcium hydroxide emulsion having a concentration of 120g · L-1~260g·L-1In particular to a chemical reaction shown as a formula (5).
CaO+H2O→Ca(OH)2 (5)
In step S8 of the present embodiment, the calcium hydroxide emulsion and the sodium silicate solution are mixed at a molar ratio of 0.9: 1-1.3: 1, adding the mixture into a hydrothermal reaction kettle, adding 2-10 ml of additive with the mass percentage of 10%, and uniformly stirring to perform reaction. Wherein the additive can be any one of Cetyl Trimethyl Ammonium Bromide (CTAB), Sodium Dodecyl Sulfate (SDS) and sodium chloride (NaCl), and the temperature of the hydrothermal reaction is 180-240 ℃ for reactionThe time is 4-12 h. Filtering after the reaction is finished, washing, putting the product into an oven, and drying for 6 to 12 hours at the temperature of between 90 and 120 ℃ to obtain CaSiO3. The CaSiO can be prepared by changing the types and the addition amount of the additives3And (5) controlling the appearance. When the additive is CTAB, the prepared CaSiO3Is in a fibrous structure; when SDS is added as additive, CaSiO is obtained3The structure of the crystal whisker is formed; when the additive is NaCl or no additive is added, the prepared CaSiO3Has needle-shaped particle structure. In particular to a chemical reaction as shown in a formula (6).
Ca(OH)2+Na2SiO3=CaSiO3↓+2NaOH (6)
In step S9 of the present embodiment, a mixed solution of sodium hydroxide and sodium chloride is obtained in step S8, and sodium hydroxide is obtained by concentration and crystallization. Since the solubility of sodium chloride does not vary much with temperature, the solubility of sodium hydroxide is much greater than sodium chloride and varies greatly with temperature. In the process of concentration and crystallization, sodium chloride is crystallized out firstly, and sodium hydroxide is crystallized out later. And then, returning the crystallized sodium hydroxide to extract silicon.
The invention will now be further described with reference to the accompanying drawings and specific embodiments thereof:
example 1
Example 1 proposes a method for preparing CaSiO from waste silicon slag3The method comprises the following steps:
s1, grinding: the used waste silicon slag comprises the following components: SiO 22-65.68%,Fe2O3-6.64%, Al2O32.86 percent of minus, 3.02 percent of CaO, 2.43 percent of MgO and 0.08 percent of NiO, drying, crushing and grinding the waste silicon slag to 200 meshes to obtain ground silicon slag;
s2, mixing materials: uniformly mixing the ground silicon slag and sodium hydroxide, wherein the amount of the added sodium hydroxide is 1.2 times of the theoretical amount of the sodium hydroxide required by the silicon in the silicon slag to be just completely reacted, so as to obtain a uniformly mixed material;
s3, roasting: placing the uniformly mixed material in a muffle furnace, and roasting at the constant temperature of 550 ℃ for 120min to obtain a roasted material;
s4, dissolution filtration: adding water into the roasted material according to the solid-to-liquid ratio of 1:7, stirring and dissolving at the dissolving temperature of 80 ℃ for 90min, filtering after dissolving to obtain a sodium silicate solution and filter residues, and reserving the filter residues for later use;
s5, purification: adding hydrochloric acid into the sodium silicate solution, adjusting the pH value of the sodium silicate solution to 11, filtering to remove insoluble substances, and reserving the sodium silicate solution for later use;
s6, calcining: crushing limestone to 2-5 cm, placing the crushed limestone in a muffle furnace, and calcining the limestone for 2 hours at the temperature of 1150 ℃ to obtain activated calcium oxide;
s7, emulsification: cooling activated calcium oxide with furnace, taking out, adding into water while heating, stirring to release heat, filtering to remove insoluble impurity particles to obtain a solution with concentration of 180 g.L-1The calcium hydroxide emulsion of (1);
s8, causticizing: mixing the calcium hydroxide emulsion and the purified sodium silicate solution in a molar ratio of 1:1, adding the mixture into a hydrothermal reaction kettle, adding 5ml of CTAB solution with the mass percentage of 10%, uniformly stirring, reacting for 6 hours at the temperature of 220 ℃, filtering, washing, putting into an oven, and drying for 6 hours at the temperature of 90 ℃ to obtain CaSiO3;
S9, crystallization: and step S8, obtaining a mixed solution of sodium hydroxide and sodium chloride, evaporating, concentrating and crystallizing the mixed solution to obtain sodium hydroxide, returning to silicon extraction, and continuously recycling the obtained water.
As shown in FIG. 1, the CaSiO prepared by the method is3In a fibrous structure. CaSiO3The fiber as a novel inorganic filler has the characteristics of good chemical stability, good high-temperature stability and good dielectric property, has wide application in the fields of papermaking, high-grade ceramics, rubber, novel composite materials and the like, and compared with white carbon black, CaSiO3The fiber consumption and the added value are far higher than those of the white carbon black.
Example 2
Example 2 provides a method for preparing CaSiO from waste silicon slag3The method comprises the following steps:
s1, grinding: the used waste silicon slag comprises the following components: SiO 22-35.68%,Fe2O3-15.64%, Al2O32.86 percent of minus, 5.02 percent of CaO and 0.85 percent of ZnO, drying, crushing and grinding the waste silicon slag to 200 meshes to obtain ground silicon slag;
s2, mixing materials: uniformly mixing the ground silicon slag and sodium hydroxide, wherein the amount of the added sodium hydroxide is 1.4 times of the theoretical amount of the sodium hydroxide required by the silicon in the silicon slag to be just completely reacted, so as to obtain a uniformly mixed material;
s3, roasting: placing the uniformly mixed material in a muffle furnace, and roasting at the constant temperature of 550 ℃ for 150min to obtain a roasted material;
s4, dissolution filtration: adding water into the roasted material according to the solid-to-liquid ratio of 1:6, stirring and dissolving at the dissolving temperature of 80 ℃ for 100min, filtering after dissolving to obtain a sodium silicate solution and filter residues, and reserving the filter residues for later use;
s5, purification: adding hydrochloric acid into the sodium silicate solution, adjusting the pH value of the sodium silicate solution to 11.5, filtering to remove insoluble substances, and keeping the sodium silicate solution for later use;
s6, calcining: crushing limestone to 2-5 cm, placing the crushed limestone in a muffle furnace, and calcining the limestone for 2 hours at the temperature of 1150 ℃ to obtain activated calcium oxide;
s7, emulsification: cooling activated calcium oxide with furnace, taking out, adding into water while hot, stirring to release heat, filtering to remove insoluble impurity particles to obtain a solution with concentration of 220 g.L-1The calcium hydroxide emulsion of (1);
s8, causticizing: mixing the calcium hydroxide emulsion and the purified sodium silicate solution in a molar ratio of 1:1, adding the mixture into a hydrothermal reaction kettle, adding 5ml of SDS solution with the mass percentage content of 10%, uniformly stirring, reacting for 6 hours at the temperature of 220 ℃, filtering, washing, putting into an oven, and drying for 6 hours at the temperature of 100 ℃ to obtain CaSiO3;
S9, crystallization: and step S8, obtaining a mixed solution of sodium hydroxide and sodium chloride, evaporating, concentrating and crystallizing the mixed solution to obtain sodium hydroxide, returning to silicon extraction, and continuously recycling the obtained water.
As shown in FIG. 2, the CaSiO prepared by the method is3In a whisker structure. Comparison with example 1, different additive types, CaSiO3The aspect ratio of the fibers is different.
Example 3
Example 3 proposes a method for preparing CaSiO from waste silicon slag3The method comprises the following steps:
s1, grinding: the used waste silicon slag comprises the following components: SiO 22-85.46%,Fe2O3-2.67%, Al2O35.51 percent of waste silicon slag, 0.93 percent of CaO and 1.07 percent of ZnO, drying, crushing and grinding the waste silicon slag to 200 meshes to obtain ground silicon slag;
s2, mixing materials: uniformly mixing the ground silicon slag and sodium hydroxide, wherein the amount of the added sodium hydroxide is 1.0 time of the theoretical amount of the sodium hydroxide required by the silicon in the silicon slag to be just completely reacted, so as to obtain a uniformly mixed material;
s3, roasting: placing the uniformly mixed material in a muffle furnace, and roasting at the constant temperature of 550 ℃ for 120min to obtain a roasted material;
s4, dissolution filtration: adding water into the roasted material according to the solid-to-liquid ratio of 1:8, stirring and dissolving out at the dissolving-out temperature of 80 ℃ for 120min, filtering after dissolving out to obtain a sodium silicate solution and filter residues, and reserving the filter residues for later use;
s5, purification: adding hydrochloric acid into the sodium silicate solution, adjusting the pH value of the sodium silicate solution to 11.5, filtering to remove insoluble substances, and keeping the sodium silicate solution for later use;
s6, calcining: crushing limestone to 2-5 cm, placing the crushed limestone in a muffle furnace, and calcining the limestone for 2 hours at the temperature of 1150 ℃ to obtain activated calcium oxide;
s7, emulsification: cooling activated calcium oxide with furnace, taking out, adding into water while hot, stirring to release heat, filtering to remove insoluble impurity particles to obtain a solution with concentration of 140 g.L-1The calcium hydroxide emulsion of (1);
s8, causticizing: mixing the calcium hydroxide emulsion and the purified sodium silicate solution in a molar ratio of 1.05: 1, adding the components into a hydrothermal reaction kettle together, adding 5ml of NaCl solution with the mass percentage content of 10%, uniformly stirring, reacting at the temperature of 200 ℃ for 8 hours, filtering, washing, putting into an oven, and drying at the temperature of 120 ℃ for 8 hours to obtain CaSiO3;
S9, crystallization: and step S8, obtaining a mixed solution of sodium hydroxide and sodium chloride, evaporating, concentrating and crystallizing the mixed solution to obtain sodium hydroxide, returning to silicon extraction, and continuously recycling the obtained water.
As shown in FIG. 3, the CaSiO prepared by the above method3And has needle-shaped particle structure. Acicular CaSiO3Because of the characteristics of good chemical stability, good high-temperature stability and good dielectric property, the composite material has wide application in the fields of papermaking, high-grade ceramics, rubber, novel composite materials and the like, only one item of papermaking is needed, the annual demand can reach only 4000 ten thousand tons, and the price and the added value are high. The invention has obvious advantages and provides a way for the resource and harmless utilization of the waste silicon slag in the metallurgical industry.
Example 4
Example 4 provides a method for preparing CaSiO from waste silicon slag3The method comprises the following steps:
s1, grinding: the used waste silicon slag comprises the following components: SiO 22-71.64%,Fe2O3-9.84%, Al2O35.02 percent of minus 5.02 percent, 0.93 percent of CaO, 1.61 percent of MgO and 0.08 percent of NiO, drying, crushing and grinding the waste silicon slag to 200 meshes to obtain ground silicon slag;
s2, mixing materials: uniformly mixing the ground silicon slag and sodium hydroxide, wherein the amount of the added sodium hydroxide is 1.1 times of the theoretical amount of the sodium hydroxide required by the silicon in the silicon slag to be just completely reacted, so as to obtain a uniformly mixed material;
s3, roasting: placing the uniformly mixed material in a muffle furnace, and roasting at the constant temperature of 450 ℃ for 90min to obtain a roasted material;
s4, dissolution filtration: adding water into the roasted material according to the solid-to-liquid ratio of 1:5, stirring and dissolving out at the dissolving-out temperature of 80 ℃ for 90min, filtering after dissolving out to obtain a sodium silicate solution and filter residues, and reserving the filter residues for later use;
s5, purification: adding hydrochloric acid into the sodium silicate solution, adjusting the pH value of the sodium silicate solution to 11, filtering to remove insoluble substances, and reserving the sodium silicate solution for later use;
s6, calcining: crushing limestone to 2-5 cm, placing the crushed limestone in a muffle furnace, and calcining the limestone for 2 hours at the temperature of 1150 ℃ to obtain activated calcium oxide;
s7, emulsification: cooling activated calcium oxide with furnace, taking out, adding into water while hot, stirring to release heat, filtering to remove insoluble impurity particles to obtain a solution with concentration of 140 g.L-1The calcium hydroxide emulsion of (1);
s8, causticizing: mixing the calcium hydroxide emulsion and the purified sodium silicate solution in a molar ratio of 1.05: 1, adding the components into a hydrothermal reaction kettle together, stirring the components uniformly, reacting the mixture for 6 hours at the temperature of 220 ℃, filtering the mixture, washing the mixture, putting the washed mixture into an oven, and drying the washed mixture for 6 hours at the temperature of 90 ℃ to obtain CaSiO3;
S9, crystallization: and step S8, obtaining a mixed solution of sodium hydroxide and sodium chloride, evaporating, concentrating and crystallizing the mixed solution to obtain sodium hydroxide, returning to silicon extraction, and continuously recycling the obtained water.
CaSiO prepared by adopting the method3CaSiO obtained by mixing with sodium chloride solution as additive3The appearance is the same, and the product is in an acicular particle structure. The amount of sodium chloride obtained by reacting hydrochloric acid with an excess of sodium hydroxide is sufficient to obtain CaSiO3The morphology of (A) is a needle-like structure.
The method provided by the invention takes waste silicon slag as a raw material, adopts a hydrothermal synthesis technology, and takes calcium hydroxide emulsion as a precipitator to prepare CaSiO3. The CaSiO is realized by controlling the reaction temperature, the material ratio, the reaction time, the reactant concentration, whether the additive is added or not and the type and the addition amount of the additive3And (5) controlling the appearance.
Meanwhile, the waste silicon slag is from mineral acid leaching slag, ammonia leaching slag, sulfuric acid and ammonium bisulfate roasting leaching slag, such as zinc oxide ore, laterite nickel ore, fly ash, boron magnesium ore, copper oxide ore and the like, so that the green added value of the resources is improved.
The technical principles of the present invention have been described above in connection with specific embodiments, which are intended to explain the principles of the present invention and should not be construed as limiting the scope of the present invention in any way. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive efforts, which shall fall within the scope of the present invention.