2798 results about "Seed crystal" patented technology

Crystal growth systems with a baffle are provided. In one example, a crystal growth system for growing crystalline material, the crystalline material including silicon carbide, includes a seed holder configured to hold a silicon carbide seed crystal. The seed crystal provides a growth surface for growth of the silicon carbide crystalline material. The system includes a crucible at least partially defining a crystal growth chamber. The system includes a source material. The system includes one or more baffles within the crystal growth chamber and spaced apart from the source material. The one or more baffles include one or more apertures defined through the one or more baffles. The baffle includes a long dimension that is non-perpendicular to the growth surface of the seed crystal.

Disclosed in the present invention is a process for deeply removing fluorine from wastewater by means of an induced crystallization method in sludge backflow. The process comprises the following steps: step 1. placing lime powder and deionized water in a seed crystal reactor to prepare lime milk and at the same time putting a calcite seed crystal into the seed crystal reactor; step 2. introducing high-concentration fluorine-containing acidic wastewater into a reactor; and step 3. introducing the lime milk obtained in step 1 into the reactor in step 2 to undergo a reaction, wherein during the reaction, the pH value of the mixed solution is controlled to remain neutral. The present invention is based on a high-density sludge method (HDS process). By utilizing the HDS process, the advantages of effectively improving the sludge density, reducing the lime consumption, facilitating the operation, and enabling the water quality of an effluent to be more stable are realized. In conjunction with induced crystallization technology, an induced crystallization process in a high-density sludge backflow is formed to promote precipitation and crystallization and allow sedimentation to proceed quickly, thereby shortening the process time and overcoming the defects of traditional lime precipitation methods.

The invention relates to the technical field of concrete preparation, in particular to high-performance self-compacting concrete and a preparation method thereof, solves the defects in the prior art, and comprises the following components: cement, fly ash, slag powder, graphene oxide, nano-silica aerogel, a water reducer and an air entraining agent. Through silanization modification and magnetic field induction, the problem of interface incompatibility of GO and SA is solved. Graded mass transfer paths are formed between nano layers of GO and mesopores and macropores of SA. And the CaCO3 seed crystal in the SA hole directionally guides the oriented growth of the C-S-H gel, so that the early strength development rate is increased.

The invention discloses a stepped treatment process for multi-path recycling of oil and gas field drilling mud, which comprises the following steps: oxidizing and breaking gel of the drilling mud to scatter the mud structure, and then granulating and coagulating; then, carrying out the following gradient treatment: step 1, filtering the outlet water of granulation and coagulation, and taking the filtrate as reinjection water; step 2, carrying out nucleation granulation reaction on the filtrate obtained in the step 1, using effluent for preparing drilling fluid, and carrying out solid waste treatment on solid-phase crystal seeds and solid-phase mud cakes subjected to granulation and coagulation; and step 3, carrying out ozone flotation reaction on the effluent obtained in the step 2, wherein the effluent is used for preparing the guanidine gum fracturing fluid. According to the method, resource recycling of the waste drilling mud is achieved, the usage amount of a gel breaker in a traditional gel breaking and filter pressing technology is reduced, a filter pressing plate is omitted, the treatment efficiency in the mud recycling treatment process is improved, the treatment cost of the waste water-based drilling mud is reduced, different recycling ways can be met, and the method is suitable for popularization and application. And specific operation is flexible and changeable.

The preparation method comprises the following steps: obtaining a ZnO nano-particle seed crystal layer by a dip-coating-calcining method, and growing the ZnO nano-particle seed crystal layer on a porous ceramic membrane; inducing growth of ZnO nano-clusters on the surface of the ceramic membrane on which the ZnO nano-particles grow and in pore channels of the ceramic membrane through a hydrothermal reaction; and finally, soaking the ceramic membrane on which the ZnO nano-cluster grows in an n-octyltriethoxysilane-absolute ethyl alcohol solution, and carrying out silane chemical grafting treatment. A firm micro-nano composite multilevel structure is obtained on the surface and in pore channels of the ceramic membrane after modification through the method, meanwhile, the surface free energy of the surface and pore channels of the ceramic membrane is reduced through n-octyltriethoxysilane, the surface and the pore channels of the ceramic membrane have super-hydrophobic performance, and the preparation method is simple in preparation process, short in period and suitable for industrial production. And the universality is high.

The invention relates to the field of silicon carbide crystal growth, in particular to a high-efficiency silicon carbide single crystal growth method which comprises the following steps: (S.1) providing a reverse thermal field environment of which the temperature is sequentially reduced from top to bottom in the vertical direction; (S.2) heating the silicon carbide powder so as to generate silicon carbide sublimation gas; (S.3) the silicon carbide sublimation gas is introduced into the thermal field environment along with the carrier gas, so that the silicon carbide sublimation gas is layered under screening of the carrier gas, and a silicon-rich atmosphere located at the top of the thermal field environment and a supersaturated atmosphere located at the bottom of the thermal field environment are obtained; and (S.4) contacting the supersaturated atmosphere with a seed crystal arranged at the bottom of the thermal field environment so as to grow the silicon carbide single crystal on the surface of the seed crystal. Through the reverse thermal field design, carrier gas screening layering and carbon powder dynamic compensation mechanism, the problems that in traditional silicon carbide single crystal growth, silicon gas phase enrichment inhibits the crystallization rate, and defects are caused by unbalance of the stoichiometric ratio are systematically solved.

The invention relates to a czochralski method-based crystal growth interface shape detection method and device. The method comprises the steps that: a seed crystal temperature T and an interface electromotive force U at the same time in a crystal growth process are collected, and a T-U curve of the interface electromotive force U changing with the seed crystal temperature T is obtained; the change trend of the shape of a crystal growth interface in real time is judged by observing the deviation between the T-U curve and a reference line, wherein the reference line is a straight line passing through the starting point of the T-U curve, and the slope of the straight line is the Seebeck coefficient of the crystal. The invention also relates to a device used by the method. The detection method provided by the invention can detect the change trend of the shape of the crystal growth interface in real time in the crystal growth process, and can be applied to Czochralski method growth equipment for various single crystals such as lithium niobate, lithium tantalate, sapphire, yttrium aluminum garnet and the like.

To provide a high resistivity polycrystalline substrate, and a method for manufacturing the high resistivity polycrystalline substrate.SOLUTION: A method contains steps of: forming a polycrystalline substrate having a high resistibility (e.g., 1×10^5 or 1E+5 ohmic centimeter or more); forming a single crystal substrate by fusing a semiconductor grade silicon with a high grade, and thereafter, using a seed crystal, and starting a formation of the single crystal; bonding a second surface of the polycrystalline substrate when the polycrystalline substrate and the single crystal substrate are formed to a third surface of the single crystal substrate by using a surface active bonding (SAB) technique; and removing one part of the single crystal substrate.SELECTED DRAWING: Figure 4A

The invention relates to a single crystal diamond and a preparation method and application thereof. The preparation method comprises the following steps: performing etching treatment on a diamond seed crystal; then introducing a carbon source, hydrogen and chlorine, and carrying out deposition growth of the monocrystal diamond; after deposition growth is finished, post-treatment is conducted, and the single crystal diamond is obtained. Chlorine and hydrogen are introduced in the chemical vapor deposition process at the same time, selective growth of a diamond phase can be promoted, chlorine can help to reduce formation of non-diamond carbon (such as graphite), and therefore the quality and the growth speed of diamond single crystals are improved, and the dislocation density is reduced.

The invention provides a method for growing an oversized diamond polycrystalline film. The method comprises the following steps: S1, cleaning and drying a monocrystalline silicon wafer at room temperature; s2, carrying out pretreatment seed crystal on the monocrystalline silicon wafer, covering a diamond nanocrystalline layer on the silicon surface, and putting the monocrystalline silicon wafer into MPCVD (Microwave Plasma Chemical Vapor Deposition) equipment; s3, the cavity is vacuumized, then hydrogen is introduced for purging, and then vacuumizing is conducted again; then hydrogen is introduced, the air pressure is regulated and controlled to be 5-8 torr, and starting is started to ignite the plasma; s4, the microwave power is increased to 70 KW to 75 KW at the speed of 4.5 KW / min to 5.5 KW / min, the air pressure is increased to 165 torr to 180 torr at the speed of 10 torr / min to 30 torr / min, and the temperature is increased to 900 DEG C to 950 DEG C at the speed of 60 DEG C / min; s5, introducing growth gas, wherein the flow rate of hydrogen is 5000-6000 sccm, the flow rate of methane is 100-150 sccm, the flow rate of oxygen is 5-8 sccm, the flow rate of nitrogen is 1-2 sccm, and the flow rate of argon is 800-1000 sccm; and S6, after the growth is finished, cooling at a rate of 30 DEG C / min, and introducing nitrogen into the cavity for vacuum breaking until the temperature is reduced to room temperature, so as to obtain the oversized diamond polycrystalline film. The size of the oversized diamond polycrystalline film reaches 12 inches.

The invention discloses a recovery treatment process of heavy metal production wastewater, and relates to the technical field of wastewater treatment. Adjusting the pH value of the wastewater through pretreatment and stirring; 5%-10% of nanometer seed crystals are added in the seed crystal reinforced vulcanization process, a vulcanizing agent is controllably added, and large-particle-size precipitates are generated through pulse stirring; magnetic field separation is performed after magnetic microsphere adsorption; carrying out selective adsorption and acid regeneration on the chitosan-based magnetic resin; micro pollutants are removed through cooperation of the three-dimensional electrode and photocatalysis; concentrating 10-20 times by membrane distillation to enrich heavy metals; metal simple substances with the purity larger than or equal to 99.5% are recycled through pulse electrodeposition; and after deep treatment, the wastewater reaches the standard to be discharged or recycled (the recycling rate is greater than or equal to 70%). The process innovation comprises the steps of enhancing the seed crystal to improve the vulcanization efficiency by 30%, realizing rapid separation by a magnetic material, reducing the energy consumption by 40% by a three-dimensional electrode coupling membrane method, and constructing a vulcanizing agent regeneration (the regeneration rate is greater than or equal to 85%) and heavy metal closed-loop recovery system. Compared with a traditional process, the heavy metal removal rate is larger than or equal to 99.8%, the treatment cost of each ton of water is reduced by 25%-30%, and the method has the advantages of high efficiency, low consumption, environmental protection and recycling and is suitable for multi-metal complex wastewater.

The invention belongs to the technical field of single crystal growth equipment, and particularly relates to a seed crystal clamping assembly, in particular to a seed crystal pulling assembly, a silicon carbide single crystal growth device and a use method of the silicon carbide single crystal growth device. The seed crystal lifting assembly comprises a lifting rod and a lifting rod, a rotating head; wherein a cavity is formed in the wall body of the rotating head, and a groove is formed in the middle of the rotating head; and fan blades are fixedly arranged in the grooves. The fan blades are arranged in the rotating head, the unique airflow channel is designed, the lifting rod rotates to drive the fan blades to work, and forced airflow circulation is formed, so that the problem that the radial temperature difference of a crystal growth face is large is solved, back heat dissipation of seed crystals is remarkably improved, and the interface stability of crystal growth is improved. And meanwhile, the growth speed can be directly regulated and controlled in time by adjusting the rotating speed of the lifting rod, so that the growth efficiency and the crystal quality are synergistically improved.

The invention discloses a high-stability layered oxide sodium-ion battery positive electrode material and a preparation method thereof.The high-stability layered oxide sodium-ion battery positive electrode material comprises a layered oxide matrix and a surface coating layer, a sodium source, a nickel source, a manganese source, a lithium source and a magnesium source are mixed according to the stoichiometric ratio, a pre-sintered product is heated to 850-950 DEG C at the speed of 0.5-2 DEG C / min to be calcined, and the high-stability layered oxide sodium-ion battery positive electrode material is obtained. The calcined product, lithium phosphate and aluminum nitrate are subjected to ball milling and mixing in a citric acid solution with the pH value of 3-5 according to the mass ratio of 1: (0.005-0.03): (0.002-0.02), and the capacity retention ratio of the battery is larger than or equal to 88% after 500 times of circulation under the voltage range of 2.0-4.0 V and the multiplying power of 0.5 C. The comprehensive protection from the bulk phase to the interface is realized by triple doping and gradient coating, and the cycle life is prolonged by two times. Interlayer spacing expansion and coating layer ion conduction cooperate to reduce polarization, and the applicable temperature range is widened to-30 DEG C to 60 DEG C. Seed crystal induction and segmented sintering ensure batch consistency, and the method is suitable for large-scale production. Cheap Fe / Mn is adopted to replace part of Ni, and the material cost is reduced by 40% compared with similar products.

The invention relates to the technical field of silicon carbide single crystal growth, in particular to a high-purity semi-insulating silicon carbide single crystal for an optical element and a growth process thereof.The growth process includes the steps that S1, silicon carbide powder, a graphite crucible and the like are assembled to form a thermal field device, the thermal field device is placed in an induction furnace, room-temperature furnace washing treatment and low-temperature furnace washing treatment are sequentially carried out, and the silicon carbide powder is obtained; carrying out thermal field impurity removal treatment; s2, assembling the silicon carbide seed crystal and the impurity-removed thermal field device, raising the temperature in the induction furnace, conveying high-purity argon or mixed gas of high-purity argon and high-purity hydrogen into the induction furnace, and performing crystal growth; s3, after crystal growth is finished, high-temperature and high-pressure annealing treatment is carried out firstly, then furnace cooling treatment is carried out, and the high-purity semi-insulating silicon carbide crystal ingot for the optical element is obtained. The silicon carbide crystal ingot with excellent light transmission performance and high resistivity is obtained by selecting specific raw materials, reasonably designing an assembly mode and combining processes of thermal field impurity removal, high-temperature and high-pressure annealing and the like.

The invention provides a method for rapidly preparing an SSZ-13 molecular sieve membrane based on a double-template system, and belongs to the field of preparation and application of molecular sieve membrane materials. The polymer ammonium is introduced into the sol and seed crystal suspension, so that the nucleation and crystallization process in the synthesis system is obviously accelerated, the traditional synthesis time can be shortened by 50% or above, and the rapid growth of the SSZ-13 seed crystal on the surface of the porous carrier is realized. Based on the synergistic effect of the double template agents, the preparation repeatability of the SSZ-13 molecular sieve membrane is effectively improved, and large-scale application of high-quality membrane products is facilitated. The SSZ-13 molecular sieve membrane shows excellent separation performance in CO2 / CH4 mixed gas, and has remarkable industrial application value in the field of natural gas decarburization.

The utility model relates to the technical field of single crystal preparation by a liquid phase epitaxy method, in particular to a leading forced convection introducing device for single crystal growth by a resistance heating LPE method, which comprises a graphite crucible and a graphite heating component arranged on the outer side of the graphite crucible, one end of the graphite seed crystal rod extends into the graphite crucible and is connected with the graphite seed crystal support; the seed crystal is adhered to the bottom surface of the graphite seed crystal support; the graphite annular turbofan is arranged in the graphite crucible; the graphite annular turbofan is connected with the graphite seed rod through a jackscrew clamp; the other end of the graphite seed crystal rod is externally connected with a seed crystal lifting and rotating mechanism; and the graphite seed crystal rod drives the seed crystal and the graphite annular turbofan to do lifting and rotating motion. According to the device, the influence of adverse convection on the whole flow field is weakened, and the controllability of the whole flow field can be improved; and meanwhile, an ideal temperature field for growing high-quality silicon carbide crystals in the growth cavity is ensured.

The invention discloses a preparation method of a nano HZSM-5 molecular sieve, and belongs to the technical field of nano molecular sieve preparation, the preparation method comprises the following steps: 1, adding a silicon source, an aluminum source and a template agent into a supercritical crystallization reaction kettle, heating, stirring, and carrying out a melting reaction on the raw materials to obtain a seed crystal mixed material; introducing absolute ethyl alcohol into the seed crystal mixed material obtained by the melting reaction, heating, stirring, and carrying out crystallization reaction to obtain a reaction product; and cooling, washing, drying and roasting the obtained reaction product to obtain the nano HZSM-5 molecular sieve. According to the present invention, the melting reaction and the supercritical ethanol crystallization reaction technology are introduced into the preparation of the nanometer HZSM-5 molecular sieve for the first time, and the prepared nanometer HZSM-5 molecular sieve has advantages of small grain size, uniform distribution, large specific surface area and high yield.

The invention relates to the technical field of iron ore tailing resource utilization, in particular to a method for preparing iron oxide yellow by leaching iron ore tailings through an advanced oxidation technology, which comprises the following steps: adding a required amount of iron ore tailing powder into a persulfate solution, stirring to react, adding a reducing agent, boiling, filtering, adding alkali liquor to adjust the pH value, and filtering, thereby obtaining the iron oxide yellow. Pure liquid containing ferrous ions is obtained; taking part of the pure solution containing ferrous ions, and adding a potassium hydroxide solution to obtain an iron oxide yellow seed crystal solution; adding a pure solution containing ferrous ions into the iron oxide yellow seed crystal solution, adding an alkali solution to adjust the pH value, reacting, and separating and drying a product to obtain the iron oxide yellow. According to the method, the persulfate is adopted to leach iron from the iron ore tailings, and the iron oxide yellow is prepared from the leachate; harmless treatment of the iron ore tailings and value-added utilization of valuable resources are achieved, the raw material source of the iron oxide yellow industry is widened, and a wider prospect is provided for development of iron oxide yellow.

The invention provides an SSZ-13 molecular sieve as well as a preparation method and application thereof, the preparation method comprises the following steps: mixing activated silica-alumina minerals, SSZ-13 seed crystals, a silicon source, a template agent and a second alkali source to obtain dry glue, and then carrying out crystallization treatment on the dry glue in the presence of water vapor to obtain the SSZ-13 molecular sieve. According to the preparation method, a solvent is not adopted, a small amount of deionized water is used for providing a steam phase, the utilization rate of the raw materials can be increased, the high solid yield is obtained, the loss of a solid phase is reduced, no alkaline wastewater is generated, and the synthesis cost of the SSZ-13 molecular sieve is remarkably reduced. When the SSZ-13 molecular sieve prepared by the method is used for CO2 / CH4 adsorption separation, the SSZ-13 molecular sieve has relatively high separation selectivity.

The invention relates to the technical field of fertilizer processing, and provides a fluidized bed granulation device and a granulation method.The fluidized bed granulation device comprises a fluidized bed granulator, a cooler, a molten liquid conveying pump and a seed crystal making machine, and the molten liquid conveying pump is communicated with the fluidized bed granulator and the cooler through a first flow path; the molten liquid conveying pump is used for pumping molten liquid to the fluidized bed granulator and the cooler through the first flow path; the seed crystal making machine is respectively communicated with the fluidized bed granulator, the cooler and the molten liquid delivery pump through a second flow path, and is used for making the molten liquid pumped by the molten liquid delivery pump through the second flow path into seed crystals; and the seed crystal is conveyed to the fluidized bed granulator and the cooler through the second flow path. According to the invention, large-particle products with good roundness and good hardness can be produced without crushing of a crusher, and the product quality is improved.

According to the large-size single crystal diamond structure and the preparation method thereof, at least two diamond seed crystals are embedded into the grooves penetrating through the metal iridium film layer and the yttria-stabilized zirconia layer in the thickness direction, so that the single crystal diamond epitaxial layer can be grown on the diamond seed crystals through the homoepitaxy technology; meanwhile, the monocrystal diamond epitaxial layer is grown on the metal iridium body between the diamond seed crystals by utilizing a heteroepitaxy technology, so that the quality of the corresponding monocrystal diamond epitaxial layer between the diamond seed crystals can be improved; the problem that in the prior art, a splicing growth technology is adopted to obtain a large-size single crystal diamond epitaxial layer, steps or defects appear at splicing seams is solved, and therefore the large-size and high-quality single crystal diamond epitaxial layer can be obtained through the homoepitaxy and heteroepitaxy combined growth mode.

The invention discloses a softening treatment method for high-calcium and high-sulfate radical sewage. By adding the seed crystal, calcium sulfate is crystallized to achieve the purpose of removing calcium ions, so that the generation of chemical sludge is avoided, and the cost of treating the chemical sludge is further reduced; according to the invention, the seed crystal is selected according to the saturation degree of the sewage, and the dosage of the seed crystal is determined, so that the selection of the optimal seed crystal type and dosage is achieved, the cost is saved, and the purpose of softening water is achieved.

The present invention relates to the field of the preparation of silicon carbide crystals, and in particular to a device and method for the diameter expansion growth of a silicon carbide crystal. The device comprises a graphite diameter expansion device comprising a porous graphite diameter expansion ring. The porous graphite diameter expansion ring serves as a gas channel and is used for releasing an accumulated growth atmosphere during the diameter expansion growth of the silicon carbide crystal. The porous graphite diameter expansion ring not only ensures the smoothness of gas exhaust, but also solves the problem of polycrystalline silicon carbide growing on an edge of a silicon carbide seed crystal hindering the diameter expansion of the silicon carbide crystal. In addition, in the axial direction of the graphite diameter expansion device and in a direction away from the silicon carbide seed crystal, the porosity of the porous graphite diameter expansion ring gradually decreases, so that the growth atmosphere in a graphite crucible is controlled to ensure that the growth atmosphere can be discharged in time when the growth atmosphere is excessive in the early stage, and the discharge amount is reduced when the growth atmosphere in the later growth stage is insufficient, thus increasing the growth rate of the silicon carbide crystal. In addition, hard graphite felt is arranged around the diameter expansion device to serve as a heat insulation material, so that a rational temperature gradient of silicon carbide crystal growth is maintained.

The invention provides a microporous cathode electrochemical induced crystallization precipitation system and application thereof.The system comprises an anode chamber and a cathode chamber, an anode plate is a Ru / Ir mesh electrode, and a cathode plate is a stainless steel mesh cathode with the high mesh number of 100-300 meshs.According to the microporous cathode electrochemical induced crystallization precipitation system, the mesh cathode with the high mesh number is used for replacing a traditional anion exchange membrane; the high-mesh-number net-shaped cathode prevents hydrogen ions generated by the anode from migrating to the cathode chamber, the high-pH environment of the cathode chamber is guaranteed, the pH of the cathode chamber reaches up to 10.90, the phosphorus recovery efficiency reaches 93.14%, meanwhile, the cost is greatly reduced and is only 1.25% of that of an ion exchange membrane, needle-shaped nano-hydroxyapatite serves as an additional seed crystal, the needle-shaped nano-hydroxyapatite (ANHD) is put into the cathode chamber, and the yield of phosphorus is greatly increased. The seed crystal effect of ANHD is fully exerted, and the recovery efficiency of orthophosphorus is improved by 24.40%.

The invention relates to the technical field of molten salt, in particular to nitro binary molten salt and a preparation method thereof. The preparation method comprises the following steps: mixing sodium carbonate and a potassium hydroxide solution, and then adding a starch-based grafted crystal inhibitor to inhibit crystallization; adding a nitric acid aqueous solution in two stages, and introducing eutectic seed crystals to guide nucleation at the end of the first stage; crystal distribution is optimized through falling film evaporation and concentration and setting of partial reflux; and after spraying granulation, carrying out short-time melting reforming and controlled cooling in an inert atmosphere. According to the method, the composition uniformity and the structural stability of the molten salt are remarkably improved, so that the product has a melting point close to a theoretical eutectic point, low supercooling degree, high melting latent heat and excellent thermal cycling stability and corrosion resistance, and is suitable for an industrial heat storage system running for a long time.

The invention discloses a crystal growth device and a crystal growth method for gallium oxide crystal downward growth, and belongs to the technical field of gallium oxide single crystal preparation. The device comprises a crucible, an upper shaft, a heating mechanism and a heat preservation mechanism, the crucible is composed of a metal layer and an isolation layer arranged on the inner side wall of the metal layer, an opening is formed in the top of the metal layer, the thermal expansion coefficient of the side, away from the metal layer, of the isolation layer ranges from 0.5 * 10 <-6 > k <-1 > to 2.5 * 10 <-6 > k <-1 >, and the thermal expansion coefficient of the isolation layer is gradually increased outwards from the side, away from the metal layer, of the isolation layer. The rising rate is 2 * 10 <-6 >-3 * 10 <-6 > k <-1 > / mm; the upper shaft is arranged above an opening of the crucible and can lift and rotate relative to the crucible, a seed crystal support is arranged below the upper shaft, a first cooling pipeline is arranged in the upper shaft, and a second cooling pipeline is arranged in the seed crystal support. The crystal growth device breaks through the limitation of a traditional Czochralski method, a casting method and a Bridgman method, realizes downward growth of crystals, and can reduce the influence of crucible metal impurities on the crystals, so that gallium oxide single crystals with high quality, large size and high yield are obtained.

In a first step S101, the raw material is directly induction heated using a high-frequency induction heating coil (103) while cooling the outer periphery of a raw material (151) to or below the melting point of the raw material by a cooling mechanism (102) to form a raw material melt (152) (raw material melting step). In a second step S102, a seed crystal (161) is brought into contact with the melt (seeding step). In a third step S103, a crystal (153) is grown from the seed crystal (crystal growth step). In the third step S103, the high-frequency induction heating coil and the seed crystal are gradually separated from each other while maintaining the relative distance between the high-frequency induction heating coil and the outer periphery of the raw material, and the crystal is grown in the melt.

The invention relates to a method for separating sodium sulfate and sodium thiocyanate from a mixed waste salt solution, which comprises the following steps: carrying out catalytic oxidation, decoloration treatment and first solid-liquid separation on the mixed waste salt solution, and carrying out first evaporation concentration, first cooling crystallization and second solid-liquid separation on the obtained pretreated solution to obtain a sodium sulfate crude product and a filtrate, washing the sodium sulfate crude product, and carrying out third solid-liquid separation to obtain sodium sulfate; carrying out second evaporation concentration on the filtrate, adding sodium thiocyanate seed crystal, carrying out second cooling crystallization and fourth solid-liquid separation to obtain a sodium thiocyanate crude product and residual liquid, washing the sodium thiocyanate crude product, and carrying out fifth solid-liquid separation to obtain sodium thiocyanate; and circulating the washing waste liquid and the residual liquid to the pretreatment solution for mixing and recycling. According to the method, evaporation concentration is combined with cooling crystallization, sodium sulfate and sodium thiocyanate which are high in purity and extraction rate can be obtained through separation, and the whole preparation process is low in energy consumption and more environmentally friendly and integrally has good economic benefits.

The invention provides a gas phase transportation optimization device based on a PVT method. The device comprises a crucible, the interior of the crucible is used for containing raw materials to form a raw material area, seed crystals are arranged at the top of the crucible, and a heater is arranged on the periphery of the crucible; the at least one stage of conveying mechanism is arranged in the crucible, and the multiple stages of conveying mechanisms are arranged at intervals in the radial direction of the crucible; wherein each stage of conveying mechanism extends from the bottom of the crucible to the top of the crucible, a conveying channel is formed in each conveying mechanism, and the conveying channels are used for promoting gas-phase substances formed by sublimation of raw materials to be conveyed from the raw material area to the surface of the raw material area; and the extension terminal, close to the top of the crucible, of the conveying mechanism is located above the surface of the raw material area, so that the gas-phase substances are promoted to escape from the surface of the raw material area through the conveying channel. According to the device provided by the invention, the problems that gas-phase substances are difficult to transport in a raw material area in the single crystal growth process by a traditional PVT method, and meanwhile, the gas-phase substances are recrystallized on the surface of the raw material area, so that self-escape is hindered are solved.

The invention relates to the technical field of water treatment, and discloses a method for circularly inducing crystallization, hardness removal and desalination of calcium carbonate. Adding the seed crystal into high salt water; adding sodium hydroxide into the heavy salt water; adding sodium carbonate to generate a supersaturated solution; introducing the solution containing the calcium carbonate crystal nucleus into crystallization equipment; treating the reacted solution through solid-liquid separation equipment; further desalting the water body subjected to hardness removal by adopting a membrane separation mode; collecting and treating the formed calcium carbonate precipitate, and recovering the precipitate by adopting a separation technology; by adopting the synthesized vaterite type seed crystal, the hardness removal and desalination efficiency is remarkably improved in the cyclic induced crystallization process of calcium carbonate. Compared with the traditional non-synthetic seed crystal, the synthetic seed crystal has higher surface area and uniformity, so that the combination of calcium ions and carbonate ions can be more quickly induced to form a stable crystal nucleus, and the overall effect of the reaction is finally improved.