40 results about "Crystal size distribution" patented technology

A solid hollow fiber cooling crystallizer and method for crystallizing aqueous and organic solutions are provided. The solid hollow fiber crystallizer (SHFC) for carrying out cooling crystallization of inorganic / organic microsolutes / macrosolutes from solution generally includes a bundle of non-porous hollow fibers mounted within a shell where a feed solution for crystallization flows through the lumen side of the hollow fibers and a cooling solution flows through the shell side to form nuclei and subsequently crystals in the feed solution at a temperature below its saturation temperature. The solid hollow fiber crystallizer may be combined with a mixing device, such as a completely stirred tank or static mixer, to further effectuate crystallization. The solid hollow fiber crystallizer may be operated in a number of modes including feed recycle mode, once through mode, SHFC-in-line static mixer in series mode, and SHFC-CST in series mode. The advantages of solid hollow fiber cooling crystallization in comparison to conventional crystallization processes include improved temperature control between crystallizing solution and coolant, higher nucleation rates, improved control of crystal size and crystal size distribution, smaller crystal size, capability for decoupling crystal nucleation and crystal growth, decreased fouling of process equipment, and improved process scale-up.

In a method of synthesizing a silicoaluminophosphate molecular sieve having 90%+CHA framework type character, a reaction mixture is prepared comprising first combining a reactive source of aluminum with a reactive source of phosphorus to form a primary mixture that is aged. A reactive source of silicon and a template for directing the formation of the molecular sieve can then be added to form a synthesis mixture. Crystallization is then induced in the synthesis mixture. Advantageously, (i) the source of silicon comprises an organosilicate, (ii) the source of phosphorus optionally comprises an organophosphate, and (iii) the crystallized silicoaluminophosphate molecular sieve has a crystal size distribution such that its average crystal size is not greater than 5 μm. The molecular sieve can then preferably be used in a hydrocarbon (oxygenates-to-olefins) conversion process.

The preparation process of magnesium hydroxide for fire retardant belongs to the field of chemical material technology. The preparation process includes the steps of: mixing the main material light burnt magnesia and water in the weight ratio of 0.5-3 to 3-7, dropping sodium hydroxide aqua while stirring to ultimate sodium hydroxide concentration in the system of 4-6 M, stirring for 10-60 min before transferring to a high pressure reactor to a filling degree of 70-80 %, hydrothermal reaction at 140-180 for 6-10 hr, cooling the product naturally, water washing and stoving to obtain the flake magnesium hydroxide for fire retardant. The preparation process has the advantages of simplicity and low cost, and the prepared magnesium hydroxide product has excellent crystallization, regular shape and homogeneous crystal size distribution and is suitable for use in fire retardant.

The invention relates to a method for preparing psicose crystals. The present invention adopts the combination of evaporation crystallization method and cooling crystallization method to prepare allulose crystals, the preparation process is simple, easy to operate, and the crystallization period is short. In the present invention, during the evaporation crystallization process, the seed crystals are added at a lower solid content (70-75%), which is beneficial to the crystallization process, and the crystal growth rate in all directions is more uniform, which can shorten the entire crystallization period and save energy. Consumption; crystallization is carried out after evaporation and crystallization. The crystallization makes the crystal size tend to be averaged, and at the same time the crystal surface grows to be smooth, and the crystal shape is improved; after the crystallization, cooling crystallization is carried out. Zone curve, design the cooling frequency of different cooling intervals. According to the preparation method of the present invention, after the crystallization is completed, the yield of the obtained crystals is high, the crystal size distribution is concentrated, and the crystal surface is smooth and mirror-like, with good light reflection and regular crystal forms.

The invention relates to a cefmenoxime hydrochloride composition for injection which consists of 10 parts by weight of cefmenoxime hydrochloride and 1.5 to 2.5 parts by weight of anhydrous sodium carbonate, preferably 10 parts by weight of cefmenoxime hydrochloride and 1.75 to 1.8 parts by weight of anhydrous sodium carbonate. The cefmenoxime hydrochloride is crystal, having characteristic peaks at the diffraction angles 2 theta of 6.0 degrees, 7.4 degrees, 11.0 degrees, 12.2 degrees, 17.5 degrees, 19.8 degrees, 21.6 degrees, 24.8 degrees and 27.7 degrees in the X-ray powder diffraction measured using a Cu K-alpha ray. The main crystal size of cefmenoxime hydrochloride is 30 to 45 microns and the crystal size distribution width is 25 to 75 microns. The cefmenoxime hydrochloride composition of the invention is in the dosage form of injection which is dissolved quickly, suitable for clinic application, good in stability and reliable in safety.

The invention discloses a multi-objective optimization method for intermittent sugarcane boiling and crystallization process, comprising the following steps: 1) constructing the variable value of the first initial gene; Carry out optimization to obtain the Pareto optimization solution set of the final crystal size distribution parameter; 3) carry out multi-objective decision-making to the Pareto optimization solution set of the final crystal size distribution parameter in step 2), and obtain the optimal final crystal size distribution parameter; 4) Construct the variable value of the second initial gene; 5) use the non-dominated sorting genetic algorithm to optimize the second initial gene in step 4), and obtain the Pareto optimization solution set of the first crystal size distribution parameter; 6) optimize the first crystal size Sorting the process variables corresponding to the Pareto optimization solution set of the distribution parameters; 7) outputting the result. The invention can obtain better optimization results to better guide the optimal control of the crystallization process of sugar cane boiling.

The invention discloses a preparation method and device of active microcrystalline fiber, place the prefabricated rod in the drawing furnace for wire drawing, the drawn fiber is induced by magnetic field in uncoated state and combined with laser treatment technology, the laser beam is focused on the fiber and recrystallized after laser treatment to obtain active microcrystalline fiber. Appropriate laser processing power directly affects the silicate glass fiber in the crystal structure, type, degree of crystallinity, grain size, content, and how much residual phase of glass. Induced by external magnetic field, the thermodynamics and dynamics of crystallization process are changed, make the crystal size distribution is better and uniform, reduce the phenomenon of condensation and makes the grain size is smaller.

The invention provides a high crystal density spheroidized NTO crystal and a preparation method thereof, wherein the NTO content in the crystal is ≥99.9%, the crystal density is ≥1.92g / cm3, the short-to-long axis ratio of the crystal is ≥0.90, and the crystal The median particle size ranges from 150 to 200 μm. The preparation method of the high crystal density spheroidized NTO crystal comprises the following steps: (1) adding NTO and a solvent into a reactor to fully dissolve, and the temperature of the reactor is 40-80°C; (2) lowering the reactor while stirring Temperature, after the formation of a supersaturated solution, crystal nuclei are formed and grow; (3) After the crystals are completely precipitated, stir at a low temperature of -5-0°C for 1-5 hours; (4) Filter, dry, and weigh. The crystal particle size distribution is narrow, the appearance observation crystal sphericity is high, the surface is smooth, and the crystal plane has no cracks.

The present invention provides a pigment particulate material selected from titanium dioxide, doped titanium dioxide and mixtures thereof, wherein said particulate material has an average crystal size of 0.3-0.5 microns and a crystal size distribution such that 40% by weight or more of the particulate material Having a crystal size of 0.3-0.5 microns, and wherein the ratio of average particle size to average crystal size is 1.25 or less. The pigmentary material is useful in compositions comprising the pigmentary material dispersed in a vehicle to provide improved opacity to the composition.