The method of producing sodium formate
(57) Abstract:Usage: salts of lower aliphatic acids, in particular sodium formate used in tanning and chemical industries. The essence of the invention: sodium formate is produced by evaporation of the mother liquor obtained after separation of pentaerythritol from the reaction mass condensation of formaldehyde with acetaldehyde in the presence of sodium hydroxide. Crystallization of sodium formiate of the solution are under vacuum at a residual pressure of 6oC2 kPa with simultaneous evaporation of the water in the amount of 10oC20% by weight of the initial solution and cooling it to a temperature of 55oC70oC with a speed of 1.5oC3 degrees per minute. Then carry out the filtration and drying of the finished product. 1 C.p. f-crystals, 1 table. The invention relates to the chemical industry, in particular, to the production of sodium formate used in tanning, chemical and other industries.A method of obtaining sodium formate, based on the interaction of sodium hydroxide with carbon monoxide /1/. The process occurs at a temperature of 240oC250oC and high pressure. The resulting product is subject to the closest set of features to the present invention is a method of producing sodium formate from the mother liquor, obtained after separation of pentaerythritol from the reaction mass condensation of formaldehyde with acetaldehyde in the presence of sodium hydroxide /2/.The method consists in evaporating the mother liquor obtained after separation of pentaerythritol crystallization, which contains dissolved sodium formate in the number 44oC48% residual quantity of pentaerythritol in the amount of 8oC10% and other technological admixture to a value of density equal to 1400oC1450 kg/m3and crystallization from the evaporated solution of sodium formiate.The crystallization is carried out by cooling the evaporated solution to a final temperature equal to 25oC40oC in the crystallizers operating under atmospheric pressure and equipped with a frame with stirring and cooling jackets. The process duration is 2.5oC4 hours, and the cooling rate is in the range of 0.15oC0,5 degrees per minute. The precipitate of sodium formiate filtered, dried and Packed in bags.The advantage of this method is low cost get technical sodium formate, and the lack of its relatively low quality. Miscellania from the mother liquor of pentaerythritol. After evaporation of the impurity concentration of pentaerythritol rises further and subsequent cooling of the solution, it becomes supersaturated not only sodium formiate, but also on the impurities of pentaerythritol. As a result, the crystallization along with furminator sodium in the solid phase manages to stand out and a significant amount of impurities pentaerythritol, which contaminate the finished product.The proposed method of obtaining sodium formiate, including the evaporation of the mother liquor obtained after separation of pentaerythritol from the reaction mass condensation of formaldehyde with acetaldehyde in the presence of sodium hydroxide, crystallization by cooling, filtering and drying of sodium formiate, characterized in that the crystallization of sodium formiate are under vacuum at a residual pressure of 2oC6 kPa while evaporating and removing part of the water in the quantity of 10oC20% by weight of the solution and cooling it to 55oC75oC with a speed of 1.5oC3 degrees per minute.The results of our studies have established that the pentaerythritol in the presence of significant quantities of sodium formiate within a certain period of time, not to the quick crystallized even at low its solution.The inventive method allows to significantly improve the quality of sodium formiate by reducing the content of impurities of pentaerythritol. This is achieved by maintaining the technological regime, which to the maximum extent take into account we have set out the differences in the crystallization of sodium formate and pentaerythritol.With the increase of the residual pressure in the vacuum crystallizer greater than 6 kPa not achieved the desired end temperature of the cooling 55oC75oC. Reduction of residual pressure less than 2 kPa does not provide any additional benefits on cooling, but increases the energy consumption for the vacuum.The decrease in the degree of removal of water from the evaporated mother liquor is less than 10% leads to a significant decrease in the excretion of sodium formiate in the solid phase that is not economically feasible. The increase in the degree of removal of water more than 20% is unacceptable as entails a reduction of the quality of the product.Increasing the final temperature of crystallization of more than 75oC is undesirable because it reduces the discharge of sodium formate in the solid phase. The reduction temperature is less than 55oC what about the equipment and reduce the quality of the finished product.The decrease in the cooling rate of the solution is less than 1.5 degrees per minute leads to deterioration in the quality of sodium formiate. This is because at such slow cooling duration of the crystallization process exceeds the incubation period of the existence of supersaturated solution of pentaerythritol and he manages largely to stand out together with sodium formate in the solid phase. Increasing the cooling rate of more than 3 degrees per minute is also unacceptable because it does not give additional quality improvement, but significantly reduces the size of the resulting crystals formiate sodium. This deficiency in turn complicates the job of filtering and drying equipment and incurs higher losses of product.The proposed process can be carried out as follows.The mother liquor obtained after separation of pentaerythritol from the reaction mass condensation of formaldehyde with acetaldehyde in the presence of sodium hydroxide, subjected to concentration by evaporation to a density equal to 1450oC1500 kg/m3and sent to the crystallization of sodium formiate.Crystallization was carried out in vacuum crystallia drainage resulting juice water vapor, which condenses in the condenser. The resulting juice condensate in the amount of 10oC20% by weight of the initial solution is removed at a technological need or for biological treatment. The remaining part of the condensate in the form of phlegmy return back to the crystallizer. The residual pressure in the vacuum crystallizer maintained within the range of 6oC2 kPa using a vacuum pump. The cooling solution is conducted at the rate of 1,5oC3 C per minute to a final temperature equal to 55oC75oC.Obtained after crystallization, the suspension is filtered in a centrifuge, balance of technical sodium formate dried in Aeropostale dryer and Packed in bags.For the detail of the above provide examples of the proposed method in the inventive modes. To map a drive is also an example implementation of the process according to the prior art (example 1), conducted in pilot conditions in Gubakha JSC "Metafrax".Example 1. The mother liquor in the number 3533 kg, obtained after separation of pentaerythritol from the reaction mass condensation of formaldehyde with acetaldehyde in the presence of sodium hydroxide, is mixed with part of the liquid fasch/m3. The evaporated solution in a number 3038 kg and containing in its composition 1378 kg of sodium formiate, 298 kg of PENTAERYTHRITE and some other process impurities are sent to the crystallization of sodium formiate. Crystallization lead to atmospheric pressure by cooling the evaporated solution at a rate of 0.2 degrees per minute to a final temperature equal to the 37oC. the Process is carried out in a crystallizer equipped with a frame with stirring and cooling jackets. The resulting suspension of sodium formiate share in the centrifuge, the wet sediment in the amount of 1050 kg dried to a residual moisture content of 0.5% and prepared a technical product (1000 kg) Packed in bags.Example 2. Conditions analogous to example 1. The differences consist in the fact that the crystallization of sodium formate is carried out in a vacuum crystallizer at a residual pressure of 6 kPa. Juice, water vapor is removed from the mold, condense in the condenser-the condenser and in the amount of 20% by weight of the initial solution is removed for technological needs. The remainder of the juice condensate in the form of phlegmy return back to the crystallizer. The cooling rate of the solution in the crystallizer support equal to 1.5 degrees in minutesby when others declare the parameters presented in the table.From the experimental data it follows that the proposed method can reduce the mass fraction of impurities in the resulting product from 15 to 3.5% Simultaneously greatly increases the productivity of crystallization equipment. The method of producing sodium formiate, including the evaporation of the mother liquor obtained after separation of pentaerythritol from the reaction mass condensation of formaldehyde with acetaldehyde in the presence of sodium hydroxide, crystallization by cooling, filtering and drying of sodium formiate, characterized in that the crystallization process are under vacuum at a residual pressure of 2 to 6 kPa while evaporating and removing part of the water in an amount of 10 to 20% by weight of the solution and cooling it to a temperature of 55 to 75oWith speeds of 1.5 to 3 deg/min
FIELD: radiochemical industry.
SUBSTANCE: proposed method includes crystallization of uranyl hexahydro-nitrate from solution by cooling it down. In the process uranyl nitrate solution is pre-evaporated to uranium concentration of 800-1300 g/l and to nitric acid concentration of 0.5-3.0 mole/l. Crystallization is conducted in concurrent flow of uranyl hexahydro-nitrate crystals formed in the process and mother solution while permanently stirring and cooling solution to 15-30 oC. Crystals are separated from mother solution and washed in concurrent flow at 15-30 oC in wash solution containing 250-300 g/l of uranium and 3.0-6.0 mole/l of nitric acid. Then crystals are taken out and dried. Device implementing this method has crystallization vat made in the form of externally cooled tube. In addition vertically disposed crystallization vat accommodates blade mixer. Uranyl nitrate solution feed union is disposed in top part of crystallization vat. Bottom part of the latter is placed coaxially with wash-over string and secured in hole of its lid provided with pipe union for joint outlet of mother solution and waste wash solution. Bottom part of wash-over string is joined at certain angle to auger-accommodating inclined tube. Top part of inclined tube is provided with pipe union for taking out dried uranyl hexahydro-nitrate crystals and wash solution feed union. Pipe union for taking out dried crystals is disposed above that wash solution feed union. Pipe union for feeding uranyl nitrate solution is level with wash solution feed union and with water seal.
EFFECT: enhanced cleaning efficiency and economic efficiency of process.
7 cl, 2 ex
FIELD: processing of the waste nuclear fuel.
SUBSTANCE: the invention is pertaining to the field of processing of the waste nuclear fuel, in particular to the method and for purification of the waste nuclear fuel from the fission products and a device for its realization. The invention provides, that uranyl nitrate solution is evaporated up to the concentration in respect to uranium of 800-1300 g/l and to nitric acid of 0.5-3.0 mole/l. Crystallization is conducted in a forward flow of the being formed crystals of hexahydrate of uranyl nitrate and a mother liquor at constant chilling of the solution up to temperature of 15-30°C. The formed crystals are separated from the mother liquor and subjected to the countercurrent washdown at the temperature of 15-30°C by a washing solution containing 250-300 g/l of uranium and 3.0-6.0 mole/l of nitric acid. Then the crystals are separated from the washing solution, smelt at the temperature exceeding 60°C and discharge under the action of a difference of the hydrostatic pressure. The for purification of uranyl nitrate from the fissing products contains a crystallizer made in the form of a pipe with external chilling and supplied with the union of the uranyl nitrate solution feeding. The device has the U-shaped form and is mounted upright. On one side of the device in its upper part there is a crystallizer with a union for uranyl nitrate solution feeding. The lower part of the crystallizer is mounted coaxially to the washing column. The cover is supplied with a union for a joint withdrawal of the mother liquor and the spent washing solutions. The lower part of the washing column has a conical bottom and is supplied by the union of feeding a washing solution. The other side of the device is made in the form of the pipeline. In the lower part the pipeline is connected to the conical bottom of the washing column and a pulsation cylindrical chamber, and in the upper part the pipeline is supplied by a drain connection. Advantages of the invention consist in simplification of the method and improved degree of a purification efficiency.
EFFECT: the invention ensure simplification of the method and an improved degree of purification efficiency.
5 cl, 2 dwg, 2 ex
SUBSTANCE: device comprises mixer and crystallizer that has at least of one evaporator. The evaporator has outer pipe, inner pipe, and rotating member mounted in the inner pipe. The rotating device comprises rotating shaft and one scraper mounted on it. The angle between the inner side of the scraper and the diameter of the inner pipe should prevent the crystals to grow on the inner side of the evaporator. The method comprises mixing liquid with the gas and causing the mixture to flow through at least one evaporator for three-dimensional crystallization. The mixture flows through the inner pipe of the evaporator where it is set in rotation by means of rotating device.
EFFECT: reduced power consumption and enhanced efficiency.
22 cl, 5 dwg