In order to solve the problems such as material filtration difficulty and paste transfer difficulty existing in the prior art of sulfamic acid production technology, the present invention proposes a more concise and rapid post-treatment process.
The present invention adopts conventional methods to prepare sulfamic acid. The so-called conventional method refers to the method in which urea is sulfonated with oleum to produce sulfamic acid. For those skilled in the art, its preparation method can be known from a number of references such as charging ratio, reaction conditions and operation steps and the like. The creative contribution made by the present invention is to provide a new post-processing process, which enables people to abandon the post-processing methods reported in the previous literature, and adopts a new post-processing method that does not require multiple material transfers and special equipment, and can obtain high-quality, high yield of the desired product.
The technical scheme of the sulfamic acid production technique provided by the invention is as follows:
After the reaction, add dilute sulfuric acid with a concentration of 5-30% to adjust the concentration of sulfuric acid in the reactor to between 60-75%, and separate the upper layer sulfuric acid after standing; then add dilute sulfuric acid with a concentration of 1-10% or water, adjust the sulfuric acid concentration in the kettle to between 5-20%, recrystallize, filter and dry to obtain the high-purity target product.
According to the post-treatment process of the present invention, after the reaction is completed, the temperature of the first material is lowered to 40°C. About C, carry out the first acidity adjustment treatment by adding dilute sulfuric acid. The preferred concentration of dilute sulfuric acid added to the reactor this time is about 10-25%. Because in actual production, the concentration of the filtrate obtained by filtration after recrystallization of the product is just within this range, and it can be recycled and used for adjusting the acidity this time. The concentration of the first acidity adjustment is preferably between 65-70%. At room temperature, the solubility of sulfamic acid in 70% sulfuric acid is extremely small, and the difference in specific gravity between the two is relatively large. Therefore, when the acidity is adjusted properly, stirring is stopped, and after standing for a while, although the sulfamic acid particles precipitated from 70% sulfuric acid are very fine. Difficult to filter, but can settle down faster. Using this feature, the sulfuric acid in the upper layer can be easily separated (with almost no entrained product). In actual operation, a movable pipe with a suitable opening position can be used to extract this part of sulfuric acid (about 70% of the total sulfuric acid in the kettle) from the upper part of the reaction kettle. The extracted sulfuric acid (concentration about 70%) can be sold to other manufacturers as a by-product.
After that, the material in the kettle can be directly recrystallized without transferring. The specific operation method is as follows: first, carry out the second acidity adjustment, add dilute sulfuric acid with a concentration of 1-10% or directly add water, adjust the sulfuric acid concentration in the kettle to not more than 20%, and control the appropriate acid concentration between 5-20% . If the concentration is higher than 20%, the quality of the product will decrease; if the concentration is lower than 5%, the amount of waste acid will increase and the cost of treatment of the three wastes will increase. In actual production, the amount of dilute sulfuric acid used for the second acidity adjustment or water is that the weight ratio of sulfamic acid and dilute sulfuric acid or water is between 1: 2-1: 7, so that both can guarantee to obtain high-quality product, and The amount of waste acid can be effectively controlled. Heating to make the sulfamic acid completely dissolved, pay attention to the temperature should not exceed 75 °C. After that, the temperature is lowered to precipitate sulfamic acid crystal particles. Filtration and drying were carried out to obtain aminosulfonic acid with a purity of more than 99.5%, and the yield was about 85%.
The post-treatment process of the present invention has the following advantages: the acid discharge and refining operations in the sulfamic acid production process are arranged
Carry out in the same reaction kettle, thoroughly solve many problems such as high labor-intensity transfer material, multiple filtration, multiple recrystallization purification or use of pressurized equipment to increase production cost in the prior art. Only one filter is required in the post-processing operation, and is
Because of the good crystal form of the product, the filtering operation is very easy. Using conventional equipment, filtering 850 kg of product can be completed in 0.5 to 1 hour. Therefore, the post-processing process provided by the present invention is easy to operate, low in labor intensity of workers, high in product yield and good in quality. At the same time, 70% sulfuric acid with a concentration of 70% can be recovered to the maximum extent for sale as a by-product, and most of the dilute sulfuric acid can be recycled and applied.