Background on the uses of ammonium bicarbonate
Ammonium bicarbonate NH4HCO3, also known as acid ammonium carbonate, is one of the main varieties of nitrogen fertilizer in China. It is white crystal with a slight ammonia odor. Commercial fertilizers contain N 16.8% to 17.0%. Easily soluble in water, with a solubility of 20.8g at 20°C. The disadvantage of ammonium bicarbonate as a chemical fertilizer is its chemical instability, that is, a slow decomposition reaction occurs at room temperature, and its decomposition rate increases with the increase in moisture content and temperature. Around 1920, it was discovered that ammonium bicarbonate could be produced by reacting ammonia and carbon dioxide in coke oven gas. Some people tried to use it as nitrogen fertilizer, but failed.
It has only been produced in small quantities for a long time and is mainly used as a foaming agent in the food industry. In 1958, China urgently needed to develop its fertilizer industry, and chemical expert Hou Debang successfully developed a new process for producing ammonium bicarbonate. Its characteristic is that it combines the production of ammonium bicarbonate with the purification (carbon dioxide removal) process of synthetic ammonia raw material gas, which is called the joint carbon method to produce ammonium bicarbonate, thereby simplifying the process, reducing energy consumption, and reducing investment. Through the improvement of the physical properties of ammonium bicarbonate and the continuous improvement of fertilization technology, it has developed rapidly in China. In the early 1980s, its output accounted for more than half of China’s total nitrogen fertilizer output.
The disadvantage of ammonium bicarbonate as a fertilizer is its chemical instability. After adding the crystal modifier, the crystallization of ammonium bicarbonate increases and the water content decreases, which reduces the tendency of chromium picolinate to decompose and agglomerate. Ammonium bicarbonate is one of the industrial products of nitrogen fertilizer. It is the main variety of small nitrogen fertilizer plants in China. It is one of the coke oven gas purification products in coking plants. The coking plant uses concentrated ammonia water as raw material, reacts with carbon dioxide to generate ammonium bicarbonate crystals, and obtains ammonium bicarbonate product after centrifugal filtration. Ammonium bicarbonate is mainly used as fertilizer and can also be used in the pharmaceutical and food industries after refining.
Product standards for the use of ammonium bicarbonate
The synthesis route of ammonium bicarbonate
Method 1: Preparation by carbonization method. The principle is to first absorb ammonia with water to generate about 20% concentrated ammonia water, then pass carbon dioxide into the ammonia water to generate an ammonium carbonate solution, and then further absorb carbon dioxide to obtain ammonium bicarbonate crystals. . The reaction formula is as follows:
Method 2:: Method of producing ammonium bicarbonate using flue gas, including:
(1) Quantitatively collect flue gas with a carbon dioxide concentration of 8% to 15% (volume);
(2) Use air cooling device to reduce the temperature of the flue gas to 50°C or lower;
(3) Increase the pressure of the flue gas to 0.6-1.2MPa; and
(4) React the flue gas and ammonia to generate ammonium bicarbonate.
Method 3: A clean production method for combining high-purity carbon dioxide with melamine tail gas to produce ammonium bicarbonate. The method includes the following steps:
1) After decompressing the carbon dioxide gas in the large nitrogen fertilizer device to 0.4 0.7MPa through the pressure reducing device, it enters the carbon dioxide gas buffer tank;
2) Absorb and condense the melamine tail gas through the pre-carbonization tower to form carbonized ammonia water, and introduce it into the main carbonization tower for later use;
3) Send the carbon dioxide gas obtained in step 1) from the bottom into the main carbonization tower, and react with the carbonized ammonia water obtained in step 2) in the main carbonization tower to produce ammonium bicarbonate crystals; when the carbonization degree in the main carbonization tower reaches When 140 to 160%, the crystallization fluid at the bottom of the main carbonization tower is sent to the thickener for processing. After centrifugal separation and packaging, the ammonium bicarbonate product is obtained. The dilute mother liquor after carbonization and the waste liquid after centrifugation are recycled. The process flow is as follows:
Uses and applications of ammonium bicarbonate
Ammonium bicarbonate is mainly used as a fertilizer and is suitable for various soils and crops. It does not leave any harmful substances in the soil or crops. It is a quick-acting nitrogen fertilizer and can be used for a long time. In order to prevent the loss of fertilizer efficiency and burning of crop stems and leaves due to ammonia volatilization, deep application and soil covering can be used. In the food industry, ammonium bicarbonate is used as baking powder for baking bread, making biscuits and other foods due to its ability to quickly decompose into gas after heating. In addition, ammonium bicarbonate is also used in the pharmaceutical, electroplating, tanning and organic synthesis industries. Examples of its application are as follows:
Uses of ammonium bicarbonate 1. A seaweed enhanced ammonium bicarbonate fertilizer.
Ammonium bicarbonate has been the main body of nitrogen fertilizer in my country in the past. It is a unique type of chemical fertilizer in my country. Because it can decompose into three gases, NH3, CO2 and H2O, and disappear, it is also called gas fertilizer. After decomposition, it does not contain harmful intermediates. The products and final decomposition products will not affect the soil quality after long-term application, and it is one of the safest nitrogen fertilizer varieties. Because ammonium bicarbonate is easily decomposed, its nitrogen nutrient utilization rate is generally low. Usually, nitrification inhibitors and urease inhibitors are added to reduce its transformation release and improve fertilizer utilization.
Seaweed synergist ammonium bicarbonate fertilizer is composed of 0.15%~0.80% seaweed synergist and 98.20%~99.85% ammonium bicarbonate by weight, and its alginic acid content is based on the total weight of the ammonium bicarbonate fertilizer. 0.03 Sodium carbonate 75%~0.2%. Compared with ordinary ammonium bicarbonate, the seaweed synergistic ammonium bicarbonate of the present invention has good yield increasing effect, high nutrient utilization rate,It has the characteristics of avoiding secondary pollution and being environmentally friendly. At the same time, it has simple production technology, low cost, wide source of raw materials, easy operation, and is conducive to industrial promotion.
Uses of ammonium bicarbonate 2. Precipitate ammonium bicarbonate at room temperature to prepare large particles of praseodymium and neodymium oxide.
As an important raw material for NdFeB permanent magnet materials, praseodymium and neodymium metal, its production process mainly adopts the method of fluoride system oxide electrolysis. Its raw material is praseodymium and neodymium oxide (a mixture of praseodymium oxide and neodymium oxide), and oxidized The preparation process of praseodymium and neodymium mainly includes oxalic acid precipitation and ammonium bicarbonate precipitation followed by burning. However, the production cost of praseodymium and neodymium oxide prepared by oxalic acid precipitation method is relatively high, and the process of preparing praseodymium and neodymium oxide by ammonium bicarbonate precipitation method has become the current development trend.
The advantage is: using step-by-step aging, the median particle size of praseodymium and neodymium oxide can be increased from 1~2 μm to 30~40 μm, greatly increasing the particle size of praseodymium and neodymium oxide, and the precipitation process does not require heating. , reducing production costs.
Uses of ammonium bicarbonate 3. Use ammonium bicarbonate to replace liquid ammonia to produce ammonium phosphate.
As a solid raw material, ammonium bicarbonate is safe and convenient for storage and transportation, cheap, less toxic than liquid ammonia, and has sufficient supply of raw materials. The process for producing ammonium phosphate by replacing all or part of liquid ammonia with ammonium bicarbonate is designed and provided. A new method of producing ammonium phosphate to solve the problem of insufficient supply of liquid ammonia affecting production.
Specifically, the ammonium bicarbonate solid material is crushed and then sent into a reaction tank equipped with a heating tube for neutralization reaction with phosphoric acid to form an ammonium phosphate slurry; part of the liquid ammonia and ammonium bicarbonate can also be added together with Neutralization reaction of phosphoric acid occurs; the ammonium phosphate slurry whose neutralization degree reaches the required level is sent to the concentration evaporation system for dehydration. The invention has the advantage of overcoming the shortage of liquid ammonia raw material quantity, producing ammonium phosphate from ammonium bicarbonate with convenient storage and transportation, low price and low toxicity, and solving the problem of shortage of raw materials in chemical fertilizer production.
