Soda ash production process

Soda ash is soda, with the chemical formula Na2CO3. It is an important chemical raw material and a necessity for industries such as food, papermaking, pharmaceuticals, glass, soap, printing and dyeing, and even people's daily lives. 1: Bran's alkali production method: In ancient times, people extracted potassium carbonate from plant ash, and later obtained sodium carbonate from natural resources such as saline-alkali land and salt lakes, but the amount was too small. It is far from meeting the needs of chemical production. In 1791, the French doctor Lou Blanc first obtained the patent for making alkali. He used table salt as raw material to make alkali, which was called Lou Blanc's method of making alkali. This method was divided into three parts.: ①Reaction of sodium chloride and sulfuric acid to produce sodium sulfate: 2NaCl+H2SO4=Na2SO4+2HCl ； ②Reduction of sodium sulfate with coke to obtain sodium sulfide: Na2SO4+4C=Na2S+4CO↑ ③React sodium sulfide and limestone to produce sodium carbonate: Na2S+CaCO3=Na2CO3+CaS Disadvantages: This method requires high temperature during production, sulfuric acid seriously corrodes equipment, CaS waste accumulates for a long time and emits odor, and the cost is high, so it was later replaced by the ammonia-alkali method. 2: The ammonia-alkali method is the Solvay alkali production method. It was invented by the Belgian Solvay in 1862 using salt, ammonia, and carbon dioxide as raw materials. The reaction is also carried out in three steps.: ①NH3+CO2+H2O=NH4HCO3 ②NH4HCO3+NaCl=NaHCO3+NH4Cl ③2NaHCO3=Na2CO3+CO2↑+H2O The CO2 generated by the reaction can be recycled, and NH4Cl can react with quicklime to regenerate ammonia gas.: 2NH4Cl+CaO=2NH3↑+CaCl2+H2O Disadvantages: This method realizes continuous production, improves the utilization rate of salt, and reduces the price of soda ash. * * Reduced, and the product quality is pure, so it is called soda ash. Three: Hou's alkali production method has greatly improved the above method. The biggest feature of this method is that it does not use solid ammonium bicarbonate (NH4HCO3), but uses brine to absorb ammonia first and then carbonate it for continuous production. The principle of this method is: At low temperature, sodium bicarbonate (NaHCO3) can be precipitated by passing carbon dioxide (CO2) into saturated salt water saturated with ammonia. At this time, the Na+ in the mother solution is reduced and Cl- is relatively high. At this time, fine salt powder is added. Due to the same ion effect, the solubility of low-temperature ammonium chloride (NH4Cl) suddenly decreases, while the solubility of table salt (NaCl) does not change much, so ammonium chloride (N H4Cl) precipitates but table salt does not, and then saturates it with ammonia and then passes through carbon dioxide (CO2). As a result, NaHCO3 and NH4Cl precipitate back and forth. Ammonia is made by combining nitrogen with hydrogen in water. CO2 is a by-product of semi-water gas that extracts hydrogen and nitrogen. This cleverly combines the nitrogen industry and the alkali production industry, so Hou's alkali production method is also called the combined alkali production method. The alkali produced by this method is of excellent quality and is as pure as snow. In 1926, it won the "Gold Medal of the World's Fair" in Philadelphia, USA. This is specifically the case: 1 Pour carbon dioxide NH3+H2O+CO2+NaCl=NH4Cl+NaHCO3 into the ammoniated saturated brine (precipitation) 2 Heat sodium bicarbonate to obtain sodium carbonate 2NaHCO3=Na2CO3+H2O+CO2 3 Use sodium carbonate to pour lime water to produce sodium hydroxide Na2CO3+Ca(OH)2=2NaOH+CaCO3 4 Calculate calcium carbonate to obtain carbon dioxide cycle CaCO3=CaO+CO2 CaO+H2O=Ca(OH)2 5. Add excess salt to the mother liquor of the 1-step reaction, and ammonium chloride crystallizes out to be used as fertilizer. After thousands of experiments, Mr. Hou Debang successfully researched the joint alkali production method in 1943. This method combines the production of synthetic ammonia and soda ash, which improves the utilization rate of salt, shortens the production process, reduces environmental pollution, and reduces the cost of soda ash.

The content is very rich and will be very helpful to me in my future work.

support! Thank you so much! We are collecting materials, they may come in handy

The most important thing in making soda ash is the carbonation process, and the one that directly affects the final result is the calcination process.

Reply 1# * aona2010 1. Ammonia-alkali method (also known as Solvay method) It is a soda ash production method invented by Belgian engineer Solvay (1838-1922) in 1892. He used table salt (sodium chloride), limestone (calcined to produce quicklime and carbon dioxide), and ammonia as raw materials to produce soda ash. First, ammonia gas is passed into saturated brine to form ammonia salt water, and then carbon dioxide is introduced to form sodium bicarbonate precipitate and ammonium chloride solution with low solubility. The principle of its chemical reaction is: NaCl+NH3+H2O+CO2=NaHCO3↓+NH4Cl The NaHCO3 tiny crystals obtained after filtration and washing are then heated and calcined to obtain a soda ash product. 2NaHCO3＝Na2CO3＋H2O＋CO2↑The carbon dioxide gas released can be recovered and recycled. The filtrate containing ammonium chloride is mixed with lime milk and heated, and the ammonia released can be recovered and recycled. CaO+H2O=Ca(OH)2, 2NH4Cl+Ca(OH)2=CaCl2+2NH3↑+2H2O The advantages of ammonia-alkali method are: Raw materials (salt and limestone) are cheap ； Product soda ash has high purity ； Both the by-products ammonia and carbon dioxide can be recovered and recycled ； The manufacturing steps are simple and suitable for mass production. However, the ammonia-alkali method also has many disadvantages: First of all, only half of the ingredients of the two raw materials are used - the sodium ions (Na+) in the salt component and the carbonate ions (CO32-) in the limestone component are combined to form sodium carbonate, but the other component of the salt, the chloride ion (Cl-), and the other component of the limestone, the calcium ion (Ca2+) are combined to form calcium chloride (CaCl2), which has little use. Therefore, how to deal with calcium chloride becomes a big burden. The biggest disadvantage of the ammonia-alkali method is that the utilization rate of raw salt is only 72% to 74%. The rest of the salt is discarded along with the calcium chloride solution as waste liquid, which is a big loss. 2. Combined alkali production method (also known as Hou's alkali production method) It was founded in 1943 by Hou Debang (1890 ~ ​​1974), a Chinese chemical engineering expert. It is a method that combines the ammonia-alkali method and the synthetic ammonia method to produce two products, soda ash and ammonium chloride. The raw materials are salt, ammonia and carbon dioxide - waste gas from ammonia plants that produce hydrogen from water gas. The principle of its chemical reaction is: C＋H2O＝CO＋H2 CO＋H2O＝CO2＋H2 The combined alkali production method includes two processes: The first process is the same as the ammonia-alkali method. Ammonia is passed into saturated brine to form ammonia salt water, and then carbon dioxide is introduced to form sodium bicarbonate precipitate. After filtration and washing, NaHCO3 tiny crystals are obtained, and then calcined to obtain a soda ash product. The filtrate is a solution containing ammonium chloride and sodium chloride. The second process is to crystallize and precipitate ammonium chloride crystals from the filtrate containing ammonium chloride and sodium chloride. Because the solubility of ammonium chloride is greater than that of sodium chloride at room temperature, its solubility is smaller than that of sodium chloride at low temperatures, and the solubility of ammonium chloride in a concentrated solution of sodium chloride is much smaller than that in water. Therefore, under low temperature conditions, finely powdered sodium chloride is added to the filtrate and ammonia gas is introduced, so that ammonium chloride can be crystallized and precipitated separately. After filtering, washing and drying, the ammonium chloride product can be obtained. At this time, the filtrate obtained after filtering out the ammonium chloride precipitation is basically saturated with sodium chloride and can be recovered and recycled. Compared with the ammonia-alkali method, the biggest advantage of the combined alkali production method is that it increases the utilization rate of salt to more than 96%. The same amount of salt can be used to produce more soda ash than the ammonia-alkali method. In addition, it comprehensively utilizes the carbon dioxide from the ammonia plant and the chloride ions from the alkali plant, and at the same time, produces two valuable products - soda ash and ammonium chloride. The waste gas carbon dioxide of the ammonia plant is converted into the main raw material of the alkali plant to produce soda ash, thus saving the huge lime kiln used to produce carbon dioxide in the alkali plant. ； The useless component chloride ion (Cl-) in the alkali plant is used to replace the more expensive ammonia in the sulfuric acid fixed ammonia plant to produce nitrogen fertilizer ammonium chloride. This eliminates the generation of calcium chloride, which is of little use and is difficult to handle, reducing environmental pollution and * * It reduces the cost of soda ash and nitrogen fertilizer and fully reflects the advantages of large-scale joint production.

The main production processes include ammonia-alkali method, combined alkali method and Japan's New Asahi method. In China, the main method is the ammonia-alkali method, and some companies use the combined alkali method. However, due to environmental protection problems, some companies are currently changing to joint alkali.