[Soda Ash Knowledge] Daily Question (57) 11/29/2009

The combined alkali production process: (1) NH3 + H2O + CO2 = NH4HCO3; (2) NH4HCO3 + NaCl = NH4Cl + NaHCO3↓; (3) 2NaHCO3 → heating → Na2CO3 + H2O + CO2↑. Ammonia reacts with water and carbon dioxide to form one molecule of ammonium bicarbonate, which is the first step. The second step is: ammonium bicarbonate reacts with sodium chloride to produce one molecule of ammonium chloride and sodium bicarbonate precipitate; sodium bicarbonate precipitates because its solubility is very low. Based on the principle that NH4Cl has a higher solubility at room temperature than NaCl, but lower solubility at low temperatures, fine table salt powder is added to the mother liquor at 278K–283K (5℃–10℃), allowing NH4Cl to crystallize out separately for use as a nitrogen fertilizer. Advantages of this method: it retains the advantages of the ammonia-alkali method while eliminating its disadvantages, thereby increasing the utilization rate of table salt to 96% ； NH4Cl can be used as a nitrogen fertilizer ； It can be combined with ammonia synthesis plants to convert the CO in the raw material gas used for ammonia synthesis into CO2, thereby eliminating the process of producing CO2 from CaCO3. Disadvantages: Large amount of mother liquor circulation, high power consumption

This post was last edited by mgdtcc on 2009-11-29 at 13:32. 1# chen3jun Advantages: 1. Combined with ammonia synthesis plants to turn waste into treasure； (It demonstrates the advantages of large-scale joint production, by using the waste from one factory as the main raw material for another factory.) ) The 2 mother liquors are recycled, **increasing the utilization rate of table salt to >98%** ； 3. Simple operation, simple factory equipment, and low cost. (By linking the production of soda ash with that of ammonia, the need for lime kilns and equipment for ammonia vaporization in the production of carbon dioxide is eliminated; the hassle associated with handling calcium chloride is removed as well, and the chloride ions present in table salt are fully utilized to produce two valuable substances, thereby reducing costs.) 4. Compared with the ammonia-alkali process, the combined alkali production method features a higher utilization rate of raw materials, transforms waste into valuable resources, and causes less environmental pollution. Disadvantages: 1. It is difficult to control the purity of soda ash. 2. Water balance is a challenge. 3. The market for ammonium chloride affects soda ash production

Advantages: ① High utilization rate of raw materials; ② No need to install large-scale equipment such as lime kilns, lime slaking machines, and distillation towers for soda ash production, resulting in cost savings; ③ Reduction of large amounts of waste residue and liquid waste, thereby minimizing environmental pollution; ④ Production of nitrogen fertilizer, ammonium chloride. Disadvantages: ① Large volume of mother liquor is required for production and recycling, resulting in high energy consumption and low equipment utilization efficiency; ② It is difficult to control the equilibrium of the mother liquor; ③ Ammonium chloride mother liquor is highly corrosive, requiring stringent anti-corrosion measures.

This post was last edited by yao091020 on 2009-11-29 at 14:03. 1. High raw material utilization rate. 2. In soda ash production, there is no need to install bulky equipment such as lime kilns, lime slaking machines, or distillation towers; this reduces the capital investment required for plant construction by 1/4, and there is no generation of large amounts of waste liquid or slag. 3. The combination of the soda ash industry and the synthetic ammonia industry has the drawback that 1. the mother liquor after ammonia production contains a high level of fixed ammonia, resulting in less soda ash being obtained per unit volume of this mother liquor. 2. Due to the recycling of mother liquor in caustic soda production, the water volume in the system must remain in balance or show a slight downward trend. Otherwise, an increase in the amount of mother liquor makes treatment difficult and increases losses. Therefore, it is necessary to strictly control the mother liquor balance. 3. The high concentration of ammonium chloride in the circulating mother liquor makes it highly corrosive, which can shorten the lifespan of equipment and buildings.

Advantages: 1. High utilization rate of raw materials. 2. No need to build large-scale equipment such as lime kilns, slaking machines, or distillation towers for soda ash production, thus saving on investment. 3. Reduction of large amounts of waste residue and liquid waste, thereby minimizing environmental pollution. 4. Enables the production of nitrogen fertilizer in the form of ammonium chloride. Disadvantages: 1. Large volume of mother liquor required for production and recycling, high energy consumption, and low utilization efficiency of equipment space. 2. Difficult control of mother liquor balance. 3. The ammonium chloride mother liquor is highly corrosive, requiring stringent anti-corrosion measures

Advantages: (1) High raw material utilization rate； (2) In soda ash production, there is no need to install large-scale equipment such as lime kilns, lime slaking machines, and distillation towers, thus saving on investment ； (3) Eliminate large amounts of waste residue and liquid waste, reducing environmental pollution ； (4) Produce nitrogen fertilizer, ammonium chloride. Disadvantages: (1) Large volume of production and recycled mother liquor required, high power consumption for pumps, and low equipment volume utilization efficiency ； (2) It is difficult to control the mother liquor equilibrium ； (3) The ammonium chloride mother liquor is highly corrosive, requiring stringent anti-corrosion measures.

Advantages: 1. High raw material utilization rate. 2. No need to build large-scale equipment such as lime kilns, slaking machines, or distillation towers for soda ash production, thus saving investment. 3. A large amount of waste residue and liquid waste is eliminated, reducing environmental pollution. 4. Ammonium chloride, a nitrogen fertilizer, can be produced. Disadvantages: 1. The volume of the mother liquor used in production and recycling is large, resulting in high energy consumption and low equipment capacity utilization. 2. It is difficult to control the balance of the mother liquor. 3. The ammonium chloride mother liquor is highly corrosive, requiring stringent anti-corrosion measures

I. Advantages 1. High raw material utilization rate； 2. No need to build large-scale equipment such as lime kilns, lime slaking machines, or distillation towers, resulting in cost savings ； 3. Eliminate large amounts of waste residue and liquid waste, reducing environmental pollution ； 4. Ammonium chloride is generated simultaneously. II. Disadvantages: 1. Large amounts of mother liquor are produced and recycled, resulting in high energy consumption and low utilization efficiency of solvents in the equipment ； 2. Mother liquor equilibrium control is relatively difficult ； 3. The ammonium chloride mother liquor is highly corrosive, requiring high standards for corrosion resistance

Advantages: 1. High utilization rate of raw materials. 2. No need to build large-scale equipment such as lime kilns, lime dissolving machines, or distillation towers for soda ash production, thus saving investment. 3. Eliminates a large amount of waste residue and liquid waste, reducing environmental pollution. 4. Enables the production of nitrogen fertilizer, ammonium chloride. Disadvantages: 1. Large volume of mother liquor is generated during production and in the recycling process, resulting in high energy consumption and low volumetric efficiency of the equipment. 2. It is difficult to control the balance of the mother liquor. 3. The ammonium chloride mother liquor is highly corrosive, requiring stringent anti-corrosion measures

Advantages: 1. High utilization rate of raw materials. 2. No need to build large-scale equipment such as lime silos, lime dissolving machines, or distillation towers for soda ash production, thus saving investment. 3. A large amount of waste residue and liquid waste is eliminated, reducing environmental pollution. 4. Ammonium chloride, a nitrogen fertilizer, can be produced. Disadvantages: 1. A large volume of mother liquor is generated during production and recycling, resulting in high energy consumption and low volumetric efficiency of the equipment. 2. It is difficult to control the balance of the mother liquor. 3. The ammonium chloride mother liquor is highly corrosive, requiring stringent anti-corrosion measures. 1# chen3jun