Successful pilot production of nitro-sulfur compound fertilizers by Luxi Group

After years of hard work, it was finally successful

This post was last edited by ztbxx on 2016-7-30 at 11:48. http://www.lcxw.cn/d/file/news/liaocheng/yc/2016-07-29/f77914a719f1ff8452fd0e1b9d45ce8f.jpg The main methods for producing compound fertilizers both domestically and internationally are as follows: 1) Slurry method – Using phosphoric acid and ammonia as raw materials, a neutralized slurry is coated and granulated in an ammoniation granulator through the use of neutralizers and tubular reactors. During the production process, nitrogen, potassium, and other substances are added, and after drying, screening, and cooling, NPK compound fertilizer products are obtained. This is the production method commonly used by major fertilizer companies and factories around the world for large-scale production. Phosphoric acid can be produced by decomposing phosphate rock with sulfuric acid; when conditions permit, commercial phosphoric acid can also be purchased directly to reduce investment and simplify the production process. The advantage of this method is that it enables the production of both ammonium phosphate and NPK fertilizers; at the same time, it makes use of the heat of neutralization between acid and ammonia to evaporate the moisture from the materials, thereby reducing the water content in the granules and the drying load, and cutting energy consumption. The advantages of this method include large production scales, lower production costs, good product quality, and high product strength. Since phosphate and sulfuric acid plants usually need to be built concurrently, such construction requires large investments and long time frames. It also involves the supply of phosphorus and sulfur resources as well as numerous environmental protection issues (such as phosphogypsum, fluorine, acid foam, and acid sludge). Therefore, it is generally more suitable for use in phosphate ore processing bases where large-scale production takes place with a limited variety of products. If commercially purchased phosphoric acid is used as the raw material, stable sources, transportation issues, and price factors must be taken into consideration. In recent years, thanks to the improvement in technology and equipment levels in China’s phosphate industry, favorable conditions have emerged for wet-process phosphoric acid to enter the market as a commodity. Establishing phosphate production bases in areas that possess the necessary resources and conditions, so as to supply commercial phosphoric acid to meet the needs of other regions for high-concentration phosphate fertilizers, is becoming a new approach. Market demand will surely drive the development of this industry and also help address the issue of raw phosphate supply in many regions. The foreign companies that possess this production technology include Norwegian Norsk Hydro, Spanish Incro and Espindsea, French AZF and KT, and American Davy/TVA, among others. The main domestic manufacturers include: China-Arab Fertilizer Co., Ltd., Jiangxi Guixi Fertilizer Factory, Yunnan Yunfeng Chemical Company, Nanjing Nanhua Phosphate Fertilizer Factory, Dalian Chemical Plant, Jinchang Chemical Company, Guangxi Luzhai Phosphate Fertilizer Factory, and others. The domestic enterprises that possess production technologies similar to this include Red Sun Group in Shandong, Chengdu University of Science and Technology in Sichuan, and the Shanghai Institute of Chemical Industry, among others. 2) Solid granulation method: Using single-component basic fertilizers such as urea, **, ammonium chloride, ammonium sulfate, ammonium phosphate (monoammonium phosphate, diammonium phosphate, heavy calcium carbonate, ordinary calcium carbonate), and potassium chloride (potassium sulfate) as raw materials, these materials are crushed to a certain fineness. Then, within the rotating bed of a drum granulator (or disc granulator), they are agglomerated and granulated through wetting and heating. During the granulation process, it is possible to add a small amount of phosphoric acid and ammonia to the drum granulator, if conditions permit, in order to improve the granulation conditions. The granulated material is dried, screened, and cooled to produce NPK compound fertilizer products; this is also one of the methods widely used internationally. In the early days, the United States, as well as countries in Southeast Asia such as India, Japan, and Thailand, all used this method for production. The raw materials used in this method are widely available and easy to obtain; the processing process is relatively simple, requiring little investment. It results in low production costs, rapid implementation, and high flexibility in production. It is also easy to adjust the quality of the products, and they have good versatility. All the raw materials used are solid, so there is little reliance on specific types of raw materials. Since it involves the secondary processing of basic fertilizers, environmental pollution is virtually non-existent. Given that most basic fertilizers in China are in powder or granular form, small and medium-sized compound fertilizer factories in China mostly use this method. At present, this production technology has become increasingly mature in China. The first entity in China to develop this production technology and hold the intellectual property rights for the complete set of equipment was the Shanghai Research Institute of Chemical Industry. 3) Partial slurry method: In recent years, building on the TVA urea process, the **semi-slurry method, and the granulation method, China has developed a new granulation technique that makes use of urine or **solution – namely the partial slurry method. This technology takes advantage of the fact that urea and **can form high-concentration solutions at high temperatures. Due to the high temperature of urine or **solution, its high solubility, and the large volume of the liquid phase, it is possible to directly spray this concentrated solution into the layer in the granulation machine. The liquid phase provided by urine or **solution is then used together with other solid base fertilizers and return materials for coating and granulation. This approach helps to reduce the amount of water or steam required, thereby lowering the water content in the granulated material. It also helps to reduce the amount of water needed for granulation, as well as the drying load and energy consumption. The granulated material is dried, screened, and cooled to obtain the (urea-based or nitrate-based) compound fertilizer product. At present, there are more than twenty entities in China that have developed and possess the production technologies related to this intellectual property, including the Shanghai Research Institute of Chemical Industry. 4) Blending method: According to the requirements for nutrient distribution, various solid basic fertilizers of nitrogen, phosphorus, and potassium that do not undergo significant chemical reactions and have roughly consistent particle size and roundness are used as raw materials. Through a specific blending process, a fertilizer with uniform nutrient distribution is produced. This method is simple to implement, with relatively low costs for equipment investment and processing; it is therefore a very practical and easy-to-promote approach. However, this method requires that the particle size, density, and roundness of the various basic raw materials be as consistent as possible during production, storage, transportation, and use, in order to prevent clumping of the mixture and issues related to low moisture absorption. At present, the shape and specifications of basic fertilizers in our country do not meet these requirements. Research has also shown that the rate at which P2O5 and K2O in uniform fertilizers are absorbed by plant roots differs from that in blended fertilizers (6 times and 4.6 times respectively), resulting in some differences in their efficacy. Additionally, the use of soil testing for fertilizer application is not yet widespread in our country, and such products are not yet recognized or accepted by farmers there. Therefore, the application of this law is currently subject to certain restrictions in our country. 5) Extrusion method: Extrusion granulation is a dry granulation process in which solid materials are agglomerated under external pressure. It has the following advantages: the production process generally does not require drying or cooling steps, it is particularly suitable for heat-sensitive materials, and it can also save on investment and energy consumption ； Simple to operate, with no waste emissions during production ； It is capable of producing high-concentration compound fertilizers with a lower concentration than ordinary ones, and organic fertilizers as well as other nutrients can be added during production as needed. However, the extrusion granulation method also has its drawbacks: ① As the key equipment in extrusion granulation, the extruder suffers from high material consumption and a high failure rate due to issues such as equipment manufacturing and the material of the components under pressure. ②The extruder has a low production capacity, making it difficult to achieve mass production. Therefore, this method is generally used for production scales of 30,000 tons per year or less. This method is currently mainly used for compound fertilizers such as rare earth ammonium carbonate. The units that possess this production technology include the Shanghai Institute of Chemical Technology, among others. 6) Melting method: The melt granulation process (natural cooling in tall towers and oil cooling) is a production technique for high-concentration urea-based compound fertilizers. It involves melting urea and mixing it thoroughly with ammonium phosphate and potassium salts, resulting in a high-quality, low-energy-consuming, and pollution-free production method for such fertilizers – the melt granulation process. The melt granulation process has been applied in fertilizer production, such as tower spray granulation for urea, tower spray granulation and twin-axis granulation for phosphate fertilizers, **tower spray granulation, and tower spray granulation for urea-phosphate-ammonium fertilizers. However, the use of this process for manufacturing high-concentration urea-based compound fertilizers is still an innovation in China. Since this process does not require the drying system, which represents the largest investment and energy consumption in traditional compound fertilizer production, and given the properties of urea and urea-based compound fertilizers, it is particularly suitable for the production of high-concentration triple (N, P, K) and dual (N, K or N, P) compound fertilizers with a high nitrogen content. Compared with the conventional compound fertilizer manufacturing process, the melt granulation process has the following advantages: (1) In the melt granulation process, the moisture content of the material is very low, so no drying step is required, **which saves energy consumption ； The percentage of qualified product particles in production is very high; therefore, the amount of material returned during the production process is low (almost none) ； (2) The product particles have a smooth and rounded surface, low moisture content (less than 1%), are resistant to caking, and possess high compressive strength (greater than 30 N), giving them strong market competitiveness ； (3) It features a favorable operating environment with no emissions of waste gases, waste liquids, or waste solids, representing a clean production process ； For this reason, the high-tower granulation technology is already a mature technology that has been widely adopted abroad.

Poster: May I ask my friend from Luxi, is the hydrogen-potassium mixed acid together with the tubular reactor used in high-tower granulation or in drum granulation? How many tens of thousands of tons has your company’s triple tower produced by June this year!

Tubular reactors should be used in the drum process. Regardless of the process used, the cost should be low, the appearance good, and the production process simple