05
August
Fertilizer‑grade ammonium sulfate is a traditional ammonium‑nitrogen fertilizer and a typical by‑product from large‑scale chemical plants. Relying on the 600 kt/a caprolactam industrial chain relocation and upgrading project, Sinopec Hunan Petrochemical Co.,Ltd achieves large‑scale output of fertilizer‑grade ammonium sulfate and realizes resource recycling of chemical by‑products. Its products are supplied to domestic fertilizer markets and multiple overseas markets.The fertilizer‑grade ammonium sulfate of Hunan Petrochemical is generated as a by‑product of the caprolactam production unit. The complete ammonium sulfate unit is equipped with two production lines, with a maximum annual by‑product output of 900 kt of fertilizer‑grade ammonium sulfate and a daily output of around 2,600 tons under normal operation. Manufactured in compliance with national standards for fertilizer‑grade ammonium sulfate, the product features approximately 21 % total nitrogen content, white crystalline appearance, low organic impurities and low powder ratio with stable quality. It can be directly used as nitrogen fertilizer and serves as an important basic raw material for compound fertilizer production.As a chemical by‑product, its core advantage lies in resource recycling. While producing caprolactam monomers, the main caprolactam unit generates ammonium sulfate crystalline materials as by‑products. Through process control to stabilize crystal quality, the enterprise converts chemical by‑products into agricultural fertilizer raw materials, realizes closed‑loop material circulation in the industrial chain, reduces waste discharge and conforms to the circular‑economy development trend of the chemical industry.In terms of production and operation, Hunan Petrochemical has carried out multiple process optimizations for its ammonium sulfate business. It has launched wet‑material loading and large‑granule ammonium sulfate toll‑processing projects. Part of wet ammonium sulfate material skips the full drying process and is sent to partners for extrusion processing into large‑granule ammonium sulfate. This mode eliminates the high‑energy‑consumption drying section, cutting steam consumption by about 40,300 tons and power consumption by approximately 17 million kWh annually. It also lowers water consumption and dust emissions, improves on‑site working conditions and balances cost reduction and green production. Extruded large‑granule ammonium sulfate features regular particle shape, adapts to mechanical spreading and has a longer nitrogen release cycle, well‑suited for large‑scale agricultural planting overseas.For the market, Hunan Petrochemical cooperates with Sinopec Chemical Sales Central‑China Branch and Sinopec Chemical International Trade for domestic supply guarantee and overseas export businesses. Domestically, crystalline ammonium sulfate is supplied to compound fertilizer manufacturers and agricultural‑material distributors. It can be applied as base fertilizer or top‑dressing for most crops and performs well on acid soil. In overseas markets, its products have entered Southeast Asia, Brazil and other regions. Large‑granule ammonium sulfate has been exported to Romania and other European countries to open up European market access. Exports once accounted for 50 % of total sales, making it one of the enterprise’s key export products.In application, fertilizer‑grade ammonium sulfate is an acidic nitrogen fertilizer that supplies crops with nitrogen and sulfur nutrients. It is suitable for field crops such as rice and corn as well as acid‑loving cash crops. It can be applied directly or used as raw material for compound fertilizer manufacturing. During storage and transportation, it shall be kept in dry and ventilated warehouses and shall not be mixed with alkaline materials to avoid nitrogen loss caused by chemical reactions.For chemical enterprises, the by‑product ammonium sulfate business poses strict requirements for unit stability, product quality control and production‑sales coordination. Hunan Petrochemical has set up special research teams to remove unit bottlenecks and strictly control intermediate process indicators to guarantee stable purity and particle size of finished ammonium sulfate, ensuring stable co‑production of main‑product caprolactam and by‑product ammonium sulfate. This model provides a referable case for by‑product resource utilization among domestic large‑scale petrochemical enterprises. It converts chemical by‑products into fertilizer raw materials for agriculture and builds the connection between chemical industry and agriculture.Against the backdrop of differentiated global fertilizer raw‑material demand, market requirements for crystalline and large‑granule ammonium sulfate keep growing. Supported by stable by‑product supply from its caprolactam chain, Sinopec Hunan Petrochemical will continue to secure domestic supply and expand overseas markets, and further explore the market value of circular‑chemical products.
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