Roasting section

      The primary objective of the roasting process is desulfurization. Molybdenum concentrate, which primarily consists of molybdenum disulfide, is subjected to roasting in the absence of carbon. This process converts it into molybdenum oxide, with a sulfur content lower than 0.08%. Our roasting workshop with 25,000 tons’ annual production capacity has five rotary kilns, and it can be divided into feeding system, rotary kilns, discharging system, flue gas treatment system, and the (discharging) mixing system based on its function classification.

      Following extensive research and technical reformation, the flue gas treatment method was upgraded to high-temperature cloth bag dust removal for kilns No. 1, No. 2, and No. 5. This upgrade involved replacing the traditional low-temperature cloth bags with high-temperature metal cloth bags. The high-temperature metal cloth bags offer a longer service life and better filtration efficiency, resulting in significant reductions in cloth bag usage costs and replacement labor costs. Even after the dust removal process, the temperature of the flue gas remains as high as 200-300°C. Consequently, the waste heat boiler can harness this heat to produce steam, capable of generating 2-3 tons of 0.3 MPa steam on a daily basis during regular production operations.

      In April 2022, a innovative approach was implemented for the discharge system of Kiln No. 5. This involved the utilization of a slag cooler and a ball mill. The slag cooler, driven by a transmission device, rotates slowly. As a result, molybdenum oxide is discharged forward within the inner cylinder of the sleeve. Simultaneously, cooling water flows in reverse within the jacket located between the inner and outer cylinders, effectively absorbing heat and progressively cooling the molybdenum oxide. Once a sufficient quantity of cooled molybdenum oxide has accumulated, it is conveyed to a dry ball mill for the necessary crushing process, ultimately yielding qualified powdered molybdenum oxide. The use of the ball mill not only facilitates crushing but also fulfills the role of mixing, eliminating the need for a separate mixing process and related equipment to some extent.

Smelting section

      The smelting section plays a crucial role in producing Ferro molybdenum that meets the specific requirements and preferences of customers. This involves smelting the raw and auxiliary materials in various ratios to achieve the desired composition. The Ferro molybdenum is crushed to suitable particle sizes and then packaged as required. The smelting section can be subdivided into several systems, including the automatic feeding system, mixing system, smelting system, slag discharging system, iron excitation system, crushing system, and flue gas treatment system. Each system contributes to the overall process of producing high-quality Ferro molybdenum efficiently and effectively.

      After careful design and research, the automatic feeding system has been converted into a feeding platform. This modification eliminates the need for lifting the feeding hopper and feeding belt for raw and auxiliary materials, allowing the materials to be directly placed onto the feeding platform and fed into the silo. This transformation not only streamlines the feeding process and reduces equipment and power consumption, but also alleviates maintenance workload, lowers labor costs, and achieves multiple benefits.

      To further enhance the automation of the smelting process, JINDA MOLY has developed an in-house sand molding machine (currently in production). This mechanically-operated equipment enables the creation of sand molds, thereby reducing the labor intensity for workers and enhancing operational efficiency.

      The efficient utilization of heat energy from smelting tailings lumps is also a noteworthy aspect of our company. The temperature of the freshly discharged tailings lumps reaches as high as 1700 ℃. We utilize this high-temperature tailings lump to heat the boiler, generating steam for other production workshops. Based on our current output, our system can produce approximately 2 tons of steam at 0.3 MPa on a daily basis.

Sulfur dioxide workshop

      The sulfur dioxide workshop primarily manufactures liquid sulfur dioxide from sodium citrate. The workshop is comprised of various systems including purification, absorption, analysis/drying, liquefaction, storage and filling, as well as a cooling circulating water system. With our current production capacity, we can produce up to 15,000 tons of liquid sulfur dioxide annually.

1. Wet purification

      The roasting flue gas is expelled by a fan after being collected of dust particles through a bag filtration system. It first goes through the wet purification stage, where the flue gas enters a water washing tower. In the tower, it undergoes cross-flow contact with circulating water in a freely stacked plastic packing layer, effectively cooling the gas and removing impurities. After the washing process, the dust content in the gas is reduced to approximately 5mg/m and the temperature drops below 40 ℃. The gas then proceeds to the sodium citrate absorption stage to remove the sulfur dioxide from the gas.

2. Sodium citrate absorption process

      After the wet purification, the flue gas proceeds to the sodium citrate absorption stage. Firstly, the flue gas passes through an electric demister to eliminate moisture. Then, it will enter a three-stage absorption tower where it counter-currently interacts with sodium citrate solution (lean liquid) to absorb the sulfur dioxide presented in the flue gas. Once the majority of sulfur dioxide is removed, the flue gas will enter the sodium sulfite system for further absorption treatment. Finally, the flue gas is discharged once it meets the standards and requirements.

      The liquid sulfur dioxide produced by the sodium citrate in the sulfur dioxide workshop achieves a purity level of 99.99%.

Sodium sulfite workshop

      The Sodium Sulfite workshop, also known as the Sodium Sulfite workshop, plays a crucial role as the final stage in treating the roasting flue gas to meet the required standards. The Sodium Sulfite workshop consists of several systems according to the productive process, including the purification system, absorption system, circulation system, storage system, evaporation system, and heat energy recovery system. With an annual production capacity of 10,000 tons, the workshop ensures efficient tail gas treatment to meet the standards and regulations.

1. Purification, absorption

      The tail gas absorbed by the sulfur dioxide workshop may still contain trace amounts of sulfur dioxide gas. To comply with environmental protection regulations (where the state requires online monitoring equipment to detect values less than 850mg/m3), the sodium sulfite workshop utilizes a process called "desulfurization". This involves spraying a liquid alkali solution through five absorption towers to ensure that the emissions meet the required standards. Our company's online monitoring results are significantly lower than the national emission standards, demonstrating our commitment to environmental compliance.

2. Evaporation system

      After filtration and settling, the absorbed saturated solution is transferred into an evaporation kettle for the evaporation process. As a result, sodium sulfite is formed as white crystals. The average grade of these sodium sulfite crystals is above 96% and are ideally reaching a purity level of up to 98%.

Sulfuryl chloride production workshop

      The production of sulfuryl chloride follows the principle that sulfur dioxide react with the chlorine gas in the presence of catalyst (activated carbon) to yield sulfuryl chloride. The production process can be divided into several stages, including the chlorination process, rectification process, tail gas absorption, storage, and the filling. The production capacity of sulfuryl chloride is nearly 10,000 tons per year.

      After being heated and vaporized, the liquid chlorine and liquid sulfur dioxide are separately introduced into the drying tower for the purpose of drying. They then enter the reactor that is filled with activated carbon, where they undergo a reaction to produce sulfuryl chloride. Subsequently, the mixture enters the distillation tower for purification, and any unreacted gases are recycled back into the reactor. The input ratio of sulfur dioxide and chlorine gas is slightly excess in favor of sulfur dioxide to ensure a complete reaction with chlorine gas. Excess sulfur dioxide is recovered through a refrigeration condenser and subsequently absorbed by the tail gas absorption system.

      The sulfuryl chloride workshop achieves automated production through the Distributed Control System (DCS), ensuring efficient and precise operation. The product quality meets the advanced standards within the domestic market.