What Is a Steam Dryer?

The steam dryer is mainly used for the secondary drying of the copper concentrate that has been pre-dried. The copper concentrate with a moisture content of 8% to 10% after pre-drying is prepared into a copper concentrate with a moisture content of 0.3% Finally, the dried copper concentrate is transported into the flash furnace reaction tower and mixed with the process air to form matte and slag, thereby completing the copper concentrate smelting process.

Guiye-System Steam Dryer System is an important process in the whole process of Guiye 1 # flash furnace copper smelting.

Guiye-system steam dryer is composed of drive motor, reducer, drive pinion, driven ring gear, dryer cylinder, steam coil, supporting wheel set, steam distribution valve and other parts ^[2]

Steam dryer is one of the core equipment for preparing materials for flash furnace smelting. Copper concentrate with higher moisture content is dried by steam dryer to obtain copper concentrate with lower moisture content. The dried copper concentrate is finally dried. Conveyed to the flash furnace reaction tower.

The copper concentrate mixture coming out of the batching silo is transported to a movable belt by the mixing 1 # to 6 # belt conveyor. The movable belt then transports the copper concentrate to the interior of the steam dryer and enters the copper inside the steam dryer. The concentrate rotates with the steam dryer. Under the action of gravity, the copper concentrate mixture comes into contact with the steam coil, and physical changes occur. In this process, the water in the copper concentrate continuously evaporates to meet the predetermined drying requirements, thereby completing During the entire copper concentrate drying process, the finally dried copper concentrate mixture is transported to a flash furnace for smelting.

The advantages of steam dryer over traditional drying equipment are as follows:

(1) The equipment occupies a small area and the structure is neat;

(2) The system is fully sealed without leakage;

(3) Large amount of drying, continuous operation;

(4) Drying volume is easy to adjust and can meet the production needs of different drying volumes ^[2]

Since the Guiye-system steam dryer was put into operation in May 2013, its preliminary operation has been basically stable, but it started to run in April 2015. As the steam coil inside the steam dryer has reached the service life, some steam coils have leaked. Therefore, the maximum drying capacity of the steam dryer is also affected.

Since April 2015, the maximum copper concentrate drying capacity of Guiye-System steam dryer has gradually decreased. This phenomenon also requires the relevant engineering and technical personnel of Guiye to find and analyze the causes of related problems, and finally find a solution to the problem ^[3]

Aiming at the phenomenon that the maximum drying amount of Guiye-system steam dryer gradually decreases in the daily production process, through careful inspection by relevant engineering and technical personnel of Guiye, finally found the factors that cause this phenomenon.

This phenomenon directly leads to the continuous reduction of the copper concentrate drying capacity of the Guiye-system steam dryer, which will eventually affect the full-loading amount of the flash furnace. In order to confirm the normal drying amount of Guiye-system steam dryer and stabilize the production of Guiye-system flash furnace, after the continuous efforts of Guiye metallurgical engineering technicians in recent years, combined with daily work experience, we The leakage of the coil inside the dryer is analyzed and classified, and corresponding solutions are proposed.

1 Fault management measures for the corrosion and wear of the steam coil inside the steam dryer by copper concentrate

In October 2015, a system was overhauled once every two years, and all the steam coils inside the steam dryer of the Guiye-System steam system were replaced. At the same time, the steam leak inside the steam dryer occurred in daily production. We found that the steam coil installed inside the dryer is most prone to corrosion and wear of the steam coil in the area of 5m from the feed end of the steam dryer.

In view of this situation, in daily production, our troubleshooting measures are: Remove the steam inlet and outlet pipes on the end plate of the outlet of the steam dryer, and plug the remaining joints with plugs.

At the same time, through careful inspection and analysis, relevant engineering and technical personnel of Guiye found that the factors that caused this phenomenon were as follows.

(1) When the copper concentrate has just entered the steam dryer, the moisture content is relatively high. At this time, the copper concentrate is liable to adhere to the steam coil.

(2) Copper concentrates are selected through beneficiation. During the process of beneficiation and selection of concentrates, the reactants added contain chloride ions. Especially in the slag beneficiation of smelting smelting, the fluoride ions generated during smelting; after the copper slag is selected into the concentrate, when these harmful substances enter the steam dryer, the corrosion of the steam coil is very severe.

(3) When the material of the movable belt enters the interior of the steam dryer, there is a parabolic drop. This phenomenon is one of the important reasons for the wear of the steam coil at the feed end of the steam dryer.

In view of this series of factors, the relevant engineering and technical personnel of Guiye proposed to improve the material of the existing steam coils and choose a more corrosion-resistant duplex stainless steel steam coil to replace the currently used 316L stainless steel steam coil. At the same time, it is recommended that the factory add process equipment to remove fluoride and chloride ions in the future production process.

2 Fault management measures for abrasion of steam coils due to installed sockets

When the steam coil inside the steam dryer is working, the internal working medium is saturated steam. Therefore, during normal operation, the axial and radial dimensions of the steam coil have a certain amount of expansion relative to its own cold state. In this case, a certain gap should be reserved between the steam coil and the coil mounting seat. However, during the overhaul of the steam dryer in October 2015, we found that the wear between the steam coil and the coil mount was severe.

In response to this phenomenon, we performed relevant parameters and technical analysis on the above situation, and finally found the root cause of the problem: Mainly due to the excessively large clearance between the steam coil and its mounting seat during the installation of the steam coil, which eventually caused steam There is relative movement between the coil and the mount, which causes the steam coil to wear. Guiye engineering technicians consulted the relevant technical data, and proposed to improve the existing steam coil mounting seat, reduce the gap between the steam coil and the mounting seat, and properly add copper gaskets between the steam coil and the mounting seat. When the steam coil is working normally, the steam coil and its mount are firmly held together, thereby reducing the relative movement between the steam coil and the mount, and ultimately extending the service life of the steam coil ^[2]

Aiming at the operating characteristics of Guiye-system steam dryer, we carry out the following aspects of management and management of its key parts.

1 Steam coil inspection

The process operator took advantage of the opportunity of weekly flash furnace shutdown and inspection to move the mobile cart away. The producer entered the steam dryer and checked the internal coil for leaks.

2 Equipment lubrication

During the daily inspection process, a key inspection of the oil reducer of the main reducer, the supporting parts of the supporting rollers and the supporting parts of the supporting wheels of the supporting wheels is carried out, and the oil circuit is checked regularly. Generally, the additional lubricating oil for the bearing blocks is: 2 # lithium fatty oil, and the main reducer is mainly to observe the oil level and the emulsification or carbonization of the oil. Usually, the main reducer is replaced once a year (Mobil 220 #).

3 Measure the operating temperature

During the daily inspection process, a key inspection is performed on the key equipment of the main reducer, the idler bearing housing and the idler positioning bearing housing, and the operating temperature is measured. Outer surface temperature of the main reducer: Generally 33 ~ 55 . Roller bearing housing temperature: Generally 27 ~ 45 . Roller positioning wheel bearing seat temperature: Generally 27 40 .

4 Check the braking system

During the daily inspection process, carry out daily inspections on the hoop wheel and hoop grinding discs; when the car is stopped and inspected every week, measure the thickness of the hoop wheel and wear plate. Thickness of hoop wheel: 10; Thickness of wear-resistant plate: 4.

5 Measure the clearance of the coupling

During the weekly inspection and shutdown of the furnace, the coupling clearances at the above two locations are inspected and measured. The gap between the main motor and the main reducer coupling: 0.5 ~ 5mm. Back clearance between main reducer and drive shaft coupling: 10mm.

6 Check the gear system

Take the opportunity of regular or annual repair, open the cover of the gear system, and check the wear of the driving gear and driven gear: Tooth clearance: 16; Back clearance: 1; Tooth surface meshing area: 70 % Tooth area ^[3]

Through continuous improvement and innovation, the operation of Guiye-system steam dryer is becoming more and more stable, and the frequency of failure of Guiye-system steam dryer is becoming less and less. This phenomenon not only reduces the Guiye-system steam dryer The maintenance cost of the machine also guarantees the full load operation rate of Guiye 1 # flash furnace ^[1] .