A steel mill was experiencing increasing maintenance issues with an aging screen at their facility. The issues with the screen were causing considerable downtime and they were looking to replace the screen. The mill reached out to JVI for a solution. The new screen needed to classify metallurgical coke discharging from railcar unloading hoppers, sending the on-spec material to downstream equipment and off-spec material off for additional processing. The screen would need to retrofit into the existing work envelope, discharge coke from the railcar hoppers at 3 tons per minute (TPM), screen out –1.5” material, and withstand the highly abrasive nature of metallurgical coke to ensure a long service life and reduced maintenance. After reviewing the requirements with the customer, JVI was able to develop a vibratory classifying screen that would meet their needs. This proposed screen included:
Design Features
Retrofit Design
JVI’s engineers designed the classifying screen to fit and operate within the available work envelope of the existing process. The primary requirement was to accept the coke from the railcar unloading hopper and have the off-spec coke pass through the screen on to a conveyor belt while the on-spec material remains as “overs” and outlet to downstream equipment.
Single Deck Rubber Screen
A single level deck was chosen because the purpose of the screen is to classify the coke into two sizes, on-spec material constituting any material greater than 1.5” and off spec material being any material under 1.5”. The highly abrasive nature of coke necessitated a high wear life deck. To meet this requirement, an abrasion resistant molded rubber deck was chosen. The modular deck design simplifies maintenance by allowing individual sections to be replaced as they reach the end of their service life.
Liners
Metallurgical coke is a highly abrasive material. To ensure the longest possible operating life of the screen, JVI incorporated multiple different types and thicknesses of liners throughout the screen. These liners include 2” thick ceramic imbedded rubber liners, 1” & 2” thick ceramic liners, and ceramic-reinforced abrasion resistant composite.
Electromechanical “Unbalanced” Motors
Dual unbalanced motors were utilized as the drive mechanism. The motors were sized based on the weight of the screen to allow for process optimization through a variable frequency drive.
Single Mass Design
Single mass design utilizes fewer operating components, resulting in high reliability and low maintenance. There are no “tuning” requirements, and the screen can operate through variations in material.
Results
Upon customer review and approval, the custom classifying screen was manufactured and delivered. The customer elected to have a JVI technician on site during the commissioning of the screen to ensure proper installation, operation, and training personnel on proper maintenance practices. The commissioning of the screen went smoothly, and the classifying screen is now operational, sizing metallurgical coke at the required 3 TPM.