Screw Classifier for Recycled Metal Turnings

General Description

Sims Metal Management is the world’s largest metal and electronics recycler, with more than 270 facilities on five continents, including 120 in North America. At the Hartford, CT facility Sims needed a method for cleaning and conveying titanium and nickel scrap machining turnings as part of a recycling process. The quality of the recycled material and the rate of processing were of utmost importance. Cleaning solution leakage from the process was not allowed. Traditional shaft seals on existing equipment were leaking and Sims did not want to duplicate this problem. The equipment would need to be extremely heavy-duty for long life and of stainless steel construction. KWS was able to provide the ideal solution in the form of specially designed material classifiers.

Design Parameters

KWS Advantages

KWS properly sized the classifiers based on both the solids and liquids flow rates. The liquid is used to wash the turnings as they are being conveyed out of the classifiers. The liquid is circulated in the classifier, then cleaned and reused. The turning are conveyed out of the classifier tank up an incline and sent for further processing. KWS was able to perform the calculations required in order to properly size and design several classifiers that would meet the cleaning and conveying capacity goals. KWS worked closely with the engineers and plant management at Sims to ensure design of the classifiers. Materials of construction, cleaning solution tank size and design, overall equipment layout constraints, degree of conveyor incline and distances between the inlets and discharges were all jointly determined by KWS and Sims engineering personnel.

Special Features

To meet the requirements for corrosion resistance, KWS constructed the classifiers from 304 stainless steel material. Special internal stub shafts and bushings for the lower end of the classifiers were designed to eliminate any leakage of liquid. The externally bolted stub shaft was designed to be removable and provide easy maintenance for the lower bushing. KWS incorporated heavy-duty 304 stainless steel construction for the screw flights and special replaceable abrasion resistant steel trough liners for long life. Because the tanks will need periodic cleaning, KWS added bolted and gasketed removable cleanout covers on the tank body. The drive units provided high torque for startup under loaded or upset conditions. Each classifier was provided with structural supports and a skid, making the units mobile.