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and process the stored shakeout sand from trials through the magnetic separator.


• Debug the heater/coolers and pneumatic transport system.


Fig. 3. The continuous mixer fills a drag mold in the flaskless molding line.


resolved and reduced concerns about cracking associated with the furan binder system. voestalpine Nortrak also made several trackwork casting molds with segments faced with 200- lb. batches of furan bonded chromite that produced good surface quality. Te goal was to be making furan


bonded chromite/silica molds with rec- lamation by April 2014, while continu- ing full production. Te new molding lines required relocating the plastic injection equipment, pattern shop and manganese casting processing from cleaning through shipping. voestalpine Nortrak arranged for the new core mixer (120 lbs./min.) to be delivered by August 2013 to increase the scale of the molding trials and be able to run small trackwork molds with furan bonded new chromite facing and furan bonded new silica backing. Te project timeline for the sand sys-


tem changeover was initially estimated to take roughly seven months from project approval, though it ended up requiring a full calendar year. Te project delays were mostly due to infrastructure issues not related to the sand system change. Because the new olivine


and reclaimed olivine/ silica silos were planned to be used for reclaimed chromite and silica stor- age, the old sand system had to be shut down before the new one could operate. A two-week shutdown was scheduled


for March 2014. Te 1,200 lb./min. mixer (Fig. 3)


was installed just before the Christmas shutdown. Day bins were being filled by crane from supersacks to enable equipment debugging. Chromite/silica shakeout sand from these test molds was being segregated from the ECP- bonded olivine/silica production molds until the shutdown, when it could be processed through the new cooler/clas- sifier for transport to the 35-ton silo located above the new magnetic separa- tor. Te magnetic separator is the crucial piece of equipment for the chromite/ silica reclamation system. During the planned two-week shut-


down, the following needed to happen: • Empty and relocate two large sand silos from the west side of the plant to the south side. The foundation and elevated platform were ready. • Commission the magnetic separator


• After the sand silos were empty, the ineffective inverted, partial cone anti-segregation device was replaced with the inverted, full cone version. The silo relocation and magnetic separator commissioning proceeded smoothly, meeting the April 2014 goal, a year after the initial planning meeting.


Assessing the Installation After the project was complete,


voestalpine Nortak asked itself some straightforward questions: How is the new system working? How is it being controlled? Since start up, production goals


have been achieved and the project has exceeded budgeted cost sav- ings. The goal is to keep sand usage at or below the business plan with a new chromite sand addition rate of 12%, including new chromite cores. Currently, patterns are being faced with a blend of 9.6% new and 90.4% reclaimed chromite and backed with a blend of 11% new and 89% reclaimed silica. Current stable binder addition rate is 1% for both facing and backing sand. Acid levels vary between 25-45%, depending on resin and blending technique. Revised Wash and Application


Fig. 4. The distributor plate features mouse holes to prevent clogging. 34 | MODERN CASTING February 2016


Practices: Sporadic surface quality issues were discovered with the olivine/magne- site wash on the 90/10 reclaimed chromite/new chromite facing sand. Te olivine/magnesite coating had been used success- fully on the new olivine sand facing in the old sand system. voestalpine Nortrak tried a magnesia (MgO) coating, which improved surface quality as measured by substan- tially reduced cleaning times. In addition the following controls were implemented: • Baume control was


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