Scrap Criteria and Recycling Workflow for Molybdenum Electrodes

Once an electrode is removed, filing it straight into scrap is not the right move. Some units have only damaged threads at the end while the body can still run at reduced duty; others look intact on the surface but already contain internal cracks. Written criteria prevent both unnecessary scrapping and disputes at the recycling step.

Where to Start with the Criteria

Common criteria fall into four groups: cracks, oxidation depth, dimensional loss and joint failure. Cracks can be found visually with penetrant inspection, concentrating on the ends and on abrupt section changes; oxidation depth can be judged from a section cut or by wall-thickness measurement; dimensional loss is measured by diameter consumption and straightness; joint failure shows up as thread damage, rising contact resistance or loosened clamping.

The call should be confirmed jointly by equipment and process personnel, and recorded with the electrode number, service hours, failure symptom and photographs. Judging from appearance alone easily misses internal defects.

Before judging, confirm the actual operating conditions. If the failure occurred where current density was high or cooling was inadequate, the rest of the lot may not share the problem, so the whole lot should not be scrapped.

Classification and Temporary Storage

• Reusable at reduced duty: dimensions still acceptable, only minor surface or joint issues.
• Repairable: threads can be restored, ends can be re-machined.
• Direct recycling: through-cracks, heavy oxidation or clear dimensional loss.
• Pending judgement: symptoms unclear, further testing required.

Store each class in a separate area with a tag to prevent mixing. Molybdenum is heavy, so stacks should not be too high, to avoid falls causing secondary damage. Keep the area dry to slow further oxidation. The holding area is best placed close to the furnace teardown position to cut long hauls; harden the floor and set electrodes on wood or rubber pads so they do not touch steel structures directly.

Weighing, Handover and Documentation

Weigh and record each piece before recycling, and compare with the theoretical weight and the previous weighing to estimate consumption. The handover sheet should state grade, quantity, weight, number and judgement class, and be signed by both parties. For transport between plants, attach a packing list and safety notes.

Remove surface deposits before weighing, otherwise the higher weight distorts the consumption estimate. Use one unit throughout; mixing kilograms and tonnes causes settlement errors.

For electrodes with coatings or combined with other materials, state the combined condition at handover so the recycler can plan dismantling. For the related quality judgement and record requirements, see the practices described on our quality management page.

Settlement Methods and Residual Value

Recycling is usually settled either by converting on molybdenum content, or by multiplying the whole-piece weight by the prevailing price factor. The two methods can give different results, so fix the method in the contract. Keep the testing or sampling records with the settlement documents to avoid disputes over weight and content.

If the recycler requires on-site sampling, retain and seal a duplicate sample for re-testing should the result be challenged. Residual value income can offset the total life-cycle cost of the electrode, a point often overlooked in annual purchasing analysis; booking the recovered amount for each lot informs the next round of selection.

Scrapping a part does not invalidate the failure information. Link judgement, classification, weighing and settlement into one workflow, and you recover material value while also learning what went wrong in service.