Simple Solutions That Work! Issue 12

21 BACK TO BASICS Contact: DAVE WHITE [email protected] METAL MELT LOSSES This also is a good time to discuss the value of metal lost. Here is a recap of their typical metal losses. Dry Hearths Direct Fired: 3-3 ½% based on firing at large solids Dry Hearths Direct Fired: 7-12% based on firing at scrap ranging from beefy sections to light gauge High Headroom Side Wall Fired: 3½ to 4% based on melting heavy solids High Headroom with External Charge Well: 3- 4 % majority of melting done in well of clean materials Stack Melters Direct Fired: 1% when melting all ingot and 5-7% when melting a lot of lightweight scrap. Low Headroom Radiant Roof Melter: 3% average based on mixed load melting Electric Glow Bar Melter: 1% or less average based on ingot and/or scrap melting in the charge well. Crucible Melters: 4-5% EXAMPLE If we were to add an additional ½% of metal loss to your operation of 7,000# per hour melt rate based on a three-shift operation, here are the numbers you would be losing. Today on the spot market Aluminum had a value of $1.00s a pound: • 1% of 7,000 pounds is 70 Pounds per hour X 20 hours of melting a day equals 1400 pounds at a value of $1.00/# equals $1,400.00 dollars a day or if production runs 325 days per year that is $455,000 dollars over a year. That’s on just on one furnace! As you can see choosing a furnace that consumes less energy and has a lower overall melt loss can save your company big money. Little things to help furnace efficiencies: 1. Install well covers whenever the furnace is idle for longer than a half hour. 2. Install a half flue cover over the flue during long idle conditions. Warning: You must remove flue cover before turning the furnace to high fire. At low fire the flue opening is still sized for 100% output of the burners. If you do not have automatic flue pressurization your holding efficiencies will drop considerably. The furnace may not have to be on high fire as much. 3. Make sure the furnace is used at full capacity and charged at a quarter of its hourly rated capacity every 15 minutes. Overcharging the furnaces causes dramatic swings in temperature and increased sludge build up on the floor of the furnace. The more sludge you have on the floor the less likely your furnace will melt at rated capacity. The furnace may not melt anywhere close to the Btus/lb of metal melted, which it was designed to do. 4. Reduce your molten metal temperature over weekends by 20° or more if feasible. 5. Clean furnaces during idle shifts or idle times. But clean them daily! This will cut down on the amount of oxides growing in the furnace. Oxide is dense and absorbs additional Btus from the metal. Don't over flux your melters. Over fluxing of the wails can break down the binder in the refractory and cause premature erosion of the belly band area. 6. Don’t over buy a furnace. Buy only what you need. We (as most furnace manufactures should) connect more power than you will ever need at rated capacity. This gives you a passing gear should you ever need it. Under utilization of the furnace will result is loss of efficiency unless you have the ability to shut burners off or reduce electrical output during the lesser capacity production runs. All of the Schaefer furnaces have full proportioning controls so you only use what you need to melt. The extra capacity is there as a back up when you get power outages or get behind and need to melt more metal than rated capcity. I know there is a lot to consider when buying an aluminum melting furnace. Spend the time to properly determine the right solution for your company’s goals with a furnace that fits your production floor space and provdes you witih the highest quality metal at the right temperature with the minimum about of energy spent.