No Maintain, No Gain

Sept. 1, 2011

Any piece of machinery with moving parts (and even some without, as computer users know) will need periodic maintenance. Metal stresses and wears out; belts fray and snap; parts that rub against others need lubrication. As machinery is increasingly used in materials recovery facilities (MRFs), these firms must have maintenance schedules in place, especially since their machinery is subjected to objects of varying size, density, weight, and shape. In addition, although machines eliminate a certain amount of manual labor, there are still workers onsite, and machines must be calibrated so accidents don’t occur. For example, a too-fast conveyor belt might cause sharp objects such as glass or metal to fly off the belt, towards workers. By the same token, workers must be vigilant to stop in-use problems, such as removing items that might jam machines.

Sorting by Light
“Maintenance is extremely important; anything that halts the system will be costly to the operator,” says Parts and Service Manager Ed Hurlburt, of Eugene, OR’s Bulk Handling Systems (BHS), www.bulkhandlingsystems.com. “There aren’t too many places one can have a failure that won’t stop the MRF machines. If something breaks, the system doesn’t run. If the system is down for a couple hours, that’s bad. If it’s down for a couple days-that’s horrible! Operators need to have a proper understanding of how to take care of the equipment, as well as having sufficient spare parts available to mitigate risk of downtime.”

BHS provides preventive maintenance, repair, and training. “Our people will inspect the system. This “˜walk-through’ is done quarterly, but the machine owners must inspect the system daily. During our inspection, our lead engineer has 30 years experience, and gives very precise reports. For example, his report might say something like: “˜It looks like this screen needs replacing. The return rollers are worn.”

If a site contains a BHS/NRT MultiSort IR/ES Combo System or the BHS/NRT SpydIR, more than belts and screens need to be inspected; as an optical system sorts the materials, the scanners need to be kept in proper calibration. “Materials are sorted by infrared  scanners. Items can be sorted by color, which is helpful in sorting glass, PET, HD, and other plastics-also if light goes through it, such as in the case of opaque plastic. Aluminum cans are also sorted here. Once items are identified, a directed burst of air pushes lighter desired plastics into the appropriate chute. One machine, the rugged and robust MultiSort IR/ES Combo System, detects PET and HDPE natural.

“These optical systems need to be calibrated properly,” Hurlburt goes on. “However, mechanical parts must also be calibrated. Is the belt going at the right speed for the scanner? They have to be in sync for everything to work properly. At least once a shift, workers have to clean the optical lenses, to make sure no material is stuck in there.”

Is enough time available for this maintenance? “Some plants might work 24 hours; however, most I see are one or two shift operations. Time is required to perform that maintenance and lubrication.”

Various modules of the BHS system perform different tasks. The BHS OCC Separator automatically separates old corrugated containers from other fiber, various plastic and metal containers and debris. “Incoming trash moves uphill, across a variety of screens. Our Debris Roll Screen has been designed to process single stream, Municipal Solid Waste (MSW), Construction and Demolition (C&D) waste, wood waste, compost, green waste, plastics, glass, tires and other miscellaneous materials. Two other screens are regularly used in a MRF-NewSorter, for newspaper, and Polishing Screens.”

The BHS MRF systems sort through all the material that comes in, discarding what can’t be recycled. “You go through this stuff and what’s left over is residue. Some can be composted, some has to be landfilled. Some left-over material can be burned for fuel. In fact, we’re looking into trash-to- energy; we have a partner company building the equipment that will make that fuel.”

Ricky Lopez, MRF manager of San Jose, CA’s GreenWaste Recovery Inc., has been using BHS equipment approximately four years. “We have a BHS dual-line system, for single-stream and MSW. We collect nearly everything-C&D, foodwaste, wood, OCC, MRP, yardwaste, MSW, single-stream recyclables for commercial and residential-and it all has to be sorted out.

“We maintain the equipment daily, monthly, quarterly, and yearly,” Lopez goes on. “The tasks include lubrication, replacing worn polishing discs, replacing or relacing conveyors, cleaning electrical components to prevent shorts, and many other tasks. Maintenance is the backbone of any operation, since downtime costs money. BHS has a new program many facilities should take advantage of: its Preventive Maintenance classes. Preventive Maintenance is the key to equipment longevity.”

GreenWaste Recovery operated some of BHS prototype machines. “We are pleased with their equipment, but like all prototypes, there were some preliminary problems with the MSW line. However, BHS has a great staff, which addressed and sent replacements and parts to remedy the problems. Overall it’s a great company, and their products are second to none.

“We currently sort manually at our transfer station, and the automated system improves operations. It diminishes labor while increasing recovery and diversion rates. Like all automated equipment, regardless of manufacturer, it dramatically improves processing,” Lopez concludes.

Machines Moving C&D
As might be expected for its weight, C&D waste gives MRF equipment more of a beating. However, careful maintenance will keep the lines running.

Palatine, IL’s MBL Recycling has been using equipment from Crystal Lake, IL’s General Kinematics Corp., www.generalkinematics.com for the past five years. “We own two of their finger-screen decks and one airknife de-stoner,” says MBL’s co-owner Robert Lenzini. “The de-stoner takes lights from heavies, cleans up the rocks and bricks, and takes other stuff-such as paper, plastic, wood-out of the stream. This certainly helps, as we take mixed loads of C&D debris. The de-stoner will take out everything from a 1-inch rock, which is then crushed to road aggregate.” GK Single Knife De-Stoners use air instead of water to separate heavy product from light product, eliminating the mess and environmental hazards water separation creates.

Lenzini performs all needed daily maintenance, which may account for his machines’ robust “health.” “The screens are very simple; an electric motor runs them, and some of its parts are still original! The airknife is also electricity-driven. Once in a while we have to replace a bushing on an arm, but that’s not so bad-that’s a low-cost maintenance item. Once a week we clean the lower deck on the big screen, as it collects dirt buildup. The smaller deck doesn’t have any maintenance needs. A little bit of grease on fittings once a week, maybe six to eight areas on each unit, and grease applied to other parts of the plant-belt fittings, et cetera-and that’s about it.”

MBL Recycling uses finger screen decks. “Ours is a two-line system: A and B lines. Recyclables are cut into two different sizes. We screen to 12-inches or smaller on the A line. Material then goes to a 3-inch screen, removing dirt, et cetera-then items go to the B line. At that point, the airknife system blows everything from the rock. Wood goes into a grinder, creating a 3-inch-minus product.”

The operation, which is all under-roof, runs eight-hour shifts, five days per week, “…although we’re open a half-day on Saturdays for intake.” Is Lenzini’s business an outgrowth from landfill prohibitions? “Not in Illinois, yet. Chicago did say 50% of C&D waste has to be recycled; there are two or three plants in the city proper, so we don’t see too much of theirs. Almost anything can go into landfills; we haven’t seen a push for restrictions in the suburbs just yet. The push here was LEED certification; companies went green, and they get LEED points from recycling. Another advantage we offer: our intake rates are a little cheaper than tipping fees at a landfill.”

Whatever cardboard and paper that comes in gets recycled. “Everything else gets shipped out to someone else for further use, and the wood is burned for fuel. We’re recycling asphalt shingles and send that to someone who turns it into hot mix. There are not yet wallboard recycling programs in Illinois. In fact, US Gypsum in Waukegan asked us about recycling theirs-I wondered, Why don’t they reuse it?”

Small but Mighty
Despite its small footprint (nominal 7000 square foot space), the MiniMRF system (www.minimrf.com) can move a significant amount of waste. “MiniMRF has a throughput of up to 50 tons per hour, which corresponds to a population of about 250,000,” says Envision Holdings’ Steve Viny.   MiniMRF LLC is a joint venture between Prfection Engineering (a subsidiary of Envision) and Novelis. “Certainly, to keep the system operating at peak performance, the most important thing is preventive maintenance and maintaining an appropriate inventory of critical parts. As the “˜critical parts’ varies with machines, one has to know which parts are “˜yours.’ We do have periodic maintenance tasks, times in which we have to visit a customer’s site, and we do all our own work.”

The first step in preventive maintenance is to inspect the equipment. “MiniMRF needs daily cleaning, which includes debris removal; most of this can be blown off with air,” Viny explains. “Every MRF has spinning shafts; and, anything in the wastestream that can wrap around a shaft, usually will. That debris must be removed. Operators should check for belt alignment and tension; inspect pulleys for debris; and lubricate bearings as required. In general, operators will want to keep the equipment clean, dry, and free of foreign debris.”

The MiniMRF system handles residential solid waste, and separates the recyclables in a chain of machines. “The base MiniMRF consists of three modules. Prior to waste placement in the first module, large ferrous metals, such as white goods (refrigerators, stoves, et cetera) and bulky waste such as rugs or furniture would be pulled out of the stream. Ferrous metals, such as toaster ovens, microwaves, or institutional soup cans, “˜heavies’ such as brick and concrete, and light combustible-items for conversion technology-would also be removed at this point. The bulky waste (and heavies) would go to the landfill.”

Module two pulls out small ferrous materials, organic waste, and glass. Metals are recycled and the organic/glass mix is composted for use as alternative landfill daily cover (ADC).

The third module removes mid-size metallics, such as steel and aluminum cans. The remaining material-consisting principally of light paper and film plastic-is combined with the light fraction in module one, to be used as Engineered Fuel. “These three MiniMRF modules work in harmony together, to allow for high through-put capacity in a small space-and with low labor costs. The entire MiniMRF system requires only three people to operate it. One feeds the system by using an excavator or grapple; one takes the sorted material away with an end loader; the third watches the line, and provides assistance where needed.  It’s almost totally automated, and all under-roof.”

How would cities considering a MiniMRF system know how much to buy? “We would look at the city’s waste composition, waste volume, and geographic area, then size the MiniMRF solution accordingly. For a population of a million, would it be best to have one system in a single area, or multiple units around the area, which would save travel costs? As a rule of thumb, we suggest one MiniMRF line for populations of a quarter-million. For areas that want to quickly reduce waste going into their landfills in a meaningful way, MiniMRF would be a perfect solution,” Viny concludes.

About the Author

Janis Keating

Janis Keating is a frequent contributor to Forester Media, Inc. publications.